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http://mathhelpforum.com/calculus/98439-solved-can-someone-give-me-start-integrating-please.html
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# Math Help - [SOLVED] Can someone give me a start integrating this please?
1. ## [SOLVED] Can someone give me a start integrating this please?
$
\int
\frac{1}{10 - kv^2}
\, dv
$
2. Hi Bucephalus
If k is a constant, you can try :
1. Let : $v=\frac{\sqrt{10}}{\sqrt{k}} \sin \theta$
or
2. Partial fraction by first factoring the denominator
Originally Posted by songoku
Hi Bucephalus
If k is a constant, you can try :
1. Let : $v=\frac{\sqrt{10}}{\sqrt{k}} \sin \theta$
or
2. Partial fraction by first factoring the denominator
Hi Songoku
Two things:
1) I want to understand how you got that expression in your first helper.
2) I have done partial fraction decomposition before, but I don't understand what you're saying "factoring the denominator"
$
\frac{1}{10} - \frac{1}{(kv)v}
$
I'm sorry, I'm really having trouble understanding.
bucephalus
4. Originally Posted by Bucephalus
[snip]
2) I have done partial fraction decomposition before, but I don't understand what you're saying "factoring the denominator"
$
\frac{1}{10} - \frac{1}{(kv)v}
$
I'm sorry, I'm really having trouble understanding.
bucephalus
Factorise $10 - kv^2$.
And if you're studying at the level of integral calculus I would sincerely hope that you know that $\frac{1}{10 - kv^2}$ is certainly NOT equal to $\frac{1}{10} - \frac{1}{(kv)v}$ !!!
5. Hi Bucephalus
I want to understand how you got that expression in your first helper
It's because I want to use trigonometry identity : $1- \sin^2 \theta = \cos^2 \theta$
Using $v=\frac{\sqrt{10}}{\sqrt{k}} \sin \theta$ will change the denominator to :
$10-kv^2=10-10 \sin^2 \theta=10(1-\sin^2 \theta)=10 \cos^2 \theta$
In fact, you also can use : $\frac{\sqrt{10}}{\sqrt{k}} \cos \theta$ because it will be relevant to identity : $1- \cos^2 \theta = \sin^2 \theta$
If the question turns out to be $10+kv^2$ , you can use substitution : $v=\frac{\sqrt{10}}{\sqrt{k}} \tan \theta$ because it is relevant to identity : $1+\; tan^2 \theta = \sec^2 \theta$
For the second one, follow Mr. F suggestion :
Factorise $10 - kv^2$
6. ## Factorising
so factorise this.
$10 - kv^2$
The only way I can think of to factorise this is:
$10(1-\frac{k}{10}v^2)$
Is this what you mean?
7. $10-kv^2 = \sqrt{10}^2-\sqrt{k}^2v^2$
now using the difference of two squares $a^2-b^2 = (a-b)(a+b)$
You get
$10-kv^2 = \sqrt{10}^2-\sqrt{k}^2v^2 = \sqrt{10}^2-(\sqrt{k}v)^2 = (\sqrt{10}-\sqrt{k}v)(\sqrt{10}+\sqrt{k}v)$
So now $\frac{1}{10-kv^2} = \frac{A}{\sqrt{10}-\sqrt{k}v}+\frac{B}{\sqrt{10}+\sqrt{k}v}$
Find A and B and the integral will be alot easier in this form.
8. ## Thanks Pickslides
That's an awesome response.
|
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|
https://www.dostips.com/forum/viewtopic.php?f=3&t=8915
|
## How to I replace " by ' " (at the start and end of a string in a variable)? Doubling Backslashes?
Discussion forum for all Windows batch related topics.
Moderator: DosItHelp
Message
Author
pstein
Posts: 106
Joined: 09 Nov 2011 01:42
### How to I replace " by ' " (at the start and end of a string in a variable)? Doubling Backslashes?
Assume I have a variable with a double quote enclosed string inside. Most simplified by a manual assigment like
set myfile="D:\foo\bar\aaa\bbb.txt"
How can I most easily replace the two enclosing " by ' ?
How can I most easily replace the embedded single backslashes \ by double backslashes?
Afterwards the variable content should lokk like:
'D:\\foo\\bar\\aaa\\bbb.txt'
Thank you
Peter
Aacini
Expert
Posts: 1564
Joined: 06 Dec 2011 22:15
Location: México City, México
### Re: How to I replace " by ' " (at the start and end of a string in a variable)? Doubling Backslashes?
Code: Select all
for /F %%a in (%myfile:\=\\%) do set "myfile='%%a'"
If the file name may contain spaces, just add "delims=" option to the FOR /F command.
Antonio
dbenham
Expert
Posts: 2165
Joined: 12 Feb 2011 21:02
Location: United States (east coast)
### Re: How to I replace " by ' " (at the start and end of a string in a variable)? Doubling Backslashes?
The body of the question asks for a result of 'D:\\foo\\bar\\aaa\\bbb.txt', but the title implies he is looking for ' "D:\\foo\\bar\\aaa\\bbb.txt" '. (Note extra space added to differentiate between the single and double quotes)
To strip the double quotes, just modify Aacini's answer by one additional ~ character
Code: Select all
for /F "delims=" %%a in (%myfile:\=\\%) do set "myfile='%%~a'"
Assuming your string does not contain any * or ? wildcards, then you can ditch the /F option and use a simple FOR. The advantage of this is you no longer need to worry about spaces in the string:
Code: Select all
for %%a in (%myfile:\=\\%) do set "myfile='%%~a'"
Dave Benham
Squashman
Expert
Posts: 4013
Joined: 23 Dec 2011 13:59
### Re: How to I replace " by ' " (at the start and end of a string in a variable)? Doubling Backslashes?
If you have control over the code why would you assign the double quotes to the variable in the first place. That has never been a best practice on this forum.
pstein
Posts: 106
Joined: 09 Nov 2011 01:42
it works
thank you
|
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|
https://worldwidescience.org/topicpages/p/pumped+3he+laser.html
|
#### Sample records for pumped 3he laser
1. /sup 3/He functions in tokamak-pumped laser systems
Energy Technology Data Exchange (ETDEWEB)
Jassby, D.L.
1986-10-01
/sup 3/He placed in an annular cell around a tokamak fusion generator can convert moderated fusion neutrons to energetic ions by the /sup 3/He(n,p)T reaction, and thereby excite gaseous lasants mixed with the /sup 3/He while simultaneously breeding tritium. The total /sup 3/He inventory is about 4 kg for large tokamak devices. Special configurations of toroidal-field magnets, neutron moderators and beryllium reflectors are required to permit nearly uniform neutron current into the laser cell with minimal attenuation. The annular laser radiation can be combined into a single output beam at the top of the tokamak.
2. 3He functions in tokamak-pumped laser systems
International Nuclear Information System (INIS)
Jassby, D.L.
1986-10-01
3 He placed in an annular cell around a tokamak fusion generator can convert moderated fusion neutrons to energetic ions by the 3 He(n,p)T reaction, and thereby excite gaseous lasants mixed with the 3 He while simultaneously breeding tritium. The total 3 He inventory is about 4 kg for large tokamak devices. Special configurations of toroidal-field magnets, neutron moderators and beryllium reflectors are required to permit nearly uniform neutron current into the laser cell with minimal attenuation. The annular laser radiation can be combined into a single output beam at the top of the tokamak
3. Principle tests of reactor pumped laser of 3He-Ar-Xe system
International Nuclear Information System (INIS)
Chen Hande; Jin Xingxing; Yang Chengde
1994-01-01
A nuclear reactor-pumped laser was demonstrated firstly by using the 3 He(P,n) 3 H reaction to excite a 3 He-Ar-Xe laser. Lasing was observed on the 1.73 μm (5d (3/2) 1 -6p(5/2) 1 transition) in Xe I. The CAEP Pulsed Reactor (CFBR-II) was used as a source of fast neutrons moderated by a 50 mm thick polyethylene sleeve around the laser cell. A laser cell was constructed from K 9 glass tubing 600 mm long and Φ34 mm with each end cut at Brewster's angle (quartz). The laser cell was baked out to 10 -3 Pa prior to filling with research-grade mixture ( 3 He/Ar/Xe = 34.7: 34.7: 0.267 kPa). A dielectric-coated 2 m radius-curvature back mirror (99.7% reflectivity at 1.73 μm) and a flat output coupler (Φ30 mm) were used to form the optical cavity. The cavity optics were placed outside the cell as shown in Fig.3. A schematic of the experimental configuration is shown. Typical laser signals obtained with the Ge detector (-80 degree C) are also shown. Laser output lags the fast neutron pulse by the neutron thermalization time (∼278 μs). The observed light output was shown to be caused by stimulated emission, because the signal disappeared when the reflecting (flat) mirror was covered. This precludes the possibility that the phenomenon was the result of γ-radiation interaction with the detector or the air in the light path. The measured laser energy was 80 times the maximum possible fluorescence energy. The observed wavelength was measured to be 1.73 μm by using glass filters. Laser output duration was approximately 735 μs
4. Optimization of reactor power by taking into consideration temperature increase in a reactor pumped 3He-Xe laser
International Nuclear Information System (INIS)
Cetin, Fuesun
2009-01-01
In nuclear pumped lasers, gas parameters are optimized in a manner such that output power is increased for constructing a high power laser. Since output power increases with the increase of energy deposited in the gas, high output power requires high pumping power. However, the high energy loading results in elevated gas temperature. Temperature increase of this magnitude can detrimentally influence the laser gain and efficiency, since it negatively impacts several important laser kinetic.processes. This fact may cause laser output to abruptly terminate before the peak of the pump pulse [1-3]. A nuclear pumped laser using a volumetric energy source through the 3 He(n, p) 3 H reaction has here been considered. It is assumed that TRIGA Mark II Reactor at Istanbul Technical University is used for nuclear pumping as the neutron source. In the previous papers, the optimal parameters for improving both output power and optical homogeneity were determined [4-5]. Spatial and temporal variations of gas temperature during pumping pulse for maximum peak power (1200 MW) were determined for various operating pressures in Ref. [6]. It was seen that gas temperature reaches up to 1000 0 K near the peak of the pumping pulse for the initial pressures of 1-4 atm. This means that laser output may terminate before the peak of the pump pulse due to overheating of laser gas. Under these conditions, a question arises about a further optimisation taking into consideration gas temperature. This question has been examined in this study. Experimental results (Batyrbekov et al, 1989) showed that temperature rise up to 650 C had no influence on Xe laser characteristics [ 7]. Therefore, It has here been assumed that the lasing will terminate when gas temperature reaches 1000 0 K for a Xe-laser with 3 He buffer gas. Under these conditions optimum reactor power is investigated by taking into consideration lasing duration also. (orig.)
5. Spin-polarized 3He nuclear targets and metastable 4He atoms by optical pumping with a tunable, Nd:YAP laser
International Nuclear Information System (INIS)
Bohler, C.L.; Schearer, L.D.; Leduc, M.; Nacher, P.J.; Zachorowski, L.; Milner, R.G.; McKeown, R.D.; Woodward, C.E.
1988-01-01
Several Nd:YAP lasers were constructed which could be broadly tuned in the 1083-nm region which includes the helium 2 3 S-2 3 P transition, using a Lyot filter and thin, uncoated etalons within the laser cavity. 1 W of power could be extracted at 1083 nm through a 1% transmitting output coupler. This laser beam was used to optically pump metastable 4 He and 3 He 2 3 S helium atoms in a weak discharge cell, spin polarizing the metastable ensemble. In a 3 He cell the polarization is transferred to the nuclear spin system. A 3 He target cell at 0.3 Torr was polarized to 52% in a few minutes. We describe the application of this system to the design of polarized targets for experiments in nuclear physics
6. A compact spin-exchange optical pumping system for 3He polarization based on a solenoid coil, a VBG laser diode, and a cosine theta RF coil
Science.gov (United States)
Lee, Sungman; Kim, Jongyul; Moon, Myung Kook; Lee, Kye Hong; Lee, Seung Wook; Ino, Takashi; Skoy, Vadim R.; Lee, Manwoo; Kim, Guinyun
2013-02-01
For use as a neutron spin polarizer or analyzer in the neutron beam lines of the HANARO (High-flux Advanced Neutron Application ReactOr) nuclear research reactor, a 3He polarizer was designed based on both a compact solenoid coil and a VBG (volume Bragg grating) diode laser with a narrow spectral linewidth of 25 GHz. The nuclear magnetic resonance (NMR) signal was measured and analyzed using both a built-in cosine radio-frequency (RF) coil and a pick-up coil. Using a neutron transmission measurement, we estimated the polarization ratio of the 3He cell as 18% for an optical pumping time of 8 hours.
7. Studies on optical pumping cells (OPC) to polarize 3He
International Nuclear Information System (INIS)
Hutanu, V.; Rupp, A.
2004-01-01
The technique applied at HMI to obtain nuclear-spin-polarized 3 He, used in neutron spin filters (NSFs), is metastability-exchange optical pumping. To prepare efficient NSF, one must highly polarize 3 He nuclei in the optical pumping volume (OPV) and reduce the polarization losses during the compression phase. Great progress has been achieved in reducing of depolarization due to the recent development of both, large polarization preserving piston compressors and long relaxation time filter cells. It is even more important to significantly enhance the 3 He polarization rate during optical pumping in order to increase NSF efficiency. Different cells materials were tested, such as Duran and quartz glass. In order to use the laser light more efficiently and to decrease the risk of 3 He depolarization due to unfavorable reflections, antireflection (AR) coatings were used on cell windows made of quartz glass. They were compared with the ones without coating, made of quartz, Duran and BK7 glass. The comparison of various techniques to mount the windows such as blowing, gluing or molecular diffusion was also conducted. It indicated that the molecular diffusion is the most suitable technique because of a better purity of the gas in the cell and the preservation of the optical flatness of the windows. Cells, for practical reasons each entirely made from the same material (Duran, Quartz glass) with windows mounted using this method, showed the best polarization performance
8. Metastability exchange optical pumping in 3He gas up to 30 mT. Efficiency measurements and evidence of laser-induced nuclear relaxation
International Nuclear Information System (INIS)
Batz, Marion
2011-01-01
Advances in metastability exchange optical pumping (MEOP) of 3 He at high laser powers, with its various applications, but also at high gas pressures p 3 and high magnetic field strengths B, have provided strong motivation for revisiting the understanding and for investigating the limitations of this powerful technique. For this purpose, we present systematic experimental and theoretical studies of efficiency and of relaxation mechanisms in B≤30 mT and p 3 =0.63-2.45 mbar. 3 He nuclear polarisation is measured by light absorption in longitudinal configuration where weak light beams at 1083 nm parallel to magnetic field and cell axis with opposite circular polarisations are used to probe the distribution of populations in the metastable state. This method is systematically tested to evaluate potential systematic biases and is shown to be reliable for the study of OP dynamics despite the redistribution of populations by OP light. Nuclear polarisation loss associated to the emission of polarised light by the plasma discharge used for MEOP is found to decrease above 10 mT, as expected, due to hyperfine decoupling in highly excited states. However, this does not lead to improved MEOP efficiency at high laser power. We find clear evidence of additional laser-induced relaxation instead. The strong OP-enhanced polarisation losses, currently limiting MEOP performances, are quantitatively investigated using an angular momentum budget approach and a recently developed comprehensive model that describes the combined effects of OP, ME and relaxation, validated by comparison to experimental results.
9. Metastability exchange optical pumping in {sup 3}He gas up to 30 mT. Efficiency measurements and evidence of laser-induced nuclear relaxation
Energy Technology Data Exchange (ETDEWEB)
Batz, Marion
2011-07-08
Advances in metastability exchange optical pumping (MEOP) of {sup 3}He at high laser powers, with its various applications, but also at high gas pressures p{sub 3} and high magnetic field strengths B, have provided strong motivation for revisiting the understanding and for investigating the limitations of this powerful technique. For this purpose, we present systematic experimental and theoretical studies of efficiency and of relaxation mechanisms in B{<=}30 mT and p{sub 3}=0.63-2.45 mbar. {sup 3}He nuclear polarisation is measured by light absorption in longitudinal configuration where weak light beams at 1083 nm parallel to magnetic field and cell axis with opposite circular polarisations are used to probe the distribution of populations in the metastable state. This method is systematically tested to evaluate potential systematic biases and is shown to be reliable for the study of OP dynamics despite the redistribution of populations by OP light. Nuclear polarisation loss associated to the emission of polarised light by the plasma discharge used for MEOP is found to decrease above 10 mT, as expected, due to hyperfine decoupling in highly excited states. However, this does not lead to improved MEOP efficiency at high laser power. We find clear evidence of additional laser-induced relaxation instead. The strong OP-enhanced polarisation losses, currently limiting MEOP performances, are quantitatively investigated using an angular momentum budget approach and a recently developed comprehensive model that describes the combined effects of OP, ME and relaxation, validated by comparison to experimental results.
10. Increasing the pump-up rate to polarize 3He gas using spin-exchange optical pumping method
International Nuclear Information System (INIS)
Lee, W.T.; Tong Xin; Rich, Dennis; Liu Yun; Fleenor, Michael; Ismaili, Akbar; Pierce, Joshua; Hagen, Mark; Dadras, Jonny; Robertson, J. Lee
2009-01-01
In recent years, polarized 3 He gas has increasingly been used as neutron polarizers and polarization analyzers. Two of the leading methods to polarize the 3 He gas are the spin-exchange optical pumping (SEOP) method and the meta-stable exchange optical pumping (MEOP) method. At present, the SEOP setup is comparatively compact due to the fact that it does not require the sophisticated compressor system used in the MEOP method. The temperature and the laser power available determine the speed, at which the SEOP method polarizes the 3 He gas. For the quantity of gas typically used in neutron scattering work, this speed is independent of the quantity of the gas required, whereas the polarizing time using the MEOP method is proportional to the quantity of gas required. Currently, using the SEOP method to polarize several bar-liters of 3 He to 70% polarization would require 20-40 h. This is an order of magnitude longer than the MEOP method for the same quantity of gas and polarization. It would therefore be advantageous to speed up the SEOP process. In this article, we analyze the requirements for temperature, laser power, and the type of alkali used in order to shorten the time required to polarize 3 He gas using the SEOP method.
11. Production of highly polarized 3He using spectrally narrowed diode laser array bars
International Nuclear Information System (INIS)
Chann, B.; Babcock, E.; Anderson, L.W.; Walker, T.G.; Chen, W.C.; Smith, T.B.; Thompson, A.K.; Gentile, T.R.
2003-01-01
We have produced 70%-75% 3 He polarization by spin-exchange optical pumping in cells ≅100 cm 3 in volume. The polarization achieved is consistent with known spin-exchange and spin-relaxation rates, but only when the recently discovered temperature dependence of 3 He relaxation is included. Absolute 3 He polarization measurements were performed using two different methods in two different laboratories. The results were obtained with either a spectrally narrowed laser or one type of broadband laser. Based on tests of several larger cells at pressures near 1 bar, we find that the power required to reach the same polarization is typically three times lower for the spectrally narrowed laser. This last result indicates that spectrally narrowed lasers will be important for obtaining the highest polarization in large volume neutron spin filters. Polarization in excess of 55% as obtained in cells up to 640 cm 3 in volume and 70% polarization is anticipated with available increases in spectrally narrowed laser power
12. Metastability-exchange optical pumping of 3He for neutron polarizers
International Nuclear Information System (INIS)
Gentile, T.R.; Thompson, A.K.; Snow, W.M.
1995-01-01
Research is underway at NIST and IU to develop neutron polarizers that are based on polarized 3 He. Such polarizers rely on the strong spin dependence of the cross section for neutron capture by polarized 3 He. Two methods can produce the high density of polarized 3 He gas (10 19 -10 20 cm -3 ) required for an effective neutron polarizer: spin-exchange optical pumping, which is performed directly at high pressure (1-10 bar), and metastability-exchange optical pumping, in which the gas is polarized at low pressure (1 mbar) and then compressed. While we are pursuing both methods, progress in the metastable method will be discussed. The features of the metastable method are the high rate at which the gas can be polarized and the inherent separation of the optical pumping and target cells. In a landmark achievement, researchers at the Univ. of Mainz have developed a piston compressor that can fill a 130 cm 3 cell to a pressure of 7 bar of 45% polarized 3 He gas in 2 hours. We plan to develop a compressor and test it at the NIST Cold Neutron Research Facility. We have constructed a metastable-pumping apparatus at NIST and have obtained 76% polarization with a pumping rate of 1.2 x 10 18 atoms/sec in a 0.4 mbar, 270 cm 3 cell
13. Optical Pumping Spin Exchange 3He Gas Cells for Magnetic Resonance Imaging
Science.gov (United States)
Kim, W.; Stepanyan, S. S.; Kim, A.; Jung, Y.; Woo, S.; Yurov, M.; Jang, J.
2009-08-01
We present a device for spin-exchange optical pumping system to produce large quantities of polarized noble gases for Magnetic Resonance Imaging (MRI). A method and design of apparatus for pumping the polarization of noble gases is described. The method and apparatus enable production, storage and usage of hyperpolarized noble gases for different purposes, including Magnetic Resonance Imaging of human and animal subjects. Magnetic imaging agents breathed into lungs can be observed by the radio waves of the MRI scanner and report back physical and functional information about lung's health and desease. The technique known as spin exchange optical pumping is used. Nuclear magnetic resonance is implemented to measure the polarization of hyperpolarized gas. The cells prepared and sealed under high vacuum after handling Alkali metals into the cell and filling with the 3He-N2 mixture. The cells could be refilled. The 3He reaches around 50% polarization in 5-15 hours.
14. Recent Spin Pump Experiments on Superfluid 3He-A1
Science.gov (United States)
Yamaguchi, A.; Kamada, N.; Motoyama, G.; Sumiyama, A.; Aoki, Y.; Okuda, Y.; Kubota, M.; Kojima, H.
2013-05-01
The superfluid 3He A1 phase, containing a spin-polarized condensate allows us to explore the dynamics of superfluid spin current. In the mechano-spin effect (MSE), a mechanically applied pressure gradient and a superleak-spin filter enable one to directly boost spin polarization of 3He in a small chamber. We are developing new apparatus for achieving greater enhancement of spin density. A development of a new-type 3He-hydraulic actuator has been already reported. We present here the construction of new-type of superleak-spin-filter made of packed powder aluminum oxide (referred as PAP-SL). The PAP-SL is popular in the study of superfluid 4He, but has not been established for that of the superfluid 3He. The attempt to construct the PAP-SL for the spin pump experiment was made by using aluminum oxide powder with nominal 1 μm powder diameter and with packing fraction of 40 %. Before executing the experiment, the nuclear demagnetization cryostat of ISSP, Univ. Tokyo which has been used for this experimental activity, was heavily damaged by the 2011 Great East Japan (Higashi Nihon) Earthquake. The repair work and earthquake damage protection strengthening has just been accomplished.
15. Spin exchange optical pumping based polarized 3He filling station for the Hybrid Spectrometer at the Spallation Neutron Source.
Science.gov (United States)
Jiang, C Y; Tong, X; Brown, D R; Culbertson, H; Graves-Brook, M K; Hagen, M E; Kadron, B; Lee, W T; Robertson, J L; Winn, B
2013-06-01
The Hybrid Spectrometer (HYSPEC) is a new direct geometry spectrometer at the Spallation Neutron Source at the Oak Ridge National Laboratory. This instrument is equipped with polarization analysis capability with 60° horizontal and 15° vertical detector coverages. In order to provide wide angle polarization analysis for this instrument, we have designed and built a novel polarized (3)He filling station based on the spin exchange optical pumping method. It is designed to supply polarized (3)He gas to HYSPEC as a neutron polarization analyzer. In addition, the station can optimize the (3)He pressure with respect to the scattered neutron energies. The depolarized (3)He gas in the analyzer can be transferred back to the station to be repolarized. We have constructed the prototype filling station. Preliminary tests have been carried out demonstrating the feasibility of the filling station. Here, we report on the design, construction, and the preliminary results of the prototype filling station.
16. A measurement of the absolute neutron beam polarization produced by an optically pumped 3He neutron spin filter
International Nuclear Information System (INIS)
Rich, D.R.; Bowman, J.D.; Crawford, B.E.; Delheij, P.P.J.; Espy, M.A.; Haseyama, T.; Jones, G.; Keith, C.D.; Knudson, J.; Leuschner, M.B.; Masaike, A.; Masuda, Y.; Matsuda, Y.; Penttilae, S.I.; Pomeroy, V.R.; Smith, D.A.; Snow, W.M.; Szymanski, J.J.; Stephenson, S.L.; Thompson, A.K.; Yuan, V.
2002-01-01
The capability of performing accurate absolute measurements of neutron beam polarization opens a number of exciting opportunities in fundamental neutron physics and in neutron scattering. At the LANSCE pulsed neutron source we have measured the neutron beam polarization with an absolute accuracy of 0.3% in the neutron energy range from 40 meV to 10 eV using an optically pumped polarized 3 He spin filter and a relative transmission measurement technique. 3 He was polarized using the Rb spin-exchange method. We describe the measurement technique, present our results, and discuss some of the systematic effects associated with the method
17. Numerical simulation for nuclear pumped laser
Energy Technology Data Exchange (ETDEWEB)
Sakasai, Kaoru [Japan Atomic Energy Research Inst., Tokyo (Japan)
1998-07-01
To apply nuclear pumped laser of {sup 3}He-Ne-Ar gas to detect neutron, the optimum gas mixture was investigated by numerical simulation. When {sup 3}He-Ne-Ar mixture gas are irradiated by neutron, proton and triton with high velocity are produced by {sup 3}He(np)T and two charge particles ionized {sup 3}He, Ne and Ar which reacted each other and attained to 3p(1/2){sub 0}-3S(1/2). The calculation method is constructed by defining the rate equations of each ion and exited atom and the electron energy balance equation and by time integrating the simultaneous differential equations of the above two equations and the law of conservation of charge. Penning ionization and energy transport by elastic collision of neutral atom were considered in the transport process of electron energy direct ionization by secondary charge particle. Calculation time was 1 msec. The optimum component was shown 3 atm He, 24 Torr He and 8 Torr Ar by simulation. Laser oscilation was generated under the conditions 3.3 x 10{sup 14} (N/cm{sup 2}/5) thermal neutron flux at 50 cm laser cell length and 99% coefficient of reflection of mirror. After laser oscilation, laser output was proportional to neutron flux. These results showed nuclear pumped laser of {sup 3}He-Ne-Ar was able to detect optically neutron. (S.Y)
18. Nuclear-pumped lasers
CERN Document Server
Prelas, Mark
2016-01-01
This book focuses on Nuclear-Pumped Laser (NPL) technology and provides the reader with a fundamental understanding of NPLs, a review of research in the field, and exploration of large scale NPL system design and applications. Early chapters look at the fundamental properties of lasers, nuclear-pumping and nuclear reactions that may be used as drivers for nuclear-pumped lasers. The book goes on to explore the efficient transport of energy from the ionizing radiation to the laser medium and then the operational characteristics of existing nuclear-pumped lasers. Models based on Mathematica, explanations and a tutorial all assist the reader’s understanding of this technology. Later chapters consider the integration of the various systems involved in NPLs and the ways in which they can be used, including beyond the military agenda. As readers will discover, there are significant humanitarian applications for high energy/power lasers, such as deflecting asteroids, space propulsion, power transmission and mining....
19. Solar pumped laser
Science.gov (United States)
Lee, J. H.; Hohl, F.; Weaver, W. R. (Inventor)
1984-01-01
A solar pumped laser is described in which the lasant is a gas that will photodissociate and lase when subjected to sunrays. Sunrays are collected and directed onto the gas lasant to cause it to lase. Applications to laser propulsion and laser power transmission are discussed.
20. Fusion reactor pumped laser
International Nuclear Information System (INIS)
Jassby, D.L.
1988-01-01
A nuclear pumped laser is described comprising: a toroidal fusion reactor, the reactor generating energetic neutrons; an annular gas cell disposed around the outer periphery of the reactor, the cell including an annular reflecting mirror disposed at the bottom of the cell and an annular output window disposed at the top of the cell; a gas lasing medium disposed within the annular cell for generating output laser radiation; neutron reflector material means disposed around the annular cell for reflecting neutrons incident thereon back into the gas cell; neutron moderator material means disposed between the reactor and the gas cell and between the gas cell and the neutron reflector material for moderating the energy of energetic neutrons from the reactor; converting means for converting energy from the moderated neutrons to energy pumping means for pumping the gas lasing medium; and beam compactor means for receiving output laser radiation from the annular output window and generating a single output laser beam therefrom
1. Optically pumped laser systems
International Nuclear Information System (INIS)
DeMaria, A.J.; Mack, M.E.
1975-01-01
Laser systems which are pumped by an electric discharge formed in a gas are disclosed. The discharge is in the form of a vortex stabilized electric arc which is triggered with an auxiliary energy source. At high enough repetition rates residual ionization between successive pulses contributes to the pulse stabilization. The arc and the gain medium are positioned inside an optical pumping cavity where light from the arc is coupled directly into the gain medium
2. Diode laser pumping
International Nuclear Information System (INIS)
Skagerlund, L.E.
1975-01-01
A diode laser is pumped or pulsed by a repeated capacitive discharge. A capacitor is periodically charged from a dc voltage source via a transformer, the capacitor being discharged through the diode laser via a controlled switching means after one or more charging periods. During a first interval of each charging period the transformer, while unloaded, stores a specific amount of energy supplied from the dc voltage source. During a subsequent interval of the charging period said specific amount of energy is transmitted from the transformer to the capacitor. The discharging of the capacitor takes place during a first interval of a charging period. (auth)
3. Direct solar-pumped lasers
Science.gov (United States)
Lee, J. H.; Shiu, Y. J.; Weaver, W. R.
1980-01-01
The feasibility of direct solar pumping of an iodine photodissociation laser at lambda = 1.315 microns was investigated. Threshold inversion density and effect of elevated temperature (up to 670 K) on the laser output were measured. These results and the concentration of solar radiation required for the solar pumped iodine laser are discussed.
4. Uses of laser optical pumping to produce polarized ion beams
International Nuclear Information System (INIS)
Anderson, L.W.
1983-01-01
Laser optical pumping can be used to produce polarized alkali atom beams or polarized alkali vapor targets. Polarized alkali atom beams can be converted into polarized alkali ion beams, and polarized alkali vapor targets can be used to produce polarized H - or 3 He - ion beams. In this paper the authors discuss how the polarized alkali atom beams and polarized alkali vapor targets are used to produce polarized ion beams with emphasis on the production of polarized negative ion beams
5. Development of polarized {sup 3}He filter for polarized neutron experiment
Energy Technology Data Exchange (ETDEWEB)
Sakai, K.; Sato, H.; Yoshimi, A.; Asahi, K. [Tokyo Inst. of Tech. (Japan). Faculty of Science; Masuda, Y.; Muto, S.; Ishimoto, S.; Morimoto, K.
1996-08-01
A high-pressure polarized {sup 3}He gas cell, pumped with two diode lasers, has been developed at KEK for use as a polarizer and a spin analyzer for low energy neutrons. The polarization attained of {sup 3}He was determined through the measurement of the transmission of the unpolarized neutrons through the {sup 3}He cell. So far we obtained P{sub He}=18% at 10 atm and P{sub He}=12% at 20 atm. (author)
6. Laser pumped lasers for isotope separation
International Nuclear Information System (INIS)
Fry, S.M.
1976-01-01
A study of the isotope separation laser requirements reveals that high pressure polyatomic molecular gas laser pumped lasers can attain the necessary characteristics including tunability, energy output, pulse width, and repetition rate. The results of a search, made for molecules meeting the appropriate requirements for one of several pump schemes utilizing a CO 2 laser and with output in the 12 μm or 16μm wavelength range, are presented. Several methods of pumping are reviewed and two novel pump schemes are presented. A laser pumped laser device design is given, and operation of this device and associated diagnostic equipment is confirmed by repeating experiments in OCS and NH 3 . The results of OCS laser experiments show that an improvement in pump rate and output per unit length is obtained with the device, using a wedged transverse pumping scheme. A new multi-line laser system in NH 3 pumped by a TEA CO 2 laser is reported. More than forty transitions spanning the wavelength range of 9.2 to 13.8 μm are observed and identified. A strong output at 12.08 μm is one of the closest lines yet found to the required laser isotope separation wavelength. Far infrared emission near 65 μm is observed and is responsible for populating levels which lase in pure ammonia near 12.3 μm. Buffer gas (e.g., N 2 or He) pressures of approximately 40--800 torr cause energy transfer by collision-induced rotationaltransitions from the pumped antisymmetric to the lasing symmetric levels in the nu 2 = 1 band of ammonia. Most of the observed lines are aP(J,K) transitions which originate from the nu 2 /sup s/ band. Measurements of the pressure dependence of the laser output shows that some lines lase at pressures greater than one atmosphere. Transient behavior of the 12.08 μm line is calculated from a simplified analytic model and these calculations are compared to the experimental results
7. Transverse pumped laser amplifier architecture
Science.gov (United States)
Bayramian, Andrew James; Manes, Kenneth; Deri, Robert; Erlandson, Al; Caird, John; Spaeth, Mary
2013-07-09
An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.
8. A longitudinally-pumped laser (specifically, pulse-pumped lasers)
Energy Technology Data Exchange (ETDEWEB)
Wojtkowiak, J
1979-10-15
A laser is proposed that employs travelling-wave pumping, for which no less than four electrodes, interconnected with coaxial transmission lines with a feed network, are placed at specific distances from each other in a discharge channel filled with an active medium. An expression is given for determining the length of the coaxial sections.
9. Cost Effective, Scalable Optically Pumped Molecular Laser
National Research Council Canada - National Science Library
Nicholson, Jeff
2001-01-01
An optically pumped, For laser was demonstrated operating at 4.0 micrometers. This is the first demonstration of an HBr laser by direct optical pumping of the 0 right arrow 3 vibrational overtone band at 1.34 micrometers...
10. Compact and highly efficient laser pump cavity
Science.gov (United States)
Chang, Jim J.; Bass, Isaac L.; Zapata, Luis E.
1999-01-01
A new, compact, side-pumped laser pump cavity design which uses non-conventional optics for injection of laser-diode light into a laser pump chamber includes a plurality of elongated light concentration channels. In one embodiment, the light concentration channels are compound parabolic concentrators (CPC) which have very small exit apertures so that light will not escape from the pumping chamber and will be multiply reflected through the laser rod. This new design effectively traps the pump radiation inside the pump chamber that encloses the laser rod. It enables more uniform laser pumping and highly effective recycle of pump radiation, leading to significantly improved laser performance. This new design also effectively widens the acceptable radiation wavelength of the diodes, resulting in a more reliable laser performance with lower cost.
11. Thermometry in 3He
International Nuclear Information System (INIS)
Richardson, R.C.
1977-01-01
Some of the methods used in measuring the temperatures of the transitions in 3 He are reviewed. Although noise thermometers, γ-ray anisotropy thermometers and even Pt NMR thermometers are satisfactory for furnishing temperature standards, they are not satisfactory secondary thermometers. The susceptibility of CMN and various 3 He properties make more precise and quicker thermometric indications. (Auth.)
12. Simulations of longitudinally pumped dye laser amplifier
International Nuclear Information System (INIS)
Takehisa, Kiwamu; Takemori, Satoshi
1995-01-01
Simulations of a copper laser pumped dye laser amplifier and new designs of the longitudinally pumped dye laser amplifier are presented. The simulations take the consideration of the amplified spontaneous emission (ASE). The new designs utilize a center-hole reflector instead of a dichroic mirror. The simulation results indicate that the poor spatial overlap between the pump beam and the dye beam in the transverse pumping not only reduces the laser output power, but also generates ASE strongly. The results also indicate that the longitudinal pumping is as efficient as the transverse pumping. (author)
13. Fusion pumped laser
Science.gov (United States)
Pappas, D.S.
1987-07-31
The apparatus of this invention may comprise a system for generating laser radiation from a high-energy neutron source. The neutron source is a tokamak fusion reactor generating a long pulse of high-energy neutrons and having a temperature and magnetic field effective to generate a neutron flux of at least 10/sup 15/ neutrons/cm/sup 2//center dot/s. Conversion means are provided adjacent the fusion reactor at a location operable for converting the high-energy neutrons to an energy source with an intensity and energy effective to excite a preselected lasing medium. A lasing medium is spaced about and responsive to the energy source to generate a population inversion effective to support laser oscillations for generating output radiation. 2 figs., 2 tabs.
14. Diode-pumped laser with improved pumping system
Science.gov (United States)
Chang, Jim J.
2004-03-09
A laser wherein pump radiation from laser diodes is delivered to a pump chamber and into the lasing medium by quasi-three-dimensional compound parabolic concentrator light channels. The light channels have reflective side walls with a curved surface and reflective end walls with a curved surface. A flow tube between the lasing medium and the light channel has a roughened surface.
15. Polarized (3) He Spin Filters for Slow Neutron Physics.
Science.gov (United States)
Gentile, T R; Chen, W C; Jones, G L; Babcock, E; Walker, T G
2005-01-01
Polarized (3)He spin filters are needed for a variety of experiments with slow neutrons. Their demonstrated utility for highly accurate determination of neutron polarization are critical to the next generation of betadecay correlation coefficient measurements. In addition, they are broadband devices that can polarize large area and high divergence neutron beams with little gamma-ray background, and allow for an additional spin-flip for systematic tests. These attributes are relevant to all neutron sources, but are particularly well-matched to time of flight analysis at spallation sources. There are several issues in the practical use of (3)He spin filters for slow neutron physics. Besides the essential goal of maximizing the (3)He polarization, we also seek to decrease the constraints on cell lifetimes and magnetic field homogeneity. In addition, cells with highly uniform gas thickness are required to produce the spatially uniform neutron polarization needed for beta-decay correlation coefficient experiments. We are currently employing spin-exchange (SE) and metastability-exchange (ME) optical pumping to polarize (3)He, but will focus on SE. We will discuss the recent demonstration of 75 % (3)He polarization, temperature-dependent relaxation mechanism of unknown origin, cell development, spectrally narrowed lasers, and hybrid spin-exchange optical pumping.
16. Laser Diode Pumped Solid State Lasers
Science.gov (United States)
1987-01-01
Report N66001-83-C-0071, 17 April 1986, prepared for NOSC. 4.6 W.T. Welford, R. Winston , "The Option of Nonimaging Concentrators ," Academic Press, 1978...by non-imac optics such as reflective or refractive flux concentrators . Simple considerations regarding the optimum pumping configuration, high marks...reduced if the arrays can stand-off from the Nd:YAG laser. As mentioned before, compound parabolic concentrators or refractive optics cat employed to
17. High power diode pumped solid state lasers
International Nuclear Information System (INIS)
Solarz, R.; Albrecht, G.; Beach, R.; Comaskey, B.
1992-01-01
Although operational for over twenty years, diode pumped solid state lasers have, for most of their existence, been limited to individual diodes pumping a tiny volume of active medium in an end pumped configuration. More recent years have witnessed the appearance of diode bars, packing around 100 diodes in a 1 cm bar which have enabled end and side pumped small solid state lasers at the few Watt level of output. This paper describes the subsequent development of how proper cooling and stacking of bars enables the fabrication of multi kill average power diode pump arrays with irradiances of 1 kw/cm peak and 250 W/cm 2 average pump power. Since typical conversion efficiencies from the diode light to the pumped laser output light are of order 30% or more, kW average power diode pumped solid state lasers now are possible
18. Nuclear-driven flashlamp pumping of the atomic iodine laser
International Nuclear Information System (INIS)
Miley, G.H.
1992-03-01
This report is a study of the atomic iodine laser pumped with nuclear- excited XeBr fluorescence. Preliminary experiments, conducted in the TRIGA reactor investigated the fluorescence of the excimer XeBr under nuclear pumping with 10 B and 3 He, for use as a flashlamp gas to stimulate the laser. These measurements included a determination of the fluorescence efficiency (light emitted in the wavelength region of interest, divided by energy deposited in the gas) of XeBr under nuclear pumping, with varying excimer mixtures. Maximum fluorescence efficiencies were approximately 1%. In order to better understand XeBr under nuclear excitation, a kinetics model of the system was prepared. The model generated the time-dependant concentrations of 20 reaction species for three pulse sizes, a TRIGA pulse, a fast burst reactor pulse, and an e-beam pulse. The modeling results predicted fluorescence efficiencies significantly higher (peak efficiencies of approximately 10%) than recorded in the fluorescence experiments. The cause of this discrepancy was not fully determined. A ray tracing computer model was also prepared to evaluate the efficiency with which nuclear-induced fluorescence generated in one cavity of a laser could be coupled into another cavity containing an iodine lasant. Finally, an experimental laser cell was constructed to verify that nuclear-induced XeBr fluorescence could be used to stimulate a laser. Lasing was achieved at 1.31 micron in the TRIGA using C 3 F 7 I, a common iodine lasant. Peak laser powers were approximately 20 mW. Measured flashlamp pump powers at threshold agreed well with literature values, as did lasant pressure dependency on laser operation
19. Solar-pumped solid state Nd lasers
Science.gov (United States)
Williams, M. D.; Zapata, L.
1985-01-01
Solid state neodymium lasers are considered candidates for space-based polar-pumped laser for continuous power transmission. Laser performance for three different slab laser configurations has been computed to show the excellent power capability of such systems if heat problems can be solved. Ideas involving geometries and materials are offered as potential solutions to the heat problem.
20. Cladding For Transversely-Pumped Laser Rod
Science.gov (United States)
Byer, Robert L.; Fan, Tso Yee
1989-01-01
Combination of suitable dimensioning and cladding of neodymium:yttrium aluminum garnet of similar solid-state laser provides for more efficient utilization of transversely-incident pump light from diode lasers. New design overcomes some of limitations of longitudinal- and older transverse-pumping concepts and promotes operation at higher output powers in TEM00 mode.
1. Direct solar-pumped iodine laser amplifier
Science.gov (United States)
Han, Kwang S.; Hwang, In Heon
1990-01-01
The optimum conditions of a solar pumped iodine laser are found in this research for the case of a continuous wave operation and a pulsed operation. The optimum product of the pressure(p) inside the laser tube and the tube diameter(d) was pd=40 approx. 50 torr-cm on the contrary to the case of a high intensity flashlamp pumped iodine laser where the optimum value of the product is known to be pd=150 torr-cm. The pressure-diameter product is less than 1/3 of that of the high power iodine laser. During the research period, various laser materials were also studied for solar pumping. Among the laser materials, Nd:YAG is found to have the lowest laser threshold pumping intensity of about 200 solar constant. The Rhodamine 6G was also tested as the solar pumped laser material. The threshold pumping power was measured to be about 20,000 solar constant. The amplification experiment for a continuously pumped iodine laser amplifier was performed using Vortek solar simulator and the amplification factors were measured for single pass amplification and triple pass amplification of the 15 cm long amplifier tube. The amplification of 5 was obtained for the triple pass amplification.
2. Feasibility of solar-pumped dye lasers
Science.gov (United States)
Lee, Ja H.; Kim, Kyung C.; Kim, Kyong H.
1987-01-01
Dye laser gains were measured at various pump-beam irradiances on a dye cell in order to evaluate the feasibility of solar pumping. Rhodamine 6G dye was considered as a candidate for the solar-pumped laser because of its high utilization of the solar spectrum and high quantum efficiency. Measurements show that a solar concentration of 20,000 is required to reach the threshold of the dye.
3. Theoretcial studies of solar-pumped lasers
Science.gov (United States)
Harries, W. L.; Fong, Z. S.
1984-01-01
A method of pumping a COhZ laser by a hot cavity was demonstrated. The cavity, heated by solar radiation, should increase the efficiency of solar pumped lasers used for energy conversion. Kinetic modeling is used to examine the behavior of such a COhZ laser. The kinetic equations are solved numerically vs. time and, in addition, steady state solutions are obtained analytically. The effect of gas heating filling the lower laser level is included. The output power and laser efficiency are obtained as functions of black body temperature and gas ratios (COhZ-He-Ar) and pressures. The values are compared with experimental results.
4. Direct solar-pumped iodine laser amplifier
Science.gov (United States)
Han, Kwang S.
1987-01-01
This semiannual progress report covers the period from March 1, 1987 to September 30, 1987 under NASA grant NAG1-441 entitled 'Direct solar-pumped iodine laser amplifier'. During this period Nd:YAG and Nd:Cr:GSGG crystals have been tested for the solar-simulator pumped cw laser, and loss mechanisms of the laser output power in a flashlamp-pumped iodine laser also have been identified theoretically. It was observed that the threshold pump-beam intensities for both Nd:YAG and Nd:Cr:GSGG crystals were about 1000 solar constants, and the cw laser operation of the Nd:Cr:GSGG crystal was more difficult than that of the Nd:YAG crystal under the solar-simulator pumping. The possibility of the Nd:Cr:GSGG laser operation with a fast continuously chopped pumping was also observed. In addition, good agreement between the theoretical calculations and the experimental data on the loss mechanisms of a flashlamp-pumped iodine laser at various fill pressures and various lasants was achieved.
5. Tapered diode laser pumped 946 nm Nd:YAG laser
DEFF Research Database (Denmark)
Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Petersen, Paul Michael
2009-01-01
We successfully implemented a 946 nm Nd:YAG laser based on a 808 nm tapered diode pump laser. The tapered diode is developed at the Ferdinand-Braun-Institute fur Hochstfrequenztechnik in Germany. Figure 2 shows the experimental setup and results of each pump source coupled into a 1.5 mm crystal...... laser, we show that tapered diode laser pumping potentially increase the power of 946 nm lasers by a factor of two and reduce the threshold by a factor of three....
6. Status of Nuclear-Pumped Laser research
International Nuclear Information System (INIS)
Prelas, M.A.
1984-01-01
The field of Nuclear-Pumped lasers (NPLs) has progressed in many directions since the discovery of the first NPL in 1974. This paper discusses developments in the area of coupling nuclear energy to a laser media, kinetics, and the integration of nuclear reactors to a laser (or other types of energy conversion medium). Many questions about the process of nuclear-pumping have been examined since the discovery of the first NPL in 1974. During a period of time between 1974 and 1981, several types of lasers have been driven by nuclear reactions (ie rare gas lasers, impurity type lasers, molecular lasers, and an ion laser). Three of the lasers discovered, had demonstrated efficiencies of >1%. In addition, volume scaling of NPLs was demonstrated
7. Ho:YLF pumped HBr laser
CSIR Research Space (South Africa)
Botha, LR
2009-10-01
Full Text Available , “Optically Pumped Mid-Infrared HBr Laser,” IEEE J. Quantum Electron. 30(10), 2395–2400 (1994). 2. C. S. Kletecka, N. Campbell, C. R. Jones, J. W. Nicolson, and W. Rudolph, “Cascade Lasing of Molecular HBr in the Four Micron Region Pumped by a Nd:YAG laser...-Infrared Coherent Sources, (European Physical Society 2009) Invited Talk Mo3. 5. C. Bollig, H. J. Strauss, M. J. D. Esser, W. Koen, M.Schellhorn, D. Preussler, K. Nyangaza, C. Jacobs, E. H. Bernardi and L. R. Botha, “Compact Fibre-Laser-Pumped Ho:YLF Oscillator...
8. Research on solar pumped liquid lasers
Science.gov (United States)
Schneider, R. T.; Kurzweg, U. H.; Cox, J. D.; Weinstein, N. H.
1983-01-01
A solar pumped liquid laser that can be scaled up to high power (10Mw CW) for space applications was developed. Liquid lasers have the inherent advantage over gases in that they provide much higher lasant densities and thus high power densities. Liquids also have inherent advantages over solids in that they have much higher damage thresholds and are much cheaper to produce for large scale applications. Among the liquid laser media that are potential candidates for solar pumping, the POC13:Nd(3+):ZrC14 liquid was chosen for its high intrinsic efficiency as well as its relatively good stability against decomposition due to protic contamination. The development and testing of the laser liquid and the development of a large solar concentrator to pump the laser was emphasized. The procedure to manufacture the laser liquid must include diagnostic tests of the solvent purity (from protic contamination) at various stages in the production process.
9. Compact electron accelerator for pumping gas lasers
International Nuclear Information System (INIS)
1976-01-01
A description is given of the design and application of a simple e-beam generator for the repetitive pulse pumping of gas lasers. The circuit uses a low inductance Marx and series tuned pulse forming elements
10. Exploding conducting film laser pumping apparatus
Science.gov (United States)
Ware, K.D.; Jones, C.R.
1984-04-27
The 342-nm molecular iodine and the 1.315-..mu..m atomic iodine lasers have been optically pumped by intense light from exploding-metal-film discharges. Brightness temperatures for the exploding-film discharges were approximately 25,000 K. Although lower output energies were achieved for such discharges when compared to exploding-wire techniques, the larger surface area and smaller inductance inherent in the exploding-film should lead to improved efficiency for optically-pumped gas lasers.
11. Research on solar pumped liquid lasers
Science.gov (United States)
Cox, J. D.; Kurzweg, U. H.; Weinstein, N. H.; Schneider, R. T.
1985-01-01
A solar pumped liquid laser that can be scaled up to high power (10 mW CW) for space applications was developed. Liquid lasers have the advantage over gases in that they provide much higher lasant densities and thus high-power densities. Liquids also have advantages over solids in that they have much higher damage thresholds and are much cheaper to produce for large scale applications. Among the liquid laser media that are potential candidates for solar pumping, the POC13: Nd sup 3+:ZrC14 liquid was chosen for its high intrinsic efficiency and its relatively good stability against decomposition due to protic contamination. The development of a manufacturing procedure and performance testing of the laser, liquid and the development of an inexpensive large solar concentrator to pump the laser are examined.
12. Radiative characteristics of CVL pumped dye laser
Energy Technology Data Exchange (ETDEWEB)
Kubo, Uichi; Ishiguro, Takahide
1987-09-01
This paper describes the radiative characteristics of CVL pumped dye laser. It is compared YAG-SH (530 nm) with CVL (511, 578 nm) and CVL (511 nm) for pumping source. Influence of solvent in dye laser power was examined. The present experimental results show that efficiency of CVL (511 nm) pumped dye laser was most high. When the dye solution is at a standstill, the efficiency of dye laser with water and Sodium Lauryl Sulfate (S.L.S., 2 %wt.) was most high among the four kinds of solvent. In the condition of dye solution flow, the water and S.L.S. or ethylene glycol was useful solvent for dye laser.
13. Radiative characteristics of CVL pumped dye laser
International Nuclear Information System (INIS)
Kubo, Uichi; Ishiguro, Takahide.
1987-01-01
This paper describes the radiative characteristics of CVL pumped dye laser. It is compared YAG-SH (530 nm) with CVL (511, 578 nm) and CVL (511 nm) for pumping source. Influence of solvent in dye laser power was examined. The present experimental results show that efficiency of CVL (511 nm) pumped dye laser was most high. When the dye solution is at a standstill, the efficiency of dye laser with water and Sodium Lauryl Sulfate (S.L.S., 2 %wt.) was most high among the four kinds of solvent. In the condition of dye solution flow, the water and S.L.S. or Ethylene Glycol was useful solvent for dye laser. (author)
14. Tunable diode-pumped-LNA laser
International Nuclear Information System (INIS)
Cassimi, A.; Hardy, V.; Hamel, J.; Leduc, M.
1987-01-01
Diode-pumped crystals provided recently new compact laser devices. We report the first end pumping of a La x Nd 1-x MgAl 11 O 19 (LNA) crystal using a 200mW diode array (Spectra Diode Lab). We also report the first results obtained with a 1mW diode (SONY). This C.W. laser can be tuned from 1.048μm to 1.086μm. Without selective elements in the cavity, the laser emits around 1.054μm with a threshold of 24mW and a slope efficiency of 4.4% (output mirror of transmission T = 1%) when pumped by the diode array. With the selective elements, the threshold increases to 100mW and we obtain a power of 4mW for a pump power of 200mW
15. Depletion mode pumping of solid state lasers
International Nuclear Information System (INIS)
Mundinger, D.; Solarz, R.; Beach, R.; Albrecht, G.; Krupke, W.
1990-01-01
Depletion mode pumping of solid state lasers is a new concept which offers features that are of interest for many practical applications. In this paper the authors discuss the physical properties and mechanisms that set the design requirements, present model calculations for a practical laser design, and discuss the results of recent experiments
16. Development of high-performance alkali-hybrid polarized 3He targets for electron scattering
Science.gov (United States)
Singh, Jaideep T.; Dolph, P. A. M.; Tobias, W. A.; Averett, T. D.; Kelleher, A.; Mooney, K. E.; Nelyubin, V. V.; Wang, Yunxiao; Zheng, Yuan; Cates, G. D.
2015-05-01
Background: Polarized 3He targets have been used as effective polarized neutron targets for electron scattering experiments for over twenty years. Over the last ten years, the effective luminosity of polarized 3He targets based on spin-exchange optical pumping has increased by over an order of magnitude. This has come about because of improvements in commercially-available lasers and an improved understanding of the physics behind the polarization process. Purpose: We present the development of high-performance polarized 3He targets for use in electron scattering experiments. Improvements in the performance of polarized 3He targets, target properties, and operating parameters are documented. Methods: We utilize the technique of alkali-hybrid spin-exchange optical pumping to polarize the 3He targets. Spectrally narrowed diode lasers used for the optical pumping greatly improved the performance. A simulation of the alkali-hybrid spin-exchange optical pumping process was developed to provide guidance in the design of the targets. Data was collected during the characterization of 24 separate glass target cells, each of which was constructed while preparing for one of four experiments at Jefferson Laboratory in Newport News, Virginia. Results: From the data obtained we made determinations of the so-called X -factors that quantify a temperature-dependent and as-yet poorly understood spin-relaxation mechanism that limits the maximum achievable 3He polarization to well under 100%. The presence of the X -factor spin-relaxation mechanism was clearly evident in our data. Good agreement between the simulation and the actual target performance was obtained by including details such as off-resonant optical pumping. Included in our results is a measurement of the K -3He spin-exchange rate coefficient kseK=(7.46 ±0.62 ) ×10-20cm3/s over the temperature range 503 K to 563 K. Conclusions: In order to achieve high performance under the operating conditions described in this paper
17. Tunable femtosecond lasers with low pump thresholds
Science.gov (United States)
Oppo, Karen
The work in this thesis is concerned with the development of tunable, femtosecond laser systems, exhibiting low pump threshold powers. The main motive for this work was the development of a low threshold, self-modelocked Ti:Al2O3 laser in order to replace the conventional large-frame argon-ion pump laser with a more compact and efficient all-solid-state alternative. Results are also presented for an all-solid-state, self-modelocked Cr:LiSAF laser, however most of this work is concerned with self-modelocked Ti:Al2O3 laser systems. In chapter 2, the operation of a regeneratively-initiated, and a hard-aperture self- modelocked Ti:Al2O3 laser, pumped by an argon-ion laser, is discussed. Continuous- wave oscillation thresholds as low as 160mW have been demonstrated, along with self-modelocked threshold powers as low as 500mW. The measurement and suppression of phase noise on modelocked lasers is discussed in chapter 3. This is followed by a comparison of the phase noise characteristics of the regeneratively-initiated, and hard-aperture self-modelocked Ti:Al2O3 lasers. The use of a synchronously-operating, high resolution electron-optical streak camera in the evaluation of timing jitter is also presented. In chapter 4, the construction and self-modelocked operation of an all-solid-state Ti:Al2O3 laser is described. The all-solid-state alternative to the conventional argon-ion pump laser was a continuous-wave, intracavity-frequency doubled, diode-laser pumped Nd:YLF ring laser. At a total diode-laser pump power of 10W, this minilaser was capable of producing a single frequency output of 1W, at 523.5nm in a TEM00 beam. The remainder of this thesis looks at the operation of a self-modelocked Ti:Al2O3 laser generating ultrashort pulses at wavelengths as long as 1053nm. The motive for this work was the development of an all-solid-state, self- modelocked Ti:Al2O3 laser operating at 1053nm, for use as a master oscillator in a Nd:glass power chain.
18. Direct solar-pumped iodine laser amplifier
Science.gov (United States)
Han, Kwang S.; Hwang, In Heon; Kim, Khong Hon; Stock, Larry V.
1988-01-01
A XeCl laser pumped iodine laser oscillator was developed which will be incorporated into the Master Oscillator Power Amplifier (MOPA) system. The developed XeCl laser produces output energy of about 60 mJ per pulse. The pulse duration was about 10 nsec. The kinetic model for the solar-pumped laser was refined and the algorithm for the calculation of a set of rate equations was improved to increase the accuracy and the efficiency of the calculation. The improved algorithm was applied to explain the existing experimental data taken from a flashlamp pumped iodine laser for three kinds of lasants, i-C3F7I, n-C4F9I, and t-C4F9I. Various solid laser materials were evaluated for solar-pumping. The materials studied were Nd:YAG, Nd:YLF, and Cr:Nd:GSGG crystals. The slope efficiency of 0.17 percent was measured for the Nd:YLF near the threshold pump intensity which was 211 solar constants (29W/sq cm). The threshold pump intensity of the Nd:YAG was measured to be 236 solar constants (32W/sq cm) and the near-threshold slope efficiency was 0.12 percent. True CW laser operation of Cr:Nd:GSGG was possible only at pump intensities less than or equal to 1,500 solar constants (203 W/sq cm). This fact was attributed to the high thermal focusing effect of the Cr:Nd:GSGG rod.
19. Laser optically pumped by laser-produced plasma
International Nuclear Information System (INIS)
Silfvast, W.T.; Wood, O.R. II.
1975-01-01
Laser solids, liquids and gases are pumped by a new technique in which the output from an efficient molecular laser, such as a CO 2 laser, ionizes a medium, such as xenon, into a generally cylindrical plasma volume, in proximity to the pumped laser body. Breakdown yields a visible and ultraviolet-radiation-emitting plasma in that volume to pump the laser body. The spectral radiance of the plasma is significantly higher than that produced by a dc-discharge-heated plasma at nearly all wavelengths in the plasma spectrum. The risetime of radiation from the laser-produced plasma can also be significantly shorter than that of a dc heated plasma. A further advantage resides in the fact that in some applications the attenuating walls needed by flashlamps may be eliminated with the result that laser threshold is more readily reached. Traveling wave excitation may be provided by oblique incidence of the pumping laser beam through the ionizable medium to create sequential ionization of portions of that medium along the length of the pumped laser body. (auth)
20. Application of nuclear pumped laser to an optical self-powered neutron detector
Science.gov (United States)
Yamanaka, N.; Takahashi, H.; Iguchi, T.; Nakazawa, M.; Kakuta, T.; Yamagishi, H.; Katagiri, M.
1996-05-01
A Nuclear Pumped Laser (NPL) using 3He/Ne/Ar gas mixture is investigated for a purpose of applying to an optical self-powered neutron detector. Reactor experiments and simulations on lasing mechanism have been made to estimate the best gas pressure and mixture ratios on the threshold input power density (or thermal neutron flux) in 3He/Ne/Ar mixture. Calculational results show that the best mixture pressure is 3He/Ne/Ar=2280/60/100 Torr and thermal neutron flux threshold 5×1012 n/cm2 sec, while the reactor experiments made in the research reactor YAYOI'' of the University of Tokyo and JRR-4'' of JAERI also demonstrate that excitational efficiency is maximized in a similar gas mixture predicted by the calculation.
1. Solar Pumped Lasers and Their Applications
Science.gov (United States)
Lee, Ja H.
1991-01-01
Since 1980, NASA has been pursuing high power solar lasers as part of the space power beaming program. Materials in liquid, solid, and gas phases have been evaluated against the requirements for solar pumping. Two basic characteristics of solar insolation, namely its diffuse irradiance and 5800 K blackbody-like spectrum, impose rather stringent requirements for laser excitation. However, meeting these requirements is not insurmountable as solar thermal energy technology has progressed today, and taking advantage of solar pumping lasers is becoming increasingly attractive. The high density photons of concentrated solar energy have been used for mainly electric power generation and thermal processing of materials by the DOE Solar Thermal Technologies Program. However, the photons can interact with materials through many other direct kinetic paths, and applications of the concentrated photons could be extended to processes requiring photolysis, photosynthesis, and photoexcitation. The use of solar pumped lasers on Earth seems constrained by economics and sociopolitics. Therefore, prospective applications may be limited to those that require use of quantum effects and coherency of the laser in order to generate extremely high value products and services when conventional and inexpensive means are ineffective or impossible. The new applications already proposed for concentrated solar photons, such as destruction of hazardous waste, production of renewable fuel, production of fertilizer, and air/water pollution controls, may benefit from the use of inexpensive solar pumped laser matched with the photochemical kinetics of these processes.
2. Solar pumped continuous wave carbon dioxide laser
Science.gov (United States)
Yesil, O.; Christiansen, W. H.
1978-01-01
In an effort to demonstrate the feasibility of a solar pumped laser concept, gain has been measured in a CO2-He laser medium optically pumped by blackbody radiation. Various gas mixtures of CO2 and He have been pumped by blackbody radiation emitted from an electrically heated oven. Using a CO2 laser as a probe, an optical gain coefficient of 1.8 x 10 to the -3rd/cm has been measured at 10.6 microns for a 9:1 CO2-He mixture at an oven temperature of about 1500 K, a gas temperature of about 400 K and a pressure of about 1 torr. This corresponds to a small signal gain coefficient when allowance is made for saturation effects due to the probe beam, in reasonable agreement with a theoretical value.
3. Diode laser-pumped Ho:YLF laser
International Nuclear Information System (INIS)
Hemmati, H.
1987-01-01
The author reports laser action in Ho:YLF at 2.06 μm following optical pumping with a cw diode laser array. Diode laser-pumped Nd-YAG and Ho:YAG have been reported recently. Lasers with a wavelength of 2 μm have medical and optical communication applications. The diode laser light is focused with a 60-mm focal length lens onto the YLF crystal. A high-reflectivity mirror with 100-mm radius of curvature was used as the output coupler. The lasing threshold was at 5 mWof incident power. This is higher than expected considering that a high reflector was used as the output coupler. However, a more uniform cooling of the crystal is expected to lower the lasing threshold. With 100 mW of pump power coupled into the crystal, --20 mW of 2-μm radiation was observed from this unoptimized setup. The 2-μm laser output is highly sensitive to output coupler alignment, YLF crystal temperature, and pump laser wavelength. The 20% optical conversion efficiency achieved in his preliminary measurements is expected to be improved by better crystal cooling, proper matching of laser wavelength to crystal absorption, variations in the concentration of Ho and sensitizers and use of a proper output coupler. A study of the parameters mentioned above and the effect of crystal temperature on the laser output is under way
4. Threshold pump power of a solar-pumped dye laser
Science.gov (United States)
Lee, Ja H.; Kim, Kyung C.; Kim, Kyong H.
1988-01-01
Threshold solar power for dye laser pumping has been determined by measuring the gain of a rhodamine 6G dye laser amplifier at various solar-simulated irradiances on an amplifier cell. The measured threshold was 20,000 solar constants (2.7 kW/sq cm) for the dye volume of 2 x 5 x 40 cu mm and the optimum dye concentration of 0.001 M. The threshold is about one-third of that achievable with a high-intensity solar concentrator.
5. Development of a 3He nuclear spin flip system on an in-situ SEOP 3He spin filter and demonstration for a neutron reflectometer and magnetic imaging technique
International Nuclear Information System (INIS)
Hayashida, H; Kira, H; Miyata, N; Akutsu, K; Mizusawa, M; Parker, J D; Matsumoto, Y; Oku, T; Sakai, K; Hiroi, K; Shinohara, T; Takeda, M; Yamazaki, D; Oikawa, K; Harada, M; Ino, T; Imagawa, T; Ohkawara, M; Ohoyama, K; Kakurai, K
2016-01-01
We have been developing a 3 He neutron spin filter (NSF) using the spin exchange optical pumping (SEOP) technique. The 3 He NSF provides a high-energy polarized neutron beam with large beam size. Moreover the 3 He NSF can work as a π-flipper for a polarized neutron beam by flipping the 3 He nuclear spin using a nuclear magnetic resonance (NMR) technique. For NMR with the in-situ SEOP technique, the polarization of the laser must be reversed simultaneously because a non-reversed laser reduces the polarization of the spin-flipped 3 He. To change the polarity of the laser, a half-wavelength plate was installed. The rotation angle of the half-wavelength plate was optimized, and a polarization of 97% was obtained for the circularly polarized laser. The 3 He polarization reached 70% and was stable over one week. A demonstration of the 3 He nuclear spin flip system was performed at the polarized neutron reflectometer SHARAKU (BL17) and NOBORU (BL10) at J-PARC. Off-specular measurement from a magnetic Fe/Cr thin film and magnetic imaging of a magnetic steel sheet were performed at BL17 and BL10, respectively. (paper)
6. Scaling studies of solar pumped lasers
Science.gov (United States)
Christiansen, W. H.; Chang, J.
1985-01-01
A progress report of scaling studies of solar pumped lasers is presented. Conversion of blackbody radiation into laser light has been demonstrated in this study. Parametric studies of the variation of laser mixture composition and laser gas temperature were carried out for CO2 and N2O gases. Theoretical analysis and modeling of the system have been performed. Reasonable agreement between predictions in the parameter variation and the experimental results have been obtained. Almost 200 mW of laser output at 10.6 micron was achieved by placing a small sapphire laser tube inside an oven at 1500 K the tube was filled with CO2 laser gas mixture and cooled by longitudinal nitrogen gas flow.
7. Accurate 3He polarimetry using the Rb Zeeman frequency shift due to the Rb-3He spin-exchange collisions
International Nuclear Information System (INIS)
Romalis, M.V.; Cates, G.D.
1998-01-01
We describe a method of 3 He polarimetry relying on the polarization-dependent frequency shift of the Rb Zeeman resonance. Our method is ideally suited for on-line measurements of the 3 He polarization produced by spin-exchange optical pumping. To calibrate the frequency shift we performed an accurate measurement of the imaginary part of the Rb- 3 He spin-exchange cross section in the temperature range typical for spin-exchange optical pumping of 3 He. We also present a detailed study of possible systematic errors in the frequency shift polarimetry. copyright 1998 The American Physical Society
8. Solar pumped laser technology options for space power transmission
Science.gov (United States)
Conway, E. J.
1986-01-01
An overview of long-range options for in-space laser power transmission is presented. The focus is on the new technology and research status of solar-pumped lasers and their solar concentration needs. The laser options include gas photodissociation lasers, optically-pumped solid-state lasers, and blackbody-pumped transfer lasers. The paper concludes with a summary of current research thrusts.
9. E-beam-pumped semiconductor lasers
Science.gov (United States)
Rice, Robert R.; Shanley, James F.; Ruggieri, Neil F.
1995-04-01
The collapse of the Soviet Union opened many areas of laser technology to the West. E-beam- pumped semiconductor lasers (EBSL) were pursued for 25 years in several Soviet Institutes. Thin single crystal screens of II-VI alloys (ZnxCd1-xSe, CdSxSe1-x) were incorporated in laser CRTs to produce scanned visible laser beams at average powers greater than 10 W. Resolutions of 2500 lines were demonstrated. MDA-W is conducting a program for ARPA/ESTO to assess EBSL technology for high brightness, high resolution RGB laser projection application. Transfer of II-VI crystal growth and screen processing technology is underway, and initial results will be reported. Various techniques (cathodoluminescence, one- and two-photon laser pumping, etc.) have been used to assess material quality and screen processing damage. High voltage (75 kV) video electronics were procured in the U.S. to operate test EBSL tubes. Laser performance was documented as a function of screen temperature, beam voltage and current. The beam divergence, spectrum, efficiency and other characteristics of the laser output are being measured. An evaluation of the effect of laser operating conditions upon the degradation rate is being carried out by a design-of-experiments method. An initial assessment of the projected image quality will be performed.
10. Electron-beam pumping of visible and ultraviolet gas lasers
International Nuclear Information System (INIS)
1975-01-01
Several techniques for using direct electron-pumping of gas lasers are reviewed. The primary objective is to categorize pump geometries and to give guidelines for gun selection and pulser design. Examples and application of pump technology are given
11. Heat pump processes induced by laser radiation
Science.gov (United States)
Garbuny, M.; Henningsen, T.
1980-01-01
A carbon dioxide laser system was constructed for the demonstration of heat pump processes induced by laser radiation. The system consisted of a frequency doubling stage, a gas reaction cell with its vacuum and high purity gas supply system, and provisions to measure the temperature changes by pressure, or alternatively, by density changes. The theoretical considerations for the choice of designs and components are dicussed.
12. Excimer Pumped Pulsed Tunable Dye Laser
Science.gov (United States)
Littman, Michael G.
1988-06-01
It has been recently shown and reported for the first time at this meeting, that Excimer pumping of a single-mode, short-cavity, grazing-incidence, longitudinally-pumped pulsed dye laser is feasible. In this paper the key concepts upon which this latest development is based are presented and are in a somewhat unusual form. This manuscript describes five specific dye laser examples. The five examples represent a progression from the simplest type of dye laser to the single-mode version mentioned above. The examples thus serve as a tutorial introduction to potential users of dye lasers. The article is organized into five sections or STEPS, each of which describes a different pulsed dye laser. Since the subtle points about dye lasers are best appreciated only after one actually attempts to build a working model, a PROCEDURES category is included in which details about the construction of the particular form of laser are given. As one reads through this category, think of it as looking over the shoulder of the laser builder. The NOTES category which follows is a brief but essential discussion explaining why various components and procedures are used, as well as how laser performance specifications are obtained. This subsection can he viewed as a discussion with the laser builder concerning the reasons for specific actions and choices made in the assembly of the example laser. The last category contains COMMENTS which provide additional related information pertaining to the example laser that goes beyond the earlier annotated discussion. If you like, these are the narrator's comments. At the end of the article, after the five sequential forms of the laser have been presented, there is a brief summation.
13. Laser-diode pumped Nd:YAG lasers; Laser diode reiki Nd:YAG lasear
Energy Technology Data Exchange (ETDEWEB)
Yuasa, H.; Akiyama, Y.; Nakayama, M. [Toshiba Corp., Tokyo (Japan)
2000-04-01
Laser-diode pumped Nd:YAG lasers are expected to be applied to laser processing fields such as welding, cutting, drilling, and marking due to their potential for high efficiency and compactness. We are designing and developing laser-diode pumped Nd:YAG lasers using numerical analysis simulation techniques such as ray tracing and thermal analysis. We have succeeded in achieving a laser power of more than 3 kW with 20% efficiency, which is the best ever obtained. In addition, we have developed a laser-diode pumped green laser by second harmonic generation, for precision machining on silicon wafers. (author)
14. The 3He Supply Problem
Energy Technology Data Exchange (ETDEWEB)
Kouzes, Richard T.
2009-05-01
One of the main uses for 3He is in gas proportional counters for neutron detection. Radiation portal monitors deployed for homeland security and non-proliferation use such detectors. Other uses of 3He are for research detectors, commercial instruments, well logging detectors, dilution refrigerators, for targets or cooling in nuclear research, and for basic research in condensed matter physics. The US supply of 3He comes almost entirely from the decay of tritium used in nuclear weapons by the US and Russia. A few other countries contribute a small amount to the world’s 3He supply. Due to the large increase in use of 3He for homeland security, the supply has dwindled, and can no longer meet the demand. This white paper reviews the problems of supply, utilization, and alternatives.
15. A new concept for solar pumped lasers
Science.gov (United States)
Christiansen, W. H.
1978-01-01
A new approach is proposed in which an intermediate body heated by sunlight is used as the pumping source for IR systems, i.e., concentration solar radiation is absorbed and reradiated via an intermediate blackbody. This body is heated by focused sunlight to a high temperature and its heat losses are engineered to be small. The cooled laser tube (or tubes) is placed within the cavity and is pumped by it. The advantage is that the radiation spectrum is like a blackbody at the intermediate temperature and the laser medium selectively absorbs this light. Focusing requirements, heat losses, and absorption bandwidths of laser media are examined, along with energy balance and potential efficiency. The results indicate that for lasers pumped through an IR absorption spectrum, the use of an intermediate blackbody offers substantial and important advantages. The loss in radiative intensity for optical pumping by a lower-temperature body is partly compensated by the increased solid angle of exposure to the radiative environment.
16. Theoretical studies of solar pumped lasers
Science.gov (United States)
Harries, Wynford L.
1990-01-01
One concept for collecting solar energy is to use large solar collectors and then use lasers as energy converters whose output beams act as transmission lines to deliver the energy to a destination. The efficiency of the process would be improved if the conversion could be done directly using solar pumped lasers, and the possibility of making such lasers is studied. There are many applications for such lasers, and these are examined. By including the applications first, the requirements for the lasers will be more evident. They are especially applicable to the Space program, and include cases where no other methods of delivering power seem possible. Using the lasers for conveying information and surveillance is also discussed. Many difficulties confront the designer of an efficient system for power conversion. These involve the nature of the solar spectrum, the method of absorbing the energy, the transfer of power into laser beams, and finally, the far field patterns of the beams. The requirements of the lasers are discussed. Specific laser configurations are discussed. The thrust is into gas laser systems, because for space applications, the laser could be large, and also the medium would be uniform and not subject to thermal stresses. Dye and solid lasers are treated briefly. For gas lasers, a chart of the various possibilities is shown, and the various families of gas lasers divided according to the mechanisms of absorbing solar radiation and of lasing. Several specific models are analyzed and evaluated. Overall conclusions for the program are summarized, and the performances of the lasers related to the requirements of various applications.
17. Alkali-vapor laser-excimer pumped alkali laser
International Nuclear Information System (INIS)
Yue Desheng; Li Wenyu; Wang Hongyan; Yang Zining; Xu Xiaojun
2012-01-01
Based on the research internal and overseas, the principle of the excimer pumped alkali laser (XPAL) is explained, and the advantages and disadvantages of the XPAL are analyzed. Taking into consideration the difficulties that the diode pumped alkali laser (DPAL) meets on its development, the ability to solve or avoid these difficulties of XPAL is also analyzed. By summing up the achievements of the XPAL, the possible further prospect is proposed. The XPAL is of possibility to improve the performance of the DPAL. (authors)
18. Feasibility of laser pumping with neutron fluxes from present-day large tokamaks
Energy Technology Data Exchange (ETDEWEB)
Jassby, D.L.
1986-08-01
The minimum fusion-neutron flux needed to observe nuclear-pumped lasing with tokamaks can be reduced substantially by optimizing neutron scattering into the laser cell, located between adjacent toroidal-field coils. The laser lines most readily pumped are probably the /sup 3/He-Ne lines at 0.633 ..mu.. and in the infrared, where the /sup 3/He-Ne gas is excited by energetic ions produced in the /sup 3/He(n,p)T reaction. These lines are expected to lase at the levels of D-T neutron flux foreseen for the TFTR in 1989 (>>10/sup 12/ n/cm/sup 2//s), while amplification should be observable at the existing levels of D-D neutron flux (greater than or equal to 5 x 10/sup 9/ n/cm/sup 2//s). Lasing on the 1.73 ..mu.. and 2.63 ..mu.. transitions of Xe may be observable at the maximum expected levels of D-T neutron flux in TFTR enhanced by scattering.
19. Feasibility of laser pumping with neutron fluxes from present-day large tokamaks
International Nuclear Information System (INIS)
Jassby, D.L.
1986-08-01
The minimum fusion-neutron flux needed to observe nuclear-pumped lasing with tokamaks can be reduced substantially by optimizing neutron scattering into the laser cell, located between adjacent toroidal-field coils. The laser lines most readily pumped are probably the 3 He-Ne lines at 0.633 μ and in the infrared, where the 3 He-Ne gas is excited by energetic ions produced in the 3 He(n,p)T reaction. These lines are expected to lase at the levels of D-T neutron flux foreseen for the TFTR in 1989 (>>10 12 n/cm 2 /s), while amplification should be observable at the existing levels of D-D neutron flux (≥ 5 x 10 9 n/cm 2 /s). Lasing on the 1.73 μ and 2.63 μ transitions of Xe may be observable at the maximum expected levels of D-T neutron flux in TFTR enhanced by scattering
20. Diode pumped solid state laser by two diodes
International Nuclear Information System (INIS)
Li Mingzhong; Zhang Xiaomin; Liang Yue; Man Yongzai; Zhou Pizhang
1995-01-01
A Nd: YLF laser is pumped by home-made quantum well diode lasers. Datum of laser output energy 60 μJ and peak power 120 mw are observed at wavelength 1.047 μm. On the same pumping condition, the output power synchronously pumped by two diodes is higher than the total output power pumped by two diodes separately. The fluctuation is <3%. The results agree with theoretical analysis
1. Semiconductor Laser Diode Pumps for Inertial Fusion Energy Lasers
International Nuclear Information System (INIS)
Deri, R.J.
2011-01-01
Solid-state lasers have been demonstrated as attractive drivers for inertial confinement fusion on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) and at the Omega Facility at the Laboratory for Laser Energetics (LLE) in Rochester, NY. For power plant applications, these lasers must be pumped by semiconductor diode lasers to achieve the required laser system efficiency, repetition rate, and lifetime. Inertial fusion energy (IFE) power plants will require approximately 40-to-80 GW of peak pump power, and must operate efficiently and with high system availability for decades. These considerations lead to requirements on the efficiency, price, and production capacity of the semiconductor pump sources. This document provides a brief summary of these requirements, and how they can be met by a natural evolution of the current semiconductor laser industry. The detailed technical requirements described in this document flow down from a laser ampl9ifier design described elsewhere. In brief, laser amplifiers comprising multiple Nd:glass gain slabs are face-pumped by two planar diode arrays, each delivering 30 to 40 MW of peak power at 872 nm during a ∼ 200 (micro)s quasi-CW (QCW) pulse with a repetition rate in the range of 10 to 20 Hz. The baseline design of the diode array employs a 2D mosaic of submodules to facilitate manufacturing. As a baseline, they envision that each submodule is an array of vertically stacked, 1 cm wide, edge-emitting diode bars, an industry standard form factor. These stacks are mounted on a common backplane providing cooling and current drive. Stacks are conductively cooled to the backplane, to minimize both diode package cost and the number of fluid interconnects for improved reliability. While the baseline assessment in this document is based on edge-emitting devices, the amplifier design does not preclude future use of surface emitting diodes, which may offer appreciable future cost reductions and
2. Efficiency and threshold pump intensity of CW solar-pumped solid-state lasers
Science.gov (United States)
Hwang, In H.; Lee, Ja H.
1991-01-01
The authors consider the relation between the threshold pumping intensity, the material properties, the resonator parameters, and the ultimate slope efficiencies of various solid-state laser materials for solar pumping. They clarify the relation between the threshold pump intensity and the material parameters and the relation between the ultimate slope efficiency and the laser resonator parameters such that a design criterion for the solar-pumped solid-state laser can be established. Among the laser materials evaluated, alexandrite has the highest slope efficiency of about 12.6 percent; however, it does not seem to be practical for a solar-pumped laser application because of its high threshold pump intensity. Cr:Nd:GSGG is the most promising for solar-pumped lasing. Its threshold pump intensity is about 100 air-mass-zero (AM0) solar constants and its slope efficiency is about 12 percent when thermal deformation is completely prevented.
3. Mathematical model of an optically pumped molecular laser
CSIR Research Space (South Africa)
Botha, LR
2009-07-01
Full Text Available A mathematical model was developed that accurately predicts the performance of an optically pumped HBr laser. Relatively high conversion efficiency was achieved. Tm pumped Ho:YLF is a viable source for pumping HBr laser, while HBr can be scaled...
4. Diode lasers optimized in brightness for fiber laser pumping
Science.gov (United States)
Kelemen, M.; Gilly, J.; Friedmann, P.; Hilzensauer, S.; Ogrodowski, L.; Kissel, H.; Biesenbach, J.
2018-02-01
In diode laser applications for fiber laser pumping and fiber-coupled direct diode laser systems high brightness becomes essential in the last years. Fiber coupled modules benefit from continuous improvements of high-power diode lasers on chip level regarding output power, efficiency and beam characteristics resulting in record highbrightness values and increased pump power. To gain high brightness not only output power must be increased, but also near field widths and far field angles have to be below a certain value for higher power levels because brightness is proportional to output power divided by beam quality. While fast axis far fields typically show a current independent behaviour, for broadarea lasers far-fields in the slow axis suffer from a strong current and temperature dependence, limiting the brightness and therefore their use in fibre coupled modules. These limitations can be overcome by carefully optimizing chip temperature, thermal lensing and lateral mode structure by epitaxial and lateral resonator designs and processing. We present our latest results for InGaAs/AlGaAs broad-area single emitters with resonator lengths of 4mm emitting at 976nm and illustrate the improvements in beam quality over the last years. By optimizing the diode laser design a record value of the brightness for broad-area lasers with 4mm resonator length of 126 MW/cm2sr has been demonstrated with a maximum wall-plug efficiency of more than 70%. From these design also pump modules based on 9 mini-bars consisting of 5 emitters each have been realized with 360W pump power.
5. Superfluid 3He dynamcs in 3He - 4He solutions
International Nuclear Information System (INIS)
Mejerovich, A.Eh.
1984-01-01
The dynamics of a 3 He- 4 He superfluid solution with two condensates ( 3 He and 4 He) is investigated. Despite the fact that the hydrodynamics of the system is a three-velocity one (two superfluid and one normal velocity), all the thermo- and hydrodynamic functions are determined by the value of only a single linear combination of the velocities. 0n the basis of an analogy between a moving solution and a BCS system with coupling with a non-zero momentum, the dependence of the thermodynamic quantities on the velocities and critical velocities can easily be calculated for both homogeneous and inhomogeneous phases of the solution. In a magnetic field the temperature oscillations (analogue of second sound for a superfluid solution) are accompanied by oscillations of the magnetic moment. The velocity and damping of the spin-temperature waves are determined. The orienting action of a current on the inhomogeneous phases of the solution is discussed. It is shown that the energy and size of the vortexes in a superfluid solution are, due to drag effects, oscillating functions of the effective mass of the 3 He quasirartictes (pressure). At a pressure of the order of 10 atm a first order transition should take place in the vortex line which is accompanied by an abrupt change of the circulations of superfluid velocity of 3 He for a fixed circulation of the 4 He velocity
6. Advanced solar energy conversion. [solar pumped gas lasers
Science.gov (United States)
Lee, J. H.
1981-01-01
An atomic iodine laser, a candidate for the direct solar pumped lasers, was successfully excited with a 4 kW beam from a xenon arc solar simulator, thus proving the feasibility of the concept. The experimental set up and the laser output as functions of operating conditions are presented. The preliminary results of the iodine laser amplifier pumped with the HCP array to which a Q switch for giant pulse production was coupled are included. Two invention disclosures - a laser driven magnetohydrodynamic generator for conversion of laser energy to electricity and solar pumped gas lasers - are also included.
7. An optimized design of rectangle pumping cell for nuclear reactor pumped laser
International Nuclear Information System (INIS)
Wan, J.-S.; Chen, L.-X.; Zhao, Z.-M.; Pan, X.-B.; Jing, C.-Y.; Zhao, X.-Q.; Liu, F.-H.
2003-01-01
Basing on our research of energy deposition in RPL (Reactor Pumped Laser) pumping cell and the laser power efficiency, a RPL test device on Pulsed Reactor has been designed. In addition, the laser beam power of the RPL test device is estimated in the paper. (author)
8. Flow tube used to cool solar-pumped laser
Science.gov (United States)
1968-01-01
A flow tube has been designed and constructed to provide two major functions in the application of a laser beam for transmission of both sound and video. It maintains the YAG laser at the proper operating temperature of 300 degrees K under solar pumping conditions, and it serves as a pump cavity for the laser crystal.
9. Amplified spontaneous emission in solar-pumped iodine laser
Science.gov (United States)
Cho, Yong S.; Hwang, In H.; Han, Kwang S.; Lee, Ja H.
1992-01-01
The amplified spontaneous emission (ASE) from a long pulse, solar-simulating radiation pumped iodine laser amplifier is studied. The ASE threshold pump intensity is almost proportional to the inverse of the laser gain length when the gas pressure is constant in the laser tube.
10. Reactor operations for nuclear pumping of lasers
Energy Technology Data Exchange (ETDEWEB)
Beck, G; Cooper, G [University of Illinois (United States)
1974-07-01
Experiments involving the measurement of gas parameters that are related to lasing, and lasing of various gas mixtures have comprised a major part of the utilization of the University of Illinois Advanced TRIGA Reactor since the upgrading of the facility was completed in 1969. A thru beam port, which was added during upgrading, has been the facility used for these measurements. The laser cell is placed in the port adjacent to the core. Alignment is then accomplished by using both ends of the port or by a mirror placed at the back side of the apparatus. The reactor has been operated in all modes (pulsing, square wave, and steady state) for the experiments although pulsing is the primary mode that is used. Laser enhancement has been obtained in several cases, but efforts toward direct pumping from the radiation alone have not as yet succeeded. Improved laser operation from direct pumping has been suggested with an emphasis on high-powered systems where the basic input energy is to be derived from a nuclear reactor.
11. Solar-pumped gas laser development
Science.gov (United States)
Wilson, J. W.
1981-01-01
The direct conversion of solar radiation into an inverted population for extraction in an optical cavity holds promise as a relatively simple system design. Broad-band photoabsorption in the visible or near-UV range is required to excite large volumes of gas and to ensure good solar absorption efficiency. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than approximately 10 A. The system should show chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. A search of electronic-vibrational transitions in diatomic molecules satisfying these conditions is now in progress. A photodissociation-pumped atomic iodine laser is now being tested under solar pumping conditions. Photodissociation studies for thallium spin-flip metastable formation will begin in the near future.
12. Laser optical pumping of sodium and lithium atom beams
International Nuclear Information System (INIS)
Cusma, J.T.
1983-01-01
The method of optical pumping with a continuous wave dye laser has been used to produce beams of polarized 23 Na atoms and polarized 6 Li atoms. Optical pumping of a 23 Na atom beam using either a multimode dye laser or a single frequency dye laser with a double passed acousto-optic modulator results in electron spin polarizations of 0.70-0.90 and nuclear spin polarizations of 0.75-0.90. Optical pumping of a 6 Li atom beam using a single frequency dye laser either with an acousto-optic modulator or with Doppler shift pumping results in electron spin polarizations of 0.77-0.95 and nuclear spin polarizations greater than 0.90. The polarization of the atom beam is measured using either the laser induced fluorescence in an intermediate magnetic field or a 6-pole magnet to determine the occupation probabilities of the ground hyperfine sublevels following optical pumping. The results of the laser optical pumping experiments agree with the results of a rate equation analysis of the optical pumping process which predicts that nearly all atoms are transferred into a single sublevel for our values of laser intensity and interaction time. The use of laser optical pumping in a polarized ion source for nuclear scattering experiments is discussed. The laser optical pumping method provides a means of constructing an intense source of polarized Li and Na ions
International Nuclear Information System (INIS)
Duband, L.; Ravex, A.; Lange, A.
1991-01-01
A self-contained, recyclable laboratory 3 He refrigerator has been developed. The refrigerator is very compact, portable and is designed to be safe and reliable. The unit can easily be installed on the cold plate of a superfluid 4 He cryostat. Once bolted on the cold plate, operation of the refrigerator is controlled by a single heater. In this new design the refrigerator has a cylindrical geometry. The adsorption pump is placed above the condensation point to prevent convection during the condensation phase and to improve the pumping speed. The inhibition of convection reduces the load on the 4 He bath and increases the condensation efficiency. This refrigeration technique has great potential for space applications. The absence of moving parts makes the system reliable and vibration free. Its simplicity and the absence of external components facilitate its integration on a cryostat. In fact, a rocket-borne 3 He refrigerator has already been successfully flown and has demonstrated the feasibility of this method
14. Lagrangian of superfluid 3He
International Nuclear Information System (INIS)
Theodorakis, S.
1988-01-01
This paper presents a phenomenological Lagrangian that fully describes the dynamics of any homogeneous phase of superfluid 3 He, unitary or not, omitting relaxation. This Lagrangian is built by using the concept of a local SO(3) x SO(3) x U(1) symmetry. The spin and angular momentum play the role of gauge fields. We derive the Leggett equations for spin and orbital dynamics from the equations of motion, for both the A and the B phase. This Lagrangian not only enables us to describe both the spin and orbital dynamics of superfluid 3 He in a unified fashion, but can also be used for finding the dynamics in any experimental situation. Furthermore, it can describe the dynamics of the magnitude, as well as of the orientation of the order parameter, and thus it can be used to describe the dynamics of the A-B phase transition
15. Development of short pulse laser pumped x-ray lasers
International Nuclear Information System (INIS)
Dunn, J; Osterheld, A L; Hunter, J R; Shlyaptsev, V N
2000-01-01
X-ray lasers have been extensively studied around the world since the first laboratory demonstration on the Novette laser at LLNL in 1984 [l]. The characteristic properties of short wavelength, high monochromaticity, collimation and coherence make x-ray lasers useful for various applications. These include demonstrations of biological imaging within the water window, interferometry of laser plasmas and radiography of laser-heated surfaces. One of the critical issues has been the high power pump required to produce the inversion. The power scaling as a function of x-ray laser wavelength follows a -k4 to law. The shortest x-ray laser wavelength of ∼ 35 (angstrom) demonstrated for Ni-like All was at the limit of Nova laser capabilities. By requiring large, high power lasers such as Nova, the shot rate and total number of shots available have limited the rapid development of x-ray lasers and applications. In fact over the last fifteen years the main thrust has been to develop more efficient, higher repetition rate x-ray lasers that can be readily scaled to shorter wavelengths. The recent state of progress in the field can be found in references. The objective of the project was to develop a soft x-ray laser (XRL) pumped by a short pulse laser of a few joules. In effect to demonstrate a robust, worlung tabletop x-ray laser at LLNL for the first time. The transient collisional scheme as proposed by Shlyaptsev et al [8, 9] was the candidate x-ray laser for study. The successful endeavour of any scientific investigation is often based upon prudent early decisions and the choice of this scheme was both sound and fruitful. It had been demonstrated very recently for Ne-like Ti at 326 A using a small tabletop laser [10] but had not yet reached its full potential. We chose this scheme for several reasons: (a) it was a collisional-type x-ray laser which has been historically the most robust; (b) it had the promise of high efficiency and low energy threshold for lasing; (c) the
16. New photoionization lasers pumped by laser-induced plasma radiation
International Nuclear Information System (INIS)
Hube, M.; Dieckmann, M.; Beigang, R.; Welling, H.; Wellegehausen, B.
1988-01-01
Innershell photoionization of atomic gases and vapors by soft x rays from a laser-produced plasma is a potential method for making lasers at short wavelengths. Normally, in such experiments only a single plasma spot or plasma line is created for the excitation. This gives high excitation rates but only a short excitation length. At high excitation rates detrimental influences, such as amplified spontaneous emission, optical saturation, or quenching processes, may decrease or even destroy a possible inversion. Therefore, it seems to be more favorable to use a number of separated plasma spots with smaller excitation rates and larger excitation lengths. As a test, a three-plasma spot device was constructed and used in the well-known Cd-photoionization laser at 442 nm. With a 600-mJ Nd:YAH laser (pulse length, 8 ns) for plasma production, output energies up to 300 μJ have been measured, which is more than a doubling of so far obtained data. On innershell excitation, levels may be populated that allow direct lasers as in the case of Cd or that are metastable and cannot be directly coupled to lower levels. In this case modifications in the excitation process are necessary. Such modifications may be an optical pump process in the atom prior to the innershell photoionization or an optical pump process (population transfer process) after the innershell ionization, leading to Raman or anti-Stokes Raman-type laser emissions. With these techniques and the developed multiplasma spot excitation device a variety of new laser emissions in K and Cs ions have been achieved which are indicated in the level schemes
17. Development of frequency tunable Ti:sapphire laser and dye laser pumped by a pulsed Nd:YAG laser
International Nuclear Information System (INIS)
Yi, Jong Hoon; Horn, Roland; Wendt, K.
2001-01-01
We investigated lasing characteristics of two kinds of tunable laser, liquid dye laser and solid Ti:sapphire crystal laser, pumped by high pulse repetition rate Nd:YAG laser. Dye laser showed drastically reduced pulsewidth compared with that of pump laser and it also contained large amount of amplified spontaneous emission. Ti:sapphire laser showed also reduced pulsewidth. But, the laser conversion pump laser and Ti:sapphire laser pulse, we used a Brewster-cut Pockel's cell for Q-switching. The laser was frequency doubled by a type I BBO crystal outside of the cavity.
18. Nonimaging concentrators for diode-pumped slab lasers
Science.gov (United States)
Lacovara, Philip; Gleckman, Philip L.; Holman, Robert L.; Winston, Roland
1991-10-01
Diode-pumped slab lasers require concentrators for high-average power operation. We detail the properties of diode lasers and slab lasers which set the concentration requirements and the concentrator design methodologies that are used, and describe some concentrator designs used in high-average power slab lasers at Lincoln Laboratory.
19. Key techniques for space-based solar pumped semiconductor lasers
Science.gov (United States)
He, Yang; Xiong, Sheng-jun; Liu, Xiao-long; Han, Wei-hua
2014-12-01
In space, the absence of atmospheric turbulence, absorption, dispersion and aerosol factors on laser transmission. Therefore, space-based laser has important values in satellite communication, satellite attitude controlling, space debris clearing, and long distance energy transmission, etc. On the other hand, solar energy is a kind of clean and renewable resources, the average intensity of solar irradiation on the earth is 1353W/m2, and it is even higher in space. Therefore, the space-based solar pumped lasers has attracted much research in recent years, most research focuses on solar pumped solid state lasers and solar pumped fiber lasers. The two lasing principle is based on stimulated emission of the rare earth ions such as Nd, Yb, Cr. The rare earth ions absorb light only in narrow bands. This leads to inefficient absorption of the broad-band solar spectrum, and increases the system heating load, which make the system solar to laser power conversion efficiency very low. As a solar pumped semiconductor lasers could absorb all photons with energy greater than the bandgap. Thus, solar pumped semiconductor lasers could have considerably higher efficiencies than other solar pumped lasers. Besides, solar pumped semiconductor lasers has smaller volume chip, simpler structure and better heat dissipation, it can be mounted on a small satellite platform, can compose satellite array, which can greatly improve the output power of the system, and have flexible character. This paper summarizes the research progress of space-based solar pumped semiconductor lasers, analyses of the key technologies based on several application areas, including the processing of semiconductor chip, the design of small and efficient solar condenser, and the cooling system of lasers, etc. We conclude that the solar pumped vertical cavity surface-emitting semiconductor lasers will have a wide application prospects in the space.
20. Fine and hyperfine structure spectra of the ultra-violet 23S → 53P transition in 4He and 3He with a frequency doubled CW ring laser, detected via associative ionization
International Nuclear Information System (INIS)
Runge, S.; Pesnelle, A.; Perdrix, M.; Sevin, D.; Wolffer, N.; Watel, G.
1982-01-01
High resolution laser spectroscopy coupled to a sensitive method of detection via mass analysis of He + 2 ions produced in He(5 3 P) + He(1 1 S) collisions, is used to obtain the fine and hyperfine spectra of the ultra-violet He 2 3 S → 5 3 P transition. A cw tunable UV radiation around 294.5 nm is generated by intracavity frequency doubling a Rhodamine 6G single mode ring dye laser using an ADA crystal. Both spectra enable fine and hyperfine structures to be determined within a few MHz. The magnetic dipole coupling constant A of the 5 3 P term of 3 He is found to be -4326 +- 9 MHz (-0.1443 +- 0.0003 cm -1 ). (orig.)
1. Solar-pumped lasers for space power transmission
Science.gov (United States)
Taussig, R.; Bruzzone, C.; Nelson, L.; Quimby, D.; Christiansen, W.
1979-01-01
Multi-Megawatt CW solar-pumped lasers appear to be technologically feasible for space power transmission in the 1990s time frame. A new concept for a solar-pumped laser is presented which utilizes an intermediate black body cavity to provide a uniform optical pumping environment for the lasant, either CO or CO2. Reradiation losses are minimized with resulting high efficiency operation. A 1 MW output laser may weigh as little as 8000 kg including solar collector, black body cavity, laser cavity and ducts, pumps, power systems and waste heat radiator. The efficiency of such a system will be on the order of 10 to 20%. Details of the new concept, laser design, comparison to competing solar-powered lasers and applications to a laser solar power satellite (SPS) concept are presented.
2. Development of diode-pumped medical solid-state lasers
International Nuclear Information System (INIS)
Kim, Cheol Jung; Kim, Min Suk
2000-09-01
Two thirds of human body consists of water and the absorption of laser by water is an important factor in medical laser treatment. Er medical lasers have been used in the dermatology, ophthalmology and dental treatments due to its highest absorption by water. However, 2.9 um Er laser can not be transmitted through an optical fiber. On the other hand, Tm laser can be transmitted through an fiber and also has very high absorption by water. Therefore, Tm lasers are used in ophthalmology and heart treatment wherein the fiber delivery is very important for the treatment. Until now, mainly lamp-pumped solid-state lasers have been used in medical treatments, but the lamp-pumped solid-state lasers are being replaced with the diode-pumped solid-state lasers because the diode-pumped solid-state lasers are more compact and much easier to maintain. Following this trend, end-pumped Er and side-pumped Tm lasers have been developed and the output power of 1 W was obtained for Er and Tm respectively
3. Development of diode-pumped medical solid-state lasers
Energy Technology Data Exchange (ETDEWEB)
Kim, Cheol Jung; Kim, Min Suk
2000-09-01
Two thirds of human body consists of water and the absorption of laser by water is an important factor in medical laser treatment. Er medical lasers have been used in the dermatology, ophthalmology and dental treatments due to its highest absorption by water. However, 2.9 um Er laser can not be transmitted through an optical fiber. On the other hand, Tm laser can be transmitted through an fiber and also has very high absorption by water. Therefore, Tm lasers are used in ophthalmology and heart treatment wherein the fiber delivery is very important for the treatment. Until now, mainly lamp-pumped solid-state lasers have been used in medical treatments, but the lamp-pumped solid-state lasers are being replaced with the diode-pumped solid-state lasers because the diode-pumped solid-state lasers are more compact and much easier to maintain. Following this trend, end-pumped Er and side-pumped Tm lasers have been developed and the output power of 1 W was obtained for Er and Tm respectively.
4. Self-sustaining nuclear pumped laser-fusion reactor experiment
International Nuclear Information System (INIS)
Boody, F.P.; Choi, C.K.; Miley, G.H.
1977-01-01
The features of a neutron feedback nuclear pumped (NFNP) laser-fusion reactor equipment were studied with the intention of establishing the feasibility of the concept. The NFNP laser-fusion concept is compared schematically to electrically pumped laser fusion. The study showed that, once a method of energy storage has been demonstrated, a self-sustaining fusion-fission hybrid reactor with a ''blanket multiplication'' of two would be feasible using nuclear pumped Xe F* excimer lasers having efficiencies of 1 to 2 percent and D-D-T pellets with gains of 50 to 100
5. High brightness diode-pumped organic solid-state laser
Energy Technology Data Exchange (ETDEWEB)
Zhao, Zhuang; Mhibik, Oussama; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien, E-mail: [email protected] [Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430, Villetaneuse (France); CNRS, UMR 7538, LPL, F-93430, Villetaneuse (France)
2015-02-02
High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.
6. Development of a {sup 3}He magnetometer for a neutron electric dipole moment experiment
Energy Technology Data Exchange (ETDEWEB)
Kraft, Andreas; Heil, Werner; Lauer, Thorsten; Neumann, Daniel [Johannes Gutenberg University, Institute of Physics, Mainz (Germany); Koch, Hans-Christian [Johannes Gutenberg University, Institute of Physics, Mainz (Germany); University of Fribourg, Physics Department, Fribourg (Switzerland); Daum, Manfred [Paul Scherrer Institute, Villigen (Switzerland); Pazgalev, Anatoly [Ioffe Institute, St Petersburg (Russian Federation); Sobolev, Yuri [Johannes Gutenberg University, Institute of Nuclear Chemistry, Mainz (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Weis, Antoine [University of Fribourg, Physics Department, Fribourg (Switzerland)
2014-01-01
We have developed a highly sensitive {sup 3}He magnetometer for the accurate measurement of the magnetic field in an experiment searching for an electric dipole moment of the neutron. By measuring the Larmor frequency of nuclear spin polarized {sup 3}He atoms a sensitivity on the femto-Tesla scale can be achieved. A {sup 3}He/Cs-test facility was established at the Institute of Physics of the Johannes Gutenberg University in Mainz to investigate the readout of {sup 3}He free induction decay with a lamp-pumped Cs magnetometer. For this we designed and built an ultra-compact and transportable polarizer unit which polarizes {sup 3}He gas up to 55% by metastability exchange optical pumping. The polarized {sup 3}He was successfully transfered from the polarizer into a glass cell mounted in a magnetic shield and the {sup 3}He free induction decay was detected by a lamp-pumped Cs magnetometer. (orig.)
7. Optically pumped FIR lasers and their application in plasma diagnostics
International Nuclear Information System (INIS)
Bakos, J.S.
1986-06-01
The pysics and the construction of the far infrared lasers (FIRL) and of the infrared lasers pumping them are reviewed. The details of the construction, resonating and pumping systems, spectral and power characteristics of the FIRLs are discussed. Recently more than 1000 laser lines are known and used in the 27-80 mm wavelength range, but in many cases the laser kinetics are not fully understood, and some instability phenomena cannot be prevented. New nonlinear processes were found: two-photon pumping, hyper Raman laser tuning and relaxation phenomena. A broad application field, the plasma diagnostics by far infrared lasers is described. Scattering of infrared laser radiation can give new interesting information on the not understood effect of the anomalous transport in the high temperature plasma. (D.Gy.)
8. Detailed Balance Limit of Efficiency of Broadband-Pumped Lasers.
Science.gov (United States)
Nechayev, Sergey; Rotschild, Carmel
2017-09-13
Broadband light sources are a wide class of pumping schemes for lasers including LEDs, sunlight and flash lamps. Recently, efficient coupling of broadband light to high-quality micro-cavities has been demonstrated for on-chip applications and low-threshold solar-pumped lasers via cascade energy transfer. However, the conversion of incoherent to coherent light comes with an inherent price of reduced efficiency, which has yet to be assessed. In this paper, we derive the detailed balance limit of efficiency of broadband-pumped lasers and discuss how it is affected by the need to maintain a threshold population inversion and thermodynamically dictated minimal Stokes' shift. We show that lasers' slope efficiency is analogous to the nominal efficiency of solar cells, limited by thermalisation losses and additional unavoidable Stokes' shift. The lasers' power efficiency is analogous to the detailed balance limit of efficiency of solar cells, affected by the cavity mirrors and impedance matching factor, respectively. As an example we analyze the specific case of solar-pumped sensitized Nd 3+ :YAG-like lasers and define the conditions to reach their thermodynamic limit of efficiency. Our work establishes an upper theoretical limit for the efficiency of broadband-pumped lasers. Our general, yet flexible model also provides a way to incorporate other optical and thermodynamic losses and, hence, to estimate the efficiency of non-ideal broadband-pumped lasers.
9. Direct solar pumping of semiconductor lasers: A feasibility study
Science.gov (United States)
Anderson, Neal G.
1992-01-01
This report describes results of NASA Grant NAG-1-1148, entitled Direct Solar Pumping of Semiconductor Lasers: A Feasibility Study. The goals of this study were to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space with directly focused sunlight and to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or storage battery electrically pumping a current injection laser. With external modulation, such lasers could perhaps be efficient sources for intersatellite communications. We proposed specifically to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation at low pump intensities. These tasks have been accomplished, as described in this report of our completed project. The report is organized as follows: Some general considerations relevant to the solar-pumped semiconductor laser problem are discussed in Section 2, and the types of structures chosen for specific investigation are described. The details of the laser model we developed for this work are then outlined in Section 3. In Section 4, results of our study are presented, including designs for optimum lattice-matched and strained-layer solar-pumped quantum-well lasers and threshold pumping estimates for these structures. It was hoped at the outset of this work that structures could be identified which could be expected to operate continuously at solar photoexcitation intensities of several thousand suns, and this indeed turned out to be the case as described in this section. Our project is
10. Frequency-doubled diode laser for direct pumping of Ti:sapphire lasers
DEFF Research Database (Denmark)
Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika
2012-01-01
. However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20...... fs are measured. These results open the opportunity of establishing diode laser pumped Ti:sapphire lasers for e.g. biophotonic applications like retinal optical coherence tomography or pumping of photonic crystal fibers for CARS microscopy.......A single-pass frequency doubled high-power tapered diode laser emitting nearly 1.3 W of green light suitable for direct pumping of Ti:sapphire lasers generating ultrashort pulses is demonstrated. The pump efficiencies reached 75 % of the values achieved with a commercial solid-state pump laser...
11. Efficient Ho:YLF laser pumped by a Tm:fiber laser
CSIR Research Space (South Africa)
Koen, W
2013-10-01
Full Text Available A thulium fiber laser pumped Ho:YLF laser delivering 45.1 W in a near diffraction limited beam when pumped with 84.7 W is demonstrated. The optical-to-optical efficiency of 53 % compares favorably with similar Ho:YAG lasers....
12. Solar pumped laser and its application to hydrogen production
International Nuclear Information System (INIS)
Imasaki, K.; Saiki, T.; Li, D.; Motokosi, S.; Nakatsuka, M.
2007-01-01
Solar pumped laser has been studied. Recently, a small ceramic laser pumped by pseudo solar light shows high efficiency of more than 40% which exceeds a solar cell. Such solar pumped laser can concentrate the large area of solar energy in a focused spot of small area. This fact implies the application of such laser for clean and future renewable energy source as hydrogen. For this purpose, 100 W level laboratory solar laser HELIOS is completed using disk ceramic active mirror laser to achieve high temperature. This laser is a kind of MOPA system. Oscillator of additional small laser is used. Laser light is generated in oscillator and is amplified in ceramic disks of solar pumped. The temperature from this system is to be more than 1500 K. We will use a simple graphite cavity for laser power absorption and to get a high temperature. We are also designing a 10 MW CW laser based on this technology. This may be expected an application of solar energy for hydrogen production with total efficiency of 30%
13. Theoretical studies of solar-pumped lasers
Science.gov (United States)
Harries, W. L.
1983-01-01
Possible types of lasers were surveyed for solar power conversion. The types considered were (1) liquid dye lasers, (2) vapor dye lasers, and (3) nondissociative molecular lasers. These are discussed.
14. Overview and future direction for blackbody solar-pumped lasers
Science.gov (United States)
Deyoung, R. J.
1988-01-01
A review of solar-pumped blackbody lasers is given which addresses their present status and suggests future research directions. The blackbody laser concept is one system proposed to scale to multimegawatt power levels for space-to-space power transmissions for such applications as onboard spacecraft electrical or propulsion needs. Among the critical technical issues are the scalability to high powers and the laser wavelength which impacts the transmission optics size as well as the laser-to-electric converter at the receiver. Because present blackbody solar-pumped lasers will have laser wavelengths longer than 4 microns, simple photovoltaic converters cannot be used, and transmission optics will be large. Thus, future blackbody laser systems should emphasize near visible laser wavelengths.
15. Application of the three-body model to the reactions 6Li(3He,t 3He)3He and 6Li(3He,3He3He)3H
International Nuclear Information System (INIS)
Haftel, M.I.; Allas, R.G.; Beach, L.A.; Bondelid, R.O.; Petersen, E.L.; Slaus, I.; Lambert, J.M.; Treado, P.A.
1977-01-01
Experimental and theoretical cross sections are presented for the 6 Li( 3 He, 3 He 3 He) 3 H and 6 Li( 3 He,t 3 He) 3 He reactions for the symmetric angle pairs 20 0 -20 0 , 28.3 0 -28.3 0 , and 35 0 -35 0 . The theoretical cross sections are calculated in a three-body model where the trions (i.e., mass-3 nuclei) are treated as elementary particles with 6 Li being a 3 He- 3 H bound state. The trion-trion interaction is represented by S wave separable potentials with the breakup cross sections calculated with the tree-body Haftel-Ebenhoeh code. the Coulomb interaction is taken into account by fitting the separable potential parameters to the trion-trion scattering data and is included approximately in the breakup code. The experimental cross sections are compared with both the plane-wave impulse approximation and the three-body model predictions. The plane-wave impulse approximation predicts both the shapes and magnitudes poorly (10 to 20 times experiment). Without Coulomb corrections the three-body model gives good agreement with experiment for the shapes of the spectra with the magnitudes generally being about 40% of experiment for 6 Li( 3 He, 3 He 3 He) 3 H and about 80% for 6 Li( 3 He,t 3 He) 3 He. The Coulomb corrections improve the magnitudes predicted by the three-body model but not the shapes. It is observed that for these reactions S wave separable potentials describe the breakup data much better than they do the two-body trion-trion scattering data. This result should encourage further three-body treatment of these and similar reactions
16. A solar simulator-pumped atomic iodine laser
Science.gov (United States)
Lee, J. H.; Weaver, W. R.
1981-01-01
An atomic iodine laser, a candidate for the direct solar-pumped gas laser, was excited with a 4-kW beam from a xenon arc solar simulator. Continuous lasing at 1.315 micron for over 10 ms was obtained for static filling of n-C3F7I vapor. By momentarily flowing the lasant, a 30-Hz pulsed output was obtained for about 200 ms. The peak laser power observed was 4 W for which the system efficiency reached 0.1%. These results indicate that direct solar pumping of a gas laser for power conversion in space is indeed feasible.
17. Repetitive 1 Hz fast-heating fusion driver HAMA pumped by diode pumped solid state laser
International Nuclear Information System (INIS)
Mori, Yoshitaka; Sekine, Takashi; Komeda, Osamu
2014-01-01
We describe a repetitive fast-heating fusion driver called HAMA pumped by Diode Pumped Solid State Laser (DPSSL) to realize the counter irradiation of sequential implosion and heating laser beams. HAMA was designed to activate DPSSL for inertial confinement fusion (ICF) research and to realize a unified ICF machine for power plants. The details of a four-beam alignment scheme and the results of the counter irradiation of stainless plates are shown. (author)
18. Analysis of the pump-beam path in corner-pumped slab laser
International Nuclear Information System (INIS)
Chen Li; Qiang Liu; Mali Gong; Gang Chen; Ping Yan
2007-01-01
The propagation of the pump radiation in active slab elements is considered. Conditions of the total internal reflection of the pump radiation are obtained, and are used to construct a series of graphical illustrations of reflection characteristics of different active elements. (control of laser radiation parameters)
19. Quantum mechanical features of optically pumped CW FIR lasers
Science.gov (United States)
Seligson, D.; Leite, J. R. R.; Sanchez, A.; Feld, M. S.; Ducloy, M.
1977-01-01
Quantum mechanical predictions for the gain of an optically pumped CW FIR laser are presented for cases in which one or both of the pump and FIR transitions are pressure or Doppler broadened. The results are compared to those based on the rate equation model. Some of the quantum mechanical predictions are verified in CH3OH.
20. Pump polarization insensitive and efficient laser-diode pumped Yb:KYW ultrafast oscillator.
Science.gov (United States)
Wang, Sha; Wang, Yan-Biao; Feng, Guo-Ying; Zhou, Shou-Huan
2016-02-01
We theoretically and experimentally report and evaluate a novel split laser-diode (LD) double-end pumped Yb:KYW ultrafast oscillator aimed at improving the performance of an ultrafast laser. Compared to a conventional unpolarized single-LD end-pumped ultrafast laser system, we improve the laser performance such as absorption efficiency, slope efficiency, cw mode-locking threshold, and output power by this new structure LD-pumped Yb:KYW ultrafast laser. Experiments were carried out with a 1 W output fiber-coupled LD. Experimental results show that the absorption increases from 38.7% to 48.4%, laser slope efficiency increases from 18.3% to 24.2%, cw mode-locking threshold decreases 12.7% from 630 to 550 mW in cw mode-locking threshold, and maximum output-power increases 28.5% from 158.4 to 221.5 mW when we switch the pump scheme from an unpolarized single-end pumping structure to a split LD double-end pumping structure.
1. Dimerization of 3He in 3He-4He mixture films
International Nuclear Information System (INIS)
Bashkin, E.
1994-01-01
3 He atoms dissolved in superfluid 4 He may form dimers ( 3 He) 2 in two-dimensional geometries. Dimer formation is studied in films of dilute 3 He- 4 He mixture. After designing a schematic 3 He- 3 He interaction potential, the dimer binding energy is calculated for various substrates. It is shown that 3 He impurity states localized near the substrate give rise to the highest magnitudes of the binding energy. (author). 32 refs., 6 figs.,; 1 tab
2. Novel laterally pumped by prism laser configuration for compact solid-state lasers
International Nuclear Information System (INIS)
Dascalu, T; Salamu, G; Sandu, O; Voicu, F; Pavel, N
2013-01-01
We propose a new laser configuration in which the pump radiation is coupled into the laser crystal through a prism. The laser medium is square shaped and the prism is attached on one of its lateral sides, near one of the crystal extremities. The diode-laser fiber end is placed close to the prism hypotenuse, the pump radiation is coupled into the laser crystal through the opposite surface of the prism and propagates into the crystal through total internal reflections. This laser geometry is simple to align and permits the realization of compact diode-pumped laser systems, as well as power scaling. A diode-pumped Nd:YAG laser yielding pulses of 2.1 mJ energy under a pump with pulses of 9.9 mJ is demonstrated. The laser slope efficiency is 0.22. Furthermore, this geometry enables one to obtain passively Q-switched lasers with the saturable absorber crystal placed between the resonator high-reflectivity mirror and the laser crystal. A Nd:YAG laser, passively Q-switched by a Cr 4+ :YAG crystal with initial transmission T 0 = 0.90, delivering laser output with a pulsed energy of 93 μJ, a duration of 26 ns and a pump threshold of 1.9 mJ, is realized in order to prove the concept. (letter)
3. Seven-laser diode end-pumped Nd
International Nuclear Information System (INIS)
Berger, J.; Welch, D.F.; Streifer, W.; Scifres, D.R.; Smith, J.J.; Hoffman, H.J.; Peisley, D.; Radecki, D.
1988-01-01
End pumping of solid-state lasers by single semiconductor laser diode arrays (LDAs) is efficient, but the maximum pump power is limited by the source brightness and matching the TEM/sub 00/ Nd:YAG cavity mode. To increase the output power from a solid-state Nd:YAG laser, one option is to employ a multiplicity of LDA to provide more pump power than is available from a single source. The authors report herein a 660-mW cw TEM/sub 00/ Nd:YAG laser, end-pumped by seven LDA, with bundled optical fibers coupling the light from each diode to the Nd:YAG rod end. The maximum electrical-to-optical conversion efficiency attained was 4.7% at 560-mW Nd:YAG output power. The LDAs (SDL-2430-C, 100 μm wide) were mounted on separate thermoelectric coolers to tune emission wavelength to the Nd:YAG absorption bands. The diodes were operated at their rated output power (50,000 h mean time to failure). The 110/125-μm diam 0.37-N.A. fibers were butt coupled to the lasers and glued together into a hexagonal close pack. The authors have obtained the highest average power demonstrated to date in the TEM/sub 00/ mode from a Nd:YAG laser, reliably end-pumped by multiple laser diodes with good efficiency
4. A dye center laser pumped by emission from copper vapor and dye lasers
Energy Technology Data Exchange (ETDEWEB)
Loktyushin, A A; Chernyshev, A I; Soldatov, A N; Sukhanov, V B; Troitskiy, V O
1983-01-01
LiF:F2+ lasing is reported for the case of pumping by total emission with frequencies of 570.6 and 578.2 nanometers or by a single yellow copper vapor laser line and emission from an oxazene-17 dye laser excited by emission from a Cu laser. Lasing with a mean power level of 23 milliwatts with a maximum at 911 nanometers is obtained. The maximum efficiency was 3.4 percent with pumping of the dye centers by emission from the yellow Cu laser line. The lasing characteristics of the laser for all the types of pumping used are given.
5. An application of the theory of laser to nitrogen laser pumped dye laser
International Nuclear Information System (INIS)
Osman, Fatima Ahmed
1998-03-01
In this thesis we gave a general discussion on lasers, reviewing some of their properties, types and application. We also conducted an experiment where we obtained a dye laser pumped by nitrogen laser with a wave length of 337.1 nm and a power of 5 Mw.It was noticed that the produced radiation possesses characteristics different from those of other types of laser. This characteristics determine the tunability i.e the possibility of choosing the appropriately required wave-length of radiation for various applications.(Author)
6. Capacitive-discharge-pumped copper bromide vapour laser
International Nuclear Information System (INIS)
Sukhanov, V B; Fedorov, V F; Troitskii, V O; Gubarev, F A; Evtushenko, Gennadii S
2007-01-01
A copper bromide vapour laser pumped by a high-frequency capacitive discharge is developed. It is shown that, by using of a capacitive discharge, it is possible to built a sealed off metal halide vapour laser of a simple design allowing the addition of active impurities into the working medium. (letters)
7. Pulsed CH3OH terahertz laser radiation pumped by 9P(36) CO2 lasers
International Nuclear Information System (INIS)
Jiu Zhixian; Zuo Duluo; Miao Liang; Cheng Zuhai
2011-01-01
An efficient pulsed CH 3 OH terahertz (THz) laser pumped by a TEA CO 2 laser was investigated experimentally. A simple terahertz cavity and a TEA CO 2 laser for the optically pumped THz radiation were studied experimentally. To improve THz laser energy and photon conversion efficiency, two different TEA CO 2 lasers were developed to pump CH 3 OH. When CH 3 OH was pumped by the 9P(36) line with different powers of the CO 2 laser, the generation of terahertz radiation with energy as high as 0.307mJ and 23.75mJ were obtained, respectively. The corresponding photon conversion efficiencies were 0.29% and 2.4%. The photon conversion efficiency increases by a factor of about 8. Meanwhile, higher peak power of pump laser effectively improves the photon conversion efficiency. And the optimum THz laser pressure increases with narrower pulse width of pump laser because of increasing absorptive gases molecules of CH 3 OH with higher peak power of pump laser.
8. Diode-pumped solid state laser for inertial fusion energy
International Nuclear Information System (INIS)
Payne, S.A.; Krupke, W.F.; Orth, C.D.
1994-11-01
The authors evaluate the prospect for development of a diode-pumped solid-state-laser driver in an inertial fusion energy power plant. Using a computer code, they predict that their 1 GWe design will offer electricity at 8.6 cents/kW · hr with the laser operating at 8.6% efficiency and the recycled power level at 31%. The results of their initial subscale experimental testbed of a diode-pumped solid state laser are encouraging, demonstrating good efficiencies and robustness
9. Improving Reliability of High Power Quasi-CW Laser Diode Arrays for Pumping Solid State Lasers
Science.gov (United States)
Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Baggott, Renee S.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.
2005-01-01
Most Lidar applications rely on moderate to high power solid state lasers to generate the required transmitted pulses. However, the reliability of solid state lasers, which can operate autonomously over long periods, is constrained by their laser diode pump arrays. Thermal cycling of the active regions is considered the primary reason for rapid degradation of the quasi-CW high power laser diode arrays, and the excessive temperature rise is the leading suspect in premature failure. The thermal issues of laser diode arrays are even more drastic for 2-micron solid state lasers which require considerably longer pump pulses compared to the more commonly used pump arrays for 1-micron lasers. This paper describes several advanced packaging techniques being employed for more efficient heat removal from the active regions of the laser diode bars. Experimental results for several high power laser diode array devices will be reported and their performance when operated at long pulsewidths of about 1msec will be described.
10. Q-switched Ho:YLF laser pumped by a Tm:GdVO4 laser.
CSIR Research Space (South Africa)
Esser, MJD
2009-06-01
Full Text Available The authors have, through careful analysis of spectroscopic data, designed and demonstrated a diode-end-pumped, quasicontinuous wave Tm:GdVO4 laser operating at 1892 nm in order to pump a Q-switched Ho:YLF laser. The Ho:YLF maximum output energy...
11. Design of ultrahigh brightness solar-pumped disk laser.
Science.gov (United States)
Liang, Dawei; Almeida, Joana
2012-09-10
To significantly improve the solar-pumped laser beam brightness, a multi-Fresnel lens scheme is proposed for side-pumping either a single-crystal Nd:YAG or a core-doped ceramic Sm(3+) Nd:YAG disk. Optimum laser system parameters are found through ZEMAX and LASCAD numerical analysis. An ultrahigh laser beam figure of merit B of 53 W is numerically calculated, corresponding to a significant enhancement of more than 180 times over the previous record. 17.7 W/m(2) collection efficiency is also numerically attained. The strong thermal effects that have hampered present-day rod-type solar-pumped lasers can also be largely alleviated.
12. Diode-laser-pump module with integrated signal ports for pumping amplifying fibers and method
Science.gov (United States)
Savage-Leuchs,; Matthias, P [Woodinville, WA
2009-05-26
Apparatus and method for collimating pump light of a first wavelength from laser diode(s) into a collimated beam within an enclosure having first and second optical ports, directing pump light from the collimated beam to the first port; and directing signal light inside the enclosure between the first and second port. The signal and pump wavelengths are different. The enclosure provides a pump block having a first port that emits pump light to a gain fiber outside the enclosure and that also passes signal light either into or out of the enclosure, and another port that passes signal light either out of or into the enclosure. Some embodiments use a dichroic mirror to direct pump light to the first port and direct signal light between the first and second ports. Some embodiments include a wavelength-conversion device to change the wavelength of at least some of the signal light.
13. Bound states of 3He in 3He-4He mixture films
International Nuclear Information System (INIS)
Bashkin, E.; Pavloff, N.; Treiner, J.
1995-01-01
3 He atoms dissolved in superfluid 4 He may form dimers ( 3 He) 2 in two-dimensional (2D) geometries. We study dimer formation in films of dilute 3 He- 4 He mixture. After designing a schematic 3 He- 4 He interaction potential we calculate the dimer binding energy for various substrates. It is shown that 3 He impurity states localized near the substrate give rise to the largest magnitudes of the binding energies
14. High average power diode pumped solid state lasers for CALIOPE
International Nuclear Information System (INIS)
Comaskey, B.; Halpin, J.; Moran, B.
1994-07-01
Diode pumping of solid state media offers the opportunity for very low maintenance, high efficiency, and compact laser systems. For remote sensing, such lasers may be used to pump tunable non-linear sources, or if tunable themselves, act directly or through harmonic crystals as the probe. The needs of long range remote sensing missions require laser performance in the several watts to kilowatts range. At these power performance levels, more advanced thermal management technologies are required for the diode pumps. The solid state laser design must now address a variety of issues arising from the thermal loads, including fracture limits, induced lensing and aberrations, induced birefringence, and laser cavity optical component performance degradation with average power loading. In order to highlight the design trade-offs involved in addressing the above issues, a variety of existing average power laser systems are briefly described. Included are two systems based on Spectra Diode Laboratory's water impingement cooled diode packages: a two times diffraction limited, 200 watt average power, 200 Hz multi-rod laser/amplifier by Fibertek, and TRW's 100 watt, 100 Hz, phase conjugated amplifier. The authors also present two laser systems built at Lawrence Livermore National Laboratory (LLNL) based on their more aggressive diode bar cooling package, which uses microchannel cooler technology capable of 100% duty factor operation. They then present the design of LLNL's first generation OPO pump laser for remote sensing. This system is specified to run at 100 Hz, 20 nsec pulses each with 300 mJ, less than two times diffraction limited, and with a stable single longitudinal mode. The performance of the first testbed version will be presented. The authors conclude with directions their group is pursuing to advance average power lasers. This includes average power electro-optics, low heat load lasing media, and heat capacity lasers
15. Progress in Polarized 3He Ion Source at RCNP
International Nuclear Information System (INIS)
Tanaka, M.; Takahashi, Y.; Shimoda, T.; Yasui, S.; Yosoi, M.; Takahisa, K.; Shimakura, N.; Plis, Yu. A.; Donets, E. D.
2007-01-01
A long history on the polarized 3He ion source developed at RCNP is presented. We started with an 'OPPIS' (Optical Pumping Polarized Ion Source) and later found the fundamental difficulties in the OPPIS. To overcome them an 'EPPIS' (Electron Pumping Polarized Ion Source) was proposed and its validity was experimentally proven. However, a serious technical disadvantage was also found in the EPPIS. To avoid this disadvantage we proposed a new concept, 'SEPIS' (Spin Exchange Polarized Ion Source), which uses an enhanced spin-exchange cross section theoretically expected at low 3He+ incident energies in the 3He+ + Rb system. Next, we describe the present status of the SEPIS development: construction of a bench test device allowing the measurements of not only the spin-exchange cross sections σse but also the electron capture cross sections σec for the 3He+ + Rb system. The latest experimental data on σec are presented and compared with other previous experimental data and the theoretical calculations.Finally, a design study of the SEPIS for practical use in nuclear (cyclotron) and particle physics (synchrotron) is shortly mentioned
16. Laser-diode pumped 40-W Yb:YAG ceramic laser.
Science.gov (United States)
Hao, Qiang; Li, Wenxue; Pan, Haifeng; Zhang, Xiaoyi; Jiang, Benxue; Pan, Yubai; Zeng, Heping
2009-09-28
We demonstrated a high-power continuous-wave (CW) polycrystalline Yb:YAG ceramic laser pumped by fiber-pigtailed laser diode at 968 nm with 400 mum fiber core. The Yb:YAG ceramic laser performance was compared for different Yb(3+) ion concentrations in the ceramics by using a conventional end-pump laser cavity consisting of two flat mirrors with output couplers of different transmissions. A CW laser output of 40 W average power with M(2) factor of 5.8 was obtained with 5 mol% Yb concentration under 120 W incident pump power. This is to the best of our knowledge the highest output power in end-pumped bulk Yb:YAG ceramic laser.
17. Potential of solar-simulator-pumped alexandrite lasers
Science.gov (United States)
Deyoung, Russell J.
1990-01-01
An attempt was made to pump an alexandrite laser rod using a Tamarak solar simulator and also a tungsten-halogen lamp. A very low optical laser cavity was used to achieve the threshold minimum pumping-power requirement. Lasing was not achieved. The laser threshold optical-power requirement was calculated to be approximately 626 W/sq cm for a gain length of 7.6 cm, whereas the Tamarak simulator produces 1150 W/sq cm over a gain length of 3.3 cm, which is less than the 1442 W/sq cm required to reach laser threshold. The rod was optically pulsed with 200 msec pulses, which allowed the alexandrite rod to operate at near room temperature. The optical intensity-gain-length product to achieve laser threshold should be approximately 35,244 solar constants-cm. In the present setup, this product was 28,111 solar constants-cm.
18. Neutron scattering lengths of 3He
International Nuclear Information System (INIS)
Alfimenkov, V.P.; Akopian, G.G.; Wierzbicki, J.; Govorov, A.M.; Pikelner, L.B.; Sharapov, E.I.
1976-01-01
The total neutron scattering cross-section of 3 He has been measured in the neutron energy range from 20 meV to 2 eV. Together with the known value of coherent scattering amplitude it leads to the two sts of n 3 He scattering lengths
19. BRIEF COMMUNICATIONS: Optically pumped ultraviolet BR2 laser
Science.gov (United States)
Kamrukov, A. S.; Kozlov, N. P.; Protasov, Yu S.; Ushmarov, E. Yu
1989-12-01
A report is given of lasing achieved for the first time in optically pumped molecular bromine (D' 3Π2g→A' 3π2u, λL approx 292 nm). It was pumped by thermal vacuum ultraviolet radiation emitted by plasmadynamic discharges of magnetoplasma compressors, formed directly in the laser active medium. An output energy of ~ 1.1 J was obtained per laser pulse of ~ 5-μs duration from a Br2:Ar approx 1:450 active mixture at a pressure of ~ 4 atm. A comparison was made of the experimental output parameters of optically pumped Br2, I2, and XeF (B-X) lasers when their geometries and excitation energies were identical.
20. A cladding-pumped, tunable holmium doped fiber laser.
Science.gov (United States)
Simakov, Nikita; Hemming, Alexander; Clarkson, W Andrew; Haub, John; Carter, Adrian
2013-11-18
We present a tunable, high power cladding-pumped holmium doped fiber laser. The laser generated >15 W CW average power across a wavelength range of 2.043 - 2.171 μm, with a maximum output power of 29.7 W at 2.120 μm. The laser also produced 18.2 W when operating at 2.171 µm. To the best of our knowledge this is the highest power operation of a holmium doped laser at a wavelength >2.15 µm. We discuss the significance of background losses and fiber design for achieving efficient operation in holmium doped fibers.
1. Optically pumped semiconductor lasers for atomic and molecular physics
Science.gov (United States)
Burd, S.; Leibfried, D.; Wilson, A. C.; Wineland, D. J.
2015-03-01
Experiments in atomic, molecular and optical (AMO) physics rely on lasers at many different wavelengths and with varying requirements on spectral linewidth, power and intensity stability. Optically pumped semiconductor lasers (OPSLs), when combined with nonlinear frequency conversion, can potentially replace many of the laser systems currently in use. We are developing a source for laser cooling and spectroscopy of Mg+ ions at 280 nm, based on a frequency quadrupled OPSL with the gain chip fabricated at the ORC at Tampere Univ. of Technology, Finland. This OPSL system could serve as a prototype for many other sources used in atomic and molecular physics.
2. Direct pumping of ultrashort Ti:sapphire lasers by a frequency doubled diode laser
DEFF Research Database (Denmark)
Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika
2011-01-01
electro-optical efficiency of the diode laser. Autocorrelation measurements show that pulse widths of less than 20 fs can be expected with an average power of 52 mW when using our laser. These results indicate the high potential of direct diode laser pumped Ti: sapphire lasers to be used in applications....... When using our diode laser system, the optical conversion efficiencies from green to near-infrared light reduces to 75 % of the values achieved with the commercial pump laser. Despite this reduction the overall efficiency of the Ti: sapphire laser is still increased by a factor > 2 due to the superior...... like retinal optical coherence tomography (OCT) or pumping of photonic crystal fibers for CARS (coherent anti-stokes Raman spectroscopy) microscopy....
3. Electron beam pumped KrF lasers for fusion energy
International Nuclear Information System (INIS)
Sethian, J.D.; Friedman, M.; Giuliani, J.L. Jr.; Lehmberg, R.H.; Obenschain, S.P.; Kepple, P.; Wolford, M.; Hegeler, F.; Swanekamp, S.B.; Weidenheimer, D.; Welch, D.; Rose, D.V.; Searles, S.
2003-01-01
In this paper, we describe the development of electron beam pumped KrF lasers for inertial fusion energy. KrF lasers are an attractive driver for fusion, on account of their demonstrated very high beam quality, which is essential for reducing imprint in direct drive targets; their short wavelength (248 nm), which mitigates the growth of plasma instabilities; and their modular architecture, which reduces development costs. In this paper we present a basic overview of KrF laser technology as well as current research and development in three key areas: electron beam stability and transport; KrF kinetics and laser propagation; and pulsed power. The work will be cast in context of the two KrF lasers at the Naval Research Laboratory, The Nike Laser (5 kJ, single shot), and The Electra Laser (400-700 J repetitively pulsed)
4. The ISOLDE RILIS pump laser upgrade and the LARIS Laboratory
International Nuclear Information System (INIS)
Marsh, B. A.; Berg, L.-E.; Fedorov, D. V.; Fedosseev, V. N.; Launila, O. J.; Lindroos, M.; Losito, R.; Osterdahl, F. K.; Pauchard, T.; Pohjalainen, I. T.; Sassenberg, U.; Seliverstov, M. D.; Sjoedin, A. M.; Transtroemer, G.
2010-01-01
On account of its high efficiency, speed and unmatched selectivity, the Resonance Ionization Laser Ion Source (RILIS) is the preferred method for ionizing the nuclear reaction products at the ISOLDE on-line isotope separator facility. By exploiting the unique electronic energy level 'fingerprint' of a chosen element, the RILIS process of laser step-wise resonance ionization enables an ion beam of high chemical purity to be sent through the mass selective separator magnet. The isobaric purity of a beam of a chosen isotope is therefore greatly increased. The RILIS, comprising of up to three frequency tunable pulsed dye lasers has been upgraded with the installation of a Nd:YAG pump laser as a replacement for the old Copper Vapor Laser (CVL) system. A summary of the current Nd:YAG pumped RILIS performance is given. To accompany the RILIS pump laser upgrade, a new ionization scheme for manganese has been developed at the newly constructed LAser Resonance Ionization Spectroscopy (LARIS) laboratory and successfully applied for on-line RILIS operation. An overview of the LARIS facility is given along with details of the ionization scheme development work for manganese.
5. Scaling of an Optically Pumped Mid-Infrared Rubidium Laser
Science.gov (United States)
2015-03-26
beam, and the saturation intensity, Isat , was calculated using Equation 4.6: = ℎ( + ) , (6) where h is the...4.91 mm2, the intensity of the laser at a pump energy of 0.05 mJ was 10.2 mW/cm2. Thus I/ Isat ~ 290, so ∆νsat should have been about 17 times... Isat ~ 5796, so ∆νsat should have been about 76∆νD, in reasonable agreement with the experimental result of 53∆νD. Rb Laser Output Energy vs. Pump
6. Kerr-lens mode-locked Ti:Sapphire laser pumped by a single laser diode
Science.gov (United States)
Kopylov, D. A.; Esaulkov, M. N.; Kuritsyn, I. I.; Mavritskiy, A. O.; Perminov, B. E.; Konyashchenko, A. V.; Murzina, T. V.; Maydykovskiy, A. I.
2018-04-01
The performance of a Ti:sapphire laser pumped by a single 461 nm laser diode is presented for both the continuous-wave and the mode-locked regimes of operation. We introduce a simple astigmatism correction scheme for the laser diode beam consisting of two cylindrical lenses affecting the pump beam along the fast axis of the laser diode, which provides the mode-matching between the nearly square-shaped pump beam and the cavity mode. The resulting efficiency of the suggested Ti:Sapphire oscillator pumped by such a laser diode is analyzed for the Ti:sapphire crystals of 3 mm, 5 mm and 10 mm in length. We demonstrate that such a system provides the generation of ultrashort pulses up to 15 fs in duration with the repetition rate of 87 MHz, the average power being 170 mW.
7. Development of Cr,Nd:GSGG laser as a pumping source of Ti:sapphire laser
International Nuclear Information System (INIS)
Tamura, Koji; Arisawa, Takashi
1999-08-01
Since efficiency of Cr,Nd doped gadolinium scandium gallium garnet (GSGG) laser is in principle higher than that of Nd:YAG laser, it can be a highly efficient pumping source for Ti:sapphire laser. We have made GSGG laser, and measured its oscillation properties. It was two times more efficient than Nd:YAG laser at free running mode operation. At Q-switched mode operation, fundamental output of 50 mJ and second harmonics output of 8 mJ were obtained. The developed laser had appropriate spatial profile, temporal duration, long time stability for solid laser pumping. Ti:sapphire laser oscillation was achieved by the second harmonics of GSGG laser. (author)
8. Solar-simulator-pumped atomic iodine laser kinetics
Science.gov (United States)
Wilson, H. W.; Raju, S.; Shiu, Y. J.
1983-01-01
The literature contains broad ranges of disagreement in kinetic data for the atomic iodine laser. A kinetic model of a solar-simulator-pumped iodine laser is used to select those kinetic data consistent with recent laser experiments at the Langley Research Center. Analysis of the solar-simulator-pumped laser experiments resulted in the following estimates of rate coefficients: for alkyl radical (n-C3F7) and atomic iodine (I) recombination, 4.3 x 10 to the 11th power (1.9) + or - cu cm/s; for n-C3F7I stabilized atomic iodine recombination (I + I) 3.7 x 10 to the -32nd power (2.3) + or -1 cm to the 6th power/s; and for molecular iodine (I2) quenching, 3.1 x 10 to the -11th power (1.6) + or - 1 cu cm/s. These rates are consistent with the recent measurements.
9. Quantitative pump-induced wavefront distortions in laser-diode- and flash-lamp-pumped Nd:YLF laser rods
International Nuclear Information System (INIS)
Skeldon, M.D.; Saager, R.B.; Seka, W.
1999-01-01
Detailed interferometric measurements of the induced thermal distortions due to laser-diode and xenon flashlamp pumping of Nd:YLF are presented. The thermal distortions are quantified in terms of the primary aberrations of defocus, astigmatism, coma, and spherical. Defocus and astigmatism are shown to dominate the thermal aberrations. The measured defocus and astigmatism are converted to the conventional thermal-focal lengths in two perpendicular directions with respect to the Nd:YLF crystalline c axis for each of the two polarization states σ and π. A comparison of the thermal-focal lengths measured with the xenon flashlamp- and laser-diode-pumped rods is given when the rods are pumped to the same small-signal gain. The authors calculate effective dioptric-power coefficients from the data for comparison to those reported in the literature for krypton-flashlamp pumping. A thermal-time constant of 1.5 s is measured for the laser-diode-pumped Nd:YLF laser rod
10. Cladding for transverse-pumped solid-state laser
Science.gov (United States)
Byer, Robert L. (Inventor); Fan, Tso Y. (Inventor)
1989-01-01
In a transverse pumped, solid state laser, a nonabsorptive cladding surrounds a gain medium. A single tranverse mode, namely the Transverse Electromagnetic (TEM) sub 00 mode, is provided. The TEM sub 00 model has a cross sectional diameter greater than a transverse dimension of the gain medium but less than a transverse dimension of the cladding. The required size of the gain medium is minimized while a threshold for laser output is lowered.
11. Discharge pumped F/sub 2/ laser at 1580 A
Energy Technology Data Exchange (ETDEWEB)
Pummer, H; Hohla, K; Diegelmann, M; Reilly, J P
1979-01-01
By pumping mixtures of F/sub 2/ and He in a fast uv-preionized discharge laser emission at 1578 A, probably stemming from the /sup 3/PI/sub 2g/ ..-->.. /sup 3/PI/sub 2u/ transition in molecular fluorine have been obtained. Observed energy is 8.5 mJ in pulses of 15 ns half-width. First experimental results on laser performance and scalability are given.
12. Solar Pumped High Power Solid State Laser for Space Applications
Science.gov (United States)
Fork, Richard L.; Laycock, Rustin L.; Green, Jason J. A.; Walker, Wesley W.; Cole, Spencer T.; Frederick, Kevin B.; Phillips, Dane J.
2004-01-01
Highly coherent laser light provides a nearly optimal means of transmitting power in space. The simplest most direct means of converting sunlight to coherent laser light is a solar pumped laser oscillator. A key need for broadly useful space solar power is a robust solid state laser oscillator capable of operating efficiently in near Earth space at output powers in the multi hundred kilowatt range. The principal challenges in realizing such solar pumped laser oscillators are: (1) the need to remove heat from the solid state laser material without introducing unacceptable thermal shock, thermal lensing, or thermal stress induced birefringence to a degree that improves on current removal rates by several orders of magnitude and (2) to introduce sunlight at an effective concentration (kW/sq cm of laser cross sectional area) that is several orders of magnitude higher than currently available while tolerating a pointing error of the spacecraft of several degrees. We discuss strategies for addressing these challenges. The need to remove the high densities of heat, e.g., 30 kW/cu cm, while keeping the thermal shock, thermal lensing and thermal stress induced birefringence loss sufficiently low is addressed in terms of a novel use of diamond integrated with the laser material, such as Ti:sapphire in a manner such that the waste heat is removed from the laser medium in an axial direction and in the diamond in a radial direction. We discuss means for concentrating sunlight to an effective areal density of the order of 30 kW/sq cm. The method integrates conventional imaging optics, non-imaging optics and nonlinear optics. In effect we use a method that combines some of the methods of optical pumping solid state materials and optical fiber, but also address laser media having areas sufficiently large, e.g., 1 cm diameter to handle the multi-hundred kilowatt level powers needed for space solar power.
13. Neutron polarization in polarized 3He targets
International Nuclear Information System (INIS)
Friar, J.L.; Gibson, B.F.; Payne, G.L.; Bernstein, A.M.; Chupp, T.E.
1990-01-01
Simple formulas for the neutron and proton polarizations in polarized 3 He targets are derived assuming (1) quasielastic final states; (2) no final-state interactions; (3) no meson-exchange currents; (4) large momentum transfers; (5) factorizability of 3 He SU(4) response-function components. Numerical results from a wide variety of bound-state solutions of the Faddeev equations are presented. It is found that this simple model predicts the polarization of neutrons in a fully polarized 3 He target to be 87%, while protons should have a slight residual polarization of -2.7%. Numerical studies show that this model works very well for quasielastic electron scattering
14. Optical vortex generation from a diode-pumped alexandrite laser
Science.gov (United States)
Thomas, G. M.; Minassian, A.; Damzen, M. J.
2018-04-01
We present the demonstration of an optical vortex mode directly generated from a diode-pumped alexandrite slab laser, operating in the bounce geometry. This is the first demonstration of an optical vortex mode generated from an alexandrite laser or from any other vibronic laser. An output power of 2 W for a vortex mode with a ‘topological charge’ of 1 was achieved and the laser was made to oscillate with both left- and right-handed vorticity. The laser operated at two distinct wavelengths simultaneously, 755 and 759 nm, due to birefringent filtering in the alexandrite gain medium. The result offers the prospect of broadly wavelength tunable vortex generation directly from a laser.
15. Experiments on resonantly photo-pumped x-ray lasers
International Nuclear Information System (INIS)
Nilsen, J.; Porter, J.L.; Da Silva, L.B.; MacGowan, B.; Beiersdorfer, P..; Elliott, S.R.; Young, B.K.
1992-01-01
We describe our recent effort to identify and study a promising resonantly photopumped x-ray laser scheme. In particular we will describe a scheme which uses the strong emission lines of a nickel-like ion to resonantly photo-pump a neon-like ion and enhance the lasing of the neon-like 3p → 3s transitions
16. Efficient diode pumped ytterbium-doped fibre laser
Czech Academy of Sciences Publication Activity Database
Harun, S.W.; Paul, M.C.; Moghaddam, M.R.A.; Das, S.; Sen, R.; Dhar, Anirban; Pal, M.; Bhadra, S.K.; Ahmad, H.
2010-01-01
Roč. 46, č. 1 (2010), s. 68-69 ISSN 0013-5194 Institutional research plan: CEZ:AV0Z20670512 Keywords : Fibre lasers * Oscillator * Diode-pumped Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.001, year: 2010
17. 3He electron scattering sum rules
International Nuclear Information System (INIS)
Kim, Y.E.; Tornow, V.
1982-01-01
Electron scattering sum rules for 3 He are derived with a realistic ground-state wave function. The theoretical results are compared with the experimentally measured integrated cross sections. (author)
18. Efficient Ho:YLF laser pumped by a Tm:fiber laser
CSIR Research Space (South Africa)
Koen, W
2013-07-01
Full Text Available Laser sources emitting in the 2 micron region is of particular interest for applications in medicine, remote sensing (LIDAR) and directed infra-red countermeasures. In addition, they are also desirable pump sources for efficient optical parametric...
19. Traveling-wave laser-produced-plasma energy source for photoionization laser pumping and lasers incorporating said
Science.gov (United States)
Sher, Mark H.; Macklin, John J.; Harris, Stephen E.
1989-09-26
A traveling-wave, laser-produced-plasma, energy source used to obtain single-pass gain saturation of a photoionization pumped laser. A cylindrical lens is used to focus a pump laser beam to a long line on a target. Grooves are cut in the target to present a surface near normal to the incident beam and to reduce the area, and hence increase the intensity and efficiency, of plasma formation.
20. Optical pumping of Rb by Ti:Sa laser and high-power laser diode
Czech Academy of Sciences Publication Activity Database
Buchta, Zdeněk; Rychnovský, Jan; Lazar, Josef
2006-01-01
Roč. 8, č. 1 (2006), s. 350-354 ISSN 1454-4164 R&D Projects: GA AV ČR IAA1065303; GA ČR GA102/04/2109 Institutional research plan: CEZ:AV0Z20650511 Keywords : optical pumping * Ti:Sa laser * laser diode * emission linewidth * spectroscopy * laser frequency stabilization Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.106, year: 2006
1. Distributed feedback dye laser pumped with copper-vapor laser emission
Energy Technology Data Exchange (ETDEWEB)
Mirza, S Yu; Soldatov, A N; Sukhanov, V B
1983-10-01
The power-spectrum characteristics of the emission of a distributed feedback dye laser pumped with a copper vapor laser have been studied. Laser action has been observed in five dyes over a tuning range of 530-723 nm with an efficiency of 12.4%. The specfic features of the distributed feedback dye laser operating at pulse repetition rates of 4 kHz are discussed.
2. Highly efficient solar-pumped Nd:YAG laser.
Science.gov (United States)
Liang, Dawei; Almeida, Joana
2011-12-19
The recent progress in solar-pumped laser with Fresnel lens and Cr:Nd:YAG ceramic medium has revitalized solar laser researches, revealing a promising future for renewable reduction of magnesium from magnesium oxide. Here we show a big advance in solar laser collection efficiency by utilizing an economical Fresnel lens and a most widely used Nd:YAG single-crystal rod. The incoming solar radiation from the sun is focused by a 0.9 m diameter Fresnel lens. A dielectric totally internally reflecting secondary concentrator is employed to couple the concentrated solar radiation from the focal zone to a 4 mm diameter Nd:YAG rod within a conical pumping cavity. 12.3 W cw laser power is produced, corresponding to 19.3 W/m(2) collection efficiency, which is 2.9 times larger than the previous results with Nd:YAG single-crystal medium. Record-high slope efficiency of 3.9% is also registered. Laser beam quality is considerably improved by pumping a 3 mm diameter Nd:YAG rod.
3. Magnetic composite Hydrodynamic Pump with Laser Induced Graphene Electrodes
KAUST Repository
Khan, Mohammed Asadullah; Hristovski, Ilija R.; Marinaro, Giovanni; Kosel, Jü rgen
2017-01-01
A polymer based magneto hydrodynamic pump capable of actuating saline fluids is presented. The benefit of this pumping concept to operate without any moving parts is combined with simple and cheap fabrication methods and a magnetic composite material, enabling a high level of integration. The operating principle, fabrication methodology and flow characteristics of the pump are detailed. The pump electrodes are created by laser printing of polyimide, while the permanent magnet is molded from an NdFeB powder - polydimethylsiloxane (PDMS) composite. The cross-section area of the pump is 240 mm $^2$ . The electrode length is 5 mm. The magnetic characteristics of the NdFeB-PDMS composite indicate high degree of magnetization, which increases the pump efficiency. Using a saline solution similar to seawater, the pump produces 3.4 mm/s flow velocity at a voltage of 7.5V and a current density of 30 mA/cm $^2$ .
4. Magnetic composite Hydrodynamic Pump with Laser Induced Graphene Electrodes
KAUST Repository
2017-05-24
A polymer based magneto hydrodynamic pump capable of actuating saline fluids is presented. The benefit of this pumping concept to operate without any moving parts is combined with simple and cheap fabrication methods and a magnetic composite material, enabling a high level of integration. The operating principle, fabrication methodology and flow characteristics of the pump are detailed. The pump electrodes are created by laser printing of polyimide, while the permanent magnet is molded from an NdFeB powder - polydimethylsiloxane (PDMS) composite. The cross-section area of the pump is 240 mm $^2$ . The electrode length is 5 mm. The magnetic characteristics of the NdFeB-PDMS composite indicate high degree of magnetization, which increases the pump efficiency. Using a saline solution similar to seawater, the pump produces 3.4 mm/s flow velocity at a voltage of 7.5V and a current density of 30 mA/cm $^2$ .
5. High-power diode laser bars as pump sources for fiber lasers and amplifiers (Invited Paper)
Science.gov (United States)
Bonati, G.; Hennig, P.; Wolff, D.; Voelckel, H.; Gabler, T.; Krause, U.; T'nnermann, A.; Reich, M.; Limpert, J.; Werner, E.; Liem, A.
2005-04-01
Fiber lasers are pumped by fibercoupled, multimode single chip devices at 915nm. That"s what everybody assumes when asked for the type of fiber laser pumps and it was like this for many years. Coming up as an amplifier for telecom applications, the amount of pump power needed was in the range of several watts. Highest pump powers for a limited market entered the ten watts range. This is a range of power that can be covered by highly reliable multimode chips, that have to survive up to 25 years, e.g. in submarine applications. With fiber lasers entering the power range and the application fields of rod and thin disc lasers, the amount of pump power needed raised into the area of several hundred watts. In this area of pump power, usually bar based pumps are used. This is due to the much higher cost pressure of the industrial customers compared to telecom customers. We expect more then 70% of all industrial systems to be pumped by diode laser bars. Predictions that bar based pumps survive for just a thousand hours in cw-operation and fractions of this if pulsed are wrong. Bar based pumps have to perform on full power for 10.000h on Micro channel heat sinks and 20.000h on passive heatsinks in industrial applications, and they do. We will show a variety of data, "real" long time tests and statistics from the JENOPTIK Laserdiode as well as data of thousands of bars in the field, showing that bar based pumps are not just well suitable for industrial applications on high power levels, but even showing benefits compared to chip based pumps. And it"s reasonable, that the same objectives of cost effectiveness, power and lifetime apply as well to thin disc, rod and slab lasers as to fiber lasers. Due to the pumping of fiber lasers, examples will be shown, how to utilize bars for high brightness fiber coupling. In this area, the automation is on its way to reduce the costs on the fibercoupling, similar to what had been done in the single chip business. All these efforts are
6. Electrically pumped edge-emitting photonic bandgap semiconductor laser
Science.gov (United States)
Lin, Shawn-Yu; Zubrzycki, Walter J.
2004-01-06
A highly efficient, electrically pumped edge-emitting semiconductor laser based on a one- or two-dimensional photonic bandgap (PBG) structure is described. The laser optical cavity is formed using a pair of PBG mirrors operating in the photonic band gap regime. Transverse confinement is achieved by surrounding an active semiconductor layer of high refractive index with lower-index cladding layers. The cladding layers can be electrically insulating in the passive PBG mirror and waveguide regions with a small conducting aperture for efficient channeling of the injection pump current into the active region. The active layer can comprise a quantum well structure. The quantum well structure can be relaxed in the passive regions to provide efficient extraction of laser light from the active region.
7. Design of a solar-pumped frequency-doubled 532 nm Nd:YVO4 laser
Science.gov (United States)
Kittiboonanan, P.; Putchana, W.; Deeudomand, M.; Ratanavis, A.
2017-09-01
During the last year we have made progresson a development of a frequency-doubled 532 nm Nd:YVO4 laser pumped by solar light. The research aimed to demonstrate solar pumped lasers consisting of the optically contracted Nd:YVO4 crystal and KTP crystal with a system of laser mirrors deposited onto crystal sides. The Cassegrain reflector is used as the configuration. This solar pumped laser system is appealing for a variety applications including laser communication, imaging and defense applications.
8. Towards shorter wavelength x-ray lasers using a high power, short pulse pump laser
International Nuclear Information System (INIS)
Tighe, W.; Krushelnick, K.; Valeo, E.; Suckewer, S.
1991-05-01
A near-terawatt, KrF* laser system, focussable to power densities >10 18 W/cm 2 has been constructed for use as a pump laser in various schemes aimed at the development of x-ray lasing below 5nm. The laser system along with output characteristics such as the pulse duration, the focal spot size, and the percentage of amplified spontaneous emission (ASE) emitted along with the laser pulse will be presented. Schemes intended to lead to shorter wavelength x-ray emission will be described. The resultant requirements on the pump laser characteristics and the target design will be outlined. Results from recent solid target experiments and two-laser experiments, showing the interaction of a high-power, short pulse laser with a preformed plasma, will be presented. 13 refs., 5 figs
9. Optically Pumped Carbon Monoxide Cascade Laser
National Research Council Canada - National Science Library
Sawruk, Nicholas W
2005-01-01
...) overtone band of the CO, which induced lasing on the (3,2) and (2,1) bands around 4.7um. The laser output was spectrally separated to determine the spectral and temporal evolution of the CO lasing pulse...
10. Photodisintegration of 3H and 3He
International Nuclear Information System (INIS)
Faul, D.D.
1980-09-01
The photoneutron cross sections for 3 H and 3 He have been measured from threshold to approx. 25 MeV with monoenergetic photons from the annihilation in flight of fast positrons at the LLL Electron-Positron Linear Accelerator facility. These reactions include the two-body breakup of 3 H and the three-body breakup of both 3 H and 3 He; these measurements for 3 H are the first to span the energy region across the peaks of the cross sections. An efficient BF 3 -tube-and-paraffin neutron detector and high-pressure gaseous samples of several moles each (the activity of the 3 H sample was approx. 200,000 Ci) were employed in these measurements. Measurements on 16 O and 2 H also were performed to verify the absolute cross-section scale. The results, when compared with each other and with results for the two-body breakup cross section for 3 He from the literature, show that the two-body breakup cross sections for 3 H and 3 He have nearly the same shape, but the one for 3 He lies lower in magnitude; the three-body breakup cross section for 3 He lies higher in magnitude and is broader in the peak region and also rises less sharply from threshold than that for 3 H; and these measured differences between the cross sections for the breakup modes largely compensate in their sum, so that the total photon absorption cross sections for 3 H and 3 He are nearly the same in both size and shape at energies near and above their peaks. Theoretical results from the literature disagree with the experimental results to a certain extent over the entire photon-energy region for which the photoneutron cross sections were measured. 50 figures, 7 tables
11. Optimum transmission for a 3He neutron polarizer
International Nuclear Information System (INIS)
Tasset, F.; Ressouche, E.
1995-01-01
Following recent achievements in polarizing gaseous 3 He targets by optical pumping at room temperature, polarized helium-3 is now the most promising polarizer for thermal and epithermal neutrons and should soon compete favorably with existing Heusler polarizing crystals. Because it is gaseous, a degree of freedom exists in such a filter: the pressure of the gas in the cell. This parameter allows a choice to be made in the filter design: for a given polarization of 3 He, one is able to increase the pressure, to favor neutron beam polarization, or to stay at relatively low pressure to favor the filter's transmission. In this paper, we discuss this point in the framework of a classical polarized neutron experiment, and we compare our more general results with the quality factor Q=P√(T), which is generally taken as standard for such a filter. (orig.)
12. Femtosecond Cr:LiSAF and Cr:LiCAF lasers pumped by tapered diode lasers.
Science.gov (United States)
Demirbas, Umit; Schmalz, Michael; Sumpf, Bernd; Erbert, Götz; Petrich, Gale S; Kolodziejski, Leslie A; Fujimoto, James G; Kärtner, Franz X; Leitenstorfer, Alfred
2011-10-10
We report compact, low-cost and efficient Cr:Colquiriite lasers that are pumped by high brightness tapered laser diodes. The tapered laser diodes provided 1 to 1.2 W of output power around 675 nm, at an electrical-to-optical conversion efficiency of about 30%. Using a single tapered diode laser as the pump source, we have demonstrated output powers of 500 mW and 410 mW together with slope efficiencies of 47% and 41% from continuous wave (cw) Cr:LiSAF and Cr:LiCAF lasers, respectively. In cw mode-locked operation, sub-100-fs pulse trains with average power between 200 mW and 250 mW were obtained at repetition rates around 100 MHz. Upon pumping the Cr:Colquiriite lasers with two tapered laser diodes (one from each side of the crystal), we have observed scaling of cw powers to 850 mW in Cr:LiSAF and to 650 mW in Cr:LiCAF. From the double side pumped Cr:LiCAF laser, we have also obtained ~220 fs long pulses with 5.4 nJ of pulse energy at 77 MHz repetition rate. These are the highest energy levels reported from Cr:Colquiriite so far at these repetition rates. Our findings indicate that tapered diodes in the red spectral region are likely to become the standard pump source for Cr:Colquiriite lasers in the near future. Moreover, the simplified pumping scheme might facilitate efficient commercialization of Cr:Colquiriite systems, bearing the potential to significantly boost applications of cw and femtosecond lasers in this spectral region (750-1000 nm).
13. Copper vapour laser with an efficient semiconductor pump generator having comparable pump pulse and output pulse durations
Energy Technology Data Exchange (ETDEWEB)
Yurkin, A A [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
2016-03-31
We report the results of experimental studies of a copper vapour laser with a semiconductor pump generator capable of forming virtually optimal pump pulses with a current rise steepness of about 40 A ns{sup -1} in a KULON LT-1.5CU active element. To maintain the operating temperature of the active element's channel, an additional heating pulsed oscillator is used. High efficiency of the pump generator is demonstrated. (lasers)
14. Cosmogenic 3He in detrital gold
Science.gov (United States)
Stuart, Finlay; Yakubovich, Olga; Caracedo, Ana; Nesterenok, Alexander
2017-04-01
Since the measurement of cosmogenic He in an alluvial diamond by McConville and Reynolds (1996) the application of cosmogenic noble gases to individual detrital grains to quantify surface processes has not been vigorously pursued. The likely low rate of diffusion of cosmogenic He in native metals, and their resistance to weathering and disintegration during erosion and transport, makes them a potential record of long-term Earth surface processes. In an effort to assess the extent that detrital refractory metals record the exposure history during transport and storage we have undertaken a reconnaissance study of the He isotope composition in 18 grains (2-200 mg) of native gold, copper, silver, and PtPd, Pt3Fe and OsIr alloys from alluvial placer deposits from around the world. 4He is dominantly the result of U and Th decay within the grains, or decay of 190Pt in the Pt-rich alloys. 3He is measurable in 13 grains, concentrations range up to 2.7E+6 atoms/g. 3He/4He are always in excess of the crustal radiogenic ratio, up to 306 Ra. Although nucleogenic 3He produced by (n,α) reactions on 6Li, and 3He from trapped hydrothermal fluids, are present, the majority of the 3He is cosmogenic in origin. Using newly calculated cosmogenic 3He production rates in heavy metals, and a determination of the effect of implantation based on the stopping distances of spallogenic 3He and 3H, the grains have 3Hecos concentrations that are equivalent to 0.35 to 1.5 Ma exposure at Earth's surface. In a study of detrital gold grains from several sites in Scotland we have found that 10 % have 3He concentrations that are significantly in excess of that generated since the Last Glacial Maximum. These studies demonstrate that, with refinement, cosmogenic 3He in refractory detrital minerals can be used to quantify sediment transport and storage on the 1-10 Ma timescale. P. McConville & J.H. Reynolds (1989). Geochim. Cosmochim. Acta, 53, 2365-75.
15. 3He Abundances in Planetary Nebulae
Science.gov (United States)
Guzman-Ramirez, Lizette
2017-10-01
Determination of the 3He isotope is important to many fields of astrophysics, including stellar evolution, chemical evolution, and cosmology. The isotope is produced in stars which evolve through the planetary nebula phase. Planetary nebulae are the final evolutionary phase of low- and intermediate-mass stars, where the extensive mass lost by the star on the asymptotic giant branch is ionised by the emerging white dwarf. This ejecta quickly disperses and merges with the surrounding ISM. 3He abundances in planetary nebulae have been derived from the hyperfine transition of the ionised 3He, 3He+, at the radio rest frequency 8.665 GHz. 3He abundances in PNe can help test models of the chemical evolution of the Galaxy. Many hours have been put into trying to detect this line, using telescopes like the Effelsberg 100m dish of the Max Planck Institute for Radio Astronomy, the National Radio Astronomy Observatory (NRAO) 140-foot telescope, the NRAO Very Large Array, the Arecibo antenna, the Green Bank Telescope, and only just recently, the Deep Space Station 63 antenna from the Madrid Deep Space Communications Complex.
16. Diode pumped cascade Er:Y2O3 laser
International Nuclear Information System (INIS)
Sanamyan, T
2015-01-01
A cascade, diode-pumped, continuous wave (CW), dual-wavelength operation in a 0.5% Er 3+ :Y 2 O 3 cryogenic ceramic laser is demonstrated for the first time. The laser operates on cascaded Er ( 4 I 11/2 → 4 I 13/2 → 4 I 15/2 ) transitions and can deliver 24 and 13 W at 1.6 and 2.7 μm, respectively. The overall efficiency with respect to the absorbed ∼980 nm power was 62%. This is, to our best knowledge, the first demonstration of an efficient, high power, cascade, erbium laser achieved in bulk solid-state lasers. The analysis of the output power, the laser’s wavelengths and slope efficiency for each individual laser transition are presented for pure CW operation mode. Also presented are the temporal behaviors of each laser line as a function of pump pulse duration in the quasi-CW regime. (letter)
17. Krypton excimer laser oscillation by discharge pumping
International Nuclear Information System (INIS)
Shirai, Takahiro; Tabe, Yoshitaka; Kubodera, Shoichi; Sasaki, Wataru; Kawanaka, Junji
2001-01-01
We have demonstrated vacuum ultraviolet (VUV) laser oscillation of the krypton excimer (Kr 2 *) excited by a compact self-sustained discharge device. We have observed a spectral narrowing of the Kr 2 * emission centered at 147.8 nm. A deconvoluted spectral width is 0.5 nm (FWHM), which reveals a contrast to a 13 nm spectral width of the spontaneous emission. The Kr 2 * intensity has increased one order of magnitude when a charging voltage was increased larger than 29 kV. The success of the lasing in the VUV spectral region has been attributed to the success of a stable glow discharge of Kr at 10 atm. The pulse width of the VUV laser radiation is 400 ns (FWHM). The maximum output energy measured is as large as 150 μJ. (author)
18. Electric-discharge-pumped nitrogen ion laser
Science.gov (United States)
Laudenslager, J. B.; Pacala, T. J.; Wittig, C.
1976-01-01
The routine operation is described of an N2(+) laser oscillating on the first negative band system of N2(+) which is produced in a preionized transverse discharge device. The discharge design incorporates features which favor the efficient production of the excitation transfer reaction of He2(+) with N2. A capacitive discharge switched by means of a high-current grounded grid thyratron is used to meet the design requirement of a volumetric discharge in high-pressure gas mixtures where the electric discharge need not have an ultrafast rise time (greater than 10 nsec) but should be capable of transferring large quantities of stored electric energy to the gas. A peak power of 180 kW in an 8-nsec laser pulse was obtained with a 0.1% mixture of N2 in helium at a total pressure of 3 atm. The most intense laser oscillations were observed on the (0,1) vibrational transition at 427.8 microns.
19. Investigation of diode-laser pumped thulium-doped fluoride lasers
International Nuclear Information System (INIS)
Matos, Paulo Sergio Fabris de
2006-01-01
Tunable lasers emitting around 2.3 mum region are important in many areas, like gas detection, remote sensing and medical applications. Thulium has a large emission spectra around 2.3 mum with demonstrated tuning range of 2.2-2.45 mum using the YLF host. For efficient pump absorption, a high concentration sensitizer like ytterbium can be used. We demonstrate quasi-cw operation of the Yb:Tm:YLF laser, pumped at 960 nm with a 20 W diode bar achieving the highest output power reported so far of 620 mW. Simultaneous pumping of the 2.3 mm Yb:Tm:YLF laser at 685 nm and 960 nm is demonstrated, showing higher slope efficiency than 960 nm alone. Numerical simulations and analytical models show the best ratio of pump power between both wavelengths. (author)
20. Mode-locked Ti:sapphire laser oscillators pumped by wavelength-multiplexed laser diodes
Science.gov (United States)
Sugiyama, Naoto; Tanaka, Hiroki; Kannari, Fumihiko
2018-05-01
We directly pumped a Ti:sapphire laser by combining 478 and 520 nm laser diodes to prevent the effect of absorption loss induced by the pump laser of shorter wavelengths (∼450 nm). We obtain a continuous-wave output power of 660 mW at a total incident pump power of 3.15 W. We demonstrate mode locking using a semiconductor saturable absorber mirror, and 126 fs pulses were obtained at a repetition rate of 192 MHz. At the maximum pump power, the average output power is 315 mW. Shorter mode-locked pulses of 42 and 48 fs were respectively achieved by Kerr-lens mode locking with average output powers of 280 and 360 mW at a repetition rate of 117 MHz.
1. Future directions in 980-nm pump lasers: submarine deployment to low-cost watt-class terrestrial pumps
Science.gov (United States)
Gulgazov, Vadim N.; Jackson, Gordon S.; Lascola, Kevin M.; Major, Jo S.; Parke, Ross; Richard, Tim; Rossin, Victor V.; Zhang, Kai
1999-09-01
The demands of global bandwidth and distribution are rising rapidly as Internet usage grows. This fundamentally means that more photons are flowing within optical cables. While transmitting sources launches some optical power, the majority of the optical power that is present within modern telecommunication systems originates from optical amplifiers. In addition, modern optical amplifiers offer flat optical gain over broad wavelength bands, thus making possible dense wavelength de-multiplexing (DWDM) systems. Optical amplifier performance, and by extension the performance of the laser pumps that drive them, is central to the future growth of both optical transmission and distribution systems. Erbium-doped amplifiers currently dominate optical amplifier usage. These amplifiers absorb pump light at 980 nm and/or 1480 nm, and achieve gain at wavelengths around 1550 nm. 980 nm pumps achieve better noise figures and are therefore used for the amplification of small signals. Due to the quantum defect, 1480 nm lasers deliver more signal photon per incident photon. In addition, 1480 nm lasers are less expensive than 980 nm lasers. Thus, 1480 nm pump lasers are used for amplification in situations where noise is not critical. The combination of these traits leads to the situation where many amplifiers contain 980 nm lasers to pump the input section of the Er- doped fiber with 1480 nm lasers being used to pump the latter section of Er fiber. This can be thought of as using 980 nm lasers to power an optical pre-amplifier with the power amplification function being pump with 1480 nm radiation. This paper will focus on 980 nm pump lasers and the impact that advances in 980 nm pump technology will have on optical amplification systems. Currently, 980 nm technology is rapidly advancing in two areas, power and reliability. Improving reliability is becoming increasingly important as amplifiers move towards employing more pump lasers and using these pump lasers without redundancy
2. The new phases of liquid 3He
International Nuclear Information System (INIS)
Leggett, A.J.
1976-01-01
Comments are made on two new phases of liquid 3 He, referred to as 3 He-A and 3 He-B, discovered in the temperature region below 3 mk. It has been assumed that these new phases are anisotropic superfluids, and a general picture of them is presented, which has been successful in explaining at least qualitatively, many of the static, dynamic and transport properties of the new phases. Whilst the qualitative behaviour is in good agreement with theory there are, however, some quantitative discrepancies. In many cases these may be due to orientational and geometric effects not yet understood. One of the most fruitful areas for comparison of theory and experiment is the NMR behaviour and the dynamic nuclear magnetism. The anomalous behaviour observed arises because the nuclear dipole energy, although very small, can act coherently in the superfluid state. (U.K.)
3. Efficient room temperature cw Yb:glass laser pumped by a 946nm Nd:YAG laser
OpenAIRE
Koch, R.; Clarkson, W.A.; Hanna, D.C.; Jiang, S.; Myers, M.J.; Rhonehouse, D.; Hamlin, S.J.; Griebner, U.; Schönnagel, H.
1997-01-01
By pumping with a cw diode-pumped Nd:YAG laser operating at 946nm laser operation of a new Yb-doped phosphate glass with 440mW cw output power and a slope efficiency of 48% with respect to the absorbed pump power was achieved at room temperature
4. Dye laser with distributed feedback and with pumping by copper-vapor laser
Energy Technology Data Exchange (ETDEWEB)
Mirza, S Yu; Soldatov, A N; Sukhanov, V B
1983-10-01
An experimental study was made for determining the characteristics of dye lasers with distributed feedback, not requiring intricate resonator structures, and the feasibility of their pumping with radiation from a metal-vapor laser. The experiments were performed with five different dyes lasing in the yellow-red (510.6 - 578.2 nm) range of the spectrum: rhodamine 110, 6G, S and ocazine 17,1 in ethyl alcohol solution. The optical equipment included a copper-vapor pumping laser with the gas-discharge tube inside a telescopic resonator of the unstable type. Pumping pulses of 20 ns duration were generated at 510.6 and 578.2 nm wavelengths and a 4 kHz repetition rate. The pumping power was varied by means of an interference filter smoothly adjustable through rotation. The pumping laser beam was focused by a cylindrical lens on the dye cell. At optimum dye concentrations, corresponding to a maximum attainable emission power, dye concentrate was added into the circulation system for determining the dependence of the pumping threshold power on the dye concentration. Also measured were the dependence of the emission efficiency on the pumping power and the tuning range of each dye laser. The efficiency was found to remain constant over the pumping power range from threshold level to eight times higher level. The results reveal different angles of laser beam divergence in the vertical plane and in the horizontal plane, the divergence angle being four times larger in the vertical plane. The conversion efficiency increased, without significant changes in spectral characteristics, with a single annular reflector instead of two reflectors. 9 references, 4 figures, 1 table.
5. Energy dependence of the 3He(3He,π+)6Li reaction
International Nuclear Information System (INIS)
Le Bornec, Y.; Hibou, F.; Bimbot, L.; Hennino, T.; Jourdain, J.C.; Reide, F.; Tatischeff, B.; Willis, N.; Aslanides, E.; Bergdolt, G.; Fassnacht, P.; Racca, C.; Boudard, A.; Bruge, G.; Lugol, J.C.
1983-01-01
The 3 He( 3 He, π + ) 6 Li reaction has been studied as a function of energy using the 3 He beam at SATURNE. Cross sections for the 6 Li ground state (1 + ) and 2.18 MeV (3 + ) levels have been obtained at 350, 420, 500 and 600 MeV incident energies at angles THETAsub(π)(lab)=15 0 and 40 0 . These results are compared with two theoretical predictions. (orig.)
6. Efficient laser-diode end-pumped Nd:GGG lasers at 1054 and 1067 nm.
Science.gov (United States)
Xu, Bin; Xu, Huiying; Cai, Zhiping; Camy, P; Doualan, J L; Moncorgé, R
2014-10-10
Efficient and compact laser-diode end-pumped Nd:GGG simultaneous multiwavelength continuous-wave lasers at ∼1059, ∼1060 and ∼1062 nm were first demonstrated in a free-running 30 mm plano-concave laser cavity. The maximum output power was up to 3.92 W with a slope efficiency of about 53.6% with respect to the absorbed pump power. By inserting a 0.1 mm optical glass plate acting as a Fabry-Pérot etalon, a single-wavelength laser at ∼1067 nm with a maximum output power of 1.95 W and a slope efficiency of 28.5% can be obtained. Multiwavelength lasers, including those at ∼1054 or ∼1067 nm, were also achievable by suitably tilting the glass etalon. These simultaneous multiwavelength lasers provide a potential source for terahertz wave generation.
7. Optically Pumped Far Infrared Molecular Lasers.
Science.gov (United States)
1980-04-01
and 4 were reported by Fetterman , et al. and Gullberg, et al.3 An additional FIR transition (i.e., G:sR(5,4) has been reported,5 but is not shown in...attempt has been made to frequency stabilize the experiment. Recently, Fetterman , et al. 11 performed "real-ti adctral analysis for FIR laser pulses...wave device known 4 as a Reflective Array Compressor (RAC) was developed for just this sort of problem in the radar community. Recently, Fetterman , et al
8. Development of high repetition rate ultra-short pulse solid state lasers pumped by laser diodes
International Nuclear Information System (INIS)
Ueda, Ken-ichi; Lu, Jianren; Takaichi, Kazunori; Yagi, Hideki; Yanagitani, Takakimi; Kaminskii, Alexander; Kawanaka, Junji
2004-01-01
A novel technique for ceramic lasers has been developed recently. Self-energy-driven sintering of nano-and micro particles created the fully transparent Nd:YAG ceramics. The ceramic YAG demonstrated high efficiency operation (optical-to-optical conversion of 60% in end pumping) and solid-phase crystals growth and the possible scaling were investigated principally. Typical performance of ceramic YAG laser has been reviewed. The present status and future prospect of the ceramic lasers technologies were discussed. (author)
9. Optically pumped carbon dioxide laser mixtures. [using solar radiation
Science.gov (United States)
Yesil, O.; Christiansen, W. H.
1979-01-01
This work explores the concept of blackbody radiation pumping of CO2 gas as a step toward utilization of solar radiation as a pumping source for laser action. To demonstrate this concept, an experiment was performed in which laser gas mixtures were exposed to 1500 K thermal radiation for brief periods of time. A gain of 2.8 x 10 to the -3rd reciprocal centimeters has been measured at 10.6 microns in a CO2-He gas mixture of 1 Torr pressure. A simple analytical model is used to describe the rate of change of energy of the vibrational modes of CO2 and to predict the gain. Agreement between the prediction and experiment is good.
10. High-current electron accelerator for gas-laser pumping
Energy Technology Data Exchange (ETDEWEB)
Badaliants, G R; Mamikonian, V A; Nersisian, G Ts; Papanian, V O
1978-11-26
A high-current source of pulsed electron beams has been developed for the pumping of UV gas lasers. The parameters of the device are: energy of 0.3-0.7 MeV pulse duration of 30 ns and current density (in a high-pressure laser chamber) of 40-100 A/sq cm. The principal feature of the device is the use of a rectangular cold cathode with incomplete discharge along the surface of the high-permittivity dielectric. Cathodes made of stainless steel, copper, and graphite were investigated.
11. Multi-photon microscope driven by novel green laser pump
Science.gov (United States)
Marti, Dominik; Djurhuus, Martin; Jensen, Ole Bjarlin; Andersen, Peter E.
2016-03-01
Multi-photon microscopy is extensively used in research due to its superior possibilities when compared to other microscopy modalities. The technique also has the possibility to advance diagnostics in clinical applications, due to its capabilities complementing existing technology in a multimodal system. However, translation is hindered due to the high cost, high training demand and large footprint of a standard setup. We show in this article that minification of the setup, while also reducing cost and complexity, is indeed possible without compromising on image quality, by using a novel diode laser replacing the commonly used conventional solid state laser as the pump for the femtosecond system driving the imaging.
12. Diode-pumped two micron solid-state lasers
International Nuclear Information System (INIS)
Elder, I.F.
1997-01-01
This thesis presents an investigation of diode-pumped two micron solid-state lasers, concentrating on a comparison of the cw room temperature operation of Tm:YAP, Tm,Ho:YAP and Tm,Ho:YLF. Dopant concentrations in YAP were 4.2% thulium and 0.28% holmium; in YLF they were 6% thulium and 0.4% holmium. Thermal modelling was carried out in order to provide an insight into the thermal lensing and population distributions in these materials. Laser operation was achieved utilising an end-pumping geometry with a simple two mirror standing wave resonator. The pump source for these experiments was a 3 W laser diode. Maximum output power was achieved with Tm:YAP, generating 730 mW of laser output, representing 42% conversion efficiency in terms of absorbed pump power. Upper bounds on the conversion efficiency of Tm,Ho:YAP and Tm,Ho:YLF laser crystal of 14% and 30% were obtained, with corresponding output powers of 270 and 660 mW. In all three cases, the output beam was TEM 00 in nature. Visible upconversion fluorescence bands in the green and red were identified in Tm,Ho:YAP and Tm,Ho:YLF, with additional blue emission from the latter, all assigned to transitions on holmium. The principal upconversion mechanisms in these materials all involved the holmium first excited state. Upconversion in Tm:YAP was negligible. The spectral output of Tm:YAP consisted of a comb of lines in the range 1.965 to 2.020 μm. For both the double-doped crystals, the laser output was multilongitudinal mode on a single transition, wavelength 2.120 μm in YAP, 2.065 μm in YLF. In the time domain the output of Tm:YAP was dominated by large amplitude spiking, unlike both of the double-doped laser crystals. The long lifetime of the thulium upper laser level (4.4 ms) provided very weak damping of the spiking. Excitation sharing between thulium and holmium, with a measured characteristic lifetime in YAP of 11.9 μs and YLF of 14.8 μs, provided strong damping of any spiking behaviour. (author)
13. Gradient heating protocol for a diode-pumped alkali laser
Science.gov (United States)
Cai, He; Wang, You; Han, Juhong; Yu, Hang; Rong, Kepeng; Wang, Shunyan; An, Guofei; Wang, Hongyuan; Zhang, Wei; Wu, Peng; Yu, Qiang
2018-06-01
A diode-pumped alkali laser (DPAL) has gained rapid development in the recent years. Until now, the structure with single heater has been widely utilized to adjust the temperature of an alkali vapor cell in most of the literatures about DPALs. However, for an end-pumped DPAL using single heater, most pump energy is absorbed by the gain media near the entrance cell window because of the large absorption cross section of atomic alkali. As a result, the temperature in the pumping area around the entrance window will go up rapidly, especially in a case of high pumping density. The temperature rise would bring about some negative influences such as thermal effects and variations in population density. In addition, light scattering and window contamination aroused by the chemical reaction between the alkali vapor and the buffer gas will also affect the output performance of a DPAL system. To find a solution to these problems, we propose a gradient heating approach in which several heaters are tandem-set along the optical axis to anneal an alkali vapor cell. The temperature at the entrance window is adjusted to be lower than that of the other side. By using this novel scheme, one can not only achieve a homogeneous absorption of the pump energy along the cell axis, but also decrease the possibility of the window damage in a DPAL configuration. The theoretical simulation of the laser output features has been carried out for a configuration of multiple heaters. Additionally, the DPAL output performance under different gradient temperatures is also discussed in this paper. The conclusions might be helpful for development of a high-powered and high-beam-quality DPAL.
14. Small objects in superfluid 3He
International Nuclear Information System (INIS)
Rainer, D.; Vuorio, M.
1977-02-01
Distortions in the superfluid order parameter around a small object in 3 He are calculated together with the supercurrents and the angular momentum induced by it in the liquid. The forces acting on the impurity by the liquid texture structure are also considered. (author)
15. 3He neutral current detectors at SNO
International Nuclear Information System (INIS)
Elliott, S.R.; Browne, M.C.; Doe, P.J.
1998-01-01
The flux of solar neutrinos measured via charged and neutral current interactions can provide a model independent test of neutrino oscillations. Since the Sudbury Neutrino Observatory uses heavy water as a target, it has a large sensitivity to both interactions. A technique for observing the neutral current breakup of the deuteron using 3 He proportional counters is described
16. Multipole pair vibrations in superfluid 3He
International Nuclear Information System (INIS)
Baldo, M.; Giansiracusa, G.; Lombardo, U.; Pucci, R.; Petronio, G.
1978-01-01
Starting from a path integral formation of the 3 He superfluidity, the authors study the pair vibrations around the BCS solution. For both the BW and ABM states get a set of possible excitations. In particular it is shown that a new type of excitation is present for pure 1 = 2 spin singlet vibration. (Auth.)
17. Separable interactions and liquid 3He
International Nuclear Information System (INIS)
Nijhoff, F.W.
1984-01-01
In this thesis, the different phases of liquid 3 He are studied in the presence and absence of magnetic field. It offers microscopic calculations starting from BCS hamiltonians with some additional terms (Zeeman-term to include the magnetic field; an Hubbard-term to include spin fluctuations). A systematic determination of the phase diagram is presented. (Auth.)
18. Electric dipole moment of 3He
International Nuclear Information System (INIS)
Avishai, Y.; Fabre de la Ripelle, M.
1987-01-01
The contribution of CP violating nucleon-nucleon interaction to the electric dipole moment of 3 He is evaluated following a recent proposal for its experimental detection. Two models of CP violating interactions are used, namely, the Kobayashi-Maskawa mechanism and the occurrence of the Θ term in the QCD lagrangian. These CP violating interactions are combined with realistic strong nucleon-nucleon interactions to induce a CP forbidden component of the 3 He wave function. The matrix element of the electric dipole operator is then evaluated between CP allowed and CP forbidden components yielding the observable electric dipole moment. Using the parameters emerging from the penguin terms in the Kobaysashi-Maskawa model we obtain a result much larger than the electric dipole moment of the neutron in the same model. On the other hand, no enhancement is found for the Θ-term mechanism. A possible explanation for this difference is discussed. Numerical estimates can be given only in the Kobayashi-Maskawa model, giving d( 3 He) ≅ 10 30 e . cm. In the second mechanism, the estimate give d ( 3 He) ≅ 10 16 anti Θ. (orig.)
19. Method and system for homogenizing diode laser pump arrays
Science.gov (United States)
Bayramian, Andy J
2013-10-01
An optical amplifier system includes a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars. The periodic distance is measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars. The diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%. The optical amplifier system also includes a diffractive optic disposed along the optical path. The diffractive optic includes a photo-thermo-refractive glass member. The optical amplifier system further includes an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance. A second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%.
20. LED-pumped Alexandrite laser oscillator and amplifier
Science.gov (United States)
Pichon, Pierre; Blanchot, Jean-Philippe; Balembois, François; Druon, Frédéric; Georges, Patrick
2018-02-01
In this paper, we report the first LED-pumped transition-metal-doped laser oscillator and amplifier based on an alexandrite crystal (Cr3+:BeAl2O4). A Ce:YAG luminescent concentrator illuminated by blue LEDs is used to reach higher pump powers than with LEDs alone. The luminescent 200-mm-long-composit luminescent concentrator involving 2240 LEDs can delivers up to 268 mJ for a peak irradiance of 8.5 kW/cm2. In oscillator configuration, an LED-pumped alexandrite laser delivering an energy of 2.9 mJ at 748 nm in free running operation is demonstrated. In the cavity, we measured a double pass small signal gain of 1.28, in good agreement with numerical simulations. As amplifier, the system demonstrated to boost a CW Ti:sapphire laser by a factor of 4 at 750 nm in 8 passes with a large tuning range from 710 nm to 800 nm.
1. Efficient high power operation of erbium 3 µm fibre laser diode-pumped at 975 nm
NARCIS (Netherlands)
Jackson, S.D.; King, T.A.; Pollnau, Markus
2000-01-01
Efficient CW operation of a 2.71 um Er,Pr:ZBLAN double-clad fibre laser pumped with a single diode laser operating at a wavelength of 975 nm is described. A maximum output power of 0.5 W and a slope efficiency of 25% (with respect to the launched pump power) were obtained. Threshold pump powers of <
2. π--induced single charge exchange on polarized 3He
International Nuclear Information System (INIS)
Zhao, Q.; Burleson, S.; Blanchard, T.
1995-01-01
Asymmetries, A y , for the (π - ,π 0 ) reaction on polarized 3 He were measured using the pion beam of the P3W channel at LAMPF. The π 0 were detected with the new Neutral Meson Spectrometer (NMS) in coincidence with recoiling tritons. The recoil detector consisted of scintillation-counter telescopes and a wire chamber that provided energy-loss and direction information, respectively. The polarized gaseous 3 He target developed at TRIUMF was modified and run with the use of two diode lasers. Polarizations were typically 50%. The A y taken at T π = 200 MeV between 60 and 105 degrees were found to be strongly angle-dependent. The results will be compared with the theoretical predictions
3. Specific heat of amorphous 3He films and confined liquid 3He
International Nuclear Information System (INIS)
Golov, A.; Pobell, F.
1995-01-01
We have measured the heat capacities of 3 He films and liquid 3 He in porous Vycor glass at 10 to 600 mK. With increasing the film thickness front 1 to 3 atomic layers , the specific heat evolves gradually from that typical to solid to that of liquid 3 He. At about 2 atomic layers, however, its low-temperature part is nearly temperature-independent; we interpret this as a result of gradual freezing of spins in an amorphous solid 3 He film with decreasing the temperature. The contribution of liquid 3 He in the center of the Vycor pores can be described as the specific heat of bulk liquid 3 He at corresponding pressures in the range 0 to 28 bar. The thickness of amorphous solid on the pore walls increases with external pressure roughly linearly. Preplating the walls with 4 He allows to determine the positions of 3 He atoms contributing to the surface specific heat at 10 to 50 mK. In addition, the contribution from the specific heat of 3 He- 4 He mixing at 100 to 600 mK is discussed as a function of pressure and amount of 4 He
4. Design windows of laser fusion power plants and conceptual design of laser-diode pumped slab laser
International Nuclear Information System (INIS)
Kozaki, Y.; Eguchi, T.; Izawa, Y.
1999-01-01
An analysis of the design space available to laser fusion power plants has been carried out, in terms of design key parameters such as target gain, laser energy and laser repetition rate, the number of fusion react ion chambers, and plant size. The design windows of economically attractive laser fusion plants is identified with the constraints of key design parameters and the cost conditions. Especially, for achieving high repetition rate lasers, we have proposed and designed a diode-pumped solid-state laser driver which consists of water-cooled zig-zag path slab amplifiers. (author)
5. Galactic evolution of D and 3He including stellar production of 3He
International Nuclear Information System (INIS)
Dearborn, D.S.; Steigman, G.; Tosi, M.
1996-01-01
New stellar models which track the production and destruction of 3 He (and D) have been evolved for a range of stellar masses (0.65≤M/M circle-dot ≤100), metallicities (0.01≤Z/Z circle-dot ≤1), and initial (main-sequence) 3 He mass fractions (10 -5 ≤X 3,MS ≤10 -3 ). Armed with the 3 He yields from these stellar models we have followed the evolution of D and 3 He using a variety of chemical evolution models with and without infall of primordial or processed material. Production of new 3 He by the lower mass stars overwhelms any reasonable primordial contributions and leads to predicted abundances in the presolar nebula and/or the present interstellar medium in excess of the observationally inferred values. This result, which obtains even for zero primordial D and 3 He, and was anticipated by Rood, Steigman, ampersand Tinsley is insensitive to the choice of chemical evolution model; it is driven by the large 3 He yields from low-mass stars. In an attempt to ameliorate this problem we have considered a number of nonstandard models in which the yields from low-mass stars have been modified. Although several of these nonstandard models may be consistent with the 3 He data, they may be inconsistent with observations of 12 C/ 13 C, 18 O, and, most seriously the super- 3 He rich planetary nebulae. Even using the most extreme of these nonstandard models we obtain a generous upper bound to pregalactic 3 He:X 3P ≤3.2x10 -5 which, nonetheless, leads to a stringent lower bound to the universal density of nucleons. copyright 1996 The American Astronomical Society
6. Ultrafast laser pump/x-ray probe experiments
International Nuclear Information System (INIS)
Larsson, J.; Judd, E.; Schuck, P.J.
1997-01-01
In an ongoing project aimed at probing solids using x-rays obtained at the ALS synchrotron with a sub-picosecond time resolution following interactions with a 100 fs laser pulse, the authors have successfully performed pump-probe experiments limited by the temporal duration of ALS-pulse. They observe a drop in the diffraction efficiency following laser heating. They can attribute this to a disordering of the crystal. Studies with higher temporal resolution are required to determine the mechanism. The authors have also incorporated a low-jitter streakcamera as a diagnostic for observing time-dependant x-ray diffraction. The streakcamera triggered by a photoconductive switch was operated at kHz repetition rates. Using UV-pulses, the authors obtain a temporal response of 2 ps when averaging 5000 laser pulses. They demonstrate the ability to detect monochromatized x-ray radiation from a bend-magnet with the streak camera by measuring the pulse duration of a x-ray pulse to 70 ps. In conclusion, the authors show a rapid disordering of an InSb crystal. The resolution was determined by the duration of the ALS pulse. They also demonstrate that they can detect x-ray radiation from a synchrotron source with a temporal resolution of 2ps, by using an ultrafast x-ray streak camera. Their set-up will allow them to pursue laser pump/x-ray probe experiments to monitor structural changes in materials with ultrafast time resolution
7. The obtaining of giant laser pulses by optical pumping
International Nuclear Information System (INIS)
Briquet, Georges
1970-12-01
From coherent pumping studies a laser of short pulse duration was developed. Further study of laser effects in organic substances was envisaged. The first part of the work yielded awaited results, and led to the development of a single mode emitter (due to the small dimensions of the cavity). The principles of laser action were enumerated and the relative parameters defined. Various methods of obtaining pulses were discussed; the reasons behind the particular choice mode were given. A theoretical study was then made leading to the establishment of the fundamental equations defining the pulse formation process. An important part of the test deals with technical implications and the experimental results, which have arisen. The conclusion reviews possible applications. (author) [fr
8. High-power pulsed and CW diode-pumped mode-locked Nd:YAG lasers
Science.gov (United States)
Marshall, Larry R.; Hays, A. D.; Kaz, Alex; Kasinski, Jeff; Burnham, R. L.
1991-01-01
The operation of both pulsed and CW diode-pumped mode-locked Nd:YAG lasers are presented. The pulsed laser produced 1.0 mJ with pulsewidths of 90 psec at 20 Hz. The CW pumped laser produced 6 W output at 1.064 microns and 3 W output at 532 nm.
9. Vacuum ultraviolet Ar2*laser pumped by a high-intensity laser
International Nuclear Information System (INIS)
Kubodera, Shoichi; Kaku, Masanori; Higashiguchi, Takeshi
2004-01-01
We observed a small-signal gain of Ar 2 * emission at 126 nm by use of an Ar-filled hollow fiber to guide the ultrashort-pulse high-intensity laser propagation. The small signal gain coefficient was measured to be 0.05 cm -1 at 126 nm. Kinetic analysis revealed that the electrons produced by the high-intensity laser through an optical-field ionization process initiated the Ar 2 * production process. This laser scheme could be combined with high harmonic radiation of the pump laser in the vacuum ultraviolet (VUV), leading to the production of amplified ultrashort VUV pulses. (author)
10. Development of laser diode-pumped high average power solid-state laser for the pumping of Ti:sapphire CPA system
Energy Technology Data Exchange (ETDEWEB)
Maruyama, Yoichiro; Tei, Kazuyoku; Kato, Masaaki; Niwa, Yoshito; Harayama, Sayaka; Oba, Masaki; Matoba, Tohru; Arisawa, Takashi; Takuma, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1998-03-01
Laser diode pumped all solid state, high repetition frequency (PRF) and high energy Nd:YAG laser using zigzag slab crystals has been developed for the pumping source of Ti:sapphire CPA system. The pumping laser installs two main amplifiers which compose ring type amplifier configuration. The maximum amplification gain of the amplifier system is 140 and the condition of saturated amplification is achieved with this high gain. The average power of fundamental laser radiation is 250 W at the PRF of 200 Hz and the pulse duration is around 20 ns. The average power of second harmonic is 105 W at the PRF of 170 Hz and the pulse duration is about 16 ns. The beam profile of the second harmonic is near top hat and will be suitable for the pumping of Ti:sapphire laser crystal. The wall plug efficiency of the laser is 2.0 %. (author)
11. Red laser-diode pumped 806 nm Tm3+: ZBLAN fibre laser
Science.gov (United States)
Juárez-Hernández, M.; Mejía, E. B.
2017-06-01
A Tm3+-doped fluorozirconate (ZBLAN) fibre laser operating CW at 806 nm when diode-pumped at 687 nm is described for the first time. This device is based on the 3F4 → 3H6 transition, and is suitable for first telecom window and sensing applications. A slope efficiency of 50.3% and low threshold pump-power of 11.6 mW were obtained. Maximum output power of 15 mW for 40 mW coupled pump was achieved.
12. High temperature semiconductor diode laser pumps for high energy laser applications
Science.gov (United States)
Campbell, Jenna; Semenic, Tadej; Guinn, Keith; Leisher, Paul O.; Bhunia, Avijit; Mashanovitch, Milan; Renner, Daniel
2018-02-01
Existing thermal management technologies for diode laser pumps place a significant load on the size, weight and power consumption of High Power Solid State and Fiber Laser systems, thus making current laser systems very large, heavy, and inefficient in many important practical applications. To mitigate this thermal management burden, it is desirable for diode pumps to operate efficiently at high heat sink temperatures. In this work, we have developed a scalable cooling architecture, based on jet-impingement technology with industrial coolant, for efficient cooling of diode laser bars. We have demonstrated 60% electrical-to-optical efficiency from a 9xx nm two-bar laser stack operating with propylene-glycolwater coolant, at 50 °C coolant temperature. To our knowledge, this is the highest efficiency achieved from a diode stack using 50 °C industrial fluid coolant. The output power is greater than 100 W per bar. Stacks with additional laser bars are currently in development, as this cooler architecture is scalable to a 1 kW system. This work will enable compact and robust fiber-coupled diode pump modules for high energy laser applications.
13. Vibrational relaxation induced population inversions in laser pumped polyatomic molecules
International Nuclear Information System (INIS)
Shamah, I.; Flynn, G.; Columbia Univ., New York
1981-01-01
Conditions for population inversion in laser pumped polyatomic molecules are described. For systems which exhibit metastable vibrational population distributions, large, long lived inversions are possible even when the vibrational modes are strongly coupled by rapid collisional vibration-vibration (V-V) energy transfer. Overtone states of a hot mode are found to invert with respect to fundamental levels of a cold mode even at V-V steady state. Inversion persists for a V-T/R relaxation time. A gain of 4 m -1 for the 2ν 3 → ν 2 transition in CH 3 F (lambda approx. 15.9 μ) was found assuming a spontaneous emission lifetime of 10 s for this transition. General equations are derived which can be used to determine the magnitude of population inversion in any laser pumped, vibrationally metastable, polyatomic molecule. A discussion of factors controlling the population maxima of different vibrational states in optically pumped, V-V equilibrated metastable polyatomics is also given. (orig./WL)
14. Test of sup 3 He-based neutron polarizers at NIST
CERN Document Server
Jones, G L; Thompson, A K; Chowdhuri, Z; Dewey, M S; Snow, W M; Wietfeldt, F E
2000-01-01
Neutron spin filters based on polarized sup 3 He are useful over a wide neutron energy range and have a large angular acceptance among other advantages. Two optical pumping methods, spin-exchange and metastability-exchange, can produce the volume of highly polarized sup 3 He gas required for such neutron spin filters. We report a test of polarizers based on each of these two methods on a new cold, monochromatic neutron beam line at the NIST Center for Neutron Research.
15. Diode-pumped continuous-wave eye-safe Nd:YAG laser at 1415 nm.
Science.gov (United States)
Lee, Hee Chul; Byeon, Sung Ug; Lukashev, Alexei
2012-04-01
We describe the output performance of the 1415 nm emission in Nd:YAG in a plane-concave cavity under traditional pumping into the 4F5/2 level (808 nm) and direct in-band pumping into the 4F3/2 level (885 nm). An end-pumped Nd:YAG laser yielded maximum cw output power of 6.3 W and 4.2 W at 885 nm and 808 nm laser diode (LD) pumping, respectively. To the best of our knowledge, this is the highest output power of a LD-pumped 1415 nm laser.
16. Solar-pumped fiber laser with transverse-excitation geometry
Science.gov (United States)
Masuda, Taizo; Iyoda, Mitsuhiro; Yasumatu, Yuta; Yamashita, Tomohiro; Sasaki, Kiyoto; Endo, Masamori
2018-02-01
In this paper, we demonstrate an extremely low-concentrated solar-pumped laser (SPL) that uses a transversely excited fiber laser geometry. To eliminate the need for precise solar tracking with an aggressive cooling system and to considerably increase the number of laser applications, low-concentration factors in SPLs are highly desired. We investigate the intrinsic low-loss property of SiO2 optical fibers; this property can be used to compensate for the extremely low gain coefficient of the weakly-pumped active medium by sunlight. As part of the experimental setup, a 40-m long Nd3+-doped SiO2 fiber coil was packed in a ring-shaped chamber filled with a sensitizer solution; this solution functioned as a down-shifter. The dichroic top window of the chamber transmitted a wide range of sunlight and reflected the down-shifted photons, confining them to the highly-reflective chamber until they were absorbed by the Nd3+ ions in the active fiber. We demonstrated a lasing threshold that is 10 times the concentration of natural sunlight and two orders of magnitude smaller than that of conventional SPLs.
17. Single-mode Brillouin fiber laser passively stabilized at resonance frequency with self-injection locked pump laser
International Nuclear Information System (INIS)
2012-01-01
We demonstrate a single-mode Brillouin fiber ring laser, which is passively stabilized at pump resonance frequency by using self-injection locking of semiconductor pump laser. Resonance condition for Stokes radiation is achieved by length fitting of Brillouin laser cavity. The laser generate single-frequency Stokes wave with linewidth less than 0.5 kHz using approximately 17-m length cavity
18. The cross section of 3He(3He,2p)4He measured at solar energies
International Nuclear Information System (INIS)
Junker, M.; Arpesella, C.; Bellotti, E.; Broggini, C.; Corvisiero, P.; D'Alessandro, A.; Fiorentini, G.; Fubini, A.; Gervino, G.; Greife, U.; Gustavino, C.; Lambert, J.; Prati, P.; Rodney, W.S.; Rolfs, C.; Trautvetter, H.P.; Zavatarelli, S.
1999-01-01
We report on the status of the 3 He( 3 He,2p) 4 He experiment at the underground accelerator facility LUNA (Gran Sasso). The lowest projectile energies for the measured cross section correspond already to energies below the center of the solar Gamow peak (E 0 =22 keV). The data provide no evidence for the existence of a hypothetical resonance in the energy range investigated. Although no extrapolation is needed anymore (except for energies at the low-energy tail of the Gamow peak), the data must be corrected for the effects of electron screening, clearly observed the first time for the 3 He( 3 He,2p) 4 He reaction. The effects are however larger than expected and not understood, leading presently to the largest uncertainty on the quoted S(0) value for bare nuclides (= 5.40 MeVb)
19. NMR and superfluidity of 3He in 3He-4He solutions
International Nuclear Information System (INIS)
Ivanova, K.D.; Mejerovich, A.Eh.
1986-01-01
Two possibilities of determining the superfluid transition temperature for 3 He in a 3 He- 4 He solution by the NMR technique are discussed. One of the methods consists in measuring the spin diffusion coefficient in weak magnetic fields at ultralow temperatures, and the other in measuring the ratio of the spin diffusion coefficient to the spin wave absorption coefficient at not very low temperatures. The transition temperature is estimated on the basis of the available experimental data. The effect of the superfluid transition in a system of 3 He quasiparticles on the propagation of transverse spin waves and longitudinal spin-sound oscillations in 3 He- 4 He solutions is studied. It is shown that there is a range of weak magnetic field intensities restricted from both sides in which the propagation of weakly damped spin-sound waves is possible
20. The search for high-energy deuterons in the 3He +3He reaction
International Nuclear Information System (INIS)
Pigeon, R.; Slobodrian, R.J.
1979-01-01
High-energy deuterons have been detected from the 3 He + 3 He reaction with a system sensitive to cross-sections of 0.6 nb sr -1 . Several tests have permitted to evaluate the small contribution of spurious events. The deuterons are kenematically consistent with the reaction 3 He + 3 He→ 2 H + 4 He + e + +ν, but the measured cross-section at 20deg laboratory is too high for a weak-interaction process; (1.3 +- 0.2) nb sr -1 . It might be due to an interaction of intermediate strength causing the decay of pp pairs ( 3 He) into deuterons. Other alternatives and the implications concerning fusion processes and the production of neutrinos in the sun are discussed in the text
1. Coupling between Solid 3He on Aerogel and Superfluid 3He in the Low Temperature Limit
International Nuclear Information System (INIS)
Bradley, D. I.; Fisher, S. N.; Guenault, A. M.; Haley, R. P.; Pickett, G. R.; Tsepelin, V.; Whitehead, R. C. V.; Skyba, P.
2006-01-01
We have cooled liquid 3He contained in a 98% open aerogel sample surrounded by bulk superfluid 3He-B at zero pressure to below 120 μK. The aerogel sample is placed in a quasiparticle blackbody radiator cooled by a Lancaster-style nuclear cooling stage to ∼200 μK. We monitor the temperature of the 3He inside the blackbody radiator using a vibrating wire resonator. We find that reducing the magnetic field on the aerogel sample causes substantial cooling of all the superfluid inside the blackbody radiator. We believe this is due to the demagnetization of the solid 3He layers on the aerogel strands. This system has potential for achieving extremely low temperatures in the confined fluid
2. Tunable, diode side-pumped Er:YAG laser
Science.gov (United States)
Hamilton, C.E.; Furu, L.H.
1997-04-22
A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 {micro}m, and is tunable over a 6 nm range near about 2.936 {micro}m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 {micro}m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 {micro}m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems. 4 figs.
3. Diode-Pumped Thulium (Tm)/Holmium (Ho) Composite Fiber 2.1-Micrometers Laser
Science.gov (United States)
2015-09-01
Schematic of the 800-nm diode pumped Tm/Ho composite fiber laser 8 Under quasi-continuous wave (Q- CW ) pumping conditions of 1-ms duration and a...Fig. 9 (Top) Schematic of the 800-nm diode -pumped Tm/Ho composite fiber laser with outcoupler. (Left) Q- CW laser performance of the Tm/Ho composite...ARL-TR-7452 ● SEP 2015 US Army Research Laboratory Diode -Pumped Thulium (Tm)/Holmium (Ho) Composite Fiber 2.1-μm Laser by G
4. 12C(3He,3He n)11C cross section at 910 MeV
International Nuclear Information System (INIS)
Aslanides, E.; Fassnacht, P.; Dellacasa, G.; Gallio, M.; Tuyn, J.W.N.
1981-01-01
The 12 C( 3 He, 3 He n) 11 C cross section at 910 MeV was measured by using a Ge(Li) gamma spectrometer to determine the disintegration rate and measuring the incident flux by means of a scintillator telescope. Cross sections for the production of 7 Be in C and Al and for the production of 24 Na in Al are then determined using the measured cross section as a monitor
5. Development of laser diode pumped Nd:glass slab laser driver for the inertial fusion energy
International Nuclear Information System (INIS)
Yamanaka, Masanobu; Kanabe, Tadashi; Yasuhara, Ryo
2002-01-01
A diode-pumped solid state laser (DPSSL) is promising candidate of reactor driver for Inertial Fusion Energy (IFE). As a first step of a driver development for the IFE, we are developing a laser diode pumped zig-zag Nd:glass slab laser amplifier system HALNA 10 (High Average-power Laser for Nuclear-fusion Application) which can generated an output of 10 J per pulse at 1053 nm in 10 Hz operation. The water-cooled zig zag Nd:glass slab is pumped from both sides by 803 nm AIGaAs laser diode (LD) module, each LD module has an emitting area of 420 mm x 10 mm and two LD modules generate in total 218 (max.) kW peak power with 2.6 kW/cm 2 peak intensity at 10 Hz repetition rate. We have obtained in first-stage experiment 8.5 J output energy at 0.5 Hz with a beam quality of 2 times diffraction limited far-field pattern, which nearly confirmed our conceptual design. Since the key issue for the IFE DPSSL drive module were almost satisfactory, we have a confidence that a next 100 J x 10 Hz DPSSL module (HALNA 100) can be constructed. Thermal effects in laser slab, Faraday rotator, Faraday isolator and Pockets cell and their managements are discussed.
6. Excitonic bistabilities, instabilities and chaos in laser-pumped semiconductor
International Nuclear Information System (INIS)
Nguyen Ba An; Nguyen Trung Dan; Hoang Xuan Nguyen
1992-07-01
The Hurwitz criteria are used for a stability analysis of the steady state excitonic optical bistability curves in a semiconductor pumped by an external laser resonant with the exciton level. Besides the middle branch of the bistability curves which is unstable in the sense of the linear stability theory, we have found other domains of instability in the upper and lower branches of the steady state curves. Numerical results show that a possible route to chaos in the photon-exciton system is period-doubling self-oscillation process. The influence of the presence of free carriers that coexist with the excitons is also discussed. (author). 16 refs, 6 figs
7. Runaway electron beam control for longitudinally pumped metal vapor lasers
Science.gov (United States)
Kolbychev, G. V.; Kolbycheva, P. D.
1995-08-01
Physics and techniques for producing of the pulsed runaway electron beams are considered. The main obstacle for increasing electron energies in the beams is revealed to be a self- breakdown of the e-gun's gas-filled diode. Two methods to suppress the self-breakdown and enhance the volumetric discharge producing the e-beam are offered and examined. Each of them provides 1.5 fold increase of the ceiling potential on the gun. The methods also give the ways to control several guns simultaneously. Resulting in the possibility of realizing the powerful longitudinal pumping of metal-vapor lasers on self-terminated transitions of atoms or ions.
8. Realization of a broad band neutron spin filter with compressed, polarized 3He gas
International Nuclear Information System (INIS)
Surkau, R.; Otten, E.W.; Steiner, M.; Tasset, F.; Trautmann, N.
1997-01-01
The strongly spin dependent absorption of neutrons in nuclear spin polarized 3 -2pt vector He opens the possibility to polarize beams of thermal and epithermal neutrons. An effective 3 He neutron spin filter (NSF) requires high 3 He nuclear polarization as well as a filter thickness corresponding to a gas amount of the order of 1 bar l. We realized such a filter using direct optical pumping of metastable 3 He * atoms in a 3 He plasma at 1 mbar. Metastable exchange scattering transfers the angular momentum to the whole ensemble of 3 He atoms. At present 3 x 10 18 3 He-atoms/s are polarized up to 64%. Subsequent polarization preserving compression by a two stage compressor system enables to prepare NSF cells of about 300 cm 3 volume with 3 bar of polarized 3 He within 2 h. 3 He polarizations up to 53% were measured in a cell with a filter length of about 15 cm. By this cell a thermal neutron beam from the Mainz TRIGA reactor was polarized. A wavelength selective polarization analysis by means of Bragg scattering revealed a neutron polarization of 84% at a total transmission of 12% for a neutron wavelength of 1 A. (orig.)
9. Free energy of superfluid 3He
International Nuclear Information System (INIS)
Rainer, D.; Serene, J.W.
1976-01-01
A systematic scheme is presented for calculating the free energy of superfluid Fermi liquids by an asymptotic expansion in the small parameter T/subc//T/subF/. This scheme is used to evaluate the strong-coupling corrections to the free energy of superfluid 3 He. It is shown that the leading corrections can be expressed in terms of the normal-state quasiparticle scattering amplitude, and the strong-coupling results are discussed using the s-p approximation for the scattering amplitude
10. Pion absorption in flight on 3He
International Nuclear Information System (INIS)
Ljungfelt, S.H.
1985-02-01
Pion absorption in flight on 3 He has been measured in a kinematically complete manner. The experiment was done in the πE1-channel at the Swiss Institute for Nuclear Research, SIN, using π + - and π - -beams of 120 and 165 MeV kinetic energy. Two of the emitted particles were measured in coincidence and identified by their time-of-flight/pulseheight relation. The obtained two-dimensional energy representation enabled a separation of the different kinematical regions and exhibited a clear enhancement in the region of quasifree absorption, QFA. (orig./WL)
11. Electric dipole moment of 3He
International Nuclear Information System (INIS)
Avishai, Y.; Fabre de la Ripelle, M.
1986-01-01
The contribution of a CP-nonconserving nucleon-nucleon interaction to the electric dipole moment of 3 He is evaluated in view of a recent proposal for its experimental detection. We use two models of CP-nonconserving interactions in combination with a Reid soft-core strong nucleon-nucleon interaction. In the Kobayashi-Maskawa model of CP nonconservation the order of magnitude is 10 -30 eX while the presence of the theta term in the QCD Langrangian contributes an order of magnitude 10 -16 theta-bar e cm
12. Feasibility study of a sup 3 He-magnetometer for neutron electric dipole moment experiments
CERN Document Server
Borisov, Y; Leduc, M; Lobashev, V; Otten, E W; Sobolev, Y
2000-01-01
We report on a sup 3 He-magnetometer capable of detecting tiny magnetic field fluctuations of less than 10 sup - sup 1 sup 4 T in experiments for measuring the electric dipole moment (EDM) of the neutron. It is based on the Ramsey technique of separated oscillating fields and uses nuclear spin-polarized sup 3 He gas which is stored in two vessels of V approx =10 l in a sandwich-type arrangement around the storage bottle for ultra-cold neutrons (UCN). The gas is polarized by means of optical pumping in a separate, small discharge cell at pressures around 0.5 mbar and is then expanded into the actual magnetometer volume. To detect the polarization of sup 3 He gas at the end of the storage cycle the gas is pumped out by means of an oil-diffusion pump and compressed again into the discharge cell where optical detection of nuclear polarization is used.
13. High-power fiber-coupled pump lasers for fiber lasers
Science.gov (United States)
Kasai, Yohei; Aizawa, Takuya; Tanaka, Daiichiro
2018-02-01
We present high-power fiber-coupled pump modules utilized effectively for ultra-high power single-mode (SM) fiber lasers. Maximum output power of 392 W was achieved at 23 A for 915 nm pump, and 394 W for 976 nm pump. Fiber core diameter is 118 μm and case temperature is 25deg. C. Polarization multiplexing technique was newly applied to our optical system. High-reliability of the laser diodes (LD) at high-power operation has been demonstrated by aging tests. Advanced package structure was developed that manages uncoupled light around input end of the fiber. 800 hours continuous drive with uncoupled light power of 100 W has been achieved.
14. Solar-pumped electronic-to-vibrational energy transfer lasers
Science.gov (United States)
Harries, W. L.; Wilson, J. W.
1981-01-01
The possibility of using solar-pumped lasers as solar energy converters is examined. The absorbing media considered are halogens or halogen compounds, which are dissociated to yield excited atoms, which then hand over energy to a molecular lasing medium. Estimates of the temperature effects for a Br2-CO2-He system with He as the cooling gas are given. High temperatures can cause the lower energy levels of the CO2 laser transition to be filled. The inverted populations are calculated and lasing should be possible. However, the efficiency is less than 0.001. Examination of other halogen-molecular lasant combinations (where the rate coefficients are known) indicate efficiencies in all cases of less than 0.005.
15. Nuclear-pumped lasers for large-scale applications
International Nuclear Information System (INIS)
Anderson, R.E.; Leonard, E.M.; Shea, R.F.; Berggren, R.R.
1989-05-01
Efficient initiation of large-volume chemical lasers may be achieved by neutron induced reactions which produce charged particles in the final state. When a burst mode nuclear reactor is used as the neutron source, both a sufficiently intense neutron flux and a sufficiently short initiation pulse may be possible. Proof-of-principle experiments are planned to demonstrate lasing in a direct nuclear-pumped large-volume system; to study the effects of various neutron absorbing materials on laser performance; to study the effects of long initiation pulse lengths; to demonstrate the performance of large-scale optics and the beam quality that may be obtained; and to assess the performance of alternative designs of burst systems that increase the neutron output and burst repetition rate. 21 refs., 8 figs., 5 tabs
16. Improving Lifetime of Quasi-CW Laser Diode Arrays for Pumping 2-Micron Solid State Lasers
Science.gov (United States)
Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.
2007-01-01
Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data on the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.
17. Comparing laser induced plasmas formed in diode and excimer pumped alkali lasers.
Science.gov (United States)
Markosyan, Aram H
2018-01-08
Lasing on the D 1 transition (6 2 P 1/2 → 6 2 S 1/2 ) of cesium can be reached in both diode and excimer pumped alkali lasers. The first uses D 2 transition (6 2 S 1/2 → 6 2 P 3/2 ) for pumping, whereas the second is pumped by photoexcitation of ground state Cs-Ar collisional pairs and subsequent dissociation of diatomic, electronically-excited CsAr molecules (excimers). Despite lasing on the same D 1 transition, differences in pumping schemes enables chemical pathways and characteristic timescales unique for each system. We investigate unavoidable plasma formation during operation of both systems side by side in Ar/C 2 H 6 /Cs.
18. Duoplasmatron source modifications for 3He+ operation
Science.gov (United States)
Schmidt, C. W.; Popovic, M.
1998-02-01
A duoplasmatron ion source is used to produce 25 mA of 3He+ with a pulse width of ˜80 ms at 360 Hz for acceleration to 10.5 MeV. At this energy, 3He striking water or carbon targets can produce short lived isotopes of 11C, 13N, 15O, and 18F for medical positron emission tomography (PET). A duoplasmatron ion source was chosen originally since it is capable of a sufficient singly charged helium beam with an acceptable gas consumption. Stable long-term operation of the source required a change in the filament material to molybdenum, and a careful understanding of the oxide filament conditioning, operation and geometry. Other improvements, particularly in the electronics, were helpful to increasing the reliability. The source has operated for many months at ˜2.5% duty factor without significant problems and with good stability. We report here the effort that was done to make this source understandable and reliable.
19. Duoplasmatron source modifications for 3He+ Operation
International Nuclear Information System (INIS)
Schmidt, C.W.; Popovic, M.
1997-11-01
A duoplasmatron ion source is used to produce 25 mA of 3 He+ with a pulse width of ∼80 ms at 360 Hz for acceleration to 10.5 MeV. At this energy, 3 He striking water or carbon targets can produce short lived isotopes of 11 C, 13 N, 15 O and 18 F for medical positron emission tomography (PET). A duoplasmatron ion source was chosen originally since it is capable of a sufficient singly-charged helium beam with an acceptable gas consumption. Stable long-term operation of the source required a change in the filament material to molybdenum, and a careful understanding of the oxide filament conditioning, operation and geometry. Other improvements, particularly in the electronics, were helpful to increasing the reliability. The source has operated for many months at ∼2.5% duty factor without significant problems and with good stability. We report here the effort that was done to make this source understandable and reliable
20. Duoplasmatron source modifications for 3He+ operation
International Nuclear Information System (INIS)
Schmidt, C.W.; Popovic, M.
1998-01-01
A duoplasmatron ion source is used to produce 25 mA of 3 He + with a pulse width of ∼80ms at 360 Hz for acceleration to 10.5 MeV. At this energy, 3 He striking water or carbon targets can produce short lived isotopes of 11 C, 13 N, 15 O, and 18 F for medical positron emission tomography (PET). A duoplasmatron ion source was chosen originally since it is capable of a sufficient singly charged helium beam with an acceptable gas consumption. Stable long-term operation of the source required a change in the filament material to molybdenum, and a careful understanding of the oxide filament conditioning, operation and geometry. Other improvements, particularly in the electronics, were helpful to increasing the reliability. The source has operated for many months at ∼2.5% duty factor without significant problems and with good stability. We report here the effort that was done to make this source understandable and reliable
1. Modeling of a solar-pumped iodine laser
Science.gov (United States)
Wilson, J. W.; Lee, J. H.
1980-01-01
The direct conversion in space of solar radiation into laser radiation for power transmission to earth, satellites, or deep space probes shows promise as a reasonably simple technology and may have cost advantage in deployment and greater reliability compared to other methods of space power generation and transmission. The main candidates for solar pumping are the gas dynamic, photochemical, and direct photoexcited lasers. Here consideration is given to the photochemical reaction of alkyliodides which predominantly excite the I(2P1/2) state which then lases at 1.315 microns. The iodine ground state is eventually lost to reconstituting the gas or in the formation of molecular iodine. The rates at which the gas is required to be recycled through the laser system are modest. The side exposure at 100-fold solar concentration of a 100-m long tube with a 1 sq m cross section is estimated to provide 20 kW of continuous laser output. Scaling laws and optimum operating conditions of this system are discussed.
2. Large area electron beam pumped krypton fluoride laser amplifier
International Nuclear Information System (INIS)
Sethian, J.D.; Obenschain, S.P.; Gerber, K.A.; Pawley, C.J.; Serlin, V.; Sullivan, C.A.; Webster, W.; Deniz, A.V.; Lehecka, T.; McGeoch, M.W.; Altes, R.A.; Corcoran, P.A.; Smith, I.D.; Barr, O.C.
1997-01-01
Nike is a recently completed multi-kilojoule krypton fluoride (KrF) laser that has been built to study the physics of direct drive inertial confinement fusion. This paper describes in detail both the pulsed power and optical performance of the largest amplifier in the Nike laser, the 60 cm amplifier. This is a double pass, double sided, electron beam-pumped system that amplifies the laser beam from an input of 50 J to an output of up to 5 kJ. It has an optical aperture of 60 cm x 60 cm and a gain length of 200 cm. The two electron beams are 60 cm high x 200 cm wide, have a voltage of 640 kV, a current of 540 kA, and a flat top power pulse duration of 250 ns. A 2 kG magnetic field is used to guide the beams and prevent self-pinching. Each electron beam is produced by its own Marx/pulse forming line system. The amplifier has been fully integrated into the Nike system and is used on a daily basis for laser-target experiments. copyright 1997 American Institute of Physics
3. Hyperfine Structure Measurements of Antiprotonic $^3$He using Microwave Spectroscopy
CERN Document Server
Friedreich, Susanne
The goal of this project was to measure the hyperfine structure of $\\overline{\\text{p}}^3$He$^+$ using the technique of laser-microwave-laser spectroscopy. Antiprotonic helium ($\\overline{\\text{p}}$He$^+$) is a neutral exotic atom, consisting of a helium nucleus, an electron and an antiproton. The interactions of the angular momenta of its constituents cause a hyperfine splitting ({HFS}) within the energy states of this new atom. The 3\\% of formed antiprotonic helium atoms which remain in a metastable, radiative decay-dominated state have a lifetime of about 1-3~$\\mu$s. This time window is used to do spectroscopic studies. The hyperfine structure of $\\overline{\\text{p}}^4$He$^+$ was already extensively investigated before. From these measurements the spin magnetic moment of the antiproton can be determined. A comparison of the result to the proton magnetic moment provides a test of {CPT} invariance. Due to its higher complexity the new exotic three-body system of $\\overline{\\text{p}}^3$He$^+$ is a cross-check...
4. An actively mode-locked Ho: YAG solid laser pumped by a Tm: YLF laser
International Nuclear Information System (INIS)
Yao, B Q; Cui, Z; Wang, J; Duan, X M; Dai, T Y; Du, Y Q; Yuan, J H; Liu, W
2015-01-01
A continuous wave mode-locked (CWML) Ho: YAG laser based on an acousto-optic modulator (AOM) pumped by a 1.9 μm Tm: YLF laser is demonstrated. This is the first time a report on an active CWML Ho: YAG laser has been published. A maximum output power of 1.04 W at 2097.25 nm in the CWML regime is obtained at a pump power of 13.2 W, corresponding to a slope efficiency of 13.3%. The mode-locked pulse repetition frequency is 82.76 MHz and the single pulse energy is 12.57 nJ. The mode-locked pulse width is 102 ps measured through a no-background second harmonic autocorrelation with KTP as the nonlinear crystal. Furthermore, the M 2 factor is calculated to be 1.146. (letter)
5. Measurement of heat pump processes induced by laser radiation
Science.gov (United States)
Garbuny, M.; Henningsen, T.
1983-01-01
A series of experiments was performed in which a suitably tuned CO2 laser, frequency doubled by a Tl3AsSe37 crystal, was brought into resonance with a P-line or two R-lines in the fundamental vibration spectrum of CO. Cooling or heating produced by absorption in CO was measured in a gas-thermometer arrangement. P-line cooling and R-line heating could be demonstrated, measured, and compared. The experiments were continued with CO mixed with N2 added in partial pressures from 9 to 200 Torr. It was found that an efficient collisional resonance energy transfer from CO to N2 existed which increased the cooling effects by one to two orders of magnitude over those in pure CO. Temperature reductions in the order of tens of degrees Kelvin were obtained by a single pulse in the core of the irradiated volume. These measurements followed predicted values rather closely, and it is expected that increase of pulse energies and durations will enhance the heat pump effects. The experiments confirm the feasibility of quasi-isentropic engines which convert laser power into work without the need for heat rejection. Of more immediate potential interest is the possibility of remotely powered heat pumps for cryogenic use, such applications are discussed to the extent possible at the present stage.
6. X-ray-induced thinning of 3He and 3He/4He mixture films
International Nuclear Information System (INIS)
Penanen, Konstantin; Fukuto, Masafumi; Silvera, Isaac F.; Pershan, Peter
2000-01-01
Films of isotopic mixtures of helium have been studied using x-ray specular reflectivity techniques. In contrast with superfluid 4 He films, x-ray exposure causes a reduction in the thickness of 4 He films above the superfluid transition as well as films of pure 3 He and 3 He/ 4 He mixtures. One proposed model that could account for this effect is a charging model, in which thinning is caused by electrostatic pressure of free charges that accumulate on the helium surface. Unfortunately, this model is not fully consistent with all of the experimental observations. A localized heating model, in which indirect heating of the film causes it to thin would explain the data if there were dissipative film flow in the 3 He/ 4 He mixtures at temperatures where the bulk is superfluid. We argue that various published experimental results suggest such an effect. In this model, film thinning data for dilute 3 He/ 4 He films indicates dissipation that is linear in 3 He content of the film over two orders of magnitude
7. Microscopic theory of normal liquid 3He
International Nuclear Information System (INIS)
Nafari, N.; Doroudi, A.
1994-03-01
We have used the self-consistent scheme proposed by Singwi, Tosi, Land and Sjoelander (STLS) to study the properties of normal liquid 3 He. By employing the Aziz potential (HFD-B) and some other realistic pairwise interactions, we have calculated the static structure factor, the pair-correlation function, the zero sound frequencies as a function of wave-vector, and the Landau parameter F s 0 for different densities. Our results show considerable improvement over the Ng-Singwi's model potential of a hard core plus an attractive tail. Agreement between our results and the experimental data for the static structure factor and the zero sound frequencies is fairly good. (author). 30 refs, 6 figs, 2 tabs
8. High-performace cladding-pumped erbium-doped fibre laser and amplifier
International Nuclear Information System (INIS)
Kotov, L V; Likhachev, M E; Bubnov, M M; Medvedkov, O I; Lipatov, D S; Vechkanov, N N; Guryanov, Aleksei N
2012-01-01
We report cladding-pumped erbium-doped fibre laser and amplifier configurations. Through fibre design optimisation, we have achieved a record-high laser slope efficiency, 40 % with respect to absorbed pump power (λ = 976 nm), and an output power of 7.5 W. The erbium-doped fibre amplifier efficiency reaches 32 %.
9. Development of high-power optically-pumped far-infrared lasers for plasma diagnostics
International Nuclear Information System (INIS)
Yamanaka, Masanobu; Yamanaka, Tatsuhiko; Mitsuishi, Akiyoshi; Fujita, Shigeru; Tsunawaki, Yoshiaki.
1982-01-01
The activities for developing an over 0.1-MW optically-pumped 385-μm D 2 O laser and a CW optically-pumped 382.9-μm CH 2 F 2 laser as local oscillator for measurement of ion temperature in Tokamaks are described. (author)
10. Backward elastic p3He-scattering and high momentum components of 3He wave function
International Nuclear Information System (INIS)
Uzikov, Yu.N.
1998-01-01
It is shown that owing to a dominance of np-pair transfer mechanism of backward elastic p 3 He-scattering for incident proton kinetic energies T p > 1 GeV the cross section of this process is defined mainly by the values of the Faddeev component of the wave function of 3 He nucleus, φ 23 (q 23 , p 1 ), at high relative momenta q 23 > 0.6 GeV/c of the NN-pair in the 1 S 0 -state and at low spectator momenta p 1 ∼ 0 - 0.2 GeV/c
11. Laser Demonstration and Performance Characterization of an Optically Pumped Alkali Laser System
Science.gov (United States)
2010-09-01
ground state 2S1/2 on the D1 line. An example of this is shown in Figure 1 from Krupke’s original paper for the rubidium transitions. In addition to...any of the alkali’s listed in Table 1 can be used in a three-level laser system to create a DPAL system. However, for practical applications...Figure 39, the pump energy per pulse is 3 mJ, providing a pump intensity of ≅ 2 x 106 W/cm2, much higher than the saturation intensity of Isat = (hν
12. High-average-power diode-pumped Yb: YAG lasers
International Nuclear Information System (INIS)
Avizonis, P V; Beach, R; Bibeau, C M; Emanuel, M A; Harris, D G; Honea, E C; Monroe, R S; Payne, S A; Skidmore, J A; Sutton, S B
1999-01-01
A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M(sup 2)= 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M(sup 2) value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M(sup 2) and lt; 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods
13. High-efficiency diode-pumped femtosecond Yb:YAG ceramic laser
DEFF Research Database (Denmark)
Zhou, Binbin; Wei, Z.Y.; Zou, Y.W.
2010-01-01
A highly efficient diode-end-pumped femtosecond Yb:yttrium aluminum garnet (YAG) ceramic laser was demonstrated. Pumped by a 968 nm fiber-coupled diode laser, 1.9 W mode-locked output power at a repetition rate of 64.27 MHz was obtained with 3.5 W absorbed pump power, corresponding to a slope...... efficiency of 76%. Our measurement showed that the pulse duration was 418 fs with the central wavelength of 1048 nm....
14. High-brightness fiber-coupled pump laser development
Science.gov (United States)
Price, Kirk; Karlsen, Scott; Leisher, Paul; Martinsen, Robert
2010-02-01
We report on the continued development of high brightness laser diode modules at nLIGHT Photonics. These modules, based on nLIGHT's PearlTM product platform, demonstrate excellence in output power, brightness, wavelength stabilization, and long wavelength performance. This system, based on 14 single emitters, is designed to couple diode laser light into a 105 μm fiber at an excitation NA of under 0.14. We demonstrate over 100W of optical power at 9xx nm with a diode brightness exceeding 20 MW/cm2-str with an operating efficiency of approximately 50%. Additional results show over 70W of optical coupled at 8xx nm. Record brilliance at wavelengths 14xx nm and longer will also be demonstrated, with over 15 W of optical power with a beam quality of 7.5 mm-mrad. These results of high brightness, high efficiency, and wavelength stabilization demonstrate the pump technology required for next generation solid state and fiber lasers.
15. Single-mode pulsed dye laser pumped by using a diode-pumped Nd:YAG laser with a long pulse width
CERN Document Server
Yi, J H; Moon, H J; Rho, S P; Han, J M; Rhee, Y J; Lee, J M
1999-01-01
The lasing characteristics of a single-mode dye laser pumped by using a diode-pumped solid-state laser (DPSSL) with a high repetition rate is described. A 45-mm-long Nd:YAG rod was pumped by three CW diode arrays and it was acousto-optically Q-switched. A KTP crystal was used for intracavity frequency doubling. The pulse width of the laser ranged from 90 ns to 200 ns, depending on the diode current and the Q-switching frequency. The single-mode dye laser had a grazing incidence configuration. The pulse width of the dye laser was reduced to about 1/8 of the pumping laser pulse width. The effects of the DPSSL Q-switching frequency, the driving current, and the cavity loss on the dye laser pulse width were investigated by using a simple plane-parallel cavity. From the measured pulse width of the dye laser as a function of the reflectivity of the dye laser output coupler, we found that the cavity loss due to the frequency selection elements and the output coupler should be less than 70 % in order to avoid a drast...
16. Single-mode pulsed dye laser pumped by using a diode-pumped Nd:YAG laser with a long pulse width
International Nuclear Information System (INIS)
Yi, Jong Hoon; Kim, Jin Tae; Moon, Hee Jong; Rho, Si Pyo; Han, Jae Min; Rhee, Yong Joo; Lee, Jong Min
1999-01-01
The lasing characteristics of a single-mode dye laser pumped by using a diode-pumped solid-state laser (DPSSL) with a high repetition rate is described. A 45-mm-long Nd:YAG rod was pumped by three CW diode arrays and it was acousto-optically Q-switched. A KTP crystal was used for intracavity frequency doubling. The pulse width of the laser ranged from 90 ns to 200 ns, depending on the diode current and the Q-switching frequency. The single-mode dye laser had a grazing incidence configuration. The pulse width of the dye laser was reduced to about 1/8 of the pumping laser pulse width. The effects of the DPSSL Q-switching frequency, the driving current, and the cavity loss on the dye laser pulse width were investigated by using a simple plane-parallel cavity. From the measured pulse width of the dye laser as a function of the reflectivity of the dye laser output coupler, we found that the cavity loss due to the frequency selection elements and the output coupler should be less than 70 % in order to avoid a drastically reduced pulse width
17. Recent advancements of wide-angle polarization analysis with 3He neutron spin filters
International Nuclear Information System (INIS)
Chen, W.C.; Gentile, T.R.; Ye, Q.; Kirchhoff, A.; Watson, S.M.; Rodriguez-Rivera, J.A.; Qiu, Y.; Broholm, C.
2016-01-01
Wide-angle polarization analysis with polarized 3 He based neutron spin filters (NSFs) has recently been employed on the Multi-Axis Crystal Spectrometer (MACS) at the National Institute of Standards and Technology Center for Neutron Research (NCNR). Over the past several years, the apparatus has undergone many upgrades to address the fundamental requirements for wide angle polarization analysis using spin exchange optical pumping based 3 He NSFs. In this paper, we report substantial improvements in the on-beam-line performance of the apparatus and progress toward routine user capability. We discuss new standard samples used for 3 He NSF characterization and the flipping ratio measurement on MACS. We further discuss the management of stray magnetic fields produced by operation of superconducting magnets on the MACS instrument, which can significantly reduce the 3 He polarization relaxation time. Finally, we present the results of recent development of horseshoe-shaped wide angle cells. (paper)
18. Experimental study of solar pumped laser for magnesium-hydrogen energy cycle
International Nuclear Information System (INIS)
Yabe, T; Okamoto, Y; Ohkubo, T; Uchida, S; Yoshida, K; Bagheri, B; Funatsu, T; Mabuti, A; Oyama, A; Nakagawa, K; Oishi, T; Daito, K; Nakatsuka, M; Yoshida, M; Motokoshi, S; Sato, Y; Baasandash, C; Nakayama, N; Yanagaidani, K
2008-01-01
24.4 W of laser output has been obtained by sun-pumped, Cr-codoped Nd:yttrium aluminum garnet ceramic. The water-cooled laser rod was pumped with a Fresnel lens focusing the natural sunlight. By using the advantages of the Fresnel lenses, the maximum output for unit area of sunlight was 18.7 W/m 2 . Direct concentrated solar illumination was used to pump a 9mm-diameter, 100mm length rod of Cr:Nd:YAG, which was obtained 9%-14% slope efficiency for the laser output. We have analyzed the Cr:YAG laser medium and found it to be an excellent high-power laser candidate for direct solar-pumping schemes which enhances the laser output about 1.8 times more than Nd:YAG
19. Highly scalable, resonantly cladding-pumped, Er-doped fiber laser with record efficiency.
Science.gov (United States)
Dubinskii, M; Zhang, J; Ter-Mikirtychev, V
2009-05-15
We report the performance of a resonantly cladding-pumped, Yb-free, Er-doped fiber laser. We believe this is the first reported resonantly cladding-pumped fiber-Bragg-grating-based, Er-doped, large-mode-area (LMA) fiber laser. The laser, pumped by fiber-coupled InGaAsP/InP laser diode modules at 1,532.5 nm, delivers approximately 48 W of cw output at 1,590 nm. It is believed to be the highest power ever reported from a Yb-free Er-doped LMA fiber. This fully integrated laser also has the optical-to-optical efficiency of approximately 57%, to the best of our knowledge, the highest efficiency reported for cladding-pumped unidirectionally emitting Er-doped laser.
20. Low-concentrated solar-pumped laser via transverse excitation fiber-laser geometry.
Science.gov (United States)
Masuda, Taizo; Iyoda, Mitsuhiro; Yasumatsu, Yuta; Endo, Masamori
2017-09-01
We demonstrate an extremely low-concentrated solar-pumped laser (SPL) using a fiber laser with transverse excitation geometry. A low concentration factor is highly desired in SPLs to eliminate the need for precise solar tracking and to considerably increase the practical applications of SPL technology. In this Letter, we have exploited the intrinsic low-loss property of silica fibers to compensate for the extremely low gain coefficient of the weakly pumped active medium. A 40 m long Nd 3+ -doped fiber coil is packed in a ring-shaped chamber filled with a sensitizer solution. We demonstrated a lasing threshold that is 15 times the concentration of natural sunlight and two orders of magnitude smaller than those of conventional SPLs.
1. Cryogenic Yb:YAG laser pumped by VBG-stabilized narrowband laser diode at 969 nm
Czech Academy of Sciences Publication Activity Database
Jambunathan, Venkatesan; Horáčková, Lucie; Navrátil, Petr; Lucianetti, Antonio; Mocek, Tomáš
2016-01-01
Roč. 128, č. 12 (2016), s. 1328-1331 ISSN 1041-1135 R&D Projects: GA MŠk EE2.3.20.0143; GA ČR GA14-01660S Grant - others:HILASE(XE) CZ.1.05/2.1.00/01.0027; HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : Diode-pumped * cryogenic * volume Bragg grating * Yb doped * solid state lasers Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.375, year: 2016
2. Energy Efficiency of an Intracavity Coupled, Laser-Driven Linear Accelerator Pumped by an External Laser
International Nuclear Information System (INIS)
Neil Na, Y.C.; Siemann, R.H.; SLAC; Byer, R.L.; Stanford U., Phys. Dept.
2005-01-01
We calculate the optimum energy efficiency of a laser-driven linear accelerator by adopting a simple linear model. In the case of single bunch operation, the energy efficiency can be enhanced by incorporating the accelerator into a cavity that is pumped by an external laser. In the case of multiple bunch operation, the intracavity configuration is less advantageous because the strong wakefield generated by the electron beam is also recycled. Finally, the calculation indicates that the luminosity of a linear collider based on such a structure is comparably small if high efficiency is desired
3. Low-power photolytically pumped lasers: Final technical report
International Nuclear Information System (INIS)
Messing, I.; Lorents, D.C.; Eckstrom, D.J.
1987-08-01
We have carried out an extensive series of measurements of the time-resolved Xe 2 * emission spectra following optical pumping by a short-pulse F 2 laser at 157.6 nm. Most measurements were performed using a gated Optical Multichannel Analyzer detector; we also made measurements using a scanning monochromator fitted with a photomultiplier and using a boxcar integrator for time resolution. The two sets of results agree well and show that both the singlet and triplet emission bands are broader than expected and have center wavelengths closer together than expected. Measurements were performed both at room temperature and at elevated (140 0 C) and reduced (-27 0 C) temperatures. The broad bandwidth of the individual spectral bands was unexpected and conflicted with a previous spectral measurement using optical pumping by the Xe* resonance line from a microwave discharge lamp. Therefore, we also performed a series of spectral measurements using this type of optical pumping. We achieved good agreement with some previous results in the literature, but not with the result in question. We conclude that the present results are reliable. The results presented in this report provide the first definitive measurement of the individual excimer emissions from each of the Xe 2 (0/sub u/ + ) and Xe 2 (1/sub u/) states. From these measurements and the known ground state potential, we derived a 1/sub u/ potential that reproduces the emission band very well. However, the 1/sub u/ potential is in substantial disagreement with the recent 1/sub u/ potential derived by the Toronto group. 13 refs., 32 figs., 3 tabs
4. Direct energy conversion and neutral beam injection for catalyzed D and D-3He tokamak reactors
International Nuclear Information System (INIS)
Blum, A.S.; Moir, R.W.
1977-01-01
The calculated performance of single stage and Venetian blind direct energy converters for Catalyzed D and D- 3 He Tokamak reactors are discussed. Preliminary results on He pumping are outlined. The efficiency of D and T neutral beam injection is reviewed
5. Non-uniform 3He polarization formed by multiple collisions of a fast 3He+ ion with polarized Rb vapor in a strong magnetic field
International Nuclear Information System (INIS)
Arimoto, Y.; Yonehara, K.; Yamagata, T.; Tanaka, M.
2001-01-01
We investigated the spatial distribution of a polarization in 3 He beam expected from a novel polarized 3 He ion source based on electron pumping, i.e., multiple electron capture and stripping collisions of an incident fast 3 He + ion with a polarized Rb vapor in a strong axial magnetic field. For this purpose, a Monte Carlo simulation was carried out for 19 keV 3 He + ions with varying Rb vapor thickness, magnetic field, and beam emittance. The calculated results showed a distribution of the 3 He polarization that we call a 'polarization hole', which has a low polarization area around the beam axis. The parameters characterizing the polarization hole, i.e., the polarization and radius of the hole, were found to depend on the Rb vapor thickness, the magnetic field, the beam size, and the angular divergence of the initial beam. These parameters were successfully reproduced with analytical functions deduced from a probability density function prescription. This provides a powerful tool to treat complex phenomena of multiple collisions in strong magnetic fields without performing time-consuming Monte Carlo calculations
6. Compact corner-pumped Nd:YAG/YAG composite slab 1319 nm/1338 nm laser
International Nuclear Information System (INIS)
Liu, H; Gong, M; Wushouer, X; Gao, S
2010-01-01
A corner-pumped type is a new pumping type in the diode-pumped solid-state lasers, which has the advantages of high pump efficiency and favorable pump uniformity. A corner-pumped Nd:YAG/YAG composite slab continuous-wave 1319 nm/1338 nm dual-wavelength laser is first demonstrated in this paper. When the cavity length is 25 mm, the maximal output power is up to 7.62 W with a slope efficiency of 16.6% and an optical-to-optical conversion efficiency of 17%. The corresponding spectral line widths of 1319 nm laser and 1338 nm laser are 0.11 and 0.1 nm, respectively. The short-term instability of the output power is better than 1% when the pumping power is 39.5 W. The experimental results show that a corner-pumped type is a kind of feasible schedules in the design of diode-pumped solid-state 1.3 μm lasers with low or medium output powers
7. Manipulating the wavelength-drift of a Tm laser for resonance enhancement in an intra-cavity pumped Ho laser.
Science.gov (United States)
Huang, Haizhou; Huang, Jianhong; Liu, Huagang; Li, Jinhui; Lin, Zixiong; Ge, Yan; Dai, Shutao; Deng, Jing; Lin, Wenxiong
2018-03-05
We demonstrate an enhancement mechanism and thermal model for intra-cavity pumped lasers, where resonance enhancement in intra-cavity pumped Ho laser was achieved by manipulating the wavelength-drift nature of the Tm laser for the first time. Optical conversion efficiency of 37.5% from an absorbed 785 nm diode laser to a Ho laser was obtained with a maximum output power of 7.51 W at 2122 nm, which is comparable to the conversion efficiency in 1.9 μm LD pumped Ho lasers. Meanwhile, more severe thermal effects in the Ho-doped gain medium than the Tm-doped one at high power operation were verified based on the built thermal model. This work benefits the design or evaluation of intra-cavity pumped lasers, and the resonance enhancement originated from the difference in reabsorption loss between stark levels at the lasing manifolds of quasi-three-level rare-earth ions has great interest to improve the existing intra-cavity pumped lasers or explore novel lasers.
8. Continued advances in high brightness fiber-coupled laser modules for efficient pumping of fiber and solid-state lasers
Science.gov (United States)
Hemenway, M.; Chen, Z.; Urbanek, W.; Dawson, D.; Bao, L.; Kanskar, M.; DeVito, M.; Martinsen, R.
2018-02-01
Both the fibber laser and diode-pumped solid-state laser market continue to drive advances in pump diode module brightness. We report on the continued progress by nLIGHT to develop and deliver the highest brightness diode-laser pumps using single-emitter technology. Continued advances in multimode laser diode technology [13] and fiber-coupling techniques have enabled higher emitter counts in the element packages, enabling us to demonstrate 305 W into 105 μm - 0.16 NA. This brightness improvement is achieved by leveraging our prior-reported package re-optimization, allowing an increase in the emitter count from two rows of nine emitters to two rows of twelve emitters. Leveraging the two rows off twelve emitter architecture,, product development has commenced on a 400 W into 200 μm - 00.16 NA package. Additionally, the advances in pump technology intended for CW Yb-doped fiber laser pumping has been leveraged to develop the highest brightness 793 nm pump modules for 2 μm Thulium fiber laser pumping, generating 150 W into 200 μm - 0.18 NA and 100 W into 105 μm - 0.15 NA. Lastly, renewed interest in direct diode materials processing led us to experiment with wavelength multiplexing our existing state of the art 200 W, 105 μm - 00.15 NA package into a combined output of 395 WW into 105 μm - 0.16 NA.
9. The sup(40,44,48)Ca(3He, 3He) and (3He, 4He) reactions at 50 MeV
International Nuclear Information System (INIS)
Griffiths, R.J.; Duggan, F.; Clarke, N.M.
1981-01-01
Measurements have been made of the ( 3 He, 3 He) and ( 3 He, 4 He) reactions on the isotopes of calcium 40 Ca, 44 Ca and 48 Ca at an energy of 50.4 MeV. The results have been analysed with conventional optical potentials and DWBA. The adequacy of the former and inadequacy of the latter for reactions with composite particles is discussed. (author)
10. Optically pumped alkali laser and amplifier using helium-3 buffer gas
Science.gov (United States)
Beach, Raymond J.; Page, Ralph; Soules, Thomas; Stappaerts, Eddy; Wu, Sheldon Shao Quan
2010-09-28
In one embodiment, a laser oscillator is provided comprising an optical cavity, the optical cavity including a gain medium including an alkali vapor and a buffer gas, the buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Additionally, an optical excitation source is provided. Furthermore, the laser oscillator is capable of outputting radiation at a first frequency. In another embodiment, an apparatus is provided comprising a gain medium including an alkali vapor and a buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Other embodiments are also disclosed.
11. Diode-pumped cw Tm3+:YAlO3 laser
International Nuclear Information System (INIS)
Borodin, N I; Kryukov, P V; Shestakov, A V; Popov, A V; Ushakov, S N
2005-01-01
The output parameters of a Tm 3+ :YAlO 3 laser pumped by laser diodes in the spectral region 802-810 nm are studied. The output cw power exceeded 10 W for the total efficiency above 30%. The laser wavelength varies in the range from 1946 to 1985 nm and is determined by the pump power and resonator losses in this spectral region. The efficiency of cross relaxation process during the population of the 3 F 4 laser level is measured. (lasers)
12. D2O laser pumped by an injection-locked CO2 laser for ion-temperature measurements
International Nuclear Information System (INIS)
Okada, Tatsuo; Ohga, Tetsuaki; Yokoo, Masakazu; Muraoka, Katsunori; Akazaki, Masanori.
1986-01-01
The cooperative Thomson scattering method is one of the various new techniques proposed for measuring the temperature of ions in nuclear fusion critical plasma, for which a high-performance FIR laser pumped by an injection-locked CO 2 laser is required. This report deals with D 2 O laser with a wavelength of 385 μm which is pumped by injection-locked single-mole TEA CO 2 laser composed of a driver laser and an output-stage laser. A small-sized automatic pre-ionization type laser is employed for the driver. The resonator of the driver laser consists of a plane grating of littrow arrangement and ZnSe plane output mirrors with reflection factor of 50 %. An aperture and ZnSe etalon are inserted in the resonator to produce single transverse- and longitudinal-mode oscillation, respectively. The output-stage laser is also of the automatic pre-ionization type. Theoretically, an injection power of 0.1 pW/mm 3 is required for a CO 2 laser. Single-mode oscillation of several hundred nW/mm 3 can be produced by the CO 2 laser used in this study. Tuning of the output-stage laser is easily controlled by the driver laser. High stability of the injection-locked operation is demonstrated. CO 2 laser beam is introduced into the D 2 O laser through a KCl window to excite D 2 O laser beam in the axial direction. Input and output characteristics of the D 2 O laser are shown. Also presented are typical pulse shapes from the D 2 O laser pumped by a free-running CO 2 laser pulse or by an injection-locked single-mode CO 2 laser pulse. (Nogami, K.)
13. Theoretical analyses of an injection-locked diode-pumped rubidium vapor laser.
Science.gov (United States)
Cai, He; Gao, Chunqing; Liu, Xiaoxu; Wang, Shunyan; Yu, Hang; Rong, Kepeng; An, Guofei; Han, Juhong; Zhang, Wei; Wang, Hongyuan; Wang, You
2018-04-02
Diode-pumped alkali lasers (DPALs) have drawn much attention since they were proposed in 2001. The narrow-linewidth DPAL can be potentially applied in the fields of coherent communication, laser radar, and atomic spectroscopy. In this study, we propose a novel protocol to narrow the width of one kind of DPAL, diode-pumped rubidium vapor laser (DPRVL), by use of an injection locking technique. A kinetic model is first set up for an injection-locked DPRVL with the end-pumped configuration. The laser tunable duration is also analyzed for a continuous wave (CW) injection-locked DPRVL system. Then, the influences of the pump power, power of a master laser, and reflectance of an output coupler on the output performance are theoretically analyzed. The study should be useful for design of a narrow-linewidth DPAL with the relatively high output.
14. Localization of the pumping reflector for a Nd:YAG laser
Energy Technology Data Exchange (ETDEWEB)
Kim, Kwang Suk; Kim, Chul Joong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)
1994-12-01
For the first year plan of this program, the pumping reflectors, which are gold plated reflectors and ceramic diffuse reflectors, of the Nd:YAG laser have been localized. The laser output performances with these reflectors have been investigated. Developed reflectors can be applied successfully to our commercialized Nd:YAG laser which was worked in previous project. We designed the optical pumping system with GaAlAs diode laser bar to improve the pumping efficiency. Moreover, we investigated a simple pumping technique without changing the fleshlamp, which makes the Nd:YAG laser operate in a cw, a pulsed, and a mixed of the two mode. We expert many new applications of this diversification of output pulse shapes in industry and in medicine. 38 figs, 9 tabs, 18 refs. (Author).
15. Theoretical study on the thermal and optical features of a diode side-pumped alkali laser
Science.gov (United States)
Han, Juhong; Liu, Xiaoxu; Wang, Hongyuan; Cai, He; An, Guofei; Zhang, Wei; Wang, You
2018-03-01
As one of the most hopeful candidates to achieve high power performances, a diode-pumped alkali laser (DPAL) has attracted a lot of attention in the last decade. Comparing with a diode end-pumped alkali laser (DEPAL), a diode side-pumped alkali laser (DSPAL) has great potentiality to realize an even-higher output of alkali lasers. However, there are few related researching studies concern DSPAL. In this paper, we introduce a theoretical model to investigate the physical features of a double-directions side-pumped alkali laser. The distributions of the population density, temperature, and absorption power at the cross section of a vapor cell are systematically studied. The analyses should be valuable for design of a steady high-powered DPAL.
International Nuclear Information System (INIS)
Mel'kumov, Mikhail A; Bufetov, Igor' A; Bubnov, M M; Shubin, Aleksei V; Semenov, S L; Dianov, Evgenii M
2005-01-01
Pump radiation transfer is studied experimentally in multi-element first cladding laser fibres. A model of this process is proposed, which is in good agreement with experimental results. An all-fibre single-mode cw ytterbium laser based on a three-element first cladding fibre with an output power of 100W is fabricated. (lasers)
17. Kilowatt average power 100 J-level diode pumped solid state laser
Czech Academy of Sciences Publication Activity Database
Mason, P.; Divoký, Martin; Ertel, K.; Pilař, Jan; Butcher, T.; Hanuš, Martin; Banerjee, S.; Phillips, J.; Smith, J.; De Vido, M.; Lucianetti, Antonio; Hernandez-Gomez, C.; Edwards, C.; Mocek, Tomáš; Collier, J.
2017-01-01
Roč. 4, č. 4 (2017), s. 438-439 ISSN 2334-2536 R&D Projects: GA MŠk LO1602; GA MŠk LM2015086 Institutional support: RVO:68378271 Keywords : diode-pumped * solid state * laser Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 7.727, year: 2016
18. Laser diode pumped ND: Glass slab laser for inertial fusion energy
International Nuclear Information System (INIS)
Yamanaka, M.; Kanabe, T.; Matsui, H.
2001-01-01
As a first step of a driver development for the inertial fusion energy, we are developing a laser-diode-pumped zig-zag Nd:glass slab laser amplifier system HALNA 10 (High Average-power Laser for Nuclear-fusion Application) which can generate an output of 10 J per pulse at 1053 nm in 10 Hz operation. The water-cooled zig-zag Nd:glass slab is pumped from both sides by 803-nm AlGaAs laser-diode(LD) module; each LD module has an emitting area of 420 mm x 10 mm and two LD modules generated in total 218 (max.) kW peak power with 2.6kW/cm 2 peak intensity at 10 Hz repetition rate. We have obtained in a preliminary experiment a 8.5 J output energy at 0.5 Hz with beam quality of 2 times diffraction limited far-field pattern, which nearly confirmed our conceptual design. (author)
19. Investigation of diode-laser pumped thulium-doped fluoride lasers; Investigacao de lasers de floureto dopados com tulio e bombeados por diodo-laser
Energy Technology Data Exchange (ETDEWEB)
Matos, Paulo Sergio Fabris de
2006-07-01
Tunable lasers emitting around 2.3 mum region are important in many areas, like gas detection, remote sensing and medical applications. Thulium has a large emission spectra around 2.3 mum with demonstrated tuning range of 2.2-2.45 mum using the YLF host. For efficient pump absorption, a high concentration sensitizer like ytterbium can be used. We demonstrate quasi-cw operation of the Yb:Tm:YLF laser, pumped at 960 nm with a 20 W diode bar achieving the highest output power reported so far of 620 mW. Simultaneous pumping of the 2.3 mm Yb:Tm:YLF laser at 685 nm and 960 nm is demonstrated, showing higher slope efficiency than 960 nm alone. Numerical simulations and analytical models show the best ratio of pump power between both wavelengths. (author)
20. Diode laser pumped solid state laser. Part IV. ; Noise analysis. Handotai laser reiki kotai laser. 4. ; Noise kaiseki
Energy Technology Data Exchange (ETDEWEB)
Sakurai, H.; Seno, T.; Tanabe, Y. (Asahi Glass Co. Ltd., Tokyo (Japan))
1991-06-10
Concerning the second harmonic generation(SHG) of diode laser pumped solid state laser using a nonlinear optical material, the researches are carried out to pracitically apply to the optical pickup. Therefore, the reduction of output optical noise has become the important researching subject. The theoretical and experimental analyses of noise generating mechanism were carried out for the system in which Nd;YAG as the laser diode and KTP (KTiOPO {sub 4}) as the nonlinear optical crystal were used. The following findings for the noise generating mechanism could be obtained: The competitive interaction between the polarization modes was dominant noise mechanism in the high frequency range from 1 to 20MHz and the noise could be removed sufficiently by using the QWP(quarter wave plate). On the other hand, the noise observed in the low frequency range from 100 to 200kHz depended on the resonance length, agreed qualitatively with the theoretical analysis of the noise to the competitive longitudinal modes and agreed quantitatively with the noise generating frequency range. 10 refs., 13 figs., 1 tab.
1. 885-nm laser diode array pumped ceramic Nd:YAG master oscillator power amplifier system
Science.gov (United States)
Yu, Anthony W.; Li, Steven X.; Stephen, Mark A.; Seas, Antonios; Troupaki, Elisavet; Vasilyev, Aleksey; Conley, Heather; Filemyr, Tim; Kirchner, Cynthia; Rosanova, Alberto
2010-04-01
The objective of this effort is to develop more reliable, higher efficiency diode pumped Nd:YAG laser systems for space applications by leveraging technology investments from the DoD and other commercial industries. Our goal is to design, build, test and demonstrate the effectiveness of combining 885 nm laser pump diodes and the use of ceramic Nd:YAG for future flight missions. The significant reduction in thermal loading on the gain medium by the use of 885 nm pump lasers will improve system efficiency.
2. Photonic crystal fibers for supercontinuum generation pumped by a gain-switched CW fiber laser
DEFF Research Database (Denmark)
Larsen, Casper; Noordegraaf, Danny; Hansen, Kim P.
2012-01-01
Supercontinuum generation in photonics crystal fibers (PCFs) pumped by CW lasers yields high spectral power density and average power. However, such systems require very high pump power and long nonlinear fibers. By on/off modulating the pump diodes of the fiber laser, the relaxation oscillations...... of the laser can be exploited to enhance the broadening process. The physics behind the supercontinuum generation is investigated by sweeping the fiber length, the zero dispersion wavelength, and the fiber nonlinearity. We show that by applying gain-switching a high average output power of up to 30 W can...
3. Study of a low power dissipation, miniature laser-pumped rubidium frequency standard
Institute of Scientific and Technical Information of China (English)
Liu Guo-Bin; Zhao Feng; Gu Si-Hong
2009-01-01
This paper studies a miniature low power consumption laser-pumped atom vapour cell clock scheme. Pumping 87Rb with a vertical cavity surface emitting laser diode pump and locking the laser frequency on a Doppler-broadened spectral line,it records a 5×10-11τ-1/2 (τ<500 s) frequency stability with a table-top system in a primary experiment.The study reveals that the evaluated scheme is at the level of 2.7 watts power consumption,90 cm3 volume and 10-12τ- 1/2 short-term frequency stability.
4. Possibilities for breakeven and ignition of D-3He fusion fuel in a near term tokamak
International Nuclear Information System (INIS)
Emmert, G.A.; El-Guebaly, L.; Kulcinski, G.L.; Santarius, J.F.; Scharer, J.E.; Sviatoslavsky, I.N.; Walstrom, P.L.; Klinghoefer, R.; Wittenberg, J.L.
1988-09-01
The recent realization that the moon contains a large amount of the isotope 3 He has rekindled interest in the D- 3 He fuel cycle. In this study we consider the feasibility of investigating D- 3 He reactor plasma conditions in a tokamak of the NET/INTOR class. We have found that, depending on the energy confinement scaling law, energy breakeven may be achieved without significant modification to the NET design. The best results are for the more optimistic ASDEX H-mode scaling law. Kaye-Goldston scaling with a modest improvement due to the H-mode is more pessimistic and makes achieving breakeven more difficult. Significant improvement in Q (ratio of the fusion power to the injected power), or the ignition margin, can be achieved by taking advantage of the much reduced neutron production of the D- 3 He fuel cycle. Removal of the tritium producing blanket and replacing the inboard neutron shield by a thinner shield optimized for the neutron spectrum in D- 3 He allows the plasma to be increased without changing the magnetic field at the toroidal field magnet. This allows the plasma to achieve higher beta and Q values up to about 3. The implications of D- 3 He operation for fast ion loss, neutron shielding, heat loads on the first wall and divertor, plasma refuelling, changes to the poloidal field coil system, and pumping of the helium from the vacuum chamber are considered in the report. (orig.)
5. Effect of pump-beam conditions on dual polarization oscillations in a microchip Nd:GdVO{sub 4} laser
Energy Technology Data Exchange (ETDEWEB)
Lin, C-C; Jiang, I-M [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Ko, J-Y; Tsai, K-T; Cheng, Y-T; Ho, M-C, E-mail: [email protected] [Department of Physics, National Kaohsiung Normal University, Kaohsiung 824, Taiwan (China)
2009-08-28
This study investigated the input-output characteristics of a laser-diode-end-pumped microchip Nd:GdVO{sub 4} laser under different pump-beam focusing conditions by varying the magnifications of the microscope objective lenses and pump-beam positions on a chip. Dual-polarization oscillations were generated in the entire pump region using pumping conditions associated with different temperature gradients.
6. Theoretical model and simulations for a cw exciplex pumped alkali laser.
Science.gov (United States)
Huang, Wei; Tan, Rongqing; Li, Zhiyong; Lu, Xiaochuan
2015-12-14
The Exciplex Pumped Alkali Laser (XPAL) system, which is similar to DPAL (Diode Pumped Alkali vapor Laser), has been demonstrated in mixtures of Cs vapor, Ar, with and without ethane. Unlike DPAL, it uses the broadband absorption blue satellite of the alkali D2 line, created by naturally occuring collision pairs. For example, Cs-Ar collision pairs have an absorption width which is as wide as the one of commercial semiconductor diode lasers. A continuous wave XPAL four-level theoretical model is presented in this paper. More factors are considered, such as the spectral dependence of pumped laser absorption for broadband pumping and the longitudinal population variation. Some intra-cavity details, such as longitudinal distributions of pumped laser and alkali laser, can also be solved well. The predictions of optical-to-optical efficiency as a function of temperature and pumped laser intensity are presented. The model predicts that there is an optimum value of temperature or pumped laser intensity. The analysis of the influence of cell length on optical-to-optical efficiency shows that a better performance can be achieved when using longer cell. The prediction of influence of Ar concentration and reflectivity of output coupler shows that higher optical-to-optical efficiency could be achieved if lower reflectivity of output coupler and higher Ar concentration are used. The optical-to-optical efficiency as high as 84% achieved by optimizing configuration with the pumped intensity of 5 × 10⁷ W/cm² presented shows that broadband pumped four-level XPAL system has a potential of high optical-to-optical efficiency.
7. LD-pumped erbium and neodymium lasers with high energy and output beam quality
Science.gov (United States)
Kabanov, Vladimir V.; Bezyazychnaya, Tatiana V.; Bogdanovich, Maxim V.; Grigor'ev, Alexandr V.; Lebiadok, Yahor V.; Lepchenkov, Kirill V.; Ryabtsev, Andrew G.; Ryabtsev, Gennadii I.; Shchemelev, Maxim A.
2013-05-01
Physical and fabrication peculiarities which provide the high output energy and beam quality for the diode pumped erbium glass and Nd:YAG lasers are considered. Developed design approach allow to make passively Q-switched erbium glass eye-safe portable laser sources with output energy 8 - 12 mJ (output pulse duration is less than 25 ns, pulse repetition rate up to 5 Hz) and beam quality M2 less than 1.3. To reach these values the erbium laser pump unit parameters were optimized also. Namely, for the powerful laser diode arrays the optimal near-field fill-factor, output mirror reflectivity and heterostructure properties were determined. Construction of advanced diode and solid-state lasers as well as the optical properties of the active element and the pump unit make possible the lasing within a rather wide temperature interval (e.g. from minus forty till plus sixty Celsius degree) without application of water-based chillers. The transversally pumped Nd:YAG laser output beam uniformity was investigated depending on the active element (AE) pump conditions. In particular, to enhance the pump uniformity within AE volume, a special layer which practically doesn't absorb the pump radiation but effectively scatters the pump and lasing beams, was used. Application of such layer results in amplified spontaneous emission suppression and improvement of the laser output beam uniformity. The carried out investigations allow us to fabricate the solid-state Nd:YAG lasers (1064 nm) with the output energy up to 420 mJ at the pulse repetition rate up to 30 Hz and the output energy up to 100 mJ at the pulse repetition rate of of 100 Hz. Also the laser sources with following characteristics: 35 mJ, 30 Hz (266 nm); 60 mJ, 30 Hz (355 nm); 100 mJ, 30 Hz (532 nm) were manufactured on the base of the developed Nd:YAG quantrons.
8. A 1J LD pumped Nd:YAG pulsed laser system
Science.gov (United States)
Yi, Xue-bin; Wang, Bin; Yang, Feng; Li, Jing; Liu, Ya-Ping; Li, Hui-Jun; Wang, Yu; Chen, Ren
2017-11-01
A 1J LD pumped Nd;YAG pulsed laser was designed. The laser uses an oscillation and two-staged amplification structure, and applies diode bar integrated array as side-pump. The TEC temperature control device combing liquid cooling system is organized to control the temperature of the laser system. This study also analyzed the theoretical threshold of working material, the effect of thermal lens and the basic principle of laser amplification. The results showed that the laser system can achieve 1J, 25Hz pulse laser output, and the laser pulse can be output at two width: 6-7ns and 10ns, respectively, and the original beam angle is 1.2mrad. The laser system is characterized by small size, light weight, as well as good stability, which make it being applied in varied fields such as photovoltaic radar platform and etc
9. Efficient laser performance of a cryogenic Yb:YAG laser pumped by fiber coupled 940 and 969 nm laser diodes
Czech Academy of Sciences Publication Activity Database
Jambunathan, Venkatesan; Miura, Taisuke; Těsnohlídková, L.; Lucianetti, Antonio; Mocek, Tomáš
2015-01-01
Roč. 12, č. 1 (2015), "015002-1"-"015002-6" ISSN 1612-2011 R&D Projects: GA MŠk ED2.1.00/01.0027; GA MŠk EE2.3.20.0143; GA ČR GA14-01660S Grant - others:HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : cryogenic laser s * absorption * bandwidth * emission cross-section * absorption cross-section * diode pumping Subject RIV: BH - Optics, Masers, Laser s Impact factor: 2.391, year: 2015
10. 1-kilowatt CW all-fiber laser oscillator pumped with wavelength-beam-combined diode stacks.
Science.gov (United States)
Xiao, Y; Brunet, F; Kanskar, M; Faucher, M; Wetter, A; Holehouse, N
2012-01-30
We have demonstrated a monolithic cladding-pumped ytterbium-doped single all-fiber laser oscillator generating 1 kW of CW signal power at 1080 nm with 71% slope efficiency and near diffraction-limited beam quality. Fiber components were highly integrated on "spliceless" passive fibers to promote laser efficiency and alleviate non-linear effects. The laser was pumped through a 7:1 pump combiner with seven 200-W 91x nm fiber-pigtailed wavelength-beam-combined diode-stack modules. The signal power of such a single all-fiber laser oscillator showed no evidence of roll-over, and the highest output was limited only by available pump power.
11. High Speed Pump-Probe Apparatus for Observation of Transitional Effects in Ultrafast Laser Micromachining Processes
Directory of Open Access Journals (Sweden)
Ilya Alexeev
2015-12-01
Full Text Available A pump-probe experimental approach has been shown to be a very efficient tool for the observation and analysis of various laser matter interaction effects. In those setups, synchronized laser pulses are used to create an event (pump and to simultaneously observe it (probe. In general, the physical effects that can be investigated with such an apparatus are restricted by the temporal resolution of the probe pulse and the observation window. The latter can be greatly extended by adjusting the pump-probe time delay under the assumption that the interaction process remains fairly reproducible. Unfortunately, this assumption becomes invalid in the case of high-repetition-rate ultrafast laser material processing, where the irradiation history strongly affects the ongoing interaction process. In this contribution, the authors present an extension of the pump-probe setup that allows to investigate transitional and dynamic effects present during ultrafast laser machining performed at high pulse repetition frequencies.
12. Solar-pumped 80 W laser irradiated by a Fresnel lens.
Science.gov (United States)
Ohkubo, Tomomasa; Yabe, Takashi; Yoshida, Kunio; Uchida, Shigeaki; Funatsu, Takayuki; Bagheri, Behgol; Oishi, Takehiro; Daito, Kazuya; Ishioka, Manabu; Nakayama, Yuichirou; Yasunaga, Norihito; Kido, Kouichirou; Sato, Yuji; Baasandash, Choijil; Kato, Kiyoshi; Yanagitani, Takagimi; Okamoto, Yoshiaki
2009-01-15
A solar-pumped 100 W class laser that features high efficiency and low cost owing to the use of a Fresnel lens and a chromium codoped neodymium YAG ceramic laser medium was developed. A laser output of about 80 W was achieved with combination of a 4 m(2) Fresnel lens and a pumping cavity as a secondary power concentrator. This output corresponds to 4.3% of conversion efficiency from solar power into laser, and the maximum output from a unit area of Fresnel lens was 20 W/m(2), which is 2.8 times larger than previous results with mirror-type concentrator.
13. A Q-switched Ho:YAG laser with double anti-misalignment corner cubes pumped by a diode-pumped Tm:YLF laser
Science.gov (United States)
Wang, Y. P.; Dai, T. Y.; Wu, J.; Ju, Y. L.; Yao, B. Q.
2018-06-01
We report the acousto-optically Q-switched Ho:YAG laser with double anti-misalignment corner cubes pumped by a diode-pumped Tm:YLF laser. In the continuous-wave operation of Ho:YAG laser, the maximum s-polarized output power of 3.2 W at 2090.3 nm was obtained under the absorbed pump power of 12.9 W by rotating the fast axis of quarter-wave plate to change the output transmission of laser cavity. The corresponding optical-to-optical conversion efficiency was 24.8% and the slope efficiency was 55.7%. When one of the corner cubes was rotated to 11.8° around vertical direction or 6.7° around horizontal direction, the laser could still operate stably. For the Q-switched operation, the pulse energy of Ho:YAG laser was 9.9 mJ with a pulse width of 53 ns at the repetition rate of 100 Hz, resulting in a peak power of 186.8 kW. The beam quality factor M2 of Ho:YAG laser was 1.3.
14. Comparative study of diode-pumped alkali vapor laser and exciplex-pumped alkali laser systems and selection principal of parameters
Science.gov (United States)
Huang, Wei; Tan, Rongqing; Li, Zhiyong; Han, Gaoce; Li, Hui
2017-03-01
A theoretical model based on common pump structure is proposed to analyze the output characteristics of a diode-pumped alkali vapor laser (DPAL) and XPAL (exciplex-pumped alkali laser). Cs-DPAL and Cs-Ar XPAL systems are used as examples. The model predicts that an optical-to-optical efficiency approaching 80% can be achieved for continuous-wave four- and five-level XPAL systems with broadband pumping, which is several times the pumped linewidth for DPAL. Operation parameters including pumped intensity, temperature, cell's length, mixed gas concentration, pumped linewidth, and output coupler are analyzed for DPAL and XPAL systems based on the kinetic model. In addition, the predictions of selection principal of temperature and cell's length are also presented. The concept of the equivalent "alkali areal density" is proposed. The result shows that the output characteristics with the same alkali areal density but different temperatures turn out to be equal for either the DPAL or the XPAL system. It is the areal density that reflects the potential of DPAL or XPAL systems directly. A more detailed analysis of similar influences of cavity parameters with the same areal density is also presented.
15. Efficient diode-side-pumped Nd:YVO4 slab laser in different generation regimes
International Nuclear Information System (INIS)
Zinov'ev, A P; Antipov, Oleg L; Novikov, A A
2009-01-01
A diode-side-pumped Nd:YVO 4 slab laser with the grazing-incidence bounce geometry of the cavity is studied experimentally. Upon continuous pumping different lasing regimes are realised, namely, cw, passive and active Q-switching and passive mode-locking. The resonator parameters are optimised to achieve the maximum cw output power (∼17 W) and high-quality beam (M 2 ∼ 1.3). (lasers)
16. Study of mode locking in a microwave-pumped diode laser close to the generation threshold
International Nuclear Information System (INIS)
Bagaev, Sergei N; Zakharyash, Valerii F; Kashirsky, Aleksandr V; Klementyev, Vasilii M; Kuznetsov, Sergei A; Pivtsov, V S
2004-01-01
Active mode locking is studied in a diode laser with a three-mirror resonator upon the microwave modulation of the pump current. The mode-locking region with the minimal width of the spectrum of intermode beats is found, when the microwave frequency is close to the intermode frequency of an external resonator. This region is shown to be located close to the threshold pump current. (lasers, active media)
17. Microsecond pulsed optical parametric oscillator pumped by a Q-switched fiber laser
NARCIS (Netherlands)
Klein, M.E.; Adel, P.; Auerbach, M.; Fallnich, C.; Gross, P.; Boller, Klaus J.
2003-01-01
We report on what is to our knowledge the first optical parametric oscillator (OPO) pumped by microsecond pulses from a wavelength-tunable solid-state laser. The singly resonant OPO (SRO) is based on a periodically poled LiNbO3 crystal and pumped with 2.1-ms-long pulses from an actively Q-switched
18. Solid state pump lasers with high power and high repetition rate
International Nuclear Information System (INIS)
Oba, Masaki; Kato, Masaaki; Arisawa, Takashi
1995-01-01
We built a laser diode pumped solid state green laser (LDPSSGL) rated at high repetition rate. Two laser heads are placed in one cavity with a rotator in between to design to avoid thermal lensing and thermal birefringence effect. Although average green laser power higher than 10 W was obtained at 1 kHz repetition rate with pulse width of 20-30 nsec, the beam quality was so much deteriorated that energy efficiency was as low as 2 %. Learning from this experience that high power oscillator causes a lot of thermal distortion not only in the laser rod but also in the Q-switch device, we proceeded to built a oscillator/amplifier system. A low power oscillator has a slab type crystal in the cavity. As a result spatial distribution of laser power was extremely improved. As we expect that the high repetition rate solid state laser should be CW operated Q-switch type laser from the view point of lifetime of diode lasers, a conventional arc lamp pumped CW Q-switch green YAG laser of which the repetition rate is changeable from 1 kHz to 5 kHz and the pulse width is 250-570 nsec was also tested to obtain pumping characteristics of a dye laser as a function of power, pulse width etc., and dye laser pulse width of 100-130 nsec were obtained. (author)
19. Optimisation of the parameters of a pump chamber for solid-state lasers with diode pumping by the optical boiler method
Energy Technology Data Exchange (ETDEWEB)
Kiyko, V V; Kislov, V I; Ofitserov, E N; Suzdal' tsev, A G [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
2015-06-30
A pump chamber of the optical boiler type for solid-state lasers with transverse laser diode pumping is studied theoretically and experimentally. The pump chamber parameters are optimised using the geometrical optics approximation for the pump radiation. According to calculations, the integral absorption coefficient of the active element at a wavelength of 808 nm is 0.75 – 0.8 and the relative inhomogeneity of the pump radiation distribution over the active element volume is 17% – 19%. The developed pump chamber was used in a Nd:YAG laser. The maximum cw output power at a wavelength of 1064 nm was ∼480 W at the optical efficiency up to 19.6%, which agrees with theoretical estimates. (lasers)
20. Slow modes in spin hydrodynamics of 3He-B
International Nuclear Information System (INIS)
Golo, V.L.; Kats, E.I.
1986-01-01
We study nonlinear interaction between sound and spin modes with the view of finding a means for detecting second sound pumped in a sample of 3 He-B. We find that the interaction could be tangible for second sound and spin-textual waves which are long wavelength spatial modulations of the WP mode of magnetic ringing. We show that within a thin layer close to the loudspeaker second sound generates the dephasing delta psi of the spin precession. We suggest that the mode of the w-oscillations could be detected with the technique for the propagating magnetic disturbance. Our numerical estimates indicate that in te temperature and pressure region 1 - T/Tsub(c) approximately equal to 0.01 and p=21.7 bar, and the frequency and power of second sound of order 100 Hz and 10 -3 erg/s, the dephasing of the spin precession may amount to 0.1 rad, and result in a swinging of the precession axis w
1. 2.4 μm diode-pumped Dy2+:CaF2 laser
Science.gov (United States)
Švejkar, Richard; Papashvili, Alexander G.; Šulc, Jan; Němec, Michal; Jelínková, Helena; Doroshenko, Maxim E.; Batygov, Sergei H.; Osiko, Vyacheslav V.
2018-01-01
In this work, a cryogenic cooled, longitudinal diode-pumped Dy2+ :CaF2 laser was investigated for the first time. The temperature dependence of the spectroscopy and the laser properties of Dy2+ :CaF2 are presented. The tested Dy2+ :CaF2 crystal was a longitudinal pump in a near-IR region (926 nm) by laser diode radiation. The maximal mean output power and slope efficiency at 78 K during the pulse regime of the laser were 57.5 mW and 7%, respectively. Furthermore, the CW regime was successfully tested and a maximum output power of 0.37 W was obtained for the absorbed pumping power 5.7 W. The emission laser wavelength was 2367 nm.
2. Mode structure of delay-coupled semiconductor lasers: influence of the pump current
International Nuclear Information System (INIS)
Erzgraeber, Hartmut; Krauskopf, Bernd; Lenstra, Daan
2005-01-01
We consider two identical, mutually delay-coupled semiconductor lasers and show that their compound laser modes (CLMs)-the basic continuous wave solutions-depend rather sensitively on the pump current of the lasers. Specifically, we show with figures and accompanying animations how the underlying CLM structure and the associated locking region, where both lasers operate stably with the same frequency, change as a function of the pump current. Our results provide a natural transition between rather different CLM structures that have been reported in the literature. Moreover, we demonstrate how the locking region as well as the different types of instabilities at its boundary depend on the pump current. This is of fundamental interest for the dynamics of coupled lasers and their possible application
3. Short-pulse generation in a diode-end-pumped solid-state laser
CSIR Research Space (South Africa)
Ngcobo, S
2010-09-01
Full Text Available , Development of High Average Power Picosecond Laser Systems, Opto- Electronic Devices, (2002). INTRODUCTION A Nd:YVO4 modelocked laser has been constructed using a resonator designed according to the theoretical parameters. The laser produced pulses... theoretical PQSML,th of 2.08W. Short-Pulse Generation in a Diode-End-Pumped Solid-State Laser S. Ngcobo1,2, C. Bollig1 and H. Von Bergmann2 1CSIR National Laser Centre, PO Box 395, Pretoria, 0001, South Africa 2Laser Research Center, University...
4. Pulsed and cw laser oscillations in LiF:F-2 color center crystal under laser diode pumping.
Science.gov (United States)
Basiev, Tasoltan T; Vassiliev, Sergey V; Konjushkin, Vasily A; Gapontsev, Valentin P
2006-07-15
Continuous-wave laser oscillations in LiF:F-2 crystal optically pumped by a laser diode at 970 nm were demonstrated for what is believed to be the first time. The slope efficiency of 14% and conversion efficiency of 5.5% were achieved for 80 micros pump pulse duration and 5 Hz pulse repetition rate. An efficiency twice as low was measured at a 6.25 kHz pulse repetition rate (50% off-duty factor) and in cw mode of laser operation.
5. Basic studies on laser-assisted phacoemulsification using diode-pumped Er:YAG laser
Science.gov (United States)
Hausladen, Florian; Wurm, Holger; Stock, Karl
2016-03-01
The aim of this study was to determine the potential of a novel diode-pumped Er:YAG laser for phacoemulsification in basic experimental investigations. An appropriate experimental setup was created, including a translation stage for sample movement, a sample holder, a water spray for sample humidification and a surgical microscope with a CCD camera for video documentation. The analysis of the laser cuts and histological sections was done by light microscopy. As samples porcine eye lenses hardened by formalin were used. In ablation experiments with different spot diameters and radiant powers and a constant repetition rate νr = 200 Hz the maximum ablation depths of (4.346 +/- 0.044) mm have reached at (Ø = 480 μm, Φ = 24.15 W) with a maximum extend of thermal damage of (0.165 +/- 0.030) mm. The average ablation efficiency is 0.241 mm3/J. With a spot diameter of 308 μm the maximum ablation depth is (4.238 +/- 0.040) mm at 24.65 W with a mean ablation efficiency of 0.293 mm3/J. The extend of the thermally damaged region is (0.171 +/- 0.024) mm at this laser power. Using a sapphire cylinder with a diameter of 412 μm (length 38.5 mm) in direct tissue contact with water spray for sample humidification the ablation depth reaches (1.017 +/- 0.074) mm at 4.93 W and (1.840 +/- 0.092) mm at 9.87 W with a mean efficiency of 0.261 mm3/J. A thermal damage zone of (0.064 +/-0.024) mm at 9.87 W was measured. Additionally, at this high power, a progressive contamination and destruction of the cylinder end facet was observed. In conclusion, the investigations show that the diode-pumped Er:YAG laser has considerable potential for cataract surgery.
6. Spin waves at the liquid 3He-4He interface
International Nuclear Information System (INIS)
Heff, A.; Candela, D.; Edwards, D.O.; Kumar, S.
1987-01-01
The properties of various interfaces in helium and, in particular, the interface between liquid 3 He and a solution of 3 He in 4 He, may be studied using spin waves. Assuming no transverse relaxation, the boundary condition for the transverse magnetization contains one complex kinetic coefficient, b. For the normal 3 He to 3 He- 4 He interface, b is related to the 3 He quasi-particle transmission probability antiτ, which we estimate from a simple model. A calculation of the spin wave absorption spectrum for a typical geometry shows that b and antiτ may be measured by NMR. Neither b nor antiτ is greatly affected when the pure 3 He enters the A phase, but both are strongly reduced in the B phase
7. Development of a compact vertical-cavity surface-emitting laser end-pumped actively Q-switched laser for laser-induced breakdown spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Li, Shuo; Chen, Rongzhang; Nelsen, Bryan; Chen, Kevin, E-mail: [email protected] [Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Liu, Lei; Huang, Xi; Lu, Yongfeng [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)
2016-03-15
This paper reports the development of a compact and portable actively Q-switched Nd:YAG laser and its applications in laser-induced breakdown spectroscopy (LIBS). The laser was end-pumped by a vertical-cavity surface-emitting laser (VCSEL). The cavity lases at a wavelength of 1064 nm and produced pulses of 16 ns with a maximum pulse energy of 12.9 mJ. The laser exhibits a reliable performance in terms of pulse-to-pulse stability and timing jitter. The LIBS experiments were carried out using this laser on NIST standard alloy samples. Shot-to-shot LIBS signal stability, crater profile, time evolution of emission spectra, plasma electron density and temperature, and limits of detection were studied and reported in this paper. The test results demonstrate that the VCSEL-pumped solid-state laser is an effective and compact laser tool for laser remote sensing applications.
8. High energy erbium laser end-pumped by a laser diode bar array coupled to a Nonimaging Optic Concentrator
OpenAIRE
Tanguy , Eric; Feugnet , Gilles; Pocholle , Jean-Paul; Blondeau , R.; Poisson , M.A.; Duchemin , J.P.
1998-01-01
International audience; A high energy Er3+, Yb3+:glass laser end pumped by a laser diode array emitting at 980 nm coupled to a Nonimaging Optic Concentrator (NOC) is demonstrated. Energy up to 100 mJ and a 16% slope efficiency are achieved in a plano-plano laser cavity. The energy transfer coefficient from Yb3+ to Er3+ is estimated by a new method.
9. Efficient quasi-three-level Nd:YAG laser at 946 nm pumped by a tunable external cavity tapered diode laser
DEFF Research Database (Denmark)
Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Tidemand-Lichtenberg, Peter
2010-01-01
Using a tunable external cavity tapered diode laser (ECDL) pumped quasi-three-level Nd:YAG laser, a fivefold reduction in threshold and twofold increase in slope efficiency is demonstrated when compared to a traditional broad area diode laser pump source. A TEM00 power of 800 mW with 65% slope...... efficiency is obtained, the highest reported TEM00 power from any 946 nm Nd:YAG laser pumped by a single emitter diode laser pump source. A quantum efficiency of 0.85 has been estimated from experimental data using a simple quasi-three-level model. The reported value is in good agreement with published...
10. Spin-exchange and spin-destruction rates for the 3He-Na system
International Nuclear Information System (INIS)
Borel, P.I.; Soegaard, L.V.; Svendsen, W.E.; Andersen, N.
2003-01-01
Optically pumped Na is used as a spin-exchange partner to polarize 3 He. Polarizations around 20% have routinely been achieved in sealed spherical glass cells containing 3 He, N 2 , and a few droplets of Na. An optical technique has been developed to determine the Na- 3 He spin-exchange rate coefficient. By monitoring the Na spin relaxation ''in the dark,'' the average Na-Na spin-destruction cross section at 330 degree sign C is estimated to be around 5x10 -19 cm 2 . This value is 2-5 (15-30) times smaller than the previously reported values for the K-K (Rb-Rb) spin-relaxation cross section. In the temperature range 310-355 degree sign C the spin-exchange rate coefficient is found to be (6.1±0.6)x10 -20 cm 3 /s with no detectable temperature dependence. This value is in good agreement with a previous theoretical estimate reported by Walker and it is only slightly lower than the corresponding Rb- 3 He spin-exchange rate coefficient. The total Na- 3 He spin-destruction rate coefficient is, within errors, found to be the same as the Na- 3 He spin-exchange rate coefficient, thereby indicating that the maximum possible photon efficiency may approach unity for the Na- 3 He system. A technique, in which a charge-coupled device camera is used to take images of faint unquenched fluorescence light, has been utilized to allow for an instantaneous determination of the sodium number densities during the rate coefficient measurements
11. Optimization of end-pumped, actively Q-switched quasi-III-level lasers.
Science.gov (United States)
Jabczynski, Jan K; Gorajek, Lukasz; Kwiatkowski, Jacek; Kaskow, Mateusz; Zendzian, Waldemar
2011-08-15
The new model of end-pumped quasi-III-level laser considering transient pumping processes, ground-state-depletion and up-conversion effects was developed. The model consists of two parts: pumping stage and Q-switched part, which can be separated in a case of active Q-switching regime. For pumping stage the semi-analytical model was developed, enabling the calculations for final occupation of upper laser level for given pump power and duration, spatial profile of pump beam, length and dopant level of gain medium. For quasi-stationary inversion, the optimization procedure of Q-switching regime based on Lagrange multiplier technique was developed. The new approach for optimization of CW regime of quasi-three-level lasers was developed to optimize the Q-switched lasers operating with high repetition rates. Both methods of optimizations enable calculation of optimal absorbance of gain medium and output losses for given pump rate. © 2011 Optical Society of America
12. Solid-state laser pumping with a planar compound parabolic concentrator.
Science.gov (United States)
Panteli, D V; Pani, B M; Beli, L Z
1997-10-20
A novel solid-state laser-pumping scheme is proposed that combines a reflective lamp chamber and a compound parabolic concentrator (CPC) as a light guide. The CPC is made of a transparent material of high refractive index, and light is guided by the total internal reflection, with drastically reduced reflection losses. Material is chosen so that the absorption losses are minimized in the pumping wavelength range. The lamp chamber is designed with the principles of nonimaging optics, which ensures that the radiation is efficiently transferred from the lamp to the input aperture of the CPC. The pumping efficiency was first estimated theoretically, which gave us enough justification for the more accurate calculations with ray tracing. Single as well as multiple pumping cavities are discussed. New pumping geometry results in significantly increased pumping efficiency compared with conventional geometries. Also the lamp and the laser rod are separated, leading to reduced thermal load. We found that the proposed pumping method is also applicable to diode-pumped lasers.
Science.gov (United States)
Egorova, O N; Semjonov, S L; Velmiskin, V V; Yatsenko, Yu P; Sverchkov, S E; Galagan, B I; Denker, B I; Dianov, E M
2014-04-07
We present a composite optical fiber with a Er/Yb co-doped phosphate-glass core in a silica glass cladding as well as cladding pumped laser. The fabrication process, optical properties, and lasing parameters are described. The slope efficiency under 980 nm cladding pumping reached 39% with respect to the absorbed pump power and 28% with respect to the coupled pump power. Due to high doping level of the phosphate core optimal length was several times shorter than that of silica core fibers.
14. High power operation of cladding pumped holmium-doped silica fibre lasers.
Science.gov (United States)
Hemming, Alexander; Bennetts, Shayne; Simakov, Nikita; Davidson, Alan; Haub, John; Carter, Adrian
2013-02-25
We report the highest power operation of a resonantly cladding-pumped, holmium-doped silica fibre laser. The cladding pumped all-glass fibre utilises a fluorine doped glass layer to provide low loss cladding guidance of the 1.95 µm pump radiation. The operation of both single mode and large-mode area fibre lasers was demonstrated, with up to 140 W of output power achieved. A slope efficiency of 59% versus launched pump power was demonstrated. The free running emission was measured to be 2.12-2.15 µm demonstrating the potential of this architecture to address the long wavelength operation of silica based fibre lasers with high efficiency.
15. A simple equilibrium theoretical model and predictions for a continuous wave exciplex pumped alkali laser
International Nuclear Information System (INIS)
Carroll, David L; Verdeyen, Joseph T
2013-01-01
The exciplex pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapour, Ar, with and without ethane, by pumping Cs-Ar atomic collision pairs and subsequent dissociation of diatomic, electronically excited CsAr molecules (exciplexes or excimers). The blue satellites of the alkali D 2 lines provide an advantageous pathway for optically pumping atomic alkali lasers on the principal series (resonance) transitions with broad linewidth (>2 nm) semiconductor diode lasers. The development of a simple theoretical analysis of continuous-wave XPAL systems is presented along with predictions as a function of temperature and pump intensity. The model predicts that an optical-to-optical efficiency in the range of 40-50% can be achieved for XPAL.
16. Spatial modification of laser beam under the influence of Λ-type strong pump
International Nuclear Information System (INIS)
Lee, Won Kyu; Noh, Young Chul; Jeon, Jin Ho; Lee, Jai Hyung; Chang, Joon Sung
1999-01-01
The laser beam propagating through the resonant medium undergo severe deformation because of nonlinear interaction such as self-focusing, self-defocusing, etc. When strong pump beam coexists with the probe beam, propagation characteristics can be changed. We use samarium (Sm) vapor as the nonlinear medium. Probe laser is tuned around 4f 6 6s 27 F 0 -> 4f 6 ( 7 F)6s6p( 1 P 0 ) transition line of Sm (561.601 nm) and the pump laser is tuned around 4f 6 6s 27 F 1 -> 4f 6 ( 7 F)6s6p( 1 P 0 ) transition line of Sm (572.019 nm). The probe and the pump beams are Λ-type configuration. The transmission of the probe beam is changed as the intensity and the detuning of the pump beam are varied. The degree of self-focusing is also modified. (author)
17. THERMAL LENSING MEASUREMENTS IN THE ANISOTROPIC LASER CRYSTALS UNDER DIODE PUMPING
Directory of Open Access Journals (Sweden)
P. A. Loiko
2012-01-01
Full Text Available An experimental setup was developed for thermal lensing measurements in the anisotropic diode-pumped laser crystals. The studied crystal is placed into the stable two-mirror laser cavity operating at the fundamental transversal mode. The output beam radius is measured with respect to the pump intensity for different meridional planes (all these planes contain the light propagation direction. These dependencies are fitted using the ABCD matrix method in order to obtain the sensitivity factors showing the change of the optical power of thermal lens due to variation of the pump intensity. The difference of the sensitivity factors for two mutually orthogonal principal meridional planes describes the thermal lens astigmatism degree. By means of this approach, thermal lensing was characterized in the diode-pumped monoclinic Np-cut Nd:KGd(WO42 laser crystal at the wavelength of 1.067 μm for light polarization E || Nm.
18. A Phase-Controlled Optical Parametric Amplifier Pumped by Two Phase-Distorted Laser Beams
International Nuclear Information System (INIS)
Hong-Yan, Ren; Lie-Jia, Qian; Peng, Yuan; He-Yuan, Zhu; Dian-Yuan, Fan
2010-01-01
We theoretically study the phase characteristic of optical parametric amplification (OPA) or chirped pulse OPA (OPCPA) pumped by two phase-distorted laser beams. In the two-beam-pumped optical parametric amplification (TBOPA), due to spatial walk-off, both of the pump phase distortions will be partly transferred to signal in a single crystal so as to degrade the signal beam-quality, which will be more serious in high-energy OPCPA. An OPA configuration with a walkoff-compensated crystal pair is demonstrated for reducing the signal phase distortion experienced in the first stage and ensuring the signal phase independent of two pump phase distortions through the second crystal, hence maintaining the signal beam-quality. Such a TBOPA is similar to the conventional quantum laser amplifier by means of eliminating its sensitivity to the phase and number of the pump beams
19. Frequency-doubled DBR-tapered diode laser for direct pumping of Ti:sapphire lasers generating sub-20 fs pulses
DEFF Research Database (Denmark)
Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika
2011-01-01
For the first time a single-pass frequency doubled DBR-tapered diode laser suitable for pumping Ti:sapphire lasers generating ultrashort pulses is demonstrated. The maximum output powers achieved when pumping the Ti:sapphire laser are 110 mW (CW) and 82 mW (mode-locked) respectively at 1.2 W...... of pump power. This corresponds to a reduction in optical conversion efficiencies to 75% of the values achieved with a commercial diode pumped solid-state laser. However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2....... The optical spectrum emitted by the Ti:sapphire laser when pumped with our diode laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20 fs can therefore be expected....
20. Frequency-doubled DBR-tapered diode laser for direct pumping of Ti:sapphire lasers generating sub-20 fs pulses.
Science.gov (United States)
Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika; Le, Tuan; Stingl, Andreas; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael
2011-06-20
For the first time a single-pass frequency doubled DBR-tapered diode laser suitable for pumping Ti:sapphire lasers generating ultrashort pulses is demonstrated. The maximum output powers achieved when pumping the Ti:sapphire laser are 110 mW (CW) and 82 mW (mode-locked) respectively at 1.2 W of pump power. This corresponds to a reduction in optical conversion efficiencies to 75% of the values achieved with a commercial diode pumped solid-state laser. However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser when pumped with our diode laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20 fs can therefore be expected.
1. Discrete excitation of mode pulses using a diode-pumped solid-state digital laser
CSIR Research Space (South Africa)
Ngcobo, Sandile
2016-02-01
Full Text Available In this paper, we experimentally demonstrate novel method of generating discrete excitation of on-demand Lagaurre-Gaussian (LG) mode pulses, in a diode pumped solid-state digital laser. The digital laser comprises of an intra-cavity spatial light...
2. 5.4W cladding-pumped Nd:YAG silica fiber laser
OpenAIRE
Yoo, S.; Webb, A.S.; Standish, R.J.; May-Smith, T.C.; Sahu, J.K.
2012-01-01
We report on the spectroscopy and laser characteristics of Nd-doped fiber, fabricated by rod-in-tube from Nd:YAG as a core material with silica cladding. A cladding-pumped CW laser operation at 1058nm with 52% slope-efficiency is demonstrated.
3. Cladding-pumped Yb-doped fiber laser with vortex output beam
OpenAIRE
Lin, Di; Clarkson, William
2015-01-01
A simple technique for selectively generating a donut-shaped LP11 mode with vortex phase front in a cladding-pumped ytterbium-doped fiber laser is reported. The laser yielded 36W of output with a slope efficiency of 74%.
4. The future of diode pumped solid state lasers and their applicability to the automotive industry
Science.gov (United States)
Solarz, R.; Beach, R.; Hackel, L.
1994-03-01
The largest commercial application of high power lasers is for cutting and welding. Their ability to increase productivity by introducing processing flexibility and integrated automation into the fabrication process is well demonstrated. This paper addresses the potential importance of recent developments in laser technology to further impact their use within the automotive industry. The laser technology we will concentrate upon is diode laser technology and diode-pumped solid-state laser technology. We will review present device performance and cost and make projections for the future in these areas. Semiconductor laser arrays have matured dramatically over the last several years. They are lasers of unparalleled efficiency (greater than 50%), reliability (greater than 10,000 hours of continuous operation), and offer the potential of dramatic cost reductions (less than a dollar per watt). They can be used directly in many applications or can be used to pump solid-state lasers. When used as solid-state laser pump arrays, they simultaneously improve overall laser efficiency, reduce size, and improve reliability.
5. Diode-pumped mode-locked femtosecond Tm:CLNGG disordered crystal laser.
Science.gov (United States)
Ma, J; Xie, G Q; Gao, W L; Yuan, P; Qian, L J; Yu, H H; Zhang, H J; Wang, J Y
2012-04-15
A diode-end-pumped passively mode-locked femtosecond Tm-doped calcium lithium niobium gallium garnet (Tm:CLNGG) disordered crystal laser was demonstrated for the first time to our knowledge. With a 790 nm laser diode pumping, stable CW mode-locking operation was obtained by using a semiconductor saturable absorber mirror. The disordered crystal laser generated mode-locked pulses as short as 479 fs, with an average output power of 288 mW, and repetition rate of 99 MHz in 2 μm spectral region. © 2012 Optical Society of America
6. Amplified spontaneous emission of an end-pumped cesium vapor laser
International Nuclear Information System (INIS)
An, Guofei; Wang, You; Cai, He; Han, Juhong; Wang, Shunyan; Rong, Kepeng; Yu, Hang; Xue, Liangping; Zhang, Wei; Wang, Hongyuan; Zhou, Jie
2017-01-01
Diode pumped alkali lasers (DPALs) provide a significant potential for construction of high-powered lasers. A series of models have been established to analyze the DPAL’s kinetic process and most of them are based on the algorithms in which the amplified spontaneous emission (ASE) effect has not been considered. However, ASE is harmful in realization of a high-powered DPAL since the gain is very high. Usually, ASE becomes serious when the volume of the gain medium is large and the pump power is high. Basically, the conclusions we obtained in this study can be extended to other kinds of laser configurations. (paper)
7. A Simple Approach for Enhancing the Output Performance of Solar-Pumped Solid-State Lasers
Directory of Open Access Journals (Sweden)
Dawei Liang
2009-01-01
Full Text Available A simple truncated fused silica elliptical cavity is proposed to enhance the output performance of solar-pumped solid-state lasers. The imaging property of the truncated elliptical cavity ensures an enhanced absorption distribution within an Nd:YAG rod. Optimum pumping parameters are found through ZEMAX nonsequential ray-tracing and LASCAD laser cavity analyses. Compared with the output laser performance of a 3D-compound parabolic concentrator-2D-compound parabolic concentrator (3D-CPC-2D-CPC cavity, the truncated cavity provides 11% more multimode and 72.7% more TEM00 laser powers. A laser beam of high beam quality can be produced efficiently. The standard tracking error for multimode laser power is also reduced to only 4.0% by the truncated cavity.
8. Pulse forming networks for fast pumping of high power electron-beam-controlled CO2 lasers
International Nuclear Information System (INIS)
Riepe, K.B.
1975-01-01
The transverse electric discharge is a widely used technique for pumping CO 2 lasers at high pressures for the generation, simply and efficiently, of very high power laser pulses. The development of the electron-beam-controlled discharge has allowed the application of the transverse discharge to large aperture, very high energy systems. LASL is now in the process of assembly and checkout of a CO 2 laser which is designed to generate a one nanosecond pulse containing 10 kilojoules, for use in laser fusion experiments. The front end of this laser consists of a set of preamplifiers and a mode locked oscillator with electro-optic single pulse switchout. The final amplifier stage consists of four parallel modules, each one consisting of a two-sided electron gun, and two 35 x 35 x 200 cm gas pumping regions operating at a pressure of 1800 torr with a 3/ 1 / 4 /1 (He/N 2 /CO 2 ) laser mix. (auth)
9. Spherical distribution structure of the semiconductor laser diode stack for pumping
International Nuclear Information System (INIS)
Zhao Tianzhuo; Yu Jin; Liu Yang; Zhang Xue; Ma Yunfeng; Fan Zhongwei
2011-01-01
A semiconductor laser diode stack is used for pumping and 8 semiconductor laser diode arrays of the stack are put on a sphere, and the output of every bar is specially off-axis compressed to realize high coupling efficiency. The output beam of this semiconductor laser diode stack is shaped by a hollow duct to the laser active medium. The efficiency of the hollow light pipe, which is used for semiconductor laser diode stack coupling, is analyzed by geometric optics and ray tracing. Geometric optics analysis diagnoses the reasons for coupling loss and guides the design of the structure. Ray tracing analyzes the relation between the structural parameters and the output characteristics of this pumping system, and guides parameter optimization. Simulation and analysis results show that putting the semiconductor laser diode arrays on a spherical surface can increase coupling efficiency, reduce the optimum duct length and improve the output energy field distribution. (semiconductor devices)
10. Intensity Noise Transfer Through a Diode-pumped Titanium Sapphire Laser System
DEFF Research Database (Denmark)
Tawfieq, Mahmoud; Hansen, Anders Kragh; Jensen, Ole Bjarlin
2017-01-01
higher RIN than a setup with only a single nonlinear crystal. The Ti:S is shown to have a cut-off frequency around 500 kHz, which means that noise structures of the pump laser above this frequency are strongly suppressed. Finally, the majority of the Ti:S noise seems to originate from the laser itself......In this paper, we investigate the noise performance and transfer in a titanium sapphire (Ti:S) laser system. This system consists of a DBR tapered diode laser, which is frequency doubled in two cascaded nonlinear crystals and used to pump the Ti:S laser oscillator. This investigation includes...... electrical noise characterizations of the utilized power supplies, the optical noise of the fundamental light, the second harmonic light, and finally the optical noise of the femtosecond pulses emitted by the Ti:S laser. Noise features originating from the electric power supply are evident throughout...
11. Resonantly diode-pumped continuous-wave and Q-switched Er:YAG laser at 1645 nm.
Science.gov (United States)
Chang, N W H; Simakov, N; Hosken, D J; Munch, J; Ottaway, D J; Veitch, P J
2010-06-21
We describe an efficient Er:YAG laser that is resonantly pumped using continuous-wave (CW) laser diodes at 1470 nm. For CW lasing, it emits 6.1 W at 1645 nm with a slope efficiency of 36%, the highest efficiency reported for an Er:YAG laser that is pumped in this manner. In Q-switched operation, the laser produces diffraction-limited pulses with an average power of 2.5 W at 2 kHz PRF. To our knowledge this is the first Q-switched Er:YAG laser resonantly pumped by CW laser diodes.
12. A High-Energy, 100 Hz, Picosecond Laser for OPCPA Pumping
Directory of Open Access Journals (Sweden)
Hongpeng Su
2017-09-01
Full Text Available A high-energy diode-pumped picosecond laser system centered at 1064 nm for optical parametric chirped pulse amplifier (OPCPA pumping was demonstrated. The laser system was based on a master oscillator power amplifier configuration, which contained an Nd:YVO4 mode-locked seed laser, an LD-pumped Nd:YAG regenerative amplifier, and two double-pass amplifiers. A reflecting volume Bragg grating with a 0.1 nm reflective bandwidth was used in the regenerative amplifier for spectrum narrowing and pulse broadening to suit the pulse duration of the optical parametric amplifier (OPA process. Laser pulses with an energy of 316.5 mJ and a pulse duration of 50 ps were obtained at a 100 Hz repetition rate. A top-hat beam distribution and a 0.53% energy stability (RMS were achieved in this system.
13. Modeling of a diode-pumped thin-disk cesium vapor laser
Science.gov (United States)
An, Guofei; Cai, He; Liu, Xiaoxu; Han, Juhong; Zhang, Wei; Wang, Hongyuan; Wang, You
2018-03-01
A diode pumped alkali laser (DPAL) provides a significant potential for construction of high-powered lasers. Until now, a series of models have been established to analyze the kinetic process and most of them are based on the end-pumped alkali laser system in which the vapor cell are usually cylindrical and cuboid. In this paper, a mathematic model is constructed to investigate the kinetic processes of a diode pumped thin-disk cesium vapor laser, in which the cesium vapor and the buffer gases are beforehand filled in a sealed glass cell with a thin-disk structure. We systemically study the influences of the cell temperature and cell thickness on the output features of a thin-disk DPAL. Further, we study the thin-disk DPAL with the W-shaped resonator and multiple-disk configuration. To the best of our knowledge, there have not been any similar reports so far.
14. Closely spaced mirror pair for reshaping and homogenizing pump beams in laser amplifiers
International Nuclear Information System (INIS)
Bass, I.L.
1992-12-01
Channeling a laser beam by multiple reflections between two closely-spaced, parallel or nearly parallel mirrors, serves to reshape and homogenize the beam at the output gap between the mirrors. Application of this device to improve the spatial overlap of a copper laser pump beam with the signal beam in a dye laser amplifier is described. This technique has been applied to the AVLIS program at the Lawrence Livermore National Laboratory
15. Diode-pumped Tm:YAP/YVO4 intracavity Raman laser
International Nuclear Information System (INIS)
Zhao, Jiaqun; Zhou, Xiaofeng; Wang, Guodong; Cheng, Ping; Xu, Feng
2017-01-01
The laser performance based on YVO 4 Raman conversion in a diode-pumped actively Q-switched Tm:YAP laser is demonstrated for the first time. With an incident diode power of 10.9 W and a pulse repetition rate of 1 kHz, the average output powers for the first Stokes laser at 2.4 μm is about 270 mW. (paper)
16. A diode-end-pumped Nd:GYSGG continuous wave laser at 1104 nm
International Nuclear Information System (INIS)
Shen, B J; Kang, H X; Zhang, C G; Chen, P; Gao, R L; Liang, J; Gao, H J; Zhang, Q L; Sun, D L; Yin, S T; Luo, J Q
2013-01-01
The continuous wave (CW) laser performance of Nd:GYSGG at 1104 nm is investigated for the first time, to our knowledge. A CW laser output power of 4.7 W is obtained when the pump power of the 808 nm fiber coupled laser diode is 19.1 W, corresponding to a conversion efficiency of 24.6% and slope efficiency of 37%. (paper)
17. Observation of flow dissipation in 3He-B
International Nuclear Information System (INIS)
Eisenstein, J.P.; Packard, R.E.
1982-01-01
Anomalous dissipation is observed in 3 He-B flowing in a U-tube device. The dissipation is of unknown origin and persists to the lowest measured velocity. The position of this result in the framework of other 3 He-B flow experiments is discussed
18. Development of data acquisition system for CSNS 3He detector
International Nuclear Information System (INIS)
Zhao Dongxu; Zhang Hongyu
2012-01-01
This paper introduces the research and development of data acquisition system of CSNS 3 He detector prototype. This system provides high performance data acquisition capability of CSNS 3 He detector, as well as several performance tests of electronics prototype. This data acquisition system establishes foundation for the later data acquisition development. (authors)
19. The Cosmic Abundance of 3He: Green Bank Telescope Observations
Science.gov (United States)
Balser, Dana; Bania, Thomas
2018-01-01
The Big Bang theory for the origin of the Universe predicts that during the first ~1,000 seconds significant amounts of the light elements (2H, 3He, 4He, and 7Li) were produced. Many generations of stellar evolution in the Galaxy modifies these primordial abundances. Observations of the 3He+ hyperfine transition in Galactic HII regions reveals a 3He/H abundance ratio that is constant with Galactocentric radius to within the uncertainties, and is consistent with the primordial value as determined from cosmic microwave background experiments (e.g., WMAP). This "3He Plateau" indicates that the net production and destruction of 3He in stars is approximately zero. Recent stellar evolution models that include thermohaline mixing, however, predict that 3He/H abundance ratios should slightly decrease with Galactocentric radius, or in places in the Galaxy with lower star formation rates. Here we discuss sensitive Green Bank Telescope (GBT) observations of 3He+ at 3.46 cm in a subset of our HII region sample. We develop HII region models and derive accurate 3He/H abundance ratios to better constrain these new stellar evolution models.
20. Superfluidity of a dilute 3He-4He solution
International Nuclear Information System (INIS)
Soda, Toshio
1993-01-01
The interaction between two 3 He atoms is calculated by taking into account the backflow effect of 3 He by the 4 He in the 3 He- 4 He mixture. The effect contributes solely to the P wave part of the interaction. The repulsive S wave part of the contact interaction contributes to the exchange interaction between the 3 He atoms, while the direct one phonon exchange interaction contributes both to the S and P wave attractive interactions. The overall contribution to the attractive interaction is dominated by the P wave part and the superfluidity in the P wave is more predominant than in the S wave for the 5 % dilute 3 He- 4 He solution, and vice versa for the 1.3 % solution. (author)
1. Determination of the π3He3H coupling constant
International Nuclear Information System (INIS)
Nichitiu, F.; Sapozhnikov, M.G.
1977-01-01
Despersion relations for the real part of the antisymmetric amplitude of the π +-3 He scattering have been used in order to determine the π 3 He 3 H coupling constant. The coupling constant value determined by this method is larger than the elementary pion-nucleon coupling constant, but is in good agreement with the value obtained by another method. The obtained value is f 2 sub(π 3 He 3 H) = 0.12+-0.01. Shown is the importance of using the Coulomb corrections for dispersion relation calculations because the value of π 3 He 3 H coupling constant obtained with corrected total cross sections is larger by about 0.014 than the one obtained without these corrections. The best energy ranges for future π 3 He experiments are commented
2. Improved performance of high average power semiconductor arrays for applications in diode pumped solid state lasers
International Nuclear Information System (INIS)
Beach, R.; Emanuel, M.; Benett, W.; Freitas, B.; Ciarlo, D.; Carlson, N.; Sutton, S.; Skidmore, J.; Solarz, R.
1994-01-01
The average power performance capability of semiconductor diode laser arrays has improved dramatically over the past several years. These performance improvements, combined with cost reductions pursued by LLNL and others in the fabrication and packaging of diode lasers, have continued to reduce the price per average watt of laser diode radiation. Presently, we are at the point where the manufacturers of commercial high average power solid state laser systems used in material processing applications can now seriously consider the replacement of their flashlamp pumps with laser diode pump sources. Additionally, a low cost technique developed and demonstrated at LLNL for optically conditioning the output radiation of diode laser arrays has enabled a new and scalable average power diode-end-pumping architecture that can be simply implemented in diode pumped solid state laser systems (DPSSL's). This development allows the high average power DPSSL designer to look beyond the Nd ion for the first time. Along with high average power DPSSL's which are appropriate for material processing applications, low and intermediate average power DPSSL's are now realizable at low enough costs to be attractive for use in many medical, electronic, and lithographic applications
3. High-fidelity modelling of an exciplex pumped alkali laser with radiative transport
International Nuclear Information System (INIS)
Palla, Andrew D; Carroll, David L; Verdeyen, Joseph T; Heaven, Michael C
2011-01-01
The exciplex-pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapour, Ar, and ethane by pumping Cs-Ar atomic collision pairs and subsequent dissociation of diatomic, electronically excited CsAr molecules (exciplexes or excimers). Because of the addition of atomic collision pairs and exciplex states, modelling of the XPAL system is far more complicated than the modelling of the classic diode-pumped alkali laser (DPAL). In this paper, we discuss BLAZE-V time-dependent multi-dimensional modelling of this new laser system including radiative transport and parasitic loss effects. A two-dimensional, time-dependent baseline simulation of a pulsed XPAL is presented and compared to data. Good agreement is achieved on a laser pulse full width at half-maximum and laser pulse rise time. Parametric simulations of pulsed XPAL system configurations similar to that of the baseline case, given both four- and five-level laser operation, are presented in which good agreement is obtained with outcoupled laser energy as a function of absorbed pump energy data. The potential impact of parasitic losses on modelled system configurations is discussed.
4. High-fidelity modelling of an exciplex pumped alkali laser with radiative transport
Energy Technology Data Exchange (ETDEWEB)
Palla, Andrew D; Carroll, David L; Verdeyen, Joseph T [CU Aerospace, Champaign, IL 61820 (United States); Heaven, Michael C, E-mail: [email protected] [Department of Chemistry, Emory University, Atlanta, GA 30322 (United States)
2011-07-14
The exciplex-pumped alkali laser (XPAL) system has been demonstrated in mixtures of Cs vapour, Ar, and ethane by pumping Cs-Ar atomic collision pairs and subsequent dissociation of diatomic, electronically excited CsAr molecules (exciplexes or excimers). Because of the addition of atomic collision pairs and exciplex states, modelling of the XPAL system is far more complicated than the modelling of the classic diode-pumped alkali laser (DPAL). In this paper, we discuss BLAZE-V time-dependent multi-dimensional modelling of this new laser system including radiative transport and parasitic loss effects. A two-dimensional, time-dependent baseline simulation of a pulsed XPAL is presented and compared to data. Good agreement is achieved on a laser pulse full width at half-maximum and laser pulse rise time. Parametric simulations of pulsed XPAL system configurations similar to that of the baseline case, given both four- and five-level laser operation, are presented in which good agreement is obtained with outcoupled laser energy as a function of absorbed pump energy data. The potential impact of parasitic losses on modelled system configurations is discussed.
5. PERFORMANCE OPTIMIZATION OF THE DIODE-PUMPED SOLID-STATE LASER FOR SPACE APPLICATIONS
Directory of Open Access Journals (Sweden)
D. A. Arkhipov
2015-11-01
Full Text Available Subject of Research. Thermophysical and optical techniques of parameter regulation for diode pumped solid-state laser are studied as applied to space laser communication and laser ranging lines. Methods. The investigations are carried out on the base of the original design of diode pumped solid-state laser module that includes the following: Nd:YAG slab element, diode pumped by 400W QCW produced by NORTHROP GRUMMAN; two-pass unstable resonator with rotation of the laser beam aperture about its axis through 1800; the output mirror of the resonator with a variable reflection coefficient; hyperthermal conductive plates for thermal stabilization of the laser diode generation modes. The presence of thermal conductive plates excludes conventional running water systems applied as cooling systems for solid-state laser components. The diodes temperature stabilization is achieved by applying the algorithm of pulse-width modulation of power of auxiliary electric heaters. To compensate for non-stationary thermal distortions of the slab refractive index, the laser resonator scheme comprises a prism reflector with an apex angle of 1200. Narrow sides of the prism are covered with reflective coating, and its wide side is sprayed with antireflection coating. The beam aperture is turned around its axis through 1800 because of triple reflection of the beam inside the prism. The turning procedure leads to compensating for the output beam phase distortions in view of symmetric character of the aberrations of slab refractive index. To suppress parasitic oscillations inside the slab, dielectric coatings of wide sides of the slab are used. Main Results. We have demonstrated theoretically and experimentally that the usage of hyperthermal conductive plates together with the algorithm of pulse-width modulation provides stabilizing of the diode substrate temperature accurate within ± 0.1 °С and smoothing the temperature distribution along the plate surface accurate
6. Recent progress in diode-pumped mid-infrared vibronic solid-state lasers
International Nuclear Information System (INIS)
Sorokina, I.T.; Sorokin, E.; Mirov, S.; Schaffers, K.
2002-01-01
Full text: The last few years were marked by the increased interest of researchers towards the new class of transition-metal doped zinc chalcogenides. In particular Cr:ZnSe attracts a lot of attention as broadly tunable continuous-wave (cw), mode-locked and diode-pumped lasers operating around 2.5 mm. This interest is explained by the absence of other comparable tunable room-temperature laser sources in this spectral region. However, another member of the II-VI compounds family Cr:ZnS, has yet remained barely studied as a laser medium. Recently we demonstrated the first continuous-wave room-temperature tunable over more than 280 nm around 2.3 μm Cr 2+ :ZnS laser, pumped with a Co:MgF2 laser and yielding over 100 mW of output power. The most recent result is the development of a compact tunable over 700 nm continuous-wave room-temperature Cr 2+ :ZnS laser, pumped by the diode-pumped Er-fiber laser at 1.6 μm and generating 0.7 W of the linearly polarized radiation. We also demonstrated direct diode-pumping at 1.6 μm of the Cr 2+ :ZnS. Although the Cr:ZnS exhibited lower (relatively to the Cr:ZnSe) efficiency and output power due to the higher passive losses of the available Cr:ZnS samples, the analysis of the spectroscopic and laser data indicates the high potential of Cr:ZnS for compact broadly tunable mid-infrared systems, as well as for high power applications. The physics of the novel diode-pumped laser systems is highly interesting. It comprises the features of the ion-doped dielectric crystalline lasers and semiconductors. For example, we observe in these media, for the first time to our knowledge, a new nonlinear phenomenon, which is analogous to the opto-optical switching process, where the laser output of the diode-pumped continuous-wave Cr:ZnSe and Cr:ZnS lasers around 2.5 μm is modulated by only a few milliwatt of the visible (470-500 nm) and near-infrared radiation (740-770 nm). We present a physical explanation of the observed effect. Refs. 4 (author)
7. Tm:GGAG crystal for 2μm tunable diode-pumped laser
Science.gov (United States)
Šulc, Jan; Boháček, Pavel; Němec, Michal; Fibrich, Martin; Jelínková, Helena; Trunda, Bohumil; Havlák, Lubomír.; Jurek, Karel; Nikl, Martin
2016-04-01
The spectroscopy properties and wavelength tunability of diode pumped laser based on Tm-doped mixed gadolinium-gallium-aluminium garnet Gd3(GaxAl1-x)5O12 (Tm:GGAG) single crystal were investigated for the first time. The crystal was grown by Czochralski method in a slightly oxidative atmosphere using an iridium crucible. The tested Tm:GGAG sample was cut from the grown crystal boule perpendicularly to growth direction (c-axis). The composition of sample was determined using electron microprobe X-ray elemental analysis. For spectroscopy and laser experiments 3.5mm thick plane-parallel face-polished plate (without AR coatings) with composition Gd2.76Tm0.0736Ga2.67Al2.50O12 (2.67 at.% Tm/Gd) was used. A fiber (core diameter 400 μm, NA= 0.22) coupled laser diode (emission wavelength 786 nm) was used for longitudinal Tm:GGAG pumping. The laser diode was operating in the pulsed regime (10 ms pulse length, 10 Hz repetition rate, maximum power amplitude 18 W). The 145mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (HR @ 1.8- 2.10 μm, HT @ 0.78 μm) and curved (r = 150mm) output coupler with a reflectivity of » 97% @ 1.8- 2.10 µm. The maximum laser output power amplitude 1.14W was obtained at wavelength 2003nm for absorbed pump power amplitude 4.12W. The laser slope efficiency was 37% in respect to absorbed pumping power. Wavelength tuning was accomplished by using 2mm thick MgF2 birefringent filter placed inside the laser resonator at the Brewster angle. The laser was continuously tunable over 180nm in a spectral region from 1856nm to 2036 nm.
8. Optimum design of a multi-stage dye-laser amplifier pumped with Cu-vapor lasers
International Nuclear Information System (INIS)
Maeda, Mitsuo; Uchiumi, Michihiro
1990-01-01
A numerical simulation code, based on the one-dimensional photon transport equation, was developed and analyzed to evaluate the performances of Rhodamine 6G dye laser amplifiers pumped with Cu-vapor lasers. The upper singlet-state absorption played an important role to determine the efficiency. The simulation code was applied to optimize a multi-stage amplifier system with a pulsed or a CW dye-laser oscillator. The analytical results gave a useful guideline to design a high-power pulsed dye-laser system for atomic uranium enrichment. (author)
9. A High-Energy Good-Beam-Quality Krypton-Lamp-Pumped Nd:YAG Solid-State Laser with One Pump Cavity
Institute of Scientific and Technical Information of China (English)
LIU Xue-Sheng; WANG Zhi-Yong; YAN Xin; CAO Ying-Hua
2008-01-01
We investigate a high-energy good-beam-quality krypton-lamp-pumped pulsed Nd:YAG solid-state laser with one pump cavity.The symmetrical resonator laser is developed and is rated at 80 J with beam parameter product 12mm mrad.The total system electro-optics efficiency of the lamp-pumped YAG laser is as high as 3.3% and the stability of output energy is ±2% with pulse width tunable between 0.1 ms and 10ms.The experimental results are consistent with the theoretical analysis and simulation.
10. Single-mode, All-Solid-State Nd:YAG Laser Pumped UV Converter
Science.gov (United States)
Prasad, Narasimha S.; Armstrong, Darrell, J.; Edwards, William C.; Singh, Upendra N.
2008-01-01
In this paper, the status of a high-energy, all solid-state Nd:YAG laser pumped nonlinear optics based UV converter development is discussed. The high-energy UV transmitter technology is being developed for ozone sensing applications from space based platforms using differential lidar technique. The goal is to generate greater than 200 mJ/pulse with 10-50 Hz PRF at wavelengths of 308 nm and 320 nm. A diode-pumped, all-solid-state and single longitudinal mode Nd:YAG laser designed to provide conductively cooled operation at 1064 nm has been built and tested. Currently, this pump laser provides an output pulse energy of >1 J/pulse at 50 Hz PRF and a pulsewidth of 22 ns with an electrical-to-optical system efficiency of greater than 7% and a M(sup 2) value of UV converter arrangement basically consists of an IR Optical Parametric Oscillator (OPO) and a Sum Frequency Generator (SFG) setups that are pumped by 532 nm wavelength obtained via Second Harmonic Generation (SHG). In this paper, the operation of an inter cavity SFG with CW laser seeding scheme generating 320 nm wavelength is presented. Efforts are underway to improve conversion efficiency of this mJ class UV converter by modifying the spatial beam profile of the pump laser.
11. Ultraviolet SO lasers optically pumped by a tunable, line-narrowed KrF laser
International Nuclear Information System (INIS)
Stuart, B.C.D.
1992-06-01
The feasibility of an ultraviolet energy storage laser based on the long-lived sulfur monoxide A 3 π-χ 3 Σ - electronic transition was investigated, and an ultraviolet laser based on the short-lived SO(B 3 Σ - -χ 3 Σ - ) transition was demonstrated and modeled. Both were optically pumped by a continuously tunable, line-narrowed KrF laser developed for efficient rotationally resolved excitation of SO. SO was produced by both microwave discharge and excimer laser photolysis of the precursor molecules SO 2 and SOCl 2 , with a maximum SO concentration (10 16 cm -3 ) generated by ArF (193 nm) photodissociation of SO 2 . Laser induced fluorescence of SO was used to study the excitation spectroscopy, vibrational branching ratios, lifetimes and deactivation rates. The radiative lifetime of SO(A 3 π 2 ,v' = 5) was measured to be 6.9 μs and that of SO(B,v' = 1) to be 33 ns. Lifetimes in the highly perturbed SO(B,v' = 2) level ranged from 28--90 ns. Measurements and modeling of the excitation saturation fluence as a function of buffer gas pressure determined what fraction of the ground state SO(X) molecules could be excited to SO(A) or SO(B). No evidence of excited state absorption was seen. Lasing on six new ultraviolet SO(B-X) vibrational bands in the range 262--315 nm was demonstrated. SO(B-X) pulse energies of up to 11 μJ were obtained and the gain coefficient was estimated to be 0.1 cm -1 . A multi-level rate equation model of the SO(B-X) excitation and lasing transitions, including collisional rotational mixing, described the dynamics of the lasing and measured output very well. Modeling showed and experiments confirmed that the maximum possible SO laser gain simply corresponded to saturating the excitation of a single rotational level. Collisional coupling of the rotational levels increased the laser output energy
12. LD-cladding-pumped 50 pm linewidth Tm 3+ -doped silica fiber laser.
Science.gov (United States)
Yunjun, Zhang; Baoquan, Yao; Youlun, Ju; Hui, Zhou; Yuezhu, Wang
2008-05-26
We report on a Tm(3+)-doped fiber laser source operating at 1936.4 nm with a very narrow linewidth (50 pm) laser output. Up to 2.4 W cw laser power was obtained from an 82 cm long Tm(3+)-doped multimode-core fiber cladding pumped by a 792 nm laser diode (LD). The fiber laser cavity included a high-reflective dichroic and a low-reflective FBG output coupler. The multimode fiber Bragg grating (FBG) transmission spectrum and output laser spectrum were measured. By adjusting the distance between the dichroic and the Tm(3+)-doped fiber end, the multipeak laser spectrum changed to a single-peak laser spectrum.
13. Angular dependence of the sup(6)Li(πsup(+),sup(3)He)sup(3)He reaction
International Nuclear Information System (INIS)
McParland, B.J.; Auld, E.G.; Couvert, P.
1985-02-01
Angular distributions of the differential cross sections for the pionic fission sup(6)Li(πsup(+),sup(3)He)sup(3)He have been measured at pion energies of 60 and 80 MeV. The differential cross section is found to decrease monotonically with cossup(2)thetasup(*) and is compared with a theoretical prediction
14. High-efficiency, 154 W CW, diode-pumped Raman fiber laser with brightness enhancement.
Science.gov (United States)
Glick, Yaakov; Fromzel, Viktor; Zhang, Jun; Ter-Gabrielyan, Nikolay; Dubinskii, Mark
2017-01-20
We demonstrate a high-power, high-efficiency Raman fiber laser pumped directly by laser diode modules at 978 nm. 154 W of CW power were obtained at a wavelength of 1023 nm with an optical to optical efficiency of 65%. A commercial graded-index (GRIN) core fiber acts as the Raman fiber in a power oscillator configuration, which includes spectral selection to prevent generation of the second Stokes. In addition, brightness enhancement of the pump beam by a factor of 8.4 is attained due to the Raman gain distribution profile in the GRIN fiber. To the best of our knowledge this is the highest power and highest efficiency Raman fiber laser demonstrated in any configuration allowing brightness enhancement (i.e., in either cladding-pumped configuration or with GRIN fibers, excluding step-index core pumped), regardless of pumping scheme (i.e., either diode pumped or fiber laser pumped).
15. A high-power diode-laser-pumped CW Nd:YAG laser using a stable-unstable resonator
International Nuclear Information System (INIS)
Mudge, M.; Ostermeyer, P.; Veitch, J.; Munch, J.; Hamilton, M.W.
2000-01-01
Full text: The design and operation of a power-scalable diode-laser-pumped CW Nd:YAG zigzag slab laser that uses a stable-unstable resonator with a graded reflectivity mirror as an output coupler is described. We demonstrate control of the thermal lens strength in the unstable plane and weak thermal lensing in the stable plane that is independent of pump power, vital for efficient scalability. This enabled CW operation of the stable-unstable resonator with excellent near- and far-field beam quality
16. Interspecies Ion Diffusion Studies using DT, DT(3He), and DT(H) Implosions
Science.gov (United States)
Kim, Y.; Herrmann, H. W.; Schmitt, M. J.; Kagan, G.; McEvoy, A. M.; Hoffman, N. M.; Gales, S.; Leatherland, A.; Gatu Johnson, M.; Frenje, J.; Glevov, V. Yu; Forrest, C.
2015-11-01
Anomalous ICF yield degradation has been observed from gas fills containing mixtures (i.e., D(3He), DT(3He), D(Ar), and even DT). Interspecies ion diffusion theory has been suggested as a possible cause resulting from gradient-driven diffusion (i.e., pressure, electric potential, and temperature) which forces lower mass ions away from core and higher mass ions toward core. The theory predicts hydrogen addition to deuterium or tritium should result in increased yield compared to expected yield, which is opposite to 3He addition. At Omega laser facility, we have tested hydro-equivalent fills of DT, DT(3He), and DT(H) with the assumption that same fuel mass and particle pressure will provide identical convergence. Preliminary results verify a factor of 2 yield reduction relative to scaling when 3He added to DT. At DT(H) case, however, no significant yield degradation or a slight yield enhancement was observed which agrees with the interspecies ion diffusion theory. Detailed experiment results and simulation are needed to confirm the initial observation.
17. Solar-Pumped TEM₀₀ Mode Nd:YAG laser.
Science.gov (United States)
Liang, Dawei; Almeida, Joana
2013-10-21
Here we show a significant advance in solar-pumped laser beam brightness by utilizing a 1.0 m diameter Fresnel lens and a 3 mm diameter Nd:YAG single-crystal rod. The incoming solar radiation is firstly focused by the Fresnel lens on a solar tracker. A large aspheric lens and a 2D-CPC concentrator are then combined to further compress the concentrated solar radiation along the thin laser rod within a V-shaped pumping cavity. 2.3 W cw TEM₀₀ (M² ≤ 1.1) solar laser power is finally produced, attaining 1.9 W laser beam brightness figure of merit, which is 6.6 times higher than the previous record. For multimode operation, 8.1 W cw laser power is produced, corresponding to 143% enhancement in collection efficiency.
18. On the 3He anomaly in hot subdwarf B stars
Science.gov (United States)
Schneider, David; Irrgang, Andreas; Heber, Ulrich; Nieva, Maria F.; Przybilla, Norbert
2017-12-01
Decades ago, 3He isotope enrichment in helium-weak B-type main-sequence, in blue horizontal branch and in hot subdwarf B (sdB) stars, i.e., helium-core burning stars of the extreme horizontal branch, were discovered. Diffusion processes in the atmosphere of these stars lead to the observed abundance anomalies. Quantitative spectral analyses of high-resolution spectra to derive photospheric isotopic helium abundance ratios for known 3He sdBs have not been performed yet. We present preliminary results of high-resolution and high S/N spectra to determine the 3He and 4He abundances of nine known 3He sdBs. We used a hybrid local/non-local thermodynamic equilibrium (LTE/NLTE) approach for B-type stars investigating multiple He i lines, including λ4922 Å and λ6678 Å, which show the strongest isotopic shifts in the optical spectral range.We also report the discovery of four new 3He sdBs from the ESO Supernova Progenitor survey. Most of the 3He sdBs cluster in a narrow temperature strip between ˜ 26000 K and ˜ 30000 K and have almost no atmospheric 4He at all. Interestingly, three 3He sdBs show evidence for vertical helium stratification.
19. On the 3He anomaly in hot subdwarf B stars
Directory of Open Access Journals (Sweden)
Schneider David
2017-12-01
Full Text Available Decades ago, 3He isotope enrichment in helium-weak B-type main-sequence, in blue horizontal branch and in hot subdwarf B (sdB stars, i.e., helium-core burning stars of the extreme horizontal branch, were discovered. Diffusion processes in the atmosphere of these stars lead to the observed abundance anomalies. Quantitative spectral analyses of high-resolution spectra to derive photospheric isotopic helium abundance ratios for known 3He sdBs have not been performed yet. We present preliminary results of high-resolution and high S/N spectra to determine the 3He and 4He abundances of nine known 3He sdBs. We used a hybrid local/non-local thermodynamic equilibrium (LTE/NLTE approach for B-type stars investigating multiple He i lines, including λ4922 Å and λ6678 Å, which show the strongest isotopic shifts in the optical spectral range.We also report the discovery of four new 3He sdBs from the ESO Supernova Progenitor survey. Most of the 3He sdBs cluster in a narrow temperature strip between ∼ 26000 K and ∼ 30000 K and have almost no atmospheric 4He at all. Interestingly, three 3He sdBs show evidence for vertical helium stratification.
20. Improving solar-pumped laser efficiency by a ring-array concentrator
Science.gov (United States)
Tibúrcio, Bruno D.; Liang, Dawei; Almeida, Joana; Matos, Rodrigo; Vistas, Cláudia R.
2018-01-01
We report here a compact pumping scheme for achieving large improvement in collection and conversion efficiency of a Nd:YAG solar-pumped laser by an innovative ring-array solar concentrator. An aspheric fused silica lens was used to further concentrate the solar radiation from the focal region of the 1.5-m-diameter ring-array concentrator to a 5.0-mm-diameter, 20-mm-length Nd:YAG single-crystal rod within a conical-shaped pump cavity, enabling multipass pumping to the laser rod. 67.3-W continuous-wave solar laser power was numerically calculated, corresponding to 38.2-W / m2 solar laser collection efficiency, being 1.22 and 1.27 times more than the state-of-the-art records by both heliostat-parabolic mirror and Fresnel lens solar laser systems, respectively. 4.0% conversion efficiency and 0.021-W brightness figure of merit were also numerically obtained, corresponding to 1.25 and 1.62 times enhancement over the previous records, respectively. The influence of tracking error on solar laser output power was also analyzed.
1. Ultralow-threshold electrically pumped quantum-dot photonic-crystal nanocavity laser
Science.gov (United States)
Ellis, Bryan; Mayer, Marie A.; Shambat, Gary; Sarmiento, Tomas; Harris, James; Haller, Eugene E.; Vučković, Jelena
2011-05-01
Efficient, low-threshold and compact semiconductor laser sources are under investigation for many applications in high-speed communications, information processing and optical interconnects. The best edge-emitting and vertical-cavity surface-emitting lasers have thresholds on the order of 100 µA (refs 1,2), but dissipate too much power to be practical for many applications, particularly optical interconnects. Optically pumped photonic-crystal nanocavity lasers represent the state of the art in low-threshold lasers; however, to be practical, techniques to electrically pump these structures must be developed. Here, we demonstrate a quantum-dot photonic-crystal nanocavity laser in gallium arsenide pumped by a lateral p-i-n junction formed by ion implantation. Continuous-wave lasing is observed at temperatures up to 150 K. Thresholds of only 181 nA at 50 K and 287 nA at 150 K are observed--the lowest thresholds ever observed in any type of electrically pumped laser.
2. Stochastic resonance for signal-modulated pump noise in a single-mode laser
Institute of Scientific and Technical Information of China (English)
Liangying Zhang; Li Cao; Fahui Zhu
2006-01-01
By adopting the gain-noise model of the single-mode laser in which with bias and periodical signals serve as inputs, combining with the effect of coloured pump noise, we use the linear approximation method to calculate the power spectrum and signal-to-noise ratio (SNR) of the laser intensity under the condition of pump noise and quantum noise cross-related in the form of δ function. It is found that with the change of pump noise correlation time, both SNR and the output power will occur stochastic resonance (SR). If the bias signal α is very small, changing the intensities of pump noise and quantum noise respectively does not lead to the appearance of SR in the SNR; while α increases to a certain number, SR appears.
3. Theoretical investigation of output features of a diode-pumped rubidium vapor laser
Science.gov (United States)
Wang, You; Cai, He; Zhang, Wei; Xue, Liangping; Wang, Hongyuan; Han, Juhong
2014-02-01
In the recent years, diode-pumped alkali lasers (DPALs) have been paid many attentions because of their excellent performances. In fact, the characteristics of a DPAL strongly depend on the physical features of buffer gases. In this report, we selected a diode-pumped rubidium vapor laser (DPRVL), which is an important type among three common DPALs, to investigate how the characteristics of a DPRVL are affected by different conditions. The results signify that the population ratio of two excitation energy-levels are close to that corresponding to thermal equilibrium as the pressure of buffer gases and the temperature of a vapor cell become higher. It has been found that quenching of the upper levels cannot be simply ignored especially for the case of weak pump. The conclusions are thought to be helpful for the configuration design of an end-pumped DPAL.
4. Short-wavelength soft-x-ray laser pumped in double-pulse single-beam non-normal incidence
International Nuclear Information System (INIS)
Zimmer, D.; Ros, D.; Guilbaud, O.; Habib, J.; Kazamias, S.; Zielbauer, B.; Bagnoud, V.; Ecker, B.; Aurand, B.; Kuehl, T.; Hochhaus, D. C.; Neumayer, P.
2010-01-01
We demonstrated a 7.36 nm Ni-like samarium soft-x-ray laser, pumped by 36 J of a neodymium:glass chirped-pulse amplification laser. Double-pulse single-beam non-normal-incidence pumping was applied for efficient soft-x-ray laser generation. In this case, the applied technique included a single-optic focusing geometry for large beam diameters, a single-pass grating compressor, traveling-wave tuning capability, and an optimized high-energy laser double pulse. This scheme has the potential for even shorter-wavelength soft-x-ray laser pumping.
5. D-3He fuel cycles for neutron lean reactors
International Nuclear Information System (INIS)
Kernbichler, W.; Miley, G.H.; Heindler, M.
1989-01-01
The intrinsic potential of D-3He as a reactor fuel is investigated for a large range of 3He to D density ratios. A steady-state zero-dimensional reactor model is developed in which much care is attributed to a proper treatment of fast fusion products. Useful ranges of reactor parameters as well as temperature-density windows for driven and ignited operation are identified. Various figures of merit are calculated, such as power densities, net power production, neutron production, tritium load and radiative power. These results suggest several optimistic conclusions about the performance of D-3He as a reactor fuel
6. A 526 W Diode-Pumped Nd:YAG Ceramic Slab Laser
International Nuclear Information System (INIS)
Chen Yan-Zhong; Bo Yong; Xu Jian; Xu Yi-Ting; Xu Jia-Lin; Guo Ya-Ding; Yang Feng-Tu; Peng Qin-Jun; Cui Da-Fu; Xu Zu-Yan; Liu Wen-Bin; Jiang Ben-Xue; Kou Hua-Min; Pan Yu-Bai; Jiang Dong-Liang
2011-01-01
A diode-side-pumped Nd:YAG ceramic slab laser with a high power output is presented. An average power of 526 W is achieved at 1064 nm with a repetition rate of 120 Hz and a pulse width of 180 μs from a 93mm × 52mm × 8 mm ceramic slab at a pump power of 1928 W, corresponding to an optical-to-optical efficiency of 27.3%. (fundamental areas of phenomenology(including applications))
7. Towards diode-pumped mid-infrared praseodymium-ytterbium-doped fluoride fiber lasers
Science.gov (United States)
Woodward, R. I.; Hudson, D. D.; Jackson, S. D.
2018-02-01
We explore the potential of a new mid-infrared laser transition in praseodymium-doped fluoride fiber for emission around 3.4 μm, which can be conveniently pumped by 0.975 μm diodes via ytterbium sensitizer co-doping. Optimal cavity designs are determined through spectroscopic measurements and numerical modeling, suggesting that practical diode-pumped watt-level mid-infrared fiber sources beyond 3 μm could be achieved.
8. Interpreting coherent anti-Stokes Raman spectra measured with multimode Nd:YAG pump lasers
International Nuclear Information System (INIS)
Farrow, R.L.; Rahn, L.A.
1985-01-01
We report comparisons of coherent anti-Stokes Raman spectroscopy (CARS) measurements using single-axial-and multiaxial-mode Nd:YAG lasers. Our results demonstrate the validity of a recently proposed convolution expression for unresolved CARS spectra. The results also support the use of a relative delay of several coherence lengths between pump-beam paths for reducing the effects of pump-field statistics on the CARS spectral profile
9. Intensity and absorbed-power distribution in a cylindrical solar-pumped dye laser
Science.gov (United States)
Williams, M. D.
1984-01-01
The internal intensity and absorbed-power distribution of a simplified hypothetical dye laser of cylindrical geometry is calculated. Total absorbed power is also calculated and compared with laboratory measurements of lasing-threshold energy deposition in a dye cell to determine the suitability of solar radiation as a pump source or, alternatively, what modifications, if any, are necessary to the hypothetical system for solar pumping.
10. Kinetic analysis of rare gas metastable production and optically pumped Xe lasers
Science.gov (United States)
Demyanov, A. V.; Kochetov, I. V.; Mikheyev, P. A.; Azyazov, V. N.; Heaven, M. C.
2018-01-01
Optically pumped all-rare-gas lasers use metastable rare gas atoms as the lasing species in mixtures with He or Ar buffer gas. The metastables are generated in a glow discharge, and we report model calculations for the optimal production of Ne*, Ar*, Kr* and Xe*. Discharge efficiency was estimated by solving the Boltzmann equation. Laser efficiency, gain and output power of the CW optically pumped Xe laser were assessed as functions of heavier rare gas content, pressure, optical pump intensity and the optical path length. It was found that, for efficient operation the heavier rare gas content has to be of the order of one percent or less, and the total pressure—in the range 0.3-1.5 atm. Output power and specific discharge power increase approximately linearly with pump intensity over the output range from 300-500 W cm-2. Ternary mixtures Xe:Ar:He were found to be the most promising. Total laser efficiency was found to be nearly the same for pumping the 2p8 or 2p9 state, reaching 61%-70% for a pump intensity of ~720 W cm-2 when the Xe fraction was in the range 0.001 ÷ 0.01 and Ar fraction—0.1 ÷ 0.5. However, when the 2p8 state was pumped, the maximum total efficiency occurred at larger pressures than for pumping of the 2p9 state. The discharge power density required to sustain a sufficient Xe* number density was in the range of tens of watts per cubic centimeter for 50% Ar in the mixture.
11. Diode-pumped glass laser (10 J X 10 HZ) development
International Nuclear Information System (INIS)
Tadashi Kanabe; Toshiyuki Kawashima; Masanobu Yamanaka; Masahiro Nakatsuka; Yasukazu Izawa; Takeshi Kanzaki; Hirofumi Kan; Sadao Nakai
2002-01-01
A high-energy, high beam quality, diode-pumped 1053-nm Nd:phosphate glass laser amplifier has been demonstrated in order to verify the conceptual design of HALNA (High Average-power Laser for Nuclear-fusion Application): a diode-pumped solid-state laser based on a water-cooled zig-zag slab optical geometry. This amplifier yielded 8.5 J output energy per pulse at 0.5 Hz in a 20 ns pulse of two times the diffraction limit beam quality with an optical-to-optical conversion efficiency of 10.9%. The experimental results revealed that the primary requirements for the IFE driver, such as diode-pumping, energy storage and extraction efficiencies, and beam quality have been fulfilled
12. Scalable pumping approach for extracting the maximum TEM(00) solar laser power.
Science.gov (United States)
Liang, Dawei; Almeida, Joana; Vistas, Cláudia R
2014-10-20
A scalable TEM(00) solar laser pumping approach is composed of four pairs of first-stage Fresnel lens-folding mirror collectors, four fused-silica secondary concentrators with light guides of rectangular cross-section for radiation homogenization, four hollow two-dimensional compound parabolic concentrators for further concentration of uniform radiations from the light guides to a 3 mm diameter, 76 mm length Nd:YAG rod within four V-shaped pumping cavities. An asymmetric resonator ensures an efficient large-mode matching between pump light and oscillating laser light. Laser power of 59.1 W TEM(00) is calculated by ZEMAX and LASCAD numerical analysis, revealing 20 times improvement in brightness figure of merit.
13. Pump-probe experiments in atoms involving laser and synchrotron radiation: an overview
International Nuclear Information System (INIS)
Wuilleumier, F J; Meyer, M
2006-01-01
The combined use of laser and synchrotron radiations for atomic photoionization studies started in the early 1980s. The strong potential of these pump-probe experiments to gain information on excited atomic states is illustrated through some exemplary studies. The first series of experiments carried out with the early synchrotron sources, from 1960 to about 1995, are reviewed, including photoionization of unpolarized and polarized excited atoms, and time-resolved laser-synchrotron studies. With the most advanced generation of synchrotron sources, a whole new class of pump-probe experiments benefiting from the high brightness of the new synchrotron beams has been developed since 1996. A detailed review of these studies as well as possible future applications of pump-probe experiments using third generation synchrotron sources and free electron lasers is presented. (topical review)
14. Sub-100 fs high average power directly blue-diode-laser-pumped Ti:sapphire oscillator
Science.gov (United States)
Rohrbacher, Andreas; Markovic, Vesna; Pallmann, Wolfgang; Resan, Bojan
2016-03-01
Ti:sapphire oscillators are a proven technology to generate sub-100 fs (even sub-10 fs) pulses in the near infrared and are widely used in many high impact scientific fields. However, the need for a bulky, expensive and complex pump source, typically a frequency-doubled multi-watt neodymium or optically pumped semiconductor laser, represents the main obstacle to more widespread use. The recent development of blue diodes emitting over 1 W has opened up the possibility of directly diode-laser-pumped Ti:sapphire oscillators. Beside the lower cost and footprint, a direct diode pumping provides better reliability, higher efficiency and better pointing stability to name a few. The challenges that it poses are lower absorption of Ti:sapphire at available diode wavelengths and lower brightness compared to typical green pump lasers. For practical applications such as bio-medicine and nano-structuring, output powers in excess of 100 mW and sub-100 fs pulses are required. In this paper, we demonstrate a high average power directly blue-diode-laser-pumped Ti:sapphire oscillator without active cooling. The SESAM modelocking ensures reliable self-starting and robust operation. We will present two configurations emitting 460 mW in 82 fs pulses and 350 mW in 65 fs pulses, both operating at 92 MHz. The maximum obtained pulse energy reaches 5 nJ. A double-sided pumping scheme with two high power blue diode lasers was used for the output power scaling. The cavity design and the experimental results will be discussed in more details.
15. Intensity noise properties of Nd:YVO 4 microchip lasers pumped with an amplitude squeezed diode laser
Science.gov (United States)
Becher, C.; Boller, K.-J.
1998-02-01
We report on intensity noise measurements of single-frequency Nd:YVO 4 microchip lasers optically pumped with amplitude squeezed light from an injection-locked diode laser. Calibrated homodyne measurements show a minimum intensity noise of 10.1 dB above the SQL at a frequency of 100 kHz. The measured intensity noise spectra are described with high accuracy by a theoretical model based on the quantum mechanical Langevin rate equations, including classical and quantum noise sources.
16. Bistable direction switching in an off-axis pumped continuous wave ruby laser
Science.gov (United States)
Afzal, R. Sohrab; Lawandy, N. M.
1988-01-01
A report is presented of the observation of hysteretic bistable direction switching in a single-mode CW ruby laser system. This effect is only observed when the pump beam which is focused into the ruby rod is misaligned with respect to the rod end faces. At low pump powers, the ruby lases in a mode nearly collinear with the pump axis. At a higher pump power the ruby switches to a mode that is collinear with the rod end faces and preserves the original polarization. The effect is large enough to switch the beam by an angle equal to twice the diffraction angle. The observations show that under steady-state pumping, a CW ruby laser can exhibit bistable operation in its output direction and power. A calculation using the heat equation with two concentric cylinders with one as a heat source (pump laser) and the outer wall of the other held at 77 K, gives an increase in core temperature of about 0.01 K. Therefore, the increase in temperature is not large enough to change the index of refraction to account for such large macroscopic effects.
17. The elimination of pump depletion in laser-plasma beat-wave accelerators
International Nuclear Information System (INIS)
Ma Jinxiu; Xu Zhizhan
1988-01-01
The pump depletion is a severe problem which hinders the laser-plasma beat-wave accelerator concept from being practical. Starting with the weak relativistic equation of beat-wave excitation of electron plasma waves, the authors have derived the condition for eliminating the pump depletion in the fame moving with the light pulse for arbitrary pulse shapes. It is shown that the depletion can be eliminated by a phase jump of π at the center of the pump pulse and by the appropriated choice of initial plasma density detuning. The numerical calculation have yielded the dependence of the initial detuning on the pump intensity for square pump pulses, and have supported the methods used in this paper
18. High pumping-power fiber combiner for double-cladding fiber lasers and amplifiers
Science.gov (United States)
Zheng, Jinkun; Zhao, Wei; Zhao, Baoyin; Li, Zhe; Chang, Chang; Li, Gang; Gao, Qi; Ju, Pei; Gao, Wei; She, Shengfei; Wu, Peng; Hou, Chaoqi; Li, Weinan
2018-03-01
A high pumping-power fiber combiner for backward pumping configurations is fabricated and demonstrated by manufacturing process refinement. The pump power handling capability of every pump fiber can extend to 600 W, corresponding to the average pump coupling efficiency of 94.83%. Totally, 2.67-kW output power with the beam quality factor M2 of 1.41 was obtained, using this combiner in the fiber amplifier experimental setup. In addition, the temperature of the splicing region was less than 50.0°C in the designed combiner under the action of circulating cooling water. The experimental results prove that the designed combiner is a promising integrated all-fiber device for multikilowatt continuous-wave fiber laser with excellent beam quality.
19. (3He,xn), (3He,pxn) and (3He, fission) reactions on 206Pb between 80 and 200MeV
International Nuclear Information System (INIS)
Andre, C.; Gauvin, H.; Le Beyec, Y.; Porile, N.T.
1976-01-01
The reactions induced in 206 Pb by 3 He particles having energies between 80 and 200MeV have been studied. Excitation functions for ( 3 He,xn) with x=3 to 14 and for ( 3 He,pxn) with x=2 to 5 have been obtained. Angular distributions of fission fragments were measured at 100, 125, 150 and 175MeV and total fission cross-sections were deduced from the data. On the basis of these results, analysis is attempted to examine the characteristics of reaction mechanisms. From these results it is concluded that non-compound processes play an important role in the reactions. Two features are characteristic of these processes: large cross-sections for charged particle emission and angular distribution of fission fragments closed to isotropy in the laboratory system. In the energy range 25 to 45MeV/nucleon, a comparison was made between the present results and those from an experimental study of α-particle induced reactions on 206 Pb. Also a comparison was made with an α-nucleus collision model applied to 206 Pb. All the observations strongly suggest a breakup of the projectile 3 He followed by the interactions of the fragments with the target nucleus [fr
20. Polarised two-photon excitation of quantum well excitons for manipulation of optically pumped terahertz lasers
Energy Technology Data Exchange (ETDEWEB)
Slavcheva, G., E-mail: [email protected] [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); Kavokin, A.V., E-mail: [email protected] [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Spin Optics Laboratory, St. Petersburg State University, 1, Ulyanovskaya 198504 (Russian Federation)
2014-11-15
Optical pumping of excited exciton states in a semiconductor quantum well embedded in a microcavity is a tool for realisation of ultra-compact terahertz (THz) lasers based on stimulated optical transition between excited (2p) and ground (1s) exciton state. We show that the probability of two-photon absorption by a 2p-exciton is strongly dependent on the polarisation of both pumping photons. Five-fold variation of the threshold power for terahertz lasing by switching from circular to co-linear pumping is predicted. We identify photon polarisation configurations for achieving maximum THz photon generation quantum efficiency.
1. Laser printed graphene on polyimide electrodes for magnetohydrodynamic pumping of saline fluids
KAUST Repository
Khan, Mohammed Asadullah; Hristovski, Ilija R.; Marinaro, Giovanni; Mohammed, Hanan; Kosel, Jü rgen
2017-01-01
An efficient, scalable pumping device is reported that avoids moving parts and is fabricated with a cost-effective method. The magnetohydrodynamic pump has electrodes facilely made by laser printing of polyimide. The electrodes exhibit a low sheet resistance of 22.75 Ω/square. The pump is implemented in a channel of 240 mm2 cross-section and has an electrode length of 5 mm. When powered by 7.3 V and 12.43 mA/cm2, it produces 13.02 mm/s flow velocity.
2. Laser printed graphene on polyimide electrodes for magnetohydrodynamic pumping of saline fluids
KAUST Repository
2017-08-09
An efficient, scalable pumping device is reported that avoids moving parts and is fabricated with a cost-effective method. The magnetohydrodynamic pump has electrodes facilely made by laser printing of polyimide. The electrodes exhibit a low sheet resistance of 22.75 Ω/square. The pump is implemented in a channel of 240 mm2 cross-section and has an electrode length of 5 mm. When powered by 7.3 V and 12.43 mA/cm2, it produces 13.02 mm/s flow velocity.
3. 3He and chlorofluorocarbons (CFC) in the Southern Ocean
International Nuclear Information System (INIS)
Jean-Baptiste, P.; Jamous, D.; Mantisi, F.; Memery, L.; Universite Paris 6
1991-01-01
The distribution of 3 He across the Southern Ocean is depicted on the basis of a meridional section between Antarctica and South Africa measured during the INDIGO-3 survey (1988). A core of δ 3 He values above 10% is observed south of the Polar Front, associated with very low CFC concentrations. This 3 He enriched layer is documented from the GEOSECS and INDIGO 3 He data in the Southern Ocean. It is found at a density level around θ σ =27.8 in all the waters close to Antarctica (i.e. south of 50 degS). Its zonal distribution suggests that it is likely that it originates from the central/eastern Pacific. Hence, it provides an indication of the deep Pacific waters in the Antarctic Circumpolar Current, which are not easily detectable from the standard hydrographic parameters. (author). 19 refs.; 8 figs
4. Thermodynamic properties of 3He--4He mixtures near Tlambda
International Nuclear Information System (INIS)
Kakizaki, A.; Satoh, T.
1976-01-01
In order to investigate 3 He impurity effects on the superfluid transition, measurements were made on the thermodynamic quantities, specific heat, thermal expansion coefficients, and pressure dependence of the lambda-transition temperature of three 3 He-- 4 He mixtures and pure 4 He in the neighborhood of the lambda-transition temperature under their saturated vapor pressure. Making use of these measured quantities, it is shown that the so-called Pippard--Buckingham--Fairbank relation holds for 3 He-- 4 He mixtures as well as for pure 4 He, at least in the temperature region of 10 -4 K less than or equal to absolute value (T - T/sub lambda/) less than or equal to 10 -2 K. Based on this, the 3 He impurity effects on the behavior of the specific heat near the lambda-transition are discussed
5. Recent {sup 3}He radio frequency heating experiments on JET
Energy Technology Data Exchange (ETDEWEB)
Van Eester, D. [Association Euratom-Belgian State, LPP-ERM/KMS, TEC, Brussels (Belgium); Imbeaux, F.; Joffrin, E. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France)] [and others
2003-07-01
Various ITER relevant experiments using {sup 3}He in a majority D plasma were performed in the recent JET campaigns. Two types can be distinguished: dedicated studies of the various RF heating scenarios which rely on the presence of {sup 3}He, and physics studies using RF heating as a working tool to provide a tunable heat source. As the success of a number of these experiments depended on the capability to keep the {sup 3}He concentration fixed, real time control of the {sup 3}He concentration was developed and used. This paper presents a brief overview of the results obtained, zooms in on some of the more interesting recent findings and discusses some of the theoretical background. (authors)
6. Spin polarized 3He: a ''new'' quantum fluid
International Nuclear Information System (INIS)
Lhuillier, C.; Laloe, F.
1979-01-01
The physical properties of a 3 He fluid are studied, in which all nuclear spins are parallel to each other (fully polarized 3 He). At low temperatures, significant differences can exist between this polarized fluid and normal 3 He. The origin of these differences is purely quantum mechanical and arises from the Pauli exclusion principle. At low densities, only the transport properties of the gas are modified. At higher densities. The equilibrium properties (virial coefficients) are also changed by the nuclear polarization. Changes of the liquid-vapour or liquid-solid equilibrium pressures, as well as modifications of the 3 He- 4 He mixture phase diagram are predicted. This article gives a preliminary theoretical study of these new effects. Experimental prospects are briefly discussed [fr
7. Demonstrations of diode-pumped and grating-tuned ZnSe:Cr2+ lasers
International Nuclear Information System (INIS)
Page, R.H.; Skidmore, J.A.; Schaffers, K.I.; Beach, R.J.; Payne, S.A.; Krupke, W.F.
1996-09-01
Within the last few years, divalent-transition-metal-doped II-VI material class has been proposed as source of new tunable mid-IR lasers. Cr 2+ is a prime laser candidate on account of its high luminescence quantum yield and the expectation that ESA would be absent. The first ZnSe:Cr 2+ laser demonstrations were conducted in an end-pumped geometry with a tightly focused (0.2 mm spot) MgF 2 -Co 2+ laser beam, for a peak pump intensity well over 100 kW/cm 2 , so laser threshold was easily reached. Grating tuning experiments were done by replacing the cavity high-reflector with a diffraction grating. The diode array was removed and pump beam from a MgF 2 :Co 2+ laser was focused onto the crystal using the same cylindrical lens. Output wavelengths were checked with a monochromator. The long-wavelength limit of operation was 2799 nm. Short-wavelength cutoff was 2134 nm; even though the emission cross section remains substantial, self-absorption inhibits laser operation
8. The laser control system for the TRIUMF optically pumped polarized H- ion source
International Nuclear Information System (INIS)
Kadantsev, S.G.; Levy, C.D.P.; Mouat, M.M.
1994-08-01
The optically pumped polarized H - ion source at TRIUMF produces up to 100 μΑ dc of 78% polarized beam within an emittance of 1.0 π mm mrad and is now being prepared for an upcoming experiment at TRIUMF that will measure parity violation in pp scattering at 230 MeV. The optical pumping is accomplished by argon laser pumped Ti-sapphire lasers. The laser control system provides monitoring and precision control of the lasers for fast spin reversal up to 200 s -1 . To solve the problems of laser power and frequency stabilization during fast spin flipping, techniques and algorithms have been developed that significantly reduce the variation of laser frequency and power between spin states. The upgraded Faraday rotation system allows synchronous measurement of Rb thickness and polarization while spin flipping. The X Window environment provides both local and remote control to laser operators via a local area network and X window terminals. In this new environment issues such as access authorization, response time, operator interface consistency and ease of use are of particular importance. (author)
Science.gov (United States)
Lin, Di; Daniel, J M O; Gecevičius, M; Beresna, M; Kazansky, P G; Clarkson, W A
2014-09-15
A simple technique for directly generating a radially polarized output beam from a cladding-pumped ytterbium-doped fiber laser is reported. Our approach is based on the use of a nanograting spatially variant waveplate as an intracavity polarization-controlling element. The laser yielded ~32 W of output power (limited by available pump power) with a radially polarized TM (01)-mode output beam at 1040 nm with a corresponding slope efficiency of 66% and a polarization purity of 95%. The beam-propagation factor (M(2)) was measured to be ~1.9-2.1.
10. Compact fibre-laser-pumped Ho:YLF oscillator–amplifier system
CSIR Research Space (South Africa)
Koen, W
2010-04-01
Full Text Available of the amplifier crystal L and the pump spot radius wp ( Ω = 2pi · (1 − cosβ), with β = tan−1(wpL )). Calculating the local population in (3) and iterating (6) and (11) along the length of the amplifier crystal, we obtain the extracted photon densities...-pumped tunable Tm: silica- fibre laser. Appl. Phys. B 79, 559 (2004) 6. E. Lippert, S. Nicolas, G. Arisholm, K. Stenersen, G. Rustad, Mid- infrared laser source with high power and beam quality. Appl. Opt. 45, 3839 (2006) 7. S.A. Payne, L.L. Chase, L...
11. Hyperpolarised 3He gas production for magnetic resonance imaging of the human air ways
International Nuclear Information System (INIS)
Fichele, Stanislao
2002-01-01
This thesis describes the experimental techniques, and methods employed in hyperpolarised 3 He gas production and magnetic resonance imaging of the human air-ways, using spin-echo sequences and MR tagging techniques. An in-house polariser utilising the metastability optical pumping technique was constructed. The main results of this work are concerned with engineering difficulties involved in compressing HP 3 He and a large proportion of this PhD thesis details the design, construction, and performance of an in-house built peristaltic compressor. In preliminary imaging experiments using RARE, high signal to noise projection images of the lungs were acquired using less than 0.5 cm 3 (STP) of purely polarised HP gas. Later, increased HP gas quantities (typically 10 cm 3 ) were obtained by employing the peristaltic compressor. Consequently we could acquire 10 mm thick slices spanning the entire lung following a single 3 He gas bolus administration. Finally, the first results using MR tagging techniques in conjunction with 3 He imaging to track gas flow during an inspiratory and expiratory manoeuvre are presented. (author)
12. In situ polarized 3He system for the Magnetism Reflectometer at the Spallation Neutron Source.
Science.gov (United States)
Tong, X; Jiang, C Y; Lauter, V; Ambaye, H; Brown, D; Crow, L; Gentile, T R; Goyette, R; Lee, W T; Parizzi, A; Robertson, J L
2012-07-01
We report on the in situ polarized (3)He neutron polarization analyzer developed for the time-of-flight Magnetism Reflectometer at the Spallation Neutron Source at Oak Ridge National Laboratory. Using the spin exchange optical pumping method, we achieved a (3)He polarization of 76% ± 1% and maintained it for the entire three-day duration of the test experiment. Based on transmission measurements with unpolarized neutrons, we show that the average analyzing efficiency of the (3)He system is 98% for the neutron wavelength band of 2-5 Å. Using a highly polarized incident neutron beam produced by a supermirror bender polarizer, we obtained a flipping ratio of >100 with a transmission of 25% for polarized neutrons, averaged over the wavelength band of 2-5 Å. After the cell was depolarized for transmission measurements, it was reproducibly polarized and this performance was maintained for three weeks. A high quality polarization analysis experiment was performed on a reference sample of Fe/Cr multilayer with strong spin-flip off-specular scattering. Using a combination of the position sensitive detector, time-of-flight method, and the excellent parameters of the (3)He cell, the polarization analysis of the two-dimensional maps of reflected, refracted, and off-specular scattered intensity above and below the horizon were obtained, simultaneously.
13. Diode-Pumped Mode-Locked LiSAF Laser; FINAL
International Nuclear Information System (INIS)
None
1996-01-01
Under this contract we have developed Cr(sup 3+):LiSrAlF(sub 6) (Cr:LiSAF, LiSAF) mode-locked lasers suitable for generation of polarized electrons for CEBAF. As 670 nm is an excellent wavelength for optical pumping of Cr:LiSAF, we have used a LIGHTWAVE developed 670 nm diode pump module that combines the output of ten diode lasers and yields approximately 2 Watts of optical power. By the use of a diffraction limited pump beam however, it is possible to maintain a small mode size through the length of the crystal and hence extract more power from Cr:LiSAF laser. For this purpose we have developed a 1 Watt, red 660nm laser (LIGHTWAVE model 240R) which serves as an ideal pump for Cr:LiSAF and is a potential replacement of costly and less robust krypton laser. This new system is to compliment LIGHTWAVE Series 240, and is currently being considered for commercialization. Partially developed under this contract is LIGHTWAVEs product model 240 which has already been in our production lines for a few months and is commercially available. This laser produces 2 Watts of output at 532 nm using some of the same technology developed for production of the 660nm red system. It is a potential replacement for argon ion lasers and has better current and cooling requirements and is an excellent pump source for Ti:Al(sub 2)O(sub 3). Also, as a direct result of this contract we now have the capability of commercially developing a mode-locked 100MHz Cr:LiSAF system. Such a laser could be added to our 100 MHz LIGHTWAVE Series 131. The Series 131 lasers provide pico second pulses and were originally developed under another DOE SBIR. Both models of LIGHTWAVE Series 240 lasers, the fiber coupled pump module and the 100MHz LiSAF laser of Series 131 have been partially developed under this contract, and are commercially competitive products
14. CW lasing of Ho in KLu(WO4)2 in-band pumped by a diode-pumped Tm:KLu(WO4)2 laser.
Science.gov (United States)
Mateos, Xavier; Jambunathan, Venkatesan; Pujol, Maria Cinta; Carvajal, Joan Josep; Díaz, Francesc; Aguiló, Magdalena; Griebner, Uwe; Petrov, Valentin
2010-09-27
We demonstrate continuous wave (CW) room temperature laser operation of the monoclinic Ho(3+)-doped KLu(WO(4))(2) crystal using a diode-pumped Tm(3+):KLu(WO(4))(2) laser for in-band pumping. The slope efficiency achieved amounts to ~55% with respect to the absorbed power and the maximum output power of 648 mW is generated at 2078 nm.
15. The 3He spectral function in light-front dynamics
Directory of Open Access Journals (Sweden)
Rinaldi Matteo
2016-01-01
Full Text Available A distorted spin-dependent spectral function for 3He is considered for the extraction of the transverse-momentum dependent parton distributions in the neutron from semi-inclusive deep inelastic electron scattering off polarized 3He at finite momentum transfers, where final state interactions are taken into account. The generalization of the analysis to a Poincaré covariant framework within the light-front dynamics is outlined.
16. 110 GHz rapid, continous tuning from an optical parametric oscillator pumped by a fiber-amplified DBR diode laser
NARCIS (Netherlands)
Lindsay, I.D.; Adhimoolam, B.; Gross, P.; Klein, M.E.; Boller, Klaus J.
2005-01-01
A singly-resonant continuous-wave optical parametric oscillator (cw-OPO) pumped by a fiber-amplified diode laser is described. Tuning of the pump source allowed the OPO output to be tuned continuously, without mode-hops, over 110 GHz in 29 ms. Discontinuous pump tuning over 20 nm in the region of
17. Passive Q switching of a solar-pumped Nd:YAG laser.
Science.gov (United States)
Lando, M; Shimony, Y; Noter, Y; Benmair, R M; Yogev, A
2000-04-20
Passive Q switching is a preferable choice for switching the Q factor of a solar-pumped laser because it requires neither a driver nor an electrical power supply. The superior thermal characteristics and durability of Cr(4+):YAG single crystals as passive Q switches for lamp and diode-pumped high-power lasers has been demonstrated. Here we report on an average power of 37 W and a switching efficiency of 80% obtained by use of a solar-pumped Nd:YAG laser Q switched by a Cr(4+):YAG saturable absorber. Concentration of the pumping solar energy on the laser crystal was obtained with a three-stage concentrator, composed of 12 heliostats, a three-dimensional compound parabolic concentrator (CPC) and a two-dimensional CPC. The water-cooled passive Q switch also served as the laser rear mirror. Repetition rates of as much as 50 kHz, at pulse durations between 190 and 310 ns (FWHM) were achieved. From the experimental results, the saturated single-pass power absorption of the Cr(4+):YAG device was estimated as 3 ? 1%.
18. Mid-infrared optical parametric oscillator pumped by an amplified random fiber laser
Science.gov (United States)
Shang, Yaping; Shen, Meili; Wang, Peng; Li, Xiao; Xu, Xiaojun
2017-01-01
Recently, the concept of random fiber lasers has attracted a great deal of attention for its feature to generate incoherent light without a traditional laser resonator, which is free of mode competition and insure the stationary narrow-band continuous modeless spectrum. In this Letter, we reported the first, to the best of our knowledge, optical parametric oscillator (OPO) pumped by an amplified 1070 nm random fiber laser (RFL), in order to generate stationary mid-infrared (mid-IR) laser. The experiment realized a watt-level laser output in the mid-IR range and operated relatively stable. The use of the RFL seed source allowed us to take advantage of its respective stable time-domain characteristics. The beam profile, spectrum and time-domain properties of the signal light were measured to analyze the process of frequency down-conversion process under this new pumping condition. The results suggested that the near-infrared (near-IR) signal light inherited' good beam performances from the pump light. Those would be benefit for further develop about optical parametric process based on different pumping circumstances.
19. Comparison of fiber lasers based on distributed side-coupled cladding-pumped fibers and double-cladding fibers.
Science.gov (United States)
Huang, Zhihe; Cao, Jianqiu; Guo, Shaofeng; Chen, Jinbao; Xu, Xiaojun
2014-04-01
We compare both analytically and numerically the distributed side-coupled cladding-pumped (DSCCP) fiber lasers and double cladding fiber (DCF) lasers. We show that, through optimization of the coupling and absorbing coefficients, the optical-to-optical efficiency of DSCCP fiber lasers can be made as high as that of DCF lasers. At the same time, DSCCP fiber lasers are better than the DCF lasers in terms of thermal management.
20. Bragg-Scattering Four-Wave Mixing in Nonlinear Fibers with Intracavity Frequency-Shifted Laser Pumps
Directory of Open Access Journals (Sweden)
Katarzyna Krupa
2012-01-01
Full Text Available We experimentally study four-wave mixing in highly nonlinear fibers using two independent and partially coherent laser pumps and a third coherent signal. We focus our attention on the Bragg-scattering frequency conversion. The two pumps were obtained by amplifying two Intracavity frequency-shifted feedback lasers working in a continuous wave regime.
1. Characteristics of a laser beam produced by using thermal lensing effect compensation in a fiber-coupled laser-diode-pumped Nd:YAG ceramic laser
International Nuclear Information System (INIS)
Kim, Duck-Lae; Kim, Byung-Tai
2010-01-01
The characteristics of a laser beam produced by using thermal lensing effect compensation in a fiber-coupled laser-diode Nd:YAG ceramic laser were investigated. The thermal lensing effect was compensated for by using a compensator, which was 25 mm away from the laser rod, with a focal length of 30 mm and an effective clear aperture of 22 mm. Using a compensator, the divergence and the beam propagation factor M 2 of the output beam were 5.5 mrad and 2.4, respectively, under a pump power of 12W. The high-frequency components in the compensated laser beam were removed.
2. Polarized 3He gas circulating technologies for neutron analyzers
Energy Technology Data Exchange (ETDEWEB)
Watt, David W. [Xemed, LLC, Durham, NH (United States)
2017-10-02
with asymptotic to 45 percent, which was below expectations. This low value resulted from a stationary thermal inversion in the cell that caused most of the laser power to be absorbed near the laser inlet window and deprived the lower portions of the cell of pumping laser light. Possible solutions to this problem include enhanced cooling of the cell near the laser entry and slight detuning of the laser. 6. Ongoing work. Our polarizer development efforts are ongoing to pursue our interest in neutron analyzers, nuclear targets, and providing helium for medical imaging. Current tests in the pipeline include: 1. Testing cooling enhancements to improve laser penetration of spectrally narrow lasers; 2. Testing of a cell with isolation valves that minimizes diffusive contact with gas handling hardware during polarization; 3. Testing of smaller hybrid cells with reduced alkali loading; 4. Producing polarized helium-3 for MRI imaging at the University of Missouri.
3. A twin optically-pumped far-infrared CH3OH laser for plasma diagnostics
International Nuclear Information System (INIS)
Yamanaka, M.; Takeda, Y.; Tanigawa, S.; Nishizawa, A.; Noda, N.
1979-11-01
A twin optically-pumped far-infrared CH 3 OH laser has been constructed for use in plasma diagnostics. The anti-symmetric doublet due to the Raman-type resonant two-photon transition is reproducibly observed at 118.8 μm. With the 118.8-μm line, it is obtained from the frequency separation of the anti-symmetric doublet that the CH 3 OH absorption line center is 16 +- 1 MHz higher than the pump 9.7-μm P(36) CO 2 laser line center. It is shown that the Raman-type resonant two-photon transition is useful in order to get several-MHz phase modulation for the far-infrared laser interferometer. Some preliminary performances of this twin laser for the modulated interferometer are described. (author)
4. A solar simulator-pumped gas laser for the direct conversion of solar energy
Science.gov (United States)
Weaver, W. R.; Lee, J. H.
1981-01-01
Most proposed space power systems are comprised of three general stages, including the collection of the solar radiation, the conversion to a useful form, and the transmission to a receiver. The solar-pumped laser, however, effectively eliminates the middle stage and offers direct photon-to-photon conversion. The laser is especially suited for space-to-space power transmission and communication because of minimal beam spread, low power loss over large distances, and extreme energy densities. A description is presented of the first gas laser pumped by a solar simulator that is scalable to high power levels. The lasant is an iodide C3F7I that as a laser-fusion driver has produced terawatt peak power levels.
5. Twin optically-pumped far-infrared CH3OH laser for plasma diagnostics
International Nuclear Information System (INIS)
Yamanaka, M.; Takeda, Y.; Tanigawa, S.; Nishizawa, A.
1980-01-01
A twin optically-pumped far-infrared CH 3 OH laser has been constructed for use in plasma diagnostics. The antisymmetric doublet due to the Raman-type resonant two-photon transition is reproducibly observed at 118.8 microns. With the 118.8-micron line, it is found that CH 3 OH absorption line center is 16 + or - 1 MHz higher than the pump 9.7-micron P(36) CO 2 laser line center. It is shown that the Raman-type resonant two-photon transition is useful in order to get several MHz phase modulation for the far-infrared laser interferometer. Some preliminary performances of this twin laser for the modulated interferometer are described
6. High Efficient LGp0 End Pumped Nd:YAG Laser
CSIR Research Space (South Africa)
Ngcobo, S
2012-07-01
Full Text Available the slope efficiency of the laser due to the increased in the fundamental mode volume of the laser. The beam shaping is achieved by using an annular binary Diffractive Optical Element whose geometry is in connection with the location of the Laguerre...
7. Thermally induced diffraction losses for a Gaussian pump beam and optimization of the mode-to-pump ratio in an end-pumped Nd:GdVO4 laser
International Nuclear Information System (INIS)
Wang, Y T; Li, W J; Pan, L L; Yu, J T; Zhang, R H
2013-01-01
The analytical model of thermally induced diffraction losses for a Gaussian pump beam are derived as functions of the mode-to-pump ratio and pump power in end-pumped Nd-doped lasers considering the energy transfer upconversion effects. The mode-to-pump ratio is optimized based on it. The results show that the optimum mode-to-pump ratio with the thermally induced diffraction losses is less than 0.65, and it is less than the results in which the thermally induced diffraction losses are neglected. The theoretical model is applied to a diode-end-pumped Nd:GdVO 4 laser operating at 1342 nm, and the theoretical calculations are in good agreement with the experimental results. (paper)
8. Polarized 3He Gas Circulating Technologies for Neutron Analyzers
Energy Technology Data Exchange (ETDEWEB)
Watt, David [Xemed LLC, Durham, NH (United States); Hersman, Bill [Xemed LLC, Durham, NH (United States)
2014-12-10
We describe the development of an integrated system for quasi-continuous operation of a large volume neutron analyzer. The system consists of a non-magnetic diaphragm compressor, a prototype large volume helium polarizer, a surrogate neutron analyzer, a non-depolarizing gas storage reservoir, a non-ferrous valve manifold for handling gas distribution, a custom rubidium-vapor gas return purifier, and wire-wound transfer lines, all of which are immersed in a two-meter external magnetic field. Over the Phase II period we focused on three major tasks required for the successful deployment of these types of systems: 1) design and implementation of gas handling hardware, 2) automation for long-term operation, and 3) improvements in polarizer performance, specifically fabrication of aluminosilicate optical pumping cells. In this report we describe the design, implementation, and testing of the gas handling hardware. We describe improved polarizer performance resulting from improved cell materials and fabrication methods. These improvements yielded valved 8.5 liter cells with relaxation times greater than 12 hours. Pumping this cell with 1500W laser power with 1.25nm linewidth yielded peak polarizations of 60%, measured both inside and outside the polarizer. Fully narrowing this laser to 0.25nm, demonstrated separately on one stack of the four, would have allowed 70% polarization with this cell. We demonstrated the removal of 5 liters of polarized helium from the polarizer with no measured loss of polarization. We circulated the gas through a titanium-clad compressor with polarization loss below 3% per pass. We also prepared for the next phase of development by refining the design of the polarizer so that it can be engineer-certified for pressurized operation. The performance of our system far exceeds comparable efforts elsewhere.
9. 80-W cw TEM{sub 00} IR beam generation by use of a laser-diode-side-pumped Nd:YAG rod laser
Energy Technology Data Exchange (ETDEWEB)
Konno, Susumu; Fujikawa, Shuichi; Yasui, Koji [Mitsubishi Electric Corp. Amagasaki, Hyogo (Japan). Advanced Technology R and D Center
1998-03-01
We have demonstrated high-efficient and high-power operation of a diode-side-pumped Nd:YAG rod laser. The laser has a simple and scalable configuration consisting of a diffusive pumping reflector and an advanced cavity configuration for polarization-dependent bifocusing compensation. (author)
10. Effect of Cr4+ impurities in Nd:Cr:GSGG and Nd:Cr:YAG laser materials on parameters of lasers at solar pumping
International Nuclear Information System (INIS)
Payziyev, Sh.D.; Bakhramov, S.A.; Shayimov, F.F.; Fayziev, A.Sh.
2015-01-01
The analysis of an effect of Cr 4+ impurity ions, existent in Nd 3+ :Cr 3+ :GSGG and Nd 3+ :Cr 3+ :YAG laser materials on output parameters of solar pumped lasers is carried out by modeling of lasing process at solar pumping. (authors)
11. Laser cavities with self-pumped phase conjugation by mixing of four waves in an amplifier
International Nuclear Information System (INIS)
Sillard, Pierre
1998-01-01
The purpose of this research thesis is to characterise a new type of cavities with self-pumped phase conjugation which uses a mixing of four waves degenerated in a solid amplifier. After a definition of phase conjugation and a brief overview of the history of this technique, the author describes and compares the different laser architectures with phase conjugation. He explains benefits and perspectives related to cavities with self-pumped phase conjugation using a mixing of four waves in an amplifier. He develops the necessary formalism for the resolution of the coupled equations of four wave mixing in transient regime for a resonant and saturated non-linearity. He shows how these results can be applied to solid amplifiers, in particularly to the Nd:YAG amplifier which is used in all experiments. In the next part, the author describes the principle and characteristics of cavity with self-pumped phase conjugation injected by another laser. An experiment is performed with two conventional Nd:YAG amplifiers pumped by flash lamps. The excellent performance of the cavity allows the study of cavity without this injection, but self-oscillating is to be envisaged, and a modelling of self-oscillating cavities is proposed and studied. Results are compared with those obtained with two N:YAG amplifiers pumped by flash lamps. Polarisation properties of the self-oscillating cavity are also studied. Finally, the author reports an experimental validation of a cavity with self-pumped phase conjugation all in solid state, pumped by laser diodes (a more efficient pumping) [fr
12. Design of high-brightness TEM00-mode solar-pumped laser for renewable material processing
Science.gov (United States)
Liang, D.; Almeida, J.
2014-08-01
The conversion of sunlight into laser light by direct solar pumping is of ever-increasing importance because broadband, temporally constant, sunlight is converted into laser light, which can be a source of narrowband, collimated, rapidly pulsed, radiation with the possibility of obtaining extremely high brightness and intensity. Nonlinear processes, such as harmonic generation, might be used to obtain broad wavelength coverage, including the ultraviolet wavelengths, where the solar flux is very weak. The direct excitation of large lasers by sunlight offers the prospect of a drastic reduction in the cost of coherent optical radiation for high average power materials processing. This renewable laser has a large potential for many applications such as high-temperature materials processing, renewable magnesium-hydrogen energy cycle and so on. We propose here a scalable TEM00 mode solar laser pumping scheme, which is composed of four firststage 1.13 m diameter Fresnel lenses with its respective folding mirrors mounted on a two-axis automatic solar tracker. Concentrated solar power at the four focal spots of these Fresnel lenses are focused individually along a common 3.5 mm diameter, 70 mm length Nd:YAG rod via four pairs of second-stage fused-silica spherical lenses and third-stage 2D-CPCs (Compound Parabolic Concentrator), sitting just above the laser rod which is also double-pass pumped by four V-shaped pumping cavities. Distilled water cools both the rod and the concentrators. 15.4 W TEM00 solar laser power is numerically calculated, corresponding to 6.7 times enhancement in laser beam brightness.
13. A diode-pumped Tm:YAG laser with an elliptical cavity mode
International Nuclear Information System (INIS)
Lipnicki, E.; Dawes, J.M.; Browne, P.G.
2000-01-01
Full text: A cavity consisting of cylindrical mirrors/lenses resulting in an elliptical cavity mode is being applied to a 3-level laser; Tm:YAG which lases near 2μm. This arrangement allows the use of simple pump beam optics but also ensures efficient mode matching with good output beam quality. This cavity has been designed and modelled with experiments under way to explore the advantages of this laser design
14. Self-Q-switched ytterbium-doped cladding-pumped fibre laser
International Nuclear Information System (INIS)
Grukh, Dmitrii A; Kurkov, Andrei S; Razdobreev, I M; Fotiadi, A A
2002-01-01
A self-Q-switched ytterbium-doped double-clad fibre laser is described. A samarium-doped fibre is used as a filter for protecting a pump source. A fibre coupler is employed to obtain a nonlinear feedback. The mechanism of pulse formation in the laser is considered, and the dependence of its output pulse on the coupler parameters is studied. (solitons and optical fibers)
15. High-power extended cavity laser optimized for optical pumping ot Rb
Czech Academy of Sciences Publication Activity Database
Buchta, Zdeněk; Číp, Ondřej; Lazar, Josef
2007-01-01
Roč. 18, č. 9 (2007), N77-N80 ISSN 0957-0233 R&D Pro jects: GA ČR GA102/04/2109; GA MŠk(CZ) LC06007; GA AV ČR IAA200650504; GA AV ČR IAA1065303 Institutional research plan: CEZ:AV0Z20650511 Keywords : laser diode * emission linewidth * diffraction grating * optical pumping * spectroscopy Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.297, year: 2007
16. High-speed off-axis holographic cinematography with a copper-vapor-pumped dye laser.
Science.gov (United States)
Lauterborn, W; Judt, A; Schmitz, E
1993-01-01
A series of coherent light pulses is generated by pumping a dye laser with the pulsed output of a copper-vapor laser at rates of as much as 20 kHz. Holograms are recorded at this pulse rate on a rotating holographic plate. This technique of high-speed holographic cinematography is demonstrated by viewing the bubble filaments that appear in water under the action of a sound field of high intensity.
17. Development of a compact in situ polarized 3He neutron spin filter at Oak Ridge National Laboratory
International Nuclear Information System (INIS)
Jiang, C. Y.; Tong, X.; Brown, D. R.; Kadron, B. J.; Robertson, J. L.; Chi, S.; Christianson, A. D.; Winn, B. L.
2014-01-01
We constructed a compact in situ polarized 3 He neutron spin filter based on spin-exchange optical pumping which is capable of continuous pumping of the 3 He gas while the system is in place in the neutron beam on an instrument. The compact size and light weight of the system simplifies its utilization on various neutron instruments. The system has been successfully tested as a neutron polarizer on the triple-axis spectrometer (HB3) and the hybrid spectrometer (HYSPEC) at Oak Ridge National Laboratory. Over 70% 3 He polarization was achieved and maintained during the test experiments. Over 90% neutron polarization and an average of 25% transmission for neutrons of 14.7 meV and 15 meV was also obtained
18. Production of d, t, 3He, anti d, anti t and anti 3He by 200 GeV protons
International Nuclear Information System (INIS)
Bozzoli, W.; Giacomelli, G.; Rimondi, F.; Zylberajch, S.; Lesquoy, E.; Meunier, R.; Moscoso, L.; Muller, A.; Bussiere, A.
1978-01-01
Data are presented on the yields of d, t, 3 He, anti d, anti t, and anti 3 He with laboratory momenta between 12 and 37 GeV/c produced by 200 GeV protons on beryllium and aluminium. The production yield of nuclei depends significantly on the target nucleus, while the anti d production is independent of target material. The mass dependence of the production cross section is exponential for both nuclei and antinuclei
19. Analysis of Nd3+:glass, solar-pumped, high-powr laser systems
Science.gov (United States)
Zapata, L. E.; Williams, M. D.
1989-01-01
The operating characteristics of Nd(3+):glass lasers energized by a solar concentrator were analyzed for the hosts YAG, silicate glass, and phosphate glass. The modeling is based on the slab zigzag laser geometry and assumes that chemical hardening methods for glass are successful in increasing glass hardness by a factor of 4. On this basis, it was found that a realistic 1-MW solar-pumped laser might be constructed from phosphate glass 4 sq m in area and 2 mm thick. If YAG were the host medium, a 1-MW solar-pumped laser need only be 0.5 sq m in area and 0.5 cm thick, which is already possible. In addition, Nd(3+) doped glass fibers were found to be excellent solar-pumped laser candidates. The small diameter of fibers eliminates thermal stress problems, and if their diameter is kept small (10 microns), they propagate a Gaussian single mode which can be expanded and transmitted long distances in space. Fiber lasers could then be used for communications in space or could be bundled and the individual beams summed or phase-matched for high-power operation.
20. Temperature effects on tunable cw Alexandrite lasers under diode end-pumping.
Science.gov (United States)
Kerridge-Johns, William R; Damzen, Michael J
2018-03-19
Diode pumped Alexandrite is a promising route to high power, efficient and inexpensive lasers with a broad (701 nm to 858 nm) gain bandwidth; however, there are challenges with its complex laser dynamics. We present an analytical model applied to experimental red diode end-pumped Alexandrite lasers, which enabled a record 54 % slope efficiency with an output power of 1.2 W. A record lowest lasing wavelength (714 nm) and record tuning range (104 nm) was obtained by optimising the crystal temperature between 8 °C and 105 °C in the vibronic mode. The properties of Alexandrite and the analytical model were examined to understand and give general rules in optimising Alexandrite lasers, along with their fundamental efficiency limits. It was found that the lowest threshold laser wavelength was not necessarily the most efficient, and that higher and lower temperatures were optimal for longer and shorter laser wavelengths, respectively. The pump excited to ground state absorption ratio was measured to decrease from 0.8 to 0.7 by changing the crystal temperature from 10 °C to 90 °C.
1. Cw and Q-switched Nd:NaLa(MoO4)2 laser noncritical to the temperature drift of the diode pump laser wavelength
International Nuclear Information System (INIS)
Ushakov, S N; Lis, Denis A; Subbotin, Kirill A; Romanyuk, V A; Shestakov, A V; Ryabochkina, P A; Shestakova, I A; Zharikov, Evgeny V
2010-01-01
Lasing in Nd:NaLa(MoO 4 ) 2 crystals is obtained without stabilisation of the diode pump wavelength. A dependence of the cw laser power (at a wavelength of 1059 nm) on the pump diode temperature is found within a range of 10-458C. It is shown that the variations in the diode temperature within this region change the lasing efficiency no more than by 30%. In the passive Q-switching regime, the experiments were performed under both pulsed and cw pumping. Upon pulsed pumping, the laser energy was 16 μJ at the output pulse duration of 11 ns. The laser wavelength was 1059 nm, as well as in the case of cw operation. Upon cw pumping with a power of 1.5 W, laser pulses were obtained with an energy of 15 μJ. (lasers)
2. Primary populations of metastable antiprotonic $^{4}He$ and $^{3}He$ atoms
CERN Document Server
Hori, Masaki; Hayano, R S; Ishikawa, T; Sakuguchi, J; Tasaki, T; Widmann, E; Yamaguchi, H; Torii, H A; Juhász, B; Horváth, D; Yamazaki, T
2002-01-01
Initial population distributions of metastable antiprotonic **4He and **3He atoms over principal and angular momentum quantum numbers were investigated using laser spectroscopy. The total fractions of antiprotons captured into the metastable states of the atoms were deduced. Cascade calculations were performed using the measure populations to reproduce the delayed annihilation time spectrum. Results showed agreement between the simulated and measured spectra. (Edited abstract) 30 Refs.
3. Electrically pumped graphene-based Landau-level laser
Science.gov (United States)
Brem, Samuel; Wendler, Florian; Winnerl, Stephan; Malic, Ermin
2018-03-01
Graphene exhibits a nonequidistant Landau quantization with tunable Landau-level (LL) transitions in the technologically desired terahertz spectral range. Here, we present a strategy for an electrically driven terahertz laser based on Landau-quantized graphene as the gain medium. Performing microscopic modeling of the coupled electron, phonon, and photon dynamics in such a laser, we reveal that an inter-LL population inversion can be achieved resulting in the emission of coherent terahertz radiation. The presented paper provides a concrete recipe for the experimental realization of tunable graphene-based terahertz laser systems.
4. In situ SEOP polarised {sup 3}He neutron spin filter for incident beam polarisation and polarisation analysis on neutron scattering instruments
Energy Technology Data Exchange (ETDEWEB)
Boag, S., E-mail: [email protected] [ISIS, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Babcock, E. [Institut Laue-langevin, 6 rue J. horowitz, BP 156, 38042, Grenoble Cedex 9 (France); Juelich Centre for Neutron Science at FRM II, Lichtenbergstrae 1, 85747 Garching (Germany); Andersen, K.H.; Becker, M. [Institut Laue-langevin, 6 rue J. horowitz, BP 156, 38042, Grenoble Cedex 9 (France); Charlton, T.R. [ISIS, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Chen, W.C. [National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899 (United States); Dalgliesh, R.M.; Elmore, S.D.; Frost, C.D. [ISIS, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Gentile, T.R. [National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899 (United States); Lopez Anton, R. [ISIS, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); ICMA, CSIC-Universidad de Zaragoza, Zaragoza 50009 (Spain); Parnell, S.R. [Academic Unit of Radiology, University of Sheffield, S10 2JF (United Kingdom); Petoukhov, A.K. [Institut Laue-langevin, 6 rue J. horowitz, BP 156, 38042, Grenoble Cedex 9 (France); Skoda, M.W.A. [ISIS, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Soldner, T. [Institut Laue-langevin, 6 rue J. horowitz, BP 156, 38042, Grenoble Cedex 9 (France)
2009-09-01
We discuss the development and characterisation of a new in situ spin exchange optical pumping (SEOP) based {sup 3}He neutron spin filter polarisation device. We present results from a recent test of the prototype system developed with the Institut Laue-Langevin. The polariser was installed on the polarised reflectometer CRISP at ISIS in the analyser position. The {sup 3}He was pumped continuously in situ on the beamline. The system also integrated a {sup 3}He adiabatic fast passage spin flipper that allowed reversal of the {sup 3}He and therefore neutron polarisation state, allowing for measurement of all four polarisation cross-sections. The system was run for a number of days reaching a {sup 3}He polarisation of 63%.
5. First results from Tyrex, the new polarized-3He filling station at ILL
International Nuclear Information System (INIS)
Andersen, K.H.; Chung, R.; Guillard, V.; Humblot, H.; Jullien, D.; Lelievre-Berna, E.; Petoukhov, A.; Tasset, F.
2005-01-01
A new filling station for nuclear polarisation of 3 He gas has been constructed at the ILL, Grenoble. The 'Tyrex' machine uses metastability-exchange optical pumping for polarising the 3 He gas at about 1 mbar pressure. The gas is then compressed up to several bars via a hydraulic titanium-alloy piston compressor. The machine can provide about 1.5 bar-l/h of polarised gas--an order-of-magnitude increase over the first filling station installed at the ILL in 1996. The compressed, polarised gas is used for polarising neutron beams for condensed-matter and fundamental physics experiments. First results are presented and examples of implementations on existing neutron instruments at ILL are described
6. Combined He3 cryostats and He3-He4 dilution refrigerators
International Nuclear Information System (INIS)
Kovac, L.; Balla, J.
1974-07-01
A modular set of equipment was designed, which consists of a 4 He Dewar vessel with a very low evaporation rate, having a pumped 4 He bath in which either a 3 He cryostat or a dilution refrigerator within removable inserts can be placed. Any of them can be simply and rapidly connected to the versatile Dewar, auxiliary 4 He-, vacuum; and 3 He- 4 He systems. Two such sets have already been completed and can be used at temperatures from 1.5K to 0.05K for thermodynamic and neutron diffraction measurements. The performance of all inserts was stable and reliable, differences between the cryostats and runs were small - nearly all within the accuracy of temperature determination. The construction of a lot of parts is identical, allowing rapid manufacture. Assembling and repairs are simple, all parts are easily accessible. (K.A.)
7. A new type of liquid-3He target system using small mechanical refrigerators
International Nuclear Information System (INIS)
Kato, S.; Kobayashi, K.; Maruyama, K.; Okuno, H.; Konno, O.; Suda, T.; Maki, T.; Asami, H.; Koizumi, T.
1991-04-01
A new type of liquid- 3 He target has been developed for photoabsorption experiments at intermediate energies. Using the cooling power of liquid 4 He at reduced vapour pressure, 3 He gas is liquefied into a cylindrical target cell of 180 ml and is maintained at 2.0 K during the experiment. Evaporated 4 He gas is evacuated by a rotary pump and returned into the 4 He bath in the cryostat, where two small mechanical refrigerators with cooling capacities of 3 W at 4.3 K and 10 W at 20 K are operated for the purpose of 4 He recondensation. A maintenance-free operation of more than 1,000 hours has become possible by adopting the 4 He circulation system. (author)
8. Large-area high-power VCSEL pump arrays optimized for high-energy lasers
Science.gov (United States)
Wang, Chad; Geske, Jonathan; Garrett, Henry; Cardellino, Terri; Talantov, Fedor; Berdin, Glen; Millenheft, David; Renner, Daniel; Klemer, Daniel
2012-06-01
Practical, large-area, high-power diode pumps for one micron (Nd, Yb) as well as eye-safer wavelengths (Er, Tm, Ho) are critical to the success of any high energy diode pumped solid state laser. Diode efficiency, brightness, availability and cost will determine how realizable a fielded high energy diode pumped solid state laser will be. 2-D Vertical-Cavity Surface-Emitting Laser (VCSEL) arrays are uniquely positioned to meet these requirements because of their unique properties, such as low divergence circular output beams, reduced wavelength drift with temperature, scalability to large 2-D arrays through low-cost and high-volume semiconductor photolithographic processes, high reliability, no catastrophic optical damage failure, and radiation and vacuum operation tolerance. Data will be presented on the status of FLIR-EOC's VCSEL pump arrays. Analysis of the key aspects of electrical, thermal and mechanical design that are critical to the design of a VCSEL pump array to achieve high power efficient array performance will be presented.
9. Investigations of Laser Pumped Gas Cell Atomic Frequency Standard
National Research Council Canada - National Science Library
Volk, C. H; Camparo, J. C; Frueholz, R. P
1981-01-01
Recently it has been suggested that the performance characteristics of a rubidium gas cell atomic frequency standard might be improved by replacing the standard rubidium discharge lamp with a single mode laser diode...
10. End-pumped Nd:YVO4 laser with reduced thermal lensing via the use of a ring-shaped pump beam.
Science.gov (United States)
Lin, Di; Andrew Clarkson, W
2017-08-01
A simple approach for alleviating thermal lensing in end-pumped solid-state lasers using a pump beam with a ring-shaped intensity distribution to decrease the radial temperature gradient is described. This scheme has been implemented in a diode-end-pumped Nd:YVO 4 laser yielding 14 W of TEM 00 output at 1.064 μm with a corresponding slope efficiency of 53% and a beam propagation factor (M 2 ) of 1.08 limited by available pump power. By comparison, the same laser design with a conventional quasi-top-hat pump beam profile of approximately equal radial extent yielded only 9 W of output before the power rolled over due to thermal lensing. Further investigation with the aid of a probe beam revealed that the thermal lens power was ∼30% smaller for the ring-shaped pump beam compared to the quasi-top-hat beam. The implications for further power scaling in end-pumped laser configurations are considered.
11. Design of LD in-band direct-pumping side surface polished micro-rod Nd:YVO4 laser
International Nuclear Information System (INIS)
Zhang Wen-Qi; Wang Fei; Liu Qiang; Gong Ma-Li
2016-01-01
To diminish the thermal load, two ways, that is, in-band direct pumping and micro-rod crystal, could be adopted at the same time. The efficiency of LD in-band direct-pumping side surface polished micro-rod Nd:YVO 4 laser is numerically analyzed. By optimizing parameters such as crystal length, laser mode radius, pump beam radius, doping concentration and crystal cross-section size, the overall efficiency can reach over 50%. It is found that with micro-rod crystal implemented in the laser oscillator, high overall efficiency LD in-band direct-pumping Nd:YVO 4 laser could be realized. High efficiency combined with low thermal load makes this laser an outstanding scheme for building high-power Nd:YVO 4 lasers. (paper)
12. Flashlamp pumped Ti-sapphire laser for ytterbium glass chirped pulse amplification
Energy Technology Data Exchange (ETDEWEB)
Nishimura, Akihiko; Ohzu, Akira; Sugiyama, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; and others
1998-03-01
A flashlamp pumped Ti:sapphire laser is designed for ytterbium glass chirped pulse amplification. A high quality Ti:sapphire rod and a high energy long pulse discharging power supply are key components. The primary step is to produce the output power of 10 J per pulse at 920 nm. (author)
13. Investigation into diode pumped modelocked Nd based laser oscillators for the CLIC-3 photoinjector system
NARCIS (Netherlands)
Valentine, G.J.; Burns, D.; Bente, E.A.J.M.; Berghmans, F.; Thienpont, H.; Danckaert, J.; Desmet, L.
2001-01-01
The photo-injector system envisaged for the proposed CLIC linear e+-e- accelerator at CERN has a demanding set of specifications on output pulse structure, power and timing stability. This paper reports on results obtained with quasi-CW diode pumped laser oscillators with output stabilisation. A
14. About a fuel for burnup reactor of periodical pulsed nuclear pumped laser
International Nuclear Information System (INIS)
Volkov, A.I.; Lukin, A.V.; Magda, L.E.; Magda, E.P.; Pogrebov, I.S.; Putnikov, I.S.; Khmelnitsky, D.V.; Scherbakov, A.P.
1998-01-01
A physical scheme of burnup reactor for a Periodic Pulsed Nuclear Pumped Laser was supposed. Calculations of its neutron physical parameters were made. The general layout and construction of basic elements of the reactor are discussed. The requirements for the fuel and fuel elements are established. (author)
15. New class of compact diode pumped sub 10 fs lasers for biomedical applications
DEFF Research Database (Denmark)
Le, T.; Mueller, A.; Sumpf, B.
2016-01-01
Diode-pumping Ti: sapphire lasers promises a new approach to low-cost femtosecond light sources. Thus in recent years much effort has been taken just to overcome the quite low power and low beam qualities of available green diodes to obtain output powers of several hundred milliwatts from a fs-la...
16. Side-pumped Nd:YVO4 cw laser with grazing-incidence small angle configuration
International Nuclear Information System (INIS)
Camargo, Fabiola de Almeida
2006-01-01
Within the existing variety of laser cavity geometries and gain materials there is one combination that is particularly interesting because of its reduced complexity and high efficiency: the edge-pumped slab-laser using grazing-incidence geometry and a gain media with a very high pump absorption cross-section. In this work we studied a diode side-pumped Nd:YVO 4 cw laser. We describe a single and a multiple bounce laser configurations. We demonstrate 22 W of multimode output power for 35 watts of pump power with a single pass through the gain media. A high optical-to-optical conversion efficiency of 63% and a slope efficiency of 74% with a very compact and simple Nd:YVO 4 cavity that uses joint stability zones was achieved. The beam quality was M 2 = 26 x 11 in the horizontal and vertical direction, respectively. With a double pass configuration we achieved 17 watts with a better beam quality of M 2 = 3,4 x 3,7, in the horizontal and vertical direction, respectively. (author)
17. Orientation of Ar(3P2) atoms by laser optical pumping
International Nuclear Information System (INIS)
Giberson, K.W.; Hart, M.W.; Hammond, M.S.; Dunning, F.B.; Walters, G.K.
1984-01-01
A beam of argon metastable atoms with a high degree of electron-spin polarization has been produced by optical pumping using an Oxazine 750 dye laser. The beam is suitable for the study of electron spin and orbital orientation dependences in a variety of collision processes
18. Rapidly tunable continuous-wave optical parametric oscillator pumped by a fiber laser
NARCIS (Netherlands)
Klein, M.E.; Gross, P.; Boller, Klaus J.; Auerbach, M.; Wessels, P.; Fallnich, C.
2003-01-01
We report on rapid, all-electronically controlled wavelength tuning of a continuous-wave (cw) optical parametric oscillator (OPO) pumped by an ytterbium fiber laser. The OPO is singly resonant for the signal wave and consists of a 40-mm-long periodically poled lithium niobate crystal in a
19. Thermal lensing effects in cw-pumped Nd3: YAG laser rods
International Nuclear Information System (INIS)
Chang, C.
Thermal lensing effects were investigated in cw-pumped Nd 3+ : YAG laser rods. For identically specified rods very different thermally induced focal lengths were measured. Thus compensation of thermal lensing by applying curved end faces should be done individually for each rod. (orig.) 891 HT/orig. 892 HIS
20. Diode-end-pumped Tm:GdVO4 laser operating at 1818 and 1915 nm
CSIR Research Space (South Africa)
Esser, MJD
2009-10-01
Full Text Available wavelengths. We therefore embarked on ac- curately measuring absorption spectra of Tm:GdVO4 laser crystals at both 0.8 (pump band) and at 1.9 µm (emission band). The measurements were conducted with a Cary 5000 spectrometer with resolution set to 1 nm...
1. Picosecond transient backward stimulated Raman scattering and pumping of femtosecond dye lasers
Science.gov (United States)
Arrivo, Steven M.; Spears, Kenneth G.; Sipior, Jeffrey
1995-02-01
We report studies of transient, backward stimulated, Raman scattering (TBSRS) in solvents with a 10 Hz, 27 ps, 532 nm pump laser. The TBSRS effect was used to create pulses at 545 nm and 630 nm with durations of 2-3 ps and 5-10 μJ of energy. The duration, energy and fluctuations of the Raman pulse were studied as a function of pump energy and focal parameters. A 5 μJ Raman pulse was amplified in either a Raman amplifier or two stage dye amplifier to 1 mJ levels. A 545 nm pulse of 3 ps duration was generated in CCl 4 and was then used to pump a short cavity dye laser (SCDL). The SCDL oscillator and a 5 stage dye amplifier provided a pulse of 700 fs and 400 μJ that was tunable near 590 nm.
2. 1018 nm Yb-doped high-power fiber laser pumped by broadband pump sources around 915 nm with output power above 100 W
DEFF Research Database (Denmark)
Midilli, Yakup; Efunbajo, Oyewole Benjamin; Şimşek, Bartu
2017-01-01
laser were also addressed in this study. Finally, we have tested this system for high power experimentation and obtained 67% maximum optical-to-optical efficiency at an approximately 110 W output power level. To the best of our knowledge, this is the first 1018 nm ytterbium-doped all-fiber laser pumped...
3. PUMPS
Science.gov (United States)
Thornton, J.D.
1959-03-24
A pump is described for conveving liquids, particure it is not advisable he apparatus. The to be submerged in the liquid to be pumped, a conduit extending from the high-velocity nozzle of the injector,and means for applying a pulsating prcesure to the surface of the liquid in the conduit, whereby the surface oscillates between positions in the conduit. During the positive half- cycle of an applied pulse liquid is forced through the high velocity nozzle or jet of the injector and operates in the manner of the well known water injector and pumps liquid from the main intake to the outlet of the injector. During the negative half-cycle of the pulse liquid flows in reverse through the jet but no reverse pumping action takes place.
4. Optically pumped semiconductor lasers: Conception and characterization of a single mode source for Cesium atoms manipulation
International Nuclear Information System (INIS)
Cocquelin, B.
2009-02-01
Lasers currently used in atomic clocks or inertial sensors are suffering from a lack of power, narrow linewidth or compactness for future spatial missions. Optically pumped semiconductor lasers, which combine the approach of classical solid state lasers and the engineering of semiconductor laser, are considered here as a candidate to a metrological laser source dedicated to the manipulation of Cesium atoms in these instruments. These lasers have demonstrated high power laser emission in a circular single transverse mode, as well as single longitudinal mode emission, favoured by the semiconductor structure and the external cavity design. We study the definition and the characterization of a proper semiconductor structure for the cooling and the detection of Cesium atoms at 852 nm. A compact and robust prototype tunable on the Cesium D2 hyperfine structure is built. The laser frequency is locked to an atomic transition thanks to a saturated absorption setup. The emission spectral properties are investigated, with a particular attention to the laser frequency noise and the laser linewidth. Finally, we describe and model the thermal properties of the semiconductor structure, which enables the simulation of the laser power characteristic. The experimental parameters are optimised to obtain the maximum output power with our structure. Thanks to our analysis, we propose several ways to overcome these limitations, by reducing the structure heating. (authors)
5. The copper-pumped dye laser system at Lawrence Livermore National Laboratory
International Nuclear Information System (INIS)
Hackel, R.P.; Warner, B.E.
1993-01-01
The Lawrence Livermore National Laboratory's (LLNL) Atomic Vapor Laser Isotope Separation (AVLIS) Program has developed a high-average-power, pulsed, tunable, visible laser system. Testing of this hardware is in progress at industrial scale. The LLNL copper-dye laser system is prototypical of a basic module of a uranium-AVLIS plant. The laser demonstration facility (LDF) system consists of copper vapor lasers arranged in oscillator-amplifier chains providing optical pump power to dye-laser master-oscillator-power-amplifier chains. This system is capable of thousands of watts (average) tunable between 550 and 650 mm. The copper laser system at LLNL consists of 12 chains operating continuously. The copper lasers operate at nominally 4.4 kHz, with 50 ns pulse widths and produce 20 W at near the diffraction limit from oscillators and >250 W from each amplifier. Chains consist of an oscillator and three amplifiers and produce >750 W average, with availabilities >95% (i.e., >8,300 h/y). The total copper laser system power averages ∼9,000 W and has operated at over 10,000 W for extended intervals. The 12 copper laser beams are multiplexed and delivered to the dye laser system where they pump multiple dye laser chains. Each dye chain consists of a master oscillator and three or four power amplifiers. The master oscillator operates at nominally 100 mW with a 50 MHz single mode bandwidth. Amplifiers are designed to efficiently amplify the dye beam with low ASE content and high optical quality. Sustained dye chain powers are up to 1,400 W with dye conversion efficiency >50%, ASE content <5%, and wavefront quality correctable to <λ/10 RMS, using deformable mirrors. Since the timing of the copper laser chains can be offset, the dye laser system is capable of repetition rates which are multiples of 4.4 kHz, up to 26 kHz, limited by the dye pumping system. Development of plant-scale copper and dye laser hardware is progressing in off-line facilities
6. Anomalous dependence of the lasing parameters of dye solutions on the spectrum of microsecond pump laser pulses
International Nuclear Information System (INIS)
Tarkovsky, V V; Kurstak, V Yu; Anufrik, S S
2003-01-01
The anomalous dependence of the lasing parameters of ethanol solutions of coumarin, rhodamine, oxazine, and laser dyes of other classes on the spectrum of microsecond pump laser pulses is found. The dependence is determined by the shape of the induced singlet - singlet absorption spectra and absorption spectra of short-lived photoproducts. The elucidation of the influence of these factors makes it possible to choose optimal pump spectra and to enhance the efficiency and stability of microsecond dye lasers. (active media)
7. 20 W continuous-wave cladding-pumped Nd-doped fiber laser at 910 nm.
Science.gov (United States)
Laroche, M; Cadier, B; Gilles, H; Girard, S; Lablonde, L; Robin, T
2013-08-15
We demonstrate a double-clad fiber laser operating at 910 nm with a record power of 20 W. Laser emission on the three-level scheme is enabled by the combination of a small inner cladding-to-core diameter ratio and a high brightness pump source at 808 nm. A laser conversion efficiency as high as 44% was achieved in CW operating regime by using resonant fiber Bragg reflectors at 910 nm that prevent the lasing at the 1060 nm competing wavelength. Furthermore, in a master oscillator power-amplifier scheme, an amplified power of 14.8 W was achieved at 914 nm in the same fiber.
8. Femtosecond Laser--Pumped Source of Entangled Photons for Quantum Cryptography Applications
International Nuclear Information System (INIS)
Pan, D.; Donaldson, W.; Sobolewski, R.
2007-01-01
We present an experimental setup for generation of entangled-photon pairs via spontaneous parametric down-conversion, based on the femtosecond-pulsed laser. Our entangled-photon source utilizes a 76-MHz-repetition-rate, 100-fs-pulse-width, mode-locked, ultrafast femtosecond laser, which can produce, on average, more photon pairs than a cw laser of an equal pump power. The resulting entangled pairs are counted by a pair of high-quantum-efficiency, single-photon, silicon avalanche photodiodes. Our apparatus s intended as an efficient source/receiver system for the quantum communications and quantum cryptography applications
9. Amplification of UV ultrashort pulse laser in e-beam pumped KrF amplifier
CERN Document Server
Tang Xiu Zhang; Gong Kun; Ma Wei Yi; Shan Yu Sheng; Wang Nai Yan
2002-01-01
Experimental investigations were performed for amplification of ultrashort pulse laser with Heaven-I e-beam pumped KrF amplifier in CIAE. A 50 mJ, 420 fs UV ultrashort pulse was amplified to 2-3 J energy, 1.2 ps pulse duration, and 2TW laser power. Experimental technique such as synchronization were describe, some parameters such as nonlinear absorb coefficient were measured in experiment. As a result, it is possible to achieve ultra-strong UV laser with intensity higher than 10 sup 1 sup 9 W/cm sup 2 in recently years
10. Nanoimprinted organic semiconductor laser pumped by a light-emitting diode.
Science.gov (United States)
Tsiminis, Georgios; Wang, Yue; Kanibolotsky, Alexander L; Inigo, Anto R; Skabara, Peter J; Samuel, Ifor D W; Turnbull, Graham A
2013-05-28
An organic semiconductor laser, simply fabricated by UV-nanoimprint lithography (UV-NIL), that is pumped with a pulsed InGaN LED is demonstrated. Molecular weight optimization of the polymer gain medium on a nanoimprinted polymer distributed feedback resonator enables the lowest reported UV-NIL laser threshold density of 770 W cm(-2) , establishing the potential for scalable organic laser fabrication compatible with mass-produced LEDs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
11. Amplification of UV ultrashort pulse laser in e-beam pumped KrF amplifier
International Nuclear Information System (INIS)
Tang Xiuzhang; Zhang Haifeng; Gong Kun; Ma Weiyi; Shan Yusheng; Wang Naiyan
2002-01-01
Experimental investigations were performed for amplification of ultrashort pulse laser with Heaven-I e-beam pumped KrF amplifier in CIAE. A 50 mJ, 420 fs UV ultrashort pulse was amplified to 2-3 J energy, 1.2 ps pulse duration, and 2TW laser power. Experimental technique such as synchronization were describe, some parameters such as nonlinear absorb coefficient were measured in experiment. As a result, it is possible to achieve ultra-strong UV laser with intensity higher than 10 19 W/cm 2 in recently years
12. High-power diode-side-pumped intracavity-frequency-doubled continuous wave 532 nm laser
International Nuclear Information System (INIS)
Zhang Yuping; Zhang Huiyun; Zhong Kai; Li Xifu; Wang Peng; Yao Jianquan
2007-01-01
An efficient and high-power diode-side-pumped cw 532 nm green laser based on a V-shaped cavity geometry, and capable of generating 22.7 W green radiation with optical conversion efficiency of 8.31%, has been demonstrated. The laser is operated with rms noise amplitude of less than 1% and with M 2 -parameter of about 6.45 at the top of the output power. This laser has the potential for scaling to much higher output power. (authors)
13. Backward pumping kilowatt Yb3+-doped double-clad fiber laser
Science.gov (United States)
Han, Z. H.; Lin, X. C.; Hou, W.; Yu, H. J.; Zhou, S. Z.; Li, J. M.
2011-09-01
A ytterbium-doped double-clad fiber laser generating up to 1026 W of continuous-wave output power at 1085 nm with a slope efficiency of 74% by single-ended backward pumping configuration is reported. The core diameter was 20 μm with a low numerical aperture of 0.06, and a good beam quality (BPP < 1.8 mm mrad) is achieved without special mode selection methods. No undesirable roll-over was observed in output power with increasing pump power, and the maximum output power was limited by the available pump power. The instability of maximum output power was better than ±0.6%. Different pumping configurations were also compared in experiment, which shows good agreements with theoretical analyses.
14. Dynamics of phase-separated 3He-4He films
International Nuclear Information System (INIS)
Kurihara, Susumu
1982-01-01
A froehlich-type Hamiltonian is derived for third sound and 3 He quasi particles in phase-separated double layer of superfluid 4 He and normal 3 He liquid. It is stressed that our system is unique and valuable in that characteristic parameters can be varied in a wide range, simply by adjusting the film thickness. The effect of fermion-boson coupling on the velocity and damping of the third sound is examined. It is predicted that a rather drastic change in the third sound spectrum will occur when the Fermi velocity of 3 He system and the third sound velocity are nearly the same. It is pointed out that the system under consideration may show a variety of interesting phenomena, in addition to the softening of the third sound. (author)
15. Physics analysis of the Apollo D-3He tokamak reactor
International Nuclear Information System (INIS)
Santarius, J.F.; Emmert, G.A.
1990-01-01
Recent developments in the analysis and conceptual design of Apollo, a D- 3 He Tokamak Reactor are presented. Encouraging experimental results on TEXT motivated a key change in the Apollo concept utilization of an ergodic magnetic limiter for impurity control instead of a divertor. Parameters for the updated Apollo design and an analysis of the ergoidc magnetic limiter are given. The Apollo reference case uses direct conversion of synchrotron radiation to electricity by rectifying antennas (rectennas) for its power conversion system. Previous analyses of this concept are expanded, including further details of the rectennas and of the loss of synchrotron power to the waveguides and walls. Although Apollo will burn D- 3 He fuel, a significant amount of unburned tritium will be generated by D4D reactions. The possibility of operating a short, dedicated, T+ 3 He burn phase to eliminate this tritium will be examined
16. Development of solar concentrators for high-power solar-pumped lasers.
Science.gov (United States)
Dinh, T H; Ohkubo, T; Yabe, T
2014-04-20
We have developed unique solar concentrators for solar-pumped solid-state lasers to improve both efficiency and laser output power. Natural sunlight is collected by a primary concentrator which is a 2 m×2 m Fresnel lens, and confined by a cone-shaped hybrid concentrator. Such solar power is coupled to a laser rod by a cylinder with coolant surrounding it that is called a liquid light-guide lens (LLGL). Performance of the cylindrical LLGL has been characterized analytically and experimentally. Since a 14 mm diameter LLGL generates efficient and uniform pumping along a Nd:YAG rod that is 6 mm in diameter and 100 mm in length, 120 W cw laser output is achieved with beam quality factor M2 of 137 and overall slope efficiency of 4.3%. The collection efficiency is 30.0 W/m2, which is 1.5 times larger than the previous record. The overall conversion efficiency is more than 3.2%, which can be comparable to a commercial lamp-pumped solid-state laser. The concept of the light-guide lens can be applied for concentrator photovoltaics or other solar energy optics.
17. High efficiency pump combiner fabricated by CO2 laser splicing system
Science.gov (United States)
Zhu, Gongwen
2018-02-01
High power combiners are of great interest for high power fiber lasers and fiber amplifiers. With the advent of CO2 laser splicing system, power combiners are made possible with low manufacturing cost, low loss, high reliability and high performance. Traditionally fiber optical components are fabricated with flame torch, electrode arc discharge or filament heater. However, these methods can easily leave contamination on the fiber, resulting inconsistent performance or even catching fire in high power operations. The electrodes or filaments also degrade rapidly during the combiner manufacturing process. The rapid degradation will lead to extensive maintenance, making it unpractical or uneconomic for volume production. By contrast, CO2 laser is the cleanest heating source which provides reliable and repeatable process for fabricating fiber optic components including high power combiners. In this paper we present an all fiber end pumped 7x1 pump combiner fabricated by CO2 laser splicing system. The input pump fibers are 105/125 (core/clad diameters in μm) fibers with a core NA of 0.22. The output fiber is a 300/320 fiber with a core NA of 0.22. The average efficiency is 99.4% with all 7 ports more than 99%. The process is contamination-free and highly repeatable. To our best knowledge, this is the first report in the literature on power combiners fabricated by CO2 laser splicing system. It also has the highest reported efficiency of its kind.
18. Aerosol core nuclear reactor for space-based high energy/power nuclear-pumped lasers
International Nuclear Information System (INIS)
Prelas, M.A.; Boody, F.P.; Zediker, M.S.
1987-01-01
An aerosol core reactor concept can overcome the efficiency and/or chemical activity problems of other fuel-reactant interface concepts. In the design of a laser using the nuclear energy for a photon-intermediate pumping scheme, several features of the aerosol core reactor concept are attractive. First, the photon-intermediate pumping concept coupled with photon concentration methods and the aerosol fuel can provide the high power densities required to drive high energy/power lasers efficiently (about 25 to 100 kW/cu cm). Secondly, the intermediate photons should have relatively large mean free paths in the aerosol fuel which will allow the concept to scale more favorably. Finally, the aerosol core reactor concept can use materials which should allow the system to operate at high temperatures. An excimer laser pumped by the photons created in the fluorescer driven by a self-critical aerosol core reactor would have reasonable dimensions (finite cylinder of height 245 cm and radius of 245 cm), reasonable laser energy (1 MJ in approximately a 1 millisecond pulse), and reasonable mass (21 kg uranium, 8280 kg moderator, 460 kg fluorescer, 450 kg laser medium, and 3233 kg reflector). 12 references
19. Diode pumped actively Q-switched Nd:YVO4 self-Raman laser
International Nuclear Information System (INIS)
Su Fufang; Zhang Xingyu; Wang Qingpu; Ding Shuanghong; Jia Peng; Li Shutao; Fan Shuzhen; Zhang Chen; Liu Bo
2006-01-01
By using Nd:YVO 4 as the gain medium and the Raman medium simultaneously, the actively Q-switched operation of the self-Raman Nd:YVO 4 laser at 1176 nm was realized. The output characteristics including the average power, pulse energy and pulse width versus the incident pump power and pulse repetition rate were investigated. At a pulse repetition rate of 20 kHz an average power up to 0.57 W was obtained with the incident pump power of 10.2 W, corresponding to a conversion efficiency of 5.6% with respect to the diode laser input power. Meanwhile, an analysis of the self-Raman Nd:YVO 4 laser was carried out by using the rate equations. The obtained theoretical results were in agreement with the experimental results on the whole
20. Diode-side-pumped 131 W, 1319 nm single-wavelength cw Nd:YAG laser.
Science.gov (United States)
Haiyong, Zhu; Ge, Zhang; Chenghui, Huang; Yong, Wei; Lingxiong, Huang; Jing, Chen; Weidong, Chen; Zhenqiang, Chen
2007-01-20
A diode-side-pumped high-power 1319 nm single-wavelength Nd:YAG continuous wave (cw) laser is described. Through reasonable coating design of the cavity mirrors, the 1064 nm strongest line as well as the 1338 nm one have been successfully suppressed. The laser output powers corresponding to four groups of different output couplers operating at 1319 nm single wavelength have been compared. The output coupler with the transmission T=5.3% has the highest output power, and a 131 W cw output power was achieved at the pumping power of 555 W. The optical-optical conversion efficiency is 23.6%, and the slope efficiency is 46%. The output power is higher than the total output power of the dual-wavelength laser operating at 1319 nm and 1338 nm in the experiment.
1. System of laser pump and synchrotron radiation probe microdiffraction to investigate optical recording process
International Nuclear Information System (INIS)
Yasuda, Nobuhiro; Fukuyama, Yoshimitsu; Osawa, Hitoshi; Kimura, Shigeru; Ito, Kiminori; Tanaka, Yoshihito; Matsunaga, Toshiyuki; Kojima, Rie; Hisada, Kazuya; Tsuchino, Akio; Birukawa, Masahiro; Yamada, Noboru; Sekiguchi, Koji; Fujiie, Kazuhiko; Kawakubo, Osamu; Takata, Masaki
2013-01-01
We have developed a system of laser-pump and synchrotron radiation probe microdiffraction to investigate the phase-change process on a nanosecond time scale of Ge 2 Sb 2 Te 5 film embedded in multi-layer structures, which corresponds to real optical recording media. The measurements were achieved by combining (i) the pump-laser system with a pulse width of 300 ps, (ii) a highly brilliant focused microbeam with wide peak-energy width (ΔE/E ∼ 2%) made by focusing helical undulator radiation without monochromatization, and (iii) a precise sample rotation stage to make repetitive measurements. We successfully detected a very weak time-resolved diffraction signal by using this system from 100-nm-thick Ge 2 Sb 2 Te 5 phase-change layers. This enabled us to find the dependence of the crystal-amorphous phase change process of the Ge 2 Sb 2 Te 5 layers on laser power.
2. Diode-pumped Kerr-lens mode-locked femtosecond Yb:YAG ceramic laser
Science.gov (United States)
Zi-Ye, Gao; Jiang-Feng, Zhu; Ke, Wang; Jun-Li, Wang; Zhao-Hua, Wang; Zhi-Yi, Wei
2016-02-01
We experimentally demonstrated a diode-pumped Kerr-lens mode-locked femtosecond laser based on an Yb:YAG ceramic. Stable laser pulses with 97-fs duration, 2.8-nJ pulse energy, and 320-mW average power were obtained. The femtosecond oscillator operated at a central wavelength of 1049 nm and a repetition rate of 115 MHz. To the best of our knowledge, this is the first demonstration of a Kerr-lens mode-locked operation in a diode-pumped Yb:YAG ceramic laser with sub-100 fs pulse duration. Project supported by the National Major Scientific Instrument Development Project of China (Grant No. 2012YQ120047), the National Natural Science Foundation of China (Grant No. 61205130), and the Fundamental Research Funds for the Central Universities, China (Grant No. JB140502).
3. Hyperfine spectrum measurement of an optically pumped far-infrared laser with a Michelson interferometer
International Nuclear Information System (INIS)
Zuo, Z G; Ling, F R; Wang, P; Liu, J S; Yao, J Q; Weng, C X
2013-01-01
In this letter, we present a Michelson interferometer for the hyperfine spectrum measurement of an optically pumped far-infrared laser with a highest frequency resolution of 3–5 GHz. CH 3 OH gas with a purity of 99.9%, is pumped by the CO 2 9P36 and 9R10 laser lines to generate terahertz lasers with frequencies of 2.52 and 3.11 THz, respectively. Moreover, except for the center frequency, which is in good agreement with theoretical work, some additional frequencies on both sides of the center frequency are obtained at a frequency interval of 0.15 THz. Meanwhile, the mechanism behind the observed experimental results is also investigated. (letter)
4. Development of diode-pumped solid-state laser HALNA for fusion reactor driver
International Nuclear Information System (INIS)
Kawashima, Toshiyuki; Kanabe, Tadashi; Matsumoto, Osamu
2005-01-01
The diode-pumped slab laser for inertial fusion energy driver has been demonstrated, which produces the 1053-nm output energy of 10 J at 10 Hz. The glass slab laser amplifier has been pumped by quasi-CW 290 kW AlGaAs laser-diode arrays at 803 nm. The optical system can compensate for thermal effects by use of zig-zag optical propagation, image-relayed telescope, and 45deg Faraday rotator. The output energy of 10.6 J at 1 Hz with the optical to optical conversion efficiency of 19.9% has been successfully obtained. Also the 10 Hz operation has been performed with a 5.1 J output energy. (author)
5. Removing gaseous contaminants in 3He by cryogenic stripping
International Nuclear Information System (INIS)
Benapfl, M.; Biltoft, P.; Coombs, A.
1995-01-01
The Tritium Operations Group at LLNL, Tritium Facility has recently developed a 3 He recovery system to remove argon, xenon, neon, hydrogen, and all other contaminants from the 3 He stream in an Accelerator Production of Tritium (APT) experimental apparatus. In this paper the authors will describe in detail the background information, technical requirements, the design approach, and the results of their experimental tests. The authors believe this gas purification system may have other applications as it provides at a reasonable cost an efficient method for purification of gaseous helium
6. The SLAC high-density gaseous polarized 3He target
International Nuclear Information System (INIS)
Johnson, J.R.; Chupp, T.E.; Smith, T.B.; Cates, G.D.; Driehuys, B.; Middleton, H.; Newbury, N.R.; Hughes, E.W.; Meyer, W.
1995-01-01
A large-scale high-pressure gaseous 3 He polarized target has been developed for use with a high-intensity polarized electron beam at the Stanford Linear Accelerator Center. This target was used successfully in an experiment to study the spin structure of the neutron. The target provided an areal density of about 7x10 21 nuclei/cm 2 and operated at 3 He polarizations between about 30% and 40% for the six-week duration of the experiment. ((orig.))
7. Dissipation of flow in superfluid 3He-A
International Nuclear Information System (INIS)
Paalanen, M.A.; Osheroff, D.D.
1980-01-01
The first direct measurements of the dissipation due to flow are performed and the effects of that flow on the NMR properties of 3 He-A are studied. A temperature-independent critical velocity v/sub c/=0.52 mm/s is observed, above which a pressure difference proportional to v/sub s/-v/sub c/ developes across our flow orifice. simultaneously, the NMR frequency in 3 He-A is lowered by an amount also proportional to v/sub s/-v/sub c/, in contrast to current theoretical predictions
8. Surface study of liquid 3He using surface state electrons
International Nuclear Information System (INIS)
Shirahama, K.; Ito, S.; Suto, H.; Kono, K.
1995-01-01
We have measured the mobility of surface state electrons (SSE) on liquid 3 He, μ 3 , aiming to study the elementary surface excitations of the Fermi liquid. A gradual increase of μ 3 below 300 mK is attributed to the scattering of electrons by ripplons. Ripplons do exist in 3 He down to 100 mK. We observe an abrupt decrease of μ 3 , due to the transition to the Wigner solid (WS). The dependences of the WS conductivity and mobility on temperature and magnetic field differ from the SSE behavior on liquid 4 He
9. Δ excitation in 3He and 4He by photons
International Nuclear Information System (INIS)
Maruyama, Koichi.
1993-06-01
The use of the 3 He and 4 He photodisintegration reactions in the study of the excitation, propagation, and decay of the Δ (1232) in these nuclei is proposed. By using the data obtained with TAGX for both photon absorption on neutron-proton pairs and complete photodisintegration, we find no compelling evidence for the change of the Δ property in the 3 He and 4 He nuclei. It is also proposed to use nuclear photodisintegration in the search for the excitation of the higher-mass nucleon resonances whose absence in the total photon-absorption cross sections in nuclei is reported recently. (author)
10. Real squashing mode in textures in 3He-B
International Nuclear Information System (INIS)
Mineev, V.P.
1985-01-01
The shape of the absorption line of ultrasound due to various components of the real squashing mode in textures in 3 He-B is investigated. An explanation is presented of the additional splitting of the absorption line for the M=0 component of the real squashing model in a magnetic field and of the absence of such splitting of lines with M=+-1, +-2 in the case of place geometry. The peculiarities of the shape of the ultrasound absorption lines for various components of the real squashing mode in a rotating cylindrical vessel with 3 He-B are discussed
11. Laser pumping of ions in a cooler buncher
Energy Technology Data Exchange (ETDEWEB)
Cheal, B., E-mail: [email protected] [University of Manchester (United Kingdom); Baczynska, K. [University of Birmingham, School of Physics and Astronomy (United Kingdom); Billowes, J.; Campbell, P. [University of Manchester (United Kingdom); Eronen, T. [University of Jyvaeskylae, Department of Physics (Finland); Forest, D. H. [University of Birmingham, School of Physics and Astronomy (United Kingdom); Kessler, T.; Moore, I. D. [University of Jyvaeskylae, Department of Physics (Finland); Rueffer, M. [University of Birmingham, School of Physics and Astronomy (United Kingdom); Tordoff, B. [University of Manchester (United Kingdom); Tungate, G. [University of Birmingham, School of Physics and Astronomy (United Kingdom); Aystoe, J. [University of Jyvaeskylae, Department of Physics (Finland)
2008-01-15
Optical experiments at the IGISOL isotope separator facility, Jyvaeskylae, have for many years benefited from the introduction of an ion beam cooler. The device, a gas-filled RF quadrupole, reduces the emittance and longitudinal energy spread of the ion beam. Very recently, use has been made of the axial confinement of slowly travelling ions at the end of the cooler to redistribute the electronic populations through efficient laser excitation. Such a technique has proved beneficial to laser spectroscopic measurements and is a precursor to using the method to polarize the ion beam.
12. Studies of diode-pumped solid-state lasers based on Nd:KGW and Nd:YAG
International Nuclear Information System (INIS)
Ibrahim, Akram Yousif
1996-01-01
The experimental part of the thesis was dedicated to the studies of diode-pumped solid- state lasers. it includes experiments with end-pumped continuous wave (CW) Nd-doped crystals. In particular, we have concentrated to Nd:KGW, a relatively new and not studied in the literature about the laser materials. We have performed some basics measurements of this material. A fibre bundle coupled laser diode array was used as a pump source. We have investigated two main optical arrangements for the pump, allowing operation in two regimes: 1- Low pump power operation using selected output power from a single of the fibre bundle. 2- high pump power operation using the total output power from the bundle. The main parameters of the cavities we use (e.g. the cavity mode and the pumping spot size), were determined using the matrix approach and the equations for the propagation of the Gaussian beams. The highest output power obtained in this work for Nd:KGW with a transverse electromagnetic (TEM 0 0) single-mode, continuous (CW) operation, was 400 mW for 1700 mW pumping power from the diode laser. We present also data about the performance of a diode pumped Nd:YAG crystal. Our experiment shows that Nd:KGW is a promising material of low and medium pumping power levels. (Author)
13. 1.8kW laser diode pumped YAG laser; Shutsuryoku 1.8kW no handotai laser reiki YAG laser
Energy Technology Data Exchange (ETDEWEB)
NONE
1999-03-01
Toshiba Corporation, as a participant in Ministry of International Trade and Industrys photon measurement and processing technology project since August, 1997, is engaged in the development of an energy-efficient LD (laser diode) pumped semiconductor YAG (yttrium-aluminum-garnet) laser device to be used for welding and cutting. It is a 5-year project and the goal is a mean output of 10kW and efficiency of 20%. In this article, a simulation program is developed which carries out calculation about element technology items such as the tracking of the beam from the pumping LD and the excitation distribution, temperature distribution, thermal stress distribution, etc., in the YAG rod. An oscillator is constructed, based on the results of the simulation, and it exhibits a world-high class continuous laser performance of a 1.8kW output and 13% efficiency. The record of 13% efficiency is five times higher than that achieved by the conventional lamp-driven YAG laser device. (translated by NEDO)
14. Simulation of medical Q-switch flash-pumped Er:YAG laser
Energy Technology Data Exchange (ETDEWEB)
Wang Yanlin; Huang Chuyun; Yao Yucheng; Zou Xiaolin, E-mail: [email protected], E-mail: [email protected], E-mail: [email protected], E-mail: [email protected] [Physics school, Hubei University of Technology, Wuhan, China 430068 (China)
2011-01-01
Er: YAG laser, the wavelength is 2940nm, can be absorbed strongly by water. The absorption coefficient is as high as 13000 cm{sup -1}. As the water strong absorption, Erbium laser can bring shallow penetration depth and smaller surrounding tissue injury in most soft tissue and hard tissue. At the same time, the interaction between 2940nm radiation and biological tissue saturated with water is equivalent to instantaneous heating within limited volume, thus resulting in the phenomenon of micro-explosion to removal organization. Different parameters can be set up to cut enamel, dentin, caries and soft tissue. For the development and optimization of laser system, it is a practical choice to use laser modeling to predict the influence of various parameters for laser performance. Aim at the status of low Erbium laser output power, flash-pumped Er: YAG laser performance was simulated to obtain optical output in theory. the rate equation model was obtained and used to predict the change of population densities in various manifolds and use the technology of Q-switch the simulate laser output for different design parameters and results showed that Er: YAG laser output energy can achieve the maximum average output power of 9.8W under the given parameters. The model can be used to find the potential laser systems that meet application requirements.
15. 3He flow in dilute 3He-4He mixtures at temperatures between 10 and 150 mK
International Nuclear Information System (INIS)
Castelijns, C.A.M.; Kuerten, J.G.M.; de Waele, A.T.A.M.; Gijsman, H.M.
1985-01-01
The mutual friction between 3 He and 4 He II below 150 mK has been studied. Empirical relations for the adiabatic and the nonadiabatic flow properties of 3 He moving through 4 He have been determined using a dilution refrigerator with a single mixing chamber. The validity of the relations is verified by osmotic-pressure measurements and by measuring the properties of a double-mixing-chamber system. It is shown that superleak shunts have a strong effect on the flow characteristics. From the nonadiabatic flow properties an expression is derived for the mutual-friction-force density between 3 He and 4 He II. This has a strong resemblance to the Gorter-Mellink mutual-friction-force density between the normal and the superfluid components in pure 4 He II. It is speculated that the 3 He flow in our systems generates a 4 He vortex tangle, which leads to the observed mutual friction between 3 He and 4 He and also to a strong clamping of the 4 He to the walls
16. Pump spot size dependent lasing threshold in organic semiconductor DFB lasers fabricated via nanograting transfer.
Science.gov (United States)
Liu, Xin; Klinkhammer, Sönke; Wang, Ziyao; Wienhold, Tobias; Vannahme, Christoph; Jakobs, Peter-Jürgen; Bacher, Andreas; Muslija, Alban; Mappes, Timo; Lemmer, Uli
2013-11-18
Optically excited organic semiconductor distributed feedback (DFB) lasers enable efficient lasing in the visible spectrum. Here, we report on the rapid and parallel fabrication of DFB lasers via transferring a nanograting structure from a flexible mold onto an unstructured film of the organic gain material. This geometrically well-defined structure allows for a systematic investigation of the laser threshold behavior. The laser thresholds for these devices show a strong dependence on the pump spot diameter. This experimental finding is in good qualitative agreement with calculations based on coupled-wave theory. With further investigations on various DFB laser geometries prepared by different routes and based on different organic gain materials, we found that these findings are quite general. This is important for the comparison of threshold values of various devices characterized under different excitation areas.
17. Pump spot size dependent lasing threshold in organic semiconductor DFB lasers fabricated via nanograting transfer
DEFF Research Database (Denmark)
Liu, Xin; Klinkhammer, Sönke; Wang, Ziyao
2013-01-01
material. This geometrically well-defined structure allows for a systematic investigation of the laser threshold behavior. The laser thresholds for these devices show a strong dependence on the pump spot diameter. This experimental finding is in good qualitative agreement with calculations based on coupled......Optically excited organic semiconductor distributed feedback (DFB) lasers enable efficient lasing in the visible spectrum. Here, we report on the rapid and parallel fabrication of DFB lasers via transferring a nanograting structure from a flexible mold onto an unstructured film of the organic gain......-wave theory. With further investigations on various DFB laser geometries prepared by different routes and based on different organic gain materials, we found that these findings are quite general. This is important for the comparison of threshold values of various devices characterized under different...
18. Ultraviolet-pumped liquid-crystal dye-laser
International Nuclear Information System (INIS)
Bertolotti, M.; Sbrolli, L.; Scudieri, F.; Papa, T.
1981-01-01
The possibility offered by the orientation properties of liquid crystals as a matrix for dye lasers is shown. In particular, the linear polarization of emitted light can be changed by acting with an external magnetic field on the molecular nematic director. (author)
19. The electrodisintegration of 3He studied with the 3He(e,e'p)2H and 3He(e,e'd)1H reactions
International Nuclear Information System (INIS)
Keizer, P.H.M.
1986-01-01
The author presents a survey of experimental and theoretical results for the ground-state properties of 3 He. The formalism of the (e,e'p) and (e,e'd) reactions is presented. A short description of the instrumentation, in particular those elements which are typical for the present study, and of the data analysis is given. This includes a description of the elements required in the 'recoil detection' technique. The kinematics of the experiments and the results are presented. The results are discussed and compared with calculations. (Auth.)
20. Compact, efficient diode-end-pumped Nd:GdVO4 slab continuous-wave 912-nm laser
International Nuclear Information System (INIS)
Liu Huan; Gong Ma-Li
2012-01-01
A fiber-coupled laser-diode (LD) end-pumped Nd:GdVO 4 slab continuous-wave (CW) 912-nm laser and an LD bar end-pumped Nd:GdVO 4 slab CW 912-nm laser are both demonstrated in this paper. Using the fiber-coupled LD of end-pumped type, a highest CW 912-nm laser output power of 10.17 W is obtained with a high optical-to-optical conversion efficiency of 24.6% and a slope efficiency of 34.5%. The measured M 2 factors of beam quality in x and y directions are 5.3 and 5.1, respectively. Besides, an LD bar of end-pumped type is used to realize CW 912-nm laser output, which has the advantages of compactness and low cost. When the pump power is 38.8 W, the output power is 8.87 W and the measured M 2 factors of beam quality in x and y directions are 16 and 1.31, respectively. In order to improve the beam quality of the 912-nm laser at x direction, a new quasi-concentric laser resonator will be designed, and an LD bar end-pumped Nd:GdVO 4 slab high-power CW 912-nm TEM 00 laser will be realized in the future. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
1. Ignition access in a D-3He helical reactor
International Nuclear Information System (INIS)
Mitarai, Osamu
2003-01-01
Ignition access in a D- 3 He helical reactor is studied based on 0-dimensional particle and power balance equations for deuterium, tritium, helium-3, alpha ash, proton ash, electron density and temperature. The calculations are based on the following experimental facts observed in LHD. (author)
2. Isospin effects in anti p3He annihilation at rest
International Nuclear Information System (INIS)
Balestra, F.; Barbieri, R.; Batusov, Yu.A.; Bendiscioli, G.; Breivik, F.O.; Bossolasco, S.; Bussa, M.P.; Busso, L.; Falomkin, I.V.; Ferrero, L.; Guaraldo, C.; Haatuft, A.; Halsteinslid, A.; Jacobsen, T.; Lodi Rizzini, E.; Maggiora, A.; Myklebost, K.; Olsen, J.M.; Panzieri, D.; Piragino, G.; Pontecorvo, G.B.; Rozhdestvensky, A.M.; Rotondi, A.; Salvini, P.; Sapozhnikov, M.G.; Soerensen, S.O.; Tosello, F.; Tretyak, V.I.; Venaglioni, A.; Zenoni, A.
1989-01-01
The analysis of anti p 3 He annihilation events at rest (from the PS 179 experiment at LEAR) gives the value 0.467±0.035 for the ratio between the annihilation cross sections on n and on p. This low value indicates a strong isospin dependence of the anti NN amplitude in P wave. (orig.)
3. Digital signal processing for 3He proportional counters
International Nuclear Information System (INIS)
Takahashi, Hiroyuki; Kawarabayashi, Jun; Kurahashi, Tomohiko; Iguchi, Tetsuo; Nakazawa, Masaharu
1994-01-01
Numerical analysis of individual pulses from 3 He proportional counters has been performed. A parametric approach has been used for the identification of a charge particle track direction. Using area parameters, a clear separation of events was observed for the wall effect on a triton and a proton, respectively. ((orig.))
4. Conceptual design of D-3He FRC reactor 'ARTEMIS'
International Nuclear Information System (INIS)
Momota, H.; Ishida, A.; Kohzaki, Y.
1991-07-01
A comprehensive design study of the D- 3 He fueled field-reversed configuration (FRC) reactor 'ARTEMIS' is carried out for the purpose of proving its attractive characteristics and clarifying the critical issues for a commercial fusion reactor. The FRC burning plasma is stabilized and sustained in a steady equilibrium by means of a preferential trapping of D- 3 He fusion-produced energetic protons. A novel direct energy converter for 15MeV protons is also presented. On the bases of a consistent scenario of the fusion plasma production and simple engineering, a compact and simple reactor concept is presented. The design of the D- 3 He FRC power plant definitely offers the most attractive prospect for energy development. It is environmentally acceptable in view of radio-activity and fuel resources; and the estimated cost of electricity is low compared to a light water reactor. Critical issues concerning physics or engineering for the development of the D- 3 He FRC reactor are clarified. (author)
5. The {sup 3}He neutron-spin filter at ILL
Energy Technology Data Exchange (ETDEWEB)
Tasset, F; Heil, W; Humblot, H; Lelievre-Berna, E; Roberts, T [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)
1997-04-01
Neutron-Spin Filters (NSF) using gaseous polarised {sup 3}He have long been recognised as of enormous potential value in many polarised neutron-scattering applications and, accordingly, ILL started a development programme some years ago. This report gives an account of the present status of the project. (author). 13 refs.
6. Internal Magnus effects in superfluid 3He-A
International Nuclear Information System (INIS)
Salmelin, R.H.; Salomaa, M.M.; Mineev, V.P.
1989-01-01
Orbital angular momentum of the coherently aligned Cooper pairs in superfluid 3 He-A is encountered by an object immersed in the condensate. We evaluate the associated quasiparticle-scattering asymmetry experienced by a negative ion; this leads to a measureable, purely quantum-mechanical reactive force deflecting the ion's trajectory. Possible hydrodynamic Magnus effects are also discussed
7. Topological symmetry breakdown in cholesterics, nematics, and 3He
International Nuclear Information System (INIS)
Balachandran, A.P.; Lizzi, F.; Rodgers, V.G.J.
1984-01-01
Cholesterics, uniaxial and biaxial nematics, and the dipole-free A phase of superfluid 3 He are characterized by order parameters which are left invariant by suitable ''symmetry'' groups H. We show that in the presence of defects, the full group H may not be implementable on the states because of topological obstructions. Thus H is topologically broken in the presence of suitable defects
8. Diode-pumped, single frequency Nd:YLF laser for 60-beam OMEGA laser pulse-shaping system
International Nuclear Information System (INIS)
Okishev, A.V.; Seka, W.
1997-01-01
The operational conditions of the OMEGA pulse-shaping system require an extremely reliable and low-maintenance master oscillator. The authors have developed a diode-pumped, single-frequency, pulsed Nd:YLF laser for this application. The laser generates Q-switched pulses of ∼160-ns duration and ∼10-microJ energy content at the 1,053-nm wavelength with low amplitude fluctuations (<0.6% rms) and low temporal jitter (<7 ns rms). Amplitude and frequency feedback stabilization systems have been used for high long-term amplitude and frequency stability
9. Infrared spectra of 4HeH+, 4HeD+, 3HeH+, and 3HeD+
International Nuclear Information System (INIS)
Crofton, M.W.; Altman, R.S.; Haese, N.N.; Oka, T.
1989-01-01
Isotopic species of the HeH + molecular ion provide an excellent testing ground for studying isotopic dependence of vibration--rotation constants because of the small masses of He and H isotopes. We have observed infrared spectra of the hot band v=2 left-arrow 1 of HeH + and fundamental bands of isotopic species HeD + , 3 HeH + , and 3 HeD + , and obtained the Dunham coefficients Y kl , and the isotopically independent parameters U kl , Δ He kl , and Δ H kl
10. The OSIRIS diffractometer and polarisation analysis spectrometer at ISIS. New developments and 3He spin-filter polarisation analysis
International Nuclear Information System (INIS)
Andersen, Ken H.; Marero, David Martin y; Barlow, Michael J.
2001-01-01
OSIRIS combines a long-wavelength powder diffractometer with a polarisation analysis backscattering spectrometer. The diffractometer can access wavelengths up to 70 A with a resolution of better than 1% Δd/d. The very high counting-rate at shorter wavelengths is ideal for in-situ, real-time and parametric experiments. The spectroscopy section incorporates an array of graphite crystals arranged in near-backscattering to give a high counting rate with 25 μeV energy resolution. The incident beam is polarised using a supermirror bender and the scattered beam is polarisation-analysed by a 3 He spin-filter in the process of being constructed. The spin-filter system consists of a fibre laser, a peristaltic pump and a wide-angle banana-shaped quartz cell in a continuous-flow setup. The scattered beam passes twice through the spin-filter cell, thus doubling the optical path length in the cell. The aim is to achieve 70% nuclear polarisation with no variation in time. (author)
11. Using acoustic levitation in synchrotron based laser pump hard x-ray probe experiments
Science.gov (United States)
Hu, Bin; Lerch, Jason; Suthar, Kamlesh; Dichiara, Anthony
Acoustic levitation provides a platform to trap and hold a small amount of material by using standing pressure waves without a container. The technique has a potential to be used for laser pump x-ray probe experiments; x-ray scattering and laser distortion from the container can be avoided, sample consumption can be minimized, and unwanted chemistry that may occur at the container interface can be avoided. The method has been used at synchrotron sources for studying protein and pharmaceutical solutions using x-ray diffraction (XRD) and small angle x-ray scattering (SAXS). However, pump-probe experiments require homogeneously excited samples, smaller than the absorption depth of the material that must be held stably at the intersection of both the laser and x-ray beams. We discuss 1) the role of oscillations in acoustic levitation and the optimal acoustic trapping conditions for x-ray/laser experiments, 2) opportunities to automate acoustic levitation for fast sample loading and manipulation, and 3) our experimental results using SAXS to monitor laser induced thermal expansion in gold nanoparticles solution. We also performed Finite Element Analysis to optimize the trapping performance and stability of droplets ranging from 0.4 mm to 2 mm. Our early x-ray/laser demonstrated the potential of the technique for time-resolved X-ray science.
12. Efficient 10 kW diode-pumped Nd:YAG rod laser
Science.gov (United States)
Akiyama, Yasuhiro; Takada, Hiroyuki; Sasaki, Mitsuo; Yuasa, Hiroshi; Nishida, Naoto
2003-03-01
As a tool for high speed and high precision material processing such as cutting and welding, we developed a rod-type all-solid-state laser with an average power of more than 10 kW, an electrical-optical efficiency of more than 20%, and a laser head volume of less than 0.05 m3. We developed a highly efficient diode pumped module, and successfully obtained electrical-optical efficiencies of 22% in CW operation and 26% in QCW operation at multi-kW output powers. We also succeeded to reduce the laser head volume, and obtained the output power of 12 kW with an efficiency of 23%, and laser head volume of 0.045 m3. We transferred the technology to SHIBAURA mechatronics corp., who started to provide the LD pumped Nd:YAG laser system with output power up to 4.5 kW. We are now continuing development for further high power laser equipment.
13. Neutron spin filter based on optically polarized sup 3 He in a near-zero magnetic field
CERN Document Server
Skoy, V R; Sorokin, V N; Kolachevsky, N N; Sobelman, I I; Sermyagin, A V
2003-01-01
A test of polarization of sup 3 He nuclei via spin-exchange collisions with optically pumped rubidium atoms in an extremely low applied magnetic field was carried out. Permalloy magnetic shields were used to prevent a fast relaxation of sup 3 He polarization owing to the inhomogeneity of a surrounding magnetic field. The whole installation was placed at the neutron beam line of the IBR-30 facility, and used as a neutron spin filter. Thus, a prototype of new design of neutron polarizer was introduced. We intend to apply this experience for the full-scale KaTRIn facility to test the time reversal violation in neutron-nuclear reactions.
14. Pump-probe differencing technique for cavity-enhanced, noise-canceling saturation laser spectroscopy.
Science.gov (United States)
de Vine, Glenn; McClelland, David E; Gray, Malcolm B; Close, John D
2005-05-15
We present an experimental technique that permits mechanical-noise-free, cavity-enhanced frequency measurements of an atomic transition and its hyperfine structure. We employ the 532-nm frequency-doubled output from a Nd:YAG laser and an iodine vapor cell. The cell is placed in a folded ring cavity (FRC) with counterpropagating pump and probe beams. The FRC is locked with the Pound-Drever-Hall technique. Mechanical noise is rejected by differencing the pump and probe signals. In addition, this differenced error signal provides a sensitive measure of differential nonlinearity within the FRC.
15. Kinetics of the Electric Discharge Pumped Oxygen-Iodine Laser
Science.gov (United States)
2011-09-01
of the sustainer pulse is tailored to keep the discharge stable. In January 2007, OSU demonstrated a peak laser power of 0.28 W, using a pulser...controlled avalanche ionization, Applied Physics Letters, 22, p. 670, (1973). (57) Hill. A.E., The next generation of controlled avalanche discharge ...pressure oxygen pulsed discharge . Simple and quick method for temperature determination, J. Phys. D:Appl. Phys. 32, pp. 246-250, (1998). (71
16. Low-energy behavior of the 3He(α,γ)7Be cross section
International Nuclear Information System (INIS)
Osborne, J.L.; Barnes, C.A.; Kavanagh, R.W.; Kremer, R.M.; Mathews, G.J.; Zyskind, J.L.; Parker, P.D.; California Inst. of Tech., Pasadena; Howard, A.J.; California Inst. of Tech., Pasadena
1984-01-01
Cross sections for the 3 He(α,γ) 7 Be reaction have been measured at several energies from Esub(c.m.)=165 to 1169 keV by counting prompt γ-rays from a windowless, differentially pumped, recirculating, 3 He gas target. The cross-section factor S 34 (Esub(c.m.)) and branching ratio γ 1 /γ 0 were determined at each energy. Cross sections were also measured at Esub(c.m.)=947 and 1255 keV by counting the γ-rays from the 7 Be produced in a 3 He gas cell with a Ni entrance foil. Combining the results of these two independent experiments yields a zero-energy intercept for the cross-section factor of S 34 (O) = 0.53+-0.03 keV x b. The relationship between these measurements and serveral theoretical calculations, and the import of the extrapolated cross section for the solar-neutrino problem are discussed. (orig.)
17. A 25kW fiber-coupled diode laser for pumping applications
Science.gov (United States)
Malchus, Joerg; Krause, Volker; Koesters, Arnd; Matthews, David G.
2014-03-01
In this paper we report the development of a new fiber-coupled diode laser for pumping applications capable of generating 25 kW with four wavelengths. The delivery fiber has 2.0 mm core diameter and 0.22 NA resulting in a Beam Parameter Product (BPP) of 220 mm mrad. To achieve the specifications mentioned above a novel beam transformation technique has been developed combining two high power laser stacks in one common module. After fast axis collimation and beam reformatting a beam with a BPP of 200 mm mrad x 40 mm mrad in the slow and fast-axis is generated. Based on this architecture a customer-specific pump laser with 25 kW optical output power has been developed, in which two modules are polarization multiplexed for each wavelength (980nm, 1020nm, 1040m and 1060nm). After slow-axis collimation these wavelengths are combined using dense wavelength coupling before focusing onto the fiber endface. This new laser is based on a turn-key platform, allowing straight-forward integration into any pump application. The complete system has a footprint of less than 1.4m² and a height of less than 1.8m. The laser diodes are water cooled, achieve a wall-plug efficiency of up to 60%, and have a proven lifetime of <30,000 hours. The new beam transformation techniques open up prospects for the development of pump sources with more than 100kW of optical output power.
18. GaAs-based high temperature electrically pumped polariton laser
Energy Technology Data Exchange (ETDEWEB)
Baten, Md Zunaid; Bhattacharya, Pallab, E-mail: [email protected]; Frost, Thomas; Deshpande, Saniya; Das, Ayan [Center for Photonic and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lubyshev, Dimitri; Fastenau, Joel M.; Liu, Amy W. K. [IQE, Inc., 119 Technology Drive, Bethlehem, Pennsylvania 18015 (United States)
2014-06-09
Strong coupling effects and polariton lasing are observed at 155 K with an edge-emitting GaAs-based microcavity diode with a single Al{sub 0.31}Ga{sub 0.69}As/Al{sub 0.41}Ga{sub 0.59}As quantum well as the emitter. The threshold for polariton lasing is observed at 90 A/cm{sup 2}, accompanied by a reduction of the emission linewidth to 0.85 meV and a blueshift of the emission wavelength by 0.89 meV. Polariton lasing is confirmed by the observation of a polariton population redistribution in momentum space and spatial coherence. Conventional photon lasing is recorded in the same device at higher pump powers.
19. Compact, diode-pumped, solid-state lasers for next generation defence and security sensors
Science.gov (United States)
Silver, M.; Lee, S. T.; Borthwick, A.; McRae, I.; Jackson, D.; Alexander, W.
2015-06-01
Low-cost semiconductor laser diode pump sources have made a dramatic impact in sectors such as advanced manufacturing. They are now disrupting other sectors, such as defence and security (D&S), where Thales UK is a manufacturer of sensor systems for application on land, sea, air and man portable. In this talk, we will first give an overview of the market trends and challenges in the D&S sector. Then we will illustrate how low cost pump diodes are enabling new directions in D&S sensors, by describing two diode pumped, solid- state laser products currently under development at Thales UK. The first is a new generation of Laser Target Designators (LTD) that are used to identify targets for the secure guiding of munitions. Current systems are bulky, expensive and require large battery packs to operate. The advent of low cost diode technology, merged with our novel solid-state laser design, has created a designator that will be the smallest, lowest cost, STANAG compatible laser designator on the market. The LTD delivers greater that 50mJ per pulse up to 20Hz, and has compact dimensions of 125×70×55mm. Secondly, we describe an ultra-compact, eye-safe, solid-state laser rangefinder (LRF) with reduced size, weight and power consumption compared to existing products. The LRF measures 100×55×34mm, weighs 200g, and can range to greater than 10km with a single laser shot and at a reprate of 1Hz. This also leverages off advances in laser pump diodes, but also utilises low cost, high reliability, packaging technology commonly found in the telecoms sector. As is common in the D&S sector, the products are designed to work in extreme environments, such as wide temperature range (-40 to +71°C) and high levels of shock and vibration. These disruptive products enable next- generation laser sensors such as rangefinders, target designators and active illuminated imagers.
20. XeF pump laser. Final technical report
International Nuclear Information System (INIS)
1980-03-01
The goal of this program was to demonstrate operation of an XeF laser of adequate energy, efficiency and beam quality at high repetition rates. The specific design goals were: PRF greater than or equal to 10 kHz, energy output greater than or equal to 50 mJ/pulse, efficiency greater than or equal to 0.3%, and beam divergence angle less than or equal to 20x diffraction limited. In the following sections of this report we will discuss how these goals have been met
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https://lqp2.org/welcome?page=2
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# Welcome to LQP2
This is the successor of the Local Quantum Physics Crossroads (LQP 1.0) website. Its purpose is to gather as much LQP-related information as possible in one place. Feel free to add papers to the article database and books to the bibliography. You are also encouraged to post information about upcoming events and job opportunities.
In case you spot a bug, have suggestions for improvements or want to help with development, please let the administrators know via the contact form (login required).
• ## Non-trivial bundles and Algebraic Classical Field Theory
October 27, 2022
• ## The quantization of Proca fields on globally hyperbolic spacetimes: Hadamard states and Møller operators
October 17, 2022
• ## Strict deformation quantization and local spin interactions
October 19, 2022
• ## Unitary, anomalous Master Ward Identity and its connections to the Wess-Zumino condition, BV formalism and $L_\infty$-algebras
October 12, 2022
• ## Spring School Interactions between Poisson Geometry and Quantisation
March 20, 2023 - March 24, 2023
• ## Local and Covariant Flow Relations for OPE Coefficients in Lorentzian Spacetimes
September 18, 2022
• ## Emergent phenomena in Nature: a paradox with Theory?
September 21, 2022
• ## How the Higgs potential got its shape
September 13, 2022
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https://www.physicsforums.com/threads/dimensions-of-intensity.733286/
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# Dimensions of intensity
1. Jan 17, 2014
### Old Guy
1. The problem statement, all variables and given/known data
I know that intensity is power per unit area. When I do a dimensional analysis, it reduces down to mass per cubic time. Is there any physical significance to that?
2. Relevant equations
I=P/A
3. The attempt at a solution
2. Jan 17, 2014
### lightgrav
Not really, because that form has removed all the geometry of the situation;
Intensity's geometry comes from the energy flow vector piercing an Area, so a flow Volume is indicated.
On the other hand, if you divide the intensity by flow velocity, you end with m v^2 / length^3 ;
light's intensity divided by light speed leaves you with mc^2 / volume, the energy density in the light.
Draft saved Draft deleted
Similar Discussions: Dimensions of intensity
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https://lavelle.chem.ucla.edu/forum/viewtopic.php?p=207805
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## ICE
Erik Buetow 1F
Posts: 96
Joined: Fri Aug 30, 2019 12:15 am
### ICE
When should we use the ice table vs when do we just use the normal equilibrium concentration? Is the ICE table only used when a reaction is not in equilibrium and we need to find information from it?
Jessica Booth 2F
Posts: 101
Joined: Fri Aug 30, 2019 12:18 am
### Re: ICE
The ice tables are mainly used when we only know the initial concentration(s) and the equilibrium constant. Basically, we use ice tables when we are unable to just use the equilibrium concentrations and equilibrium constant to find the other equilibrium concentrations.
jisulee1C
Posts: 149
Joined: Thu Jul 25, 2019 12:17 am
### Re: ICE
ICE charts can be used to find equilibrium molar concentration using molar ratios and the change in molar concentration if the initial molar concentration for either reactants or products are given and the equilibrium constant is also given.
DLee_1L
Posts: 103
Joined: Sat Aug 17, 2019 12:17 am
### Re: ICE
Also, ICE tables are used to find the equilibrium concentrations for weak acids and bases that don't fully dissociate.
805373590
Posts: 101
Joined: Wed Sep 11, 2019 12:17 am
### Re: ICE
ICE tables are used when the problem is only providing the initial concentrations and we are trying to find the ph or ooh of weak acids or bases
Tahlia Mullins
Posts: 105
Joined: Thu Jul 25, 2019 12:15 am
### Re: ICE
To determine if an ICE table is necessary, look at the information given. Such as, if the initial concentration(s) are given along with a Ka or Kb value, then an ICE table is the correct method in finding the equilibrium concentrations and other information.
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https://www.amtoolbox.org/amt-1.1.0/doc/data/data_ziegelwanger2014.php
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# THE AUDITORY MODELING TOOLBOX
Applies to version: 1.1.0
Go to function
# DATA_ZIEGELWANGER2014 - Data from Ziegelwanger and Majdak (2014)
## Usage
data = data_ziegelwanger2014(flag)
## Description
data_ziegelwanger2014(flag) returns results for different HRTF databases from Ziegelwanger and Majdak (2014).
The flag may be one of:
'ARI' ARI database. The output has the following fields: data.results and data.subjects. 'CIPIC' CIPIC database. The output has the following fields: data.results and data.subjects. 'LISTEN' LISTEN database. The output has the following fields. data.results and data.subjects. 'SPHERE_ROT' HRTF sets for a rigid sphere placed in the center of the measurement setup and varying rotation. The output has the following fields: data.results, data.subjects, data.phi, data.theta and data.radius. 'SPHERE_DIS' HRTF sets for a rigid sphere with various positions in the measurement setup. The output has the following fields: data.results, data.subjects, data.xM, data.yM, data.zM and data.radius. 'Sphere' HRTF set for a rigid sphere: The output has the following fields: data.hM, data.meta and data.stimPar. 'SAT' HRTF set for a rigid sphere combined with a neck and a torso: The output has the following fields: data.hM, data.meta and data.stimPar. 'STP' HRTF set for a rigid sphere combined with a neck, a torso and a pinna: The output has the following fields: data.hM,data.meta and data.stimPar. 'NH89' HRTF set of listener NH89 of the ARI database: The output has the following fields: data.hM, data.meta and data.stimPar.
The fields are given by:
data.results Results for all HRTF sets
data.subjects IDs for HRTF sets
data.phi Azimuth of ear position
data.theta Elevation of ear position
data.xM x-coordinate of sphere center
data.yM y-coordinate of sphere center
data.zM z-coordinate of sphere center
data SOFA object
## Requirements:
1. SOFA API from http://sourceforge.net/projects/sofacoustics for Matlab (in e.g. thirdparty/SOFA)
2. Optimization Toolbox for Matlab
3. Data in hrtf/ziegelwanger2014
## Examples:
To get results from the ARI database, use:
data=data_ziegelwanger2014('ARI');
## References:
H. Ziegelwanger and P. Majdak. Modeling the direction-continuous time-of-arrival in head-related transfer functions. J. Acoust. Soc. Am., 135:1278--1293, 2014.
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http://crypto.stackexchange.com/tags/hmac
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# Tagged Questions
HMAC is a method for constructing a message authentication code based on a cryptographic hash function.
776 views
### Is there a null HMAC?
I came up with this question while unit testing a function that includes an HMAC. What is the expected behavior of an HMAC with a well-defined key and a set of data with no elements in it? Is there ...
23 views
### Deriving a key for HMAC, using PBKDF2
What is the recommended way to derive a key for an HMAC-SHA256, from a passphrase and salt? I'd like to compute an HMAC-SHA256. I have a passphrase, and a message. I note that RFC-7518 (JWA) ...
38 views
### NIST HMAC Test vectors
I am searching test vectors of the HMAC-SHA256 primitive to verify the correctness of an implementation. Without hesitation I go on the NIST website to see what they offer. While reading the ...
18 views
### Is there any code implementation of the HMAC-DRBG PRNG? [closed]
I'm looking for the code of HMAC-DRBG in either C# or C++, for use in a cryptography related project. I can't find it anywhere. Would appreciate the help! Thanks a ton!
86 views
### Side channel security of HMAC in software
Assume we have a processor with a symmetric co-processor that supports AES. This processor does however not provide co-processor support for hash algorithms such as SHA-1 or SHA-256. I've got the ...
59 views
For a personal project, I'm building a password manager, based off the project in this syllabus from Stanford http://crypto.stanford.edu/~dabo/cs255/hw_and_proj/proj1.pdf Since I don't exactly have ...
89 views
### Difference between AES CMAC and AES HMAC?
Can someone elaborate on how 'signing' is done using AES- CMAC and AES-HMAC? HMAC Signing as I understand: Compute the HMAC( Hash the key and the input concatenated in a special way) Verification: ...
909 views
### Could an HMAC be used as a hash?
MD5 is considered broken and SHA-1 is closely following, but HMACs built around either are still considered relatively secure. It makes me wonder if MD5 and SHA-1 HMACs can be used as secure hashes. ...
47 views
### Is the security of an HMAC equally important as the security of the cipher itself?
I'm a little unclear on how hash based MAC works... So I would like to know, is the security of your hash function as important as the security of the overall cipher? Basically, if you can crack the ...
39 views
### Keys and key-stretching when authenticating requests?
I'm making a REST application and still a bit confused about this issue. basically, to authenticate incoming requests, I give out userId, issued timestamp, expiry timestamp (normally 3 months after ...
38 views
### Why does NaCl's crypto_auth have twice the security level of crypto_onetimeauth?
The crypto_auth function produces a 256-bit HMAC, with a 512-bit version also available. But the crypto_onetimeauth function ...
68 views
### Would it be better to use HKDF or SCrypt for deriving a child key?
Okay so I'm trying to derive a child public key from an EC public key. I've come up with a couple ideas and now I'd like to know which is more secure. Mp: The master key pair, this includes a ...
136 views
### What size should the HMAC key be with SHA-256?
I'm trying to generate a secret key to be used for HMAC SHA-256 signature processing. I've seen many sample of keys with variable length from 32 characters to 96 characters. What is the ironclad rule ...
36 views
### PBEWithMD5AndDES Cipher does not check for integrity first?
I am running FindBugs with findsecbugs plugin to scan java code for security issues. I am getting "Cipher With No Integrity" error for a Cipher function implemented with "PBEWithMD5AndDES". The legend ...
55 views
### Compromise between HMAC and Digital Signature, by encrypting and sending secret key?
For achieving stateless authentication tokens (like JWT), is there a compromise between the performance of HMAC, and public key distribution of Digital Signature? Scenario: Sender is a centralized ...
74 views
### Is it okay to use an HMAC of the plaintext and a (possibly distinct) key as the IV for symmetric cryptography?
I was thinking of how to create an IV for a block cipher that doesn't require stored state, and I came up with the idea of using an HMAC of the (padded) plaintext and a (possibly distinct) key as the ...
29 views
### Execution time for HMAC-MD5 on a 160 bit data using 128 bit key on a 3GHz CPU [closed]
I need to know the execution time for HMAC -MD5 for a 160 bit data using 128 bit key on a 3 Ghz CPU, kindly specify other parameters of the machine like RAM, operating system used etc
18 views
### Comparison of Execution time for HMAC MD5 and a multliplication and pairing operations in G, on same CPU [closed]
I am a beginner in cryptography,One of the module in my project is to make a comparison, between the execution time taken by an HMAC- MD5 operation on 160 bit data, using a 128 bit key and sum of ...
76 views
### Using HMAC as a nonce with AES-CTR encrypt-and-MAC
Suppose I use the following encrypt-and-MAC construction: $E(k_1, k_2, n, m) = E_\text{AES256-CTR}(k_1, n, m) \| \text{HMAC-SHA256}(k_2, m)$, where: $k_1$ and $k_2$ are 256-bit keys $n$ ...
31 views
### Should I authenticate memory data which was loaded from authenticated disk file?
Encrypted fields are loaded from disk file to process memory only after file's HMAC validation is successful. Data is still encrypted in memory and will be decrypted later, on demand, when it needs to ...
236 views
### HMAC vs ECDSA for JWT
I will be implementing JSON web tokens into my website and have a question about implementing them. I have a choice of using two algorithms, HMAC-SHA256 and ECDSA-SHA256. I have used HMAC-SHA256 in ...
94 views
### Is it an overkill to add external integrity check to the AES-GCM encoding?
There is a java library for android which implements integrity checking to predefined encrypting mode(which can be found here). Short class description from author page to avoid further questions ...
52 views
### If a PRG is constructed by iterating a PRF, is it backtracking-resistant?
Say we construct a pseudo-random number generator from a pseudo-random function $f$ (using some constant key $k$ and some initial value $v_0$). We do this by feeding the output block of the PRF back ...
44 views
### Is it possible to have self-authenticated message?
Consider a text with $n$ words which $m$ words of it can be replaced with an equivalent word. Therefore we have $2^m$ different texts with the same meaning. For example "You are {so/very} ...
60 views
### Is a nonce considered 'secret' enough for HMAC?
We're implementing a mobile application which communicates with a web service, and on first install the user sends its deviceid to the web service (over TLS, unauthenticated at this point) - which ...
69 views
### Why does HKDF use HMAC(salt, key) instead of HMAC(key, salt)?
I've been looking over the HKDF specs (RFC 5869), and something I noticed is that in the key and salt are reversed: ...
400 views
### Why do cryptographic hashes need to be fixed length?
Why do cryptographic hashes need to have a fixed length output? I know that the shallow answer is that an output that varies by key size or file size can leak information somehow, leading to ...
62 views
### Is it wise to use HOTP (raw bytes) as a key for HMAC?
Assume I have client and server applications with a shared master secret KEY_SECRET already in place. Also assume that the client and server have an implicit shared ...
62 views
### How to key an HMAC with keys from separate mutually untrusted parties?
The problem is as follows: There are two parties, both of whom would like to HMAC a message with a key. Although the keys are known to one another, both parties do not trust that the other one ...
100 views
### Double randomised HMAC verification to prevent timing attack
A way to prevent timing attacks for hash string comparison is to perform additional HMAC signing in order to randomize the verification process (see Double HMAC Verification). In addition to the ...
123 views
### HMAC-SHA256 on large data files
I currently need to encrypt large files (video, over 6 Gbytes) for our customers. To ensure authenticity and integrity, we chose HMAC-256 as we already use it in our internal messaging system. But ...
173 views
### Encrypt large data with RSA through blocks in java
I'm working on a communication protocol where a client sends encrypted data to a server. What happens is that in some point, the client creates a symmetric key used to create data digests through the ...
112 views
### HMAC key storage for a web app?
If one is going to use an HMAC, I.E: http://php.net/manual/en/function.hash-hmac.php, where exactly are they storing the key? Without some sort of secure storage (i.e not in a local file or code), I ...
32 views
### For the scrypt HMAC storage format, why run the input of the hash and the hash itself into the HMAC
Generally if the body is hashed, why provide the body and the hash as input into the HMAC. Instead wouldn't the same security be achieved by hashing the body and providing only the hash as input into ...
40 views
### Is it secure to use TOTP with same key and different time-counters?
If I use TOTP to generate codes with different "expiration" time, using the same key for HMAC, will I create some kind of weakness?
67 views
### Is it safe to use single-block AES for mutual authentication?
I read the question Symmetric mutual authentication with client using a derived secret and its answer which, if I'm not mistaken, assert that it should be safe to use the proposed protocol for mutual ...
69 views
### Is this scheme to derive multiple keys secure?
I need a cryptographic scheme to generate a deterministic chain of private keys that look random to outside observer but can always be reconstructed from a single root key, also: Neither private ...
42 views
### Digital signatures using a partially public key
I'm thinking to sign a message using a key that is made up of a publicly shared key and a privately shared key. The operation for mixing the two keys could be concatenation, if it suffices. To ...
58 views
### Avoiding replay attack on certified announcements
Suppose two agents A and B share a common secret and A makes a regular unique 16-byte ...
66 views
### Is this a proper PBKDF2 key derivation function algorithm?
I've started implementing PBKDF2 algorithm recently and since I'm new in crypto, I would like to ask if my implementation is good. I looked up some documentations and I tried to follow many of them ...
101 views
### Two rounds of SHA-256 HMAC?
In a project we are working on, we have two applications within our datacenter that exchange messages. The messages are protected by an HMAC, and the secret key is stored on a SafeNet device. Update ...
86 views
### A periodic PRNG based on hash function?
I need a PRNG which provides 128 bytes numbers. Let's say that given a symmetric key $K$ and an internal state $s$ I use the PRF HMAC-SHA512 this way: The output is PRNG($K, s$) = ...
77 views
### Is a 256 bit HMAC-SHA256 key compromised if the tail is used for identification?
Using a truncated hash of a key seems to be a safe way to identify the key (i.e. key fingerprint), but what about truncating a key itself in the case of HMAC-SHA256? Example: ...
341 views
### Is calculating HMAC from hashed input a good idea?
Original HMAC algorithm is as follows: H(K XOR opad || H(K XOR ipad || text)) What if text would replaced with H(text)? ...
131 views
### How does the HOTP dynamic truncation function generalize to longer hashes?
HOTP, the HMAC-based One-Time Password algorithm from RFC 4226, uses a "dynamic truncation" function to turn the 20 byte HMAC-SHA-1 value into a 31 bit string. The dynamic truncation (from Section ...
338 views
### What are the implications of a birthday attack on a HMAC?
After collecting approximately $2^{n/2}$ message-tag pairs a collision can be observed. So two different messages (m1 and m2) will have the same tag. This paper states: Then, for any string x, ...
80 views
### Chance to find HMAC key/salt when having knowledge of the hashed data?
I'm not sure how to word this... I'm working with a HMAC (I think of it being a "salted hash"). I know the entire string being hashed, I do NOT know the salt. I also know the first 8 characters of the ...
104 views
### Keys in HMAC and NMAC
I'm quite new to this topic and have several questions concerning HMAC and NMAC: Why does NMAC need two keys? How can it be attacked if we just used some sort of initialization vector instead of the ...
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http://www.ams.org/joursearch/servlet/PubSearch?f1=msc&pubname=all&v1=34B15&startRec=91
|
# American Mathematical Society
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AMS eContent Search Results
Matches for: msc=(34B15) AND publication=(all) Sort order: Date Format: Standard display
Results: 91 to 120 of 147 found Go to page: 1 2 3 4 5
[91] L. H. Erbe and Haiyan Wang. On the existence of positive solutions of ordinary differential equations . Proc. Amer. Math. Soc. 120 (1994) 743-748. MR 1204373. Abstract, references, and article information View Article: PDF This article is available free of charge [92] Dariusz Bielawski. Generic properties of the Nicoletti and Floquet boundary value problems . Proc. Amer. Math. Soc. 120 (1994) 831-841. MR 1195712. Abstract, references, and article information View Article: PDF This article is available free of charge [93] Alessandro Fonda. On the existence of periodic solutions for scalar second order differential equations when only the asymptotic behaviour of the potential is known . Proc. Amer. Math. Soc. 119 (1993) 439-445. MR 1154246. Abstract, references, and article information View Article: PDF This article is available free of charge [94] Pierpaolo Omari and Fabio Zanolin. Nonresonance conditions on the potential for a second-order periodic boundary value problem . Proc. Amer. Math. Soc. 117 (1993) 125-135. MR 1143021. Abstract, references, and article information View Article: PDF This article is available free of charge [95] Nicholas D. Alikakos, Peter W. Bates and Giorgio Fusco. Solutions to the nonautonomous bistable equation with specified Morse index. I. Existence . Trans. Amer. Math. Soc. 340 (1993) 641-654. MR 1167183. Abstract, references, and article information View Article: PDF This article is available free of charge [96] Kevin McLeod. Uniqueness of positive radial solutions of $\Delta u+f(u)=0$ in ${\bf R}\sp n$. II . Trans. Amer. Math. Soc. 339 (1993) 495-505. MR 1201323. Abstract, references, and article information View Article: PDF This article is available free of charge [97] Man Kam Kwong and Yi Li. Uniqueness of radial solutions of semilinear elliptic equations . Trans. Amer. Math. Soc. 333 (1992) 339-363. MR 1088021. Abstract, references, and article information View Article: PDF This article is available free of charge [98] Alexander Nabutovsky. Number of solutions with a norm bounded by a given constant of a semilinear elliptic PDE with a generic right-hand side . Trans. Amer. Math. Soc. 332 (1992) 135-166. MR 1066447. Abstract, references, and article information View Article: PDF This article is available free of charge [99] Anna Capietto, Jean Mawhin and Fabio Zanolin. Continuation theorems for periodic perturbations of autonomous systems . Trans. Amer. Math. Soc. 329 (1992) 41-72. MR 1042285. Abstract, references, and article information View Article: PDF This article is available free of charge [100] Jie Jiang and Xue Kong Wang. A singular perturbation nonlinear boundary value problem and the $E$-condition for a scalar conservation law. Quart. Appl. Math. 50 (1992) 547-557. MR MR1178434. Abstract, references, and article information View Article: PDF This article is available free of charge [101] A. Fonda and A. C. Lazer. Subharmonic solutions of conservative systems with nonconvex potentials . Proc. Amer. Math. Soc. 115 (1992) 183-190. MR 1087462. Abstract, references, and article information View Article: PDF This article is available free of charge [102] Donal O’Regan. Boundary value problems for second and higher order differential equations . Proc. Amer. Math. Soc. 113 (1991) 761-775. MR 1069295. Abstract, references, and article information View Article: PDF This article is available free of charge [103] Manuel A. del Pino and Raúl F. Manásevich. Multiple solutions for the $p$-Laplacian under global nonresonance . Proc. Amer. Math. Soc. 112 (1991) 131-138. MR 1045589. Abstract, references, and article information View Article: PDF This article is available free of charge [104] Manuel A. del Pino and Raúl F. Manásevich. Existence for a fourth-order boundary value problem under a two-parameter nonresonance condition . Proc. Amer. Math. Soc. 112 (1991) 81-86. MR 1043407. Abstract, references, and article information View Article: PDF This article is available free of charge [105] R. Kannan and Kent Nagle. Forced oscillations with rapidly vanishing nonlinearities . Proc. Amer. Math. Soc. 111 (1991) 385-393. MR 1028287. Abstract, references, and article information View Article: PDF This article is available free of charge [106] M. N. Nkashama. Periodically perturbed nonconservative systems of Li\'enard type . Proc. Amer. Math. Soc. 111 (1991) 677-682. MR 1057959. Abstract, references, and article information View Article: PDF This article is available free of charge [107] Lorenzo Sadun and Jan Segert. Non-self-dual Yang-Mills connections with nonzero Chern number. Bull. Amer. Math. Soc. 24 (1991) 163-170. MR 1067574. Abstract, references, and article information View Article: PDF [108] Greg A. Harris. The influence of boundary data on the number of solutions of boundary value problems with jumping nonlinearities . Trans. Amer. Math. Soc. 321 (1990) 417-464. MR 961622. Abstract, references, and article information View Article: PDF This article is available free of charge [109] Anthony G. O’Farrell and Donal O’Regan. Existence results for some initial and boundary value problems . Proc. Amer. Math. Soc. 110 (1990) 661-673. MR 1021212. Abstract, references, and article information View Article: PDF This article is available free of charge [110] R. Iannacci and M. N. Nkashama. Nonlinear two-point boundary value problems at resonance without Landesman-Lazer condition . Proc. Amer. Math. Soc. 106 (1989) 943-952. MR 1004633. Abstract, references, and article information View Article: PDF This article is available free of charge [111] Jairo Santanilla. Existence of nonnegative solutions of a semilinear equation at resonance with linear growth . Proc. Amer. Math. Soc. 105 (1989) 963-971. MR 964462. Abstract, references, and article information View Article: PDF This article is available free of charge [112] C. Y. Chan and Y. C. Hon. Computational methods for generalized Thomas-Fermi models of neutral atoms. Quart. Appl. Math. 46 (1988) 711-726. MR 973385. Abstract, references, and article information View Article: PDF This article is available free of charge [113] Ning Mao Xia. The density function of the solution of a two-point boundary value problem containing small stochastic processes. Quart. Appl. Math. 46 (1988) 29-47. MR 934679. Abstract, references, and article information View Article: PDF This article is available free of charge [114] Yi Song Yang. Fourth-order two-point boundary value problems . Proc. Amer. Math. Soc. 104 (1988) 175-180. MR 958062. Abstract, references, and article information View Article: PDF This article is available free of charge [115] C. Y. Chan and Y. C. Hon. A constructive solution for a generalized Thomas-Fermi theory of ionized atoms. Quart. Appl. Math. 45 (1987) 591-599. MR 910465. Abstract, references, and article information View Article: PDF This article is available free of charge [116] L. E. Bobisud and D. O’Regan. Boundary value problems for first-order differential equations . Proc. Amer. Math. Soc. 99 (1987) 501-506. MR 875388. Abstract, references, and article information View Article: PDF This article is available free of charge [117] M. Arias. Existence results on the one-dimensional Dirichlet problem suggested by the piecewise linear case . Proc. Amer. Math. Soc. 97 (1986) 121-127. MR 831399. Abstract, references, and article information View Article: PDF This article is available free of charge [118] R. Kannan and R. Ortega. Existence of solutions of $x''+x+g(x)=p(t),\;x(0)=0=x(\pi)$ . Proc. Amer. Math. Soc. 96 (1986) 67-70. MR 813812. Abstract, references, and article information View Article: PDF This article is available free of charge [119] Christian Schmeiser. Approximate solution of boundary value problems on infinite intervals by collocation methods . Math. Comp. 46 (1986) 479-490. MR 829620. Abstract, references, and article information View Article: PDF This article is available free of charge [120] J. Mawhin, J. R. Ward and M. Willem. Necessary and sufficient conditions for the solvability of a nonlinear two-point boundary value problem . Proc. Amer. Math. Soc. 93 (1985) 667-674. MR 776200. Abstract, references, and article information View Article: PDF This article is available free of charge
Results: 91 to 120 of 147 found Go to page: 1 2 3 4 5
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http://mathhelpforum.com/algebra/21522-summing-question.html
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1. ## Summing - question
Hey guys, just a quick query. The question says:
Find, as polynomials in n, the sum of
1.2.3 + 2.3.4 + ..... + n(n+1)(n+2)
__________________________________________________ _____
Is that simply
$\Sigma_{k=1}^{n} k(k+1)(k+2) = \Sigma_{k=1}^{n} k^3 + 3 \Sigma_{k=1}^{n} k^2 + 2 \Sigma_{k=1}^{n} k$
which, skipping through the steps is:
$\frac{1}{4}n(n+1)(n+2)(n+3)$
This is what they're asking for, aren't they?
2. Originally Posted by WWTL@WHL
Hey guys, just a quick query. The question says:
Find, as polynomials in n, the sum of
1.2.3 + 2.3.4 + ..... + n(n+1)(n+2)
__________________________________________________ _____
Is that simply
$\Sigma_{k=1}^{n} k(k+1)(k+2) = \Sigma_{k=1}^{n} k^3 + 3 \Sigma_{k=1}^{n} k^2 + 2 \Sigma_{k=1}^{n} k$
which, skipping through the steps is:
$\frac{1}{4}n(n+1)(n+2)(n+3)$
This is what they're asking for, aren't they?
yes, provided you made no mistakes in your "skipping through the steps" section, that is what they're after. you could probably expand it though, so it is in somewhat more of a standard form
3. Yes, that is exactly what they want.
4. Fantastic. Just making sure, since this is worded a lot differently from when I encountered similar questions at school.
Thanks guys.
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http://dev.goldbook.iupac.org/terms/view/M03688
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magnetic moment $$m$$, $$\mu$$
https://doi.org/10.1351/goldbook.M03688
Vector quantity, the vector product of which with the @M03686@ of a homogeneous field is equal to the @T06400@.
Source:
Green Book, 2nd ed., p. 21 [Terms] [Book]
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https://chapel-lang.org/docs/latest/tools/chpldoc/chpldoc.html
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# chpldoc¶
chpldoc is a tool for generating HTML based documentation from Chapel source code and embedded comments. It is similar in spirit to Godoc, Javadoc, and Pydoc. chpldoc is used to produce Chapel's web documentation for the Standard Library and Built-in-Types and Functions.
See the online man page for all available flags.
## Building chpldoc¶
To build chpldoc, use:
[g]make chpldoc
This downloads the required Python package dependencies and creates the chpldoc program in the same directory as the chpl compiler.
To ensure chpldoc is installed properly, optionally run the automatic sanity check:
[g]make check-chpldoc
chpldoc depends on several Python packages. The full list is available in $CHPL_HOME/third-party/chpl-venv/README.md including details on each package. ## Documenting Chapel code¶ To document Chapel code, place a multi-line comment just prior to the definition of the symbol --- module, class, function, method, global variable, etc. --- that you wish to comment. All multi-line comments are considered potential documentation. Documentation is output in the same order that it exists in the source. Documentation text within comments is parsed as ReStructured Text. ## Documenting Modules¶ To document individual modules, inside the Chapel standard library or elsewhere, use the chpldoc command directory. For example: chpldoc modules/standard/Random.chpl By default, documentation created by chpldoc will end up in a subdirectory of the current working directory named 'docs/'. You can specify a different directory name using the --docs-dir option. As an example, there is a primer on the chpldoc capability in $CHPL_HOME/examples/primers/ that can be turned into documentation using:
cd $CHPL_HOME/examples/primers chpldoc chpldoc.chpl The output documentation will be located in: $CHPL_HOME/examples/primers/docs/chpldoc.html
### Comment style¶
For the Chapel standard modules, it is recommended to use multiline comments without any per-line prefixes. This results in the most consistent, best looking output. For example:
/* Support for buffers - ...
Provides bytes and buffer types, which can be used to...
*/
module Buffers {
...
### Argument and return/yield types¶
Arguments and their types can optionally be documented using the :arg: and :type: fields. For the Chapel standard modules, :arg: should be a concise description of the argument using a sentence, or two. This should include any constraints and default information. :type: should be the literal type for the parameter. A link will be created to the type, if possible. For example:
/* Fill and array with pseudorandom values ...
:arg arr: Array to be filled, where T is real(64), imag(64), or complex(128).
:type arr: [] T
:arg seed: Integer seed to use for the PRNG. Defaults to :proc:SeedGenerator.currentTime.
:type seed: int(64)
*/
proc fillRandom(arr: [], seed: int(64) = SeedGenerator.currentTime) {
...
Return or yield types can optionally be documented using the :returns: and :yields: fields, and the :rtype: and :ytype: fields. :returns: and :rtype: are for procedures and methods, while :yields: and :ytype: are for iterators.
Similar to arguments, the :returns: and :yields: should be a concise description of the return value or yield value, including any constraints, using a sentence, or two. :rtype: and :ytype: should be the literal types. A link to the type will be created, if possible. For example:
/* Returns the next value in the random stream.
:returns: Next value in the random integer stream.
:rtype: int
*/
proc RandomStream.getNext(): int {
...
/* Simple find-like utility for iterating over files.
:arg startdir: Directory to start looking for files.
:arg recursive: Whether or not to descend recursively into directories.
:arg hidden: Whether or not to yield hidden files.
:yields: Filenames found in startdir based on input arguments.
:ytype: string
*/
iter findfiles(startdir=".", recursive=false, hidden=false): string {
...
Note
• Leave an empty line above and below all these fields for best results.
• All of these fields must be left-aligned with the outer most paragraph(s).
For more information see the Documenting argument, return, and yield values and types section.
### Stifling documentation¶
To mark a particular symbol to not be output as part of the documentation, preface the symbol with the pragma "no doc". For example:
pragma "no doc"
proc foo() { ... }
Private symbols are not documented by default.
private proc foo() { ... }
Note
Private cannot be applied to all symbols at this time. It is currently limited to functions, iterators, globals, and modules. Not supported are type aliases, enum declarations, classes/records/unions, methods, and fields.
## reStructuredText primer¶
This section is a brief introduction to reStructuredText (aka reST). It is intended to provide Chapel developers with enough information to write documentation in comments in the source code.
The Python and Sphinx projects have thorough primers of reST. Please see those for more detail.
This primer is based on the information and text in the Sphinx and Python reST primers (some of the text is copied verbatim).
The authoritative reStructuredText User Guide is also helpful.
### Paragraphs¶
Simple chunks of text. Paragraphs can have line breaks to improve source readability. Separate paragraphs with an empty line. Indentation is significant in reST. All lines of paragraph must be left-aligned.
### Inline markup¶
• one asterisk: *text* for emphasis (italics),
• two asterisks: **text** for strong emphasis (boldface), and
• backquotes: text for code samples.
If asterisks or backquotes appear in running text and could be confused with inline markup delimiters, they have to be escaped with a backslash.
### Lists and Quotes¶
To create a list, put an asterisk at the start of a paragraph and indent accordingly. Create numbered lists by using the literal numbers, e.g. 1., 2.. Automatically numbered lists begin with #.:
* This is a bulleted list.
* It has two items, the second
item uses two lines.
1. This is a numbered list.
2. It has two items too.
#. This is a numbered list.
#. It has two items too.
Nested lists are possible, but be aware that they must be separated from the parent list items by blank lines:
* a
* b
* nested
* blah
* my final item, in the parent list
### Source Code¶
Literal code blocks are introduced by ending a paragraph with the special marker ::. The literal block must be indented:
This is a normal text paragraph. The next paragraph is a code sample::
It is not processed in any way, except
that the indentation is removed.
It can span multiple lines.
This is a normal text paragraph again.
The handling of the :: marker is smart:
• If it occurs as a paragraph of its own, that paragraph is completely left out of the document.
• If it is preceded by whitespace, the marker is removed.
• If it is preceded by non-whitespace, the marker is replaced by a single colon.
That way, the second sentence in the above example's first paragraph would be rendered as "The next paragraph is a code sample:".
The highlight language is configured with the highlight directive. The configured language is used for all literal blocks until the next highlight directive. For example:
.. highlight:: chapel
Chapel code::
writeln("Hello from Chapel!");
More chapel::
x <=> y;
.. highlight:: c
::
printf("Hello from C!\n");
### Showing code examples¶
The code-block directive can be used to specify the highlight language of a single code block. For example:
.. code-block:: chapel
use Foo;
proc bar() {
writeln("Fooy!");
}
If highlighting with the specified language fails, e.g. if the syntax is not parsable, the block is not highlighted in anyway. Note that there should be a blank line between the code-block directive and the indented code snippet.
### Sections¶
Section headers are created by underlining (and optionally overlining) the section title with a punctuation character, at least as long as the text:
This is a heading
=================
There are no heading levels assigned to certain characters. The structure is determined from the succession of headings.
Every explicit markup block which is not a valid markup construct is regarded as a comment. For example:
This is a normal paragraph.
It is interesting.
.. TODO: Make it more interesting.
Another paragraph goes here.
You can indent text after a comment start to form multiline comments:
..
This whole indented block
is a comment.
Still in the comment.
### Inline markup¶
As said before, Sphinx uses interpreted text roles to insert semantic markup in documents.
Names of builtins, like true, false, types like int(64), and local variables, such as function/method arguments, are an exception, they should be marked simply with myVar.
For all other roles, you have to write :rolename:content.
There are some additional facilities that make cross-referencing roles more versatile:
• You may supply an explicit title and reference target, like in reST direct hyperlinks: :role:title <target> will refer to target, but the link text will be title.
• If you prefix the content with !, no reference/hyperlink will be created.
• For the Chapel roles, if you prefix the content with ~, the link text will only be the last component of the target. For example, :proc:~Random.RandomStream.fillRandom will refer to Random.RandomStream.fillRandom but only display fillRandom as the link text.
In HTML output, the link's title attribute (that is e.g. shown as a tool-tip on mouse-hover) will always be the full target name.
The following roles refer to objects in modules and are possibly hyperlinked if a matching identifier is found:
:mod:
Reference a module; a dotted name may be used. See cross-references for details on dotted and non-dotted names.
:proc: :iter:
Reference a Chapel function or iterator. The role text needs not include trailing parentheses to enhance readability.
These can also be used to reference a method or iterator on an object (class or record instance). The role text can include the type name and the method, in those cases. If it occurs within the description of a type, the type name can be omitted.
Dotted names may be used for any form.
:data: :const: :var: :param: :type:
Reference a module-level variable, constant, compiler param, or type.
:class: :record:
Reference a class or record; a dotted name may be used.
:attr:
Reference a data attribute (const, var, param, generic type) of an object.
For example:
Uses :proc:Random.RandomStream.fillRandom and real->int casts to
generate a vector of random integers. See :attr:RandomStream.seed
and description of :mod:Random for details on PRNG.
Relies on :iter:MyModule.Set.these to iterate over all values in the
given :record:MyModule.Set.
### Documenting argument, return, and yield values and types¶
Inside Chapel description directives, reST field lists with these fields are recognized and formatted nicely:
• arg, argument: Description of a parameter.
• type: Type of a parameter. Creates a link if possible.
• returns, return: Description of the return value.
• rtype: Return type. Creates a link if possible.
• yields, yield: Description of the yield value, often used for iterators.
• ytype: Yield type. Creates a link if possible.
type, rtype, and ytype should be concise and literal type definitions, like int, int(64), bool, [] int, RandomStream, etc. More verbose descriptions, qualifications, and limitations of those types should go in the corresponding arg, returns, or yields field.
For example, when documenting a Chapel proc:
/*
* Calculates number of pipes and returns fooy.
*
* :arg bars: Number of bars. Must be more than 1 and less than 1000.
* :type bars: int
*
* :arg hours: Hours available. Default is 1.0.
* :type hours: real
*
* :returns: Amount of fooy available.
* :rtype: Foo
*/
proc foo(bars, hours=1.0): Foo
{
...
}
Note
• Leave an empty line above and below all these fields for best results.
• All of these fields must be left-aligned with the outer most paragraph(s).
### Paragraph level markup¶
These directives create short paragraphs and can be used inside information units as well as normal text:
note
An especially important bit of information about an API that a user should be aware of when using whatever bit of API the note pertains to. The content of the directive should be written in complete sentences and include all appropriate punctuation.
Example:
.. note::
This function is not suitable for high precision calculations.
warning
An important bit of information about an API that a user should be aware of when using whatever bit of API the warning pertains to. The content of the directive should be written in complete sentences and include all appropriate punctuation. In the interest of not scaring users away from pages filled with warnings, this directive should only be chosen over note for information regarding the possibility of crashes, data loss, or security implications.
versionadded
This directive documents the version of Chapel which added the described feature, or a part of it, to the library or API. When this applies to an entire module, it should be placed at the top of the module section before any prose.
The first argument must be given and is the version in question; if the addition is only part of the described API element, you should add a second argument consisting of a brief explanation of the change.
Example:
.. versionadded:: 2.1
Note that there must be no blank line between the directive head and the explanation; this is to make these blocks visually continuous in the markup.
versionchanged
Similar to versionadded, but describes when and what changed in the named feature in some way (changed side effects, platform support, etc.). This one must have the second argument (explanation of the change).
seealso
Many sections include a list of references to module documentation or external documents. These lists are created using the seealso directive.
The seealso directive is typically placed in a section just before any sub-sections. For the HTML output, it is shown boxed off from the main flow of the text.
The content of the seealso directive should be a reST definition list. Example:
.. seealso::
Module :mod:Random
Documentation of the :mod:Random standard module.
Mersenne Twister pseudo random number generator <http://link>_
Documentation for the PRNG.
If you would like to restrict documentation to multi-line comments starting only with a special character sequence (say, /***) use the --docs-comment-style flag to indicate the desired prefix (e.g., --docs-comment-style='/***'). Setting a comment style in this way also establishes that the closing comment style should have the same number of characters (though they can be different ones).
## How chpldoc works¶
The Chapel standard library documentation is generated by running chpldoc over all Chapel source files in \$CHPL_HOME/modules/standard/.
The markup used in the comments is reStructuredText. reStructuredText is developed by the docutils projects and is amended by custom directives to support documenting Chapel code. Sphinx is used by chpldoc to render reStructuredText as HTML.
## Future directions¶
If there are other features you would like, please let us know. These are currently on our backlog:
• Expand visibility control (public/private) to remaining Chapel symbols (with options for including private elements in output if desired).
• Ability to include doctests, which would be code snippets in documentation that can be tested. This is similar to Python's doctest feature.
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http://motls.blogspot.com/2007/09/disinviting-larry-summers-mirror-for.html?m=0
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## Friday, September 21, 2007 ... /////
### Disinviting Larry Summers: a mirror for the far left
Lawrence Summers was invited to speak at University of California about competitiveness of the UC. He's quite an eloquent, engaging, and thoughtful speaker who has a lot of things to say and I am sure that many people wanted to hear him. Many other people would become happy after they would hear him. A third group would feel irritated but they would appreciate that they have learned a lot a few years later. And of course another group wouldn't ever find Summers' talk useful. That's how it always works.
However, a Maureen Stanton has decided that it shouldn't happen. She collected about 350 signatures of fellow Feminazis - the University of California is clearly an infinite heat bath of this stuff or, using the words of Santa Cruz Sentinel, a self-appointed cabal of leftist elitists - under a letter saying that Summers is a symbol of sexism whose visit is inappropriate.
What did the Regents do? Well, this question is really equivalent to the following one: is the Academia more influenced by top scholars, economists, and policymakers such as Lawrence Summers, or by hysterical far-left activists? As you know very well, this question is a rhetorical one. The answer is that the Academia - and University of California in particular - is controlled by a self-invited far-left thought police.
Everyone either agrees with them, or is so scared of them that he or she effectively agrees with them, or is eliminated. The result? Lawrence Summers was instantly disinvited. How does Regents chair Richard Blum justify his highly controversial disinvitation? "It is not an issue I want to deal with. There are many more important things to deal with." Well, your somewhat arrogant proclamation doesn't seem to be correct, Mr Blum. It is actually one of the most important things that UC administrators mustn't buckle to ideology because it would be at odds with everything a college should stand for.
Let us first discuss how the real world actually works and then we will have a look how it works under the control of a far-left political movement.
During a January 2005 conference about women in science that was overrun by politically correct pseudoscientists, Lawrence Summers very carefully suggested that the participants could perhaps think about the actual likely reasons behind the male-female cognitive differences that keep on surviving, despite 40 years (two generations) of aggressive affirmative action. Biological differences and different roles of men and women in families are among the first issues that must be considered.
It's a well-known story that the reaction of the politically correct "establishment" was explosive. Summers and all people who agree with him were ostracized, Summers was forced to resign one year later, and he was eventually replaced by a scholar who is not really comparable to Summers, to put it very mildly. As John Leo says, after Summers comes the Fall.
Is Maureen Stanton right? I personally find it alarming that a person as ignorant or blinded as Maureen Stanton has ever received a PhD from biology. I don't believe that anyone can understand what's really going on in biology if he or she can't figure out that millions of years of evolution have left different fingerprints on different groups of people (such as two sexes), or that hormones influence both anatomy as well as physiology of the brain. To make things worse, she is an "evolutionary biologist".
How can she be an evolutionary biologist if she doesn't get the simple fact that millions of years of evolution of humans - and tens of millions of years of evolution of mammals - have optimized men and women for different kinds of tasks? When one or two creationists who have made it through the university system end up with similar anti-evolution opinions because of their religious reasons, everyone is upset. When feminists end up with analogous unscientific opinions because of their feminist ideology, we're supposed not only to tolerate them but even promote their misunderstanding to the status of the only allowed "truth".
I think that granting her a PhD in 1980 was already an example of political correctness in action. But it was just a minor example. Political correctness and affirmative action have filled the Academia with thousands of people who shouldn't be there and who are starting to use their loud voices and immoral techniques to destroy basic principles of scholarship.
Many people often say that it doesn't hurt when extra people are admitted somewhere. It actually hurts a lot: the terror against people like Lawrence Summers - and be sure that his case is one of the more peaceful examples - is a part of the price for giving the likes of Maureen Stanton their PhD degrees and not only PhD degrees.
Freedom of expression
Let's not discuss biology because it is very clear that the people who prefer their egalitarian dogmas over very elementary facts about biology will continue to disagree. Instead, let us analyze the incident from the viewpoint of freedom of expression and a fair scholarly exchange of information.
There's no doubt that the decision of the Regents is shameful. Even if you disagreed that the biologically-driven cognitive differences between groups are a fact, it is certainly an opinion shared by dozens of percent of population and a similar percentage of scientists who can also back it up by quite some evidence. It is not acceptable for a university to be suppressing one kind of ideas in similar cases. Papers, talks, authors, and speakers must be judged and chosen according to their coherence, evidence, content, and other quality aspects instead of ideological colors.
In churches, political parties, and environmental movements, you can use an ideological key. And indeed, it is used all the time. But the standards of the Academia have been much more universal and fair at least for 7 centuries. What is happening right now is a brutal suppression of the basic values of scholarship and rational discourse in general, a decline of the Academia.
In the Academia, the sane, non-leftist people have effectively been exterminated. So let us talk about the leftists instead. Are they happy about the disinvitation? Well, there is no consensus about it but you will see that this fact is not such a good sign as you might a priori think.
For example, Bitch PhD writes an incoherent text about the topic whose only comprehensible component is the intriguing title: "Larry Summers: zombie or pirate?" In the comments, she explains that the right answer is probably "dick". She disagrees with some people who have criticized the disinvitation - such as Prof Eric Rauchway whom she considers a respectable "right-on feminist dude" - but her explanation makes no sense. So let's summarize: the most well-known female leftist Academic blogger in the U.S. - and I hope that she is going to be flattered by my posting - informs us in her latest work that Larry Summers is a dick. And she probably doesn't mean Dick Feynman even though Dick Feynman was a "sexist pig", too. ;-) This observation shouldn't be unexpected for those who know something about the feminist garbage that has filled the U.S. universities. Most feminists have similar qualities as this Dr Prostitute, at least when it comes close to any topic that is supposed to be covered by their favorite ideology.
Sean Carroll, another well-known far-left blogger, argues that the disinvitation was a mistake. But you shouldn't get too happy about his conclusion. If you read Carroll's explanation, you will see that the main thing he cares about is "the bad image it projects": conservatives may "beat the drum of leftist intolerance". Is it OK to conclude that according to Sean Carroll, if there were no conservatives who talk about these things, the "bad image problem" would go away and the leftists would be happily filtering all speakers, including former members of Democratic administrations, on an ideological basis?
Well, I happen to know that the answer is Yes. They have always done it whenever they were allowed to do so and I was "lucky" to live in one country where they did it for 41 years. This is an innate feature of all leftists. Leftist ideology is inherently totalitarian in character and it can't be otherwise. It's the very purpose of their ideology to control the whole society and to "optimize" it against the will, interests, opinions, and even scientific results of individuals and in contradiction to the values of a free society. Whenever the percentage of the true leftists gets above 15% or so, the society or organization is in big trouble because there is a "tipping point" or a "phase transition" above which the leftists are destined to take over the whole society or the whole organization.
I wonder how many more Stalins we will have to see before most people start to realize that the leftists are far greater a threat for the society than, for example, hungry grizzly bears or climate change. ;-)
And that's the memo.
P.S. If you worry about the freedom of speech, there are also good news. Mahmoud Ahmadinejad will be unanimously and enthusiastically welcome as a speaker at Columbia University; see this interview that Mahmoud considered to be non-interview. ;-) Peter Woit may show us a new map - gift from the president - without Israel that is not even wrong. Donald Rumsfeld's new job faces protests at Stanford but he still has an infinitesimal chance, despite 2500 signatures of haters. Erwin Chemerinsky may be re-elected as the dean because those who protested were not leftists but just some ordinary lawyers.
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http://su.diva-portal.org/smash/record.jsf?pid=diva2:446337
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Change search
Measurement of Spin Correlation in $t\bar{t}$ Production Using a Matrix Element Approach
Stockholm University, Faculty of Science, Department of Physics.
2011 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 107, no 3, 032001- p.Article in journal (Refereed) Published
##### Abstract [en]
We determine the fraction of t (t) over bar events with spin correlation, assuming that the spin of the top quark is either correlated with the spin of the top antiquark as predicted by the standard model or is uncorrelated. For the first time we use a matrix-element-based approach to study t (t) over bar spin correlation. We use t (t) over bar -> W(+)bW(-)(b) over bar -> l(+)nu bl(-)(nu) over bar(b) over bar final states produced in p (p) over bar collisions at a center- of- mass energy root s = 1: 96 TeV, where l denotes an electron or a muon. The data correspond to an integrated luminosity of 5: 4 fb(-1) and were collected with the D0 detector at the Fermilab Tevatron collider. The result agrees with the standard model prediction. We exclude the hypothesis that the spins of the t (t) over bar are uncorrelated at the 97.7% C.L.
##### Place, publisher, year, edition, pages
2011. Vol. 107, no 3, 032001- p.
##### National Category
Subatomic Physics
Physics
##### Identifiers
ISI: 000292736700008OAI: oai:DiVA.org:su-63017DiVA: diva2:446337
D0
##### Funder
Swedish Research Council
##### Note
Publikationen har totalt 421 författare, V. Abazov et al.Available from: 2011-10-06 Created: 2011-10-06 Last updated: 2012-01-26Bibliographically approved
#### Open Access in DiVA
No full text
Publisher's full text
#### Search in DiVA
Åsman, Barbro
##### By organisation
Department of Physics
##### In the same journal
Physical Review Letters
##### On the subject
Subatomic Physics
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https://ivofilot.nl/posts/view/24/How+to+build+VASP+4.6.38+using+the+Intel+compiler
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2015-03-22
# Introduction
In my previous post, I explained how to build VASP using the GNU compilers. Here, I will show you how you can build VASP using the Intel Compilers. In principle, the Intel Compilers should give better performance for VASP on Intel processors.
# Step 0: Install the Intel Compilers
Install the Intel Compiler Suite in /opt/intel (this is the default setting). Please refer to the installation instructions given by Intel.
# Step 1: Load the Intel Compilers
source /opt/intel/composer_xe_2013_sp1/bin/compilervars.sh intel64
# Step 2: Compile the Intel FFTW wrappers
cd /opt/intel/composer_xe_2013_sp1/mkl/interfaces/fftw3xf
make libintel64
# Step 3: Compile the VASP libraries
tar -xvzf vasp.4.lib.tar.gz
cd vasp.4.lib
cp makefile.linux_ifc_P4 Makefile
and change the file so that FC is linking to ifort
.SUFFIXES: .inc .f .F
#-----------------------------------------------------------------------
# Makefile for Portland Group F90/HPF compiler
# the makefile was tested only under Linux on Intel platforms
# however it might work on other platforms as well
#
# this release of vasp.4.lib contains lapack v2.0
# this can be compiled with pgf90 compiler if the option -O1 is used
#
# Mind: one user reported that he had to copy preclib.F diolib.F
# dlexlib.F and drdatab.F to the directory vasp.4.4, compile the files
# there and link them directly into vasp
# for no obvious reason these files could not be linked from the library
#
#-----------------------------------------------------------------------
# C-preprocessor
CPP = gcc -E -P -C $*.F >$*.f
FC=ifort
CFLAGS = -O
FFLAGS = -O0 -FI
FREE = -FR
DOBJ = preclib.o timing_.o derrf_.o dclock_.o diolib.o dlexlib.o drdatab.o
and type
make
# Step 4: Compile VASP
source /opt/intel/impi/4.1.1.036/bin64/mpivars.sh
tar -xvzf vasp.4.6.tar.gz
cd vasp.4.6
cp makefile.linux_ifc_P4 Makefile
Alter the Makefile on the following points
and finally run make
make
when you get this error
mpif77 -fc=ifort -FR -names lowercase -assume byterecl -O3 -xAVX -c fftmpiw.f90
fftmpiw.f90(55): error #5102: Cannot open include file 'fftw3.f'
include 'fftw3.f'
--------------^
fftmpiw.f90(89): error #5102: Cannot open include file 'fftw3.f'
include 'fftw3.f'
--------------^
fftmpiw.f90(110): error #5102: Cannot open include file 'fftw3.f'
include 'fftw3.f'
--------------^
fftmpiw.f90(220): error #5102: Cannot open include file 'fftw3.f'
include 'fftw3.f'
--------------^
compilation aborted for fftmpiw.f90 (code 1)
make: *** [fftmpiw.o] Error 1
copy the header file
cp /opt/intel/mkl/include/fftw/fftw3.f .
and run make again
make
# Step 5: Testing our compilation and comparing against the GNU compilation
We have used three different models to check the computational efficiency of the Intel Compilations versus that of the GNU compilation:
• A single CO molecule in a large box (gamma-point calculation)
• A bulk Cu system
• A Fe5C2 (Hagg carbide) system
The results are the following:
System gcc-4.8.4 VASP 4.6.38 Intel VASP 4.6.38
CO 240.483 240.683
Cu 54.623 34.994
Fe5C2 907.617 656.705
Interestingly, the Intel compiler does not give significantly different result for the gamma-point calculation (CO molecule). However, the speed improvement for the other calculations is roughly 30%!
If you have questions or comments, feel free to drop a line! Like what you read? Share this page with your friends and colleagues.
### Comments
#### Drop a line
Question:
What is the answer to Three + Seven?
Please answer with a whole number, i.e. 2, 3, 5, 8,...
52537
9
28-07-2014
11486
0
30-06-2016
5721
0
29-12-2017
5495
0
27-12-2017
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http://www.gradesaver.com/textbooks/science/chemistry/chemistry-the-central-science-13th-edition/chapter-15-chemical-equilibrium-exercises-page-663/15-15f
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## Chemistry: The Central Science (13th Edition)
$Kc = [H+][OH-]$ heterogeneous
The expression for Kc is given by the concentration of the products raised to their stoichiometric coefficients divided by the concentration of the reactants raised to their coefficients. $Kc = [H+][OH-]$ There is no denominator because the only reactant is H2O (l) and we cannot have the concentration of a pure liquid. Since there are both liquids and aqueous solutions it is heterogeneous.
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https://stats.stackexchange.com/questions/412047/the-minimal-sufficient-statistic-of-fx-e-x-thetae-e-x-theta
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# The minimal sufficient statistic of $f(x) = e^{-(x-\theta)}e^{-e^{-(x-\theta)}}$
The Casella Berger (2002) solutions manual says that the minimal sufficient statistic for
$$f(x) = e^{-(x-\theta)}e^{-e^{-(x-\theta)}}, \qquad x\in \mathbb{R}$$
are the order statistics $$(X_{(1)},\dots,X_{(n)})$$. This confuses me because it can be written as
$$f(x) = e^{\theta}e^{-x}e^{-e^\theta{e^{-x}}}$$
Which seems to be in the form of a full-rank exponential family, with complete sufficient statistic $$T(X) = \sum_i e^{-X_i}$$, and hence $$T(X)$$ is minimal sufficient by Bahadur's theorem. $$T(X)$$ seems to achieve a much greater reduction in the data aswell, so that the order statistics cannot be minimal sufficient?
I wonder if there is a property of the PDF I am missing that means it's not actually exponential family?
• I think you're right. The full location-scale family Gumbel is not exponential family but the location-family with scale=1 as here would be. Jun 8, 2019 at 3:26
Indeed it is clear from the density of $$X_1,\ldots,X_n$$ that $$\sum\limits_{i=1}^n e^{-X_i}$$ is a minimal complete sufficient statistic for $$\theta$$ as the pdf is a member of a regular full-rank exponential family as you say:
\begin{align} f_{\theta}(x_1,\cdots,x_n)&=e^{-\sum\limits_{i=1}^n x_i+n\theta}\exp\left(-\sum_{i=1}^n e^{-(x_i-\theta)}\right) \\&=\exp\left(-e^{\theta}\sum_{i=1}^n e^{-x_i}+n\theta\right)e^{-\sum\limits_{i=1}^nx_i}\quad\small\text{ for all }(x_1,\ldots,x_n)\in\mathbb R^n\,,\,\theta\in\mathbb R \end{align}
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http://www.enotes.com/homework-help/find-equation-line-passes-through-point-5-2-216901
|
# Find the equation of the line passes through the point ( 5,-2) and parallel to the line : 2y-x = 5
hala718 | High School Teacher | (Level 1) Educator Emeritus
Posted on
First we will write the equation for the line in the standard format:
y-y1 = m(x-x1) where (x1,y1) any point passes through the line and m is the slope.
==> y--2 = m(x-5)
==> y+ 2 = m(x-5)
But given the the line 2y-x = 5 is perpendicular to the line.
Then the products of the slopes should be -1.
2y-x = 5
We will rewrite in slope form:
2y= x+ 5
==> y= (1/2)x + 5/2
Then the slpe = 1/2
==> 1/2* m = -1
==> m= -2
==> y+ 2 = -2(x-5)
==> y= -2x + 10 -2
==> y= -2x +8
giorgiana1976 | College Teacher | (Level 3) Valedictorian
Posted on
Two lines are parallel if and only if their slopes are equal or if the ratio of their correspondent coefficients are also equal.
We'll put the given equation into the standard form. For this reason, we'll isolate 2y to the left side:
2y = x + 5
We'll divide by 2:
y = x/2 + 5/2
We'll write the standard form of the equation of the parallel line and we'll identify the value of the slope for both lines.
y = mx + n
m1 = 1/2 and m2 = m
The slopes have like values.
m = 1/2
Now, we'll write the equtaion of the line that has the slope m=1/2 and it passes through the point (5,-2).
y - (-2) = (1/2)(x - 5)
y + 2 = x/2 - 5/2
y = x/2 - 5/2 - 2
y = x/2 - 9/2
2y = x - 9
2y - x + 9 = 0
The equation of the parallel line whose slope is m = 1/2 and it is passing through the point (5,-2) is 2y - x + 9 = 0.
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https://www.rdocumentation.org/packages/grid/versions/3.5.3/topics/grid.show.viewport
|
grid.show.viewport
0th
Percentile
Draw a Diagram of a Grid Viewport
This function uses Grid graphics to draw a diagram of a Grid viewport.
Keywords
dplot
Usage
grid.show.viewport(v, parent.layout = NULL, newpage = TRUE,
vp.ex = 0.8, border.fill="light grey",
vp.col="blue", vp.fill="light blue",
scale.col="red",
vp = NULL)
Arguments
v
A Grid viewport object.
parent.layout
A grid layout object. If this is not NULL and the viewport given in v has its location specified relative to the layout, then the diagram shows the layout and which cells v occupies within the layout.
newpage
A logical value to indicate whether to move to a new page before drawing the diagram.
vp.ex
positive number, typically in $(0,1]$, specifying the scaling of the layout.
border.fill
Colour to fill the border margin.
vp.col
Colour for the border of the viewport region.
vp.fill
Colour to fill the viewport region.
scale.col
Colour to draw the viewport axes.
vp
A Grid viewport object (or NULL).
Details
A viewport is created within vp to provide a margin for annotation, and the diagram is drawn within that new viewport. By default, the margin is filled with light grey, the new viewport is filled with white and framed with a black border, and the viewport region is filled with light blue and framed with a blue border. The diagram is annotated with the width and height (including units) of the viewport, the (x, y) location of the viewport, and the x- and y-scales of the viewport, using red lines and text.
Value
None.
Grid, viewport
library(grid) # NOT RUN { ## Diagram of a sample viewport grid.show.viewport(viewport(x=0.6, y=0.6, w=unit(1, "inches"), h=unit(1, "inches"))) grid.show.viewport(viewport(layout.pos.row=2, layout.pos.col=2:3), grid.layout(3, 4)) # }
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|
https://api.philpapers.org/rec/BECKCF
|
# Kolmogorov complexity for possibly infinite computations
Abstract In this paper we study the Kolmogorov complexity for non-effective computations, that is, either halting or non-halting computations on Turing machines. This complexity function is defined as the length of the shortest input that produce a desired output via a possibly non-halting computation. Clearly this function gives a lower bound of the classical Kolmogorov complexity. In particular, if the machine is allowed to overwrite its output, this complexity coincides with the classical Kolmogorov complexity for halting computations relative to the first jump of the halting problem. However, on machines that cannot erase their output –called monotone machines–, we prove that our complexity for non effective computations and the classical Kolmogorov complexity separate as much as we want. We also consider the prefix-free complexity for possibly infinite computations. We study several properties of the graph of these complexity functions and specially their oscillations with respect to the complexities for effective computations Keywords infinite computations Kolmogorov complexity monotone machines non-effective computations program-size complexity Turing machines Categories (categorize this paper) DOI 10.1007/s10849-005-2255-6 Options Mark as duplicate Export citation Request removal from index
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## References found in this work BETA
On Degrees of Unsolvability.J. R. Shoenfield - 1964 - Journal of Symbolic Logic 29 (4):203-204.
|
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|
https://science.sciencemag.org/content/343/6172/754.abstract
|
Report
# Designing Collective Behavior in a Termite-Inspired Robot Construction Team
See allHide authors and affiliations
Science 14 Feb 2014:
Vol. 343, Issue 6172, pp. 754-758
DOI: 10.1126/science.1245842
## Abstract
Complex systems are characterized by many independent components whose low-level actions produce collective high-level results. Predicting high-level results given low-level rules is a key open challenge; the inverse problem, finding low-level rules that give specific outcomes, is in general still less understood. We present a multi-agent construction system inspired by mound-building termites, solving such an inverse problem. A user specifies a desired structure, and the system automatically generates low-level rules for independent climbing robots that guarantee production of that structure. Robots use only local sensing and coordinate their activity via the shared environment. We demonstrate the approach via a physical realization with three autonomous climbing robots limited to onboard sensing. This work advances the aim of engineering complex systems that achieve specific human-designed goals.
## Robot Rules
In the case of mound-building termites, colonies comprising thousands of independently behaving insects build intricate structures, orders of magnitude larger than themselves, using indirect communication methods. In this process, known as stigmergy, local cues in the structure itself help to direct the workers. Werfel et al. (p. 754; see the Perspective by Korb) wanted to construct complex predetermined structures using autonomous robots. A successful system was designed so that for a given final structure, the robots followed basic rules or “structpaths” in order to complete the task.
View Full Text
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http://mathhelpforum.com/calculus/47804-limit-derivative.html
|
1. ## limit & derivative
hey guys having trouble with this question. any help?
Use f '(x) = lim h->0 f(x + h) - f(x)/h
to find dy/dx when y = 3x + 4.
much appreciated!
2. Originally Posted by jvignacio
hey guys having trouble with this question. any help?
Use f '(x) = lim h->0 f(x + h) - f(x)/h
to find dy/dx when y = 3x + 4.
much appreciated!
$f(x) = 3x + 4$.
$f(x + h) = 3(x + h) + 4$.
$f(x + h) - f(x) = 3h$.
$\frac{f(x+h)-f(x)}{h} = 3$.
$\lim_{h \rightarrow 0} \frac{f(x+h)-f(x)}{h} = \lim_{h \rightarrow 0} 3 = 3$.
3. Originally Posted by mr fantastic
$f(x) = 3x + 4$.
$f(x + h) = 3(x + h) + 4$.
$f(x + h) - f(x) = 3h$.
$\frac{f(x+h)-f(x)}{h} = 3$.
$\lim_{h \rightarrow 0} \frac{f(x+h)-f(x)}{h} = \lim_{h \rightarrow 0} 3 = 3$.
haha any way of explaining what u did ??? so i can do the others myself.
4. Originally Posted by jvignacio
haha any way of explaining what u did ??? so i can do the others myself.
That's about as plain as it will ever get! What don't you understand?
5. Originally Posted by mr fantastic
That's about as plain as it will ever get! What don't you understand?
actually its okay. i understand now. thank u
|
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http://link.springer.com/article/10.1007%2FBF00334039
|
, Volume 77, Issue 2, pp 231-240
# On the shape of the convex hull of random points
Rent the article at a discount
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## Summary
Denote by E n the convex hull of n points chosen uniformly and independently from the d-dimensional ball. Let Prob(d, n) denote the probability that E n has exactly n vertices. It is proved here that Prob(d, 2 d/2 d )→1 and Prob(d, 2 d/2 d (3/4)+ɛ)→0 for every fixed ɛ>0 when d→∞. The question whether E n is a k-neighbourly polytope is also investigated.
|
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http://mathoverflow.net/feeds/question/103561
|
On finding A-polynomials - MathOverflow most recent 30 from http://mathoverflow.net 2013-05-22T18:57:07Z http://mathoverflow.net/feeds/question/103561 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/103561/on-finding-a-polynomials On finding A-polynomials Satoshi Nawata 2012-07-30T23:38:32Z 2012-08-02T13:36:40Z <p>I have two questions to obtain the explicit forms of A-polynomials.</p> <p><a href="http://arxiv.org/abs/math/0401068" rel="nofollow">Takata</a> used the mathematica pacage qMultisum.m to obtain the recursion relation of the colored Jones polynomials for twist knots. As Stavros Garoufalidis and Xinyu Sun pointed out in <a href="http://de.arxiv.org/abs/0802.4074" rel="nofollow">this paper</a>, the simple use of the mathematica pacage qZeil.m, qMultisum.m does not give the recursion relation of minimal order. They made use of the method, so-called creative telescoping, to get the recursion relation of minimal order by using the certificat function.</p> <blockquote> <blockquote> <ol> <li>How do you implement this method in Mathematica, say, to get the recursion relation for $5_2$ and $6_1$ knots as in p.4 of <a href="http://de.arxiv.org/abs/0802.4074" rel="nofollow">the paper</a>?</li> </ol> </blockquote> </blockquote> <p>Recently, <a href="http://arxiv.org/abs/1205.1515v2" rel="nofollow">Gukov, Sulkowski and Fuji</a> conjecture that, in the limit, $$q = e^{\hbar} \to 1 \,, \qquad a = \text{fixed} \,, \qquad t = \text{fixed} \,, \qquad x = q^n = \text{fixed}$$ the $n$-colored superpolynomials $P_n (K;a,q,t)$ exhibit the following large color'' behavior: $$P_n (K;a,q,t) \;\overset{{n \to \infty \atop \hbar \to 0}}{\sim}\; \exp\left( \frac{1}{\hbar} \int \log y \frac{dx}{x} \,+\, \ldots \right)$$ where ellipsis stand for regular terms (as $\hbar \to 0$) and the leading term is given by the integral on the zero locus of the super-$A$-polynomial: $$A^{\text{super}} (x,y;a,t) \; = \; 0 \ .$$</p> <p>For example, the critical points of the leading term of colored superpolynomials of torus knots $T^{2,2p+1}$ are give by \begin{eqnarray} 1 \; &=& \; -\frac{t^{-2-2p}(x-z_0)z_0^{-1-2p}(-1+t^2z_0)(1+ at^3 xz_0)}{(-1+z_0)(atx+z_0)(-1 + t^2 x z_0)} \cr y(x,t,a)&=& \frac{a^p t^{2 + 2 p} (-1 + x) x^{1 + 2 p} (atx + z_0) (1 + a t^3 x z_0)}{(1 + a t^3 x) (x - z_0) (-1 + t^2 x z_0)} , \end{eqnarray} which is written in Eq.(2.35) and (2.36). By eliminating $z_0$, you will obtain the super-$A$-polynomials for torus knots $T^{2,2p+1}$. Off course, it should be doable in principle, but</p> <blockquote> <blockquote> <p>$2$. how can it be implemented explicitly to obtain the super-$A$-polynomials as in Table 5 of <a href="http://arxiv.org/abs/1205.1515v2" rel="nofollow">this paper</a>? In other words, how do you explicitly eliminate $z_0$ in such a way that you will obtain the super-$A$-polynomials?</p> </blockquote> </blockquote> <p>I have the same problem to obtain the $Q$-deformed $A$-polynomials from Eq.(A.21) in <a href="http://arxiv.org/abs/1203.2182v1" rel="nofollow">this paper</a>.</p>
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http://gmatclub.com/forum/worried-about-background-check-130009.html
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Intern
Joined: 01 Apr 2012
Posts: 22
Followers: 0
Kudos [?]: 2 [0], given: 2
1
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Longtime lurker here.
I was accepted into a top 10ish program and I've payed the deposit. This school doesn't use kroll or similar services to my knowledge,..but they may use other methods i'm unaware of. Anyway,..the problem is that I was notified late last year (just before submitting apps) that I was approved by management for a performance award that had a cash bonus w/ it. Naturally, I put this down in the awards and acheivements sections of the App. Well, I later found out (shortly before acceptance notification) that the award recommendation was "sent back" on a second level of evaluation (apparently there are 2 levels of approval i wasn't aware of). I did not put the cash reward in the compensation (because i didn't know how much i would be eligible for),...but I'm not sure what to do now. Should I let the school know? Or should I just leave it be (what if they find out)? Everything else in my app is air tight, compensation, employment dates, titles,.etc etc.
I mean if i don't say anything and they find out somehow it wouldn't look good.
Intern
Joined: 09 Jan 2012
Posts: 25
Followers: 0
Kudos [?]: 3 [0], given: 0
pze wrote:
Longtime lurker here.
I was accepted into a top 10ish program and I've payed the deposit. This school doesn't use kroll or similar services to my knowledge,..but they may use other methods i'm unaware of. Anyway,..the problem is that I was notified late last year (just before submitting apps) that I was approved by management for a performance award that had a cash bonus w/ it. Naturally, I put this down in the awards and acheivements sections of the App. Well, I later found out (shortly before acceptance notification) that the award recommendation was "sent back" on a second level of evaluation (apparently there are 2 levels of approval i wasn't aware of). I did not put the cash reward in the compensation (because i didn't know how much i would be eligible for),...but I'm not sure what to do now. Should I let the school know? Or should I just leave it be (what if they find out)? Everything else in my app is air tight, compensation, employment dates, titles,.etc etc.
I mean if i don't say anything and they find out somehow it wouldn't look good.
Sounds like you have a pretty reasonable explanation. If they find something amiss in your background check they are going to give you an opportunity to explain it. I wouldn't worry about it at all.
That being said, most of the background checks just check to verify that you were employed by the companies on your resume, basic things like that.
Intern
Joined: 01 Apr 2012
Posts: 22
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Kudos [?]: 2 [0], given: 2
thk wrote:
pze wrote:
Longtime lurker here.
I was accepted into a top 10ish program and I've payed the deposit. This school doesn't use kroll or similar services to my knowledge,..but they may use other methods i'm unaware of. Anyway,..the problem is that I was notified late last year (just before submitting apps) that I was approved by management for a performance award that had a cash bonus w/ it. Naturally, I put this down in the awards and acheivements sections of the App. Well, I later found out (shortly before acceptance notification) that the award recommendation was "sent back" on a second level of evaluation (apparently there are 2 levels of approval i wasn't aware of). I did not put the cash reward in the compensation (because i didn't know how much i would be eligible for),...but I'm not sure what to do now. Should I let the school know? Or should I just leave it be (what if they find out)? Everything else in my app is air tight, compensation, employment dates, titles,.etc etc.
I mean if i don't say anything and they find out somehow it wouldn't look good.
Sounds like you have a pretty reasonable explanation. If they find something amiss in your background check they are going to give you an opportunity to explain it. I wouldn't worry about it at all.
That being said, most of the background checks just check to verify that you were employed by the companies on your resume, basic things like that.
If they find out,..wouldn't they ask me why i didn't bring it to their attention when I realized what happened,...rather than wait for them to bring it up??
Also,..are you saying they don't check other areas of the app besides employment and education? I was led to believe that they can check every aspect from EC's to job duties/responsibilities....is that wrong?
Manager
Joined: 06 Feb 2012
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WE: Project Management (Other)
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I would personally bring it to their attention with supporting documentation that it was an honest mistake.
Put yourself at the place of the AdCom or alumnus at the interview...
It is the ethical thing to do.
_________________
Kudos is a great way to say Thank you...
Intern
Joined: 01 Apr 2012
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Kudos [?]: 2 [0], given: 2
Damn,...i really don't know what to do. I guess if they bring it up I can put them in contact w/ the employee who nominated me for the award. He can explain the situation cause he's privy to the details,...not sure documentation can be provided (possibly proprietary info that the company won't provide).
One of my recommenders is my manager,.....if they do a recommender check,..i wonder if they'll broach the subject w/ him.
Senior Manager
Status: schools I listed were for the evening programs, not FT
Joined: 16 Aug 2011
Posts: 389
Location: United States (VA)
GMAT 1: 640 Q47 V32
GMAT 2: 640 Q43 V34
GMAT 3: 660 Q43 V38
GPA: 3.1
WE: Research (Other)
Followers: 3
Kudos [?]: 46 [0], given: 50
If I were you I would not mention anything unless asked about it, assuming your school doesn't do background checks. It is possible that they may have verified your app already, so then I guess things are moot. If your school did such checks, then I would ask about the issue. Most schools that require a background check of some sort will probably have to be up front with you now on that process, and it wouldn't be exactly ethical that they try to hide it now anyway.
Intern
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novanative wrote:
If I were you I would not mention anything unless asked about it, assuming your school doesn't do background checks. It is possible that they may have verified your app already, so then I guess things are moot. If your school did such checks, then I would ask about the issue. Most schools that require a background check of some sort will probably have to be up front with you now on that process, and it wouldn't be exactly ethical that they try to hide it now anyway.
I actually found out that the school does not do a check through Kroll or similar services. And they don't ask admits to sign waivers for background checks. Nobody seems to know whether they do their own back end checks or not.
I think I'll speak to my manager about this,...let him know that I put down the award for an application (without being too specific about what the app was for) and if he gets called about it ask him to explain that it was approved on manager level but then rescinded at a higher level. I hope that will satisfy them.
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Nothing to worry about here. They are looking for serious breaches - "I graduated from Harvard" when Harvard has no record of you attending, "I have a 4.0" when in fact you have a 1.9 gpa.... that kind of thing. Either that or items that would perhaps suggest students / staff would be at risk or gross ethics questions ; previous convictions for felony battery, fraud, etc. It's not a witchhunt for minor discrepancies. I wouldn't loose one pico second of sleep here....
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Well, my problem is much smaller. My College notified me today that there were some technical errors in my transcript's translation (some misspellings, mistake in document number and incorrect use of english they are gladly improved for a hard-copy now) My grades etc are the same
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I got a question here. I started a small business some years before as stated in the resume but never registered it from start till end.
So should I discuss with the admission office on that issue? I did bring some products to show them in the interview. How should I handle this?
Thanks all!
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rhyme wrote:
Nothing to worry about here. They are looking for serious breaches - "I graduated from Harvard" when Harvard has no record of you attending, "I have a 4.0" when in fact you have a 1.9 gpa.... that kind of thing. Either that or items that would perhaps suggest students / staff would be at risk or gross ethics questions ; previous convictions for felony battery, fraud, etc. It's not a witchhunt for minor discrepancies. I wouldn't loose one pico second of sleep here....
Man, I really hope you're right.
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pze wrote:
rhyme wrote:
Nothing to worry about here. They are looking for serious breaches - "I graduated from Harvard" when Harvard has no record of you attending, "I have a 4.0" when in fact you have a 1.9 gpa.... that kind of thing. Either that or items that would perhaps suggest students / staff would be at risk or gross ethics questions ; previous convictions for felony battery, fraud, etc. It's not a witchhunt for minor discrepancies. I wouldn't loose one pico second of sleep here....
Man, I really hope you're right.
Provided your description of the issue is accurate, I'd comfortably put $10,000 in escrow tomorrow and bet you that I am. Intern Joined: 01 Apr 2012 Posts: 22 Followers: 0 Kudos [?]: 2 [0], given: 2 Re: Worried about background check [#permalink] 05 Apr 2012, 10:13 rhyme wrote: Provided your description of the issue is accurate, I'd comfortably put$10,000 in escrow tomorrow and bet you that I am.
haha, ok you seem confident. Are you confident because you don't think they'll dig that deep or you just don't think they'll care about that discrepancy? I know the school doesn't use a professional verification service. So if their admissions office is doing all the checking, does it mean they don't delve as deep? Either way,..the situation was basically as I described. My salary info, dates employed, companies worked for,...education history are all accurate.
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pze wrote:
rhyme wrote:
Provided your description of the issue is accurate, I'd comfortably put $10,000 in escrow tomorrow and bet you that I am. haha, ok you seem confident. Are you confident because you don't think they'll dig that deep or you just don't think they'll care about that discrepancy? I know the school doesn't use a professional verification service. So if their admissions office is doing all the checking, does it mean they don't delve as deep? Either way,..the situation was basically as I described. My salary info, dates employed, companies worked for,...education history are all accurate. Four reasons really. One, as your surmised... they simply dont have the time to validate every last little claim made, could you imagine how long it would take to check every one of an applicants items - every grade, every title, every salary, every extracurricular, every award, hours volunteered, money donated, roles obtained, responsibilities, etc? You could easily spend a week on each student and still have dozens on unverifiable items left over. Two, there's almost no way to find out about this gap anyway. Who would tell them exactly? Its rather unlikely that HR has a list of who has received what award by whom Third, even if they do discover this potential gap (which, again, I dont see how) there's a simple and entirely verifiable explanation for the discrepancy anyway; so its a non-issue Fourth, by and large, most of this stuff goes through HR; and, at least in the US, what HR can legally disclose is very narrow. Even if they were AWARE of your receiving an award, which they likely would not be, they in all likelihood cant say much more than your salary, title and dates of employment. Intern Joined: 01 Apr 2012 Posts: 22 Followers: 0 Kudos [?]: 2 [0], given: 2 Re: Worried about background check [#permalink] 05 Apr 2012, 11:04 rhyme wrote: pze wrote: rhyme wrote: Provided your description of the issue is accurate, I'd comfortably put$10,000 in escrow tomorrow and bet you that I am.
haha, ok you seem confident. Are you confident because you don't think they'll dig that deep or you just don't think they'll care about that discrepancy? I know the school doesn't use a professional verification service. So if their admissions office is doing all the checking, does it mean they don't delve as deep? Either way,..the situation was basically as I described. My salary info, dates employed, companies worked for,...education history are all accurate.
Four reasons really.
One, as your surmised... they simply dont have the time to validate every last little claim made, could you imagine how long it would take to check every one of an applicants items - every grade, every title, every salary, every extracurricular, every award, hours volunteered, money donated, roles obtained, responsibilities, etc? You could easily spend a week on each student and still have dozens on unverifiable items left over.
Two, there's almost no way to find out about this gap anyway. Who would tell them exactly? Its rather unlikely that HR has a list of who has received what award by whom
Third, even if they do discover this potential gap (which, again, I dont see how) there's a simple and entirely verifiable explanation for the discrepancy anyway; so its a non-issue
Fourth, by and large, most of this stuff goes through HR; and, at least in the US, what HR can legally disclose is very narrow. Even if they were AWARE of your receiving an award, which they likely would not be, they in all likelihood cant say much more than your salary, title and dates of employment.
Yeah, I never really thought that HR would disclose that,..I was worried because my manager is also one of my recommenders,.....so in my worst fears I thought they might call him up and ask "Did you recommend pze? And oh,..did he receive this award?".
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you worry too much.
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I too am kind of worried. In one of my apps (very first one) I listed the wrong start date. I was off by around 6 months! I had inadvertantly included the time when I was interning there part time. Should I contact Adcom now and let them know (even before the background check starts)?
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I too am kind of worried. In one of my apps (very first one) I listed the wrong start date. I was off by around 6 months! I had inadvertantly included the time when I was interning there part time. Should I contact Adcom now and let them know (even before the background check starts)?
Did you get accepted to this school? If so, then if that school does the checks, then I think you should consider telling them but it doesn't appear to be an instance when you're trying to deceive the Adcom so you could let the background guys find out what they find. It's possible that HR may just say you started from when you interned and will just say that you still work there now, assuming you stayed at that same company. Generally HR will just say when you started, when you quit, and if asked, they may disclose your wage rate.
If you didn't get in the school yet and you know they do background checks, I'd wait it out and see what their first decision is. I wouldn't want to put attention to myself and at my app before a decision comes back.
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I've actually been admitted already. Just started to worry about this. I still work there and I am quite concerned if they will rescind the offer. My job titles are all correct and my salary info is also correct.
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I've actually been admitted already. Just started to worry about this. I still work there and I am quite concerned if they will rescind the offer. My job titles are all correct and my salary info is also correct.
I think you're fine either way. At the end of the day, every school you apply to has the right to do a reference check whenever they want to.
It's very rare that an admit will get his or her admission revoked unless the background check company finds out you blatantly lied all over your app. Also, most HR departments will only give you a neutral reference check, if you worked at more than one company pre-MBA. I think you just gave an honest mistake at worst.
Last edited by novanative on 05 Apr 2012, 21:01, edited 1 time in total.
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http://mathhelpforum.com/math-topics/167790-boundaries-print.html
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# Boundaries
• Jan 8th 2011, 11:17 AM
Natasha1
Boundaries
I never understand boundaries and would need some help on this question
In a race, Paula runs 25 laps of a track.
Each lap of the track is 400m, correct to the nearest metre.
Paula's average speed is 5.0 m/s, correct to one decimal place.
Calculate the upper bound for the time that Paula takes to run the race.
Give your answer in mins and seconds, correct ot the nearest second!
• Jan 8th 2011, 11:34 AM
snowtea
Upper bound for time is found using the lower bound on average speed and upper bound on track length.
I'm not sure what correct to one decimal place means.
If this means the digit is correct, then the average speed lower bound is 5.0m/s.
If it means correct rounded to 1 decimal place, then the average speed lower bound is 4.95 m/s.
If it means with an error of 0.1 m/s, then 4.9 m/s.
Upper bound on track distance is 401m.
• Jan 8th 2011, 11:38 AM
Natasha1
so I do 401 divide by 4.95 which gives me 81.01010101 mins/sec is this correct? And are the units correct too?
• Jan 8th 2011, 11:41 AM
snowtea
I think you have the right idea.
$time = distance / (avg\, speed)$, so you want to maximize distance and minimize average speed to get maximum time.
Units for time should be seconds.
• Jan 8th 2011, 11:43 AM
Natasha1
so time = 81 seconds
• Jan 8th 2011, 11:48 AM
snowtea
Quote:
Originally Posted by Natasha1
so time = 81 seconds
Close. Is 81 an upper bound of 81.010101... ?
• Jan 8th 2011, 11:50 AM
Natasha1
I don't know
• Jan 8th 2011, 12:09 PM
snowtea
Is $81 \geq 81.010101...$?
• Jan 8th 2011, 12:11 PM
Natasha1
strickly smaller
• Jan 8th 2011, 12:25 PM
snowtea
The question says compute an upper bound for time.
How can 81 seconds be an upper bound, when you computed something larger than 81 seconds for your answer.
• Jan 8th 2011, 12:27 PM
Natasha1
Got it! It's 82 dooooooooohhhhhh!
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# M T
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250 Awfully sophisticated proof for simple facts 19 Commutator subgroup does not consist only of commutators? 17 Is there a version of inclusion/exclusion for vector spaces? 11 What is the categorical significance of the trivial $\mathfrak{g}$-module in the category of $\mathfrak{g}$-mod? 9 “Lie algebra” for a general group ?
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https://socratic.org/questions/when-n2-g-reacts-with-h2-g-to-form-nh3-g-92-2-kj-of-energy-are-evolved-for-each-
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# When N2(g) reacts with H2(g) to form NH3(g) , 92.2 kJ of energy are evolved for each mole of N2(g) that reacts.?
## Write a balanced thermochemical equation for the reaction with an energy term in kJ as part of the equation. Note that the answer box for the energy term is case sensitive. Use the SMALLEST INTEGER coefficients possible and put the energy term (including the units) in the last box on the appropriate side of the equation. If a box is not needed, leave it blank. ++__------+____
Mar 7, 2018
$\frac{1}{2} {N}_{2} \left(g\right) + \frac{3}{2} {H}_{2} \left(g\right) \rightarrow N {H}_{3} \left(g\right) + 46.1 \cdot k J$
#### Explanation:
And according to the terms of the question...
${N}_{2} \left(g\right) + 3 {H}_{2} \left(g\right) \rightarrow 2 N {H}_{3} \left(g\right) + 92.2 \cdot k J$
Enthalpy change is usually quoted per mole of reaction as written. Here it was specified that $92.2 \cdot k J$ is evolved per mole of dinitrogen...
For the lower reaction we could also write $\Delta {H}_{\text{rxn}}^{\circ} = - 92.2 \cdot k J \cdot m o {l}^{-} 1$...
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https://includestdio.com/6507.html
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# physical chemistry – How does oil on the surface of water prevent rust?
## The Question :
24 people think this question is useful
I distinctly remember a side-by-side comparison from a book where there are two nails submerged in water, in two beakers: one nail had a layer of oil on top of the water, and that nail didn’t rust; the other did.
It seems that oiling iron/steel products is supposed to prevent them from rusting: http://www.justanswer.com/home-improvement/0n1r2-does-olive-oil-prevent-rust.html https://outdoors.stackexchange.com/questions/1404/can-oiling-keep-tools-from-rusting
The explanation given, I think, is that the oil somehow prevents oxygen from reacting with the metal.
Can’t help but wonder why. Oxygen is a non-polar molecule, so it should actually dissolve better in oils (which are also non-polar) than in water (which is highly polar) and therefore allow more oxygen molecules to contact the iron (metal) surface in some sort of equilibrium.
Let’s say that the conductivity of water and its ability to form electrochemical chains between metals is irrelevant in this thought experiment (i.e., a nail submerged in water in a glass). From what I understand, the other key item that has an effect on the formation of rust in water is that the oxygen molecules have better contact with the iron surface.
This is supported by data: the concentration of oxygen in air is far higher than that in water. We know from experience, though, that wet iron rusts way quicker than dry iron does.
If I am reading it correctly, the same data shows higher oxygen concentrations in non-polar solvents than in water.
Here is the data: http://www.nist.gov/data/PDFfiles/jpcrd219.pdf
My question is:
How does oiling prevent rust?
Edit: For the sake of clarity, let’s say we use deionized water in a vacuum, drop in the nail, then put some oil (let’s say it’s caprylic acid) on it, and expose it to standard conditions.
• I suspect that the statement about “oxygen being non-polar” is irrelevant. Gas solubility in liquids follows different rules. E.g. salts dissolve better in warm water, and you can freeze them out, but gases dissolve better in cold water and you can boil them out.
• Did I get it right: You are comparing two metals that are BOTH in water. Just that one water has oil on it, while the other has not? So the question would be: How does a layer of oil on water prevent rust under the water?
• @AngeloFuchs I’m wondering if the nail was dropped in after the oil was put on top of the water, and was coated as it entered the beakert.
• @ChrisH Good question. That would explain it, but without further input from OP, we won’t know.
• You probably should make it clearer that the oil layer is above the water (and not surrounding the nail), since many answers seem to overlook that detail “one nail had a layer of oil on top”
16 people think this answer is useful
Well, I went and searched for the solubility of oxygen in water and oil, and found this summary paper on the NIST web site: “The Solubility of Oxygen and Ozone in Liquids” by Battino, Rettich and Tominaga, J. Phys. Chem.Ref. Data., vol 12, no. 2, 1983.
Conveniently, the paper gives solubility data for oxygen in both water and olive oil. The solubility is given both as molar fractions, and also as the Ostwald coefficient $L$, defined as the volume of gas absorbed per volume of absorbing liquid.
Given the very different molar volumes of water and olive oil, I believe the latter provides a much more useful comparison here. Comparing tables 1 (water; note the $10^2$ factor in the header) and 25 (olive oil) in the paper, we see that the Ostwald solubility coefficient for oxygen in water is about 2,000 times higher than in olive oil:
Temp. (K) | Temp. (°C) | L (water) | L (olive oil)
-----------+------------+-----------+---------------
298.15 | 25 | 310.4 | 0.1269
308.15 | 35 | 276.6 | 0.1326
318.15 | 45 | 254.5 | 0.1383
328.15 | 55 | 240.9 | 0.1441
So, yes, oxygen is a lot more soluble in water than in oil. But why?
Well, if this web site is to be believed, it’s because of the strong hydrogen bonding between water molecules, which causes even liquid water to maintain some degree of an ice-like lattice structure, with gaps that small gas molecules like $\ce{O2}$ can easily slip into. Once there, the gas becomes solvated, with the strongly polar water molecules inducing a temporary dipole in the $\ce{O2}$ molecule and thus creating an attractive Debye interaction. The overall solvation process is exothermic (i.e. releases heat), explaining why the solubility of oxygen in water decreases with temperature.
6 people think this answer is useful
Before you read this answer, please read the ChemWiki article on the corrosion of iron. This explains the normal (Earth-surface) process for iron rusting, which involves both oxygen and water. The water is a catalyst, but the oxygen is a reactant: the reaction consumes oxygen and will stop if it becomes unavailable.
Now, if you put a nail in a beaker, add enough water to completely cover the nail, and then add enough oil to completely cover the surface of the water, there won’t be enough oxygen dissolved in the water to rust the nail more than a little bit. The only way for more oxygen to get into the water is by diffusing through the oil. We can model this as a chain of equilibria:
$$\text{O}_2\,\text{(air)} \rightleftharpoons \text{O}_2\,\text{(oil)} \rightleftharpoons \text{O}_2\,\text{(water)} + \text{Fe}\,\text{(nail)} \rightleftharpoons \text{Fe}_2\text{O}_3\,\text{(rust)}$$
Thermodynamically, the equilibrium lies all the way to the right: completely rusted nail, having soaked up as much oxygen as possible, ultimately from the air. But, as described in Ilmari’s answer to this question, oxygen is much less soluble in oil than in water. Therefore, oxygen will diffuse through the oil layer very slowly, and that will be the rate-limiting step. The rate constants for the air⇌oil and oil⇌water steps will depend on which oil is used and how thick the oil layer is.
So what happens is, after most of the oxygen that was initially dissolved in the water has been consumed by the rust, the nail does continue to rust, but very slowly — only as fast as additional oxygen molecules can get through the oil layer.
3 people think this answer is useful
Oil does two things.
1. Prevents oxygen molecules from colliding with the surface of the metal.
2. More importantly, oil drives away water. Water promotes rust by creating miniature electrochemical cells on the surface of iron objects. A cartoon of one of these cells can be seen here: Electrochemical cell promoting rust
Another point. While I am unaware of how well oxygen dissolves in oil, I’d be interested to know how the higher viscosity of oil reduces the mobility of the oxygen dissolved in it, and possibly reduces the rate of rusting.
0 people think this answer is useful
It is likely that the water was boiled, removing any carbon dioxide and excess oxygen. The oil on one of the beakers acts as a protective layer and prevents any carbon dioxide or oxygen dissolving into the water of that beaker, which prevents rust. The other beaker however was exposed to the carbon dioxide and oxygen in the atmosphere, which would have dissolved, allowing rust.
For an iron nail to rust, there must be several things present. these include: oxygen, an anode (a metal that readily gives electrons, in this case iron), an electrolyte (a liquid that assists the flow of electrons), oxygen, and a cathode( a metal that readily receives electrons – this can be a less reactive metal nearby or in this case, another part of the iron itself)
The reason that iron is readily able to accept and give electrons is because it is in the transition metal group of the periodic table, meaning it has an outer valency of two or 3, (max valency 8, min valency 1) meaning it is able to both give OR take electrons to fill its outer shell.
When the iron nail comes into contact with the water that is exposed to carbon dioxide (beaker without oil) the carbon dioxide begins to dissolve, forming a weak carbonic acid. This carbonic acid is a good electrolyte and provides acidic conditions.(iron rusts faster in acidic conditions, due to the increased concentration of h+ atoms present, which draw electrons from the iron, due to their positive charge.) This begins dissolving the iron, while the water breaks down into hydrogen and oxygen(the hydrogen is slightly positive and the oxygen is slightly negative, due to the unequal sharing of electrons in water molecules). The oxygen bonds with the dissolved iron, forming iron oxide (rust – balanced scientific equation – $4 \text{Fe} + 3\text{O}_2 = 2 \text{Fe}_2\text{O}_3$). When this happens, electrons are freed from the anode portion of the iron and flow to the cathode portion.
This is a redox reaction. A redox reaction involves reduction and oxidation. reduction is the gaining of electrons and the loss of oxygen. Oxidation is the loss of electrons and the gain of oxygen. In this situation, the iron is oxidised and the $\text{O}_2$ is reduced.
Other ways to stop the rusting or iron include:
• electroplating, coating iron in a less reactive metal
• using a sacrificial anode
• attaching a more reactive metal that will preferentially oxidise (in this case the sacrificial anode would be the anode, and the iron would act solely as the cathode)
• galvanizing, coating in zinc (which acts almost the same way as a sacrificial anode)
• coating the iron in metal oil or plastic to prevent it coming into contact with oxygen and electrolytes
• putting it in an environment that is missing one of the components needed for rust (e.g the beaker covered in oil was missing excess oxygen, so the nail could not oxidize = rust)
• alloying, this is when iron is mixed with other metals that help stabilize it
To speed the rusting of iron you can
• put it in a more acidic environment as this increases the number of h+ ions, making the iron more susceptible to rust
• connect a less reactive metal, so that the iron acts solely as an anode in the oxidation process, losing its electrons and corroding, while the less reactive metal which was harder to remove electrons from, acts as the cathode, receiving the electrons lost by the iron.
Note: metals that are more reactive than iron include magnesium and zinc (slow rusting), and metals that are less reactive include copper and tin (speed rusting).
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https://edoc.unibas.ch/70030/
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# Comparison of fast boundary element methods on parametric surfaces
Harbrecht, Helmut and Peters, Michael. (2013) Comparison of fast boundary element methods on parametric surfaces. Preprints Fachbereich Mathematik, 2013 (01).
PDF - Published Version 5Mb
Official URL: https://edoc.unibas.ch/70030/
We compare fast black-box boundary element methods on parametric surfaces in $\mathbb{R}^3$. These are the adaptive cross approximation, the multipole method based on interpolation, and the wavelet Galerkin scheme. The surface representation by a piecewise smooth parameterization is in contrast to the common approximation of surfaces by panels. Nonetheless, parametric surface representations are easily accessible from Computer Aided Design (CAD) and are recently topic of the studies in isogeometric analysis. Especially, we can apply two-dimensional interpolation in the multipole method. A main feature of this approach is that the cluster bases and the respective moment matrices are independent of the geometry. This results in a superior compression of the far field compared to other cluster methods.
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http://mathhelpforum.com/number-theory/3997-another-proof.html
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# Math Help - Another proof
1. ## Another proof
I have to Prove (a+b)^2 + (b+c)^2 + (c+a)^2 >= 4(ab + bc + ac)
I multiplied out both sides and then move everything to the left, but I don't know what I should do after that.
2. Originally Posted by Nichelle14
I have to Prove (a+b)^2 + (b+c)^2 + (c+a)^2 >= 4(ab + bc + ac)
I multiplied out both sides and then move everything to the left, but I don't know what I should do after that.
$(a+b)^2 + (b+c)^2 + (c+a)^2$
$=2(a^2 + b^2 + c^2)+ 2(ab + bc + ca)$
$=(a^2 + b^2)+(b^2 + c^2)+(a^2 + c^2)+ 2(ab + bc + ca)$
$\geq4(ab + bc + ca)$
Keep Smiling
Malay
3. Originally Posted by Nichelle14
I have to Prove (a+b)^2 + (b+c)^2 + (c+a)^2 >= 4(ab + bc + ac)
I multiplied out both sides and then move everything to the left, but I don't know what I should do after that.
It is necessary and suffienct for,
$a^2+b^2+c^2\geq ab+ac+bc$
----
If you play your cards right this is the "Cauchy-Swarchtz Inequality".
Let,
$\bold{v}=(a,b,c)$
$\bold{u}=(b,c,a)$
Then,
$||\bold{u}||\cdot ||\bold{v}||\geq |\bold{u}\cdot \bold{v} |$
Now,
$
||\bold{u}||\cdot ||\bold{v}||=a^2+b^2+c^2$
And,
$|\bold{u}\cdot \bold{v} |=|ab+bc+ac|$
Thus,
$a^2+b^2+c^2\geq |ab+bc+ac|\geq ab+bc+ac$
4. Hello, Nichelle14!
Prove that: . $(a+b)^2 + (b+c)^2 + (c+a)^2\:\geq\:4(ab + bc + ac)$
I multiplied out both sides and then move everything to the left. . . . Not recommended
Multiply out the left side and we have:
. . $(a+b)^2 + (b+c)^2 + (c+a)^2\:=$ $\:2(a^2 + b^2+c^2) + 4(ab + bc + ac)$ LHS
Since $a,\,b,\,c$ are real numbers: . $a^2 + b^2 + c^2 \:\geq \:0$
Multiply by $2:\;\;2(a^2 + b^2 + c^2) \:\geq \:0$
Add $4(ab + bc + ac)$ to both sides:
. . $\underbrace{2(a^2 + b^2 + c^2) + 4(ab + bc + ac)} \:\geq\:4(ab + bc + ac)$
. . . . . . . . This is LHS
Therefore: . $(a+b)^2 + (b+c)^2 + (c+a)^2\;\geq\;4(ab + bc + ac)$
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http://mattdickenson.com/2013/01/11/why-does-manhattan-have-the-best-shrimp/
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I'll ask the question in the same form that I originally heard it: "Why does Manhattan have the best shrimp?"* It makes sense why Portland (Maine) or Boston would have great lobster--the shellfish are harvested nearby. But even though shrimping locations are far from New York City, Manhattan restaurants can regularly get high-quality, plump shrimp. Likewise for juicy red apples and other nice produce--all from many kilometers or even continents away. If the "buy local" movement is all its cracked up to be, shouldn't the location where these items are harvested be the best spot to purchase them rather than the concrete jungle?
The answer involves transportation costs. Put yourself in the shoes of a Central American farmer for a moment. You have harvested a bumper crop of avocados or bananas, or another perishable crop. In your local marketplace you can sell the produce for just the cost of gas for a large truck. However, so can every other farmer in the local growing area. That means your local market has a lot of bananas and avocados, which drives down the price. The same item you could sell for 10 cents near home might go for $0.50 to$1.00 in a large US city.**
Having decided to ship your goods to the States, you have to decide which ones to sell. Do you want to send the so-so items that will sell in the low end of the price range above? It would still be better than what you can get at home, but it would barely cover the additional shipping costs. Keep in mind that the cost to ship it won't depend on the quality of the product. It costs the same to send a box of rotting bananas as it does to send the world's greatest bananas. This is why it makes sense to send the best: since the costs of shipping are fixed, you might as well ship the product where you'll make the greatest profit.
In economics this is known as the Alchian-Allen theorem,*** which Wikipedia summarizes as:
It states that when the prices of two substitute goods, such as high and low grades of the same product, are both increased by a fixed per-unit amount such as a transportation cost or a lump-sum tax, consumption will shift toward the higher-grade product. This is true because the added per-unit amount decreases the relative price of the higher-grade product.
The moral of the story is that under linear transportation costs, it is profitable to send the highest quality goods to the market that is best able to pay for quality. This is why large cities in developed countries (especially in North America and Europe) can have excellent produce shipped in from virtually anywhere. In other words, it makes good economic sense for Manhattan to get the best shrimp.
I have never been to New York City or Boston, so I am largely speculating. Based on available evidence I believe they exist and have quality produce, as do other large cities I have visited such as San Francisco. American supermarkets in smaller cities have improved substantially over the last few decades, but not everyone can have the best.
** These numbers are made up. If you have data, let's talk.
*** There has been some controversy over the theorem, but more recent work supports it. Tyler Cowen has discussed it in a podcast with Russ Roberts and a paper with Alex Tabbarok.
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https://jp.mathworks.com/help/phased/ref/physconst.html
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# physconst
Physical constants
## Syntax
``const = physconst(name)``
## Description
example
````const = physconst(name)` returns the value of the physical constant `const` specified by the `name` argument.```
## Examples
collapse all
Determine the wavelength of a 1 GHz electromagnetic wave.
```freq = 1e9; lambda = physconst('LightSpeed')/freq```
```lambda = 0.2998 ```
Determine the thermal noise power per unit bandwidth in the in-phase (I) and quadrature (Q) channels of a receiver. Specify a receiver temperature of 290 K.
```T = 290; k = physconst('Boltzmann');```
Compute the noise power per unit bandwidth, split evenly between the I and Q channels. Units are in dB.
`Noise_power = 10*log10(k*T/2)`
```Noise_power = -206.9855 ```
## Input Arguments
collapse all
Name of physical constant, specified as `'Lightspeed'`, `'Boltzmann'`, or `'EarthRadius'`. See Physical Constants for a list of values for physical constants used in Phased Array System Toolbox™.
Example: `'Lightspeed'`
## Output Arguments
collapse all
Value of physical constant, returned as a real-valued scalar. All values are in SI units.
collapse all
### Physical Constants
This table lists the supported constants and their values in SI units.
ConstantDescriptionValue
`'LightSpeed'`Speed of light in vacuum299,792,458 m/s. Most commonly denoted by c.
`'Boltzmann'`Boltzmann constant relating kinetic energy to temperature$1.\text{3806504}×{10}^{-23}$ J/K. 2006 NIST value, most commonly denoted by k.
`'EarthRadius'`Mean radius of the Earth6,371,000 m
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http://alidoc.cern.ch/AliPhysics/vAN-20171211/_ali_central_m_c_multiplicity_task_8h.html
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#include "AliCentralMultiplicityTask.h"
#include "AliSPDMCTrackDensity.h"
This graph shows which files directly or indirectly include this file:
Go to the source code of this file.
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https://www.physicsforums.com/threads/is-this-correct.298861/
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# Is this correct
1. Mar 10, 2009
### afcwestwarrior
1/ ((t) (1 + 4t + 4t ^2)) + 4 / (1 + 4t + 4t ^2)
= 5/ ((t) (1 + 4t + 4t ^2))
Last edited: Mar 10, 2009
2. Mar 11, 2009
### Staff: Mentor
No, it's not correct. To add these two rational expressions you need to find the least common denominator.
3. Mar 11, 2009
### Staff: Mentor
Why are you posting these problems in the Calculus and Higher forum? They should go in the Precalculus forum.
4. Mar 11, 2009
### afcwestwarrior
Because my problem has to do with calculus.
Similar Discussions: Is this correct
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https://cloud.originlab.com/doc/LabTalk/guide/From-Set-vals-Dialog
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# 2.5.1.3 From Set Values Dialog
The Set Values Dialog is useful when calculations on a column of data are based on functions that may include references to other datasets.
The column designated by Set Values is filled with the result of an expression that you enter (the expression returns a dataset). The expression can be made to update automatically (Auto), when requested by the user (Manual), or not at all (None).
For more complex calculations, where a single expression is not adequate, a Before Formula Scripts panel in the dialog can include any LabTalk script.
Auto and Manual updates create lock icons, and respectively, at the top of the column. A green lock indicates updated data; A yellow lock indicates pending update; A red lock indicates broken functionality.
In cases where the code is self-referencial (i.e. the column to be set is included in the calculation) the Auto and Manual options are reset to None.
Below are two examples of script specifically for the Set Values Dialog. Typically short scripts are entered in this dialog.
### Expression using another column
While limited to expressions (the right side of an equation) as in:
// In column 3
// Scale a column - useful for fitting where very large
//or very small numbers are problematic
col(2)*1e6;
the conditional expression can be useful in some situations:
// Set negative values to zero
col(2)<0?0:col(2);
### Using Before Formula Scripts Section
In the Before Formula Scripts section of the Set Column Values dialog, a script can be entered that will be executed by Origin just before the formula itself is executed. This feature is useful for carrying out operations that properly setup the formula itself. The following example demonstrates the use of such a script:
// In column BaseNormal
// In the expression section ..
BN
// In the Before Formula Scripts section ..
range raR = col(Reading); // The signal
range raB = col(Baseline); // The Baseline
dataset BN;
BN = raR - raB; // Subtract the baseline from the signal
stats BN; // Get statistics of the result
BN /= (stats.max / 100); // Normalize to maximum value of 100
The following image is a screenshot of the code above entered into the Set Column Values dialog:
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https://www.newton.ac.uk/seminar/20150318113012301
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We consider a model of a population of fixed size $N$ in which each individual acquires beneficial mutations at rate $\mu$. Each individual dies at rate one, and when a death occurs, an individual is chosen with probability proportional to the individual's fitness to give birth. We obtain rigorous results for the rate at which mutations accumulate in the population, the distribution of the fitnesses of individuals in the population at a given time, and the genealogy of the population. Our results confirm predictions of Desai and Fisher (2007), Desai, Walczak, and Fisher (2013), and Neher and Hallatschek (2013).
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https://www.physicsforums.com/threads/surface-area-surface-of-revolution-discrepancy.61887/
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# Surface Area (Surface of Revolution) - Discrepancy
1. Jan 30, 2005
### DoubleMike
So this question has been bothering me for a very long time... but only recently have I mustered up courage to register to ask it.
Before though, let me draw a parallel analogy, so you can see where I'm coming from. When you take the volume of a region enclosed by one or more functions revolved about a line, either the method of diks or shells is used.
Let us examine the volume of a sphere. The simplest way to calculate the volume of a sphere of radius R is to use the disk method with limits of integration -R to R, in respect to either variable (due to the symmetry).
So in essence the Riemann sum is the addition of the volume of infinitely many cylinders. These have parallel sides to the axis of the sphere/integration. Though strictly speaking we are adding very small volumes, I'd rather think of it as adding an infinite number of areas. This goes well with my understanding of infinities (as I've entreated in the General Math Forum). If this is flawed however, please feel free to elucidate.
Anyway.... When asked to take the surface area of a sphere, my book goes about it a very strange method indeed. It breaks the sphere up into an infinite number of partial cones, and uses the formula of their lateral surface area. I understand why this works... it makes sense. But why won't this work:
Breaking the sphere up into an infinite number of cylinders, and using the surface area formula for those (translational surface of a circle).
Here I have supplied a picture of what I mean:
http://www.geocities.com/boeclan/sphere.jpg
That picture goes for both the surface area and volume integrals. In the case of volume, that is the correct cross-section, whereas for surface area it is not.
Why is it that the function's slope is ignored when calculating volume, but for surface area, one must use the circuitous method described by my book?
*edit = typo
2. Jan 30, 2005
### HallsofIvy
So what you are saying is that you are dividing the sphere into very thin disks, of height dh and radius "r" where, since the sphere is given by x2+ y2+ z2= R2, r= $\sqrt{R^2- y^2}$. The lateral area of such a cylinder is given by $2\pir dy= 2\pi\sqrt{R^2-y^2}dy. Integrate [itex]2\pi\int_{-R}^R\sqrt{R^2-y^2}dy$ and see what you get.
(If you are right, it will be 4πr2.)
3. Jan 31, 2005
### DoubleMike
Is the integral $2\pi\int_{-R}^R\sqrt{R^2-x^2}dx$?
How would go integrate that without resorting to trigonometric substitution?
Well anyway, I checked the above integral for a random radius and it differs from the actual surface area!
4. Jan 31, 2005
### dextercioby
Write it (leave the 2pi for the moment):
$$\int_{-R}^{+R} \frac{R^{2}-x^{2}}{\sqrt{R^{2}-x^{2}}} dx$$
and then use the fact that
$$\int \frac{du}{\sqrt{1-u^{2}}}=\arcsin u +C$$
and partial integration to get the result...
Daniel.
P.S.Use the fact that the integrand is even and change the lower integration limit correspondingly.
5. Jan 31, 2005
### mathwonk
a smarter way to do the surface area of a sphere is by analogy with the method you used for the volume, i.e. by finding the derivative of the volume formula.
i.e. if one grows the volume of a sphere outwards it follows that the derivative of the volume function is the area of a cylindrical slice. Thus the volume itself is the integral of the area formula for this cylindrical slice, the so called "cylindrical shells" method.
On the other hand if one grows the volume of a sphere radially, it follows that the derivative of the volume function, wrt the radius is the area function of the sphere. hence the derivative of volume wrt radius is area for a sphere.
now this does not help compute the volume since we are not given the area, but since we already know the volume it does let us compute area, i.e. the area formula for a sphere, is the derivative of (4/3)pi r^3, wrt r, namely 4pi r^2.
you might like to read up on pappus theorem as well, for another analog of computing area via slices.
Last edited: Feb 1, 2005
6. Jan 31, 2005
### DoubleMike
I'm not entirely sure I know what you mean by even integrand. Also, I think trigonometric substitution is simpler in this case, but I keep messing it up:
$2\pi\int_{-R}^R\sqrt{R^2-x^2}dx$
I constructed a triangle with hypothenuse R and legs x and $\sqrt{R^2-x^2}$
so $\sin\theta = \frac{\sqrt{R^2-x^2}}{R}$ and $\cos\theta = \frac{x}{R}$
hence $-R\sin\theta d\theta = dx$ and $R\sin\theta = \sqrt{R^2-x^2}$
after the appropriate substitutions I get
$2\pi R^2 \int_{0}^\pi \sin^2 \theta d\theta$
using a power reducing formula
$\pi R^2 \int_{0}^\pi 1+\cos 2\theta$
$\pi R^2 [\theta + \frac{1}{2}\sin 2\theta]_{0}^\pi$
$\pi R^2 [\pi + 0]$
$\pi^2 R^2$
I'm not entirely sure of my math there, I didn't get the correct answer before, and working it out on itex was even worse... I might very well be wrong.
Regardless, integrating on my calculator, the method of disks differs largely from the actual formula derived using the slope and lateral surface of cones. What gives?
Last edited: Jan 31, 2005
7. Jan 31, 2005
### Justin Lazear
You're integrating just fine. Your cylinders model is incorrect, though.
Your model doesn't account for the fact that the length element ds of the cylinder must be longer, since it's at an angle. Compare the arclength traced out by the circle in element dx at x = 0 and x = near R. The first is just about straight, but the second is at a large angle, so it also goes down a good bit in the length dx, and therefore it should be longer.
--J
8. Feb 1, 2005
### DoubleMike
Yeah I realize that, but why do you have to account for the angle when finding the surface area, whereas for volume you can pretty much ignore it?
I don't understand that, besides... As the differential of x approaches 0, the significance of slope should be negligible.
9. Feb 1, 2005
### Justin Lazear
You do have to account for it. That's why when you change to cylindrical coordinates you get an $r d\theta$ term or an $r^2 \sin{\theta} dr d\theta$ term in spherical coordinates.
--J
10. Feb 1, 2005
### mathwonk
i am trying to actually answer the question of how to view the calculation of surface area as analogous to that of volume, but i do not seem to be making any impression on the questioner. oh well. cest la vie. people would rather calculate than think.
11. Feb 1, 2005
### Justin Lazear
Thinking is hard. Calculating is easy. Or at least that's what's taught in high school.
--J
12. Feb 2, 2005
### DoubleMike
I'm not sure whether to be insulted or not... Perhaps a better explanation is in order...
As it stands, I have to yet see a reason why I have to account for the curvature (besides the fact that the numbers don't match up). Yeah I understand that the curvature becomes more and more severe... But this never seemed to be a problem for calculating volume... And even if it is, why is it that $\pi \int_{-R}^R R^2-X^2 dx$ is a valid integral for volume? I don't see any reference to the slope of line tangent to the sphere's surface...
13. Feb 2, 2005
### mathwonk
Last edited: Feb 2, 2005
14. Feb 2, 2005
### DoubleMike
Ok, slow down.. Let's make up. I'm sorry I didn't read your post as carefully as I should have.
I understand what you're saying though, I had thought about it before (I fancied it suspicious that the derivative of volume happened to be the surface area.) I haven't done anything with spherical coordinates yet, but I follow the reasoning.
But still, that doesn't explain why breaking the sphere into small cylindrical segments and taking their lateral surface area doesn't work.
I know that the curvature is important, but there is nothing in the volume's Riemann sum that refers to it... So why should surface area be any different?
15. Feb 2, 2005
### Justin Lazear
The slope of the lines in the Cartesian coordinate system is always 1! dxdydz is always just a big box! As I said before, the case is not the same for coordinate systems where your dV element is not always just a big (edit: little) box, and in those coordinate systems, you do have to account for curvature.
--J
16. Feb 2, 2005
### mathwonk
what i am saying is there is no reason why what you suggested should work, since it is not really analogous to the method of calculating volume. in my post i give two methods which ARE analogous. i.e. if one works so should the other.
in your post, you give two rather different methods and ask why one works and the other does not. i ask you to think about why the area computation you suggest should work. i.e. what does it have in common with the shells method of computing volume?
and i apologize for getting my nose in a snit. i tried to edit but too slowly.
ill be back later but right now duke / wake is on.
Last edited: Feb 2, 2005
17. Feb 2, 2005
### DoubleMike
Ok, so perhaps a better question to ask it why the volume of sphere doesn't require that argument.
as it stands the Riemann sum is
$\pi\sum (R^2 - x^2) \delta x$ (not sure how to make the triangle on itex)
why not a sum of some function that takes the arguments radius and slope to calculate the volume of infinitely small cone sections?
$\pi\sum f(x, \frac{dy}{dx}) \delta x$
though it came to my mind that the function for the volume of a cone was derived using disks, so it too would be compromised.
Anyway, the point being that for a sphere, as you sum up the disks, shouldn't the fact that they have parallel sides skew the integral? (Because they don't follow the sphere's curvature.)
I don't know how to express my question!
Last edited: Feb 2, 2005
18. Feb 2, 2005
### mathwonk
what i mean is that calculating voluimes has nothing to do with approximations by cylinders or disks, it has to do with defining a growing volume function along some axis or other, and finding the derivative. if you consider a family of discs with enlarging radii, centered along the z axis, and let V(r) be the volume of your figure intersected with the solid cylinder of radius r, then the derivative is the area of the intersection of your figure intersected with the shell of radius r. this is called the method of cylindrical shells.
On the other hand if you consider a growing cylinder of fixed radius and growing height, intersected with your figure, then the derivative wrt height is the area of your figure intersected with the top circle of the cylinder of than height. then it is called the method of discs.
If you consider a famliy of solid spheres growing radially outward, intersected with your figure, then the derivative is the area of you figure with the surface area of the sphere of that radius. this method is not usually taught hence has no name.
But basically these methods for finding volumes have nothing to do with the shape of the family of figures that are growing, only with the relationship between their volume and the area of their leading face. I.e. these methods of calculating volumes are based on the fact that the derivative of a growing family of volumes is the surface area of the leading face of the family of figures. (provided the leading face is perpendicular to the direction of growth.)
In Pappus method for instance, we grow the volume in a circle by revolving a disk about the z axis, and consider the intersection of our figure with the solid partial torus generated by revolving the disc through a given angle. the derivative is the intersection of our figure with the area of the leading face, i.e. the moving circle.
Thus this method is much smarter for computing the volume of a torus generated by revolving a circle, since the derivative, the area of the moving circle is constant. thus the volume is that area times the circumference of the circle of centers of the moving circles.
so the whole point is to come up with a moving volume function, actually compute its derivative, usually an area, and then integrate back to get the volume.
the fact that the usual moving volume functions have derivative either the area of a cyliunder or a disc, is due to lack of imagination of textbook writers.
In particualr, it is not a consequence of that accident that one should do all calculations by approximating things with discs and cylinders.
rather one should try to compute ones desired quantity by some kind of appropriate moving function to the given problem, and then try to figure out what its derivative is.
so for example to compute the area of a torus, generate by revolving a circle, the derivative is delta area/ delta circumference of path of revolution, = circumference of the circle being revolved, again a constant. so the area of a torus equals the length of the circle being revoolved times the circumference of the path of revolution.
this is pappus method from thousands of years before calculus, explained by virtue of newton's ideas from calculus.
these things are not explained well in textbooks because most textbook writers just copy what other writers have said, without thinking about it first.
the methjod of computing areas using tangential cones is based on another entirely different idea they do not choose to explain. the key point is that since nbow the approximating regions no longer lie inside the given region, they mkust at elast be tangent to it.
tyhere is abetter way to view it absed on aparmetrizations, and change of area formulas under paramewtrizations, but enoiugh for now.
your question by the way is very intelligent and shows wonderful curiosity.
Last edited: Feb 2, 2005
19. Feb 2, 2005
### mathwonk
so ultimately the point is to understand why things are true. as presented in some books, the volume calculation is just, well these cylinders approximate that volume so in the limit we get the actual volume. oh yeah? why? whats the proof?
if you actually understand the proof of why the cylinder calculation does give the volume, then try to make that same proof go through for area, you should see that something crucial is then missing in the second case.
of coure it helps if you have a definition of volume and area.
but the method i am giving comes equipped with an argument. i.e. define a volume function V(r) or V(z) or V(something), and then compoute dV/dsomething as an area. then integrate back to get volume.
in the books they are skipping the explanation of why the area of that cylinder or of that disc, is really dV/dr or dV/dz, for some volujme function.
But if it were not, then you not get volume by integrating it.
so in the case of surface area, you are trying to compute surface area as a limit of areas of a different type.
what if you approximated your surface by discs that stuck straight out of your surface? would the areas of those discs have any relation to the area of your surface?
the better analogy for your problem, is why does the computation of arclength work?
i.e. the computation of arclength does work by approximating the curve by straight lines.
now if you look under the radical of the integrand for arclength you will see that what is being integrated is the length of approximating tangent line segments to your curve.
this is the analogy that does generalize to surface area. i.e. if you approximate your aurface by tangential pieces of surface, then their areas will approximate the surface area.
best wishes.
sorry if these explanations are inadequate, but they are the best i have at the moment.
20. Feb 2, 2005
### mathwonk
actually the arclength anal;ogy completely explains the surface area method, since if a piece of tangential segment is a good approximation to the curve then the cone obtained by revolving it is a good approximation to the surface area of revolution.
i.e. if the arclength is the integral of ds then the surface area is the integral of 2piRds.
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If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 27. By how much do the two digits differ?
(A) 3
(B) 4
(C) 5
(D) 6
(E) 7
[Reveal] Spoiler: OA
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Walkabout wrote:
If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 27. By how much do the two digits differ?
(A) 3
(B) 4
(C) 5
(D) 6
(E) 7
Given that (10a + b) - (10b + a) = 27 --> 9a - 9b =27 --> a - b = 3.
Answer: A.
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runningguy wrote:
Bunuel wrote:
Walkabout wrote:
If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 27. By how much do the two digits differ?
(A) 3
(B) 4
(C) 5
(D) 6
(E) 7
Given that (10a + b) - (10b + a) = 27 --> 9a - 9b =27 --> a - b = 3.
Answer: A.
Do we use 10 because of the tens digit??
Yes, any two-digit integer ab can be expressed as 10a+b, for example: 45 = 10*4 + 5.
The same for 3, 4, 5, ... digit numbers. For example, 4-digit number 5,432 can be written as 5*1,000 + 4*100 + 3*10 + 2 = 5,432.
Hope it's clear.
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Re: If a two-digit positive integer has its digits reversed, the [#permalink]
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13 Oct 2013, 14:45
Bunuel wrote:
Walkabout wrote:
If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 27. By how much do the two digits differ?
(A) 3
(B) 4
(C) 5
(D) 6
(E) 7
Given that (10a + b) - (10b + a) = 27 --> 9a - 9b =27 --> a - b = 3.
Answer: A.
Do we use 10 because of the tens digit??
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12 Jan 2014, 15:28
Walkabout wrote:
If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 27. By how much do the two digits differ?
(A) 3
(B) 4
(C) 5
(D) 6
(E) 7
The answer has to be a factor of 27, the only option that's a factor of 27 is 3.
Sice $$(10x + y) - (10y + x) = 27$$, you can simplify this relationship by subtracting with a common factor --> 9x - 9y = 27 ---> 9(x - y) = 27 ---> here, you already notice that the difference has to be a factor of both 9 and 27, but you can simplify further ---> x - y = 3, and thus we have the answer.
But these last steps are superfluous if you already notice that the answer has to be a factor of 27, this way you save time without having to calculate.
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Re: If a two-digit positive integer has its digits reversed, the [#permalink]
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18 Feb 2015, 22:12
Expert's post
Hi All,
Even though this question might seem a little strange, you do NOT need to do any excessive math to get to the correct answer. With just a bit of 'playing around' you can use 'brute force' to get to the answer.
We're told that a 2-digit number has its digits reversed and the difference between those two numbers is 27.
IF we use....
11 and 11, then the difference is 0 - this is NOT a match
12 and 21, then the difference = 9 - this is NOT a match
13 and 31, then the difference = 18 - this is NOT a match (notice the pattern though? The difference keeps increasing by 9!!!!! I wonder what the next one will be???)
14 and 41, then the difference = 27 = this IS a match
The question asks for the difference in the two DIGITS. The difference between 1 and 4 is 3.
Final Answer:
[Reveal] Spoiler:
A
There are actually several ways to get to this answer: 14 and 41, 25 and 52, 36 and 63, 47 and 74, 58 and 85, 69 and 96.
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Re: If a two-digit positive integer has its digits reversed, the [#permalink]
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24 Nov 2015, 04:21
Hey guys,
I was wondering if it is true to say that for any AB and BA ==> 9 is always a factor of (A-B) or (B-A) which ever is bigger, and so we can directly divide 27/9 to yield 3
then we can check numbers for a match: 41-14 = 27
==>So if we were given AB - BA = 54 ==> 54/9 = 6
check numbers: 71- 17 = 54
Is this reasoning always correct?
Re: If a two-digit positive integer has its digits reversed, the [#permalink] 24 Nov 2015, 04:21
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Magnetic Dipole moment- The magnetic field, B due to a current loop carrying a current i of radius, R at a distance l along its axis is given by: B = $$\frac {μ_0 i R^2}{2(R^2~+~l^2 )^{\frac32}}$$ Now if we consider a point very far from the current loop such that l>>R, then we can approximate the field as: Derivation of Magnetic Dipole Moment Formula. dipole moment calculation example: how to find the dipole moment of a molecule: how to calculate dipole moment of a molecule: dipole moment unit conversion: how to find zero dipole moment: how to calculate dipole moment chemistry: formula for finding magnetic moment: Molecular dipole moments can be obtained from microwave spectra. Electric Dipole Moment calculator uses Electric Dipole Moment=Charge*Radius Charge to calculate the Electric Dipole Moment, The electric dipole moment is a measure of the separation of positive and negative electrical charges within a system. You can also see the magnitude of the dipole moment increases in the second calculation. This is very common in excited states. Continue reading below if you want to learn more about the moment of force, its formula, or how to find the moment of force with examples? 9 4 A ˚, determine magnitude of the charge on the oxygen atom in the water molecule. In presence of an electric field, the rotational energy levels of a gaseous polar molecule are split (The Stark effect) according to the square of the permanent electric dipole moment. General Discussion. Being vectors, these can reinforce or cancel each other, depending on the geometry of the molecule; it is therefore not uncommon for molecules Enter the desired operating frequency in megahertz to get a good starting length for a dipole in both feet and meters. If the net charge of the species to which you are computing the dipole moment is zero, then the origin will not matter. Permanent Dipole Moment Curves Of The Lowest 1 + , 1 -and Molecular Modelling Analysis Of The Metabolism Of Caffeine Dipole-bound Anions And Relations Simulations Of The Physical Origin Of Far-field. In general the transition dipole moment is a complex vector quantity that includes the phase factors associated with the two states. Molecular polarity depends on both individual bond polarities and molecular geometry, the latter of which we can predict using VSEPR theory. Leticia_Pasetto April 4, 2019, 1:47pm #1. Dipole moment calculation. From the bond angle and vector moment μ = e × l. Thus, e (charge) can be determined in e s u. This organic chemistry video tutorial provides a basic introduction into dipole moment and molecular polarity. Therefore, 1Debye = 10-18 esu cm = 3.336 × 10-30 coulomb meter. Dipole moments as vector sums In molecules containing more than one polar bond, the molecular dipole moment is just the vector combination of what can be regarded as individual "bond dipole moments". Dipole Antenna Calculator. Unit of µ = unit of charge × unit of length. The SI unit of dipole moment is the coulomb meter, which is much too large for use with molecules, so dipole moments are measured in debye (symbol D) where 1 D = 3.335641×103-30 C m. Chlorobenzene has a dipole moment of magnitude 1.5 D due to the polarized C-Cl bond. The net dipole points through oxygen down the y-axis in the negative direction. It is a measure of the system's overall polarity. 3D; 2D; Starting structure. Dipole moment ( μ) is the measure of net molecular polarity, and describes the charge separation in a molecule, where electron density is shared unequally between atoms. The Wire Size can range from 16 AWG to 12 AWG. Dipole Moment. Place a 1:1 Balun on the Antenna end of the Feedline. The ORCA documentation also seems to state that *** CIS RELAXED DENSITY *** indicates this is the TD-DFT dipole moment. of Structural Biology Weizmann Institute, 761000 Rehovot, Israel With this server you can discover if your protein might have an unusually large net charge or dipole moment, and how this might relate to specific structural features of the protein, and thereby its function. Enter the desired frequency and select the desired calculation from the drop box. The electric dipole moment lies at the heart of a widely used experimental method for probing the vibrational dynamics of a system. Dipole Moment Calculation presents the overall dipole moment of a molecule as a vector expressed in the principal axis frame. This calculator is designed to give the horizontal length of a particular dipole (including Tees) antenna, or one side of it, for the frequency chosen. In a polar molecule, electron density is unevenly distributed throughout the molecule, resulting in regions of partial negative charge and regions of partial positive charge. Support. 1) In order to compute the dipole moment, you need to first choose an origin. Mind: the calculation of the dipole (IDIPOL=1-4) requires a definition of the center of the cell, and results might differ for different positions. 5 o and O - H bond length is 0. The molecular dipole moment can be represented as the sum of the individual atomic dipole moments and the pairwise atomic dipole contributions. Menu. Let's suppose we put water on the xy-plane like so: The dipole moment is calculated by looking up the dipole moment contributions from each "O"-"H" bond, which are polar, and summing them to get the net dipole. Download Image. Dipole moment of H 2 O is 1.85 D. If bond angle is 1. The half-wave dipole is very simple to construct. The dipole moment is defined much more broadly than just (point or finite) dipoles consisting of oppositely-charged pairs ─ there's plenty of other distributions with the same or similar properties , and the dipole moment is still an important quantity even if the shape differs from that. Hence the calculation of dipole moment order = 10-10 × 10-8 = 10-18 esu = 1 Debye. Protein Dipole Moments Server Clifford Felder and Joel Sussman, Dept. Electric dipole moments calculated from atom charges compared to dipoles from the wavefunction. The larger the wire, the wider the bandwidth. Dipoles antennas are easy to build and can be very effective when placed half a wavelenth or more above ground. The electric dipole moment for a pair of opposite charges of magnitude q is defined as the magnitude of the charge times the distance between them and the defined direction is toward the positive charge. Dipole moment (μ) is the measure of net molecular polarity, and describes the charge separation in a molecule, where electron density is shared unequally between atoms. Each contribution is "1.5 D" (debyes). Notice that the magnitude of the electric dipole moment is completely dependent on the displacement such that the dipole gains more polarity as the two charges move further and further from one another. Viewed 83k times 9. Physikalisch-chemisches Praktikum I Dipole Moment { 2016 Assuming that the vectors P~, E~and E~ 0 are parallel, we can insert4into8to obtain the scalar relation E= ˙ 0 P 0 def= ˙ 0 (9) The electric eld Ein a dielectric can thus be treated the same way as a eld in vacuum. Dimension of the Dipole Moment. $\endgroup$ – Emilio Pisanty Apr 12 '18 at 16:27 The electric dipole moment is a measure of the charge distribution in a molecule. The measurements below are for building a simple Dipole Antenna. One debye corresponds to a dipole moment occurring between two charges of one ten billionth franklin (10-10 Fr) separated by distance of one agstrem (1 Å). Unit of dipole moment derived from the centimeter-gram-second system (CGS). For covalent molecules, calculation of dipole moment requires knowledge of partial charge on all atoms and their locations. 1 Coulomb Meter = 2.997920E+029 debye = 1.000000E+000 C.m = 2.997920E+011 Eu Active 2 years, 3 months ago. Like bonds, molecules can also be polar. A physical dipole consists of two equal and opposite point charges An electric dipole is a separation of positive and negative charges.The direction of an electric field is defined as the direction of the force on a positive charge. The antenna is designed to be fed with 50 or 75 Ohm Coax Cable of most any length with a Balun. Ask Question Asked 6 years, 5 months ago. 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http://core.materials.ac.uk/search/detail.php?id=1143
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# Notched zinc, broken by impact at room temperature
View at:
Resource type: Image
Description: This is a notched zinc specimen broken by impact at room temperature. It has failed by a cleavage mechanism. One can observe the cleavage planes clearly separated by regions of local shear, where the fracture path crosses to adjacent planes. The cleavage planes are atomically flat and are not associated with much plastic deformation. At low temperature metals having b.c.c. and h.c.p structures have insufficient independent slip systems operating and are brittle, fracturing by cleavage.
Keywords: alloy • cleavage • fracture • metal • zinc
Categories: Science approaches > Deformation & failure > Fracture
Science approaches > Microstructure
Materials > Metals & alloys > Other metals & alloys > Zinc & alloys
Testing, analysis & experimentation > Metallography
Scale > Micro
Created by: DoITPoMS, University of Cambridge
Prof T W Clyne, Department of Materials Science and Metallurgy, University of Cambridge
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http://eprint.iacr.org/2011/291/20110621:224443
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## Cryptology ePrint Archive: Report 2011/291
Leakage-Resilient Coin Tossing
Elette Boyle and Shafi Goldwasser and Yael Tauman Kalai
Abstract: The ability to collectively toss a common coin among $n$ parties in the presence of faults is an important primitive in the arsenal of randomized distributed protocols. In the case of dishonest majority, it was shown to be impossible to achieve less than $\frac{1}{r}$ bias in $O(r)$ rounds (Cleve STOC '86). In the case of honest majority, in contrast, unconditionally secure $O(1)$-round protocols for generating common perfectly {\it unbiased} coins follow from general completeness theorems on multi-party secure protocols in the perfectly secure channels model (e.g., BGW, CCD STOC '88).
However, in the multi-party protocols with faulty minority, parties need to generate and hold local secret values which are assumed to be {\it perfectly hidden} from malicious parties: an assumption which is crucial to proving the resulting common coin is unbiased. This assumption unfortunately does not seem to hold in practice, as attackers can launch side-channel attacks on the local state of honest parties and leak information on their secrets.
In this work, we present an $O(1)$-round protocol for collectively generating an unbiased common coin, in the presence of leakage on the local state of the honest parties. We tolerate $t \le (\frac{1}{3} - \epsilon) n$ computationally-unbounded Byzantine faults and in addition a $\Omega(1)$-fraction leakage on each (honest) party's secret state. Our results hold in the memory leakage model (of Akavia, Goldwasser, Vaikuntanathan '08) adapted to the distributed setting.
Another contribution of our work is a tool we use to achieve collective coin flipping -- {\it leakage-resilient verifiable secret sharing}. Informally, this is a variant of ordinary VSS in which secrecy guarantees are maintained even if information is leaked on individual shares of the secret.
Category / Keywords: cryptographic protocols / Leakage-resilient protocols, coin tossing, distributed computing
Date: received 1 Jun 2011, last revised 21 Jun 2011
Contact author: eboyle at mit edu
Available format(s): PDF | BibTeX Citation
[ Cryptology ePrint archive ]
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https://worldwidescience.org/topicpages/a/asymmetric+waveform+ion.html
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#### Sample records for asymmetric waveform ion
1. Behaviour of tetraalkylammonium ions in high-field asymmetric waveform ion mobility spectrometry.
Science.gov (United States)
Aksenov, Alexander A; Kapron, James T
2010-05-30
High-field asymmetric waveform ion mobility spectrometry (FAIMS) is an ion-filtering technique recently adapted for use with liquid chromatography/mass spectrometry (LC/MS) to remove interferences during analysis of complex matrices. This is the first systematic study of a series of singly charged tetraalkylammonium ions by FAIMS-MS. The compensation voltage (CV) is the DC offset of the waveform which permits the ion to emerge from FAIMS and it was determined for each member of the series under various conditions. The electrospray ionization conditions explored included spray voltage, vaporizer temperature, and sheath and auxiliary gas pressure. The FAIMS conditions explored included carrier gas flow rate, electrode temperature and composition of the carrier gas. Optimum desolvation was achieved using sufficient carrier gas (flow rate > or = 2 L/min) to ensure stable response. Low-mass ions (m/z 100-200) are more susceptible to changes in electrode temperature and gas composition than high mass ions (m/z 200-700). As a result of this study, ions are reliably analyzed using standard FAIMS conditions (dispersion voltage -5000 V, carrier gas flow rate 3 L/min, 50% helium/50%nitrogen, inner electrode temperature 70 degrees C and outer electrode temperature 90 degrees C). Variation of FAIMS conditions may be of great use for the separation of very low mass tetraalkylammonium (TAA) ions from other TAA ions. The FAIMS conditions do not appear to have a major effect on higher mass ions. Copyright 2010 John Wiley & Sons, Ltd.
2. High-field asymmetric waveform ion mobility spectrometry for mass spectrometry-based proteomics.
Science.gov (United States)
Swearingen, Kristian E; Moritz, Robert L
2012-10-01
High-field asymmetric waveform ion mobility spectrometry (FAIMS) is an atmospheric pressure ion mobility technique that separates gas-phase ions by their behavior in strong and weak electric fields. FAIMS is easily interfaced with electrospray ionization and has been implemented as an additional separation mode between liquid chromatography (LC) and mass spectrometry (MS) in proteomic studies. FAIMS separation is orthogonal to both LC and MS and is used as a means of on-line fractionation to improve the detection of peptides in complex samples. FAIMS improves dynamic range and concomitantly the detection limits of ions by filtering out chemical noise. FAIMS can also be used to remove interfering ion species and to select peptide charge states optimal for identification by tandem MS. Here, the authors review recent developments in LC-FAIMS-MS and its application to MS-based proteomics.
3. High Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) for Mass Spectrometry-Based Proteomics
Science.gov (United States)
Swearingen, Kristian E.; Moritz, Robert L.
2013-01-01
SUMMARY High field asymmetric waveform ion mobility spectrometry (FAIMS) is an atmospheric pressure ion mobility technique that separates gas-phase ions by their behavior in strong and weak electric fields. FAIMS is easily interfaced with electrospray ionization and has been implemented as an additional separation mode between liquid chromatography (LC) and mass spectrometry (MS) in proteomic studies. FAIMS separation is orthogonal to both LC and MS and is used as a means of on-line fractionation to improve detection of peptides in complex samples. FAIMS improves dynamic range and concomitantly the detection limits of ions by filtering out chemical noise. FAIMS can also be used to remove interfering ion species and to select peptide charge states optimal for identification by tandem MS. Here, we review recent developments in LC-FAIMS-MS and its application to MS-based proteomics. PMID:23194268
4. An intelligent detection method for high-field asymmetric waveform ion mobility spectrometry.
Science.gov (United States)
Li, Yue; Yu, Jianwen; Ruan, Zhiming; Chen, Chilai; Chen, Ran; Wang, Han; Liu, Youjiang; Wang, Xiaozhi; Li, Shan
2018-04-01
In conventional high-field asymmetric waveform ion mobility spectrometry signal acquisition, multi-cycle detection is time consuming and limits somewhat the technique's scope for rapid field detection. In this study, a novel intelligent detection approach has been developed in which a threshold was set on the relative error of α parameters, which can eliminate unnecessary time spent on detection. In this method, two full-spectrum scans were made in advance to obtain the estimated compensation voltage at different dispersion voltages, resulting in a narrowing down of the whole scan area to just the peak area(s) of interest. This intelligent detection method can reduce the detection time to 5-10% of that of the original full-spectrum scan in a single cycle.
5. Separation of Opiate Isomers Using Electrospray Ionization and Paper Spray Coupled to High-Field Asymmetric Waveform Ion Mobility Spectrometry
Science.gov (United States)
Manicke, Nicholas E.; Belford, Michael
2015-05-01
One limitation in the growing field of ambient or direct analysis methods is reduced selectivity caused by the elimination of chromatographic separations prior to mass spectrometric analysis. We explored the use of high-field asymmetric waveform ion mobility spectrometry (FAIMS), an ambient pressure ion mobility technique, to separate the closely related opiate isomers of morphine, hydromorphone, and norcodeine. These isomers cannot be distinguished by tandem mass spectrometry. Separation prior to MS analysis is, therefore, required to distinguish these compounds, which are important in clinical chemistry and toxicology. FAIMS was coupled to a triple quadrupole mass spectrometer, and ionization was performed using either a pneumatically assisted heated electrospray ionization source (H-ESI) or paper spray, a direct analysis method that has been applied to the direct analysis of dried blood spots and other complex samples. We found that FAIMS was capable of separating the three opiate structural isomers using both H-ESI and paper spray as the ionization source.
6. Performance enhancement of high-field asymmetric waveform ion mobility spectrometry by applying differential-RF-driven operation mode.
Science.gov (United States)
Zeng, Yue; Tang, Fei; Zhai, Yadong; Wang, Xiaohao
2017-09-01
The traditional operation mode of high-field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) uses a one-way radio frequency (RF) voltage input as the dispersion voltage. This requires a high voltage input and limits power consumption reduction and miniaturization of instruments. With higher dispersion voltages or larger compensation voltages, there also exist problems such as low signal intensity or the fact that the dispersion voltage is no longer much larger than the compensation voltage. In this paper, a differential-RF-driven operation mode of FAIMS is proposed. The two-way RF is used to generate the dispersion field, and a phase difference is added between the two RFs to generate a single step waveform field. Theoretical analysis, and experimental results from an ethanol sample, showed that the peak positions of the ion spectra changed linearly (R 2 = 0.9992) with the phase difference of the two RFs in the differential-RF-driven mode and that the peak intensity of the ion spectrum could be enhanced by more than eight times for ethanol ions. In this way, it is possible to convert the ion spectrum peaks outside the separation or compensation voltage range into a detectable range, by changing the phase difference. To produce the same separation electric field, the high-voltage direct current input voltage can be maximally reduced to half of that in the traditional operation mode. Without changing the drift region size or drift condition, the differential-RF-driven operation mode can reduce power consumption, increase signal-to-noise ratio, extend the application range of the dispersion voltage and compensation voltage, and improve FAIMS detection performance.
7. Large-scale analysis of peptide sequence variants: the case for high-field asymmetric waveform ion mobility spectrometry.
Science.gov (United States)
Creese, Andrew J; Smart, Jade; Cooper, Helen J
2013-05-21
Large scale analysis of proteins by mass spectrometry is becoming increasingly routine; however, the presence of peptide isomers remains a significant challenge for both identification and quantitation in proteomics. Classes of isomers include sequence inversions, structural isomers, and localization variants. In many cases, liquid chromatography is inadequate for separation of peptide isomers. The resulting tandem mass spectra are composite, containing fragments from multiple precursor ions. The benefits of high-field asymmetric waveform ion mobility spectrometry (FAIMS) for proteomics have been demonstrated by a number of groups, but previously work has focused on extending proteome coverage generally. Here, we present a systematic study of the benefits of FAIMS for a key challenge in proteomics, that of peptide isomers. We have applied FAIMS to the analysis of a phosphopeptide library comprising the sequences GPSGXVpSXAQLX(K/R) and SXPFKXpSPLXFG(K/R), where X = ADEFGLSTVY. The library has defined limits enabling us to make valid conclusions regarding FAIMS performance. The library contains numerous sequence inversions and structural isomers. In addition, there are large numbers of theoretical localization variants, allowing false localization rates to be determined. The FAIMS approach is compared with reversed-phase liquid chromatography and strong cation exchange chromatography. The FAIMS approach identified 35% of the peptide library, whereas LC-MS/MS alone identified 8% and LC-MS/MS with strong cation exchange chromatography prefractionation identified 17.3% of the library.
8. Characterization Of Commonly Encountered Explosives Using Highfield Asymmetric Waveform Ion Mobility Spectrometry Coupled With Mass Spectrometry
Science.gov (United States)
2007-05-01
symptoms depending on the relative concentration, even leading to death.32 2.4. Instrument Settings Both positive and negative ions can be formed...Detection Technology, pp. 619-633, 1992. 7. Osorio, Celia ; Gomez, Lewis M.; Hernandez, Samuel P.; Castro, Miguel E., Time-of- flight Mass Spectroscopy...vol. 15, pp. 1950-1952. 34. Federal Facilities Assessment Branch, Public Health Assessment, US Army Umatilla Depot Activity, Centers for Disease
9. Detection of chlorinated and brominated byproducts of drinking water disinfection using electrospray ionization-high-field asymmetric waveform ion mobility spectrometry-mass spectrometry.
Science.gov (United States)
Ells, B; Barnett, D A; Froese, K; Purves, R W; Hrudey, S; Guevremont, R
1999-10-15
The lower limit of detection for low molecular weight polar and ionic analytes using electrospray ionization-mass spectrometry (ESI-MS) is often severely compromised by an intense background that obscures ions of trace components in solution. Recently, a new technique, referred to as high-field asymmetric waveform ion mobility spectrometry (FAIMS), has been shown to separate gas-phase ions at atmospheric pressure and room temperature. A FAIMS instrument is an ion filter that may be tuned, by control of electrical voltages, to continuously transmit selected ions from a complex mixture. This capability offers significant advantages when FAIMS is coupled with ESI, a source that generates a wide variety of ions, including solvent clusters and salt adducts. In this report, the tandem arrangement of ESI-FAIMS-MS is used for the analysis of haloacetic acids, a class of disinfection byproducts regulated by the US EPA. FAIMS is shown to effectively discriminate against background ions resulting from the electrospray of tap water solutions containing the haloacetic acids. Consequently, mass spectra are simplified, the selectivity of the method is improved, and the limits of detection are lowered compared with conventional ESI-MS. The detection limits of ESI-FAIMS-MS for six haloacetic acids ranged between 0.5 and 4 ng/mL in 9:1 methanol/tap water (5 and 40 ng/mL in the original tap water samples) with no preconcentration, derivatization, or chromatographic separation prior to analysis.
10. Analysis of chemical warfare agents in food products by atmospheric pressure ionization-high field asymmetric waveform ion mobility spectrometry-mass spectrometry.
Science.gov (United States)
Kolakowski, Beata M; D'Agostino, Paul A; Chenier, Claude; Mester, Zoltán
2007-11-01
Flow injection high field asymmetric waveform ion mobility spectrometry (FAIMS)-mass spectrometry (MS) methodology was developed for the detection and identification of chemical warfare (CW) agents in spiked food products. The CW agents, soman (GD), sarin (GB), tabun (GA), cyclohexyl sarin (GF), and four hydrolysis products, ethylphosphonic acid (EPA), methylphosphonic acid (MPA), pinacolyl methylphosphonic acid (Pin MPA), and isopropyl methylphosphonic acid (IMPA) were separated and detected by positive ion and negative ion atmospheric pressure ionization-FAIMS-MS. Under optimized conditions, the compensation voltages were 7.2 V for GD, 8.0 V for GA, 7.2 V for GF, 7.6 V for GB, 18.2 V for EPA, 25.9 V for MPA, -1.9 V for PinMPA, and +6.8 V for IMPA. Sample preparation was kept to a minimum, resulting in analysis times of 3 min or less per sample. The developed methodology was evaluated by spiking bottled water, canola oil, cornmeal, and honey samples at low microgram per gram (or microg/mL) levels with the CW agents or CW agent hydrolysis products. The detection limits observed for the CW agents in the spiked food samples ranged from 3 to 15 ng/mL in bottled water, 1-33 ng/mL in canola oil, 1-34 ng/g in cornmeal, and 13-18 ng/g in honey. Detection limits were much higher for the CW agent hydrolysis products, with only MPA being detected in spiked honey samples.
11. Identification of N-nitrosamines in treated drinking water using nanoelectrospray ionization high-field asymmetric waveform ion mobility spectrometry with quadrupole time-of-flight mass spectrometry.
Science.gov (United States)
Zhao, Yuan Yuan; Liu, Xin; Boyd, Jessica M; Qin, Feng; Li, Jianjun; Li, Xing-Fang
2009-01-01
We report a nanoelectrospray ionization (nESI) with high-field asymmetric waveform ion mobility spectrometry (FAIMS) and tandem mass spectrometry (MS-MS) method for determination of small molecules of m/z 50 to 200 and its potential application in environmental analysis. Integration of nESI with FAIMS and MS-MS combines the advantages of these three techniques into one method. The nESI provides efficient sample introduction and ionization and allows for collection of multiple data from only microliters of samples. The FAIMS provides rapid separation, reduces or eliminates background interference, and improves the signal-to-noise ratio as much as 10-fold over nESI-MS-MS. The tandem quadrupole time-of-flight MS detection provides accurate mass and mass spectral measurements for structural identification. Characteristics of FAIMS compensation voltage (CV) spectra of seven nitrosamines, N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), N-nitrosodi-n-butylamine (NDBA), N-nitrosopiperidine (NPip), and N-nitrosopyrrolidine (NPyr), were analyzed. The optimal CV of the nitrosamines (at DV -4000 V) were: -1.6 V, NDBA; 2.6 V, NDPA; 6.6 V, NPip; 8.8 V, NDEA; 13.2 V, NPyr; 14.4 V, NMEA; and 19.4 V, NDMA. Fragmentation patterns of the seven nitrosamines in the nESI-FAIMS-MS-MS were also obtained. The specific CV and MS-MS spectra resulted in positive identification of NPyr and NPip in a treated water sample, demonstrating the potential application of this technique in environmental analysis.
12. Asymmetric ion trap
Science.gov (United States)
Barlow, Stephan E.; Alexander, Michael L.; Follansbee, James C.
1997-01-01
An ion trap having two end cap electrodes disposed asymmetrically about a center of a ring electrode. The inner surface of the end cap electrodes are conformed to an asymmetric pair of equipotential lines of the harmonic formed by the application of voltages to the electrodes. The asymmetry of the end cap electrodes allows ejection of charged species through the closer of the two electrodes which in turn allows for simultaneously detecting anions and cations expelled from the ion trap through the use of two detectors charged with opposite polarity.
13. Ion Motion Stability in Asymmetric Surface Electrode Ion Traps
Science.gov (United States)
2010-03-01
Many recently developed designs of the surface electrode ion traps for quantum information processing have asymmetry built into their geometries. The asymmetry helps rotate the trap axes to angles with respect to electrode surface that facilitate laser cooling of ions but introduces a relative angle between the RF and DC fields and invalidates the classical stability analysis of the symmetric case for which the equations of motion are decoupled. For asymmetric case the classical motion of a single ion is given by a coupled, multi-dimensional version of Mathieu's equation. In this poster we discuss the stability diagram of asymmetric surface traps by performing an approximate multiple scale perturbation analysis of the coupled Mathieu equations, and validate the results with numerical simulations. After obtaining the stability diagram for the linear fields, we simulate the motion of an ion in a given asymmetric surface trap, utilizing a method-of-moments calculation of the electrode fields. We obtain the stability diagram and compare it with the ideal case to find the region of validity. Finally, we compare the results of our stability analysis to experiments conducted on a microfabricated asymmetric surface trap.
14. Beam emittance and output waveforms of high-flux laser ion source
Energy Technology Data Exchange (ETDEWEB)
Nakajima, M.; Asahina, M.; Horioka, K. [Tokyo Inst. of Technology, Dept. of Energy Sciences, Yokohama, Kanagawa (Japan); Yoshida, M.; Hasegawa, J.; Ogawa, M. [Tokyo Inst. of Technology, Research Laboratory for Nuclear Reactors, Tokyo (Japan)
2002-06-01
A laser ion source with short drift distance has been developed for a driver of heavy ion fusion (HIF). It supplies a copper ion beam of 200 mA (255 mA/cm{sup 2}) with duration of 400 ns and beam emittance is about 0.8{pi} mm{center_dot}mrad. Moreover it has fast rising (30 ns), flat-top current waveform and a potential to deliver pure charge states between 1{sup +} - 3{sup +}. Experimental results indicate that the laser ion source is a good candidate for the HIF driver. (author)
15. Investigation of the LAPPS Ion Flux to a Surface Biased with an Arbitrary High Frequency Waveform
Science.gov (United States)
Blackwell, David; Walton, Scott; Leonhardt, Darrin; Murphy, Donald; Fernsler, Richard; Meger, Robert
2001-10-01
Materials etching using accelerated ions has become a widely used procedure in the semiconductor industry. Typically the substrate is biased with high frequency voltage waveforms, which cause the substrate to acquire a negative DC voltage to accelerate the ions. However, the ions do not reach the substrate as a monoenergetic beam. The ion energy distribution function (IEDF) is profoundly influenced by the frequency and shape of the applied waveform. At NRL, we have been experimenting with electron-beam produced plasmas as an alternative to radiofrequency (RF) driven discharges. The most promising of these sources is the hollow cathode driven \\underlineLarge \\underlineArea \\underlinePlasma \\underlineProcessing \\underlineSystem. This source is designed to produce large area (> 1 m^2), high density, uniform sheets of plasma. In this presentation we will show measurements of the ion energy distribution function (IEDF) from continuous and pulsed electron beam plasmas produced in 20-30 cm wide × 1 cm thick sheets by a 2 kV hollow cathode. The IEDF is obtained using a gridded energy analyzer incorporated into a biasable stage. The surface flux and IEDF as a function of the waveform input to the stage will be investigated by using various types of pulse functions and variable frequency RF voltages. Typical operating conditions are 15-20 millitorr of argon, oxygen, or nitrogen, and 150-200 Gauss magnetic field.
16. Influence of asymmetric etching on ion track shapes in polycarbonate
International Nuclear Information System (INIS)
Clochard, M.-C.; Wade, T.L.; Wegrowe, J.-E.; Balanzat, E.
2007-01-01
By combining low-energy ion irradiation with asymmetric etching, conical nanopores of controlled geometry can be etched in polycarbonate (PC). Cone bases vary from 0.5 to 1 μm. Top diameters down to 17 nm are reached. When etching from one side, the pH on the other side (bathed in neutral or acidic buffer) was monitored. Etching temperature ranged from 65 deg. C to 80 deg. C. Pore shape characterization was achieved by electro replication combined with SEM observation. The tip shape depended on whether an acidic buffer was used or not on the stopped side
17. Vinylimidazole-Based Asymmetric Ion Pair Comonomers: Synthesis, Polymerization Studies and Formation of Ionically Crosslinked PMMA
NARCIS (Netherlands)
Jana, S.; Vasantha, V.A.; Stubbs, L.P.; Parthiban, A.; Vancso, Gyula J.
2013-01-01
Vinylimidazole-based asymmetric ion pair comonomers (IPCs) which are free from nonpolymerizable counter ions have been synthesized, characterized and polymerized by free radical polymerization (FRP), atom transfer radical polymerization (ATRP), and reversible addition-fragmentation chain transfer
18. Experimental observation of current generation by asymmetrical heating of ions in a tokamak plasma
International Nuclear Information System (INIS)
Gahl, J.; Ishihara, O.; Wong, K.L.; Kristiansen, M.; Hagler, M.
1986-01-01
The first experimental observation of current generation by asymmetrical heating of ions is reported. Ions were asymmetrically heated by a unidirectional fast Alfven wave launched by a slow wave antenna inside a tokamak. Current generation was detected by measuring the asymmetry of the toroidal plasma current with probes at the top and bottom of the toroidal plasma column
19. Asymmetric ion transport through ion-channel-mimetic solid-state nanopores.
Science.gov (United States)
Guo, Wei; Tian, Ye; Jiang, Lei
2013-12-17
Both scientists and engineers are interested in the design and fabrication of synthetic nanofluidic architectures that mimic the gating functions of biological ion channels. The effort to build such structures requires interdisciplinary efforts at the intersection of chemistry, materials science, and nanotechnology. Biological ion channels and synthetic nanofluidic devices have some structural and chemical similarities, and therefore, they share some common features in regulating the traverse ionic flow. In the past decade, researchers have identified two asymmetric ion transport phenomena in synthetic nanofluidic structures, the rectified ionic current and the net diffusion current. The rectified ionic current is a diode-like current-voltage response that occurs when switching the voltage bias. This phenomenon indicates a preferential direction of transport in the nanofluidic system. The net diffusion current occurs as a direct product of charge selectivity and is generated from the asymmetric diffusion through charged nanofluidic channels. These new ion transport phenomena and the elaborate structures that occur in biology have inspired us to build functional nanofluidic devices for both fundamental research and practical applications. In this Account, we review our recent progress in the design and fabrication of biomimetic solid-state nanofluidic devices with asymmetric ion transport behavior. We demonstrate the origin of the rectified ionic current and the net diffusion current. We also identify several influential factors and discuss how to build these asymmetric features into nanofluidic systems by controlling (1) nanopore geometry, (2) surface charge distribution, (3) chemical composition, (4) channel wall wettability, (5) environmental pH, (6) electrolyte concentration gradient, and (7) ion mobility. In the case of the first four features, we build these asymmetric features directly into the nanofluidic structures. With the final three, we construct
20. Intrinsic potential of cell membranes: opposite effects of lipid transmembrane asymmetry and asymmetric salt ion distribution
DEFF Research Database (Denmark)
Gurtovenko, Andrey A; Vattulainen, Ilpo
2009-01-01
Using atomic-scale molecular dynamics simulations, we consider the intrinsic cell membrane potential that is found to originate from a subtle interplay between lipid transmembrane asymmetry and the asymmetric distribution of monovalent salt ions on the two sides of the cell membrane. It turns out......Cl saline solution and the PE leaflet is exposed to KCl, the outcome is that the effects of asymmetric lipid and salt ion distributions essentially cancel one another almost completely. Overall, our study highlights the complex nature of the intrinsic potential of cell membranes under physiological...... that both the asymmetric distribution of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) lipids across a membrane and the asymmetric distribution of NaCl and KCl induce nonzero drops in the transmembrane potential. However, these potential drops are opposite in sign. As the PC leaflet faces a Na...
1. Asymmetric Membranes Containing Micron-Size Silicon for High Performance Lithium Ion Battery Anode
International Nuclear Information System (INIS)
Byrd, Ian; Wu, Ji
2016-01-01
Micron-size Si anode is notorious for having extremely poor cycle life. It is mainly caused by the large volume change (∼300%) and poor mechanical strength of the Si electrode. Satisfying methods to address this issue are seriously lacking in literature. In this study, novel single-layer, double-layer and triple-layer asymmetric membranes containing micron-size silicon have been fabricated using a simple phase inversion method to dramatically improve its cyclability. The electrochemical performance of these asymmetric membranes as lithium ion battery anodes are evaluated and compared to pure micron-size Si powders and carbonaceous asymmetric membranes. All three types of asymmetric membrane electrodes demonstrate significantly enhanced stability as compared to pure Si powders. The single-layer asymmetric membrane has the largest capacity degradation due to the loss of pulverized Si powders from the membrane surface, only 40% of whose capacity can be retained in 100 cycles. But this performance is still much better than pure micron-size silicon electrode. After being coated with nanoporous carbonaceous layers on both sides of a single-layer asymmetric membrane to make a triple-layer asymmetric membrane (sandwich structure), the capacity retention is notably increased to 88% in 100 cycles at 610 mAh g"−"1 and 0.5C. The enhanced stability is attributed to the extra nanoporous coatings that can prevent the fractured Si powders from being leached out and allow facile lithium ion diffusions. Such a novel, efficient and scalable method may provide beneficiary guidance for designing high capacity lithium ion battery anodes with large volume change issues.
2. Measurement of asymmetric optical pumping of ions accelerating in a magnetic-field gradient
International Nuclear Information System (INIS)
Sun Xuan; Scime, Earl; Miah, Mahmood; Cohen, Samuel; Skiff, Frederick
2004-01-01
We report observations of asymmetric optical pumping of argon ions accelerating in a magnetic-field gradient. The signature is a difference in the laser-induced-fluorescence emission amplitude from a pair of Zeeman-split states. A model that reproduces the dependence of the asymmetry on magnetic-field and ion-velocity gradients is described. With the model, the fluorescence intensity ratio provides a new method of measuring ion collisionality. This phenomenon has implications for interpreting stellar plasma spectroscopy data which often exhibit unequal Zeeman state intensities
3. Measurement of Asymmetric Optical Pumping of Ions Accelerating in a Magnetic-field Gradient
Energy Technology Data Exchange (ETDEWEB)
Xuan Sun; Earl Scime; Mahmood Miah; Samuel Cohen; Frederick Skiff
2004-10-28
We report observations of asymmetric optical pumping of argon ions accelerating in a magnetic field gradient. The signature is a difference in the laser-induced-fluorescence (LIF) emission amplitude from a pair of Zeeman-split states. A model that reproduces the dependence of the asymmetry on magnetic-field and ion-velocity gradients is described. With the model, the fluorescence intensity ratio provides a new method of measuring ion collisionality. This phenomenon has implications for interpreting stellar plasma spectroscopy data which often exhibit unequal Zeeman state intensities.
4. Measurement of Asymmetric Optical Pumping of Ions Accelerating in a Magnetic-field Gradient
International Nuclear Information System (INIS)
Xuan Sun; Earl Scime; Mahmood Miah; Samuel Cohen; Frederick Skiff
2004-01-01
We report observations of asymmetric optical pumping of argon ions accelerating in a magnetic field gradient. The signature is a difference in the laser-induced-fluorescence (LIF) emission amplitude from a pair of Zeeman-split states. A model that reproduces the dependence of the asymmetry on magnetic-field and ion-velocity gradients is described. With the model, the fluorescence intensity ratio provides a new method of measuring ion collisionality. This phenomenon has implications for interpreting stellar plasma spectroscopy data which often exhibit unequal Zeeman state intensities
5. Selection and generation of waveforms for differential mobility spectrometry.
Science.gov (United States)
Krylov, Evgeny V; Coy, Stephen L; Vandermey, John; Schneider, Bradley B; Covey, Thomas R; Nazarov, Erkinjon G
2010-02-01
Devices based on differential mobility spectrometry (DMS) are used in a number of ways, including applications as ion prefilters for API-MS systems, as detectors or selectors in hybrid instruments (GC-DMS, DMS-IMS), and in standalone systems for chemical detection and identification. DMS ion separation is based on the relative difference between high field and low field ion mobility known as the alpha dependence, and requires the application of an intense asymmetric electric field known as the DMS separation field, typically in the megahertz frequency range. DMS performance depends on the waveform and on the magnitude of this separation field. In this paper, we analyze the relationship between separation waveform and DMS resolution and consider feasible separation field generators. We examine ideal and practical DMS separation field waveforms and discuss separation field generator circuit types and their implementations. To facilitate optimization of the generator designs, we present a set of relations that connect ion alpha dependence to DMS separation fields. Using these relationships we evaluate the DMS separation power of common generator types as a function of their waveform parameters. Optimal waveforms for the major types of DMS separation generators are determined for ions with various alpha dependences. These calculations are validated by comparison with experimental data.
6. Selection and generation of waveforms for differential mobility spectrometry
International Nuclear Information System (INIS)
Krylov, Evgeny V.; Coy, Stephen L.; Nazarov, Erkinjon G.; Vandermey, John; Schneider, Bradley B.; Covey, Thomas R.
2010-01-01
Devices based on differential mobility spectrometry (DMS) are used in a number of ways, including applications as ion prefilters for API-MS systems, as detectors or selectors in hybrid instruments (GC-DMS, DMS-IMS), and in standalone systems for chemical detection and identification. DMS ion separation is based on the relative difference between high field and low field ion mobility known as the alpha dependence, and requires the application of an intense asymmetric electric field known as the DMS separation field, typically in the megahertz frequency range. DMS performance depends on the waveform and on the magnitude of this separation field. In this paper, we analyze the relationship between separation waveform and DMS resolution and consider feasible separation field generators. We examine ideal and practical DMS separation field waveforms and discuss separation field generator circuit types and their implementations. To facilitate optimization of the generator designs, we present a set of relations that connect ion alpha dependence to DMS separation fields. Using these relationships we evaluate the DMS separation power of common generator types as a function of their waveform parameters. Optimal waveforms for the major types of DMS separation generators are determined for ions with various alpha dependences. These calculations are validated by comparison with experimental data.
7. Asymmetric Functional Conversion of Eubacterial Light-driven Ion Pumps*
Science.gov (United States)
Inoue, Keiichi; Nomura, Yurika; Kandori, Hideki
2016-01-01
In addition to the well-known light-driven outward proton pumps, novel ion-pumping rhodopsins functioning as outward Na+ and inward Cl− pumps have been recently found in eubacteria. They convert light energy into transmembrane electrochemical potential difference, similar to the prototypical archaeal H+ pump bacteriorhodopsin (BR) and Cl− pump halorhodopsin (HR). The H+, Na+, and Cl− pumps possess the conserved respective DTE, NDQ, and NTQ motifs in the helix C, which likely serve as their functional determinants. To verify this hypothesis, we attempted functional interconversion between selected pumps from each category by mutagenesis. Introduction of the proton-pumping motif resulted in successful Na+ → H+ functional conversion. Introduction of the respective characteristic motifs with several additional mutations leads to successful Na+ → Cl− and Cl− → H+ functional conversions, whereas remaining conversions (H+ → Na+, H+ → Cl−, Cl− → Na+) were unsuccessful when mutagenesis of 4–6 residues was used. Phylogenetic analysis suggests that a H+ pump is the common ancestor of all of these rhodopsins, from which Cl− pumps emerged followed by Na+ pumps. We propose that successful functional conversions of these ion pumps are achieved exclusively when mutagenesis reverses the evolutionary amino acid sequence changes. Dependence of the observed functional conversions on the direction of evolution strongly suggests that the essential structural mechanism of an ancestral function is retained even after the gain of a new function during natural evolution, which can be evoked by a few mutations. By contrast, the gain of a new function needs accumulation of multiple mutations, which may not be easily reproduced by limited mutagenesis in vitro. PMID:26929409
8. Effect of multipulse waveform on gains of soft X-ray lines of lithium-like aluminum ions in recombining plasmas
International Nuclear Information System (INIS)
Okasaka, Kazunobu; Hara, Tamio; Yamaguchi, Naohiro; Ando, Kozo; Kawachi, Tetsuya; Oyama, Hitoshi
2000-01-01
Using the recombination plasma scheme, we investigated the amplified spontaneous emissions (ASE) from lithium-like aluminum plasmas produced by multipulse laser irradiation. Three types of multipulse waveforms of Nd-glass laser beam were treated. We measured the time-integrated intensities of the 3d-4f (15.5 nm) and the 3d-5f (10.6 nm) lines of lithium-like aluminum ions for 2.5-cm-long and 1.25-cm-long plasmas. The effective time-averaged gains estimated from these time-integrated intensities varied with the multipulse waveforms. using a hydrodynamic simulation, we discussed the time history of plasma parameters in the recombining plasma. We concluded that the modifying multipulse waveform contributed to the effective time-averaged gain by maintaining the helium-like ion density until the gain was generated. (author)
9. A novel vanadium oxide deposit for the cathode of asymmetric lithium-ion supercapacitors
Energy Technology Data Exchange (ETDEWEB)
Li, Jing-Mei; Hu, Chi-Chang [Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu (China); Chang, Kuo-Hsin [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi (China)
2010-12-15
Hydrous vanadium oxide (denoted as VO{sub x}.yH{sub 2}O) deposited at 0.4 V shows promising capacitive behavior in aqueous media containing concentrated Li ions. VO{sub x}.yH{sub 2}O annealed in air at 300 C for 1 h shows highly reversible Li-ion intercalation/de-intercalation behavior with specific capacitance reaching ca. 737 and 606 F g{sup -} {sup 1} at 25 and 500 mV s{sup -1} in 12 M LiCl between -0.2 and 0.8 V. In 14 M LiCl, retention of specific capacitance is about 95% when the scan rate is increased from 25 to 500 mV s{sup -} {sup 1}. This work is the first report showing the ultrahigh rate of Li-ion intercalation/de-intercalation in VO{sub x}.yH{sub 2}O. A so-called Li-ion supercapacitor of the asymmetric type consisting of a VO{sub x}.yH{sub 2}O cathode and a WO{sub 3}{sup .}zH{sub 2}O anode is proposed here. (author)
10. Asymmetric Distributions of Energetic Circulating Ions and Sawtooth Control using ICCD and Unbalanced NBI
International Nuclear Information System (INIS)
Graves, J. P.
2007-01-01
There is little doubt that various auxiliary heating systems are successfully and routinely controlling sawteeth. There is however some room for improving our understanding of the mechanisms that influence these important changes to the discharges. A mechanism that appears to be common across ECCS, ICCD and unbalanced NBI discharges involves the effect of the q = 1 localised current drive perturbation on resistive diffusion during the sawtooth ramp. Nevertheless, it is important to look for explanations for sawtooth control which may exist in ion based auxiliary systems, but may differ or not exist in electron auxiliary means of sawtooth control. The reason for this is that monster sawteeth, initially lengthened by trapped energetic ions, have up to the present day only been controlled using ICCD, while in ITER the primary method for sawtooth control could be ECCD. A mechanism based on the finite orbit width of parallel asymmetric energetic circulating particles is only non-negligible for ion based auxiliary systems. The present contribution examines the relevance of the latter in sawtooth control experiments, such as those using ICCD and NBI at JET, by looking carefully at the role of circulating ions close to the trapped boundary. At such pitch angles the orbit width is largest, and the parallel asymmetry of the distribution function has the greatest influence. (Author)
11. Nonlinear Waveforms for Ion-Acoustic Waves in Weakly Relativistic Plasma of Warm Ion-Fluid and Isothermal Electrons
Directory of Open Access Journals (Sweden)
S. A. El-Wakil
2012-01-01
Full Text Available The reductive perturbation method has been employed to derive the Korteweg-de Vries (KdV equation for small- but finite-amplitude electrostatic ion-acoustic waves in weakly relativistic plasma consisting of warm ions and isothermal electrons. An algebraic method with computerized symbolic computation is applied in obtaining a series of exact solutions of the KdV equation. Numerical studies have been made using plasma parameters which reveal different solutions, that is, bell-shaped solitary pulses, rational pulses, and solutions with singularity at finite points, which called “blowup” solutions in addition to the propagation of an explosive pulses. The weakly relativistic effect is found to significantly change the basic properties (namely, the amplitude and the width of the ion-acoustic waves. The result of the present investigation may be applicable to some plasma environments, such as ionosphere region.
12. The obtaining and properties of asymmetric ion transport membrane for separating of oxygen from air
Science.gov (United States)
Solovieva, A. A.; Kulbakin, I. V.
2018-04-01
The bilayer oxygen-permeable membrane, consisting of a thin-film dense composite based on Co3O4 - 36 wt. % Bi2O3, and of a porous ceramic substrate of Co2SiO4, was synthesized and characterized. The way for obtaining of porous ceramic based on cobalt silicate was found, while the microstructure and the mechanical properties of porous ceramic were studied. Layered casting with post-pressing was used to cover the surface of porous support of Co2SiO4 by the Co3O4 - 36 wt. % Bi2O3 - based film. Transport properties of the asymmetric membrane have been studied, the kinetic features of oxygen transport have been established, and the characteristic thickness of the membrane has been estimated. The methods to prevent the high-temperature creep of ion transport membranes based on solid/molten oxides, which are the promising ones for obtaining of pure oxygen from air, are proposed and discussed.
13. Capacitively coupled radio-frequency plasmas excited by tailored voltage waveforms
International Nuclear Information System (INIS)
Lafleur, T; Delattre, P A; Booth, J P; Johnson, E V
2013-01-01
By applying certain types of ‘tailored’ voltage waveforms (TVWs) to capacitively coupled plasmas, a dc self-bias and an asymmetric plasma response can be produced, even in geometrically symmetric reactors. Furthermore, these arbitrary applied waveforms can produce a number of interesting phenomena that are not present in typical single-frequency sinusoidal discharges. This electrical asymmetry effect presents emerging possibilities for the improved control of the ion energy and ion flux in these systems; parameters of vital importance to both etching and deposition applications for materials processing. With a combined research approach utilizing both experimental measurements, and particle-in-cell simulations, we review and extend recent investigations that study a particular class of TVW. The waveforms used have a pulse-type shape and are composed of a varying number of harmonic frequencies. This allows a strong self-bias to be produced, and causes most of the applied voltage to be dropped across a single sheath. Additionally, decreasing the pulse width (by increasing the number of harmonics), allows the plasma density and ion flux to be increased. Simulation and experimental results both demonstrate that this type of waveform can be used to separately control the ion flux and ion energy, while still producing a uniform plasma over large area (50 cm diameter) rf electrodes. (paper)
14. Asymmetric fission and evaporation of C60r+ (r = 2-4) fullerene ions in ion-C60 collisions: II. Dependence on collisional processes?
International Nuclear Information System (INIS)
Rentenier, A; Bordenave-Montesquieu, A; Moretto-Capelle, P; Bordenave-Montesquieu, D
2004-01-01
In this paper, a quantitative comparison of our experimental data for the asymmetrical fission (AF) and neutral evaporation of the C 60 molecule under proton impact (part I) is made with data published by other authors and often obtained in rather different collisional systems. The comparison with multicharged ions for which more quantitative data are available is focused on. It is demonstrated that size distributions of fragments, averaged fragment sizes, branching ratios between AF and evaporation or between AF channels, are common to all the collisional systems. Differences only appear when the comparison includes the undissociated stable fullerene ion signals
15. Power supply and impedance matching to drive technological radio-frequency plasmas with customized voltage waveforms.
Science.gov (United States)
Franek, James; Brandt, Steven; Berger, Birk; Liese, Martin; Barthel, Matthias; Schüngel, Edmund; Schulze, Julian
2015-05-01
We present a novel radio-frequency (RF) power supply and impedance matching to drive technological plasmas with customized voltage waveforms. It is based on a system of phase-locked RF generators that output single frequency voltage waveforms corresponding to multiple consecutive harmonics of a fundamental frequency. These signals are matched individually and combined to drive a RF plasma. Electrical filters are used to prevent parasitic interactions between the matching branches. By adjusting the harmonics' phases and voltage amplitudes individually, any voltage waveform can be approximated as a customized finite Fourier series. This RF supply system is easily adaptable to any technological plasma for industrial applications and allows the commercial utilization of process optimization based on voltage waveform tailoring for the first time. Here, this system is tested on a capacitive discharge based on three consecutive harmonics of 13.56 MHz. According to the Electrical Asymmetry Effect, tuning the phases between the applied harmonics results in an electrical control of the DC self-bias and the mean ion energy at almost constant ion flux. A comparison with the reference case of an electrically asymmetric dual-frequency discharge reveals that the control range of the mean ion energy can be significantly enlarged by using more than two consecutive harmonics.
16. Affine-response model of molecular solvation of ions: Accurate predictions of asymmetric charging free energies.
Science.gov (United States)
Bardhan, Jaydeep P; Jungwirth, Pavel; Makowski, Lee
2012-09-28
Two mechanisms have been proposed to drive asymmetric solvent response to a solute charge: a static potential contribution similar to the liquid-vapor potential, and a steric contribution associated with a water molecule's structure and charge distribution. In this work, we use free-energy perturbation molecular-dynamics calculations in explicit water to show that these mechanisms act in complementary regimes; the large static potential (∼44 kJ/mol/e) dominates asymmetric response for deeply buried charges, and the steric contribution dominates for charges near the solute-solvent interface. Therefore, both mechanisms must be included in order to fully account for asymmetric solvation in general. Our calculations suggest that the steric contribution leads to a remarkable deviation from the popular "linear response" model in which the reaction potential changes linearly as a function of charge. In fact, the potential varies in a piecewise-linear fashion, i.e., with different proportionality constants depending on the sign of the charge. This discrepancy is significant even when the charge is completely buried, and holds for solutes larger than single atoms. Together, these mechanisms suggest that implicit-solvent models can be improved using a combination of affine response (an offset due to the static potential) and piecewise-linear response (due to the steric contribution).
17. Affine-response model of molecular solvation of ions: Accurate predictions of asymmetric charging free energies
Science.gov (United States)
Bardhan, Jaydeep P.; Jungwirth, Pavel; Makowski, Lee
2012-01-01
Two mechanisms have been proposed to drive asymmetric solvent response to a solute charge: a static potential contribution similar to the liquid-vapor potential, and a steric contribution associated with a water molecule's structure and charge distribution. In this work, we use free-energy perturbation molecular-dynamics calculations in explicit water to show that these mechanisms act in complementary regimes; the large static potential (∼44 kJ/mol/e) dominates asymmetric response for deeply buried charges, and the steric contribution dominates for charges near the solute-solvent interface. Therefore, both mechanisms must be included in order to fully account for asymmetric solvation in general. Our calculations suggest that the steric contribution leads to a remarkable deviation from the popular “linear response” model in which the reaction potential changes linearly as a function of charge. In fact, the potential varies in a piecewise-linear fashion, i.e., with different proportionality constants depending on the sign of the charge. This discrepancy is significant even when the charge is completely buried, and holds for solutes larger than single atoms. Together, these mechanisms suggest that implicit-solvent models can be improved using a combination of affine response (an offset due to the static potential) and piecewise-linear response (due to the steric contribution). PMID:23020318
18. Electron Currents and Heating in the Ion Diffusion Region of Asymmetric Reconnection
Science.gov (United States)
Graham, D. B.; Khotyaintsev, Yu. V.; Norgren, C.; Vaivads, A.; Andre, M.; Lindqvist, P. A.; Marklund, G. T.; Ergun, R. E.; Paterson, W. R.; Gershman, D. J.;
2016-01-01
In this letter the structure of the ion diffusion region of magnetic reconnection at Earths magnetopause is investigated using the Magnetospheric Multiscale (MMS) spacecraft. The ion diffusion region is characterized by a strong DC electric field, approximately equal to the Hall electric field, intense currents, and electron heating parallel to the background magnetic field. Current structures well below ion spatial scales are resolved, and the electron motion associated with lower hybrid drift waves is shown to contribute significantly to the total current density. The electron heating is shown to be consistent with large-scale parallel electric fields trapping and accelerating electrons, rather than wave-particle interactions. These results show that sub-ion scale processes occur in the ion diffusion region and are important for understanding electron heating and acceleration.
19. Energy Technology Data Exchange (ETDEWEB)
Rentenier, A; Bordenave-Montesquieu, A; Moretto-Capelle, P; Bordenave-Montesquieu, D [LCAR-IRSAMC, UMR 5589 Universite Paul Sabatier-CNRS, 118 rte de Narbonne, 31062 Toulouse Cedex (France)
2004-06-28
A quantitative description of the asymmetric fission (AF) of C{sub 60}{sup r+} fullerene ions (r = 2-4), using a multistop coincidence technique between both fragment ions, is presented. Charged light fragment (LF) and heavy fragment (HF) size distributions are discussed together with the corresponding averaged sizes. Complete AF distributions are reported for the first time for C{sub 60}{sup 2+} ions. Simple dependences of the more probable channels and averaged fragment sizes on the partner size are found and discussed. The LF ones are not very sensitive to the parent fullerene ion charge r and vary linearly with the HF size at least for the largest ones. On the other hand the HF ones present an oscillating dependence against the LF size, the odd-numbered LFs being correlated to a smaller HF size, and depend on r. In the comparison of branching ratios between AF and the competing pure neutral evaporation channel, some emphasis is given to the behaviour of the unimolecular processes with r which are compared with the evolution of the activation energies and fission barriers. From a close examination of the individual HF distributions the production mechanisms of odd-n fragments are discussed, and the most probable dissociation channels of even-numbered C{sub n}{sup +} excited carbon clusters identified. Finally, an analysis of the neutral channels is also presented for the first time, the total neutral mass N (in carbon units) being deduced from the mass conservation law. Surprising similarities between the charged LF- and N-distributions are found. AF processes are also identified where light neutrals and ions play a symmetrical role. These findings lead us to suggest that a concerted emission of ions and heavy neutrals is probably a fission mechanism to be considered to understand the AF process of the C{sub 60} molecule in addition to the often assumed multistep fragmentation cascade scheme.
20. Asymmetric fission and evaporation of C60r+ (r = 2-4) fullerene ions in ion-C60 collisions: I. Proton results
International Nuclear Information System (INIS)
Rentenier, A; Bordenave-Montesquieu, A; Moretto-Capelle, P; Bordenave-Montesquieu, D
2004-01-01
A quantitative description of the asymmetric fission (AF) of C 60 r+ fullerene ions (r = 2-4), using a multistop coincidence technique between both fragment ions, is presented. Charged light fragment (LF) and heavy fragment (HF) size distributions are discussed together with the corresponding averaged sizes. Complete AF distributions are reported for the first time for C 60 2+ ions. Simple dependences of the more probable channels and averaged fragment sizes on the partner size are found and discussed. The LF ones are not very sensitive to the parent fullerene ion charge r and vary linearly with the HF size at least for the largest ones. On the other hand the HF ones present an oscillating dependence against the LF size, the odd-numbered LFs being correlated to a smaller HF size, and depend on r. In the comparison of branching ratios between AF and the competing pure neutral evaporation channel, some emphasis is given to the behaviour of the unimolecular processes with r which are compared with the evolution of the activation energies and fission barriers. From a close examination of the individual HF distributions the production mechanisms of odd-n fragments are discussed, and the most probable dissociation channels of even-numbered C n + excited carbon clusters identified. Finally, an analysis of the neutral channels is also presented for the first time, the total neutral mass N (in carbon units) being deduced from the mass conservation law. Surprising similarities between the charged LF- and N-distributions are found. AF processes are also identified where light neutrals and ions play a symmetrical role. These findings lead us to suggest that a concerted emission of ions and heavy neutrals is probably a fission mechanism to be considered to understand the AF process of the C 60 molecule in addition to the often assumed multistep fragmentation cascade scheme
1. Harmonic arbitrary waveform generator
Science.gov (United States)
Roberts, Brock Franklin
2017-11-28
High frequency arbitrary waveforms have applications in radar, communications, medical imaging, therapy, electronic warfare, and charged particle acceleration and control. State of the art arbitrary waveform generators are limited in the frequency they can operate by the speed of the Digital to Analog converters that directly create their arbitrary waveforms. The architecture of the Harmonic Arbitrary Waveform Generator allows the phase and amplitude of the high frequency content of waveforms to be controlled without taxing the Digital to Analog converters that control them. The Harmonic Arbitrary Waveform Generator converts a high frequency input, into a precision, adjustable, high frequency arbitrary waveform.
2. Asymmetric fission and evaporation of Cr+60 (r = 2-4) fullerene ions in ion-C60 collisions: III. Universal behaviour of fission
International Nuclear Information System (INIS)
Bordenave-Montesquieu, D; Bordenave-Montesquieu, A; Rentenier, A; Moretto-Capelle, P
2005-01-01
The behaviour of the asymmetrical fission (AF) scheme (correlated ion distributions) against the collision conditions is investigated using H + x (x = 1-3) and He + projectiles in the 1-130 keV collision energy range. The present work is an extension of our recent publications on this topic using 11 keV protons (Rentenier et al 2004 J. Phys. B: At. Mol. Opt. Phys. 37 2429 and 2455). The threshold for AF is observed at 2 keV proton energy corresponding to a maximum deposited energy equal to about 41 eV. The main result concerns the fragment distributions resulting from AF of C r+ 60 ions, and secondary dissociation of even-n C + n fragments, which are both found to remain independent of the projectile species and collision velocity. These findings indicate that they are insensitive to the internal energy distributions of the parent ions. In addition, a contribution of binary collisions between the projectile and individual carbon atoms of the C 60 molecule to AF is identified in the C + 1 production at the lowest collision velocities, the so-called impulsive fragmentation
3. Affine-response model of molecular solvation of ions: Accurate predictions of asymmetric charging free energies
Czech Academy of Sciences Publication Activity Database
Bardhan, J. P.; Jungwirth, Pavel; Makowski, L.
Roč. 137, č. 12 ( 2012 ), 124101/1-124101/6 ISSN 0021-9606 R&D Projects: GA MŠk LH12001 Institutional research plan: CEZ:AV0Z40550506 Keywords : ion solvation * continuum models * linear response Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.164, year: 2012
4. A 2D ion chamber array audit of wedged and asymmetric fields in an inhomogeneous lung phantom
Energy Technology Data Exchange (ETDEWEB)
Lye, Jessica; Dunn, Leon, E-mail: [email protected]; Alves, Andrew [Australian Clinical Dosimetry Service, Yallambie, Victoria 3085 (Australia); Kenny, John [Australian Clinical Dosimetry Service, Yallambie, Victoria 3085, Australia and Radiation Oncology Queensland, Toowoomba, Queensland 4350 (Australia); Lehmann, Joerg; Williams, Ivan [Australian Clinical Dosimetry Service, Yallambie, Victoria 3085, Australia and School of Applied Science, RMIT University, Melbourne 3000 (Australia); Kron, Tomas [School of Applied Science, RMIT University, Melbourne 3000, Australia and Peter MacCallum Cancer Centre, Melbourne 3008 (Australia); Cole, Andrew [Australian Clinical Dosimetry Service, Yallambie, Victoria 3085, Australia and Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Victoria 3085 (Australia)
2014-10-15
Purpose: The Australian Clinical Dosimetry Service (ACDS) has implemented a new method of a nonreference condition Level II type dosimetric audit of radiotherapy services to increase measurement accuracy and patient safety within Australia. The aim of this work is to describe the methodology, tolerances, and outcomes from the new audit. Methods: The ACDS Level II audit measures the dose delivered in 2D planes using an ionization chamber based array positioned at multiple depths. Measurements are made in rectilinear homogeneous and inhomogeneous phantoms composed of slabs of solid water and lung. Computer generated computed tomography data sets of the rectilinear phantoms are supplied to the facility prior to audit for planning of a range of cases including reference fields, asymmetric fields, and wedged fields. The audit assesses 3D planning with 6 MV photons with a static (zero degree) gantry. Scoring is performed using local dose differences between the planned and measured dose within 80% of the field width. The overall audit result is determined by the maximum dose difference over all scoring points, cases, and planes. Pass (Optimal Level) is defined as maximum dose difference ≤3.3%, Pass (Action Level) is ≤5.0%, and Fail (Out of Tolerance) is >5.0%. Results: At close of 2013, the ACDS had performed 24 Level II audits. 63% of the audits passed, 33% failed, and the remaining audit was not assessable. Of the 15 audits that passed, 3 were at Pass (Action Level). The high fail rate is largely due to a systemic issue with modeling asymmetric 60° wedges which caused a delivered overdose of 5%–8%. Conclusions: The ACDS has implemented a nonreference condition Level II type audit, based on ion chamber 2D array measurements in an inhomogeneous slab phantom. The powerful diagnostic ability of this audit has allowed the ACDS to rigorously test the treatment planning systems implemented in Australian radiotherapy facilities. Recommendations from audits have led to
5. A 2D ion chamber array audit of wedged and asymmetric fields in an inhomogeneous lung phantom
International Nuclear Information System (INIS)
Lye, Jessica; Dunn, Leon; Alves, Andrew; Kenny, John; Lehmann, Joerg; Williams, Ivan; Kron, Tomas; Cole, Andrew
2014-01-01
Purpose: The Australian Clinical Dosimetry Service (ACDS) has implemented a new method of a nonreference condition Level II type dosimetric audit of radiotherapy services to increase measurement accuracy and patient safety within Australia. The aim of this work is to describe the methodology, tolerances, and outcomes from the new audit. Methods: The ACDS Level II audit measures the dose delivered in 2D planes using an ionization chamber based array positioned at multiple depths. Measurements are made in rectilinear homogeneous and inhomogeneous phantoms composed of slabs of solid water and lung. Computer generated computed tomography data sets of the rectilinear phantoms are supplied to the facility prior to audit for planning of a range of cases including reference fields, asymmetric fields, and wedged fields. The audit assesses 3D planning with 6 MV photons with a static (zero degree) gantry. Scoring is performed using local dose differences between the planned and measured dose within 80% of the field width. The overall audit result is determined by the maximum dose difference over all scoring points, cases, and planes. Pass (Optimal Level) is defined as maximum dose difference ≤3.3%, Pass (Action Level) is ≤5.0%, and Fail (Out of Tolerance) is >5.0%. Results: At close of 2013, the ACDS had performed 24 Level II audits. 63% of the audits passed, 33% failed, and the remaining audit was not assessable. Of the 15 audits that passed, 3 were at Pass (Action Level). The high fail rate is largely due to a systemic issue with modeling asymmetric 60° wedges which caused a delivered overdose of 5%–8%. Conclusions: The ACDS has implemented a nonreference condition Level II type audit, based on ion chamber 2D array measurements in an inhomogeneous slab phantom. The powerful diagnostic ability of this audit has allowed the ACDS to rigorously test the treatment planning systems implemented in Australian radiotherapy facilities. Recommendations from audits have led to
6. Primary amine/CSA ion pair: A powerful catalytic system for the asymmetric enamine catalysis
KAUST Repository
Liu, Chen; Zhu, Qiang; Huang, Kuo-Wei; Lu, Yixin
2011-01-01
A novel ion pair catalyst containing a chiral counteranion can be readily derived by simply mixing cinchona alkaloid-derived diamine with chiral camphorsulfonic acid (CSA). A mixture of 9-amino(9-deoxy)epi-quinine 8 and (-)-CSA was found to be the best catalyst with matching chirality, enabling the direct amination of α-branched aldehydes to proceed in quantitative yields and with nearly perfect enantioselectivities. A 0.5 mol % catalyst loading was sufficient to catalyze the reaction, and a gram scale enantioselective synthesis of biologically important α-methyl phenylglycine has been successfully demonstrated. © 2011 American Chemical Society.
7. Primary amine/CSA ion pair: A powerful catalytic system for the asymmetric enamine catalysis
KAUST Repository
Liu, Chen
2011-05-20
A novel ion pair catalyst containing a chiral counteranion can be readily derived by simply mixing cinchona alkaloid-derived diamine with chiral camphorsulfonic acid (CSA). A mixture of 9-amino(9-deoxy)epi-quinine 8 and (-)-CSA was found to be the best catalyst with matching chirality, enabling the direct amination of α-branched aldehydes to proceed in quantitative yields and with nearly perfect enantioselectivities. A 0.5 mol % catalyst loading was sufficient to catalyze the reaction, and a gram scale enantioselective synthesis of biologically important α-methyl phenylglycine has been successfully demonstrated. © 2011 American Chemical Society.
8. Programmable waveform controller
International Nuclear Information System (INIS)
Yeh, H.T.
1979-01-01
A programmable waveform controller (PWC) was developed for voltage waveform generation in the laboratory. It is based on the Intel 8080 family of chips. The hardware uses the modular board approach, sharing a common 44-pin bus. The software contains two separate programs: the first generates a single connected linear ramp waveform and is capable of bipolar operation, linear interpolation between input data points, extended time range, and cycling; the second generates four independent square waveforms with variable duration and amplitude
9. Detection of Potato Storage Disease via Gas Analysis: A Pilot Study Using Field Asymmetric Ion Mobility Spectrometry
Directory of Open Access Journals (Sweden)
Massimo Rutolo
2014-08-01
Full Text Available Soft rot is a commonly occurring potato tuber disease that each year causes substantial losses to the food industry. Here, we explore the possibility of early detection of the disease via gas/vapor analysis, in a laboratory environment, using a recent technology known as FAIMS (Field Asymmetric Ion Mobility Spectrometry. In this work, tubers were inoculated with a bacterium causing the infection, Pectobacterium carotovorum, and stored within set environmental conditions in order to manage disease progression. They were compared with controls stored in the same conditions. Three different inoculation time courses were employed in order to obtain diseased potatoes showing clear signs of advanced infection (for standard detection and diseased potatoes with no apparent evidence of infection (for early detection. A total of 156 samples were processed by PCA (Principal Component Analysis and k-means clustering. Results show a clear discrimination between controls and diseased potatoes for all experiments with no difference among observations from standard and early detection. Further analysis was carried out by means of a statistical model based on LDA (Linear Discriminant Analysis that showed a high classification accuracy of 92.1% on the test set, obtained via a LOOCV (leave-one out cross-validation.
10. Catalytic asymmetric dihydroxylation of olefins with reusable OsO(4)(2-) on ion-exchangers: the scope and reactivity using various cooxidants.
Science.gov (United States)
Choudary, Boyapati M; Chowdari, Naidu S; Jyothi, Karangula; Kantam, Mannepalli L
2002-05-15
Exchanger-OsO(4) catalysts are prepared by an ion-exchange technique using layered double hydroxides and quaternary ammonium salts covalently bound to resin and silica as ion-exchangers. The ion-exchangers with different characteristics and opposite ion selectivities are specially chosen to produce the best heterogeneous catalyst that can operate using the various cooxidants in the asymmetric dihydroxylation reaction. LDH-OsO(4) catalysts composed of different compositions are evaluated for the asymmetric dihydroxylation of trans-stilbene. Resin-OsO(4) and SiO(2)-OsO(4) designed to overcome the problems associated with LDH-OsO(4) indeed show consistent activity and enantioselectivity in asymmetric dihydroxylation of olefins using K(3)Fe(CN)(6) and molecular oxygen as cooxidants. Compared to the Kobayashi heterogeneous systems, resin-OsO(4) is a very efficient catalyst for the dihydroxylation of a wide variety of aromatic, aliphatic, acyclic, cyclic, mono-, di-, and trisubstituted olefins to afford chiral vicinal diols with high yields and enantioselectivities irrespective of the cooxidant used. Resin-OsO(4) is recovered quantitatively by a simple filtration and reused for a number of cycles with consistent activity. The high binding ability of the heterogeneous osmium catalyst enables the use of an equimolar ratio of ligand to osmium to give excellent enantioselectives in asymmetric dihydroxylation in contrast to the homogeneous osmium system in which excess molar quantities of the expensive chiral ligand to osmium are invariably used. The complexation of the chiral ligand (DHQD)(2)PHAL, having very large dimension, a prerequisite to obtain higher ee, is possible only with the OsO(4)(2-) located on the surface of the supports.
11. Asymmetric hydration structure around calcium ion restricted in micropores fabricated in activated carbons
International Nuclear Information System (INIS)
Ohkubo, Takahiro; Kusudo, Tomoko; Kuroda, Yasushige
2016-01-01
The adsorbed phase and hydration structure of an aqueous solution of Ca(NO 3 ) 2 restricted in micropores fabricated in activated carbons (ACs) having different average pore widths (0.63 and 1.1 nm) were investigated with the analysis of adsorption isotherms and x-ray absorption fine structure (XAFS) spectra on Ca K -edge. The adsorbed density of Ca 2+ per unit micropore volume in the narrower pore was higher than in the wider pore, while the adsorbed amount per unit mass of carbon with the narrower pore was half of the amount of ACs with the larger pore. On the other hand, variations in the bands assigned to double-electron ( KM I ) and 1s → 3d excitations in XAFS spectra demonstrate the formation of a distorted hydration cluster around Ca 2+ in the micropore, although the structural parameters of hydrated Ca 2+ in the micropores were almost consistent with the bulk aqueous solution, as revealed by the analysis of extended XAFS (EXAFS) spectra. In contrast to the hydration structure of monovalent ions such as Rb + , which generally presents a dehydrated structure in smaller than 1 nm micropores in ACs, the present study clearly explains that the non-spherically-symmetric structure of hydrated Ca 2+ restricted in carbon micropores whose sizes are around 1 nm is experimentally revealed where any dehydration phenomena from the first hydration shell around Ca 2+ could not be observed. (paper)
12. Impact of flows on ion temperatures inferred from neutron spectra in asymmetrically driven OMEGA DT implosions
Science.gov (United States)
Gatu Johnson, M.; Frenje, J.; Lahmann, B.; Seguin, F.; Petrasso, R.; Appelbe, B.; Chittenden, J.; Walsh, C.; Delettrez, J.; Igumenshchev, I.; Knauer, J. P.; Glebov, V. Yu.; Forrest, C.; Grimble, W.; Marshall, F.; Michel, T.; Stoeckl, C.; Haines, B. M.; Zylstra, A. B.
2017-10-01
Ion temperatures (Tion) in Inertial Confinement Fusion (ICF) experiments have traditionally been inferred from the broadening of primary neutron spectra. Directional motion (flow) of the fuel at burn, expected to arise due to asymmetries imposed by e.g. engineering features or drive non-uniformity, also impacts broadening and may lead to artificially inflated Tion'' values. Flow due to low-mode asymmetries is expected to give rise to line-of-sight variations in measured Tion, as observed in OMEGA cryogenic DT implosions but not in similar experiments at the NIF. In this presentation, we report on OMEGA experiments with intentional drive asymmetry designed for testing the ability to accurately predict and measure line-of-sight differences in apparent Tion due to low-mode asymmetry-seeded flows. The measurements are contrasted to CHIMERA, RAGE and ASTER simulations, providing insight into implosion dynamics and the relative importance of laser drive non-uniformity, stalk and offset as sources of asymmetry. The results highlight the complexity of hot-spot dynamics, which is a problem that must be mastered to achieve ICF ignition. This work was supported in part by the U.S. DOE, NLUF and LLE.
13. A concentration-independent micro/nanofluidic active diode using an asymmetric ion concentration polarization layer.
Science.gov (United States)
Lee, Hyekyung; Kim, Junsuk; Kim, Hyeonsoo; Kim, Ho-Young; Lee, Hyomin; Kim, Sung Jae
2017-08-24
Over the past decade, nanofluidic diodes that rectify ionic currents (i.e. greater current in one direction than in the opposite direction) have drawn significant attention in biomolecular sensing, switching and energy harvesting devices. To obtain current rectification, conventional nanofluidic diodes have utilized complex nanoscale asymmetry such as nanochannel geometry, surface charge density, and reservoir concentration. Avoiding the use of sophisticated nano-asymmetry, micro/nanofluidic diodes using microscale asymmetry have been recently introduced; however, their diodic performance is still impeded by (i) low (even absent) rectification effects at physiological concentrations over 100 mM and strong dependency on the bulk concentration, and (ii) the fact that they possess only passive predefined rectification factors. Here, we demonstrated a new class of micro/nanofluidic diode with an ideal perm-selective nanoporous membrane based on ion concentration polarization (ICP) phenomenon. Thin side-microchannels installed near a nanojunction served as mitigators of the amplified electrokinetic flows generated by ICP and induced convective salt transfer to the nanoporous membrane, leading to actively controlled micro-scale asymmetry. Using this device, current rectifications were successfully demonstrated in a wide range of electrolytic concentrations (10 -5 M to 3 M) as a function of the fluidic resistance of the side-microchannels. Noteworthily, it was confirmed that the rectification factors were independent from the bulk concentration due to the ideal perm-selectivity. Moreover, the rectification of the presenting diode was actively controlled by adjusting the external convective flows, while that of the previous diode was passively determined by invariant nanoscale asymmetry.
14. Dressed ion theory of size-asymmetric electrolytes: effective ionic charges and the decay length of screened Coulomb potential and pair correlations.
Science.gov (United States)
Forsberg, Björn; Ulander, Johan; Kjellander, Roland
2005-02-08
The effects of ionic size asymmetry on long-range electrostatic interactions in electrolyte solutions are investigated within the primitive model. Using the formalism of dressed ion theory we analyze correlation functions from Monte Carlo simulations and the hypernetted chain approximation for size asymmetric 1:1 electrolytes. We obtain decay lengths of the screened Coulomb potential, effective charges of ions, and effective permittivity of the solution. It is found that the variation of these quantities with the degree of size asymmetry depends in a quite intricate manner on the interplay between the electrostatic coupling and excluded volume effects. In most cases the magnitude of the effective charge of the small ion species is larger than that of the large species; the difference increases with increasing size asymmetry. The effective charges of both species are larger (in absolute value) than the bare ionic charge, except for high asymmetry where the effective charge of the large ions can become smaller than the bare charge.
15. HCN4 ion channel function is required for early events that regulate anatomical left-right patterning in a nodal and lefty asymmetric gene expression-independent manner.
Science.gov (United States)
Pai, Vaibhav P; Willocq, Valerie; Pitcairn, Emily J; Lemire, Joan M; Paré, Jean-François; Shi, Nian-Qing; McLaughlin, Kelly A; Levin, Michael
2017-10-15
Laterality is a basic characteristic of all life forms, from single cell organisms to complex plants and animals. For many metazoans, consistent left-right asymmetric patterning is essential for the correct anatomy of internal organs, such as the heart, gut, and brain; disruption of left-right asymmetry patterning leads to an important class of birth defects in human patients. Laterality functions across multiple scales, where early embryonic, subcellular and chiral cytoskeletal events are coupled with asymmetric amplification mechanisms and gene regulatory networks leading to asymmetric physical forces that ultimately result in distinct left and right anatomical organ patterning. Recent studies have suggested the existence of multiple parallel pathways regulating organ asymmetry. Here, we show that an isoform of the hyperpolarization-activated cyclic nucleotide-gated (HCN) family of ion channels (hyperpolarization-activated cyclic nucleotide-gated channel 4, HCN4) is important for correct left-right patterning. HCN4 channels are present very early in Xenopus embryos. Blocking HCN channels ( I h currents) with pharmacological inhibitors leads to errors in organ situs. This effect is only seen when HCN4 channels are blocked early (pre-stage 10) and not by a later block (post-stage 10). Injections of HCN4-DN (dominant-negative) mRNA induce left-right defects only when injected in both blastomeres no later than the 2-cell stage. Analysis of key asymmetric genes' expression showed that the sidedness of Nodal , Lefty , and Pitx2 expression is largely unchanged by HCN4 blockade, despite the randomization of subsequent organ situs, although the area of Pitx2 expression was significantly reduced. Together these data identify a novel, developmental role for HCN4 channels and reveal a new Nodal-Lefty-Pitx2 asymmetric gene expression-independent mechanism upstream of organ positioning during embryonic left-right patterning. © 2017. Published by The Company of Biologists Ltd.
16. Asymmetric fission and evaporation of C{sub 60}{sup r+} (r = 2-4) fullerene ions in ion-C{sub 60} collisions: II. Dependence on collisional processes?
Energy Technology Data Exchange (ETDEWEB)
Rentenier, A; Bordenave-Montesquieu, A; Moretto-Capelle, P; Bordenave-Montesquieu, D [LCAR-IRSAMC, UMR 5589 Universite Paul Sabatier-CNRS, 118 rte de Narbonne, 31062 Toulouse Cedex (France)
2004-06-28
In this paper, a quantitative comparison of our experimental data for the asymmetrical fission (AF) and neutral evaporation of the C{sub 60} molecule under proton impact (part I) is made with data published by other authors and often obtained in rather different collisional systems. The comparison with multicharged ions for which more quantitative data are available is focused on. It is demonstrated that size distributions of fragments, averaged fragment sizes, branching ratios between AF and evaporation or between AF channels, are common to all the collisional systems. Differences only appear when the comparison includes the undissociated stable fullerene ion signals.
17. Near-surface density profiling of Fe ion irradiated Si (100) using extremely asymmetric x-ray diffraction by variation of the wavelength
Energy Technology Data Exchange (ETDEWEB)
Khanbabaee, B., E-mail: [email protected]; Pietsch, U. [Solid State Physics, University of Siegen, D-57068 Siegen (Germany); Facsko, S. [Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden (Germany); Doyle, S. [Synchrotron Light Source ANKA, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)
2014-10-20
In this work, we report on correlations between surface density variations and ion parameters during ion beam-induced surface patterning process. The near-surface density variations of irradiated Si(100) surfaces were investigated after off-normal irradiation with 5 keV Fe ions at different fluences. In order to reduce the x-ray probing depth to a thickness below 5 nm, the extremely asymmetrical x-ray diffraction by variation of wavelength was applied, exploiting x-ray refraction at the air-sample interface. Depth profiling was achieved by measuring x-ray rocking curves as function of varying wavelengths providing incidence angles down to 0°. The density variation was extracted from the deviations from kinematical Bragg angle at grazing incidence angles due to refraction of the x-ray beam at the air-sample interface. The simulations based on the dynamical theory of x-ray diffraction revealed that while a net near-surface density decreases with increasing ion fluence which is accompanied by surface patterning, there is a certain threshold of ion fluence to surface density modulation. Our finding suggests that the surface density variation can be relevant with the mechanism of pattern formation.
18. Surrogate waveform models
Science.gov (United States)
Blackman, Jonathan; Field, Scott; Galley, Chad; Scheel, Mark; Szilagyi, Bela; Tiglio, Manuel
2015-04-01
With the advanced detector era just around the corner, there is a strong need for fast and accurate models of gravitational waveforms from compact binary coalescence. Fast surrogate models can be built out of an accurate but slow waveform model with minimal to no loss in accuracy, but may require a large number of evaluations of the underlying model. This may be prohibitively expensive if the underlying is extremely slow, for example if we wish to build a surrogate for numerical relativity. We examine alternate choices to building surrogate models which allow for a more sparse set of input waveforms. Research supported in part by NSERC.
19. Strain evolution in Si substrate due to implantation of MeV ion observed by extremely asymmetric x-ray diffraction
International Nuclear Information System (INIS)
Emoto, T.; Ghatak, J.; Satyam, P. V.; Akimoto, K.
2009-01-01
We studied the strain introduced in a Si(111) substrate due to MeV ion implantation using extremely asymmetric x-ray diffraction and measured the rocking curves of asymmetrical 113 diffraction for the Si substrates implanted with a 1.5 MeV Au 2+ ion at fluence values of 1x10 13 , 5x10 13 , and 1x10 14 /cm 2 . The measured curves consisted of a bulk peak and accompanying subpeak with an interference fringe. The positional relationship of the bulk peak to the subpeak and the intensity variation of those peaks with respect to the wavelengths of the x rays indicated that crystal lattices near the surface were strained; the lattice spacing of surface normal (111) planes near the surface was larger than that of the bulk. Detailed strain profiles along the depth direction were successfully estimated using a curve-fitting method based on Darwin's dynamical diffraction theory. Comparing the shapes of resultant strain profiles, we found that a strain evolution rapidly occurred within a depth of ∼300 nm at fluence values between 1x10 13 and 5x10 13 /cm 2 . This indicates that formation of the complex defects progressed near the surface when the fluence value went beyond a critical value between 1x10 13 and 5x10 13 /cm 2 and the defects brought a large strain to the substrate.
20. Electrical Double-Layer and Ion Bridging Forces between Symmetric and Asymmetric Charged Surfaces in the Presence of Mono- and Divalent Ions
DEFF Research Database (Denmark)
Liu, Xiaoyan; Feilberg, Karen Louise; Yan, Wei
2017-01-01
charged (3-aminopropyl)trimethoxysilane, and the negatively charged (3-mercaptopropyl)trimethoxysilane. The interactions between the three symmetric systems, as well as between the three asymmetric combinations of surfaces, were measured and compared to calculated electrical double-layer forces...
1. Compressive full waveform lidar
Science.gov (United States)
Yang, Weiyi; Ke, Jun
2017-05-01
To avoid high bandwidth detector, fast speed A/D converter, and large size memory disk, a compressive full waveform LIDAR system, which uses a temporally modulated laser instead of a pulsed laser, is studied in this paper. Full waveform data from NEON (National Ecological Observatory Network) are used. Random binary patterns are used to modulate the source. To achieve 0.15 m ranging resolution, a 100 MSPS A/D converter is assumed to make measurements. SPIRAL algorithm with canonical basis is employed when Poisson noise is considered in the low illuminated condition.
2. Determination of biogenic amines in chocolate by ion chromatographic separation and pulsed integrated amperometric detection with implemented wave-form at Au disposable electrode.
Science.gov (United States)
Pastore, Paolo; Favaro, Gabriella; Badocco, Denis; Tapparo, Andrea; Cavalli, Silvano; Saccani, Giovanna
2005-12-09
A rapid and selective cation exchange chromatographic method coupled to integrated pulsed amperometric detection (PAD) has been developed to quantify biogenic amines in chocolate. The method is based on gradient elution of aqueous methanesulfonic acid with post column addition of strong base to obtain suitable conditions for amperometric detection. A potential waveform able to keep long time performance of the Au disposable electrode was set up. Total analysis time is less than 20min. Concentration levels of dopamine, serotonin, tyramine, histamine and 2-phenylethylamine were measured, after extraction with perchloric acid from 2g samples previously defatted twice with petroleum ether. The method was used to determine the analytes in chocolate real matrices and their quantification was made with standard addition method. Only dopamine, histamine and serotonin were found in the analysed real samples. Repeatabilities of their signals, computed on their amounts in the real samples, were 5% for all of them. Repeatabilities of tyramine and phenethylamine were relative to standard additions to real samples (close to 1mg/l in the extract) and were 7 and 3%, respectively. Detection limits were computed with the 3s of the baseline noise combined with the calibration plot regression parameters. They were satisfactorily low for all amines: 3mg/kg for dopamine, 2mg/kg for tyramine, 1mg/kg for histamine, 2mg/kg for serotonin, 3mg/kg for 2-phenylethylamine.
3. Kinetic energies of charged fragments resulting from multifragmentation and asymmetric fission of the C60 molecule in collisions with monocharged ions (2-130 keV)
International Nuclear Information System (INIS)
Rentenier, A; Bordenave-Montesquieu, D; Moretto-Capelle, P; Bordenave-Montesquieu, A
2003-01-01
Multifragmentation and asymmetric fission (AF) of the C 60 molecule induced by H + , H 2 + , H 3 + and He + ions at medium collision energies (2-130 keV) are considered. Momenta and kinetic energies of C n + fragment ions (n = 1- 12) are deduced from an analysis of time-of-flight spectra. In multifragmentation processes, momenta are found to be approximately constant when n > 2, a behaviour which explains that the most probable kinetic energy, as well as the width of the kinetic energy distributions, is found to be inversely proportional to the fragment size n; both momenta and kinetic energies are independent of the velocity and nature of the projectile, and hence of the energy deposit. A specific study of the AF shows that the kinetic energies of C 2 + , C 4 + and C 6 + fragments are also independent of the collision velocity and projectile species; a quantitative agreement is found with values deduced from kinetic energy release measurements by another group in electron impact experiments, and the observed decrease when the mass of the light fragment increases is also reproduced. A quantitative comparison of AF and multifragmentation for the n = 2, 4 and 6 fragment ions shows that kinetic energies in AF exceed that in multifragmentation, a result which explains the oscillations observed when momenta or kinetic energies of fragments are plotted against the n-value. The AF yield is also found to scale with the energy deposit in the collision velocity range extending below the velocity at the maximum of the electronic stopping power; except for protons, it remains negligible with respect to multifragmentation as soon as the total energy deposit exceeds about 100 eV
4. Multichannel waveform display system
International Nuclear Information System (INIS)
Kolvankar, V.G.
1989-01-01
For any multichannel data acquisition system, a multichannel paper chart recorder undoubtedly forms an essential part of the system. When deployed on-line, it instantaneously provides, for visual inspection, hard copies of the signal waveforms on common time base at any desired sensitivity and time resolution. Within the country, only a small range of these strip chart recorder s is available, and under stringent specifications imported recorders are often procured. The cost of such recorders may range from 1 to 5 lakhs of rupees in foreign exchange. A system to provide on the oscilloscope a steady display of multichannel waveforms, refreshed from the digital data stored in the memory is developed. The merits and demerits of the display system are compared with that built around a conventional paper chart recorder. Various illustrations of multichannel seismic event data acquired at Gauribidanur seismic array station are also presented. (author). 2 figs
5. Molecular model of a cell plasma membrane with an asymmetric multicomponent composition: Water permeation and ion effects
Czech Academy of Sciences Publication Activity Database
Vácha, Robert; Berkowitz, M. L.; Jungwirth, Pavel
2009-01-01
Roč. 96, č. 11 (2009), s. 4493-4501 ISSN 0006-3495 R&D Projects: GA ČR(CZ) GD203/05/H001; GA ČR GA203/08/0114 Grant - others:NSF(US) MCB-0615469 Institutional research plan: CEZ:AV0Z40550506 Keywords : membrane * ions * molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.390, year: 2009
6. Asymmetric fission and evaporation of C{sup r+}{sub 60} (r = 2-4) fullerene ions in ion-C{sub 60} collisions: III. Universal behaviour of fission
Energy Technology Data Exchange (ETDEWEB)
Bordenave-Montesquieu, D; Bordenave-Montesquieu, A; Rentenier, A; Moretto-Capelle, P [LCAR-IRSAMC, UMR 5589 Universite Paul Sabatier-CNRS, 118 rte de Narbonne, 31062 Toulouse Cedex (France)
2005-04-14
The behaviour of the asymmetrical fission (AF) scheme (correlated ion distributions) against the collision conditions is investigated using H{sup +}{sub x} (x = 1-3) and He{sup +} projectiles in the 1-130 keV collision energy range. The present work is an extension of our recent publications on this topic using 11 keV protons (Rentenier et al 2004 J. Phys. B: At. Mol. Opt. Phys. 37 2429 and 2455). The threshold for AF is observed at 2 keV proton energy corresponding to a maximum deposited energy equal to about 41 eV. The main result concerns the fragment distributions resulting from AF of C{sup r+}{sub 60} ions, and secondary dissociation of even-n C{sup +}{sub n} fragments, which are both found to remain independent of the projectile species and collision velocity. These findings indicate that they are insensitive to the internal energy distributions of the parent ions. In addition, a contribution of binary collisions between the projectile and individual carbon atoms of the C{sub 60} molecule to AF is identified in the C{sup +}{sub 1} production at the lowest collision velocities, the so-called impulsive fragmentation.
7. Test results of distributed ion pump designs for the PEP-II Asymmetric B-Factory collider
Energy Technology Data Exchange (ETDEWEB)
Calderon, M.; Holdener, F.; Peterson, D. [Lawrence Livermore National Lab., CA (United States)] [and others
1994-07-01
The testing facility measurement methods and results of prototype distributed ion pump (DIP) designs for the PEP-II B-Factory High Energy Ring are presented. Two basic designs with 5- or 7-anode plates were tested at LLNL with penning cell sizes of 15, 18, and 21 mm. Direct comparison of 5- and 7-plate anodes with 18 mm holes shows increased pumping speed with the 7-plate design. The 5-plate, 18 mm and 7-plate, 15 mm designs both gave an average pumping speed of 135 1/s/m at 1 {times} 10{sup {minus}8} Torr nitrogen base pressure in a varying 0.18 T peak B-field. Comparison of the three hole sizes indicates that cells smaller than the 15 mm tested can be efficiently used to obtain higher pumping speeds for the same anode plate sizes used.
8. Test results of distributed ion pump designs for the PEP-II Asymmetric B-Factory collider
International Nuclear Information System (INIS)
Calderon, M.; Holdener, F.; Peterson, D.
1994-07-01
The testing facility measurement methods and results of prototype distributed ion pump (DIP) designs for the PEP-II B-Factory High Energy Ring are presented. Two basic designs with 5- or 7-anode plates were tested at LLNL with penning cell sizes of 15, 18, and 21 mm. Direct comparison of 5- and 7-plate anodes with 18 mm holes shows increased pumping speed with the 7-plate design. The 5-plate, 18 mm and 7-plate, 15 mm designs both gave an average pumping speed of 135 1/s/m at 1 x 10 -8 Torr nitrogen base pressure in a varying 0.18 T peak B-field. Comparison of the three hole sizes indicates that cells smaller than the 15 mm tested can be efficiently used to obtain higher pumping speeds for the same anode plate sizes used
9. Electronics via waveform analysis
CERN Document Server
Craig, Edwin C
1993-01-01
The author believes that a good basic understanding of electronics can be achieved by detailed visual analyses of the actual voltage waveforms present in selected circuits. The voltage waveforms included in this text were photographed using a 35-rrun camera in an attempt to make the book more attractive. This book is intended for the use of students with a variety of backgrounds. For this reason considerable material has been placed in the Appendix for those students who find it useful. The Appendix includes many basic electricity and electronic concepts as well as mathematical derivations that are not vital to the understanding of the circuit being discussed in the text at that time. Also some derivations might be so long that, if included in the text, it could affect the concentration of the student on the circuit being studied. The author has tried to make the book comprehensive enough so that a student could use it as a self-study course, providing one has access to adequate laboratory equipment.
10. Waveform analysis of sound
CERN Document Server
Tohyama, Mikio
2015-01-01
What is this sound? What does that sound indicate? These are two questions frequently heard in daily conversation. Sound results from the vibrations of elastic media and in daily life provides informative signals of events happening in the surrounding environment. In interpreting auditory sensations, the human ear seems particularly good at extracting the signal signatures from sound waves. Although exploring auditory processing schemes may be beyond our capabilities, source signature analysis is a very attractive area in which signal-processing schemes can be developed using mathematical expressions. This book is inspired by such processing schemes and is oriented to signature analysis of waveforms. Most of the examples in the book are taken from data of sound and vibrations; however, the methods and theories are mostly formulated using mathematical expressions rather than by acoustical interpretation. This book might therefore be attractive and informative for scientists, engineers, researchers, and graduat...
11. Waveform Sampler CAMAC Module
International Nuclear Information System (INIS)
Freytag, D.R.; Haller, G.M.; Kang, H.; Wang, J.
1985-09-01
A Waveform Sampler Module (WSM) for the measurement of signal shapes coming from the multi-hit drift chambers of the SLAC SLC detector is described. The module uses a high speed, high resolution analog storage device (AMU) developed in collaboration between SLAC and Stanford University. The AMU devices together with high speed TTL clocking circuitry are packaged in a hybrid which is also suitable for mounting on the detector. The module is in CAMAC format and provides eight signal channels, each recording signal amplitude versus time in 512 cells at a sampling rate of up to 360 MHz. Data are digitized by a 12-bit ADC with a 1 μs conversion time and stored in an on-board memory accessible through CAMAC
12. Waveform Catalog, Extreme Mass Ratio Binary (Capture)
Data.gov (United States)
National Aeronautics and Space Administration — Numerically-generated gravitational waveforms for circular inspiral into Kerr black holes. These waveforms were developed using Scott Hughes' black hole perturbation...
13. Multiples waveform inversion
KAUST Repository
Zhang, Dongliang
2013-01-01
To increase the illumination of the subsurface and to eliminate the dependency of FWI on the source wavelet, we propose multiples waveform inversion (MWI) that transforms each hydrophone into a virtual point source with a time history equal to that of the recorded data. These virtual sources are used to numerically generate downgoing wavefields that are correlated with the backprojected surface-related multiples to give the migration image. Since the recorded data are treated as the virtual sources, knowledge of the source wavelet is not required, and the subsurface illumination is greatly enhanced because the entire free surface acts as an extended source compared to the radiation pattern of a traditional point source. Numerical tests on the Marmousi2 model show that the convergence rate and the spatial resolution of MWI is, respectively, faster and more accurate then FWI. The potential pitfall with this method is that the multiples undergo more than one roundtrip to the surface, which increases attenuation and reduces spatial resolution. This can lead to less resolved tomograms compared to conventional FWI. The possible solution is to combine both FWI and MWI in inverting for the subsurface velocity distribution.
14. Propagation compensation by waveform predistortion
Science.gov (United States)
Halpin, Thomas F.; Urkowitz, Harry; Maron, David E.
Certain modifications of the Cobra Dane radar are considered, particularly modernization of the waveform generator. For wideband waveforms, the dispersive effects of the ionosphere become increasingly significant. The technique of predistorting the transmitted waveform so that a linear chirp is received after two-way passage is one way to overcome that dispersion. This approach is maintained for the modified system, but with a specific predistortion waveform well suited to the modification. The appropriate form of predistortion was derived in an implicit form of time as a function of frequency. The exact form was approximated by Taylor series and pseudo-Chebyshev approximation. The latter proved better, as demonstrated by the resulting smaller loss in detection sensitivity, less coarsening of range resolution, and a lower peak sidelobe. The effects of error in determining the plasma delay constant were determined and are given in graphical form. A suggestion for in-place determination of the plasma delay constant is given.
15. Asymmetric collider
International Nuclear Information System (INIS)
Bharadwaj, V.; Colestock, P.; Goderre, G.; Johnson, D.; Martin, P.; Holt, J.; Kaplan, D.
1993-01-01
The study of CP violation in beauty decay is one of the key challenges facing high energy physics. Much work has not yielded a definitive answer how this study might best be performed. However, one clear conclusion is that new accelerator facilities are needed. Proposals include experiments at asymmetric electron-positron colliders and in fixed-target and collider modes at LHC and SSC. Fixed-target and collider experiments at existing accelerators, while they might succeed in a first observation of the effect, will not be adequate to study it thoroughly. Giomataris has emphasized the potential of a new approach to the study of beauty CP violation: the asymmetric proton collider. Such a collider might be realized by the construction of a small storage ring intersecting an existing or soon-to-exist large synchrotron, or by arranging collisions between a large synchrotron and its injector. An experiment at such a collider can combine the advantages of fixed-target-like spectrometer geometry, facilitating triggering, particle identification and the instrumentation of a large acceptance, while the increased √s can provide a factor > 100 increase in beauty-production cross section compared to Tevatron or HERA fixed-target. Beams crossing at a non-zero angle can provide a small interaction region, permitting a first-level decay-vertex trigger to be implemented. To achieve large √s with a large Lorentz boost and high luminosity, the most favorable venue is the high-energy booster (HEB) at the SSC Laboratory, though the CERN SPS and Fermilab Tevatron are also worth considering
16. A sheath model for arbitrary radiofrequency waveforms
Science.gov (United States)
Turner, M. M.; Chabert, Pascal
2012-10-01
The sheath is often the most important region of a rf plasma, because discharge impedance, power absorption and ion acceleration are critically affected by the behaviour of the sheath. Consequently, models of the sheath are central to any understanding of the physics of rf plasmas. Lieberman has supplied an analytical model for a radio-frequency sheath driven by a single frequency, but in recent years interest has been increasing in radio-frequency discharges excited by increasingly complex wave forms. There has been limited success in generalizing the Lieberman model in this direction, because of mathematical complexities. So there is essentially no sheath model available to describe many modern experiments. In this paper we present a new analytical sheath model, based on a simpler mathematical framework than that of Lieberman. For the single frequency case, this model yields scaling laws that are identical in form to those of Lieberman, differing only by numerical coefficients close to one. However, the new model may be straightforwardly solved for arbitrary current waveforms, and may be used to derive scaling laws for such complex waveforms. In this paper, we will describe the model and present some illustrative examples.
17. Electron Jet of Asymmetric Reconnection
Science.gov (United States)
Khotyaintsev, Yu. V.; Graham, D. B.; Norgren, C.; Eriksson, E.; Li, W.; Johlander, A.; Vaivads, A.; Andre, M.; Pritchett, P. L.; Retino, A.;
2016-01-01
We present Magnetospheric Multiscale observations of an electron-scale current sheet and electron outflow jet for asymmetric reconnection with guide field at the subsolar magnetopause. The electron jet observed within the reconnection region has an electron Mach number of 0.35 and is associated with electron agyrotropy. The jet is unstable to an electrostatic instability which generates intense waves with E(sub parallel lines) amplitudes reaching up to 300 mV/m and potentials up to 20% of the electron thermal energy. We see evidence of interaction between the waves and the electron beam, leading to quick thermalization of the beam and stabilization of the instability. The wave phase speed is comparable to the ion thermal speed, suggesting that the instability is of Buneman type, and therefore introduces electron-ion drag and leads to braking of the electron flow. Our observations demonstrate that electrostatic turbulence plays an important role in the electron-scale physics of asymmetric reconnection.
18. KAUST Repository
Li, Yuanyuan; Li, Zhenchun; Alkhalifah, Tariq Ali; Guo, Qiang
2017-01-01
Elastic full waveform inversion (FWI) provides a better description of the subsurface than those given by the acoustic assumption. However it suffers from a more serious cycle skipping problem compared with the latter. Reflection waveform inversion
19. Asymmetric Ashes
Science.gov (United States)
2006-11-01
that oscillate in certain directions. Reflection or scattering of light favours certain orientations of the electric and magnetic fields over others. This is why polarising sunglasses can filter out the glint of sunlight reflected off a pond. When light scatters through the expanding debris of a supernova, it retains information about the orientation of the scattering layers. If the supernova is spherically symmetric, all orientations will be present equally and will average out, so there will be no net polarisation. If, however, the gas shell is not round, a slight net polarisation will be imprinted on the light. This is what broad-band polarimetry can accomplish. If additional spectral information is available ('spectro-polarimetry'), one can determine whether the asymmetry is in the continuum light or in some spectral lines. In the case of the Type Ia supernovae, the astronomers found that the continuum polarisation is very small so that the overall shape of the explosion is crudely spherical. But the much larger polarization in strongly blue-shifted spectral lines evidences the presence, in the outer regions, of fast moving clumps with peculiar chemical composition. "Our study reveals that explosions of Type Ia supernovae are really three-dimensional phenomena," says Dietrich Baade. "The outer regions of the blast cloud is asymmetric, with different materials found in 'clumps', while the inner regions are smooth." "This study was possible because polarimetry could unfold its full strength thanks to the light-collecting power of the Very Large Telescope and the very precise calibration of the FORS instrument," he adds. The research team first spotted this asymmetry in 2003, as part of the same observational campaign (ESO PR 23/03 and ESO PR Photo 26/05). The new, more extensive results show that the degree of polarisation and, hence, the asphericity, correlates with the intrinsic brightness of the explosion. The brighter the supernova, the smoother, or less clumpy
20. Workflows for Full Waveform Inversions
Science.gov (United States)
Boehm, Christian; Krischer, Lion; Afanasiev, Michael; van Driel, Martin; May, Dave A.; Rietmann, Max; Fichtner, Andreas
2017-04-01
Despite many theoretical advances and the increasing availability of high-performance computing clusters, full seismic waveform inversions still face considerable challenges regarding data and workflow management. While the community has access to solvers which can harness modern heterogeneous computing architectures, the computational bottleneck has fallen to these often manpower-bounded issues that need to be overcome to facilitate further progress. Modern inversions involve huge amounts of data and require a tight integration between numerical PDE solvers, data acquisition and processing systems, nonlinear optimization libraries, and job orchestration frameworks. To this end we created a set of libraries and applications revolving around Salvus (http://salvus.io), a novel software package designed to solve large-scale full waveform inverse problems. This presentation focuses on solving passive source seismic full waveform inversions from local to global scales with Salvus. We discuss (i) design choices for the aforementioned components required for full waveform modeling and inversion, (ii) their implementation in the Salvus framework, and (iii) how it is all tied together by a usable workflow system. We combine state-of-the-art algorithms ranging from high-order finite-element solutions of the wave equation to quasi-Newton optimization algorithms using trust-region methods that can handle inexact derivatives. All is steered by an automated interactive graph-based workflow framework capable of orchestrating all necessary pieces. This naturally facilitates the creation of new Earth models and hopefully sparks new scientific insights. Additionally, and even more importantly, it enhances reproducibility and reliability of the final results.
1. Control and optimization of the slope asymmetry effect in tailored voltage waveforms for capacitively coupled plasmas
International Nuclear Information System (INIS)
Bruneau, B; Novikova, T; Johnson, E V; Lafleur, T; Booth, J P
2015-01-01
Through the use of particle-in-cell simulations, we study the ion flux asymmetry in an argon discharge that is induced by a ‘sawtooth-like’ excitation voltage waveform. In a previous article we have shown that, due to their differing rising and falling slopes, these waveforms can create a plasma with a significantly higher ion flux to one electrode in a geometrically symmetric reactor. Furthermore, they have the unique property of providing a lower ion energy at the electrode with a higher ion flux. In the present work, we show that a refined waveform allows the ion flux asymmetry to be increased for a given number of harmonics by reducing the ionization rate in front of the low-flux electrode. The flux asymmetry is found to disappear at low pressure due to the increased electron energy transport, which causes a transition from sheath edge ionization to bulk ionization. Changing the fundamental frequency is shown to have two counterbalancing effects: reducing the ionization on the low ion-flux electrode and shifting the maximum ionization to the center of the discharge. Under the representative conditions that we have studied, a maximum asymmetry is found for a base frequency of 3.4 MHz. Finally, it is shown that, by adjusting the rise- to fall-time ratio of the refined waveforms, the ion-flux asymmetry can be continuously shifted from one electrode to the other. (paper)
2. Kinetic energies of charged fragments resulting from multifragmentation and asymmetric fission of the C{sub 60} molecule in collisions with monocharged ions (2-130 keV)
Energy Technology Data Exchange (ETDEWEB)
Rentenier, A; Bordenave-Montesquieu, D; Moretto-Capelle, P; Bordenave-Montesquieu, A [Laboratoire CAR-IRSAMC, UMR 5589 CNRS - Universite Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex (France)
2003-04-28
Multifragmentation and asymmetric fission (AF) of the C{sub 60} molecule induced by H{sup +}, H{sub 2}{sup +}, H{sub 3}{sup +} and He{sup +} ions at medium collision energies (2-130 keV) are considered. Momenta and kinetic energies of C{sub n}{sup +} fragment ions (n = 1- 12) are deduced from an analysis of time-of-flight spectra. In multifragmentation processes, momenta are found to be approximately constant when n > 2, a behaviour which explains that the most probable kinetic energy, as well as the width of the kinetic energy distributions, is found to be inversely proportional to the fragment size n; both momenta and kinetic energies are independent of the velocity and nature of the projectile, and hence of the energy deposit. A specific study of the AF shows that the kinetic energies of C{sub 2}{sup +}, C{sub 4}{sup +} and C{sub 6}{sup +} fragments are also independent of the collision velocity and projectile species; a quantitative agreement is found with values deduced from kinetic energy release measurements by another group in electron impact experiments, and the observed decrease when the mass of the light fragment increases is also reproduced. A quantitative comparison of AF and multifragmentation for the n = 2, 4 and 6 fragment ions shows that kinetic energies in AF exceed that in multifragmentation, a result which explains the oscillations observed when momenta or kinetic energies of fragments are plotted against the n-value. The AF yield is also found to scale with the energy deposit in the collision velocity range extending below the velocity at the maximum of the electronic stopping power; except for protons, it remains negligible with respect to multifragmentation as soon as the total energy deposit exceeds about 100 eV.
3. Seismic waveform modeling over cloud
Science.gov (United States)
Luo, Cong; Friederich, Wolfgang
2016-04-01
With the fast growing computational technologies, numerical simulation of seismic wave propagation achieved huge successes. Obtaining the synthetic waveforms through numerical simulation receives an increasing amount of attention from seismologists. However, computational seismology is a data-intensive research field, and the numerical packages usually come with a steep learning curve. Users are expected to master considerable amount of computer knowledge and data processing skills. Training users to use the numerical packages, correctly access and utilize the computational resources is a troubled task. In addition to that, accessing to HPC is also a common difficulty for many users. To solve these problems, a cloud based solution dedicated on shallow seismic waveform modeling has been developed with the state-of-the-art web technologies. It is a web platform integrating both software and hardware with multilayer architecture: a well designed SQL database serves as the data layer, HPC and dedicated pipeline for it is the business layer. Through this platform, users will no longer need to compile and manipulate various packages on the local machine within local network to perform a simulation. By providing users professional access to the computational code through its interfaces and delivering our computational resources to the users over cloud, users can customize the simulation at expert-level, submit and run the job through it.
4. PBX-M waveform generator
International Nuclear Information System (INIS)
Feng, H.; Frank, K.T.; Kaye, S.
1987-01-01
The PBX-M (Princeton Beta Experiment) is an unique Tokamak experiment designed to run with a highly indented plasma. The shaping control will be accomplished through a closed-loop power supply control system. The system will make use of sixteen pre-programmed reference signals and twenty signals taken from direct measurements as input to an analog computer. Through a matrix conversion in the analog computer, these input signals will be used to generate eight control signals to control the eight power supplies. The pre-programmed reference signals will be created using a Macintosh personal computer interfaced to CAMAC (Comptuer Automated Measurement And Control) hardware for down-loading waveforms. The reference signals will be created on the Macintosh by the physics operators, utilizing the full graphics capability of the system. These waveforms are transferred to CAMAC memory, which are then strobed in real time through digital-to-analog converters and fed into the analog computer. The overall system (both hardware and software) is designed to be fail-safe. Specific features of the system, such as load inhibit and discharge inhibit, are discussed
5. Ion peak narrowing by applying additional AC voltage (ripple voltage) to FAIMS extractor electrode.
Science.gov (United States)
Pervukhin, Viktor V; Sheven, Dmitriy G
2010-01-01
The use of a non-uniform electric field in a high-field asymmetric waveform ion mobility spectrometry (FAIMS) analyzer increases sensitivity but decreases resolution. The application of an additional AC voltage to the extractor electrode ("ripple" voltage, U(ripple)) can overcome this effect, which decreases the FAIMS peak width. In this approach, the diffusion ion loss remains minimal in the non-uniform electric field in the cylindrical part of the device, and all ion losses under U(ripple) occur in a short portion of their path. Application of the ripple voltage to the extractor electrode is twice as efficient as the applying of U(ripple) along the total length of the device. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.
6. Test results of pre-production prototype distributed ion pump design for the PEP-II Asymmetric B-Factory collider
Energy Technology Data Exchange (ETDEWEB)
Holdener, F.R.; Behne, D.; Hathaway, D. [and others
1995-04-24
We have built and tested a plate-type pre-production distributed Ion Pump (DIP) for the PEP-II B-Factory High Energy Ring (HER). The design has been an earlier design to use less materials and to costs. Penning cell hole sizes of 15, 18, and 21 mm have been tested in a uniform magnetic field of 0.18 T to optimize pumping speed. The resulting final DIP design consisting of a 7-plate, 15 mm basic cell size anode was magnetic field of the HER dipole. A description of the final optimized DIP design will be presented along with the test results of the pumping speed measurements.
7. Pulsatile pipe flow transition: Flow waveform effects
Science.gov (United States)
Brindise, Melissa C.; Vlachos, Pavlos P.
2018-01-01
Although transition is known to exist in various hemodynamic environments, the mechanisms that govern this flow regime and their subsequent effects on biological parameters are not well understood. Previous studies have investigated transition in pulsatile pipe flow using non-physiological sinusoidal waveforms at various Womersley numbers but have produced conflicting results, and multiple input waveform shapes have yet to be explored. In this work, we investigate the effect of the input pulsatile waveform shape on the mechanisms that drive the onset and development of transition using particle image velocimetry, three pulsatile waveforms, and six mean Reynolds numbers. The turbulent kinetic energy budget including dissipation rate, production, and pressure diffusion was computed. The results show that the waveform with a longer deceleration phase duration induced the earliest onset of transition, while the waveform with a longer acceleration period delayed the onset of transition. In accord with the findings of prior studies, for all test cases, turbulence was observed to be produced at the wall and either dissipated or redistributed into the core flow by pressure waves, depending on the mean Reynolds number. Turbulent production increased with increasing temporal velocity gradients until an asymptotic limit was reached. The turbulence dissipation rate was shown to be independent of mean Reynolds number, but a relationship between the temporal gradients of the input velocity waveform and the rate of turbulence dissipation was found. In general, these results demonstrated that the shape of the input pulsatile waveform directly affected the onset and development of transition.
8. Waveform digitizing at 500 MHz
International Nuclear Information System (INIS)
Atiya, M.; Ito, M.; Haggerty, J.; Ng, C.; Sippach, F.W.
1988-01-01
Experiment E787 at Brookhaven National Laboratory is designed to study the decay K + → π + ν/bar /nu// to a sensitivity of 2 /times/ 10 -10 . To achieve acceptable muon rejection it is necessary to couple traditional methods (range/energy/momentum correlation) with observation of the (π + → μ + ν, μ + → e + ν/bar /nu//) decay sequence in scintillator. We report on the design and construction of 200 channels of relatively low cost solid state waveform digitizers. The distinguishing features are: 8 bits dynamic range, 500 MHz sampling, zero suppression on the fly, deep memory (up to .5 msec), and fast readout time (100 μsec for the entire system). We report on data obtained during the February-May 1988 run showing performance of the system for the observation of the above decay. 8 figs
9. Waveform digitizing at 500 MHz
International Nuclear Information System (INIS)
Atiya, M.; Ito, M.; Haggerty, J.; Ng, C.; Sippach, F.W.
1988-01-01
Experiment E787 at Brookhaven National Laboratory is designed to study the decay K + → π + ν/bar /nu// to a sensitivity of 2 /times/ 10/sup /minus/10/. To achieve acceptable muon rejection it is necessary to couple traditional methods (range/energy/momentum correlation) with observation of the π + → μ + → e + ν/bar /nu// decay sequence in scintillator. We report on the design and construction of over 200 channels of relatively low cost solid state waveform digitizers. The distinguishing features are: 8 bits dynamic range, 500 MHz sampling, zero suppression on the fly, deep memory (up to .5 msec), and fast readout time (100 μsec for the entire system). We report on data obtained during the February--May 1988 run showing performance of the system for the observation of the above decay. 9 figs
10. Multifunction waveform generator for EM receiver testing
Science.gov (United States)
Chen, Kai; Jin, Sheng; Deng, Ming
2018-01-01
In many electromagnetic (EM) methods - such as magnetotelluric, spectral-induced polarization (SIP), time-domain-induced polarization (TDIP), and controlled-source audio magnetotelluric (CSAMT) methods - it is important to evaluate and test the EM receivers during their development stage. To assess the performance of the developed EM receivers, controlled synthetic data that simulate the observed signals in different modes are required. In CSAMT and SIP mode testing, the waveform generator should use the GPS time as the reference for repeating schedule. Based on our testing, the frequency range, frequency precision, and time synchronization of the currently available function waveform generators on the market are deficient. This paper presents a multifunction waveform generator with three waveforms: (1) a wideband, low-noise electromagnetic field signal to be used for magnetotelluric, audio-magnetotelluric, and long-period magnetotelluric studies; (2) a repeating frequency sweep square waveform for CSAMT and SIP studies; and (3) a positive-zero-negative-zero signal that contains primary and secondary fields for TDIP studies. In this paper, we provide the principles of the above three waveforms along with a hardware design for the generator. Furthermore, testing of the EM receiver was conducted with the waveform generator, and the results of the experiment were compared with those calculated from the simulation and theory in the frequency band of interest.
11. Developed vibration waveform monitoring unit for CBM
International Nuclear Information System (INIS)
Hamada, T.; Hotsuta, K.; Hirose, I.; Morita, E.
2007-01-01
In nuclear power plants, many rotating machines such as pumps and fans are in use. Shikoku Research Institute Inc. has recently developed easy-to-use tools to facilitate the maintenance of such equipment. They include a battery-operated vibration waveform monitoring unit which allows unmanned vibration monitoring on a regular basis and data collection even from intermittently operating equipment, a waveform data collector which can be used for easy collection, storage, control, and analysis of raw vibration waveform data during normal operation, and vibration analysis and evaluation tools. A combination of these tools has a high potential for optimization of rotating equipment maintenance. (author)
12. Flow pumping system for physiological waveforms.
Science.gov (United States)
Tsai, William; Savaş, Omer
2010-02-01
A pulsatile flow pumping system is developed to replicate flow waveforms with reasonable accuracy for experiments simulating physiological blood flows at numerous points in the body. The system divides the task of flow waveform generation between two pumps: a gear pump generates the mean component and a piston pump generates the oscillatory component. The system is driven by two programmable servo controllers. The frequency response of the system is used to characterize its operation. The system has been successfully tested in vascular flow experiments where sinusoidal, carotid, and coronary flow waveforms are replicated.
13. Unambiguous range-Doppler LADAR processing using 2 giga-sample-per-second noise waveforms
International Nuclear Information System (INIS)
Cole, Z.; Roos, P.A.; Berg, T.; Kaylor, B.; Merkel, K.D.; Babbitt, W.R.; Reibel, R.R.
2007-01-01
We demonstrate sub-nanosecond range and unambiguous sub-50-Hz Doppler resolved laser radar (LADAR) measurements using spectral holographic processing in rare-earth ion doped crystals. The demonstration utilizes pseudo-random-noise 2 giga-sample-per-second baseband waveforms modulated onto an optical carrier
14. Unambiguous range-Doppler LADAR processing using 2 giga-sample-per-second noise waveforms
Energy Technology Data Exchange (ETDEWEB)
Cole, Z. [S2 Corporation, 2310 University Way 4-1, Bozeman, MT 59715 (United States)]. E-mail: [email protected]; Roos, P.A. [Spectrum Lab, Montana State University, P.O. Box 173510, Bozeman, MT 59717 (United States); Berg, T. [S2 Corporation, 2310 University Way 4-1, Bozeman, MT 59715 (United States); Kaylor, B. [S2 Corporation, 2310 University Way 4-1, Bozeman, MT 59715 (United States); Merkel, K.D. [S2 Corporation, 2310 University Way 4-1, Bozeman, MT 59715 (United States); Babbitt, W.R. [Spectrum Lab, Montana State University, P.O. Box 173510, Bozeman, MT 59717 (United States); Reibel, R.R. [S2 Corporation, 2310 University Way 4-1, Bozeman, MT 59715 (United States)
2007-11-15
We demonstrate sub-nanosecond range and unambiguous sub-50-Hz Doppler resolved laser radar (LADAR) measurements using spectral holographic processing in rare-earth ion doped crystals. The demonstration utilizes pseudo-random-noise 2 giga-sample-per-second baseband waveforms modulated onto an optical carrier.
15. Principles of asymmetric synthesis
CERN Document Server
Gawley, Robert E; Aube, Jeffrey
2012-01-01
The world is chiral. Most of the molecules in it are chiral, and asymmetric synthesis is an important means by which enantiopure chiral molecules may be obtained for study and sale. Using examples from the literature of asymmetric synthesis, this book presents a detailed analysis of the factors that govern stereoselectivity in organic reactions. After an explanation of the basic physical-organic principles governing stereoselective reactions, the authors provide a detailed, annotated glossary of stereochemical terms. A chapter on "Practical Aspects of Asymmetric Synthesis" provides a critical overview of the most common methods for the preparation of enantiomerically pure compounds, techniques for analysis of stereoisomers using chromatographic, spectroscopic, and chiroptical methods. The authors then present an overview of the most important methods in contemporary asymmetric synthesis organized by reaction type. Thus, there are four chapters on carbon-carbon bond forming reactions, one chapter on reductions...
16. Asymmetric bipolar membrane: A tool to improve product purity
NARCIS (Netherlands)
Balster, J.H.; Sumbharaju, R.; Srikantharajah, S.; Punt, Ineke G.M.; Stamatialis, Dimitrios; Jordan, V.; Wessling, Matthias
2007-01-01
Bipolar membranes (BPMs) are catalytic membranes for electro-membrane processes splitting water into protons and hydroxyl ions. To improve selectivity and current efficiency of BPMs, we prepare new asymmetric BPMs with reduced salt leakages. The flux of salt ions across a BPM is determined by the
17. Langmuir waveforms at interplanetary shocks: STEREO statistical analysis
Science.gov (United States)
Briand, C.
2016-12-01
Wave-particle interactions and particle acceleration are the two main processes allowing energy dissipation at non collisional shocks. Ion acceleration has been deeply studied for many years, also for their central role in the shock front reformation. Electron dynamics is also important in the shock dynamics through the instabilities they can generate which may impact the ion dynamics.Particle measurements can be efficiently completed by wave measurements to determine the characteristics of the electron beams and study the turbulence of the medium. Electric waveforms obtained from the S/WAVES instrument of the STEREO mission between 2007 to 2014 are analyzed. Thus, clear signature of Langmuir waves are observed on 41 interplanetary shocks. These data enable a statistical analysis and to deduce some characteristics of the electron dynamics on different shocks sources (SIR or ICME) and types (quasi-perpendicular or quasi-parallel). The conversion process between electrostatic to electromagnetic waves has also been tested in several cases.
18. Seismic waveform classification using deep learning
Science.gov (United States)
Kong, Q.; Allen, R. M.
2017-12-01
MyShake is a global smartphone seismic network that harnesses the power of crowdsourcing. It has an Artificial Neural Network (ANN) algorithm running on the phone to distinguish earthquake motion from human activities recorded by the accelerometer on board. Once the ANN detects earthquake-like motion, it sends a 5-min chunk of acceleration data back to the server for further analysis. The time-series data collected contains both earthquake data and human activity data that the ANN confused. In this presentation, we will show the Convolutional Neural Network (CNN) we built under the umbrella of supervised learning to find out the earthquake waveform. The waveforms of the recorded motion could treat easily as images, and by taking the advantage of the power of CNN processing the images, we achieved very high successful rate to select the earthquake waveforms out. Since there are many non-earthquake waveforms than the earthquake waveforms, we also built an anomaly detection algorithm using the CNN. Both these two methods can be easily extended to other waveform classification problems.
19. Ion Colliders
CERN Document Server
Fischer, W
2014-01-01
High-energy ion colliders are large research tools in nuclear physics to study the Quark-Gluon-Plasma (QGP). The range of collision energy and high luminosity are important design and operational considerations. The experiments also expect flexibility with frequent changes in the collision energy, detector fields, and ion species. Ion species range from protons, including polarized protons in RHIC, to heavy nuclei like gold, lead and uranium. Asymmetric collision combinations (e.g. protons against heavy ions) are also essential. For the creation, acceleration, and storage of bright intense ion beams, limits are set by space charge, charge change, and intrabeam scattering effects, as well as beam losses due to a variety of other phenomena. Currently, there are two operating ion colliders, the Relativistic Heavy Ion Collider (RHIC) at BNL, and the Large Hadron Collider (LHC) at CERN.
20. Thomson scattering measurements from asymmetric interpenetrating plasma flows
Energy Technology Data Exchange (ETDEWEB)
Ross, J. S., E-mail: [email protected]; Moody, J. D.; Fiuza, F.; Ryutov, D.; Divol, L.; Huntington, C. M.; Park, H.-S. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)
2014-11-15
Imaging Thomson scattering measurements of collective ion-acoustic fluctuations have been utilized to determine ion temperature and density from laser produced counter-streaming asymmetric flows. Two foils are heated with 8 laser beams each, 500 J per beam, at the Omega Laser facility. Measurements are made 4 mm from the foil surface using a 60 J 2ω probe laser with a 200 ps pulse length. Measuring the electron density and temperature from the electron-plasma fluctuations constrains the fit of the multi-ion species, asymmetric flows theoretical form factor for the ion feature such that the ion temperatures, ion densities, and flow velocities for each plasma flow are determined.
1. Quantifying social asymmetric structures.
Science.gov (United States)
Solanas, Antonio; Salafranca, Lluís; Riba, Carles; Sierra, Vicenta; Leiva, David
2006-08-01
Many social phenomena involve a set of dyadic relations among agents whose actions may be dependent. Although individualistic approaches have frequently been applied to analyze social processes, these are not generally concerned with dyadic relations, nor do they deal with dependency. This article describes a mathematical procedure for analyzing dyadic interactions in a social system. The proposed method consists mainly of decomposing asymmetric data into their symmetric and skew-symmetric parts. A quantification of skew symmetry for a social system can be obtained by dividing the norm of the skew-symmetric matrix by the norm of the asymmetric matrix. This calculation makes available to researchers a quantity related to the amount of dyadic reciprocity. With regard to agents, the procedure enables researchers to identify those whose behavior is asymmetric with respect to all agents. It is also possible to derive symmetric measurements among agents and to use multivariate statistical techniques.
2. Asymmetrical field emitter
Science.gov (United States)
Fleming, J.G.; Smith, B.K.
1995-10-10
A method is disclosed for providing a field emitter with an asymmetrical emitter structure having a very sharp tip in close proximity to its gate. One preferred embodiment of the present invention includes an asymmetrical emitter and a gate. The emitter having a tip and a side is coupled to a substrate. The gate is connected to a step in the substrate. The step has a top surface and a side wall that is substantially parallel to the side of the emitter. The tip of the emitter is in close proximity to the gate. The emitter is at an emitter potential, and the gate is at a gate potential such that with the two potentials at appropriate values, electrons are emitted from the emitter. In one embodiment, the gate is separated from the emitter by an oxide layer, and the emitter is etched anisotropically to form its tip and its asymmetrical structure. 17 figs.
3. Design of pulse waveform for waveform division multiple access UWB wireless communication system.
Science.gov (United States)
Yin, Zhendong; Wang, Zhirui; Liu, Xiaohui; Wu, Zhilu
2014-01-01
A new multiple access scheme, Waveform Division Multiple Access (WDMA) based on the orthogonal wavelet function, is presented. After studying the correlation properties of different categories of single wavelet functions, the one with the best correlation property will be chosen as the foundation for combined waveform. In the communication system, each user is assigned to different combined orthogonal waveform. Demonstrated by simulation, combined waveform is more suitable than single wavelet function to be a communication medium in WDMA system. Due to the excellent orthogonality, the bit error rate (BER) of multiuser with combined waveforms is so close to that of single user in a synchronous system. That is to say, the multiple access interference (MAI) is almost eliminated. Furthermore, even in an asynchronous system without multiuser detection after matched filters, the result is still pretty ideal and satisfactory by using the third combination mode that will be mentioned in the study.
4. SCA Waveform Development for Space Telemetry
Science.gov (United States)
Mortensen, Dale J.; Kifle, Multi; Hall, C. Steve; Quinn, Todd M.
2004-01-01
The NASA Glenn Research Center is investigating and developing suitable reconfigurable radio architectures for future NASA missions. This effort is examining software-based open-architectures for space based transceivers, as well as common hardware platform architectures. The Joint Tactical Radio System's (JTRS) Software Communications Architecture (SCA) is a candidate for the software approach, but may need modifications or adaptations for use in space. An in-house SCA compliant waveform development focuses on increasing understanding of software defined radio architectures and more specifically the JTRS SCA. Space requirements put a premium on size, mass, and power. This waveform development effort is key to evaluating tradeoffs with the SCA for space applications. Existing NASA telemetry links, as well as Space Exploration Initiative scenarios, are the basis for defining the waveform requirements. Modeling and simulations are being developed to determine signal processing requirements associated with a waveform and a mission-specific computational burden. Implementation of the waveform on a laboratory software defined radio platform is proceeding in an iterative fashion. Parallel top-down and bottom-up design approaches are employed.
5. WFCatalog: A catalogue for seismological waveform data
Science.gov (United States)
Trani, Luca; Koymans, Mathijs; Atkinson, Malcolm; Sleeman, Reinoud; Filgueira, Rosa
2017-09-01
This paper reports advances in seismic waveform description and discovery leading to a new seismological service and presents the key steps in its design, implementation and adoption. This service, named WFCatalog, which stands for waveform catalogue, accommodates features of seismological waveform data. Therefore, it meets the need for seismologists to be able to select waveform data based on seismic waveform features as well as sensor geolocations and temporal specifications. We describe the collaborative design methods and the technical solution showing the central role of seismic feature catalogues in framing the technical and operational delivery of the new service. Also, we provide an overview of the complex environment wherein this endeavour is scoped and the related challenges discussed. As multi-disciplinary, multi-organisational and global collaboration is necessary to address today's challenges, canonical representations can provide a focus for collaboration and conceptual tools for agreeing directions. Such collaborations can be fostered and formalised by rallying intellectual effort into the design of novel scientific catalogues and the services that support them. This work offers an example of the benefits generated by involving cross-disciplinary skills (e.g. data and domain expertise) from the early stages of design, and by sustaining the engagement with the target community throughout the delivery and deployment process.
6. Photonic arbitrary waveform generator based on Taylor synthesis method
DEFF Research Database (Denmark)
Liao, Shasha; Ding, Yunhong; Dong, Jianji
2016-01-01
Arbitrary waveform generation has been widely used in optical communication, radar system and many other applications. We propose and experimentally demonstrate a silicon-on-insulator (SOI) on chip optical arbitrary waveform generator, which is based on Taylor synthesis method. In our scheme......, a Gaussian pulse is launched to some cascaded microrings to obtain first-, second- and third-order differentiations. By controlling amplitude and phase of the initial pulse and successive differentiations, we can realize an arbitrary waveform generator according to Taylor expansion. We obtain several typical...... waveforms such as square waveform, triangular waveform, flat-top waveform, sawtooth waveform, Gaussian waveform and so on. Unlike other schemes based on Fourier synthesis or frequency-to-time mapping, our scheme is based on Taylor synthesis method. Our scheme does not require any spectral disperser or large...
7. Wavelet analysis of the impedance cardiogram waveforms
Science.gov (United States)
Podtaev, S.; Stepanov, R.; Dumler, A.; Chugainov, S.; Tziberkin, K.
2012-12-01
Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt)max) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.
8. Wavelet analysis of the impedance cardiogram waveforms
International Nuclear Information System (INIS)
Podtaev, S; Stepanov, R; Dumler, A; Chugainov, S; Tziberkin, K
2012-01-01
Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt) max ) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.
9. Krylov subspace acceleration of waveform relaxation
Energy Technology Data Exchange (ETDEWEB)
Lumsdaine, A.; Wu, Deyun [Univ. of Notre Dame, IN (United States)
1996-12-31
Standard solution methods for numerically solving time-dependent problems typically begin by discretizing the problem on a uniform time grid and then sequentially solving for successive time points. The initial time discretization imposes a serialization to the solution process and limits parallel speedup to the speedup available from parallelizing the problem at any given time point. This bottleneck can be circumvented by the use of waveform methods in which multiple time-points of the different components of the solution are computed independently. With the waveform approach, a problem is first spatially decomposed and distributed among the processors of a parallel machine. Each processor then solves its own time-dependent subsystem over the entire interval of interest using previous iterates from other processors as inputs. Synchronization and communication between processors take place infrequently, and communication consists of large packets of information - discretized functions of time (i.e., waveforms).
10. Waveform Design for Wireless Power Transfer
Science.gov (United States)
Clerckx, Bruno; Bayguzina, Ekaterina
2016-12-01
Far-field Wireless Power Transfer (WPT) has attracted significant attention in recent years. Despite the rapid progress, the emphasis of the research community in the last decade has remained largely concentrated on improving the design of energy harvester (so-called rectenna) and has left aside the effect of transmitter design. In this paper, we study the design of transmit waveform so as to enhance the DC power at the output of the rectenna. We derive a tractable model of the non-linearity of the rectenna and compare with a linear model conventionally used in the literature. We then use those models to design novel multisine waveforms that are adaptive to the channel state information (CSI). Interestingly, while the linear model favours narrowband transmission with all the power allocated to a single frequency, the non-linear model favours a power allocation over multiple frequencies. Through realistic simulations, waveforms designed based on the non-linear model are shown to provide significant gains (in terms of harvested DC power) over those designed based on the linear model and over non-adaptive waveforms. We also compute analytically the theoretical scaling laws of the harvested energy for various waveforms as a function of the number of sinewaves and transmit antennas. Those scaling laws highlight the benefits of CSI knowledge at the transmitter in WPT and of a WPT design based on a non-linear rectenna model over a linear model. Results also motivate the study of a promising architecture relying on large-scale multisine multi-antenna waveforms for WPT. As a final note, results stress the importance of modeling and accounting for the non-linearity of the rectenna in any system design involving wireless power.
11. How Is Nature Asymmetric?
Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 6. How Is Nature Asymmetric? - Discrete Symmetries in Particle Physics and their Violation ... Indian Institute of Technology, Chennai. Aligarh Muslim University. University of Rajasthan, Jaipur. Indian Institute of Science, Bangalore 560012, India.
12. Exploring asymmetric catalytic transformations
NARCIS (Netherlands)
Guduguntla, Sureshbabu
2017-01-01
In Chapter 2, we report a highly enantioselective synthesis of β-alkyl-substituted alcohols through a one-pot Cu- catalyzed asymmetric allylic alkylation with organolithium reagents followed by reductive ozonolysis. The synthesis of γ-alkyl-substituted alcohols was also achieved through Cu-catalyzed
13. Principles of waveform diversity and design
CERN Document Server
Wicks, Michael
2011-01-01
This is the first book to discuss current and future applications of waveform diversity and design in subjects such as radar and sonar, communications systems, passive sensing, and many other technologies. Waveform diversity allows researchers and system designers to optimize electromagnetic and acoustic systems for sensing, communications, electronic warfare or combinations thereof. This book enables solutions to problems, explaining how each system performs its own particular function, as well as how it is affected by other systems and how those other systems may likewise be affected. It is
14. Signal processing in noise waveform radar
CERN Document Server
Kulpa, Krzysztof
2013-01-01
This book is devoted to the emerging technology of noise waveform radar and its signal processing aspects. It is a new kind of radar, which use noise-like waveform to illuminate the target. The book includes an introduction to basic radar theory, starting from classical pulse radar, signal compression, and wave radar. The book then discusses the properties, difficulties and potential of noise radar systems, primarily for low-power and short-range civil applications. The contribution of modern signal processing techniques to making noise radar practical are emphasized, and application examples
15. Current drive by asymmetrical heating in a toroidal plasma
International Nuclear Information System (INIS)
Gahl, J.M.
1986-01-01
This report describes the first experimental observation of current generation by asymmetrical heating of ions. A unidirectional fast Alfven wave launched by a slow-wave antenna inside the Texas Tech Tokamak, asymmetrically heated the ions. Measurements of the asymmetry of the toroidal plasma current with probes at the top and bottom of the toroidal plasma column confirmed the current generation indirectly. Current generation, obtained in a one-species, hydrogen plasma, is a phenomenon which had not been predicted previously. Calculations of the dispersion relation for the fast Alfven wave near the fundamental cyclotron resonance in a one-species, hydrogen plasma, using warm plasma theory, support the experimental results
16. Waveform relaxation methods for implicit differential equations
NARCIS (Netherlands)
P.J. van der Houwen; W.A. van der Veen
1996-01-01
textabstractWe apply a Runge-Kutta-based waveform relaxation method to initial-value problems for implicit differential equations. In the implementation of such methods, a sequence of nonlinear systems has to be solved iteratively in each step of the integration process. The size of these systems
17. A multi-channel waveform digitizer system
International Nuclear Information System (INIS)
Bieser, F.; Muller, W.F.J.
1990-01-01
The authors report on the design and performance of a multichannel waveform digitizer system for use with the Multiple Sample Ionization Chamber (MUSIC) Detector at the Bevalac. 128 channels of 20 MHz Flash ADC plus 256 word deep memory are housed in a single crate. Digital thresholds and hit pattern logic facilitate zero suppression during readout which is performed over a standard VME bus
18. Resolution analysis in full waveform inversion
NARCIS (Netherlands)
Fichtner, A.; Trampert, J.
2011-01-01
We propose a new method for the quantitative resolution analysis in full seismic waveform inversion that overcomes the limitations of classical synthetic inversions while being computationally more efficient and applicable to any misfit measure. The method rests on (1) the local quadratic
19. Classification of morphologic changes in photoplethysmographic waveforms
Directory of Open Access Journals (Sweden)
Tigges Timo
2016-09-01
Full Text Available An ever increasing number of research is examining the question to what extent physiological information beyond the blood oxygen saturation could be drawn from the photoplethysmogram. One important approach to elicit that information from the photoplethysmogram is the analysis of its waveform. One prominent example for the value of photoplethysmographic waveform analysis in cardiovascular monitoring that has emerged is hemodynamic compensation assessment in the peri-operative setting or trauma situations, as digital pulse waveform dynamically changes with alterations in vascular tone or pulse wave velocity. In this work, we present an algorithm based on modern machine learning techniques that automatically finds individual digital volume pulses in photoplethysmographic signals and sorts them into one of the pulse classes defined by Dawber et al. We evaluate our approach based on two major datasets – a measurement study that we conducted ourselves as well as data from the PhysioNet MIMIC II database. As the results are satisfying we could demonstrate the capabilities of classification algorithms in the automated assessment of the digital volume pulse waveform measured by photoplethysmographic devices.
20. Full-waveform inversion: Filling the gaps
KAUST Repository
Beydoun, Wafik B.; Alkhalifah, Tariq Ali
2015-01-01
After receiving an outstanding response to its inaugural workshop in 2013, SEG once again achieved great success with its 2015 SEG Middle East Workshop, “Full-waveform inversion: Filling the gaps,” which took place 30 March–1 April 2015 in Abu Dhabi
1. Origin of Asymmetric Charge Partitioning in the Dissociation of Gas-Phase Protein Homodimers
OpenAIRE
Jurchen, John C.; Williams, Evan R.
2003-01-01
The origin of asymmetric charge and mass partitioning observed for gas-phase dissociation of multiply charged macromolecular complexes has been hotly debated. These experiments hold the potential to provide detailed information about the interactions between the macromolecules within the complex. Here, this unusual phenomenon of asymmetric charge partitioning is investigated for several protein homodimers. Asymmetric charge partitioning in these ions depends on a number of factors, including ...
2. Source-independent elastic waveform inversion using a logarithmic wavefield
KAUST Repository
Choi, Yun Seok; Min, Dong Joon
2012-01-01
The logarithmic waveform inversion has been widely developed and applied to some synthetic and real data. In most logarithmic waveform inversion algorithms, the subsurface velocities are updated along with the source estimation. To avoid estimating
3. Multiparameter Elastic Full Waveform Inversion with Facies-based Constraints
KAUST Repository
Zhang, Zhendong; Alkhalifah, Tariq Ali; Naeini, Ehsan Zabihi; Sun, Bingbing
2018-01-01
Full waveform inversion (FWI) incorporates all the data characteristics to estimate the parameters described by the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion beyond improved acoustic imaging, like
4. Waveform inversion for acoustic VTI media in frequency domain
KAUST Repository
Wu, Zedong; Alkhalifah, Tariq Ali
2016-01-01
Reflected waveform inversion (RWI) provides a method to reduce the nonlinearity of the standard full waveform inversion (FWI) by inverting for the background model using a single scattered wavefield from an inverted perturbation. However, current
5. Multiparameter Elastic Full Waveform Inversion With Facies Constraints
KAUST Repository
Zhang, Zhendong; Alkhalifah, Tariq Ali; Naeini, Ehsan Zabihi
2017-01-01
Full waveform inversion (FWI) aims fully benefit from all the data characteristics to estimate the parameters describing the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion as a tool beyond acoustic
6. Generation of correlated finite alphabet waveforms using gaussian random variables
KAUST Repository
Jardak, Seifallah; Ahmed, Sajid; Alouini, Mohamed-Slim
2014-01-01
, the proposed scheme is general, the main focus of this paper is to generate finite alphabet waveforms for multiple-input multiple-output radar, where correlated waveforms are used to achieve desired beampatterns. © 2014 IEEE.
7. Towards full waveform ambient noise inversion
Science.gov (United States)
Sager, Korbinian; Ermert, Laura; Boehm, Christian; Fichtner, Andreas
2018-01-01
In this work we investigate fundamentals of a method—referred to as full waveform ambient noise inversion—that improves the resolution of tomographic images by extracting waveform information from interstation correlation functions that cannot be used without knowing the distribution of noise sources. The fundamental idea is to drop the principle of Green function retrieval and to establish correlation functions as self-consistent observables in seismology. This involves the following steps: (1) We introduce an operator-based formulation of the forward problem of computing correlation functions. It is valid for arbitrary distributions of noise sources in both space and frequency, and for any type of medium, including 3-D elastic, heterogeneous and attenuating media. In addition, the formulation allows us to keep the derivations independent of time and frequency domain and it facilitates the application of adjoint techniques, which we use to derive efficient expressions to compute first and also second derivatives. The latter are essential for a resolution analysis that accounts for intra- and interparameter trade-offs. (2) In a forward modelling study we investigate the effect of noise sources and structure on different observables. Traveltimes are hardly affected by heterogeneous noise source distributions. On the other hand, the amplitude asymmetry of correlations is at least to first order insensitive to unmodelled Earth structure. Energy and waveform differences are sensitive to both structure and the distribution of noise sources. (3) We design and implement an appropriate inversion scheme, where the extraction of waveform information is successively increased. We demonstrate that full waveform ambient noise inversion has the potential to go beyond ambient noise tomography based on Green function retrieval and to refine noise source location, which is essential for a better understanding of noise generation. Inherent trade-offs between source and structure
8. Multipartite asymmetric quantum cloning
International Nuclear Information System (INIS)
Iblisdir, S.; Gisin, N.; Acin, A.; Cerf, N.J.; Filip, R.; Fiurasek, J.
2005-01-01
We investigate the optimal distribution of quantum information over multipartite systems in asymmetric settings. We introduce cloning transformations that take N identical replicas of a pure state in any dimension as input and yield a collection of clones with nonidentical fidelities. As an example, if the clones are partitioned into a set of M A clones with fidelity F A and another set of M B clones with fidelity F B , the trade-off between these fidelities is analyzed, and particular cases of optimal N→M A +M B cloning machines are exhibited. We also present an optimal 1→1+1+1 cloning machine, which is an example of a tripartite fully asymmetric cloner. Finally, it is shown how these cloning machines can be optically realized
9. Retrieving rupture history using waveform inversions in time sequence
Science.gov (United States)
Yi, L.; Xu, C.; Zhang, X.
2017-12-01
The rupture history of large earthquakes is generally regenerated using the waveform inversion through utilizing seismological waveform records. In the waveform inversion, based on the superposition principle, the rupture process is linearly parameterized. After discretizing the fault plane into sub-faults, the local source time function of each sub-fault is usually parameterized using the multi-time window method, e.g., mutual overlapped triangular functions. Then the forward waveform of each sub-fault is synthesized through convoluting the source time function with its Green function. According to the superposition principle, these forward waveforms generated from the fault plane are summarized in the recorded waveforms after aligning the arrival times. Then the slip history is retrieved using the waveform inversion method after the superposing of all forward waveforms for each correspond seismological waveform records. Apart from the isolation of these forward waveforms generated from each sub-fault, we also realize that these waveforms are gradually and sequentially superimposed in the recorded waveforms. Thus we proposed a idea that the rupture model is possibly detachable in sequent rupture times. According to the constrained waveform length method emphasized in our previous work, the length of inverted waveforms used in the waveform inversion is objectively constrained by the rupture velocity and rise time. And one essential prior condition is the predetermined fault plane that limits the duration of rupture time, which means the waveform inversion is restricted in a pre-set rupture duration time. Therefore, we proposed a strategy to inverse the rupture process sequentially using the progressively shift rupture times as the rupture front expanding in the fault plane. And we have designed a simulation inversion to test the feasibility of the method. Our test result shows the prospect of this idea that requiring furthermore investigation.
10. Asymmetric information and economics
Science.gov (United States)
Frieden, B. Roy; Hawkins, Raymond J.
2010-01-01
We present an expression of the economic concept of asymmetric information with which it is possible to derive the dynamical laws of an economy. To illustrate the utility of this approach we show how the assumption of optimal information flow leads to a general class of investment strategies including the well-known Q theory of Tobin. Novel consequences of this formalism include a natural definition of market efficiency and an uncertainty principle relating capital stock and investment flow.
11. Asymmetric Evolutionary Games
Science.gov (United States)
McAvoy, Alex; Hauert, Christoph
2015-01-01
Evolutionary game theory is a powerful framework for studying evolution in populations of interacting individuals. A common assumption in evolutionary game theory is that interactions are symmetric, which means that the players are distinguished by only their strategies. In nature, however, the microscopic interactions between players are nearly always asymmetric due to environmental effects, differing baseline characteristics, and other possible sources of heterogeneity. To model these phenomena, we introduce into evolutionary game theory two broad classes of asymmetric interactions: ecological and genotypic. Ecological asymmetry results from variation in the environments of the players, while genotypic asymmetry is a consequence of the players having differing baseline genotypes. We develop a theory of these forms of asymmetry for games in structured populations and use the classical social dilemmas, the Prisoner’s Dilemma and the Snowdrift Game, for illustrations. Interestingly, asymmetric games reveal essential differences between models of genetic evolution based on reproduction and models of cultural evolution based on imitation that are not apparent in symmetric games. PMID:26308326
12. Prototype of a transient waveform recording ASIC
Science.gov (United States)
Qin, J.; Zhao, L.; Cheng, B.; Chen, H.; Guo, Y.; Liu, S.; An, Q.
2018-01-01
The paper presents the design and measurement results of a transient waveform recording ASIC based on the Switched Capacitor Array (SCA) architecture. This 0.18 μm CMOS prototype device contains two channels and each channel employs a SCA of 128 samples deep, a 12-bit Wilkinson ADC and a serial data readout. A series of tests have been conducted and the results indicate that: a full 1 V signal voltage range is available, the input analog bandwidth is approximately 450 MHz and the sampling speed is adjustable from 0.076 to 3.2 Gsps (Gigabit Samples Per Second). For precision waveform timing extraction, careful calibration of timing intervals between samples is conducted to improve the timing resolution of such chips, and the timing precision of this ASIC is proved to be better than 15 ps RMS.
13. Digitizing and analysis of neutron generator waveforms
International Nuclear Information System (INIS)
Bryant, T.C.
1977-11-01
All neutron generator waveforms from units tested at the SLA neutron generator test site are digitized and the digitized data stored in the CDC 6600 tape library for display and analysis using the CDC 6600 computer. The digitizing equipment consists mainly of seven Biomation Model 8100 transient recorders, Digital Equipment Corporation PDP 11/20 computer, RK05 disk, seven-track magnetic tape transport, and appropriate DEC and SLA controllers and interfaces. The PDP 11/20 computer is programmed in BASIC with assembly language drivers. In addition to digitizing waveforms, this equipment is used for other functions such as the automated testing of multiple-operation electronic neutron generators. Although other types of analysis have been done, the largest use of the digitized data has been for various types of graphical displays using the CDC 6600 and either the SD4020 or DX4460 plotters
14. Programmable Clock Waveform Generation for CCD Readout
Energy Technology Data Exchange (ETDEWEB)
Vicente, J. de; Castilla, J.; Martinez, G.; Marin, J.
2006-07-01
Charge transfer efficiency in CCDs is closely related to the clock waveform. In this paper, an experimental framework to explore different FPGA based clock waveform generator designs is described. Two alternative design approaches for controlling the rise/fall edge times and pulse width of the CCD clock signal have been implemented: level-control and time-control. Both approaches provide similar characteristics regarding the edge linearity and noise. Nevertheless, dissimilarities have been found with respect to the area and frequency range of application. Thus, while the time-control approach consumes less area, the level control approach provides a wider range of clock frequencies since it does not suffer capacitor discharge effect. (Author) 8 refs.
15. Induced waveform transitions of dissipative solitons
Science.gov (United States)
Kochetov, Bogdan A.; Tuz, Vladimir R.
2018-01-01
The effect of an externally applied force upon the dynamics of dissipative solitons is analyzed in the framework of the one-dimensional cubic-quintic complex Ginzburg-Landau equation supplemented by a potential term with an explicit coordinate dependence. The potential accounts for the external force manipulations and consists of three symmetrically arranged potential wells whose depth varies along the longitudinal coordinate. It is found out that under an influence of such potential a transition between different soliton waveforms coexisting under the same physical conditions can be achieved. A low-dimensional phase-space analysis is applied in order to demonstrate that by only changing the potential profile, transitions between different soliton waveforms can be performed in a controllable way. In particular, it is shown that by means of a selected potential, stationary dissipative soliton can be transformed into another stationary soliton as well as into periodic, quasi-periodic, and chaotic spatiotemporal dissipative structures.
16. QUARTZ: a numerical simulation of an asymmetric electrostatic accelerator
International Nuclear Information System (INIS)
Wooten, J.W.; Drooks, L.J.; McCollough, D.H.; McGaffey, R.W.; Whealton, J.H.
1979-01-01
The physics and numerical aspects of the development of the computer code QUARTZ are given. This code includes the (1) use of a finite element code to obtain solutions of Poisson's equation in an asymmetric, three-dimensional volume; (2) inclusion of space charge neutralization by electrons; and (3) inclusion of ion space charge through an iterative procedure
17. Advanced Waveform Simulation for Seismic Monitoring
Science.gov (United States)
2008-09-01
velocity model. The method separates the main arrivals of the regional waveform into 5 windows: Pnl (vertical and radial components), Rayleigh (vertical and...ranges out to 10°, including extensive observations of crustal thinning and thickening and various Pnl complexities. Broadband modeling in 1D, 2D...existing models perform in predicting the various regional phases, Rayleigh waves, Love waves, and Pnl waves. Previous events from this Basin-and-Range
18. Full-waveform inversion: Filling the gaps
KAUST Repository
Beydoun, Wafik B.
2015-09-01
After receiving an outstanding response to its inaugural workshop in 2013, SEG once again achieved great success with its 2015 SEG Middle East Workshop, “Full-waveform inversion: Filling the gaps,” which took place 30 March–1 April 2015 in Abu Dhabi, UAE. The workshop was organized by SEG, and its partner sponsors were Saudi Aramco (gold sponsor), ExxonMobil, and CGG. Read More: http://library.seg.org/doi/10.1190/tle34091106.1
19. Integration and interpolation of sampled waveforms
International Nuclear Information System (INIS)
Stearns, S.D.
1978-01-01
Methods for integrating, interpolating, and improving the signal-to-noise ratio of digitized waveforms are discussed with regard to seismic data from underground tests. The frequency-domain integration method and the digital interpolation method of Schafer and Rabiner are described and demonstrated using test data. The use of bandpass filtering for noise reduction is also demonstrated. With these methods, a backlog of seismic test data has been successfully processed
20. Time-dependent phase error correction using digital waveform synthesis
Science.gov (United States)
Doerry, Armin W.; Buskirk, Stephen
2017-10-10
The various technologies presented herein relate to correcting a time-dependent phase error generated as part of the formation of a radar waveform. A waveform can be pre-distorted to facilitate correction of an error induced into the waveform by a downstream operation/component in a radar system. For example, amplifier power droop effect can engender a time-dependent phase error in a waveform as part of a radar signal generating operation. The error can be quantified and an according complimentary distortion can be applied to the waveform to facilitate negation of the error during the subsequent processing of the waveform. A time domain correction can be applied by a phase error correction look up table incorporated into a waveform phase generator.
1. Sparse Frequency Waveform Design for Radar-Embedded Communication
Directory of Open Access Journals (Sweden)
Chaoyun Mai
2016-01-01
Full Text Available According to the Tag application with function of covert communication, a method for sparse frequency waveform design based on radar-embedded communication is proposed. Firstly, sparse frequency waveforms are designed based on power spectral density fitting and quasi-Newton method. Secondly, the eigenvalue decomposition of the sparse frequency waveform sequence is used to get the dominant space. Finally the communication waveforms are designed through the projection of orthogonal pseudorandom vectors in the vertical subspace. Compared with the linear frequency modulation waveform, the sparse frequency waveform can further improve the bandwidth occupation of communication signals, thus achieving higher communication rate. A certain correlation exists between the reciprocally orthogonal communication signals samples and the sparse frequency waveform, which guarantees the low SER (signal error rate and LPI (low probability of intercept. The simulation results verify the effectiveness of this method.
2. Image-domain full waveform inversion
KAUST Repository
Zhang, Sanzong
2013-08-20
The main difficulty with the data-domain full waveform inversion (FWI) is that it tends to get stuck in the local minima associated with the waveform misfit function. This is because the waveform misfit function is highly nonlinear with respect to changes in velocity model. To reduce this nonlinearity, we define the image-domain objective function to minimize the difference of the suboffset-domain common image gathers (CIGs) obtained by migrating the observed data and the calculated data. The derivation shows that the gradient of this new objective function is the combination of the gradient of the conventional FWI and the image-domain differential semblance optimization (DSO). Compared to the conventional FWI, the imagedomain FWI is immune to cycle skipping problems by smearing the nonzero suboffset images along wavepath. It also can avoid the edge effects and the gradient artifacts that are inherent in DSO due to the falsely over-penalized focused images. This is achieved by subtracting the focused image associated with the calculated data from the unfocused image associated with the observed data in the image-domain misfit function. The numerical results of the Marmousi model show that image-domain FWI is less sensitive the initial model than the conventional FWI. © 2013 SEG.
3. Image-domain full waveform inversion
KAUST Repository
Zhang, Sanzong; Schuster, Gerard T.
2013-01-01
The main difficulty with the data-domain full waveform inversion (FWI) is that it tends to get stuck in the local minima associated with the waveform misfit function. This is because the waveform misfit function is highly nonlinear with respect to changes in velocity model. To reduce this nonlinearity, we define the image-domain objective function to minimize the difference of the suboffset-domain common image gathers (CIGs) obtained by migrating the observed data and the calculated data. The derivation shows that the gradient of this new objective function is the combination of the gradient of the conventional FWI and the image-domain differential semblance optimization (DSO). Compared to the conventional FWI, the imagedomain FWI is immune to cycle skipping problems by smearing the nonzero suboffset images along wavepath. It also can avoid the edge effects and the gradient artifacts that are inherent in DSO due to the falsely over-penalized focused images. This is achieved by subtracting the focused image associated with the calculated data from the unfocused image associated with the observed data in the image-domain misfit function. The numerical results of the Marmousi model show that image-domain FWI is less sensitive the initial model than the conventional FWI. © 2013 SEG.
4. Asymmetric quantum cloning machines
International Nuclear Information System (INIS)
Cerf, N.J.
1998-01-01
A family of asymmetric cloning machines for quantum bits and N-dimensional quantum states is introduced. These machines produce two approximate copies of a single quantum state that emerge from two distinct channels. In particular, an asymmetric Pauli cloning machine is defined that makes two imperfect copies of a quantum bit, while the overall input-to-output operation for each copy is a Pauli channel. A no-cloning inequality is derived, characterizing the impossibility of copying imposed by quantum mechanics. If p and p ' are the probabilities of the depolarizing channels associated with the two outputs, the domain in (√p,√p ' )-space located inside a particular ellipse representing close-to-perfect cloning is forbidden. This ellipse tends to a circle when copying an N-dimensional state with N→∞, which has a simple semi-classical interpretation. The symmetric Pauli cloning machines are then used to provide an upper bound on the quantum capacity of the Pauli channel of probabilities p x , p y and p z . The capacity is proven to be vanishing if (√p x , √p y , √p z ) lies outside an ellipsoid whose pole coincides with the depolarizing channel that underlies the universal cloning machine. Finally, the tradeoff between the quality of the two copies is shown to result from a complementarity akin to Heisenberg uncertainty principle. (author)
5. Cinchona alkaloids in asymmetric organocatalysis
NARCIS (Netherlands)
Marcelli, T.; Hiemstra, H.
2010-01-01
This article reviews the applications of cinchona alkaloids as asymmetric catalysts. In the last few years, characterized by the resurgence of interest in asymmetric organocatalysis, cinchona derivatives have been shown to catalyze an outstanding array of chemical reactions, often with remarkable
6. Alternative Asymmetric Stochastic Volatility Models
NARCIS (Netherlands)
M. Asai (Manabu); M.J. McAleer (Michael)
2010-01-01
textabstractThe stochastic volatility model usually incorporates asymmetric effects by introducing the negative correlation between the innovations in returns and volatility. In this paper, we propose a new asymmetric stochastic volatility model, based on the leverage and size effects. The model is
7. Asymmetric Realized Volatility Risk
Directory of Open Access Journals (Sweden)
David E. Allen
2014-06-01
Full Text Available In this paper, we document that realized variation measures constructed from high-frequency returns reveal a large degree of volatility risk in stock and index returns, where we characterize volatility risk by the extent to which forecasting errors in realized volatility are substantive. Even though returns standardized by ex post quadratic variation measures are nearly Gaussian, this unpredictability brings considerably more uncertainty to the empirically relevant ex ante distribution of returns. Explicitly modeling this volatility risk is fundamental. We propose a dually asymmetric realized volatility model, which incorporates the fact that realized volatility series are systematically more volatile in high volatility periods. Returns in this framework display time varying volatility, skewness and kurtosis. We provide a detailed account of the empirical advantages of the model using data on the S&P 500 index and eight other indexes and stocks.
8. Asymmetric Higgsino dark matter.
Science.gov (United States)
Blum, Kfir; Efrati, Aielet; Grossman, Yuval; Nir, Yosef; Riotto, Antonio
2012-08-03
In the supersymmetric framework, prior to the electroweak phase transition, the existence of a baryon asymmetry implies the existence of a Higgsino asymmetry. We investigate whether the Higgsino could be a viable asymmetric dark matter candidate. We find that this is indeed possible. Thus, supersymmetry can provide the observed dark matter abundance and, furthermore, relate it with the baryon asymmetry, in which case the puzzle of why the baryonic and dark matter mass densities are similar would be explained. To accomplish this task, two conditions are required. First, the gauginos, squarks, and sleptons must all be very heavy, such that the only electroweak-scale superpartners are the Higgsinos. With this spectrum, supersymmetry does not solve the fine-tuning problem. Second, the temperature of the electroweak phase transition must be low, in the (1-10) GeV range. This condition requires an extension of the minimal supersymmetric standard model.
DEFF Research Database (Denmark)
Mose, Rasmus
2016-01-01
has gained broad recognition as it has found several applications in academia and industry. The [4+2] cycloaddition has also been performed in an enantioselective aminocatalytic fashion which allows the generation of optically active products. In this thesis it is demonstrated how trienamines can......Since the onset of the new millennium the field of organocatalysis has undergone a great expansion led by investigations in the field of aminocatalysis. This thesis will address some recent developments in aminocatalyzed cycloadditions and provide a theoretical background hereto. Cycloadditions...... undergo cascade reactions with different electron deficient dienophiles in Diels Alder – nucleophilic ring closing reactions. This methodology opens up for the direct asymmetric formation of hydroisochromenes and hydroisoquinolines which may possess interesting biological activities. It is also...
10. Best waveform score for diagnosing keratoconus
Directory of Open Access Journals (Sweden)
Allan Luz
2013-12-01
Full Text Available PURPOSE: To test whether corneal hysteresis (CH and corneal resistance factor (CRF can discriminate between keratoconus and normal eyes and to evaluate whether the averages of two consecutive measurements perform differently from the one with the best waveform score (WS for diagnosing keratoconus. METHODS: ORA measurements for one eye per individual were selected randomly from 53 normal patients and from 27 patients with keratoconus. Two groups were considered the average (CH-Avg, CRF-Avg and best waveform score (CH-WS, CRF-WS groups. The Mann-Whitney U-test was used to evaluate whether the variables had similar distributions in the Normal and Keratoconus groups. Receiver operating characteristics (ROC curves were calculated for each parameter to assess the efficacy for diagnosing keratoconus and the same obtained for each variable were compared pairwise using the Hanley-McNeil test. RESULTS: The CH-Avg, CRF-Avg, CH-WS and CRF-WS differed significantly between the normal and keratoconus groups (p<0.001. The areas under the ROC curve (AUROC for CH-Avg, CRF-Avg, CH-WS, and CRF-WS were 0.824, 0.873, 0.891, and 0.931, respectively. CH-WS and CRF-WS had significantly better AUROCs than CH-Avg and CRF-Avg, respectively (p=0.001 and 0.002. CONCLUSION: The analysis of the biomechanical properties of the cornea through the ORA method has proved to be an important aid in the diagnosis of keratoconus, regardless of the method used. The best waveform score (WS measurements were superior to the average of consecutive ORA measurements for diagnosing keratoconus.
11. Nonlinear waves in electron–positron–ion plasmas including charge ...
The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are ...
12. Early Cambrian wave-formed shoreline deposits
DEFF Research Database (Denmark)
Clemmensen, Lars B; Glad, Aslaug Clemmensen; Pedersen, Gunver Krarup
2017-01-01
-preserved subaqueous dunes and wave ripples indicates deposition in a wave-dominated upper shoreface (littoral zone) environment, and the presence of interference ripples indicates that the littoral zone environment experienced water level fluctuations due to tides and/or changing meteorological conditions. Discoidal....... During this period, wave-formed shoreline sediments (the Vik Member, Hardeberga Formation) were deposited on Bornholm and are presently exposed at Strøby quarry. The sediments consist of fine- and medium-grained quartz-cemented arenites in association with a few silt-rich mudstones. The presence of well...
13. Waveform design for wireless power transfer
OpenAIRE
Clerckx, B; Bayguzina, E
2016-01-01
Far-field Wireless Power Transfer (WPT) has attracted significant attention in recent years. Despite the rapid progress, the emphasis of the research community in the last decade has remained largely concentrated on improving the design of energy harvester (so-called rectenna) and has left aside the effect of transmitter design. In this paper, we study the design of transmit waveform so as to enhance the DC power at the output of the rectenna. We derive a tractable model of the non-linearity ...
Science.gov (United States)
2016-11-01
the famous Woodward quote, having a ubiquitous feeling for all radar waveform design (and performance prediction) researchers , that is found at the end...discuss research that develops performance prediction models to quantify the impact on SINR when an amplitude constraint is placed on a radar waveform...optimize the radar perfor- mance for the particular scenario and tasks. There have also been several survey papers on various topics in waveform design for
15. On the accuracy and precision of numerical waveforms: effect of waveform extraction methodology
Science.gov (United States)
Chu, Tony; Fong, Heather; Kumar, Prayush; Pfeiffer, Harald P.; Boyle, Michael; Hemberger, Daniel A.; Kidder, Lawrence E.; Scheel, Mark A.; Szilagyi, Bela
2016-08-01
We present a new set of 95 numerical relativity simulations of non-precessing binary black holes (BBHs). The simulations sample comprehensively both black-hole spins up to spin magnitude of 0.9, and cover mass ratios 1-3. The simulations cover on average 24 inspiral orbits, plus merger and ringdown, with low initial orbital eccentricities e\\lt {10}-4. A subset of the simulations extends the coverage of non-spinning BBHs up to mass ratio q = 10. Gravitational waveforms at asymptotic infinity are computed with two independent techniques: extrapolation and Cauchy characteristic extraction. An error analysis based on noise-weighted inner products is performed. We find that numerical truncation error, error due to gravitational wave extraction, and errors due to the Fourier transformation of signals with finite length of the numerical waveforms are of similar magnitude, with gravitational wave extraction errors dominating at noise-weighted mismatches of ˜ 3× {10}-4. This set of waveforms will serve to validate and improve aligned-spin waveform models for gravitational wave science.
16. Advances in waveform-agile sensing for tracking
CERN Document Server
2009-01-01
Recent advances in sensor technology and information processing afford a new flexibility in the design of waveforms for agile sensing. Sensors are now developed with the ability to dynamically choose their transmit or receive waveforms in order to optimize an objective cost function. This has exposed a new paradigm of significant performance improvements in active sensing: dynamic waveform adaptation to environment conditions, target structures, or information features. The manuscript provides a review of recent advances in waveform-agile sensing for target tracking applications. A dynamic wav
17. Wavelet-Based Signal Processing of Electromagnetic Pulse Generated Waveforms
National Research Council Canada - National Science Library
Ardolino, Richard S
2007-01-01
This thesis investigated and compared alternative signal processing techniques that used wavelet-based methods instead of traditional frequency domain methods for processing measured electromagnetic pulse (EMP) waveforms...
18. Ion colliders
International Nuclear Information System (INIS)
Fischer, W.
2010-01-01
Ion colliders are research tools for high-energy nuclear physics, and are used to test the theory of Quantum Chromo Dynamics (QCD). The collisions of fully stripped high-energy ions create matter of a temperature and density that existed only microseconds after the Big Bang. Ion colliders can reach higher densities and temperatures than fixed target experiments although at a much lower luminosity. The first ion collider was the CERN Intersecting Storage Ring (ISR), which collided light ions (77Asb1, 81Bou1). The BNL Relativistic Heavy Ion Collider (RHIC) is in operation since 2000 and has collided a number of species at numerous energies. The CERN Large Hadron Collider (LHC) started the heavy ion program in 2010. Table 1 shows all previous and the currently planned running modes for ISR, RHIC, and LHC. All three machines also collide protons, which are spin-polarized in RHIC. Ion colliders differ from proton or antiproton colliders in a number of ways: the preparation of the ions in the source and the pre-injector chain is limited by other effects than for protons; frequent changes in the collision energy and particle species, including asymmetric species, are typical; and the interaction of ions with each other and accelerator components is different from protons, which has implications for collision products, collimation, the beam dump, and intercepting instrumentation devices such a profile monitors. In the preparation for the collider use the charge state Z of the ions is successively increased to minimize the effects of space charge, intrabeam scattering (IBS), charge change effects (electron capture and stripping), and ion-impact desorption after beam loss. Low charge states reduce space charge, intrabeam scattering, and electron capture effects. High charge states reduce electron stripping, and make bending and acceleration more effective. Electron stripping at higher energies is generally more efficient. Table 2 shows the charge states and energies in the
19. Ion colliders
Energy Technology Data Exchange (ETDEWEB)
Fischer, W.
2011-12-01
Ion colliders are research tools for high-energy nuclear physics, and are used to test the theory of Quantum Chromo Dynamics (QCD). The collisions of fully stripped high-energy ions create matter of a temperature and density that existed only microseconds after the Big Bang. Ion colliders can reach higher densities and temperatures than fixed target experiments although at a much lower luminosity. The first ion collider was the CERN Intersecting Storage Ring (ISR), which collided light ions [77Asb1, 81Bou1]. The BNL Relativistic Heavy Ion Collider (RHIC) is in operation since 2000 and has collided a number of species at numerous energies. The CERN Large Hadron Collider (LHC) started the heavy ion program in 2010. Table 1 shows all previous and the currently planned running modes for ISR, RHIC, and LHC. All three machines also collide protons, which are spin-polarized in RHIC. Ion colliders differ from proton or antiproton colliders in a number of ways: the preparation of the ions in the source and the pre-injector chain is limited by other effects than for protons; frequent changes in the collision energy and particle species, including asymmetric species, are typical; and the interaction of ions with each other and accelerator components is different from protons, which has implications for collision products, collimation, the beam dump, and intercepting instrumentation devices such a profile monitors. In the preparation for the collider use the charge state Z of the ions is successively increased to minimize the effects of space charge, intrabeam scattering (IBS), charge change effects (electron capture and stripping), and ion-impact desorption after beam loss. Low charge states reduce space charge, intrabeam scattering, and electron capture effects. High charge states reduce electron stripping, and make bending and acceleration more effective. Electron stripping at higher energies is generally more efficient. Table 2 shows the charge states and energies in the
20. Elastic reflection waveform inversion with variable density
KAUST Repository
Li, Yuanyuan
2017-08-17
Elastic full waveform inversion (FWI) provides a better description of the subsurface than those given by the acoustic assumption. However it suffers from a more serious cycle skipping problem compared with the latter. Reflection waveform inversion (RWI) provides a method to build a good background model, which can serve as an initial model for elastic FWI. Therefore, we introduce the concept of RWI for elastic media, and propose elastic RWI with variable density. We apply Born modeling to generate the synthetic reflection data by using optimized perturbations of P- and S-wave velocities and density. The inversion for the perturbations in P- and S-wave velocities and density is similar to elastic least-squares reverse time migration (LSRTM). An incorrect initial model will lead to some misfits at the far offsets of reflections; thus, can be utilized to update the background velocity. We optimize the perturbation and background models in a nested approach. Numerical tests on the Marmousi model demonstrate that our method is able to build reasonably good background models for elastic FWI with absence of low frequencies, and it can deal with the variable density, which is needed in real cases.
1. ASYMMETRIC MAGNETIC RECONNECTION IN WEAKLY IONIZED CHROMOSPHERIC PLASMAS
International Nuclear Information System (INIS)
Murphy, Nicholas A.; Lukin, Vyacheslav S.
2015-01-01
Realistic models of magnetic reconnection in the solar chromosphere must take into account that the plasma is partially ionized and that plasma conditions within any two magnetic flux bundles undergoing reconnection may not be the same. Asymmetric reconnection in the chromosphere may occur when newly emerged flux interacts with pre-existing, overlying flux. We present 2.5D simulations of asymmetric reconnection in weakly ionized, reacting plasmas where the magnetic field strengths, ion and neutral densities, and temperatures are different in each upstream region. The plasma and neutral components are evolved separately to allow non-equilibrium ionization. As in previous simulations of chromospheric reconnection, the current sheet thins to the scale of the neutral–ion mean free path and the ion and neutral outflows are strongly coupled. However, the ion and neutral inflows are asymmetrically decoupled. In cases with magnetic asymmetry, a net flow of neutrals through the current sheet from the weak-field (high-density) upstream region into the strong-field upstream region results from a neutral pressure gradient. Consequently, neutrals dragged along with the outflow are more likely to originate from the weak-field region. The Hall effect leads to the development of a characteristic quadrupole magnetic field modified by asymmetry, but the X-point geometry expected during Hall reconnection does not occur. All simulations show the development of plasmoids after an initial laminar phase
2. Force on an Asymmetric Capacitor
National Research Council Canada - National Science Library
Bahder, Thomas
2003-01-01
.... At present, the physical basis for the Biefeld-Brown effect is not understood. The order of magnitude of the net force on the asymmetric capacitor is estimated assuming two different mechanisms of charge conduction between its electrodes...
3. Asymmetric cation-binding catalysis
DEFF Research Database (Denmark)
Oliveira, Maria Teresa; Lee, Jiwoong
2017-01-01
The employment of metal salts is quite limited in asymmetric catalysis, although it would provide an additional arsenal of safe and inexpensive reagents to create molecular functions with high optical purity. Cation chelation by polyethers increases the salts' solubility in conventional organic...... solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...... highly enantioselective silylation reactions in polyether-generated chiral environments, and leading to a record-high turnover in asymmetric organocatalysis. This can lead to further applications by the asymmetric use of other inorganic salts in various organic transformations....
4. Gas-Phase Enrichment of Multiply Charged Peptide Ions by Differential Ion Mobility Extend the Comprehensiveness of SUMO Proteome Analyses
Science.gov (United States)
Pfammatter, Sibylle; Bonneil, Eric; McManus, Francis P.; Thibault, Pierre
2018-04-01
The small ubiquitin-like modifier (SUMO) is a member of the family of ubiquitin-like modifiers (UBLs) and is involved in important cellular processes, including DNA damage response, meiosis and cellular trafficking. The large-scale identification of SUMO peptides in a site-specific manner is challenging not only because of the low abundance and dynamic nature of this modification, but also due to the branched structure of the corresponding peptides that further complicate their identification using conventional search engines. Here, we exploited the unusual structure of SUMO peptides to facilitate their separation by high-field asymmetric waveform ion mobility spectrometry (FAIMS) and increase the coverage of SUMO proteome analysis. Upon trypsin digestion, branched peptides contain a SUMO remnant side chain and predominantly form triply protonated ions that facilitate their gas-phase separation using FAIMS. We evaluated the mobility characteristics of synthetic SUMO peptides and further demonstrated the application of FAIMS to profile the changes in protein SUMOylation of HEK293 cells following heat shock, a condition known to affect this modification. FAIMS typically provided a 10-fold improvement of detection limit of SUMO peptides, and enabled a 36% increase in SUMO proteome coverage compared to the same LC-MS/MS analyses performed without FAIMS. [Figure not available: see fulltext.
5. Multicatalyst system in asymmetric catalysis
CERN Document Server
Zhou, Jian
2014-01-01
This book introduces multi-catalyst systems by describing their mechanism and advantages in asymmetric catalysis. Helps organic chemists perform more efficient catalysis with step-by-step methods Overviews new concepts and progress for greener and economic catalytic reactions Covers topics of interest in asymmetric catalysis including bifunctional catalysis, cooperative catalysis, multimetallic catalysis, and novel tandem reactions Has applications for pharmaceuticals, agrochemicals, materials, and flavour and fragrance
6. Method and apparatus for resonant frequency waveform modulation
Science.gov (United States)
Taubman, Matthew S [Richland, WA
2011-06-07
A resonant modulator device and process are described that provide enhanced resonant frequency waveforms to electrical devices including, e.g., laser devices. Faster, larger, and more complex modulation waveforms are obtained than can be obtained by use of conventional current controllers alone.
7. Frequency-domain waveform inversion using the unwrapped phase
KAUST Repository
Choi, Yun Seok; Alkhalifah, Tariq Ali
2011-01-01
Phase wrapping in the frequency-domain (or cycle skipping in the time-domain) is the major cause of the local minima problem in the waveform inversion. The unwrapped phase has the potential to provide us with a robust and reliable waveform inversion
8. An Overview of Radar Waveform Optimization for Target Detection
Directory of Open Access Journals (Sweden)
Wang Lulu
2016-10-01
Full Text Available An optimal waveform design method that fully employs the knowledge of the target and the environment can further improve target detection performance, thus is of vital importance to research. In this paper, methods of radar waveform optimization for target detection are reviewed and summarized and provide the basis for the research.
9. A pulse generator of arbitrary shaped waveform
International Nuclear Information System (INIS)
Jiang Jiayou; Chen Zhihao
2011-01-01
The three bump magnets in the booster extraction system of SSRF are driven by a signal generator with an external trigger. The signal generator must have three independent and controllable outputs, and both amplitude and make-and-break should be controllable, with current state information being readable. In this paper, we describe a signal generator based on FPGA and DAC boards. It makes use of characteristics of both FPGA flex programmable and rich reconfigurable IO resources. The system has a 16-bit DAC with four outputs, using Matlab to write a GUI based on RS232 protocol for control. It was simulated in Modelsim and tested on board. The results indicate that the system is well designed and all the requirements are met. The arbitrary waveform is writable, and the pulse width and period can be controlled. (authors)
10. Facies Constrained Elastic Full Waveform Inversion
KAUST Repository
Zhang, Z.
2017-05-26
Current efforts to utilize full waveform inversion (FWI) as a tool beyond acoustic imaging applications, for example for reservoir analysis, face inherent limitations on resolution and also on the potential trade-off between elastic model parameters. Adding rock physics constraints does help to mitigate these issues. However, current approaches to add such constraints are based on averaged type rock physics regularization terms. Since the true earth model consists of different facies, averaging over those facies naturally leads to smoothed models. To overcome this, we propose a novel way to utilize facies based constraints in elastic FWI. A so-called confidence map is calculated and updated at each iteration of the inversion using both the inverted models and the prior information. The numerical example shows that the proposed method can reduce the cross-talks and also can improve the resolution of inverted elastic properties.
11. Facies Constrained Elastic Full Waveform Inversion
KAUST Repository
Zhang, Z.; Zabihi Naeini, E.; Alkhalifah, Tariq Ali
2017-01-01
Current efforts to utilize full waveform inversion (FWI) as a tool beyond acoustic imaging applications, for example for reservoir analysis, face inherent limitations on resolution and also on the potential trade-off between elastic model parameters. Adding rock physics constraints does help to mitigate these issues. However, current approaches to add such constraints are based on averaged type rock physics regularization terms. Since the true earth model consists of different facies, averaging over those facies naturally leads to smoothed models. To overcome this, we propose a novel way to utilize facies based constraints in elastic FWI. A so-called confidence map is calculated and updated at each iteration of the inversion using both the inverted models and the prior information. The numerical example shows that the proposed method can reduce the cross-talks and also can improve the resolution of inverted elastic properties.
12. Rectangular waveform linear transformer driver module design
International Nuclear Information System (INIS)
Zhao Yue; Xie Weiping; Zhou Liangji; Chen Lin
2014-01-01
Linear Transformer Driver is a novel pulsed power technology, its main merits include a parallel LC discharge array and Inductive Voltage Adder. The parallel LC discharge array lowers the whole circuit equivalent inductance and the Inductive Voltage Adder unites the modules in series in order to create a high electric field grads, meanwhile, restricts the high voltage in a small space. The lower inductance in favor of LTD output a fast waveform and IVA confine high voltage in secondary cavity. In recently, some LTD-based pulsed power system has been development yet. The usual LTD architecture provides damped sine shaped output pulses that may not be suitable in flash radiography, high power microwave production, z-pinch drivers, and certain other applications. A more suitable driver output pulse would have a flat or inclined top (slightly rising or falling). In this paper, we present the design of an LTD cavity that generates this type of the output pulse by including within its circular array some number of the harmonic bricks in addition to the standard bricks according to Fourier progression theory. The parallel LC discharge array circuit formula is introduced by Kirchhoff Law, and the sum of harmonic is proofed as an analytic result, meanwhile, rationality of design is proved by simulation. Varying gas spark discharge dynamic resistance with harmonic order and switches jitter are analyzed. The results are as following: The more harmonic order is an approach to the ideal rectangular waveform, but lead to more system complexity. The capacity decreases as harmonic order increase, and gas spark discharge dynamic resistance rises with the capacity. The rising time protracts and flat is decay or even vanishes and the shot to shot reproducibility is degenerate as the switches jitter is high. (authors)
13. Synthetic tsunami waveform catalogs with kinematic constraints
Science.gov (United States)
Baptista, Maria Ana; Miranda, Jorge Miguel; Matias, Luis; Omira, Rachid
2017-07-01
In this study we present a comprehensive methodology to produce a synthetic tsunami waveform catalogue in the northeast Atlantic, east of the Azores islands. The method uses a synthetic earthquake catalogue compatible with plate kinematic constraints of the area. We use it to assess the tsunami hazard from the transcurrent boundary located between Iberia and the Azores, whose western part is known as the Gloria Fault. This study focuses only on earthquake-generated tsunamis. Moreover, we assume that the time and space distribution of the seismic events is known. To do this, we compute a synthetic earthquake catalogue including all fault parameters needed to characterize the seafloor deformation covering the time span of 20 000 years, which we consider long enough to ensure the representability of earthquake generation on this segment of the plate boundary. The computed time and space rupture distributions are made compatible with global kinematic plate models. We use the tsunami empirical Green's functions to efficiently compute the synthetic tsunami waveforms for the dataset of coastal locations, thus providing the basis for tsunami impact characterization. We present the results in the form of offshore wave heights for all coastal points in the dataset. Our results focus on the northeast Atlantic basin, showing that earthquake-induced tsunamis in the transcurrent segment of the Azores-Gibraltar plate boundary pose a minor threat to coastal areas north of Portugal and beyond the Strait of Gibraltar. However, in Morocco, the Azores, and the Madeira islands, we can expect wave heights between 0.6 and 0.8 m, leading to precautionary evacuation of coastal areas. The advantages of the method are its easy application to other regions and the low computation effort needed.
14. Design of a 9-loop quasi-exponential waveform generator.
Science.gov (United States)
Banerjee, Partha; Shukla, Rohit; Shyam, Anurag
2015-12-01
We know in an under-damped L-C-R series circuit, current follows a damped sinusoidal waveform. But if a number of sinusoidal waveforms of decreasing time period, generated in an L-C-R circuit, be combined in first quarter cycle of time period, then a quasi-exponential nature of output current waveform can be achieved. In an L-C-R series circuit, quasi-exponential current waveform shows a rising current derivative and thereby finds many applications in pulsed power. Here, we have described design and experiment details of a 9-loop quasi-exponential waveform generator. In that, design details of magnetic switches have also been described. In the experiment, output current of 26 kA has been achieved. It has been shown that how well the experimentally obtained output current profile matches with the numerically computed output.
15. Asymmetric Gepner models (revisited)
Energy Technology Data Exchange (ETDEWEB)
Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands)] [Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: [email protected] [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands)] [Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain)] [IMAPP, Radboud Universiteit, Nijmegen (Netherlands)
2010-12-11
We reconsider a class of heterotic string theories studied in 1989, based on tensor products of N=2 minimal models with asymmetric simple current invariants. We extend this analysis from (2,2) and (1,2) spectra to (0,2) spectra with SO(10) broken to the Standard Model. In the latter case the spectrum must contain fractionally charged particles. We find that in nearly all cases at least some of them are massless. However, we identify a large subclass where the fractional charges are at worst half-integer, and often vector-like. The number of families is very often reduced in comparison to the 1989 results, but there are no new tensor combinations yielding three families. All tensor combinations turn out to fall into two classes: those where the number of families is always divisible by three, and those where it is never divisible by three. We find an empirical rule to determine the class, which appears to extend beyond minimal N=2 tensor products. We observe that distributions of physical quantities such as the number of families, singlets and mirrors have an interesting tendency towards smaller values as the gauge groups approaches the Standard Model. We compare our results with an analogous class of free fermionic models. This displays similar features, but with less resolution. Finally we present a complete scan of the three family models based on the triply-exceptional combination (1,16{sup *},16{sup *},16{sup *}) identified originally by Gepner. We find 1220 distinct three family spectra in this case, forming 610 mirror pairs. About half of them have the gauge group SU(3)xSU(2){sub L}xSU(2){sub R}xU(1){sup 5}, the theoretical minimum, and many others are trinification models.
16. Ionization asymmetry effects on the properties modulation of atmospheric pressure dielectric barrier discharge sustained by tailored voltage waveforms
Science.gov (United States)
Zhang, Z. L.; Nie, Q. Y.; Zhang, X. N.; Wang, Z. B.; Kong, F. R.; Jiang, B. H.; Lim, J. W. M.
2018-04-01
The dielectric barrier discharge (DBD) is a promising technology to generate high density and uniform cold plasmas in atmospheric pressure gases. The effective independent tuning of key plasma parameters is quite important for both application-focused and fundamental studies. In this paper, based on a one-dimensional fluid model with semi-kinetics treatment, numerical studies of ionization asymmetry effects on the properties modulation of atmospheric DBD sustained by tailored voltage waveforms are reported. The driving voltage waveform is characterized by an asymmetric-slope fundamental sinusoidal radio frequency signal superimposing one or more harmonics, and the effects of the number of harmonics, phase shift, as well as the fluctuation of harmonics on the sheath dynamics, impact ionization of electrons and key plasma parameters are investigated. The results have shown that the electron density can exhibit a substantial increase due to the effective electron heating by a spatially asymmetric sheath structure. The strategic modulation of harmonics number and phase shift is capable of raising the electron density significantly (e.g., nearly three times in this case), but without a significant increase in the gas temperature. Moreover, by tailoring the fluctuation of harmonics with a steeper slope, a more profound efficiency in electron impact ionization can be achieved, and thus enhancing the electron density effectively. This method then enables a novel alternative approach to realize the independent control of the key plasma parameters under atmospheric pressure.
17. Closed form of optimal current waveform for class-F PA up to fourth ...
PA and its dual, usually referred as inverse class-F PA, current and voltage ... voltage waveforms provides a number of advantages in the process of PA design ... RF PA design approaches with waveform theory and experimental waveform.
18. Gradient pre-emphasis to counteract first-order concomitant fields on asymmetric MRI gradient systems.
Science.gov (United States)
Tao, Shengzhen; Weavers, Paul T; Trzasko, Joshua D; Shu, Yunhong; Huston, John; Lee, Seung-Kyun; Frigo, Louis M; Bernstein, Matt A
2017-06-01
19. D mesons in asymmetric nuclear matter
International Nuclear Information System (INIS)
Mishra, Amruta; Mazumdar, Arindam
2009-01-01
We calculate the in-medium D and D meson masses in isospin-asymmetric nuclear matter in an effective chiral model. The D and D mass modifications arising from their interactions with the nucleons and the scalar mesons in the effective hadronic model are seen to be appreciable at high densities and have a strong isospin dependence. These mass modifications can open the channels of the decay of the charmonium states (Ψ ' ,χ c ,J/Ψ) to DD pairs in dense hadronic matter. The isospin asymmetry in the doublet D=(D 0 ,D + ) is seen to be particularly appreciable at high densities and should show in observables such as their production and flow in asymmetric heavy-ion collisions in the compressed baryonic matter experiments in the future facility of FAIR, GSI. The results of the present work are compared to calculations of the D(D) in-medium masses in the literature using the QCD sum rule approach, quark meson coupling model, and coupled channel approach as well as to those from studies of quarkonium dissociation using heavy-quark potentials from lattice QCD at finite temperatures
20. Waveform analysis of tremor may help to differentiate Parkinson's disease from drug-induced parkinsonism
International Nuclear Information System (INIS)
Jang, W; Han, J; Kim, I Y; Park, J; Kim, J-S; Cho, J W; Koh, S-B; Chung, S J; Kim, H-T
2013-01-01
In this study, we analyzed the waveform characteristics of resting tremor by accelerometer recordings in patients with drug-induced parkinsonism (DIP) and Parkinson's disease (PD). We prospectively recruited 12 patients with tremulous PD and 12 patients with DIP presenting with resting tremor. Tremor was recorded from the more affected side and was recorded twice for a 60 s period in each patient. Peak frequency, amplitude and all harmonic peaks were obtained, and the asymmetry of the decay of the autocorrelation function, third momentum and time-reversal invariance were also computed using a mathematical algorithm. Among the parameters used in the waveform analysis, the harmonic ratio, time-reversal invariance and asymmetric decay of the autocorrelation function were different between PD and DIP at a statistically significant level (all p < 0.01). The total harmonic peak power and third momentum in the time series were not significantly different. The clinical characteristics of DIP patients may be similar to those of PD patients in some cases, which makes the clinical differentiation between DIP and PD challenging. Our study shows that the identification of parameters reflecting waveform asymmetry might be helpful in differentiating between DIP and PD. (note)
1. A piezoelectric micro control valve with integrated capacitive sensing for ambulant blood pressure waveform monitoring
Science.gov (United States)
Groen, Maarten S.; Wu, Kai; Brookhuis, Robert A.; van Houwelingen, Marc J.; Brouwer, Dannis M.; Lötters, Joost C.; Wiegerink, Remco J.
2014-12-01
We have designed and characterized a MEMS microvalve with built-in capacitive displacement sensing and fitted it with a miniature piezoelectric actuator to achieve active valve control. The integrated displacement sensor enables high bandwidth proportional control of the gas flow through the valve. This is an essential requirement for non-invasive blood pressure waveform monitoring based on following the arterial pressure with a counter pressure. Using the capacitive sensor, we demonstrate negligible hysteresis in the valve control characteristics. Fabrication of the valve requires only two mask steps for deep reactive ion etching (DRIE) and one release etch.
2. A piezoelectric micro control valve with integrated capacitive sensing for ambulant blood pressure waveform monitoring
International Nuclear Information System (INIS)
Groen, Maarten S; Wu, Kai; Brookhuis, Robert A; Lötters, Joost C; Wiegerink, Remco J; Van Houwelingen, Marc J; Brouwer, Dannis M
2014-01-01
We have designed and characterized a MEMS microvalve with built-in capacitive displacement sensing and fitted it with a miniature piezoelectric actuator to achieve active valve control. The integrated displacement sensor enables high bandwidth proportional control of the gas flow through the valve. This is an essential requirement for non-invasive blood pressure waveform monitoring based on following the arterial pressure with a counter pressure. Using the capacitive sensor, we demonstrate negligible hysteresis in the valve control characteristics. Fabrication of the valve requires only two mask steps for deep reactive ion etching (DRIE) and one release etch. (paper)
3. Fast Prediction and Evaluation of Gravitational Waveforms Using Surrogate Models
Science.gov (United States)
Field, Scott E.; Galley, Chad R.; Hesthaven, Jan S.; Kaye, Jason; Tiglio, Manuel
2014-07-01
We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced order model in both parameter and physical dimensions that can be used as a surrogate for the true or fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant that is built for the fiducial waveform family. Third, a fit in the parameter dimension is performed for the waveform's value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order O(mL+mcfit) online operations, where cfit denotes the fitting function operation count and, typically, m ≪L. The result is a compact, computationally efficient, and accurate surrogate model that retains the original physics of the fiducial waveform family while also being fast to evaluate. We generate accurate surrogate models for effective-one-body waveforms of nonspinning binary black hole coalescences with durations as long as 105M, mass ratios from 1 to 10, and for multiple spherical harmonic modes. We find that these surrogates are more than 3 orders of magnitude faster to evaluate as compared to the cost of generating effective-one-body waveforms in standard ways. Surrogate model building for other waveform families and models follows the same steps and has the same low computational online scaling cost. For expensive numerical simulations of binary black hole coalescences, we thus anticipate extremely large speedups in generating new waveforms with a
4. Asymmetric double Langmuir probe: Small signal application
International Nuclear Information System (INIS)
Uckan, T.
1987-11-01
We discuss the asymmetric double Langmuir probe (ADLP) and demonstrate the possibility of using it to measure plasma temperature T/sub e/ and density n when it is operated in the region of small signal response. The area of one of the ADLP collectors is considerably larger than the other. This probe can be operated at a relatively low applied voltage, eV/sub a/T/sub e/ < 1, and still provides sufficient information to determine the plasma T/sub e/ and n. There is no need for a direct measurement of the ion saturation current, which can be on the order of a few amperes in large fusion devices. This reduces the requirements on the probe power supply. 6 refs., 6 figs
5. Isospin dependent properties of asymmetric nuclear matter
Science.gov (United States)
Chowdhury, P. Roy; Basu, D. N.; Samanta, C.
2009-07-01
The density dependence of nuclear symmetry energy is determined from a systematic study of the isospin dependent bulk properties of asymmetric nuclear matter using the isoscalar and isovector components of the density dependent M3Y interaction. The incompressibility K∞ for the symmetric nuclear matter, the isospin dependent part Kasy of the isobaric incompressibility, and the slope L are all in excellent agreement with the constraints recently extracted from measured isotopic dependence of the giant monopole resonances in even-A Sn isotopes, from the neutron skin thickness of nuclei, and from analyses of experimental data on isospin diffusion and isotopic scaling in intermediate energy heavy-ion collisions. This work provides a fundamental basis for the understanding of nuclear matter under extreme conditions and validates the important empirical constraints obtained from recent experimental data.
6. Electrochemical sensing using comparison of voltage-current time differential values during waveform generation and detection
Science.gov (United States)
Woo, Leta Yar-Li; Glass, Robert Scott; Fitzpatrick, Joseph Jay; Wang, Gangqiang; Henderson, Brett Tamatea; Lourdhusamy, Anthoniraj; Steppan, James John; Allmendinger, Klaus Karl
2018-01-02
A device for signal processing. The device includes a signal generator, a signal detector, and a processor. The signal generator generates an original waveform. The signal detector detects an affected waveform. The processor is coupled to the signal detector. The processor receives the affected waveform from the signal detector. The processor also compares at least one portion of the affected waveform with the original waveform. The processor also determines a difference between the affected waveform and the original waveform. The processor also determines a value corresponding to a unique portion of the determined difference between the original and affected waveforms. The processor also outputs the determined value.
7. Source-independent elastic waveform inversion using a logarithmic wavefield
KAUST Repository
Choi, Yun Seok
2012-01-01
The logarithmic waveform inversion has been widely developed and applied to some synthetic and real data. In most logarithmic waveform inversion algorithms, the subsurface velocities are updated along with the source estimation. To avoid estimating the source wavelet in the logarithmic waveform inversion, we developed a source-independent logarithmic waveform inversion algorithm. In this inversion algorithm, we first normalize the wavefields with the reference wavefield to remove the source wavelet, and then take the logarithm of the normalized wavefields. Based on the properties of the logarithm, we define three types of misfit functions using the following methods: combination of amplitude and phase, amplitude-only, and phase-only. In the inversion, the gradient is computed using the back-propagation formula without directly calculating the Jacobian matrix. We apply our algorithm to noise-free and noise-added synthetic data generated for the modified version of elastic Marmousi2 model, and compare the results with those of the source-estimation logarithmic waveform inversion. For the noise-free data, the source-independent algorithms yield velocity models close to true velocity models. For random-noise data, the source-estimation logarithmic waveform inversion yields better results than the source-independent method, whereas for coherent-noise data, the results are reversed. Numerical results show that the source-independent and source-estimation logarithmic waveform inversion methods have their own merits for random- and coherent-noise data. © 2011.
8. Generation of correlated finite alphabet waveforms using gaussian random variables
KAUST Repository
Jardak, Seifallah
2014-09-01
Correlated waveforms have a number of applications in different fields, such as radar and communication. It is very easy to generate correlated waveforms using infinite alphabets, but for some of the applications, it is very challenging to use them in practice. Moreover, to generate infinite alphabet constant envelope correlated waveforms, the available research uses iterative algorithms, which are computationally very expensive. In this work, we propose simple novel methods to generate correlated waveforms using finite alphabet constant and non-constant-envelope symbols. To generate finite alphabet waveforms, the proposed method map the Gaussian random variables onto the phase-shift-keying, pulse-amplitude, and quadrature-amplitude modulation schemes. For such mapping, the probability-density-function of Gaussian random variables is divided into M regions, where M is the number of alphabets in the corresponding modulation scheme. By exploiting the mapping function, the relationship between the cross-correlation of Gaussian and finite alphabet symbols is derived. To generate equiprobable symbols, the area of each region is kept same. If the requirement is to have each symbol with its own unique probability, the proposed scheme allows us that as well. Although, the proposed scheme is general, the main focus of this paper is to generate finite alphabet waveforms for multiple-input multiple-output radar, where correlated waveforms are used to achieve desired beampatterns. © 2014 IEEE.
9. Waveform LiDAR across forest biomass gradients
Science.gov (United States)
Montesano, P. M.; Nelson, R. F.; Dubayah, R.; Sun, G.; Ranson, J.
2011-12-01
Detailed information on the quantity and distribution of aboveground biomass (AGB) is needed to understand how it varies across space and changes over time. Waveform LiDAR data is routinely used to derive the heights of scattering elements in each illuminated footprint, and the vertical structure of vegetation is related to AGB. Changes in LiDAR waveforms across vegetation structure gradients can demonstrate instrument sensitivity to land cover transitions. A close examination of LiDAR waveforms in footprints across a forest gradient can provide new insight into the relationship of vegetation structure and forest AGB. In this study we use field measurements of individual trees within Laser Vegetation Imaging Sensor (LVIS) footprints along transects crossing forest to non-forest gradients to examine changes in LVIS waveform characteristics at sites with low (field AGB measurements to original and adjusted LVIS waveforms to detect the forest AGB interval along a forest - non-forest transition in which the LVIS waveform lose the ability to discern differences in AGB. Our results help identify the lower end the forest biomass range that a ~20m footprint waveform LiDAR can detect, which can help infer accumulation of biomass after disturbances and during forest expansion, and which can guide the use of LiDAR within a multi-sensor fusion biomass mapping approach.
10. SURFACE FITTING FILTERING OF LIDAR POINT CLOUD WITH WAVEFORM INFORMATION
Directory of Open Access Journals (Sweden)
S. Xing
2017-09-01
Full Text Available Full-waveform LiDAR is an active technology of photogrammetry and remote sensing. It provides more detailed information about objects along the path of a laser pulse than discrete-return topographic LiDAR. The point cloud and waveform information with high quality can be obtained by waveform decomposition, which could make contributions to accurate filtering. The surface fitting filtering method with waveform information is proposed to present such advantage. Firstly, discrete point cloud and waveform parameters are resolved by global convergent Levenberg Marquardt decomposition. Secondly, the ground seed points are selected, of which the abnormal ones are detected by waveform parameters and robust estimation. Thirdly, the terrain surface is fitted and the height difference threshold is determined in consideration of window size and mean square error. Finally, the points are classified gradually with the rising of window size. The filtering process is finished until window size is larger than threshold. The waveform data in urban, farmland and mountain areas from “WATER (Watershed Allied Telemetry Experimental Research” are selected for experiments. Results prove that compared with traditional method, the accuracy of point cloud filtering is further improved and the proposed method has highly practical value.
11. High Current Ionic Diode Using Homogeneously Charged Asymmetric Nanochannel Network Membrane.
Science.gov (United States)
Choi, Eunpyo; Wang, Cong; Chang, Gyu Tae; Park, Jungyul
2016-04-13
A high current ionic diode is achieved using an asymmetric nanochannel network membrane (NCNM) constructed by soft lithography and in situ self-assembly of nanoparticles with uniform surface charge. The asymmetric NCNM exhibits high rectified currents without losing a rectification ratio because of its ionic selectivity gradient and differentiated electrical conductance. Asymmetric ionic transport is analyzed with diode-like I-V curves and visualized via fluorescent dyes, which is closely correlated with ionic selectivity and ion distribution according to variation of NCNM geometries.
12. Statistical gravitational waveform models: What to simulate next?
Science.gov (United States)
Doctor, Zoheyr; Farr, Ben; Holz, Daniel E.; Pürrer, Michael
2017-12-01
Models of gravitational waveforms play a critical role in detecting and characterizing the gravitational waves (GWs) from compact binary coalescences. Waveforms from numerical relativity (NR), while highly accurate, are too computationally expensive to produce to be directly used with Bayesian parameter estimation tools like Markov-chain-Monte-Carlo and nested sampling. We propose a Gaussian process regression (GPR) method to generate reduced-order-model waveforms based only on existing accurate (e.g. NR) simulations. Using a training set of simulated waveforms, our GPR approach produces interpolated waveforms along with uncertainties across the parameter space. As a proof of concept, we use a training set of IMRPhenomD waveforms to build a GPR model in the 2-d parameter space of mass ratio q and equal-and-aligned spin χ1=χ2. Using a regular, equally-spaced grid of 120 IMRPhenomD training waveforms in q ∈[1 ,3 ] and χ1∈[-0.5 ,0.5 ], the GPR mean approximates IMRPhenomD in this space to mismatches below 4.3 ×10-5. Our approach could in principle use training waveforms directly from numerical relativity. Beyond interpolation of waveforms, we also present a greedy algorithm that utilizes the errors provided by our GPR model to optimize the placement of future simulations. In a fiducial test case we find that using the greedy algorithm to iteratively add simulations achieves GPR errors that are ˜1 order of magnitude lower than the errors from using Latin-hypercube or square training grids.
13. Fast Prediction and Evaluation of Gravitational Waveforms Using Surrogate Models
Directory of Open Access Journals (Sweden)
Scott E. Field
2014-07-01
Full Text Available We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced order model in both parameter and physical dimensions that can be used as a surrogate for the true or fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant that is built for the fiducial waveform family. Third, a fit in the parameter dimension is performed for the waveform’s value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order O(mL+mc_{fit} online operations, where c_{fit} denotes the fitting function operation count and, typically, m≪L. The result is a compact, computationally efficient, and accurate surrogate model that retains the original physics of the fiducial waveform family while also being fast to evaluate. We generate accurate surrogate models for effective-one-body waveforms of nonspinning binary black hole coalescences with durations as long as 10^{5}M, mass ratios from 1 to 10, and for multiple spherical harmonic modes. We find that these surrogates are more than 3 orders of magnitude faster to evaluate as compared to the cost of generating effective-one-body waveforms in standard ways. Surrogate model building for other waveform families and models follows the same steps and has the same low computational online scaling cost. For expensive numerical simulations of binary black hole coalescences, we thus anticipate extremely large speedups in
14. Does asymmetric correlation affect portfolio optimization?
Science.gov (United States)
Fryd, Lukas
2017-07-01
The classical portfolio optimization problem does not assume asymmetric behavior of relationship among asset returns. The existence of asymmetric response in correlation on the bad news could be important information in portfolio optimization. The paper applies Dynamic conditional correlation model (DCC) and his asymmetric version (ADCC) to propose asymmetric behavior of conditional correlation. We analyse asymmetric correlation among S&P index, bonds index and spot gold price before mortgage crisis in 2008. We evaluate forecast ability of the models during and after mortgage crisis and demonstrate the impact of asymmetric correlation on the reduction of portfolio variance.
15. Full Waveform Inversion Using Nonlinearly Smoothed Wavefields
KAUST Repository
Li, Y.; Choi, Yun Seok; Alkhalifah, Tariq Ali; Li, Z.
2017-01-01
The lack of low frequency information in the acquired data makes full waveform inversion (FWI) conditionally converge to the accurate solution. An initial velocity model that results in data with events within a half cycle of their location in the observed data was required to converge. The multiplication of wavefields with slightly different frequencies generates artificial low frequency components. This can be effectively utilized by multiplying the wavefield with itself, which is nonlinear operation, followed by a smoothing operator to extract the artificially produced low frequency information. We construct the objective function using the nonlinearly smoothed wavefields with a global-correlation norm to properly handle the energy imbalance in the nonlinearly smoothed wavefield. Similar to the multi-scale strategy, we progressively reduce the smoothing width applied to the multiplied wavefield to welcome higher resolution. We calculate the gradient of the objective function using the adjoint-state technique, which is similar to the conventional FWI except for the adjoint source. Examples on the Marmousi 2 model demonstrate the feasibility of the proposed FWI method to mitigate the cycle-skipping problem in the case of a lack of low frequency information.
16. Full Waveform Inversion Using Nonlinearly Smoothed Wavefields
KAUST Repository
Li, Y.
2017-05-26
The lack of low frequency information in the acquired data makes full waveform inversion (FWI) conditionally converge to the accurate solution. An initial velocity model that results in data with events within a half cycle of their location in the observed data was required to converge. The multiplication of wavefields with slightly different frequencies generates artificial low frequency components. This can be effectively utilized by multiplying the wavefield with itself, which is nonlinear operation, followed by a smoothing operator to extract the artificially produced low frequency information. We construct the objective function using the nonlinearly smoothed wavefields with a global-correlation norm to properly handle the energy imbalance in the nonlinearly smoothed wavefield. Similar to the multi-scale strategy, we progressively reduce the smoothing width applied to the multiplied wavefield to welcome higher resolution. We calculate the gradient of the objective function using the adjoint-state technique, which is similar to the conventional FWI except for the adjoint source. Examples on the Marmousi 2 model demonstrate the feasibility of the proposed FWI method to mitigate the cycle-skipping problem in the case of a lack of low frequency information.
17. Femtosecond Nanofocusing with Full Optical Waveform Control
International Nuclear Information System (INIS)
Berweger, Samuel; Atkin, Joanna M.; Xu, Xiaoji G.; Olmon, Robert L.; Raschke, Markus Bernd
2011-01-01
The simultaneous nanometer spatial confinement and femtosecond temporal control of an optical excitation has been a long-standing challenge in optics. Previous approaches using surface plasmon polariton (SPP) resonant nanostructures or SPP waveguides have suffered from, for example, mode mismatch, or possible dependence on the phase of the driving laser field to achieve spatial localization. Here we take advantage of the intrinsic phase- and amplitude-independent nanofocusing ability of a conical noble metal tip with weak wavelength dependence over a broad bandwidth to achieve a 10 nm spatially and few-femtosecond temporally confined excitation. In combination with spectral pulse shaping and feedback on the second-harmonic response of the tip apex, we demonstrate deterministic arbitrary optical waveform control. In addition, the high efficiency of the nanofocusing tip provided by the continuous micro- to nanoscale mode transformation opens the door for spectroscopy of elementary optical excitations in matter on their natural length and time scales and enables applications from ultrafast nano-opto-electronics to single molecule quantum coherent control.
18. Full waveform inversion for mechanized tunneling reconnaissance
Science.gov (United States)
Lamert, Andre; Musayev, Khayal; Lambrecht, Lasse; Friederich, Wolfgang; Hackl, Klaus; Baitsch, Matthias
2016-04-01
In mechanized tunnel drilling processes, exploration of soil structure and properties ahead of the tunnel boring machine can greatly help to lower costs and improve safety conditions during drilling. We present numerical full waveform inversion approaches in time and frequency domain of synthetic acoustic data to detect different small scale structures representing potential obstacles in front of the tunnel boring machine. With the use of sensitivity kernels based on the adjoint wave field in time domain and in frequency domain it is possible to derive satisfactory models with a manageable amount of computational load. Convergence to a suitable model is assured by the use of iterative model improvements and gradually increasing frequencies. Results of both, time and frequency approach, will be compared for different obstacle and source/receiver setups. They show that the image quality strongly depends on the used receiver and source positions and increases significantly with the use of transmission waves due to the installed receivers and sources at the surface and/or in bore holes. Transmission waves lead to clearly identified structure and position of the obstacles and give satisfactory guesses for the wave speed. Setups using only reflected waves result in blurred objects and ambiguous position of distant objects and allow to distinguish heterogeneities with higher or lower wave speed, respectively.
19. SeisFlows-Flexible waveform inversion software
Science.gov (United States)
Modrak, Ryan T.; Borisov, Dmitry; Lefebvre, Matthieu; Tromp, Jeroen
2018-06-01
SeisFlows is an open source Python package that provides a customizable waveform inversion workflow and framework for research in oil and gas exploration, earthquake tomography, medical imaging, and other areas. New methods can be rapidly prototyped in SeisFlows by inheriting from default inversion or migration classes, and code can be tested on 2D examples before application to more expensive 3D problems. Wave simulations must be performed using an external software package such as SPECFEM3D. The ability to interface with external solvers lends flexibility, and the choice of SPECFEM3D as a default option provides optional GPU acceleration and other useful capabilities. Through support for massively parallel solvers and interfaces for high-performance computing (HPC) systems, inversions with thousands of seismic traces and billions of model parameters can be performed. So far, SeisFlows has run on clusters managed by the Department of Defense, Chevron Corp., Total S.A., Princeton University, and the University of Alaska, Fairbanks.
20. Asymmetric Synthesis via Chiral Aziridines
DEFF Research Database (Denmark)
Tanner, David Ackland; Harden, Adrian; Wyatt, Paul
1996-01-01
A series of chiral bis(aziridines) has been synthesised and evaluated as chelating ligands for a variety of asymmetric transformations mediated by metals [Os (dihydroxylation), Pd (allylic alkylation) Cu (cyclopropanation and aziridination, Li (1,2-addition of organolithiums to imines)]. In the b......A series of chiral bis(aziridines) has been synthesised and evaluated as chelating ligands for a variety of asymmetric transformations mediated by metals [Os (dihydroxylation), Pd (allylic alkylation) Cu (cyclopropanation and aziridination, Li (1,2-addition of organolithiums to imines...
1. Ideal 3D asymmetric concentrator
Energy Technology Data Exchange (ETDEWEB)
2009-01-15
Nonimaging optics is a field devoted to the design of optical components for applications such as solar concentration or illumination. In this field, many different techniques have been used for producing reflective and refractive optical devices, including reverse engineering techniques. In this paper we apply photometric field theory and elliptic ray bundles method to study 3D asymmetric - without rotational or translational symmetry - concentrators, which can be useful components for nontracking solar applications. We study the one-sheet hyperbolic concentrator and we demonstrate its behaviour as ideal 3D asymmetric concentrator. (author)
2. A Novel wave-form command shaper for overhead cranes
Directory of Open Access Journals (Sweden)
KHALED ALHAZZA
2013-12-01
Full Text Available In this work, a novel command shaping control strategy for oscillation reduction of simple harmonic oscillators is proposed, and validated experimentally. A wave-form acceleration command shaper is derived analytically. The performance of the proposed shaper is simulated numerically, and validated experimentally on a scaled model of an overhead crane. Amplitude modulation is used to enhance the shaper performance, which results in a modulated wave-form command shaper. It is determined that the proposed wave-form and modulated wave-form command shaper profiles are capable of eliminating travel and residual oscillations. Furthermore, unlike traditional impulse and step command shapers, the proposed command shaper has piecewise smoother acceleration, velocity, and displacement profiles. Experimental results using continuous and discrete commands are presented. Experiments with discrete commands involved embedding a saturation model-based feedback in the algorithm of the command shaper.
3. Generation of correlated finite alphabet waveforms using gaussian random variables
KAUST Repository
Ahmed, Sajid
2016-01-13
Various examples of methods and systems are provided for generation of correlated finite alphabet waveforms using Gaussian random variables in, e.g., radar and communication applications. In one example, a method includes mapping an input signal comprising Gaussian random variables (RVs) onto finite-alphabet non-constant-envelope (FANCE) symbols using a predetermined mapping function, and transmitting FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The FANCE waveforms can be based upon the mapping of the Gaussian RVs onto the FANCE symbols. In another example, a system includes a memory unit that can store a plurality of digital bit streams corresponding to FANCE symbols and a front end unit that can transmit FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The system can include a processing unit that can encode the input signal and/or determine the mapping function.
4. Maass waveforms arising from sigma and related indefinite theta functions
OpenAIRE
Zwegers, Sander
2010-01-01
In this paper we consider an example of a Maass waveform which was constructed by Cohen from a function $\\sigma$, studied by Andrews, Dyson and Hickerson, and it's companion $\\sigma^*$. We put this example in a more general framework.
5. Efficient data retrieval method for similar plasma waveforms in EAST
Energy Technology Data Exchange (ETDEWEB)
Liu, Ying, E-mail: [email protected] [SZU-CASIPP Joint Laboratory for Applied Plasma, Shenzhen University, Shenzhen 518060 (China); Huang, Jianjun; Zhou, Huasheng; Wang, Fan [SZU-CASIPP Joint Laboratory for Applied Plasma, Shenzhen University, Shenzhen 518060 (China); Wang, Feng [Institute of Plasma Physics Chinese Academy of Sciences, Hefei 230031 (China)
2016-11-15
Highlights: • The proposed method is carried out by means of bounding envelope and angle distance. • It allows retrieving for whole similar waveforms of any time length. • In addition, the proposed method is also possible to retrieve subsequences. - Abstract: Fusion research relies highly on data analysis due to its massive-sized database. In the present work, we propose an efficient method for searching and retrieving similar plasma waveforms in Experimental Advanced Superconducting Tokamak (EAST). Based on Piecewise Linear Aggregate Approximation (PLAA) for extracting feature values, the searching process is accomplished in two steps. The first one is coarse searching to narrow down the search space, which is carried out by means of bounding envelope. The second step is fine searching to retrieval similar waveforms, which is implemented by the angle distance. The proposed method is tested in EAST databases and turns out to have good performance in retrieving similar waveforms.
6. Conditioning the full-waveform inversion gradient to welcome anisotropy
KAUST Repository
Alkhalifah, Tariq Ali
2015-01-01
Multiparameter full-waveform inversion (FWI) suffers from complex nonlinearity in the objective function, compounded by the eventual trade-off between the model parameters. A hierarchical approach based on frequency and arrival time data decimation
7. Anisotropic wave-equation traveltime and waveform inversion
KAUST Repository
Feng, Shihang; Schuster, Gerard T.
2016-01-01
The wave-equation traveltime and waveform inversion (WTW) methodology is developed to invert for anisotropic parameters in a vertical transverse isotropic (VTI) meidum. The simultaneous inversion of anisotropic parameters v0, ε and δ is initially
8. Full Waveform Inversion Using Oriented Time Migration Method
KAUST Repository
Zhang, Zhendong
2016-01-01
Full waveform inversion (FWI) for reflection events is limited by its linearized update requirements given by a process equivalent to migration. Unless the background velocity model is reasonably accurate the resulting gradient can have
9. Interferometric full-waveform inversion of time-lapse data
KAUST Repository
Sinha, Mrinal
2017-01-01
surveys. To overcome this challenge, we propose the use of interferometric full waveform inversion (IFWI) for inverting the velocity model from data recorded by baseline and monitor surveys. A known reflector is used as the reference reflector for IFWI
10. Velocity Building by Reflection Waveform Inversion without Cycle-skipping
KAUST Repository
Guo, Qiang; Alkhalifah, Tariq Ali; Wu, Zedong
2017-01-01
Reflection waveform inversion (RWI) provides estimation of low wavenumber model components using reflections generated from a migration/demigration process. The resulting model tends to be a good initial model for FWI. In fact, the optimization
11. 3-D waveform tomography sensitivity kernels for anisotropic media
KAUST Repository
Djebbi, Ramzi; Alkhalifah, Tariq Ali
2014-01-01
The complications in anisotropic multi-parameter inversion lie in the trade-off between the different anisotropy parameters. We compute the tomographic waveform sensitivity kernels for a VTI acoustic medium perturbation as a tool to investigate
12. Spectral implementation of full waveform inversion based on reflections
KAUST Repository
Wu, Zedong; Alkhalifah, Tariq Ali
2014-01-01
Using the reflection imaging process as a source to model reflections for full waveform inversion (FWI), referred to as reflection FWI (RFWI), allows us to update the background component of the model, and avoid using the relatively costly migration
13. Solving seismological problems using sgraph program: II-waveform modeling
International Nuclear Information System (INIS)
Abdelwahed, Mohamed F.
2012-01-01
One of the seismological programs to manipulate seismic data is SGRAPH program. It consists of integrated tools to perform advanced seismological techniques. SGRAPH is considered a new system for maintaining and analyze seismic waveform data in a stand-alone Windows-based application that manipulate a wide range of data formats. SGRAPH was described in detail in the first part of this paper. In this part, I discuss the advanced techniques including in the program and its applications in seismology. Because of the numerous tools included in the program, only SGRAPH is sufficient to perform the basic waveform analysis and to solve advanced seismological problems. In the first part of this paper, the application of the source parameters estimation and hypocentral location was given. Here, I discuss SGRAPH waveform modeling tools. This paper exhibits examples of how to apply the SGRAPH tools to perform waveform modeling for estimating the focal mechanism and crustal structure of local earthquakes.
14. Generation of correlated finite alphabet waveforms using gaussian random variables
KAUST Repository
Ahmed, Sajid; Alouini, Mohamed-Slim; Jardak, Seifallah
2016-01-01
Various examples of methods and systems are provided for generation of correlated finite alphabet waveforms using Gaussian random variables in, e.g., radar and communication applications. In one example, a method includes mapping an input signal comprising Gaussian random variables (RVs) onto finite-alphabet non-constant-envelope (FANCE) symbols using a predetermined mapping function, and transmitting FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The FANCE waveforms can be based upon the mapping of the Gaussian RVs onto the FANCE symbols. In another example, a system includes a memory unit that can store a plurality of digital bit streams corresponding to FANCE symbols and a front end unit that can transmit FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The system can include a processing unit that can encode the input signal and/or determine the mapping function.
15. Lane marking detection based on waveform analysis and CNN
Science.gov (United States)
Ye, Yang Yang; Chen, Hou Jin; Hao, Xiao Li
2017-06-01
Lane markings detection is a very important part of the ADAS to avoid traffic accidents. In order to obtain accurate lane markings, in this work, a novel and efficient algorithm is proposed, which analyses the waveform generated from the road image after inverse perspective mapping (IPM). The algorithm includes two main stages: the first stage uses an image preprocessing including a CNN to reduce the background and enhance the lane markings. The second stage obtains the waveform of the road image and analyzes the waveform to get lanes. The contribution of this work is that we introduce local and global features of the waveform to detect the lane markings. The results indicate the proposed method is robust in detecting and fitting the lane markings.
16. Full Waveform Inversion for Reservoir Characterization - A Synthetic Study
KAUST Repository
Zabihi Naeini, E.; Kamath, N.; Tsvankin, I.; Alkhalifah, Tariq Ali
2017-01-01
Most current reservoir-characterization workflows are based on classic amplitude-variation-with-offset (AVO) inversion techniques. Although these methods have generally served us well over the years, here we examine full-waveform inversion (FWI
17. Anisotropic wave-equation traveltime and waveform inversion
KAUST Repository
Feng, Shihang
2016-09-06
The wave-equation traveltime and waveform inversion (WTW) methodology is developed to invert for anisotropic parameters in a vertical transverse isotropic (VTI) meidum. The simultaneous inversion of anisotropic parameters v0, ε and δ is initially performed using the wave-equation traveltime inversion (WT) method. The WT tomograms are then used as starting background models for VTI full waveform inversion. Preliminary numerical tests on synthetic data demonstrate the feasibility of this method for multi-parameter inversion.
18. A microcomputer-based waveform generator for Moessbauer spectrometers
International Nuclear Information System (INIS)
Huang Jianping; Chen Xiaomei
1995-01-01
A waveform generator for Moessbauer spectrometers based on 8751 single chip microcomputer is described. The reference wave form with high linearity is generated with a 12 bit DAC, and its amplitude is controlled with a 8 bit DAC. Because the channel advance and synchronous signals can be delayed arbitrarily, excellent folded spectra can be acquired. This waveform generator can be controlled with DIP switches on faceplate or series interface of the IBM-PC microcomputer
19. Free-Standing Bilayered Nanoparticle Superlattice Nanosheets with Asymmetric Ionic Transport Behaviors.
Science.gov (United States)
Rao, Siyuan; Si, Kae Jye; Yap, Lim Wei; Xiang, Yan; Cheng, Wenlong
2015-11-24
Natural cell membranes can directionally and selectively regulate the ion transport, which is critical for the functioning of living cells. Here, we report on the fabrication of an artificial membrane based on an asymmetric nanoparticle superlattice bilayered nanosheet, which exhibits similar ion transport characteristics. The superlattice nanosheets were fabricated via a drying-mediated self-assembly of polystyrene-capped gold nanoparticles at the liquid-air interface. By adopting a layer-by-layer assembly process, an asymmetric nanomembrane could be obtained consisting of two nanosheets with different nanoparticle size. The resulting nanomembranes exhibit an asymmetric ion transport behavior, and diode-like current-voltage curves were observed. The asymmetric ion transport is attributed to the cone-like nanochannels formed within the membranes, upon which a simulation map was established to illustrate the relationship between the channel structure and the ionic selectivity, in consistency with our experimental results. Our superlattice nanosheet-based design presents a promising strategy for the fabrication of next-generation smart nanomembranes for rationally and selectively regulating the ion transport even at a large ion flux, with potential applications in a wide range of fields, including biosensor devices, energy conversion, biophotonics, and bioelectronics.
20. Asymmetric Penning trap coherent states
International Nuclear Information System (INIS)
Contreras-Astorga, Alonso; Fernandez, David J.
2010-01-01
By using a matrix technique, which allows to identify directly the ladder operators, the coherent states of the asymmetric Penning trap are derived as eigenstates of the appropriate annihilation operators. They are compared with those obtained through the displacement operator method.
1. JET and COMPASS asymmetrical disruptions
Czech Academy of Sciences Publication Activity Database
Gerasimov, S.N.; Abreu, P.; Baruzzo, M.; Drozdov, V.; Dvornova, A.; Havlíček, Josef; Hender, T.C.; Hronová-Bilyková, Olena; Kruezi, U.; Li, X.; Markovič, Tomáš; Pánek, Radomír; Rubinacci, G.; Tsalas, M.; Ventre, S.; Villone, F.; Zakharov, L.E.
2015-01-01
Roč. 55, č. 11 (2015), s. 113006-113006 ISSN 0029-5515 R&D Projects: GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : tokamak * asymmetrical disruption * JET * COMPASS Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.040, year: 2015
2. A Time Domain Waveform for Testing General Relativity
International Nuclear Information System (INIS)
Huwyler, Cédric; Jetzer, Philippe; Porter, Edward K
2015-01-01
Gravitational-wave parameter estimation is only as good as the theory the waveform generation models are based upon. It is therefore crucial to test General Relativity (GR) once data becomes available. Many previous works, such as studies connected with the ppE framework by Yunes and Pretorius, rely on the stationary phase approximation (SPA) to model deviations from GR in the frequency domain. As Fast Fourier Transform algorithms have become considerably faster and in order to circumvent possible problems with the SPA, we test GR with corrected time domain waveforms instead of SPA waveforms. Since a considerable amount of work has been done already in the field using SPA waveforms, we establish a connection between leading-order-corrected waveforms in time and frequency domain, concentrating on phase-only corrected terms. In a Markov Chain Monte Carlo study, whose results are preliminary and will only be available later, we will assess the ability of the eLISA detector to measure deviations from GR for signals coming from supermassive black hole inspirals using these corrected waveforms. (paper)
3. Phase-space topography characterization of nonlinear ultrasound waveforms.
Science.gov (United States)
Dehghan-Niri, Ehsan; Al-Beer, Helem
2018-03-01
Fundamental understanding of ultrasound interaction with material discontinuities having closed interfaces has many engineering applications such as nondestructive evaluation of defects like kissing bonds and cracks in critical structural and mechanical components. In this paper, to analyze the acoustic field nonlinearities due to defects with closed interfaces, the use of a common technique in nonlinear physics, based on a phase-space topography construction of ultrasound waveform, is proposed. The central idea is to complement the "time" and "frequency" domain analyses with the "phase-space" domain analysis of nonlinear ultrasound waveforms. A nonlinear time series method known as pseudo phase-space topography construction is used to construct equivalent phase-space portrait of measured ultrasound waveforms. Several nonlinear models are considered to numerically simulate nonlinear ultrasound waveforms. The phase-space response of the simulated waveforms is shown to provide different topographic information, while the frequency domain shows similar spectral behavior. Thus, model classification can be substantially enhanced in the phase-space domain. Experimental results on high strength aluminum samples show that the phase-space transformation provides a unique detection and classification capabilities. The Poincaré map of the phase-space domain is also used to better understand the nonlinear behavior of ultrasound waveforms. It is shown that the analysis of ultrasound nonlinearities is more convenient and informative in the phase-space domain than in the frequency domain. Copyright © 2017 Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
Xiaowen Zhang
2018-02-01
Full Text Available In this paper, the problem of cognitive radar (CR waveform optimization design for target detection and estimation in multiple extended targets situations is investigated. This problem is analyzed in signal-dependent interference, as well as additive channel noise for extended targets with unknown target impulse response (TIR. To address this problem, an improved algorithm is employed for target detection by maximizing the detection probability of the received echo on the promise of ensuring the TIR estimation precision. In this algorithm, an additional weight vector is introduced to achieve a trade-off among different targets. Both the estimate of TIR and transmit waveform can be updated at each step based on the previous step. Under the same constraint on waveform energy and bandwidth, the information theoretical approach is also considered. In addition, the relationship between the waveforms that are designed based on the two criteria is discussed. Unlike most existing works that only consider single target with temporally correlated characteristics, waveform design for multiple extended targets is considered in this method. Simulation results demonstrate that compared with linear frequency modulated (LFM signal, waveforms designed based on maximum detection probability and maximum mutual information (MI criteria can make radar echoes contain more multiple-target information and improve radar performance as a result.
5. Adaptive phase k-means algorithm for waveform classification
Science.gov (United States)
Song, Chengyun; Liu, Zhining; Wang, Yaojun; Xu, Feng; Li, Xingming; Hu, Guangmin
2018-01-01
Waveform classification is a powerful technique for seismic facies analysis that describes the heterogeneity and compartments within a reservoir. Horizon interpretation is a critical step in waveform classification. However, the horizon often produces inconsistent waveform phase, and thus results in an unsatisfied classification. To alleviate this problem, an adaptive phase waveform classification method called the adaptive phase k-means is introduced in this paper. Our method improves the traditional k-means algorithm using an adaptive phase distance for waveform similarity measure. The proposed distance is a measure with variable phases as it moves from sample to sample along the traces. Model traces are also updated with the best phase interference in the iterative process. Therefore, our method is robust to phase variations caused by the interpretation horizon. We tested the effectiveness of our algorithm by applying it to synthetic and real data. The satisfactory results reveal that the proposed method tolerates certain waveform phase variation and is a good tool for seismic facies analysis.
6. Optimal current waveforms for brushless permanent magnet motors
Science.gov (United States)
Moehle, Nicholas; Boyd, Stephen
2015-07-01
In this paper, we give energy-optimal current waveforms for a permanent magnet synchronous motor that result in a desired average torque. Our formulation generalises previous work by including a general back-electromotive force (EMF) wave shape, voltage and current limits, an arbitrary phase winding connection, a simple eddy current loss model, and a trade-off between power loss and torque ripple. Determining the optimal current waveforms requires solving a small convex optimisation problem. We show how to use the alternating direction method of multipliers to find the optimal current in milliseconds or hundreds of microseconds, depending on the processor used, which allows the possibility of generating optimal waveforms in real time. This allows us to adapt in real time to changes in the operating requirements or in the model, such as a change in resistance with winding temperature, or even gross changes like the failure of one winding. Suboptimal waveforms are available in tens or hundreds of microseconds, allowing for quick response after abrupt changes in the desired torque. We demonstrate our approach on a simple numerical example, in which we give the optimal waveforms for a motor with a sinusoidal back-EMF, and for a motor with a more complicated, nonsinusoidal waveform, in both the constant-torque region and constant-power region.
7. Frequency-domain waveform inversion using the unwrapped phase
KAUST Repository
Choi, Yun Seok
2011-01-01
Phase wrapping in the frequency-domain (or cycle skipping in the time-domain) is the major cause of the local minima problem in the waveform inversion. The unwrapped phase has the potential to provide us with a robust and reliable waveform inversion, with reduced local minima. We propose a waveform inversion algorithm using the unwrapped phase objective function in the frequency-domain. The unwrapped phase, or what we call the instantaneous traveltime, is given by the imaginary part of dividing the derivative of the wavefield with respect to the angular frequency by the wavefield itself. As a result, the objective function is given a traveltime-like function, which allows us to smooth it and reduce its nonlinearity. The gradient of the objective function is computed using the back-propagation algorithm based on the adjoint-state technique. We apply both our waveform inversion algorithm using the unwrapped phase and the conventional waveform inversion and show that our inversion algorithm gives better convergence to the true model than the conventional waveform inversion. © 2011 Society of Exploration Geophysicists.
8. 3D Electric Waveforms of Solar Wind Turbulence
Science.gov (United States)
Kellogg, P. J.; Goetz, K.; Monson, S. J.
2018-01-01
Electric fields provide the major coupling between the turbulence of the solar wind and particles. A large part of the turbulent spectrum of fluctuations in the solar wind is thought to be kinetic Alfvén waves; however, whistlers have recently been found to be important. In this article, we attempt to determine the mode identification of individual waveforms using the three-dimensional antenna system of the SWaves experiments on the STEREO spacecraft. Samples are chosen using waveforms with an apparent periodic structure, selected visually. The short antennas of STEREO respond to density fluctuations and to electric fields. Measurement of four quantities using only three antennas presents a problem. Methods to overcome or to ignore this difficulty are presented. We attempt to decide whether the waveforms correspond to the whistler mode or the Alfvén mode by using the direction of rotation of the signal. Most of the waveforms are so oblique—nearly linearly polarized—that the direction cannot be determined. However, about one third of the waveforms can be identified, and whistlers and Alfvén waves are present in roughly equal numbers. The selected waveforms are very intense but intermittent and are orders of magnitude stronger than the average, yet their accumulated signal accounts for a large fraction of the average. The average, however, is supposed to be the result of a turbulent mixture of many waves, not short coherent events. This presents a puzzle for future work.
9. Development of ion-acoustic double layers through ion-acoustic fluctuations
International Nuclear Information System (INIS)
Sekar, A.N.; Saxena, Y.C.
1985-01-01
Experimental results on the formation of ion acoustic double layers resembling asymmetric ion-holes are presented. In a double plasma device, modified suitably to inject electron beam into the target plasma, modulation of the beam through step potential leads to excitation of ion-acoustic fluctuation. The ion-acoustic fluctuation, growing away from the grids separating source and target plasmas, developed into weak asymmetric ion-acoustic double layer. The observations are in qualitative agreement with theoretical models and computer simulations. (author)
10. Source-independent time-domain waveform inversion using convolved wavefields: Application to the encoded multisource waveform inversion
KAUST Repository
Choi, Yun Seok; Alkhalifah, Tariq Ali
2011-01-01
Full waveform inversion requires a good estimation of the source wavelet to improve our chances of a successful inversion. This is especially true for an encoded multisource time-domain implementation, which, conventionally, requires separate
11. System and Method for Generating a Frequency Modulated Linear Laser Waveform
Science.gov (United States)
Pierrottet, Diego F. (Inventor); Petway, Larry B. (Inventor); Amzajerdian, Farzin (Inventor); Barnes, Bruce W. (Inventor); Lockard, George E. (Inventor); Hines, Glenn D. (Inventor)
2017-01-01
A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.
12. Hierarchical polypyrrole based composites for high performance asymmetric supercapacitors
Science.gov (United States)
Chen, Gao-Feng; Liu, Zhao-Qing; Lin, Jia-Ming; Li, Nan; Su, Yu-Zhi
2015-06-01
An advanced asymmetric supercapacitor with high energy density, exploiting hierarchical polypyrrole (PPy) based composites as both the anode [three dimensional (3D) chuzzle-like Ni@PPy@MnO2] and (3D cochleate-like Ni@MnO2@PPy) cathode, has been developed. The ultrathin PPy and flower-like MnO2 orderly coating on the high-conductivity 3D-Ni enhance charge storage while the unique 3D chuzzle-like and 3D cochleate-like structures provide storage chambers and fast ion transport pathways for benefiting the transport of electrolyte ions. The 3D cochleate-like Ni@MnO2@PPy possesses excellent pseudocapacitance with a relatively negative voltage window while preserved EDLC and free transmission channels conducive to hold the high power, providing an ideal cathode for the asymmetric supercapacitor. It is the first report of assembling hierarchical PPy based composites as both the anode and cathode for asymmetric supercapacitor, which exhibits wide operation voltage of 1.3-1.5 V with maximum energy and power densities of 59.8 Wh kg-1 and 7500 W kg-1.
13. Extension of frequency-based dissimilarity for retrieving similar plasma waveforms
International Nuclear Information System (INIS)
Hochin, Teruhisa; Koyama, Katsumasa; Nakanishi, Hideya; Kojima, Mamoru
2008-01-01
Some computer-aided assistance in finding the waveforms similar to a waveform has become indispensable for accelerating data analysis in the plasma experiments. For the slowly-varying waveforms and those having time-sectional oscillation patterns, the methods using the Fourier series coefficients of waveforms in calculating the dissimilarity have successfully improved the performance in retrieving similar waveforms. This paper treats severely-varying waveforms, and proposes two extensions to the dissimilarity of waveforms. The first extension is to capture the difference of the importance of the Fourier series coefficients of waveforms against frequency. The second extension is to consider the outlines of waveforms. The correctness of the extended dissimilarity is experimentally evaluated by using the metrics used in evaluating that of the information retrieval, i.e. precision and recall. The experimental results show that the extended dissimilarity could improve the correctness of the similarity retrieval of plasma waveforms
14. Pseudo LRM waveforms from CryoSat SARin acquisition
Science.gov (United States)
Scagliola, Michele; Fornari, Marco; Bouffard, Jerome; Parrinello, Tommaso; Féménias, Pierre
2016-04-01
CryoSat was launched on the 8th April 2010 and is the first European ice mission dedicated to the monitoring of precise changes in the thickness of polar ice sheets and floating sea ice. The main payload of CryoSat is a Ku-band pulsewidth limited radar altimeter, called SIRAL (Synthetic interferometric radar altimeter). When commanded in SARIn (synthetic aperture radar interferometry) mode, through coherent along-track processing of the returns received from two antennas, the interferometric phase related to the first arrival of the echo is used to retrieve the angle of arrival of the scattering in the across-track direction. When SIRAL operates in SAR or SARin mode, the obtained waveforms have an along-track resolution and a speckle reduction which is increased with respect to the pulse-limited waveforms. Anyway, in order to analyze the continuity of the geophysical retrieved parameters among different acquisition modes, techniques to transform SARin mode data to pseudo-LRM mode data are welcome. The transformation process is known as SAR reduction and it is worth recalling here that only approximate pseudo-LRM waveforms can be obtained in case of closed burst acquisitions, as SIRAL operates. A SAR reduction processing scheme has been developed to obtain pseudo-LRM waveforms from CryoSat SARin acquisition. As a trade-off between the along-track length on Earth surface contributing to one SARin pseudo-LRM waveform and the noisiness of the waveform itself, it has been chosen a SAR reduction approach based on the averaging of all the SARin echoes received each 20Hz, resulting in one pseudo-LRM waveform for each SARin burst given the SARin burst repetition period. SARin pseudo-LRM waveforms have been produced for CryoSat acquisition both on ice and sea surfaces, aiming at verifying the continuity of the retracked surface height over the ellipsoid between genuine LRM products and pseudo-LRM products. Moreover, the retracked height from the SARin pseudo-LRM has been
15. Cyclodextrins in Asymmetric and Stereospecific Synthesis
Directory of Open Access Journals (Sweden)
Fliur Macaev
2015-09-01
Full Text Available Since their discovery, cyclodextrins have widely been used as green and easily available alternatives to promoters or catalysts of different chemical reactions in water. This review covers the research and application of cyclodextrins and their derivatives in asymmetric and stereospecific syntheses, with their division into three main groups: (1 cyclodextrins promoting asymmetric and stereospecific catalysis in water; (2 cyclodextrins’ complexes with transition metals as asymmetric and stereospecific catalysts; and (3 cyclodextrins’ non-metallic derivatives as asymmetric and stereospecific catalysts. The scope of this review is to systematize existing information on the contribution of cyclodextrins to asymmetric and stereospecific synthesis and, thus, to facilitate further development in this direction.
16. Stable walking with asymmetric legs
International Nuclear Information System (INIS)
Merker, Andreas; Rummel, Juergen; Seyfarth, Andre
2011-01-01
Asymmetric leg function is often an undesired side-effect in artificial legged systems and may reflect functional deficits or variations in the mechanical construction. It can also be found in legged locomotion in humans and animals such as after an accident or in specific gait patterns. So far, it is not clear to what extent differences in the leg function of contralateral limbs can be tolerated during walking or running. Here, we address this issue using a bipedal spring-mass model for simulating walking with compliant legs. With the help of the model, we show that considerable differences between contralateral legs can be tolerated and may even provide advantages to the robustness of the system dynamics. A better understanding of the mechanisms and potential benefits of asymmetric leg operation may help to guide the development of artificial limbs or the design novel therapeutic concepts and rehabilitation strategies.
17. Variable angle asymmetric cut monochromator
International Nuclear Information System (INIS)
Smither, R.K.; Fernandez, P.B.
1993-09-01
A variable incident angle, asymmetric cut, double crystal monochromator was tested for use on beamlines at the Advanced Photon Source (APS). For both undulator and wiggler beams the monochromator can expand area of footprint of beam on surface of the crystals to 50 times the area of incident beam; this will reduce the slope errors by a factor of 2500. The asymmetric cut allows one to increase the acceptance angle for incident radiation and obtain a better match to the opening angle of the incident beam. This can increase intensity of the diffracted beam by a factor of 2 to 5 and can make the beam more monochromatic, as well. The monochromator consists of two matched, asymmetric cut (18 degrees), silicon crystals mounted so that they can be rotated about three independent axes. Rotation around the first axis controls the Bragg angle. The second rotation axis is perpendicular to the diffraction planes and controls the increase of the area of the footprint of the beam on the crystal surface. Rotation around the third axis controls the angle between the surface of the crystal and the wider, horizontal axis for the beam and can make the footprint a rectangle with a minimum. length for this area. The asymmetric cut is 18 degrees for the matched pair of crystals, which allows one to expand the footprint area by a factor of 50 for Bragg angles up to 19.15 degrees (6 keV for Si[111] planes). This monochromator, with proper cooling, will be useful for analyzing the high intensity x-ray beams produced by both undulators and wigglers at the APS
18. Asymmetric information and bank runs
OpenAIRE
Gu, Chao
2007-01-01
It is known that sunspots can trigger panic-based bank runs and that the optimal banking contract can tolerate panic-based runs. The existing literature assumes that these sunspots are based on a publicly observed extrinsic randomizing device. In this paper, I extend the analysis of panic-based runs to include an asymmetric-information, extrinsic randomizing device. Depositors observe different, but correlated, signals on the stability of the bank. I find that if the signals that depositors o...
19. Asymmetric information and macroeconomic dynamics
Science.gov (United States)
Hawkins, Raymond J.; Aoki, Masanao; Roy Frieden, B.
2010-09-01
We show how macroeconomic dynamics can be derived from asymmetric information. As an illustration of the utility of this approach we derive the equilibrium density, non-equilibrium densities and the equation of motion for the response to a demand shock for productivity in a simple economy. Novel consequences of this approach include a natural incorporation of time dependence into macroeconomics and a common information-theoretic basis for economics and other fields seeking to link micro-dynamics and macro-observables.
20. Asymmetric Synthesis of Apratoxin E.
Science.gov (United States)
Mao, Zhuo-Ya; Si, Chang-Mei; Liu, Yi-Wen; Dong, Han-Qing; Wei, Bang-Guo; Lin, Guo-Qiang
2016-10-21
An efficient method for asymmetric synthesis of apratoxin E 2 is described in this report. The chiral lactone 8, recycled from the degradation of saponin glycosides, was utilized to prepare the non-peptide fragment 6. In addition to this "from nature to nature" strategy, olefin cross-metathesis (CM) was applied as an alternative approach for the formation of the double bond. Moreover, pentafluorophenyl diphenylphosphinate was found to be an efficient condensation reagent for the macrocyclization.
1. Comprehensive asymmetric dark matter model
OpenAIRE
Lonsdale, Stephen J.; Volkas, Raymond R.
2018-01-01
Asymmetric dark matter (ADM) is motivated by the similar cosmological mass densities measured for ordinary and dark matter. We present a comprehensive theory for ADM that addresses the mass density similarity, going beyond the usual ADM explanations of similar number densities. It features an explicit matter-antimatter asymmetry generation mechanism, has one fully worked out thermal history and suggestions for other possibilities, and meets all phenomenological, cosmological and astrophysical...
2. Time resolved ion beam induced charge collection
International Nuclear Information System (INIS)
Sexton W, Frederick; Walsh S, David; Doyle L, Barney; Dodd E, Paul
2000-01-01
Under this effort, a new method for studying the single event upset (SEU) in microelectronics has been developed and demonstrated. Called TRIBICC, for Time Resolved Ion Beam Induced Charge Collection, this technique measures the transient charge-collection waveform from a single heavy-ion strike with a -.03db bandwidth of 5 GHz. Bandwidth can be expanded up to 15 GHz (with 5 ps sampling windows) by using an FFT-based off-line waveform renormalization technique developed at Sandia. The theoretical time resolution of the digitized waveform is 24 ps with data re-normalization and 70 ps without re-normalization. To preserve the high bandwidth from IC to the digitizing oscilloscope, individual test structures are assembled in custom high-frequency fixtures. A leading-edge digitized waveform is stored with the corresponding ion beam position at each point in a two-dimensional raster scan. The resulting data cube contains a spatial charge distribution map of up to 4,096 traces of charge (Q) collected as a function of time. These two dimensional traces of Q(t) can cover a period as short as 5 ns with up to 1,024 points per trace. This tool overcomes limitations observed in previous multi-shot techniques due to the displacement damage effects of multiple ion strikes that changed the signal of interest during its measurement. This system is the first demonstration of a single-ion transient measurement capability coupled with spatial mapping of fast transients
3. Time resolved ion beam induced charge collection
Energy Technology Data Exchange (ETDEWEB)
SEXTON,FREDERICK W.; WALSH,DAVID S.; DOYLE,BARNEY L.; DODD,PAUL E.
2000-04-01
Under this effort, a new method for studying the single event upset (SEU) in microelectronics has been developed and demonstrated. Called TRIBICC, for Time Resolved Ion Beam Induced Charge Collection, this technique measures the transient charge-collection waveform from a single heavy-ion strike with a {minus}.03db bandwidth of 5 GHz. Bandwidth can be expanded up to 15 GHz (with 5 ps sampling windows) by using an FFT-based off-line waveform renormalization technique developed at Sandia. The theoretical time resolution of the digitized waveform is 24 ps with data re-normalization and 70 ps without re-normalization. To preserve the high bandwidth from IC to the digitizing oscilloscope, individual test structures are assembled in custom high-frequency fixtures. A leading-edge digitized waveform is stored with the corresponding ion beam position at each point in a two-dimensional raster scan. The resulting data cube contains a spatial charge distribution map of up to 4,096 traces of charge (Q) collected as a function of time. These two dimensional traces of Q(t) can cover a period as short as 5 ns with up to 1,024 points per trace. This tool overcomes limitations observed in previous multi-shot techniques due to the displacement damage effects of multiple ion strikes that changed the signal of interest during its measurement. This system is the first demonstration of a single-ion transient measurement capability coupled with spatial mapping of fast transients.
4. A mean-field theory on the differential capacitance of asymmetric ionic liquid electrolytes
International Nuclear Information System (INIS)
Han, Yining; Huang, Shanghui; Yan, Tianying
2014-01-01
The size of ions significantly influences the electric double layer structure of room temperature ionic liquid (IL) electrolytes and their differential capacitance (C d ). In this study, we extended the mean-field theory (MFT) developed independently by Kornyshev (2007J. Phys. Chem. B 111 5545–57) and Kilic, Bazant, and Ajdari (2007 Phys. Rev. E 75 021502) (the KKBA MFT) to take into account the asymmetric 1:1 IL electrolytes by introducing an additional parameter ξ for the anion/cation volume ratio, besides the ionic compressibility γ in the KKBA MFT. The MFT of asymmetric ions becomes KKBA MFT upon ξ = 1, and further reduces to Gouy–Chapman theory in the γ → 0 limit. The result of the extended MFT demonstrates that the asymmetric ILs give rise to an asymmetric C d , with the higher peak in C d occurring at positive polarization for the smaller anionic size. At high potential, C d decays asymptotically toward KKBA MFT characterized by γ for the negative polarization, and characterized by ξγ for the positive polarization, with inverse-square-root behavior. At low potential, around the potential of zero charge, the asymmetric ions cause a higher C d , which exceeds that of Gouy–Chapman theory. (paper)
5. A mean-field theory on the differential capacitance of asymmetric ionic liquid electrolytes.
Science.gov (United States)
Han, Yining; Huang, Shanghui; Yan, Tianying
2014-07-16
The size of ions significantly influences the electric double layer structure of room temperature ionic liquid (IL) electrolytes and their differential capacitance (Cd). In this study, we extended the mean-field theory (MFT) developed independently by Kornyshev (2007J. Phys. Chem. B 111 5545-57) and Kilic, Bazant, and Ajdari (2007 Phys. Rev. E 75 021502) (the KKBA MFT) to take into account the asymmetric 1:1 IL electrolytes by introducing an additional parameter ξ for the anion/cation volume ratio, besides the ionic compressibility γ in the KKBA MFT. The MFT of asymmetric ions becomes KKBA MFT upon ξ = 1, and further reduces to Gouy-Chapman theory in the γ → 0 limit. The result of the extended MFT demonstrates that the asymmetric ILs give rise to an asymmetric Cd, with the higher peak in Cd occurring at positive polarization for the smaller anionic size. At high potential, Cd decays asymptotically toward KKBA MFT characterized by γ for the negative polarization, and characterized by ξγ for the positive polarization, with inverse-square-root behavior. At low potential, around the potential of zero charge, the asymmetric ions cause a higher Cd, which exceeds that of Gouy-Chapman theory.
6. Ocular pressure waveform reflects ventricular bigeminy and aortic insufficiency
Directory of Open Access Journals (Sweden)
Jean B Kassem
2015-01-01
Full Text Available Ocular pulse amplitude (OPA is defined as the difference between maximum and minimum intraocular pressure (IOP during a cardiac cycle. Average values of OPA range from 1 to 4 mmHg. The purpose of this investigation is to determine the source of an irregular IOP waveform with elevated OPA in a 48-year-old male. Ocular pressure waveforms had an unusual shape consistent with early ventricular contraction. With a normal IOP, OPA was 9 mmHg, which is extraordinarily high. The subject was examined by a cardiologist and was determined to be in ventricular bigeminy. In addition, he had bounding carotid pulses and echocardiogram confirmed aortic insufficiency. After replacement of the aortic valve, the bigeminy resolved and the ocular pulse waveform became regular in appearance with an OPA of 1.6-2.0 mmHg. The ocular pressure waveform is a direct reflection of hemodynamics. Evaluating this waveform may provide an additional opportunity for screening subjects for cardiovascular anomalies and arrhythmias.
7. Direct current contamination of kilohertz frequency alternating current waveforms.
Science.gov (United States)
2014-07-30
Kilohertz frequency alternating current (KHFAC) waveforms are being evaluated in a variety of physiological settings because of their potential to modulate neural activity uniquely when compared to frequencies in the sub-kilohertz range. However, the use of waveforms in this frequency range presents some unique challenges regarding the generator output. In this study we explored the possibility of undesirable contamination of the KHFAC waveforms by direct current (DC). We evaluated current- and voltage-controlled KHFAC waveform generators in configurations that included a capacitive coupling between generator and electrode, a resistive coupling and combinations of capacitive with inductive coupling. Our results demonstrate that both voltage- and current-controlled signal generators can unintentionally add DC-contamination to a KHFAC signal, and that capacitive coupling is not always sufficient to eliminate this contamination. We furthermore demonstrated that high value inductors, placed in parallel with the electrode, can be effective in eliminating DC-contamination irrespective of the type of stimulator, reducing the DC contamination to less than 1 μA. This study highlights the importance of carefully designing the electronic setup used in KHFAC studies and suggests specific testing that should be performed and reported in all studies that assess the neural response to KHFAC waveforms. Published by Elsevier B.V.
8. Accuracy of Binary Black Hole waveforms for Advanced LIGO searches
Science.gov (United States)
Kumar, Prayush; Barkett, Kevin; Bhagwat, Swetha; Chu, Tony; Fong, Heather; Brown, Duncan; Pfeiffer, Harald; Scheel, Mark; Szilagyi, Bela
2015-04-01
Coalescing binaries of compact objects are flagship sources for the first direct detection of gravitational waves with LIGO-Virgo observatories. Matched-filtering based detection searches aimed at binaries of black holes will use aligned spin waveforms as filters, and their efficiency hinges on the accuracy of the underlying waveform models. A number of gravitational waveform models are available in literature, e.g. the Effective-One-Body, Phenomenological, and traditional post-Newtonian ones. While Numerical Relativity (NR) simulations provide for the most accurate modeling of gravitational radiation from compact binaries, their computational cost limits their application in large scale searches. In this talk we assess the accuracy of waveform models in two regions of parameter space, which have only been explored cursorily in the past: the high mass-ratio regime as well as the comparable mass-ratio + high spin regime.s Using the SpEC code, six q = 7 simulations with aligned-spins and lasting 60 orbits, and tens of q ∈ [1,3] simulations with high black hole spins were performed. We use them to study the accuracy and intrinsic parameter biases of different waveform families, and assess their viability for Advanced LIGO searches.
9. A study of doppler waveform using pulsatile flow model
International Nuclear Information System (INIS)
Chung, Hye Won; Chung, Myung Jin; Park, Jae Hyung; Chung, Jin Wook; Lee, Dong Hyuk; Min, Byoung Goo
1997-01-01
Through the construction of a pulsatile flow model using an artificial heart pump and stenosis to demonstrate triphasic Doppler waveform, which simulates in vivo conditions, and to evaluate the relationship between Doppler waveform and vascular compliance. The flow model was constructed using a flowmeter, rubber tube, glass tube with stenosis, and artificial heart pump. Doppler study was carried out at the prestenotic, poststenotic, and distal segments;compliance was changed by changing the length of the rubber tube. With increasing proximal compliance, Doppler waveforms show decreasing peak velocity of the first phase and slightly delayed acceleration time, but the waveform itself did not change significantly. Distal compliance influenced the second phase, and was important for the formation of pulsus tardus and parvus, which without poststenotic vascular compliance, did not develop. The peak velocity of the first phase was inversely proportional to proximal compliance, and those of the second and third phases were directly proportional to distal compliance. After constructing this pulsatile flow model, we were able to explain the relationship between vascular compliance and Doppler waveform, and also better understand the formation of pulsus tardus and parvus
10. Closed-loop waveform control of boost inverter
DEFF Research Database (Denmark)
Zhu, Guo Rong; Xiao, Cheng Yuan; Wang, Haoran
2016-01-01
The input current of single-phase inverter typically has an AC ripple component at twice the output frequency, which causes a reduction in both the operating lifetime of its DC source and the efficiency of the system. In this paper, the closed-loop performance of a proposed waveform control method...... to eliminate such a ripple current in boost inverter is investigated. The small-signal stability and the dynamic characteristic of the inverter system for input voltage or wide range load variations under the closed-loop waveform control method are studied. It is validated that with the closedloop waveform...... control, not only was stability achieved, the reference voltage of the boost inverter capacitors can be instantaneously adjusted to match the new load, thereby achieving improved ripple mitigation for a wide load range. Furthermore, with the control and feedback mechanism, there is minimal level of ripple...
11. Designing waveforms for temporal encoding using a frequency sampling method
DEFF Research Database (Denmark)
Gran, Fredrik; Jensen, Jørgen Arendt
2007-01-01
was compared to a linear frequency modulated signal with amplitude tapering, previously used in clinical studies for synthetic transmit aperture imaging. The latter had a relatively flat spectrum which implied that the waveform tried to excite all frequencies including ones with low amplification. The proposed......In this paper a method for designing waveforms for temporal encoding in medical ultrasound imaging is described. The method is based on least squares optimization and is used to design nonlinear frequency modulated signals for synthetic transmit aperture imaging. By using the proposed design method...... waveform, on the other hand, was designed so that only frequencies where the transducer had a large amplification were excited. Hereby, unnecessary heating of the transducer could be avoided and the signal-tonoise ratio could be increased. The experimental ultrasound scanner RASMUS was used to evaluate...
12. Stimulator with arbitrary waveform for auditory evoked potentials
International Nuclear Information System (INIS)
Martins, H R; Romao, M; Placido, D; Provenzano, F; Tierra-Criollo, C J
2007-01-01
The technological improvement helps many medical areas. The audiometric exams involving the auditory evoked potentials can make better diagnoses of auditory disorders. This paper proposes the development of a stimulator based on Digital Signal Processor. This stimulator is the first step of an auditory evoked potential system based on the ADSP-BF533 EZ KIT LITE (Analog Devices Company - USA). The stimulator can generate arbitrary waveform like Sine Waves, Modulated Amplitude, Pulses, Bursts and Pips. The waveforms are generated through a graphical interface programmed in C++ in which the user can define the parameters of the waveform. Furthermore, the user can set the exam parameters as number of stimuli, time with stimulation (Time ON) and time without stimulus (Time OFF). In future works will be implemented another parts of the system that includes the acquirement of electroencephalogram and signal processing to estimate and analyze the evoked potential
13. Stimulator with arbitrary waveform for auditory evoked potentials
Energy Technology Data Exchange (ETDEWEB)
Martins, H R; Romao, M; Placido, D; Provenzano, F; Tierra-Criollo, C J [Universidade Federal de Minas Gerais (UFMG), Departamento de Engenharia Eletrica (DEE), Nucleo de Estudos e Pesquisa em Engenharia Biomedica NEPEB, Av. Ant. Carlos, 6627, sala 2206, Pampulha, Belo Horizonte, MG, 31.270-901 (Brazil)
2007-11-15
The technological improvement helps many medical areas. The audiometric exams involving the auditory evoked potentials can make better diagnoses of auditory disorders. This paper proposes the development of a stimulator based on Digital Signal Processor. This stimulator is the first step of an auditory evoked potential system based on the ADSP-BF533 EZ KIT LITE (Analog Devices Company - USA). The stimulator can generate arbitrary waveform like Sine Waves, Modulated Amplitude, Pulses, Bursts and Pips. The waveforms are generated through a graphical interface programmed in C++ in which the user can define the parameters of the waveform. Furthermore, the user can set the exam parameters as number of stimuli, time with stimulation (Time ON) and time without stimulus (Time OFF). In future works will be implemented another parts of the system that includes the acquirement of electroencephalogram and signal processing to estimate and analyze the evoked potential.
14. Generating Correlated QPSK Waveforms By Exploiting Real Gaussian Random Variables
KAUST Repository
Jardak, Seifallah
2012-11-01
The design of waveforms with specified auto- and cross-correlation properties has a number of applications in multiple-input multiple-output (MIMO) radar, one of them is the desired transmit beampattern design. In this work, an algorithm is proposed to generate quadrature phase shift- keying (QPSK) waveforms with required cross-correlation properties using real Gaussian random-variables (RV’s). This work can be considered as the extension of what was presented in [1] to generate BPSK waveforms. This work will be extended for the generation of correlated higher-order phase shift-keying (PSK) and quadrature amplitude modulation (QAM) schemes that can better approximate the desired beampattern.
15. Analysis of Gradient Waveform in Magnetic Resonance Imaging
Directory of Open Access Journals (Sweden)
OU-YANG Shan-mei
2017-12-01
Full Text Available The accuracy of gradient pulse waveform affects image quality significantly in magnetic resonance imaging (MRI. Recording and analyzing the waveform of gradient pulse helps to make rapid and accurate diagnosis of spectrometer gradient hardware and/or pulse sequence. Using the virtual instrument software LabVIEW to control the high speed data acquisition card DAQ-2005, a multi-channel acquisition scheme was designed to collect the gradient outputs from a custom-made spectrometer. The collected waveforms were post-processed (i.e., histogram statistical analysis, data filtering and difference calculation to obtain feature points containing time and amplitude information. Experiments were carried out to validate the method, which is an auxiliary test method for the development of spectrometer and pulses sequence.
16. A complete waveform model for compact binaries on eccentric orbits
Science.gov (United States)
George, Daniel; Huerta, Eliu; Kumar, Prayush; Agarwal, Bhanu; Schive, Hsi-Yu; Pfeiffer, Harald; Chu, Tony; Boyle, Michael; Hemberger, Daniel; Kidder, Lawrence; Scheel, Mark; Szilagyi, Bela
2017-01-01
We present a time domain waveform model that describes the inspiral, merger and ringdown of compact binary systems whose components are non-spinning, and which evolve on orbits with low to moderate eccentricity. We show that this inspiral-merger-ringdown waveform model reproduces the effective-one-body model for black hole binaries with mass-ratios between 1 to 15 in the zero eccentricity limit over a wide range of the parameter space under consideration. We use this model to show that the gravitational wave transients GW150914 and GW151226 can be effectively recovered with template banks of quasicircular, spin-aligned waveforms if the eccentricity e0 of these systems when they enter the aLIGO band at a gravitational wave frequency of 14 Hz satisfies e0GW 150914 <= 0 . 15 and e0GW 151226 <= 0 . 1 .
17. Classification of Pulse Waveforms Using Edit Distance with Real Penalty
Directory of Open Access Journals (Sweden)
Zhang Dongyu
2010-01-01
Full Text Available Abstract Advances in sensor and signal processing techniques have provided effective tools for quantitative research in traditional Chinese pulse diagnosis (TCPD. Because of the inevitable intraclass variation of pulse patterns, the automatic classification of pulse waveforms has remained a difficult problem. In this paper, by referring to the edit distance with real penalty (ERP and the recent progress in -nearest neighbors (KNN classifiers, we propose two novel ERP-based KNN classifiers. Taking advantage of the metric property of ERP, we first develop an ERP-induced inner product and a Gaussian ERP kernel, then embed them into difference-weighted KNN classifiers, and finally develop two novel classifiers for pulse waveform classification. The experimental results show that the proposed classifiers are effective for accurate classification of pulse waveform.
18. Generating Correlated QPSK Waveforms By Exploiting Real Gaussian Random Variables
KAUST Repository
Jardak, Seifallah; Ahmed, Sajid; Alouini, Mohamed-Slim
2012-01-01
The design of waveforms with specified auto- and cross-correlation properties has a number of applications in multiple-input multiple-output (MIMO) radar, one of them is the desired transmit beampattern design. In this work, an algorithm is proposed to generate quadrature phase shift- keying (QPSK) waveforms with required cross-correlation properties using real Gaussian random-variables (RV’s). This work can be considered as the extension of what was presented in [1] to generate BPSK waveforms. This work will be extended for the generation of correlated higher-order phase shift-keying (PSK) and quadrature amplitude modulation (QAM) schemes that can better approximate the desired beampattern.
19. Shaping the spectrum of random-phase radar waveforms
Science.gov (United States)
Doerry, Armin W.; Marquette, Brandeis
2017-05-09
The various technologies presented herein relate to generation of a desired waveform profile in the form of a spectrum of apparently random noise (e.g., white noise or colored noise), but with precise spectral characteristics. Hence, a waveform profile that could be readily determined (e.g., by a spoofing system) is effectively obscured. Obscuration is achieved by dividing the waveform into a series of chips, each with an assigned frequency, wherein the sequence of chips are subsequently randomized. Randomization can be a function of the application of a key to the chip sequence. During processing of the echo pulse, a copy of the randomized transmitted pulse is recovered or regenerated against which the received echo is correlated. Hence, with the echo energy range-compressed in this manner, it is possible to generate a radar image with precise impulse response.
20. Ion mobility sensor system
Science.gov (United States)
Xu, Jun; Watson, David B.; Whitten, William B.
2013-01-22
An ion mobility sensor system including an ion mobility spectrometer and a differential mobility spectrometer coupled to the ion mobility spectrometer. The ion mobility spectrometer has a first chamber having first end and a second end extending along a first direction, and a first electrode system that generates a constant electric field parallel to the first direction. The differential mobility spectrometer includes a second chamber having a third end and a fourth end configured such that a fluid may flow in a second direction from the third end to the fourth end, and a second electrode system that generates an asymmetric electric field within an interior of the second chamber. Additionally, the ion mobility spectrometer and the differential mobility spectrometer form an interface region. Also, the first end and the third end are positioned facing one another so that the constant electric field enters the third end and overlaps the fluid flowing in the second direction.
1. Improving waveform inversion using modified interferometric imaging condition
Science.gov (United States)
Guo, Xuebao; Liu, Hong; Shi, Ying; Wang, Weihong; Zhang, Zhen
2018-02-01
Similar to the reverse-time migration, full waveform inversion in the time domain is a memory-intensive processing method. The computational storage size for waveform inversion mainly depends on the model size and time recording length. In general, 3D and 4D data volumes need to be saved for 2D and 3D waveform inversion gradient calculations, respectively. Even the boundary region wavefield-saving strategy creates a huge storage demand. Using the last two slices of the wavefield to reconstruct wavefields at other moments through the random boundary, avoids the need to store a large number of wavefields; however, traditional random boundary method is less effective at low frequencies. In this study, we follow a new random boundary designed to regenerate random velocity anomalies in the boundary region for each shot of each iteration. The results obtained using the random boundary condition in less illuminated areas are more seriously affected by random scattering than other areas due to the lack of coverage. In this paper, we have replaced direct correlation for computing the waveform inversion gradient by modified interferometric imaging, which enhances the continuity of the imaging path and reduces noise interference. The new imaging condition is a weighted average of extended imaging gathers can be directly used in the gradient computation. In this process, we have not changed the objective function, and the role of the imaging condition is similar to regularization. The window size for the modified interferometric imaging condition-based waveform inversion plays an important role in this process. The numerical examples show that the proposed method significantly enhances waveform inversion performance.
2. On the potential of OFDM enhancements as 5G waveforms
DEFF Research Database (Denmark)
Berardinelli, Gilberto; Pajukoski, Kari; Lähetkangas, Eeva
2014-01-01
The ideal radio waveform for an upcoming 5th Generation (5G) radio access technology should cope with a set of requirements such as limited complexity, good time/frequency localization and simple extension to multi-antenna technologies. This paper discusses the suitability of Orthogonal Frequency...... Division Multiplexing (OFDM) and its recently proposed enhancements as 5G waveforms, mainly focusing on their capability to cope with our requirements. Significant focus is given to the novel zero-tail paradigm, which allows boosting the OFDM flexibility while circumventing demerits such as poor spectral...
3. Waveform and packet structure of lion roars
Directory of Open Access Journals (Sweden)
W. Baumjohann
Full Text Available The Equator-S magnetometer is very sensitive and has a sampling rate of normally 128 Hz. The high sampling rate allows for the first time fluxgate magnetometer measurements of ELF waves between the ion cyclotron and the lower hybrid frequencies in the equatorial dayside magnetosheath. The so-called lion roars, typically seen by the Equator-S magnetometer at the bottom of the magnetic troughs of magnetosheath mirror waves, are near-monochromatic packets of electron whistler waves lasting for a few wave cycles only, typically 0.25 s. They are right-hand circularly polarized waves with typical amplitudes of 0.5–1 nT at around one tenth of the electron gyrofrequency. The cone angle between wave vector and ambient field is usually smaller than 1.5°.
Key words. Interplanetary physics (MHD waves and turbulence; plasma waves and turbulence
4. Waveform and packet structure of lion roars
Directory of Open Access Journals (Sweden)
W. Baumjohann
1999-12-01
Full Text Available The Equator-S magnetometer is very sensitive and has a sampling rate of normally 128 Hz. The high sampling rate allows for the first time fluxgate magnetometer measurements of ELF waves between the ion cyclotron and the lower hybrid frequencies in the equatorial dayside magnetosheath. The so-called lion roars, typically seen by the Equator-S magnetometer at the bottom of the magnetic troughs of magnetosheath mirror waves, are near-monochromatic packets of electron whistler waves lasting for a few wave cycles only, typically 0.25 s. They are right-hand circularly polarized waves with typical amplitudes of 0.5–1 nT at around one tenth of the electron gyrofrequency. The cone angle between wave vector and ambient field is usually smaller than 1.5°.Key words. Interplanetary physics (MHD waves and turbulence; plasma waves and turbulence
5. Scaling of cross-sections for asymmetric (e, 3e) process on helium ...
An approximate simple scaling law is obtained for asymmetric (, 3) process on helium-like ions for double ionization by fast electrons. It is based on the equation ( Z ′ 3 / ) exp [ − Z ′ ( r 1 + r 2 ) ] , Z ′ = Z − ( 5 / 16 ) for ground state wave function of helium- like ions and Z ′ 2 scaling of energies. The scaling law is ...
6. Scaling of triple differential cross-sections for asymmetric (e, 2e ...
A simple scaling law is obtained for asymmetric (, 2) process on helium isoelectronic ions by fast electrons. It is based on treating the targets as having one active electron moving in the effective Coulomb field of the atomic core with an effective charge ' = − 5/8. This effective charge is also used in the description of ...
7. Synthesis method of asymmetric gold particles.
Science.gov (United States)
Jun, Bong-Hyun; Murata, Michael; Hahm, Eunil; Lee, Luke P
2017-06-07
Asymmetric particles can exhibit unique properties. However, reported synthesis methods for asymmetric particles hinder their application because these methods have a limited scale and lack the ability to afford particles of varied shapes. Herein, we report a novel synthetic method which has the potential to produce large quantities of asymmetric particles. Asymmetric rose-shaped gold particles were fabricated as a proof of concept experiment. First, silica nanoparticles (NPs) were bound to a hydrophobic micro-sized polymer containing 2-chlorotritylchloride linkers (2-CTC resin). Then, half-planar gold particles with rose-shaped and polyhedral structures were prepared on the silica particles on the 2-CTC resin. Particle size was controlled by the concentration of the gold source. The asymmetric particles were easily cleaved from the resin without aggregation. We confirmed that gold was grown on the silica NPs. This facile method for synthesizing asymmetric particles has great potential for materials science.
8. LG tools for asymmetric wargaming
Science.gov (United States)
Stilman, Boris; Yakhnis, Alex; Yakhnis, Vladimir
2002-07-01
Asymmetric operations represent conflict where one of the sides would apply military power to influence the political and civil environment, to facilitate diplomacy, and to interrupt specified illegal activities. This is a special type of conflict where the participants do not initiate full-scale war. Instead, the sides may be engaged in a limited open conflict or one or several sides may covertly engage another side using unconventional or less conventional methods of engagement. They may include peace operations, combating terrorism, counterdrug operations, arms control, support of insurgencies or counterinsurgencies, show of force. An asymmetric conflict can be represented as several concurrent interlinked games of various kinds: military, transportation, economic, political, etc. Thus, various actions of peace violators, terrorists, drug traffickers, etc., can be expressed via moves in different interlinked games. LG tools allow us to fully capture the specificity of asymmetric conflicts employing the major LG concept of hypergame. Hypergame allows modeling concurrent interlinked processes taking place in geographically remote locations at different levels of resolution and time scale. For example, it allows us to model an antiterrorist operation taking place simultaneously in a number of countries around the globe and involving wide range of entities from individuals to combat units to governments. Additionally, LG allows us to model all sides of the conflict at their level of sophistication. Intelligent stakeholders are represented by means of LG generated intelligent strategies. TO generate those strategies, in addition to its own mathematical intelligence, the LG algorithm may incorporate the intelligence of the top-level experts in the respective problem domains. LG models the individual differences between intelligent stakeholders. The LG tools make it possible to incorporate most of the known traits of a stakeholder, i.e., real personalities involved in
9. Incompressibility of asymmetric nuclear matter
International Nuclear Information System (INIS)
Chen, Liewen; Cai, Baojun; Shen, Chun; Ko, Cheming; Xu, Jun; Li, Baoan
2010-01-01
Using an isospin- and momentum-dependent modified Gogny (MDI) interaction, the Skyrme-Hartree-Fock (SHF) approach, and a phenomenological modified Skyrme-like (MSL) model, we have studied the incompressibility K sat (δ) of isospin asymmetric nuclear matter at its saturation density. Our results show that in the expansion of K sat (δ) in powers of isospin asymmetry δ, i.e., K sat (δ) = K 0 + K sat,2 δ 2 + K sat,4 δ 4 + O(δ 6 ), the magnitude of the 4th-order K sat,4 parameter is generally small. The 2nd-order K sat,2 parameter thus essentially characterizes the isospin dependence of the incompressibility of asymmetric nuclear matter at saturation density. Furthermore, the K sat,2 can be expressed as K sat,2 = K sym – 6L – J 0 /K 0 L in terms of the slope parameter L and the curvature parameter K sym of the symmetry energy and the third-order derivative parameter J 0 of the energy of symmetric nuclear matter at saturation density, and we find the higher order J 0 contribution to K sat,2 generally cannot be neglected. Also, we have found a linear correlation between K sym and L as well as between J 0 /K 0 and K 0 . Using these correlations together with the empirical constraints on K 0 and L, the nuclear symmetry energy E sym (ρ0) at normal nuclear density, and the nucleon effective mass, we have obtained an estimated value of K sat,2 = -370 ± 120 MeV for the 2nd-order parameter in the isospin asymmetry expansion of the incompressibility of asymmetric nuclear matter at its saturation density. (author)
10. Asymmetric effects in customer satisfaction
DEFF Research Database (Denmark)
Füller, Johann; Matzler, Kurt; Faullant, Rita
2006-01-01
The results of this study on customer satisfaction in snowboard areas show that the relationship between an attribute and overall satisfaction can indeed be asymmetric. A 30-item self-administered survey was completed by snowboarders (n=2526) in 51 areas in Austria, Germany, Switzerland and Italy....... Results show that waiting time is a dissatisfier; it has a significant impact on overall customer satisfaction in the low satisfaction condition and becomes insignificant in the high satisfaction situation. Restaurants and bars are hybrids, i.e. importance does not depend on performance. Slopes, fun...
11. Asymmetric Formal Synthesis of Azadirachtin.
Science.gov (United States)
Mori, Naoki; Kitahara, Takeshi; Mori, Kenji; Watanabe, Hidenori
2015-12-01
An asymmetric formal synthesis of azadirachtin, a potent insect antifeedant, was accomplished in 30 steps to Ley's synthetic intermediate (longest linear sequence). The synthesis features: 1) rapid access to the optically active right-hand segment starting from the known 5-hydroxymethyl-2-cyclopentenone scaffold; 2) construction of the B and E rings by a key intramolecular tandem radical cyclization; 3) formation of the hemiacetal moiety in the C ring through the α-oxidation of the six-membered lactone followed by methanolysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
12. Spontaneous baryogenesis from asymmetric inflaton
International Nuclear Information System (INIS)
Takahashi, Fuminobu
2015-10-01
We propose a variant scenario of spontaneous baryogenesis from asymmetric inflaton based on current-current interactions between the inflaton and matter fields with a non-zero B-L charge. When the inflaton starts to oscillate around the minimum after inflation, it may lead to excitation of a CP-odd component, which induces an effective chemical potential for the B-L number through the current-current interactions. We study concrete inflation models and show that the spontaneous baryogenesis scenario can be naturally implemented in the chaotic inflation in supergravity.
13. Asymmetric Flexible MXene-Reduced Graphene Oxide Micro-Supercapacitor
KAUST Repository
Couly, Cedric
2017-11-27
Current microfabrication of micro-supercapacitors often involves multistep processing and delicate lithography protocols. In this study, simple fabrication of an asymmetric MXene-based micro-supercapacitor that is flexible, binder-free, and current-collector-free is reported. The interdigitated device architecture is fabricated using a custom-made mask and a scalable spray coating technique onto a flexible, transparent substrate. The electrode materials are comprised of titanium carbide MXene (Ti3C2Tx) and reduced graphene oxide (rGO), which are both 2D layered materials that contribute to the fast ion diffusion in the interdigitated electrode architecture. This MXene-based asymmetric micro-supercapacitor operates at a 1 V voltage window, while retaining 97% of the initial capacitance after ten thousand cycles, and exhibits an energy density of 8.6 mW h cm−3 at a power density of 0.2 W cm−3. Further, these micro-supercapacitors show a high level of flexibility during mechanical bending. Utilizing the ability of Ti3C2Tx-MXene electrodes to operate at negative potentials in aqueous electrolytes, it is shown that using Ti3C2Tx as a negative electrode and rGO as a positive one in asymmetric architectures is a promising strategy for increasing both energy and power densities of micro-supercapacitors.
14. Waveform Diversity and Design for Interoperating Radar Systems
Science.gov (United States)
2013-01-01
University Di Pisa Department Di Ingegneria Dell Informazione Elettronica, Informatica , Telecomunicazioni Via Girolamo Caruso 16 Pisa, Italy 56122...NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) University Di Pisa Department Di Ingegneria Dell Informazione Elettronica, Informatica ...DIPARTIMENTO DI INGEGNERIA DELL’INFORMAZIONE ELETTRONICA, INFORMATICA , TELECOMUNICAZIONI WAVEFORM DIVERSITY AND DESIGN FOR INTEROPERATING
NARCIS (Netherlands)
Haffinger, P.R.
2013-01-01
Full waveform inversion is a tool to obtain high-resolution property models of the subsurface from seismic data. However, the technique is computationally expens- ive and so far no multi-dimensional implementation exists to achieve a resolution that can directly be used for seismic interpretation
16. Augmented kludge waveforms for detecting extreme-mass-ratio inspirals
Science.gov (United States)
Chua, Alvin J. K.; Moore, Christopher J.; Gair, Jonathan R.
2017-08-01
The extreme-mass-ratio inspirals (EMRIs) of stellar-mass compact objects into massive black holes are an important class of source for the future space-based gravitational-wave detector LISA. Detecting signals from EMRIs will require waveform models that are both accurate and computationally efficient. In this paper, we present the latest implementation of an augmented analytic kludge (AAK) model, publicly available at https://github.com/alvincjk/EMRI_Kludge_Suite as part of an EMRI waveform software suite. This version of the AAK model has improved accuracy compared to its predecessors, with two-month waveform overlaps against a more accurate fiducial model exceeding 0.97 for a generic range of sources; it also generates waveforms 5-15 times faster than the fiducial model. The AAK model is well suited for scoping out data analysis issues in the upcoming round of mock LISA data challenges. A simple analytic argument shows that it might even be viable for detecting EMRIs with LISA through a semicoherent template bank method, while the use of the original analytic kludge in the same approach will result in around 90% fewer detections.
17. Centered Differential Waveform Inversion with Minimum Support Regularization
KAUST Repository
2017-05-26
Time-lapse full-waveform inversion has two major challenges. The first one is the reconstruction of a reference model (baseline model for most of approaches). The second is inversion for the time-lapse changes in the parameters. Common model approach is utilizing the information contained in all available data sets to build a better reference model for time lapse inversion. Differential (Double-difference) waveform inversion allows to reduce the artifacts introduced into estimates of time-lapse parameter changes by imperfect inversion for the baseline-reference model. We propose centered differential waveform inversion (CDWI) which combines these two approaches in order to benefit from both of their features. We apply minimum support regularization commonly used with electromagnetic methods of geophysical exploration. We test the CDWI method on synthetic dataset with random noise and show that, with Minimum support regularization, it provides better resolution of velocity changes than with total variation and Tikhonov regularizations in time-lapse full-waveform inversion.
18. Josephson Arbitrary Waveform Synthesis With Multilevel Pulse Biasing
Science.gov (United States)
Brevik, Justus A.; Flowers-Jacobs, Nathan E.; Fox, Anna E.; Golden, Evan B.; Dresselhaus, Paul D.; Benz, Samuel P.
2017-01-01
We describe the implementation of new commercial pulse-bias electronics that have enabled an improvement in the generation of quantum-accurate waveforms both with and without low-frequency compensation biases. We have used these electronics to apply a multilevel pulse bias to the Josephson arbitrary waveform synthesizer and have generated, for the first time, a quantum-accurate bipolar sinusoidal waveform without the use of a low-frequency compensation bias current. This uncompensated 1 kHz waveform was synthesized with an rms amplitude of 325 mV and maintained its quantum accuracy over a1.5 mA operating current range. The same technique and equipment was also used to synthesize a quantum-accurate 1 MHz sinusoid with a 1.2 mA operating margin. In addition, we have synthesized a compensated 1 kHz sinusoid with an rms amplitude of 1 V and a 2.7 mA operating margin. PMID:28736494
19. Synchronous Generator Model Parameter Estimation Based on Noisy Dynamic Waveforms
Science.gov (United States)
Berhausen, Sebastian; Paszek, Stefan
2016-01-01
In recent years, there have occurred system failures in many power systems all over the world. They have resulted in a lack of power supply to a large number of recipients. To minimize the risk of occurrence of power failures, it is necessary to perform multivariate investigations, including simulations, of power system operating conditions. To conduct reliable simulations, the current base of parameters of the models of generating units, containing the models of synchronous generators, is necessary. In the paper, there is presented a method for parameter estimation of a synchronous generator nonlinear model based on the analysis of selected transient waveforms caused by introducing a disturbance (in the form of a pseudorandom signal) in the generator voltage regulation channel. The parameter estimation was performed by minimizing the objective function defined as a mean square error for deviations between the measurement waveforms and the waveforms calculated based on the generator mathematical model. A hybrid algorithm was used for the minimization of the objective function. In the paper, there is described a filter system used for filtering the noisy measurement waveforms. The calculation results of the model of a 44 kW synchronous generator installed on a laboratory stand of the Institute of Electrical Engineering and Computer Science of the Silesian University of Technology are also given. The presented estimation method can be successfully applied to parameter estimation of different models of high-power synchronous generators operating in a power system.
20. Multisource waveform inversion of marine streamer data using normalized wavefield
KAUST Repository
Choi, Yun Seok
2013-09-01
Multisource full-waveform inversion based on the L1- and L2-norm objective functions cannot be applied to marine streamer data because it does not take into account the unmatched acquisition geometries between the observed and modeled data. To apply multisource full-waveform inversion to marine streamer data, we construct the L1- and L2-norm objective functions using the normalized wavefield. The new residual seismograms obtained from the L1- and L2-norms using the normalized wavefield mitigate the problem of unmatched acquisition geometries, which enables multisource full-waveform inversion to work with marine streamer data. In the new approaches using the normalized wavefield, we used the back-propagation algorithm based on the adjoint-state technique to efficiently calculate the gradients of the objective functions. Numerical examples showed that multisource full-waveform inversion using the normalized wavefield yields much better convergence for marine streamer data than conventional approaches. © 2013 Society of Exploration Geophysicists.
1. Centered Differential Waveform Inversion with Minimum Support Regularization
KAUST Repository
2017-01-01
Time-lapse full-waveform inversion has two major challenges. The first one is the reconstruction of a reference model (baseline model for most of approaches). The second is inversion for the time-lapse changes in the parameters. Common model
2. Frequency-domain waveform inversion using the phase derivative
KAUST Repository
Choi, Yun Seok; Alkhalifah, Tariq Ali
2013-01-01
Phase wrapping in the frequency domain or cycle skipping in the time domain is the major cause of the local minima problem in the waveform inversion when the starting model is far from the true model. Since the phase derivative does not suffer from
3. Experimental validation of waveform relaxation technique for power ...
damping controller drawn our attention to a potential convergence problem which ... method was originally proposed as a method of parallelizing the numerical integration of very. Figure 2 ..... to it the features of an industrial real-time operating system. ..... Odeh F and Ruehli A 1985 Waveform relaxation: Theory and practice.
4. MURI: Adaptive Waveform Design for Full Spectral Dominance
Science.gov (United States)
2011-03-11
perhaps in a similarly-named file in the same directory as the data file) and handled by a Java class with an API for a user to request data without the...1101- 1104 . [15] J. Wang, and A. Nehorai, “Adaptive polarimetry design for a target in compound-Gaussian clutter,” International Waveform Diversity and
5. Multisource waveform inversion of marine streamer data using normalized wavefield
KAUST Repository
Choi, Yun Seok; Alkhalifah, Tariq Ali
2013-01-01
Multisource full-waveform inversion based on the L1- and L2-norm objective functions cannot be applied to marine streamer data because it does not take into account the unmatched acquisition geometries between the observed and modeled data. To apply
6. Categorisation of full waveform data provided by laser scanning devices
Science.gov (United States)
Ullrich, Andreas; Pfennigbauer, Martin
2011-11-01
In 2004, a laser scanner device for commercial airborne laser scanning applications, the RIEGL LMS-Q560, was introduced to the market, making use of a radical alternative approach to the traditional analogue signal detection and processing schemes found in LIDAR instruments so far: digitizing the echo signals received by the instrument for every laser pulse and analysing these echo signals off-line in a so-called full waveform analysis in order to retrieve almost all information contained in the echo signal using transparent algorithms adaptable to specific applications. In the field of laser scanning the somewhat unspecific term "full waveform data" has since been established. We attempt a categorisation of the different types of the full waveform data found in the market. We discuss the challenges in echo digitization and waveform analysis from an instrument designer's point of view and we will address the benefits to be gained by using this technique, especially with respect to the so-called multi-target capability of pulsed time-of-flight LIDAR instruments.
7. A compact, multichannel, and low noise arbitrary waveform generator.
Science.gov (United States)
Govorkov, S; Ivanov, B I; Il'ichev, E; Meyer, H-G
2014-05-01
A new type of high functionality, fast, compact, and easy programmable arbitrary waveform generator for low noise physical measurements is presented. The generator provides 7 fast differential waveform channels with a maximum bandwidth up to 200 MHz frequency. There are 6 fast pulse generators on the generator board with 78 ps time resolution in both duration and delay, 3 of them with amplitude control. The arbitrary waveform generator is additionally equipped with two auxiliary slow 16 bit analog-to-digital converters and four 16 bit digital-to-analog converters for low frequency applications. Electromagnetic shields are introduced to the power supply, digital, and analog compartments and with a proper filter design perform more than 110 dB digital noise isolation to the output signals. All the output channels of the board have 50 Ω SubMiniature version A termination. The generator board is suitable for use as a part of a high sensitive physical equipment, e.g., fast read out and manipulation of nuclear magnetic resonance or superconducting quantum systems and any other application, which requires electromagnetic interference free fast pulse and arbitrary waveform generation.
8. A nonlinear approach of elastic reflection waveform inversion
KAUST Repository
Guo, Qiang
2016-09-06
Elastic full waveform inversion (EFWI) embodies the original intention of waveform inversion at its inception as it is a better representation of the mostly solid Earth. However, compared with the acoustic P-wave assumption, EFWI for P- and S-wave velocities using multi-component data admitted mixed results. Full waveform inversion (FWI) is a highly nonlinear problem and this nonlinearity only increases under the elastic assumption. Reflection waveform inversion (RWI) can mitigate the nonlinearity by relying on transmissions from reflections focused on inverting low wavenumber components of the model. In our elastic endeavor, we split the P- and S-wave velocities into low wavenumber and perturbation components and propose a nonlinear approach to invert for both of them. The new optimization problem is built on an objective function that depends on both background and perturbation models. We utilize an equivalent stress source based on the model perturbation to generate reflection instead of demigrating from an image, which is applied in conventional RWI. Application on a slice of an ocean-bottom data shows that our method can efficiently update the low wavenumber parts of the model, but more so, obtain perturbations that can be added to the low wavenumbers for a high resolution output.
9. A compact, multichannel, and low noise arbitrary waveform generator
International Nuclear Information System (INIS)
Govorkov, S.; Ivanov, B. I.; Il'ichev, E.; Meyer, H.-G.
2014-01-01
A new type of high functionality, fast, compact, and easy programmable arbitrary waveform generator for low noise physical measurements is presented. The generator provides 7 fast differential waveform channels with a maximum bandwidth up to 200 MHz frequency. There are 6 fast pulse generators on the generator board with 78 ps time resolution in both duration and delay, 3 of them with amplitude control. The arbitrary waveform generator is additionally equipped with two auxiliary slow 16 bit analog-to-digital converters and four 16 bit digital-to-analog converters for low frequency applications. Electromagnetic shields are introduced to the power supply, digital, and analog compartments and with a proper filter design perform more than 110 dB digital noise isolation to the output signals. All the output channels of the board have 50 Ω SubMiniature version A termination. The generator board is suitable for use as a part of a high sensitive physical equipment, e.g., fast read out and manipulation of nuclear magnetic resonance or superconducting quantum systems and any other application, which requires electromagnetic interference free fast pulse and arbitrary waveform generation
10. Programmable optical waveform reshaping on a picosecond timescale
DEFF Research Database (Denmark)
Manurkar, Paritosh; Jain, Nitin; Kumar Periyannan Rajeswari, Prem
2017-01-01
We experimentally demonstrate the temporal reshaping of optical waveforms in the telecom wavelength band using the principle of quantum frequency conversion. The reshaped optical pulses do not undergo any wavelength translation. The interaction takes place in a nonlinear chi((2)) waveguide using ...... for quantum communications. (C) 2017 Optical Society of America...
11. A nonlinear approach of elastic reflection waveform inversion
KAUST Repository
Guo, Qiang; Alkhalifah, Tariq Ali
2016-01-01
Elastic full waveform inversion (EFWI) embodies the original intention of waveform inversion at its inception as it is a better representation of the mostly solid Earth. However, compared with the acoustic P-wave assumption, EFWI for P- and S-wave velocities using multi-component data admitted mixed results. Full waveform inversion (FWI) is a highly nonlinear problem and this nonlinearity only increases under the elastic assumption. Reflection waveform inversion (RWI) can mitigate the nonlinearity by relying on transmissions from reflections focused on inverting low wavenumber components of the model. In our elastic endeavor, we split the P- and S-wave velocities into low wavenumber and perturbation components and propose a nonlinear approach to invert for both of them. The new optimization problem is built on an objective function that depends on both background and perturbation models. We utilize an equivalent stress source based on the model perturbation to generate reflection instead of demigrating from an image, which is applied in conventional RWI. Application on a slice of an ocean-bottom data shows that our method can efficiently update the low wavenumber parts of the model, but more so, obtain perturbations that can be added to the low wavenumbers for a high resolution output.
12. Field factors for asymmetric collimators
International Nuclear Information System (INIS)
Turner, J.R.; Butler, A.P.H.
1996-01-01
In recent years manufacturers have been supplying linear accelerators with either a single pair or a dual pair of collimators. The use of a model to relate off-axis field factors to on-axis field factors obviates the need for repeat measurements whenever the asymmetric collimators are employed. We have investigated the variation of collimator scatter Sc, with distance of the central ray x from the central axis for a variety of non square field sizes. Collimator scatter was measured by in-air measurements with a build-up cap. The Primaty-Off-Centre-Ratio (POCR) was measured in-air by scanning orthogonally across the beam with an ionization chamber. The result of the investigation is the useful prediction of off-axis field factors for a range of rectangular asymmetric fields using the simple product of the on-axis field factor and the POCR in air. The effect of asymmetry on the quality of the beam and hence the percent depth dose will be discussed. (author)
13. 2D acoustic-elastic coupled waveform inversion in the Laplace domain
KAUST Repository
Bae, Hoseuk; Shin, Changsoo; Cha, Youngho; Choi, Yun Seok; Min, Dongjoo
2010-01-01
Although waveform inversion has been intensively studied in an effort to properly delineate the Earth's structures since the early 1980s, most of the time- and frequency-domain waveform inversion algorithms still have critical limitations
14. Full waveform inversion based on scattering angle enrichment with application to real dataset
KAUST Repository
Wu, Zedong; Alkhalifah, Tariq Ali
2015-01-01
Reflected waveform inversion (RWI) provides a method to reduce the nonlinearity of the standard full waveform inversion (FWI). However, the drawback of the existing RWI methods is inability to utilize diving waves and the extra sensitivity
15. Analysis of LFM-waveform Libraries for Cognitive Tracking Maneuvering Targets
Directory of Open Access Journals (Sweden)
Wang Hongyan
2016-01-01
Full Text Available Based on the idea of the waveform agility in cognitive radars，the waveform libraries for maneuvering target tracking are discussed. LFM-waveform libraries are designed according to different combinations of chirp parameters and FrFT rotation angles. By applying the interact multiple model (IMM algorithm in tracking maneuvering targets, transmitted waveform is called real time from the LFM-waveform libraries. The waveforms are selected from the library according to the criterion of maximum mutual information between the current state of knowledge of the model and the measurement. Simulation results show that waveform library containing certain amount LFM-waveforms can improve the performance of cognitive tracking radar.
16. Ascending-ramp biphasic waveform has a lower defibrillation threshold and releases less troponin I than a truncated exponential biphasic waveform.
Science.gov (United States)
Huang, Jian; Walcott, Gregory P; Ruse, Richard B; Bohanan, Scott J; Killingsworth, Cheryl R; Ideker, Raymond E
2012-09-11
We tested the hypothesis that the shape of the shock waveform affects not only the defibrillation threshold but also the amount of cardiac damage. Defibrillation thresholds were determined for 11 waveforms-3 ascending-ramp waveforms, 3 descending-ramp waveforms, 3 rectilinear first-phase biphasic waveforms, a Gurvich waveform, and a truncated exponential biphasic waveform-in 6 pigs with electrodes in the right ventricular apex and superior vena cava. The ascending, descending, and rectilinear waveforms had 4-, 8-, and 16-millisecond first phases and a 3.5-millisecond rectilinear second phase that was half the voltage of the first phase. The exponential biphasic waveform had a 60% first-phase and a 50% second-phase tilt. In a second study, we attempted to defibrillate after 10 seconds of ventricular fibrillation with a single ≈30-J shock (6 pigs successfully defibrillated with 8-millisecond ascending, 8-millisecond rectilinear, and truncated exponential biphasic waveforms). Troponin I blood levels were determined before and 2 to 10 hours after the shock. The lowest-energy defibrillation threshold was for the 8-milliseconds ascending ramp (14.6±7.3 J [mean±SD]), which was significantly less than for the truncated exponential (19.6±6.3 J). Six hours after shock, troponin I was significantly less for the ascending-ramp waveform (0.80±0.54 ng/mL) than for the truncated exponential (1.92±0.47 ng/mL) or the rectilinear waveform (1.17±0.45 ng/mL). The ascending ramp has a significantly lower defibrillation threshold and at ≈30 J causes 58% less troponin I release than the truncated exponential biphasic shock. Therefore, the shock waveform affects both the defibrillation threshold and the amount of cardiac damage.
17. Method and device for ion mobility separations
Science.gov (United States)
Ibrahim, Yehia M.; Garimella, Sandilya V. B.; Smith, Richard D.
2017-07-11
Methods and devices for ion separations or manipulations in gas phase are disclosed. The device includes a single non-planar surface. Arrays of electrodes are coupled to the surface. A combination of RF and DC voltages are applied to the arrays of electrodes to create confining and driving fields that move ions through the device. The DC voltages are static DC voltages or time-dependent DC potentials or waveforms.
18. Microseismic event location by master-event waveform stacking
Science.gov (United States)
Grigoli, F.; Cesca, S.; Dahm, T.
2016-12-01
Waveform stacking location methods are nowadays extensively used to monitor induced seismicity monitoring assoiciated with several underground industrial activities such as Mining, Oil&Gas production and Geothermal energy exploitation. In the last decade a significant effort has been spent to develop or improve methodologies able to perform automated seismological analysis for weak events at a local scale. This effort was accompanied by the improvement of monitoring systems, resulting in an increasing number of large microseismicity catalogs. The analysis of microseismicity is challenging, because of the large number of recorded events often characterized by a low signal-to-noise ratio. A significant limitation of the traditional location approaches is that automated picking is often done on each seismogram individually, making little or no use of the coherency information between stations. In order to improve the performance of the traditional location methods, in the last year, alternative approaches have been proposed. These methods exploits the coherence of the waveforms recorded at different stations and do not require any automated picking procedure. The main advantage of this methods relies on their robustness even when the recorded waveforms are very noisy. On the other hand, like any other location method, the location performance strongly depends on the accuracy of the available velocity model. When dealing with inaccurate velocity models, in fact, location results can be affected by large errors. Here we will introduce a new automated waveform stacking location method which is less dependent on the knowledge of the velocity model and presents several benefits, which improve the location accuracy: 1) it accounts for phase delays due to local site effects, e.g. surface topography or variable sediment thickness 2) theoretical velocity model are only used to estimate travel times within the source volume, and not along the whole source-sensor path. We
19. Computer model analysis of the radial artery pressure waveform.
Science.gov (United States)
Schwid, H A; Taylor, L A; Smith, N T
1987-10-01
20. Effects of waveform model systematics on the interpretation of GW150914
OpenAIRE
Abbott, B. P.; Abbott, R.; Adhikari, R. X.; Ananyeva, A.; Anderson, S. B.; Appert, S.; Arai, K.; Araya, M. C.; Barayoga, J. C.; Barish, B. C.; Berger, B. K.; Billingsley, G.; Biscans, S; Blackburn, J. K.; Bork, R.
2017-01-01
Parameter estimates of GW150914 were obtained using Bayesian inference, based on three semi-analytic waveform models for binary black hole coalescences. These waveform models differ from each other in their treatment of black hole spins, and all three models make some simplifying assumptions, notably to neglect sub-dominant waveform harmonic modes and orbital eccentricity. Furthermore, while the models are calibrated to agree with waveforms obtained by full numerical solutions of Einstein's e...
1. A new optimization approach for source-encoding full-waveform inversion
NARCIS (Netherlands)
Moghaddam, P.P.; Keers, H.; Herrmann, F.J.; Mulder, W.A.
2013-01-01
Waveform inversion is the method of choice for determining a highly heterogeneous subsurface structure. However, conventional waveform inversion requires that the wavefield for each source is computed separately. This makes it very expensive for realistic 3D seismic surveys. Source-encoding waveform
2. Predicting Electrocardiogram and Arterial Blood Pressure Waveforms with Different Echo State Network Architectures
Science.gov (United States)
2014-11-01
Predicting Electrocardiogram and Arterial Blood Pressure Waveforms with Different Echo State Network Architectures Allan Fong, MS1,3, Ranjeev...the medical staff in Intensive Care Units. The ability to predict electrocardiogram and arterial blood pressure waveforms can potentially help the...type of neural network for mining, understanding, and predicting electrocardiogram and arterial blood pressure waveforms. Several network
3. Asymmetric Frontal Brain Activity and Parental Rejection
NARCIS (Netherlands)
Huffmeijer, R.; Alink, L.R.A.; Tops, M.; Bakermans-Kranenburg, M.J.; van IJzendoorn, M.H.
2013-01-01
Asymmetric frontal brain activity has been widely implicated in reactions to emotional stimuli and is thought to reflect individual differences in approach-withdrawal motivation. Here, we investigate whether asymmetric frontal activity, as a measure of approach-withdrawal motivation, also predicts
4. Worst Asymmetrical Short-Circuit Current
DEFF Research Database (Denmark)
Arana Aristi, Iván; Holmstrøm, O; Grastrup, L
2010-01-01
In a typical power plant, the production scenario and the short-circuit time were found for the worst asymmetrical short-circuit current. Then, a sensitivity analysis on the missing generator values was realized in order to minimize the uncertainty of the results. Afterward the worst asymmetrical...
5. Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach
Directory of Open Access Journals (Sweden)
Pankaj Chauhan
2012-12-01
Full Text Available Ball-milling and pestle and mortar grinding have emerged as powerful methods for the development of environmentally benign chemical transformations. Recently, the use of these mechanochemical techniques in asymmetric organocatalysis has increased. This review highlights the progress in asymmetric organocatalytic reactions assisted by mechanochemical techniques.
6. The Modularized Software Package ASKI - Full Waveform Inversion Based on Waveform Sensitivity Kernels Utilizing External Seismic Wave Propagation Codes
Science.gov (United States)
Schumacher, F.; Friederich, W.
2015-12-01
We present the modularized software package ASKI which is a flexible and extendable toolbox for seismic full waveform inversion (FWI) as well as sensitivity or resolution analysis operating on the sensitivity matrix. It utilizes established wave propagation codes for solving the forward problem and offers an alternative to the monolithic, unflexible and hard-to-modify codes that have typically been written for solving inverse problems. It is available under the GPL at www.rub.de/aski. The Gauss-Newton FWI method for 3D-heterogeneous elastic earth models is based on waveform sensitivity kernels and can be applied to inverse problems at various spatial scales in both Cartesian and spherical geometries. The kernels are derived in the frequency domain from Born scattering theory as the Fréchet derivatives of linearized full waveform data functionals, quantifying the influence of elastic earth model parameters on the particular waveform data values. As an important innovation, we keep two independent spatial descriptions of the earth model - one for solving the forward problem and one representing the inverted model updates. Thereby we account for the independent needs of spatial model resolution of forward and inverse problem, respectively. Due to pre-integration of the kernels over the (in general much coarser) inversion grid, storage requirements for the sensitivity kernels are dramatically reduced.ASKI can be flexibly extended to other forward codes by providing it with specific interface routines that contain knowledge about forward code-specific file formats and auxiliary information provided by the new forward code. In order to sustain flexibility, the ASKI tools must communicate via file output/input, thus large storage capacities need to be accessible in a convenient way. Storing the complete sensitivity matrix to file, however, permits the scientist full manual control over each step in a customized procedure of sensitivity/resolution analysis and full
7. Study of asymmetrical electric discharges using particle simulation
International Nuclear Information System (INIS)
Alves, M.V.
1990-11-01
Asymmetrical electric discharges are been widely used in the microelectronic industry. The asymmetry in the electrode areas determines the magnitude of the plasma-to-electrode voltage, V sub(a), at the powered electrode, which determines the ion bombarding energy, a critical plasma processing parameter. Two many-particle simulation codes, called P D C 1 and P D S 1, were developed. These codes are electrostatic, one-dimensional (radial) and model (a bounded plasma between two infinite cylinders or two concentric spheres that can be connected to a RLC external circuit. Both codes consider asymmetrical electrodes areas. In order to simulate electrical discharges, Monte-Carlo simulation of electron-neutral and ion-neutral collisions were included. These codes were used to study the relationship between the voltage area ratio across the sheaths, V sub(a) / V sub(b), and the electrode area ratio A sub(b) / A sub(a). Simulation results agree with experimental results and also with the analytical model that includes local ionization near the electrodes, observed to occur in almost all our simulations. (author)
8. Designing asymmetric multiferroics with strong magnetoelectric coupling
Science.gov (United States)
Lu, Xuezeng; Xiang, Hongjun; Rondinelli, James; Materials Theory; Design Group Team
2015-03-01
Multiferroics offer exciting opportunities for electric-field control of magnetism. Single-phase multiferroics suitable for such applications at room temperature need much more study. Here, we propose the concept of an alternative type of multiferroics, namely, the asymmetric multiferroic.'' In asymmetric multiferroics, two locally stable ferroelectric states are not symmetrically equivalent, leading to different magnetic properties between these two states. Furthermore, we predict from first principles that a Fe-Cr-Mo superlattice with the LiNbO3-type structure is such an asymmetric multiferroic. The strong ferrimagnetism, high ferroelectric polarization, and significant dependence of the magnetic transition temperature on polarization make this asymmetric multiferroic an ideal candidate for realizing electric-field control of magnetism at room temperature. Our study suggests that the asymmetric multiferroic may provide an alternative playground for voltage control of magnetism and find its applications in spintronics and quantum computing.
9. Synthesis of sheath voltage drops in asymmetric radio-frequency discharges
International Nuclear Information System (INIS)
Yonemura, Shigeru; Nanbu, Kenichi; Iwata, Naoaki
2004-01-01
A sheath voltage drop in asymmetric discharges is one of the most important parameters of radio-frequency capacitively coupled plasmas because it determines the kinetic energy of the ions incident on the target or substrate. In this study, we developed a numerical simulation code to estimate the sheath voltage drops and, consequently, the self-bias voltage. We roughly approximated general asymmetric rf discharges to one-dimensional spherical ones. The results obtained by using our simulation code are consistent with measurements and Lieberman's theory
10. A case of asymmetrical arthrogryposis
International Nuclear Information System (INIS)
Hageman, G.; Vette, J.K.; Willemse, J.
1983-01-01
Following the introduction of the conception that arthrogryposis is a symptom and not a clinical entity, a case of the very rare asymmetric form of neurogenic arthrogryposis is presented. The asymmetry of congenital contractures and weakness is associated with hemihypotrophy. The value of muscular CT-scanning prior to muscle biopsy is demonstrated. Muscular CT-scanning shows the extension of adipose tissue, which has replaced damaged muscles and therby indicates the exact site for muscle biopsy. Since orthopaedic treatment in arthrogryposis can be unrewarding due to severe muscular degeneration, preoperative scanning may provide additional important information on muscular function and thus be of benefit for surgery. The advantage of muscular CT-scanning in other forms of arthrogryposis requires further determination. The differential diagnosis with Werdnig-Hoffmann disease is discussed. (author)
11. Comprehensive asymmetric dark matter model
Science.gov (United States)
Lonsdale, Stephen J.; Volkas, Raymond R.
2018-05-01
Asymmetric dark matter (ADM) is motivated by the similar cosmological mass densities measured for ordinary and dark matter. We present a comprehensive theory for ADM that addresses the mass density similarity, going beyond the usual ADM explanations of similar number densities. It features an explicit matter-antimatter asymmetry generation mechanism, has one fully worked out thermal history and suggestions for other possibilities, and meets all phenomenological, cosmological and astrophysical constraints. Importantly, it incorporates a deep reason for why the dark matter mass scale is related to the proton mass, a key consideration in ADM models. Our starting point is the idea of mirror matter, which offers an explanation for dark matter by duplicating the standard model with a dark sector related by a Z2 parity symmetry. However, the dark sector need not manifest as a symmetric copy of the standard model in the present day. By utilizing the mechanism of "asymmetric symmetry breaking" with two Higgs doublets in each sector, we develop a model of ADM where the mirror symmetry is spontaneously broken, leading to an electroweak scale in the dark sector that is significantly larger than that of the visible sector. The weak sensitivity of the ordinary and dark QCD confinement scales to their respective electroweak scales leads to the necessary connection between the dark matter and proton masses. The dark matter is composed of either dark neutrons or a mixture of dark neutrons and metastable dark hydrogen atoms. Lepton asymmetries are generated by the C P -violating decays of heavy Majorana neutrinos in both sectors. These are then converted by sphaleron processes to produce the observed ratio of visible to dark matter in the universe. The dynamics responsible for the kinetic decoupling of the two sectors emerges as an important issue that we only partially solve.
12. Analytic family of post-merger template waveforms
Science.gov (United States)
Del Pozzo, Walter; Nagar, Alessandro
2017-06-01
Building on the analytical description of the post-merger (ringdown) waveform of coalescing, nonprecessing, spinning binary black holes introduced by Damour and Nagar [Phys. Rev. D 90, 024054 (2014), 10.1103/PhysRevD.90.024054], we propose an analytic, closed form, time-domain, representation of the ℓ=m =2 gravitational radiation mode emitted after merger. This expression is given as a function of the component masses and dimensionless spins (m1 ,2,χ1 ,2) of the two inspiraling objects, as well as of the mass MBH and (complex) frequency σ1 of the fundamental quasinormal mode of the remnant black hole. Our proposed template is obtained by fitting the post-merger waveform part of several publicly available numerical relativity simulations from the Simulating eXtreme Spacetimes (SXS) catalog and then suitably interpolating over (symmetric) mass ratio and spins. We show that this analytic expression accurately reproduces (˜0.01 rad ) the phasing of the post-merger data of other data sets not used in its construction. This is notably the case of the spin-aligned run SXS:BBH:0305, whose intrinsic parameters are consistent with the 90% credible intervals reported in the parameter-estimation followup of GW150914 by B.P. Abbott et al. [Phys. Rev. Lett. 116, 241102 (2016), 10.1103/PhysRevLett.116.241102]. Using SXS waveforms as "experimental" data, we further show that our template could be used on the actual GW150914 data to perform a new measure of the complex frequency of the fundamental quasinormal mode so as to exploit the complete (high signal-to-noise-ratio) post-merger waveform. We assess the usefulness of our proposed template by analyzing, in a realistic setting, SXS full inspiral-merger-ringdown waveforms and constructing posterior probability distribution functions for the central frequency damping time of the first overtone of the fundamental quasinormal mode as well as for the physical parameters of the systems. We also briefly explore the possibility
13. Heavy residues from very mass asymmetric heavy ion reactions
International Nuclear Information System (INIS)
Hanold, K.A.
1994-08-01
The isotopic production cross sections and momenta of all residues with nuclear charge (Z) greater than 39 from the reaction of 26, 40, and 50 MeV/nucleon 129 Xe + Be, C, and Al were measured. The isotopic cross sections, the momentum distribution for each isotope, and the cross section as a function of nuclear charge and momentum are presented here. The new cross sections are consistent with previous measurements of the cross sections from similar reaction systems. The shape of the cross section distribution, when considered as a function of Z and velocity, was found to be qualitatively consistent with that expected from an incomplete fusion reaction mechanism. An incomplete fusion model coupled to a statistical decay model is able to reproduce many features of these reactions: the shapes of the elemental cross section distributions, the emission velocity distributions for the intermediate mass fragments, and the Z versus velocity distributions. This model gives a less satisfactory prediction of the momentum distribution for each isotope. A very different model based on the Boltzman-Nordheim-Vlasov equation and which was also coupled to a statistical decay model reproduces many features of these reactions: the shapes of the elemental cross section distributions, the intermediate mass fragment emission velocity distributions, and the Z versus momentum distributions. Both model calculations over-estimate the average mass for each element by two mass units and underestimate the isotopic and isobaric widths of the experimental distributions. It is shown that the predicted average mass for each element can be brought into agreement with the data by small, but systematic, variation of the particle emission barriers used in the statistical model. The predicted isotopic and isobaric widths of the cross section distributions can not be brought into agreement with the experimental data using reasonable parameters for the statistical model
14. Pulsed electric field sensor based on original waveform measurement
International Nuclear Information System (INIS)
Ma Liang; Wu Wei; Cheng Yinhui; Zhou Hui; Li Baozhong; Li Jinxi; Zhu Meng
2010-01-01
The paper introduces the differential and original waveform measurement principles for pulsed E-field, and develops an pulsed E-field sensor based on original waveform measurement along with its theoretical correction model. The sensor consists of antenna, integrator, amplifier and driver, optic-electric/electric-optic conversion module and transmission module. The time-domain calibration in TEM cell indicates that, its risetime response is shorter than 1.0 ns, and the output pulse width at 90% of the maximum amplitude is wider than 10.0 μs. The output amplitude of the sensor is linear to the electric field intensity in a dynamic range of 20 dB. The measurement capability can be extended to 10 V/m or 50 kV/m by changing the system's antenna and other relative modules. (authors)
15. A novel PMT test system based on waveform sampling
Science.gov (United States)
Yin, S.; Ma, L.; Ning, Z.; Qian, S.; Wang, Y.; Jiang, X.; Wang, Z.; Yu, B.; Gao, F.; Zhu, Y.; Wang, Z.
2018-01-01
Comparing with the traditional test system based on a QDC and TDC and scaler, a test system based on waveform sampling is constructed for signal sampling of the 8"R5912 and the 20"R12860 Hamamatsu PMT in different energy states from single to multiple photoelectrons. In order to achieve high throughput and to reduce the dead time in data processing, the data acquisition software based on LabVIEW is developed and runs with a parallel mechanism. The analysis algorithm is realized in LabVIEW and the spectra of charge, amplitude, signal width and rising time are analyzed offline. The results from Charge-to-Digital Converter, Time-to-Digital Converter and waveform sampling are discussed in detailed comparison.
16. Quantum optical arbitrary waveform manipulation and measurement in real time.
Science.gov (United States)
Kowligy, Abijith S; Manurkar, Paritosh; Corzo, Neil V; Velev, Vesselin G; Silver, Michael; Scott, Ryan P; Yoo, S J B; Kumar, Prem; Kanter, Gregory S; Huang, Yu-Ping
2014-11-17
We describe a technique for dynamic quantum optical arbitrary-waveform generation and manipulation, which is capable of mode selectively operating on quantum signals without inducing significant loss or decoherence. It is built upon combining the developed tools of quantum frequency conversion and optical arbitrary waveform generation. Considering realistic parameters, we propose and analyze applications such as programmable reshaping of picosecond-scale temporal modes, selective frequency conversion of any one or superposition of those modes, and mode-resolved photon counting. We also report on experimental progress to distinguish two overlapping, orthogonal temporal modes, demonstrating over 8 dB extinction between picosecond-scale time-frequency modes, which agrees well with our theory. Our theoretical and experimental progress, as a whole, points to an enabling optical technique for various applications such as ultradense quantum coding, unity-efficiency cavity-atom quantum memories, and high-speed quantum computing.
17. Transient waveform acquisition system for the ELMO Bumpy Torus
International Nuclear Information System (INIS)
Young, K.G.; Burris, R.D.; Hillis, D.H.; Overbey, D.R.
1984-10-01
The transient waveform system described in this report is designed to acquire analog waveforms from the ELMO Bumpy Torus (EBT) diagnostic experiments. Pressure, density, synchrotron radiation, etc., are acquired and digitized with a Kinetic Systems TR812 transient recorder and associated modules located in a CAMAC crate. The system can simultaneously acquire, display, and transmit sets of data consisting of identification parameters and up to 1024 data points for 1 to 64 input signals (frequency range = 0.01 pulse/s to 100 kHz) of data every one or more minutes; thus, it can run continuously without operator intervention. The data are taken on a VAX 11/780 and transmitted to a data base on a DECSystem-10. To aid the programmer in making future modifications to the system, detailed documentation using the Yourdon structural methods has been given
18. Metering error quantification under voltage and current waveform distortion
Science.gov (United States)
Wang, Tao; Wang, Jia; Xie, Zhi; Zhang, Ran
2017-09-01
With integration of more and more renewable energies and distortion loads into power grid, the voltage and current waveform distortion results in metering error in the smart meters. Because of the negative effects on the metering accuracy and fairness, it is an important subject to study energy metering combined error. In this paper, after the comparing between metering theoretical value and real recorded value under different meter modes for linear and nonlinear loads, a quantification method of metering mode error is proposed under waveform distortion. Based on the metering and time-division multiplier principles, a quantification method of metering accuracy error is proposed also. Analyzing the mode error and accuracy error, a comprehensive error analysis method is presented which is suitable for new energy and nonlinear loads. The proposed method has been proved by simulation.
19. Image-domain full waveform inversion: Field data example
KAUST Repository
Zhang, Sanzong
2014-08-05
The main difficulty with the data-domain full waveform inversion (FWI) is that it tends to get stuck in the local minima associated with the waveform misfit function. This is the result of cycle skipping which degrades the low-wavenumber update in the absence of low-frequencies and long-offset data. An image-domain objective function is defined as the normed difference between the predicted and observed common image gathers (CIGs) in the subsurface offset domain. This new objective function is not constrained by cycle skipping at the far subsurface offsets. To test the effectiveness of this method, we apply it to marine data recorded in the Gulf of Mexico. Results show that image-domain FWI is less sensitive to the initial model and the absence of low-frequency data compared with conventional FWI. The liability, however, is that it is almost an order of magnitude more expensive than standard FWI.
20. Photonic arbitrary waveform generation applicable to multiband UWB communications.
Science.gov (United States)
Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José
2010-12-06
A novel photonic structure for arbitrary waveform generation (AWG) is proposed based on the electrooptical intensity modulation of a broadband optical signal which is transmitted by a dispersive element and the optoelectrical processing is realized by combining an interferometric structure with balanced photodetection. The generated waveform can be fully reconfigured through the control of the optical source power spectrum and the interferometric structure. The use of balanced photodetection permits to remove the baseband component of the generated signal which is relevant in certain applications. We have theoretically described and experimentally demonstrated the feasibility of the system by means of the generation of different pulse shapes. Specifically, the proposed structure has been applicable to generate Multiband UWB signaling formats regarding to the FCC requirements in order to show the flexibility of the system.
1. Strategies for the characteristic extraction of gravitational waveforms
International Nuclear Information System (INIS)
Babiuc, M. C.; Bishop, N. T.; Szilagyi, B.; Winicour, J.
2009-01-01
We develop, test, and compare new numerical and geometrical methods for improving the accuracy of extracting waveforms using characteristic evolution. The new numerical method involves use of circular boundaries to the stereographic grid patches which cover the spherical cross sections of the outgoing null cones. We show how an angular version of numerical dissipation can be introduced into the characteristic code to damp the high frequency error arising form the irregular way the circular patch boundary cuts through the grid. The new geometric method involves use of the Weyl tensor component Ψ 4 to extract the waveform as opposed to the original approach via the Bondi news function. We develop the necessary analytic and computational formula to compute the O(1/r) radiative part of Ψ 4 in terms of a conformally compactified treatment of null infinity. These methods are compared and calibrated in test problems based upon linearized waves.
2. Image-domain full waveform inversion: Field data example
KAUST Repository
Zhang, Sanzong; Schuster, Gerard T.
2014-01-01
The main difficulty with the data-domain full waveform inversion (FWI) is that it tends to get stuck in the local minima associated with the waveform misfit function. This is the result of cycle skipping which degrades the low-wavenumber update in the absence of low-frequencies and long-offset data. An image-domain objective function is defined as the normed difference between the predicted and observed common image gathers (CIGs) in the subsurface offset domain. This new objective function is not constrained by cycle skipping at the far subsurface offsets. To test the effectiveness of this method, we apply it to marine data recorded in the Gulf of Mexico. Results show that image-domain FWI is less sensitive to the initial model and the absence of low-frequency data compared with conventional FWI. The liability, however, is that it is almost an order of magnitude more expensive than standard FWI.
3. Toward Generating More Diagnostic Features from Photoplethysmogram Waveforms
Directory of Open Access Journals (Sweden)
Mohamed Elgendi
2018-03-01
Full Text Available Photoplethysmogram (PPG signals collected using a pulse oximeter are increasingly being used for screening and diagnosis purposes. Because of the non-invasive, cost-effective, and easy-to-use nature of the pulse oximeter, clinicians and biomedical engineers are investigating how PPG signals can help in the management of many medical conditions, especially for global health application. The study of PPG signal analysis is relatively new compared to research in electrocardiogram signals, for instance; however, we anticipate that in the near future blood pressure, cardiac output, and other clinical parameters will be measured from wearable devices that collect PPG signals, based on the signal’s vast potential. This article attempts to organize and standardize the names of PPG waveforms to ensure consistent terminologies, thereby helping the rapid developments in this research area, decreasing the disconnect within and among different disciplines, and increasing the number of features generated from PPG waveforms.
4. Toward Generating More Diagnostic Features from Photoplethysmogram Waveforms.
Science.gov (United States)
Elgendi, Mohamed; Liang, Yongbo; Ward, Rabab
2018-03-11
Photoplethysmogram (PPG) signals collected using a pulse oximeter are increasingly being used for screening and diagnosis purposes. Because of the non-invasive, cost-effective, and easy-to-use nature of the pulse oximeter, clinicians and biomedical engineers are investigating how PPG signals can help in the management of many medical conditions, especially for global health application. The study of PPG signal analysis is relatively new compared to research in electrocardiogram signals, for instance; however, we anticipate that in the near future blood pressure, cardiac output, and other clinical parameters will be measured from wearable devices that collect PPG signals, based on the signal's vast potential. This article attempts to organize and standardize the names of PPG waveforms to ensure consistent terminologies, thereby helping the rapid developments in this research area, decreasing the disconnect within and among different disciplines, and increasing the number of features generated from PPG waveforms.
5. Temporal changes of the inner core from waveform doublets
Science.gov (United States)
Yang, Y.; Song, X.
2017-12-01
Temporal changes of the Earth's inner core have been detected from earthquake waveform doublets (repeating sources with similar waveforms at the same station). Using doublets from events up to the present in the South Sandwich Island (SSI) region recorded by the station COLA (Alaska), we confirmed systematic temporal variations in the travel time of the inner-core-refracted phase (PKIKP, the DF branch). The DF phase arrives increasingly earlier than outer core phases (BC and AB) by rate of approximately 0.07 s per decade since 1970s. If we assume that the temporal change is caused by a shift of the lateral gradient from the inner core rotation as in previous studies, we estimate the rotation rate of 0.2-0.4 degree per year. We also analyzed the topography of the inner core boundary (ICB) using SSI waveform doublets recorded by seismic stations in Eurasia and North America with reflected phase (PKiKP) and refracted phases. There are clear temporal changes in the waveforms of doublets for PKiKP under Africa and Central America. In addition, for doublets recorded by three nearby stations (AAK, AML, and UCH), we observed systematic change in the relative travel time of PKiKP and PKIKP. The temporal change of the (PKiKP - PKIKP) differential time is always negative for the event pairs if both events are before 2007, while it fluctuates to positive if the later event occurs after 2007. The rapid temporal changes in space and time may indicate localized processes (e.g., freezing and melting) of the ICB in the recent decades under Africa. We are exploring 4D models consistent with the temporal changes.
6. Frequency-Dependent Blanking with Digital Linear Chirp Waveform Synthesis
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Andrews, John M. [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States)
2014-07-01
Wideband radar systems, especially those that operate at lower frequencies such as VHF and UHF, are often restricted from transmitting within or across specific frequency bands in order to prevent interference to other spectrum users. Herein we describe techniques for notching the transmitted spectrum of a generated and transmitted radar waveform. The notches are fully programmable as to their location, and techniques are given that control the characteristics of the notches.
7. Arbitrary waveform generator to improve laser diode driver performance
Science.gov (United States)
Fulkerson, Jr, Edward Steven
2015-11-03
An arbitrary waveform generator modifies the input signal to a laser diode driver circuit in order to reduce the overshoot/undershoot and provide a "flat-top" signal to the laser diode driver circuit. The input signal is modified based on the original received signal and the feedback from the laser diode by measuring the actual current flowing in the laser diode after the original signal is applied to the laser diode.
8. Acquisition of L2 Japanese Geminates: Training with Waveform Displays
Science.gov (United States)
Motohashi-Saigo, Miki; Hardison, Debra M.
2009-01-01
The value of waveform displays as visual feedback was explored in a training study involving perception and production of L2 Japanese by beginning-level L1 English learners. A pretest-posttest design compared auditory-visual (AV) and auditory-only (A-only) Web-based training. Stimuli were singleton and geminate /t,k,s/ followed by /a,u/ in two…
CERN Document Server
Gini, Fulvio
2012-01-01
In recent years, various algorithms for radar signal design, that rely heavily upon complicated processing and/or antenna architectures, have been suggested. These techniques owe their genesis to several factors, including revolutionary technological advances (new flexible waveform generators, high speed signal processing hardware, digital array radar technology, etc.) and the stressing performance requirements, often imposed by defence applications in areas such as airborne early warning and homeland security.Increasingly complex operating scenarios calls for sophisticated algorithms with the
10. DISECA - A Matlab code for dispersive waveform calculations
Czech Academy of Sciences Publication Activity Database
Gaždová, Renata; Vilhelm, J.
2011-01-01
Roč. 38, č. 4 (2011), s. 526-531 ISSN 0266-352X R&D Projects: GA AV ČR IAA300460705 Institutional research plan: CEZ:AV0Z30460519 Keywords : velocity dispersion * synthetic waveform * seismic method Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.987, year: 2011 http://www.sciencedirect.com/science/article/pii/S0266352X11000425
11. Faithful effective-one-body waveforms of small-mass-ratio coalescing black hole binaries
International Nuclear Information System (INIS)
Damour, Thibault; Nagar, Alessandro
2007-01-01
We address the problem of constructing high-accuracy, faithful analytic waveforms describing the gravitational wave signal emitted by inspiralling and coalescing binary black holes. We work within the effective-one-body (EOB) framework and propose a methodology for improving the current (waveform) implementations of this framework based on understanding, element by element, the physics behind each feature of the waveform and on systematically comparing various EOB-based waveforms with exact waveforms obtained by numerical relativity approaches. The present paper focuses on small-mass-ratio nonspinning binary systems, which can be conveniently studied by Regge-Wheeler-Zerilli-type methods. Our results include (i) a resummed, 3 PN-accurate description of the inspiral waveform, (ii) a better description of radiation reaction during the plunge, (iii) a refined analytic expression for the plunge waveform, (iv) an improved treatment of the matching between the plunge and ring-down waveforms. This improved implementation of the EOB approach allows us to construct complete analytic waveforms which exhibit a remarkable agreement with the exact ones in modulus, frequency, and phase. In particular, the analytic and numerical waveforms stay in phase, during the whole process, within ±1.1% of a cycle. We expect that the extension of our methodology to the comparable-mass case will be able to generate comparably accurate analytic waveforms of direct use for the ground-based network of interferometric detectors of gravitational waves
12. Rapidly reconfigurable high-fidelity optical arbitrary waveform generation in heterogeneous photonic integrated circuits.
Science.gov (United States)
Feng, Shaoqi; Qin, Chuan; Shang, Kuanping; Pathak, Shibnath; Lai, Weicheng; Guan, Binbin; Clements, Matthew; Su, Tiehui; Liu, Guangyao; Lu, Hongbo; Scott, Ryan P; Ben Yoo, S J
2017-04-17
This paper demonstrates rapidly reconfigurable, high-fidelity optical arbitrary waveform generation (OAWG) in a heterogeneous photonic integrated circuit (PIC). The heterogeneous PIC combines advantages of high-speed indium phosphide (InP) modulators and low-loss, high-contrast silicon nitride (Si3N4) arrayed waveguide gratings (AWGs) so that high-fidelity optical waveform syntheses with rapid waveform updates are possible. The generated optical waveforms spanned a 160 GHz spectral bandwidth starting from an optical frequency comb consisting of eight comb lines separated by 20 GHz channel spacing. The Error Vector Magnitude (EVM) values of the generated waveforms were approximately 16.4%. The OAWG module can rapidly and arbitrarily reconfigure waveforms upon every pulse arriving at 2 ns repetition time. The result of this work indicates the feasibility of truly dynamic optical arbitrary waveform generation where the reconfiguration rate or the modulator bandwidth must exceed the channel spacing of the AWG and the optical frequency comb.
13. Gravitational Waveforms in the Early Inspiral of Binary Black Hole Systems
Science.gov (United States)
Barkett, Kevin; Kumar, Prayush; Bhagwat, Swetha; Brown, Duncan; Scheel, Mark; Szilagyi, Bela; Simulating eXtreme Spacetimes Collaboration
2015-04-01
The inspiral, merger and ringdown of compact object binaries are important targets for gravitational wave detection by aLIGO. Detection and parameter estimation will require long, accurate waveforms for comparison. There are a number of analytical models for generating gravitational waveforms for these systems, but the only way to ensure their consistency and correctness is by comparing with numerical relativity simulations that cover many inspiral orbits. We've simulated a number of binary black hole systems with mass ratio 7 and a moderate, aligned spin on the larger black hole. We have attached these numerical waveforms to analytical waveform models to generate long hybrid gravitational waveforms that span the entire aLIGO frequency band. We analyze the robustness of these hybrid waveforms and measure the faithfulness of different hybrids with each other to obtain an estimate on how long future numerical simulations need to be in order to ensure that waveforms are accurate enough for use by aLIGO.
14. Single-spin precessing gravitational waveform in closed form
Science.gov (United States)
Lundgren, Andrew; O'Shaughnessy, R.
2014-02-01
In coming years, gravitational-wave detectors should find black hole-neutron star (BH-NS) binaries, potentially coincident with astronomical phenomena like short gamma ray bursts. These binaries are expected to precess. Gravitational-wave science requires a tractable model for precessing binaries, to disentangle precession physics from other phenomena like modified strong field gravity, tidal deformability, or Hubble flow; and to measure compact object masses, spins, and alignments. Moreover, current searches for gravitational waves from compact binaries use templates where the binary does not precess and are ill-suited for detection of generic precessing sources. In this paper we provide a closed-form representation of the single-spin precessing waveform in the frequency domain by reorganizing the signal as a sum over harmonics, each of which resembles a nonprecessing waveform. This form enables simple analytic calculations of the Fisher matrix for use in template bank generation and coincidence metrics, and jump proposals to improve the efficiency of Markov chain Monte Carlo sampling. We have verified that for generic BH-NS binaries, our model agrees with the time-domain waveform to 2%. Straightforward extensions of the derivations outlined here (and provided in full online) allow higher accuracy and error estimates.
15. Photoplethysmographic signal waveform index for detection of increased arterial stiffness
International Nuclear Information System (INIS)
Pilt, K; Meigas, K; Ferenets, R; Temitski, K; Viigimaa, M
2014-01-01
The aim of this research was to assess the validity of the photoplethysmographic (PPG) waveform index PPGAI for the estimation of increased arterial stiffness. For this purpose, PPG signals were recorded from 24 healthy subjects and from 20 type II diabetes patients. The recorded PPG signals were processed with the analysis algorithm developed and the waveform index PPGAI similar to the augmentation index (AIx) was calculated. As a reference, the aortic AIx was assessed and normalized for a heart rate of 75 bpm (AIx@75) by a SphygmoCor device. A strong correlation (r = 0.85) between the PPGAI and the aortic AIx@75 and a positive correlation of both indices with age were found. Age corrections for the indices PPGAI and AIx@75 as regression models from the signals of healthy subjects were constructed. Both indices revealed a significant difference between the groups of diabetes patients and healthy controls. However, the PPGAI provided the best statistical discrimination for the group of subjects with increased arterial stiffness. The waveform index PPGAI based on the inexpensive PPG technology can be considered as a perspective measure of increased arterial stiffness estimation in clinical screenings. (paper)
16. Waveform inversion for acoustic VTI media in frequency domain
KAUST Repository
Wu, Zedong
2016-09-06
Reflected waveform inversion (RWI) provides a method to reduce the nonlinearity of the standard full waveform inversion (FWI) by inverting for the background model using a single scattered wavefield from an inverted perturbation. However, current RWI methods are mostly based on isotropic media assumption. We extend the idea of the combining inversion for the background model and perturbations to address transversely isotropic with a vertical axis of symmetry (VTI) media taking into consideration of the optimal parameter sensitivity information. As a result, we apply Born modeling corresponding to perturbations in only for the variable e to derive the relative reflected waveform inversion formulation. To reduce the number of parameters, we assume the background part of η = ε and work with a single variable to describe the anisotropic part of the wave propagation. Thus, the optimization variables are the horizontal velocity v, η = ε and the e perturbation. Application to the anisotropic version of Marmousi model with a single frequency of 2.5 Hz shows that this method can converge to the accurate result starting from a linearly increasing isotropic initial velocity. Application to a real dataset demonstrates the versatility of the approach.
17. Frequency-domain waveform inversion using the phase derivative
KAUST Repository
Choi, Yun Seok
2013-09-26
Phase wrapping in the frequency domain or cycle skipping in the time domain is the major cause of the local minima problem in the waveform inversion when the starting model is far from the true model. Since the phase derivative does not suffer from the wrapping effect, its inversion has the potential of providing a robust and reliable inversion result. We propose a new waveform inversion algorithm using the phase derivative in the frequency domain along with the exponential damping term to attenuate reflections. We estimate the phase derivative, or what we refer to as the instantaneous traveltime, by taking the derivative of the Fourier-transformed wavefield with respect to the angular frequency, dividing it by the wavefield itself and taking the imaginary part. The objective function is constructed using the phase derivative and the gradient of the objective function is computed using the back-propagation algorithm. Numerical examples show that our inversion algorithm with a strong damping generates a tomographic result even for a high ‘single’ frequency, which can be a good initial model for full waveform inversion and migration.
18. Nonspinning numerical relativity waveform surrogates: assessing the model
Science.gov (United States)
Field, Scott; Blackman, Jonathan; Galley, Chad; Scheel, Mark; Szilagyi, Bela; Tiglio, Manuel
2015-04-01
Recently, multi-modal gravitational waveform surrogate models have been built directly from data numerically generated by the Spectral Einstein Code (SpEC). I will describe ways in which the surrogate model error can be quantified. This task, in turn, requires (i) characterizing differences between waveforms computed by SpEC with those predicted by the surrogate model and (ii) estimating errors associated with the SpEC waveforms from which the surrogate is built. Both pieces can have numerous sources of numerical and systematic errors. We make an attempt to study the most dominant error sources and, ultimately, the surrogate model's fidelity. These investigations yield information about the surrogate model's uncertainty as a function of time (or frequency) and parameter, and could be useful in parameter estimation studies which seek to incorporate model error. Finally, I will conclude by comparing the numerical relativity surrogate model to other inspiral-merger-ringdown models. A companion talk will cover the building of multi-modal surrogate models.
19. Arbitrary waveform modulated pulse EPR at 200 GHz
Science.gov (United States)
Kaminker, Ilia; Barnes, Ryan; Han, Songi
2017-06-01
We report here on the implementation of arbitrary waveform generation (AWG) capabilities at ∼200 GHz into an Electron Paramagnetic Resonance (EPR) and Dynamic Nuclear Polarization (DNP) instrument platform operating at 7 T. This is achieved with the integration of a 1 GHz, 2 channel, digital to analog converter (DAC) board that enables the generation of coherent arbitrary waveforms at Ku-band frequencies with 1 ns resolution into an existing architecture of a solid state amplifier multiplier chain (AMC). This allows for the generation of arbitrary phase- and amplitude-modulated waveforms at 200 GHz with >150 mW power. We find that the non-linearity of the AMC poses significant difficulties in generating amplitude-modulated pulses at 200 GHz. We demonstrate that in the power-limited regime of ω1 10 MHz) spin manipulation in incoherent (inversion), as well as coherent (echo formation) experiments. Highlights include the improvement by one order of magnitude in inversion bandwidth compared to that of conventional rectangular pulses, as well as a factor of two in improvement in the refocused echo intensity at 200 GHz.
20. Chaos of several typical asymmetric systems
International Nuclear Information System (INIS)
Feng Jingjing; Zhang Qichang; Wang Wei
2012-01-01
The threshold for the onset of chaos in asymmetric nonlinear dynamic systems can be determined using an extended Padé method. In this paper, a double-well asymmetric potential system with damping under external periodic excitation is investigated, as well as an asymmetric triple-well potential system under external and parametric excitation. The integrals of Melnikov functions are established to demonstrate that the motion is chaotic. Threshold values are acquired when homoclinic and heteroclinic bifurcations occur. The results of analytical and numerical integration are compared to verify the effectiveness and feasibility of the analytical method.
1. Modelling asymmetric growth in crowded plant communities
DEFF Research Database (Denmark)
Damgaard, Christian
2010-01-01
A class of models that may be used to quantify the effect of size-asymmetric competition in crowded plant communities by estimating a community specific degree of size-asymmetric growth for each species in the community is suggested. The model consists of two parts: an individual size......-asymmetric growth part, where growth is assumed to be proportional to a power function of the size of the individual, and a term that reduces the relative growth rate as a decreasing function of the individual plant size and the competitive interactions from other plants in the neighbourhood....
2. Plasma and Energetic Particle Behaviors During Asymmetric Magnetic Reconnection at the Magnetopause
Science.gov (United States)
Lee, S. H.; Zhang, H.; Zong, Q.-G.; Otto, A.; Sibeck, D. G.; Wang, Y.; Glassmeier, K.-H.; Daly, P.W.; Reme, H.
2014-01-01
The factors controlling asymmetric reconnection and the role of the cold plasma population in the reconnection process are two outstanding questions. We present a case study of multipoint Cluster observations demonstrating that the separatrix and flow boundary angles are greater on the magnetosheath than on the magnetospheric side of the magnetopause, probably due to the stronger density than magnetic field asymmetry at this boundary. The motion of cold plasmaspheric ions entering the reconnection region differs from that of warmer magnetosheath and magnetospheric ions. In contrast to the warmer ions, which are probably accelerated by reconnection in the diffusion region near the subsolar magnetopause, the colder ions are simply entrained by ??×?? drifts at high latitudes on the recently reconnected magnetic field lines. This indicates that plasmaspheric ions can sometimes play only a very limited role in asymmetric reconnection, in contrast to previous simulation studies. Three cold ion populations (probably H+, He+, and O+) appear in the energy spectrum, consistent with ion acceleration to a common velocity.
3. Colocated MIMO Radar: Beamforming, Waveform design, and Target Parameter Estimation
KAUST Repository
Jardak, Seifallah
2014-04-01
Thanks to its improved capabilities, the Multiple Input Multiple Output (MIMO) radar is attracting the attention of researchers and practitioners alike. Because it transmits orthogonal or partially correlated waveforms, this emerging technology outperformed the phased array radar by providing better parametric identifiability, achieving higher spatial resolution, and designing complex beampatterns. To avoid jamming and enhance the signal to noise ratio, it is often interesting to maximize the transmitted power in a given region of interest and minimize it elsewhere. This problem is known as the transmit beampattern design and is usually tackled as a two-step process: a transmit covariance matrix is firstly designed by minimizing a convex optimization problem, which is then used to generate practical waveforms. In this work, we propose simple novel methods to generate correlated waveforms using finite alphabet constant and non-constant-envelope symbols. To generate finite alphabet waveforms, the proposed method maps easily generated Gaussian random variables onto the phase-shift-keying, pulse-amplitude, and quadrature-amplitude modulation schemes. For such mapping, the probability density function of Gaussian random variables is divided into M regions, where M is the number of alphabets in the corresponding modulation scheme. By exploiting the mapping function, the relationship between the cross-correlation of Gaussian and finite alphabet symbols is derived. The second part of this thesis covers the topic of target parameter estimation. To determine the reflection coefficient, spatial location, and Doppler shift of a target, maximum likelihood estimation yields the best performance. However, it requires a two dimensional search problem. Therefore, its computational complexity is prohibitively high. So, we proposed a reduced complexity and optimum performance algorithm which allows the two dimensional fast Fourier transform to jointly estimate the spatial location
4. Implementation of a quasi-realtime display of DIII-D neutral beam heating waveforms
International Nuclear Information System (INIS)
Phillips, J.C.
1993-10-01
The DIII-D neutral beam system employs eight 80 keV ion sources mounted on four beamlines to provide plasma heating to the DIII-D tokamak. The neutral beam system is capable of injecting over 20 MW of deuterium power with flexibility in terms of timing and modulation of the individual neutral beams. To maintain DIII-D's efficient tokamak shot cycle and make informed control decisions, it is important to be able to determine which beams fired, and exactly when, by the time the tokamak shot is over. Previously this information was available in centralized form only after a several minute wait. A cost-effective alternative to the traditional eight-channel storage oscilloscope has been implemented using off the shelf PC hardware and software. The system provides a real time display of injected neutral beam accelerator voltages and tokamak plasma current, as well an a summation waveform indicative of the total injected power as a function of time. The hardware consists of a Macintosh Centris 650 PC with a Motorola 68040 microprocessor. Data acquisition is accomplished using a National Instrument's 16-channel analog to digital conversion board for the Macintosh. The color displays and functionality were developed using National Instruments' LabView environment. Because the price of PCs has been decreasing rapidly and their capabilities increasing, this system is far less expensive than an eight-channel storage oscilloscope. As a flexible combination of PC and software, the system also provides much more capability than a dedicated oscilloscope, acting as the neutral beam coordinator's logbook, recording comments and availability statistics. Data such as shot number and neutral beam parameters are obtained over the local network from other computers and added to the display. Waveforms are easily archived to disk for future recall. Details of the implementation will be discussed along with samples of the displays and a description of the system's function and capabilities
5. Implementation of a quasi-realtime display of DIII-D neutral beam heating waveforms
Energy Technology Data Exchange (ETDEWEB)
Phillips, J.C.
1993-10-01
The DIII-D neutral beam system employs eight 80 keV ion sources mounted on four beamlines to provide plasma heating to the DIII-D tokamak. The neutral beam system is capable of injecting over 20 MW of deuterium power with flexibility in terms of timing and modulation of the individual neutral beams. To maintain DIII-Ds efficient tokamak shot cycle and make informed control decisions, it is important to be able to determine which beams fired, and exactly when, by the time the tokamak shot is over. Previously this information was available in centralized form only after a several minute wait. A cost-effective alternative to the traditional eight-channel storage oscilloscope has been implemented using off the shelf PC hardware and software. The system provides a real time display of injected neutral beam accelerator voltages and tokamak plasma current, as well an a summation waveform indicative of the total injected power as a function of time. The hardware consists of a Macintosh Centris 650 PC with a Motorola 68040 microprocessor. Data acquisition is accomplished using a National Instruments 16-channel analog to digital conversion board for the Macintosh. The color displays and functionality were developed using National Instruments LabView environment. Because the price of PCs has been decreasing rapidly and their capabilities increasing, this system is far less expensive than an eight-channel storage oscilloscope. As a flexible combination of PC and software, the system also provides much more capability than a dedicated oscilloscope, acting as the neutral beam coordinators logbook, recording comments and availability statistics. Data such as shot number and neutral beam parameters are obtained over the local network from other computers and added to the display. Waveforms are easily archived to disk for future recall. Details of the implementation will be discussed along with samples of the displays and a description of the systems function and capabilities.
6. Onboard software of Plasma Wave Experiment aboard Arase: instrument management and signal processing of Waveform Capture/Onboard Frequency Analyzer
Science.gov (United States)
Matsuda, Shoya; Kasahara, Yoshiya; Kojima, Hirotsugu; Kasaba, Yasumasa; Yagitani, Satoshi; Ozaki, Mitsunori; Imachi, Tomohiko; Ishisaka, Keigo; Kumamoto, Atsushi; Tsuchiya, Fuminori; Ota, Mamoru; Kurita, Satoshi; Miyoshi, Yoshizumi; Hikishima, Mitsuru; Matsuoka, Ayako; Shinohara, Iku
2018-05-01
We developed the onboard processing software for the Plasma Wave Experiment (PWE) onboard the Exploration of energization and Radiation in Geospace, Arase satellite. The PWE instrument has three receivers: Electric Field Detector, Waveform Capture/Onboard Frequency Analyzer (WFC/OFA), and the High-Frequency Analyzer. We designed a pseudo-parallel processing scheme with a time-sharing system and achieved simultaneous signal processing for each receiver. Since electric and magnetic field signals are processed by the different CPUs, we developed a synchronized observation system by using shared packets on the mission network. The OFA continuously measures the power spectra, spectral matrices, and complex spectra. The OFA obtains not only the entire ELF/VLF plasma waves' activity but also the detailed properties (e.g., propagation direction and polarization) of the observed plasma waves. We performed simultaneous observation of electric and magnetic field data and successfully obtained clear wave properties of whistler-mode chorus waves using these data. In order to measure raw waveforms, we developed two modes for the WFC, chorus burst mode' (65,536 samples/s) and EMIC burst mode' (1024 samples/s), for the purpose of the measurement of the whistler-mode chorus waves (typically in a frequency range from several hundred Hz to several kHz) and the EMIC waves (typically in a frequency range from a few Hz to several hundred Hz), respectively. We successfully obtained the waveforms of electric and magnetic fields of whistler-mode chorus waves and ion cyclotron mode waves along the Arase's orbit. We also designed the software-type wave-particle interaction analyzer mode. In this mode, we measure electric and magnetic field waveforms continuously and transfer them to the mission data recorder onboard the Arase satellite. We also installed an onboard signal calibration function (onboard SoftWare CALibration; SWCAL). We performed onboard electric circuit diagnostics and
7. Modeling of asymmetrical boost converters
Directory of Open Access Journals (Sweden)
Eliana Isabel Arango Zuluaga
2014-01-01
Full Text Available The asymmetrical interleaved dual boost (AIDB is a fifth-order DC/DC converter designed to interface photovoltaic (PV panels. The AIDB produces small current harmonics to the PV panels, reducing the power losses caused by the converter operation. Moreover, the AIDB provides a large voltage conversion ratio, which is required to step-up the PV voltage to the large dc-link voltage used in grid-connected inverters. To reject irradiance and load disturbances, the AIDB must be operated in a closed-loop and a dynamic model is required. Given that the AIDB converter operates in Discontinuous Conduction Mode (DCM, classical modeling approaches based on Continuous Conduction Mode (CCM are not valid. Moreover, classical DCM modeling techniques are not suitable for the AIDB converter. Therefore, this paper develops a novel mathematical model for the AIDB converter, which is suitable for control-pur-poses. The proposed model is based on the calculation of a diode current that is typically disregarded. Moreover, because the traditional correction to the second duty cycle reported in literature is not effective, a new equation is designed. The model accuracy is contrasted with circuital simulations in time and frequency domains, obtaining satisfactory results. Finally, the usefulness of the model in control applications is illustrated with an application example.
8. Asymmetric Supercapacitor Electrodes and Devices.
Science.gov (United States)
Choudhary, Nitin; Li, Chao; Moore, Julian; Nagaiah, Narasimha; Zhai, Lei; Jung, Yeonwoong; Thomas, Jayan
2017-06-01
The world is recently witnessing an explosive development of novel electronic and optoelectronic devices that demand more-reliable power sources that combine higher energy density and longer-term durability. Supercapacitors have become one of the most promising energy-storage systems, as they present multifold advantages of high power density, fast charging-discharging, and long cyclic stability. However, the intrinsically low energy density inherent to traditional supercapacitors severely limits their widespread applications, triggering researchers to explore new types of supercapacitors with improved performance. Asymmetric supercapacitors (ASCs) assembled using two dissimilar electrode materials offer a distinct advantage of wide operational voltage window, and thereby significantly enhance the energy density. Recent progress made in the field of ASCs is critically reviewed, with the main focus on an extensive survey of the materials developed for ASC electrodes, as well as covering the progress made in the fabrication of ASC devices over the last few decades. Current challenges and a future outlook of the field of ASCs are also discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
9. Bioinspired smart asymmetric nanochannel membranes.
Science.gov (United States)
Zhang, Zhen; Wen, Liping; Jiang, Lei
2018-01-22
Bioinspired smart asymmetric nanochannel membranes (BSANM) have been explored extensively to achieve the delicate ionic transport functions comparable to those of living organisms. The abiotic system exhibits superior stability and robustness, allowing for promising applications in many fields. In view of the abundance of research concerning BSANM in the past decade, herein, we present a systematic overview of the development of the state-of-the-art BSANM system. The discussion is focused on the construction methodologies based on raw materials with diverse dimensions (i.e. 0D, 1D, 2D, and bulk). A generic strategy for the design and construction of the BSANM system is proposed first and put into context with recent developments from homogeneous to heterogeneous nanochannel membranes. Then, the basic properties of the BSANM are introduced including selectivity, gating, and rectification, which are associated with the particular chemical and physical structures. Moreover, we summarized the practical applications of BSANM in energy conversion, biochemical sensing and other areas. In the end, some personal opinions on the future development of the BSANM are briefly illustrated. This review covers most of the related literature reported since 2010 and is intended to build up a broad and deep knowledge base that can provide a solid information source for the scientific community.
10. Reflection asymmetric shapes in nuclei
International Nuclear Information System (INIS)
Ahmad, I.; Carpenter, M.P.; Emling, H.
1989-01-01
Experimental data show that there is no even-even nucleus with a reflection asymmetric shape in its ground state. Maximum octupole- octupole correlations occur in nuclei in the mass 224 (N∼134, Z∼88) region. Parity doublets, which are the characteristic signature of octupole deformation, have been observed in several odd mass Ra, Ac and Pa nuclei. Intertwined negative and positive parity levels have been observed in several even-even Ra and Th nuclei above spin ∼8ℎ. In both cases, the opposite parity states are connected by fast El transitions. In some medium-mass nuclei intertwined negative and positive parity levels have also been observed above spin ∼7ℎ. The nuclei which exhibit octupole deformation in this mass region are 144 Ba, 146 Ba and 146 Ce; 142 Ba, 148 Ce, 150 Ce and 142 Xe do not show these characteristics. No case of parity doublet has been observed in the mass 144 region. 32 refs., 16 figs., 1 tab
11. Twin Higgs Asymmetric Dark Matter.
Science.gov (United States)
García García, Isabel; Lasenby, Robert; March-Russell, John
2015-09-18
We study asymmetric dark matter (ADM) in the context of the minimal (fraternal) twin Higgs solution to the little hierarchy problem, with a twin sector with gauged SU(3)^{'}×SU(2)^{'}, a twin Higgs doublet, and only third-generation twin fermions. Naturalness requires the QCD^{'} scale Λ_{QCD}^{'}≃0.5-20 GeV, and that t^{'} is heavy. We focus on the light b^{'} quark regime, m_{b^{'}}≲Λ_{QCD}^{'}, where QCD^{'} is characterized by a single scale Λ_{QCD}^{'} with no light pions. A twin baryon number asymmetry leads to a successful dark matter (DM) candidate: the spin-3/2 twin baryon, Δ^{'}∼b^{'}b^{'}b^{'}, with a dynamically determined mass (∼5Λ_{QCD}^{'}) in the preferred range for the DM-to-baryon ratio Ω_{DM}/Ω_{baryon}≃5. Gauging the U(1)^{'} group leads to twin atoms (Δ^{'}-τ^{'}[over ¯] bound states) that are successful ADM candidates in significant regions of parameter space, sometimes with observable changes to DM halo properties. Direct detection signatures satisfy current bounds, at times modified by dark form factors.
12. Lift production through asymmetric flapping
Science.gov (United States)
Jalikop, Shreyas; Sreenivas, K. R.
2009-11-01
At present, there is a strong interest in developing Micro Air Vehicles (MAV) for applications like disaster management and aerial surveys. At these small length scales, the flight of insects and small birds suggests that unsteady aerodynamics of flapping wings can offer many advantages over fixed wing flight, such as hovering-flight, high maneuverability and high lift at large angles of attack. Various lift generating mechanims such as delayed stall, wake capture and wing rotation contribute towards our understanding of insect flight. We address the effect of asymmetric flapping of wings on lift production. By visualising the flow around a pair of rectangular wings flapping in a water tank and numerically computing the flow using a discrete vortex method, we demonstrate that net lift can be produced by introducing an asymmetry in the upstroke-to-downstroke velocity profile of the flapping wings. The competition between generation of upstroke and downstroke tip vortices appears to hold the key to understanding this lift generation mechanism.
13. An efficient catalyst for asymmetric Reformatsky reaction
rate enantioselectivity using N,N-dialkylnorephedrines as chiral ligands. ..... temperatures also, there was no product conversion. ... Optimization of reaction conditions for asymmetric Reformatsky reaction between benzaldehyde and α-.
14. Asymmetric cryptography based on wavefront sensing.
Science.gov (United States)
Peng, Xiang; Wei, Hengzheng; Zhang, Peng
2006-12-15
A system of asymmetric cryptography based on wavefront sensing (ACWS) is proposed for the first time to our knowledge. One of the most significant features of the asymmetric cryptography is that a trapdoor one-way function is required and constructed by analogy to wavefront sensing, in which the public key may be derived from optical parameters, such as the wavelength or the focal length, while the private key may be obtained from a kind of regular point array. The ciphertext is generated by the encoded wavefront and represented with an irregular array. In such an ACWS system, the encryption key is not identical to the decryption key, which is another important feature of an asymmetric cryptographic system. The processes of asymmetric encryption and decryption are formulized mathematically and demonstrated with a set of numerical experiments.
15. Asymmetrical Representation of Gender in Amharic1
African Journals Online (AJOL)
in its grammar. Gender representation in this language is asymmetrical heavily ..... In dictionaries where. Amharic appears either as the target or the source language, verbs are entered ...... The Dialects of Amharic Revisited. Semitica et.
16. Beam-beam issues in asymmetric colliders
International Nuclear Information System (INIS)
Furman, M.A.
1992-07-01
We discuss generic beam-beam issues for proposed asymmetric e + - e - colliders. We illustrate the issues by choosing, as examples, the proposals by Cornell University (CESR-B), KEK, and SLAC/LBL/LLNL (PEP-II)
17. Congenital asymmetric crying face: a case report
Directory of Open Access Journals (Sweden)
Semra Kara
2011-12-01
Full Text Available Congenital asymmetric crying face is an anomalia caused by unilateral absence or weakness of depressor anguli oris muscle The major finding of the disease is the absence or weakness in the outer and lower movement of the commissure during crying. The other expression muscles are normal and the face is symmetric at rest. The asymmetry in congenital asymmetric crying face is most evident during infancy but decreases by age. Congenital asymmetric crying face can be associated with cervicofacial, musclebone, respiratory, genitourinary and central nervous system anomalia. It is diagnosed by physical examination. This paper presents a six days old infant with Congenital asymmetric crying face and discusses the case in terms of diagnosis and disease features.
Science.gov (United States)
Zheng, Huaiji; Zhao, Changgui; Fang, Bowen; Jing, Peng; Yang, Juan; Xie, Xingang; She, Xuegong
2012-07-06
The first asymmetric total syntheses of cladosporin and isocladosporin were accomplished in 8 steps with 8% overall yield and 10 steps with 26% overall yield, respectively. The relative configuration of isocladosporin was determined via this total synthesis.
19. Magnetically Modified Asymmetric Supercapacitors, Phase I
Data.gov (United States)
National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project is for the development of an asymmetric supercapacitor that will have improved energy density and cycle life....
20. Impact of Secondary Interactions in Asymmetric Catalysis
OpenAIRE
Frölander, Anders
2007-01-01
This thesis deals with secondary interactions in asymmetric catalysis and their impact on the outcome of catalytic reactions. The first part revolves around the metal-catalyzed asymmetric allylic alkylation reaction and how interactions within the catalyst affect the stereochemistry. An OH–Pd hydrogen bond in Pd(0)–π-olefin complexes of hydroxy-containing oxazoline ligands was identified by density functional theory computations and helped to rationalize the contrasting results obtained emplo...
1. Engineered Asymmetric Composite Membranes with Rectifying Properties.
Science.gov (United States)
Wen, Liping; Xiao, Kai; Sainath, Annadanam V Sesha; Komura, Motonori; Kong, Xiang-Yu; Xie, Ganhua; Zhang, Zhen; Tian, Ye; Iyoda, Tomokazu; Jiang, Lei
2016-01-27
Asymmetric composite membranes with rectifying properties are developed by grafting pH-stimulus-responsive materials onto the top layer of the composite structure, which is prepared by two novel block copolymers using a phase-separation technique. This engineered asymmetric composite membrane shows potential applications in sensors, filtration, and nanofluidic devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
2. Electron heating and energy inventory during asymmetric reconnection in a laboratory plasma
Science.gov (United States)
Yoo, J.; Na, B.; Jara-Almonte, J.; Yamada, M.; Ji, H.; Roytershteyn, V.; Argall, M. R.; Fox, W.; Chen, L. J.
2017-12-01
Electron heating and the energy inventory during asymmetric reconnection are studied in the Magnetic Reconnection Experiment (MRX) [1]. In this plasma, the density ratio is about 8 across the current sheet. Typical features of asymmetric reconnection such as the large density gradients near the low-density-side separatrices, asymmetric in-plane electric field, and bipolar out-of-plane magnetic field are observed. Unlike the symmetric case [2], electrons are also heated near the low-density-side separatrices. The measured parallel electric field may explain the observed electron heating. Although large fluctuations driven by lower-hybrid drift instabilities are also observed near the low-density-side separatrices, laboratory measurements and numerical simulations reported here suggest that they do not play a major role in electron energization. The average electron temperature increase in the exhaust region is proportional to the incoming magnetic energy per an electron/ion pair but exceeds the scaling of the previous space observations [3]. This discrepancy is explained by differences in the boundary condition and system size. The profile of electron energy gain from the electric field shows that there is additional electron energy gain associated with the electron diamagnetic current besides a large energy gain near the X-line. This additional energy gain increases electron enthalpy, not the electron temperature. Finally, a quantitative analysis of the energy inventory during asymmetric reconnection is conducted. Unlike the symmetric case where the ion energy gain is about twice more than the electron energy gain [4], electrons and ions obtain a similar amount of energy during asymmetric reconnection. [1] J. Yoo et al., accepted for a publication in J. Geophys. Res. [2] J. Yoo et al., Phys. Plasmas 21, 055706 (2014). [3] T. Phan et al., Geophys. Res. Lett. 40, 4475 (2013). [4] M. Yamada et al., Nat. Comms. 5, 4474 (2014).
3. Full-waveform data for building roof step edge localization
Science.gov (United States)
Słota, Małgorzata
2015-08-01
4. Determine Earthquake Rupture Directivity Using Taiwan TSMIP Strong Motion Waveforms
Science.gov (United States)
Chang, Kaiwen; Chi, Wu-Cheng; Lai, Ying-Ju; Gung, YuanCheng
2013-04-01
Inverting seismic waveforms for the finite fault source parameters is important for studying the physics of earthquake rupture processes. It is also significant to image seismogenic structures in urban areas. Here we analyze the finite-source process and test for the causative fault plane using the accelerograms recorded by the Taiwan Strong-Motion Instrumentation Program (TSMIP) stations. The point source parameters for the mainshock and aftershocks were first obtained by complete waveform moment tensor inversions. We then use the seismograms generated by the aftershocks as empirical Green's functions (EGFs) to retrieve the apparent source time functions (ASTFs) of near-field stations using projected Landweber deconvolution approach. The method for identifying the fault plane relies on the spatial patterns of the apparent source time function durations which depend on the angle between rupture direction and the take-off angle and azimuth of the ray. These derived duration patterns then are compared with the theoretical patterns, which are functions of the following parameters, including focal depth, epicentral distance, average crustal 1D velocity, fault plane attitude, and rupture direction on the fault plane. As a result, the ASTFs derived from EGFs can be used to infer the ruptured fault plane and the rupture direction. Finally we used part of the catalogs to study important seismogenic structures in the area near Chiayi, Taiwan, where a damaging earthquake has occurred about a century ago. The preliminary results show a strike-slip earthquake on 22 October 1999 (Mw 5.6) has ruptured unilaterally toward SSW on a sub-vertical fault. The procedure developed from this study can be applied to other strong motion waveforms recorded from other earthquakes to better understand their kinematic source parameters.
5. Development of optoelectronic monitoring system for ear arterial pressure waveforms
Science.gov (United States)
Sasayama, Satoshi; Imachi, Yu; Yagi, Tamotsu; Imachi, Kou; Ono, Toshirou; Man-i, Masando
1994-02-01
Invasive intra-arterial blood pressure measurement is the most accurate method but not practical if the subject is in motion. The apparatus developed by Wesseling et al., based on a volume-clamp method of Penaz (Finapres), is able to monitor continuous finger arterial pressure waveforms noninvasively. The limitation of Finapres is the difficulty in measuring the pressure of a subject during work that involves finger or arm action. Because the Finapres detector is attached to subject's finger, the measurements are affected by inertia of blood and hydrostatic effect cause by arm or finger motion. To overcome this problem, the authors made a detector that is attached to subject's ear and developed and optoelectronic monitoring systems for ear arterial pressure waveform (Earpres). An IR LEDs, photodiode, and air cuff comprised the detector. The detector was attached to a subject's ear, and the space adjusted between the air cuff and the rubber plate on which the LED and photodiode were positioned. To evaluate the accuracy of Earpres, the following tests were conducted with participation of 10 healthy male volunteers. The subjects rested for about five minutes, then performed standing and squatting exercises to provide wide ranges of systolic and diastolic arterial pressure. Intra- and inter-individual standard errors were calculated according to the method of van Egmond et al. As a result, average, the averages of intra-individual standard errors for earpres appeared small (3.7 and 2.7 mmHg for systolic and diastolic pressure respectively). The inter-individual standard errors for Earpres were about the same was Finapres for both systolic and diastolic pressure. The results showed the ear monitor was reliable in measuring arterial blood pressure waveforms and might be applicable to various fields such as sports medicine and ergonomics.
6. Improved gravitational waveforms from spinning black hole binaries
International Nuclear Information System (INIS)
Porter, Edward K.; Sathyaprakash, B.S.
2005-01-01
The standard post-Newtonian approximation to gravitational waveforms, called T-approximants, from nonspinning black hole binaries are known not to be sufficiently accurate close to the last stable orbit of the system. A new approximation, called P-approximants, is believed to improve the accuracy of the waveforms rendering them applicable up to the last stable orbit. In this study we apply P-approximants to the case of a test particle in equatorial orbit around a Kerr black hole parameterized by a spin-parameter q that takes values between -1 and 1. In order to assess the performance of the two approximants we measure their effectualness (i.e., larger overlaps with the exact signal), and faithfulness (i.e., smaller biases while measuring the parameters of the signal) with the exact (numerical) waveforms. We find that in the case of prograde orbits, that is orbits whose angular momentum is in the same sense as the spin angular momentum of the black hole, T-approximant templates obtain an effectualness of ∼0.99 for spins q 0.99 for all spins up to q=0.95. The bias in the estimation of parameters is much lower in the case of P-approximants than T-approximants. We find that P-approximants are both effectual and faithful and should be more effective than T-approximants as a detection template family when q>0. For q<0 both T- and P-approximants perform equally well so that either of them could be used as a detection template family
7. Asymmetric switching in a homodimeric ABC transporter: a simulation study.
Directory of Open Access Journals (Sweden)
Jussi Aittoniemi
2010-04-01
Full Text Available ABC transporters are a large family of membrane proteins involved in a variety of cellular processes, including multidrug and tumor resistance and ion channel regulation. Advances in the structural and functional understanding of ABC transporters have revealed that hydrolysis at the two canonical nucleotide-binding sites (NBSs is co-operative and non-simultaneous. A conserved core architecture of bacterial and eukaryotic ABC exporters has been established, as exemplified by the crystal structure of the homodimeric multidrug exporter Sav1866. Currently, it is unclear how sequential ATP hydrolysis arises in a symmetric homodimeric transporter, since it implies at least transient asymmetry at the NBSs. We show by molecular dynamics simulation that the initially symmetric structure of Sav1866 readily undergoes asymmetric transitions at its NBSs in a pre-hydrolytic nucleotide configuration. MgATP-binding residues and a network of charged residues at the dimer interface are shown to form a sequence of putative molecular switches that allow ATP hydrolysis only at one NBS. We extend our findings to eukaryotic ABC exporters which often consist of two non-identical half-transporters, frequently with degeneracy substitutions at one of their two NBSs. Interestingly, many residues involved in asymmetric conformational switching in Sav1866 are substituted in degenerate eukaryotic NBS. This finding strengthens recent suggestions that the interplay of a consensus and a degenerate NBS in eukaroytic ABC proteins pre-determines the sequence of hydrolysis at the two NBSs.
8. Interferometric full-waveform inversion of time-lapse data
KAUST Repository
Sinha, Mrinal
2017-08-17
One of the key challenges associated with time-lapse surveys is ensuring the repeatability between the baseline and monitor surveys. Non-repeatability between the surveys is caused by varying environmental conditions over the course of different surveys. To overcome this challenge, we propose the use of interferometric full waveform inversion (IFWI) for inverting the velocity model from data recorded by baseline and monitor surveys. A known reflector is used as the reference reflector for IFWI, and the data are naturally redatumed to this reference reflector using natural reflections as the redatuming operator. This natural redatuming mitigates the artifacts introduced by the repeatability errors that originate above the reference reflector.
9. Optimal control of photoelectron emission by realistic waveforms
Czech Academy of Sciences Publication Activity Database
Solanpää, J.; Ciappina, Marcelo F.; Räsänen, J.
2017-01-01
Roč. 64, č. 17 (2017), s. 1784-1792 ISSN 0950-0340 R&D Projects: GA MŠk EF15_008/0000162; GA MŠk LQ1606 Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:68378271 Keywords : above-threshold ionization * optimal control * waveforms Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 1.328, year: 2016
10. Ultrafast chirped optical waveform recorder using a time microscope
Science.gov (United States)
Bennett, Corey Vincent
2015-04-21
A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.
11. Plasma density calculation based on the HCN waveform data
International Nuclear Information System (INIS)
Chen Liaoyuan; Pan Li; Luo Cuiwen; Zhou Yan; Deng Zhongchao
2004-01-01
A method to improve the plasma density calculation is introduced using the base voltage and the phase zero points obtained from the HCN interference waveform data. The method includes making the signal quality higher by putting the signal control device and the analog-to-digit converters in the same location and charging them by the same power, and excluding the noise's effect according to the possible changing rate of the signal's phase, and to make the base voltage more accurate by dynamical data processing. (authors)
12. Frequency domain, waveform inversion of laboratory crosswell radar data
Science.gov (United States)
Ellefsen, Karl J.; Mazzella, Aldo T.; Horton, Robert J.; McKenna, Jason R.
2010-01-01
A new waveform inversion for crosswell radar is formulated in the frequency-domain for a 2.5D model. The inversion simulates radar waves using the vector Helmholtz equation for electromagnetic waves. The objective function is minimized using a backpropagation method suitable for a 2.5D model. The inversion is tested by processing crosswell radar data collected in a laboratory tank. The estimated model is consistent with the known electromagnetic properties of the tank. The formulation for the 2.5D model can be extended to inversions of acoustic and elastic data.
13. Complete waveform model for compact binaries on eccentric orbits
Science.gov (United States)
Huerta, E. A.; Kumar, Prayush; Agarwal, Bhanu; George, Daniel; Schive, Hsi-Yu; Pfeiffer, Harald P.; Haas, Roland; Ren, Wei; Chu, Tony; Boyle, Michael; Hemberger, Daniel A.; Kidder, Lawrence E.; Scheel, Mark A.; Szilagyi, Bela
2017-01-01
We present a time domain waveform model that describes the inspiral, merger and ringdown of compact binary systems whose components are nonspinning, and which evolve on orbits with low to moderate eccentricity. The inspiral evolution is described using third-order post-Newtonian equations both for the equations of motion of the binary, and its far-zone radiation field. This latter component also includes instantaneous, tails and tails-of-tails contributions, and a contribution due to nonlinear memory. This framework reduces to the post-Newtonian approximant TaylorT4 at third post-Newtonian order in the zero-eccentricity limit. To improve phase accuracy, we also incorporate higher-order post-Newtonian corrections for the energy flux of quasicircular binaries and gravitational self-force corrections to the binding energy of compact binaries. This enhanced prescription for the inspiral evolution is combined with a fully analytical prescription for the merger-ringdown evolution constructed using a catalog of numerical relativity simulations. We show that this inspiral-merger-ringdown waveform model reproduces the effective-one-body model of Ref. [Y. Pan et al., Phys. Rev. D 89, 061501 (2014)., 10.1103/PhysRevD.89.061501] for quasicircular black hole binaries with mass ratios between 1 to 15 in the zero-eccentricity limit over a wide range of the parameter space under consideration. Using a set of eccentric numerical relativity simulations, not used during calibration, we show that our new eccentric model reproduces the true features of eccentric compact binary coalescence throughout merger. We use this model to show that the gravitational-wave transients GW150914 and GW151226 can be effectively recovered with template banks of quasicircular, spin-aligned waveforms if the eccentricity e0 of these systems when they enter the aLIGO band at a gravitational-wave frequency of 14 Hz satisfies e0GW 150914≤0.15 and e0GW 151226≤0.1 . We also find that varying the spin
14. Sinusoidal oscillators and waveform generators using modern electronic circuit building blocks
CERN Document Server
Senani, Raj; Singh, V K; Sharma, R K
2016-01-01
This book serves as a single-source reference to sinusoidal oscillators and waveform generators, using classical as well as a variety of modern electronic circuit building blocks. It provides a state-of-the-art review of a large variety of sinusoidal oscillators and waveform generators and includes a catalogue of over 600 configurations of oscillators and waveform generators, describing their relevant design details and salient performance features/limitations. The authors discuss a number of interesting, open research problems and include a comprehensive collection of over 1500 references on oscillators and non-sinusoidal waveform generators/relaxation oscillators. Offers readers a single-source reference to everything connected to sinusoidal oscillators and waveform generators, using classical as well as modern electronic circuit building blocks; Provides a state-of-the-art review of a large variety of sinusoidal oscillators and waveform generators; Includes a catalog of over 600 configurations of oscillato...
15. A Denoising Method for LiDAR Full-Waveform Data
Directory of Open Access Journals (Sweden)
Xudong Lai
2015-01-01
Full Text Available Decomposition of LiDAR full-waveform data can not only enhance the density and positioning accuracy of a point cloud, but also provide other useful parameters, such as pulse width, peak amplitude, and peak position which are important information for subsequent processing. Full-waveform data usually contain some random noises. Traditional filtering algorithms always cause distortion in the waveform. λ/μ filtering algorithm is based on Mean Shift method. It can smooth the signal iteratively and will not cause any distortion in the waveform. In this paper, an improved λ/μ filtering algorithm is proposed, and several experiments on both simulated waveform data and real waveform data are implemented to prove the effectiveness of the proposed algorithm.
16. Time-domain simulation and waveform reconstruction for shielding effectiveness of materials against electromagnetic pulse
International Nuclear Information System (INIS)
Hu, Xiao-feng; Chen, Xiang; Wei, Ming
2013-01-01
Shielding effectiveness (SE) of materials of current testing standards is often carried out by using continuous-wave measurement and amplitude-frequency characteristics curve is used to characterize the results. However, with in-depth study of high-power electromagnetic pulse (EMP) interference, it was discovered that only by frequency-domain SE of materials cannot be completely characterized by shielding performance of time-domain pulsed-field. And there is no uniform testing methods and standards of SE of materials against EMP. In this paper, the method of minimum phase transfer function is used to reconstruct shielded time-domain waveform based on the analysis of the waveform reconstruction method. Pulse of plane waves through an infinite planar material is simulated by using CST simulation software. The reconstructed waveform and simulation waveform is compared. The results show that the waveform reconstruction method based on the minimum phase can be well estimated EMP waveform through the infinite planar materials.
17. Waveform efficiency analysis of auditory nerve fiber stimulation for cochlear implants
International Nuclear Information System (INIS)
Navaii, Mehdi Lotfi; Sadhedi, Hamed; Jalali, Mohsen
2013-01-01
Evaluation of the electrical stimulation efficiency of various stimulating waveforms is an important issue for efficient neural stimulator design. Concerning the implantable micro devices design, it is also necessary to consider the feasibility of hardware implementation of the desired waveforms. In this paper, the charge, power and energy efficiency of four waveforms (i.e. square, rising ramp, triangular and rising ramp-decaying exponential) in various durations have been simulated and evaluated based on the computational model of the auditory nerve fibers. Moreover, for a fair comparison of their feasibility, a fully integrated current generator circuit has been developed so that the desired stimulating waveforms can be generated. The simulation results show that stimulation with the square waveforms is a proper choice in short and intermediate durations while the rising ramp-decaying exponential or triangular waveforms can be employed for long durations.
18. Inclined asymmetric librations in exterior resonances
Science.gov (United States)
Voyatzis, G.; Tsiganis, K.; Antoniadou, K. I.
2018-04-01
Librational motion in Celestial Mechanics is generally associated with the existence of stable resonant configurations and signified by the existence of stable periodic solutions and oscillation of critical (resonant) angles. When such an oscillation takes place around a value different than 0 or π , the libration is called asymmetric. In the context of the planar circular restricted three-body problem, asymmetric librations have been identified for the exterior mean motion resonances (MMRs) 1:2, 1:3, etc., as well as for co-orbital motion (1:1). In exterior MMRs the massless body is the outer one. In this paper, we study asymmetric librations in the three-dimensional space. We employ the computational approach of Markellos (Mon Not R Astron Soc 184:273-281, https://doi.org/10.1093/mnras/184.2.273, 1978) and compute families of asymmetric periodic orbits and their stability. Stable asymmetric periodic orbits are surrounded in phase space by domains of initial conditions which correspond to stable evolution and librating resonant angles. Our computations were focused on the spatial circular restricted three-body model of the Sun-Neptune-TNO system (TNO = trans-Neptunian object). We compare our results with numerical integrations of observed TNOs, which reveal that some of them perform 1:2 resonant, inclined asymmetric librations. For the stable 1:2 TNO librators, we find that their libration seems to be related to the vertically stable planar asymmetric orbits of our model, rather than the three-dimensional ones found in the present study.
19. Design and implement of system for browsing remote seismic waveform based on B/S schema
International Nuclear Information System (INIS)
Zheng Xuefeng; Shen Junyi; Wang Zhihai; Sun Peng; Jin Ping; Yan Feng
2006-01-01
Browsing remote seismic waveform based on B/S schema is of significance in modern seismic research and data service, and the technology should be improved urgently. This paper describes the basic plan, architecture and implement of system for browsing remote seismic waveform based on B/S schema. The problem to access, browse and edit the waveform data on serve from client only using browser has been solved. On this basis, the system has been established and been in use. (authors)
20. Computational Stimulation of the Basal Ganglia Neurons with Cost Effective Delayed Gaussian Waveforms.
Science.gov (United States)
2017-01-01
Deep brain stimulation (DBS) has compelling results in the desynchronization of the basal ganglia neuronal activities and thus, is used in treating the motor symptoms of Parkinson's disease (PD). Accurate definition of DBS waveform parameters could avert tissue or electrode damage, increase the neuronal activity and reduce energy cost which will prolong the battery life, hence avoiding device replacement surgeries. This study considers the use of a charge balanced Gaussian waveform pattern as a method to disrupt the firing patterns of neuronal cell activity. A computational model was created to simulate ganglia cells and their interactions with thalamic neurons. From the model, we investigated the effects of modified DBS pulse shapes and proposed a delay period between the cathodic and anodic parts of the charge balanced Gaussian waveform to desynchronize the firing patterns of the GPe and GPi cells. The results of the proposed Gaussian waveform with delay outperformed that of rectangular DBS waveforms used in in-vivo experiments. The Gaussian Delay Gaussian (GDG) waveforms achieved lower number of misses in eliciting action potential while having a lower amplitude and shorter length of delay compared to numerous different pulse shapes. The amount of energy consumed in the basal ganglia network due to GDG waveforms was dropped by 22% in comparison with charge balanced Gaussian waveforms without any delay between the cathodic and anodic parts and was also 60% lower than a rectangular charged balanced pulse with a delay between the cathodic and anodic parts of the waveform. Furthermore, by defining a Synchronization Level metric, we observed that the GDG waveform was able to reduce the synchronization of GPi neurons more effectively than any other waveform. The promising results of GDG waveforms in terms of eliciting action potential, desynchronization of the basal ganglia neurons and reduction of energy consumption can potentially enhance the performance of DBS
1. Full Waveform Inversion with Multisource Frequency Selection of Marine Streamer Data
KAUST Repository
Huang, Yunsong; Schuster, Gerard T.
2017-01-01
The theory and practice of multisource full waveform inversion of marine supergathers are described with a frequency-selection strategy. The key enabling property of frequency selection is that it eliminates the crosstalk among sources, thus overcoming the aperture mismatch of marine multisource inversion. Tests on multisource full waveform inversion of synthetic marine data and Gulf of Mexico data show speedups of 4× and 8×, respectively, compared to conventional full waveform inversion.
2. Computational Stimulation of the Basal Ganglia Neurons with Cost Effective Delayed Gaussian Waveforms
Directory of Open Access Journals (Sweden)
2017-08-01
Full Text Available Deep brain stimulation (DBS has compelling results in the desynchronization of the basal ganglia neuronal activities and thus, is used in treating the motor symptoms of Parkinson's disease (PD. Accurate definition of DBS waveform parameters could avert tissue or electrode damage, increase the neuronal activity and reduce energy cost which will prolong the battery life, hence avoiding device replacement surgeries. This study considers the use of a charge balanced Gaussian waveform pattern as a method to disrupt the firing patterns of neuronal cell activity. A computational model was created to simulate ganglia cells and their interactions with thalamic neurons. From the model, we investigated the effects of modified DBS pulse shapes and proposed a delay period between the cathodic and anodic parts of the charge balanced Gaussian waveform to desynchronize the firing patterns of the GPe and GPi cells. The results of the proposed Gaussian waveform with delay outperformed that of rectangular DBS waveforms used in in-vivo experiments. The Gaussian Delay Gaussian (GDG waveforms achieved lower number of misses in eliciting action potential while having a lower amplitude and shorter length of delay compared to numerous different pulse shapes. The amount of energy consumed in the basal ganglia network due to GDG waveforms was dropped by 22% in comparison with charge balanced Gaussian waveforms without any delay between the cathodic and anodic parts and was also 60% lower than a rectangular charged balanced pulse with a delay between the cathodic and anodic parts of the waveform. Furthermore, by defining a Synchronization Level metric, we observed that the GDG waveform was able to reduce the synchronization of GPi neurons more effectively than any other waveform. The promising results of GDG waveforms in terms of eliciting action potential, desynchronization of the basal ganglia neurons and reduction of energy consumption can potentially enhance the
3. Full Waveform Inversion with Multisource Frequency Selection of Marine Streamer Data
KAUST Repository
Huang, Yunsong
2017-10-27
The theory and practice of multisource full waveform inversion of marine supergathers are described with a frequency-selection strategy. The key enabling property of frequency selection is that it eliminates the crosstalk among sources, thus overcoming the aperture mismatch of marine multisource inversion. Tests on multisource full waveform inversion of synthetic marine data and Gulf of Mexico data show speedups of 4× and 8×, respectively, compared to conventional full waveform inversion.
4. Differential isospin-fractionation in dilute asymmetric nuclear matter
International Nuclear Information System (INIS)
Li Baoan; Chen Liewen; Ma Hongru; Xu Jun; Yong Gaochan
2007-01-01
The differential isospin-fractionation (IsoF) during the liquid-gas phase transition in dilute asymmetric nuclear matter is studied as a function of nucleon momentum. Within a self-consistent thermal model it is shown that the neutron/proton ratio of the gas phase becomes smaller than that of the liquid phase for energetic nucleons, although the gas phase is overall more neutron-rich. Clear indications of the differential IsoF consistent with the thermal model predictions are demonstrated within a transport model for heavy-ion reactions. Future comparisons with experimental data will allow us to extract critical information about the momentum dependence of the isovector strong interaction
5. Enhancement of nuclear reaction rates in asymmetric binary ionic mixtures
Energy Technology Data Exchange (ETDEWEB)
Clerouin, J.; Arnault, P.; Desbiens, N. [CEA, DAM, DIF, Arpajon (France); White, A.; Ticknor, C.; Kress, J.D.; Collins, L.A. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM (United States)
2017-11-15
Using orbital-free molecular dynamics simulations we study the structure and dynamics of increasingly asymmetric mixtures such as hydrogen-carbon, hydrogen-aluminium, hydrogen-copper, and hydrogen-silver. We show that, whereas the heavy component structure is close to an effective one-component plasma (OCP), the light component appears more structured than the corresponding OCP. This effect is related to the crossover towards a Lorentz-type diffusion triggered by strongly coupled, highly charged heavy ions, and witnessed by the change of temperature scaling laws of diffusion. This over-correlation translates into an enhancement of nuclear reaction rates much higher than its classical OCP counterpart. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
6. Colloidal Stability in Asymmetric Electrolytes: Modifications of the Schulze-Hardy Rule.
Science.gov (United States)
Trefalt, Gregor; Szilagyi, Istvan; Téllez, Gabriel; Borkovec, Michal
2017-02-21
The Schulze-Hardy rule suggests a strong dependence of the critical coagulation concentration (CCC) on the ionic valence. This rule is addressed theoretically and confronted with recent experimental results. The commonly presented derivation of this rule assumes symmetric electrolytes and highly charged particles. Both assumptions are incorrect. Symmetric electrolytes containing multivalent ions are hardly soluble, and experiments are normally carried out with the well-soluble salts of asymmetric electrolytes containing monovalent and multivalent ions. In this situation, however, the behavior is completely different whether the multivalent ions represent the counterions or co-ions. When these ions represent the counterions, meaning that the multivalent ions have the opposite sign than the charge of the particle, they adsorb strongly to the particles. Thereby, they progressively reduce the magnitude of the surface charge with increasing valence. In fact, this dependence of the charge density on the counterion valence is mainly responsible for the decrease of the CCC with the valence. In the co-ion case, where the multivalent ions have the same sign as the charge of the particle, the multivalent ions are repelled from the particles, and the surfaces remain highly charged. In this case, the inverse Schulze-Hardy rule normally applies, whereby the CCC varies inversely proportional to the co-ion valence.
7. Source-independent time-domain waveform inversion using convolved wavefields: Application to the encoded multisource waveform inversion
KAUST Repository
Choi, Yun Seok
2011-09-01
Full waveform inversion requires a good estimation of the source wavelet to improve our chances of a successful inversion. This is especially true for an encoded multisource time-domain implementation, which, conventionally, requires separate-source modeling, as well as the Fourier transform of wavefields. As an alternative, we have developed the source-independent time-domain waveform inversion using convolved wavefields. Specifically, the misfit function consists of the convolution of the observed wavefields with a reference trace from the modeled wavefield, plus the convolution of the modeled wavefields with a reference trace from the observed wavefield. In this case, the source wavelet of the observed and the modeled wavefields are equally convolved with both terms in the misfit function, and thus, the effects of the source wavelets are eliminated. Furthermore, because the modeled wavefields play a role of low-pass filtering, the observed wavefields in the misfit function, the frequency-selection strategy from low to high can be easily adopted just by setting the maximum frequency of the source wavelet of the modeled wavefields; and thus, no filtering is required. The gradient of the misfit function is computed by back-propagating the new residual seismograms and applying the imaging condition, similar to reverse-time migration. In the synthetic data evaluations, our waveform inversion yields inverted models that are close to the true model, but demonstrates, as predicted, some limitations when random noise is added to the synthetic data. We also realized that an average of traces is a better choice for the reference trace than using a single trace. © 2011 Society of Exploration Geophysicists.
8. A New Waveform Mosaic Algorithm in the Vectorization of Paper Seismograms
Directory of Open Access Journals (Sweden)
Maofa Wang
2014-11-01
Full Text Available History paper seismograms are very important information for earthquake monitoring and prediction, and the vectorization of paper seismograms is a very import problem to be resolved. In this paper, a new waveform mosaic algorithm in the vectorization of paper seismograms is presented. We also give out the technological process to waveform mosaic, and a waveform mosaic system used to vectorize analog seismic record has been accomplished independently. Using it, we can precisely and speedy accomplish waveform mosaic for vectorizing analog seismic records.
9. GO JUPITER PWS EDITED EDR 10KHZ WAVEFORM RECEIVER V1.0
Data.gov (United States)
National Aeronautics and Space Administration — This data set includes wideband waveform measurements from the Galileo plasma wave receiver obtained during Jupiter orbital operations. These data were obtained...
10. GO JUPITER PWS EDITED EDR 1KHZ WAVEFORM RECEIVER V1.0
Data.gov (United States)
National Aeronautics and Space Administration — This data set includes wideband waveform measurements from the Galileo plasma wave receiver obtained during Jupiter orbital operations. These data were obtained...
11. Development of plasma current waveform adjusting system ZLJ for tokamak device HL-1
International Nuclear Information System (INIS)
Wang Shangbing; Hu Haotian; Tang Fangqun; Zhou Yongzheng; Chu Xiuzhong; Cheng Jiashun; Gao Yunxia
1989-12-01
The control of some typical Tokamak discharge waveforms has been achieved by using plasma current waveform adjusting system ZLJ in the ohmic heating of HL-1. The discharge waveforms include a series of regular plasma current waveforms with various slow rising rate, such as 80 kA, 450 ms long flat-topping; 100 kA, 200 ms rising; 200 ms falt-topping and 180 kA, 400 ms slow rising etc. The design principle of the system and the initial experimental results are described
12. LPI Radar Waveform Recognition Based on Time-Frequency Distribution
Directory of Open Access Journals (Sweden)
Ming Zhang
2016-10-01
Full Text Available In this paper, an automatic radar waveform recognition system in a high noise environment is proposed. Signal waveform recognition techniques are widely applied in the field of cognitive radio, spectrum management and radar applications, etc. We devise a system to classify the modulating signals widely used in low probability of intercept (LPI radar detection systems. The radar signals are divided into eight types of classifications, including linear frequency modulation (LFM, BPSK (Barker code modulation, Costas codes and polyphase codes (comprising Frank, P1, P2, P3 and P4. The classifier is Elman neural network (ENN, and it is a supervised classification based on features extracted from the system. Through the techniques of image filtering, image opening operation, skeleton extraction, principal component analysis (PCA, image binarization algorithm and Pseudo–Zernike moments, etc., the features are extracted from the Choi–Williams time-frequency distribution (CWD image of the received data. In order to reduce the redundant features and simplify calculation, the features selection algorithm based on mutual information between classes and features vectors are applied. The superiority of the proposed classification system is demonstrated by the simulations and analysis. Simulation results show that the overall ratio of successful recognition (RSR is 94.7% at signal-to-noise ratio (SNR of −2 dB.
13. Frequency spectrum analysis of finger photoplethysmographic waveform variability during haemodialysis.
Science.gov (United States)
Javed, Faizan; Middleton, Paul M; Malouf, Philip; Chan, Gregory S H; Savkin, Andrey V; Lovell, Nigel H; Steel, Elizabeth; Mackie, James
2010-09-01
This study investigates the peripheral circulatory and autonomic response to volume withdrawal in haemodialysis based on spectral analysis of photoplethysmographic waveform variability (PPGV). Frequency spectrum analysis was performed on the baseline and pulse amplitude variabilities of the finger infrared photoplethysmographic (PPG) waveform and on heart rate variability extracted from the ECG signal collected from 18 kidney failure patients undergoing haemodialysis. Spectral powers were calculated from the low frequency (LF, 0.04-0.145 Hz) and high frequency (HF, 0.145-0.45 Hz) bands. In eight stable fluid overloaded patients (fluid removal of >2 L) not on alpha blockers, progressive reduction in relative blood volume during haemodialysis resulted in significant increase in LF and HF powers of PPG baseline and amplitude variability (P analysis of finger PPGV may provide valuable information on the autonomic vascular response to blood volume reduction in haemodialysis, and can be potentially utilized as a non-invasive tool for assessing peripheral circulatory control during routine dialysis procedure.
14. Elastic reflection based waveform inversion with a nonlinear approach
KAUST Repository
Guo, Qiang; Alkhalifah, Tariq Ali
2017-01-01
Full waveform inversion (FWI) is a highly nonlinear problem due to the complex reflectivity of the Earth, and this nonlinearity only increases under the more expensive elastic assumption. In elastic media, we need a good initial P-wave velocity and even a better initial S-wave velocity models with accurate representation of the low model wavenumbers for FWI to converge. However, inverting for the low wavenumber components of P- and S-wave velocities using reflection waveform inversion (RWI) with an objective to fit the reflection shape, rather than produce reflections, may mitigate the limitations of FWI. Because FWI, performing as a migration operator, is in preference of the high wavenumber updates along reflectors. We propose a nonlinear elastic RWI that inverts for both the low wavenumber and perturbation components of the P- and S-wave velocities. To generate the full elastic reflection wavefields, we derive an equivalent stress source made up by the inverted model perturbations and incident wavefields. We update both the perturbation and propagation parts of the velocity models in a nested fashion. Applications on synthetic isotropic models and field data show that our method can efficiently update the low and high wavenumber parts of the models.
15. Multiparameter Elastic Full Waveform Inversion with Facies-based Constraints
Science.gov (United States)
Zhang, Zhen-dong; Alkhalifah, Tariq; Naeini, Ehsan Zabihi; Sun, Bingbing
2018-03-01
Full waveform inversion (FWI) incorporates all the data characteristics to estimate the parameters described by the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion beyond improved acoustic imaging, like in reservoir delineation, faces inherent challenges related to the limited resolution and the potential trade-off between the elastic model parameters. Some anisotropic parameters are insufficiently updated because of their minor contributions to the surface collected data. Adding rock physics constraints to the inversion helps mitigate such limited sensitivity, but current approaches to add such constraints are based on including them as a priori knowledge mostly valid around the well or as a global constraint for the whole area. Since similar rock formations inside the Earth admit consistent elastic properties and relative values of elasticity and anisotropy parameters (this enables us to define them as a seismic facies), utilizing such localized facies information in FWI can improve the resolution of inverted parameters. We propose a novel approach to use facies-based constraints in both isotropic and anisotropic elastic FWI. We invert for such facies using Bayesian theory and update them at each iteration of the inversion using both the inverted models and a prior information. We take the uncertainties of the estimated parameters (approximated by radiation patterns) into consideration and improve the quality of estimated facies maps. Four numerical examples corresponding to different acquisition, physical assumptions and model circumstances are used to verify the effectiveness of the proposed method.
16. Elastic reflection based waveform inversion with a nonlinear approach
KAUST Repository
Guo, Qiang
2017-08-16
Full waveform inversion (FWI) is a highly nonlinear problem due to the complex reflectivity of the Earth, and this nonlinearity only increases under the more expensive elastic assumption. In elastic media, we need a good initial P-wave velocity and even a better initial S-wave velocity models with accurate representation of the low model wavenumbers for FWI to converge. However, inverting for the low wavenumber components of P- and S-wave velocities using reflection waveform inversion (RWI) with an objective to fit the reflection shape, rather than produce reflections, may mitigate the limitations of FWI. Because FWI, performing as a migration operator, is in preference of the high wavenumber updates along reflectors. We propose a nonlinear elastic RWI that inverts for both the low wavenumber and perturbation components of the P- and S-wave velocities. To generate the full elastic reflection wavefields, we derive an equivalent stress source made up by the inverted model perturbations and incident wavefields. We update both the perturbation and propagation parts of the velocity models in a nested fashion. Applications on synthetic isotropic models and field data show that our method can efficiently update the low and high wavenumber parts of the models.
17. Multiparameter Elastic Full Waveform Inversion With Facies Constraints
KAUST Repository
Zhang, Zhendong
2017-08-17
Full waveform inversion (FWI) aims fully benefit from all the data characteristics to estimate the parameters describing the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion as a tool beyond acoustic imaging applications, for example in reservoir analysis, faces inherent challenges related to the limited resolution and the potential trade-off between the elastic model parameters. Adding rock physics constraints does help to mitigate these issues, but current approaches to add such constraints are based on including them as a priori knowledge mostly valid around the well or as a boundary condition for the whole area. Since certain rock formations inside the Earth admit consistent elastic properties and relative values of elastic and anisotropic parameters (facies), utilizing such localized facies information in FWI can improve the resolution of inverted parameters. We propose a novel confidence map based approach to utilize the facies-based constraints in both isotropic and anisotropic elastic FWI. We invert for such a confidence map using Bayesian theory, in which the confidence map is updated at each iteration of the inversion using both the inverted models and a prior information. The numerical examples show that the proposed method can reduce the trade-offs and also can improve the resolution of the inverted elastic and anisotropic properties.
18. Full waveform inversion using envelope-based global correlation norm
Science.gov (United States)
Oh, Ju-Won; Alkhalifah, Tariq
2018-05-01
To increase the feasibility of full waveform inversion on real data, we suggest a new objective function, which is defined as the global correlation of the envelopes of modelled and observed data. The envelope-based global correlation norm has the advantage of the envelope inversion that generates artificial low-frequency information, which provides the possibility to recover long-wavelength structure in an early stage. In addition, the envelope-based global correlation norm maintains the advantage of the global correlation norm, which reduces the sensitivity of the misfit to amplitude errors so that the performance of inversion on real data can be enhanced when the exact source wavelet is not available and more complex physics are ignored. Through the synthetic example for 2-D SEG/EAGE overthrust model with inaccurate source wavelet, we compare the performance of four different approaches, which are the least-squares waveform inversion, least-squares envelope inversion, global correlation norm and envelope-based global correlation norm. Finally, we apply the envelope-based global correlation norm on the 3-D Ocean Bottom Cable (OBC) data from the North Sea. The envelope-based global correlation norm captures the strong reflections from the high-velocity caprock and generates artificial low-frequency reflection energy that helps us recover long-wavelength structure of the model domain in the early stages. From this long-wavelength model, the conventional global correlation norm is sequentially applied to invert for higher-resolution features of the model.
19. Expanding the frontiers of waveform imaging with Salvus
Science.gov (United States)
Afanasiev, M.; Boehm, C.; van Driel, M.; Krischer, L.; Fichtner, A.
2017-12-01
Mechanical waves are natural harbingers of information. From medical ultrasound to the normal modes of Sun, wave motion is often our best window into the character of some underlying continuum. For over a century, geophysicists have been using this window to peer deep into the Earth, developing techniques that have gone on to underlie much of world's energy economy. As computers and numerical techniques have become more powerful over the last several decades, seismologists have begun to scale back classical simplifying approximations of wave propagation physics. As a result, we are now approaching the ideal of full-waveform inversion'; maximizing the aperture of our window by taking the full complexity of wave motion into account.Salvus is a modern high-performance software suite which aims to bring recent developments in geophysical waveform inversion to new and exciting domains. In this short presentation we will look at the connections between these applications, with examples from non-destructive testing, medical imaging, seismic exploration, and (extra-) planetary seismology.
20. Individual Biometric Identification Using Multi-Cycle Electrocardiographic Waveform Patterns
Directory of Open Access Journals (Sweden)
Wonki Lee
2018-03-01
Full Text Available The electrocardiogram (ECG waveform conveys information regarding the electrical property of the heart. The patterns vary depending on the individual heart characteristics. ECG features can be potentially used for biometric recognition. This study presents a new method using the entire ECG waveform pattern for matching and demonstrates that the approach can potentially be employed for individual biometric identification. Multi-cycle ECG signals were assessed using an ECG measuring circuit, and three electrodes can be patched on the wrists or fingers for considering various measurements. For biometric identification, our-fold cross validation was used in the experiments for assessing how the results of a statistical analysis will generalize to an independent data set. Four different pattern matching algorithms, i.e., cosine similarity, cross correlation, city block distance, and Euclidean distances, were tested to compare the individual identification performances with a single channel of ECG signal (3-wire ECG. To evaluate the pattern matching for biometric identification, the ECG recordings for each subject were partitioned into training and test set. The suggested method obtained a maximum performance of 89.9% accuracy with two heartbeats of ECG signals measured on the wrist and 93.3% accuracy with three heartbeats for 55 subjects. The performance rate with ECG signals measured on the fingers improved up to 99.3% with two heartbeats and 100% with three heartbeats of signals for 20 subjects.
1. Observation of 45 GHz current waveforms using HTS sampler
International Nuclear Information System (INIS)
Maruyama, M.; Suzuki, H.; Hato, T.; Wakana, H.; Nakayama, K.; Ishimaru, Y.; Horibe, O.; Adachi, S.; Kamitani, A.; Suzuki, K.; Oshikubo, Y.; Tarutani, Y.; Tanabe, K.
2005-01-01
We succeeded in observing high-frequency current waveforms up to 45 GHz using a high-temperature superconducting (HTS) sampler. In this experiment, we used a sampler circuit with a superconducting pickup coil, which magnetically detects current signals flowing through a micro-strip line on a printed board placed outside the cryochamber. This type of measurement enables non-contact current-waveform observation that seems useful for analyses of EMI, defects in LSI, etc. Computer simulation reveals that one of our latest versions of HTS sampler circuits having Josephson transmission lines with optimized biases as buffers has a potential of sampling high-frequency signals with a bandwidth above 100 GHz. To realize the circuit parameters required in the simulations, we developed an HTS circuit fabrication process employing a lower ground plane structure with SrSnO 3 insulating layers. We consider that improvement of the circuit fabrication process and optimization of the pickup coil lead to much higher signal frequency observable by the sampler
2. Multiparameter Elastic Full Waveform Inversion with Facies-based Constraints
KAUST Repository
Zhang, Zhendong
2018-03-20
Full waveform inversion (FWI) incorporates all the data characteristics to estimate the parameters described by the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion beyond improved acoustic imaging, like in reservoir delineation, faces inherent challenges related to the limited resolution and the potential trade-off between the elastic model parameters. Some anisotropic parameters are insufficiently updated because of their minor contributions to the surface collected data. Adding rock physics constraints to the inversion helps mitigate such limited sensitivity, but current approaches to add such constraints are based on including them as a priori knowledge mostly valid around the well or as a global constraint for the whole area. Since similar rock formations inside the Earth admit consistent elastic properties and relative values of elasticity and anisotropy parameters (this enables us to define them as a seismic facies), utilizing such localized facies information in FWI can improve the resolution of inverted parameters. We propose a novel approach to use facies-based constraints in both isotropic and anisotropic elastic FWI. We invert for such facies using Bayesian theory and update them at each iteration of the inversion using both the inverted models and a prior information. We take the uncertainties of the estimated parameters (approximated by radiation patterns) into consideration and improve the quality of estimated facies maps. Four numerical examples corresponding to different acquisition, physical assumptions and model circumstances are used to verify the effectiveness of the proposed method.
3. Individual Biometric Identification Using Multi-Cycle Electrocardiographic Waveform Patterns.
Science.gov (United States)
Lee, Wonki; Kim, Seulgee; Kim, Daeeun
2018-03-28
The electrocardiogram (ECG) waveform conveys information regarding the electrical property of the heart. The patterns vary depending on the individual heart characteristics. ECG features can be potentially used for biometric recognition. This study presents a new method using the entire ECG waveform pattern for matching and demonstrates that the approach can potentially be employed for individual biometric identification. Multi-cycle ECG signals were assessed using an ECG measuring circuit, and three electrodes can be patched on the wrists or fingers for considering various measurements. For biometric identification, our-fold cross validation was used in the experiments for assessing how the results of a statistical analysis will generalize to an independent data set. Four different pattern matching algorithms, i.e., cosine similarity, cross correlation, city block distance, and Euclidean distances, were tested to compare the individual identification performances with a single channel of ECG signal (3-wire ECG). To evaluate the pattern matching for biometric identification, the ECG recordings for each subject were partitioned into training and test set. The suggested method obtained a maximum performance of 89.9% accuracy with two heartbeats of ECG signals measured on the wrist and 93.3% accuracy with three heartbeats for 55 subjects. The performance rate with ECG signals measured on the fingers improved up to 99.3% with two heartbeats and 100% with three heartbeats of signals for 20 subjects.
4. Continuous-waveform constant-current isolated physiological stimulator
Science.gov (United States)
Holcomb, Mark R.; Devine, Jack M.; Harder, Rene; Sidorov, Veniamin Y.
2012-04-01
We have developed an isolated continuous-waveform constant-current physiological stimulator that is powered and controlled by universal serial bus (USB) interface. The stimulator is composed of a custom printed circuit board (PCB), 16-MHz MSP430F2618 microcontroller with two integrated 12-bit digital to analog converters (DAC0, DAC1), high-speed H-Bridge, voltage-controlled current source (VCCS), isolated USB communication and power circuitry, two isolated transistor-transistor logic (TTL) inputs, and a serial 16 × 2 character liquid crystal display. The stimulators are designed to produce current stimuli in the range of ±15 mA indefinitely using a 20V source and to be used in ex vivo cardiac experiments, but they are suitable for use in a wide variety of research or student experiments that require precision control of continuous waveforms or synchronization with external events. The device was designed with customization in mind and has features that allow it to be integrated into current and future experimental setups. Dual TTL inputs allow replacement by two or more traditional stimulators in common experimental configurations. The MSP430 software is written in C++ and compiled with IAR Embedded Workbench 5.20.2. A control program written in C++ runs on a Windows personal computer and has a graphical user interface that allows the user to control all aspects of the device.
5. Acquisition of L2 Japanese Geminates: Training with Waveform Displays
Directory of Open Access Journals (Sweden)
Miki Motohashi-Saigo
2009-06-01
Full Text Available The value of waveform displays as visual feedback was explored in a training study involving perception and production of L2 Japanese by beginning-level L1 English learners. A pretest-posttest design compared auditory-visual (AV and auditory-only (A-only Web-based training. Stimuli were singleton and geminate /t,k,s/ followed by /a,u/ in two conditions (isolated words, carrier sentences. Fillers with long vowels were included. Participants completed a forced-choice identification task involving minimal triplets: singletons, geminates, long vowels (e.g., sasu, sassu, saasu. Results revealed a significant improvement in geminate identification following training, especially for AV; b significant effect of geminate (lowest scores for /s/; c no significant effect of condition; and d no significant improvement for the control group. Most errors were misperceptions of geminates as long vowels. Test of generalization revealed 5% decline in accuracy for AV and 14% for A-only. Geminate production improved significantly (especially for AV based on rater judgments; improvement was greatest for /k/ and smallest for /s/. Most production errors involved substitution of a singleton for a geminate. Post-study interviews produced positive comments on Web-based training. Waveforms increased awareness of durational differences. Results support the effectiveness of auditory-visual input in L2 perception training with transfer to novel stimuli and improved production.
6. Reversal modes in asymmetric Ni nanowires
Energy Technology Data Exchange (ETDEWEB)
Leighton, B.; Pereira, A. [Departamento de Fisica, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Escrig, J., E-mail: [email protected] [Departamento de Fisica, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile)
2012-11-15
We have investigated the evolution of the magnetization reversal mechanism in asymmetric Ni nanowires as a function of their geometry. Circular nanowires are found to reverse their magnetization by the propagation of a vortex domain wall, while in very asymmetric nanowires the reversal is driven by the propagation of a transverse domain wall. The effect of shape asymmetry of the wire on coercivity and remanence is also studied. Angular dependence of the remanence and coercivity is also addressed. Tailoring the magnetization reversal mechanism in asymmetric nanowires can be useful for magnetic logic and race-track memory, both of which are based on the displacement of magnetic domain walls. Finally, an alternative method to detect the presence of magnetic drops is proposed. - Highlights: Black-Right-Pointing-Pointer Asymmetry strongly modifies the magnetic behavior of a wire. Black-Right-Pointing-Pointer Very asymmetric nanowires reverse their magnetization by a transverse domain wall. Black-Right-Pointing-Pointer An alternative method to detect the presence of magnetic drops is proposed. Black-Right-Pointing-Pointer Tailoring the reversal mode in asymmetric nanowires can be useful for potential applications.
7. Changes of brachial arterial doppler waveform during immersion of the hand of young men in ice-cold water
International Nuclear Information System (INIS)
Kim, Young Goo
1994-01-01
To evaluate the changes of brachial arterial Doppler waveform during immersion of the hand of young men in ice-cold water. Doppler waveforms of brachial arteries in 11 young male patients were recorded before and during immersion of ipsilateral hand in ice-cold water(4-5 .deg. C). The procedure was repeated on separate days. Patterns of waveform during immersion were compared with the changes of pulsatility index. Four men showed high impedance waveforms, and 5 men showed low impedance waveforms during immersion both at the first and at the second study. Two men, however, showed high impedance waveforms at the first study and tow impedance waveforms at the second study. The pulsatility index rose and fell in high and low impedance waveforms, respectively. The changes of brachial arterial Doppler waveforms could be classified into high and low impedance patterns, probably reflecting the acute changes in downstream impedance during immersion of hand in ice-cold water
8. Diode-like properties of single- and multi-pore asymmetric track membranes
Science.gov (United States)
Zielinska, K.; Gapeeva, A. R.; Orelovich, O. L.; Apel, P. Yu.
2014-05-01
In this work, we investigated the ionic transport properties of asymmetric polyethylene terephthalate (PET) track membranes with the thickness of 5 μm. The samples containing single pores and arrays of many pores were fabricated by irradiation with accelerated ions and subsequent physicochemical treatment. The method of etching in the presence of a surface-active agent was used to prepare the pores with highly-tapered tip. The transport of monovalent inorganic ions through the nano-scale holes was studied in a conductivity cell. The effective pore radii, electrical conductance and rectification ratios of pores were measured. The geometric characteristics of nanopores were investigated using FESEM.
9. Heavy ion fusion accelerator research (HIFAR) year-end report, April 1, 1991--September 30, 1991
International Nuclear Information System (INIS)
1991-09-01
This report discusses the following topics: ion source for the final focusing scaling experiment; reference ILSE physics design; injector and ion source development; the injector matching section; beam merging in ILSE; short quadrupole magnet design; ILSE concept induction cell studies; fast split-harp emittance measurements using a multichannel waveform analyzer; and HIFAR staff roster
10. The selectivity of zirconium phosphate for caesium in electrochemical ion exchange
International Nuclear Information System (INIS)
Lain, M.J.
1988-11-01
The properties of amorphous zirconium phosphate are investigated as an inorganic ion exchanger for use in liquid waste treatment by electrochemical ion exchange. Experiments to determine and increase the selectivity for caesium exchange over sodium are discussed, including various pulsed waveforms and studies with rotating membranes. Automation of a sampling system with pH and atomic absorption measurements is described. (author)
11. Nonlinear waves in electron–positron–ion plasmas including charge ...
2017-01-04
Jan 4, 2017 ... The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E0 was reduced. The results are compared with satellite observations. Keywords. Nonlinear waves; low frequency; ion-acoustic waves. PACS Nos 52.35.Qz; 52.35.Fp; 52.35 ...
12. Renewable resource management under asymmetric information
DEFF Research Database (Denmark)
Jensen, Frank; Andersen, Peder; Nielsen, Max
2013-01-01
Asymmetric information between fishermen and the regulator is important within fisheries. The regulator may have less information about stock sizes, prices, costs, effort, productivity and catches than fishermen. With asymmetric information, a strong analytical tool is principal-agent analysis....... In this paper, we study asymmetric information about productivity within a principal-agent framework and a tax on fishing effort is considered. It is shown that a second best optimum can be achieved if the effort tax is designed such that low-productivity agents rent is exhausted, while high-productivity agents...... receive an information rent. The information rent is equivalent to the total incentive cost. The incentive costs arise as we want to reveal the agent's type....
13. Asymmetric synthesis II more methods and applications
CERN Document Server
Christmann, Mathias
2012-01-01
After the overwhelming success of 'Asymmetric Synthesis - The Essentials', narrating the colorful history of asymmetric synthesis, this is the second edition with latest subjects and authors. While the aim of the first edition was mainly to honor the achievements of the pioneers in asymmetric syntheses, the aim of this new edition was bringing the current developments, especially from younger colleagues, to the attention of students. The format of the book remained unchanged, i.e. short conceptual overviews by young leaders in their field including a short biography of the authors. The growing multidisciplinary research within chemistry is reflected in the selection of topics including metal catalysis, organocatalysis, physical organic chemistry, analytical chemistry, and its applications in total synthesis. The prospective reader of this book is a graduate or undergraduate student of advanced organic chemistry as well as the industrial chemist who wants to get a brief update on the current developments in th...
14. Hepatic vein Doppler waveform in patients with diffuse fatty infiltration of the liver
International Nuclear Information System (INIS)
Oguzkurt, Levent; Yildirim, Tulin; Torun, Dilek; Tercan, Fahri; Kizilkilic, Osman; Niron, E. Alp
2005-01-01
Objective: To determine the incidence of abnormal hepatic vein Doppler waveform in patients with diffuse fatty infiltration of the liver (FIL). Materials and methods: In this prospective study, 40 patients with diffuse FIL and 50 normal healthy adults who served as control group underwent hepatic vein (HV) Doppler ultrasonography. The patients with the diagnosis of FIL were 23 men (57.5%) and 17 women aged 30-62 years (mean age ± S.D., 42 ± 12 years). Subjects in the control group were 27 men (54%) and 23 women aged 34-65 years (mean age ± S.D., 45 ± 14 years). The diagnosis of FIL was confirmed with computed tomography density measurements. The waveforms of HV were classified into three groups: regular triphasic waveform, biphasic waveform without a reverse flow, and monophasic or flat waveform. Etiological factors for FIL were diabetes mellitus (DM), hyperlipidemia and obesity (body mass index > 25). Serum lipid profile was obtained from all the patients with FIL. Results: Seventeen of the 40 patients (43%) with FIL had an abnormal HV Doppler waveform, whereas only one of the 50 (2%) healthy subjects had an abnormal waveform. The difference in the distribution of normal Doppler waveform pattern between the patients and the control group was significant (P 0.05). There was not any correlation between the degree of fat infiltration and the hepatic vein waveform pattern (P = 0.60). Conclusion: Patients with fatty liver has a high rate of an abnormal hepatic vein Doppler waveform pattern which can be biphasic or monophasic. We could not find a relation between the etiological factors for FIL and the occurrence of an abnormal HV Doppler waveform
15. The effect of inlet waveforms on computational hemodynamics of patient-specific intracranial aneurysms.
Science.gov (United States)
Xiang, J; Siddiqui, A H; Meng, H
2014-12-18
Due to the lack of patient-specific inlet flow waveform measurements, most computational fluid dynamics (CFD) simulations of intracranial aneurysms usually employ waveforms that are not patient-specific as inlet boundary conditions for the computational model. The current study examined how this assumption affects the predicted hemodynamics in patient-specific aneurysm geometries. We examined wall shear stress (WSS) and oscillatory shear index (OSI), the two most widely studied hemodynamic quantities that have been shown to predict aneurysm rupture, as well as maximal WSS (MWSS), energy loss (EL) and pressure loss coefficient (PLc). Sixteen pulsatile CFD simulations were carried out on four typical saccular aneurysms using 4 different waveforms and an identical inflow rate as inlet boundary conditions. Our results demonstrated that under the same mean inflow rate, different waveforms produced almost identical WSS distributions and WSS magnitudes, similar OSI distributions but drastically different OSI magnitudes. The OSI magnitude is correlated with the pulsatility index of the waveform. Furthermore, there is a linear relationship between aneurysm-averaged OSI values calculated from one waveform and those calculated from another waveform. In addition, different waveforms produced similar MWSS, EL and PLc in each aneurysm. In conclusion, inlet waveform has minimal effects on WSS, OSI distribution, MWSS, EL and PLc and a strong effect on OSI magnitude, but aneurysm-averaged OSI from different waveforms has a strong linear correlation with each other across different aneurysms, indicating that for the same aneurysm cohort, different waveforms can consistently stratify (rank) OSI of aneurysms. Copyright © 2014 Elsevier Ltd. All rights reserved.
16. Asymmetric acoustic transmission in multiple frequency bands
Energy Technology Data Exchange (ETDEWEB)
Sun, Hong-xiang, E-mail: [email protected] [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Yuan, Shou-qi, E-mail: [email protected] [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Zhang, Shu-yi [Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)
2015-11-23
We report both experimentally and numerically that the multi-band device of the asymmetric acoustic transmission is realized by placing two periodic gratings with different periods on both sides of two brass plates immersed in water. The asymmetric acoustic transmission can exist in four frequency bands below 1500 kHz, which arises from the interaction between various diffractions from the two gratings and Lamb modes in the brass plates immersed in water. The results indicate that the device has the advantages of multiple band, broader bandwidth, and simpler structure. Our finding should have great potential applications in ultrasonic devices.
17. Asymmetric acoustic transmission in multiple frequency bands
International Nuclear Information System (INIS)
Sun, Hong-xiang; Yuan, Shou-qi; Zhang, Shu-yi
2015-01-01
We report both experimentally and numerically that the multi-band device of the asymmetric acoustic transmission is realized by placing two periodic gratings with different periods on both sides of two brass plates immersed in water. The asymmetric acoustic transmission can exist in four frequency bands below 1500 kHz, which arises from the interaction between various diffractions from the two gratings and Lamb modes in the brass plates immersed in water. The results indicate that the device has the advantages of multiple band, broader bandwidth, and simpler structure. Our finding should have great potential applications in ultrasonic devices
18. Depths of Intraplate Indian Ocean Earthquakes from Waveform Modeling
Science.gov (United States)
Baca, A. J.; Polet, J.
2014-12-01
The Indian Ocean is a region of complex tectonics and anomalous seismicity. The ocean floor in this region exhibits many bathymetric features, most notably the multiple inactive fracture zones within the Wharton Basin and the Ninetyeast Ridge. The 11 April 2012 MW 8.7 and 8.2 strike-slip events that took place in this area are unique because their rupture appears to have extended to a depth where brittle failure, and thus seismic activity, was considered to be impossible. We analyze multiple intraplate earthquakes that have occurred throughout the Indian Ocean to better constrain their focal depths in order to enhance our understanding of how deep intraplate events are occurring and more importantly determine if the ruptures are originating within a ductile regime. Selected events are located within the Indian Ocean away from major plate boundaries. A majority are within the deforming Indo-Australian tectonic plate. Events primarily display thrust mechanisms with some strike-slip or a combination of the two. All events are between MW5.5-6.5. Event selections were handled this way in order to facilitate the analysis of teleseismic waveforms using a point source approximation. From these criteria we gathered a suite of 15 intraplate events. Synthetic seismograms of direct P-waves and depth phases are computed using a 1-D propagator matrix approach and compared with global teleseismic waveform data to determine a best depth for each event. To generate our synthetic seismograms we utilized the CRUST1.0 software, a global crustal model that generates velocity values at the hypocenter of our events. Our waveform analysis results reveal that our depths diverge from the Global Centroid Moment Tensor (GCMT) depths, which underestimate our deep lithosphere events and overestimate our shallow depths by as much as 17 km. We determined a depth of 45km for our deepest event. We will show a comparison of our final earthquake depths with the lithospheric thickness based on
19. On the square arc voltage waveform model in magnetic discharge lamp studies
OpenAIRE
Molina, Julio; Sainz Sapera, Luis; Mesas García, Juan José
2011-01-01
The current number of magnetic and electronic ballast discharge lamps in power distribution systems is increasing because they perform better than incandescent lamps. This paper studies the magnetic discharge lamp modeling. In particular, the arc voltage waveform is analyzed and the limitations of the square waveform model are revealed from experimental measurements.
20. Auto-correlation based intelligent technique for complex waveform presentation and measurement
International Nuclear Information System (INIS)
Rana, K P S; Singh, R; Sayann, K S
2009-01-01
Waveform acquisition and presentation forms the heart of many measurement systems. Particularly, data acquisition and presentation of repeating complex signals like sine sweep and frequency-modulated signals introduces the challenge of waveform time period estimation and live waveform presentation. This paper presents an intelligent technique, for waveform period estimation of both the complex and simple waveforms, based on the normalized auto-correlation method. The proposed technique is demonstrated using LabVIEW based intensive simulations on several simple and complex waveforms. Implementation of the technique is successfully demonstrated using LabVIEW based virtual instrumentation. Sine sweep vibration waveforms are successfully presented and measured for electrodynamic shaker system generated vibrations. The proposed method is also suitable for digital storage oscilloscope (DSO) triggering, for complex signals acquisition and presentation. This intelligence can be embodied into the DSO, making it an intelligent measurement system, catering wide varieties of the waveforms. The proposed technique, simulation results, robustness study and implementation results are presented in this paper.
1. Screening for aortoiliac lesions by visual interpretation of the common femoral Doppler waveform
DEFF Research Database (Denmark)
Eiberg, J P; Jensen, F; Grønvall Rasmussen, J B
2001-01-01
to study the accuracy of simple visual interpretation of the common femoral artery Doppler waveform for screening the aorto-iliac segment for significant occlusive disease.......to study the accuracy of simple visual interpretation of the common femoral artery Doppler waveform for screening the aorto-iliac segment for significant occlusive disease....
2. Waveform measurement in mocrowave device characterization: impact on power amplifiers design
Directory of Open Access Journals (Sweden)
Roberto Quaglia
2016-07-01
Full Text Available This paper describes an example of a measurement setup enabling waveform measurements during the load-pull characterization of a microwave power device. The significance of this measurement feature is highlighted showing how waveform engineering can be exploited to design high efficiency microwave power amplifiers.
3. Use of the Kalman Filter for Aortic Pressure Waveform Noise Reduction.
Science.gov (United States)
Lam, Frank; Lu, Hsiang-Wei; Wu, Chung-Che; Aliyazicioglu, Zekeriya; Kang, James S
2017-01-01
Clinical applications that require extraction and interpretation of physiological signals or waveforms are susceptible to corruption by noise or artifacts. Real-time hemodynamic monitoring systems are important for clinicians to assess the hemodynamic stability of surgical or intensive care patients by interpreting hemodynamic parameters generated by an analysis of aortic blood pressure (ABP) waveform measurements. Since hemodynamic parameter estimation algorithms often detect events and features from measured ABP waveforms to generate hemodynamic parameters, noise and artifacts integrated into ABP waveforms can severely distort the interpretation of hemodynamic parameters by hemodynamic algorithms. In this article, we propose the use of the Kalman filter and the 4-element Windkessel model with static parameters, arterial compliance C , peripheral resistance R , aortic impedance r , and the inertia of blood L , to represent aortic circulation for generating accurate estimations of ABP waveforms through noise and artifact reduction. Results show the Kalman filter could very effectively eliminate noise and generate a good estimation from the noisy ABP waveform based on the past state history. The power spectrum of the measured ABP waveform and the synthesized ABP waveform shows two similar harmonic frequencies.
4. Influence of crystal orientation on magnetostriction waveform in grain orientated electrical steel
Energy Technology Data Exchange (ETDEWEB)
Kijima, Gou, E-mail: [email protected] [Steel Research Laboratory, JFE Steel Corporation, Kawasaki, 210-0855 (Japan); Yamaguchi, Hiroi; Senda, Kunihiro; Hayakawa, Yasuyuki [Steel Research Laboratory, JFE Steel Corporation, Kurashiki, 712-8511 (Japan)
2014-08-01
Aiming to gain insight into the mechanisms of grain-oriented electrical steel sheet magnetostriction waveforms, we investigated the influence of crystal orientations. An increase in the β angle results in an increase in the amplitude of magnetostriction waveform, but does not affect the waveform itself. By slanting the excitation direction to simulate the change of the α angle, change in the magnetostriction waveform and a constriction–extension transition point in the steel plate was observed. The amplitude, however, was not significantly affected. We explained the nature of constriction–extension transition point in the magnetostriction waveform by considering the magnetization rotation. We speculated that the change of waveform resulting from the increase in the coating tensile stress can be attributed to the phenomenon of the magnetization rotation becoming hard to be generated due to the increase of magnetic anisotropy toward [001] axis. - Highlights: • β angle is related with the amplitude of magnetostriction waveform. • α angle is related with the magnetostriction waveform itself. • The effect of α angle can be controlled by the effect of coating tensile stress.
5. Effects of waveform model systematics on the interpretation of GW150914
NARCIS (Netherlands)
2017-01-01
Parameter estimates of GW150914 were obtained using Bayesian inference, based on three semi-analytic waveform models for binary black hole coalescences. These waveform models differ from each other in their treatment of black hole spins, and all three models make some simplifying assumptions,
6. WaveformECG: A Platform for Visualizing, Annotating, and Analyzing ECG Data.
Science.gov (United States)
Winslow, Raimond L; Granite, Stephen; Jurado, Christian
2016-01-01
The electrocardiogram (ECG) is the most commonly collected data in cardiovascular research because of the ease with which it can be measured and because changes in ECG waveforms reflect underlying aspects of heart disease. Accessed through a browser, WaveformECG is an open source platform supporting interactive analysis, visualization, and annotation of ECGs.
7. Investigation of fatigue behavior of Pb(Zr0.45Ti0.55)O3 thin films under asymmetric polarization switching
Science.gov (United States)
Zhu, Hui; Chen, Yueyuan; Chu, Daping; Feng, Shiwei; Zhang, Yingqiao; Wang, Pengfei
2016-09-01
The fatigue of lead zirconate titanate (PZT) thin films was measured under repetitive switching using asymmetric square waves. The remnant polarization and coercive voltage were found to present regular changes in the initial 10 s, independent of the asymmetry or frequency of switching waves. We attributed the change to the relaxation of stress in the film and identified a coercive voltage V 0 of 0.6 V for the stress-free film. By comparing the coercive voltage and V 0, we found that a built-in electric field was induced by asymmetric switching, where the direction and magnitude were dependent on the degree of waveform asymmetry. Furthermore, the fatigue speed was suggested to be closely related to the generation rate of oxygen vacancies. It was confirmed by our result that a faster decay of remnant polarization can be obtained by applying square waves with a higher degree of asymmetry or symmetry of square waves with a lower frequency.
8. Early arrival waveform inversion of shallow seismic land data
KAUST Repository
Hanafy, Sherif M.
2013-09-22
We estimate the near-surface velocity distribution over Wadi Qudaid in Saudi Arabia by applying early arrival waveform inversion (EWI) to shallow seismic land data collected with source-receiver offsets no longer than 232 m. The main purpose is to characterize the shallow subsurface for its water storage and reuse potential. To enhance the accuracy of EWI, we extracted a natural source wavelet from the data, and also corrected for the attenuation effects with an estimated factor Q. Results suggest that, compared to traveltime tomography, EWI can generate a highly resolved velocity tomogram from shallow seismic data. The more accurate EWI tomogram can make an economically important difference in assessing the storage potential of this wadi; in this case we find an increase of 18% of storage potential in the EWI tomogram relative to the traveltime tomogram. This approach suggests that FWI might be a more accurate means for economically characterizing the water storage potential for wadis’ throughout the world.
9. Direct Synthesis of Microwave Waveforms for Quantum Computing
Science.gov (United States)
Raftery, James; Vrajitoarea, Andrei; Zhang, Gengyan; Leng, Zhaoqi; Srinivasan, Srikanth; Houck, Andrew
Current state of the art quantum computing experiments in the microwave regime use control pulses generated by modulating microwave tones with baseband signals generated by an arbitrary waveform generator (AWG). Recent advances in digital analog conversion technology have made it possible to directly synthesize arbitrary microwave pulses with sampling rates of 65 gigasamples per second (GSa/s) or higher. These new ultra-wide bandwidth AWG's could dramatically simplify the classical control chain for quantum computing experiments, presenting potential cost savings and reducing the number of components that need to be carefully calibrated. Here we use a Keysight M8195A AWG to study the viability of such a simplified scheme, demonstrating randomized benchmarking of a superconducting qubit with high fidelity.
10. Memory and convulsive stimulation: effects of stimulus waveform.
Science.gov (United States)
Spanis, C W; Squire, L R
1981-09-01
Electrical stimulation with brief pulses can produce a seizure requiring less energy than conventional sine-wave stimulation, and it has been suggested that brief-pulse stimulation might reduce the memory loss associated with electroconvulsive therapy (ECT). The authors evaluated the effects of electroconvulsive shock (ECS) on memory in mice by using various waveforms, current intensities, training-ECS intervals, pulse widths, and stimulus durations. When equated for ability to produce seizures, low-energy, brief-pulse stimulation caused as much amnesia as sine-wave stimulation and sometimes more. In the absence of comparisons of the amnesic effects of brief-pulse and sine-wave stimulation in humans, the use of brief pulses for administering ECT is unwarranted.
11. 3-D waveform tomography sensitivity kernels for anisotropic media
KAUST Repository
Djebbi, Ramzi
2014-01-01
The complications in anisotropic multi-parameter inversion lie in the trade-off between the different anisotropy parameters. We compute the tomographic waveform sensitivity kernels for a VTI acoustic medium perturbation as a tool to investigate this ambiguity between the different parameters. We use dynamic ray tracing to efficiently handle the expensive computational cost for 3-D anisotropic models. Ray tracing provides also the ray direction information necessary for conditioning the sensitivity kernels to handle anisotropy. The NMO velocity and η parameter kernels showed a maximum sensitivity for diving waves which results in a relevant choice of those parameters in wave equation tomography. The δ parameter kernel showed zero sensitivity; therefore it can serve as a secondary parameter to fit the amplitude in the acoustic anisotropic inversion. Considering the limited penetration depth of diving waves, migration velocity analysis based kernels are introduced to fix the depth ambiguity with reflections and compute sensitivity maps in the deeper parts of the model.
12. Conditioning the full waveform inversion gradient to welcome anisotropy
KAUST Repository
Alkhalifah, Tariq Ali
2014-01-01
Multi-parameter full waveform inversion (FWI) suffers from the complex nonlinearity in the objective function, compounded by the eventual tradeoff between the model parameters. A hierarchical approach based on frequency and arrival time data decimation to maneuver the complex nonlinearity associated with this problem usually falls short in anisotropic media. In place of data decimation, I use a model gradient filter approach to access the parts of the gradient more suitable to combat the potential nonlinearity and parameter trade off. The filter is based on representing the gradient in the time-lag normalized domain in which the small scattering angles of the gradient update is initially muted out. A model update hierarchical filtering strategy includes applying varying degree of filtering to the different parameter updates. A feature not easily accessible to simple data decimation. Using both FWI and reection based FWI (RFWI), two strategies to combat the tradeoff between anisotropic parameters are outlined.
13. Characterizing Geological Facies using Seismic Waveform Classification in Sarawak Basin
Science.gov (United States)
2017-10-01
Numerous effort have been made to build relationship between geology and geophysics using different techniques throughout the years. The integration of these two most important data in oil and gas industry can be used to reduce uncertainty in exploration and production especially for reservoir productivity enhancement and stratigraphic identification. This paper is focusing on seismic waveform classification to different classes using neural network and to link them according to the geological facies which are established using the knowledge on lithology and log motif of well data. Seismic inversion is used as the input for the neural network to act as the direct lithology indicator reducing dependency on well calibration. The interpretation of seismic facies classification map provides a better understanding towards the lithology distribution, depositional environment and help to identify significant reservoir rock
14. Automatic physiological waveform processing for FMRI noise correction and analysis.
Directory of Open Access Journals (Sweden)
Daniel J Kelley
2008-03-01
Full Text Available Functional MRI resting state and connectivity studies of brain focus on neural fluctuations at low frequencies which share power with physiological fluctuations originating from lung and heart. Due to the lack of automated software to process physiological signals collected at high magnetic fields, a gap exists in the processing pathway between the acquisition of physiological data and its use in fMRI software for both physiological noise correction and functional analyses of brain activation and connectivity. To fill this gap, we developed an open source, physiological signal processing program, called PhysioNoise, in the python language. We tested its automated processing algorithms and dynamic signal visualization on resting monkey cardiac and respiratory waveforms. PhysioNoise consistently identifies physiological fluctuations for fMRI noise correction and also generates covariates for subsequent analyses of brain activation and connectivity.
15. Real time monitoring of moment magnitude by waveform inversion
Science.gov (United States)
Lee, J.; Friederich, W.; Meier, T.
2012-01-01
An instantaneous measure of the moment magnitude (Mw) of an ongoing earthquake is estimated from the moment rate function (MRF) determined in real-time from available seismic data using waveform inversion. Integration of the MRF gives the moment function from which an instantaneous Mw is derived. By repeating the inversion procedure at regular intervals while seismic data are coming in we can monitor the evolution of seismic moment and Mw with time. The final size and duration of a strong earthquake can be obtained within 12 to 15 minutes after the origin time. We show examples of Mw monitoring for three large earthquakes at regional distances. The estimated Mw is only weakly sensitive to changes in the assumed source parameters. Depending on the availability of seismic stations close to the epicenter, a rapid estimation of the Mw as a prerequisite for the assessment of earthquake damage potential appears to be feasible.
16. Conditioning the full waveform inversion gradient to welcome anisotropy
KAUST Repository
Alkhalifah, Tariq Ali
2014-08-05
Multi-parameter full waveform inversion (FWI) suffers from the complex nonlinearity in the objective function, compounded by the eventual tradeoff between the model parameters. A hierarchical approach based on frequency and arrival time data decimation to maneuver the complex nonlinearity associated with this problem usually falls short in anisotropic media. In place of data decimation, I use a model gradient filter approach to access the parts of the gradient more suitable to combat the potential nonlinearity and parameter trade off. The filter is based on representing the gradient in the time-lag normalized domain in which the small scattering angles of the gradient update is initially muted out. A model update hierarchical filtering strategy includes applying varying degree of filtering to the different parameter updates. A feature not easily accessible to simple data decimation. Using both FWI and reection based FWI (RFWI), two strategies to combat the tradeoff between anisotropic parameters are outlined.
17. Full Waveform Inversion for Reservoir Characterization - A Synthetic Study
KAUST Repository
Zabihi Naeini, E.
2017-05-26
Most current reservoir-characterization workflows are based on classic amplitude-variation-with-offset (AVO) inversion techniques. Although these methods have generally served us well over the years, here we examine full-waveform inversion (FWI) as an alternative tool for higher-resolution reservoir characterization. An important step in developing reservoir-oriented FWI is the implementation of facies-based rock physics constraints adapted from the classic methods. We show that such constraints can be incorporated into FWI by adding appropriately designed regularization terms to the objective function. The advantages of the proposed algorithm are demonstrated on both isotropic and VTI (transversely isotropic with a vertical symmetry axis) models with pronounced lateral and vertical heterogeneity. The inversion results are explained using the theoretical radiation patterns produced by perturbations in the medium parameters.
18. Full-waveform inversion: From near surface to deep
KAUST Repository
Alkhalifah, Tariq Ali
2013-11-01
The ancient Persian Gulf port city of Muscat provided a spectacular setting for the SEG\\'s 2013 Workshop on Full-waveform Inversion (FWI). This active R&D topic attracted about 36 oral presentations and 20 or so posters, which added up to three intense days of ideas, images, and discussion. FWI has progressed from academic research topic to commercial workflow component in roughly 10 years, with many case studies documenting improved imaging and business value and others documenting a definite need for improved understanding of algorithms and applicability. Along with fundamental research issues of worldwide importance, the meeting provided an opportunity to showcase implications of the Middle East\\'s particular exploration challenges for the further development of FWI.
19. Optimal overlapping of waveform relaxation method for linear differential equations
International Nuclear Information System (INIS)
2000-01-01
Waveform relaxation (WR) method is extremely suitable for solving large systems of ordinary differential equations (ODEs) on parallel computers, but the convergence of the method is generally slow. In order to accelerate the convergence, the methods which decouple the system into many subsystems with overlaps some of the components between the adjacent subsystems have been proposed. The methods, in general, converge much faster than the ones without overlapping, but the computational cost per iteration becomes larger due to the increase of the dimension of each subsystem. In this research, the convergence of the WR method for solving constant coefficients linear ODEs is investigated and the strategy to determine the number of overlapped components which minimizes the cost of the parallel computations is proposed. Numerical experiments on an SR2201 parallel computer show that the estimated number of the overlapped components by the proposed strategy is reasonable. (author)
20. All-optical temporal integration of ultrafast pulse waveforms.
Science.gov (United States)
Park, Yongwoo; Ahn, Tae-Jung; Dai, Yitang; Yao, Jianping; Azaña, José
2008-10-27
An ultrafast all-optical temporal integrator is experimentally demonstrated. The demonstrated integrator is based on a very simple and practical solution only requiring the use of a widely available all-fiber passive component, namely a reflection uniform fiber Bragg grating (FBG). This design allows overcoming the severe speed (bandwidth) limitations of the previously demonstrated photonic integrator designs. We demonstrate temporal integration of a variety of ultrafast optical waveforms, including Gaussian, odd-symmetry Hermite Gaussian, and (odd-)symmetry double pulses, with temporal features as fast as ~6-ps, which is about one order of magnitude faster than in previous photonic integration demonstrations. The developed device is potentially interesting for a multitude of applications in all-optical computing and information processing, ultrahigh-speed optical communications, ultrafast pulse (de-)coding, shaping and metrology.
1. Reversible conduction block in peripheral nerve using electrical waveforms.
Science.gov (United States)
2018-01-01
Electrical nerve block uses electrical waveforms to block action potential propagation. Two key features that distinguish electrical nerve block from other nonelectrical means of nerve block: block occurs instantly, typically within 1 s; and block is fully and rapidly reversible (within seconds). Approaches for achieving electrical nerve block are reviewed, including kilohertz frequency alternating current and charge-balanced polarizing current. We conclude with a discussion of the future directions of electrical nerve block. Electrical nerve block is an emerging technique that has many significant advantages over other methods of nerve block. This field is still in its infancy, but a significant expansion in the clinical application of this technique is expected in the coming years.
2. ABOUT WAVEFORM OF BRAKING CYLINDER FILLING IN FREIGHT CARS
Directory of Open Access Journals (Sweden)
L. V. Ursuliak
2016-04-01
Full Text Available Purpose. As part of the scientific paper it is necessary to study the waveform impact of the braking cylinders filling on longitudinal train dynamics at different modes of braking. At this one should estimate the level of maximum longitudinal forces and braking distance size in freight cars of various lengths. Methodology. In this paper we attempt to approximate the actual diagram of braking cylinders filling with rational functions of varying degrees. In selection of coefficients in the required functions the highest values of the longitudinal forces and braking distances were used as controlled parameters. They were compared with similar values obtained as a result of experimental rides. The level of longitudinal forces and braking distances amount were evaluated by means of mathematical modeling of train longitudinal vibrations, caused by different braking modes. Findings. At mathematical modeling was assumed that the train consists of 60 uniform four-axle gondola cars, weight of 80 tons, equipped with air dispenser No. 483 included in the median operation, composite braking blocks, and one locomotive VL-8. Train before braking has been pre-stretched. Various types of pneumatic braking (emergency, full service and adjusting braking of the freight train on the horizontal section of the track were simulated. As the calculation results were obtained values of the longitudinal forces, braking distances amounts and reduction time in speed at various braking modes. Originality. Waveform impact of the braking cylinders filling on the longitudinal forces level and braking distances amount in freight trains were investigated. Also the longitudinal loading of freight trains at various pneumatic braking was investigated. Practical value. Obtained results can be used to assess the level of largest longitudinal forces and braking distances in the freight trains of different lengths by mathematical modeling of different braking modes.
3. Lossless compression of waveform data for efficient storage and transmission
International Nuclear Information System (INIS)
Stearns, S.D.; Tan, Li Zhe; Magotra, Neeraj
1993-01-01
Compression of waveform data is significant in many engineering and research areas since it can be used to alleviate data storage and transmission bandwidth. For example, seismic data are widely recorded and transmitted so that analysis can be performed on large amounts of data for numerous applications such as petroleum exploration, determination of the earth's core structure, seismic event detection and discrimination of underground nuclear explosions, etc. This paper describes a technique for lossless wave form data compression. The technique consists of two stages. The first stage is a modified form of linear prediction with discrete coefficients and the second stage is bi-level sequence coding. The linear predictor generates an error or residue sequence in a way such that exact reconstruction of the original data sequence can be accomplished with a simple algorithm. The residue sequence is essentially white Gaussian with seismic or other similar waveform data. Bi-level sequence coding, in which two sample sizes are chosen and the residue sequence is encoded into subsequences that alternate from one level to the other, further compresses the residue sequence. The principal feature of the two-stage data compression algorithm is that it is lossless, that is, it allows exact, bit-for-bit recovery of the original data sequence. The performance of the lossless compression algorithm at each stage is analyzed. The advantages of using bi-level sequence coding in the second stage are its simplicity of implementation, its effectiveness on data with large amplitude variations, and its near-optimal performance in encoding Gaussian sequences. Applications of the two-stage technique to typical seismic data indicates that an average number of compressed bits per sample close to the lower bound is achievable in practical situations
4. Ion-ion collisions
International Nuclear Information System (INIS)
Salzborn, Erhard; Melchert, Frank
2000-01-01
Collisions between ions belong to the elementary processes occurring in all types of plasmas. In this article we give a short overview about collisions involving one-electron systems. For collisions involving multiply-charged ions we limit the discussion to one specific quasi-one-electron system. (author)
5. Tailored ion energy distributions on plasma electrodes
International Nuclear Information System (INIS)
Economou, Demetre J.
2013-01-01
As microelectronic device features continue to shrink approaching atomic dimensions, control of the ion energy distribution on the substrate during plasma etching and deposition becomes increasingly critical. The ion energy should be high enough to drive ion-assisted etching, but not too high to cause substrate damage or loss of selectivity. In many cases, a nearly monoenergetic ion energy distribution (IED) is desired to achieve highly selective etching. In this work, the author briefly reviews: (1) the fundamentals of development of the ion energy distribution in the sheath and (2) methods to control the IED on plasma electrodes. Such methods include the application of “tailored” voltage waveforms on an electrode in continuous wave plasmas, or the application of synchronous bias on a “boundary electrode” during a specified time window in the afterglow of pulsed plasmas
6. Standards vs. labels with imperfect competition and asymmetric information
DEFF Research Database (Denmark)
Baltzer, Kenneth Thomas
2012-01-01
I demonstrate that providing information about product quality is not necessarily the best way to address asymmetric information problems when markets are imperfectly competitive. In a vertical differentiation model I show that a Minimum Quality Standard, which retains asymmetric information...
7. Standards vs. labels with imperfect competition and asymmetric information
DEFF Research Database (Denmark)
Baltzer, Kenneth Thomas
I demonstrate that providing information about product quality is not necessarily the best way to address asymmetric information problems when markets are imperfectly competitive. In a vertical dierentiation model I show that a Minimum Quality Standard, which retains asymmetric information...
8. Ultimate waveform reproducibility of extreme-ultraviolet pulses by high-harmonic generation in quartz
Science.gov (United States)
Garg, M.; Kim, H. Y.; Goulielmakis, E.
2018-05-01
Optical waveforms of light reproducible with subcycle precision underlie applications of lasers in ultrafast spectroscopies, quantum control of matter and light-based signal processing. Nonlinear upconversion of optical pulses via high-harmonic generation in gas media extends these capabilities to the extreme ultraviolet (EUV). However, the waveform reproducibility of the generated EUV pulses in gases is inherently sensitive to intensity and phase fluctuations of the driving field. We used photoelectron interferometry to study the effects of intensity and carrier-envelope phase of an intense single-cycle optical pulse on the field waveform of EUV pulses generated in quartz nanofilms, and contrasted the results with those obtained in gas argon. The EUV waveforms generated in quartz were found to be virtually immune to the intensity and phase of the driving field, implying a non-recollisional character of the underlying emission mechanism. Waveform-sensitive photonic applications and precision measurements of fundamental processes in optics will benefit from these findings.
9. Variance stabilization for computing and comparing grand mean waveforms in MEG and EEG.
Science.gov (United States)
Matysiak, Artur; Kordecki, Wojciech; Sielużycki, Cezary; Zacharias, Norman; Heil, Peter; König, Reinhard
2013-07-01
Grand means of time-varying signals (waveforms) across subjects in magnetoencephalography (MEG) and electroencephalography (EEG) are commonly computed as arithmetic averages and compared between conditions, for example, by subtraction. However, the prerequisite for these operations, homogeneity of the variance of the waveforms in time, and for most common parametric statistical tests also between conditions, is rarely met. We suggest that the heteroscedasticity observed instead results because waveforms may differ by factors and additive terms and follow a mixed model. We propose to apply the asinh-transformation to stabilize the variance in such cases. We demonstrate the homogeneous variance and the normal distributions of data achieved by this transformation using simulated waveforms, and we apply it to real MEG data and show its benefits. The asinh-transformation is thus an essential and useful processing step prior to computing and comparing grand mean waveforms in MEG and EEG. Copyright © 2013 Society for Psychophysiological Research.
10. Vortex Dynamics of Asymmetric Heave Plates
Science.gov (United States)
Rusch, Curtis; Maurer, Benjamin; Polagye, Brian
2017-11-01
Heave plates can be used to provide reaction forces for wave energy converters, which harness the power in ocean surface waves to produce electricity. Heave plate inertia includes both the static mass of the heave plate, as well as the added mass'' of surrounding water accelerated with the object. Heave plate geometries may be symmetric or asymmetric, with interest in asymmetric designs driven by the resulting hydrodynamic asymmetry. Limited flow visualization has been previously conducted on symmetric heave plates, but flow visualization of asymmetric designs is needed to understand the origin of observed hydrodynamic asymmetries and their dependence on the Keulegan-Carpenter number. For example, it is hypothesized that the time-varying added mass of asymmetric heave plates is caused by vortex shedding, which is related to oscillation amplitude. Here, using direct flow visualization, we explore the relationship between vortex dynamics and time-varying added mass and drag. These results suggest potential pathways for more advanced heave plate designs that can exploit vortex formation and shedding to achieve more favorable hydrodynamic properties for wave energy converters.
11. Asymmetric hindwing foldings in rove beetles.
Science.gov (United States)
Saito, Kazuya; Yamamoto, Shuhei; Maruyama, Munetoshi; Okabe, Yoji
2014-11-18
Foldable wings of insects are the ultimate deployable structures and have attracted the interest of aerospace engineering scientists as well as entomologists. Rove beetles are known to fold their wings in the most sophisticated ways that have right-left asymmetric patterns. However, the specific folding process and the reason for this asymmetry remain unclear. This study reveals how these asymmetric patterns emerge as a result of the folding process of rove beetles. A high-speed camera was used to reveal the details of the wing-folding movement. The results show that these characteristic asymmetrical patterns emerge as a result of simultaneous folding of overlapped wings. The revealed folding mechanisms can achieve not only highly compact wing storage but also immediate deployment. In addition, the right and left crease patterns are interchangeable, and thus each wing internalizes two crease patterns and can be folded in two different ways. This two-way folding gives freedom of choice for the folding direction to a rove beetle. The use of asymmetric patterns and the capability of two-way folding are unique features not found in artificial structures. These features have great potential to extend the design possibilities for all deployable structures, from space structures to articles of daily use.
12. Mixed gas plasticization phenomena in asymmetric membranes
NARCIS (Netherlands)
Visser, Tymen
2006-01-01
This thesis describes the thorough investigation of mixed gas transport behavior of asymmetric membranes in the separation of feed streams containing plasticizing gases in order to gain more insights into the complicated behavior of plasticization. To successfully employ gas separation membranes in
13. Asymmetric conditional volatility in international stock markets
Science.gov (United States)
Ferreira, Nuno B.; Menezes, Rui; Mendes, Diana A.
2007-08-01
Recent studies show that a negative shock in stock prices will generate more volatility than a positive shock of similar magnitude. The aim of this paper is to appraise the hypothesis under which the conditional mean and the conditional variance of stock returns are asymmetric functions of past information. We compare the results for the Portuguese Stock Market Index PSI 20 with six other Stock Market Indices, namely the SP 500, FTSE 100, DAX 30, CAC 40, ASE 20, and IBEX 35. In order to assess asymmetric volatility we use autoregressive conditional heteroskedasticity specifications known as TARCH and EGARCH. We also test for asymmetry after controlling for the effect of macroeconomic factors on stock market returns using TAR and M-TAR specifications within a VAR framework. Our results show that the conditional variance is an asymmetric function of past innovations raising proportionately more during market declines, a phenomenon known as the leverage effect. However, when we control for the effect of changes in macroeconomic variables, we find no significant evidence of asymmetric behaviour of the stock market returns. There are some signs that the Portuguese Stock Market tends to show somewhat less market efficiency than other markets since the effect of the shocks appear to take a longer time to dissipate.
14. MHD stability of vertically asymmetric tokamak equilibria
International Nuclear Information System (INIS)
Dalhed, H.E.; Grimm, R.C.; Johnson, J.L.
1981-03-01
The ideal MHD stability properties of a special class of vertically asymmetric tokamak equilibria are examined. The calculations confirm that no major new physical effects are introduced and the modifications can be understood by conventional arguments. The results indicate that significant departures from up-down symmetry can be tolerated before the reduction in β becomes important for reactor operation
15. Catalytic asymmetric synthesis of the alkaloid (+)-myrtine
NARCIS (Netherlands)
Pizzuti, Maria Gabriefla; Minnaard, Adriaan J.; Feringa, Ben L.
2008-01-01
A new protocol for the asymmetric synthesis of trans-2,6-disubstituted-4-piperidones has been developed using a catalytic enantioselective conjugate addition reaction in combination with a diastereoselective lithiation-substitution sequence; an efficient synthesis of (+)-myrtine has been achieved
16. Asymmetric Aminalization via Cation-Binding Catalysis
DEFF Research Database (Denmark)
Park, Sang Yeon; Liu, Yidong; Oh, Joong Suk
2018-01-01
Asymmetric cation-binding catalysis, in principle, can generate "chiral" anionic nucleophiles, where the counter cations are coordinated within chiral environments. Nitrogen-nucleophiles are intrinsically basic, therefore, its use as nucleophiles is often challenging and limiting the scope of the...
17. Volume inequalities for asymmetric Wulff shapes
OpenAIRE
Schuster, Franz E.; Weberndorfer, Manuel
2012-01-01
Sharp reverse affine isoperimetric inequalities for asymmetric Wulff shapes and their polars are established, along with the characterization of all extremals. These new inequalities have as special cases previously obtained simplex inequalities by Ball, Barthe and Lutwak, Yang, and Zhang. In particular, they provide the solution to a problem by Zhang.
18. Quantum optics of lossy asymmetric beam splitters
NARCIS (Netherlands)
Uppu, Ravitej; Wolterink, Tom; Tentrup, Tristan Bernhard Horst; Pinkse, Pepijn Willemszoon Harry
2016-01-01
We theoretically investigate quantum interference of two single photons at a lossy asymmetric beam splitter, the most general passive 2×2 optical circuit. The losses in the circuit result in a non-unitary scattering matrix with a non-trivial set of constraints on the elements of the scattering
19. Motion in an Asymmetric Double Well
OpenAIRE
Brizard, Alain J.; Westland, Melissa C.
2016-01-01
The problem of the motion of a particle in an asymmetric double well is solved explicitly in terms of the Weierstrass and Jacobi elliptic functions. While the solution of the orbital motion is expressed simply in terms of the Weierstrass elliptic function, the period of oscillation is more directly expressed in terms of periods of the Jacobi elliptic functions.
20. Asymmetric output profile of Xe Laser
NARCIS (Netherlands)
Blok, F.J.; Rubin, P.L.; Verschuur, Jeroen W.J.; Witteman, W.J.
2001-01-01
A new set of asymmetric modes was recently revealed in a Xe slab laser with pronounced lens effects originating from gas heating in the discharge. The appearance of these modes is a threshold effect. Their domain of existence in the Xe laser is discussed. It is shown that mode competition can result
1. Computing modal dispersion characteristics of radially Asymmetric ...
African Journals Online (AJOL)
We developed a matrix theory that applies to with non-circular/circular but concentric layers fibers. And we compute the dispersion characteristics of radially unconventional fiber, known as Asymmetric Bragg fiber. An attempt has been made to determine how the modal characteristics change as circular Bragg fiber is ...
2. Seasonally asymmetric enhancement of northern vegetation productivity
Science.gov (United States)
Park, T.; Myneni, R.
2017-12-01
Multiple evidences of widespread greening and increasing terrestrial carbon uptake have been documented. In particular, enhanced gross productivity of northern vegetation has been a critical role leading to observed carbon uptake trend. However, seasonal photosynthetic activity and its contribution to observed annual carbon uptake trend and interannual variability are not well understood. Here, we introduce a multiple-source of datasets including ground, atmospheric and satellite observations, and multiple process-based global vegetation models to understand how seasonal variation of land surface vegetation controls a large-scale carbon exchange. Our analysis clearly shows a seasonally asymmetric enhancement of northern vegetation productivity in growing season during last decades. Particularly, increasing gross productivity in late spring and early summer is obvious and dominant driver explaining observed trend and variability. We observe more asymmetric productivity enhancement in warmer region and this spatially varying asymmetricity in northern vegetation are likely explained by canopy development rate, thermal and light availability. These results imply that continued warming may facilitate amplifying asymmetric vegetation activity and cause these trends to become more pervasive, in turn warming induced regime shift in northern land.
3. Charge Asymmetric Cosmic Rays as a probe of Flavor Violating Asymmetric Dark Matter
DEFF Research Database (Denmark)
Masina, Isabella; Sannino, Francesco
2011-01-01
The recently introduced cosmic sum rules combine the data from PAMELA and Fermi-LAT cosmic ray experiments in a way that permits to neatly investigate whether the experimentally observed lepton excesses violate charge symmetry. One can in a simple way determine universal properties of the unknown...... component of the cosmic rays. Here we attribute a potential charge asymmetry to the dark sector. In particular we provide models of asymmetric dark matter able to produce charge asymmetric cosmic rays. We consider spin zero, spin one and spin one-half decaying dark matter candidates. We show that lepton...... flavor violation and asymmetric dark matter are both required to have a charge asymmetry in the cosmic ray lepton excesses. Therefore, an experimental evidence of charge asymmetry in the cosmic ray lepton excesses implies that dark matter is asymmetric....
4. Doppler Aliasing Reduction in Wide-Angle Synthetic Aperture Radar Using Phase Modulated Random Stepped-Frequency Waveforms
National Research Council Canada - National Science Library
Hyatt, Andrew W
2006-01-01
...) waveforms in a Wide-Angle Synthetic Aperture Radar (WA-SAR) scenario. RSF waveforms have been demonstrated to have desirable properties which allow for cancelling of Doppler aliased scatterers in WA-SAR images...
5. Nonlinear waves in electron-positron-ion plasmas including charge separation
Science.gov (United States)
Mugemana, A.; Moolla, S.; Lazarus, I. J.
2017-02-01
Nonlinear low-frequency electrostatic waves in a magnetized, three-component plasma consisting of hot electrons, hot positrons and warm ions have been investigated. The electrons and positrons are assumed to have Boltzmann density distributions while the motion of the ions are governed by fluid equations. The system is closed with the Poisson equation. This set of equations is numerically solved for the electric field. The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are sinusoidal, sawtooth and spiky. The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E 0 was reduced. The results are compared with satellite observations.
6. Ion implantation
International Nuclear Information System (INIS)
Dearnaley, Geoffrey
1975-01-01
First, ion implantation in semiconductors is discussed: ion penetration, annealing of damage, gettering, ion implanted semiconductor devices, equipement requirements for ion implantation. The importance of channeling for ion implantation is studied. Then, some applications of ion implantation in metals are presented: study of the corrosion of metals and alloys; influence or ion implantation on the surface-friction and wear properties of metals; hyperfine interactions in implanted metals
7. What is the best site for measuring the effect of ventilation on the pulse oximeter waveform?
Science.gov (United States)
Shelley, Kirk H; Jablonka, Denis H; Awad, Aymen A; Stout, Robert G; Rezkanna, Hoda; Silverman, David G
2006-08-01
The cardiac pulse is the predominant feature of the pulse oximeter (plethysmographic) waveform. Less obvious is the effect of ventilation on the waveform. There have been efforts to measure the effect of ventilation on the waveform to determine respiratory rate, tidal volume, and blood volume. We measured the relative strength of the effect of ventilation on the reflective plethysmographic waveform at three different sites: the finger, ear, and forehead. The plethysmographic waveforms from 18 patients undergoing positive pressure ventilation during surgery and 10 patients spontaneously breathing during renal dialysis were collected. The respiratory signal was isolated from the waveform using spectral analysis. It was found that the respiratory signal in the pulse oximeter waveform was more than 10 times stronger in the region of the head when compared with the finger. This was true with both controlled positive pressure ventilation and spontaneous breathing. A significant correlation was demonstrated between the estimated blood loss from surgical procedures and the impact of ventilation on ear plethysmographic data (r(s) = 0.624, P = 0.006).
8. Asymmetric Electrodes Constructed with PAN-Based Activated Carbon Fiber in Capacitive Deionization
Directory of Open Access Journals (Sweden)
Mingzhe Li
2014-01-01
Full Text Available Capacitive deionization (CDI method has drawn much attention for its low energy consumption, low pollution, and convenient manipulation. Activated carbon fibers (ACFs possess high adsorption ability and can be used as CDI electrode material. Herein, two kinds of PAN-based ACFs with different specific surface area (SSA were used for the CDI electrodes. The CDI performance was investigated; especially asymmetric electrodes’ effect was evaluated. The results demonstrated that PAN-based ACFs showed a high electrosorption rate (complete electrosorption in less than half an hour and moderate electrosorption capacity (up to 0.2 mmol/g. CDI experiments with asymmetric electrodes displayed a variation in electrosorption capacity between forward voltage and reverse voltage. It can be attributed to the electrical double layer (EDL overlap effect and inner pore potential; thus the ions with smaller hydrated ionic radius can be adsorbed more easily.
9. Apparent molal volumes of symmetrical and asymmetrical isomers of tetrabutylammonium bromide in water at several temperatures
International Nuclear Information System (INIS)
Moreno, Nicolás; Malagón, Andrés; Buchner, Richard; Vargas, Edgar F.
2014-01-01
Highlights: • Apparent molal volumes of five isomers of Bu 4 NBr in water have been measured. • The structural effect of branched and linear chains is discussed. • The structural contributions to the ionic volume were calculated. -- Abstract: Apparent molal volumes of a series of differently substituted quaternary ammonium bromides, namely tetra-iso-butyl-, tetra-sec-butyl-, tetra-n-butyl-, di-n-butyl-di-sec-butyl- and di-n-butyl-di-iso-butylammonium bromide have been determined as a function of molal concentration at (298.15, 303.15 and 308.15) K. Partial molar volumes at infinite dilution and ionic molar volumes of these quaternary ammonium cations were determined. Structural volume contributions to the ionic molar volume were also calculated. The symmetric and asymmetric quaternary ammonium cations are “structure making” ions. The contribution of the branched butyl chains predominates over the linear butyl chains in the asymmetric cations
10. EPG waveform library for Graphocephala atropunctata (Hemiptera: Cicadellidae): Effect of adhesive, input resistor, and voltage levels on waveform appearance and stylet probing behaviors.
Science.gov (United States)
Cervantes, Felix A; Backus, Elaine A
2018-05-31
Blue-green sharpshooter, Graphocephala atropunctata, is a native California vector of Xylella fastidiosa (Xf), a foregut-borne bacterium that is the causal agent of Pierce's disease in grapevines. A 3rd-generation, AC-DC electropenetrograph (EPG monitor) was used to record stylet probing and ingestion behaviors of adult G. atropunctata on healthy grapevines. This study presents for the first time a complete, updated waveform library for this species, as well as effects of different electropenetrograph settings and adhesives on waveform appearances. Both AC and DC applied signals were used with input resistor (Ri) levels (amplifier sensitivities) of 10 6 , 10 7 , 10 8 and 10 9 Ohms, as well as two type of adhesives, conducting silver paint and handmade silver glue. Waveform description, characterization of electrical origins (R versus emf components), and proposed biological meanings of waveforms are reported, as well as qualitative differences in waveform appearances observed with different electropenetrograph settings and adhesives. In addition, a quantitative study with AC signal, using two applied voltage levels (50 and 200 mV) and two Ri levels (10 7 and 10 9 Ohms) was performed. Intermediate Ri levels 10 7 and 10 8 Ohms provided EPG waveforms with the greatest amount of information, because both levels captured similar proportions of R and emf components, as supported by appearance, clarity, and definition of waveforms. Similarly, use of a gold wire loop plus handmade silver glue provided more definition of waveforms than a gold wire loop plus commercial conducting silver paint. Qualitative/observational evidence suggested that AC applied signal caused fewer aberrant behaviors/waveforms than DC applied signal. In the quantitative study, behavioral components of the sharpshooter X wave were the most affected by changes in Ri and voltage level. Because the X wave probably represents X. fastidiosa inoculation behavior, future studies of X. fastidiosa
11. Reference respiratory waveforms by minimum jerk model analysis
Energy Technology Data Exchange (ETDEWEB)
Anetai, Yusuke, E-mail: [email protected]; Sumida, Iori; Takahashi, Yutaka; Yagi, Masashi; Mizuno, Hirokazu; Ogawa, Kazuhiko [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Yamadaoka 2-2, Suita-shi, Osaka 565-0871 (Japan); Ota, Seiichi [Department of Medical Technology, Osaka University Hospital, Yamadaoka 2-15, Suita-shi, Osaka 565-0871 (Japan)
2015-09-15
Purpose: CyberKnife{sup ®} robotic surgery system has the ability to deliver radiation to a tumor subject to respiratory movements using Synchrony{sup ®} mode with less than 2 mm tracking accuracy. However, rapid and rough motion tracking causes mechanical tracking errors and puts mechanical stress on the robotic joint, leading to unexpected radiation delivery errors. During clinical treatment, patient respiratory motions are much more complicated, suggesting the need for patient-specific modeling of respiratory motion. The purpose of this study was to propose a novel method that provides a reference respiratory wave to enable smooth tracking for each patient. Methods: The minimum jerk model, which mathematically derives smoothness by means of jerk, or the third derivative of position and the derivative of acceleration with respect to time that is proportional to the time rate of force changed was introduced to model a patient-specific respiratory motion wave to provide smooth motion tracking using CyberKnife{sup ®}. To verify that patient-specific minimum jerk respiratory waves were being tracked smoothly by Synchrony{sup ®} mode, a tracking laser projection from CyberKnife{sup ®} was optically analyzed every 0.1 s using a webcam and a calibrated grid on a motion phantom whose motion was in accordance with three pattern waves (cosine, typical free-breathing, and minimum jerk theoretical wave models) for the clinically relevant superior–inferior directions from six volunteers assessed on the same node of the same isocentric plan. Results: Tracking discrepancy from the center of the grid to the beam projection was evaluated. The minimum jerk theoretical wave reduced the maximum-peak amplitude of radial tracking discrepancy compared with that of the waveforms modeled by cosine and typical free-breathing model by 22% and 35%, respectively, and provided smooth tracking for radial direction. Motion tracking constancy as indicated by radial tracking discrepancy
12. Full Waveform Inversion Using Oriented Time Migration Method
KAUST Repository
Zhang, Zhendong
2016-04-12
Full waveform inversion (FWI) for reflection events is limited by its linearized update requirements given by a process equivalent to migration. Unless the background velocity model is reasonably accurate the resulting gradient can have an inaccurate update direction leading the inversion to converge into what we refer to as local minima of the objective function. In this thesis, I first look into the subject of full model wavenumber to analysis the root of local minima and suggest the possible ways to avoid this problem. And then I analysis the possibility of recovering the corresponding wavenumber components through the existing inversion and migration algorithms. Migration can be taken as a generalized inversion method which mainly retrieves the high wavenumber part of the model. Conventional impedance inversion method gives a mapping relationship between the migration image (high wavenumber) and model parameters (full wavenumber) and thus provides a possible cascade inversion strategy to retrieve the full wavenumber components from seismic data. In the proposed approach, consider a mild lateral variation in the model, I find an analytical Frechet derivation corresponding to the new objective function. In the proposed approach, the gradient is given by the oriented time-domain imaging method. This is independent of the background velocity. Specifically, I apply the oriented time-domain imaging (which depends on the reflection slope instead of a background velocity) on the data residual to obtain the geometrical features of the velocity perturbation. Assuming that density is constant, the conventional 1D impedance inversion method is also applicable for 2D or 3D velocity inversion within the process of FWI. This method is not only capable of inverting for velocity, but it is also capable of retrieving anisotropic parameters relying on linearized representations of the reflection response. To eliminate the cross-talk artifacts between different parameters, I
13. Reference respiratory waveforms by minimum jerk model analysis
International Nuclear Information System (INIS)
Anetai, Yusuke; Sumida, Iori; Takahashi, Yutaka; Yagi, Masashi; Mizuno, Hirokazu; Ogawa, Kazuhiko; Ota, Seiichi
2015-01-01
Purpose: CyberKnife"® robotic surgery system has the ability to deliver radiation to a tumor subject to respiratory movements using Synchrony"® mode with less than 2 mm tracking accuracy. However, rapid and rough motion tracking causes mechanical tracking errors and puts mechanical stress on the robotic joint, leading to unexpected radiation delivery errors. During clinical treatment, patient respiratory motions are much more complicated, suggesting the need for patient-specific modeling of respiratory motion. The purpose of this study was to propose a novel method that provides a reference respiratory wave to enable smooth tracking for each patient. Methods: The minimum jerk model, which mathematically derives smoothness by means of jerk, or the third derivative of position and the derivative of acceleration with respect to time that is proportional to the time rate of force changed was introduced to model a patient-specific respiratory motion wave to provide smooth motion tracking using CyberKnife"®. To verify that patient-specific minimum jerk respiratory waves were being tracked smoothly by Synchrony"® mode, a tracking laser projection from CyberKnife"® was optically analyzed every 0.1 s using a webcam and a calibrated grid on a motion phantom whose motion was in accordance with three pattern waves (cosine, typical free-breathing, and minimum jerk theoretical wave models) for the clinically relevant superior–inferior directions from six volunteers assessed on the same node of the same isocentric plan. Results: Tracking discrepancy from the center of the grid to the beam projection was evaluated. The minimum jerk theoretical wave reduced the maximum-peak amplitude of radial tracking discrepancy compared with that of the waveforms modeled by cosine and typical free-breathing model by 22% and 35%, respectively, and provided smooth tracking for radial direction. Motion tracking constancy as indicated by radial tracking discrepancy affected by respiratory
14. Full-waveform inversion of surface waves in exploration geophysics
Science.gov (United States)
Borisov, D.; Gao, F.; Williamson, P.; Tromp, J.
2017-12-01
Full-waveform inversion (FWI) is a data fitting approach to estimate high-resolution properties of the Earth from seismic data by minimizing the misfit between observed and calculated seismograms. In land seismics, the source on the ground generates high-amplitude surface waves, which generally represent most of the energy recorded by ground sensors. Although surface waves are widely used in global seismology and engineering studies, they are typically treated as noise within the seismic exploration community since they mask deeper reflections from the intervals of exploration interest. This is mainly due to the fact that surface waves decay exponentially with depth and for a typical frequency range (≈[5-50] Hz) sample only the very shallow part of the subsurface, but also because they are much more sensitive to S-wave than P-wave velocities. In this study, we invert surface waves in the hope of using them as additional information for updating the near surface. In a heterogeneous medium, the main challenge of surface wave inversion is associated with their dispersive character, which makes it difficult to define a starting model for conventional FWI which can avoid cycle-skipping. The standard approach to dealing with this is by inverting the dispersion curves in the Fourier (f-k) domain to generate locally 1-D models, typically for the shear wavespeeds only. However this requires that the near-surface zone be more or less horizontally invariant over a sufficient distance for the spatial Fourier transform to be applicable. In regions with significant topography, such as foothills, this is not the case, so we revert to the time-space domain, but aim to minimize the differences of envelopes in the early stages of the inversion to resolve the cycle-skipping issue. Once the model is good enough, we revert to the classic waveform-difference inversion. We first present a few synthetic examples. We show that classical FWI might be trapped in a local minimum even for
15. Full Waveform Adjoint Seismic Tomography of the Antarctic Plate
Science.gov (United States)
Lloyd, A. J.; Wiens, D.; Zhu, H.; Tromp, J.; Nyblade, A.; Anandakrishnan, S.; Aster, R. C.; Huerta, A. D.; Winberry, J. P.; Wilson, T. J.; Dalziel, I. W. D.; Hansen, S. E.; Shore, P.
2017-12-01
Recent studies investigating the response and influence of the solid Earth on the evolution of the cryosphere demonstrate the need to account for 3D rheological structure to better predict ice sheet dynamics, stability, and future sea level impact, as well as to improve glacial isostatic adjustment models and more accurately measure ice mass loss. Critical rheological properties like mantle viscosity and lithospheric thickness may be estimated from shear wave velocity models that, for Antarctica, would ideally possess regional-scale resolution extending down to at least the base of the transition zone (i.e. 670 km depth). However, current global- and continental-scale seismic velocity models are unable to obtain both the resolution and spatial coverage necessary, do not take advantage of the full set of available Antarctic data, and, in most instance, employ traditional seismic imaging techniques that utilize limited seismogram information. We utilize 3-component earthquake waveforms from almost 300 Antarctic broadband seismic stations and 26 southern mid-latitude stations from 270 earthquakes (5.5 ≤ Mw ≤ 7.0) between 2001-2003 and 2007-2016 to conduct a full-waveform adjoint inversion for Antarctica and surrounding regions of the Antarctic plate. Necessary forward and adjoint wavefield simulations are performed utilizing SPECFEM3D_GLOBE with the aid of the Texas Advanced Computing Center. We utilize phase observations from seismogram segments containing P, S, Rayleigh, and Love waves, including reflections and overtones, which are autonomously identified using FLEXWIN. The FLEXWIN analysis is carried out over a short (15-50 s) and long (initially 50-150 s) period band that target body waves, or body and surface waves, respectively. As our model is iteratively refined, the short-period corner of the long period band is gradually reduced to 25 s as the model converges over 20 linearized inversion iterations. We will briefly present this new high
16. Characterization of ion beam induced nanostructures
International Nuclear Information System (INIS)
Ghatak, J.; Satpati, B.; Umananda, M.; Kabiraj, D.; Som, T.; Dev, B.N.; Akimoto, K.; Ito, K.; Emoto, T.; Satyam, P.V.
2006-01-01
Tailoring of nanostructures with energetic ion beams has become an active area of research leading to the fundamental understanding of ion-solid interactions at nanoscale regime and with possible applications in the near future. Rutherford backscattering spectrometry (RBS), high resolution transmission electron microscopy (HRTEM) and asymmetric X-ray Bragg-rocking curve experimental methods have been used to characterize ion-induced effects in nanostructures. The possibility of surface and sub-surface/interface alloying at nano-scale regime, ion-beam induced embedding, crater formation, sputtering yield variations for systems with isolated nanoislands, semi-continuous and continuous films of noble metals (Au, Ag) deposited on single crystalline silicon will be reviewed. MeV-ion induced changes in specified Au-nanoislands on silicon substrate are tracked as a function of ion fluence using ex situ TEM. Strain induced in the bulk silicon substrate surface due to 1.5 MeV Au 2+ and C 2+ ion beam irradiation is determined by using HRTEM and asymmetric Bragg X-ray rocking curve methods. Preliminary results on 1.5 MeV Au 2+ ion-induced effects in nanoislands of Co deposited on silicon substrate will be discussed
17. A Waveform Archiving System for the GE Solar 8000i Bedside Monitor.
Science.gov (United States)
Fanelli, Andrea; Jaishankar, Rohan; Filippidis, Aristotelis; Holsapple, James; Heldt, Thomas
2018-01-01
Our objective was to develop, deploy, and test a data-acquisition system for the reliable and robust archiving of high-resolution physiological waveform data from a variety of bedside monitoring devices, including the GE Solar 8000i patient monitor, and for the logging of ancillary clinical and demographic information. The data-acquisition system consists of a computer-based archiving unit and a GE Tram Rac 4A that connects to the GE Solar 8000i monitor. Standard physiological front-end sensors connect directly to the Tram Rac, which serves as a port replicator for the GE monitor and provides access to these waveform signals through an analog data interface. Together with the GE monitoring data streams, we simultaneously collect the cerebral blood flow velocity envelope from a transcranial Doppler ultrasound system and a non-invasive arterial blood pressure waveform along a common time axis. All waveform signals are digitized and archived through a LabView-controlled interface that also allows for the logging of relevant meta-data such as clinical and patient demographic information. The acquisition system was certified for hospital use by the clinical engineering team at Boston Medical Center, Boston, MA, USA. Over a 12-month period, we collected 57 datasets from 11 neuro-ICU patients. The system provided reliable and failure-free waveform archiving. We measured an average temporal drift between waveforms from different monitoring devices of 1 ms every 66 min of recorded data. The waveform acquisition system allows for robust real-time data acquisition, processing, and archiving of waveforms. The temporal drift between waveforms archived from different devices is entirely negligible, even for long-term recording.
18. Reliability of pressure waveform analysis to determine correct epidural needle placement in labouring women.
Science.gov (United States)
Al-Aamri, I; Derzi, S H; Moore, A; Elgueta, M F; Moustafa, M; Schricker, T; Tran, D Q
2017-07-01
Pressure waveform analysis provides a reliable confirmatory adjunct to the loss-of-resistance technique to identify the epidural space during thoracic epidural anaesthesia, but its role remains controversial in lumbar epidural analgesia during labour. We performed an observational study in 100 labouring women of the sensitivity and specificity of waveform analysis to determine the correct location of the epidural needle. After obtaining loss-of-resistance, the anaesthetist injected 5 ml saline through the epidural needle (accounting for the volume already used in the loss-of-resistance). Sterile extension tubing, connected to a pressure transducer, was attached to the needle. An investigator determined the presence or absence of a pulsatile waveform, synchronised with the heart rate, on a monitor screen that was not in the view of the anaesthetist or the parturient. A bolus of 4 ml lidocaine 2% with adrenaline 5 μg.ml -1 was administered, and the epidural block was assessed after 15 min. Three women displayed no sensory block at 15 min. The results showed: epidural block present, epidural waveform present 93; epidural block absent, epidural waveform absent 2; epidural block present, epidural waveform absent 4; epidural block absent, epidural waveform present 1. Compared with the use of a local anaesthetic bolus to ascertain the epidural space, the sensitivity, specificity, positive and negative predictive values of waveform analysis were 95.9%, 66.7%, 98.9% and 33.3%, respectively. Epidural waveform analysis provides a simple adjunct to loss-of-resistance for confirming needle placement during performance of obstetric epidurals, however, further studies are required before its routine implementation in clinical practice. © 2017 The Association of Anaesthetists of Great Britain and Ireland.
19. Doppler waveform study as indicator of change of portal pressure after administration of octreotide
Science.gov (United States)
Haider, Shahbaz; Hussain, Qurban; Tabassum, Sumera; Hussain, Bilal; Durrani, Muhammad Rasheed; Ahmed, Fayyaz
2016-01-01
Objective: To estimate the effect of portal pressure lowering drug ‘octreotide’, by observing the Doppler waveform before and after the administration of intravenous bolus of octreotide and thus to assess indirectly its efficacy to lower the portal pressure. Methods: This quassi experimental study was carried out in Medical Department in collaboration with Radiology Department of Jinnah Postgraduate Medical Center Karachi Pakistan from September 10, 2015 to February 5, 2016. Cases were selected from patients admitted in Medical Wards and those attending Medical OPD. Diagnosis of cirrhosis was confirmed by Clinical Examination and Lab & Imaging investigation in Medical Department. Doppler waveform study was done by experienced radiologist in Radiology Department before and after administration of octreotide. Doppler signals were obtained from the right hepatic vein. Waveform tracings were recorded for five seconds and categorized as ‘monophasic’, ‘biphasic’ and ‘triphasic’. Waveform changes from one waveform to other were noted and analyzed. Results: Significant change i.e. from ‘monophasic’ to ‘biphasic’ or ‘biphasic’ to ‘triphasic’ was seen in 56% cases while ‘monophasic’ to ‘triphasic’ was seen in 20% cases. No change was seen in 24% cases. Improvement in waveform reflects lowering of portal vein pressure. Conclusion: Non invasive Hepatic vein Doppler waveform study showed improvement in Doppler waveform after administration of octreotide in 76% cases. Doppler waveform study has the potential of becoming non invasive ‘follow up tool’ of choice for assessing portal pressure in patients having variceal bleed due to portal hypertension. PMID:27648043
20. Ion movie camera for particle-beam-fusion experiments
International Nuclear Information System (INIS)
Stygar, W.A.; Mix, L.P.; Leeper, R.J.; Maenchen, J.; Wenger, D.F.; Mattson, C.R.; Muron, D.J.
1992-01-01
A camera with a 3 ns time resolution and a continuous (>100 ns) record length has been developed to image a 10 12 --10 13 W/cm 2 ion beam for inertial-confinement-fusion experiments. A thin gold Rutherford-scattering foil placed in the path of the beam scatters ions into the camera. The foil is in a near-optimized scattering geometry and reduces the beam intensity∼seven orders of magnitude. The scattered ions are pinhole imaged onto a 2D array of 39 p-i-n diode detectors; outputs are recorded on LeCroy 6880 transient-waveform digitizers. The waveforms are analyzed and combined to produce a 39-pixel movie which can be displayed on an image processor to provide time-resolved horizontal- and vertical-focusing information
1. Direct catalytic asymmetric aldol-Tishchenko reaction.
Science.gov (United States)
Gnanadesikan, Vijay; Horiuchi, Yoshihiro; Ohshima, Takashi; Shibasaki, Masakatsu
2004-06-30
A direct catalytic asymmetric aldol reaction of propionate equivalent was achieved via the aldol-Tishchenko reaction. Coupling an irreversible Tishchenko reaction to a reversible aldol reaction overcame the retro-aldol reaction problem and thereby afforded the products in high enantio and diastereoselectivity using 10 mol % of the asymmetric catalyst. A variety of ketones and aldehydes, including propyl and butyl ketones, were coupled efficiently, yielding the corresponding aldol-Tishchenko products in up to 96% yield and 95% ee. Diastereoselectivity was generally below the detection limit of 1H NMR (>98:2). Preliminary studies performed to clarify the mechanism revealed that the aldol products were racemic with no diastereoselectivity. On the other hand, the Tishchenko products were obtained in a highly enantiocontrolled manner.
2. Brownian Motion of Asymmetric Boomerang Colloidal Particles
Science.gov (United States)
Chakrabarty, Ayan; Konya, Andrew; Wang, Feng; Selinger, Jonathan; Sun, Kai; Wei, Qi-Huo
2014-03-01
We used video microscopy and single particle tracking to study the diffusion and local behaviors of asymmetric boomerang particles in a quasi-two dimensional geometry. The motion is biased towards the center of hydrodynamic stress (CoH) and the mean square displacements of the particles are linear at short and long times with different diffusion coefficients and in the crossover regime it is sub-diffusive. Our model based on Langevin theory shows that these behaviors arise from the non-coincidence of the CoH with the center of the body. Since asymmetric boomerangs represent a class of rigid bodies of more generals shape, therefore our findings are generic and true for any non-skewed particle in two dimensions. Both experimental and theoretical results will be discussed.
3. Dynamics of asymmetric kinetic Ising systems revisited
International Nuclear Information System (INIS)
Huang, Haiping; Kabashima, Yoshiyuki
2014-01-01
The dynamics of an asymmetric kinetic Ising model is studied. Two schemes for improving the existing mean-field description are proposed. In the first scheme, we derive the formulas for instantaneous magnetization, equal-time correlation, and time-delayed correlation, considering the correlation between different local fields. To derive the time-delayed correlation, we emphasize that the small-correlation assumption adopted in previous work (Mézard and Sakellariou, 2011 J. Stat. Mech. L07001) is in fact not required. To confirm the prediction efficiency of our method, we perform extensive simulations on single instances with either temporally constant external driving fields or sinusoidal external fields. In the second scheme, we develop an improved mean-field theory for instantaneous magnetization prediction utilizing the notion of the cavity system in conjunction with a perturbative expansion approach. Its efficiency is numerically confirmed by comparison with the existing mean-field theory when partially asymmetric couplings are present. (paper)
4. Bianisotropic metamaterials based on twisted asymmetric crosses
International Nuclear Information System (INIS)
Reyes-Avendaño, J A; Sampedro, M P; Juárez-Ruiz, E; Pérez-Rodríguez, F
2014-01-01
The effective bianisotropic response of 3D periodic metal-dielectric structures, composed of crosses with asymmetrically-cut wires, is investigated within a general homogenization theory using the Fourier formalism and the form-factor division approach. It is found that the frequency dependence of the effective permittivity for a system of periodically-repeated layers of metal crosses exhibits two strong resonances, whose separation is due to the cross asymmetry. Besides, bianisotropic metamaterials, having a base of four twisted asymmetric crosses, are proposed. The designed metamaterials possess negative refractive index at frequencies determined by the cross asymmetry, the gap between the arms of adjacent crosses lying on the same plane, and the type of Bravais lattice. (papers)
5. Improved DFIG Capability during Asymmetrical Grid Faults
DEFF Research Database (Denmark)
Zhou, Dao; Blaabjerg, Frede
2015-01-01
In the wind power application, different asymmetrical types of the grid fault can be categorized after the Y/d transformer, and the positive and negative components of a single-phase fault, phase-to-phase fault, and two-phase fault can be summarized. Due to the newly introduced negative and even...... the natural component of the Doubly-Fed Induction Generator (DFIG) stator flux during the fault period, their effects on the rotor voltage can be investigated. It is concluded that the phase-to-phase fault has the worst scenario due to its highest introduction of the negative stator flux. Afterwards......, the capability of a 2 MW DFIG to ride through asymmetrical grid faults can be estimated at the existing design of the power electronics converter. Finally, a control scheme aimed to improve the DFIG capability is proposed and the simulation results validate its feasibility....
6. The Influence of Measurement Methodology on the Accuracy of Electrical Waveform Distortion Analysis
Science.gov (United States)
Bartman, Jacek; Kwiatkowski, Bogdan
2018-04-01
The present paper covers a review of documents that specify measurement methods of voltage waveform distortion. It also presents measurement stages of waveform components that are uncommon in the classic fundamentals of electrotechnics and signal theory, including the creation process of groups and subgroups of harmonics and interharmonics. Moreover, the paper discusses selected distortion factors of periodic waveforms and presents analyses that compare the values of these distortion indices. The measurements were carried out in the cycle per cycle mode and the measurement methodology that was used complies with the IEC 61000-4-7 norm. The studies showed significant discrepancies between the values of analyzed parameters.
7. 100 GHz pulse waveform measurement based on electro-optic sampling
Science.gov (United States)
Feng, Zhigang; Zhao, Kejia; Yang, Zhijun; Miao, Jingyuan; Chen, He
2018-05-01
We present an ultrafast pulse waveform measurement system based on an electro-optic sampling technique at 1560 nm and prepare LiTaO3-based electro-optic modulators with a coplanar waveguide structure. The transmission and reflection characteristics of electrical pulses on a coplanar waveguide terminated with an open circuit and a resistor are investigated by analyzing the corresponding time-domain pulse waveforms. We measure the output electrical pulse waveform of a 100 GHz photodiode and the obtained rise times of the impulse and step responses are 2.5 and 3.4 ps, respectively.
8. Variation of Pressure Waveforms in Measurements of Extracorporeal Shock Wave Lithotripter
Science.gov (United States)
Inose, Naoto; Ide, Masao
1993-05-01
In this paper, we describe measurement of variation in pressure waveforms of the acoustic field of an extra-corporeal shock-wave lithotripter (ESWL). Variations in the measured acoustic fields and pressure waveform of an underwater spark-gap-type ESWL with an exhausted spark plug electrode have been reported by researchers using crystal sensors. If the ESWL spark plugs become exhausted, patients feel pain during kidney, biliary stone disintegration. We studied the relationship between exhaustion of electrodes and the variation of pressure waveforms and shock-wave fields of the ESWL using a newly developed hydrophone.
9. Extracting structural land cover components using small-footprint waveform LDAR data
CSIR Research Space (South Africa)
McGlinchy, J
2010-07-01
Full Text Available .e., without vertical interactions. Three measurements were taken from the waveform once this component was removed. They are defined as ?Road Ratio?, ?Leftover?, and ?Ratio Removed?. ?Road Ratio? is measured as the ratio of an amplitude scaled dirt road... sample to an original dirt road waveform sample extracted from LU8. ?Leftover? is measured as the ratio of the sum of what remains in the ground pulse to the sum of these same points in the original waveform. ?Ratio Removed? is measured simply...
10. Asymmetric volatility connectedness on the forex market
Czech Academy of Sciences Publication Activity Database
Baruník, Jozef; Kočenda, Evžen; Vácha, Lukáš
2017-01-01
Roč. 77, č. 1 (2017), s. 39-56 ISSN 0261-5606 R&D Projects: GA ČR(CZ) GA16-14179S Institutional support: RVO:67985556 Keywords : volatility * connectedness * asymmetric effects Subject RIV: AH - Economics OBOR OECD: Finance Impact factor: 1.853, year: 2016 http://library.utia.cas.cz/separaty/2017/E/barunik-0478477.pdf
11. Magnetic properties of strongly asymmetric nuclear matter
International Nuclear Information System (INIS)
Kutschera, M.; Wojcik, W.
1988-01-01
We investigate stability of neutron matter containing a small proton admixture with respect to spin fluctuations. We establish conditions under which strongly asymmetric nuclear matter could acquire a permanent magnetization. It is shown that if the protons are localized, the system becomes unstable to spin fluctuations for arbitrarily weak proton-neutron spin interactions. For non-localized protons there exists a threshold value of the spin interaction above which the system can develop a spontaneous polarization. 12 refs., 2 figs. (author)
12. Isospin dependent properties of asymmetric nuclear matter
OpenAIRE
Chowdhury, P. Roy; Basu, D. N.; Samanta, C.
2009-01-01
The density dependence of nuclear symmetry energy is determined from a systematic study of the isospin dependent bulk properties of asymmetric nuclear matter using the isoscalar and the isovector components of density dependent M3Y interaction. The incompressibility $K_\\infty$ for the symmetric nuclear matter, the isospin dependent part $K_{asy}$ of the isobaric incompressibility and the slope $L$ are all in excellent agreement with the constraints recently extracted from measured isotopic de...
13. Asymmetric flow events in a VEER 1000
International Nuclear Information System (INIS)
Horak, W.C.; Kennett, R.J.; Shier, W.; Guppy, J.G.
1992-07-01
This paper describes the simulation of asymmetric loss of flow events in Russian designed VVER-1000 reactors using the RETRAN-02 Mod4 computer code. VVER-1000 reactors have significant differences from United States pressurized water reactors including multi-level emergency response systems and plant operation at reduced power levels with one or more main circulation pumps inoperable. The results of these simulations are compared to similar analyses done by the designers for the Rovno plant
14. Two particle states in an asymmetric box
OpenAIRE
Li, Xin; Liu, Chuan
2004-01-01
The exact two-particle energy eigenstates in an asymmetric rectangular box with periodic boundary conditions in all three directions are studied. Their relation with the elastic scattering phases of the two particles in the continuum are obtained. These results can be viewed as a generalization of the corresponding formulae in a cubic box obtained by L\\"uscher before. In particular, the s-wave scattering length is related to the energy shift in the finite box. Possible applications of these f...
15. Symmetric vs. asymmetric punishment regimes for bribery
OpenAIRE
Engel, Christoph; Goerg, Sebastian J.; Yu, Gaoneng
2012-01-01
In major legal orders such as UK, the U.S., Germany, and France, bribers and recipients face equally severe criminal sanctions. In contrast, countries like China, Russia, and Japan treat the briber more mildly. Given these differences between symmetric and asymmetric punishment regimes for bribery, one may wonder which punishment strategy is more effective in curbing corruption. For this purpose, we designed and ran a lab experiment in Bonn (Germany) and Shanghai (China) with exactly the same...
16. The separation of control variables in an H/sup /minus// ion source
International Nuclear Information System (INIS)
Bowling, P.S.; Brown, S.K.
1988-01-01
This paper describes a successful methodology which was used to classify a series if waveforms taken from a 100 ma H/sup /minus// ion source at Los Alamos. The series of 260 waveforms was divided into a ''training'' set and a ''test'' set. A sequence of mathematical transformations was performed on the ''training'' waveforms data and then it was subjected to discriminant analysis. The analysis generates a set of filters which will allow classification of an unknown waveform in the ''test'' set as being either stable or unstable; if stable, whether optimal or not; if not optimal, which of the six control parameters should be adjusted to bring it to an optimal condition. We have found that the probability of successful classification using this methodology is 91.5%. 3 refs., 4 figs., 2 tabs
17. Predicting tensorial electrophoretic effects in asymmetric colloids
Science.gov (United States)
Mowitz, Aaron J.; Witten, T. A.
2017-12-01
We formulate a numerical method for predicting the tensorial linear response of a rigid, asymmetrically charged body to an applied electric field. This prediction requires calculating the response of the fluid to the Stokes drag forces on the moving body and on the countercharges near its surface. To determine the fluid's motion, we represent both the body and the countercharges using many point sources of drag known as Stokeslets. Finding the correct flow field amounts to finding the set of drag forces on the Stokeslets that is consistent with the relative velocities experienced by each Stokeslet. The method rigorously satisfies the condition that the object moves with no transfer of momentum to the fluid. We demonstrate that a sphere represented by 1999 well-separated Stokeslets on its surface produces flow and drag force like a solid sphere to 1% accuracy. We show that a uniformly charged sphere with 3998 body and countercharge Stokeslets obeys the Smoluchowski prediction [F. Morrison, J. Colloid Interface Sci. 34, 210 (1970), 10.1016/0021-9797(70)90171-2] for electrophoretic mobility when the countercharges lie close to the sphere. Spheres with dipolar and quadrupolar charge distributions rotate and translate as predicted analytically to 4% accuracy or better. We describe how the method can treat general asymmetric shapes and charge distributions. This method offers promise as a way to characterize and manipulate asymmetrically charged colloid-scale objects from biology (e.g., viruses) and technology (e.g., self-assembled clusters).
18. Asymmetric threat data mining and knowledge discovery
Science.gov (United States)
Gilmore, John F.; Pagels, Michael A.; Palk, Justin
2001-03-01
Asymmetric threats differ from the conventional force-on- force military encounters that the Defense Department has historically been trained to engage. Terrorism by its nature is now an operational activity that is neither easily detected or countered as its very existence depends on small covert attacks exploiting the element of surprise. But terrorism does have defined forms, motivations, tactics and organizational structure. Exploiting a terrorism taxonomy provides the opportunity to discover and assess knowledge of terrorist operations. This paper describes the Asymmetric Threat Terrorist Assessment, Countering, and Knowledge (ATTACK) system. ATTACK has been developed to (a) data mine open source intelligence (OSINT) information from web-based newspaper sources, video news web casts, and actual terrorist web sites, (b) evaluate this information against a terrorism taxonomy, (c) exploit country/region specific social, economic, political, and religious knowledge, and (d) discover and predict potential terrorist activities and association links. Details of the asymmetric threat structure and the ATTACK system architecture are presented with results of an actual terrorist data mining and knowledge discovery test case shown.
19. Diagnostic implications of asymmetrical mammographic patterns
International Nuclear Information System (INIS)
Asenjo, M.; Ania, B.J.
1997-01-01
To analyze the effect of asymmetrical mammographic patterns of the diagnosis of breast cancer. In a series of 6, 476 patients referred to a Breast Imaging Diagnosis Unit, we excluded males, women with previous breast surgery, and cases in which mammography was not performed, which left 5,203 women included. Each breast was classified according to one of four patterns of mammographic parenchymal density. Asymmetry was considered to exist when a patient's breasts had different patterns. Breast cancer was confirmed histologically in 282 (5.4%) women. The mammographic pattern was asymmetrical in 8% of the women with cancer and in 2% of the women without cancer (p<0.001). Fine-needle aspiration biopsy was performed in 78% and 96% (p=0.04), respectively, of the women with and without mammographic asymmetry who had neoplasms, and in 33% and 22% (p=0.02), respectively, of the women with and without mammographic asymmetry who did not have neoplasms. Asymmetrical mammographic pattern was four times more frequent in the women with breast cancer. This asymmetry decreased the frequency of needle biopsy in women with cancer, but increased the frequency of needle biopsy in women without cancer. (Author) 11 refs
20. Hadron scattering in an asymmetric box
International Nuclear Information System (INIS)
Li Xin; Chen Ying; Meng Guozhan; Feng Xu; Gong Ming; He Song; Li Gang; Liu Chuan; Liu Yubin; Ma Jianping; Meng Xiangfei; Shen Yan; Zhang Jianbo
2007-01-01
We propose to study hadron-hadron scattering using lattice QCD in an asymmetric box which allows one to access more non-degenerate low-momentum modes for a given volume. The conventional Luescher's formula applicable in a symmetric box is modified accordingly. To illustrate the feasibility of this approach, pion-pion elastic scattering phase shifts in the I = 2, J = 0 channel are calculated within quenched approximation using improved gauge and Wilson fermion actions on anisotropic lattices in an asymmetric box. After the chiral and continuum extrapolation, we find that our quenched results for the scattering phase shifts in this channel are consistent with the experimental data when the three-momentum of the pion is below 300MeV. Agreement is also found when compared with previous theoretical results from lattice and other means. Moreover, with the usage of asymmetric volume, we are able to compute the scattering phases in the low-momentum range (pion three momentum less than about 350MeV in the center of mass frame) for over a dozen values of the pion three-momenta, much more than using the conventional symmetric box with comparable volume
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https://istopdeath.com/solve-for-x-log-base-4-of-8x/
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# Solve for x log base 4 of 8=x
Rewrite the equation as .
Logarithm base of is .
Rewrite as an equation.
Rewrite in exponential form using the definition of a logarithm. If and are positive real numbers and does not equal , then is equivalent to .
Create expressions in the equation that all have equal bases.
Rewrite as .
Since the bases are the same, then two expressions are only equal if the exponents are also equal.
Solve for .
The variable is equal to .
The result can be shown in multiple forms.
Exact Form:
Decimal Form:
Mixed Number Form:
Solve for x log base 4 of 8=x
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http://mathhelpforum.com/geometry/217852-point-infinity-elliptic-curve.html
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## Point of infinity on an elliptic curve?
How to find the point of infinity on an elliptic curve y^2=X^3-5 ?
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https://manual.q-chem.com/5.2/Ch8.S3.SS1.html
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# 8.3.1 Customization
Q-Chem offers a number of standard and special customization features. One of the most important is that of supplying additional diffuse functions. Diffuse functions are often important for studying anions and excited states of molecules, and for the latter several sets of additional diffuse functions may be required. These extra diffuse functions can be generated from the standard diffuse functions by applying a scaling factor to the exponent of the original diffuse function. This yields a geometric series of exponents for the diffuse functions which includes the original standard functions along with more diffuse functions.
When using very large basis sets, especially those that include many diffuse functions, or if the system being studied is very large, linear dependence in the basis set may arise. This results in an over-complete description of the space spanned by the basis functions, and can cause a loss of uniqueness in the molecular orbital coefficients. Consequently, the SCF may be slow to converge or behave erratically. Q-Chem will automatically check for linear dependence in the basis set, and will project out the near-degeneracies, if they exist. This will result in there being slightly fewer molecular orbitals than there are basis functions. Q-Chem checks for linear-dependence by considering the eigenvalues of the overlap matrix. Very small eigenvalues are an indication that the basis set is close to being linearly dependent. The size at which the eigenvalues are considered to be too small is governed by the \$rem variable BASIS_LIN_DEP_THRESH. By default this is set to 6, corresponding to a threshold of $10^{-6}$. This has been found to give reliable results, however, if you have a poorly behaved SCF, and you suspect there maybe linear dependence in you basis, the threshold should be increased.
PRINT_GENERAL_BASIS
Controls print out of built in basis sets in input format
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
TRUE Print out standard basis set information FALSE Do not print out standard basis set information
RECOMMENDATION:
Useful for modification of standard basis sets.
BASIS_LIN_DEP_THRESH
Sets the threshold for determining linear dependence in the basis set
TYPE:
INTEGER
DEFAULT:
6 Corresponding to a threshold of $10^{-6}$
OPTIONS:
$n$ Sets the threshold to $10^{-n}$
RECOMMENDATION:
Set to 5 or smaller if you have a poorly behaved SCF and you suspect linear dependence in you basis set. Lower values (larger thresholds) may affect the accuracy of the calculation.
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https://worldwidescience.org/topicpages/l/lill+neste+mesilane.html
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#### Sample records for lill neste mesilane
1. Den Lille Leder
DEFF Research Database (Denmark)
Juhl, Martin; Ussing, Lene Faber
En lille lommebog, der i fem trin hjælper dig som projektleder til succesfulde projekter i entreprenørbranchen. "Den lille leder" indeholder udvalgte ledelsesteorier, der er relevante for projektledere i byggebranchen.......En lille lommebog, der i fem trin hjælper dig som projektleder til succesfulde projekter i entreprenørbranchen. "Den lille leder" indeholder udvalgte ledelsesteorier, der er relevante for projektledere i byggebranchen....
2. Den lille levnedsmiddeltabel
DEFF Research Database (Denmark)
Saxholt, Erling; Fagt, Sisse; Matthiessen, Jeppe;
Den lille levnedsmiddeltabel er en oversigt over indholdet af næringsstoffer i næsten 600 af de mest anvendte fødevarer i den danske kost. Herudover rummer bogen anvisninger til anvendelsen af fødevaredata....
3. Le Grand Lille (Frans)
NARCIS (Netherlands)
Bussiere, Eric
2001-01-01
Lille occupe une place particuliere dans l'Europe des metropoles. Fille de l'eau dont elle tire son nom, Insula, son histoire est d'abord celle d'une lutte incessante pour domestiquer une nature inhospitaliere et transformer un site ingrat en un paysage urbain attractif. Se situer au coeur de l'echi
4. Den lille levnedsmiddeltabel
DEFF Research Database (Denmark)
Saxholt, Erling; Fagt, Sisse; Matthiessen, Jeppe
Den lille levnedsmiddeltabel er en oversigt over indholdet af næringsstoffer i næsten 600 af de mest anvendte fødevarer i den danske kost. Herudover rummer bogen anvisninger til anvendelsen af fødevaredata....
5. Kild Eestit Lille'is
Index Scriptorium Estoniae
2008-01-01
25. aprillist 10. maini Põhja-Prantsusmaal Lille'is toimuvast Eesti kultuurifestivalist "Vivre l'Estonie", millega tähistatakse Eesti Vabariigi 90. sünnipäeva. Toimub Aldo Järvsoo rahvarõivastest inspireeritud moeetendus, esinevad Leigarid, Ro:Toro, Brüsseli eestlaste segakoor Beene ja laulja Lembe Lokk. Filmiõhtul Ilmar Raagi film "Klass" ning James Tusty film "Laulev revolutsioon", Liina Keevalliku installatsioonid
6. Kunstimuuseum Lille'is (Prantsusmaa) / Triin Ojari
Index Scriptorium Estoniae
Ojari, Triin, 1974-
1998-01-01
Lille'i 19. sajandil ehitatud kunstimuuseumi hoonele uue tiiva lisamisest ja hoone rekonstrueerimisest. Uus tiib on kuuekorruseline klaaskuup. Õhuline fassaad koosneb mitmest kihist, mis kokku mängivad. Arhitektid Jean Marc Ibos ja Myrto Vitart
7. Kurja lilled, kurja kunstnikud / Teet Veispak
Index Scriptorium Estoniae
Veispak, Teet, 1955-
2006-01-01
Eesti Kunstnike Liidu 6. aastanäituse projekt "Kurja lilled" Hobusepea galeriis, Draakoni galeriis ja HOP galeriis, kuraator Elin Kard. Eksponeeritakse Kaido Ole, Marko Mäetamme, Jüri Ojaveri, Marco Laimre, Kaarel Eelma, Sirja-Liisa Vahtra, Jaan Paavle, Kristin Kalamehe, Liina Siibi, Merike Estna, Maksim Surini, Kadi Estlandi, Killu Sukmiti jt. töid
8. Lille mäele tuleb suveks Flauerpauer / Jaanika Meier
Index Scriptorium Estoniae
Meier, Jaanika
2008-01-01
Tartus Lille Maja hoovis avatakse suvekohvik Flauerpauer. Kohviku väliskujunduse autoriteks on Tartu kõrgema kunstikooli tudengid Tiit Joala ja Oliver Kuusmann, sisekujunduse autoriks Tallinna Ülikooli üliõpilane Kudrun Vunk. Kommenteerib Hele Riit-Vällik
9. Uhiuus orkester Tallinn Sinfonietta / Ivo Lille ja Risto Joost ; intervjueerinud Kristina Kõrver
Index Scriptorium Estoniae
Lille, Ivo, 1977-
2009-01-01
Kontserdiagentuurist HIMusic Agency ja Tallinn Sinfoniettast räägivad dirigent R. Joost ja I. Lille. Avakontserdist Vene Kultuurikeskuses, kus oli kavas Mozarti sümfooniad 1, 10 ja 40 ning kontsertaariad bulgaaria soprani Sonya Youncheva esituses
10. Uhiuus orkester Tallinn Sinfonietta / Ivo Lille ja Risto Joost ; intervjueerinud Kristina Kõrver
Index Scriptorium Estoniae
Lille, Ivo, 1977-
2009-01-01
Kontserdiagentuurist HIMusic Agency ja Tallinn Sinfoniettast räägivad dirigent R. Joost ja I. Lille. Avakontserdist Vene Kultuurikeskuses, kus oli kavas Mozarti sümfooniad 1, 10 ja 40 ning kontsertaariad bulgaaria soprani Sonya Youncheva esituses
11. "Ma sinna istutaks need lilled punased..." : [luuletused] / [Ptshelovodova, Nadezhda] Muš Nadii ; tlk. Arvo Valton
Index Scriptorium Estoniae
2006-01-01
Sisu: "Ma sinna istutaks need lilled punased..." ; "Ei kõik hinged tõuse taevasse..." ; Kuum öö ; Kas tunned ; Ojamaa ; Magnoolia ; 24.02.2005 ; Päike vaatab tagasi. Luuletused paralleelselt udmurdi ja eesti keeles
12. Kõrged külalised Lille'i ülikoolist / Risto Mets
Index Scriptorium Estoniae
Mets, Risto
2007-01-01
Maaülikooliga käisid tutvumas ja koostöösidemeid sõlmimas Prantsusmaa Lille'i ülikooli õppeprorektor Francis Meilliez, välissuhete prorektor Jacky Lesage ning õppeosakonna juhataja Arnaud Gauthier
13. Erotitsheski konspekt / Vladimir Makarenko, Mihhail Duhhomjonok, Ado Lill ; interv. Galina Balashova
Index Scriptorium Estoniae
2002-01-01
Näitusel "Art-delikatess" osalevate kunstnikega nende töödest erootikanäitusel galeriis Magnon Tallinnas. Vestlevad Vladimir Makarenko, Mihhail Duhhomjonok, Ado Lill, Valeri Vinogradov, Anatoli Strahhov, Slava Semerikov, Andrei Balashov
14. [Publications of medical thesis defended in Lille school of medicine].
Science.gov (United States)
Benotmane, Ilies; Glatz, Nicolas; Bihan, Solenn; Legrand, Fanny; Gosset, Didier; Boulanger, Eric
2012-07-01
The purpose of this study was to determine the future, in terms of scientific publication, of medical thesis (MT) defended in the Medical School of Lille 2 University (MSL2U) between January 1st, 2001 and December 31st, 2007. The collection of MT published as a corresponding scientific article was realized from PubMed(®). For every corresponding article, we determined the journal Impact Factor (IF), the language of publication and the rank of the student and his MT director in the author list. Analyses were also realized according to the group of speciality of the TM. In all, 11.3% of the 2150 MT defended in the MSL2U were followed up by a scientific publication. The average IF was 2.32 with a median at 1.75 and extreme values from 0 to 14.78. Seventy percent of the articles were published in English. The rank of the student was placed before his MT director (2.06 vs. 3.15). The MT defended by students in the field of medical specialities presented the highest rate of publication (25.1%). The general medicine was the second speciality the most productive in term of number of published articles (n=49) after medical specialities (n=103). The MT director and the PhD students must be more motivated to publish their results. The value of 11.3% could be considered as weak but, because of a huge lack of references, it is impossible to compare our results to those of other French medical schools. It remains important to reform the objectives and the modalities of the writing of a MT: should we not have to turn to thesis called "on article"? Copyright © 2012. Published by Elsevier Masson SAS.
15. Triangular Nests!
Science.gov (United States)
Powell, R. I.
2002-01-01
Shows how integer-sided triangles can be nested, each nest having a single enclosing isosceles triangle. Brings to light what can be seen as a relatively simple generalization of Pythagoras' theorem, a result that should be readily accessible to many secondary school pupils. (Author/KHR)
16. Le mobilier domestique à Lille au XVIIe siècle
Directory of Open Access Journals (Sweden)
Odile Canneva-Tétu
2012-04-01
Full Text Available L'exposition « Lille au XVIIe siècle » présentée au musée des Beaux-Arts de Lille du 15 septembre au 27 décembre 2000 a fourni l'occasion de dresser un premier état des connaissances sur le mobilier civil lillois entre 1600 et 1715. Ce court essai s'appuie sur quelques exemples recensés dans les collections publiques lilloises.
17. Hawaii ESI: NESTS (Nest Points)
Data.gov (United States)
National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for seabird nesting colonies in coastal Hawaii. Vector points in this data set represent locations of...
18. Louisiana ESI: NESTS (Nest Points)
Data.gov (United States)
National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for seabird and wading bird nesting colonies in coastal Louisiana. Vector points in this data set represent...
19. Mellem behovsorientering og regulering - diskurser om det omsorg for det lille barn
DEFF Research Database (Denmark)
Pedersen, Oline
2013-01-01
En artikel der på baggrund af feltarbejde i den danske sundhedsplejen søger at indfange, hvor diskursen om omsorg for det lille barn befinder sig i spændingsfeltet mellem at regulere barnet eller at følge dets signaler og behov....
20. Lille SOL - Sprog og leg for de yngste 0-3 år
DEFF Research Database (Denmark)
Bylander, Helle Iben
Lille Sol – Sprog og leg for de yngste er en inspirationskilde til en lang række lege, som børn og voksne kan udvikle i fællesskab. Indgangsvinklen er at videreudvikle sprogmiljøer og afsætte tid og rammer til leg, der kan virke befordrende for børns sproglige udvikling. Som udgangspunkt for valget...
1. From bibliometric analysis to research policy: the use of SIGAPS in Lille University Hospital.
Science.gov (United States)
Devos, Patrick; Lefranc, Helene; Dufresne, Eric; Beuscart, Regis
2006-01-01
In French hospitals, the progressive setting up of the new rating systems has obliged the university hospitals to justify a certain amount of activities such as research, training or moreover recourse, which are specific missions of the university hospitals. In order to justify research activities, the Lille University Hospital has developed for now three years SIGAPS, a full-web bibliometric software which census and analyse, the scientific publications referenced in the Medline database. After data downloading, each article is classified on a 6 levels "quality scale derived from the impact factors. The system then performs, for a researcher or a team, a report allowing a quantitative and qualitative analysis. Started in Lille in November 2004, the inventory and analysis of data is now ending. For the period 2001-2004, 2814 articles have been published in 700 different journals. The total number of articles increased from 688 in 2001 to 757 in 2004. The mean impact factor was equal to 2.26 and 15.5 % of articles were classified as A, 20.9% as B. Those results confirm the high level of research of the University Hospital of Lille, in agreement with two other national studies which ranks our establishment at the 6th position for medical research activities among the French University Hospitals. Currently a similar evaluation has now began in the 9 other university hospital which have subscribed to the SIGAPS project. We works currently on new indicators as patents, thesis or conferences, or access to other databases as Sciencedirect or Scopus via the RIS format. The next step in the project is the implementation of a meta-base which will federate the information provided by each SIGAPS system. This meta-base will then allow us to perform comparisons between different hospitals, determine the national "sites of excellence" and create some clinical and research networks.
2. American Samoa ESI: NESTS (Nest Points)
Data.gov (United States)
National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for nesting birds in American Samoa. Vector points in this data set represent locations of nesting...
3. [On Michel Foucault's unpublished lectures on Ludwig Binswanger's existential analysis (Lille 1953-54)].
Science.gov (United States)
Basso, Elisabetta
2016-12-01
This paper aims to analyze Michel Foucault's position toward phenomenological psychology and psychopathology during the 1950s, in light of the new documentary sources available today. Our investigation is especially focused on one of the courses given by Foucault at the University of Lille between 1952 and 1954, namely, the course on "Binswanger and phenomenology" (1953-54). The analysis of this course, which was conceived by Foucault within the context of a philosophical reflection on the anthropological problem of psychopathology, will finally allow us to re-ascribe Foucault the place he deserves in the field of "philosophy of psychiatry".
4. Laval on mürri ja kaneeli hõngu / Märt-Matis Lill ; interv. Tiit Tuumalu
Index Scriptorium Estoniae
Lill, Märt-Matis, 1975-
2005-01-01
Hollandi trupi Club Guy kontsertetendusest "Myrrh and Cinnamon" Kanuti Gildi saalis., mis tuli esmakodselt ettekandele A. Pärdile pühendatud festivalil "Aestonishing music", kontsertetenduses kasutatud eesti heliloojate Pärdi, Tüüri, Sumera, Lille muusikast. Koreograafid G. Welzman ja R. Haver
5. Laval on mürri ja kaneeli hõngu / Märt-Matis Lill ; interv. Tiit Tuumalu
Index Scriptorium Estoniae
Lill, Märt-Matis, 1975-
2005-01-01
Hollandi trupi Club Guy kontsertetendusest "Myrrh and Cinnamon" Kanuti Gildi saalis., mis tuli esmakodselt ettekandele A. Pärdile pühendatud festivalil "Aestonishing music", kontsertetenduses kasutatud eesti heliloojate Pärdi, Tüüri, Sumera, Lille muusikast. Koreograafid G. Welzman ja R. Haver
6. Two light automated transport systems in course of construction: Lille and Vancouver
Energy Technology Data Exchange (ETDEWEB)
Barwell, F.T.
1982-10-01
Noise and vibration control in light-electric-rail systems can be mitigated by using either the French system of pneumatic tires or the special vehicles developed to improve flange contact between steel wheels and rail as the Canadians have done in Vancouver. The pneumatic tires used in Lille, France also have the advantage of better adhesion on steep grades, but the possibility of hydroplaning makes it necessary to use a special tread pattern or to operate under cover. The Vancouver system overcomes the problem on curves with radial axles and during braking with linear induction motors to propel and brake the wheels. Both approaches appear to have provided environmental solutions and met local requirements for unmanned transit systems. 7 references, 7 figures, 1 table. (DCK)
7. Community mental health service: an experience from the East Lille, France
Directory of Open Access Journals (Sweden)
Jean Luc Roelandt
2014-01-01
Full Text Available Over the past 30 years in the Eastern Lille Public Psychiatric sector, there had been progressive development of set up in community psychiatry. This innovative set up conforms to WHO recommendations. The essential priority is to avoid resorting to traditional hospitalisation, and integrating the entire health system into the city, via a network involving all interested partners: users, carers, families and elected representatives. The ambition of this socially inclusive service is to ensure the adaptation and non-exclusion of persons requiring mental health care and to tackle stigma and discrimination. It gives a new perception to psychiatry that is innovative and experimental, and observing human rights, i.e. citizen psychiatry. This experiment also provides lesson to India for effective implementation of its national mental health program.
8. Lille, de la métropole à la région urbaine
Directory of Open Access Journals (Sweden)
Didier Paris
2002-06-01
Full Text Available Depuis la fin des années 1980, le développement de Lille s'inscrit dans le cadre d'une stratégie de métropolisation. Celle-ci passe notamment par l'aptitude des acteurs politiques et économiques locaux à se mobiliser dans une dynamique de gouvernance et ne peut faire l'impasse sur le grand enjeu d'aménagement et de solidarité que représente la nécessité du renouvellement urbain. Ce processus s'articule à un système régional transfrontalier à forte densité et structuré en réseaux de villes très proches.
9. L’église Saint-Michel de Lille : chronologie d’un chantier
Directory of Open Access Journals (Sweden)
Catherine Guillot
2012-04-01
Full Text Available Après le démantèlement des fortifications de Lille en 1858, un nouveau quartier est aménagé au sud de la ville, dont un des équipements importants est l’église Saint-Michel, construite entre 1868 et 1874 par l’architecte Alfred Coisel. Très bien documenté, son chantier dévoile un mobilier et un décor exemplaire par son homogénéité et par la place accordée à la peinture murale. Cette étude met en évidence, outre le rôle du peintre Alphonse Colas, des artistes méconnus comme Albéric Duyver et Marie Carin. L’iconographie, qui révèle un des plus importants cycles consacrés à l’archange saint Michel, est également extrêmement caractéristique de son temps.After the demolition of the fortifications at Lille, in 1858, a new quarter developed to the south of the city. One of the important features of this new neighbourhood was the Saint-Michel church, built between 1868 and 1874 to the designs of the architect Alfred Coisel. The building of this church is exceptionally well documented and reveals church furnishings and decoration of an exemplary nature in terms of homogeneity and the special place given over to mural paintings. This study underlines the role of the painter Alphonse Colas, but also the contribution of other, less well known artists such as Albéric Duyver and Marie Carin. The iconographical theme is one of the most important cycles of its time devoted to the archangel Saint Michel, and is highly characteristic of the period.
10. Recruitment study nest card
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This is a survey on waterfowl nests in Stillwater Wildlife Management Area. Visits were made to each nest on an approximately weekly basis, and the stage of the eggs...
11. Simulated nest study guide
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — The instructions outlined here will provide uniform methods for measuring total predator activity in blocks of nesting cover or at special kinds of nest sites. The...
12. Columbia River ESI: NESTS (Nest Points)
Data.gov (United States)
National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for bird nesting sites in the Columbia River area. Vector points in this data set represent locations of...
13. PyMultiNest: Python interface for MultiNest
Science.gov (United States)
Buchner, Johannes
2016-06-01
PyMultiNest provides programmatic access to MultiNest (ascl:1109.006) and PyCuba, integration existing Python code (numpy, scipy), and enables writing Prior & LogLikelihood functions in Python. PyMultiNest can plot and visualize MultiNest's progress and allows easy plotting, visualization and summarization of MultiNest results. The plotting can be run on existing MultiNest output, and when not using PyMultiNest for running MultiNest.
14. Kaks kanget: Forgotten Sunrise ning Tharaphitha enne ja nüüd / Anders Melts, Ants Lill ; intervjueerinud Mart Kalvet
Index Scriptorium Estoniae
Melts, Anders
2009-01-01
Küsimustele vastavad dark-elektro-bändi Forgotten Sunrise laulja Anders Melts ja pagan-metal-bändi Tharaphita laulja-kitarrist Ants Lill. Ansamblitest ja nende esimestest heliplaatidest, mis üllitati hiljuti uuesti plaadifirma Nailboard Records poolt: Tharaphita albumi "Raev" digipack-CD, millele on lisatud 1996. aastal ilmunud neljalooline demosalvestis "Kui varjud põlevad" ja Forgotten Sunrise demo "Behind The Abysmal Sky" (1993) ja minialbumi "Forever Sleeping Greystones" (1994) lood
15. Kaks kanget: Forgotten Sunrise ning Tharaphitha enne ja nüüd / Anders Melts, Ants Lill ; intervjueerinud Mart Kalvet
Index Scriptorium Estoniae
Melts, Anders
2009-01-01
Küsimustele vastavad dark-elektro-bändi Forgotten Sunrise laulja Anders Melts ja pagan-metal-bändi Tharaphita laulja-kitarrist Ants Lill. Ansamblitest ja nende esimestest heliplaatidest, mis üllitati hiljuti uuesti plaadifirma Nailboard Records poolt: Tharaphita albumi "Raev" digipack-CD, millele on lisatud 1996. aastal ilmunud neljalooline demosalvestis "Kui varjud põlevad" ja Forgotten Sunrise demo "Behind The Abysmal Sky" (1993) ja minialbumi "Forever Sleeping Greystones" (1994) lood
16. Florence Nightingale som symbolsk overgangsfigur i lærebøger for sygeplejersker - et lille stykke sygeplejehistorie
DEFF Research Database (Denmark)
Jørgensen, Emmy Brandt
2009-01-01
Artiklen er et lille indlæg om, hvordan man har anvendt Florence Nightingale i danske lærebøger for sygeplejersker som en legitimeringsfigur i forbindelse med forandringer inden for det danske hospitalsvæsen. Perioden, der behandles, er tiden før og efter skiftet til den kliniske medicin i Danmar....... Skiftet fra den klassifikatoriske til den kliniske medicin sker i Danmakr i midten af 1800-tallet. Analysen er inspireret af den franske filosof Michel Foucault....
17. Årets gang i ord og sang, med Axel, Anna og lille Camilla
DEFF Research Database (Denmark)
Olesen, Lise Charlotte Sanders; Lefmann, Else
"Årets gang i ord og sang med Axel, Anna og lille Camilla" henvender sig til de 5-8 årige i skole, hjem eller daginstitution - og består af: En illustreret bog med: 14 historier, der følger en familie, bestående af far, mor og tre børn. Gennem et helt år, måned for måned, hører vi om deres liv......, deres oplevelser, glæder og skuffelser. 14 sange, der ligeledes følger familiens liv gennem årstidernes skiften. Til sangene er der såvel noder som becifringer En CD Her er sangene først fuldt arrangeret med musik, børne- og voksenstemmer. Dernæst kommer musikken alene, således at Cd'en også kan bruges...... som akkompagnement, når man synger sangene. Materialet kan bruges på mange måder: Rent pædagogisk kan det bruges til at lære om årets gang og månedernes navne og rækkefølge Som en oplagt mulighed for at lære nye børnevenlige årstids sange i forskellige genre Som samtalestof med gode...
18. Validation of a Spanish Version of the Lille Apathy Rating Scale for Parkinson’s Disease
Directory of Open Access Journals (Sweden)
Rocio García-Ramos
2014-01-01
Full Text Available Introduction. To date, no rating scales for detecting apathy in Parkinson’s disease (PD patients have been validated in Spanish. For this reason, the aim of this study was to validate a Spanish version of Lille apathy rating scale (LARS in a cohort of PD patients from Spain. Participants and Methods. 130 PD patients and 70 healthy controls were recruited to participate in the study. Apathy was measured using the Spanish version of LARS and the neuropsychiatric inventory (NPI. Reliability (internal consistency, test-retest, and interrater reliability and validity (construct, content, and criterion validity were measured. Results. Interrater reliability was 0.93. Cronbach’s α for LARS was 0.81. The test-retest correlation coefficient was 0.97. The correlation between LARS and NPI scores was 0.61. The optimal cutoff point under the ROC curve was -14, whereas the value derived from healthy controls was -11. The prevalence of apathy in our population tested by LARS was 42%. Conclusions. The Spanish version of LARS is a reliable and useful tool for diagnosing apathy in PD patients. Total LARS score is influenced by the presence of depression and cognitive impairment. However, both disorders are independent identities with respect to apathy. The satisfactory reliability and validity of the scale make it an appropriate instrument for screening and diagnosing apathy in clinical practice or for research purposes.
19. [Platelet transfusion and allergic transfusion reactions: experiences at Lille Hospital over a four year period].
Science.gov (United States)
Wibaut, B; Vannier, V; Renom, P; Goudemand, J
2000-04-01
Among the immediate transfusion reactions caused by the utilization of blood products, those suggesting immuno-allergic mechanisms posed problems for frequency, gravity, laboratory diagnosis and safety. We report here the Lille Hospital's experience over a four-year period concerning these manifestations after platelet concentrate transfusion. Eight hundred and fifty-two immediate transfusion reactions have been declared, of which 230 were allergic, which appeared in 181 patients (27%). Among the most frequent clinical signs, rash was often described (158 cases: 68.7%); less frequent were respiratory problems such as dyspnea (34 cases: 14.8%) and hypotensive reactions (18 cases: 7.8%). Seven patients presented severe reactions (3%). Twenty percent of them presented multiple allergic reactions and in 43.2%, the recurrence was more serious than the initial problem in spite of preventive medication; the use of washed blood components was necessary. The age of platelet concentrates does not appear to play a part in provoking these events (67% of platelet concentrates had been collected within four days). These allergic transfusion reactions posed problems for those who prescribe medication, because they are frequent, sometimes serious, can recur and at present, the proposed medication prevention is not always efficient.
20. Morphology of nested fullerenes
Energy Technology Data Exchange (ETDEWEB)
Srolovitz, D.J.; Safran, S.A.; Homyonfer, M.; Tenne, R. (Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100 (Israel))
1995-03-06
We introduce a continuum model which shows that dislocations and/or grain boundaries are intrinsic features of nested fullerenes whose thickness exceeds a critical value to relieve the large inherent strains in these structures. The ratio of the thickness to the radius of the nested fullerenes is determined by the ratio of the surface to curvature and dislocation (or grain boundary) energies. Confirming experimental evidence is presented for nested fullerenes with small thicknesses and with spherosymmetric shapes.
1. Superposition Enhanced Nested Sampling
Directory of Open Access Journals (Sweden)
Stefano Martiniani
2014-08-01
Full Text Available The theoretical analysis of many problems in physics, astronomy, and applied mathematics requires an efficient numerical exploration of multimodal parameter spaces that exhibit broken ergodicity. Monte Carlo methods are widely used to deal with these classes of problems, but such simulations suffer from a ubiquitous sampling problem: The probability of sampling a particular state is proportional to its entropic weight. Devising an algorithm capable of sampling efficiently the full phase space is a long-standing problem. Here, we report a new hybrid method for the exploration of multimodal parameter spaces exhibiting broken ergodicity. Superposition enhanced nested sampling combines the strengths of global optimization with the unbiased or athermal sampling of nested sampling, greatly enhancing its efficiency with no additional parameters. We report extensive tests of this new approach for atomic clusters that are known to have energy landscapes for which conventional sampling schemes suffer from broken ergodicity. We also introduce a novel parallelization algorithm for nested sampling.
2. Multistate nested canalizing functions
CERN Document Server
Adeyeye, J O; Laubenbacher, R; Li, Y
2013-01-01
The concept of a nested canalizing Boolean function has been studied over the course of the last decade in the context of understanding the regulatory logic of molecular interaction networks, such as gene regulatory networks. Such functions appear preferentially in published models of such networks. Recently, this concept has been generalized to include multi-state functions, and a recursive formula has been derived for their number, as a function of the number of variables. This paper carries out a detailed analysis of the class of nested canalizing functions over an arbitrary finite field. Furthermore, the paper generalizes the concept further, and derives a closed formula for the number of such generalized functions. The paper also derives a closed formula for the number of equivalence classes under permutation of variables. This is motivated by the fact that two nested canalizing functions that differ by a permutation of the variables share many important properties with each other. The paper contributes ...
3. Serenbe Nest Cottages
Energy Technology Data Exchange (ETDEWEB)
Butler, T.; Curtis, O.; Kim, E.; Roberts, S.; Stephenson, R.
2012-12-01
As part of the NAHB Research Center Industry Partnership, Southface partnered with Martin Dodson Builders and the Serenbe community on the construction of a new test home in the suburbs of Atlanta, GA in the mixed humid climate zone. The most recent subdivision within the Serenbe community, the Nest, will contain 15 small footprint cottage style homes, and Southface has selected Lot Nine, as the test home for this study. This Nest subdivision serves as a project showcase for both the builder partner and the Serenbe community as a whole. The planning and design incorporated into the Nest cottages will be implemented in each home within the subdivision. These homes addresses Building America Savings targets and serve as a basis of design for other homes Martin Dodson plans to build within the Serenbe community.
4. Late Holocene vegetation and land-use history in Denmark: a multi-decadally resolved record from Lille Vildmose, northeast Jutland
NARCIS (Netherlands)
Yeloff, D.; Broekens, P.M.; Innes, J.; van Geel, B.
2007-01-01
A pollen analysis of a peat profile collected from Lille Vildmose, Denmark has been used to reconstruct vegetation and land-use change from the late Iron Age (ca. 690 cal. AD) to the present day. ‘Wiggle-matching’ of 34 AMS 14C dates has enabled a precise (decadal scale) chronology to be
5. Late Holocene vegetation and land-use history in Denmark: a multi-decadally resolved record from Lille Vildmose, northeast Jutland
NARCIS (Netherlands)
Yeloff, D.; Broekens, P.M.; Innes, J.; van Geel, B.
2007-01-01
A pollen analysis of a peat profile collected from Lille Vildmose, Denmark has been used to reconstruct vegetation and land-use change from the late Iron Age (ca. 690 cal. AD) to the present day. ‘Wiggle-matching’ of 34 AMS 14C dates has enabled a precise (decadal scale) chronology to be established
6. La couleur à Lille au xviie siècle, de Philippe IV à Louis XIV The colour of Lille in the seventeenth century, from Philippe IV to Louis XIV
Directory of Open Access Journals (Sweden)
Étienne Poncelet
2007-06-01
Full Text Available Pays polychrome, de pierres blanches ou bleues et de briques roses, jaunes ou noires, la Flandre manie depuis le Moyen Âge les jeux colorés de matériaux. Sa capitale wallonne, Lille, est la ville méridionale des Pays‑Bas catholiques où s’acclimatent les plantes de la compagnie des Indes néerlandaises et où se déroulent les « joyeuses entrées » des comtes, ducs de Bourgogne, archiducs et autres rois d’Espagne. Cette tradition de luxuriance se traduit à l’âge d'or bourguignon par une efflorescence de couleurs sur les édifices qui durera jusqu’à la prise de Lille par Louis XIV en 1667. Les portes « espagnoles » affichent leurs briques émaillées de couleur. L’hospice Comtesse placarde son retable de pierres peintes sur sa façade d’entrée. La Vieille Bourse colore ses façades au modèle d’un cabinet d’ébénisterie avec ses incrustations de pierres nacrées et de brique luisantes comme les écailles de tortue. Le style franco‑lillois transmettra ce goût pour la couleur à travers la reconstitution du centre ville au xviie siècle, ce dont témoigne le plan-relief de 1743. Les restaurations depuis une dizaine d’années retrouvent cette tradition de joie urbaine dans les autres « grand-places » des villes du Nord.A polychromatic land of white and blue stone and pink, yellow and black brick, Flanders has sought colour combinations in building materials since the Middle Ages. Its French-speaking capital, Lille, was the city in the south of the Catholic Netherlands where plants imported by the Dutch East Indies Company acclimatized and where the ‘Joyous Entry’ celebrations of the counts, Dukes of Burgundy, archdukes and kings of Spain took place. During the golden age of Burgundy, this tradition of luxuriance was reflected in the increasing use of colours on buildings, a trend that would endure until the siege of Lille by Louis XIV in 1667. The ‘Spanish’ gates display brickwork enamelled in
7. Density-dependent nest predation in waterfowl: the relative importance of nest density versus nest dispersion
Science.gov (United States)
Ackerman, Joshua T.; Ringelman, Kevin M.; Eadie, J.M.
2012-01-01
When nest predation levels are very high or very low, the absolute range of observable nest success is constrained (a floor/ceiling effect), and it may be more difficult to detect density-dependent nest predation. Density-dependent nest predation may be more detectable in years with moderate predation rates, simply because there can be a greater absolute difference in nest success between sites. To test this, we replicated a predation experiment 10 years after the original study, using both natural and artificial nests, comparing a year when overall rates of nest predation were high (2000) to a year with moderate nest predation (2010). We found no evidence for density-dependent predation on artificial nests in either year, indicating that nest predation is not density-dependent at the spatial scale of our experimental replicates (1-ha patches). Using nearest-neighbor distances as a measure of nest dispersion, we also found little evidence for “dispersion-dependent” predation on artificial nests. However, when we tested for dispersion-dependent predation using natural nests, we found that nest survival increased with shorter nearest-neighbor distances, and that neighboring nests were more likely to share the same nest fate than non-adjacent nests. Thus, at small spatial scales, density-dependence appears to operate in the opposite direction as predicted: closer nearest neighbors are more likely to be successful. We suggest that local nest dispersion, rather than larger-scale measures of nest density per se, may play a more important role in density-dependent nest predation.
Science.gov (United States)
Nabors, Martha L.; Edwards, Linda Carol; Decker, Suzanne
2010-01-01
The first-grade classroom was like a natural history museum. Bird nests of every shape and size lay on top of bookshelves that lined two walls. Methods students, who were visiting the classroom in preparation for the science lessons they would teach there, were immediately inspired by the collection. They used the collection as a springboard for…
9. Simulated nests in wildlife management
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Many of us have studied game bird nests. Usually we hoped to learn something about nesting cover, cover management and the birds and animals which seemed to eat the...
10. Nest and nest site characterisitcs of some ground-nesting, non-passerine birds of northern grasslands
Science.gov (United States)
Kantrud, H.A.; Higgins, K.F.
1992-01-01
We summarized biological and ecologic characteristics of 2490 nests of 16 species of upland-nesting, non-passerine birds of northern grasslands found during 1963 through 1991. Nest initiation and hatch dates, clutch sizes, nest fates, causes of failure, success rates of nests among major habitat types and land uses, and vegetation measurements at nest sites are analyzed.
11. Muusikamaailm : Telemanni festival Magdeburgis. Suurkontsert Lille'is. Straussi ooperi tähtpäev. Kahelt konkursilt. Viini festival tuleb põnev / Priit Kuusk
Index Scriptorium Estoniae
Kuusk, Priit, 1938-
2000-01-01
Märtsis 2000. a. toimuvast Telemanni festivalist Magdeburgis Saksamaal. Lille"is Prantsusmaal toimunud kontserdist, kus oli ettekandel D. Milhaud" muusika P. Claudeli näidendile "Les Choephores". R. Straussi ooperi "Naine ilma varjuta" uuslavastusest Viini Riigiooperis. Prantsusmaal Besanconis toimunud 46. rahvusvahelisest noorte dirigentide konkursist, 4. H. Dutilleux" nimelisest noorte heliloojate konkursist Pariisis. 14. mail. 2000 avatavatest Viini pidunädalatest (Wiener Festwochen)
12. Intelligent nesting system
Directory of Open Access Journals (Sweden)
Đuričić Zoran
2003-01-01
Full Text Available The economy of the process for the manufacture of parts from sheet metal plates depends on successful solution of the process of cutting various parts from sheet metal plates. Essentially, the problem is to arrange contours within a defined space so that they take up minimal surface. When taken in this way, the considered problem assumes a more general nature; it refers to the utilization of a flat surface, and it can represent a general principle of arranging 2D contours on a certain surface. The paper presents a conceptual solution and a prototypal intelligent nesting system for optimal cutting. The problem of nesting can generally be divided into two intellectual phases: recognition and classification of shapes, and arrangement of recognized shapes on a given surface. In solving these problems, methods of artificial intelligence are applied. In the paper, trained neural network is used for recognition of shapes; on the basis of raster record of a part's drawing, it recognizes the part's shape and which class it belongs to. By means of the expert system, based on rules defined on the basis of acquisition of knowledge from manufacturing sections, as well as on the basis of certain mathematical algorithms, parts are arranged on the arrangement surface. Both systems can also work independently, having been built on the modular principle. The system uses various product models as elements of integration for the entire system. .
13. 2004欧洲文化之都:创意城市里尔%European Capital of Culture in 2004: Creative Lille
Institute of Scientific and Technical Information of China (English)
罗朗·德雷阿诺; 让·玛利·埃尔耐克; 赵淑美
2012-01-01
文章概述了法国里尔从举办欧洲文化之都“里尔2004”盛会开始,通过各种文化创意途径促进城市经济发展、提升城市声望、实现城市转型的种种经验.文化不仅让公众分享到了更加美好的城市生活,更为里尔在国际领域的迅猛发展创造了机会.%the paper briefly introduces how Lille began to conduct "Lille 2004" , a mega event of being European capital of culture, and its experiences of promoting urban economic development, enhancing the city' s prestige and realizing urban transformation through various creative cultural approaches. Culture itself not only allows the public to share the better urban life, but also creates opportunities for Lille to develop rapidly in the global arena.
14. PyNEST: a convenient interface to the NEST simulator
Directory of Open Access Journals (Sweden)
Jochen M Eppler
2009-01-01
Full Text Available The neural simulation tool NEST (http://www.nest-initiative.org is a simulator for heterogeneous networks of point neurons or neurons with a small number of compartments. It aims at simulations of large neural systems with more than 10^4 neurons and 10^7 to 10^9 synapses. NEST is implemented in C++ and can be used on a large range of architectures from single-core laptops over multi-core desktop computers to super-computers with thousands of processor cores. Python (http://www.python.org is a modern programming language that has recently received considerable attention in Computational Neuroscience. Python is easy to learn and has many extension modules for scientific computing (e.g. http://www.scipy.org. In this contribution we describe PyNEST, the new user interface to NEST. PyNEST combines NEST’s efficient simulation kernel with the simplicity and flexibility of Python. Compared to NEST’s native simulation language SLI, PyNEST makes it easier to set up simulations, generate stimuli, and analyze simulation results. We describe how PyNEST connects NEST and Python and how it is implemented. With a number of examples, we illustrate how it is used.
15. El papel de las redes sociales en la actividad económica: el caso de los restauradores de Lille.
Directory of Open Access Journals (Sweden)
Elorie, Fabien
2009-06-01
Full Text Available This article is rooted in two fields of research: economic sociology and network analysis. The network approach we develop here is not an ego-network approach based on the individual level of analysis, but is a socio-centric approach based on the meso-social level of analysis. We focus our attention on the objective structures that govern markets. We rely on the empirical case of three hundred restaurants’ owners situated in the area of Lille in the North of France. Our population reconstitutes an inter-organisational complete network. First, we explain how we have empirically constructed this population. Second, we present this restaurant industry, on the one hand as an interface of production (White and, on the other hand as a field (Bourdieu. Third, we show how these economic and social structures are connected with the relational structure. In our view, the relational structure relates to a social exchange system of social resources (Lazega. Finally, our approach suggests a heterodox conception of how is running a market.
16. [Management of aspergillosis in immunocompromised patients. Recommendations of Lille University Hospital--4th version--November 2004].
Science.gov (United States)
Alfandari, S; Leroy, O; de Botton, S; Yakoub-Agha, I; Durand-Joly, I; Leroy-Cotteau, A; Beaucaire, G
2005-03-01
Invasive aspergillosis is a severe complication in immunocompromised patients. The arrival of new antifungal agents motivated the redaction of guidelines, regularly updated, by a Lille University hospital multidisciplinary task force. These guidelines assess diagnostic and therapeutic issues. The main recommended diagnosis tool is the chest CT scan, ordered at the smallest suspicion and, also, measure of the blood and broncho alveolar lavage fluid galactomannan. Treatment guidelines assess prophylaxis, empirical and documented therapy. Primary prophylaxis is warranted in only two cases, pulmonary graft or stem cell transplant in patients with chronic GVH and receiving corticosteroids. Empirical therapy should use one of the available amphotericin B formulations, chosen according to the patient history. Caspofungin is another choice. Documented therapy, depending on presentation, can be a single drug or a combination. First line therapy for single drug is i.v. voriconazole. Lipid formulations of amphotericin B are another choice. A combination therapy can be used as a first line treatment, for multiple lesions, or as salvage therapy. It must include caspofungin, associated with liposomal amphotericin B or voriconazole. A tight cooperation with thoracic surgeons is recommended.
17. The Nest Home
Energy Technology Data Exchange (ETDEWEB)
Pickerill, Heath [Missouri Univ. of Science and Technology, Rolla, MO (United States)
2016-07-11
The purpose of the project was to build a competitive solar-powered house for the U.S. Department of Energy Solar Decathlon 2015 held in Irvine, California. The house, named the Nest Home, was an innovative design that works with the environment to meet the needs of the occupants, identified as a growing family. Reused materials were instrumental in the design. Three refurbished shipping containers composed the primary structure of the house, creating an open floor plan that defies common architecture for container homes. The exterior siding was made of deconstructed shipping pallets collected locally. Other recycled products included carpet composed of discarded fishing nets, denim batting made of recycled blue jeans that outperform traditional fiberglass insulation in sound proofing and thermal resistance, and kitchen cabinets that were purchased used and refinished. Collectively these elements formed a well-balanced blend of modern design, comfort, and sustainability. The house was Missouri University of Science and Technology’s sixth entry in the DOE Solar Decathlon. Missouri S&T has been invited to compete in six of the seven decathlons held, more than any other university worldwide. The house was brought back to Rolla after the Decathlon in California where it has been placed in its permanent location on the S&T campus.
18. Nested subgraphs of complex networks
Energy Technology Data Exchange (ETDEWEB)
Corominas-Murtra, Bernat; Sole, Ricard V [ICREA-Complex Systems Lab, Universitat Pompeu Fabra, Dr Aiguader 80, 08003 Barcelona (Spain); Mendes, Jose F F [Departamento de Fisica da Universidade de Aveiro, 3810-193 Aveiro (Portugal)], E-mail: [email protected]
2008-09-26
We analytically explore the scaling properties of a general class of nested subgraphs in complex networks, which includes the K-core and the K-scaffold, among others. We name such a class of subgraphs K-nested subgraphs since they generate families of subgraphs such that ...S{sub K+1}(G) subset or equal S{sub K}(G) subset or equal S{sub K-1}(G).... Using the so-called configuration model it is shown that any family of nested subgraphs over a network with diverging second moment and finite first moment has infinite elements (i.e. lacking a percolation threshold). Moreover, for a scale-free network with the above properties, we show that any nested family of subgraphs is self-similar by looking at the degree distribution. Both numerical simulations and real data are analyzed and display good agreement with our theoretical predictions.
19. Factors influencing depredation of artificial duck nests
Science.gov (United States)
Esler, Daniel N.; Grand, James B.
1993-01-01
Because artificial nests can facilitate controlled experiments of nest success, we used them to assess whether human visitation, nest density, vegetation structure, and proximity to habitat edge could affect depredation of duck nests on Yukon Flats National Wildlife Refuge, Alaska. More (P depredated than those in plots visited at intervals of 7 (40%), 14 (35%), or 28 days (45%). More (P depredated in a plot with 10 nests/ha (95%) than nests in a plot of a lower density (2/ha; 40%). Vegetation height, vegetation density, distance to a wetland, distance to forest edge, or distance to the nearest ecotone did not differ (P > 0.05) between depredated and undisturbed nests. We suggest that daily visitation of duck nests increases depredation, but longer intervals, typical of most nest studies, do not. High nesting densities, which could occur when flooding limits nesting habitat, may result in higher depredation rates.
20. Nest poaching in Neotropical parrots
Science.gov (United States)
Wright, T.F.; Toft, C.A.; Enkerlin-Hoeflich, E.; Gonzalez-Elizondo, J.; Albornoz, M.; Rodriguez-Ferraro, A.; Rojas-Suarez, F.; Sanz, V.; Trujillo, A.; Beissinger, S.R.; Berovides A., V.; Galvez A., X.; Brice, A.T.; Joyner, K.; Eberhard, J.; Gilardi, J.; Koenig, S.E.; Stoleson, S.; Martuscelli, P.; Meyers, J.M.; Renton, K.; Rodriguez, A.M.; Sosa-Asanza, A.C.; Vilella, F.J.; Wiley, J.W.
2001-01-01
Although the poaching of nestlings for the pet trade is thought to contribute to the decline of many species of parrots, its effects have been poorly demonstrated. We calculated rates of mortality due to nest poaching in 23 studies of Neotropical parrots, representing 4024 nesting attempts in 21 species and 14 countries. We also examined how poaching rates vary with geographic region, presence of active protection programs, conservation status and economic value of a species, and passage of the U.S. Wild Bird Conservation Act. The average poaching rate across all studies was 30% of all nests observed. Thirteen studies reported poaching rates of >20%, and four reported rates of >70%. Only six studies documented no nest poaching. Of these, four were conducted on islands in the Caribbean region, which had significantly lower poaching rates than the mainland Neotropics. The other two studies that showed no poaching were conducted on the two species with the lowest economic value in our sample (U.S. retail price). In four studies that allowed direct comparison between poaching at sites with active nest protection versus that at unprotected sites, poaching rates were significantly lower at protected sites, suggesting that active protection efforts can be effective in reducing nest poaching. In those studies conducted both before and after the passage of the U.S. Wild Bird Conservation Act, poaching rates were found to be significantly lower following its enactment than in the period before. This result supports the hypothesis that the legal and illegal parrot trades are positively related, rather than inversely related as has been suggested by avicultural interests. Overall, our study indicates that poaching of parrot nestlings for economic gain is a widespread and biologically significant source of nest mortality in Neotropical parrots.
1. Successful nesting behavior of Puerto Rican parrots
Science.gov (United States)
Wilson, K.A.; Field, R.; Wilson, M.H.
1995-01-01
We analyzed nesting behavior of five pairs of the endangered Puerto Rican Parrot (Amazona vittata) during eight successful nesting attempts. Each stage of the nesting cycle (egg laying, incubation, early chick rearing, and late chick rearing) was characterized by distinct trends or levels of behavior. During egg laying, female attentiveness to tile nest increased, and male attentiveness decreased. Throughout incubation and the first several days of early chick rearing, females were highly attentive to their nests, whereas males rarely entered the nest cavities. Female attentiveness then began to decline. Male attentiveness to the nest was sporadic until chicks were 10-12 days old. when all males began to enter their nests at least once each day. During late chick rearing, both male and female attentiveness were erratic and highly variable. Biologists may be able to use these results to identify nest problems and the need for management intervention when patterns of nest attentiveness deviate from the limits described in this study..
2. Lille mand, stor kanon
DEFF Research Database (Denmark)
Bengtsson, Mette
2011-01-01
I fredagens første valgduel på TV2 kører Løkke effektivt frem med en ordentlig kanon af en elefantbøsse, men skrider i svinget med sine fortielser og fordrejninger. Thorning møder velforberedt op med relevante fakta og konkrete eksempler, men forfalder til intern socialdemokrat-lingo. Kort sagt...
3. Den lille galskab
DEFF Research Database (Denmark)
Gitz-Johansen, Thomas
2016-01-01
The article discusses symbolization as a specific psychological method informed by psychodynamic theory. The point of departure is taken in a critique of modern society as disenchanted in the sense that a one-sided appreciation of reason has displaced and delegitimized irrational modes....... Finally, the article discusses practices of symbolization in a broader cultural context....
4. EU's lille sikkerhedsnet
DEFF Research Database (Denmark)
Rangvid, Jesper
2014-01-01
I forrige uge indgik EU-kommissionen og EU-Parlamentet en aftale om en fælles afviklingsmekanisme i bank-unionen (Single Resolution Mechanism; SRM). ... Så på trods af mere kapital, nye bail-in regler og afviklingsfonden tror jeg ikke, at det kan udelukkes, at fremtidige "bankredninger" kan nødve...... nødvendigøre statslige midler. Hertil er fonden trods alt for begrænset. ... Proceduren er, at ECB indstiller til SRM's bestyrelse, at en bank skal afvikles, hvorefter EU-kommissionen og nationale tilsynsmyndigheder involveres....
5. Pensionilepe Venemaaga / Eli Lilles
Index Scriptorium Estoniae
Lilles, Eli
2007-01-01
16. oktoobril 2007 jõustunud Eesti ja Venemaa vahelisest pensionilepingust, mis puudutab Eestis elavaid Vene kodanikest pensionäre, kes 1991. aastani töötasid mujal NSV Liidus ja Venemaal ning kelle tööstaaži siiani Eestis arvesse ei võetud
6. EU's lille sikkerhedsnet
DEFF Research Database (Denmark)
Rangvid, Jesper
2014-01-01
I forrige uge indgik EU-kommissionen og EU-Parlamentet en aftale om en fælles afviklingsmekanisme i bank-unionen (Single Resolution Mechanism; SRM). ... Så på trods af mere kapital, nye bail-in regler og afviklingsfonden tror jeg ikke, at det kan udelukkes, at fremtidige "bankredninger" kan...
7. Pensionilepe Venemaaga / Eli Lilles
Index Scriptorium Estoniae
Lilles, Eli
2007-01-01
16. oktoobril 2007 jõustunud Eesti ja Venemaa vahelisest pensionilepingust, mis puudutab Eestis elavaid Vene kodanikest pensionäre, kes 1991. aastani töötasid mujal NSV Liidus ja Venemaal ning kelle tööstaaži siiani Eestis arvesse ei võetud
8. Can selection on nest size from nest predation explain the latitudinal gradient in clutch size?
Science.gov (United States)
Biancucci, L.; Martin, T.E.
2010-01-01
1. Latitudinal variation in clutch sizes of birds is a well described, but poorly understood pattern. Many hypotheses have been proposed, but few have been experimentally tested, and none have been universally accepted by researchers. 2. The nest size hypothesis posits that higher nest predation in the tropics favours selection for smaller nests and thereby constrains clutch size by shrinking available space for eggs and/or nestlings in the nest. We tested this hypothesis with an experiment in a tropical forest and a comparative study between temperate and tropical field sites. 3. Specifically, we tested if: (i) predation increased with nest size; (ii) tropical birds had smaller nests controlled for body size; and (iii) clutch size was explained by nest size controlled for body size. 4. Experimental swapping of nests of different sizes showed that nest predation increased with nest size in the tropical site. Moreover, nest predation rates were higher in species with larger nests in both sites. However, nest size, corrected for body mass and phylogeny, did not differ between sites and was not related to clutch size between sites. 5. Hence, nest predation can exert selection on nest size as predicted by the hypothesis. Nest size increased with adult body mass, such that adult size might indirectly influence reproductive success through effects on nest size and nest predation risk. Ultimately, however, selection from nest predation on nest size does not explain the smaller clutch sizes typical of the tropics.
9. Nested Dynamic Condition Response Graphs
DEFF Research Database (Denmark)
Hildebrandt, Thomas; Mukkamala, Raghava Rao; Slaats, Tijs
2012-01-01
We present an extension of the recently introduced declarative process model Dynamic Condition Response Graphs ( DCR Graphs) to allow nested subgraphs and a new milestone relation between events. The extension was developed during a case study carried out jointly with our industrial partner...... Exformatics, a danish provider of case and workflow management systems. We formalize the semantics by giving first a map from Nested to (flat) DCR Graphs with milestones, and then extending the previously given mapping from DCR Graphs to Buchi-automata to include the milestone relation....
10. Patterns of magpie nest utilization by a nesting raptor community in a secondary forest
Institute of Scientific and Technical Information of China (English)
Tong Zhou; Haitao Wang; Yu Liu; Fumin Lei; Wei Gao
2009-01-01
For a total of 9 years, we examined the patterns of a nesting raptor community that utilized European Magpie (Pica pica) nests in the Zuojia Natural Reserve, northeast China. Eight raptor species and two other bird species were recorded nesting in magpie nests. The reuse rate of abandoned magpie nests was 51.6%, and the number of reused nests was positively correlated with their availability. Raptors utilized 83.3% of the reused abandoned magpie nests. Nests followed for more than 1 year were reused by raptors an average of 1.13 times. Inter-specific nest usurpation was common, with 17.3% of new magpie nests being usurped by raptors, and four cases of usurpation occurred among different raptor species. At the community level, 8 of 11 raptor species took over magpie nests to breed in the study area, and 91.9% of their nests came from magpie nests. European Magpies represent the core species in the nest web of the local raptor community that utilizes magpie nests. At the forest stand level, closer proximity to forest edges and greater distances from occupied raptor nests were the best predictors of nest reuse. At the nest-site level, arbor density and canopy coverage were the best predictors of nest reuse.
11. Unusual raptor nests around the world
Science.gov (United States)
Ellis, D.H.; Craig, T.; Craig, E.; Postupalsky, S.; LaRue, C.T.; Nelson, R.W.; Anderson, D.W.; Henny, C.J.; Watson, J.; Millsap, B.A.; Dawson, J.W.; Cole, K.L.; Martin, E.M.; Margalida, A.; Kung, P.
2009-01-01
From surveys in many countries, we report raptors using unusual nesting materials (e.g., paper money, rags, metal, antlers, and large bones) and unusual nesting situations. For example, we documented nests of Steppe Eagles Aquila nipalensis and Upland Buzzards Buteo hemilasius on the ground beside well-traveled roads, Saker Falcon Falco cherrug eyries in attics and a cistern, and Osprey Pandion haliaetus nests on the masts of boats and on a suspended automobile. Other records include a Golden Eagle A. chrysaetos nest 7.0 m in height, believed to be the tallest nest ever described, and, for the same species, we report nesting in rudimentary nests. Some nest sites are within a few meters of known predators or competitors. These unusual observations may be important in revealing the plasticity of a species' behavioral repertoire. ?? 2009 The Raptor Research Foundation, Inc.
12. Instantiation Schemes for Nested Theories
CERN Document Server
Echenim, Mnacho
2011-01-01
This paper investigates under which conditions instantiation-based proof procedures can be combined in a nested way, in order to mechanically construct new instantiation procedures for richer theories. Interesting applications in the field of verification are emphasized, particularly for handling extensions of the theory of arrays.
13. Development with age of nest box use and gregarious nesting in laying hens
DEFF Research Database (Denmark)
Riber, Anja Brinch
2010-01-01
Use of nest boxes is an important part of the behavioural repertoire of laying hens kept under commercial conditions. A special form of nest box use is gregarious nesting, which occurs when a hen given the choice between an occupied and an unoccupied nest site chooses the occupied nest site...... experiences in selection of nest locations, causing the found decrease in frequency of gregarious nesting after age 20 weeks. A general preference for corner and end nest boxes is suggested to have triggered the initial use of the left nest box by the first hens coming into lay and to have maintained...... risk of broken or dirty eggs. The main objectives were to investigate the use of nest boxes according to their position and the occurrence of gregarious nesting with age. Twelve groups of 15 Isa Warren hens were housed in pens each containing three adjacent roll-out nest boxes only differing...
14. Influence of Habitat Types on Prairie Nesting Waterfowl Nest Density and Nest Success in Northeastern North Dakota, 2010 – 2013
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Nest density and nest success of ducks in native and non-native grasslands within the Devils Lake WMD, Northeastern North Dakota. Waterfowl representing 8 species of...
15. Importance Nested Sampling and the MultiNest Algorithm
CERN Document Server
Feroz, F; Cameron, E; Pettitt, A N
2013-01-01
Bayesian inference involves two main computational challenges. First, in estimating the parameters of some model for the data, the posterior distribution may well be highly multi-modal: a regime in which the convergence to stationarity of traditional Markov Chain Monte Carlo (MCMC) techniques becomes incredibly slow. Second, in selecting between a set of competing models the necessary estimation of the Bayesian evidence for each is, by definition, a (possibly high-dimensional) integration over the entire parameter space; again this can be a daunting computational task, although new Monte Carlo (MC) integration algorithms offer solutions of ever increasing efficiency. Nested sampling (NS) is one such contemporary MC strategy targeted at calculation of the Bayesian evidence, but which also enables posterior inference as a by-product, thereby allowing simultaneous parameter estimation and model selection. The widely-used MultiNest algorithm presents a particularly efficient implementation of the NS technique for...
16. Valorização de bairros antigos e ressignificação da alteridade: o exemplo de Wazemmes em Lille
Directory of Open Access Journals (Sweden)
Abdelhafid Hammouche
2013-06-01
Full Text Available Este artigo examina a dinâmica urbana em bairros submetidos à gentrificação, mais precisamente aquela de Wazemmes, bairro perto do centro da cidade de Lille, no Norte da Franca. Em Wazemmes ocorreram mudanças sensíveis nas ultimas décadas. O bairro tornou-se um espaço cosmopolita, onde convive uma população de grande diversidade. Conta com uma ação publica em domínios variados, sobretudo nos registros social e cultural. De um espaço difamado em razão da delinquência, e do medo por causa da forte presença de imigrantes, e agora valorizado, tornando-se um lugar emblemático quanto a sua urbanidade e sua etnicidade.
17. Ouray National Wildlife Refuge : Duck nesting survey
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Summary report of the 1991 duck nest survey at Ouray National Wildlife Refuge. Key areas of the refuge were nest searched during the period between May 25th and July...
18. Sorting it out: bedding particle size and nesting material processing method affect nest complexity.
Science.gov (United States)
Robinson-Junker, Amy; Morin, Amelia; Pritchett-Corning, Kathleen; Gaskill, Brianna N
2017-04-01
As part of routine husbandry, an increasing number of laboratory mice receive nesting material in addition to standard bedding material in their cages. Nesting material improves health outcomes and physiological performance in mice that receive it. Providing usable nesting material uniformly and efficiently to various strains of mice remains a challenge. The aim of this study was to determine how bedding particle size, method of nesting material delivery, and processing of the nesting material before delivery affected nest building in mice of strong (BALB/cAnNCrl) and weak (C3H/HeNCrl) gathering abilities. Our data suggest that processing nesting material through a grinder in conjunction with bedding material, although convenient for provision of bedding with nesting material 'built-in', negatively affects the integrity of the nesting material and subsequent nest-building outcomes. We also found that C3H mice, previously thought to be poor nest builders, built similarly scored nests to those of BALB/c mice when provided with unprocessed nesting material. This was true even when nesting material was mixed into the bedding substrate. We also observed that when nesting material was mixed into the bedding substrate, mice of both strains would sort their bedding by particle size more often than if it were not mixed in. Our findings support the utility of the practice of distributing nesting material mixed in with bedding substrate, but not that of processing the nesting material with the bedding in order to mix them.
19. Nested Quantum Error Correction Codes
CERN Document Server
Wang, Zhuo; Fan, Hen; Vedral, Vlatko
2009-01-01
The theory of quantum error correction was established more than a decade ago as the primary tool for fighting decoherence in quantum information processing. Although great progress has already been made in this field, limited methods are available in constructing new quantum error correction codes from old codes. Here we exhibit a simple and general method to construct new quantum error correction codes by nesting certain quantum codes together. The problem of finding long quantum error correction codes is reduced to that of searching several short length quantum codes with certain properties. Our method works for all length and all distance codes, and is quite efficient to construct optimal or near optimal codes. Two main known methods in constructing new codes from old codes in quantum error-correction theory, the concatenating and pasting, can be understood in the framework of nested quantum error correction codes.
20. An Undecidable Nested Recurrence Relation
CERN Document Server
Celaya, Marcel
2012-01-01
Roughly speaking, a recurrence relation is nested if it contains a subexpression of the form ... A(...A(...)...). Many nested recurrence relations occur in the literature, and determining their behavior seems to be quite difficult and highly dependent on their initial conditions. A nested recurrence relation A(n) is said to be undecidable if the following problem is undecidable: given a finite set of initial conditions for A(n), is the recurrence relation calculable? Here calculable means that for every n >= 0, either A(n) is an initial condition or the calculation of A(n) involves only invocations of A on arguments in {0,1,...,n-1}. We show that the recurrence relation A(n) = A(n-4-A(A(n-4)))+4A(A(n-4)) +A(2A(n-4-A(n-2))+A(n-2)). is undecidable by showing how it can be used, together with carefully chosen initial conditions, to simulate Post 2-tag systems, a known Turing complete problem.
1. Supramolecular nesting of cyclic polymers.
Science.gov (United States)
Kondratuk, Dmitry V; Perdigão, Luís M A; Esmail, Ayad M S; O'Shea, James N; Beton, Peter H; Anderson, Harry L
2015-04-01
Advances in template-directed synthesis make it possible to create artificial molecules with protein-like dimensions, directly from simple components. These synthetic macromolecules have a proclivity for self-organization that is reminiscent of biopolymers. Here, we report the synthesis of monodisperse cyclic porphyrin polymers, with diameters of up to 21 nm (750 C–C bonds). The ratio of the intrinsic viscosities for cyclic and linear topologies is 0.72, indicating that these polymers behave as almost ideal flexible chains in solution. When deposited on gold surfaces, the cyclic polymers display a new mode of two-dimensional supramolecular organization, combining encapsulation and nesting; one nanoring adopts a near-circular conformation, thus allowing a second nanoring to be captured within its perimeter, in a tightly folded conformation. Scanning tunnelling microscopy reveals that nesting occurs in combination with stacking when nanorings are deposited under vacuum, whereas when they are deposited directly from solution under ambient conditions there is stacking or nesting, but not a combination of both.
2. Nesting behavior of the poo-uli
Science.gov (United States)
Kepler, C.B.; Pratt, T.K.; Ecton, A.M.; Engilis, A.; Fluetsch, K.M.
1996-01-01
We describe two sequential nestings of a pair of Poo-uli (Melamprosops phaeosoma), a Hawaiian honeycreeper nearing extinction. Similarities to nesting of most other honeycreepers included: nest site in ohia lehua (Metrosideros polymorpha Gaud.) canopy; breeding in March through June; monogamous breeding system with the putative male helping build the nest, feeding the putative female throughout each nesting event, and feeding the chicks, but not incubating or brooding; and complete nest sanitation. Notable differences were the paucity of songs and calls by the parents and inclusion of snails in the diet of nestlings. Clutch size was probably two eggs for both nests. High winds, rain, or both influenced parental behavior: the female stayed longer on the nest and took shorter recesses in poor weather. Weather did not affect rates at which the male fed the female on the nest; however, the feeding rate increased from the egg to the chick stage probably because food was passed on to the chicks. At nest #2, parents fed young chicks (<14 days old) more often in good than in poor weather; data were insufficient for old chicks. Weather is usually poor throughout the year in the relictual range of the Poo-uli and is likely to impact nesting success. The first nest failed in poor weather. The second fledged a single young 21 days old. Diet of nestlings appeared to consist of a higher proportion of insect larvae than that of older birds, which are reported to eat mostly snails.
3. On the Denesting of Nested Square Roots
Science.gov (United States)
Gkioulekas, Eleftherios
2017-01-01
We present the basic theory of denesting nested square roots, from an elementary point of view, suitable for lower level coursework. Necessary and sufficient conditions are given for direct denesting, where the nested expression is rewritten as a sum of square roots of rational numbers, and for indirect denesting, where the nested expression is…
4. A démarche estratégica: a metodologia de gestão do Centro Hospitalar Regional Universitário de Lille, França The strategic management: the methodology applied by the "Centre Hospitalier Regional Universitaire"(CHRU at Lille, France
Directory of Open Access Journals (Sweden)
Francisco Javier Uribe Rivera
1997-01-01
Full Text Available Este trabalho é uma apresentação geral do enfoque da "démarche" estratégica (o processo estratégico, aplicado pelo Centro Hospitalar Regional Universitário (CHRU de Lille, França. Este é um método de gestão hospitalar, baseado na análise estratégica das melhores alternativas de racionalização da missão hospitalar. Considera um ambiente de competição, onde é necessário estruturar redes de cuidados com base na negociação dos projetos de estabelecimento. O autor apresenta as fases e os principais instrumentos metodológicos do enfoque e faz uma avaliação preliminar de possibilidades.This work is a general presentation of the "Démarche Stratégique", a strategic process applied by the "Centre Hospitalier Régional Universitaire" (CHRU at Lille, France. The hospital management methodology relies on the strategic analysis of the best alternatives for rationalizing the hospital mission. It takes into account a competitive environment, in which it is necessary to structure health care networks based on the negotiation of inpatient care goals. The author presents the phases and main methodological tools of the approach, as well as a preliminary evaluation of its potentials.
5. Nest Material Shapes Eggs Bacterial Environment.
Directory of Open Access Journals (Sweden)
Cristina Ruiz-Castellano
Full Text Available Selective pressures imposed by pathogenic microorganisms to embryos have selected in hosts for a battery of antimicrobial lines of defenses that includes physical and chemical barriers. Due to the antimicrobial properties of volatile compounds of green plants and of chemicals of feather degrading bacteria, the use of aromatic plants and feathers for nest building has been suggested as one of these barriers. However, experimental evidence suggesting such effects is scarce in the literature. During two consecutive years, we explored experimentally the effects of these nest materials on loads of different groups of bacteria (mesophilic bacteria, Enterobacteriaceae, Staphylococcus and Enterococcus of eggshells in nests of spotless starlings (Sturnus unicolor at the beginning and at the end of the incubation period. This was also explored in artificial nests without incubation activity. We also experimentally increased bacterial density of eggs in natural and artificial nests and explored the effects of nest lining treatments on eggshell bacterial load. Support for the hypothetical antimicrobial function of nest materials was mainly detected for the year and location with larger average values of eggshell bacterial density. The beneficial effects of feathers and plants were more easily detected in artificial nests with no incubation activity, suggesting an active role of incubation against bacterial colonization of eggshells. Pigmented and unpigmented feathers reduced eggshell bacterial load in starling nests and artificial nest boxes. Results from artificial nests allowed us to discuss and discard alternative scenarios explaining the detected association, particularly those related to the possible sexual role of feathers and aromatic plants in starling nests. All these results considered together confirm the antimicrobial functionality mainly of feathers but also of plants used as nest materials, and highlight the importance of temporally and
6. Effect of heterogeneity of nest boxes on occurrence of gregarious nesting in laying hens
DEFF Research Database (Denmark)
Clausen, Tina; Riber, Anja Brinch
2012-01-01
Gregarious nesting, where hens select already occupied nest boxes even when other nest boxes are unoccupied, is an unwanted behaviour in laying hens that may reduce animal welfare and pose a financial cost to the producer. It has been suggested that gregarious nesting is caused by the difficulties...... experienced by hens in distinguishing between nest boxes in long rows of identical boxes. Heterogeneity of nest boxes has therefore been suggested as a method to reduce gregarious nesting. To test this hypothesis two experiments were performed. Twelve groups of 13–15 ISA Warren hens 27 weeks of age were...... nesting was higher in experimental groups compared to control groups (P laying period did not differ between the experimental and control groups (P = 0.41). Numbers of visits to and eggs laid in nest boxes positioned either left or right were higher compared to nest boxes positioned...
7. Nest predation increases with parental activity: separating nest site and parental activity effects.
OpenAIRE
Martin, T E; Scott, J; Menge, C
2000-01-01
Alexander Skutch hypothesized that increased parental activity can increase the risk of nest predation. We tested this hypothesis using ten open-nesting bird species in Arizona, USA. Parental activity was greater during the nestling than incubation stage because parents visited the nest frequently to feed their young during the nestling stage. However, nest predation did not generally increase with parental activity between nesting stages across the ten study species. Previous investigators h...
8. Nest Predation Deviates from Nest Predator Abundance in an Ecologically Trapped Bird.
Science.gov (United States)
Hollander, Franck A; Van Dyck, Hans; San Martin, Gilles; Titeux, Nicolas
2015-01-01
In human-modified environments, ecological traps may result from a preference for low-quality habitat where survival or reproductive success is lower than in high-quality habitat. It has often been shown that low reproductive success for birds in preferred habitat types was due to higher nest predator abundance. However, between-habitat differences in nest predation may only weakly correlate with differences in nest predator abundance. An ecological trap is at work in a farmland bird (Lanius collurio) that recently expanded its breeding habitat into open areas in plantation forests. This passerine bird shows a strong preference for forest habitat, but it has a higher nest success in farmland. We tested whether higher abundance of nest predators in the preferred habitat or, alternatively, a decoupling of nest predator abundance and nest predation explained this observed pattern of maladaptive habitat selection. More than 90% of brood failures were attributed to nest predation. Nest predator abundance was more than 50% higher in farmland, but nest predation was 17% higher in forest. Differences between nest predation on actual shrike nests and on artificial nests suggested that parent shrikes may facilitate nest disclosure for predators in forest more than they do in farmland. The level of caution by parent shrikes when visiting their nest during a simulated nest predator intrusion was the same in the two habitats, but nest concealment was considerably lower in forest, which contributes to explaining the higher nest predation in this habitat. We conclude that a decoupling of nest predator abundance and nest predation may create ecological traps in human-modified environments.
9. DNest3: Diffusive Nested Sampling
Science.gov (United States)
Brewer, Brendon
2016-04-01
DNest3 is a C++ implementation of Diffusive Nested Sampling (ascl:1010.029), a Markov Chain Monte Carlo (MCMC) algorithm for Bayesian Inference and Statistical Mechanics. Relative to older DNest versions, DNest3 has improved performance (in terms of the sampling overhead, likelihood evaluations still dominate in general) and is cleaner code: implementing new models should be easier than it was before. In addition, DNest3 is multi-threaded, so one can run multiple MCMC walkers at the same time, and the results will be combined together.
10. Nested-cone transformer antenna
Science.gov (United States)
Ekdahl, Carl A.
1991-01-01
A plurality of conical transmission lines are concentrically nested to form n output antenna for pulsed-power, radio-frequency, and microwave sources. The diverging conical conductors enable a high power input density across a bulk dielectric to be reduced below a breakdown power density at the antenna interface with the transmitting medium. The plurality of cones maintain a spacing between conductors which minimizes the generation of high order modes between the conductors. Further, the power input feeds are isolated at the input while enabling the output electromagnetic waves to add at the transmission interface. Thus, very large power signals from a pulse rf, or microwave source can be radiated.
11. Polytypic Functions Over Nested Datatypes
Directory of Open Access Journals (Sweden)
Ralf Hinze
1999-12-01
Full Text Available The theory and practice of polytypic programming is intimately connected with the initial algebra semantics of datatypes. This is both a blessing and a curse. It is a blessing because the underlying theory is beautiful and well developed. It is a curse because the initial algebra semantics is restricted to so-called regular datatypes. Recent work by R. Bird and L. Meertens [3] on the semantics of non-regular or nested datatypes suggests that an extension to general datatypes is not entirely straightforward. Here we propose an alternative that extends polytypism to arbitrary datatypes, including nested datatypes and mutually recursive datatypes. The central idea is to use rational trees over a suitable set of functor symbols as type arguments for polytypic functions. Besides covering a wider range of types the approach is also simpler and technically less involving than previous ones. We present several examples of polytypic functions, among others polytypic reduction and polytypic equality. The presentation assumes some background in functional and in polytypic programming. A basic knowledge of monads is required for some of the examples.
12. Eggs in the Freezer: Energetic Consequences of Nest Site and Nest Design in Arctic Breeding Shorebirds
Science.gov (United States)
Tulp, Ingrid; Schekkerman, Hans; de Leeuw, Joep
2012-01-01
Birds construct nests for several reasons. For species that breed in the Arctic, the insulative properties of nests are very important. Incubation is costly there and due to an increasing surface to volume ratio, more so in smaller species. Small species are therefore more likely to place their nests in thermally favourable microhabitats and/or to invest more in nest insulation than large species. To test this hypothesis, we examined characteristics of nests of six Arctic breeding shorebird species. All species chose thermally favourable nesting sites in a higher proportion than expected on the basis of habitat availability. Site choice did not differ between species. Depth to frozen ground, measured near the nests, decreased in the course of the season at similar non-species-specific speeds, but this depth increased with species size. Nest cup depth and nest scrape depth (nest cup without the lining) were unrelated to body mass (we applied an exponent of 0.73, to account for metabolic activity of the differently sized species). Cup depth divided by diameter2 was used as a measure of nest cup shape. Small species had narrow and deep nests, while large species had wide shallow nests. The thickness of nest lining varied between 0.1 cm and 7.6 cm, and decreased significantly with body mass. We reconstruct the combined effect of different nest properties on the egg cooling coefficient using previously published quantitative relationships. The predicted effect of nest cup depth and lining depth on heat loss to the frozen ground did not correlate with body mass, but the sheltering effect of nest cup diameter against wind and the effects of lining material on the cooling coefficient increased with body mass. Our results suggest that small arctic shorebirds invest more in the insulation of their nests than large species. PMID:22701596
13. Nested Canalizing Functions and Their Networks
CERN Document Server
2014-01-01
The concept of a nested canalizing Boolean function has been studied over the last decade in the context of understanding the regulatory logic of molecular interaction networks, such as gene regulatory networks. Such networks are predominantly governed by nested canalizing functions. Derrida values are frequently used to analyze the robustness of a Boolean network to perturbations. This paper introduces closed formulas for the calculation of Derrida values of networks governed by Boolean nested canalizing functions, which previously required extensive simulations. Recently, the concept of nested canalizing functions has been generalized to include multistate functions, and a recursive formula has been derived for their number, as a function of the number of variables. This paper contains a detailed analysis of the class of nested canalizing functions over an arbitrary finite field. In addition, the concept of nested canalization is further generalized and closed formulas for the number of such generalized fun...
14. The design and function of birds' nests.
Science.gov (United States)
Mainwaring, Mark C; Hartley, Ian R; Lambrechts, Marcel M; Deeming, D Charles
2014-10-01
All birds construct nests in which to lay eggs and/or raise offspring. Traditionally, it was thought that natural selection and the requirement to minimize the risk of predation determined the design of completed nests. However, it is becoming increasingly apparent that sexual selection also influences nest design. This is an important development as while species such as bowerbirds build structures that are extended phenotypic signals whose sole purpose is to attract a mate, nests contain eggs and/or offspring, thereby suggesting a direct trade-off between the conflicting requirements of natural and sexual selection. Nest design also varies adaptively in order to both minimize the detrimental effects of parasites and to create a suitable microclimate for parents and developing offspring in relation to predictable variation in environmental conditions. Our understanding of the design and function of birds' nests has increased considerably in recent years, and the evidence suggests that nests have four nonmutually exclusive functions. Consequently, we conclude that the design of birds' nests is far more sophisticated than previously realized and that nests are multifunctional structures that have important fitness consequences for the builder/s.
15. Optimal Nesting for Continuous Shape Stamping Processes
Institute of Scientific and Technical Information of China (English)
2000-01-01
This paper discusses the optimal nesting problem for minimizing the scrap in continuous shape stamping processes. The shape sliding technique is used to propose a new approach, OVERLAP-and-ESCAPE, to solve the problem of continuously nesting shapes onto a metal coil of fixed or selectable width. The approach is used to construct the objective function of the mathematical model of the problem using the Simulated Annealing Algorithm to determine the globally minimal configurations for the nesting problems. Some representative cases are studied and the results are encouraging. An automatic nesting software package for manufacturing bicycle chain link blanks is also described.
16. Nest distribution and nest habitat of the Tibetan Partridge (Perdix hodgsoniae) near Lhasa, Tibet
Institute of Scientific and Technical Information of China (English)
Tsering; Dorge; G?ran; H?gstedt; Terje; Lislevand
2014-01-01
Background: Little is hitherto known about the breeding ecology of the Tibetan Partridge(Perdix hodgsoniae)which is endemic to the Tibetan plateau. Here we describe nest densities, inter-nest distances and general nest site characteristics in this gallinaceous bird species and explore the possibilities that certain shrub and plant types are preferred as nest surroundings.Method: A total of 56 nests were found over three breeding seasons near Lhasa, Tibet. Nest site characteristics were compared with random control plots and the proportions of specific plant species covering nests were compared with their estimated general occurrence in the study area.Results: Nest density in the two years with highest search effort was estimated at 1.43/km2 and 1.04/km2 but was clearly higher in the part of the study area facing north(1.86–2.35/km2) than that facing south(0.11–0.34/ km2). The average nearest neighbour distance of nests was about 300 m. Nests were situated in relatively lush vegetation and covered by a total of eight shrub species and three herbs. In contrast to previous reports, Caragana shrub did not constitute an important part of the nest habitat. The flowering, non-thorny bush Potentilla fruticosa was significantly over-represented as nest cover, while Rhododendron nivale was similarly under-represented. Nest bush foliage covered a larger area of ground, and the shrub surrounding nests was generally denser, than in control samples. Also, nests were placed closer to paths and in areas with lower densities of Yak(Bos grunniens) dung than in control samples.Except that soil temperatures were lower on nest sites than on control sites, micro-climate variables measured in this study did not differ between nest sites and control plots.Conclusions: Opportunity for nest concealment is probably an important quality of the nest habitat in Tibetan Partridges, yet it is unclear why the species should prefer P. fruticosa as nest cover. It is possible that nest sites are
17. Nest distribution and nest habitat of the Tibetan Partridge (Perdix hodgsoniae) near Lhasa, Tibet
Institute of Scientific and Technical Information of China (English)
Tsering Dorge; Gran Hgstedt; Terje Lislevand
2014-01-01
Background:Little is hitherto known about the breeding ecology of the Tibetan Partridge (Perdix hodgsoniae) which is endemic to the Tibetan plateau. Here we describe nest densities, inter-nest distances and general nest site characteristics in this gallinaceous bird species and explore the possibilities that certain shrub and plant types are preferred as nest surroundings. Method:A total of 56 nests were found over three breeding seasons near Lhasa, Tibet. Nest site characteristics were compared with random control plots and the proportions of specific plant species covering nests were compared with their estimated general occurrence in the study area. Results:Nest density in the two years with highest search effort was estimated at 1.43/km2 and 1.04/km2 but was clearly higher in the part of the study area facing north (1.86–2.35/km2) than that facing south (0.11–0.34/km2). The average nearest neighbour distance of nests was about 300 m. Nests were situated in relatively lush vegetation and covered by a total of eight shrub species and three herbs. In contrast to previous reports, Caragana shrub did not constitute an important part of the nest habitat. The flowering, non-thorny bush Potentil a fruticosa was significantly over-represented as nest cover, while Rhododendron nivale was similarly under-represented. Nest bush foliage covered a larger area of ground, and the shrub surrounding nests was generally denser, than in control samples. Also, nests were placed closer to paths and in areas with lower densities of Yak (Bos grunniens) dung than in control samples. Except that soil temperatures were lower on nest sites than on control sites, micro-climate variables measured in this study did not differ between nest sites and control plots. Conclusions:Opportunity for nest concealment is probably an important quality of the nest habitat in Tibetan Partridges, yet it is unclear why the species should prefer P. fruticosa as nest cover. It is possible that nest sites
18. Nested Trampoline Resonators for Optomechanics
CERN Document Server
Weaver, Matthew J; Luna, Fernando; Buters, Frank M; Eerkens, Hedwig J; Welker, Gesa; Perock, Blaise; Heeck, Kier; de Man, Sven; Bouwmeester, Dirk
2015-01-01
Two major challenges in the development of optomechanical devices are achieving a low mechanical and optical loss rate and vibration isolation from the environment. We address both issues by fabricating novel trampoline resonators made from low pressure chemical vapor deposition (LPCVD) Si$_3$N$_4$ with a distributed bragg reflector (DBR) mirror. We construct a nested double resonator structure that generates approximately 80 dB of mechanical isolation from the mounting surface, eliminating the strong mounting dependence of the quality factor observed with single resonators. With the consistency provided by this isolation scheme we reliably fabricate devices with mechanical quality factors of around 400,000 at room temperature. In addition these devices were used to form optical cavities with finesse up to 181,000 $\\pm$ 1,000. These promising parameters will enable experiments in the quantum regime with macroscopic mechanical resonators.
19. Nested trampoline resonators for optomechanics
Energy Technology Data Exchange (ETDEWEB)
Weaver, M. J., E-mail: [email protected]; Pepper, B.; Luna, F.; Perock, B. [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Buters, F. M.; Eerkens, H. J.; Welker, G.; Heeck, K.; Man, S. de [Huygens-Kamerlingh Onnes Laboratorium, Universiteit Leiden, 2333 CA Leiden (Netherlands); Bouwmeester, D. [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Huygens-Kamerlingh Onnes Laboratorium, Universiteit Leiden, 2333 CA Leiden (Netherlands)
2016-01-18
Two major challenges in the development of optomechanical devices are achieving a low mechanical and optical loss rate and vibration isolation from the environment. We address both issues by fabricating trampoline resonators made from low pressure chemical vapor deposition Si{sub 3}N{sub 4} with a distributed Bragg reflector mirror. We design a nested double resonator structure with 80 dB of mechanical isolation from the mounting surface at the inner resonator frequency, and we demonstrate up to 45 dB of isolation at lower frequencies in agreement with the design. We reliably fabricate devices with mechanical quality factors of around 400 000 at room temperature. In addition, these devices were used to form optical cavities with finesse up to 181 000 ± 1000. These promising parameters will enable experiments in the quantum regime with macroscopic mechanical resonators.
20. 1989 Waterfowl Nesting Study and Nesting Summary 1984-1989 : Big Stone National Wildlife Refuge
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — The 1989 nesting season marked the sixth consecutive and final year that Big Stone personnel have conducted waterfowl nesting research. In addition, an experimental...
1. Frog Foam Nest Protein Diversity and Synthesis.
Science.gov (United States)
Hissa, Denise Cavalcante; Bezerra, Walderly Melgaço; Freitas, Cléverson Diniz Teixeira De; Ramos, Márcio Viana; Lopes, José Luiz De Souza; Beltramini, Leila Maria; Roberto, Igor Joventino; Cascon, Paulo; Melo, Vânia Maria Maciel
2016-08-01
Some amphibian species have developed a breeding strategy in which they deposit their eggs in stable foam nests to protect their eggs and larvae. The frog foam nests are rich in proteins (ranaspumin), especially surfactant proteins, involved in the production of the foam nest. Despite the ecological importance of the foam nests for evolution and species conservation, the biochemical composition, the long-term stability and even the origin of the components are still not completely understood. Recently we showed that Lv-RSN-1, a 23.5-kDa surfactant protein isolated from the nest of the frog Leptodacylus vastus, presents a structural conformation distinct from any protein structures yet reported. So, in the current study we aimed to reveal the protein composition of the foam nest of L. vastus and further characterize the Lv-RSN-1. Proteomic analysis showed the foam nest contains more than 100 of proteins, and that Lv-RSN-1 comprises 45% of the total proteins, suggesting a key role in the nest construction and stability. We demonstrated by Western blotting that Lv-RSN-1 is mainly produced only by the female in the pars convoluta dilata, which highlights the importance of the female preservation for conservation of species that depend on the production of foam nests in the early stages of development. Overall, our results showed the foam nest of L. vastus is composed of a great diversity of proteins and that besides Lv-RSN-1, the main protein in the foam, other proteins must have a coadjuvant role in building and stability of the nest.
2. Aromatic Plants in Eurasian Blue Tit Nests: The ‘Nest
OpenAIRE
Pires, Bárbara A.; Anabela F. Belo; Rabaça, João E.
2012-01-01
The ‘Nest Protection Hypothesis’ suggests that some birds add aromatic plants to their nests to repel or kill ectoparasites. This behavior has been described for several species, including the Eurasian Blue Tit (Cyanistes caeruleus). We studied the reproductive performance, based on 26 nests (in nest boxes), of this species in mixed forested areas of Quercus spp. and Pinus pinea in the Parque Florestal de Monsanto, the largest park of Lisbon, Portugal. The frequency of aromatic plant...
3. Florida harvester ant nest architecture, nest relocation and soil carbon dioxide gradients.
Science.gov (United States)
Tschinkel, Walter R
2013-01-01
4. Chapter 6: Characteristics of Marbled Murrelet Nest Trees and Nesting Stands
Science.gov (United States)
Thomas E. Hamer; S. Kim Nelson
1995-01-01
We summarize the characteristics of 61 tree nests and nesting stands of the Marbled Murrelet ( Brachyramphus marmoratus ) located from 1974 to 1993 in Alaska, British Columbia, Washington, Oregon, and California. Evidence of breeding 30-60 km inland was common in California, Oregon, and Washington. Nesting greater distances from the coast may have...
5. Landscape forest cover and edge effects on songbird nest predation vary by nest predator
Science.gov (United States)
W. Andrew Cox; Frank R. III Thompson; John. Faaborg
2012-01-01
Rates of nest predation for birds vary between and within species across multiple spatial scales, but we have a poor understanding of which predators drive such patterns. We video-monitored nests and identified predators at 120 nests of the Acadian Flycatcher (Empidonax virescens) and the Indigo Bunting (Passerina cyanea) at eight...
6. Waterbird nest-site selection is influenced by neighboring nests and island topography
Science.gov (United States)
Hartman, Christopher; Ackerman, Josh; Takekawa, John Y.; Herzog, Mark
2016-01-01
Avian nest-site selection is influenced by factors operating across multiple spatial scales. Identifying preferred physical characteristics (e.g., topography, vegetation structure) can inform managers to improve nesting habitat suitability. However, social factors (e.g., attraction, territoriality, competition) can complicate understanding physical characteristics preferred by nesting birds. We simultaneously evaluated the physical characteristics and social factors influencing selection of island nest sites by colonial-nesting American avocets (Recurvirostra americana) and Forster's terns (Sterna forsteri) at 2 spatial scales in San Francisco Bay, 2011–2012. At the larger island plot (1 m2) scale, we used real-time kinematics to produce detailed topographies of nesting islands and map the distribution of nests. Nesting probability was greatest in island plots between 0.5 m and 1.5 m above the water surface, at distances less likely to nest in plots adjacent to plots with nesting avocets, suggesting an influence of intra-specific territoriality. At the smaller microhabitat scale, or the area immediately surrounding the nest, we compared topography, vegetation, and distance to nearest nest between nest sites and paired random sites. Topography had little influence on selection of the nest microhabitat. Instead, nest sites were more likely to have vegetation present, and greater cover, than random sites. Finally, avocet, and to a lesser extent tern, nest sites were closer to other active conspecific or heterospecific nests than random sites, indicating that social attraction played a role in selection of nest microhabitat. Our results demonstrate key differences in nest-site selection between co-occurring avocets and terns, and indicate the effects of physical characteristics and social factors on selection of nesting habitat are dependent on the spatial scale examined. Moreover, these results indicate that islands with abundant area between 0.5 m and 1.5
7. Conservation significance of alternative nests of golden eagles
Directory of Open Access Journals (Sweden)
Brian A. Millsap
2015-01-01
Full Text Available Golden eagles (Aquila chrysaetos are long-lived raptors that maintain nesting territories that may be occupied for a century or longer. Within occupied nesting territories there is one nest in which eagles lay their eggs in a given year (i.e., the used nest, but there are usually other nests (i.e., alternative nests. Conservation plans often protect used nests, but not alternative nests or nesting territories that appear vacant. Our objective is to review literature on golden eagle use of alternative nests and occupancy of nesting territories to determine if alternative nests are biologically significant and warrant greater conservation consideration. Our review shows that: (1 alternative nests or their associated habitat are most often in core areas of golden eagle nesting territories; (2 alternative nests likely will become used in the future; (3 probability of an alternative nest becoming used is greatest where prey availability is high and alternative nest sites are limited; (4 likelihood of annual occupancy or reoccupancy of golden eagle nesting territories is high; and (5 prey availability is the most important determinant of nesting territory occupancy and breeding activity. We recommend alternative nests be treated with the same deference as used nests in land use planning.
8. 7 CFR 29.6027 - Nested.
Science.gov (United States)
2010-01-01
... 7 Agriculture 2 2010-01-01 2010-01-01 false Nested. 29.6027 Section 29.6027 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6027 Nested. Any tobacco which has been loaded, packed, or arranged...
9. Dune vegetation fertilization by nesting sea turtles.
Science.gov (United States)
Hannan, Laura B; Roth, James D; Ehrhart, Llewellyn M; Weishampel, John F
2007-04-01
Sea turtle nesting presents a potential pathway to subsidize nutrient-poor dune ecosystems, which provide the nesting habitat for sea turtles. To assess whether this positive feedback between dune plants and turtle nests exists, we measured N concentration and delta15N values in dune soils, leaves from a common dune plant (sea oats [Uniola paniculata]), and addled eggs of loggerhead (Caretta caretta) and green turtles (Chelonia mydas) across a nesting gradient (200-1050 nests/km) along a 40.5-km stretch of beach in east central Florida, USA. The delta15N levels were higher in loggerhead than green turtle eggs, denoting the higher trophic level of loggerhead turtles. Soil N concentration and delta15N values were both positively correlated to turtle nest density. Sea oat leaf tissue delta15N was also positively correlated to nest density, indicating an increased use of augmented marine-based nutrient sources. Foliar N concentration was correlated with delta15N, suggesting that increased nutrient availability from this biogenic vector may enhance the vigor of dune vegetation, promoting dune stabilization and preserving sea turtle nesting habitat.
10. a 530-590 GHZ Schottky Heterodyne Receiver for High-Resolution Molecular Spectroscopy with Lille's Fast-Scan Fully Solid-State DDS Spectrometer
Science.gov (United States)
Pienkina, A.; Margulès, L.; Motiyenko, R. A.; Wiedner, Martina C.; Maestrini, Alain; Defrance, Fabien
2017-06-01
Laboratory spectroscopy, especially at THz and mm-wave ranges require the advances in instrumentation techniques to provide high resolution of the recorded spectra with precise frequency measurement that facilitates the mathematical treatment. We report the first implementation of a Schottky heterodyne receiver, operating at room temperature and covering the range between 530 and 590 GHz, for molecular laboratory spectroscopy. A 530-590 GHz non-cryogenic Schottky solid-state receiver was designed at LERMA, Observatoire de Paris and fabricated in partnership with LPN- CNRS (Laboratoire de Photonique et de Nanostructures), and was initially developed for ESA Jupiter Icy Moons Explorer (JUICE), intended to observe Jupiter and its icy moon atmospheres. It is based on a sub-harmonic Schottky diode mixer, designed and fabricated at LERMA-LPN, pumped by a Local Oscillator (LO), consisting of a frequency Amplifier/Multiplier chains (AMCs) from RPG (Radiometer Physics GmBh). The performance of the receiver was demonstrated by absorption spectroscopy of CH_3CH_2CN with Lille's fast-scan DDS spectrometer. A series of test measurements showed the receiver's good sensitivity, stability and frequency accuracy comparable to those of 4K QMC bolometers, thus making room-temperature Schottky receiver a competitive alternative to 4K QMC bolometers to laboratory spectroscopy applications. We will present the first results with such a combination of a compact room temperature Schottky heterodyne receiver and a fast-scan DDS spectrometer. J. Treuttel, L. Gatilova, A. Maestrini et al., 2016, IEEE Trans. Terahertz Science and Tech., 6, 148-155. This work was funded by the French ANR under the Contract No. ANR-13-BS05-0008-02 IMOLABS.
11. Dinosaurs nesting on a red beach?
Science.gov (United States)
Sander, P. Martin; Peitz, Christian; Gallemi, Jaume; Cousin, Rémi
1998-07-01
The Upper Cretaceous Basturs locality (Tremp Basin, northern Spain) preserves numerous dinosaur eggs ( Megaloolithus cf. M. mammilare Vianey-Liaud, 1994). The locality was recently studied by Sanz et al. (1995) as well as by us. However, we have to disagree with several conclusions by Sanz et al. and suggest alternative interpretations incorporating data from other localities (Coll de Nargó). The dinosaurs at Basturs did not nest at the beach, nor is there evidence for colonial nesting and territorial behaviour. However, the locality superbly documents nesting site fidelity with an estimated occupation time of over 10 000 years.
12. Emperor penguins nesting on Inaccessible Island
Science.gov (United States)
Jonkel, G.M.; Llano, G.A.
1975-01-01
Emperor penguins were observed nesting on Inaccessible I. during the 1973 winter. This is the southernmost nesting of emperor penguins thus far recorded; it also could be the first record of emperors attempting to start a new rookery. This site, however, may have been used by emperors in the past. The closest reported nesting of these penguins to Inaccessible I. is on the Ross Ice Shelf east of Cape Crozier. With the exception of the Inaccessible I. record, there is little evidence that emperor penguins breed in McMurdo Sound proper.
13. 1988 Duck nesting study: Stillwater Wildlife Management Area
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — During the summer, 1988, we conducted a duck nesting study to determine nest success for ducks at Stillwater Wildlife Management Area (WMA). We calculated nest...
14. Nest site characteristics and nesting success of the Western Burrowing Owl in the eastern Mojave Desert
Science.gov (United States)
Longshore, Kathleen M.; Crowe, Dorothy E.
2013-01-01
We evaluated nest site selection at two spatial scales (microsite, territory) and reproductive success of Western Burrowing Owls (Athene cunicularia hypugaea) at three spatial scales (microsite, territory, landscape) in the eastern Mojave Desert. We used binary logistic regression within an information-theoretic approach to assess factors influencing nest site choice and nesting success. Microsite-scale variables favored by owls included burrows excavated by desert tortoise (Gopherus agassizii), burrows with a large mound of excavated soil at the entrance, and a greater number of satellite burrows within 5 m of the nest burrow. At the territory scale, owls preferred patches with greater cover of creosote bush (Larrea tridentata) within 50 m of the nest burrow. An interaction between the presence or absence of a calcic soil horizon layer over the top of the burrow (microsite) and the number of burrows within 50 m (territory) influenced nest site choice. Nesting success was influenced by a greater number of burrows within 5 m of the nest burrow. Total cool season precipitation was a predictor of nesting success at the landscape scale. Conservation strategies can rely on management of habitat for favored and productive nesting sites for this declining species.
15. The nest as fortress: Defensive behavior of Polybia emaciata, a mud-nesting eusocial wasp
Directory of Open Access Journals (Sweden)
Sean O'Donnell
2002-02-01
Full Text Available The swarm-founding wasp Polybia emaciata is unusual among eusocial Vespidae because it uses mud, rather than wood pulp, as its primary nest construction material. Polybia emaciata nests are more durable than similarly sized paper nests. We tested the hypothesis that the defensive behavior of this wasp may have been modified to take advantage of their strong nests in defense against vertebrate attacks. We simulated vertebrate disturbances by tapping on, and breathing in, P. emaciata. nests and similarly sized P. occidentalis paper nests in the same location at the same time. Polybia emaciata. responses to disturbance were qualitatively different from those of P. occidentalis. The latter exit the nest and attack, while P. emaciata. workers typically fled or entered the nest, attacking only after repeated and extended disturbances. We conclude that durable nest material may permit predator avoidance behavior in P. emaciata.. We compare the defensive responses of P. emaciata. workers with those of other swarm-founding Vespidae, and discuss several selective forces that could cause the evolution of species variation in nest defense behavior.
16. Estimating stage-specific daily survival probabilities of nests when nest age is unknown
Science.gov (United States)
Stanley, T.R.
2004-01-01
Estimation of daily survival probabilities of nests is common in studies of avian populations. Since the introduction of Mayfield's (1961, 1975) estimator, numerous models have been developed to relax Mayfield's assumptions and account for biologically important sources of variation. Stanley (2000) presented a model for estimating stage-specific (e.g. incubation stage, nestling stage) daily survival probabilities of nests that conditions on “nest type” and requires that nests be aged when they are found. Because aging nests typically requires handling the eggs, there may be situations where nests can not or should not be aged and the Stanley (2000) model will be inapplicable. Here, I present a model for estimating stage-specific daily survival probabilities that conditions on nest stage for active nests, thereby obviating the need to age nests when they are found. Specifically, I derive the maximum likelihood function for the model, evaluate the model's performance using Monte Carlo simulations, and provide software for estimating parameters (along with an example). For sample sizes as low as 50 nests, bias was small and confidence interval coverage was close to the nominal rate, especially when a reduced-parameter model was used for estimation.
17. Spatial dynamics of nesting behavior: lizards shift microhabitats to construct nests with beneficial thermal properties.
Science.gov (United States)
Angilletta, Michael J; Sears, Michael W; Pringle, Robert M
2009-10-01
Because temperature affects the growth, development, and survival of embryos, oviparous mothers should discriminate carefully among available nesting sites. We combined a radiotelemetric study of animal movements with a spatial mapping of environmental temperatures to test predictions about the nesting behavior of the eastern fence lizard (Sceloporus undulatus). Females made large excursions from their typical home ranges to construct nests in exposed substrates. These excursions appeared to be related solely to nesting because all females returned to forested habitat immediately afterward. On average, <1% (range = 0-8%, n = 19) of the area used by a female during nesting was contained within the area used before and after nesting. The selection of nesting sites matched predictions based on laboratory studies of embryonic performance; specifically, females nested in extremely open habitat at a mean of 6 cm depth. Spatial mapping of soil temperatures revealed that temperatures of nesting areas exceeded those of areas typically used by females, indicating that females preferred to construct warm nests that speed embryonic growth and development. However, this behavior could reduce the survivorship of females because of the need to rapidly navigate unfamiliar and exposed terrain.
18. Construction patterns of birds’ nests provide insight into nest-building behaviours
Science.gov (United States)
2017-01-01
Previous studies have suggested that birds and mammals select materials needed for nest building based on their thermal or structural properties, although the amounts or properties of the materials used have been recorded for only a very small number of species. Some of the behaviours underlying the construction of nests can be indirectly determined by careful deconstruction of the structure and measurement of the biomechanical properties of the materials used. Here we examined this idea in an investigation of Bullfinch (Pyrrhula pyrrhula) nests as a model for open-nesting songbird species that construct a “twig” nest, and tested the hypothesis that materials in different parts of nests serve different functions. The quantities of materials present in the nest base, sides and cup were recorded before structural analysis. Structural analysis showed that the base of the outer nests were composed of significantly thicker, stronger and more rigid materials compared to the side walls, which in turn were significantly thicker, stronger and more rigid than materials used in the cup. These results suggest that the placement of particular materials in nests may not be random, but further work is required to determine if the final structure of a nest accurately reflects the construction process. PMID:28265501
19. Construction patterns of birds’ nests provide insight into nest-building behaviours
Directory of Open Access Journals (Sweden)
Lucia Biddle
2017-02-01
Full Text Available Previous studies have suggested that birds and mammals select materials needed for nest building based on their thermal or structural properties, although the amounts or properties of the materials used have been recorded for only a very small number of species. Some of the behaviours underlying the construction of nests can be indirectly determined by careful deconstruction of the structure and measurement of the biomechanical properties of the materials used. Here we examined this idea in an investigation of Bullfinch (Pyrrhula pyrrhula nests as a model for open-nesting songbird species that construct a “twig” nest, and tested the hypothesis that materials in different parts of nests serve different functions. The quantities of materials present in the nest base, sides and cup were recorded before structural analysis. Structural analysis showed that the base of the outer nests were composed of significantly thicker, stronger and more rigid materials compared to the side walls, which in turn were significantly thicker, stronger and more rigid than materials used in the cup. These results suggest that the placement of particular materials in nests may not be random, but further work is required to determine if the final structure of a nest accurately reflects the construction process.
20. Alcid Nesting Habitat on the Maine Coast
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Maine supports an extensive seabird population because of the abundance of relatively inaccessible rocky coastal islands which are ideal nesting grounds for many...
Science.gov (United States)
... clinical diagnosis. Instead, empty nest syndrome is a phenomenon in which parents experience feelings of sadness and loss when the last child leaves home. Although you might actively encourage your ...
2. Annual survival of Florida nesting loggerheads
Data.gov (United States)
National Oceanic and Atmospheric Administration, Department of Commerce — 30 PAT tags were deployed on nesting loggerhead turtles at Juno Beach, FL in June 2012. There have been three premature pop-offs, one of which appeared to be a...
3. Cackling Canada goose nesting populations, Yukon Delta
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Number of potential territories, number of cackling Canada Goose nests, and percent occupancy of available territories from CCG plots on the Yukon Delta National...
4. Starling nest box monitoring [Rocky Mountain Arsenal
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This document described the standard operating procedures for observing and recording data collected from starling nest box monitoring at the Rocky Mountain Arsenal....
5. Chesapeake Bay Bald Eagle Nesting Survey
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — The Chesapeake Bay population of breeding bald eagles increased dramatically in 1981 in not only the number of breeding pairs but in the number of nests hatching...
6. Island's terns nest again after unsuccessful start
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — For five consecutive summers the Trustees of Reservations have directed a program on Nantucket for the protection of the terns which nest in several colonies around...
7. Duck-nesting Studies: Lower Souris Refuge
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — In this report an attempt has been made to summarize some of the notes made during the nesting studies at the Lower Souris Refuge in 1937. While assisting Mr....
8. Nesting Loggerhead Sea Turtle Activity Report 2001
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This paper presents results from the 9th Annual Study (using Army Corp of Engineers funds) of nesting by the Atlantic loggerhead sea turtle (Caretta caretta) along...
9. Nesting Loggerhead Sea Turtle Activity Report 1998
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This paper presents results from the sixth annual study of nesting along the Atlantic Oceanfront by the loggerhead sea turtle (Caretta carettd) in Virginia Beach,...
10. Nesting Loggerhead Sea Turtle Activity Report 1999
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This paper presents results from the seventh annual study (using Army Corp of Engineers funds;) of nesting along the Atlantic Ocean coastline by the loggerhead sea...
11. Linear Maps Preserving Idempotence on Nest Algebras
Institute of Scientific and Technical Information of China (English)
Jian Lian CUI; Jin Chuan HOU
2004-01-01
In this paper, we discuss the rank-1-preserving linear maps on nest algebras of Hilbertspace operators. We obtain several characterizations of such linear maps and apply them to show that a weakly continuous linear bijection on an atomic nest algebra is idempotent preserving if and only if it is a Jordan homomorphism, and in turn, if and only if it is an automorphism or an anti-automorphism.
12. Helga-Jane Scarwell et Isabelle Roussel (dir., 2010, Le changement climatique : Quand le climat nous pousse à changer d’ère, Presses Universitaire du Septentrion, Lille, 358 pages
Directory of Open Access Journals (Sweden)
Laurence Rocher
2010-12-01
Full Text Available L’ouvrage « Le changement climatique. Quand le climat nous pousse à changer d’ère », édité par les Presses Universitaire du Septentrion dans la collection Environnement et société, coordonné par Helga-Jane Scarwell et Isabelle Roussel, rassemble autour de la question du changement climatique plusieurs contributions de chercheurs en géographie, pour la plupart membres du laboratoire TVES de Lille. Ce livre apporte un éclairage original et intéressant, alliant des études de cas comportant un fo...
13. Gregarious nesting - An anti-predator response in laying hens
DEFF Research Database (Denmark)
Riber, Anja Brinch
2012-01-01
Gregarious nesting can be defined as a behaviour that occurs when a laying hen (Gallus gallus domesticus) given the choice between an occupied and an unoccupied nest site chooses the occupied nest site. It occurs frequently in flocks of laying hens kept under commercial conditions, contrasting...... the behaviour displayed by feral hens that isolate themselves from the flock during nesting activities. What motivates laying hens to perform gregarious nesting is unknown. One possibility is that gregarious nesting is an anti-predator response to the risk of nest predation emerging from behavioural flexibility...... in nesting strategy. The aim of the present experiment was to investigate whether gregarious nesting due to behavioural flexibility in nesting strategy is an anti-predator response. Twelve groups of 14–15 Isa Warren hens age 44 weeks were housed in pens each containing three adjacent roll-out nest boxes...
14. Nest-site limitation and nesting resources of ants (Hymenoptera: Formicidae) in urban green spaces.
Science.gov (United States)
Friedrich, Russell; Philpott, Stacy M
2009-06-01
Urbanization impacts biodiversity, yet few studies examine general impacts of urbanization on insects. Furthermore, few studies examine availability and limitation of potential cavity nesting sites for ants, an important regulating factor in ant communities that may vary in different urban habitats. We compared three urban habitat types (gardens, vacant lots, and forests) in Toledo, OH, to examine availability and ant preferences for different cavity nesting resources (small and large hollow twigs and cavities). We added 72 artificial large hollow twigs (83 by 6 mm), small hollow twigs (140 by 2 mm), and spherical hollow cavities (6.52-31.1 cm(3) in volume, 1-mm opening) to six sites from May to August 2007 to determine whether nest-site limitation impacts ant communities. We collected natural nests to compare natural abundance and occupancy of cavity nests in different urban habitats. We opened artificial and natural nests to calculate the percentage occupied by cavity-nesting ants. Across all habitats, small twigs represented 81.1% of natural nests, spherical nests represented 10.1%, and large twigs 8.2%. Ants occupied 8.1% of natural large twigs, 14.6% of cavities, and 4.1% of small twigs. For artificial nests, 21.5% of large twigs, 1% of small twigs, and 1% of spheres were occupied. The high percentage of occupied artificial large twigs could imply this is a preferred and limiting resource in urban habitats. The results show that certain types of nesting resources may be an important factor mediating ant communities in urban green spaces.
15. Nesting Activity of Loggerhead Turtles (Caretta caretta at Göksu Delta, Turkey during 2004 and 2008 nesting seasons
Directory of Open Access Journals (Sweden)
Salih H. Durmus
2011-07-01
Full Text Available Göksu Delta is one of the most important nesting beaches in Turkey for the endangered loggerhead turtle (Caretta caretta. This paper provides information on the nesting activities of loggerhead turtles, the spatial and temporal distribution of nesting, nesting success, nesting density, hatching success, incubation duration and clutch size over two nesting seasons. A total of 902 emergences occurred over two seasons, of which 239 (26.5% nests were deposited (137 nests in 2004 and 102 nests in 2008 and the overall mean nesting density was 3.4 nests/km. The peak of nesting emergences takes place mainly in June. Of the overall nests, 226 (94.6% were excavated and 16044 eggs were counted. Of these eggs, 3680 (22.9% hatchlings emerged and 2695 (73.2% of hatchlings of them were able to reach the sea. The mean number of eggs per clutch was 71 (range: 15 – 143. The shortest and longest incubation duration in these 2 seasons ranged from 46 to 62 days with a mean of 53 days. The main problems are negatively affecting loggerhead turtle population at Göksu Delta are dense jackal predation both adult and eggs and inundation in nests. The average nesting effort here (mean: 119.5 nests/season confirms that Göksu Delta is one of the most important nesting sites for loggerhead turtles in Turkey.
16. The effects of large beach debris on nesting sea turtles
Science.gov (United States)
Fujisaki, Ikuko; Lamont, Margaret M.
2016-01-01
A field experiment was conducted to understand the effects of large beach debris on sea turtle nesting behavior as well as the effectiveness of large debris removal for habitat restoration. Large natural and anthropogenic debris were removed from one of three sections of a sea turtle nesting beach and distributions of nests and false crawls (non-nesting crawls) in pre- (2011–2012) and post- (2013–2014) removal years in the three sections were compared. The number of nests increased 200% and the number of false crawls increased 55% in the experimental section, whereas a corresponding increase in number of nests and false crawls was not observed in the other two sections where debris removal was not conducted. The proportion of nest and false crawl abundance in all three beach sections was significantly different between pre- and post-removal years. The nesting success, the percent of successful nests in total nesting attempts (number of nests + false crawls), also increased from 24% to 38%; however the magnitude of the increase was comparably small because both the number of nests and false crawls increased, and thus the proportion of the nesting success in the experimental beach in pre- and post-removal years was not significantly different. The substantial increase in sea turtle nesting activities after the removal of large debris indicates that large debris may have an adverse impact on sea turtle nesting behavior. Removal of large debris could be an effective restoration strategy to improve sea turtle nesting.
17. 50 CFR 22.27 - Removal of eagle nests.
Science.gov (United States)
2010-10-01
... 50 Wildlife and Fisheries 6 2010-10-01 2010-10-01 false Removal of eagle nests. 22.27 Section 22... WILDLIFE AND PLANTS (CONTINUED) EAGLE PERMITS Eagle Permits § 22.27 Removal of eagle nests. (a) Purpose and... active or inactive nest where necessary to alleviate a safety emergency; (ii) An inactive eagle nest...
18. Nested Canalyzing, Unate Cascade, and Polynomial Functions.
Science.gov (United States)
Jarrah, Abdul Salam; Raposa, Blessilda; Laubenbacher, Reinhard
2007-09-15
This paper focuses on the study of certain classes of Boolean functions that have appeared in several different contexts. Nested canalyzing functions have been studied recently in the context of Boolean network models of gene regulatory networks. In the same context, polynomial functions over finite fields have been used to develop network inference methods for gene regulatory networks. Finally, unate cascade functions have been studied in the design of logic circuits and binary decision diagrams. This paper shows that the class of nested canalyzing functions is equal to that of unate cascade functions. Furthermore, it provides a description of nested canalyzing functions as a certain type of Boolean polynomial function. Using the polynomial framework one can show that the class of nested canalyzing functions, or, equivalently, the class of unate cascade functions, forms an algebraic variety which makes their analysis amenable to the use of techniques from algebraic geometry and computational algebra. As a corollary of the functional equivalence derived here, a formula in the literature for the number of unate cascade functions provides such a formula for the number of nested canalyzing functions.
19. Nest survival patterns in Eurasian Bittern: effect of nest age, time and habitat variables
Directory of Open Access Journals (Sweden)
Marcin Polak
2016-06-01
Full Text Available Determining the key factors affecting the reproductive success of nesting birds is crucial in order to better understand the population dynamics of endangered species and to introduce effective conservation programmes for them. Inhabiting a variety of wetland habitats, aquatic birds actively select safe nesting sites so as to protect their nests against predators. The main aim of the present work was to assess the effect of temporal and habitat variables on the daily nest survival rate of Eurasian Bitterns colonizing semi–natural fishpond habitat in eastern Poland. MARK software was used for the modelling. Eurasian Bittern nests were most vulnerable to depredation at the beginning of the breeding season. This was probably because the reedbed vegetation at this time was not yet dense enough to effectively conceal the nests. There was a positive relationship between nest age and the daily survival rate. Two of the habitat variables analysed were of the greatest significance: water depth and vegetation density. In the Eurasian Bittern population studied here, nests built over deep water and in dense vegetation had the best chances of survival. The results of this work may be useful in the preparation of plans for the conservation and management of populations of this rare and endangered species. Conservation and restoration efforts that attempt to maintain high water levels will be especially beneficial to this avian species that is dependent on wetland ecosystems for breeding.
20. The influence of regional hydrology on nesting behavior and nest fate of the American alligator
Science.gov (United States)
Ugarte, Cristina A.; Bass, Oron L.; Nuttle, William; Mazzotti, Frank J.; Rice, Kenneth G.; Fujisaki, Ikuko; Whelan, Kevin R.T.
2013-01-01
Hydrologic conditions are critical to the nesting behavior and reproductive success of crocodilians. In South Florida, USA, growing human settlement has led to extensive surface water management and modification of historical water flows in the wetlands, which have affected regional nesting of the American alligator (Alligator mississippiensis). Although both natural and anthropogenic factors are considered to determine hydrologic conditions, the aspects of hydrological patterns that affect alligator nest effort, flooding (partial and complete), and failure (no hatchling) are unclear. We deconstructed annual hydrological patterns using harmonic models that estimated hydrological matrices including mean, amplitude, timing of peak, and periodicity of surface water depth and discharge and examined their effects on alligator nesting using survey data from Shark Slough, Everglades National Park, from 1985 to 2005. Nest effort increased in years with higher mean and lesser periodicity of water depth. A greater proportion of nests were flooded and failed when peak discharge occurred earlier in the year. Also, nest flooding rates were greater in years with greater periodicity of water depth, and nest failure rate was greater when mean discharge was higher. This study guides future water management decisions to mitigate negative impacts on reproduction of alligators and provides wildlife managers with a tool for assessing and modifying annual water management plans to conserve crocodilians and other wetland species.
1. Behavior of Puerto Rican parrots during failed nesting attempts
Science.gov (United States)
Wilson, K.A.; Wilson, M.H.; Field, R.
1997-01-01
We compared patterns of nesting behavior of four pairs of Puerto Rican Parrots (Amazona vittata) that experienced failed nesting attempts to behavior of four pairs of parrots that experienced no substantial nest problems and successfully fledged young without management intervention. Only changes in female parrots' behavior were clearly associated with nest failure. During incubation, decreases in nest attendance, increases in duration of recesses, and increases in frequency of nest entries by female parrots were associated with imminent abandonment of nests. During early chick rearing, similar behavior was associated with the loss of broods. Low nest attendance and long recesses by female parrots during incubation were also associated with successful hatching of eggs followed by death of young several days later. The behavior patterns and changes in Puerto Rican Parrot nesting behavior described in this paper may alert biologists to nest problems that might be mitigated by management intervention.
2. Buteo Nesting Ecology: Evaluating Nesting of Swainson’s Hawks in the Northern Great Plains
Science.gov (United States)
Inselman, Will M.; Datta, Shubham; Jenks, Jonathan A.; Jensen, Kent C.; Grovenburg, Troy W.
2015-01-01
Swainson’s hawks (Buteo swainsoni) are long-distance migratory raptors that nest primarily in isolated trees located in areas of high grassland density. In recent years, anthropogenic conversion of grassland habitat has raised concerns about the status of the breeding population in the northern Great Plains. In 2013, we initiated a study to investigate the influence of extrinsic factors influencing Swainson’s hawk nesting ecology in north-central South Dakota and south-central North Dakota. Using ground and aerial surveys, we located and monitored nesting Swainson’s hawk pairs: 73 in 2013 and 120 in 2014. We documented 98 successful breeding attempts that fledged 163 chicks; 1.52 and 1.72 fledglings per successful nest in 2013 and 2014, respectively. We used Program MARK to evaluate the influence of land cover on nest survival. The top model, SDist2Farm+%Hay, indicated that nest survival (fledging at least one chick) decreased as nests were located farther from farm sites and as the percent of hay cover increased within 1200-m of the nest site (34.4%; 95% CI = 27.6%–42.3%). We used logistic regression analysis to evaluate the influence of landscape variables on nest-site selection; Swainson’s hawks selected for nest sites located closer to roads. We suggest that tree belts associated with farm sites, whether occupied or not, provide critical breeding sites for Swainson’s hawks. Additionally, poor breeding success may be related to the late migratory behavior of this species which requires them to occupy marginal habitat due to other raptors occupying the most suitable habitat prior to Swainson’s hawks arriving to the breeding grounds. PMID:26327440
3. Nest-site selection, nesting behaviour and spatial ecology of female Nile crocodiles (Crocodylus niloticus) in South Africa.
Science.gov (United States)
Combrink, Xander; Warner, Jonathan K; Downs, Colleen T
2017-02-01
Nesting biology and ecology have been investigated for Nile crocodiles (Crocodylus niloticus), but information on behaviour and movement patterns of nesting females during nest guarding is scant. Consequently, we investigated the home ranges, nest-site selection strategies, movement patterns, activity levels and nest fidelity of four nesting females using telemetry. Gravid females selected winter basking/breeding areas close (351±2m) to nest-sites. Mean home range and core-use areas of nesting females were 8539±4752m(2), and 4949±3302m(2) respectively. Mean home range (0.85ha) was significantly smaller than those of non-nesting females (108.4ha) during nesting season. Activity levels and mean daily movements while nesting were 8.1±2.5% and 213±64m, respectively, and increased to 47.9±11.7% and 2176±708m post-nesting. Overall levels of nest fidelity were 82.8±11.7%, (day 78.1±15.9%; night 87.3±7.8%). Highest nest fidelity recorded during incubation was 99.7% over 96days. Telemetry data from nesting females were helpful for elucidating spatial and behavioural patterns during the nest guarding period, and provided novel insights into this biologically important event.
4. Boolean nested canalizing functions: a comprehensive analysis
CERN Document Server
Li, Yuan; Murrugarra, David; Aguilar, Boris; Laubenbacher, Reinhard
2012-01-01
Boolean network models of molecular regulatory networks have been used successfully in computational systems biology. The Boolean functions that appear in published models tend to have special properties, in particular the property of being nested canalizing, a property inspired by the concept of canalization in evolutionary biology. It has been shown that networks comprised of nested canalizing functions have dynamic properties that make them suitable for modeling molecular regulatory networks, namely a small number of (large) attractors, as well as relatively short limit cycles. This paper contains a detailed analysis of this class of functions, based on a novel normal form as polynomial functions over the Boolean field. The concept of layer is introduced that stratifies variables into different classes depending on their level of dominance. Using this layer concept a closed form formula is derived for the number of nested canalizing functions with a given number of variables. Additional metrics analyzed in...
5. Ashtabula Breakwater Common Tern (Sterna Hirundo) Nesting
Science.gov (United States)
2016-05-01
purchased from GG Telecom, Victoriaville, QC, Canada and connected to the solar panel system to help document activities at the site. Volunteers...blocks. Large 8’ x 8’ x 4’ blocks were used to form the base or toe of the structure, and smaller angled blocks were used to create the side slope...to nest. In addition to placing the blocks on top of the wall, lengths of angle iron were bolted down to attach the nesting blocks to those below
6. PolyChord: nested sampling for cosmology
CERN Document Server
Handley, W J; Lasenby, A N
2015-01-01
PolyChord is a novel nested sampling algorithm tailored for high dimensional parameter spaces. In addition, it can fully exploit a hierarchy of parameter speeds such as is found in CosmoMC and CAMB. It utilises slice sampling at each iteration to sample within the hard likelihood constraint of nested sampling. It can identify and evolve separate modes of a posterior semi-independently and is parallelised using openMPI. PolyChord is available for download at: http://ccpforge.cse.rl.ac.uk/gf/project/polychord/
7. Preliminary Evaluation of a Nest Usage Sensor to Detect Double Nest Occupations of Laying Hens
Directory of Open Access Journals (Sweden)
Mauro Zaninelli
2015-01-01
Full Text Available Conventional cage systems will be replaced by housing systems that allow hens to move freely. These systems may improve hens’ welfare, but they lead to some disadvantages: disease, bone fractures, cannibalism, piling and lower egg production. New selection criteria for existing commercial strains should be identified considering individual data about laying performance and the behavior of hens. Many recording systems have been developed to collect these data. However, the management of double nest occupations remains critical for the correct egg-to-hen assignment. To limit such events, most systems adopt specific trap devices and additional mechanical components. Others, instead, only prevent these occurrences by narrowing the nest, without any detection and management. The aim of this study was to develop and test a nest usage “sensor”, based on imaging analysis, that is able to automatically detect a double nest occupation. Results showed that the developed sensor correctly identified the double nest occupation occurrences. Therefore, the imaging analysis resulted in being a useful solution that could simplify the nest construction for this type of recording system, allowing the collection of more precise and accurate data, since double nest occupations would be managed and the normal laying behavior of hens would not be discouraged by the presence of the trap devices.
8. Preliminary evaluation of a nest usage sensor to detect double nest occupations of laying hens.
Science.gov (United States)
Zaninelli, Mauro; Costa, Annamaria; Tangorra, Francesco Maria; Rossi, Luciana; Agazzi, Alessandro; Savoini, Giovanni
2015-01-26
Conventional cage systems will be replaced by housing systems that allow hens to move freely. These systems may improve hens' welfare, but they lead to some disadvantages: disease, bone fractures, cannibalism, piling and lower egg production. New selection criteria for existing commercial strains should be identified considering individual data about laying performance and the behavior of hens. Many recording systems have been developed to collect these data. However, the management of double nest occupations remains critical for the correct egg-to-hen assignment. To limit such events, most systems adopt specific trap devices and additional mechanical components. Others, instead, only prevent these occurrences by narrowing the nest, without any detection and management. The aim of this study was to develop and test a nest usage "sensor", based on imaging analysis, that is able to automatically detect a double nest occupation. Results showed that the developed sensor correctly identified the double nest occupation occurrences. Therefore, the imaging analysis resulted in being a useful solution that could simplify the nest construction for this type of recording system, allowing the collection of more precise and accurate data, since double nest occupations would be managed and the normal laying behavior of hens would not be discouraged by the presence of the trap devices.
9. CyNEST: a maintainable Cython-based interface for the NEST simulator
Directory of Open Access Journals (Sweden)
Yury V. Zaytsev
2014-03-01
Full Text Available NEST is a simulator for large-scale networks of spiking point neuron models (Gewaltig and Diesmann, 2007. Originally, simulations were controlled via the Simulation Language Interpreter (SLI, a built-in scripting facility implementing a language derived from PostScript (Adobe Systems, 1999. The introduction of PyNEST (Eppler et al., 2008, the Python interface for NEST, enabled users to control simulations using Python. As the majority of NEST users found PyNEST easier to use and to combine with other applications, it immediately displaced SLI as the default NEST interface.However, developing and maintaining PyNEST has become increasingly difficult over time. This is partly because adding new features requires writing low-level C++ code intermixed with calls to the Python / C API, which is unrewarding. Moreover, the Python / C API evolves with each new version of Python, which results in a proliferation of version-dependent code branches.In this contribution we present the re-implementation of PyNEST in the Cython language, a superset of Python that additionally supports the declaration of C/C++ types for variables and class attributes, and provides a convenient foreign function interface (FFI for invoking C/C++ routines (Behnel et al., 2011. Code generation via Cython allows the production of smaller and more maintainable bindings, including increased compatibility with all supported Python releases without additional burden for NEST developers. Furthermore, this novel approach opens up the possibility to support alternative implementations of the Python language at no cost given a functional Cython back-end for the corresponding implementation, and also enables cross-compilation of Python bindings for embedded systems and supercomputers alike.
10. Ants' learning of nest entrance characteristics (Hymenoptera, Formicidae).
Science.gov (United States)
Cammaerts, M C
2014-02-01
Young workers, experimentally removed from their nest and set in front of it, are not very good at finding the nest entrance and entering the nest. I examined how young ants learn their nest entrance characteristics, dealing only with the entrance sensu stricto, not with its vicinity. I observed that young ants have the innate behavior of trying to exit and re-enter their nest. I found that they are imprinted with the nest entrance odor while they are still living inside their nest and that they learn the visual aspect of their nest entrances, thanks to operant conditioning, when they exit their nest and succeed in re-entering in the course of their first short trips outside.
11. Nest sharing under semi-natural conditions in laying hens
DEFF Research Database (Denmark)
Riber, Anja Brinch
2012-01-01
problems to laying hens, and egg production may also be negatively affected. Understanding what causes this difference in nest location selection may provide solutions to the problems associated with simultaneous nest sharing. The aims were to investigate whether a commercial strain of laying hens normally...... daily of each nest with regard to number of eggs, position, and materials used. On five mornings nesting behaviour was observed. Nest sharing occurred on all but the first 5 days of egg-laying. The majority of hens (n = 14) chose to visit an occupied nest at least once, but no hens exclusively used......Under natural conditions, the feral hen (Gallus gallus domesticus) will choose a nest location away from the flock, whereas under commercial conditions, the domestic hen will often choose the same nest as other hens have used or are still using. Simultaneous nest sharing causes several welfare...
12. Crossings and nestings in colored set partitions
CERN Document Server
Marberg, Eric
2012-01-01
Several years ago, Chen, Deng, Du, Stanley, and Yan introduced the notion of $k$-crossings and $k$-nestings for set partitions, and proved that the sizes of the largest $k$-crossings and $k$-nestings in the partitions of an $n$-set possess a symmetric joint distribution. The present work extends these results to $r$-colored set partitions, by which we mean set partitions whose arcs are labeled by an $r$-element set. A $k$-crossing or $k$-nesting in this context is a sequence or arcs, all with the same color, which form a $k$-crossing or $k$-nesting in the usual sense. To prove our extension, we produce a bijection from $r$-colored set partitions to certain sequences of $r$-partite partitions, which in the uncolored case specializes to a novel description of the map from set partitions to vacillating tableaux given by Chen et al. Among other applications, we explain how our construction implies recent results of Chen and Guo on colored matchings, and also an analogous symmetric joint distribution of crossings ...
13. A Serialization Graph Construction for Nested Transactions
Science.gov (United States)
1990-02-01
allowing replacement of entire subtrees of nested activity by single actions as well as the reordering of actions in a history . Also, they do not...systems. 28 [11] N. Lynch, M. Merritt, W. Weihl, and A. Fekete. A theory of atomic transactions. In International Conference on Database Theory, Bruges
14. Collective fluid mechanics of honeybee nest ventilation
Science.gov (United States)
Gravish, Nick; Combes, Stacey; Wood, Robert J.; Peters, Jacob
2014-11-01
Honeybees thermoregulate their brood in the warm summer months by collectively fanning their wings and creating air flow through the nest. During nest ventilation workers flap their wings in close proximity in which wings continuously operate in unsteady oncoming flows (i.e. the wake of neighboring worker bees) and near the ground. The fluid mechanics of this collective aerodynamic phenomena are unstudied and may play an important role in the physiology of colony life. We have performed field and laboratory observations of the nest ventilation wing kinematics and air flow generated by individuals and groups of honeybee workers. Inspired from these field observations we describe here a robotic model system to study collective flapping wing aerodynamics. We microfabricate arrays of 1.4 cm long flapping wings and observe the air flow generated by arrays of two or more fanning robotic wings. We vary phase, frequency, and separation distance among wings and find that net output flow is enhanced when wings operate at the appropriate phase-distance relationship to catch shed vortices from neighboring wings. These results suggest that by varying position within the fanning array honeybee workers may benefit from collective aerodynamic interactions during nest ventilation.
15. Activity patterns of nesting Mexican Spotted Owls
Science.gov (United States)
David K. Delaney; Teryl G. Grubb; Paul Beier
1999-01-01
We collected 2,665 hr of behavioral information using video surveillance on 19 Mexican Spotted Owl (Strix occidentalis lucida) pairs between 25 April and 26 July 1996. Prey deliveries per day increased as the nesting season progressed, with an average of 2.68 prey deliveries during incubation, 4.10 items during brooding, and 4.51 items during the...
16. Field guide to red tree vole nests
Science.gov (United States)
Damon B. Lesmeister; James K. Swingle
2017-01-01
Surveys for red tree vole (Arborimus longicaudus) nests require tree climbing because the species is a highly specialized arboreal rodent that live in the tree canopy of coniferous forests in western Oregon and northwestern California. Tree voles are associated with old coniferous forest (â¥80 years old) that are structurally complex, but are often...
17. A catalog of Louisiana's nesting seabird colonies
Science.gov (United States)
Fontenot, William R.; Cardiff, Steve W.; DeMay, Richard A.; Dittmann, Donna L.; Hartley, Stephen B.; Jeske, Clinton W.; Lorenz, Nicole; Michot, Thomas C.; Purrington, Robert Dan; Seymour, Michael; Vermillion, William G.
2012-01-01
Summarizing his colonial nesting waterbird survey experiences along the northern coast of the Gulf of Mexico in a paper presented to the Colonial Waterbird Group of the Waterbird Society (Portnoy 1978), bird biologist John W. Portnoy stated, “This huge concentration of nesting waterbirds, restricted almost entirely to the wetlands and estuaries of southern Louisiana, is unmatched in all of North America; for example, a 1975 inventory of wading birds along the Atlantic Coast from Maine to Florida [Custer and Osborn, in press], tallied 250,000 breeding [waterbirds] of 14 species, in contrast with the 650,000 birds of 15 species just from Sabine Pass to Mobile Bay.” The “650,000 birds” to which Portnoy referred, were tallied by him in a 1976 survey of coastal Louisiana, Mississippi, and Alabama (see below, under “Major Surveys” section). According to the National Atlas of Coastal Waterbird Colonies in the Contiguous United States: 1976-82 (Spendelow and Patton 1988), the percentages of the total U.S. populations of Laughing Gull (11%), Forster's Tern (52%), Royal Tern (16%), Sandwich Tern (77%), and Black Skimmer (44%) which annually nest in Louisiana are significant – perhaps crucially so in the cases of Forster's Tern, Sandwich Tern, and Black Skimmer. Nearly three decades after Spendelow and Patton's determinations above, coastal Louisiana still stands out as the major center of colonial wading bird and seabird nesting in all of the United States. Within those three intervening decades, however, the
18. Nested Dissection Interface Reconstruction in Pececillo
Energy Technology Data Exchange (ETDEWEB)
Jibben, Zechariah Joel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-08-31
A nested dissection method for interface reconstruction in a volume tracking framework has been implemented in Pececillo. This method provides a significant improvement over the traditional onion-skin method, which does not appropriately handle T-shaped multimaterial intersections and dynamic contact lines present in additive manufacturing simulations. The resulting implementation lays the groundwork for further re- search in numerical contact angle estimates.
19. Sensitivity of Coastal Environments and Wildlife to Spilled Oil: Northwest Arctic, Alaska: NESTS (Nest Points)
Data.gov (United States)
National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for nesting birds in Northwest Arctic, Alaska. Vector points in this data set represent locations of...
20. Nesting Loggerhead Sea Turtle Activity Report 2000 and 1980-2000 Nesting Summary
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This paper presents results from the 8th Annual Study (using Army Corp of Engineers funds) of nesting by the Atlantic Loggerhead sea turtle (Caretta caretta) along...
1. Rhode Island, Connecticut, New York, and New Jersey ESI: NESTS (Nest Points)
Data.gov (United States)
National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for nesting birds in coastal Rhode Island, Connecticut, New York, and New Jersey. Vector points in this...
2. Exceptional sea turtle nest records in 2011 suggest an underestimated nesting potential in Sicily (Italy
Directory of Open Access Journals (Sweden)
Paolo Casale
2012-07-01
Full Text Available We report seven nesting events by loggerhead sea turtles in Sicily (Italy in 2011. In comparison to past records, this number is relatively high and may be at least in part due to an awareness campaign carried out in 2011 to solicit such reports. This suggests that Sicily may host a much higher nesting activity than previously thought and higher monitoring effort is recommended, especially in certain coastal tracts. Sand temperatures and incubation periods indicate that the beaches monitored so far in the southern coast are not optimal for development, resulting in low hatching success, and produce a majority of males. Five 2011 nests and two past nests from the same area had mtDNA haplotype CC-A2.1, the most common in the Mediterranean.
3. Sensitivity of Coastal Environments and Wildlife to Spilled Oil: Southern California: NESTS (Nest Points)
Data.gov (United States)
National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for nesting and roosting gulls, terns, seabirds, shorebirds, and T/E species in Southern California....
4. Timing of nest vegetation measurement may obscure adaptive significance of nest-site characteristics: A simulation study.
Science.gov (United States)
McConnell, Mark D; Monroe, Adrian P; Burger, Loren Wes; Martin, James A
2017-02-01
Advances in understanding avian nesting ecology are hindered by a prevalent lack of agreement between nest-site characteristics and fitness metrics such as nest success. We posit this is a result of inconsistent and improper timing of nest-site vegetation measurements. Therefore, we evaluated how the timing of nest vegetation measurement influences the estimated effects of vegetation structure on nest survival. We simulated phenological changes in nest-site vegetation growth over a typical nesting season and modeled how the timing of measuring that vegetation, relative to nest fate, creates bias in conclusions regarding its influence on nest survival. We modeled the bias associated with four methods of measuring nest-site vegetation: Method 1-measuring at nest initiation, Method 2-measuring at nest termination regardless of fate, Method 3-measuring at nest termination for successful nests and at estimated completion for unsuccessful nests, and Method 4-measuring at nest termination regardless of fate while also accounting for initiation date. We quantified and compared bias for each method for varying simulated effects, ranked models for each method using AIC, and calculated the proportion of simulations in which each model (measurement method) was selected as the best model. Our results indicate that the risk of drawing an erroneous or spurious conclusion was present in all methods but greater with Method 2 which is the most common method reported in the literature. Methods 1 and 3 were similarly less biased. Method 4 provided no additional value as bias was similar to Method 2 for all scenarios. While Method 1 is seldom practical to collect in the field, Method 3 is logistically practical and minimizes inherent bias. Implementation of Method 3 will facilitate estimating the effect of nest-site vegetation on survival, in the least biased way, and allow reliable conclusions to be drawn.
5. Does nest site availability limit the density of hole nesting birds in small woodland patches?
Directory of Open Access Journals (Sweden)
J. Loman
2006-11-01
Full Text Available By providing nest boxes, previous studies have shown that nest sites are in short supply and limit the populations of several small passerines, including the Great Tit Parus major, the Blue Tit P. caeruleus, and the Pied Flycatcher Ficedula hypoleuca. Can this influence their distribution over a range of small woodland patch sizes in a heterogeneous landscape? To investigate this, a study was conducted in a heterogeneous agricultural landscape, with a mixture of wooded patches and cropped fields, in southern Sweden. The descriptive part of the study involved mapping territories of the three species in 135 patches. These species avoided small (<1 ha, Pied Flycatcher or very small (<0.2 ha, the two tit species forest patches in this landscape. In an experimental part, a subset of 34 patches, 0.01 to 24 ha in size was used. Territories were mapped in a first year as a control. In a second year, patches were matched by size and vegetation and nest-boxes were provided in one patch of each pair. Territories were again mapped. Providing nestboxes increased the density of breeding Great Tits in patches of all sizes and expanded their use of very small patches. The nest-boxes increased the density of Pied Flycatchers in large patches but not in small patches. So, is the lack of territories in small patches due to shortage of nest sites? The outcome of the experiment suggests nest site limitation as a cause of the observed Great Tit discrimination against very small habitat patches. The lack of Pied Flycatchers in small patches must however have another basis than lack of nest sites. The effect of providing nest-boxes on Blue Tit distribution was inconclusive.
6. Nest site characteristics, nesting movements, and lack of long-term nest site fidelity in Agassiz's desert tortoises at a wind energy facility in southern California
Science.gov (United States)
Lovich, Jeffrey E.; Agha, Mickey; Yackulic, Charles B.; Meyer-Wilkins, Kathie; Bjurlin, Curtis; Ennen, Joshua R.; Arundel, Terry R.; Austin, Meaghan
2014-01-01
Nest site selection has important consequences for maternal and offspring survival and fitness. Females of some species return to the same nesting areas year after year. We studied nest site characteristics, fidelity, and daily pre-nesting movements in a population of Agassiz’s desert tortoises (Gopherus agassizii) at a wind energy facility in southern California during two field seasons separated by over a decade. No females returned to the same exact nest site within or between years but several nested in the same general area. However, distances between first and second clutches within a year (2000) were not significantly different from distances between nests among years (2000 and 2011) for a small sample of females, suggesting some degree of fidelity within their normal activity areas. Environmental attributes of nest sites did not differ significantly among females but did among years due largely to changes in perennial plant structure as a result of multiple fires. Daily pre-nesting distances moved by females decreased consistently from the time shelled eggs were first visible in X-radiographs until oviposition, again suggesting some degree of nest site selection. Tortoises appear to select nest sites that are within their long-term activity areas, inside the climate-moderated confines of one of their self-constructed burrows, and specifically, at a depth in the burrow that minimizes exposure of eggs and embryos to lethal incubation temperatures. Nesting in “climate-controlled” burrows and nest guarding by females relaxes some of the constraints that drive nest site selection in other oviparous species.
7. Eggshell Porosity Provides Insight on Evolution of Nesting in Dinosaurs.
Directory of Open Access Journals (Sweden)
Kohei Tanaka
Full Text Available Knowledge about the types of nests built by dinosaurs can provide insight into the evolution of nesting and reproductive behaviors among archosaurs. However, the low preservation potential of their nesting materials and nesting structures means that most information can only be gleaned indirectly through comparison with extant archosaurs. Two general nest types are recognized among living archosaurs: 1 covered nests, in which eggs are incubated while fully covered by nesting material (as in crocodylians and megapodes, and 2 open nests, in which eggs are exposed in the nest and brooded (as in most birds. Previously, dinosaur nest types had been inferred by estimating the water vapor conductance (i.e., diffusive capacity of their eggs, based on the premise that high conductance corresponds to covered nests and low conductance to open nests. However, a lack of statistical rigor and inconsistencies in this method render its application problematic and its validity questionable. As an alternative we propose a statistically rigorous approach to infer nest type based on large datasets of eggshell porosity and egg mass compiled for over 120 extant archosaur species and 29 archosaur extinct taxa/ootaxa. The presence of a strong correlation between eggshell porosity and nest type among extant archosaurs indicates that eggshell porosity can be used as a proxy for nest type, and thus discriminant analyses can help predict nest type in extinct taxa. Our results suggest that: 1 covered nests are likely the primitive condition for dinosaurs (and probably archosaurs, and 2 open nests first evolved among non-avian theropods more derived than Lourinhanosaurus and were likely widespread in non-avian maniraptorans, well before the appearance of birds. Although taphonomic evidence suggests that basal open nesters (i.e., oviraptorosaurs and troodontids were potentially the first dinosaurs to brood their clutches, they still partially buried their eggs in sediment
8. Eggshell Porosity Provides Insight on Evolution of Nesting in Dinosaurs.
Science.gov (United States)
Tanaka, Kohei; Zelenitsky, Darla K; Therrien, François
2015-01-01
Knowledge about the types of nests built by dinosaurs can provide insight into the evolution of nesting and reproductive behaviors among archosaurs. However, the low preservation potential of their nesting materials and nesting structures means that most information can only be gleaned indirectly through comparison with extant archosaurs. Two general nest types are recognized among living archosaurs: 1) covered nests, in which eggs are incubated while fully covered by nesting material (as in crocodylians and megapodes), and 2) open nests, in which eggs are exposed in the nest and brooded (as in most birds). Previously, dinosaur nest types had been inferred by estimating the water vapor conductance (i.e., diffusive capacity) of their eggs, based on the premise that high conductance corresponds to covered nests and low conductance to open nests. However, a lack of statistical rigor and inconsistencies in this method render its application problematic and its validity questionable. As an alternative we propose a statistically rigorous approach to infer nest type based on large datasets of eggshell porosity and egg mass compiled for over 120 extant archosaur species and 29 archosaur extinct taxa/ootaxa. The presence of a strong correlation between eggshell porosity and nest type among extant archosaurs indicates that eggshell porosity can be used as a proxy for nest type, and thus discriminant analyses can help predict nest type in extinct taxa. Our results suggest that: 1) covered nests are likely the primitive condition for dinosaurs (and probably archosaurs), and 2) open nests first evolved among non-avian theropods more derived than Lourinhanosaurus and were likely widespread in non-avian maniraptorans, well before the appearance of birds. Although taphonomic evidence suggests that basal open nesters (i.e., oviraptorosaurs and troodontids) were potentially the first dinosaurs to brood their clutches, they still partially buried their eggs in sediment. Open nests
9. Nest site preferences of the Woodlark (Lullula arborea) and its association with artificial nest predation
Science.gov (United States)
Buehler, Roman; Bosco, Laura; Arlettaz, Raphaël; Jacot, Alain
2017-01-01
The Woodlark is an insectivorous bird, which is listed as a priority species in Switzerland. In Valais, a stronghold of this species in the country, the birds breed in intensively managed vineyards and show a preference for parcels with ground vegetation during territory establishment. As a ground-breeder, the species is highly vulnerable to nest predation by avian and mammal predators. The aims of our study were firstly to investigate nest site preferences of the woodlark within vineyards and secondly to compare the predation risk of artificial nests dependent of ground vegetation structure. Our results point out that the Woodlark prefers patches of tall and dense ground cover within vegetated vineyard parcels and avoids parcels that have been treated with herbicides. In a follow-up experiment we conducted a study comparing the predation rate of artificial nests between bare parcels (40% vegetated area). Artificial nests equipped with one quail egg were distributed pairwise between two adjacent parcels that fulfilled the upper criteria and were monitored by trail cameras during 10-12 days. Predation rate was generally low (4 predation events) and only occurred in bare parcels. These data indicate that conspicuousness of avian nests may be decreased in vegetated parcels and that the amount of vegetation can lower the predation risk on ground breeding birds - another indication for the importance of ground vegetation for a successful conservation of the endangered Woodlark in Swiss vineyards.
10. Nesting biology of Trypoxylon (Trypargilum) lactitarse Saussure (Hymenoptera, Crabronidae) in trap-nests in Southern Brazil.
Science.gov (United States)
Buschini, M L T; Niesing, F; Wolff, L L
2006-08-01
This study was carried in the Parque Municipal das Araucárias in the municipality of Guarapuava, state of Paraná, Southern Brazil. Three hundred and sixty five nests of T. lactitarse were obtained using trap-nests of 0.7, 1.0, and 1.3 cm in diameter. All of them had similar architecture, regardless of the diameter of the trap-nest. Completed nests consisted of a linear series of brood cells whose average number per nest was of 3.3, 4.0 and 3.6 for the nests with 0.7 cm, 1.0 cm and 1.3 cm in diameter, respectively. They were constructed more often during the summer. T. lactitarse had two types of life cycles: direct development (without diapause), and delayed development (with diapause during winter). Natural enemies included Chrysididae, Sarcophagidae, Dolichopodidae and Ichneumonidae. Out of 1,353 identified spider prey, 1,313 belonged to the Araneidae family.
11. Nesting biology of Trypoxylon (Trypargilum lactitarse Saussure (Hymenoptera, Crabronidae in trap-nests in Southern Brazil
Directory of Open Access Journals (Sweden)
M. L. T. Buschini
Full Text Available This study was carried in the Parque Municipal das Araucárias in the municipality of Guarapuava, state of Paraná, Southern Brazil. Three hundred and sixty five nests of T. lactitarse were obtained using trap-nests of 0.7, 1.0, and 1.3 cm in diameter. All of them had similar architecture, regardless of the diameter of the trap-nest. Completed nests consisted of a linear series of brood cells whose average number per nest was of 3.3, 4.0 and 3.6 for the nests with 0.7 cm, 1.0 cm and 1.3 cm in diameter, respectively. They were constructed more often during the summer. T. lactitarse had two types of life cycles: direct development (without diapause, and delayed development (with diapause during winter. Natural enemies included Chrysididae, Sarcophagidae, Dolichopodidae and Ichneumonidae. Out of 1,353 identified spider prey, 1,313 belonged to the Araneidae family.
12. Nest predators, nest-site selection andnest success ofthe Emei Shan Liocichla (Liocichla omeiensis), a vulnerable babbler endemic tosouthwestern China
Institute of Scientific and Technical Information of China (English)
Yiqiang Fu; Benping Chen; Simon D Dowell; Zhengwang Zhang
2016-01-01
Background: The Emei Shan Liocichla (Liocichla omeiensis) is a globally vulnerable babbler, endemic to southwest-ern China. We investigated its nest predators, nest-site selection and nest success at the Laojunshan National Nature Reserve in Sichuan, China in order to identify the precise nesting-habitat requirements of the species, and to test whether the nest-site-selection cues, preferred by the Emei Shan Liocichla, are positively associated with nest success. Methods: We used infrared cameras to determine nest predators. We compared the microhabitat attributes between nest and random sites, as well as successful and failed nests. We used Binary Logistic Regression to determine the most important variables affecting nest-site selection of the Emei Shan Liocichla. We used the nest survival analysis in Program MARK to estimate daily nest survival rates (DSR). Nest success was calculated using the Mayifeld method. Results: In total 56 nests were found. The DSR for all nests that contained at least one egg was 0.9564± 0.0091 (95 % CI 0.9346–0.9711) (n= 40), while the total nest success was 27.5 %. We identiifed four categories of predators in 10 nest predation events, i.e. squirrels (n= 5), snakes (n= 3), raptors (n= 1) and wasps (n= 1). We found that: (1) nest predation was the primary reason for nest failure of the Emei Shan Liocichla, (2) tree cover, bamboo cover, liana abun-dance and distance to forest edge or gap were the most important variables affecting nest-site selection of this spe-cies, and (3) the nest-site-selection variables we measured appeared not to be positively associated with nest success. Conclusions: Our ifndings suggest that the Emei Shan Liocichla tended to select nest sites near forest edges or gaps with good concealment and that nest-site selection by this species was nonrandom but not necessarily adap-tive. Reducing forest-edge development and protecting bamboo stands should be effective for conservation of this species.
13. Cytosine arabinoside, vinblastine, diethylstilboestrol and 2-aminoanthracene tested in the in vitro human TK6 cell line micronucleus test (MNvit) at Institut Pasteur de Lille in support of OECD draft test guideline 487.
Science.gov (United States)
Nesslany, Fabrice; Marzin, Daniel
2010-10-29
The reference genotoxic agents Cytosine arabinoside, Vinblastine, Diethylstilboestrol and 2-Aminoanthracene were tested in the in vitro micronucleus assay, in human lymphoblastoid TK6 cells, without cytokinesis block, at the laboratories of Institut Pasteur de Lille, France. This was done in support of the toxicity measures recommended in the late 2007 version of the draft OECD Test Guideline 487 for the testing of chemicals. All four reference agents were positive in the assay at concentrations giving approximately 50% toxicity or less as assessed by draft Test Guideline 487 recommended measures, relative population doublings and relative increase in cell counts. Accordingly, this work supports the premise that relative population doublings and relative increase in cell counts are appropriate measures of toxicity for the non-cytokinesis blocked in vitro micronucleus assay.
14. Patterns of artificial nest depredation in a large floodplain forest
Science.gov (United States)
Knutson, Melinda G.; Gutreuter, Steven J.; Klaas, Erwin E.
2000-01-01
We used artificial bird nests to examine the relative effects of local habitat features and the surrounding landscape on the probability of songbird nest depredation in floodplain forests of the Upper Mississippi River. We found that the probability of depredation increased with size of floodplain forest plots. In small plots, the probability of depredation tended to increase away from the forest edge. Small patches of floodplain forest within a large river system can provide valuable nesting habitat for songbirds. We suggest that depredation pressure may be lower due to isolation effects. The probability of nest depredation increased with increasing canopy cover surrounding the nest tree and decreasing cover around the nest. Managers seeking to discourage nest predators in floodplain forests should consider managing for habitats that supply dense cover for nest concealment and an open tree canopy.
15. 2012 waterfowl nesting study at Fish Springs National Wildlife Refuge
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Report on a 2012 duck nesting study at Fish Springs National Wildlife Refuge, where nest drag plots were surveyed within management units. Duck production estimates...
16. 1972 American Eagle Nest Survey of the Chesapeake Bay Region.
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Data refers to the 1972 nesting season for the Bald Eagle in the Chesapeake area to include Virginia and Maryland. The 1972 nesting season for the Bald Eagle in the...
17. 1971 American Eagle Nest Survey of the Chesapeake Bay Region.
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Data refers to the 1971 nesting season for the Bald Eagle in the Chesapeake area to include Virginia and Maryland. In general, the Chesapeake Bay region nesting...
18. Potential Kittlitz's Murrelet Nesting Habitat in North America
Data.gov (United States)
U.S. Geological Survey, Department of the Interior — Using nest records and locations to identify landscape-scale parameters (distance to coast, elevation, slope, and land cover) that provide potential nesting habitat,...
19. DISPERSAL OF SEEDS AS NEST MATERIAL BY THE CACTUS WREN
Science.gov (United States)
Cactus wren (Campylorhynchus brunneicapillus) nests from the southern Chihuahuan Desert contained viable seeds of grasses, forbs, and shrubs. The most common plants used as construction material in these nests were Muhlenbergia porteri, Boerhavia spicata, and the alien grass Era...
20. Seedskadee National Wildlife Refuge : duck nesting success report
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This is a report summarizing the fourth consecutive year of data collection for duck nesting success at Seedskadee National Wildlife Refuge during the 1990 nesting...
1. Nest sites selection by sympatric cavity-nesting birds in miombo woodlands
Directory of Open Access Journals (Sweden)
Vincent R. Nyirenda
2016-03-01
Full Text Available Deforestation and habitat fragmentation have long been known as drivers of wildlife depletion but information on their specific impacts on cavity-nesting birds in the miombo woodlands has been lacking. A comparative study of disturbed and undisturbed sites was conducted in miombo woodlands of Zambia to assess impacts of environmental stressors on birds. Foot patrols were employed to locate, identify and count host trees and cavities for cavity-nesting birds on twenty 200 m × 200 m sample plots. Undisturbed forests had three times more cavities (the nesting sites for birds, while there were 24.6% fewer abandoned cavities in undisturbed forests than in disturbed forests. The rate of cavity abandonment was about twice as high in human-dominated forests compared to undisturbed forests (61.3% c.f. 31.9%. Cavity-nesting birds preferred larger (> 36.0 cm diameter at breast height and taller (> 5.0 m trees for nest placement, especially in human-dominated forests. A number of cavity-nesting birds preferred Brachystegia spiciformis (zebrawood, Julbernadia paniculata (munsa, Parinari curatellifolia (mobola-plum and Uapaca kirkiana (mahobohobo as host trees to 14 other miombo tree species. Arnot’s Chat (Myrmecocichla arnoti had a wider selection of host trees for cavity-nesting than the other 40 cavity-nesting birds in the study areas. Anthropogenic activities such as uncontrolled firewood collection, wild fires, logging, and land clearing for agriculture negatively influenced wood abundance and diversity, with potential implications for persistence of cavity-nesting birds. The negative impacts of anthropogenic activities could be counteracted by conservation strategies such as implementation of sound forest policies, integrative land use practices, sustainable livelihood security and stakeholders’ awareness of the need to safeguard forest-dependent avifauna.Conservation implications: This comparative study unravels specific anthropogenic impacts on
2. Nesting biology of four Tetrapedia species in trap-nests (Hymenoptera: Apidae: Tetrapediini).
Science.gov (United States)
Camillo, Evandro
2005-01-01
The nests used in this study were obtained from trap-nests (tubes of cardboard and cut bamboo stems) placed on Santa Carlota Farm (Itaoca Section-IS, Santana Section-SS and Cerrado-Ce), Cajuru, SP, Brazil. The number of nests and corresponding species obtained were as follows: 516 nests of T. curvitarsis, 104 of T. rugulosa, 399 of T. diversipes and 98 of T. gamfaloi. The most abundant species from SS and Ce was T. curvitarsis, and from IS it was T. diversipes. In general, most nests were collected during the hot and wet season (September to April). The nests were constructed with sand and an oily substance, and a single female established them. The cells were constructed in a linear series, sometimes followed by a vestibular cell. The number of brood cells ranged from 1 to 10 in T. curvitarsis (n=200), and in T. garofaloi (n-51), from 1 to 8 (n-30) in T. rugulosa, and from 1 to 6 (n=37) in T. diversipes. The pollen mass (pollen + oily substance) contained a hollow, sometimes divided by a transverse ridge, on the exposed face of the pollen mass. The egg was vertically positioned in the lower part of the hollow. At times, the closing of a cell was initiated before provisioning was completed, with a construction of a collar at the cell limit. In some nests the final cellular partition also acted as a closure plug. Females began activities at 6:18 a.m. and ended between 3:31 and 6:26 p.m. Some females (T. curvitarsis, T. rugiulosa and T. ganrfaloi) did not spend the nights at their nests, returning to them only the following morning with additional material. In general, the development period (for males and females) was greater in nests collected near the end of the hot and wet season than it was for nests collected in other months. Sex ratios for each species were as follows: T. curvitarsis. 1:1: T. rugulosa, 1.6:1 female; T. diversipes, 1.9:1: T. garofaloi, 2.8:1. Males and females of T. diversipes exhibited statistically similar sizes and in the other three species
3. Comparing coefficients of nested nonlinear probability models
DEFF Research Database (Denmark)
Kohler, Ulrich; Karlson, Kristian Bernt; Holm, Anders
2011-01-01
In a series of recent articles, Karlson, Holm and Breen have developed a method for comparing the estimated coeffcients of two nested nonlinear probability models. This article describes this method and the user-written program khb that implements the method. The KHB-method is a general decomposi......In a series of recent articles, Karlson, Holm and Breen have developed a method for comparing the estimated coeffcients of two nested nonlinear probability models. This article describes this method and the user-written program khb that implements the method. The KHB-method is a general...... decomposition method that is unaffected by the rescaling or attenuation bias that arise in cross-model comparisons in nonlinear models. It recovers the degree to which a control variable, Z, mediates or explains the relationship between X and a latent outcome variable, Y*, underlying the nonlinear probability...
4. Broadband DOA Estimation Based on Nested Arrays
Directory of Open Access Journals (Sweden)
Zhi-bo Shen
2015-01-01
Full Text Available Direction of arrival (DOA estimation is a crucial problem in electronic reconnaissance. A novel broadband DOA estimation method utilizing nested arrays is devised in this paper, which is capable of estimating the frequencies and DOAs of multiple narrowband signals in broadbands, even though they may have different carrier frequencies. The proposed method converts the DOA estimation of multiple signals with different frequencies into the spatial frequency estimation. Then, the DOAs and frequencies are pair matched by sparse recovery. It is possible to significantly increase the degrees of freedom (DOF with the nested arrays and the number of sources can be more than that of sensor array. In addition, the method can achieve high estimation precision without the two-dimensional search process in frequency and angle domain. The validity of the proposed method is verified by theoretic analysis and simulation results.
5. Nested partitions method, theory and applications
CERN Document Server
Shi, Leyuan
2009-01-01
There is increasing need to solve large-scale complex optimization problems in a wide variety of science and engineering applications, including designing telecommunication networks for multimedia transmission, planning and scheduling problems in manufacturing and military operations, or designing nanoscale devices and systems. Advances in technology and information systems have made such optimization problems more and more complicated in terms of size and uncertainty. Nested Partitions Method, Theory and Applications provides a cutting-edge research tool to use for large-scale, complex systems optimization. The Nested Partitions (NP) framework is an innovative mix of traditional optimization methodology and probabilistic assumptions. An important feature of the NP framework is that it combines many well-known optimization techniques, including dynamic programming, mixed integer programming, genetic algorithms and tabu search, while also integrating many problem-specific local search heuristics. The book uses...
6. Recursive Polynomial Remainder Sequence and the Nested Subresultants
OpenAIRE
Terui, Akira
2008-01-01
We give two new expressions of subresultants, nested subresultant and reduced nested subresultant, for the recursive polynomial remainder sequence (PRS) which has been introduced by the author. The reduced nested subresultant reduces the size of the subresultant matrix drastically compared with the recursive subresultant proposed by the authors before, hence it is much more useful for investigation of the recursive PRS. Finally, we discuss usage of the reduced nested subresultant in approxima...
7. Imperfect nesting in unconventional density waves
Science.gov (United States)
Dóra, Balázs; Virosztek, Attila; Maki, Kazumi
2002-03-01
Recently, we have shown that unconventional charge density wave (UCDW) is the most likely candidate for the unidentified low-temperature phase (LTP) in α-(ET)2 salts. In particular, UCDW describes reasonably well the temperature dependence of the threshold electric field of LTP in α-(ET)2KHg(SCN)4. Here, we shall show that the imperfect nesting in UCDW is crucial to further improve the theoretical description of the threshold electric field.
8. Structural relations between nested harmonic sums
Energy Technology Data Exchange (ETDEWEB)
Bluemlein, J.
2008-07-15
We describe the structural relations between nested harmonic sums emerging in the description of physical single scale quantities up to the 3-loop level in renormalizable gauge field theories. These are weight w=6 harmonic sums. We identify universal basic functions which allow to describe a large class of physical quantities and derive their complex analysis. For the 3-loop QCD Wilson coefficients 35 basic functions are required, whereas a subset of 15 describes the 3-loop anomalous dimensions. (orig.)
9. Nested Dissection Interface Reconstruction in Pececillo
Energy Technology Data Exchange (ETDEWEB)
Jibben, Zechariah Joel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division; Carlson, Neil N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division; Francois, Marianne M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division
2016-09-13
A nested dissection method for interface reconstruction in a volume tracking framework has been implemented in Pececillo, a mini-app for Truchas, which is the ASC code for casting and additive manufacturing. This method provides a significant improvement over the traditional onion-skin method, which does not appropriately handle T-shaped multimaterial intersections and dynamic contact lines present in additive manufacturing simulations. The resulting implementation lays the groundwork for further research in contact angle estimates and surface tension calculations.
10. DIAMONDS: a new Bayesian nested sampling tool*
Directory of Open Access Journals (Sweden)
Corsaro Enrico
2015-01-01
Full Text Available In the context of high-quality asteroseismic data provided by the NASA Kepler Mission, we developed a new code, termed DIAMONDS (high-DImensional And multi-MOdal NesteD Sampling, for fast Bayesian parameter estimation and model comparison by means of the Nested Sampling Monte Carlo (NSMC algorithm, an efficient and powerful method very suitable for high-dimensional problems (like the peak bagging analysis of solar-like oscillations and multi-modal problems (i.e. problems that show multiple solutions. We applied the code to the peak bagging analysis of solar-like oscillations observed in a challenging F-type star. By means of DIAMONDS one is able to detect the different backgrounds in the power spectrum of the star (e.g. stellar granulation and faculae activity and to understand whether one or two oscillation peaks can be identified or not. In addition, we demonstrate a novel approach to peak bagging based on multi-modality, which is able to reduce significantly the number of free parameters involved in the peak bagging model. This novel approach is therefore of great interest for possible future automatization of the entire analysis technique.
11. Effects of prescribed burns on wintering cavity-nesting birds
Science.gov (United States)
Heather L. Bateman; Margaret A. O' Connell
2006-01-01
Primary cavity-nesting birds play a critical role in forest ecosystems by excavating cavities later used by other birds and mammals as nesting or roosting sites. Several species of cavity-nesting birds are non-migratory residents and consequently subject to winter conditions. We conducted winter bird counts from 1998 to 2000 to examine the abundance and habitat...
12. Nest Success of Gunnison Sage-Grouse in Colorado, USA.
Directory of Open Access Journals (Sweden)
Amy J Davis
Full Text Available Gunnison Sage-Grouse (Centrocercus minimus is a species of concern for which little demographic information exists. To help fill this information gap, we investigated factors affecting nest success in two populations of Gunnison Sage-Grouse. We assessed the relative effects of (1 vegetation characteristics (e.g., shrub height, shrub cover, grass cover, and grass height, (2 temporal factors (e.g., year, timing of incubation initiation, and nest age, (3 precipitation, and (4 age of the nesting female (yearling or adult on nest success rates. We found 177 nests in the Gunnison Basin population (that contains 85-90% of the species from 2005-2010 and 20 nests in the San Miguel population (that contains < 10% of the species from 2007-2010. Temporal factors had the greatest impact on nest success compared to vegetation characteristics, precipitation, and female age. Nest success varied considerably among years ranging from 4.0%-60.2% in Gunnison Basin and from 12.9%- 51.9% in San Miguel. Nests that were initiated earlier in the breeding season had higher nest success (at least one egg hatches. Daily nest survival rates decreased during the course of incubation. None of the vegetation characteristics we examined were strongly related to nest success.
13. Ant colonies prefer infected over uninfected nest sites
DEFF Research Database (Denmark)
Pontieri, Luigi; Vojvodic, Svjetlana; Graham, Riley
2014-01-01
the high risk of epidemics in group-living animals. Choosing nest sites free of pathogens is hypothesized to be highly efficient in invasive ants as each of their introduced populations is often an open network of nests exchanging individuals (unicolonial) with frequent relocation into new nest sites...
14. Communal nesting and kinship in degus (Octodon degus)
Science.gov (United States)
Ebensperger, Luis A.; Hurtado, María José; Soto-Gamboa, Mauricio; Lacey, Eileen A.; Chang, Ann T.
Communal nesting is a fundamental component of many animal societies. Because the fitness consequences of this behavior vary with the relatedness among nest mates, understanding the kin structure of communally nesting groups is critical to understanding why such groups form. Observations of captive degus (Octodon degus) indicate that multiple females nest together, even when supplied with several nest boxes. To determine whether free-living degus also engage in communal nesting, we used radiotelemetry to monitor spatial relationships among adult females in a population of O. degus in central Chile. These analyses revealed that females formed stable associations of > 2-4 individuals, all of whom shared the same nest site at night. During the daytime, spatial overlap and frequency of social interactions were greatest among co-nesting females, suggesting that nesting associations represent distinct social units. To assess kinship among co-nesting females, we examined genotypic variation in our study animals at six microsatellite loci. These analyses indicated that mean pairwise relatedness among members of a nesting association (r=0.25) was significantly greater than that among randomly selected females (r=-0.03). Thus, communally nesting groups of degus are composed of female kin, making it possible for indirect as well as direct fitness benefits to contribute to sociality in this species.
15. Trap-nests for stingless bees (Hymenoptera, Meliponini)
NARCIS (Netherlands)
Oliveira, Ricardo Caliari; Menezes, Cristiano; Egea Soares, Ademilson Espencer; Imperatriz Fonseca, Vera Lucia
2013-01-01
Most stingless bee species build their nests inside tree hollows. In this paper, we present trap-nest containers which simulate nesting cavities so as to attract swarms of stingless bees. Although regularly used by stingless bee beekeepers in Brazil, this technique to obtain new colonies has not yet
16. Semantic Analysis of Virtual Classes and Nested Classes
DEFF Research Database (Denmark)
1999-01-01
Virtual classes and nested classes are distinguishing features of BETA. Nested classes originated from Simula, but until recently they have not been part of main stream object- oriented languages. C++ has a restricted form of nested classes and they were included in Java 1.1. Virtual classes...... the central elements of the semantic analysis used in the Mjølner BETA compiler....
17. A Local Characterization of Lie Homomorphisms of Nest Algebras
Institute of Scientific and Technical Information of China (English)
YANG Miao-xia; ZHANG Jian-hua
2014-01-01
In this paper, linear maps preserving Lie products at zero points on nest algebras are studied. It is proved that every linear map preserving Lie products at zero points on any finite nest algebra is a Lie homomorphism. As an application, the form of a linear bijection preserving Lie products at zero points between two finite nest algebras is obtained.
18. An Architecture for Nested Transaction Support on Standard Database Systems
NARCIS (Netherlands)
Boertjes, E.M.; Grefen, P.W.P.J.; Vonk, J.; Apers, Peter M.G.
Many applications dealing with complex processes require database support for nested transactions. Current commercial database systems lack this kind of support, offering flat, non-nested transactions only. This paper presents a three-layer architecture for implementing nested transaction support on
19. Ground nesting in recultivated forest habitats - a study with artificial nests
Energy Technology Data Exchange (ETDEWEB)
Purger, J.J.; Meszaros, L.A.; Purger, D. [University of Pecs, Pecs (Hungary). Faculty of Science
2004-01-01
The study was carried out in the outskirts of the town of Pecs (southern Hungary) in a recultivated former coal mine. Bordered by Turkey Oak forests, this open area forms a wedge-shaped clearing in that woodland. Since trees and taller shrubs are rare in the area, it is mainly ground nesting bird species that occur in the clearing. In order to discover whether it is more advantageous to nest in the recultivated area (clearing) than in the nearby forest or at its edges, 150 artificial ground nests were constructed. On 7 May 2002, one quail egg and a plasticine egg of similar size were placed in each of the artificial nests. After a week it was found that 24% of nests in the clearing, 30% of those in the forest edge, and 44% of the ones inside the forest had suffered depredation. The proportions of damaged plasticine and quail eggs inside the forest and at the forest edge were similar, whereas the quail eggs in the clearings were significantly less damaged than plasticine eggs. Of all the experimental eggs, significantly more plasticine eggs (29%) were damaged than quail eggs (17%), which suggests that small-bodied predators are unable to break the quail eggs. 18% of the plasticine eggs attacked, and 72% of the quail eggs attacked were removed from the nest by the predator. Among the predators, small mammals were dominant in the clearing and inside the forest, and birds at the forest edge. Based on the predation of quail eggs, the survival chances of ground nests in the clearing are greater than at the forest edge or inside the forest.
20. Changes in position and quality of preferred nest box: effects on nest box use by laying hens
DEFF Research Database (Denmark)
Riber, Anja Brinch; Nielsen, Birte L.
2013-01-01
Using laying hens, we investigated whether position of a nest box, both within the pen and relative to other nest boxes, influenced the preference for a nest box, and how a sudden and marked change to the preferred box influenced the use of nest boxes by the hens. Groups (n=12) of 15 Isa Warren...... revealed that some hens were location conservative, i.e. continued laying in a corner location (or as close to that as possible), whereas others were isolation conservative, i.e. continued laying in the most isolated nest box despite it being positioned in a different area of the pen....... hens were housed in pens, each with five identical nest boxes in different positions: Two single (in a corner or not) and a triplet of nest boxes (one of which in a corner). The use of nest boxes was determined by the number of eggs laid daily in each box. Three experiments, each lasting 10 days, were...
1. Sharp-Tailed Grouse Nest Survival and Nest Predator Habitat Use in North Dakota’s Bakken Oil Field
Science.gov (United States)
2017-01-01
Recent advancements in extraction technologies have resulted in rapid increases of gas and oil development across the United States and specifically in western North Dakota. This expansion of energy development has unknown influences on local wildlife populations and the ecological interactions within and among species. Our objectives for this study were to evaluate nest success and nest predator dynamics of sharp-tailed grouse (Tympanuchus phasianellus) in two study sites that represented areas of high and low energy development intensities in North Dakota. During the summers of 2012 and 2013, we monitored 163 grouse nests using radio telemetry. Of these, 90 nests also were monitored using miniature cameras to accurately determine nest fates and identify nest predators. We simultaneously conducted predator surveys using camera scent stations and occupancy modeling to estimate nest predator occurrence at each site. American badgers (Taxidea taxus) and striped skunks (Mephitis mephitis) were the primary nest predators, accounting for 56.7% of all video recorded nest depredations. Nests in our high intensity gas and oil area were 1.95 times more likely to succeed compared to our minimal intensity area. Camera monitored nests were 2.03 times more likely to succeed than non-camera monitored nests. Occupancy of mammalian nest predators was 6.9 times more likely in our study area of minimal gas and oil intensity compared to the high intensity area. Although only a correlative study, our results suggest energy development may alter the predator community, thereby increasing nest success for sharp-tailed grouse in areas of intense development, while adjacent areas may have increased predator occurrence and reduced nest success. Our study illustrates the potential influences of energy development on the nest predator—prey dynamics of sharp-tailed grouse in western North Dakota and the complexity of evaluating such impacts on wildlife. PMID:28081245
2. Nest-site competition between invasive and native cavity nesting birds and its implication for conservation.
Science.gov (United States)
Charter, Motti; Izhaki, Ido; Ben Mocha, Yitzchak; Kark, Salit
2016-10-01
Nesting cavities are often a limited resource that multiple species use. There is an ongoing discussion on whether invasive cavity nesting birds restrict the availability of this key limited resource. While the answer to this question has important conservation implications, little experimental work has been done to examine it. Here, we aimed to experimentally test whether alien cavity nesting birds affect the occupancy of cavities and the resulting breeding success of native cavity breeders in a large urban park located in Tel Aviv, Israel. Over three breeding seasons, we manipulated the entry size of nest boxes and compared the occupancy and breeding success of birds in nest boxes of two treatments. These included nest boxes with large-entrance and small-entrance holes. The large-entrance holes allowed access for both the native and invasive birds (the two main aliens in the park are the common mynas and rose-ringed parakeets). The smaller-entrance boxes, on the other hand, allowed only the smaller sized native cavity breeders (great tits and house sparrows) to enter the boxes but prevented the alien species from entering. We found that the large-entrance nest boxes were occupied by five different bird species, comprising three natives (great tit, house sparrow, Scops owl) and two invasive species (common myna, rose-ringed parakeet) while the small-entrance boxes were only occupied by the two native species. The alien common mynas and rose-ringed parakeets occupied 77.5% of the large-entrance nest boxes whereas native species, mainly great tits, occupied less than 9% of the large-entrance boxes and 36.5% of the small-entrance boxes. When examining the occupancy of those cavities that were not occupied by the aliens, natives occupied both the small and large-entrance nest boxes equally. Three quarters (78%) of the great tits breeding in the large-entrance boxes were usurped by common mynas during the breeding season and as a result breeding success was
3. Effects of Nest Spacing on Nest Occupation, Mating Success and Mating Behaviour in the Two-spotted Goby (Gobiusculus flavescens)
OpenAIRE
2011-01-01
I investigated hoe different spacing of breeding sited affects different aspects of mating behaviour in the two-spotted goby. I found that clumped nest spacing affects nest occupations and reproductive success negatively. Clumped nest spacing incresed male agonistic behaviour and led to a higher variance in reproductive success.
4. EFL Students' and Teachers' Attitudes toward Foreign Language Speaking Anxiety: A Look at NESTs and Non-NESTs
Science.gov (United States)
Han, Turgay; Tanriöver, Ahmet Serkan; Sahan, Özgür
2016-01-01
Native English Speaking Teachers (NESTs) have been employed in various English language teaching (ELT) positions and departments at private and state universities in Turkey, particularly over the last three decades. However, undergraduate EFL students' attitudes toward NESTs and Non-Native English Speaking Teachers (Non-NESTs) remain seriously…
5. Ant colonies prefer infected over uninfected nest sites
DEFF Research Database (Denmark)
Pontieri, Luigi; Vojvodic, Svjetlana; Graham, Riley;
2014-01-01
During colony relocation, the selection of a new nest involves exploration and assessment of potential sites followed by colony movement on the basis of a collective decision making process. Hygiene and pathogen load of the potential nest sites are factors worker scouts might evaluate, given...... and low genetic diversity, likely making these species particularly vulnerable to parasites and diseases. We investigated the nest site preference of the invasive pharaoh ant, Monomorium pharaonis, through binary choice tests between three nest types: nests containing dead nestmates overgrown...
6. Estimating raptor nesting success: old and new approaches
Science.gov (United States)
Brown, Jessi L.; Steenhof, Karen; Kochert, Michael N.; Bond, Laura
2013-01-01
Studies of nesting success can be valuable in assessing the status of raptor populations, but differing monitoring protocols can present unique challenges when comparing populations of different species across time or geographic areas. We used large datasets from long-term studies of 3 raptor species to compare estimates of apparent nest success (ANS, the ratio of successful to total number of nesting attempts), Mayfield nesting success, and the logistic-exposure model of nest survival. Golden eagles (Aquila chrysaetos), prairie falcons (Falco mexicanus), and American kestrels (F. sparverius) differ in their breeding biology and the methods often used to monitor their reproduction. Mayfield and logistic-exposure models generated similar estimates of nesting success with similar levels of precision. Apparent nest success overestimated nesting success and was particularly sensitive to inclusion of nesting attempts discovered late in the nesting season. Thus, the ANS estimator is inappropriate when exact point estimates are required, especially when most raptor pairs cannot be located before or soon after laying eggs. However, ANS may be sufficient to assess long-term trends of species in which nesting attempts are highly detectable.
7. Resource redistribution in polydomous ant nest networks: local or global?
Science.gov (United States)
Franks, Daniel W.; Robinson, Elva J.H.
2014-01-01
An important problem facing organisms in a heterogeneous environment is how to redistribute resources to where they are required. This is particularly complex in social insect societies as resources have to be moved both from the environment into the nest and between individuals within the nest. Polydomous ant colonies are split between multiple spatially separated, but socially connected, nests. Whether, and how, resources are redistributed between nests in polydomous colonies is unknown. We analyzed the nest networks of the facultatively polydomous wood ant Formica lugubris. Our results indicate that resource redistribution in polydomous F. lugubris colonies is organized at the local level between neighboring nests and not at the colony level. We found that internest trails connecting nests that differed more in their amount of foraging were stronger than trails between nests with more equal foraging activity. This indicates that resources are being exchanged directly from nests with a foraging excess to nests that require resources. In contrast, we found no significant relationships between nest properties, such as size and amount of foraging, and network measures such as centrality and connectedness. This indicates an absence of a colony-level resource exchange. This is a clear example of a complex behavior emerging as a result of local interactions between parts of a system. PMID:25214755
8. Desmoplastic nested spindle cell tumours and nested stromal epithelial tumours of the liver.
Science.gov (United States)
Misra, Sunayana; Bihari, Chhagan
2016-04-01
Desmoplastic nested spindle cell tumour of liver (DNSTL), nested stromal-epithelial tumour (NSET) and calcifying nested stromal-epithelial tumour (CNSET) are recently described entities with similar morphology, immunohistochemistry and molecular genetics. These are rare entities with only three large case series described till date. These tumours commonly present in the paediatric age group. NSETs, in addition have been described to be associated with ectopic adrenocorticotropic hormone (ACTH) production and Cushingoid features. It is important to discuss this rare group of tumours with a low malignant potential as the most common radiological differential diagnosis is hepatoblastoma, which has a relatively poorer prognosis. Thus, a pathologist needs to keep this entity in mind, so as to offer a correct histological diagnosis.
9. Grassland birds orient nests relative to nearby vegetation
Science.gov (United States)
Hoekman, S.T.; Ball, I.J.; Fondell, T.E.
2002-01-01
We studied orientation of nest sites relative to nearby vegetation for dabbling ducks (Cinnamon Teal, Anas cyanoptera; Blue-winged Teal, A. discors; Gadwall, A. strepera; Mallard, A. platyrhynchos; and Northern Shoveler, A. clypeata) and Short-eared Owls (Asio flammeus) in ungrazed grassland habitat during 1995-1997 in westcentral Montana. We estimated an index of vegetation height and density in intercardinal directions (NE, SE, SW, NW) immediately around nests. All species oriented nests with the least vegetation to the southeast and the most vegetation to either the southwest or northwest. Furthermore, maximum vegetation around nests shifted from the southwest to the northwest with increasing nest initiation date, apparently as a response of individuals tracking seasonal change in the afternoon solar path. Thus, nests were relatively exposed to solar insolation during cool morning hours but were shaded from intense insolation in the afternoon throughout the breeding season. We suggest that nest microhabitat was selected in part to moderate the thermal environment.
10. Blackbeard Island National Wildlife Refuge Loggerhead Sea Turtle Nest Monitoring: End of Season Report - 2013
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — The 2013 Loggerhead sea turtle nesting season resulted in 284 nests with 17,915 emerged hatchlings. Of the 284 nests, 162 (57%) remained in situ with 122 (43%) nests...
11. Nest-site selection and nest success of an Arctic-breeding passerine, Smith's Longspur, in a changing climate
Science.gov (United States)
McFarland, Heather R.; Kendall, Steve J.; Powell, Abby
2017-01-01
Despite changes in shrub cover and weather patterns associated with climate change in the Arctic, little is known about the breeding requirements of most passerines tied to northern regions. We investigated the nesting biology and nest habitat characteristics of Smith's Longspurs (Calcarius pictus) in 2 study areas in the Brooks Range of Alaska, USA. First, we examined variation in nesting phenology in relation to local temperatures. We then characterized nesting habitat and analyzed nest-site selection for a subset of nests (n = 86) in comparison with paired random points. Finally, we estimated the daily survival rate of 257 nests found in 2007–2013 with respect to both habitat characteristics and weather variables. Nest initiation was delayed in years with snow events, heavy rain, and freezing temperatures early in the breeding season. Nests were typically found in open, low-shrub tundra, and never among tall shrubs (mean shrub height at nests = 26.8 ± 6.7 cm). We observed weak nest-site selection patterns. Considering the similarity between nest sites and paired random points, coupled with the unique social mating system of Smith's Longspurs, we suggest that habitat selection may occur at the neighborhood scale and not at the nest-site scale. The best approximating model explaining nest survival suggested a positive relationship with the numbers of days above 21°C that an individual nest experienced; there was little support for models containing habitat variables. The daily nest survival rate was high (0.972–0.982) compared with that of most passerines in forested or grassland habitats, but similar to that of passerines nesting on tundra. Considering their high nesting success and ability to delay nest initiation during inclement weather, Smith's Longspurs may be resilient to predicted changes in weather regimes on the breeding grounds. Thus, the greatest threat to breeding Smith's Longspurs associated with climate change may be the loss of low
12. Island characteristics within wetlands influence waterbird nest success and abundance
Science.gov (United States)
Hartman, Christopher; Ackerman, Josh; Herzog, Mark
2016-01-01
Coastal waterbird populations are threatened by habitat loss and degradation from urban and agricultural development and forecasted sea level rise associated with climate change. Remaining wetlands often must be managed to ensure that waterbird habitat needs, and other ecosystem functions, are met. For many waterbirds, the availability of island nesting habitat is important for conserving breeding populations. We used linear mixed models to investigate the influence of pond and island landscape characteristics on nest abundance and nest success of American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), and Forster's terns (Sterna forsteri) in San Francisco Bay, California, USA, based on a 9-year dataset that included >9,000 nests. Nest abundance and nest success were greatest within ponds and on individual islands located either 4 km from San Francisco Bay. Further, nest abundance was greater within ponds with relatively few islands, and on linear-shaped, highly elongated islands compared to more rounded islands. Nest success was greater on islands located away from the nearest surrounding pond levee. Compared to more rounded islands, linear islands contained more near-water habitat preferred by many nesting waterbirds. Islands located away from pond levees may provide greater protection from terrestrial egg and chick predators. Our results indicate that creating and maintaining a few, relatively small, highly elongated and narrow islands away from mainland levees, in as many wetland ponds as possible would be effective at providing waterbirds with preferred nesting habitat.
13. Does cooperation mean kinship between spatially discrete ant nests?
Science.gov (United States)
Procter, Duncan S; Cottrell, Joan E; Watts, Kevin; A'Hara, Stuart W; Hofreiter, Michael; Robinson, Elva J H
2016-12-01
Eusociality is one of the most complex forms of social organization, characterized by cooperative and reproductive units termed colonies. Altruistic behavior of workers within colonies is explained by inclusive fitness, with indirect fitness benefits accrued by helping kin. Members of a social insect colony are expected to be more closely related to one another than they are to other conspecifics. In many social insects, the colony can extend to multiple socially connected but spatially separate nests (polydomy). Social connections, such as trails between nests, promote cooperation and resource exchange, and we predict that workers from socially connected nests will have higher internest relatedness than those from socially unconnected, and noncooperating, nests. We measure social connections, resource exchange, and internest genetic relatedness in the polydomous wood ant Formica lugubris to test whether (1) socially connected but spatially separate nests cooperate, and (2) high internest relatedness is the underlying driver of this cooperation. Our results show that socially connected nests exhibit movement of workers and resources, which suggests they do cooperate, whereas unconnected nests do not. However, we find no difference in internest genetic relatedness between socially connected and unconnected nest pairs, both show high kinship. Our results suggest that neighboring pairs of connected nests show a social and cooperative distinction, but no genetic distinction. We hypothesize that the loss of a social connection may initiate ecological divergence within colonies. Genetic divergence between neighboring nests may build up only later, as a consequence rather than a cause of colony separation.
14. Experimental nest site limitation affects reproductive strategies and parental investment in a hole-nesting passerine
NARCIS (Netherlands)
Jacot, A.; Valcu, M.; Van Oers, K.; Kempenaers, B.
2009-01-01
In resource defence mating systems, males monopolize a resource that is of primary importance for breeding females. For secondary cavity nesters, the availability of suitable nesting sites is important in determining the strength of intrasexual competition, whereby phenotypic and behavioural traits
15. Flexibility in nest-site choice and nesting success of Turdus rufiventris (Turdidae) in a montane forest in northwestern argentina
Science.gov (United States)
Lomascolo, S.B.; Monmany, A.C.; Malizia, A.; Martin, T.E.
2010-01-01
We studied the consequences of nest-site choice on nesting success under differing disturbance levels for the Rufous-bellied Thrush (Turdus rufiventris). We compared nest-site choice and nest success between a disturbed site and an undisturbed site in a montane subtropical forest in northwestern Argentina. We found no overall difference in daily predation rate (DPR) between the disturbed and undisturbed sites. However, DPR of nests on bromeliads was significantly lower at the microhabitat level than on other types of subtrates at the disturbed site. T. rufiventris used bromeliads for nesting more often than expected by chance at the disturbed site. DPR did not differ between substrates at the undisturbed site and T. rufiventris used all substrates according to their availability. Nests had higher predation at the disturbed site when DPR on non-bromeliad substrates was compared between disturbed and undisturbed sites. Nest fate was independent of nest height. Our results suggest T. rufiventris' flexibility in nest-site choice, as reflected by increased use of the safest sites, i.e., bromeliads, in the disturbed site compared to the undisturbed site, may allow this species to survive in an otherwise much riskier habitat. Our results illustrate how microhabitat-scale effects can mediate landscape scale effects. ?? 2010 by the Wilson Ornithological Society.
16. Nests with numerous SOX10 and MiTF-positive cells in lichenoid inflammation: pseudomelanocytic nests or authentic melanocytic proliferation?
Science.gov (United States)
Silva, Claudine Yap; Goldberg, Lynne J; Mahalingam, Meera; Bhawan, Jag; Wolpowitz, Deon
2011-10-01
Pseudomelanocytic nests in the setting of lichenoid inflammation can mimic atypical melanocytic proliferations. Both melanocytic and cytokeratin immunohistochemical stains may be utilized to differentiate these entities. Unlike true melanocytic nests, pseudomelanocytic nests contain Melanoma Antigen Recognized by T-cells 1 (MART-1)/ Melan-A-positive cells and cells positive for pan-cytokeratins, CD3 and/or CD68. Recently, rare (1-2 cells/nest) microphthalmia- associated transcription factor (MiTF)-positive cells were also reported in pseudomelanocytic nests. We present a 48-year-old man with a 2 × 3 cm violaceous to hyperpigmented, non-blanching, polygonal patch on the neck. Histopathology showed focal epidermal atrophy, irregularly distributed junctional nests and a lichenoid infiltrate with colloid bodies. Immunoperoxidase studies revealed occasional pan-cytokeratin and MART-1/Melan-A-positive staining in nests as well as focal S-100 protein-positive cells. Importantly, the majority of nests showed numerous cells positive for MiTF and SOX10 (>2 cells/nest and some the majority of cells). This combined staining pattern confounds the above-described immunohistochemical distinction between pseudo and true melanocytic nests. Clinically felt to represent unilateral lichen planus pigmentosus/erythema dyschromicum perstans and not malignant melanoma in situ, this lesion highlights the importance of clinicopathologic correlation and suggests either a new melanocytic entity or a novel pattern of benign melanocytic reorganization in a subset of lichenoid dermatitides.
17. Characteristic Formulae for Relations with Nested Fixed Points
Directory of Open Access Journals (Sweden)
Luca Aceto
2012-02-01
Full Text Available A general framework for the connection between characteristic formulae and behavioral semantics is described in [2]. This approach does not suitably cover semantics defined by nested fixed points, such as the n-nested simulation semantics for n greater than 2. In this study we address this deficiency and give a description of nested fixed points that extends the approach for single fixed points in an intuitive and comprehensive way.
18. Sandhill crane abundance and nesting ecology at Grays Lake, Idaho
Science.gov (United States)
Austin, J.E.; Henry, A.R.; Ball, I.J.
2007-01-01
We examined population size and factors influencing nest survival of greater sandhill cranes (Grus canadensis tabida) at Grays Lake National Wildlife Refuge, Idaho, USA, during 1997-2000. Average local population of cranes from late April to early May, 1998-2000, was 735 cranes, 34% higher than that reported for May 1970-1971. We estimated 228 (SE = 30) nests in the basin core (excluding renests), 14% higher than a 1971 estimate. Apparent nest success in our study (x?? = 60%, n = 519 nests) was lower than reported for Grays Lake 30-50 years earlier. Daily survival rates (DSRs) of all nests averaged 0.9707 (41.2%). The best model explaining nest survival included year and water depth and their interaction. Nest survival was highest (DSR = 0.9827) in 1998 compared with other years (0.9698-0.9707). Nest survival changed little relative to water depth in 1998, when flooding was extensive and alternative prey (microtines) irrupted, but declined markedly with lower water levels in 2000, the driest year studied. Hypotheses relating nest survival to vegetation height, land use (idle, summer grazing, fall grazing), and date were not supported. In a before-after-control-impact design using 12 experimental fields, nest survival differed among years but not among management treatments (idle, fall graze, fall burn, and summer-graze-idle rotation), nor was there an interaction between year and treatments. However, DSRs in fall-burn fields declined from 0.9781 in 1997-1998 to 0.9503 in 1999-2000 (posttreatment). Changes in the predator community have likely contributed to declines in nest success since the 1950s and 1970s. Our results did not support earlier concerns about effects of habitat management practices on crane productivity. Nest survival could best be enhanced by managing spring water levels. Managers should continue censuses during late April to evaluate long-term relationships to habitat conditions and management.
19. Nesting ecology of waterbirds at Grays Lake, Idaho
Science.gov (United States)
Austin, J.E.; Pyle, W.H.
2004-01-01
Montane wetlands provide valuable habitat for nesting waterfowl and other waterbirds in the western United States, but relatively little information is available about the nesting ecology of their waterbird communities. We describe the general nesting ecology of breeding waterbirds at a large, shallow montane wetland in southeast Idaho during 1997-2000. Habitats included upland grasslands and intermittently to semipermanently flooded wetland habitats. We located a total of 1207 nests of 23 bird species: eared grebe (Podiceps nigricollis), Canada goose (Branta canadensis), mallard (Anas platyrhynchos), gadwall (A. strepera), American wigeon (A. americana), green-winged teal (A. crecca), blue-winged teal (A. discors), cinnamon teal (A. cyanoptera), northern shoveler (A. clypeata), northern pintail (A. acuta), redhead (Aythya americana), canvasback (A. valisineria), lesser scaup (A. affinis), ruddy duck (Oxyuris jamaicensis), northern harrier (Circus cyaneus), American coot (Fulica americana), Virginia rail (Rallus limicola), greater sandhill crane (Grus canadensis tabida), American avocet (Recurvirostra americana), long-billed curlew (Numenius americanus), Wilsons snipe (Gallinago delicta), Wilsons phalarope (Phalaropus tricolor), and short-eared owl (Asio flammeus). Most nests were initiated in May-early June and were terminated (hatched or destroyed) by the third week of June. Mean daily survival rate (DSR) for Canada goose nests was 0.954 0.005 (SE) (n = 127 nests), equivalent to Mayfield nest success of 21%. Mean DSR for dabbling duck nests over all four years was 0.938 0.006 (n = 141), equivalent to Mayfield nest success of 11%. For all other species where we found >10 nests each year (eared grebe, redhead, canvasback, coot, sandhill crane, American avocet, and Wilsons snipe), >50% of nests found hatched at least one young. Success rates for geese, cranes, and ducks were lower than reported for Grays Lake during 1949-1951 and lower than most other wetlands in
20. Generalized Derivations and Bilocal Jordan Derivations of Nest Algebras
Directory of Open Access Journals (Sweden)
Dangui Yan
2011-01-01
Full Text Available Let H be a complex Hilbert space and B(H the collection of all linear bounded operators, A is the closed subspace lattice including 0 an H, then A is a nest, accordingly alg A={T∈B(H:TN⊆N, ∀N∈A} is a nest algebra. It will be shown that of nest algebra, generalized derivations are generalized inner derivations, and bilocal Jordan derivations are inner derivations.
1. Duck nesting in intensively farmed areas of North Dakota
Science.gov (United States)
Higgins, K.F.
1977-01-01
A study to determine the major factors limiting duck nesting and production on intensively farmed areas in eastern North Dakota was conducted from 1969 through 1974. A total of 186 duck nests was found during searches on 6,018 ha of upland. Nest density per km2 for 5 major habitat types was 20.2 in untilled upland, 3.7 in standing grain stubble, 1.6 in mulched grain stubble, 1.2 in summer fallow, and 1.1 in growing grain. Pintails (Anas acuta) nested in cultivated cropland types in greater prevalence than other duck species. Nest densities were 12 times greater on untilled upland (20.2/km2) than on annually tilled cropland (1.7/km2), and hatched-clutch densities were 16 times greater on untilled upland (4.8/km2) than on annually tilled cropland (0.3/km2). Hatching success was greater on untilled upland (25%) than on tilled cropland (17%). Of 186 nests found, 77 percent did not hatch; 76 percent of the failures were attributed to predators and 19 percent to farming operations. Poor quality nesting cover, the result of intensive land use practices, and nesting failures caused by machinery and predators mainly mammals, were the principal factors limiting duck nesting and production on intensively farmed areas.
2. Nest success of grassland sparrows on reclaimed surface mines
Science.gov (United States)
Stauffer, G.E.; Diefenbach, D.R.; Marshall, M.R.; Brauning, D.W.
2011-01-01
Grasslands resulting from surface mine reclamation support grassland songbird populations in several midwestern and eastern states in the United States, especially where reclaimed mines are large (>1,000ha). However, most reclaimed surface mines in Pennsylvania are small (success is unknown. We evaluated nest success of grasshopper (Ammodramus savannarum), Henslow's (A. henslowii), and Savannah sparrows (Passerculus sandwichensis) on 4 reclaimed surface mines (50-180ha) in western Pennsylvania, USA from 2006 to 2007. Overall nest success based on mean covariate values was 0.435 (95% CI = 0.376-0.504) for grasshopper sparrows, 0.396 (95% CI = 0.295-0.533) for Henslow's sparrows, and 0.158 (95% CI = 0.063-0.392) for Savannah sparrows. These estimates of nest success are comparable to those on larger reclaimed mines and other habitats. Grasshopper and Henslow's sparrow nests that were well concealed were less likely to fail than highly visible nests (??visible = -0.028, CI = -0.051 to -0.005 for grasshopper sparrows; ??visible = -0.063, CI = -0.112 to -0.014 for Henslow's sparrows), and nests in areas with surrounding deep litter were more likely to fail than nests in areas with shallow litter (??litterD = -0.145, CI = -0.335 to 0.045 for grasshopper sparrows; ??litterD = -0.676, CI = -1.187 to -0.116 for Henslow's sparrows). Savannah sparrow nests in areas with high visual obstruction by vegetation were less likely to fail than nests in areas with sparse and short vegetation (??VisOb = 0.048, CI = 0.006-0.091). Daily probability of survival for grasshopper sparrow nests was greatest early and late in the breeding season, and Savannah sparrow nest survival followed a decreasing linear trend. Nest survival of Henslow's sparrows was greater on warm days (??temp = 0.197, CI = 0.014-0.379), whereas for Savannah sparrows nest survival decreased on warm days and on days with rain, but for Savannah sparrows confidence intervals of weather effects included zero (??temp = -0
3. Edible bird's nest: food or medicine?
Science.gov (United States)
Wong, Rebecca S Y
2013-09-01
Edible bird's nest (EBN) is derived from the saliva of certain types of swiftlets. It is consumed in many parts of the world for its nutritional and medicinal values. Although many claims have been made on the therapeutic and health-promoting effects of EBN, scientific documentations regarding these effects are very limited in published literature. It is not until recently that the biological effects of EBN are being investigated and evidence-based studies are being conducted. Several studies have found that EBN may enhance cell proliferation and differentiation and various beneficial effects have been reported in vitro as well as in vivo. While these studies point towards the potential use of EBN in the treatment or even prevention of several diseases, the mechanisms of action of EBN remain largely unknown and more explorations are needed. This review is one of the very few scientific reviews on EBN which focuses on recent evidence-based discoveries.
4. Development of the nested fiber filter
Science.gov (United States)
Litt, R. D.; Conkle, H. N.; Raghavan, J. K.
Battelle has tested the Nested Fiber Filter (NFF) as a particulate control device for high temperature, high-pressure (HTHP) applications. Battelle funded initial bench-scale tests which were the basis for patents and a concept applying the NFF. Subsequent parametric tests in a 6-inch diameter reactor established excellent particulate capture performance, greater than 99 percent, for conditions up to 1600 F and 6 atmospheres. Effective cleaning/regeneration of the NFF was achieved in the 6-inch scale with acoustic and mechanical vibration. A pulse combustor was tested in an integrated NFF arrangement because of compatibility with the HTBP conditions. This arrangement provided the basis for larger scale tests under the subject contract. A 6-sq ft test module was designed and installed with an existing fluidized bed combustor for additional development and testing.
5. Daily survival rate for nests and chicks of Least Terns (Sternula antillarum) at natural nest sites in South Carolina
Science.gov (United States)
Brooks, Gillian L.; Sanders, Felicia J.; Gerard, Patrick D.; Jodice, Patrick G.
2013-01-01
Although a species of conservation concern, little is known about the reproductive success of Least Terns (Sternula antillarum) throughout the southeastern USA where availability of natural beaches for nesting is limited. Daily survival rate (DSR) of nests and chicks was examined at four natural nesting sites in Cape Romain National Wildlife Refuge, South Carolina, 2009–2010. Measures of nest success (n = 257 nests) ranged from 0–93% among colony sites. The DSR of nests was primarily related to colony site, but year and estimates of predation risk also were related to DSR. Predation was the principal cause of identifiable nest loss, accounting for 47% of nest failures when the two years of data were pooled. The probability (± SE) of a chick surviving from hatching to fledging = 0.449 ± 0.01 (n = 92 chicks). DSR of chicks was negatively related to tide height and rainfall. Therefore, productivity of Least Terns is being lost during both the nesting and chick stage through a combination of biotic and abiotic factors that may prove difficult to fully mitigate or manage. Although natural nesting sites within Cape Romain National Wildlife Refuge intermittently produce successful nests, the consistency of productivity over the long term is still unknown. Given that the long term availability of anthropogenic nest sites (e.g., rooftops, dredge-spoil islands) for Least Terns is questionable, further research is required both locally and throughout the region to assess the extent to which natural sites act as population sources or sinks.
6. The effect of nesting material on the nest-building and maternal behavior of domestic sows and piglet production.
Science.gov (United States)
Chaloupková, H; Illmann, G; Neuhauserová, K; Simecková, M; Kratinová, P
2011-02-01
Nest building is an important part of maternal behavior in domestic pigs. The aim of the study was to assess the effect of nesting material sawdust vs. straw on sow behavior 24 h before and after birth of the first piglet (BFP) and piglet production. Sows, housed in farrowing crates, were randomly divided into 2 treatments: sawdust (n = 12) and straw (n = 13). Sawdust and straw were provided during the pre- and parturient period; after parturition, straw was given to both experimental groups. The prepartum nesting period (the time interval between the first and last nest-building records, including all other activity and resting before BFP), the nesting records (number of nesting records), nesting duration (duration of all nesting records), the start and termination of nesting, and the frequency of prepartum postural changes were collected 24 h before BFP. After BFP, number of nesting records and time to first sucking of the litter were collected. Frequency of postural changes and duration of udder access were collected 24 h after BFP during 3 time periods (during parturition, from the end of parturition to 12 h after BFP, and 12 to 24 h after BFP) and the frequency of nursing during 2 time periods (from the end of parturition to 12 h after BFP, and 12 to 24 h after BFP). Piglet BW gain and mortality were estimated 24 h after BFP. Data were analyzed using PROC MIXED and the probability of the piglet mortality using PROC GENMOD in SAS. Nesting material did not affect (P > 0.10) most of sow prepartum nesting behavior and had no effect (P > 0.10) on the prepartum frequency of postural changes. Sows from the sawdust treatment had a longer nesting period (P 0.10) of the nesting material on piglet BW gain and mortality was found. The results suggest that sawdust compared with straw as nesting material provided to sows before and through parturition does not negatively affect maternal behavior during the 24 h before and after parturition or piglet production. Therefore
7. Hatchling sex ratio, body weight and nest parameters for Chelonia mydas nesting on Sugözü beaches (Turkey
Directory of Open Access Journals (Sweden)
Kılıç, Ç.
2014-12-01
Full Text Available We investigated the relationship between nest parameters, hatchling body mass, and sex ratio of green turtle, Chelonia mydas, embryos and hatchlings at the temperate nesting rookery of Sugözü Beach (Adana–Turkey. Mean nest temperature and distance from the sea were correlated, while mean nest temperature and incubation period were inversely related. There was no apparent relationship between incubation period and hatchling mass. Hatchling and embryo sex ratios, determined by histological examination, showed a 70.5% and 93.5% female bias, respectively. There was no correlation between sex and body weight of hatchlings,
8. A hierarchical nest survival model integrating incomplete temporally varying covariates
Science.gov (United States)
Converse, Sarah J.; Royle, J. Andrew; Adler, Peter H.; Urbanek, Richard P.; Barzan, Jeb A.
2013-01-01
Nest success is a critical determinant of the dynamics of avian populations, and nest survival modeling has played a key role in advancing avian ecology and management. Beginning with the development of daily nest survival models, and proceeding through subsequent extensions, the capacity for modeling the effects of hypothesized factors on nest survival has expanded greatly. We extend nest survival models further by introducing an approach to deal with incompletely observed, temporally varying covariates using a hierarchical model. Hierarchical modeling offers a way to separate process and observational components of demographic models to obtain estimates of the parameters of primary interest, and to evaluate structural effects of ecological and management interest. We built a hierarchical model for daily nest survival to analyze nest data from reintroduced whooping cranes (Grus americana) in the Eastern Migratory Population. This reintroduction effort has been beset by poor reproduction, apparently due primarily to nest abandonment by breeding birds. We used the model to assess support for the hypothesis that nest abandonment is caused by harassment from biting insects. We obtained indices of blood-feeding insect populations based on the spatially interpolated counts of insects captured in carbon dioxide traps. However, insect trapping was not conducted daily, and so we had incomplete information on a temporally variable covariate of interest. We therefore supplemented our nest survival model with a parallel model for estimating the values of the missing insect covariates. We used Bayesian model selection to identify the best predictors of daily nest survival. Our results suggest that the black fly Simulium annulus may be negatively affecting nest survival of reintroduced whooping cranes, with decreasing nest survival as abundance of S. annulus increases. The modeling framework we have developed will be applied in the future to a larger data set to evaluate the
9. Local individual preferences for nest materials in a passerine bird.
Directory of Open Access Journals (Sweden)
Full Text Available BACKGROUND: Variation in the behavioural repertoire of animals is acquired by learning in a range of animal species. In nest-building birds, the assemblage of nest materials in an appropriate structure is often typical of a bird genus or species. Yet plasticity in the selection of nest materials may be beneficial because the nature and abundance of nest materials vary across habitats. Such plasticity can be learned, either individually or socially. In Corsican populations of blue tits Cyanistes caeruleus, females regularly add in their nests fragments of several species of aromatic plants during the whole breeding period. The selected plants represent a small fraction of the species present in the environment and have positive effects on nestlings. METHODOLOGY/PRINCIPAL FINDINGS: We investigated spatiotemporal variations of this behaviour to test whether the aromatic plant species composition in nests depends on 1 plant availability in territories, 2 female experience or 3 female identity. Our results indicate that territory plays a very marginal role in the aromatic plant species composition of nests. Female experience is not related to a change in nest plant composition. Actually, this composition clearly depends on female identity, i.e. results from individual preferences which, furthermore, are repeatable both within and across years. A puzzling fact is the strong difference in plant species composition of nests across distinct study plots. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that plant species composition of nests results from individual preferences that are homogeneous within study plots. We propose several hypotheses to interpret this pattern of spatial variation before discussing them in the light of preliminary results. As a conclusion, we cannot exclude the possibility of social transmission of individual preferences for aromatic plants. This is an exciting perspective for further work in birds, where nest construction
10. Nest survival of forest birds in the Mississippi Alluvial Valley
Science.gov (United States)
Twedt, D.J.; Wilson, R.R.; Henne-Kerr, J.L.; Hamilton, R.B.
2001-01-01
In the Mississippi Alluvial Valley, flood control has led to a drastic reduction in the area of forest habitat and altered the patchwork of forest cover types. Silvicultural management of the remaining fragmented forests has changed to reflect the altered hydrology of the forests, current economic conditions of the area, and demand for forest products. Because forest type and silvicultural management impact forest birds, differences in avian productivity within these forests directly impact bird conservation. To assist in conservation planning, we evaluated daily nest survival, nest predation rates, and brood parasitism rates of forest birds in relation to different forest cover types and silvicultural management strategies within this floodplain. Within bottomland hardwood forests, nest success of blue-gray gnatcatcher (Polioptila caerulea, 13%), eastern towhee (Pipilo erythrophthalmus, 28%), indigo bunting (Passerina cyanea, 18%), northern cardinal (Cardinalis cardinalis, 22%), and yellow-billed cuckoo (Coccyzus americanus, 18%) did not differ from that within intensively managed cottonwood plantations. However, average daily survival of 542 open-cup nests of 19 bird species in bottomland hardwoods (0.9516 + 0.0028, -27% nest success) was greater than that of 543 nests of 18 species in cotlonwood plantations (0.9298 + 0.0035, -15% nest success). Differences in daily nest survival rates likely resulted from a combination of differences in the predator community--particularly fire ants (Solenopsis invicta)--and a marked difference in species composition of birds breeding within these 2 forest types. At least 39% of nests in bottomland hardwood forests and 65% of nests in cottonwood plantations were depredated. Rates of parasitism by brown-headed cowbirds (Molothrus ater) were greater in managed cottonwoods (24%) than in bottomland hardwoods (9%). Nest success in planted cottonwood plantations for 18 species combined (-14%), and for yellow-breasted chat (Icteria
11. Factors affecting Culicoides species composition and abundance in avian nests.
Science.gov (United States)
Martínez-de la Puente, J; Merino, S; Tomás, G; Moreno, J; Morales, J; Lobato, E; Talavera, S; Sarto I Monteys, V
2009-08-01
Mechanisms affecting patterns of vector distribution among host individuals may influence the population and evolutionary dynamics of vectors, hosts and the parasites transmitted. We studied the role of different factors affecting the species composition and abundance of Culicoides found in nests of the blue tit (Cyanistes caeruleus). We identified 1531 females and 2 males of 7 different Culicoides species in nests, with C. simulator being the most abundant species, followed by C. kibunensis, C. festivipennis, C. segnis, C. truncorum, C. pictipennis and C. circumscriptus. We conducted a medicationxfumigation experiment randomly assigning bird's nests to different treatments, thereby generating groups of medicated and control pairs breeding in fumigated and control nests. Medicated pairs were injected with the anti-malarial drug Primaquine diluted in saline solution while control pairs were injected with saline solution. The fumigation treatment was carried out using insecticide solution or water for fumigated and control nests respectively. Brood size was the main factor associated with the abundance of biting midges probably because more nestlings may produce higher quantities of vector attractants. In addition, birds medicated against haemoparasites breeding in non-fumigated nests supported a higher abundance of C. festivipennis than the rest of the groups. Also, we found that the fumigation treatment reduced the abundance of engorged Culicoides in both medicated and control nests, thus indicating a reduction of feeding success produced by the insecticide. These results represent the first evidence for the role of different factors in affecting the Culicoides infracommunity in wild avian nests.
12. Common loon nest defense against an American mink
Science.gov (United States)
McCarthy, Kyle P.; Destefano, Stephen
2011-01-01
We describe a successful nest defense strategy of an adult Gavia immer (Common Loon) during an attempted predation event by a Nevison vison (American Mink) at Umbagog National Wildlife Refuge, NH. It is suspected that mink occasionally depredate loon nests, but defense strategies have not been described previously.
13. Preferences for nest boxes as environmental enrichment for laboratory mice
NARCIS (Netherlands)
Van de Weerd, HA; Van Loo, PLP; Van Zutphen, LFM; Koolhaas, JM; Baumans, [No Value
1998-01-01
In nature, mice live in burrows with nest chambers where they breed and may hide from predators. In the laboratory, a shelter or refuge is an easily applicable form of enrichment which may enhance the welfare of laboratory mice by giving them more control over their environment. Six nest boxes made
14. Animating Nested Taylor Polynomials to Approximate a Function
Science.gov (United States)
Mazzone, Eric F.; Piper, Bruce R.
2010-01-01
The way that Taylor polynomials approximate functions can be demonstrated by moving the center point while keeping the degree fixed. These animations are particularly nice when the Taylor polynomials do not intersect and form a nested family. We prove a result that shows when this nesting occurs. The animations can be shown in class or…
Energy Technology Data Exchange (ETDEWEB)
Lee, Jin Hee; Byun, Kyung Hwan; Jeon, Ji Min [College of Medicine, Pochon CHA University, Pochon (Korea, Republic of)
2005-07-15
Brunn nests are the most common proliferative lesions of the bladder uroepithelium, but exuberant proliferation can mimic bladder tumor on radiologic imaging and cystoscopy. We describe a case of pathologically proven Brunn nests in a 34-year-old man, misdiagnosed as bladder tumor on preoperative imaging studies.
16. Nest ectoparasites increase physiological stress in breeding birds: an experiment
Science.gov (United States)
Martínez-de La Puente, Josué; Merino, Santiago; Tomás, Gustavo; Moreno, Juan; Morales, Judith; Lobato, Elisa; Martínez, Javier
2011-02-01
Parasites are undoubtedly a biotic factor that produces stress. Heat shock proteins (HSPs) are important molecules buffering cellular damage under adverse conditions. During the breeding season, blue tit Cyanistes caeruleus (L.) adults are affected by blood parasites, nest-dwelling parasites and biting flies, potentially affecting their HSP-mediated responses. Here, we treated females with primaquine to reduce blood parasites and fumigated nests with permethrin to reduce nest-dwelling parasites to test whether these treatments affect HSP60 level during the breeding season. Medicated females, but not controls, had a significant reduction of the intensity of infection by Haemoproteus spp. blood parasites. However, final intensity of infection did not differ significantly between groups, and we did not find an effect of medication on change in HSP60 level. Fumigation reduced the abundance of nest-dwelling parasites (mites, fleas and blowfly larvae) and engorged biting midges in nests. Females breeding in non-fumigated nests increased HSP60 levels during the season more than those breeding in fumigated nests. Furthermore, the change in HSP60 level was positively correlated with the abundance of biting midges. These results show how infections by nest ectoparasites during the breeding period can increase the level of HSPs and suggest that biting midges impose physiological costs on breeding female blue tits. Although plausible, the alternative that biting midges prefer to feed on more stressed birds is poorly supported by previous studies.
17. A new method for wireless video monitoring of bird nests
Science.gov (United States)
David I. King; Richard M. DeGraaf; Paul J. Champlin; Tracey B. Champlin
2001-01-01
Video monitoring of active bird nests is gaining popularity among researchers because it eliminates many of the biases associated with reliance on incidental observations of predation events or use of artificial nests, but the expense of video systems may be prohibitive. Also, the range and efficiency of current video monitoring systems may be limited by the need to...
18. Influence of nest box environment on kit survival
DEFF Research Database (Denmark)
Lund, V.H.; Malmkvist, Jens
2012-01-01
. In conclusion, access to different nesting materials reduced the risk of dying in farm mink in relation with factors as e.g. nest quality and maternal behaviour. A decrease in kit mortality from 20% to 5% would give the Danish mink production a profound number of Danish kroner extra per year....
19. Long-eared owls nesting in Badlands National Park
Science.gov (United States)
Deborah D. Paulson; Carolyn Hull Sieg
1985-01-01
Long-eared Owls nest at high densities locally over the Great Plains where suitable habitat is limited (Bent 1938), yet , according to Whitney et al. (1978), this species is rare to uncommon in South Dakota. Especially west of the Missouri River, few nesting records have been reported. This paper reports the occurrence of Long-eared Owls in the Badlands National Park...
20. Nesting habitat and productivity of Swainson's Hawks in southeastern Arizona
Science.gov (United States)
Nishida, Catherine; Boal, Clint W.; DeStefano, Stephen; Hobbs, Royden J.
2013-01-01
We studied Swainson's Hawks (Buteo swainsoni) in southeastern Arizona to assess the status of the local breeding population. Nest success (≥1 young fledged) was 44.4% in 1999 with an average of 1.43 ± 0.09 (SE) young produced per successful pair. Productivity was similar in 2000, with 58.2% nesting success and 1.83 ± 0.09 fledglings per successful pair. Mesquite (Prosopis velutina) and cottonwood (Populus fremontii) accounted for >50% of 167 nest trees. Nest trees were taller than surrounding trees and random trees, and overall there was more vegetative cover at nest sites than random sites. This apparent requirement for cover around nest sites could be important for management of the species in Arizona. However, any need for cover at nest sites must be balanced with the need for open areas for foraging. Density of nesting Swainson's Hawks was higher in agriculture than in grasslands and desert scrub. Breeding pairs had similar success in agricultural and nonagricultural areas, but the effect of rapid and widespread land-use change on breeding distribution and productivity continues to be a concern throughout the range of the species.
1. LOGGERHEAD SEA TURTLE LATE NESTING ECOLOGY IN VIRGINIA BEACH, VIRGINIA
Science.gov (United States)
T'he.loggerhead sea turtle (Caretta came is the only recurrent nesting species of sea turtle in southeastern Virginia (Lutcavage & Musick, 1985; Dodd, 1988). Inasmuch as the loggerhead is a federally threatened species, the opportunity to gather data on its nesting ecology is imp...
2. Nesting behavior of Trypoxylon (Trypargilum agamemnom Richards (Hymenoptera: Crabronidae
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MLT Buschini
Full Text Available Nesting behaviour is extremely diversified among solitary nesting sphecids. Thus, the aim of this study was to describe the nesting behaviour of Trypoxylon agamemnon and discuss the advantages of guarding behaviour of males. It was conducted in the Parque Municipal das Araucárias, Guarapuava (PR, Brazil from October/2003 to July/2007. To describe the behaviour of T. agamemnon and construct its ethogram, daily observations were made, totalling 410:19 hours observation. Although the males of T. agamemnon stand guard close to the entrance of the nests, we concluded that this behaviour is not ensuring the protection of nests against parasitoids and that, probably, this behaviour ensures them the paternity, but further studies with microsatellite markers will be necessary to confirm this hypothesis.
3. Nesting behavior of Trypoxylon (Trypargilum) agamemnom Richards (Hymenoptera: Crabronidae).
Science.gov (United States)
Buschini, M L T; Donatti, A J
2012-05-01
Nesting behaviour is extremely diversified among solitary nesting sphecids. Thus, the aim of this study was to describe the nesting behaviour of Trypoxylon agamemnon and discuss the advantages of guarding behaviour of males. It was conducted in the Parque Municipal das Araucárias, Guarapuava (PR), Brazil from October/2003 to July/2007. To describe the behaviour of T. agamemnon and construct its ethogram, daily observations were made, totalling 410:19 hours observation. Although the males of T. agamemnon stand guard close to the entrance of the nests, we concluded that this behaviour is not ensuring the protection of nests against parasitoids and that, probably, this behaviour ensures them the paternity, but further studies with microsatellite markers will be necessary to confirm this hypothesis.
4. Nest predation research: Recent findings and future perspectives
Science.gov (United States)
Chalfoun, Anna D.; Ibanez-Alamo, J. D.; Magrath, R. D.; Schmidt, Kenneth A.; Thomson, R. L.; Oteyza, Juan C.; Haff, T. M.; Martin, T.E.
2016-01-01
Nest predation is a key source of selection for birds that has attracted increasing attention from ornithologists. The inclusion of new concepts applicable to nest predation that stem from social information, eavesdropping or physiology has expanded our knowledge considerably. Recent methodological advancements now allow focus on all three players within nest predation interactions: adults, offspring and predators. Indeed, the study of nest predation now forms a vital part of avian research in several fields, including animal behaviour, population ecology, evolution and conservation biology. However, within nest predation research there are important aspects that require further development, such as the comparison between ecological and evolutionary antipredator responses, and the role of anthropogenic change. We hope this review of recent findings and the presentation of new research avenues will encourage researchers to study this important and interesting selective pressure, and ultimately will help us to better understand the biology of birds.
5. Vares ja kana : [valmid] / Ivan Krõlov ; tlk. Eduard Kansa, Mart Raud, Timotheos Kuusik, Johannes Semper, G. Õis, Arnold Tulik, Oskar Urgart, Jaan Kärner, Jakob Tamm, Erni Hiir
Index Scriptorium Estoniae
Krõlov, Ivan, 1768(1769)-1844
2006-01-01
Sisu: Vares ja Kana ; Moosekandid ; Vares ja Rebane ; Konn ja Härg ; Pirtsakas Näitsik ; Oraakel ; Rukkilill ; Tuli ja Metsatukk ; Hunt ja Talleke ; Pärdik ja Prillid ; Ahvid ; Tihane ; Eesel ; Kotkas ja Kanad ; Võimumees ja Mõttetark ; Koerte sõprus ; Kasujaotus ; Vaat ; Kvartett ; Teekäijad ja Koerad ; Hunt penilas ; Oja ; Rebane ja Mäger ; Rohutirts ja Sipelgas ; Luiskaja ; Kukk ja Pärlitera ; Jänes jahil ; Hunt ja Kägu ; Haug ja Kass ; Peremees ja Sulane ; Voor ; Elevant maavalitsejaks ; Eesel ja Ööbik ; Külamehe kimbatus ; Elevant ja Mops ; Hunt ja tema Kutsikas ; Kass ja Kokk ; Lõvi ja Sääsk ; Aednik ja Filosoof ; Haned ; Siga ; Vanamees ja kolm noorukit ; Kotkas ja Ämblik ; Lehed ja Juured ; Hunt ja Rebane ; Lohe ; Rästas ; Mehhaanik ; Trishka satter ; Tiik ja Jõgi ; Luik, Haug ja Vähk ; Erak ja Karu ; Mesilane ja Kärbsed ; Lõvi jahisaak ; Talupojad ja Jõgi ; Lilled ; Uudishimulik ; Kaastundlik Rebane ; Kogukonna koosolek ; Demjani kalasupp ; Tihane ja Tuvi ; Hiir ja Rott ; Peegel ja Ahv ; Sääsk ja Karjane ; Talupoeg ja Surm ; Hunt ja Karjased ; Lõvi ja Rebane ; Kamm ; Hunt ja Kurg ; Pilv ; Poiss ja Siug ; Maamees ja Siug ; Kägu ja Tuvike ; Kaks Vaati ; Töökas Karu ; Rebane ja Viinamarjad ; Karu võrgus ; Kirjamees ja Röövel ; Mölder ; Siga Tamme all ; Kärbes ja Mesilane ; Ämblik ja Mesilane ; Rebane ja Eesel ; Siug ja Talleke ; Ööbikud ; Peremes ja Lammas ; Kaks Külameest ; Kaks Koera ; Kass ja Ööbik ; Kalade tants ; Haug ; Habemenoad ; Hiired ; Hunt ja Kass ; Karjane ; Orav ; Damaskuse mõõk ; Koer ja Hobune ; Rebane ; Hundid ja Lambad ; Kägu ja Kukk
6. Vares ja kana : [valmid] / Ivan Krõlov ; tlk. Eduard Kansa, Mart Raud, Timotheos Kuusik, Johannes Semper, G. Õis, Arnold Tulik, Oskar Urgart, Jaan Kärner, Jakob Tamm, Erni Hiir
Index Scriptorium Estoniae
Krõlov, Ivan, 1768(1769)-1844
2006-01-01
Sisu: Vares ja Kana ; Moosekandid ; Vares ja Rebane ; Konn ja Härg ; Pirtsakas Näitsik ; Oraakel ; Rukkilill ; Tuli ja Metsatukk ; Hunt ja Talleke ; Pärdik ja Prillid ; Ahvid ; Tihane ; Eesel ; Kotkas ja Kanad ; Võimumees ja Mõttetark ; Koerte sõprus ; Kasujaotus ; Vaat ; Kvartett ; Teekäijad ja Koerad ; Hunt penilas ; Oja ; Rebane ja Mäger ; Rohutirts ja Sipelgas ; Luiskaja ; Kukk ja Pärlitera ; Jänes jahil ; Hunt ja Kägu ; Haug ja Kass ; Peremees ja Sulane ; Voor ; Elevant maavalitsejaks ; Eesel ja Ööbik ; Külamehe kimbatus ; Elevant ja Mops ; Hunt ja tema Kutsikas ; Kass ja Kokk ; Lõvi ja Sääsk ; Aednik ja Filosoof ; Haned ; Siga ; Vanamees ja kolm noorukit ; Kotkas ja Ämblik ; Lehed ja Juured ; Hunt ja Rebane ; Lohe ; Rästas ; Mehhaanik ; Trishka satter ; Tiik ja Jõgi ; Luik, Haug ja Vähk ; Erak ja Karu ; Mesilane ja Kärbsed ; Lõvi jahisaak ; Talupojad ja Jõgi ; Lilled ; Uudishimulik ; Kaastundlik Rebane ; Kogukonna koosolek ; Demjani kalasupp ; Tihane ja Tuvi ; Hiir ja Rott ; Peegel ja Ahv ; Sääsk ja Karjane ; Talupoeg ja Surm ; Hunt ja Karjased ; Lõvi ja Rebane ; Kamm ; Hunt ja Kurg ; Pilv ; Poiss ja Siug ; Maamees ja Siug ; Kägu ja Tuvike ; Kaks Vaati ; Töökas Karu ; Rebane ja Viinamarjad ; Karu võrgus ; Kirjamees ja Röövel ; Mölder ; Siga Tamme all ; Kärbes ja Mesilane ; Ämblik ja Mesilane ; Rebane ja Eesel ; Siug ja Talleke ; Ööbikud ; Peremes ja Lammas ; Kaks Külameest ; Kaks Koera ; Kass ja Ööbik ; Kalade tants ; Haug ; Habemenoad ; Hiired ; Hunt ja Kass ; Karjane ; Orav ; Damaskuse mõõk ; Koer ja Hobune ; Rebane ; Hundid ja Lambad ; Kägu ja Kukk
7. Directed random polymers via nested contour integrals
Science.gov (United States)
Borodin, Alexei; Bufetov, Alexey; Corwin, Ivan
2016-05-01
We study the partition function of two versions of the continuum directed polymer in 1 + 1 dimension. In the full-space version, the polymer starts at the origin and is free to move transversally in R, and in the half-space version, the polymer starts at the origin but is reflected at the origin and stays in R-. The partition functions solve the stochastic heat equation in full-space or half-space with mixed boundary condition at the origin; or equivalently the free energy satisfies the Kardar-Parisi-Zhang equation. We derive exact formulas for the Laplace transforms of the partition functions. In the full-space this is expressed as a Fredholm determinant while in the half-space this is expressed as a Fredholm Pfaffian. Taking long-time asymptotics we show that the limiting free energy fluctuations scale with exponent 1 / 3 and are given by the GUE and GSE Tracy-Widom distributions. These formulas come from summing divergent moment generating functions, hence are not mathematically justified. The primary purpose of this work is to present a mathematical perspective on the polymer replica method which is used to derive these results. In contrast to other replica method work, we do not appeal directly to the Bethe ansatz for the Lieb-Liniger model but rather utilize nested contour integral formulas for moments as well as their residue expansions.
8. Fermi Surface Nesting in UGe_2
Science.gov (United States)
Wang, F.; Allen, J. W.; Denlinger, J. D.; Rossnagel, Kai; Huxley, A. D.; Flouquet, J.
2004-03-01
UGe2 is of high current interest in connection with the possible role of ferromagnetic fluctuations in its pressure induced superconductivity, for which the Fermi surface (FS) is thought to be important. The band structure and FS contours of a single crystal have been measured using resonant angle-resolved photoemission near the U 5d to 5f edge. The measured dominant large sheet Fermi surface contour shows good agreement with magneto-oscillatory orbit frequencies, but with a much simpler diamond-like shape as compared to LDA and LDA+U band calculations. The measured FS topology is suggestive of a possible diagonal nesting condition different than previously proposed for SCDW models of the ferromagnetic transition(s) in UGe2 and allows assessment of FS topology-driven models of the ferromagnetic superconductor phase diagram.(e.g. K.G. Sandeman et al.), Phys. Rev. Lett. 90, 167005 (2003). Supported by the U.S. NSF at U. Mich. (DMR-03-02825) and by the DOE at the Advanced Light Source (DE-AC03-76SF00098).
9. Nest Success and Cause-Specific Nest Failure of Grassland Passerines Breeding in Prairie Grazed by Livestock
Science.gov (United States)
This manuscript describes two years of field research on ground-nesting songbird species at Zumwalt Prairie Reserve, northeastern Oregon, USA. Cattle-grazing has long been suspected in declines of ground-nesting songbirds in grazed grassland, primarily due to increased trampling...
10. Effects of timber size-class on predation of artificial nests in extensive forest
Science.gov (United States)
Richard M. DeGraaf; Per. Angelstam
1993-01-01
Depredation on artificial ground and cup nests in even-aged seedling/sapling, pole, and mature stands of continuous northern hardwood forest was studied in the White Mountain National Forest in New Hampshire, USA from May to June 1988. Track-board nests were used to identify predators of ground nests; plain ground nests and cup nests were used to investigate the...
11. Contrasting Effects of Cattle Grazing Intensity on Upland-Nesting Duck Production at Nest and Field Scales in the Aspen Parkland, Canada
Directory of Open Access Journals (Sweden)
Jeffrey M. Warren
2008-12-01
Full Text Available The Aspen Parkland of Canada is one of the most important breeding areas for temperate nesting ducks in North America. The region is dominated by agricultural land use, with approximately 9.3 million ha in pasture land for cattle grazing. However, the effects of using land for cattle grazing on upland-nesting duck production are poorly understood. The current study was undertaken during 2001 and 2002 to investigate how nest density and nesting success of upland-nesting ducks varied with respect to the intensity of cattle grazing in the Aspen Parkland. We predicted that the removal and trampling of vegetation through cattle grazing would reduce duck nest density. Both positive and negative responses of duck nesting success to grazing have been reported in previous studies, leading us to test competing hypotheses that nesting success would (1 decline linearly with grazing intensity or (2 peak at moderate levels of grazing. Nearly 3300 ha of upland cover were searched during the study. Despite extensive and severe drought, nest searches located 302 duck nests. As predicted, nest density was higher in fields with lower grazing intensity and higher pasture health scores. A lightly grazed field with a pasture score of 85 out of a possible 100 was predicted to have 16.1 nests/100 ha (95% CI = 11.7–22.1, more than five times the predicted nest density of a heavily grazed field with a pasture score of 58 (3.3 nests/100 ha, 95% CI = 2.2–4.5. Nesting success was positively related to nest-site vegetation density across most levels of grazing intensity studied, supporting our hypothesis that reductions in vegetation caused by grazing would negatively affect nesting success. However, nesting success increased with grazing intensity at the field scale. For example, nesting success for a well-concealed nest in a lightly grazed field was 11.6% (95% CI = 3.6–25.0%, whereas nesting success for a nest with the same level of nest-site vegetation in a heavily
12. Nesting ecology of roseate spoonbills at Nueces Bay, Texas
Science.gov (United States)
White, D.H.; Mitchell, C.A.; Cromartie, E.
1982-01-01
We conducted a study in 1978-1980 of the nesting ecology of Roseate Spoonbills (Ajaia ajaja) in a relatively polluted environment at Nueces Bay, Texas. For 154 marked nests, the average clutch size was 3.0 eggs; 73% of the eggs hatched, and 87% of the nests were successful (hatched at least 1 young). The average nest success rate (total fledglings:total eggs) was 50% or 1.5 fledglings per total nests. Incubation began the day after the first egg was laid, and the incubation period for each egg was 22 days. Eggs hatched in the order that they were laid; the first and second eggs hatched on consecutive days, and the second, third, and fourth eggs hatched every other day. Nest composition and size were highly consistent, but nest placement varied considerably and was dependent on the vegetative configuration of the dredge-material islands. Growth rate of nestlings conformed to a 'standard' growth curve, where body weight of nestlings at fledging equaled that of adults. There was no difference in weight gain among siblings based on actual age. Nestlings fledged at about 6 weeks of age, when feather development was complete. At fledging, the bills of juveniles had almost reached adult width, but bill length was only 67% that of adults. In general, environmental pollutants were low (Nueces Bay, Texas, though the area is surrounded by industries and agricultural lands. Apparently, spoonbills are less sensitive to these contaminants than are other aquatic species
13. Red-shouldered hawk nesting habitat preference in south Texas
Science.gov (United States)
Strobel, Bradley N.; Boal, Clint W.
2010-01-01
We examined nesting habitat preference by red-shouldered hawks Buteo lineatus using conditional logistic regression on characteristics measured at 27 occupied nest sites and 68 unused sites in 2005–2009 in south Texas. We measured vegetation characteristics of individual trees (nest trees and unused trees) and corresponding 0.04-ha plots. We evaluated the importance of tree and plot characteristics to nesting habitat selection by comparing a priori tree-specific and plot-specific models using Akaike's information criterion. Models with only plot variables carried 14% more weight than models with only center tree variables. The model-averaged odds ratios indicated red-shouldered hawks selected to nest in taller trees and in areas with higher average diameter at breast height than randomly available within the forest stand. Relative to randomly selected areas, each 1-m increase in nest tree height and 1-cm increase in the plot average diameter at breast height increased the probability of selection by 85% and 10%, respectively. Our results indicate that red-shouldered hawks select nesting habitat based on vegetation characteristics of individual trees as well as the 0.04-ha area surrounding the tree. Our results indicate forest management practices resulting in tall forest stands with large average diameter at breast height would benefit red-shouldered hawks in south Texas.
14. Extreme sequential polyandry insures against nest failure in a frog.
Science.gov (United States)
Byrne, Phillip G; Keogh, J Scott
2009-01-07
Sequential polyandry may evolve as an insurance mechanism to reduce the risk of choosing a mate that is infertile, closely related, genetically inferior or incompatible, but polyandry also might insure against nest failure in unpredictable environments. Most animals are oviparous, and in species where males provide nest sites whose quality varies substantially and unpredictably, polyandrous females might insure offspring success by distributing their eggs across multiple nests. Here, we test this hypothesis in a wild population of an Australian terrestrial toadlet, a polyandrous species, where males construct nests and remain with broods. We found that females partitioned their eggs across the nests of two to eight males and that more polyandrous females gained a significant increase in mean offspring survivorship. Our results provide evidence for the most extreme case of sequential polyandry yet discovered in a vertebrate and also suggest that insurance against nest failure might favour the evolution of polyandry. We propose that insurance against nest failure might be widespread among oviparous taxa and provide an important explanation for the prevalence of sequential polyandry in nature.
15. An object-oriented approach to nested data parallelism
Science.gov (United States)
Sheffler, Thomas J.; Chatterjee, Siddhartha
1994-01-01
This paper describes an implementation technique for integrating nested data parallelism into an object-oriented language. Data-parallel programming employs sets of data called 'collections' and expresses parallelism as operations performed over the elements of a collection. When the elements of a collection are also collections, then there is the possibility for 'nested data parallelism.' Few current programming languages support nested data parallelism however. In an object-oriented framework, a collection is a single object. Its type defines the parallel operations that may be applied to it. Our goal is to design and build an object-oriented data-parallel programming environment supporting nested data parallelism. Our initial approach is built upon three fundamental additions to C++. We add new parallel base types by implementing them as classes, and add a new parallel collection type called a 'vector' that is implemented as a template. Only one new language feature is introduced: the 'foreach' construct, which is the basis for exploiting elementwise parallelism over collections. The strength of the method lies in the compilation strategy, which translates nested data-parallel C++ into ordinary C++. Extracting the potential parallelism in nested 'foreach' constructs is called 'flattening' nested parallelism. We show how to flatten 'foreach' constructs using a simple program transformation. Our prototype system produces vector code which has been successfully run on workstations, a CM-2, and a CM-5.
16. Interspecific nest parasitism by chukar on greater sage-grouse
Science.gov (United States)
Fearon, Michelle L.; Coates, Peter S.
2014-01-01
Nest parasitism occurs when a female bird lays eggs in the nest of another and the host incubates the eggs and may provide some form of parental care for the offspring (Lyon and Eadie 1991). Precocial birds (e.g., Galliformes and Anseriformes) are typically facultative nest parasites of both their own and other species (Lyon and Eadie 1991). This behavior increases a female’s reproductive success when she parasitizes other nests while simultaneously raising her own offspring. Both interspecific and conspecific nest parasitism have been well documented in several families of the order Galliformes, particularly the Phasianidae (Lyon and Eadie 1991, Geffen and Yom-Tov 2001, Krakauer and Kimball 2009). The Chukar (Alectoris chukar) has been widely introduced as a game bird to western North America from Eurasia and is now well established within the Great Basin from northeastern California east to Utah and north to Idaho and Oregon (Christensen 1996). Over much of this range the Chukar occurs with other phasianids, including the native Greater Sage-Grouse (Centrocercus urophasianus), within sagebrush (Artemisia spp.) steppe (Christensen 1996, Schroeder et al. 1999, Connelly et al. 2000). Chukar typically exploit a broader range of habitats than do sage-grouse, but both species use the same species of sagebrush and other shrubs for nesting cover (Christensen 1996, Schroeder et al. 1999). Chukar are known to parasitize nests of other individuals of their own species (Geffen and Yom-Tov 2001), but we are unaware of reported evidence that Chukar may parasitize nests of sage-grouse. Here we describe a case of a Chukar parasitizing a sage-grouse nest in the sagebrush steppe of western Nevada.
17. Archiving California’s historical duck nesting data
Science.gov (United States)
Ackerman, Joshua T.; Herzog, Mark P.; Brady, Caroline; Eadie, John M.; Yarris, Greg S.
2015-07-14
The U.S. Geological Survey (USGS), in partnership with the California Waterfowl Association (CWA) and other organizations, have compiled large datasets on the nesting ecology and management of dabbling ducks and associated upland nesting birds (Northern Harriers [Circus cyaneus], Short-eared Owls [Asio flammeus], Ring-necked Pheasants [Phasianus colchicus], and American Bitterns [Botaurus lentiginosus]) throughout California on Federal Refuges, State Wildlife Areas, and private lands, some participating in State and Federal habitat programs. These datasets encompass several long-term monitoring programs at multiple sites throughout California, and include data from more than 26,000 nests and span nearly 30 years.
18. Nested Hilbert schemes on surfaces: Virtual fundamental class
DEFF Research Database (Denmark)
Gholampour, Amin; Sheshmani, Artan; Yau, Shing-Tung
2017-01-01
We construct natural virtual fundamental classes for nested Hilbert schemes on a nonsingular projective surface S. This allows us to define new invariants of S that recover some of the known important cases such as Poincare invariants of Durr-Kabanov-Okonek and the stable pair invariants of Kool......-Thomas. In the case of the nested Hilbert scheme of points, we can express these invariants in terms of integrals over the products of Hilbert scheme of points on S, and relate them to the vertex operator formulas found by Carlsson-Okounkov. The virtual fundamental classes of the nested Hilbert schemes play a crucial...
19. Spatiotemporal patterns of duck nest density and predation risk: a multi-scale analysis of 18 years and more than 10,000 nests
Science.gov (United States)
Ringelman, Kevin M.; Eadie, John M.; Ackerman, Joshua T.; Sih, Andrew; Loughman, Daniel L.; Yarris, Gregory S.; Oldenburger, Shaun L.; McLandress, M. Robert
2017-01-01
Many avian species are behaviorally-plastic in selecting nest sites, and may shift to new locations or habitats following an unsuccessful breeding attempt. If there is predictable spatial variation in predation risk, the process of many individuals using prior experience to adaptively change nest sites may scale up to create shifting patterns of nest density at a population level. We used 18 years of waterfowl nesting data to assess whether there were areas of consistently high or low predation risk, and whether low-risk areas increased, and high-risk areas decreased in nest density the following year. We created kernel density maps of successful and unsuccessful nests in consecutive years and found no correlation in predation risk and no evidence for adaptive shifts, although nest density was correlated between years. We also examined between-year correlations in nest density and nest success at three smaller spatial scales: individual nesting fields (10–28 ha), 16-ha grid cells and 4-ha grid cells. Here, results were similar across all scales: we found no evidence for year-to-year correlation in nest success but found strong evidence that nest density was correlated between years, and areas of high nest success increased in nest density the following year. Prior research in this system has demonstrated that areas of high nest density have higher nest success, and taken together, our results suggest that ducks may adaptively select nest sites based on the local density of conspecifics, rather than the physical location of last year's nest. In unpredictable environments, current cues, such as the presence of active conspecific nests, may be especially useful in selecting nest sites. The cues birds use to select breeding locations and successfully avoid predators deserve continued attention, especially in systems of conservation concern.
20. Incorporation of cigarette butts into nests reduces nest ectoparasite load in urban birds: new ingredients for an old recipe?
Science.gov (United States)
Suárez-Rodríguez, Monserrat; López-Rull, Isabel; Garcia, Constantino Macías
2013-02-23
Birds are known to respond to nest-dwelling parasites by altering behaviours. Some bird species, for example, bring fresh plants to the nest, which contain volatile compounds that repel parasites. There is evidence that some birds living in cities incorporate cigarette butts into their nests, but the effect (if any) of this behaviour remains unclear. Butts from smoked cigarettes retain substantial amounts of nicotine and other compounds that may also act as arthropod repellents. We provide the first evidence that smoked cigarette butts may function as a parasite repellent in urban bird nests. The amount of cellulose acetate from butts in nests of two widely distributed urban birds was negatively associated with the number of nest-dwelling parasites. Moreover, when parasites were attracted to heat traps containing smoked or non-smoked cigarette butts, fewer parasites reached the former, presumably due to the presence of nicotine. Because urbanization changes the abundance and type of resources upon which birds depend, including nesting materials and plants involved in self-medication, our results are consistent with the view that urbanization imposes new challenges on birds that are dealt with using adaptations evolved elsewhere.
1. Interaction between the solitary bee Chelostoma florisomne and its nest parasite Sapyga clavicornis-empty cells reduce the impact of parasites
DEFF Research Database (Denmark)
Munster-Swendsen, Mikael; Calabuig, Isabel
2000-01-01
Chelostoma, empty cells, interaction, mortality, nest architecture, nest parasite, protection, Sapyga, solitary bee......Chelostoma, empty cells, interaction, mortality, nest architecture, nest parasite, protection, Sapyga, solitary bee...
2. 1990 Flathead Valley duck nesting study progress report
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This informal progress report describes predator removal practices in the Lake County area, and observed waterfowl nest success. Species-specific data are...
3. Inkjet printing of silk nest arrays for cell hosting.
Science.gov (United States)
Suntivich, Rattanon; Drachuk, Irina; Calabrese, Rossella; Kaplan, David L; Tsukruk, Vladimir V
2014-04-14
An inkjet printing approach is presented for the facile fabrication of microscopic arrays of biocompatible silk "nests" capable of hosting live cells for prospective biosensors. The patterning of silk fibroin nests were constructed by the layer-by-layer (LbL) assembly of silk polyelectrolytes chemically modified with poly-(l-lysine) and poly-(l-glutamic acid) side chains. The inkjet-printed silk circular regions with a characteristic "nest" shape had diameters of 70-100 μm and a thickness several hundred nanometers were stabilized by ionic pairing and by the formation of the silk II crystalline secondary structure. These "locked-in" silk nests remained anchored to the substrate during incubation in cell growth media to provide a biotemplated platform for printing-in, immobilization, encapsulation and growth of cells. The process of inkjet-assisted printing is versatile and can be applied on any type of substrate, including rigid and flexible, with scalability and facile formation.
4. 1993 waterfowl nesting success on Fish Springs National Wildlife Refuge
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Report on an investigation of nesting success and factors affecting it on Fish Springs National Wildlife Refuge. Baseline information on trust species within the...
5. Wading bird nesting survey Fish Springs National Wildlife Refuge
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This report discusses results of a wading bird survey conducted at Fish Springs National Wildlife Refuge. The objectives of the survey include; 1) quantify nest site...
6. 2005 nest success data : Klettke WPA predator exclosure
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Report summarizing nest success at Klettke Waterfowl Production Area predator exclosure on Kulm wetland Management District in 2005. In 2005, the Klettke predator...
7. Contaminant exposure of white pelicans nesting at Anaho Island NWR
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Reproductive success of American white pelicans (Pelecanus erythrorhynchus) was monitored at a nesting colony on Anaho Island, Pyramid Lake, Nevada in 1996. Eggs...
8. Bald Eagle Summary Report for New York Nesting Territories 1991
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Observations at New York bald eagle nest sites one, three and four in Livingston, Genesee, and Seneca Counties respectively, continued during the 1991 breeding...
9. Application of nested sampling in statistical physics: the Potts model
CERN Document Server
Pfeifenberger, Manuel J
2016-01-01
We present a systematic benchmark study of the nested sampling algorithm on the basis of the Potts model. This model exhibits a first order phase transition for $q>4$ at the critical temperature. The numerical evaluation of the partition function and thermodynamic observables, which involves high dimensional sums of sharply structured multi-modal density functions, represents a major challenge to most standard numerical techniques, such as Markov Chain Monte Carlo. Nested sampling, on the other hand, is particularly suited for such problems. In this paper we will employ both, nested sampling and thermodynamic integration to evaluate the partition function of the Potts model. In both cases individual moves are based on Swendsen-Wang updates. A autocorrelation time analysis of both algorithms shows that the severe slowing down of thermodynamic integration around the critical temperature does not occur in nested sampling. In addition we show, how thermodynamic variables can be computed with high accuracy from th...
10. The Food and nesting Habits of the Bald Eagle
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This report summarizes the observations of the author who watched a bald eagle and studied its food habits at two nests. At the time of the report, the bald eagle...
11. Bald Eagle Summary Report for New York Nesting Territories 1990
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Observations at New York bald eagle nest sites one, three and four in Livingston, Genesee, and Seneca Counties respectively, continued during the 1990 breeding...
12. Nest losses in grazed vs. ungrazed waterfowl habitat
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — A fair number of managers, with student help, have just completed a series of dummy nest studies which sampled grazed and ungrazed habitat. I have examined 40...
13. History of Waterfowl Nesting on the Patuxent Research Center
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This report is a summary of waterfowl counts, waterfowl research, waterfowl nesting, and waterfowl records at Patuxent Research Refuge from 1963 through 2008, as...
14. Medium Range Forecast (MRF) and Nested Grid Model (NGM)
Data.gov (United States)
National Oceanic and Atmospheric Administration, Department of Commerce — The Nested Grid Model (NGM) and Medium Range Forecast (MRF) Archive is historical digital data set DSI-6140, archived at the NOAA National Centers for Environmental...
15. 1970 American Eagle Nest Survey of the Chesapeake Bay Region.
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Data refers to the 1970 nesting season for the Bald Eagle in the Chesapeake area to include Virginia and Maryland. The 1970 results are most disappointing since...
16. Bald Eagle Summary Report for New York Nesting Territories 1989
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Observations at New York bald eagle nest sites one, three and four in Livingston, Genesee, and Seneca Counties respectively, continued during the 1989 breeding...
17. Inventory and monitoring of red-cockaded woodpecker Nesting
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Report provides nesting monitoring and group size summary data associated with the red-cockaded woodpecker population at Noxubee NWR in 2012.
18. EXTREME POINTS IN DIAGONAL-DISJOINT IDEALS OF NEST ALGEBRAS
Institute of Scientific and Technical Information of China (English)
董浙; 鲁世杰
2002-01-01
In this paper, the extreme points of the unit ball of diagonal-disjoint ideals in nest algebras are characterized completely; Furthermore, it is shown that every extreme point of the unit ball of 2 has essential-norm one.
19. [Proposal] Loggerhead sea turtle nest monitoring on seven refuges
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — The purpose of this project is to continue FWS involvement in the long-term, consistent monitoring of loggerhead sea turtle nesting to assess changes in phenological...
20. Shorebird Nesting Success Report : Bear River Migratory Bird Refuge : 2003
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This preliminary study was initiated to establish a baseline of nesting success for one of the most important breeding sites of shorebirds within the Greater Salt...
1. 1982 Bald Eagle Nest Survey, Chesapeake Bay Region.
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Data refers to the 1982 nesting season for the Bald Eagle in the Chesapeake area to include Virginia, Maryland and Delaware. For the third year in succession we have...
2. Black Tern Nesting, Missisquoi National Wildlife Refuge, 2009-2014
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Black tern breeding pair surveys have been conducted in Vermont every year since 1990, except during 2006. Initially, there were 3 separate nesting populations of...
3. Effects Of Predator Exclosures On Nesting Success Of Killdeer
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Nests of shorebirds are often destroyed by predators and in some instances predation may cause severe local declines in breeding success and in size of a breeding...
4. Proposal - Inventory and Monitoring for Red-cockaded Woodpecker Nesting
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Proposal is to monitor the nesting success and productivity of the red-cockaded woodpecker population at the Sam D. Hamilton Noxubee National Wildlife Refuge during...
5. Nesting birds of the Malheur environmental field station
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — The purpose of this paper is to expose the reader to the various birds nesting on the Malheur environmental field station (MEFS). Each species will be discussed...
6. Variation in nesting behavior of eight species of spider mites, Stigmaeopsis having sociality
Science.gov (United States)
Saito, Yutaka; Zhang, Yan-Xuan; Mori, Kotaro; Ito, Katsura; Sato, Yukie; Chittenden, Anthony R.; Lin, Jian-Zhen; Chae, Younghae; Sakagami, Takane; Sahara, Ken
2016-10-01
Nesting behavior is considered to be an important element of social living in animals. The spider mites belonging to the genus Stigmaeopsis spend their lives within nests produced from silk threads. Several of these species show cooperative sociality, while the others are subsocial. In order to identify the origins of this social behavior, comparisons of nest sizes, nesting behaviors (making nests continuously or separately), and their associated traits (fecal deposition patterns) were made for eight cogeneric Stigmaeopsis species showing various levels of social development. All of these species inhabit bamboo plants (Poaceae). We initially addressed the proximate factor of nest size variation. The variation in nest size of the eight species corresponded well with the variation in dorsal seta sc1 length, suggesting that nest size variation among species may have a genetic basis. The time spent within a nest (nest duration) increased with nest size on the respective host plants. Nest arrangement patterns varied among species showing different sized nests: Large nest builders continuously extended their nests, while middle and small nest-building species built new separate nests, which resulted in different social interaction times among species, and is thought to be closely related to social development. Fecal deposition behaviors also varied among Stigmaeopsis species, suggesting diversity in anti-predatory adaptations. Finally, we discuss how the variation in sociality observed within this genus is likely the result of nest size variation that initially evolved as anti-predator strategies.
CERN Document Server
Shcherbakov, Dmitry; Günther, Michael; Finkenrath, Jacob; Knechtli, Francesco; Peardon, Michael
2016-01-01
We study a novel class of numerical integrators, the adapted nested force-gradient schemes, used within the molecular dynamics step of the Hybrid Monte Carlo (HMC) algorithm. We test these methods in the Schwinger model on the lattice, a well known benchmark problem. We derive the analytical basis of nested force-gradient type methods and demonstrate the advantage of the proposed approach, namely reduced computational costs compared with other numerical integration schemes in HMC.
8. Nest sanitation elicits egg discrimination in cuckoo hosts.
Science.gov (United States)
Yang, Canchao; Chen, Min; Wang, Longwu; Liang, Wei; Møller, Anders Pape
2015-11-01
Nest sanitation is a nearly universal behavior in birds, while egg discrimination is a more specific adaptation that has evolved to counter brood parasitism. These two behaviors are closely related with nest sanitation being the ancestral behavior, and it has been hypothesized to constitute a preadaptation for egg discrimination. However, previous studies found little evidence to support this hypothesis. Here, we conducted an empirical test of the association between nest sanitation and egg discrimination in the barn swallow (Hirundo rustica) by inserting a single non-mimetic model egg or a non-mimetic model egg plus half a peanut shell into host nests. Compared to the rejection rate of single model eggs, barn swallows significantly increased egg rejection frequency if a half peanut shell was simultaneously introduced. Our result for the first time shows the impact of nest sanitation on egg discrimination and demonstrates that nest sanitation can elicit egg discrimination in hosts of brood parasites. This study provided evidence for nest sanitation being a preadaptation to egg discrimination by facilitating egg rejection, thereby significantly advancing our understanding of avian cognition of foreign objects. Furthermore, we suggest that egg discrimination behavior in many accepters and intermediate rejecters may be lost or diluted. Such egg discrimination can be elicited and restored after nest sanitation, implying a sensitive and rapid phenotypic response to increased risk of parasitism. Our study offers a novel perspective for investigating the role of so-called intermediate rejecter individuals or species in the long-term coevolutionary cycle between brood parasites and their hosts.
9. Nesting behavior of Podium denticulatum Smith (Hymenoptera: Sphecidae).
Science.gov (United States)
Ribeiro, Favi; Garófalo, Carlos A
2010-01-01
The nesting behavior of Podium denticulatum Smith was studied on the campus of Ribeirão Preto of the Universidade de São Paulo, SP, Brazil, from September 2003 to August 2005. The wasps established their nests in bamboo canes ranging from 11.4 cm to 26.2 cm in length and from 0.7 cm to 1.8 cm in internal diameter. Podium denticulatum nested almost exclusively in the hot and wet season (September-April), producing at least five generations per year. The cell provisioning was made with adult and nymphal cockroaches (Blattellidae) which were arranged venter-up and with the head inward toward the inner end of the cell. The construction of a temporary closure occurred in cells that took more than one day to be provisioned. The cells provisioned with a greater number of prey were more likely to produce females than males. The nests included 1-6 brood cells separated by mud partitions and arranged in a linear series. The innermost cells of the nests produced females, and the outermost cells produced males. Nests were parasitized by Eulophidae (Melittobia sp.), Chrysididae and Tachinidae.
10. Plastic and the nest entanglement of urban and agricultural crows.
Directory of Open Access Journals (Sweden)
Andrea K Townsend
Full Text Available Much attention has been paid to the impacts of plastics and other debris on marine organisms, but the effects of plastic on terrestrial organisms have been largely ignored. Detrimental effects of terrestrial plastic could be most pronounced in intensively human-modified landscapes (e.g., urban and agricultural areas, which are a source of much anthropogenic debris. Here, we examine the occurrence, types, landscape associations, and consequences of anthropogenic nest material in the American crow (Corvus brachyrhynchos, a North American species that breeds in both urban and agricultural landscapes. We monitored 195 nestlings in 106 nests across an urban and agricultural gradient in the Sacramento Valley, California, USA. We found that 85.2% of crow nests contained anthropogenic material, and 11 of 195 nestlings (5.6% were entangled in their nests. The length of the material was greater in nests in agricultural territories than in urban territories, and the odds of entanglement increased 7.55 times for each meter of anthropogenic material in the nest. Fledging success was significantly lower for entangled than for unentangled nestlings. In all environments, particularly urban, agricultural, and marine, careful disposal of potential hazards (string, packing and hay bale twine, balloon ribbon, wire, fishing line could reduce the occurrence of entanglement of nestling birds.
11. Plastic and the nest entanglement of urban and agricultural crows.
Science.gov (United States)
Townsend, Andrea K; Barker, Christopher M
2014-01-01
Much attention has been paid to the impacts of plastics and other debris on marine organisms, but the effects of plastic on terrestrial organisms have been largely ignored. Detrimental effects of terrestrial plastic could be most pronounced in intensively human-modified landscapes (e.g., urban and agricultural areas), which are a source of much anthropogenic debris. Here, we examine the occurrence, types, landscape associations, and consequences of anthropogenic nest material in the American crow (Corvus brachyrhynchos), a North American species that breeds in both urban and agricultural landscapes. We monitored 195 nestlings in 106 nests across an urban and agricultural gradient in the Sacramento Valley, California, USA. We found that 85.2% of crow nests contained anthropogenic material, and 11 of 195 nestlings (5.6%) were entangled in their nests. The length of the material was greater in nests in agricultural territories than in urban territories, and the odds of entanglement increased 7.55 times for each meter of anthropogenic material in the nest. Fledging success was significantly lower for entangled than for unentangled nestlings. In all environments, particularly urban, agricultural, and marine, careful disposal of potential hazards (string, packing and hay bale twine, balloon ribbon, wire, fishing line) could reduce the occurrence of entanglement of nestling birds.
12. Nesting biology of Centris (Centris aenea Lepeletier (Hymenoptera, Apidae, Centridini
Directory of Open Access Journals (Sweden)
Cândida Maria Lima Aguiar
2003-12-01
Full Text Available Nesting activity of Centris aenea Lepeletier, 1841 was studied in two Brazilian habitats, Caatinga (Monte Santo, Bahia and Cerrado (Palmeiras, Bahia and Luiz Antônio, São Paulo. Nests were excavated in the ground and did not tend to be aggregated together at the two sites, but at Palmeiras, nests were in a large aggregation. Nest architecture consists of a single unbranched tunnel, sloping to vertical, which leads to a linear series of four cells, placed from 8 to 26 cm in depth. Cells are urn-shaped with a rounded base, and their cell caps have a central hollow process, as in other Centridini. Nest architecture of C. aenea was compared to other species of Centris Fabricius, 1804. Provisions are composed of a pollen mass covered by a thin liquid layer on which the egg is placed. Females were observed gathering oil on Mcvaughia bahiana W.R. Anderson flowers from October to March in the Caatinga, and on Byrsonima intermedia A.Juss. as well as other Malpighiaceae species from August to December in the Cerrado. Pollen is gathered by buzzing flowers of Solanaceae, Caesalpiniaceae, Malpighiaceae, and Ochnaceae. Several nectar sources were recorded. There is indirect evidence that Mesoplia sp. parasitizes nests of C. aenea in the Cerrado.
13. Japanese queenless ants, Pristomyrmex punctatus, prefer the traces of both nestmates and strangers in nest selection.
Science.gov (United States)
Satow, Show; Saitow, Yuka; Yamaki, Shōtarō; Hirota, Tadao
2013-07-01
Conspecific avoidance may influence the spatial distribution of colonies in some ants. House-hunting ants (Temnothorax albipennis) avoid nesting in areas where non-nestmates have nested previously. However, no reports are available on conspecific avoidance during nest selection in other ants. In the present study, we investigated nest selection in another nomadic species, the Japanese queenless ant, Pristomyrmex punctatus. Two-choice tests revealed that, similar to house-hunting ants, P. punctatus preferred nests soiled by nestmates to clean nests. However, unlike house-hunting ants, P. punctatus also preferred nests soiled by non-nestmates to a clean nest. Given the choice between a nest soiled by nestmates and one soiled by strangers, P. punctatus, unlike house-haunting ants, showed no significant preference. Thus, conspecific avoidance in nest selection was not observed in P. punctatus. Interspecific differences in ecological factors may drive the evolution of different nest selection strategies.
14. Striped-tailed Yellow-finch nesting success in abandoned mining pits from central Brazilian cerrado
Directory of Open Access Journals (Sweden)
DT. Gressler
Full Text Available Suitability of degraded areas as breeding habitats can be tested through assessment of nest predation rates. In this study we estimated nest success in relation to several potential predictors of nest survival in the Stripe-tailed Yellow-finch (Sicalis citrina breeding in abandoned mining pits at Brasília National Park. We monitored 73 nests during the 2007-breeding season. Predation was the main cause of nest failure (n = 48, 66%; while six nests were abandoned (8% and 19 nests produced young (26%. Mayfield’s daily survival rates and nest success were 0.94 and 23%, respectively. Our results from nest survival models on program MARK indicated that daily survival rates increase linearly towards the end of the breeding season and decrease as nests aged. None of the nest individual covariates we tested - nest height, nest size, nest substrate, and edge effect - were important predictors of nest survival; however, nests placed on the most common plant tended to have higher survival probabilities. Also, there was no observer effect on daily survival rates. Our study suggests that abandoned mining pits may be suitable alternative breeding habitats for Striped-tailed Yellow-finches since nest survival rates were similar to other studies in the central cerrado region.
15. A review of the nest protection hypothesis: does inclusion of fresh green plant material in birds' nests reduce parasite infestation?
Science.gov (United States)
Scott-Baumann, James F; Morgan, Eric R
2015-07-01
The use of aromatic plants and their essential oils for ectoparasite treatment is a field of growing interest. Several species of birds regularly introduce aromatic herbs into their nests putatively to reduce parasites. The behaviour is most often seen in cavity nesting birds and after nest building has finished. The plants are included in a non-structural manner and are often strongly aromatic. Various different hypotheses have been proposed regarding the function of this behaviour; from the plants altering some non-living factor in the nest (crypsis, water loss and insulation hypotheses) to them being involved in mate selection (mate hypothesis) or even having a beneficial effect, direct or indirect, on chicks (drug or nest protection hypothesis, NPH). Many studies have been carried out over the years observing and experimentally testing these hypotheses. This review focuses on studies involving the most popular of these hypotheses, the NPH: that plants decrease nest parasites or pathogens, thereby conveying positive effects to the chicks, allowing the behaviour to evolve. Studies providing observational evidence towards this hypothesis and those experimentally testing it are discussed.
16. Variation in clutch size in relation to nest size in birds
Science.gov (United States)
Møller, Anders P; Adriaensen, Frank; Artemyev, Alexandr; Bańbura, Jerzy; Barba, Emilio; Biard, Clotilde; Blondel, Jacques; Bouslama, Zihad; Bouvier, Jean-Charles; Camprodon, Jordi; Cecere, Francesco; Charmantier, Anne; Charter, Motti; Cichoń, Mariusz; Cusimano, Camillo; Czeszczewik, Dorota; Demeyrier, Virginie; Doligez, Blandine; Doutrelant, Claire; Dubiec, Anna; Eens, Marcel; Eeva, Tapio; Faivre, Bruno; Ferns, Peter N; Forsman, Jukka T; García-Del-Rey, Eduardo; Goldshtein, Aya; Goodenough, Anne E; Gosler, Andrew G; Góźdź, Iga; Grégoire, Arnaud; Gustafsson, Lars; Hartley, Ian R; Heeb, Philipp; Hinsley, Shelley A; Isenmann, Paul; Jacob, Staffan; Järvinen, Antero; Juškaitis, Rimvydas; Korpimäki, Erkki; Krams, Indrikis; Laaksonen, Toni; Leclercq, Bernard; Lehikoinen, Esa; Loukola, Olli; Lundberg, Arne; Mainwaring, Mark C; Mänd, Raivo; Massa, Bruno; Mazgajski, Tomasz D; Merino, Santiago; Mitrus, Cezary; Mönkkönen, Mikko; Morales-Fernaz, Judith; Morin, Xavier; Nager, Ruedi G; Nilsson, Jan-Åke; Nilsson, Sven G; Norte, Ana C; Orell, Markku; Perret, Philippe; Pimentel, Carla S; Pinxten, Rianne; Priedniece, Ilze; Quidoz, Marie-Claude; Remeš, Vladimir; Richner, Heinz; Robles, Hugo; Rytkönen, Seppo; Senar, Juan Carlos; Seppänen, Janne T; da Silva, Luís P; Slagsvold, Tore; Solonen, Tapio; Sorace, Alberto; Stenning, Martyn J; Török, János; Tryjanowski, Piotr; van Noordwijk, Arie J; von Numers, Mikael; Walankiewicz, Wiesław; Lambrechts, Marcel M
2014-01-01
Nests are structures built to support and protect eggs and/or offspring from predators, parasites, and adverse weather conditions. Nests are mainly constructed prior to egg laying, meaning that parent birds must make decisions about nest site choice and nest building behavior before the start of egg-laying. Parent birds should be selected to choose nest sites and to build optimally sized nests, yet our current understanding of clutch size-nest size relationships is limited to small-scale studies performed over short time periods. Here, we quantified the relationship between clutch size and nest size, using an exhaustive database of 116 slope estimates based on 17,472 nests of 21 species of hole and non-hole-nesting birds. There was a significant, positive relationship between clutch size and the base area of the nest box or the nest, and this relationship did not differ significantly between open nesting and hole-nesting species. The slope of the relationship showed significant intraspecific and interspecific heterogeneity among four species of secondary hole-nesting species, but also among all 116 slope estimates. The estimated relationship between clutch size and nest box base area in study sites with more than a single size of nest box was not significantly different from the relationship using studies with only a single size of nest box. The slope of the relationship between clutch size and nest base area in different species of birds was significantly negatively related to minimum base area, and less so to maximum base area in a given study. These findings are consistent with the hypothesis that bird species have a general reaction norm reflecting the relationship between nest size and clutch size. Further, they suggest that scientists may influence the clutch size decisions of hole-nesting birds through the provisioning of nest boxes of varying sizes. PMID:25478150
17. Social waves in giant honeybees (Apis dorsata) elicit nest vibrations.
Science.gov (United States)
Kastberger, Gerald; Weihmann, Frank; Hoetzl, Thomas
2013-07-01
Giant honeybees (Apis dorsata) nest in the open and have developed a wide array of strategies for colony defence, including the Mexican wave-like shimmering behaviour. In this collective response, the colony members perform upward flipping of their abdomens in coordinated cascades across the nest surface. The time-space properties of these emergent waves are response patterns which have become of adaptive significance for repelling enemies in the visual domain. We report for the first time that the mechanical impulse patterns provoked by these social waves and measured by laser Doppler vibrometry generate vibrations at the central comb of the nest at the basic (='natural') frequency of 2.156 ± 0.042 Hz which is more than double the average repetition rate of the driving shimmering waves. Analysis of the Fourier spectra of the comb vibrations under quiescence and arousal conditions provoked by mass flight activity and shimmering waves gives rise to the proposal of two possible models for the compound physical system of the bee nest: According to the elastic oscillatory plate model, the comb vibrations deliver supra-threshold cues preferentially to those colony members positioned close to the comb. The mechanical pendulum model predicts that the comb vibrations are sensed by the members of the bee curtain in general, enabling mechanoreceptive signalling across the nest, also through the comb itself. The findings show that weak and stochastic forces, such as general quiescence or diffuse mass flight activity, cause a harmonic frequency spectrum of the comb, driving the comb as an elastic plate. However, shimmering waves provide sufficiently strong forces to move the nest as a mechanical pendulum. This vibratory behaviour may support the colony-intrinsic information hypothesis herein that the mechanical vibrations of the comb provoked by shimmering do have the potential to facilitate immediate communication of the momentary defensive state of the honeybee nest to
18. Reproductive ecology of American Oystercatchers nesting on shell rakes
Science.gov (United States)
Jodice, Patrick G.; Thibault, Janet M.; Collins, S.A.; Spinks, Mark D.; Sanders, Felicia J.
2014-01-01
Degradation of nesting habitat for coastal birds has led to the use of nontraditional nesting habitat. The American Oystercatcher (Haematopus palliatus) is listed as a "Species of High Concern'' by the U. S. Shorebird Conservation Plan and is declining in the southern portion of its U. S. breeding range, where ~ 50% of breeding oystercatchers nest on shell substrate instead of beachfront habitat. We measured daily survival rates during incubation and chick rearing in shell rake habitats over five breeding seasons in the Cape Romain region of South Carolina, USA. Of 354 nesting attempts monitored, 16.1% hatched at least one egg. During incubation, daily survival rate was 0.938, corresponding to 22.8% success to hatching (nest success). For broods, daily survival was 0.991, or 74.0% success from hatching to fledging. Productivity in the Cape Romain region is primarily being lost during the incubation phase, when nests are exposed to overwash and predation. Mobile chicks may, however, be able to avoid flood events or predators by relocating to higher or more protected portions of a shell rake. Based on comparative data for American Oystercatchers from elsewhere in their range, it does not appear that shell rakes in the Cape Romain region are inferior breeding habitat. Our data suggest that conservation actions targeting nest and chick loss from flooding and predation have the greatest opportunity to enhance reproductive success in this core breeding area, and that an assessment of the availability, structure, avian use, and protection status of shell rakes is warranted.
19. Is it safe to nest near conspicuous neighbours? Spatial patterns in predation risk associated with the density of American Golden-Plover nests
Directory of Open Access Journals (Sweden)
Marie-Andrée Giroux
2016-08-01
Full Text Available Predation is one of the main factors explaining nesting mortality in most bird species. Birds can avoid nest predation or reduce predation pressure by breeding at higher latitude, showing anti-predator behaviour, selecting nest sites protected from predators, and nesting in association with protective species. American Golden-Plovers (Pluvialis dominica defend their territory by using various warning and distraction behaviours displayed at varying levels of intensity (hereafter “conspicuous behaviour”, as well as more aggressive behaviours such as aerial attacks, but only in some populations. Such antipredator behaviour has the potential to repel predators and thus benefit the neighbouring nests by decreasing their predation risk. Yet, conspicuous behaviour could also attract predators by signalling the presence of a nest. To test for the existence of a protective effect associated with the conspicuous antipredator behaviour of American Golden-Plovers, we studied the influence of proximity to plover nests on predation risk of artificial nests on Igloolik Island (Nunavut, Canada in July 2014. We predicted that the predation risk of artificial nests would decrease with proximity to and density of plover nests. We monitored 18 plover nests and set 35 artificial nests at 30, 50, 100, 200, and 500 m from seven of those plover nests. We found that the predation risk of artificial nests increases with the density of active plover nests. We also found a significant negative effect of the distance to the nearest active protector nest on predation risk of artificial nests. Understanding how the composition and structure of shorebird communities generate spatial patterns in predation risks represents a key step to better understand the importance of these species of conservation concern in tundra food webs.
20. Variation in clutch size in relation to nest size in birds
NARCIS (Netherlands)
Møller, Anders P.; Adriaensen, Frank; Artemyev, Alexandr; Bańbura, Jerzy; Barba, Emilio; Biard, Clotilde; Blondel, Jacques; Bouslama, Zihad; Bouvier, Jean-Charles; Camprodon, Jordi; Cecere, Francesco; Charmantier, Anne; Charter, Motti; Cichoń, Mariusz; Cusimano, Camillo; Czeszczewik, Dorota; Demeyrier, Virginie; Doligez, Blandine; Doutrelant, Claire; Dubiec, Anna; Eens, Marcel; Eeva, Tapio; Faivre, Bruno; Ferns, Peter N.; Forsman, Jukka T.; García-Del-Rey, Eduardo; Goldshtein, Aya; Goodenough, Anne E.; Gosler, Andrew G.; Góźdź, Iga; Grégoire, Arnaud; Gustafsson, Lars; Hartley, Ian R.; Heeb, Philipp; Hinsley, Shelley A.; Isenmann, Paul; Jacob, Staffan; Järvinen, Antero; Juškaitis, Rimvydas; Korpimäki, Erkki; Krams, Indrikis; Laaksonen, Toni; Leclercq, Bernard; Lehikoinen, Esa; Loukola, Olli; Lundberg, Arne; Mainwaring, Mark C.; Mänd, Raivo; Massa, Bruno; Mazgajski, Tomasz D.; Merino, Santiago; Mitrus, Cezary; Mönkkönen, Mikko; Morales-Fernaz, Judith; Morin, Xavier; Nager, Ruedi G.; Nilsson, Jan-Åke; Nilsson, Sven G.; Norte, Ana C.; Orell, Markku; Perret, Philippe; Pimentel, Carla S.; Pinxten, Rianne; Priedniece, Ilze; Quidoz, Marie-Claude; Remeš, Vladimir; Richner, Heinz; Robles, Hugo; Rytkönen, Seppo; Senar, Juan Carlos; Seppänen, Janne T.; da Silva, Luís P.; Slagsvold, Tore; Solonen, Tapio; Sorace, Alberto; Stenning, Martyn J.; Török, János; Tryjanowski, Piotr; van Noordwijk, Arie J.; von Numers, Mikael; Walankiewicz, Wiesław; Lambrechts, Marcel M.
2014-01-01
Nests are structures built to support and protect eggs and/or offspring from predators, parasites, and adverse weather conditions. Nests are mainly constructed prior to egg laying, meaning that parent birds must make decisions about nest site choice and nest building behavior before the start of
1. Predicting nest success from habitat features in aspen forests of the central Rocky Mountains
Science.gov (United States)
Heather M. Struempf; Deborah M. Finch; Gregory Hayward; Stanley Anderson
2001-01-01
We collected nesting data on bird use of aspen stands in the Routt and Medicine Bow National Forests between 1987 and 1989. We found active nest sites of 28 species of small nongame birds on nine study plots in undisturbed aspen forests. We compared logistic regression models predicting nest success (at least one nestling) from nest-site or stand-level habitat...
2. Male Rock Sparrow (Petronia petronia) Nest Defence Correlates with Female Ornament Size
DEFF Research Database (Denmark)
Griggio, Matteo; Matessi, Giuliano; Pilastro, Andrea
2003-01-01
We investigated the relationship between male nest defence and female breast patch size in an alpine population of rock sparrow (Petronia petronia) in northern Italy. We presented a mounted weasel (Mustela nivalis), a common nest predator, to 28 pairs breeding in nest boxes, with 12-13-d-old nest...
3. Breeding phenology of birds: mechanisms underlying seasonal declines in the risk of nest predation.
Directory of Open Access Journals (Sweden)
Kathi L Borgmann
Full Text Available Seasonal declines in avian clutch size are well documented, but seasonal variation in other reproductive parameters has received less attention. For example, the probability of complete brood mortality typically explains much of the variation in reproductive success and often varies seasonally, but we know little about the underlying cause of that variation. This oversight is surprising given that nest predation influences many other life-history traits and varies throughout the breeding season in many songbirds. To determine the underlying causes of observed seasonal decreases in risk of nest predation, we modeled nest predation of Dusky Flycatchers (Empidonax oberholseri in northern California as a function of foliage phenology, energetic demand, developmental stage, conspecific nest density, food availability for nest predators, and nest predator abundance. Seasonal variation in the risk of nest predation was not associated with seasonal changes in energetic demand, conspecific nest density, or predator abundance. Instead, seasonal variation in the risk of nest predation was associated with foliage density (early, but not late, in the breeding season and seasonal changes in food available to nest predators. Supplemental food provided to nest predators resulted in a numerical response by nest predators, increasing the risk of nest predation at nests that were near supplemental feeders. Our results suggest that seasonal changes in foliage density and factors associated with changes in food availability for nest predators are important drivers of temporal patterns in risk of avian nest predation.
4. Assessing nest-building behavior of mice using a 3D depth camera.
Science.gov (United States)
Okayama, Tsuyoshi; Goto, Tatsuhiko; Toyoda, Atsushi
2015-08-15
We developed a novel method to evaluate the nest-building behavior of mice using an inexpensive depth camera. The depth camera clearly captured nest-building behavior. Using three-dimensional information from the depth camera, we obtained objective features for assessing nest-building behavior, including "volume," "radius," and "mean height". The "volume" represents the change in volume of the nesting material, a pressed cotton square that a mouse shreds and untangles in order to build its nest. During the nest-building process, the total volume of cotton fragments is increased. The "radius" refers to the radius of the circle enclosing the fragments of cotton. It describes the extent of nesting material dispersion. The "radius" averaged approximately 60mm when a nest was built. The "mean height" represents the change in the mean height of objects. If the nest walls were high, the "mean height" was also high. These features provided us with useful information for assessment of nest-building behavior, similar to conventional methods for the assessment of nest building. However, using the novel method, we found that JF1 mice built nests with higher walls than B6 mice, and B6 mice built nests faster than JF1 mice. Thus, our novel method can evaluate the differences in nest-building behavior that cannot be detected or quantified by conventional methods. In future studies, we will evaluate nest-building behaviors of genetically modified, as well as several inbred, strains of mice, with several nesting materials.
5. Correlates of nest-defense behavior of common terns
Science.gov (United States)
Erwin, R.M.
1988-01-01
Nest-defense behavior was studied at seven Common Tern (Sterna hirundo) colonies in southern coastal New Jersey during June and July 1981. Data were collected weekly on numbers of adults, nests, eggs, and young in relation to the frequency and intensity of dive attacks on a human intruder by nesting terns. I explored the relationships between attack behavior and colony size/density, seasonality, and brood survival. The results provide little support for social facilitation since neither colony size (range 30-250 nests) nor density was related to mean attack frequency; however, in larger colonies, fewer birds participated in dive attacks. Although the intensity of attacks was strongly seasonal, patterns were very different among colonies and peak attack rates did not always coincide with peak hatching periods. Defense levels declined late in the season in most colonies regardless of whether brood survival was high or low. Colonies with individuals that attacked early in the season had higher overall nesting success than in colonies where individuals showed little early season aggression.
6. Commitments to aggression and nest sites in male Betta splendens.
Science.gov (United States)
Bronstein, P M
1981-06-01
Male Siamese fighting fish construct nests that are relatively isolated from conspecific males. Following nest construction, the presence of a male opponent elicits (a) nest fixation, (b) further nest building, and (c) Betta's agonistic sequence, i.e., attacks alternating with flight movements, along with gill displays occurring near the opponent. The form of a male-male encounter depends upon the distance between a resident's nest and the opponent as well as upon the individual differences in combatants' tolerance for the presence of a conspecific nearby. Also, the intensity of aggression early in an encounter is positively correlated with the intensity of subsequent fighting. Male Bettas appear to compete for space through the use of aggressive behavior and to coordinate their fighting activities by means of visual signals. An incentive model of visual communication is proposed in which visual cues emanating from a displaying male opponent elicit attack with an intensity that is directly proportional to the persistence of the opponent and inversely proportional to the distance between fish.
7. Hydrodynamic modeling of Singapore's coastal waters: Nesting and model accuracy
Science.gov (United States)
Hasan, G. M. Jahid; van Maren, Dirk Sebastiaan; Ooi, Seng Keat
2016-01-01
The tidal variation in Singapore's coastal waters is influenced by large-scale, complex tidal dynamics (by interaction of the Indian Ocean and the South China Sea) as well as monsoon-driven low frequency variations, requiring a model with large spatial coverage. Close to the shores, the complex topography, influenced by headlands and small islands, requires a high resolution model to simulate tidal dynamics. This can be achieved through direct nesting or multi-scale nesting, involving multiple model grids. In this paper, we investigate the effect of grid resolution and multi-scale nesting on the tidal dynamics in Singapore's coastal waters, by comparing model results with observations using different statistical techniques. The results reveal that the intermediate-scale model is generally sufficiently accurate (equal to or better than the most refined model), but also that the most refined model is only more accurate when nested in the intermediate scale model (requiring multi-scale nesting). This latter is the result of the complex tidal dynamics around Singapore, where the dominantly diurnal tidal currents are decoupled from the semi-diurnal water level variations. Furthermore, different techniques to quantify model accuracy (harmonic analysis, basic statistics and more complex statistics) are inconsistent in determining which model is more accurate.
8. Does habitat fragmentation influence nest predation in the shortgrass prairie?
Science.gov (United States)
Howard, M.N.; Skagen, S.K.; Kennedy, P.L.
2001-01-01
We examined the effects of habitat fragmentation and vegetation structure of shortgrass prairie and Conservation Reserve Program (CRP) lands on predation rates of artificial and natural nests in northeastern Colorado. The CRP provides federal payments to landowners to take highly erodible cropland out of agricultural production. In our study area, CRP lands have been reseeded primarily with non-native grasses, and this vegetation is taller than native shortgrass prairie. We measured three indices of habitat fragmentation (patch size, degree of matrix fragmentation, and distance from edge), none of which influenced mortality rates of artificial or natural nests. Vegetation structure did influence predation rates of artificial nests; daily mortality decreased significantly with increasing vegetation height. Vegetation structure did not influence predation rates of natural nests. CRP lands and shortgrass sites did not differ with respect to mortality rates of artificial nests. Our study area is only moderately fragmented; 62% of the study area is occupied by native grassland. We conclude that the extent of habitat fragmentation in our study area does not result in increased predation in remaining patches of shortgrass prairie habitat.
9. Homing to nest baskets by wild female mallards
Science.gov (United States)
Doty, H.A.; Lee, F.B.
1974-01-01
10. Lifespan analyses of forest raptor nests: patterns of creation, persistence and reuse.
Science.gov (United States)
Jiménez-Franco, María V; Martínez, José E; Calvo, José F
2014-01-01
Structural elements for breeding such as nests are key resources for the conservation of bird populations. This is especially true when structural elements require a specific and restricted habitat, or if the construction of nests is costly in time and energy. The availability of nesting-platforms is influenced by nest creation and persistence. In a Mediterranean forest in southeastern Spain, nesting-platforms are the only structural element for three forest-dwelling raptor species: booted eagle Aquila pennata, common buzzard Buteo buteo and northern goshawk Accipiter gentilis. From 1998 to 2013, we tracked the fate of 157 nesting-platforms built and reused by these species with the aim of determining the rates of creation and destruction of nesting-platforms, estimating nest persistence by applying two survival analyses, describing the pattern of nest reuse and testing the effects of nest use on breeding success. Nest creation and destruction rates were low (0.14 and 0.05, respectively). Using Kaplan Meier survival estimates and Cox proportional-hazards regression models we found that median nest longevity was 12 years and that this was not significantly affected by nest characteristics, nest-tree dimensions, nest-builder species, or frequency of use of the platform. We also estimated a transition matrix, considering the different stages of nest occupation (vacant or occupied by one of the focal species), to obtain the fundamental matrix and the average life expectancies of nests, which varied from 17.9 to 19.7 years. Eighty six percent of nests were used in at least one breeding attempt, 67.5% were reused and 17.8% were successively occupied by at least two of the study species. The frequency of nest use had no significant effects on the breeding success of any species. We conclude that nesting-platforms constitute an important resource for forest raptors and that their longevity is sufficiently high to allow their reuse in multiple breeding attempts.
11. Exploring Multi-Modal Distributions with Nested Sampling
CERN Document Server
Feroz, F
2013-01-01
In performing a Bayesian analysis, two difficult problems often emerge. First, in estimating the parameters of some model for the data, the resulting posterior distribution may be multi-modal or exhibit pronounced (curving) degeneracies. Secondly, in selecting between a set of competing models, calculation of the Bayesian evidence for each model is computationally expensive using existing methods such as thermodynamic integration. Nested Sampling is a Monte Carlo method targeted at the efficient calculation of the evidence, but also produces posterior inferences as a by-product and therefore provides means to carry out parameter estimation as well as model selection. The main challenge in implementing Nested Sampling is to sample from a constrained probability distribution. One possible solution to this problem is provided by the Galilean Monte Carlo (GMC) algorithm. We show results of applying Nested Sampling with GMC to some problems which have proven very difficult for standard Markov Chain Monte Carlo (MC...
12. Characterising equilibrium logic and nested logic programs: Reductions and complexity
CERN Document Server
Pearce, David; Woltran, Stefan
2009-01-01
Equilibrium logic is an approach to nonmonotonic reasoning that extends the stable-model and answer-set semantics for logic programs. In particular, it includes the general case of nested logic programs, where arbitrary Boolean combinations are permitted in heads and bodies of rules, as special kinds of theories. In this paper, we present polynomial reductions of the main reasoning tasks associated with equilibrium logic and nested logic programs into quantified propositional logic, an extension of classical propositional logic where quantifications over atomic formulas are permitted. We provide reductions not only for decision problems, but also for the central semantical concepts of equilibrium logic and nested logic programs. In particular, our encodings map a given decision problem into some formula such that the latter is valid precisely in case the former holds. The basic tasks we deal with here are the consistency problem, brave reasoning, and skeptical reasoning. Additionally, we also provide encoding...
13. Nest architecture shapes the collective behaviour of harvester ants.
Science.gov (United States)
Pinter-Wollman, Noa
2015-10-01
Structures influence how individuals interact and, therefore, shape the collective behaviours that emerge from these interactions. Here I show that the structure of a nest influences the collective behaviour of harvester ant colonies. Using network analysis, I quantify nest architecture and find that as chamber connectivity and redundancy of connections among chambers increase, so does a colony's speed of recruitment to food. Interestingly, the volume of the chambers did not influence speed of recruitment, suggesting that the spatial organization of a nest has a greater impact on collective behaviour than the number of workers it can hold. Thus, by changing spatial constraints on social interactions organisms can modify their behaviour and impact their fitness.
14. Welfare indicators in laying hens in relation to nest exclusion
DEFF Research Database (Denmark)
Alm, M; Tauson, R; Holm, L
2016-01-01
. The assessed indicators were: corticosterone metabolites in droppings (FCM), corticosterone concentration in yolk, corticosterone concentration in plasma, irregularities of eggshells, heterophil to lymphocyte (H:L) ratio, tonic immobility duration, and feather cover. Behavioral observations showed...... that the birds had a clear preference for using the secluded nest sites, confirming that they were likely to perceive nest exclusion as an undesirable experience. Further, elevated levels of FCM in droppings, yolk corticosterone concentrations, H:L ratios and irregular eggshells were detected in both nest...... between FCM in droppings and eggshell irregularities, also supporting the use of eggshell irregularities as a potential non-invasive welfare indicator. However, the pattern of the stress response varied between indicators and correlations were generally few and inconsistent, highlighting the complexity...
15. Factors affecting detection of burrowing owl nests during standardized surveys
Science.gov (United States)
Conway, C.J.; Garcia, V.; Smith, M.D.; Hughes, K.
2008-01-01
Identifying causes of declines and evaluating effects of management practices on persistence of local populations of burrowing owls (Athene cunicularia) requires accurate estimates of abundance and population trends. Moreover, regulatory agencies in the United States and Canada typically require surveys to detect nest burrows prior to approving developments or other activities in areas that are potentially suitable for nesting burrowing owls. In general, guidelines on timing of surveys have been lacking and surveys have been conducted at different times of day and in different stages of the nesting cycle. We used logistic regression to evaluate 7 factors that could potentially affect probability of a surveyor detecting a burrowing owl nest. We conducted 1,444 detection trials at 323 burrowing owl nests within 3 study areas in Washington and Wyoming, USA, between February and August 2000-2002. Detection probability was highest during the nestling period and increased with ambient temperature. The other 5 factors that we examined (i.e., study area, time of day, timing within the breeding season, wind speed, % cloud cover) interacted with another factor to influence detection probability. Use of call-broadcast surveys increased detection probability, even during daylight hours when we detected >95% of owls visually. Optimal timing of surveys will vary due to differences in breeding phenology and differences in nesting behavior across populations. Nevertheless, we recommend ???3 surveys per year: one that coincides with the laying and incubation period, another that coincides with the early nestling period, and a third that coincides with the late nestling period. In northern latitudes, surveys can be conducted throughout the day.
16. Small suburban cities of Lille Metropolis for the well-being of metropolitan? / Les petites villes periurbaines de la metropole lilloise au service du bien-etre des metropolitains?
Directory of Open Access Journals (Sweden)
Laurène Wiesztort
2016-09-01
Full Text Available Cities, main biotope of the Man in the World, glean more and more agricultural lands and natural spaces beyond the distant peripheries. Historic processes such as the mass urbanization or the industrialization based on the exploitation of subsoil resources, have taken over many natural spaces that were destroyed or erased or exploited for economic purposes. The region Nord Pas-de-Calais (France has a rate of arti cialisation of the very high ground, it’s fragmented territory and upset by two world con icts and a intense mining period. So, today, meadows of three quarter of peoples of the region consider that there isn’t enough nature in the heart of their city. Within the framework of the métropolisation, this feeling is accentuated due to urban sprawl, which is more and more important. Since the 1990s, we speak about sustainable development as about a new philosophy that would lead us to a more balanced world between will economic, social, cultural and environmental policies. The region is very invested in the domain, because of the speci cities of its territory. The objective of this investigation was to account for forms that can take the environmental territorial policies and / or whose issues the welfare of citizens through new recreational spaces in nature. Are small towns “used” to ll the void nature of large cities ?. Methodologically, I have chosen to address this issue by studying the case of Lille Metropolis, relying on both eldwork four years during my thesis as well as on two inquiries which I led on the regional territory in 2006 and 2011. This research has helped to highlight the medium-sized cities, small towns and rural municipalities play a major role in territorial policies such as green and blue weft. They are the key to meet the demand of urban natural spaces. Taking this into consideration, the region will thinking about the nature of hearts with many vocations: ecological (biodiversity reserves, social (parks and
17. Fleas (Siphonaptera) in the Nests of Dormice (Gliridae: Rodentia) in Lithuania.
Science.gov (United States)
Lipatova, I; Stanko, M; Paulauskas, A; Spakovaite, S; Gedminas, V
2015-05-01
Negative effects of flea (Siphonaptera) parasitism on the host may be expressed in different ways. The aim of this study was to assess distribution of the flea fauna in nests of dormice in Lithuania. Nests of Glis glis (L.), Dryomys nitedula (Pallas), and Muscardinus avellanarius (L.) were collected from nest boxes in 2012 and 2013. Fleas were collected from nests in the laboratory and put into plastic tubes with 70% ethanol. Flea species were identified using morphological keys. From 400 nest boxes, 112 nests of dormice were collected from eight sites from mixed forests of central Lithuania. Twenty-three nests of G. glis were collected from nest boxes, with 16 of them containing 286 fleas belonging to four species: Ceratophyllus sciurorum (Schrank) (259), C. gallinae (Schrank) (23), Hystrichopsylla talpae (Curtis) (3), and Megabothris turbidus (Rothschild) (1). Fourteen nests of M. avellanarius were collected from nest boxes, 4 of which contained 224 fleas belonging to two species: C. sciurorum (221) and C. gallinae (3). Twenty-four nests of D. nitedula were collected from nest boxes, including 17 containing 207 fleas belonging to two species: C. sciurorum (205) and C. gallinae (2). Fifty-one nests of undetermined dormice species also were collected from nest boxes, 12 of them contained 395 fleas belonging to three species: C. sciurorum (374), Ctenophthalmus agyrtes (Heller) (19), and Ctenophthalmus assimilis (Taschenberg) (2). C. sciurorum was a predominant species in the nests of dormice. The occurrence of C. gallinae was documented in Lithuania for the first time.
18. Coping with shifting nest predation refuges by European reed Warblers Acrocephalus scirpaceus.
Directory of Open Access Journals (Sweden)
Lucyna Halupka
Full Text Available Predation, the most important source of nest mortality in altricial birds, has been a subject of numerous studies during past decades. However, the temporal dynamics between changing predation pressures and parental responses remain poorly understood. We analysed characteristics of 524 nests of European reed warblers monitored during six consecutive breeding seasons in the same area, and found some support for the shifting nest predation refuge hypothesis. Nest site characteristics were correlated with nest fate, but a nest with the same nest-site attributes could be relatively safe in one season and vulnerable to predation in another. Thus nest predation refuges were ephemeral and there was no between-season consistency in nest predation patterns. Reed warblers that lost their first nests in a given season did not disperse farther for the subsequent reproductive attempt, compared to successful individuals, but they introduced more changes to their second nest sites. In subsequent nests, predation risk remained constant for birds that changed nest-site characteristics, but increased for those that did not. At the between-season temporal scale, individual birds did not perform better with age in terms of reducing nest predation risk. We conclude that the experience acquired in previous years may not be useful, given that nest predation refuges are not stable.
19. Pseudoxylaria as stowaway of the fungus-growing termite nest:
DEFF Research Database (Denmark)
Visser, Anna A.; Kooij, Pepijn Wilhelmus; Debets, Alfons J. M.
2011-01-01
Though inconspicuous in healthy nests, Pseudoxylaria species are almost always present and overgrow deteriorating fungus-growing termite gardens. Whether these fungi are detrimental to the fungus-garden, benign, or even beneficial is unclear. We hypothesize that Pseudoxylaria is a stowaway...... that practices a sit-and-wait strategy to survive in the termite nest. Using isolates from three different termite genera to test our hypothesis, we compared Pseudoxylaria’s growth on 40 carbon sources with that of Termitomyces and tested its interaction with Termitomyces. The C-source use of both fungi largely...
20. Imperfect nesting and transport properties in unconventional density waves
Science.gov (United States)
Dóra, Balázs; Maki, Kazumi; Virosztek, Attila
2002-10-01
We consider the effect of imperfect nesting in quasi-one-dimensional unconventional density waves (DW's). The phase diagram is very close to those in a conventional DW's. The linear and non-linear aspects of the electric conductivity are discussed. At T=0 the frequency dependent electric conductivity develops a small dip at low frequencies. The threshold electric field depends strongly on the imperfect nesting parameter, allowing us to describe very well the measured threshold electric field in the low temperature phase of the quasi-two-dimensional organic conductor, α-(BEDT-TTF)2KHg(SCN)4.
1. Efficient use of iterative solvers in nested topology optimization
DEFF Research Database (Denmark)
Amir, Oded; Stolpe, Mathias; Sigmund, Ole
2010-01-01
In the nested approach to structural optimization, most of the computational effort is invested in the solution of the analysis equations. In this study, it is suggested to reduce this computational cost by using an approximation to the solution of the analysis problem, generated by a Krylov...... subspace iterative solver. By choosing convergence criteria for the iterative solver that are strongly related to the optimization objective and to the design sensitivities, it is possible to terminate the iterative solution of the nested equations earlier compared to traditional convergence measures...
2. Don't Mess with the NEST
Energy Technology Data Exchange (ETDEWEB)
Larson, M
2012-03-15
NEST stands for Nuclear Emergency Support Team. The NEST Mission Statement as first established: (1) Conduct, direct, coordinate search and recovery operations for nuclear material, weapons or devices; and (2) Assist in identification and deactivation of Improvised Nuclear Devices (INDs) and Radiological Dispersal Devices (RDDs). Then in 1980 a very sophisticated improvised explosive device was found at Harvey's Casino at Lake Tahoe, Nevada. The FBI and Bomb Squads were unprepared and it detonated. As a result the additional phrase 'and Sophisticated Improvised Explosive Devices (SIEDs)' was added to the Mission Statement.
3. Must lill heidab suure varju / Andres Laasik
Index Scriptorium Estoniae
Laasik, Andres, 1960-2016
2007-01-01
Brian De Palma krimimüsteerium "Must daalia" ("The Black Dahlia"), mis põhineb James Ellroy samanimelisel romaanil : operaator Vilmos Zsigmond : osades Josh Hartnett, Aaron Eckhart, Hilary Swank, Scarlett Johansson : Ameerika Ühendriigid 2006. Film noir'i stilistika kasutamisest filmis
4. Kan naturvidenskaben forklare den lille forskel?
DEFF Research Database (Denmark)
Sørensen, Astrid Elkjær
2013-01-01
I moderne kønsforskning er flere forskere begyndt at bruge neurovidenskabelige resultater til at belyse og forklare forskelle mellem kønnene. Et eksempel på denne tendens er professor Hans Bonde fra Københavns Universitet, der bl.a. er kendt for sin forskning inden for maskulinitet. I dette indlæg...
5. Kevadfestival kutsub metsa ja kontserdisaali / Iren Lill
Index Scriptorium Estoniae
Lill, Iren
2008-01-01
Üritustest 29. maist kuni 1. juunini toimuva Türi Kevadfestivali raames: koomilise laulumängu "Lopi ja Lapi" esietendus 31. mail Oisu rahvamajas (autoriteks kirjanik Leelo Tungal ja helilooja Tõnis Kaumann), Kadri-Ann Sumera kontsert pealkirjaga "Metsastseenid" 29. mail, Alo Põldmäe loodusfotode näituse "Muusikaline Neeruti" avamine, ansambli Svetilen kontsert 30. mail Türi kirikus, regilaulude laulmine Jaak Johansoni ja Riina Roose eestvedamisel ürituse "Ööülikool" raames 30. mail, festivali lõppkontsert Türi kirikus 1. juunil (esineb organist Ulla Krigul)
6. Seksist, linnast ja moest / Mervi Lill
Index Scriptorium Estoniae
Lill, Mervi
2008-01-01
USA 1998. aastal ekraanile jõudnud menusari "Seks ja linn" on mõjutanud sarja populaarsuse kasvuga kogu moetööstust ja muutunud globaalseks moekuulutajaks. Sarja stilist on Patricia Field, kes tegev ka 2008.a. kevadel esilinastuva mängufilmi "Sex and The City. The Movie" juures
7. Must lill heidab suure varju / Andres Laasik
Index Scriptorium Estoniae
Laasik, Andres, 1960-2016
2007-01-01
Brian De Palma krimimüsteerium "Must daalia" ("The Black Dahlia"), mis põhineb James Ellroy samanimelisel romaanil : operaator Vilmos Zsigmond : osades Josh Hartnett, Aaron Eckhart, Hilary Swank, Scarlett Johansson : Ameerika Ühendriigid 2006. Film noir'i stilistika kasutamisest filmis
8. Folginoppeid / Märt-Matis Lill
Index Scriptorium Estoniae
Lill, Märt-Matis, 1975-
2009-01-01
Muljeid Viljandi pärimusmuusikafestivalilt. Pikemalt soomlase J. Karjalaise, indiaanlase Lendava Kotka, rootsi löökpillimängija Petter Berndaleni, india interpreetide Shubhendra Rao ja Satyajit Talwalkari kontsertidest
9. Kevadfestival kutsub metsa ja kontserdisaali / Iren Lill
Index Scriptorium Estoniae
Lill, Iren
2008-01-01
Üritustest 29. maist kuni 1. juunini toimuva Türi Kevadfestivali raames: koomilise laulumängu "Lopi ja Lapi" esietendus 31. mail Oisu rahvamajas (autoriteks kirjanik Leelo Tungal ja helilooja Tõnis Kaumann), Kadri-Ann Sumera kontsert pealkirjaga "Metsastseenid" 29. mail, Alo Põldmäe loodusfotode näituse "Muusikaline Neeruti" avamine, ansambli Svetilen kontsert 30. mail Türi kirikus, regilaulude laulmine Jaak Johansoni ja Riina Roose eestvedamisel ürituse "Ööülikool" raames 30. mail, festivali lõppkontsert Türi kirikus 1. juunil (esineb organist Ulla Krigul)
10. Palacio de justicia de Lille – Francia
Directory of Open Access Journals (Sweden)
Willerval, J.
1969-06-01
Full Text Available The article provides a general description of this important building, and also a more detailed discussion of particular aspects of it. There is also a technical commentary of the structure, both in its general and particular nature, and the architectural as well as aesthetic aspects if it are considered. The whole design has formal and structural features that are unusual and noteworthy.Se describe el conjunto total y después se especifican las par tes del edificio del Palacio de Justicia, señalando las dependencias que contiene y la función de cada una. En una segunda parte del artículo se comenta técnicamente la estructura de la obra, también por partes y según su nivel, dando, a la vez, detalles arquitectónicos y estéticos. El conjunto edificado reúne características específicas formales y estructurales que lo destacan y hacen digno de especial atención y mención.
11. Jõustuvad muutused suurperede toetustes / Eli Lilles
Index Scriptorium Estoniae
Lilles, Eli
2007-01-01
1. juulist 2007 tõstetakse lapsetoetust alates pere kolmandast lapsest 900 kroonini. Peretoetustest, sünnitushüvitisest, vanemahüvitisest, riiklikest peretoetustest ja maksusoodustustest. Ilmunud ka Oma Saar 2. juuli 2007, lk. 1, pealkiri kujul: Lasterikaste perede toetus muutus ; Türi Rahvaleht 13. juuli 2007, lk. 4, pealkiri kujul: Suurperede toetused kasvavad
12. Jõustuvad muutused suurperede toetustes / Eli Lilles
Index Scriptorium Estoniae
Lilles, Eli
2007-01-01
1. juulist 2007 tõstetakse lapsetoetust alates pere kolmandast lapsest 900 kroonini. Peretoetustest, sünnitushüvitisest, vanemahüvitisest, riiklikest peretoetustest ja maksusoodustustest. Ilmunud ka Oma Saar 2. juuli 2007, lk. 1, pealkiri kujul: Lasterikaste perede toetus muutus ; Türi Rahvaleht 13. juuli 2007, lk. 4, pealkiri kujul: Suurperede toetused kasvavad
13. Piisavalt hullumeelne Andres Metspalu / Anne Lill
Index Scriptorium Estoniae
Lill, Anne, 1946-
2007-01-01
Vt. ka Linnaleht : Pärnu 7. sept., lk. 5-6, Linnaleht : Tartu 7. sept., lk. 8-9. Tartu Ülikooli biotehnoloogia professor Andres Metspalu on mitu aastat olnud Euroopa Inimesegeneetika Ühingu president ning Kanadas asuva rahvusvahelise biopankade konsortsiumi P3G juhatuse liige. Lisa: Kuumad geenid
14. The path to the nest of spiders The path to the nest of spiders
Directory of Open Access Journals (Sweden)
Eliane Luz Bayer
2008-04-01
Full Text Available Italo Calvino writes in his preface to The Path to the Nest of Spiders that the novel answers to the "ripeness of the time" since ht wrote it after wartime, a period when everyone had a tale to tell. He tells us that this is a story in which iobody is a hero and nobody has the class consciousness necessary to unify them in the struggle. Calvino acknowledges that it was difficult to conciliate his experiences with the postwar literary movement which he calls Neo-expresSionism, a term which, he thinks, describes better Italian Neo-realism. This is a book with a full realistic depictior of the incongruousness of the whole situation, showing rumen beings driven by loneliness, aggressiveness, unfulfilment and failure to meet, their nerves frayed by the War. It reveals human beings in their weaknesses, subjected to deterministic fates changing roles according to circumstance. Partisans shift to the Nazi side and inform on their f rmer allies and vice-versa, being later chased in revenge. The novel has as its setting Italy under Fascism and unde German occupation, the Italian people being divided betw en the fascists of the "Black Brigade" and the "Partisa4s" who belonged to the Resistance. Although this is a pOlitical book, it has universal appeal. At the same time that it livens up historical facts about the period, it moves our feelings. Calvino's book is about World War II as it is viewed and felt by a small outcast, Pin, who makes considerable efforts to be accepted and understood by adults. In his daily life Pinsuffers the consequences Of the war. His aggressive disposition reflects the environment which he has been brought up in: since he was born, his country has been at war. Besides that, his only sister is a whore, whom he hates and despises. Italo Calvino writes in his preface to The Path to the Nest of Spiders that the novel answers to the "ripeness of the time" since ht wrote it after wartime, a period when everyone had a tale to tell
15. A unique nest-protection strategy in a new species of spider wasp.
Directory of Open Access Journals (Sweden)
Michael Staab
Full Text Available Hymenoptera show a great variation in reproductive potential and nesting behavior, from thousands of eggs in sawflies to just a dozen in nest-provisioning wasps. Reduction in reproductive potential in evolutionary derived Hymenoptera is often facilitated by advanced behavioral mechanisms and nesting strategies. Here we describe a surprising nesting behavior that was previously unknown in the entire animal kingdom: the use of a vestibular cell filled with dead ants in a new spider wasp (Hymenoptera: Pompilidae species collected with trap nests in South-East China. We scientifically describe the 'Bone-house Wasp' as Deuteragenia ossarium sp. nov., named after graveyard bone-houses or ossuaries. We show that D. ossarium nests are less vulnerable to natural enemies than nests of other sympatric trap-nesting wasps, suggesting an effective nest protection strategy, most likely by utilizing chemical cues emanating from the dead ants.
16. Nesting Biology and Behavior of Euodynerus dantici (Rossi, 1790 (Hymenoptera: Vespidae: Eumeninae in Central Mongolia
Directory of Open Access Journals (Sweden)
2015-12-01
Full Text Available Nesting biology of Euodynerus dantici (Rossi, 1790 was studied in the Khugnu- Khaan Mountains of Khugnu-Tarna National Park, central Mongolia in 2014 using nest traps. Euodynerus dantici is univoltine in the study site, with one generation per growth season. Nest architecture and its structural parts were described in details. The inner cells of the nests were longer and contained a proportionately larger amount of food than the shorter outer cells. Females developed in inner cells and males developed in outer cells. Developmental stages of E. dantici is studied with details of pupation period. All basic behavioral elements of nesting females are described. A nest parasitoid, Chrysis ignita (Linnaeus, 1758 (Hymenoptera, Chrysididae was reared from E. dantici nests for the fi rst time. For provisioning, caterpillars of the family Noctuidae (Lepidoptera were hunted by females. Diversity in nest architecture is possibly a result of nest parasite pressure
17. Multilevel Analysis Methods for Partially Nested Cluster Randomized Trials
Science.gov (United States)
Sanders, Elizabeth A.
2011-01-01
This paper explores multilevel modeling approaches for 2-group randomized experiments in which a treatment condition involving clusters of individuals is compared to a control condition involving only ungrouped individuals, otherwise known as partially nested cluster randomized designs (PNCRTs). Strategies for comparing groups from a PNCRT in the…
18. Xylaria species associated with nests of Odontotermes formosanus in Taiwan.
Science.gov (United States)
Ju, Yu-Ming; Hsieh, Huei-Mei
2007-01-01
Nine species of Xylaria were collected in Taiwan from nests of Odontotermes formosanus, the only known macrotermitine termite in Taiwan. These include six newly described species, X. acuminatilongissima, X. atrodivaricata, X. brunneovinosa, X. griseosepiacea, X. intraflava and X. ochraceostroma, and three previously known species, X. cirrata, X. escharoidea and X. nigripes. We obtained cultures and ITS sequences from the nine species found in Taiwan and describe anamorphs for eight of them. Before the current study teleomorph-anamorph connections in the Xylaria species associated with termite nests have been established unequivocally in X. escharoidea only. Xylaria angulosa, X. fimbriata, X. kedahae, X. micrura, X. radicans, X. reinkingii and X. tolosa also are considered and annotated because they were reported to grow on ground and likely are associated with termite nests. Epitypifications are made for X. cirrata, X. escharoidea and X. nigripes. Xylaria sanchezii is considered a nomen dubium. Photographs are presented for most of the aforementioned species. A dichotomous key to 25 Xylaria species growing on termite nests or ground also is given.
19. Multi-Core Nested Depth-First Search
NARCIS (Netherlands)
Laarman, Alfons; Langerak, Rom; Pol, van de Jaco; Weber, Michael; Wijs, Anton; Bultan, T.; Hsiung, P.-A.
2011-01-01
The LTL Model Checking problem is reducible to finding accepting cycles in a graph. The Nested Depth-First Search (NDFS) algorithm detects accepting cycles efficiently: on-the-fly, with linear-time complexity and negligible memory overhead. The only downside of the algorithm is that it relies on an
20. Improved Multi-Core Nested Depth-First Search
NARCIS (Netherlands)
Evangelista, Sami; Laarman, Alfons; Petrucci, Laure; Pol, van de Jaco; Ramesh, S.
2012-01-01
This paper presents CNDFS, a tight integration of two earlier multi-core nested depth-first search (NDFS) algorithms for LTL model checking. CNDFS combines the different strengths and avoids some weaknesses of its predecessors. We compare CNDFS to an earlier ad-hoc combination of those two algorithm
1. Repeatability in nest construction by male three-spined sticklebacks
NARCIS (Netherlands)
Rushbrook, B. J.; Dingemanse, N. J.; Barber, I.
Structures built by animals may convey useful information about the builder that may be used by conspecifics in quality assessment. In fish, nest construction has been suggested to reflect qualities of individual builders, but little is known about how consistent individual differences are over
2. Sea turtle nesting distributions and oceanographic constraints on hatchling migration.
Science.gov (United States)
Putman, Nathan F; Bane, John M; Lohmann, Kenneth J
2010-12-07
Patterns of abundance across a species's reproductive range are influenced by ecological and environmental factors that affect the survival of offspring. For marine animals whose offspring must migrate long distances, natural selection may favour reproduction in areas near ocean currents that facilitate migratory movements. Similarly, selection may act against the use of potential reproductive areas from which offspring have difficulty emigrating. As a first step towards investigating this conceptual framework, we analysed loggerhead sea turtle (Caretta caretta) nest abundance along the southeastern US coast as a function of distance to the Gulf Stream System (GSS), the ocean current to which hatchlings in this region migrate. Results indicate that nest density increases as distance to the GSS decreases. Distance to the GSS can account for at least 90 per cent of spatial variation in regional nest density. Even at smaller spatial scales, where local beach conditions presumably exert strong effects, at least 38 per cent of the variance is explained by distance from the GSS. These findings suggest that proximity to favourable ocean currents strongly influences sea turtle nesting distributions. Similar factors may influence patterns of abundance across the reproductive ranges of diverse marine animals, such as penguins, eels, salmon and seals.
3. Nested structures approach for bulk 3D negative index materials
DEFF Research Database (Denmark)
Andryieuski, Andrei; Malureanu, Radu; Lavrinenko, Andrei
2009-01-01
We propose a generic conceptual idea to obtain bulk 3D negative index metamaterials, which exhibit isotropic properties. The design is based on the nested structures approach, when one element providing magnetic response is inserted into another design with negative dielectric constant. Both...
4. Using Gesture to Teach Seneca in a Language Nest School
Science.gov (United States)
Borgia, Melissa Elayne
2014-01-01
Seneca elder Sandy Dowdy and her granddaughter Autumn Crouse direct a language nest school for children aged two to five years in a small longhouse-shaped building, "Ganöhsesge:kha:' Hë:nödeyë:sta'":, or the Faithkeepers School, on the Seneca Allegany Territory in upstate New York. They practice immersion teaching and use forms of…
5. Behavior of greedy sparse representation algorithms on nested supports
DEFF Research Database (Denmark)
Mailhé, Boris; Sturm, Bob L.; Plumbley, Mark
2013-01-01
We study the links between recovery properties of Orthogonal Matching Pursuit (OMP) and the whole General MP class for sparse signals with nested supports, i.e., supports that share an inclusion relationship. In particular, we show that the support recovery optimality of those algorithms is not l...
6. Nested Genetic Algorithm for Resolving Overlapped Spectral Bands
Institute of Scientific and Technical Information of China (English)
2000-01-01
A nested genetic algorithm, including genetic parameter level and genetic implemented level for peak parameters, was proposed and applied for resolving overlapped spectral bands. By the genetic parameter level, parameters of genetic algorithm were optimized; moreover, the number of overlapped peaks was determined simultaneously. Then parameters of individual peaks were computed with the genetic implemented level.
7. NEST-SITE SELECTION IN THE CAPE SUGARBIRD We dedicate ...
African Journals Online (AJOL)
to fluctuations in wind-speed, an average value was determined for five .... where k is a constant (6,17 x 10-8) having units so that Hc is in cal em-I min-l (porter ...... predators constitute a major force limiting birds nesting on or near the ground.
8. Urine Nested Polymerase Chain Reaction in Neonatal Septicemia.
Science.gov (United States)
Das, B K; Suri, Shipra; Nath, Gopal; Prasad, Rajniti
2015-08-01
This cross-sectional study was done to evaluate diagnostic efficacy of urine nested polymerase chain reaction (PCR) using broad-range 16SrDNA PCR-based amplification, followed by restriction analysis and sequencing in neonatal septicemia. The study included 50 babies; 48% had vaginal delivery, 46% were preterm, 20% had a history of prolonged rupture of membranes and 56% were low birth weight (≤2500 g). Clinical presentations were lethargy (96%), respiratory distress (80%) and bleeding diathesis (16%). Absolute neutrophil count <1800/mm(3) was observed in 60%, and positive C-reactive protein in 46%. Thirty neonates had positive blood culture, and Klebsiella pneumoniae (22%) was the predominant organism. Nested urine PCR was positive in 38 (76%) and detected bacterial DNA in 8 neonates with negative blood cultures. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of nested PCR were 100, 60, 78.9, 100 and 84%, respectively, compared with blood culture. Nested PCR can detect most bacteria in single assay and identify unusual and unexpected causal agents.
9. Comparison of nest shapes and densities of two sympatric species ...
African Journals Online (AJOL)
Comparison of nest shapes and densities of two sympatric species of ... there are significant, though small, differences in height, diameter, number of caps, surface ... the addition of a first cap decreases the volume/surface ratio but a second or ...
10. Improved Multi-Core Nested Depth-First Search
NARCIS (Netherlands)
Evangelista, Sami; Laarman, Alfons; Petrucci, Laure; van de Pol, Jan Cornelis; Ramesh, S.
2012-01-01
This paper presents CNDFS, a tight integration of two earlier multi-core nested depth-first search (NDFS) algorithms for LTL model checking. CNDFS combines the different strengths and avoids some weaknesses of its predecessors. We compare CNDFS to an earlier ad-hoc combination of those two
11. Multi-Core Nested Depth-First Search
NARCIS (Netherlands)
Laarman, Alfons; Langerak, Romanus; van de Pol, Jan Cornelis; Weber, M.; Wijs, Anton; Bultan, T.; Hsiung, P.-A.
2011-01-01
The LTL Model Checking problem is reducible to finding accepting cycles in a graph. The Nested Depth-First Search (NDFS) algorithm detects accepting cycles efficiently: on-the-fly, with linear-time complexity and negligible memory overhead. The only downside of the algorithm is that it relies on an
12. The Empty Nest Syndrome: Ways to Enhance Quality of Life
Science.gov (United States)
Chen, Dianbing; Yang, Xinxiao; Aagard, Steve Dale
2012-01-01
Empty nest syndrome occurs as a result of urbanization and loosened relationships among family members. It may threaten the life quality of older adults and stability of society as a whole. This survey was designed to investigate the situation and factors that influence the life quality of a sample of older adults in a western state. Thirty-five…
13. Unit 9 Bird Nesting Survey : Biological Summary Report : May 2015
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This is the second year of the proposed 3 year survey project in Unit 9 of the Monte Vista NWR to look at breeding and nesting birds that use wet meadow/ wetland...
14. Efficient use of iterative solvers in nested topology optimization
DEFF Research Database (Denmark)
Amir, Oded; Stolpe, Mathias; Sigmund, Ole
2009-01-01
by a Krylov subspace iterative solver. By choosing convergence criteria for the iterative solver that are strongly related to the optimization objective and to the design sensitivities, it is possible to terminate the iterative solution of the nested equations earlier compared to traditional convergence...
15. Efficient Thread Labeling for Monitoring Programs with Nested Parallelism
Science.gov (United States)
Ha, Ok-Kyoon; Kim, Sun-Sook; Jun, Yong-Kee
It is difficult and cumbersome to detect data races occurred in an execution of parallel programs. Any on-the-fly race detection techniques using Lamport's happened-before relation needs a thread labeling scheme for generating unique identifiers which maintain logical concurrency information for the parallel threads. NR labeling is an efficient thread labeling scheme for the fork-join program model with nested parallelism, because its efficiency depends only on the nesting depth for every fork and join operation. This paper presents an improved NR labeling, called e-NR labeling, in which every thread generates its label by inheriting the pointer to its ancestor list from the parent threads or by updating the pointer in a constant amount of time and space. This labeling is more efficient than the NR labeling, because its efficiency does not depend on the nesting depth for every fork and join operation. Some experiments were performed with OpenMP programs having nesting depths of three or four and maximum parallelisms varying from 10,000 to 1,000,000. The results show that e-NR is 5 times faster than NR labeling and 4.3 times faster than OS labeling in the average time for creating and maintaining the thread labels. In average space required for labeling, it is 3.5 times smaller than NR labeling and 3 times smaller than OS labeling.
16. Nest success of snowy plovers (Charadrius nivosus) in the Southern high plains of Texas
Science.gov (United States)
Saalfeld, S.T.; Conway, Warren C.; Haukos, D.A.; Johnson, W.P.
2011-01-01
Snowy Plovers (Charadrius nivosus) nesting on edges of saline lakes within the Southern High Plains (SHP) of Texas are threatened by habitat degradation due to reduced artesian spring flow, making many saline lakes unsuitable for nesting and migrating shorebirds. Factors influencing nest success were evaluated, current nest success estimates in the SHP of Texas were compared to estimates obtained ten years prior, and causes and timing of nest failures determined. Overall, 215 nests were monitored from three saline lakes in 20082009, with nest success estimates from Program MARK ranging from 7-33% ( x??= 22%). The leading causes of nest failures were attributed to predation (40%) and weather (36%). Nest success was negatively influenced by number of plants within 707-cm 2 plot, positively influenced by percent surface water availability, and at one saline lake, negatively influenced by day during the nesting season (i.e., nest success declined later in the nesting season). When compared to estimates ten years prior (19981999), mean nest success has declined by 31%. If nesting Snowy Plovers continue to experience increased predation rates, decreased hydrological integrity, and habitat alterations, populations will continue to decline throughout this region.
17. Artificial Cavities and Nest Site Selection by Puerto Rican Parrots: a Multiscale Assessment
Directory of Open Access Journals (Sweden)
Thomas H. White, Jr.
2006-12-01
Full Text Available We examined nest site selection by Puerto Rican Parrots, a secondary cavity nester, at several spatial scales using the nest entrance as the central focal point relative to 20 habitat and spatial variables. The Puerto Rican Parrot is unique in that, since 2001, all known nesting in the wild has occurred in artificial cavities, which also provided us with an opportunity to evaluate nest site selection without confounding effects of the actual nest cavity characteristics. Because of the data limitations imposed by the small population size of this critically endangered endemic species, we employed a distribution-free statistical simulation approach to assess site selection relative to characteristics of used and unused nesting sites. Nest sites selected by Puerto Rican Parrots were characterized by greater horizontal and vertical visibility from the nest entrance, greater density of mature sierra palms, and a more westerly and leeward orientation of nest entrances than unused sites. Our results suggest that nest site selection in this species is an adaptive response to predation pressure, to which the parrots respond by selecting nest sites offering advantages in predator detection and avoidance at all stages of the nesting cycle. We conclude that identifying and replicating the “nest gestalt” of successful nesting sites may facilitate conservation efforts for this and other endangered avian species.
18. Nested-grid simulation of mercury over North America
Directory of Open Access Journals (Sweden)
Y. Zhang
2012-01-01
Full Text Available We have developed a new high-resolution (1/2° latitude by 2/3° longitude nested-grid mercury (Hg simulation over North America employing the GEOS-Chem global chemical transport model. Emissions, chemistry, deposition, and meteorology are self-consistent between the global and nested domains. Compared to the global model (4° latitude by 5° longitude, the nested model shows improved skill at capturing the high spatial and temporal variability of Hg wet deposition over North America observed by the Mercury Deposition Network (MDN in 2008–2009. The nested simulation resolves features such as land/ocean contrast and higher deposition due to orographic precipitation, and predicts more efficient convective rain scavenging of Hg over the southeast United States. However, the nested model overestimates Hg wet deposition over the Ohio River Valley region (ORV by 27%. We modify anthropogenic emission speciation profiles in the US EPA National Emission Inventory (NEI to account for the rapid in-plume reduction of reactive to elemental Hg (IPR simulation. This leads to a decrease in the model bias to +3% over the ORV region. Over the contiguous US, the correlation coefficient (r between MDN observations and our IPR simulation increases from 0.63 to 0.78. The IPR nested simulation generally reproduces the seasonal cycle in surface concentrations of speciated Hg from the Atmospheric Mercury Network (AMNet and Canadian Atmospheric Mercury Network (CAMNet. In the IPR simulation, annual mean reactive gaseous and particulate-bound Hg are within 80% and 10% of observations, respectively. In contrast, the simulation with unmodified anthropogenic Hg speciation profiles overestimates these observations by factors of 2 to 4. The nested model shows improved skill at capturing the horizontal variability of Hg observed over California during the ARCTAS aircraft campaign. We find that North American anthropogenic emissions account for 10–22% of Hg wet
19. Nest and brood attentiveness in female black ducks
Science.gov (United States)
Ringelman, J.K.; Longcore, J.R.; Owen, R.B.
1982-01-01
Incubation rhythms and brood attentiveness of radio-marked Black Ducks (Anas rubripes) were studied in southcentral Maine during 1977-1980. Recess duration and frequency differed between three females nesting near wetlands (x = 82 min, 2.3 recesses/day) and two nesting at upland sites(x = 183 min, I. I recesses/day), but incubation constancy was similar for all birds (x = 86.7%). A fourth wetland-nesting female apparently responded to the absence of down and concealing cover at the nest site by taking shorter and fewer recesses (x= 34 min, 1.0 recesses/day) than did other wetland-nesters with typical nests. Wetland-nesters took longer recesses with increasing air temperature and following long incubation sessions. After their ducklings were two weeks old, two brood-rearing females began leaving their broods to forage on nearby wetlands. Duration of rearing recess (x = 56 min) and total recess time (x = 94 min/day) were less during this mid-rearing stage than during the latter part of rearing (x = 265 min, 488 min/day). The two hen-brood bonds terminated at 43 and 48 days. We suggest that small endogenous nutrient reserves and the low density of invertebrate foods, typical of Black Duck breeding habitat, were critical factors affecting the evolution of Black Duck incubation behavior. Bouts of inattention during brood rearing may have also evolved in relation to food requirements; by foraging on wetlands away from their broods, females avoid competing with offspring for common food resources.
20. Interacting effects of aromatic plants and female age on nest-dwelling ectoparasites and blood-sucking flies in avian nests.
Science.gov (United States)
Tomás, G; Merino, S; Martínez-de la Puente, J; Moreno, J; Morales, J; Lobato, E; Rivero-de Aguilar, J; Del Cerro, S
2012-06-01
Some avian species incorporate aromatic plants to their nests. The "nest protection hypothesis", which posits that volatile secondary compounds contained in these plants may have antiparasite properties, has not received full support. All previous tests of this hypothesis have only considered effects on nest-dwelling ectoparasites, but not on blood-sucking flies. The "drug hypothesis" posits that aromatic plants may stimulate nestling immune system, development, or condition. We tested these hypotheses experimentally in wild blue tits, Cyanistes caeruleus, a species that adds aromatic plants to their nests. We supplemented aromatic plants to half of a sample of nests, while adding grass to the other half of nests. We quantified abundance of two groups of blood-sucking flies (blackflies and biting midges) at two different stages of the reproductive period, and abundance of three nest-dwelling ectoparasites (fleas, mites, and blowflies). Experimental supplementation of aromatic plants reduced abundance of fleas only in nests of yearling females and not in nests of older females. Blackflies and biting midges were both more numerous in nests of yearling females than in nests of older females. Mass of aromatic plants added by females was negatively related with abundance of fleas in control nests but not in experimental nests supplied with aromatic plants. Mass of plants added by females was also positively related with abundance of blackflies during the nestling stage. Finally, aromatic plants did not affect nestling growth or immune responses. We conclude that several factors such as female experience and their ability to add plants to the nest interact to explain effects of aromatic plants on different parasites.
1. Sunrise nest attendance and aggression by least Bell's vireos fail to deter cowbird parasitism
Science.gov (United States)
Sharp, Bryan L.; Kus, Barbara E.
2004-01-01
We video-recorded three, natural, brood-parasitism events by Brown-headed Cowbirds (Molothrus ater) at nests of Least Bell's Vireos (Vireo bellii pusillus). All instances occurred near dawn, during both egg-laying and incubation stages of the nesting cycle. In each case, an adult vireo was on the nest when the female cowbird arrived. Both members of each parasitized pair vigorously attacked the intruding cowbird, but in no encounter did a pair of vireos successfully defend its nest from parasitism. Thus, Least Bell's Vireos in our study were unable to prevent a female cowbird from parasitizing their nests once the cowbird had reached the nest.
2. Determinants of abundance and effects of blood-sucking flying insects in the nest of a hole-nesting bird
NARCIS (Netherlands)
Tomás, G.; Merino, S.; Martínez-de la Puente, J.; Moreno, J.; Morales, J.; Lobato, E.
2008-01-01
Compared to non-flying nest-dwelling ectoparasites, the biology of most species of flying ectoparasites and its potential impact on avian hosts is poorly known and rarely, if ever, reported. In this study we explore for the first time the factors that may affect biting midge (Diptera:
3. Optimal reservoir operation policies using novel nested algorithms
Science.gov (United States)
Delipetrev, Blagoj; Jonoski, Andreja; Solomatine, Dimitri
2015-04-01
Historically, the two most widely practiced methods for optimal reservoir operation have been dynamic programming (DP) and stochastic dynamic programming (SDP). These two methods suffer from the so called "dual curse" which prevents them to be used in reasonably complex water systems. The first one is the "curse of dimensionality" that denotes an exponential growth of the computational complexity with the state - decision space dimension. The second one is the "curse of modelling" that requires an explicit model of each component of the water system to anticipate the effect of each system's transition. We address the problem of optimal reservoir operation concerning multiple objectives that are related to 1) reservoir releases to satisfy several downstream users competing for water with dynamically varying demands, 2) deviations from the target minimum and maximum reservoir water levels and 3) hydropower production that is a combination of the reservoir water level and the reservoir releases. Addressing such a problem with classical methods (DP and SDP) requires a reasonably high level of discretization of the reservoir storage volume, which in combination with the required releases discretization for meeting the demands of downstream users leads to computationally expensive formulations and causes the curse of dimensionality. We present a novel approach, named "nested" that is implemented in DP, SDP and reinforcement learning (RL) and correspondingly three new algorithms are developed named nested DP (nDP), nested SDP (nSDP) and nested RL (nRL). The nested algorithms are composed from two algorithms: 1) DP, SDP or RL and 2) nested optimization algorithm. Depending on the way we formulate the objective function related to deficits in the allocation problem in the nested optimization, two methods are implemented: 1) Simplex for linear allocation problems, and 2) quadratic Knapsack method in the case of nonlinear problems. The novel idea is to include the nested
4. Nesting biology of Centris (Hemisiella tarsata Smith (Hymenoptera, Apidae, Centridini
Directory of Open Access Journals (Sweden)
Cândida M. L. Aguiar
2004-09-01
Full Text Available Nests of Centris tarsata Smith, 1874 were obtained from trap-nests in areas of dry semi-deciduous forest (Baixa Grande and caatinga (Ipirá, in the State of Bahia. Nesting occurred in bamboo canes and in tubes of black cardboard with 5.8 cm (= small tube and 10.5 cm (= large tube in length and 0.6 and 0.8 cm in diameter, respectively. In both areas C. tarsata nested during the wet season producing four generations in Baixa Grande and three generations in Ipirá. The immatures of one generation underwent diapause at both sites. The bees constructed their nests with a mixture of sand and oil. In general, the cells were elongated and arranged in linear series with its opening pointing towards the nest entrance. Completed nests had two to three cells in small tubes, one to seven cells in large tubes, and two to 13 cells in bamboo canes. The nest plug resembled an uncompleted cell and was externally covered with oil. The cells were provisioned with pollen, oil, and nectar. Nests were parasitized by Mesocheira bicolor (Fabricius, 1804 (Hymenoptera: Apidae and other not identify bee species.Ninhos de Centris tarsata Smith, 1874 foram obtidos através da utilização de ninhos-armadilha, em áreas de floresta estacional semi-decídua (Baixa Grande e de caatinga (Ipirá, no Estado da Bahia. A nidificação ocorreu em gomos de bambus e em tubos de cartolina preta, estes com comprimentos de 5,8 cm (= tubos pequenos e 10,5 cm (= tubos grandes, e diâmetro de 0,6 e 0,8 cm, respectivamente. Em ambas as áreas C. tarsata nidificou durante a estação úmida, produzindo quatro gerações anuais em Baixa Grande e três em Ipirá. Os imaturos de uma das gerações passaram por diapausa em ambos os locais. As abelhas construíram seus ninhos com uma mistura de areia e óleo. Em geral, as células foram alongadas e arranjadas em série linear, com sua abertura dirigida para a entrada do ninho. Os ninhos completados tinham de duas a três células nos tubos pequenos
5. Potential influences of climate and nest structure on spotted owl reproductive success: a biophysical approach.
Science.gov (United States)
Rockweit, Jeremy T; Franklin, Alan B; Bakken, George S; Gutiérrez, R J
2012-01-01
Many bird species do not make their own nests; therefore, selection of existing sites that provide adequate microclimates is critical. This is particularly true for owls in north temperate climates that often nest early in the year when inclement weather is common. Spotted owls use three main types of nest structures, each of which are structurally distinct and may provide varying levels of protection to the eggs or young. We tested the hypothesis that spotted owl nest configuration influences nest microclimate using both experimental and observational data. We used a wind tunnel to estimate the convective heat transfer coefficient (h(c)) of eggs in 25 potential nest configurations that mimicked 2 nest types (top-cavity and platform nests), at 3 different wind speeds. We then used the estimates of h(c) in a biophysical heat transfer model to estimate how long it would take unattended eggs to cool from incubation temperature (~36 °C) to physiological zero temperature (PZT; ~26 °C) under natural environmental conditions. Our results indicated that the structural configuration of nests influences the cooling time of the eggs inside those nests, and hence, influences the nest microclimate. Estimates of time to PZT ranged from 10.6 minutes to 33.3 minutes. Nest configurations that were most similar to platform nests always had the fastest egg cooling times, suggesting that platform nests were the least protective of those nests we tested. Our field data coupled with our experimental results suggested that nest choice is important for the reproductive success of owls during years of inclement weather or in regions characterized by inclement weather during the nesting season.
6. Potential influences of climate and nest structure on spotted owl reproductive success: a biophysical approach.
Directory of Open Access Journals (Sweden)
Jeremy T Rockweit
Full Text Available Many bird species do not make their own nests; therefore, selection of existing sites that provide adequate microclimates is critical. This is particularly true for owls in north temperate climates that often nest early in the year when inclement weather is common. Spotted owls use three main types of nest structures, each of which are structurally distinct and may provide varying levels of protection to the eggs or young. We tested the hypothesis that spotted owl nest configuration influences nest microclimate using both experimental and observational data. We used a wind tunnel to estimate the convective heat transfer coefficient (h(c of eggs in 25 potential nest configurations that mimicked 2 nest types (top-cavity and platform nests, at 3 different wind speeds. We then used the estimates of h(c in a biophysical heat transfer model to estimate how long it would take unattended eggs to cool from incubation temperature (~36 °C to physiological zero temperature (PZT; ~26 °C under natural environmental conditions. Our results indicated that the structural configuration of nests influences the cooling time of the eggs inside those nests, and hence, influences the nest microclimate. Estimates of time to PZT ranged from 10.6 minutes to 33.3 minutes. Nest configurations that were most similar to platform nests always had the fastest egg cooling times, suggesting that platform nests were the least protective of those nests we tested. Our field data coupled with our experimental results suggested that nest choice is important for the reproductive success of owls during years of inclement weather or in regions characterized by inclement weather during the nesting season.
7. Neighbourhood society: nesting dynamics, usurpations and social behaviour in solitary bees.
Directory of Open Access Journals (Sweden)
Kateřina Černá
Full Text Available Intraspecific cleptoparasitism represents a facultative strategy advantageous for reducing time and energy costs. However, only a few studies about nesting dynamics have described intraspecific cleptoparasitic behaviour in obligate solitary bees. We focused on nesting dynamics with the characterisation of nest owner replacements and frequency of true usurpation in four aggregating species belonging to different phylogenetic lineages--Andrena vaga (Andrenidae, Anthophora plumipes (Apidae, Colletes cunicularius (Colletidae, and Osmia rufa (Megachilidae. Our study, based on the regular observation of individually marked females, shows that nest owner replacement affects 10-45% of nests across all of the studied species and years. However, 39-90% of these nests had been abandoned before owner change and thus true nest usurpations represent only a part of observed nest replacement cases. Females tend to abandon their nests regularly and found new ones when they live long enough, which is in accordance with risk-spreading strategy. We suggest that the original facultative strategy of observed solitary bees during nest founding is not cleptoparasitism per se but rather reuse of any pre-existing nest (similar to "entering" strategy in apoid wasps. This is supported by gradual increase of nests founded by "entering" during the season with an increase in the number of available nests. Although the frequent reuse of conspecific nests results in frequent contact between solitary females, and rarely, in the short-term coexistence of two females in one nest, we detected unexpectedly low level of conflict in these neighbourhood societies. We suggest that nesting dynamics with regular nest switching and reusing reduces long-term and costly intraspecific aggression, a key factor for the origin and evolution of sociality.
8. Arctic foxes, lemmings, and canada goose nest survival at cape Churchill, Manitoba
Science.gov (United States)
Reiter, M.E.; Andersen, D.E.
2011-01-01
We examined factors influencing Canada Goose (Branta canadensis interior) annual nest success, including the relative abundance of collared lemmings (Dicrostonyx richardsoni), arctic fox (Alopex lagopus) den occupancy, nest density, and spring phenology using data collected during annual Canada Goose breeding area surveys at Cape Churchill, Manitoba. Nest density and arctic fox den occupancy strongly influenced Canada Goose nest success. High nest density resulted in higher nest success and high den occupancy reduced nest success. Nest success was not influenced by lemming abundance in the current or previous year as predicted by the "bird-lemming" hypothesis. Reducing arctic fox abundance through targeted management increased nest survival of Canada Geese; a result that further emphasizes the importance of arctic fox as nest predators in this system. The spatial distribution of nest predators, at least for dispersed-nesting geese, may be most important for nest survival, regardless of the abundance of small mammals in the local ecosystem. Further understanding of the factors influencing the magnitude and variance in arctic fox abundance in this region, and the spatial scale at which these factors are realized, is necessary to fully explain predator-prey-alternative prey dynamics in this system. ?? 2011 by the Wilson Ornithological Society.
9. Common blackbirdsTurdus merula use anthropogenic structures as nesting sites in an urbanized landscape
Institute of Scientific and Technical Information of China (English)
Yanping WANG; Qin HUANG; Sisi LAN; Qin ZHANG; Shuihua CHEN
2015-01-01
The common blackbirdTurdus merula is one of the most highly urbanized bird species. However, to date, the use of anthropogenic structures as nesting sites in the common blackbird is rarely documented, and the factors influencing its use of the anthropogenic structures as nesting sites remain unclear. In this study, we systematically quantified and determined the factors in-fluencing the use of anthropogenic structures as nesting sites in common blackbirds in a highly urbanized city of Hangzhou, Chi-na. We searched for nests of common blackbirds during four breeding seasons from 2010 to 2013. Among the 60 nests found, 34 nests were in anthropogenic structures such as wall ledges, air condition mounts, window canopies, cable poles, guardrails, eaves, balcony frames, flowerpots and flower shelves on balconies. We found that the available anthropogenic nest sites and the availa-ble nesting trees were main factors determining the use of anthropogenic structures as nesting sites in common blackbirds. In ur-ban environments, the amount of available anthropogenic nesting sites increased significantly, whereas the number of natural nesting sites reduced greatly. Our results suggest that common blackbirds can adjust their nest sites in response to urbanization and such nesting behavior shifts may aid them to colonize urban environments. From a management viewpoint, our results indi-cate that behavioral flexibility should be taken into account for effective urban wildlife management and conservation [Current Zoology 61 (3): 435–443, 2015].
10. Does nest luminosity play a role in recognition of parasitic eggs in domed nests? A case study of the red bishop
Science.gov (United States)
Honza, Marcel; Šulc, Michal; Cherry, Michael I.
2014-12-01
Certain light environments may hinder egg discrimination by hosts of foreign eggs, which could in some circumstances lead to the acceptance of non-mimetic eggs by hosts. We measured light parameters at red bishop ( Euplectes orix) nests and used a model of avian visual processing to quantify the detectability of eggs in the light environment in which they are perceived. We found that the overall amount of light was very variable between red bishop nests and always sufficient for colour discrimination. A model of avian visual processing revealed that nest luminosity had no influence on host responses towards eggs which were painted dark brown. Dark eggs do not appear to be cryptic in red bishop nests and can be distinguished with ease, whereas natural red bishop eggs are usually accepted, despite the domed structure of the nest. We found little variation in both chromatic and achromatic contrasts between host and artificial eggs, indicating that there was very little variation in the light quality inside nests. We suggest that nest luminosity is likely to play a role in egg recognition in situations when light reaches threshold values for colour discrimination, i.e. in scotopic as opposed to photopic vision. Rejection rates for dark eggs were higher than for bright (conspecific) foreign eggs. More investigation of domed nest-building species is required, as this type of nest appears to have a highly variable light environment, dependent on both nest structure and habitat.
11. Monitoring of Nesting Spectacled Eiders on Kigigak Island, Yukon Delta NWR, 2011
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Nesting spectacled eiders were monitored for the 20th consecutive year on Kigigak Island, Alaska in 2011. Clutch size, hatch date, and final nest status were...
12. Report of Black Duck Nesting on the Blackwater River Migratory Bird Refuge 1932
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — The purpose of this investigation is to determine the extent of nesting in the area by ducks and the amount of destruction during the nesting season by predacious...
13. Fighting fish (Betta splendens) bubble nests do not inhibit microbial growth.
Science.gov (United States)
Brown, Alexandria C; Clotfelter, Ethan D
2012-12-01
Some organisms produce antimicrobial substances in nesting foam to favorably manipulate the environment to which their developing offspring are exposed. We tested if fighting fish Betta splendens foamy nest material, which is comprised of bubbles produced in the oral cavity of nesting males, has antimicrobial properties against a pathogenic bacteria (Edwardsiella tarda), a nonpathogenic bacteria (Escherichia coli), or a pathogenic oomycete (Saprolegnia parasitica). We also tested if exposure to nest material increases larval survival by performing in vitro fertilizations and individually incubating eggs in bubble nest extract or tank water (control). Our results show no evidence of antimicrobial properties of bubble nests. On the contrary, bubble nests provided favorable microenvironments for the growth of Saprolegnia parasitica. Our results confirm earlier work citing the importance of male nest attendance, and suggest that the mechanism responsible for decreased survival in the absence of attending males is pathogenic microbes.
14. A survey of potential raptor nesting sites in the southern Askinuk Mountains, Alaska
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — During June 1989, selected areas of the southern Askinuk Mountains were surveyed for raptor nests. Ten nests were located on rock outcroppings at seven locations....
15. Evaluation of the 100 meter protective zone for bald eagle nests in southeast Alaska
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Bald eagle (Haliaeetus leucocephalus) nests in southeast Alaska have been protected by a 100 m buffer zone since 1968. Nests near logging developments were surveyed...
16. Nested by design: model fitting and interpretation in a mixed model era
National Research Council Canada - National Science Library
Schielzeth, Holger; Nakagawa, Shinichi; Freckleton, Robert
2013-01-01
...‐effects models offer a powerful framework to do so. Nested effects can usually be fitted using the syntax for crossed effects in mixed models, provided that the coding reflects implicit nesting...
17. Nesting survey for Aleutian Canada geese at Nizki-Alaid, Alaska in 1990
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Nesting success was high in 1990, and moderate numbers of subadult birds, which may nest in future years, were present. Furthermore, a translocation of 38 geese...
18. Leucophora Satellite Flies (Diptera: Anthomyiidae) as Nest Parasites of Sweat Bees (Hymenoptera: Halictidae) in the Neotropics
National Research Council Canada - National Science Library
Polidori, C; Michelsen, V; Nieves-Aldrey, J L
2015-01-01
.... Females of both species perch on small stones or sticks within a dense nest aggregation of the bees and then track pollen-loaded bees in flight with great precision, eventually following them into their nests...
19. Survey of Nesting Osprey at Back Bay National Wildlife Refuge and False Cape State Park
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — A survey of nesting Osprey (Pandion Haliaetus) was conducted during the nesting season of 1990. The survey was conducted in the bay waters of Back Bay National...
20. A survey for cliff-nesting birds of prey along the Noatak River, Alaska
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — The primary objective of the study was to locate peregrine falcon nesting sites and to locate nest sites of other raptor species and assess their location in...
1. Survey of Nesting Osprey at Back Bay National Wildlife Refuge and False Cape State Park
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — A survey of nesting Osprey (Pandion Haliaetus) was conducted during the nesting season of 1989. The survey was conducted in the bay waters of Back Bay National...
2. Spectacled eider (Somateria fischeri) nest records Kashunuk River and Kigigak Island, Alaska, 1991-2004
Data.gov (United States)
U.S. Geological Survey, Department of the Interior — Data set containing nest records for Spectacled Eiders near the Kashunuk River and on Kigigak Island, within the Yukon-Kuskokwim Delta, Alaska. Nests were visited...
3. Food use and nutrition of black ducks nesting in Maine
Science.gov (United States)
Reinecke, K.J.; Owen, R.B.
1980-01-01
Based on 32 adult black ducks (Anas rubripes) collected during the nesting seasons of 1974-76, the proportion of macro invertebrates (as aggregate [average] percent of dry weight) in the diet of males, egg-laying females, and postlaying females was 60, 75, and 55%, respectivey. Sample sizes were small, and the differences associated with sex and reproductive condition were not signficant. Molluscs, Isopods, ephemeropteran and odonate nymphs, and coleopteran, trichopteran, and dipteran larvae contributed 74% of the dry weight and 64% of the gross energy ingested. Data from proximate analyses of 9 invertebrate and 9 plant foods were combined with food habits data to estimate the nutrients available to breeding hens. We concluded that females with access to an adequate amount of natural food including invertebrates and the seeds and tubers of aquatic plants would obtain sufficient minerals, protein, and energy for reproduction. Food quality does not appear to limit the density of black ducks nesting in Maine.
4. Clustered nested sampling: efficient Bayesian inference for cosmology
CERN Document Server
Shaw, R; Hobson, M P
2007-01-01
Bayesian model selection provides the cosmologist with an exacting tool to distinguish between competing models based purely on the data, via the Bayesian evidence. Previous methods to calculate this quantity either lacked general applicability or were computationally demanding. However, nested sampling (Skilling 2004), which was recently applied successfully to cosmology by Muhkerjee et al. 2006, overcomes both of these impediments. Their implementation restricts the parameter space sampled, and thus improves the efficiency, using a decreasing ellipsoidal bound in the $n$-dimensional parameter space centred on the maximum likelihood point. However, if the likelihood function contains any multi-modality, then the ellipse is prevented from constraining the sampling region efficiently. In this paper we introduce a method of clustered ellipsoidal nested sampling which can form multiple ellipses around each individual peak in the likelihood. In addition we have implemented a method for determining the expectation...
5. Experimental demonstration of an inertial collimation mechanism in nested outflows
CERN Document Server
Yurchak, R; Pelka, A; Pikuz, S; Falize, E; Vinci, T; Koenig, M; Loupias, B; Benuzzi-Mounaix, A; Fatenejad, M; Tzeferacos, P; Lamb, D Q; Blackman, E G
2014-01-01
Interaction between a central outflow and a surrounding wind is common in astrophysical sources powered by accretion. Understanding how the interaction might help to collimate the inner central outflow is of interest for assessing astrophysical jet formation paradigms. In this context, we studied the interaction between two nested supersonic plasma flows generated by focusing a long pulse high-energy laser beam onto a solid target. A nested geometry was created by shaping the energy distribution at the focal spot with a dedicated phase plate. Optical and X-ray diagnostics were used to study the interacting flows. Experimental results and numerical hydrodynamic simulations indeed show the formation of strongly collimated jets. Our work experimentally confirms the "shock-focused inertial confinement" mechanism proposed in previous theoretical astrophysics investigations.
6. NANOFIBROUS MATS WITH BIRD'S NEST PATTERNS BY ELECTROSPINNING
Institute of Scientific and Technical Information of China (English)
Xiang-yu Ye; Xiao-jun Huang; Zhi-kang Xu
2012-01-01
Electrospun material with bio-inspired ordered architectures and patterns is very interesting,yet remains a challenge.We report here that nanofibrous mats with bird's nest patterned structures can be directly electrospun from chlorinated polypropylene solutions doped with an ionic liquid.The solution viscosity and the ionic liquid content are two dominant factors to influence the lopological morphology of the nanofibrous mats.The patterned structures can be further modulated by the collection time of electrospinning,the humidity of environment and the design of collector.We suggest the electrostatic repulsion between the residual charges of the mat surface and the upcoming nanofibers plays a key role in the formation of the bird's nest patterns.
7. Optimization and Evaluation of Nested Queries and Procedures
CERN Document Server
Guravannavar, Ravindra
2009-01-01
Many database applications perform complex data retrieval and update tasks. Nested queries, and queries that invoke user-defined functions, which are written using a mix of procedural and SQL constructs, are often used in such applications. A straight-forward evaluation of such queries involves repeated execution of parameterized sub-queries or blocks containing queries and procedural code. An important problem that arises while optimizing nested queries as well as queries with joins, aggregates and set operations is the problem of finding an optimal sort order from a factorial number of possible sort orders. We show that even a special case of this problem is NP-Hard, and present practical heuristics that are effective and easy to incorporate in existing query optimizers. We also consider iterative execution of queries and updates inside complex procedural blocks such as user-defined functions and stored procedures. Parameter batching is an important means of improving performance as it enables set-orientate...
8. Towards a streaming model for nested data parallelism
DEFF Research Database (Denmark)
2013-01-01
-flattening execution strategy, comes at the price of potentially prohibitive space usage in the common case of computations with an excess of available parallelism, such as dense-matrix multiplication. We present a simple nested data-parallel functional language and associated cost semantics that retains NESL......'s intuitive work--depth model for time complexity, but also allows highly parallel computations to be expressed in a space-efficient way, in the sense that memory usage on a single (or a few) processors is of the same order as for a sequential formulation of the algorithm, and in general scales smoothly......-processable in a streaming fashion. This semantics is directly compatible with previously proposed piecewise execution models for nested data parallelism, but allows the expected space usage to be reasoned about directly at the source-language level. The language definition and implementation are still very much work...
9. Using Technology-Nested Instructional Strategies to Enhance Student Learning
Directory of Open Access Journals (Sweden)
Angela Lumpkin, PhD
2015-08-01
Full Text Available Students today expect the use of technology in their classes, rather than have to listen to less-than-engaging lectures. College students are connected electronically and incessant technology consumers. As a result, they may prefer the infusion of technologies to help them learn and enjoy the process of learning, rather than having to listen exclusively to lectures. To investigate this, the authors solicited student perceptions to assess the importance of learning through technology-nested instructional strategies. Student perceptions give direction to and affirm the benefits of instructional strategies that increase student motivation to engage more actively in their learning. Based on quantitative and qualitative responses through action research in multiple courses, students perceive their learning as more engaging and enjoyable when technology-nested instructional strategies are infused into their classes.
10. The mathematics of non-linear metrics for nested networks
Science.gov (United States)
Wu, Rui-Jie; Shi, Gui-Yuan; Zhang, Yi-Cheng; Mariani, Manuel Sebastian
2016-10-01
Numerical analysis of data from international trade and ecological networks has shown that the non-linear fitness-complexity metric is the best candidate to rank nodes by importance in bipartite networks that exhibit a nested structure. Despite its relevance for real networks, the mathematical properties of the metric and its variants remain largely unexplored. Here, we perform an analytic and numeric study of the fitness-complexity metric and a new variant, called minimal extremal metric. We rigorously derive exact expressions for node scores for perfectly nested networks and show that these expressions explain the non-trivial convergence properties of the metrics. A comparison between the fitness-complexity metric and the minimal extremal metric on real data reveals that the latter can produce improved rankings if the input data are reliable.
11. Extraction of Flat and Nested Data Records from Web Pages
CERN Document Server
Hiremath, P S
2010-01-01
This paper studies the problem of identification and extraction of flat and nested data records from a given web page. With the explosive growth of information sources available on the World Wide Web, it has become increasingly difficult to identify the relevant pieces of information, since web pages are often cluttered with irrelevant content like advertisements, navigation-panels, copyright notices etc., surrounding the main content of the web page. Hence, it is useful to mine such data regions and data records in order to extract information from such web pages to provide value-added services. Currently available automatic techniques to mine data regions and data records from web pages are still unsatisfactory because of their poor performance. In this paper a novel method to identify and extract the flat and nested data records from the web pages automatically is proposed. It comprises of two steps : (1) Identification and Extraction of the data regions based on visual clues information. (2) Identificatio...
12. Temperature variation in nests of Caiman crocodilus (Crocodylia: Alligatoridae
Directory of Open Access Journals (Sweden)
Armando H. Escobedo Galván
2006-11-01
Full Text Available Caiman crocodilus is a widely distributed species in the Neotropics; however, studies of incubation temperatures in wildlife are uncommon. Incubation temperature in four nests of Caiman crocodilus were measured with a digital thermometer, in the National Wildlife Refuge Caño Negro, Costa Rica. Average temperatures in these four nests (no. 1-4 were 32.13 + 0.92 °C (no. 1, 32.46 + 0.77 °C (no. 2, 33.60 + 0.95 °C (no. 3, and 31.78 + 2.30 °C (no. 4. Temperature variations recorded showed higher temperatures than those reported from other studies in Caño Negro. The temperatures registered in this study will lead to a higher proportion of males within the caiman population, reducing the number of future reproducing females and, therefore, in the population viability.
13. PolyChord: next-generation nested sampling
CERN Document Server
Handley, W J; Lasenby, A N
2015-01-01
PolyChord is a novel nested sampling algorithm tailored for high-dimensional parameter spaces. This paper coincides with the release of PolyChord v1.3, and provides an extensive account of the algorithm. PolyChord utilises slice sampling at each iteration to sample within the hard likelihood constraint of nested sampling. It can identify and evolve separate modes of a posterior semi-independently, and is parallelised using openMPI. It is capable of exploiting a hierarchy of parameter speeds such as those present in CosmoMC and CAMB, and is now in use in the CosmoChord and ModeChord codes. PolyChord is available for download at: http://ccpforge.cse.rl.ac.uk/gf/project/polychord/
14. DNest4: Diffusive Nested Sampling in C++ and Python
CERN Document Server
Brewer, Brendon J
2016-01-01
In probabilistic (Bayesian) inferences, we typically want to compute properties of the posterior distribution, describing knowledge of unknown quantities in the context of a particular dataset and the assumed prior information. The marginal likelihood, also known as the "evidence", is a key quantity in Bayesian model selection. The Diffusive Nested Sampling algorithm, a variant of Nested Sampling, is a powerful tool for generating posterior samples and estimating marginal likelihoods. It is effective at solving complex problems including many where the posterior distribution is multimodal or has strong dependencies between variables. DNest4 is an open source (MIT licensed), multi-threaded implementation of this algorithm in C++11, along with associated utilities including: i) RJObject, a class template for finite mixture models, (ii) A Python package allowing basic use without C++ coding, and iii) Experimental support for models implemented in Julia. In this paper we demonstrate DNest4 usage through examples ...
15. Can hedgerow management mitigate the impacts of predation on songbird nest survival?
Science.gov (United States)
Dunn, Jenny C; Gruar, Derek; Stoate, Chris; Szczur, John; Peach, Will J
2016-12-15
Nest predators can have significant impacts on songbird reproductive success. These impacts may be amplified by habitat simplification and here we test whether sympathetic management of farmland hedgerows can reduce nest depredation, especially by corvids. We test whether songbirds select nest sites according to structural features of hedgerows (including nest visibility and accessibility), and whether these features influence nest predation risk. Songbirds selected nesting sites affording higher vegetation cover above the nest, increased visibility on the nest-side of the hedgerow and reduced visibility on the far side of the hedge. Nest survival was unrelated to corvid abundance and only weakly related (at the egg stage) to corvid nest proximity. Nest survival at the chick stage was higher where vegetation structure restricted access to corvid-sized predators (averaging 0.78 vs. 0.53), and at nests close to potential vantage points. Overall nest survival was sensitive to hedgerow structure (accessibility) particularly at low exposure to corvid predation, while the overall impact of corvid exposure was dependent on the relationship involving proximity to vantage points. Nest survival over the chick stage was much higher (0.67) in stock-proof, trimmed and mechanically cut hedgerows, (which tended to provide lower side visibility and accessibility) than in recently laid, remnant or leggy hedgerows (0.18). Long-term reductions in the management of British hedgerows may therefore be exposing nesting songbirds to increased predation risk. We recommend regular rotational cutting of hedgerows to maintain a dense woody structure and thereby reduce songbird nest predation. Copyright © 2016 Elsevier Ltd. All rights reserved.
16. Uncertain nest fates in songbird studies and variation in Mayfield estimation
Science.gov (United States)
Manolis, J.C.; Andersen, D.E.; Cuthbert, F.J.
2000-01-01
Determining whether nesting attempts are successful can be difficult. Yet, current protocols for estimating nesting success do not address how uncertain nest fates should be handled. We examined the problem of nest-fate uncertainty as it relates to Mayfield estimation of nesting success and in analyses of factors that influence success. We used data from Minnesota to illustrate the potential effect of uncertain fate; 40% of Ovenbird (Seiurus aurocapillus; n = 127) nests and 30% of Least Flycatcher (Empidonax minimus; n = 144) nests had uncertain fates. How this uncertainty is incorporated into Mayfield estimates of success varied widely among researchers. In a survey of researchers who use the Mayfield method, 9 of 22 respondents (of 40 contacted) excluded nests with uncertain fate. Excluding uncertain fates is counter to how Mayfield first described his estimator and can result in severe downward bias. The remaining respondents (59%) included nests with uncertain fate but varied in how they terminated the exposure period. We developed a simulation model that calculated Mayfield estimates using different approaches and compared them with a known rate of nesting success. Magnitude of bias in Mayfield estimates varied considerably in our simulations. The approach with the least bias terminated exposure with the last observed active date for nests with uncertain fate, and with the midpoint between last observed active and first observed inactive dates for nests with known fate. In addition, information necessary to interpret and compare Mayfield estimates often is not reported. These values, including variance estimates and the period lengths used to estimate survival rates, should be reported with Mayfield estimates. Finally, nest fate is commonly used as a categorical variable in studies of factors affecting nesting success. In this approach, however, nests with uncertain fate must be excluded. An alternative approach is Cox regression, which incorporates nests with
17. Bird predation on nest of a social wasp in Brazilian cerrado
OpenAIRE
Barros Henriques, Raimundo Paulo; Torre Palma, Alexandre Ramlo
2015-01-01
Birds are rarely observed preying upon wasps' nests (Bertoni 1911, Rau 1941, AIvarez del Toro 1950, Skutch 1959, Windsor 1976). Many of the observations are recorded in tropical forest on nests of Polybia and Metapolybia. In this note we present the first observations on the predation by the curIcrestedjay (Cyanocorax cristatellus) upon the nest of a social wasp (Apoica pallens) in cerrados of Central Brazil. Birds are rarely observed preying upon wasps' nests (Bertoni 1911, Rau 1941, AIva...
18. A red-cockaded woodpecker group with two simultaneous nest trees
Science.gov (United States)
Richard N. Conner; James M. McCormick; Richard R. Schaefer; Daniel Saenz; D. Craig Rudolph
2001-01-01
During a study of red cockaded woodpecker (P icoides borealis) nesting in eastern Texas, we discovered a single breeding pair of woodpeckers with two simultaneous nests in nest trees that were 24 m apart. Incubation of eggs in each nest tree was at least 13 d and may have been as long as 16 d. The breeding male incubated and fed a nestling in one...
19. The Role of Non-Foraging Nests in Polydomous Wood Ant Colonies.
Science.gov (United States)
Ellis, Samuel; Robinson, Elva J H
2015-01-01
A colony of red wood ants can inhabit more than one spatially separated nest, in a strategy called polydomy. Some nests within these polydomous colonies have no foraging trails to aphid colonies in the canopy. In this study we identify and investigate the possible roles of non-foraging nests in polydomous colonies of the wood ant Formica lugubris. To investigate the role of non-foraging nests we: (i) monitored colonies for three years; (ii) observed the resources being transported between non-foraging nests and the rest of the colony; (iii) measured the amount of extra-nest activity around non-foraging and foraging nests. We used these datasets to investigate the extent to which non-foraging nests within polydomous colonies are acting as: part of the colony expansion process; hunting and scavenging specialists; brood-development specialists; seasonal foragers; or a selfish strategy exploiting the foraging effort of the rest of the colony. We found that, rather than having a specialised role, non-foraging nests are part of the process of colony expansion. Polydomous colonies expand by founding new nests in the area surrounding the existing nests. Nests founded near food begin foraging and become part of the colony; other nests are not founded near food sources and do not initially forage. Some of these non-foraging nests eventually begin foraging; others do not and are abandoned. This is a method of colony growth not available to colonies inhabiting a single nest, and may be an important advantage of the polydomous nesting strategy, allowing the colony to expand into profitable areas.
20. The Role of Non-Foraging Nests in Polydomous Wood Ant Colonies
OpenAIRE
Ellis, Samuel; Robinson, Elva J. H.
2015-01-01
A colony of red wood ants can inhabit more than one spatially separated nest, in a strategy called polydomy. Some nests within these polydomous colonies have no foraging trails to aphid colonies in the canopy. In this study we identify and investigate the possible roles of non-foraging nests in polydomous colonies of the wood ant Formica lugubris. To investigate the role of non-foraging nests we: (i) monitored colonies for three years; (ii) observed the resources being transported between non...
1. A voxelization approach to navigate through nested geometries
CERN Document Server
Harrison, Brent Andrew
2016-01-01
High energy physics experiment software typically implements a detailed description of the geometry of the relevant detector. As modern detectors increase in complexity, modelling them becomes more challenging. Typically such models are built as a nested hierarchy of O(10000) volumes reaching a depth of 10 - 20. It is desirable to develop data structures and algorithms which allow fast and efficient navigation though a given detector geometry model. We investigate the feasibility of voxelisation techniques to this end.
2. Nested Nanotherapeutics for Drug Synergy Enhancement in Breast Cancer Therapy
Science.gov (United States)
2014-09-01
different phases, but also partitioning. Modeling results suggest that release from the core and shell saturated at 46% and 92%, respectively...mammary fat pad, and received nested nanoparticles once a week for the duration of 3 weeks. As can be observed from the figure, control tumors grew...Blanco, E;* Serda, R.E.* The physiology of cardiovascular disease and innovative liposomal platforms for therapy. Int J Nanomedicine, 2013, 8, 629
3. Evaluation of nested PCR in diagnosis of fungal rhinosinusitis
OpenAIRE
2015-01-01
Background and Objective: Given the importance of rapid diagnosis for fungal rhinosinusitis, this study aimed to evaluate the use of nested PCR to identify Aspergillus and Mucor species in clinical samples from patients with suspected fungal rhinosinusitis.Methods: Functional endoscopic sinus surgery specimens were collected from 98 patients with rhinosinusitis from 2012 to 2013. All samples were ground and cultured on sabouraud dextrose agar. The isolated fungi were identified based on their...
4. Regional Model Nesting Within GFS Daily Forecasts Over West Africa
Science.gov (United States)
Druyan, Leonard M.; Fulakeza, Matthew; Lonergan, Patrick; Worrell, Ruben
2010-01-01
The study uses the RM3, the regional climate model at the Center for Climate Systems Research of Columbia University and the NASA/Goddard Institute for Space Studies (CCSR/GISS). The paper evaluates 30 48-hour RM3 weather forecasts over West Africa during September 2006 made on a 0.5 grid nested within 1 Global Forecast System (GFS) global forecasts. September 2006 was the Special Observing Period #3 of the African Monsoon Multidisciplinary Analysis (AMMA). Archived GFS initial conditions and lateral boundary conditions for the simulations from the US National Weather Service, National Oceanographic and Atmospheric Administration were interpolated four times daily. Results for precipitation forecasts are validated against Tropical Rainfall Measurement Mission (TRMM) satellite estimates and data from the Famine Early Warning System (FEWS), which includes rain gauge measurements, and forecasts of circulation are compared to reanalysis 2. Performance statistics for the precipitation forecasts include bias, root-mean-square errors and spatial correlation coefficients. The nested regional model forecasts are compared to GFS forecasts to gauge whether nesting provides additional realistic information. They are also compared to RM3 simulations driven by reanalysis 2, representing high potential skill forecasts, to gauge the sensitivity of results to lateral boundary conditions. Nested RM3/GFS forecasts generate excessive moisture advection toward West Africa, which in turn causes prodigious amounts of model precipitation. This problem is corrected by empirical adjustments in the preparation of lateral boundary conditions and initial conditions. The resulting modified simulations improve on the GFS precipitation forecasts, achieving time-space correlations with TRMM of 0.77 on the first day and 0.63 on the second day. One realtime RM3/GFS precipitation forecast made at and posted by the African Centre of Meteorological Application for Development (ACMAD) in Niamey, Niger
5. Nested sampling for materials: the case of hard spheres
OpenAIRE
Partay, Livia B.; Bartok, Albert P.; Csanyi, Gabor
2012-01-01
The recently introduced nested sampling algorithm allows the direct and efficient calculation of the partition function of atomistic systems. We demonstrate its applicability to condensed phase systems with periodic boundary conditions by studying the three dimensional hard sphere model. Having obtained the partition function, we show how easy it is to calculate the compressibility and the free energy as functions of the packing fraction and local order, verifying that the transition to cryst...
6. Sensitivitas dan Spesifisitas Nested Polymerase Chain Reaction untuk Mendeteksi DNA Coxiella burnetii (SENSITIVITY AND SPECIFICITY OF NESTED POLYMERASE CHAIN REACTION FOR DETECTION OF COXIELLA BURNETII DNA
Directory of Open Access Journals (Sweden)
Trioso Purnawarman
2014-04-01
Full Text Available Sensitivity and specificity of nested polymerase chain reaction (nested PCR to detect Coxiella burnetii(C. burnetii DNA were studied. The primer system which consists of external primers (OMP1 and OMP2and internal primers (OMP3 and OMP4, was designed from the nucleotide sequence of the com I geneencoding for 27 kDa outer membrane protein and used to specifically amplify a 501 bp and 438 bp fragment.This nested PCR assay was 50 fold more sensitive than that of using PCR external primer only. TheNested PCR has a detection limit as low as 300 pg/?l. Specificity studies showed that nested PCR onlydetected C. burnetii DNA and did not happened Brucella abortus, Escherichia coli, Pseudomonas aeruginosaand Campylobacter Jejuni DNA. Nested PCR has high senstively and specificaly diagnostic method of C.burnetii as agent of Q fever disease.
7. Nest sanitation through defecation: antifungal properties of wood cockroach feces
Science.gov (United States)
Rosengaus, Rebeca B.; Mead, Kerry; Du Comb, William S.; Benson, Ryan W.; Godoy, Veronica G.
2013-11-01
The wood cockroach Cryptocercus punctulatus nests as family units inside decayed wood, a substrate known for its high microbial load. We tested the hypothesis that defecation within their nests, a common occurrence in this species, reduces the probability of fungal development. Conidia of the entomopathogenic fungus, Metarhizium anisopliae, were incubated with crushed feces and subsequently plated on potato dextrose agar. Relative to controls, the viability of fungal conidia was significantly reduced following incubation with feces and was negatively correlated with incubation time. Although the cockroach's hindgut contained abundant β-1,3-glucanase activity, its feces had no detectable enzymatic function. Hence, these enzymes are unlikely the source of the fungistasis. Instead, the antifungal compound(s) of the feces involved heat-sensitive factor(s) of potential microbial origin. When feces were boiled or when they were subjected to ultraviolet radiation and subsequently incubated with conidia, viability was "rescued" and germination rates were similar to those of controls. Filtration experiments indicate that the fungistatic activity of feces results from chemical interference. Because Cryptocercidae cockroaches have been considered appropriate models to make inferences about the factors fostering the evolution of termite sociality, we suggest that nesting in microbe-rich environments likely selected for the coupling of intranest defecation and feces fungistasis in the common ancestor of wood cockroaches and termites. This might in turn have served as a preadaptation that prevented mycosis as these phylogenetically related taxa diverged and evolved respectively into subsocial and eusocial organizations.
8. Evaluation of nested PCR in diagnosis of fungal rhinosinusitis
Directory of Open Access Journals (Sweden)
2015-10-01
Full Text Available Background and Objective: Given the importance of rapid diagnosis for fungal rhinosinusitis, this study aimed to evaluate the use of nested PCR to identify Aspergillus and Mucor species in clinical samples from patients with suspected fungal rhinosinusitis.Methods: Functional endoscopic sinus surgery specimens were collected from 98 patients with rhinosinusitis from 2012 to 2013. All samples were ground and cultured on sabouraud dextrose agar. The isolated fungi were identified based on their macroscopic and microscopic features. Fungal DNA was extracted from the tissue samples and nested PCR was performedwith two sets of primers for Mucor and Aspergillus.Results: Direct microscopic showed that 5.1% contained fungal components and 9.2% exhibited growth of fungi in culture. The most common agents isolated were Aspergillus fumigatus (n= 3 , Aspergillus flavus (n=2, Penicillium sp (n=3 and Alternaria sp. (n=1. Mucor sp. was identified in the pathology smear from 1 patient. Positive results for fungal rhinosinusitis were obtained for a total of 10.2% by culture or pathology smear. Positive PCR results were obtained in 72 samples for Aspergillus and 31 samples for Mucor.Conclusion: Our results suggest that endoscopic sinus surgery specimens are not suitable for nested PCR, probably because of the accumulation of fungi that contaminate the environmental air. This drawback is a limiting factor for diagnosis with nasal cavity specimens. Therefore, molecular methods and conventional culture techniques are helpful complementarydiagnostic methods to detect fungal rhinosinusitis and determine appropriate management for these patients.
9. Design of nested Halbach cylinder arrays for magnetic refrigeration applications
Energy Technology Data Exchange (ETDEWEB)
Trevizoli, Paulo V., E-mail: [email protected]; Lozano, Jaime A.; Peixer, Guilherme F.; Barbosa Jr, Jader R.
2015-12-01
We present an experimentally validated analytical procedure to design nested Halbach cylinder arrays for magnetic cooling applications. The procedure aims at maximizing the magnetic flux density variation in the core of the array for a given set of design parameters, namely the inner diameter of the internal magnet, the air gap between the magnet cylinders, the number of segments of each magnet and the remanent flux density of the Nd{sub 2}Fe{sub 14}B magnet grade. The design procedure was assisted and verified by 3-D numerical modeling using a commercial software package. An important aspect of the optimal design is to maintain an uniform axial distribution of the magnetic flux density in the region of the inner gap occupied by the active magnetocaloric regenerator. An optimal nested Halbach cylinder array was manufactured and experimentally evaluated for the magnetic flux density in the inner gap. The analytically calculated magnetic flux density variation agreed to within 5.6% with the experimental value for the center point of the magnet gap. - Highlights: • An analytical procedure to design nested Halbach cylinder arrays is proposed. • An optimal magnet configuration was built based on the analytical procedure. • The procedure was validated with 3D COMSOL simulations and experimental data.
10. A Variable Neighborhood Search Algorithm for the Leather Nesting Problem
Directory of Open Access Journals (Sweden)
Cláudio Alves
2012-01-01
Full Text Available The leather nesting problem is a cutting and packing optimization problem that consists in finding the best layout for a set of irregular pieces within a natural leather hide with an irregular surface and contour. In this paper, we address a real application of this problem related to the production of car seats in the automotive industry. The high quality requirements imposed on these products combined with the heterogeneity of the leather hides make the problem very complex to solve in practice. Very few results are reported in the literature for the leather nesting problem. Furthermore, the majority of the approaches impose some additional constraints to the layouts related to the particular application that is considered. In this paper, we describe a variable neighborhood search algorithm for the general leather nesting problem. To evaluate the performance of our approaches, we conducted an extensive set of computational experiments on real instances. The results of these experiments are reported at the end of the paper.
11. A nested sampling particle filter for nonlinear data assimilation
KAUST Repository
Elsheikh, Ahmed H.
2014-04-15
We present an efficient nonlinear data assimilation filter that combines particle filtering with the nested sampling algorithm. Particle filters (PF) utilize a set of weighted particles as a discrete representation of probability distribution functions (PDF). These particles are propagated through the system dynamics and their weights are sequentially updated based on the likelihood of the observed data. Nested sampling (NS) is an efficient sampling algorithm that iteratively builds a discrete representation of the posterior distributions by focusing a set of particles to high-likelihood regions. This would allow the representation of the posterior PDF with a smaller number of particles and reduce the effects of the curse of dimensionality. The proposed nested sampling particle filter (NSPF) iteratively builds the posterior distribution by applying a constrained sampling from the prior distribution to obtain particles in high-likelihood regions of the search space, resulting in a reduction of the number of particles required for an efficient behaviour of particle filters. Numerical experiments with the 3-dimensional Lorenz63 and the 40-dimensional Lorenz96 models show that NSPF outperforms PF in accuracy with a relatively smaller number of particles. © 2013 Royal Meteorological Society.
12. Nested governance for effective REDD+: Institutional and political arguments
Directory of Open Access Journals (Sweden)
Prakash Kashwan
2014-08-01
Full Text Available Reducing Emissions from Deforestation and Forest Degradation and Forest Enhancement (REDD+ has become a central focus of global climate change mitigation efforts. Even though the international demand for forest-based carbon sequestration is the key driver of REDD+, forest protection strategies must be implemented on the ground. This cross-scale nature of REDD+ explains why scholars and policy makers increasingly favor nested governance arrangements over either fully centralized or fully decentralized REDD+ governance. The focus of the literature on nested REDD+ governance has mostly been on monitoring, reporting, and verification of carbon emission reductions across sub-national, national, and international levels. We build on Ostrom’s principle of ‘nested enterprises’ to argue that REDD+ must be designed to systematically and formally link national policy reforms with the organization and execution of sub-national (regional and local forest conservation efforts led by forest users. We also contribute new insights on the political dimensions of nestedness in REDD+, with important roles for inter-community forestry associations and forest rights movements.
13. Stigmergic construction and topochemical information shape ant nest architecture.
Science.gov (United States)
Khuong, Anaïs; Gautrais, Jacques; Perna, Andrea; Sbaï, Chaker; Combe, Maud; Kuntz, Pascale; Jost, Christian; Theraulaz, Guy
2016-02-01
The nests of social insects are not only impressive because of their sheer complexity but also because they are built from individuals whose work is not centrally coordinated. A key question is how groups of insects coordinate their building actions. Here, we use a combination of experimental and modeling approaches to investigate nest construction in the ant Lasius niger. We quantify the construction dynamics and the 3D structures built by ants. Then, we characterize individual behaviors and the interactions of ants with the structures they build. We show that two main interactions are involved in the coordination of building actions: (i) a stigmergic-based interaction that controls the amplification of depositions at some locations and is attributable to a pheromone added by ants to the building material; and (ii) a template-based interaction in which ants use their body size as a cue to control the height at which they start to build a roof from existing pillars. We then develop a 3D stochastic model based on these individual behaviors to analyze the effect of pheromone presence and strength on construction dynamics. We show that the model can quantitatively reproduce key features of construction dynamics, including a large-scale pattern of regularly spaced pillars, the formation and merging of caps over the pillars, and the remodeling of built structures. Finally, our model suggests that the lifetime of the pheromone is a highly influential parameter that controls the growth and form of nest architecture.
14. Do honeybees, Apis mellifera scutellata, regulate humidity in their nest?
Science.gov (United States)
Human, Hannelie; Nicolson, Sue W.; Dietemann, Vincent
2006-08-01
Honeybees are highly efficient at regulating the biophysical parameters of their hive according to colony needs. Thermoregulation has been the most extensively studied aspect of nest homeostasis. In contrast, little is known about how humidity is regulated in beehives, if at all. Although high humidity is necessary for brood development, regulation of this parameter by honeybee workers has not yet been demonstrated. In the past, humidity was measured too crudely for a regulation mechanism to be identified. We reassess this issue, using miniaturised data loggers that allow humidity measurements in natural situations and at several places in the nest. We present evidence that workers influence humidity in the hive. However, there are constraints on potential regulation mechanisms because humidity optima may vary in different locations of the nest. Humidity could also depend on variable external factors, such as water availability, which further impair the regulation. Moreover, there are trade-offs with the regulation of temperature and respiratory gas exchanges that can disrupt the establishment of optimal humidity levels. As a result, we argue that workers can only adjust humidity within sub-optimal limits.
15. The urban transportation plan and air pollution: the mythical dimension of a public debate in the Lille (France) urban area; Le plan de deplacements urbains et la pollution de l'air: la dimension mythique du debat public dans l'agglomeration lilloise
Energy Technology Data Exchange (ETDEWEB)
Bratosin, St. [GERICO, Groupement des Equipes de Recherche Intedisciplinaire en communication, UFR Infocom, Universite Charles-de-Gaulle, Lille 3, 59 - Roubaix (France)
2000-07-01
The urban transportation plan and air pollution: the mythical dimension of a public debate in the Lille (France) urban area. The paper highlights the conditions for the public production of the urban transportation plan as a means for controlling and reducing air pollution in a democratic context where - on behalf of liberty, transparency and the right to information - inconsistency becomes a claim to which the technicians and politicians in charge of developing decision-making tools are faced inescapably. More precisely, it is aimed at clarifying the mythical dimension of the public consultation process about the measures to be undertaken to reduce and control urban air pollution, which is an everyday reality with multiple and disconcerting facets directly related to urban trip reality within the framework of the urban transportation plan. Thus, that the layout and the organisation of the urban trip reality constitutes an approach based on a number of symbolic operations: the definition of the consultation object by multiple signification layers, reviewing the self-reliant 'objectivity' of the consultation as compared to the so-called 'subjectivity' of the participation, the elusive lag between the 'true' and the apparently 'true', the intensity with which the trips in the metropolis are presented at a prescribed time, the distance between the dream and the reality, the absence of causal analysis, the dysfunction as a reason... French rules governing debate in the public decision-making impose an attempt to gather in a same system the contradictory dimensions of representation and participation. The proposed analysis is based on a number of documents, interviews and observations - from 1996 to 1999 - concerning the procedure used for developing the urban transportation plan in the Lille metropolis. (author)
16. Switch to diester preen waxes may reduce avian nest predation by mammalian predators using olfactory cues
NARCIS (Netherlands)
Reneerkens, J.; Piersma, Th.; Sinninghe Damsté, J.S.
2005-01-01
It has long been recognised that nest depredation by olfactory-searching mammals greatly influences the reproductive success of ground-nesting birds. Yet adaptations of birds to diminish smell during nesting have rarely been investigated. Recently, a remarkable shift in the composition of uropygial
17. Nest survival of American Coots relative to grazing, burning, and water depths
Science.gov (United States)
Austin, Jane E.; Buhl, Deborah A.
2011-01-01
Water and emergent vegetation are key features influencing nest site selection and success for many marsh-nesting waterbirds. Wetland management practices such as grazing, burning, and water-level manipulations directly affect these features and can influence nest survival. We used model selection and before-after-control-impact approaches to evaluate the effects of water depth and four common land-management practices or treatments, i.e., summer grazing, fall grazing, fall burning, and idle (no active treatment) on nest survival of American coots (Fulica americana) nesting at Grays Lake, a large montane wetland in southeast Idaho. The best model included the variables year × treatment, and quadratic functions of date, water depth, and nest age; height of vegetation at the nest did not improve the best model. However, results from the before-after-control-impact analysis indicate that management practices affected nest success via vegetation and involved interactions of hydrology, residual vegetation, and habitat composition. Nest success in idled fields changed little between pre- and post-treatment periods, whereas nest success declined in fields that were grazed or burned, with the most dramatic declines the year following treatments. The importance of water depth may be amplified in this wetland system because of rapid water-level withdrawal during the nesting season. Water and land-use values for area ranchers, management for nesting waterbirds, and long-term wetland function are important considerations in management of water levels and vegetation.
Science.gov (United States)
Ely, C.R.; Pearce, J.M.; Ruess, Roger W.
2008-01-01
Lesser Canada Geese (Branta canadensis parvipes) are widespread throughout interior regions of Alaska and Canada, yet there have been no published studies documenting basic aspects of their nesting biology. We conducted a study to determine reproductive parameters of Lesser Canada Geese nesting along the Tanana River near the city of Fairbanks, in interior Alaska. Fieldwork was conducted in May of 2003, and consisted of locating nests along the riparian corridor between Fairbanks and Northpole, Alaska. Nests were found on gravel islands and shore habitats along the Tanana River, and were most commonly observed among driftwood logs associated with patches of alder (Alnus spp.) and willow (Salix spp.). Peak of nest initiation was 3-8 May, with a range from 27 April to 20 May; renesting was likely. Clutches ranged in size from 2 to 7 eggs and averaged 4.6 eggs. There was a negative correlation between clutch size and date of nest initiation. Egg size (mean mass = 128 g) was similar to other medium-sized Canada Geese. A positive correlation between egg size and clutch size was likely related to female age. Nineteen of 28 nests (68%) were active when visited; nests located on islands with nesting Mew Gulls (Larus canus) were more likely to be active than nests located elsewhere. Evidence at nest sites implicated Bald Eagles (Haliaeetus leucocephalus) and Red Foxes (Vulpes vulpes) as nest predators.
19. Microhabitat Conditions in Wyoming's Sage-Grouse Core Areas: Effects on Nest Site Selection and Success
National Research Council Canada - National Science Library
Dinkins, Jonathan B; Smith, Kurt T; Beck, Jeffrey L; Kirol, Christopher P; Pratt, Aaron C; Conover, Michael R
2016-01-01
.... Nest success was estimated from 924 nests with survival data. Sage-grouse selected nests with greater sagebrush cover and height, visual obstruction, and number of small gaps between shrubs (gap size ≥0.5 m and <1.0 m...
20. The Antsy Social Network: Determinants of Nest Structure and Arrangement in Asian Weaver Ants.
Science.gov (United States)
2016-01-01
Asian weaver ants (Oecophylla smaragdina) are arboreal ants that are known to form mutualistic complexes with their host trees. They are eusocial ants that build elaborate nests in the canopy in tropical areas. A colony comprises of multiple nests, usually on multiple trees, and the boundaries of the colony may be difficult to identify. However, they provide the ideal model for studying group living in invertebrates since there are a definite number of nests for a given substrate, the tree. Here, we briefly examine the structure of the nests and the processes involved in the construction and maintenance of these nests. We have described the spatial arrangement of weaver ant nests on trees in two distinct tropical clusters, a few hundred kilometres apart in India. Measurements were made for 13 trees with a total of 71 nests in the two field sites. We have considered a host of biotic and abiotic factors that may be crucial in determining the location of the nesting site by Asian weaver ants. Our results indicate that tree characteristics and architecture followed by leaf features help determine nest location in Asian weaver ants. While environmental factors may not be as influential to nest arrangement, they seem to be important determinants of nest structure. The parameters that may be considered in establishing the nests could be crucial in picking the evolutionary drivers for colonial living in social organisms.
1. On the nest of Cryptomys Hottentotus in the Kruger National Park.
Directory of Open Access Journals (Sweden)
M.Sc.(Rand, G. De Graaff
1962-05-01
Full Text Available This paper briefly describes the structure of a nest of the mole rat, Cryptomys hotfentotus. In the Pretoriuskop area this species uses the gifbol fBop/ione disticha, grass roots and the sekelbos (Dichrosfachys nyassana as the main material for nest construction. The presence of invertebrates in the nest (such as mites and beetles is mentioned.
2. Nest site selection in a hot desert : Trade-off between microclimate and predation risk?
NARCIS (Netherlands)
Tieleman, B. Irene; van Noordwijk, Hendrika J.; Williams, Joseph B.
2008-01-01
Nest placement affects the risk of predation on both eggs and incubating parents and determines the microclimate for incubation, two functions that may be in conflict, especially in hot deserts. We studied the roles of microclimate and nest predation on nest site selection by Hoopoe Larks (Alaemon a
3. Nested algorithms for optimal reservoir operation and their embedding in a decision support platform
NARCIS (Netherlands)
Delipetrev, B.
2016-01-01
Reservoir operation is a multi-objective optimization problem traditionally solved with dynamic programming (DP) and stochastic dynamic programming (SDP) algorithms. The thesis presents novel algorithms for optimal reservoir operation named nested DP (nDP), nested SDP (nSDP), nested reinforcement le
4. Male rock sparrows differentially allocate nest defence but not food provisioning to offspring
DEFF Research Database (Denmark)
Matessi, Giuliano; Carmagnani, Cristina; Griggio, Matteo
2009-01-01
of males paired to sham-manipulated controls. Nest defence was assessed by placing a dummy predator on the nest box. Males of ornament-reduced females defended the nest less but did not feed the chicks less than males paired to control females. Our results only partially support male differential...
5. Tactic changes in dusky frillgoby Bathygobius fuscus sneaker males: effects of body size and nest availability.
Science.gov (United States)
Takegaki, T; Kaneko, T; Matsumoto, Y
2013-02-01
Field and laboratory studies were conducted to examine the effects of nest availability and body size on changes in male mating tactics from sneaking to nest-holding in the dusky frillgoby Bathygobius fuscus. In the field, the body size of nest-holding males decreased from early to mid-breeding season, suggesting the possibility of a change in the tactics of sneaker males to nest-holding. Many sneaker males did not use vacant spawning nests even when size-matched nests were available, but they continued to reproduce as sneakers. Similarly, in aquarium experiments with available vacant nests, some sneaker males became nest-holders irrespective of their body size, but some did not. These results showed that nest availability is not a limiting factor for changes in tactics by sneaker males in this species. Because tactic-unchanged sneaker males were co-housed with larger nest-holding males in the tanks, the body size of nearby nest-holding males may have affected the decision to change tactics for sneaker males. Moreover, smaller individuals among tactic-changed males tended to spend more time until spawning, probably because they had relatively larger costs and smaller benefits of reproduction as nest-holding males compared to larger males.
6. Nest Survival of American Coots Relative to Grazing, Burning, and Water Depths
Directory of Open Access Journals (Sweden)
Jane E. Austin
2011-12-01
Full Text Available Water and emergent vegetation are key features influencing nest site selection and success for many marsh-nesting waterbirds. Wetland management practices such as grazing, burning, and water-level manipulations directly affect these features and can influence nest survival. We used model selection and before-after-control-impact approaches to evaluate the effects of water depth and four common land-management practices or treatments, i.e., summer grazing, fall grazing, fall burning, and idle (no active treatment on nest survival of American coots (Fulica americana nesting at Grays Lake, a large montane wetland in southeast Idaho. The best model included the variables year × treatment, and quadratic functions of date, water depth, and nest age; height of vegetation at the nest did not improve the best model. However, results from the before-after-control-impact analysis indicate that management practices affected nest success via vegetation and involved interactions of hydrology, residual vegetation, and habitat composition. Nest success in idled fields changed little between pre- and post-treatment periods, whereas nest success declined in fields that were grazed or burned, with the most dramatic declines the year following treatments. The importance of water depth may be amplified in this wetland system because of rapid water-level withdrawal during the nesting season. Water and land-use values for area ranchers, management for nesting waterbirds, and long-term wetland function are important considerations in management of water levels and vegetation.
7. 7 CFR 57.801 - Nest run or washed ungraded eggs.
Science.gov (United States)
2010-01-01
... 7 Agriculture 3 2010-01-01 2010-01-01 false Nest run or washed ungraded eggs. 57.801 Section 57... Identification of Restricted Eggs Or Egg Products Not Intended for Human Consumption § 57.801 Nest run or washed ungraded eggs. Nest run or washed ungraded eggs are exempt from the labeling provisions in §...
8. Survey of Coastal Nesting Colonies of Cormorants, Gulls, Night-Herons, Egrets, and Ibises in Massachusetts, 2006-08
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — State summary of nesting information for wading birds and other colonial nesting birds in Massachusetts during the 2006-2008 nesting season.
9. Evaluation of nest site preferences of a nest dismantler,the Hair-crested Drongo(Dicrurus hottentottus) in Dongzhai National Nature Reserve of central China
Institute of Scientific and Technical Information of China (English)
Andrew Cantrell; Lei Lv; Yong Wang; Jianqiang Li; Zhengwang Zhang
2016-01-01
Background:The Hair-crested Drongo(Dicrurus hottentottus) exhibits a unique nest-dismantling behavior after the fledging of the young.One hypothesis explaining this behavior is dismantling one’s own nest may reduce potential competition for nest sites in the following breeding season because suitable breeding habitat might be limited,and sites are often reused.Methods:By comparing the habitat features at nest and random locations,we determined the nest habitat preference of the Hair-crested Drongo within Dongzhai National Nature Reserve,Henan,China.We also compared habitat features with nesting success to determine if any trends could be detected.Results:We found that nest tree height,diameter at breast height,live crown ratio,tree rank,and presence of overstory were significantly higher at nesting locations than random locations;slope,leaf litter cover percentage and depth,presence of understory and midstory,and number of trees per hectare were significantly lower at nest sites than random sites.Drongos preferred to use some tree species,such as Metasequoia glyptostroboides,Castanea mollissima,and Pterocarya stenoptera for nesting.Failed nests were often associated with habitat with higher percentage of leaf litter on the ground.Conclusion:Our data support that selection of nest sites does occur for this species at this site and therefore support the hypothesis that breeding habitat limitation could be one of the driving forces for the development of the nestdismantling behavior in this species.
10. Power lines, roads, and avian nest survival: effects on predator identity and predation intensity.
Science.gov (United States)
DeGregorio, Brett A; Weatherhead, Patrick J; Sperry, Jinelle H
2014-05-01
1 Anthropogenic alteration of landscapes can affect avian nest success by influencing the abundance, distribution, and behavior of predators. Understanding avian nest predation risk necessitates understanding how landscapes affect predator distribution and behavior. 2 From a sample of 463 nests of 17 songbird species, we evaluated how landscape features (distance to forest edge, unpaved roads, and power lines) influenced daily nest survival. We also used video cameras to identify nest predators at 137 nest predation events and evaluated how landscape features influenced predator identity. Finally, we determined the abundance and distribution of several of the principal predators using surveys and radiotelemetry. 3 Distance to power lines was the best predictor of predator identity: predation by brown-headed cowbirds (Molothrus ater), corvids (Corvus sp. and Cyanocitta cristata), racers (Coluber constrictor), and coachwhips (Masticophis flagellum) increased with proximity to power lines, whereas predation by rat snakes (Elaphe obsoleta) and raptors decreased. In some cases, predator density may reliably indicate nest predation risk because racers, corvids, and cowbirds frequently used power line right-of-ways. 4 Of five bird species with enough nests to analyze individually, daily nest survival of only indigo buntings (Passerina cyanea) decreased with proximity to power lines, despite predation by most predators at our site being positively associated with power lines. For all nesting species combined, distance to unpaved road was the model that most influenced daily nest survival. This pattern is likely a consequence of rat snakes, the locally dominant nest predator (28% of predation events), rarely using power lines and associated areas. Instead, rat snakes were frequently associated with road edges, indicating that not all edges are functionally similar. 5 Our results suggest that interactions between predators and landscape features are likely to be specific to
11. Nest visits and capture events affect breeding success of Yellow-billed and Pacific loons
Science.gov (United States)
Uher-Koch, Brian D.; Schmutz, Joel A.; Wright, Kenneth G.
2015-01-01
Accurate estimates of breeding success are essential for understanding population dynamics and for managing populations. Unfortunately, research activities to collect these data can negatively impact the breeding success of the study species and bias estimates of breeding success. Despite the potential for negative impacts, few studies have documented the effect of capturing incubating adults on nest survival or compared nest survival following different capture methods. In this study we evaluate the impacts of investigator disturbance associated with captures and nest visits on nest survival of Yellow-billed Loons (Gavia adamsii) and Pacific Loons (Gavia pacifica) in the National Petroleum Reserve-Alaska (NPR-A), an area of conservation concern, in 2011–2013. In an effort to reduce capture-related nest failures, we developed a new suspended dive net technique to catch territorial aquatic birds while off their nests. We then compared nest survival following suspended dive net captures to bow-net trap captures of breeding adult loons. Daily nest survival following bow-net trap or suspended dive net capture was about 30% lower than when adults were not captured. The effect of captures on nest survival was similar between bow-net trap and suspended dive net capture methods. Nest visits without captures also negatively impacted nest survival, although less than captures. If not accounted for, nest visitation biased daily survival rates of nests downward 6%. Effects of investigator disturbance did not differ by species or between years. Our results suggest that any source of disturbance that displaces incubating adult loons could potentially reduce nest survival. To maximize breeding success, human disturbance factors should be limited near loon nests.
12. Effects of intraguild predators on nest-site selection by prey.
Science.gov (United States)
Huang, Wen-San; Pike, David A
2012-01-01
Nest-site selection involves tradeoffs between the risk of predation (on females and/or nests) and nest-site quality (microenvironment), and consequently suitable nesting sites are often in limited supply. Interactions with "classical" predators (e.g., those not competing for shared resources) can strongly influence nest-site selection, but whether intraguild predation also influences this behavior is unknown. We tested whether risk of predation from an intraguild predator [the diurnal scincid lizard Eutropis (Mabuya) longicaudata] influences nest-site selection by its prey (the nocturnal gecko Gekko hokouensis) on Orchid Island, Taiwan. These two species putatively compete for shared resources, including invertebrate prey and nesting microhabitat, but the larger E. longicaudata also predates G. hokouensis (but not its hard-shelled eggs). Both species nested within a concrete wall containing a series of drainage holes that have either one ("closed-in") or two openings ("open"). In allopatry, E. longicaudata preferred to nest within holes that were plugged by debris (thereby protecting eggs from water intrusion), whereas G. hokouensis selected holes that were open at both ends (facilitating escape from predators). When we experimentally excluded E. longicaudata from its preferred nesting area, G. hokouensis not only nested in higher abundances, but also modified its nest-site selection, such that communal nesting was more prevalent and both open and closed-in holes were used equally. Egg viability was unaffected by the choice of hole type, but was reduced slightly (by 7%) in the predator exclusion area (presumably due to higher local incubation temperatures). Our field experiment demonstrates that intraguild predators can directly influence the nest density of prey by altering maternal nest-site selection behavior, even when the predator and prey are active at different times of day and the eggs are not at risk of predation.
13. The effect of bubble nest size on sexual selection in wild Siamese fighting fish
Directory of Open Access Journals (Sweden)
Mullica Jaroensutasinee
2003-05-01
Full Text Available The effect of bubble nest size was tested on male contest and female preference in wild Siamese fighting fish, Betta splendens Regan, a sexually dimorphic fish that exhibits paternal care. Females presented with two potential mates of different bubble nest areas did not prefer larger bubble nest males. Larger bubble nest males were not more successful in male contests. There were no differences in fighting duration. Comparing agonistic behaviour between large and small bubble nest males, there were no differences between these two males concerning any agonistic behaviours during fighting.
14. Ecological aspects of nesting in Caiman crocodilus chiapasius (Bocourt 1876) in La Encrucijada Biosphere Reserve, Mexico
Energy Technology Data Exchange (ETDEWEB)
Gonzalez-Desales, G.A.; Monroy-Vilchis, O.; Charruau, P.; Zarco-Gonzalez, M.M.
2016-07-01
Studies on caiman, Caiman crocodilus chiapasius, in Mexico are scarce. The present study was conducted to evaluate the key characteristics regarding the reproductive ecology of caiman in Mexico. We conducted nest searches from April to September 2014. We observed that nests were built in June and that hatching occurred in September and October. The phase of the moon had an effect on nesting events. The height of the nest, the distance to the nearest tree, and the distance from the top of the nest to the first egg were related to hatching success and incubation temperature. (Author)
15. Larvae and Nests of Aculeate Hymenoptera (Hymenoptera: Aculeata) Nesting in Reed Galls Induced by Lipara spp. (Diptera: Chloropidae) with a Review of Species Recorded. Part II.
Science.gov (United States)
Astapenková, Alena; Heneberg, Petr
2017-01-01
The ability of aculeate Hymenoptera to utilize wetlands is poorly understood, and descriptions of their nests and developmental stages are largely absent. Here we present results based on our survey of hymenopterans using galls induced by Lipara spp. flies on common reed Phragmites australis in the years 2015–2016. We studied 20,704 galls, of which 9,446 were longitudinally cut and the brood from them reared in the laboratory, while the remaining 11,258 galls reared in rearing bags also in laboratory conditions. We recorded eight species that were previously not known to nest in reed galls: cuckoo wasps Chrysis rutilans and Trichrysis pumilionis, solitary wasps Stenodynerus chevrieranus and Stenodynerus clypeopictus, and bees Pseudoanthidium tenellum, Stelis punctulatissima, Hylaeus communis and Hylaeus confusus. Forty five species of Hymenoptera: Aculeata are known to be associated with reed galls, of which 36 make their nests there, and the other are six parasitoids of the family Chrysididae and three cuckoo bees of the genus Stelis. Of these species, Pemphredon fabricii and in southern Europe also Heriades rubicola are very common in reed galls, followed by Hylaeus pectoralis and two species of the genus Trypoxylon. We also found new host-parasite associations: Chrysis angustula in nests of Pemphredon fabricii, Chrysis rutilans in nests of Stenodynerus clypeopictus, Trichrysis pumilionis in nests of Trypoxylon deceptorium, and Stelis breviuscula in nests of Heriades rubicola. We provide new descriptions of the nests of seven species nesting in reed galls and morphology of mature larvae of eight species nesting in reed galls and two parasitoids and one nest cleptoparasite. The larvae are usually very similar to those of related species but possess characteristics that make them easy to distinguish from related species. Our results show that common reeds are not only expansive and harmful, but very important for many insect species associated with habitats
16. Higher nest predation risk in association with a top predator: mesopredator attraction?
Science.gov (United States)
Morosinotto, Chiara; Thomson, Robert L; Hänninen, Mikko; Korpimäki, Erkki
2012-10-01
Breeding close to top predators is a widespread reproductive strategy. Breeding animals may gain indirect benefits if proximity to top predators results in a reduction of predation due to suppression of mesopredators. We tested if passerine birds gain protection from mesopredators by nesting within territories of a top predator, the Ural owl (Strix uralensis). We placed nest boxes for pied flycatchers (Ficedula hypoleuca) in Ural owl nest sites and in control sites (currently unoccupied by owls). The nest boxes were designed so that nest predation risk could be altered (experimentally increased) after flycatcher settlement; we considered predation rate as a proxy of mesopredator abundance. Overall, we found higher nest predation rates in treatment than in control sites. Flycatcher laying date did not differ between sites, but smaller clutches were laid in treatment sites compared to controls, suggesting a response to perceived predation risk. Relative nest predation rate varied between years, being higher in owl nest sites in 2 years but similar in another; this variation might be indirectly influenced by vole abundance. Proximity to Ural owl nests might represent a risky habitat for passerines. High predation rates within owl territories could be because small mesopredators that do not directly threaten owl nests are attracted to owl nest sites. This could be explained if some mesopredators use owl territories to gain protection from their own predators, or if top predators and mesopredators independently seek similar habitats.
17. Nesting of Phrynops geoffroanus (Testudines: Chelidae on sandy beaches along the Upper Xingu River, Brazil
Directory of Open Access Journals (Sweden)
Paulo D. Ferreira Júnior
2011-10-01
Full Text Available This work presents the first data on incubation temperature of Phrynops geoffroanus (Schweigger, 1812 in a natural environment, and provides information on nest predation, hatching success and size of offspring born in the nests on sandy beaches along the Upper Xingu River. Thirty-one P. geoffroanus nests were found, of which eleven were completely predated, mainly by Cerdocyon thous (Linnaeus, 1766. Incubation was completed in nine out of the 17 nests protected by netting. The nests presented an average of 13.1 eggs and were distributed over the various geomorphological sectors of the nine sampled beaches. The size and weight of the hatchlings varied significantly between nests, and the incubation period in protected nests lasted for 76.5 days, less than reported for controlled incubation in the laboratory. Daily variation in incubation temperature in the three nests monitored for temperature was lower in those situated in fine sand sediments. Incubation temperature varied from 22 to 39 C and may have affected hatching success, which reached 60.8% in protected nests. Nest distribution in different geomorphological sectors indicated the plasticity of P. geoffroanus in terms of variation in nesting environment, which partly explains the species' broad geographical distribution.
18. Determining nest predators of the Least Bell's Vireo through point counts, tracking stations, and video photography
Science.gov (United States)
Peterson, Bonnie L.; Kus, Barbara E.; Deutschman, Douglas H.
2004-01-01
We compared three methods to determine nest predators of the Least Bell's Vireo (Vireo bellii pusillus) in San Diego County, California, during spring and summer 2000. Point counts and tracking stations were used to identify potential predators and video photography to document actual nest predators. Parental behavior at depredated nests was compared to that at successful nests to determine whether activity (frequency of trips to and from the nest) and singing vs. non-singing on the nest affected nest predation. Yellow-breasted Chats (Icteria virens) were the most abundant potential avian predator, followed by Western Scrub-Jays (Aphelocoma californica). Coyotes (Canis latrans) were abundant, with smaller mammalian predators occurring in low abundance. Cameras documented a 48% predation rate with scrub-jays as the major nest predators (67%), but Virginia opossums (Didelphis virginiana, 17%), gopher snakes (Pituophis melanoleucus, 8%) and Argentine ants (Linepithema humile, 8%) were also confirmed predators. Identification of potential predators from tracking stations and point counts demonstrated only moderate correspondence with actual nest predators. Parental behavior at the nest prior to depredation was not related to nest outcome.
19. Variation in the structure of bird nests between northern Manitoba and southeastern Ontario.
Directory of Open Access Journals (Sweden)
Carla A Crossman
Full Text Available Traits that converge in appearance under similar environmental conditions among phylogenetically independent lineages are thought to represent adaptations to local environments. We tested for convergence in nest morphology and composition of birds breeding in two ecologically different locations in Canada: Churchill in northern Manitoba and Elgin in southeastern Ontario. We examined nests from four families of passerine birds (Turdidae: Turdus, Parulidae: Dendroica, Emberizidae: Passerculus and Fringillidae: Carduelis where closely related populations or species breed in both locations. Nests of American Robins, Yellow Warblers, and Carduelis finches had heavier nest masses, and tended to have thicker nest-walls, in northern Manitoba compared with conspecifics or congenerics breeding in southeastern Ontario. Together, all species showed evidence for wider internal and external nest-cup diameters in northern Manitoba, while individual species showed varying patterns for internal nest-cup and external nest depths. American Robins, Yellow Warblers, and Carduelis finches in northern Manitoba achieved heavier nest masses in different ways. American Robins increased all materials in similar proportions, and Yellow Warblers and Common Redpolls used greater amounts of select materials. While changes in nest composition vary uniquely for each species, the pattern of larger nests in northern Manitoba compared to southeastern Ontario in three of our four phylogenetically-independent comparisons suggests that birds are adapting to similar selective pressures between locations.
20. Entering behavior of Gasteruption brachychaetum Schrottky (Hymenoptera, Gasteruptiidae into a nest of Hylaeus Fabricius (Hymenoptera, Colletidae
Directory of Open Access Journals (Sweden)
Antonio Carlos Cruz Macedo
2012-09-01
Full Text Available Nests of Hylaeus aff. guaraniticus (Schrottky, 1906 were parasited by females of Gasteruption brachychaetum Schrottky, 1906 in trap nests in São Paulo (Brazil. This is thefirst host record of a Gasteruptiidae in the Neotropical Region. The behavior of a G.brachychaetum female entering a host's nest is described as follows: an inquiline female hovered near the host's nest, landed and detected that a female of H. aff. guaraniticus was inside the nest, waited for the host female to fly out, entered backwards into the nest, remained there for almost six minutes, and then went out the nest. The development time of immature stages of G.brachychaetum varied between 16 and 299 days.
1. The use of artificial nests by weaver ants: a preliminary field observation
DEFF Research Database (Denmark)
Offenberg, Joachim
2014-01-01
populations or destroy colonies. The ants, however, show adaptive nesting behavior, which may mitigate storm impact. This study tested whether Oecophylla smaragdina was willing to use plastic bottles as safe artificial nesting sites, and whether adoption of artificial nests was seasonally related to harsh...... weather. Bottles were used for nesting throughout the stormy rainy season in a pomelo plantation with an open canopy, whereas in a mango plantation with a denser canopy the ants, after initial colonisation, left the bottles again at the end of the rainy season, especially in the calmer part...... of the plantation. This suggests that exposure to harsh weather triggered the use of artificial nests. It was also found that ants preferred to nest in bottles covered with aluminum foil compared to transparent bottles. These findings document an opportunistic nesting behavior of weaver ants and suggest...
2. Landscape-moderated bird nest predation in hedges and forest edges
Science.gov (United States)
Ludwig, Martin; Schlinkert, Hella; Holzschuh, Andrea; Fischer, Christina; Scherber, Christoph; Trnka, Alfréd; Tscharntke, Teja; Batáry, Péter
2012-11-01
Landscape-scale agricultural intensification has caused severe declines in biodiversity. Hedges and forest remnants may mitigate biodiversity loss by enhancing landscape heterogeneity and providing habitat to a wide range of species, including birds. However, nest predation, the major cause of reproductive failure of birds, has been shown to be higher in forest edges than in forest interiors. Little is known about how spatial arrangement (configuration) of hedges affects the avian nest predation. We performed an experiment with artificial ground and elevated nests (resembling yellowhammer and whitethroat nests) baited with quail and plasticine eggs. Nests were placed in three habitat types with different degrees of isolation from forests: forest edges, hedges connected to forests and hedges isolated from forests. Nest predation was highest in forest edges, lowest in hedges connected to forests and intermediate in isolated hedges. In the early breeding season, we found similar nest predation on ground and elevated nests, but in the late breeding season nest predation was higher on ground nests than on elevated nests. Small mammals were the main predators of ground nests and appeared to be responsible for the increase in predation from early to late breeding season, whereas the elevated nests were mainly depredated by small birds and small mammals. High predation pressure at forest edges was probably caused by both forest and open-landscape predators. The influence of forest predators may be lower at hedges, leading to lower predation pressure than in forest edges. Higher predation pressure in isolated than connected hedges might be an effect of concentration of predators in these isolated habitats. We conclude that landscape configuration of hedges is important in nest predation, with connected hedges allowing higher survival than isolated hedges and forest edges.
3. Locating chimpanzee nests and identifying fruiting trees with an unmanned aerial vehicle.
Science.gov (United States)
van Andel, Alexander C; Wich, Serge A; Boesch, Christophe; Koh, Lian Pin; Robbins, Martha M; Kelly, Joseph; Kuehl, Hjalmar S
2015-10-01
Monitoring of animal populations is essential for conservation management. Various techniques are available to assess spatiotemporal patterns of species distribution and abundance. Nest surveys are often used for monitoring great apes. Quickly developing technologies, including unmanned aerial vehicles (UAVs) can be used to complement these ground-based surveys, especially for covering large areas rapidly. Aerial surveys have been used successfully to detect the nests of orang-utans. It is unknown if such an approach is practical for African apes, which usually build their nests at lower heights, where they might be obscured by forest canopy. In this 2-month study, UAV-derived aerial imagery was used for two distinct purposes: testing the detectability of chimpanzee nests and identifying fruiting trees used by chimpanzees in Loango National Park (Gabon). Chimpanzee nest data were collected through two approaches: we located nests on the ground and then tried to detect them in UAV photos and vice versa. Ground surveys were conducted using line transects, reconnaissance trails, and opportunistic sampling during which we detected 116 individual nests in 28 nest groups. In complementary UAV images we detected 48% of the individual nests (68% of nest groups) in open coastal forests and 8% of individual nests (33% of nest groups) in closed canopy inland forests. The key factor for nest detectability in UAV imagery was canopy openness. Data on fruiting trees were collected from five line transects. In 122 UAV images 14 species of trees (N = 433) were identified, alongside 37 tree species (N = 205) in complementary ground surveys. Relative abundance of common tree species correlated between ground and UAV surveys. We conclude that UAVs have great potential as a rapid assessment tool for detecting chimpanzee presence in forest with open canopy and assessing fruit tree availability. UAVs may have limited applicability for nest detection in closed canopy forest.
4. Construction of arboreal nests by brown-nosed coatis, Nasua nasua (Carnivora: Procyonidae in the Brazilian Pantanal
Directory of Open Access Journals (Sweden)
Natalie Olifiers
2009-09-01
Full Text Available The construction of arboreal nests is rare among mammals in the order Carnivora. However, coatis (Procyonidae: Nasua Storr, 1780 build arboreal nests that are used for resting or birthing. Here we describe Nasua nasua (Linnaeus, 1766 nests located during a telemetry study of coatis in the Brazilian Pantanal. Coati nests were all "bird-like", that is, open nests having a semispherical shape. Nests were constructed of twigs, branches, and lianas sometimes interlaced with leaves. Nest volume was 30-50 cm³ and average nest height was approximately 9.5 m. Nests were found in open "cerrado" vegetation, along forest edges, or in interior "cordilheiras" forest. The reasons why coatis build such nests are unclear, but may relate to inter or intraspecific competition for nesting sites, litter size, thermoregulation, and predation avoidance.
5. Comprehensive Comparison between Empty Nest and Non-Empty Nest Elderly: A Cross-Sectional Study among Rural Populations in Northeast China
Directory of Open Access Journals (Sweden)
Ye Chang
2016-08-01
Full Text Available This study aimed to comprehensively compare the general characteristics, lifestyles, serum parameters, ultrasonic cardiogram (UCG parameters, depression, quality of life, and various comorbidities between empty nest and non-empty nest elderly among rural populations in northeast China. This analysis was based on our previous study which was conducted from January 2012 to August 2013, using a multistage, stratified, random cluster sampling scheme. The final analyzed sample consisted of 3208 participants aged no less than 60 years, which was further classified into three groups: non-empty nest group, empty nest group (living as a couple, and empty nest group (living alone. More than half of the participants were empty nest elderly (60.5%. There were no significant statistical differences for serum parameters, UCG parameters, lifestyles, dietary pattern, and scores of Patient Health Questionnaire-9 (PHQ-9 and World Health Organization Quality of Life questionnaire, abbreviated version (WHOQOL-BREF among the three groups. Empty nest elderly showed no more risk for comorbidities such as general obesity, abdominal obesity, hyperuricemia, hyperhomocysteinemia, diabetes, dyslipidemia, left atrial enlargement (LAE, and stroke. Our study indicated that empty nest elderly showed no more risk for depression, low quality of life and comorbidities such as general obesity, abdominal obesity, hyperuricemia, hyperhomocysteinemia, diabetes, dyslipidemia, LAE, and stroke among rural populations in northeast China.
6. A Minimally Invasive Method for Sampling Nest and Roost Cavities for Fungi: a Novel Approach to Identify the Fungi Associated with Cavity-Nesting Birds
Science.gov (United States)
Michelle A. Jusino; Daniel Lindner; John K. Cianchetti; Adam T. Grisé; Nicholas J. Brazee; Jeffrey R. Walters
2014-01-01
Relationships among cavity-nesting birds, trees, and wood decay fungi pose interesting management challenges and research questions in many systems. Ornithologists need to understand the relationships between cavity-nesting birds and fungi in order to understand the habitat requirements of these birds. Typically, researchers rely on fruiting body surveys to identify...
7. Influence of Nest Box Color and Release Sites on Osmia lignaria (Hymenoptera: Megachilidae) Reproductive Success in a Commercial Almond Orchard.
Science.gov (United States)
Artz, Derek R; Allan, Matthew J; Wardell, Gordon I; Pitts-Singer, Theresa L
2014-12-01
Intensively managed, commercial orchards offer resources for managed solitary bees within agricultural landscapes and provide a means to study bee dispersal patterns, spatial movement, nest establishment, and reproduction. In 2012, we studied the impact of 1) the color of nest boxes covaried with four nest box density treatments and 2) the number of bee release sites covaried with two nest box density treatments on the reproductive success of Osmia lignaria Say in a California almond orchard pollinated by a mixture of O. lignaria and Apis mellifera L. Nest box color influenced the number of nests, total cells, and cells with male and female brood. More nests and cells were produced in light blue nest boxes than in orange or yellow nest boxes. The covariate nest box density also had a significant effect on brood production. The number of release sites did not affect O. lignaria nesting and reproduction, but the number of cavities in nest boxes influenced reproduction. Overall, the color of nest boxes and their distribution, but not the number of release sites, can greatly affect O. lignaria nest establishment and reproductive success in a commercial almond orchard. The ability to locate nesting sites in a homogenous, large orchard landscape may also be facilitated by the higher frequency of nest boxes with low numbers of cavities, and by the ability to detect certain nest box colors that best contrast with the blooming trees. © 2014 Entomological Society of America.
8. Multiple nested basin boundaries in nonlinear driven oscillators☆
Science.gov (United States)
Zhang, Yongxiang; Xie, Xiangpeng; Luo, Guanwei
2017-03-01
A special type of basins of attraction for high-period coexisting attractors is investigated, which basin boundaries possess multiple nested structures in a driven oscillator. We analyze the global organization of basins and discuss the mechanism for the appearance of layered structures. The unstable periodic orbits and unstable limit cycle are also detected in the oscillator. The basin organization is governed by the ordering of regular saddles and the regular saddle connections are the interrupted by the unstable limit cycle. Wada basin boundary with different Wada number is discovered. Wada basin boundaries for the hidden and rare attractors are also verified.
9. Diffusion Combustion in a Tube-Nested Combustor
OpenAIRE
Tetsuji, Seko; Ryosuke, Matsumoto; Yoshitomo, Shintani; Isao, Ishihara; Mamoru, Ozawa
2004-01-01
An advanced-type compact water-tube boiler has been designed on the basis of the new concept of cooling flame by water-tube bank in the furnace, and is referred to as "tube-nested combustor". It realized drastic reduction in boiler size as well as in the NO_x emission. In this present study, aiming at further improvement of boiler efficiency and reduction of NO_x emission, the combustion characteristics in the furnace were investigated by using the test boiler of 0.5t/h steam output. Experime...
10. A Bayesian Network View on Nested Effects Models
Directory of Open Access Journals (Sweden)
Fröhlich Holger
2009-01-01
Full Text Available Nested effects models (NEMs are a class of probabilistic models that were designed to reconstruct a hidden signalling structure from a large set of observable effects caused by active interventions into the signalling pathway. We give a more flexible formulation of NEMs in the language of Bayesian networks. Our framework constitutes a natural generalization of the original NEM model, since it explicitly states the assumptions that are tacitly underlying the original version. Our approach gives rise to new learning methods for NEMs, which have been implemented in the /Bioconductor package nem. We validate these methods in a simulation study and apply them to a synthetic lethality dataset in yeast.
11. Rigorous Performance Bounds for Quadratic and Nested Dynamical Decoupling
CERN Document Server
Xia, Yuhou; Lidar, Daniel A
2011-01-01
We present rigorous performance bounds for the quadratic dynamical decoupling (QDD) pulse sequence which protects a qubit from general decoherence, and for its nested generalization to an arbitrary number of qubits. Our bounds apply under the assumption of instantaneous pulses and of bounded perturbing environment and qubit-environment Hamiltonians such as those realized by baths of nuclear spins in quantum dots. We prove that if the total sequence time is fixed then the trace-norm distance between the unperturbed and protected system states can be made arbitrarily small by increasing the number of applied pulses.
12. Stabilization of moduli in spacetime with nested warping
CERN Document Server
Arun, Mathew Thomas
2016-01-01
The absence, so far, of any graviton signatures at the LHC imposes severe constraints on the Randall-Sundrum scenario. Although a generalization to higher dimensions with nested warpings has been shown to avoid these constraints, apart from incorporating several other phenomenologically interesting features, moduli stabilization in such models has been an open question. We demonstrate here how both the moduli involved can be stabilized, employing slightly different mechanisms for the two branches of the theory. This also offers a dynamical mechanism to generate and stabilize the UED scale.
13. Nested cycles in large triangulations and crossing-critical graphs
CERN Document Server
Hernandez-Velez, Cesar; Thomas, Robin
2009-01-01
We show that every sufficiently large plane triangulation has a large collection of nested cycles that either are pairwise disjoint, or pairwise intersect in exactly one vertex, or pairwise intersect in exactly two vertices. We apply this result to show that for each fixed positive integer $k$, there are only finitely many $k$-crossing-critical simple graphs of average degree at least six. Combined with the recent constructions of crossing-critical graphs given by Bokal, this settles the question of for which numbers $q>0$ there is an infinite family of $k$-crossing-critical simple graphs of average degree $q$.
14. Application of termite nest for adsorption of Cr(VI).
Science.gov (United States)
Araújo, B R; Reis, J O M; Rezende, E I P; Mangrich, A S; Wisniewski, A; Dick, D P; Romão, L P C
2013-11-15
15. Parametric design of tri-axial nested Helmholtz coils.
Science.gov (United States)
Abbott, Jake J
2015-05-01
This paper provides an optimal parametric design for tri-axial nested Helmholtz coils, which are used to generate a uniform magnetic field with controllable magnitude and direction. Circular and square coils, both with square cross section, are considered. Practical considerations such as wire selection, wire-wrapping efficiency, wire bending radius, choice of power supply, and inductance and time response are included. Using the equations provided, a designer can quickly create an optimal set of custom coils to generate a specified field magnitude in the uniform-field region while maintaining specified accessibility to the central workspace. An example case study is included.
16. Giardia and Cryptosporidium spp. dissemination during wastewater treatment and comparative detection via immunofluorescence assay (IFA), nested polymerase chain reaction (nested PCR) and loop mediated isothermal amplification (LAMP).
Science.gov (United States)
Gallas-Lindemann, Carmen; Sotiriadou, Isaia; Plutzer, Judit; Noack, Michael J; Mahmoudi, Mohammad Reza; Karanis, Panagiotis
2016-06-01
Environmental water samples from the Lower Rhine area in Germany were investigated via immunofluorescence assays (IFAs), nested polymerase chain reaction (nested PCR) and loop-mediated isothermal amplification (LAMP) to detect the presence of Giardia spp. (n=185) and Cryptosporidium spp. (n=227). The samples were concentrated through filtration or flocculation, and oocysts were purified via centrifugation through a sucrose density gradient. For all samples, IFA was performed first, followed by DNA extraction for the nested PCR and LAMP assays. Giardia cysts were detected in 105 samples (56.8%) by IFA, 62 samples (33.5%) by nested PCR and 79 samples (42.7%) by LAMP. Cryptosporidium spp. were detected in 69 samples (30.4%) by IFA, 95 samples (41.9%) by nested PCR and 99 samples (43.6%) by LAMP. According to these results, the three detection methods are complementary for monitoring Giardia and Cryptosporidium in environmental waters.
17. Catastrophic health expenditure: a comparative analysis of empty-nest and non-empty-nest households with seniors in Shandong, China
Science.gov (United States)
Yang, Tingting; Chu, Jie; Zhou, Chengchao; Medina, Alexis; Li, Cuicui; Jiang, Shan; Zheng, Wengui; Sun, Liyuan; Liu, Jing
2016-01-01
Objective The aim of this study was to compare the catastrophic health expenditure (CHE) prevalence and its determinants between empty-nest and non-empty-nest elderly households. Setting Shandong province of China. Participants A total of 2761 elderly households are included in the analysis. Results CHE incidence among elderly households was 44.9%. The CHE incidence of empty-nest singles (59.3%, p=0.000, OR=3.19) and empty-nest couples (52.9%, p=0.000, OR=2.45) are both statistically higher than that of non-empty-nest elderly households (31.4%). An inverse association was observed between CHE incidence and income level in all elderly household types. Factors including 1 or more household elderly members with non-communicable chronic diseases in the past 6 months, 1 or more elderly household members being hospitalised in the past year and lower household income, are significant risk factors for CHE in all 3 household types (p<0.05). Health insurance status was found to be a significant determinant of CHE among empty-nest singles and non-empty-nest households (p<0.05). Conclusions CHE incidence among elderly households is high in China. Empty-nest households are at higher risk for CHE than non-empty-nest households. Based on these findings, we suggest that special insurance be developed to broaden the coverage of health services and heighten the reimbursement rate for empty-nest elderly in the existing health insurance schemes. Financial and social protection interventions are also essential for identified at-risk subgroups among different types of elderly households. PMID:27381206
18. Are nest sites actively chosen? Testing a common assumption for three non-resource limited birds
Science.gov (United States)
Goodenough, A. E.; Elliot, S. L.; Hart, A. G.
2009-09-01
Many widely-accepted ecological concepts are simplified assumptions about complex situations that remain largely untested. One example is the assumption that nest-building species choose nest sites actively when they are not resource limited. This assumption has seen little direct empirical testing: most studies on nest-site selection simply assume that sites are chosen actively (and seek explanations for such behaviour) without considering that sites may be selected randomly. We used 15 years of data from a nestbox scheme in the UK to test the assumption of active nest-site choice in three cavity-nesting bird species that differ in breeding and migratory strategy: blue tit ( Cyanistes caeruleus), great tit ( Parus major) and pied flycatcher ( Ficedula hypoleuca). Nest-site selection was non-random (implying active nest-site choice) for blue and great tits, but not for pied flycatchers. We also considered the relative importance of year-specific and site-specific factors in determining occupation of nest sites. Site-specific factors were more important than year-specific factors for the tit species, while the reverse was true for pied flycatchers. Our results show that nest-site selection, in birds at least, is not always the result of active choice, such that choice should not be assumed automatically in studies of nesting behaviour. We use this example to highlight the need to test key ecological assumptions empirically, and the importance of doing so across taxa rather than for single "model" species.
19. Retirement investment theory explains patterns in songbird nest-site choice
Science.gov (United States)
Streby, Henry M.; Refsnider, Jeanine M.; Peterson, Sean M.; Andersen, David E.
2014-01-01
When opposing evolutionary selection pressures act on a behavioural trait, the result is often stabilizing selection for an intermediate optimal phenotype, with deviations from the predicted optimum attributed to tracking a moving target, development of behavioural syndromes or shifts in riskiness over an individual's lifetime. We investigated nest-site choice by female golden-winged warblers, and the selection pressures acting on that choice by two fitness components, nest success and fledgling survival. We observed strong and consistent opposing selection pressures on nest-site choice for maximizing these two fitness components, and an abrupt, within-season switch in the fitness component birds prioritize via nest-site choice, dependent on the time remaining for additional nesting attempts. We found that females consistently deviated from the predicted optimal behaviour when choosing nest sites because they can make multiple attempts at one fitness component, nest success, but only one attempt at the subsequent component, fledgling survival. Our results demonstrate a unique natural strategy for balancing opposing selection pressures to maximize total fitness. This time-dependent switch from high to low risk tolerance in nest-site choice maximizes songbird fitness in the same way a well-timed switch in human investor risk tolerance can maximize one's nest egg at retirement. Our results also provide strong evidence for the adaptive nature of songbird nest-site choice, which we suggest has been elusive primarily due to a lack of consideration for fledgling survival.
20. Nesting ecology of Nile crocodiles (Crocodylus niloticus in the Olifants River, Kruger National Park
Directory of Open Access Journals (Sweden)
D.G.J. Swanepoel
2000-07-01
Full Text Available Data on the nesting behaviour of Crocodylus niloticus along the Olifants River in the Kruger National Park were collected over a period of six years (1993 to 1998. A total of 165 nests were investigated for soil type, exposure to sunlight, distance to and above water, presence of other nests and vegetation. An attempt was made to determine important factors in the placement of nests, and exposure to sunlight, vegetation and distance to water seemed to be crucial in selecting a nesting site. During the last two seasons 20 nests were opened and the nest contents recorded. Some 795 eggs were measured and the data compared to similar studies in Africa. No significant differences were found. A strong correlation was found between egg mass, length and female size with larger females producing larger eggs. Rainfall influenced the size of nesting females as only larger females (>3 m TL nested during the dry year. Breeding females along the Olifants were overall larger (TL than in Zimbabwe with 2.1 m as the smallest and 4.1 as the largest females that nested.
1. Nest platforms increase aggressive behavior in common loons
Science.gov (United States)
Mager, John N., III; Walcott, Charles; Piper, Walter H.
2008-02-01
Artificial manipulations of habitat, such as those that incorporate adding nesting boxes or platforms for birds, often enhance the breeding success of threatened animals. However, such alterations are likely to have unintended behavioral and ecological effects that might negatively impact the target species or others in its community. We conducted a controlled study to investigate the effect of artificial nesting platforms on aggressive behavior and reproductive success of male common loons ( Gavia immer). Males residing on territories to which platforms were added produced longer territorial “yodels” (reflecting willingness to escalate a contest), experienced increased levels of confrontation and aggression with territorial intruders, and experienced increased rates of territorial displacement by intruders. Surprisingly, males of treatment territories also experienced lower productivity. Therefore, in addition to providing novel empirical support of sequential assessment models of animal contests that predict contest escalation with increasing resource quality, this study is one of a few to show that tools used to mitigate habitat loss can negatively impact reproductive fitness in a threatened species.
2. Demonstration of EnergyNest thermal energy storage (TES) technology
Science.gov (United States)
Hoivik, Nils; Greiner, Christopher; Tirado, Eva Bellido; Barragan, Juan; Bergan, Pâl; Skeie, Geir; Blanco, Pablo; Calvet, Nicolas
2017-06-01
This paper presents the experimental results from the EnergyNest 2 × 500 kWhth thermal energy storage (TES) pilot system installed at Masdar Institute of Science & Technology Solar Platform. Measured data are shown and compared to simulations using a specially developed computer program to verify the stability and performance of the TES. The TES is based on a solid-state concrete storage medium (HEATCRETE®) with integrated steel tube heat exchangers cast into the concrete. The unique concrete recipe used in the TES has been developed in collaboration with Heidelberg Cement; this material has significantly higher thermal conductivity compared to regular concrete implying very effective heat transfer, at the same time being chemically stable up to 450 °C. The demonstrated and measured performance of the TES matches the predictions based on simulations, and proves the operational feasibility of the EnergyNest concrete-based TES. A further case study is analyzed where a large-scale TES system presented in this article is compared to two-tank indirect molten salt technology.
3. Nested sampling as a tool for LISA data analysis
Energy Technology Data Exchange (ETDEWEB)
Gair, Jonathan R [Institute of Astronomy, Madingley Road, CB3 0HA, Cambridge (United Kingdom); Feroz, Farhan; Graff, Philip; Hobson, Michael P [Astrophysics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Babak, Stanislav; Petiteau, Antoine [Max-Planck-Institut fuer Gravitationsphysik, Am Muehlenberg 1, 14476, Potsdam (Germany); Porter, Edward K, E-mail: [email protected] [APC, UMR 7164, Universite Paris 7 Denis Diderot, 10, rue Alice Domon et Leonie Duquet, 75205 Paris Cedex 13 (France)
2010-05-01
Nested sampling is a technique for efficiently computing the probability of a data set under a particular hypothesis, also called the Bayesian Evidence or Marginal Likelihood, and for evaluating the posterior. MULTINEST is a multi-modal nested sampling algorithm which has been designed to efficiently explore and characterize posterior probability surfaces containing multiple secondary solutions. We have applied the MULTINEST algorithm to a number of problems in gravitational wave data analysis. In this article, we describe the algorithm and present results for several applications of the algorithm to analysis of mock LISA data. We summarise recently published results for a test case in which we searched for two non-spinning black hole binary merger signals in simulated LISA data. We also describe results obtained with MULTINEST in the most recent round of the Mock LISA Data Challenge (MLDC), in which the algorithm was used to search for and characterise both spinning supermassive black hole binary inspirals and bursts from cosmic string cusps. In all these applications, the algorithm found the correct number of signals and efficiently recovered the posterior probability distribution. Moreover, in most cases the waveform corresponding to the best a-posteriori parameters had an overlap in excess of 99% with the true signal.
4. Wyner-Ziv Coding Based on Multidimensional Nested Lattices
CERN Document Server
Ling, Cong; Belfiore, Jean-Claude
2011-01-01
Distributed source coding (DSC) addresses the compression of correlated sources without communication links among them. This paper is concerned with the Wyner-Ziv problem: coding of an information source with side information available only at the decoder in the form of a noisy version of the source. Both the theoretical analysis and code design are addressed in the framework of multi-dimensional nested lattice coding (NLC). For theoretical analysis, accurate computation of the rate-distortion function is given under the high-resolution assumption, and a new upper bound using the derivative of the theta series is derived. For practical code design, several techniques with low complexity are proposed. Compared to the existing Slepian-Wolf coded nested quantization (SWC-NQ) for Wyner-Ziv coding based on one or two-dimensional lattices, our proposed multi-dimensional NLC can offer better performance at arguably lower complexity, since it does not require the second stage of Slepian-Wolf coding.
5. Nested Association Mapping for Identification of Functional Markers
Science.gov (United States)
Guo, Baohong; Sleper, David A.; Beavis, William D.
2010-01-01
Identification of functional markers (FMs) provides information about the genetic architecture underlying complex traits. An approach that combines the strengths of linkage and association mapping, referred to as nested association mapping (NAM), has been proposed to identify FMs in many plant species. The ability to identify and resolve FMs for complex traits depends upon a number of factors including frequency of FM alleles, magnitudes of their genetic effects, disequilibrium among functional and nonfunctional markers, statistical analysis methods, and mating design. The statistical characteristics of power, accuracy, and precision to identify FMs with a NAM population were investigated using three simulation studies. The simulated data sets utilized publicly available genetic sequences and simulated FMs were identified using least-squares variable selection methods. Results indicate that FMs with simple additive genetic effects that contribute at least 5% to the phenotypic variability in at least five segregating families of a NAM population consisting of recombinant inbred progeny derived from 28 matings with a single reference inbred will have adequate power to accurately and precisely identify FMs. This resolution and power are possible even for genetic architectures consisting of disequilibrium among multiple functional and nonfunctional markers in the same genomic region, although the resolution of FMs will deteriorate rapidly if more than two FMs are tightly linked within the same amplicon. Finally, nested mating designs involving several reference parents will have a greater likelihood of resolving FMs than single reference designs. PMID:20551444
6. Nested PCR for specific diagnosis of Taenia solium taeniasis.
Science.gov (United States)
Mayta, Holger; Gilman, Robert H; Prendergast, Emily; Castillo, Janeth P; Tinoco, Yeny O; Garcia, Hector H; Gonzalez, Armando E; Sterling, Charles R
2008-01-01
Taeniasis due to Taenia solium is a disease with important public health consequences, since the larval stage is not exclusive to the animal intermediate, the pig, but also infects humans, causing neurocysticercosis. Early diagnosis and treatment of T. solium tapeworm carriers is important to prevent human cysticercosis. Current diagnosis based on microscopic observation of eggs lacks both sensitivity and specificity. In the present study, a nested-PCR assay targeting the Tso31 gene was developed for the specific diagnosis of taeniasis due to T. solium. Initial specificity and sensitivity testing was performed using stored known T. solium-positive and -negative samples. The assay was further analyzed under field conditions by conducting a case-control study of pretreatment stool samples collected from a population in an area of endemicity. Using the archived samples, the assay showed 97% (31/32) sensitivity and 100% (123/123) specificity. Under field conditions, the assay had 100% sensitivity and specificity using microscopy/enzyme-linked immunosorbent assay coproantigen testing as the gold standards. The Tso31 nested PCR described here might be a useful tool for the early diagnosis and prevention of taeniasis/cysticercosis.
7. Sociable Weavers Increase Cooperative Nest Construction after Suffering Aggression.
Science.gov (United States)
Leighton, Gavin M; Meiden, Laura Vander
2016-01-01
The major transitions in evolution rely on the formation of stable groups that are composed of previously independent units, and the stability of these groups requires both cooperation and reduced conflict. Conflict over group resources may be common, as suggested by work in both cichlids and humans that has investigated how societies resolve conflict regarding investment in group resources, i.e. public goods. We investigated whether sociable weavers (Philetairus socius) use aggressive behaviors to modulate the cooperative behavior of group mates. We find that the individuals that build the communal thatch of the nest, i.e. the individuals most at risk of exploitation, are the most aggressive individuals. We show that individuals that invest in interior chamber maintenance, possibly a more selfish behavior, suffer relatively more aggression. After suffering aggression individuals significantly increase cooperative construction of the communal nest thatch. We show that cooperative individuals target aggression towards selfish individuals, and the individuals suffering aggression perform cooperative behaviors subsequent to suffering aggression. In addition to other evolutionary mechanisms, these results suggest that aggression, possibly via the pay-to-stay mechanism, is possibly being used to maintain a public good.
8. Linking snake habitat use to nest predation risk in grassland birds: the dangers of shrub cover.
Science.gov (United States)
Klug, Page E; Jackrel, Sara L; With, Kimberly A
2010-03-01
Extremes in rangeland management, varying from too-frequent fire and intensive grazing to the suppression of both, threaten rangeland ecosystems worldwide. Intensive fire and grazing denude and homogenize vegetation whereas their suppression increases woody cover. Although habitat loss is implicated in grassland bird declines, degradation through intensive management or neglect also decreases breeding habitat and may reduce nesting success through increased rates of nest predation. Snakes are important nest predators, but little is known about how habitat use in snakes relates to predation risk for grassland birds nesting within tallgrass prairie subjected to different grazing and fire frequencies. We evaluated nest survival in the context of habitat used by nesting songbirds and two bird-eating snakes, the eastern yellowbelly racer Coluber constrictor flaviventris and Great Plains ratsnake Pantherophis emoryi. Daily nest survival rates decreased with increasing shrub cover and decreasing vegetation height, which characterize grasslands that have been neglected or intensively managed, respectively. Discriminant function analysis revealed that snake habitats were characterized by higher shrub cover, whereas successful nests were more likely to occur in areas with tall grass and forbs but reduced shrub cover. Because snakes often use shrub habitat, birds nesting in areas with increased shrub cover may be at higher risk of nest predation by snakes in addition to other predators known to use shrub habitat (e.g., mid-sized carnivores and avian predators). Depredated nests also occurred outside the discriminant space of the snakes, indicating that other predators (e.g., ground squirrels Spermophilus spp. and bullsnakes Pituophis catenifer) may be important in areas with denuded cover. Targeted removal of shrubs may increase nest success by minimizing the activity of nest predators attracted to shrub cover.
9. Bird nest predation in a southern Tunisian oasis habitat: No evidence of “edge effect”
Science.gov (United States)
Boukhriss, Jihen; Selmi, Slaheddine; Nouira, Saïd
2009-03-01
Numerous ornithological studies conducted in patchy habitats have linked high intensity of nest predation with habitat edges. This "edge effect" hypothesis was primarily investigated in temperate, boreal and tropical fragmented forests, and there is a need for investigations from different habitat systems. Here we provide the results of one study on bird nest predation in relation to edge context in one oasis in southern Tunisia. Our aim was to assess the importance of nest predation as a source of nest failure in the studied oasis and to test if the edge effect hypothesis applies in this habitat system. We found that although predation represents an important source of nest failure in all studied species, the edge effect hypothesis does not seem to apply in the studied oasis. Indeed, daily nest predation rate did not vary with edge context for all studied species, which could be explained by the fact that nest predator guild is mainly composed of small species that use oasis interior and edges in similar ways. The effects of predators coming from the surrounding areas do not seem to significantly increase nest predation rates in oasis edges compared to oasis interior. We also found that nest predation rates were similar for all bird species, suggesting that among-species differences in nest concealment and nesting behaviour did not seem to account for nest survival in the studied oasis. However, further more detailed species-level studies are needed to test this hypothesis and to identify more accurately the determinants of nest predation in the oasis habitat.
10. Nesting ecology of Chelonia mydas Testudines: Cheloniidae on the Guanahacabibes Peninsula, Cuba
Directory of Open Access Journals (Sweden)
Julia Azanza Ricardo
2013-12-01
Full Text Available The nesting colony of green sea turtles Chelonia mydas at Guanahacabibes Peninsula Biosphere Reserve and National Park is one of the largest in the Cuban archipelago; however, little information about its nesting ecology is available. Temporal and spatial variation in nesting and reproductive success as well as morphometric characteristics of gravid females were used to ecologically characterize this colony. Nine beaches of the Southernmost coast of Guanahacabibes Peninsula were monitored for 14 years 1998-2012 to determine green turtle nesting activity, from May to September peak nesting season in this area. Beach dimensions were measured to determine nest density using the length and the area. Afterward the beaches were divided in two categories, index and secondary. Females were measured and tagged to compare new tagged females 823 with returning tagged females 140. Remigration interval was also determined. Temporal variation was identified as the annual number of nesting emergences and oviposits per female, with apparent peaks in reproductive activity on a biennial cycle in the first six years followed by periods of annual increase in nest number 2003-2008 and periods of decreasing number of nests 2010-2012. We also found intra-seasonal variation with the highest nesting activity in July, particularly in the second half of the month. The peak emergence time was 22:00-02:00hr. In terms of spatial variation, smaller beaches had the highest nest density and nesting was more frequent 6-9m from the high tide line, where hatchling production was maximized although hatchling success was high on average, above 80. Morphometric analysis of females was made and newly tagged turtles were smaller on average than remigrants. Our results are only a first attempt at characterizing Guanahacabibes populations but have great value for establishing conservation priorities within the context of national management plans, and for efficient monitoring and
11. Nesting ecology of Chelonia mydas (Testudines: Cheloniidae) on the Guanahacabibes Peninsula, Cuba.
Science.gov (United States)
Azanza Ricardo, Julia; Ibarra Martín, Maria E; González Sansón, Gaspar; Abreu Grobois, F Alberto; Eckert, Karen L; Espinosa López, Georgina; Oyama, Ken
2013-12-01
The nesting colony of green sea turtles (Chelonia mydas) at Guanahacabibes Peninsula Biosphere Reserve and National Park is one of the largest in the Cuban archipelago; however, little information about its nesting ecology is available. Temporal and spatial variation in nesting and reproductive success as well as morphometric characteristics of gravid females were used to ecologically characterize this colony. Nine beaches of the Southernmost coast of Guanahacabibes Peninsula were monitored for 14 years (1998-2012) to determine green turtle nesting activity, from May to September (peak nesting season in this area). Beach dimensions were measured to determine nest density using the length and the area. Afterward the beaches were divided in two categories, index and secondary. Females were measured and tagged to compare new tagged females (823) with returning tagged females (140). Remigration interval was also determined. Temporal variation was identified as the annual number of nesting emergences and oviposits per female, with apparent peaks in reproductive activity on a biennial cycle in the first six years followed by periods of annual increase in nest number (2003-2008) and periods of decreasing number of nests (2010-2012). We also found intra-seasonal variation with the highest nesting activity in July, particularly in the second half of the month. The peak emergence time was 22:00-02:00 hr. In terms of spatial variation, smaller beaches had the highest nest density and nesting was more frequent 6-9m from the high tide line, where hatchling production was maximized although hatchling success was high on average, above 80%. Morphometric analysis of females was made and newly tagged turtles were smaller on average than remigrants. Our results are only a first attempt at characterizing Guanahacabibes' populations but have great value for establishing conservation priorities within the context of national management plans, and for efficient monitoring and protection
12. Evaluating nest supplementation as a recovery strategy for the endangered rodents of the Florida Keys
Science.gov (United States)
Cove, Michael V.; Simons, Theodore R.; Gardner, Beth; Maurer, Andrew S.; O'Connell, Allan F.
2017-01-01
The Key Largo woodrat (Neotoma floridana smalli) and Key Largo cotton mouse (Peromyscus gossypinus allapaticola) are federally endangered subspecies endemic to the tropical hardwood hammocks of Key Largo, Florida. Woodrats are considered generalists in habitat and diet, yet a steady decline in natural stick nests and capture rates over the past several decades suggests that they are limited by the availability of nesting habitat due to habitat loss and fragmentation. The more specialized Key Largo cotton mouse appears to rely on old growth hammock, a habitat type that is rare following past land clearing. In 2004, the U.S. Fish and Wildlife Service started building supplemental nest structures to restore habitat quality and connectivity for these endangered rodents, but nest use requires evaluation. We used camera traps and occupancy models to evaluate the factors influencing woodrat and cotton mouse use of the supplemental nests. We detected woodrats at 65 and cotton mice at 175 of 284 sampled nest structures, with co-occurrence at 38 nests. Woodrat nest use followed a gradient from low nest use in the north to high nest use in the south, which might relate to the proximity of free-ranging domestic cat (Felis catus) colonies in residential developments. Cotton mouse nest use, however, was related positively to mature hammock and related negatively to disturbed areas (e.g. scarified lands). The two species occurred independently of each other. Stick-stacking behavior was observed at supplemental nests and, although it was correlated with detection of woodrats, it was not a strong predictor of their occurrence. We suggest that nest supplementation can be an important tool for species recovery as habitat quality continues to improve with succession.
13. Depredation of common eider, Somateria mollissima, nests on a central Beaufort Sea barrier island: A case where no one wins
Science.gov (United States)
Reed, J.A.; Lacroix, D.L.; Flint, P.L.
2007-01-01
Along the central Beaufort Sea, Pacific Common Eiders (Somateria mollissima v-nigra) nest on unvegetated, barrier islands; often near nesting Glaucous Gulls (Larus hyperboreus). Nest-site choice likely reflects a strategy of predator avoidance: nesting on islands to avoid mammalian predators and near territorial gulls to avoid other avian predators. We observed a nesting colony of Common Eiders from first nest initiation through nesting termination on Egg Island near Prudhoe Bay, Alaska (2002 - 2003). Resident gulls depredated many eider nests, mostly during initiation. All nests failed when an Arctic Fox (Alopex lagopus) visited the island and flushed hens from their nests, exposing the eggs to depredation by the fox and gulls (resident and non-resident). Common Eiders actively defended nests from gulls, but not from foxes. Likely all three species (i.e., eiders, gulls, and foxes) ultimately achieved negligible benefit from their nest-site selection or predatory activity: (a) island nesting provided no safety from mammalian predators for eiders or gulls, (b) for Common Eiders, nesting near gulls increased egg loss, (c) for Glaucous Gulls, nesting near colonial eiders may have reduced nest success by attracting the fox, and (d) for Arctic Foxes, the depredation was of questionable value, as most eggs were cached and probably not recoverable (due to damage from fall storms). Thus, the predator-prey interactions we observed appear to be a case where little or no fitness advantage was realized by any of the species involved.
14. The distribution and nest-site preference of Apis dorsata binghami at Maros Forest, South Sulawesi, Indonesia
Directory of Open Access Journals (Sweden)
2016-12-01
Full Text Available The giant honey bee, Apis dorsata binghami is subspecies of Apis dorsata. This species of bee was only found in Sulawesi and its surrounding islands. This study is aimed to study the distribution and characteristics of nest and nesting trees, nesting behavior of Apis dorsata binghami in the forests of Maros, South Sulawesi, Indonesia. The distributions of nests were observed using a survey method to record the species and characteristics of nesting trees, as well as the conditions around the nest. Results showed that 102 nests (17 active nests, 85 abandoned combs of A. d. binghami were found. We found 34 species belong to 27 genera in 17 families of plants as nesting sites of giant honey bee. The common tree species used as nesting sites were Ficus subulata (Moraceae, Adenanthera sp. (Fabaceae, Spondias pinnata (Anacardiaceae, Artocarpus sericoarpus (Moraceae, Alstonia scholaris (Apocynaceae, Knema cinerea (Myristicaceae, Litsea mappacea (Lauraceae, and Palaquium obovatum (Sapotaceae. The nests were found in 0-11 meters (11 nests, 11-20 meters (40 nests, and more than 21 meters (51 nests from ground level. The nests of giant honey bee were found in sturdy and woody branches, hard to peel, the slope of the branches was <60°, and nests were protected by liane plants, foliage, or both them.
15. Nest observations of the long-eared owl (Asio otus) in Benton County, Oregon, with notes on their food habits
Science.gov (United States)
Richard T. Reynolds
1970-01-01
A nesting pair of long-eared owls was found 10 miles north of Corvallis, Benton County, Oregon, on 24 April, 1969. The pair was observed and photographed until 30 May, when the young left the nest. This is the third record of nesting Asio otus west of the Oregon Cascades. Gabrielson and Jewett (1940) reported that Pope collected eggs from a nest...
16. Birds' nesting parameters in four forest types in the Pantanal wetland.
Science.gov (United States)
Pinho, J B; Marini, M A
2014-11-01
We tested the heterogeneity/productivity hypothesis with respect to the abundance and richness of birds and the vegetation density hypothesis with respect to birds' nest predation rates, and determined the relative importance of forested vegetation formations for the conservation of birds in the Pantanal. We estimated the apparent nesting success, and the abundance and richness of nesting birds' in four forest types, by monitoring nests during two reproductive seasons in four forested physiognomies (two high productivity/heterogeneity evergreen forests = Cambará and Landi; two low productivity/heterogeneity dry forests = Cordilheira and Carvoeiro) in the Pantanal wetland in Poconé, State of Mato Grosso, Brazil. We found 381 nests of 46 species (35 Passeriformes and 11 non-Passeriformes) in the four forest types. Of these, we monitored 220 active nests belonging to 44 species, 101 during the reproductive season of 2001 and 119 in 2002. We supported the productivity/heterogeneity hypothesis since the two evergreen forests had higher nest abundance and one of them (Cambará) had higher nesting species richness than the dry forests. The number of nests found in each habitat differed with most nests monitored in the Cambará forest (82%), followed by Landi (9%), Cordilheira (6%) and Carvoeiro (3%) forests. The total number of nests monitored was significantly higher in evergreen forests than in dry forests. Also, more species nested in evergreen (37 species) than in dry (16 species) forests. A Correspondence Analysis revealed that only Carvoeiros had a different nesting bird community. The overall apparent nesting success of 220 nests was 26.8%. We did not support the vegetation density hypothesis since nest predation rates were similar between evergreen (73.5%) and dry (70%) forests, and were higher in the Landi (85%) than in the other three forests (69.2 to 72.2%). Our data indicate that Cambará forests seem to be a key nesting habitat for many bird species of the
17. Lesser prairie-chicken nest site selection, microclimate, and nest survival in association with vegetation response to a grassland restoration program
Science.gov (United States)
Boal, Clint W.; Grisham, Blake A.; Haukos, David A.; Zavaleta, Jennifer C.; Dixon, Charles
2014-01-01
Climate models predict that the region of the Great Plains Landscape Conservation Cooperative (GPLCC) will experience increased maximum and minimum temperatures, reduced frequency but greater intensity of precipitation events, and earlier springs. These climate changes along with different landscape management techniques may influence the persistence of the lesser prairie-chicken (Tympanuchus pallidicinctus), a candidate for protection under the Endangered Species Act and a priority species under the GPLCC, in positive or negative ways. The objectives of this study were to conduct (1) a literature review of lesser prairie-chicken nesting phenology and ecology, (2) an analysis of thermal aspects of lesser prairie-chicken nest microclimate data, and (3) an analysis of nest site selection, nest survival, and vegetation response to 10 years of tebuthiuron and/or grazing treatments. We found few reports in the literature containing useful data on the nesting phenology of lesser prairie-chickens; therefore, managers must rely on short-term observations and measurements of parameters that provide some predictive insight into climate impacts on nesting ecology. Our field studies showed that prairie-chickens on nests were able to maintain relatively consistent average nest temperature of 31 °C and nest humidities of 56.8 percent whereas average external temperatures (20.3–35.0 °C) and humidities (35.2–74.9 percent) varied widely throughout the 24 hour (hr) cycle. Grazing and herbicide treatments within our experimental areas were designed to be less intensive than in common practice. We determined nest locations by radio-tagging hen lesser prairie-chickens captured at leks, which are display grounds at which male lesser prairie-chickens aggregate and attempt to attract a female for mating. Because nest locations selected by hen lesser prairie-chicken are strongly associated with the lek at which they were captured, we assessed nesting habitat use on the basis of hens
18. Nested quantization index modulation for reversible watermarking and its application to healthcare information management systems.
Science.gov (United States)
Ko, Lu-Ting; Chen, Jwu-E; Shieh, Yaw-Shih; Hsin, Hsi-Chin; Sung, Tze-Yun
2012-01-01
Digital watermarking has attracted lots of researches to healthcare information management systems for access control, patients' data protection, and information retrieval. The well-known quantization index modulation-(QIM-) based watermarking has its limitations as the host image will be destroyed; however, the recovery of medical images is essential to avoid misdiagnosis. In this paper, we propose the nested QIM-based watermarking, which is preferable to the QIM-based watermarking for the medical image applications. As the host image can be exactly reconstructed by the nested QIM-based watermarking. The capacity of the embedded watermark can be increased by taking advantage of the proposed nest structure. The algorithm and mathematical model of the nested QIM-based watermarking including forward and inverse model is presented. Due to algorithms and architectures of forward and inverse nested QIM, the concurrent programs and special processors for the nested QIM-based watermarking are easily implemented.
19. Nesting fidelity and molecular evidence for natal homing in the freshwater turtle, Graptemys kohnii.
Science.gov (United States)
Freedberg, Steven; Ewert, Michael A; Ridenhour, Benjamin J; Neiman, Maurine; Nelson, Craig E
2005-07-07
Numerous studies of sea turtle nesting ecology have revealed that females exhibit natal homing, whereby they imprint on the nesting area from which they hatch and subsequently return there to nest as adults. Because freshwater turtles comprise the majority of reptiles known to display environmental sex determination (ESD), the study of natal homing in this group may shed light on recent evolutionary models of sex allocation that are predicated on natal homing in reptiles with ESD. We examined natal homing in Graptemys kohnii, a freshwater turtle with ESD, using mitochondrial sequencing, microsatellite genotyping and mark and recapture of 290 nesting females. Females showed high fidelity to nesting areas, even after being transplanted several kilometres away. A Mantel test revealed significant genetic isolation by distance with respect to nesting locations (r=0.147; psex ratios.
20. Tupinambis merianae as nest predators of crocodilians and turtles in Florida, USA
Science.gov (United States)
Mazzotti, Frank J.; McEachern, Michelle A.; Rochford, Michael; Reed, Robert; Ketterlin Eckles, Jennifer; Vinci, Joy; Edwards, Jake; Wasilewki, Joseph
2015-01-01
Tupinambis merianae, is a large, omnivorous tegu lizard native to South America. Two populations of tegus are established in the state of Florida, USA, but impacts to native species are poorly documented. During summer 2013, we placed automated cameras overlooking one American alligator (Alligator mississippiensis) nest, which also contained a clutch of Florida red-bellied cooter (Pseudemys nelsoni) eggs, and one American crocodile (Crocodylus acutus) nest at a site in southeastern Florida where tegus are established. We documented tegu activity and predation on alligator and turtle eggs at the alligator nest, and tegu activity at the crocodile nest. Our finding that one of the first two crocodilian nests to be monitored was depredated by tegus suggests that tegus should be further evaluated as a threat to nesting reptiles in Florida.
1. Encroachment of Human Activity on Sea Turtle Nesting Sites
Science.gov (United States)
Ziskin, D.; Aubrecht, C.; Elvidge, C.; Tuttle, B.; Baugh, K.; Ghosh, T.
2008-12-01
The encroachment of anthropogenic lighting on sea turtle nesting sites poses a serious threat to the survival of these animals [Nicholas, 2001]. This danger is quantified by combining two established data sets. The first is the Nighttime Lights data produced by the NOAA National Geophysical Data Center [Elvidge et al., 1997]. The second is the Marine Turtle Database produced by the World Conservation Monitoring Centre (WCMC). The technique used to quantify the threat of encroachment is an adaptation of the method described in Aubrecht et al. [2008], which analyzes the stress on coral reef systems by proximity to nighttime lights near the shore. Nighttime lights near beaches have both a direct impact on turtle reproductive success since they disorient hatchlings when they mistake land-based lights for the sky-lit surf [Lorne and Salmon, 2007] and the lights are also a proxy for other anthropogenic threats. The identification of turtle nesting sites with high rates of encroachment will hopefully steer conservation efforts to mitigate their effects [Witherington, 1999]. Aubrecht, C, CD Elvidge, T Longcore, C Rich, J Safran, A Strong, M Eakin, KE Baugh, BT Tuttle, AT Howard, EH Erwin, 2008, A global inventory of coral reef stressors based on satellite observed nighttime lights, Geocarto International, London, England: Taylor and Francis. In press. Elvidge, CD, KE Baugh, EA Kihn, HW Kroehl, ER Davis, 1997, Mapping City Lights with Nighttime Data from the DMSP Operational Linescan System, Photogrammatic Engineering and Remote Sensing, 63:6, pp. 727-734. Lorne, JK, M Salmon, 2007, Effects of exposure to artificial lighting on orientation of hatchling sea turtles on the beach and in the ocean, Endangered Species Research, Vol. 3: 23-30. Nicholas, M, 2001, Light Pollution and Marine Turtle Hatchlings: The Straw that Breaks the Camel's Back?, George Wright Forum, 18:4, p77-82. Witherington, BE, 1999, Reducing Threats To Nesting Habitat, Research and Management Techniques for
2. Nest survival is influenced by parental behaviour and heterospecifics in a mixed-species colony
Science.gov (United States)
Brussee, Brianne E.; Coates, Peter S.; Hothem, Roger L.; Howe, Kristy; Casazza, Michael L.; Eadie, John M.
2016-01-01
Studies of avian nest success often focus on examining influences of variation in environmental and seasonal factors. However, in-depth evaluations can also incorporate variation in individual incubation behaviour to further advance our understanding of avian reproductive ecology. We examined these relationships in colonially nesting Black-crowned Night-Herons Nycticorax nycticorax using intensive video-monitoring methods to quantify incubation behaviours. We modelled nest survival as a function of both extrinsic factors and incubation behaviours over a 3-year period (2010–12) on Alcatraz Island, USA. Model-averaged parameter estimates indicated that nest survival increased as a function of greater incubation constancy (% of time spent incubating eggs within a 24-h period), and average daily precipitation throughout the nesting stage. Common Ravens Corvus corax are the only known nest predator of Night-Herons on Alcatraz Island, as on many other coastal Pacific islands. We also investigated the effects of heterospecific nesting of California Gulls Larus californicus and Western Gulls Larus occidentalis in a mixed-species colony with Night-Herons, based on nesting proximity data collected over a 2-year period (2011–12). This second analysis indicated that, in addition to incubation behaviours, nesting heterospecifics are an important factor for explaining variation in Night-Heron nest survival. However, contrary to our original expectation, we found that Night-Herons experienced increased nest survival with increasing distance from gull colony boundaries. These results may apply to other areas with multiple colonial nesting species and similar predator communities and climatic patterns.
3. Hatching success of Caspian terns nesting in the lower Laguna Madre, Texas, USA
Science.gov (United States)
Mitchell, C.A.; Custer, T.W.
1986-01-01
The average clutch size of Caspian Terns nesting in a colony in the Lower Laguna Madre near Laguna Vista, Texas, USA in 1984 was 1.9 eggs per nest. Using the Mayfield method for calculating success, one egg hatched in 84.1% of the nests and 69.8% of the eggs laid hatched. These hatching estimates are as high or higher than estimates from colonies in other areas.
4. Comparison of the prelaying behavior of nest layers and litter layers.
Science.gov (United States)
Zupan, M; Kruschwitz, A; Buchwalder, T; Huber-Eicher, B; Stuhec, I
2008-03-01
The Swiss Animal Welfare Act decrees that the housing conditions of farm animals must guarantee animal welfare. In the process of developing a method to test nest boxes for their suitability for laying hens, we conducted an investigation using preference testing. It was aimed at verifying the occurrence of different types of layers within the same laying strain and to investigate the choice of a nest site. At the onset of lay, 24 individually housed hens were given the choice of 2 nest sites: a nest box or a litter tray. The chosen nest site and the behavior of the hen, 1 h prior to oviposition, were recorded at 3 stages during the period in which the first 20 eggs were laid. The majority (17) of the hens laid consistently in the nest box, and 7 hens laid consistently in the litter tray. Litter layers spent more time exploring during the hour prior to oviposition than did nest layers, and their final nest visit (when an egg was laid) was shorter. There was no significant difference in the number of entries into the chosen nest site between layers of the 2 types. As expected, the level of restlessness of hens decreased with laying experience. In the hour prior to oviposition, the frequency of foraging and resting increased, whereas the frequency of exploring and nest seeking decreased, and the number of nest-site visits declined. We conclude that there may be at least 2 different types of laying hens that show different nest-site preferences, with concomitantly different prelaying behavior.
5. Nesting fidelity and molecular evidence for natal homing in the freshwater turtle, Graptemys kohnii
OpenAIRE
Freedberg, Steven; Ewert, Michael A; Ridenhour, Benjamin J.; Neiman, Maurine; Nelson, Craig E
2005-01-01
Numerous studies of sea turtle nesting ecology have revealed that females exhibit natal homing, whereby they imprint on the nesting area from which they hatch and subsequently return there to nest as adults. Because freshwater turtles comprise the majority of reptiles known to display environmental sex determination (ESD), the study of natal homing in this group may shed light on recent evolutionary models of sex allocation that are predicated on natal homing in reptiles with ESD. We examined...
6. Raccoon removal reduces sea turtle nest depredation in the Ten Thousand Islands of Florida
Science.gov (United States)
Garmestani, A.S.; Percival, H.F.
2005-01-01
Predation by raccoons, Procyon lotor marinus (L.), is the primary cause of sea turtle nest loss in the Ten Thousand Islands archipelago. Four islands within Ten Thousand Islands National Wildlife Refuge were surveyed for sea turtle nesting activity from 1991-95. Raccoons depredated 76-100% of nests on Panther Key from 1991-94, until 14 raccoons were removed in 1995 resulting in 0% depredation and 2 more were removed in 1996 resulting in 0% depredation. Raccoon removal may be an effective management option for increasing sea turtle nest survival on barrier islands.
7. Anti-predator meshing may provide greater protection for sea turtle nests than predator removal.
Science.gov (United States)
O'Connor, Julie M; Limpus, Colin J; Hofmeister, Kate M; Allen, Benjamin L; Burnett, Scott E
2017-01-01
The problem of how to protect sea turtle nests from terrestrial predators is of worldwide concern. On Queensland's southern Sunshine Coast, depredation of turtle nests by the introduced European red fox (Vulpes vulpes) has been recorded as the primary terrestrial cause of egg and hatchling mortality. We investigated the impact of foxes on the nests of the loggerhead turtle (Caretta caretta) and occasional green turtle (Chelonia mydas) over ten nesting seasons. Meshing of nests with fox exclusion devices (FEDs) was undertaken in all years accompanied by lethal fox control in the first five-year period, but not in the second five-year period. Lethal fox control was undertaken in the study area from 2005 to February 2010, but foxes still breached 27% (range19-52%) of turtle nests. In the second five-year period, despite the absence of lethal fox control, the average percentage of nests breached was less than 3% (range 0-4%). Comparison of clutch depredation rates in the two five-year periods demonstrated that continuous nest meshing may be more effective than lethal fox control in mitigating the impact of foxes on turtle nests. In the absence of unlimited resources available for the eradication of exotic predators, the use of FEDs and the support and resourcing of a dedicated volunteer base can be considered an effective turtle conservation tool on some beaches.
8. Anti-predator meshing may provide greater protection for sea turtle nests than predator removal
Science.gov (United States)
O’Connor, Julie M.; Limpus, Colin J.; Hofmeister, Kate M.; Allen, Benjamin L.; Burnett, Scott E.
2017-01-01
The problem of how to protect sea turtle nests from terrestrial predators is of worldwide concern. On Queensland’s southern Sunshine Coast, depredation of turtle nests by the introduced European red fox (Vulpes vulpes) has been recorded as the primary terrestrial cause of egg and hatchling mortality. We investigated the impact of foxes on the nests of the loggerhead turtle (Caretta caretta) and occasional green turtle (Chelonia mydas) over ten nesting seasons. Meshing of nests with fox exclusion devices (FEDs) was undertaken in all years accompanied by lethal fox control in the first five-year period, but not in the second five-year period. Lethal fox control was undertaken in the study area from 2005 to February 2010, but foxes still breached 27% (range19–52%) of turtle nests. In the second five-year period, despite the absence of lethal fox control, the average percentage of nests breached was less than 3% (range 0–4%). Comparison of clutch depredation rates in the two five-year periods demonstrated that continuous nest meshing may be more effective than lethal fox control in mitigating the impact of foxes on turtle nests. In the absence of unlimited resources available for the eradication of exotic predators, the use of FEDs and the support and resourcing of a dedicated volunteer base can be considered an effective turtle conservation tool on some beaches. PMID:28187181
9. Management and protection protocols for nesting sea turtles on Cape Hatteras National Seashore, North Carolina
Science.gov (United States)
Cohen, J.B.
2005-01-01
Executive Summary 1. The southeast U.S. population of the loggerhead turtle (Caretta caretta) has increased since the species was listed as federally threatened in 1978. Since standardized monitoring began in North Carolina in 1995, the number of nests at Cape Hatteras National Seashore (CAHA) fluctuated from year to year, and was lowest in 1996 and 1997 (39 nests) and highest in 2003 (101 nests). Green turtles (Chelonia mydas) and leatherback turtles (Dermochelys coriacea) have nested in small numbers at CAHA, sporadically over time. 2. Hatching success of sea turtle nests typically approaches 80%. At CAHA hatching success from 1999-2003 was low when hurricanes hit during the nesting season (30%-38%), and ranged from 52%-70% otherwise. Hatching success at CAHA is usually correlated with hatching success in the surrounding subpopulation (north Florida to North Carolina). 3. Inclement weather, predation, and human recreation can negatively impact nesting rate and hatching success. 4. Currently there is little protection from recreation at CAHA for nesting females and nests that have not been found by monitors. We propose three management options to provide such protection, and to increase protection for known nests and hatchlings. We propose an adaptive management framework for assessing the effectiveness of these management options in improving sea turtle nesting rate and nest and hatchling survival. 5. We recommend continued efforts to trap and remove mammalian predators from all sea turtle habitat. We further recommend intensive monitoring and surveillance of protected areas to determine the extent and timing of threats to nests and broods, including nest overwash, predation, and disturbance or vandalism by humans. 6. Continue to relocate nests and assist stranded turtles according to North Carolina Wildlife Resources Commission guidelines. 7. Artificial light sources pose a serious threat to sea turtles in some parts of CAHA, which must be remedied immediately
10. Electron scale nested quadrupole Hall field in Cluster observations of magnetic reconnection
CERN Document Server
Jain, Neeraj
2014-01-01
This Letter presents the first evidence of a new and unique feature of spontaneous reconnection at multiple sites in electron current sheet, viz. nested quadrupole structure of Hall field at electron scales, in Cluster observations. The new nested quadrupole is a consequence of electron scale processes in reconnection. Whistler response of the upstream plasma to the interaction of electron flows from neighboring reconnection sites produces a large scale quadrupole Hall field enclosing the quadrupole fields of the multiple sites, thus forming a nested structure. Electron-magnetohydrodynamic simulations of an electron current sheet yields mechanism of the formation of nested quadrupole.
11. Identifying Kittlitz's Murrelet nesting habitat in North America at the landscape scale
Science.gov (United States)
Felis, Jonathan J.; Kissling, Michelle L.; Kaler, Robb S.A.; Kenney, Leah A.; Lawonn, Matthew J.
2016-01-01
The Kittlitz's Murrelet (Brachyramphus brevirostris) is a small, non-colonial seabird endemic to marine waters of Alaska and eastern Russia that may have experienced significant population decline in recent decades, in part because of low reproductive success and terrestrial threats. Although recent studies have shed new light on Kittlitz's Murrelet nesting habitat in a few discrete areas, the location and extent of suitable nesting habitat throughout most of its range remains unclear. Here, we have compiled all existing nest records and locations to identify landscape-scale parameters (distance to coast, elevation, slope, and land cover) that provide potential nesting habitat in four regions: northern Alaska, Aleutian Islands, Alaska Peninsula Mountains and Kodiak Island, and Pacific Coastal Mountains (including nearshore interior Canada). We produced a final map classifying 12% (70,411 km2) of the lands assessed as potential Kittlitz's Murrelet nesting habitat, with dense but distinct patches in northern Alaska and a more uninterrupted, narrow band extending across the Pacific Coastal Mountains, Alaska Peninsula Mountains, and Aleutian Islands. The extent of habitat-capable parameter values varied regionally, indicating that the Kittlitz's Murrelet may be able to use a variety of habitats for nesting, depending on availability. Future nesting habitat studies could employ spatially random sampling designs to allow for quantitatively robust modeling of nesting habitat and predictive extrapolation to areas where nests have not been located but likely exist.
12. Greater sage-grouse nest predators in the Virginia Mountains of northwestern Nevada
Science.gov (United States)
Lockyer, Zachary B.; Coates, Peter S.; Casazza, Michael L.; Espinosa, Shawn; Delehanty, David J.
2013-01-01
Greater sage-grouse Centrocercus urophasianus, hereafter sage-grouse, populations have declined across their range due to the loss, degradation, and fragmentation of habitat. Habitat alterations can lead not only to vegetative changes but also to shifts in animal behavior and predator composition that may influence population vital rates, such as nest success. For example, common ravens Corvus corax are sage-grouse nest predators, and common raven abundance is positively associated with human-caused habitat alterations. Because nest success is a central component to sage-grouse population persistence, research that identifies factors influencing nest success will better inform conservation efforts. We used videography to unequivocally identify sage-grouse nest predators within the Virginia Mountains of northwestern Nevada, USA, from 2009 to 2011 and used maximum likelihood to calculate daily probability of nest survival. In the Virginia Mountains, fires, energy exploration, and other anthropogenic activities have altered historic sage-grouse habitat. We monitored 71 sage-grouse nests during the study, placing video cameras at 39 nests. Cumulative nest survival for all nests was 22.4% (95% CI, 13.0–33.4%), a survival rate that was significantly lower than other published results for sage-grouse in the Great Basin. Depredation was the primary cause for nest failure in our study (82.5%), and common ravens were the most frequent sage-grouse nest predator, accounting for 46.7% of nest depredations. We also successfully documented a suite of mammalian and reptilian species depredating sage-grouse nests, including some predators never previously confirmed in the literature to be sage-grouse nest predators (i.e., bobcats Lynx rufus and long-tailed weasels Mephitis frenata). Within the high elevation, disturbed habitat of the Virginia Mountains, low sage-grouse nest success may be limiting sage-grouse population growth. These results suggest that management actions that
13. Land cover associations of nesting territories of three sympatric buteos in shortgrass prairie
Science.gov (United States)
McConnell, S.; O'Connell, T. J.; Leslie, David M.
2008-01-01
Three species of Buteo hawks nest sympatrically in the southern Great Plains of the United States. Dietary overlap among them is broad and we tested the hypothesis these species partition their breeding habitat spatially. We compared land cover and topography around 224 nests of the three species breeding in shortgrass prairie in 2004 and 2005. Red-tailed Hawks (Buteo jamaicensis) nested almost exclusively in riparian timber surrounded by prairie (95% prairie land cover around nests) and disproportionately used areas with greater topographic relief within prairie landscapes. Swainson's Hawks (B. swainsoni) commonly nested in low-relief areas dominated by small-grain production agriculture but generally used habitats in proportion to availability. Most nest sites of Ferruginous Hawks (B. regalis) were in prairie (78% prairie land cover around nests), but some were in areas that were at least partially agricultural. Ferruginous Hawks had at least two times more sand sagebrush (Artemisia filifolia) around their nests than their two congeners. We conclude that sympatric breeding Buteos on the southern Great Plains spatially partitioned nest sites according to subtle differences in land cover and topography.
14. Nesting habits of Centris (Hemisiella) dichrootricha (Hymenoptera: Apidae) in the Northern Cerrado of Brazil
OpenAIRE
Carvalho, Gracy C. A.; Carreira, Léa M. M.; Rêgo, Márcia M. C.; Patrícia M. C. Albuquerque
2016-01-01
The Neotropical bee Centris (Hemisiella) dichrootricha is a solitary bee that nests in pre-existing cavities that occur in the rain forest. This study describes the nesting biology of C. dichrootricha and its preference for nesting in Cerrado and gallery forest habitats. The study was conducted from January 2012 and December 2013, in Mirador State Park in the municipality of Formosa da Serra Negra, Maranhão State, Brazil. For this, wooden trap-nests of 6, 8, 10, 12, 14 and 16 mm in diameter w...
15. Nesting Ecology of Hawksbill Sea Turtles (Eretmochelys imbricata) on Utila, Honduras
Science.gov (United States)
Damazo, Lindsey Renee Eggers
The hawksbill sea turtle (Eretmochelys imbricata) has a circumtropical distribution and plays an important role in maintaining the health of coral reefs. Unfortunately, hawksbill populations have been decimated, and estimated numbers in the Caribbean are less than 10% of populations a century ago. The hawksbill is considered Critically Endangered, and researchers are coordinating worldwide efforts to protect this species. One country where we lack knowledge regarding hawksbills is Honduras. This study aimed to increase our understanding of hawksbill nesting ecology in Caribbean Honduras. Characteristics of hawksbill nesting activity and a nesting beach on the island of Utila were elucidated using satellite telemetry, beach profiling, vegetation surveys, beach monitoring, and nest temperature profiles. We affixed satellite transmitters to two nesting hawksbills, and found the turtles migrated to different countries. One turtle traveled 403 km to a bay in Mexico, and the other traveled 181 km to a Marine Protected Area off Belize. This study presents the first description of hawksbill migration routes from Honduras, facilitating protection efforts for turtles that traverse international waters. To investigate nesting beach and turtle characteristics, we conducted beach monitoring during the 2012 nesting season. Nesting turtle carapace sizes were similar to worldwide values, but hatchlings were heavier. To measure nest temperatures, we placed thermocouple data loggers in four nests and four pseudo-nests. Data suggested metabolic heating may be maintaining nest temperatures above the pivotal temperature. However, large temperature fluctuations corresponding to rainfall from Hurricane Ernesto (as determined using a time series cross-correlation analysis) make it difficult to predict sex ratios, and underscore the impact stochastic events can have on nest temperatures. We created topographic and substrate profiles of the beach, and found it was 475 m long, yet hawksbills
16. Nest box use and productivity of great crested flycatchers in prescribed-burned longleaf pine forests
Science.gov (United States)
White, D.H.; Seginak, J.T.
2000-01-01
Managing for the endangered Red-cockaded Woodpecker (Picoides borealis) on federal lands requires burning large tracts of mature pine forests every 3-5 yr. Many cavity trees that serve as potential nest sites for primary and secondary hole-nesting birds are destroyed by fire. We assessed the efficacy of a nest box program for the Great Crested Flycatcher (Myiarchus crinitus) at Carolina Sandhills National Wildlife Refuge, an area intensively managed for Red-cockaded Woodpeckers. During 1996-1998, we installed and monitored 330 (30 in each of 11 sites) nest boxes in mature (>60 yr) longleaf pine (Pinus palustris) tracts that were burned either in April-June (warm season) or December-March (cool season). Prescribed-burned sites were nearly devoid of snags; we estimated only 0.8/ ha in cool-season burns and 1.7/ha in warm-season burns. Great Crested Flycatchers built nests in 20% of the boxes available to them. Clutch sizes were larger in warm-season burns than in cool-season burns, but fledging success (fledglings/nest hatching -1 egg) was lower. Twenty-two of 59 Great Crested Flycatcher nests were depredated and the proportions in each burn class were similar. We recommend the installation of nest boxes for Great Crested Flycatchers in prescribed-burned pine forests, but additional research is needed in these habitats on nest depredation rates and causes.
17. Nest-site selection pattern of Grusjaponensis in Zhalong Nature Reserve of northeast China
Institute of Scientific and Technical Information of China (English)
WU Qing-ming; ZOU Hong-fei
2011-01-01
Nest-site selection patterns of Red-crowned cranes (Grus japonensis) and the effects of environmental variables were studied during the years of 2002-2008 in Zhalong Nature Reserve, Qiqihar city,northeast China. The nest-site selection pattern of Red-crowned cranes included two orders and three choices: the choice of nest-site habitat type within the macro-habitat order, nest zone selection and nest-site micro-habitat selection within the micro-habitat order. Various habitats (such as Carex swamps and reed fire districts) can be selected as the nest sites for Red-crowned cranes, of which reed swamps (93.15％) are given a preference. Factor Analysis reveals that the micro-habitat selection are affected by four main factors: fire, security (concealment / disturbance),incubation (conditions, nest-material), and food. Further analysis reveals that Red-crowned cranes have certain adaptability to the changes of nesting habitat quality in the Zhalong wetlands. In conclusion, fire, reeds,and water were the most important variables for nest-site habitat selection of Red-crowned Cranes in Zhalong Nature Reserve.
18. Microhabitat characteristics of Lapland Longspur, Calcarius lapponicus, nests at Cape Churchill, Manitoba
Science.gov (United States)
Boal, C.W.; Andersen, D.E.
2005-01-01
We examined microsite characteristics at 21 Lapland Longspur (Calcarius lapponicus) nests and land cover types in which they occurred in Wapusk National Park, Cape Churchill, Manitoba. Nests were located in four of six physiographic-vegetation land-cover types. Regardless of land-cover type, all but one nest was built on a pressure ridge or mound. Nests were built midway between the bottom and top of ridges or mounds with steeper slopes than was randomly available. Longspur nests had a distinctive southwest orientation (P < 0.001). Longspurs selected nest sites that consisted of comparatively greater amounts of shrub species and lesser amounts of moss than were randomly available. Nests were generally well concealed by vegetation (mean = 67.0%) and concealment was negatively associated with amount of graminoid species at the nest (P = 0.0005). Our nesting habitat data may facilitate a better understanding of breeding Lapland Longspur habitat requirements, and potential impacts of habitat degradation by increasing Snow Goose (Chen caerulescens) populations in the study area.
19. Long-term lesser prairie-chicken nest ecology in response to grassland management
Science.gov (United States)
Fritts, Sarah R.; Grisham, Blake A.; Haukos, David A.; Boal, Clint W.; Patten, Michael; Wolfe, Don H.; Dixon, Charles; Cox, Robert D.; Heck, Willard R.
2016-01-01
Long-term population and range declines from habitat loss and fragmentation caused the lesser prairie-chicken (Tympanuchus pallidicinctus) to be a species of concern throughout its range. Current lesser prairie-chicken range in New Mexico and Texas is partially restricted to sand shinnery oak (Quercus havardii; hereafter shinnery oak) prairies, on which cattle grazing is the main socioeconomic driver for private landowners. Cattle producers within shinnery oak prairies often focus land management on shrub eradication using the herbicide tebuthiuron to promote grass production for forage; however, herbicide application alone, and in combination with grazing, may affect nest site selection and nest survival of lesser prairie-chickens through the reduction of shinnery oak and native grasses. We used a controlled, paired, completely randomized design study to assess the influence of grazing and tebuthiuron application and their combined use on nest site selection and nest survival from 2001 to 2010 in Roosevelt County, New Mexico, USA at 2 spatial scales (i.e., treatment and microhabitat) in 4 treatments: tebuthiuron with grazing, tebuthiuron without grazing, no tebuthiuron with grazing, and a control of no tebuthiuron and no grazing. Grazing treatment was a short-duration system in which plots were grazed once during the dormant season and once during the growing season. Stocking rate was calculated each season based on measured forage production and applied to remove ≤25% of available herbaceous material per season. At the treatment scale, we compared nest site selection among treatments using 1-way χ2 tests and nest survival among treatments using a priori candidate nest survival models in Program MARK. At the microhabitat scale, we identified important habitat predictors of nest site selection and nest survival using logistic regression and a priori candidate nest survival models in Program MARK, respectively. Females typically used treatments as expected and
20. Nesting biology of three grassland passerines in the northern tallgrass prairie
Science.gov (United States)
Winter, M.; Johnson, D.H.; Shaffer, J.A.; Svedarsky, W.D.
2004-01-01
Basic nesting information on grassland passerines is needed for improving grassland bird management. Among the information needs are (1) the suitability of nesting habitat, (2) periods during the breeding season in which birds are most vulnerable to disturbances, and (3) how to fit grasslands into a prioritization scheme for conservation. Comparisons of nesting parameters among grassland species will help identify important management considerations. We describe and compare nest-site characteristics, nesting phenology, clutch size, hatching and fledging success, and brood parasitism by Brown-headed Cowbirds (Molothrus ater) for three grassland passerine species nesting in tallgrass prairie of northwestern Minnesota and southeastern North Dakota. During 1998-2002, we found 793 Clay-colored Sparrow (Spizella pallida), 687 Savannah Sparrow (Passerculus sandwichensis), and 315 Bobolink (Dolichonyx oryzivorus) nests. These species differed in many aspects of their breeding ecology. Clay-colored and Savannah sparrows initiated their nests almost 2 weeks earlier than Bobolinks, with peak nesting occurring in June. Clutch size was lower (3.77 ?? 0.03 SE) for Clay-colored Sparrows than Savannah Sparrows (4.13 ?? 0.05) and Bobolinks (5.25 ?? 0.08). The number of host eggs hatched per nest was higher in Bobolinks (3.46 ?? 0.20) than in Clay-colored Sparrows (2.52 ?? 0.09) and Savannah Sparrows (2.41 ?? 0.11), but the number of young fledged per Bobolink nest (1.97) was similar to that of Savannah Sparrows (2.01). Clay-colored Sparrows fledged only 1.35 host young per nest. Mayfield nest success was higher for Savannah Sparrows (31.4%) than for Clay-colored Sparrows (27.4%) or Bobolinks (20.7%). The main cause of nest failure was nest predation: predation in Clay-colored Sparrows (47.9%) was higher than in Savannah Sparrows (33.5%) but similar to Bobolinks (41.8%). Brood parasitism was lower in Clay-colored Sparrows (5.1%) than in Bobolinks (10.8%), and intermediate (6.7%) in
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http://exploreuk.uky.edu/catalog/xt7x0k26bk54_7/text
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# ExploreUK
Collections:
0-9 | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
# Image 7 of Kentucky Alumnus, 1988, no. 1
## Part of Kentucky alumnus
¤ IIIIIIIIIIIIII C IIIIIIII|'II. E -r,_rrf III"|"'||•.," I- L CMG fr V _ i IIIIIIIIIIIIIIIII E III'.I|II|.' N - ` I I I I I I I I I I I C y IIIIIII|'·I' u W i (Y • Cgnief on Aging : Sandefs-Brown IIIIII\\\\\\I\\\IIIIlIIIIIIII\\\\\\\\\I\\\\I\\\\\\\\I\I\I\III\IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII\\\\\\\\\\\\I [ There’ s a "we\\-kept’ ’ secret on the UK campus, according to Dr. \Ni\\iam V . = Nfarkesbery , and that is the Center on Aging. The Center, which _ _ l V V — . V Nfarkesbery directs, is a designated program of exceiience on V ‘ V I V CV V both the federai and state ieveis. V .,-VV VV , V‘ (V Qg V . wk V Vi I · V Research efforts aimed primariiy at finding the »»·__·;_f i V` ` [xi? \ _ li ‘ `,. _ _. _ ' gl {Y . — cause of A\zheimer’ s disease has earned the . . e I _ 4_·· ;*? ‘ V , .5. ; ; _ I ~ Center a nationai reputation. Consequentiy, it fi ` \• , ‘. V =’;’ , fi has been named one of ten federaiiy O I ,2.. ` YV ‘ designated and funded research centers, s ._ VV j, "" V] V" V_ piacing UK in the company ofthe 3 3 g 3} ` { l - . University of Southern Caiifornia, n ` { Q! V V ’i I ` . VT Harvard, johns Hopkins, Duke and ' 9 \_ J i l · ` z 3 V ~ Washington Universities which aiso V _ .. I _g,\ V _V AV Vi Q V I have been named Aizheimer’s disease * · V I — ., ’j», __ V I research centers. _ V V I CV} ‘ - ‘ V I On the state ievei, the Center of V _- _ C — "" V. ’ Exceiience designation identifies the __ V W ‘. ,§_§_ I V K V ` VV Center’ s programs as making FV ·..V:_ 5 V~iV' _ E Q ` . T -_‘ ji; _ V V V. VV _ V — ` I ` distinguished contributions to higher f gyil { V er i V - léij ; 5 . .___ IV _Iy· I education in the state and wiii enabie y -·fzV, . _,· V- ’ _ :· " fV V VV I expansion in research. (continued) · ,V A _.'·· J V! z V , z ,7 { I V. . E n ` V ,·" r ° ¢* J · : · ' . » aaahr V i—.V V BY Kev 5¤¤¤S¤¤ I f if r ft V K s ..j `F ` VV;·f I ` Vi 5 UK
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https://www.eneuro.org/highwire/markup/3668014/expansion?width=1000&height=500&iframe=true&postprocessors=highwire_tables%2Chighwire_reclass%2Chighwire_figures%2Chighwire_math%2Chighwire_inline_linked_media%2Chighwire_embed
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Table 1
Results of the model selection procedure for the computational models
ModelLOOIC Δ LOOICSE( Δ LOOIC)
Order10,598.3
Full10,607.89.630.2
tACS10,608.510.239.4
Null10,615.317.033.2
• All differences in LOOIC are small compared with their SEs and model selection is therefore inconclusive.
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http://www.math.wsu.edu/kcooper/M300/essential/node11.html
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Next: Quotations Up: Essential LATEX Previous: Document Styles and Style
# Environments
We mentioned earlier the idea of identifying a quotation to LATEX so that it could arrange to typeset it correctly. To do this you enclose the quotation between the commands \begin{quotation} and \end{quotation}. This is an example of a LATEX construction called an environment. A number of special effects are obtained by putting text into particular environments.
Subsections
Kevin Cooper 2002-03-01
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http://allcharters.info/finding-the-equation-of-a-line-in-standard-form
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# Finding The Equation Of A Line In Standard Form
## Finding Slope From The Standard Form Of A Linear Equation
Writing The Equation Of A Line In Standard Form Youtube. Solved Write The Equation Of Each Line In Standard Form . Finding Slope From The Standard Form Of A Linear Equation . Straight Lines. How To Find The Equation Of A Tangent Line 8 Steps. How To Find The Equation Of A Tangent Line 8 Steps. Y Y1 Mx X1 Find The Equation Of A Line Using Point Slope Form . Finding Equations Of Lines Given A Parallel Or Perpendicular Line . Standard And Vertex Form Of The Equation Of Parabola And How It . Standard And Vertex Form Of The Equation Of Parabola And How It . How To Find The Equation Of A Tangent Line 8 Steps. Write A Slope Intercept Equation Given An X Y Table Youtube. How To Find A Slope Of A Straight Line With Ax By C 0 Math . Equation Of A Line Passing Through Two Points Worksheets. Finding The Slope And Y Intercept. How To Find The Vertex Of A Quadratic Equation 10 Steps. Finding The Equation Of A Line Given A Point And The Slope Youtube. Linear Equation Of A Line Worksheets. Equation Of A Circle In Standard Form Formula Practice Problems .
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https://terrytao.wordpress.com/2014/11/13/254a-announcement-analytic-prime-number-theory/
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In the winter quarter (starting January 5) I will be teaching a graduate topics course entitled “An introduction to analytic prime number theory“. As the name suggests, this is a course covering many of the analytic number theory techniques used to study the distribution of the prime numbers ${{\mathcal P} = \{2,3,5,7,11,\dots\}}$. I will list the topics I intend to cover in this course below the fold. As with my previous courses, I will place lecture notes online on my blog in advance of the physical lectures.
The type of results about primes that one aspires to prove here is well captured by Landau’s classical list of problems:
1. Even Goldbach conjecture: every even number ${N}$ greater than two is expressible as the sum of two primes.
2. Twin prime conjecture: there are infinitely many pairs ${n,n+2}$ which are simultaneously prime.
3. Legendre’s conjecture: for every natural number ${N}$, there is a prime between ${N^2}$ and ${(N+1)^2}$.
4. There are infinitely many primes of the form ${n^2+1}$.
All four of Landau’s problems remain open, but we have convincing heuristic evidence that they are all true, and in each of the four cases we have some highly non-trivial partial results, some of which will be covered in this course. We also now have some understanding of the barriers we are facing to fully resolving each of these problems, such as the parity problem; this will also be discussed in the course.
One of the main reasons that the prime numbers ${{\mathcal P}}$ are so difficult to deal with rigorously is that they have very little usable algebraic or geometric structure that we know how to exploit; for instance, we do not have any useful prime generating functions. One of course can create non-useful functions of this form, such as the ordered parameterisation ${n \mapsto p_n}$ that maps each natural number ${n}$ to the ${n^{th}}$ prime ${p_n}$, or one could invoke Matiyasevich’s theorem to produce a polynomial of many variables whose only positive values are prime, but these sorts of functions have no usable structure to exploit (for instance, they give no insight into any of the Landau problems listed above; see also Remark 2 below). The various primality tests in the literature, while useful for practical applications (e.g. cryptography) involving primes, have also proven to be of little utility for these sorts of problems; again, see Remark 2. In fact, in order to make plausible heuristic predictions about the primes, it is best to take almost the opposite point of view to the structured viewpoint, using as a starting point the belief that the primes exhibit strong pseudorandomness properties that are largely incompatible with the presence of rigid algebraic or geometric structure. We will discuss such heuristics later in this course.
It may be in the future that some usable structure to the primes (or related objects) will eventually be located (this is for instance one of the motivations in developing a rigorous theory of the “field with one element“, although this theory is far from being fully realised at present). For now, though, analytic and combinatorial methods have proven to be the most effective way forward, as they can often be used even in the near-complete absence of structure.
In this course, we will not discuss combinatorial approaches (such as the deployment of tools from additive combinatorics) in depth, but instead focus on the analytic methods. The basic principles of this approach can be summarised as follows:
1. Rather than try to isolate individual primes ${p}$ in ${{\mathcal P}}$, one works with the set of primes ${{\mathcal P}}$ in aggregate, focusing in particular on asymptotic statistics of this set. For instance, rather than try to find a single pair ${n,n+2}$ of twin primes, one can focus instead on the count ${|\{ n \leq x: n,n+2 \in {\mathcal P} \}|}$ of twin primes up to some threshold ${x}$. Similarly, one can focus on counts such as ${|\{ n \leq N: n, N-n \in {\mathcal P} \}|}$, ${|\{ p \in {\mathcal P}: N^2 < p < (N+1)^2 \}|}$, or ${|\{ n \leq x: n^2 + 1 \in {\mathcal P} \}|}$, which are the natural counts associated to the other three Landau problems. In all four of Landau’s problems, the basic task is now to obtain a non-trivial lower bounds on these counts.
2. If one wishes to proceed analytically rather than combinatorially, one should convert all these counts into sums, using the fundamental identity
$\displaystyle |A| = \sum_n 1_A(n),$
(or variants thereof) for the cardinality ${|A|}$ of subsets ${A}$ of the natural numbers ${{\bf N}}$, where ${1_A}$ is the indicator function of ${A}$ (and ${n}$ ranges over ${{\bf N}}$). Thus we are now interested in estimating (and particularly in lower bounding) sums such as
$\displaystyle \sum_{n \leq N} 1_{{\mathcal P}}(n) 1_{{\mathcal P}}(N-n),$
$\displaystyle \sum_{n \leq x} 1_{{\mathcal P}}(n) 1_{{\mathcal P}}(n+2),$
$\displaystyle \sum_{N^2 < n < (N+1)^2} 1_{{\mathcal P}}(n),$
or
$\displaystyle \sum_{n \leq x} 1_{{\mathcal P}}(n^2+1).$
3. Once one expresses number-theoretic problems in this fashion, we are naturally led to the more general question of how to accurately estimate (or, less ambitiously, to lower bound or upper bound) sums such as
$\displaystyle \sum_n f(n)$
or more generally bilinear or multilinear sums such as
$\displaystyle \sum_n \sum_m f(n,m)$
or
$\displaystyle \sum_{n_1,\dots,n_k} f(n_1,\dots,n_k)$
for various functions ${f}$ of arithmetic interest. (Importantly, one should also generalise to include integrals as well as sums, particularly contour integrals or integrals over the unit circle or real line, but we postpone discussion of these generalisations to later in the course.) Indeed, a huge portion of modern analytic number theory is devoted to precisely this sort of question. In many cases, we can predict an expected main term for such sums, and then the task is to control the error term between the true sum and its expected main term. It is often convenient to normalise the expected main term to be zero or negligible (e.g. by subtracting a suitable constant from ${f}$), so that one is now trying to show that a sum of signed real numbers (or perhaps complex numbers) is small. In other words, the question becomes one of rigorously establishing a significant amount of cancellation in one’s sums (also referred to as a gain or savings over a benchmark “trivial bound”). Or to phrase it negatively, the task is to rigorously prevent a conspiracy of non-cancellation, caused for instance by two factors in the summand ${f(n)}$ exhibiting an unexpectedly large correlation with each other.
4. It is often difficult to discern cancellation (or to prevent conspiracy) directly for a given sum (such as ${\sum_n f(n)}$) of interest. However, analytic number theory has developed a large number of techniques to relate one sum to another, and then the strategy is to keep transforming the sum into more and more analytically tractable expressions, until one arrives at a sum for which cancellation can be directly exhibited. (Note though that there is often a short-term tradeoff between analytic tractability and algebraic simplicity; in a typical analytic number theory argument, the sums will get expanded and decomposed into many quite messy-looking sub-sums, until at some point one applies some crude estimation to replace these messy sub-sums by tractable ones again.) There are many transformations available, ranging such basic tools as the triangle inequality, pointwise domination, or the Cauchy-Schwarz inequality to key identities such as multiplicative number theory identities (such as the Vaughan identity and the Heath-Brown identity), Fourier-analytic identities (e.g. Fourier inversion, Poisson summation, or more advanced trace formulae), or complex analytic identities (e.g. the residue theorem, Perron’s formula, or Jensen’s formula). The sheer range of transformations available can be intimidating at first; there is no shortage of transformations and identities in this subject, and if one applies them randomly then one will typically just transform a difficult sum into an even more difficult and intractable expression. However, one can make progress if one is guided by the strategy of isolating and enhancing a desired cancellation (or conspiracy) to the point where it can be easily established (or dispelled), or alternatively to reach the point where no deep cancellation is needed for the application at hand (or equivalently, that no deep conspiracy can disrupt the application).
5. One particularly powerful technique (albeit one which, ironically, can be highly “ineffective” in a certain technical sense to be discussed later) is to use one potential conspiracy to defeat another, a technique I refer to as the “dueling conspiracies” method. This technique may be unable to prevent a single strong conspiracy, but it can sometimes be used to prevent two or more such conspiracies from occurring, which is particularly useful if conspiracies come in pairs (e.g. through complex conjugation symmetry, or a functional equation). A related (but more “effective”) strategy is to try to “disperse” a single conspiracy into several distinct conspiracies, which can then be used to defeat each other.
As stated before, the above strategy has not been able to establish any of the four Landau problems as stated. However, they can come close to such problems (and we now have some understanding as to why these problems remain out of reach of current methods). For instance, by using these techniques (and a lot of additional effort) one can obtain the following sample partial results in the Landau problems:
1. Chen’s theorem: every sufficiently large even number ${N}$ is expressible as the sum of a prime and an almost prime (the product of at most two primes). The proof proceeds by finding a nontrivial lower bound on ${\sum_{n \leq N} 1_{\mathcal P}(n) 1_{{\mathcal E}_2}(N-n)}$, where ${{\mathcal E}_2}$ is the set of almost primes.
2. Zhang’s theorem: There exist infinitely many pairs ${p_n, p_{n+1}}$ of consecutive primes with ${p_{n+1} - p_n \leq 7 \times 10^7}$. The proof proceeds by giving a non-negative lower bound on the quantity ${\sum_{x \leq n \leq 2x} (\sum_{i=1}^k 1_{\mathcal P}(n+h_i) - 1)}$ for large ${x}$ and certain distinct integers ${h_1,\dots,h_k}$ between ${0}$ and ${7 \times 10^7}$. (The bound ${7 \times 10^7}$ has since been lowered to ${246}$.)
3. The Baker-Harman-Pintz theorem: for sufficiently large ${x}$, there is a prime between ${x}$ and ${x + x^{0.525}}$. Proven by finding a nontrivial lower bound on ${\sum_{x \leq n \leq x+x^{0.525}} 1_{\mathcal P}(n)}$.
4. The Friedlander-Iwaniec theorem: There are infinitely many primes of the form ${n^2+m^4}$. Proven by finding a nontrivial lower bound on ${\sum_{n,m: n^2+m^4 \leq x} 1_{{\mathcal P}}(n^2+m^4)}$.
We will discuss (simpler versions of) several of these results in this course.
Of course, for the above general strategy to have any chance of succeeding, one must at some point use some information about the set ${{\mathcal P}}$ of primes. As stated previously, usefully structured parametric descriptions of ${{\mathcal P}}$ do not appear to be available. However, we do have two other fundamental and useful ways to describe ${{\mathcal P}}$:
1. (Sieve theory description) The primes ${{\mathcal P}}$ consist of those numbers greater than one, that are not divisible by any smaller prime.
2. (Multiplicative number theory description) The primes ${{\mathcal P}}$ are the multiplicative generators of the natural numbers ${{\bf N}}$: every natural number is uniquely factorisable (up to permutation) into the product of primes (the fundamental theorem of arithmetic).
The sieve-theoretic description and its variants lead one to a good understanding of the almost primes, which turn out to be excellent tools for controlling the primes themselves, although there are known limitations as to how much information on the primes one can extract from sieve-theoretic methods alone, which we will discuss later in this course. The multiplicative number theory methods lead one (after some complex or Fourier analysis) to the Riemann zeta function (and other L-functions, particularly the Dirichlet L-functions), with the distribution of zeroes (and poles) of these functions playing a particularly decisive role in the multiplicative methods.
Many of our strongest results in analytic prime number theory are ultimately obtained by incorporating some combination of the above two fundamental descriptions of ${{\mathcal P}}$ (or variants thereof) into the general strategy described above. In contrast, more advanced descriptions of ${{\mathcal P}}$, such as those coming from the various primality tests available, have (until now, at least) been surprisingly ineffective in practice for attacking problems such as Landau’s problems. One reason for this is that such tests generally involve operations such as exponentiation ${a \mapsto a^n}$ or the factorial function ${n \mapsto n!}$, which grow too quickly to be amenable to the analytic techniques discussed above.
To give a simple illustration of these two basic approaches to the primes, let us first give two variants of the usual proof of Euclid’s theorem:
Theorem 1 (Euclid’s theorem) There are infinitely many primes.
Proof: (Multiplicative number theory proof) Suppose for contradiction that there were only finitely many primes ${p_1,\dots,p_n}$. Then, by the fundamental theorem of arithmetic, every natural number is expressible as the product of the primes ${p_1,\dots,p_n}$. But the natural number ${p_1 \dots p_n + 1}$ is larger than one, but not divisible by any of the primes ${p_1,\dots,p_n}$, a contradiction.
(Sieve-theoretic proof) Suppose for contradiction that there were only finitely many primes ${p_1,\dots,p_n}$. Then, by the Chinese remainder theorem, the set of natural numbers ${A}$ that is not divisible by any of the ${p_1,\dots,p_n}$ has density ${\prod_{i=1}^n (1-\frac{1}{p_i})}$, that is to say
$\displaystyle \lim_{N \rightarrow \infty} \frac{1}{N} | A \cap \{1,\dots,N\} | = \prod_{i=1}^n (1-\frac{1}{p_i}).$
In particular, ${A}$ has positive density and thus contains an element larger than ${1}$. But the least such element is one further prime in addition to ${p_1,\dots,p_n}$, a contradiction. $\Box$
Remark 1 One can also phrase the proof of Euclid’s theorem in a fashion that largely avoids the use of contradiction; see this previous blog post for more discussion.
Both proofs in fact extend to give a stronger result:
Theorem 2 (Euler’s theorem) The sum ${\sum_{p \in {\mathcal P}} \frac{1}{p}}$ is divergent.
Proof: (Multiplicative number theory proof) By the fundamental theorem of arithmetic, every natural number is expressible uniquely as the product ${p_1^{a_1} \dots p_n^{a_n}}$ of primes in increasing order. In particular, we have the identity
$\displaystyle \sum_{n=1}^\infty \frac{1}{n} = \prod_{p \in {\mathcal P}} ( 1 + \frac{1}{p} + \frac{1}{p^2} + \dots )$
(both sides make sense in ${[0,+\infty]}$ as everything is unsigned). Since the left-hand side is divergent, the right-hand side is as well. But
$\displaystyle ( 1 + \frac{1}{p} + \frac{1}{p^2} + \dots ) = \exp( \frac{1}{p} + O( \frac{1}{p^2} ) )$
and ${\sum_{p \in {\mathcal P}} \frac{1}{p^2}\leq \sum_{n=1}^\infty \frac{1}{n^2} < \infty}$, so ${\sum_{p \in {\mathcal P}} \frac{1}{p}}$ must be divergent.
(Sieve-theoretic proof) Suppose for contradiction that the sum ${\sum_{p \in {\mathcal P}} \frac{1}{p}}$ is convergent. For each natural number ${k}$, let ${A_k}$ be the set of natural numbers not divisible by the first ${k}$ primes ${p_1,\dots,p_k}$, and let ${A}$ be the set of numbers not divisible by any prime in ${{\mathcal P}}$. As in the previous proof, each ${A_k}$ has density ${\prod_{i=1}^k (1-\frac{1}{p_i})}$. Also, since ${\{1,\dots,N\}}$ contains at most ${\frac{N}{p}}$ multiples of ${p}$, we have from the union bound that
$\displaystyle | A \cap \{1,\dots,N \}| = |A_k \cap \{1,\dots,N\}| - O( N \sum_{i > k} \frac{1}{p_i} ).$
Since ${\sum_{i=1}^\infty \frac{1}{p_i}}$ is assumed to be convergent, we conclude that the density of ${A_k}$ converges to the density of ${A}$; thus ${A}$ has density ${\prod_{i=1}^\infty (1-\frac{1}{p_i})}$, which is non-zero by the hypothesis that ${\sum_{i=1}^\infty \frac{1}{p_i}}$ converges. On the other hand, since the primes are the only numbers greater than one not divisible by smaller primes, ${A}$ is just ${\{1\}}$, which has density zero, giving the desired contradiction. $\Box$
Remark 2 We have seen how easy it is to prove Euler’s theorem by analytic methods. In contrast, there does not seem to be any known proof of this theorem that proceeds by using any sort of prime-generating formula or a primality test, which is further evidence that such tools are not the most effective way to make progress on problems such as Landau’s problems. (But the weaker theorem of Euclid, Theorem 1, can sometimes be proven by such devices.)
The two proofs of Theorem 2 given above are essentially the same proof, as is hinted at by the geometric series identity
$\displaystyle 1 + \frac{1}{p} + \frac{1}{p^2} + \dots = (1 - \frac{1}{p})^{-1}.$
One can also see the Riemann zeta function begin to make an appearance in both proofs. Once one goes beyond Euler’s theorem, though, the sieve-theoretic and multiplicative methods begin to diverge significantly. On one hand, sieve theory can still handle to some extent sets such as twin primes, despite the lack of multiplicative structure (one simply has to sieve out two residue classes per prime, rather than one); on the other, multiplicative number theory can attain results such as the prime number theorem for which purely sieve theoretic techniques have not been able to establish. The deepest results in analytic number theory will typically require a combination of both sieve-theoretic methods and multiplicative methods in conjunction with the many transforms discussed earlier (and, in many cases, additional inputs from other fields of mathematics such as arithmetic geometry, ergodic theory, or additive combinatorics).
— 1. Topics covered —
Analytic prime number theory is a vast subject (the 615-page text of Iwaniec and Kowalski, for instance, gives a good indication as to its scope). I will therefore have to be somewhat selective in deciding what subset of this field to cover. I have chosen the following “core” topics to focus on:
• Elementary multiplicative number theory.
• Heuristic random models for the primes.
• The basic theory of the Riemann zeta function and Dirichlet L-functions, and their relationship with the primes.
• Zero-free regions for the zeta function and the Dirichet L-function, including Siegel’s theorem.
• The prime number theorem, the Siegel-Walfisz theorem, and the Bombieri-Vinogradov theorem.
• Sieve theory, small and large gaps between the primes, and the parity problem.
• Exponential sum estimates over the integers, and the Vinogradov-Korobov zero-free region.
• Zero density estimates, Hohiesel’s theorem, and Linnik’s theorem.
• Exponential sum estimates over finite fields, and improved distribution estimates for the primes.
• (If time permits) Exponential sum estimates over the primes, the circle method, and Vinogradov’s three-primes theorem.
In order to cover all this material, I will focus on more qualitative results, as opposed to the strongest quantitative results, in particular I will not attempt to optimise many of the numerical constants and exponents appearing in various estimates. This also allows me to downplay the role of some key components of the field which are not essential for establishing the core results of this course at such a qualitative level:
• I will minimise the use of algebraic number theory tools (such as the class number formula).
• I will avoid deploying the functional equation (or related identities, such as Poisson summation) if they are unnecessary at a qualitative level (though I will note when the functional equation can be used to improve the quantitative results). As it turns out, all of the core results mentioned above can in fact be derived without ever invoking the functional equation, although one usually gets poorer numerical exponents as a consequence.
• Somewhat related to this, I will reduce the reliance on complex analytic methods as compared to more traditional presentations of the material, relying in some places instead on Fourier-analytic substitutes, or on results about harmonic functions. (But I will not go as far as deploying the primarily real-variable “pretentious” approach to analytic number theory currently in development by Granville and Soundararajan, although my approach here does align in spirit with that approach.)
• The discussion on sieve methods will be somewhat abridged, focusing primarily on the Selberg sieve, which is a good general-purpose sieve for qualitative applications at least.
• I will almost certainly avoid any discussion of automorphic forms methods.
• Similarly, I will not cover methods that rely on additive combinatorics or ergodic theory.
Of course, many of these additional topics are well covered in existing textbooks, such as the above-mentioned text of Iwaniec and Kowalski (or, for the finer points of sieve theory, the text of Friedlander and Iwaniec). Other good texts that can be used for supplementary reading are Davenport’s “Multiplicative number theory” and Montgomery-Vaughan’s “Multiplicative number theory I.”. As for prerequisites: some exposure to complex analysis, Fourier analysis, and real analysis will be particularly helpful, although we will review some of this material as needed (particularly with regard to complex analysis and the theory of harmonic functions). Experience with other quantitative areas of mathematics in which lower bounds, upper bounds, and other forms of estimation are emphasised (e.g. asymptotic combinatorics or theoretical computer science) will also be useful. Knowledge of algebraic number theory or arithmetic geometry will add a valuable additional perspective to the course, but will not be necessary to follow most of the material.
— 2. Notation —
In this course, all sums will be understood to be over the natural numbers unless otherwise specified, with the exception of sums over the variable ${p}$ (or variants such as ${p_1}$, ${p_2}$, etc.), which will be understood to be over primes.
We will use asymptotic notation in two contexts, one in which there is no asymptotic parameter present, and one in which there is an asymptotic parameter (such as ${x}$) that is going to infinity. In the non-asymptotic setting (which is the default context if no asymptotic parameter is explicitly specified), we use ${X = O(Y)}$, ${X \ll Y}$, or ${Y \gg X}$ to denote an estimate of the form ${|X| \leq CY}$, where ${C}$ is an absolute constant. In some cases we would like the implied constant ${C}$ to depend on some additional parameters such as ${k}$, in which case we will denote this by subscripts, for instance ${X = O_k(Y)}$ denotes the claim that ${|X| \leq C_k Y}$ for some ${C_k}$ depending on ${k}$.
In some cases it will instead be convenient to work in an asymptotic setting, in which there is an explicitly designated asymptotic parameter (such as ${x}$) going to infinity. In that case, all mathematical objects will be permitted to depend on this asymptotic parameter, unless they are explicitly referred to as being fixed. We then use ${X = O(Y)}$, ${X \ll Y}$, or ${Y \gg X}$ to denote the claim that ${|X| \leq CY}$ for some fixed ${C}$. Note that in slight contrast to the non-asymptotic setting, the implied constant ${C}$ here is allowed to depend on other parameters, so long as these parameters are also fixed. As such, the asymptotic setting can be a convenient way to manage dependencies of various implied constants on parameters. In the asymptotic setting we also use ${X = o(Y)}$ to denote the claim that ${|X| \leq c Y}$, where ${c}$ is a quantity which goes to zero as the asymptotic parameter goes to infinity.
Remark 3 In later posts we will make a distinction between implied constants ${C}$ that are effective (they can be computed, at least in principle, by some explicit method) and those at are ineffective (they can be proven to be finite, but there is no algorithm known to compute them in finite time).
We use ${d|n}$ to denote the assertion that ${d}$ divides ${n}$, and ${a\ (q)}$ to denote the residue class of ${a}$ modulo ${q}$.
We use ${1_E}$ to denote the indicator function of a set ${E}$, thus ${1_E(x) = 1}$ when ${x \in E}$ and ${1_E(x) = 0}$ otherwise. Similarly, for any mathematical statement ${S}$, we use ${1_S}$ to denote the value ${1}$ when ${S}$ is true and ${0}$ when ${S}$ is false. Thus for instance ${1_{2|n} = 1_{n\ (2) = 0}}$ is the indicator function of the even numbers.
We use ${|E|}$ to denote the cardinality of a set ${E}$.
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https://theronhitchman.wordpress.com/2012/12/02/book-review-pressleys-elementary-differential-geometry-2nd-ed/
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# Book Review: Pressley’s Elementary Differential Geometry, 2nd Ed
Pressley’s Elementary Differential Geometry
It is time to return to the book reviews! Our next book is Elementary Differential Geometry, 2nd Ed by Andrew Pressley. This is a pretty recent text. The first edition is from 2002, with the update published in 2010. The book has an attractive price point from Springer, and you can get it from Amazon.com for even cheaper.
Pressley’s desired approach is to make the subject as accessible as possible. In the preface, he writes:
Thus, for virtually all of the book, the only prerequisites are a good working knowledge of Calculus (including partial differentiation), Vectors and Linear Algebra (including matrices and determinants).
The tone of the writing bears this out, as does the author’s care to explain basic material. This text is definitely aimed at the modern student, and it conforms to the standard expectations for what a recent textbook on an advanced subject should look like.
Pressley has organized the material as follows:
• Curves in the plane and in space
• How much does a curve curve?
• Global properties of curves
• Surfaces in three dimensions
• Examples of surfaces
• The first fundamental form
• Curvature of Surfaces
• Gaussian, mean and principal curvatures
• Geodesics
• Gauss’ Theorema Egregium
• Hyperbolic Geometry
• Minimal surfaces
• The Gauss-Bonnet theorem
(As you can see, Pressley doesn’t use a serial comma. We are already at odds.) There are also three appendices, enumerated computer-science-style:
• A0. Inner product spaces and self-adjoint linear maps
• A1. Isometries of Euclidean Spaces
• A2. Möbius Transformations
Clearly, these are chosen to support some of the prerequisite material for describing curvature, understanding congruence, and dealing with hyperbolic geometry.
Keeping to the plan, I read chapter 4 Surfaces in three dimensions.
### Notable Features
As you can see from the chapter headings, Pressley wants to lay out the basics very carefully. There are whole chapters devoted to the basic process of defining curves (chapter 1) and defining smooth surfaces (chapter 4). The writing is direct but relatively friendly. You don’t get the “marble temple of mysteries” feel that some advanced textbooks can fall into.
There are over 200 exercises. (I am quoting the preface for this. I didn’t count.) There is a selection of hints for about 75 of them near the end of the text. (I counted that myself.) More importantly, there is also a 60 page section at the end of the book with fairly complete solutions to all of the exercises. Some seem a bit terse, but they do all seem to be addressed. This makes the text a really good choice for individual study. A person with the self-discipline to make an honest effort at each exercise would be glad of this feature.
Latitude and Longitude Coordinates on a Sphere, from Pressley
Some of the exercises I saw were pretty hard. That is, an undergraduate with the background listed in the preface would likely struggle mightily with some of them, though for the initiated they would be not difficult.
Exercise 4.1.4: Show that a unit cylinder can be covered by a single surface patch, but that the unit sphere cannot. (The second part requires some point set topology.)
That parenthetical remark is in the text.
Exercise 4.1.5: Show that every open subset of a surface is a surface.
A person with a fair amount of experience can dispatch those, but a student making the transition from calculus and linear algebra is likely to spin their wheels a long time. Those exercises just go straight to the “fiddly bits.”
We have the now standard, definition-theorem-proof style of exposition, and plenty of computer generated diagrams. Everything is labeled in one consecutive sequence in section.subsection.item style.
The examples are the ones you would expect, or, rather, they are the ones I expect. I recognize that I am not typical by a long way, having been trained in the subject formally, and now undertaking my seventh book review of this material. It is nice that the examples reoccur when new concepts arise.
Pressley has included more material than can be reasonably discussed in a one semester course. In particular, it looks as though you can, and should, pick a path through the text to one of the final three chapters. This gives the book a little flexibility, and it leaves more material to whet the appetites of ambitious students.
### A Complaint, only partly about the book
I have a big complaint to make, but I don’t think it is altogether fair to Prof Pressley. If anything, he is merely exemplifying a trend in mathematical exposition that has important uses, but which I have come to question about the construction of learning materials.
It is standard practice in mathematics to present things axiomatically. This has been going for a long time: I teach out of Euclid’s Elements, and it happens there. You get formal definitions and axioms first, theorems later, examples and discussion sometimes.
We don’t have to have the conversation about why this is so. We can all agree that it is generally a good thing to have the axiomatic structure in mathematical work.
I can’t really fault Pressley for doing things this way. This is
How Mathematics Is Supposed To Be Written.
(Did you hear the echo? I heard an echo.) If you want to prove theorems you actually suspect are true, this is how it goes.
But I don’t necessarily think it is the right thing for curricular materials. To really appreciate the nuances of mathematical definitions, one needs lots of examples. Even more, to even really feel a need for all of these crazy words (and find a will for keeping them straight), you have to have lots of funny friends that you can classify and organize with those words.
The upshot is that I believe that chapters 4 and 5 are in the wrong order.
Here is how the standard axiomatic approach leads to trouble for the potential reader in this text. Chapter 4 is about conveying the idea of a surface, and getting a definition down. But the first subsection 4.1 What is a surface?, opens with a page of definition-making in which we see the following terms:
• open subset ($\epsilon$ definition),
• open ball
• open interval
• open disc (Pressley is from the UK, so we get British English spellings)
• functions continuous at a point ($\epsilon - \delta$ definition)
• functions continuous in the large
• homeomorphism
• homeomorphic spaces
Then, and only then do we meet the first official definition, Definition 4.1.1, which gives the formal atlas of patches definition of a surface, essentially the notion of a topological 2-manifold. To Pressley’s credit, he doesn’t actually use the word manifold.
All of that is over in about a page of text, and then basic examples start. It seems to me that the preceding would be very hard to comprehend for anyone who hasn’t already mastered some point-set topology, or at least been exposed the ideas of metric spaces. The young, aspiring geometer just won’t have a sense of what those words are for, and why we have chosen to use all of them.
Before the chapter is out, we are introduced to regular surfaces, diffeomorphisms, the derivative of a function from one surface to another, orientability, the notion of a maximal atlas, the tangent plane as the set of all tangent vectors to curves through the given point which lie in the surface, and other things in this neighborhood of mathematics.
In a weird way, I think that all of this axiomatically clean development puts the cart before the horse for newcomers.
So, though Pressley has made an admirable attempt to be clear and helpful, I find I am dissatisfied. Basically this comes across as an extraordinarily friendly introduction, written so as to be useful more as a reference than as a learning tool. Again, not exactly the author’s fault…
### Verdict
A solid, mathematician’s introduction to the subject. Perhaps misses its mark of being truly accessible to the pre-analysis crowd. Any real flaws here are flaws in almost any advanced mathematics textbook. Instructors should make themselves aware of the book, as it could be a reasonable choice for an instructor who puts in the effort to help students through the transition.
This is a decent selection for someone with more advanced training who wishes to learn the subject by studying independently.
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http://encyclopedia.kids.net.au/page/cr/Crypt
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## Encyclopedia > Crypt
Article Content
# Crypt
A crypt is a large, stone chamber or vault used to store the deceased. Crypts are usually found in cemeteries but are also occasionally found on personal estates.
Weathy or prestigious families will often have a "family crypt" in which all members of the family are stored. Many royal families for example, have vast crypts containing the bodies of dozens of former royals.
All Wikipedia text is available under the terms of the GNU Free Documentation License
Search Encyclopedia
Search over one million articles, find something about almost anything!
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Simeon Poisson ... point ρ = 0, we get Laplace's equation: $\nabla^2 \phi = 0 \; .$ In 1812 Poisson discovered that Laplace's equation is valid only outside ...
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https://www.jobilize.com/course/section/verbal-inverse-trigonometric-functions-by-openstax?qcr=www.quizover.com
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# 5.6 Inverse trigonometric functions (Page 6/15)
Page 6 / 15
Find a simplified expression for $\text{\hspace{0.17em}}\mathrm{sin}\left({\mathrm{tan}}^{-1}\left(4x\right)\right)\text{\hspace{0.17em}}$ for $\text{\hspace{0.17em}}-\frac{1}{4}\le x\le \frac{1}{4}.$
$\frac{4x}{\sqrt{16{x}^{2}+1}}$
Access this online resource for additional instruction and practice with inverse trigonometric functions.
Visit this website for additional practice questions from Learningpod.
## Key concepts
• An inverse function is one that “undoes” another function. The domain of an inverse function is the range of the original function and the range of an inverse function is the domain of the original function.
• Because the trigonometric functions are not one-to-one on their natural domains, inverse trigonometric functions are defined for restricted domains.
• For any trigonometric function $\text{\hspace{0.17em}}f\left(x\right),\text{\hspace{0.17em}}$ if $\text{\hspace{0.17em}}x={f}^{-1}\left(y\right),\text{\hspace{0.17em}}$ then $\text{\hspace{0.17em}}f\left(x\right)=y.\text{\hspace{0.17em}}$ However, $\text{\hspace{0.17em}}f\left(x\right)=y\text{\hspace{0.17em}}$ only implies $\text{\hspace{0.17em}}x={f}^{-1}\left(y\right)\text{\hspace{0.17em}}$ if $\text{\hspace{0.17em}}x\text{\hspace{0.17em}}$ is in the restricted domain of $\text{\hspace{0.17em}}f.\text{\hspace{0.17em}}$ See [link] .
• Special angles are the outputs of inverse trigonometric functions for special input values; for example, $\text{\hspace{0.17em}}\frac{\pi }{4}={\mathrm{tan}}^{-1}\left(1\right)\text{\hspace{0.17em}}\text{and}\text{\hspace{0.17em}}\frac{\pi }{6}={\mathrm{sin}}^{-1}\left(\frac{1}{2}\right).$ See [link] .
• A calculator will return an angle within the restricted domain of the original trigonometric function. See [link] .
• Inverse functions allow us to find an angle when given two sides of a right triangle. See [link] .
• In function composition, if the inside function is an inverse trigonometric function, then there are exact expressions; for example, $\text{\hspace{0.17em}}\mathrm{sin}\left({\mathrm{cos}}^{-1}\left(x\right)\right)=\sqrt{1-{x}^{2}}.\text{\hspace{0.17em}}$ See [link] .
• If the inside function is a trigonometric function, then the only possible combinations are $\text{\hspace{0.17em}}{\mathrm{sin}}^{-1}\left(\mathrm{cos}\text{\hspace{0.17em}}x\right)=\frac{\pi }{2}-x\text{\hspace{0.17em}}$ if $\text{\hspace{0.17em}}0\le x\le \pi \text{\hspace{0.17em}}$ and $\text{\hspace{0.17em}}{\mathrm{cos}}^{-1}\left(\mathrm{sin}\text{\hspace{0.17em}}x\right)=\frac{\pi }{2}-x\text{\hspace{0.17em}}$ if $\text{\hspace{0.17em}}-\frac{\pi }{2}\le x\le \frac{\pi }{2}.$ See [link] and [link] .
• When evaluating the composition of a trigonometric function with an inverse trigonometric function, draw a reference triangle to assist in determining the ratio of sides that represents the output of the trigonometric function. See [link] .
• When evaluating the composition of a trigonometric function with an inverse trigonometric function, you may use trig identities to assist in determining the ratio of sides. See [link] .
## Verbal
Why do the functions $\text{\hspace{0.17em}}f\left(x\right)={\mathrm{sin}}^{-1}x\text{\hspace{0.17em}}$ and $\text{\hspace{0.17em}}g\left(x\right)={\mathrm{cos}}^{-1}x\text{\hspace{0.17em}}$ have different ranges?
The function $\text{\hspace{0.17em}}y=\mathrm{sin}x\text{\hspace{0.17em}}$ is one-to-one on $\text{\hspace{0.17em}}\left[-\frac{\pi }{2},\frac{\pi }{2}\right];\text{\hspace{0.17em}}$ thus, this interval is the range of the inverse function of $\text{\hspace{0.17em}}y=\mathrm{sin}x,$ $f\left(x\right)={\mathrm{sin}}^{-1}x.\text{\hspace{0.17em}}$ The function $\text{\hspace{0.17em}}y=\mathrm{cos}x\text{\hspace{0.17em}}$ is one-to-one on $\text{\hspace{0.17em}}\left[0,\pi \right];\text{\hspace{0.17em}}$ thus, this interval is the range of the inverse function of $\text{\hspace{0.17em}}y=\mathrm{cos}x,f\left(x\right)={\mathrm{cos}}^{-1}x.\text{\hspace{0.17em}}$
Since the functions $\text{\hspace{0.17em}}y=\mathrm{cos}\text{\hspace{0.17em}}x\text{\hspace{0.17em}}$ and $\text{\hspace{0.17em}}y={\mathrm{cos}}^{-1}x\text{\hspace{0.17em}}$ are inverse functions, why is $\text{\hspace{0.17em}}{\mathrm{cos}}^{-1}\left(\mathrm{cos}\left(-\frac{\pi }{6}\right)\right)\text{\hspace{0.17em}}$ not equal to $\text{\hspace{0.17em}}-\frac{\pi }{6}?$
Explain the meaning of $\text{\hspace{0.17em}}\frac{\pi }{6}=\mathrm{arcsin}\left(0.5\right).$
$\frac{\pi }{6}\text{\hspace{0.17em}}$ is the radian measure of an angle between $\text{\hspace{0.17em}}-\frac{\pi }{2}\text{\hspace{0.17em}}$ and $\text{\hspace{0.17em}}\frac{\pi }{2}$ whose sine is 0.5.
Most calculators do not have a key to evaluate $\text{\hspace{0.17em}}{\mathrm{sec}}^{-1}\left(2\right).\text{\hspace{0.17em}}$ Explain how this can be done using the cosine function or the inverse cosine function.
Why must the domain of the sine function, $\text{\hspace{0.17em}}\mathrm{sin}\text{\hspace{0.17em}}x,\text{\hspace{0.17em}}$ be restricted to $\text{\hspace{0.17em}}\left[-\frac{\pi }{2},\frac{\pi }{2}\right]\text{\hspace{0.17em}}$ for the inverse sine function to exist?
In order for any function to have an inverse, the function must be one-to-one and must pass the horizontal line test. The regular sine function is not one-to-one unless its domain is restricted in some way. Mathematicians have agreed to restrict the sine function to the interval $\text{\hspace{0.17em}}\left[-\frac{\pi }{2},\frac{\pi }{2}\right]\text{\hspace{0.17em}}$ so that it is one-to-one and possesses an inverse.
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
how did you get the value of 2000N.What calculations are needed to arrive at it
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http://www.ck12.org/physics/Resistor-Circuits/lesson/Resistor-Circuits/r16/
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<meta http-equiv="refresh" content="1; url=/nojavascript/"> Resistor Circuits ( Read ) | Physics | CK-12 Foundation
You are viewing an older version of this Concept. Go to the latest version.
# Resistor Circuits
%
Progress
Practice Resistor Circuits
Progress
%
Resistor Circuits
Students will use what they have learned from the previous lessons (ohm's law, resistors in series and resistors in parallel) and apply that knowledge to understand and solve more complicated resistor circuits.
### Key Equations
$V=IR$
$P=IV$ .
$R_{total} = R_1 + R_2 + R_3 + \ldots$
$\frac{1} {R_{total}} = \frac{1} {R_1} + \frac{1}{R_2} + \frac{1} {R_3} + \ldots$
Guidance
Table of electrical symbols and units
Name Electrical Symbol Units Analogy
Voltage ( $V$ Volts $(V)$
A water dam with pipes coming out at different heights. The lower the pipe along the dam wall, the larger the water pressure, thus the higher the voltage.
Examples : Battery, the plugs in your house, etc.
Current ( $I$ )
Amps $(A)$
$A = \mathrm{C/s}$
A river of water. Objects connected in series are all on the same river, thus receive the same current. Objects connected in parallel make the main river branch into smaller rivers. These guys all have different currents.
Examples : Whatever you plug into your wall sockets draws current
Resistance ( $R$ ) Ohm $(\Omega)$
If current is analogous to a river, then resistance is the amount of rocks in the river. The bigger the resistance the less current that flows
Examples : Light bulb, Toaster, etc.
#### Example 1
A more complicated circuit is analyzed.
Question: What is the total resistance of the circuit?
Answer: In order to find the total resistance we do it in steps (see pictures. First add the $90 \Omega$ and $10\Omega$ in series to make one equivalent resistance of $100\Omega$ (see diagram at below). Then add the $100\Omega$ to the $10\Omega$ in parallel to get one resistor of $9.1\Omega$ . Now we have two resistors in series, simply add them to get the total resistance of $29.1\Omega$ .
Question: What is the total current coming out of the power supply?
Answer: Use Ohm’s Law $(V=IR)$ but solve for current $(I=V/R)$ . $I_{total}=\frac{V_{total}}{R_{total}}=20V/2.91\Omega=0.69\ Amps$
Question: What is the power dissipated by the power supply?
Answer: $P=IV$ , so the total power equals the total voltage multiplied by the total current. Thus, $P_{total}=I_{total}V_{total}=(0.69A)(20V)=13.8W$ .
Question: How much power is the $20\Omega$ resistor dissipating?
Answer: The $20\Omega$ has the full 0.69Amps running through it because it is part of the ‘main river’ (this is not the case for the other resistors because the current splits). $P_{20 \Omega} = I^2_{20 \Omega} R_{20 \Omega} = (0.69A)^2 (20 \Omega) = 9.5W$
Question: If these resistors are light bulbs, order them from brightest to least bright.
Answer: The brightness of a light bulb is directly given by the power dissipated. So we could go through each resistor as we did the $20\Omega$ guy and calculate the power then simply order them. But, we can also think it out. For the guys in parallel the current splits with most of the current going through the $10\Omega$ path (less resistance) and less going through the $90\Omega+10\Omega$ path. Well the second path is ten times the resistance of the first, so it will have one tenth of the total current. Thus, there is approximately and 0.069 Amps going through the $90\Omega$ and $10\Omega$ path and 0.621Amps going through the $10\Omega$ path.
$P_{10 \Omega} &= I^2_{10\Omega}R_{10 \Omega}=(0.621A)^2(10\Omega)=3.8W\\P_{90+10\Omega} &= I^2_{90+10\Omega}R_{90 + 10 \Omega}=(0.069A)^2(100\Omega)=0.5W$
We now know that the $20\Omega$ is the brightest, $10\Omega$ is second and then the $90\Omega$ and last the $10\Omega$ (-these last two have same current flowing through them, so $90\Omega$ is brighter due to its higher resistance).
$^*$ Note: Adding up these two plus the 9.5W from the $20\Omega$ resistor gives us 13.8W, which is the total power previously calculated, so we have confidence everything is good.
### Time for Practice
1. What will the ammeter read for the circuit shown to the right?
2. You can use the simulation below to check your answer. Click on the blue arrow and select the part of the circuit you want to track. Then scroll down to the Data tab and you can see the current and voltage in different parts of the circuit.
3. Draw the schematic of the following circuit.
4. Analyze the circuit below.
1. Find the current going out of the power supply
2. How many Joules per second of energy is the power supply giving out?
3. Find the current going through the $75\ \Omega$ light bulb.
4. Find the current going through the $50\ \Omega$ light bulbs (hint: it’s the same, why?).
5. Order the light bulbs in terms of brightness
6. If they were all wired in parallel, order them in terms of brightness.
5. 4. Find the total current output by the power supply and the power dissipated by the $20\ \Omega$ resistor.
6. 5. You have a $600\;\mathrm{V}$ power source, two $10\ \Omega$ toasters that both run on $100\;\mathrm{V}$ and a $25\ \Omega$ resistor.
1. Show me how you would wire them up so the toasters run properly.
2. What is the power dissipated by the toasters?
3. Where would you put the fuses to make sure the toasters don’t draw more than 15 Amps?
4. Where would you put a $25$ Amp fuse to prevent a fire (if too much current flows through the wires they will heat up and possibly cause a fire)?
7. 6. Look at the following scheme of four identical light bulbs connected as shown. Answer the questions below giving a justification for your answer:
1. Which of the four light bulbs is the brightest?
2. Which light bulbs are the dimmest?
3. Tell in the following cases which other light bulbs go out if:
1. bulb $A$ goes out
2. bulb $B$ goes out
3. bulb $D$ goes out
4. Tell in the following cases which other light bulbs get dimmer, and which get brighter if:
1. bulb $B$ goes out
2. bulb $D$ goes out
8. 7. Refer to the circuit diagram below and answer the following questions.
1. What is the resistance between $A$ and $B$ ?
2. What is the resistance between $C$ and $B$ ?
3. What is the resistance between $D$ and $E$ ?
4. What is the the total equivalent resistance of the circuit?
5. What is the current leaving the battery?
6. What is the voltage drop across the $12\ \Omega$ resistor?
7. What is the voltage drop between $D$ and $E$ ?
8. What is the voltage drop between $A$ and $B$ ?
9. What is the current through the $25\ \Omega$ resistor?
10. What is the total energy dissipated in the $25\ \Omega$ if it is in use for 11 hours?
9. 8. You are given the following three devices and a power supply of exactly $120\;\mathrm{v}$ . $^*$ Device $X$ is rated at $60\;\mathrm{V}$ and $0.5\;\mathrm{A}$ $^*$ Device $Y$ is rated at $15\;\mathrm{w}$ and $0.5\;\mathrm{A}$ $^*$ Device $Z$ is rated at $120\;\mathrm{V}$ and $1800\;\mathrm{w}$ Design a circuit that obeys the following rules: you may only use the power supply given, one sample of each device, and an extra, single resistor of any value (you choose). Also, each device must be run at their rated values.
1. $0.5\mathrm{A}$
2. .
3. a. $0.94 \;\mathrm{A}$ b. $112 \;\mathrm{W}$ c. $0.35 \;\mathrm{A}$ d. $0.94 \;\mathrm{A}$ e. $50, 45, 75 \ \Omega$ f. both $50 \ \Omega$ resistors are brightest, then $45 \ \Omega$ , then $75 \ \Omega$
4. a. $0.76 \;\mathrm{A}$ b. $7.0 \;\mathrm{W}$
5. b. $1000 \;\mathrm{W}$
6. .
7. a. $9.1 \ \Omega$ b $29.1 \ \Omega$ c. $10.8 \ \Omega$ d. $26.8 \ \Omega$ e. $1.8\mathrm{A}$ f. $21.5\mathrm{V}$ g. $19.4\mathrm{V}$ h. $6.1\mathrm{V}$ i. $0.24\mathrm{A}$ j. $16 \;\mathrm{kW}$
8. .
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https://www.jiskha.com/questions/405128/suppose-that-the-proportions-of-blood-phenotypes-in-a-particular-population-are-a-follows
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# statistics
Suppose that the proportions of blood phenotypes in a particular population are a follows:
A = .42
B = .10
AB = .04
O = .44
Assuming that the phenotypes of two randomly selected indiviuals are independent of one another, what is the probablility that both phenotypes are O? What is the probablility that the phenotypes of two randomly selected individuals match?
I'm really stuck on how to approach and solve this problem. From what I see, it says they are independent so would we need to use a formula of the kind
P(O Phenotype) = P(A) * P(B)
where A and B are the events of two randomly selected individuals?
1. 👍
2. 👎
3. 👁
1. Right!
1. 👍
2. 👎
2. now i don't know what to do frrom there
1. 👍
2. 👎
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https://www.physicsforums.com/threads/how-do-we-measure-particle-momentum.227477/
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# How do we measure particle momentum?
1. Apr 8, 2008
### pellman
How do we measure a quantum particle's momentum?
2. Apr 8, 2008
### lbrits
The field of spectroscopy is devoted to that issue.
3. Apr 8, 2008
### pam
Momentum p is most commonly measured by curvature in a magnetic field B.
R=p/qB.
4. Apr 8, 2008
### ZapperZ
Staff Emeritus
There are no unique methods to do this. In angle-resolved photoemission spectroscopy (ARPES), the detector has a finite rectangular slit in which one dimension is the energy, while the other is the momentum of the emitted photoelectrons. So you would get a raw image of something like my avatar. For certain types of material (such as 2D, layered material), the transverse momentum of the photoelectrons corresponds to the transverse momentum of such electrons while it is in the material.
Believe it or not, the diffraction pattern that you see on the screen corresponds to the transverse momentum of whatever particle that passed through the single slit.
Zz.
5. Apr 8, 2008
### pellman
So do all the methods amount to making a position measurement from which we infer the momentum? How does that square with the uncertainty principle?
6. May 12, 2010
### sweet springs
Hi.
Measurement of momentum is always achieved by measurement of position, so I assume that observation of momentum is not how it IS but how it WAS . After measurement of momentum value p, the state cannot keep on |p>. It is a kind of destructive observation.
Regards.
7. May 12, 2010
### SpectraCat
This is a very important point that IMO is *way* under-emphasized in discussions of QM. We talk rather blithely about measurement of observables in an experimental sense, however the reality is that every measurement we can actually *do* involves either an explicit or implicit measurement of position to one extent or another. The closest thing to a counter-example that I can think of right away might be a direct absorption spectroscopy experiment on a gas confined to a large-volume sample cell. In that case the "uncertainty" in the position of the gas molecules giving rise to the observed spectral lines is fairly large, however you can still say with certainty that they must have been somewhere inside the cell at the time they absorbed a photon(s). So even there there is an implicit measurement of position involved.
At least in my own academic arc, which included a significant amount of formal QM training, this aspect was "pushed under the rug" to the extent that I am not even sure how to address it! I have thought of it on my own several times, and then pushed it back under the rug with a rationalization such as, "well, it must not really be important, or it would be addressed explicitly in QM texts". However, in light of many of the discussions I have participated in here, I think this deserves a closer look. For example, if we look at Zz's answer above, you see that the momentum is inferred from a position measurement of displacement along a given spatial axis. Thus the momentum observable was never really measured at all! Yet we consistently talk as though it had been directly measured. Couldn't this lead to fundamental mis-interpretations of such measurements?
8. May 16, 2010
### DaTario
I would say that neither do position observable.
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http://wias-berlin.de/publications/wias-publ/run.jsp?lang=0&template=abstract&type=Preprint&year=2002&number=758
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WIAS Preprint No. 758, (2002)
Eigen mode computation of microwave and laser structures including PML
Authors
• Hebermehl, Georg
• Hübner, Friedrich-Karl
• Schlundt, Rainer
ORCID: 0000-0002-4424-4301
• Tischler, Thorsten
• Zscheile, Horst
• Heinrich, Wolfgang
2010 Mathematics Subject Classification
• 35Q60 65F15 65N22
Keywords
• Microwave device, Optoelectronic device, Simulation, Maxwell's equations, PML boundary condition, Eigenvalue problem
DOI
10.20347/WIAS.PREPRINT.758
Abstract
The field distribution at the ports of the transmission line structure is computed by applying Maxwell's equations to the structure. Assuming longitudinal homogeneity an eigenvalue problem can be derived, whose solutions correspond to the propagation constants of the modes. The nonsymmetric sparse system matrix is complex in the presence of losses and Perfectly Matched Layer. The propagation constants are found solving a sequence of eigenvalue problems of modified matrices with the aid of the invert mode of the Arnoldi method. Using coarse and fine grids, and a new parallel sparse linear solver, the method, first developed for microwave structures, can be applied also to high dimensional problems of optoelectronics.
Appeared in
• Scientific Computing in Electrical Engineering, Eds. W. H. A. Schilders, E. J. W. ter Maten, St. H. M. J. Houben, Mathematics in Industry, Springer Verlag, Vol. 4, pp. 196--205, 2004
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http://mathhelpforum.com/advanced-algebra/105621-finding-spanning-set-null-space-print.html
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# Finding a spanning set of a null space
• Oct 2nd 2009, 02:38 AM
Mathmaticious
Finding a spanning set of a null space
Let U be the subspace of R4 given by:
U = nullspace of the matrix
[0 0 2 3 ]
[0 -3 -2 -2 ]
Find a spanning set for U.
Any and all help will be awesome.
Not sure how to start at all (Worried)
Cheers
• Oct 2nd 2009, 05:41 AM
Swlabr
Quote:
Originally Posted by Mathmaticious
Let U be the subspace of R4 given by:
U = nullspace of the matrix
[0 0 2 3 ]
[0 -3 -2 -2 ]
Find a spanning set for U.
Any and all help will be awesome.
Not sure how to start at all (Worried)
Cheers
The first thing to do is to find out what the nullspace of your matrix actually is - can you find a general form that these vectors take?
Can you think of a spanning set for this vector space? For instance, if they were of the form $\{(2a,5b, 6c,d): a, b, c, d \in \mathbb{F} \}$ then your space would be spanned by the vectors $(2,0,0,0)$, $(0,5,0,0)$, $(0,0,6,0)$ and $(0,0,0,1)$.
I hope that that helps...
• Oct 2nd 2009, 07:47 AM
aman_cc
Quote:
Originally Posted by Swlabr
The first thing to do is to find out what the nullspace of your matrix actually is - can you find a general form that these vectors take?
Can you think of a spanning set for this vector space? For instance, if they were of the form $\{(2a,5b, 6c,d): a, b, c, d \in \mathbb{F} \}$ then your space would be spanned by the vectors $(2,0,0,0)$, $(0,5,0,0)$, $(0,0,6,0)$ and $(0,0,0,d)$.
I hope that that helps...
1. In your example $\{(2a,5b, 6c,d): a, b, c, d \in \mathbb{F} \}$ what is the relevance of 2,5,6? Isn't it just same as $\{a,b,c,d): a, b, c, d \in \mathbb{F} \}$
2. Nevertheless, is there a good/structured approach to find dimension and basis of a space given by something like $\{a,2a,a+b,b): a, b \in \mathbb{F} \}$
• Oct 2nd 2009, 08:17 AM
Swlabr
Quote:
Originally Posted by aman_cc
1. In your example $\{(2a,5b, 6c,d): a, b, c, d \in \mathbb{F} \}$ what is the relevance of 2,5,6? Isn't it just same as $\{a,b,c,d): a, b, c, d \in \mathbb{F} \}$
Yes. Yes it is. No excuses, other than to point that I was still correct...I mean, 4+2=80712/13452...
Quote:
2. Nevertheless, is there a good/structured approach to find dimension and basis of a space given by something like $\{a,2a,a+b,b): a, b \in \mathbb{F} \}$
Yes. The answer to your problem is either one or two, but is clearly two as the entries in the 1st and 4th positions are independent of one another. It is no more than the number of variables given, but can be less if they cancel out with one another.
$(1, 2, 1, 0)$ and $(0, 0, 1, 1)$ span the space you gave.
• Oct 2nd 2009, 08:24 AM
aman_cc
Quote:
Originally Posted by Swlabr
Yes. Yes it is.
Yes. The answer to your problem is either one or two, but is clearly two as the entries in the 1st and 4th positions are independent of one another. It is no more than the number of variables given, but can be less if they cancel out with one another.
$(a, 2a, a, 0)$ and $(0, 0, b, b)$ span the space you gave.
Thanks Swalbr
If you won't mind can you explain why you say - "It is no more than the number of variables given"?
Also is there is a formal way to solve such a problem - I am looking at something equivalent to row-reduction to find the rank of matrix. Thanks
• Oct 2nd 2009, 08:32 AM
Swlabr
Quote:
Originally Posted by aman_cc
Thanks Swalbr
If you won't mind can you explain why you say - "It is no more than the number of variables given"?
Also is there is a formal way to solve such a problem - I am looking at something equivalent to row-reduction to find the rank of matrix. Thanks
In the vectors you gave you had an $a$ and a $b$, so two variables. Say you had a subspace of vectors where you can write them like you did but with $n>0$ variables. Then you can easily split your general form into $n$ vectors each with precisely one variable. In each vector you can take out this variable as a common factor, and the set of all of these vectors (the ones with the variables removed) forms a spanning set. You may be able to reduce this spanning set, if not then it is a basis.
Does that make sense?
Note also that a vector space cannot have a basis of order greater than the length of the vector...
• Oct 2nd 2009, 08:35 AM
aman_cc
Thanks. I need to think this carefully though. I was also wondering if it has to do something with the fact that each component is a linear combination of the variables. What happens if we relax that - for e.g. {a^2,b^3,a+b^-1,b} (I have not checked if it is a sub-space.)
• Oct 2nd 2009, 03:48 PM
HallsofIvy
I presume you mean the matrix
$\begin{bmatrix}0 & 0 & 2 & 3 \\ 0 & -3 & -2 & -2\end{bmatrix}$
The kernel is, by definition, the set of vectors $\begin{bmatrix}x \\ y \\ z \\ t\end{bmatrix}$ such that
$\begin{bmatrix}0 & 0 & 2 & 3 \\ 0 & -3 & -2 & -2\end{bmatrix}\begin{bmatrix}x \\ y \\ z \\ t\end{bmatrix}= \begin{bmatrix}0 \\ 0 \end{bmatrix}$
which means we must have 2z+ 3t= 0 and -3y- 2z- 2t= 0. Those two equations drop the dimension from 4 to 2. We can write z= (-3/2)t and then y= (-1/3)(2z+ 2t)= (-1/3)(-3t+ 2t)= (1/3)t. That is, y and z depend on t while x, since it does not appear in the equations can be anything. Use x and t as "free variables". Any vector in the kernel are of the form $\begin{bmatrix}x \\ (1/3)t \\ (-3/2)t \\ t\end{bmatrix}= x\begin{bmatrix}1 \\ 0 \\ 0 \\ 0\end{bmatrix}+ t\begin{bmatrix}0 \\ 1/3 \\ -3/2 \\ 1\end{bmatrix}$
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https://www.variousconsequences.com/2012/07/
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## Saturday, July 28, 2012
### Mixed Effects for Fusion
It seems like the folks at Prometheus Fusion Perfection have matured their equipment and operations to the point of being able to run on a fairly repeatable basis. Right now they are working on a Symmetry test of their polywell. I posted a link to an example design/analysis using R that would allow a basic response surface for the device to be estimated (script embedded below the fold). It uses AlgDesign for the blocking by shot, and lme4 to fit a model that includes a random effect to account for shot-to-shot variation.
## Monday, July 23, 2012
### Convergence for Falkner-Skan Solutions
About 6 months ago Dan Hughes sent me a link to an interesting paper on "chaotic" behavior in the trajectory of iterates in a numerical Falkner-Skan solution. It struck me that the novel results reported in that paper were an artifact of the numerical method, and had little to do with any "chaotic" physics that might be going on in boundary layers or other systems that might be well described by this equation. This is similar to the point I made in the Fun with Filip post: the choice of numerical method matters. Do not rush to judgment about problems until you have brought the most appropriate methods to bear.
There are some things about the paper that are not novel, and others that seem to be nonsense. It is well-known that there can be multiple solutions at given parameter values (non-uniqueness) for this equation, see White. There is the odd claim that "the flow starts to create shock waves in the medium [above the critical wedge angle], which is a representation of chaotic behavior in the flow field." Weak solutions (solutions with discontinuities/shocks) and chaotic dynamics are two different things. They use the fact that the method they choose does not converge when two solutions are possible as evidence of chaotic dynamics. Perhaps the iterates really do exhibit chaos, but this is purely an artifact of the method (i.e. there is no physical time in this problem, only the pseudo-time of the iterative scheme). By using a different approach you will get different "dynamics", and with proper choice of method, can get convergence (spectral even!) to any of the multiple solutions depending on what initial condition you give your iterative scheme. They introduce a parameter, $$\eta_{\infty}$$, for the finite value of the independent variable at "infinity" (i.e. the domain is truncated). There is nothing wrong with this (actually it's a commonly used approach for this problem), but it is not a good idea to solve for this parameter as well as the shear at the wall in your Newton iteration. A more careful approach of mapping the boundary point "to infinity" as the grid resolution is increased (following one of Boyd's suggested mappings) removes the need to solve for this parameter, and gives spectral convergence for this problem even in the presence of non-uniqueness and the not uncommon vexation of a boundary condition defined at infinity (all of external aerodynamics has this helpful feature).
## Sunday, July 22, 2012
### VV&UQ for Historic Masonry Structures
What a neat application of verification, validation and uncertainty quantification (VV&UQ) methods! The paper is Uncertainty quantification in model verification and validation as applied to large scale historic masonry monuments.
Abstract: This publication focuses on the Verification and Validation (V&V) of numerical models for establishing confidence in model predictions, and demonstrates the complete process through a case study application completed on the Washington National Cathedral masonry vaults. The goal herein is to understand where modeling errors and uncertainty originate from, and obtain model predictions that are statistically consistent with their respective measurements. The approach presented in this manuscript is comprehensive, as it considers all major sources of errors and uncertainty that originate from numerical solutions of differential equations (numerical uncertainty), imprecise model input parameter values (parameter uncertainty), incomplete definitions of underlying physics due to assumptions and idealizations (bias error) and variability in measurements (experimental uncertainty). The experimental evidence necessary for reducing the uncertainty in model predictions is obtained through in situ vibration measurements conducted on the masonry vaults of Washington National Cathedral. By deploying the prescribed method, uncertainty in model predictions is reduced by approximately two thirds.
Highlights:
• Developed a finite element model of Washington National Cathedral masonry vaults.
• Carried out code and solution verification to address numerical uncertainties.
• Conducted in situ vibration experiments to identify modal parameters of the vaults.
• Calibrated and validated model to mitigate parameter uncertainty and systematic bias.
• Demonstrated a two thirds reduction in the prediction uncertainty through V&V.
Keywords: Gothic Cathedral; Modal analysis; Finite element modeling; Model updating; Bayesian inference; Uncertainty quantification
I haven't read the full-text yet, but it looks like a coherent (Bayesian) and pragmatic approach to the problem.
## Saturday, July 21, 2012
### Rocket Risk
As reported on ParabolicArc, NASA awarded SpaceX a contract to launch one of their science payloads. The topic of NASA's assessment of launch service provider risk naturally came up. NASA has published payload value, and risk rating guidelines.
If we assume that each launch has the same probability of success, then these are simple risk calculations to make, e.g. see these slides. The posterior probability of success, $$\theta$$, is
$p(\theta | r, n) = \mathrm{Beta}(\alpha + r, \beta + n - r)$
where $$r$$ is the number of successes, $$n$$ is the number of trials, and $$\alpha$$ and $$\beta$$ are parameters of the Beta distribution prior. What values of parameters should we choose for the prior? I like $$\alpha=\beta=1$$, you could probably make a case for anything consistent with $$\alpha+\beta-2=0$$. Many people say that risk = probability * consequence. I don't know what the consequences are in this case, and under that approach NASA's chart doesn't make any sense (you could have a low risk with a high probability of failing to launch an inconsequential payload), so I'll stick to just the probabilities of launch success, and leave worrying about the consequences to others.
Since NASA specifies a number of successes in a row (consecutive) then there is already an indication that assuming the trials independent and identically distributed (i.i.d.) is unrealistic. If your expensive rocket blows up, you usually do your best to find out why and fix the cause of failure. That way on the next launch your rocket has a higher probability of success than it previously did.
## Saturday, July 7, 2012
### DARPA's Silver Birds
NextBigFuture caries the story of DARPA's continuing Integrated Hypersonics program.
Eugen Sänger, father of the hypersonic boost-glide global bomber concept, may well have been prescient when he wrote, "Nevertheless, my silver birds will fly!"
## Wednesday, July 4, 2012
### Experimental Designs with Orthogonal Basis
In comments on the Fun with Filip post I mentioned that the basis should be taken into consideration for experimental design. This script generates a couple different sample sets for estimating a sixth order 2-dimensional response surface.
## Monday, July 2, 2012
### HIFiRE 2 Videos
Lug camera video of the HIFiRE (Hypersonic International Flight Research and Experimentation) flight 2 launch:
Multiple high-speed views:
Additional coverage on Parabolic Arc.
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http://mathhelpforum.com/calculus/198320-volume-body-obtained-rotating-around-x-axis-y-axis.html
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# Math Help - Volume of body obtained by rotating around the x axis and y axis.
1. ## Volume of body obtained by rotating around the x axis and y axis.
Hi,
If y= 4x^3+3x^2-4x-3, calculate the volume of the body obtained by rotating y around 1) the x axis 2) the y axis.
I'm at a bit of a loss here. I know the formula for rotating about the x axis is the integral of pi.y^2 and integral of pi.x^2 for rotation about the y axis.
For the x axis rotation, i presume I have to square out the whole function and then integrate bit by bit. However, for rotation about the y axis, how do I express x^2 in terms of y? Bit confused, would appreciate help!
2. ## Re: Volume of body obtained by rotating around the x axis and y axis.
First, find the roots $4x^3+3x^2-4x-3=0$.
3. ## Re: Volume of body obtained by rotating around the x axis and y axis.
Hi.
I've factorised to get(x-1)(x+1)(4x+3). So the roots are x=1, x=-1 and x=-3/4
4. ## Re: Volume of body obtained by rotating around the x axis and y axis.
around the x-axis:
$V_x=\pi\int_{-1}^{1}(4x^3+3x^2-4x-3)^2\,dx=\ldots=\frac{1264}{105}\,\pi$
5. ## Re: Volume of body obtained by rotating around the x axis and y axis.
Thanks but do you know how to do it about the y axis? Can i say at y=0 that the above function squared then equals zero and then bring the x squared term over to the left and side...
6. ## Re: Volume of body obtained by rotating around the x axis and y axis.
Sorry, Just realised , can I use the shell method for rotating about the y axis? i.e that the volume of a solid rotated about the y axis can be written as the integral of 2pixf(x) between the limits a and b?
7. ## Re: Volume of body obtained by rotating around the x axis and y axis.
Originally Posted by orlacoon
Hi,
If y= 4x^3+3x^2-4x-3, calculate the volume of the body obtained by rotating y around 1) the x axis 2) the y axis.
I'm at a bit of a loss here. I know the formula for rotating about the x axis is the integral of pi.y^2 and integral of pi.x^2 for rotation about the y axis.
For the x axis rotation, i presume I have to square out the whole function and then integrate bit by bit. However, for rotation about the y axis, how do I express x^2 in terms of y? Bit confused, would appreciate help!
I see your problem. are you sure you have given us the complete question. For example it does not tell us between what values of x they are asking.
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http://physics.stackexchange.com/tags/gauge-theory/new
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# Tag Info
## New answers tagged gauge-theory
5
The gauge connection is not unique, and this has nothing to do with the presence of matter fields. Let $\Sigma$ be our space-time, $P$ a principal $G$-bundle, and $\mathcal{A}$ the space of connections on $P$. Then, gauge transformations $t : P \to G$, forming the group of gauge transformations $\mathcal{G}$ have an action on $\mathcal{A}$ given by $$A ... 5 Yes, one traditional alternative to the path integral formalism is the operator formalism. For QED with abelian gauge group, the old quantization formulation is the Gupta-Bleuler formulation. For QCD/Yang-Mills theory with non-abelian gauge group, the Gupta-Bleuler formulation is replaced by the BRST formulation. The BRST formulation exists in at least 3 ... 3 There exists an extensive literature for discretization of the abelian and the non-abelian gauge theories, known as lattice QED and lattice QCD, respectively. Here we will only sketch the main idea. Let us for simplicity use Euclidean signature (+,+,+,+). A small Wilson-loop$$\tag{1} W~=~{\rm Tr}{\cal P}e^{ig\int_{\gamma}A}$$lies approximately in a ... 2 The key point in all of this is that general relativity is a gauge theory, and, as the saying goes, "the gauge always hits twice" (apparently attributed to Claudio Teitelboim). What this means is that (1) you have an arbitrary freedom in defining your evolution, corresponding to the ability to make gauge transformations, and (2) some of the evolution ... 2 It is interesting to look at a linearized version of gravity, with g_{\mu\nu} = \eta_{\mu\nu} + h_{\mu\nu} If you choose the Lorentz gauge :$$\partial^\mu \bar h_{\mu\nu}=0 \quad\quad \bar h_{\mu\nu} = h_{\mu\nu} - \frac{1}{2} h^i_i \,\eta_{\mu\nu} \tag{0}$$the equations of movement in the vaccuum are simply :$$\square \bar h_{\mu\nu}=0 \tag{1}$$... 1 It isn't classical field theory, but there are a few features of using of 4-potential in QFT. The first one is that 4-potential as 4-vector can't be used for describing massless photons. It is because the fact that it must describe massless particles leads to its transformations not as 4-vector under the Lorentz group. Specifically,$$ A^{\mu} \to ...
2
If your question is asking whether the four-potential is more useful in classical electromagnetism from a purely computational standpoint, the answer would be no. It's not to say that it isn't useful, it's just that it only groups together two equations in the Lorentz gauge that are already useful themselves. The Lorentz gauge, $$\Box\phi = ... 5 Why do we gauge-fix the path integral in the first place? If we were doing lattice gauge theory, we didn't need to gauge-fix. But in the continuum case, (the Hessian of) the action for a generalized^1 gauge theory has zero-directions that lead to infinite factors when performing the path integral over gauge orbits. In a BRST formulation (such as, e.g., the ... 4 We only have one contribution from each gauge-equivalent matter field configuration: Let P be the principal G-bundle associated to our gauge theory on the spacetime \mathcal{M} (for simplicity, assume it is \mathcal{M} \times G. The matter fields are constructed as sections of an associated vector bundle P \times_G V_\rho, where V_\rho is a ... 2 We have no choice. Let G be our gauge group and \Sigma our spacetime. Then, for the theory to actually be gauge invariant, every field must have a defined action of the gauge group upon it, i.e. every field must transform in a representation of this group:$$\phi : \Sigma \to V_\rho \text{ where there is a group morphism } \rho : G \to ...
3
Feynman diagrams are more than just the Lagrangian. They can be acquired by expanding the path integral of the theory into a perturbative series. There is a priori no reason to assume that all quantities needed in order to produce sensible results are consistent with gauge invariance. One possible issue is the problem of regularization: the way your ...
2
You may always promote "couplings constants" (charge, mass, etc...) to fields. Now, as a physicist, you need to make some contact with reality. So you have to tell why and which field you are using (for instance the Higgs field (up to a constant), which has a $SU(2)$ charge, is used to replace a constant mass coupling in the interaction \$m (\bar e_R e_L + ...
1
The Einstein equivalence principle states : The outcome of any local non-gravitational experiment in a freely falling laboratory is independent of the velocity of the laboratory and its location in spacetime. Emphasis added. Note that this principle has done well in explaining quite a few things about gravity. So there is no a priori reason why you ...
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https://socratic.org/questions/the-same-quantity-of-electricity-was-passed-through-separate-molten-samples-of-a
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Chemistry
Topics
# The same quantity of electricity was passed through separate molten samples of aluminium oxide and sodium chloride. How many moles of sodium will be produced if 0.2 moles of oxygen gas were formed?
Oct 1, 2015
$\text{0.8 moles Na}$
#### Explanation:
The overall reactions look like this
$2 {\text{Al"_2"O"_text(3(l]) -> 4"Al"_text((l]) + 3"O}}_{\textrm{2 \left(g\right]}} \uparrow$
and
$2 {\text{Na"^(+)"Cl"^(-) -> 2"Na"_text((s]) + "Cl}}_{\textrm{2 \left(g\right]}} \uparrow$
Now, the half-reactions that are of interest to you are
$6 \stackrel{\textcolor{b l u e}{- 2}}{{\text{O") -> 3stackrel(color(blue)(0))("O}}_{2}} + 12 {e}^{-}$
Oxygen is being oxidized to oxygen gas.
$\stackrel{\textcolor{b l u e}{+ 1}}{\text{Na"^(+)) + 1e^(-) -> stackrel(color(blue)(0))("Na}}$
Sodium is being reduced to sodium metal.
So, how many moles of electrons are needed to make one mole of oxygen gas?
Take a look at the mole ratio that exists between oxygen gas, ${\text{O}}_{2}$, and the number of moles of electrons that take part in oxygen's oxidation to oxygen gas.
Well, if you have twelve moles of electrons for every three moles of oxygen gas, then it follows that you need four moles of electrons to make one mole of oxygen gas.
This means that $\text{0.2 moles}$ of oxygen gas needed
0.2color(red)(cancel(color(black)("moles O"""_2))) * ("12 moles e"""^(-))/(3color(red)(cancel(color(black)("moles O"""_2)))) = "0.8 moles e"""^(-)
Now look at the reduction of sodium cations to sodium metal. Notice that you need one mole of electrons to produce one mole of sodium metal.
This means that you will produce
0.8color(red)(cancel(color(black)("moles e"""^(-)))) * "1 mole Na"/(1color(red)(cancel(color(black)("moles e"""^(-))))) = color(geen)("0.8 moles Na")
##### Impact of this question
985 views around the world
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https://nyuscholars.nyu.edu/en/publications/scenario-submodular-cover
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# Scenario submodular cover
Nathaniel Grammel, Lisa Hellerstein, Devorah Kletenik, Patrick Lin
Research output: Chapter in Book/Report/Conference proceedingConference contribution
## Abstract
We introduce the Scenario Submodular Cover problem. In this problem, the goal is to produce a cover with minimum expected cost, with respect to an empirical joint probability distribution, given as input by a weighted sample of realizations. The problem is a counterpart to the Stochastic Submodular Cover problem studied by Golovin and Krause [6], which assumes independent variables. We give two approximation algorithms for Scenario Submodular Cover. Assuming an integervalued utility function and integer weights, the first achieves an approximation factor of O(logQm), where m is the sample size and Q is the goal utility. The second, simpler algorithm achieves an approximation factor of O(logQW), where W is the sum of the weights. We achieve our bounds by building on previous related work (in [4,6,15]) and by exploiting a technique we call the Scenario-OR modification. We apply these algorithms to a new problem, Scenario Boolean Function Evaluation. Our results have applciations to other problems involving distributions that are explicitly specified by their support.
Original language English (US) Approximation and Online Algorithms - 14th International Workshop, WAOA 2016, Revised Selected Papers Monaldo Mastrolilli, Klaus Jansen Springer Verlag 116-128 13 9783319517407 https://doi.org/10.1007/978-3-319-51741-4_10 Published - 2017 14th International Workshop on Approximation and Online Algorithms, WAOA 2016 - Aarhus, DenmarkDuration: Aug 25 2016 → Aug 26 2016
### Publication series
Name Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 10138 LNCS 0302-9743 1611-3349
### Other
Other 14th International Workshop on Approximation and Online Algorithms, WAOA 2016 Denmark Aarhus 8/25/16 → 8/26/16
## ASJC Scopus subject areas
• Theoretical Computer Science
• Computer Science(all)
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Dive into the research topics of 'Scenario submodular cover'. Together they form a unique fingerprint.
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http://mathhelpforum.com/advanced-algebra/194879-continuum-mechanics-elasticity-help-re-polar-decomposition-theorem.html
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# Math Help - Continuum Mechanics/Elasticity help re: Polar Decomposition Theorem
1. ## Continuum Mechanics/Elasticity help re: Polar Decomposition Theorem
That is a model question. b) is just stating the theorem, which is as follows in my notes:
If a linear transformation F is invertible with det F > 0, then there exists unique symmetric positive-definite linear transformations U and V, and a unique proper orthogonal transofrmation R, such that:
RU = F = VR.
I'm just having a bit of trouble applying the theorem, specifically "Show that the deformation can be considered to be the result of three simple stretches followed by a rotation. Explain the precise nature of the stretches and rotation.
Looking through the printed and my written notes, it revolves around the homogeneous deformation:
x = A + H(X - A)
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https://cran.dcc.uchile.cl/web/packages/epiGWAS/vignettes/epistasis.html
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# Robust epistasis detection with epiGWAS
#### 2019-09-08
In this vignette, we cover the epistasis detection methods implemented in this package. The methods can be partitioned into two main categories: those based on modified outcome, and those based on outcome weighted learning. Both methods recover pure epistatic interactions with a predetermined variant, referred to as the target. The target can be drawn from the literature, experiments or top hits in previous GWAS. Narrowing the scope around a single variant is made possible by propensity scores (Rosenbaum and Rubin 1983) which, for genomic data, model the linkage disequilibrium (LD) dependency between the target and neighboring variants. We include them differently in outcome weighted learning and modified outcome in order to identify the SNPs interacting with the target.
The methods are briefly reviewed in this vignette before showcasing their performance on a dataset of simulated genotypes. For more details, we refer the prospective user to (Slim et al. 2018).
## Phenotype-genotype decomposition
We first consider a triplet of random variables $$\left(X, A, Y\right)$$:
• $$Y$$ denotes a binary (for case-control studies) or continuous phenotype (for quantitative GWAS).
• $$X= \left(X_1,\cdots, X_p\right) \in \lbrace 0, 1, 2\rbrace^{p}$$ represents a genotype with $$p$$ single-nucleotide polymorphisms (SNPs). $$X_j$$ encodes the number of minor alleles of SNP j (allelic dosage).
• $$A$$ is a $$(p+1)$$-th SNP that is encoded as $$\lbrace -1, +1\rbrace$$. Let $$\underline{A} = (A+1)/2$$ be a second binarized version of $$A$$ with values in $$\lbrace 0,+1\rbrace$$. Depending on the binarization rule for the SNP values $$\lbrace 0, 1, 2\rbrace$$, we can model both dominant and recessive mechanisms.
The symmetric encoding of $$A$$ allows the following genotype-phenotype decomposition: $Y = \mu(X) + \delta(X)\cdot A + \epsilon,$ where $$\epsilon$$ is a zero mean random variable and \left\{ \begin{aligned} \mu (X) &= \frac{1}{2}\left[\mathbb{E}(Y\lvert A=+1,X)+\mathbb{E}(Y\lvert A=-1,X)\right] \,,\\ \delta (X) &= \frac{1}{2}\left[\mathbb{E}(Y\lvert A=+1,X)-\mathbb{E}(Y\lvert A=-1,X)\right] \,. \end{aligned} \right.
The above decomposition separates the main effects term $$\mu(X)$$ from $$\delta(X)\cdot A$$, which models the pure epistatic effects of the SNPs in $$X$$ with the target SNP $$A$$. Under a sparsity assumption for $$\delta(X)$$, detecting epistasis amounts to recovering the support of $$\delta(X)$$. However, for a given sample, we only observe one of the two possibilities (either $$A = +1$$ or $$A = -1$$), making it impossible to directly estimate the term $$\delta(X)$$. To overcome this problem, we make use of the propensity score $$\pi(A\lvert X)$$. Mathematically speaking, it corresponds to the conditional probability of $$A$$ given $$X$$. In our case, where $$A$$ and $$X$$ are SNPs, $$\pi(A\lvert X)$$ models the LD between $$A$$ and $$X$$. The first category of methods, which we call modified outcome, incorporates $$\pi(A\lvert X)$$ in the outcome. The second category, outcome weighted learning, includes them in the sample weights along with the phenotype $$Y$$. Both categories are penalized regression approaches to which we apply a stability selection procedure (Meinshausen and Bühlmann 2010) for support estimation.
## Modified outcome
In modified outcome, we substitute $$A$$ with $$\underline{A}$$ to rewrite $$\delta(X)$$ in the following way: $\delta(X) = \mathbb{E} \left[Y\left(\frac{\underline{A}}{\pi(\underline{A}=1\lvert X)} - \frac{1 - \underline{A}}{\pi(\underline{A}=0\lvert X)}\right)\Bigg\lvert X\right]$
Let $$\underline{Y}$$ denote the modified outcome: $\underline{Y} = Y\left(\frac{\underline{A}}{\pi(\underline{A}=1\lvert X)} - \frac{1 - \underline{A}}{\pi(\underline{A}=0\lvert X)}\right)$
The risk difference term $$\delta(X)$$ is then simplified to: $\delta(X) = \frac{1}{2}\mathbb{E}\left[\underline{Y}\lvert X\right]$
We can then recover the support of $$\delta(X)$$ by applying a model selection procedure to the penalized regression problem where the sample covariates are $$X$$ and the outcome is $$\underline{Y}$$. However, in case of misspecification of the propensity score, modified outcome may suffer from numerical instability. We therefore propose three extensions to help mitigate this effect. The first extension, shifted modified outcome, consists in the addition of a regularization term $$\xi$$ to the inverses of the propensity scores i.e. $$1/(\pi(A\lvert X) + \xi)$$. The second proposition, normalized modified outcome, respectively normalizes $$\underline{A}/\pi(\underline{A} = 1\lvert X)$$ and $$(1-\underline{A})/\pi(\underline{A} = 0\lvert X)$$ by their sums, $$\sum_{i=1}^{n} \dfrac{\underline{A}^{(i)}}{\pi(\underline{A}^{(i)} = 1\lvert X^{(i)})}$$ and $$\sum_{i=1}^{n} \dfrac{1-\underline{A}^{(i)}}{\pi(\underline{A}^{(i)} = 0\lvert X^{(i)})}$$. The last but certainly not least proposition is robust modified outcome (see Slim et al. 2018; also Lunceford and Davidian 2004). In extensive simulations (Slim et al. 2018), it outperformed not only the other approaches within the modified outcome family, but also BOOST (Wan et al. 2010), a state-of-the-art method for epistasis detection.
## Outcome weighted learning
In outcome weighted learning, instead of the estimation of the difference of $$\mathbb{E}(Y\lvert A = +1, X)$$ and $$\mathbb{E}(Y\lvert A = -1, X)$$, we predict their $$\log$$-ratio:
$d(X) = \ln \frac{\mathbb{E}(Y\lvert A = +1, X)}{\mathbb{E}(Y\lvert A = +1, X)}$
The verification of $$\text{sign}\; \delta(X) = \text{sign}\; d(X)$$ is straightforward. This makes outcome weighted learning a relaxation of modified outcome. However, the regression models are completely unrelated. Outcome weighted learning is a weighted binary classification problem where the sample weights are $$Y/\pi(A\lvert X)$$, the outcome is the target $$A$$ and the covariates remain $$X$$. Without regularization, the use of the inverses of propensity scores can also result in numerical instability.
## Case study
Now that we have exposed the theoretical grounds of our methods, we explain how to use them in practice for epistasis detection. For that purpose, we illustrate their usage on a synthetic dataset included with this package. Using HAPGEN2 (Su, Marchini, and Donnelly 2011), we simulated $$450$$ SNPs on the $$22^{nd}$$ chromosome between the nucleotide positions $$16061016$$ and $$19976834$$ in the GRCh37 coordinates. The prior QC steps to control for rare variants ($$\text{MAF} < 0.01$$) and Hardy–Weinberg equilibrium ($$p < 10^{-6}$$) have already been performed. The simulated genotypes are saved as an integer matrix. We also included their minor allele frequencies (MAFs).
The first step in the pipeline is to load the genotypes matrix and the SNP MAFs vector.
require("epiGWAS")
data(genotypes)
data(maf)
### Linkage disequilibrium around the target
To alleviate issues of linkage disequilibrium around the target $$A$$ and avoid overfitting in the estimation of the propensity scores $$\pi(A\lvert X)$$, we remove all SNPs within a certain window of $$A$$. On each side of the target, the width of the window is of three clusters. The clusters are the result of an unsupervised clustering procedure such as hierarchical clustering. Compared to fixed-size windows, such dynamic windows allow to better account for genetic architecture.
set.seed(347)
sigma <- cor(genotypes)
sigma_distance <- as.dist(1 - abs(sigma))
hc <- hclust(sigma_distance, method = "single")
corr_max <- 0.5
clusters <- cutree(hc, h = 1 - corr_max)
### Genotype construction
After the clustering procedure, we can sample the causal SNPs. Beside the target, the other causal variants are sampled outside of the LD window. In total, we sample $$80$$ SNPs that interact with the target, $$20$$ SNPs with marginal effects and $$20$$ additional SNP pairs with epistatic effects. Moreover, among the $$80$$ synergistic SNPs, $$10$$ also have separate marginal effects and another $$5$$ have additional epistatic effects (with another SNP than the target). The sample_SNP function samples at most one causal SNP per cluster to avoid duplication of effects. Despite the high number of SNPs selected to be causal, the problem is still imbalanced with $$80$$ out of $$414$$ SNPs being causal.
# Parameterization of the disease model
window_target <- 3 # Width of the LD window on each side of the target
nX <- 80 # Number of SNPs interacting with the target
nY <- 20 # Number of SNPs with marginal effects
nZ12 <- 20 # Number of SNP pairs with epistatic effects
overlap_marg <- 10 # Number of SNPs interacting with the target in addition to having marginal effects
overlap_inter <- 5 # Number of SNPs interacting with the target in addition to having epistatic effects
set.seed(347)
causal <- sample_SNP(
nX, nY, nZ12,
clusters, maf, thresh_MAF = 0.01,
window_size = window_target, overlap_marg = overlap_marg, overlap_inter = overlap_inter
)
clusters <- merge_cluster(clusters, center = clusters[causal$target], k = window_target) Finally, we only retain the target from all SNPs in its surrounding LD window: genotypes <- genotypes[, (clusters != clusters[causal$target]) | (colnames(genotypes) == causal$target)] ### Phenotype simulation The phenotypes are simulated according to a logistic model in which the effect sizes are sampled from a normal distribution of mean $$0$$ and standard deviation $$1$$. set.seed(347) model <- gen_model(nX, nY, nZ12, mean = rep(0, 4), sd = rep(1, 4)) # Sampling of size effects phenotype <- sim_phenotype(genotypes, causal, model) # Phenotype simulation ### Epistasis detection As the fastPHASE software cannot be included with this package, we directly provide the propensity scores vector. The results can be reproduced by running fast_HMM with the dimensionality of the latent space n_state = 10 and the number of iterations for the EM algorithm n_iter = 20. Before applying our epistasis detection methods, we separate the target $$A$$ from the rest of the genotype, denoted here by $$X$$: data("propensity") A <- genotypes[, causal$target] > 0
X <- genotypes[, colnames(genotypes) != causal\$target]
We now run all methods with their default settings, which generally offers a good trade-off between speed and inference performance
stability_scores <- epiGWAS(A, X, phenotype, propensity,
methods = c("OWL", "modified_outcome", "shifted_outcome",
"normalized_outcome", "robust_outcome"),
parallel = FALSE)
The last step is to evaluate the epistasis detection performance in terms of the areas under the receiver operating characteristic (ROC) and precision/recall (PR) curves.
Areas under the ROC and PR curves
Method ROC PRC
Modified outcome 0.7010269 0.3399078
Normalized modified outcome 0.6680241 0.3237371
OWL 0.5243626 0.1959425
Robust modified outcome 0.6432897 0.2944554
Shifted modified outcome 0.6751771 0.3079225
The results are perfectly concordant with our findings in (Slim et al. 2018). Among the five methods, robust modified outcome is obviously the best performer in terms of areas under both the ROC and the PR curves.
## References
Lunceford, Jared K., and Marie Davidian. 2004. “Stratification and weighting via the propensity score in estimation of causal treatment effects: A comparative study.” Statistics in Medicine 23 (19): 2937–60. https://doi.org/10.1002/sim.1903.
Meinshausen, Nicolai, and Peter Bühlmann. 2010. “Stability selection.” Journal of the Royal Statistical Society: Series B (Statistical Methodology) 72 (4): 417–73. https://doi.org/10.1111/j.1467-9868.2010.00740.x.
Rosenbaum, Paul R, and Donald B Rubin. 1983. “The Central Role of the Propensity Score in Observational Studies for Causal Effects.” Biometrika 70 (1): 41–55.
Slim, Lotfi, Clément Chatelain, Chloé-Agathe Azencott, and Jean-Philippe Vert. 2018. “Novel Methods for Epistasis Detection in Genome-Wide Association Studies.” bioRxiv, January. http://biorxiv.org/content/early/2018/10/14/442749.
Su, Zhan, Jonathan Marchini, and Peter Donnelly. 2011. “HAPGEN2: Simulation of Multiple Disease SNPs.” Bioinformatics 27 (16): 2304–5. https://doi.org/10.1093/bioinformatics/btr341.
Wan, Xiang, Can Yang, Qiang Yang, Hong Xue, Xiaodan Fan, Nelson L. S. Tang, and Weichuan Yu. 2010. “BOOST: A Fast Approach to Detecting Gene-Gene Interactions in Genome-Wide Case-Control Studies.” The American Journal of Human Genetics 87 (3): 325–40. https://doi.org/10.1016/j.ajhg.2010.07.021.
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https://mathoverflow.net/users/38468/lev-borisov?tab=topactivity
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Lev Borisov
33 Advice for pure-math Phd students 32 The sum of squared logarithms conjecture 17 Interesting examples of vacuous / void entities 15 Die hard nilpotent spaces 10 Eigenvalues of a matrix with entries involving combinatorics
### Reputation (4,796)
+10 Crepant resolutions of toric varieties +10 What is the meaning of $(h^{11},h^{21})\to (h^{11}-240,h^{21}+240)$ in Calabi-Yau threefolds? +10 which varieties can appear as exceptional divisors? +10 Proof for a Rank-One Decomposition Theorem of Positive (semi) Definite Matrices
### Questions (27)
36 What is the meaning of $(h^{11},h^{21})\to (h^{11}-240,h^{21}+240)$ in Calabi-Yau threefolds? 24 Real square roots of symmetric matrices 15 Derived categories of arithmetic schemes? 11 What is Koszul dual of a curve? 11 Determinant and eigenvalues of a specific matrix
### Tags (112)
69 ag.algebraic-geometry × 35 32 symmetric-polynomials 51 polynomials × 6 32 matrix-theory 35 matrices × 7 29 co.combinatorics × 9 33 reference-request × 9 27 linear-algebra × 7 32 inequalities 22 convex-polytopes × 6
### Bookmarks (25)
64 A bestiary of topologies on Sch 57 “Gross-Zagier” formulae outside of number theory 39 The sequence $a_{n+1}=\left\lceil \frac{-1+\sqrt{5}}{2}a_{n}-a_{n-1} \right\rceil$ is periodic 38 The sum of squared logarithms conjecture 37 Is there a finite family of functions such that the max of any two functions can be dominated by a third?
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https://www.physicsforums.com/threads/3-dimension-expectation-values-qm.145495/
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# 3-Dimension Expectation Values (QM)
1. Nov 26, 2006
### moo5003
Hello, I have a problem that wants me to find the expectation value of <r> <r^2> for the ground state of hydrogen (part a.). My friend and I already completed the exercise but i'm concerned about how we found the expectation value. Since the ground state of hydrogen is only dependent on r do we only integrate over r? I notice that if we integrate over psi and phi we will add an extra 2pi^2 multiplied with what we had previously. Any help would be appreciated:
Recap- Do you integrate over all three dimensions if the wave function is only dependent on one?
2. Nov 26, 2006
### OlderDan
You need to make sure the wave functions are normalized and that you are accounting for the variation of spatial volume in the vecinity of any given r. If you are using the full wave function with its normalization constant then you need the angular integrals to get the normalization correct. There are also factors of r in the volume element dV that are important. People often look at the function u(r) = rR(r) as a better representation of the radial wave function because the amount of 3-D space associated with any given dr is proportional to r². This all comes together naturally if you use the full normalized wave function integrated over all space.
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https://www.theguardian.com/sustainable-business/2015/may/28/switching-to-biofuels-would-place-unsustainable-demands-on-water-use
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# Switching to biofuels could place unsustainable demands on water use
Transition away from fossil fuels is underway, but without assessing demands on land and water resources we put the future health of our planet at risk
# Switching to biofuels could place unsustainable demands on water use
Transition away from fossil fuels is underway, but without assessing demands on land and water resources we put the future health of our planet at risk
As the world moves towards renewable sources of energy, it faces an accompanying challenge: water scarcity. The intensive water use in the coal, oil, gas and nuclear industries is well-documented, but if we want to encourage a faster transition to renewables we must also contemplate the water use of the alternatives.
It is a great challenge to limit the drain on land and water resources now the transition has taken off. Bioenergy, hydropower, and wind, solar and geothermal energy all require substantial amounts of land and water resources. Given limitations to the availability of land and water, what energy scenarios are feasible in the long run?
With fossil fuels we have learned to worry about energy scarcity as a major concern for economic development and national security. In contrast, renewable energy seems inexhaustible: incoming solar radiation, for example, is far beyond what we need. The fact that renewable energy is available into infinity reinforces this idea of limitlessness. This, however, is a misunderstanding: we will replace energy scarcity by land and water scarcity.
## Biofuels
Bioenergy production in particular requires vast amounts of land and water. Besides, with current energy-intensive agricultural practices, net energy output is far lower than gross energy production, sometimes even near zero. If only 10% of fossil fuels in the global transport sector were replaced by bioethanol from relatively efficient crops, global water demand would increase by 6-7%.
The production of biofuels at the rate we are used to consuming fossil fuels will require more land and water than sustainably available. Already today we have land and water footprints beyond maximum sustainable levels and bioenergy increasingly competing with food.
## Hydropower and the dam debate
Hydropower, accounting for 16% of the world’s electricity supply, is regarded as a clean form of energy. However, we cannot simply increase hydroelectric capacity. Dams can heavily impact on riparian ecosystems and societies, and any further damming of rivers should be subject to careful consideration.
Building new dams and reservoirs is often difficult because the required land is generally already in use for other purposes. For the Three Gorges Dam in China, over one million people were displaced. Besides, hydropower can be a large water consumer because of the additional evaporation from the reservoir created, which affects downstream water availability for other purposes. Damming rivers has therefore become a contentious topic.
## Solar, wind and geothermal energy
Per unit of energy, the water footprint of bioenergy and hydroelectricity is two to three orders of magnitude larger than that of fossil fuels and nuclear. The water footprint of photovoltaic (PV) and wind energy is one to two orders of magnitude smaller.
Electricity from concentrated solar power has a similar water footprint to fossil fuels, while geothermal can be an order of magnitude smaller or even less. From a water consumption and scarcity perspective, it matters greatly whether we shift from fossil energy to bio and hydro or to solar, wind and geothermal energy.
All existing “green” energy scenarios, called “green” because of their considerable fractions of renewable energy, are based on considerable growth of bio and hydro in the mix, which means that the water footprint of the energy sector will grow sky-high if we follow such scenarios. True green scenarios, with a declining rather than increasing water footprint, must be primarily based on solar, wind and geothermal energy.
## The transition to electricity
Solar energy is more efficient than biomass from a land use perspective because PV panels and concentrated solar power systems are more efficient at capturing incoming solar radiation than photosynthesis, thus generating more energy per square metre.
Photosynthesis, however, has the advantage that it results in storable bioenergy and can be turned into energy-dense biofuels, while PV results in non-storable electricity. Concentrated solar power systems can store energy by use of thermal energy storage, but the final product will still be electricity, not fuel.
Since substantial growth of bioenergy – beyond using rest streams of organic material – is impossible, our economies need to be further electrified: electric transport, but also electric heating, at least where surplus heat from industrial processes or geothermal energy doesn’t offer a solution. We need to find ways to store energy and design electrical grids that can handle the large variability of both electricity demand and supply.
Solar and wind power and earth’s heat offer possibilities to achieve energy self-sufficiency at much smaller scales than we are used to in our globalised fossil fuel economy. The time is ripe for a transition away from fossil fuels. Let’s be smart enough to invest in real sustainable solutions, which excludes biofuels that have been so much at the centre of attention in government policies. Decarbonising our economy can be combined with lowering our water footprint, let’s go for that choice.
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https://www.mail-archive.com/search?l=ntg-context%40ntg.nl&q=from:%22Willi+Egger%22&o=newest&f=1
|
Hans,
I was looking trough your new manuals. Chapeau! Very interesting and good
reading! — I wonder whether your day still has 24 hours ;-) — Thank you so much!
Willi
> On 17 Nov 2020, at 12:55, Hans Hagen wrote:
>
> Hi,
>
> I uploaded a new version of lmtx (and mkiv). We're still in the process of
> migrating code from mkiv to lmtx (using new features). Anyway, I also
> uploaded a few more (preliminary) 'manuals'
>
>
> but some is work in progress. It shows a bit how things evolve(d) and what ws
> and i are dealing with now. More (details) in due time.
>
> Hans
>
> -
> Hans Hagen | PRAGMA ADE
> Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
> tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> -
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### Re: [NTG-context] How to reproduce a particular head/title style (reformat)
Hi Garulfo!
Now! — You managed do do a nice job! :-)
Willi
> On 15 Nov 2020, at 19:53, Garulfo wrote:
>
> Hi,
>
> finally I made some progress and uploaded files to the wiki in "Reports and
> articles" Samples section (https://wiki.contextgarden.net/Sample_documents)
>
> Initial PDF document:
>>
>
> ConTeXt output :
>> https://wiki.contextgarden.net/images/4/45/2020_hcc_rapport_maitriser-l-empreinte-carbone-de-la-france.pdf
>
> ConTeXt input files (build with pdftotext > markdown > pandoc > manual work
> and inkscape):
>> https://wiki.contextgarden.net/images/4/45/2020_hcc_rapport_maitriser-l-empreinte-carbone-de-la-france.pdf
>
> Any feedback is welcome (even if source code is not really clean)
>
> I learned a lot, and I definitely recommend such an exercise for document
> design with ConTeXt :
> - take a PDF file with a design you appreciate
> - extract the content
> - try to reproduce the design with ConTeXt
>
>
>
>> I would like to learn "how to ConTeXt" complex titles styles like the one
>> seen in the following document:
>> - https://wiki.contextgarden.net/images/f/f1/Screenshot_20201103_220818.png
>> - source document:
>> 1. doublesided document
>> 2. on both side, section title are underlined by a red rule, always "left
>> aligned" in the text area, shifted to the right by the same distance than it
>> is done for the text of the title, which ends at the right border of the page
>> 3. on the left page : section title are overlined by a "second red rule",
>> which starts "left aligned" in the text area, and goes across the whole page
>> width
>> 4. on the right page : the "second red rule" starts from the left border of
>> the page, and terminates at the end of the text area
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### Re: [NTG-context] Filler rules
Thank you Wolfgang! — In the meantime i was indeed able to setup what i needed
with \blackrule
Kind regards
Willi
> On 22 Oct 2020, at 22:09, Wolfgang Schuster
> wrote:
>
> Willi Egger schrieb am 15.10.2020 um 21:59:
>> Hoi,
>>
>> In earlier times we had something like \definerule[…][…] and
>> \setuprule[…][…]. This made it possible to create lines of a define width.
>
> I'm sorry but I'm unable to find any code or proper example for the command.
>
>> So what I found is the fillers, which apparently are not meant for the
>> purpose I am looking for.
>
> You can try the \blackrule command to add a custom rule after your title.
>
> Wolfgang
>
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### Re: [NTG-context] A Spanish introduction to ConTeXt Mark IV
Good evening Joaquin,
first of all congratulations for your initiative, this is really an impressive
piece of work!
Without wanting to critisize I think, that in general MKIV documents should be
made up with \start”elment” … \stop”element”. This will be important for all
those, who also need to produce xml.
I encountred two things in your book:
page 96 at the bottom. You write that the “height” is header + headerdistance +
textheight + bottomdistance + bottom. This should be footerdistance and footer.
— The graphic showing the areas however is correct.
page 139 at the top: \chapter[title=…,reference=..]. This should be
\startchapter[title=…,reference=…] … \stopchapter
Again, thank you for all your work! — Sorry “no hablo Espaniol”…
Saludos cordiales
Willi
> On 14 Oct 2020, at 06:27, Joaquín Ataz López wrote:
>
> Sorry. By mistake I sent the message as a reply to another one, when in fact
> I was trying to start a new thread with it. I'm sending it again (I think
> I'll do it right now):
>
> -
>
> Good morning to everyone.
>
> Although I guess it will not be of interest to most of the list members, I
> wanted to communicate that I have written an introduction to ConTeXt Mark IV
> https://webs.um.es/jal/docs/introCTX.pdf. Its title is "An Introduction (not
> too short) to ConTeXt Mark IV".
>
> ConTeXt is a wonderful document composition system, but there is not much
> literature to help you get into it, hence my initiative. The problem is that
> I've only been using ConTeXt for a short time and still have many doubts, so
> it's possible that the introduction may contain errors. As it has been
> written in Spanish I don't think many of you will be able to read it, but I
> would appreciate, of course, any suggestions for improvement. The document
> is, on the other hand, free and anyone who wants to include it in any ConTeXt
> distribution can, of course, do so. Also, if anyone wants the source files, I
> have no problem providing them.
>
> I have not based my introduction on LMTX because I think that for beginners a
> more stable system, like LuaTeX, is preferable.
>
> Finally, I apologize for my bad English level. I read it reasonably well, but
> expressing myself in it is much harder for me.
>
> --
> Joaquín Ataz López
> Derecho Civil
>
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### Re: [NTG-context] Filler rules
Hoi,
In earlier times we had something like \definerule[…][…] and \setuprule[…][…].
This made it possible to create lines of a define width. — So what I found is
the fillers, which apparently are not meant for the purpose I am looking for.
Kind regards
Willi
> On 14 Oct 2020, at 16:33, Wolfgang Schuster
> wrote:
>
> Willi Egger schrieb am 14.10.2020 um 15:48:
>> Good afternoon!
>>
>> I am dealing with a book, which has a short black rule under the title of
>> the chapters.
>>
>> I see, that the old rule mechanisms are no more available in LMTX and are
>> replaced by fillers.
>
> What mechanism do you mean, fillers are just a high level interface to
>
> Wolfgang
>
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### [NTG-context] Filler rules
Good afternoon!
I am dealing with a book, which has a short black rule under the title of the
chapters.
I see, that the old rule mechanisms are no more available in LMTX and are
replaced by fillers.
Now with the following setup, I would expect a 50mm line placed centered.
Hoewever this seems not to work in this way.
What am I missing?
kind regards
Willi
\definefiller
[Titlerule]
[alternative=rule,
left=\hfil,
right=\hfil,
method=local,
width=50mm,
height=2pt,
leftmargin=1pt,
rightmargin=1pt,
align=middle]
\starttext
\midaligned{Some text}
\filler[Titlerule]
\stoptext
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### Re: [NTG-context] help with forced page break in TOC
Hello Julian,
the mechanism does not work in the typesetting of the TOC.
Whatt you is the following, when the book is in a final stage:
run the file with \showinjector. This will give you in the left margin the
numbers of the different TOC-entries.
Now you can say
\setinjector[list] [“the number of the injector where the break must take
place][\page]
I hope that this is solving your issue.
Kind regards
Willi
> On 5 Oct 2020, at 04:53, jbf wrote:
>
> I am unable to adapt the example given in
> https://wiki.contextgarden.net/Table_of_Contents#Forced_Page_Break to my
> situation:
>
> In my case, the ToC has no chapters per se, but uses a defined \mytitle. This
> produces a series of unnumbered items in the ToC.
>
> The example in contextgarden tells me to first define the break, which I have
> done:
>
> \definelistextra[page][before=\page]
> It then tells me to call this in where I \placecontent (in my case I am using
> my own defined \placecombined list[content]). The example given in the wiki
> is:
>
> \placecontent[extras={6=page}]
> But I have unnumbered items which are titles (mytitles), so I am not sure
> what to replace '6' with. I tried:
>
> \placecombinedlist[content][extras={mytitle title={Elements of
> Reading}=page}] since 'Elements of reading' is the title before which I want
> the page break to occur. This does not work. I tried variation of it, e.g.
> since it is the third such title I tried ][extras={3=page}] but that does
> nothing either.
>
> Any clues as to how I can resolve this small problem?
>
> Julian
>
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### Re: [NTG-context] VisualStudioCode on Linux
Hi Mikael,
Indeed it works!
Kind regards
Willi
> On 25 Sep 2020, at 07:50, Mikael Sundqvist wrote:
>
> Hi,
>
> I got help from the list, and in the end I did the following (I have ConTeXt
> installed in $HOME/ConTeXt-lmtx/). I hope it is complete. > > ln -s >$HOME/ConTeXt-lmtx/tex/texmf-context/context/data/vscode/extensions/context
> $HOME/.vscode/extensions/ > > Then I added a task file (also essentially found here, I think): > > %%% Begin of file$HOME/.config/Code/User/tasks.json
> {
> "name" : "context",
>{
>"label": "ConTeXt LuaMetaTeX",
>"type": "shell",
>"command": "export
> PATH=$HOME/ConTeXt-lmtx/tex/texmf-linux-64/bin/:$PATH;mtxrun --autogenerate
> --script context '${file}'", >"args": [], >"options": { >"cwd": "${fileDirname}"
>},
>"group": {
>"kind": "build",
>"isDefault": true
>},
>"problemMatcher": []
>}
> ]
> }
> %%% End of file
>
> Then, in the extension setting inside code, I had to enable the color scheme
> for context.
>
> Then it works to compile with ctrl+shift+B.
>
> /Mikael
>
> PS I also have some add-on for LaTeX installed, and for that reason I have
> started to use the file extension .mkiv for ConTeXt. Then the add-ons don't
> clash.
>
> On Thu, Sep 24, 2020 at 11:30 PM Willi Egger wrote:
> Hello Linux users!
>
> Can somebody tell me how to get the extension for ConTeXt to be installed for
> VisualStudioCode?
>
> Kind regards
>
> Willi
>
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### [NTG-context] VisualStudioCode on Linux
Hello Linux users!
Can somebody tell me how to get the extension for ConTeXt to be installed for
VisualStudioCode?
Kind regards
Willi
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### Re: [NTG-context] \checkpage in the TOC
Beste Hans!
thank you so much for your solution!
Kind regards
Willi
> On 12 Aug 2020, at 02:04, Hans Hagen wrote:
>
> On 8/10/2020 11:02 PM, Willi Egger wrote:
>> Hello!
>> humble, in another book I am trying to improve the list of contents. On
>> different places occur page breaks which should be addressed and corrected.
>> I tried to use the method \checkpage[][], however my attempts are not
>> succesful.
>> For your reference I include a screenshot of the problematic pagebreak.
>> \definepagechecker
>> [willi]
>> [method=1,before=,after=,inbetween={\page}]
>> \setuplist
>> [chapter]
>> [prefix=no,
>> sectionnumber=no,
>> alternative=command,
>> command=\Mychaptercommand,
>> inbetween={\checkpage[willi][lines=4]}
>> Kind regards
>> Willi
>> ]
> Here's an example of an actually already quite old mechanism ..
>
> \showinjector
>
> \setinjector[register][3][\column]
> \setinjector[list][2][{\blank[3*big]}]
>
> \starttext
> \placelist[section][criterium=text]
> \blank[3*big]
> \placeregister[index][criterium=text]
> \page
> \startsection[title=Alpha] first \index{first} \stopsection
> \startsection[title=Beta] second \index{second} \stopsection
> \startsection[title=Gamma] third \index{third} \stopsection
> \startsection[title=Delta] fourth \index{fourth} \stopsection
> \stoptext
>
> .. so you now have something to wikify ..
>
> Hans
>
> -
> Hans Hagen | PRAGMA ADE
> Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
> tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> -
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### [NTG-context] \checkpage in the TOC
Hello!
humble, in another book I am trying to improve the list of contents. On
different places occur page breaks which should be addressed and corrected.
I tried to use the method \checkpage[][], however my attempts are not succesful.
For your reference I include a screenshot of the problematic pagebreak.
\definepagechecker
[willi]
[method=1,before=,after=,inbetween={\page}]
\setuplist
[chapter]
[prefix=no,
sectionnumber=no,
alternative=command,
command=\Mychaptercommand,
inbetween={\checkpage[willi][lines=4]}
Kind regards
Willi
]___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### [NTG-context] Header bottom line vanishing after 87 pages
Hello good morning,
I encounter a strange problem when compiling my project. The book has 252
pages, compilation runs without errors. But after 87 pages the bottom frame of
the header is turned off. The \setupbackgrounds command is given only once in
the preamble. — So I am curious what that can be.
I tried to reproduce the problem by a simple 255 page loop, but there the issue
does not appear.
There is no difference between MKIV and LMTX, no difference in older version
and yesteray evening’s version of ConTeXt.
My question is whether anybody has an idea how to track down this issue.
Kind regards
Willi
___
Wiki!
maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___
### Re: [NTG-context] Placing a section ending depending on odd/even sectionnumber
Wolfgang, thank you so much for your help!
Hm, when reading your explanation I start to understand my short cut in
I will build it into my project…
Thanks and kind regards
Willi
> On 4 Aug 2020, at 19:46, Wolfgang Schuster
> wrote:
>
> Willi Egger schrieb am 04.08.2020 um 18:56:
>> Hi,
>> now I have another hurdle to be taken :-) — Depending on the odd or even
>> number of the section I have to place an ornament at the end of the section.
>> I have sofar the following setup:
>> [...]
>> However the the evaluation of the sectionnumber results always in “false”,
>> having therefore always odd as a sectionending.
>
> You have two problem:
>
> 1. To get the current value for \currentheadnumber you have use
> \determineheadnumber[section] before you use it but the example below shows a
> better method.
>
> 2. What you do with \doifelse{...}{even} is to compare the numeric value of
> the section with the string "even" which is always false. To check whether
> the value is odd or even you have to use the \ifodd command.
>
>> What to change in order to get the desired result?
>
> begin example
> \startsetups [section:odd]
> \vfill
> \bold {End of odd numbered section}
> \stopsetups
>
> \startsetups [section:even]
> \vfill
> \bold {End of even numbered section}
> \stopsetups
>
> \startsetups [section:end]
> \directsetup{section:odd}
> \else
> \directsetup{section:even}
> \fi
> \stopsetups
>
> [section]
> [aftersection=\directsetup{section:end}]
>
> \starttext
>
> \startsection[title=Ward]
> \input ward
> \stopsection
>
> \page
>
> \startsection[title=Knuth]
> \input knuth
> \stopsection
>
> \stoptext
> end example
>
> Wolfgang
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
> ___
___
Wiki!
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wiki : http://contextgarden.net
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### [NTG-context] Placing a section ending depending on odd/even sectionnumber
Hi,
now I have another hurdle to be taken :-) — Depending on the odd or even number
of the section I have to place an ornament at the end of the section.
I have sofar the following setup:
\define\stopmysection
{\setups{endsection}}
\startsetups endsection
\doifelse
{even}
{\vfil
{\bf End of even numbered section}
\stopsection%
}
{\vfil
{\bf End of odd numbered section}
\stopsection%
}
\stopsetups
\starttext
\startsection[title=Ward]
\setuppagenumbering[conversion=romannumerals]
\input ward
\stopmysection
\startsection[title=Knuth]
\setuppagenumbering[conversion=numbers]
\input knuth
\stopmysection
\stoptext
However the the evaluation of the sectionnumber results always in “false”,
having therefore always odd as a sectionending.
What to change in order to get the desired result?
Kind regards
Willi
___
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### Re: [NTG-context] About testing rest of space on a page
Hello Taco and Wolfgang!
Thank you both for the reply and input. — I am going to play :-)
Kind regards
Willi
> On 30 Jul 2020, at 21:25, Wolfgang Schuster
> wrote:
>
> Taco Hoekwater schrieb am 30.07.2020 um 09:05:
>>> On 29 Jul 2020, at 23:08, Willi Egger wrote:
>>>
>>> Good evening!
>>>
>>> I have a bookproject in which sections are ended with a small graphical
>>> element. Now as usual this graphic might be moved to a new page which is of
>>> course unwanted.
>>>
>>> At this moment I have:
>>>
>>> \startsetups endsection
>>> \vfil
>>> \placefigure[middle,none][]{}{\externalfigure[ornament2][height=2\lineheight]}
>>> \stopsection
>>> \stopsetups
>>>
>>> \def\stopmysection{\setups{endsection}}
>>>
>>> I use then instead of \stopsection the \stopmysection. This works except
>>> that the ornament is in some cases placed on the next page. — My question
>>> is whether it is possible to do a \testpage and evaluate the result hereof
>>> and then using either the placement of the ornament and stop the section or
>>> just end the section without ornament?
>> You can put your setups *inside* the test:
>>
>> \definepagechecker
>>[willi]
>>[method=1,before=,after=,inbetween={\setups{endsection}}]
>>
>> \def\stopmysection
>>{\checkpage[willi][lines=4]}
>>
>> The before=/after= pair is used when a page break is forced by the test,
>> inbetween= is used if there is no forced break.
>>
>> (\testpage is a wrapper around \checkpage:
>> https://source.contextgarden.net/page-brk.mkiv?search=testpage#l564 )
>
> No need for a new \stop command.
>
> [section]
> [aftersection={\checkpage[willi][lines=4]}]
>
> Wolfgang
>
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### [NTG-context] About testing rest of space on a page
Good evening!
I have a bookproject in which sections are ended with a small graphical
element. Now as usual this graphic might be moved to a new page which is of
course unwanted.
At this moment I have:
\startsetups endsection
\vfil
\placefigure[middle,none][]{}{\externalfigure[ornament2][height=2\lineheight]}
\stopsection
\stopsetups
\def\stopmysection{\setups{endsection}}
I use then instead of \stopsection the \stopmysection. This works except that
the ornament is in some cases placed on the next page. — My question is whether
it is possible to do a \testpage and evaluate the result hereof and then using
either the placement of the ornament and stop the section or just end the
section without ornament?
Kind regards
Willi
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### [NTG-context] Pagenumbering with \setupcounter[userpagenumber]
Good evening!
I am trying to make use of the userpagenumber counter. I have a book at hand,
where I need to adjust the start of the pagenumbering.
It appears to me, that the \setupcounter[userpagenumber[state=stop] and later
the \setupcounter[userpagenumber][state=start,start=7] is not giving the
expected result.
MWE:
% Context file
\mainlanguage[en]
\usetypescript[termes]
\setupbodyfont[termes,9pt]
\setuppapersize [A5][A5]
\setuppagenumbering[location=,alternative=doublesided]
[text]
[]
[\userpagenumber]
[\userpagenumber]
[{\getmarking[chapter]}]
\setupfootertexts
[]
[\pagenumber]
[\pagenumber]
[]
\setupmakeup[standard][top=,bottom=,doublesided=yes]
\setupcounter[userpagenumber][state=stop]
\starttext
\startstandardmakeup[page=yes,doublesided=yes]
\strut
\godown[.2\textheight]
\rightaligned{Bramble-Bees}
\stopstandardmakeup
\startstandardmakeup[doublesided=yes,page=yes]
\strut
\godown[.1\textheight]
\startalignment[middle]
{\bfb BRAMBLE-BEES AND OTHER}
\blank[line]
{\bfa by J. HENRI FABRE}
\stopalignment
\vfill
\startalignment[middle]
{TRANSLATED BY ALEXANDER TEIXEIRA DE MATTOS, F.Z.S.}
\stopalignment
\stopstandardmakeup
\starttitle[title={TRANSLATOR'S NOTE.}]
\input ward
\stoptitle
\setupcounter[userpagenumber][state=start,number=7]
\starttitle[title=Contents]
\placelist[chapter]
\stoptitle
\startchapter[title=Ward]
\input ward
\stopchapter
\startchapter[title=Knuth]
\input knuth
\stopchapter
\stoptext
Is this a bug or do I miss something?
Kind regards
Willi
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### Re: [NTG-context] Using \defineoverlay for a framed text
Hi Marco,
thank you! :-)
Willi
> On 16 Jun 2020, at 14:44, Marco Patzer wrote:
>
> On Tue, 16 Jun 2020 14:37:17 +0200
> Marco Patzer wrote:
>
>> On Tue, 16 Jun 2020 14:17:09 +0200
>> Willi Egger wrote:
>>
>>> I try to use a Metapost drawing as a background to a framed text. —
>>> I can not make it working though…
>>>
>>> \startuniqueMPgraphic{Markings}
>>> %{Markings:\overlaywidth:\overlayheight} fill OverlayBox enlarged
>>> 5mm withcolor blue; \stopuniqueMPgraphic
>>>
>>> \defineoverlay[Marks]{\useMPgraphic{Markings}}
>>
>> \defineoverlay[Marks][{\useMPgraphic{Markings}}]
>
> Better:
>
> \defineoverlay[Marks][\useMPgraphic{Markings}]
>
> Marco
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### [NTG-context] Using \defineoverlay for a framed text
Hello listmembers,
I try to use a Metapost drawing as a background to a framed text. — I can not
make it working though…
\startuniqueMPgraphic{Markings} %{Markings:\overlaywidth:\overlayheight}
fill OverlayBox enlarged 5mm withcolor blue;
\stopuniqueMPgraphic
\defineoverlay[Marks]{\useMPgraphic{Markings}}
\setupframed[background=Marks]
\setupframedtexts
[frame=on,
background=Marks]
\starttext
\framedtext{Hello World!}
\blank
\framed{Hello World!}
\stoptext
What is wrong with this code?
Kind regards
Willi
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### Re: [NTG-context] ConTeXt source browser website update
This is really a nice interface! Thank you so much for all this work!
Willi
> On 7 Jun 2020, at 16:25, Taco Hoekwater wrote:
>
> Hi all,
>
> I just replaced the software of https://source.contextgarden.net/ by a Lua
> implementation that uses Hans Hagen’s SciTE lexers for syntax highlighting
> and a Lua-generated search index.
>
> There is no official documentation yet (because I may want to change some
> stuff still) but here is some relevant information:
>
> * The search field uses a Lua string pattern to match a single word (no
> multi-word search as of yet).
>
> See https://www.lua.org/manual/5.3/manual.html#6.4.1 for the syntax of lua
> string patterns.
>
> * The search index only contains 7-bit ASCII ‘words’ that contain at least
> one of 'a-zA-Z’ (writing an LPEG for unicode matching is a tricky and
> probably would be quite slow even if I could make it work).
>
> Still, this should be ok-ish because most of the ConTeXt source is ASCII,
> except for the interface files.
>
> * The files context-en.xml, mtxrun{.lua}, and all of the files in the
> tex/context/patterns subtree are skipped in the search index. Also skipped
> are words shorter than 3 bytes, lua keywords, and words having more than
> (approx) 1500 hits
>
> * On the plus side, because of the SciTE lexer, “contextversion’ and
> “\contextversion” are separate entries in the search index. And you can
> search for “\@@kldirection”.
>
> * For text file types that have no SciTE lexer there is no syntax
> highlighting, and binary files are ignored altogether.
>
> The rest of the interface should be self-explanatory.
>
> Suggestions for improvements are welcome.
>
>
> Index statistics:
>
> 4085 files processed, 178 skipped, 3744 with matches
> 120733 words found
> 119154 words exported to word.idx
> 37928 comment words found
> 36880 words exported to comment.idx
> 26756 documentation words found
> 26018 words exported to docs.idx
>
> The word.idx is roughly 11 megabytes.
>
> Have fun,
>
> Taco
>
>
>
>
> ___
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> Wiki!
>
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### Re: [NTG-context] macOS
If I understand the policy of Apple correctly, then it is that \usr is not
meant to be a directory to be used by the user and therefore spotlight by
default will not index anything in that directory. When opening Finder then the
mentioned folder is not even shown i.e. it is hidden and spotlight will
accordingly not index such directories.
Willi
> On 31 Mar 2020, at 10:44, Gerben Wierda wrote:
>
> I already had done all of that including command line versions like ‘sudo
> mdutil -E’
>
> It turns out macOS apparently excludes /usr (amongst other things) and I
> haven’t found a way to configure that. So, when ConTeXt is installed in
> /usr/local (which is pretty typical), SpotLight doesn’t find the manuals,
> whereas when it has been installed in — say — /Applications, it will find
> them.
>
> G
>
>> On 31 Mar 2020, at 06:21, janerik.hagglof wrote:
>>
>> Maybe this is the solution, haven't tried it myself.
>>
>> https://support.apple.com/en-us/HT201716
>>
>> Janne
>>
>>
>>
>> Med Vänlig Hälsning
>>
>> Jan-Erik Hägglöf
>>
>>
>> Originalmeddelande
>> Från: Gerben Wierda
>> Datum: 2020-03-30 23:52 (GMT+01:00)
>> Till: mailing list for ConTeXt users
>> Ämne: [NTG-context] macOS
>>
>> Spotlight on macOS can help me to find the right documentation.
>>
>> When I copy the contents of the folder (the manuals for ConTeXt) from its
>> original location
>> /usr/local/context-osx-64/tex/texmf-context/doc/context/documents/general/manuals
>>
>> But not in their original location. Why? And how do I fix this, because I
>> want the manuals and such in /usr/local to be found.
>>
>> Any Mac user who knows?
>>
>> G
>> ___
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>>
>> maillist : [email protected] /
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>> ___
>> the Wiki!
>>
>> maillist : [email protected] /
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>
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### Re: [NTG-context] Box of certain width (and height?) containing a paragraph of text?
Gerben,
did you think about using \framedtext, setting the frame off?
Willi
> On 30 Mar 2020, at 21:45, Gerben Wierda wrote:
>
> Does ConTeXt have a command to create a (non framed) box from a line of text,
> where the text is typeset as a paragraph inside a box of certain size?
>
> G
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### Re: [NTG-context] Problem with \setuparranging
When looking at your setup, then it appears, that you start arranging two
times. This is not how arranging works. — Context will first compile the whole
document as single pages and only after all is ok, it will loop over the pages
and arrange them. So it is not possible to mix e.g. A4 portrait pages with A3
landscape pages in an imposition run.
Willi
> On 13 Feb 2020, at 15:13, [email protected] wrote:
>
> Hello,
>
> I missed to write my code:
>
> \starttext
> \pagefigure[A3.pdf]
>
> \start
> \setuppapersize[A4,portrait][A3,landscape]
> \setuparranging[2SIDE]
>\pagefigure[A4.pdf]
>\input knuth
> \stop
>
> \pagefigure[A3.pdf]
>
> \start
> \setuppapersize[A4,portrait][A3,landscape]
> \setuparranging[2SIDE]
>\pagefigure[A4.pdf]
>\input knuth
> \stop
> \stoptext
>
> Any idea what I am doing wrong?
>
> Best regards,
>
> Lukas
>
> On 2020-02-13 10:38, [email protected] wrote:
>> Hello,
>> I need to create a document where page arranging is mixed somhow - so
>> that some pages are to be typeset "normally", some other placed "2
>> pages onto 1 page". All pages should appear as A3 size.
>> A simplified code follows; its goal is:
>> - page 1: to be one external figure of size A3 (red),
>> - page 2: to be composed of one page of size A4 (green) on the left
>> half, some text on the right half,
>> - page 3: to be one external figure of size A3 (the same as on page 1)
>> - page 4: to be composed of one page of size A4 on the left half, some
>> text on the right half (as on page 2).
>> The (unwanted) result is:
>> - page 1: as expected,
>> - page 2: as expected,
>> - page 3: surprisignly A4 (red) (whilst the figure is of A3),
>> - page 4: surprisingly A3, but some text on the left half, and no green A4.
>> Is \setuparranging limited somehow or intended for another use?
>> How to generate "Goal.pdf" instead of "t.pdf"?
>> Best regards,
>> Lukas
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### Re: [NTG-context] \setupitemgroup[itemize],/setupitemize
Wolfgang, thank you for this expalantion.
Kind regards
Willi
> On 18 Dec 2019, at 23:15, Wolfgang Schuster
> wrote:
>
> Willi Egger schrieb am 18.12.2019 um 19:58:
>> Wolfgans, Hraban,
>>
>> thank you very much for this instruction!
>>
>> - In the real itemlist I have of course \startitemize (sorry for the
>> ommission in the MWE
>> - I misinterpreted the Wiki. There is no mentioning in the red section that
>> n is possible. However the n in the green section must be used as the symbol
>> with n=123 or symbol=2.
>
> The n-key is used to set the number of columns when you set your items in
> multiple columns and it has the same effect as the two, three etc. keywords.
>
> The way how numbered items work is different. To change the symbol for the
> bullets or use numbers instead ConTeXt checks if the applies keywords include
> the name of a symbol (something you create with \definesymbol) or the name of
> a number conversion (something you create with \defineconversion) and applies
> it to the current entry.
>
> This check also you to create your own symbols or numbers orders by simply
> creating a new symbol and conversion.
>
> Wolfgang
>
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>
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### [NTG-context] \setupitemgroup[itemize],/setupitemize
Hello everybody,
I just wanted to typeset a simple file with a adaptet itemization. Howewer none
of the options have effect. Do I miss somehting or is itemize broken?
MWE:
% \setupitemize[packed][n,left={Step~},n]
\setupitemgroup[itemize][1][packed][left={Step~},n]
\starttext
\startitem
\stopitem
\startitem
Proceed with that\dots
\stopitem
\startitem
End with the following\dots
\stopitem
\stoptext
Kind regards
Willi
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### Re: [NTG-context] Cross referencing by using \useexternaldoument
Hello Wolfgang!
Thank you again for your explanation. Indeed the thing is the availability of
the tuc-file of the referenced file. — I will add a note on this on the Wiki.
Willi
> On 18 Aug 2019, at 18:07, Wolfgang Schuster
> wrote:
>
> Willi Egger schrieb am 18.08.2019 um 17:30:
>> Hi all,
>>
>> there is an old thread concerning this issue from september 2015. It appears
>> unfortunately, that this issue persists.
>>
>> You can reference to places inside a document, but references to an outside
>> document are broken. The links do not work and no page numbers or texts are
>> typeset from the external document.
>>
>> Can someone help me to solve this?
> I tried your example and had no problem to get the page and section numbers
> from the other document. What you have to ensure is that the tuc-file for the
> other document you want to refer dies exist because context uses it to get
> the values for the numbers etc.
>
> Wolfgang
>
> ___
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>
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### Re: [NTG-context] Cross referencing by using \useexternaldoument
Hello Wolfgang!
thank you so much for your quick reply! I will test and see!
Thanks!
Willi
> On 18 Aug 2019, at 18:07, Wolfgang Schuster
> wrote:
>
> Willi Egger schrieb am 18.08.2019 um 17:30:
>> Hi all,
>>
>> there is an old thread concerning this issue from september 2015. It appears
>> unfortunately, that this issue persists.
>>
>> You can reference to places inside a document, but references to an outside
>> document are broken. The links do not work and no page numbers or texts are
>> typeset from the external document.
>>
>> Can someone help me to solve this?
> I tried your example and had no problem to get the page and section numbers
> from the other document. What you have to ensure is that the tuc-file for the
> other document you want to refer dies exist because context uses it to get
> the values for the numbers etc.
>
> Wolfgang
>
> ___
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> Wiki!
>
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### [NTG-context] Cross referencing by using \useexternaldoument
Hi all,
there is an old thread concerning this issue from september 2015. It appears
unfortunately, that this issue persists.
You can reference to places inside a document, but references to an outside
document are broken. The links do not work and no page numbers or texts are
typeset from the external document.
Can someone help me to solve this?
Kind regards
Willi
MWE
File: one.tex
\enabletrackers[structures.referencing.analyzing]
\setupinteraction[state=start]
\starttext
\starttabulate[|l|l|l|]
\NC First document \NC \in{Chapter}[sec:first] \NC \at{Page}[sec:first]
\NC\NR
\NC Second document \NC \in{Chapter}[two::sec:second] \NC
\at{Page}[two::sec:second] \NC\NR
\stoptabulate
\dorecurse{3}{\page[empty]}
\chapter[sec:first]{First document}
\stoptext
File; two.tex
\enabletrackers[structures.referencing.analyzing]
\setupinteraction[state=start]
\starttext
\starttabulate[|l|l|l|]
\NC First document \NC \in{Chapter}[one::sec:first] \NC
\at{Page}[one::sec:first] \NC\NR
\NC Second document \NC \in{Chapter}[sec:second] \NC \at{Page}[sec:second]
\NC\NR
\stoptabulate
\dorecurse{2}{\page[empty]}
\chapter[sec:second]{Second document}
\stoptext
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### Re: [NTG-context] Typesetting hebrew in a table...
Hello Taco,
thank you so much. - Indeed this looks good! The option with
‘verytolerant,stretch’ works but does not look that nice, some words are really
far from each other…
So the way to go is “{r2l,right}”
Thanks!
Willi
> On 12 Aug 2019, at 15:36, Taco Hoekwater wrote:
>
>
>
>> On 12 Aug 2019, at 15:08, Willi Egger wrote:
>>
>> Hi all,
>>
>> my brother is studying Ifrith and wants to have a dictionary. The idea is to
>> typeset left German and right Ifrith in a /bTABLE…\eTABLE environment.
>>
>> When trying to typeset the Ifrith text is not broken into lines correctly
>> i.e. it is leaping into the cell reserved for the German text. — How to
>> correct this behaviour?
>
> Either use:
>
> \setupTABLE[column][2][align={r2l,right},width=42mm]
>
> or:
>
> \setupTABLE[column][2][align={r2l,verytolerant,stretch},width=42mm]
>
> since a bare ‘r2l’ is like “normal” except for the writing direction.
>
>
> Best wishes,
> Taco
>
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### [NTG-context] Typesetting hebrew in a table...
Hi all,
my brother is studying Ifrith and wants to have a dictionary. The idea is to
typeset left German and right Ifrith in a /bTABLE…\eTABLE environment.
When trying to typeset the Ifrith text is not broken into lines correctly i.e.
it is leaping into the cell reserved for the German text. — How to correct this
behaviour?
I attach a rather minimal sample.
Kind regards!
Willi
test-hebrew.tex
Description: Binary data
test-hebrew.pdf
test-paal.dat
Description: Binary data
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### Re: [NTG-context] Spacing after combination
Marco,
there is a \setupcombination command:
\setupcombination [...,...] [..,..=..,..]
1 NAME
2 nx
ny
width height location distance alternative align continue before after
inbetween style
color
OPT
= NUMBER
= NUMBER
= fit DIMENSION
= fit DIMENSION
= left middle right top bottom = DIMENSION
= label text
= inherits: \setupalign
= yes no
= COMMAND
= COMMAND
= COMMAND
= STYLE COMMAND
= COLOR
I hope this will enable you to get what you want.
Willi
> On 16 Jul 2019, at 17:08, Marco Patzer wrote:
>
> Hi!
>
> Is there a way to influence the spacing after a combination is
> placed?
>
> \useMPlibrary [dum]
>
> \starttext
>
> \startcombination [2*2]
> \startcontent \externalfigure \stopcontent
> \startcaption Foo\stopcaption
> \startcontent \externalfigure \stopcontent
> \startcaption Bar\stopcaption
> \startcontent \externalfigure \stopcontent
> \startcaption Lorem \stopcaption
> \startcontent \externalfigure \stopcontent
> \startcaption Ipsum \stopcaption
> \stopcombination
>
> \samplefile{knuth}
>
> \stoptext
>
> I know I could wrap it in a float and use the float to control the
> spacing, but it would be great if I could do without that float.
>
> Marco
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### Re: [NTG-context] aligning rotated text in a natural table
Martin, did you try to add [align=lohi]?
Willi
> On 12 Jun 2019, at 13:11, Martin Althoff wrote:
>
> I am trying to align rotated text horizontally and vertically in a table
> cell. Vertically
> is no problem, horizontally it fails. Non-rotated text is, of course, fine.
>
> What can I do to fix the problem? Thanks for suggestions.
>
> Martin
>
> using: mtx-context | current version: 2019.05.18 10:42
> PDF of my output is attached.
>
> MWE:
>
> \starttext
> \setupTABLE[c][1][width=7mm]
> \setupTABLE[c][2][width=30mm]
> \setupTABLE[r][each][align={lohi,middle},height= 50mm]
>
> \bTABLE
> \bTR
> \bTD \rotate[270]{\switchtobodyfont[8pt]a bit more text} \eTD
> \bTD blah \eTD
> \eTR
>
> \eTABLE
> \stoptext
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### Re: [NTG-context] https://wiki.contextgarden.net/Fraktur_fonts
Hi Rudolf,
I looked at your work on the wiki. It looks very nice, well-structured.
I wanted to try to upload the pictures. However if I understand the help
correctly, then one needs privileges to upload files?
Kind regards
Willi
> On 12 May 2019, at 19:56, Rudolf Bahr wrote:
>
> Hello All,
>
> I wrote the wiki page "https://wiki.contextgarden.net/Fraktur_fonts; on my
> experiences of ConTeXt and three Fraktur fonts.
>
> 4 result images are still missing. I didn't succeed in uploading them to the
> server in
> it for me?
> The 4 images are appended here.
>
> Best wishes,
>
> Rudolf___
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> Wiki!
>
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### Re: [NTG-context] How to write a wiki page?
Hello Rudolf,
the ConTeXt wiki kan be extended by everybody. What you should do is make your
account and then you can start.
which will be published in the next issue of the ConTexT journal. It is dealing
with the Maguntia font.
Kind regards
Willi
> On 24 Apr 2019, at 16:44, Rudolf Bahr wrote:
>
>
> Hello All!
>
> I'd like to write a wiki page on special Fraktur fonts, but I don't know how
> to begin
> technically. Are there rules? Certanly, but where? To whom would I send the
> result to
> correct it with respect to format, ConTeXt commands, English language,
> bringing it into
> the ConTeXt wiki and so on?
>
> Greetings,
>
> Rudolf
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>
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### [NTG-context] Manipulating the pagenumber in the TOC
Hi all,
"when manipulating in one area you will have to manipulate also in other aeras”
I must confess.
I asked some time ago about manipulating the pagenumber. Wolfgang provide me
the following approach:
\cldcontext{“\letterpercent.0f”,(\pagenumber+1)/2}
This works indeed fine. However now I am confronted with the fact, that in the
TOC the manipulated pagenumbers should be taken into account.
Wolfgang’s approach does not help and ends in an error:
TOC-pagenumber-test.tex
Description: Binary data
\define[1]\SectionTOCPagenumber{
\cldcontext{“\letterpercent.0f”,(\pagenumber+1)/2}}
\setuplist
[section]
[pagecommand=\SectionTOCPagenumber]
My question is: is there a way to manipulate the pagenumber in the TOC such,
that it reflects the pagenumbers in the document?
Kind regards
Willi___
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### Re: [NTG-context] Troubles with the \cldcontext command
Dear Wolfgang!
thank you so much for your reply. I tried the test file and it works. tomorrow
I will look further in a bigger environment.
Thanks and good night!
Willi
> On 2 Apr 2019, at 21:17, Willi Egger wrote:
>
> Hello!
>
> I have the following code, which should manipulate the page number. However I
> get an error:
>
>
> MWE:
>
> \setuppapersize [A6] [A6]
>
> \setuppagenumbering[location=none]
>
> \startsetups [Pagenumber]
> \doifrightpageelse
>{\cldcontext{"\letterpercent d",(\pagenumber+1)/2}}
>{}
> \stopsetups
>
> \setupfootertexts [\directsetup{Pagenumber}]
>
> \setupbodyfont [pagella,9pt]
>
>
> \starttext
>
> \startstandardmakeup
> Hello world!
> \stopstandardmakeup
>
> \dorecurse{3}{TEST\page}
>
> \stoptext
>
>
> Error:
>
>
> \cldcontext #1->\directlua {context(#1)}
>
> \ignorecrlf \directsetup {Pagenumber}
> {}{}{}
> \secondoftwoarguments #1#2->#2
>
> \page_layouts_process_element_single_indeed ...#4}
> \fi \endgroup
> \page_layouts_process_element_single ...#1#2#3{#4}
> \fi
> ...th {\hss \layoutelementparameter \c!middletext
> \hss }\kern -\makeupwidth ...
>
>
> What do i miss here? I am stumid…
>
> Willi
> ___
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### [NTG-context] Troubles with the \cldcontext command
Hello!
I have the following code, which should manipulate the page number. However I
get an error:
MWE:
\setuppapersize [A6] [A6]
\setuppagenumbering[location=none]
\startsetups [Pagenumber]
\doifrightpageelse
{\cldcontext{"\letterpercent d",(\pagenumber+1)/2}}
{}
\stopsetups
\setupfootertexts [\directsetup{Pagenumber}]
\setupbodyfont [pagella,9pt]
\starttext
\startstandardmakeup
Hello world!
\stopstandardmakeup
\dorecurse{3}{TEST\page}
\stoptext
Error:
\cldcontext #1->\directlua {context(#1)}
\ignorecrlf \directsetup {Pagenumber}
{}{}{}
\secondoftwoarguments #1#2->#2
\page_layouts_process_element_single_indeed ...#4}
\fi \endgroup
\page_layouts_process_element_single ...#1#2#3{#4}
\fi
...th {\hss \layoutelementparameter \c!middletext
\hss }\kern -\makeupwidth ...
What do i miss here? I am stumid…
Willi
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### Re: [NTG-context] Write your own module?
Hi Gerard,
the easiest is probably to put such a module into the texmf-tree i.e in
../texmf-project/tec/context/third/yourmodulename
Do not to forget to regenerate the filedatabase.
Willi
> On 26 Mar 2019, at 12:20, Geert Verhaag wrote:
>
> Hi,
>
> I'd like to start writing a module, and test it using ConTeXt MkIV standalone
> installation.
>
> Dived into wiki.contextgarden.net but was unable to find a basic tutorial on
> how to tackle this.
>
> Yes, I did find a module template, but can't figure out where the module
> should go such that ConTeXt can find and load it.
>
> Any hint would be very helpful.
>
>
> Regards,
> Gerard
> ___
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>
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### Re: [NTG-context] Small pages and large framed texts
Gosh Wolfgang! Thank you so much for your piece of code! — It starts to look
nicer and nicer in my little project :-)
Kindest regards
Willi
> On 20 Mar 2019, at 22:31, Wolfgang Schuster
> wrote:
>
> Willi Egger schrieb am 20.03.19 um 22:11:
>> It’s me again…
>> I appears that I was not clear enough, though I am happy about the
>> possibility of using textbackground.
>> What I must do is to prepare a list of ConTeXt commands on a very small
>> page. So the specific question is, how I can influence the
>> \placelistofsorts[texcommand] in such a way, that the framed pieces break
>> over the page.
>
> \usemodule [setups]
>
> \setuppapersize [A6] [A6]
>
> \setupbodyfont [pagella,9pt]
>
> \definetextbackground
> [SetupsParameter]
> [before=\blank,
> after=\blank,
> topoffset=10pt,
> leftoffset=10pt,
> location=paragraph,
> frame=on]
>
> \startsetups [xml:setups:start]
> \starttextbackground [SetupsParameter]
> \stopsetups
>
> \startsetups [xml:setups:stop]
> \stoptextbackground
> \stopsetups
>
> \starttext
>
> \startsection[title={Short Version of the Command}]
>
> \cmdshortsetup [setupframed]
> \cmdshortsetup [setupinteraction]
>
> \stopsection
>
> \startsection[title={\TEX-commands}]
>
> \placesetup
>
> \stopsection
>
> \stoptext
>
> Wolfgang
>
> ___
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> Wiki!
>
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### Re: [NTG-context] Small pages and large framed texts
It’s me again…
I appears that I was not clear enough, though I am happy about the possibility
of using textbackground.
What I must do is to prepare a list of ConTeXt commands on a very small page.
So the specific question is, how I can influence the
\placelistofsorts[texcommand] in such a way, that the framed pieces break over
the page.
\usemodule[x][set-11]
\setuppapersize[A6][A6]
\setupbodyfont[pagella,rm,10pt]
\starttext
\startsection[title=hSort Version of the Command]
\shortsetup{setupframed}
\shortsetup{setupinteraction}
\stopsection
\startsection[title=\TEX -commands]
\placelistofsorts[texcommand]
\stopsection
\stoptext
Willi
> On 20 Mar 2019, at 20:48, Willi Egger wrote:
>
> Thank you Wolfgang, I will try this!
>
> Willi
>
>> On 20 Mar 2019, at 18:26, Willi Egger wrote:
>>
>> Hi,
>>
>> I deal with a small project, in which I should be able to make a framed text
>> break over the page. — Does anyone have an idea how to achieve this?
>>
>> \setuppapersize[A6][A6]
>>
>> \setupbodyfont[pagella,rm,10pt]
>>
>>
>> \starttext
>> \framedtext
>> {\dorecurse{3}{\input ward\blank}}
>> \stoptext
>>
>>
>> Any hints would be welcome
>>
>> Willi
>> ___
>> the Wiki!
>>
>> maillist : [email protected] /
>> http://www.ntg.nl/mailman/listinfo/ntg-context
>> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
>> archive : https://bitbucket.org/phg/context-mirror/commits/
>> wiki : http://contextgarden.net
>> ___
>
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
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### Re: [NTG-context] Small pages and large framed texts
Thank you Wolfgang, I will try this!
Willi
> On 20 Mar 2019, at 18:26, Willi Egger wrote:
>
> Hi,
>
> I deal with a small project, in which I should be able to make a framed text
> break over the page. — Does anyone have an idea how to achieve this?
>
> \setuppapersize[A6][A6]
>
> \setupbodyfont[pagella,rm,10pt]
>
>
> \starttext
> \framedtext
> {\dorecurse{3}{\input ward\blank}}
> \stoptext
>
>
> Any hints would be welcome
>
> Willi
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
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### [NTG-context] Small pages and large framed texts
Hi,
I deal with a small project, in which I should be able to make a framed text
break over the page. — Does anyone have an idea how to achieve this?
\setuppapersize[A6][A6]
\setupbodyfont[pagella,rm,10pt]
\starttext
\framedtext
{\dorecurse{3}{\input ward\blank}}
\stoptext
Any hints would be welcome
Willi
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### Re: [NTG-context] Blogging about ConTeXt at Hostsharing
Thank you for sharing, nice blog, and nice flyers too!
Willi
> On 15 Mar 2019, at 16:46, Jan U. Hasecke wrote:
>
> Dear all,
>
> with your kind help I was able to establish an inhouse workflow to
> produce print material for my hosting cooperative Hostsharing.
>
> We are going to use ConTeXt for flyers, writing pads, business cards,
> posters and published documents such as sustainability reports.
>
> Many thanks to all who supported me in this mailing list.
>
> Being still a novice in ConTeXt I am going to blog about our experiences
> starting today with this post.
>
> https://www.hasecke.eu/post/werbemittel-mit-context-gestalten/
>
> The text is in German only. I hope to find the time to write an English
> version in the near future.
>
> If anyone of you is visiting the Chemnitzer Linux-Tage this weekend join
> us at our Hostsharing booth to see the printed results. Our booth is not
> far away from the DANTE booth.
>
> https://chemnitzer.linux-tage.de/2019/de/programm/live
>
> Thanks a lot and a happy weekend
> juh
>
> --
> Hostsharing eG – die Hosting-Genossenschaft
> Souveränität – Nachhaltigkeit – Exzellenz
> https://www.hostsharing.net
> ___
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> Wiki!
>
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### Re: [NTG-context] lua-error when asking for the fontame
Thank you Hans!
> On 9 Mar 2019, at 10:12, Hans Hagen wrote:
>
> On 3/8/2019 11:16 PM, Willi Egger wrote:
>> \setupbodyfont[pagella,rm,12pt]
>> \starttext
>> This text is written in \font\fontname
>> \stoptext
>
> > This text is written in \fontname\font
>
> Hans
>
>
>
> -
> Hans Hagen | PRAGMA ADE
> Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
> tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> -
> ___
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>
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### [NTG-context] lua-error when asking for the fontame
Hello,
today I updated ConTeXt to the version of 2019-03-05.
While testing a type-script I got an error, when I ask for the font name.
lua error > lua error on line 1 in file /test.tex:
#1 to 'lower' (string expected, got nil)
MWE:
\setupbodyfont[pagella,rm,12pt]
\starttext
This text is written in \font\fontname
\stoptext
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### Re: [NTG-context] ARIAL and hebrew
Thank you Arthur for your reply,
Looking at your result it is indeed ok. On my laptop (MacOS) and my brother’s
(Ubuntu), the described problem occurs. -- I thought already, it is related to
the font itself. I tried in the meantime Liberation-Regular-Sans which gives
the right result.
Willi
> On 4 Mar 2019, at 08:12, Arthur Reutenauer
> wrote:
>
> On Sun, Mar 03, 2019 at 11:47:24PM +0100, Willi Egger wrote:
>> I have a little project for preparing a vocabulary for an Ivrith student. —
>> The text should be typeset with Arial. However, when I try to use it I get
>> the vowel points between the glyphs instead of thereunder.
>
>
> https://wiki.contextgarden.net/Arabic_and_Hebrew#Hebrew,
> works well from me:
>
> cut before
> \starttext
>
> \definedfont[name:arial*hebrew]
> Hello, World!
>
> \setupalign[r2l]
> בְּרֵאשִׁית, בָּרָא אֱלֹהִים, אֵת הַשָּׁמַיִם, וְאֵת הָאָרֶץ. וְהָאָרֶץ,
> הָיְתָה תֹהוּ וָבֹהוּ, וְחֹשֶׁךְ, עַל-פְּנֵי תְהוֹם; וְרוּחַ אֱלֹהִים,
> מְרַחֶפֶת עַל-פְּנֵי הַמָּיִם. וַיֹּאמֶר אֱלֹהִים, יְהִי אוֹר; וַיְהִי-אוֹר.
> וַיַּרְא אֱלֹהִים אֶת-הָאוֹר, כִּי-טוֹב; וַיַּבְדֵּל אֱלֹהִים, בֵּין הָאוֹר
> וּבֵין הַחֹשֶׁךְ. וַיִּקְרָא אֱלֹהִים לָאוֹר יוֹם, וְלַחֹשֶׁךְ קָרָא
> לָיְלָה; וַיְהִי-עֶרֶב וַיְהִי-בֹקֶר, יוֹם אֶחָד.
>
> \stoptext
> cut after
>
> Best,
>
> ARrthur
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
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### [NTG-context] ARIAL and hebrew
Good evening!
I have a little project for preparing a vocabulary for an Ivrith student. — The
text should be typeset with Arial. However, when I try to use it I get the
vowel points between the glyphs instead of thereunder. — So my question is,
does anybody have experience with the use of Arial for typesetting Hebrew?
Kinde regards
Willi
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### Re: [NTG-context] Latest changes in some size registers
Wolfgang I would like to have your capacity of remembering things… Thank you so
much!
Willi
> On 25 Feb 2019, at 23:30, Wolfgang Schuster
> wrote:
>
> Willi Egger schrieb am 25.02.19 um 22:44:
>> Hi Wolfgang,
>>
>> that is a nice coincidence! I was stuck just today with this very issue!
>> Thank you for this information.
>
> You can try the two solutions (“grid=no” or “strut=no”) from this old thread:
> https://mailman.ntg.nl/pipermail/ntg-context/2018/093250.html
>
> Wolfgang
>
> ___
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> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
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### Re: [NTG-context] Latest changes in some size registers
Hi Wolfgang,
that is a nice coincidence! I was stuck just today with this very issue! Thank
you for this information.
Best
Willi
> On 25 Feb 2019, at 18:39, Wolfgang Schuster
> wrote:
>
> Martin Bruchanov schrieb am 22.02.19 um 04:37:
>> Hi all,
>>
>> I have some very condensed documents which should fit on one page:
>>
>> http://gnulinux.guru/bash_cheatsheet.pdf
>>
>> Without any major change in style definition, there is more space around
>> sections or itemize:
>>
>> http://gnulinux.guru/bash_cheatsheet_diff.pdf
>>
>> Source code is here:
>>
>> https://github.com/BruXy/gnulinux.guru/tree/master/bash_tahak
>>
>> Did I miss some update which has introduced some different length settings?
>>
>> I have version: 2019.02.14 16:57
>
> The columns-environment uses now the newer mixedcolumns code
> which create by default different spaces around section titles.
>
> The old columns code can be loaded as a module with
> \usemodule[old-multicolumns]
>
> Wolfgang
>
> ___
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> Wiki!
>
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### [NTG-context] A strange request...
Hi all,
I am siting with a project of making a “dwarsligger”, you know these books,
printed on bible-thin-printing paper, which are about 12 x 8 cm. One opens
them while holding them ‘landscape’ with the spine on the top…
Now there is of course a little struggle with the page numbering. The reading
page consists out of the even page together with the following uneven page. It
is easy to print on the uneven page a page number, however this will result in
uneven page numbers only throughout the book.
My question is, whether there is an algorithm to print page numbers as follows:
1 2 3 4 5 6 7 8 9 (this is the ordinary numbering)
1 2 3 4 5 (this is the requested numbering)
Does someone have an idea how to solve this?
Any hints are most appreciated!
Willi
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### Re: [NTG-context] New logo proposal
Hi,
here my humble personal thoughts:
I would say, that the multicolor version is dissecting the word ConTeXT to
unidentifiable crumbles. It is to my taste to less connected to typesetting,
herewith agreeing partly with Clyde.
The experiment of Taco however, has some charm. It includes the basic color of
the associations blue and it shows nicely the word TeX. - I have no objection
against a horizontal version, however in that case one might have to think to
put TeX in its original version. Although we ow all thanks to Don Knuth, I
believe that we use, as Hans mentions, the TeX logo in typesetting. It is
therefore not obligatory to reflect this also in the ConTeXt group logo.
I would welcome the version Taco prepared as a logo on the Wiki.
Kind regards
Willi
> On 29 Jan 2019, at 11:32, Taco Hoekwater wrote:
>
> Hi Paul,
>
> Nice idea, and I actually like the multi-color version although it is a
> bit too informal for some uses (but could be nice for the wiki).
>
> It would be more coherent if the color of the squares and the color of
> the letters trailed each other around the 7 options in the writing order
> for the word “CONTEXT” (C = orange+blue, O = blue+green, N = green+red
> etc.) But perhaps that is not what you wanted?
>
> On the blue logo I tried a little experiment myself, using the
> colors of http://group.contextgarden.net:
>
>
>
>
> WDYT?
>
> Side note: I like what gitlab does with the logo in the circle crop
> for its project icon. I believe it would be neat if that could be
> formalised into the logo itself, but a simple circle crop does not
> quite look right, and more advanced options like distorting the actual
> squares are outside of my inkscape knowledge. And it may not look
> that good in the end, anyway …
>
> I’ll be pleased to replace the current green logo on the wiki with
> your multi-color one, assuming there is a some agreement and no
> strong objections.
>
> Best wishes,
> Taco
>
>
>> On 29 Jan 2019, at 00:18, Paul Schalck wrote:
>>
>> Dear ConTeXt users and developers,
>>
>> I want to submit a new ConTeXt logo to you (link to GitLab project):
>>
>> https://gitlab.com/schickele/new-context-logo
>>
>> I made this logo in February 2018. At the time, I was planning to do some
>> video tutorials on ConTeXt (still work in progress), and I wanted a nice
>> looking visual clue for the thumbnails. Recently, I made a few minor tweaks
>> and thought it would be the right time to put it out there.
>>
>> The logo comes in two different layouts (hexagonal and horizontal), and each
>> layout comes in two color variations (multicolored and blue).
>>
>> The hexagonal layout is borrowed from the unofficial ConTeXt logo that has
>> been around for some time. I like the idea of a clean geometrical form, and
>> the hexagon reminds me of chemistry formulas -- one of the many application
>> fields of ConTeXt.
>>
>> The seven colors have mainly an esthetic purpose. They also denote the
>> flexibility of ConTeXt. I've added a monochromatic blue version because
>> shiny, saturated colors are not suitable for every case, and blue is
>> strongly associated with ConTeXt to me. Blue is also a reminder of Mark IV
>> and LuaTeX.
>>
>> The letters are set in Din17 EF, which I've licensed. I like its simple
>> shapes combined with a round and soft touch. It avoids consciously the very
>> connoted Computer Modern and can be seen as a modernized and also
>> Europeanized interpretation of the TeX tradition.
>>
>> This logo is just a humble proposal. Perhaps it is of some use to someone.
>> It could also make someone else want to create and share his or her logo --
>> that would be great.
>>
>> I'm using ConTeXt since 2006/07 for almost everything that contains text:
>> letters, presentations, invitations, résumés, certificates, manuals,
>> reports, flyers, university papers, book typesetting, exercise sheets, song
>> sheets, and I'm still amazed by how powerful, flexible and reliable it is.
>> Thanks to the whole community -- and particularly to the Dutch wizard -- for
>> making this possible!
>>
>> Greetings from Leimen, Germany
>>
>> Paul Schalck
>> ___
>> the Wiki!
>>
>> maillist : [email protected] /
>> http://www.ntg.nl/mailman/listinfo/ntg-context
>> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
>> archive : https://bitbucket.org/phg/context-mirror/commits/
>> wiki : http://contextgarden.net
>> ___
>
> Taco Hoekwater
> Elvenkind BV
>
>
>
>
> ___
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> Wiki!
>
> maillist : [email protected] /
### Re: [NTG-context] Sources of Tutorial.text.pdf
Aditya, no problem, I was of the same idea as you, but I thought it to be
correct to ask. But I am fine with you sending the sources to Tommaso!
Best
Willi
> On 28 Nov 2018, at 18:58, Aditya Mahajan wrote:
>
> On Wed, 28 Nov 2018, Willi Egger wrote:
>
>> As being one of the authors, yes I have these file still here. — When the
>> second author agrees I can deliver them to you. — However there is a warning
>> to be made, that the project is 10 years old and was built in pdfTeX/ConTeXt
>> MKII.
>
> Hi Willi,
>
> I sent the files to Thomas (without asking you I am afraid as I never thought
> that it would be an issue).
>
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> wiki : http://contextgarden.net
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### Re: [NTG-context] Sources of Tutorial.text.pdf
Hello Tommaso,
As being one of the authors, yes I have these file still here. — When the
second author agrees I can deliver them to you. — However there is a warning to
be made, that the project is 10 years old and was built in pdfTeX/ConTeXt MKII.
Kind regards
Willi
> On 28 Nov 2018, at 17:42, Tommaso Gordini wrote:
>
> Hi everyone,
> looking here and there on the Internet, I found a very interesting document
> by Aditya Mahajan and Willi Egger: Beginners Tutorial. ConTeXt
> (Tutorial-text.pdf), written in 2008 for the 2nd International ConTeXt User
> Meeting in Bohinj, Slovenia.
>
> This is a very interesting booklet, for me, congratulations to the authors!
>
> Are there also the sources of it, somewhere?
> I'd like to get some ideas for the ConTeXt guide in Italian that I'm planning.
> In particular, I appreciated the way in which the commands are presented: «do
> you need to do this? well, the commands that are useful to you are this and
> that». I really appreciated that. :-)
>
> Thomas
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### [NTG-context] TEST
Hello, sorry for this mail, this is a test for my new provider.
Happy TeXing!
Willi
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### [NTG-context] Unifraktur Maguntia features
Hi all,
is there somebody among the ConTeXt users, who has experience with the font
UnifrakturMaguntja (http://unifraktur.sourceforge.net/maguntia.html#)?
I tried all kind of approaches to get the font switching between lnum, tnum
pnum and onum. — I come to the conclusion that I am unable to subtract and add
features. I appreciate any help.
Please refer to the appended tex file.
Kind regards
willi
test-font-maguntia.tex
Description: Binary data
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### Re: [NTG-context] Problem installing a new font
Hi Taco,
Thank you so much!
1. yes forgot that /fonts piece in the given path.
2. Indeed mtxrun —generate is the key!
And 3 : it works!
Bedankt en groet
Willi
> On 12 Nov 2018, at 16:26, Taco Hoekwater wrote:
>
> Hi,
>
>> On 12 Nov 2018, at 15:39, Willi Egger wrote:
>>
>> I downloaded the font and put all *afm and *.pfb files into
>> ../texmf-fonts/data/public/aurical
>
> Not sure about that path. Should that not be
> ../texmf-fonts/fonts/data/public/aurical ?
>
> Nevertheless, the most important missing ingredient is
>
> mtxrun --generate
>
> Since ‘mtxrun —script fonts —reload’ does not scan the disk of the standard
> folders,
> it just queries the file cache.
>
> So the right order is:
>
> unzip
> mtxrun —generate
>
> That works for me.
>
> I just unzipped the CTAN download into my texmf-fonts, so I have
>
> hamster:texmf-fonts taco$mtxrun LukasSvatbaSlant.afm > > /Users/taco/context/tex/texmf-fonts/fonts/afm/public/aurical/LukasSvatbaSlant.afm > > hamster:texmf-fonts taco$ mtxrun --script font --list --file
> --pattern=LukasSvatbaSlant.afm
> familynameweight stylewidthvariant fontname
> filename subfont fontweight
> lukassvatba normal italic normal normallukassvatbaoblique
> LukasSvatbaSlant.afm conflict: oblique
>
> And it works:
>
> hamster:Downloads tacopdffonts HW.pdf > name type encoding emb > sub uni object ID > - --- > --- --- - > WIPANP+LMRoman12-Regular CID Type 0C Identity-H yes > yes yes 10 0 > SRZNPW+Lukas-Svatba CID Type 0C Identity-H yes > yes yes 11 0 > > Best wishes, > Taco > > > > > ___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### Re: [NTG-context] Problem installing a new font Hi, I downloaded the font and put all *afm and *.pfb files into ../texmf-fonts/data/public/aurical I reloaded the database with mtxrun —script fonts —roload. Then I was looking for the font in the database: mtxrun --script font --list --file --pattern=LukasSvatbaSlant.afm Strange enough I get no result. I tried to find the new cache I generated with the reload command. I can not find a new cache in ,,/texmf-cache/luatex-cache/context, what I see there is only a cache which has a date from 2013… I am puzzled, Where does Context nowadays deposit the cache files? Of course under these conditions Lukáš’s example does not work. — I think that the mechanism for loading type1 fonts works, I tried Lukáš’s MWE with Dolly and that does work nicely. Best wishs Willi > On 10 Nov 2018, at 21:56, Procházka Lukáš Ing. wrote: > > Hello, > > probably one of the basic questions and skills in ConTeXt, but the first case > for me: how to install a (downloaded third-party) font into ConTeXt: > > I downloaded font source files from > https://www.ctan.org/tex-archive/fonts/aurical/ and I unpacked the .zip > content, so I have now (see FileList.txt for full info): > > > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\FileList.txt > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\map > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\tfm > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\type1 > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm\public > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm\public\aurical > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm\public\aurical\AmiciLogo.afm > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm\public\aurical\AmiciLogoBold.afm > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm\public\aurical\AmiciLogoBoldRslant.afm > ... > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\type1\public\aurical\LukasSvatbaSlant.pfb > > > Trying to install the font the easiest way, I also copied files into my > ConTeXt dir, so I have also (see FileList2.txt): > > > d:\Ctx-Beta\tex\texmf\fonts\afm\public\aurical\AmiciLogo.afm > d:\Ctx-Beta\tex\texmf\fonts\afm\public\aurical\AmiciLogoBold.afm > d:\Ctx-Beta\tex\texmf\fonts\afm\public\aurical\AmiciLogoBoldRslant.afm > d:\Ctx-Beta\tex\texmf\fonts\afm\public\aurical\AmiciLogoBoldSlant.afm > ... > d:\Ctx-Beta\tex\texmf\fonts\type1\public\aurical\AmiciLogo.pfb > d:\Ctx-Beta\tex\texmf\fonts\type1\public\aurical\AmiciLogoBold.pfb > d:\Ctx-Beta\tex\texmf\fonts\type1\public\aurical\AmiciLogoBoldRslant.pfb > d:\Ctx-Beta\tex\texmf\fonts\type1\public\aurical\AmiciLogoBoldSlant.pfb > ... > > > I tried to follow instructions in 'mfonts.pdf' mentioned at > https://wiki.contextgarden.net/Fonts, but early I failed with (unknown) > "texfont" command cited here frequently. > > I also experimented somehow with "mtxrun --make --generate" and "mtxrun > script --font --reload --force" and with a simple show-font file which starts > with: > > > \definefont[FONT][AmiciLogo.afm] > ... > > > but the result is not written by AmiciLogo font. > > So - how to make ConTeXt aware of a third-party font and how to use the font > in the document? > > Best regards, > > Lukas > > > -- > Ing. Lukáš Procházka | mailto:[email protected] > Pontex s. r. o. | mailto:[email protected] | http://www.pontex.cz | > IDDS:nrpt3sn > Bezová 1658 > 147 14 Praha 4 > > Mob.: +420 702 033 > 396___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### Re: [NTG-context] Problem installing a new font I think, that for a type 1 font you will need to setup a set of typescripts, because you need to tell also the encoding to be used. A source of such typescripts can be looked up in the MKII environment. Willi > On 11 Nov 2018, at 15:28, Procházka Lukáš Ing. wrote: > > Hello, > > -- all attachments packed into one .zip -- > > probably one of the basic questions and skills in ConTeXt, but the first case > for me: how to install a (downloaded third-party) font into ConTeXt: > > I downloaded font source files from > https://www.ctan.org/tex-archive/fonts/aurical/ and I unpacked the .zip > content, so I have now (see FileList.txt for full info): > > > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\FileList.txt > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\map > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\tfm > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\type1 > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm\public > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm\public\aurical > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm\public\aurical\AmiciLogo.afm > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm\public\aurical\AmiciLogoBold.afm > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\afm\public\aurical\AmiciLogoBoldRslant.afm > ... > d:\Lukas\ConTeXt\Fonts\Aurical\fonts\type1\public\aurical\LukasSvatbaSlant.pfb > > > Trying to install the font the easiest way, I also copied files into my > ConTeXt dir, so I have also (see FileList2.txt): > > > d:\Ctx-Beta\tex\texmf\fonts\afm\public\aurical\AmiciLogo.afm > d:\Ctx-Beta\tex\texmf\fonts\afm\public\aurical\AmiciLogoBold.afm > d:\Ctx-Beta\tex\texmf\fonts\afm\public\aurical\AmiciLogoBoldRslant.afm > d:\Ctx-Beta\tex\texmf\fonts\afm\public\aurical\AmiciLogoBoldSlant.afm > ... > d:\Ctx-Beta\tex\texmf\fonts\type1\public\aurical\AmiciLogo.pfb > d:\Ctx-Beta\tex\texmf\fonts\type1\public\aurical\AmiciLogoBold.pfb > d:\Ctx-Beta\tex\texmf\fonts\type1\public\aurical\AmiciLogoBoldRslant.pfb > d:\Ctx-Beta\tex\texmf\fonts\type1\public\aurical\AmiciLogoBoldSlant.pfb > ... > > > I tried to follow instructions in 'mfonts.pdf' mentioned at > https://wiki.contextgarden.net/Fonts, but early I failed with (unknown) > "texfont" command cited here frequently. > > I also experimented somehow with "mtxrun --make --generate" and "mtxrun > script --font --reload --force" and with a simple show-font file which starts > with: > > > \definefont[FONT][AmiciLogo.afm] > ... > > > but the result is not written by AmiciLogo font. > > So - how to make ConTeXt aware of a third-party font and how to use the font > in the document? > > Best regards, > > Lukas > > > -- > Ing. Lukáš Procházka | mailto:[email protected] > Pontex s. r. o. | mailto:[email protected] | http://www.pontex.cz | > IDDS:nrpt3sn > Bezová 1658 > 147 14 Praha 4 > > Mob.: +420 702 033 396 > > ___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### Re: [NTG-context] Font Awesome Hraban, thank you! I got it working. Willi > On 30 Aug 2018, at 12:44, Henning Hraban Ramm wrote: > > Am 2018-08-30 um 11:13 schrieb Willi Egger : > >> I would like to use symbols form the Font Awesome. However I see that in >> symb-imp-fontawesome.mkiv all symbols except the [wheelchair] are commented. >> - What is the reason? > > Ah, that’s why they don’t work anymore. I didn’t look into that file... > > You can use my version that works with current Fontawesome 5.1.1 fonts: > https://github.com/fiee/ConTeXt/tree/master/symbols > Download the fonts from https://fontawesome.com/ > > Greetlings, Hraban > --- > https://www.fiee.net > http://wiki.contextgarden.net > https://www.dreiviertelhaus.de > GPG Key ID 1C9B22FD > > ___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### Re: [NTG-context] Font Awesome oeps, yes thats it! Thank you Arthur > On 30 Aug 2018, at 16:32, Arthur Reutenauer > wrote: > > On Thu, Aug 30, 2018 at 01:52:54PM +0200, Willi Egger wrote: >> I am sorry but I do not understand what you wrote: from the name sin the >> font? > > From the names in the font :-) > > Arthur > ___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### Re: [NTG-context] Font Awesome Hello Hans, I am sorry but I do not understand what you wrote: from the name sin the font? Willi > On 30 Aug 2018, at 13:40, Hans Hagen wrote: > > On 8/30/2018 11:13 AM, Willi Egger wrote: >> Good morning! >> I would like to use symbols form the Font Awesome. However I see that in >> symb-imp-fontawesome.mkiv all symbols except the [wheelchair] are commented. >> - What is the reason? > they are picked up from the name sin the font > > - > Hans Hagen | PRAGMA ADE > Ridderstraat 27 | 8061 GH Hasselt | The Netherlands > tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl > - > ___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### [NTG-context] Table of contents setup Hello, I am busy to typeset a book with Maguntia.ttf. I should prepare the TOC with leaders. However how can I get ConTeXT to use the same leader-size on all levels which need leaders? As in the given example the leaders are adapted to the size of the font. Secondly I would like to have the page numbers all in the same size, irrespective from the level. Thirdly, I would love to adapt the distance between the leader-dots to a bigger size. How to do that? Kind regards Willi ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### [NTG-context] Font Awesome Good morning! I would like to use symbols form the Font Awesome. However I see that in symb-imp-fontawesome.mkiv all symbols except the [wheelchair] are commented. - What is the reason? Best Willi ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### [NTG-context] Upcoming 12th ConTeXt Meeting in the Czech Republic Hello all! I would like to point you to the upcoming 12th ConTeXt-meeting. Details can be found on the ConTeXt-Wiki! (http://meeting.contextgarden.net/). The registration is open. Early bird registrations will be accepted until 1 of July. The 12th ConTeXt Meeting will take place in Sibřina, Czech Republic on September 2–8, 2018. Everybody is welcome! Kind regards Willi Egger cg-secretary ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### Re: [NTG-context] imposition with some rotated pages Hi Pablo, hm, it seems that this is a special issue. As I understand it you should separate the pages which are rotated. Then rotate them into another file. Finally use the [2UP] arranging for reassembling all pages. The built in impositioning tool in Context is typesetting first all pages upright. In an other run the pages are impositioned and rotaded as needed according the the schema chosen. There is therefore no way to make a booklet from your source directly, I hope you will find a way to separate the rotated pages! Best regards Willi > On 30 Jul 2017, at 20:55, Pablo Rodriguez wrote: > > Dear list, > > I have a PDF document in A4 paper size with some rotated pages. > > I would like to make a booklet of it: > >\setuppapersize [A5][A4, landscape] >\setuparranging [2UP] >\setuplayout > [backspace=0pt, >topspace=0pt, > width=middle, > height=middle, >location=middle, > header=0pt, > footer=0pt] >\setupinteractionscreen[option={landscape, paper}, copies=1] >\starttext >\filterpages[report.pdf][1:25][width=0pt] >\filterpages[report.pdf][27:30][width=0pt]%they are rotated >\filterpages[report.pdf][31:100][width=0pt] >\stoptext > > The rotated pages in the source PDF document are a problem here. > > The wiki contains the info that \filterpages may be rotated with > [orientation=90]. But this seems to be old, since it doesn’t work. > > If I add > \rotate[rotation=90]{\filterpages[report.pdf][27:30][width=0pt]}, > automatic scaling doesn’t work. And all pages will be considered as a > single image. > > Is there any way to have rotation for some pages in the source document > to get the right imposition? > > I’m afraid rotation comes from the source PDF document in this case. > > Many thanks for your help, > > Pablo > -- > http://www.ousia.tk > ___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### Re: [NTG-context] Problems with headers using margintext alternative Hi, I am not a guru, but I think that you should setup your pagesize properly. For the calculation of the paper-width margin widths are not used. The elements for calculations are the backspace and makeupwidth and the rest to sum up to the paperwidth as given in the definition of the papersize. Margins are kind of virtual. If text spills out of the margin then the backspace and the margin have to be adjusted. e.g. \setuplayout [location=middle, topspace=1.5cm, backspace=2cm, margin=18mm, width=middle] Location=middle tells only, that the lettersized paper should placed centered onto the lettersized paper, oversized. When I comment the line with insidesection= I get a consistent result i.e. that the text of the sections with start\stop in the text body starts one line to low compared to the traditional way of coding. Otherwise with this insidesection={\blank[-line]} it appears, that the text next uneven section numbers is typeset at the expected place, where text next to even section numbers is not. — This might indeed be something which Hans should look at. Best Will > On 29 Jul 2017, at 16:52, Rik wrote: > > Bump. > > The problem persists two updates later. > > In the picture below, the green line represents the edge of the page. > > > > Does anyone else get the same result? > -- > Rik > > On 2017-07-23 15:48, Rik Kabel wrote: >> The following example demonstrates two problems with alternative=margintext >> in \setuphead: >> • When used with start/stop sectioning, text following the title may be >> set on the wrong line. >> • Without regard to the type of sectioning, margintext titles may spill >> over the left edge of the margin and beyond the page frame. >> \setuppapersize >> [letter] >> [letter,oversized] >> \setuplayout >> [location={middle,middle}] >> \showframe >> \setuphead >> [chapter] >> [number=no, >> alternative=inmargin] >> \setuphead >> [section] >> [ >> alternative=margintext, >> insidesection={\blank[-line]}, >> ] >> \starttext >> \starttitle >> [title={Problem description}] >> \bgroup >> \setupwhitespace[medium] >> \startparagraph >> This demonstrates two problems with >> \type{alternative=margintext} in \tex{setuphead}: >> \startitemize[packed,n] >> \startitem >> When used with start/stop sectioning, text following the >> title may be set on the wrong line. >> \stopitem >> \startitem >> Without regard to the type of sectioning, \type{margintext} >> titles may spill over the left edge of the margin and beyond >> the page frame. (Oddly, \tex{paperwidth} is less than the >> sum of \tex{makeupwidth} and the margin widths and >> distances for both letter and A4 paper.) >> \stopitem >> \stopitemize >> \stopparagraph >> \startparagraph >> With start/stop sectioning, the text following the section >> title may begin one line below the start of the title. That >> can be remedied if there is no whitespace between paragraphs >> with \type{insidesection={\blank[-line]}}, but the remedy >> fails when there is whitespace, and increasing the correction >> has no effect. With traditional sectioning, the text appears >> baseline|-|aligned with the heading, as expected. The >> the correction has no effect in any case with traditional >> sectioning. >> \stopparagraph >> \startparagraph >> It makes no difference in any test how the paragraphs are >> delimited—blank lines, \tex{bpar}/\tex{epar}, >> \tex{startparagraph}/\tex{stopparagraph}, or \tex{par}. >> \stopparagraph >> \startparagraph >> Tested with standalone beta 2017.07.17 00:20. >> \stopparagraph >> \egroup >> \page >> \startchapter >> [title={Start/stop sectioning}] >> \startsection[title={Mis\-cel\-la\-neous quo\-ta\-tions}] >> \startparagraph >> \input jojomayer >> \stopparagraph >> \startparagraph >> \input carrol \wordright{No indent no whitespace.} >> \stopparagraph >> \stopsection >> \bgroup >> \setupwhitespace[medium] >> \startsection[title={Miscellaneous quotations}] >> \startparagraph >> \input jojomayer >> \stopparagraph >> \startparagraph >> \input carrol \wordright{No indent medium whitespace.} >> \stopparagraph >> \stopsection >> \egroup >> \bgroup >> \setupindenting[yes,small] >> \startsection[title={Miscellaneous quotations}] >> \startparagraph >> \input jojomayer >> \stopparagraph >> \startparagraph >> \input carrol \wordright{Small indent no whitespace.} >> \stopparagraph >> \stopsection >> \egroup >> \bgroup >> \setupwhitespace[medium] >> \setupindenting[yes,small] >> \startsection[title={Miscellaneous quotations}] >> \startparagraph >> \input jojomayer >> \stopparagraph >> ### Re: [NTG-context] Teletype in tabulate Ah, stupid me, should have known that. Thank you Hans! Willi > On 20 Apr 2017, at 17:17, Hans Hagen <[email protected]> wrote: > > On 4/20/2017 4:53 PM, Willi Egger wrote: >> Hi all, >> >> I have the context version 2017.04.16 12:32. >> >> Now I detect that here the tabulate environment throws an error when using >> the T key for teletype in the preamble. >> >> I am stuck… >> >> /Users/willi/Documents/TEXdata/lezingenMAPSNTG/Bachotex2017/test.tex: ! >> Missing number, treated as zero >> >> >> \unskip >> \tabl_tabulate_column_normal #1->\unskip >> \aligntab \ifconditional >> \c_tabl_ta... >> \tabl_tabulate_insert_body ...NC \paperheight \NC >> 29.000cm \NC \NR >> \tabl_tabulate_insert_content ...late_insert_body >> >> \tabl_tabulate_insert_foot... >> \tabl_tabulate_process ...tabulate_insert_content >> \crcr >> }}\anch_backgrounds_... >> l.14 \stoptabulate >> >> >> \starttext >> \starttabulate[|lT|r|] >> \NC \paperheight \NC 29.000cm \NC\NR >> \stoptabulate >> >> \stoptext > > because T is not \type > > \NC \type{\paperheight} \NC 29.000cm \NC\NR > > or > > \NC \string\paperheight \NC 29.000cm \NC\NR > > - > Hans Hagen | PRAGMA ADE > Ridderstraat 27 | 8061 GH Hasselt | The Netherlands > tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl > - > ___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### [NTG-context] Teletype in tabulate Hi all, I have the context version 2017.04.16 12:32. Now I detect that here the tabulate environment throws an error when using the T key for teletype in the preamble. I am stuck… /Users/willi/Documents/TEXdata/lezingenMAPSNTG/Bachotex2017/test.tex: ! Missing number, treated as zero \unskip \tabl_tabulate_column_normal #1->\unskip \aligntab \ifconditional \c_tabl_ta... \tabl_tabulate_insert_body ...NC \paperheight \NC 29.000cm \NC \NR \tabl_tabulate_insert_content ...late_insert_body \tabl_tabulate_insert_foot... \tabl_tabulate_process ...tabulate_insert_content \crcr }}\anch_backgrounds_... l.14 \stoptabulate \starttext \starttabulate[|lT|r|] \NC \paperheight \NC 29.000cm \NC\NR \stoptabulate \stoptext Kind regards Willi ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### Re: [NTG-context] Additional documentation/ Hello John, are you referring to the Columns manual? - Hans posted a message on February 9 last year, where he told about the reimplementation of columnsets. — I do not know what the status is and in how far the new implementation works differently from what is described in the columns manual. There is quite some info on columns and related stuff on http://wiki.contextgarden.net/Columns Kind regards Willi > On 19 Jan 2017, at 23:11, John Culleton wrote: > > I have been away from context for a few years and my memory is fading in > any case. I do remember a short tutorial that described how one could > insert a text block in between two text columns or at the side of a > column etc. I have downloaded the big manual today but that little > tutorial would help. My questions: > > 1.Do you recall what I am referring to? > 2. If so, what is its name? > 3. Is it current enough to be useful today? > > Blessings on all who respond. > -- > John Culleton > Wexfordpress > Book design and indexing. > > > ___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### Re: [NTG-context] Overlays and layers documentation? Apart from the link given you might also read the Metafun manual and parts of the Details manual. Willi > On 22 Nov 2016, at 14:04, Henri Menke wrote: > > On 11/21/2016 07:44 PM, Jaroslav Hajtmar wrote: >> Hello ConTeXist. >> >> Is there any documentation or manual, where I could read some details about >> using of overlays and layers in ConTeXt? I see on the Internet and wiki >> ConTeXtgarden some examples, but I would be interested in details relating >> to the default layers and their names, their order. Are there any >> restrictions (number, name, etc.) > > https://github.com/contextgarden/context-mirror/blob/beta/tex/context/base/mkiv/pack-box.mkiv > > Ctrl+F definelayer > > Documentation is provided inline. > >> >> Thanx >> >> Jaroslav Hajtmar >> >> >> >> ___ >> If your question is of interest to others as well, please add an entry to >> the Wiki! >> >> maillist : [email protected] / >> http://www.ntg.nl/mailman/listinfo/ntg-context >> webpage : http://www.pragma-ade.nl / http://context.aanhet.net >> archive : https://bitbucket.org/phg/context-mirror/commits/ >> wiki : http://contextgarden.net >> ___ >> > > ___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### Re: [NTG-context] Strange behaviour of itemize inside tabulate Thank you Herbert, this indeed solves the problem. Willi > On 20 Nov 2016, at 20:45, Herbert Voss <[email protected]> wrote: > > Am 20.11.2016 um 20:25 schrieb Willi Egger: > >> I have the following minimal example >> >> % \setupitemgroup >> %[itemize] >> %[each] >> %[autointro,packed] >> %[symbol=2] > > Use > > \setupitemgroup > [itemize] > [each] > [packed] > [symbol=2] > > > Herbert > > >> >> \starttext >> \starttabulate[|l|p|] >> \NC \bf Druk procedé \NC \bf Opmerking \NC\NR >> \NC Offset \NC \strut weinig problemen als onverpakt\crlf >> \NC\NR >> \NC Digitaal\NC beduidend lager i.v.m. warmte fixatie. >> >> \startitemize >> \startitem >> zo snel >> mogelijk weer verpakken na het printen. >> \stopitem >> \stopitemize\par >> \NC\NR >> \stoptabulate >> \stoptext >> >> When not uncommenting the setupitemgroup the tabulate appears as expected. >> However with the setupitemgroup enabled the row containing the itemize is >> shifted up and overlays the first row… >> >> Do I miss something? >> >> Thank you for looking at this. Kind regards >> >> Willi >> ___ >> If your question is of interest to others as well, please add an entry to >> the Wiki! >> >> maillist : [email protected] / >> http://www.ntg.nl/mailman/listinfo/ntg-context >> webpage : http://www.pragma-ade.nl / http://context.aanhet.net >> archive : https://bitbucket.org/phg/context-mirror/commits/ >> wiki : http://contextgarden.net >> ___ >> > > ___ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://context.aanhet.net > archive : https://bitbucket.org/phg/context-mirror/commits/ > wiki : http://contextgarden.net > ___ ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### [NTG-context] Strange behaviour of itemize inside tabulate Hello, I have the following minimal example % \setupitemgroup % [itemize] % [each] % [autointro,packed] % [symbol=2] \starttext \starttabulate[|l|p|] \NC \bf Druk procedé \NC \bf Opmerking \NC\NR \NC Offset \NC \strut weinig problemen als onverpakt\crlf \NC\NR \NC Digitaal\NC beduidend lager i.v.m. warmte fixatie. \startitemize \startitem zo snel mogelijk weer verpakken na het printen. \stopitem \stopitemize\par \NC\NR \stoptabulate \stoptext When not uncommenting the setupitemgroup the tabulate appears as expected. However with the setupitemgroup enabled the row containing the itemize is shifted up and overlays the first row… Do I miss something? Thank you for looking at this. Kind regards Willi ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___ ### [NTG-context] Chemical reaction... I am busy to edit an older article in which there are a couple of chemical fromulas and reactions. However, I am stuck because the following throws me an error when uncommenting the line with “\chemical{2H^\oplus}{~waterstof (zuur)}” (something with
inserted…)
Another aspect is, that the {DEZ} does not appear. Further the {zinkion} and
{ethan} appear not as text under the formula but as text next to it.
\starttext
\placeformula
\startformula
\chemical{(C_2H_5)_2Zn}{DEZ}
\chemical{PLUS}
% \chemical{2H^\oplus} {waterstof (zuur)}
\chemical{GIVES}
\chemical{Zn^{2\oplus}}{zinkion}
\chemical{PLUS}
\chemical{2(C_2H_6)}{ethan}
\stopformula
\stoptext
Thank you for hints, what I am missing here…
Kind regards
Willi
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### Re: [NTG-context] Clickable question/answer numbers (Otared Kavian)
Otared,
thank you for this nice example!
Willi
> On 7 Nov 2016, at 04:21, Otared Kavian wrote:
>
> Dear Dalyoung,
>
> I guess you are typesetting the wrong file, or you have put the last code I
> sent into a file which contains something of the previous codes…
> Indeed in the last file I sent (which I am sending again at the end of this
> message.
>
> Please test the code below and let me know if you encunter a problem.
>
> Best regards: OK
> Here, following Wolfgang Schuster's ideas,
> we define some macros allowing to couple
> Questions and Answers in an automatic way
> Upon clicking on an interactive title for Question or Answer
> one goes to the corresponding Answer or Question
>
> \setupinteraction[state=start]
>
> % We define two counters which follow the numbers
> % appearing in Question and Answer
>
> \newcounter\QuestionCounter
>
> % We create two commands to be used in the
> % enumeration environments
> % Note that the check for trial typestting
> % \doifnotmode{*trialtypesetting}
> % is necessary in order to avoid unwanted incrementation
> \define[1]\QuestionTextCommand
> {\doifnotmode{*trialtypesetting}
> {\doglobal\increment\QuestionCounter
> \pagereference[question:\QuestionCounter]}%
> {#1}}
>
> {\doifnotmode{*trialtypesetting}
> {#1}}
>
> % We define here two enumeration environments for
> \defineenumeration[question]
> [text=Question,
> number=yes,
> prefix=yes,
> prefixsegments=chapter,
>
> number=yes,
> prefix=yes,
> prefixsegments=chapter,
> coupling=question]
>
> % Each question is followed immediately by its answer.
> % The answers are put in a block which will be used later
>
> % We define a command used after a
> % Question for which no Answer is provided
> % Since the block commands
> % cannot be used directly in a macro definition
> % we use a trick...
> % In the buffer the two counters associated to Answer
> % are incremented...
> \stopbuffer
>
> % ...and then the above buffer is invoked
>
> % example of use:
> \starttext
> \startchapter[title=Questions]
>
> \startquestion[q:1]
> Prove that ${\rm e}\sim 2.73$ is irrational.
>
> This is the first question, with its own reference, for later use.
> \stopquestion
>
> This is the answer to the first question (to \in{Question}[q:1]).
>
> \startquestion
> This is the second question, without its own reference.
> \stopquestion
>
> This is the answer to the second question.
>
> (Note that this answer has a reference named \type{a:Test}).
>
> \startquestion[q:Obvious]
> This is the third question, an easy one, without a given solution.
> \stopquestion
>
> % we increment here the counters for Answer
>
> \startquestion[q:2]
> This is the fourth question with its own reference.
> \stopquestion
>
> This is the answer to the fourth question: use the result of
> \in{Question}[q:1].
>
> \startquestion
> This is the fifth question, without its own reference.
>
> ({\it Hint:} look again at \in{Question}[q:Obvious]).
> \stopquestion
>
>
> \stopchapter
>
> % Here we say ownnumber=1, in order to match the prefix
> % of numbers associated to Answer
> \stopchapter
>
> \stoptext
>
>
>
>
>> On 6 Nov 2016, at 23:43, Jeong Dal wrote:
>>
>> Dear Otared,
>>
>> Hi,
>> I run the given code and got an error message as following.
>>
>> tex error > tex error on line 1 in file virtual://block.answer.2: !
>> Undefined control sequence
>>
>>[Q:test]
>>
>>
>>
>> Would you please tell me how to avoid
### Re: [NTG-context] Creeps (binding gutter / margin correction in imposition)
Hi Hraban,
I am not sure about what you say. The page shifting/creep correction is added
individually per spread. If this is done correctly then the typeset area is on
all pages the same width and has after folding and cutting the same outer
margin.
As Wolfgang reports look into \definepageshift cum suis.
Kind regards
Willi
> On 7 Nov 2016, at 08:33, Henning Hraban Ramm wrote:
>
> Hi together,
>
> this is not really a practical request, but an interesting (I think) idea...
>
> ConTeXt can do simple imposition (arranging pages on sheets, see
> \setuparranging), but in professional imposition you need to compensate for
> the paper thickness in folds to keep pages readable - you can move the outer
> pages of a fold out of the gutter (spine), or move the inner pages to the
> spine. (This is called creep in English, Bundversatz in German.) That means,
> your outer margin will have different width, depending on the position of the
> page in its fold.
>
>
> A guy on the LilyPond mailing list had the interesting idea to adapt the line
> width to this creep, to keep an even outer margin - it would mean that TeX
> needs to know about imposition while breaking lines.
>
> What do you think?
>
>
> Greetlings, Hraban
> ---
> http://www.fiee.net
> http://wiki.contextgarden.net
> GPG Key ID 1C9B22FD
>
> ___
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### Re: [NTG-context] Remove files that are not needed (Metafun)
context —purgeall is your friend. The pdfs you will have to delete manually.
Willi
> On 12 jul. 2016, at 12:44, Fabrice Couvreur
> wrote:
>
>
> Hello,
> One of my command uses a macro build from Metafun. The compilation generates
> many files.
> How to delete files in the formats mpgraph.log, mpgraph.mpy, mpgraph.pdf,
> mpgraph.tex and mpgraph.tuc ?
> thank you,
> Fabrice
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### Re: [NTG-context] A rather special case of a chapter-start
Thank you Wolfgang,
indeed, that was the problem!
Kind regrards
Willi
> On 5 jun. 2016, at 20:44, Wolfgang Schuster <[email protected]>
> wrote:
>
>> Willi Egger 5. Juni 2016 um 20:30
>> Indeed in the example it is stated header=empty, however in no case I get
> You set different texts for left/right pages with no text for even numbered
> pages which you now get in your example.
>
>
> Wolfgang
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### Re: [NTG-context] A rather special case of a chapter-start
Indeed in the example it is stated header=empty, however in no case I get the
In the meantime I chose another approach:
\setuppagenumbering[location=]
\setuplayout
\starttext
\start
\midaligned{\bf TEXT before chapter title}
\startchapter[title=test]
\input knuth
\stopchapter
\stop
\startchapter[title=Normal chapter start]
\input knuth
\stopchapter
\stoptext
Thanks for looking at this!
Kind regards
Willi
> On 5 jun. 2016, at 19:35, Hans Hagen <[email protected]> wrote:
>
> On 6/5/2016 2:10 PM, Willi Egger wrote:
>> Dear list!
>>
>> I have a book, in which I should repeat the title of the book on top of the
>> first chapter title. - I thought that should be solvable with playing with
>> the headertexts. However it seems, that it is not possible to force ConTeXt
>> to place the headertexts-contents for a chapter, yes it displays the header
>>
>> MWE:
>> \setuppagenumbering[location=]
>> \setuplayout
>> [state=normal]
>> [Why not visible?][][][]
>> [chapter]
>> \setupbackgrounds
>> [frame=on]
>>
>> \starttext
>> \input ward
>>
>> \page
>>
>> \startchapter[title=test]
>> \input knuth
>> \page
>> \input ward
>> \stopchapter
>> \stoptext
>>
>> Hints would be welcome!
>
> because you say
>
>
>
> -
> Hans Hagen | PRAGMA ADE
> Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
> tel: 038 477 53 69 | www.pragma-ade.com | www.pragma-pod.nl
> -
> ___
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### [NTG-context] A rather special case of a chapter-start
Dear list!
I have a book, in which I should repeat the title of the book on top of the
first chapter title. - I thought that should be solvable with playing with the
headertexts. However it seems, that it is not possible to force ConTeXt to
place the headertexts-contents for a chapter, yes it displays the header space
MWE:
\setuppagenumbering[location=]
\setuplayout
[state=normal]
[Why not visible?][][][]
[chapter]
\setupbackgrounds
[frame=on]
\starttext
\input ward
\page
\startchapter[title=test]
\input knuth
\page
\input ward
\stopchapter
\stoptext
Hints would be welcome!
Kind regards
Willi
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### Re: [NTG-context] [dante-ev] Kooperation mit der PDF Association
I suppose that it is fine that Dante is a member of that association. We will
lift on their possibilities to fetch info and being involved with it. I think,
that the ConTeXt group as such has little to profit from a membership…
Best wishes
Willi
> On 21 apr. 2016, at 20:15, Mojca Miklavec
> wrote:
>
> On 21 April 2016 at 19:24, Hans Hagen wrote:
>> On 4/21/2016 6:28 PM, Henning Hraban Ramm wrote:
>>>
>>> Hello ConTeXt group activists!
>>>
>>> DANTE just became a partner organization of PDF association, see message
>>> below.
>>> Wouldn’t it make sense for our group (and NTG and TUG etc.) to do the
>>> same?
>>
>> I suppose that Dante, the largest tex user group being around, being a
>> member of that group means that the rest of the user groups can save
>> themselves the trouble and money ...
>
> The website says:
>"Non-profit organizations can become members without charge as
> Partner Organizations."
>
> So maybe the ConTeXt Group could indeed apply for membership?
>
> If we would have to pay the fee, there is no way we could afford it anyway.
>
> Mojca
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### Re: [NTG-context] adding font feature tnum in the TOC
Thank you Hans,
I think we will keep such things with fonts as before. So I am happy about the
solution I got from Wolfgang and it works for me here…The latter is the most
important.
Kind regards
Willi
> On 30 mrt. 2016, at 08:26, Hans Hagen <[email protected]> wrote:
>
> On 3/29/2016 8:38 PM, Willi Egger wrote:
>> I underrstand this, however then I do not get tabular figures…
>
> These things also depend on the font. Some fonts (maybe taken from type ones)
> have old styles in the regular digit slots so effectively they always have
> onum=yes hardcoded and maybe alternatives that kick in when you choose
> another *num (turning onum off doesn't help then). (The same can be true for
> other features; unfortunately it's a bit of a mess out there. And if needed
> we can fix such things in lfg files for specific fonts.)
>
> Hans
>
> -
> Hans Hagen | PRAGMA ADE
> Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
> tel: 038 477 53 69 | www.pragma-ade.com | www.pragma-pod.nl
> -
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>
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### Re: [NTG-context] adding font feature tnum in the TOC
Hello Wolfgang,
indeed if one uses pagella it is true what you say.
If I use Seravek, which has oldstuyle figures also, then it does not work in
the same way.
I tested with \addfeature[oldstyle] which is defined as
\definefontfeature[oldstyle][default][sript=latn,onum=yes]
With this feature enabled I get oldstyle figures in the text but proportional
numbers in de TOC, not oldstyle.
Normally I have oldstyle not enabled. So when i use the + instead of the = then
I get tabular figures.
May be that there is something organized differently in the two fonts?
Willi
> On 29 mrt. 2016, at 20:36, Wolfgang Schuster <[email protected]>
> wrote:
>
>> Willi Egger 29. März 2016 um 20:29
>> Hello Wolfgang,
>>
>> I used your solution. However I think instead of an “=“ it should be “+”.
> No, the = was intentional because I had to get rid of the onum setting.
>
> Wolfgang
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### Re: [NTG-context] adding font feature tnum in the TOC
I underrstand this, however then I do not get tabular figures…
Willi
> On 29 mrt. 2016, at 20:36, Wolfgang Schuster <[email protected]>
> wrote:
>
>> Willi Egger 29. März 2016 um 20:29
>> Hello Wolfgang,
>>
>> I used your solution. However I think instead of an “=“ it should be “+”.
> No, the = was intentional because I had to get rid of the onum setting.
>
> Wolfgang
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### Re: [NTG-context] adding font feature tnum in the TOC
Hello Wolfgang,
I used your solution. However I think instead of an “=“ it should be “+”.
I wikified this issue.
Kind regards
Willi
> On 29 mrt. 2016, at 17:48, Willi Egger <[email protected]> wrote:
>
> Wolfgang!
>
> Many thanks for this! - I get the result I wanted to.
>
> Kind regards
>
> Willi
>> On 29 mrt. 2016, at 17:33, Wolfgang Schuster <[email protected]>
>> wrote:
>>
>>> Willi Egger 29. März 2016 um 15:11
>>> Hi,
>>>
>>> hm, I am a little puzzled…
>>>
>>> If I am correct then one should be able to enable the font feature tnum for
>>> the page-numbers with “pagecommand=“.
>>>
>>> I have
>>>
>>> [section]
>>> [aftersection=\page, textstyle=\bfd, numberstyle=\bfd, align=middle,
>>> after={\godown[-1\lineheight]}, number=no]
>>>
>>>
>>> However if I do this then I get the pagenumber prefixed with ‘section’ e.g.
>>>
>>> bbb bar buch bühne section3
>>>
>>> What am I doing in the wrong way?
>> \setuplist[chapter][pagestyle={\feature[=][tabularnumbers]}]
>>
>> \definefontfeature[default][default][onum=yes]
>>
>> \setupbodyfont[pagella]
>>
>> \starttext
>>
>> \setcounter[userpage][100]
>>
>> \completecontent
>>
>> \dorecurse{20}{\expanded{\chapter{Chapter \recurselevel}}}
>>
>> \stoptext
>>
>> ___
>> the Wiki!
>>
>> maillist : [email protected] /
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>
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### Re: [NTG-context] adding font feature tnum in the TOC
Wolfgang!
Many thanks for this! - I get the result I wanted to.
Kind regards
Willi
> On 29 mrt. 2016, at 17:33, Wolfgang Schuster <[email protected]>
> wrote:
>
>> Willi Egger 29. März 2016 um 15:11
>> Hi,
>>
>> hm, I am a little puzzled…
>>
>> If I am correct then one should be able to enable the font feature tnum for
>> the page-numbers with “pagecommand=“.
>>
>> I have
>>
>> [section]
>> [aftersection=\page, textstyle=\bfd, numberstyle=\bfd, align=middle,
>> after={\godown[-1\lineheight]}, number=no]
>>
>>
>> However if I do this then I get the pagenumber prefixed with ‘section’ e.g.
>>
>> bbb bar buch bühne section3
>>
>> What am I doing in the wrong way?
> \setuplist[chapter][pagestyle={\feature[=][tabularnumbers]}]
>
> \definefontfeature[default][default][onum=yes]
>
> \setupbodyfont[pagella]
>
> \starttext
>
> \setcounter[userpage][100]
>
> \completecontent
>
> \dorecurse{20}{\expanded{\chapter{Chapter \recurselevel}}}
>
> \stoptext
>
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### [NTG-context] adding font feature tnum in the TOC
Hi,
hm, I am a little puzzled…
If I am correct then one should be able to enable the font feature tnum for the
page-numbers with “pagecommand=“.
I have
[section]
[aftersection=\page, textstyle=\bfd, numberstyle=\bfd, align=middle,
after={\godown[-1\lineheight]}, number=no]
However if I do this then I get the pagenumber prefixed with ‘section’ e.g.
bbb bar buch bühne section3
What am I doing in the wrong way?
Kind regards
Willi
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### Re: [NTG-context] What is wrong with PocketDiary module?
Hi,
did you try to use another font? Seravek is a commercial font, so you might use
Pagella.
I tested the module here with Pagella and Seravek and it works fine with
ConTeXt version 2016.03.13 23:40.
WIlli
> On 17 mrt. 2016, at 17:10, DesdeChaves wrote:
>
> PocketDiary module don't works anymore with the actual Context version.
>
>
> What is wrong? Why this module isn't more supported?
>
>
> Thanks
>
> Jorge
>
> context PocketDiary.tex
>
> mtx-context | run 1: luatex
> --fmt="/Applications/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/luatex/cont-en"
> --jobname="PocketDiary"
> --lua="/Applications/context/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/luatex/cont-en.lui"
> --no-parse-first-line --c:currentrun=1 --c:fulljobname="./PocketDiary.tex"
> --c:input="./PocketDiary.tex" --c:kindofrun=1 --c:maxnofruns=9 "cont-yes.mkiv"
> This is LuaTeX, Version beta-0.89.4 (TeX Live 2016/dev)
> system commands enabled.
> open source > 1 > 1 >
> /Applications/context/tex/texmf-context/tex/context/base/mkiv/cont-yes.mkiv
>
> ConTeXt ver: 2016.03.13 23:40 MKIV beta fmt: 2016.3.14 int: english/english
>
> open source > 2 > 2 >
> /Applications/context/tex/texmf-context/tex/context/base/mkiv/cont-new.mkiv
> close source> 2 > 2 >
> /Applications/context/tex/texmf-context/tex/context/base/mkiv/cont-new.mkiv
> system > files > jobname 'PocketDiary', input './PocketDiary',
> result 'PocketDiary'
> fonts > latin modern fonts are not preloaded
> languages > language 'en' is active
> open source > 2 > 3 >
> /Users/jorgem/Desktop/t-scancsv_ConTeXt_module/PocketDiary.tex
> resolvers > modules > 'pocketdiary' is loaded
> open source > 3 > 4 > t-pocketdiary.tex
> open source > 4 > 5 >
> /Applications/context/tex/texmf-context/tex/context/base/mkiv/symb-imp-mvs.mkiv
> close source> 4 > 5 >
> /Applications/context/tex/texmf-context/tex/context/base/mkiv/symb-imp-mvs.mkiv
> fonts > symbols > library 'mvs' loaded
> colors > 'rgb' color space is supported
> colors > 'cmyk' color space is supported
> close source> 3 > 5 > t-pocketdiary.tex
> fonts > typescripts > unknown library 'seravek'
> fonts > typescripts > unknown library 'Seravek'
> fonts > 'fallback modern-designsize ss 9pt' is loaded
> system > '1.1' arranged at '1'
>
> tex error > tex error on line 147 in file virtual://buffer.Week.2: !
> You can't use \prevdepth' in restricted horizontal mode
>
>
> \nointerlineskip ->\prevdepth
> -\thousandpoint
> \tabl_ntb_row_align_stop_inject ...ointerlineskip
> \ifenableTBLbreak
> \tabl_nt...
> \tabl_ntb_flush_content ...table \the \t_tabl_ntb
> \dostoptagged
> \tabl_ntb_table_stop ...g \tabl_ntb_flush_content
> }\ifcase
> \tabl_ntb_get_gal...
> \eTABLE ...oveunwantedspaces \tabl_ntb_table_stop
> \stopTBLprocessing \fi
> \po...
> l.147 \eTABLE
>
> ...
> l.12 ...ary}{Week}}{\getvariable{PocketDiary}{Year}}
>
>
>
>
>
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
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### Re: [NTG-context] placefigure and listoffigures
I would define another float and assign this not to be listed float to this new
float-type something like \definefloat[Notlisted][figure] and then
\startplaceNotlisted
\externalf…
\stopplaceNotlisted
Best wishes
Willi
> On 15 mrt. 2016, at 21:43, Alan BRASLAU wrote:
>
> Hi,
>
> How can one suppress the addition of a placed figure to the
> listoffigures?
>
> In the following MWE, list=no places "no" as an alternative to the
> (blank) title.
>
> Alan
>
>
> \starttext
>
> \startplacefigure [location=inmargin,number=no,list=no]
> \externalfigure [cow] [width=1cm]
> \stopplacefigure
> \input knuth
>
> \blank
>
> \placelistoffigures [criterium=all]
>
> \stoptext
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive : http://foundry.supelec.fr/projects/contextrev/
> wiki : http://contextgarden.net
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___
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### Re: [NTG-context] Struggling with new version of ConTeXt
Hans, thank you for fixing this so quickly!
Willi
> On 4 mrt. 2016, at 10:42, Hans Hagen <[email protected]> wrote:
>
> On 3/4/2016 6:03 AM, Willi Egger wrote:
>> With version :ConTeXt ver: 2016.02.17 11:11 MKIV beta the following code
>> worked:
>>
>> \define[2]\Illustration{%
>> \startplacefigure
>> [title=#2,reference=fig:#1]
>> \externalfigure[#1][height=.25\textheight]
>> \stopplacefigure}
>>
>> \starttext
>>
>> \Illustration{cow}{A Frisian cow}
>>
>> \stoptext
>>
>> With ConTeXt ver: 2016.03.03 23:31 MKIV beta I get a fatal error:
>>
>> ...test.tex: ! Extra }, or forgotten \endgroup
>>
>> \strc_counters_register_component_list ...focus
>> }}titledata{label{\detokeniz...
>> \strc_counters_register_component ...}{#3}{#4}{#9}\else \ifx
>> \currentstructu...
>> \strc_floats_place_packaged_boxes_indeed ... ][#1]\globallet
>> \previousfloatn...
>> \strc_floats_finish_placement ...e_packaged_boxes\dostoptagged \global
>> \d_p...
>> l.30 \Illustration{cow}{A Frisian cow}
>
> fixed, btw you can also say:
>
> \starttexdefinition Illustration #1#2
>\startplacefigure[title=#2,reference=fig:#1]
>\externalfigure[#1][height=.25\textheight]
>\stopplacefigure
> \stoptexdefinition
>
>
>
>
> -
> Hans Hagen | PRAGMA ADE
> Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
> tel: 038 477 53 69 | www.pragma-ade.com | www.pragma-pod.nl
> -
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive : http://foundry.supelec.fr/projects/contextrev/
> wiki : http://contextgarden.net
> ___
___
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### Re: [NTG-context] \writetolist command...
Hans, thank you for your tip!
Willi
> On 4 mrt. 2016, at 12:08, Hans Hagen <[email protected]> wrote:
>
> On 3/4/2016 5:37 AM, Willi Egger wrote:
>> Hi all,
>>
>> I need to write to a list, however it appears that the second argument from
>> \writetolist[name]{number}{ext} does not end up in the list. — What do I
>> miss?
>>
>> \starttext
>> \startsubject[title=Contents]
>> \placelist[section][criterium=all]
>> \stopsubject
>>
>> \startsubject[title=A Paragraph as Subject]
>> \writetolist[section]{1}{Writetolist: Subject title}
>> \stopsubject
>> \stoptext
>
>
>
> -
> Hans Hagen | PRAGMA ADE
> Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
> tel: 038 477 53 69 | www.pragma-ade.com | www.pragma-pod.nl
> -
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive : http://foundry.supelec.fr/projects/contextrev/
> wiki : http://contextgarden.net
> ___
___
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### [NTG-context] Struggling with new version of ConTeXt
With version :ConTeXt ver: 2016.02.17 11:11 MKIV beta the following code
worked:
\define[2]\Illustration{%
\startplacefigure
[title=#2,reference=fig:#1]
\externalfigure[#1][height=.25\textheight]
\stopplacefigure}
\starttext
\Illustration{cow}{A Frisian cow}
\stoptext
With ConTeXt ver: 2016.03.03 23:31 MKIV beta I get a fatal error:
...test.tex: ! Extra }, or forgotten \endgroup
\strc_counters_register_component_list ...focus }}titledata{label{\detokeniz...
\strc_counters_register_component ...}{#3}{#4}{#9}\else \ifx \currentstructu...
\strc_floats_place_packaged_boxes_indeed ... ][#1]\globallet \previousfloatn...
\strc_floats_finish_placement ...e_packaged_boxes\dostoptagged \global \d_p...
l.30 \Illustration{cow}{A Frisian cow}
Kind regards
Willi
___
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___
### [NTG-context] \writetolist command...
Hi all,
I need to write to a list, however it appears that the second argument from
\writetolist[name]{number}{ext} does not end up in the list. — What do I miss?
\starttext
\startsubject[title=Contents]
\placelist[section][criterium=all]
\stopsubject
\startsubject[title=A Paragraph as Subject]
\writetolist[section]{1}{Writetolist: Subject title}
\stopsubject
\stoptext
Kind regards
Willi
___
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### Re: [NTG-context] goto
Hello Hans,
In the past, that is in the pdfTeX time, I used this feature as follows:
\starttext
\stoptext
I tested it with a recent version of MKIV and it works.
Willi
On 18 okt. 2015, at 11:49, Meer, Hans van der wrote:
>
> I would like to be able to go directly to a local document by an interaction
> statement. The \goto command seems to be meant for this.
> However, the descriptions in the command reference and the Wiki do not
> explain all of its parameters:
> In \goto{1}{2}[3] parameters 1 and 2 are marked CONTEXT and 3 is marked
> REFERENCE. I could find parameter {1} typeset in the text and [3] as the
> reference in for example a \placefigure.
>
> What is {2} supposed to do? \goto{}Something}[] does not places Something to
> find.
>
> I tried to effect the jump to a document on my system with
> \goto{local-doc}[/Volumes/Users/myhome/Documents/myfigure.jpg]
> but this does not works as I hoped.
>
> How to?
>
> Hans van der Meer
>
>
>
>
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
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> archive : http://foundry.supelec.fr/projects/contextrev/
> wiki : http://contextgarden.net
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### [NTG-context] Fonts... bold smallcaps
Hi all,
sorry for bothering you with this.
I have a font Seravek-Regular.otf and Seravek-Bold.otf. It is actually my
company font.
Now I needed to use bold-smallcaps. But I can not get it working, though
otfinfo tells, that in the bold font there are smallcaps
In my typescript file I have the following two lines, from which the Regular
variant works perfectly well.
\definefontsynonym [SansCaps] [Seravek-Regular]
[features=smallcaps]
\definefontsynonym [SansBoldCaps] [Seravek-Bold]
[features=smallcaps]
I tried to get bold smallcaps with \bf\sc but without success.
Can anyone point me what to do?
Kind regards
Willi
___
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___
### Re: [NTG-context] Fonts... bold smallcaps
Wolfgang and Taco,
thank you for this!
Tac, the font Seravek I have is a bought font from processtype.
Willi
> On 8 okt. 2015, at 12:24, Taco Hoekwater <[email protected]> wrote:
>
>>
>> On 08 Oct 2015, at 12:09, Wolfgang Schuster <[email protected]>
>> wrote:
>>
>>> Willi Egger 8. Oktober 2015 um 11:40
>>> Hi all,
>>>
>>> sorry for bothering you with this.
>>>
>>> I have a font Seravek-Regular.otf and Seravek-Bold.otf. It is actually my
>>> company font.
>>>
>>> Now I needed to use bold-smallcaps. But I can not get it working, though
>>> otfinfo tells, that in the bold font there are smallcaps
>>>
>>> In my typescript file I have the following two lines, from which the
>>> Regular variant works perfectly well.
>>>
>>> \definefontsynonym [SansCaps] [Seravek-Regular] [features=smallcaps]
>>> \definefontsynonym [SansBoldCaps] [Seravek-Bold] [features=smallcaps]
>>>
>>> I tried to get bold smallcaps with \bf\sc but without success.
>
> SansBoldCaps does not have a ‘short form’, afaik.
>
>>> Can anyone point me what to do?
>> \bf\setsmallcaps
>
> (or \let\sc\setsmallcaps, somewhere in the setup section, which is what I
> usually do).
>
> Note that this method does not need nor use the SansCaps and SansBoldCaps
> synonyms in the typescript, and that it only works for well-behaved opentype
> fonts. Oh, and it may give you italic smallcaps, something the old ’SansCaps’
> based method never did.
>
> Best wishes,
> Taco
>
>
>
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
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> archive : http://foundry.supelec.fr/projects/contextrev/
> wiki : http://contextgarden.net
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___
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### [NTG-context] \setupitemgroup...
Hi all,
I tried to setup itemization on three levels. However I do not get the desired
result. The setup does not make level one numbered, level two a-b-c and level
three with center-dot.
What am I missing?
Kind regards
Willi
\setupitemgroup
[itemize]
[1]
[packed]
[n,after=]
\setupitemgroup
[itemize]
[2]
[packed]
[a,after=]
\setupitemgroup
[itemize]
[3]
[packed,after=]
[1]
\starttext
\startitemize
\startitem
Level 1
\startitemize
Level 2
\stopitemize
\startitemize
Level 2
\startitemize
\startitem
Level 3
\stopitem
\startitem
Level 3
\stopitem
\stopitemize
\stopitemize
\stopitem
\startitem
Level 1
\stopitem
\stopitemize
More text \dots
\stoptext
___
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___
### Re: [NTG-context] \setupitemgroup...
Wolfgan and Otared,
thanks! - stupid me, this version i had before, but then I concentrated on the
level two and messed it up.
It appears, that the level two does not accept any symbol like 1,r,a.
Kind regards
Willi
> On 7 okt. 2015, at 11:45, Wolfgang Schuster
> wrote:
>
>> Otared Kavian 7. Oktober 2015 um 11:27
>> Hi Wolfgang and Willi,
>>
>> Indeed the observation made by Wolfgang is correct, but even upon following
>> those instructions, somehow the level 2 does not work as expected:
>>
> You forgot the \item for the second level entries.
>
> Wolfgang
> ___
> If your question is of interest to others as well, please add an entry to the
> Wiki!
>
> maillist : [email protected] / http://www.ntg.nl/mailman/listinfo/ntg-context
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___
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### Re: [NTG-context] \setupitemgroup...
Hi Otared and Wolfgang,
Gosh! Indeed, my structure was amiss. Sorry for the noise and thank you for
pointing this out to me!
Kind regards
Willi
> On 7 okt. 2015, at 12:36, Otared Kavian wrote:
>
> \starttext
> \startitemize
> \startitem
> Level 1
> \startitemize
> \startitem
> Level 2
> \stopitem
> \startitem
> Level 2
> \stopitem
> \startitemize
> \startitem
> Level 3
> \stopitem
> \startitem
> Level 3
> \stopitem
> \stopitemize
> \stopitemize
> \stopitem
> \startitem
> Level 1
> \stopitem
> \stopitemize
> More text \dots
> \stoptext
___
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___
### Re: [NTG-context] Struggling with alignment inside tabulate...
Hi Wolfgang!
Thank you so much for this!
Willi
On 6 aug. 2015, at 23:56, Wolfgang Schuster [email protected]
wrote:
Willi Egger 6. August 2015 23:47
Hi all,
what kind of trickry is necessary to get the following minimal example to
give correct output? As given it generates a single line out of the itemize
part…
You need a p (paragraph) column.
Kind regards
Will
\starttext
\starttabulate[|l|r|r|]
\starttabulate[|l|r|p|]
Wolfgang
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### [NTG-context] Struggling with alignment inside tabulate...
Hi all,
what kind of trickry is necessary to get the following minimal example to give
correct output? As given it generates a single line out of the itemize part…
Kind regards
Will
\starttext
\starttabulate[|l|r|r|]
\NC \strut \NC {\bf Rohmass} \NC {\bf Fertigmass} \NC\NR
\NC Höhe Mittelteil \NC -- \NC \unit{12 milli meter}\NC\NR
\NC Höhe bei den Enden \NC -- \NC Vor dem Einleimen: \par
\startitemize
\startitem
Enden \unit{8.5 milli meter}
\stopitem
\startitem
Mitte innen: \unit{16.5 milli meter}
\stopitem
\stopitemize\par
\NC\NR
\stoptabulate
\stoptext
___
`
|
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9040617942810059, "perplexity": 14304.15654736784}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-04/segments/1610703505861.1/warc/CC-MAIN-20210116074510-20210116104510-00616.warc.gz"}
|
http://www.parabola.unsw.edu.au/2010-2019/volume-52-2016/issue-3/article/problems-section-problems-1511-1520
|
# Problems Section: Problems 1511--1520
Q1511 In a certain country (see Q1494 and Q1502), between every pair of towns there is a highway going in one direction but not in the other direction. A town is called central'' if it can be reached from every other town either directly, or with just one intermediate town.
(a) Show that if there are 8 towns in this country, then it is possible for every town to be central.
(b) Show that the same is true for any number of towns except 2 or 4.
|
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7849558591842651, "perplexity": 510.9767174832937}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-26/segments/1498128320209.66/warc/CC-MAIN-20170624013626-20170624033626-00122.warc.gz"}
|
http://banubula.blogspot.com/2007_07_01_archive.html
|
## Sunday, July 01, 2007
### The Broken Mirror: III
Building better Mirrors
The fall of Parity triggered the question: If our Universe does not obey simple mirror-symmetry, then what kind of symmetry does it obey? In other words, perhaps we were looking in the wrong mirror.
P-symmetry is a mirror of parity, reversing left and right. We can think of it also as a transformation: It is an exchange of every Left-handed interaction with a Right-handed interaction.
C-Symmetry
Let's consider other types of mirrors. Physicists also examined another mirror called C-symmetry, or Charge symmetry. C Symmetry is a mirror which exchanges every positively charged particle with a negatively charged particle. In the world of physics this essentially means that the C mirror transforms particles into anti-particles and vice-versa. A proton and electron become an anti-proton and a positron.
So, what happens when we use the C Mirror, when we swap particles for anti-particles? Do the anti-particles obey the same laws of physics? The answer is No. C-symmetry is not a property of this Universe.
T-symmetry
Ok, let's consider another abstract mirror. What if we take all particles and interactions in the Universe and move them backwards? Shown a film of a particle interaction, can we tell whether the film had been reversed? (Note to all clever folks: This is not the same as the question addressed by the Second Law since that applies only to macroscopic systems.)
Is our Universe symmetric in Time? This question is known as that of T-symmetry. The answer is...mostly yes. That is, we cannot detect a reversed film unless it contains some particular time-asymmetric interactions. This all comes down to the interactions of one particle: The Kaon. I summarize here from a physics abstract:
Most fundamental physical processes are symmetric in time. The motion of the planets in the gravity field of the sun is reversable- a film of the motion of a planet around its sun can be shown backwards without anyone being able to tell. Similarly to gravity, the strong nuclear and electromagnetic forces are also time-symmetric. Only the weak nuclear force appears to violate this symmetry, and this so far only in the behavior of the neutral kaon.
Combining symmetries
If I reflect a mirror image of a mirror image, I get the original. Mirrors can be combined to produce more mirrors.
The failure of P and C and T symmetry in our Universe is confounding. Recall that P symmetry is closest to what we consider a classic mirror, reversing left and right. What if we combine two mirrors (or more), combining the C mirror with the P mirror?
What this means in practice is that the mirror on the wall does show a valid Universe if we also exchange particles for anti-particles. The resulting symmetry is known as CP symmetry.
In 1980, James Cronin and Val Fitch earned the Nobel prize in physics for demonstrating that CP symmetry is not conserved. It was mostly conserved but violated in some interactions of the Kaon.
CPT: the Ultimate Mirror
The CP violation of the Kaon and the T violation of the Kaon are in fact related. They can be canceled out by throwing togther CP and T to make CPT: antiparticles in a mirror going backwards in time.
There is every reason to believe that CPT symmetry holds for our Universe. Even the Kaon (so far) obeys CPT symmetry. But what exactly does CPT symmetry imply? And what makes the Kaon such an anomaly?
|
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http://aas.org/archives/BAAS/v35n5/aas203/410.htm
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AAS 203rd Meeting, January 2004
Session 11 Planetary Nebulae
Poster, Monday, January 5, 2004, 9:20am-6:30pm, Grand Hall
## [11.05] An Infrared Survey of Neutron-Capture Elements in Planetary Nebulae
N. C. Sterling, H. L. Dinerstein (University of Texas)
We present results from an ongoing survey of the infrared emission lines [Kr III] 2.199 and [Se IV] 2.287 \mum, first identified by Dinerstein (2001, ApJ, 550, L223), in planetary nebulae (PNe). Isotopes of Se (Z=34) and Kr (Z=36) are created by the slow neutron-capture process (\emph{s}-process) during the asymptotic giant branch (AGB) phase, and may be brought to the stellar envelope by third dredge-up (TDU). Therefore, PNe will be enriched in \emph{n}-capture elements if efficient TDU occurred in the progenitor star. Since intermediate-mass stars are the source of a significant fraction of the \emph{s}-process isotopes in the Galaxy (via TDU), measurement of \emph{n}-capture element abundances in PNe is of vital importance for models of Galactic chemical evolution. Using CoolSpec (Lester et al. 2000, PASP, 112, 384) on the 2.7-m Harlan J. Smith telescope at McDonald Observatory, we have observed 49 PNe and detected [Kr III] and/or [Se IV] in 27. The high detection rate demonstrates that these two lines are measurable in a significant fraction of Galactic PNe. We use the ionization correction factors Se3+/Se~\approx~Ar++/Ar and Kr++/Kr~\approx~S++/S to derive total elemental abundances, and find that the Kr and Se abundances vary widely among the studied PNe, from roughly solar to overabundant by a factor of 10. This indicates that the efficiency of TDU differed significantly among our sample's progenitor stars. We compare the derived Kr and Se abundances to other nebular properties to search for correlations. Our initial results lend support to the suggestion of Sterling, Dinerstein, & Bowers (2002, ApJ, 578, L55) that \emph{n}-capture element abundances are larger in PNe with Wolf-Rayet ([W-R]) central stars than those without. This is believed to be due to the heavy mass loss and/or deep mixing which these stars experienced as they evolved into H-poor, C-rich [W-R] stars.
This research is supported by NSF grant AST 97-31156.
Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.
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http://physics.stackexchange.com/questions?page=3&sort=active
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# All Questions
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http://www.gradesaver.com/tucker-the-man-and-his-dream/wikipedia/background
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Tucker: The Man and His Dream Francis Ford Coppola
Background
From childhood, Coppola envisioned a film about the Tucker automobile[2] and while attending the UCLA School of Theater, Film and Television in the early 1960s, further refined a film concept based on the life of Preston Tucker.[3] In June 1973, during the filming of The Godfather Part II (1974), Coppola announced his intention to start development at American Zoetrope as writer, producer and director. He had already approached Marlon Brando for the lead role.[4] He then purchased the rights from the Tucker Estate in 1976,[5] and, in addition to Brando, discussed the leading role with Jack Nicholson[6] and also considered Burt Reynolds.[7] Taking inspiration from Citizen Kane (1941), Kabuki theater and the work of Bertolt Brecht, Coppola initially planned to make Tucker as a "dark kind of musical."[3] He later said that the idea approximated the style of an experimental film,[8] similar to Mishima: A Life in Four Chapters (1985), which he produced.[3]
The musical would have featured Tucker predominantly, but storylines would have interwoven Thomas Edison, Henry Ford, Harvey Samuel Firestone and Andrew Carnegie as supporting characters. Leonard Bernstein agreed to write the music, and Betty Comden and Adolph Green were hired to write the lyrics. They all spent a week at Coppola's home in California,[5] planning the musical which resulted in Bernstein writing one song.[8] Coppola also approached Gene Kelly as a consultant for the dance choreography.[4] However, financing for Tucker fell through when Coppola's production company, American Zoetrope, filed for bankruptcy after the box office failures of One from the Heart (1982) and The Cotton Club (1984).[3][9] Coppola abandoned Tucker for the time being and went to work on Peggy Sue Got Married (1986).[5]
In 1986,[5] during the production of Captain EO (1986),[10] Coppola's friend George Lucas encouraged him to revive development for Tucker, believing it to be "the best film Francis had ever been involved with."[5] In addition, Lucas agreed to serve as executive producer and offered the use of his filmmaking companies, Lucasfilm and Industrial Light & Magic.[10] He also convinced Coppola to drop the musical idea in favor of doing a homage to the films of Frank Capra, especially Mr. Smith Goes to Washington (1939).[5] Coppola became interested in the American Dream aspect of the storyline, as well as post-World War II capitalism and politics.[8] At one point, Coppola approached Capra to produce the film with Lucas, however, Capra thought Tucker was a failure and Coppola dropped that plan.[7]
Coppola originally intended to write the screenplay himself, but due to his commitment to the filming of Gardens of Stone (1987), engaged Arnold Schulman who scripted Capra's A Hole in the Head (1959). Schulman eventually collaborated with David Seidler on the Tucker project.[3] Subsequently, Coppola rewrote the Schulman and Seidler scripts, but an attempt to get a co-writing credit on the film was overruled by the Writers Guild of America, as an arbitration committee determined Coppola did not contribute enough to the script to warrant an on-screen writing credit.[4] The filmmakers devised a $24 million production budget, but Universal Pictures, Walt Disney Pictures, TriStar Pictures and Paramount Pictures wanted Coppola and Lucas to lower it to$15 million. Distributors were also dubious about working with Lucas after the 1986 commercial and critical failures of both Labyrinth[7] and Howard the Duck.[3] Lucas decided to cover the \$24 million budget himself, and pre-production proceeded.[5]
This content is from Wikipedia. GradeSaver is providing this content as a courtesy until we can offer a professionally written study guide by one of our staff editors. We do not consider this content professional or citable. Please use your discretion when relying on it.
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http://mathhelpforum.com/algebra/197898-understanding-factoring.html
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# Math Help - Understanding this for factoring
1. ## Understanding this for factoring
Factor completly:
(3n-1)2 - (3n-1) - 72
What do you use to process this? If there is nothing to work with the -72? You can factor out (3n-1) correct? But still left with the -72?
2. ## Re: Understanding this for factoring
Originally Posted by Kibbygirl
Factor completly:
(3n-1)2 - (3n-1) - 72
$x^2-x-72=(x-9)(x+8)$. Let $x=3n-1.$
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http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=JGGHBA_2015_v36n7_661
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UBVI CCD Photometry of NGC 7790
Title & Authors
UBVI CCD Photometry of NGC 7790
Choi, Dong Yeol; Kim, Hee Soo; Lim, Beomdu; Sung, Hwankyung;
Abstract
UBVI CCD photometry of the intermediate age open cluster NGC 7790 has been obtained using AZT-22 1.5 m telescope (f/7.74) at the Maidanak Astronomical Observatory in Uzbekistan. NGC 7790 contains three $\small{{\delta}}$ Cep variable stars including CEa Cas, CEb Cas, and CF Cas. PSF photometry was carried out using IRAF/DAOPHOT for all observations. The total number of stars observed both in V and I filter was 1008 and the limiting magnitude was $\small{V{\approx}22}$. To determine atmospheric extinction coefficients and photometric zero points, many blue and red standard stars as well as the standard stars in the celestial equator under various airmass were observed. Photometric data were transformed into the standard Johnson-Cousins' UBVI standard system. From the analysis of UBVI color-magnitude diagram and color-color diagram, the color excess in V and I filter [$\small{E(B-V)=0.58{\pm}0.02}$], the selective extinction ratio in V and I filter [$\small{R_V{\equiv}A_V/E(B-V)=3.02{\pm}0.09}$] and distance modulus ($\small{V_0-M_V=12.65{\pm}0.10}$) of the cluster were determined. The age of the cluster was estimated to be log $\small{age=8.05{\pm}0.05}$ [yr] based on the position of these three Cepheid variables in the color-magnitude diagram, the isochrone of the Geneva group ($\small{Ekstr{\ddot{o}}m}$ et al., 2012-Z=0.019), and the isochrone of the Padova group (Bressan et al., 2012-Z=0.014) were used to compare each other. Of them, the Geneva models that considered stellar rotation well described the position of $\small{{\delta}}$ Cepheid variables in the blue loop. Although they were well consistent with standard period-luminosity relation of $\small{{\delta}}$ Cepheid variables, three Cepheid variables in NGC 7790 were, on average, brighter by about 0.5 mag than the absolute magnitude estimated from the mean period-luminosity relation at a given period.
Keywords
ngc 7790;UBVI;the color-magnitude diagram;$\small{{\delta}}$ Cepheid variables;the period-luminosity relation;
Language
Korean
Cited by
References
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Alcala, J.M. and Ferro, A.A., 1988, UBVRI photoelectric photometry of the open cluster NGC 7790. Revista Mexicana Astronomia Astrofisica, 16, 81-86.
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Lim, B.D., Sung H.K., Bessell M.S., Karimov, R., and Ibrahimov, M., 2009, CCD photometry of standard stars at Maidanak astronomical observatory in Uzbekstan: transformations and comparisons. Journal of The Korean Astronomical Society, 42, 161-174.
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Romeo, G., Bonifazi, A., Pecci, F.F., and Tosi, M., 1989, CCD photometry of galacitc open clusters-I. NGC 7790. Monthly Notices of the Royal Astronomical Society, 240, 459-485.
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Sandage, A., 1958, Cepheids in galactic clusters. I. CF Cass in NGC 7790. The Astrophysical Journal, 128, 150-160.
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Sandage, A. and Tammann, G.A., 1969, The double Cepheid CE cassiopeiae in NGC 7790: Tests of the theory of the instability strip and the calibration of the period-luminosity-color relation. The Astrophysical Journal, 157, 683-708.
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Schmidt, E.G., 1981, Four-color and $H{\beta}$ photometry of the galactic cluster NGC 7790. The Astronomical Journal, 86, 242-245.
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Sung, H. and Bessell, M.S., 1999, UBVI CCD photometry of M35 (NGC 2168). Monthly Notices of the Royal Astronomical Society, 306, 361-370.
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Sung, H., Bessell, M.S., Lee, H.W., Kang, Y.H., and Lee, S.W., 1999, UBVI CCD photometry of M11-2. New photometry and surface density profiles. Monthly Notices of the Royal Astronomical Society, 310, 982-1001.
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|
https://open.library.ubc.ca/cIRcle/collections/48630/items/1.0347363
|
# Open Collections
## BIRS Workshop Lecture Videos
### Clustering Implies Geometry in Networks Krioukov, Dmitri
#### Description
Two common features of many large real networks are that they are sparse and that they have strong clustering, i.e., large number of triangles homogeneously distributed across all nodes. In many growing real networks for which historical data is available, the average degree and clus- tering are roughly independent of the growing network size. Recently, (soft) random geometric graphs, also known as latent-space network models, with hyperbolic and de Sitter latent geome- tries have been used successfully to model these features of real networks, to predict missing and future links in them, and to study their navigability, with applications ranging from designing optimal routing in the Internet, to identification of the information-transmission skeleton in the human brain. Yet it remains unclear if latent-space models are indeed adequate models of real networks, as random graphs in these models may have structural properties that real networks do not have, or vice versa. We show that the canonical maximum-entropy ensemble of random graphs in which the expected numbers of edges and triangles at every node are fixed to constants, are approximately soft random geometric graphs on the real line. The approximation is exact in the limit of standard random geometric graphs with a sharp connectivity threshold and strongest clustering. This result implies that a large number of triangles homogeneously distributed across all vertices is not only necessary but also a sufficient condition for the presence of a latent/effective metric space in large sparse networks. Strong clustering, ubiquitously observed in real networks, is thus a reflection of their latent geometry.
|
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https://www.mikaelsand.se/2022/01/
|
# Month: January 2022
Bicep is a very nice language that rests on top of ARM. I have always preferred ARM to scripting as “wanted state” is a much better way of looking at anything relating to infrastructure.
But this reliance on ARM also means that whatever template definition is output by the product, that is what you must use. Case in point: Azure Front Door.
# Circular reference
A circular reference in an age old problem in coding. You cannot use circual references because, logically, it does not work. It is a series of references where the last object references the first, resulting in a closed loop.
Within Azure Front Door (or AFD) we have this problem, a lot. Within AFD it refers to itself, and if you add a Rules Engine (RE), that refers to the AFD, that refers to the RE.
If you do like I do: Setup something the first time using the portal, and the extract the ARM using the Export Template, or Insert Resource in VS Code to get the Bicep Code directly, you will find that the generated ARM contains a lot of errors due to circular references.
We need to overcome this, and solve some other issues.
## The first problem
The first problem comes about 5 rows in, when we need to define the (first) routing rule. You need to assign it an ID. This ID consist of the resource ID for the AFD that we are just about to create!
This is the first of many circular references.
### The solution
I solved this, and all other circular references, by using variables and string interpolation. Simply put: Create the resource ID yourself. You know what the ID will be, because you are just about to create it.
Create two useful variables at the top of the bicep file.
var frontDoorName = 'contoso-afd-test'
var frontDoorResourceId = '{resourceGroup().id}/providers/Microsoft.Network/frontDoors/{frontDoorName}'
You must deploy the AFD within the context of a resource group, even if the AFD is a global service. You get the start of the resource ID by reffering to this, and the add the rest. The resulting frontDoorResourceId would be:
/subscriptions/GUIDHERE/resourcegroups/contoso-TEST-rg/providers/Microsoft.Network/frontdoors/contoso-afd-test
Now, we can use the frontDoorResourceId variable, every time a sub-resource needs to be defined, such as a routing rule or backend pool, as defined below.
routingRules: [
{
id: '{frontDoorResourceId}/RoutingRules/APIm'
name: 'APIm'
properties: {
routeConfiguration: {
forwardingProtocol: 'HttpsOnly'
backendPool: {
id: '{frontDoorResourceId}/BackendPools/ApimEurope${Env}' } '@odata.type': '#Microsoft.Azure.FrontDoor.Models.FrontdoorForwardingConfiguration' } ... } } ] ## The second problem The next problem is the rules engines. In the template definition it looks like you need to add another Resource ID, but there is a problem. The Rules Engines is a totally different resource type and it needs to be created separately. This means you simply cannot refer to it in the same way as with the frontDoorResourceId above. ### The solution It is very easy: Do not add the property to the AFD Definition. This property is not read only, but it will be assigned at deploy time by the Rules Engines Definition you add to the same Bicep File. resource frontDoorRulesEngine 'Microsoft.Network/frontDoors/rulesEngines@2020-05-01' = { name: rulesEngineName parent: frontDoor properties: { rules: [ { name: 'RuleNumberOne' priority: 0 action: { routeConfigurationOverride: { forwardingProtocol: 'HttpsOnly' backendPool: { id: '${frontDoorResourceId}/BackendPools/FightClub'
}
'@odata.type': '#Microsoft.Azure.FrontDoor.Models.FrontdoorForwardingConfiguration'
}
}
...
// Rule settings go here
...
}
]
}
}
You assign the AFD you are about to create as the rules engine’s parent. This will connect the AFD and the RE at deploytime.
Note the use of the frontDoorResourceId to refer to the Backend Pool.
## The third (last) problem
The this is only a problem if you are using the Web Application Firewall (WAF) and you should. If you need to enable the WAF you must refer to a policy, or rather a FrontDoorWebApplicationFirewallPolicies resource. You do this when you create your frontendEndpoints.
### A solution
This is not the solution, but I know it works for me. I define the WAF policies in a separate Bicep file as these tend to be separate from the Front Door. Remember, you can reuse the same policy for different WAFs.
Create a separate file with the resource definition. If you want to send a customized error message you need to run the base64 string function on it before deployment. This is much more useful than converting it to Base64 and pasting that sting into the Bicep-file.
Name the policy using a parameter.
param PolicyName string
resource defaultPolicy 'Microsoft.Network/FrontDoorWebApplicationFirewallPolicies@2020-11-01' = {
name: PolicyName
policySettings: {
enabledState: 'Enabled'
mode: 'Prevention'
customBlockResponseStatusCode: 406
customBlockResponseBody: base64('<html><head><title>You are blocked</title></head><body bgcolor="#FFB299"><p><h1>WAF custom response</h1>You are being blocked. If you need access, contact support with this reference{{azure-ref}}</p></body></html>')
}
}
Send the policy name parameter to your AFD bicep and construct the reference using string interpolation. My naming below assumes that the policy is deployed in the same resource group as the AFD. If that is not your case, create a reference to that resource group in the bicep file, or update your bicep file for the policy to use an output parameter and send that to the AFD bicep deployment.
About the error message and the use of azure-ref, consult this documentation.
output policyResourceID string = myPolicy.id
This is how I constructed the resource reference in my AFD Bicep file. Note the liberal use of the frontDoorResourceId and frontDoorName variables.
frontendEndpoints: [
{
id: '{frontDoorResourceId}/FrontendEndpoints/{frontDoorName}-azurefd-net'
name: '{frontDoorName}-azurefd-net'
properties: {
hostName: '{frontDoorName}.azurefd.net'
sessionAffinityEnabledState: 'Enabled'
sessionAffinityTtlSeconds: 0
|
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|
https://stackabuse.com/working-with-pdfs-in-python-inserting-deleting-and-reordering-pages/
|
## Working with PDFs in Python: Inserting, Deleting, and Reordering Pages
### Introduction
This article is part three of a little series on working with PDFs in Python. In the previous articles we gave an introduction into reading PDF documents using Python. So far you have learned how to manipulate existing PDFs, and to read and extract the content - both text and images. Furthermore, we have discussed splitting documents into its single pages, as well as adding watermarks and barcodes.
Now in this article we will go one step further and demonstrate how to rearrange a PDF document in a few different ways.
### Deleting Pages with pdfrw
Deleting individual pages from a PDF file is as simple as the following:
• Read a PDF as an input file
• Write selected pages to a new PDF as an output file
The following example removes the first two pages from a PDF document. Using the pdfrw library, the file is read with the help of the PdfReader() class first. Except for both the first and second page, each page is added to the output file using the addpage() method, and then written to disk eventually.
Figure 1 shows the output when executing the code on a four-page PDF file.
# !/usr/bin/python
# Remove the first two pages (cover sheet) from the PDF
input_file = "example.pdf"
output_file = "example-updated.pdf"
# Define the reader and writer objects
writer_output = PdfWriter()
# Go through the pages one after the next
if current_page > 1:
print("adding page %i" % (current_page + 1))
# Write the modified content to disk
writer_output.write(output_file)
### Deleting Pages with PyMuPDF
The PyMuPDF library comes with quite a few sophisticated methods that simplify deleting pages from a PDF file. It allows you to specify either a single page (using the deletePage() method), or a range of page numbers (using the deletePageRange() method), or a list with the page numbers (using the select() method).
The following example will demonstrate how to use a list in order to select the pages to keep from the original document. Be aware that the pages that are not specified will not be part of the output document. In our case the output document contains the first, second, and fourth pages only.
# !/usr/bin/python
# Recall that PyMuPDF is imported as fitz
import fitz
input_file = "example.pdf"
output_file = "example-rearranged.pdf"
# Define the pages to keep - 1, 2 and 4
file_handle = fitz.open(input_file)
pages_list = [0,1,3]
# Select the pages and save the output
file_handle.select(pages_list)
file_handle.save(output_file)
### Inserting Pages with PyMuPDF
The PyMuPDF library allows you to insert pages as well. It provides the methods newPage() for adding completely blank pages, and insertPage() in order to add an existing page. The next example shows how to add a page from a different PDF document at the end of another one.
# !/usr/bin/python
# Recall that PyMuPDF is imported as fitz
import fitz
original_pdf_path = "example.pdf"
extra_page_path = "extra-page.pdf"
output_file_path = "example-extended.pdf"
original_pdf = fitz.open(original_pdf_path)
extra_page = fitz.open(extra_page_path)
original_pdf.insertPDF(extra_page)
original_pdf.save(output_file_path)
### Splitting Even and Odd Pages with PyPDF2
The following example uses PyPDF2 and does this by taking a file, separating it into its even and odd pages, saving the even pages in the file even.pdf, and the odd pages in odd.pdf.
This Python script starts with the definition of two output files, even.pdf and odd.pdf, as well as their corresponding writer objects pdf_writer_even and pdf_writer_odd. Next, in a for-loop the script goes through the entire PDF file, and reads one page after the other. Pages with even page numbers are added to the stream pdf_writer_even using addPage(), and odd numbers are added to the stream pdf_writer_odd. At the end the two streams are saved to disk in separate files, as defined before.
#!/usr/bin/python3
pdf_document = "example.pdf"
# Output files for new PDFs
output_filename_even = "even.pdf"
output_filename_odd = "odd.pdf"
pdf_writer_even = PdfFileWriter()
pdf_writer_odd = PdfFileWriter()
# Get reach page and add it to corresponding
# output file based on page number
for page in range(pdf.getNumPages()):
current_page = pdf.getPage(page)
if page % 2 == 0:
else:
# Write the data to disk
with open(output_filename_even, "wb") as out:
pdf_writer_even.write(out)
print("created", output_filename_even)
# Write the data to disk
with open(output_filename_odd, "wb") as out:
pdf_writer_odd.write(out)
print("created", output_filename_odd)
### Conclusion
Re-writing and re-arranging the structure of a PDF is fairly easy with the libraries pdfrw, PyMuPDF, and PyPDF2. With just a few lines of Python code you can delete pages, separate them, and add new content.
|
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|
https://nips.cc/Conferences/2016/ScheduleMultitrack?event=6227
|
`
Timezone: »
Workshop
Adaptive and Scalable Nonparametric Methods in Machine Learning
Aaditya Ramdas · Arthur Gretton · Bharath Sriperumbudur · Han Liu · John Lafferty · Samory Kpotufe · Zoltán Szabó
Fri Dec 09 11:00 PM -- 09:30 AM (PST) @ Room 120 + 121
Large amounts of high-dimensional data are routinely acquired in scientific fields ranging from biology, genomics and health sciences to astronomy and economics due to improvements in engineering and data acquisition techniques. Nonparametric methods allow for better modelling of complex systems underlying data generating processes compared to traditionally used linear and parametric models. From statistical point of view, scientists have enough data to reliably fit nonparametric models. However, from computational point of view, nonparametric methods often do not scale well to big data problems.
The aim of this workshop is to bring together practitioners, who are interested in developing and applying nonparametric methods in their domains, and theoreticians, who are interested in providing sound methodology. We hope to effectively communicate advances in development of computational tools for fitting nonparametric models and discuss challenging future directions that prevent applications of nonparametric methods to big data problems.
We encourage submissions on a variety of topics, including but not limited to:
- Randomized procedures for fitting nonparametric models. For example, sketching, random projections, core set selection, etc.
- Nonparametric probabilistic graphical models
- Scalable nonparametric methods
- Multiple kernel learning
- Random feature expansion
- Novel applications of nonparametric methods
- Bayesian nonparametric methods
- Nonparametric network models
This workshop is a fourth in a series of NIPS workshops on modern nonparametric methods in machine learning. Previous workshops focused on time/accuracy tradeoffs, high dimensionality and dimension reduction strategies, and automating the learning pipeline.
Fri 11:30 p.m. - 12:00 a.m. Richard Samworth. Adaptation in log-concave density estimation (Invited talk) » link » The log-concave maximum likelihood estimator of a density on the real line based on a sample of size $n$ is known to attain the minimax optimal rate of convergence of $O(n^{-4/5})$ with respect to, e.g., squared Hellinger distance. In this talk, we show that it also enjoys attractive adaptation properties, in the sense that it achieves a faster rate of convergence when the logarithm of the true density is $k$-affine (i.e. made up of $k$ affine pieces), provided $k$ is not too large. Our results use two different techniques: the first relies on a new Marshall's inequality for log-concave density estimation, and reveals that when the true density is close to log-linear on its support, the log-concave maximum likelihood estimator can achieve the parametric rate of convergence in total variation distance. Our second approach depends on local bracketing entropy methods, and allows us to prove a sharp oracle inequality, which implies in particular that the rate of convergence with respect to various global loss functions, including Kullback--Leibler divergence, is $O(kn^{-1} \log^{5/4} n)$ when the true density is log-concave and its logarithm is close to $k$-affine. Link » Richard J Samworth Sat 12:00 a.m. - 12:30 a.m. Ming Yuan. Functional nuclear norm and low rank function estimation. (Invited talk) » link » The problem of low rank estimation naturally arises in a number of functional or relational data analysis settings, for example when dealing with spatio-temporal data or link prediction with attributes. We consider a unified framework for these problems and devise a novel penalty function to exploit the low rank structure in such contexts. The resulting empirical risk minimization estimator can be shown to be optimal under fairly general conditions. Link » Ming Yuan Sat 12:30 a.m. - 1:00 a.m. Mladen Kolar. Post-Regularization Inference for Dynamic Nonparanormal Graphical Models. (Invited talk) » link » We propose a novel class of dynamic nonparanormal graphical models, which allows us to model high dimensional heavy-tailed systems and the evolution of their latent network structures. Under this model we develop statistical tests for presence of edges both locally at a fixed index value and globally over a range of values. The tests are developed for a high-dimensional regime, are robust to model selection mistakes and do not require commonly assumed minimum signal strength. The testing procedures are based on a high dimensional, debiasing-free moment estimator, which uses a novel kernel smoothed Kendall's tau correlation matrix as an input statistic. The estimator consistently estimates the latent inverse Pearson correlation matrix uniformly in both index variable and kernel bandwidth. Its rate of convergence is shown to be minimax optimal. Thorough numerical simulations and an application to a neural imaging dataset support the usefulness of our method. Joint work with Junwei Lu and Han Liu. Link » Mladen Kolar Sat 2:00 a.m. - 2:20 a.m. Debarghya Ghoshdastidar, Ulrike von Luxburg. Do Nonparametric Two-sample Tests work for Small Sample Size? A Study on Random Graphs. (Contributed talks) » link » We consider the problem of two-sample hypothesis testing for inhomogeneous unweighted random graphs, where one has access to only a very small number of samples from each model. Standard tests cannot be guaranteed to perform well in this setting due to the small sample size. We present a nonparametric test based on comparison of the adjacency matrices of the graphs, and prove that the test is consistent for increasing sample size as well as when the graph size increases with sample size held fixed. Numerical simulations exhibit the practical significance of the test. Link » Sat 2:20 a.m. - 2:40 a.m. Diana Cai, Trevor Campbell, Tamara Broderick. Paintboxes and probability functions for edge-exchangeable graphs. (Contributed talks) link » Sat 2:40 a.m. - 3:00 a.m. Alessandro Rudi, Raffaello Camoriano, Lorenzo Rosasco. Generalization Properties of Learning with Random Features. (Contributed talks) » link » We study the generalization properties of regularized learning with random features in the statistical learning theory framework. We show that optimal learning errors can be achieved with a number of features smaller than the number of examples. Link » Sat 3:00 a.m. - 3:20 a.m. Makoto Yamada, Yuta Umezu, Kenji Fukumizu, Ichiro Takeuchi. Post Selection Inference with Kernels. (Contributed talks) » link » We propose a novel kernel based post selection inference (PSI) algorithm, which can not only handle non-linearity in data but also structured output such as multi-dimensional and multi-label outputs. Specifically, we develop a PSI algorithm for independence measures, and propose the Hilbert-Schmidt Independence Criterion (HSIC) based PSI algorithm (hsicInf). We apply the hsicInf algorithm to a real-world data, and show that hsicInf can successfully identify important features. Link » Sat 3:20 a.m. - 3:40 a.m. Yunpeng Pan, Xinyan Yan, Evangelos Theodorou, Byron Boots. Solving the Linear Bellman Equation via Kernel Embeddings and Stochastic Gradient Descent. (Contributed talks) » link » We introduce a data-efficient approach for solving the linear Bellman equation, which corresponds to a class of Markov decision processes (MDPs) and stochastic optimal control (SOC) problems. We show that this class of control problem can be reformulated as a stochastic composition optimization problem, which can be further reformulated as a saddle point problem and solved via dual kernel embeddings. Our method is model-free and using only one sample per state transition from stochastic dynamical systems. Different from related work such as Z-learning based on temporal-difference learning, our method is an on-line algorithm exploiting stochastic optimization. Numerical results are provided, showing that our method outperforms the Z-learning algorithm. Link » Sat 3:40 a.m. - 5:30 a.m. Lunch break Sat 5:30 a.m. - 6:00 a.m. Francis Bach. Harder, Better, Faster, Stronger Convergence Rates for Least-Squares Regression. (Invited talk) » link » We consider the optimization of a quadratic objective function whose gradients are only accessible through a stochastic oracle that returns the gradient at any given point plus a zero-mean finite variance random error. We present the first algorithm that achieves jointly the optimal prediction error rates for least-squares regression, both in terms of forgetting of initial conditions in O(1/n^2), and in terms of dependence on the noise and dimension d of the problem, as O(d/n). Our new algorithm is based on averaged accelerated regularized gradient descent, and may also be analyzed through finer assumptions on initial conditions and the Hessian matrix, leading to dimension-free quantities that may still be small while the "optimal " terms above are large. In order to characterize the tightness of these new bounds, we consider an application to non-parametric regression and use the known lower bounds on the statistical performance (without computational limits), which happen to match our bounds obtained from a single pass on the data and thus show optimality of our algorithm in a wide variety of particular trade-offs between bias and variance. [joint work with Aymeric Dieuleveut and Nicolas Flammarion] Link » Francis Bach Sat 6:00 a.m. - 6:30 a.m. Richard (Fangjian) Guo. Boosting Variational Inference. (Invited talk) » link » Modern Bayesian inference typically requires some form of posterior approximation, and mean-field variational inference (MFVI) is an increasingly popular choice due to its speed. But MFVI is inaccurate in several aspects, including an inability to capture multimodality in the posterior and underestimation of the posterior covariance. These issues arise since MFVI considers approximations to the posterior only in a family of factorized parametric distributions. We instead consider a much more flexible approximating family consisting of all possible mixtures of a parametric base distribution (e.g., Gaussians) without constraining the number of mixture components. In order to efficiently find a high-quality posterior approximation within this family, we borrow ideas from gradient boosting and propose the boosting variational inference (BVI) method, which iteratively improves the current approximation by mixing it with a new component from the base distribution family. We develop practical algorithms for BVI and demonstrate their performance on both real and simulated data. Joint work with Xiangyu Wang, Kai Fan, Tamara Broderick and David Dunson. Link » Fangjian Guo Sat 6:30 a.m. - 6:45 a.m. Break Sat 6:45 a.m. - 7:15 a.m. Olga Klopp. Network models and sparse graphon estimation. (Invited talk) » link » Inhomogeneous random graph models encompass many network models such as stochastic block models and latent position models. We consider the problem of statistical estimation of the matrix of connection probabilities based on the observations of the adjacency matrix of the network and derive optimal rates of convergence for this problem. Our results cover the important setting of sparse networks. We also establish upper bounds on the minimax risk for graphon estimation when the probability matrix is sampled according to a graphon model. Link » Olga Klopp Sat 7:15 a.m. - 7:45 a.m. Emily Fox. Sparse Graphs via Exchangeable Random Measures. (Invited talk) » link » Statistical network modeling has focused on representing the graph as a discrete structure, namely the adjacency matrix. Assuming exchangeability of this array, the Aldous-Hoover theorem informs us that the graph is necessarily either dense or empty. We instead consider representing the graph as a point process on the positive quadrant. We then propose a graph construction leveraging completely random measures (CRMs) that leads to an exchangeable point process representation of graphs ranging from dense to sparse and exhibiting power-law degree distributions. We show how these properties are simply tuned by three hyperparameters. The resulting model lends itself to an efficient MCMC scheme from which we can infer these network attributes. We demonstrate our methods on a series of real-world networks with up to hundreds of thousands of nodes and millions of edges. We also discuss some recent advances in this area and open challenges. Joint work with Francois Caron. Link » Emily Fox Sat 7:45 a.m. - 9:00 a.m. Coffee break + posters link »
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http://sci-gems.math.bas.bg/jspui/browse?type=subject&order=ASC&rpp=20&offset=3358
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## Browsing by Subject
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https://digitalcommons.lsu.edu/gradschool_disstheses/5717/
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LSU Historical Dissertations and Theses
1994
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
Erwin D. Poliakoff
Abstract
Highly resolved molecular photoionization is a topic of intense current interest due to insights it provides into fundamental scattering processes. Rotationally resolved data provide a window on the angular momentum composition of the photoelectron and the partitioning of angular momentum between the ion and photoelectron. Since the earliest rotational measurements via photoelectron spectroscopy (PES) of H$\sb2$ using resonance lamp excitation, studies have accelerated as a result of experimental innovations. However, all of these recent developments have been limited to threshold or near-threshold ionization phenomena. In order to bypass this constraint, we have employed dispersed fluorescence measurements. This strategy allows us to exploit the broad tunability of synchrotron radiation because the detection bandwidth is uncoupled from the excitation bandwidth. The isoelectronic target molecules N$\sb2$ and CO are rotationally cooled by a supersonic expansion, and ionized by synchrotron radiation from a 6-m Plane Grating Monochromator (PGM), at the Louisiana State University Center for Advanced Microstructures and Devices (CAMD). The rotational fluorescence spectra are obtained over the energy range from $\rm20\ \le\ h\nu\sb{exc}\ \le\ 220$ eV for $\rm N\sb2\ 2\sigma\sb{u}\sp{-1}$ photoionization and from $\rm23\ \le\ h\nu\sb{exc}\ \le\ 145$ eV for CO 4$\sigma\sp{-1}$ photoionization. The results of $\rm N\sb2\sp+(B\sp2\Sigma\sb{u}\sp+$) and $\rm CO\sp+(B\sp2\Sigma\sp+$) rotational distributions show strikingly different energy dependences. Detailed calculations reveal that the dramatically changing $\rm N\sb2\sp+(B\sp2\Sigma\sb{u}\sp+$) rotational distributions arise from Cooper minima of g- and d-waves in the k$\sigma\sb{\rm g}$ photoelectron continuum, while the flatness of $\rm CO\sp+(B\sp2\Sigma\sp+$) rotational distributions results from a delicate balance between the $4\sigma\ \to\ {\rm k}\sigma\ f$-wave shape resonance and the broad f-wave enhancement in k$\pi$ photoelectron continuum. Cooper minima for $\rm N\sb2\ 2\sigma\sb{u}\sp{-1}$ ionization lead to small $\Delta N$ transitions at lower energies and large $\Delta N$ transitions at higher energies, while the CO $\rm 4\sigma\ \to\ k\sigma$ shape resonance results in larger $\Delta N$ transitions over the whole energy range studied. The present studies of $\rm N\sb2\sp+(B\sp2\Sigma\sb{u}\sp+$) and $\rm CO\sp+(B\sp2\Sigma\sp+$) rotational distributions illustrate effects of Cooper minima, shape resonances, and l mixing in photoelectron continua at energies well beyond the reach of conventional photoelectron spectroscopy. Moreover, these results also demonstrate that rotationally resolved fluorescence is suitable for studies of molecular photoionization dynamics over a broad spectral range.
103
COinS
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http://www.analyzemath.com/calculus_questions/analytical/calculus_questions_3.html
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# Calculus Questions with Answers (3)
Approximate graphically the first derivative of a function f from its graph. Questions are presented along with solutions.
Question 1: Below is shown the graph of function f. a) Assuming that the only extrema of function f are the ones shown in the graph, for what values of x is f '(x) = 0? b) Assuming that the graph of function f rises indefinitely on the right and on the left, for what values of x is f '(x) negative? For what values of x is f '(x) positive? Solution to Question 1: a) The graph of f has two minimums, one at x = -2 and one at x = 4, and one maximum at x = 1. Therefore f '(x) = 0 for x = -2, x = 1 and x = 4. b) Function f is decreasing on the intervals (- ∞ , -2) and (1 , 4). Hence f' (x) will be negative on these same intervals. Function f is increasing on the intervals (-2 , 1) and (4 , + ∞). Hence f' (x) will be positive on these same intervals. Question 2: The graph of function f is shown below. Assuming that function f is odd and has horizontal asymptotes, approximate graphically the graph of the first derivative f ' of f. Solution to Question 2: We first note that f is an increasing function. Hence f'(x) is positive for all values of and its graph is above the x axis. The value of the first derivative f '(a) at a given value of x = a is equal to the slope of the tangent line at the point (a , f(a)) . Hence, a possible approximation of f '(x) would be an approximation of the slope of the tangent line at the graph of f. For the given graph, it seems that the slope of the tangent line to the graph of f will be maximum around the origin (0,0). Let us use three points A, B and C, close to the origin 0 to approximate the slope mo of the tangent line at x = 0. If points A and C have the coordinates A(xA,yA) and C(xC,yC), then mo may be approximated by mo = (yC - yA) / (xC - xA) = (0.5 - (-0.5))/ (0.5 - (-0.5)) = 1 We can also use points C and E to approximate the slope m1 of the tangent line at point D. m1 = (1 - 0.5) / (1.5 - 0.5) = 0.5 Since f has horizontal asymptotes, we would expect f'(x) to be close to zero as x increases indefinitely (+ ∞) or decreases indefinitely (- ∞). Since f has horizontal asymptotes, we would expect the tangent line to the graph of to be horizontal and its slope close to zero as x increases indefinitely (+ ∞) or decreases indefinitely (- ∞). Using all the above information, one possible approximation of f'(x) would be as shown below in blue. Question 3: Approximate the graph of the first derivative f ' of function f when given the graph of f below. Assume that the graph of f is symmetric with respect to the vertical line x = -0.5 and that f has y = 0 as a horizontal asymptote. Solution to Question 3: Using similar ideas to those used in questions 1 and 2 above, note that f'(x) = 0 at x = -2, -0.5 and 1 since these are the locations of the extrema of f unction f. The groups of three (green) points are used to approximate the slope of the tangent line at the middle point of each group. For example using points D, E and F one can approximate the slope mo of the tangent line at point E as follows mo = (0.8 - 0.4) / (-2.4 - (-2.9)) = 0.8 We can use the next group of the three (green) points, to the right of point A, to approximate the slope at the middle point which will be close to -0.8. The above information may easily be used to plot points on the graph of f' as shown below (blue points). The sign of f'(x) is determined by the increase and decrease of f. Hence f'(x) is positive for values of on the intervals of increase of f given by: (- ∞ , -2) and (-0.5 , 1) f'(x) is negative for values of x in the intervals of decrease of f and are defined by: (-2 , -0.5) and (1 , + ∞) Using all the above information, we may approximate f'(x) as follows (blue graph). | 1 | 2 | 3 | 4 | 5 | More references on calculus questions with answers, tutorials and problems .
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https://whatmaster.com/electrostatics/
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PHYSICS
Electrostatics
Basic Theoretical Information
Electric charge and its properties
The electric charge is a physical quantity that characterizes the ability of particles or bodies to enter into electromagnetic interactions. The electric charge is usually designated by the letters q and Q . In the SI system, the electric charge is measured in Pendants (C). A free charge of 1 C is a huge amount of charge that is practically not found in nature. As a rule, you will have to deal with microcolourants (1 μC = 10 –6 C), nanocolons (1 nC = 10 –9 C) and picoculons (1 p = 10 –12 C). Electric charge has the following properties:
1. Electric charge is a kind of matter.
2. The electric charge does not depend on the motion of the particle and on its speed.
3. Charges can be transferred (for example, by direct contact) from one body to another. Unlike body mass, electric charge is not an integral characteristic of a given body. The same body under different conditions can have a different charge.
4. There are two kinds of electric charges, conventionally called positive and negative .
5. All charges interact with each other. In this case, like charges repel each other, opposite charges attract each other. The forces of interaction of charges are central, that is, they lie on the straight line connecting the centers of charges.
6. There is a minimum possible (modulo) electric charge, called an elementary charge . Its meaning is:
e = 1.602177 · 10 –19 Cl ≈ 1.6 · 10 –19 Cl.
The electric charge of any body is always a multiple of the elementary charge:
where: N is an integer. Please note that the existence of a charge equal to 0.5 e ; 1.7 e ; 22.7 e and so on. Physical quantities that can take only a discrete (non-continuous) series of values are called quantized . Elementary charge e is a quantum (the smallest portion) of electric charge.
7. The law of conservation of electric charge. In an isolated system, the algebraic sum of the charges of all bodies remains constant:
The law of conservation of electric charge states that in a closed system of bodies the processes of creation or disappearance of charges of only one sign cannot be observed. It also follows from the charge conservation law, if two bodies of the same size and shape, having charges 1 and 2 (no matter what sign of charge), come into contact, and then dissolve back, then the charge of each of the bodies becomes equal:
From the modern point of view, charge carriers are elementary particles. All ordinary bodies are composed of atoms, which include positively charged protons , negatively charged electrons and neutral particles – neutrons . Protons and neutrons are part of atomic nuclei, electrons form the electron shell of atoms. The electric charges of the proton and the electron are exactly the same in modulus and equal to the elementary (that is, the minimum possible) charge e .
In a neutral atom, the number of protons in the nucleus is equal to the number of electrons in the shell. This number is called the atomic number. An atom of a given substance may lose one or more electrons, or acquire an extra electron. In these cases, the neutral atom becomes a positively or negatively charged ion. Please note that positive protons are part of the nucleus of an atom, so their number can only change during nuclear reactions. Obviously, when electrifying bodies of nuclear reactions does not occur. Therefore, in any electrical phenomena the number of protons does not change, only the number of electrons changes. So, sending a negative charge to the body means passing extra electrons to it. And the message of a positive charge, in spite of a common error, means not the addition of protons, but the taking of electrons.
Sometimes in problems the electric charge is distributed over a certain body. To describe this distribution, the following values are entered:
1. Linear charge density. Used to describe the charge distribution over a thread:
where: L is the length of the thread. Measured in C / m.
2. Surface charge density. Used to describe the charge distribution over the body surface:
where: S is the surface area of the body. Measured in C / m 2 .
3. Bulk charge density. Used to describe the distribution of charge over body volume:
where: V – body volume. Measured in C / m 3 .
Note that the electron mass is equal to:
e = 9.11 ∙ 10–31 kg.
Coulomb’s law
A point charge is a charged body whose dimensions under the conditions of this task can be neglected. Based on numerous experiments, Coulomb established the following law:
The interaction forces of fixed point charges are directly proportional to the product of charge modules and inversely proportional to the square of the distance between them:
where: ε is the dielectric constant of a medium — a dimensionless physical quantity that indicates how many times the force of electrostatic interaction in a given medium will be less than in a vacuum (that is, how many times the medium weakens the interaction). Here k is the coefficient in the Coulomb law, the value that determines the numerical value of the interaction force of the charges. In the SI system, its value is assumed to be:
k = 9 ∙ 10 9 m / F.
The interaction forces of the pointless stationary charges obey the third law of Newton, and are repulsive forces from each other with the same signs of charges and forces of attraction to each other with different signs. The interaction of fixed electric charges is called electrostatic or Coulomb interaction. The section of electrodynamics that studies the Coulomb interaction is called electrostatics .
Coulomb’s law is valid for point charged bodies, uniformly charged spheres and balls. In this case, for distances r take the distance between the centers of spheres or balls. In practice, the Coulomb’s law is well satisfied if the size of charged bodies is much smaller than the distance between them. The coefficient k in the SI system is sometimes written in the form:
where: ε 0 = 8.85 ∙ 10 –12 F / m is the electric constant.
Experience shows that the forces of the Coulomb interaction obey the superposition principle: if a charged body interacts simultaneously with several charged bodies, then the resultant force acting on a given body is equal to the vector sum of the forces acting on this body from all other charged bodies.
Remember also two important definitions:
Conductors – substances containing free charge carriers. Inside the conductor, free movement of electrons – charge carriers is possible (an electric current can flow through the conductors). The conductors include metals, solutions and melts of electrolytes, ionized gases, plasma.
Dielectrics (insulators) are substances in which there are no free charge carriers. The free movement of electrons inside dielectrics is impossible (no electric current can flow through them). It is dielectrics that have some non-unit dielectric constant ε .
For the dielectric constant of a substance, the following is true (that is, an electric field is slightly lower):
Electric field and its intensity
According to modern concepts, electric charges do not act on each other directly. Each charged body creates an electric field in the surrounding space . This field has a powerful effect on other charged bodies. The main property of the electric field is the effect on electric charges with some force. Thus, the interaction of charged bodies is carried out not by their direct action against each other, but through the electric fields surrounding the charged bodies.
The electric field surrounding a charged body can be investigated with the help of the so-called trial charge — a small point charge that does not introduce a noticeable redistribution of the charges under study. To quantify the electric field force characteristic is introduced – the electric field strength E .
The strength of the electric field is called a physical quantity equal to the ratio of the force with which the field acts on the trial charge placed at a given point of the field to the magnitude of this charge:
Electric field strength is a vector physical quantity. The direction of the intensity vector coincides at each point in space with the direction of the force acting on the positive test charge. The electric field of the fixed and unchanging with time charges is called electrostatic.
For a visual representation of the electric field using lines of force . These lines are drawn so that the direction of the intensity vector at each point coincides with the direction of the tangent to the field line. Power lines have the following properties.
• The power lines of the electrostatic field never intersect.
• The electrostatic field lines are always directed from positive to negative charges.
• When depicting an electric field with the help of lines of force, their density should be proportional to the modulus of the field intensity vector.
• Power lines start at a positive charge or infinity, and end at a negative or infinity. The density of the lines is greater, the greater the tension.
• At this point in space, only one line of force can pass; The electric field strength at a given point in space is uniquely defined.
An electric field is called homogeneous if the intensity vector is the same at all points of the field. For example, a uniform field creates a flat capacitor — two plates, charged by an equal in magnitude and opposite in sign charge, separated by a dielectric layer, and the distance between the plates is much smaller than the sizes of the plates.
At all points of a uniform field, a charge q introduced into a uniform field with a strength E acts on the same in magnitude and direction force, equal to F = Eq . Moreover, if the charge q is positive, then the direction of the force coincides with the direction of the intensity vector, and if the charge is negative, then the strength and intensity vectors are oppositely directed.
The force lines of the Coulomb fields of positive and negative point charges are shown in the figure:
Principle of superposition
If using a trial charge, the electric field created by several charged bodies is investigated, then the resulting force is equal to the geometric sum of the forces acting on the trial charge from each charged body separately. Consequently, the intensity of the electric field created by the charge system at a given point in space is equal to the vector sum of the strengths of the electric fields created at the same point by the charges separately:
This property of the electric field means that the field obeys the superposition principle . In accordance with the Coulomb’s law, the strength of the electrostatic field created by a point charge Q at a distance r from it is equal in absolute value:
This field is called Coulomb. In the Coulomb field, the direction of the intensity vector depends on the sign of the charge Q: if Q > 0, then the intensity vector is directed from the charge, if Q <0, then the intensity vector is directed towards the charge. The magnitude of the strength depends on the magnitude of the charge, the medium in which the charge is located, and decreases with increasing distance.
The electric field strength, which creates a charged plane near its surface:
So, if in the task it is required to determine the field strength of the charge system, then we must act according to the following algorithm :
1. Draw a picture.
2. Draw the field strength of each charge separately at the desired point. Remember that the intensity is directed towards the negative charge and from the positive charge.
3. Calculate each of the tensions using the appropriate formula.
4. Add the stress vector geometrically (i.e., vector).
Potential charge interaction energy
Electric charges interact with each other and with the electric field. Any interaction describes the potential energy. The potential energy of interaction of two point electric charges is calculated by the formula:
Pay attention to the absence of modules in charges. For opposite charges, the interaction energy is negative. The same formula is valid for the interaction energy of uniformly charged spheres and balls. As usual, in this case the distance r is measured between the centers of the balls or spheres. If the charges are not two, but more, then the energy of their interaction should be considered as follows: break the system of charges into all possible pairs, calculate the interaction energy of each pair and sum up all the energies for all pairs.
Tasks on this topic are solved, as well as tasks on the law of conservation of mechanical energy: first, the initial interaction energy is found, then the final one. If the task is asked to find work on the movement of charges, then it will be equal to the difference between the initial and final total interaction energy of the charges. The interaction energy can also transfer to kinetic energy or to other forms of energy. If the bodies are at a very large distance, then the energy of their interaction is set to 0.
Note: if the task requires to find the minimum or maximum distance between the bodies (particles) while moving, then this condition will be fulfilled at that moment of time when the particles move in one direction with the same speed. Therefore, the solution must begin with the recording of the law of conservation of momentum, from which this identical velocity is found. And then you should write the law of energy conservation taking into account the kinetic energy of the particles in the second case.
Potential. Potential difference. Voltage
The electrostatic field has an important property: the work of the electrostatic field forces when a charge moves from one point of the field to another does not depend on the shape of the trajectory, but is determined only by the position of the initial and final points and the charge value.
The consequence of the independence of the work from the shape of the trajectory is the following statement: the work of the electrostatic field forces when the charge moves along any closed trajectory is zero.
The property of potentiality (independence of work from the shape of the trajectory) of an electrostatic field allows one to introduce the concept of potential energy of a charge in an electric field. A physical quantity equal to the ratio of the potential energy of an electric charge in an electrostatic field to the magnitude of this charge is called the potential φ of the electric field:
The potential φ is the energy characteristic of the electrostatic field. In the International System of Units (SI), the potential unit (and hence the potential difference, i.e. voltage) is the volt [V]. Potential is a scalar quantity.
In many problems of electrostatics when calculating the potentials for the reference point, where the values of potential energy and potential turn to zero, it is convenient to take an infinitely distant point. In this case, the concept of potential can be defined as follows: the potential of the field at a given point in space is equal to the work that the electric forces do when a single positive charge is removed from a given point to infinity.
Recalling the formula for the potential energy of the interaction of two point charges and dividing it by the value of one of the charges in accordance with the definition of potential, we obtain that the potential φ of the point charge field Q at a distance r from it relative to an infinitely remote point is calculated as follows
The potential calculated by this formula can be positive and negative, depending on the sign of the charge that created it. The same formula expresses the potential of the field of a uniformly charged ball (or sphere) with r ≥ R (outside the ball or sphere), where R is the radius of the ball, and the distance r is measured from the center of the ball.
For a visual representation of the electric field, along with the lines of force, equipotential surfaces are used . A surface, at all points of which the potential of the electric field has the same value, is called an equipotential surface or a surface of equal potential. The electric field lines are always perpendicular to the equipotential surfaces. The equipotential surfaces of the Coulomb field of a point charge are concentric spheres.
Electrical voltage is simply a voltage difference, i.e. The definition of electrical voltage can be given by:
In a uniform electric field, there is a relationship between field strength and voltage:
The work of the electric field can be calculated as the difference between the initial and final potential energy of the charge system:
The work of the electric field in the general case can also be calculated by one of the formulas:
In a uniform field when the charge moves along its lines of force, the field operation can also be calculated using the following formula:
In these formulas:
• φ is the electric field potential.
• ∆ φ is the potential difference.
• W is the potential energy of a charge in an external electric field.
• A – the work of the electric field on the movement of charge (charges).
• q – charge, which is moved in an external electric field.
• U is the voltage.
• E is the electric field strength.
• d or ∆ l is the distance over which the charge moves along the lines of force.
All the previous formulas dealt specifically with the work of the electrostatic field, but if the task states that “the work must be done,” or it is referred to the “work of external forces,” then this work should be considered the same as the work of the field, but with opposite sign.
Principle of superposition of potential
The principle of superposition for potentials follows from the principle of superposition of the strengths of fields generated by electric charges (the sign of the field potential depends on the sign of the charge that created the field):
Notice how much easier it is to apply the principle of superposition of potential than tension. Potential is a scalar quantity that has no direction. Adding potentials is simply summing up the numerical values.
Electric capacity Flat capacitor
When communicating to the charge conductor, there is always a certain limit, over which the body cannot be charged. To characterize the body’s ability to accumulate electrical charge, the concept of electrical capacitance is introduced . The capacity of a solitary conductor is the ratio of its charge to potential:
In the SI system, capacitance is measured in Farads [F]. 1 Farad – extremely large capacity. For comparison, the capacity of the entire globe is significantly less than one farad. The capacity of the conductor does not depend on its charge, nor on the potential of the body. Similarly, density does not depend on mass or on the volume of the body. Capacity depends only on the shape of the body, its size and the properties of its environment.
The electrical capacity of a system of two conductors is a physical quantity, defined as the ratio of the charge q of one of the conductors to the potential difference Δ φ between them:
The amount of electrical capacity of conductors depends on the shape and size of the conductors and on the properties of the dielectric separating the conductors. There are configurations of conductors in which the electric field is concentrated (localized) only in a certain region of space. Such systems are called capacitors , and the conductors that make up the capacitor are called plates .
The simplest capacitor is a system of two flat conducting plates arranged parallel to each other at a small distance compared to the dimensions of the plates and separated by a dielectric layer. Such a capacitor is called flat . The electric field of a plane capacitor is mainly localized between the plates.
Each of the charged plates of a flat capacitor creates an electric field near its surface, the strength of which is expressed by the ratio already mentioned above. Then the modulus of the strength of the final field inside a capacitor created by two plates is equal to:
Outside of the capacitor, the electric fields of the two plates are directed in different directions, and therefore the resulting electrostatic field is E = 0. The capacitance of the flat capacitor can be calculated by the formula
Thus, the electrical capacitance of a flat capacitor is directly proportional to the area of the plates (plates) and inversely proportional to the distance between them. If the space between the plates is filled with a dielectric, the capacitance of the capacitor increases by a factor of ε . Note that S in this formula is the area of only one capacitor plate. When the problem is referred to as “area of the plates”, they mean precisely this quantity. It is never necessary to multiply or divide by 2.
Once again we give the formula for charging the capacitor . Under the charge of the capacitor understand only the charge of its positive lining:
The force of attraction of the capacitor plates. The force acting on each plate is determined not by the full field of the capacitor, but by the field created by the opposite plate (the plate itself does not act). The strength of this field is equal to half the strength of the total field, and the strength of the interaction of the plates:
Condenser energy. It is also called the energy of the electric field inside the capacitor. Experience shows that a charged capacitor contains a supply of energy. The energy of a charged capacitor is equal to the work of external forces, which must be expended to charge the capacitor. There are three equivalent forms for writing a formula for the energy of a capacitor (they follow one of the other if we use the relation q = CU ):
Pay special attention to the phrase: “The capacitor is connected to the source.” This means that the voltage across the capacitor does not change. And the phrase “The capacitor was charged and disconnected from the source” means that the charge of the capacitor will not change.
Electric field energy
Electrical energy should be considered as potential energy stored in a charged capacitor. According to modern concepts, the electric energy of a capacitor is localized in the space between the capacitor plates, that is, in an electric field. Therefore, it is called the electric field energy. The energy of charged bodies is concentrated in space, in which there is an electric field, i.e. You can talk about the energy of the electric field. For example, for a capacitor, energy is concentrated in the space between its plates. Thus, it makes sense to introduce a new physical characteristic – the bulk density of the electric field energy. Using the example of a flat capacitor, one can obtain the following formula for the bulk energy density (or energy per unit volume of the electric field):
Capacitor connections
A Parallel connection of capacitors – to increase capacity. Capacitors are connected by the same charged plates, as if increasing the area of equally charged plates. The voltage on all capacitors is the same, the total charge is equal to the sum of the charges of each of the capacitors, and the total capacity is also equal to the sum of the capacitors of all the capacitors connected in parallel. We write the formulas for parallel connection of capacitors:
When connecting capacitors in series, the total capacitance of the capacitor bank is always less than the capacity of the smallest capacitor entering the battery. A series connection is used to increase the breakdown voltage of capacitors. We write the formulas for the serial connection of capacitors. The total capacitance of series-connected capacitors is found from the relationship:
From the law of conservation of charge, it follows that the charges on the adjacent plates are equal:
The voltage is equal to the sum of the voltages on the individual capacitors.
For two series-connected capacitors, the formula above will give us the following expression for the total capacity:
For N identical series-connected capacitors:
Conductive sphere
The field strength inside the charged conductor is zero. Otherwise, the free charges inside the conductor would be acted upon by an electric force, which would force these charges to move inside the conductor. This movement, in turn, would lead to heating of the charged conductor, which in fact does not occur.
The fact that there is no electric field inside the conductor can be understood in another way: if it were, then the charged particles would move again, and they would move precisely so as to reduce this field to zero by its own field, since in general, they would not want to move, because any system tends to equilibrium. Sooner or later, all moving charges would stop at exactly that place so that the field inside the conductor becomes equal to zero.
On the surface of the conductor the electric field strength is maximum. The magnitude of the electric field of a charged ball outside it decreases with distance from the conductor and is calculated using a formula similar to the formulas for the field strength of a point charge, in which the distances are measured from the center of the ball.
Since the field strength inside a charged conductor is zero, the potential at all points inside and on the surface of the conductor is the same (only in this case, the potential difference, and hence the strength is zero). The potential inside a charged ball is equal to the potential on the surface. The potential outside the ball is calculated by a formula similar to the formulas for the point charge potential, in which the distances are measured from the center of the ball.
Electrical capacity of the ball of radius R :
If the ball is surrounded by a dielectric, then:
Properties of the conductor in the electric field
1. Inside the conductor, the field strength is always zero.
2. The potential inside the conductor at all points is the same and equal to the potential of the surface of the conductor. When the problem says that “the conductor is charged to the potential … B”, then it is the surface potential that is meant.
3. Outside of the conductor near its surface, the field strength is always perpendicular to the surface.
4. If the conductor is charged, it is distributed over a very thin layer near the surface of the conductor (they usually say that the entire charge of the conductor is distributed on its surface). This is easily explained: the fact is that when we communicate the charge to the body, we give it charge carriers of the same sign, i.e. charges of the same name that repel each other. So they will strive to scatter from each other to the maximum distance of all possible, i.e. accumulate at the very edges of the conductor. As a result, if the core is removed from the conductor, its electrostatic properties will not change at all.
5. Outside the conductor, the field strength is greater, the more curved the surface of the conductor. The maximum value of tension is reached near the tips and sharp kinks of the conductor surface.
Tips for solving complex problems
1. Grounding something means connecting the conductor of a given object to the Earth. In this case, the potentials of the Earth and the existing object are aligned, and the necessary charges for this run across the conductor from the Earth to the object or vice versa. In this case, it is necessary to take into account several factors that follow from the fact that the Earth is disproportionately larger than any object that is not located there:
• The total charge of the Earth is conventionally equal to zero, therefore its potential is also equal to zero, and it will remain equal to zero after the connection of the object with the Earth. In short, grounding means zeroing the potential of the object.
• To reset the potential (and hence the object’s own charge, which could have been both positive and negative), the object will have to either accept or give the Earth some (possibly very large) charge, and the Earth will always be able to provide such an opportunity.
2. We repeat once again: the distance between repulsive bodies is minimal at the moment when their velocities become equal in magnitude and are directed in one direction (the relative velocity of the charges is zero). At this moment, the potential energy of the interaction of charges is maximum. The distance between the attracting bodies is maximal, also at the moment of equality of speeds directed in one direction.
3. If the problem has a system consisting of a large number of charges, then it is necessary to consider and describe the forces acting on a charge that is not in the center of symmetry.
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https://nxttime.wordpress.com/2013/01/14/agilis-my-new-robot/
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This Christmas holiday I started working on a new robot, called Agilis. This robot should be a very agile and elegantly moving robot. The frame is based on a triangle equipped with holonomic wheels. So you might think, “What’s new, it is like your last robot?”. From the outside this is true, but it gets new and better brains on the inside. Let me tell you what I envision.
Most robots I built went from point A to point B, only then to decide what to do next. Others just drove around avoiding obstacles. This one should be able to do both at the same time. Agilis must be able to perform complex manouvres, like driving in a straight line while rotating around its centre, or like driving an arc while keeping pointed at an arbitrary spot. It should constantly use sensory input to stay on course, or to alter its course if needed. And all this must go fluently, just like a cat walking through the room.
Over the next several posts I will discuss the different aspects of Agilis. This first post deals with the drive system.
## the chassis
Agilis is a three wheeled holonomic platform. This means it can drive in any direction without turning. It can turn around any point, even around its own center. Each wheel is driven by a NXT motor via a gear train that has a 1:2 ratio, the wheels rotate twice as fast as the motors. This makes Agilis a relatively fast robot. The gear train has to be very sturdy to handle the torque of the motors. It also has to be precise to allow for odometry. I used the same setup that I developed for my last robot, Koios the Guard bot.
## From robot speed to motor speed
It is not very easy to control a holonomic robot, it takes some math. I created a kinematic model that does just that. The model takes robot speed as input and gives motor speed as output. Robot speed is expressed as speed in x-direction, y-direction and rotational speed. Motor speed is expressed as encoder ticks per second.
So how does this kinematic model look like? For a single wheel this looks like a function that takes the three robot speeds as input. For the three wheels together it looks like a matrix multiplication that multiplies a robot speed vector {xSpeed,ySpeed,angularSpeed} with a kinematic matrix. The resulting vector containers the speed of each of the three wheels. Let’s take a look at the single wheel function first.
To translate robot speed into motor speed one needs to know some physical aspects of the robot, the wheel and the motor. How big is the wheel, how far is it from the center of the robot, under what angle is it mounted, what is the gear ratio of the gear train and what is the number of encoder ticks per full cycle of the motor? With all this information one can write a formula to calculate motor speed from robot speed. Here is the formula.
motorSpeed =
xSpeed * (cosine(wheelAngle) * nEncoderTicks / ( gearRatio * 2 * PI * wheelRadius) -
ySpeed * (sinus(wheelAngle) * nEncoderTicks / (gearRatio * 2 * PI * wheelRadius) +
angularSpeed * distanceToCenter * nEncoderTicks / (gearRatio * 2 * PI * wheelRadius)
This formula might look daunting at first, but on second glance you might notice that there are a lot of constants in it. If you substitute the constants with their respective values you will end up with a much simpler formula.
motorSpeed = xSpeed * aConstantValue - ySpeed * anotherConstantValue + angularSpeed * yetAnotherConstantValue
This formula is not only much simpler, it is also very efficient to calculate, just three multiplications and two additions. A NXT can do this in no time. But remember, these constants are not the same for all the motors because each of the wheels has a different wheelAngle. But, you could also have wheels of different sizes, or differences in any of the other aspects. This means that you will have a formula for each of the motors, each formula is the same in structure but has its own constants. These constants can be stored in a matrix where each row in the matrix contains the 3 constants belonging to a single wheel. The matrix has a row for each of the wheels. If you then take the speed vector and multiply this with the matrix then all formulas are calculated at once and the result, the motorSpeed, is stored in a new vector. Each row in this vector holds the speed of a single motor. In java this matrix multiplication would look like this:
Matrix motorSpeed = kinematicModel.times(robotSpeed);
Wow, now things look simple at last! This is the beauty of matrix algebra.
The same kinematic model can be used to transform robot acceleration into motor acceleration. I use this to make my robot accelerate very smoothly. (the regulated motor class of Lejos supports regulated acceleration).
## From tacho counter to robot position
To drive a robot this kinematic model works perfect. But I also want to be able to do things the other way around. I want to be able to calculate robot position from encoder values. At first I couldn’t figure this out at all. The math was just too complex for my mind. That is, until I realized that I just needed to use the inverse of the kinematic model.
deltaRobotPose = deltaMotorPosition * inverseKinematicModel
Here deltaMotorPosition is a vector containing the change in encoder value of each of the motors since the previous measurement. The inverseKinematicModel is the kinematic model inverted. And deltaRobotPose is the change in pose (x and y position and heading) of the robot. Looks simple, doesn’t it? The problem is how to calculate the inverse matrix of the kinematic model. I can’t tell you, because I don’t know. But hey, somebody else already programmed this in Java. I just used the inverse method of the Matrix class.
## From the robots coordinates to the worlds coordinates
There is just one more thing to it. The robot can have any heading, this means that x and y coordinates of the robot are not aligned with the x and y coordinates of the world. To be able to steer the robot to a certain position in a room one must be able to convert this location to a location as the robot sees it. The same goes for keeping track of pose. We have seen the formula to calculate change in pose from the wheel encoders. This change however is a change as the robot sees it, not a change in the robots position it the world. The translation from world coordinates to robot coordinates can also be done with a simple matrix multiplication using a rotation matrix. The rotation matrix itself can be calculated from the heading of the robot.
Suppose you want to drive your robot to the left side of the room. The speed matrix in world frame would look like {0, speed, 0}. this can be multiplied with the rotation matrix to get a speed matrix as the robot sees it.
RobotSpeed =worldSpeed * rotationMatrix
If we want to go the other way around, to get the change in pose in world frame we multiply the change in robot frame with the (you guessed it) inverse of the rotation matrix. For rotation matrices the inverse is the same as the transpose of the matrix, the transpose is far more efficient to calculate.
## Wrap up
This really is all there is to driving a robot. To sum it up. You have a kinematic model to translate robot speed into motor speed. You have a rotation matrix to translate things from world coordinates to robot coordinates.
The same goes for odometry. You have the inverse of the kinematic model to translate change in encoder values to change in robot pose expressed in robot coordinates. You have the inverse of the rotation matrix to translate change robot pose in robot coordinates into world coordinates.
The kinematic model is a constant, it has to be calculated only once (unless your robot changes shape). The rotation matrix on the other hand has to be updated every time the heading of he robot changes.
## The implementation
the robot uses lejos as its brains. Lejos has some excellent classes to drive the NXT motors. The regulated motor class that I used is able to rotate a motor at any given speed. This speed is maintained no matter what the conditions are. It also supports setting an acceleration rate. This is very good for my robot, as for most movements the wheel speed of the three motors is different. If all wheels would accelerate equally, then the slower moving motors would reach their target speed sooner than the faster spinning motors. This results in a robot that shivers and shakes during acceleration (or breaking). All this can be avoided by setting an acceleration value for each of the motors. The ratio of the acceleration values must be the same as the ratio between the (difference between current speed and) target speed of each of the motors. If done properly the robot accelerates very smoothly without jerky movements.
Lejos also has a Matrix class that helps to perform matrix algebra. I used this class to store the (inverse) kinematic models and the rotation matrix. I subclassed it to make a Pose Class that can be used together with the matrix class.
To create the kinematic model I developed a Builder class. This class has all kinds of methods to describe the robot, the wheels the motors and the gear train. When you are done describing the robot, the builder class delivers you a kinematic model and an inverse kinematic model.
To drive the robot I made a kind of pilot class. I plan to discuss it in a future post. This pilot accepts the kinematic model in its constructor.
For odometry I made another class, the Odometer. This class uses the inverse kinematic model.
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http://blog.invibe.net/posts/2016-11-17-finding-extremal-values-in-a-nd-array.html
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# 2016-11-17 Finding extremal values in a nd-array
Sometimes, you need to pick up the $N$-th extremal values in a mutli-dimensional matrix.
Let's suppose it is represented as a nd-array (here, I further suppose you are using the numpy library from the python language). Finding extremal values is easy with argsort but this function operated on 1d vectors... Juggling around indices is sometimes not such an easy task, but luckily, we have the unravel_index function.
Let's unwrap an easy solution combining these functions:
Let's first initialize the notebook:
In [1]:
import numpy as np
Let's first a dummy 3-D array:
In [2]:
x = np.array([[0, 5, 4], [2, 1, 3]])
x = np.arange(2*3*4).reshape((4, 3, 2))
x = np.random.permutation(np.arange(2*3*4)).reshape((4, 3, 2))
print (x)
[[[20 6]
[23 18]
[ 0 5]]
[[10 3]
[13 1]
[11 8]]
[[21 7]
[22 14]
[19 12]]
[[17 9]
[ 2 15]
[16 4]]]
Which we can represent as a 1-d array (a vector):
In [3]:
print (x.ravel())
[20 6 23 18 0 5 10 3 13 1 11 8 21 7 22 14 19 12 17 9 2 15 16 4]
We may now find the list of indices to sort it:
In [4]:
print (np.argsort(x.ravel()))
[ 4 9 20 7 23 5 1 13 11 19 6 10 17 8 15 21 22 18 3 16 0 12 14 2]
And we verify that the entries are indeed sorted:
In [5]:
print (x.ravel()[np.argsort(x.ravel())])
[ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23]
To go back to the nd-array, we use the unraval_index function:
In [6]:
help(np.unravel_index)
Help on built-in function unravel_index in module numpy.core.multiarray:
unravel_index(...)
unravel_index(indices, dims, order='C')
Converts a flat index or array of flat indices into a tuple
of coordinate arrays.
Parameters
----------
indices : array_like
An integer array whose elements are indices into the flattened
version of an array of dimensions dims. Before version 1.6.0,
this function accepted just one index value.
dims : tuple of ints
The shape of the array to use for unraveling indices.
order : {'C', 'F'}, optional
Determines whether the indices should be viewed as indexing in
row-major (C-style) or column-major (Fortran-style) order.
Returns
-------
unraveled_coords : tuple of ndarray
Each array in the tuple has the same shape as the indices
array.
--------
ravel_multi_index
Examples
--------
>>> np.unravel_index([22, 41, 37], (7,6))
(array([3, 6, 6]), array([4, 5, 1]))
>>> np.unravel_index([31, 41, 13], (7,6), order='F')
(array([3, 6, 6]), array([4, 5, 1]))
>>> np.unravel_index(1621, (6,7,8,9))
(3, 1, 4, 1)
In [7]:
print (np.unravel_index(np.argsort(x.ravel()), x.shape))
(array([0, 1, 3, 1, 3, 0, 0, 2, 1, 3, 1, 1, 2, 1, 2, 3, 3, 3, 0, 2, 0, 2, 2,
0]), array([2, 1, 1, 0, 2, 2, 0, 0, 2, 0, 0, 2, 2, 1, 1, 1, 2, 0, 1, 2, 0, 0, 1,
1]), array([0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0,
0]))
Such that we can now sort the whole array from the lowest to highest index:
In [8]:
print (x[np.unravel_index(np.argsort(x.ravel()), x.shape)])
[ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23]
We can now pick just the datapoints extremal values of interest :
In [9]:
datapoints = 10
print (np.unravel_index(np.argsort(x.ravel())[:datapoints], x.shape))
(array([0, 1, 3, 1, 3, 0, 0, 2, 1, 3]), array([2, 1, 1, 0, 2, 2, 0, 0, 2, 0]), array([0, 1, 0, 1, 1, 1, 1, 1, 1, 1]))
Let's now try with a more generic example :
In [10]:
x = np.random.rand(4, 3, 2)
print (x)
[[[ 0.43933303 0.35481207]
[ 0.04459993 0.65894333]
[ 0.68128816 0.6476884 ]]
[[ 0.45980888 0.79537777]
[ 0.85516965 0.95558241]
[ 0.26402052 0.25199538]]
[[ 0.75092699 0.88245315]
[ 0.39587322 0.69577732]
[ 0.97255091 0.26780385]]
[[ 0.45577996 0.49798838]
[ 0.36976289 0.32772751]
[ 0.28368218 0.85828921]]]
The indices for the datapoints extremal values of interest are :
In [11]:
print (np.unravel_index(np.argsort(x.ravel())[:datapoints], x.shape))
(array([0, 1, 1, 2, 3, 3, 0, 3, 2, 0]), array([1, 2, 2, 2, 2, 1, 0, 1, 1, 0]), array([0, 1, 0, 1, 0, 1, 1, 0, 0, 0]))
... which correspond to the minimal values of interest :
In [12]:
print (x[np.unravel_index(np.argsort(x.ravel())[:datapoints], x.shape)])
[ 0.04459993 0.25199538 0.26402052 0.26780385 0.28368218 0.32772751
0.35481207 0.36976289 0.39587322 0.43933303]
Note that it is also easy to pick the maximal values :
In [13]:
print (np.unravel_index(np.argsort(-x.ravel())[:datapoints], x.shape))
(array([2, 1, 2, 3, 1, 1, 2, 2, 0, 0]), array([2, 1, 0, 2, 1, 0, 0, 1, 2, 1]), array([0, 1, 1, 1, 0, 1, 0, 1, 0, 1]))
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https://socratic.org/questions/how-do-you-rationalize-sqrt-5-8
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Algebra
Topics
# How do you rationalize sqrt(5/8)?
Write it as: $\frac{\sqrt{5}}{\sqrt{8}}$
then multiply and divide by $\sqrt{8}$ to get:
$\frac{\sqrt{5}}{\sqrt{8}} \cdot \frac{\sqrt{8}}{\sqrt{8}} = \frac{\sqrt{5} \sqrt{8}}{8} =$
$= \frac{\sqrt{5} \sqrt{4 \cdot 2}}{8} = 2 \frac{\sqrt{5} \sqrt{2}}{8} = \frac{\sqrt{5} \sqrt{2}}{4} = \frac{\sqrt{10}}{4}$
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https://gamedev.stackexchange.com/questions/95258/rpg-accuracy-formula-hit-or-miss-only
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# RPG - Accuracy Formula (HIT or MISS only)
I am creating the combat system of a simple RPG. The only two factors in this system are damage and accuracy.
Accuracy in this game simply means either the attacker HITS or MISSES. There is no partial damage or partial hits. The target has no chance of dodging the attack if the attacker HITS. A player's accuracy is represented with a percentage, e.g. 75% of the time the player will HIT.
In combat, the damage formula determines the damage inflicted on a target, but the damage will only be inflicted if the player HITS the target.
I have already created a damage formula; however, I do not know how to create a simple and practical accuracy formula. I have thought of this, but it's quite impractical because of how it will need to be manipulated if the player's accuracy improves/increases:
• An array is filled (Player's accuracy)% with 1's, remaining percent with 0's
• At random, one index of the array is chosen
• If it's a 1, the player HITS; if it's a 0, the player MISSES
I have looked around this network at accuracy/hit or miss formulas but they involve other factors such as dexterity and evasion. I've also looked elsewhere online, but again the formulas involve other factors.
Is there a simple and practical formula to accomplish this?
A random number generator and a simple test is all you need, for example, in C#:
Random rnd = new Random();
int value = rnd.Next(100);
if(value < accuracyValue) {
//We have a hit
} else {
//We have a miss
}
This works when accuracyValue is a number between 0 and 100, representing the player's hit chance. For example, a hit chance of 75% would be accuracyValue = 75;.
We choose a random value between 0 and 100. For any number between 0 and 100, 75 of those numbers will be below 75 (because 0 is included). That means, choosing a random number between 0 and 100 gives us a 75% chance of getting a number below 75. This results in a simple way to get true or false at a specific percentage.
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https://sciencehouse.wordpress.com/author/ccc1685/
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# Phase transitions may explain why SARS-CoV-2 spreads so fast and why new variants are spreading faster
J.C.Phillips, Marcelo A.Moret, Gilney F.Zebende, Carson C.Chow
## Abstract
The novel coronavirus SARS CoV-2 responsible for the COVID-19 pandemic and SARS CoV-1 responsible for the SARS epidemic of 2002-2003 share an ancestor yet evolved to have much different transmissibility and global impact 1. A previously developed thermodynamic model of protein conformations hypothesized that SARS CoV-2 is very close to a new thermodynamic critical point, which makes it highly infectious but also easily displaced by a spike-based vaccine because there is a tradeoff between transmissibility and robustness 2. The model identified a small cluster of four key mutations of SARS CoV-2 that predicts much stronger viral attachment and viral spreading compared to SARS CoV-1. Here we apply the model to the SARS-CoV-2 variants Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1) and Delta (B.1.617.2)3 and predict, using no free parameters, how the new mutations will not diminish the effectiveness of current spike based vaccines and may even further enhance infectiousness by augmenting the binding ability of the virus.
https://www.sciencedirect.com/science/article/pii/S0378437122002576?dgcid=author
This paper is based on the ideas of physicist Jim Phillips, (formerly of Bell Labs, a National Academy member, and a developer of the theory behind Gorilla Glass used in iPhones). It was only due to Jim’s dogged persistence and zeal that I’m even on this paper although the persistence and zeal that ensnared me is the very thing that alienates most everyone else he tries to recruit to his cause.
Jim’s goal is to understand and characterize how a protein will fold and behave dynamically by utilizing an amino acid hydrophobicity (hydropathy) scale developed by Moret and Zebende. People have been developing hydropathy scores for many decades as a way to understand proteins with the idea that hydrophobic amino acids (residues) will tend to be on the inside of proteins while hydrophillic residues will be on the outside where the water is. There are several existing scores but Moret and Zebende, who are physicists and not chemists, took a different tack and found how the solvent-accessible surface area (ASA) scales with the size of a protein fragment with a specific residue in the center. The idea being that the smaller the ASA the more hydrophobic the residue. As protein fragments get larger they will tend to fold back on themselves and thus reduce the ASA. They looked at several thousand protein fragments and computed the average ASA with a given amino acid in the center. When they plotted the ASA vs length of fragment they found a power law and each amino acid had its own exponent. The more negative the exponent the smaller the ASA and thus the more hydrophobic the residue. The (negative) exponent could then be used as a hydropathy score. It differs from other scores in that it is not calculated in isolation based on chemical properties but accounts for the background of the amino acid.
M and Z’s score blew Jim’s mind because power laws are indicative of critical phenomena and phase transitions. Jim computed the coarse-grained hydropathy score (over a window of 35 residues) at each residue of a protein for a number of protein families. When COVID came along he naturally applied it to coronaviruses. He found that the coarse-grained hydropathy score profile of the spike protein of SARS-CoV-1 and SARS-CoV-2 had several deep hydrophobic wells. The well depths were nearly equal with SARS-CoV-2 being more equal than SARS-CoV-1. He then hypothesized that there was a selection advantage for well-depth symmetry and evolutionary pressure had pushed the SARS-CoV-2 spike to be near optimal. He argues that the symmetry allows the protein to coordinate activity better much like the way oscillators synchronize easier if their frequencies are more uniform. He predicted that given this optimality the spike was fragile and thus spike vaccines would be highly effective and that spike mutations could not change the spike much without diminishing function.
My contribution was to write some Julia code to automate this computation and apply it to some SARS-CoV-2 variants. I also scanned window sizes and found that the well depths are most equal close to Jim’s original value of 35. Below is Figure 3 from the paper.
What you see is the coarse-grained hydropathy score of the spike protein which is a little under 1300 residues long. Between residue 400 and 1200 there are 6 hydropathic wells. The well depths are more similar for SARS-CoV-2 and variants than SARS-CoV-1. Omicron does not look much different from the wild type, which makes me think that Omicron’s increased infectiousness is probably due to mutations that affect viral growth and transmission rather than spike binding to ACE2 receptors.
Jim is encouraging (strong arming) me into pushing this further, which I probably will given that there are still so many unanswered questions as to how and why it works, if at all. If anyone is interested in this, please let me know.
# Talk at Howard
Here are the slides for my talk at the “Howard University Math-Bio Virtual Workshop on Mitigation of Future Pandemics” last Saturday. One surprising thing (to me) the model predicted, shown on slide 40, is that the median fraction of those previously infected or vaccinated (or both) was 40% or higher during the omicron wave. I was pleased and relieved to then find that recent CDC serology results validate this prediction.
# Reorganizing risk in the age of disaster
I’ve been thinking a lot about what we should do for the next (and current) disaster. The first thing to say is that I am absolutely positively sure that I could not have done any better than what had been done for Covid-19. I probably would have done things differently but I doubt it would have led to a better (and probably a worse) outcome. I still think in aggregate, we are doing about as well as we could have. The one thing I do think we need to do is to figure out a way to partition risk. The biggest problem of the current pandemic is that people do not realize or care that their own risky behavior puts other people at risk. I do not care if a person wants to jump off of a cliff in a bat suit because they are mostly taking the risk upon themselves (although they do take up a bed in an ER ward if they get injured). However, not wearing a mask or getting vaccinated puts other people, including strangers, at risk. If you knowingly attend a wedding with a respiratory illness then you have the potential to infect tens if not hundreds of people and killing a fraction of them.
I do think people should be allowed to take risks as long as there are limited consequences to others. Thus, in a pandemic I think we should figure out a way for people to not get vaccinated or wear masks without affecting others. Currently, the main bottleneck is the health care system. If we allow people to wantonly get infected then there is a risk that they overwhelm hospitals. This affects all people who may need healthcare. Now is not a good time to try to repair your roof because if you fall you may not be able to get a bed in an ER ward. Thus, we really do need to think about stratifying health care according to risk acceptance. People who choose to lead risky lives should get to the back of the line when it comes to treatment. These policies should be made clear. Those who refuse to be vaccinated should just sign a form that they could be delayed in receiving health care. If you want to attend a large gathering then you should sign the same waiver.
I think that people should be allowed to opt out of the Nanny State but they need to absorb the consequences. I personally like to live in a highly regulated state but I think people should have a choice to opt out. They can live in a flood zone if they wish but they should not be bailed out after the flood. If banks want to participate in risky activities then fine but we should not bail them out. We should have let every bank fail after the 2008 crisis. We could have just let them all go under and saved homeowners instead (who should have been made better aware of the risks they were taking). Bailing out banks was a choice not a necessity.
# The dynamics of breakthrough infections
In light of the new omicron variant and breakthrough infections in people who have been vaccinated or previously infected, I was asked to discuss what a model would predict. The simplest model that includes reinfection is an SIRS model, where R, which stands for recovered, can become susceptible again. The equations have the form
$\frac{dS}{dt} = -\frac{\beta}{N} SI + \rho R$
$\frac{dI}{dt} = \frac{\beta}{N} SI - \sigma_R I$
$\frac{dR}{dt} = \sigma_RI - \rho R$
I have ignored death due to infection for now. So like the standard SIR model, susceptible, S, have a chance of being infected, I, if they contact I. I then recovers to R but then has a chance to become S again. Starting from an initial condition of S = N and I very small, then S will decrease as I grows.
The first thing to note that the number of people N is conserved in this model (as it should be). You can see this by noting that the sum of the right hand sides of all the equations is zero. Thus $\frac{dS}{dt} + \frac{dI}{dt} + \frac{dR}{dt} = 0$ and thus the integral is a constant and given that we started with N people then there will remain N people. This will change if we include births and deaths. Given this conservation law, then the dynamics have three possibilities. The first is that it goes to a fixed point meaning that in the long run the numbers of S, I and R will stabilize to some fixed number and remain there forever. The second is that it oscillates so S, I, and R will go up and down. The final one is that the orbit is chaotic meaning that S, I and R will change unpredictably. For these equations, the answer is the first option. Everything will settle to a fixed point.
To show this, you first must find an equilibrium or fixed point. You do this by setting all the derivatives to zero and solving the remaining equations. I have always found the fixed point to be the most miraculous state of any dynamical system. In a churning sea where variables move in all directions, there is one place that is perfectly still. The fixed point equations satisfy
$0 = -\frac{\beta}{N} SI + \rho R$
$0 = \frac{\beta}{N} SI - \sigma_R I$
$0 = \sigma_RI - \rho R$
There is a trivial fixed point given by S = N and I = R = 0. This is the case of no infection. However, if $\beta$ is large enough then this fixed point is unstable and any amount of I will grow. Assuming I is not zero, we can find another fixed point. Divide I out of the second equation and get
$S_0 = \frac{\sigma_R N}{\beta}$
Solving the third equation gives us
$R_0 = \frac{\sigma_R}{\rho} I_0$
which we can substitute into the first equation to get back the second equation. So to find I, we need to use the conservation condition S + I + R = N which after substituting for S and R gives
$I_0 = \frac{N(1-\sigma_R/\beta)}{1+\sigma_R/\rho} = \frac{\rho N(1-\sigma_R/\beta)}{\rho+\sigma_R}$
which we then back substitute to get
$R_0 = \frac{\sigma_R N(1-\sigma_R/\beta)}{\rho+\sigma_R}$
The fact that $I_0$ and $R_0$ must be positive implies $\beta > \sigma_R$ is necessary.
The next question is whether this fixed point is stable. Just because a fixed point exists doesn’t mean it is stable. The classic example is a pencil balancing on its tip. Any small perturbation will knock it over. There are many mathematical definitions of stability but they essentially boil down to – does the system return to the equilibrium if you move away from it. The most straightforward way to assess stability is to linearize the system around the fixed point and then see if the linearized system grows or decays (or stays still). We linearize because linear systems are the only types of dynamical systems that can always be solved systematically. Generalizable methods to solve nonlinear systems do not exist. That is why people such as myself can devote a career to studying them. Each system is its own thing. There are standard methods you can try to use but there is no recipe that will always work.
To linearize around a fixed point we first transform to a coordinate system around that fixed point by defining $S = S_0 + s$, $I = I_0 + h$, $R = R_0 + r$, to get
$\frac{ds}{dt} = -\frac{\beta}{N} (S_0h + I_0s +hs) + \rho r$
$\frac{dh}{dt} = \frac{\beta}{N}(S_0h + I_0s +hs)- \sigma_R h$
$\frac{dr}{dt} = \sigma_Rh - \rho r$
So now s = h = r = 0 is the fixed point. I used lower case h because lower case i is usually $\sqrt{-1}$. The only nonlinear term is $h s$, which we ignore when we linearize. Also by the definition of the fixed point $S_0$ the system then simplifies to
$\frac{ds}{dt} = -\frac{\beta}{N} I_0s - \sigma_R h + \rho r$
$\frac{dh}{dt} = \frac{\beta}{N}I_0 s$
$\frac{dr}{dt} = \sigma_Rh - \rho r$
which we can write as a matrix equation
$\frac{dx}{dt} = M x$, where $x = (S, I, R)$ and $M = ( -\beta/N I_0, -\sigma_R, \rho; \beta/N I_0, 0 , 0; 0, \sigma_R, -\rho)$. The trace of the matrix is $- \beta/N I_0 - \rho < 0$ so the sum of the eigenvalues is negative but the determinant is zero (since the rows sum to zero), and thus the product of the eigenvalues is zero. With a little calculation you can show that this system has two eigenvalues with negative real part and one zero eigenvalue. Thus, the fixed point is not linearly stable but could still be nonlinearly stable, which it probably is since the nonlinear terms are attracting.
That was a lot of tedious math to say that with reinfection, the simplest dynamics will lead to a stable equilibrium where a fixed fraction of the population is infected. The fraction increases with increasing $\beta$ or $\rho$ and decreases with $\sigma_R$. Thus, as long as the reinfection rate is much smaller than the initial infection rate (which it seems to be), we are headed for a situation where Covid-19 is endemic and will just keep circulating around forever. It may have a seasonal variation like the flu, which is still not well understood and is beyond the simple SIRS equation. If we include death in the equations then there is no longer a nonzero fixed point and the dynamics will just leak slowly towards everyone dying. However, if the death rate is slow enough this will be balanced by births and deaths due to other causes.
# Autocracy and Star Trek
Like many youth of my generation, I watched the original Star Trek in reruns and Next Generation and Deep Space Nine in real time. I enjoyed the shows but can’t really claim to be a Trekkie. I was already in graduate school when Next Generation began so I could not help but to scrutinize the shows for scientific accuracy. I was impressed that the way they discovered life in a baby universe created in one episode was by detecting localized entropy reduction, which is quite sophisticated scientifically. I bristled each time the star ship was on the brink of total failure and about to explode but the artificial gravity system still didn’t fail. I celebrated the one episode that actually had an artificial gravity failure and people actually floated in space! I thought it was ridiculous that almost every single planet they visited was always at room temperature with a breathable atmosphere. That doesn’t even describe many parts of earth. I mostly let these inaccuracies slide in the interest of story but I could never let go of one thing that always left me feeling somewhat despondent about the human condition, which was that even in a supposed super advanced egalitarian democratic society where material shortages no longer existed, Star Fleet was still an absolute autocracy. Many of the episodes dealt with strictly obeying the chain of command and never disobeying direct orders. A world with a democratic federation of planets, transporters and faster than light travel still believed that autocracy was the most efficient way to run an organization.
For most people throughout history and including today, the difference between autocracy and democracy is mostly abstract. People go to jobs where a boss tells them what to do. Virtually no one questions that corporations should be run autocratically. Authoritarian CEO’s are celebrated. Religion is generally autocratic. It only makes sense that the military backs autocrats given that autocracy is already the governing principle of their enterprise. Julius Caesar crossed the Rubicon and became the Dictator of Rome (he was never actually made Emperor) because he had the biggest army and it was loyal to him, not the Roman Republic. The only real question is how democracies even persist. People may care about freedom but do they really care all that much about democracy?
# My immune system
One outcome of the pandemic is that I have not had any illness (knock on wood), nary a cold nor sniffle, in a year and a half. On the other hand, my skin has fallen apart. I am constantly inflamed and itchy. I have no proof that the two are connected but my working hypothesis is that my immune system is hypersensitive right now because it has had little to do since the spring of 2020. It now overreacts to every mold spore, pollen grain, and speck of dust it runs into. The immune system is extremely complex, perhaps as complex as the brain. Its job is extremely difficult. It needs to recognize threats and eliminate them while not attacking itself. The brain and the immune system are intricately linked. How many people have gotten ill immediately after a final exam or deadline? The immune system was informed by the brain to delay action until the task was completed. The brain probably takes cues form the immune system too. One hypothesis for why asthma and allergies have been on the rise recently is that modern living has eliminated much contact with parasites and infectious agents, making the immune system hypersensitive. I for one, always welcome vaccinations because it gives my immune system something to do. In fact, I think it would be a good idea to get inoculations of all types regularly. I would take a vaccine for tape worm in a heartbeat. We are now slowly exiting from a global experiment in depriving the immune system of stimulation. We have no idea what the consequences will be. That is not to say that quarantine and isolation was not a good idea. Being itchy is clearly better than being infected by a novel virus (or being dead). There can be long term effects of infection too. Long covid is likely to be due to a miscalibrated immune system induced by the infection. Unfortunately, we shall likely never disentangle all the effects of COVID-19. We will not ever truly know what the long term consequences of infection, isolation, and vaccination will be. Most people will come out of this fine but a small fraction will not and we will not know why.
# RNA
The central dogma of molecular biology is that genetic information flows from DNA to RNA to proteins. All of your genetic material starts as DNA organized in 23 pairs of chromosomes. Your cells will under various conditions transcribe this DNA into RNA, which is then translated into proteins. The biological machinery that does all of this is extremely complex and not fully understood and part of my research is trying to understand this better. What we do know is that transcription is an extremely noisy and imprecise process at all levels. The molecular steps that transcribe DNA to RNA are stochastic. High resolution images of genes in the process of transcription show that transcription occurs in random bursts. RNA is very short-lived, lasting between minutes to at most a few days. There is machinery in the cell dedicated to degrading RNA. RNA is spliced; it is cut up into pieces and reassembled all the time and this splicing happens more or less randomly. Less than 2% of your DNA codes for proteins but virtually all of the DNA including noncoding parts are continuously being transcribed into small RNA fragments. Your cell is constantly littered with random stray pieces of RNA, and only a small fraction of it gets translated into proteins. Your RNA changes. All. The. Time.
Now, a more plausible alarmist statement (although still untrue) would be to say that vaccines change your DNA, which could be a bad thing. Cancer after all involves DNA mutations. There are viruses (retroviruses) that insert a copy of its RNA code into the host’s DNA. HIV does this for example. In fact, a substantial fraction of the human genome is comprised of viral genetic material. Changing proteins can also be very bad. Prion diseases are basically due to misfolded proteins. So DNA changing is not good, protein changing is not good, but RNA changing? Nothing to see here.
# COVID, COVID, COVID
Even though Covid-$\infty$ is going to be with us forever, I actually think on the whole the pandemic turned out better than expected, and I mean that in the technical sense. If we were to rerun the pandemic over and over again, I think our universe will end up with fewer deaths than average. That is not to say we haven’t done anything wrong. We’ve botched up many things of course but given that the human default state is incompetence, we botched less than we could have.
The thing we got right was in producing effective vaccines. That was simply astonishing. There had never been a successful mRNA-based drug of any type until the BioNTech and Moderna vaccines. Many things had to go right for the vaccines to work. We needed a genetic sequence (Chinese scientists made it public in January), from that sequence we needed a target (the coronavirus spike protein), we needed to be able to stabilize the spike (research that came out of the NIH vaccine center), we needed to make mRNA less inflammatory (years of work especially at Penn), we needed a way to package that mRNA (work out of MIT), and we needed a sense of urgency to get it done (Western governments). Vaccines don’t always work but we managed to get one in less than a year. So many things had to go right for that to happen. The previous US administration should be taking a victory lap because it was developed under their watch, instead of bashing it.
As I’ve said before, I am skeptical we can predict what will happen next but I am going to predict now that there will not be a variant in the next year that will escape from our current vaccines. We may need booster shots and minor tweaks but the vaccines will continue to work. Part of my belief stems from the work of JC Phillips who argues that the SARS-CoV-2 spike protein is already highly optimized and thus there is not much room for it to change and to become infectious. The virus may mutate to replicate faster within the body but the spike will be relatively stable and thus remain a target for the vaccines. The delta variant wave we’re seeing now is a pandemic of the unvaccinated. I have no idea if those against vaccinations will have a change of heart but at some point everyone will be infected and have some immune protection. (I just hope they approve the vaccine for children before winter). SARS-CoV-2 will continue to circulate just like the way the flu strain from the 1918 pandemic still circulates but it won’t be the danger and menace it is now.
# The Hash, the Merkle Tree, and Bitcoin
Although cryptocurrencies have been mainstream for quite a while, I still think the popular press has not done a great job explaining the details of how they work. There are several ideas behind a cryptocurrency like Bitcoin but the main one is the concept of a cryptographic hash. In simple terms, a hash is a way to transform an input sequence of characters (i.e. a string) into an output string such that it is hard to recreate the input string from the output string. A transformation with this property is called a one-way function. It is a machine where you get an output from an input but you can’t get the input from the output and there does not exist any other machine that can get the input from the output. A hash is a one-way function where the output has a standard form, e.g. 64 characters long. So if each character is a bit, e.g. 0 or 1, then there are $2^{64}$ different possible hashes. What makes hashes useful are two properties. The first, as mentioned, is that it is a one-way function and the second is that two different inputs do not give the same hash, called collision avoidance. There have been decades of work on figuring out how to do this and institutions like the US National Institutes of Standards and Technology (NIST) actually publish hash standards like SHA-2.
Now, one of the problems with hashing is that you need to deal with inputs of various sizes but you want the output to have a single uniform size. So even though a hash could have enough information capacity (i.e. entropy) to encode all of the world’s information ten times over, it is computationally inconvenient to just feed the complete text of Hamlet directly into a single one-way function. This is where the concept of a Merkle tree becomes important. You start with some one-way function that takes inputs of some fixed length and it scrambles the characters in some way that is not easily reversible. If the input string is too short then you just add extra characters (called padding) but if it is too long you need to do something else. The way a Merkle tree works is to break the text into chunks of uniform size. It then hashes the first chunk, adds that to the next chunk, hash the result and repeat until you have included all the chunks. This repeated recursive hashing is the secret sauce of crypto-currencies.
Bitcoin tried to create a completely decentralized digital currency that could be secure and trusted. For a regular currency like the US dollar, the thing you are most concerned about is that the dollar you receive is not counterfeit. The way that problem is solved is to make the manufacturing process of dollar bills very difficult to reproduce. So the dollar uses special paper with special marks and threads and special fonts and special ink. There are laws against making photocopiers with a higher resolution than the smallest print on a US bill to safeguard against counterfeiting. A problem with digital currencies is that you need to prevent double spending. The way this is historically solved is to have all transactions validated by a central authority.
Bitcoin solves these problems in a decentralized system by using a public ledger, called a blockchain that is time stamped, immutable and verifiable. The block chain keeps track of every Bitcoin transaction. So if you wanted to transfer one Bitcoin to someone else then the blockchain would show that your private Bitcoin ID has one less Bitcoin and the ID of the person you transferred to would have one extra Bitcoin. It is called a blockchain because each transaction (or set of transactions) is recorded into a block, the blocks are sequential, and each block contains a hash of the previous block. To validate a transaction you would need to validate each transaction leading up to the last block to validate that the hash on each block is correct. Thus the blockchain is a Merkle tree ledger where each entry is time stamped, immutable, and verifiable. If you want to change a block you need to change all the blocks before it.
However, the blockchain is not decentralized on its own. How do you prevent two blocks with two different hashes? The way to achieve that goal is to make the hash used in each block have a special form that is hard to find. This underlies the concept of “proof of work”. Bitcoin uses a hash called SHA-256 which consists of a hexadecimal string of 64 characters (i.e. a base 16 number, usually with characters consisting of the digits 0-9 plus letters a-f). Before each block gets added to the chain, it must have a hash that has a set number of zeros at the front. In order to do this, you need to add some random numbers to the block or rearrange it so that the hash changes. This is what Bitcoin miners do. They try different variations of the block until they get a hash that has a certain number of zeros in front and then they race to see who gets it first. The more zeros you need the more guesses you need and thus the harder the computation. If it’s just one zero then one in 16 hashes will have that property and thus on average 16 tries will get you the hash and the right to add to the blockchain. Each time you require an additional zero, the number of possibilities decreases by a factor of 16 so it is 16 times harder to find one. Bitcoin wants to keep the computation time around 15 minutes so as computation speed increases it just adds another zero. The result is an endless arms race. The faster the computers get the harder the hash is to find. The incentive for miners to be fast is that they get some Bitcoins if they are successful in being the first to find a desired hash and earning the right to add a block to the chain.
The actual details for how this works is pretty complicated. All the miners (or Bitcoin nodes) must validate that the proposed block is correct and then they all must agree to add that to the chain. The way it works in a decentralized way is that the code is written so that a node will follow the longest chain. In principle, this is secure because a dishonest miner who wants to change a previous block must change all blocks following it and thus as long as there are more honest miners than dishonest ones, the dishonest ones can never catch up. However, there are issues when two miners simultaneously come up with a hash and they can’t agree on which to follow. This is called a fork and has happened at least once I believe. This gets fixed eventually because honest miners will adopt the longest chain and the chain with the most adherents will grow the fastest. However, in reality there are only a small number of miners that regularly add to the chain so we’re at a point now where a dishonest actor could possibly dominate the honest ones and change the blockchain. Proof of work is also not the only way to add to a blockchain. There are several creative ideas to make it less wasteful or even make all that computation useful and I may write about them in the future. I’m somewhat skeptical about the long term viability of Bitcoin per se but I think the concepts of the blockchain are revolutionary and here to stay.
2021-06-21: some typos fixed and clarifying text added.
# Magic card tricks
Interesting article in the New York Times today about how people to this day still do not know how magician David Berglass did his “Any Card At Any Number” trick. In this trick, a magician asks a person or two to name a card (e.g. Queen of Hearts) and a number (e.g. 37) and then in a variety of ways produce a deck where that card appears at that order in the deck. The supposed standard way to do the trick is for the magician to manipulate the cards in some way but Berglass does his trick by never touching the cards. He can even do the trick impromptu when you visit him by leading you to a deck of cards somewhere in the room or from his pocket that has the card in the correct place. Now, I have no idea how he or anyone does this trick but one way to do the trick is to use “full enumeration”, i.e. hide decks where every possibility is accounted for and then the trick is to remember which deck has that choice. So then the question is how many decks would you need? Well the minimal number of decks is 52 because a particular card could be in one of 52 positions. But how many more decks would you need? The answer is zero. 52 is all you need because for any particular arrangement of cards, each card is in one position. Then all you do is rotate all the cards by one, so the card in the first position is now in the second position for deck 2 and 52 moves to 1 and so on. What the magician can do is to then hide 52 decks and remember the order of each deck. In the article he picked the reporter’s card to within 1 but claimed he may only be able to do it to within 2. That means he’s hiding the decks in groups of 3 and 4 say and then points you to that location and lets you choose which deck.
# The myth of the heroic entrepreneur
I sometimes listen to the podcast “How I built this“, where host Guy Raz interviews successful entrepreneurs like Herb Kelleher, who founded Southwest Airlines, Reid Hoffman of Linkedin, Stacy Madison of Stacy’s Pita Chips, and so on. The story arc of each interview is similar – some scrappy undervalued person comes up with a novel idea and then against all odds succeeds by hard work, unrelenting drive, and taking risks. The podcast fully embraces the American myth of the hero entrepreneur although Guy tries to do his best to extend it beyond the stereotypical Silicon Valley one typified by Steve Jobs or Elon Musk. At the end of each interview Guy will ask the subject how much of their success was due to luck and how much due to their ingenuity and diligence. Most are humble or savvy enough to say that some large fraction of the success was luck. While I have no doubt that each successful entrepreneur is bright, hard working, and possesses unique skills, there are countless others who are equally talented and yet did not succeed. Each success story is an example of survivor bias. We sometimes hear about spectacular failures, like the Edsel , but rarely do we hear about the story of “How I almost built this”.
There is a stock market scam where you email blocks of 1024 prospective marks a prediction of what a stock will do that week. For one half, you say the stock will go up and for the other half you say it will go down. Then for the half for which you were correct, you do the same thing and half of them (one quarter of the original) will receive a correct prediction. Finally after ten weeks, one of the original 1024 will have received 10 correct predictions in a row and think that you are either a genius or have inside information and will be primed to sign up for whatever scam you are selling. The lucky (or unlucky) person is fooled because they lack the information that 1023 others did not receive perfect predictions. Obviously, this also works for sports predictions.
While, I think most success is luck there do seem to be outliers. Elon Musk seems to be one. He manages to invent new industries and succeed with regularity. Warren Buffet does seem to be able to beat the market. However, it is for us as a society to decide how winners should be rewarded. In many industries there is a winner-take-all dynamic, where the larger you get the easier it is to crush the competition. Mark Zuckerberg is clearly skilled but Facebook is dominant right now because it is a monopolist; it simply buys up as many competitors as it can. The same goes for Google, Amazon, and AT&T until the government broke it up. Finance works that way too. The bigger a bank or hedge fund gets, the easier it is to succeed. A small fluctuation that propels one firm a little ahead of the rest at the right time will be exponentially amplified. While, I do think it is a positive thing to reward success I don’t think the reward needs to be so disparate. Right now, a very small difference in ability (or none at all) and a lot of luck can be the difference between flying to your house in the Hamptons in a helicopter or selling hotdogs from a cart on Fifth Avenue.
# The final stretch
The end of the Covid-19 pandemic is within reach. The vaccines have been a roaring success and former Bell Labs physicist J.C. Phillips predicted it (see here). He argued that the spike protein, which is the business end of the SARS-CoV-2 virus, has been optimized to such a degree in SARS-CoV-2 that even a small perturbation from a vaccine can disrupt it. While the new variants perturb the spike slightly and seem to spread faster, they will not significantly evade the vaccine. However, just because the end is within sight doesn’t mean we should not still be vigilante and not mess this up. Europe has basically scored multiple own goals these past few months with their vaccine rollout (or lack thereof) that is a combination of both gross incompetence and excessive conservatism. The Astra-Zeneca vaccine fiasco was a self-inflicted wound by all parties involved. The vaccine is perfectly fine and any side effects are either not related to the vaccine or of such low probability that it should not be a consideration for halting its use. By artificially slowing vaccine distribution, there is a chance that some new mutation could arise that will evade the vaccine. Europe needs to get its act in gear. The US has steadily ramped up vaccinations and is on course to have all willing adults vaccinated by start of summer. Although there has been a plateauing and even slight rise recently because of relaxation from social distancing in some areas, cases and deaths will drop for good by June everywhere in the US. North America will largely be back to normal by mid-summer. However, it is imperative that we press forward and vaccinate the entire world. We will also all need to get booster shots next fall when we get our flu shots.
# The probability of extraterrestrial life
Since, the discovery of exoplanets nearly 3 decades ago most astronomers, at least the public facing ones, seem to agree that it is just a matter of time before they find signs of life such as the presence of volatile gases in the atmosphere associated with life like methane or oxygen. I’m an agnostic on the existence of life outside of earth because we don’t have any clue as to how easy or hard it is for life to form. To me, it is equally possible that the visible universe is teeming with life or that we are alone. We simply do not know.
But what would happen if we find life on another planet. How would that change our expected probability for life in the universe? MIT astronomer Sara Seager once made an offhand remark in a podcast that finding another planet with life would make it very likely there were many more. But is this true? Does the existence of another planet with life mean a dramatic increase in the probability of life in the universe. We can find out by doing the calculation.
Suppose you believe that the probability of life on a planet is $f$ (i.e. fraction of planets with life) and this probability is uniform across the universe. Then if you search $n$ planets, the probability for the number of planets with life you will find is given by a Binomial distribution. The probability that there are $x$ planets is given by the expression $P(x | f) = C(x,n) f^x(1-f)^{n-x}$, where $C$ is a factor (the binomial coefficient) such that the sum of $x$ from one to $n$ is 1. By Bayes Theorem, the posterior probability for $f$ (yes, that would be the probability of a probability) is given by
$P(f | x) = \frac{ P(x | f) P(f)}{P(x)}$
where $P(x) = \int_0^1 P(x | f) P(f) df$. As expected, the posterior depends strongly on the prior. A convenient way to express the prior probability is to use a Beta distribution
$P(f |\alpha, \beta) = B(\alpha,\beta)^{-1} f^{\alpha-1} (1-f)^{\beta-1}$ (*)
where $B$ is again a normalization constant (the Beta function). The mean of a beta distribution is given by $E(f) = \alpha/(\alpha + \beta)$ and the variance, which is a measure of uncertainty, is given by $Var(f) = \alpha \beta /(\alpha + \beta)^2 (\alpha + \beta + 1)$. The posterior distribution for $f$ after observing $x$ planets with life out of $n$ will be
$P(f | x) = D f^{\alpha + x -1} (1-f)^{n+\beta - x -1}$
where $D$ is a normalization factor. This is again a Beta distribution. The Beta distribution is called the conjugate prior for the Binomial because it’s form is preserved in the posterior.
Applying Bayes theorem in equation (*), we see that the mean and variance of the posterior become $(\alpha+x)/(\alpha + \beta +n)$ and $(\alpha+x)( \beta+n-x) /(\alpha + \beta + n)^2 (\alpha + \beta + n + 1)$, respectively. Now let’s consider how our priors have updated. Suppose our prior was $\alpha = \beta = 1$, which gives a uniform distribution for $f$ on the range 0 to 1. It has a mean of 1/2 and a variance of 1/12. If we find one planet with life after checking 10,000 planets then our expected $f$ becomes 2/10002 with variance $2\times 10^{-8}$. The observation of a single planet has greatly reduced our uncertainty and we now expect about 1 in 5000 planets to have life. Now what happens if we find no planets. Then, our expected $f$ only drops to 1 in 10000 and the variance is about the same. So, the difference between finding a planet versus not finding a planet only halves our posterior if we had no prior bias. But suppose we are really skeptical and have a prior with $\alpha =0$ and $\beta = 1$ so our expected probability is zero with zero variance. The observation of a single planet increases our posterior to 1 in 10001 with about the same small variance. However, if we find a single planet out of much fewer observations like 100, then our expected probability for life would be even higher but with more uncertainty. In any case, Sara Seager’s intuition is correct – finding a planet would be a game breaker and not finding one shouldn’t really discourage us that much.
# The inherent conflict of liberalism
Liberalism, as a philosophy, arose during the European Enlightenment of the 17th century. It’s basic premise is that people should be free to choose how they live, have a government that is accountable to them, and be treated equally under the law. It was the founding principle of the American and French revolutions and the basic premise of western liberal democracies. However, liberalism is inherently conflicted because when I exercise my freedom to do something (e.g. not wear a mask), I infringe on your freedom from the consequence of that thing (e.g. not be infected) and there is no rational resolution to this conflict. This conflict led to the split of liberalism into left and right branches. In the United States, the term liberal is exclusively applied to the left branch, which mostly focuses on the ‘freedom from’ part of liberalism. Those in the right branch, who mostly emphasize the ‘freedom to’ part, refer to themselves as libertarian, classical liberal, or (sometimes and confusingly to me) conservative. (I put neo-liberalism, which is a fundamentalist belief in free markets, into the right camp although it has adherents on both the left and right.) Both of these viewpoints are offspring of the same liberal tradition and here I will use the term liberal in the general sense.
Liberalism has never operated in a vacuum. The conflicts between “freedom to” and “freedom from” have always been settled by prevailing social norms, which in the Western world was traditionally dominated by Christian values. However, neither liberalism nor social norms have ever been sufficient to prevent bad outcomes. Slavery existed and was promoted by liberal Christian states. Genocide of all types and scales have been perpetrated by liberal Christian states. The battle to overcome slavery and to give equal rights to all peoples was a long and hard fought battle over slowly changing social norms rather than laws per se. Thus, while liberalism is the underlying principle behind Western governments, it is only part of the fabric that holds society together. Even though we have just emerged from the Dark Years, Western Liberalism is on its shakiest footing since the Second World War. The end of the Cold War did not bring on a permanent era of liberal democracy but may have spelled it’s eventual demise. What will supplant liberalism is up to us.
It is often perceived that the American Democratic party is a disorganized mess of competing interests under a big tent while the Republicans are much more cohesive but in fact the opposite is true. While the Democrats are often in conflict they are in fact a fairly unified center-left liberal party that strives to advocate for the marginalized. Their conflicts are mostly to do with which groups should be considered marginalized and prioritized. The Republicans on the other hand are a coalition of libertarians and non-liberal conservatives united only by their desire to minimize the influence of the federal government. The libertarians long for unfettered individualism and unregulated capitalism while the conservatives, who do not subscribe to all the tenets of liberalism, wish to halt encroaching secularism and a government that no longer serves their interests.
The unlikely Republican coalition that has held together for four decades is now falling apart. It came together because the more natural association between religious conservatism and a large federal bureaucracy fractured after the Civil Rights movements in the 1960’s when the Democrats no longer prioritized the concerns of the (white) Christian Right. (I will discuss the racial aspects in a future post). The elite pro-business neo-liberal libertarians could coexist with the religious conservatives as long as their concerns did not directly conflict but this is no longer true. The conservative wing of the Republican party have discovered their new found power and that there is an untapped population of disaffected individuals who are inclined to be conservative and also want a larger and more intrusive government that favors them. Prominent conservatives like Adrian Vermeule of Harvard and Senator Josh Hawley are unabashedly anti-liberal.
This puts the neo-liberal elites in a real bind. The Democratic party since Bill Clinton had been moving right with a model of pro-market neo-liberalism but with a safety net. However they were punished time and time again by the neo-liberal right. Instead of partnering with Obama, who was highly favorable towards neoliberalism, they pursued a scorched earth policy against him. Hilary Clinton ran on a pretty moderate safety-net-neo-liberal platform and got vilified as an un-American socialist. Now, both the Republicans and Democrats are trending away from neo-liberalism. The neo-liberals made a strategic blunder. They could have hedged their bets but now have lost influence in both parties.
While the threat of authoritarianism looms large, this is also an opportunity to accept the limits of liberalism and begin to think about what will take its place – something that still respects the basic freedoms afforded by liberalism but acknowledges that it is not sufficient. Conservative intellectuals like Leo Strauss have valid points. There is indeed a danger of liberalism lapsing into total moral relativism or nihilism. Guardrails against such outcomes must be explicitly installed. There is value in preserving (some) traditions, especially ancient ones that are the result of generations of human engagement. There will be no simple solution. No single rule or algorithm. We will need to explicitly delineate what we will accept and what we will not on a case by case basis.
# The machine learning president
For the past four years, I have been unable to post with any regularity. I have dozens of unfinished posts sitting in my drafts folder. I would start with a thought but then get stuck, which had previously been somewhat unusual for me. Now on this first hopeful day I have had for the past four trying years, I am hoping I will be able to post more regularly again.
Prior to what I will now call the Dark Years, I viewed all of history through an economic lens. I bought into the standard twentieth century leftist academic notion that wars, conflicts, social movements, and cultural changes all have economic underpinnings. But I now realize that this is incorrect or at least incomplete. Economics surely plays a role in history but what really motivates people are stories and stories are what led us to the Dark Years and perhaps to get us out.
Trump became president because he had a story. The insurrectionists who stormed the Capitol had a story. It was a bat shit crazy lunatic story but it was still a story. However, the tragic thing about the Trump story (or rather my story of the Trump story) is that it is an unintentional algorithmically generated story. Trump is the first (and probably not last) purely machine learning president (although he may not consciously know that). Everything he did was based on the feedback he got from his Twitter Tweets and Fox News. His objective function was attention and he would do anything to get more attention. Of the many lessons we will take from the Dark Years, one should be how machine learning and artificial intelligence can go so very wrong. Trump’s candidacy and presidency was based on a simple stochastic greedy algorithm for attention. He would Tweet randomly and follow up on the Tweets that got the most attention. However, the problem with a greedy algorithm (and yes that is a technical term that just happens to coincidentally be apropos) is that once you follow a path it is hard to make a correction. I actually believe that if some of Trump’s earliest Tweets from say 2009-2014 had gone another way, he could have been a different president. Unfortunately, one of his early Tweet themes that garnered a lot of attention was on the Obama birther conspiracy. This lit up both racist Twitter and a counter reaction from liberal Twitter, which led him further to the right and ultimately to the presidency. His innate prejudices biased him towards a darker path and he did go completely unhinged after he lost the election but he is unprincipled and immature enough to change course if he had enough incentive to do so.
Unlike standard machine learning for categorizing images or translating languages, the Trump machine learning algorithm changes the data. Every Tweet alters the audience and the reinforcing feedback between Trump’s Tweets and its reaction can manufacture discontent out of nothing. A person could just happen to follow Trump because they like The Apprentice reality show Trump starred in and be having a bad day because they missed the bus or didn’t get a promotion. Then they see a Trump Tweet, follow the link in it and suddenly they find a conspiracy theory that “explains” why they feel disenchanted. They retweet and this repeats. Trump sees what goes viral and Tweets more on the same topic. This positive feedback loop just generated something out of random noise. The conspiracy theorizing then starts it’s own reinforcing feedback loop and before you know it we have a crazed mob bashing down the Capitol doors with impunity.
Ironically Trump, who craved and idolized power, failed to understand the power he actually had and if he had a better algorithm (or just any strategy at all), he would have been reelected in a landslide. Even before he was elected, Trump had already won over the far right and he could have started moving in any direction he wished. He could have moderated on many issues. Even maintaining his absolute ignorance of how govening actually works, he could have had his wall by having it be part of actual infrastructure and immigration bills. He could have directly addressed the COVID-19 pandemic. He would not have lost much of his base and would have easily gained an extra 10 million votes. Maybe, just maybe if liberal Twitter simply ignored the early incendiary Tweets and only responded to the more productive ones, they could have moved him a bit too. Positive reinforcement is how they train animals after all.
Now that Trump has shown how machine learning can win a presidency, it is only a matter of time before someone harnesses it again and more effectively. I just hope that person is not another narcissistic sociopath.
On some rare days when the sun is shining and I’m enjoying a well made kouign-amann (my favourite comes from b.patisserie in San Francisco but Patisserie Poupon in Baltimore will do the trick), I find a brief respite from my usual depressed state and take delight, if only for a brief moment, in the fact that mathematics completely resolved Zeno’s paradox. To me, it is the quintessential example of how mathematics can fully solve a philosophical problem and it is a shame that most people still don’t seem to know or understand this monumental fact. Although there are probably thousands of articles on Zeno’s paradox on the internet (I haven’t bothered to actually check), I feel like visiting it again today even without a kouign-amann in hand.
I don’t know what the original statement of the paradox is but they all involve motion from one location to another like walking towards a wall or throwing a javelin at a target. When you walk towards a wall, you must first cross half the distance, then half the remaining distance, and so on forever. The paradox is thus: How then can you ever reach the wall, or a javelin reach its target, if it must traverse an infinite number of intervals? This paradox is completely resolved by the concept of the mathematical limit, which Newton used to invent calculus in the seventeenth century. I think understanding the limit is the greatest leap a mathematics student must take in all of mathematics. It took mathematicians two centuries to fully formalize it although we don’t need most of that machinery to resolve Zeno’s paradox. In fact, you need no more than middle school math to solve one of history’s most famous problems.
The solution to Zeno’s paradox stems from the fact that if you move at constant velocity then it takes half the time to cross half the distance and the sum of an infinite number of intervals that are half as long as the previous interval adds up to a finite number. That’s it! It doesn’t take forever to get anywhere because you are adding an infinite number of things that get infinitesimally smaller. The sum of a bunch of terms is called a series and the sum of an infinite number of terms is called an infinite series. The beautiful thing is that we can compute this particular infinite series exactly, which is not true of all series.
Expressed mathematically, the total time $t$ it takes for an object traveling at constant velocity to reach its target is
$t = \frac{d}{v}\left( \frac{1}{2} + \frac{1}{4} + \frac{1}{8} + \cdots\right)$
which can be rewritten as
$t = \frac{d}{v}\sum_{n=1}^\infty \frac{1}{2^n}$
where $d$ is the distance and $v$ is the velocity. This infinite series is technically called a geometric series because the ratio of two subsequent terms in the series is always the same. The terms are related geometrically like the volumes of n-dimensional cubes when you have halve the length of the sides (e.g. 1-cube (line and volume is length), 2-cube (square and volume is area), 3-cube (good old cube and volume), 4-cube ( hypercube and hypervolume), etc) .
For simplicity we can take $d/v = 1$. So to compute the time it takes to travel the distance, we must compute:
$t = \frac{1}{2} + \frac{1}{4} + \frac{1}{8} + \frac{1}{16}\cdots$
To solve this sum, the first thing is to notice that we can factor out $1/2$ and obtain
$t = \frac{1}{2}\left(1 + \frac{1}{2} + \frac{1}{4} + \frac{1}{8}\cdots\right)$
The quantity inside the bracket is just the original series plus 1, i.e.
$1 + t = 1 + \frac{1}{2} + \frac{1}{4} + \frac{1}{8} + \frac{1}{16}\cdots$
and thus we can substitute this back into the original expression for $t$ and obtain
$t = \frac{1}{2}(1 + t)$
Now, we simply solve for $t$ and I’ll actually go over all the algebraic steps. First multiply both sides by 2 and get
$2 t = 1 +t$
Now, subtract $t$ from both sides and you get the beautiful answer that $t = 1$. We then have the amazing fact that
$t = \sum_{n=1}^\infty \frac{1}{2^n} = 1$
I never get tired of this. In fact this generalizes to any geometric series
$\sum_{n=1}^\infty \frac{1}{a^n} = \frac{1}{1-a} - 1$
for any $a$ that is less than 1. The more compact way to express this is
$\sum_{n=0}^\infty \frac{1}{a^n} = \frac{1}{1-a}$
Now, notice that in this formula if you set $a = 1$, you get $1/0$, which is infinity. Since $1^n= 1$ for any $n$, this tells you that if you try to add up an infinite number of ones, you’ll get infinity. Now if you set $a > 1$ you’ll get a negative number. Does this mean that the sum of an infinite number of positive numbers greater than 1 is a negative number? Well no because the series is only defined for $a < 1$, which is called the domain of convergence. If you go outside of the domain, you can still get an answer but it won’t be the answer to your question. You always need to be careful when you add and subtract infinite quantities. Depending on the circumstance it may or may not give you sensible answers. Getting that right is what math is all about.
# The fear is real
When I was in graduate school, my friends and I would jokingly classify the utility of research in terms of the order the researcher would be killed after the revolution. So, for physics, if you were working on say galaxy formation in the early universe you would be killed before someone working on the properties of hydrogen at low temperatures, who would be killed before someone working on building a fusion reactor. This was during the cold war and thus the prospect of Stalin and Mao still loomed large. We did not joke this way with fear or disdain but rather with a somewhat bemused acknowledgment that we were afforded the luxury to work on esoteric topics, while much of the world still did not have running water. In those days, the left-right divide was between the small government neoliberals (conservatives in those days who advocated for freer and more deregulated markets) and the bigger government New Deal liberals (those for more government action to address economic inequities). We certainly had fierce debates but they were always rather abstract. We never thought our lives would really change that much.
By the time I had finished and started my academic career, it was clear that the neoliberals had prevailed. The Soviet Union had collapsed, AT&T was broken up, and the Democratic president proclaimed the era of big government was over. Francis Fukuyama wrote “The End of History and the Last Man” arguing that western liberal democracy had triumphed over communism and would be the last form of government. I was skeptical then because I thought we could do better but I really didn’t consider that it could get worse.
But things got worse. We had the bursting of the dot com bubble, 9/11, the endless wars, the great recession, and now perhaps the twilight of democracy as Anne Applebaum laments in her most recent book. We can find blame everywhere – globalization, automation, the rise of China, out of touch elites, the greedy 1%, cynical politicians, the internet, social media, and so forth. Whatever the reason, this is an era where no one is happy and everyone is fearful.
The current divide in the United States is very real and there is fear on both sides. On one side, there is fear that an entire way of life is being taken away – a life of a good secure job, a nuclear family with well defined roles, a nice house, neighbors who share your values and beliefs, a government that mostly stays out of the way but helps when you are in need, the liberty to own a firearm, and a sense of community and shared sacrifice. On the other side, there is the fear that progress is being halted, that a minority will forever suppress a majority, that social, racial, and economic justice will never be achieved, that democracy itself is in peril, and that a better future will always be just out of reach.
What is most frustrating to me is that these points of view are not necessarily mutually exclusive. I don’t know how we can reconcile these differences but my biases and priors incline me to believe that we could alleviate some of the animosity and fear if we addressed income insecurity. While I think income inequality is a real problem, I think a more pressing concern is that a large segment of the population on both sides of the the divide lives continuously on a precipice of economic ruin, which has been made unavoidably apparent by our current predicament. I really think we need to consider a universal basic income. I also think it has to be universal because suspicion of fraud and resentment is a real issue. Everyone gets the check and those with sufficient incomes and wealth simply pay it back in taxes.
# How science dies
Nietzsche famously wrote:
This quote is often used as an example of Nietzsche’s nihilism but it is much more complicated. These words are actually spoken by a madman in Nietzsche’s book The Gay Science. According to philosopher Simon Critchley, the quote is meant to be a descriptive rather than a normative statement. What Nietzshe was getting at is that Christianity is a religion that values provable truth and as a result of this truth seeking, science arose. Science in turn generated skepticism of revealed truth and the concept of God. Thus, the end of Christianity was built into Christianity.
Borrowing from this analysis, science may also have have a built-in mechanism for its own doom. An excellent article in this month’s Technology Review describes the concept of epistemic dependence, where science and technology is so complicated now that no single person can understand all of it. In my own work, I could not reproduce a single experiment of my collaborators. Our collaborations work because we trust each other. I don’t really know how scientists identify new species of insects, or how paleontologists can tell what species a bone fragment belongs to, or all the details of the proof of the Poincare conjecture. However, I do understand how science and math works and trust that the results are based on those methods.
But what about people who are not trained in science? If you tell them that the universe was formed 14 billion years ago in a Big Bang and that 99% of all the stuff in the universe is completely invisible, why would they believe you. Why is that more believable then the earth being formed six thousand years ago in seven days? In both cases, knowledge is transferred to them from an authority. Sure you can say because of science, we live longer, have refrigerators, cell phones, and Netflix so we should believe scientists. On the other hand, a charismatic conman could tell them that they have those things because they were gifted from super advanced aliens. Depending on the sales job and one’s priors, it is not clear to me which would be more convincing.
So perhaps we need more science education? Well, in half a century of focus on science education, science literacy is not really very high in the general public. I doubt many people could explain how a refrigerator works much less the second law of thermodynamics and forget about quantum mechanics. Arthur C. Clarke’s third law that “All sufficiently advanced technology is indistinguishable from magic” is more applicable then ever. While it is true that science has delivered on producing better stuff it does not necessarily make us more fulfilled or happier. I can easily see a future where a large fragment of the population simply turns away from science with full knowledge of what they are doing. That would be the good outcome. The bad one is that people start to turn against science and scientists because someone has convinced them that all of their problems (and none of the good stuff) are due to science and scientists. They would then go and destroy the world as we know it without really intending to. I can see this happening too.
# Nobel Prize has outlived its usefulness
The Nobel Prize in Physiology was awarded for the discovery of Hepatitis C today. The work is clearly deserving of recognition but this is another case where there were definitely more than three people who played an essential role in the work. I really think that the Nobel Prize should change its rules to allow for more winners. Below is my post when one of the winners of this years prize, Michael Houghton, turned down the Gairdner Award in 2013:
Hepatitis C and the folly of prizes
The scientific world was set slightly aflutter when Michael Houghton turned down the prestigious Gairdner Award for the the discovery of Hepatitis C. Harvey Alter and Daniel Bradley were the two other recipients. Houghton, who had previously received the Lasker Award with Alter, felt he could not accept one more award because two colleagues Qui-Lim Choo and George Kuo did not receive either of these awards, even though their contributions were equally important.
Hepatitis, which literally means inflammation of the liver, was characterized by Hippocrates and known to be infectious since the 8th century. The disease had been postulated to be viral at the beginning of the 20th century and by the 1960’s two viruses termed Hepatitis A and Hepatitis B had been established. However, there still seemed to be another unidentified infectious agent which was termed Non-A Non-B Hepatitis NANBH.
Michael Hougton, George Kuo and Qui-Lim Choo were all working at the Chiron corporation in the early 1980’s. Houghton started a project to discover the cause of NANBH in 1982 with Choo joining a short time later. They made significant process in generating mouse monoclonal antibodies with some specificity to NANBH infected materials from chimpanzee samples received from Daniel Bradley at the CDC. They used the antibodies to screen cDNA libraries from infected materials but they had not isolated an agent. George Kuo had his own lab at Chiron working on other projects but would interact with Houghton and Choo. Kuo suggested that they try blind cDNA immunoscreening on serum derived from actual NANBH patients. This approach was felt to be too risky but Kuo made a quantitative assessment that showed it was viable. After two years of intensive and heroic screening by the three of them, they identified one clone that was clearly derived from the NANBH genome and not from human or chimp DNA. This was definitive proof that NANBH was a virus, which is now called Hepatitis C. Kuo then developed a prototype of a clinical Hepatitis C antibody detection kit and used it to screen a panel of NANBH blood provided by Harvey Alter of the NIH. Kuo’s test was a resounding success and the blood test that came out of that work has probably saved 300 million or more people from Hepititis C infection.
The question then is who deserves the prizes. Is it Bradley and Alter, who did careful and diligent work obtaining samples or is it Houghton, Choo, and Kuo, who did the heroic experiments that isolated the virus? For completely unknown reasons, the Lasker was awarded to just Houghton and Alter, which primed the pump for more prizes to these two. Now that the Lasker and Gairdner prizes have been cleared, that leaves just the Nobel Prize. The scientific community could get it right this time and award it to Kuo, Choo, and Houghton.
Addendum added 2013-5-2: I should add that many labs from around the world were also trying to isolate the infective agent of NANBH and all failed to identify the correct samples from Alter’s panel. It is not clear how long it would have been and how many more people would have been infected if Kuo, Choo, and Houghton had not succeeded when they did.
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https://www.physicsforums.com/threads/recommand-a-nice-qm-textbook-on-perturbation-and-scattering.421192/
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# Recommand a nice qm textbook on perturbation and scattering
1. Aug 9, 2010
### kof9595995
I just finished the first 4 chapters of Sakurai's Modern qm, and now I'm begining to learn purterbation method and scattering theory, but from the feedback it seems that many people are quite unsatisfied with Modern qm on these parts. Could you guys recommand a nice book on perturbation and scattering?
2. Aug 9, 2010
### humanino
I like "Scattering theory : the quantum theory of non-relativistic collisions" by John R. Taylor.
3. Aug 10, 2010
### kof9595995
Thanks for the information, btw does it also include perturbation theory ?
4. Aug 11, 2010
### humanino
Yes it does. It is not the fastest shortcut to perturbation and perturbation technologies are not applied to many examples. Rather, it is a formal text justifying rigorously the perturbation formalism, pointing out the subtleties and caveats.
5. Aug 23, 2010
### kof9595995
Thanks, just had a look at the content, it seems a bit too andvanced for me.
6. Aug 23, 2010
### Daverz
For scattering theory, Quantum Mechanics II: A Second Course in Quantum Theory by Rubin Landau is good.
Although, maybe what you need is a second QM text. Shankar, perhaps. Or at a more sophisticated level, the book by Arno Bohm.
Last edited: Aug 23, 2010
Similar Discussions: Recommand a nice qm textbook on perturbation and scattering
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http://boundedtheoretics.blogspot.com/2012_04_01_archive.html
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Thursday, April 26, 2012
Bob Marks grossly misunderstands “no free lunch”
And so does Bill Dembski. But it is Marks who, in a “Darwin or Design?” interview, reveals plainly the fallacy at the core of his and Dembski's notion of “active information.” (He gets going at 7:50. To select a time, it's best to put the player in full-screen mode. I've corrected slips of the tongue in my transcript.)
[The “no free lunch” theorem of Wolpert and Macready] said that with a lack of any knowledge about anything, that one search was as good as any other search. [14:15]
And what Wolpert and Macready said was, my goodness, none of these [“search”] algorithms work as well as [better than] any other one, on the average, if you have no idea what you're doing. And so the question is… and what we've done here is, if indeed that is true, and an algorithm works, then that means information has been added to the search. And what we've been able to do is take this baseline, that all searches are the same, and we've been able to, in cases where searches work, measure the information that is placed into the algorithm in bits. And we have looked at some of the evolutionary algorithms, and we found out that, strikingly, they are not responsible for any creation of information. [14:40]
And according to “no free lunch” theorems, astonishingly, any search, without information about the problem that you're looking for, will operate at the same level as blind search. And that's... It's a mind-boggling result. [28:10]
Bob has read into the “no free lunch” (NFL) theorems what he believed in the first place, namely that if something works, it must have been designed to do so. Although he gets off to a good start by referring to the subjective state of the practitioner (“with a lack of knowledge,” “if you have no idea what you're doing”), he errs catastrophically by making a claim about the objective state of affairs (“one search is as good as any other search,” “all searches are the same”).
Does your lack of knowledge about a problem imply that all available solution methods (algorithms) work equally well in fact? If you think so, then you're on par with the Ravenous Bugblatter Beast of Traal, “such a mind-bogglingly stupid animal, it assumes that if you can't see it, it can't see you.” Your lack of knowledge implies only that you cannot formally justify a choice of algorithm. There not only may be, but in practice usually will be, huge differences in algorithm performance.
What boggles my mind is that Marks and Dembski did not learn this from Wolpert and Macready (1997), “No Free Lunch Theorems for Optimization.” In Section III-A, the authors observe that “it is certainly true that any class of problems faced by a practitioner will not have a flat prior.” This means that some problems are more likely than others, and the NFL theorems do not hold in fact. So what is the significance of the theorems?
First, if the practitioner has knowledge of problem characteristics but does not incorporate them into the optimization algorithm, then... the NFL theorems establish that there are no formal assurances that the algorithm chosen will be at all effective. Second, while most classes of problems will certainly have some structure which, if known, might be exploitable, the simple existence of that structure does not justify choice of a particular algorithm; that structure must be known and reflected directly in the choice of algorithm to serve as such a justification. [emphasis mine]
So don't take my word for it that Bob has twisted himself into intellectual contortions with his apologetics. This comes from an article with almost 2600 citations. If memory serves, Marks and Dembski have cited it in all 7 of their publications.
Marks and Dembski believe, astonishingly, that the NFL theorems say that an algorithm outperforms “blind search” only if some entity has exploited problem-specific information in selecting it, when the correct interpretation is that the practitioner is justified in believing that an algorithm outperforms “blind search” only if he or she exploits problem-specific knowledge [justified true belief, not just information] in selecting it. This leads them to the fallacious conclusion that when a search $s$ outperforms blind search, they can measure the problem-specific information that an ostensible "search-forming process” added to $s$ to produce the gain in performance. They silently equate performance with information, and contrive to transform the gain in performance into an expression that looks like gain of Shannon information.
Their name-game depends crucially on making the outcome of a search dichotomous — absolute success (performance of 1) or absolute failure (performance of 0). Then the expected performance of a search is also its probability of success. There is a probability $p$ that blind search solves the problem, and a probability $p_s > p$ that search $s$ solves the problem, and the ratio $p_s / p$ is naturally interpreted as performance gain. But to exhibit the “added information” (information gain), Marks and Dembski do a gratuitous logarithmic transformation of the performance gain, $$I_+ = \log \frac{p_s}{p} = \log p_s - \log p = -\!\log p + \log p_s,$$ and call the result active information. (The last step is silly, of course. Evidently it makes things look more “Shannon information-ish.”) To emphasize, they convert performance into “information” by sticking to a special case in which expected performance is a probability.
Here's a simple (in)sanity check. Suppose that I have a “pet” algorithm that I run on all problems that come my way. Obviously, there's no sense in which I add problem-specific information. But Marks and Dembski cherry-pick the cases in which my algorithm outperforms blind search, and, because active information is by definition the degree to which an algorithm outperforms blind search, declare that something really did add information to the algorithm.
Now, a point I'll treat only briefly is that Marks and Dembski claim that the cases in which my pet algorithm greatly outperforms blind search are exceedingly rare. The fact is that they do not know the distribution of problems arising in the real world, and have no way of saying how rare or common extreme performance is for simple algorithms. In the case of computational search, we know for sure that the distribution of problems diverges fabulously from the uniform. Yet Marks and Dembski carry on about “Bernoulli's Principle of Insufficient Reason and Conservation of Information in Computer Search,” doing their damnedest to fob off subjective assignment of uniform probability as objective chance.
A bit of irony for dessert [35:50]:
Question: Are you getting any kind of response from the other side? Are they saying this is kind of interesting, or are they kind of putting stoppers in their ears? What's going on?
Answer: It's more of the stoppers in the ears thus far. We have a few responses on blogs, which are unpleasant, and typically personal attacks, so those are to be ignored. We're waiting for, actually, something substantive in response.
A note to reviewers of papers by Dembski and Marks
William A. Dembski and Robert J. Marks II lace their engineering papers with subtle insinuations that will strike reviewers as somewhat strange, but that probably will not raise red flags. The only publication in which they give a crystal-clear explanation of their measure of active information, and state outright what they're trying to do with it, is the somewhat philosophical Life's Conservation Law: Why Darwinian Evolution Cannot Create Biological Information. Note that they previously referred to "English's Law of Conservation of Information" (a term they made up). English is telling you now that he did not understand their engineering papers until he read the one addressing biological evolution.
ABSTRACT: Laws of nature are universal in scope, hold with unfailing regularity, and receive support from a wide array of facts and observations. The Law of Conservation of Information (LCI) is such a law. LCI characterizes the information costs that searches incur in outperforming blind search. Searches that operate by Darwinian selection, for instance, often significantly outperform blind search. But when they do, it is because they exploit information supplied by a fitness function — information that is unavailable to blind search. Searches that have a greater probability of success than blind search do not just magically materialize. They form by some process. According to LCI, any such search-forming process must build into the search at least as much information as the search displays in raising the probability of success. More formally, LCI states that raising the probability of success of a search by a factor of q/p (> 1) incurs an information cost of at least log(q/p). LCI shows that information is a commodity that, like money, obeys strict accounting principles. This paper proves three conservation of information theorems: a function-theoretic, a measure-theoretic, and a fitness-theoretic version. These are representative of conservation of information theorems in general. Such theorems provide the theoretical underpinnings for the Law of Conservation of Information. Though not denying Darwinian evolution or even limiting its role in the history of life, the Law of Conservation of Information shows that Darwinian evolution is inherently teleological. Moreover, it shows that this teleology can be measured in precise information-theoretic terms. [emphasis added]
You do not have to read far into the paper to find that intelligence creates information to guide biological evolution. The passage I've highlighted contradicts the Conservation Lemma (wish I hadn't called it that) I proved in my first paper (1996) regarding "no free lunch" in so-called search. The fundamental reason that there is no free lunch is that the "search" (which is nothing more than sampling, with performance measured on the sample) cannot gain exploitable information by evaluation of the fitness function. This is really just a formalization of the famous problem of induction, i.e., observations say nothing about what has yet to be observed. Use of observations to decide what to observe is a source of sampling bias, not information. Therefore, when the performance measured on a sample obtained by biased sampling is better or worse than the expected performance for uniform sampling ("blind search"), the difference can be explained only in terms of bias. I'll say much more in a forthcoming post.
You will not read all of the paper, and thus I want to call your attention to the 1-1/3 page "Conclusion: 'A Plan for Experimental Validation.'" Some highlights:
The Law of Conservation of Information, however, is not merely an accounting tool. Under its aegis, intelligent design merges theories of evolution and information, thereby wedding the natural, engineering, and mathematical sciences. On this view (and there are other views of intelligent design), its main focus becomes how evolving systems incorporate, transform, and export information. Moreover, a principal theme of its research becomes teasing apart the respective roles of internally produced and externally applied information in the performance of evolving systems.
[...]
In such information-tracking experiments, the opponent of intelligent design hopes to discover a free lunch. The proponent of intelligent design, by contrast, attempts to track down hidden information costs and thereby confirm that the Law of Conservation of Information was preserved. There is no great mystery in any of this. Nor do such experiments to confirm intelligent design merely apply to the origin of life. Insofar as evolution (whether chemical or biological) is an exact experimental science, it will exhibit certain informational properties. Are those properties more akin to alchemy, where more information comes out than was put in? Or are they more akin to accounting, where no more information comes out than was put in? A systematic attempt to resolve such questions constitutes a plan for experimentally verifying intelligent design.
All of the published "information-tracking experiments" have all been analyses of evolutionary computations. (My next post shows that the "information" is nothing but logarithmically transformed performance, and that the misinterpretation is rooted in Marks' misunderstanding of the "no free lunch" theorems.) The highlighted passage indicates how Dembski and Marks will argue, perhaps as expert witnesses in the next judicial test of public-school instruction in "intelligent design" creationism (Dembski was to serve as a witness in the last, but withdrew), that their engineering/computing publications support the claim that biological evolution requires intelligent guidance.
This is in no way a suggestion that you respond to anything but the technical (de)merits of their work. Dembski himself referred a New York Times science reporter to me as a fair-minded critic of ID creationism. I have also protested what I considered to be an infringement of Marks' academic freedom at Baylor University. My intent here is to impress on you how important it is to do a thorough review, and to insist that the authors make clear to you everything that they are doing. In particular, require that they provide a rigorous definition of "search," rather than give examples or suggest that everyone knows what the term means. If the definition does not make "search" out to be sampling, with performance measured on the sample (as in Wolpert and Macready [1997], "No Free Lunch Theorems for Optimization"), then you should ask why it does not.
Monday, April 2, 2012
Raising an eyebrow at a Springer series editor
Springer announced last month that it would publish Biological Information: New Perspectives, the proceedings of a more-or-less secret conference of creationists. The publisher retracted the announcement almost immediately, saying that it was automatically generated, and that the volume was undergoing additional review.
Biological Information was listed, oddly enough, in an engineering series, the "Intelligent Systems Reference Library." The creationist argument that life was engineered is not engineering, of course. The creationists themselves regard it as science.* Only one of the editors of the proceedings, Bob Marks, has worked in the field of intelligent systems. It was probably he who proposed the volume to Springer.
I happened upon a volume in the series, and had a look at its two editors and 43 titles, 35 of which are dated 2011 or 2012. Seeing that one of the series editors is Janusz Kacprzyk, I thought immediately of the Polish journal that announced a forthcoming article by Marks and Dembski (another of the proceedings editors), but suspended operations prior to publishing it. And Prof. Kacprzyk was indeed on the editorial board of the International Journal of Information Technology and Intelligent Computing.
Membership on an editorial board is more an honor than anything else, and it's doubtful that Prof. Kacprzyk was involved in the process of review and acceptance of the article. However, it's not unreasonable to ask what he knew about it. And I did, with no mention whatsoever of Springer:
I'm curious as to how much you knew about the article. Were you aware that many scientists and engineers objected to it as "intelligent design" creationism? Did you read the article?
Prof. Kacprzyk did not dignify my email with a response. So I'll dignify his non-response with a raised eyebrow. If he knew nothing about the article, then why not say so?
How, precisely, do the editors of a series on engineered intelligent systems receive a proposal for a volume on biological information, and conclude other than that it's outside the scope of the series? The parsimonious guess is that they're compensated on a per-volume basis, and care more about cranking out volumes than anything else. But inquiring minds want to know.
* I say that ID creationism falls into the category of speculative philosophy, "which makes claims that cannot be verified by everyday experience of the physical world or by a scientific method." And rather than advocate censorship of Biological Information, I call for Springer to classify it correctly.
The central theme of the volume is, I suspect, that biological information is the consequence of non-material intelligence operating on matter. This is a teleological view of physical reality. What's new about it is the tacit claim that something unobservable (intelligence) creates measurable stuff (information) out of nothing with evident purpose. It is hardly unfair to characterize this as speculative philosophy seeking to become science.
In the Library of Congress classification system, BD493-701 is associated with "teleology, space and time, structure of matter, plurality of worlds." Books in this range have a great deal to say about science, but are not themselves works of science. I believe that Biological Information belongs with them. Irrespective of how libraries classify it, I hope that Springer will go on record with a statement that the volume is meta-scientific.
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https://educatingphysics.com/a-level/module-4-electrons-waves-and-photons/electricity-charge-and-current/5-the-current-equation/
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Objectives:
• To state what is meant by the term mean drift velocity of charge carriers;
• To be able to select and use the equation $I = Anev$;
• To describe the difference between conductors, semiconductors and insulators in terms of the number density n.
Mean Drift Velocity
In order for a current to flow in a wire the charge carriers, i.e. electrons, must be moving. How fast they are moving depends on several factors, some of which include the potential difference across the wire, the resistance of the wire and the number of electrons present.
When there is no potential difference across a particular wire, each individual charge carrier (in most cases electrons) will be moving in its own direction with a speed dependent on the amount of energy it has previously gained; this energy could depend on the thermal energy it has gained from its surroundings. So a circuit like the following; with a wire, as located in the circuit, will have electrons in it which are moving with their own internal energy;
When a potential difference (voltage) is supplied across the end of a wire, each electron is forced to move in a certain direction. The potential difference forces the electrons along – work is done on the charged particles;
Here we will be discussing how fast the electrons need to be travelling in order to produce an ‘adequate’ current. Since $I = \frac{\Delta Q}{\Delta t}$; a current can only flow if the charges move some distance in a time t seconds.
Deriving the current equation
For this derivation we will be making the assumption that all the electrons will be travelling at the same speed, this speed will actually be the average speed, or mean drift velocity, of the electrons.
If a detector is placed at position and is capable of timing a single charge flowing past this point;
Suppose over a time $t$ second, the highlighted electron will travel a distance $l$.
Assuming all the electrons are travelling at the same speed, all the electrons in the cylinder of length $l$ will have in fact flowed past the detector;
In order to work out how much current has flowed, we first need to work out how much charge has passed the detector. The total amount of charge that will have passed the detector would fill the volume, and this volume can be calculated;
Volume of the cylinder, $V = l \times A$, where $A$ is the cross sectional area of the wire.
This cylinder will not be entirely made up of electrons, there will be ions for example as well, however for a specific material there will be a certain concentration of electrons per metre cubed $n$.
The number of electrons in this cylinder can then be written as;
$number\ of\ electrons\ in\ cylinder = n \times A \times l$
If each electron carries a charge $q$ then;
The charge charge by the cylinder, $Q = n \times A \times l \times q$
Since this cylinder is dependent on how long the detector is timing for, an element of time should be in the equation for the $Q$. If all the electrons are travelling at a mean drift velocity $v$ for a time $t$ seconds, and $v = \frac{l}{t}$ we can write $l = v \times t$
therefore; $Q = n \times A \times v \times t \times q$
since $I = \frac{Q}{t}$
we can write; $I = \frac{Q}{t} = \frac{n \times A \times v \times t \times q}{t}$
The $t$‘s on the right hand side of this equation cancel to give:
$I = n \times A \times v \times q$
Since the charge of an electron, in this case $q$, is $1.6 \times 10^{-19}$ or also denoted with an $e$, we can write;
$I = n \times A \times v \times e$
$I = nAve$
where;
$I$ is the current, measured in $A$
$n$ is the number of electrons per metre cubed, therefore measured in $m^{-3}$
$A$ is the cross sectional area, measured in $m^{2}$
$v$ is the mean drift velocity of the electrons, measured in $ms^{-1}$
$e$ is the charge of an electron, $1.6 \times 10^{-19}$, measure in $C$
One method of checking whether this equation is valid is to check the units are conserved on each side;
$I = nAve$
$A = m^{-3} \times m^{2} \times ms^{-1} \times C$
$A = s^{-1} \times C$ Since, $I = \frac{Q}{t}$ and therefore $A = \frac {C}{s}$, the equation holds true.
So, to address the original question how fast do electrons need to be travelling in order to produce an ‘adequate’ current?
Lets plug in some realistic numbers to determine the mean drift velocity:
If a current of $0.50 \ A$ flows through a copper wire measured to be $0.2019 \ mm$ in thickness, using a micrometer, and copper has $8.5 \times 10^{28}$ electrons per metre cubed:
$I = 0.50 \ A$
$n = 8.5 \times 10^{28} \ m^{-3}$
$d = 0.2019 \ mm = 0.2019 \times 10^{-3} \ m$
A ‘non-deformed’ wire can be assumed to be cylindrical and therefore the cross sectional area can be said to be circular. So $A = \pi r^{2}$
$A = \pi (\frac{d}{2})^{2} = \pi (\frac{0.2019 \times 10^{-3}}{2})^{2} = 3.202 \times 10^{-8} m^{2}$
Rearranging $I = nAve$ to give $v = \frac{I}{nAe}$ and substituting everything in gives:
$v = \frac{0.50}{8.5 \times 10^{28} \times 3.202 \times 10^{-8} \times 1.6 \times 10^{-19}}$
$v = \frac{0.50}{435.47}$
$v = 1.148 \times 10^{-3}$
$v = 1.1 \times 10^{-3} ms^{-1} \ ({2s.f})$
This shows that the mean drift velocity of electrons flowing down a standard gauge wire with a current of $0.50 \ A$ is very slow, approximately $1 mms^{-1}$. Many people think that electrons travel down wires extremely quickly, which would explain why a light bulb would turn on almost immediately after a switch has been flicked). However, they actually travel very slowly and the reason a bulb still turns on as if instantaneously is because all electrons repel one another, as soon as one electrons is propelled along by a power source it repels its neighbouring electrons, which does the same to its neighbouring electrons, and so on and so forth until the bulb (this repulsive force os what causes a light bulb to light up so quickly.
Electrons as incredibly small, they have a mass of $9.11 \times 10^{-31} kg$, they are not visible to any human instrument (they can only be detected so far), so the fact that they can travel even $1 mm$ in just one second is actually quite impressive.
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https://math.stackexchange.com/questions/1689013/the-fundamental-theorem-of-symmetric-polynomials
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# The Fundamental Theorem of Symmetric Polynomials
This theorem stays that any symmetric polynomial can be expressed as a polynomial of elementary polynomials. So let's suppose I have a symmetric polynomial $f(x_1,x_2,...,x_n)$ in $R[\mathbb{X}]$. I can find a unique polynomial $g(s_1,s_2,...,s_n)$ in $R[\mathbb{X}]$ so I can express f in term of g, where $s_1,s_2,...,s_n$ are elementary polynomials. My question to you is: Is there a algorithm/set of stepts to determine g? Thanks.
Let $c x_1^{a_1} x_2^{a_2} \dots x_n^{a_n}$ be the lexicographically largest monomial of $f$, that is there are no monomials with strictly larger exponent of $x_1$, and no monomials with $x_1$ exponent ${a_1}$ that have a higher power of $x_2$, and so on. We'll think of this as being the leading term of the polynomial.
Now the key thing to notice is that $e_n^{a_n}e_{n-1}^{(a_{n-1}-{a_n})} \dots e_1^{(a_1-a_2)}$ contains the monomial $x_1^{a_1} x_2^{a_2} \dots x_n^{a_n}$ with coefficient $1$ and all other monomials it contains are smaller lexicographically.
Now the point is you can consider the leading term of $f - c e_n^{a_n}e_{n-1}^{(a_{n-1}-{a_n})} \dots e_1^{(a_1-a_2)}$, and so on. Each step reduces the leading term (in lexicographic order), so this process must eventually terminate, at which point you have written $f$ in terms of the elementary symmetric functions.
• Ok, you kinda lost me at the last paragraph. Can you please show me how this work on a example. Let's say I have the following polynomial: $$P(x_1,x_2,x_3) = x_1^4+x_2^4+x_3^4-2x_1^2x_2^2-2x_2^2x_3^2-2x_1^2x_3^2$$. Thanks a lot for your help. – Raducu Mihai Mar 9 '16 at 22:35
• The lexicographically largest term is $x_1^4$. So according to the algorithm described you should subtract off $e_1^4 = (x_1+x_2+x_3)^4$. The point being that what remains, while having more terms, will have a smaller leading term namely $-4x_1^3x_2$. Then we apply the same operation again to this polynomial $P - e_1^4$, this time adding $4e_2e_1^2$ to cancel the leading term. Next we would cancel the leading term $P - e_1^4 + 4e_2e_1^2$, and so on. Eventually we are left with $P - g(e_1,e_2,e_3)$ having no leading term and hence $P - g(e_1,e_2,e_3) = 0$ as desired. – Nate Mar 10 '16 at 15:14
You can use divided difference operators to express the polynomial in terms of Schur polynomials, then you can apply the second Jacobi-Trudi formula, which expresses a Schur polynomial as the determinant of a matrix whose entries are elementary symmetric polynomials. Computationally this is rather inefficient, but it is nonrecursive, which is sometimes advantageous.
• Hey, thank you for your answare. Can you please show me how this would work on a real example. See the polynomial in the comment section for @Nate 's answare. – Raducu Mihai Mar 10 '16 at 15:10
• @Raducu I don't have a computer algebra system here, but my hand calculations resulted in $\partial^{4123}(p)=3$, $\partial^{5423}(p)=-1$, $\partial^{3423}(p)=-2$, so $p=3s_{(31)}-s_{(211)}-2s_{(22)}$, and you can go to the Wikipedia article on the Jacobi-Trudi formula and substitute what it gives you. – Matt Samuel Mar 10 '16 at 16:34
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http://math.stackexchange.com/questions/160626/prove-that-g-abelian-if-g-pq2
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# Prove that $G$ abelian if $|G|= pq^2$.
Let $G$ be a group of order $pq^2$, where $p \neq q$ prime and $p$ does not divide $| Aut (G) |$. Show that $G$ is abelian.
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If this is homework, have you at least tried something? Can you show some work? Note that this is proved in some algebra books exercises ; I know that in Dummit & Foote's Abstract Algebra, there's a sketch of proof in the exercises. – Patrick Da Silva Jun 20 '12 at 4:40
It would be nice if you didn't phrase your question as a command, if you told us what you know about the problem, what theorems you are aware of that might be relevant, what work you have put into it yourself, etc., etc., etc. – Gerry Myerson Jun 20 '12 at 4:40
Isn't it important to know that $p$>$q$ or $q$>$p$ in this problem? – Babak S. Jun 20 '12 at 6:23
Firstly,we can consider a homomorphism $f:G\rightarrow Aut(G)$ such that: $f(x)=t_x$,where $t_x:G\rightarrow G$ is defined by $t_x(g)=xgx^{-1}$.
Note that $ker f=Z(G)$,then by first isomorphism theorm, we get: $G/Z(G)\cong f(G) \le Aut(G)$.So $|G|$can be divided by $|Z(G)||Aut(G)|$.
Hence, $Z(G)$ is divided by $p$.By Cauchy Theorem,$Z(G)$ contains a element of order $p$. We find that the cyclic subgroup generated by that element is of order $p$ and hence is Sylow $p$ subgroup and since it is in the center, we can conclude that it is the unique Sylow $p$ subgroup,which is also normal.
Let $Q$ be a Sylow $q$ subgroup in $G$.Since $p$ and $q$ are relative prime,we have $P\cap Q=\{1\}$.Besides, $PQ$ is a subgroup of order $pq^2$ since $P$ is normal and $|PQ|=|P||Q|/|P\cap Q|$.We have $PQ=G$.
Now, we only focus on $Q$.From class equation ,we get that $Z(Q)$ is nontrivial.If $Z(Q)$ is of order $q^2$,then $Q$ commutes with its elements, otherwise $|Z(Q)|=q$. In this case,$Q/Z(Q)$ which is of order $q$ and hence is cyclic, so $Q$ is abelian. In both case, $Q$ always commutes with its elements.
Since $G=PQ$,$P$ is contained in the centre and $Q$ commutes with its elements,we can conclude that $G$ is abelian.
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I don't have that reference noted by Patrick, but I think you can use the following hint.
Hint: Use the fact that $|\frac{G}{Z(G)}|$ divides the order of $Aut(G)$.
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So $|G/Z(G)|$ is not divisible by p which implies $|Z(G)|$ is $p, pq$ or $pq^2$, the case $Z(G)=pq$ is ruled out as otherwise $G/Z(G)$ is cyclic and thus $Z(G)=G$. It remains to rule out the case $Z(G)=p$ ? – user31899 Jun 20 '12 at 8:29
@user31899: If $Z(G)=p$ then $G≅Z(G)×\mathbb Z_{q^2}$? – Babak S. Jun 20 '12 at 8:39
Good work, nice hint! +1 – amWhy Mar 6 '13 at 0:58
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http://electronics.stackexchange.com/questions/110152/anybody-know-what-this-db25-jumper-connection-is-called
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# Anybody know what this DB25 jumper connection is called?
I'm in the process of motorizing a few electronics project. Been racking my brains with Google and Mouser trying to identify the following part that is connected to a DB25 connector.
It looks like some kind of board with header pins, but as I am an electronics novice have no idea what this is called. Using jumper wires seems like a nicer semi-permanent solution than a breakout box.
Here's the suspect:
Any help on this is appreciated!
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An alternative might be to search for a wire-wrap version of the DB25 connector; this will have suitably long 0.64mm square pins - IF they are still made... – Brian Drummond May 12 at 17:27
Do the pins go through the board? If so it sort of looks like right angle wire wrap parts, with an extra plastic molding like a set of header pins and a PCB added, perhaps for strength. But if the PCB is joining distinct pins, then it's just an ordinary through hole right angle DB25 and a through hole header. – Chris Stratton May 12 at 17:42
I've just looked up DB25 breakout board. A number of parts similar to the O.P. photo came up. – Nick Alexeev May 12 at 18:13
Judging by the "brokenish" pin at the bottom, I would say it is much like the conclusion by Chris. The breakout's are all about $15-$20, so will probably try and rig this myself. – frischky May 12 at 18:26
It looks like this is a normal board-mount DB-25 mounted to a unusually small board. The only other pard on the board seems to be a header, which is what the jumper wires are connecting to.
This was probably done because the jumper wires you can easily get like that will be for .1" pitch, and the pins on the DB connector are a little off from that. Also, the DB pins don't stick out very far on normal thru hole parts.
The part that isn't clear from the picture is whether either connector was thru hole or surface mount. If the header was thru hole, you'd expect the pins to stick out the other side of the board a bit, but there doesn't seem to be space for that. On the other hand, from what little we can see in the picture, there don't appear to be SMD pads.
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Actually, the pin spacing for Dsubs is .109 inch. – WhatRoughBeast May 12 at 18:17
@What: I have update my answer accordingly. – Olin Lathrop May 12 at 19:45
It looks like one of these: -
And somebody has designed a little circuit board that solders to the pins and brings the connections out to a single 0.1" header. The header has a mating half fitted as per your picture.
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https://www.aimsciences.org/article/doi/10.3934/mcrf.2015.5.613
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# American Institute of Mathematical Sciences
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September 2015, 5(3): 613-649. doi: 10.3934/mcrf.2015.5.613
## Optimal control problems of forward-backward stochastic Volterra integral equations
1 Institute for Financial Studies and School of Mathematics, Shandong University, Jinan, Shandong 250100 2 School of Mathematics, Sichuan University, Chengdu 610065, China 3 Department of Mathematics, University of Central Florida, Orlando, FL 32816
Received April 2014 Revised March 2015 Published July 2015
Optimal control problems of forward-backward stochastic Volterra integral equations (FBSVIEs, in short) are formulated and studied. A general duality principle is established for linear backward stochastic integral equation and linear stochastic Fredholm-Volterra integral equation with mean-field. With the help of such a duality principle, together with some other new delicate and subtle skills, Pontryagin type maximum principles are proved for two optimal control problems of FBSVIEs.
Citation: Yufeng Shi, Tianxiao Wang, Jiongmin Yong. Optimal control problems of forward-backward stochastic Volterra integral equations. Mathematical Control & Related Fields, 2015, 5 (3) : 613-649. doi: 10.3934/mcrf.2015.5.613
##### References:
[1] G. Ainslie, Picoeconomics: The Strategic Interaction of Successive Motivational States within the Person,, Cambridge Univ. Press 1992., (1992). Google Scholar [2] D. Duffie and L. G. Epstein, Stochastic differential utility,, Econometrica, 60 (1992), 353. doi: 10.2307/2951600. Google Scholar [3] D. Duffie and C. F. Huang, Stochastic Production-Exchange Equilibria,, Reserach paper No.974, (1986). Google Scholar [4] M. I. Kamien and E. Muller, Optimal control with integral state equations,, Rev. Econ. Stud., 43 (1976), 469. doi: 10.2307/2297225. Google Scholar [5] I. Karatzas and S. E. Shreve, Brownian Motion and Stochastic Calculus,, Springer, (1988). doi: 10.1007/978-1-4684-0302-2_2. Google Scholar [6] J. Lin, Adapted solution of backward stochastic nonlinear Volterra integral equation,, Stoch. Anal. Appl., 20 (2002), 165. doi: 10.1081/SAP-120002426. Google Scholar [7] J. Ma and J. Yong, Forward-Backward Stochastic Differential Equations and Their Applications,, Springer-Verlag, (1999). Google Scholar [8] E. Pardoux and P. Protter, Stochastic Volterra equations with anticipating coefficients,, Ann. Probab., 18 (1990), 1635. doi: 10.1214/aop/1176990638. Google Scholar [9] S. Peng, A general stochastic maximum principle for optimal control problems,, SIAM J. Control Optim., 28 (1990), 966. doi: 10.1137/0328054. Google Scholar [10] S. Peng, Backward stochastic differential equations and application to optimal control,, Appl. Math. Optim., 27 (1993), 125. doi: 10.1007/BF01195978. Google Scholar [11] Y. Shi and T. Wang, Solvability of general backward stochastic Volterra integral equations,, J. Korean Math. Soc., 49 (2012), 1301. doi: 10.4134/JKMS.2012.49.6.1301. Google Scholar [12] Y. Shi, T. Wang and J. Yong, Mean-field backward stochastic Volterra integral equations,, Discrete. Contin. Dyn. Syst. Ser. B, 18 (2013), 1929. doi: 10.3934/dcdsb.2013.18.1929. Google Scholar [13] T. Wang and Y. Shi, Symmetrical solutions of backward stochastic Volterra integral equations and applications,, Discrete Contin. Dyn. Syst. Ser. B., 14 (2010), 251. doi: 10.3934/dcdsb.2010.14.251. Google Scholar [14] T. Wang and J. Yong, Comparison theorems for backward stochastic Volterra integral equations,, Stoch. Process Appl., 125 (2015), 1756. doi: 10.1016/j.spa.2014.11.013. Google Scholar [15] Z. Wang and X. Zhang, Non-Lipschitz backward stochastic volterra type equations with jumps,, Stoch. Dyn., 7 (2007), 479. doi: 10.1142/S0219493707002128. Google Scholar [16] J. Yong, Backward stochastic Volterra integral equations and some related problems,, Stoch. Process Appl., 116 (2006), 779. doi: 10.1016/j.spa.2006.01.005. Google Scholar [17] J. Yong, Continuous-time dynamic risk measures by backward stochastic Volterra integral equations,, Appl. Anal., 86 (2007), 1429. doi: 10.1080/00036810701697328. Google Scholar [18] J. Yong, Well-posedness and regularity of backward stochastic Volterra integral equation,, Probab. Theory Relat. Fields, 142 (2008), 21. doi: 10.1007/s00440-007-0098-6. Google Scholar [19] J. Yong and X. Y. Zhou, Stochstic Control: Hamiltonian Systems and HJB Equations,, Springer-Verlag, (1999). doi: 10.1007/978-1-4612-1466-3. Google Scholar
show all references
##### References:
[1] G. Ainslie, Picoeconomics: The Strategic Interaction of Successive Motivational States within the Person,, Cambridge Univ. Press 1992., (1992). Google Scholar [2] D. Duffie and L. G. Epstein, Stochastic differential utility,, Econometrica, 60 (1992), 353. doi: 10.2307/2951600. Google Scholar [3] D. Duffie and C. F. Huang, Stochastic Production-Exchange Equilibria,, Reserach paper No.974, (1986). Google Scholar [4] M. I. Kamien and E. Muller, Optimal control with integral state equations,, Rev. Econ. Stud., 43 (1976), 469. doi: 10.2307/2297225. Google Scholar [5] I. Karatzas and S. E. Shreve, Brownian Motion and Stochastic Calculus,, Springer, (1988). doi: 10.1007/978-1-4684-0302-2_2. Google Scholar [6] J. Lin, Adapted solution of backward stochastic nonlinear Volterra integral equation,, Stoch. Anal. Appl., 20 (2002), 165. doi: 10.1081/SAP-120002426. Google Scholar [7] J. Ma and J. Yong, Forward-Backward Stochastic Differential Equations and Their Applications,, Springer-Verlag, (1999). Google Scholar [8] E. Pardoux and P. Protter, Stochastic Volterra equations with anticipating coefficients,, Ann. Probab., 18 (1990), 1635. doi: 10.1214/aop/1176990638. Google Scholar [9] S. Peng, A general stochastic maximum principle for optimal control problems,, SIAM J. Control Optim., 28 (1990), 966. doi: 10.1137/0328054. Google Scholar [10] S. Peng, Backward stochastic differential equations and application to optimal control,, Appl. Math. Optim., 27 (1993), 125. doi: 10.1007/BF01195978. Google Scholar [11] Y. Shi and T. Wang, Solvability of general backward stochastic Volterra integral equations,, J. Korean Math. Soc., 49 (2012), 1301. doi: 10.4134/JKMS.2012.49.6.1301. Google Scholar [12] Y. Shi, T. Wang and J. Yong, Mean-field backward stochastic Volterra integral equations,, Discrete. Contin. Dyn. Syst. Ser. B, 18 (2013), 1929. doi: 10.3934/dcdsb.2013.18.1929. Google Scholar [13] T. Wang and Y. Shi, Symmetrical solutions of backward stochastic Volterra integral equations and applications,, Discrete Contin. Dyn. Syst. Ser. B., 14 (2010), 251. doi: 10.3934/dcdsb.2010.14.251. Google Scholar [14] T. Wang and J. Yong, Comparison theorems for backward stochastic Volterra integral equations,, Stoch. Process Appl., 125 (2015), 1756. doi: 10.1016/j.spa.2014.11.013. Google Scholar [15] Z. Wang and X. Zhang, Non-Lipschitz backward stochastic volterra type equations with jumps,, Stoch. Dyn., 7 (2007), 479. doi: 10.1142/S0219493707002128. Google Scholar [16] J. Yong, Backward stochastic Volterra integral equations and some related problems,, Stoch. Process Appl., 116 (2006), 779. doi: 10.1016/j.spa.2006.01.005. Google Scholar [17] J. Yong, Continuous-time dynamic risk measures by backward stochastic Volterra integral equations,, Appl. Anal., 86 (2007), 1429. doi: 10.1080/00036810701697328. Google Scholar [18] J. Yong, Well-posedness and regularity of backward stochastic Volterra integral equation,, Probab. Theory Relat. Fields, 142 (2008), 21. doi: 10.1007/s00440-007-0098-6. Google Scholar [19] J. Yong and X. Y. Zhou, Stochstic Control: Hamiltonian Systems and HJB Equations,, Springer-Verlag, (1999). doi: 10.1007/978-1-4612-1466-3. Google Scholar
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http://math.stackexchange.com/questions/92190/formula-of-sum-the-nimbers?answertab=oldest
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# formula of sum the nimbers
If have well-known formula $(n + 1) n / 2 = 1 + 2 +\cdots+ n$. If the difference between the closest numbers smaller, will obtain, for example $(n + 0,1) n / (2 \cdot 0,1) = 0,1 + 0,2 +\cdots+ n$. Now if the difference between the closest numbers the smallest possible, will obtain $(n + 0,0\ldots1) n / (2 \cdot 0,0\ldots 1) = 0,0\ldots1 + 0,0\ldots2 + \ldots + n$, so can conclude $n ^ 2 / 2 = (0,0\ldots1 + 0,0\ldots2 + \cdots + n) / 0,0\ldots1$ whether conclude is correct?
EDITED VERSION:
If have well-known formula $\frac{(n + 1)n}2 = 1 + 2 +\dots+ n$.
If the difference between the closest numbers smaller, will obtain, for example $\frac{(n + 0,1) n}{2.0,1} = 0,1 + 0,2 +\dots + n$.
Now if the difference between the closest numbers the smallest possible, will obtain $\frac{(n + 0,0\dots1) n}{2 . 0,0\dots 1} = 0,0\dots 1 + 0,0\dots 2 + \dots + n$ , so can conclude $\frac{n ^ 2}2 = \frac{0,0\dots1 + 0,0\dots2 + \dots + n}{0,0\dots1}$ whether conclude is correct?
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By comma symbol, you mean decimal point? – user18325 Dec 17 '11 at 7:40
@ZeeshanMahmud Comma is used as decimal separator in many countries. – Martin Sleziak Dec 17 '11 at 7:48
Marko: I guess both these account belong to you: math.stackexchange.com/users/20189/marko and math.stackexchange.com/users/21380/marko; Maybe it would be good for you to register, so that you can better follow all questions you posted. (After you do it, you can even ask moderators to merge you account with the older unregistered ones.) – Martin Sleziak Dec 17 '11 at 7:52
shiver me nimbers – jspecter Dec 17 '11 at 8:00
Marko: I've tried to edit your question using TeX for better readability. (And maybe some other users will improve it a little more.) You should check whether I did not change the meaning of your question, unintentionally. If you're satisfied with the edited version, you can remove the original one. – Martin Sleziak Dec 17 '11 at 8:07
If we denote $k=n/\alpha$ then we get $$\sum\limits_{i=1}^k i\alpha=\frac{k(k+1)}2 \alpha = \frac{k\alpha(k\alpha+\alpha)}{2\alpha} = \frac{n(n+\alpha)}{2\alpha}.$$ For $\alpha$ of the form $10^{-s}$, i.e. $0,00\dots01$, this is precisely the first part of your question.
I am not sure I understand what you mean by the last part of your question, but if you want to say that $\sum\limits_{i=1}^k i\alpha=\frac{k(k+1)}2$ is approximately $\frac{n^2}{2\alpha}$, in some sense it is true, since the error is: $$\frac{n(n+\alpha)}{2\alpha} - \frac{n^2}{2\alpha} = \frac {n\alpha}{2\alpha}=\frac n2,$$ so the error has smaller order than the sum. (The error is $o(n^2)$, if you're familiar with this notation.)
If you know something about Riemann integral, you may notice that the sum $$\alpha \sum\limits_{i=1}^k i\alpha$$ is in fact upper Riemann sum for the function $f(x)=x$ on the interval $[0,n]$ (and for uniform partition of this interval). To see this just notice that the lengths of the intervals of partitions is $\alpha$ and the value at the end of the interval $[(i-1)\alpha,i\alpha]$ is $i\alpha$.
So it is expected that this sum is approximately $\frac{n^2}2$ for small values of $\alpha$. Your sum is $\alpha$-times smaller.
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# Targeted therapy in patients with PIK3CA-related overgrowth syndrome
### Subjects
An Author Correction to this article was published on 03 April 2019
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## Abstract
CLOVES syndrome (congenital lipomatous overgrowth, vascular malformations, epidermal naevi, scoliosis/skeletal and spinal syndrome) is a genetic disorder that results from somatic, mosaic gain-of-function mutations of the PIK3CA gene, and belongs to the spectrum of PIK3CA-related overgrowth syndromes (PROS). This rare condition has no specific treatment and a poor survival rate. Here, we describe a postnatal mouse model of PROS/CLOVES that partially recapitulates the human disease, and demonstrate the efficacy of BYL719, an inhibitor of PIK3CA, in preventing and improving organ dysfunction. On the basis of these results, we used BYL719 to treat nineteen patients with PROS. The drug improved the disease symptoms in all patients. Previously intractable vascular tumours became smaller, congestive heart failure was improved, hemihypertrophy was reduced, and scoliosis was attenuated. The treatment was not associated with any substantial side effects. In conclusion, this study provides the first direct evidence supporting PIK3CA inhibition as a promising therapeutic strategy in patients with PROS.
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### Extended Data Fig. 8 CT scan evaluation of the tumours and adipose tissue before and after BYL719 introduction.
a, Body weight evolution of PIK3CAWT and PIK3CACAGG-CreER mice treated with vehicle or BYL719 (n = 3 mice per group). b, CT scan evaluation and quantification of the fat tissue content in PIK3CAWT and PIK3CACAGG-CreER mice treated with vehicle or BYL719. Subcutaneous and visceral fat content were measured before treatment and 7 and 14 days after onset of treatment with vehicle or BYL719 (n = 3 mice per group). c, CT scan evaluation and quantification of tumour volume in PIK3CACAGG-CreER mice before and after two weeks of BYL719 treatment (arrows) (n = 3 mice per group). All data are shown as mean ± s.e.m.
### Extended Data Fig. 9 Effect of rapamycin treatment on the different PIK3CACAGG-CreER mouse models.
a, Kaplan–Meier survival curves of PIK3CACAGG-CreER mice that received a single dose of 40 mg kg−1 tamoxifen and were treated with or without rapamycin after tamoxifen administration. b, Representative pictures of the liver of PIK3CACAGG-CreER mice treated with rapamycin 40 days after Cre induction. c, Morphology of livers and spleens from PIK3CAWT and PIK3CACAGG-CreER mice that were treated with or without rapamycin after Cre induction. Scale bars, 10 μm. d, Western blot and quantification of P-AKT (Ser473) and P-S6RP in the liver, heart and muscle, respectively, of PIK3CAWT and PIK3CACAGG-CreER mice treated with vehicle or rapamycin directly after Cre induction. e, PIK3CACAGG-CreER mice were treated with rapamycin one month after Cre induction with a single dose of 4 mg kg−1 tamoxifen and followed for one month. All data are shown as mean ± s.e.m. ANOVA followed by Tukey–Kramer test (two-tailed). PIK3CACAGG-CreER versus PIK3CAWT mice, ***P < 0.001. PIK3CACAGG-CreER mice treated with rapamycin compared with PIK3CACAGG-CreER mice treated with vehicle, ###P < 0.001.
### Extended Data Fig. 10 In vitro effect of BYL719 and rapamycin on fibroblasts from PIK3CACAGG-CreER mice.
a, Skin fibroblasts from PIK3CAWT and PIK3CACAGG-CreER mice were isolated and exposed to vehicle or increasing concentrations of BYL719 or rapamycin for 24 h. b, Quantification. White column, without 4-OHT; black column, with 4-OHT. All data are shown as mean ± s.e.m. ANOVA followed by Tukey–Kramer test (two-tailed). Before versus after Cre induction with 4-OHT, ***P < 0.001. BYL719 or rapamycin exposure compared with cells treated with vehicle, ##P < 0.01 and ###P < 0.001.
### Extended Data Fig. 11 Effect of BYL719 in patients with PROS.
a, Patients 10–17 before and after 180 days of BYL719 treatment. Patient 10 was a 14-year-old boy with severe asthenia, dyspnea and bilateral overgrowth of lower limbs. After 180 days of treatment asthenia resolved and we observed a marked reduction in hypertrophy of the limbs. Patient 11 was a 14-year-old boy with overgrowth of the right buttock and an intra-abdominal vascular tumour infiltrating the left kidney and spinal nerve. He had chronic haematuria and was permanently confined to bed owing to pain. After 180 days, haematuria resolved and the volume of the intraabdominal vascular malformation was reduced by up to 68%. He had no more pain and became capable of walking. Patient 12 was a 15-year-old boy with multiple large tumours of the trunk and the back. After 180 days of treatment the tumours had reduced in size. Patient 13 was a 16-year-old boy with megalencephaly-capillary malformation (MCAP) and left hemifacial hyperplasia. Treatment led to a reduction in hemifacial hypertrophy and cognitive improvement. Owing to the deformation, this patient was not able to open the left eye. After 180 days of BYL719 treatment, he was able to open the eye (not shown for confidentiality reasons). Patient 14 was a 16-year-old girl with MCAP and a chronic noninfectious palpebral cellulitis who was steroid-dependent. BYL719 treatment led to the healing of the cellulitis and steroids were stopped without a flare. We also observed enhancement of cognitive function and behaviour and improvement of scoliosis. Patient 15 was a 19-year-old man with overgrowth of the left foot and unstable and painful walking. Treatment led to an improvement in the overgrowth as well as an improvement in walking distance. Patient 16 was a 32-year-old man with overgrowth of the right foot and unstable and painful walking. Treatment led to an improvement in the overgrowth as well as an improvement in walking distance. Patient 17 was 50-year-old woman with generalized hypertrophy, and severe and diffuse pain with opioid dependency. She was permanently confined to bed. After six months of treatment we observed an improvement in tiredness, and resolution of pain, and we were able to stop opioids within two weeks. The patient became able to walk again. b, PIK3CA mutations identified in the 17 patients. c, For each patient we determined a target lesion (see Supplementary Table 2) that was clinically measured at each time point. The graph represents the changes (per cent) during the 180 days of treatment with BYL719. Each line is a single patient. d, Mean body weight changes (per cent) during the 180 days of treatment with BYL719 (n = 13 patients, patients 1–13), excluding the four obese patients (patients 14, 15, 16 and 17). e, Mean body weight loss in the four obese patients during the 180 days of treatment with BYL719. All data are shown as mean ± s.e.m.
### Extended Data Fig. 12 Height changes in children during treatment period and radiological changes with BYL719 treatment.
a, Height changes in children during the 180 days of treatment with BYL719. b, MRI scans of patient 1 before and after 180 days of BYL719 treatment. Arrows show the target lesion. c, Three-dimensional MRI-based reconstruction of the chest tumour in patient 1 before and after 180 days of BYL719 treatment. d, Examples of MRI showing the evolution of the target lesions in patients 9 and 11. e, Volume evolution of the radiological target lesion after 180 days of BYL719 treatment. f, Diffusion MRI demonstrating the enhancement of brain perfusion in patient 14 after 180 days of BYL719. g, PET scan images of patients 6, 9, 15 and 17, before and after 90 days of BYL719 treatment. The arrows delineate hypermetabolic activity before and after 90 days of treatment.
## Supplementary Information
### Supplementary Tables 1-2
Supplementary Table 1 contains the principal demographic characteristics of the patients, the clinical manifestation and the PIK3CA mutation, and Supplementary Table 2 shows the responses to treatment.
### Supplementary Figures
This file contains the uncropped blots.
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### Cite this article
Venot, Q., Blanc, T., Rabia, S.H. et al. Targeted therapy in patients with PIK3CA-related overgrowth syndrome. Nature 558, 540–546 (2018). https://doi.org/10.1038/s41586-018-0217-9
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