url
stringlengths 14
1.76k
| text
stringlengths 100
1.02M
| metadata
stringlengths 1.06k
1.1k
|
|---|---|---|
http://repository.gsi.de/collection/PhDThesis?ln=en
|
# Ph.D. Theses
2017-11-1710:17 [GSI-2017-01754] Dissertation / PhD Thesis Seegert, N. Signatures of the quantum vacuum in inhomogeneous electromagnetic fields Jena, 167 pp. (2017) = Friedrich-Schiller-Universität Jena, Dissertation, 2017 Abstract: According to the theory of quantum electrodynamics, zero-point fluctuations of the vacuum manifest themselves through the ubiquitous creation and annihilation of virtual electron-positron pairs. These give rise to classically forbidden nonlinear interactions between strong electromagnetic fields in vacuum, first described by Heisenberg and Euler in 1936 [...] External link: Fulltext 2017-11-1710:06 [GSI-2017-01752] Dissertation / PhD Thesis Marx-Glowna, B. Hochauflösende Röntgenpolarimetrie Jena, 112 pp. (2017) = Friedrich-Schiller-Universität Jena, Dissertation, 2017 Abstract: Polarimetry has a long history with versatile applications in chemistry and pharmacy in the visible spectral range. In the field of X-ray radiation, the interest in high-resolution polarimeters has only increased in recent years. [...] External link: Fulltext 2017-11-1710:01 [GSI-2017-01751] Dissertation / PhD Thesis Wu, Z. Angular Correlation and Polarization of X-rays Emitted from Highly Charged Ions Jena, 120 pp. (2017) = Friedrich-Schiller-Universität Jena, Dissertation, 2017 Abstract: In collisions of highly charged ions with electrons or light, ions are usually excited to one of their excited states and, then, may stabilize radiatively under the emission of fluorescence photons. Detailed studies on the emitted photons can help understand the structure and collision dynamics of the ions. [...] External link: Fulltext 2017-11-1709:56 [GSI-2017-01750] Dissertation / PhD Thesis Ullmann, J. Laserspektroskopie an hochgeladenen Bismutionen zum Test der Quantenelektrodynamik Jena, 128 pp. (2017) = Friedrich-Schiller-Universität Jena, Dissertation, 2017 Abstract: Ths dissertation concerns a test of the theory of quantum electrodynamics in strong fields by laser spectroscopy of the ground state hyperfine splitting of highly charged bismuth ions. The experiment was performed and analyzed at the storage ring ESR at Helmholtzzentrum für Schwerionenforschung in Darmstadt. [...] External link: Fulltext 2017-11-1310:40 [GSI-2017-01725] Dissertation / PhD Thesis Krieg, J. Characterization of individual Bi$_2$Te$_3$ nanowires electrodeposited in etched ion-track membranes for nano-ARPES and electrical transport studies. Darmstadt : Technische Universität Darmstadt, 155 p (2017) = Technische Universität Darmstadt, Dissertation, 2017 2017-10-2713:37 [GSI-2017-01703] Dissertation / PhD Thesis Durante, M. Modellierung der DNA-Schadenscluster-, Zellzyklus- und Reparaturweg-abhängigen Strahlenempfindlichkeit nach niedrig- und hoch-LET-Bestrahlung 115 p. (2017) = Technische Universität Darmstadt, Dissertation, 2017 2017-09-2216:23 [GSI-2017-01583] Dissertation / PhD Thesis Shreder, K. Impact of ionizing radiation on adipokine-induced inflammation in musculoskeletal diseases (MSD): Investigations in primary cells and MSD patients 97 p. (2017) = Technische Universität Darmstadt, Diss., 2017 2017-08-2209:49 [GSI-2017-01426] Dissertation / PhD Thesis Müllers, A. Production of antihydrogen via double charge exchange 195 Seiten (2013) = Johannes Gutenberg-Universität Mainz, Diss., 2013 2017-08-2209:46 [GSI-2017-01425] Dissertation / PhD Thesis Cardinali, M. Fast frontend electronics for high rate particle detectors 165 Seiten (2015) = Johannes Gutenberg-Universität Mainz , Diss., 2015 2017-08-2209:42 [GSI-2017-01423] Dissertation / PhD Thesis Bleile, A. Experimentelle Untersuchungen thermischer Eigenschaften schnell gepulster supraleitender Beschleunigermagnete 127 Seiten (2016) = Johannes Gutenberg-Universität Mainz , Diss., 2016
|
{"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": 0, "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": 0.6644493937492371, "perplexity": 18650.435364621055}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "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-2017-47/segments/1510934805023.14/warc/CC-MAIN-20171118190229-20171118210229-00534.warc.gz"}
|
https://www.clicktorelease.com/blog/creating-spherical-environment-mapping-shader/?WT.mc_id=13428-DEV-noupe-article4
|
# clicktorelease
Article | Posted on September 2013
# Creating a Spherical Environment Mapping shader
Topics: WebGL, GLSL, three.js, matcap
This is a legacy post, ported from the old system:
Images might be too low quality, code might be outdated, and some links might not work.
One of the most important aspects of computer-generated images is lighting. It takes a lot of calculations, setup and tweaking to get surfaces to look realistic and convincing.
Spherical reflection (or environment) mapping (SEM) is a fast way to fake the specular term of the lighting equation, and for specific cases, to fake lighting altogether. This technique has been popularised by software like Pixologic ZBrush or Luxology Modo.
## LitSphere/MatCap texture maps
SEM uses special texture maps called “lit spheres” or “matcaps”. These are essentially spherical reflection maps, but with a more diffuse colour instead of a sharp image. The sphere map contains everything that is in front of the camera, which means that the texture contains the incoming light inciding in the surface facing the camera. That’s why it doesn’t work as a perfect environment map: it doesn’t rotate with the view because it’s missing part of the information. All we can emulate is an object rotating by itself in a still light and camera setup.
The main idea of SEM is to get the UV coordinates (which are used to lookup the matCap texture) from the normal vector on the fragment instead of the original texture coordinates from the object. That can be done in the vertex shader -and let the GPU take care of the interpolation- or in the fragment shader. We'll do the per-vertex version first.
In order to understand SEM spatially, assume that surfaces looking straight into the camera (the normal vector is parallel to the camera vector) is mapped to the texel right in the middle of the matCap texture; and as the normal vector diverges from the camera vector (the angle between both vectors tends to 90º) the texel is looked up more towards the borders. Normals looking upwards (we're talking screen space so "up" is towards the physical top of the screen) are mapped to the top of the matCap texture; normals looking downwards, to the bottom. Same with left and right.
So first we need to set up two vectors, e (Eye) and n (Normal). Eye is the vector that goes from the camera (a point in space at the origin) to the fragment position. Normal is the normal in screen space. We need to convert the 3-dimensional position into a 4-dimensional vector to be able to multiply it by the matrices.
Once we have both vectors, we calculate the reflected vector.
This tutorial is based on the GLSL language to code the shader. If you're targeting a different shading language and don't have the reflect() function, you can replace it with the equivalent expression r = e - 2. * dot( n, e ) * n;
\begin{pmatrix} s \\ t \end{pmatrix} = \begin{pmatrix} {{\frac{r_x}{ (2\sqrt{r_x^2+r_y^2+(r_z+1)^2})}+\frac{1}{2}}} \\ {{\frac{r_y}{ (2\sqrt{r_x^2+r_y^2+(r_z+1)^2})}+\frac{1}{2}}} \end{pmatrix}
Then we take that vector, and apply the formula to get the UV tuple.
varying vec2 vN;
void main() {
vec4 p = vec4( position, 1. );
vec3 e = normalize( vec3( modelViewMatrix * p ) );
vec3 n = normalize( normalMatrix * normal );
vec3 r = reflect( e, n );
float m = 2. * sqrt(
pow( r.x, 2. ) +
pow( r.y, 2. ) +
pow( r.z + 1., 2. )
);
vN = r.xy / m + .5;
gl_Position = projectionMatrix * modelViewMatrix * p;
}
The fragment shader just takes the GPU-interpolated values for the UV tuple, and use it to lookup in the matCap texture. Here's the code:
uniform sampler2D tMatCap;
varying vec2 vN;
void main() {
vec3 base = texture2D( tMatCap, vN ).rgb;
gl_FragColor = vec4( base, 1. );
}
Here's the JavaScript code to create the shader material with three.js. Basically instantiate a new THREE.ShaderMaterial, specifying the vertex shader and fragment shader scripts, and a uniform that is a texture with the matCap map. Just in case, set the horizontal and vertical wrapping of the texture to clamp, so it doesn't wrap around. Here's the code:
### Creating THREE.js material
JavaScript - index.html
var material = new THREE.ShaderMaterial( {
uniforms: {
tMatCap: {
type: 't',
},
},
} );
material.uniforms.tMatCap.value.wrapS =
material.uniforms.tMatCap.value.wrapT =
THREE.ClampToEdgeWrapping;
And the material is ready to be assigned to an object!
## Assigning the material to an object
A material using SEM is very useful to highlight variations in the mesh: creases, bumps, even slow ondulations. It doesn't work that well on a cube, for instance. And does absolutely nothing on a sphere: SEM on a sphere is exactly the same as a planar projection of the matCap texture. Use a good old Torus Knot geometry to test the shader.
Also, you might be interested in Creating a disorted sphere with Perlin Noise
I don't think it's truly necessary, but maybe -depending on the model you're rendering, specially if it's too low-poly- you might need to perform the calculations per-fragment, instead of relying on the GPU-interpolated value. Here's the same vertex shader modified to use a per-fragment calculation:
varying vec3 e;
varying vec3 n;
void main() {
e = normalize( vec3( modelViewMatrix * vec4( position, 1.0 ) ) );
n = normalize( normalMatrix * normal );
gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1. );
}
Notice that we don't calculate the tuple vN and pass it in a varying, but instead pass the e (Eye) and n (Normal) values to the fragment shader. Here's the fragment shader code:
uniform sampler2D tMatCap;
varying vec3 e;
varying vec3 n;
void main() {
vec3 r = reflect( e, n );
float m = 2. * sqrt( pow( r.x, 2. ) + pow( r.y, 2. ) + pow( r.z + 1., 2. ) );
vec2 vN = r.xy / m + .5;
vec3 base = texture2D( tMatCap, vN ).rgb;
gl_FragColor = vec4( base, 1. );
}
So the reflection and vN calculation that was previously done per vertex and interpolated across the fragments is now calculated for every single fragment.
## Demo
The demo shows three different materials (Matte red, Shiny black and Skin) that can be used on three different models (Torus Knot, Blob and Suzanne). The materials are exactly the same, the only thing that changes is the matCap texture, but it shows the amazing power of the technique, making objects look completely different.
Toggle the "Enable Phong (per-pixel) shading" flag to see the difference between per-vertex and per-fragment calculations. The most notable difference is on the edges of the objects.
Torus Knot is a THREE.TorusKnotGeometry from the default set of geometries of three.js. Blob is a THREE.IcosahedronGeometry with the vertices disturbed based on a Perlin noise function (a mix of standard noise and crinkly noise). Suzanne is the ubiquous Blender mascot, processed with THREE.SubdivisionModifier to get a smoother model.
It works on Chrome, Firefox, Safari for OSX, Windows and Linux. It also works on Chrome and Firefox for Android. Try it on a mobile phone, it's got touch events support!
## Conclusion
That's basically it, as you can see there is nothing terribly mysterious about SEM. The secret is in using good models and good matCap maps. Google image search, a good image editing softare or -even better- a good graphician are the best tools!
Further things to try with this technique: creating the matCap texture on a previous step with a shader; combining several maps to simulate influence from different light sources; or trying to do the same but using the matCap as normal map, and see what happens.
|
{"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": 0.33620575070381165, "perplexity": 4264.86879649569}, "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-2022-33/segments/1659882572408.31/warc/CC-MAIN-20220816151008-20220816181008-00643.warc.gz"}
|
https://fjp.at/pppucpp/
|
# Programming Principles and Practice using C++
## Introduction
.. Programming Principles and Practice using C++ documentation master file, created by sphinx-quickstart on Tue Aug 6 20:13:45 2019. You can adapt this file completely to your liking, but it should at least contain the root toctree directive.
# Welcome to the walkthrough of Programming Principles and Practice using C++
..
.. toctree:: :maxdepth: 5 :caption: Contents:
ch1-computers_people_and_programming.rst
ch2-hello_world.rst
ch3-objects_types_and_values.rst
ch4-computation.rst
ch5-errors.rst
# Indices and tables
• :ref:genindex
• :ref:modindex
• :ref:search
# Chapter 1 - Computers People and Programming
.. toctree:: :maxdepth: 5 :caption: Contents:
.. mdinclude:: ../ch1-computers_people_and_programming/ch1-review.md
.. mdinclude:: ../ch1-computers_people_and_programming/ch1-terms.md
.. mdinclude:: ../ch1-computers_people_and_programming/ch1-exercises.md
Tags:
Categories:
|
{"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": 0.30391401052474976, "perplexity": 29709.9681192011}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "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-2020-40/segments/1600400191160.14/warc/CC-MAIN-20200919075646-20200919105646-00027.warc.gz"}
|
https://nyuscholars.nyu.edu/en/publications/on-maxwell-stress-and-its-relationship-with-the-dielectric-consta
|
# On Maxwell stress and its relationship with the dielectric constant in the actuation of ionic polymer metal composites
Alain Boldini, Maurizio Porfiri
Research output: Contribution to journalArticlepeer-review
## Abstract
Ionic polymer metal composites (IPMCs) are unique electroactive polymers that show promise as actuators in soft robotics and biomedical applications. The modeling and numerical simulation of the behavior of these materials are significantly complicated by the nature of the underlying electrochemical phenomena, which occur in nanometer-thick layers in the proximity of the electrodes. Hence, the dielectric constant of IPMCs is often rescaled to help numerically resolve the electric double layers. However, the effect of such a rescaling on IPMC actuation has never been systematically assessed. Motivated by recent efforts on the effect of the rescaling on Maxwell stress, we put forward a physically based analysis of the role of dielectric constant on IPMC actuation. We demonstrate that an increase of the dielectric constant decreases the magnitude of the electric field during actuation, due to the widening of the electric double layers. The decrease in the electric field intensity perfectly balances the increase of the dielectric constant scaling Maxwell stress, such that Maxwell stress is independent of the IPMC dielectric constant. The bending moment generated by Maxwell stress increases with the dielectric constant, since the thickness of the electric double layers where Maxwell stress is relevant is larger. However, the same scaling is common to all the bending moments associated with the electrochemistry, so that the relative importance of each term on IPMC actuation does not depend on the dielectric constant. This study contributes an important analysis that can support feasible and faithful numerical implementations of theories on IPMC mechanics and electrochemistry.
Original language English (US) 104875 Journal of the Mechanics and Physics of Solids 164 https://doi.org/10.1016/j.jmps.2022.104875 Published - Jul 2022
## Keywords
• Actuators
• Electroactive polymers
• Electrochemistry
• Electrolytes
• Maxwell Stress
## ASJC Scopus subject areas
• Condensed Matter Physics
• Mechanics of Materials
• Mechanical Engineering
## Fingerprint
Dive into the research topics of 'On Maxwell stress and its relationship with the dielectric constant in the actuation of ionic polymer metal composites'. Together they form a unique fingerprint.
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9004300832748413, "perplexity": 1914.098913310415}, "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-2022-49/segments/1669446711368.1/warc/CC-MAIN-20221208215156-20221209005156-00362.warc.gz"}
|
https://worldwidescience.org/topicpages/p/plasma-polymerized+4-vinyl+pyridine.html
|
#### Sample records for plasma-polymerized 4-vinyl pyridine
1. Characterization of plasma-polymerized 4-vinyl pyridine with silver nanoparticies on poly(ethylene terephthalate) film for anti-microbial properties
DEFF Research Database (Denmark)
Jiang, J.; Winther-Jensen, Bjørn; Kjær, Erik Michael
2006-01-01
scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Different thicknesses Of poly(4-vinyl pyridine) coating under different plasma polymerization conditions were studied. Silver nanoparticles with diameter around 50nm deposit were precipitated...... on the poly(4-vinyl pyridine) coating by UV irradiation in Silver nitride water solution, in order to enhance the anti-microbial properties. Different kinds of modified PET films were tested for anti-microbial properties against yeast (Debaryomyces hansenii) by using microbiological analyser mu-4200...
2. Characterization of Plasma-Polymerized 4-vinyl pyridine on Poly(Ethylene Terephthalate) film for anti-microbial properties
DEFF Research Database (Denmark)
Jiang, Juan; Winther-Jensen, Bjørn; Kjær, Erik Michael
2005-01-01
As an efficient way to create an anti-bacterial function on polymer surfaces, we have used plasma polymerisation to create a poly-4-vinyl-pyridine coating on the surface of a common polymer, PET, a polymerisation process that we have shown also works well on several other polymers. We have found....... The mechanical strength of the bond between the substrate and the surface layer has been tested by several methods, and the antibacterial effect of the surface layer with and without silver nano particles has been estimated by measuring electrical resistance as a function of time. The bacteria investigated were...
3. A label-free multi-functionalized electrochemical aptasensor based on a Fe_3O_4@3D-rGO@plasma-polymerized (4-vinyl pyridine) nanocomposite for the sensitive detection of proteins in whole blood
International Nuclear Information System (INIS)
Fang, Shaoming; Dong, Xiaodong; Liu, Shunli; Penng, Donglai; He, Linghao; Wang, Minghua; Fu, Guodong; Feng, Xiaozhong; Zhang, Zhihong
2016-01-01
In this paper, we report a novel label-free electrochemical aptasensor for detecting proteins in whole blood based on a three-component nanocomposite, in which ferriferrous oxide and three-dimensional graphene nanocomposite were modified with the plasma-polymerized 4-vinyl pyridine (Fe_3O_4@3D-rGO@PP4VP). In this novel sensing strategy, large amounts of amino groups in PP4VP facilitated the immobilization of aptamer strands via the strong electrostatic interaction between positively charged ammonium groups of the nanocomposites and negatively charged phosphate groups of aptamers. In the presence of thrombin, LYS (LYS), and platelet-derived growth factor-BB (PDGF-BB), the adsorbed aptamer strands on the developed nanocomposite surface caught the targeted proteins at the electrode interface. The aptamer preferred to be a barrier for electrons and inhibited electron transfer, leading to the decreased peak current of cyclic voltammetry measurements and the increased electron transfer resistance of electrochemical impedance spectroscopy. The determination of the thrombin, PDGF-BB, and LYS concentrations with this novel strategy showed low detection limits of 4.5, 29.4, and 14 pg·mL"−"1, and the analytical ranges extend from 0.01 to 50, 0.1 to 100, and 0.1 to 200 ng·mL"−"1, respectively. The resultant aptasensor exhibited high selectivity, acceptable reproducibility, and stability toward thrombin. The aptasensor could be used to detect thrombin in whole blood samples, thereby suggesting its possible application in clinical settings.
4. Characterization of Functionalized Acrylic acid /4- Vinyl Pyridine Graft Copolymers
International Nuclear Information System (INIS)
Kamal, H.; Mahmoud, Gh.A.; Hegazy, D.E.
2009-01-01
Properties and characterization of the membranes prepared by radiation grafting of acrylic acid (AAc) or/ and 4-vinyl pyridine (4VP) onto low density polyethylene (LDPE) and polypropylene (PP) films were carried out. The FTIR spectra for the grafted membranes were studied to evaluate the structure change as a result of grafting. The swelling behaviour of the graft copolymer in methanol was studied. It was found that the grafting of AAc and/ or 4- VP onto LDPE and PP resulted in introducing good hydrophilic properties to such polymer substrates. The hydrophilic properties were directly proportional to the amount of functional groups. The mechanical properties (Young's modulus, elongation percent and tensile strength) of the grafted membranes also, have been investigated. As the grafting degree increases, the modulus also increases. Increasing the hydrophilicity of the membranes by chemical treatment enhances its mechanical properties. The thermal parameters of the grafted membranes such as δH m1 . δH m2 , and T rc have been also studied by using DSC
5. Nuclear magnetic resonance and relaxation studies of the structure and segmental motions of 4-vinyl-pyridinic polymers in solution
International Nuclear Information System (INIS)
Ghesquiere, Denis
1978-01-01
The poly 4-vinylpyridine, its quaternized products from HBr and n-alkyl-bromides, and its N-oxide form have been investigated by nuclear magnetic resonance of proton at 100 and 250 MHz and carbon-13 at 25.15 MHz, The 1 H and 13 C relaxation data of poly-vinylpyridine and its ionized form have been correlated with conformational calculations. They have been interpreted in terms of an isotropic motion of the macromolecular segments introducing a correlation times distribution and of an oscillation motion of the pyridyl groups. The same treatment have been used for the 13 C relaxation data of the poly 4- vinyl-pyridines quaternized at various rates by n-alkyl-bromides. The 13 C relaxation times in the side-chains have been interpreted first by semi-empirical equations assuming an exponential gradient of the diffusion coefficients along them, and also by a Monte Carlo simulation of the motions. The results have shown that the quaternization induces a strong rigidity of the macromolecular backbone and that the dominant effect is the electrostatic interactions. On the other hand it seems that the motion of pyridyl rings is not affected. Moreover we have found a range of oscillation amplitudes in agreement with conformational energy calculations and the results obtained from a conformational study of the poly 4-vinylpyridine N-oxide by 1 H and 13 C NMR contact shifts induced by Ni II paramagnetic ions. (author) [fr
6. ILC (ionic liquid colloids) based on p(4-VP) (poly(4-vinyl pyridine)) microgels: Synthesis, characterization and use in hydrogen production
International Nuclear Information System (INIS)
Sahiner, Nurettin; Turhan, Tugce; Lyon, L. Andrew
2014-01-01
In this study for the first time p(4-VP) (poly(4-vinyl pyridine)) colloidal ionic liquid particles derived from 4-VP (4-vinyl pyridine) are reported, used in the preparation of a catalyst system by loading metal salts such as CoCl 2 and NiCl 2 from ethyl alcohol solutions into the modified p(4-VP) particles, and used for hydrogen generation from NaOH-free hydrolysis of NaBH 4 . Colloidal ionic liquids containing 0.054 mmol Co and Ni were used in NaOH-free hydrolysis of 0.30 g NaBH 4 in 50 mL water at 40 °C and 1000 rpm mixing rate. The reaction rates relating to hydrolysis of NaBH 4 were 3148 (mL H 2 ) (min) −1 (g of Co) −1 for Co, and 1803 (mL H 2 ) (min) −1 (g of Ni) −1 for Ni. The effect of metal loading time, NaBH 4 concentration, temperature, and kinetic parameters were also investigated. The activation energy, enthalpy, and activation entropy for the reaction of NaBH 4 in the presence of the colloidal dicationic catalyst system were calculated as 43.98 kJ/mol, 40.38 kJ/mol, and −178.22 J/mol.K, respectively. - Highlights: • Microgel Ionic liquid colloid reactors for H 2 production. • P(4-VP) microgel ILC (ionic liquid colloid). • Modified microgel for green energy. • Ionic liquid microgel embedding metals salts NaBH 4 hydrolysis. • Ionic liquid microgel catalyst systems
7. Radiation grafting of pH-sensitive acrylic acid and 4-vinyl pyridine onto nylon-6 using one- and two-step methods
International Nuclear Information System (INIS)
Ortega, Alejandra; Alarcón, Darío; Muñoz-Muñoz, Franklin; Garzón-Fontecha, Angélica; Burillo, Guillermina
2015-01-01
Acrylic acid (AAc) and 4-vinyl pyridine (4VP) were γ-ray grafted onto nylon-6 (Ny 6 ) films via pre-irradiation oxidative method. These monomers were grafted using a one-step method to render Ny 6 -g–(AAc/4VP). A two-step or sequential method was used to render (Ny 6 -g–AAc)-g–4VP. Random copolymer branches were obtained when the grafting was carried out via one-step method using the two monomers together. The two-step method was applied to graft chains of 4VP on both Ny 6 substrate and previously grafted AAc chains (Ny 6 -g–AAc). The two types of binary copolymers synthesized were characterized to determine the amount of grafted polymers, the thermal behavior (DSC and TGA), the surface composition (XPS), and the pH responsiveness. In the two-step process, it is possible to achieve a higher graft yield, better control of the amount of each monomer, good reversibility in the swelling/deswelling process and shorter time to achieve equilibrium swelling. - Highlights: • A new binary graft of 4VP and AAc onto Ny 6 films was synthesized by γ-radiation. • The binary grafted material has potential application for heavy ion retention. • The two-step method shows better conditions in swelling and reversibility properties. • Surface distribution of monomers was evaluate by XPS characterization
8. Fabrication of 3D interconnected porous TiO{sub 2} nanotubes templated by poly(vinyl chloride-g-4-vinyl pyridine) for dye-sensitized solar cells
Energy Technology Data Exchange (ETDEWEB)
Koh, Joo Hwan; Koh, Jong Kwan; Seo, Jin Ah; Kim, Jong Hak [Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Shin, Jong-Shik, E-mail: [email protected] [Department of Biotechnology, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)
2011-09-07
Porous TiO{sub 2} nanotube arrays with three-dimensional (3D) interconnectivity were prepared using a sol-gel process assisted by poly(vinyl chloride-graft-4-vinyl pyridine), PVC-g-P4VP graft copolymer and a ZnO nanorod template. A 7 {mu}m long ZnO nanorod array was grown from the fluorine-doped tin oxide (FTO) glass via a liquid phase deposition method. The TiO{sub 2} sol-gel solution templated by the PVC-g-P4VP graft copolymer produced a random 3D interconnection between the adjacent ZnO nanorods during spin coating. Upon etching of ZnO, TiO{sub 2} nanotubes consisting of 10-15 nm nanoparticles were generated, as confirmed by wide-angle x-ray scattering (WAXS), energy-filtering transmission electron microscopy (EF-TEM) and field-emission scanning electron microscopy (FE-SEM). The ordered and interconnected nanotube architecture showed an enhanced light scattering effect and increased penetration of polymer electrolytes in dye-sensitized solar cells (DSSC). The energy conversion efficiency reached 1.82% for liquid electrolyte, and 1.46% for low molecular weight (M{sub w}) and 0.74% for high M{sub w} polymer electrolytes.
9. Plasma polymerization by Softplasma
DEFF Research Database (Denmark)
Jiang, J.; Wu, Zhenning; Benter, Maike
2008-01-01
, external electrode, and electrodeless microwave or high frequency reactors. [3] Softplasma™ is an internal electrode plasma setup powered by low frequenc~ gower supply. It was developed in late 90s for surface treatment of silicone rubber. [ ]- 5] It is a low pressure, low electron density, 3D homogenous......In the late 19th century, the first depositions - known today as plasma polymers, were reported. In the last century, more and more research has been put into plasma polymers. Many different deposition systems have been developed. [1, 2] Shi F. F. broadly classified them into internal electrode...... plasma. In this study, we are presenting the surface modification"pf polymers by plasma polymerization using Softplasma™. Softplasma™ can be used for two major types of polymerization: polymerization of vinyl monomers, where plasma acts as initiator; chemical vapour deposition, where plasma acts...
10. A fixed cations and low Tg polymer: the poly(4-vinyl-pyridine) quaternized by poly(ethylene oxide) links. Conductivity study; Un electrolyte polymere a cations fixes et bas Tg: les poly(4-vinylpyridine) quaternisees par des chainons de poly(oxyde dethylene). Etude de la conductivite
Energy Technology Data Exchange (ETDEWEB)
Gramain, Ph. [Ecole Nationale Superieure de Chimie de Montpellier, 34 (France); Frere, Y. [Centre National de la Recherche Scientifique (CNRS), 67 - Strasbourg (France). Institut Charles Sadron
1996-12-31
The spontaneous ionic polymerization of 4-vinyl-pyridine in presence of mono-tosylated or bromated short chains of poly(ethylene oxide)-(PEO) is used to prepare amorphous comb-like poly-cations with low Tg. The polymer electrolyte properties of these new structures have been studied without any addition of salts. The ionic conductivity of these fixed cation poly-electrolytes depends on the length of the grafted PEO and varies from 10{sup -7} to 10{sup -4} S/cm between 25 and 80 deg. C. It is only weakly dependent on the nature of the cation but it is controlled by the movements of the pyridinium cation which are facilitated by the plastifying effect of the POE chains which do not directly participate to the ionic transport. (J.S.) 17 refs.
11. A fixed cations and low Tg polymer: the poly(4-vinyl-pyridine) quaternized by poly(ethylene oxide) links. Conductivity study; Un electrolyte polymere a cations fixes et bas Tg: les poly(4-vinylpyridine) quaternisees par des chainons de poly(oxyde dethylene). Etude de la conductivite
Energy Technology Data Exchange (ETDEWEB)
Gramain, Ph [Ecole Nationale Superieure de Chimie de Montpellier, 34 (France); Frere, Y [Centre National de la Recherche Scientifique (CNRS), 67 - Strasbourg (France). Institut Charles Sadron
1997-12-31
The spontaneous ionic polymerization of 4-vinyl-pyridine in presence of mono-tosylated or bromated short chains of poly(ethylene oxide)-(PEO) is used to prepare amorphous comb-like poly-cations with low Tg. The polymer electrolyte properties of these new structures have been studied without any addition of salts. The ionic conductivity of these fixed cation poly-electrolytes depends on the length of the grafted PEO and varies from 10{sup -7} to 10{sup -4} S/cm between 25 and 80 deg. C. It is only weakly dependent on the nature of the cation but it is controlled by the movements of the pyridinium cation which are facilitated by the plastifying effect of the POE chains which do not directly participate to the ionic transport. (J.S.) 17 refs.
12. Reverse-osmosis membranes by plasma polymerization
Science.gov (United States)
Hollahan, J. R.; Wydeven, T.
1972-01-01
Thin allyl amine polymer films were developed using plasma polymerization. Resulting dry composite membranes effectively reject sodium chloride during reverse osmosis. Films are 98% sodium chloride rejective, and 46% urea rejective.
13. A new lithography of functional plasma polymerized thin films
International Nuclear Information System (INIS)
Kim, Sung-O
2001-01-01
The preparation of the resist for the vacuum lithography was carried out by plasma polymerization. The resist manufactured by plasma polymerization is a monomer produced by MMA (Methyl methacrylate). The functional groups of MMA appeared in the PPMMA (Plasma Polymerized Methyl methacrylate) as well, and this was confirmed through an analysis using FT-IR. The polymerization rate increased as a function of the plasma power and decreased as a function of the system pressure. The sensitivity and contrast of the plasma polymerized thin films were 15 μC/cm2 and 4.3 respectively. The size of the pattern manufactured by Vacuum Lithography using the plasma polymerized thin films was 100 nm
14. Biotransformation of ferulic acid to 4-vinyl guaiacol by Lactobacillus ...
African Journals Online (AJOL)
Continuously growing demand for natural flavors has led to a tremendous increase in biotransformation process employing microorganisms of different genera using ferulic acid (FA) as the precursor. In this study, potential of Lactobacillus farciminis (ATCC 29644) for biotransformation of FA to 4-vinyl guaiacol (4VG) was ...
15. Novel polymer coatings based on plasma polymerized 2-methoxyethyl acrylate
DEFF Research Database (Denmark)
Wu, Zhenning; Jiang, Juan; Benter, Maike
2008-01-01
plasma system[4]. The system named SoftPlasma™ is equipped with unique three-phase pulsed AC voltage. Low energy plasma polymerization has almost no thermal load for sensitive polymer materials[5]. Plasma polymerized coatings are highly cross-linked, pin-hole free and provide hydrophilic or hydrophobic...... properties[4-6]. We have exploited these possibilities and prepared plasma polymerized 2-methoxyethyl acrylate (PPMEA) coatings on various polymer substrates. The PPMEA coatings were optimized using various plasma polymerization conditions and characterized by X-ray photoelectron spectroscopy......, Fouriertransform infrared spectroscopy, Atomic force spectroscopy and Water contact-angle measurements. The microstructures ofPPMEA coatings with different thicknesses were also studied. For practical applications in mind, the coating stability was tested in different media (air, water, acetone, phosphate...
16. Properties of amine-containing coatings prepared by plasma polymerization
Czech Academy of Sciences Publication Activity Database
Choukourov, A.; Biederman, H.; Kholodkov, I.; Slavínská, D.; Trchová, Miroslava; Hollander, A.
2004-01-01
Roč. 92, č. 2 (2004), s. 979-990 ISSN 0021-8995 R&D Projects: GA MŠk ME 554 Institutional research plan: CEZ:AV0Z4050913 Keywords : plasma polymerization * thin films * functionalization Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.021, year: 2004
17. A plasma polymerization technique to overcome cerebrospinal fluid shunt infections
Energy Technology Data Exchange (ETDEWEB)
Coekeliler, D [Plasma Aided Bioengineering and Biotechnology Research Laboratory, Engineering Faculty, Hacettepe University, 06532, Ankara (Turkey); Caner, H [Department of Neurosurgery, School of Medicine, Baskent University, 06610, Ankara (Turkey); Zemek, J [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53, Prague, Czech Republic (Czech Republic); Choukourov, A [Department of Macromolecular Physics, Charles University, V Holesovickach 2, 18000 Prague (Czech Republic); Biederman, H [Department of Macromolecular Physics, Charles University, V Holesovickach 2, 18000 Prague (Czech Republic); Mutlu, M [Plasma Aided Bioengineering and Biotechnology Research Laboratory, Engineering Faculty, Hacettepe University, 06532, Ankara (Turkey)
2007-03-01
Prosthetic devices, mainly shunts, are frequently used for temporary or permanent drainage of cerebrospinal fluid. The pathogenesis of shunt infection is a very important problem in modern medicine and generally this is characterized by staphylococcal adhesion to the cerebrospinal fluid shunt surfaces. In this paper, the prevention of the attachment of test microorganism Staphylococcus epidermidis on the cerebrospinal fluid shunt surfaces by 2-hydroxyethylmethacrylate (HEMA) precursor modification in the plasma polymerization system, is reported. Different plasma polymerization conditions (RF discharge power 10-20-30 W, exposure time 5-10-15 min) were employed during the surface modification. The surface chemistry and topology of unmodified and modified shunts was characterized by x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also, static contact angle measurements were performed to state the change of surface hydrophilicity. All samples were tested in vitro with Staphylococcus epidermidis. A plasma-polymerized HEMA film (PP HEMA) was found to be an alternative simple method to decrease the microorganism attachment and create bacterial anti-fouling surfaces. The attachment of the model microorganism Staphylococcus epidermidis on the shunt surface modified by PP HEMA at 20 W and 15 min was reduced 62.3% if compared to the unmodified control surface of the shunt.
18. Plasma polymerized high energy density dielectric films for capacitors
Science.gov (United States)
Yamagishi, F. G.
1983-01-01
High energy density polymeric dielectric films were prepared by plasma polymerization of a variety of gaseous monomers. This technique gives thin, reproducible, pinhole free, conformable, adherent, and insoluble coatings and overcomes the processing problems found in the preparation of thin films with bulk polymers. Thus, devices are prepared completely in a vacuum environment. The plasma polymerized films prepared all showed dielectric strengths of greater than 1000 kV/cm and in some cases values of greater than 4000 kV/cm were observed. The dielectric loss of all films was generally less than 1% at frequencies below 10 kHz, but this value increased at higher frequencies. All films were self healing. The dielectric strength was a function of the polymerization technique, whereas the dielectric constant varied with the structure of the starting material. Because of the thin films used (thickness in the submicron range) surface smoothness of the metal electrodes was found to be critical in obtaining high dielectric strengths. High dielectric strength graft copolymers were also prepared. Plasma polymerized ethane was found to be thermally stable up to 150 C in the presence of air and 250 C in the absence of air. No glass transitions were observed for this material.
19. Composite plasma polymerized sulfonated polystyrene membrane for PEMFC
Energy Technology Data Exchange (ETDEWEB)
Nath, Bhabesh Kumar; Khan, Aziz; Chutia, Joyanti, E-mail: [email protected]
2015-10-15
Highlights: • Methyl methane sulfonate (MMS) is used as the sulfonating agent. • The proton conductivity of the membrane is found to be 0.141 S cm{sup −1}. • Power density of fuel cell with styrene/MMS membrane is 0.5 W cm{sup −2}. • The membrane exhibits thermal stability up to 140 °C. - Abstract: This work presents the introduction of an organic compound methyl methane sulfonate (MMS) for the first time in fabrication of polystyrene based proton exchange membrane (PEM) by plasma polymerization process. The membrane is fabricated by co-polymerizing styrene and MMS in capacitively coupled continuous RF plasma. The chemical composition of the plasma polymerized polymer membrane is investigated using Fourier Transform Infrared Spectroscopy which reveals the formation of composite structure of styrene and MMS. The surface morphology studied using AFM and SEM depicts the effect of higher partial pressure of MMS on surface topography of the membrane. The proton transport property of the membrane studied using electrochemical impedance spectroscopy shows the achievement of maximum proton conductivity of 0.141 S cm{sup −1} which is comparable to Nafion 117 membrane. Fuel cell performance test of the synthesized membrane shows a maximum power density of 500 mW cm{sup −2} and current density of 0.62 A cm{sup −2} at 0.6 V.
20. Immobilization of biomolecules to plasma polymerized pentafluorophenyl methacrylate.
Science.gov (United States)
Duque, Luis; Menges, Bernhard; Borros, Salvador; Förch, Renate
2010-10-11
Thin films of plasma polymerized pentafluorophenyl methacrylate (pp-PFM) offer highly reactive ester groups throughout the structure of the film that allow for subsequent reactions with different aminated reagents and biological molecules. The present paper follows on from previous work on the plasma deposition of pentafluorophenyl methacrylate (PFM) for optimum functional group retention (Francesch, L.; Borros, S.; Knoll, W.; Foerch, R. Langmuir 2007, 23, 3927) and reactivity in aqueous solution (Duque, L.; Queralto, N.; Francesch, L.; Bumbu, G. G.; Borros, S.; Berger, R.; Förch, R. Plasma Process. Polym. 2010, accepted for publication) to investigate the binding of a biologically active peptide known to induce cellular adhesion (IKVAV) and of biochemically active proteins such as BSA and fibrinogen. Analyses of the films and of the immobilization of the biomolecules were carried out using infrared reflection absorption spectroscopy (IRRAS), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The attachment of the biomolecules on pulsed plasma polymerized pentafluorophenyl methacrylate was monitored using surface plasmon resonance spectroscopy (SPR). SPR analysis confirmed the presence of immobilized biomolecules on the plasma polymer and was used to determine the mass coverage of the peptide and proteins adsorbed onto the films. The combined analysis of the surfaces suggests the covalent binding of the peptide and proteins to the surface of the pp-PFM.
1. Interaction between poly(vinyl pyridine) and poly(2,6-dimethyl-1,4-phenylene oxide) : A copolymer blend miscibility study
NARCIS (Netherlands)
de Wit, Joost; van Ekenstein, Gert Alberda; ten Brinke, Gerrit
2007-01-01
The phase behavior of blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with random copolymers of styrene and 2-vinyl pyridine, Poly(S-co-2VP), as well as with random copolymers of styrene and 4-vinyl pyridine, Poly(S-co-4VP), has been investigated in order to estimate the values of the
2. Ultrasmooth plasma polymerized coatings for laser-fusion targets
International Nuclear Information System (INIS)
Letts, S.A.; Myers, D.W.; Witt, L.A.
1980-01-01
Coatings for laser fusion targets were deposited up to 135 μm thick by plasma polymerization onto 140 μm diameter DT filled glass microspheres. Ultrasmooth surfaces (no defect higher than 0.1 μm) were achieved by eliminating particulate contamination. Process generated particles were eliminated by determining the optimum operating conditions of power, gas flow, and pressure, and maintaining these conditions through feedback control. From a study of coating defects grown over known surface irregularities, a quantitative relationship between irregularity size, film thickness, and defect size was determined. This relationship was used to set standards for the maximum microshell surface irregularity tolerable in the production of hydrocarbon or fluorocarbon coated laser fusion targets
3. Ultrasmooth plasma polymerized coatings for laser fusion targets
International Nuclear Information System (INIS)
Letts, S.A.; Myers, D.W.; Witt, L.A.
1980-01-01
Coatings for laser fusion were deposited up to 135μm thick by plasma polymerization onto 140 μm diameter DT filled glass microspheres. Ultrasmooth surfaces (no defect higher than 0.1 μm) were achieved by eliminating particulate contamination. Process generated particles were eliminated by determining the optimum operating conditions of power (20 watts), gas flow (0.3 sccm trans-2-butene, 10.0 sccm hydrogen), and pressure (75 millitorr), and maintaining these conditions through feedback control. From a study of coating defects grown over known surface irregularities, a quantitative relationship between irregularity size, film thickness, and defect size was determined. This relationship was used to set standards for the maximum microshell surface irregularity tolerable in the production of hydrocarbon or fluorocarbon coated laser fusion targets
4. Controlling the Plasma-Polymerization Process of N-Vinyl-2-pyrrolidone
DEFF Research Database (Denmark)
Norrman, Kion; Winther-Jensen, Bjørn
2005-01-01
N-vinyl-2-pyrrolidone was plasma-polymerized on glass substrates using a pulsed AC plasma. Pulsed AC plasma produces a chemical surface structure different from that produced by conventional RF plasma; this is ascribed to the different power regimes used. A high degree of control over the structure...... of the chemical surface was obtained using pulsed AC plasma, as shown by ToF-SIMS. It is demonstrated how the experimental conditions to some extent control the chemical structure of the plasma-polymerized film, e.g., film thickness, density of post-plasma-polymerized oligomeric chains, and the density of intact...
5. Resonance Raman assignment and evidence for noncoupling of individual 2- and 4-vinyl vibrational modes in a monomeric cyanomethemoglobin
International Nuclear Information System (INIS)
Gersonde, K.; Yu, N.T.; Lin, S.H.; Smith, K.M.; Parish, D.W.
1989-01-01
We have investigated the resonance Raman spectra of monomeric insect cyanomethemoglobins (CTT III and CTT IV) reconstituted with (1) protohemes IX selectively deuterated at the 4-vinyl as well as the 2,4-divinyls, (2) monovinyl-truncated hemes such as pemptoheme (2-hydrogen, 4-vinyl) and isopemptoheme (2-vinyl, 4-hydrogen), (3) symmetric hemes such as protoheme III (with 2- and 3-vinyls) and protoheme XIII (with 1- and 4-vinyls), and (4) hemes without 2- and 4-vinyls such as mesoheme IX, deuteroheme IX, 2,4-dimethyldeuteroheme IX, and 2,4-dibromodeuteroheme IX. Evidence is presented that the highly localized vinyl C = C stretching vibrations at the 2- and 4-positions of the heme in these cyanomet CTT hemoglobins are noncoupled and inequivalent; i.e., the 1631- and 1624-cm-1 lines have been assigned to 2-vinyl and 4-vinyl, respectively. The elimination of the 2-vinyl (in pemptoheme) or the 4-vinyl (in isopemptoheme) does not affect the C = C stretching frequency of the remaining vinyl. Furthermore, two low-frequency vinyl bending modes at 412 and 591 cm-1 exhibit greatly different resonance Raman intensities between 2-vinyl and 4-vinyl. The observed intensity at 412 cm-1 is primarily derived from 4-vinyl, whereas the 591-cm-1 line results exclusively from the 2-vinyl. Again, there is no significant coupling between 2-vinyl and 4-vinyl for these two bending modes
6. Surface modification of nanoporous alumina membranes by plasma polymerization
Energy Technology Data Exchange (ETDEWEB)
Losic, Dusan; Cole, Martin A; Dollmann, Bjoern; Vasilev, Krasimir; Griesser, Hans J [Ian Wark Research Institute, University of South Australia, Mawson Lakes, Adelaide, SA 5095 (Australia)], E-mail: [email protected]
2008-06-18
The deposition of plasma polymer coatings onto porous alumina (PA) membranes was investigated with the aim of adjusting the surface chemistry and the pore size of the membranes. PA membranes from commercial sources with a range of pore diameters (20, 100 and 200 nm) were used and modified by plasma polymerization using n-heptylamine (HA) monomer, which resulted in a chemically reactive polymer surface with amino groups. Heptylamine plasma polymer (HAPP) layers with a thickness less than the pore diameter do not span the pores but reduce their diameter. Accordingly, by adjusting the deposition time and thus the thickness of the plasma polymer coating, it is feasible to produce any desired pore diameter. The structural and chemical properties of modified membranes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and x-ray electron spectroscopy (XPS). The resultant PA membranes with specific surface chemistry and controlled pore size are applicable for molecular separation, cell culture, bioreactors, biosensing, drug delivery, and engineering complex composite membranes.
7. Initial biocompatibility of plasma polymerized hexamethyldisiloxane films with different wettability
Science.gov (United States)
Krasteva, N. A.; Toromanov, G.; Hristova, K. T.; Radeva, E. I.; Pecheva, E. V.; Dimitrova, R. P.; Altankov, G. P.; Pramatarova, L. D.
2010-11-01
Understanding the relationships between material surface properties, behaviour of adsorbed proteins and cellular responses is essential to design optimal material surfaces for tissue engineering. In this study we modify thin layers of plasma polymerized hexamethyldisiloxane (PPHMDS) by ammonia treatment in order to increase surface wettability and the corresponding biological response. The physico-chemical properties of the polymer films were characterized by contact angle (CA) measurements and Fourier Transform Infrared Spectroscopy (FTIR) analysis.Human umbilical vein endothelial cells (HUVEC) were used as model system for the initial biocompatibility studies following their behavior upon preadsorption of polymer films with three adhesive proteins: fibronectin (FN), fibrinogen (FG) and vitronectin (VN). Adhesive interaction of HUVEC was evaluated after 2 hours by analyzing the overall cell morphology, and the organization of focal adhesion contacts and actin cytoskeleton. We have found similar good cellular response on FN and FG coated polymer films, with better pronounced vinculin expression on FN samples while. Conversely, on VN coated surfaces the wettability influenced significantly initial celular interaction spreading. The results obtained suggested that ammonia plasma treatment can modulate the biological activity of the adsorbed protein s on PPHMDS surfaces and thus to influence the interaction with endothelial cells.
8. Surface modification of nanoporous alumina membranes by plasma polymerization
International Nuclear Information System (INIS)
Losic, Dusan; Cole, Martin A; Dollmann, Bjoern; Vasilev, Krasimir; Griesser, Hans J
2008-01-01
The deposition of plasma polymer coatings onto porous alumina (PA) membranes was investigated with the aim of adjusting the surface chemistry and the pore size of the membranes. PA membranes from commercial sources with a range of pore diameters (20, 100 and 200 nm) were used and modified by plasma polymerization using n-heptylamine (HA) monomer, which resulted in a chemically reactive polymer surface with amino groups. Heptylamine plasma polymer (HAPP) layers with a thickness less than the pore diameter do not span the pores but reduce their diameter. Accordingly, by adjusting the deposition time and thus the thickness of the plasma polymer coating, it is feasible to produce any desired pore diameter. The structural and chemical properties of modified membranes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and x-ray electron spectroscopy (XPS). The resultant PA membranes with specific surface chemistry and controlled pore size are applicable for molecular separation, cell culture, bioreactors, biosensing, drug delivery, and engineering complex composite membranes
9. Optical characterization of composite layers prepared by plasma polymerization
International Nuclear Information System (INIS)
Radeva, E; Hikov, T; Mitev, D; Pramatarova, L; Stroescu, H; Nicolescu, M; Gartner, M; Presker, R
2016-01-01
Thin composite layers from polymer/nanoparticles (Ag-nanoparticles and detonation nanodiamonds) were prepared by plasma polymerization process on the base of hexamethyldisiloxane. The variation of the layer composition was achieved by changing the type of nanoparticles. The optical measurement techniques used were UV-VIS-NIR ellipsometry (SE), Fourier-transformed infrared spectroscopy (FTIR) and Raman spectroscopy. The values of the refractive index determined are in the range 1.30 to 1.42. All samples are transparent with transmission between 85-95% and very smooth. The change in Raman and FTIR spectra of the composites verify the expected bonding between polymer and diamond nanoparticles due to the penetration of the fillers in the polymer matrix. The comparison of the spectra of the corresponding NH3 plasma treated composites revealed that the composite surface becomes more hydrophilic. The obtained results indicate that preparation of layers with desired compositions is possible at a precise control of the detonation nanodiamond materials. (paper)
10. Plasma polymerization at different positions in an asymmetric ethylene discharge
International Nuclear Information System (INIS)
Trieschmann, Jan; Hegemann, Dirk
2011-01-01
The characteristics of plasma polymerization are investigated in an asymmetric, capacitively coupled plasma discharge. Here, the deposition in different plasma zones, i.e. on the driven electrode, within the plasma bulk and the plasma sheath as well as approximately at the plasma-sheath edge, is investigated. Principal expectations are perfectly met, though new interesting dependences of the obtained a-C : H coatings with respect to film properties and deposition rates are also found. That is, the deposition rates as measured on thin, small glass slides placed directly on the electrode are considerably higher than everywhere else in the plasma, yet only single-sided. In contrast, the deposition rates on the samples within the plasma are lowered depending on the exact placement, while a double-sided coating is obtained. Furthermore, film properties, such as the film density, are highly dependent on the sample placement in the plasma, which can even be higher under floating conditions. With simple physical arguments we are able to show the relations between the deposition rate and the energy input into the plasma as well as between the energy density during film growth and the film density itself.
11. Characteristics of polyimide-based composite membranes fabricated by low-temperature plasma polymerization
International Nuclear Information System (INIS)
Dung Thi Tran; Mori, Shinsuke; Suzuki, Masaaki
2008-01-01
Composite membranes were prepared by the deposition of plasma-polymerized allylamine films onto a porous polyimide substrate. The relationship between the plasma conditions and the membrane characteristics was described in terms of monomer flow rate, plasma discharge power, plasma polymerization time, and so on. Scanning electron microscope (SEM) images indicate that the thickness of the plasma polymer layer increased and the membrane skin pore size decreased gradually with the increasing of plasma polymerization time. Fourier transform infrared (FTIR) spectra demonstrate the appearance of amine groups in the plasma deposited polymer and the contact angle measurements indicate that the hydrophilicity of the membrane surfaces increased significantly after plasma polymerization. The composite membranes can reject salt from sodium chloride feed solution, and membrane separation performance depends strongly on the plasma conditions applied during the preparation of the plasma deposited polymer films
12. Micro patterning of cell and protein non-adhesive plasma polymerized coatings for biochip applications
DEFF Research Database (Denmark)
Bouaidat, Salim; Berendsen, C.; Thomsen, P.
2004-01-01
Micro scale patterning of bioactive surfaces is desirable for numerous biochip applications. Polyethyleneoxide-like (PEO-like) coating with non-fouling functionality has been deposited using low frequency AC plasma polymerization. The non-fouling properties of the coating were tested with human c...... and versatility of the plasma-polymerized coatings, make this technology highly suitable for bio-MEMS and biochip applications, where patterned high contrast non-fouling surfaces are needed....
13. Polyanionic pH-responsive polystyrene-b-poly(4-vinyl pyridine-N-oxide) isoporous membranes
KAUST Repository
Shevate, Rahul
2015-12-01
Recently isoporous block copolymer (BCP) membranes obtained by non-solvent induced phase separation gained a lot of attention due to their highly ordered surface layer, high flux and superior separation properties. These polystyrene-b-poly-4-vinylpyridine (PS-b-P4VP) based membranes showed a strong flux dependence of pH; pores closed at low pH and opened at high pH. The pH-response could now be reversed by a simple post modification; pores are now opening at low pH and closing at high pH. The original membrane was transformed into a polyanionic pH responsive membrane in a one step chemical modification without affecting the isoporous surface morphology. A polystyrene-b-poly-4-vinylpyridine-N-oxide (PS-b-P4VPN-oxide) membrane is obtained by selective oxidation of the PS-b-P4VP membrane. The in situ generated peracid obtained by reacting acetic acid and hydrogen peroxide is employed for oxidation. Surprisingly not only the asymmetric membrane structure with the isoporous skin was retained, but also the mechanical and chemical membrane stability was improved significantly. The modified membranes are insoluble in solvents like DMF, NMP and DMSO. Two kinds of PS-b-P4VP based isoporous membranes are available now with reverse flux response to pH. This opens the door to new interesting charge based fractionations.
14. Polyanionic pH-responsive polystyrene-b-poly(4-vinyl pyridine-N-oxide) isoporous membranes
KAUST Repository
Shevate, Rahul; Karunakaran, Madhavan; Kumar, Mahendra; Peinemann, Klaus-Viktor
2015-01-01
, but also the mechanical and chemical membrane stability was improved significantly. The modified membranes are insoluble in solvents like DMF, NMP and DMSO. Two kinds of PS-b-P4VP based isoporous membranes are available now with reverse flux response to p
15. Synthesis, Characterization and Application of Poly (Styrene-4- Vinyl Pyridine) Membranes Assembled With Single-Wall Carbon Nanotubes
KAUST Repository
He, Haoze
2011-06-01
Poly(styrene‐4‐vinylpyridine) (PS‐P4VP) isoporous membranes were prepared and their properties were evaluated in this research. The solution was prepared by dissolving PS‐P4VP polymer with necessary additives into a 1:1:1 1,4‐dioxane – N,N‐dimethyl formamide – tetrahydrofuran (DOX‐DMF‐THF, DDT) solvent. Then 0.5‐1.0 mL of the primary solution was cast onto the non‐woven substrate membrane on a glass slide, evaporated for 15‐20 sec and immersed into de‐ionized water for more than 30 min for the solidification of isoporous structure and for the formation of the primary films, which could be post‐processed in different ways for different tests. The membrane surface presents a well‐ordered, hexagonal self‐assembly structure, which is fit for aqueous and gaseous filtration. The pore size of the isoporous surface is 30~40 nm. The pore size is also sensitive to [H+] in the solution and a typical pair of S‐shape pH‐correlation curves with significant hysteresis was found. Four techniques were tried to improve the properties of the membranes in this research: 1) 1,4‐diiodobutane was introduced to chemically change the structure as a cross‐linking agent. 2) single‐wall carbon nanotube (SWCNT) was linked to the membranes in order to strengthen the stability and rigidity and to reduce the hysteresis. 3) Homo‐poly(4‐vinylpyridine) (homo‐P4VP) was added and inserted into the PS‐P4VP micelles to affect the pore size and surface structure. 4) Copper acetate (Cu(Ac)2) was used as substitute of dioxane to prepare the Cu(Ac)2‐DMF‐THF (CDT) mixed solvent, for a better SWCNT dispersion. All the possible improvements were judged by the atomic force microscopy (AFM) images, water and gas flux tests and pH‐correlation curves. The introduction of SWCNT was the most important innovation in this research and is promising in future applications.
16. Modification of glass fibers to improve reinforcement: a plasma polymerization technique
Czech Academy of Sciences Publication Activity Database
Çökeliler, D.; Erkut, S.; Zemek, Josef; Biederman, H.; Mutlu, M.
2007-01-01
Roč. 23, č. 3 (2007), s. 335-342 ISSN 0109-5641 Institutional research plan: CEZ:AV0Z10100521 Keywords : plasma polymerization * glos-discharge * E-glass fibros * ethylendiamine * 2-hydroxyethyl methacrystalate * triethyleneglycoldimethylether * fibre-reinforced composite ( FRC) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.990, year: 2007
17. The influence of pulse parameters on film composition during pulsed plasma polymerization of diaminocyclohexane
Czech Academy of Sciences Publication Activity Database
Choukourov, A.; Biederman, H.; Slavínská, D.; Trchová, Miroslava; Hollander, A.
174-175, - (2003), s. 863-866 ISSN 0257-8972. [International Conference on Plasma Surface Engineering /8./. Garmisch-Partenkirchen, 09.09.2002-13.09.2002] R&D Projects: GA AV ČR KSK4050111 Keywords : plasma polymerization * chemical derivation * primary and secondary amino groups Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.410, year: 2003
18. Plasma-polymerized alkaline anion-exchange membrane: Synthesis and structure characterization
International Nuclear Information System (INIS)
Hu Jue; Meng Yuedong; Zhang Chengxu; Fang Shidong
2011-01-01
After-glow discharge plasma polymerization was developed for alkaline anion-exchange membranes synthesis using vinylbenzyl chloride as monomer. X-ray photoelectron spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy were used to characterize the chemical structure properties of plasma-polymerized membranes. Ion-exchange capacities of quaternized poly(vinylbenzyl chloride) (QPVBC) membranes were measured to evaluate their capability of hydroxyl ion transport. A mechanism of plasma polymerization using VBC as monomer that accounts for the competitive effects of free radicals polymerization and plasma ablation in the plasma polymerization process was proposed. Our results indicate that plasma discharge power influences the contents of functional groups and the structure of the plasma polymer membranes, which attribute to the coactions of polymerization and ablation. The properties of uniform morphology, good adhesion to the substrate, high thermal stability and satisfying anion conduction level suggest the potential application of QPVBC membrane deposited at discharge power of 20 W in alkaline direct methanol fuel cells.
19. Immobilization and controlled release of drug using plasma polymerized thin film
Energy Technology Data Exchange (ETDEWEB)
Myung, Sung-Woon [Department of Dental Materials, School of Dentistry, MRC Center, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju (Korea, Republic of); Jung, Sang-Chul [Department of Environmental Engineering, Sunchon National University, Sunchon 540-742 (Korea, Republic of); Kim, Byung-Hoon, E-mail: [email protected] [Department of Dental Materials, School of Dentistry, MRC Center, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju (Korea, Republic of)
2015-06-01
In this study, plasma polymerization of acrylic acid was employed to immobilize drug and control its release. Doxorubicin (DOX) was immobilized covalently on the glass surface deposited with plasma polymerized acrylic acid (PPAAc) thin film containing the carboxylic group. At first, the PPAAc thin film was coated on a glass surface at a pressure of 1.33 Pa and radio frequency (RF) discharge power of 20 W for 10 min. DOX was immobilized on the PPAAc deposition in a two environment of phosphate buffer saline (PBS) and dimethyl sulfoxide (DMSO) solutions. The DOX immobilized surface was characterized by scanning electron microscope, atomic force microscope and attenuated total reflection Fourier transform infrared spectroscopy. The DOX molecules were more immobilized in PBS than DMSO solution. The different immobilization and release profiles of DOX result from the solubility of hydrophobic DOX in aqueous and organic solutions. Second, in order to control the release of the drug, PPAAc thin film was covered over DOX dispersed layer. Different thicknesses and cross-linked PPAAc thin films by adjusting deposition time and RF discharge power were covered on the DOX layer dispersed. PPAAc thin film coated DOX layer reduced the release rate of DOX. The thickness control of plasma deposition allows controlling the release rate of drug. - Highlights: • Doxorubicin was immobilized on the surface of plasma polymerized acrylic acid thin film. • Release profile of doxorubicin was affected by aqueous and organic solutions. • Plasma polymerized acrylic acid thin film can be used to achieve controlled release.
20. Elimination of defects in plasma polymerized films used in laser fusion targets
International Nuclear Information System (INIS)
Letts, S.A.; Johnson, W.L.; Myers, D.W.; Illige, J.D.; Lorensen, L.E.; Hatcher, C.W.
1979-01-01
This study was conducted to understand and control the parameters governing the formation of defects in plasma polymerized surfaces. An inductively-coupled discharge was used as the source of activated monomer. Four types of well characterized surface irregularities were produced on glass slides which were subsequently fluorocarbon coated. Optimization of the process variables is discussed
1. Immobilization and controlled release of drug using plasma polymerized thin film
International Nuclear Information System (INIS)
Myung, Sung-Woon; Jung, Sang-Chul; Kim, Byung-Hoon
2015-01-01
In this study, plasma polymerization of acrylic acid was employed to immobilize drug and control its release. Doxorubicin (DOX) was immobilized covalently on the glass surface deposited with plasma polymerized acrylic acid (PPAAc) thin film containing the carboxylic group. At first, the PPAAc thin film was coated on a glass surface at a pressure of 1.33 Pa and radio frequency (RF) discharge power of 20 W for 10 min. DOX was immobilized on the PPAAc deposition in a two environment of phosphate buffer saline (PBS) and dimethyl sulfoxide (DMSO) solutions. The DOX immobilized surface was characterized by scanning electron microscope, atomic force microscope and attenuated total reflection Fourier transform infrared spectroscopy. The DOX molecules were more immobilized in PBS than DMSO solution. The different immobilization and release profiles of DOX result from the solubility of hydrophobic DOX in aqueous and organic solutions. Second, in order to control the release of the drug, PPAAc thin film was covered over DOX dispersed layer. Different thicknesses and cross-linked PPAAc thin films by adjusting deposition time and RF discharge power were covered on the DOX layer dispersed. PPAAc thin film coated DOX layer reduced the release rate of DOX. The thickness control of plasma deposition allows controlling the release rate of drug. - Highlights: • Doxorubicin was immobilized on the surface of plasma polymerized acrylic acid thin film. • Release profile of doxorubicin was affected by aqueous and organic solutions. • Plasma polymerized acrylic acid thin film can be used to achieve controlled release
2. Plasma polymerization surface modification of Carbon black and its effect in elastomers
NARCIS (Netherlands)
Mathew, T.; Datta, Rabin; Dierkes, Wilma K.; Talma, Auke; Ooij, W.J.; Noordermeer, Jacobus W.M.
2011-01-01
Surface modification of carbon black by plasma polymerization was aimed to reduce its surface energy in order to compatibilize the filler with various elastomers. A fullerenic carbon black was used for the modification process. Thermogravimetric analysis, wetting behavior with liquids of known
3. A state-of-the-art plasma polymerization coater for ICF targets
International Nuclear Information System (INIS)
Devine, G.; Letts, S.; Cook, R.; Brusasco, R.
1992-01-01
Increasingly stringent demands on the characteristics of plasma polymer coatings for use in Inertial Confinement Fusion (ICF) experiments have created a need for a plasma Polymerization coating system with the capability of producing a wide variety of different types of coatings as well as one that can be used to do fundamental investigations of the process conditions leading to desirable films. We report on the construction and use of just such a coating instrument. We have recognized the usefulness of computer assisted process monitoring and control, currently being developed by the semiconductor industry, in designing our own, State-of-the-art plasma polymerization device. Our system is fully computer interfaced to provide the user with the capability of collecting system parameter data over the length of the deposition experiment. The system is also designed to allow for any degree of computer control of the deposition process in the future
4. Analysis of annealed thin polymer films prepared from dichloro(methyl)phenylsilane by plasma polymerization
Czech Academy of Sciences Publication Activity Database
Cech, V.; Horvath, P.; Trchová, M.; Zemek, Josef; Matějková, Jiřina
2001-01-01
Roč. 82, - (2001), s. 2106-2112 ISSN 0021-8995 R&D Projects: GA ČR GV106/98/K013; GA ČR GA104/00/0708 Institutional research plan: CEZ:AV0Z1010914 Keywords : plasma polymerization * thin films * thermogravimetric analysis ( TSA ) * FTIR * ESCA/XPS Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.992, year: 2001
5. Immobilization/hybridization of amino-modified DNA on plasma-polymerized allyl chloride
International Nuclear Information System (INIS)
Zhang Zhihong; Feng Chuanliang
2007-01-01
The present work describes the fabrication and characterization of chloride-derivatized polymer coatings prepared by continuous wave (cw) plasma polymerization as adhesion layers in DNA immobilization/hybridization. The stability of plasma-polymerized allyl chloride (ppAC) in H 2 O was characterized by variation of the thickness of polymer films and its wettability was examined by water contact angle technique. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to study polymer matrix properties and oligonucleotide/DNA binding interaction. With the same carrier gas rate and process pressure, plasma polymers deposited at different input powers show various comparable immobilization properties; nevertheless, low input power plasma-polymerized films gives a lower sensitivity toward DNA binding than that from high input power plasma-deposited films. The following DNA immobilization on chloride-functionalized surfaces was found dependence on the macromolecular architecture of the plasma films. The hybridization between probe DNA and total mismatch target DNA shows no non-specific adsorption between target and ppAC
6. Modulation of release kinetics by plasma polymerization of ampicillin-loaded β -TCP ceramics
International Nuclear Information System (INIS)
Labay, C; Buxadera-Palomero, J; Avilés, M; Canal, C; Ginebra, M P
2016-01-01
Beta-tricalcium phosphate ( β -TCP) bioceramics are employed in bone repair surgery. Their local implantation in bone defects puts them in the limelight as potential materials for local drug delivery. However, obtaining suitable release patterns fitting the required therapeutics is a challenge. Here, plasma polymerization of ampicillin-loaded β -TCP is studied for the design of a novel antibiotic delivery system. Polyethylene glycol-like (PEG-like) coating of β -TCP by low pressure plasma polymerization was performed using diglyme as precursor, and nanometric PEG-like layers were obtained by simple and double plasma polymerization processes. A significant increase in hydrophobicity, and the presence of plasma polymer was visible on the surface by SEM and quantified by XPS. As a main consequence of the plasma polymerisation, the release kinetics were successfully modified, avoiding burst release, and slowing down the initial rate of release leading to a 4.5 h delay in reaching the same antibiotic release percentage, whilst conservation of the activity of the antibiotic was simultaneously maintained. Thus, plasma polymerisation on the surface of bioceramics may be a good strategy to design controlled drug delivery matrices for local bone therapies. (paper)
7. Amine Enrichment of Thin-Film Composite Membranes via Low Pressure Plasma Polymerization for Antimicrobial Adhesion.
Science.gov (United States)
Reis, Rackel; Dumée, Ludovic F; He, Li; She, Fenghua; Orbell, John D; Winther-Jensen, Bjorn; Duke, Mikel C
2015-07-15
Thin-film composite membranes, primarily based on poly(amide) (PA) semipermeable materials, are nowadays the dominant technology used in pressure driven water desalination systems. Despite offering superior water permeation and salt selectivity, their surface properties, such as their charge and roughness, cannot be extensively tuned due to the intrinsic fabrication process of the membranes by interfacial polymerization. The alteration of these properties would lead to a better control of the materials surface zeta potential, which is critical to finely tune selectivity and enhance the membrane materials stability when exposed to complex industrial waste streams. Low pressure plasma was employed to introduce amine functionalities onto the PA surface of commercially available thin-film composite (TFC) membranes. Morphological changes after plasma polymerization were analyzed by SEM and AFM, and average surface roughness decreased by 29%. Amine enrichment provided isoelectric point changes from pH 3.7 to 5.2 for 5 to 15 min of plasma polymerization time. Synchrotron FTIR mappings of the amine-modified surface indicated the addition of a discrete 60 nm film to the PA layer. Furthermore, metal affinity was confirmed by the enhanced binding of silver to the modified surface, supported by an increased antimicrobial functionality with demonstrable elimination of E. coli growth. Essential salt rejection was shown minimally compromised for faster polymerization processes. Plasma polymerization is therefore a viable route to producing functional amine enriched thin-film composite PA membrane surfaces.
8. Evaluation of Osseointegration of Titanium Alloyed Implants Modified by Plasma Polymerization
Directory of Open Access Journals (Sweden)
Carolin Gabler
2014-02-01
Full Text Available By means of plasma polymerization, positively charged, nanometre-thin coatings can be applied to implant surfaces. The aim of the present study was to quantify the adhesion of human bone cells in vitro and to evaluate the bone ongrowth in vivo, on titanium surfaces modified by plasma polymer coatings. Different implant surface configurations were examined: titanium alloy (Ti6Al4V coated with plasma-polymerized allylamine (PPAAm and plasma-polymerized ethylenediamine (PPEDA versus uncoated. Shear stress on human osteoblast-like MG-63 cells was investigated in vitro using a spinning disc device. Furthermore, bone-to-implant contact (BIC was evaluated in vivo. Custom-made conical titanium implants were inserted at the medial tibia of female Sprague-Dawley rats. After a follow-up of six weeks, the BIC was determined by means of histomorphometry. The quantification of cell adhesion showed a significantly higher shear stress for MG-63 cells on PPAAm and PPEDA compared to uncoated Ti6Al4V. Uncoated titanium alloyed implants showed the lowest BIC (40.4%. Implants with PPAAm coating revealed a clear but not significant increase of the BIC (58.5% and implants with PPEDA a significantly increased BIC (63.7%. In conclusion, plasma polymer coatings demonstrate enhanced cell adhesion and bone ongrowth compared to uncoated titanium surfaces.
9. Carboxymethylcellulose acetate butyrate/poly(4-vinyl-N-pentyl pyridinium bromide blends as antimicrobial coatings
Directory of Open Access Journals (Sweden)
L. S. Blachechen
2015-09-01
Full Text Available Blends of carboxymethyl cellulose acetate butyrate (CMCAB, a cellulose derivative, and poly(4-vinyl-N-pentyl pyridinium bromide (QPVP-C5, an antimicrobial polymer, were prepared by casting method and characterized by means of Fourier transform infrared vibrational spectroscopy (FTIR, scanning electron microscopy (SEM, thermogravimetric analysis (TGA, differential scanning calorimetry (DSC and contact angle measurements. Miscibility between CMCAB and QPVP-C5 was evidenced by DSC measurements of blends, which showed a single thermal event of Tg, and SEM images, which revealed homogenous morphology, regardless the blend composition. Moreover, thermal stability of QPVP-C5 was substantially enhanced, when it was mixed with CMCAB. Upon increasing the QPVP-C5 content in the blend the wettability and antimicrobial activity against Gram-positive bacteria Micrococcus luteus increased, indicating the surface enrichment by pyridinium groups. In fact, blends with 70 wt% QPVP-C5 reduced 5 log and 4 log the colony-forming units of Micrococcus luteus and Escherichia coli, respectively.
10. Synthesis and Characterization of Nanofibrous Polyaniline Thin Film Prepared by Novel Atmospheric Pressure Plasma Polymerization Technique.
Science.gov (United States)
Park, Choon-Sang; Kim, Dong Ha; Shin, Bhum Jae; Tae, Heung-Sik
2016-01-11
This work presents a study on the preparation of plasma-polymerized aniline (pPANI) nanofibers and nanoparticles by an intense plasma cloud type atmospheric pressure plasma jets (iPC-APPJ) device with a single bundle of three glass tubes. The nano size polymer was obtained at a sinusoidal wave with a peak value of 8 kV and a frequency of 26 kHz under ambient air. Discharge currents, photo-sensor amplifier, and optical emission spectrometer (OES) techniques were used to analyze the plasma produced from the iPC-APPJ device. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), gas chromatography-mass spectrometry (GC-MS), and gel permeation chromatography (GPC) techniques were used to analyze the pPANI. FE-SEM and TEM results show that pPANI has nanofibers, nanoparticles morphology, and polycrystalline characteristics. The FT-IR and GC-MS analysis show the characteristic polyaniline peaks with evidence that some quinone and benzene rings are broken by the discharge energy. GPC results show that pPANI has high molecular weight ( M w ), about 533 kDa with 1.9 polydispersity index (PDI). This study contributes to a better understanding on the novel growth process and synthesis of uniform polyaniline nanofibers and nanoparticles with high molecular weights using the simple atmospheric pressure plasma polymerization technique.
11. Stability study of polyacrylic acid films plasma-polymerized on polypropylene substrates at medium pressure
Energy Technology Data Exchange (ETDEWEB)
Morent, Rino, E-mail: [email protected] [Department of Applied Physics, Research Unit Plasma Technology, Faculty of Engineering, Ghent University, Jozef Plateaustraat 22, 9000 Ghent (Belgium); De Geyter, Nathalie [Department of Applied Physics, Research Unit Plasma Technology, Faculty of Engineering, Ghent University, Jozef Plateaustraat 22, 9000 Ghent (Belgium); Trentesaux, Martine; Gengembre, Leon [Unite de Catalyse et Chimie du Solide, UMR CNRS 8181, Universite des Sciences et Technologies de Lille, Bat. C3, Cite Scientifique, 59655 Villeneuve d' Ascq (France); Dubruel, Peter [Department of Organic Chemistry, Polymer Chemistry and Biomaterials Research Group, Faculty of Sciences, Ghent University, Krijgslaan 281, 9000 Ghent (Belgium); Leys, Christophe [Department of Applied Physics, Research Unit Plasma Technology, Faculty of Engineering, Ghent University, Jozef Plateaustraat 22, 9000 Ghent (Belgium); Payen, Edmond [Unite de Catalyse et Chimie du Solide, UMR CNRS 8181, Universite des Sciences et Technologies de Lille, Bat. C3, Cite Scientifique, 59655 Villeneuve d' Ascq (France)
2010-11-01
Plasma polymerization of acrylic acid has become an interesting research subject, since these coatings are expected to be beneficial for biomedical applications due to their high surface density of carboxylic acid functional groups. However, the application of these monomers is counteracted by their low stability in humid environments, since a high stability is a required characteristic for almost any biological application. The present work investigates whether it is possible to obtain stable deposits with a high retention of carboxylic acid functions by performing plasma polymerization on polypropylene substrates with a dielectric barrier discharge operating at medium pressure. In order to obtain coatings with the desired properties, the plasma parameters need to be optimized. Therefore, in this paper, the influence of discharge power and location of the substrate in the discharge chamber is examined in detail. The properties of the deposited films are studied using contact angle measurements, X-ray photoelectron spectroscopy, atomic force microscopy and Fourier transform infrared spectroscopy. Moreover, to determine whether the obtained deposits are soluble in water, the coatings are once again analyzed after rinsing in water. This paper will clearly show that stable COOH-rich surfaces can be obtained at high discharge power and close to the monomer inlet, which might open perspectives for future biomedical applications.
12. Morphological, elemental, and optical characterization of plasma polymerized n-butyl methacrylate thin films
Science.gov (United States)
Nasrin, Rahima; Hossain, Khandker S.; Bhuiyan, A. H.
2018-05-01
Plasma polymerized n-butyl methacrylate (PPnBMA) thin films of varying thicknesses were prepared at room temperature by AC plasma polymerization system using a capacitively coupled parallel plate reactor. Field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), energy-dispersive X-ray (EDX) analysis, and ultraviolet-visible (UV-Vis) spectroscopic investigation have been performed to study the morphological, elemental, and optical properties of the PPnBMA thin films, respectively. The flat and defect-free nature of thin films were confirmed by FESEM and AFM images. With declining plasma power, average roughness and root mean square roughness increase. Allowed direct transition ( E gd) and indirect transition ( E gi) energy gaps were found to be 3.64-3.80 and 3.38-3.45 eV, respectively, for PPnBMA thin films of different thicknesses. Values of E gd as well as E gi increase with the increase of thickness. The extinction coefficient, Urbach energy, and steepness parameter were also determined for these thin films.
13. Antibacterial performance on plasma polymerized heptylamine films loaded with silver nanoparticles
Science.gov (United States)
Lin, Yu-Chun; Lin, Chia-Chun; Lin, Chih-Hao; Wang, Meng-Jiy
2017-01-01
The antibacterial performance of the plasma-polymerized (pp) heptylamine thin films loaded with silver nanoparticles was evaluated against the colonization of Escherichia coli and Staphylococcus aureus. The properties including the thickness and chemical composition of the as deposited HApp films were modulated by adjusting plasma parameters. The acquired results showed that the film thickness was controlled in the range of 20 to 400 nm by adjusting deposition time. The subsequent immersion of the HApp thin films in silver nitrate solutions result in the formation of amine-metal complexes, in which the silver nanoparticles were reduced directly on the matrices to form Ag@HApp. The reduction reaction of silver was facilitated by applying NaBH4 as a reducing agent. The results of physicochemical analyses including morphological analysis and ellipsometry revealed that the silver nanoparticles were successfully reduced on the HApp films, and the amount of reduced silver was closely associated which the thickness of the plasma-polymerized films, the concentration of applied metal ions solutions, and the time of immobilization. Regarding the antibacterial performance, the Ag@HApp films reduced by NaBH4 showed antibacterial abilities of 70.1 and 68.2% against E. coli and S. aureus, respectively.
14. Thin plasma-polymerized layers of hexamethyldisiloxane for humidity sensor development
International Nuclear Information System (INIS)
Guermat, N.; Bellel, A.; Sahli, S.; Segui, Y.; Raynaud, P.
2009-01-01
The response of resistive-type sensors based on thin hexamethyldisiloxane layers to relative humidity (RH) was evaluated. Humidity sensitive layers were plasma polymerized at low frequency glow discharge using a capacitively coupled parallel plate reactor. The sensor design comprises the absorbing layer deposited on clean glass substrate with comb-shape aluminum electrodes (interdigitated structure). The change in electrical impedance of the sensing film was monitored as the device was exposed to humidity. The variation of the plasma-polymerization parameters resulted in different humidity sensing properties which could be correlated to the results of Fourier transform infrared spectroscopy (FTIR). The deposited films exhibited a detectable response to RH ranging from 30 to 95% with low hysteresis, good reproducibility and stability in long-term use. Films with a greater thickness showed a significant decrease in the humidity sensing capability. FTIR analysis revealed the presence of SiH bonding groups, which are frequently linked to the film density. The increase in the plasma discharge power induced also a significant decrease in the diffusion process of water vapor inside the sensitive layer bulk.
15. Investigation of the Effect of Plasma Polymerized Siloxane Coating for Enzyme Immobilization and Microfluidic Device Conception
Directory of Open Access Journals (Sweden)
Kalim Belhacene
2016-12-01
Full Text Available This paper describes the impact of a physical immobilization methodology, using plasma polymerized 1,1,3,3, tetramethyldisiloxane, on the catalytic performance of β-galactosidase from Aspergillus oryzae in a microfluidic device. The β-galactosidase was immobilized by a polymer coating grown by Plasma Enhanced Chemical Vapor Deposition (PEVCD. Combined with a microchannel patterned in the silicone, a microreactor was obtained with which the diffusion through the plasma polymerized layer and the hydrolysis of a synthetic substrate, the resorufin-β-d-galactopyranoside, were studied. A study of the efficiency of the immobilization procedure was investigated after several uses and kinetic parameters of immobilized β-galactosidase were calculated and compared with those of soluble enzyme. Simulation and a modelling approach were also initiated to understand phenomena that influenced enzyme behavior in the physical immobilization method. Thus, the catalytic performances of immobilized enzymes were directly influenced by immobilization conditions and particularly by the diffusion behavior and availability of substrate molecules in the enzyme microenvironment.
16. Synthesis and Characterization of Nanofibrous Polyaniline Thin Film Prepared by Novel Atmospheric Pressure Plasma Polymerization Technique
Directory of Open Access Journals (Sweden)
Choon-Sang Park
2016-01-01
Full Text Available This work presents a study on the preparation of plasma-polymerized aniline (pPANI nanofibers and nanoparticles by an intense plasma cloud type atmospheric pressure plasma jets (iPC-APPJ device with a single bundle of three glass tubes. The nano size polymer was obtained at a sinusoidal wave with a peak value of 8 kV and a frequency of 26 kHz under ambient air. Discharge currents, photo-sensor amplifier, and optical emission spectrometer (OES techniques were used to analyze the plasma produced from the iPC-APPJ device. Field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FT-IR, gas chromatography-mass spectrometry (GC-MS, and gel permeation chromatography (GPC techniques were used to analyze the pPANI. FE-SEM and TEM results show that pPANI has nanofibers, nanoparticles morphology, and polycrystalline characteristics. The FT-IR and GC-MS analysis show the characteristic polyaniline peaks with evidence that some quinone and benzene rings are broken by the discharge energy. GPC results show that pPANI has high molecular weight (Mw, about 533 kDa with 1.9 polydispersity index (PDI. This study contributes to a better understanding on the novel growth process and synthesis of uniform polyaniline nanofibers and nanoparticles with high molecular weights using the simple atmospheric pressure plasma polymerization technique.
17. Wettability, optical properties and molecular structure of plasma polymerized diethylene glycol dimethyl ether
Energy Technology Data Exchange (ETDEWEB)
Azevedo, T C A M; Algatti, M A; Mota, R P; Honda, R Y; Kayama, M E; Kostov, K G; Fernandes, R S [FEG-DFQ-UNESP, Av. Ariberto Pereira da Cunha 333, 12516-410 - Guaratingueta, SP (Brazil); Cruz, N C; Rangel, E C, E-mail: [email protected] [UNESP, Avenida Tres de Marco, 511, 18087-180 Sorocaba, SP (Brazil)
2009-05-01
Modern industry has frequently employed ethylene glycol ethers as monomers in plasma polymerization process to produce different types of coatings. In this work we used a stainless steel plasma reactor to grow thin polymeric films from low pressure RF excited plasma of diethylene glycol dimethyl ether. Plasmas were generated at 5W RF power in the range of 16 Pa to 60 Pa. The molecular structure of plasma polymerized films and their optical properties were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet-Visible Spectroscopy, respectively. The IR spectra show C-H stretching at 3000-2900 cm{sup -1}, C=O stretching at 1730-1650 cm{sup -1}, C-H bending at 1440-1380 cm{sup -1}, C-O and C-O-C stretching at 1200-1000 cm{sup -1}. The refraction index was around 1.5 and the optical gap calculated from absorption coefficient presented value near 3.8 eV. Water contact angle of the films ranged from 40 deg. to 35 deg. with corresponding surface energy from 66 to 73x10{sup -7} J. Because of its favorable optical and hydrophilic characteristics these films can be used in ophthalmic industries as glass lenses coatings.
18. Metal doped fluorocarbon polymer films prepared by plasma polymerization using an RF planar magnetron target
International Nuclear Information System (INIS)
Biederman, H.; Holland, L.
1983-01-01
Fluorocarbon films have been prepared by plasma polymerization of CF 4 using an RF planar magnetron with an aluminium target. More than one order of magnitude higher deposition rate has been achieved in comparison with an r.f. diode system operated under similar conditions of monomer pressure and flow rate and power input. A glow discharge in a CF 4 [25%]-argon[75%] mixture was used to incorporate aluminium from a target electrode into the polymer films. The foregoing mixture and another based on CF 4 [87%]-argon[13%] were used in the RF discharge with a copper target. Some experiments with a gold target and pure CF 4 as the inlet gas were also made. The film structure was examined by SEM and TEM and characteristic micrographs are presented here. The composition of the films was estimated from an EAS study. The sheet resistivity of the metal/polymer film complexes was determined. (orig.)
19. Metal doped polymer films prepared by simultaneous plasma polymerization of tetrafluoromethane and evaporation of gold
Energy Technology Data Exchange (ETDEWEB)
Martinu, L.; Biederman, H. (Karlova Univ., Prague (Czechoslovakia). Fakulta Matematicko-Fyzikalni); Zemek, J. (Ceskoslovenska Akademie Ved, Prague. Fyzikalni Ustav)
The incorporation of gold from an evaporation source during plasma polymerization of tetrafluoromethane CF/sub 4/ in an RF (20 MHz) glow discharge excited by means of a planar magnetron has been investigated. Optical emission spectroscopy was used to monitor the deposition process in situ. The structure of the films was studied by transmission electron microscopy (TEM) observations. The sheet resistance and optical transmission measurements have been performed showing a dramatic influence of gold concentration on the film properties. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) analysis were used for determining the concentration depth profiles through the films. It has been shown that the presence of gold in the layers substantially reduces the fluorine content. The effect of various gold incorporation methods on the film characteristics has been discussed.
20. Preparation of germanium doped plasma polymerized coatings as ICF target ablators
International Nuclear Information System (INIS)
Brusasco, R.M.; Saculla, M.D.; Cook, R.C.
1994-01-01
Targets for Inertial Confinement Fusion (ICF) experiments at the Lawrence Livermore National Laboratory (LLNL) utilize an organic (CH) ablator coating prepared by plasma polymerization. Some of these experiments require a mid-Z dopant in the ablator coating to modify the opacity of the shell. Bromine had been used in the past, but the surface finish of brominated CH degrades rapidly with time upon exposure to air. This paper describes the preparation and characterization of plasma polymer layers containing germanium as a dopant at concentrations of between 1.25 and 2.25 atom percent. The coatings are stable in air and have an rms surface roughness of 7--9 nm (modes 10--1,000) which is similar to that obtained with undoped coatings. High levels of dopant result in cracking of the inner mandrel during target assembly. Possible explanations for the observed cracking behavior will be discussed
1. Decreased Bacterial Attachment and Protein Adsorption to Coatings Produced by Low Enegy Plasma Polymerization
DEFF Research Database (Denmark)
Andersen, T.E.; Kingshott, Peter; Benter, M.
.figure) .and E. coli grown on uncoated silicone compared to PP-PVP coated silicone (right figure). Results from the flow chamber analysis shows PP-PVP to be very good at preventing E. coli colonization during prolonged growth in flow chamber. At this point other surfaces and bacteria remains to be tested...... adsorption and bacteria attachment/colonization. This is emphasized by the fact that long dwelling urinary catheters, which is a typical silicone medical device, causes 5% per day incidence of urinary tract infection [1,2]. A demand therefore exists for surface modifications providing the silicone material......-coated crystals were then treated with one of the plasma polymerized coatings. Adsorption of fibrinogen, human serum albumin or immunoglobulin G was measured using a QCM-D instrument [5] (model E4, Q-Sense AB, Vastra Frolunda, Sweden) using a solution of 50llg/1 protein in PBS buffer. Results and Discussion: Our...
2. Plasma Polymerized Thin Films of Maleic Anhydride and 1,2-methylenedioxybenzene for Improving Adhesion to Carbon Surfaces
DEFF Research Database (Denmark)
Drews, Joanna Maria; Goutianos, Stergios; Kingshott, Peter
2007-01-01
Low power 2-phase AC plasma polymerization has been used to surface modify glassy carbon substrates that are used as an experimental model for carbon fibers in reinforced composites. In order to probe the role of carboxylic acid density on the interfacial adhesion strength a combination...
3. Comparative study of nanocomposites prepared by pulsed and dc sputtering combined with plasma polymerization suitable for photovoltaic device applications
Energy Technology Data Exchange (ETDEWEB)
Hussain, Amreen A. [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Pal, Arup R., E-mail: [email protected] [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Kar, Rajib [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai (India); Bailung, Heremba; Chutia, Joyanti [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Patil, Dinkar S. [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai (India)
2014-12-15
Plasma processing, a single step method for production of large area composite films, is employed to deposit plasma polymerized aniline-Titanium dioxide (PPani-TiO{sub 2}) nanocomposite thin films. The deposition of PPani-TiO{sub 2} nanocomposite films are made using reactive magnetron sputtering and plasma polymerization combined process. This study focuses on the direct comparison between continuous and pulsed dc magnetron sputtering techniques of titanium in combination with rf plasma polymerization of aniline. The deposited PPani-TiO{sub 2} nanocomposite films are characterized and discussed in terms of structural, morphological and optical properties. A self powered hybrid photodetector has been developed by plasma based process. The proposed method provides a new route where the self-assembly of molecules, that is, the spontaneous association of atomic or molecular building blocks under plasma environment, emerge as a successful strategy to form well-defined structural and morphological units of nanometer dimensions. - Highlights: • PPani-TiO{sub 2} nanocomposite by pulsed and dc sputtering with rf plasma polymerization. • In-situ and Ex-situ H{sub 2}SO{sub 4} doping in PPani-TiO{sub 2} nanocomposite. • PPani-TiO{sub 2} nanocomposite based self-powered-hybrid photodetector.
4. Comparative study of nanocomposites prepared by pulsed and dc sputtering combined with plasma polymerization suitable for photovoltaic device applications
International Nuclear Information System (INIS)
Hussain, Amreen A.; Pal, Arup R.; Kar, Rajib; Bailung, Heremba; Chutia, Joyanti; Patil, Dinkar S.
2014-01-01
Plasma processing, a single step method for production of large area composite films, is employed to deposit plasma polymerized aniline-Titanium dioxide (PPani-TiO 2 ) nanocomposite thin films. The deposition of PPani-TiO 2 nanocomposite films are made using reactive magnetron sputtering and plasma polymerization combined process. This study focuses on the direct comparison between continuous and pulsed dc magnetron sputtering techniques of titanium in combination with rf plasma polymerization of aniline. The deposited PPani-TiO 2 nanocomposite films are characterized and discussed in terms of structural, morphological and optical properties. A self powered hybrid photodetector has been developed by plasma based process. The proposed method provides a new route where the self-assembly of molecules, that is, the spontaneous association of atomic or molecular building blocks under plasma environment, emerge as a successful strategy to form well-defined structural and morphological units of nanometer dimensions. - Highlights: • PPani-TiO 2 nanocomposite by pulsed and dc sputtering with rf plasma polymerization. • In-situ and Ex-situ H 2 SO 4 doping in PPani-TiO 2 nanocomposite. • PPani-TiO 2 nanocomposite based self-powered-hybrid photodetector
5. Plasma Polymerization of Acetylene onto silica: and Approach to control the distribution of silica in single elastomers and immiscible blends
NARCIS (Netherlands)
Tiwari, M.; Noordermeer, Jacobus W.M.; Ooij, W.J.; Dierkes, Wilma K.
2008-01-01
Surface modification of silica by acetylene plasma polymerization is applied in order to improve the dispersion in and compatibility with single rubbers and their blends. Silica, used as a reinforcing filler for elastomers, is coated with a polyacetylene (PA) film under vacuum conditions. Water
6. Deposition of stable amine coating onto polycaprolactone nanofibers by low pressure cyclopropylamine plasma polymerization
International Nuclear Information System (INIS)
Manakhov, Anton; Nečas, David; Čechal, Jan; Pavliňák, David; Eliáš, Marek
2015-01-01
Amine-rich films are of high interest for the bio-applications including drug delivery and tissue engineering thanks to their high reactivity allowing the formation of the covalent linkages between biomolecules and a surface. However, the bio-applications of amine-rich films require their good stability in water which is often achieved at large expenses of the amine concentration. Recently, non-toxic cyclopropylamine (CPA) has been applied for the plasma polymerization of films bearing high NH x environment combined with the moderate thickness loss (20%) after water immersion for 48 h. In this work, the amine-rich film with the NH x concentration over 7 at.% was deposited on Si substrates and polycaprolactone nanofiber meshes by using CPA plasma polymerization (pulsed mode) in a vertically oriented stainless steel reactor. The substrates were placed at the radio frequency electrode and the ion bombardment caused by direct-current self-bias was suppressed by using high pressure of 50 Pa. Analysis of samples by scanning electron microscopy did not reveal any cracks in the deposited layer formed during a sample immersion in water. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed a slight oxidation of amine groups in water but the film still contained 5 at.% of NH x (according to the N1s XPS fitting) after the immersion. The rapid oxidation of amine groups was observed during the aging experiment carried out in air at room temperature because FTIR revealed an increase of amide peaks that increased progressively with aging time. However, this oxidation was significantly reduced if the plasma polymer was stored at − 20 °C. Since the films exhibit high amine concentration and very good water stability they have great potential for applications as biocompatible functional coatings. - Highlights: • Cyclopropylamine plasma polymers deposited on polycaprolactone nanofibers • Amine-rich films with high water stability
7. Deposition of stable amine coating onto polycaprolactone nanofibers by low pressure cyclopropylamine plasma polymerization
Energy Technology Data Exchange (ETDEWEB)
Manakhov, Anton [Plasma Technologies, CEITEC — Central European Institute of Technology, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Nečas, David [Plasma Technologies, CEITEC — Central European Institute of Technology, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Čechal, Jan [CEITEC — Central European Institute of Technology, Brno University of Technology, Technická 3058/10, 616 00 Brno (Czech Republic); Pavliňák, David [Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Eliáš, Marek [Plasma Technologies, CEITEC — Central European Institute of Technology, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); and others
2015-04-30
Amine-rich films are of high interest for the bio-applications including drug delivery and tissue engineering thanks to their high reactivity allowing the formation of the covalent linkages between biomolecules and a surface. However, the bio-applications of amine-rich films require their good stability in water which is often achieved at large expenses of the amine concentration. Recently, non-toxic cyclopropylamine (CPA) has been applied for the plasma polymerization of films bearing high NH{sub x} environment combined with the moderate thickness loss (20%) after water immersion for 48 h. In this work, the amine-rich film with the NH{sub x} concentration over 7 at.% was deposited on Si substrates and polycaprolactone nanofiber meshes by using CPA plasma polymerization (pulsed mode) in a vertically oriented stainless steel reactor. The substrates were placed at the radio frequency electrode and the ion bombardment caused by direct-current self-bias was suppressed by using high pressure of 50 Pa. Analysis of samples by scanning electron microscopy did not reveal any cracks in the deposited layer formed during a sample immersion in water. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed a slight oxidation of amine groups in water but the film still contained 5 at.% of NH{sub x} (according to the N1s XPS fitting) after the immersion. The rapid oxidation of amine groups was observed during the aging experiment carried out in air at room temperature because FTIR revealed an increase of amide peaks that increased progressively with aging time. However, this oxidation was significantly reduced if the plasma polymer was stored at − 20 °C. Since the films exhibit high amine concentration and very good water stability they have great potential for applications as biocompatible functional coatings. - Highlights: • Cyclopropylamine plasma polymers deposited on polycaprolactone nanofibers • Amine-rich films with high
8. Polyurethane coating with thin polymer films produced by plasma polymerization of diglyme
International Nuclear Information System (INIS)
Ribeiro, M A; Ramos, A S; Manfredini, M I; Alves, H A; Ramos, E C T; Honda, R Y; Kostov, K G; Lucena, E F; Mota, R P; Algatti, M A; Kayama, M E
2009-01-01
Aqueous-based polyurethane dispersions have been widely utilized as lubricants in textile, shoes, automotive, biomaterial and many other industries because they are less aggressive to surrounding environment. In this work thin films with different thickness were deposited on biocompatible polyurethane by plasma polymerization process using diethylene glycol dimethyl ether (Diglyme) as monomer. Molecular structure of the films was analyzed by Fourier Transform Infrared spectroscopy. The spectra exhibited absorption bands of O-H (3500-3200cm -1 ), C-H (3000-2900cm -1 ), C=O (1730-1650cm -1 ), C-O and C-O-C bonds at 1200-1600cm -1 . The samples wettability was evaluated by measurements of contact angle using different liquids such as water, glycerol, poly-ethane and CMC. The polyurethane surface showed hydrophilic behavior after diglyme plasma-deposition with contact angle dropping from 85 deg. to 22 deg. Scanning Electron Microscopy revealed that diglyme films covered uniformly the polyurethane surfaces ensuring to it a biocompatible characteristic.
9. Metal doped fluorocarbon polymer films prepared by plasma polymerization using an RF planar magnetron target
Energy Technology Data Exchange (ETDEWEB)
Biederman, H.; Holland, L. (Sussex Univ., Brighton (UK). Lab. for Plasma Materials Processing)
1983-07-01
Fluorocarbon films have been prepared by plasma polymerization of CF/sub 4/ using an RF planar magnetron with an aluminium target. More than one order of magnitude higher deposition rate has been achieved in comparison with an R.F. diode system operated under similar conditions of monomer pressure and flow rate and power input. A glow discharge in a CF/sub 4/(25%)-argon(75%) mixture was used to incorporate aluminium from a target electrode into the polymer films. The foregoing mixture and another based on CF/sub 4/(87%)-argon(13%) were used in the RF discharge with a copper target. Some experiments with a gold target and pure CF/sub 4/ as the inlet gas were also made. The film structure was examined by SEM and TEM and characteristic micrographs are presented here. The composition of the films was estimated from an EAS study. The sheet resistivity of the metal/polymer film complexes was determined.
10. Pulsed Plasma Polymerization of Perfluorooctyl Ethylene for Transparent Hydrophobic Thin Coatings
International Nuclear Information System (INIS)
Liu Xiaojun; Wang Lei; Hao Jie; Chu Liqiang
2015-01-01
Herein we report on the deposition of transparent hydrophobic thin coatings by radio frequency plasma polymerization (PP) of perfluorooctyl ethylene (PFOE) in both pulsed and continuous wave (CW) modes. The chemical compositions of the resulting PP-PFOE coatings were confirmed by means of Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The thicknesses and surface morphologies of the coatings were examined using surface plasmon resonance spectroscopy and atomic force microscopy. The surface wetting properties and optical transmittance were measured using a water contact angle goniometer and UV-vis spectroscopy. The FT-IR and XPS data showed that the PP-PFOE coatings deposited in the pulsed mode had a higher retention of CF 2 groups compared to those from the CW mode. While the water contact angle of the freshly deposited PP-PFOE from the pulsed mode showed a decrease from 120 degrees to 111 degrees in the first two days, it then remained almost unchanged up to 45 days. The UV-vis data indicated that a PP-PFOE coating 30.6 nm thick had a light transmittance above 90% in the UV and visible ranges. The deposition rates under various plasma conditions are also discussed. (paper)
11. Plasma-polymerized films providing selective affinity to the polarity of vaporized organic solvents
International Nuclear Information System (INIS)
Akimoto, Takuo; Ikeshita, Yusuke; Terashima, Ryo; Karube, Isao
2009-01-01
Plasma-polymerized films (PPFs) were fabricated as recognition membranes for a vapor-sensing device, and their affinity to vaporized organic solvents was evaluated with surface plasmon resonance. The affinity we intended to create is the selective sorption of the vaporized organic solvents depending on their polarity. For this purpose, acetonitrile, ethylenediamine (EDA), styrene, hexamethyldisiloxane (HMDSO), and hexamethyldisilazane were used to fabricate PPFs. Vaporized methanol, ethanol, and 1-propanol were used as high-polar solvents to be analyzed. Hexane, toluene, and p-xylene were used as low-polar solvents. As a result, the HMDSO-PPF with 97.3 o of contact angle was found to provide affinity to the low-polar solvents. In contrast, the EDA-PPF with 7.1 o of contact angle provided affinity to the high-polar solvents. Observations of the surface morphology of the HMDSO- and EDA-PPFs with a scanning electron microscope revealed that they are composed of nano-scale islands.
12. Grafting of molecularly imprinted polymer to porous polyethylene filtration membranes by plasma polymerization.
Science.gov (United States)
Cowieson, D; Piletska, E; Moczko, E; Piletsky, S
2013-08-01
An application of plasma-induced grafting of polyethylene membranes with a thin layer of molecularly imprinted polymer (MIP) was presented. High-density polyethylene (HDPE) membranes, "Vyon," were used as a substrate for plasma grafting modification. The herbicide atrazine, one of the most popular targets of the molecular imprinting, was chosen as a template. The parameters of the plasma treatment were optimized in order to achieve a good balance between polymerization and ablation processes. Modified HDPE membranes were characterized, and the presence of the grafted polymeric layer was confirmed based on the observed weight gain, pore size measurements, and infrared spectrometry. Since there was no significant change in the porosity of the modified membranes, it was assumed that only a thin layer of the polymer was introduced on the surface. The experiments on the re-binding of the template atrazine to the membranes modified with MIP and blank polymers were performed. HDPE membranes which were grafted with polymer using continuous plasma polymerization demonstrated the best result which was expressed in an imprinted factor equal to 3, suggesting that molecular imprinting was successfully achieved.
13. Polyurethane coating with thin polymer films produced by plasma polymerization of diglyme
Science.gov (United States)
Ribeiro, M. A.; Ramos, A. S.; Manfredini, M. I.; Alves, H. A.; Y Honda, R.; Kostov, K. G.; Lucena, E. F.; Ramos, E. C. T.; Mota, R. P.; Algatti, M. A.; Kayama, M. E.
2009-05-01
Aqueous-based polyurethane dispersions have been widely utilized as lubricants in textile, shoes, automotive, biomaterial and many other industries because they are less aggressive to surrounding environment. In this work thin films with different thickness were deposited on biocompatible polyurethane by plasma polymerization process using diethylene glycol dimethyl ether (Diglyme) as monomer. Molecular structure of the films was analyzed by Fourier Transform Infrared spectroscopy. The spectra exhibited absorption bands of O-H (3500-3200cm-1), C-H (3000-2900cm-1), C=O (1730-1650cm-1), C-O and C-O-C bonds at 1200-1600cm-1. The samples wettability was evaluated by measurements of contact angle using different liquids such as water, glycerol, poly-ethane and CMC. The polyurethane surface showed hydrophilic behavior after diglyme plasma-deposition with contact angle dropping from 85° to 22°. Scanning Electron Microscopy revealed that diglyme films covered uniformly the polyurethane surfaces ensuring to it a biocompatible characteristic.
14. Polyurethane coating with thin polymer films produced by plasma polymerization of diglyme
Energy Technology Data Exchange (ETDEWEB)
Ribeiro, M A; Ramos, A S; Manfredini, M I; Alves, H A; Ramos, E C T [UNIVAP, Sao Jose dos Campos, SP (Brazil); Honda, R Y; Kostov, K G; Lucena, E F; Mota, R P; Algatti, M A; Kayama, M E, E-mail: [email protected] [FEG-DFQ-UNESP, Av. Ariberto Pereira da Cunha 333, 12516-410 - Guaratingueta, SP (Brazil)
2009-05-01
Aqueous-based polyurethane dispersions have been widely utilized as lubricants in textile, shoes, automotive, biomaterial and many other industries because they are less aggressive to surrounding environment. In this work thin films with different thickness were deposited on biocompatible polyurethane by plasma polymerization process using diethylene glycol dimethyl ether (Diglyme) as monomer. Molecular structure of the films was analyzed by Fourier Transform Infrared spectroscopy. The spectra exhibited absorption bands of O-H (3500-3200cm{sup -1}), C-H (3000-2900cm{sup -1}), C=O (1730-1650cm{sup -1}), C-O and C-O-C bonds at 1200-1600cm{sup -1}. The samples wettability was evaluated by measurements of contact angle using different liquids such as water, glycerol, poly-ethane and CMC. The polyurethane surface showed hydrophilic behavior after diglyme plasma-deposition with contact angle dropping from 85 deg. to 22 deg. Scanning Electron Microscopy revealed that diglyme films covered uniformly the polyurethane surfaces ensuring to it a biocompatible characteristic.
15. Plasma-polymerized hexamethyldisilazane treated by nitrogen plasma immersion ion implantation technique
Energy Technology Data Exchange (ETDEWEB)
Honda, R Y; Mota, R P; Batocki, R G S; Santos, D C R; Nicoleti, T; Kostov, K G; Kayama, M E; Algatti, M A [Laboratorio de Plasma, Faculdade de Engenharia, UNESP, Av. Dr Ariberto Pereira da Cunha-333, 12516-410, Guaratingueta, SP (Brazil); Cruz, N C [Laboratorio de Plasmas Tecnologicos, Unidade Diferenciada, UNESP, Av. Tres de Marco-511, 18085-180, Sorocaba, SP (Brazil); Ruggiero, L, E-mail: [email protected] [Faculdade de Ciencias, UNESP, Av. Luis E. Carrijo Coube 14-1, 17033-360, Bauru, SP (Brazil)
2009-05-01
This paper describes the effect of nitrogen Plasma Immersion Ion Implantation (PIII) on chemical structure, refraction index and surface hardness of plasma-polymerized hexamethyldisilazane (PPHMDSN) thin films. Firstly, polymeric films were deposited at 13.56 MHz radiofrequency (RF) Plasma Enhanced Chemical Vapour Deposition (PECVD) and then, were treated by nitrogen PIII from 15 to 60 min. Fourier Transformed Infrared (FTIR) spectroscopy was employed to analyse the molecular structure of the samples, and it revealed that vibrations modes at 3350 cm{sup -1}, 2960 cm{sup -1}, 1650 cm{sup -1}, 1250 cm{sup -1} and 1050 cm{sup -1} were altered by nitrogen PIII. Visible-ultraviolet (vis-UV) spectroscopy was used to evaluate film refractive index and the results showed a slight increase from 1.6 to 1.8 following the implantation time. Nanoindentation revealed a surface hardness rise from 0.5 to 2.3 GPa as PIII treatment time increased. These results indicate nitrogen PIII is very promising in improving optical and mechanical properties of PPHMDSN films.
16. Hydrophobic Coatings on Cotton Obtained by in Situ Plasma Polymerization of a Fluorinated Monomer in Ethanol Solutions.
Science.gov (United States)
Molina, Ricardo; Teixidó, Josep Maria; Kan, Chi-Wai; Jovančić, Petar
2017-02-15
Plasma polymerization using hydrophobic monomers in the gas phase is a well-known technology to generate hydrophobic coatings. However, synthesis of functional hydrophobic coatings using plasma technology in liquids has not yet been accomplished. This work is consequently focused on polymerization of a liquid fluorinated monomer on cotton fabric initiated by atmospheric plasma in a dielectric barrier discharge configuration. Functional hydrophobic coatings on cotton were successfully achieved using in situ atmospheric plasma-initiated polymerization of fluorinated monomer dissolved in ethanol. Gravimetric measurements reveal that the amount of polymer deposited on cotton substrates can be modulated with the concentration of monomer in ethanol solution, and cross-linking reactions occur during plasma polymerization of a fluorinated monomer even without the presence of a cross-linking agent. FTIR and XPS analysis were used to study the chemical composition of hydrophobic coatings and to get insights into the physicochemical processes involved in plasma treatment. SEM analysis reveals that at high monomer concentration, coatings possess a three-dimensional pattern with a characteristic interconnected porous network structure. EDX analysis reveals that plasma polymerization of fluorinated monomers takes place preferentially at the surface of cotton fabric and negligible polymerization takes place inside the cotton fabric. Wetting time measurements confirm the hydrophobicity of cotton coatings obtained although equilibrium moisture content was slightly decreased. Additionally, the abrasion behavior and resistance to washing of plasma-coated cotton has been evaluated.
17. Pyrimidine-pyridine ring interconversion
NARCIS (Netherlands)
Plas, van der H.C.
2003-01-01
This chapter discusses the pyrimidine-to-pyridine ring transformation and pyridine-to-pyrimidine ring transformation. In nucleophile-induced pyrimidine-to-pyridine rearrangements, two types of reactions can be distinguished depending on the structure of the nucleophile: (1) reactions in which the
18. Protonation of pyridine. Vol. 2
Energy Technology Data Exchange (ETDEWEB)
Zahran, N F; Ghoniem, H; Helal, A I [Physics Dept., Nuclear Research Center, AEA., Cairo, (Egypt); Rasheed, N [Nuclear Material Authority, Cairo, (Egypt)
1996-03-01
Field ionization mass spectra of pyridine is measured using 10{mu}m activated wire. protonation of pyridine, is observed as an intense peak in the mass spectra. Charge distribution of pyridine molecule is calculated using the modified neglect of diatomic overlap (MNDO) technique, and consequently proton attachment is proposed to be on the nitrogen atom. Temperature dependence of (M+H){sup +} ion is investigated and discussed. MNDO calculations of the protonated species are done, and the proton affinity of pyridine molecule is estimated. Time dependence of the field ionization process of pyridine and protonated ions are observed and discussed. 5 figs.
19. Decreased material-activation of the complement system using low-energy plasma polymerized poly(vinyl pyrrolidone) coatings
DEFF Research Database (Denmark)
Andersen, T.E.; Kolmos, H.J.; Palarasah, Yaseelan
2011-01-01
In the current study we investigate the activation of blood complement on medical device silicone rubber and present a plasma polymerized vinyl pyrrolidone (ppVP) coating which strongly decreases surface-activation of the blood complement system. We show that uncoated silicone and polystyrene...... surface. The ppVP surface is furthermore characterized physically and chemically using scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR), which indicates preservation of chemical functionality by the applied plasma process. Overall, the pp...
20. Large enhanced dielectric permittivity in polyaniline passivated core-shell nano magnetic iron oxide by plasma polymerization
Energy Technology Data Exchange (ETDEWEB)
Joy, Lija K.; Sooraj, V.; Sethulakshmi, N.; Anantharaman, M. R., E-mail: [email protected] [Department of Physics, Cochin University of Science and Technology, Cochin-682022, Kerala (India); Sajeev, U. S. [Department of Physics, Government College, Kottayam-686613, Kerala (India); Nair, Swapna S. [Department of Physics, School of Mathematical and Physical Sciences, Central University of Kerala, Kasargode-671123, Kerala (India); Narayanan, T. N. [CSIR-Central Electrochemical Research Institute, Karaikkudi-630006, Tamil Nadu (India); Ajayan, P. M. [Department of Material Science and Nano Engineering, Rice University, 6100 Main Street, Houston, Texas 7700 (United States)
2014-03-24
Commercial samples of Magnetite with size ranging from 25–30 nm were coated with polyaniline by using radio frequency plasma polymerization to achieve a core shell structure of magnetic nanoparticle (core)–Polyaniline (shell). High resolution transmission electron microscopy images confirm the core shell architecture of polyaniline coated iron oxide. The dielectric properties of the material were studied before and after plasma treatment. The polymer coated magnetite particles exhibited a large dielectric permittivity with respect to uncoated samples. The dielectric behavior was modeled using a Maxwell–Wagner capacitor model. A plausible mechanism for the enhancement of dielectric permittivity is proposed.
1. pyridine-carboxamide complexes
(2a and 2b) in appreciable yields (L = L1 = N-(furan-2-ylmethyl)-2-pyridine carboxamide and L = L2 = ... able developments in a variety of catalytic transforma- .... Yield: 70–74%. (0.492 g); C22H20CdN6O8S2: Anal. Found: C, 39.13; H,. 2.91; N, 12.37; Cd, 16.64% Calc.: C, 39.26; H, 3.00; N,. Scheme 1. Reaction scheme.
2. Bacterial adhesion on conventional and self-ligating metallic brackets after surface treatment with plasma-polymerized hexamethyldisiloxane
Directory of Open Access Journals (Sweden)
Rogerio Amaral Tupinambá
Full Text Available ABSTRACT Introduction: Plasma-polymerized film deposition was created to modify metallic orthodontic brackets surface properties in order to inhibit bacterial adhesion. Methods: Hexamethyldisiloxane (HMDSO polymer films were deposited on conventional (n = 10 and self-ligating (n = 10 stainless steel orthodontic brackets using the Plasma-Enhanced Chemical Vapor Deposition (PECVD radio frequency technique. The samples were divided into two groups according to the kind of bracket and two subgroups after surface treatment. Scanning Electron Microscopy (SEM analysis was performed to assess the presence of bacterial adhesion over samples surfaces (slot and wings region and film layer integrity. Surface roughness was assessed by Confocal Interferometry (CI and surface wettability, by goniometry. For bacterial adhesion analysis, samples were exposed for 72 hours to a Streptococcus mutans solution for biofilm formation. The values obtained for surface roughness were analyzed using the Mann-Whitney test while biofilm adhesion were assessed by Kruskal-Wallis and SNK test. Results: Significant statistical differences (p 0.05. Conclusion: Plasma-polymerized film deposition was only effective on reducing surface roughness and bacterial adhesion in conventional brackets. It was also noted that conventional brackets showed lower biofilm adhesion than self-ligating brackets despite the absence of film.
3. Bacterial adhesion on conventional and self-ligating metallic brackets after surface treatment with plasma-polymerized hexamethyldisiloxane
Science.gov (United States)
Tupinambá, Rogerio Amaral; Claro, Cristiane Aparecida de Assis; Pereira, Cristiane Aparecida; Nobrega, Celestino José Prudente; Claro, Ana Paula Rosifini Alves
2017-01-01
ABSTRACT Introduction: Plasma-polymerized film deposition was created to modify metallic orthodontic brackets surface properties in order to inhibit bacterial adhesion. Methods: Hexamethyldisiloxane (HMDSO) polymer films were deposited on conventional (n = 10) and self-ligating (n = 10) stainless steel orthodontic brackets using the Plasma-Enhanced Chemical Vapor Deposition (PECVD) radio frequency technique. The samples were divided into two groups according to the kind of bracket and two subgroups after surface treatment. Scanning Electron Microscopy (SEM) analysis was performed to assess the presence of bacterial adhesion over samples surfaces (slot and wings region) and film layer integrity. Surface roughness was assessed by Confocal Interferometry (CI) and surface wettability, by goniometry. For bacterial adhesion analysis, samples were exposed for 72 hours to a Streptococcus mutans solution for biofilm formation. The values obtained for surface roughness were analyzed using the Mann-Whitney test while biofilm adhesion were assessed by Kruskal-Wallis and SNK test. Results: Significant statistical differences (p 0.05). Conclusion: Plasma-polymerized film deposition was only effective on reducing surface roughness and bacterial adhesion in conventional brackets. It was also noted that conventional brackets showed lower biofilm adhesion than self-ligating brackets despite the absence of film. PMID:28902253
4. Bacterial adhesion on conventional and self-ligating metallic brackets after surface treatment with plasma-polymerized hexamethyldisiloxane.
Science.gov (United States)
Tupinambá, Rogerio Amaral; Claro, Cristiane Aparecida de Assis; Pereira, Cristiane Aparecida; Nobrega, Celestino José Prudente; Claro, Ana Paula Rosifini Alves
2017-01-01
Plasma-polymerized film deposition was created to modify metallic orthodontic brackets surface properties in order to inhibit bacterial adhesion. Hexamethyldisiloxane (HMDSO) polymer films were deposited on conventional (n = 10) and self-ligating (n = 10) stainless steel orthodontic brackets using the Plasma-Enhanced Chemical Vapor Deposition (PECVD) radio frequency technique. The samples were divided into two groups according to the kind of bracket and two subgroups after surface treatment. Scanning Electron Microscopy (SEM) analysis was performed to assess the presence of bacterial adhesion over samples surfaces (slot and wings region) and film layer integrity. Surface roughness was assessed by Confocal Interferometry (CI) and surface wettability, by goniometry. For bacterial adhesion analysis, samples were exposed for 72 hours to a Streptococcus mutans solution for biofilm formation. The values obtained for surface roughness were analyzed using the Mann-Whitney test while biofilm adhesion were assessed by Kruskal-Wallis and SNK test. Significant statistical differences (pbrackets after surface treatment and between conventional and self-ligating brackets; no significant statistical differences were observed between self-ligating groups (p> 0.05). Plasma-polymerized film deposition was only effective on reducing surface roughness and bacterial adhesion in conventional brackets. It was also noted that conventional brackets showed lower biofilm adhesion than self-ligating brackets despite the absence of film.
5. Temperature Dependent Electrical Transport in Al/Poly(4-vinyl phenol/p-GaAs Metal-Oxide-Semiconductor by Sol-Gel Spin Coating Method
Directory of Open Access Journals (Sweden)
2016-01-01
Full Text Available Deposition of poly(4-vinyl phenol insulator layer is carried out by applying the spin coating technique onto p-type GaAs substrate so as to create Al/poly(4-vinyl phenol/p-GaAs metal-oxide-semiconductor (MOS structure. Temperature was set to 80–320 K while the current-voltage (I-V characteristics of the structure were examined in the study. Ideality factor (n and barrier height (ϕb values found in the experiment ranged from 3.13 and 0.616 eV (320 K to 11.56 and 0.147 eV (80 K. Comparing the thermionic field emission theory and thermionic emission theory, the temperature dependent ideality factor behavior displayed that thermionic field emission theory is more valid than the latter. The calculated tunneling energy was 96 meV.
6. Synthesis of Lipophilic Antioxidants by a Lipase-B-Catalyzed Addition of Peracids to the Double Bond of 4-Vinyl-2-methoxyphenol.
Science.gov (United States)
Zago, Erika; Durand, Erwann; Barouh, Nathalie; Lecomte, Jérôme; Villeneuve, Pierre; Aouf, Chahinez
2015-10-21
4-Vinyl guaiacol (2) was lipophilized through the electrophilic addition of peracids to its vinylic double bond. Those peracids were formed in situ, by the Candida antarctica lipase-B-assisted perhydrolysis of carboxylic acids ranging from C2 to C18, in hydrogen peroxide solution. The addition of peracids with 4-8 carbons in their alkyl chains led to the formation of two regioisomers, with the prevalence of hydroxyesters bearing a primary free hydroxyl (4c-4e). This prevalence became more pronounced when peracids with longer alkyl chains (C10-C18) were used. In this case, only isomers 4f-4h were formed. The antioxidant activity of the resulting hydroxyesters was assessed by means of the conjugated autoxidizable triene (CAT) assay, and it was found out that the 4-vinyl guaiacol antioxidant activity was significantly increased by grafting alkyl chains with 2-8 carbons.
7. 3-(Pyridin-2-ylcoumarin
Directory of Open Access Journals (Sweden)
Yu-Xia Da
2010-11-01
Full Text Available In the title compound, C14H9NO2, the dihedral angle between the pyridine ring and the lactone ring is 10.40 (3°. The coumarin ring system is nearly planar, with a dihedral angle of 1.40 (2° between the lactone and benzene rings. An intramolecular C—H...O hydrogen bond occurs. In the crystal, inversion dimers linked by pairs of C—H...O interactions occur, generating R22(14 loops.
8. Phosphorus, sulfur and pyridine
OpenAIRE
Schönberger, Stefanie
2013-01-01
The synthesis of distinct neutral or anionic P,S compounds in solution provides a great challenge for chemists. Due to the similarity in the energies of the P–P, P–S and S–S bonds nearly solely a mixture of compounds with different composition and charge is obtained. Our interest focuses on the system consisting of phosphorus, sulfur and pyridine, with the aim of a greater selectivity of P,S compounds in solution. The combination of these three components offers the opportunity...
9. Surface modification of blood-contacting biomaterials by plasma-polymerized superhydrophobic films using hexamethyldisiloxane and tetrafluoromethane as precursors
Energy Technology Data Exchange (ETDEWEB)
Hsiao, Chaio-Ru [Department of Materials Science and Engineering, Feng Chia University, No. 100, Wenhwa Rd., Seatwen District, Taichung City 40724, Taiwan (China); Lin, Cheng-Wei [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, No. 666, Buzih Rd., Beitun District, Taichung City 40601, Taiwan (China); Chou, Chia-Man, E-mail: [email protected] [Department of Surgery, Taichung Veterans General Hospital, No. 1650, Sec. 4, Taiwan Boulevard, Seatwen District, Taichung City 40705, Taiwan (China); Department of Medicine, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Beitou District, Taipei City 11221, Taiwan (China); Chung, Chi-Jen, E-mail: [email protected] [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, No. 666, Buzih Rd., Beitun District, Taichung City 40601, Taiwan (China); He, Ju-Liang [Department of Materials Science and Engineering, Feng Chia University, No. 100, Wenhwa Rd., Seatwen District, Taichung City 40724, Taiwan (China)
2015-08-15
Highlights: • Biomaterials modified by nanoparticle-containing plasma polymerized films. • A superhydrophoic film was obtained, and the properties of the coating were examined. • In vitro blood compatibility tests revealed neither platelet adhesion nor fibrinogen adsorption. • Surface modification technology of medical devices: non-cytotoxic and no blood clot formation. - Abstract: This paper proposes a plasma polymerization system that can be used to modify the surface of the widely used biomaterial, polyurethane (PU), by employing low-cost hexamethyldisiloxane (HMDSO) and tetrafluoromethane (CF{sub 4}) as precursors; this system features a pulsed-dc power supply. Plasma-polymerized HMDSO/CF{sub 4} (pp-HC) with coexisting micro- and nanoscale morphology was obtained as a superhydrophobic coating material by controlling the HMDSO/CF{sub 4} (f{sub H}) monomer flow ratio. The developed surface modification technology can be applied to medical devices, because it is non-cytotoxic and has favorable hemocompatibility, and no blood clots form when the device surface direct contacts. Experimental results reveal that the obtained pp-HC films contained SiO{sub x} nanoparticles randomly dispersed on the micron-scale three-dimensional network film surface. The −CF functional group, −CF{sub 2} bonding, and SiO{sub x} were detected on the film surface. The maximal water contact angle of the pp-HC coating was 161.2°, apparently attributable to the synergistic effect of the coexisting micro- and nanoscale surface morphology featuring a low surface-energy layer. The superhydrophobic and antifouling characteristics of the coating were retained even after it was rubbed 20 times with a steel wool tester. Results of in vitro cytotoxicity, fibrinogen adsorption, and platelet adhesion tests revealed favorable myoblast cell proliferation and the virtual absence of fibrinogen adsorption and platelet adhesion on the pp-HC coated specimens. These quantitative findings imply
10. Heat treatment and aging effect on the structural and optical properties of plasma polymerized 2,6-diethylaniline thin films
International Nuclear Information System (INIS)
Matin, Rummana; Bhuiyan, A.H.
2012-01-01
The monomer, 2,6-diethylaniline has been used to deposit plasma polymerized 2,6-diethylaniline (PPDEA) thin films at room temperature on to glass substrates by a capacitively coupled parallel plate glow discharge reactor. A comparative analysis on the changes of morphological, structural and optical properties of as-deposited, heat treated and aged PPDEA thin films is ascertained. Scanning electron microscopy shows uniform and pinhole free surface of PPDEA thin films and no significant difference in the surface morphology is observed due to heat treatment. Electron dispersive X-ray and Fourier transform infrared spectroscopic investigations indicate some structural rearrangement in PPDEA thin films due to heat treatment. Differential thermal analysis, thermogravimetric analysis and differential thermogravimetric analysis suggest that the PPDEA is thermally stable up to about 580 K. The study on the optical absorption spectra of as-deposited, heat treated and aged PPDEA thin films of different thicknesses lead to the determination of the allowed direct and indirect transition energies ranging from 3.63 to 2.73 and 2.38 to 1.26 eV respectively. Urbach energy, steepness parameter and extinction coefficient are also assessed. It is observed that the optical parameters of as-deposited PPDEA thin films change due to heat treatment and do not change appreciably due to aging. - Highlights: ► Heat treatment and aging effect of plasma polymerized 2,6-diethylaniline thin films. ► The surface morphology of PPDEA is found uniform for all types of sample. ► Heat treatment introduces some elemental and structural rearrangement. ► The thermal stability is found up to about 580 K. ► Optical parameters were changed for heat treatment but not markedly for aging.
11. Gas barrier properties of hydrogenated amorphous carbon films coated on polyethylene terephthalate by plasma polymerization in argon/n-hexane gas mixture
Energy Technology Data Exchange (ETDEWEB)
Polonskyi, Oleksandr; Kylián, Ondřej, E-mail: [email protected]; Petr, Martin; Choukourov, Andrei; Hanuš, Jan; Biederman, Hynek
2013-07-01
Hydrogenated amorphous carbon thin films were deposited by RF plasma polymerization in argon/n-hexane gas mixture on polyethylene terephthalate (PET) foils. It was found that such deposited films may significantly improve the barrier properties of PET. It was demonstrated that the principal parameter that influences barrier properties of such deposited films towards oxygen and water vapor is the density of the coatings. Moreover, it was shown that for achieving good barrier properties it is advantageous to deposit coatings with very low thickness. According to the presented results, optimal thickness of the coating should not be higher than several tens of nm. - Highlights: • a-C:H films were prepared by plasma polymerization in Ar/n-hexane atmosphere. • Barrier properties of coatings are dependent on their density and thickness. • Highest barrier properties were observed for films with thickness 15 nm.
12. In vitro cell culture, platelet adhesion tests and in vivo implant tests of plasma-polymerized para-xylene films
International Nuclear Information System (INIS)
Chou, Chia-Man; Yeh, Chou-Ming; Chung, Chi-Jen; He, Ju-Liang
2013-01-01
Plasma-polymerized para-xylene (PPX) was developed in a previous study by adjusting the process parameters: pulse frequency of the power supply (ω p ) and para-xylene monomer flow rate (f p ). All the obtained PPX films exhibit an amorphous structure and present hydrophobicity (water contact angle ranging from 98.5° to 121.1°), higher film growth rate and good fibroblast cell proliferation. In this study, in vitro tests (fibroblast cell compatibility and platelet adhesion) and an in vivo animal study were performed by using PPX deposited industrial-grade silicone sheets (IGS) and compared with medical-grade silicone ones (MS), which were commonly manufactured into catheters or drainage tubes in clinical use. The results reveal that PPX deposited at high ω p or high f p , in comparison with MS, exhibit better cell proliferation and clearly shows less cell adhesion regardless of ω p and f p . PPX also exhibit a comparatively lower level of platelet adhesion than MS. In the animal study, PPX-coated IGS result in similar local tissue responses at 3, 7 and 28 days (short-term) and 84 days (long-term) after subcutaneous implantation the abdominal wall of rodents compared with respective responses to MS. These results suggest that PPX-coated industrial-grade silicone is one alternative to high cost medical-grade silicone.
13. Surface Modification of Sodium Montmorillonite Nanoclay by Plasma Polymerization and Its Effect on the Properties of Polystyrene Nanocomposites
Directory of Open Access Journals (Sweden)
Rosa Idalia Narro-Céspedes
2018-01-01
Full Text Available Sodium montmorillonite nanoclay (Na+-MMT was modified by plasma polymerization with methyl methacrylate (MMA and styrene (St as monomers and was denominated as Na+-MMT/MMA and Na+-MMT/St, respectively. This plasma modified nanoclay was used as reinforcement for polystyrene (PS nanocomposites that were prepared by melt mixing. Pristine and modified Na+-MMT nanoclay were analyzed by the dispersion in various solvents, Fourier transform infrared spectroscopy (FTIR, thermogravimetric analysis (TGA, and scanning electron microscopy (SEM. The results confirmed a change in hydrophilicity of the modified Na+-MMT, as well as the presence of a polymeric material over its surface. The pristine PS/Na+-MMT and modified PS/Na+-MMT/MMA and PS/Na+-MMT/St nanocomposites were studied with X-ray diffraction (XRD, differential scanning calorimetry (DSC, and TGA, as well as mechanical properties. It was found that the PS/Na+-MMT/St nanocomposites presented better thermal properties and an improvement in Young’s modulus (YM in compared to PS/Na+-MMT/MMA nanocomposites.
14. Wetting, Solubility and Chemical Characteristics of Plasma-Polymerized 1-Isopropyl-4-Methyl-1,4-Cyclohexadiene Thin Films
Directory of Open Access Journals (Sweden)
2014-07-01
Full Text Available Investigations on the wetting, solubility and chemical composition of plasma polymer thin films provide an insight into the feasibility of implementing these polymeric materials in organic electronics, particularly where wet solution processing is involved. In this study, thin films were prepared from 1-isopropyl-4-methyl-1,4-cyclohexadiene (γ-Terpinene using radio frequency (RF plasma polymerization. FTIR showed the polymers to be structurally dissimilar to the original monomer and highly cross-linked, where the loss of original functional groups and the degree of cross-linking increased with deposition power. The polymer surfaces were hydrocarbon-rich, with oxygen present in the form of O–H and C=O functional groups. The oxygen content decreased with deposition power, with films becoming more hydrophobic and, thus, less wettable. The advancing and receding contact angles were investigated, and the water advancing contact angle was found to increase from 63.14° to 73.53° for thin films prepared with an RF power of 10 W to 75 W. The wetting envelopes for the surfaces were constructed to enable the prediction of the surfaces’ wettability for other solvents. The effect of roughness on the wetting behaviour of the films was insignificant. The polymers were determined to resist solubilization in solvents commonly used in the deposition of organic semiconducting layers, including chloroform and chlorobenzene, with higher stability observed in films fabricated at higher RF power.
15. In vitro cell culture, platelet adhesion tests and in vivo implant tests of plasma-polymerized para-xylene films
Energy Technology Data Exchange (ETDEWEB)
Chou, Chia-Man [Department of Surgery, Taichung Veterans General Hospital, Taiwan, ROC (China); National Yang-Ming University, Taipei, Taiwan, ROC (China); Yeh, Chou-Ming, E-mail: [email protected] [Taichung Hospital, Department of Health, Executive Yuan, Taiwan, ROC (China); Chung, Chi-Jen [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taiwan, ROC (China); He, Ju-Liang [Department of Materials Science and Engineering, Feng Chia University, Taiwan, ROC (China)
2013-09-01
Plasma-polymerized para-xylene (PPX) was developed in a previous study by adjusting the process parameters: pulse frequency of the power supply (ω{sub p}) and para-xylene monomer flow rate (f{sub p}). All the obtained PPX films exhibit an amorphous structure and present hydrophobicity (water contact angle ranging from 98.5° to 121.1°), higher film growth rate and good fibroblast cell proliferation. In this study, in vitro tests (fibroblast cell compatibility and platelet adhesion) and an in vivo animal study were performed by using PPX deposited industrial-grade silicone sheets (IGS) and compared with medical-grade silicone ones (MS), which were commonly manufactured into catheters or drainage tubes in clinical use. The results reveal that PPX deposited at high ω{sub p} or high f{sub p}, in comparison with MS, exhibit better cell proliferation and clearly shows less cell adhesion regardless of ω{sub p} and f{sub p}. PPX also exhibit a comparatively lower level of platelet adhesion than MS. In the animal study, PPX-coated IGS result in similar local tissue responses at 3, 7 and 28 days (short-term) and 84 days (long-term) after subcutaneous implantation the abdominal wall of rodents compared with respective responses to MS. These results suggest that PPX-coated industrial-grade silicone is one alternative to high cost medical-grade silicone.
16. A hybrid heterojunction with reverse rectifying characteristics fabricated by magnetron sputtered TiOx and plasma polymerized aniline structure
International Nuclear Information System (INIS)
Sarma, Bimal K; Pal, Arup R; Bailung, Heremba; Chutia, Joyanti
2012-01-01
A TiO x film produced by direct current reactive magnetron sputtering without substrate heating or post-deposition annealing and a plasma polymerized aniline (PPA) structure deposited in the same reactor by a radio-frequency glow discharge without the assistance of a carrier gas are used for the fabrication of a heterojunction. The gas phase discharge is investigated by a Langmuir probe and optical emission spectroscopy. The individual layers and the heterojunction are characterized for structural and optoelectronic properties. PPA has polymer-like structure and texture and is characterized by saturated-unsaturated, branched and crosslinked networks. X-ray photoelectron spectroscopy reveals a slightly reduced TiO x surface, which exhibits near band edge luminescence. The free radicals trapped in PPA readily react with oxygen when exposed to atmosphere. The heterojunction shows reverse rectifying characteristics under dark and ultraviolet (UV) irradiation. The energy levels of TiO x and PPA might exhibit reverse band bending and electrons and holes are accumulated on both sides of the heterojunction. The charge accumulation phenomena at the interface may play a key role in the device performance of a hybrid heterojunction. The current-voltage characteristic of the heterojunction is sensitive to UV light, so the structure may be used for photo-sensing applications. (paper)
17. Preparation and characterization of ethylenediamine and cysteamine plasma polymerized films on piezoelectric quartz crystal surfaces for a biosensor
International Nuclear Information System (INIS)
Mutlu, Selma; Coekeliler, Dilek; Shard, Alex; Goktas, Hilal; Ozansoy, Berna; Mutlu, Mehmet
2008-01-01
This paper describes a method for the modification of quartz crystal surfaces to be used as a transducer in biosensors that allow recognition and quantification of certain biomolecules (antibodies, enzymes, proteins, etc). Quartz crystal sensors were modified by a plasma based electron beam generator in order to detect the level of the toxin histamine within biological liquids (blood, serum) and food (wine, cheese, fish etc.). Cysteamine and ethylenediamine were used as precursors in the plasma. After each modification step, the layers on the quartz crystal were characterized by frequency measurements. Modified surfaces were also characterized by contact angle, X-ray photoelectron spectroscopy and atomic force microscopy to determine the physical and chemical characteristics of the surfaces after each modification. Finally, the performance of the sensors were tested by the response to histamine via frequency shifts. The frequency shifts of the sensors prepared by plasma polymerization of ethylenediamine and cysteamine were approximately 3230 Hz and 5630 Hz, respectively, whereas the frequency change of the unmodified crystal surface was around 575 Hz
18. Influence of the radio-frequency power on the physical and optical properties of plasma polymerized cyclohexane thin films
Energy Technology Data Exchange (ETDEWEB)
Manaa, C., E-mail: [email protected] [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, UFR des Sciences d' Amiens, 33 rue Saint Leu, 80039 Amiens CEDEX 2 (France); Laboratoire des Matériaux Avancés et Phénomènes Quantiques, Université de Tunis El-Manar, Faculté des Sciences de Tunis, Campus universitaire El-Manar, 1068 Tunis (Tunisia); Lejeune, M. [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, UFR des Sciences d' Amiens, 33 rue Saint Leu, 80039 Amiens CEDEX 2 (France); Kouki, F. [Laboratoire des Matériaux Avancés et Phénomènes Quantiques, Université de Tunis El-Manar, Faculté des Sciences de Tunis, Campus universitaire El-Manar, 1068 Tunis (Tunisia); Durand-Drouhin, O. [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, UFR des Sciences d' Amiens, 33 rue Saint Leu, 80039 Amiens CEDEX 2 (France); Bouchriha, H. [Laboratoire des Matériaux Avancés et Phénomènes Quantiques, Université de Tunis El-Manar, Faculté des Sciences de Tunis, Campus universitaire El-Manar, 1068 Tunis (Tunisia); and others
2014-06-02
We investigate in the present study the effects of the radio-frequency plasma power on the opto-electronical properties of the polymeric amorphous hydrogenated carbon thin films deposited at room temperature and different radio-frequency powers by plasma-enhanced chemical vapor deposition method using cyclohexane as precursor. A combination of U.V.–Visible and infrared transmission measurements is applied to characterize the bonding and electronic properties of these films. Some film properties namely surface roughness, contact angle, surface energy, and optical properties are found to be significantly influenced by the radio-frequency power. The changes in these properties are analyzed within the microstructural modifications occurring during growth. - Highlights: • Effects of the radio-frequency power on the optoelectronic properties of thin films • Elaboration of plasma polymerized thin films using cyclohexane as precursor gas • The use of U.V.–Visible-infrared transmission, and optical gap • Study of the surface topography of the films by using Atomic Force microscopy • The use of a capacitively coupled plasma enhanced chemical vapor deposition method.
19. Influence of the radio-frequency power on the physical and optical properties of plasma polymerized cyclohexane thin films
International Nuclear Information System (INIS)
Manaa, C.; Lejeune, M.; Kouki, F.; Durand-Drouhin, O.; Bouchriha, H.
2014-01-01
We investigate in the present study the effects of the radio-frequency plasma power on the opto-electronical properties of the polymeric amorphous hydrogenated carbon thin films deposited at room temperature and different radio-frequency powers by plasma-enhanced chemical vapor deposition method using cyclohexane as precursor. A combination of U.V.–Visible and infrared transmission measurements is applied to characterize the bonding and electronic properties of these films. Some film properties namely surface roughness, contact angle, surface energy, and optical properties are found to be significantly influenced by the radio-frequency power. The changes in these properties are analyzed within the microstructural modifications occurring during growth. - Highlights: • Effects of the radio-frequency power on the optoelectronic properties of thin films • Elaboration of plasma polymerized thin films using cyclohexane as precursor gas • The use of U.V.–Visible-infrared transmission, and optical gap • Study of the surface topography of the films by using Atomic Force microscopy • The use of a capacitively coupled plasma enhanced chemical vapor deposition method
20. 27 CFR 21.122 - Pyridine bases.
Science.gov (United States)
2010-04-01
....122 Pyridine bases. (a) Alkalinity. One ml of pyridine bases dissolved in 10 ml of water is titrated... condenser having a water jacket not less than 400 mm in length. A standardized thermometer is placed in the.... Dissolve 1 ml of pyridine bases in 100 ml of water. (1) Ten ml of this solution are treated with 5 ml of 5...
1. Enhanced corrosion resistance and hemocompatibility of biomedical NiTi alloy by atmospheric-pressure plasma polymerized fluorine-rich coating
Energy Technology Data Exchange (ETDEWEB)
Li, Penghui; Li, Limin [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wang, Wenhao [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Division of Spine Surgery, Department of Orthopaedics and Traumatology, Pokfulam, Hong Kong (China); Jin, Weihong [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Liu, Xiangmei [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan, Hubei 430062 (China); Yeung, Kelvin W.K. [Division of Spine Surgery, Department of Orthopaedics and Traumatology, Pokfulam, Hong Kong (China); Chu, Paul K., E-mail: [email protected] [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)
2014-04-01
Highlights: • Fluoropolymer is deposited on NiTi alloy via atmospheric-pressure plasma polymerization. • The corrosion resistance of NiTi alloy in SBF and DMEM is evidently improved. • The adsorption ratio of albumin to fibrinogen is increased on the coated surface. • The reduced platelet adhesion number indicates better in vitro hemocompatibility. - Abstract: To improve the corrosion resistance and hemocompatibility of biomedical NiTi alloy, hydrophobic polymer coatings are deposited by plasma polymerization in the presence of a fluorine-containing precursor using an atmospheric-pressure plasma jet. This process takes place at a low temperature in air and can be used to deposit fluoropolymer films using organic compounds that cannot be achieved by conventional polymerization techniques. The composition and chemical states of the polymer coatings are characterized by fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The corrosion behavior of the coated and bare NiTi samples is assessed and compared by polarization tests and electrochemical impedance spectroscopy (EIS) in physiological solutions including simulated body fluids (SBF) and Dulbecco's Modified Eagle's medium (DMEM). The corrosion resistance of the coated NiTi alloy is evidently improved. Protein adsorption and platelet adhesion tests reveal that the adsorption ratio of albumin to fibrinogen is increased and the number of adherent platelets on the coating is greatly reduced. The plasma polymerized coating renders NiTi better in vitro hemocompatibility and is promising as a protective and hemocompatible coating on cardiovascular implants.
2. Crumb waste tire rubber surface modification by plasma polymerization of ethanol and its application on oil-well cement
Energy Technology Data Exchange (ETDEWEB)
Xiaowei, Cheng [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu (China); School of Material Science and Engineering, Southwest Petroleum University, Chengdu (China); Sheng, Huang [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu (China); School of Oil and Natural Gas Engineering, Southwest Petroleum University, Chengdu (China); Xiaoyang, Guo, E-mail: [email protected] [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu (China); School of Oil and Natural Gas Engineering, Southwest Petroleum University, Chengdu (China); Wenhui, Duan, E-mail: [email protected] [Department of Civil Engineering, Monash University, Clayton, Melbourne 3800 (Australia)
2017-07-01
Highlights: • The crumb waste tire rubber (WTR) was modified by plasma polymerization of ethanol. • Hydrophilic groups were introduced onto WTR surface and improved its hydrophilia. • The functionalized crumb WTR was applied in oil-well cement. • The mechanical properties of modified oil-well cement were intensively enhanced. - Abstract: Crumb waste tire rubber (WTR) was pretreated by oxygen low temperature plasma (LTP) and modified by LTP polymerization process of ethanol monomer to improve the adhesion property with oil-well cement matrix and the mechanical properties of cement. The surface properties of modified crumb WTR and the mechanical properties and structures of modified oil-well cement were investigated by means of contact angle measurement, dispersion test, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), mechanics performance tests, permeability test and scanning electron microscopy (SEM). It was demonstrated that LTP treatment changed both the surface composition and roughness. The contact angle of pretreated crumb WTR dramatically fell from 122° to 34°, and sample with ethanol LPT polymer film decreased even further to 11°. The ATR-FTIR and XPS analysis results demonstrated that hydrophilic groups, such as –COOH, C–OH, and –CHO, were introduced on the WTR surface. The oxygen atomic percent increased from 8.11% to 14.50% and 24.83%. The mechanical properties, porosity and permeability of raw cement were compared to samples modified by untreated crumb WTR, pretreated crumb WTR and ethanol LTP polymerization treated crumb WTR. It was found that after 28 days, the compressive strength of the samples with the untreated crumb WTR decreased to 80% with respect to raw cement. The tensile strength and flexural strength also had a slight reduction compared with the raw cement. On the contrary, after 28 days, the tensile strength of cement modified by LTP polymerization
3. Crumb waste tire rubber surface modification by plasma polymerization of ethanol and its application on oil-well cement
International Nuclear Information System (INIS)
Xiaowei, Cheng; Sheng, Huang; Xiaoyang, Guo; Wenhui, Duan
2017-01-01
Highlights: • The crumb waste tire rubber (WTR) was modified by plasma polymerization of ethanol. • Hydrophilic groups were introduced onto WTR surface and improved its hydrophilia. • The functionalized crumb WTR was applied in oil-well cement. • The mechanical properties of modified oil-well cement were intensively enhanced. - Abstract: Crumb waste tire rubber (WTR) was pretreated by oxygen low temperature plasma (LTP) and modified by LTP polymerization process of ethanol monomer to improve the adhesion property with oil-well cement matrix and the mechanical properties of cement. The surface properties of modified crumb WTR and the mechanical properties and structures of modified oil-well cement were investigated by means of contact angle measurement, dispersion test, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), mechanics performance tests, permeability test and scanning electron microscopy (SEM). It was demonstrated that LTP treatment changed both the surface composition and roughness. The contact angle of pretreated crumb WTR dramatically fell from 122° to 34°, and sample with ethanol LPT polymer film decreased even further to 11°. The ATR-FTIR and XPS analysis results demonstrated that hydrophilic groups, such as –COOH, C–OH, and –CHO, were introduced on the WTR surface. The oxygen atomic percent increased from 8.11% to 14.50% and 24.83%. The mechanical properties, porosity and permeability of raw cement were compared to samples modified by untreated crumb WTR, pretreated crumb WTR and ethanol LTP polymerization treated crumb WTR. It was found that after 28 days, the compressive strength of the samples with the untreated crumb WTR decreased to 80% with respect to raw cement. The tensile strength and flexural strength also had a slight reduction compared with the raw cement. On the contrary, after 28 days, the tensile strength of cement modified by LTP polymerization
4. High reliable and stable organic field-effect transistor nonvolatile memory with a poly(4-vinyl phenol) charge trapping layer based on a pn-heterojunction active layer
Energy Technology Data Exchange (ETDEWEB)
Xiang, Lanyi; Ying, Jun; Han, Jinhua; Zhang, Letian, E-mail: [email protected], E-mail: [email protected]; Wang, Wei, E-mail: [email protected], E-mail: [email protected] [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)
2016-04-25
In this letter, we demonstrate a high reliable and stable organic field-effect transistor (OFET) based nonvolatile memory (NVM) with a polymer poly(4-vinyl phenol) (PVP) as the charge trapping layer. In the unipolar OFETs, the inreversible shifts of the turn-on voltage (V{sub on}) and severe degradation of the memory window (ΔV{sub on}) at programming (P) and erasing (E) voltages, respectively, block their application in NVMs. The obstacle is overcome by using a pn-heterojunction as the active layer in the OFET memory, which supplied a holes and electrons accumulating channel at the supplied P and E voltages, respectively. Both holes and electrons transferring from the channels to PVP layer and overwriting the trapped charges with an opposite polarity result in the reliable bidirectional shifts of V{sub on} at P and E voltages, respectively. The heterojunction OFET exhibits excellent nonvolatile memory characteristics, with a large ΔV{sub on} of 8.5 V, desired reading (R) voltage at 0 V, reliable P/R/E/R dynamic endurance over 100 cycles and a long retention time over 10 years.
5. Acid-base strengths in pyridine
NARCIS (Netherlands)
Bos, M.; Dahmen, E.A.M.F.
1971-01-01
Although pyridine is a solvent with a low dielectric constant, spectrophotometric determinations show simple dissociation without ion pairs as intermediates for some sulfonphthaleins and polynitrophenols in pyridine. The salts of a number of amines and hydrochloric acid, perchloric acid and picric
6. Fine structures and magnetic properties of FeCo granular thin films with plasma polymerized (C4F8) n matrix
International Nuclear Information System (INIS)
Kakizaki, K.; Yasoshima, S.; Choi, K.-K.; Kamishima, K.; Hiratsuka, N.
2007-01-01
In this paper a method for polymerization of fluorocarbon gas in argon plasma to obtain a novel granular structure was reported. We prepared granular films where FeCo fine particles were distributed in plasma-polymerized fluorocarbon matrix by a facing-targets RF magnetron sputtering method, and investigated the correlation between their structures and magnetic properties. The magnetization of the films prepared with the partial pressure of fluorocarbon gas between 0 and 1.0 mTorr decreased linearly, because the FeCo content in a unit volume of a film decreased when a polymerized material was used as the matrix. However, the coercivity of the films decreased drastically with increasing the partial pressure of fluorocarbon gas above 0.4 mTorr. This is because the magnetic anisotropy of FeCo particles is decreased by the decrease of grain size. It was confirmed by a TEM observation that the FeCo-(C 4 F 8 ) n films had the granular structure which was constituted by the very fine FeCo particles and the plasma-polymerized fluorocarbon matrix. For the film deposited at the partial pressure of fluorocarbon gas of 0.4 mTorr, the size of FeCo magnetic particles is about 20 nm. On the other hand, the size of FeCo particles is decreased to about 8 nm when the film deposited at the partial pressure of fluorocarbon gas of 0.8 mTorr and its distribution is small
7. The Contrasting Alkylations of 4-(Dimethylaminomethyl)pyridine and 4-(Dimethylamino)pyridine: An Organic Chemistry Experiment
Science.gov (United States)
Jantzi, Kevin L.; Wiltrakis, Susan; Wolf, Lauren; Weber, Anna; Cardinal, Josh; Krieter, Katie
2011-01-01
A critical factor for the increased nucleophilicity of the pyridine nitrogen in 4-(dimethylamino)pyridine (DMAP) is electron donation via resonance from the amino group into the aromatic ring that increases electron density on the pyridine nitrogen. To explore how important this resonance effect is, 4-(dimethylaminomethyl)pyridine (DMAMP) was…
8. Effects of plasma polymerized para-xylene intermediate layers on characteristics of flexible organic light emitting diodes fabricated on polyethylene terephthalate substrates
International Nuclear Information System (INIS)
Sohn, Sunyoung; Kim, Kyuhyung; Kho, Samil; Jung, Donggeun; Boo, Jin-hyo
2008-01-01
Characteristics of flexible organic light emitting diodes (FOLEDs) with the plasma polymerized para-xylene (PPpX) intermediate layer were investigated. For the purpose of reducing moisture permeation through plastic substrates, a PPpX intermediate layer was inserted between FOLEDs and the plastic substrates. As the concentration of C-H bonding in the PPpX film deposited at 25 deg. C was increased, PPpX films showed increased transmittance. Surface morphologies of polyethylene terephthalate (PET) covered with the PPpX intermediate layer were improved compared to PET without PPpX on it. Due to the highly cross-linked network structure in the plasma polymer film, water vapor permeability of PET substrates with the PPpX intermediate layer of 75 nm was decreased compared to PET substrates without PPpX on it. FOLEDs with the PPpX intermediate layer showed improved optical and electrical characteristics as well as lifetimes than FOLEDs without the PPpX intermediate layer
9. Visible photoluminescence from plasma-polymerized-organosilicone thin films deposited from HMDSO/O2 induced remote plasma: effect of oxygen fraction
Science.gov (United States)
2008-09-01
Visible photoluminescence (PL) from thin films deposited on silicon wafers by remote plasma polymerization of the hexamethyledisiloxane (HMDSO)/O2 mixture in a radio-frequency hollow cathode discharge reactor has been investigated as a function of different oxygen fractions ( \\chi _{O_2 } =0 , 0.38, 0.61, 0.76 and 0.9). At room temperature, the film deposited at \\chi _{O_2 } =0 exhibits a strong, broad PL band peak centred at around 537.6 nm. A blue shift and a considerable decrease (~one order) in the intensity of the PL peak are observed after the addition of oxygen. Furthermore, in contrast to the film deposited from pure HMDSO, the low temperature (15 K) PL spectra of the film deposited from different HMDSO/O2 mixtures exhibit two separated 'green-blue' and 'yellow-green' PL peaks. The PL behaviour of the deposited films is correlated with their structural and morphological properties, investigated by using Fourier transform infrared, atomic force microscope and contact angle techniques. In addition, it is found from spectrophotometry measurements that the deposited films have relatively low absorption coefficients (in the range 100-500 cm-1) in the spectral range of their PL emission, attractive for possible integrated optics devices.
10. Visible photoluminescence from plasma-polymerized-organosilicone thin films deposited from HMDSO/O2 induced remote plasma: effect of oxygen fraction
International Nuclear Information System (INIS)
2009-01-01
Visible photoluminescence (PL) from thin films deposited on silicon wafers by remote plasma polymerization of the hexamethyldisiloxane (HMDSO)/O 2 mixture in a radio-frequency hollow cathode discharge reactor has been investigated as a function of different oxygen fractions (χ0 2 0.38, 0.61, 0.76 and 0.9). At room temperature, the film deposited at exhibits a strong, broad PL band peak centred at around 537.6 nm. A blue shift and a considerable decrease (∼one order) in the intensity of the PL peak are observed after the addition of oxygen. Furthermore, in contrast to the film deposited from pure HMDSO, the low temperature (15 K) PL spectra of the film deposited from different HMDSO/O 2 mixtures exhibit two separated green-blue and yellow-green PL peaks. The PL behaviour of the deposited films is correlated with their structural and morphological properties, investigated by using Fourier transform infrared, atomic force microscope and contact angle techniques. In addition, it is found from spectrophotometry measurements that the deposited films have relatively low absorption coefficients (in the range 100-500 cm -1 ) in the spectral range of their PL emission, attractive for possible integrated optics devices. (authors)
11. Visible photoluminescence from plasma-polymerized-organosilicone thin films deposited from HMDSO/O{sub 2} induced remote plasma: effect of oxygen fraction
Energy Technology Data Exchange (ETDEWEB)
Naddaf, M; Saloum, S [Department of Physics, Atomic Energy Commission of Syria (AECS), PO Box 6091 Damascus (Syrian Arab Republic)], E-mail: [email protected]
2008-09-07
Visible photoluminescence (PL) from thin films deposited on silicon wafers by remote plasma polymerization of the hexamethyledisiloxane (HMDSO)/O{sub 2} mixture in a radio-frequency hollow cathode discharge reactor has been investigated as a function of different oxygen fractions ({chi}{sub O{sub 2}}=0, 0.38, 0.61, 0.76 and 0.9). At room temperature, the film deposited at ({chi}{sub O{sub 2}}=0 exhibits a strong, broad PL band peak centred at around 537.6 nm. A blue shift and a considerable decrease ({approx}one order) in the intensity of the PL peak are observed after the addition of oxygen. Furthermore, in contrast to the film deposited from pure HMDSO, the low temperature (15 K) PL spectra of the film deposited from different HMDSO/O{sub 2} mixtures exhibit two separated 'green-blue' and 'yellow-green' PL peaks. The PL behaviour of the deposited films is correlated with their structural and morphological properties, investigated by using Fourier transform infrared, atomic force microscope and contact angle techniques. In addition, it is found from spectrophotometry measurements that the deposited films have relatively low absorption coefficients (in the range 100-500 cm{sup -1}) in the spectral range of their PL emission, attractive for possible integrated optics devices.
12. Visible photoluminescence from plasma-polymerized-organosilicone thin films deposited from HMDSO/O2 induced remote plasma: effect of oxygen fraction
International Nuclear Information System (INIS)
2008-01-01
Visible photoluminescence (PL) from thin films deposited on silicon wafers by remote plasma polymerization of the hexamethyledisiloxane (HMDSO)/O 2 mixture in a radio-frequency hollow cathode discharge reactor has been investigated as a function of different oxygen fractions (χ O 2 =0, 0.38, 0.61, 0.76 and 0.9). At room temperature, the film deposited at (χ O 2 =0 exhibits a strong, broad PL band peak centred at around 537.6 nm. A blue shift and a considerable decrease (∼one order) in the intensity of the PL peak are observed after the addition of oxygen. Furthermore, in contrast to the film deposited from pure HMDSO, the low temperature (15 K) PL spectra of the film deposited from different HMDSO/O 2 mixtures exhibit two separated 'green-blue' and 'yellow-green' PL peaks. The PL behaviour of the deposited films is correlated with their structural and morphological properties, investigated by using Fourier transform infrared, atomic force microscope and contact angle techniques. In addition, it is found from spectrophotometry measurements that the deposited films have relatively low absorption coefficients (in the range 100-500 cm -1 ) in the spectral range of their PL emission, attractive for possible integrated optics devices
13. Pyridine-induced Dimensionality Change in Hybrid Perovskite Nanocrystals
KAUST Repository
Ahmed, Ghada H.; Yin, Jun; Bose, Riya; Sinatra, Lutfan; Alarousu, Erkki; Yengel, Emre; AlYami, Noktan; Saidaminov, Makhsud I.; Zhang, Yuhai; Hedhili, Mohamed N.; Bakr, Osman; Bredas, Jean-Luc; Mohammed, Omar F.
2017-01-01
of pyridine during the synthesis of methylammonium lead bromide (MAPbBr) perovskite nanocrystals can transform three-dimensional (3D) cubes into two-dimensional (2D) nanostructures. Density functional theory (DFT) calculations show that pyridine preferentially
14. Electrocatalytic oxidations of pyridine derivatives using Ru(IV) poly pyridine complex
International Nuclear Information System (INIS)
Oliveira, S.M. de.
1989-01-01
The oxidation reactions electro catalysed by bi pyridine oxo tri pyridine ruthenium perchlorate metallic complex from selected organic substrates are studied. The obtained results are compared with forecasting results showing the coherence of suggested mechanism. The substrates 2-, 2- and 4- picolines with its respective 1-oxides and 1,2 -; 1,3 - and 1,4 - dimethyl pyridine chloride salts were analysed. The oxidation of toluene as reference substrate was also studied and the mass spectra of oxidation products were interpreted. (M.C.K.)
15. 2-Aminobenzoic acid–4-(pyridin-4-yldisulfanyl)pyridine (1/1)
OpenAIRE
Hadi D. Arman; Trupta Kaulgud; Edward R. T. Tiekink
2011-01-01
The title 1:1 co-crystal, C7H7NO2·C10H8N2S2, features a highly twisted 4-(pyridin-4-yldisulfanyl)pyridine molecule [dihedral angle between the pyridine rings = 89.06 (10)°]. A small twist is evident in the 2-aminobenzoic acid molecule, with the C—C—C—O torsion angle being −7.7 (3)°. An N—H...O hydrogen bond occurs in the 2-aminobenzoic acid molecule. In the crystal, molecules are linked by O&#...
16. Riboflavin Production during Growth of Micrococcus luteus on Pyridine
OpenAIRE
Sims, Gerald K.; O'Loughlin, Edward J.
1992-01-01
Micrococcus luteus produced 29 μM riboflavin during growth on 6.5 mM pyridine but not during growth on other substrates. On the basis of the results of radiolabelling studies, riboflavin was not directly synthesized from pyridine. Pyridine may interfere with riboflavin biosynthesis or elicit a general stress response in M. luteus.
17. Study of the adhesive properties versus stability/aging of hernia repair meshes after deposition of RF activated plasma polymerized acrylic acid coating
International Nuclear Information System (INIS)
Rivolo, Paola; Nisticò, Roberto; Barone, Fabrizio; Faga, Maria Giulia; Duraccio, Donatella; Martorana, Selanna; Ricciardi, Serena; Magnacca, Giuliana
2016-01-01
In order to confer adhesive properties to commercial polypropylene (PP) meshes, a surface plasma-induced deposition of poly-(acrylic acid) (PPAA) is performed. Once biomaterials were functionalized, different post-deposition treatments (i.e. water washing and/or thermal treatments) were investigated with the aim of monitoring the coating degradation (and therefore the loss of adhesion) after 3 months of aging in both humid/oxidant (air) and inert (nitrogen) atmospheres. A wide physicochemical characterization was carried out in order to evaluate the functionalization effectiveness and the adhesive coating homogeneity by means of static water drop shape analysis and several spectroscopies (namely, FTIR, UV–Visible and X-ray Photoemission Spectroscopy). The modification of the adhesion properties after post-deposition treatments as well as aging under different storage atmospheres were investigated by means of Atomic Force Microscopy (AFM) used in Force/Distance (F/D) mode. This technique confirms itself as a powerful tool for unveiling the surface adhesion capacity as well as the homogeneity of the functional coatings along the fibers. Results obtained evidenced that post-deposition treatments are mandatory in order to remove all oligomers produced during the plasma-treatment, whereas aging tests evidenced that these devices can be simply stored in presence of air for at least three months without a meaningful degradation of the original properties. - Highlights: • Plasma polymerized surface functionalization of hernia-repair meshes was used to confer adhesive properties. • The stability of the adhesive coating was verified under different post-deposition conditions. • The use of AFM in F/D mode was selected to monitor the coating degradation.
18. Study of the adhesive properties versus stability/aging of hernia repair meshes after deposition of RF activated plasma polymerized acrylic acid coating
Energy Technology Data Exchange (ETDEWEB)
Rivolo, Paola [Politecnico di Torino, Department of Applied Science and Technology, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Nisticò, Roberto, E-mail: [email protected] [University of Torino, Department of Chemistry and NIS Centre, Via P. Giuria 7, 10125 Torino (Italy); Barone, Fabrizio [University of Torino, Department of Chemistry and NIS Centre, Via P. Giuria 7, 10125 Torino (Italy); Faga, Maria Giulia; Duraccio, Donatella [CNR-IMAMOTER, Strada delle Cacce 73, 10135 Torino (Italy); Martorana, Selanna [Herniamesh S.r.l., Via F.lli Meliga 1/C, 10034 Chivasso (Italy); Ricciardi, Serena [Politecnico di Torino, Department of Applied Science and Technology, C.so Duca degli Abruzzi 24, 10129 Torino (Italy); Magnacca, Giuliana [University of Torino, Department of Chemistry and NIS Centre, Via P. Giuria 7, 10125 Torino (Italy)
2016-08-01
In order to confer adhesive properties to commercial polypropylene (PP) meshes, a surface plasma-induced deposition of poly-(acrylic acid) (PPAA) is performed. Once biomaterials were functionalized, different post-deposition treatments (i.e. water washing and/or thermal treatments) were investigated with the aim of monitoring the coating degradation (and therefore the loss of adhesion) after 3 months of aging in both humid/oxidant (air) and inert (nitrogen) atmospheres. A wide physicochemical characterization was carried out in order to evaluate the functionalization effectiveness and the adhesive coating homogeneity by means of static water drop shape analysis and several spectroscopies (namely, FTIR, UV–Visible and X-ray Photoemission Spectroscopy). The modification of the adhesion properties after post-deposition treatments as well as aging under different storage atmospheres were investigated by means of Atomic Force Microscopy (AFM) used in Force/Distance (F/D) mode. This technique confirms itself as a powerful tool for unveiling the surface adhesion capacity as well as the homogeneity of the functional coatings along the fibers. Results obtained evidenced that post-deposition treatments are mandatory in order to remove all oligomers produced during the plasma-treatment, whereas aging tests evidenced that these devices can be simply stored in presence of air for at least three months without a meaningful degradation of the original properties. - Highlights: • Plasma polymerized surface functionalization of hernia-repair meshes was used to confer adhesive properties. • The stability of the adhesive coating was verified under different post-deposition conditions. • The use of AFM in F/D mode was selected to monitor the coating degradation.
19. Thermometric titration of acids in pyridine.
Science.gov (United States)
Vidal, R; Mukherjee, L M
1974-04-01
Thermometric titration of HClO(4), HI, HNO(3), HBr, picric acid o-nitrobenzoic acid, 2,4- and 2,5-dinitrophenol, acetic acid and benzoic acid have been attempted in pyridine as solvent, using 1,3-diphenylguanidine as the base. Except in the case of 2,5-dinitrophenol, acetic acid and benzoic acid, the results are, in general, reasonably satisfactory. The approximate molar heats of neutralization have been calculated.
20. Hydrophobicity attainment and wear resistance enhancement on glass substrates by atmospheric plasma-polymerization of mixtures of an aminosilane and a fluorocarbon
Energy Technology Data Exchange (ETDEWEB)
Múgica-Vidal, Rodolfo, E-mail: [email protected] [Department of Mechanical Engineering, University of La Rioja, c/ Luis de Ulloa 20, 26004, Logroño, La Rioja (Spain); Alba-Elías, Fernando, E-mail: [email protected] [Department of Mechanical Engineering, University of La Rioja, c/ Luis de Ulloa 20, 26004, Logroño, La Rioja (Spain); Sainz-García, Elisa, E-mail: [email protected] [Department of Mechanical Engineering, University of La Rioja, c/ Luis de Ulloa 20, 26004, Logroño, La Rioja (Spain); Pantoja-Ruiz, Mariola, E-mail: [email protected] [Materials Science and Engineering Department, IAAB, Materials Performance Group, University Carlos III of Madrid, Av. Universidad 30, 28911, Leganés, Madrid (Spain)
2015-08-30
Graphical abstract: - Highlights: • APTES and PFH were used to coat glass by non-thermal atmospheric jet plasma. • A mixture of 75% of APTES and 25% PFH produced the best sample of this work. • Hydrophobicity was achieved by changes in surface morphology and chemistry. • Wear resistance was enhanced by the formation of siloxane groups. - Abstract: Mixtures of different proportions of two liquid precursors were subjected to plasma-polymerization by a non-thermal atmospheric jet plasma system in a search for a coating that achieves a hydrophobic character on a glass substrate and enhances its wear resistance. 1-Perfluorohexene (PFH) was chosen as a low-surface-energy precursor to promote a hydrophobic character. Aminopropyltriethoxysilane (APTES) was chosen for its contribution to the improvement of wear resistance by the formation of siloxane bonds. The objective of this work was to determine which of the precursors’ mixtures that were tested provides the coating with the most balanced enhancement of both hydrophobicity and wear resistance, given that coatings deposited with fluorocarbon-based precursors such as PFH are usually low in resistance to wear and coatings deposited with APTES are generally hydrophilic. The coatings obtained were analyzed by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier Transform Infra-Red (FTIR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), static Water Contact Angle (WCA) measurements, tribological ball-on-disc tests and contact profilometry. A relationship between the achievement of a hydrophobic character and the modifications to roughness and surface morphology and the incorporation of fluorocarbon groups in the surface chemistry was observed. Also, it was seen that the wear resistance was influenced by the SiOSi content of the coatings. In turn, the SiOSi content appears to be directly related to the percentage of APTES used in the mixture of precursors. The best conjunction of
1. UV-VIS-spectroscopical investigations of the green solutions of nitrogen triiodide-1-pyridine in pyridine
International Nuclear Information System (INIS)
Kerbachi, R.; Minkwitz, R.; Engelhardt, U.
1984-01-01
Solid, crystalline nitrogen triiodide-1-pyridine has a polymeric structure similar to that of nitrogen triiodide-1-ammonia consisting of NI 4 tetrahedra linked to chains by common vertices. The solubility of both compounds in liquid ammonia is accomplished by a degradation of the chains involving protolysis equilibria with monoiodamine. UV-VIS-spectra of the green solutions of NI 3 pyridine in the aprotic solvent pyridine between -30 and -16 0 C and Raman-spectra of these solutions at -30 0 C or quenched with liquid nitrogen at -196 0 C show, that the chains are retained here at least to some extent. The solutions are instable even at low temperatures and decompose in a first order reaction yielding nitrogen and iodine. The halflife period at -16 0 C is 5 hours, at -30 0 C 20 hours. (author)
2. Pyridine-Based Conjugated Polymers: Photophysical Properties and Light- Emitting Diodes
National Research Council Canada - National Science Library
Epstein, A
1997-01-01
We study the photophysical properties of the pyridine-based polymers poly (p-pyridyl vinylene) (PPyV) and poly (p-pyridine) (PPy). The primary photoexcitations in the pyridine-based polymers are singlet excitons...
3. 2-[(Pyridin-3-ylaminomethyl]phenol
Directory of Open Access Journals (Sweden)
Jing Xu
2011-12-01
Full Text Available In the title compound, C12H12N2O, the aromatic rings at either ends of the –CH2–NH– link are twisted by 68.79 (7°. In the crystal, the hydroxy substituent is a hydrogen-bond donor to the N atom of the pyridine ring of an adjacent molecule, and the hydrogen bond generates a chain along the b axis; it is also a hydrogen-bond acceptor to the amino group of another adjacent molecule. The two hydrogen bonds lead to the formation of a layer structure.
4. Microwave Determination of the Structure of Pyridine
Energy Technology Data Exchange (ETDEWEB)
Bak, B.; Hansen, L.; Rastrup-Andersen, J. [Chemical Laboratory of the University of Copenhagen, Copenhagen (Denmark)
1954-12-15
2‐, 3‐, and 4‐mono‐deutero‐pyridine have been prepared and the microwave spectra recorded. For each of the isotopic species 11—12 transitions (Q‐ and R‐branch lines) were localized, a number of which could be identified by their Stark effect. For all three species rotational constants of high precision were calculated. The material so provided in connection with known rotational constants for ordinary pyridine is insufficient for a complete determination of the ten geometrical parameters of the molecule. Seven models with a choice of C – H distances close to the correct value (1.075‐1.085 A) were considered one of which was shown to be consistent with electron‐diffraction work and current valence theory. In this model d(N – C(2)) = 1.340±0.005; d(C(2) – C(3)) = 1.390±0.005; d(C(3) – C(4)) = 1.400±0.005 A. The valence angles in the aromatic ring (starting with the C(6) – N – C(2) angle) are: 116° 42′; 124° 00′; 118° 36′; 118° 06′.
5. Preparation of nucleoside-pyridine hybrids and pyridine attached acylureas from an unexpected uracil ring-opening and pyridine ring-forming sequence
Institute of Scientific and Technical Information of China (English)
Xue Sen Fan; Xia Wang; Xin Ying Zhang; Dong Feng; Ying Ying Qu
2009-01-01
Novel pyrimidine nucleoside-3,5-dicyanopyridine hybrids (4) or pyridine attached acylureas (5) were selectively and efficiently prepared from the reaction of 2'-deoxyuridin-5-yl-methylene malonortitrile (1), malononitrile (2) and thiophenol (3) or from an unexpected uracil ring-opening and pyridine ring-forming sequence via the reaction of 1 and 3. It is the first time such a sequence has ever been reported.
6. 2-Aminobenzoic acid–4-[2-(pyridin-4-ylethyl]pyridine (2/1
Directory of Open Access Journals (Sweden)
2013-11-01
Full Text Available The asymmetric unit of the title co-crystal, C12H12N2·2C7H7NO2, comprises a centrosymmetric 4-[2-(pyridin-4-ylethyl]pyridine molecule and a 2-aminobenzoic acid molecule in a general position. The acid has a small twist between the carboxylic acid residue and the ring [dihedral angle = 7.13 (6°] despite the presence of an intramolecular N—H...O(carbonyl hydrogen bond. Three-molecule aggregates are formed via O—H...N(pyridyl hydrogen bonds, and these are connected into supramolecular layers in the bc plane by N—H...O(carbonyl hydrogen bonds and π–π interactions between pyridine and benzene rings [inter-centroid distance = 3.6332 (9 Å]. Layers are connected along the a axis by weak π–π interactions between benzene rings [3.9577 (10 Å].
7. Rapid anaerobic mineralization of pyridine in a subsurface sediment inoculated with a pyridine-degrading Alcaligenes sp
Energy Technology Data Exchange (ETDEWEB)
Ronen, Z; Bollag, J M [Pennsylvania State Univ., University Park, PA (United States). Lab. of Soil Biochemistry
1992-05-01
A denitrifying bacterium capable of pyridine mineralization under anaerobic conditions was isolated from polluted soil. The bacterium, identified as Alcaligenes sp., was used in inoculation experiments. A subsurface sediment from a polluted site was amended with 10 {mu}g/g {sup 14}C-labeled pyridine, and 250 {mu}g/g nitrate, and then inoculated with the bacterium at an inoculum size of 4.5x10{sup 7} cells/g. After 44 h incubation at 28deg C under anaerobic conditions, 67% of the radioactivity was recovered as {sup 14}CO{sub 2}: 2% was extracted with 50% methanol, and 24% was recovered by combustion of the sediment. Analysis of the methanol extract revealed that no pyridine could be detected in the inoculated sediment. In contrast, mineralization of pyridine by the native microflora in the sediment occurred much more slowly: After 7 days of incubation only 10% of the added radioactivity was recovered as {sup 14}CO{sub 2}. At an inoculum size of 2x10{sup 3} cells/g pyridine mineralization was not as effective as at an inoculum size of 2x10{sup 7} cells/g. It is presumed that suppression of the introduced bacteria by the native microflora of the sediment prevents degradation at a low inoculum size. Amending the sediment with nitrate and phosphate improved pyridine mineralization by the introduced bacterium. These findings demonstrate the feasibility of using soil inoculation anaerobically for the bioremediation of pyridine-polluted soils. (orig.).
8. Functional conjugated pyridines via main-group element tuning.
Science.gov (United States)
Stolar, Monika; Baumgartner, Thomas
2018-03-29
Pyridine-based materials have seen widespread attention for the development of n-type organic materials. In recent years, the incorporation of main-group elements has also explored significant advantages for the development and tunability of organic conjugated materials. The unique chemical and electronic structure of main-group elements has led to several enhancements in conventional organic materials. This Feature article highlights recent main-group based pyridine materials by discussing property enhancements and application in organic electronics.
9. Synthesis of pyridines over zeolites in gas phase
Czech Academy of Sciences Publication Activity Database
Slobodník, M.; Hronec, M.; Cvengrošová, Z.; Voláková, Martina; Čejka, Jiří
2007-01-01
Roč. 72, 5-6 (2007), s. 618-628 ISSN 0010-0765 Grant - others:VEGA(XE) 1/2459/05 Institutional research plan: CEZ:AV0Z40400503 Source of funding: R - rámcový projekt EK Keywords : pyridine * pyridine bases * ZSM-5 * ethanol Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.879, year: 2007
10. Pyridinium bis(pyridine-κNtetrakis(thiocyanato-κNferrate(III
Directory of Open Access Journals (Sweden)
Sergii I. Shylin
2013-06-01
Full Text Available In the title compound, (C5H6N[Fe(NCS4(C5H5N2], the FeIII ion is coordinated by four thiocyanate N atoms and two pyridine N atoms in a trans arrangement, forming an FeN6 polyhedron with a slightly distorted octahedral geometry. Charge balance is achieved by one pyridinium cation bound to the complex anion via N—H...S hydrogen bonding. The asymmetric unit consists of one FeIII cation, four thiocyanate anions, two coordinated pyridine molecules and one pyridinium cation. The structure exhibits π–π interactions between pyridine rings [centroid–centroid distances = 3.7267 (2, 3.7811 (2 and 3.8924 (2 Å]. The N atom and a neighboring C atom of the pyridinium cation are statistically disordered with an occupancy ratio of 0.58 (2:0.42 (2.
11. Alkylation of pyridines at their 4-positions with styrenes plus yttrium reagent or benzyl Grignard reagents.
Science.gov (United States)
Mizumori, Tomoya; Hata, Takeshi; Urabe, Hirokazu
2015-01-02
A new regioselective alkylation of pyridines at their 4-position was achieved with styrenes in the presence of yttrium trichloride, BuLi, and diisobutylaluminium hydride (DIBAL-H) in THF. Alternatively, similar products were more simply prepared from pyridines and benzyl Grignard reagents. These reactions are not only a useful preparation of 4-substituted pyridines but are also complementary to other relevant reactions usually giving 2-substituted pyridines. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
12. Plasma-polymerized perfluoro(methylcyclohexane) coating on ethylene propylene diene elastomer surface: Effect of plasma processing condition on the deposition kinetics, morphology and surface energy of the film
International Nuclear Information System (INIS)
Tran, N.D.; Dutta, N.K.; Choudhury, N. Roy
2005-01-01
Plasma polymerization of perfluoro (methylcyclohexane) was carried out under cold plasma process operated at 13.56 MHz to deposit pore-free, uniform, ultra-thin film on an ethylene propylene diene terpolymer (EPDM) substrate in a view to modify the surface characteristics. The plasma fluoropolymeric films were formed at different plasma treatment times (from 20 s to 16 min), applied powers (20 to 100 W) and precursor flow rates to produce high quality films in a controllable yet tunable fashion. Scanning electron microscopy was employed successfully to characterize the evolution of the morphological feature in the film and also to determine the thickness of the coating. The surface energy of the film was determined by sessile drop method using different solvents as probe liquids. It is observed that a pore-free homogeneous plasma polymer thin film is formed within 20 s of treatment time, however, the morphology of the film depends on the plasma processing conditions, such as plasma power, precursor flow rate and deposition time. With increased time and power at a constant flow rate, the morphology of the film progressively changes from flat smooth to globular and rough. The kinetics and activation energy of the plasma polymer film deposition process were also estimated. The surface energy of the EPDM substrate decreased dramatically with plasma coating, however, it appears to be independent of the treatment time
13. 2-Aminobenzoic acid–4-[2-(pyridin-4-yl)ethyl]pyridine (2/1)
OpenAIRE
Arman, Hadi D.; Tiekink, Edward R. T.
2013-01-01
The asymmetric unit of the title co-crystal, C12H12N2·2C7H7NO2, comprises a centrosymmetric 4-[2-(pyridin-4-yl)ethyl]pyridine molecule and a 2-aminobenzoic acid molecule in a general position. The acid has a small twist between the carboxylic acid residue and the ring [dihedral angle = 7.13 (6)°] despite the presence of an intramolecular N—H...O(carbonyl) hydrogen bond. Three-molecule aggregates are formed via O—H...N(pyridyl) hydrogen bonds, and these are connecte...
14. Synthesis of 1-Substituted-4-(Pyridin-4-yl)
African Journals Online (AJOL)
Purpose: To synthesize a new series of 1-substituted-4-(pyridin-4-yl) [1,2,4] triazolo [4,3-a]quinazolin- 5(4H)-ones and evaluate them for H1-antihistaminic activity with negligible side effects in guinea pigs. Methods: The synthesized compounds were characterized by Infrared spectroscopy (IR), proton nuclear magnetic ...
15. Butane-1,4-diyl bis(pyridine-4-carboxylate
Directory of Open Access Journals (Sweden)
J. Muthukumaran
2011-07-01
Full Text Available The molecule of the title compound, C16H16N2O4, lies about an inversion centre; the butane chain adopts an extended zigzag conformation. The dihedral angle between the pyridine ring and the adjacent COO group is 3.52 (s14°.
16. Expanding the chemical diversity of spirooxindoles via alkylative pyridine dearomatization
Directory of Open Access Journals (Sweden)
Chunhui Dai
2012-07-01
Full Text Available A mild and practical synthesis of spirooxindole [1,3]oxazino derivatives from N-substituted isatins and 1,3-dicarbonyl compounds with pyridine derivatives is reported. The reactions provided good to excellent yields. Further exploration of the molecular diversity of these compounds is demonstrated through Diels–Alder reactions.
17. Pulse radiolysis of pyridine and methylpyridines in aqueous solutions
DEFF Research Database (Denmark)
Solar, S.; Getoff, N.; Sehested, K.
1993-01-01
The radicals formed from pyridine, 3-methylpyridine, 3,5-dimethylpyridine, 2,6-dimethylpyridine and 2,4,6-trimethylpyridine by attack of H, e(aq)-, OH and O.- in aqueous solutions were investigated by pulse radiolysis in the pH-range 1-13.8. The UV-vis. absorption spectra as well as the formation...
18. New pinene-derived pyridines as bidentate chiral ligands
Czech Academy of Sciences Publication Activity Database
Malkov, A. V.; Stewart-Liddon, A.; Teplý, Filip; Kobr, L.; Muir, K. W.; Haigh, D.; Kočovský, P.
2008-01-01
Roč. 64, č. 18 (2008), s. 4011-4025 ISSN 0040-4020 Institutional research plan: CEZ:AV0Z40550506 Keywords : chiral ligands * transition metal catalysis * asymmetric catalysis * pyridine ligands * oxazoline ligands Subject RIV: CC - Organic Chemistry Impact factor: 2.897, year: 2008
19. Electrochemistry of ruthenium acetate trigonal cluster with dimethylsulfoxide and pyridine
International Nuclear Information System (INIS)
Alexiou, A.D.P.; Toma, H.E.
1990-01-01
The electrochemical behaviour of asymetric cluster with two ligands, pyridine and dimethyl-sulfoxide is studied for determining the changes from cluster oxidation influence on DMSO-Ru ligand and for verifying the ligand isomers which were detected in two systems; [Ru(NHsub(3))dmso] sup(3+/2+) [9] and [Ru(edta)dmso] sup(1-/2-)[10]. (author)
20. Lithium salt of N,N-dimethylsalicylamide in pyridine and pyridine-water solutions. NMR study on the internal rotation about the C-N bond
Energy Technology Data Exchange (ETDEWEB)
Gryff-Keller, A; Szczecinski, P [Politechnika Warszawska (Poland)
1981-01-01
NMR spectra of the title compound in pyridine and pyridine-water mixtures have been measured at various temperatures. The dependence of internal rotation rate and of chemical shift difference between N-CH/sub 3/ signals on the solvent composition has been discussed with reference to structure of the solution investigated.
1. On the one pot syntheses of chromeno[4,3-b]pyridine-3-carboxylate and chromeno[3,4-c]pyridine-3-carboxylate and dihydropyridines
Energy Technology Data Exchange (ETDEWEB)
Navarrete-Encina, Patricio A.; Vega-Retter, Christian, E-mail: [email protected] [Universidad de Chile, Santiago (Chile). Facultad de Ciencias Quimicas y Farmaceuticas. Lab. de Sintesis Organica y Fisicoquimica; Salazar, Ricardo; Perez, Karina; Squella, Juan A.; Nunez-Vergara, Luis J. [Universidad de Chile, Santiago (Chile). Fac. de Ciencias Quimicas y Farmaceuticas. Lab. de Bioelectroquimica
2010-07-01
Substituted chromenos, dihydropyridines and pyridines have been important in the syntheses of compounds having interesting pharmacological properties. Therefore, we found of interest to synthesize chromenopyridines and chromeno dihydropyridines (i.e., fused chromeno and dihydropyridine or pyridine rings) to further study their biological activity. Here, we propose one-pot syntheses for substituted ethyl-2,4-dimethyl-5-oxo-5H-chromeno[4,3-b]pyridine-3-carboxylates, ethyl-2,4-dimethyl-5-oxo-5H-chromeno[3,4-c]pyridine-3-carboxylates and their respective 1,4-dihydropyridines based on a modified Hantzsch pyridine synthesis using 2-hydroxyaryl aldehydes, with electron withdrawing and electron donating groups on the phenyl ring, as starting reactants. Sixteen compounds were synthesized by the described method and fully characterized. An average yield of 37% was obtained for the different derivatives. (author)
2. On the one pot syntheses of chromeno[4,3-b]pyridine-3-carboxylate and chromeno[3,4-c]pyridine-3-carboxylate and dihydropyridines
International Nuclear Information System (INIS)
Navarrete-Encina, Patricio A.; Vega-Retter, Christian; Salazar, Ricardo; Perez, Karina; Squella, Juan A.; Nunez-Vergara, Luis J.
2010-01-01
Substituted chromenos, dihydropyridines and pyridines have been important in the syntheses of compounds having interesting pharmacological properties. Therefore, we found of interest to synthesize chromenopyridines and chromeno dihydropyridines (i.e., fused chromeno and dihydropyridine or pyridine rings) to further study their biological activity. Here, we propose one-pot syntheses for substituted ethyl-2,4-dimethyl-5-oxo-5H-chromeno[4,3-b]pyridine-3-carboxylates, ethyl-2,4-dimethyl-5-oxo-5H-chromeno[3,4-c]pyridine-3-carboxylates and their respective 1,4-dihydropyridines based on a modified Hantzsch pyridine synthesis using 2-hydroxyaryl aldehydes, with electron withdrawing and electron donating groups on the phenyl ring, as starting reactants. Sixteen compounds were synthesized by the described method and fully characterized. An average yield of 37% was obtained for the different derivatives. (author)
3. Pyridine-induced Dimensionality Change in Hybrid Perovskite Nanocrystals
KAUST Repository
2017-05-02
Engineering the surface energy through careful manipulation of the surface chemistry is a convenient approach to control quantum confinement and structure dimensionality during nanocrystal growth. Here, we demonstrate that the introduction of pyridine during the synthesis of methylammonium lead bromide (MAPbBr) perovskite nanocrystals can transform three-dimensional (3D) cubes into two-dimensional (2D) nanostructures. Density functional theory (DFT) calculations show that pyridine preferentially binds to Pb atoms terminating the surface, driving the selective 2D growth of the nanostructures. These 2D nanostructures exhibit strong quantum confinement effects, high photoluminescence quantum yields in the visible spectral range, and efficient charge transfer to molecular acceptors. These qualities indicate the suitability of the synthesized 2D nanostructures for a wide range of optoelectronic applications.
4. Pyridine Vapors Detection by an Optical Fibre Sensor
Directory of Open Access Journals (Sweden)
2008-02-01
Full Text Available An optical fibre sensor has been implemented towards pyridine vapors detection;to achieve this, a novel vapochromic material has been used, which, in solid state, suffers achange in colour from blue to pink-white in presence of pyridine vapours. This complex isadded to a solution of PVC (Poly Vinyl Chloride, TBP (Tributylphosphate andtetrahydrofuran (THF, forming a plasticized matrix; by dip coating technique, the sensingmaterial is fixed onto a cleaved ended optical fibre. The fabrication process was optimizedin terms of number of dips and dipping speed, evaluating the final devices by dynamicrange. Employing a reflection set up, the absorbance spectra and changes in the reflectedoptical power of the sensors were registered to determine their response. A linear relationbetween optical power versus vapor concentration was obtained, with a detection limit of 1ppm (v/v.
5. Theoretical investigations on fluorene-pyridines as electroactive sensor molecules
International Nuclear Information System (INIS)
Horner, S.; Romaner, L.; Zojer, E.; Kappaun, S.; Slugovc, C.; Kelterer, A.-M.
2006-01-01
Full text: Organic semiconducting oligomers and polymers are promising candidates for chemical sensing applications. In this work, sensor molecules comprising a sequence of para- and meta-linked fluorene- and pyridine- units are studied. Spectroscopic investigations show that upon protonation of the pyridine rings (i.e., when adding acids to the solutions), one observes a distinct red-shift of the absorption and emission maxima by approximately 0.5 eV. The fact that the polymers are highly emissive in both, the non protonated as well as protonated state makes them particularly interesting candidates for ratio metric sensors based on organic semiconductors. To rationalize the observed behaviour, we calculate the geometric and electronic structures of the relevant molecules at various stages of protonation using both semiempirical as well as density functional theory based methods. In general, we obtain good agreement between theory and experiment and excited state localization is found to play a crucial role in the sensing process. In practice, one can expect the interaction between the proton and the nitrogen of the pyridine unit to be modulated by interaction with the counter-ion as well as by screening through solvent molecules. These effects are accounted for in calculations on smaller model systems. (author)
6. Crystal Structure and Properties of Imidazo-Pyridine Ionic Liquids.
Science.gov (United States)
Farren-Dai, Marco; Cameron, Stanley; Johnson, Michel B; Ghandi, Khashayar
2018-07-05
Computational studies were performed on novel protic ionic liquids imidazolium-[1,2-a]-pyridine trifluoroacetate [ImPr][TFA] synthesized by the reaction of imidazo-[1,2a]-pyridine (ImPr) with trifluoroacetic acid (TFA), and on fused salt imidazolium-[1,2-a]-pyridine maleamic carbonate [ImPr][Mal] synthesized by reaction of ImPr with maleamic acid (Mal). Synthesis was performed as one-pot reactions, which applies green chemistry tenets. Both these compounds begin to decompose at 180°C. Our computational studies suggest another thermal reaction channel, in which [ImPr][Mal] can also thermally polymerizes to polyacrylamide which then cyclizes. This is thermal product remains stable up to 700 degrees, consistent with our thermogravimetric studies. [ImPr][TFA] exhibited good conductivity and ideal ionic behavior, as evaluated by a Walden plot. X-ray crystallography of [ImPr][TFA] revealed a tightly packed system for the crystals as a result of strong ionic interaction, pi-stacking, and fluorine-CH interactions. Both synthesized compounds exhibited some CO 2 absorptivity, with [ImPr][Mal] outperforming [ImPr][TFA] in this regard. The quantum chemistry based computational methods can shed light on many properties of these ionic liquids, but they are challenged in fully describing their ionic nature. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
7. 2-Aminobenzoic acid–4-(pyridin-4-yldisulfanylpyridine (1/1
Directory of Open Access Journals (Sweden)
2011-12-01
Full Text Available The title 1:1 co-crystal, C7H7NO2·C10H8N2S2, features a highly twisted 4-(pyridin-4-yldisulfanylpyridine molecule [dihedral angle between the pyridine rings = 89.06 (10°]. A small twist is evident in the 2-aminobenzoic acid molecule, with the C—C—C—O torsion angle being −7.7 (3°. An N—H...O hydrogen bond occurs in the 2-aminobenzoic acid molecule. In the crystal, molecules are linked by O—H...N and N—H...N hydrogen bonds into a supramolecular chain along the b axis. These are connected into layers by π–π interactions occurring between pyridine rings [centroid–centroid distance = 3.8489 (15 Å]. The layers are connected along the a axis by C—H...O contacts. The crystal studied was a racemic twin.
8. Molecular Dynamics and Neutron Scattering Studies of Mixed Solutions of Caffeine and Pyridine in Water.
Science.gov (United States)
Tavagnacco, Letizia; Mason, Philip E; Neilson, George W; Saboungi, Marie-Louise; Cesàro, Attilio; Brady, John W
2018-05-31
Insight into the molecular interactions of homotactic and heterotactic association of caffeine and pyridine in aqueous solution is given on the basis of both experimental and simulation studies. Caffeine is about 5 times more soluble in a 3 m aqueous pyridine solution than it is in pure water (an increase from ∼0.1 m to 0.5 m). At this elevated concentration the system becomes suitable for neutron scattering study. Caffeine-pyridine interactions were studied by neutron scattering and molecular dynamics simulations, allowing a detailed characterization of the spatial and orientational structure of the solution. It was found that while pyridine-caffeine interactions are not as strong as caffeine-caffeine interactions, the pyridine-caffeine interactions still significantly disrupted caffeine-caffeine stacking. The alteration of the caffeine-caffeine stacking, occasioned by the presence of pyridine molecules in solution and the consequent formation of heterotactic interactions, leads to the experimentally detected increase in caffeine solubility.
Directory of Open Access Journals (Sweden)
Abdelhakim Laachir
2017-03-01
Full Text Available The cation of the title molecular salt, C12H9N4S+·ClO4−, is approximately planar, with the pyridine and pyridinium rings being inclined to the central thiadiazole ring by 6.51 (9 and 9.13 (9°, respectively. The dihedral angle between the pyridine and pyridinium rings is 12.91 (10°. In the crystal, the cations are linked by N—H...O and C—H...O hydrogen bonds, involving the perchlorate anion, forming chains propagating along the [100] direction. The chains are linked by weak offset π–π interactions [inter-centroid distance = 3.586 (1 Å], forming layers parallel to the ab plane.
10. Mechanistic studies of plasma polymerization of allylamine
Czech Academy of Sciences Publication Activity Database
Chourkov, A.; Biederman, H.; Slavinská, D.; Hanley, L.; Macková, Anna; Grinevich, A.; Boldryeva, H.
2005-01-01
Roč. 109, č. 48 (2005), s. 23086-23095 ISSN 1520-6106 Institutional research plan: CEZ:AV0Z10480505 Keywords : quartz-crystal microbalance * atomic-force microscopy * guide mode spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.033, year: 2005
11. Redução da hidrofilicidade de filmes biodegradáveis à base de amido por meio de polimerização por plasma Reduction of hydrophilicity of biodegradable starch-based films by plasma polymerization
Directory of Open Access Journals (Sweden)
Rossana M. S. M. Thiré
2004-03-01
Full Text Available Devido ao baixo custo de produção e excelente biodegradabilidade, o amido constitui-se em matéria-prima promissora para a produção de plásticos biodegradáveis. No entanto, a grande hidrofilicidade dos filmes à base de amido representa uma séria limitação tecnológica à sua comercialização, uma vez que as propriedades dos filmes são afetadas pela variação da umidade relativa do ar durante a sua estocagem ou o seu uso. Neste trabalho, filmes de amido termoplástico foram recobertos com uma fina camada protetora polimérica gerada por intermédio da tecnologia de plasma frio. 1-Buteno e 1,3-butadieno foram utilizados como monômeros para a polimerização por plasma. Os filmes recobertos apresentaram uma redução de até 80% na absorção de água e aumento do ângulo de contato em relação à água. Estes resultados indicaram uma redução significativa na natureza hidrofílica do material à base de amido após o recobrimento.Due to low cost and excellent biodegradability, the use of starch as a raw material for bioplastic production is growing in interest. However, the properties of starch-based materials are affected by relative humidity during their use and storage due to their hydrophilic character. In this work, thermoplastic cornstarch films were coated by cold plasma technology with a protective thin layer in order to reduce water sensitivity. 1-Butene and 1,3-butadiene were used as monomers for plasma polymerization. Coated films presented a reduction of water absorption up to 80% an increase in contact angle related to water. These results indicated that the coating process reduced significantly the hydrophilic nature of the starch-based materials.
12. Structure of fullerene aggregates in pyridine/water solutions by small-angle neutron scattering
International Nuclear Information System (INIS)
Aksenov, V.L.; Belushkin, A.V.; Avdeev, M.V.; Rosta, L.; Mihailovic, D.; Mrzel, A.; Serdyuk, I.N.; Timchenko, A.A.
2001-01-01
Results of small-angle neutron scattering experiments on fullerenes (C 60 ) in pyridine/water solutions are reported. They confirm conclusions of the previous studies, in particular, dynamic light scattering experiments. Aggregates with characteristic radius of about 20 nm are formed in the solutions. The contrast variation using different combinations of protonated/deuterated components (water and pyridine) of the solutions points to the small pyridine content inside the aggregates. This fact testifies that the aggregates consist of a massive fullerene core covered by a thin pyridine shell
13. Kinetic study of the substitution of pyridine by cyanide in the bis(pyridine)cobalt(III)hematoporphyrin-IX: distinguishing between Isub(d) and D mechanism
International Nuclear Information System (INIS)
Birush, M.; Pribanicj, M.
1977-01-01
''Mass-law (rate) retardation'' effect shows that the reaction between the cyanide ion and bis(pyridine)cobalt(III)hematoporphyrin-IX complex to give (CN) 2 cobalt(III)hematoporphyrin-IX occurs by a purely dissociative (D but not Isub(d)) mechanism in chloroform. Limiting rate constant at the excess of cyanide ion concentration at 25 deg C was found to be 2.5x10 -3 S -1 and the competition ratio of pyridine (ksub(-) 1 ) and the cyanide ion (k 2 ) for a five coordinate intermediate (pyridin) cobalt(III)hematoporphyrin-IX complex was obtained as ksub(-) 1 /k 2 =0.35. (author)
14. (Pyridine-2-aldoximato-κ2N,N′bis[2-(pyridin-2-ylphenyl-κ2C1,N]iridium(III
Directory of Open Access Journals (Sweden)
Bimal Chandra Singh
2013-03-01
Full Text Available In the title complex, [Ir(C11H8N2(C6H5N2O], the octahedrally coordinated IrIII atom is bonded to two 2-(pyridin-2-ylphenyl ligands, through two phenyl C and two pydidine N atoms, and to one pyridine-2-aldoxime ligand through a pyridine N and an oxime N atom. The oxime O atom of the aldoxime unit forms intermolecular C—H...O hydrogen bonds, which result in a two-dimensional hydrogen-bonded polymeric network parallel to (100. C—H...π interactions are also observed.
15. Poly[diaqua(μ5-pyridine-3,5-dicarboxylatostrontium
Directory of Open Access Journals (Sweden)
Dan Li
2012-06-01
Full Text Available In the structure of the title compound, [Sr(C7H3NO4(H2O2]n, the SrII cation is eight-coordinated in form of a distorted dodecahedron by two water O atoms and by five O atoms and one N atom from five pyridine-3,5-dicarboxylate anions. The bridging mode of the anions leads to the formation of a layered network parallel to (100. O—H...O hydrogen bonding between the coordinating water molecules and the carboxylate groups of adjacent layers consolidates the crystal packing. Weak C—H...O interactions are also observed.
16. Aquabis(methacrylato-κObis(pyridine-κNcopper(II
Directory of Open Access Journals (Sweden)
Bin Wu
2009-05-01
Full Text Available In the crystal structure of the title complex, [Cu(C4H5O22(C5H5N2(H2O], the CuII cation is located on a twofold rotation axis and coordinated by two methylacrylate anions, two pyridine ligands and one water molecule in a distorted square-pyramidal geometry. The coordinated water molecule is also located on the twofold axis. In the crystal structure O—H...O hydrogen bonds link the molecules, forming chains along the c axis.
17. (E-2-(4-Chlorophenoxy-N′-(pyridin-4-ylmethylideneacetohydrazide
Directory of Open Access Journals (Sweden)
Xiao-jin Rao
2013-01-01
Full Text Available In the title compound, C14H12ClN3O2, the acylhydrazone base [C(=O—N—N=C] is essentially planar, with an r.m.s. deviation of 0.0095 Å, and makes a dihedral angle of 12.52 (10°with the pyridine ring. In the crystal, molecules are linked via pairs of N—H...O hydrogen bonds, forming inversion dimers with an R22(8 graph-set motif. The dimers are linked via C—H...π interactions forming chains along [101].
18. Bis(pyridine-2-carbaldehyde thiosemicarbazonezinc(II dinitrate dihydrate
Directory of Open Access Journals (Sweden)
Jian-Quan Wang
2010-10-01
Full Text Available The asymmetric unit of the title compound, [Zn(C7H8N4S2](NO32·2H2O, contains two Zn(pht2 cations (pht is pyridine-2-carbaldehyde thiosemicarbazone, four nitrate anions and four water molecules. In the cations, each ZnII ion adopts a distorted octahedral coordination geometry, being chelated by two tridentate pht ligands. In the crystal, the cations, anions and water molecules are connected via O—H...O and N—H...O hydrogen bonds into a three-dimensional network.
19. Removal of pyridine from liquid and gas phase by copper forms of natural and synthetic zeolites
International Nuclear Information System (INIS)
Rehakova, Maria; Fortunova, Lubica; Bastl, Zdenek; Nagyova, Stanislava; Dolinska, Silvia; Jorik, Vladimir; Jona, Eugen
2011-01-01
Zeoadsorbents on the basis of copper forms of synthetic zeolite ZSM5 and natural zeolite of the clinoptilolite type (CT) have been studied taking into account their environmental application in removing harmful pyridine (py) from liquid and gas phase. Sorption of pyridine by copper forms of zeolites (Cu-ZSM5 and Cu-CT) has been studied by CHN, X-ray photoelectron spectroscopy, X-ray powder diffractometry, FTIR spectroscopy, thermal analysis (TG, DTA and DTG) and analysis of the surface areas and the pore volumes by low-temperature adsorption of nitrogen. The results of thermal analyses of Cu-ZSM5, Cu-(py) x ZSM5, Cu-CT and Cu-(py) x CT zeolitic products with different composition (x depends on the experimental conditions of sorption of pyridine) clearly confirmed their different thermal properties as well as the sorption of pyridine. In the zeolitic pyridine containing samples the main part of the pyridine release process occurs at considerably higher temperatures than is the boiling point of pyridine, which proves strong bond and irreversibility of py-zeolite interaction. FTIR spectra of Cu-(py) x zeolite samples showed well resolved bands of pyridine. The results of thermal analysis and FTIR spectroscopy are in a good agreement with the results of other used methods.
20. A new multicomponent reaction for the synthesis of pyridines via cycloaddition of azadienes and ketenimines
NARCIS (Netherlands)
Coffinier, D.; El Kaim, L.; Grimaud, L.; Ruijter, E.; Orru, R.V.A.
2011-01-01
The ketenimines resulting from a Nef isocyanide/Perkow sequence react with 1-azadienes to form pyridines or pyrimidines depending on their substitution pattern. The reaction is most efficient with ester-substituted ketenimines which leads to pyridines after elimination of the phosphate group. © 2011
1. Synthesis of a novel class of some biquinoline pyridine hybrids via
A small library of novel class of biquinoline containing pyridine moiety were synthesized by a one-pot cyclocondensation of 2-chloro-3-formyl quinoline, active methylene compounds and 3-(pyridine-3- ylamino)cyclohex-2-enone in the presence of catalytic amount of sodium hydroxide. The protocol offers rapid synthesis of ...
2. Degradation of pyridine and quinoline in aqueous solution by gamma radiation
Science.gov (United States)
Chu, Libing; Yu, Shaoqing; Wang, Jianlong
2018-03-01
In present work, the degradation of two N-heteroaromatic pollutants, i.e., pyridine and quinoline was investigated by gamma irradiation in the presence of TiO2 nanoparticle. The experimental results showed that quinoline has a higher degradation rate than pyridine. The removal efficiency of the pollutants, TOC and TN reached 93.0%, 11.9% and 12.0% for quinoline, 71.0%, 10.6% and 4.4% for pyridine, respectively at 7.0 kGy and initial concentration of 50 mg/L. Ammonium was detected for both pyridine and quinoline within the absorbed doses, suggesting that the organic nitrogen was transformed into ammonium. The degradation rate constant of pyridine and quinoline was increased by 1.1-1.5 times with addition of TiO2. TiO2 nanoparticles were especially effective to enhance the mineralization. The removal efficiency of TOC and TN was increased by 15-12% for pyridine and 23-25% for quinoline, respectively in the presence of 2.0 g/L TiO2. Following gamma irradiation, 2-hydroxypyridine, 3-hydroxypyridine, oxalic acid and formic acid were identified for pyridine and the hydroxyl quinoline and formic acid were detected for quinoline. Accordingly, the degradation mechanism of pyridine and quinoline by gamma irradiation was tentatively proposed.
3. Triazole-pyridine ligands: a novel approach to chromophoric iridium arrays
NARCIS (Netherlands)
Juríček, M.; Felici, M.; Contreras-Carballada, P.; Lauko, J.; Bou, S.R.; Kouwer, P.H.J.; Brouwer, A.M.; Rowan, A.E.
2011-01-01
We describe a novel modular approach to a series of luminescent iridium complexes bearing triazole-pyridine-derived ligands that were conveniently prepared by using "click" chemistry. One, two or three triazole-pyridine units were effectively built into the heteroaromatic macromolecule using
4. NHC Versus Pyridine: How “Teeth” Change the Redox Behavior of Iron(II) Complexes
KAUST Repository
Weiss, Daniel T.; Anneser, Markus R.; Haslinger, Stefan; Pö thig, Alexander; Cokoja, Mirza; Basset, Jean-Marie; Kü hn, Fritz E.
2015-01-01
A series of octahedral iron(II) complexes with tetradentate NHC/pyridine hybrid ligands containing up to three pyridyl units was designed to study the influence of NHC and pyridine donors on the electronic structure of the metal center. Structural
5. 3-Ethyl-5-(4-methoxyphenoxy-2-(pyridin-4-yl-3H-imidazo[4,5-b]pyridine
Directory of Open Access Journals (Sweden)
S. Ranjith
2011-07-01
Full Text Available In the title compound, C20H18N4O2, the imidazopyridine fused ring system is almost perpendicular to the benzene ring [dihedral angle = 87.6 (5°]. The pyridine ring makes a dihedral angle of 35.5 (5° with the mean plane of the imidazopyridine fragment. The crystal structure is stabilized by an aromatic π–π stacking interaction between the phenyl rings of neighbouring molecules [centroid–centroid distance = 3.772 (2 Å, interplanar distance = 3.546 (2 Å and slippage = 1.286 (2 Å].
6. Hexaaquanickel(II tetraaquabis(μ-pyridine-2,6-dicarboxylatobis(pyridine-2,6-dicarboxylatotrinickelate(II octahydrate
Directory of Open Access Journals (Sweden)
2010-08-01
Full Text Available The title compound, [Ni(H2O6][Ni3(C7H3NO44(H2O4]·8H2O, was obtained by the reaction of nickel(II nitrate hexahydrate with pyridine-2,6-dicarboxylic acid (pydcH2 and 1,10-phenanothroline (phen in an aqueous solution. The latter ligand is not involved in formation of the title complex. There are three different NiII atoms in the asymmetric unit, two of which are located on inversion centers, and thus the [Ni(H2O6]2+ cation and the trinuclear {[Ni(pydc2]2-μ-Ni(H2O4}2− anion are centrosymmetric. All NiII atoms exhibit an octahedral coordination geometry. Various interactions, including numerous O—H...O and C—H...O hydrogen bonds and C—O...π stacking of the pyridine and carboxylate groups [3.570 (1, 3.758 (1 and 3.609 (1 Å], are observed in the crystal structure.
7. Crystal structure of 2-hydroxyimino-2-(pyridin-2-yl-N′-[1-(pyridin-2-ylethylidene]acetohydrazide
Directory of Open Access Journals (Sweden)
Maxym O. Plutenko
2014-12-01
Full Text Available The molecule of the title compound, C14H13N5O2, is approximately planar (r.m.s deviation for all non-H atoms = 0.093 Å, with the planes of the two pyridine rings inclined to one another by 5.51 (7°. The oxime group is syn to the amide group, probably due to the formation of an intramolecular N—H...N hydrogen bond that forms an S(6 ring motif. In the crystal, molecules are linked by pairs of bifurcated O—H...(O,N hydrogen bonds, forming inversion dimers. The latter are linked via C—H...O and C—H...N hydrogen bonds, forming sheets lying parallel to (502. The sheets are linked via π–π stacking interactions [inter-centroid distance = 3.7588 (9 Å], involving the pyridine rings of inversion-related molecules, forming a three-dimensional structure.
8. Determination of pyridine in soil and water samples of a polluted area
International Nuclear Information System (INIS)
Peters, R.J.B.; Renesse van Duivenbode, J.A.D. van
1994-01-01
A method for the analyses of pyridine in environmental samples is described. For soil samples a distillation procedure followed by an extraction, an acidic extraction or a Soxhlet extraction can be used. For water samples a distillation procedure followed by extraction can be employed. Deuterated pyridine is used as an internal standard and the extracts are analyzed by GC-MS. The recoveries of the methods are higher than 80%; the detection limits for pyridine are 0.01 mg/kg for soil samples and 0.2 μg/l for water samples. (orig.)
9. Surface enhanced raman scattering at Ag-Pyridine interface by use of long range surface plasmon
International Nuclear Information System (INIS)
Baik, Moon Gu; Ko, Eu; Kwan, Do Kyeong; Lee, Ja Hyung; Chang, Joon Sung
1990-01-01
Surface-enhanced Raman scattering (SERS) experiment of pyridine (C 5 H 5 N) has been performed at silverpyridine interface by use of long range surface plasmon (LRSP) which is generated in the Sarid-type attenuated total reflection (ATR) structure consisting of prism, dielectic, metal and dielectic media. Generation of LRSP has been confirmed by observing the propagation of the LRSP. Raman signal of pyridine adsorbed on the silver surface in the above layered structure has been observed and compared with the bulk Raman signal and SERS signal from the chemically adsorbed pyridine. SERS experiment by use of LRSP has not yet reported to the best of our knowledge. (Author)
10. SERS spectra of pyridine adsorbed on nickel film prepared by magnetron sputtering
Science.gov (United States)
Li, Daoyong; Ouyang, Yu; Chen, Li; Cao, Weiran; Shi, Shaohua
2011-02-01
As a repeating well and cheaper enhancement substrate, the nickel film was fabricated with magnetron sputtering coating instrument. Surface enhanced Raman spectra (SERS) of pyridine adsorbed on this nickel film are compared with the experimental values of gaseous pyridine, the theoretical value of pyridine solution listed in other literatures and our method is better than electro-chemical etching electrode method for large scale preparation. The enhancement factor of the nickel film is calculated and the result indicates that magnetron sputtering coating technology is feasible for obtaining good SERS active surface.
11. Synthesis and characterization of oxovanadium (IV) dithiocarbamates with pyridine
Energy Technology Data Exchange (ETDEWEB)
2002-07-01
We report the synthesis and study of a new series of oxovanadium (IV) dithiocarbamate adducts and derivatives with pyridine and cyclohexyl, di-iso-butyl, di-n-propyl, aniline, morpholine, piperidine and di-iso-propyl amines. The complexes have been characterized by analytical, magneto chemical, IR, visible-UV spectral and thermal studies, and are assigned the formulas [VO(L){sub 2}].py, where L=cyclohexyl, di-iso-butyl, di-n-propyl, aniline dithiocarbamate and [VO(OH)(L)(py){sub 2}] OH.H{sub 2}O (L=morpholine, piperidine and di-iso-propyl dithiocarbamate). The effect of the adduct formation on the p{sub V=0} bound is discussed in terms of the IR (V=O, V-S and V-N stretching frequencies) and electronic spectra (d-d transitions). (author)
12. Unconventional hydrogen bonding to organic ions in the gas phase: Stepwise association of hydrogen cyanide with the pyridine and pyrimidine radical cations and protonated pyridine
Energy Technology Data Exchange (ETDEWEB)
Hamid, Ahmed M.; El-Shall, M. Samy, E-mail: [email protected] [Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Hilal, Rifaat; Elroby, Shaaban; Aziz, Saadullah G. [Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)
2014-08-07
Equilibrium thermochemical measurements using the ion mobility drift cell technique have been utilized to investigate the binding energies and entropy changes for the stepwise association of HCN molecules with the pyridine and pyrimidine radical cations forming the C{sub 5}H{sub 5}N{sup +·}(HCN){sub n} and C{sub 4}H{sub 4}N{sub 2}{sup +·}(HCN){sub n} clusters, respectively, with n = 1–4. For comparison, the binding of 1–4 HCN molecules to the protonated pyridine C{sub 5}H{sub 5}NH{sup +}(HCN){sub n} has also been investigated. The binding energies of HCN to the pyridine and pyrimidine radical cations are nearly equal (11.4 and 12.0 kcal/mol, respectively) but weaker than the HCN binding to the protonated pyridine (14.0 kcal/mol). The pyridine and pyrimidine radical cations form unconventional carbon-based ionic hydrogen bonds with HCN (CH{sup δ+}⋯NCH). Protonated pyridine forms a stronger ionic hydrogen bond with HCN (NH{sup +}⋯NCH) which can be extended to a linear chain with the clustering of additional HCN molecules (NH{sup +}⋯NCH··NCH⋯NCH) leading to a rapid decrease in the bond strength as the length of the chain increases. The lowest energy structures of the pyridine and pyrimidine radical cation clusters containing 3-4 HCN molecules show a strong tendency for the internal solvation of the radical cation by the HCN molecules where bifurcated structures involving multiple hydrogen bonding sites with the ring hydrogen atoms are formed. The unconventional H-bonds (CH{sup δ+}⋯NCH) formed between the pyridine or the pyrimidine radical cations and HCN molecules (11–12 kcal/mol) are stronger than the similar (CH{sup δ+}⋯NCH) bonds formed between the benzene radical cation and HCN molecules (9 kcal/mol) indicating that the CH{sup δ+} centers in the pyridine and pyrimidine radical cations have more effective charges than in the benzene radical cation.
13. (Pyridin-2-ylmethyl 6-bromo-2-oxo-1-[(pyridin-2-ylmethyl]-1,2-dihydroquinoline-4-carboxylate
Directory of Open Access Journals (Sweden)
Yassir Filali Baba
2018-02-01
Full Text Available In the central dihydroquinoline unit of the title compound, C22H16BrN3O3, the dihydropyridinone and benzene rings are inclined to one another by 2.0 (1°, while the outer pyridine rings are almost perpendicular to the plane of the dihydroquinoline ring system. The conformation of the molecule is partially determined by an intramolecular C—H...O hydrogen bond. In the crystal, molecules stack along the b-axis direction through a combination of C—H...N and C—H...O hydrogen bonds and π–π stacking interactions involving the dihydroquinoline units, with a centroid-to-centroid distance of 3.7648 (15 Å.
14. Anti-Markovnikov hydroimination of terminal alkynes in gold-catalyzed pyridine construction from ammonia.
Science.gov (United States)
Wang, Liliang; Kong, Lingbing; Li, Yongxin; Ganguly, Rakesh; Kinjo, Rei
2015-08-11
Gold-catalyzed hydroimination of terminal alkynes, giving rise to anti-Markovnikov adducts concomitant with unstable Markovnikov adducts is described. The elementary step can be applied for the construction of pyridine derivatives from ammonia and alkynes.
15. Ugi-Smiles couplings of 4-substituted pyridine derivatives : a fast access to chloroquine analogues
NARCIS (Netherlands)
El Kaïm, Laurent; Grimaud, Laurence; Pravin, Patil; Patil, Pravin
2012-01-01
4-Hydroxy and mercapto pyridines were successfully tested in Ugi-Smiles couplings. Such multicomponent reactions applied to quinoline derivatives afford a very convenient and short synthesis of antimalarial analogues.
16. Ugi-Smiles couplings of 4-substituted pyridine derivatives: a fast access to chloroquine analogues.
Science.gov (United States)
El Kaïm, Laurent; Grimaud, Laurence; Pravin, Patil
2012-01-20
4-Hydroxy and mercapto pyridines were successfully tested in Ugi-Smiles couplings. Such multicomponent reactions applied to quinoline derivatives afford a very convenient and short synthesis of antimalarial analogues. © 2011 American Chemical Society
17. Poly[di-μ2-aqua-μ5-(pyridine-2,6-dicarboxylato-μ3-(pyridine-2,6-dicarboxylato-cobalt(IIdisodium
Directory of Open Access Journals (Sweden)
Alexander N. Boyko
2011-12-01
Full Text Available In the title compound, [CoNa2(C7H3NO42(H2O2]n, the CoII atom is coordinated by two pyridine N atoms and four carboxylate O atoms from two doubly deprotonated pyridine-2,6-dicarboxylate ligands in a distorted octahedral geometry. One Na+ cation is coordinated by three carboxylate O atoms and two water molecules and the other is coordinated by five carboxylate O atoms and two water molecules in an irregular geometry. The bis(pyridine-2,6-dicarboxylatocobalt complex units are connected by Na+ cations and bridging water molecules into a three-dimensional coordination network. O—H...O hydrogen bonds are formed between the water molecules and the carboxylate O atoms.
18. Binary and ternary cocrystals of sulfa drug acetazolamide with pyridine carboxamides and cyclic amides
OpenAIRE
Bolla, Geetha; Nangia, Ashwini
2016-01-01
A novel design strategy for cocrystals of a sulfonamide drug with pyridine carboxamides and cyclic amides is developed based on synthon identification as well as size and shape match of coformers. Binary adducts of acetazolamide (ACZ) with lactams (valerolactam and caprolactam, VLM, CPR), cyclic amides (2-pyridone, labeled as 2HP and its derivatives MeHP, OMeHP) and pyridine amides (nicotinamide and picolinamide, NAM, PAM) were obtained by manual grinding, and their single crystals by solutio...
19. N,N′-(Ethane-1,2-diyldi-o-phenylenebis(pyridine-2-carboxamide
Directory of Open Access Journals (Sweden)
Shuranjan Sarkar
2011-11-01
Full Text Available The title molecule, C26H22N4O2, is centrosymmetric and adopts an anti conformation. Two intramolecular hydrogen bonds, viz. amide–pyridine N—H...N and phenyl–amide C—H...O, stabilize the trans conformation of the (pyridine-2-carboxamidophenyl group about the amide plane. In the crystal, the presence of weak intermolecular C—H...O hydrogen bonds results in the formation of a three-dimensional network.
20. Dihydro-β-agarofuran sesquiterpene pyridine alkaloids from the seeds of Euonymus hamiltonianus
Directory of Open Access Journals (Sweden)
Mudasir A. Tantry
2016-09-01
Full Text Available Plants of the Celastraceae family produce various dihydro-β-agarofuran sesquiterpene pyridine alkaloids. Two dihydro-β-agarofuran sesquitepene pyridine alkaloids (1,2 apart from four known compounds euojaponin C (3, wilforine (4, austronine (5 and O9-benzoyl-O9-deacetylevonine (6, were isolated from the ripe seeds of Euonymus hamiltonianus. Their chemical structures were elucidated mainly by analysis of NMR and MS spectral data. All compounds were evaluated for insecticidal activity.
1. On the formation of niacin (vitamin B3) and pyridine carboxylic acids in interstellar model ices
Energy Technology Data Exchange (ETDEWEB)
McMurtry, Brandon M.; Turner, Andrew M.; Saito, Sean E.J.; Kaiser, Ralf I. [W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI 96822 (United States); Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI 96822 (United States)
2016-06-15
The formation of pyridine carboxylic acids in interstellar ice grains was simulated by electron exposures of binary pyridine (C{sub 5}H{sub 5}N)-carbon dioxide (CO{sub 2}) ice mixtures at 10 K under contamination-free ultrahigh vacuum conditions. Chemical processing of the pristine ice and subsequent warm-up phase was monitored on line and in situ via Fourier transform infrared spectroscopy to probe for the formation of new radiation induced species. In the infrared spectra of the irradiated ice, bands assigned to nicotinic acid (niacin; vitamin B3; m-C{sub 5}H{sub 4}NCOOH) along with 2,3-, 2,5-, 3,4-, and 3,5-pyridine dicarboxylic acid (C{sub 5}H{sub 3}N(COOH){sub 2}) were unambiguously identified along with the hydroxycarbonyl (HOCO) radical. Our study suggests that the reactive pathway responsible for pyridine carboxylic acids formation involves a HOCO intermediate, which forms through the reaction of suprathermal hydrogen ejected from pyridine with carbon dioxide. The newly formed pyridinyl radical may then undergo radical–radical recombination with a hydroxycarbonyl radical to form a pyridine carboxylic acid.
2. Pyridine adsorption and diffusion on Pt(111) investigated with density functional theory
International Nuclear Information System (INIS)
Kolsbjerg, Esben L.; Groves, Michael N.; Hammer, Bjørk
2016-01-01
The adsorption, diffusion, and dissociation of pyridine, C 5 H 5 N, on Pt(111) are investigated with van der Waals-corrected density functional theory. An elaborate search for local minima in the adsorption potential energy landscape reveals that the intact pyridine adsorbs with the aromatic ring parallel to the surface. Piecewise interconnections of the local minima in the energy landscape reveal that the most favourable diffusion path for pyridine has a barrier of 0.53 eV. In the preferred path, the pyridine remains parallel to the surface while performing small single rotational steps with a carbon-carbon double bond hinged above a single Pt atom. The origin of the diffusion pathway is discussed in terms of the C 2 –Pt π-bond being stronger than the corresponding CN–Pt π-bond. The energy barrier and reaction enthalpy for dehydrogenation of adsorbed pyridine into an adsorbed, upright bound α-pyridyl species are calculated to 0.71 eV and 0.18 eV, respectively (both zero-point energy corrected). The calculations are used to rationalize previous experimental observations from the literature for pyridine on Pt(111).
3. Regulation of Ca2+ release from mitochondria by the oxidation-reduction state of pyridine nucleotides
Science.gov (United States)
Lehninger, Albert L.; Vercesi, Anibal; Bababunmi, Enitan A.
1978-01-01
Mitochondria from normal rat liver and heart, and also Ehrlich tumor cells, respiring on succinate as energy source in the presence of rotenone (to prevent net electron flow to oxygen from the endogenous pyridine nucleotides), rapidly take up Ca2+ and retain it so long as the pyridine nucleotides are kept in the reduced state. When acetoacetate is added to bring the pyridine nucleotides into a more oxidized state, Ca2+ is released to the medium. A subsequent addition of a reductant of the pyridine nucleotides such as β-hydroxybutyrate, glutamate, or isocitrate causes reuptake of the released Ca2+. Successive cycles of Ca2+ release and uptake can be induced by shifting the redox state of the pyridine nucleotides to more oxidized and more reduced states, respectively. Similar observations were made when succinate oxidation was replaced as energy source by ascorbate oxidation or by the hydrolysis of ATP. These and other observations form the basis of a hypothesis for feedback regulation of Ca2+-dependent substrate- or energy-mobilizing enzymatic reactions by the uptake or release of mitochondrial Ca2+, mediated by the cytosolic phosphate potential and the ATP-dependent reduction of mitochondrial pyridine nucleotides by reversal of electron transport. Images PMID:25436
4. Investigating the Effect of Pyridine Vapor Treatment on Perovskite Solar Cells - Oral Presentation
Energy Technology Data Exchange (ETDEWEB)
Ong, Alison J. [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-08-25
Perovskite photovoltaics have recently come to prominence as a viable alternative to crystalline silicon based solar cells. In an effort to create consistent and high-quality films, we studied the effect of various annealing conditions as well as the effect of pyridine vapor treatment on mixed halide methylammonium lead perovskite films. Of six conditions tested, we found that annealing at 100 degree Celsius for 90 minutes followed by 120 degree Celsius for 15 minutes resulted in the purest perovskite. Perovskite films made using that condition were treated with pyridine for various amounts of time, and the effects on perovskite microstructure were studied using x-ray diffraction, UV-Vis spectroscopy, and time-resolved photoluminescence lifetime analysis (TRPL). A previous study found that pyridine vapor caused perovskite films to have higher photoluminescence intensity and become more homogenous. In this study we found that the effects of pyridine are more complex: while films appeared to become more homogenous, a decrease in bulkphotoluminescence lifetime was observed. In addition, the perovskite bandgap appeared to decrease with increased pyridine treatment time. Finally, X-ray diffraction showed that pyridine vapor treatment increased the perovskite (110) peak intensity but also often gave rise to new unidentified peaks, suggesting the formation of a foreign species. It was observed that the intensity of this unknown species had an inverse correlation with the increase in perovskite peak intensity, and also seemed to be correlated with the decrease in TRPL lifetime.
5. Investigating the Effect of Pyridine Vapor Treatment on Perovskite Solar Cells
Energy Technology Data Exchange (ETDEWEB)
Ong, Alison [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-08-20
Perovskite photovoltaics have recently come to prominence as a viable alternative to crystalline silicon based solar cells. In an effort to create consistent and high-quality films, we studied the effect of various annealing conditions as well as the effect of pyridine vapor treatment on mixed halide methylammonium lead perovskite films. Of six conditions tested, we found that annealing at 100°C for 90 minutes followed by 120°C for 15 minutes resulted in the purest perovskite. Perovskite films made using that condition were treated with pyridine for various amounts of time, and the effects on perovskite microstructure were studied using x-ray diffraction, UV-Vis spectroscopy, and time-resolved photoluminescence lifetime analysis (TRPL). A previous study found that pyridine vapor caused perovskite films to have higher photoluminescence intensity and become more homogenous. In this study we found that the effects of pyridine are more complex: while films appeared to become more homogenous, a decrease in bulk photoluminescence lifetime was observed. In addition, the perovskite bandgap appeared to decrease with increased pyridine treatment time. Finally, X-ray diffraction showed that pyridine vapor treatment increased the perovskite (110) peak intensity but also often gave rise to new unidentified peaks, suggesting the formation of a foreign species. It was observed that the intensity of this unknown species had an inverse correlation with the increase in perovskite peak intensity, and also seemed to be correlated with the decrease in TRPL lifetime.
6. Study by electron paramagnetic resonance of the radiolysis of pyridine N-oxide in a vitreous methanol matrix
International Nuclear Information System (INIS)
Quaegebeur, J.P.; Perly, B.
1977-01-01
The analysis of esr spectra derived from γ irradiated pyridine N-oxide in a methanolic vitreous matrix at 77 K shows the presence of a mixture of 2- and 4-azacyclohexadienyl N-oxide radicals formed by the addition of the hydroxymethyl primary species to the pyridine ring. The structure of the different radicals was determined by comparison with spectra derived from several substituted pyridine N-oxides
7. Preparation of novel pyrrolo [2,3-b]pyridine derivatives via a new concise synthetic approach
Energy Technology Data Exchange (ETDEWEB)
Guo, Na; Jia, Haiyong; You, Xing; Jiang, Du; Lu, Kui; Yu, Peng [Key Laboratory of Industrial Microbiology, Ministry of Education, College of Biotechnology, Tianjin Key Laboratory of Industry Microbiology, College of Biotechnology, Sino-French Joint Lab of Food Nutrition/Safety and Medicinal Chemistry, Tianjin University of Science and Technology, Tianjin (China)
2015-04-15
The pyrrolo[2,3-b]pyridine core structure, a bioisostere of quinolones, is found in several molecules that possess important biological activity. We describe here a new, concise, three-step synthesis of pyrrolo[2,3-b]pyridines starting from L-alanine. A series of 4,7-dihydro-4-oxo-1H-pyrrolo[2,3-b]pyridine-5-carboxylic acid derivatives, which have not been previously reported, were synthesized using this approach.
8. New pyridine derivatives as inhibitors of acetylcholinesterase and amyloid aggregation.
Science.gov (United States)
Pandolfi, Fabiana; De Vita, Daniela; Bortolami, Martina; Coluccia, Antonio; Di Santo, Roberto; Costi, Roberta; Andrisano, Vincenza; Alabiso, Francesco; Bergamini, Christian; Fato, Romana; Bartolini, Manuela; Scipione, Luigi
2017-12-01
A new series of pyridine derivatives with carbamic or amidic function has been designed and synthesized to act as cholinesterase inhibitors. The synthesized compounds were tested toward EeAChE and hAChE and toward eqBChE and hBChE. The carbamate 8 was the most potent hAChE inhibitor (IC 50 = 0.153 ± 0.016 μM) while the carbamate 11 was the most potent inhibitor of hBChE (IC 50 = 0.828 ± 0.067 μM). A molecular docking study indicated that the carbamate 8 was able to bind AChE by interacting with both CAS and PAS, in agreement with the mixed inhibition mechanism. Furthermore, the carbamates 8, 9 and 11 were able to inhibit Aβ 42 self-aggregation and possessed quite low toxicity against human astrocytoma T67 and HeLa cell lines, being the carbamate 8 the less toxic compound on both cell lines. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
9. 49 CFR 179.102-4 - Vinyl fluoride, stabilized.
Science.gov (United States)
2010-10-01
... TANK CARS Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.102... capacity stencil, MINIMUM OPERATING TEMPERATURE _ °F. (i) The tank car and insulation must be designed to..., at an ambient temperature of 90 °F. [Amdt. 179-32, 48 FR 27707, June 16, 1983, as amended at 49 FR...
10. Resonance Raman detection of iron-ligand vibrations in cyano(pyridine)(octaethylporphinato)iron(III): Effects of pyridine basicity on the Fe-CN bond strength
International Nuclear Information System (INIS)
Uno, Tadayuki; Hatano, Keiichiro; Nishimura, Yoshifumi; Arata, Yoji
1988-01-01
The influence of axial ligand basicity on the bonding of iron(III) in cyano adducts of octaethylporphyrin has been studied by resonance Raman spectroscopy. In a six-coordinate ferric low-spin complex, cyano(pyridine)(octaethylporphinato)iron(III), Fe(OEP)(CN)(py), Raman lines at 449 and 191 cm -1 were assigned to the ν(Fe-CN) and ν(Fe-py) stretching modes, respectively. When pyridine was displaced with its derivatives, py-X, where X = 4-cyano, 3-acetyl, 3-methyl, 4-methyl, 3,4-dimethyl, and 4-dimethylamino, the ν(Fe-CN) stretching frequency was found to decrease in the complex with a high pyridine basicity. It was concluded that the stronger the trans pyridine basicity, the weaker the iron-carbon (cyanide) bond. A clear frequency shift was observed in the ν 4 model, though most of the porphyrin vibrations were insensitive to the ligand substitution. The frequency of the ν 4 mode, which is the C a -N(pyrrole) breathing vibration of the porphyrin skeleton, was found to increase with an increase in pyridine basicity. This is contrary to what was found in ferrous low-spin hemes as CO complexes. The ν 4 shift in the CN complexes was explained in terms of forward π donation; donation of electrons from the porphyrin π orbital to the d π vacancy of the low-spin iron(III) weakened the C a -N(pyrrole) bonds and hence decreased the ν 4 frequency. 32 references, 8 figures
11. Pre-treatment of pyridine wastewater by new cathodic-anodic-electrolysis packing.
Science.gov (United States)
Jin, Yang; Yue, Qinyan; Yang, Kunlun; Wu, Suqing; Li, Shengjie; Gao, Baoyu; Gao, Yuan
2018-01-01
A novel cathodic-anodic-electrolysis packing (CAEP) used in the treatment of pyridine wastewater was researched, which mainly consisted of 4,4'-diamino-2,2'-disulfonic acid (DSD acid) industrial iron sludge. The physical properties and morphology of the packing were studied. The CAEP was used in a column reactor during the pretreatment of pyridine wastewater. The influence of pH, hydraulic retention time (HRT), the air-liquid ratio (A/L) and the initial concentration of pyridine were investigated by measuring the removal of total organic carbon (TOC) and pyridine. The characterization results showed that the bulk density, grain density, water absorption percentage and specific surface area were 921kg/m 3 , 1086kg/m 3 , 25% and 29.89m 2 /g, respectively; the removal of TOC and pyridine could reach 50% and 58% at the optimal experimental conditions (pH=3, HRT=8hr, A/L=2). Notably, the surface of the packing was renewed constantly during the running of the filter, and the handling capacity was stable after running for three months. Copyright © 2017. Published by Elsevier B.V.
12. (He 1) photoelectron spectra of vinyl- and (1-dimethylaminovinyl)pyridines
International Nuclear Information System (INIS)
Baidin, V.N.; Koikov, L.N.; Terent'ev, P.B.; Gloriozov, I.P.
1985-01-01
The (He 1) photoelectron spectra of α=, β-, γ-vinyl, α-, β-, and γ-(1-dimethylvinyl)-pyridines, 1-dimethyl- and 1-diethylaminostyrenes were obtained and interpreted within the framework of the molecular orbital perturbation theory. In both pyridine derivative series, there is a regular increase in the ionization energy of the 1α 2 , π/sub C=C/ and n/sub en/ orbitals and decrease in the ionization energy of the 2b 1 orbitals in the order α 2 and 2b 1 is found for γ-vinylpyridine). The splitting of the energy levels of the heterocycle in dimethylaminovinylpyridines is less than in the corresponding vinyl derivatives, which indicates a weakening of the interaction between the aromatic (or heteroaromatic) ring and the enamine fragment extruding from the ring plane. The ionization energy of the unshared electron pair of the nitrogen atom of the pyridine ring for all the compounds except for α- (1-dimethylaminovinyl)pyridine (which displays an ortho effect) is close to that for pyridine. The photoelectron spectral data are compared with the MO energies calculated by the MINDO/3 method
13. Pyridine 2,4-dicarboxylic acid suppresses tomato seedling growth
Science.gov (United States)
Fragkostefanakis, Sotirios; Kaloudas, Dimitrios; Kalaitzis, Panagiotis
2018-01-01
Pyridine 2,4-dicarboxylic acid is a structural analogue of 2-oxoglutarate and is known to inhibit 2-oxoglutare-dependent dioxygenases. The effect of this inhibitor in tomato seedlings grown in MS media supplied with various concentrations of PDCA was investigated, resulting in shorter roots and hypocotyls in a dose-dependent manner. The partial inhibition of growth in roots was more drastic compared to hypocotyls and was attributed to a decrease in the elongation of root and hypocotyl cells. Concentrations of 100 and 250 μΜ of PDCA decreased hydroxyproline content in roots while only the 250 μΜ treatment reduced the hydroxyproline content in shoots. Seedlings treated with 100 μΜ PDCA exhibited enhanced growth of hypocotyl and cotyledon cells and higher hydroxyproline content resulting in cotyledons with greater surface area. However, no alterations in hypocotyl length were observed. Prolyl 4 hydroxylases (P4Hs) are involved in the O-glycosylation of AGPs and were also highly expressed during seedling growth. Moreover PDCA induced a decrease in the accumulation of HRGPs and particularly in AGPs-bound epitopes in a dose dependent-manner while more drastic reduction were observed in roots compared to shoots. In addition, bulged root epidermal cells were observed at the high concentration of 250 μΜ which is characteristic of root tissues with glycosylation defects. These results indicate that PDCA induced pleiotropic effects during seedling growth while further studies are required to better investigate the physiological significance of this 2-oxoglutarate analogue. This pharmacological approach might be used as a tool to better understand the physiological significance of HRGPs and probably P4Hs in various growth and developmental programs in plants.
14. Pyridine 2,4-Dicarboxylic Acid Suppresses Tomato Seedling Growth
Directory of Open Access Journals (Sweden)
Sotirios Fragkostefanakis
2018-01-01
Full Text Available Pyridine 2,4-dicarboxylic acid is a structural analog of 2-oxoglutarate and is known to inhibit 2-oxoglutare-dependent dioxygenases. The effect of this inhibitor in tomato seedlings grown in MS media supplied with various concentrations of PDCA was investigated, resulting in shorter roots and hypocotyls in a dose-dependent manner. The partial inhibition of growth in roots was more drastic compared to hypocotyls and was attributed to a decrease in the elongation of root and hypocotyl cells. Concentrations of 100 and 250 μM of PDCA decreased hydroxyproline content in roots while only the 250 μM treatment reduced the hydroxyproline content in shoots. Seedlings treated with 100 μM PDCA exhibited enhanced growth of hypocotyl and cotyledon cells and higher hydroxyproline content resulting in cotyledons with greater surface area. However, no alterations in hypocotyl length were observed. Prolyl 4 hydroxylases (P4Hs are involved in the O-glycosylation of AGPs and were also highly expressed during seedling growth. Moreover PDCA induced a decrease in the accumulation of HRGPs and particularly in AGPs-bound epitopes in a dose dependent-manner while more drastic reduction were observed in roots compared to shoots. In addition, bulged root epidermal cells were observed at the high concentration of 250 μM which is characteristic of root tissues with glycosylation defects. These results indicate that PDCA induced pleiotropic effects during seedling growth while further studies are required to better investigate the physiological significance of this 2-oxoglutarate analog. This pharmacological approach might be used as a tool to better understand the physiological significance of HRGPs and probably P4Hs in various growth and developmental programs in plants.
15. Binary and ternary cocrystals of sulfa drug acetazolamide with pyridine carboxamides and cyclic amides.
Science.gov (United States)
Bolla, Geetha; Nangia, Ashwini
2016-03-01
A novel design strategy for cocrystals of a sulfonamide drug with pyridine carboxamides and cyclic amides is developed based on synthon identification as well as size and shape match of coformers. Binary adducts of acetazolamide (ACZ) with lactams (valerolactam and caprolactam, VLM, CPR), cyclic amides (2-pyridone, labeled as 2HP and its derivatives MeHP, OMeHP) and pyridine amides (nicotinamide and picolinamide, NAM, PAM) were obtained by manual grinding, and their single crystals by solution crystallization. The heterosynthons in the binary cocrystals of ACZ with these coformers suggested a ternary combination for ACZ with pyridone and nicotinamide. Novel supramolecular synthons of ACZ with lactams and pyridine carboxamides are reported together with binary and ternary cocrystals for a sulfonamide drug. This crystal engineering study resulted in the first ternary cocrystal of acetazolamide with amide coformers, ACZ-NAM-2HP (1:1:1).
16. Binary and ternary cocrystals of sulfa drug acetazolamide with pyridine carboxamides and cyclic amides
Directory of Open Access Journals (Sweden)
Geetha Bolla
2016-03-01
Full Text Available A novel design strategy for cocrystals of a sulfonamide drug with pyridine carboxamides and cyclic amides is developed based on synthon identification as well as size and shape match of coformers. Binary adducts of acetazolamide (ACZ with lactams (valerolactam and caprolactam, VLM, CPR, cyclic amides (2-pyridone, labeled as 2HP and its derivatives MeHP, OMeHP and pyridine amides (nicotinamide and picolinamide, NAM, PAM were obtained by manual grinding, and their single crystals by solution crystallization. The heterosynthons in the binary cocrystals of ACZ with these coformers suggested a ternary combination for ACZ with pyridone and nicotinamide. Novel supramolecular synthons of ACZ with lactams and pyridine carboxamides are reported together with binary and ternary cocrystals for a sulfonamide drug. This crystal engineering study resulted in the first ternary cocrystal of acetazolamide with amide coformers, ACZ–NAM–2HP (1:1:1.
17. Copper-catalyzed aerobic oxidative C-H functionalization of substituted pyridines: synthesis of imidazopyridine derivatives.
Science.gov (United States)
Yu, Jipan; Jin, Yunhe; Zhang, Hao; Yang, Xiaobo; Fu, Hua
2013-12-02
A novel, efficient, and practical method for the synthesis of imidazopyridine derivatives has been developed through the copper-catalyzed aerobic oxidative C-H functionalization of substituted pyridines with N-(alkylidene)-4H-1,2,4-triazol-4-amines. The procedure occurs by cleavage of the N-N bond in the N-(alkylidene)-4H-1,2,4-triazol-4-amines and activation of an aryl C-H bond in the substituted pyridines. This is the first example of the preparation of imidazopyridine derivatives by using pyridines as the substrates by transition-metal-catalyzed C-H functionalization. This method should provide a novel and efficient strategy for the synthesis of other nitrogen heterocycles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
18. pH-responsive fluorescence chemical sensor constituted by conjugated polymers containing pyridine rings.
Science.gov (United States)
Adachi, Naoya; Kaneko, Yuki; Sekiguchi, Kazuki; Sugiyama, Hiroki; Sugeno, Masafumi
2015-12-01
Poly(p-pyridinium phenylene ethynylene)s (PPyPE) functionalized with alternating donor-acceptor repeat units were synthesized by a Pd-catalyzed Sonogashira coupling reaction between diethynyl monomer and di-iodopyridine for use as a pH-responsive fluorescence chemical sensor. The synthesized PPyPE, containing pyridine units, was characterized by FT-IR, (1)H and (13)C NMR, UV-visible and fluorescence spectroscopies. We investigated the relationship between changes of optical properties and protonation/deprotonation of PPyPE containing pyridine units in solution. Addition of HCl decreased and red-shifted the fluorescence intensity of the conjugated polymers that contained pyridine rings; fluorescence intensity of the polymers increased upon addition of NaOH solution. The synthesized PPyPE was found to be an effective and reusable chemical sensor for pH sensing. Copyright © 2015 John Wiley & Sons, Ltd.
19. Spin crossover and high spin filtering behavior in Co-Pyridine and Co-Pyrimidine molecules
Science.gov (United States)
Wen, Zhongqian; Zhou, Liping; Cheng, Jue-Fei; Li, Shu-Jin; You, Wen-Long; Wang, Xuefeng
2018-03-01
We present a theoretical study on a series of cobalt complexes, which are constructed with cobalt atoms and pyridine/pyrimidine rings, using density functional theory. We investigate the structural and electric transport properties of spin crossover (SCO) Co complex with two spin states, namely low-spin configuration [LS] and high-spin configuration [HS]. Energy analyses of the two spin states imply that the SCO Co-Pyridine2 and Co-Pyrimidine2 complexes may display a spin transition process accompanied by a geometric modification driven by external stimuli. A nearly perfect spin filtering effect is observed in the Co-Pyrimidine2 complex with [HS] state. In addition, we also discover the contact-dependent transmission properties of Co-Pyridine2. These findings indicate that SCO Co complexes are promising materials for molecular spintronic devices.
20. Carbon dioxide is tightly bound in the [Co(Pyridine)(CO2)](-) anionic complex.
Science.gov (United States)
Graham, Jacob D; Buytendyk, Allyson M; Zhang, Xinxing; Kim, Seong K; Bowen, Kit H
2015-11-14
The [Co(Pyridine)(CO2)](-) anionic complex was studied through the combination of photoelectron spectroscopy and density functional theory calculations. This complex was envisioned as a primitive model system for studying CO2 binding to negatively charged sites in metal organic frameworks. The vertical detachment energy (VDE) measured via the photoelectron spectrum is 2.7 eV. Our calculations imply a structure for [Co(Pyridine)(CO2)](-) in which a central cobalt atom is bound to pyridine and CO2 moieties on either sides. This structure was validated by acceptable agreement between the calculated and measured VDE values. Based on our calculations, we found CO2 to be bound within the anionic complex by 1.4 eV.
1. Carbon dioxide is tightly bound in the [Co(Pyridine)(CO2)]- anionic complex
Science.gov (United States)
Graham, Jacob D.; Buytendyk, Allyson M.; Zhang, Xinxing; Kim, Seong K.; Bowen, Kit H.
2015-11-01
The [Co(Pyridine)(CO2)]- anionic complex was studied through the combination of photoelectron spectroscopy and density functional theory calculations. This complex was envisioned as a primitive model system for studying CO2 binding to negatively charged sites in metal organic frameworks. The vertical detachment energy (VDE) measured via the photoelectron spectrum is 2.7 eV. Our calculations imply a structure for [Co(Pyridine)(CO2)]- in which a central cobalt atom is bound to pyridine and CO2 moieties on either sides. This structure was validated by acceptable agreement between the calculated and measured VDE values. Based on our calculations, we found CO2 to be bound within the anionic complex by 1.4 eV.
2. SAR studies directed toward the pyridine moiety of the sap-feeding insecticide sulfoxaflor (Isoclast™ active).
Science.gov (United States)
Loso, Michael R; Benko, Zoltan; Buysse, Ann; Johnson, Timothy C; Nugent, Benjamin M; Rogers, Richard B; Sparks, Thomas C; Wang, Nick X; Watson, Gerald B; Zhu, Yuanming
2016-02-01
Sap-feeding insect pests constitute a major insect pest complex that includes a range of aphids, whiteflies, planthoppers and other insect species. Sulfoxaflor (Isoclast™ active), a new sulfoximine class insecticide, targets sap-feeding insect pests including those resistant to many other classes of insecticides. A structure activity relationship (SAR) investigation of the sulfoximine insecticides revealed the importance of a 3-pyridyl ring and a methyl substituent on the methylene bridge linking the pyridine and the sulfoximine moiety to achieving strong Myzus persicae activity. A more in depth QSAR investigation of pyridine ring substituents revealed a strong correlation with the calculated logoctanol/water partition coefficient (SlogP). Model development resulted in a highly predictive model for a set of 18 sulfoximines including sulfoxaflor. The model is consistent with and helps explain the highly optimized pyridine substitution pattern for sulfoxaflor. Copyright © 2015 Elsevier Ltd. All rights reserved.
3. A simple and efficient synthesis of imidazolo[1,2-a]pyridines using MgO in aqueous medium
Directory of Open Access Journals (Sweden)
S.V. Patil
2016-11-01
Full Text Available Various imidazolo[1,2-a]pyridines were synthesized from amino pyridines and aromatic phenacyl bromides by one step process in the presence of MgO in aqueous medium at room temperature. The salient feature of this method includes mild conditions, short reaction time, high yields, easy purification and simple procedure.
4. Solid-State Examination of Conformationally Diverse Sulfonamide Receptors Based on Bis(2-anilinoethynyl)pyridine, -Bipyridine, and -Thiophene.
Science.gov (United States)
Berryman, Orion B; Johnson, Charles A; Vonnegut, Chris L; Fajardo, Kevin A; Zakharov, Lev N; Johnson, Darren W; Haley, Michael M
2015-03-04
Utilizing an induced-fit model and taking advantage of rotatable acetylenic C(sp)-C(sp 2 ) bonds, we disclose the synthesis and solid-state structures of a series of conformationally diverse bis-sulfonamide arylethynyl receptors using either pyridine, 2,2'-bipyridine, or thiophene as the core aryl group. Whereas the bipyridine and thiophene structures do not appear to bind guests in the solid state, the pyridine receptors form 2 + 2 dimers with water molecules, two halides, or one of each, depending on the protonation state of the pyridine nitrogen atom. Isolation of a related bis-sulfonimide derivative demonstrates the importance of the sulfonamide N-H hydrogen bonds in dimer formation. The pyridine receptors form monomeric structures with larger guests such as BF 4 - or HSO 4 - , where the sulfonamide arms rotate to the side opposite the pyridine N atom.
5. Solid-State Examination of Conformationally Diverse Sulfonamide Receptors Based on Bis(2-anilinoethynyl)pyridine, -Bipyridine, and -Thiophene
Science.gov (United States)
Berryman, Orion B.; Johnson, Charles A.; Vonnegut, Chris L.; Fajardo, Kevin A.; Zakharov, Lev N.; Johnson, Darren W.; Haley, Michael M.
2015-01-01
Utilizing an induced-fit model and taking advantage of rotatable acetylenic C(sp)–C(sp2) bonds, we disclose the synthesis and solid-state structures of a series of conformationally diverse bis-sulfonamide arylethynyl receptors using either pyridine, 2,2′-bipyridine, or thiophene as the core aryl group. Whereas the bipyridine and thiophene structures do not appear to bind guests in the solid state, the pyridine receptors form 2 + 2 dimers with water molecules, two halides, or one of each, depending on the protonation state of the pyridine nitrogen atom. Isolation of a related bis-sulfonimide derivative demonstrates the importance of the sulfonamide N–H hydrogen bonds in dimer formation. The pyridine receptors form monomeric structures with larger guests such as BF4− or HSO4−, where the sulfonamide arms rotate to the side opposite the pyridine N atom. PMID:26405435
6. Preparation of poly (vinyl alcohol) membranes grafted with n-vinyl pyridine/ acrylic acid binary monomers
International Nuclear Information System (INIS)
Ajji, A.; Ali, A.
2014-03-01
Poly(vinyl alcohol) films were grafted with two monomers using gamma radiation, acrylic acid and N-vinyl pyridine. The influence of different parameters on the grafting yield was investigated as: the comonomer concentration and composition, and irradiation dose. The suitable conditions of the process had been determined to prepare PVA membranes have both properties of the two monomers, acrylic acid and vinyl pyridine as comonomer concentration and composition, and irradiation dose. Some properties of the membranes had been investigated as maximum swelling and grafting. Also the ability of the grafted films to adsorb some heavy metals and dyes was elaborated and discussed.(author)
7. One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor
Directory of Open Access Journals (Sweden)
Mark C. Bagley
2013-09-01
Full Text Available The Bohlmann–Rahtz pyridine synthesis and the Hantzsch dihydropyridine synthesis can be carried out in a microwave flow reactor or using a conductive heating flow platform for the continuous processing of material. In the Bohlmann–Rahtz reaction, the use of a Brønsted acid catalyst allows Michael addition and cyclodehydration to be carried out in a single step without isolation of intermediates to give the corresponding trisubstituted pyridine as a single regioisomer in good yield. Furthermore, 3-substituted propargyl aldehydes undergo Hantzsch dihydropyridine synthesis in preference to Bohlmann–Rahtz reaction in a very high yielding process that is readily transferred to continuous flow processing.
8. 8-Hydroxy-2-methylquinolinium tetrachlorido(pyridine-2-carboxylato-κ2N,Ostannate(IV
Directory of Open Access Journals (Sweden)
Ezzatollah Najafi
2011-02-01
Full Text Available In the reaction of pyridine-2-carboxylic acid and stannic chloride in the presence of 2-methyl-8-hydroxyquinoline, the 2-methyl-8-hydroxyquinoline is protonated, yielding the title salt, (C10H10NO[SnCl4(C6H4NO2]. The SnIV atom in the anion is N,O-chelated by a pyridine-2-carboxylate in a cis-SnNOCl4 octahedral geometry. The cation is linked to the anion by an O—H...O hydrogen bond.
9. trans-Dichloridobis(3,4-dimethylpyridine)platinum(II)
Science.gov (United States)
Chernyshev, Alexander N.; Bokach, Nadezhda A.; Izotova, Youlia A.; Haukka, Matti
2009-01-01
In the title compound, trans-[PtCl2(C7H9N)2], the PtII atom is located on an inversion center and is coordinated by two 3,4-dimethylpyridine ligands and two chloride ligands, resulting in a typical slightly distorted square-planar geometry. The crystallographic inversion centre forces the value of the C—N—N—C torsion angle to be linear and the 3,4-dimethyl-pyridine ligands to be coplanar. PMID:21581530
10. Reaction of the diimine pyridine ligand with aluminum alkyls: An unexpectedly complex reaction
NARCIS (Netherlands)
Knijnenburg, Q.; Smits, J.M.M.; Budzelaar, P.H.M.
2006-01-01
The diimine pyridine ligand 2,6-{2,6-(Pr2C6H3N)-Pr-i=CMe}(2)C5H3N (1) was reacted with a series of aluminum alkyls (Me3Al, Et3Al, (Bu3Al)-Bu-i, (Bu2AlH)-Bu-i, Et2AlCl). Depending on the choice of alkyl, addition to the imine carbon and the pyridine C2 and C4 positions was observed. Addition to C2
11. Synthesis, antimicrobial and cytotoxic activities of 5-benzylidene-2-[(pyridine-4-ylmethylenehydrazono]-thiazolidin-4-one and 2-[(pyridine-4-ylmethylene hydrazono]-thiazolidin-4-one derivatives
Directory of Open Access Journals (Sweden)
Danniel Delmondes Feitoza
2012-01-01
Full Text Available A new series of 5-benzylidene-2-[(pyridine-4-ylmethylenehydrazono]-thiazolidin-4-ones 4a-l have been synthesized. These compounds were designed by a molecular hybridization approach. 2-[(Pyridine-4-ylmethylenehydrazono]-thiazolidin-4-ones 3a-d were also obtained and used as intermediates to give the target compounds. The in vitro antimicrobial and cytotoxic activities were evaluated for both series. The intermediate 3b showed considerable antibiotic activity against B. subtilis and C. albicans. In the cytotoxic activity compounds 3b (IC50= 4.25 ± 0.36 µg/mL and 4l (IC50= 1.38 ± 0.04 µg/mL were effective for inhibition of human erythromyeloblastoid leukemia (K-562 and human lung carcinoma (NCI-H292 cell lines, respectively.
12. Synthesis, antimicrobial and cytotoxic activities of 5-benzylidene-2-[(pyridine-4-ylmethylene)hydrazono]-thiazolidin-4-one and 2-[(pyridine-4-ylmethylene) hydrazono]-thiazolidin-4-one derivatives
Energy Technology Data Exchange (ETDEWEB)
Feitoza, Danniel Delmondes; Alves, Antonio Jose; Lima, Jose Gildo de, E-mail: [email protected] [Departamento de Ciencias Farmaceuticas, Universidade Federal de Pernambuco, Recife - PE (Brazil); Araujo, Janete Magali; Aguiar, Jaciana Santos; Rodrigues, Maria do Desterro; Silva, Teresinha Goncalves; Nascimento, Silene Carneiro do; Goes, Alexandre Jose da Silva [Departamento de Antibioticos, Universidade Federal de Pernambuco, Recife - PE (Brazil)
2012-07-01
A new series of 5-benzylidene-2-[(pyridine-4-ylmethylene)hydrazono]-thiazolidin-4-ones 4a-l have been synthesized. These compounds were designed by a molecular hybridization approach. 2-[(Pyridine-4-ylmethylene)hydrazono]-thiazolidin-4-ones 3a-d were also obtained and used as intermediates to give the target compounds. The in vitro antimicrobial and cytotoxic activities were evaluated for both series. The intermediate 3b showed considerable antibiotic activity against B. subtilis and C. albicans. In the cytotoxic activity compounds 3b (IC{sub 50} = 4.25 +- 0.36 {mu}g/mL) and 4l (IC{sub 50} = 1.38 +- 0.04 {mu}g/mL) were effective for inhibition of human erythromyeloblastoid leukemia (K-562) and human lung carcinoma (NCI-H292) cell lines, respectively. (author)
13. 2-[1-(1-Naphthyl-1H-1,2,3-triazol-4-yl]pyridine
Directory of Open Access Journals (Sweden)
Ulrich S. Schubert
2009-05-01
Full Text Available In the crystal structure of the title compound, C17H12N4, the angle between the naphthalene and 1H-1,2,3-triazole ring systems is 71.02 (4° and that between the pyridine and triazole rings is 8.30 (9°.
14. 2-(4-Methylpiperazin-1-yl-4-phenyl-6-(thiophen-2-yl-pyridine-3-carbonitrile
Directory of Open Access Journals (Sweden)
Nawal Mishriky
2013-02-01
Full Text Available 2-(4-Methylpiperazin-1-yl-4-phenyl-6-(thiophen-2-yl-pyridine-3-carbonitrile (4 was synthesized via nucleophilic substitution reaction of 1-methylpiperazine with 2-bromo analogue 3. The latter was obtained through bromination (Br2/AcOH of 2-[3-oxo-1-phenyl-3-(thiophen-2-ylpropyl]malononitrile (2.
15. Hydrogen trapping ability of the pyridine-lithium⁺ (1:1) complex.
Science.gov (United States)
Chattaraj, Saparya; Srinivasu, K; Mondal, Sukanta; Ghosh, Swapan K
2015-03-26
Theoretical studies have been carried out at different levels of theory to verify the hydrogen adsorption characteristics of pyridine-lithium ion (1:1) complexes. The nature of interactions associated with the bonding between pyridine and lithium as well as that between lithium and adsorbed molecular hydrogen is studied through the calculation of electron density and electron-density-based reactivity descriptors. The pyridine-lithium ion complex has been hydrogenated systematically around the lithium site, and each lithium site is found to adsorb a maximum of four hydrogen molecules with an interaction energy of ∼-4.0 kcal/mol per molecule of H2. The fate of the hydrogen adsorbed in a pyridine-lithium ion complex (corresponding to the maximum adsorption) is studied in the course of a 2 ps time evolution through ab initio molecular dynamics simulation at different temperatures. The results reveal that the complex can hold a maximum of four hydrogen molecules at a temperature of 77 K, whereas it can hold only two molecules of hydrogen at 298 K.
16. Design, synthesis and characterization of 1H-pyridin-4-yl-3,5 ...
Keywords. 1H-pyridin-4-yl-3,5-disubstituted indazoles; Suzuki reaction; Akt kinase activity. 1. Introduction. In organic synthesis, Palladium-catalysed new carbon– carbon bond formation from aryl halides with organo boronic acids via Suzuki coupling reaction has been proved to be an important method. The 2010 Nobel.
17. Lead optimization of a pyridine-carboxamide series as DGAT-1 inhibitors.
Science.gov (United States)
Ting, Pauline C; Lee, Joe F; Zorn, Nicolas; Kim, Hyunjin M; Aslanian, Robert G; Lin, Mingxiang; Smith, Michelle; Walker, Scott S; Cook, John; Van Heek, Margaret; Lachowicz, Jean
2013-02-15
The structure-activity relationship studies of a novel series of carboxylic acid derivatives of pyridine-carboxamides as DGAT-1 inhibitors is described. The optimization of the initial lead compound 6 based on in vitro and in vivo activity led to the discovery of key compounds 10j and 17h. Copyright © 2013 Elsevier Ltd. All rights reserved.
18. The synthesis of N-Zn, N-Cu complexes involving 2-amino pyridine ...
amino pyridine and ethylenediamine ligands (1a-b and 2a-b) have been described. They were synthesized with a simple, one-pot method, and the crystal structures of 1a, 1b, 2a and 2b were determined by X-ray crystallography. The complexes ...
19. Unprecedentedly mild direct Pd-catalyzed arylation of oxazolo[4,5-b]pyridine
DEFF Research Database (Denmark)
Zhuravlev, Fedor
2006-01-01
Pd-catalyzed C-2 arylation of oxazolo[4,5-b]pyridine proceeds efficiently at 30 degrees C and tolerates a variety of aryl halides, including derivatized amino acids for which no racemization was observed during the reaction. Experimental evidence for facile deprotonation of oxazolo[4,5-b...
20. Multicomponent ternary cocrystals of the sulfonamide group with pyridine-amides and lactams.
Science.gov (United States)
Bolla, Geetha; Nangia, Ashwini
2015-11-04
SMBA was selected as a bifunctional sulfa drug to design ternary cocrystals with pyridine amides and lactam coformers. Supramolecular assembly of five ternary cocrystals of p-sulfonamide benzoic acid with nicotinamide and 2-pyridone is demonstrated and reproducible heterosynthons are identified for crystal engineering.
1. Pyridine nucleotides in regulation of cell death and survival by redox and non-redox reactions.
Science.gov (United States)
Novak Kujundžić, Renata; Žarković, Neven; Gall Trošelj, Koraljka
2014-01-01
Changes of the level and ratios of pyridine nucleotides determine metabolism- dependent cellular redox status and the activity of poly(ADP-ribose) polymerases (PARPs) and sirtuins, thereby influencing several processes closely related to cell survival and death. Pyridine nucleotides participate in numerous metabolic reactions whereby their net cellular level remains constant, but the ratios of NAD+/NADP+ and NADH/NADPH oscillate according to metabolic changes in response to diverse stress signals. In non-redox reactions, NAD+ is degraded and quickly, afterward, resynthesized in the NAD+ salvage pathway, unless overwhelming activation of PARP-1 consumes NAD+ to the point of no return, when the cell can no longer generate enough ATP to accommodate NAD+ resynthesis. The activity of PARP-1 is mandatory for the onset of cytoprotective autophagy on sublethal stress signals. It has become increasingly clear that redox status, largely influenced by the metabolism-dependent composition of the pyridine nucleotides pool, plays an important role in the synthesis of pro-apoptotic and anti-apoptotic sphingolipids. Awareness of the involvement of the prosurvival sphingolipid, sphingosine-1-phosphate, in transition from inflammation to malignant transformation has recently emerged. Here, the participation of pyridine nucleotides in redox and non-redox reactions, sphingolipid metabolism, and their role in cell fate decisions is reviewed.
2. Hydroxyl pyridine containing polybenzimidazole membranes for proton exchange membrane fuel cells
DEFF Research Database (Denmark)
Yang, Jingshuai; Xu, Yixin; Zhou, Lu
2013-01-01
A polybenzimidazole variant polymer containing hydroxyl pyridine groups, termed as OHPyPBI, was synthesized from 3,3'-diaminobenzidine tetrahydrochloride and 4-hydroxy-2,6-pyridinedicarboxylic acid. The thermal-oxidative stability of the OHPyPBI polymer was as high as that of poly[2,2'-(m-phenyle...
3. Enhancement of the stimulated Raman scattering of benzene, acetonitrile and pyridine
International Nuclear Information System (INIS)
Munoz, L; Contreras, W A; Cabanzo, R; Aya-RamIrez, O; Mejia-Ospino, E
2011-01-01
In this work we used the second harmonic of Nd:YAG laser to observe stimulated Raman scattering (SRS). SRS was observed on benzene, acetonitrile and pyridine using a single shot laser. The SRS radiation is very intense due their laser characteristics, and it is possible to observe several harmonics of different vibrational modes to each molecule studied here.
4. Bohlmann-Rahtz Cyclodehydration of Aminodienones to Pyridines Using N-Iodosuccinimide
Directory of Open Access Journals (Sweden)
Mark C. Bagley
2010-04-01
Full Text Available Cyclodehydration of Bohlmann-Rahtz aminodienone intermediates using N-iodosuccinimide as a Lewis acid proceeds at low temperature under very mild conditions to give the corresponding 2,3,6-trisubstituted pyridines in high yield and with total regiocontrol.
5. Formation of pyridine N-oxides using mesoporous titanium silicalite-1
DEFF Research Database (Denmark)
Mielby, Jerrik Jørgen; Abildstrøm, Jacob Oskar; Perez-Ferreras, Susana
2014-01-01
Mesoporous titanium silicalite-1 (TS-1) prepared by carbon-templating is significantly more active than conventional TS-1 for the oxidation of pyridine derivatives using aqueous hydrogen peroxide as oxidant. The catalytic activity is increased by the system of mesopores that helps to overcome the...
6. Suitability of hardwood treated with phenoxy and pyridine herbicides for firewood use
Science.gov (United States)
P.B. Bush; D.G. Neary; Charles K. McMahon; J.W. Taylor
1987-01-01
Abstract. Potential exposure to pesticide residues resulting from burning wood treated with phenoxyand pyridine herbicides was assessed. Wood samples from trees treated with 2,4-D [2,4-dichlo-rophenoxy acetic acid], dicamba [3,6-dichloro-o-anisic acid], dichlorprop [2-(2,4-dichlorphenoxy) propionic acid], picloram [4-amino-3,5,dtrichloropico-linic...
7. The synthesis of a pyridine-: N -oxide isophthalamide rotaxane utilizing supplementary amide hydrogen bond interactions
OpenAIRE
Evans, Nicholas Henley; Gell, Charlie; Peach, Michael Joseph George
2016-01-01
The synthesis of a pyridine-N-oxide containing rotaxane, not requiring an additional ionic template, has been achieved in 32% yield. Successful rotaxane formation is dependent upon the structure of the isophthalamide macrocycle used, an observation which has been rationalised by a combination of NMR spectroscopy, X-ray crystallography and computational modelling.
8. Reaction of Titanocene Alkyls with Pyridines; A Novel Type of Cyclometallation Reaction
NARCIS (Netherlands)
Klei, E.; Teuben, J.H.
1981-01-01
Reaction of Cp2TiR (R = alkyl) with 2-substituted-pyridines and with quinolines leads to α-metallation of these ligands with formation of triangular titanocycles containing TiIII. Proof of the metallation at the α-position comes from reactions of the complexes formed with I2 and D2O/DCl which yield
9. Crystal structure of the pyridine-diiodine (1/1) adduct.
Science.gov (United States)
Tuikka, Matti; Haukka, Matti
2015-07-01
In the title adduct, C5H5N·I2, the N-I distance [2.424 (8) Å] is remarkably shorter than the sum of the van der Waals radii. The line through the I atoms forms an angle of 78.39 (16)° with the normal to the pyridine ring.
10. Some thiocyanato complexes of cadmium(II) with substituted pyridines and imidazoles
Energy Technology Data Exchange (ETDEWEB)
Mishra, B P; Ramana Rao, D V [Regional Engineering Coll., Rourkela (India). Dept. of Chemistry
1979-05-01
The complexes formed by cadmium(II) thiocyanate with 3-acetyl-, 3-bromo-, 3-methyl-, 4-acetyl-, 4-cyano-, 4-benzoyl pyridines, isoquinoline, 3,5-lutidine and imidazole, 2-methyl imidazole, 2-methyl benzimidazoles have been characterised through elemental analysis and molar conductance data. On the basis of infra-red spectroscopic studies, probable structures are discussed.
11. One-pot, three-component synthesis of highly substituted pyridines ...
trile in the presence of nanocrystalline magnesium oxide provides the highly substituted pyridine derivatives in moderate to ..... NAP–MgO (0⋅1 g), ethanol (5 mL) at reflux temperature b ... difference in the electronic and steric properties of.
12. 1,2-Bis (pyridin-2-ylmethyl)sulfanyl ethane and its dimorphic hydrochloride salt
DEFF Research Database (Denmark)
Lennartson, A.; McKenzie, C. J.
2011-01-01
and are held together by C-H center dot center dot center dot N and C-H center dot center dot center dot S interactions, resulting in the formation of a three-dimensional network structure. In addition, two polymorphs of the corresponding hydrochloride salt, 2-[(2-[(pyridin-1-ium-2-ylmethyl...
13. Technetium(I) complexes Tc(CO)3BrL2 (L = phosphine, pyridine, isocyanide)
International Nuclear Information System (INIS)
Lorenz, B.; Findeisen, M.; Olk, B.; Schmidt, K.
1988-01-01
Technetium pentacarbonyl bromide reacts with π-acceptor ligands L (L = phosphine, pyridine, isocyanide) to form disubstituted compounds of the type Tc(CO) 3 BrL 2 . The stereochemistry of the complexes was established by infrared and 1 H-NMR measurement. Chemical shifts and the half-widths of the 99 Tc-NMR signals are discussed. (author)
14. Kinetics of pyridine degradation along with toluene and methylene chloride with Bacillus sp. in packed bed reactor
Energy Technology Data Exchange (ETDEWEB)
Uma, B.; Sandhya, S. [National Environmental Engineering Research Institute, CSIR-Complex, Madras (India)
1998-04-01
Bacillus coagulans strain isolated from contaminated soil was immobilised on activated carbon for degradation of pyridine, toluene and methylene chloride containing synthetic wastewaters. Pyridine was supplied as the only source of nitrogen in the wastewaters. Continuous runs in a packed bed laboratory reactor showed that immobilized B. coagulans can degrade pyridine along with other organics rapidly and the effluent ammonia is also controlled in presence of organic carbon. About 644 mg/l of influent TOC was efficiently degraded (82.85%) at 64.05 mg/l/hr loading. (orig.) With 2 figs., 4 tabs., 15 refs.
15. Synthesis and Suzuki Cross-Coupling Reactions of 2,6-Bis(trifluoromethyl)pyridine-4-boronic Acid Pinacol Ester
KAUST Repository
Batool, Farhat
2016-11-18
Iridium-catalyzed aromatic borylation provides quick one-step access to 2,6-bis(trifluoromethyl)pyridine-4-boronic acid pinacol ester. Suzuki couplings of this highly electron-deficient pyridine-4-boronic ester with various (hetero)aryl bromides was successfully carried out and the coupled products were obtained in 46–95% isolated yields. Double and triple Suzuki couplings, with dibromo- and tribromoarenes, respectively, were also achieved. Thus demonstrating that this pyridine-4-boronic ester can be a useful source for the installation of one of the strongest electron-withdrawing aromatic group in organic compounds. Copyright © 2016, Georg Thieme Verlag. All rights reserved.
16. Synthesis and Suzuki Cross-Coupling Reactions of 2,6-Bis(trifluoromethyl)pyridine-4-boronic Acid Pinacol Ester
KAUST Repository
Batool, Farhat; Emwas, Abdul-Hamid M.; Gao, Xin; Munawar, Munawar A.; Chotana, Ghayoor A.
2016-01-01
Iridium-catalyzed aromatic borylation provides quick one-step access to 2,6-bis(trifluoromethyl)pyridine-4-boronic acid pinacol ester. Suzuki couplings of this highly electron-deficient pyridine-4-boronic ester with various (hetero)aryl bromides was successfully carried out and the coupled products were obtained in 46–95% isolated yields. Double and triple Suzuki couplings, with dibromo- and tribromoarenes, respectively, were also achieved. Thus demonstrating that this pyridine-4-boronic ester can be a useful source for the installation of one of the strongest electron-withdrawing aromatic group in organic compounds. Copyright © 2016, Georg Thieme Verlag. All rights reserved.
17. Co-polymer Films for Sensors
Science.gov (United States)
Ryan, Margaret A. (Inventor); Jewell, April D. (Inventor); Taylor, Charles (Inventor); Yen, Shiao-Pin S. (Inventor); Kisor, Adam (Inventor); Manatt, Kenneth S. (Inventor); Blanco, Mario (Inventor); Goddard, William A. (Inventor); Homer, Margie L. (Inventor); Shevade, Abhijit V. (Inventor)
2012-01-01
Embodiments include a sensor comprising a co-polymer, the co-polymer comprising a first monomer and a second monomer. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is polystyrene and the second monomer is poly-2-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium benzylamine chloride. Other embodiments are described and claimed.
18. Removal of pyridine and quinoline by bio-zeolite composed of mixed degrading bacteria and modified zeolite
International Nuclear Information System (INIS)
Bai Yaohui; Sun Qinghua; Xing Rui; Wen Donghui; Tang Xiaoyan
2010-01-01
In the process of the biodegradation of pyridine and quinoline, ammonium is often generated because of the transformation of N from pyridine and quinoline. Zeolite has been proven to be an effective sorbent for the removal of the ammonium. The natural zeolite can be modified to be the macroporous carrier in the biological wastewater treatment process. In this study, a specific bio-zeolite composed of mixed bacteria (a pyridine-degrading bacterium and a quinoline-degrading bacterium) and modified zeolite was used for biodegradation and adsorption in two types of wastewater: sterile synthetic and coking wastewater. The experimental results indicated that pyridine and quinoline could be degraded simultaneously by the mixed bacteria. Furthermore, NH 4 + -N transformed from pyridine and quinoline could be removed by the modified zeolite. In addition, the bacterial community structures of the coking wastewater and the bio-zeolite were monitored by the amplicon length heterogeneity polymerase-chain reaction (LH-PCR) technique. Both LH-PCR results and scanning electron microscope (SEM) observations indicated that the microorganisms, including BW001 and BW003, could be easily attached on the surface of the modified zeolite and that the bio-zeolite could be used in the treatment of wastewater containing pyridine and/or quinoline.
19. Novel semiconducting boron carbide/pyridine polymers for neutron detection at zero bias
Energy Technology Data Exchange (ETDEWEB)
Echeverria, Elena; Enders, A.; Dowben, P.A. [University of Nebraska-Lincoln, Department of Physics and Astronomy, Lincoln, NE (United States); James, Robinson; Chiluwal, Umesh; Gapfizi, Richard; Tae, Jae-Do; Driver, M. Sky; Kelber, Jeffry A. [University of North Texas, Department of Chemistry, Denton, TX (United States); Pasquale, Frank L. [University of North Texas, Department of Chemistry, Denton, TX (United States); Lam Research Corporation, PECVD Business Unit, Tualatin, OR (United States); Colon Santana, Juan A. [Center for Energy Sciences Research, Lincoln, NE (United States)
2014-09-19
Thin films containing aromatic pyridine moieties bonded to boron, in the partially dehydrogenated boron-rich icosahedra (B{sub 10}C{sub 2}H{sub X}), prove to be an effective material for neutron detection applications when deposited on n-doped (100) silicon substrates. The characteristic I-V curves for the heterojunction diodes exhibit strong rectification and largely unperturbed normalized reverse bias leakage currents with increasing pyridine content. The neutron capture generated pulses from these heterojunction diodes were obtained at zero bias voltage although without the signatures of complete electron-hole collection. These results suggest that modifications to boron carbide may result in better neutron voltaic materials. (orig.)
20. Adsorption behaviors of trivalent actinides and lanthanides on pyridine resin in lithium chloride aqueous solution
International Nuclear Information System (INIS)
Tatsuya Suzuki
2013-01-01
The adsorption behaviors of trivalent actinides and lanthanides on pyridine resin in lithium chloride aqueous solution were investigated. The adsorbed amounts of lanthanides and the degree of mutual separation of lanthanides increased with an increase in the concentration of lithium chloride in aqueous solution. The group separation of the trivalent actinides and lanthanides was observed. This separation phenomenon is similar in a hydrochloric acid solution. However, the adsorption behavior of lanthanides in lithium chloride is different from their behavior in a hydrochloric acid solution. This fact shows that the adsorption mechanisms of lanthanides in a lithium chloride aqueous solution and in a hydrochloric acid solution are different; the adsorption mechanisms are attributed to the ion exchange in a hydrochloric acid solution, and to the complex formation with pyridine group in a lithium chloride solution. (author)
1. Measurement and correlation of vapour pressures of pyridine and thiophene with [EMIM][SCN] ionic liquid
International Nuclear Information System (INIS)
Khelassi-Sefaoui, Asma; Mutelet, Fabrice; Mokbel, Ilham; Jose, Jacques; Negadi, Latifa
2014-01-01
Highlights: • VLE of (pyridine + [EMIM][SCN]), or (thiophene + [EMIM][SCN]) binary mixtures were measured. • The investigated temperatures are 273 K to 363 K. • The PC-SAFT equation of state has been used to correlate the vapour pressures of the binary systems. - Abstract: In this work (vapour + liquid) equilibrium (VLE) measurements were performed on binary systems of the ionic liquid 1-ethyl-3-methylimidazolium thiocynate [EMIM][SCN] with thiophene or pyridine at pressures close to the atmospheric pressure using a static device at temperatures between 273 K and 363 K. Experimental data were correlated by the PC-SAFT EoS. The binary interaction parameters k ij were optimised on experimental VLE data. The results obtained for the two binary mixtures studied in this paper indicate that the PC-SAFT EoS can be used to represent systems containing ionic liquids
2. Discovery of pyridine-based agrochemicals by using Intermediate Derivatization Methods.
Science.gov (United States)
Guan, Ai-Ying; Liu, Chang-Ling; Sun, Xu-Feng; Xie, Yong; Wang, Ming-An
2016-02-01
Pyridine-based compounds have been playing a crucial role as agrochemicals or pesticides including fungicides, insecticides/acaricides and herbicides, etc. Since most of the agrochemicals listed in the Pesticide Manual were discovered through screening programs that relied on trial-and-error testing and new agrochemical discovery is not benefiting as much from the in silico new chemical compound identification/discovery techniques used in pharmaceutical research, it has become more important to find new methods to enhance the efficiency of discovering novel lead compounds in the agrochemical field to shorten the time of research phases in order to meet changing market requirements. In this review, we selected 18 representative known agrochemicals containing a pyridine moiety and extrapolate their discovery from the perspective of Intermediate Derivatization Methods in the hope that this approach will have greater appeal to researchers engaged in the discovery of agrochemicals and/or pharmaceuticals. Copyright © 2015 Elsevier Ltd. All rights reserved.
3. 2,3-Diamino-pyridinium 6-carb-oxy-pyridine-2-carboxyl-ate.
Science.gov (United States)
Foroughian, Mahsa; Foroumadi, Alireza; Notash, Behrouz; Bruno, Giuseppe; Amiri Rudbari, Hadi; Aghabozorg, Hossein
2011-12-01
The asymmetric unit of the title proton-transfer compound, C(5)H(8)N(3) (+)·C(7)H(4)NO(4) (-), consists of one mono-deprotonated pyridine-2,6-dicarb-oxy-lic acid as anion and one protonated 2,3-diamino-pyridine as cation. The crystal packing shows extensive O-H⋯O, N-H⋯O and N-H⋯N hydrogen bonds. Thre are also several π-π inter-actions between the anions and also between the cations [centriod-centroid distances = 3.6634 (7), 3.7269 (7), 3.6705 (7) and 3.4164 (7) Å].
4. SYNTHESIS AND BIOLOGIC PROPERTIES OF SOME 1-(ALCHYLPHENYL-3-(4-(3-(PYRIDIN-2-ILACRYLOYLPHENYLTHIOUREA
Directory of Open Access Journals (Sweden)
A. Popusoi
2013-06-01
Full Text Available This paper describe the synthesis of some 1-(alchylaril-3-(4-(3-pyridin-2-il acryloylphenylthiourea obtained by condensation of 2-pyridincarboxaldehide with some derivatives of 4-acetylphenilthioureas in basic medium or by addition of aliphatic and aromatic amines to the correspondingisothiocyanatopropenones. 12 new compounds were obtained and their biological properties were analysed. The substituted thioureas by pyridine radicals, morpholine and phenol show a maximum bacteriostatic activity for Gram positive microorganisms like: Staphylococcus Aureus and Enterococcus Faecalis at the minimum inhibitory concentration 9.37-37.5 μM. Antifungal activity for Candida Albicans, Aspergillus Niger, AspergillusFumigatus, Penicillium is weak, in minimum inhibitory concentration 600->600 μM. The leukemia activity like inhibitor (HL-60, is 84-96.9% at the concentration 10-5mol/l and 15- 20% and at the concentrations 10-6, 10-7mol/l.
5. NHC Versus Pyridine: How “Teeth” Change the Redox Behavior of Iron(II) Complexes
KAUST Repository
Weiss, Daniel T.
2015-10-06
A series of octahedral iron(II) complexes with tetradentate NHC/pyridine hybrid ligands containing up to three pyridyl units was designed to study the influence of NHC and pyridine donors on the electronic structure of the metal center. Structural analysis of the iron complexes by NMR spectroscopy and single-crystal X-ray diffraction reveals different coordination modes of the ligand depending on the linkage of the different donor moieties. The oxidation potentials of all complexes correlate linearly with the number of NHC moieties coordinated to iron, as shown by cyclic voltammetry. The influence, although minor, of structural properties on the oxidation potential and (in one case) the influence of the oxidation state of the coordination geometry of the hybrid ligand are also demonstrated.
6. Synthesis, reactions, and antiarrhythmic activities of some novel pyrimidines and pyridines fused with thiophene moiety
OpenAIRE
AMR, Abdel-Galil El-Sayed; ABDEL-HAFEZ, Naglaa Abdel-Samei
2009-01-01
We report herein the synthesis and antiarrhythmic activities of some newly synthesized heterocyclic theino[2,3-c]pyrimidine and theino[2,3-c]pyridine derivatives fused with thiophene moiety. Initially the acute toxicity of the compounds was assayed via the determination of their LD50. The antiarrhythmic activities for the compounds were determined and all the tested compounds were found more potent than Procaine amide\\textregistered and Lidocaine\\textregistered as positive antiarrhyth...
7. Synthesis, reactions, and antiarrhythmic activities of some novel pyrimidines and pyridines fused with thiophene moiety
OpenAIRE
AMR, Abdel-Galil El-Sayed; ABDEL-HAFEZ, Naglaa Abdel-Samei; MOHAMED, Salwa Fahem; ABDALLA, Mohamed Mostafa
2014-01-01
We report herein the synthesis and antiarrhythmic activities of some newly synthesized heterocyclic theino[2,3-c]pyrimidine and theino[2,3-c]pyridine derivatives fused with thiophene moiety. Initially the acute toxicity of the compounds was assayed via the determination of their LD50. The antiarrhythmic activities for the compounds were determined and all the tested compounds were found more potent than Procaine amide\\textregistered and Lidocaine\\textregistered as positive antiarrhyth...
KAUST Repository
Winston, Matthew S.; Bercaw, John E.
2014-01-01
A series of complexes of the type (PNP-H2)PdX2 (X=Cl, Br, I) have been synthesized, where PNP-H2 is a bis(secondary)phosphine ligand linked by a pyridine, 2,6-(2'-(Ph(H)P)(C6H4))2(C5H3N). Due to chirality at phosphorus, the parent ligand exists as a
9. N,N-Diethyl-4-[(E-(pyridin-3-yldiazenyl]aniline
Directory of Open Access Journals (Sweden)
Tatiana V. Timofeeva
2013-08-01
Full Text Available The molecule of the title compound, C15H18N4, adopts a trans conformation with respect to the diazo N=N bond. The dihedral angle between the benzene and pyridine rings in the molecule is 8.03 (5°. In the crystal, a weak C—H...π interaction arranges the molecules into a corrugated ribbon, with an antiparallel orientation of neighboring molecules propagating in the [100] direction.
10. (E-4-Methoxy-3,5-dimethyl-2-[(3-nitrophenylethenyl]pyridine
Directory of Open Access Journals (Sweden)
Youness El Bakri
2016-12-01
Full Text Available In the crystal of the title compound, C16H16N2O3, weak C—H...O hydrogen bonds involving the nitro group as acceptor form chains extending in the b-axis direction. The chains are arranged into layers by π–π stacking interactions along the c-axis direction between the substituted pyridine rings, separated by 3.624 (1 Å.
11. Preparation and characterization of some pyridine-2,6-dicarboxylato thorium(IV) complexes
Energy Technology Data Exchange (ETDEWEB)
Degetto, S; Baracco, L [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi; Graziani, R [Padua Univ. (Italy). Istituto di Chimica Generale ed Inorganica; Celon, E [Padua Univ. (Italy). Istituto di Chimica Organica
1978-12-01
The preparation of complexes of pyridine-2,6-dicarboxylic acid (H/sub 2/PDC) with thorium(IV) is reported and discussed. The reactivity of Th(PDC)/sub 2/(H/sub 2/O)/sub 4/ was tested by preparing adducts with some neutral ligands. The complexes were characterized by i.r. spectroscopy, elemental analysis and thermal behaviour. Preliminary information on the structure obtained by x-ray analysis is also reported.
12. Thermodynamic study of complexation of thorium with pyridine monocarboxylates by calorimetry and DFT calculations
International Nuclear Information System (INIS)
Rama Mohana Rao, D.; Rawat, Neetika; Sawant, R.M.; Tomar, B.S.; Manna, D.; Ghanty, T.K.
2013-01-01
Stability constants of Th(IV) complexes with pyridine mono-carboxylates, namely, picolinate, nicotinate and isonicotinate have been determined following potentiometric titration of the metal ion and ligand mixtures with NaOH solution of known concentration. These data were used during the analysis of the calorimetric titration data to obtain the enthalpy of complexation reactions. The experimental data have been compared with that obtained from the DFT based theoretical calculations. (author)
13. Effective transport properties for the pyridine-granular activated carbon adsorption system
OpenAIRE
Baz-Rodríguez, S. A.; Ocampo-Pérez, R.; Ruelas-Leyva, J. P.; Aguilar-Madera, C. G.
2012-01-01
In this work, the kinetics of pyridine adsorption onto granular activated carbon was studied from the point of view of an up-scaling process by using the method of volume averaging. The pore and surface effective diffusivities were estimated by supposing simple microscale geometries (ordered media of cylinders and spheres) and those of images processed from SEM (Scanning Electron Microscopy) micrographs. In addition, as a rough estimate, the point surface diffusivity is reported. The results ...
14. Synthesis, Reactivity and Stability of Aryl Halide Protecting Groups towards Di-Substituted Pyridines
Directory of Open Access Journals (Sweden)
Ptoton Mnangat Brian
2016-03-01
Full Text Available This paper reports the synthesis and reactivity of different Benzyl derivative protecting groups. The synthesis and stability of Benzyl halides, 4-methoxybenzyl halides, 3,5-dimethoxybenzyl halides, 3,4-dimethoxybenzyl halides, 3,4,5-trimethoxybenzyl halide protecting groups and their reactivity towards nitrogen atom of a di-substituted pyridine ring in formation of pyridinium salts is also reported.
15. Pharmacological Potential and Synthetic Approaches of Imidazo[4,5-b]pyridine and Imidazo[4,5-c]pyridine Derivatives
Directory of Open Access Journals (Sweden)
Malwina Krause
2017-03-01
Full Text Available The structural resemblance between the fused imidazopyridine heterocyclic ring system and purines has prompted biological investigations to assess their potential therapeutic significance. They are known to play a crucial role in numerous disease conditions. The discovery of their first bioactivity as GABAA receptor positive allosteric modulators divulged their medicinal potential. Proton pump inhibitors, aromatase inhibitors, and NSAIDs were also found in this chemical group. Imidazopyridines have the ability to influence many cellular pathways necessary for the proper functioning of cancerous cells, pathogens, components of the immune system, enzymes involved in carbohydrate metabolism, etc. The collective results of biochemical and biophysical properties foregrounded their medicinal significance in central nervous system, digestive system, cancer, inflammation, etc. In recent years, new preparative methods for the synthesis of imidazopyridines using various catalysts have been described. The present manuscript to the best of our knowledge is the complete compilation on the synthesis and medicinal aspects of imidazo[4,5-b]pyridines and imidazo[4,5-c]pyridines reported from the year 2000 to date, including structure–activity relationships.
16. Aqua{2-(pyridin-2-yl-N-[(pyridin-2-ylmethylidene]ethanamine-κ3N,N′,N′′}(sulfato-κ2O,O′copper(II tetrahydrate
Directory of Open Access Journals (Sweden)
Daniel Tinguiano
2013-01-01
Full Text Available The title complex, [Cu(SO4(C13H13N3(H2O]·4H2O, was obtained by mixing copper sulfate pentahydrate and 2-(pyridin-2-yl-N-(pyridin-2-ylmethylideneethanamine in ethanol under reflux conditions. The CuII ion shows a Jahn–Teller-distorted octahedral geometry, with equatorial positions occupied by three N atoms from the tridentate ligand (average Cu—N = 2.004 Å and one O atom from a bidentate sulfate anion [Cu—O = 1.963 (2 Å]. The axial positions are occupied by one O atom from a coordinating water molecule [Cu—O = 2.230 (3 Å] and one weakly bonded O atom [Cu—O = 2.750 (2 Å] from the bidentate sulfate ion. The complex molecules are connected through O—H...O hydrogen bonds between the coordinating water molecules and sulfate ions from neighboring complexes, forming a double chain parallel to the c axis. The chains are stabilized through additional hydrogen bonds by one of the non-coordinating water molecules bridging between neighboring strands of the double chains. The remaining three water molecules fill the interstitial space between the double chains and are involved in an intricate hydrogen-bonding network that consolidates the structure.
17. Crystal structure of 2-hy-droxy-imino-2-(pyridin-2-yl)-N'-[1-(pyridin-2-yl)ethyl-idene]acetohydrazide.
Science.gov (United States)
Plutenko, Maxym O; Lampeka, Rostislav D; Haukka, Matti; Nordlander, Ebbe
2014-12-01
The mol-ecule of the title compound, C14H13N5O2, is approximately planar (r.m.s deviation for all non-H atoms = 0.093 Å), with the planes of the two pyridine rings inclined to one another by 5.51 (7)°. The oxime group is syn to the amide group, probably due to the formation of an intra-molecular N-H⋯N hydrogen bond that forms an S(6) ring motif. In the crystal, mol-ecules are linked by pairs of bifurcated O-H⋯(O,N) hydrogen bonds, forming inversion dimers. The latter are linked via C-H⋯O and C-H⋯N hydrogen bonds, forming sheets lying parallel to (502). The sheets are linked via π-π stacking inter-actions [inter-centroid distance = 3.7588 (9) Å], involving the pyridine rings of inversion-related mol-ecules, forming a three-dimensional structure.
18. Crystal structure of 2-hydroxyimino-2-(pyridin-2-yl)-N′-[1-(pyridin-2-yl)ethylidene]acetohydrazide
Science.gov (United States)
Plutenko, Maxym O.; Lampeka, Rostislav D.; Haukka, Matti; Nordlander, Ebbe
2014-01-01
The molecule of the title compound, C14H13N5O2, is approximately planar (r.m.s deviation for all non-H atoms = 0.093 Å), with the planes of the two pyridine rings inclined to one another by 5.51 (7)°. The oxime group is syn to the amide group, probably due to the formation of an intramolecular N—H⋯N hydrogen bond that forms an S(6) ring motif. In the crystal, molecules are linked by pairs of bifurcated O—H⋯(O,N) hydrogen bonds, forming inversion dimers. The latter are linked via C—H⋯O and C—H⋯N hydrogen bonds, forming sheets lying parallel to (502). The sheets are linked via π–π stacking interactions [inter-centroid distance = 3.7588 (9) Å], involving the pyridine rings of inversion-related molecules, forming a three-dimensional structure. PMID:25552998
19. Pharmacological Potential and Synthetic Approaches of Imidazo[4,5-b]pyridine and Imidazo[4,5-c]pyridine Derivatives.
Science.gov (United States)
Krause, Malwina; Foks, Henryk; Gobis, Katarzyna
2017-03-04
The structural resemblance between the fused imidazopyridine heterocyclic ring system and purines has prompted biological investigations to assess their potential therapeutic significance. They are known to play a crucial role in numerous disease conditions. The discovery of their first bioactivity as GABA A receptor positive allosteric modulators divulged their medicinal potential. Proton pump inhibitors, aromatase inhibitors, and NSAIDs were also found in this chemical group. Imidazopyridines have the ability to influence many cellular pathways necessary for the proper functioning of cancerous cells, pathogens, components of the immune system, enzymes involved in carbohydrate metabolism, etc. The collective results of biochemical and biophysical properties foregrounded their medicinal significance in central nervous system, digestive system, cancer, inflammation, etc. In recent years, new preparative methods for the synthesis of imidazopyridines using various catalysts have been described. The present manuscript to the best of our knowledge is the complete compilation on the synthesis and medicinal aspects of imidazo[4,5- b ]pyridines and imidazo[4,5- c ]pyridines reported from the year 2000 to date, including structure-activity relationships.
20. Structural and physicochemical characterization of pyridine derivative salts of anti-inflammatory drugs
Science.gov (United States)
Nechipadappu, Sunil Kumar; Trivedi, Darshak R.
2017-08-01
Salts of common anti-inflammatory drugs mefenamic acid (MFA), tolfenamic acid (TFA) and naproxen (NPX) with various pyridine derivatives (4-amino pyridine (4AP), 4-dimethylaminopyridine (DMAP) and 2-amino pyridine (2AP)) were synthesized by crystal engineering approach based on the pKa values of API's and the salt former. All the salts were characterized systematically by various spectroscopic methods including FT-IR and 1H NMR and the crystal structure was determined by single-crystal X-ray diffraction techniques (SCXRD). DMAP salt of NPX and 2AP salts of MFA and TFA were not obtained in the salt screening experiments. All the molecular salts exhibited 1:1 molecular stoichiometry in the asymmetric unit and except NPX-2AP salt, all the molecular salts included a water molecule in the crystal lattice. Physicochemical and structural properties between drug-drug molecular salts of MFA-4AP, TFA-4AP and NPX-4AP have been evaluated and it was found that these molecular salts were found to be stable for a time period of six months at ambient condition and further hydration of molecular salts were not observed even at accelerated humid conditions (∼75% RH). It was found that 4AP salts of MFA and TFA and DMAP salts of MFA and TFA are isostructural.
1. Fluorescent property of 3-hydroxymethyl imidazo[1,2-a]pyridine and pyrimidine derivatives
Directory of Open Access Journals (Sweden)
Velázquez-Olvera Stephania
2012-08-01
Full Text Available Abstract Background Imidazo[1,2-a]pyridines and pyrimidines are important organic fluorophores which have been investigated as biomarkers and photochemical sensors. The effect on the luminescent property by substituents in the heterocycle and phenyl rings, have been studied as well. In this investigation, series of 3-hydroxymethyl imidazo[1,2-a]pyridines and pyrimidines were synthesized and evaluated in relation to fluorescence emission, based upon the hypothesis that the hydroxymethyl group may act as an enhancer of fluorescence intensity. Results Compounds of both series emitted light in organic solvents dilutions as well as in acidic and alkaline media. Quantitative fluorescence spectroscopy determined that both fused heterocycles fluoresced more intensely than the parent unsubstituted imidazo[1,2-a]azine fluorophore. In particular, 3-hydroxymethyl imidazo[1,2-a]pyridines fluoresced more intensely than 3-hydroxymethyl imidazo[1,2-a]pyrimidines, the latter emitting blue light at longer wavelengths, whereas the former emitted purple light. Conclusion It was concluded that in most cases the hydroxymethyl moiety did act as an enhancer of the fluorescence intensity, however, a comparison made with the fluorescence emitted by 2-aryl imidazo[1,2-a]azines revealed that in some cases the hydroxymethyl substituent decreased the fluorescence intensity.
2. Enhanced Charge Separation Efficiency in Pyridine-Anchored Phthalocyanine-Sensitized Solar Cells by Linker Elongation.
Science.gov (United States)
Ikeuchi, Takuro; Agrawal, Saurabh; Ezoe, Masayuki; Mori, Shogo; Kimura, Mutsumi
2015-11-01
A series of zinc phthalocyanine sensitizers (PcS22-24) having a pyridine anchoring group are designed and synthesized to investigate the structural dependence on performance in dye-sensitized solar cells. The pyridine-anchor zinc phthalocyanine sensitizer PcS23 shows 79 % incident-photon to current-conversion efficiency (IPCE) and 6.1 % energy conversion efficiency, which are comparable with similar phthalocyanine dyes having a carboxylic acid anchoring group. Based on DFT calculations, the high IPCE is attributed with the mixture of an excited-state molecular orbital of the sensitizer and the orbitals of TiO2 . Between pyridine and carboxylic acid anchor dyes, opposite trends are observed in the linker-length dependence of the IPCE. The red-absorbing PcS23 is applied for co-sensitization with a carboxyl-anchor organic dye D131 that has a complementary spectral response. The site-selective adsorption of PcS23 and D131 on the TiO2 surface results in a panchromatic photocurrent response for the whole visible-light region of sun light. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
3. Synthesis of pyridine and isoquinoline labelled with 14C on the nitrogen heterocycle
International Nuclear Information System (INIS)
Robveille, Jacques
1985-01-01
This research thesis addresses the synthesis of derivatives of pyridine and isoquinoline labelled with carbon 14 ( 14 C) in the nitrogenated heterocycle as these compounds are of biological and pharmacological interest. The author aimed at developing rather general synthesis schemes which could be easily applied to the synthesis of radioactive compounds, and could produce, through a given synthesis way, the largest as possible family of differently substituted compounds. Different sources for labelled pyridine and isoquinoline have been used: dioxo-1,5 or their corresponding dioxins, substituted pentadienoic acids, derivatives of acrylic acid, and derivatives of cinnamic acid. Thus, three different synthesis processes have been developed to obtain 14 C labelled pyridine, and one of them is applied to the preparation of 14 C labelled isoquinoline. These synthesis processes can have a very general application, and allow different 14 C labelling positions to be envisaged. The possibility to obtain the same compounds but labelled with tritium can also be envisaged to obtain much higher specific activities [fr
4. Dihydropyridine-fused and pyridine-fused coumarins: Reduction on a glassy carbon electrode in dimethylformamide
International Nuclear Information System (INIS)
Nuñez-Vergara, Luis J.; Pardo-Jiménez, V.; Barrientos, C.; Olea-Azar, C.A.; Navarrete-Encina, P.A.; Squella, J.A.
2012-01-01
In this study, two series of dihydropyridine-fused and pyridine-fused coumarins were synthesised and electrochemically characterised in aprotic medium. In both series, the most easily reducible groups were the endocyclic carbonyl groups. The electrochemical mechanism for both types of compounds is strongly dependent on the experimental time-scale. Cyclic voltammetric (CV) reduction on a glassy carbon electrode (GCE) of the endocyclic carbonyl group of dihydropyridine-fused coumarins involves an ECEC mechanism with two electron transfer steps that are coupled with chemical reactions to produce the corresponding hemiacetal derivative. In the case of pyridine-fused coumarins, CV reduction of the endocyclic carbonyl group involves an EEC mechanism. ESR studies revealed the presence of a stabilised intermediate only for the pyridine-fused derivatives. Our theoretical study showed a spin density map of radical species delocalised mainly within the coumarin ring, indicating the reduction of the endocyclic carbonyl group. In the case of the dihydropyridine-fused derivatives, the mildly acid hydrogen of the dihydropyridine ring destabilises the radical via a father–son type reaction.
5. Molecular dynamics simulations of ter-pyridine and bis-triazinyl-pyridine complexes with lanthanide cations; Etude de dynamique moleculaire de complexes de la bis-triazinyl-pyridine (BTP) et de la terpyridine avec des lanthanides(3)
Energy Technology Data Exchange (ETDEWEB)
Guilbaud, Ph. [CEA Valrho, (DCC/DRRV/SEMP), 30 - Marcoule (France)
2000-07-01
The search for ligands which specifically separate actinides(III) from lanthanides(III) by liquid-liquid extraction has prompted considerable research in the Process Design and Modeling Department ('Service d'Etude et de Modelisation des Procedes'- SEMP). Ligands with soft donor atoms AS) that are able to perform this separation have already been investigated and research is currently under way to improve their performance for high acidic feeds. Theoretical chemistry research is conducted in the Theoretical and Structural Chemistry Laboratory ('Laboratoire de Chimie Theorique et Structurale') to improve our understanding of the complexation and extraction of these cations with such ligands. Theoretical studies were first carried out for the ter-pyridine (TPY) and bis-triazinyl-pyridine (BTP) ligands that display fairly good ability to separate and extract actinide(III) from lanthanide(III) ions. Molecular dynamics simulations were performed on ter-pyridine and bis-triazinyl-pyridine complexes with three lanthanide cations (La{sup 3+}, Eu{sup 3+} and Lu{sup 3+}) for vacuum and for water solutions. These calculations were carried out without counter-ions, with three nitrate (NO{sub 3}{sup -}) ions, and, in the case of ter-pyridine, with three {alpha}-bromo-caprate anions that are likely to be used experimentally as synergistic agents for the separation and extraction of An(III) from Ln(III). Molecular dynamics simulations were first performed for vacuum to evaluate the distances between nitrogen and lanthanide atoms (Ln{sup 3+},N) and intrinsic interaction energies to poly-nitrogenous ligands with or without NO{sub 3} ions, and for both ligands. The (Ln{sup 3+},N) distances decrease and the cation/ligand interaction energies increase along the La{sup 3+}, Eu{sup 3+}, Lu{sup 3+} series, with decreasing Ln(III) ion radii. The introduction of nitrate counter-ions makes the (Ln{sup 3+},N) distances slightly higher, and the TPY/Ln{sup 3+} and BTP
6. Physico-chemical properties of plasma-polymerized tetravinylsilane
Czech Academy of Sciences Publication Activity Database
Čech, V.; Studynka, J.; Conte, N.; Peřina, Vratislav
2007-01-01
Roč. 201, 9-11 (2007), s. 5512-5517 ISSN 0257-8972 Institutional research plan: CEZ:AV0Z10480505 Keywords : nano -indentation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.678, year: 2007
7. Chemistry of plasma-polymerized vinyltriethoxysilane controlled by deposition conditions
Czech Academy of Sciences Publication Activity Database
Čech, V.; Zemek, Josef; Peřina, Vratislav
2008-01-01
Roč. 5, č. 8 (2008), s. 745-752 ISSN 1612-8850 Grant - others:GAČR(CZ) GA104/06/0437 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z10480505 Keywords : ESCA/XPS * FTIR * plasma-enhanced chemical vapor deposition (PECVD) * Rutherford back-scattering (RBS) * thin films Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.921, year: 2008
8. A plasma polymerization technique to overcome cerebrospinal fluid shunt infections
Czech Academy of Sciences Publication Activity Database
Çökeliler, D.; Caner, H.; Zemek, Josef; Choukourov, A.; Biederman, H.; Mutlu, M.
2007-01-01
Roč. 2, č. 1 (2007), s. 39-47 ISSN 1748-6041 Grant - others:TUBITAK(TR) MISAG-COST 527 Institutional research plan: CEZ:AV0Z10100521 Keywords : shunt infections * cerebrospinal * PP HEMA * biomaterials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.787, year: 2007
9. Characterization of poly(methylphenylsilane) prepared by plasma polymerization
Czech Academy of Sciences Publication Activity Database
Čech, V.; Horváth, P.; Jančář, J.; Schauer, F.; Nešpůrek, Stanislav
1999-01-01
Roč. 148, - (1999), s. 321-332 ISSN 1022-1360. [International Conference on Polymer Characterization Polychar-7. Denton, 05.01.1999-11.01.1999] R&D Projects: GA ČR GV106/98/K013; GA ČR GA101/98/0855 Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.539, year: 1999
10. The optical properties of plasma polymerized polyaniline thin films
Energy Technology Data Exchange (ETDEWEB)
Goktas, Hilal, E-mail: [email protected] [Canakkale Onsekiz Mart University, Physics Department, 17020 Canakkale (Turkey); Demircioglu, Zahide; Sel, Kivanc [Canakkale Onsekiz Mart University, Physics Department, 17020 Canakkale (Turkey); Gunes, Taylan [Yalova University, Energy Systems Engineering Department, 77100 Yalova (Turkey); Kaya, Ismet [Canakkale Onsekiz Mart University, Chemistry Department, 17020 Canakkale (Turkey)
2013-12-02
We report herein the characterizations of polyaniline thin films synthesized using double discharge plasma system. Quartz glass substrates were coated at a pressure of 80 Pa, 19.0 kV pulsed and 1.5 kV dc potential. The substrates were located at different regions in the reactor to evaluate the influence of the position on the morphological and molecular structure of the obtained thin films. The molecular structure of the thin films was investigated by Fourier transform infrared (FTIR) and UV–visible photospectrometers (UV–vis), and the morphological studies were carried out by scanning electron microscope. The FTIR and UV–vis data revealed that the molecular structures of the synthesized thin films were in the form of leuocoemeraldine and exhibited similar structures with the films produced via chemical or electrochemical methods. The optical energy band gap values of the as-grown samples ranged from 2.5 to 3.1 eV, which indicated that these materials have potential applications in semiconductor devices. The refractive index in the transparent region (from 650 to 1000 nm) steadily decreased from 1.9 to 1.4 and the extinction coefficient was found to be on order of 10{sup −4}. The synthesized thin films showed various degrees of granular morphologies depending on the location of the substrate in the reactor. - Highlights: • Polyaniline thin films were synthesized for the first time via double discharge plasma system. • The films have similar structure to that of the chemically synthesized films. • The morphology of the films could be tuned by this technique. • These materials would have potential applications at semiconductor devices.
11. Characterization and properties of plasma polymerized 2-vinylpyridine
International Nuclear Information System (INIS)
Bieg, K.W.; Ottesen, D.K.; Brower, K.L.
1979-11-01
The chemical structure, aging, thermal, and adhesive behavior of plasma-deposited 2-vinylpyridine has been investigated. The molecular structure of the plasma polymer is significantly different from the conventional, linear polymer and is strongly dependent on plasma reactor variables. Additional cyano, methyl, and olefinic groups were identified in the plasma polymer, and aromaticity retention was reduced at the more severe (low pressure, high rf power) reactor conditions studied. Post-deposition oxidation occurred, which followed approximately first order kinetics initially (ΔE approx. 11.6 Kcal/mole, with approx. 25% conversion of aromatic rings to an aromatic ketone in 4.5 months at 23 0 C). Oxidation was significantly reduced in vacuum, inert gas, and hydrogen atmospheres. Thermal weight loss began at relatively low temperatures and appeared to accompany an exothermic, irreversible cross-linking reaction which began at about 100 0 C. Principle low temperature decomposition products were low molecular weight gases (primarily, CO 2 ) and 2-methylpyridine. A quantitative tensile-pull adhesion test was developed. Using this technique, the plasma polymer-aluminum cohesive bond strength was found to be 480 psi and was degraded at high humidity levels
12. Modeling the chemistry of plasma polymerization using mass spectrometry.
Science.gov (United States)
Ihrig, D F; Stockhaus, J; Scheide, F; Winkelhake, Oliver; Streuber, Oliver
2003-04-01
The goal of the project is a solvent free painting shop. The environmental technologies laboratory is developing processes of plasma etching and polymerization. Polymerized thin films are first-order corrosion protection and primer for painting. Using pure acetylene we get very nice thin films which were not bonded very well. By using air as bulk gas it is possible to polymerize, in an acetylene plasma, well bonded thin films which are stable first-order corrosion protections and good primers. UV/Vis spectroscopy shows nitrogen oxide radicals in the emission spectra of pure nitrogen and air. But nitrogen oxide is fully suppressed in the presence of acetylene. IR spectroscopy shows only C=O, CH(2) and CH(3) groups but no nitrogen species. With the aid of UV/Vis spectra and the chemistry of ozone formation it is possible to define reactive traps and steps, molecule depletion and processes of proton scavenging and proton loss. Using a numerical model it is possible to evaluate these processes and to calculate theoretical mass spectra. Adjustment of theoretical mass spectra to real measurements leads to specific channels of polymerization which are driven by radicals especially the acetyl radical. The estimated theoretical mass spectra show the specific channels of these chemical processes. It is possible to quantify these channels. This quantification represents the mass flow through this chemical system. With respect to these chemical processes it is possible to have an idea of pollutant production processes.
13. The plasma-polymerized films of dichloro(methyl)phenylsilane
Czech Academy of Sciences Publication Activity Database
Čech, V.; Horvath, P.; Zemek, J.; Trchová, M.; Matějková, Jiřina
2000-01-01
Roč. 50, Supp. S3 (2000), s. 356-364 ISSN 0011-4626. [Plasma Physics and Technology /10./. Praha, 06.07.2000-09.07.2000] R&D Projects: GA ČR GV106/98/K013; GA ČR GA104/00/0708 Institutional research plan: CEZ:AV0Z2065902 Subject RIV: JR - Other Machinery Impact factor: 0.298, year: 2000
14. Tailoring Silica Surface Properties by Plasma Polymerization for Elastomer Applications
NARCIS (Netherlands)
Tiwari, M.; Dierkes, Wilma K.; Datta, Rabin; Talma, Auke; Noordermeer, Jacobus W.M.; van Ooij, W.J.
2009-01-01
The surface properties of reinforcing fillers are a crucial factor for dispersion and filler–polymer interaction in rubber compounds, as they strongly influence the final vulcanized properties of the rubber article. Silica is gaining more and more importance as reinforcing filler for rubbers, as it
15. Tailoring Silica Surface Properties by Plasma Polymerization for Elastomer Applications
NARCIS (Netherlands)
Tiwari, M.; Dierkes, W.K.; Datta, R.N.; Talma, A.G.; Noordermeer, J.W.M.; van Ooij, W.J.
2011-01-01
The surface properties of reinforcing fillers are a crucial factor for dispersion and filler–polymer interaction in rubber compounds, as they strongly influence the final vulcanized properties of the rubber article. Silica is gaining more and more importance as reinforcing filler for rubbers, as it
16. Rhodium(III)-Catalyzed ortho-Alkylation of Phenoxy Substrates with Diazo Compounds via C-H Activation: A Case of Decarboxylative Pyrimidine/Pyridine Migratory Cyclization Rather than Removal of Pyrimidine/Pyridine Directing Group.
Science.gov (United States)
Ravi, Manjula; Allu, Srinivasarao; Swamy, K C Kumara
2017-03-03
An efficient Rh(III)-catalyzed ortho-alkylation of phenoxy substrates with diazo compounds has been achieved for the first time using pyrimidine or pyridine as the directing group. Furthermore, bis-alkylation has also been achieved using para-substituted phenoxypyrimidine and 3 mol equiv of the diazo ester. The ortho-alkylated derivatives of phenoxy products possessing the ester functionality undergo decarboxylative pyrimidine/pyridine migratory cyclization (rather than deprotection of pyrimidine/pyridine group) using 20% NaOEt in EtOH affording a novel class of 3-(pyrimidin-2(1H)-ylidene)benzofuran-2(3H)-ones and 6-methyl-3-(pyridin-2(1H)-ylidene)benzofuran-2(3H)-one. The ortho-alkylated phenoxypyridine possessing ester functionality also undergoes decarboxylative pyridine migratory cyclization using MeOTf/NaOMe in toluene providing 6-methyl-3-(1-methylpyridin-2(1H)-ylidene)benzofuran-2(3H)-one.
17. 3-Ethyl-5-(4-methoxyphenoxy)-2-(pyridin-4-yl)-3H-imidazo[4,5-b]pyridine
Science.gov (United States)
Ranjith, S.; SubbiahPandi, A.; Suresh, A. D.; Pitchumani, K.
2011-01-01
In the title compound, C20H18N4O2, the imidazopyridine fused ring system is almost perpendicular to the benzene ring [dihedral angle = 87.6 (5)°]. The pyridine ring makes a dihedral angle of 35.5 (5)° with the mean plane of the imidazopyridine fragment. The crystal structure is stabilized by an aromatic π–π stacking interaction between the phenyl rings of neighbouring molecules [centroid–centroid distance = 3.772 (2) Å, interplanar distance = 3.546 (2) Å and slippage = 1.286 (2) Å]. PMID:21837144
18. Synthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexes
KAUST Repository
Lenton, Taylor N.
2012-11-12
A precursor to a new tridentate LX 2 type ligand, bis(thiophenol)pyridine ((SNS)H 2 = (2-C 6H 4SH) 2-2,6-C 5H 3N), was prepared. Bis(thiophenolate)pyridine complexes of Ti, Zr, and Ta having dialkylamido coligands were synthesized and structurally characterized. The zirconium complex (SNS)Zr(NMe 2) 2 (4) displays C 2 symmetry in the solid state, unlike a related bis(phenolate)pyridine compound, C s-symmetric (ONO)Ti(NMe 2) 2. This change is likely the result of strain about the sulfur atom in the six-membered chelate with longer metal-sulfur and carbon-sulfur bonds. Solid-state structures of tantalum complexes (SNS)Ta(NMe 2) 3 (5) and (SNS)TaCl(NEt 2) 2 (6) also display pronounced C 2 twisting of the SNS ligand. 1D and 2D NMR experiments show that 5 is fluxional, with rotation about the Ta-N(amide) bonds occurring on the NMR time scale that interchange the equatorial amide methyl groups (ΔG ‡ 393 = 25.0(3) kcal/mol). The fluxional behavior of 6 in solution was also studied by variable-temperature 1H NMR. Observation of separate signals for the diastereotopic protons of the methylene unit of the diethylamide indicates that the complex remains locked on the NMR time scale in one diastereomeric conformation at temperatures below -50 °C, fast rotation about the equatorial amide Ta-N bonds occurs at higher temperature (ΔG ‡ 393 = 13.4(3) kcal/mol), and exchange of diastereomeric methylene protons occurs via inversion at Ta that interconverts antipodes (ΔG ‡ 393 ≈ 14(1) kcal/mol). © 2012 American Chemical Society.
19. Reaction of pyridine-N-oxides with halogens; Vzaimodejstvie piridin-N-oksidov s galogenami
Energy Technology Data Exchange (ETDEWEB)
Kanibolotskij, A L; Mikhzajlov, V A; Savelova, V A [AN Ukrainskoj SSR, Donetsk (Ukraine). Inst. Fiziko-Organicheskoj Khimii i Uglekhimii
1994-12-31
By the methods of conductometry, NMR and IR spectroscopy it has been ascertained that interaction of pyridine-N-oxides with bromine, iodine and interhalides (ICl and IBr) gives rise to the formation of crystal complexes of 1:1 composition. The complexes mentioned are of presumably ionic structure: [RC{sub 5}H{sub 4}N-O...X...O-NC{sub 5}H{sub 4}R]{sup +}[Y-X-Y]{sup -},where X,Y = Cl,Br,I.
20. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex
International Nuclear Information System (INIS)
Arya, S. P.; Mahajan, M.
1998-01-01
A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 μg ml -1 . Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C [it
1. Determination of low concentrations of pyridine in piperidine by gas chromatography and infrared spectroscopy
International Nuclear Information System (INIS)
Perez Garcia, M. M.; Parellada Bellod, R.
1979-01-01
This paper describes the determination of low amounts of piperidine in pyridine in the concentration range of 0-5%. After an exhausting review of the bibliography on the column selection, the chromatographic separation and determination are made on the following column: 27% Pennwalt- 223; 4% KOH on Gas-Chrom R; 80-100 mesh with flame ionization detector. The retention indexes of both compounds and tho Rohrschneider constants of the phase used are calculated. The minimum detection limit achieved for piperidine is 0,25%. (Author) 25 refs
2. 5-Bromo-N3-[(E-(6-bromopyridin-2-ylmethylidene]pyridine-3,4-diamine
Directory of Open Access Journals (Sweden)
Mingjian Cai
2011-12-01
Full Text Available The title compound, C11H8Br2N4, is a Schiff base obtained from 6-bromopicolinaldehyde and 5-bromopyridine-3,4-diamine. The molecule has an E configuration about the C=N bond and the dihedral angle between the two pyridine rings is 14.02 (1°. The observed conformation is stabilised by an intramolecular N—H...N hydrogen bond. In the crystal, molecules are stacked along the b axis and are linked through N—H...N hydrogen bonds into chains along the c axis.
3. (E-3-[5-(Diphenylaminothiophen-2-yl]-1-(pyridin-3-ylprop-2-en-1-one
Directory of Open Access Journals (Sweden)
Rui Li
2013-09-01
Full Text Available In the title compound, C24H18N2OS, the pyridine and the two phenyl rings are oriented at dihedral angles of 10.1 (5, 71.7 (6 and 68.7 (5°, respectively, to the central thiophene ring. In the crystal, pairs of weak C—H...O hydrogen bonds link inversion-related molecules, forming dimers. The dimers are linked by further weak C—H...O hydrogen bonds, forming chains running along the a-axis direction.
4. Synthesis, spectroscopic and thermochemical studies of some novel carbazole-pyridine co-polymers (abstract)
International Nuclear Information System (INIS)
Saeed, A.; Irfan, M.
2011-01-01
Two series of a novel class of carbazole-4-phenylpyridine co-polymers has been synthesized by a modified Chichibabin reaction. The synthesis was carried out by a simple and cheaper method compared to the lengthy methods usually adopted for the preparation of carbazole-pyridine copolymers which involve costly catalysts. All the polymers were characterized by IR, /sup 1/H and /sup 13/C NMR, UV-vis spectroscopy, fluorimetry, TGA and DSC. The weight average molecular masses (M/sub w/) of the polymers were estimated by Laser Light Scattering (LLS) technique. (author)
5. Ternary systems, consist of erbium nitrates, water and nitrates of pyridines, quinolines
International Nuclear Information System (INIS)
Starikova, L.I.; Zhuravlev, E.F.; Khalfina, L.R.
1979-01-01
At 25 and 50 deg C investigated is solubility of solid phases in ternary water salt systems: erbium nitrate-pyridine nitrate-water; erbium nitrate-quinoline nitrate-water. Formation of congruently soluble compounds of the Er(NO 3 ) 3 x2C 5 H 5 NxHNO 3 , Er(NO 3 ) 3 x2C 9 H 7 NxHNO 3 x4H 2 O composition is established. X-ray phase and thermogravimetric analyses have been carried out
6. Oxidation reactivity channels for 2-(pyridin-2-yl)-N,N-diphenylacetamides
Energy Technology Data Exchange (ETDEWEB)
Pailloux, Sylvie; Binyamin, Iris; Deck, Lorraine M.; Rapko, Brian M.; Hay, Benjamin P.; Duesler, Eileen N.; Paine, Robert T.
2007-11-01
Synthetic routes to 2-(pyridin-2-yl)-N,N-diphenylacetamide and 2-(6-methylpyridin-2-yl)-N,N-diphenylacetamide are described along with results from the chemical oxidation of these compounds with peracetic acid, m-chloroperbenzoic acid, and OXONE. In each case, oxidations generate four products in varying amounts depending on the oxidant and reaction conditions. Each product has been characterized by spectroscopic methods and the molecular structures of several of the new compounds have been confirmed by X-ray crystallography.
7. Oxidation Reactivity Channels for 2-(Pyridin-2-yl)-N,N-diphenyl-acetamides
Energy Technology Data Exchange (ETDEWEB)
Pailloux, Sylvie [University of New Mexico, Albuquerque; Binyamin, Iris [University of New Mexico, Albuquerque; Kim, Sung-jun [University of New Mexico, Albuquerque; Deck, Lorraine M. [University of New Mexico, Albuquerque; Rapko, Brian M. [Pacific Northwest National Laboratory (PNNL); Hay, Benjamin [ORNL; Duesler, Eileen N. [University of New Mexico, Albuquerque; Paine, Robert T. [University of New Mexico, Albuquerque
2007-11-01
Synthetic routes to 2-(pyridin-2-yl)-N,N-diphenylacetamide and 2-(6-methylpyridin-2-yl)-N,N-diphenyl-acetamide are described along with results from the chemical oxidation of these compounds with peracetic acid, m-chloroperbenzoic acid, and OXONE. In each case, oxidations generate four products in varying amounts depending on the oxidant and reaction conditions. Each product has been characterized by spectroscopic methods and the molecular structures of several of the new compounds have been confirmed by X-ray crystallography.
8. 2,3-Diamino?pyridinium 6-carb?oxy?pyridine-2-carboxyl?ate
OpenAIRE
Foroughian, Mahsa; Foroumadi, Alireza; Notash, Behrouz; Bruno, Giuseppe; Amiri Rudbari, Hadi; Aghabozorg, Hossein
2011-01-01
The asymmetric unit of the title proton-transfer compound, C5H8N3+·C7H4NO4−, consists of one mono-deprotonated pyridine-2,6-dicarboxylic acid as anion and one protonated 2,3-diaminopyridine as cation. The crystal packing shows extensive O—H...O, N—H...O and N—H...N hydrogen bonds. Thre are also several π–π interactions between the anions and also between the cations [centriod–centroid distances = 3.6634&...
Directory of Open Access Journals (Sweden)
Sarvendra Kumar
2012-02-01
Full Text Available In the title compound, [Co(C4H9(C14H11N2O22(C5H5N], the CoIII atom is coordinated by a butyl group, a nitrogen-bonded pyridine and two N,N′-bidentate diphenylglyoximate ligands in a distorted octahedral geometry. The crystal structure features two short O—H...O bridges between the two chelating anions, with O...O distances less than 2.5 Å.
10. Synthesis of 2,4,6-Trisubstituted Pyridines by Oxidative Eosin Y Photoredox Catalysis.
Science.gov (United States)
Rohokale, Rajendra S; Koenig, Burkhard; Dhavale, Dilip D
2016-08-19
Eosin Y, an organic dye, was activated as a photoredox catalyst in the presence of molecular oxygen using visible light and, when it was used in the reaction of aryl ketones and benzyl amines, afforded good yields (52-87%) of 2,4,6-triarylpyridines (21 examples) at ambient temperature. The aryl groups at the 2- and 6-positions are derived from ketones, while benzyl amine plays the dual role of providing an aryl functionality at the 4-position of pyridine as well as being a nitrogen donor.
11. Synthesis of modified pyridine and bipyridine substituted coumarins as potent antimicrobial agents
Directory of Open Access Journals (Sweden)
2015-01-01
Full Text Available In search for new antimicrobial agents a series of new modified pyridine and bipyridine substituted coumarins 5a-y was designed and synthesized by adopting molecular hybridization strategy. All the synthesized compounds were evaluated for their in vitro antimicrobial activity using broth dilution method against selected bacterial (Gram-positive and Gram-negative and fungal strains. Compounds 5a, 5f, 5g, 5n, 5r, 5t, 5w, 5x and 5y demonstrated promising antibacterial activity while other derivatives showed comparable activity to standard drugs used as reference.
12. Complexation of thorium with pyridine monocarboxylates: A thermodynamic study by experiment and theory
International Nuclear Information System (INIS)
Rama Mohana Rao, D.; Rawat, Neetika; Manna, D.; Sawant, R.M.; Ghanty, T.K.; Tomar, B.S.
2013-01-01
Highlights: ► The thermodynamic parameters have been determined for the first time. ► The Th-picolinate complexation was exothermic in nature. ► The complexation of Th(IV) with the other two isomers was endothermic process. ► Isonicotinate forms stronger complexes than nicotinate with Th(IV). ► The theoretically calculated values are in line with the experimental results. -- Abstract: Complexation of thorium with pyridine monocarboxylates namely picolinic acid (pyridine-2-carboxylic acid), nicotinic acid (pyridine-3-carboxylic acid) and isonicotinic acid (pyridine-4-carboxylic acid) has been studied by potentiometry and calorimetry to determine the thermodynamic parameters (log K, ΔG, ΔH and ΔS) of complexation. All the studies were carried out at 1.0 M ionic strength adjusted by NaClO 4 and at a temperature of 298 K. The detailed analysis of potentiometric data by Hyperquad confirmed the formation of four complexes, ML i (i = 1–4) in case of picolinate but only one complex (ML) in case of nicotinate and isonicotinate. The stepwise formation constant for ML complex (log K ML ) of thorium-picolinate is higher than those of thorium-nicotinate and thorium-isonicotinate complexes. Further the changes in enthalpy during formation of thorium-picolinate complexes are negative whereas the same for the complexes of thorium with the other two isomers was positive. This difference in the complexation process is attributed to chelate formation in case of thorium-picolinate complexes in which the thorium ion is bound to the picolinate through both the nitrogen in the pyridyl ring and one of the carboxylate oxygen atoms. The complexation process of thorium-nicotinate and thorium-isonicotinate are found to be endothermic in nature and are entropy driven confirming the similar binding nature as in simple carboxylate complexes of thorium. The complexation energies, bond lengths and charges on each atom in the complexes of various possible geometries were calculated
13. Systems of pyridine, piperidine, piperazine, morpholine hydrochlorides-terbium (dysprosium) chloride-water
International Nuclear Information System (INIS)
Gajfutdinova, R.K.; Sharafutdinova, A.A.; Murinov, Yu.I.
1988-01-01
The isothermal cross section method at 25 and 50 deg C is applied to study pyridine hydrochloride-terbium chloride-water (1) piperidine hydrochloride-dysprosium chloride-water (2), piperazine dihydrochloride-dysprosium chloride-water (3) and morpholine hydrochloride-terbium chloride (4) systems. Solubility isotherma prove the formation of incongruently soluble compound of the TbCl 3 x6C 5 H 5 NxHCl composition systems (1). The individuality of the new solid phase is proved by the chemical and DTA methods. Systems (2-4) are of a simple eutonic type
14. Oppositines A and B, Sesquiterpene Pyridine Alkaloids from a Sri Lankan Pleurostylia opposita
Science.gov (United States)
Whitson, Emily L.; Mala, S.M.V. Damayanthi; Veltri, Charles. A.; Bugni, Tim S.; de Silva, E. Dilip; Ireland, Chris M.
2008-01-01
Two new sesquiterpene pyridine alkaloids, oppositines A (1) and B (2), have been isolated from the plant, Pleurostylia opposita (Celastraceae), collected in Sri Lanka. The compounds were isolated and purified by solvent/solvent partitioning, column chromatography and HPLC. Their structures were assigned on the basis of extensive 1D and 2D NMR studies as well as analysis by HRESIMS. Oppositines A (1) and B (2) showed moderate cytotoxicity against HCT116 cell lines with EC50 values of 27 ± 2 and 26 ± 3 μM, respectively. PMID:17190474
15. Bis(2-hydroxy-N′-isopropylidenebenzohydrazidato-κ2N′,Obis(pyridine-κNcobalt(II
Directory of Open Access Journals (Sweden)
Xiaojuan Zhao
2009-04-01
Full Text Available In the title complex, [Co(C10H11N2O22(C5H5N2], the CoII atom lies on a centre of symmetry and adopts a distorted cis-CoO2N4 octahedral geometry. The two acetone salicyloylhydrazone ligands are deprotonated and act as N,O-bidentate monoanionic ligands, forming the equatorial plane, while the axial positions are occupied by two N atoms of two pyridine molecules. The complex presents O—H...N and C—H...N intramolecular hydrogen bonds. Intermolecular C—H...N and C—H...O interactions are also present in the crystal.
16. fac-Tris(pyridine-2-carboxylato-κ2N,Ocobalt(III
Directory of Open Access Journals (Sweden)
Irina A. Golenia
2011-11-01
Full Text Available In the title compound, [Co(C6H4NO23], the CoIII ion lies on a threefold rotation axis and is in a distorted octahedral environment defined by three N and three O donor atoms from three fac-disposed pyridine-2-carboxylate ligands. The ligands are coordinated in a chelate fashion, forming three five-membered rings. In the crystal, translationally related complex molecules are organized into columns along [001] via C—H...O hydrogen bonds.
17. fac-Tris(pyridine-2-carboxylato-κ2 N,O)cobalt(III)
Science.gov (United States)
Golenia, Irina A.; Boyko, Alexander N.; Kotova, Natalia V.; Haukka, Matti; Kalibabchuk, Valentina A.
2011-01-01
In the title compound, [Co(C6H4NO2)3], the CoIII ion lies on a threefold rotation axis and is in a distorted octahedral environment defined by three N and three O donor atoms from three fac-disposed pyridine-2-carboxylate ligands. The ligands are coordinated in a chelate fashion, forming three five-membered rings. In the crystal, translationally related complex molecules are organized into columns along [001] via C—H⋯O hydrogen bonds. PMID:22219826
18. Synthesis of new pyrrole–pyridine-based ligands using an in situ Suzuki coupling method
Directory of Open Access Journals (Sweden)
Matthias Böttger
2012-07-01
Full Text Available The compounds 6-(pyrrol-2-yl-2,2‘-bipyridine, 2-(pyrrol-2-yl-1,10-phenanthroline and 2-(2-(N-methylbenz[d,e]imidazole-6-(pyrrol-2-yl-pyridine were synthesized by using an in situ generated boronic acid for the Suzuki coupling. Crystals of the products could be grown and exhibited interesting structures by X-ray analysis, one of them showing a chain-like network with the adjacent molecules linked to each other via intermolecular N–H…N hydrogen bonds.
19. Computational, electrochemical, and spectroscopic studies of two mononuclear cobaloximes: the influence of an axial pyridine and solvent on the redox behaviour and evidence for pyridine coordination to cobalt(I) and cobalt(II) metal centres†
Science.gov (United States)
Lawrence, Mark A. W.; Celestine, Michael J.; Artis, Edward T.; Joseph, Lorne S.; Esquivel, Deisy L.; Ledbetter, Abram J.; Cropek, Donald M.; Jarrett, William L.; Bayse, Craig A.; Brewer, Matthew I.; Holder, Alvin A.
2018-01-01
[Co(dmgBF2)2(H2O)2] 1 (where dmgBF2 = difluoroboryldimethylglyoximato) was used to synthesize [Co(dmgBF2)2(H2O)(py)]·0.5(CH3)2CO 2 (where py = pyridine) in acetone. The formulation of complex 2 was confirmed by elemental analysis, high resolution MS, and various spectroscopic techniques. The complex [Co(dmgBF2)2(solv)(py)] (where solv = solvent) was readily formed in situ upon the addition of pyridine to complex 1. A spectrophotometric titration involving complex 1 and pyridine proved the formation of such a species, with formation constants, log K = 5.5, 5.1, 5.0, 4.4, and 3.1 in 2-butanone, dichloromethane, acetone, 1,2-difluorobenzene/acetone (4 : 1, v/v), and acetonitrile, respectively, at 20 °C. In strongly coordinating solvents, such as acetonitrile, the lower magnitude of K along with cyclic voltammetry, NMR, and UV-visible spectroscopic measurements indicated extensive dissociation of the axial pyridine. In strongly coordinating solvents, [Co(dmgBF2)2(solv)(py)] can only be distinguished from [Co(dmgBF2)2(solv)2] upon addition of an excess of pyridine, however, in weakly coordinating solvents the distinctions were apparent without the need for excess pyridine. The coordination of pyridine to the cobalt(II) centre diminished the peak current at the Epc value of the CoI/0 redox couple, which was indicative of the relative position of the reaction equilibrium. Herein we report the first experimental and theoretical 59Co NMR spectroscopic data for the formation of Co(I) species of reduced cobaloximes in the presence and absence of py (and its derivatives) in CD3CN. From spectroelectrochemical studies, it was found that pyridine coordination to a cobalt(I) metal centre is more favourable than coordination to a cobalt(II) metal centre as evident by the larger formation constant, log K = 4.6 versus 3.1, respectively, in acetonitrile at 20 °C. The electrosynthesis of hydrogen by complexes 1 and 2 in various solvents demonstrated the dramatic effects of the axial
Science.gov (United States)
Visentin, Fabiano; Santo, Claudio; Scattolin, Thomas; Demitri, Nicola; Canovese, Luciano
2017-08-08
As an extension of a previously published work we have reacted some palladacyclopentadiene complexes stabilized by bidentate N-heterocyclic carbene-pyridine or monodentate N-heterocyclic carbene-pyridine and isocyanide ligands with the halogens I 2 and Br 2 . All the bidentate and monodentate complexes react with halogens to give at first the expected σ-coordinated butadienyl fragment. However, two of the less hindered NHC carbene-pyridine bidentate butadienyl iodo derivatives undergo a further rearrangement and novel Pd(ii) complexes characterized by a ten term coordinative ring were isolated and characterized. In the most favorable case we were able to carry out the kinetics of rearrangement and measure its reaction rate. Moreover, we have surmised a plausible mechanism on the basis of a dedicated computational approach and in one case the surprising structure characterized by the ten term coordinative ring was resolved by X-ray diffraction.
1. catena-Poly[[bromidocopper(I)]-?-?2,?1-3-(2-allyl-2H-tetra?zol-5-yl)pyridine
OpenAIRE
Wang, Wei
2008-01-01
The title compound, [CuBr(C9H9N5)] n , has been prepared by the solvothermal treatment of CuBr with 3-(2-allyl-2H-tetra?zol-5-yl)pyridine. It is a new homometallic CuI olefin coord?ination polymer in which the CuI atoms are linked by the 3-(2-allyl-2H-tetra?zol-5-yl)pyridine ligands and bonded to one terminal Br atom each. The organic ligand acts as a bidentate ligand connecting two neighboring Cu centers through the N atom of the pyridine ring and the double bond of the allyl group. A three-...
2. Carbon dioxide is tightly bound in the [Co(Pyridine)(CO{sub 2})]{sup −} anionic complex
Energy Technology Data Exchange (ETDEWEB)
Graham, Jacob D.; Buytendyk, Allyson M.; Zhang, Xinxing; Bowen, Kit H., E-mail: [email protected] [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Kim, Seong K. [Department of Chemistry, Seoul National University, Seoul 151-747 (Korea, Republic of)
2015-11-14
The [Co(Pyridine)(CO{sub 2})]{sup −} anionic complex was studied through the combination of photoelectron spectroscopy and density functional theory calculations. This complex was envisioned as a primitive model system for studying CO{sub 2} binding to negatively charged sites in metal organic frameworks. The vertical detachment energy (VDE) measured via the photoelectron spectrum is 2.7 eV. Our calculations imply a structure for [Co(Pyridine)(CO{sub 2})]{sup −} in which a central cobalt atom is bound to pyridine and CO{sub 2} moieties on either sides. This structure was validated by acceptable agreement between the calculated and measured VDE values. Based on our calculations, we found CO{sub 2} to be bound within the anionic complex by 1.4 eV.
3. Analysis of denitrifier community in a bioaugmented sequencing batch reactor for the treatment of coking wastewater containing pyridine and quinoline
Energy Technology Data Exchange (ETDEWEB)
Bai, Yaohui; Xing, Rui; Wen, Donghui; Tang, Xiaoyan [Peking Univ., Beijing (CN). Key Lab. of Water and Sediment Sciences (Ministry of Education); Sun, Qinghua [Peking Univ., Beijing (CN). Key Lab. of Water and Sediment Sciences (Ministry of Education); Chinese Center for Disease Control and Prevention, Beijing (China). Inst. of Environmental Health and Related Product Safety
2011-05-15
The denitrifier community and associated nitrate and nitrite reduction in the bioaugmented and general sequencing batch reactors (SBRs) during the treatment of coking wastewater containing pyridine and quinoline were investigated. The efficiency and stability of nitrate and nitrite reduction in SBR was considerably improved after inoculation with four pyridine- or quinoline-degrading bacterial strains (including three denitrifying strains). Terminal restriction fragment length polymorphism (T-RFLP) based on the nosZ gene revealed that the structures of the denitrifier communities in bioaugmented and non-bioaugmented reactors were distinct and varied during the course of the experiment. Bioaugmentation protected indigenous denitrifiers from disruptions caused by pyridine and quinoline. Clone library analysis showed that one of the added denitrifiers comprised approximately 6% of the denitrifier population in the bioaugmented sludge. (orig.)
4. The study of interaction of lanthanum-, cerium- and neodymium chlorides with sodium borohydride in pyridine- and tetrahydrofuran medium
International Nuclear Information System (INIS)
Mirsaidov, U.; Rotenberg, T.G.; Dymova, T.N.
1976-01-01
Bis-tetrahydrofurans of lanthanum and neodymium borohydrides and bis-pyridinates of lanthanum, cerium and neodymium borohydrides were obtained by interacting sodium borohydride with lanthanum-, cerium and neodymium chlorides in pyridine and tetrahydrofuran media. All operations involving reagent combination, sampling and phase separation are performed in inert atmosphere using argonvacuum equipment. The reaction in pyridine was virtually instantaneous and accompanied by flocculanet precipitation. The interaction of lanthanum chloride and neodymium chloride with sodium borohydride in tetrahydrofuran (THF) was a slow (23-30 hr) heterophase process. The interaction rate was affected by size reduction of the intial substances, temperature, reagent proportion and mixing rate. The reaction time was twice reduced with boiling tetrahydrofuran
5. Diphenyl (4′-(Aryldiazenylbiphenyl-4-ylamino(pyridin-3-ylmethylphosphonates as Azo Disperse Dyes for Dyeing Polyester Fabrics
Directory of Open Access Journals (Sweden)
Mohamed F. Abdel-Megeed
2013-01-01
Full Text Available Diphenyl (4′-aminobiphenyl-4-ylamino(pyridin-3-ylmethylphosphonate (1 was synthesized in 88% yield from reaction of pyridine-3-carboxaldehyde with benzidine and triphenylphosphite in the presence of titanium tetrachloride as a catalyst. Diazotization of 1 gave the corresponding diazonium salt 2 which was coupled with several hydroxyl or amino compounds to give the corresponding azo dyes 3–8 in 82–88% yields after crystallization. The dyes produced were applied to polyesters as disperse dyes and their fastness properties were elevated.
6. Crystal structure of [tris(pyridin-2-ylmethyl)amine-κ4N]copper(II) bromide
OpenAIRE
Emma C. Bridgman; Megan M. Doherty; Kaleigh A. Ellis; Elizabeth A. Homer; Taylor N. Lashbrook; Margaret E. Mraz; Gina C. Pernesky; Emma M. Vreeke; Kayode D. Oshin; Allen G. Oliver
2016-01-01
In the asymmetric unit of the title compound, [CuBr(C18H18N4)]Br, there are three crystallographically independent cations. One of the cations exhibits positional disorder of the pyridin-2-yl?methyl groups over two sets of sites with refined occupancies of 0.672?(8) and 0.328?(8). The outer-sphere bromine counter-ion is severely disordered over multiple sites. In each cation, the CuII ion is coordinated by the four N atoms of the tris?(pyridin-2-ylmeth?yl)amine ligand and one bromine and adop...
7. FT-IR Spectroscopic study on the 4-(3-Cyclohexen-1-yl)pyridine metal (II) tetracyanonickelate complex
International Nuclear Information System (INIS)
Parlak, C.
2005-01-01
New Hofmann type complex in the form of M(4-Chpy) 2 Ni(CN) 4 (where 4-Chpy=4-(3- Cyclohexen-1-yl)pyridine and M = Ni) was prepared in powder form and its infrared spectra is reported in the range of 4000-400 cm - 1. The spectral findings suggest that this compound is similar in structure to the Hofmann type complexes and its structure consists of polymeric layers | M-Ni(CN) 4 |∞ with the 4-(3-Cyclohexen-1-yl)pyridine molecule bound to the metal atom (M)
8. SYNTHESIS AND CHARACTERIZATION OF NEW THERMALLY STABLE POLYAMIDES BASED ON 2,5-PYRIDINE DICARBOXYLIC ACID AND AROMATIC DIAMINES
OpenAIRE
FAGHIHI, KHALIL
2009-01-01
Six new thermally stable polyamides 3a-f were synthesized through the polycondensation reaction of 2,5-pyridine dicarboxylic acid 1 with six different derivatives of aromatic diamines 2a-f in amedium consisting of N-methyl-2-pyrrolidone, triphenyl phosphite, calcium chloride and pyridine. The polycondensation reaction produced a series of novel polyamides containing pyridyl moieties in the main chain in high yield with inherent viscosities between 0.50-0.82 dL/g. The resulting polymers were f...
9. Molecular dynamics simulations of ter-pyridine, BTP, and their complexes with La3+, Eu3+ and Lu3+
International Nuclear Information System (INIS)
Guilbaud, P.; Dognon, J.P.
2000-01-01
This poster presents molecular dynamics simulations performed to study ter-pyridine and bis-triazinyl-pyridine with lanthanide cations for the gas phase and for water solution. Different counter-ions have been tested in order to assess their influence on complexes structures and stabilities in both phases. For stable complexes, Gibbs free energy calculations have been achieved to estimate the selectivity of these complexes towards the lanthanide cations. Finally, some tests have been done adding a polarization term in the potential energy in order to have a more precise description of interaction energies. (authors)
10. FTIR investigation of the reaction between pyridine and iodine in a polyethylene host. Formation of N-iodopyridinium polyiodide
DEFF Research Database (Denmark)
Karlsen, Eva; Spanget-Larsen, Jens
2009-01-01
The reaction between pyridine and I2 in a low-density polyethylene (LDPE) host is investigated by FTIR vibrational spectroscopy in the mid- and far-IR regions. The investigation is supported by linear dichroism measurements on stretched LDPE samples, and by the results of quantum chemical density...... functional theoretical (DFT) calculations. Unlike the situation in liquid alkane solutions, pyridine and I2 dissolved in LDPE react to form N-iodopyridinium polyiodide. The ionic reaction is particularly efficient in stretched LDPE, suggesting that the reaction cavities in the stretched polymer catalyze...
11. Synthesis of polysubstituted 4,5,6,7-tetrahydrofuro[2,3-c]pyridines by a novel multicomponent reaction.
Science.gov (United States)
Fayol, Aude; Zhu, Jieping
2004-01-08
[reaction: see text] A novel three-component synthesis of tetrahydrofuro[2,3-c]pyridines from readily accessible starting materials is described. Simply heating a toluene solution of an aminopentynoate, an aldehyde, and an alpha-isocyanoacetamide in the presence of ammonium chloride provided the 4,5,6,7-tetrahydrofuro[2,3-c]pyridines in good to excellent yield. The fused ring system is produced in this one-pot process by the concomitant formation of five chemical bonds.
12. Pyridine substituted spirofluorene derivative as an electron transport material for high efficiency in blue organic light-emitting diodes
Energy Technology Data Exchange (ETDEWEB)
Jeon, Soon Ok; Yook, Kyoung Soo; Lee, Jun Yeob, E-mail: [email protected]
2010-11-01
The quantum efficiency of blue fluorescent organic light-emitting diodes was enhanced by 20% using a pyridine substituted spirofluorene-benzofluorene derivative as an electron transport material. 2',7'-Di(pyridin-3-yl)spiro[benzofluorene-7,9'-fluorene] (SPBP) was synthesized and it was used as the electron transport material to block the hole leakage from the emitting layer. The improvement of the quantum efficiency and power efficiency of the blue fluorescent organic light-emitting diodes using the SPBP was investigated.
13. Coordination chemistry of gadolinium complexes having pyridine carboxylate units in relation with the medical imagery
International Nuclear Information System (INIS)
Gateau, C.; Chatterton, N.; Nonat, A.; Mazzanti, M.; Pecaut, J.; Borel, A.; Merbach, A.; Heim, L.
2005-01-01
In order to study the influence of the coordination sphere on the properties which govern the relaxivity, ligands containing pyridine carboxylates units have been particularly studied. It has been shown that the tripodal ligand tpaa forms with gadolinium (III) a neutral complex having a relaxivity (r1p=13.3 mM -1 at 298 K and 60 MHz) which is three times superior to the contrast agents currently used in NMR Imaging. To explain this remarkably relaxivity, two new ligands analogous to the tpaa: the tpatcn and the bpeda containing pyridine carboxylate units bound to one or several aliphatic nitrogen have been studied in modulating the number of coordination sites and the symmetry degree. The study of the relaxivity of the corresponding gadolinium (III) complexes gives precious data on the understanding of the results in the case of the complex [Gd(tpaa)]. The synthesis and the properties of these gadolinium (III) complexes will be presented during this conference. (O.M.)
14. Biotransformation of fluorophenyl pyridine carboxylic acids by the model fungus Cunninghamella elegans.
Science.gov (United States)
Palmer-Brown, William; Dunne, Brian; Ortin, Yannick; Fox, Mark A; Sandford, Graham; Murphy, Cormac D
2017-09-01
1. Fluorine plays a key role in the design of new drugs and recent FDA approvals included two fluorinated drugs, tedizolid phosphate and vorapaxar, both of which contain the fluorophenyl pyridyl moiety. 2. To investigate the likely phase-I (oxidative) metabolic fate of this group, various fluorinated phenyl pyridine carboxylic acids were incubated with the fungus Cunninghamella elegans, which is an established model of mammalian drug metabolism. 3. 19 F NMR spectroscopy established the degree of biotransformation, which varied depending on the position of fluorine substitution, and gas chromatography-mass spectrometry (GC-MS) identified alcohols and hydroxylated carboxylic acids as metabolites. The hydroxylated metabolites were further structurally characterised by nuclear magnetic resonance spectroscopy (NMR), which demonstrated that hydroxylation occurred on the 4' position; fluorine in that position blocked the hydroxylation. 4. The fluorophenyl pyridine carboxylic acids were not biotransformed by rat liver microsomes and this was a consequence of inhibitory action, and thus, the fungal model was crucial in obtaining metabolites to establish the mechanism of catabolism.
15. Changes in pyridine metabolism profile during growth of trigonelline-forming Lotus japonicus cell cultures.
Science.gov (United States)
Yin, Yuling; Matsui, Ayu; Sakuta, Masaaki; Ashihara, Hiroshi
2008-12-01
Changes in the profile of pyridine metabolism during growth of cells were investigated using trigonelline-forming suspension-cultured cells of Lotus japonicus. Activity of the de novo and salvage pathways of NAD biosynthesis was estimated from the in situ metabolism of [(3)H] quinolinic acid and [(14)C] nicotinamide. Maximum activity of the de novo pathway for NAD synthesis was found in the exponential growth phase, whereas activity of the salvage pathway was increased in the lag phase of cell growth. Expression profiles of some genes related to pyridine metabolism were examined using the expression sequence tags obtained from the L. japonicus database. Transcript levels of NaPRT and NIC, encoding salvage enzymes, were enhanced in the lag phase of cell growth, whereas the maximum expression of NADS was found in the exponential growth phase. Correspondingly, the activities of the salvage enzymes, nicotinate phosphoribosyltransferase (EC 2.4.2.11) and nicotinamidase (EC 3.5.1.19), increased one day after transfer of the stationary phase cells to the fresh medium. The greatest in situ trigonelline synthesis, both from [(3)H] quinolinic acid and [(14)C] nicotinamide, was found in the stationary phase of cell growth. The role of trigonelline in leguminous plants is discussed.
16. Fluorescent chemosensor for pyridine based on N-doped carbon dots.
Science.gov (United States)
Campos, B B; Abellán, C; Zougagh, M; Jimenez-Jimenez, J; Rodríguez-Castellón, E; Esteves da Silva, J C G; Ríos, A; Algarra, M
2015-11-15
Fluorescent carbon dots (CDs) and its nitrogen doped (N-CDs) nanoparticles have been synthesized from lactose as precursor using a bottom-up hydrothermal methodology. The synthesized nanoparticles have been characterized by elemental analysis, FTIR, Raman, TEM, DLS, XPS, and steady-state and life-time fluorescence. The synthesized carbon nanoparticles, CDs and N-CDs, have a size at about 7.7±2.4 and 50±15nm, respectively, and quantum yields of 8% (CDs) and 11% (N-CDs). These techniques demonstrated the effectiveness of the synthesis procedure and the functionalization of the CDs surface with amine and amide groups in the presence of NH3 in aqueous media. The effect of excitation wavelength and pH on the luminescent properties was studied. Under the optimal conditions, the nitrogen doped nanoparticles can be used as pyridine sensor in aqueous media because they show an enhancement of its fluorescence with a good linear relationship. The analytical method is simple, reproducible and very sensitive for pyridine determination. Copyright © 2015 Elsevier Inc. All rights reserved.
17. Synthesis of schiff bases of pyridine-4-carbaldehyde and their antioxidant and DNA binding studies
International Nuclear Information System (INIS)
Shamim, S.; Murtaza, S.; Nazar, M.F.
2016-01-01
A series of Schiff bases of pyridine-4-carbaldehyde with 3-aminobenzoic acid, 2-aminobenzoic acid, 4-aminobenzoic acid, 1,3-phenylenediamine, 1,2-phenylenediamine, 2-aminothiophenol, 4-aminoantipyrene, 2-aminophenol and naphthalene-1-amine was synthesized and compounds were characterized by FTIR, NMR and mass spectrometry. The synthesized compounds were evaluated for their antioxidant and DNA binding interaction studies. DPPH scavenging method was used to evaluate the antioxidant activities of synthesized Schiff bases at six gradually increasing concentrations of 0.5-5mg/ml. 2-((pyridin-4-ylmethylidene)amino)phenol came out to be the most efficient antioxidant at a concentration of 4mg/ml with 74% inhibition of free radicals generated by DPPH. The DNA binding interaction of the synthesized Schiff bases was determined using UV-Vis absorption titration method. Both the hypochromic and hyperchromic effects were observed along the series. The values for the binding constant (K) and free energy change (G) were calculated and most of the Schiff bases have high positive K values which indicate the efficient binding of Schiff bases with DNA. Molecular docking studies as carried out using PatchDock molecular algorithm software also indicated the high values for geometrical shape complementarity score suggesting the stabilities of Schiff bases/DNA complex. Docking studies also suggested the minor groove binding of the Schiff bases with DNA. Drug-likeness of the synthesized compounds was also tested in silico and the results are accordingly discussed. (author)
18. Sulfonated poly(ether sulfone)s containing pyridine moiety for PEMFC.
Science.gov (United States)
Jang, Hohyoun; Islam, Md Monirul; Lim, Youngdon; Hossain, Md Awlad; Cho, Younggil; Joo, Hyunho; Kim, Whangi; Jeon, Heung-Seok
2014-10-01
Sulfonated poly(ether sulfone)s with varied degree of sulfonation (DS) were prepared via post-sulfonation of synthesized pyridine based poly(ether sulfone) (PPES) using concentrated sulfuric acid as sulfonating agent. The DS was varied with different mole ratio of 4,4'-(2,2-diphenylethenylidene)diphenol, DHTPE in the polymer unit. PPES copolymers were synthesized by direct polycondensation of pyridine unit with bis-(4-fluorophenyl)-sulfone, 4, 4'-sulfonyldiphenol and DHTPE. The structure of the resulting PPES copolymer membranes with different sulfonated units were studied by 1H NMR spectroscopy and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymer with water. The ion exchange capacity (IEC) and proton conductivity were evaluated according to the increase of DS. The water uptake (WU) of the resulting membranes was in the range of 17-58%, compared to that of Nafion 211 28%. The membranes provided proton conductivities of 65-95 mS/cm in contrast to 103 mS/cm of Nafion 211.
19. Pyridine-2,6-diyl dinitroxides as room-temperature triplet ligands
Energy Technology Data Exchange (ETDEWEB)
Kawakami, Hinako; Tonegawa, Asato; Ishida, Takayuki, E-mail: [email protected] [Department of Engineering Science, The University of Electro-Communications, Tokyo (Japan)
2016-02-01
We have proposed tert-butyl 2-pyridyl nitroxide radicals as a promising paramagnetic chelating ligand, where the direct radical-metal bond leads to strong magnetic interaction. We successfully synthesized and isolated PyBN derivatives (pyridine-2,6-diyl bis(tert-butyl nitroxides)). The molecular and crystal structures of the target biradicals, MesPyBN, AntPyBN and tBuOPyBN were determined from the X-ray crystal structure analysis, which possess mesityl, 9-anthryl and tert-butoxy groups at the 5-position of the pyridine ring, respectively. The ground triplet state was characterized by means of SQUID susceptometry for each compound. On heating, the χ{sub m}T values of all the PyBN derivatives increased and reached a plateau at ca. 1.0 cm{sup 3} K mol{sup −1} at 300 K. It implies that biradicals behaved as triplet molecules even at room temperature, or 2J/k{sub B} >> 300 K. From the decay monitored in solution electron-spin resonance spectroscopy, MesPyBN was the most persistent, while tBuOPyBN was the most reactive, of the three.
20. Pyridine-type alkaloid composition affects bacterial community composition of floral nectar.
Science.gov (United States)
Aizenberg-Gershtein, Yana; Izhaki, Ido; Santhanam, Rakesh; Kumar, Pavan; Baldwin, Ian T; Halpern, Malka
2015-06-30
Pyridine-type alkaloids are most common in Nicotiana species. To study the effect of alkaloid composition on bacterial community composition in floral nectar, we compared the nicotine-rich wild type (WT) N. attenuata, the nicotine biosynthesis-silenced N. attenuata that was rich in anatabine and the anabasine-rich WT N. glauca plants. We found that the composition of these secondary metabolites in the floral nectar drastically affected the bacterial community richness, diversity and composition. Significant differences were found between the bacterial community compositions in the nectar of the three plants with a much greater species richness and diversity in the nectar from the transgenic plant. The highest community composition similarity index was detected between the two wild type plants. The different microbiome composition and diversity, caused by the different pyridine-type alkaloid composition, could modify the nutritional content of the nectar and consequently, may contribute to the change in the nectar consumption and visitation. These may indirectly have an effect on plant fitness.
1. Dithiafulvene-based organic sensitizers using pyridine as the acceptor for dye-sensitized solar cells
Energy Technology Data Exchange (ETDEWEB)
Cheng, Jun; Cao, Yaxiong; Liang, Xiaozhong; Zheng, Jingxia; Zhang, Fang [Ministry of Education Key Laboratory of Interface Science and Engineering in Advanced Materials, Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Wei, Shuxian; Lu, Xiaoqing [College of Science, China University of Petroleum, Qingdao, Shandong 266555 (China); Guo, Kunpeng, E-mail: [email protected] [Ministry of Education Key Laboratory of Interface Science and Engineering in Advanced Materials, Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Yang, Shihe, E-mail: [email protected] [Ministry of Education Key Laboratory of Interface Science and Engineering in Advanced Materials, Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)
2017-05-01
Three dithiafulvene-based metal-free organic sensitizers all using pyridine as the acceptor but with different π-bridges of phenyl (DTF-Py1), thienyl (DTF-Py2) and phenyl-thienyl (DTF-Py3) have been designed, synthesized and used as photosensitizers for dye-sensitized solar cells (DSCs). Introducing thienyl unit into the π-bridge, as well as extension of the π-bridge can dramatically improve their light harvesting ability and suppress the electron recombination, thus uplifting the performance of DSCs. The overall power conversion efficiency of DSC based on DTF-Py3 shows the highest efficiency of 2.61% with a short-circuit photocurrent density of 7.99 mA cm{sup -2}, an open-circuit photovoltage of 630 mV, and a fill factor of 0.52, under standard global AM 1.5 solar light condition. More importantly, the long-term stability of the DTF-Py3 based DSCs under 500 h light-soaking has been demonstrated. - Highlights: • Dithiafulvene sensitizers using pyridine ring as the acceptor were synthesized for the first time. • The power conversion efficiency of 2.61% was obtained for DTF-Py3 sensitized cell. • DTF-Py3 loaded TiO{sub 2} film shows improved light harvesting ability and suppressed electron recombination.
2. Aerobic granulation strategy for bioaugmentation of a sequencing batch reactor (SBR) treating high strength pyridine wastewater
Energy Technology Data Exchange (ETDEWEB)
Liu, Xiaodong; Chen, Yan [Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province (China); Zhang, Xin [Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province (China); Suzhou Institute of Architectural Design Co., Ltd, Suzhou 215021, Jiangsu Province (China); Jiang, Xinbai; Wu, Shijing [Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province (China); Shen, Jinyou, E-mail: [email protected] [Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province (China); Sun, Xiuyun; Li, Jiansheng; Lu, Lude [Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province (China); Wang, Lianjun, E-mail: [email protected] [Jiangsu Key Laboratory for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu Province (China)
2015-09-15
Abstract: Aerobic granules were successfully cultivated in a sequencing batch reactor (SBR), using a single bacterial strain Rhizobium sp. NJUST18 as the inoculum. NJUST18 presented as both a good pyridine degrader and an efficient autoaggregator. Stable granules with diameter of 0.5–1 mm, sludge volume index of 25.6 ± 3.6 mL g{sup −1} and settling velocity of 37.2 ± 2.7 m h{sup −1}, were formed in SBR following 120-day cultivation. These granules exhibited excellent pyridine degradation performance, with maximum volumetric degradation rate (V{sub max}) varied between 1164.5 mg L{sup −1} h{sup −1} and 1867.4 mg L{sup −1} h{sup −1}. High-throughput sequencing analysis exhibited a large shift in microbial community structure, since the SBR was operated under open condition. Paracoccus and Comamonas were found to be the most predominant species in the aerobic granule system after the system had stabilized. The initially inoculated Rhizobium sp. lost its dominance during aerobic granulation. However, the inoculation of Rhizobium sp. played a key role in the start-up process of this bioaugmentation system. This study demonstrated that, in addition to the hydraulic selection pressure during settling and effluent discharge, the selection of aggregating bacterial inocula is equally important for the formation of the aerobic granule.
3. Aerobic granulation strategy for bioaugmentation of a sequencing batch reactor (SBR) treating high strength pyridine wastewater
International Nuclear Information System (INIS)
Liu, Xiaodong; Chen, Yan; Zhang, Xin; Jiang, Xinbai; Wu, Shijing; Shen, Jinyou; Sun, Xiuyun; Li, Jiansheng; Lu, Lude; Wang, Lianjun
2015-01-01
Abstract: Aerobic granules were successfully cultivated in a sequencing batch reactor (SBR), using a single bacterial strain Rhizobium sp. NJUST18 as the inoculum. NJUST18 presented as both a good pyridine degrader and an efficient autoaggregator. Stable granules with diameter of 0.5–1 mm, sludge volume index of 25.6 ± 3.6 mL g −1 and settling velocity of 37.2 ± 2.7 m h −1 , were formed in SBR following 120-day cultivation. These granules exhibited excellent pyridine degradation performance, with maximum volumetric degradation rate (V max ) varied between 1164.5 mg L −1 h −1 and 1867.4 mg L −1 h −1 . High-throughput sequencing analysis exhibited a large shift in microbial community structure, since the SBR was operated under open condition. Paracoccus and Comamonas were found to be the most predominant species in the aerobic granule system after the system had stabilized. The initially inoculated Rhizobium sp. lost its dominance during aerobic granulation. However, the inoculation of Rhizobium sp. played a key role in the start-up process of this bioaugmentation system. This study demonstrated that, in addition to the hydraulic selection pressure during settling and effluent discharge, the selection of aggregating bacterial inocula is equally important for the formation of the aerobic granule
4. Ionic Liquids As Self-Assembly Guide for the Formation of Nanostructured Block Copolymer Membranes
KAUST Repository
Madhavan, Poornima; Sougrat, Rachid; Behzad, Ali Reza; Peinemann, Klaus-Viktor; Nunes, Suzana Pereira
2015-01-01
Nanostructured block copolymer membranes were manufactured by water induced phase inversion, using ionic liquids (ILs) as cosolvents. The effect of ionic liquids on the morphology was investigated, by using polystyrene-b-poly(4-vinyl pyridine) (PS
5. Crystal structures of nitrato-(2-[2-(1-pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazolo) aquacopper and chloro-(2-[2-phenyl(pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazolo) copper
Energy Technology Data Exchange (ETDEWEB)
Chumakov, Yu. M. [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of); Paholnitcaia, A. Yu. [State University of Moldova (Moldova, Republic of); Petrenko, P. A. [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of); Tsapkov, V. I., E-mail: [email protected] [State University of Moldova (Moldova, Republic of); Poirier, D. [Centre Hospitalier Universitaire de Quebec (Canada); Gulea, A. P. [State University of Moldova (Moldova, Republic of)
2015-01-15
Two crystal modifications of nitrato-(2-[2-(1-pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazolo) aquacopper (I and II) and two modifications of chloro-(2-[2-phenyl(pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazolo) copper (III and IV) have been synthesized and studied by X-ray diffraction. In structures I and II, the copper atoms coordinate a monodeprotonated molecule of the organic ligand, nitrate ions, and a water molecule. In crystals of I, the complexes are monomeric, whereas complexes II are linked via nitrate ions to form polymeric chains. In both structures the coordination polyhedron of the copper atom can be described as a distorted tetragonal bipyramid—(4 + 1 + 1) in I and (4 + 2) in II. These coordination polyherdra have different compositions. In structures III and IV, the metal atoms coordinate a monodeprotonated (2-[2-phenyl(pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazole molecule and chloride ions. In III the complex-forming ion has square-planar coordination geometry, whereas structure IV consists of centrosymmetric dimers with two bridging chlorine atoms. It was found that nitrato-(2-[2-(1-pyridine-2-ylethylidene)hydrazine]-1,3-benzothiazolo) aquacopper possesses antitumor activity.
6. Crystal structure of bis-[N-(2-hy-droxy-eth-yl)-N-methyl-dithio-carbamato-κ2S,S'](pyridine)-zinc(II) pyridine monosolvate and its N-ethyl analogue.
Science.gov (United States)
Poplaukhin, Pavel; Tiekink, Edward R T
2017-07-01
The common structural feature of the title compounds, [Zn(C 4 H 8 NOS 2 ) 2 (C 5 H 5 N)]·C 5 H 5 N (I) and [Zn(C 5 H 10 NOS 2 ) 2 (C 5 H 5 N)]·C 5 H 5 N (II), which differ by having di-thio-carbamate N-bound methyl (I) and ethyl (II) groups, is the coordination of each Zn II atom by two non-symmetrically chelating di-thio-carbamate ligands and by a pyridine ligand; in each case, the non-coordinating pyridine mol-ecule is connected to the Zn-containing mol-ecule via a (hy-droxy)O-H⋯N(pyridine) hydrogen bond. The resulting NS 4 coordination geometry is closer to a square-pyramid than a trigonal bipyramid in the case of (I), but almost inter-mediate between the two extremes in (II). The mol-ecular packing features (hy-droxy)O-H⋯O(hy-droxy) hydrogen bonds, leading to supra-molecular chains with a zigzag arrangement along [10-1] (I) or a helical arrangement along [010] (II). In (I), π-π [inter-centroid distances = 3.4738 (10) and 3.4848 (10) Å] between coordinating and non-coordinating pyridine mol-ecules lead to stacks comprising alternating rings along the a axis. In (II), weaker π-π contacts occur between centrosymmetrically related pairs of coordinating pyridine mol-ecules [inter-centroid separation = 3.9815 (14) Å]. Further inter-actions, including C-H⋯π(chelate) inter-actions in (I), lead to a three-dimensional architecture in each case.
7. Selective recovery of a pyridine derivative from an aqueous waste stream containing acetic acid and succinonitrile with solvent impregnated resins
NARCIS (Netherlands)
Bokhove, J.; Visser, T.J.; Schuur, Boelo; de Haan, A.B.
2015-01-01
Solvent impregnated resins (SIRs) were evaluated for the recovery of pyridine derivatives from an aqueous waste-stream containing also acetic acid and succinonitrile. For this purpose, a new solvent was developed, synthesized and impregnated in Amberlite XAD4. Sorption studies were used to determine
8. Post-synthetic modification of MIL-101(Cr) with pyridine for high-performance liquid chromatographic separation of tocopherols.
Science.gov (United States)
Yang, Fang; Yang, Cheng-Xiong; Yan, Xiu-Ping
2015-05-01
Effective separation of tocopherols is challenging and significant due to their structural similarity and important biological role. Here we report the post-synthetic modification of metal-organic framework (MOF) MIL-101(Cr) with pyridine for high-performance liquid chromatographic (HPLC) separation of tocopherols. Baseline separation of four tocopherols was achieved on a pyridine-grafted MIL-101(Cr) packed column within 10 min using hexane/isopropanol (96:4, v/v) as the mobile phase at a flow rate of 0.5 mL min(-1). The pyridine-grafted MIL-101(Cr) packed column gave high column efficiency (85,000 plates m(-1) for δ-tocopherol) and good precision (0.2-0.3% for retention time, 1.8-3.4% for peak area, 2.6-2.7% for peak height), and also offered much better performance than unmodified MIL-101(Cr) and commercial amino-bonded silica packed column for HPLC separation of tocopherols. The results not only show the promising application of pyridine-grafted MIL-101(Cr) as a novel stationary phase for HPLC separation of tocopherols, but also reveal a facile post-modification of MOFs to expand the application of MOFs in separation sciences. Copyright © 2015 Elsevier B.V. All rights reserved.
9. Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF5-substituted phenylboronic esters and iodobenzenes
Directory of Open Access Journals (Sweden)
George Iakobson
2015-08-01
Full Text Available Pyridine promotes dediazoniation of aryldiazonium tetrafluoroborates. The formed aryl radicals were trapped with B2pin2, iodine, or tetrahydrofuran to afford boronic esters, iodobenzenes and benzenes, respectively. The application to the synthesis of (pentafluorosulfanylphenylboronic esters, iodo(pentafluorosulfanylbenzenes and (pentafluorosulfanylbenzene is shown.
10. Poly[propane-1,3-diammonium [cuprate(II-bis(μ2-pyridine-2,3-dicarboxylato] trihydrate
Directory of Open Access Journals (Sweden)
Shabnam Hooshmand
2008-02-01
Full Text Available The title polymeric compound {(C3H12N2[Cu(C7H3NO42]·3H2O}n or {(pnH2[Cu(py-2,3-dc2]·3H2O}n (pn is propane-1,3-diamine and py-2,3-dcH2 is pyridine-2,3-dicarboxylic acid, was synthesized by reaction of copper(II chloride dihydrate with a proton-transfer compound, propane-1,3-diammonium pyridine-2,3-dicarboxylate or (pnH2(py-2,3-dc, in aqueous solution. The anion is a six-coordinate complex (site symmetry overline{1}, with a distorted octahedral geometry around CuII, consisting of two bidentate pyridine-2,3-dicarboxylate groups and two O atoms of bridging ligands from (py-2,3-dc2− fragments, which are located in trans positions. The (pnH22+ cation is disordered over two sites by the center of inversion. Intermolecular hydrogen bonds, π–π [centroid–centroid distances of 3.539 (3 Å] and C—O...π stacking interactions [O...Cg = 3.240 (5 Å; Cg is the center of the pyridine ring], connect the various components into a supramolecular structure.
11. Formation of mono- and multilayers of metal complexes of 4-(((10,12-pentacosadiynoyl)oxy)methyl)pyridine
NARCIS (Netherlands)
Werkman, P J; Wilms, H; Wieringa, R H; Schouten, A J
1998-01-01
The monolayer properties of the amphiphile, 4-(((10,12-pentacosadiynoyl)oxy)methyl)pyridine have been studied by measuring the surface pressure-area isotherms. The amphiphile forms stable monolayers at the air-water interface and protonation of the monolayers occurs at pH values of 3.00 or lower.
12. Rotational barriers of 1,3-substitute pyridines and benzenes as models for the NAD+/NADH coenzyme
NARCIS (Netherlands)
Vanhommerig, S.A.M.; Meier, R.J.; Sluyterman, L.A.A.E.; Meijer, E.M.
1994-01-01
The NAD+/NADH coenzyme is involved in many enzyme-catalysed oxidation-reduction reactions. In order to obtain better insight in the catalytic mechanism of NAD+/NADH dependent dehydrogenases, conformational studies of 1,3-substituted pyridines and benzenes were carried out, using ab initio,
13. Mechanistic Dichotomy in the Asymmetric Allylation of Aldehydes with Allyltrichlorosilanes Catalyzed by Chiral Pyridine N-Oxides
Czech Academy of Sciences Publication Activity Database
Malkov, A. V.; Stončius, S.; Bell, M.; Castelluzzo, F.; Ramírez-López, P.; Biedermannová, Lada; Langer, V.; Rulíšek, Lubomír; Kočovský, P.
2013-01-01
Roč. 19, č. 28 (2013), s. 9167-9185 ISSN 0947-6539 R&D Projects: GA MŠk LC512 Institutional support: RVO:61388963 ; RVO:86652036 Keywords : allylation * allylsilanes * calculations * organocatalysis * pyridine N-oxides Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.696, year: 2013
14. Synthesis and Characterization of 2-Phenylimidazo[1,2-a]pyridine: A Privileged Structure for Medicinal Chemistry
Science.gov (United States)
Santaniello, Brandi S.; Price, Matthew J.; Murray, James K., Jr.
2017-01-01
A straightforward synthesis of 2-phenylimidazo[1,2-a]pyridine is described. The reaction is designed to demonstrate to students the preparation of a bridged N-heterocycle, in which the heteroatom occupies a bridgehead position. The product is obtained in moderate to high yield and is highly crystalline. The compound can be purified either by…
15. Synthesis and luminescence properties of europium and terbium complexes with pyridine- or bipyridine-linked oligothiophene ligand
International Nuclear Information System (INIS)
Liu Ping; Huang Mingsheng; Pan Wanzhang; Zhang Yamin; Hu Jianhua; Deng Wenji
2006-01-01
With an aim to develop novel luminescence materials, europium and terbium complexes of 2,5-(2-thiophene)-pyridine (TPY) and 5,5'-bis(5-(2,2'-bithiophene))-2,2'-bipyridine (B2TBPY) were synthesized, and their luminescence properties studied. The complexes exhibit ligand-sensitized emission, which is typical of Eu(III) and Tb(III) ions
16. Study of New Thiazole Based Pyridine Derivatives as Potential Corrosion Inhibitors for Mild Steel: Theoretical and Experimental Approach
Directory of Open Access Journals (Sweden)
T. K. Chaitra
2016-01-01
Full Text Available Three new thiazole based pyridine derivatives 5-(4-methoxy-phenyl-thiazole-2-carboxylic acid pyridin-2-ylmethylene-hydrazide (2-MTPH, 5-(4-methoxy-phenyl-thiazole-2-carboxylic acid pyridin-3-ylmethylene-hydrazide (3-MTPH, and 5-(4-methoxy-phenyl-thiazole-2-carboxylic acid pyridin-4-ylmethylene-hydrazide (4-MTPH were synthesized and characterized. Corrosion inhibition performance of the prepared compounds on mild steel in 0.5 M HCl was studied using gravimetric, potentiodynamic polarisation, and electrochemical impedance techniques. Inhibition efficiency has direct relation with concentration and inverse relation with temperature. Thermodynamic parameters for dissolution and adsorption process were evaluated. Polarisation study reveals that compounds act as both anodic and cathodic inhibitors with emphasis on the former. Impedance study shows that decrease in charge transfer resistance is responsible for effective protection of steel surface by inhibitors. The film formed on the mild steel was investigated using FTIR, SEM, and EDX spectroscopy. Quantum chemical parameters like EHOMO, ELUMO, ΔE, hardness, softness, and ionisation potential were calculated. Higher value of EHOMO and lower value of ΔE indicate the better inhibition efficiency of the compounds. Lower ionisation potential of inhibitors indicates higher reactivity and lower chemical stability.
17. Formation of Bonded Exciplex in the Excited States of Dicyanoanthracene-Pyridine System : Time Dependent Density Functional Theory Study
NARCIS (Netherlands)
Setiawan, D.; Sethio, D.; Martoprawiro, M.A.; Filatov, M.; Gaol, FL; Nguyen, QV
2012-01-01
Strong quenching of fluorescence was recently observed in pyridine solutions of 9,10-dicyanoanthracene chromophore. It was hypothesized that quenching may be attributed to the formation of bound charge transfer complexes in the excited states of the molecules. In this work, using time-dependent
18. Activation and desensitization of peripheral muscle and neuronal nicotinic acetylcholine receptors by selected, naturally-occurring pyridine alkaloids
Science.gov (United States)
Teratogenic alkaloids can cause developmental defects due to inhibition of fetal movement that results from desensitization of fetal muscletype nicotinic acetylcholine receptors (nAChRs). We investigated the ability of two known teratogens, the piperidinyl-pyridine anabasine and its 1,2-dehydropiper...
19. Dihydrogen phosphate-water tape and layers vs dihydrogen phosphate layers tuned by hydrophobic isomeric pyridine-diamine functionalized molecules
Science.gov (United States)
Huang, Jing; Liu, Tong-Peng; Huo, Li-Hua; Deng, Zhao-Peng; Gao, Shan
2017-01-01
Assembly of six isomeric pyridine-diamine-based molecules, N,N‧-bis(pyridin-4-ylmethyl)ethane-1,2-diamine (M1), N,N‧-bis(pyridin-3-ylmethyl)ethane-1,2-diamine (M2), N,N‧-bis(pyridin-2-ylmethyl)ethane-1,2-diamine (M3), N,N‧-bis(pyridin-4-ylmethyl)propane-1,3-diamine (M4), N,N‧-bis(pyridin-3-ylmethyl)propane-1,2-diamine (M5), and N,N‧-bis(pyridin-2-ylmethyl)propane-1,3-diamine (M6), with phosphoric acid (H3PO4) in different ratio (1:2 and 1:4), leads to the formation of nine salts, H2M12+·2H2PO4-·4H2O (1), H2M22+·2H2PO4-·2H2O (2), H2M32+·2H2PO4-·2H2O (3), H4M14+·4H2PO4- (4), H4M24+·4H2PO4- (5), H4M34+·4H2PO4- (6), H2M42+·2H2PO4-·3H2O (7), 2H2M52+·4H2PO4-·2H3PO4 (8), and H2M62+·2H2PO4- (9), which have been characterized by elemental analysis, IR, TG, PL, powder and single-crystal X-ray diffraction. Structural analyses indicate that hydrogen-bonding patterns of H2PO4- anions, conformation of protonated cations can effectively influence the supramolecular architectures through diverse non-covalent interactions. Hydrous salts 1-3 and 7 present 2D and 3D host-guest supramolecular networks, in which the connection of H2PO4- anions and water molecules generates diverse tape and layer motifs. H2PO4- anions in anhydrous salts 4-6 interconnect with each other through hydrogen bonds to form two types of layers, which are joined by discrete H4M4+ cations into 3D inorganic-organic hybrid supramolecular networks. Salts 8-9 also present 2D and 3D host-guest supramolecular networks where the interconnection of H2PO4- anions and its combination with H3PO4 molecules leads to diverse layers. Luminescent analyses indicate that salts 1-9 exhibit violet and blue emission maximum in the range of 390-467 nm at room temperature.
20. Synthesis and characterization of two novel pyridine-containing framework gallium ethylenediphosphonates
International Nuclear Information System (INIS)
Yuan Zhanhui; Clegg, William; Attfield, Martin P.
2006-01-01
Two novel gallium diphosphonates, (C 5 H 5 N)Ga 3 F(O 3 PC 2 H 4 PO 3 ) 2 (I) (triclinic, P-1, a=8.2880(12) A, b=11.7197(16) A, c=11.7601(17) A, α=71.589(3) o , β=70.577(3) o , γ=77.313(3) o , V=1013.7(2) A 3 , Z=2, R 1 =0.0352, wR 2 =0.0980) and (C 5 H 5 NH) 2 [Ga 4 F 2 (O 3 PC 2 H 4 PO 3 ) 3 ] (II) (triclinic, P-1, a=8.670(4) A, b=9.742(3) A, c=10.406(2) A, α=81.44(3) o , β=65.83(5) o , γ=67.16(3) o , V=739.0(4) A 3 , Z=2, R 1 =0.0600, wR 2 =0.1495) have been synthesised by solvothermal methods in the presence of pyridine and their structures determined using single-crystal X-ray diffraction data. Both compounds I and II are composed of various Ga-centered polyhedra and ethylenediphosphonate groups that link together to form framework materials with one- and two-dimensional channel systems, respectively. The two structures are formed in the presence of structure-directing pyridine molecules that are directly bound to some of the Ga atoms in I, and are protonated as pyridinium cations in II. Compounds I has a charge-neutral framework, while compound II has an anionic framework. Both materials provide rare examples of organically structure-directed framework metal diphosphonate materials. - Graphical abstract: (C 5 H 5 N)Ga 3 F(O 3 PC 2 H 4 PO 3 ) 2 (I) and (C 5 H 5 NH) 2 [Ga 4 F 2 (O 3 PC 2 H 4 PO 3 ) 3 ] (II) are novel gallium diphosphonate materials composed of Ga-centered polyhedra and ethylenediphosphonate groups that link together to form framework materials with one- and two-dimensional channel systems, respectively. The two structures are formed in the presence of structure-directing pyridine molecules or pyridinium cations and are examples of organically structure-directed framework metal diphosphonates
1. One-photon mass-analyzed threshold ionization (MATI) spectroscopy of pyridine: Determination of accurate ionization energy and cationic structure
Energy Technology Data Exchange (ETDEWEB)
Lee, Yu Ran; Kang, Do Won; Kim, Hong Lae, E-mail: [email protected], E-mail: [email protected]; Kwon, Chan Ho, E-mail: [email protected], E-mail: [email protected] [Department of Chemistry and Institute for Molecular Science and Fusion Technology, College of Natural Sciences, Kangwon National University, Chuncheon 200-701 (Korea, Republic of)
2014-11-07
Ionization energies and cationic structures of pyridine were intensively investigated utilizing one-photon mass-analyzed threshold ionization (MATI) spectroscopy with vacuum ultraviolet radiation generated by four-wave difference frequency mixing in Kr. The present one-photon high-resolution MATI spectrum of pyridine demonstrated a much finer and richer vibrational structure than that of the previously reported two-photon MATI spectrum. From the MATI spectrum and photoionization efficiency curve, the accurate ionization energy of the ionic ground state of pyridine was confidently determined to be 73 570 ± 6 cm{sup −1} (9.1215 ± 0.0007 eV). The observed spectrum was almost completely assigned by utilizing Franck-Condon factors and vibrational frequencies calculated through adjustments of the geometrical parameters of cationic pyridine at the B3LYP/cc-pVTZ level. A unique feature unveiled through rigorous analysis was the prominent progression of the 10 vibrational mode, which corresponds to in-plane ring bending, and the combination of other totally symmetric fundamentals with the ring bending overtones, which contribute to the geometrical change upon ionization. Notably, the remaining peaks originate from the upper electronic state ({sup 2}A{sub 2}), as predicted by high-resolution photoelectron spectroscopy studies and symmetry-adapted cluster configuration interaction calculations. Based on the quantitatively good agreement between the experimental and calculated results, it was concluded that upon ionization the pyridine cation in the ground electronic state should have a planar structure of C{sub 2v} symmetry through the C-N axis.
2. N-acetyltransferase-dependent activation of 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine: formation of 2-amino-1-methyl-6-(5-hydroxy)phenylimidazo [4,5-b]pyridine, a possible biomarker for the reactive dose of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine
DEFF Research Database (Denmark)
Frandsen, Henrik Lauritz; Alexander, J.
2000-01-01
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a mutagenic and carcinogenic heterocyclic amine formed during ordinary cooking. PhIP is metabolically activated to the ultimate mutagenic metabolite by CYP P450-mediated N-hydroxylation followed by phase II esterification, Incubation of N...
3. Poly[μ2-aqua-aqua-μ4-pyridine-2,4-dicarboxylato-strontium
Directory of Open Access Journals (Sweden)
Zohreh Derikvand
2009-08-01
Full Text Available In the title polymeric complex, [Sr(C7H3NO4(H2O2]n, the SrII atom is eight-coordinated by four O atoms and one N atom of four pyridine-2,4-dicarboxylate (py-2,4-dc ligands and three O atoms of three coordinated water molecules in a dodecahedral geometry. These units are connected via the carboxylate O atoms and water molecules, building polymeric layers parallel to (100. In the crystal structure, non-covalent interactions consisting of O—H...O hydrogen bonds and π–π stacking interactions [centroid–centroid distances = 3.862 (17 and 3.749 (17 Å] connect the various components, forming a three-dimensional structure.
KAUST Repository
Winston, Matthew S.
2014-10-01
A series of complexes of the type (PNP-H2)PdX2 (X=Cl, Br, I) have been synthesized, where PNP-H2 is a bis(secondary)phosphine ligand linked by a pyridine, 2,6-(2\\'-(Ph(H)P)(C6H4))2(C5H3N). Due to chirality at phosphorus, the parent ligand exists as a mixture of nearly equivalent rac and meso diastereomers non-interconverting at room temperature. When ligated to Pd(II) halides, however, the diastereomeric ratio is dependent upon the halide. The chloro, bromo, and iodo complexes have been characterized crystallographically. Conformationally similar meso diastereomers of each dihalide are roughly C s symmetric in the solid state, while the rac diastereomers (identified only for X=Br, I) show substantially different solid-state conformations. © 2014 Elsevier B.V.
5. Bis[(E-N-(pyridin-3-ylmethylidenehydroxylamine-κN1]silver(I perchlorate
Directory of Open Access Journals (Sweden)
Jing Xu
2012-06-01
Full Text Available Each of the ions in the title salt, [Ag(C6H6N2O2]ClO4, is completed by the application of crystallographic twofold symmetry. The AgI atom is coordinated by two pyridine N atoms in an almost linear fashion [N—Ag—N = 170.0 (2°], with the T-shaped coordination geometry being completed by a weakly associated perchlorate-O atom. Supramolecular zigzag chains along [100] mediated by O—H...N hydrogen bonds [as parts of R22(6 loops] feature in the crystal packing. The perchlorate O atoms are disordered over two sets of sites in a statistical ratio.
6. Pyrrole-Pyridine and Pyrrole-Naphthyridine Hosts for Anion Recognition
Directory of Open Access Journals (Sweden)
M. Angeles García
2015-05-01
Full Text Available The association constants of the complexes formed by two hosts containing pyrrole, amide and azine (pyridine and 1,8-naphthyridine groups and six guests, all monoanions (Cl−, CH3CO2−, NO3−, H2PO4−, BF4−, PF6−, have been determined using NMR titrations. The X-ray crystal structure of the host N2,N5-bis(6-methylpyridin-2-yl-3,4-diphenyl-1H-pyrrole- 2,5-dicarboxamide (1 has been solved (P21/c monoclinic space group. B3LYP/6-31G(d,p and calculations were carried out in an attempt to rationalize the trends observed in the experimental association constants.
7. catena-Poly[[[aquapyridinezinc(II]-μ2-3,3′-(p-phenylenediacrylato] pyridine solvate
Directory of Open Access Journals (Sweden)
Dongpo Su
2010-09-01
Full Text Available The title compound, {[Zn(C12H8O4(C5H5N(H2O]·C5H5N}n, has been prepared by hydrothermal reaction. The ZnII atom is six-coordinated by four carboxylate O atoms of two p-phenylenediacrylate (ppda2− ligands, one N atom of a pyridine molecule and one O atom of a water molecule in a distorted octahedral environment. The carboxylate groups of the ppda2− anions are in a bridging–chelating mode, in which two O atoms chelate one Zn2+ ion. These connections result in an extended chain structure. Parallel packing of the chains forms a two-dimensional network with intermolecular edge-to-face interactions. Further linkages between the layers through O—H...O hydrogen-bonding interactions result in a three-dimensional supramolecular architecture with one-dimensional rectanglar channels.
8. Aquabis(4-methylbenzoato-κO;κ2O,O′-bis(pyridine-κNnickel(II
Directory of Open Access Journals (Sweden)
Li-Li Ji
2008-04-01
Full Text Available In the title mononuclear complex, [Ni(C8H7O22(C5H5N2(H2O], the NiII atom is in a distorted octahedral arrangement, coordinated by three carboxylate O atoms from one bidentate 4-methylbenzoate ligand and one monodentate 4-methylbenzoate ligand, two N atoms from pyridine ligands, axially positioned, and a water molecule. The equatorially positioned water molecule and uncoordinated carboxylate O atom form an intramolecular hydrogen bond. An intermolecular O—H...O hydrogen bond between the coordinated water molecule and carboxylate O atom of the 4-methylbenzoate ligand forms infinite chains along the b axis. These chains are connected by C—H...π interactions.
9. Ruthenium complexes containing 2-(2-nitrosoaryl)pyridine: structural, spectroscopic, and theoretical studies.
Science.gov (United States)
Chan, Siu-Chung; Cheung, Ho-Yuen; Wong, Chun-Yuen
2011-11-21
Ruthenium complexes containing 2-(2-nitrosoaryl)pyridine (ON(^)N) and tetradentate thioether 1,4,8,11-tetrathiacyclotetradecane ([14]aneS4), [Ru(ON(^)N)([14]aneS4)](2+) [ON(^)N = 2-(2-nitrosophenyl)pyridine (2a), 10-nitrosobenzo[h]quinoline (2b), 2-(2-nitroso-4-methylphenyl)pyridine, (2c), 2-(2-nitrosophenyl)-5-(trifluoromethyl)pyridine (2d)] and analogues with the 1,4,7-trithiacyclononane ([9]aneS3)/tert-butylisocyanide ligand set, [Ru(ON(^)N)([9]aneS3)(C≡N(t)Bu)](2+) (4a and 4b), have been prepared by insertion of a nitrosonium ion (NO(+)) into the Ru-aryl bond of cyclometalated ruthenium(II) complexes. The molecular structures of the ON(^)N-ligated complexes 2a and 2b reveal that (i) the ON(^)N ligands behave as bidentate chelates via the two N atoms and the bite angles are 86.84(18)-87.83(16)° and (ii) the Ru-N(NO) and N-O distances are 1.942(5)-1.948(4) and 1.235(6)-1.244(5) Å, respectively. The Ru-N(NO) and N-O distances, together with ν(N═O), suggest that the coordinated ON(^)N ligands in this work are neutral moiety (ArNO)(0) rather than monoanionic radical (ArNO)(•-) or dianion (ArNO)(2-) species. The nitrosated complexes 2a-2d show moderately intense absorptions centered at 463-484 nm [ε(max) = (5-6) × 10(3) dm(3) mol(-1) cm(-1)] and a clearly discriminable absorption shoulder around 620 nm (ε(max) = (6-9) × 10(2) dm(3) mol(-1) cm(-1)), which tails up to 800 nm. These visible absorptions are assigned as a mixing of d(Ru) → ON(^)N metal-to-ligand charge-transfer and ON(^)N intraligand transitions on the basis of time-dependent density functional theory (TD-DFT) calculations. The first reduction couples of the nitrosated complexes range from -0.53 to -0.62 V vs Cp(2)Fe(+/0), which are 1.1-1.2 V less negative than that for [Ru(bpy)([14]aneS4)](2+) (bpy = 2,2'-bipyridine). Both electrochemical data and DFT calculations suggest that the lowest unoccupied molecular orbitals of the nitrosated complexes are ON(^)N-centered. Natural population
10. Amplification of light emission of chiral pyridine Eu(III) complex by copper nanoparticles
Energy Technology Data Exchange (ETDEWEB)
Reisfeld, Renata; Levchenko, Viktoria [Institute of Chemistry, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904 (Israel); Piccinelli, Fabio; Bettinelli, Marco [Laboratorio Materiali Luminescenti, DB, Universita di Verona and INSTM, UdR Verona, Strada Le Grazie 15, 37134 Verona (Italy)
2016-02-15
We outline the applications of lanthanides luminescence in a number of modern fields. The intensity of the luminescence of the expensive lanthanides can be increased by their interaction with nanoparticles of inexpensive copper. As a typical example the chiral pyridine-based Eu{sup 3+} complex was incorporated into amorphous films of polyvinyl alcohol with hydroxyethyl cellulose. The luminescence intensity of the complex is increased by three hundred percent by its interaction with copper nanoparticles. The synthesis and steady state spectroscopy of the materials are presented. - Highlights: • Nanoparticles of copper were for the first time synthesized at 80 °C. • Copper NPs were incorporated with a luminescent Eu{sup 3+} complex in a polymeric matrix. • The films produced were characterized by photoluminescence spectroscopy. • The luminescence of Eu{sup 3+} complex with Cu NPs is 3 times higher than the original one.
11. N-(3-{[(Z-(3-Hydroxy-4-methylphenylimino]methyl}pyridin-2-ylpivalamide
Directory of Open Access Journals (Sweden)
Şehriman Atalay
2016-03-01
Full Text Available The molecular structure of the title compound, C18H21N3O2, contains pivalamide, pyridin and hydroxy-methylphenyl moieties. The whole molecule is not planar, the dihedral angle between the benzene rings being 34.84 (7°. The molecular conformation is stabilized by an intramolecular N—H...N hydrogen bond. In the crystal, molecules are linked by O—H...O, O—H...N and C—H...O hydrogen bonds. The C and H atoms of the tert-butyl group disordered over two sets of sites with an occupancy ratio of 0.692 (5:0.308 (5.
12. Effective transport properties for the pyridine-granular activated carbon adsorption system
Directory of Open Access Journals (Sweden)
S. A. Baz-Rodríguez
2012-09-01
Full Text Available In this work, the kinetics of pyridine adsorption onto granular activated carbon was studied from the point of view of an up-scaling process by using the method of volume averaging. The pore and surface effective diffusivities were estimated by supposing simple microscale geometries (ordered media of cylinders and spheres and those of images processed from SEM (Scanning Electron Microscopy micrographs. In addition, as a rough estimate, the point surface diffusivity is reported. The results revealed that the up-scaled diffusional model satisfactorily interpreted the concentration decay curves and the effective diffusivity was found to be an increasing function of the concentration, mainly due to the contribution of surface diffusion. In general, the diffusivity coefficients involved in the adsorption system are related through the expression molecular diffusivity = 22 ï‚' point surface diffusivity = 5/2 x‚' pore effective diffusivity = 1/12 x ‚' surface effective diffusivity.
13. Investigations of the reactivity of pyridine carboxylic acids with diazodiphenylmethane in protic and aprotic solvents.
Directory of Open Access Journals (Sweden)
ALEKSANDAR D. MARINKOVIC
2005-04-01
Full Text Available Rate constants for the reaction of diazodiphenylmethane with isomeric pyridine carboxylic acids were determined in chosen protic and aprotic solvents at 30 °C, using the well known UV spectrophotometric method. The values of the rate constants of the investigated acids in protic solvents were higher than those in aprotic solvents. The second order rate constants were correlated with solvent parameters using the Kamlet-Taft solvatochromic equation in the form: log k = log k0 + sp* + aa + bb . The correlation of the obtained kinetic data were performed by means of multiple linear regression analysis taking appropriate solvent parameters. The signs of the equation coefficients were in agreement with the postulated reaction mechanism. The mode of the influence of the solvent on the reaction rate in all the investigated acids are discussed on the basis of the correlation results.
14. 1,3-Dicyclohexyl-3-[(pyridin-2-ylcarbonyl]urea monohydrate from synchrotron radiation
Directory of Open Access Journals (Sweden)
Solange M. S. V. Wardell
2011-10-01
Full Text Available The title urea derivative crystallizes as a monohydrate, C19H27N3O2·H2O. The central C3N grouping is almost planar (r.m.s. deviation = 0.0092 Å, and the amide and pyridine groups are substantially twisted out this plane [dihedral angles = 62.80 (12 and 34.98 (10°, respectively]. Supramolecular double chains propagating along the b-axis direction feature in the crystal packing whereby linear chains sustained by N—H...O hydrogen bonds formed between the amide groups are linked by helical chains of water molecules (linked by O—H...O hydrogen bonds. The H atom that participates in these water chains is disordered over two positions of equal occupancy. The double chains are connected into a two-dimensional array by C—H...O contacts and the layers stack along the a axis.
15. Identification of combustion intermediates in low-pressure premixed pyridine/oxygen/argon flames.
Science.gov (United States)
Tian, Zhenyu; Li, Yuyang; Zhang, Taichang; Zhu, Aiguo; Qi, Fei
2008-12-25
Combustion intermediates of two low-pressure premixed pyridine/oxygen flames with respective equivalence ratios of 0.56 (C/O/N = 1:4.83:0.20) and 2.10 (C/O/N = 1:1.29:0.20) have been identified with tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry techniques. About 80 intermediates in the rich flame and 60 intermediates in the lean flame, including nitrogenous, oxygenated, and hydrocarbon intermediates, have been identified by measurements of photoionization mass spectra and photoionization efficiency spectra. Some radicals and new nitrogenous intermediates are identified in the present work. The experimental results are useful for studying the conversion of volatile nitrogen compounds and understanding the formation mechanism of NO(x) in flames of nitrogenous fuels.
16. The simple production of nonsymmetric quaterpyridines through Kröhnke pyridine synthesis
Directory of Open Access Journals (Sweden)
Isabelle Sasaki
2015-09-01
Full Text Available Quaterpyridines have been demonstrated to be useful building blocks in metallo-supramolecular chemistry; however, their synthesis requires the preparation of sensitive building blocks. We present here three examples of nonsymmetric quaterpyridines that were easily obtained in yields of 70–85% by condensation of commercially available enones with 6-acetyl-2,2’:6’,2’’-terpyridine through a Kröhnke pyridine synthesis. Easy access to 6-acetyl-2,2’:6’,2’’-terpyridine starting from 2,6-diacetylpyridine and 2-acetylpyridine is described. The X-ray analysis of a chiral quaterpyridine and its Pt(II complex is presented.
17. Distinct sesquiterpene pyridine alkaloids from in Salvadoran and Peruvian Celastraceae species.
Science.gov (United States)
Callies, Oliver; Núñez, Marvin J; Perestelo, Nayra R; Reyes, Carolina P; Torres-Romero, David; Jiménez, Ignacio A; Bazzocchi, Isabel L
2017-10-01
As part of a bioprospecting program aimed at the discovery of undescribed natural products from Salvadoran and Peruvian flora, the phytochemical investigations of four Celastraceae species, Celastrus vulcanicola, Maytenus segoviarum, Maytenus jeslkii, and Maytenus cuzcoina, were performed. The current study reports the isolation and structural characterization of five previously undescribed macrolide sesquiterpene pyridine alkaloids, named vulcanicoline-A, cuzcoinine, vulcanicoline-B, jelskiine, and vulcanicoline-C, along with sixteen known alkaloids. The structures of the alkaloids were established by spectrometric and extensive 1D and 2D NMR spectroscopic analysis, including COSY, HSQC, HMBC, and ROESY experiments. The absolute configurations of alkaloids were proposed based on optical rotation sign, and biogenetic considerations. This study represents the first phytochemical analysis of Maytenus segoviarum. Copyright © 2017 Elsevier Ltd. All rights reserved.
18. Diaquabis(pyridine-2-carboxylato-κ2N,Omanganese(II dimethylformamide hemisolvate
Directory of Open Access Journals (Sweden)
Irina A. Golenya
2011-11-01
Full Text Available There are two crystallographically independent complex molecules with very similar geometries in the unit cell of the title compound, [Mn(C6H4NO22(H2O2]·0.5C3H7NO. The central ion is situated in a distorted octahedral environment of two N- and four O-donor atoms from two pyridine-2-carboxylate ligands and two cis-disposed water molecules. The carboxylate ligands are coordinated in a chelate fashion with the formation of two five-membered rings. In the crystal, the complex molecules are connected by O—H...O hydrogen bonds between the coordinated water molecules and the uncoordinated carboxylate O atoms, thus forming hydrogen-bonded walls disposed perpendicularly to the bc plane.
19. Tetrakis[bis(pyridin-2-ylamine-κN2](nitrato-κOsilver(I
Directory of Open Access Journals (Sweden)
Yuliia Parashchenko
2014-02-01
Full Text Available In the title complex, [Ag(NO3(C10H9N34], the nitrate ligand is found to be disordered over two sets of positions, with occupancy factors of 0.473 (5 and 0.527 (5. The AgI ion is located in a square-pyramidal coordination environment formed by four N atoms from four bis(pyridin-2-ylamine ligands and one O atom from a nitrate ligand. Weak interactions between the AgI ions and the nitrate anions acting in a monodentate mode [Ag...O = 2.791 (13 and 2.816 (9 Å for the major component of the nitrate ligand, and 2.865 (8 and 2.837 (8 Å for the minor component] link the complex molecules into a chain along [001]. N—H...O hydrogen bonds are observed.
20. Syntheses and a Solid State Structure of a Dinuclear Molybdenum(V Complex with Pyridine
Directory of Open Access Journals (Sweden)
Jon Zubieta
2010-01-01
Full Text Available A mononuclear complex [MoOCl4(H2O]− readily forms a metal−metal bonded {Mo2O4}2+ core. A high content of pyridine in the reaction mixture prevents further aggregation of dinuclear cores into larger clusters and a neutral, dinuclear complex with the [Mo2O4Cl2(Py4] composition is isolated as a product. Solid state structures of two compounds containing this complex, [Mo2O4Cl2(Py4]·2.25Py (1 and [Mo2O4Cl2(Py4]·1.5PyHCl (2, were investigated by X-ray crystallography.
1. Polymer Concentration-Controlled Substrate Specificity in Solvolysis of p-Nitrophenyl Alkanoates Catalyzed by 4-(Dialkylamino)pyridine- Functionalized Polymer in Aqueous Methanol Solution
National Research Council Canada - National Science Library
Wang, Guang-Jia
1996-01-01
The substrate specificity in solvolysis reactions of p-nitrophenyl alkanoates 2 (n=2-18) catalyzed by 4-(dialkylamino)pyridine-functionalized polymer 1 can be controlled by the concentration of 1 in 1...
2. Synthesis and biological evaluation of certain 2-H-Pyran-2-Ones and some derived 1-H-Pyridin-2-One analogs as antimicrobial agents
International Nuclear Information System (INIS)
2008-01-01
Pyran-2-one and pyridine-2-one analogs are known to be biological versatile compounds possessing variety of pharmacological activities. Some 4-(4-nitrophenyl)-5, 6-diphenyl-pyran-2-ones and their 1H-pyridin-2-oneanalogs were synthesized and evaluated for their in vitro intermediates and target compounds were discussed. The results evaluated that some compounds exhibited promising antibacterial and antifungal activities. Compound 8; 1-hydroxy-4-(4-nitrophenyl)-5, 6-diphenyl-1H-pyridin-2-one; showed the most potent broad spectrum antimicrobial activity. 1-Methyl-4-(4-nitrophenyl)-5, 6-diphenyl-1H-pyridin-2-thione 12; was able to exert weak growth inhibitory effect against the Mycobacterium tuberculosis. (author)
3. New 1-hydroxy-1,1-bisphosphonates derived from 1H-pyrazolo[3,4-b]pyridine: synthesis and characterization
Energy Technology Data Exchange (ETDEWEB)
Teixeira, Fatima C.; Lucas, Carla; Curto, M. Joao M., E-mail: [email protected] [Laboratorio Nacional de Energia e Geologia, Lisboa (Portugal); Neves, M. [Instituto Superior Tecnico, Instituto Tecnologico e Nuclear (IST/ITN), Campus Tecnologico e Nuclear, Universidade Tecnica de Lisboa, Sacavem (Portugal); Duarte, M. Teresa; Andre, Vania; Teixeira, Antonio P.S. [Centro de Quimica Estrutural, Instituto Superior Tecnico, Universidade Tecnica de Lisboa (Portugal)
2013-07-15
A number of 1H-pyrazolo[3,4-b]pyridine derivatives, starting from 2-chloro-3-formyl pyridine, was synthesized to obtain new 1-hydroxybisphosphonates, a class of compounds with potential biological interest. Spectroscopic data were used to characterize all compounds and to identify N-1 and N-2 regioisomers, and mono- and bisphosphonates derivatives. X-ray diffractometry studies of compound 7a confirmed the proposed structure. (author)
4. Synthesis of a novel series of 4-arylpiperazinyl derivatives linked to a 2-(pyridin-3-yl)-1H-benzimidazole as new Delavirdine analogues
International Nuclear Information System (INIS)
Pessoa-Mahana, David; Nunez, Andres; Espinosa, Christian; Mella-Raipn, Jaime; Pessoa-Mahana, Hernan
2010-01-01
The synthesis of a series of substituted arylpiperazines linked to a 2-(pyridin-3-yl)-1H-benzo[d]imidazole scaffold through an alkylic linker is reported. The novel 1-(2-(4-arylpiperazin-1-yl)alkyl)-2-(pyridin-3-yl)-1H-benzimidazole derivatives are structurally related to the anti-HIV-1 drug Delavirdine and belong to the bis(heteroaryl)piperazines family (BHAPs), a well known HIV-1 reverse transcriptase inhibitors group. (author)
Directory of Open Access Journals (Sweden)
Longfei Wu
2012-04-01
Full Text Available The title compound, [Cu2(NO32(OH2(C12H8N4O2(H2O2]n, consists of a neutral polymeric CuII complex in which each CuII atom has a distorted octahedral geometry defined by a pyridyl N atom from a 3-(pyridin-3-yl-5-(pyridin-4-yl-1,2,4-oxadiazole ligand and five O atoms from a water molecule, two nitrates and two hydroxides. Two CuII ions are bridged by two hydroxide anions resulting in a Cu2O2 loop, located across an inversion center and connected by the nitrate anions into a broad two-dimensional polymeric structure parallel to (100. In the crystal, there are O—H...O hydrogen bonds between the coodinated water molecule and the nitrate and hydroxide, and between the hydroxide and the nitrate. Intermolecular π–π interactions are present between pyridine rings in adjacent two-dimensional structures, with a centroid–centroid distance of 3.582 (2 Å.
6. Synthesis and crystal structures of 2-methyl-4-aryl-5-oxo-5H-indeno [1,2-b] pyridine carboxylate derivatives
DEFF Research Database (Denmark)
2014-01-01
pyridine derivatives through oxidation. Consequently, the interest in this aromatization reaction, investigation of a wide range of 1, 4-DHPs continues to attract the attention of researchers. Herein, we report the preparation of pyridine derivatives and the crystal structures determined by X......-ray crystallographic methods.Results: The crystal structures and conformational studies of two organic compounds, namely ethyl 2-methyl-4-phenyl-5-oxo-5H-indeno [1,2-b] pyridine-3-carboxylate (I) and ethyl 2-methyl-4-(4 chlorophenyl)-5-oxo-5H-indeno [1,2-b] pyridine-3-carboxylate (II) are reported. The terminal ethyl......) dimer running along 011 direction.Conclusion: The crystal structures ethyl 2-methyl-4-phenyl-5-oxo-5H-indeno [1,2-b] pyridine-3-carboxylate and ethyl 2-methyl-4-(4 chlorophenyl)-5-oxo-5H-indeno [1,2-b] pyridine-3-carboxylate have been investigated in detail. The terminal ethyl group of compound I...
7. Extraction of bivalent vanadium as its pyridine thiocyanate complex and separation from uranium, titanium, chromium and aluminium
International Nuclear Information System (INIS)
Yatirajam, V.; Arya, S.P.
1975-01-01
A simple method is described for the extraction of V(II) as its pyridine thiocyanate complex. Vanadate is reduced to V(II) in 1 to 2 N sulphuric acid by zinc amalgam. Thiocyanate and pyridine are added, the solution is adjusted to pH 5.2 to 5.5 and the complex extracted with chloroform. The vanadium is back-extracted with peroxide solution. Zinc from the reductant accompanies the vanadium but alkali and alkaline earth metal ions, titanium, uranium, chromium and aluminium are separated, besides those ions reduced to the elements by zinc amalgam. The method takes about 20 min and is applicable to microgram as well as milligram amounts of vanadium. (author)
8. Antiinflammatory and neurological activity of pyrithione and related sulfur-containing pyridine N-oxides from Persian shallot (Allium stipitatum)
DEFF Research Database (Denmark)
Krejčová, Petra; Kučerová, Petra; Stafford, Gary Ivan
2014-01-01
ETHNOPHARMACOLOGICAL RELEVANCE: Persian shallot (Allium stipitatum) is a bulbous plant native to Turkey, Iran and Central Asia. It is frequently used in folk medicine for the treatment of a variety of disorders, including inflammation and stress. Antiinflammatory and neurological activities...... of pyrithione and four related sulfur-containing pyridine N-oxides which are prominent constituents of Allium stipitatum were tested. METHODS: The antiinflammatory activity was tested by the ability of the compounds to inhibit cyclooxygenase (COX-1 and COX-2), whereas the neurological activities were evaluated...... by assessing the compounds ability to inhibit monoamine oxidase-A (MAO-A) and acetylcholinesterase (AChE). The compounds׳ affinity for the serotonin transport protein (SERT) and the GABAA-benzodiazepine receptor were also investigated. RESULTS: 2-[(Methylthio)methyldithio]pyridine N-oxide showed very high...
9. Direct Alkynylation of 3H-Imidazo[4,5-b]pyridines Using gem-Dibromoalkenes as Alkynes Source.
Science.gov (United States)
Aziz, Jessy; Baladi, Tom; Piguel, Sandrine
2016-05-20
C2 direct alkynylation of 3H-imidazo[4,5-b]pyridine derivatives is explored for the first time. Stable and readily available 1,1-dibromo-1-alkenes, electrophilic alkyne precursors, are used as coupling partners. The simple reaction conditions include an inexpensive copper catalyst (CuBr·SMe2 or Cu(OAc)2), a phosphine ligand (DPEphos) and a base (LiOtBu) in 1,4-dioxane at 120 °C. This C-H alkynylation method revealed to be compatible with a variety of substitutions on both coupling partners: heteroarenes and gem-dibromoalkenes. This protocol allows the straightforward synthesis of various 2-alkynyl-3H-imidazo[4,5-b]pyridines, a valuable scaffold in drug design.
10. 2,3-Diaminopyridinium 6-carboxypyridine-2-carboxylate
Science.gov (United States)
Foroughian, Mahsa; Foroumadi, Alireza; Notash, Behrouz; Bruno, Giuseppe; Amiri Rudbari, Hadi; Aghabozorg, Hossein
2011-01-01
The asymmetric unit of the title proton-transfer compound, C5H8N3 +·C7H4NO4 −, consists of one mono-deprotonated pyridine-2,6-dicarboxylic acid as anion and one protonated 2,3-diaminopyridine as cation. The crystal packing shows extensive O—H⋯O, N—H⋯O and N—H⋯N hydrogen bonds. Thre are also several π–π interactions between the anions and also between the cations [centriod–centroid distances = 3.6634 (7), 3.7269 (7), 3.6705 (7) and 3.4164 (7) Å]. PMID:22199823
11. 4-Benzyl-6-bromo-2-(4-methoxyphenyl-4H-imidazo[4,5-b]pyridine monohydrate
Directory of Open Access Journals (Sweden)
Y. Ouzidan
2010-04-01
Full Text Available The imidazopyridine fused ring in the title compound, C20H16BrN3O·H2O, is coplanar with the aromatic ring at the 2-position [dihedral angle = 5.2 (1°]. In the five-membered imidazo portion, the C—N bond whose C atom is also connected to the pyridine N atom has predominantly double-bond character [1.334 (2 Å] whereas the C—N bond whose atom is connected to the pyridine C atom has predominantly single-bond character [1.371 (2 Å]. The water molecule engages in hydrogen bonding with the latter N atom; it is also connected to a symmetry-related water molecule, generating a linear chain structure.
12. Synthesis of trifluoromethyl-substituted pyrazolo[4,3-c]pyridines – sequential versus multicomponent reaction approach
Directory of Open Access Journals (Sweden)
Barbara Palka
2014-07-01
Full Text Available A straightforward synthesis of 6-substituted 1-phenyl-3-trifluoromethyl-1H-pyrazolo[4,3-c]pyridines and the corresponding 5-oxides is presented. Hence, microwave-assisted treatment of 5-chloro-1-phenyl-3-trifluoromethylpyrazole-4-carbaldehyde with various terminal alkynes in the presence of tert-butylamine under Sonogashira-type cross-coupling conditions affords the former title compounds in a one-pot multicomponent procedure. Oximes derived from (intermediate 5-alkynyl-1-phenyl-3-trifluoromethyl-1H-pyrazole-4-carbaldehydes were transformed into the corresponding 1H-pyrazolo[4,3-c]pyridine 5-oxides by silver triflate-catalyzed cyclization. Detailed NMR spectroscopic investigations (1H, 13C, 15N and 19F were undertaken with all obtained products.
13. Dynamic changes in nicotinamide pyridine dinucleotide content in normal human epidermal keratinocytes and their effect on retinoic acid biosynthesis
International Nuclear Information System (INIS)
Pinkas-Sarafova, Adriana; Markova, N.G.; Simon, M.
2005-01-01
The function of many enzymes that regulate metabolism and transcription depends critically on the nicotinamide pyridine dinucleotides. To understand the role of NAD(P)(H) in physiology and pathophysiology, it is imperative to estimate both their amount and ratios in a given cell type. In human epidermis and in cultured epidermal keratinocytes, we found that the total dinucleotide content is in the low millimolar range. The dinucleotide pattern changes during proliferation and maturation of keratinocytes in culture. Differences in the concentrations of NAD(P)(H) of 1.5- to 12-fold were observed. This resulted in alteration of the NAD(P)H/NAD(P) ratio, which could impact the differential regulation of both transcriptional and metabolic processes. In support of this notion, we provide evidence that the two-step oxidation of retinol to retinoic acid, a nuclear hormone critical for epidermal homeostasis, can be regulated by the relative physiological amounts of the pyridine dinucleotides
Directory of Open Access Journals (Sweden)
Tushar S. Basu Baul
2013-11-01
Full Text Available The complete binuclear molecule of the title compound, [Cd2I4(C14H12N2O22], is generated by the application of a centre of inversion. The Cd—I bond lengths of the central core are close and uniformly longer than the exocyclic Cd—I bond. The coordination sphere of the CdII atom is completed by two N atoms of a chelating methyl 4-[(pyridin-2-ylmethylideneamino]benzoate ligand, and is based on a square pyramid with the terminal I atom in the apical position. The three-dimensional crystal packing is stabilized by C—H...O and C—H...π interactions, each involving the pyridine ring.
15. N-[5-Methyl-2-(2-nitrophenyl-4-oxo-1,3-thiazolidin-3-yl]pyridine-3-carboxamide monohydrate
Directory of Open Access Journals (Sweden)
Mehmet Akkurt
2011-02-01
Full Text Available In the title compound, C16H14N4O4S·H2O, the benzene and pyridine rings make a dihedral angle of 85.8 (1°. Both enantiomers of the chiral title compound are statistically disordered over the same position in the unit cell. The methyl and carbonyl group attached to the stereogenic center (C5 of the thiazolidine ring were therefore refined with common site-occupation factors of 0.531 (9 and 0.469 (9, respectively, for each stereoisomer. In the crystal, intermolecular N—H...O, O—H...O and O—H...N hydrogen bonds link the molecules, forming a three-dimensional supramolecular network. The crystal structure further shows π–π stacking interactions [centroid–centroid distance = 3.5063 (13 Å] between the pyridine rings.
16. Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF5-substituted phenylboronic esters and iodobenzenes
Czech Academy of Sciences Publication Activity Database
Iakobson, George; Du, J.; Slawin, A. M. Z.; Beier, Petr
2015-01-01
Roč. 11, Aug 26 (2015), s. 1494-1502 ISSN 1860-5397 R&D Projects: GA ČR GAP207/12/0072 Institutional support: RVO:61388963 Keywords : borylation * diazonium salts * iodination * pyridine * sulfur pentafluorides Subject RIV: CC - Organic Chemistry Impact factor: 2.697, year: 2015 http://www.beilstein-journals.org/bjoc/single/articleFullText.htm?publicId=1860-5397-11-162
17. Ultrasound-Promoted One-Pot, Four-Component Synthesis of Pyridin-2(1H-One Derivatives
Directory of Open Access Journals (Sweden)
Jinming Yang
2013-11-01
Full Text Available An efficient one-pot synthesis of 1,6-diamino-2-oxo-1,2,3,4-tetrahydro- pyridine-3,5-dicarbonitrile derivatives by four-component piperidine-catalyzed reactions of a ketone, malononitrile, ethyl cyanoacetate and hydrazine hydrate under ultrasound irradiation is described. This method provides several advantages such as shorter reaction times, excellent yields, and a simple workup procedure.
18. (E-5,6-Dimethoxy-2-(pyridin-4-ylmethylidene-2,3-dihydro-1H-inden-1-one
Directory of Open Access Journals (Sweden)
Mohamed Ashraf Ali
2010-11-01
Full Text Available The molecule of the title compound, C17H15NO3, is slightly twisted, with a dihedral angle of 12.12 (3° between the dihydroindenone group and the pyridine ring. In the crystal, molecules are connected into layers parallel to the ab plane via intermolecular C—H...O hydrogen bonds. Weak π–π [centroid–centroid distance = 3.5680 (6 Å] interactions are also observed.
19. Determination of submicromolar amounts of uranium(VI) by compleximetric titration with pyridine-2,6-dicarboxylic acid
International Nuclear Information System (INIS)
Marsh, S.F.; Betts, M.R.; Rein, J.E.
1980-01-01
Uranium(VI) is selectively determined by a compleximetric titration with pyridine-2,6-dicarboxylic acid, using arsenazo-I indicator and hexamethylenetetramine buffer at pH 4.9. Cyclohexanediaminetetraacetic acid and diethylenetriaminepentaacetic acid provide masking of interfering metal ions. A probe colorimeter apparatus is recommended for end-point detection. The relative standard deviation is 0.6% for 0.17-0.76 μmol of uranium. (Auth.)
20. Determination of submicromolar amounts of uranium(VI) by compleximetric titration with pyridine-2,6-dicarboxylic acid
Energy Technology Data Exchange (ETDEWEB)
Marsh, S F; Betts, M R; Rein, J E [Los Alamos Scientific Lab., NM (USA)
1980-10-01
Uranium(VI) is selectively determined by a compleximetric titration with pyridine-2,6-dicarboxylic acid, using arsenazo-I indicator and hexamethylenetetramine buffer at pH 4.9. Cyclohexanediaminetetraacetic acid and diethylenetriaminepentaacetic acid provide masking of interfering metal ions. A probe colorimeter apparatus is recommended for end-point detection. The relative standard deviation is 0.6% for 0.17-0.76 ..mu..mol of uranium.
1. Synthesis and physicochemical properties of 7,8-dicarba-nido-undecarborane(11) adducts with pyridine bases
International Nuclear Information System (INIS)
Volkov, O.V.; Il'inchik, E.A.; Volkov, V.V.; Voronina, G.S.; Yur'eva, O.P.; Polyanskaya, T.M.
1993-01-01
Synthesis of some 7,8-C 2 B 9 H 11 adducts in conducted via 7.8-C 2 B 9 H 12 ion interaction with iron (3) chloride at presence of pyridine derivatives and their study is carried out using IR, NMR 12 B, PMR, X-ray phase, UV spectroscopy techniques. Character of bond between heterocycle and carborane holyhedron is discussed. Luminescent properties of the prepared compounds under UV radiation are detected
2. Quantum-chemical ab initio and B3LYP study of donor-acceptor complexes of gallium halides with pyridine
International Nuclear Information System (INIS)
Timoshkin, A.Yu.; Suvorov, A.V.; Shefer, G.F.
1999-01-01
By the ab initio and density functional methods the structural characteristics and vibrational spectra of gallium iodide donor-acceptor complexes with pyridine have been calculated. The standard thermodynamic characteristics of GaI 3 Py complex dissociation in gaseous phase have been calculated, as well. Short I-H intramolecular distances suggest that hydrogen iodide elimination with Ga-N chemical bond retention is the first stage of the complex pyrolysis [ru
3. Methyl 2-({6-[(1-methoxy-2-methyl-1-oxopropan-2-ylcarbamoyl]pyridin-2-yl}formamido-2-methylpropanoate
Directory of Open Access Journals (Sweden)
Abdel-Galil E. Amr
2012-05-01
Full Text Available In the title compound, C17H23N3O6, the two methoxycarbonyl C—O—C=O planes are inclined at dihedral angles of 5.3 (4 and 83.9 (4° with respect to the central pyridine ring. An intramolecular N—H...O hydrogen bond generates an S(5 ring motif. In the crystal, molecules are linked into a chain along the c axis via C—H...O hydrogen bonds.
4. Direct detection of pyridine formation by the reaction of CH (CD) with pyrrole: a ring expansion reaction
Energy Technology Data Exchange (ETDEWEB)
Soorkia, Satchin; Taatjes, Craig A.; Osborn, David L.; Selby, Talitha M.; Trevitt, Adam J.; Wilson, Kevin R.; Leone, Stephen R.
2010-03-16
The reaction of the ground state methylidyne radical CH (X2Pi) with pyrrole (C4H5N) has been studied in a slow flow tube reactor using Multiplexed Photoionization Mass Spectrometry coupled to quasi-continuous tunable VUV synchrotron radiation at room temperature (295 K) and 90 oC (363 K), at 4 Torr (533 Pa). Laser photolysis of bromoform (CHBr3) at 248 nm (KrF excimer laser) is used to produce CH radicals that are free to react with pyrrole molecules in the gaseous mixture. A signal at m/z = 79 (C5H5N) is identified as the product of the reaction and resolved from 79Br atoms, and the result is consistent with CH addition to pyrrole followed by Helimination. The Photoionization Efficiency curve unambiguously identifies m/z = 79 as pyridine. With deuterated methylidyne radicals (CD), the product mass peak is shifted by +1 mass unit, consistent with the formation of C5H4DN and identified as deuterated pyridine (dpyridine). Within detection limits, there is no evidence that the addition intermediate complex undergoes hydrogen scrambling. The results are consistent with a reaction mechanism that proceeds via the direct CH (CD) cycloaddition or insertion into the five-member pyrrole ring, giving rise to ring expansion, followed by H atom elimination from the nitrogen atom in the intermediate to form the resonance stabilized pyridine (d-pyridine) molecule. Implications to interstellar chemistry and planetary atmospheres, in particular Titan, as well as in gas-phase combustion processes, are discussed.
5. Spectrophotometric determination of palladium (II) with rubeanic acid (RA) in presence of pyridine, piperidine and 3-picoline
International Nuclear Information System (INIS)
Hassiruzzaman, M.; Hossain, M.A.; Rahman, G.M.M.; Kamal, A.S.M.; Kabir, M.H.; Mustafa, A.I.
1999-01-01
Unpretentious and exclusive methods for the spectrophotometric determination of trace amount of divalent palladium (II) have been developed with rubeanic acid (dithio-oxamide) in presence of secondary ligands like pyridine, piperidine and 3-picoline. Both direct and extraction spectrophotometry showed that coloured rubeanates are only stable in acidic medium. The violent yellow coloured products are formed below ph 5.0 with an absorption maxima at 416.0 and 422.0 (pyridine), 405.0 and 416.5 (piperidine) and 418.0 and 422.0 (3-picoline) both in direct and isoamyl alcohol (IAA) extracted system, respectively. Results indicate that the highest sensitivity and molar absorptivity of Pd-RA pyridine system in direct spectrophotometry were 0.01497 mu g Pd(II) cm/sup -2/ and 7107.89 L mol sup -1/ cm/sup -1/ respectively. IAA extracted Pd-RA-piperidine system was found to give a sensitivity of 0.01087 mu g(Pd(II) cm /sup -2/ and molar absorptivity of 9788.80 L mol /sup -1/ cm/sup -1/ which were the highest of all the system. The effects due to variation of pH, reagent concentrations, order of addition of reagents, time, temperature and solvent media on the absorption spectra have been investigated and the optimum conditions determined. The effects of diverse ions and their tolerance limit have also been studies. (author)
6. Synthesis and structure of pyridine-functionalized mesoporous SBA-15 organosilicas and their application for sorption of diclofenac
Science.gov (United States)
Barczak, Mariusz
2018-02-01
A series of pyridine-functionalized mesoporous silicas have been prepared for the first time via direct co-condensation of tetraethoxysilane (TEOS) and 2-(2-pyridyl)ethyltrimethoxysilane (PETS) using the block copolymer Pluronic P123 as a structure-directing agent. The obtained materials were fully characterized by a wide range of instrumental techniques and employed as adsorbents for the removal of a diclofenac which is considered a priority hazardous drug. The synthesized materials exhibit a high adsorption capacities and rapid adsorption rates. The structural and adsorption properties depend largely on the relative amount of PETS/TEOS ratio: the gradual degradation of ordered structure and porosity was observed with the increasing amount of PETS. However due to the highest loading of pyridine units the most structurally degraded material had the highest adsorption uptake (631 mg g-1) indicating that the surface chemistry plays - along with porosity - an important role in governing the adsorption process. The experimental adsorption data were modelled using the Langmuir, Freundlich and Langmuir-Freundlich isotherms - among them the Langmuir-Freundlich model turned out to be the most suitable for describing adsorption behaviour of diclofenac onto the materials. The collected data show that the pyridine-functionalized mesoporous silicas can be a promising absorbent of pharmaceuticals.
7. Zirconium and Titanium Propylene Polymerization Precatalysts Supported by a Fluxional C 2 -Symmetric Bis(anilide)pyridine Ligand
KAUST Repository
Tonks, Ian A.
2012-03-12
Titanium and zirconium complexes supported by a bis(anilide)pyridine ligand (NNN = pyridine-2,6-bis(N-mesitylanilide)) have been synthesized and crystallographically characterized. C 2-symmetric bis(dimethylamide) complexes were generated from aminolysis of M(NMe 2) 4 with the neutral, diprotonated NNN ligand or by salt metathesis of the dipotassium salt of NNN with M(NMe 2) 2Cl 2. In contrast to the case for previously reported pyridine bis(phenoxide) complexes, the ligand geometry of these complexes appears to be dictated by chelate ring strain rather than metal-ligand π bonding. The crystal structures of the five-coordinate dihalide complexes (NNN)MCl 2 (M = Ti, Zr) display a C 1-symmetric geometry with a stabilizing ipso interaction between the metal and the anilido ligand. Coordination of THF to (NNN)ZrCl 2 generates a six-coordinate C 2-symmetric complex. Facile antipode interconversion of the C 2 complexes, possibly via flat C 2v intermediates, has been investigated by variable-temperature 1H NMR spectroscopy for (NNN)MX 2(THF) n (M = Ti, Zr; X = NMe 2, Cl) and (NNN)Zr(CH 2Ph) 2. These complexes were tested as propylene polymerization precatalysts, with most complexes giving low to moderate activities (10 2-10 4 g/(mol h)) for the formation of stereoirregular polypropylene. © 2012 American Chemical Society.
8. Crystal structures of three co-crystals of 1,2-bis-(pyridin-4-yl)ethane with 4-alk-oxy-benzoic acids: 4-eth-oxy-benzoic acid-1,2-bis-(pyridin-4-yl)ethane (2/1), 4-n-propoxybenzoic acid-1,2-bis(pyridin-4-yl)ethane (2/1) and 4-n-but-oxy-benzoic acid-1,2-bis-(pyridin-4-yl)ethane (2/1).
Science.gov (United States)
Tabuchi, Yohei; Gotoh, Kazuma; Ishida, Hiroyuki
2015-11-01
The crystal structures of three hydrogen-bonded co-crystals of 4-alk-oxy-benzoic acid-1,2-bis-(pyridin-4-yl)ethane (2/1), namely, 2C9H10O3·C12H12N2, (I), 2C10H12O3·C12H12N2, (II), and 2C11H14O3·C12H12N2, (III), have been determined at 93, 290 and 93 K, respectively. In (I), the asymmetric unit consists of one 4-eth-oxy-benzoic acid mol-ecule and one half-mol-ecule of 1,2-bis-(pyridin-4-yl)ethane, which lies on an inversion centre. In (II) and (III), the asymmetric units each comprise two crystallographically independent 4-alk-oxy-benzoic acid mol-ecules and one 1,2-bis-(pyridin-4-yl)ethane mol-ecule. In each crystal, the two components are linked by O-H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1unit of the acid and the base. Similar to the structure of 2:1 unit of (I), the units of (II) and (III) adopt nearly pseudo-inversion symmetry. The 2:1 units of (I), (II) and (III) are linked via C-H⋯O hydrogen bonds, forming tape structures.
9. Synthesis and properties of di- and trinitrobenzyl substituted pyridine derivates. The paper is supposed to be published in the special issue of the ESOR XII 2009 meeting in Haifa. Editor of the issue is Amnon Stanger
OpenAIRE
2010-01-01
Abstract A new method to obtain di- and trinitrobenzyl substituted pyridines is presented. By systematic variation of reaction parameters the reaction conditions were optimized. The novel synthesis circumvents the commonly used nitration of benzyl pyridines, and thus avoids the nitration of the heterocycle which is a common side reaction. Furthermore, the starting materials for the synthesis of a variety of photochromic nitrobenzyl pyridines are easily accessible. The half-lifes of...
10. Poly[tetraaqua-μ3-pyridine-3,5-dicarboxylato-strontium(II
Directory of Open Access Journals (Sweden)
Shirin Daneshvar
2008-02-01
Full Text Available The reaction of strontium(II nitrate with the proton-transfer compound (pdaH2(py-3,5-dc·H2O (where pda = propane-1,3-diamine and py-3,5-dcH2 = pyridine-3,5-dicarboxylic acid leads to the formation of the title polymeric compound, [Sr(C7H3NO4(H2O4]n. The propane-1,3-diaminium cation is not incorporated in this crystal structure. The SrII atom lies on an inversion centre and is eight-coordinated by four O atoms from three py-3,5-dc ligands and four O atoms from four coordinated water molecules. The coordination polyhedron of the SrII atom is a distorted dodecahedron. These binuclear units are connected via the carboxylate O atoms to build a one-dimensional polymeric chain. In the crystal structure, non-covalant interactions consisting of hydrogen bonds (X—H...O, with X = O and C and π–π stacking interactions [3.4604 (19 Å] connect the various components to form a supramolecular structure.
11. Aluminium effects on pyridine nucleotide redox state in roots of Scots pine
Directory of Open Access Journals (Sweden)
Gabriela Lorenc-Plucińska
2014-01-01
Full Text Available After prolonged (3-9 weeks hydroponic treatment of Scots pine seedlings with different concentrations (0.5-4.0 mM of Al (AI(N033, the levels of pyridine nucleotides were determined in root homogenates. After 3 weeks of Al stress, a significant decrease of the anabolic reduction charge (ARC: NADPH/(NADP+ + NADPH and an increase of the redox status (NAD(PH/NAD(P+, catabolic reduction charge (CRC: NADH/(NAD+ + NADH and phosphorylation capacity expressed as NADP+/NAD+ ratio was found in the 4.0 mM Al treatment. After 6 weeks, Al at concentrations of 0.5 and 1.0 mM induced an enhancement of the NADH level and a reduction of NADPH level, but the redox ratios were not changed significantly. After 9 weeks treatment with Al concentrations ranging from 0.5 to 4.0 mM, decreases of the relative level of NADP+, NADPH and NADH and increases of NAD+ were found. Consequently, the CRC, NAD(PH/NAD(P+ and NADP+/NAD+ ratios reached a minimum and ARC a maximum as compared to previous measurements.
12. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex
Energy Technology Data Exchange (ETDEWEB)
Arya, S. P.; Mahajan, M. [Haryana, Kurukshetra Univ. (India). Dept. of Chemistry
1998-05-01
A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 {mu}g ml{sup -1}. Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C. [Italiano] Si propone un rapido e semplice metodo spettrofotometrico per la determinazione dellacido ascorbico. Lacido ascorbico riduce il ferro(III) a ferro(II) che forma con la dimetilgliossima, in presenza di piridina, un complesso colorato in rosso. Lassorbanza della soluzione risultante e misurata a 514 nm e si ottiene una relazione lineare tra assorbanza e concentrazione dellacido ascorbico fino a 14 {mu}g ml{sup -1}. Si sono condotti studi sugli interferenti usualmente associati allacido ascorbico ed e stata valutata lapplicabilita del metodo allanalisi di preparati farmaceutici di vitamina C.
13. Bis{2-[(diisopropylphosphanylamino]pyridine-κ2N1,P}copper(I hexafluoridophosphate
Directory of Open Access Journals (Sweden)
Özgür Öztopcu
2010-07-01
Full Text Available The crystal structure of the title compound, [Cu(C11H19N2P2]PF6, is composed of discrete [Cu(PN-iPr2]+ cations [PN-iPr is 2-(diisopropylphosphanylaminopyridine] and PF6− anions. The Cu(I atom is bis-chelated by two independent PN-iPr ligands. It has a distorted tetrahedral coordination by two P atoms [Cu—P = 2.2277 (4 and 2.2257 (4 Å] and two pyridine N atoms [Cu—N = 2.0763 (11 and 2.0845 (12 Å]. Bond angles about Cu vary from 85.11 (3 (P—Cu—N to 130.37 (2° (P—Cu—P. In the crystal, N—H...F hydrogen bonds link the Cu complexes and the PF6− anions into continuous chains, which show a cross-bedded spatial arrangement. In addition, several weaker C—H...F interactions contribute to the coherence of the structure.
14. Pyridine-substituted thiazolylphenol derivatives: Synthesis, modeling studies, aromatase inhibition, and antiproliferative activity evaluation.
Science.gov (United States)
Ertas, Merve; Sahin, Zafer; Berk, Barkin; Yurttas, Leyla; Biltekin, Sevde N; Demirayak, Seref
2018-04-01
Drugs used in breast cancer treatments target the suppression of estrogen biosynthesis. During this suppression, the main goal is to inhibit the aromatase enzyme that is responsible for the cyclization and structuring of estrogens either with steroid or non-steroidal-type inhibitors. Non-steroidal derivatives generally have a planar aromatic structure attached to the triazole ring system in their structures, which inhibits hydroxylation reactions during aromatization by coordinating the heme group. Bioisosteric replacement of the triazole ring system and development of aromatic/cyclic structures of the side chain can increase the selectivity for aromatase enzyme inhibition. In this study, pyridine-substituted thiazolylphenol derivatives, which are non-steroidal triazole bioisosteres, were synthesized using the Hantzsch method, and physical analysis and structural determination studies were performed. The IC 50 values of the compounds were determined by a fluorescence-based aromatase inhibition assay. Then, their antiproliferative activities on the MCF7 and HEK 293 cell lines were evaluated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Furthermore, the crystal structure of human placental aromatase was subjected to a series of docking experiments to identify the possible interactions between the most active structure and the active site. Lastly, an in silico technique was performed to analyze and predict the drug-likeness, molecular and ADME properties of the synthesized molecules. © 2018 Deutsche Pharmazeutische Gesellschaft.
15. Theoretical study on the molecular tautomerism of the 3-hydroxy-pyridin-4-one system
Science.gov (United States)
2013-04-01
3-hydroxy-pyridin-4-one is a parent molecule for the family of hydroxypyridinones that are known in coordination chemistry as efficient metal ions chelators. In this work, relative stabilities of some possible tautomers were investigated using several quantum chemical methods: CBS (complete basis set methods), Gn, DFT (density functional theory), Hartree-Fock and MP2. Performed calculations show that the system under consideration exists as a mixture of two tautomers with comparable energies. Among them, the hydroxypyridinone structure of the studied molecular system seems to be a bit more stable than the o-dihydroxypyridine one, by a few kJ/mol only. Aromaticity and intra-molecular hydrogen bonding are the main effects influencing the stability of the studied tautomeric structures. Consequently, aromatic effects were calculated using several indices of aromaticity: HOMA (harmonic oscillator model of aromaticity), NICS (nucleus independent chemical shift), H, PDI (para delocalisation index), MCI (multi-centre index) and ASE (aromatic stabilisation energy). The strength of possible intra-molecular hydrogen bonds (H-bonds) was determined by means of the AIM (atoms-in-molecules) method and by calculating enthalpies for theoretical reactions that do or do not involve H-bonds. The AIM method was employed to understand how variations in atomic energies influence the stability of different tautomeric structures.
16. Combined MCD/DFT/TDDFT Study of the Electronic Structure of Axially Pyridine Coordinated Metallocorroles.
Science.gov (United States)
Rhoda, Hannah M; Crandall, Laura A; Geier, G Richard; Ziegler, Christopher J; Nemykin, Victor N
2015-05-18
A series of metallocorroles were investigated by UV-vis and magnetic circular dichroism spectroscopies. The diamagnetic distorted square-pyramidal main-group corrole Ga(tpfc)py (2), the diamagnetic distorted octahedral transition-metal adduct Co(tpfc)(py)2 (3), and paramagnetic distorted octahedral transition-metal complex Fe(tpfc)(py)2 (4) [H3tpfc = tris(perfluorophenyl)corrole] were studied to investigate similarities and differences in the electronic structure and spectroscopy of the closed- and open-shell metallocorroles. Similar to the free-base H3tpfc (1), inspection of the MCD Faraday B-terms for all of the macrocycles presented in this report revealed that a ΔHOMO MCD spectra. In addition, the MCD spectra of the cobalt and the iron complexes were also complicated by a number of charge-transfer states in the visible region. Iron complex 4 also exhibits a low-energy absorption in the NIR region (1023 nm). DFT and TDDFT calculations were used to elaborate the electronic structures and provide band assignments in UV-vis and MCD spectra of the metallocorroles. DFT and TDDFT calculations predict that the orientation of the axial pyridine ligand(s) has a very minor influence on the calculated electronic structures and absorption spectra in the target systems.
17. 3-(Aminocarbonylpyridinium diaqua-bis(pyridine-2,6-dicarboxylatobismuthate(III monohydrate
Directory of Open Access Journals (Sweden)
2012-07-01
Full Text Available The asymmetric unit of the ionic title compound, (C6H7N2O[Bi(C7H3NO42(H2O2]·H2O or (acpyH[Bi(pydc2(H2O2]·H2O, contains an [Bi(pydc2(H2O2]− anion (where pydcH2 is pyridine-2,6-dicarboxylic acid, a protonated 3-(aminocarbonylpyridine as counter-ion, (acpyH+, and one uncoordinated water molecule. The anion is an eight-coordinate complex with a square-antiprismatic geometry around the BiIII atom. In the crystal, extensive O—H...O and N—H...O hydrogen bonds, as well as ion pairing, C=O...π interactions [O...centroid distance = 3.583 (5 Å], π–π stacking [centroid–centroid distance = 3.864 (3 Å], and C—H...π and C—H...O interactions, play an important role in the formation and stabilization of the three-dimensional supramolecular structure.
18. Design, synthesis, and herbicidal activity of novel substituted 3-(pyridin-2-yl)benzenesulfonamide derivatives.
Science.gov (United States)
Xie, Yong; Chi, Hui-Wei; Guan, Ai-Ying; Liu, Chang-Ling; Ma, Hong-Juan; Cui, Dong-Liang
2014-12-31
A series of novel substituted 3-(pyridin-2-yl)benzenesulfonamide derivatives were designed and synthesized using 2-phenylpridines as the lead compound by intermediate derivatization methods in an attempt to obtain novel compound candidates for weed control. The herbicidal activity assay in glasshouse tests showed several compounds (II6, II7, II8, II9, II10, II11, III2, III3, III4, and III5) could efficiently control velvet leaf, youth-and-old age, barnyard grass, and foxtail at the 37.5 g/ha active substance. Especially, the activities of II6, II7, III2, and III4 were proved roughly equivalent to the saflufenacil and better than 95% sulcotrione at the same concentration. The result of the herbicidal activity assay in field tests demonstrated that II7 at 60 g/ha active substance could give the same effect as bentazon at 1440 g/ha active substance to control dayflower and nightshade, meanwhile II7 showed better activity than oxyfluorfen to control arrowhead and security to rice. The present work indicates that II7 may be a novel compound candidate for potential herbicide.
19. Synthesis of some pyridine and pyrimidine derivatives via Michael-Addition
International Nuclear Information System (INIS)
El-Baih, Fatma E.M.; Al-Rasheed, Hessa H.; Al-Hazimi, Hassan M.
2006-01-01
Synthesis of pyridine and pyrimidine analogues 4 and 6-9 were achieved by Michael-addition of compounds containing either active methylene groups like, malononitrile , ethyl cyanoacetate and 1-tetralone or compounds containing active hydrogen atoms like, guanidine in the presence of an oxidizing agent and thiourea to 2-arylmethylidine-1-tetralone and 2-arylmethylidine-6-methoxy-1-tetralone (2) (enones). Addition of malononitrile in piperidine at room temperature to 2-amino-3-cyno-naphtho [1, 2-malonoitrile in sodium alkoxide or sodium hydroxide to 2 gave 4. Cyclization of 3a with acetic anhydride in the presence of conc. H2sO4 gave the naphtha-pyrano[2, 3-d]pyrimidin-8-one (5). Condensation of the pyrimidine thione derivatives 9 with chloroacetic acid gave the 3-oxobenzo[h]thiazoladino[2, 3-b]quinazoline derivatives (10), which were reacted through their active methylene groups with aromatic aldehydes to give the arylidine derivatives 11. These compounds were also prepared in one step by reacting 9 with chloroacetic acid and aromatic aldehydes. Condensation of 9 with 3-bromopropanoic acid gave 4-oxo-benzo[h]1, 3-thiazino[2, 3-b]quinazoline derivatives (12). The structures of the prepared compounds were mainly confirmed on the basis of spectroscopic methods. (author)
20. Calorimetric investigations of hydrogen bonding in binary mixtures containing pyridine and its methyl-substituted derivatives. II. The dilute solutions of methanol and 2-methyl-2-propanol
International Nuclear Information System (INIS)
Marczak, Wojciech; Heintz, Andreas; Bucek, Monika
2004-01-01
Enthalpies of solution of methanol and 2-methyl-2-propanol (tert-butanol) in pyridine and its methyl derivatives were investigated in the range of mole fractions of alcohol x≤0.02 at temperature 298.15 K by a titration calorimeter. Dissolution of methanol is an exothermic process, with heat effects very close to those for water reported in part I of this study. The negative enthalpy of solution increases in the following order: pyridine < 3-methylpyridine < 4-methylpyridine < 2-methylpyridine < 2,6-dimethylpyridine < 2,4,6-trimethylpyridine. Positive enthalpies of solution of 2-methyl-2-propanol increase as follows: 2-methylpyridine < 2,4,6-trimethylpyridine < 4-methylpyridine < 2,6-dimethylpyridine < 3-methylpyridine < pyridine. The propensity of pyridine derivatives to hydrogen bonding is enhanced by the ortho effect. Methyl groups are probably too small to prevent the nitrogen atom in the pyridine ring from hydrogen bonding. However, spacious hydrocarbon group in 2-methyl-2-propanol molecule makes the bonding difficult for 2,6-dimethylpyridine and 2,4,6-trimethylpyridine, thus the number of O-H···N bonds is smaller than that in the solutions of methanol or water. The two latter seem to be very close to each other
1. A combined experimental and computational study of 3-bromo-5-(2,5-difluorophenyl) pyridine and 3,5-bis(naphthalen-1-yl)pyridine: Insight into the synthesis, spectroscopic, single crystal XRD, electronic, nonlinear optical and biological properties
Science.gov (United States)
2018-05-01
Carbon-carbon coupling play a vital role in the synthetic field of organic chemistry. Two novel pyridine derivatives: 3-bromo-5-(2,5-difluorophenyl)pyridine (1) and 3,5-bis(naphthalen-1-yl)pyridine (2) were synthesized via carbon-carbon coupling, characterized by XRD, spectroscopic techniques and also investigated by using density functional theory (DFT). XRD data and optimized DFT studies are found to be in good correspondence with each other. The UV-Vis analysis of compounds under study i.e. (1) and (2) was obtained by using "TD-DFT/B3LYP/6-311 + G(d,p)" level of theory to explain the vertical transitions. Calculated FT-IR and UV-Vis results are found to be in good agreement with experimental FT-IR and UV-Vis findings. Natural bond orbital (NBO) study was performed using B3LYP/6-311 + G(d,p) level to find the most stable molecular structure of the compounds. Frontier molecular orbital (FMO) analysis were performed at B3LYP/6-311 + G(d,p) level of theory, which indicates that the molecules might be bioactive. Moreover, the bioactivity of compounds (1) and (2) have been confirmed by the experimental activity in terms of zones of inhibition against bacteria and fungus. Chemical reactivity of compounds (1) and (2) was indicated by mapping molecular electrostatic potential (MEP) over the entire stabilized geometries of the compounds under study. The nonlinear optical properties were computed with B3LYP/6-311 + G(d,p) level of theory which are found greater than the value of urea due to conjugation effect. Two state model has been further employed to explain the nonlinear optical properties of compounds under investigation.
2. {1-[1-(2-Hydroxyphenylethylidene]-2-(pyridin-2-yl-κNhydrazine-κ2N′,O}{1-[1-(2-oxidophenylethylidene]-2-(pyridin-2-yl-κNhydrazine-κ2N′,O}nickelate(II nitrate hemihydrate
Directory of Open Access Journals (Sweden)
Sarr Mamour
2018-05-01
Full Text Available The 2-hydrazinopyridine precursor has been widely used to prepare ligands of various kinds by condensation with carbonyl compounds. These types of ligands are suitable for synthesizing novel transition metal (II complexes with interesting magnetic properties. In this context we have synthesized the ligand 1-(2-hydroxyphenyl-2-ethylidene-2-(pyridin-2-ylhydrazine (HL which was used in the preparation of the mononuclear title complex, [Ni(C13H12N3O(C13H13N3O]NO3·0.5H2O. As a result of the presence of HL and L in the [{Ni(HL(L}]+ unit, the complex appears to be a supramolecular dimer composed of the Δ(− and Λ(− optical isomers, which are linked by strong hydrogen-bonds. As well as the dimer generated by two mononuclear [{Ni(HL(L}]+ cations, the asymmetric unit also contains two nitrate anions and one water molecule. Each Ni atom is coordinated to two ligand molecules by a nitrogen atom of the pyridine ring, an imine nitrogen atom and a phenolic oxygen atom of one of the ligand molecules and a phenolate oxygen atom of the other organic molecules. The environment around the cation is a distorted octahedron. The basal planes are defined by the two nitrogen atoms of the pyridine rings and the two phenolic oxygen atoms of the ligand, the apical positions being occupied by the azomethine atoms. The O atoms of one of the nitrate ions are disordered over two sets of sites in a 0.745 (9:0.255 (9 ratio. In the crystal, the dimers are linked by numerous hydrogen bonds, forming a three-dimensional framework.
3. Pyridine induction of cytochrome P450IIE1: Evidence for enhanced protein synthesis
International Nuclear Information System (INIS)
Kim, S.G.; Novak, R.F.
1990-01-01
The dose-, and time-dependent induction of P450IIE1 in the rat by pyridine (PY) has been characterized. A single injection of PY (100 mg/kg, i.p.) increased as the levels of IIE1 2-, 3- and 4-fold at 6, 10 and 24 hr, respectively, relative to controls based on p-nitrophenol hydroxylase activity and Western blot analysis. Induction of IIE1 was dose-dependent over the range 10 to 200 mg/kg. Cycloheximide administration completely prevented the induction of IIE1 by PY, while actinomycin D failed to affect PY induction of IIE1. The rate of IIE1 synthesis was examined by labelling of proteins with [ 14 C] leucine in vivo, followed by SDS-PAGE and autoradiographic analysis of isolated microsomes. Enhanced intensity of the IIE1 band was observed in microsomes isolated from rats treated with either PY or acetone relative to untreated rats. Slot and Northern blot analyses were employed to assess IIE1 mRNA levels in total RNA and poly(A + ) mRNA isolated from livers of rats at 1, 5 and 12 hr following a single dose of PY. No increase in IIE1 mRNA in total RNA was monitored. A time-dependent decrease in IIE1 poly(A + ) mRNA however, was observed with the maximal decrease occurring at ∼12 hr. These results suggest that induction of IIE1 by PY does not involve transcriptional activation but occurs by protein synthesis possibly through increased translational efficiency
4. Intermolecular interactions between σ- and π-holes of bromopentafluorobenzene and pyridine: computational and experimental investigations.
Science.gov (United States)
Yang, Fang-Ling; Yang, Xing; Wu, Rui-Zhi; Yan, Chao-Xian; Yang, Fan; Ye, Weichun; Zhang, Liang-Wei; Zhou, Pan-Pan
2018-04-25
The characters of σ- and π-holes of bromopentafluorobenzene (C6F5Br) enable it to interact with an electron-rich atom or group like pyridine which possesses an electron lone-pair N atom and a π ring. Theoretical studies of intermolecular interactions between C6F5Br and C5H5N have been carried out at the M06-2X/aug-cc-pVDZ level without and with the counterpoise method, together with single point calculations at M06-2X/TZVP, wB97-XD/aug-cc-pVDZ and CCSD(T)/aug-cc-pVDZ levels. The σ- and π-holes of C6F5Br exhibiting positive electrostatic potentials make these sites favorably interact with the N atom and the π ring of C5H5N with negative electrostatic potentials, leading to five different dimers connected by a σ-holen bond, a σ-holeπ bond or a π-holeπ bond. Their geometrical structures, characteristics, nature and spectroscopy behaviors were systematically investigated. EDA analyses reveal that the driving forces in these dimers are different. NCI, QTAIM and NBO analyses confirm the existence of intermolecular interactions formed via σ- and π-holes of C6F5Br and the N atom and the π ring of C5H5N. The experimental IR and Raman spectra gave us important information about the formation of molecular complexes between C6F5Br and C5H5N. We expect that the results could provide valuable insights into the investigation of intermolecular interactions involving σ- and π-holes.
5. Butane-1,4-diammonium bis(pyridine-2,6-dicarboxylatocuprate(II trihydrate
Directory of Open Access Journals (Sweden)
2008-05-01
Full Text Available In the title compound, (C4H14N2[Cu(C7H3NO42]·3H2O or (bdaH2[Cu(pydc2]·3H2O (where bda is butane-1,4-diamine and pydcH2 is pyridine-2,6-dicarboxylic acid, the CuII atom is coordinated by four O atoms [Cu—O = 2.0557 (16–2.3194 (16 Å] and two N atoms [Cu—N = 1.9185 (18 and 1.9638 (18 Å] from two chelating rings of the pydc2− anions, which act as tridentate ligands. The geometry of the resulting CuN2O4 coordination can be described as distorted octahedral. The the two pydc2− fragments are almost perpendicular to one another [77.51 (11°]. To balance the charges, two centrosymmetric protonated butane-1,4-diammonium, (bdaH22+ cations are present. In the crystal structure, extensive O—H...O, N—H...O and C—H...O hydrogen bonds [D...A = 2.720 (2–3.446 (3 Å], ion pairing, C—O...π [O...π = 3.099 (2 Å] and π–π stacking interactions between the pydc2− rings [centroid–centroid distance = 3.5334 (15 Å] contribute to the formation of a three-dimensional supramolecular structure.
6. Copolymers based on N-acryloyl-L-leucine and urea methacrylate with pyridine moieties
Directory of Open Access Journals (Sweden)
Buruiana Emil C.
2016-01-01
Full Text Available By using free radical polymerization of (N-methacryloyloxyethyl-N′-4-picolyl-urea (MAcPU and N-acryloyl-L-leucine (AcLeu, an optically active copolymer, poly[(N-methacryloyloxyethyl-N′-4-picolyl-urea-co-N-acryloyl-L-leucine], MAcPU-co-AcLeu (1.86:1 molar ratio was prepared and subsequently functionalized at the pyridine-N with (1R/S-(−/+-10-camphorsulfonic acid (R/S-CSA and at carboxyl group with (R-(+-α-ethylbenzylamine (R-EBA or trans-4-stilbene methanol (t-StM. The structures, chemical composition and chiroptical activity of the monomers and the copolymers were characterized by spectral analysis (FTIR, 1H (13C-NMR, 1H,1H-COSY, UV/vis, thermal methods (TGA, DSC, fluorescence spectroscopy, gel permeation chromatography and specific rotation measurements. Influence of the optical activity of monomer and modifier on modified copolymers suggested a good correlation between the experimental data obtained (23[α]589=+12.5° for AcLeu and MAcPU-co-AcLeu, 23[α]589=0°+27.5° for (MAcPU-co-AcLeu-R/S-CSA, 23[α]589=+25° for (MAcPU-co-AcLeu-R-EBA, and 23[α]589 = 0° for (MAcPU-co-AcLeu-St. In addition, the photobehavior of the stilbene copolymer (MAcPU-co-AcLeu-St in film was investigated by UV-vis spectroscopy. The fluorescence quenching of the stilbene species in the presence of aliphatic/aromatic amine in DMF solution was evaluated, more efficiently being 4,4′−dipyridyl (detection limit: 7.2 x 10-6 mol/L.
7. Novel quinolines carrying pyridine, thienopyridine, isoquinoline, thiazolidine, thiazole and thiophene moieties as potential anticancer agents
Directory of Open Access Journals (Sweden)
Ghorab Mostafa M.
2016-06-01
Full Text Available As a part of ongoing studies in developing new anticancer agents, novel 1,2-dihydropyridine 4, thienopyridine 5, isoquinolines 6–20, acrylamide 21, thiazolidine 22, thiazoles 23–29 and thiophenes 33–35 bearing a biologically active quinoline nucleus were synthesized. The structure of newly synthesized compounds was confirmed on the basis of elemental analyses and spectral data. All the newly synthesized compounds were evaluated for their cytotoxic activity against the breast cancer cell line MCF7. 2,3-Dihydrothiazole-5-carboxamides 27, 25, 4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide (34, 1,2-dihydroisoquinoline-7-carbonitrile (7, 5,6,7,8-tetrahydro-4H-cyclohepta[b]thiophene-3-carboxamide (35, 1,2-dihydroisoquinoline-7-carbonitrile (6, 2-cyano-3-(dimethylamino-N-(quinolin-3-ylacrylamide (21, 1,2-dihydroisoquinoline-7-carbonitriles (11 and (8 exhibited higher activity (IC50 values of 27–45 μmol L–1 compared to doxorubicin (IC50 47.9 μmol L–1. LQ quinolin-3-yl-1,2-dihydroisoquinoline-7-carbonitrile (12, 2-thioxo-2,3-dihydrothiazole-5-carboxamide (28 and quinolin-3-yl-1,2-dihydroisoquinoline-7-carbonitrile (15 show activity comparable to doxorubicin, while (quinolin-3-yl-1,2-dihydroisoquinoline-7-carbonitrile (9, 2,3-dihydrothiazole-5-carboxamide (24, thieno [3,4-c] pyridine-4(5H-one (5, cyclopenta[b]thiophene-3-carboxamide (33 and (quinolin-3-yl-6-stryl-1,2-dihydroisoquinoline-7-carbonitrile (10 exhibited moderate activity, lower than doxorubicin.
8. On the interactions of nitriles and fluoro-substituted pyridines with silicon tetrafluoride: Computations and thin film IR spectroscopy
Science.gov (United States)
Hora, Nicholas J.; Wahl, Benjamin M.; Soares, Camilla; Lara, Skylee A.; Lanska, John R.; Phillips, James A.
2018-04-01
The nature of the interactions between silicon tetrafluoride and series of nitrogen bases, including nitriles (RCN, with R > CH3), pyridine, and various fluoro-substituted pyridines, has been investigated via quantum-chemical computations, low-temperature IR spectroscopy, and bulk reactivity experiments. Using (primarily) M06 with the 6-311+G(2df,2pd) basis set, we obtained equilibrium structures, binding energies, harmonic frequencies, and N-Si potentials in the gas-phase and in bulk dielectric media for an extensive series of 1:1 molecular complexes, including: C6H5CH2CN-SiF4, CH3CH2CN-SiF4, (CH3)3CCN-SiF4, C5H5N-SiF4, 4-FC5H4N-SiF4, 3,5-C5F2H3N-SiF4, 2,6-C5F2H3N-SiF4 and 3,4,5-C5F3H2N-SiF4. In addition, for the analogous 2:1 complexes of pyridine and 3,5-difluororpyridine, we obtained equilibrium structures, binding energies, and harmonic frequencies. The N-Si distances in the 1:1 nitrile complexes are fairly long, ranging from 2.84 Å to 2.88 Å, and the binding energies range from 4.0 to 4.2 kcal/mol (16.7-17.6 kJ/mol). Also, computations predict extremely anharmonic N-Si potentials, for which the inner portions of the curve are preferentially stabilized in dielectric media, which predict an enhancement of these interactions in condensed-phases. However, we see no evidence of bulk reactivity between C6H5CH2CN, CH3CH2CN, or (CH3)3CCN and SiF4, nor any significant interaction between (CH3)3CCN and SiF4 in low temperature IR spectra of solid, (CH3)3CCN/SiF4 thin films. Conversely, the interactions in four of the five 1:1, pyridine-SiF4 complexes are generally stronger; binding energies range from 5.7 to 9.6 kcal/mol (23.8-40.2 kJ/mol), and correspondingly the N-Si distances are relatively short (2.12-2.25 Å). The exception is 2,6-C5F2H3N-SiF4, for which the binding energy is only 3.6 kcal/mol (15.1 kJ/mol), and the N-Si distance is quite long (3.12 Å). In addition, both pyridine and 3,5-difluororpyridine were found to form stable reaction products with SiF4
9. Bactericidal activity of an imidazo[1, 2-a]pyridine using a mouse M. tuberculosis infection model.
Directory of Open Access Journals (Sweden)
Yong Cheng
Full Text Available Tuberculosis remains a global threat due in part to the long treatment regimen and the increased prevalence of drug resistant M. tuberculosis strains. Therefore, new drug regimens are urgently required to combat this deadly disease. We previously synthesized and evaluated a series of new anti-tuberculosis compounds which belong to the family of imidazo[1,2-a]pyridines. This family of compounds showed low nM MIC (minimal inhibitory concentration values against M. tuberculosis in vitro. In this study, a derivative of imidazo[1,2-a]pyridines, (N-(4-(4-chlorophenoxybenzyl-2,7-dimethylimidazo[1,2-a]pyridine-3-carboxamide (ND-09759, was selected as a promising lead compound to determine its protective efficacy using a mouse infection model. Pharmacokinetic analysis of ND-09759 determined that at a dosage of 30 mg/kg mouse body weight (PO gave a maximum serum drug concentration (Cmax of 2.9 µg/ml and a half-life of 20.1 h. M. tuberculosis burden in the lungs and spleens was significantly decreased in mice treated once daily 6 days per week for 4-weeks with ND-09759 compared to untreated mice and this antibiotic activity was equivalent to isoniazid (INH and rifampicin (RMP, two first-line anti-TB drugs. We observed slightly higher efficacy when using a combination of ND-09759 with either INH or RMP. Finally, the histopathological analysis revealed that infected mice treated with ND-09759 had significantly reduced inflammation relative to untreated mice. In conclusion, our findings indicate ND-09759 might be a potent candidate for the treatment of active TB in combination with current standard anti-TB drugs.
10. Syntheses and structures of three heterometallic coordination polymers derived from 4-pyridin-3-yl-benzoic acid
International Nuclear Information System (INIS)
Fang, Wei-Hui; Yang, Guo-Yu
2014-01-01
Three lanthanide–transition-metal coordination polymers, namely, [Er 2 L 6 (H 2 O)][Cu 2 I 2 ] (1), [ErL 3 ][CuI] (2), and [Dy 2 L 6 (BPDC) 0.5 (H 2 O) 4 ][Cu 3 I 2 ] (3) (HL=4-pyridin-3-yl-benzoic acid, H 2 BPDC=4,4′-biphenyldicarboxylic acid) have been made by reacting Ln 2 O 3 and CuI with HL at different temperatures under hydrothermal conditions. All the complexes are characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction, respectively. 1–3 all construct from dimeric (Ln 2 ) and (Cu 2 ) units and exhibit two types of the structural features: 1 is a two-dimensional layer, 2–3 are three-dimensional frameworks. Interestingly, the in situ formation of the BPDC ligand is found in the structure of 3. The distinct architectures of these complexes indicated that the reaction temperature plays an important role in the formation of higher dimensional coordination polymers. - Graphical abstract: By hydrothermal reaction of lanthanide oxide, copper halide, and 4-pyridin-3-yl-benzoic ligand at different temperatures, a series of 1-D to 3-D 3d–4f coordination polymers, namely [ErL 3 (H 2 O) 2 ][CuI], [Er 2 L 6 (H 2 O)][Cu 2 I 2 ], [ErL 3 ][CuI], and [Dy 2 L 6 (BPDC) 0.5 (H 2 O) 4 ][Cu 3 I 2 ], have been made, respectively. - Highlights: • Three novel heterometallic coordination polymers derived from 4-pyridin-3-yl-benzoic acid have been hydrothermally synthesized. • Mixed dinuclear motifs of (Ln 2 ) and (Cu 2 ) serve as secondary building units to generate 2-D layer and 3-D frameworks. • It is proved that higher temperature is apt to permit construction of high dimensional architectures
11. Optoelectronic and Photovoltaic Performances of Pyridine Based Monomer and Polymer Capped ZnO Dye-Sensitized Solar Cells.
Science.gov (United States)
Singh, Satbir; Raj, Tilak; Singh, Amarpal; Kaur, Navneet
2016-06-01
The present research work describes the comparative analysis and performance characteristics of 4-pyridine based monomer and polymer capped ZnO dye-sensitized solar cells. The N, N-dimethyl-N4-((pyridine-4yl)methylene) propaneamine (4,monomer) and polyamine-4-pyridyl Schiff base (5, polymer) dyes were synthesized through one step condensation reaction between 4-pyridinecarboxaldehyde 1 and N, N-dimethylpropylamine 2/polyamine 3. Products obtained N, N-dimethyl-N4-((pyridine-4yl)methylene)propaneamine (4) and polyamine-4-pyridyl Schiff base (5) were purified and characterized using 1H, 13C NMR, mass, IR and CHN spectroscopy. Both the dyes 4 and 5 were further coated over ZnO nanoparticles and characterized using SEM, DLS and XRD analysis. Absorption profile and emission profile was monitored using fluorescence and UV-Vis absorption spectroscopy. A thick layer of these inbuilt dye linked ZnO nanoparticles of dyes (4) and (5) was pasted on one of the conductive side of ITO glass followed with a liquid electrolyte and counter electrode of the same conductive glass. Polyamine-4-pyridyl Schiff base polymer (5) decorated dye sensitized solar cell has shown better exciting photovoltaic properties in the form of short circuit current density (J(sc) = 6.3 mA/cm2), open circuit photo voltage (V(oc) = 0.7 V), fill factor (FF = 0.736) than monomer decorated dye sensitized solar cell. Polymer dye (5) based ZnO solar cell has shown a maximum solar power to electrical conversion efficiency of 3.25%, which is enhanced by 2.16% in case of monomer dye based ZnO solar cell under AM 1.5 sun illuminations.
12. Quantum chemical analysis of the electronic structure and Moessbauer spectra parameters for low spin cyanide- and pyridine-hemichromes
International Nuclear Information System (INIS)
Khleskov, V.I.; Kolpakov, E.V.; Smirnov, A.B.
1992-01-01
The work contains results of quantum-chemical calculations of electronic structure and Moessbauer spectra parameters for low spin S=1/2 hexa-coordinated ferri-porphyrin complexes with cyanide (CN) and pyridine (Py) as axial ligands. Theoretical results made it possible to explain experimentally observed regularity of anomalous quadrupole splitting decrease after substitution of Py-ligands by CN. Comparison of theoretical and experimental data indicated that 2 E g must be the ground state of investigated hemichromes. In this state unpaired electron symmetrically occupies d π -orbitals of Fe-ion. (orig.)
13. The Guareschi Pyridine Scaffold as a Valuable Platform for the Identification of Selective PI3K Inhibitors.
Science.gov (United States)
Galli, Ubaldina; Ciraolo, Elisa; Massarotti, Alberto; Margaria, Jean Piero; Sorba, Giovanni; Hirsch, Emilio; Tron, Gian Cesare
2015-09-18
A novel series of 4-aryl-3-cyano-2-(3-hydroxyphenyl)-6-morpholino-pyridines have been designed as potential phosphatidylinositol-3-kinase (PI3K) inhibitors. The compounds have been synthesized using the Guareschi reaction to prepare the key 4-aryl-3-cyano-2,6-dihydroxypyridine intermediate. A different selectivity according to the nature of the aryl group has been observed. Compound 9b is a selective inhibitor against the PI3Kα isoform, maintaining a good inhibitory activity. Docking studies were also performed in order to rationalize its profile of selectivity.
14. Transformation of Zwitterionic Pyridine Derivatives to a Spiro-Fused Ring System: Azoniabenzo[de]fluorine. Synthesis and Mechanistic Rationalization.
Science.gov (United States)
Palkó, Roberta; Egyed, Orsolya; Rokob, Tibor András; Bombicz, Petra; Riedl, Zsuzsanna; Hajós, György
2015-01-02
Reaction of aryl- and benzylsulfanopyridinium amidates bearing a methyl group in position 6 with 2 equiv of diphenylketene afforded a spiro-fused ring system: azoniabenzo[de]fluorine. By use of an excess amount of ketene, a distinct reaction was observed via which a 1H-pyrrolo[3,2-b]pyridin-2(3H)-one derivative was furnished. The structure of the tetracyclic spiro-fused ring system was unambiguously confirmed by X-ray diffraction, and its formation was rationalized by DFT calculations.
15. Reduction from copper(II) to copper(I) upon collisional activation of (pyridine)2CuCl+
Czech Academy of Sciences Publication Activity Database
Révész, Agnes; Milko, Petr; Žabka, Ján; Schröder, Detlef; Roithová, J.
2010-01-01
Roč. 45, č. 11 (2010), s. 1246-1252 ISSN 1076-5174 R&D Projects: GA AV ČR KJB400550704; GA ČR GA203/08/1487 Grant - others:European Research Council(XE) AdG HORIZOMS Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z40400503 Keywords : copper chloride * electrospray ionization * mass spectrometry * pyridine * redox reactions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.289, year: 2010
16. The Guareschi Pyridine Scaffold as a Valuable Platform for the Identification of Selective PI3K Inhibitors
Directory of Open Access Journals (Sweden)
Ubaldina Galli
2015-09-01
Full Text Available A novel series of 4-aryl-3-cyano-2-(3-hydroxyphenyl-6-morpholino-pyridines have been designed as potential phosphatidylinositol-3-kinase (PI3K inhibitors. The compounds have been synthesized using the Guareschi reaction to prepare the key 4-aryl-3-cyano-2,6-dihydroxypyridine intermediate. A different selectivity according to the nature of the aryl group has been observed. Compound 9b is a selective inhibitor against the PI3Kα isoform, maintaining a good inhibitory activity. Docking studies were also performed in order to rationalize its profile of selectivity.
17. Synthesis, characterization, and photophysical properties of a thiophene-functionalized bis(pyrazolyl) pyridine (BPP) tricarbonyl rhenium(I) complex.
Science.gov (United States)
Lytwak, Lauren A; Stanley, Julie M; Mejía, Michelle L; Holliday, Bradley J
2010-09-07
A bromo tricarbonyl rhenium(I) complex with a thiophene-functionalized bis(pyrazolyl) pyridine ligand (L), ReBr(L)(CO)(3) (1), has been synthesized and characterized by variable temperature and COSY 2-D (1)H NMR spectroscopy, single-crystal X-ray diffraction, and photophysical methods. Complex 1 is highly luminescent in both solution and solid-state, consistent with phosphorescence from an emissive (3)MLCT excited state with an additional contribution from a LC (3)(pi-->pi*) transition. The single-crystal X-ray diffraction structure of the title ligand is also reported.
18. Determination of reaction rate constants for alkylation of 4-(p-nitrobenzyl) pyridine by different alkylating agents.
Science.gov (United States)
Walles, S A
1980-02-01
The rate constants have been determined for the reaction between some different alkylating agents and 4-(p-nitrobenzyl) pyridine (NBP) in methanol. These constants have been compared with those for alkylation of aniline in water. All the constants were lower in methanol than in water but in different degrees. The rate constants of the different alkylating agents have been calculated at a nucleophilic strength n=2. The genetic risk defined as the degree of alkylation of a nucleophile (n=2) is equivalent to the rate constant kn=2 and the target dose. The dependence of the genetic risk on the rate constant (kn=2) is discussed.
19. Helical self-organization and hierarchical self-assembly of an oligoheterocyclic pyridine-pyridazine strand into extended supramolecular fibers.
Science.gov (United States)
Cuccia, Louis A; Ruiz, Eliseo; Lehn, Jean-Marie; Homo, Jean-Claude; Schmutz, Marc
2002-08-02
The synthesis and characterization of an alternating pyridine-pyridazine strand comprising thirteen heterocycles are described. Spontaneous folding into a helical secondary structure is based on a general molecular self-organization process enforced by the conformational information encoded within the primary structure of the molecular strand itself. Conformational control based on heterocyclic "helicity codons" illustrates a strategy for designing folding properties into synthetic oligomers (foldamers). Strong intermolecular interactions of the highly ordered lock-washer subunits of compound 3 results in hierarchical supramolecular self-assembly into protofibrils and fibrils. Compound 3 also forms mechanically stable two-dimensional Langmuir-Blodgett and cast thin films.
20. Ruthenium(II) chloro-bis(bipyridyl) complexes with substituted pyridine ligands: interpretation of their electronic absorption spectra
International Nuclear Information System (INIS)
Sizova, O.V.; Ershov, A.Yu.; Ivanova, N.V.; Shashko, A.D.; Kutejkina-Teplyakova, A.V.
2003-01-01
A number of complexes cis-[Ru(Bipy) 2 (L)(Cl)](BF 4 ), where Bipy-2,2'-bipyridine, L-pyridine, 4-aminopyridine, 4-picoline, nicotinamide, isonicotinamide, 3- and 4-cyanopyridine, 4,4'-bipyridine, trans-1,2-bis(4-pyridyl)ethylene, 4,4'-azopyridine, pyrazine, imidazole and NH 3 , were prepared. Using the CINDO-CI semiempirical method the energies and intensities of transition in electronic absorption spectra (EAS) of the complexes were calculated. It is shown that major differences in EAS of the compounds stem from position of transitions with charge transfer d π (Ru)→π*(L) [ru
1. Gold(III) complexes with 2-substituted pyridines as experimental anticancer agents: solution behavior, reactions with model proteins, antiproliferative properties.
Science.gov (United States)
Maiore, Laura; Cinellu, Maria Agostina; Nobili, Stefania; Landini, Ida; Mini, Enrico; Gabbiani, Chiara; Messori, Luigi
2012-03-01
Gold(III) compounds form a family of promising cytotoxic and potentially anticancer agents that are currently undergoing intense preclinical investigations. Four recently synthesized and characterized gold(III) derivatives of 2-substituted pyridines are evaluated here for their biological and pharmacological behavior. These include two cationic adducts with 2-pyridinyl-oxazolines, [Au(pyox(R))Cl(2)][PF(6)], [pyox(R)=(S)-4-benzyl-2-(pyridin-2-yl)-4,5-dihydrooxazole, I; (S)-4-iso-propyl-2-(pyridin-2-yl)-4,5-dihydrooxazole, II] and two neutral complexes [Au(N,N'OH)Cl(2)], III, and [Au(N,N',O)Cl], IV, containing the deprotonated ligand N-(1-hydroxy-3-iso-propyl-2-yl)pyridine-2-carboxamide, N,N'H,OH, resulting from ring opening of bound pyox(R) ligand of complex II by hydroxide ions. The solution behavior of these compounds was analyzed. These behave as classical prodrugs: activation of the metal center typically takes place through release of the labile chloride ligands while the rest of the molecule is not altered; alternatively, activation may occur through gold(III) reduction. All compounds react eagerly with the model protein cyt c leading to extensive protein metalation. ESI MS experiments revealed details of gold-cyt c interactions and allowed us to establish the nature of protein bound metal containing fragments. The different behavior displayed by I and II compared to III and IV is highlighted. Remarkable cytotoxic properties, against the reference human ovarian carcinoma cell lines A2780/S and A2780/R were disclosed for all tested compounds with IC(50) values ranging from 1.43 to 6.18 μM in the sensitive cell line and from 1.59 to 10.86 μM in the resistant one. The common ability of these compounds to overcome cisplatin resistance is highlighted. The obtained results are thoroughly discussed in the frame of current knowledge on cytotoxic gold compounds. Copyright © 2011 Elsevier Inc. All rights reserved.
2. Cyanoacetanilides intermediates in heterocyclic synthesis. Part 6: Preparation of some hitherto unknown 2-oxopyridine, bipyridine, isoquinoline and chromeno[3,4-c]pyridine containing sulfonamide moiety
Directory of Open Access Journals (Sweden)
Yousry A. Ammar
2014-11-01
Full Text Available Treatment of cyanoacetanilide derivative 1 with tetracyanoethylene (2 in dioxane/triethylamine furnished 2-pyridone derivative 6. Aminopyridine 9 was obtained by cyclization of compound 1 with ketene dithioacetal 7/EtONa. Cyclocondensation of 1 with malononitrile and/or acetylacetone (1:1 M ratio gave pyridine derivatives 11 and 13. Ternary condensation of compound 1, aliphatic aldehydes and malononitrile (1:1:1 M ratio yielded the 2-pyridones 20a and b. Bipyridines 22a–c were prepared by refluxing of compound 21 with active methylene reagents. Cyclization of chromene derivatives 24 and 28 with malononitrile produced the novel chromeno[3,4-c]pyridine 26 and pyrano[3′,2′:6,7]chromeno[3,4-c]pyridine 29.
3. Structure of pyridine and quinoline vinyl ethers according to data from 1H and 13C NMR spectra and quantum-chemical calculations
International Nuclear Information System (INIS)
Afonin, A.V.; Voronov, V.K.; Andriankov, M.A.; Danovich, D.K.
1987-01-01
A systematic investigation of the structure of the vinyl ethers of heterocyclic compounds has not been undertaken. The present work was devoted to investigation of the stereochemical and electronic structure of the vinyl ethers of pyridine and quinoline. The PMR spectra of the samples were recorded for 5% solutions in deuterochloroform on a Tesla BS-497 spectrometer at 100 MHz. The 13 C NMR spectra were recorded on a Tesla BS-567A spectrometer at 25.1 MHz in deuterochloroform with the samples at concentrations of 30%. The internal standard was HMDS. The vinyl ethers of pyridine and quinoline exist preferentially in the nonplanar S-trans conformation. In the vinyl esters of pyridine and quinoline the p-π conjugation is concurrent in nature and depends on the position of the vinyloxy group in the heterocycle
4. The performance of the anthraquinone/p-Si and the pyridine/p-Si rectifying device under X-ray irradiation
International Nuclear Information System (INIS)
Şahin, Yılmaz; Aydoğan, Şakir; Ekinci, Duygu; Turut, Abdulmecit
2016-01-01
Some X-ray irradiation-induced electrical characteristics of the Au/anthraquinone/p-Si and the Au/pyridine/p-Si junction devices have been investigated. The experimental ideality factors increased for both devices with increasing irradiation dose from 25 Gy to 150 Gy. These values ranged from 1.10 to 1.52 for Au/anthraquinone/p-Si and from 1.46 to 1.77 for Au/pyridine/p-Si, respectively. Furthermore, the barrier height of Au/anthraquinone/p-Si increased with increasing irradiation dose from 0.75 to 0.91 eV, whereas it displayed about a constant value for Au/pyridine/p-Si. In addition, the series resistance of both devices increased with x-ray dose too. The increase in the series resistance with x-ray irradiation has been attributed to the decrease in the active dopant densities. It was seen that the ionization damage is effective on most of the junction characteristics. The leakage current of the Au/anthraquinone/p-Si device decreased with x-ray irradiation since the irradiation induced the formation of electron-hole pairs and hydroquinone structure, and thus some of them are trapped by the interface states. The degradation of the I-V curves of Au/pyridine/p-Si/Al device is attributed to the variation of the surface or interface states distribution for the devices. The reverse and forward bias currents relatively increased after x-ray irradiation because of the decrease in bulk lifetime. In addition, ATR-FTIR spectra of anthraquinone and pyridine films showed that pyridine is more stable than anthraquinone under x-ray irradiation. - Highlights: • Two junction devices based on organic materials were fabricated. • The effect of the x-ray irradiation on devices were examined. • Both devices showed x-irradiation-dependence.
5. The performance of the anthraquinone/p-Si and the pyridine/p-Si rectifying device under X-ray irradiation
Energy Technology Data Exchange (ETDEWEB)
Şahin, Yılmaz [Department of Physics, Faculty of Sciences, University of Atatürk, 25240 Erzurum (Turkey); Aydoğan, Şakir, E-mail: [email protected] [Department of Physics, Faculty of Sciences, University of Atatürk, 25240 Erzurum (Turkey); Ekinci, Duygu [Department of Chemistry, Faculty of Sciences, University of Atatürk, 25240 Erzurum (Turkey); Turut, Abdulmecit [Department of Engineering Physics, Faculty of Sciences, Istanbul Medeniyet University (Turkey)
2016-11-01
Some X-ray irradiation-induced electrical characteristics of the Au/anthraquinone/p-Si and the Au/pyridine/p-Si junction devices have been investigated. The experimental ideality factors increased for both devices with increasing irradiation dose from 25 Gy to 150 Gy. These values ranged from 1.10 to 1.52 for Au/anthraquinone/p-Si and from 1.46 to 1.77 for Au/pyridine/p-Si, respectively. Furthermore, the barrier height of Au/anthraquinone/p-Si increased with increasing irradiation dose from 0.75 to 0.91 eV, whereas it displayed about a constant value for Au/pyridine/p-Si. In addition, the series resistance of both devices increased with x-ray dose too. The increase in the series resistance with x-ray irradiation has been attributed to the decrease in the active dopant densities. It was seen that the ionization damage is effective on most of the junction characteristics. The leakage current of the Au/anthraquinone/p-Si device decreased with x-ray irradiation since the irradiation induced the formation of electron-hole pairs and hydroquinone structure, and thus some of them are trapped by the interface states. The degradation of the I-V curves of Au/pyridine/p-Si/Al device is attributed to the variation of the surface or interface states distribution for the devices. The reverse and forward bias currents relatively increased after x-ray irradiation because of the decrease in bulk lifetime. In addition, ATR-FTIR spectra of anthraquinone and pyridine films showed that pyridine is more stable than anthraquinone under x-ray irradiation. - Highlights: • Two junction devices based on organic materials were fabricated. • The effect of the x-ray irradiation on devices were examined. • Both devices showed x-irradiation-dependence.
6. SO 2 Phototriggered Crystalline Nanomechanical Transduction of Aromatic Rotors in Tosylates: Rationalization via Photocrystallography of [Ru(NH 3 ) 4 SO 2 X]tosylate 2 (X = pyridine, 3-Cl-pyridine, 4-Cl-pyridine)
Energy Technology Data Exchange (ETDEWEB)
Sylvester, Sven O.; Cole, Jacqueline M.; Waddell, Paul G.; Nowell, Harriott; Wilson, Claire
2014-07-24
Thermally-reversible solid-state linkage SO2 photoisomers of three complexes in the [Ru(NH3)4SO2X]tosylate2 family are captured in their metastable states using photocrystallography, where X = pyridine (1), 3-Cl-pyridine (2) and 4-Cl-pyridine (3). This photoisomerism only exists in the single-crystal form; accordingly, the nature of the crystalline environment surrounding the photo-active species controls its properties. In particular, the structural role of the tosylate anion needs to be understood against possible chemical influences due to varying the trans ligand, X. The photo-excited geometries, photoconversion levels and thermal stabilities of the photoisomers that form in 1-3 are therefore studied. 1 and 2 yield two photo-isomers at 100 K: the O-bound end-on n1-SO2 Page 1 of 32 ACS Paragon Plus Environment The Journal of Physical Chemistry (MS1) configuration and the side-bound n2-SO2 (MS2), while 3 only exhibits the more thermally stable MS2 geometry. The decay kinetics of the MS2 geometry for 1-3 demonstrate that the greater the free volume of the GS SO2 ligand for a given counterion, the greater the MS2 thermal stability. Furthermore, a rationalization is sought for the SO2 phototriggered molecular rotation of the phenyl ring in the tosylate anion; this is selectively observed in 2, manifesting as nanomechanical molecular transduction. This molecular transduction was not observed in 1, despite the presence of the MS1 geometry due to the close intermolecular interactions between the MS1 SO2 and the neighbouring tosylate ion. The decay of this anionic molecular rotor in 2, however, follows a non-traditional decay pathway, as determined by time-resolved crystallographic analysis; this contrasts with the well-behaved first-order kinetic decay of its MS1 SO2 phototrigger.
7. catena-Poly[[[diaquabis(selenocyanato-κNiron(II]-μ-1,2-bis(pyridin-4-ylethane-κ2N:N′] 1,2-bis(pyridin-4-ylethane disolvate dihydrate
Directory of Open Access Journals (Sweden)
Susanne Wöhlert
2013-06-01
Full Text Available The title compound, {[Fe(NCSe2(C12H12N2(H2O2]·2C12H12N2·2H2O}n, was obtained by the reaction of iron(II sulfate heptahydrate and potassium selenocyanate with 1,2-bis(pyridin-4-ylethane (bpa in water. The FeII cation is coordinated by two N-bonded selenocyanate anions, two water molecules and two 1,2-bis(pyridin-4-ylethane (bpa ligands in a slightly distorted octahedral geometry. In addition, two non-coordinating bpa molecules and two water molecules are present. The FeII cation is located on a center of inversion while the coordinating bpa ligand is located on a twofold rotation axis. The FeII cations are linked by the bpa ligands into chains along the b-axis direction, which are further connected into layers perpedicular to the c axis by O—H...N and O—H...O hydrogen bonds to the non-coordinating bpa and the water molecules. The crystal studied was twinned by pseudo-merohedry (180° rotation along c*; contribution of the minor twin component 3.7%.
8. Effect of alkali metal ions on the pyrrole and pyridine π-electron systems in pyrrole-2-carboxylate and pyridine-2-carboxylate molecules: FT-IR, FT-Raman, NMR and theoretical studies
Science.gov (United States)
Świderski, G.; Wojtulewski, S.; Kalinowska, M.; Świsłocka, R.; Lewandowski, W.
2011-05-01
The FT-IR, FT-Raman and 1H and 13C NMR spectra of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium, rubidium and caesium pyrrole-2-carboxylates were recorded, assigned and compared in the Li → Na → K → Rb → Cs salt series. The effect of alkali metal ions on the electronic system of ligands was discussed. The obtained results were compared with previously reported ones for pyridine-2-carboxylic acid and alkali metal pyridine-2-carboxylates. Calculations for pyrrole-2-carboxylic acid and Li, Na, K pyrrole-2-carboxylates in B3LYP/6-311++G ** level and Møller-Plesset method in MP2/6-311++G ** level were made. Bond lengths, angles and dipole moments as well as aromaticity indices (HOMA, EN, GEO, I 6) for the optimized structures of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium pyrrole-2-carboxylates were also calculated. The degree of perturbation of the aromatic system of ligand under the influence of metals in the Li → Cs series was investigated with the use of statistical methods (linear correlation), calculated aromaticity indices and Mulliken, NBO and ChelpG population analysis method. Additionally, the Bader theory (AIM) was applied to setting the characteristic of the bond critical points what confirmed the influence of alkali metals on the pyrrole ring.
Directory of Open Access Journals (Sweden)
Xiao-Jin Qi
2016-07-01
Full Text Available Three kinds of bridging ligands, 4,4′-oxydibenzoate, 4-(4-carboxyphenoxybenzoate and 3-(pyridin-4-yl-5-(pyridin-3-yl-1H-1,2,4-triazole, link the CdII cations to form the title polymeric complex, [Cd2(C14H8O5(C14H9O52(C12H9N52]n, in which each CdII cation is in a distorted N2O5 pentagonal–bipyramidal coordination geometry. The 4,4′-oxydibenzoate dianion exhibits point group symmetry 2, with the central O atom located on a twofold rotation axis. Classical N—H...O, O—H...N hydrogen bonds and weak C—H...O hydrogen bonds link the complex molecules into a three-dimensional supramolecular architecture. A solvent-accessible void of 53 (2 Å3 is observed, but no solvent molecule could reasonably located there.
10. Pyridinium bis(pyridine-κN)tetrakis(thiocyanato-κN)ferrate(III)–pyrazine-2-carbonitrile–pyridine (1/4/1)
Science.gov (United States)
Shylin, Sergii I.; Gural’skiy, Il’ya A.; Haukka, Matti; Golenya, Irina A.
2013-01-01
In the title compound, (C5H6N)[Fe(NCS)4(C5H5N)2]·4C5H3N3·C5H5N, the FeIII ion is located on an inversion centre and is six-coordinated by four N atoms of the thiocyanate ligands and two pyridine N atoms in a trans arrangement, forming a slightly distorted octahedral geometry. A half-occupied H atom attached to a pyridinium cation forms an N—H⋯N hydrogen bond with a centrosymmetrically-related pyridine unit. Four pyrazine-2-carbonitrile molecules crystallize per complex anion. In the crystal, π–π stacking interactions are present [centroid–centroid distances = 3.6220 (9), 3.6930 (9), 3.5532 (9), 3.5803 (9) and 3.5458 (8) Å]. PMID:23723782
11. Thermodynamics of mixtures containing amines. IX. Application of the concentration-concentration structure factor to the study of binary mixtures containing pyridines
Energy Technology Data Exchange (ETDEWEB)
2009-10-10
Binary mixtures formed by a pyridine base and an alkane, or an aromatic hydrocarbon, or a 1-alkanol have been studied in the framework of the concentration-concentration structure factor, S{sub CC}(0), formalism. Deviations between experimental data and those provided by the DISQUAC model are discussed. Systems containing alkanes are characterized by homocoordination. In pyridine + alkane mixtures, S{sub CC}(0) decreases with the chain length of the longer alkanes, due to size effects. For a given alkane, S{sub CC}(0) also decreases with the number of CH{sub 3}- groups in the pyridine base. This has been interpreted assuming that the number of amine-amine interactions available to be broken upon mixing also decreases similarly, probably as steric hindrances exerted by the methyl groups of the aromatic amine increase with the number of these groups. Homocoordination is higher in mixtures with 3,5-dimethylpyridine than in those with 2,6-dimethylpyridine. That is, steric effects exerted by methyl groups in positions 3 and 5 are stronger than when they are in positions 2 and 6. Similarly, from the application of the DISQUAC (dispersive-quasichemical) model, it is possible to conclude that homocoordination is higher in systems with 3- or 4-methylpyridine than in those involving 2-methylpyridine. Systems including aromatic hydrocarbons are nearly ideal, which seems to indicate that there is no specific interaction in such solutions. Mixtures with 1-alkanols show heterocoordination. This reveals the existence of interactions between unlike molecules, characteristic of alkanol + amine mixtures. Methanol systems show the lowest S{sub CC}(0) values due, partially, to size effects. This explains the observed decrease of homocoordination in such solutions in the order: pyridine > 2-methylpyridine > 2,6-dimethylpyridine. Moreover, as the energies of the OH-N hydrogen bonds are practically independent of the pyridine base considered when mixed with methanol, it suggests that
12. Synthesis, spectroscopic and electrochemical properties of mononuclear and dinuclear bis(bipy)ruthenium(II) complexes containing dimethoxyphenyl(pyridin-2-yl)-1,2,4-triazole ligands
NARCIS (Netherlands)
Passaniti, Paolo; Browne, Wesley R.; Lynch, Fiona C.; Hughes, Donal; Nieuwenhuyzen, Mark; James, Paraic; Maestri, Mauro; Vos, Johannes G.
2002-01-01
The ligands HL1 and H(2)L2 and the complexes [Ru(bipy)(2)L1]PF6.2H(2)O 1, [(Ru(bipy)(2))(2)L2](PF6)(2).7H(2)O 2, {where HL1 = 3-(2', 5'-dimethoxyphenyl)-5-(pyridin-2"-yl)- 1H-1,2,4-triazole, H(2)L2 = 1,4- bis(5'-(pyridin-2"-yl)- 1'H- 1', 2', 4'-triazol-3'-yl)- 2,5-dimethoxybenzene and bipy =
13. (Pyridine)(tetrahydroborato)zinc complex, (Zn(BH4)2(py)), as a new stable, efficient and chemoselective reducing agent for reduction of carbonyl compounds
International Nuclear Information System (INIS)
2003-01-01
(Pyridine)(tetrahydroborato)zinc complex, (Zn(BH 4 ) 2 (py)), as a stable white solid, was prepared quantitatively by complexation of an equimolar amount of zinc tetrahydroborate and pyridine at room temperature. This reagent can easily reduce variety of carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and α,β-unsaturated carbonyl compounds to their corresponding alcohols in good to excellent yields. Reduction reactions were performed in ether or THF at room temperature or under reflux conditions. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing agent
14. (Pyridine)(tetrahydroborato)zinc complex, (Zn(BH{sub 4}){sub 2}(py)), as a new stable, efficient and chemoselective reducing agent for reduction of carbonyl compounds
Energy Technology Data Exchange (ETDEWEB)
2003-04-01
(Pyridine)(tetrahydroborato)zinc complex, (Zn(BH{sub 4}){sub 2}(py)), as a stable white solid, was prepared quantitatively by complexation of an equimolar amount of zinc tetrahydroborate and pyridine at room temperature. This reagent can easily reduce variety of carbonyl compounds such as aldehydes, ketones, acyloins, {alpha}-diketones and {alpha},{beta}-unsaturated carbonyl compounds to their corresponding alcohols in good to excellent yields. Reduction reactions were performed in ether or THF at room temperature or under reflux conditions. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing agent.
15. Synthesis and antitumor activity of some novel thiophene, pyrimidine, coumarin, pyrazole and pyridine derivatives
Directory of Open Access Journals (Sweden)
Albratty Mohammed
2017-03-01
Full Text Available 2-Cyano-N-(thiazol-2-yl acetamide (2a and 2-cyano-N-(oxazol- 2-yl acetamide (2b were obtained via the reaction of ethyl cyanoacetate with either 2-aminothiazole (1a or 2-aminooxazole (1b. The formed products were directed toward the reaction with cyclopentanone and elemental sulfur in the presence of triethylamine to give cyclopenta[b]thiophene derivatives (3a,b. The latter products were reacted with either ethyl cyanoacetate or malononitrile to form compounds 4a,b and 5a,b, respectively. Compounds 4a,b were aimed at synthesizing some heterocyclic compounds; thus internal cyclization reactions were introduced to form compounds 6a,b. Also, compounds 4a,b reacted with salicylaldehyde, hydrazine derivatives and either urea or thiourea to produce coumarin derivatives (7a,b, pyrazole derivatives (8a-d and pyrimidine derivatives (9a-d, respectively. Reaction of either benzaldehyde or benzene diazonium chloride (11 with compounds 4a,b afforded compounds 10a,b and 12a,b, respectively. On the other hand, compounds 5a,b underwent internal cyclization to form pyrimidine derivatives 13a,b. Also, when compounds 5a,b reacted with either ethyl cyanoacetate or malononitrile, they gave pyridine derivatives (15a-d through the formation of intermediates (14a-d. Finally, formation of fused pyrimidine derivatives (17a,b was achieved through the reaction of compounds 5a,b and salicylaldehyde applying two different pathways. The first pathway used a catalytic amount of piperidine to form compounds 16a,b; the latter products underwent cyclization to give compounds 17a,b. The second pathway, using a catalytic amount of sodium ethoxide solution directly in one step, afforded compounds 17a,b. Structures of the newly synthesized compounds were established using IR, 1H NMR, 13C NMR and mass spectrometry and their antitumor activity was investigated. Some of these compounds showed promising inhibitory effects on three different cell lines. However, fused pyrimidine
16. Xafs studies on actinide-pyridine-diamide complexes for development of an innovative separation process
International Nuclear Information System (INIS)
Hideaki, Shiwaku; Tsuyoshi, Yaita; Tohru, Kobayashi; Masahiko, Numakura; Tsuyoshi, Yaita; Shinichi, Suzuki; Yoshihiro, Okamoto
2007-01-01
We have been studying the bond properties and the structures of actinide (An) and lanthanide (Ln) complexes in detail using several kinds of X-ray analyses by synchrotron radiation in order to elucidate the ionic recognition mechanism of organic ligands. Generally, an oxygen donor type ligand separates both An and Ln from solutions of spent fuel or high level radioactive waste. Separation ability of this type of ligand for An and Ln follows the order of the surface charge density of an ion, i.e., An 4+ > AnO 2 2+ > An 3+ = Ln 3+ > AnO 2+ and/or a few structural factors. Therefore, this type of ligand is ineffective for the separation of An 3+ and Ln 3+ due to their similar chemical properties. Recently, new extractants like aromatic N-donor ligands have been developed using the preference of soft-donors to achieve the An 3+ /Ln 3+ separation. However, aromatic N-donor ligands often show a few problems such as protonation. In this developing process, we synthesized a new type of ligand, N,N'-dimethyl-N,N'-diphenyl-pyridine-2,6-carboxy-amide (DMDPh-PDA). The PDA is hybrid type ligand having oxygen and nitrogen as donor atoms and follows a unique separation order, i.e., An 4+ > An 3+ > AnO 2 2+ > Ln 3+ > AnO 2 + , probably arising from the combined effects of covalent bonding and steric hindrance. Hence, clarification of any ionic recognition mechanism of the PDA is very interesting from the view point of structural analysis. In this presentation, we will show XAFS results of An and Ln complexes with PDA in solution and discuss separation mechanism of An and Ln by PDA. Various kinds of complexes between Ln/An and PDA were prepared for XAFS analysis. The Ln complexes were measured in transmission mode at the K absorption edge on the BL11XU at SPring-8. On the other hand, the U complexes were measured in fluorescence mode at the L III absorption edge on the BL-27B at Photon Factory, High-energy Accelerator Research Organization (KEK). (authors)
17. Theoretical Investigation on Single-Wall Carbon Nanotubes Doped with Nitrogen, Pyridine-Like Nitrogen Defects, and Transition Metal Atoms
Directory of Open Access Journals (Sweden)
Michael Mananghaya
2012-01-01
Full Text Available This study addresses the inherent difficulty in synthesizing single-walled carbon nanotubes (SWCNTs with uniform chirality and well-defined electronic properties through the introduction of dopants, topological defects, and intercalation of metals. Depending on the desired application, one can modify the electronic and magnetic properties of SWCNTs through an appropriate introduction of imperfections. This scheme broadens the application areas of SWCNTs. Under this motivation, we present our ongoing investigations of the following models: (i (10, 0 and (5, 5 SWCNT doped with nitrogen (CNxNT, (ii (10, 0 and (5, 5 SWCNT with pyridine-like defects (3NV-CNxNT, (iii (10, 0 SWCNT with porphyrine-like defects (4ND-CNxNT. Models (ii and (iii were chemically functionalized with 14 transition metals (TMs: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Pt and Au. Using the spin-unrestricted density functional theory (DFT, stable configurations, deformations, formation and binding energies, the effects of the doping concentration of nitrogen, pyridine-like and porphyrine-like defects on the electronic properties were all examined. Results reveal that the electronic properties of SWCNTs show strong dependence on the concentration and configuration of nitrogen impurities, its defects, and the TMs adsorbed.
18. Crucial role of molecular planarity on the second order nonlinear optical property of pyridine based chalcone single crystals
Science.gov (United States)
Menezes, Anthoni Praveen; Jayarama, A.; Ng, Seik Weng
2015-05-01
An efficient nonlinear optical material 2E-3-(4-bromophenyl)-1-(pyridin-3-yl) prop-2-en-1-one (BPP) was synthesized and single crystals were grown using slow evaporation solution growth technique at room temperature. Grown crystal had prismatic morphology and its structure was confirmed by various spectroscopic studies, elemental analysis, and single crystal X-ray diffraction (XRD) technique. The single crystal XRD of the crystal showed that BPP crystallizes in monoclinic system with noncentrosymmetric space group P21 and the cell parameters are a = 5.6428(7) Å, b = 3.8637(6) Å, c = 26.411(2) Å, β = 97.568(11) deg and v = 575.82(12) Å3. The UV-Visible spectrum reveals that the crystal is optically transparent and has high optical energy band gap of 3.1 eV. The powder second harmonic generation efficiency (SHG) of BPP is 6.8 times that of KDP. From thermal analysis it is found that the crystal melts at 139 °C and decomposes at 264 °C. High optical transparency down to blue region, higher powder SHG efficiency and better thermal stability than that of urea makes this chalcone derivative a promising candidate for SHG applications. Furthermore, effect of molecular planarity on SHG efficiency and role of pyridine ring adjacent to carbonyl group in forming noncentrosymmetric crystal systems of chalcone family is also discussed.
19. Proof of concept for molecular velcro based on the attractive interaction between porphyrin and pyridine containing copolymers
Directory of Open Access Journals (Sweden)
M. Sievers
2018-06-01
Full Text Available In this short communication, we investigated the synthesis and mixing of porphyrin and pyridine functionalized copolymers as a proof of concept for a velcro-like interaction. A functionalized porphyrin monomer with one polymerizable side chain was synthesized following a rational synthetic pathway. Subsequent copolymerization and careful removal of residual free porphyrin led to poly(n-butyl acrylate-co-5,10,15-triphenyl-20-(3-vinylphenylporphyrin. The immobilized porphyrin was transformed into the corresponding zinc(II complex, which is capable of the coordinative binding of one pyridine moiety. Complete metallation was proven by absorption spectroscopy. 4-Vinylpyridine was immobilized by copolymerization with n-butyl acrylate, too. Via controlled radical polymerization conditions, the molecular weight of poly(n-butyl acrylate-co-4-vinylpyridine was limited to one tenth of the molecular weight of the porphyrin containing copolymer. This large difference in the molecular weight easily allowed identifying the polymers in the mixture of both. With the help of diffusion ordered nuclear magnetic resonance spectroscopy, the complete and temperature-stable precipitation of the porphyrin containing copolymer was observed, proving the expected attractive interaction and supramolecular network formation.
20. Low-energy electron-induced dissociation in gas-phase nicotine, pyridine, and methyl-pyrrolidine
Science.gov (United States)
Ryszka, Michal; Alizadeh, Elahe; Li, Zhou; Ptasińska, Sylwia
2017-09-01
Dissociative electron attachment to nicotine, pyridine, and N-methyl-pyrrolidine was studied in the gas phase in order to assess their stability with respect to low-energy electron interactions. Anion yield curves for different products at electron energies ranging from zero to 15 eV were measured, and the molecular fragmentation pathways were proposed. Nicotine does not form a stable parent anion or a dehydrogenated anion, contrary to other biological systems. However, we have observed complex dissociation pathways involving fragmentation at the pyrrolidine side accompanied by isomerization mechanisms. Combining structure optimization and enthalpy calculations, performed with the Gaussian09 package, with the comparison with a deuterium-labeled N-methyl-d3-pyrrolidine allowed for the determination of the fragmentation pathways. In contrast to nicotine and N-methylpyrrolidine, the dominant pathway in dissociative electron attachment to pyridine is the loss of hydrogen, leading to the formation of an [M—H]- anion. The presented results provide important new information about the stability of nicotine and its constituent parts and contribute to a better understanding of the fragmentation mechanisms and their effects on the biological environment.
1. Multi-signalling cation sensing behaviour of a bis(pyridin-2-yl methyl)aniline based hetarylazo dye
International Nuclear Information System (INIS)
Kaur, Paramjit; Sareen, Divya; Kaur, Mandeep; Singh, Kamaljit
2013-01-01
Graphical abstract: The chromogenic and electrochemical behaviour of bis(pyridine-2-yl methyl)aniline based hetarylazo dye gets perturbed in the presence of cations, most effective being Cu 2+ . The conversion of ICT to ICT/MLCT is witnessed by TD-DFT calculations. -- Highlights: •Cation sensing of hetarylazo dye based upon visual, absorption and electrochemical changes is described. •Sensing mechanism is based upon perturbation in intramolecular charge-transfer upon interaction with cations. •Sensing protocol is supported by 1 H NMR studies as well as theoretical calculations. •Hetarylazo dye acts as a multichannel sensor. •Response of the dye towards various cations has also been explored in acidic pH window. -- Abstract: We investigated the cation sensing behaviour of a bis(pyridin-2-yl methyl)aniline appended hetarylazo dye via chromogenic and electrochemical transduction channels. The binding pocket constituting both the pyridyl as well as aniline nitrogen atoms acts as recognition site for the cations and consequent perturbation in the intramolecular charge-transfer prevailing in the dye results in the chromogenic response manifested in the form of hypsochromic shift in the intramolecular charge-transfer band and the attendant naked-eye color changes. The dye exhibits significant changes in its electrochemical behaviour in the presence of cations. The experimental results are also rationalized by time-dependent density functional theory (TD-DFT) calculations
2. Synthesis and characterisation of 5-acyl-6,7-dihydrothieno[3,2-c]pyridine inhibitors of Hedgehog acyltransferase
Directory of Open Access Journals (Sweden)
Thomas Lanyon-Hogg
2016-06-01
Full Text Available In this data article we describe synthetic and characterisation data for four members of the 5-acyl-6,7-dihydrothieno[3,2-c]pyridine (termed “RU-SKI” class of inhibitors of Hedgehog acyltransferase, including associated NMR spectra for final compounds. RU-SKI compounds were selected for synthesis based on their published high potencies against the enzyme target. RU-SKI 41 (9a, RU-SKI 43 (9b, RU-SKI 101 (9c, and RU-SKI 201 (9d were profiled for activity in the related article “Click chemistry armed enzyme linked immunosorbent assay to measure palmitoylation by Hedgehog acyltransferase” (Lanyon-Hogg et al., 2015 [1]. 1H NMR spectral data indicate different amide conformational ratios between the RU-SKI inhibitors, as has been observed in other 5-acyl-6,7-dihydrothieno[3,2-c]pyridines. The synthetic and characterisation data supplied in the current article provide validated access to the class of RU-SKI inhibitors.
3. Am and Eu extraction from acidic media by synergistic mixtures of substituted bis-tetrazolyl pyridines with chlorinated cobalt dicarbollide
International Nuclear Information System (INIS)
Smirnov, I.V.; Chirkov, A.V.; Babain, V.A.; Pokrovskaya, E.Yu.; Artamonova, T.A.
2009-01-01
Americium (Am) and europium (Eu) extraction from HNO 3 and HClO 4 media by a synergistic mixture of 2.6-bis(1-aryl-1H-tetrazol-5-yl)pyridines (ATP) with chlorinated cobalt dicarbollide (CCD) was studied by using m-nitrobenzotrifluoride, phenyltrifluoromethyl sulfone, and 1,2-dichloroethane as diluents. We examined the effects of diluents, of the aqueous phase composition and the nature of substituents in the ATP aryl ring on Am/Eu extraction efficiency and selectivity. The Am/Eu separation factor was found to be close to 100 at the optimal ratio of ATPs: CCD ∝ 1:1. We also studied the extraction of 85 Sr, 137 Cs and 133 Ba; a PhATP-CCD mixture provided the separation of the Sr/Ba pair with a factor of 35. A high resistance of 2,6-bis-aryltetrazolyl pyridines to 6 M nitric and perchloric acids at 95 C was demonstrated. (orig.)
4. A density functional study of inhibition of the HDS hydrogenation pathway by pyridine, benzene, and H2S on MoS2-based catalysts
DEFF Research Database (Denmark)
Logadottir, A.; Moses, Poul Georg; Hinnemann, Berit
2006-01-01
hydrogen from neighboring SH group can he transferred to the pyridine molecule resulting in the creation of more strongly held pyridinium ions. At the so-called S edge, hydrogen is tightly bound and this transfer is not favored. The present results, therefore, also stress the importance of the hydrogen...... binding properties of HDS catalysts. (c) 2005 Elsevier B.V. All rights reserved....
5. Reactions of zinc hydride and magnesium hydride with pyridine; synthesis and characterization of 1,4-dihydro-1-pyridylzinc and -magnesium complexes
NARCIS (Netherlands)
Koning, A.J. de; Boersma, J.; Kerk, G.J.M. van der
1980-01-01
The synthesis and characterization of 1,4-dihydro-1-pyridylzinc and -magnesium complexes are described. Zinc hydride and magnesium hydride dissolve in and react with pyridine, and the reaction has been studied in detail in the case of zinc hydride. Evaporation of the solvent after 1–2 hours at 0°C
6. Syntheses of two potential dopamine D{sub 4} receptor radioligands: {sup 18}F labelled chromeno[3,4-c]pyridin-5-ones
Energy Technology Data Exchange (ETDEWEB)
Gu-Cai Li; Duan-Zhi Yin; Ming-Wei Wang; Deng-Feng Cheng; Yong-Xian Wang [Research Center of Radiopharmaceuticals, Shanghai Inst. of Applied Physics, Chinese Academy of Sciences, Shanghai, SH (China)
2006-07-01
The dopamine D{sub 4} receptor is hypothesized to relate with the pathophysiology and pharmacotherapy of schizophrenia while its level in brain regions is much lower and to date no suitable tracer is available for the study of D{sub 4} receptor in vivo. Therefore, selective imaging agents for the D{sub 4} subtype are badly needed. Based on the structure-activity analysis of chromeno[3,4-c]pyridin-5-ones as dopamine D{sub 4} receptor ligands, two fluorine-18 labelled chromeno[3,4-c] pyridin-5-one derivatives, 3-(4-[{sup 18}F]fluorobenzyl)-8-hydroxy-1,2,3,4-tetrahydrochromeno[3,4-c]pyridin-5-one and 3-(4-[{sup 18}F]fluorobenzyl)-8,9-dimethoxy-1,2,3,4-tetrahydrochromeno[3,4-c]pyridin-5-one were synthesized through a two-step one-pot method. Their radiochemical yields were around 19.7% (decay-corrected) and radiochemical purities were higher than 95% with specific activities of about 120 GBq/{mu}mol. (orig.)
7. Synthesis of substituted [{sup 123}I]imidazo[1,2-a]pyridines as potential probes for the study of the peripheral benzodiazepine receptors using SPECT
Energy Technology Data Exchange (ETDEWEB)
Katsifis, A.; Mattner, F.; Dikic, B.; Papazian, V. [Radiopharmaceuticals Div. R and D, ANSTO, Menai, NSW (Australia)
2000-07-01
The imidazo[1,2-a]pyridines N,N'-dimethyl-6-chloro-(4'-iodophenyl)imidazo[1,2-a]pyridine-3-acetamide 1. N,N'-diethyl-6-chloro-(4'-iodophenyl)imidazo[1,2-a]pyridine-3-acetamide 2, and N-methyl-6-chloro-(4'-iodophenyl)imidazo[1,2-a]pyridine-3-acetamide 3, are high affinity and selective ligands for the peripheral benzodiazepineodiazepine receptors (PBR). The [{sup 123}I]1-3 labelled analogues of these compounds were subsequently synthesised for the potential study of the PBR in vivo using SPECT. Radioiodination was achieved by iododestannylation reactions of the corresponding tributyl tin precursors with Na[{sup 123}I] in the presence of peracetic acid, chloramine-T or Iodogen. Purification of the crude product was achieved by semipreparative C-18 RP HPLC to give the products in radiochemical yields of 40-85%. The products were obtained in >97% chemical and radiochemical purity and with specific activities >80 GBq/{mu}mol. (orig.)
8. Synthesis of substituted [123I]imidazo[1,2-a]pyridines as potential probes for the study of the peripheral benzodiazepine receptors using SPECT
International Nuclear Information System (INIS)
Katsifis, A.; Mattner, F.; Dikic, B.; Papazian, V.
2000-01-01
The imidazo[1,2-a]pyridines N,N'-dimethyl-6-chloro-(4'-iodophenyl)imidazo[1,2-a]pyridine-3-acetamide 1. N,N'-diethyl-6-chloro-(4'-iodophenyl)imidazo[1,2-a]pyridine-3-acetamide 2, and N-methyl-6-chloro-(4'-iodophenyl)imidazo[1,2-a]pyridine-3-acetamide 3, are high affinity and selective ligands for the peripheral benzodiazepineodiazepine receptors (PBR). The [ 123 I]1-3 labelled analogues of these compounds were subsequently synthesised for the potential study of the PBR in vivo using SPECT. Radioiodination was achieved by iododestannylation reactions of the corresponding tributyl tin precursors with Na[ 123 I] in the presence of peracetic acid, chloramine-T or Iodogen. Purification of the crude product was achieved by semipreparative C-18 RP HPLC to give the products in radiochemical yields of 40-85%. The products were obtained in >97% chemical and radiochemical purity and with specific activities >80 GBq/μmol. (orig.)
9. Facilitating Students' Review of the Chemistry of Nitrogen-Containing Heterocyclic Compounds and Their Characterization through Multistep Synthesis of Thieno[2,3-"b"]Pyridine Derivatives
Science.gov (United States)
Liu, Hanlin; Zaplishnyy, Vladimir; Mikhaylichenko, Lana
2016-01-01
A multistep synthesis of thieno[2,3-"b"]pyridine derivatives is described that is suitable for the upper-level undergraduate organic laboratory. This experiment exposes students to various hands-on experimental techniques as well as methods of product characterization such as IR and [superscript 1]H NMR spectroscopy, and…
10. Morphological changes of monolayers of two polymerizable pyridine amphiphiles upon complexation with Cu(II) ions at the air-water interface
NARCIS (Netherlands)
Werkman, P.J.; Schouten, A.J.; Noordegraaf, M.A.; Kimkes, P.; Sudhölter, E.J.R.
1998-01-01
The monolayer behavior of two amphiphilic, diacetylenic units containing pyridine Ligands at the air-water interface is studied by measuring the surface pressure-area isotherms and by Brewster angle microscopy(BAM). Both amphiphiles form stable monolayers at the air-water interface. The amphiphile
11. Synthesis and muscarinic receptor pharmacology of a series of 4,5,6,7-tetrahydroisothiazolo[4,5-c]pyridine bioisosteres of arecoline
DEFF Research Database (Denmark)
Pedersen, H; Bräuner-Osborne, H; Ball, R G
1999-01-01
A series of O- and ring-alkylated derivatives of 4,5,6,7-tetrahydroisothiazolo[4,5-c]pyridin-3-ol was synthesized via treatment of appropriately substituted 4-benzylamino-1,2,5,6-tetrahydropyridine-3-carboxamides with hydrogen sulfide and subsequent ring closure by oxidation with bromine. The mus...
12. Pyridine synthesis by reactions of allyl amines and alkynes proceeding through a Cu(OAc)2 oxidation and Rh(III)-catalyzed N-annulation sequence.
Science.gov (United States)
Kim, Dong-Su; Park, Jung-Woo; Jun, Chul-Ho
2012-11-28
A new methodology has been developed for the synthesis of pyridines from allyl amines and alkynes, which involves sequential Cu(II)-promoted dehydrogenation of the allylamine and Rh(III)-catalyzed N-annulation of the resulting α,β-unsaturated imine and alkyne.
13. Pure white OLED based on an organic small molecule: 2,6-Di(1H-benzo[d]imidazol-2-yl)pyridine
Science.gov (United States)
Liu, Jian
2015-10-01
2,6-Di(1H-benzo[d]imidazol-2-yl)pyridine (DBIP) was synthesized. The single-crystal structure of DBIP was resolved. DBIP-based OLED was fabricated. The electroluminescence for the device corresponds to a pure white emission. In addition, thermal stability, UV-vis, photoluminescence and electrochemical behaviors of DBIP were investigated as well.
14. Schiff Bases of Benzothiazol-2-ylamine and Thiazolo[5,4-b] pyridin-2-ylamine as Anticonvulsants: Synthesis, Characterization and Toxicity Profiling.
Science.gov (United States)
Shukla, Rashmi; Singh, Ajeet P; Sonar, Pankaj K; Mishra, Mudita; Saraf, Shailendra K
2016-01-01
Schiff bases have a broad spectrum of biological activities like antiinflammatory, analgesic, antimicrobial, anticonvulsant, antitubercular, anticancer, antioxidant, anthelmintic and so forth. Thus, after a thorough perusal of literature, it was decided to conjugate benzothiazol-2-ylamine/thiazolo [5, 4-b] pyridin-2-ylamine with aromatic and heteroaromatic aldehydes to get a series of Schiff bases. Synthesis, characterization, in-silico toxicity profiling and anticonvulsant activity of the Schiff bases of Benzothiazol-2-ylamine and Thiazolo [5, 4-b] pyridin-2-ylamine. Aniline/4-aminopyridine was converted to the corresponding thiourea derivatives, which were cyclized to obtain benzothiazol-2-ylamine/thiazolo [5, 4-b] pyridin-2-ylamine. Finally, these were condensed with various aromatic and heteroaromatic aldehydes to obtain Schiff bases of benzothiazol-2-ylamine and thiazolo [5, 4-b] pyridin-2-ylamine. The synthesized compounds were characterized and screened for their anticonvulsant activity using maximal electroshock (MES) test and isoniazid (INH) induced convulsions test. In-silico toxicity profiling of all the synthesized compounds was done through "Lazar" and "Osiris" properties explorer. Majority of the compounds were more potent against MES induced convulsions than INH induced convulsions. Schiff bases of benzothiazol-2-ylamine were more effective than thiazolo [5, 4-b] pyridin-2-ylamine against MES induced convulsions. The compound benzothiazol-2-yl-(1H-indol-2-ylmethylene)-amine (VI) was the most potent member of the series against both types of convulsions. Compound VI exhibited the most significant activity profile in both the models. The compounds did not exhibit any carcinogenicity or acute toxicity in the in-silico studies. Thus, it may be concluded that the Schiff bases of benzothiazol-2-ylamine exhibit the potential to be promising and non-toxic anticonvulsant agents.
15. Conversion of 2-deoxy-D-ribose into 2-amino-5-(2-deoxy-beta-D-ribofuranosyl)pyridine, 2'-deoxypseudouridine, and other C-(2'-deoxyribonucleosides).
Science.gov (United States)
Reese, Colin B; Wu, Qinpei
2003-09-21
The synthesis of 2-amino-5-(2-deoxy-beta-D-ribofuranosyl)pyridine 2a, 2-amino-5-(2-deoxy-alpha-D-ribofuranosyl)-pyridine 23, 2-amino-5-(2-deoxy-beta-D-ribofuranosyl)-3-methylpyridine 2b, 2-amino-5-(2-deoxy-alpha-D-ribofuranosyl)-3-methylpyridine 29 and 5-(2-deoxy-beta-D-ribofuranosyl)-2,4-dioxopyrimidine [2'-deoxypseudouridine] 30a is described. These C-nucleosides are prepared either from 2-deoxy-3,5-O-(1,1,3,3-tetraisopropyldisiloxan-1,3-diyl)-D-ribofuranose 15 or from 2-deoxy-3,5-O-(1,1,3,3-tetraisopropyldisiloxan-1,3-diyl)-D-ribono-1,4-lactone 16, which are themselves prepared from 2-deoxy-D-ribose 13. The sugar derivatives are first allowed to react with the appropriate 5-lithio-pyridine or 5-lithio-pyrimidine derivatives, which are prepared from 5-bromo-2-(dibenzylamino)pyridine 12a, 5-bromo-2-[bis(4-methoxybenzyl)amino]pyridine 12b, 5-bromo-2-dibenzylamino-3-methylpyridine 25 and 5-bromo-2,4-bis(4-methoxybenzyloxy)pyrimidine 33. The products from the reactions between the lithio-derivatives and the lactol 15 are cyclized under Mitsunobu conditions; the products from the reactions between the lithio-derivatives and the lactone 16 are first reduced with L-Selectride before cyclization, also under Mitsunobu conditions. In all cases, the beta-anomers of the protected C-nucleosides are the predominant products. Finally, the separation of the alpha- and beta-anomers and the removal of all of the protecting groups are described.
16. Complexation reactions in pyridine and 2,6-dimethylpyridine-water system: The quantum-chemical description and the path to liquid phase separation
Science.gov (United States)
Chernia, Zelig; Tsori, Yoav
2018-03-01
Phase separation in substituted pyridines in water is usually described as an interplay between temperature-driven breakage of hydrogen bonds and the associating interaction of the van der Waals force. In previous quantum-chemical studies, the strength of hydrogen bonding between one water and one pyridine molecules (the 1:1 complex) was assigned a pivotal role. It was accepted that the disassembly of the 1:1 complex at a critical temperature leads to phase separation and formation of the miscibility gap. Yet, for over two decades, notable empirical data and theoretical arguments were presented against that view, thus revealing the need in a revised quantum-mechanical description. In the present study, pyridine-water and 2,6-dimethylpyridine-water systems at different complexation stages are calculated using high level Kohn-Sham theory. The hydrophobic-hydrophilic properties are accounted for by the polarizable continuum solvation model. Inclusion of solvation in free energy of formation calculations reveals that 1:1 complexes are abundant in the organically rich solvents but higher level oligomers (i.e., 2:1 dimers with two pyridines and one water molecule) are the only feasible stable products in the more polar media. At the critical temperature, the dissolution of the external hydrogen bonds between the 2:1 dimer and the surrounding water molecules induces the demixing process. The 1:1 complex acts as a precursor in the formation of the dimers but is not directly involved in the demixing mechanism. The existence of the miscibility gap in one pyridine-water system and the lack of it in another is explained by the ability of the former to maintain stable dimerization. Free energy of formation of several reaction paths producing the 2:1 dimers is calculated and critically analyzed.
17. Automated synthesis of an {sup 18}F-labelled pyridine-based alkylating agent for high yield oligonucleotide conjugation
Energy Technology Data Exchange (ETDEWEB)
Guggenberg, Elisabeth von; Sader, Jayden A.; Wilson, John S.; Shahhosseini, Soraya; Koslowsky, Ingrid; Wuest, Frank [Edmonton PET Centre, Division of Oncologic Imaging, Department of Oncology, Cross Cancer Institute, 11560 University Ave, Edmonton, AB, T6G 1Z2 (Canada); Mercer, John R. [Edmonton PET Centre, Division of Oncologic Imaging, Department of Oncology, Cross Cancer Institute, 11560 University Ave, Edmonton, AB, T6G 1Z2 (Canada)], E-mail: [email protected]
2009-09-15
Alkylating agents have been shown to be very promising for the radiolabelling of oligonucleotides with fluorine-18. In this report we describe the fully automated synthesis of 2-bromo-N-[3-(2-[{sup 18}F]fluoropyridin-3-yloxy)propyl]acetamide ([{sup 18}F]FPyBrA) utilizing a modular synthesis unit. Reaction conditions for the coupling of this pyridine-based alkylating agent at the 5' end of a fully phosphorothioated random 20-mer DNA sequence were optimized to achieve very high radiochemical yields (>90%) and a maximum specific activity of 5-6 GBq/{mu}moL. The potential for rapid purification by solid phase extraction without need of chromatographic isolation of the radiolabelled oligonucleotide presents an overall benefit for the application of oligonucleotides in preclinical studies and potential clinical applications.
18. G-quadruplex induced chirality of methylazacalix[6]pyridine via unprecedented binding stoichiometry: en route to multiplex controlled molecular switch
Science.gov (United States)
Guan, Ai-Jiao; Shen, Meng-Jie; Xiang, Jun-Feng; Zhang, En-Xuan; Li, Qian; Sun, Hong-Xia; Wang, Li-Xia; Xu, Guang-Zhi; Tang, Ya-Lin; Xu, Li-Jin; Gong, Han-Yuan
2015-05-01
Nucleic acid based molecular device is a developing research field which attracts great interests in material for building machinelike nanodevices. G-quadruplex, as a new type of DNA secondary structures, can be harnessed to construct molecular device owing to its rich structural polymorphism. Herein, we developed a switching system based on G-quadruplexes and methylazacalix[6]pyridine (MACP6). The induced circular dichroism (CD) signal of MACP6 was used to monitor the switch controlled by temperature or pH value. Furthermore, the CD titration, Job-plot, variable temperature CD and 1H-NMR experiments not only confirmed the binding mode between MACP6 and G-quadruplex, but also explained the difference switching effect of MACP6 and various G-quadruplexes. The established strategy has the potential to be used as the chiral probe for specific G-quadruplex recognition.
19. Total electron scattering cross section from pyridine molecules in the energy range 10-1000 eV
Science.gov (United States)
Dubuis, A. Traoré; Costa, F.; da Silva, F. Ferreira; Limão-Vieira, P.; Oller, J. C.; Blanco, F.; García, G.
2018-05-01
We report on experimental total electron scattering cross-section (TCS) from pyridine (C5H5N) for incident electron energies between 10 and 1000 eV, with experimental uncertainties within 5-10%, as measured with a double electrostatic analyser apparatus. The experimental results are compared with our theoretical calculations performed within the independent atom model complemented with a screening corrected additivity rule (IAM-SCAR) procedure which has been updated by including interference effects. A good level of agreement is found between both data sources within the experimental uncertainties. The present TCS results for electron impact energy under study contribute, together with other scattering data available in the literature, to achieve a consistent set of cross section data for modelling purposes.
20. 6-Bromo-2-(4-chlorophenyl-3-methyl-3H-imidazo[4,5-b]pyridine
Directory of Open Access Journals (Sweden)
Selma Bourichi
2016-05-01
Full Text Available In the title compound, C13H9BrClN3, the imidazopyridine fused-ring system is almost planar, with r.m.s. deviation of 0.006 (19 Å, and makes a dihedral angle of 29.32 (8° with the mean plane of the 4-chlorophenyl group. In the crystal, C—H...N hydrogen bonds link the molecules into chains propagating in the [100] direction. Weak intermolecular π–π interactions between the five- and six-membered rings of the 3H-imidazo[4,5-b]pyridine moieties of neighbouring molecules [centroid–centroid distance = 3.8648 (12 Å] further consolidate the packing into layers parallel to the ab plane.
1. Synthesis of Some New 1,3,4-Thiadiazole, Thiazole and Pyridine Derivatives Containing 1,2,3-Triazole Moiety
Directory of Open Access Journals (Sweden)
2017-02-01
Full Text Available In this study, 1-(5-Methyl-1-(p-tolyl-1H-1,2,3-triazol-4-ylethan-1-one, was reacted with Thiosemicarbazide, alkyl carbodithioate and benzaldehyde to give thiosemicarbazone, alkylidenehydrazinecarbodithioate and 3-phenylprop-2-en-1-one-1,2,3-triazole derivatives. The 1,3,4-thiadiazole derivatives containing the 1,2,3-triazole moiety were obtained via reaction of alkylidenecarbodithioate with hydrazonoyl halides. Also, hydrazonoyl halides were reacted with thiosemicarbazone and pyrazolylthioamide to give 1,3-thiazoles derivatives. Subsequently, 3-phenyl2-en-1-one was used to synthesize substituted pyridines and substituted nicotinic acid ester. The latter was converted to its azide compound which was reacted with aromatic amines and phenol to give substituted urea and phenylcarbamate containing 1,2,3-triazole moiety. The newly synthesized compounds were established by elemental analysis, spectral data and alternative synthesis whenever possible.
2. An extractive studies on behavior of Th(IV) from malonate media by 2-octyl amino pyridine: a green approach
International Nuclear Information System (INIS)
Kore, G.D.; Patil, S.A.; Zanje, S.B.; Ghule, A.V.; Kolekar, S.S.; Anuse, M.A.
2015-01-01
Liquid-liquid extraction and separation of Th(IV) was studied using 2-octylamino pyridine (2-OAP) in xylene at 298K. The extraction behavior of Th(IV) was studied as a function of pH, acid concentration, concentration of extractants, diluents, stripping agent, shaking period, aqueous to organic phase ratio, species, interference of diverse cations and anions. The possible composition of extracted species in organic phase has been proposed by slope analysis method. The robustness of procedure was demonstrated by the average recoveries obtained (>99%) for Th(IV). The proposed method demonstrates the separation and determination of Th(IV) from binary and synthetic mixture and real samples such as Monazite and Gas mantles. (author)
3. Bis{2-[(pyridin-2-ylmethylideneamino]benzoato-κ3N,N′,O}chromium(III nitrate monohydrate
Directory of Open Access Journals (Sweden)
Elena A. Buvaylo
2014-04-01
Full Text Available The title complex salt hydrate, [Cr(C13H9N2O22]NO3·H2O, comprises discrete cations, nitrate anions and solvent water molecules. The CrIII atom is octahedrally coordinated by two anionic Schiff base ligands with the O atoms being cis. The two ligands differ significantly with dihedral angles between the pyridine and benzene rings of 4.8 (2 and 24.9 (2°. The nitrate anion and solvent water molecule were modelled as being disordered, with the major components having site-occupancy values of 0.856 (14 and 0.727 (16, respectively. The crystal is built of alternating layers of cations and of anions plus water molecules, stacked along the c axis.
4. (Z)-N,N-Dimethyl-2-[phenyl(pyridin-2-yl)methylidene]hydrazinecarbothioamide
Science.gov (United States)
Jayakumar, K.; Sithambaresan, M.; Prathapachandra Kurup, M. R.
2011-01-01
The title compound, C15H16N4S, exists in the Z conformation with the thionyl S atom lying cis to the azomethine N atom. The shortening of the N—N distance [1.3697 (17) Å] is due to extensive delocalization with the pyridine ring. The hydrazine–carbothioamide unit is almost planar, with a maximum deviation of 0.013 (2) Å for the amide N atom. The stability of this conformation is favoured by the formation of an intramolecular N—H⋯N hydrogen bond. The packing of the molecules involves no classical intermolecular hydrogen-bonding interactions; however, a C—H⋯π interaction occurs. PMID:22199715
5. Crystal structure and DFT study of (E-4-[({4-[(pyridin-2-ylmethylideneamino]phenyl}aminomethyl]phenol
Directory of Open Access Journals (Sweden)
Md. Serajul Haque Faizi
2018-03-01
Full Text Available In the title Schiff base compound, C19H17N3O, the configuration about the C=N bond is E. The molecule is non-planar, with the phenolic and pyridine rings being inclined to the central benzene ring by 56.59 (4 and 15.13 (14°, respectively. In the crystal, molecules are linked by pairs of O—H...N hydrogen bonds, forming inversion dimers. The dimers are connected to neighbouring dimers by N—H...O hydrogen bonds and C—H...π interactions, forming layers parallel to the bc plane. The layers are linked by offset π–π interactions [intercentroid distance = 3.779 (2 Å], forming a three-dimensional supramolecular structure. Quantum chemical calculations of the molecule are in good agreement with the solid-state structure.
6. A theoretical study on 3-(4-methoxyphenyl)-1-(pyridin-2-Yl) prop-2-en-1-one
Energy Technology Data Exchange (ETDEWEB)
Öner, Nazmiye, E-mail: [email protected]; Tamer, Ömer, E-mail: [email protected]; Avci, Davut, E-mail: [email protected]; Atalay, Yusuf, E-mail: [email protected] [Sakarya University, Faculty of Arts and Sciences, Department of Physics, 54187, Sakarya (Turkey)
2016-03-25
This study reports the geometric parameters, vibration frequencies, {sup 13}C and {sup 1}H NMR chemical shifts of 3-(4-Methoxyphenyl)-1-(pyridin-2-yl) prop-2-en-1-one (MPP) molecule calculated by B3LYP level of density functional theory (DFT) with 6-311++G(d,p) basis set. {sup 13}C and {sup 1}H NMR chemical shifts were calculated within GIAO approach which is one of the most common approaches. Additionally, 3D molecular surfaces such as molecular electrostatic potential (MEP) and electrostatic potential (ESP), were simulated by the same level. As a result, obtained theoretical results were found to be consistent with experimental ones. All of calculations were carried out Gaussian 09 package program.
7. Pyridine metabolism and trigonelline synthesis in leaves of the mangrove legume trees Derris indica (Millettia pinnata) and Caesalpinia crista.
Science.gov (United States)
Yin, Yuling; Sasamoto, Hamako; Ashihara, Hiroshi
2011-12-01
The aim of this study was to reveal the pyridine metabolism in leaves of two mangrove legumes, Derris indica (= Millettia pinnata or Pongamia pinnata) and Caesalpinia crista. Radioactivity from [carbonyl-14C]nicotinamide supplied exogenously to young leaf disks was recovered in nicotinic acid, nicotinic acid mononucleotide, NAD, NADP, nicotinamide mononucleotide and trigonelline. These mangrove species, especially D. indica, have strong ability to convert nicotinamide to trigonelline, but not to nicotinic acid glucoside. The endogenous trigonelline content in leaves of D. indica was more than 830 microg/g dry weight. This value is 5-12 times greater than that in leaves of Glycine max. There was little short-term effect of 250 and 500 mM NaCl (equivalent to ca. 50% and 100% sea water) on nicotinamide metabolism.
8. Sustainable production of valuable compound 3-succinoyl-pyridine by genetically engineering Pseudomonas putida using the tobacco waste.
Science.gov (United States)
Wang, Weiwei; Xu, Ping; Tang, Hongzhi
2015-11-17
Treatment of solid and liquid tobacco wastes with high nicotine content remains a longstanding challenge. Here, we explored an environmentally friendly approach to replace tobacco waste disposal with resource recovery by genetically engineering Pseudomonas putida. The biosynthesis of 3-succinoyl-pyridine (SP), a precursor in the production of hypotensive agents, from the tobacco waste was developed using whole cells of the engineered Pseudomonas strain, S16dspm. Under optimal conditions in fed-batch biotransformation, the final concentrations of product SP reached 9.8 g/L and 8.9 g/L from aqueous nicotine solution and crude suspension of the tobacco waste, respectively. In addition, the crystal compound SP produced from aqueous nicotine of the tobacco waste in batch biotransformation was of high purity and its isolation yield on nicotine was 54.2%. This study shows a promising route for processing environmental wastes as raw materials in order to produce valuable compounds.
9. Synthesis, Structures and Properties of Cobalt Thiocyanate Coordination Compounds with 4-(hydroxymethyl)pyridine as Co-ligand
OpenAIRE
Stefan Suckert; Luzia S. Germann; Robert E. Dinnebier; Julia Werner; Christian Näther
2016-01-01
Reaction of Co(NCS)2 with 4-(hydroxymethyl)pyridine (hmpy) leads to the formation of six new coordination compounds with the composition [Co(NCS)2(hmpy))4] (1), [Co(NCS)2(hmpy)4] × H2O (1-H2O), [Co(NCS)2(hmpy)2(EtOH)2] (2), [Co(NCS)2(hmpy)2(H2O)2] (3), [Co(NCS)2(hmpy)2]n∙4 H2O (4) and [Co(NCS)2(hmpy)2]n (5). They were characterized by single crystal and powder X-ray diffraction experiments, thermal and elemental analysis, IR and magnetic measurements. Compound 1 and 1-H2O form discrete comple...
10. 5-(4-Ethoxyphenyl-3-(pyridin-2-yl-4,5-dihydro-1H-pyrazole-1-carbothioamide
Directory of Open Access Journals (Sweden)
Hoong-Kun Fun
2012-03-01
Full Text Available In the title compound, C17H18N4OS, a pyrazoline derivative, the pyrazoline ring adopts an envelope conformation with the C atom bonded to the benzene ring as the flap atom. The dihedral angle between the pyridine and benzene rings is 80.50 (6°. The ethoxyphenyl group is approximately planar, with an r.m.s. deviation of 0.0238 (1 Å for the nine non-H atoms. In the crystal, molecules are linked by N—H...O and N—H...S hydrogen bonds into a tape along the b axis. Weak C—H...N and C—H...π interactions are also observed.
11. Free radicals in an adamantane matrix. XIII. Electron paramagnetic resonance study of sigma* - π* orbital crossover in fluorinated pyridine anions
International Nuclear Information System (INIS)
Yim, M.B.; DiGregorio, S.; Wood, D.E.
1977-01-01
Pentafluoropyridine,2,3,4,6-tetrafluoropyridine, 2,6-difluoropyridine, and 2-fluoropyridine anion radicals were produced by x irradiation of an adamantane matrix which was doubly doped with the aromatic precursors and Me 3 NBH 3 and their EPR spectra obtained. The large fluorine hyperfine splitting constants (hfsc) of penta- and 2,3,4,6-tetrafluoropyridine anions and the small fluorine hfsc's of 2,6-di- and 2-fluoropyridine anions suggest that the former two are sigma radicals while the latter two are π radicals. The sigma*-π* orbital crossover phenomenon observed in these fluorinated pyridine anions is explained in terms of the combined effects of stabilization of sigma* orbitals and destabilization of π* orbitals. The EPR results show that nitrogen has a negligible contribution to the unpaired electron sigma* orbitals. INDO calculations were performed for the various states and the results compared with experiment
12. Amide-N-oxide heterosynthon and amide dimer homosynthon in cocrystals of carboxamide drugs and pyridine N-oxides.
Science.gov (United States)
Babu, N Jagadeesh; Reddy, L Sreenivas; Nangia, Ashwini
2007-01-01
The carboxamide-pyridine N-oxide heterosynthon is sustained by syn(amide)N-H...O-(oxide) hydrogen bond and auxiliary (N-oxide)C-H...O(amide) interaction (Reddy, L. S.; Babu, N. J.; Nangia, A. Chem. Commun. 2006, 1369). We evaluate the scope and utility of this heterosynthon in amide-containing molecules and drugs (active pharmaceutical ingredients, APIs) with pyridine N-oxide cocrystal former molecules (CCFs). Out of 10 cocrystals in this study and 7 complexes from previous work, amide-N-oxide heterosynthon is present in 12 structures and amide dimer homosynthon occurs in 5 structures. The amide dimer is favored over amide-N-oxide synthon in cocrystals when there is competition from another H-bonding functional group, e.g., 4-hydroxybenzamide, or because of steric factors, as in carbamazepine API. The molecular organization in carbamazepine.quinoxaline N,N'-dioxide 1:1 cocrystal structure is directed by amide homodimer and anti(amide)N-H...O-(oxide) hydrogen bond. Its X-ray crystal structure matches with the third lowest energy frame calculated in Polymorph Predictor (Cerius(2), COMPASS force field). Apart from generating new and diverse supramolecular structures, hydration is controlled in one substance. 4-Picoline N-oxide deliquesces within a day, but its cocrystal with barbital does not absorb moisture at 50% RH and 30 degrees C up to four weeks. Amide-N-oxide heterosynthon has potential utility in both amide and N-oxide type drug molecules with complementary CCFs. Its occurrence probability in the Cambridge Structural Database is 87% among 27 structures without competing acceptors and 78% in 41 structures containing OH, NH, H(2)O functional groups.
13. On the isomers of pyridine-4-carboxaldoxime and its nitrate salt, X-ray crystal structure and quantum chemical calculations
Science.gov (United States)
Soliman, Saied M.; Albering, Jörg; Abu-Youssef, Morsy A. M.
2017-07-01
The reaction between nitric acid and pyridine-4-carboxaldoxime (P4A) afford the corresponding pyridinum nitrate salt (P4AN). Its X-ray structure is measured and compared with the related P4A salts. The DFT/B3LYP results showed that both the P4A and P4AN favored the Syn-I form which has the lowest energy among the other possible isomers. Transition state calculations predicted that the Syn-I form is the thermodynamically and kinetically most stable form. The X-ray solid state structure of the new nitrate salt (P4AN) indicated that the labile proton favored the N-atom of the pyridine ring. DFT studies showed that the same is true for its solution in polar solvents. In contrast, the pyridinium cation is not favored either in the gas phase or solution of P4AN in nonpolar solvent. In these cases, the proton favored to bond with one O-atom from the nitrate group. Second order interaction energies and Mayer bond order values revealed these results. The bond order of the Nsbnd H bond is higher in polar solvents as well as at the experimental structure than either in the gas phase or non polar solvents. The topology parameters obtained from the atoms in molecules (AIM) analysis were used to describe the nature of the Nsbnd H and Osbnd H bonds. The bond critical points (BCP) were found to be close to the H-atoms in case of stronger interaction.
14. Secondary ligand-directed assembly of Co(II) coordination polymers based on a pyridine carboxylate ligand
International Nuclear Information System (INIS)
Cao, Ke-Li; Zhang, Yi-Ping; Cai, Yi-Ni; Xu, Xiao-Wei; Feng, Yun-Long
2014-01-01
To investigate the influence of hydrogen bonds and secondary ligands on the structures and properties of the resulting frameworks, five new Co(II) compounds have been synthesized by the reactions of Co(II) salts and 3,5-bis(pyridin-4-ylmethoxy)benzoic acid (HL) with four rationally selected dicarboxylic acid ligands. Without secondary ligand, we got one compound [CoL 2 (H 2 O) 2 ] n ·2nH 2 O (1), which possesses a 1D chain structure. In the presence of ancillary ligands, namely, 1,3-adamantanedicarboxylic acid (H 2 adbc), terephthalic acid (H 2 tpa), thiophene-2,5-dicarboxylic acid (H 2 tdc) and 1,4-benzenedithioacetic acid (H 2 bdtc), four 3D structures [Co 2 L 2 (adbc)] n ·nH 2 O (2), [Co 2 L 2 (tpa)] n (3), [Co 2 L 2 (tdc)] n (4), [Co 2 L 2 (bdtc)(H 2 O)] n (5) were obtained, respectively. It can be observed from the architectures of 1–5 that hydrogen bonds and secondary ligands both have great effects on the spatial connective fashions, resulting in the formation of various dimensional compounds. The XRPD, TGA data of title polymers and the magnetic properties for 2 and 5 have also been investigated. - Graphical abstract: The structural differences show that the ancillary ligands have great effects on the spatial connective fashions, resulting in the formation of various dimensional compounds. - Highlights: • Five new Co(II) coordination polymers have been synthesized by solvothermal reactions based on 3,5-bis(pyridin-4-ylmethoxy)benzoic acid (HL). • The long-flexible ligand (HL) is a good candidate to produce interpenetrating architectures. • The secondary dicarboxylic acid ligands play important roles in the spatial connective fashions and the formation of various dimensional compounds. • The magnetism studies show that both 2 and 5 exhibit antiferromagnetic interactions
15. Comparative pharmacokinetic study of dosage forms with morpholinium 2-[5-(pyridin-4-yl-1,2,4-triazol-3-ylthio] acetate
Directory of Open Access Journals (Sweden)
I. V. Bushueva
2014-12-01
Full Text Available Using mathematical models of income distribution and excretion of drugs greatly enhances the interpretation of the results of biopharmaceutical research. Pharmacokinetic modeling makes it possible to quantify the biological assessment of pharmaceutical factors, opens the possibility of a science-based regulation of the kinetics of substances introduced through targeted changesof pharmaceutical factors. Results of the study of kinetic models are used to solve some practical problems associated with pharmacological and clinical trials of medicines. Morpholinium 2-[5-(pyridin-4-yl-1,2,4-triazol-3-ylthio] acetate is new organic compound from the 1,2,4-triazole group obtained at the Department of Inorganic Chemistry, Zaporozhye State Medical University. The substance has antioxidant and anti-ischemic action, low toxicity. Aim of this work is to study the kinetics of absorption of morpholinium 2-[5-(pyridin-4-yl-1,2,4-triazol-3-ylthio] acetate developed formulations. MATERIALS AND METHODS Pharmacokinetic studies of oral and rectal dosage forms of morpholinium 2-[5-(pyridin-4-yl-1,2,4-triazol-3-ylthio] acetate was performed on Chinchilla rabbits weighing an average of 2.5 kg, divided into three groups. The third group for comparison was administered a 1% injectable solution of morpholinium 2-[5-(pyridin-4-yl-1,2,4-triazol-3-ylthio] acetate intravenously. Substance dose was 0.1 g and 0.5 g per kg of animal body weight, which were administered once. Sampling from the auricular vein of the rabbits was performed at 5, 10, 15, 30, 45, 60, 75, 90, 120, 150 and 180 minutes after oral administration and rectal dosage forms of morpholinium 2-[5-(pyridin-4-yl-1,2,4-triazol-3-ylthio] acetate and after 3, 5, 10, 15, 20, 30, 40, 50 and 60 minutes after intravenous injection. Morpholinium 2-[5-(pyridin-4-yl-1,2,4-triazol-3-ylthio] acetate concentration in serum was adjusted spectrophotometrically. Results.Morpholinium 2-[5-(pyridin-4-yl-1,2,4-triazol-3-ylthio
16. Characterization of a hybrid-smectite nanomaterial formed by immobilizing of N-pyridin-2-ylmethylsuccinamic acid onto (3-aminopropyl)triethoxysilane modified smectite and its potentiometric sensor application
Science.gov (United States)
Topcu, Cihan; Caglar, Sema; Caglar, Bulent; Coldur, Fatih; Cubuk, Osman; Sarp, Gokhan; Gedik, Kubra; Bozkurt Cirak, Burcu; Tabak, Ahmet
2016-09-01
A novel N-pyridin-2-ylmethylsuccinamic acid-functionalized smectite nanomaterial was synthesized by immobilizing of N-pyridin-2-ylmethylsuccinamic acid through chemical bonding onto (3-aminopropyl)triethoxysilane modified smectite. The structural, thermal, morphological and surface properties of raw, silane-grafted and the N-pyridin-2-ylmethylsuccinamic acid-functionalized smectites were investigated by various characterization techniques. The thermal analysis data showed the presence of peaks in the temperature range from 200 °C to 600 °C due to the presence of physically adsorbed silanes, intercalated silanes, surface grafted silanes and chemically grafted silane molecules between the smectite layers. The powder x-ray diffraction patterns clearly indicated that the aminopropyl molecules also intercalated into the smectite interlayers as bilayer arrangement whereas N-pyridin-2-ylmethylsuccinamic acid molecules were only attached to 3-aminopropyltriethoxysilane molecules on the external surface and edges of clay and they did not intercalate. Fourier transform infrared spectroscopy confirms N-pyridin-2-ylmethylsuccinamic acid molecules bonding through the amide bond between the amine group of aminopropyltriethoxysilane molecules and a carboxylic acid functional group of N-pyridin-2-ylmethylsuccinamic acid molecules. The guest molecules functionalized onto the smectite caused significant alterations in the textural and morphological parameters of the raw smectite. The anchoring of N-pyridin-2-ylmethylsuccinamic acid molecules led to positive electrophoretic mobility values when compared to starting materials. N-pyridin-2-ylmethylsuccinamic acid-functionalized smectite was employed as an electroactive ingredient in the structure of potentiometric PVC-membrane sensor. The sensor exhibited more selective potentiometric response towards chlorate ions compared to the other common anionic species.
17. Synthesis of 2-(5-Nitropyrid-2-yl-3-(4-substitutedphenylaminoisoxazol-5(2H-ones and Their Rearrangements to Imidazo[1,2-a]- pyridines and Indoles with Triethylamine
Directory of Open Access Journals (Sweden)
K. Akbari Dilmaghani
2002-12-01
Full Text Available 3-(4-Substitutedphenylaminoisoxazol-5(2H-ones, substituted on nitrogen with a nitropyridine group, react with triethylamine to give imidazo[1,2-a]pyridines and indoles. With 4-bromophenyl and 4-methylphenyl group substituents only imidazopyridines are formed, but the 4-methoxyphenyl derivative gave a 3:1 mixture of the corresponding imidazo[1,2-a]pyridine and 2-pyridylaminoindole, respectively.
18. The novel imidazopyridine 2-[2-(4-methoxy-pyridin-2-yl)-ethyl]-3H-imidazo[4,5-b]pyridine (BYK191023) is a highly selective inhibitor of the inducible nitric-oxide synthase.
Science.gov (United States)
Strub, Andreas; Ulrich, Wolf-Rüdiger; Hesslinger, Christian; Eltze, Manfrid; Fuchss, Thomas; Strassner, Jochen; Strand, Susanne; Lehner, Martin D; Boer, Rainer
2006-01-01
We have identified imidazopyridine derivatives as a novel class of NO synthase inhibitors with high selectivity for the inducible isoform. 2-[2-(4-Methoxy-pyridin-2-yl)-ethyl]-3H-imidazo[4,5-b]pyridine (BYK191023) showed half-maximal inhibition of crudely purified human inducible (iNOS), neuronal (nNOS), and endothelial (eNOS) NO synthases at 86 nM, 17 microM, and 162 microM, respectively. Inhibition of inducible NO synthase was competitive with l-arginine, pointing to an interaction of BYK191023 with the catalytic center of the enzyme. In radioligand and surface plasmon resonance experiments, BYK191023 exhibited an affinity for iNOS, nNOS, and eNOS of 450 nM, 30 microM, and >500 microM, respectively. Inhibition of cellular nitrate/nitrite synthesis in RAW, rat mesangium, and human embryonic kidney 293 cells after iNOS induction showed 40- to 100-fold higher IC(50) values than at the isolated enzyme, in agreement with the much higher l-arginine concentrations in cell culture media and inside intact cells. BYK191023 did not show any toxicity in various rodent and human cell lines up to high micromolar concentrations. The inhibitory potency of BYK191023 was tested in isolated organ models of iNOS (lipopolysaccharide-treated and phenylephrine-precontracted rat aorta; IC(50) = 7 microM), eNOS (arecaidine propargyl ester-induced relaxation of phenylephrine-precontracted rat aorta; IC(50) > 100 microM), and nNOS (field-stimulated relaxation of phenylephrine-precontracted rabbit corpus cavernosum; IC(50) > 100 microM). These data confirm the high selectivity of BYK191023 for iNOS over eNOS and nNOS found at isolated enzymes. In summary, we have identified a new highly selective iNOS inhibitor structurally unrelated to known compounds and l-arginine. BYK191023 is a valuable tool for the investigation of iNOS-mediated effects in vitro and in vivo.
19. 2-Amino-1-methyl-6-(5-hydroxy-)phenylimidazo[4,5-b]pyridine (5-OH-PhIP), a biomarker for the genotoxic dose of the heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)
DEFF Research Database (Denmark)
Frandsen, H; Frederiksen, H; Alexander, J
2002-01-01
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a mutagenic and carcinogenic heterocyclic amine formed during ordinary cooking. PhIP is metabolically activated by CYP P450 mediated N-hydroxylation followed by phase II esterification. The ultimate mutagenic metabolite reacts with DNA...
20. N-{(Z-3-Oxo-3-[(E-(pyridin-2-ylmethyldiazenyl]-1-(thiophen-2-ylprop-1-en-2-yl}benzamide
Directory of Open Access Journals (Sweden)
Devinder K. Sharma
2016-08-01
Full Text Available In the title compound, C20H16N4O2S, the thiophene ring subtends dihedral angles of 58.6 (3 and 9.8 (3° with the benzamide and pyridine rings, respectively, whereas these two rings are inclined to one another by 59.3 (3°. There is an intramolecular C—H...π interaction present involving the pyridine and benzamide rings. In the crystal, molecules are linked by N—H...O hydrogen bonds, forming chains along the [010] direction. The chains are linked by C—H...S hydrogen bonds and C—H...π interactions, forming sheets parallel to the ab plane.
Directory of Open Access Journals (Sweden)
Najmeh Firoozi
2008-10-01
Full Text Available In the title compound, (C4H14N2[Cd(C7H3NO42]·2H2O, the CdII ion is coordinated by four O atoms [Cd—O = 2.2399 (17–2.2493 (17 Å] and two N atoms [Cd—N = 2.3113 (15 and 2.3917 (15 Å] from two tridentate pyridine-2,6-dicarboxylato ligands in a distorted octahedral geometry. The uncoordinated water molecules are involved in O—H...O and N—H...O hydrogen bonds, which contribute to the formation of a three-dimensional supramolecular structure, along with π–π stacking interactions [centroid–centroid distances of 3.5313 (13 and 3.6028 (11 Å between the pyridine rings of neighbouring dianions].
2. Tetrel, Chalcogen, and Charge-Assisted Hydrogen Bonds in 2-((2-Carboxy-1-(substituted-2-hydroxyethylthio Pyridin-1-ium Chlorides
Directory of Open Access Journals (Sweden)
Firudin I. Guseinov
2017-10-01
Full Text Available Reaction of 2-chloro-2-(diethoxymethyl-3-substitutedoxirane or 1-chloro-1-(substituted -3,3-diethoxypropan-2-one with pyridine-2-thiol in EtOH at 25 °C yields 3-(diethoxymethyl-3-hydroxy-2-substituted-2,3-dihydrothiazolo[3,2-a]pyridin-4-ium chlorides, which subsequently, in MeCN at 85°C, transforms into ring-opening products, 2-((2-carboxy-1-(substituted -2-hydroxyethylthiopyridin-1-ium chlorides. The tetrel (C···O and chalcogen (S···O bonds are found in the structures of 5 and 6, respectively. Compound 6 is also present in halogen bonding with a short O···Cl distance (3.067 Å. Both molecules are stabilized in crystal by tetrel, chalcogen, and multiple charge-assisted hydrogen bonds.
3. CuI nanoparticles as new, efficient and reusable catalyst for the one-pot synthesis of 1,4-dihydro pyridines
International Nuclear Information System (INIS)
Safaeighomi, Javad; Ziarati, Abolfazl; Teymuri, Raheleh
2012-01-01
A simple one-pot synthesis of two derivatives of 1,4-dihydro pyridines has been described under reflux conditions using copper iodide nanoparticles (CuI NPs) as a catalyst in high yields. This method demonstrated four-component coupling reactions of aldehydes and ammonium acetate via two pathways. In one route, the reaction was performed using 2 eq ethyl acetoacetate while in the other one 1 eq ethyl acetoacetate and 1 eq malononitrile were used. The CuI NPs was reused and recycled without any loss of activity and product yield. It is noteworthy to state that wide range of the 1,4-dihydro pyridines have attracted large interest due to pharmacological and biological activities
4. 6-Bromo-1,3-di-2-propynyl-1H-imidazo[4,5-b]pyridin-2(3H-one
Directory of Open Access Journals (Sweden)
S. Dahmani
2010-04-01
Full Text Available The room-temperature reaction of propargyl bromide and 6-bromo-1,3-dihydroimidazo[4,5-b]pyridin-2-one in dimethylformamide yields the title compound, C12H8BrN3O, which features nitrogen-bound propynyl substituents. The imidazopyridine fused ring is almost planar (r.m.s. deviation = 0.011 Å; the propynyl chains point in opposite directions relative to the fused ring. One acetylenic H atom is hydrogen bonded to the carbonyl O atom of an inversion-related molecule, forming a dimer; adjacent dimers are linked by a second acetylene–pyridine C—H...N interaction, forming a layer motif.
5. N-[5-Methyl-2-(2-nitro-phen-yl)-4-oxo-1,3-thia-zolidin-3-yl]pyridine-3-carboxamide monohydrate.
Science.gov (United States)
Akkurt, Mehmet; Celik, Ismail; Demir, Hale; Ozkırımlı, Sumru; Büyükgüngör, Orhan
2011-01-08
In the title compound, C(16)H(14)N(4)O(4)S·H(2)O, the benzene and pyridine rings make a dihedral angle of 85.8 (1)°. Both enanti-omers of the chiral title compound are statistically disordered over the same position in the unit cell. The methyl and carbonyl group attached to the stereogenic center (C(5) of the thia-zolidine ring) were therefore refined with common site-occupation factors of 0.531 (9) and 0.469 (9), respectively, for each stereoisomer. In the crystal, inter-molecular N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds link the mol-ecules, forming a three-dimensional supra-molecular network. The crystal structure further shows π-π stacking inter-actions [centroid-centroid distance = 3.5063 (13) Å] between the pyridine rings.
6. Synthesis of Imidazopyridines via Copper-Catalyzed, Formal Aza-[3 + 2] Cycloaddition Reaction of Pyridine Derivatives with α-Diazo Oxime Ethers.
Science.gov (United States)
Park, Sangjune; Kim, Hyunseok; Son, Jeong-Yu; Um, Kyusik; Lee, Sooho; Baek, Yonghyeon; Seo, Boram; Lee, Phil Ho
2017-10-06
The Cu-catalyzed, formal aza-[3 + 2] cycloaddition reaction of pyridine derivatives with α-diazo oxime ethers in trifluoroethanol was used to synthesize imidazopyridines via the release of molecular nitrogen and elimination of alcohol. These methods enabled modular synthesis of a wide range of N-heterobicyclic compounds such as imidazopyridazines, imidazopyrimidines, and imidazopyrazines with an α-imino Cu-carbenoid generated from the α-diazo oxime ethers and copper.
7. Methoxyphenylethynyl, methoxypyridylethynyl and phenylethynyl derivatives of pyridine: synthesis, radiolabeling and evaluation of new PET ligands for metabotropic glutamate subtype 5 receptors
International Nuclear Information System (INIS)
Yu Meixiang; Tueckmantel, Werner; Wang, Xukui; Zhu Aijun; Kozikowski, Alan P.; Brownell, Anna-Liisa
2005-01-01
We have synthesized three different PET ligands to investigate the physiological function of metabotropic glutamate subtype 5 receptors (mGluR5) in vivo: 2-[ 11 C]methyl-6-(2-phenylethynyl)pyridine ([ 11 C]MPEP), 2-(2-(3-[ 11 C]methoxyphenyl)ethynyl)pyridine ([ 11 C]M-MPEP) and 2-(2-(5-[ 11 C]methoxypyridin-3-yl)ethynyl)pyridine ([ 11 C]M-PEPy). [ 11 C]Methyl iodide was used to label the compounds under basic conditions, and a Pd(0) catalyst was applied to label [ 11 C]MPEP in a Stille coupling reaction. In vivo microPET imaging studies of the functional accumulation of radiolabeled ligands were conducted in 35 rats (Sprague-Dawley, 8 weeks old male, weight of 300 g). Specific binding was tested using pre-administration of unlabeled mGluR5 antagonist 2-methyl-6-(2-phenylethynyl)pyridine (MPEP) (10 mg/kg iv 5 min before radioactivity injection). In the radiolabeling of [ 11 C]MPEP, [ 11 C]M-MPEP and [ 11 C]M-PEPy, a specific radioactivity of 700-1200 mCi/μmol and over 97% radiochemical purity were obtained. The microPET studies showed these three radiolabeled mGluR5 antagonists having the highest binding in the olfactory bulb followed by striatum, hippocampus and cortex. Pre-administration of the mGluR5 antagonist MPEP induced a 45.1% decrease in [ 11 C]MPEP binding, a 59.7% decrease in [ 11 C]M-MPEP binding and an 84.6% decrease in [ 11 C]M-PEPy binding in the olfactory bulb at 5 min. The feasibility of synthesizing high-affinity and high-selectivity ligands for mGluR5 receptors and their suitability as PET imaging ligands for mGluR5 receptors in vivo are demonstrated
8. Discovery of (pyridin-4-yl)-2H-tetrazole as a novel scaffold to identify highly selective matrix metalloproteinase-13 inhibitors for the treatment of osteoarthritis.
Science.gov (United States)
Schnute, Mark E; O'Brien, Patrick M; Nahra, Joe; Morris, Mark; Howard Roark, W; Hanau, Cathleen E; Ruminski, Peter G; Scholten, Jeffrey A; Fletcher, Theresa R; Hamper, Bruce C; Carroll, Jeffery N; Patt, William C; Shieh, Huey S; Collins, Brandon; Pavlovsky, Alexander G; Palmquist, Katherine E; Aston, Karl W; Hitchcock, Jeffrey; Rogers, Michael D; McDonald, Joseph; Johnson, Adam R; Munie, Grace E; Wittwer, Arthur J; Man, Chiu-Fai; Settle, Steven L; Nemirovskiy, Olga; Vickery, Lillian E; Agawal, Arun; Dyer, Richard D; Sunyer, Teresa
2010-01-15
Potent, highly selective and orally-bioavailable MMP-13 inhibitors have been identified based upon a (pyridin-4-yl)-2H-tetrazole scaffold. Co-crystal structure analysis revealed that the inhibitors bind at the S(1)(') active site pocket and are not ligands for the catalytic zinc atom. Compound 29b demonstrated reduction of cartilage degradation biomarker (TIINE) levels associated with cartilage protection in a preclinical rat osteoarthritis model. Copyright 2009 Elsevier Ltd. All rights reserved.
9. catena-Poly[[bis(pyridine-κNnickel(II]-μ-oxalato-κ4O1,O2:O1′,O2′
Directory of Open Access Journals (Sweden)
Zhen-Yu Xuan
2008-08-01
Full Text Available The title compound, [Ni(C2O4(C5H5N2]n, was synthesized under hydro(solvothermal conditions. The NiII atom, lying on a twofold rotation axis, has an octahedral coordination geometry involving two N atoms from two pyridine ligands and four O atoms from two oxalate ligands. The Ni atoms are connected by the tetradentate bridging oxalate ligands into a one-dimensional zigzag chain.
10. A spin-crossover complex based on a 2,6-bis(pyrazol-1-yl)pyridine (1-bpp) ligand functionalized with a carboxylate group.
Science.gov (United States)
Abhervé, Alexandre; Clemente-León, Miguel; Coronado, Eugenio; Gómez-García, Carlos J; López-Jordà, Maurici
2014-07-07
Combining Fe(ii) with the carboxylate-functionalized 2,6-bis(pyrazol-1-yl)pyridine (bppCOOH) ligand results in the spin-crossover compound [Fe(bppCOOH)2](ClO4)2 which shows an abrupt spin transition with a T1/2 of ca. 380 K and a TLIESST of 60 K due to the presence of a hydrogen-bonded linear network of complexes.
11. Selective C-acylation of 2-aminoimidazo[1,2-a]pyridine: application to the synthesis of imidazopyridine-fused [1,3]diazepinones.
Science.gov (United States)
Masurier, Nicolas; Aruta, Roberta; Gaumet, Vincent; Denoyelle, Séverine; Moreau, Emmanuel; Lisowski, Vincent; Martinez, Jean; Maillard, Ludovic T
2012-04-06
A series of 20 optically pure 3,4-dihydro-5H-pyrido[1',2':1,2]imidazo[4,5-d][1,3]diazepin-5-ones which form a new family of azaheterocycle-fused [1,3]diazepines were synthesized in four steps with 17-66% overall yields. The key step consists of a selective C-acylation reaction of easily accessible 2-aminoimidazo[1,2-a]pyridine at C-3.
12. Rhodium-catalyzed NH insertion of pyridyl carbenes derived from pyridotriazoles: a general and efficient approach to 2-picolylamines and imidazo[1,5-a]pyridines.
Science.gov (United States)
Shi, Yi; Gulevich, Anton V; Gevorgyan, Vladimir
2014-12-15
A general and efficient NH insertion reaction of rhodium pyridyl carbenes derived from pyridotriazoles was developed. Various NH-containing compounds, including amides, anilines, enamines, and aliphatic amines, smoothly underwent the NH insertion reaction to afford 2-picolylamine derivatives. The developed transformation was further utilized in a facile one-pot synthesis of imidazo[1,5-a]pyridines. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
13. A new and concise strategy to the enantioselective synthesis of (S)-2-amino-4-oxo-4-(pyridine-2-yl) butanoic acid from aspartic acid
Energy Technology Data Exchange (ETDEWEB)
Lima, Evanoel Crizanto de; Souza, Carolina C. de; Maior, Marta C.L.S.; Costa, Paulo R.R., E-mail: [email protected] [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Centro de Ciencias da Saude. Nucleo de Pesquisas de Produtos Naturais; Lima, Paulo G. de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica; Dias, Ayres G. [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Inst. de Quimica
2010-07-01
The alpha-amino acid (S)-5 was synthesized using in the key step a chemoselective nucleophilic substitution between a diester derived from L-aspartic acid and 2-lithium pyridine. The overall yield (13%, 5 steps) was similar to those previously described by our group for the R isomer (the first exogen full agonist of the NMDA receptors) from D-mannitol (12%, 10 steps) and by Lovey and Copper for the racemic synthesis (17%, 5 steps). (author)
14. Mono(pyridine-N-oxide) analog of DOTA as a suitable organic reagent for a sensitive and selective fluorimetric determination of Ln(III) ions
Energy Technology Data Exchange (ETDEWEB)
Vanek, Jakub [Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Lubal, Premysl, E-mail: [email protected] [Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Sevcikova, Romana [Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Polasek, Miloslav; Hermann, Petr [Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40, Prague (Czech Republic)
2012-08-15
The mono(pyridine-N-oxide) analog of the H{sub 4}dota macrocylic ligand, H{sub 3}do3a-py{sup NO}, is capable of forming thermodynamically stable and kinetically inert Ln(III) complexes. Its Eu(III) and Tb(III) complexes display a strong long-lived fluorescence as a result of the antenna effect of the pyridine-N-oxide fluorophore in the reagent. It is shown that H{sub 3}do3a-py{sup NO} can be used as a fluorogenic reagent for the determination of Eu(III) and Tb(III) at pH 6.5 and c{sub L}=1 mM. At an excitation wavelength of 286 nm, the emission maxima are 615 nm (Eu(III)-complex), and 547 nm (Tb(III)complex). Detection limits are at concentrations around 1.0 {mu}M and linearity of the method spans over 2 orders of magnitude. The method was applied to artificial and real samples (spiked mineral waters, extracts from cathode ray tube luminophore dust) and gave satisfactory results. The method is simple, rapid, and hardly interfered by other metal ions. - Graphical Abstract: A DOTA-like ligand with pyridine-N-oxide pendant arm is used for a quick, selective and sensitive determination of Eu{sup 3+} and Tb{sup 3+} ions through sensitized emission with excitation at 286 nm. The presented fluorimetric method is not interfered by transition metal or other lanthanide(III) ions and has a high dynamic range. Highlights: Black-Right-Pointing-Pointer Quick, selective and sensitive determination of Eu{sup 3+}/Tb{sup 3+} ions was developed. Black-Right-Pointing-Pointer Sensitized emission with excitation at 286 nm through pyridine-N-oxide pendant arm. Black-Right-Pointing-Pointer No interference of transition metal or other Ln(III) ions within high dynamic range.
15. Polyethylene Glycol (PEG-400: An Efficient and Recyclable Reaction Medium for the Synthesis of Pyrazolo[3,4-b]pyridin-6(7H-one Derivatives
Directory of Open Access Journals (Sweden)
Deming Wang
2013-10-01
Full Text Available A mild and efficient synthesis of pyrazolo[3,4-b]pyridine-6(7H-one derivatives via a three-component reaction of an aldehyde, Meldrum’s acid and 3-methyl-1H-pyrazol-5-amine using recyclable polyethylene glycol (PEG-400 as a reaction medium is described. This method has the advantages of accessible starting materials, good yields, mild reaction conditions and begin environmentally friendly.
16. The silver(I nitrate complex of the ligand N-(pyridin-2-ylmethylpyrazine-2-carboxamide: a metal–organic framework (MOF structure
Directory of Open Access Journals (Sweden)
Dilovan S. Cati
2017-04-01
Full Text Available The reaction of silver(I nitrate with the mono-substituted pyrazine carboxamide ligand, N-(pyridin-2-ylmethylpyrazine-2-carboxamide (L, led to the formation of the title compound with a metal–organic framework (MOF structure, [Ag(C11H10N4O(NO3]n, poly[μ-nitrato-[μ-N-(pyridin-2-ylmethyl-κNpyrazine-2-carboxamide-κN4]silver(I]. The silver(I atom is coordinated by a pyrazine N atom, a pyridine N atom, and two O atoms of two symmetry-related nitrate anions. It has a fourfold N2O2 coordination sphere, which can be described as distorted trigonal–pyramidal. The ligands are bridged by the silver atoms forming –Ag–L–Ag–L– zigzag chains along the a-axis direction. The chains are arranged in pairs related by a twofold screw axis. They are linked via the nitrate anions, which bridge the silver(I atoms in a μ2 fashion, forming the MOF structure. Within the framework there are N—H...O and C—H...O hydrogen bonds present.
17. Synthesis of new trihalo methylated and non-symmetrical substituted 2-(1H-pyrazolyl)-5-(1H-pyrazolylcarbonyl)pyridines
International Nuclear Information System (INIS)
Bonacorso, Helio G.; Paim, Gisele R.; Guerra, Carolina Z.; Sehnem, Ronan C.; Cechinel, Cleber A.; Porte, Liliane M. F.; Martins, Marcos A. P.; Zanatta, Nilo
2009-01-01
This paper describes the synthesis of a new series of 2-[3-alkyl(aryl/heteroaryl)-5-trifluoro(chloro)methyl-5-hydroxy-4,5-dihydro -1H-pyrazol-1-yl]-5- [3-alkyl(aryl/heteroaryl)-5-trifluoro(chloro)methyl-5-hydroxy= -4,5-dihydro-1H-pyrazol-1-yl-1-carbonyl] pyridines by the cyclocondensation reaction of 4-alkoxy-4-alkyl(aryl/heteroaryl)-1,1,1- trifluoro(chloro) -3-alken- 2-ones [CX 3 C(O)CH=CR 1 OR, where R = Me, Et; R 1 = H, Me, Ph, 4-MeOPh, 4-NO 2 Ph, 4,4'-Biphenyl, 1-Naphthyl, Fur-2-yl, Thien-2-yl and X = F, Cl] with 6-hydrazinonicotinic hydrazide hydrate. Yields of 62 to 97% were obtained when the reactions were performed in ethanol as solvent at 78 deg C for 4 hours. In a subsequent step, the dehydration reactions of 2-(5-hydroxy-1H-pyrazol-1-yl)-5-(5-hydroxy-1H?pyrazol-1-yl-1-carbonyl) pyridines were carried out in pyridine/benzene in the presence of thionyl chloride and led to the isolation of a series of 2- [3-alkyl(aryl/heteroaryl)-5-trifluoro(chloro)methyl-1H-pyrazol-1-yl]-5- [3-alkyl(aryl/heteroaryl)-5 -trifluoro(chloro)methyl-1H-pyrazol-1-yl-1-carbonyl]pyridi= nes, in 64 to 86% yields. (author)
18. A Novel Bis(phosphido)pyridine [PNP] 2− Pincer Ligand and Its Potassium and Bis(dimethylamido)zirconium(IV) Complexes
KAUST Repository
Winston, Matthew S.
2010-12-13
A novel PNP bis(secondary phosphine)pyridine pincer ligand, 2,6-bis(2-(phenylphosphino)phenyl)pyridine, has been prepared in high yield, and the properties of the doubly deprotonated form as a ligand in K 4(PNP)2(THF)6 and (PNP)Zr(NMe2) 2 have been investigated. The neutral PNP ligand has been isolated as a mixture of noninterconverting diastereomers, due to the presence of two chirogenic phosphorus atoms of the secondary phopshines, but coordination of the dianionic form to potassium and zirconium allows for isolation of a single diastereomer in near-quantitative yield. The structure of a bis(dimethylamido) zirconium(IV) derivative of the bis(phosphido)pyridine ligand and DFT calculations suggest that the phosphides do not π-bond to early transition metals, likely due to geometric strain and possibly orbital size mismatch between phosphorus and zirconium. As a result, the soft phosphides are prone to formation of insoluble oligomers with substantial bridging of the phosphido lone pairs to other zirconium centers. © 2010 American Chemical Society.
19. High content of pyridinic- and pyrrolic-nitrogen-modified carbon nanotubes derived from blood biomass for the electrocatalysis of oxygen reduction reaction in alkaline medium
International Nuclear Information System (INIS)
Zheng, Jie; Guo, Chaozhong; Chen, Chunyan; Fan, Mingzhi; Gong, Jianping; Zhang, Yanfang; Zhao, Tianxin; Sun, Yuelin; Xu, Xiaofan; Li, Mengmeng; Wang, Ran; Luo, Zhongli; Chen, Changguo
2015-01-01
Graphical abstract: Display Omitted -- Highlights: •An ORR electrocatalyst was fabricated from blood biomass and carbon nanotube. •The N-CNT catalyst exhibits good ORR activity, methanol resistance and stability. •The pyrolysis process produces high contents of pyridinic and pyrrolic N species. •The pyridinic-N group may play more important role in the active sites for ORR. -- Abstract: Here we present a facile synthetic route to design nitrogen-doped nanostructured carbon-based electrocatalyst for oxygen reduction reaction (ORR) by the copyrolysis of blood biomass from pig and carbon nanotubes (CNTs) at high temperatures. The nitrogen-doped CNTs obtained at 800 °C not only results in excellent ORR activity with four-electron transfer selectivity in alkaline medium, but also exhibits superior methanol-tolerant property and long-term stability. It is confirmed that high-temperature pyrolysis processes can facilitate to produce higher contents of pyridinic- and pyrrolic-N binding groups in electrocatalysts, contributing to the enhancement of ORR performance in terms of onset potential, half-wave potential, and limited current density. We also propose that the planar-N configuration may be the active site that is responsible for the improved ORR electrocatalytic performance. The straight-forward and cheap synthesis of the active and stable electrocatalyst makes it a promising candidate for electrochemical power sources such as fuel cells or metal-air batteries
20. Crystal structure of dichlorido{2-methyl-2-[(pyridin-2-ylmethylamino]propan-1-ol-κ3N,N′,O}copper(II from synchrotron data
Directory of Open Access Journals (Sweden)
Jong Won Shin
2016-10-01
Full Text Available The title compound, [CuCl2(C10H16N2O], has been synthesized and characterized by synchrotron single-crystal X-ray diffraction and FT–IR spectroscopy. The 2-methyl-2-[(pyridin-2-ylmethylamino]propan-1-ol (mpmapOH ligand, including pyridine, amine and hydroxy groups, was synthesized by the reaction of 2-amino-2-methylpropan-1-ol with pyridine-2-carbaldehyde and was characterized by NMR spectroscopy. In its CuII complex, the metal ion has a distorted square-pyramidal coordination geometry with two N and one O atom of the mpmapOH ligand and one chloride anion in the equatorial plane, and the second chloride in an axial position. The bond lengths involving the CuII ion range from 1.9881 (10 to 2.0409 (9 for the Cu—N and Cu—O bonds, and from 2.2448 (5 to 2.5014 (6 Å for the equatorial and axial Cu—Cl bonds, respectively. Intermolecular hydrogen bonds (N—H...Cl and O—H...Cl and face-to-face π–π interactions stabilize the molecular structure and give rise to a two-dimensional supramolecular structure extending parallel to (101.
|
{"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": 0.6719388365745544, "perplexity": 15326.3101538488}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "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-2018-30/segments/1531676589404.50/warc/CC-MAIN-20180716154548-20180716174548-00542.warc.gz"}
|
https://www.atmos-chem-phys.net/19/3065/2019/
|
Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic
Atmos. Chem. Phys., 19, 3065-3095, 2019
https://doi.org/10.5194/acp-19-3065-2019
Atmos. Chem. Phys., 19, 3065-3095, 2019
https://doi.org/10.5194/acp-19-3065-2019
Research article 11 Mar 2019
Research article | 11 Mar 2019
# Transport of Po Valley aerosol pollution to the northwestern Alps – Part 1: Phenomenology
Transport of Po Valley aerosol pollution to the northwestern Alps
Henri Diémoz1, Francesca Barnaba2, Tiziana Magri1, Giordano Pession1, Davide Dionisi2, Sara Pittavino1, Ivan K. F. Tombolato1, Monica Campanelli2, Lara Sofia Della Ceca3, Maxime Hervo4, Luca Di Liberto2, Luca Ferrero5, and Gian Paolo Gobbi2 Henri Diémoz et al.
• 1ARPA Valle d'Aosta, Saint-Christophe, Italy
• 2Institute of Atmospheric Science and Climate, ISAC-CNR, Rome, Italy
• 3Instituto de Física Rosario, Rosario, Argentina
• 4MeteoSwiss, Payerne, Switzerland
• 5GEMMA and POLARIS research centres, Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy
Abstract
Mountainous regions are often considered pristine environments; however they can be affected by pollutants emitted in more populated and industrialised areas, transported by regional winds. Based on experimental evidence, further supported by modelling tools, here we demonstrate and quantify the impact of air masses transported from the Po Valley, a European atmospheric pollution hotspot, to the northwestern Alps. This is achieved through a detailed investigation of the phenomenology of near-range (a few hundred kilometres), trans-regional transport, exploiting synergies of multi-sensor observations mainly focussed on particulate matter. The explored dataset includes vertically resolved data from atmospheric profiling techniques (automated lidar ceilometers, ALCs), vertically integrated aerosol properties from ground (sun photometer) and space, and in situ measurements (PM10 and PM2.5, relevant chemical analyses, and aerosol size distribution). During the frequent advection episodes from the Po basin, all the physical quantities observed by the instrumental setup are found to significantly increase: the scattering ratio from ALC reaches values >30, aerosol optical depth (AOD) triples, surface PM10 reaches concentrations >100µg m−3 even in rural areas, and contributions to PM10 by secondary inorganic compounds such as nitrate, ammonium, and sulfate increase up to 28 %, 8 %, and 17 %, respectively. Results also indicate that the aerosol advected from the Po Valley is hygroscopic, smaller in size, and less light-absorbing compared to the aerosol type locally emitted in the northwestern Italian Alps. In this work, the phenomenon is exemplified through detailed analysis and discussion of three case studies, selected for their clarity and relevance within the wider dataset, the latter being fully exploited in a companion paper quantifying the impact of this phenomenology over the long-term . For the three case studies investigated, a high-resolution numerical weather prediction model (COSMO) and a Lagrangian tool (LAGRANTO) are employed to understand the meteorological mechanisms favouring transport and to demonstrate the Po Valley origin of the air masses. In addition, a chemical transport model (FARM) is used to further support the observations and to partition the contributions of local and non-local sources. Results show that the simulations are important to the understanding of the phenomenon under investigation. However, in quantitative terms, modelled PM10 concentrations are 4–5 times lower than the ones retrieved from the ALC and maxima are anticipated in time by 6–7 h. Underestimated concentrations are likely mainly due to deficiencies in the emission inventory and to water uptake of the advected particles not fully reproduced by FARM, while timing mismatches are likely an effect of suboptimal simulation of up-valley and down-valley winds by COSMO. The advected aerosol is shown to remarkably degrade the air quality of the Alpine region, with potential negative effects on human health, climate, and ecosystems, as well as on the touristic development of the investigated area. The findings of the present study could also help design mitigation strategies at the trans-regional scale in the Po basin and suggest an observation-based approach to evaluate the outcome of their implementation.
1 Introduction
In mountainous regions, mutual exchanges between the valley atmosphere and the nearby plains have been recognised and studied for more than a century (e.g. Thyer1966, and references therein). Notably, daytime up-valley (nighttime down-valley) flows systematically develop as a result of faster heating (cooling) of mountain valleys compared to the foreland , and hence manifest on a very regular basis, especially during fair-weather days (nights) with weak synoptic circulation . The plain-to-mountain circulation regime conveys mass, heat, and moisture within the planetary boundary layer (PBL), thus contributing to horizontal mixing on the mesoscale . Additionally, air parcels can be lifted by convection above the ridges and transported to the free troposphere, which favours air mass exchange in the vertical direction .
Thermally driven wind systems are observed in mountainous regions throughout the world . The European Alps have been the ideal scenario for such kinds of studies, owing to their rugged shape, forming hundreds of main and tributary valleys, and large surrounding plains with strong emission sources, the most significant being in the Po basin. Indeed, this vast region, which includes a large portion of northern Italy, is one of the most densely populated (more than 20 million people and a population density of 414 inhabitants per square kilometre, ), industrialised, and thus polluted areas in Europe . The valley morphology exacerbates the air quality. In fact, heavy emissions from productive activities as well as from vehicular traffic and residential heating are often trapped within the Po basin due to its characteristic topography strongly limiting the dispersion of pollutants, with the Alpine chain and the Apennines enclosing the plain on its northern, western, and southern sides. As a consequence, the Po basin is one of the European hotspots suffering from premature mortality associated with atmospheric pollution (EEA2015). In spite of the improvements in the last decades (e.g. Bigi and Ghermandi2016), the air quality in the Po Valley is still far from the standards established by the European Commission and exceedances of these standards are expected to continue in the next years .
Figure 1(a) Panoramic view of the main valley over the Aosta–Saint-Christophe station during a pollution advection event. The picture was taken from Croce di Fana (2200 m a.s.l., Quart village, 6 km northeast of Aosta–Saint-Christophe) on 21 October 2017. On that day, the advected layer of aerosol – visible in the picture as a hazy layer – reached an altitude of about 2000 m a.s.l. Photo kindly provided by Corrado Cometto. (b) Image of the Po Valley from the MODIS Aqua radiometer (corrected reflectance, true colour) only a few days before the picture in (a) was taken (18 October; https://worldview.earthdata.nasa.gov, last access: 28 February 2019). The satellite view clearly shows that the hazy aerosol-rich layer from the Po basin is starting to pour out into the Alpine valleys. The pink marker identifies the Aosta–Saint-Christophe site.
Both theoretical studies and experimental campaigns demonstrated that transboundary transport of several kinds of pollutants from the Po basin affects pre-Alpine areas , the Italian Alpine valleys , other Italian regions , and even neighbouring countries (e.g. Wotawa et al.2000; Finardi et al.2014). Over the impacted areas, a correct partitioning between local and non-local sources is therefore necessary to (1) correctly interpret the exceedances of air quality limits and (2) develop joint efforts and large-scale mitigation strategies (WMO2012) to reduce the frequency and impact of pollution episodes on citizen health , climate , and ecosystems . As an additional important aspect, in mountainous regions, pollution layers undermine the visual quality of the landscape (e.g. Fig. 1a) and thus touristic attractiveness, with obvious economic implications .
In the present study, we aim at illustrating and deeply investigating the phenomenology of aerosol transport events to the northwestern Alpine region through a detailed analysis and discussion of specifically selected case studies. The impacts of this phenomenon over the long-term will be quantified in a companion paper .
In fact, several previous field campaigns investigated the atmospheric composition and transport mechanisms in the eastern and central part of the Po Valley , but very few studies are available on the westernmost side of the basin . Earlier evidence of possible advection of pollutants from the Po basin to the northwestern Alps was collected in the framework of two intensive 4-day-long campaigns performed between 2000 and 2001 . At that time, an equipped aircraft flew during anticyclonic conditions with weak synoptic circulation in order to assess the effects of the local winds on the air quality in the Alpine valleys close to Mont Blanc (in Italy, France, and Switzerland). The experiment was focussed on ozone measurements and its precursors; however aerosol concentrations were additionally measured. Capping inversions limiting the development of the mixing layer, vertical transport of pollutants along the valley slopes, and the ozone-polluted residual layer aloft (entrained into the mixing layer during the next day) were the most interesting phenomena explored by that study. Advection from the Po Valley with thermally driven flows was hypothesised to be the main factor contributing to the high ozone concentrations found in the elevated layers. Although this result was supported by measurements of carbon monoxide, ambient particulate matter (PM), and relative humidity (RH), the short duration of the campaign could not allow exclusion of other effects. More recently, analysed a 1-year-long time series of columnar aerosol optical properties measured by a sun–sky photometer in the same area and found that the heaviest burden of particles did not come from the largest urban settlement in the Aosta Valley, but rather from outside the region, namely from the Po basin.
The present research exploits a multi-technique approach, combining a large set of measurements with modelling tools in order to answer the following scientific questions still lacking a comprehensive understanding:
1. What is the origin of the aerosol layers detected in the northwestern Alps?
2. What conditions are favourable to the aerosol flow into the valley?
3. How do the advected aerosol layers evolve in both altitude and time?
4. What is the impact of the transported aerosol on PM surface concentrations and chemical composition?
5. Are the current chemical transport models able to reproduce and explain the observations at the ground and along the vertical profile?
Figure 2(a) Elevation map of Italy, showing the position of the investigated Alpine region and the geographical domains of (1) the numerical weather prediction model (COSMO-I2, orange box), (2) the national emission inventory (QualeAria, red box), and (3) the local inventory of the Aosta Valley (blue box). (b) Zoom over the Aosta Valley and northwestern Italy, with location of the measurement stations. The blue box corresponds to the geographic domain of the local inventory as in panel (a). The elevation (colour) scale is the same for both figures.
Though referring to the location object of the study, these questions are of more general interest, as several regions of the world are characterised by basin valleys surrounded by mountains. Hence, the role of pollution advection, their vertical behaviour and the final impact at ground level is a matter of global interest .
The paper is organised as follows: the investigated area is presented in Sect. 2, while Sect. 3 describes both the experimental (Sect. 3.1) and the modelling (Sect. 3.2) approach used. Results (Sect. 4) are presented by addressing specific case studies to exemplify the advection of polluted aerosol-rich air masses and comparing them to the simulations. Conclusions are drawn in Sect. 5.
2 Investigated area and experimental sites
This study is mainly focussed on the Aosta Valley, the smallest Italian administrative region (130 000 inhabitants, Fig. 2). It is about 80 km by 40 km wide and is located on the northwestern side of the Alps, not far from the two major urban settlements and industrial areas of the Po Valley, i.e. Turin (80 km) and Milan (150 km). The region is characterised by a complex topography, typical of the Alpine valleys. Its surface elevation varies from 300 to 4800 m a.s.l. (average altitude >2000m a.s.l.), with several tributary valleys starting from the main valley. The latter connects Mont Blanc (at the border with France, Fig. 2b) to the Piedmont region through a 90 km long directrix, approximately divisible into three segments with NW–SE, W–E, and NW–SE directions. This main valley is narrower at both ends (with a minimum width of a few hundred metres) and widens in correspondence with Aosta city, the largest urban settlement of the region (about 35 000 inhabitants). The complex topography triggers several meteorological phenomena typical of mountain valleys, such as wind channelling along the main valley, thermally driven winds from the plain to the mountains (and vice versa), rain-shadow (foehn) winds, and temperature inversions. The latter are very frequent during wintertime, occurring about 50 % of the time . Not surprisingly, these dynamics strongly affect the dispersion of pollutants and the air quality in the lowest atmospheric layers.
Data from several measuring sites in the Aosta Valley are used in this work (Fig. 2b). Most of the instruments employed (Sect. 3.1) are operated at the two observatories run by the regional environment protection agency (ARPA) in Aosta: Aosta–Saint-Christophe and Aosta–downtown. The Aosta–Saint-Christophe station (WIGOS ID 0-380-5-1, 45.7 N, 7.4 E, 560 m a.s.l.) is located in a large flat area with a wide field of view, at the bottom of the main valley, about 2.5 km east of Aosta–downtown. The site is in a semi-rural context, partially influenced by vehicular traffic and anthropogenic activities from the city, such as domestic heating and industry. The experimental setup at this site includes an automated lidar ceilometer (ALC) for the operational monitoring of the aerosol profile , a POM-02 sun photometer for the retrieval of column aerosol properties and water vapour , and a Fidas 200s optical particle counter (OPC) for the surface aerosol size distribution, in addition to instruments measuring solar radiation and trace gases . Aosta–downtown (580 m a.s.l.) is an urban background site. This station is equipped with samplers for continuous monitoring of atmospheric pollution, mainly coming from car traffic, domestic heating, and a steel mill located south of the city. To provide an idea of the aerosol load in Aosta–downtown, the annual averages of PM10 and PM2.5 concentrations calculated for the last 3 years of measurements (2015–2017) range between 18 and 21 and between 11 and 12 µg m−3, respectively. Despite these low average concentrations, daily PM10 exceedance episodes with maxima of up to about 100 µg m−3 can be observed, their occurrence strongly depending on the encountered meteorological conditions (five exceedance episodes in 2016, 13 in 2015, and 17 in 2017). Thus, there is the need to unravel their behaviour and the role played by regional transport from most polluted areas. Additional measurements used here were performed at the more elevated sites of La Thuile (1640 m a.s.l.), Saint-Denis (840 m a.s.l.), and Antey (1040 m a.s.l.) and at Donnas, a low-altitude site (316 m a.s.l., Fig. 2b) close to the border with the Piedmont region, at the entrance of the Aosta Valley. La Thuile is a remote mountain site in a tributary valley hosting a meteorological and air quality station managed by ARPA. Similarly, a weather station is operated in the village of Saint-Denis by the regional meteorological bureau. Antey is a further small village in a tributary valley where an ARPA mobile laboratory was temporary operated. Finally, the Donnas station is located in a rural area, only partially influenced by traffic and agricultural local activities, such as burning of agricultural residuals. However, due to its proximity to the Po basin, it is expected to be heavily influenced by pollution from the plain.
As the vertical dimension is important in this investigation, we also used measurements from an ALC operating in Milan (Fig. 2), this being representative of the contrasting conditions within the Po Valley. The system is located on the U9-building (45.5 N, 9.2 E, 132 m a.s.l.) of the University of Milano-Bicocca, in an urban background area northeast of the city centre. A full description of the site and measurements is reported in .
3 Methods
## 3.1 Measurements
The experimental setup used in this work includes vertically resolved measurements from ALCs (Sect. 3.1.1), vertically integrated (columnar) aerosol measurements from both ground (Sect. 3.1.2) and space (Sect. 3.1.3), and in situ measurements of aerosol concentration and composition (Sect. 3.1.43.1.5), complemented by ancillary gas-phase pollutants and meteorological measurements (Sect. 3.1.6). Table 1 summarises the instruments used throughout this study at their respective measuring stations.
Table 1Observation sites, measurements, and instruments employed in this study.
a Underwent major maintenance in the second half of 2016 and January 2017. b Available for 4 days every 10 days.
### 3.1.1 Automated lidar ceilometers
Vertical profiles of air constituents are particularly useful in identifying transport of pollutants of non-local origin. However, the profiling capability of the Italian regional environment protection agencies is still scarce. Over the Po basin, continuous monitoring of the atmospheric composition along the vertical profile is lacking and information at different altitudes is mostly available for short periods and during specific dedicated field campaigns .
Light detection and ranging (lidar) instruments permit us to resolve the vertical distribution of particles. The recent technological and data-processing advances , and commercialisation, of simple lidar systems with operational capabilities allow to use this kind of system in monitoring (24∕7) mode and in wide networks. In the present study, we employ two commercially available ALCs (CHM15k-Nimbus, manufactured by Lufft GmbH, and formerly by Jenoptik ESW), which have been operating since 2015 at the Aosta–Saint-Christophe observatory and in Milan. Both ALCs are part of the Italian ALICEnet (http://www.alice-net.eu/, last access: 28 February 2019) and the European E-PROFILE (https://ceilometer.e-profile.eu/profileview, last access: 28 February 2019) networks. They allow for continuous vertical profiling of the radiation emitted by a single-wavelength (1064 nm) pulsed laser (Nd:YAG; 6.5–7 kHz; 8 µJ pulse−1) and backscattered by the atmosphere. At the operating wavelength, the backscatter is mainly dominated by aerosols and clouds in the atmosphere, whereas interference by water vapour has been estimated to be negligible . The systems enable a typical temporal resolution of 15 s (integration time) and a vertical resolution of 15 m, up to 15 km above the ground. The main limitations of the instruments are (1) the need for corrections in the lowermost levels and a (2) blind view above thick clouds. (1) In the lowermost levels, the field of view (0.45 mrad) of the receiver is only partially overlapped with the laser beam (90 % overlap is achieved at about 700 m); therefore, an overlapping correction function is needed to correct the signal. This was provided by the manufacturer. (2) Thick clouds cause saturation in the detector signal (an avalanche photodiode operated in photocounting mode), followed by complete signal extinction. Thus, the attenuated backscatter above the cloud ceiling is not considered (nor plotted) in this study. The ALC firmwares used so far (versions 0.730–0.743 for Aosta–Saint-Christophe and 0.730 for Milan) provide the background-, overlap-, and range-corrected attenuated backscatter (RCS) in terms of instrumental raw counts, i.e.
$\begin{array}{}\text{(1)}& \mathrm{RCS}\left(z,t\right)=\frac{\left(P\left(z,t\right)-B\left(t\right)\right)\phantom{\rule{0.125em}{0ex}}{z}^{\mathrm{2}}}{O\left(z\right)},\end{array}$
where P(z,t) is the signal intensity (raw counts) backscattered from a specific distance (z) and measured at ground, B(t) the time-varying background baseline, and O(z) the overlap function. To express the backscatter coefficient in SI units and make the results comparable with other similar instruments, a calibration factor (CL) must be assessed, so that
$\begin{array}{}\text{(2)}& \frac{\mathrm{RCS}\left(z,t\right)}{{C}_{\mathrm{L}}}={\mathit{\beta }}_{\mathrm{att}}\left(z,t\right)={\mathit{\beta }}_{\mathrm{T}}\left(z,t\right)\phantom{\rule{0.125em}{0ex}}{e}^{-\mathrm{2}{\int }_{{z}_{min}}^{z}{\mathit{\alpha }}_{\mathrm{T}}\left({z}^{\prime },t\right)\mathrm{d}{z}^{\prime }},\end{array}$
where βatt is the attenuated backscatter coefficient, βT is the total (particles and molecules) backscatter coefficient, and αT is the total extinction coefficient. CL is determined during clear-sky time windows of at least 3 h at night, i.e. when the background radiation is low, using the method (Rayleigh technique) described hereafter. First, the backscatter and extinction profiles are calculated with the Klett–Fernald backward algorithm (Fernald1984; Klett1985); then CL is determined by inverting Eq. (2). Once a series of calibration factors has been estimated, the total (αT, βT) and particle (αp, βp) extinction and backscatter coefficients are computed for all times and sky conditions using a forward Klett method as described by .
Usually, the above-mentioned solving techniques are based on an a priori or independent estimate of the lidar ratio (LR, i.e. the ratio αpβp) as a further constraint. In our case, LR is not fixed a priori but rather obtained using specific functional relationships linking αp to βp. demonstrated that this approach, previously proposed and tested on the signal inversion of research-type elastic lidars (e.g. Barnaba and Gobbi2001, 2004), provides better retrievals of αp and βp also from ALCs than using an a priori fixed LR. More specifically, an iterative data inversion scheme is adopted: at the first iteration, LR is set to an initial value of 38 sr (average value from the functional relationships) and a first retrieval of the backscatter coefficient βp is calculated; starting from the second iteration, the calculated backscatter coefficient and the functional relationships are used to determine an altitude-dependent lidar ratio. The loop continues until convergence of the column-integrated backscatter is reached. The good agreement between the ALC-derived and the sun-photometer-measured aerosol optical depth (AOD, i.e. the integral over altitude of the extinction coefficient) is employed as a validation of the quality of the inversion results (Sect. 4.1.4 and 4.3.5) using these functional relationships, at least in daytime conditions (see also , and Figs. S2d and S9e in the Supplement).
For ease of comparison with pristine (aerosol-free) conditions, and with most lidar-based studies, ALC measurements are provided in this study in terms of scattering ratio (SR, e.g. Zuev et al.2017), i.e.
$\begin{array}{}\text{(3)}& \mathrm{SR}=\frac{{\mathit{\beta }}_{\mathrm{T}}}{{\mathit{\beta }}_{\mathrm{m}}}=\frac{{\mathit{\beta }}_{\mathrm{p}}+{\mathit{\beta }}_{\mathrm{m}}}{{\mathit{\beta }}_{\mathrm{m}}},\end{array}$
where βm is the molecular backscatter coefficient. In the case of pure molecular scattering (no aerosol in the atmosphere), SR=1, while SR increases with increasing aerosol load. Finally, the high-resolution data from the ALC are downscaled to 75 m averages over the vertical and 5 min averages over time to increase the signal-to-noise ratio. A first example of the output from the Aosta–Saint-Christophe ALC, in terms of scattering ratio, can be found in Fig. 3a. This image refers to a typical sequence of days (August 2015), characterised by a recurrent increase in the particle backscatter during the afternoon, up to an altitude of more than 2000–3000 m a.s.l. (the altitude of the surface being 560 m a.s.l. in Aosta–Saint-Christophe). As we will demonstrate here, this afternoon increase is due to the coupled effect of transport of polluted air masses from the Po basin and aerosol hygroscopic growth (see Sect. 4). Several analogous episodes were recorded in the ALC record since its installation in Aosta–Saint-Christophe. The observation of this recurrent phenomenon was, in fact, the driving motivation for the present research.
In the study, we also convert the ALC-derived backscatter into aerosol volume following , thus allowing a direct comparison to more standard air quality metrics (e.g. PM10; this is carried out using a particle density ρ=1.3g cm−3 independently estimated for the present study by an OPC co-located with the ALC). The expected uncertainties in the retrieval of the aerosol backscatter and extinction coefficients and of the aerosol volume range between 30 % and 40 % .
### 3.1.2 Sun photometer
A POM-02 sun–sky radiometer has operated at the Aosta–Saint-Christophe observatory since 2012. The radiometer is part of the European ESR-SKYNET network (http://www.euroskyrad.net/, last access: 28 February 2019). The irradiances collected by the POM-02 at 11 wavelengths (315–2200 nm) are inverted to retrieve the aerosol optical properties using both the direct sun (SUNRAD.pack algorithm to provide the AOD every 1 min, ) and the almucantar geometries (SKYRAD.pack software version 4.2 to retrieve a complete set of optical and microphysical columnar properties every 10 min, ). The instrument is calibrated in situ with the improved Langley technique, described by in more detail, and was successfully compared to other reference instruments during a recent international campaign . The AOD (τ) from the POM-02 is interpolated to the ALC wavelength (1064 nm) using the relationship, i.e.
$\begin{array}{}\text{(4)}& \mathit{\tau }=b\phantom{\rule{0.125em}{0ex}}{\mathit{\lambda }}^{-a},\end{array}$
where λ is the wavelength expressed in micrometres and a and b are the Ångström parameters from the regression. Finally, the Cloud Screening of Sky Radiometer data (CSSR) algorithm by , making use of the short-wave irradiance measurements by a co-located pyranometer, is applied to the POM-02 series to minimise the residual interference by clouds and to ensure the maximum measurement quality.
### 3.1.3 Space-based observations from MODIS
In this study, we also used satellite data to explore if and how the “local” phenomenon observed in Aosta is detectable over a regional scale. To this purpose, we used AOD data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. The MODIS instrument flies on board the two NASA platforms Terra and Aqua, following a sun-synchronous orbit with overpass times between 10:00 and 13:00 and 13:00 and 16:00 (local time), respectively. Since the MODIS instrument planning phase, specific retrievals have been set up to provide the AOD over ocean and land globally on a daily basis at 10 km resolution . Constant improvements to the AOD inversion algorithms resulted in a 3 km resolved standard AOD product . While such spatial resolutions have been extensively exploited for many regional-scale, aerosol-related studies, these are yet not sufficient for applications requiring more spatial detail, as in space-based evaluations of air quality within urban areas or in conditions of high AOD spatial variability as over mountain regions (e.g. Emili et al.2011). For our purpose, we therefore used high-resolution (1 km) AOD data obtained inverting MODIS data with the recently developed algorithm MAIAC (Multi-Angle Implementation of Atmospheric Correction). Full details of this algorithm are thoroughly described in .
### 3.1.4 Optical particle counter
A Fidas® 200s OPC operates at the ARPA observatory in Aosta–Saint-Christophe. The spectrometer is based on the analysis of scattered light at 90 originating from a polychromatic light source (LED). These conditions ensure an accurate calibration curve without ambiguities within the Mie range and allow us to retrieve high-resolution spectra (size measurements between 0.18 and 18 µm, 32 channels decade−1). Due to the peculiar T-aperture optics of the spectrometer and the simultaneous measurement of signal duration, border zone errors are eliminated. Once the particle size distribution is measured, the instrument algorithm is able to derive the mass concentration for several cutoff diameters (including PM10, i.e. ambient particulate with a diameter of 10 µm or less). Though not a direct mass measurement, the PM concentration derived by the instrument obtained the certificate of equivalence to the gravimetric method by TÜV Rheinland Energy GmbH on the basis of a laboratory test and a field test. Moreover, to prevent any site-specific bias, an additional PM10 comparison with the gravimetric technique was organised at Aosta–Saint-Christophe and provided satisfactory results (29 days; slope 1.08±0.04; intercept $-\mathrm{3.8}±\mathrm{1.4}$µg m−3; R2=0.96).
### 3.1.5 PM concentration and composition
Daily averages of PM concentration are recorded by four Opsis SM200 particulate monitor instruments, two in Aosta–downtown (PM10 and PM2.5 inlets, with sampling fluxes of 1 and 2.3 m3 h−1, respectively), one installed inside a mobile laboratory, which was parked in Antey (PM10, 1 m3 h−1), and one in Donnas (PM10, 1 m3 h−1). Moreover, two tapered element oscillating microbalance (TEOM) 1400a monitors are used for continuous measurements of PM10 hourly concentrations at the stations of Aosta–downtown and La Thuile. These instruments do not compensate for mass loss of semi-volatile compounds and could be insensitive to specific compounds, such as ammonium nitrate (e.g. Charron et al.2004), which leads to underestimations, especially in the cold season, compared to the SM200. Conversely, overestimations by the TEOM compared to daily averages from the SM200 reference instrument are found in summer and are not fully understood at present. Therefore, TEOM monitors are only employed here for qualitative estimates of short-term variations in the aerosol burden while daily-averaged concentrations will only be taken from the SM200 instruments.
Sampling in Aosta–downtown is complemented with chemical speciation analyses. We employed a Dionex ion chromatography system (AQUION/ICS-1000 modules) for water-soluble anion–cation chemical analyses on daily PM10 samples collected on PTFE-coated glass fiber filters by the Opsis SM200. The experimental setup is based on the CEN/TR 16269:2011 guideline and enables the determination of mass concentrations of the following water-soluble ionic compounds: Cl, ${\mathrm{NO}}_{\mathrm{3}}^{-}$, ${\mathrm{SO}}_{\mathrm{4}}^{\mathrm{2}-}$, Na+, ${\mathrm{NH}}_{\mathrm{4}}^{+}$, K+, Mg2+, and Ca2+. Samples collected on quartz fibre filters by a co-located Micro-PNS automatic low-volume sampling system (10 µm cutoff diameter, 2.3 m3 h−1) are analysed alternatively for elementalorganic carbon (EC∕OC, 4∕10 days) and for metals (6∕10 days; not used in the present study, but discussed by ). The carbonaceous aerosol mass is determined with a Sunset Laboratory Inc. instrument on portions of 1 cm2 punches using a thermal–optical transmission (TOT) method with transmission correction for the split point and following the EUSAAR-2 protocol , according to the EN 16909:2017.
### 3.1.6 Gas-phase pollutants and meteorological ancillary data
Standard gas-phase pollutants subject to European regulations are routinely monitored at Aosta–downtown, La Thuile, and Donnas in the frame of the activities of the air quality network. Meteorological parameters, such as temperature, pressure, RH, and surface wind velocity are collected at the stations of Aosta–Saint-Christophe, Saint-Denis, and Donnas. Moreover, 10 temperature and RH sensors (Hobo H8 Pro) are installed along the north-facing mountain slope south of Aosta, at elevations ranging from 550 to 1200 m a.s.l. This set of measurements, representing a vertical profile of surface temperature and RH, gives useful information about the thermal inversions in the main valley. For example, pseudo-equivalent potential temperatures (e.g. Freney et al.2011) at different altitudes can be easily calculated from this dataset, thus providing a rough indication of the vertical extent of the mixed layer (Sect. 4.2.2).
## 3.2 Models
Models are used to interpret and complement the observations. A numerical weather prediction (NWP) model (COSMO, Consortium for Small-scale Modeling, http://www.cosmo-model.org, last access: 28 February 2019; Sect. 3.2.1) is employed to drive a chemical transport model (FARM, Flexible Air quality Regional Model; Sect. 3.2.2) and a Lagrangian model (LAGRANTO) to retrieve the trajectories of air masses arriving at the experimental site (Sect. 3.2.3).
### 3.2.1 Numerical weather prediction model
COSMO is a non-hydrostatic, fully compressible atmospheric prediction model working on the meso-β and meso-γ scales. A detailed description of the model can be found elsewhere (e.g. ). The COSMO data are operationally disseminated by the meteorological operative centre – air force meteorological service (COMET) in two different configurations: a lower-resolution (7 km horizontal grid and 45-level vertical grid, 72 h integration) version (COSMO-ME), covering central and southern Europe, and a nudged, higher-resolution version (2.8 km, 65 vertical levels, 2 runs day−1), called COSMO-I2 (or COSMO-IT), covering Italy (Fig. 2). Owing to the complex topography of the Aosta Valley and the consequent need to resolve the atmospheric circulation at very small spatial scales, the COSMO-I2 variant is employed in this work.
As an example of the good agreement between COSMO and surface measurements, the average daily cycle of the wind speed and direction from both data sources is exhibited in Fig. S1 in the Supplement. The figure clearly shows the regular development of the plain–mountain winds in the afternoon. The influence of the east–west directrix of the main valley along which the wind is channelled is well represented in both measurements and simulations.
### 3.2.2 Chemical transport model
FARM is a three-dimensional Eulerian model for simulating the transport, chemical conversion, and deposition of atmospheric pollutants. The FARM source code has been inherited from the Sulfur Transport and dEposition Model (STEM), extensively tested and used since the 1980s. FARM can be easily interfaced to most available diagnostic or prognostic NWP models. A turbulence and deposition pre-processor (SURFace-atmosphere interface PROcessor, SURFPRO) computes the 3-D fields of turbulence scaling parameters, eddy diffusivities, and deposition velocities for each species based on an input gridded land-use field and the results of the NWP model . Pollutant emissions from both area and point sources can be simulated by FARM including plume rise calculations. Transformation of chemical species by gas-phase chemistry (more than 200 reactions using the SAPRC-99 chemical scheme as in ), dry removal of pollutants depending on local meteorology and land-use, and wet removal are considered. The AERO3_NEW module, coupled with the gas-phase chemical model and treating primary and secondary particle dynamics and their interactions with gas-phase species, is implemented for the calculation of the aerosol concentration fields, thus accounting for nucleation, condensational growth, and coagulation . The aerosol size distribution is parametrised using three modes simulated independently: the Aitken mode (D<0.1µm), the accumulation mode (0.1 µm$µm), and the coarse mode (D>2.5µm). PM2.5 is defined as the sum of Aitken and accumulation modes, while PM10 is given by the sum of the three modes. Chemical speciation is performed in the pre-processing phase by the emission manager (EMMA) based on the profiles from the U.S. EPA model SPECIATE (v3.2, 2002; see https://www.epa.gov/air-emissions-modeling/speciate-version-45-through-40 for more recent versions, last access: 28 February 2019). To simulate hygroscopic growth by aerosols in high-RH conditions, water uptake by aerosol particles is taken into account based on the ISORROPIA model and added to the PM10 dry mass concentration from FARM. The resulting output species is called PM10w in FARM version 4.7.
The FARM output concentrations are 4-D fields at 1 km spatial resolution along the horizontal dimensions, 16 different vertical levels (from the surface to 9290 m, corresponding to equally spaced pressure levels), and 1 h temporal resolution. The PM10w concentration profiles from FARM are extracted at the grid cell corresponding to Aosta–Saint-Christophe for comparison with the profiles measured by the ALC. Indeed, since FARM is not able to calculate the aerosol optical properties needed to simulate the backscatter coefficient measured by the ALC, the comparison between the profiles measured by the ALC and estimated by the chemical transport model (CTM) is performed here in terms of mass concentration (by converting the ALC data into PM10; see Sect. 3.1.1).
Supplying a detailed and precise emission inventory to the CTM is crucial to accurately assess the magnitude of the pollutant loads and their variability in both time and space. Additional information regarding the regional emission inventory and the boundary conditions is provided in the Supplement (Sects. S2–S3). The geographic coverage of the regional and the national emission inventories is shown in Fig. 2. Local sources and boundary conditions can be switched on or off for sensitivity analyses.
### 3.2.3 Back trajectories
The publicly available LAGRANTO Lagrangian analysis tool, version 2.0 , is used to numerically integrate the high-resolution 3-D wind fields from COSMO and to determine the origin of the air masses sampled by the ALC over Aosta–Saint-Christophe. The software also enables to trace 3-D and 2-D meteorological fields along each trajectory. In particular, the algorithm was set up to start eight trajectories in a circle of 1 km around the observing site and at seven different altitudes from the ground to 4000 m a.s.l., for a total of 56 trajectories for every run. From a 1-year (2016) analysis of the trajectories arriving to the Aosta Valley, it is found that a backward run time of 48 h is sufficient, on average, to cover most of the domain of the meteorological model. Therefore, we limit the computation to this duration.
4 Results
The observed phenomenon is presented through three case studies (August 2015, January 2017, May 2017), chosen for their relevance and clarity. The episodes are also representative of three different atmospheric conditions (seasons) and were observed with slightly different sets of operating instruments (Table 1). The case studies were also selected among those showing long sequences of days characterised by the recurrent appearance of a thick aerosol layer from the ALC, to emphasise the periodicity of the phenomenon. Indeed, as explained in more detail by , the elevated aerosol layer can be observed very frequently, i.e. about 50 % of the days, depending on the season.
## 4.1 Case study 1: summer (August 2015)
One of the longest and most notable episodes of unexpected high aerosol loads in the northwestern Alps was registered from 26 August to 3 September 2015, a few months after the ALC installation in Aosta–Saint-Christophe (here we focus on the period 25–31 August, allowing us to show the typical clear conditions before the arrival of the polluted air mass). In those days, a wide anticyclonic area extended from northern Africa to central and eastern Europe. The period is thus representative of fair weather conditions, with only a few cirrus clouds on days 27 and 28 and the absence of strong synoptic flows at ground level, which favoured the regular development of thermally driven winds from the plain to the mountains triggered by temperature and pressure gradients between the valley and the foreground.
Figure 3Case study of 25–31 August 2015. (a) Coloured background: vertical profile of scattering ratio from ALC in Aosta–Saint-Christophe. The signal above the clouds is plotted as white areas. Arrows: horizontal velocity of the wind measured at the surface (bold, lower arrows) and simulated by COSMO at several elevations (thin arrows). Calm wind (speed <1m s−1) is not plotted. A reference arrow for a 10 m s−1 wind blowing from the south to the north is drawn at the bottom right corner. (b) Vertical profile of relative humidity forecasted by COSMO. (c) Vertical profile of PM10 mass concentration derived from ALC. (d) Mass concentration (PM10w) from FARM. PM concentration from non-local sources is represented by the coloured background (the colour scale is chosen to better show the daily pattern simulated by the model) and the effect of local sources by the contour line, at logarithmic steps (dotted: 0.1 µg m−3; dashed, near the surface: 1 µg m−3). (e) Hourly PM10 (dry) surface concentration from FARM simulations in Aosta–Saint-Christophe and observations in Aosta–downtown, for the purpose of checking if any sudden variation in surface air quality data is noticeable.
### 4.1.1 ALC observations
A thick aerosol layer is detected by the ALC over the Aosta–Saint-Christophe observatory from the afternoon of 26 August (Fig. 3a). Very clear conditions are visible in the low troposphere on 25 August, while the high-altitude layer in the morning of the same day, which is not considered here, is due to smoke transport from North America. The appearance of the PBL layer is clearly noticeable on 26 August as an increase in the backscatter coefficient up to an altitude of 3 km a.s.l., with scattering ratios SR ≃4 at midday (light blue area in the figure) almost doubling (SR >8, orange yellow) in a few hours. This layer persists during the night, when the SR reaches values above 30. On 27 August, the ALC backscatter is then observed to decrease in the central part of the day and to increase again in the afternoon. This behaviour stays very regular for almost a week, with the aerosol-rich layer extending from the ground up to 3–3.5 km. As further discussed in the next paragraphs, we anticipate here that the main factor driving this cycle is likely an enhanced hygroscopic growth of aerosol advected from the Po Valley from the afternoon to the early morning, with this effect also leading to the formation of low clouds within the aerosol layer at night (screened out as white areas in the figure). In fact, the transition from aerosol to the cloud phase is very sharp, as also noticeable from the sudden increase of more than 40 W m−2 in the downward infrared irradiance monitored at the same site (Fig. S2c).
Figure 4Vertical profile of scattering ratio from the ALC in Milan. Arrows: horizontal velocity of the wind measured at the surface (bold, lower arrows) and simulated by COSMO at several elevations (thin arrows).
Simultaneous ALC measurements in the city of Milan (see relative position in Fig. 2), which can be considered representative of the overall dynamics occurring within the Po basin, are shown in Fig. 4. An interesting feature here is that the modulation of the scattering ratio looks almost reversed compared to the Aosta–Saint-Christophe site, with a maximum SR at the surface at midday and minimum values during the night and the morning. While in the uppermost levels (>3000 m a.s.l.) the synoptic circulation is blowing undisturbed from the west, the wind velocity at 500 m a.s.l. keeps alternating, likely driven by the breeze regime (the surface wind is affected by urban effects and does not show appreciable variations).
### 4.1.2 Meteorological variables and back trajectories
The observed reversal behaviour in Milan and Aosta already suggests that air mass movements are driving the clean-up of the lowermost levels in the Po plain and the transport of the aerosol plumes elsewhere. To substantiate this hypothesis, a careful analysis of the meteorological fields (observed and modelled) was performed. In particular, we verified that this selected sequence of days presents a typical pattern of plain-to-mountain wind systems during the afternoon of each day in Aosta–Saint-Christophe. Surface-level eastern wind speeds as high as 8 m s−1 are measured daily in the afternoon till sunset and are shown as bold arrows in the lowermost levels of Fig. 3a. Conversely, calm wind is detected during the night, i.e. when the aerosol layer thickens. Since no instrument is available at the measuring site to determine the vertical profile of the wind velocity, the simulations from the COSMO model are used to assess the wind field at several altitudes (thin arrows in Fig. 3a). It reproduces the thermal wind circulation in the lowest atmospheric layers well during the afternoon and slightly overestimates the mountain-to-plain drainage winds at night and early morning (this issue is discussed in Sect. 4.4). The thermally driven wind pattern forecasted by COSMO extends up to an altitude of 3000 m, i.e. approximately the maximum height of the aerosol layer observed by the ALC (reasons for possible discrepancies of this simulated and measured altitude are discussed in Sect. 4.4). Note that wind direction is incompatible with Aosta being the potential source of the observed aerosol layer, as the city is located west of the observatory. At higher elevations, the wind field is clearly decoupled from that in the PBL and follows the large-scale circulation.
Figure 5The 48 h back trajectories ending at Aosta–Saint-Christophe on 26 August 2015 at 18:00 UTC at altitudes lower than 2000 m a.s.l. (a) and higher than 2500 m a.s.l. (b). The trajectories are cut at the border of the COSMO model. The colour scale represents the back-trajectory arrival height. Corresponding altitudes of the back trajectories vs. time are reported in the bottom panels. The dots along each trajectory mark a 1 h step and the black star indicates the trajectory arrival point (Aosta–Saint-Christophe). A more complete sequence for the episode is shown in Fig. S3.
Complementary information is provided by the analysis of the 48 h back trajectories calculated by LAGRANTO using COSMO fields (Sect. 3.2.3) ending over the Aosta Valley in the period addressed (Figs. 5 and S3). For ease of clarity, the LAGRANTO output is shown in separate panels depending on the arrival altitude of each trajectory (<2000 and >2500m a.s.l.). These results show that before the episode (25 August and morning of 26 August, Fig. S3a and d) trajectories are driven by large-scale flows from the west and are thus parallel at all altitudes. Therefore, air masses reached Aosta after crossing the Alps, notably the Mont Blanc chain, hence transporting clear and unpolluted air from the free troposphere to the PBL. Then, in the afternoon of 26 August, back trajectories in the PBL change their provenance owing to the development of the thermal circulation tapping into air masses of very different origin (Fig. 5a), while higher-altitude trajectories mostly continue to follow the synoptic circulation (Fig. 5b). The lowermost trajectories cover a notable distance and cross some major conurbations of the Po basin, i.e. Milan and Turin, at altitudes lower than a few hundred metres above sea level, and thus well within the polluted PBL. This sudden reversal of the trajectories occurs simultaneously with the appearance of the elevated aerosol layers in the Aosta ALC image (Fig. 3a). These meteorological conditions persist for the rest of the day and in the following days. The analysis of the corresponding back trajectories confirms that transport of polluted air masses from the Po basin also occurs in the afternoons of the other days of this episode, until the flux changes again to a northwestern configuration (Fig. S3c and f).
To complete the picture, it is worth mentioning that the COSMO model also predicts an increase in the RH (Fig. 3b) from evening to early morning, almost simultaneous with the SR enhancement observed by the ALC. In this time frame, RH exceeds typical summertime deliquescence values reported for the Po basin in previous studies (e.g. DRH =67 %, D'Angelo et al.2016) and reaches up to 98 % at the ground (Fig. S2b). This suggests hygroscopic growth on aerosols and a consequent increase in the ALC βp. For example, at a measurement site representative of Po Valley conditions, found a median increase in the aerosol backscatter coefficient of 70 % for RH =90 % compared to the dry case. During the day, RH decreases below typical crystallisation values in summer (e.g. CRH =62 %, D'Angelo et al.2016). As RH is clearly modulated by the temperature daily cycle, the measured specific humidity (SH) is also plotted on the same figure (Fig. S2b) as an additional variable independent of temperature, to identify potential advection of different air masses to the observation site. Indeed, a SH increase occurs on 26 August (starting from minimum values of ∼8g kg−1 in the morning to about 11 g kg−1 in the evening) as soon as the wind starts blowing and high values (>13g kg−1) endure for the rest of the week. This likely indicates that the dry air, typical of the more mixed mountain PBL , is replaced by more stagnating, and humidified, air masses characteristic of hot summer days in the Po Valley . This scenario is compatible with recent findings by , who performed water vapour measurements with the POM-02 at Aosta–Saint-Christophe and found that moist air masses mainly come from the east. A discussion about the constancy of the measured SH during each day compared to the more variable values forecasted by COSMO is provided in Sect. 4.4. We anticipate here that this behaviour confirms that COSMO overestimates the nighttime drainage winds (characterised by lower SH) and contributes to the observed discrepancies between the PM concentrations from FARM and the ALC.
### 4.1.3 Mass concentrations
We also show in Fig. 3c the altitude-resolved aerosol mass derived from the ALC backscatter coefficient (as described in Sect. 3.1.1). The maximum concentration within the aerosol layer is >80µg m−3. The corresponding PM10w profile from FARM, partitioned between the non-local (coloured background) and local (contour line) pollution, is shown in Fig. 3d. FARM qualitatively reproduces the recurrent increase in the aerosol concentration at the end of each day and mainly ascribes it to particles transported by the thermal winds from the model-box boundaries. As an example, Fig. 6 provides a 3-D snapshot of the model simulation results, clearly showing the entrance of the aerosol-rich air mass from the Po basin to the Aosta Valley. The picture refers to 28 August 2015 at 15:00 UTC – the whole sequence of 26–31 August 2015 is available as a video file in the Supplement (https://doi.org/10.5446/38391). Still, there are two important differences between the FARM model simulations and the ALC observations in terms of (1) absolute PM10w concentrations and (2) timing of the phenomenon. In fact,
1. PM10w values from FARM are much lower than the ones retrieved from the ALC (about −40 % outside the thick aerosol layer identified by the ALC at night and even −80 % inside the layer);
2. the maximum PM10w simulated concentration during the advection is anticipated by several hours (up to 6–7 h, in the worst cases) compared to the ALC measurements, which, in contrast, show a better correlation with the RH profile by COSMO.
Possible reasons, such as hygroscopicity effects and modelling deficiencies, explaining the above-mentioned issues are further discussed in Sect. 4.4.
Figure 6Still frame of the three-dimensional simulation of PM10 concentration by FARM (image from 28 August 2015 at 15:00 UTC). The image clearly shows the entrance of the aerosol-rich air mass from the Po basin into the Aosta Valley (yellow–blue area). The same colour scale as in Figs. 3d, 9d, and 12d is used (the lowest concentrations are removed for ease of representation). The sequence on 26–31 August 2015 is available as a video file in the Supplement (https://doi.org/10.5446/38391).
Figure 7Measured (coloured bars) and simulated (dotted line) daily averages of PM2.5 and PM10 concentrations at Aosta–downtown and Donnas during case study 1 (August 2015). The period when the ALC detects a thick layer above Aosta–Saint-Christophe is highlighted with a grey background. PM2.5 measurements in Aosta are missing for 2 September 2015.
To evaluate the impacts on surface air quality parameters during the episode, hourly PM10 concentrations at the surface as measured in Aosta–downtown and simulated by FARM in Aosta–Saint-Christophe are presented in Fig. 3e (PM10 monitoring at La Thuile was not yet operational at that time). Apart from two spikes (80 µg m−3) on 25 and 26 August (presumably of local origin), the concentrations measured in Aosta–downtown by the TEOM show a slight increase after the arrival of the layer, but without sudden jumps. Also, PM concentrations are generally higher during daytime compared to the night, according to the expected cycle of the summertime local sources (e.g. traffic, resuspension). These features, however, can be connected to the fact that mass loss occurs in TEOM due to secondary aerosol volatility, as better discussed in the companion paper by comparing the daily PM10 cycle from this instrument and the Fidas OPC in Aosta–Saint-Christophe. Moreover, this volatility could be different between nighttime and daytime, which would also contribute to the observed daily behaviour. In addition, FARM estimates at the surface are again lower than measurements (−60 %, on average). Daily PM10 concentrations observed with Opsis SM200 instruments during the case study in Aosta–downtown and Donnas are shown in Fig. 7, which includes the whole episode (correlation index with TEOM measurements ρ=0.84). The shaded area corresponds to those dates affected by the thick layers as revealed by the ALC. An increase in daily concentrations (up to maximum values of 10 µg m−3 for PM2.5 and 16–22 µg m−3 for PM10) can be clearly noticed at both sites, leading to concentrations slightly higher than average for the same period (7 µg m−3 for PM2.5 in Aosta–downtown and 12 µg m−3 for PM10 at both sites, considering the 2015–2017 series). The statistical significance of such PM increases during these transport episodes, compared to the natural variability in the aerosol load in non-advection conditions, is assessed in the companion paper using the full dataset. The daily averages of the simulated aerosol concentrations at the surface are superimposed on the same figure (dashed lines). While the model qualitatively reproduces the average load of PM2.5 and its variations in Aosta–downtown, it underestimates PM10 at both stations as already noticed.
### 4.1.4 Sun photometer measurements
Since sun photometric measurements only can be performed in daylight, results are often unavailable at those times when the ALC shows the greatest backscatter signal, i.e. in the evening and at night. However, data collected by the POM-02 radiometer can still be effective to monitor the first (late afternoon) and last (early morning) dynamics of the aerosol layer as seen by the ALC (Fig. 3a), and particularly tell us if this signal is detectable in the sun-photometer-derived, column-integrated aerosol load. AOD obtained from the sun photometer (Fig. S2d) varies from 0.02 (25 and 26 August before appearance of the layer) to 0.07 (29 August, morning) at 1064 nm (approximately 0.05 to 0.2 at 500 nm) and closely follows the AOD obtained by vertically integrating the extinction coefficient from the ALC over the atmospheric column. The two independent AOD retrievals present a mean bias of −0.007 and standard deviation of the differences of 0.006, both lower than the declared uncertainty of the POM sun photometer itself (about 0.01) . The good closure with the AOD from the photometer demonstrates the reliability of the functional relationships derived by and employed in our ALC inversion algorithm, at least during the daytime.
Further retrieval products from SUNRAD.pack and SKYRAD.pack (displayed in Fig. S2e) show the Ångström exponent to increase from 1.2 to 1.7 on 26 August from 08:00 to 17:00 UTC, suggesting the advection of smaller particles in the atmosphere, and to remain almost constant (about 1.6, a typical value for the Po Valley, as already described by , and ) in the following days. These values should be compared to the lower Ångström exponents typically measured in the Aosta Valley, i.e. ∼1.1 on average . Likewise, the single-scattering albedo (SSA) at 500 nm increases (from 0.7 to 0.95) on 26 August, which is compatible with the arrival of more scattering (likely secondary aerosol, as described in Sect. 4.2.4 and 4.3.4) and/or more aged aerosol, such as that from the Po Valley . The sun-photometer-derived total-column aerosol volume distribution (Fig. S2f) peaks in the accumulation mode (about 0.3 µm). A slight decrease in the peak diameter in the morning (from about 0.4 to 0.2 µm) can be noticed on some days (e.g. 27–30 August) and might be ascribed to the dehydration of the particles as temperature increases and RH decreases. The same behaviour can be observed better in the third case study (Sect. 4.3.5 and Fig. S9g).
### 4.1.5 Spatial extent of the observed phenomenon
In order to provide a first evaluation of whether the phenomenon observed and described in detail for the Aosta area could have a more general validity in the Alpine region, we used AOD data retrieved from space over northern Italy. In particular, we exploited the high-resolution capabilities of the MODIS–MAIAC AOD product (Sect. 3.1.3) and the availability of two MODIS overpasses during the day (Terra and Aqua platforms), to detect signs of the described effects at the regional scale. Figure 8a shows the average difference between the AOD retrieved each day from MODIS Aqua (overpass time between 12:00 and 13:00 UTC) and that from MODIS Terra (10:00–11:0 UTC). Despite the short time lag between the Terra (AM) and Aqua (PM) satellite overpasses, this figure shows that the data are sufficient to start detecting an overall reduction of the AOD in the Po basin (blue area) and a reverse increase in the mountain areas (Alps and Apennines) surrounding it. The general picture suggests a sort of aerosol drainage from the Po Valley (negative AOD difference, blue) to the Alps (positive AOD difference, red), although some aerosol dehydration from the morning to the afternoon could also partially contribute to the observed morning and afternoon differences. This provides an observation-based confirmation of the hypothesis of aerosol transport, in agreement with our previous results from FARM (e.g. Fig. 6 and the relative video file), and with wind simulations from COSMO over the same area (averaged over the same hours between Terra and Aqua overpasses, Fig. 8b). Valley–mountain (and sea–land) breezes are clearly reproduced, as expected on days with weak synoptic flows and strong heating by the sun.
Figure 8(a) Average difference between AOD estimated from Aqua and Terra satellites during 27–31 August 2015 using the MAIAC algorithm. (b) Horizontal wind velocity from COSMO (arrows); vertical velocity (red and blue contours, ±0.1ms−1) over the same domain and the same hours as in (a).
## 4.2 Case study 2: winter (January 2017)
A second pollution transport episode was chosen for its significance and its consequences on air quality. Indeed, the last days of January 2017 and the first ones of February 2017 were characterised by heavy exceedances of PM10 in the whole Po basin with concentrations of nearly 300 µg m−3 in some stations of northern Italy . This situation was driven by conditions of strong atmospheric stability, weak winds, low mixing height, and presence of clouds and additionally worsened by the transit of a warmer air mass aloft, i.e. the typical circumstances causing the most severe air pollution episodes in the Po basin in winter . Chemical analyses accomplished in the framework of the air quality monitoring network in northern Italy identified considerable formation of secondary particulate (e.g. ammonium nitrate), also confirmed by very large PM2.5∕PM10 ratios (almost 0.9).
In the Aosta Valley, this pollution episode lasted only from 26 to 29 January. At that time, the Alps were contended by a pressure trough at the north and a ridge at the south. At the beginning of the period, the influence of the low-pressure system prevailed and brought cloudy skies over the valley. Although local emissions (e.g. residential heating and traffic, additionally worsened by the temperature inversion) might have also increased in this period, the influence of pollution transport from the Po basin is unambiguous. As a result of the advection, the PM concentrations measured in the Aosta Valley were found to be significant in the whole region (e.g. PM10>100µg m−3 in Aosta–downtown and Donnas), even at some remote measuring sites (e.g. PM10∼70µg m−3 in Antey, Sect. 4.2.3), and remarkably higher than the average concentrations in the same period (e.g. 33 µg m−3 for PM10 and 23 µg m−3 for PM2.5 in Aosta–downtown in 2015–2017). No sun photometric measurements were available for this period due to clouds and major maintenance to the POM-02 instrument.
Figure 9Case study of 24–30 January 2017. (a) Coloured background: vertical profile of scattering ratio from ALC in Aosta–Saint-Christophe. Arrows: horizontal velocity of the wind measured at the surface and simulated by COSMO at several elevations. (b) Vertical profile of relative humidity forecasted by COSMO. (c) Vertical profile of PM10 mass concentration derived from the ALC using the functional relationships. (d) Mass concentration (PM10w) from FARM. (e) Hourly and sub-hourly PM10 (dry) surface concentration from FARM simulations and observations in Aosta–Saint-Christophe, Aosta–downtown, and La Thuile (the y scale of this panel is extended compared to Figs. 3 and 12).
### 4.2.1 ALC observations
The profiles from the ALC in Aosta–Saint-Christophe for this winter case are depicted in Fig. 9a and show the sudden appearance of a thick aerosol layer in the afternoon of 26 January. Unlike the previous case, the ALC measurements do not reveal distinct features for each day of the sequence, but rather a continuous and persisting layer during the whole episode. The SR reaches values above 30 in the night between 26 and 27 at altitude, and, closer to the surface, between the evening of 27 and the morning of 29 January. The layer extends up to 2000 m a.s.l., a clear signature of the non-local origin of the air mass. Some clouds are visible above and within the aerosol layer. The episode ends on 29 January as quickly as it began, with clearer air taking the place of the polluted air mass starting from above and subsequently eroding the layer down to the surface.
Simultaneous ALC profiles over Milan are depicted in Fig. 10. As opposed to the Aosta Valley, the aerosol layer does not vanish on 29 January, but remains for a few days longer, although the winds at altitude change their provenance from the west on that day. Clouds only form from 27 January, presumably allowing solar radiation to trigger a weak breeze tide in the lowest 2000 m on that day, whilst strong stability favours calm wind in the following days.
Figure 10Vertical profile of scattering ratio from the ALC in Milan (24–30 January 2017). Arrows: horizontal velocity of the wind measured at the surface (bold, lower arrows) and simulated by COSMO at several elevations (thin arrows).
### 4.2.2 Meteorological variables and back trajectories
The wind field over Aosta–Saint-Christophe, depicted in Fig. 9a, presents a very different pattern compared to the first case addressed (Fig. 3a). Firstly, calm wind is measured for the whole period at the bottom of the valley. This is due to a shallow temperature inversion in the lower atmospheric layers in the main valley. Conversely, at the Saint-Denis station, located above the inversion layer, and at the Donnas station, where the temperature inversion is weaker, the wind pattern is more representative of the wider circulation: for example, the average wind speed in Saint-Denis is about 4 m s−1 on 26 January in the afternoon (Fig. S4e) and the wind clearly turns from west (morning) to east (afternoon), simultaneously with the appearance of the layer. The same wind change is detected in Donnas on the same day (Fig. S4f), with easterly wind speeds >1m s−1 for several hours in the afternoon. As a further difference with the first case, the forecasted wind at 1000–2000 m a.s.l. does not show any change in direction typical of the thermal winds. For example, at 2000 m a.s.l. the circulation is continuous and vigorous (up to 6 m s−1), from the afternoon of 26 to the beginning of 29 January. Indeed, this winter case study interestingly shows that thermally driven winds are not the only mechanism, especially in winter, driving the advection of air masses from the Po Valley to the Alps. Rather, the synoptical circulation can push the air masses towards the Alpine valleys, as in this case. In fact, the flow clearly reveals its southern origin at elevations above the mountain crest (e.g. 3000 m a.s.l.), where the wind is not channelled within the main valley. At that altitude, the wind speed is even greater than 20 m s−1. Finally, on 29 January, the measurements in Saint-Denis (gradual increase in the speed of westerly wind) and in Donnas (even stronger wind, again from the west), and COSMO simulations (wind reversal at 1000–2000 m a.s.l.) correlate with the disappearance of the layer better than observations performed at the bottom of the valley (calm wind).
Back trajectories for 26 January are plotted in Fig. S6 and indicate transit over the Po basin starting from the morning (panels a, d), which seems to contradict the fact that the layer arrival over the Aosta Valley is detected by the ALC only since the afternoon. This can be explained by noting that the mean altitude of the trajectories crossing the Po basin during the morning exceeds 1500 m a.s.l. and is thus higher than the Po Valley aerosol layer observed by the ALC in Milan (Fig. 10). The trajectory altitude tends to decrease in the afternoon, reaching the elevations of the polluted boundary layer (Fig. S6b) and thus leading to effective aerosol transport to the Aosta Valley. In fact, considering that each dot in Fig. S6b represents a 1 h step, we estimate a mean air mass residence time in the Po Valley PBL of 30–35 h before arriving over the observing site. Finally, trajectories turn westerly on 29 January, in agreement with the removal of the layer over Aosta (Fig. S6c and f).
Together with the appearance of the aerosol layer, an increase in the COSMO RH can be noticed (Fig. 9b). The latter remains higher, above typical wintertime deliquescence values (e.g. DRH =54 %, D'Angelo et al.2016), for the whole duration of the episode, and never drops below the crystallisation point (e.g. CRH =47 %), which can also be partly attributed to the presence of low clouds forecasted by the NWP model, as actually occurred. The advection is detected more clearly by the increase in SH measured at ground level (from less than 2 g km−1 to a maximum of 4 g kg−1 on 28 January, Fig. S4b). For this episode, the arrival of a different air mass is additionally revealed by the temperature and humidity sensors along the mountain slope. Pseudo-equivalent potential temperatures at different altitudes are shown in Fig. S5. As clearly noticeable, the spread among the series recorded at 550 m a.s.l. and that at higher altitudes remarkably, and quickly, decreases on 26 January, especially during the night, suggesting that the strong (and very shallow) temperature inversion weakens and mixing of the upper aerosol layers down to the surface is favoured.
### 4.2.3 Mass concentrations and particle measurements at the surface
The mass concentration retrieved within the layer by the ALC (Fig. 9c) is quite variable (from 30 µg m−3 at the edge of the layer to more than 100 µg m−3 at the core) and reveals the heterogeneous distribution of the particulate inside the layer. FARM predicts a very different scenario, with three separate increases at the end of 26, 27, and 28 January of non-local origin (coloured background in Fig. 9d, much lower than the concentration retrieved by the ALC) and a clear diurnal cycle close to the surface of local origin (Fig. 9e). The diurnal cycle in the simulations is characterised by two peaks corresponding to the combined effect of traffic rush hours, residential heating, and variation in the mixing layer height. Hourly and sub-hourly PM10 surface concentration measurements at both Aosta–downtown and Aosta–Saint-Christophe, however, only exhibit one peak at midday. Taking into consideration these different daily evolution patterns and the sources included in the emission inventory, the most likely reasons for the differences between the model and the measurements at the surface appear to be an underestimation of the residential heating (actually switched on all day during these very cold days) and an overestimation of the traffic road contribution, together with an overestimation of the mixing layer height growth at midday by the NWP model. Anyway, Fig. 11 shows that the daily averages of PM concentrations measured at several sites of the region are higher on 27–28 January than on the neighbouring days. Specifically, the increase is similar (more than 40 µg m−3) for both PM2.5 and PM10 in Aosta–downtown, which results from the fact that the increment is mainly driven by particles with a diameter of less than 2.5 µm. The maximum PM10 concentration (117 µg m−3) was measured on 28 January in Donnas (Fig. 11h), which is the closest station to the Po basin. The spatial pattern of the observed increase, not fully captured by the model, is evident in Fig. S7 and represents a further indication of the Po Valley being the source of the polluted air masses. Moreover, Fig. 11c, d show this increase to be associated with enhancement in Aosta–downtown of the nitrate and ammonium components (see next paragraph), two key species of the Po Valley secondary aerosol, but minor contributors to PM10 in the Aosta Valley. Finally, while the daily PM concentrations from FARM are comparable, on average, to the measurements, the modulation of the PM concentration by the advection (peaks) is not captured by the model, whose output is rather constant. Most interestingly, data collected at remote and usually pristine sites also show a remarkable increase: at La Thuile (PM10 winter average 7 µg m−3), the hourly PM10 concentration (Fig. 9e) reaches nearly 40 µg m−3 (some hours later than the appearance of the aerosol layer in Aosta–Saint-Christophe) and correlates well with the increasing NO2 concentration (from about 2 µg m−3 before and after the event to 44 µg m−3 during the event on an hourly basis) measured by a co-located detector. Additionally, the mobile laboratory in Antey (winter average 20 µg m−3) measures increasing daily PM10 concentrations with a maximum of 69 µg m−3 on 27 January (Fig. 11g) and increasing NO2 concentrations from about 30 to 56 µg m−3.
Figure 11Measured (coloured bars) and simulated (dotted line) PM2.5 and PM10 daily concentrations at several sites of the Aosta Valley (a, b, g, h); percentage concentrations of nitrate (c), ammonium (d), and sulfate (e) and OC∕EC ratio (f) at Aosta–downtown during case study 2 (January 2017). The period when the ALC detects a thick layer above Aosta–Saint-Christophe is highlighted with a grey background.
For this selected sequence of days, the data collected by the OPC in Aosta–Saint-Christophe are additionally available. The instrument reveals a notable increase in the number concentration for particles smaller than 0.5 µm (Fig. S4c) in coincidence with the arrival of the aerosol layer. The total number concentration (Fig. S4d) gradually increases from a few hundred up to 3000 particles cm−3 and decreases again on 29 January (the average value in winter 2016–2017 in conditions of local pollution being 650 particles cm−3).
## 4.3 Case study 3: spring (May 2017)
This third case, occurring in spring, is similar to the first one (Sect. 4.1) but is included to represent a third season and because a more extended observational dataset was available. From a meteorological point of view, a wide high-pressure ridge extended from the Mediterranean Sea to western and central Europe, thus favouring sunny days with afternoon instabilities and thermally driven winds from the Po basin to the Aosta Valley. At the end of the period, a weakening of the high-pressure area led to increased instability. The whole advection episode (25 May–3 June 2017) lasted for 10 consecutive days. In the next paragraphs, we will mainly focus on the interval of 24–30 May.
### 4.3.1 ALC observations
Since the establishment of the thermally driven wind regime, starting from 25 May, a thick aerosol layer is regularly detected by the ALC in the afternoon (Fig. 12a). The layer persists during each night, when the scattering ratio increases up to a value of 20 and clouds systematically form within the layer. This aerosol layer extends from the ground to an altitude increasing from 2.5 km at the beginning of the case study to more than 3 km at the end of the episode.
Figure 12Case study of 24–30 May 2017. (a) Coloured background: vertical profile of scattering ratio from ALC in Aosta–Saint-Christophe. Arrows: horizontal velocity of the wind measured at the surface and simulated by COSMO at several elevations. (b) Vertical profile of relative humidity forecasted by COSMO. (c) Vertical profile of PM10 mass concentration derived from the ALC using the functional relationships. (d) Mass concentration (PM10w) from FARM. (e) Hourly and sub-hourly PM10 (dry) surface concentration from FARM simulations and observations in Aosta–Saint-Christophe and Aosta–downtown.
### 4.3.2 Meteorological variables and back trajectories
The plain-to-mountain circulation, driving the phenomenon under investigation, is well captured by both measurements at the surface (Fig. 12a, bold arrows) and COSMO forecasts (thin arrows). Eastern winds with speeds >10m s−1 are measured in the afternoon till sunset at the surface, while nights are characterised by calm wind. At higher elevations, the wind provenance turns from the north, at the start of the depicted sequence, to the south.
The back trajectories ending over the Aosta Valley during the third episode are plotted in Fig. S8. On 25 May, the large-scale circulation from the north generally dominates the air mass origin (Fig. S8a and d). However, during the day, the low-level thermal circulation becomes strong enough to influence the lowest trajectories, which start to cross the Po Valley in the second part of the day (Fig. S8b), in line with the simultaneous appearance of an aerosol layer in the ALC measurements. Together with their rotation during this day, the trajectories also decrease their altitude. At the end of the day, the air masses reaching the station travelled for more than 20 h on the surface of the Po basin. The end of the episode is marked again by northwestern provenance (Fig. S8c and f).
As in the first case, COSMO accurately predicts the advection of humid air at the same times as the ALC detects a thickening of the layer (Fig. 12b). At night, the simulated and measured RHs exceed 90 % at altitude and 80 % at ground level (Figs. 12 and S9b). Contrary to RH, SH does not show any daily cycle (Fig. S9b). A sudden SH increase (5 to 10 g kg−1) is clearly visible on 25 May at the time of the advection, while the values for the following days are almost constant except on the occasion of short showers (e.g. evening of 28 May).
### 4.3.3 Mass concentrations and particle measurements at the surface
The aerosol mass derived from the ALC is presented in Fig. 12c. The maximum concentration retrieved by this method within the aerosol layer is higher than 60 µg m−3 just before the formation of clouds at night. Again, FARM (Fig. 12d) qualitatively reproduces the afternoon increase in aerosol concentrations owing to transport from the boundaries; however the simulated concentrations are much lower (about 4–5 times) than the retrievals from the ALC and the advection arrival times are anticipated compared to the appearance of the thick layer from the ceilometer.
Hourly and sub-hourly PM10 surface concentrations (measured in Aosta–downtown and Aosta–Saint-Christophe and simulated by FARM) are presented in Fig. 12e. FARM correctly reproduces the morning rush-hour peak, but the concentrations are about half those from the PM samplers. The series in Fig. 12e shows an increase in PM10 surface concentration during 25 May, with persisting high values for the rest of the week, most noticeably during the night. Accordingly, PM daily means in Fig. 13a, b, g, h show a distinct increase in the whole region (the concentrations doubles) during the case study compared to the preceding and following days (and also compared to the 2015–2017 average concentrations for the same period, i.e. 12 µg m−3 for PM10 in Aosta–downtown and Donnas and 6 µg m−3 for PM2.5 in Aosta–downtown).
Figure 13Measured (coloured bars) and simulated (dotted line) PM2.5 and PM10 concentrations at several sites of the Aosta Valley (a, b, g, h); percentage concentrations of nitrate (c), ammonium (d), and sulfate (e) and OC∕EC ratio (f) at Aosta–downtown during case study 3 (May–June 2017). The period when the ALC detects a thick layer above Aosta–Saint-Christophe is highlighted with a grey background.
The number distribution and total particle number measured by the OPC in Aosta–Saint-Christophe are plotted in Fig. S9c and d, respectively. Figure S9 shows a notable increase in the number concentration during 25 May (from less than 200 to more than 800 particles cm−3) and in the afternoon of each day, and a decrease in the central part of each day as soon as the valley convection starts and the mixing layer height increases.
### 4.3.4 Chemical analyses
Percentage concentrations of nitrate, ammonium and sulfate are represented in Fig. 13c–e and account for about 20 %–25 % of the total PM10 mass (as a reference, this fraction represents less than 15 % for non-advection days in May–June 2017). Interestingly, relative nitrate concentration does not change much and does not reach the extreme values of the winter case study. Indeed, transfer of ammonium nitrate from particles to the gas phase, which is not measured, is favoured by higher temperatures . Conversely, ammonium and sulfate increase remarkably during advection, reaching typical concentrations of the Po Valley in that period . In particular, the sulfate concentration is much higher and more affected by the advection in May than during the winter case. The role reversal between nitrate and sulfate in case studies 2 and 3 results from the different sensitivity of those compounds to temperature and atmospheric conditions . Again, the contribution of inorganic species from the model does not agree with the analyses: the contribution by ammonium and sulfate is strongly underestimated, while the peaks in the simulated nitrate concentration are not reflected in the analyses.
As for the organic part, OM and EC are the main constituents of the remaining fraction, with about 60 % and 6 %, respectively. Although the available dataset is rather short, the OC∕EC ratio during the event almost doubles (values of 6.1–7.2) compared to the value before (3.7) and after (3.3) the event. This increase in the OC fraction during transport episodes is confirmed by the long-term analysis .
### 4.3.5 Sun photometer measurements
The same morning–midday–afternoon modulation can be observed in the AOD from both the ALC and the sun photometer (Fig. S9e). The high AOD values in the first and last part of the day (up to 0.30–0.40 at 500 nm) and the decrease in the middle of the day (down to 0.12 at 500 nm) match the appearance of the layer seen by the ALC and its enhancement due to hygroscopic effects, in accordance with the results of for a typical site in the Po basin (in that case, for RH =90 %, the extinction coefficient increased on average to 180 % of the value measured for RH =0 %). The steep rise (from 0.8 to 1.7) in the Ångström exponent on 25 May (Fig. S9f) and its continuous increase in the following days (up to nearly 2.0) may be attributed to the advection of small particles to the measuring site. The SSA fluctuates around large values (generally between 0.9 and 1.0), typical of weakly light-absorbing or aged aerosol. Most interestingly, the volume distribution (Fig. S9g) exhibits an abrupt decrease in the peak diameter during the morning hours (e.g. from 0.5 µm at 06:40 UTC to 0.2 µm at midday on 27 May), strengthening the hypothesis of aerosol hydration at night and dehydration during the day as temperature increases and RH decreases.
## 4.4 Model–measurement discrepancies
Our CTM qualitatively reproduces the aerosol advection in all three case studies. It helps to understand the phenomenon by allowing us to switch the non-local sources on or off (boundary conditions) but fails to quantitatively explain the concentrations retrieved by the ALC (PM10w) and measured by the air quality network (PM10). As already mentioned in the description of the three cases, the model (a) underestimates the PM mass both in the layer aloft and at the surface and (b) anticipates the peak concentrations compared to the profiles from the ALC. A variety of (possibly concurrent) reasons can explain the observed underestimation, mainly related to the following.
1. Inaccuracies in retrieving the PM concentration from the ALC backscatter can lead to overestimation in the ALC-determined PM. As mentioned, ALC measures aerosol backscatter, so that specific tools were developed and are used here to associate a PM value with it. Still, the expected error associated with these estimates is of the order of 30 %–40 %. In addition, the ALC retrieval is based on functional relationships derived assuming a maximum RH of 95 %. Higher FARM–ALC discrepancies can be expected when RH > DRH, and particularly at RH >95 %;
2. Inaccuracies in the CTM simulations can lead to underestimation in the simulated PM. The emission inventory used within FARM likely underestimates the real emissions, as also reported in other cases, and for different models, in the scientific literature (e.g. EMEP2016; Uchino et al.2017). In particular, the boundary conditions could not be accurate enough for our aims owing to the abrupt change of the national emission inventory grid resolution (12 km) to the local scale (1 km). This issue can affect the comparison between the model (dry PM10) and surface measurements, especially in winter, as discussed more extensively in the companion paper . Additionally, the aerosol hygroscopicity may not be optimally simulated by FARM, e.g. due to a wrong characterisation of the chemical properties of the modelled aerosol, which again impacts the comparison between the vertical profiles from the model and the ALC. Finally, some underestimation of PM values could also be due to overestimation of the FARM-simulated PBL height. An evaluation of this kind of effect is in principle possible by comparing the simulations with the ALC-derived PBL height . However, this should be performed only selecting non-advection conditions, i.e. those in which the ceilometer signal is only affected by local aerosols and is thus able to follow the daily evolution of the local PBL using local particles as tracers. This kind of investigation was, however, beyond the scope of the present work. Challenges and recent efforts to define a PBL in mountainous areas (“mountain boundary layer”, MBL) and discrepancies between the MBL and the aerosol layer are more extensively described by .
The case studies described here show that several of the previous points most likely play a significant role. Some sensitivity tests were performed addressing point 2. In particular, for the first case study (August 2015, Sect. 4.1) we performed two additional tests. (1) We doubled the PM concentrations from the boundary conditions to assess the sensitivity of the simulated vertical profiles to the accuracy of the national emission inventory and to the transport from outside the administrative boundaries of the Aosta Valley, while leaving the regional emission inventory unchanged. The perturbation of the boundary conditions used for the test may appear excessively large; however this choice could be supported by the fact that the resolution of the national inventory grid is much coarser than the local one, which may be a source of inaccuracies. (2) We employed two different, more empirical parametrisations of the aerosol hygroscopicity to recalculate water uptake by aerosol. As shown in the Supplement (Sect. S7), the results of the two tests support the hypothesis that both the national inventory and the parametrisation of the hygroscopic effects in the model are responsible for the discrepancies between simulations and measurements in the first case study. Doubling the boundary conditions also slightly improves the comparison between simulations and measurements at the surface for the winter case study (first introduced in Sect. 4.2), although some discrepancies in the geographic distribution of the concentrations persist (Fig. S12, e.g. overestimation on 25 January 2017 and underestimation on the following days), probably due to inaccurate NWP input data. Finally, it is worth mentioning that, during the winter episode, a small fraction of the detected secondary particulate might form locally due to heterogeneous chemical reactions taking place on the advected particles themselves . These dynamics could contribute to the observed underestimation; however they are too complex to be simulated by present CTMs. Further efforts on this topic are scheduled for the future.
The previous considerations, however, fail at comprehensively explaining the time shifts sometimes noticeable between the model and the measurements, i.e. anticipation of the advection arrival time (even in “dry” conditions in the afternoon on the first day of each sequence) and of the layer disappearance in the morning (in which hygroscopicity may have an important role). Although an accurate assessment would require a more sophisticated set of instruments to characterise the vertical profile of the wind velocity, here we formulate some hypotheses.
1. The NWP model likely anticipates and overestimates the easterly thermally driven winds in the first hours of the afternoon. This is noticeable, for example, in Fig. S13, in which the zonal component of the wind from both COSMO and the surface measurements for case study 1 (August 2015) is plotted, and, on a longer statistical basis, in Fig. S1b, c, showing that the model has the tendency to see easterly winds more often and with higher intensity compared to the observations. A possible reason for that is the smoothed valley orography used in the NWP model compared to the real one. This is displayed in Fig. S14, showing the difference of the digital elevation model (DEM) used within COSMO and a more realistic DEM (10 m resolution): both valleys and mountain crests are clearly smoothed out by COSMO, with absolute differences well >500m (and up to 1000 m). This difference could additionally explain why the altitude of the entrainment zone (i.e. the boundary between the free atmosphere and the boundary layer where the thermally driven circulation develops) is underestimated by COSMO compared to the height of the aerosol layer detected by the ALC (e.g. Figs. 3 and 12).
2. COSMO overestimates the nighttime drainage winds (katabatic winds), as noticeable, again, from Fig. S13 for case study 1. This might trigger enhanced cleansing of the lower atmospheric layers during the night as simulated by FARM (see, e.g. the Supplement video file relative to Fig. 6, https://doi.org/10.5446/38391), but undetected by the ALC. An overestimation of the drainage winds would also explain the differences between the simulated and measured daily cycle of SH, represented in Fig. S15 for case study 1 as an example. In fact, the measured SH usually increases during the first advection day as a result of the transport from source areas with more stagnating conditions (cf. Figs. 3, 9, and 12) but stays rather constant for the rest of the episode. Conversely, COSMO yields larger dynamics, with SH maxima in the late afternoon and a subsequent decrease, likely owing to overestimated drainage winds developing after sunset (this results in a SH minimum in the late morning).
As a final remark, we also mention that the 2.8 km grid resolution of the COSMO-I2 model might still be insufficient for resolving the complex 3-D flow field of an Alpine valley and is too coarse to reproduce the mountain atmosphere with its various mixing processes. Follow-up studies using next-generation NWP models with increased resolution (1 km or lower) would be of great interest. Conversely it should also be noticed that decreasing the grid spacing below the scale for which turbulence parametrisations have been developed, i.e. modelling the “grey zone” (or “terra incognita”; e.g. Wyngaard2004), does not necessarily lead to better performances. In this context, comparison of high-resolution simulations with our vertically resolved dataset could represent a challenging future benchmark for this relevant topic of ongoing research.
5 Conclusions
We investigated the phenomenology of recurrent episodes of wind-driven arrival of aerosol layers in the northwestern Italian Alps, and specifically in the Aosta Valley. The analysis was performed by combining a multiple-site, multiple-sensor measurement dataset with modelling tools. Through a deep examination of three case studies, specifically selected within a 3-year dataset as clear examples of the phenomenon under investigation, we can provide the following answers to the scientific questions driving the study (see Introduction).
1. What is the origin of the aerosol layers detected in the northwestern Alps?
All results agreed in showing these episodes to be associated with the arrival of polluted air masses originating from the Po basin, one of the European pollution hotspots. To reach this conclusion, we examined wind flows from both the experimental (surface observations of the wind velocity from the meteorological network at multiple elevations) and modelling (high-resolution NWP models, back trajectories, and CTM simulations) perspectives. Interestingly, in one case (Sect. 4.2.2), calm wind measurements at the bottom of the valley in cold-pool conditions at the beginning of the advection episode could give the mistaken impression that the aerosol originated from local sources since the circulation in the lowermost levels was inactive, while the wind was blowing undisturbed above the temperature inversion. However, the ALC capacities of sounding the vertical profile of the atmosphere, together with the experimental and modelling data at different elevations, turned out to be a substantial benefit for the clear understanding of the phenomenon.
2. What conditions are favourable to the aerosol flow into the valley?
We show that these advections are due to thermally driven winds (especially in the warm period of the year, e.g. case studies 1 and 3) or synoptic flows (mainly in the cold season, e.g. case 2) from the east (Po basin) to the west. A more systematic analysis of the flow regimes and their impacts on transport based on comprehensive statistics are provided in the companion paper exploiting the full 3-year record of ALC measurements. These show that conditions favourable for the development of the advections occur on >50 % of the days on average. Also, we expect the frequency of the advections to increase with increasing proximity to the source (Po basin).
3. How do the advected aerosol layers evolve in both altitude and time?
Thanks to the monitoring capacity (24∕7) of the ALCs, we could follow the evolution of the aerosol layer in both altitude and time. We show that the advected aerosol layers can extend up to 4000 m a.s.l. in the warm season, which incidentally points out the potential impacts of aerosol dry and wet depositions on the remote high-altitude ecosystems. Conversely, the altitude of the layer sounded by the ALC is a clear indication that the emissions are not local. As for the evolution in time, the layers were usually detected to arrive over Aosta in the afternoon, when the plain–mountain thermal regime is established. However, the backscatter from the ALC was found to reach its maximum during the night, when water uptake on aerosol took place and clouds could frequently form within the aerosol layer.
4. What is the impact of the transported aerosol on PM surface concentrations and chemical composition?
An important increase in PM10 and PM2.5 was detectable during the investigated advections, with up to 80 µg m−3 of PM10 likely transported in Donnas (Fig. 11). The size distribution of the advected particles generally peaks in the accumulation mode, with a diameter of a few tenths of a micrometre (as observed by both the OPC, at the surface, and the sun photometer, in the uppermost layers). Moreover, this kind of particulate is weakly light-absorbing (sun photometer). Chemical analyses reveal these layers to produce an increase in the secondary inorganic fraction, composed by nitrate, sulfate, and ammonium, i.e. three typical compounds found in the Po Valley atmosphere, and with low deliquescence RH. Weak local formation of secondary particulate could not be excluded during episodes of severe advection (e.g. case study 2), probably also due to aqueous phase chemistry. However, including these latter processes in current CTMs is still challenging. In one of the case studies, the OC∕EC ratio was also observed to increase, a possible sign of the transport of organic compounds from the Po basin.
5. Are the presently used CTMs able to reproduce and explain the observations along the vertical profile?
Our investigation allowed an evaluation of the FARM model. Notably, FARM could reproduce the observed arrival of elevated aerosol layers and it correctly attributed them to sources external to the Aosta Valley. However, absolute values of PM concentrations and the timing of the advections were poorly reproduced, with underestimations of aerosol concentrations and time anticipations compared to the measurements. On the basis of a sensitivity study, the former issue may be partly attributed to both water uptake by highly hygroscopic particles, not fully taken into account in the model, and deficiencies in the emission inventories, especially owing to the coarse resolution of the national one (12 km). As for the timing discrepancies, suboptimal performances of the NWP model to simulate daytime (thermally driven) and nighttime (katabatic) winds are the most likely sources of error. Despite these limitations, FARM brought insights into the phenomenology addressed, supporting the observations and helping to interpret them. Conversely, the observation-based results of this work could drive the improvement of the emission inventories, thus enhancing the reliability of the CTM (e.g. Diémoz et al.2019). In turn, this could allow the extension of the findings of this work to a wider domain, not covered (or not fully covered) by observations.
The phenomenology described in detail in the current study through the selected cases has been further investigated in the companion paper, exploiting the complete observational dataset over the period 2015–2017, complemented by a long-term simulation by the FARM model. This wider dataset, inspected by statistical techniques and classification schemes, allowed a quantitative evaluation of the long-term impact of the aerosol transported from the Po basin to the air quality in the northwestern Alps. Still, future work is needed to investigate possible local and basin-wide strategies to effectively mitigate this impact.
Data availability
Data availability.
The ALC data are available upon request to the ALICEnet ([email protected]) and E-PROFILE (http://data.ceda.ac.uk/badc/eprofile/data/; ) networks. The sun photometer data can be downloaded from the EuroSkyRad network web site (http://www.euroskyrad.net/index.html; ) after authentication (credentials may be requested from Monica Campanelli, [email protected]). The measurements from the ARPA air quality surface network are available at the web page http://www.arpa.vda.it/it/aria/la-qualità-dell-aria/stazioni-di-monitoraggio/inquinanti-export-dati . The wind data in Milan refer to the ClimateNetwork® weather station Milan Bicocca and were kindly provided by Fondazione OMD. The weather data from the Aosta–Saint-Christophe and Saint-Denis stations can be retrieved from http://cf.regione.vda.it/richiesta_dati.php (last access: 28 February 2019) upon request to Centro Funzionale della Valle d'Aosta. The MAIAC data were made available by Alexei Lyapustin (NASA). The rest of the data can be requested from the corresponding author ([email protected]).
Video supplement
Video supplement.
Video file (https://doi.org/10.5446/38391; ) showing the simulated 4-D evolution of PM concentrations over the Aosta Valley (a snapshot being provided in Fig. 6).
Supplement
Supplement.
Author contributions
Author contributions.
HD, FB, and GPG conceived and designed the study and contributed to the interpretation of the results. TM supplied the meteorological observations and numerical weather predictions. GP performed the chemical transport simulations. DD provided the ALC functional relationships and assistance on the Rayleigh ALC calibration with inputs from MH. SP carried out the EC∕OC analyses and IKFT helped with the interpretation of the chemical speciation. MC supplied the POM calibration factors. FB and LDC prepared the satellite radiometer data. LDL and LF provided the ALC data from Milan. HD analysed the data and wrote the paper with contributions from FB, GPG, and all co-authors.
Competing interests
Competing interests.
The authors declare that they have no conflict of interest.
Special issue statement
Special issue statement.
Acknowledgements
Acknowledgements.
The authors would like to thank Alessandra Brunier, Giuliana Lupato, Paolo Proment, Stefania Vaccari, and Maria Cristina Gibellino (ARPA Valle d'Aosta) for carrying out the chemical analyses; Marco Pignet, Claudia Tarricone, and Manuela Zublena (ARPA Valle d'Aosta) for providing the data from the air quality surface network; Fondazione OMD and Centro Funzionale della Valle d'Aosta for the additional meteorological series; Alexei Lyapustin (NASA) for the MAIAC data; and Silvia Ferrarese (Turin University) for the exchange about high-resolution models in the “terra incognita” regime. The authors would like to acknowledge the valuable contribution of the discussions in the working group meetings organised by COST Action ES1303 (TOPROF). They also gratefully acknowledge the Institute for Atmospheric and Climate Science, ETH Zurich, Switzerland, for the provision of the LAGRANTO software used in this publication. The contribution of Luca Ferrero is an outcome of the GEMMA Center, in the framework of Project MIUR – Dipartimenti di Eccellenza 2018–2022.
Reviewed by: four anonymous referees
References
Adam, M., Putaud, J. P., Martins dos Santos, S., Dell'Acqua, A., and Gruening, C.: Aerosol hygroscopicity at a regional background site (Ispra) in Northern Italy, Atmos. Chem. Phys., 12, 5703–5717, https://doi.org/10.5194/acp-12-5703-2012, 2012. a, b
Agnesod, G., Moulin, P.-A., Pession, G., Villard, H., and Zublena, M.: Étude Air Espace Mont-Blanc – Rapport Technique, Tech. rep., Espace Mont Blanc, available at: http://www.arpa.vda.it/images/stories/ARPA/aria/progetti/progairmb_agnesod_2003.pdf (last access: 28 February 2019), 2003. a
Aksoyoglu, S., Ciarelli, G., El-Haddad, I., Baltensperger, U., and Prévôt, A. S. H.: Secondary inorganic aerosols in Europe: sources and the significant influence of biogenic VOC emissions, especially on ammonium nitrate, Atmos. Chem. Phys., 17, 7757–7773, https://doi.org/10.5194/acp-17-7757-2017, 2017. a
Anfossi, D., Cassardo, C., Giraud, C., Longhetto, A., Villone, B., Bacci, P., Bonelli, P., Carboni, G., Bonafè, U., Bonasoni, P., and Giovanelli, G.: Experimental study of transalpine transport of trace effluents: a comparison with synoptic trajectories of airflow, Nuovo Cimento C, 11, 489–526, https://doi.org/10.1007/BF02506997, 1988. a
Angelini, F., Barnaba, F., Landi, T. C., Caporaso, L., and Gobbi, G. P.: Study of atmospheric aerosols and mixing layer by LIDAR, Radiat. Prot. Dosim., 137, 275–279, https://doi.org/10.1093/rpd/ncp219, 2009. a
Ångström, A.: On the Atmospheric Transmission of Sun Radiation and on Dust in the Air, Geogr. Ann., 11, 156–166, 1929. a
ARPA Valle d'Aosta: Air quality data, available at: http://www.arpa.vda.it/it/aria/la-qualità-dell-aria/stazioni-di-monitoraggio/inquinanti-export-dati, last access: 7 March 2019. a
Bacco, D., Trentini, A., Minguzzi, E., Amorati, R., Zigola, C., Deserti, M., and Poluzzi, V.: Chimica del particolato e meteo, un'analisi sul campo, Ecoscienza, 1, available at: https://www.arpae.it/cms3/documenti/_cerca_doc/ecoscienza/ecoscienza2017_1/bacco _et_al_es2017_01.pdf (last access: 28 February 2019), 2017. a, b
Baldauf, M., Seifert, A., Förstner, J., Majewski, D., Raschendorfer, M., and Reinhardt, T.: Operational Convective-Scale Numerical Weather Prediction with the COSMO Model: Description and Sensitivities, Mon. Weather Rev., 139, 3887–3905, https://doi.org/10.1175/MWR-D-10-05013.1, 2011. a
Barnaba, F. and Gobbi, G. P.: Lidar estimation of tropospheric aerosol extinction, surface area and volume: Maritime and desert-dust cases, J. Geophys. Res., 106, 3005–3018, https://doi.org/10.1029/2000JD900492, 2001. a
Barnaba, F. and Gobbi, G. P.: Modeling the Aerosol Extinction versus Backscatter Relationship for Lidar Applications: Maritime and Continental Conditions, J. Atmos. Ocean. Tech., 21, 428–442, https://doi.org/10.1175/1520-0426(2004)021<0428:MTAEVB>2.0.CO;2, 2004. a
Barnaba, F., Gobbi, G. P., and de Leeuw, G.: Aerosol stratification, optical properties and radiative forcing in Venice (Italy) during ADRIEX, Q. J. Roy. Meteor. Soc., 133, 47–60, https://doi.org/10.1002/qj.91, 2007. a, b, c
Barnaba, F., Putaud, J. P., Gruening, C., dell'Acqua, A., and Dos Santos, S.: Annual cycle in co-located in situ, total-column, and height-resolved aerosol observations in the Po Valley (Italy): Implications for ground-level particulate matter mass concentration estimation from remote sensing, J. Geophys. Res., 115, D19209, https://doi.org/10.1029/2009JD013002, 2010. a
Belis, C., Blond, N., Bouland, C., Carnevale, C., Clappier, A., Douros, J., Fragkou, E., Guariso, G., Miranda, A. I., Nahorski, Z., Pisoni, E., Ponche, J.-L., Thunis, P., Viaene, P., and Volta, M.: Strengths and Weaknesses of the Current EU Situation, Springer International Publishing, 69–83, https://doi.org/10.1007/978-3-319-33349-6_4, 2017. a
Bigi, A. and Ghermandi, G.: Trends and variability of atmospheric PM2.5 and PM10−2.5 concentration in the Po Valley, Italy, Atmos. Chem. Phys., 16, 15777–15788, https://doi.org/10.5194/acp-16-15777-2016, 2016. a
Binkowski, F.: Science Algorithms of the EPA Models-3 Community Multiscale Air Quality (CMAQ) Modeling System, vol. EPA/600/R-99/030, chap. The aerosol portion of Models-3 CMAQ, edited by: Byun, D. W. and Ching, J. K. S., 1999. a
Birch, M. E. and Cary, R. A.: Elemental Carbon-Based Method for Monitoring Occupational Exposures to Particulate Diesel Exhaust, Aerosol Sci. Tech., 25, 221–241, https://doi.org/10.1080/02786829608965393, 1996. a
Borghi, S. and Giuliacci, M.: Circulation features driven by diurnal heating in the lower atmospheric layers of the Po Valley, Nuovo Cimento C, 3, 1–16, https://doi.org/10.1007/BF02509187, 1980. a
Bourgeois, I., Savarino, J., Caillon, N., Angot, H., Barbero, A., Delbart, F., Voisin, D., and Clément, J.-C.: Tracing the Fate of Atmospheric Nitrate in a Subalpine Watershed Using Δ17O, Environ. Sci. Technol., 52, 5561–5570, https://doi.org/10.1021/acs.est.7b02395, 2018. a
Bucci, S., Cristofanelli, P., Decesari, S., Marinoni, A., Sandrini, S., Größ, J., Wiedensohler, A., Di Marco, C. F., Nemitz, E., Cairo, F., Di Liberto, L., and Fierli, F.: Vertical distribution of aerosol optical properties in the Po Valley during the 2012 summer campaigns, Atmos. Chem. Phys., 18, 5371–5389, https://doi.org/10.5194/acp-18-5371-2018, 2018. a, b
Burkhardt, J., Zinsmeister, D., Grantz, D. A., Vidic, S., Sutton, M. A., Hunsche, M., and Pariyar, S.: Camouflaged as degraded wax: hygroscopic aerosols contribute to leaf desiccation, tree mortality, and forest decline, Environ. Res. Lett., 13, 085001, https://doi.org/10.1088/1748-9326/aad346, 2018. a
Calori, G., Silibello, C., and Marras, G.: FARM (Flexible Air quality Regional Model) Model formulation and user's Manual, Arianet, 4.7 Edn., 2014. a
Campanelli, M., Estellés, V., Tomasi, C., Nakajima, T., Malvestuto, V., and Martínez-Lozano, J. A.: Application of the SKYRAD Improved Langley plot method for the in situ calibration of CIMEL Sun-sky photometers, Appl. Optics, 46, 2688–2702, https://doi.org/10.1364/AO.46.002688, 2007. a, b
Campanelli, M., Mascitelli, A., Sanò, P., Diémoz, H., Estellés, V., Federico, S., Iannarelli, A. M., Fratarcangeli, F., Mazzoni, A., Realini, E., Crespi, M., Bock, O., Martínez-Lozano, J. A., and Dietrich, S.: Precipitable water vapour content from ESR/SKYNET sun–sky radiometers: validation against GNSS/GPS and AERONET over three different sites in Europe, Atmos. Meas. Tech., 11, 81–94, https://doi.org/10.5194/amt-11-81-2018, 2018. a, b
Carbone, C., Decesari, S., Mircea, M., Giulianelli, L., Finessi, E., Rinaldi, M., Fuzzi, S., Marinoni, A., Duchi, R., Perrino, C., Sargolini, T., Vardè, M., Sprovieri, F., Gobbi, G., Angelini, F., and Facchini, M.: Size-resolved aerosol chemical composition over the Italian Peninsula during typical summer and winter conditions, Atmos. Environ., 44, 5269–5278, https://doi.org/10.1016/j.atmosenv.2010.08.008, 2010. a
Carbone, C., Decesari, S., Paglione, M., Giulianelli, L., Rinaldi, M., Marinoni, A., Cristofanelli, P., Didiodato, A., Bonasoni, P., Fuzzi, S., and Facchini, M. C.: 3-year chemical composition of free tropospheric PM1 at the Mt. Cimone GAW global station – South Europe – 2165 m a.s.l., Atmos. Environ., 87, 218–227, https://doi.org/10.1016/j.atmosenv.2014.01.048, 2014. a, b
Carslaw, K. S., Boucher, O., Spracklen, D. V., Mann, G. W., Rae, J. G. L., Woodward, S., and Kulmala, M.: A review of natural aerosol interactions and feedbacks within the Earth system, Atmos. Chem. Phys., 10, 1701–1737, https://doi.org/10.5194/acp-10-1701-2010, 2010. a
Carter, W.: Documentation of the SAPRC-99 Chemical Mechanism for VOC Reactivity Assessment. Final Report to California Air Resources Board, Contract 92-329 and 95-308, SAPRC, Tech. rep., University of California, Riverside, CA, available at: http://www.engr.ucr.edu/~carter/pubs/s99doc.pdf (last access: 28 February 2019), 2000. a
Caserini, S., Giani, P., Cacciamani, C., Ozgen, S., and Lonati, G.: Influence of climate change on the frequency of daytime temperature inversions and stagnation events in the Po Valley: historical trend and future projections, Atmos. Res., 184, 15–23, https://doi.org/10.1016/j.atmosres.2016.09.018, 2017. a
Cavalli, F., Viana, M., Yttri, K. E., Genberg, J., and Putaud, J.-P.: Toward a standardised thermal-optical protocol for measuring atmospheric organic and elemental carbon: the EUSAAR protocol, Atmos. Meas. Tech., 3, 79–89, https://doi.org/10.5194/amt-3-79-2010, 2010. a
Cesaroni, G., Badaloni, C., Gariazzo, C., Stafoggia, M., Sozzi, R., Davoli, M., and Forastiere, F.: Long-term exposure to urban air pollution and mortality in a cohort of more than a million adults in Rome, Environ. Health Persp., 121, 324–331, https://doi.org/10.1289/ehp.1205862, 2013. a
Charron, A., Harrison, R. M., Moorcroft, S., and Booker, J.: Quantitative interpretation of divergence between PM10 and PM2.5 mass measurement by TEOM and gravimetric (Partisol) instruments, Atmos. Environ., 38, 415–423, https://doi.org/10.1016/j.atmosenv.2003.09.072, 2004. a
Chu, D. A., Kaufman, Y. J., Zibordi, G., Chern, J. D., Mao, J., Li, C., and Holben, B. N.: Global monitoring of air pollution over land from the Earth Observing System-Terra Moderate Resolution Imaging Spectroradiometer (MODIS), J. Geophys. Res., 108, 4661, https://doi.org/10.1029/2002JD003179, 2003. a
Chudnovsky, A. A., Koutrakis, P., Kloog, I., Melly, S., Nordio, F., Lyapustin, A., Wang, Y., and Schwartz, J.: Fine particulate matter predictions using high resolution Aerosol Optical Depth (AOD) retrievals, Atmos. Environ., 89, 189–198, https://doi.org/10.1016/j.atmosenv.2014.02.019, 2014. a
Clerici, M. and Mélin, F.: Aerosol direct radiative effect in the Po Valley region derived from AERONET measurements, Atmos. Chem. Phys., 8, 4925–4946, https://doi.org/10.5194/acp-8-4925-2008, 2008. a
Collaud Coen, M., Andrews, E., Aliaga, D., Andrade, M., Angelov, H., Bukowiecki, N., Ealo, M., Fialho, P., Flentje, H., Hallar, A. G., Hooda, R., Kalapov, I., Krejci, R., Lin, N.-H., Marinoni, A., Ming, J., Nguyen, N. A., Pandolfi, M., Pont, V., Ries, L., Rodríguez, S., Schauer, G., Sellegri, K., Sharma, S., Sun, J., Tunved, P., Velasquez, P., and Ruffieux, D.: Identification of topographic features influencing aerosol observations at high altitude stations, Atmos. Chem. Phys., 18, 12289–12313, https://doi.org/10.5194/acp-18-12289-2018, 2018. a
Cong, Z., Kawamura, K., Kang, S., and Fu, P.: Penetration of biomass-burning emissions from South Asia through the Himalayas: new insights from atmospheric organic acids, Sci. Rep.-UK, 5, 9580, https://doi.org/10.1038/srep09580, 2015. a
Cristofanelli, P., Marinoni, A., Arduini, J., Bonafè, U., Calzolari, F., Colombo, T., Decesari, S., Duchi, R., Facchini, M. C., Fierli, F., Finessi, E., Maione, M., Chiari, M., Calzolai, G., Messina, P., Orlandi, E., Roccato, F., and Bonasoni, P.: Significant variations of trace gas composition and aerosol properties at Mt. Cimone during air mass transport from North Africa – contributions from wildfire emissions and mineral dust, Atmos. Chem. Phys., 9, 4603–4619, https://doi.org/10.5194/acp-9-4603-2009, 2009. a
Cugerone, K., De Michele, C., Ghezzi, A., Gianelle, V., and Gilardoni, S.: On the functional form of particle number size distributions: influence of particle source and meteorological variables, Atmos. Chem. Phys., 18, 4831–4842, https://doi.org/10.5194/acp-18-4831-2018, 2018. a
Curci, G., Ferrero, L., Tuccella, P., Barnaba, F., Angelini, F., Bolzacchini, E., Carbone, C., Denier van der Gon, H. A. C., Facchini, M. C., Gobbi, G. P., Kuenen, J. P. P., Landi, T. C., Perrino, C., Perrone, M. G., Sangiorgi, G., and Stocchi, P.: How much is particulate matter near the ground influenced by upper-level processes within and above the PBL? A summertime case study in Milan (Italy) evidences the distinctive role of nitrate, Atmos. Chem. Phys., 15, 2629–2649, https://doi.org/10.5194/acp-15-2629-2015, 2015. a, b
D'Angelo, L., Rovelli, G., Casati, M., Sangiorgi, G., Perrone, M. G., Bolzacchini, E., and Ferrero, L.: Seasonal behavior of PM2.5 deliquescence, crystallization, and hygroscopic growth in the Po Valley (Milan): Implications for remote sensing applications, Atmos. Res., 176-177, 87–95, https://doi.org/10.1016/j.atmosres.2016.02.011, 2016. a, b, c, d
Decesari, S., Allan, J., Plass-Duelmer, C., Williams, B. J., Paglione, M., Facchini, M. C., O'Dowd, C., Harrison, R. M., Gietl, J. K., Coe, H., Giulianelli, L., Gobbi, G. P., Lanconelli, C., Carbone, C., Worsnop, D., Lambe, A. T., Ahern, A. T., Moretti, F., Tagliavini, E., Elste, T., Gilge, S., Zhang, Y., and Dall'Osto, M.: Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques, Atmos. Chem. Phys., 14, 12109–12132, https://doi.org/10.5194/acp-14-12109-2014, 2014. a
de Freitas, C. R.: Tourism climatology: evaluating environmental information for decision making and business planning in the recreation and tourism sector, Int. J. Biometeorol., 48, 45–54, https://doi.org/10.1007/s00484-003-0177-z, 2003. a
Della Ceca, L., García Ferreyra, M. F., Lyapustin, A., Chudnovsky, A., Otero, L., Carreras, H., and Barnaba, F.: Satellite-based view of the aerosol spatial and temporal variability in the Córdoba region (Argentina) using over ten years of high-resolution data, ISPRS J. Photogramm., 145, 250–267, https://doi.org/10.1016/j.isprsjprs.2018.08.016, 2018. a
De Wekker, S. F. J., Kossmann, M., Knievel, J. C., Giovannini, L., Gutmann, E. D., and Zardi, D.: Meteorological Applications Benefiting from an Improved Understanding of Atmospheric Exchange Processes over Mountains, Atmosphere, 9, 371, https://doi.org/10.3390/atmos9100371, 2018. a
Dhungel, S., Kathayat, B., Mahata, K., and Panday, A.: Transport of regional pollutants through a remote trans-Himalayan valley in Nepal, Atmos. Chem. Phys., 18, 1203–1216, https://doi.org/10.5194/acp-18-1203-2018, 2018. a
Diémoz, H.: 4-D CTM simulation of aerosol advections from the Po basin to the northwestern Alps, https://doi.org/10.5446/38391, 2018. a
Diémoz, H., Siani, A. M., Casale, G. R., di Sarra, A., Serpillo, B., Petkov, B., Scaglione, S., Bonino, A., Facta, S., Fedele, F., Grifoni, D., Verdi, L., and Zipoli, G.: First national intercomparison of solar ultraviolet radiometers in Italy, Atmos. Meas. Tech., 4, 1689–1703, https://doi.org/10.5194/amt-4-1689-2011, 2011. a
Diémoz, H., Campanelli, M., and Estellés, V.: One Year of Measurements with a POM-02 Sky Radiometer at an Alpine EuroSkyRad Station, J. Meteorol. Soc. Jpn., 92A, 1–16, https://doi.org/10.2151/jmsj.2014-A01, 2014a. a, b, c
Diémoz, H., Siani, A. M., Redondas, A., Savastiouk, V., McElroy, C. T., Navarro-Comas, M., and Hase, F.: Improved retrieval of nitrogen dioxide (NO2) column densities by means of MKIV Brewer spectrophotometers, Atmos. Meas. Tech., 7, 4009–4022, https://doi.org/10.5194/amt-7-4009-2014, 2014b. a
Diémoz, H., Gobbi, G. P., Magri, T., Pession, G., Pittavino, S., Tombolato, I. K. F., Campanelli, M., and Barnaba, F.: Transport of Po Valley aerosol pollution to the northwestern Alps. Part 2: long-term impact on air quality, Atmos. Chem. Phys. Discuss., submitted, 2019. a, b, c, d, e, f, g, h, i
Dionisi, D., Barnaba, F., Diémoz, H., Di Liberto, L., and Gobbi, G. P.: A multiwavelength numerical model in support of quantitative retrievals of aerosol properties from automated lidar ceilometers and test applications for AOT and PM10 estimation, Atmos. Meas. Tech., 11, 6013–6042, https://doi.org/10.5194/amt-11-6013-2018, 2018. a, b, c, d, e, f, g
Dosio, A., Galmarini, S., and Graziani, G.: Simulation of the circulation and related photochemical ozone dispersion in the Po plains (northern Italy): Comparison with the observations of a measuring campaign, J. Geophys. Res., 107, LOP 2–1–LOP 2–24, https://doi.org/10.1029/2000JD000046, 2002. a
EEA: Air Quality in Europe – 2015 Report, Tech. rep., https://doi.org/10.2800/62459, 2015. a
EEA: Air Quality in Europe – 2017 Report, Tech. rep., https://doi.org/10.2800/850018, 2017. a
EMEP: Transboundary particulate matter, photo-oxidants, acidifying and eutrophying components, Tech. rep., MSC-W, CCC and CEIP, 2016. a, b
Emili, E., Lyapustin, A., Wang, Y., Popp, C., Korkin, S., Zebisch, M., Wunderle, S., and Petitta, M.: High spatial resolution aerosol retrieval with MAIAC: Application to mountain regions, J. Geophys. Res., 116, D23211, https://doi.org/10.1029/2011JD016297, 2011. a
E-PROFILE: ALC data, available at: http://data.ceda.ac.uk/badc/eprofile/data/, last access: 7 March 2019. a
Estellés, V., Campanelli, M., Smyth, T. J., Utrillas, M. P., and Martínez-Lozano, J. A.: Evaluation of the new ESR network software for the retrieval of direct sun products from CIMEL CE318 and PREDE POM01 sun-sky radiometers, Atmos. Chem. Phys., 12, 11619–11630, https://doi.org/10.5194/acp-12-11619-2012, 2012. a
EU Commission: Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe, Official Journal of the European Union, L152, 1–44, 2008. a
Federico, S., Torcasio, R. C., Sanò, P., Casella, D., Campanelli, M., Meirink, J. F., Wang, P., Vergari, S., Diémoz, H., and Dietrich, S.: Comparison of hourly surface downwelling solar radiation estimated from MSG–SEVIRI and forecast by the RAMS model with pyranometers over Italy, Atmos. Meas. Tech., 10, 2337–2352, https://doi.org/10.5194/amt-10-2337-2017, 2017. a
Fernald, F. G.: Analysis of atmospheric lidar observations: some comments, Appl. Optics, 23, 652–653, https://doi.org/10.1364/AO.23.000652, 1984. a
Ferrero, L., Perrone, M. G., Petraccone, S., Sangiorgi, G., Ferrini, B. S., Lo Porto, C., Lazzati, Z., Cocchi, D., Bruno, F., Greco, F., Riccio, A., and Bolzacchini, E.: Vertically-resolved particle size distribution within and above the mixing layer over the Milan metropolitan area, Atmos. Chem. Phys., 10, 3915–3932, https://doi.org/10.5194/acp-10-3915-2010, 2010. a
Ferrero, L., Castelli, M., Ferrini, B. S., Moscatelli, M., Perrone, M. G., Sangiorgi, G., D'Angelo, L., Rovelli, G., Moroni, B., Scardazza, F., Mocnik, G., Bolzacchini, E., Petitta, M., and Cappelletti, D.: Impact of black carbon aerosol over Italian basin valleys: high-resolution measurements along vertical profiles, radiative forcing and heating rate, Atmos. Chem. Phys., 14, 9641–9664, https://doi.org/10.5194/acp-14-9641-2014, 2014. a, b
Ferrero, L., Močnik, G., Cogliati, S., Gregorič, A., Colombo, R., and Bolzacchini, E.: Heating Rate of Light Absorbing Aerosols: Time-Resolved Measurements, the Role of Clouds, and Source Identification, Environ. Sci. Technol., 52, 3546–3555, https://doi.org/10.1021/acs.est.7b04320, 2018. a
Finardi, S. and Pellegrini, U.: Systematic analysis of meteorological conditions causing severe urban air pollution episodes in the central Po Valley, in: 9th Int. Conf. on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, available at: http://www.harmo.org/Conferences/proceedings/_Garmisch/publishedSections/6.13.pdf (last access: 28 February 2019), 2004. a
Finardi, S., Silibello, C., D'Allura, A., and Radice, P.: Analysis of pollutants exchange between the Po Valley and the surrounding European region, Urban Clim., 10, 682–702, https://doi.org/10.1016/j.uclim.2014.02.002, 2014. a
Freney, E. J., Sellegri, K., Canonaco, F., Boulon, J., Hervo, M., Weigel, R., Pichon, J. M., Colomb, A., Prévt̂, A. S. H., and Laj, P.: Seasonal variations in aerosol particle composition at the puy-de-Dôme research station in France, Atmos. Chem. Phys., 11, 13047–13059, https://doi.org/10.5194/acp-11-13047-2011, 2011. a
Fuzzi, S., Baltensperger, U., Carslaw, K., Decesari, S., Denier van der Gon, H., Facchini, M. C., Fowler, D., Koren, I., Langford, B., Lohmann, U., Nemitz, E., Pandis, S., Riipinen, I., Rudich, Y., Schaap, M., Slowik, J. G., Spracklen, D. V., Vignati, E., Wild, M., Williams, M., and Gilardoni, S.: Particulate matter, air quality and climate: lessons learned and future needs, Atmos. Chem. Phys., 15, 8217–8299, https://doi.org/10.5194/acp-15-8217-2015, 2015. a
Gariazzo, C., Silibello, C., Finardi, S., Radice, P., Piersanti, A., Calori, G., Cecinato, A., Perrino, C., Nussio, F., Cagnoli, M., Pelliccioni, A., Gobbi, G. P., and Di Filippo, P.: A gas/aerosol air pollutants study over the urban area of Rome using a comprehensive chemical transport model, Atmos. Environ., 41, 7286–7303, https://doi.org/10.1016/j.atmosenv.2007.05.018, 2007. a
Gilardoni, S., Massoli, P., Giulianelli, L., Rinaldi, M., Paglione, M., Pollini, F., Lanconelli, C., Poluzzi, V., Carbone, S., Hillamo, R., Russell, L. M., Facchini, M. C., and Fuzzi, S.: Fog scavenging of organic and inorganic aerosol in the Po Valley, Atmos. Chem. Phys., 14, 6967–6981, https://doi.org/10.5194/acp-14-6967-2014, 2014. a
Gilardoni, S., Massoli, P., Paglione, M., Giulianelli, L., Carbone, C., Rinaldi, M., Decesari, S., Sandrini, S., Costabile, F., Gobbi, G. P., Pietrogrande, M. C., Visentin, M., Scotto, F., Fuzzi, S., and Facchini, M. C.: Direct observation of aqueous secondary organic aerosol from biomass-burning emissions, P. Natl. Acad. Sci. USA, 113, 10013–10018, https://doi.org/10.1073/pnas.1602212113, 2016. a
Gohm, A., Harnisch, F., Vergeiner, J., Obleitner, F., Schnitzhofer, R., Hansel, A., Fix, A., Neininger, B., Emeis, S., and Schäfer, K.: Air Pollution Transport in an Alpine Valley: Results From Airborne and Ground-Based Observations, Bound.-Lay. Meteorol., 131, 441–463, https://doi.org/10.1007/s10546-009-9371-9, 2009. a
Green, D. C., Fuller, G. W., and Baker, T.: Development and validation of the volatile correction model for PM10 – An empirical method for adjusting TEOM measurements for their loss of volatile particulate matter, Atmos. Environ., 43, 2132–2141, https://doi.org/10.1016/j.atmosenv.2009.01.024, 2009. a
Guariso, G. and Volta, M.: Air Quality Integrated Assessment: A European Perspective, Springer, https://doi.org/10.1007/978-3-319-33349-6, 2017. a
Haeffelin, M., Angelini, F., Morille, Y., Martucci, G., Frey, S., Gobbi, G. P., Lolli, S., O'Dowd, C. D., Sauvage, L., Xueref-Rémy, I., Wastine, B., and Feist, D. G.: Evaluation of Mixing-Height Retrievals from Automatic Profiling Lidars and Ceilometers in View of Future Integrated Networks in Europe, Bound.-Lay. Meteorol., 143, 49–75, https://doi.org/10.1007/s10546-011-9643-z, 2012. a
Henne, S., Furger, M., Nyeki, S., Steinbacher, M., Neininger, B., de Wekker, S. F. J., Dommen, J., Spichtinger, N., Stohl, A., and Prévôt, A. S. H.: Quantification of topographic venting of boundary layer air to the free troposphere, Atmos. Chem. Phys., 4, 497–509, https://doi.org/10.5194/acp-4-497-2004, 2004. a
Henne, S., Furger, M., and Prévôt, A. S. H.: Climatology of Mountain Venting–Induced Elevated Moisture Layers in the Lee of the Alps, J. Appl. Meteorol., 44, 620–633, https://doi.org/10.1175/JAM2217.1, 2005. a
Kambezidis, H. and Kaskaoutis, D.: Aerosol climatology over four AERONET sites: An overview, Atmos. Environ., 42, 1892–1906, https://doi.org/10.1016/j.atmosenv.2007.11.013, 2008. a
Kaufman, Y. and Tanré, D.: Algorithm for remote sensing of tropospheric aerosol form MODIS, MODIS ATBD MOD02, 9, 1–85, Tech. rep., 1998. a
Kazadzis, S., Kouremeti, N., Diémoz, H., Gröbner, J., Forgan, B. W., Campanelli, M., Estellés, V., Lantz, K., Michalsky, J., Carlund, T., Cuevas, E., Toledano, C., Becker, R., Nyeki, S., Kosmopoulos, P. G., Tatsiankou, V., Vuilleumier, L., Denn, F. M., Ohkawara, N., Ijima, O., Goloub, P., Raptis, P. I., Milner, M., Behrens, K., Barreto, A., Martucci, G., Hall, E., Wendell, J., Fabbri, B. E., and Wehrli, C.: Results from the Fourth WMO Filter Radiometer Comparison for aerosol optical depth measurements, Atmos. Chem. Phys., 18, 3185–3201, https://doi.org/10.5194/acp-18-3185-2018, 2018. a
Khan, M., Masiol, M., Formenton, G., Di Gilio, A., de Gennaro, G., Agostinelli, C., and Pavoni, B.: Carbonaceous PM2.5 and secondary organic aerosol across the Veneto region (NE Italy), Sci. Total Environ., 542, 172–181, https://doi.org/10.1016/j.scitotenv.2015.10.103, 2016. a
Khatri, P. and Takamura, T.: An Algorithm to Screen Cloud-Affected Data for Sky Radiometer Data Analysis, J. Meteorol. Soc. Jpn., 87, 189–204, https://doi.org/10.2151/jmsj.87.189, 2009. a
Kim, H., Zhang, Q., and Heo, J.: Influence of intense secondary aerosol formation and long-range transport on aerosol chemistry and properties in the Seoul Metropolitan Area during spring time: results from KORUS-AQ, Atmos. Chem. Phys., 18, 7149–7168, https://doi.org/10.5194/acp-18-7149-2018, 2018. a
Klett, J. D.: Lidar inversion with variable backscatter/extinction ratios, Appl. Optics, 24, 1638–1643, https://doi.org/10.1364/AO.24.001638, 1985. a
Lang, M. N., Gohm, A., and Wagner, J. S.: The impact of embedded valleys on daytime pollution transport over a mountain range, Atmos. Chem. Phys., 15, 11981–11998, https://doi.org/10.5194/acp-15-11981-2015, 2015. a
Larsen, B., Gilardoni, S., Stenström, K., Niedzialek, J., Jimenez, J., and Belis, C.: Sources for PM air pollution in the Po Plain, Italy: II. Probabilistic uncertainty characterization and sensitivity analysis of secondary and primary sources, Atmos. Environ., 50, 203–213, https://doi.org/10.1016/j.atmosenv.2011.12.038, 2012. a, b
Lau, W. K., Kim, M.-K., Kim, K.-M., and Lee, W.-S.: Enhanced surface warming and accelerated snow melt in the Himalayas and Tibetan Plateau induced by absorbing aerosols, Environ. Res. Lett., 5, 025204, https://doi.org/10.1088/1748-9326/5/2/025204, 2010. a
Lehner, M. and Rotach, M. W.: Current Challenges in Understanding and Predicting Transport and Exchange in the Atmosphere over Mountainous Terrain, Atmosphere, 9, 276, https://doi.org/10.3390/atmos9070276, 2018. a, b
Lim, Y. B., Seo, J., Kim, J. Y., and Turpin, B. J.: Multiday haze in the East Asia: Transport and chemical aging of hygroscopic particles, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-364, 2018. a
Lyapustin, A., Wang, Y., Laszlo, I., Kahn, R., Korkin, S., Remer, L., Levy, R., and Reid, J. S.: Multiangle implementation of atmospheric correction (MAIAC): 2. Aerosol algorithm, J. Geophys. Res., 116, D03211, https://doi.org/10.1029/2010JD014986, 2011. a
Lyapustin, A., Wang, Y., Laszlo, I., and Korkin, S.: Improved cloud and snow screening in MAIAC aerosol retrievals using spectral and spatial analysis, Atmos. Meas. Tech., 5, 843–850, https://doi.org/10.5194/amt-5-843-2012, 2012. a
Manara, V., Bassi, M., Brunetti, M., Cagnazzi, B., and Maugeri, M.: 1990–2016 surface solar radiation variability and trend over the Piedmont region (northwest Italy), Theor. Appl. Climatol., https://doi.org/10.1007/s00704-018-2521-6, 2018. a
Mélin, F. and Zibordi, G.: Aerosol variability in the Po Valley analyzed from automated optical measurements, Geophy. Res. Lett., 32, L03810, https://doi.org/10.1029/2004GL021787, 2005. a, b, c
Mercalli, L., Castellano, C., Cat Berro, D., and Di Napoli, G.: Atlante climatico della Valle d'Aosta, vol. 2, Società Meteorologica Subalpina, 2003. a
Moroni, B., Castellini, S., Crocchianti, S., Piazzalunga, A., Fermo, P., Scardazza, F., and Cappelletti, D.: Ground-based measurements of long-range transported aerosol at the rural regional background site of Monte Martano (Central Italy), Atmos. Res., 155, 26–36, https://doi.org/10.1016/j.atmosres.2014.11.021, 2015. a
Nakajima, T., Tonna, G., Rao, R., Boi, P., Kaufman, Y., and Holben, B.: Use of sky brightness measurements from ground for remote sensing of particulate polydispersions, Appl. Optics, 35, 2672–2686, https://doi.org/10.1364/AO.35.002672, 1996. a
Neftel, A., Spirig, C., Prévôt, A. S. H., Furger, M., Stutz, J., Vogel, B., and Hjorth, J.: Sensitivity of photooxidant production in the Milan Basin: An overview of results from a EUROTRAC-2 Limitation of Oxidant Production field experiment, J. Geophys. Res., 107, LOP 1–1–LOP 1–10, https://doi.org/10.1029/2001JD001263, 2002. a
Nenes, A., Pandis, S. N., and Pilinis, C.: ISORROPIA: A new thermodynamic equilibrium model for multiphase multicomponent inorganic aerosols, Aquat. Geochem., 4, 123–152, https://doi.org/10.1023/A:1009604003981, 1998. a
Nyeki, S., Eleftheriadis, K., Baltensperger, U., Colbeck, I., Fiebig, M., Fix, A., Kiemle, C., Lazaridis, M., and Petzold, A.: Airborne Lidar and in-situ Aerosol Observations of an Elevated Layer, Leeward of the European Alps and Apennines, Geophys. Res. Lett., 29, 33–1–33–4, https://doi.org/10.1029/2002GL014897, 2002. a, b
Osborne, S. R., Haywood, J. M., and Bellouin, N.: In situ and remote-sensing measurements of the mean microphysical and optical properties of industrial pollution aerosol during ADRIEX, Q. J. Roy. Meteor. Soc., 133, 17–32, https://doi.org/10.1002/qj.92, 2007. a
Patashnick, H. and Rupprecht, E. G.: Continuous PM-10 Measurements Using the Tapered Element Oscillating Microbalance, J. Air Waste Manage., 41, 1079–1083, https://doi.org/10.1080/10473289.1991.10466903, 1991. a
Pletscher, K., Weiss, M., and Moelter, L.: Simultaneous determination of PM fractions, particle number and particle size distribution in high time resolution applying one and the same optical measurement technique, Gefahrst. Reinhalt. L., 76, 425–436, 2016. a
Putaud, J.-P., Dingenen, R. V., Alastuey, A., Bauer, H., Birmili, W., Cyrys, J., Flentje, H., Fuzzi, S., Gehrig, R., Hansson, H., Harrison, R., Herrmann, H., Hitzenberger, R., Häglin, C., Jones, A., Kasper-Giebl, A., Kiss, G., Kousa, A., Kuhlbusch, T., Löschau, G., Maenhaut, W., Molnar, A., Moreno, T., Pekkanen, J., Perrino, C., Pitz, M., Puxbaum, H., Querol, X., Rodriguez, S., Salma, I., Schwarz, J., Smolik, J., Schneider, J., Spindler, G., ten Brink, H., Tursic, J., Viana, M., Wiedensohler, A., and Raes, F.: A European aerosol phenomenology – 3: Physical and chemical characteristics of particulate matter from 60 rural, urban, and kerbside sites across Europe, Atmos. Environ., 44, 1308–1320, https://doi.org/10.1016/j.atmosenv.2009.12.011, 2010. a, b
Rampanelli, G., Zardi, D., and Rotunno, R.: Mechanisms of Up-Valley Winds, J. Atmos. Sci., 61, 3097–3111, https://doi.org/10.1175/JAS-3354.1, 2004. a
Raut, J.-C. and Chazette, P.: Assessment of vertically-resolved PM10 from mobile lidar observations, Atmos. Chem. Phys., 9, 8617–8638, https://doi.org/10.5194/acp-9-8617-2009, 2009. a
Remer, L. A., Mattoo, S., Levy, R. C., and Munchak, L. A.: MODIS 3 km aerosol product: algorithm and global perspective, Atmos. Meas. Tech., 6, 1829–1844, https://doi.org/10.5194/amt-6-1829-2013, 2013. a
Rosati, B., Gysel, M., Rubach, F., Mentel, T. F., Goger, B., Poulain, L., Schlag, P., Miettinen, P., Pajunoja, A., Virtanen, A., Klein Baltink, H., Henzing, J. S. B., Größ, J., Gobbi, G. P., Wiedensohler, A., Kiendler-Scharr, A., Decesari, S., Facchini, M. C., Weingartner, E., and Baltensperger, U.: Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns, Atmos. Chem. Phys., 16, 7295–7315, https://doi.org/10.5194/acp-16-7295-2016, 2016. a, b
Saarikoski, S., Carbone, S., Decesari, S., Giulianelli, L., Angelini, F., Canagaratna, M., Ng, N. L., Trimborn, A., Facchini, M. C., Fuzzi, S., Hillamo, R., and Worsnop, D.: Chemical characterization of springtime submicrometer aerosol in Po Valley, Italy, Atmos. Chem. Phys., 12, 8401–8421, https://doi.org/10.5194/acp-12-8401-2012, 2012. a, b
Schaap, M., van Loon, M., ten Brink, H. M., Dentener, F. J., and Builtjes, P. J. H.: Secondary inorganic aerosol simulations for Europe with special attention to nitrate, Atmos. Chem. Phys., 4, 857–874, https://doi.org/10.5194/acp-4-857-2004, 2004. a, b
Schmidli, J.: Daytime Heat Transfer Processes over Mountainous Terrain, J. Atmos. Sci., 70, 4041–4066, https://doi.org/10.1175/JAS-D-13-083.1, 2013. a
Schnitzhofer, R., Norman, M., Wisthaler, A., Vergeiner, J., Harnisch, F., Gohm, A., Obleitner, F., Fix, A., Neininger, B., and Hansel, A.: A multimethodological approach to study the spatial distribution of air pollution in an Alpine valley during wintertime, Atmos. Chem. Phys., 9, 3385–3396, https://doi.org/10.5194/acp-9-3385-2009, 2009. a
Serafin, S. and Zardi, D.: Daytime Heat Transfer Processes Related to Slope Flows and Turbulent Convection in an Idealized Mountain Valley, J. Atmos. Sci., 67, 3739–3756, https://doi.org/10.1175/2010JAS3428.1, 2010. a
Serafin, S., Adler, B., Cuxart, J., De Wekker, S. F. J., Gohm, A., Grisogono, B., Kalthoff, N., Kirshbaum, D. J., Rotach, M. W., Schmidli, J., Stiperski, I., Večenaj, Ž., and Zardi, D.: Exchange Processes in the Atmospheric Boundary Layer Over Mountainous Terrain, Atmosphere, 9, 102, https://doi.org/10.3390/atmos9030102, 2018. a
Siani, A. M., Modesti, S., Casale, G. R., Diémoz, H., and Colosimo, A.: Biologically effective surface UV climatology at Rome and Aosta, Italy, AIP Conf. Proc., 1531, 903–906, https://doi.org/10.1063/1.4804917, 2013. a
Siani, A. M., Frasca, F., Scarlatti, F., Religi, A., Diémoz, H., Casale, G. R., Pedone, M., and Savastiouk, V.: Examination on total ozone column retrievals by Brewer spectrophotometry using different processing software, Atmos. Meas. Tech., 11, 5105–5123, https://doi.org/10.5194/amt-11-5105-2018, 2018. a
Silibello, C., Calori, G., Brusasca, G., Giudici, A., Angelino, E., Fossati, G., Peroni, E., and Buganza, E.: Modelling of PM10 concentrations over Milano urban area using two aerosol modules, Environ. Modell. Softw., 23, 333–343, https://doi.org/10.1016/j.envsoft.2007.04.002, 2008. a
Sokhi, R., Kitwiroon, N., and Luhana, L.: FUMAPEX Datasets of Urban Air Pollution Models and Meteorological Preprocessors, in: Fumapex Report D, vol. 2, 1–D2, 2003. a
Sprenger, M. and Wernli, H.: The LAGRANTO Lagrangian analysis tool – version 2.0, Geosci. Model Dev., 8, 2569–2586, https://doi.org/10.5194/gmd-8-2569-2015, 2015. a
Straif, K., Cohen, A., and Samet, J. (Eds.): Air pollution and cancer, WHO Press, World Health Organization, 2013. a
Tampieri, F., Trombetti, F., and Scarani, C.: Summer daily circulation in the Po Valley, Italy, Geophys. Astro. Fluid, 17, 97–112, https://doi.org/10.1080/03091928108243675, 1981. a
Thyer, N. H.: A theoretical explanation of mountain and valley winds by a numerical method, Archiv für Meteorologie, Geophysik und Bioklimatologie, Serie A, 15, 318–348, https://doi.org/10.1007/BF02247220, 1966. a
Turpin, B. J. and Lim, H.-J.: Species Contributions to PM2.5 Mass Concentrations: Revisiting Common Assumptions for Estimating Organic Mass, Aerosol Sci. Tech., 35, 602–610, https://doi.org/10.1080/02786820152051454, 2001. a
Uchino, O., Sakai, T., Izumi, T., Nagai, T., Morino, I., Yamazaki, A., Deushi, M., Yumimoto, K., Maki, T., Tanaka, T. Y., Akaho, T., Okumura, H., Arai, K., Nakatsuru, T., Matsunaga, T., and Yokota, T.: Lidar detection of high concentrations of ozone and aerosol transported from northeastern Asia over Saga, Japan, Atmos. Chem. Phys., 17, 1865–1879, https://doi.org/10.5194/acp-17-1865-2017, 2017. a
Van Donkelaar, A., Martin, R. V., Brauer, M., Kahn, R., Levy, R., Verduzco, C., and Villeneuve, P. J.: Global estimates of ambient fine particulate matter concentrations from satellite-based aerosol optical depth: development and application, Environ. Health Persp., 118, 847, https://doi.org/10.1289/ehp.0901623, 2010. a
Vuillermoz, M., Berlier, F., Borlino, M. C., Crea, D., Tartin, C., and Tibone, C.: Influence of vertical temperature gradients on outdoor sound propagation in a narrow valley, in: AIA-DAGA 2013 proceedings of the International Conference on Acoustics, 18–21 March 2013, Merano, Italy, 2013. a
Wagner, J. S., Gohm, A., and Rotach, M. W.: The impact of valley geometry on daytime thermally driven flows and vertical transport processes, Q. J. Roy. Meteor. Soc., 141, 1780–1794, https://doi.org/10.1002/qj.2481, 2014. a
Weissmann, M., Braun, F. J., Gantner, L., Mayr, G. J., Rahm, S., and Reitebuch, O.: The Alpine Mountain–Plain Circulation: Airborne Doppler Lidar Measurements and Numerical Simulations, Mon. Weather Rev., 133, 3095–3109, https://doi.org/10.1175/MWR3012.1, 2005. a
WHO: Ambient air pollution: a global assessment of exposure and burden of disease, Tech. rep., 2016. a
Wiegner, M. and Gasteiger, J.: Correction of water vapor absorption for aerosol remote sensing with ceilometers, Atmos. Meas. Tech., 8, 3971–3984, https://doi.org/10.5194/amt-8-3971-2015, 2015. a
Wiegner, M. and Geiß, A.: Aerosol profiling with the Jenoptik ceilometer CHM15kx, Atmos. Meas. Tech., 5, 1953–1964, https://doi.org/10.5194/amt-5-1953-2012, 2012. a, b
WMO: WMO/IGAC Impacts of megacities on air pollution and climate, Tech. rep., World Meteorological Organization, available at: https://library.wmo.int/pmb_ged/gaw_205.pdf (last access: 28 February 2019), 2012. a, b
Wotawa, G., Kröger, H., and Stohl, A.: Transport of ozone towards the Alps – results from trajectory analyses and photochemical model studies, Atmos. Environ., 34, 1367–1377, https://doi.org/10.1016/S1352-2310(99)00363-5, 2000. a
Wyngaard, J. C.: Toward Numerical Modeling in the “Terra Incognita”, J. Atmos. Sci., 61, 1816–1826, https://doi.org/10.1175/1520-0469(2004)061<1816:TNMITT>2.0.CO;2, 2004. a
Zeng, Z., Chen, A., Ciais, P., Li, Y., Li, L. Z. X., Vautard, R., Zhou, L., Yang, H., Huang, M., and Piao, S.: Regional air pollution brightening reverses the greenhouse gases induced warming-elevation relationship, Geophys. Res. Lett., 42, 4563–4572, https://doi.org/10.1002/2015GL064410, 2015. a
Zhang, Q., Jiang, X., Tong, D., Davis, S. J., Zhao, H., Geng, G., Feng, T., Zheng, B., Lu, Z., Streets, D. G., Ni, R., Brauer, M., van Donkelaar, A., Martin, R. V., Huo, H., Liu, Z., Pan, D., Kan, H., Yan, Y., Lin, J., He, K., and Guan, D.: Transboundary health impacts of transported global air pollution and international trade, Nature, 543, 705–709, https://doi.org/10.1038/nature21712, 2017. a
Zuev, V. V., Burlakov, V. D., Nevzorov, A. V., Pravdin, V. L., Savelieva, E. S., and Gerasimov, V. V.: 30-year lidar observations of the stratospheric aerosol layer state over Tomsk (Western Siberia, Russia), Atmos. Chem. Phys., 17, 3067–3081, https://doi.org/10.5194/acp-17-3067-2017, 2017. a
|
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 9, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "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": 0.8191956281661987, "perplexity": 6493.581724909275}, "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-2019-22/segments/1558232258058.61/warc/CC-MAIN-20190525124751-20190525150751-00201.warc.gz"}
|
https://zenhax.com/viewtopic.php?f=13&t=556&start=340
|
# ZenHAX
Free Game Research Forum | Official QuickBMS support | twitter @zenhax | SSL HTTPS://zenhax.com
It is currently Wed Jun 03, 2020 4:51 pm
All times are UTC
Post new topic Reply to topic Page 18 of 21 [ 417 posts ] Go to page Previous 1 … 16 17 18 19 20 21 Next
Print view Previous topic | Next topic
Author Message
PostPosted: Sat Dec 15, 2018 5:49 pm
Joined: Sun Aug 17, 2014 5:50 pm
Posts: 24
Code:
input text: "\b\l\a\h\-(\\)"slog NAME 0 SIZEoutput result: \\b\\l\\a\\h\\-(\\\\)
Top
PostPosted: Sat Dec 15, 2018 5:55 pm
Joined: Wed Jul 30, 2014 9:32 pm
Posts: 11349
It seems all correct and the backslashes have been correctly escaped.
Slog creates escaped strings because often the strings contain line feeds, for example with multi-line dialogs.
Top
PostPosted: Wed Mar 13, 2019 9:32 am
Joined: Thu Aug 07, 2014 10:28 pm
Posts: 285
I am having a problem with findloc
quickbms_4gb_files.exe -p dissidia.bms process://dffnt.exe c:\output
I don't think findloc can scan 64bit processes.
if I use this code
findloc OFFSET string "GMPK1"
print "%OFFSET%"
it never finds a value
and if I manually do this
set TMP longlong 0x297ab9c0000
print "%TMP%"
goto TMP
savepos TMP
print "%TMP%"
1st result 2850442444800
2nd result
-1415839744
Top
PostPosted: Wed Mar 13, 2019 10:35 am
Joined: Wed Jul 30, 2014 9:32 pm
Posts: 11349
quickbms and quickbms_4gb_files are 32bit tools, therefore they can't access 64bit processes.
I will never release a 64bit version of the tools because the first requirement is maintaining compatibility with any older OS and system.
Top
PostPosted: Thu Mar 14, 2019 12:18 am
Joined: Fri Aug 08, 2014 1:06 am
Posts: 682
longlong doesn't seem work with the "put" command either.
_________________
Top
PostPosted: Thu Mar 14, 2019 5:32 am
Joined: Wed Jul 30, 2014 9:32 pm
Posts: 11349
you need to use quickbms_4gb_files.exe for 64bit fields.
Just tested and the output is correct.
Top
PostPosted: Mon Apr 08, 2019 2:57 pm
Joined: Wed Jul 30, 2014 9:32 pm
Posts: 11349
I just noticed that tcc (the embedded C compiler) is crashing, I'm investigating what's causing this issue.
Update: ok it was my fault (sort of), everything works perfectly
Top
PostPosted: Sat Apr 13, 2019 2:58 pm
Joined: Sun Mar 04, 2018 1:29 am
Posts: 67
I encountered this error when transferring the .fsh file to .pvr, the script is attached below. Thanks!
Code:
-------------------*EXCEPTION HANDLER*-------------------An error or crash occurred:*EH* ExceptionCode 80000001 guard page violation*EH* ExceptionFlags 00000000*EH* ExceptionAddress 74C7A990 74BF0000 + 0008a990 msvcrt.dll*EH* NumberParameters 00000002*EH* 00000000*EH* 063D3000
_________________
Cryptography - Encryption
Top
PostPosted: Sat Apr 13, 2019 5:06 pm
Joined: Wed Jul 30, 2014 9:32 pm
Posts: 11349
good bug, it's related to the c_structs feature and freeing some old pointers.
use math in your script at line 25 and 28 and it will work
Top
PostPosted: Sun Apr 14, 2019 3:38 am
Joined: Sun Mar 04, 2018 1:29 am
Posts: 67
Sorry, but this is not my specialty.
Can you elaborate on this issue?
Thanks!
Code:
if format = 99 ofmt = 6 endif if format = 100 ofmt = 2 endif
_________________
Cryptography - Encryption
Top
PostPosted: Sun Apr 14, 2019 9:02 am
Joined: Wed Jul 30, 2014 9:32 pm
Posts: 11349
Code:
if format = 99 math ofmt = 6 endif if format = 100 math ofmt = 2 endif
Top
PostPosted: Mon Apr 22, 2019 9:35 pm
Joined: Mon Apr 22, 2019 9:30 pm
Posts: 2
So I am trying to unpack the pak file for Friday the 13th: The Game to see in umodel. But when trying to unpack the file, I get this:
Code:
- open input file C:\Users\Ben\Desktop\F13\SummerCamp-WindowsNoEditor.pak- open script unreal_tournament_4.bms- set output folder . offset filesize filename--------------------------------------- error in src\extra\xalloc.c line 703: xdbg_realloc()Error: memory allocation problem Access is denied.
Top
PostPosted: Wed Apr 24, 2019 6:30 am
Joined: Wed Apr 24, 2019 6:27 am
Posts: 1
Can someone explain what this error means?
Thanks
- GUI mode activated, remember that the tool works also from command-line
where are available various options like folder scanning, filters and so on
- select the BMS script to use
- select the input archives/files to extract, type * or "" for whole folder and subfolders
- select the output folder where extracting the files
- open input file C:\Users\user\Desktop\files\GEARASSETS_NOO_ScriptAssets.xxx
- open script C:\Users\user\Desktop\Injustice2_model\ue3_oodle.bms
- set output folder C:\Users\user\Desktop\files\end
offset filesize filename
--------------------------------------
+ 00000000 104 GEARASSETS_NOO_ScriptAssets.unp
+ 00001868 4294967207 GEARASSETS_NOO_ScriptAssets.unp
Error: impossible to write 0xffffffa7 bytes (total 0xffffffa7)
Last script line before the error or that produced the error:
Press ENTER or close the window to quit
Top
PostPosted: Wed Apr 24, 2019 5:51 pm
Joined: Thu Aug 07, 2014 10:28 pm
Posts: 285
Top
PostPosted: Wed Apr 24, 2019 9:13 pm
Joined: Mon Apr 22, 2019 9:30 pm
Posts: 2
chrrox wrote:
No, it isn't. There is still a good amount of GB left in my C: Drive and D: Drive. Is there a certain amount of GB required to unpack the file?
Top
PostPosted: Thu Apr 25, 2019 3:27 pm
Joined: Thu Apr 25, 2019 2:52 pm
Posts: 3
Code:
-------------------*EXCEPTION HANDLER*-------------------An error or crash occurred:*EH* ExceptionCode 80000001 guard page violation*EH* ExceptionFlags 00000000*EH* ExceptionAddress 01078452 01050000 + 00028452 quickbms.exe*EH* NumberParameters 00000002*EH* 00000000*EH* 106B1270Last script line before the error or that produced the error: 229 clog NAME OFFSET ZSIZE SIZE
SLZ.bms
Top
PostPosted: Fri Apr 26, 2019 5:11 am
Joined: Wed Jul 30, 2014 9:32 pm
Posts: 11349
@Scott Rash
off-topic, there is the UE4 topic viewtopic.php?f=9&t=1005
off-topic, since it's a game/script thing.
that error means that the size field is invalid 0xffffffa7, the script must be updated
@z22901206
probably off-topic but I will check
Top
PostPosted: Fri Apr 26, 2019 11:34 am
Joined: Wed Jul 30, 2014 9:32 pm
Posts: 11349
@z22901206
I'm still not sure if it's a bug of the algorithm or it's related to the invalid decompressed size field specified in the archive.
Anyway, I have added a check on the end of the input data in the algorithm and now it works, it will be available in quickbms 0.10.0
Top
PostPosted: Sun Apr 28, 2019 6:26 am
Joined: Wed Jul 30, 2014 9:32 pm
Posts: 11349
QuickBMS 0.10.0 is out
Top
PostPosted: Sun Apr 28, 2019 10:19 am
Joined: Sat Sep 15, 2018 5:22 am
Posts: 275
reimport mode full support for multiple reversed math operators
operators are maximum?
and whats different between quickbms.exe and quickbms_4gb_files.exe? except bigger than 4 gigabyte or 64-bit files? can use quickbms_4gb_files.exe always? so whay there is two exe always? quickbms_4gb_files.exe wants more CPU or more memory ram? is this the reason? or anything else?
Top
Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
Post new topic Reply to topic Page 18 of 21 [ 417 posts ] Go to page Previous 1 … 16 17 18 19 20 21 Next
All times are UTC
You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum
Search for:
|
{"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": 0.3720378577709198, "perplexity": 28296.424806699462}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "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-2020-24/segments/1590347435238.60/warc/CC-MAIN-20200603144014-20200603174014-00569.warc.gz"}
|
https://www.ni.com/documentation/en/labview/latest/analysis-node-ref/histogram-arbitrary-bins/
|
Histogram (Arbitrary Bins) (G Dataflow)
Finds the discrete histogram of a signal based on the given bin specifications.
signal
The input signal.
bins
Boundaries of each bin of the histogram. This input is an array of clusters where each cluster defines the range of values for a bin.
If no bin specifications are provided in bins, this node uses maximum, minimum, number of bins, and inclusion to specify a set of uniformly spaced bins.
lower
Lower boundaries of the bin.
Default: 0
upper
Upper boundaries of the bin.
Default: 0
inclusion
Method to treat the boundaries of each bin.
Name Description
lower Includes the lower boundary.
upper Includes the upper boundary.
both Includes both boundaries.
neither Includes neither boundaries.
Default: lower
maximum
Maximum value to include in the histogram.
Default: 0
minimum
Minimum value to include in the histogram.
Default: 0
error in
Error conditions that occur before this node runs.
The node responds to this input according to standard error behavior.
Standard Error Behavior
Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.
error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.
If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.
If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.
Default: No error
number of bins
Number of bins in the histogram.
Default: 10
inclusion
The boundary of each bin to handle.
If bin specifications are provided in bins, this node uses the inclusion in bins instead.
Name Description
lower
Includes the lower boundary.
upper
Includes the upper boundary.
Determining the Bin Widths When inclusion Is lower
If inclusion is set to lower, the bin widths are determined according to the following equations.
${\mathrm{\Delta }}_{0}=\left[\mathrm{min},\text{\hspace{0.17em}}\mathrm{min}+\mathrm{\Delta }x\right)$
${\mathrm{\Delta }}_{1}=\left[\mathrm{min}+\mathrm{\Delta }x,\text{\hspace{0.17em}}\mathrm{min}+2\mathrm{\Delta }x\right)$
$⋮$
${\mathrm{\Delta }}_{i}=\left[\mathrm{min}+i\mathrm{\Delta }x,\text{\hspace{0.17em}}\mathrm{min}+\left(i+1\right)\mathrm{\Delta }x\right)$
$⋮$
${\mathrm{\Delta }}_{k-1}=\left[\mathrm{min}+\left(k-1\right)\mathrm{\Delta }x,\text{\hspace{0.17em}}\mathrm{max}\right]$
where
• $\mathrm{\Delta }x=\frac{\mathrm{max}-\mathrm{min}}{m}$
• max is the maximum
• min is the minimum
• m is the number of bins
Determining the Bin Widths When inclusion Is upper
If inclusion is set to upper, the bin widths are determined according to the following equations.
${\mathrm{\Delta }}_{0}=\left[\mathrm{min},\text{\hspace{0.17em}}\mathrm{min}+\mathrm{\Delta }x\right]$
${\mathrm{\Delta }}_{1}=\left(\mathrm{min}+\mathrm{\Delta }x,\text{\hspace{0.17em}}\mathrm{min}+2\mathrm{\Delta }x\right]$
$⋮$
${\mathrm{\Delta }}_{i}=\left(\mathrm{min}+i\mathrm{\Delta }x,\text{\hspace{0.17em}}\mathrm{min}+\left(i+1\right)\mathrm{\Delta }x\right]$
$⋮$
${\mathrm{\Delta }}_{k-1}=\left(\mathrm{min}+\left(k-1\right)\mathrm{\Delta }x,\text{\hspace{0.17em}}\mathrm{max}\right]$
where
• $\mathrm{\Delta }x=\frac{\mathrm{max}-\mathrm{min}}{m}$
• max is the maximum
• min is the minimum
• m is the number of bins
Default: lower
histogram graph
The histogram of the input signal.
x values
An array of the center values of the bins of the histogram.
histogram h(x)
Discrete histogram of the input signal.
histogram h(x)
Discrete histogram of the input signal.
x values
An array of the center values of the bins of the histogram.
samples outside
Information about points that do not fall in any bin upon successful execution of the node.
total
Total number of values in signal that do not fall in any bin upon successful execution.
below
Number of values in signal below the first bin on the lower boundary.
above
Number of values in signal above the last bin on the upper boundary.
error out
Error information.
The node produces this output according to standard error behavior.
Standard Error Behavior
Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.
error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.
If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.
If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.
Algorithm for Obtaining the Histogram
The node completes the following steps to obtain the histogram h(x):
1. Establishes all the bins, which are the intervals, based on the information in bins.
2. Defines the function yi(x).
3. Evaluates histogram h(x).
Algorithm for Calculating the Bin Intervals
The following equation defines the bin intervals.
${\mathrm{\Delta }}_{i}=\left(\mathrm{bins}\left[i\right].\mathrm{lower}:\mathrm{bins}\left[i\right].\mathrm{upper}\right)\text{\hspace{0.17em}}\text{for}\text{\hspace{0.17em}}i=0,\text{\hspace{0.17em}}1,\text{\hspace{0.17em}}2,\text{\hspace{0.17em}}...,\text{\hspace{0.17em}}k-1$
where
• bins[i].lower is the value lower in the ith cluster of array bins
• bins[i].upper is the value upper in the ith cluster of array bins
• k is the number of elements in bins, which consists of the number of total bins
Whether the two ending points bins[i].lower and bins[i].upper of each bin are included in the bin ${\mathrm{\Delta }}_{i}$ depends on the value of inclusion in the corresponding cluster i of bins.
If bins is an empty array, this node uses the inputs maximum, minimum, and number of bins to establish the bins. Each bin width $\mathrm{\Delta }x$ is the same and calculated with the following equation.
The following equation calculates the width of the frequency bin Δx.
$\mathrm{\Delta }x=\frac{\mathrm{max}-\mathrm{min}}{m}$
where
• max is maximum
• min is minimum
• m is number of bins
Algorithm for Defining the Function yi(x)
The following equation defines the function yi(x).
${y}_{i}\left(x\right)=\left\{\begin{array}{c}1\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{if}\text{\hspace{0.17em}}x\in {\mathrm{\Delta }}_{i}\\ 0\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{elsewhere}\end{array}$
Algorithm for Evaluating the Histogram
This node evaluates the histogram h(x) with the following equation.
${h}_{i}=\sum _{j=0}^{n-1}{y}_{i}\left({x}_{j}\right)$
where
• n is the number of elements in the input signal
• hi is the total number of points in the input signal that fall into the bin ${\mathrm{\Delta }}_{i}$
• i = 0, 1, ..., k - 1
• k is number of bins
Where This Node Can Run:
Desktop OS: Windows
FPGA: Not supported
Web Server: Not supported in VIs that run in a web application
|
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 21, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "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": 0.7458606958389282, "perplexity": 2129.296688882595}, "config": {"markdown_headings": false, "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/1610704835583.91/warc/CC-MAIN-20210128005448-20210128035448-00469.warc.gz"}
|
https://stats.libretexts.org/Courses/Fresno_City_College/Book%3A_Business_Statistics_Customized_(OpenStax)/Using_Excel_Spreadsheets_in_Statistics/3_Discrete_Probability/3.6_Geometric_Probability_using_the_Excel_Sheet_provided
|
# 3.6 Geometric Probability using the Excel Sheet provided
$$\newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} }$$ $$\newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}}$$$$\newcommand{\id}{\mathrm{id}}$$ $$\newcommand{\Span}{\mathrm{span}}$$ $$\newcommand{\kernel}{\mathrm{null}\,}$$ $$\newcommand{\range}{\mathrm{range}\,}$$ $$\newcommand{\RealPart}{\mathrm{Re}}$$ $$\newcommand{\ImaginaryPart}{\mathrm{Im}}$$ $$\newcommand{\Argument}{\mathrm{Arg}}$$ $$\newcommand{\norm}[1]{\| #1 \|}$$ $$\newcommand{\inner}[2]{\langle #1, #2 \rangle}$$ $$\newcommand{\Span}{\mathrm{span}}$$ $$\newcommand{\id}{\mathrm{id}}$$ $$\newcommand{\Span}{\mathrm{span}}$$ $$\newcommand{\kernel}{\mathrm{null}\,}$$ $$\newcommand{\range}{\mathrm{range}\,}$$ $$\newcommand{\RealPart}{\mathrm{Re}}$$ $$\newcommand{\ImaginaryPart}{\mathrm{Im}}$$ $$\newcommand{\Argument}{\mathrm{Arg}}$$ $$\newcommand{\norm}[1]{\| #1 \|}$$ $$\newcommand{\inner}[2]{\langle #1, #2 \rangle}$$ $$\newcommand{\Span}{\mathrm{span}}$$
Suppose the probability that a red car enters an intersection is 0.24. What is the likelihood that the first red car enters the intersection after four non-red vehicles pass through the intersection? The discrete probability distribution is Geometric.
P(Red Car) = .24
P(Not Red Car) = 1-.24 = .76
P( X = 5) = (.76)4(.24) =
To compute the probability in the Excel spreadsheet provided, enter the following.
3.6 Geometric Probability using the Excel Sheet provided is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.
|
{"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": 1, "mathjax_asciimath": 0, "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": 0.939601719379425, "perplexity": 1148.794200965287}, "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-2022-27/segments/1656103671290.43/warc/CC-MAIN-20220630092604-20220630122604-00028.warc.gz"}
|
https://www.core-econ.org/doing-economics/book/text/01-03.html
|
# Empirical Project 1 Working in R
Don’t forget to also download the data into your working directory by following the steps in this project.
## Getting started in R
If you have worked with R and have the software installed on your machine, you can begin this project. If you have not, watch the videos ‘Installing R and RStudio’ and ‘RStudio orientation’ for guidance on installing and using RStudio.
## Part 1.1 The behaviour of average surface temperature over time
### Learning objectives for this part
• use line charts to describe the behaviour of real-world variables over time.
In the questions below, we look at data from NASA about land–ocean temperature anomalies in the northern hemisphere. Figure 1.1 is constructed using this data, and shows temperatures in the northern hemisphere over the period 1880–2016, expressed as differences from the average temperature from 1951 to 1980. We start by creating charts similar to Figure 1.1, in order to visualize the data and spot patterns more easily.
Figure 1.1 Northern hemisphere temperatures (1880–2016).
Before plotting any charts, download the data and make sure you understand how temperature is measured:
• Go to NASA’s Goddard Institute for Space Studies website.
• Under the subheading ‘Combined Land-Surface Air and Sea-Surface Water Temperature Anomalies’, select the CSV version of ‘Northern Hemisphere-mean monthly, seasonal, and annual means’ (right-click and select ‘Save Link As…’).
• The default name of this file is NH.Ts+dSST.csv. Give it a suitable name and save it in an easily accessible location, such as a folder on your Desktop or in your personal folder.
1. In this dataset, temperature is measured as ‘anomalies’ rather than as absolute temperature. Using NASA’s Frequently Asked Questions section as a reference, explain in your own words what temperature ‘anomalies’ means. Why have researchers chosen this particular measure over other measures (such as absolute temperature)?
First we have to import the data into R.
### R walk-through 1.1 Importing the datafile into R
We want to import the datafile called ‘NH.Ts+dSST.csv’ into R.
We start by setting our working directory using the setwd command. This command tells R where your datafiles are stored. In the code below, replace ‘YOURFILEPATH’ with the full filepath that indicates the folder in which you have saved the datafile. If you don’t know how to find the path to your working folder, see the ‘Technical Reference’ section.
setwd("YOURFILEPATH")
Since our data is in csv format, we use the read.csv function to import the data into R. We will call our file ‘tempdata’ (short for ‘temperature data’).
Here you can see commands to R which are spread across two lines. You can spread a command across multiple lines, but you must adhere to the following two rules for this to work. First, the line break should come inside a set of parenthesis (i.e. between ( and ) or straight after the assignment operator (<-). Second, the line break must not be inside a string (whatever is inside quotes) or in the middle of a word or number.
tempdata <- read.csv("NH.Ts+dSST.csv",
skip = 1, na.strings = "***")
When using this function, we added two options. If you open the spreadsheet in Excel, you will see that the real data table only starts in Row 2, so we use the skip = 1 option to skip the first row when importing the data. When looking at the spreadsheet, you can see that missing temperature data is coded as "***". In order for R to recognize the non-missing temperature data as numbers, we use the na.strings = "***" option to indicate that missing observations in the spreadsheet are coded as "***".
To check that the data has been imported correctly, you can use the head function to view the first six rows of the dataset, and confirm that they correspond to the columns in the csv file.
head(tempdata)
## Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov
## 1 1880 -0.57 -0.41 -0.28 -0.38 -0.12 -0.24 -0.25 -0.26 -0.29 -0.34 -0.39
## 2 1881 -0.21 -0.27 -0.01 -0.04 -0.07 -0.38 -0.07 -0.04 -0.25 -0.42 -0.44
## 3 1882 0.21 0.20 -0.01 -0.38 -0.33 -0.39 -0.38 -0.15 -0.18 -0.54 -0.34
## 4 1883 -0.61 -0.70 -0.17 -0.29 -0.34 -0.27 -0.10 -0.27 -0.35 -0.23 -0.42
## 5 1884 -0.24 -0.13 -0.67 -0.64 -0.43 -0.53 -0.49 -0.52 -0.46 -0.42 -0.49
## 6 1885 -1.01 -0.37 -0.21 -0.54 -0.57 -0.49 -0.38 -0.46 -0.33 -0.31 -0.29
## Dec J.D D.N DJF MAM JJA SON
## 1 -0.51 -0.34 NA NA -0.26 -0.25 -0.34
## 2 -0.30 -0.21 -0.23 -0.33 -0.04 -0.16 -0.37
## 3 -0.43 -0.23 -0.22 0.04 -0.24 -0.31 -0.35
## 4 -0.27 -0.34 -0.35 -0.58 -0.27 -0.21 -0.33
## 5 -0.40 -0.45 -0.44 -0.22 -0.58 -0.51 -0.45
## 6 0.00 -0.41 -0.45 -0.60 -0.44 -0.44 -0.31
Before working with the important data, we use the str function to check that the data is formatted correctly.
str(tempdata)
## 'data.frame': 138 obs. of 19 variables:
## $Year: int 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 ... ##$ Jan : num -0.57 -0.21 0.21 -0.61 -0.24 -1.01 -0.69 -1.08 -0.54 -0.33 ...
## $Feb : num -0.41 -0.27 0.2 -0.7 -0.13 -0.37 -0.69 -0.6 -0.61 0.32 ... ##$ Mar : num -0.28 -0.01 -0.01 -0.17 -0.67 -0.21 -0.58 -0.37 -0.59 0.05 ...
## $Apr : num -0.38 -0.04 -0.38 -0.29 -0.64 -0.54 -0.35 -0.43 -0.26 0.12 ... ##$ May : num -0.12 -0.07 -0.33 -0.34 -0.43 -0.57 -0.36 -0.28 -0.18 -0.07 ...
## $Jun : num -0.24 -0.38 -0.39 -0.27 -0.53 -0.49 -0.44 -0.21 -0.06 -0.15 ... ##$ Jul : num -0.25 -0.07 -0.38 -0.1 -0.49 -0.38 -0.21 -0.23 0.01 -0.12 ...
## $Aug : num -0.26 -0.04 -0.15 -0.27 -0.52 -0.46 -0.48 -0.53 -0.21 -0.19 ... ##$ Sep : num -0.29 -0.25 -0.18 -0.35 -0.46 -0.33 -0.35 -0.18 -0.15 -0.28 ...
## $Oct : num -0.34 -0.42 -0.54 -0.23 -0.42 -0.31 -0.33 -0.41 0.01 -0.37 ... ##$ Nov : num -0.39 -0.44 -0.34 -0.42 -0.49 -0.29 -0.46 -0.21 -0.04 -0.63 ...
## $Dec : num -0.51 -0.3 -0.43 -0.27 -0.4 0 -0.18 -0.45 -0.28 -0.58 ... ##$ J.D : num -0.34 -0.21 -0.23 -0.34 -0.45 -0.41 -0.43 -0.42 -0.24 -0.19 ...
## $D.N : num NA -0.23 -0.22 -0.35 -0.44 -0.45 -0.41 -0.39 -0.26 -0.16 ... ##$ DJF : num NA -0.33 0.04 -0.58 -0.22 -0.6 -0.46 -0.62 -0.53 -0.1 ...
## $MAM : num -0.26 -0.04 -0.24 -0.27 -0.58 -0.44 -0.43 -0.36 -0.34 0.03 ... ##$ JJA : num -0.25 -0.16 -0.31 -0.21 -0.51 -0.44 -0.38 -0.32 -0.09 -0.15 ...
## $SON : num -0.34 -0.37 -0.35 -0.33 -0.45 -0.31 -0.38 -0.27 -0.06 -0.43 ... You can see that all variables are formatted as numerical data (num), so R correctly recognizes that the data are numbers. Now create some line charts using monthly, seasonal, and annual data, which help us look for general patterns over time. 1. Choose one month and plot a line chart with average temperature anomaly on the vertical axis and time (from 1880 to the latest year available) on the horizontal axis. Label each axis appropriately and give your chart a suitable title (Refer to Figure 1.1 as an example.) ### R walk-through 1.2 Drawing a line chart of temperature and time The data is formatted as numerical (num) data, so R recognizes each variable as a series of numbers (instead of text), but does not recognize that these numbers correspond to the same variable for different time periods (known as ‘time series data’ in economics). Letting R know that we have time series data will make coding easier later (especially with making graphs). You can use the ts function to specify that a variable is a time series. Make sure to amend the code below so that the end year (end = c()) corresponds to the latest year in your dataset (our example uses 2017). tempdata$Jan <- ts(tempdata$Jan, start = c(1880), end = c(2017), frequency = 1) tempdata$DJF <- ts(tempdata$DJF, start = c(1880), end = c(2017), frequency = 1) tempdata$MAM <- ts(tempdata$MAM, start = c(1880), end = c(2017), frequency = 1) tempdata$JJA <- ts(tempdata$JJA, start = c(1880), end = c(2017), frequency = 1) tempdata$SON <- ts(tempdata$SON, start = c(1880), end = c(2017), frequency = 1) tempdata$J.D <- ts(tempdata$J.D, start = c(1880), end = c(2017), frequency = 1) Note that we placed each of these quarterly series in the relevant middle month. You could do the same for the remaining series, but we will only use the series above in this R walk-through. We can now use these variables to draw line charts using the plot function. As an example, we will draw a line chart using data for January (tempdata$Jan) for the years 1880–2016. The title option on the next line adds a chart title, and the abline option draws a horizontal line according to our specifications. Make sure to amend the code below so that your chart title corresponds to the latest year in your dataset (our example uses 2016).
# Set line width and colour
plot(tempdata$Jan, type = "l", col = "blue", lwd = 2, ylab = "Annual temperature anomalies", xlab = "Year") # Add a title title("Average temperature anomaly in January in the northern hemisphere (1880-2016)") # Add a horizontal line (at y = 0) abline(h = 0, col = "darkorange2", lwd = 2) # Add a label to the horizontal line text(2000, -0.1, "1951-1980 average") Figure 1.2 Northern hemisphere January temperatures (1880–2016). Try different values for type and col in the plot function to figure out what these options do (some online research could help). xlab and ylab define the respective axis titles. It is important to remember that all axis and chart titles should be enclosed in quotation marks (""), as well as any words that are not options (for example, colour names or filenames). 1. Extra practice: The columns labelled DJF, MAM, JJA, and SON contain seasonal averages (means). For example, the MAM column contains the average of the March, April, and May columns for each year. Plot a separate line chart for each season, using average temperature anomaly for that season on the vertical axis and time (from 1880 to the latest year available) on the horizontal axis. 1. The column labelled J–D contains the average temperature anomaly for each year. • Plot a line chart with annual average temperature anomaly on the vertical axis and time (from 1880 to the latest year available) on the horizontal axis. Your chart should look like Figure 1.1. Extension: Add a horizontal line that intersects the vertical axis at 0, and label it ‘1951–1980 average’. • What do your charts from Questions 2 to 4(a) suggest about the relationship between temperature and time? ### R walk-through 1.3 Producing a line chart for the annual temperature anomalies This is where the power of programming languages becomes evident: to produce the same line chart for a different variable, we simply take the code used in R walk-through 1.2 and replace the variable name Jan with the name for the annual variable (J.D). Again, make sure to amend the code so that your chart title corresponds to the latest year in your data (our example uses 2016). # Set line width and colour plot(tempdata$J.D, type = "l", col = "blue", lwd = 2,
ylab = "Annual temperature anomalies", xlab = "Year")
# \n creates a line break
title("Average annual temperature anomaly \n in the northern hemisphere (1880-2016)")
# Add a horizontal line (at y = 0)
abline(h = 0, col = "darkorange2", lwd = 2)
# Add a label to the horizontal line
text(2000, -0.1, "1951-1980 average")
Figure 1.3 Northern hemisphere annual temperatures (1880–2016).
1. You now have charts for three different time intervals: month (Question 2), season (Question 3), and year (Question 4). For each time interval, discuss what we can learn about patterns in temperature over time that we might not be able to learn from the charts of other time intervals.
1. Compare your chart from Question 4 to Figure 1.4, which also shows the behaviour of temperature over time using data taken from the National Academy of Sciences.
• Discuss the similarities and differences between the charts. (For example, are the horizontal and vertical axes variables the same, or do the lines have the same shape?)
• Looking at the behaviour of temperature over time from 1000 to 1900 in Figure 1.4, are the observed patterns in your chart unusual?
• Based on your answers to Questions 4 and 5, do you think the government should be concerned about climate change?
Figure 1.4 Northern hemisphere temperatures over the long run (1000–2006).
## Part 1.2 Variation in temperature over time
### Learning objectives for this part
• summarize data in a frequency table, and visualize distributions with column charts
• describe a distribution using mean and variance.
Aside from changes in the mean temperature, the government is also worried that climate change will result in more frequent extreme weather events. The island has experienced a few major storms and severe heat waves in the past, both of which caused serious damage and disruption to economic activity.
Will weather become more extreme and vary more as a result of climate change? A New York Times article uses the same temperature dataset you have been using to investigate the distribution of temperatures and temperature variability over time. Read through the article, paying close attention to the descriptions of the temperature distributions.
We can use the mean and median to describe distributions, and we can use deciles to describe parts of distributions. To visualize distributions, we can use column charts (sometimes referred to as frequency histograms). We are now going to create similar charts of temperature distributions to the ones in the New York Times article, and look at different ways of summarizing distributions.
frequency table
A record of how many observations in a dataset have a particular value, range of values, or belong to a particular category.
In order to create a column chart using the temperature data we have, we first need to summarize the data using a frequency table. Instead of using deciles to group the data, we use intervals of 0.05, so that temperature anomalies with a value from −0.3 to −0.25 will be in one group, a value greater than −0.25 and up to 0.2 in another group, and so on. The frequency table shows us how many values belong to a particular group.
1. Using the monthly data for June, July, and August, create two frequency tables similar to Figure 1.5 for the years 1951–1980 and 1981–2010 respectively. The values in the first column should range from −0.3 to 1.05, in intervals of 0.05. See R walk-through 1.3 for how to do this.
Range of temperature anomaly (T) Frequency
−0.30
−0.25
1.00
1.05
Figure 1.5 A frequency table.
1. Using the frequency tables from Question 1:
• Plot two separate column charts (frequency histograms) for 1951–1980 and 1981–2010 to show the distribution of temperatures, with frequency on the vertical axis and the range of temperature anomaly on the horizontal axis. Your charts should look similar to those in the New York Times article.
• Using your charts, describe the similarities and differences (if any) between the distributions of temperature anomalies in 1951–1980 and 1981–2010.
### R walk-through 1.4 Creating frequency tables and histograms
Since we will be looking at data from different subperiods (year intervals) separately, we will create a categorical variable (a variable that has two or more categories) that indicates the subperiod for each observation (row). In R this type of variable is called a ‘factor variable’. When we create a factor variable, we need to define the categories that this variable can take.
tempdata$Period <- factor(NA, levels = c("1921-1950", "1951-1980", "1981-2010"), ordered = TRUE) We created a new variable called Period and defined the possible categories (which R refers to as ‘levels’). Since we will not be using data for some years (before 1921 and after 2010), we want Period to take the value ‘NA’ (not available) for these observations (rows), and the appropriate category for all the other observations (between 1921–2010). One way to do this is by defining Period as ‘NA’ for all observations, then change the values of Period for the observations in 1921–2010. tempdata$Period[(tempdata$Year > 1920) & (tempdata$Year < 1951)] <- "1921-1950"
tempdata$Period[(tempdata$Year > 1950) &
(tempdata$Year < 1981)] <- "1951-1980" tempdata$Period[(tempdata$Year > 1980) & (tempdata$Year < 2011)] <- "1981-2010"
We need to use all monthly anomalies from June, July, and August, but they are currently in three separate columns. We will use the c (combine) function to create one new variable (called temp_summer) that contains all these values.
# Combine the temperature data for June, July, and August
temp_summer <- c(tempdata$Jun, tempdata$Jul, tempdata$Aug) There are many ways to achieve the same result. One alternative is to use the unlist function and apply it to Columns 7 to 9 (containing the data for June to August) of tempdata. temp_summer <- unlist(tempdata[,7:9],use.names = FALSE) Now we have one long variable (temp_summer), with the monthly temperature anomalies for the three months (from 1880 to the latest year) attached to each other. But remember that we want to make separate calculations for each category in Period (1921–1950, 1951–1980, 1981–2010). To make a variable showing the categories for the temp_summer variable, we use the c function again. # Mirror the Period information for temp_sum temp_Period <- c(tempdata$Period, tempdata$Period, tempdata$Period)
# Repopulate the factor information
temp_Period <- factor(temp_Period,
levels = 1:nlevels(tempdata$Period), labels = levels(tempdata$Period))
After using the c function, we had to use the factor function again to tell R that our new variable temp_Period is a factor variable.
We have now created the variables needed to make frequency tables and histograms (temp_summer and temp_Period). To obtain the frequency table for 1951–1980, we use the hist function on the monthly temperature anomalies from the period ‘1951–1980’: temp_summer[(temp_Period == "1951-1980")]. The option plot = FALSE tells R not to make a plot of this information. (See what happens if you set it to TRUE.)
hist(temp_summer[(temp_Period == "1951-1980")],
plot = FALSE)
## $breaks ## [1] -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 ## [12] 0.25 ## ##$counts
## [1] 2 7 6 7 14 6 14 12 10 9 3
##
## $density ## [1] 0.4444444 1.5555556 1.3333333 1.5555556 3.1111111 1.3333333 3.1111111 ## [8] 2.6666667 2.2222222 2.0000000 0.6666667 ## ##$mids
## [1] -0.275 -0.225 -0.175 -0.125 -0.075 -0.025 0.025 0.075 0.125 0.175
## [11] 0.225
##
## $xname ## [1] "temp_summer[(temp_Period == \"1951-1980\")]" ## ##$equidist
## [1] TRUE
##
## attr(,"class")
## [1] "histogram"
From the output you can see that we can get the temperature ranges (the values in $breaks correspond to Column 1 of Figure 1.5) and the frequencies ($counts), which is all we need to create a frequency table. However, in our case the frequency table is merely a temporary input required to produce a histogram.
We can make the three histograms we need all at once, using the histogram function from the mosaic package.
The function below includes multiple commands:
• | temp_Period splits the data according to its category, given by temp_Period.
• type = "count" indicates that we want to display the counts (frequencies) in each category.
• breaks = seq(-0.5, 1.3, 0.1) gives a sequence of numbers −0.5, −0.4, …, 1.3, which are boundaries for the categories.
• main = "Histogram of temperature anomalies" gives Figure 1.6 its title.
# Load the library we use for the following command.
library(mosaic)
histogram(~ temp_summer | temp_Period, type = "count",
breaks = seq(-0.5, 1.3, 0.10),
main = "Histogram of Temperature anomalies",
xlab = "Summer temperature distribution")
Figure 1.6 Summer temperature distributions for different time periods.
To explain what a histogram displays, we refer to the histogram for the period from 1921–1950. Notice the vertical bars that are centred at values such as –0.35, –0.25, –0.15, –0.05, and so forth. We will look first at the highest of the bars, which is centred at –0.15. This bar represents values of the temperature anomalies that fall in the interval from –0.2 to –0.1. The height of this bar is a representation of how many values fall into this interval, (23 observations, in this case). As it is the highest bar, this indicates that this is the interval in which the largest proportion of temperature anomalies fell for the period from 1921 to 1950. As you can see, there are virtually no temperature anomalies larger than 0.3. The height of these bars gives a useful overview of the distribution of the temperature anomalies.
Now consider how this distribution changes as we move through the three distinct time periods. The distribution is clearly moving to the right for the period 1981–2010, which is an indication that the temperature is increasing; in other words, an indication of global warming.
variance
A measure of dispersion in a frequency distribution, equal to the mean of the squares of the deviations from the arithmetic mean of the distribution. The variance is used to indicate how ‘spread out’ the data is. A higher variance means that the data is more spread out. Example: The set of numbers 1, 1, 1 has zero variance (no variation), while the set of numbers 1, 1, 999 has a high variance of 221,334 (large spread).
Now we will use our data to look at different aspects of distributions. Firstly, we will learn how to use deciles to determine which observations are ‘normal’ and ‘abnormal’, and then learn how to use variance to describe the shape of a distribution.
1. The New York Times article considers the bottom third (the lowest or coldest one-third) of temperature anomalies in 1951–1980 as ‘cold’ and the top third (the highest or hottest one-third) of anomalies as ‘hot’. In decile terms, temperatures in the 1st to 3rd decile are ‘cold’ and temperatures in the 7th to 10th decile or above are ‘hot’ (rounded to the nearest decile). Use R’s quantile function to determine what values correspond to the 3rd and 7th decile across all months in 1951–1980.
### R walk-through 1.5 Using the quantile function
First, we need to create a variable that contains all monthly anomalies in the years 1951–1980. Then, we use R’s quantile function to find the required percentiles (0.3 and 0.7 refer to the 3rd and 7th deciles, respectively).
Note: You may get slightly different values to those shown here if you are using the latest data.
# Select years 1951 to 1980
temp_all_months <- subset(tempdata,
(Year >= 1951 & Year <= 1980))
# Columns 2 to 13 contain months Jan to Dec.
temp_51to80 <- unlist(temp_all_months[, 2:13])
# c(0.3, 0.7) indicates the chosen percentiles.
perc <- quantile(temp_51to80, c(0.3, 0.7))
# The cold threshold
p30 <- perc[1]
p30
## 30%
## -0.1
# The hot threshold
p70 <- perc[2]
p70
## 70%
## 0.11
1. Based on the values you found in Question 3, count the number of anomalies that are considered ‘hot’ in 1981–2010, and express this as a percentage of all the temperature observations in that period. Does your answer suggest that we are experiencing hotter weather more frequently in 1981–2010? (Remember that each decile represents 10% of observations, so 30% of temperatures were considered ‘hot’ in 1951–1980.)
### R walk-through 1.6 Using the mean function
Note: You may get slightly different values to those shown here if you are using the latest data.
We repeat the steps used in R walk-through 1.5, now looking at monthly anomalies in the years 1981–2010. We can simply change the year values in the code from R walk-through 1.5.
# Select years 1981 to 2010
temp_all_months <- subset(tempdata,
(Year >= 1981 & Year <= 2010))
# Columns 2 to 13 contain months Jan to Dec.
temp_81to10 <- unlist(temp_all_months[, 2:13])
Now that we have all the monthly data for 1981–2010, we want to count the proportion of observations that are smaller than –0.1. This is easily achieved with the following lines of code:
paste("Proportion smaller than p30")
## [1] "Proportion smaller than p30"
temp <- temp_81to10 < p30
mean(temp)
## [1] 0.01944444
What we did was first create a variable called temp, which equals 1 (TRUE) for all the monthly temperature anomalies in temp_81to10 that are smaller than the 30th percentile value (temp_81to10 < p30), and 0 (FALSE) otherwise. The mean of this variable is the proportion of 1s. Here we find that 0.019 (= 1.9%) of observations are smaller than p30. That means that between 1951 and 1980, 30% of observations for the temperature anomaly were smaller than –0.10, but between 1981 and 2010 only about two per cent of months are considered cold. That is a large change.
Let’s check whether we get a similar result for the number of observations that are larger than 0.11.
paste("Proportion larger than p70")
## [1] "Proportion larger than p70"
mean(temp_81to10 > p70)
## [1] 0.8444444
1. The New York Times article discusses whether temperatures have become more variable over time. One way to measure temperature variability is by calculating the variance of the temperature distribution. For each season (DJF, MAM, JJA, and SON):
• Calculate the mean (average) and variance separately for the following time periods: 1921–1950, 1951–1980, and 1981–2010.
• For each season, compare the variances in different periods, and explain whether or not temperature appears to be more variable in later periods.
### R walk-through 1.7 Calculating and understanding mean and variance
One way to calculate mean and variance is to use the mosaic package introduced in R walk-through 1.4. (Remember to first install the mosaic package and load it into R with library(mosaic).)
# Only run if you haven't loaded mosaic yet
library(mosaic)
paste("Mean of DJF temperature anomalies across periods")
## [1] "Mean of DJF temperature anomalies across periods"
mean(~DJF|Period,data = tempdata)
## 1921-1950 1951-1980 1981-2010
## -0.0573333333 -0.0006666667 0.5206666667
paste("Variance of DJF anomalies across periods")
## [1] "Variance of DJF anomalies across periods"
var(~DJF|Period,data = tempdata)
## 1921-1950 1951-1980 1981-2010
## 0.05907540 0.05361333 0.07149609
Using the data in tempdata (data = tempdata), we calculated the mean (mean) and variance (var) of variable ~DJF separately for (|) each value of Period. The mosaic package allows us to calculate the means/variances for each period all at once. If mosaic is not loaded, you will get the error message: Error in mean(~DJF \| Period, data = tempdata) : unused argument (data = tempdata).
Looking at the results, it appears that it is not only the mean (December, January, and February) temperature anomaly that increases through 1981–2010, but also the variance.
Let’s calculate the variances through the periods for the other seasons.
paste("Variance of MAM anomalies across periods")
## [1] "Variance of MAM anomalies across periods"
var(~MAM|Period,data = tempdata)
## 1921-1950 1951-1980 1981-2010
## 0.03029069 0.02661333 0.07535126
paste("Variance of JJA anomalies across periods")
## [1] "Variance of JJA anomalies across periods"
var(~JJA|Period,data = tempdata)
## 1921-1950 1951-1980 1981-2010
## 0.01726713 0.01459264 0.06588690
paste("Variance of SON anomalies across periods")
## [1] "Variance of SON anomalies across periods"
var(~SON|Period,data = tempdata)
## 1921-1950 1951-1980 1981-2010
## 0.02421437 0.02587920 0.10431506
We recognize that the variances seem to remain fairly constant across the first two periods, but they do increase markedly for the 1981–2010 period.
We can plot a line chart to see these changes graphically. (This type of chart is formally known as a ‘time-series plot’). Make sure to change the chart title according to the latest year in your data (here we used 2016).
plot(tempdata$DJF, type = "l", col = "blue", lwd = 2, ylab = "Annual temperature anomalies", xlab = "Year") # \n creates a line break title("Average temperature anomaly in DJF and JJA \n in the northern hemisphere (1880-2016)") # Add a horizontal line (at y = 0) abline(h = 0, col = "darkorange2", lwd = 2) lines(tempdata$JJA, col = "darkgreen", lwd = 2)
# Add a label to the horizontal line
text(1895, 0.1, "1951-1980 average")
legend(1880, 1.5, legend = c("DJF", "JJA"),
col = c("blue", "darkgreen"),
lty = 1, cex = 0.8, lwd = 2)
Figure 1.7 Northern hemisphere winter and summer quarter temperatures (1958–2016).
1. Using the findings of the New York Times article and your answers to Questions 1 to 5, discuss whether temperature appears to be more variable over time. Would you advise the government to spend more money on mitigating the effects of extreme weather events?
## Part 1.3 Carbon emissions and the environment
### Learning objectives for this part
• use scatterplots and the correlation coefficient to assess the degree of association between two variables
• explain what correlation measures and the limitations of correlation.
correlation
A measure of how closely related two variables are. Two variables are correlated if knowing the value of one variable provides information on the likely value of the other, for example high values of one variable being commonly observed along with high values of the other variable. Correlation can be positive or negative. It is negative when high values of one variable are observed with low values of the other. Correlation does not mean that there is a causal relationship between the variables. Example: When the weather is hotter, purchases of ice cream are higher. Temperature and ice cream sales are positively correlated. On the other hand, if purchases of hot beverages decrease when the weather is hotter, we say that temperature and hot beverage sales are negatively correlated.
correlation coefficient
A numerical measure, ranging between 1 and −1, of how closely associated two variables are—whether they tend to rise and fall together, or move in opposite directions. A positive coefficient indicates that when one variable takes a high (low) value, the other tends to be high (low) too, and a negative coefficient indicates that when one variable is high the other is likely to be low. A value of 1 or −1 indicates that knowing the value of one of the variables would allow you to perfectly predict the value of the other. A value of 0 indicates that knowing one of the variables provides no information about the value of the other.
The government has heard that carbon emissions could be responsible for climate change, and has asked you to investigate whether this is the case. To do so, we are now going to look at carbon emissions over time, and use another type of chart, the scatterplot, to show their relationship to temperature anomalies. One way to measure the relationship between two variables is correlation. R walk-through 1.8 explains what correlation is and how to calculate it in R.
In the questions below, we will make charts using the CO2 data from the US National Oceanic and Atmospheric Administration. Download the Excel spreadsheet containing this data. Save the data as a csv file and import it into R.
1. The CO2 data was recorded from one observatory in Mauna Loa. Using an Earth System Research Laboratory article as a reference, explain whether or not you think this data is a reliable representation of the global atmosphere.
1. The variables trend and interpolated are similar, but not identical. In your own words, explain the difference between these two measures of CO2 levels. Why might there be seasonal variation in CO2 levels?
Now we will use a line chart to look for general patterns over time.
1. Plot a line chart with interpolated and trend CO2 levels on the vertical axis and time (starting from January 1960) on the horizontal axis. Label the axes and the chart legend, and give your chart an appropriate title. What does this chart suggest about the relationship between CO2 and time?
We will now combine the CO2 data with the temperature data from Part 1.1, and then examine the relationship between these two variables visually using scatterplots, and statistically using the correlation coefficient. If you have not yet downloaded the temperature data, follow the instructions in Part 1.1.
1. Choose one month and add the CO2 trend data to the temperature dataset from Part 1.1, making sure that the data corresponds to the correct year.
• Make a scatterplot of CO2 level on the vertical axis and temperature anomaly on the horizontal axis.
• Calculate and interpret the (Pearson) correlation coefficient between these two variables.
• Discuss the shortcomings of using this coefficient to summarize the relationship between variables.
### R walk-through 1.8 Scatterplots and the correlation coefficient
First we will use the read.csv function to import the CO2 datafile into R, and call it CO2data.
CO2data <- read.csv("1_CO2 data.csv")
This file has monthly data, but in contrast to the data in tempdata, the data is all in one column (this is more conventional than the column per month format). To make this task easier, we will pick the June data from the CO2 emissions and add them as an additional variable to the tempdata dataset.
R has a convenient function called merge to do this. First we create a new dataset that contains only the June emissions data (‘CO2data_june’).
CO2data_june <- CO2data[CO2data$Month == 6,] Then we use this data in the merge function. The merge function takes the original ‘tempdata’ and the ‘CO2data’ and merges (combines) them together. As the two dataframes have a common variable, Year, R automatically matches the data by year. (Extension: Look up ?merge or Google ‘How to use the R merge function’ to figure out what all.x does, and to see other options that this function allows.) names(CO2data)[1] <- "Year" tempCO2data <- merge(tempdata, CO2data_june) Let us have a look at the data and check that it was combined correctly: head(tempCO2data[, c("Year", "Jun", "Trend")]) ## Year Jun Trend ## 1 1958 0.04 314.85 ## 2 1959 0.14 315.92 ## 3 1960 0.18 317.36 ## 4 1961 0.19 317.48 ## 5 1962 -0.10 318.27 ## 6 1963 -0.02 319.16 To make a scatterplot, we use the plot function. R’s default chart for plot is a scatterplot, so we do not need to specify the chart type. One new option that applies to scatterplots is pch = , which determines the appearance of the data points. The number 16 corresponds to filled-in circles, but you can experiment with other numbers (from 0 to 25) to see what the data points look like. plot(tempCO2data$Jun, tempCO2data$Trend, xlab = "Temperature anomaly (degrees Celsius)", ylab = "CO2 levels (trend, mole fraction)", pch = 16, col = "blue") title("Scatterplot for CO2 emissions and temperature anomalies") Figure 1.8 CO2 emissions and northern hemisphere June temperatures (1958–2016). The cor function calculates the correlation coefficient. Note: You may get slightly different results if you are using the latest data. cor(tempCO2data$Jun, tempCO2dataTrend) ## [1] 0.9157744 In this case, the correlation coefficient tells us that the data is quite close to resembling an upward-sloping straight line (as seen on the scatterplot). There is a strong positive association between the two variables (higher temperature anomalies are associated with higher CO2 levels). One limitation of this correlation measure is that it only tells us about the strength of the upward- or downward-sloping linear relationship between two variables, in other words how closely the scatterplot aligns along an upward- or downward-sloping straight line. The correlation coefficient cannot tell us if the two variables have a different kind of relationship (such as that represented by a wavy line). Note: The word ‘strong’ is used for coefficients that are close to 1 or −1, and ‘weak’ is used for coefficients that are close to 0, though there is no precise range of values that are considered ‘strong’ or ‘weak’. If you need more insight into correlation coefficients, you may find it helpful to watch online tutorials such as ‘Correlation coefficient intuition’ from the Khan Academy. As we are dealing with time-series data, it is often more instructive to look at a line plot, as a scatterplot cannot convey how the observations relate to each other in the time dimension. If you were to check the variable types (using str(tempCO2data)), you would see that the data is not yet in time-series format. We could continue with the format as it is, but for plotting purposes it is useful to let R know that we are dealing with time-series data. We therefore apply the ts function as we did in Part 1.1. tempCO2dataJun <- ts(tempCO2data$Jun, start = c(1958), end = c(2017), frequency = 1) tempCO2data$Trend <- ts(tempCO2data$Trend, start = c(1958), end = c(2017), frequency = 1) Let’s start by plotting the June temperature anomalies. plot(tempCO2data$Jun, type = "l", col = "blue", lwd = 2,
ylab = "June temperature anomalies", xlab = "Year")
title("June temperature anomalies and CO2 emissions")
Figure 1.9 Northern hemisphere June temperatures (1958–2016).
Typically, when using the plot function we would now only need to add the line for the second variable using the lines command. The issue, however, is that the CO2 emissions variable (Trend) is on a different scale, and the automatic vertical axis scale (from –0.2 to about 1.2) would not allow for the display of Trend. To resolve this issue you can introduce a second vertical axis using the commands below. (Tip: You are unlikely to remember the exact commands required, however you can Google ‘R plot 2 vertical axes’ or a similar search term, and then adjust the code you find so it will work on your dataset.)
# Create extra margins used for the second axis
par(mar = c(5, 5, 2, 5))
plot(tempCO2data$Jun, type = "l", col = "blue", lwd = 2, ylab = "June temperature anomalies", xlab = "Year") title("June temperature anomalies and CO2 emissions") # This puts the next plot into the same picture. par(new = T) # No axis, no labels plot(tempCO2data$Trend, pch = 16, lwd = 2,
axes = FALSE, xlab = NA, ylab = NA, cex = 1.2)
axis(side = 4)
mtext(side = 4, line = 3, 'CO2 emissions')
legend("topleft", legend = c("June temp anom", "CO2 emis"),
lty = c(1, 1), col = c("blue", "black"), lwd = 2)
causation
A direction from cause to effect, establishing that a change in one variable produces a change in another. While a correlation gives an indication of whether two variables move together (either in the same or opposite directions), causation means that there is a mechanism that explains this association. Example: We know that higher levels of CO2 in the atmosphere lead to a greenhouse effect, which warms the Earth’s surface. Therefore we can say that higher CO2 levels are the cause of higher surface temperatures.
spurious correlation
A strong linear association between two variables that does not result from any direct relationship, but instead may be due to coincidence or to another unseen factor.
Figure 1.10 CO2 emissions and northern hemisphere June temperatures (1958–2016).
This line graph not only shows how the two variables move together in general, but also clearly demonstrates that both variables display a clear upward trend over the sample period. This is an important feature of many (not all) time series variables, and is important for the interpretation (see the ‘Find out more’ box on spurious correlations that follows).
1. Extra practice: Choose two months and add the CO2 trend data to the temperature dataset from Part 1.1, making sure that the data corresponds to the correct year. Create a separate chart for each month. What do your charts and the correlation coefficients suggest about the relationship between CO2 levels and temperature anomalies?
Even though two variables are strongly correlated with each other, this is not necessarily because one variable’s behaviour is the result of the other (a characteristic known as causation). The two variables could be spuriously correlated. The following example illustrates spurious correlation:
A child’s academic performance may be positively correlated with the size of the child’s house or the number of rooms in the house, but could we conclude that building an extra room would make a child smarter, or doing well at school would make someone’s house bigger? It is more plausible that income or wealth, which determines the size of home that a family can afford and the resources available for studying, is the ‘unseen factor’ in this relationship. We could also determine whether income is the reason for this spurious correlation by comparing exam scores for children whose parents have similar incomes but different house sizes. If there is no correlation between exam scores and house size, then we can deduce that house size was not ‘causing’ exam scores (or vice versa).
See this TEDx Talk for more examples of the dangers of confusing correlation with causation.
1. Consider the example of spurious correlation described above.
• In your own words, explain spurious correlation and the difference between correlation and causation.
• Give an example of spurious correlation, similar to the one above, for either CO2 levels or temperature anomalies.
• Choose an example of spurious correlation from Tyler Vigen’s website. Explain whether you think it is a coincidence, or whether this correlation could be due to one or more other variables.
### Find out more What makes some correlations spurious?
In the spurious correlations website given in Question 6(c), most of the examples you will see involve data series (variables) that are trending (meaning that they tend to increase or decrease over time). If you calculate a correlation between two variables that are trending, you are bound to find a large positive or negative correlation coefficient, even if there is no plausible explanation for a relationship between the two variables. For example, ‘per capita cheese consumption’ (which increases over time due to increased disposable incomes or greater availability of cheese) has a correlation coefficient of 0.95 with the ‘number of people who die from becoming tangled in their bedsheets’ (which also increases over time due to a growing population and a growing availability of bedsheets).
The case for our example (the relationship between temperature and CO2 emissions) is slightly different. There is a well-known chemical link between the two. So we understand how CO2 emissions could potentially cause changes in temperature. But in general, do not be tempted to conclude that there is a causal link just because a high correlation coefficient can be seen. Be very cautious when attaching too much meaning to high correlation coefficients when the data displays trending behaviour.
This part shows that summary statistics, such as the correlation coefficient, can help identify possible patterns or relationships between variables, but we cannot draw conclusions about causation from them alone. It is also important to think about other explanations for what we see in the data, and whether we would expect there to be a relationship between the two variables.
natural experiment
An empirical study exploiting naturally occurring statistical controls in which researchers do not have the ability to assign participants to treatment and control groups, as is the case in conventional experiments. Instead, differences in law, policy, weather, or other events can offer the opportunity to analyse populations as if they had been part of an experiment. The validity of such studies depends on the premise that the assignment of subjects to the naturally occurring treatment and control groups can be plausibly argued to be random.
However, there are ways to determine whether there is a causal relationship between two variables, for example, by looking at the scientific processes that connect the variables (as with CO2 and temperature anomalies), or by using a natural experiment. To read more about how natural experiments help evaluate whether one variable causes another, see Section 1.8 of Economy, Society, and Public Policy. In Empirical Project 3, we will take a closer look at natural experiments and how we can use them to identify causal links between variables.
|
{"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": 0.4561224579811096, "perplexity": 1146.894725761285}, "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-2021-39/segments/1631780058263.20/warc/CC-MAIN-20210927030035-20210927060035-00162.warc.gz"}
|
http://mathhelpforum.com/algebra/190230-simultaneous-equations.html
|
# Math Help - Simultaneous Equations.
1. ## Simultaneous Equations.
I was wondering if you could doublecheck this question please:
g) $y=2x$ and $y = 2x^2$
y = 4 and x = 2
How would I do this?
h) $y= 6 - x^2$ and $y = 4x +1$
2. ## Re: Simultaneous Equations.
Originally Posted by JibblyJabbly
I was wondering if you could doublecheck this question please:
g) $y=2x$ and $y = 2x^2$
y = 4 and x = 2
no
How would I do this?
h) $y= 6 - x^2$ and $y = 4x +1$
g)
$2x = 2x^2$
$2x - 2x^2 = 0$
$2x(1 - x) = 0$
$x = 0$ and $x = 1$
h)
$6-x^2 = 4x+1$
$0 = x^2 + 4x - 5$
factor and use the zero product property to solve for x
3. ## Re: Simultaneous Equations.
In case a graph helps...
g) $y=2x,y=2x^2$. The red line is $y=2x^2$ and the blue line is $y=2x$.
Clearly solutions are $x=0,1$
h) $y=6-x^2,y=4x+1$. The red line is $y=4x+1$ and the blue line is $y=6-x^2$.
Clearly solutions are $x=1,-5$
The value of y can be calculated just by substituting the value of x or by the graph.
4. ## Re: Simultaneous Equations.
Yet another way to do (g): $y=2x$ and $y=2x^2$:
If x and y are not 0, $\frac{y}{y}= /frac{2x^2}{2x}$, [tex]1= x[/itex]. And if x= 1, what is y?
That was "if x and y are not 0". It is easy to check that y is 0 if and only if x is and x= y= 0 satifies both equations.
|
{"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": 0, "img_math": 0, "codecogs_latex": 26, "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": 0.7070300579071045, "perplexity": 899.2115894691067}, "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-2014-41/segments/1410657138770.35/warc/CC-MAIN-20140914011218-00170-ip-10-234-18-248.ec2.internal.warc.gz"}
|
https://ingmarschuster.com/2016/01/21/why-the-map-is-a-bad-starting-point-in-high-dimensions/
|
# Why the MAP is a bad starting point in high dimensions
During MCMSki 2016, Heiko mentioned that in high dimensions, the MAP is not a particularly good starting point for a Monte Carlo sampler, because there is no volume around it. I and several people smarter than me where not sure why that could be the case, so Heiko gave us a proof by simulation: he sampled from multivariate standard normals with increasing dimensions and plotted the euclidean norm of the samples. The following is what I reproduced for sampling a standard normal in $D=30$ dimensions.The histogram has a peak at about $\sqrt{D}$, which means most of the samples are in a sphere around the mean/mode/MAP of the target distribution and none are at the MAP, which would correspond to norm $0$.
We where dumbstruck by this, but nobody (not even Heiko) had an explanation for what was happening. Yesterday I asked Nicolas about this and he gave the most intuitive interpretation: Given a standard normal variable in $D$ dimensions, $x \sim \mathcal{N}(0,I_D)$, computing the euclidean norm you get $n^2 = \|x\|^2 = \sum_{i=1}^D x_i^2$. But as $x$ is gaussian, this just means $n^2$ has a $\chi^2(D)$ distribution, which results in the expected value $\mathbb{E}(n) = \sqrt{D}$. Voici l’explication.
(Title image (c) Niki Odolphie)
## 8 thoughts on “Why the MAP is a bad starting point in high dimensions”
1. Joseph says:
Check out the introductory chapter of Giraud, Introduction to High-Dimensional Statistics, CRC, 2015!
Like
2. Marco says:
Nice! The norm of normally distributed vectors is indeed a chi distribution
https://en.wikipedia.org/wiki/Chi_distribution
which has interestingly a variance of $D-\mu^2$, hence quasi-constant in our case where the mean is very close to $\sqrt{D}$. That’s why as we increase the dimension and the mean goes farther away from zero the area with non-zero mass appears to be shrinking!
Like
3. Nice post!
A note on the Chi2: http://goo.gl/Sghwc4
Just wanted to add one thing, to clarify what I meant.
Using the MAP to initialise an MCMC run is not the best idea ever, but it also it not really a bad idea. Any (converging) sampler will eventually move to the typical set. So the worst thing that can happen is to loose a bit of computing power when in moving from the MAP to the typical set. If your sampler is geometrically ergodic for example, it will do so at a geometric rate — from *any* starting point. You can easily see that if you use a RWMH on a high dimensional Gaussian and start it at the mode — the traces will (slowly in high dimensions) move to the sphere you were talking about in the blog post.
What *is* a bad idea in high dimensions, however, is to use the MAP to represent your probability distribution. That is, MAP point estimates, when used to summarise a model give a quite different answer to using a single sample from the posterior. If you do a Gaussian linear regression in high dimensions, and compare the predictive posterior using MAP and MCMC, you will see.
Like
4. Isn’t this observation simply that neighbourhoods are smaller in high dimensions than we might intuitively suppose? For a Normal in high dimensions the mean/mode/map remains the point at which samples are typically nearest; there isn’t a starting point closer to the mass, right?
e.g. D=30; N=1000; X <- matrix(rnorm(D*N),nrow=D,ncol=N); hist(sqrt(colSums((X)^2)),col="black"); for (i in 1:10) {R = 2*i/D; hist(sqrt(colSums((X-R)^2)),add=T,border=hsv(i/10*0.6),plot.new=F)}
Like
1. Yes, the mean is the one point that has the shortest distance to the $\sqrt{D}$ sphere in which the posterior mass concentrates.
However, for several Markovian proposal kernels $q(\cdot|x)$, a good starting point would be in that $\sqrt{D}$ sphere, not at the mean. An intuition could be that you actually start from equilibrium in that case, i.e. $x \sim \pi$, instead of having to converge first.
Obviously, there are exceptions, the easiest being when using an independent proposal $q(\cdot)$ where the current point doesn’t matter.
Like
1. Interesting perspective; I disagree of course: I don’t think one is any closer to equilibrium for a RW MCMC by starting in the sphere than at the MAP, it just looks that way when you collapse the parameter space (arbitrarily) down to a single radial axis.
Like
5. Joseph says:
Well, this so-called sphere has actually a massive volume, that’s why it aggregates so much probability mass even though the density decreases. In high dimension there is no point, including the MAP, that summarizes the whole distribution well. But there is also no point better than the MAP. Do the same plot again with another point as the origin …
Like
1. Then the expected distance from that other point will be higher of course. Which reiterates Ewans point, but makes it more intuitive (to me).
Like
|
{"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": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 17, "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": 0.8902480602264404, "perplexity": 665.5670437612652}, "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-2018-22/segments/1526794863410.22/warc/CC-MAIN-20180520112233-20180520132233-00081.warc.gz"}
|
http://clay6.com/qa/26296/if-phi-n-f-n-g-n-where-f-n-g-n-c-and-large-frac-frac-frac-frac-then-value-o
|
# If $\phi (n) =f(n) g(n),$ where $f'(n) g'(n) =C$ and $\large\frac {\phi ''}{\phi} =\frac {f''}{f} +\frac{g''}{g}+\frac{Kc}{fg}$ then value of K.
$(a)\;1 \\ (b)\;0 \\ (c)\;2 \\ (d)\;-1$
$\phi(x)=f(x)g(x)$
$\phi'(x) =f'(x)g(x) +f(x) g'(x)$
$\phi''(x) =f'(x)g(x) +f''(x) g'(x)+f''(x) g'(x) +f(x)g'(x)$
$\phi''(x) =2c+f''(x) g(x)+f(n) g''(x)$
$\large\frac{\phi ''(x)}{\phi (n)}=\frac{2c}{f(n) g(n) } +\frac{f''(x)}{f(x)}+\frac{g''(x)}{g(x)}$
$K=2$
Hence c is the correct answer.
|
{"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": 1, "mathjax_asciimath": 0, "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": 0.9990105032920837, "perplexity": 194.90246562563232}, "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-2017-51/segments/1512948514113.3/warc/CC-MAIN-20171211222541-20171212002541-00689.warc.gz"}
|
https://computergraphics.stackexchange.com/questions/4715/where-do-the-coefficients-in-the-catmull-clark-subdivision-algorithm-come-from
|
# Where do the coefficients in the Catmull-Clark subdivision algorithm come from?
I'm learning about subdivision surface algorithms. The "Catmull-Clark" algorithm seems to be one of the most widely-used classical algorithms.
The introduction of new face points and edges is straightforward, but I'm confused by the following formula for modifying the locations of original points
$$\frac{F + 2R + (n-3)P}{n}$$
where:
• $P$ is the original point
• $R$ is the average of all $n$ edges midpoints touching $P$
• $F$ is the average of all $n$ face points touching $P$
I understand the result is a weighted average of three points $F$, $R$ and $P$, but where do the coefficients $1$, $2$, and $(n-3)$ come from? Why $2R$? Why not $2.01R$? Or $1R$ and $2F$?
All the introductions I've seen just present the formula without presenting a justification.
The derivation is presented in the original paper that introduced CC subdivisions as a generalisation of B-Spline patches: https://people.eecs.berkeley.edu/~sequin/CS284/PAPERS/CatmullClark_SDSurf.pdf
• Thanks. I'm struggling to follow the derivation somewhat. If I'm not wrong, every entry of the $H_1$ matrix should be multiplied by a factor of $\frac{1}{8}$. – eigenchris Feb 15 '17 at 5:08
• Thanks for the link, but in general link-only answers are discouraged on StackExchange. I'm not suggesting you paste the entire derivation in, but perhaps you could summarize the key points (e.g. assumptions that lead to the specific coefficients) in your answer? – Nathan Reed Feb 20 '17 at 16:00
I'm just going to add a few more details to the paper that Stefan linked to.
First of all, the matrix $H_1$ displayed in the paper is incorrect; every element should be multiplied by a factor of $\frac{1}{8}$.
$$H_1 = \frac{1}{8} \begin{bmatrix} 4 & 4 & 0 & 0 \\ 1 & 6 & 1 & 0 \\ 0 & 4 & 4 & 0 \\ 0 & 1 & 6 & 1 \end{bmatrix}$$
Second, the derivation of the new face point formula for quads in the first half of the paper is confusing, so I will fill in some of the details.
The matrix $G_1 = HGH^T$ contains the 16 control points for one sub-quad of the original quad with control points $G$. The entries of $G_1$ are referred to with $q_{i,j}$. Of most interest are the elements $q_{1,1}$, $q_{1,2}$ and $q_{2,2}$, which represent control points for a corner, edge, and interior of the $4\times 4$ control point grid for the sub-quad. All the other elements have similar formulas due to the symmetry of the subdivision process.
By carrying out the matrix multiplication, we get:
$q_{2,2} = \frac{P_{1,1} +P_{3,1} +P_{3,1} +P_{3,3}}{64} + \frac{6(P_{1,2} +P_{2,1} +P_{3,2} +P_{2,3})}{64} + \frac{36P_{2,2}}{64}$
We can see from this formula that, when relocating a control point, its new location is determined by the $3\times 3$ grid of points surrounding it. Here we see that in this grid, corner points have $\frac{1}{64}$ influence, edge points have $\frac{6}{64} = \frac{3}{32}$ influence, and the center ("old") point has $\frac{36}{64} = \frac{9}{16}$ influence. These weights are consistent with the ones given at the bottom of this blog post.
With a bit of rearranging, we get:
$q_{2,2} = \frac{1}{4} \big[ \frac{1}{4}(\frac{P_{1,1} + P_{1,2} + P_{2,1} + P_{2,2}}{4} + \frac{P_{1,2} + P_{2,2} + P_{1,3} + P_{2,3}}{4} + \frac{P_{2,1} + P_{2,2} + P_{3,2} + P_{3,1}}{4} + \frac{P_{2,2} + P_{2,3} + P_{3,2} + P_{3,3}}{4}) + 2\frac{1}{4}(\frac{P_{1,2} + P_{2,2}}{2} + \frac{P_{2,1} + P_{2,2}}{2} + \frac{P_{2,3} + P_{2,2}}{2} + \frac{P_{3,2} + P_{2,2}}{2}) + P_{2,2}\big]$
The first term is merely the average of the four surrounding face points; in other words, it is $F$. The second term is the average of the four surrounding edge midpoints multiplied by $2$; in other words, it is $2R$. Finally, $P_{2,2}$ is simply the original control point $P$.
And so we see this is the same as the original formula for quads: $\frac{1}{4}(F + 2R + P)$.
The paper does not provide a derivation of the general case for an $n$-sided polygon, but it seems like a reasonable extension based on intuition.
As an aside, here is an explanation for the other points, and their meanings as seen on wikipedia:
$q_{1,1} = \frac{P_{1,1} +P_{1,2} +P_{2,1} +P_{2,2}}{4}$
This is simply the formula for adding a new control point at the center of an existing quad.
$q_{1,2} = \frac{P_{1,1} +P_{1,2} +P_{2,1} +P_{2,3}}{16} + \frac{6(P_{1,2} +P_{2,1})}{16}$
Rearranging this, we see it is just the average of the two neighbouring face points and the edge endpoints:
$q_{1,2} = \frac{1}{4}(\frac{P_{1,1} +P_{2,1} +P_{1,2} +P_{2,2}}{4} + \frac{P_{1,2} +P_{2,2} +P_{1,3} +P_{2,3}}{4} + P_{1,2} + P_{2,1})$
|
{"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": 1, "mathjax_asciimath": 0, "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": 0.8420752286911011, "perplexity": 260.33339790730196}, "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-2019-22/segments/1558232256980.46/warc/CC-MAIN-20190522223411-20190523005411-00042.warc.gz"}
|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3353155/?tool=pubmed
|
• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Parasit Vectors. 2012; 5: 66.
Published online Mar 31, 2012.
PMCID: PMC3353155
# Evaluation of the long-term efficacy and safety of an imidacloprid 10%/flumethrin 4.5% polymer matrix collar (Seresto®) in dogs and cats naturally infested with fleas and/or ticks in multicentre clinical field studies in Europe
## Abstract
### Background
The objective of these two GCP multicentre European clinical field studies was to evaluate the long-term efficacy and safety of a new imidacloprid/flumethrin collar (Seresto®, Bayer AnimalHealth, Investigational Veterinary Product(IVP)) in dogs and cats naturally infested with fleas and/or ticks in comparison to a dimpylat collar ("Ungezieferband fuer Hunde/fuer Katzen", Beaphar, Control Product (CP)).
### Methods
232 (IVP) and 81 (CP) cats and 271(IVP) and 129 (CP) dogs were treated with either product according to label claims and formed the safety population. Flea and tick counts were conducted in monthly intervals for up to 8 months in the efficacy subpopulation consisting of 118 (IVP) + 47 (CP) cats and 197 (IVP) + 94 (CP) dogs. Efficacy was calculated as reduction of infestation rate within the same treatment group and statistically compared between the two treatment groups.
### Results
Preventive efficacy against fleas in cats/dogs varied in the IVP group between 97.4%/94.1% and 100%/100% (overall mean: 98.3%/96.7%) throughout the 8 month period and in the CP group between 57.1%/28.2% and 96.1%/67.8% (overall mean: 79.3%/57.9%). Preventive efficacy against ticks in cats/dogs varied in the IVP group between 94.0%/91.2% and 100%/100% (overall mean: 98.4%/94.7%) throughout the 8 month period and in the CP group between 90.7%/79.9% and 100%/88.0% (overall mean: 96.9%/85.6%). The IVP group was statistically non-inferior to the CP group, and on various assessment days, statistical superiority was proven for flea and tick count reduction in dogs and cats. Both treatments proved to be safe in dogs and cats with mainly minor local observations at the application site. There was moreover, no incidence of any mechanical problem with the collar in dogs and cats during the entire study period.
### Conclusions
The imidacloprid/flumethrin collar proved to reduce tick counts by at least 90% and flea counts by at least 95% for a period of at least 7-8 months in cats and dogs under field conditions. Therefore, it can be used as sustainable long-term preventative, covering the whole flea and tick season.
Keywords: Ctenocephalides felis, Ctenocephalides canis, Archaeopsylla erinacei, Pulex irritans, Dermacentor reticulatus, Ixodes hexagonus, Ixodes ricinus, Fleas, Ticks, Efficacy, Safety, Imidacloprid, Flumethrin, Collar, Field
## Background
Fleas and ticks are common ectoparasites in dogs and cats and are present in many areas of the world, in differing intensity depending on the climatic conditions. Fleas are present in all areas of Europe, with Ctenocephalides felis being the most frequent flea species on our companion animals followed by Ctenocephalides canis. The main European tick species are Rhipicephalus sanguineus (dog); Ixodes ricinus (cat and dog), Dermacentor reticulatus (dog) and Rhipicephalus turanicus (cat). The latter species is not very well recognized but recently acknowledged to be the species present on cats instead of the nearly identical but very dog specific R. sanguineus [1]. Fleas tend to occur from spring to winter and are capable of acting as vectors for several diseases, e.g. bartonellosis and tapeworms, and can cause flea allergic dermatitis (FAD). Ticks peak from early spring to late autumn and are important vectors for several diseases, e.g. borreliosis, anaplasmosis, ehrlichiosis and babesiosis. In humans they can transmit tick encephalitis, borreliosis and anaplasmosis. Both fleas and ticks play an important role as vectors [2]. Therefore, effective measures against these parasites are important in preventing feline, canine and human disease [3].
While there are many authorized products containing different active ingredients for the prevention of fleas, there are only a few products available against ticks. Products containing fipronil are almost the only option for tick treatment of cats and dogs as the other common acaricides, permethrin and amitraz, are indicated for dogs only [4,5] and are contraindicated for use in cats due to serious safety concerns. Flumethrin, the acaricidal active component in Kiltix® collars (propoxur 10%/flumethrin 2.25%), is a highly potent acaricide known to be safe in various animal species including cattle, sheep and dogs but also cats: the Kiltix® collar was, up to-date the only broadly marketed pyrethroid containing formulation suitable for cats.
Formulations of these active ingredients are generally designed for topical application with the most common versions being collars and low volume fluids (spot ons): Collars have been used frequently for the treatment and prevention of flea and tick infestations in dogs and cats in the past decades in Europe and abroad [6,7]. However, with the launch of spot-on topical formulations and concerns about the perceived potential risk for free roaming cats to be trapped by any salient piece of wood or other rigid material, collars have been less involved in the growing market for flea and tick control.
Seresto® (Bayer Animal Health), a new collar for dogs and cats, provides long term broad spectrum parasiticidal activity by combining the insecticidal properties of imidacloprid with the acaricidal properties of flumethrin. The collar matrix system ensures that both active ingredients are slowly and continuously released from the collar towards the animal thereby avoiding peak concentrations and ensuring that acaricidal/insecticidal concentrations of both active ingredients are present in the cat's or dog's hair coat during the entire efficacy period. The active ingredients spread from the site of direct contact over the entire skin surface of the treated animal [8].
Following application of the collar, both active ingredients remain on the outer surface of the animal's skin and hair coat, enabling them to come into contact with the target parasites and display their efficacy. The neonicotinoid imidacloprid interacts with the nicotinic acetylcholine receptors (nAChRs) on the post-synaptic membrane [9], while flumethrin, as an α-cyano-(type II)-pyrethroid, exhibits excitatory efficacy by blocking the voltage gated axonic sodium channels [9]. As recently described in laboratory studies [9], imidacloprid and flumethrin have synergistic efficacy on insects, in particular fleas. Both active ingredients are well known on the ectoparasiticide market: imidacloprid has been the insecticidal active ingredient in products such as Advantage®, Advantix® and Advocate® since 1996 while flumethrin has been registered since 1986 for animal use and has already been used extensively in livestock animals (esp. cattle). It has also been used for more than a decade in the EU as an active ingredient in companion animal products (dogs and in parts of the EU also cats): Kiltix® collar [6].
As usual for clinical field studies, a full set of laboratory efficacy and safety studies was a prerequisite for conducting the herein described studies. According to a set of preceding laboratory in-vivo studies the collar provides long term (8 month) prevention for cats and dogs against ticks (cats: I. ricinus, R. turanicus (= the Rhipicephalus species on cats, [1]) dogs: I. ricinus, I. scapularis, R. sanguineus, D. reticulatus) and fleas (C. felis,) [10,11]. The collar proved also to be effective against the tick species Amblyomma americanum (USA) and Dermacentor variabilis (USA) [10,11]. The collar's safety has been shown in longterm, overdosage studies following the guideline on target animal safety (VICH GL43) as well as US EPA requirements at up to 5 times the target dose in both cats and dogs, 10 week old kittens and 7 week old puppies [12]. Additionally, to this standard study set, a specific product safety concern for cats was addressed before study start: their particular sensitivity towards pyrethroids [13]. This sensitivity is generally explained by a reduced enzyme pattern for hydrolysis of pyrethroid-esters in cats, and by toxic metabolites developing during the pyrethroid degradation process combined with the reduced glucuronidation and therefore excretion capacity of the feline liver [14-16]. Opposite to e.g. permethrin and deltamethrin, the metabolism of flumethrin is simple without the need for glucuronidation. Flumethrin itself or its main metabolite flumethrin acid can be excreted without conjugation via feces [17]. Moreover, flumethrin acid is pharmacologically inactive [18]. The decreased feline glucuronidation rate is therefore toxicologically irrelevant [17]. Accordingly the NOAEL (No Observed Adverse Effect Level) for flumethrin is identical for dogs and cats [19]. The already rather low flumethrin toxicity in cats is complemented in this new product by two other aspects: only a very low hair coat concentration of this highly effective acaricide is necessary for high efficacy against ticks, and this low amount is released steadily from the collar without peak concentrations [9]. These three aspects together form the basis for the collar to be a useful application form for an effective and safe cat acaricide.
This results in a special benefit of the imidacloprid 10%/flumethrin 4.5% collar when tick and flea treatment is necessary in mixed cat and dog households. As the cat and dog products are identical, dogs living closely together with cats can be protected against ectoparasites without safety concerns about cats potentially ingesting critical amounts of active ingredient through mutual grooming.
Besides the classical target animal safety evaluation, the particular pharmaceutical application via a collar bears another safety relevant aspect for cats which was taken into account and tested before the collar was used in the discussed field study: in contrast to dogs, which usually wear constantly leather or chain collars, cats are less often equipped with these accessories by their owners. The reason for this is the different behaviour of this species; free roaming cats displaying the full range of their hunting instinct are known to roam through wood, scrub or other wayless terrain and to pass through particularly narrow apertures when hunting their prey. Cat owners often fear that cats may be captured or strangulated by a collar, which may get caught on any salient piece of wood or other rigid material, and so cats are perceived to be more at risk wearing a collar. The new collar has an integral safety-closure ratchet mechanism that is constructed to yield at approximately 50 Newton (~5 kg) traction [Jiritschka W, Imidacloprid/Flumethrin - collar: Determination of force needed to re-open the collar using the integral closing system, unpublished], and allows the collar to be widened by the distance to the next rib. Widening by two or three rib spaces will usually easily allow a cat to escape from the collar in the unlikely case that it gets trapped. 50 Newton is the force a 2 kg cat needs to jump to a height of just 40 cm. This is easily brought to bear by even a small cat, which seriously wants to escape from somewhere but is strong enough to keep the collar on the cat's neck under normal circumstances and to prevent the cat from accidentally losing it. Additionally the collar design prevents the collar from widening to the extent that can occur in certain elastic collars, where cats may be endangered by getting the front leg stuck in the over-widened collar; in this case severe skin damage may occur as the leg becomes hooked at the elbow and cannot be retracted by the animal itself.
A second, backup security feature for cats is represented by the "pre-determined breaking point" of the cat collar. In contrast to the approximate 140 Newton (~14 kg) traction necessary to break the cat collar itself, this pre-determined area breaks at approximately 80 Newton (~8 kg) [Jiritschka W, Imidacloprid/Flumethrin - collar: Determination of force needed to disrupt the collar, unpublished]. So even in cases where the safety-closure mechanism is blocked by any unfortunate accident, the animal has an increased chance to escape by breaking the collar.
The extended safety profile described above and initial efficacy data of the new collar in both cats and dogs was a prerequisite to apply for permission to use it in pets naturally infested with fleas and ticks under field conditions. The objective of the present therapeutic confirmatory, controlled, randomised, blocked, multi-centre and multi-regional field study was accordingly to confirm the long-term efficacy and safety of the combination of "imidacloprid 10%/flumethrin 4.5%" administered by collar for the treatment of natural infestations of fleas and/or ticks in cats and dogs, presenting as patients in European veterinary practices and based on statistical non-inferiority as compared with a licensed collar product for cats and dogs. Statistical non-inferiority of the imidacloprid/flumethrin collar (IVP) compared to the control product (CP) was shown if the lower limit of the two-sided 97.5% confidence interval of the difference between IVP and CP was greater than -15%.
## Methods
### Investigational Veterinary Product (IVP) and Control Product (CP)
The new imidacloprid 10%/flumethrin 4.5% collar under investigation (IVP) is a grey, odourless polymer matrix collar containing 10% (w/w) imidacloprid and 4.5% (w/w) flumethrin. The collar is designed to be fixed around the neck of cats and dogs and comes in two different sizes for dogs and one size for cats. The length of the collar can be adapted to the size of the animal with a ratchet closure mechanism and by cutting the overlapping end to the required length. Administration route, schedule, dose and dosage form of the IVP and the CP "Beaphar Ungezieferband fuer Hunde/fuer Katzen", a collar containing Dimpylat and authorised for dogs and cats for the control of flea and tick infestations in several EU countries including Germany are shown in Table Table11.
Products used and treatment regimen according to the product label requirements
### General design
Two multicentre, multiregional positive controlled clinical field studies, one in cats and one in dogs, were conducted with the IVP imidacloprid 10%/flumethrin 4.5% collar, testing the safety and efficacy in tick and flea infestations in cats and dogs for 8 months and compared to a positive control product (CP) "Beaphar Ungezieferband fuer Hunde/fuer Katzen". These clinical field studies were carried out in 33 practices/clinics, and patients were actively enrolled from different geographical areas in Europe (France, Germany, Hungary and Portugal).
The IVP collar treatment was given once during the study except in cases when the animals lost the collar and it had to be replaced, whereas the CP with its shorter label efficacy of 5 months was replaced after 5 months of wear (approx. day 140). Non-inferiority of the IVP in comparison to the CP was tested comparing baseline to post-treatment parasite counts as observed on day 2 and then every 28 days post treatment.
### Procedure
After the informed owner consent had been obtained, animals were enrolled based on predefined in- and exclusion criteria. Depending on the identified parasites they were allocated either to the flea or to the tick subgroup of the total efficacy population (per-protocol population, PP). Within the subgroups, they were randomly allocated to treatment in a ratio of 2:1 to either the IVP or the CP group. For flea infestations (an animal with at least 5 viable fleas), the primary animal of a multipet household was the experimental unit and formed part of the efficacy population (per-protocol population). Other animals of this household were treated with either the same product as the primary animal (supplementary animals) or, if contraindicated, with a product of choice of the investigator (additional animals). For tick infestations, each individual animal hosting at least 3 viable and attached ticks was enrolled and the individual animal was the experimental unit. Primary and supplementary animals of the flea part of the study together with all tick patients formed the safety population (intention-to-treat population, ITT).
Day 0 was defined individually as the day an animal was found suitable for enrolment in the study and was treated with either treatment. Study completion was the day the animal completed the study, normally day 238, unless it was previously withdrawn from the study. Animals underwent parasitological and clinical assessments on day 0 and thereafter in monthly intervals (every 4 weeks) until day 238. These intervals were treated in the statistical evaluation as "post baseline periods". All visits (except visit on day 2: ± 1 day) were performed within a range of ± 2 days of the target day.
#### Parasitological examinations
Tick and flea counts were performed by the examining veterinarian as complete body counts according to a defined procedure, using manual palpation for ticks and additional fine-toothed flea combs for fleas. Counting was terminated at 10 minutes after the last identification of a flea or tick. Parasites were collected, fixed in ethanol and stored for species determination at a later stage. The species and developmental stage of the collected ticks from dogs and cats were identified by the Department of Comparative Tropical Veterinary Medicine, LMU Munich, Germany. The identification of collected fleas was performed by Bayer Animal Health GmbH, Monheim, Germany. Both institutes conducted the identification according to approved internal Standard Operation Procedures, using a number of morphological keys, either published (such as e.g. the Catalogue of the Rothschild Collection of Fleas [20]) or unpublished, internal expert's material (such as extensive descriptions and photos).
#### Clinical and safety observations
Primary animals were observed on day 2 and monthly thereafter for clinical signs, dermatological changes at the application site and adverse events, which were then categorized into suspected adverse drug reactions (SADR) and events unrelated to treatment. Supplementary animals were observed at least once at the end of the study by the study veterinarians for changes at the application site and for adverse events. Additionally, all animals were under daily supervision of their owners who were obliged to report any adverse events, especially signs of collar side effects, to their veterinarian as soon as they appeared.
### Data handling and analysis
Data from all study animals were entered into StudyBase®, an electronic data capture solution specifically designed for animal health studies via a web browser. Software was validated prior to use. After verification of the data, they were downloaded to SAS® for analysis (SAS Institute Inc., Cary, NC, USA, version 9.2).
### Statistical analysis
The primary (overall) efficacy of the investigational veterinary product was defined as the average viable tick or flea count reduction compared to the day 0-baseline over the entire treatment period (8 months) and was compared to the control product using a test of non-inferiority corrected to baseline.
The percentage of flea and tick count reduction compared to baseline was calculated for each monthly evaluation period. Mean percentage reduction over all post-baseline periods was compared between treatment groups using a non-inferiority margin of 15%. Non-inferiority of IVP compared to CP was shown if the lower limit of the two-sided 97.5% confidence interval of the difference between IVP and CP was greater than -15%. This corresponds to the following test hypotheses:
$H0:PRIVP≤PRCP-15%HA:PRIVP>PRCP-15%$
with PRIVP resp PRCP being the least square means of percentage reduction over all post-baseline periods for the IVP compared to the CP calculated in an analysis of variance with repeated measurements adjusted for baseline (main effect of treatment over all post-baseline periods).
For calculation of the percentage parasite count reduction (PR) the following formula was used for each individual animal:
$count(period1)-count(periodi)count(period1)×100=PRatPeriodi$
for i = 2 to 11 (post-baseline evaluation periods) and period 1 = baseline.
As a secondary efficacy criterion, tick and flea count reductions (compared to baseline) were assessed separately for each single post-baseline period to evaluate superiority of the IVP compared to the control group.
Additionally the prevalence of concurrent tick and/or flea infestations was evaluated for the whole study period and the percentage of patients showing Flea Allergic Dermatitis (FAD) was calculated for each observation day.
## Results
The total safety population (intention to treat population, ITT) consisted of 400 dogs and 313 cats, of which 271 dogs and 232 cats were treated with the imidacloprid 10%/flumethrin 4.5% collar (IVP) and 129 dogs and 81 cats were treated with the CP (Table (Table2).2). The efficacy population (per protocol population, PP) consisted of 118 (IVP) + 47 (CP) cats and 197 (IVP) + 94 (CP) dogs. As common in this type of study, the number of control animals (CP group) was considerably smaller than the number of animals in the IVP group. The CP animal number was confirmed to be sufficient by the proof of statistical comparability of IVP and CP in terms of epidemiological data (gender, neutered, pure-bred, age, weight, coat length, husbandry and living place (urban or country side). All comparisons resulted positively in values between p > 0.05 up to 1.00, except one single value in the cat PP flea population (hair coat length; p = 0.048). The investigational product showed a long and reliable efficacy against fleas and ticks over the complete 8 months study period, which significantly exceeded the efficacy of the control product efficacy (except for tick efficacy in cats where superiority of the IVP was shown for months 2-4 only). A good tolerability of the IVP was shown with only a few (9% in cats/1.04% in dogs) minor local tolerance events mostly due to the mechanical influence of the collar, such as erythema, alopecia, scratching and cosmetic effects such as hair discoloration.
Study design and allocation to treatment of safety population (= Intent to Treat Population, ITT) and efficacy population (= Per Protocol Population, PP)
At enrolment, treatment groups were assessed for any differences regarding breeds, coat length, husbandry and tick and flea counts and no relevant differences were observed between groups. At enrolment (day 0), C. felis was found to be the most prevalent flea species identified in cats (96.8%) and dogs (94.0%), while C. canis (0% and 12.0%), A. erinacei (3.2% and 2.4%) and P. irritans (1.6 and 3.6%) were also identified. Tick species identified from viable ticks at day 0 in cats and dogs respectively were: D. reticulatus (1.8% and 18.4%), I. hexagonus (7.1% and 11.4%), I. ricinus (89.3% and 64.9%) and Rhipicephalus spp. (most probably turanicus/sanguineus) (8.9% and 28.1%). Other tick species identified in very low numbers included Haemaphysalis spp., I. canisuga and Ixodes spp. (Table (Table33).
Tick and flea species identified on dogs and cats (as percentage of primary IVP animals) and percentage of patients with mixed flea and tick infestation
### Efficacy
Efficacy of the imidacloprid 10%/flumethrin 4.5% collar in comparison to the control product is illustrated for cats in Figures Figures11 and and22 and for dogs in Figures Figures33 and and4.4. All calculations are based on arithmetic mean data in accordance with the EU Guideline for the testing and evaluation of the efficacy of antiparasitic substances for the treatment and prevention of tick and flea infestation in dogs and cats (EMEA/CVMP/005/2000- Rev.2).
Percentage reduction of viable fleas in cats for each efficacy evaluation period - arithmetic means and 95% confidence limits (PP population).
Percentage reduction of viable ticks in cats for each efficacy evaluation period - arithmetic means and 95% confidence limits (PP population).
Percentage reduction of viable fleas in dogs for each efficacy evaluation period - arithmetic means and 95% confidence limits (PP population).
Percentage reduction of viable ticks in dogs for each efficacy evaluation period - arithmetic means and 95% confidence limits (PP population).
#### Overall efficacy against fleas and ticks (primary efficacy criterion)
Based on the efficacy population (per protocol population) the mean percent reduction of flea counts in the IVP group was 98.4% in cats and in 96.7% dogs, whereas in the CP group it was 79.3% in cats and 57.9% in dogs for the overall study period (Table (Table4).4). The mean percent reduction of tick counts in the IVP group was 98.4% in cats and 94.7% in dogs whereas in the CP group it was 96.9% in cats and 85.6% in dogs for the overall study period (Table (Table4).4). Non-inferiority (lower 97.5% confidence interval of least square mean difference greater than -15.0) was shown for the IVP groups (cats and dogs) compared to the control groups (cats and dogs). Based on the baseline counts of all animals treated (intention-to-treat population), superiority of the imidacloprid 10%/flumethrin 4.5% groups (cats and dogs) as compared to the control product was proven.
Efficacy results based on tick and flea count reduction as compared to the baseline counts on Day 0
#### Efficacy comparison per study day for ticks and fleas (secondary efficacy criterion)
##### Efficacy at day 2 (curative efficacy)
Curative efficacy against fleas and ticks already on the animal at the timepoint of treatment (day 0) is described by the study day 2 flea and tick count reduction. For fleas, it was 92.9% and 71.8% in cats and 86.7% and 66.5% in dogs for the IVP and CP group, respectively. For ticks, it was 94.8% and 97.7% in cats and 79.9% and 86.6% in dogs for the IVP and CP group, respectively.
##### Efficacy at day evaluation time points post day 2 (preventive efficacy)
From day 28 to day 238 the IVP group reached more than 95% percent flea count reduction based on both the cat (exception day 28 (94.1%)) and the dog efficacy population whereas the control group never reached the threshold of 95% flea count reduction during the 8 months study duration. The IVP was superior to the control product at every flea count time point in dogs and cats and at various tick assessment time points (Table (Table4).4). Superiority of the imidacloprid 10%/flumethrin 4.5% collar was tested using ANOVA adjusted to baseline at p < 0.05. From day 28 to day 238 the IVP group reached more than 90% percent tick count reduction based on both the cat and the dog efficacy population whereas the control group showed values above 90% only in cats and did not reach at any time within the 8 months 90% tick count reduction in dogs.
The non-parametric Wilcoxon test confirmed the results of the ANOVA analysis.
#### Concurrent flea and tick infestations
Concurrent flea and tick infestations were observed in 3.2% and 3.5% of the dogs and cats and in 5.3% and 5.7% of the assessed households (Table (Table33).
The influence of IVP and CP treatment on FAD was evaluated for both treatment groups. In addition, to evaluate the curative efficacy of the new collar in particular, and in order not to overestimate its efficacy on FAD, the individual clinical case records of the IVP group were further investigated to evaluate the influence of palliative glucocorticoid treatments to the treatment success:
##### Cats
On the enrolment day (study day 0), 18 (7.8%) of the 231 cats in the IVP-ITT population showed symptoms of FAD. By SD 2 this number was reduced to 14 (6.1%) and FAD was completely cured at the SD 28 evaluation. Only one new case came up at SD 196. Since no further investigations were conducted in this animal, the reason/correct diagnosis cannot be definitively clarified, especially since the flea counts were zero. In the CP group, 8 (10%) out of the 80 cats in the ITT population started the study with FAD already present. FAD cases in the CP group also declined rapidly within the first 28 days after treatment to between very few to no flea allergic animals.
##### Description of palliative FAD treatment in the IVP group
Palliative treatment was not prohibited for the study animals. Only five FAD positive cats were concomitantly treated once with a glucocorticoid against FAD at SD0 in parallel to the collar application, and only one of these treatments contained a depot formulation. Of the 18 FAD cases found in the cat population, the 4 short term and one long term glucocorticoid treated cats represent 28% of this subgroup and the rest of the cases resolved without any additional treatment.
##### Dogs
On the inclusion day, 23 (8%) of the 286 dogs in the ITT population showed symptoms of FAD. By SD 2 this number was reduced to 16 (5.6%), and consequently decreased to 4 (1.4%) at SD 28. FAD completely vanished at the SD 56 evaluation, apart from one persistent case, which remained visible up to SD 168 before a full cure was achieved. At the very end of the study (SD 238), two new cases came up. Since no further investigations were conducted in these animals, the reason/correct diagnosis cannot be definitively clarified, especially since the flea counts were zero. In the CP group, 12 (8.8%) out of the 136 dogs in the ITT population started the study with FAD already present. FAD cases in the CP groups also declined rapidly within the first 28 days after treatment to between very few to no flea allergic animals.
##### Description of palliative FAD treatment in the IVP group
Only one FAD positive dog was concomitantly treated once with a short term glucocorticoid against FAD at SD0 in parallel to the collar application, moreover, one FAD positive dog at study inclusion had a history of being treated one month before collar application with a glucocorticoid. Of the 23 FAD cases found in the dog population, the one short term glucocorticoid treated animal represents 4.3% of this subgroup whereas the rest of the cases resolved without any additional treatment.
### Safety
The number of adverse events suspected to be treatment related was evaluated for both treatments and evidence was compared statistically. In cats, a total of 28 events were suspected to be related to study medication (Suspected Adverse Drug Reactions (SADRs)), 23 in the IVP (9.0% of the IVP safety population) and 5 in the control group (5.6% of the CP safety population). This difference was not statistically significant (p > 0.4; Fisher's exact test). Cat SADRs were generally mild dermal reactions (alopecia, pruritus, mild contact dermatitis).
In dogs, in the IVP group 3 events (alopecia, hair coloration, dermatitis) and in the CP group 4 events (alopecia, flea infestation, pruritus, aggressive behaviour towards a collar wearing animal) were scored as being related to the study medication. The difference between the two groups was not statistically significant (P > 0.16; Fisher's exact test)
## Discussion
### General
The two studies reported here were conducted according to VICH GCP, which assured the accurateness, integrity and correctness of the observations. The studies were controlled by a positive control group, animals were randomised to treatment groups and the laboratory scientists conducting the identification of parasites were blinded with respect to treatment group. Although the investigators counting the fleas and/or ticks could not be blinded due to the nature of the treatments, the possible influence of bias is nevertheless limited: parasite counts are an objective measure and a standard procedure was followed to guarantee accurate and comparable parasite counts at all study sites throughout the study period.
### Efficacy
The evaluated flea counts confirm the results described for imidacloprid and imidacloprid combinations by various authors [21-24]. However, the duration of efficacy against fleas of the previously licensed spot-on formulations of imidacloprid is about one month for Advantage®, Advocate® and Advantix® (Bayer Animal Health) respectively, while the collar exhibits a long-term efficacy for 8 months. The same applies to ticks, where the efficacy duration of spot on products is usually limited to 3-4 weeks, depending on tick species (Advantix®, Frontline Combo®) or, for cats is even shorter (2 weeks; Frontline Combo® cat). The therapeutic need in cats is quite evident as, apart from this product, the availability of acaricides for this species is highly limited.
Efficacy for a period of eight months had been proven as prerequisite for the field study in fleas and numerous tick species in laboratory studies reported by Stanneck et al. [10,11]. The fast onset of protective insecticidal, acaricidal and repellent efficacy (immediately in fleas, as to 24 h counts; within 48 hours in ticks) together with the reliable longterm insecticidal, acaricidal and repellent efficacy in the various European flea and tick species became evident in the course of the described laboratory work and has been confirmed now by the excellent results of the herein described field studies. This longterm efficacy is useful for full season protection in most climatic areas, where fleas and ticks exhibit a significant problem. Overgaauw [25] reports that the main problem in the control of flea and tick infestation is caused by the inadequate frequency and duration of treatments given by owners. According to Overgaauw, 62% of treatment failures are caused by inadequate treatment frequency and duration. The imidacloprid 10%/flumethrin 4.5% collar offers unique options for the easy, long-term and sustained control of fleas and ticks and may help overcome the problems of owner compliance.
### Flea allergic dermatitis
The one group of animals that is highly dependent on strict owner compliance especially for flea control are those suffering from FAD. Although any modern flea protective spot on product states on its label that treatment aids FAD control, FAD patients prescribed these products frequently suffer from the intermittent in- and decrease of flea populations due to inadvertently prolonged inter-treatment intervals caused by poor owner compliance. The imidacloprid 10%/flumethrin 4.5% collar showed in the field studies a high potential to cure and prevent FAD: out of 18 (cat) and 23 (dog) FAD cases found in the cat and dog population the 5 (cat)/1 (dog) initial glucocorticoid treated animals represent 28% (cat) and 4.3% (dog) of this subgroup whereas the rest of the cases (72% (cat) and 95.7% (dog)) resolved without any additional treatment. The FAD curative efficacy of the collar is therefore obvious, as is the protective efficacy: no further glucocorticoid treatment was necessary in this highly flea susceptible subpopulation throughout the study to prevent further FAD relapses.
Moreover, in one FAD positive dog which was treated one month before the start of the study with a glucocorticoid, obviously with limited success (FAD present at study enrolment) the FAD resolved under exclusive treatment with the imidacloprid 10%/flumethrin 4.5% collar without any further palliative treatments. The benefit of FAD treatment by the strict and sustainable flea eradication coupled with longterm continuous flea control over just palliative measures is evident.
### Safety
With the exception of local reactions at the collar site, no adverse event in either dogs or cats was evaluated as being product related. Mainly, the reported cases were slight signs of dermal irritations most probably due to mechanical rubbing as they all had one thing in common: they were generally transient and healed under the collar when the collar was left on the animal. These observations reflect the experiences made in the extensive series of up to 5 times overdosed longterm laboratory target animal safety studies in cats and dogs, kittens and puppies which were conducted as a prerequisite for conducting the field studies [12]. These studies showed that the formulation is safe for cats (from 10 weeks of age) and dogs (from 7 weeks of age) even at a 5 fold overdose and with repeated (every 2 months) applications. Particularly important was the confirmation of collar safety in the more drug sensitive species i.e. cat, especially as the collar contains flumethrin, a member of the pyrethroid class. As described in the introduction, flumethrin as an active ingredient was found and proved to be as safe in cats as in dogs. Additionally, the active ingredients are released from the collar matrix evenly and without peak concentrations [9] so that no elevated acute active ingredient exposure occurs. Having safe active ingredients in a safe, slow release formulation makes the collar an ideal application for the drug sensitive cat species and allows the use of flumethrin, a potent acaricide with fast acting, repellent properties, in a species in which it is not possible to apply any of the current pyrethroids (e.g. permethrin, deltamethrin). The undeniable safety of the collar particularly for cats was additionally underlined by its mechanical features, which were especially designed to address the particular concerns of cat owners. Cat owners may be worried about fitting collars to cats as they perceive an increased potential risk for cats to be caught or strangulated while roaming and hunting outside. The specific safety oriented design (safety closure mechanism plus a predetermined breakpoint as second fall back safety feature) will release a cat with comparably minor extra force. This is reflected by the results of the cat field study in which no such events were recorded.
### Canine vector borne diseases (CVBD)
The above described efficacy gets medical importance when it is seen in the light of the role of ectoparasites as potent vectors of bacterial, viral and protozoal diseases, as briefly outlined in the background section. Besides offering protection against the parasites themselves and the establishment of large populations (fleas, R. sanguineus ticks), an uninterrupted longterm efficacy has another important benefit; by prevention of parasite bites it also can help preventing vector borne disease transmission. This is obvious in regions with regular and high flea and especially tick infestation pressure but holds also true for regions with more occasionally occurring flea and tick infestations in which animal owners tend to rely on their own abilities in finding and removing attached ticks by hand quick enough to prevent pathogens being transmitted. This is a dangerous misinterpretation of the physiological facts. On the one hand, there is a highly underestimated parasite species which can act as fast and potent transmitters of vector borne diseases: the fleas. Besides the well known and by Europe's pet owners no longer feared plague bacteria, they carry a number of e.g. Rickettsia or Bartonella species which are in many cases zoonoses and therefore of remarkable medical impact. Especially Bartonellosis, caused by B. henselae and mainly linked to cats as a reservoir, can be regarded as one of the major potential emerging infections of man [26].
On the other hand even not all tick borne pathogens are transmitted as slowly as e.g. Babesia canis canis with the sporozoites needing a maturation of at least 48 hours in the tick's salivary glands to become infectious [27]. There are numerous diseases which are transmitted much faster (e.g. Ehrlichia canis within 4-6 hours after tick attachment) [28] and a small, attached but still unengorged female tick can be easily overlooked and so successfully transmit diseases during this early stage.
The danger of acquiring a tick borne disease is even increased by the fact that not only the easily visible adult ticks but also tick larvae and nymphs are highly important for CVBD transmission according to recent knowledge [29]. These parasites are nearly invisible because of their very small size and would not be noted or removed by the animal owner, but they are potent vectors due to horizontal transmission (larvae are infected and transfer the pathogen during moulting to the nymph stage) or even vertical transmission (an infected adult transfers the pathogen via the eggs to the next larvae/nymph generation: occurs e.g. in Borrelia, Babesia) [30]. As the number of the juvenile stages usually exceeds by far the number of adult ticks, they form a serious threat for animals exposed to their habitats. The susceptibility of tick stages against imidacloprid/flumethrin declines from larva > nymph > adult ticks. According to the European guideline EMEA/CVMP/005/2000, this is expected, but it was furthermore proven in particular during the development of the imidacloprid 10%/flumethrin 4.5% collar [9].
## Conclusion
Seresto®, an Imidacloprid 10%/Flumethrin 4.5% collar has been shown to be safe and highly efficacious in the treatment and prevention of tick and flea infestations in cats and dogs treated as patients presenting to veterinary practices under field conditions. The evaluation of efficacy was based on non-inferiority to the control group treated with a commercial product licensed for this indication. Efficacy for both tick and flea infestations was confirmed by at least 90% tick and 95% flea count reduction in cats and dogs, respectively for the whole study period. In addition, superiority of the IVP group compared to the control group was confirmed for both flea and tick count reduction at various time points.
Containing two highly potent yet safe active ingredients, the neonictinid imidacloprid and the α-cyano-pyrethroid flumethrin, the imidacloprid 10%/flumethrin 4.5% collar with its slow release formulation proved to be very safe in both dogs and cats. Especially for cats, this product provides the first longterm acaricidal and tick repellent treatment on the market.
The imidacloprid 10%/flumethrin 4.5% collar will thereby contribute markedly to the effective and safe protection of cats and dogs against ectoparasites and consequently vector borne diseases.
## Competing interests
This clinical study was completely funded by Bayer Animal Health GmbH, Monheim, Germany, thereof D. Stanneck (Germany) and C. LeSueur (France) are employees. KLIFOVET AG is an independent Contract Development Organisation, which was contracted to manage the conduct of this study. K. Hellmann is the managing director, I. Radeloff is the project manager, J. Rass an employee. All authors voluntarily publish this article and have no personal interest in this trial other than publishing the scientific findings that they have been involved in by planning, setting-up, monitoring, conducting and analysing this study.
## Authors' contributions
DS, JR, IR, CLS and KH designed the study design and protocols and JR, IR and CLS carried out the studies. DS, JR, IR, CLS and KH compiled and analysed the data and were contributing substantially to the final study reports. JR, IR and KH were responsible for the first setup up of the manuscript, which was then substantially revised by all authors. All authors read and approved the final manuscript.
## Acknowledgements
The authors are sincerely grateful to the dog and cat owners that permitted their animals to participate in this study after granting informed owner consent as well as all investigators and their staff.
## Compliance statement
This study was conducted in France, Germany, Hungary and Portugal after obtaining the express authorisation of the relevant regulatory authority of these countries. Prior to treatment of any animal an informed owner consent was obtained in writing.
## References
• Steuber S, Bode K. Kriterien für die Zulassung von Tierarzneimitteln gegen Zeckenbefall bei Hunden und Katzen: Ein Überblick der aktuellen Anforderungen und Möglichkeiten unter Berücksichtigung der derzeitig gültigen Leitlinien. J Verbr Lebensm. 2008;3:195–200. doi: 10.1007/s00003-008-0344-6.
• Pfister K. In: Veterinaermedizinische Parasitologie. Thomas Schnieder, editor. Parey: Stuttgart; 2006. Arthropodenbefall bei Hund und Katze; pp. 521–559.
• Chomel B. Tick-borne infections in dogs - an emerging infectious threat. Vet Parasitol. 2011;179(4):294–301. doi: 10.1016/j.vetpar.2011.03.040. [PubMed]
• Baggott D, Ollagnier C, Yoon S, Collidor N, Mallouk Y, Cramer L. Efficacy of a novel combination of fipronil, amitraz and (S)-methoprene for treatment and control of tick species infesting dogs in Europe. Vet Parasitol. 2011;179(4):330–334. doi: 10.1016/j.vetpar.2011.03.045. [PubMed]
• Bouhsira E, Yoon S, Roques M, Manavella C, Vermont S, Cramer L, Ollagnier C, Franc M. Efficay of fipronil, amitraz and (S)-methoprene combination spot on for dogs against adult dog fleas (Ctenocephalides canis, Curtis, 1826) Vet Parasitol. 2011;179(4):351–353. doi: 10.1016/j.vetpar.2011.03.048. [PubMed]
• Liebisch A, Schein E, Dorn H, Liebisch G. Prevention of infestation with ticks and fleas with the dog collar KILTIX. Prakt Tierarzt. 1996;77(6):493–510.
• Fourie LJ, Stanneck D, Horak IG. The efficacy of collars impregnated with flumethrin and propoxur against experimental infestations of adult Rhipicephalus sanguines on dogs. J S Afr Vet Assoc. 2003;74(4):123–126. [PubMed]
• Mehlhorn H, Mencke N, Hansen O. Effects of imidacloprid on adult and larval stages of the flea Ctenocephalides felis after in vivo and in vitro application: a light- and electron-microscopy study. Parasitol Res. 1999;85(8-9):625–637. doi: 10.1007/s004360050607. [PubMed]
• Stanneck D, Ebbinghaus-Kintscher U, Schoenhense E, Kruedewagen EM, Turberg A, Leisewitz A, Jiritschka W, Krieger KJ. The synergistic action and release kinetics of 10% imidacloprid and 4.5% flumethrin in collars applied for ectoparasite control in dogs and cats. Parasit Vectors. 2012. in press . [PubMed]
• Stanneck D, Kruedewagen EM, Fourie JJ, Horak I, Davis W, Krieger KJ. The efficacy of an imidacloprid/flumethrin collar against fleas and ticks on cats. Parasit Vectors. in press . [PubMed]
• Stanneck D, Kruedewagen EM, Fourie JJ, Horak I, Davis W, Krieger KJ. The efficacy of an imidacloprid/flumethrin collar against fleas, ticks, mites and lice on dogs. Parasit Vectors. in press . [PubMed]
• Veterinary Medicines Directorate. Summary of Product Characteristics for Seresto/Foresto. http://www.vmd.defra.gov.uk/ProductInformationDatabase/SPC_Documents/SPC_332767.doc
• Linnett P. Permethrin toxicosis in cats. Aus Vet J. 2008;86:32–35. doi: 10.1111/j.1751-0813.2007.00198.x. [PubMed]
• Meyer EK. Toxicosis in cats erroneously treated with 45 to 65% permethrin products. J Am Vet Med Assoc. 1999;5:198–203. [PubMed]
• Reid FM, Oeheme FW. In: The Cat: Diseases and Clinical Management. Sherding RG, editor. New York: Churchill Livingstone; 1989. Toxicoses; p. 190.
• Richardson JA. Permethrin spot-on toxicosis in cats. J Vet Emerg Crit Care. 2000;10:103–6. doi: 10.1111/j.1476-4431.2000.tb00006.x.
• Kaneko H. In: Handbook of Pesticide Toxicology Principles. Krieger R, editor. London, San Diego: Academic Press; 2010. Pyrethroid Chemistry and Metabolism.
• Bomann W. Bayticol acid - Investigations of subacute toxicity in Wistar rats. Bayer Internal Study Report 1995, ID 24057, Submitted to WHO.
• Kraemer F, Krieger KJ, Schmuck G, Stanneck D. Seresto® - ein neues Polymermatrix-Halsband mit denWirkstoff en Flumethrin und Imidacloprid zum Langzeitschutz von Hunden und Katzen vor Zecken- und Flohbefall. Kleintier konkret. in press http://dx.doi.org/10.1055/s-0031-1298092.
• Hopkins GEH, Rothschild M. An Illustrated Catalogue of the Rothschild Collection of Fleas (Siphonaptera) in the British Museum (Natural History) with Keys and Short Descriptions for the Identification of Families, Genera, Species and Subspecies. Vol. I. Tungidae and Pulicidae. London: Trustees of the British Museum; 1953.
• Arther RG, Cunningham J, Dorn H, Everett R, Herr LG, Hopkins T. Efficacy of imidacloprid for removal and control of fleas (Ctenocephalides felis), on dogs. Am J Vet Res. 1997;58:848–850. [PubMed]
• Arther RG, Bowman DD, McCall JW, Hansen O, Young DR. Feline Advantage Heart ™(Imidacloprid and Moxidectin) topical solution as monthly treatment for prevention of heartworm infection (Dirofilaria immitis) and control of fleas (Ctenocephalides felis) on cats. Parasitol Res. 2003;90:137–139. doi: 10.1007/s00436-003-0917-3. [PubMed]
• Epe C, Coati N, Stanneck D. Efficacy of the compound preparation imidacloprid 10% (w/v)/Permethrin 50% (w/v) spot-on against ticks (I. ricinus, R. sanguineus) and fleas (C. felis) on dogs. Parasitol Res. 2003;90:123–124. [PubMed]
• Hellmann K, Knoppe T, Krieger K, Stanneck D. European multicenter field trial on the efficacy and safety of a topical formulation of imidacloprid and permethrin (Advantix™) in dogs naturally infested with ticks and/or fleas. Parasitol Res. 2003;90:125–126. doi: 10.1007/s00436-003-0912-8. [PubMed]
• Overgaauw P. Frontline Combo sucht die Schutzpraxis 2011. Kleintierpraxis. 2011;56:504.
• Day MJ. One health: the importance of companion animal vector-borne diseases. Parasit Vectors. 2011;4:49. doi: 10.1186/1756-3305-4-49. doi:10.1186/1756-3305-4-49. [PubMed]
• Heile C, Hoffmann-Köhler P, Wiemann A, Schein E. Transmission time of tick-borne disease agents in dogs: Borrelia, Anaplasma, Ehrlichia and Babesia. Prakt Tierarzt. 2007;88:584–590.
• Katavolos P, Armstrong PM, Dawson JE. et al. Duration of tick attachment required for transmission of granulocytic ehrlichiosis. J Infect Dis. 1998;177:1422–1425. doi: 10.1086/517829. [PubMed]
• Otranto D, Lia RP, Cantacessi C, Galli G, Paradies P, Mallia E, Capelli G. Efficacy of a combination of imidacloprid 10%/permethrin 50% versus fipronil 10%/(S)-methoprene 12%, against ticks in naturally infected dogs. Vet Par. 2005;130(3-4):293–304. doi: 10.1016/j.vetpar.2005.04.014. [PubMed]
• Lane RS, Burgdorfer W. Transovarial and Transstadial Passage of Borrelia burgdorferi in the Western Black-Legged Tick, Ixodes pacificus (Acari: Ixodidae) Am J Trop Med Hyg. 1987;37:188–192. [PubMed]
Articles from Parasites & Vectors are provided here courtesy of BioMed Central
## Formats:
### Related citations in PubMed
See reviews...See all...
See all...
|
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 2, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "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": 0.41009658575057983, "perplexity": 10073.890638210745}, "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-2014-35/segments/1409535919066.8/warc/CC-MAIN-20140901014519-00049-ip-10-180-136-8.ec2.internal.warc.gz"}
|
http://pointclouds.org/documentation/tutorials/vfh_recognition.php
|
Cluster Recognition and 6DOF Pose Estimation using VFH descriptors
As previously described in Estimating VFH signatures for a set of points, Viewpoint Feature Histograms (VFH) are powerful meta-local descriptors, created for the purpose of recognition and pose estimation for clusters of points. We here refer to a cluster as a collection of 3D points, most of the time representing a particular object or part of a scene, obtained through some segmentation or detection mechanisms (please see Euclidean Cluster Extraction for an example).
Our goal here is not to provide an ultimate recognition tool, but rather a mechanism for obtaining candidates that could potentially be the cluster/object that is searched for, together with its 6DOF pose in space. With this in mind, we will be formulating the recognition problem as a nearest neighbor estimation problem. So given a set of training data, we will use efficient nearest neighbor search structures such as kd-trees and return a set of potential candidates with sorted distances to the query object, rather than an absolute “this is the object that we were searching for” kind of response. The reader can imagine that such a system becomes much more useful as we can explicitly reason about failures (false positives, or true negatives).
For the purpose of this tutorial, the application example could be formulated as follows:
• Training stage:
• given a scene with 1 object that is easily separable as a cluster;
• use a ground-truth system to obtain its pose (see the discussion below);
• rotate around the object or rotate the object with respect to the camera, and compute a VFH descriptor for each view;
• store the views, and build a kd-tree representation.
• Testing stage:
• given a scene with objects that can be separated as individual clusters, first extract the clusters;
• for each cluster, compute a VFH descriptor from the current camera position;
• use the VFH descriptor to search for candidates in the trained kd-tree.
We hope the above makes sense. Basically we’re first going to create the set of objects that we try to later on recognize, and then we will use that to obtain valid candidates for objects in the scene.
A good example of a ground-truth system could be a simple rotating pan-tilt unit such as the one in the figure below. Placing an object on the unit, and moving it with some increments in both horizontal and vertical, can result in a perfect ground-truth system for small objects. A cheaper solution could be to use a marker-based system (e.g., checkerboard) and rotate the camera/table manually.
Our Kd-Tree implementation of choice for the purpose of this tutorial is of course, FLANN.
Training
We begin the training by assuming that the objects are already separated as individual clusters (see Euclidean Cluster Extraction), as shown in the figure below:
Since we’re only trying to cover the explicit training/testing of VFH signatures in this tutorial, we provide a set of datasets already collected at: vfh_recognition_tutorial_data.tbz. The data is a subset of the objects presented in the figure below (left), and look like the point clouds on the right. We used the pan-tilt table shown above to acquire the data.
Next, copy and paste the following code into your editor and save it as build_tree.cpp.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 #include #include #include #include #include #include #include #include #include typedef std::pair > vfh_model; /** \brief Loads an n-D histogram file as a VFH signature * \param path the input file name * \param vfh the resultant VFH model */ bool loadHist (const boost::filesystem::path &path, vfh_model &vfh) { int vfh_idx; // Load the file as a PCD try { pcl::PCLPointCloud2 cloud; int version; Eigen::Vector4f origin; Eigen::Quaternionf orientation; pcl::PCDReader r; int type; unsigned int idx; r.readHeader (path.string (), cloud, origin, orientation, version, type, idx); vfh_idx = pcl::getFieldIndex (cloud, "vfh"); if (vfh_idx == -1) return (false); if ((int)cloud.width * cloud.height != 1) return (false); } catch (const pcl::InvalidConversionException&) { return (false); } // Treat the VFH signature as a single Point Cloud pcl::PointCloud point; pcl::io::loadPCDFile (path.string (), point); vfh.second.resize (308); std::vector fields; pcl::getFieldIndex (point, "vfh", fields); for (size_t i = 0; i < fields[vfh_idx].count; ++i) { vfh.second[i] = point.points[0].histogram[i]; } vfh.first = path.string (); return (true); } /** \brief Load a set of VFH features that will act as the model (training data) * \param argc the number of arguments (pass from main ()) * \param argv the actual command line arguments (pass from main ()) * \param extension the file extension containing the VFH features * \param models the resultant vector of histogram models */ void loadFeatureModels (const boost::filesystem::path &base_dir, const std::string &extension, std::vector &models) { if (!boost::filesystem::exists (base_dir) && !boost::filesystem::is_directory (base_dir)) return; for (boost::filesystem::directory_iterator it (base_dir); it != boost::filesystem::directory_iterator (); ++it) { if (boost::filesystem::is_directory (it->status ())) { std::stringstream ss; ss << it->path (); pcl::console::print_highlight ("Loading %s (%lu models loaded so far).\n", ss.str ().c_str (), (unsigned long)models.size ()); loadFeatureModels (it->path (), extension, models); } if (boost::filesystem::is_regular_file (it->status ()) && boost::filesystem::extension (it->path ()) == extension) { vfh_model m; if (loadHist (base_dir / it->path ().filename (), m)) models.push_back (m); } } } int main (int argc, char** argv) { if (argc < 2) { PCL_ERROR ("Need at least two parameters! Syntax is: %s [model_directory] [options]\n", argv[0]); return (-1); } std::string extension (".pcd"); transform (extension.begin (), extension.end (), extension.begin (), (int(*)(int))tolower); std::string kdtree_idx_file_name = "kdtree.idx"; std::string training_data_h5_file_name = "training_data.h5"; std::string training_data_list_file_name = "training_data.list"; std::vector models; // Load the model histograms loadFeatureModels (argv[1], extension, models); pcl::console::print_highlight ("Loaded %d VFH models. Creating training data %s/%s.\n", (int)models.size (), training_data_h5_file_name.c_str (), training_data_list_file_name.c_str ()); // Convert data into FLANN format flann::Matrix data (new float[models.size () * models[0].second.size ()], models.size (), models[0].second.size ()); for (size_t i = 0; i < data.rows; ++i) for (size_t j = 0; j < data.cols; ++j) data[i][j] = models[i].second[j]; // Save data to disk (list of models) flann::save_to_file (data, training_data_h5_file_name, "training_data"); std::ofstream fs; fs.open (training_data_list_file_name.c_str ()); for (size_t i = 0; i < models.size (); ++i) fs << models[i].first << "\n"; fs.close (); // Build the tree index and save it to disk pcl::console::print_error ("Building the kdtree index (%s) for %d elements...\n", kdtree_idx_file_name.c_str (), (int)data.rows); flann::Index > index (data, flann::LinearIndexParams ()); //flann::Index > index (data, flann::KDTreeIndexParams (4)); index.buildIndex (); index.save (kdtree_idx_file_name); delete[] data.ptr (); return (0); }
In the following paragraphs we will explain what the above code does (or should do). We’ll begin with the main function.
We begin by loading a set of feature models from a directory given as the first command line argument (see details for running the example below). The loadFeatureModels method does nothing but recursively traverse a set of directories and subdirectories, and loads in all .PCD files it finds. In loadFeatureModels, we call loadHist, which will attempt to open each PCD file found, read its header, and check whether it contains a VFH signature or not. Together with the VFH signature we also store the PCD file name into a vfh_model pair.
Once all VFH features have been loaded, we convert them to FLANN format, using:
// Convert data into FLANN format
flann::Matrix<float> data (new float[models.size () * models[0].second.size ()], models.size (), models[0].second.size ());
for (size_t i = 0; i < data.rows; ++i)
for (size_t j = 0; j < data.cols; ++j)
data[i][j] = models[i].second[j];
Since we’re lazy, and we want to use this data (and not reload it again by crawling the directory structure in the testing phase), we dump the data to disk:
// Save data to disk (list of models)
flann::save_to_file (data, training_data_h5_file_name, "training_data");
std::ofstream fs;
fs.open (training_data_list_file_name.c_str ());
for (size_t i = 0; i < models.size (); ++i)
fs << models[i].first << "\n";
fs.close ();
Finally, we create the KdTree, and save its structure to disk:
pcl::console::print_error ("Building the kdtree index (%s) for %d elements...\n", kdtree_idx_file_name.c_str (), (int)data.rows);
flann::Index<flann::ChiSquareDistance<float> > index (data, flann::LinearIndexParams ());
//flann::Index<flann::ChiSquareDistance<float> > index (data, flann::KDTreeIndexParams (4));
index.buildIndex ();
index.save (kdtree_idx_file_name);
Here we will use a LinearIndex, which does a brute-force search using a Chi-Square distance metric (see [VFH] for more information). For building a proper kd-tree, comment line 1 and uncomment line 2 in the code snippet above. The most important difference between a LinearIndex and a KDTreeIndex in FLANN is that the KDTree will be much faster, while producing approximate nearest neighbor results, rather than absolute.
So, we’re done with training. To summarize:
1. we crawled a directory structure, looked at all the .PCD files we found, tested them whether they are VFH signatures and loaded them in memory;
2. we converted the data into FLANN format and dumped it to disk;
3. we built a kd-tree structure and dumped it to disk.
Testing
In the testing phase, we will illustrate how the system works by randomly loading one of the files used in the training phase (feel free to supply your own file here!), and checking the results of the tree.
Begin by copying and pasting the following code into your editor and save it as nearest_neighbors.cpp.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 #include #include #include #include #include #include #include #include #include #include #include #include typedef std::pair > vfh_model; /** \brief Loads an n-D histogram file as a VFH signature * \param path the input file name * \param vfh the resultant VFH model */ bool loadHist (const boost::filesystem::path &path, vfh_model &vfh) { int vfh_idx; // Load the file as a PCD try { pcl::PCLPointCloud2 cloud; int version; Eigen::Vector4f origin; Eigen::Quaternionf orientation; pcl::PCDReader r; int type; unsigned int idx; r.readHeader (path.string (), cloud, origin, orientation, version, type, idx); vfh_idx = pcl::getFieldIndex (cloud, "vfh"); if (vfh_idx == -1) return (false); if ((int)cloud.width * cloud.height != 1) return (false); } catch (const pcl::InvalidConversionException&) { return (false); } // Treat the VFH signature as a single Point Cloud pcl::PointCloud point; pcl::io::loadPCDFile (path.string (), point); vfh.second.resize (308); std::vector fields; getFieldIndex (point, "vfh", fields); for (size_t i = 0; i < fields[vfh_idx].count; ++i) { vfh.second[i] = point.points[0].histogram[i]; } vfh.first = path.string (); return (true); } /** \brief Search for the closest k neighbors * \param index the tree * \param model the query model * \param k the number of neighbors to search for * \param indices the resultant neighbor indices * \param distances the resultant neighbor distances */ inline void nearestKSearch (flann::Index > &index, const vfh_model &model, int k, flann::Matrix &indices, flann::Matrix &distances) { // Query point flann::Matrix p = flann::Matrix(new float[model.second.size ()], 1, model.second.size ()); memcpy (&p.ptr ()[0], &model.second[0], p.cols * p.rows * sizeof (float)); indices = flann::Matrix(new int[k], 1, k); distances = flann::Matrix(new float[k], 1, k); index.knnSearch (p, indices, distances, k, flann::SearchParams (512)); delete[] p.ptr (); } /** \brief Load the list of file model names from an ASCII file * \param models the resultant list of model name * \param filename the input file name */ bool loadFileList (std::vector &models, const std::string &filename) { ifstream fs; fs.open (filename.c_str ()); if (!fs.is_open () || fs.fail ()) return (false); std::string line; while (!fs.eof ()) { getline (fs, line); if (line.empty ()) continue; vfh_model m; m.first = line; models.push_back (m); } fs.close (); return (true); } int main (int argc, char** argv) { int k = 6; double thresh = DBL_MAX; // No threshold, disabled by default if (argc < 2) { pcl::console::print_error ("Need at least three parameters! Syntax is: %s [options] {kdtree.idx} {training_data.h5} {training_data.list}\n", argv[0]); pcl::console::print_info (" where [options] are: -k = number of nearest neighbors to search for in the tree (default: "); pcl::console::print_value ("%d", k); pcl::console::print_info (")\n"); pcl::console::print_info (" -thresh = maximum distance threshold for a model to be considered VALID (default: "); pcl::console::print_value ("%f", thresh); pcl::console::print_info (")\n\n"); return (-1); } std::string extension (".pcd"); transform (extension.begin (), extension.end (), extension.begin (), (int(*)(int))tolower); // Load the test histogram std::vector pcd_indices = pcl::console::parse_file_extension_argument (argc, argv, ".pcd"); vfh_model histogram; if (!loadHist (argv[pcd_indices.at (0)], histogram)) { pcl::console::print_error ("Cannot load test file %s\n", argv[pcd_indices.at (0)]); return (-1); } pcl::console::parse_argument (argc, argv, "-thresh", thresh); // Search for the k closest matches pcl::console::parse_argument (argc, argv, "-k", k); pcl::console::print_highlight ("Using "); pcl::console::print_value ("%d", k); pcl::console::print_info (" nearest neighbors.\n"); std::string kdtree_idx_file_name = "kdtree.idx"; std::string training_data_h5_file_name = "training_data.h5"; std::string training_data_list_file_name = "training_data.list"; std::vector models; flann::Matrix k_indices; flann::Matrix k_distances; flann::Matrix data; // Check if the data has already been saved to disk if (!boost::filesystem::exists ("training_data.h5") || !boost::filesystem::exists ("training_data.list")) { pcl::console::print_error ("Could not find training data models files %s and %s!\n", training_data_h5_file_name.c_str (), training_data_list_file_name.c_str ()); return (-1); } else { loadFileList (models, training_data_list_file_name); flann::load_from_file (data, training_data_h5_file_name, "training_data"); pcl::console::print_highlight ("Training data found. Loaded %d VFH models from %s/%s.\n", (int)data.rows, training_data_h5_file_name.c_str (), training_data_list_file_name.c_str ()); } // Check if the tree index has already been saved to disk if (!boost::filesystem::exists (kdtree_idx_file_name)) { pcl::console::print_error ("Could not find kd-tree index in file %s!", kdtree_idx_file_name.c_str ()); return (-1); } else { flann::Index > index (data, flann::SavedIndexParams ("kdtree.idx")); index.buildIndex (); nearestKSearch (index, histogram, k, k_indices, k_distances); } // Output the results on screen pcl::console::print_highlight ("The closest %d neighbors for %s are:\n", k, argv[pcd_indices[0]]); for (int i = 0; i < k; ++i) pcl::console::print_info (" %d - %s (%d) with a distance of: %f\n", i, models.at (k_indices[0][i]).first.c_str (), k_indices[0][i], k_distances[0][i]); // Load the results pcl::visualization::PCLVisualizer p (argc, argv, "VFH Cluster Classifier"); int y_s = (int)floor (sqrt ((double)k)); int x_s = y_s + (int)ceil ((k / (double)y_s) - y_s); double x_step = (double)(1 / (double)x_s); double y_step = (double)(1 / (double)y_s); pcl::console::print_highlight ("Preparing to load "); pcl::console::print_value ("%d", k); pcl::console::print_info (" files ("); pcl::console::print_value ("%d", x_s); pcl::console::print_info ("x"); pcl::console::print_value ("%d", y_s); pcl::console::print_info (" / "); pcl::console::print_value ("%f", x_step); pcl::console::print_info ("x"); pcl::console::print_value ("%f", y_step); pcl::console::print_info (")\n"); int viewport = 0, l = 0, m = 0; for (int i = 0; i < k; ++i) { std::string cloud_name = models.at (k_indices[0][i]).first; boost::replace_last (cloud_name, "_vfh", ""); p.createViewPort (l * x_step, m * y_step, (l + 1) * x_step, (m + 1) * y_step, viewport); l++; if (l >= x_s) { l = 0; m++; } pcl::PCLPointCloud2 cloud; pcl::console::print_highlight (stderr, "Loading "); pcl::console::print_value (stderr, "%s ", cloud_name.c_str ()); if (pcl::io::loadPCDFile (cloud_name, cloud) == -1) break; // Convert from blob to PointCloud pcl::PointCloud cloud_xyz; pcl::fromPCLPointCloud2 (cloud, cloud_xyz); if (cloud_xyz.points.size () == 0) break; pcl::console::print_info ("[done, "); pcl::console::print_value ("%d", (int)cloud_xyz.points.size ()); pcl::console::print_info (" points]\n"); pcl::console::print_info ("Available dimensions: "); pcl::console::print_value ("%s\n", pcl::getFieldsList (cloud).c_str ()); // Demean the cloud Eigen::Vector4f centroid; pcl::compute3DCentroid (cloud_xyz, centroid); pcl::PointCloud::Ptr cloud_xyz_demean (new pcl::PointCloud); pcl::demeanPointCloud (cloud_xyz, centroid, *cloud_xyz_demean); // Add to renderer* p.addPointCloud (cloud_xyz_demean, cloud_name, viewport); // Check if the model found is within our inlier tolerance std::stringstream ss; ss << k_distances[0][i]; if (k_distances[0][i] > thresh) { p.addText (ss.str (), 20, 30, 1, 0, 0, ss.str (), viewport); // display the text with red // Create a red line pcl::PointXYZ min_p, max_p; pcl::getMinMax3D (*cloud_xyz_demean, min_p, max_p); std::stringstream line_name; line_name << "line_" << i; p.addLine (min_p, max_p, 1, 0, 0, line_name.str (), viewport); p.setShapeRenderingProperties (pcl::visualization::PCL_VISUALIZER_LINE_WIDTH, 5, line_name.str (), viewport); } else p.addText (ss.str (), 20, 30, 0, 1, 0, ss.str (), viewport); // Increase the font size for the score* p.setShapeRenderingProperties (pcl::visualization::PCL_VISUALIZER_FONT_SIZE, 18, ss.str (), viewport); // Add the cluster name p.addText (cloud_name, 20, 10, cloud_name, viewport); } // Add coordianate systems to all viewports p.addCoordinateSystem (0.1, "global", 0); p.spin (); return (0); }
The above code snippet is slightly larger, because we also included some visualization routines and some other “eye candy” stuff.
In lines:
std::vector<int> pcd_indices = pcl::console::parse_file_extension_argument (argc, argv, ".pcd");
vfh_model histogram;
{
pcl::console::print_error ("Cannot load test file %s\n", argv[pcd_indices.at (0)]);
return (-1);
}
pcl::console::parse_argument (argc, argv, "-thresh", thresh);
// Search for the k closest matches
pcl::console::parse_argument (argc, argv, "-k", k);
pcl::console::print_highlight ("Using "); pcl::console::print_value ("%d", k); pcl::console::print_info (" nearest neighbors.\n");
we load the first given user histogram (and ignore the rest). Then we proceed at checking two command line parameters, namely -k which will define how many nearest neighbors to check and display on screen, and -thresh which defines a maximum distance metric after which we will start displaying red lines (i.e., crossing) over the k models found on screen (eye candy!).
In lines:
loadFileList (models, training_data_list_file_name);
we load the training data from disk, together with the list of file names that we previously stored in build_tree.cpp. Then, we read the kd-tree and rebuild the index:
flann::Index<flann::ChiSquareDistance<float> > index (data, flann::SavedIndexParams ("kdtree.idx"));
index.buildIndex ();
Here we need to make sure that we use the exact distance metric (ChiSquareDistance in this case), as the one that we used while creating the tree. The most important part of the code comes here:
nearestKSearch (index, histogram, k, k_indices, k_distances);
Inside nearestKSearch, we first convert the query point to FLANN format:
flann::Matrix<float> p = flann::Matrix<float>(new float[model.second.size ()], 1, model.second.size ());
memcpy (&p.ptr ()[0], &model.second[0], p.cols * p.rows * sizeof (float));
Followed by obtaining the resultant nearest neighbor indices and distances for the query in:
indices = flann::Matrix<int>(new int[k], 1, k);
distances = flann::Matrix<float>(new float[k], 1, k);
index.knnSearch (p, indices, distances, k, flann::SearchParams (512));
Lines:
index.buildIndex ();
nearestKSearch (index, histogram, k, k_indices, k_distances);
}
// Output the results on screen
pcl::console::print_highlight ("The closest %d neighbors for %s are:\n", k, argv[pcd_indices[0]]);
for (int i = 0; i < k; ++i)
pcl::console::print_info (" %d - %s (%d) with a distance of: %f\n",
i, models.at (k_indices[0][i]).first.c_str (), k_indices[0][i], k_distances[0][i]);
pcl::visualization::PCLVisualizer p (argc, argv, "VFH Cluster Classifier");
int y_s = (int)floor (sqrt ((double)k));
int x_s = y_s + (int)ceil ((k / (double)y_s) - y_s);
double x_step = (double)(1 / (double)x_s);
create a PCLVisualizer object, and sets up a set of different viewports (e.g., splits the screen into different chunks), which will be enabled in:
p.createViewPort (l * x_step, m * y_step, (l + 1) * x_step, (m + 1) * y_step, viewport);
Using the file names representing the models that we previously obtained in loadFileList, we proceed at loading the model file names using:
pcl::PCLPointCloud2 cloud;
if (pcl::io::loadPCDFile (cloud_name, cloud) == -1)
break;
// Convert from blob to PointCloud
pcl::PointCloud<pcl::PointXYZ> cloud_xyz;
pcl::fromPCLPointCloud2 (cloud, cloud_xyz);
For visualization purposes, we demean the point cloud by computing its centroid and then subtracting it:
Eigen::Vector4f centroid;
pcl::compute3DCentroid (cloud_xyz, centroid);
pcl::PointCloud<pcl::PointXYZ>::Ptr cloud_xyz_demean (new pcl::PointCloud<pcl::PointXYZ>);
pcl::demeanPointCloud<pcl::PointXYZ> (cloud_xyz, centroid, *cloud_xyz_demean);
Finally we check if the distance obtained by nearestKSearch is larger than the user given threshold, and if it is, we display a red line over the cloud that is being rendered in the viewport:
// Create a red line
pcl::PointXYZ min_p, max_p;
pcl::getMinMax3D (*cloud_xyz_demean, min_p, max_p);
std::stringstream line_name;
line_name << "line_" << i;
p.addLine (min_p, max_p, 1, 0, 0, line_name.str (), viewport);
p.setShapeRenderingProperties (pcl::visualization::PCL_VISUALIZER_LINE_WIDTH, 5, line_name.str (), viewport);
Compiling and running the code
Create a new CMakeLists.txt file, and put the following content into it
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 cmake_minimum_required(VERSION 2.8 FATAL_ERROR) project(vfh_cluster_classifier) find_package(PCL 1.2 REQUIRED) include_directories(${PCL_INCLUDE_DIRS}) link_directories(${PCL_LIBRARY_DIRS}) add_definitions(${PCL_DEFINITIONS}) find_package(HDF5 REQUIRED) find_package(FLANN REQUIRED) include_directories(SYSTEM${HDF5_INCLUDE_DIR} ) add_executable(build_tree build_tree.cpp) target_link_libraries(build_tree ${PCL_LIBRARIES}${Boost_LIBRARIES} FLANN::FLANN ${HDF5_hdf5_LIBRARY}) add_executable(nearest_neighbors nearest_neighbors.cpp) target_link_libraries(nearest_neighbors${PCL_LIBRARIES} ${Boost_LIBRARIES} FLANN::FLANN${HDF5_hdf5_LIBRARY})
Note
If you are running this tutorial on Windows, you have to install (HDF5 1.8.7 Shared Library). If CMake is not able to find HDF5, you can manually supply the include directory in HDF5_INCLUDE_DIR variable and the full path of hdf5dll.lib in HDF5_hdf5_LIBRARY variable. Make sure that the needed dlls are in the same folder as the executables.
The above assumes that your two source files (build_tree.cpp and nearest_neighbors.cpp) are stored into the src/ subdirectory.
Then, make sure that the datasets you downloaded (vfh_recognition_tutorial_data.tbz) are unpacked in this directory, thus creating a data/ subdirectory.
After you have made the executable, you can run them like so:
$./build/build_tree data/ You should see the following output on screen: > Loading data/001.324.25 (0 models loaded so far). > Loading data/800.919.49 (13 models loaded so far). > Loading data/100.922.16 (27 models loaded so far). > Loading data/901.125.07 (47 models loaded so far). > Loading data/000.580.67 (65 models loaded so far). > Loading data/463.156.00 (81 models loaded so far). > Loading data/401.431.44 (97 models loaded so far). > Loading data/100.919.00 (113 models loaded so far). > Loading data/401.324.52 (134 models loaded so far). > Loading data/201.327.78 (150 models loaded so far). > Loading data/300.151.23 (166 models loaded so far). > Loading data/200.921.07 (180 models loaded so far). > Loaded 195 VFH models. Creating training data training_data.h5/training_data.list. Building the kdtree index (kdtree.idx) for 195 elements... The above crawled the data/ subdirectory, and created a kd-tree with 195 entries. To run the nearest neighbor testing example, you have two options: 1. Either run the following command manually, and select one of the datasets that we provided as a testing sample, like this: ./build/nearest_neighbors -k 16 -thresh 50 data/000.580.67/1258730231333_cluster_0_nxyz_vfh.pcd 2. Or, if you are on a linux system, you can place the following on a bash script file (e.g., test.sh): #!/bin/bash # Example directory containing _vfh.pcd files DATA=data # Inlier distance threshold thresh=50 # Get the closest K nearest neighbors k=16 for i in find$DATA -type d -name "*"
do
echo $i for j in find$i -type f $$-iname "*cluster*_vfh.pcd"$$ | sort -R
do
echo $j ./build/nearest_neighbors -k$k -thresh $thresh$j -cam "0.403137,0.868471/0,0,0/-0.0932051,-0.201608,-0.518939/-0.00471487,-0.931831,0.362863/1464,764/6,72"
done
done
and run the script like this:
bash test.sh
You should see recognition examples like the ones shown below:
|
{"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": 1, "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": 0.47943028807640076, "perplexity": 8685.372608930036}, "config": {"markdown_headings": false, "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-2019-22/segments/1558232261326.78/warc/CC-MAIN-20190527045622-20190527071622-00015.warc.gz"}
|
https://arxiv.org/abs/1403.6600
|
cs.NE
(what is this?)
# Title: How Crossover Speeds Up Building-Block Assembly in Genetic Algorithms
Authors: Dirk Sudholt
Abstract: We re-investigate a fundamental question: how effective is crossover in Genetic Algorithms in combining building blocks of good solutions? Although this has been discussed controversially for decades, we are still lacking a rigorous and intuitive answer. We provide such answers for royal road functions and OneMax, where every bit is a building block. For the latter we show that using crossover makes every ($\mu$+$\lambda$) Genetic Algorithm at least twice as fast as the fastest evolutionary algorithm using only standard bit mutation, up to small-order terms and for moderate $\mu$ and $\lambda$. Crossover is beneficial because it effectively turns fitness-neutral mutations into improvements by combining the right building blocks at a later stage. Compared to mutation-based evolutionary algorithms, this makes multi-bit mutations more useful. Introducing crossover changes the optimal mutation rate on OneMax from $1/n$ to $(1+\sqrt{5})/2 \cdot 1/n \approx 1.618/n$. This holds both for uniform crossover and $k$-point crossover. Experiments and statistical tests confirm that our findings apply to a broad class of building-block functions.
Subjects: Neural and Evolutionary Computing (cs.NE); Data Structures and Algorithms (cs.DS) Cite as: arXiv:1403.6600 [cs.NE] (or arXiv:1403.6600v2 [cs.NE] for this version)
## Submission history
From: Dirk Sudholt [view email]
[v1] Wed, 26 Mar 2014 09:28:56 GMT (739kb,D)
[v2] Wed, 26 Nov 2014 11:46:21 GMT (460kb,D)
|
{"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": 0, "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": 0.8440337181091309, "perplexity": 4486.04209256231}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "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-2016-44/segments/1476988721606.94/warc/CC-MAIN-20161020183841-00395-ip-10-171-6-4.ec2.internal.warc.gz"}
|
https://poidsdesante.com/south-cotabato/how-to-reduce-large-fractions-to-lowest-terms.php
|
## How to reduce (simplify) fraction 48/60 to lowest terms
Reducing fractions to lowest terms. MrExcel. 12/10/2011В В· How To Reduce Fractions To Lowest Terms-Step By Step Math Lesson - Duration: This tutorial demonstrates how to reduce a fraction to lowest terms by using multiplication and cancellation, 02/09/2019В В· There is an algorithm based on an identity accredited to Euclid. Thus, in computer programming it is called the Euclidean algorithm. Euclidean algorithm - Wikipedia Start by noting the numerator and denominator for later. Take note of which is lar....
### Reduce the Fractions to its Lowest Terms Review S1
Reducing fractions to lowest terms. MrExcel. Regardless of which manual method you choose, using them to reduce fractions can be extremely tedious and time-consuming. Therefore I would suggest you bookmark the fraction reducer calculator and use it any time you are working with fractions. How to Convert Improper Fraction to Mixed Number, fractions worksheet reduce to lowest terms worksheets simplifying pdf 6th grade.. collection of free printable math worksheets reducing fractions simplifying worksheet pdf with answers improper,simplifying fractions worksheets pdf reduce to lowest terms 5 worksheet grade 3,reducing improper fractions worksheet pdf kindergarten grade simplifying 5th worksheets,simplifying fractions ….
04/08/2010В В· Example: reduce to lowest terms the fraction 169187 / 177628. The method is called the Euclidean Algorithm. It finds the biggest number which divides into both the numerator and denominator. First you divide the bottom into the top. In this case it goes in 0 times with a remainder of 169187. You just studied 11 terms! Now up your study game with Learn mode.
We reduce a fraction to lowest terms by finding an equivalent fraction in which the numerator and denominator are as small as possible. This means that there is no number, except 1, that can be divided evenly into both the numerator and the denominator. To reduce a В· Reducing fractions 30/01/2013В В· Some fractions have HUGE numerators and denominators. Here's a way to break it down into smaller, more managable reducing steps.
04/08/2010В В· Example: reduce to lowest terms the fraction 169187 / 177628. The method is called the Euclidean Algorithm. It finds the biggest number which divides into both the numerator and denominator. First you divide the bottom into the top. In this case it goes in 0 times with a remainder of 169187. 30/01/2013В В· Some fractions have HUGE numerators and denominators. Here's a way to break it down into smaller, more managable reducing steps.
The numerator and denominator have no common factors, so the fraction is already in lowest terms. Practice questions. Increase the terms of the fraction 2/3 so that the denominator is 18. Increase the terms of 4/9, changing the denominator to 54. Reduce the fraction 12/60 to … 29/03/2014 · One of the basic reasons why we reduce fraction to lowest terms is to lessen the burden of calculating large numbers. Of course, we would rather add or multiply and than and .So you see, the effort of multiplying the same fraction is lessen when they are reduced to lowest terms.
24/04/2017 · The directions of many worksheets, quizzes and tests will ask for fractions in their simplest form. To simplify a fraction, divide the top number, known as the numerator, and the bottom number, the denominator, by the greatest common factor.The GFC is the largest number that will divide into the numerator and denominator evenly. 23/05/2017 · I suppose you’re asking about converting a ordinary positive fraction like $\frac{49}{91}$ to lowest terms, in this case $\frac7{13}$. If the numerator and denominator are small numbers, as in $\frac{10}{12}$, you
17/06/2010В В· An important part of fraction learning is understanding how to reduce a fraction to its lowest terms. When a fraction is in lowest terms, the numerator and denominator don't share any common factors. Help your fourth grader wrap his head around reducing fractions with this helpful worksheet. Need more help? Try Reducing to Lowest Terms #2. 18/07/2012В В· Reducing a Fraction to Lowest Terms. Here I look at reducing a fraction to lowest terms. I do not take the shortest route, but show how I often perform the simplification if no one is watching!
### What are some ways to reduce large fractions? Quora
Fractions Worksheet Reduce To Lowest Terms Worksheets. 29/03/2014 · One of the basic reasons why we reduce fraction to lowest terms is to lessen the burden of calculating large numbers. Of course, we would rather add or multiply and than and .So you see, the effort of multiplying the same fraction is lessen when they are reduced to lowest terms., 23/05/2017 · I suppose you’re asking about converting a ordinary positive fraction like $\frac{49}{91}$ to lowest terms, in this case $\frac7{13}$. If the numerator and denominator are small numbers, as in $\frac{10}{12}$, you.
### Tips for reducing fractions with large numbers YouTube
How to reduce (simplify) fraction 18/6 to lowest terms. 30/01/1998В В· Reducing Fractions with Large Numbers Date: 01/30/98 at 09:37:30 From: Pat Subject: Reducing fractions Dear Dr. Math, A neighborhood child asked for help with a math problem involving reducing fractions. 20904/12 = 1742, so, reduced to lowest terms, 20904/52740 = 1742/4395. This always works, and always gives the largest common factor To reduce any fraction, we have to determine factors of its numerator (upper digits) and denominator (lower digit). As such 14 / 35. The factors of numerator 14 = 2 x 7 The factors if denominator 35 = 5 x 7 Calculate the HCF of both numerator and.
fractions worksheet reduce to lowest terms worksheets simplifying pdf 6th grade.. collection of free printable math worksheets reducing fractions simplifying worksheet pdf with answers improper,simplifying fractions worksheets pdf reduce to lowest terms 5 worksheet grade 3,reducing improper fractions worksheet pdf kindergarten grade simplifying 5th worksheets,simplifying fractions … 18/07/2012 · Reducing a Fraction to Lowest Terms. Here I look at reducing a fraction to lowest terms. I do not take the shortest route, but show how I often perform the simplification if no one is watching!
22/10/2009 · How to find the lowest terms of fractions. Examples include one step division by common factor. how to cancel down larger fractions in multiple steps, and how to use the prime factors of the fractions worksheet reduce to lowest terms worksheets simplifying pdf 6th grade.. collection of free printable math worksheets reducing fractions simplifying worksheet pdf with answers improper,simplifying fractions worksheets pdf reduce to lowest terms 5 worksheet grade 3,reducing improper fractions worksheet pdf kindergarten grade simplifying 5th worksheets,simplifying fractions …
22/10/2009В В· How to find the lowest terms of fractions. Examples include one step division by common factor. how to cancel down larger fractions in multiple steps, and how to use the prime factors of the To reduce any fraction, we have to determine factors of its numerator (upper digits) and denominator (lower digit). As such 14 / 35. The factors of numerator 14 = 2 x 7 The factors if denominator 35 = 5 x 7 Calculate the HCF of both numerator and
29/03/2014 · One of the basic reasons why we reduce fraction to lowest terms is to lessen the burden of calculating large numbers. Of course, we would rather add or multiply and than and .So you see, the effort of multiplying the same fraction is lessen when they are reduced to lowest terms. 19/01/2011 · How to Reduce Fractions. Math is hard. It's easy to forget even core concepts when you are trying to remember dozens of different principles and methods. Here's your refresher on two methods to reduce fractions. List the …
The numerator and denominator have no common factors, so the fraction is already in lowest terms. Practice questions. Increase the terms of the fraction 2/3 so that the denominator is 18. Increase the terms of 4/9, changing the denominator to 54. Reduce the fraction 12/60 to … 18/07/2012 · Reducing a Fraction to Lowest Terms. Here I look at reducing a fraction to lowest terms. I do not take the shortest route, but show how I often perform the simplification if no one is watching!
The numerator and denominator have no common factors, so the fraction is already in lowest terms. Practice questions. Increase the terms of the fraction 2/3 so that the denominator is 18. Increase the terms of 4/9, changing the denominator to 54. Reduce the fraction 12/60 to … 05/11/2015 · To reduce a fraction to lowest terms, try to find the largest number that divides into both numerator and denominator. This number is also known as the greatest common divisor, or …
30/01/1998 · Reducing Fractions with Large Numbers Date: 01/30/98 at 09:37:30 From: Pat Subject: Reducing fractions Dear Dr. Math, A neighborhood child asked for help with a math problem involving reducing fractions. 20904/12 = 1742, so, reduced to lowest terms, 20904/52740 = 1742/4395. This always works, and always gives the largest common factor 19/01/2011 · How to Reduce Fractions. Math is hard. It's easy to forget even core concepts when you are trying to remember dozens of different principles and methods. Here's your refresher on two methods to reduce fractions. List the …
## How to Increase and Reduce the Terms of Fractions dummies
How to Increase and Reduce the Terms of Fractions dummies. 04/08/2010В В· Example: reduce to lowest terms the fraction 169187 / 177628. The method is called the Euclidean Algorithm. It finds the biggest number which divides into both the numerator and denominator. First you divide the bottom into the top. In this case it goes in 0 times with a remainder of 169187., 29/03/2014В В· One of the basic reasons why we reduce fraction to lowest terms is to lessen the burden of calculating large numbers. Of course, we would rather add or multiply and than and .So you see, the effort of multiplying the same fraction is lessen when they are reduced to lowest terms..
### Equivalent Fractions Finding the Lowest Terms - YouTube
Equivalent Fractions Finding the Lowest Terms - YouTube. 19/01/2011 · How to Reduce Fractions. Math is hard. It's easy to forget even core concepts when you are trying to remember dozens of different principles and methods. Here's your refresher on two methods to reduce fractions. List the …, fractions worksheet reduce to lowest terms worksheets simplifying pdf 6th grade.. collection of free printable math worksheets reducing fractions simplifying worksheet pdf with answers improper,simplifying fractions worksheets pdf reduce to lowest terms 5 worksheet grade 3,reducing improper fractions worksheet pdf kindergarten grade simplifying 5th worksheets,simplifying fractions ….
18/07/2012В В· Reducing a Fraction to Lowest Terms. Here I look at reducing a fraction to lowest terms. I do not take the shortest route, but show how I often perform the simplification if no one is watching! 24/04/2017В В· The directions of many worksheets, quizzes and tests will ask for fractions in their simplest form. To simplify a fraction, divide the top number, known as the numerator, and the bottom number, the denominator, by the greatest common factor.The GFC is the largest number that will divide into the numerator and denominator evenly.
By finding the LCM of the denominators, (called the lowest common denominator) you can convert unlike to like fractions and proceed with the adding or subtracting. Knowing the GCF helps reduce a You just studied 11 terms! Now up your study game with Learn mode.
04/08/2010 · Example: reduce to lowest terms the fraction 169187 / 177628. The method is called the Euclidean Algorithm. It finds the biggest number which divides into both the numerator and denominator. First you divide the bottom into the top. In this case it goes in 0 times with a remainder of 169187. fractions worksheet reduce to lowest terms worksheets simplifying pdf 6th grade.. collection of free printable math worksheets reducing fractions simplifying worksheet pdf with answers improper,simplifying fractions worksheets pdf reduce to lowest terms 5 worksheet grade 3,reducing improper fractions worksheet pdf kindergarten grade simplifying 5th worksheets,simplifying fractions …
The numerator and denominator have no common factors, so the fraction is already in lowest terms. Practice questions. Increase the terms of the fraction 2/3 so that the denominator is 18. Increase the terms of 4/9, changing the denominator to 54. Reduce the fraction 12/60 to … 19/01/2011 · How to Reduce Fractions. Math is hard. It's easy to forget even core concepts when you are trying to remember dozens of different principles and methods. Here's your refresher on two methods to reduce fractions. List the …
05/05/2006В В· Reducing fractions to lowest terms. Hi and I can automatically calculate for very large unusual fractions I sometimes encounter, such as "what is 489/7896 th's of the transferor's 6784/762543 th share of the land, and what is the fraction of the whole of the land that the transferor keeps?", and so forth. if you want the numerator and 12/10/2011В В· How To Reduce Fractions To Lowest Terms-Step By Step Math Lesson - Duration: This tutorial demonstrates how to reduce a fraction to lowest terms by using multiplication and cancellation
To reduce any fraction, we have to determine factors of its numerator (upper digits) and denominator (lower digit). As such 14 / 35. The factors of numerator 14 = 2 x 7 The factors if denominator 35 = 5 x 7 Calculate the HCF of both numerator and 18/07/2012В В· Reducing a Fraction to Lowest Terms. Here I look at reducing a fraction to lowest terms. I do not take the shortest route, but show how I often perform the simplification if no one is watching!
Regardless of which manual method you choose, using them to reduce fractions can be extremely tedious and time-consuming. Therefore I would suggest you bookmark the fraction reducer calculator and use it any time you are working with fractions. How to Convert Improper Fraction to Mixed Number 12/10/2011В В· How To Reduce Fractions To Lowest Terms-Step By Step Math Lesson - Duration: This tutorial demonstrates how to reduce a fraction to lowest terms by using multiplication and cancellation
Reduce the Fractions to its Lowest Terms Review: S1 . Title: Microsoft Word - reduce-1 Author: educurve 13 Created Date: 4/4/2017 3:21:06 PM 05/05/2006В В· Reducing fractions to lowest terms. Hi and I can automatically calculate for very large unusual fractions I sometimes encounter, such as "what is 489/7896 th's of the transferor's 6784/762543 th share of the land, and what is the fraction of the whole of the land that the transferor keeps?", and so forth. if you want the numerator and
04/08/2010 · Example: reduce to lowest terms the fraction 169187 / 177628. The method is called the Euclidean Algorithm. It finds the biggest number which divides into both the numerator and denominator. First you divide the bottom into the top. In this case it goes in 0 times with a remainder of 169187. 05/11/2015 · To reduce a fraction to lowest terms, try to find the largest number that divides into both numerator and denominator. This number is also known as the greatest common divisor, or …
Regardless of which manual method you choose, using them to reduce fractions can be extremely tedious and time-consuming. Therefore I would suggest you bookmark the fraction reducer calculator and use it any time you are working with fractions. How to Convert Improper Fraction to Mixed Number Reduce the Fractions to its Lowest Terms Review: S1 . Title: Microsoft Word - reduce-1 Author: educurve 13 Created Date: 4/4/2017 3:21:06 PM
24/04/2017В В· The directions of many worksheets, quizzes and tests will ask for fractions in their simplest form. To simplify a fraction, divide the top number, known as the numerator, and the bottom number, the denominator, by the greatest common factor.The GFC is the largest number that will divide into the numerator and denominator evenly. 30/01/2013В В· Some fractions have HUGE numerators and denominators. Here's a way to break it down into smaller, more managable reducing steps.
17/06/2010В В· An important part of fraction learning is understanding how to reduce a fraction to its lowest terms. When a fraction is in lowest terms, the numerator and denominator don't share any common factors. Help your fourth grader wrap his head around reducing fractions with this helpful worksheet. Need more help? Try Reducing to Lowest Terms #2. You just studied 11 terms! Now up your study game with Learn mode.
30/01/2013 · Some fractions have HUGE numerators and denominators. Here's a way to break it down into smaller, more managable reducing steps. 23/05/2017 · I suppose you’re asking about converting a ordinary positive fraction like $\frac{49}{91}$ to lowest terms, in this case $\frac7{13}$. If the numerator and denominator are small numbers, as in $\frac{10}{12}$, you
17/06/2010 · An important part of fraction learning is understanding how to reduce a fraction to its lowest terms. When a fraction is in lowest terms, the numerator and denominator don't share any common factors. Help your fourth grader wrap his head around reducing fractions with this helpful worksheet. Need more help? Try Reducing to Lowest Terms #2. fractions worksheet reduce to lowest terms worksheets simplifying pdf 6th grade.. collection of free printable math worksheets reducing fractions simplifying worksheet pdf with answers improper,simplifying fractions worksheets pdf reduce to lowest terms 5 worksheet grade 3,reducing improper fractions worksheet pdf kindergarten grade simplifying 5th worksheets,simplifying fractions …
### Reduce the Fractions to its Lowest Terms Review S1
How to reduce the fraction 14⁄35 to its lowest terms Quora. The numerator and denominator have no common factors, so the fraction is already in lowest terms. Practice questions. Increase the terms of the fraction 2/3 so that the denominator is 18. Increase the terms of 4/9, changing the denominator to 54. Reduce the fraction 12/60 to …, fractions worksheet reduce to lowest terms worksheets simplifying pdf 6th grade.. collection of free printable math worksheets reducing fractions simplifying worksheet pdf with answers improper,simplifying fractions worksheets pdf reduce to lowest terms 5 worksheet grade 3,reducing improper fractions worksheet pdf kindergarten grade simplifying 5th worksheets,simplifying fractions ….
### How to reduce the fraction 14вЃ„35 to its lowest terms Quora
What are some ways to reduce large fractions? Quora. 30/01/1998В В· Reducing Fractions with Large Numbers Date: 01/30/98 at 09:37:30 From: Pat Subject: Reducing fractions Dear Dr. Math, A neighborhood child asked for help with a math problem involving reducing fractions. 20904/12 = 1742, so, reduced to lowest terms, 20904/52740 = 1742/4395. This always works, and always gives the largest common factor 18/07/2012В В· Reducing a Fraction to Lowest Terms. Here I look at reducing a fraction to lowest terms. I do not take the shortest route, but show how I often perform the simplification if no one is watching!.
04/08/2010В В· Example: reduce to lowest terms the fraction 169187 / 177628. The method is called the Euclidean Algorithm. It finds the biggest number which divides into both the numerator and denominator. First you divide the bottom into the top. In this case it goes in 0 times with a remainder of 169187. 02/09/2019В В· There is an algorithm based on an identity accredited to Euclid. Thus, in computer programming it is called the Euclidean algorithm. Euclidean algorithm - Wikipedia Start by noting the numerator and denominator for later. Take note of which is lar...
12/10/2011В В· How To Reduce Fractions To Lowest Terms-Step By Step Math Lesson - Duration: This tutorial demonstrates how to reduce a fraction to lowest terms by using multiplication and cancellation 12/10/2011В В· How To Reduce Fractions To Lowest Terms-Step By Step Math Lesson - Duration: This tutorial demonstrates how to reduce a fraction to lowest terms by using multiplication and cancellation
06/01/2009В В· Reduce fractions to lowest terms using prime numbers.? Help with C++ Reduce fractions to their lowest terms? How do u reduce fractions to lowest terms? More questions. Easier way to reduce to lower terms - fractions that have a big number? How do I reduce large fractions to lowest terms? Answer Questions. To reduce any fraction, we have to determine factors of its numerator (upper digits) and denominator (lower digit). As such 14 / 35. The factors of numerator 14 = 2 x 7 The factors if denominator 35 = 5 x 7 Calculate the HCF of both numerator and
By finding the LCM of the denominators, (called the lowest common denominator) you can convert unlike to like fractions and proceed with the adding or subtracting. Knowing the GCF helps reduce a 22/10/2009В В· How to find the lowest terms of fractions. Examples include one step division by common factor. how to cancel down larger fractions in multiple steps, and how to use the prime factors of the
29/03/2014 · One of the basic reasons why we reduce fraction to lowest terms is to lessen the burden of calculating large numbers. Of course, we would rather add or multiply and than and .So you see, the effort of multiplying the same fraction is lessen when they are reduced to lowest terms. fractions worksheet reduce to lowest terms worksheets simplifying pdf 6th grade.. collection of free printable math worksheets reducing fractions simplifying worksheet pdf with answers improper,simplifying fractions worksheets pdf reduce to lowest terms 5 worksheet grade 3,reducing improper fractions worksheet pdf kindergarten grade simplifying 5th worksheets,simplifying fractions …
To reduce any fraction, we have to determine factors of its numerator (upper digits) and denominator (lower digit). As such 14 / 35. The factors of numerator 14 = 2 x 7 The factors if denominator 35 = 5 x 7 Calculate the HCF of both numerator and 06/01/2009В В· Reduce fractions to lowest terms using prime numbers.? Help with C++ Reduce fractions to their lowest terms? How do u reduce fractions to lowest terms? More questions. Easier way to reduce to lower terms - fractions that have a big number? How do I reduce large fractions to lowest terms? Answer Questions.
29/03/2014В В· One of the basic reasons why we reduce fraction to lowest terms is to lessen the burden of calculating large numbers. Of course, we would rather add or multiply and than and .So you see, the effort of multiplying the same fraction is lessen when they are reduced to lowest terms. We reduce a fraction to lowest terms by finding an equivalent fraction in which the numerator and denominator are as small as possible. This means that there is no number, except 1, that can be divided evenly into both the numerator and the denominator. To reduce a В· Reducing fractions
The numerator and denominator have no common factors, so the fraction is already in lowest terms. Practice questions. Increase the terms of the fraction 2/3 so that the denominator is 18. Increase the terms of 4/9, changing the denominator to 54. Reduce the fraction 12/60 to … 24/04/2017 · The directions of many worksheets, quizzes and tests will ask for fractions in their simplest form. To simplify a fraction, divide the top number, known as the numerator, and the bottom number, the denominator, by the greatest common factor.The GFC is the largest number that will divide into the numerator and denominator evenly.
Reduce the Fractions to its Lowest Terms Review: S1 . Title: Microsoft Word - reduce-1 Author: educurve 13 Created Date: 4/4/2017 3:21:06 PM 24/04/2017В В· The directions of many worksheets, quizzes and tests will ask for fractions in their simplest form. To simplify a fraction, divide the top number, known as the numerator, and the bottom number, the denominator, by the greatest common factor.The GFC is the largest number that will divide into the numerator and denominator evenly.
05/11/2015 · To reduce a fraction to lowest terms, try to find the largest number that divides into both numerator and denominator. This number is also known as the greatest common divisor, or … 04/08/2010 · Example: reduce to lowest terms the fraction 169187 / 177628. The method is called the Euclidean Algorithm. It finds the biggest number which divides into both the numerator and denominator. First you divide the bottom into the top. In this case it goes in 0 times with a remainder of 169187.
06/01/2009 · Reduce fractions to lowest terms using prime numbers.? Help with C++ Reduce fractions to their lowest terms? How do u reduce fractions to lowest terms? More questions. Easier way to reduce to lower terms - fractions that have a big number? How do I reduce large fractions to lowest terms? Answer Questions. fractions worksheet reduce to lowest terms worksheets simplifying pdf 6th grade.. collection of free printable math worksheets reducing fractions simplifying worksheet pdf with answers improper,simplifying fractions worksheets pdf reduce to lowest terms 5 worksheet grade 3,reducing improper fractions worksheet pdf kindergarten grade simplifying 5th worksheets,simplifying fractions …
19/01/2011 · How to Reduce Fractions. Math is hard. It's easy to forget even core concepts when you are trying to remember dozens of different principles and methods. Here's your refresher on two methods to reduce fractions. List the … 22/10/2009 · How to find the lowest terms of fractions. Examples include one step division by common factor. how to cancel down larger fractions in multiple steps, and how to use the prime factors of the
By finding the LCM of the denominators, (called the lowest common denominator) you can convert unlike to like fractions and proceed with the adding or subtracting. Knowing the GCF helps reduce a 12/10/2011В В· How To Reduce Fractions To Lowest Terms-Step By Step Math Lesson - Duration: This tutorial demonstrates how to reduce a fraction to lowest terms by using multiplication and cancellation
187126
|
{"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": 0, "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": 0.9623177647590637, "perplexity": 1064.4775376112025}, "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-2020-29/segments/1593655906934.51/warc/CC-MAIN-20200710082212-20200710112212-00081.warc.gz"}
|
https://plainmath.net/26026/supplement-given-patients-pressure-pressure-before-supplement-recorded
|
# A supplement was given to patients to lower their blood pressure. The blood pressure before and after the supplement was recorded.
A supplement was given to patients to lower their blood pressure. The blood pressure before and after the supplement was recorded.
What kind of variables are Begin and End and what kind of scale are they following? Multiple choice. Choose one answer for scale and one answer for variables.
Note: the scale is identified as either nominal, ordinal, interval, or ratio (Choose the correct answer). Please explain why you chose the answer.
Variables are defined as either numerical (count/discrete or decimals) OR categorical (ordinal or nominal) (Choose the correct answer). Please explain why you chose the answer.
You can still ask an expert for help
• Questions are typically answered in as fast as 30 minutes
Solve your problem for the price of one coffee
• Math expert for every subject
• Pay only if we can solve it
pierretteA
Step 1
We know that the blood pressure readings are made up with two values.
Systolic Blood pressure
Diastolic Blood pressure
The blood pressure readings are measured in millimeters of mercury (mmHg) and that the values are always in pairs. The scale of the pressure meter ranges from 0 to 300 (mmHg).
step 2
Now the blood pressure of a patient was recorded before and after the supplement.
From the information in Step 1 we can clearly say that the blood pressure is a type of continuous data. Hence, Begin and End are numerical(decimals) variables.
The pressure meter ranges from 0 to 300 (mmHg) which implies that the scale has true zero point. Hence the kind of scale are they following is a ratio scale.
|
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 24, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "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": 0.6751090288162231, "perplexity": 1122.4400518852262}, "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-2022-49/segments/1669446710933.89/warc/CC-MAIN-20221203143925-20221203173925-00302.warc.gz"}
|
http://www.ck12.org/physics/Average-Velocity/lesson/user:a3Jvc2VuYXVAcGVyaGFtLmsxMi5tbi51cw../Average-Velocity/r1/
|
<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
# Average Velocity
## Displacement divided by time.
Estimated26 minsto complete
%
Progress
Practice Average Velocity
Progress
Estimated26 minsto complete
%
Average Velocity
You will learn the meaning of speed, velocity and average velocity.
### Key Equations
Speed = distance/time
Average Velocity
Guidance
Speed is the distance traveled divided by the time it took to travel that distance. Velocity is the instantaneous speed and direction. Average velocity is the displacement divided by the time.
#### Example 1
Pacific loggerhead sea turtles migrate over 7,500 miles (12,000 km) between nesting beaches in Japan and feeding grounds off the coast of Mexico. If the average speed of a loggerhead is about 45 km/day, how long does it take for it to complete the distance of a one-way migration?
Question: [days]
Given:
Equation: therefore
Plug n’ Chug:
### Time for Practice
1. Two cars are heading right towards each other, but are 12 km apart. One car is going 70 km/hr and the other is going 50 km/hr. How much time do they have before they collide head on?
2. You drive the 10 miles to work at an average speed of 40 mph. On the way home you hit severe traffic and drive at an average speed of 10 mph. What is your average speed for the trip?
1. 0.1 hours = 6 minutes
2. 16 mph
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9243046641349792, "perplexity": 2072.3372683914217}, "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-2016-22/segments/1464049276567.28/warc/CC-MAIN-20160524002116-00206-ip-10-185-217-139.ec2.internal.warc.gz"}
|
https://www.ajas.info/journal/view.php?viewtype=pubreader&number=24283
|
# Impact of Ecklonia stolonifera extract on in vitro ruminal fermentation characteristics, methanogenesis, and microbial populations
## Article information
Asian-Australas J Anim Sci.. 2019;32(12):1864-1872
Publication date (electronic) : 2019 May 28
doi : https://doi.org/10.5713/ajas.19.0092
1Institute of Agriculture and Life Science and University-Centered Labs, Gyeongsang National University, Jinju 52828, Korea
2Division of Applied Life Science (BK21Plus) and Institute of Agriculture and Life Science (IALS), Gyeongsang National University, Jinju 52828, Korea
3Livestock Experiment Station, Gyeongsangnamdo Livestock Promotion Research Institute, Sancheong 52733, Korea
4Institute of Agriculture and Life Science, Gyeongsang National University, Jinju 52828, Korea
5Division of Applied Life Science (BK21Plus), Gyeongsang National University, Jinju 52828, Korea
a
These authors contributed equally to the work.
*Corresponding Author: Sung Sill Lee, Tel: +82-55-772-1883, Fax: +82-55-772-1889, E-mail: [email protected]
Received 2019 February 1; Revised 2019 April 8; Accepted 2019 May 16.
## Abstract
### Objective
This study was conducted to evaluate the effects of Ecklonia stolonifera (E. stolonifera) extract addition on in vitro ruminal fermentation characteristics, methanogenesis and microbial populations.
### Methods
One cannulated Holstein cow (450±30 kg) consuming timothy hay and a commercial concentrate (60:40, w/w) twice daily (09:00 and 17:00) at 2% of body weight with free access to water and mineral block were used as rumen fluid donors. In vitro fermentation experiment, with timothy hay as substrate, was conducted for up to 72 h, with E. stolonifera extract added to achieve final concentration 1%, 3%, and 5% on timothy hay basis.
### Results
Administration of E. stolonifera extract to a ruminant fluid-artificial saliva mixture in vitro increased the total gas production. Unexpectedly, E. stolonifera extracts appeared to increase both methane emissions and hydrogen production, which is contrasts with previous observations with brown algae extracts used under in vitro fermentation conditions. Interestingly, real-time polymerase chain reaction indicated that as compared with the untreated control the ciliate-associated methanogen and Fibrobacter succinogenes populations decreased, whereas the Ruminococcus flavefaciens population increased as a result of E. stolonifera extract supplementation.
### Conclusion
E. stolonifera showed no detrimental effect on rumen fermentation characteristics and microbial population. Through these results E. stolonifera has potential as a viable feed supplement to ruminants.
## INTRODUCTION
Macro-algae are economically important and an under exploited plant resources, providing integral biomass for human foods and animal feed in recent years. Macro-algae-derived compounds have a broad range of biological activities such as antibiotic, antiviral, antioxidant, antifouling, anti-inflammatory, cytotoxic, anti-adipogenic, and antimitotic and thus confer potential health benefits [1]. In addition, macro-algae-derived compounds have been shown to increase growth rates and feed efficiency in ruminants [2]. However, they have counter-intuitively also been shown to impair fiber digestibility; thereby limiting diet digestibility [3].
Phaeophyta or brown algae are predominantly greenish brown in color due to the presence of the carotenoid fucoxanthin, and contain primary polysaccharides such as alginates, laminarins, fucans, and cellulose [4]. Ecklonia stolonifera (E. stolonifera) is a brown algae belonging to the Laminariaceae family that is commonly found in the sea forests off the coasts of Korea and Japan, growing on rocks near and below the low-tide mark on rough open coasts [5]. E. stolonifera has traditionally been utilized as an edible product and contains high levels of diverse phlorotannins, which are polymers of phloroglucinol found only in brown algae that have diverse biological activities, including anti-oxidative, antibacterial [5], and anti-inflammatory [6] properties. Moreover, E. stolonifera contains polyphenolic compounds that have been suggested to deter the grazing and growth of the seaweed’s predators [7]. However, a few studies reported that algae have potential effect on rumen fermentation characteristics and methane reduction [8,9]. Identification of feed additives that can modify the rumen microbial system to manipulate ruminal fermentation characteristics and increase the efficiency of feed utilization is an effective strategy for inhibiting ruminal methanogenesis for reducing methane emissions without an adverse effect on rumen function.
To this end, we evaluated the potential effect of E. stolonifera on rumen fermentation using in vitro gas production technique. It has previously been applied to study the fermentation kinetics of feed composition. In addition, it can allow for the rapid screening of a large number of feed additives that may have effects on gas production [10].
Therefore, this study was conducted to evaluate effects of E. stolonifera extracts on in vitro ruminal fermentation, gas profile, and changes in microbial populations. These results could help to promote E. stolonifera as a natural alternative for improving ruminal fermentation.
## MATERIALS AND METHODS
All experimental protocols were approved by the Animal Care and Use Committee of Gyeongsang National University (GNU-180130-A0007, Jinju, Gyeongsangnam-do, Korea).
### Ecklonia stolonifera extract preparation
E. stolonifera extract was obtained from the Jeju Biodiversity Research Institute (JBRI, Jeju, Korea). In brief, the plant material was washed and cut into small pieces, freeze-dried, and crushed. The plant powder was extracted with 80% methanol at room temperature (20°C) using an ultrasonic cleaner (Branson Ultrasonics Corporation, Danbury, CT, USA). After extraction, the methanol eluate solutions were filtered through Whatman No. 1 filter (Whatman International Ltd, Maidstone, UK) paper and concentrated under a vacuum.
### In vitro fermentation design
One cannulated Holstein cow (450±30 kg) was used as rumen fluid donors and provided with ad libitum access to a mineral-vitamin block and water. Twice daily (09:00 and 17:00), cows were fed 2% of their body weight in timothy hay and commercial concentrate at a 60:40 (w/w) ratio. Rumen fluid was collected before morning feedings and filtered through four layers of cheesecloth. Next, it was diluted with artificial saliva and stored at 39°C.
The chemical composition (% dry matter [DM] basis) of commercial timothy hay was as follows: moisture content, 8.87%; crude protein, 13.37%; ether extracts, 2.25%; crude fiber, 21.87%; crude ash, 8.62%; neutral detergent fiber, 53.18%; and acid detergent fiber, 30.57%.
The rumen fluid was mixed with McDougall’s buffer in a 1:2 ratio. Next, 15 mL of the mixture was dispensed anaerobically into 50-mL serum bottles containing 0.3 g of timothy for CON and E. stolonifera extract for treatments (TRTs) (3 mg for TRT1, 9 mg for TRT2, 15 mg for TRT3). The serum bottles were sealed anaerobically with an aluminum-capped butyl rubber stopper in pure N2 gas, and incubated in a shaking incubator (Jeio Tech, SI-900R, Daejeon, Korea; 120×rpm) at 39°C for 72 h. The in vitro fermentation experiment was a completely randomized block design and performed in triplicate, using 60 serum bottles (4 treatments × 5 incubation times × 3 replicates times).
### Determination of gas profiles and ruminal fermentation characteristics
Total gas production in the samples was measured with head space gas chromatography using a detachable pressure transducer and a digital readout voltmeter (Laurel Electronics, Inc., Costa Mesa, CA, USA). The transducer was connected to the inlet of a disposable Luer-lock three-way stopcock. Gas pressure in the headspace above the culture medium was read from the light emitting diode display unit after inserting a hypodermic syringe needle. Methane and carbon dioxide content was measured using a TCD detector with a Carboxen-1006 Plot capillary column (30 mm×0.53 mm, Supelco, Bellefonte, PA, USA), after connecting another stopcock outlet to a gas chromatograph (HP 5890, Agilent Technologies, Santa Clara, CA, USA).
Next, serum bottles were uncapped, and the culture medium was subsampled for pH (MP230, Mettler-Toledo, Columbus, OH, USA), ammonia-N and volatile fatty acid (VFA) analyses. Ammonia-N concentration was measured as optical density (OD) values at 630 nm using a UV/VIS spectrophotometer (Model 680, Bio-Rad laboratories, Hercules, CA, USA). For VFA measurements, sub-samples were centrifuged at 3,000× rpm for 3 min. The resultant supernatant was filtered using a 0.2 μm disposable syringe filter (Whatman Inc., Clifton, NJ, USA) high performance liquid chromatography (Agilent-1200, Waldbronn, Germany) using a UV/VIS detector with a MetaCarb 87H column (300 mm×7.8 mm, Varian, Palo Alto, CA, USA).
In vitro DM disappearance rate was determined following a modified Ørskov’s method, using nylon-bag digestion. After incubation, the nylon bag containing serum bottles was washed twice in a water-bath equipped with a Heidolph Rotamax 120 (Heidolph Instruments, Nuremberg, Germany) at 100×rpm for 30 min and then oven dried at 60°C to a constant weight. The DM disappearance was the difference in serum-bottle weight before and after incubation.
### Microbial growth rate
At the end of each fermentation period, samples were centrifuged at 3,000×rpm for 3 min to remove feed particles. The supernatant was then re-centrifuged at 14,000×rpm for 3 min to obtain a final supernatant for protein and glucose analysis. Some of the supernatant was dyed with Coomassie Blue G-250 for spectrophotometrically measuring protein content as OD at 595 nm (Model 680, Bio-Rad Laboratories, USA) [11]. For measuring glucose, 200 μL of supernatant was mixed with 600 μL of DNS solution and incubated for 5 min in a boiling water bath. Glucose concentration was the OD at 595 nm, determined with a microplate reader (Model 680, Bio-Rad Laboratories, USA) [12]. Pellets from the centrifugation were washed with sodium phosphate buffer (pH 6.5) four more times and then subjected to OD measurements at 550 nm (Model 680, Bio-Rad Laboratories, USA) to evaluate microorganism growth rates.
### Quantitative polymerase chain reaction
DNA was extracted from the incubated rumen samples using a QIAamp mini kit (QIAGEN, Valencia, CA, USA) according to the modified bead-beating protocol. Total nucleic acids were extracted by a high speed reciprocal shaker (TissueLyser; QIAGEN, USA), which retains the samples in screw-capped tubes containing ceramic and silica beads. In brief, 1 mL aliquots were taken from 15 mL of the incubated culture solution and centrifuged at 3,000 rpm for 5 min; 1 μL of the supernatant was used for nucleic acid concentration determination using a NanoDrop spectrophotometer (Thermo Scientific, Wilmington, DE, USA).
The polymerase chain reaction (PCR) primer sets were selected for amplification of general bacteria [13], ciliate-associated methanogens [14], methanogenic archaea [15], Fibrobacter succinogenes (F. succinogenes) [16], Ruminococcus albus (R. albus) [16], and Ruminococcus flavefaciens (R. flavefaciens) [16] as reported previously (Table 1).
Polymerase chain reaction primer sets for real-time polymerase chain reaction assays
Quantitative real-time PCR assays (CFX96 Real-Time system; Bio-Rad, USA) were conducted using the SYBR Green Supermix (QPK-201, Toyobo Co., Ltd., Tokyo, Japan) according to the methods described by Denman and McSweeney [13] and Denman et al [17]. The relative abundance of microbes was expressed according to the cycle threshold (Ct) difference as: 2ΔCt (target) − ΔCt (control). All quantitative PCR mixtures consisted of a 20 μL volume, containing forward and reverse primers, DNA template, and DNA dye SYBR Green Supermix. The PCR amplification conditions for the target DNA, including the primer annealing and extension temperatures, were the same as those reported in the corresponding reference for each primer (Table 1).
### Statistical analysis
All experimental data were analyzed using the general linear model procedure of SAS [18] as a completely randomized block design. The effects of supplementation of E. stolonifera extract on pH, total gas production, DM disappearance, gas profiles, VFA profiles, and methanogen diversity were compared to those of the CON group, and the data were subjected to polynomial regression to measure the linear and quadratic effects of increasing concentrations of E. stolonifera. Variability in the data is expressed as the standard error of the mean; p<0.05 was considered to be statistically significant, whereas p<0.10 was considered to indicate a tendency.
## RESULTS
### In vitro fermentation characteristics
E. stolonifera extract demonstrated improved cumulative gas production by mixed ruminal microorganisms as compared to that of the CON group (Table 2). However, there was no effect of E. stolonifera at different concentrations on pH and DM disappearance as compared with those of the CON group, except for an effect on DM disappearance at 24 h detected in the quadratic model.
Effect of Ecklonia stolonifera extracts on rumen fermentation characteristics
As shown in Table 3, supplementation of E. stolonifera extract reduced the total levels of VFAs at 3 h and 48 h, acetate at 48 h, and butyrate at 3 h. Overall, supplementation of E. stolonifera extract decreased the acetic acid-to propionic acid ratio (A/P ratio) at 48 h as compared with that of the CON group.
Effect of Ecklonia stolonifera extracts on VFA by mixed rumen microbial fermentation
Lastly, supplementation of E. stolonifera extract increased the methane emissions at 3 h and 12 h (linear models only); hydrogen production at 3 h, 12 h, and 72 h; and ammonia production at 72 h. By contrast, ammonia production was reduced at 24 h, respectively, as compared to those of the CON group (Table 4).
Effect of Ecklonia stolonifera extracts on in vitro gas and ammonia production by mixed rumen fermentation
### Change in ruminal microbial diversity
E. stolonifera extract increased the microbial growth rate at 48 h and the glucose concentration at 3 h, while reducing the protein concentration at 12 h and at 24 h as compared with those of the CON group (Table 5).
Effect of Ecklonia stolonifera extracts on rumen microbial growth rate, protein and glucose concentration
The ciliate-associated methanogen and methanogenic archaea populations were reduced at 12 h (p<0.0001) and 24 h (p = 0.0164) following supplementation with various concentrations of E. stolonifera extract as compared with those of the CON group. In addition, E. stolonifera extract reduced the abundance of the major fibrolytic microorganisms such as F. succinogenes at 12 h (p = 0.0113) and 24 h (p = 0.0145). The proportion of R. flavefaciens increased at 12 h of incubation with E. stolonifera extract (p = 0.0001), whereas the R. albus population remained unchanged or slightly increased as compared with that of the CON group (Figure 1).
Relative quantification of rumen microorganism populations under in vitro ruminal fermentation for (a) 12 h and (b) 24 h. Dietary treatments were as follows: CON, basal diet (without Ecklonia stolonifera extract); TRT 1, 1% Ecklonia stolonifera; TRT 2, 3% Ecklonia stolonifera; TRT 3, 5% Ecklonia stolonifera, on a substrate (timothy hay) basis. a,b Means with different superscripts in the same row indicate significant differences (p<0.05).
## DISCUSSION
Denis et al [19] reported that algae contain candidate compounds with potential to assist in ruminants feeding for improved gas production and fermentation management, within the context of dietary fiber provision. In this study, dietary fiber, as determined through the dose response of E. stolonifera, induced an increase in total gas production without any accompanying change in DM loss. DM disappearance only showed an effect with the addition of 1%, 3%, and 5% E. stolonifera extract at 24 h incubation, whereas the total gas production under all levels of E. stolonifera extract was higher as compared to that under incubation with Timothy hay alone at 24, 48, and 72 h, indicating the potential of this extract for improved feed efficiency [20]. The pH also remained consistent in the range of 6.49 to 7.48 for all doses of E. stolonifera applied during microbial fermentation, suggesting that ruminal microbial activity was not negatively affected since it was greater than the minimal pH of 5.0 to 5.5 [21].
By contrast, Wang et al [3] and Dubois et al [20] reported that brown algae species resulted in lower gas production than that of the control sample during in vitro ruminal fermentation. Therefore, some bioactive compounds of certain brown algae species might reduce the utilization of nutrients, thereby directly inhibiting microbial activity or indirectly by forming complexes with the nutrients [22]. Interestingly, the E. stolonifera extract caused a decrease in the total VFA and acetate concentrations, and resulted in a lower A/P ratio than those of the CON group at 48 h incubation, demonstrating that fermentation was affected. Secondary metabolites from E. stolonifera extracts have been reported to contain phlorotannins and polyphenolic compounds, which have strong antimicrobial properties and can deter the growth of the seaweed’s predators [7]. Thus, it is possible that these secondary metabolites may have induced a reduction in the total VFA concentration and altered the acetate and propionate concentrations, which are common characteristics often associated with anti-nutritional factors that interfere with ruminal fermentation [23].
With regards to emission gases, E. stolonifera extracts appeared to increase the in vitro methane emissions, and hydrogen and ammonia production, while carbon dioxide production did not increase under in vitro ruminal fermentation. As such, these results do not demonstrate a clear consensus trend, given that a mixed outcome was observed under different conditions. Rumen ammonia production may vary depending on the proportion of feed protein and the degradation rate; therefore, it was difficult to observe any difference in ammonia production except at 24 h and 72 h of fermentation, since timothy hay was the only substrate utilized. Wang et al [3] and Machado et al [23] reported a reduction of methane emissions when experimenting with brown algae extracts under in vitro fermentation conditions. Brown algae species generally show the ability to reduce methane emissions, which is most likely attributed to their phlorotannins and a range of other natural products [22,24]. However, the results from our study are in disagree with those of Wang et al [3] and Machado et al [23] as the E. stolonifera extracts appeared to actually increase methane emissions and hydrogen production at 3 h. This finding is in line with the results of Mitsumori and Sun [25], who suggested that ruminal methanogens utilizing mainly hydrogen would be the main source of an increase in methane emissions.
The effects of E. stolonifera on microbial diversity also initially appeared to be counter intuitive with the observed increase in methane and hydrogen production. E. stolonifera extracts reduced the populations of the ciliate-associated methanogens, methanogenic archaea, and F. succinogenes, while increasing the R. flavefaciens population as compared with those of the CON group. However, the R. albus population was left unchanged. Ciliate-associated methanogens may generate up to 37% of the methane produced in the rumen [26], and most methanogenic archaea can reduce CO2 with H2 to produce methane [27]. However, F. succinogenes is a non-H2-producing species [28]. Therefore, given the major reduction in the ciliate-associated methanogens and methanogenic archaea populations, a consequent reduction in methane production would be expected; however, this was not the case. R. albus and R. flavefaciens are two of the three major members of the fibrolytic microorganism population, the third being F. succinogenes. R. albus has shown great promise in the production of H2 from energy forage, with potential for utilizing cellulosic and hemicellulosic biomass [29]. In addition, R. flavefaciens normally produces succinic acid as a major fermentation product together with acetic and formic acids, H2, and CO2 [30]. As such, the increase in the R. flavefaciens population along with the unchanged R. albus population may have contributed to the observed increase in hydrogen production. Therefore, even with reductions in the ciliate-associated methanogens and methanogenic archaea populations, the increase in hydrogen availability may have allowed for increased methane emissions. Chaucheyras-Durand et al [28] showed that methane emissions clearly reduced when the dominant fibrolytic species was a non-H2-producing species such as F. succinogenes, without significantly impairing fiber degradation and fermentation in the rumen. This suggests that H2 is the critical factor for the microbial ecosystem in ruminants. The H2 produced during enteric fermentation is the precursor of methane emissions from ruminants, and thus the regulation of H2, rather than methane appears to be the key to controlling ruminant methane emissions.
Lastly, the E. stolonifera extract doses that led to higher microbial growth rates also caused higher total gas production as compared to the CON group; therefore, the rumen microorganism growth rate appears to be closely related to the total gas production and fermentation process, as suggested by Hungate [31]. In particular, the E. stolonifera extracts significantly increased microbial growth at 48 h as compared to that of the CON group. Moreover, our results confirmed that rumen fermentation with E. stolonifera extracts did not result in any negative side effects on protein or glucose concentrations throughout the experimental period. In fact, E. stolonifera extracts appeared to reduce the protein concentration at 12 h and 24 h. However, the protein concentration does not appear to be correlated with ammonia concentration, as Mehrez et al [32] reported that the optimal ammonia concentration could lead to maximal protein synthesis by microorganisms.
In conclusion, we demonstrated the effects of E. stolonifera on in vitro ruminant fermentation characteristics. E. stolonifera extracts also appear to be capable of mitigating a series of effects throughout the period of in vitro rumen fermentation, some of which may not be desirable. For example, E. stolonifera extracts could increase methane emissions and hydrogen production, which disagrees with previous observations on brown algae extracts under in vitro fermentation conditions. However, the changes in ruminal microbial diversity were able to partially explain the observed increase in methane and hydrogen observed with treatment of E. stolonifera extracts. More research is required to elucidate the potential of E. stolonifera for improving growth performance and methane emissions of ruminants.
## Notes
CONFLICT OF INTEREST
We certify that there is no conflict of interest with any financial organization regarding the material discussed in the manuscript.
## ACKNOWLEDGMENTS
This work was supported by the National Foundation of Korea Grant funded by the Korean Government (NRF-2015R1A 6A1A03031413). Jin Suk Jeong was supported by Postdoctoral Fellowship from the BK21Plus Program, the Ministry of Education, Science and Technology, Republic of Korea. This work was presented as a part of a doctoral dissertation by Nyeon Hak Shin.
## References
1. Jung HA, Jung HJ, Jeong HY, Kwon HJ, Ali MY, Choi JS. Phlorotannins isolated from the edible brown alga Ecklonia stolonifera exert anti-adipogenic activity on 3T3-L1 adipocytes by downregulating C/EBPα and PPARγ. Fitoterapia 2014;92:260–9. https://doi.org/10.1016/j.fitote.2013.12.003 .
2. Chowdhury S, Huque K, Khatun M. Algae in animal production. In : Agracultural Science of Biodiversity and Sustainability Workshop. Tune Landboskole, Denmark; 1995. p. 181–91.
3. Wang Y, Xu Z, Bach SJ, McAllister TA. Effects of phlorotannins from Ascophyllum nodosum (brown seaweed) on in vitro ruminal digestion of mixed forage or barley grain. Anim Feed Sci Technol 2008;145:375–95. https://doi.org/10.1016/j.anifeedsci.2007.03.013 .
4. Haugan JA, Liaaenjensen S. Algal Carotenoids 54. Carotenoids of brown algae (Phaeophyceae). Biochem Syst Ecol 1994;22:31–41. https://doi.org/10.1016/0305-1978(94)90112-0 .
5. Kuda T, Kunii T, Goto H, Suzuki T, Yano T. Varieties of antioxidant and antibacterial properties of Ecklonia stolonifera and Ecklonia kurome products harvested and processed in the Noto peninsula, Japan. Food Chem 2007;103:900–5. https://doi.org/10.1016/j.foodchem.2006.09.042 .
6. Kim S, Wijesekara I. Development and biological activities of marine-derived bioactive peptides: a review. J Funct Foods 2010;2:1–9. https://doi.org/10.1016/j.jff.2010.01.003 .
7. Winter FC, Estes JA. Experimental evidence for the effects of polyphenolic compounds from Dictyoneurum californicum Ruprecht (Phaeophyta: Laminariales) on feeding rate and growth in the red abalone Haliotus rufescens Swainson. J Exp Mar Biol Ecol 1992;155:263–77. https://doi.org/10.1016/0022-0981(92)90067-K .
8. Lee SJ, Shin NH, Jeong JS, Kim ET, Lee SK, Lee SS. Effect of Rhodophyta extracts on in vitro ruminal fermentation characteristics, methanogenesis and microbial populations. Asian-Australas J Anim Sci 2018;31:54–62. https://doi.org/10.5713/ajas.17.0620 .
9. Lee SJ, Shin NH, Jeong JS, et al. Effects of Gelidium amansii extracts on in vitro ruminal fermentation characteristics, methanogenesis, and microbial populations. Asian-Australas J Anim Sci 2018;31:71–9. https://doi.org/10.5713/ajas.17.0619 .
10. Pellikaan WF, Hendriks WH, Uwimana G, Bongers LJGM, Becker PM, Cone JW. A novel method to determine simultaneously methane production during in vitro gas production using fully automated equipment. Anim Feed Sci Technol 2011;168:196–205. https://doi.org/10.1016/j.anifeedsci.2011.04.096 .
11. Bradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 1976;72:248–54. https://doi.org/10.1016/0003-2697(76)90527-3 .
12. Miller GL. Use of dinitrosalicylic acid reagent for determination of reducing sugar. Anal Biochem 1959;31:426–8. https://doi.org/10.1021/ac60147a030 .
13. Denman SE, McSweeney CS. Development of a real-time PCR assay for monitoring anaerobic fungal and cellulolytic bacterial populations within the rumen. FEMS Microbiol Ecol 2006;58:572–82. https://doi.org/10.1111/j.1574-6941.2006.00190.x .
14. Luton PE, Wayne JM, Sharp RJ, Riley PW. The mcrA gene as an alternative to 16S rRNA in the phylogenetic analysis of methanogen populations in landfill. Microbiology 2002;148:3521–30. https://doi.org/10.1099/00221287-148-11-3521 .
15. Tajima K, Nagamine T, Matsui H, Nakamura M, Aminov RI. Phylogenetic analysis of archaeal 16S rRNA libraries from the rumen suggests the existence of a novel group of archaea not associated with known methanogens. FEMS Microbiol Lett 2001;200:67–72. https://doi.org/10.1111/j.1574-6968.2001.tb10694.x .
16. Koike S, Kobayashi Y. Development and use of competitive PCR assays for the rumen cellulolytic bacteria: Fibrobacter succinogenes, Ruminococcus albus and Ruminococcus flavefaciens . FEMS Microbiol Lett 2001;204:361–6. https://doi.org/10.1111/j.1574-6968.2001.tb10911.x .
17. Denman SE, Tomkins NW, McSweeney CS. Quantitation and diversity analysis of ruminal methanogenic populations in response to the antimethanogenic compound bromochloromethane. FEMS Microbiol Ecol 2007;62:313–22. https://doi.org/10.1111/j.1574-6941.2007.00394.x .
18. SAS Institute Inc. SAS/STAT user’s guide: Version 9.2 edn Cary, NC, USA: SAS Institute Inc; 2002.
19. Denis C, Morançais M, Li M, et al. Study of the chemical composition of edible red macroalgae Grateloupia turuturu from Brittany (France). Food Chem 2010;119:913–7. https://doi.org/10.1016/j.foodchem.2009.07.047 .
20. Dubois B, Tomkins NW, Kinley RD, et al. Effect of tropical algae as additives on rumen in vitro gas production and fermentation characteristics. Am J Plant Sci 2013;4:34–43. https://doi.org/10.4236/ajps.2013.412A2005 .
21. Hoover WH. Chemical factors involved in ruminal fiber digestion. J Dairy Sci 1986;69:2755–66. https://doi.org/10.3168/jds.S0022-0302(86)80724-X .
22. Min BR, Barry TN, Attwood GT, Mc-Nabb WC. The Effect of condensed tannins on the nutrition and health of ruminants fed fresh temperate forages: a review. Anim Feed Sci Technol 2003;106:3–19. https://doi.org/10.1016/S0377-8401(03)00041-5 .
23. Machado L, Magnusson M, Paul NA, de Nys R, Tomkins N. Effects of marine and freshwater macroalgae on in vitro total gas and methane production. PLoS One 2014;9:e85289. https://doi.org/10.1371/journal.pone.0085289 .
24. Gupta S, Abu-Ghannam N. Bioactive potential and possible health effects of edible brown seaweeds. Trends Food Sci Technol 2011;22:315–26. https://doi.org/10.1016/j.tifs.2011.03.011 .
25. Mitsumori M, Sun W. Control of rumen microbial fermentation for mitigating methane emissions from the rumen. Asian-Australas J Anim Sci 2008;21:144–54. https://doi.org/10.5713/ajas.2008.r01 .
26. Finlay BJ, Esteban G, Clarke KJ, et al. Some rumen ciliates have endosymbiotic methanogens. FEMS Microbiol Lett 1994;117:157–61.
27. Thauer RK, Kaster AK, Seedorf H, Buckel W, Hedderich R. Methanogenic archaea: ecologically relevant differences in energy conservation. Nat Rev Microbiol 2008;6:579–91. https://doi.org/10.1038/nrmicro1931 .
28. Chaucheyras-Durand F, Masséglia S, Fonty G, Forano E. Influence of the composition of the cellulolytic flora on the development of hydrogenotrophic microorganisms, hydrogen utilization, and methane production in the rumens of gnotobiotically reared lambs. Appl Environ Microbiol 2010;76:7931–7. https://doi.org/10.1128/AEM.01784-10 .
29. Ntaikou I, Gavala HN, Kornaros M, Lyberatos G. Hydrogen production from sugars and sweet sorghum biomass using Ruminococcus albus . Int J Hydrogen Energy 2008;33:1153–63. https://doi.org/10.1016/j.ijhydene.2007.10.053 .
30. Latham MJ, Wolin MJ. Fermentation of cellulose by Ruminococcus flavefaciens in the presence and absence of Methanobacterium ruminantium. Appl Environ Microbiol 1977;34:297–301.
31. Hungate RE. The rumen and it’s microbes NY, USA: Academic Press; 1966. p. 92–446.
32. Mehrez AZ, Ørskov ER, Mcdonald I. Rates of rumen fermentation in relation to ammonia concentration. Br J Nutr 1977;38:437–43. https://doi.org/10.1079/BJN19770108 .
## Article information Continued
### Figure 1
Relative quantification of rumen microorganism populations under in vitro ruminal fermentation for (a) 12 h and (b) 24 h. Dietary treatments were as follows: CON, basal diet (without Ecklonia stolonifera extract); TRT 1, 1% Ecklonia stolonifera; TRT 2, 3% Ecklonia stolonifera; TRT 3, 5% Ecklonia stolonifera, on a substrate (timothy hay) basis. a,b Means with different superscripts in the same row indicate significant differences (p<0.05).
### Table 1
Polymerase chain reaction primer sets for real-time polymerase chain reaction assays
Target species Primer sequences (5′ to 3′) Reference
General bacteria F: CGG CAA CGA GCG CAA CCC
R: CCA TTG TAG CAC GTG TGT AGC C
[13]
Ciliate-associated methanogens F: AGG AAT TGG CGG GGG AGC AC
R: TGT GTG CAA GGA GCA GGG AC
[14]
Methanogenic archaea F: GGT GGT GTM GGA TTC ACA CAR TAY GCW ACA GC
R: TTC ATT GCR TAG TTW GGR TAG TT
[15]
Fibrobacter succinogenes F: GGT ATG GGA TGA GCT TGC
R: GCC TGC CCC TGA ACT ATC
[16]
Ruminococcus albus F: CCC TAA AAG CAG TCT TAG TTC G
R: CCT CCT TGC GGT TAG AAC A
[16]
Ruminococcus flavefaciens F: TCT GGA AAC GGA TGG TA
F: TCT GGA AAC GGA TGG TA
[16]
### Table 2
Effect of Ecklonia stolonifera extracts on rumen fermentation characteristics
Incubation time (h) Treatments1) SEM Contrast
CON TRT1 TRT2 TRT3 Linear Quadratic
pH
3 7.48 7.43 7.48 7.46 0.04 0.9938 0.6867
12 7.32 7.25 7.33 7.28 0.03 0.8845 0.8023
24 6.89 6.90 6.91 6.87 0.02 0.7286 0.2639
48 6.63 6.67 6.64 6.59 0.03 0.3154 0.2283
72 6.55 6.49 6.50 6.50 0.03 0.3132 0.3039
Gas production (mL/g DM)
3 175.01 187.58 176.12 176.65 6.96 0.8386 0.4122
12 191.38 204.53 188.48 205.64 11.79 0.6261 0.8691
24 248.99b 252.53ab 250.31b 259.23a 2.31 0.0245 0.2764
48 282.89b 288.11b 289.38b 300.10a 3.04 0.0046 0.3933
72 288.85b 306.54a 314.04a 311.88a 3.21 0.0007 0.0148
DM disappearance (%)
3 17.48 17.94 16.94 16.44 0.59 0.1595 0.4458
12 17.83 19.03 20.07 20.34 1.96 0.3557 0.8163
24 31.72ab 29.14b 29.99ab 32.52a 0.97 0.4734 0.0299
48 37.71 38.87 38.13 39.28 0.62 0.1911 0.9992
72 41.34 41.99 41.55 41.62 0.37 0.8107 0.4616
SEM, standard error of the mean; DM, dry matter.
1)
Dietary treatments were as follows: CON, basal diet (without Ecklonia stolonifera extract); TRT 1, 1% Ecklonia stolonifera; TRT 2, 3% Ecklonia stolonifera; TRT 3, 5% Ecklonia stolonifera on a substrate (timothy hay) basis.
a,b
Means with different superscripts in the same row indicate significant differences (p<0.05).
### Table 3
Effect of Ecklonia stolonifera extracts on VFA by mixed rumen microbial fermentation
Incubation time (h) Treatments1) SEM Contrast
CON TRT 1 TRT 2 TRT 3 Linear Quadratic
Total VFA concentration (mM/g)
3 72.00ab 81.08a 67.62b 65.35b 2.85 0.0305 0.0814
12 79.12 88.59 79.13 79.05 4.04 0.6079 0.2714
24 101.92 96.37 88.34 88.23 10.06 0.3069 0.7936
48 118.93a 102.76b 95.56b 100.16b 4.44 0.0127 0.0477
72 189.75 178.98 191.12 202.28 22.52 0.6347 0.6393
Acetic acid concentration (mM/g)
3 51.63 59.29 49.26 47.29 2.77 0.1000 0.1204
12 57.94 64.03 56.69 55.60 3.06 0.3241 0.2740
24 73.81 68.96 61.40 59.25 9.49 0.2619 0.8903
48 85.77a 71.11b 61.79b 67.27b 3.54 0.0035 0.0218
72 153.63 142.62 153.83 165.37 22.82 0.6613 0.6344
Propionic acid concentration (mM/g)
3 11.27 13.92 11.22 10.80 2.08 0.6705 0.4808
12 11.72 15.55 13.06 13.88 1.74 0.6222 0.4129
24 18.55 18.34 16.41 19.28 0.95 0.9536 0.1441
48 22.13 21.98 21.86 21.81 1.36 0.8631 0.9670
72 24.72 25.07 24.57 25.03 0.60 0.8713 0.9336
Butyric acid concentration (mM/g)
3 4.55a 3.94b 3.57b 3.63b 1.36 0.0016 0.0555
12 4.73 4.50 4.69 4.79 0.76 0.8562 0.7160
24 4.78 4.54 5.27 4.85 0.51 0.8139 0.9251
48 5.51 4.84 5.96 5.54 0.20 0.7575 0.8815
72 5.70 5.64 6.36 5.94 0.99 0.6516 0.7975
A/P ratio
3 5.39 4.27 4.98 4.94 0.73 0.9177 0.6993
12 5.63 4.12 4.50 4.01 0.69 0.2236 0.5216
24 3.98 3.75 3.81 3.07 0.57 0.2803 0.6290
48 3.89a 3.24ab 2.86b 3.09b 0.60 0.0150 0.0607
72 6.24 5.74 6.26 6.62 0.96 0.7152 0.6738
VFA, volatile fatty acids; SEM, standard error of the mean; A/P ratio, acetate to propionate acid ratio.
1)
Dietary treatments were as follows: CON, basal diet (without Ecklonia stolonifera extract); TRT 1, 1% Ecklonia stolonifera; TRT 2, 3% Ecklonia stolonifera; TRT 3, 5% Ecklonia stolonifera on a substrate (timothy hay) basis.
a,b
Means with different superscripts in the same row indicate significant differences (p<0.05).
### Table 4
Effect of Ecklonia stolonifera extracts on in vitro gas and ammonia production by mixed rumen fermentation
Incubation time (h) Treatments1) SEM Contrast
CON TRT 1 TRT 2 TRT 3 Linear Quadratic
Methane emission (mL/g DM)
3 8.79bc 6.63c 12.88a 11.71ab 1.11 0.0168 0.6698
12 10.70 13.77 15.06 17.34 2.02 0.0465 0.8510
24 22.21 15.34 27.10 20.13 4.95 0.8090 0.9923
48 27.28 24.67 26.13 22.57 2.15 0.2247 0.8331
72 31.92 32.45 26.20 30.28 7.06 0.7329 0.8072
Carbon dioxide production (mL/g DM)
3 7.28 13.08 6.05 6.10 2.56 0.3839 0.2945
12 14.45 28.96 20.74 13.50 6.08 0.6948 0.1116
24 18.00 34.76 34.53 15.74 9.87 0.8780 0.1096
48 30.62 42.25 38.56 31.33 12.30 0.9781 0.4651
72 52.47 43.25 44.93 31.40 6.58 0.0698 0.7521
Hydrogen production (mL/g DM)
3 1.40b 0.94b 3.04a 2.56a 0.32 0.0047 0.9803
12 3.25 3.66 4.22 4.24 0.30 0.0283 0.5330
24 4.26 4.23 5.56 4.80 0.95 0.5072 0.7113
48 5.30 4.35 7.67 6.44 2.05 0.4833 0.9470
72 8.78b 8.32b 9.48b 24.12a 3.83 0.0248 0.0838
Ammonia production (mg/dL)
3 2.60 2.51 2.47 3.51 0.73 0.4365 0.4623
12 3.44 3.40 3.24 5.11 0.69 0.1563 0.2049
24 5.53a 4.91ab 3.51b 5.62a 0.57 0.6709 0.0447
48 9.38 9.78 9.38 9.40 0.60 0.9044 0.7609
72 13.40b 13.04b 13.82b 16.98a 0.96 0.0284 0.1061
SEM, standard error of the mean; DM, dry matter.
1)
Dietary treatments were as follows: CON, basal diet (without Ecklonia stolonifera extract); TRT 1, 1% Ecklonia stolonifera; TRT 2, 3% Ecklonia stolonifera; TRT 3, 5% Ecklonia stolonifera on a substrate (timothy hay) basis.
a–c
Means with different superscripts in the same row indicate significant differences (p<0.05).
### Table 5
Effect of Ecklonia stolonifera extracts on rumen microbial growth rate, protein and glucose concentration
Incubation (h) Treatments1) SEM Contrast
CON TRT 1 TRT 2 TRT 3 Linear Quadratic
Microbial growth rate (OD at 550 nm)
3 0.33 0.33 0.34 0.25 0.03 0.1142 0.1683
12 0.35 0.31 0.36 0.30 0.02 0.4335 0.5646
24 0.28 0.32 0.28 0.28 0.03 0.8478 0.5006
48 0.32b 0.38ab 0.37ab 0.43a 0.03 0.0295 1.0000
72 0.27 0.29 0.33 0.24 0.03 0.7287 0.0977
Protein concentration (mM/g)
3 0.14 0.16 0.15 0.15 0.01 0.5664 0.5868
12 0.19a 0.16b 0.15b 0.16b 0.01 0.0323 0.0490
24 0.24a 0.19b 0.18b 0.19b 0.01 0.0017 0.0089
48 0.27 0.20 0.18 0.21 0.03 0.2304 0.1758
72 0.28 0.23 0.23 0.23 0.04 0.4818 0.6027
Glucose concentration (mL/mg)
3 0.10ab 0.10b 0.11ab 0.12a 0.01 0.0418 0.0868
12 0.11 0.10 0.12 0.13 0.01 0.1268 0.3292
24 0.14 0.12 0.16 0.15 0.03 0.5625 0.8210
48 0.17 0.15 0.16 0.16 0.03 0.9801 0.7620
72 0.34 0.19 0.31 0.27 0.13 0.8968 0.6775
SEM, standard error of the mean; OD, optical density.
1)
Dietary treatments were as follows: CON, basal diet (without Ecklonia stolonifera extract); TRT 1, 1% Ecklonia stolonifera; TRT 2, 3% Ecklonia stolonifera; TRT 3, 5% Ecklonia stolonifera on a substrate (timothy hay) basis.
a,b
Means with different superscripts in the same row indicate significant differences (p<0.05).
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8156176805496216, "perplexity": 21729.16797700496}, "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-2020-05/segments/1579250613416.54/warc/CC-MAIN-20200123191130-20200123220130-00200.warc.gz"}
|
https://eprint.iacr.org/2019/1016
|
## Cryptology ePrint Archive: Report 2019/1016
Quantum Algorithms for the Approximate $k$-List Problem and their Application to Lattice Sieving
Elena Kirshanova and Erik Mårtensson and Eamonn W. Postlethwaite and Subhayan Roy Moulik
Abstract: The Shortest Vector Problem (SVP) is one of the mathematical foundations of lattice based cryptography. Lattice sieve algorithms are amongst the foremost methods of solving SVP. The asymptotically fastest known classical and quantum sieves solve SVP in a $d$-dimensional lattice in $2^{cd + o(d)}$ time steps with $2^{c'd + o(d)}$ memory for constants $c, c'$. In this work, we give various quantum sieving algorithms that trade computational steps for memory.
We first give a quantum analogue of the classical $k$-Sieve algorithm [Herold--Kirshanova--Laarhoven, PKC'18] in the Quantum Random Access Memory (QRAM) model, achieving an algorithm that heuristically solves SVP in $2^{0.2989d + o(d)}$ time steps using $2^{0.1395d + o(d)}$ memory. This should be compared to the state-of-the-art algorithm [Laarhoven, Ph.D Thesis, 2015] which, in the same model, solves SVP in $2^{0.2653d + o(d)}$ time steps and memory. In the QRAM model these algorithms can be implemented using $poly(d)$ width quantum circuits.
Secondly, we frame the $k$-Sieve as the problem of $k$-clique listing in a graph and apply quantum $k$-clique finding techniques to the $k$-Sieve.
Finally, we explore the large quantum memory regime by adapting parallel quantum search [Beals et al., Proc. Roy. Soc. A'13] to the $2$-Sieve and giving an analysis in the quantum circuit model. We show how to heuristically solve SVP in $2^{0.1037d + o(d)}$ time steps using $2^{0.2075d + o(d)}$ quantum memory.
Category / Keywords: foundations / approximate k-list problem, cryptanalysis, distributed computation, grover's algorithm, lattice sieving, nearest neighbour algorithms, quantum cryptography, shortest vector problem, SVP
Original Publication (with major differences): IACR-ASIACRYPT-2019
|
{"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": 2, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "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": 0.8044134974479675, "perplexity": 3081.7261088570185}, "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-2021-43/segments/1634323585450.39/warc/CC-MAIN-20211022021705-20211022051705-00625.warc.gz"}
|
https://en.cppreference.com/w/cpp/experimental/fs/path/path
|
# std::experimental::filesystem::path::path
< cpp | experimental | fs | path
path(); (1) (filesystem TS) path( const path& p ); (2) (filesystem TS) path( path&& p ); (3) (filesystem TS) template< class Source > path( const Source& source ); (4) (filesystem TS) template< class InputIt > path( InputIt first, InputIt last ); (5) (filesystem TS) template< class Source > path( const Source& source, const std::locale& loc ); (6) (filesystem TS) template< class InputIt > path( InputIt first, InputIt last, const std::locale& loc ); (7) (filesystem TS)
Constructs a new path object.
1) Constructs an empty path.
2) Copy constructor. Constructs a copy of p.
3) Move constructor. Constructs a copy of p, p is left in valid but unspecified state.
4-5) Constructs the path from a character sequence provided by source (4), which is a pointer or an input iterator to a null-terminated character/wide character sequence or an std::basic_string, or represented as a pair of input iterators [first, last) (5). Any of the four character types char, char16_t, char32_t, wchar_t is allowed, and the method of conversion to the native character set depends on the character type used by source
• If the source character type is char, the encoding of the source is assumed to be the native narrow encoding (so no conversion takes place on POSIX systems)
• If the source character type is char16_t, conversion from UTF-16 to native filesystem encoding is used.
• If the source character type is char32_t, conversion from UTF-32 to native filesystem encoding is used.
• If the source character type is wchar_t, the input is assumed to be the native wide encoding (so no conversion takes places on Windows)
6-7) Constructs the path from a character sequence provided by source (6), which is a pointer or an input iterator to a null-terminated character sequence or an std::string, or represented as a pair of input iterators [first, last) ((7)). The only character type allowed is char. Uses loc to perform the character encoding conversion. If value_type is wchar_t, converts from to wide using the std::codecvt<wchar_t, char, std::mbstate_t> facet of loc. Otherwise, first converts to wide using the std::codecvt<wchar_t, char, std::mbstate_t> facet and then converts to filesystem native character type using std::codecvt<wchar_t,value_type> facet of loc.
## Contents
### Parameters
p - a path to copy source - a std::basic_string, pointer to a null-terminated character string, or an input iterator with a character value type that points to a null-terminated character sequence (the character type must be char for overload (6) first, last - pair of LegacyInputIterators that specify a UTF-8 encoded character sequence loc - locale that defines encoding conversion to use Type requirements -InputIt must meet the requirements of LegacyInputIterator. -The value type of InputIt must be one of the four character types char, wchar_t, char16_t and char32_t to use the overload (5)) -The value type of InputIt must be char to use the overload (7))
### Exceptions
1-2) (none)
3)
noexcept specification:
noexcept
4-7) (none)
### Notes
For portable pathname generation from Unicode strings, see u8path.
### Example
#include <iostream>
#include <experimental/filesystem>
namespace fs = std::experimental::filesystem;
int main()
{
fs::path p1 = "/usr/lib/sendmail.cf"; // portable format
fs::path p2 = "C:\\users\\abcdef\\AppData\\Local\\Temp\\"; // native format
fs::path p3 = L"D:/猫.txt"; // wide string
std::cout << "p1 = " << p1 << '\n'
<< "p2 = " << p2 << '\n'
<< "p3 = " << p3 << '\n';
}
Output:
p1 = "/usr/lib/sendmail.cf"
p2 = "C:\users\abcdef\AppData\Local\Temp\"
p3 = "D:/猫.txt"
u8path creates a path from a UTF-8 encoded source (function)
|
{"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": 0.34813231229782104, "perplexity": 17695.4923887134}, "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-2020-24/segments/1590347404857.23/warc/CC-MAIN-20200529121120-20200529151120-00161.warc.gz"}
|
http://www.billthelizard.com/2010_01_01_archive.html
|
Saturday, January 30, 2010
Interesting Miscellany
Here are some of the links I've found interesting enough to tweet or retweet in that past several weeks.
Programming
A beautiful obfuscated Pi calculator
Programming language trends of 2009
Science
Leonardo da Vinci's resume
Richard Dawkins: Growing up in the universe
Richard Hamming: You and your research
Math
A quick little puzzle (in probability)
Euler Book Prize (A list to watch in the future. Since the site isn't updated for 2010 yet, the winner was Euler's Gem by David S. Richeson.)
Miscellaneous
Succed Blog
50 Books Every Geek Should Read
SICP Exercise 1.21: Smallest Divisor
From SICP section 1.2.6 Example: Testing for Primality
Exercise 1.21 asks us to use the smallest-divisor procedure to find the smallest divisor of each of the following numbers: 199, 1999, 19999.
The smallest-divisor procedure was given earlier in the section.
(define (smallest-divisor n) (find-divisor n 2))(define (find-divisor n test-divisor) (cond ((> (square test-divisor) n) n) ((divides? test-divisor n) test-divisor) (else (find-divisor n (+ test-divisor 1)))))(define (divides? a b) (= (remainder b a) 0))
This procedure makes use of the square procedure that was defined earlier. You'll need to include it if you want to run the code in an interpreter.
(define (square x) (* x x))
The smallest-divisor procedure finds the smallest integral divisor (greater than 1) of a given number n in a straightforward way, by testing to see if n is divisible by each integer from 2 to √n. Since the number of steps is between 1 and √n, the order of growth of the algorithm is O(√n).
We can find the solutions to the exercise by simply running the code in an interpreter.
> (smallest-divisor 199)199> (smallest-divisor 1999)1999> (smallest-divisor 19999)7
As you can see, the first two numbers are prime because they are their own smallest divisor, but the third is divisible by 7.
Related:
For links to all of the SICP lecture notes and exercises that I've done so far, see The SICP Challenge.
Tuesday, January 26, 2010
SICP Exercise 1.20: GCD
From SICP section 1.2.5 Greatest Common Divisors
Exercise 1.20 asks us to consider the following iterative procedure that uses Euclid's Algorithm to comput the GCD:
(define (gcd a b) (if (= b 0) a (gcd b (remainder a b))))
We're asked to illustrate the process generated by this procedure when using normal-order and applicative-order evaluation rules to evaluate (gcd 206 40). How many remainder operations are actually performed using each evaluation model?
We learned the rules for both applicative-order and normal-order evaluation back in SICP section 1.1.5 The Substitution Model for Procedure Application. We learned that under normal-order evaluation rules, the interpreter fully expands a procedure before reducing it. Operand expressions are substituted for parameters until an expression involving only primitive operators is reached. Under applicative-order rules, arguments are evaluated before operators are applied. This can often avoid multiple unnecessary evaluations of the same expression, which is one of the reasons why Lisp uses applicative-order evaluation.
In section 1.1.6 Conditional Expressions and Predicates (see exercise 1.5) we're told to assume that the evaluation rule for the special form if is the same whether we use normal or applicative order evaluation. "The predicate expression is evaluated first, and the result determines whether to evaluate the consequent or the alternative expression." We'll continue using this assumption until we're told otherwise.
Now let's put all of this together to illustrate both processes for (gcd 206 40).
Normal-order evaluation - fully expand and then reduce.
(gcd 206 40)(if (= 40 0) 206 (gcd 40 (remainder 206 40)))(gcd 40 (remainder 206 40))(if (= (remainder 206 40) 0) 40 (gcd (remainder 206 40) (remainder 40 (remainder 206 40))))(if (= 6 0) ;; 1 remainder evaluated 40 (gcd (remainder 206 40) (remainder 40 (remainder 206 40))))(gcd (remainder 206 40) (remainder 40 (remainder 206 40)))(if (= (remainder 40 (remainder 206 40)) 0) (remainder 206 40) (gcd (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40)))))
At this point both of the nested remainder operations that were substituted in for b in the (= b 0) procedure need to be evaluated. I'll combine these and show them as one step.
(if (= 4 0) ;; 2 remainders evaluated (remainder 206 40) (gcd (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40)))))(gcd (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40))))(if (= (remainder (remainder 206 40) (remainder 40 (remainder 206 40))) 0) (remainder 40 (remainder 206 40)) (gcd (remainder (remainder 206 40) (remainder 40 (remainder 206 40))) (remainder (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40))))))
Here again, multiple nested remainder operations that were substituted in for b in the (= b 0) procedure need to be evaluated. I'll combine all four and show them as one step.
(if (= 2 0) ;; 4 remainders evaluated (remainder 40 (remainder 206 40)) (gcd (remainder (remainder 206 40) (remainder 40 (remainder 206 40))) (remainder (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40))))))(gcd (remainder (remainder 206 40) (remainder 40 (remainder 206 40))) (remainder (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40)))))(if (= (remainder (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40)))) 0) (remainder (remainder 206 40) (remainder 40 (remainder 206 40))) (gcd (remainder (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40)))) (remainder (remainder (remainder 206 40) (remainder 40 (remainder 206 40))) (remainder (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40)))))))
There are seven nested remainder operations to evaluate at this point.
(if (= 0 0) ;; 7 remainders evaluated (remainder (remainder 206 40) (remainder 40 (remainder 206 40))) (gcd (remainder (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40)))) (remainder (remainder (remainder 206 40) (remainder 40 (remainder 206 40))) (remainder (remainder 40 (remainder 206 40)) (remainder (remainder 206 40) (remainder 40 (remainder 206 40)))))))(remainder (remainder 206 40) (remainder 40 (remainder 206 40)))
Finally, we can evaluate these four remainder operations to come up with the answer (GCD) and the total.
2 ;; 18 total remainders evaluated
Applicative-order evaluation - evaluate arguments and then apply operands. This one is a little bit easier to follow. With each substitution, we just evaluate the operands that we need before applying the operators at each step.
(gcd 206 40)(if (= 40 0) 206 (gcd 40 (remainder 206 40))))(gcd 40 (remainder 206 40))(gcd 40 6) ;; 1st remainder evaluated(if (= 6 0) 40 (gcd 6 (remainder 40 6)))(gcd 6 (remainder 40 6))(gcd 6 4) ;; 2nd remainder evaluated(if (= 4 0) 6 (gcd 4 (remainder 6 4)))(gcd 4 (remainder 6 4))(gcd 4 2) ;; 3rd remainder evaluated(if (= 2 0) 4 (gcd 2 (remainder 4 2)))(gcd 2 (remainder 4 2))(gcd 2 0) ;; 4th remainder evaluated(if (= 0 0) 2 (gcd 0 (remainder 2 0)))2
As you can see, using applicative-order evaluation, remainder was only evaluated four times, compared to 18 times using normal-order evaluation.
Related:
For links to all of the SICP lecture notes and exercises that I've done so far, see The SICP Challenge.
Saturday, January 23, 2010
Unsolved: Odd Perfect Numbers
A perfect number is a number that is the sum of its proper divisors (i.e., including 1 but excluding itself).
For example, the smallest perfect number is 6.
1 + 2 + 3 = 6
The next two perfect numbers are
1 + 2 + 4 + 7 + 14 = 28
1 + 2 + 4 + 8 + 16 + 31 + 62 + 124 + 248 = 496
See sequence A000396 in OEIS for a list of the first ten perfect numbers.
On a related note, a number that is smaller than the sum of its proper divisors is an abundant number, while a number greater than the sum of its proper divisors is called deficient. The smallest abundant number is 12, whose proper divisors sum to 16.
All of the perfect numbers that have been discovered so far are even.
The problem is to find an odd perfect number, or prove that no odd perfect numbers exist.
If there is an odd perfect number, we already know a lot about it. It must be at least 300 digits long, with at least 75 prime factors, at least 9 of them distinct. Its largest prime factor must be greater than 100,000,000. Its second largest prime factor is greater than 10,000, and its third largest is greater than 100.
Friday, January 22, 2010
SICP Exercise 1.19: Computing Fibonacci numbers
From SICP section 1.2.4 Exponentiation
Exercise 1.19 asks us to complete a procedure for computing Fibonacci numbers in a logarithmic number of steps. The following code is given:
(define (fib n) (fib-iter 1 0 0 1 n))(define (fib-iter a b p q count) (cond ((= count 0) b) ((even? count) (fib-iter a b <??> ; compute p' <??> ; compute q' (/ count 2))) (else (fib-iter (+ (* b q) (* a q) (* a p)) (+ (* b p) (* a q)) p q (- count 1)))))
We're reminded of the transformation of the state variables a and b in the original fib-iter procedure from section 1.2.2: a ← a + b and b ← a. If these state changes are labeled transformation T, then applying T repeatedly for n iterations starting with a = 1 and b = 0 produces the pair a = Fib(n + 1) and b = Fib(n). So the Fibonacci numbers are produced by the nth power of the transformation T, or Tn, starting with the pair (1, 0).
We are then asked to consider the family of transformations Tpq which transforms the pair (a, b) according to the following rules:
a ← bq + aq + ap
b ← bp + aq
We can verify by quick substitution that the original transformation T is just a special case of Tpq, where p = 0 and q = 1.
a ← b(1) + a(1) + a(0)
a ← b + a
b ← b(0) + a(1)
b ← a
We are asked to show that if we apply Tpq twice, the effect is the same as using a single transformation Tp'q' of the same form, and compute p' and q' in terms of p and q. This will give us an explicit way to square these transformations, which we can use to compute Tn using successive squaring, just like the fast-expt procedure from exercise 1.16.
We can apply Tpq twice by defining new variables and using substitution. Let's define a1 and b1 as the results of applying transformation Tpq once
a1 = bq + aq + ap
b1 = bp + aq
The next step is to define a2 and b2 and apply the tranformation a second time, this time using a1 and b1 in place of a and b.
a2 = b1q + a1q + a1p
b2 = b1p + a1q
Now that we have a system of equations defined, we can use substitution on our way to simplifying.
a2 = (bp + aq)q + (bq + aq + ap)q + (bq + aq + ap)p
b2 = (bp + aq)p + (bq + aq + ap)q
The second equation is shorter, so it should be easier to manipulate. Remember, we're trying to find p' and q', so we need to rewrite the equation to fit the form
b2 = bp' + aq'
where p' and q' can be computed in terms of q and p.
b2 = (bp + aq)p + (bq + aq + ap)q
= (bpp + apq) + (bqq + aqq + apq)
= bpp + apq + bqq + aqq + apq
= (bpp + bqq) + (2apq + aqq)
= b(pp + qq) + a(2qp + qq)
From this we can see that p' and q' can be computed using the following equations:
p' = p2 + q2
q' = 2pq + q2
Manipulating the equation for a2 in the same way, we can verify those results. This time we're trying to fit the form
a2 = bq' + aq' + ap'
The groupings required for this manipulation are made even easier by the fact that we now already know the formulas for p' and q'.
a2 = (bp + aq)q + (bq + aq + ap)q + (bq + aq + ap)p
= (bpq + aqq) + (bqq + aqq + apq) + (bpq + apq + app)
= bpq + aqq + bqq + aqq + apq + bpq + apq + app
= (bpq + bpq + bqq) + (apq + apq + aqq) + (app + aqq)
= b(pq + pq + qq) + a(pq + pq + qq) + a(pp + qq)
= b(2pq + qq) + a(2pq + qq) + a(pp + qq)
Now that we've verified the formulas for p' and q' in terms of p and q, we can use them to complete the procedure we were given.
(define (fib n) (fib-iter 1 0 0 1 n))(define (fib-iter a b p q count) (cond ((= count 0) b) ((even? count) (fib-iter a b (+ (* p p) (* q q)) ; compute p' (+ (* 2 p q) (* q q)) ; compute q' (/ count 2))) (else (fib-iter (+ (* b q) (* a q) (* a p)) (+ (* b p) (* a q)) p q (- count 1)))))
You can test several known values in an interpreter to verify that this actually works.
> (fib 0)0> (fib 1)1> (fib 2)1> (fib 3)2> (fib 5)5> (fib 10)55> (fib 20)6765
Related:
For links to all of the SICP lecture notes and exercises that I've done so far, see The SICP Challenge.
Thursday, January 14, 2010
SICP Exercise 1.18: Iterative multiplication
From SICP section 1.2.4 Exponentiation
Exercise 1.18 asks us to use the results from the two previous exercises (1.16 and 1.17) to devise a procedure that generates an iterative process for multiplying two integers in terms of adding, doubling and halving, and which uses a logarithmic number of steps.
The key idea from exercise 1.16 was to keep an additional state variable a, and manipulate the state transition so that the product (a * bn) remained unchanged. We can modify our solution to exercise 1.17 to use the same idea. Since we're now dealing with multiplication instead of exponentiation, the invariant quantity will be (a * b + p) where a and b are the two operands, and p will be our state variable. Initially p will be 0, but by the end of the iterative process it will hold the product (a * b).
(define (even? n) (= (remainder n 2) 0))(define (double x) (+ x x))(define (halve x) (/ x 2))(define (mult-iter a b p) (cond ((= 0 b) p) ((even? b) (mult-iter (double a) (halve b) p)) (else (mult-iter a (- b 1) (+ a p)))))(define (mult a b) (mult-iter a b 0))
Related:
For links to all of the SICP lecture notes and exercises that I've done so far, see The SICP Challenge.
Wednesday, January 13, 2010
SICP Exercise 1.17: Multiplication by repeated addition
From SICP section 1.2.4 Exponentiation
Exercise 1.17 asks us to design a multiplication procedure analogous to fast-expt that uses a logarithmic number of steps. We're told that in addition to adding, we can use procedures for doubling or halving an integer argument.
(define (double x) (+ x x))(define (halve x) (/ x 2))
We'll also use the same even? procedure we've seen before:
(define (even? n) (= (remainder n 2) 0))
The following multiplication procedure that takes a linear number of steps is given:
(define (* a b) (if (= b 0) 0 (+ a (* a (- b 1)))))
This procedure defines multiplication in terms of the algorithm we all learned in grade school: add a to itself b times.
The exercise also makes reference to the following fast-expt procedure, which we can use as a guide:
(define (fast-expt b n) (cond ((= n 0) 1) ((even? n) (square (fast-expt b (/ n 2)))) (else (* b (fast-expt b (- n 1))))))
This procedure makes use of the following observations:
bn = (bn/2)2 if n is even
bn = b * bn-1 if n is odd
We can define similar rules for integer multiplication.
a * b = 2 * (a * b/2) if be is even
a * b = a + a * (b - 1) if b is odd
The first rule tells us when to use our procedures double and halve. The second rule just lets us take an odd b and make it even in preparation for the next iteration. Translating these rule into a Scheme procedure give us:
(define (fast-mult a b) (cond ((= b 0) 0) ((= b 1) a) ((even? b) (double (fast-mult a (halve b)))) (else (+ a (fast-mult a (- b 1))))))
The procedure takes a logarithmic number of steps. If you double the size of the input parameter b, the procedure takes only one more step to compute the product.
Related:
For links to all of the SICP lecture notes and exercises that I've done so far, see The SICP Challenge.
Tuesday, January 12, 2010
Guest article on Programming Praxis
I was excited to be asked to be the guest author for an article on one of my favorite programming blogs, Programming Praxis. If you're not familiar with the site, Programming Praxis provides weekly practice exercieses to "sharpen your saw" on. It was inspired in part by Project Euler, but the problems on Programming Praxis focus more on developing programming skills and usually require less advanced math than those on Project Euler.
To follow up earlier exercises on Calculating Pi and Logarithms, my article is on Calculating Sines using two different methods, the Taylor series and the Triple-angle formula. The sample solutions are written in Scheme, but readers are encouraged to submit solutions in any language they choose (see the HOWTO on posting source code to post your own solution). Since I'm still a relative newbie to Scheme (I'm currently still in chapter one of SICP), I'll be interested to see what alternate solutions you can come up with.
The article is also currently featured on Planet Scheme.
Monday, January 11, 2010
SICP Exercise 1.16: Fast Exponentiation
From SICP section 1.2.4 Exponentiation
Exercise 1.16 asks us to design an exponentiation procedure that evolves an iterative process using successive squaring and uses a logarithmic number of steps. A hint tells us to use the observation that (bn/2)2 = (b2)n/2 and to keep, along with the exponent n and base b, an additional state variable a, and to define the state transformation in such a way that the product a * bn is unchanged from state to state. The value of a should start at 1, and should contain the final answer by the end of the process.
Earlier in section 1.2.4, we were given the procedure:
(define (even? n) (= (remainder n 2) 0))
which tests whether an integer is even. This will come in handy again for this exercise, since we'll need to adjust a by a different amount when n is even than when n is odd.
We'll also use the following simple procedure for squaring a number:
(define (square x) (* x x))
With those building blocks in place, we can define our iterative procedure.
(define (expt-iter b n a) (cond ((= n 0) a) ((even? n) (expt-iter (square b) (/ n 2) a)) (else (expt-iter b (- n 1) (* a b)))))
We call the procedure expt-iter with the arguments base b, exponent n, and the state variable a. The first thing we do is check to see if the exponent is 0. If so, we've reached the end of the procedure and just return the value of a. Next we check to see if n is even. If it is, we use the observation that (bn/2)2 = (b2)n/2 to transform state information by squaring b and dividing n by 2. Finally, if n is odd we transform state information by reducing n by 1 and multiplying a by the base b.
The only thing that's left to do is define a procedure that calls expt-iter with the correct initial values.
(define (fast-expt b n) (expt-iter b n 1))
Here are a few sample runs of the procedure:
> (fast-expt 2 2)4> (fast-expt 2 3)8> (fast-expt 2 10)1024> (fast-expt 3 3)27> (fast-expt 5 5)3125
You can try running the procedure with large values of n to verify that it really is fast.
Related:
For links to all of the SICP lecture notes and exercises that I've done so far, see The SICP Challenge.
Sunday, January 10, 2010
Math visualization: Multiplying Two Binomials
In my earlier post Math visualization: (x + 1)2, I showed how to draw a picture that proved the equality
(x + 1)2 = x2 + 2x + 1
An alert reader commented that (x + 1)2 is a specific instance of the binomial squared
(x + a)2 = x2 + 2ax + a2
Here's a visualization of that equality:
It turns out that the illustration can be generalized a little bit further to cover multiplying two binomials that form a rectangle (not just a perfect square).
(x + a)(x + b) = x2 + ax + bx + ab
If you want to see how this idea can be extended into the third dimension, check out Montessori World's page on the Binomial Cube.
Monday, January 4, 2010
Unsolved: Twin Primes Conjecture
Prime numbers, as most school children can tell you, are those numbers that are evenly divisible by only themselves and 1. The first few primes are
2, 3, 5, 7, 11, 13, 17...
We've known that there are infinitely many primes since c. 300 BC when it was proven by Euclid of Alexandria. Euclid used a very simple and elegant proof by contradiction.
Euclid's proof of the infinitude of primes
First, assume that there are a finite number of primes, p1, p2, p3, ..., pn.
Now let
Q = (p1 * p2 * ... * pn) + 1
That is, Q is equal to all of the primes multiplied together plus one.
By the Fundamental Theorem of Arithmetic, Q is either prime or it can be written as the product of two or more primes. However, none of the primes in our list evenly divides Q. If any prime in our list did evenly divide Q, then that same prime would also evenly divide 1, since
Q - (p1 * p2 * ... * pn) = 1
This contradicts the assumption that we had listed all the primes. So no matter how many primes we start with in our list, there must always be more primes. (Note that this proof does not claim that Q itself is prime, just that there must be some prime not in the initial list.)
Twin primes
Twin primes are those pairs of numers that have a difference of two, and that are both prime.
3, 5
5, 7
11, 13
17, 19
...
The Twin prime conjecture, which dates back to the 18th century, simply states that there are infinitely many twin primes.
Given the simplicity of Euclid's proof of the infinitude of primes, it's tempting to hope for an equally simple proof to the Twin prime conjecture. Needless to say, such a proof has not been found.
|
{"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": 0.6603094935417175, "perplexity": 2667.7163791430526}, "config": {"markdown_headings": false, "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-2018-05/segments/1516084893530.89/warc/CC-MAIN-20180124070239-20180124090239-00597.warc.gz"}
|
https://www.mail-archive.com/search?l=lyx-users%40lists.lyx.org&q=date:20081117&o=newest&f=1
|
### Re: \bind-files (Mac, 1.6)
Nick Bell wrote:
To try to put them back I put
\bind-file mac
Err that's the problem - it should be \bind_file mac not \bind-file mac.
~Nick
### Change names of TOC? Bibliography?
Does anyone know how to change the name of this section? In Lyx
report(koma-script) it prints out by default as Contents. Can I make it
Also, can I change the default name of the Bibliography as well?
I tried adding the following to the preamble, but it doesn't seem to have
an effect:
\renewcommand{\bibname}{List of References}
I am using the 'bibtotoc' option in the arguments to the document class.
What's the difference between this and using the following ERT TEX code?
With the hyperref package, the bibliography is hyperlinked to the TOC entry,
but if I use the bookmarks menu on the left in Acrobat, clicking on
Bibliography takes me to the title page of my document instead!
Alex
### Re: Lyx 1.6.0: icons on toolbar
- Mail Original -
De: alain didierjean [EMAIL PROTECTED]
À: lyx-users [email protected]
Envoyé: Samedi 15 Novembre 2008 18:13:08 GMT +01:00 Amsterdam / Berlin /
Berne / Rome / Stockholm / Vienne
Objet: Lyx 1.6.0: icons on toolbar
I Just downloaded the gentto package for lyx 1.6.0 : it compliles OK and
seems nice, but display toolbars with text (in french), not icons. It's
almost unusable. How do I get the icons back ? a utility ? a complie option ?
I fi go back to v.1.5.6, I get the icons all right...
SOLVED by emerge --update --newuse --deep --resume world
I'll never know what was wrong...
--
### Re: LyX 1.6.0. breaks down all the time
Benno Bühler wrote:
Hi,
I just changed from LyX 1.5.6 to 1.6.0 and I really like the new features of
the program…but: Somehow LyX crashes all the time. For example when I am
opening MS Outlook?!?
Yep, this has happened to me with all beta/RC versions too (for me, it
was more excel, but I could trigger it with other soft as well).
Unfortunately, there is no easy reproducible way to reproduce it on
demand...
Maybe it has to do something with the installer? Previously, I used the
alternative installer, to install LyX 1.6.0. (Windows XP) I used the
standard installer.
No, as I wrote above, I had this bug with all RC and betas, which were
the alternative installers. This bug seems to be affecting both build
families...
How can I access the log-file of the crashes? There pops up a window of LyX,
saying that I found a bug. But I cannot fully read or copy/paste the text.
IIRC, Windows XP saves them somewhere in your Local Settings\Temp
directory. Or somewhere around.
Best regards,
Olivier.
PS:
This bug was reported on devel-ML by Edwin Leuven under the title
lyx rc3 crashing all the time.
I also mentioned it here on October 24th in a thread about RC4 on the
user list.
Regards
Benno
### Change names of TOC? Bibliography?
Does anyone know how to change the name of this section? In Lyx
report(koma-script) it prints out by default as Contents. Can I make it
Also, to change the default name of the Bibliography I tried adding the
following to the preamble, but it doesn't seem to have an effect:
\renewcommand{\bibname}{List of References}
If I add this as ERT code right before the Bibliography in my LyX document,
the name is now changed in the PDF output. How come?
Also, I noticed how when compiling my LyX document oftentimes only one Latex
run is completed instead of two! In these cases, although I have the 'intoc'
option for my document, the Nomenclature does not appear in the TOC, although
I can see the entry when opening the .toc file manually.
Another funny thing, the same times when the Nomenclature doesn't appear in
the contents, the compiled PDF file also doesn't open automatically as it
should after being created. Instead, I have to look for it in the temp
directory and open it manually !!!
I am using the 'bibtotoc' option in the arguments to the document class.
(The bibliography appears in the Contents, even when the nomenclature doesn't!)
What's the difference between this and using the following ERT TEX code?
With the hyperref package, the bibliography is hyperlinked to the TOC entry,
but if I use the bookmarks menu on the left in Acrobat, clicking on
Bibliography takes me to the title page of my document instead!
Alex
### Re: LyX 1.6.0. breaks down all the time
Olivier Ripoll [EMAIL PROTECTED] writes:
Yep, this has happened to me with all beta/RC versions too (for me, it
was more excel, but I could trigger it with other soft as well).
Unfortunately, there is no easy reproducible way to reproduce it on
demand...
It would be nice to obtain a backtrace for that, but I do not know how
to do that in windows. The two causes I can think of are:
- clipboard: LyX hold the clipboard, and it loses it when another
application launches
- a focus problem
JMarc
### Re: \bind-files (Mac, 1.6)
Nick Bell [EMAIL PROTECTED] writes:
To try to put them back I put
\bind-file mac
It is \bind_file.
But it is easier to use the new shortcut editor, I guess.
JMarc
### Re: LyX 1.6.0. breaks down all the time
Olivier Ripoll [EMAIL PROTECTED] writes:
Benno Bühler wrote:
How can I access the log-file of the crashes? There pops up a window of LyX,
saying that I found a bug. But I cannot fully read or copy/paste the text.
IIRC, Windows XP saves them somewhere in your Local Settings\Temp
directory. Or somewhere around.
To copy/paste the log of the crash from the window saying you found a bug
(though I don't know how helpful that text is), you need to right-click in that
window and you can then Copy to Clipboard.
Go to a text editor and paste the contents!
Alex
### Re: LyX 1.6.0. breaks down all the time
Jean-Marc Lasgouttes wrote:
Olivier Ripoll [EMAIL PROTECTED] writes:
Yep, this has happened to me with all beta/RC versions too (for me, it
was more excel, but I could trigger it with other soft as well).
Unfortunately, there is no easy reproducible way to reproduce it on
demand...
It would be nice to obtain a backtrace for that, but I do not know how
to do that in windows. The two causes I can think of are:
- clipboard: LyX hold the clipboard, and it loses it when another
application launches
Bingo!
100% reproducible crash (3 out of 3) if I start excel after having
copied something in LyX.
100% no-crash if (2 out of 2) if I open excel with LyX open and have yet
not copied anything in LyX.
100% no-crash (2 out of 2) if I copy something in LyX, then copy
something in another application, then start excel. That's a nice
workaround for the short term.
I also explains why I was only seeing this bug in long sessions of LyX,
not in short ones (when trying to have a reproducible pattern for bugzilla).
PS: Yes, 7 tests is not very good statistically, but I guess that is
enough).
- a focus problem
JMarc
Should I open a bugzilla report or are you doing it?
Many thanks and best regards,
Olivier
### Print list of notes
Dear all,
Is there anyway in which I can print a list of notes, preferably with
page references?
Many thanks
~Nick
### Open a New Window in read-only mode?
Is it possible to open a new window in read-only mode, on a
lyx file that is r/w please?
I want to refer to previous sections of a document in
read-only mode in a new window, so I can keep a consistent
format for new sections written later in the same document.
TIA
Keith Roberts
-
Websites:
http://www.php-debuggers.net
http://www.karsites.net
Where will you spend Eternity?
http://www.fellowshiptractleague.org/tracts/images/PDF/tract_130.pdf
All email addresses are challenge-response protected with
TMDA [http://tmda.net]
-
### TOC in fullscreen
When entering full screen mode I sometimes get the table of contents
panel on the right. It is sporadic.
Anyone experience this?
### Re: TOC in fullscreen
Ivan Werning wrote:
panel on the right. It is sporadic.
Anyone experience this?
Yes, on my Mac. Haven't seen it on Windows.
~Nick
### Re: Print list of notes
Nick Bell wrote:
Dear all,
Is there anyway in which I can print a list of notes, preferably with
page references?
Many thanks
~Nick
What kind of notes ? footnotes, endnotes, to-do notes
Cheers,
Charles
--
http://www.kde-france.org
### re: Change names of TOC? Bibliography?
Does anyone know how to change the name of this section? In Lyx
report(koma-script) it prints out by default as Contents. Can I make it
yes
Also, to change the default name of the Bibliography I tried adding the
following to the preamble, but it doesn't seem to have an effect:
\renewcommand{\bibname}{List of References}
If I add this as ERT code right before the Bibliography in my LyX document,
the name is now changed in the PDF output. How come?
use this \renewcommand*{\bibname}{List of References}
I am using the 'bibtotoc' option in the arguments to the document class.
(The bibliography appears in the Contents, even when the nomenclature doesn't!)
What's the difference between this and using the following ERT TEX code?
if you just care for the bib to show up in the TOC, its the same; if you are
depending on other things like hyperref it will lead to different outcomes
With the hyperref package, the bibliography is hyperlinked to the TOC entry,
but if I use the bookmarks menu on the left in Acrobat, clicking on
Bibliography takes me to the title page of my document instead!
it should work, either you check your preferences or you could workaround with
setting up a hypertarget around your bibliography like this:
\hypertarget{YOURLABELNAME}{}
\pdfbookmark[0]{Bookmarkname}{YOURLABELNAME}
but then you will probably have to replace your bibtotoc option with KOMA by
Alex
cheers,
peerlynt
Pt! Schon vom neuen WEB.DE MultiMessenger gehört?
Der kanns mit allen: http://www.produkte.web.de/messenger/?did=3123
### Re: lyx2lyx script broken (1.6.0 on Vista)
Uwe Stöhr wrote:
Dominik Waßenhoven schrieb:
On the Vista machine, I had no Python installed and the lyx2lyx script
failed. I now installed Microsoft's VC++ redistributable package, as
suggested by Paul Rubin, and now the lyx2lyx script works. So I think
there is a problem with the python.exe and/or python26.dll which are in
the bin directory of LyX 1.6.
But I also had no Python installed on this Vista machine, only installed
LyX using my installer and it worked. I also got feedback that it works
for others too.
It appears the bundled Python requires a particular release of
Microsoft's C runtime. There are approximately a zillion releases of
the MSVC runtime, all mutually incompatible.
For years, Microsoft handled this by changing the name of the MSVC
runtime DLLs with each release. More recently, when someone decided
it'd be good to have more incompatible runtime versions than would fit
in a single MSVC release cycle, they invented the Side by Side
versioning method, which has the advantages of being a black box,
completely different from previous Windows DLL versioning mechanisms,
and entirely mysterious, opaque, and frustrating for users.
Side-by-Side sticks various releases of the MSVC runtime in
directories under %windir%\winsxs.
Product installers are supposed to include the MSVC redistributable
package for the particular MSVC version they need, which will get
installed in Side-by-Side if it's not already present.
Probably, people who don't have problems with the minimal Python
included with Uwe's installer already have the necessary MSVC
redistributable on their machine from some other product installation.
The fix would be to include the appropriate MSVC redistributable in
Uwe's LyX installer. Note that it may have to be updated any time the
Python binaries are updated, since they might be linked with a
different MSVC version.
Sure makes SVR4 shared object versioning look good, doesn't it?
--
Michael Wojcik
Micro Focus
Rhetoric Writing, Michigan State University
### Steps towards a portable LyX installation on Windows
Hi All
I made quite good progress producing a portable LyX installation based
on LyX 1.6.0. What would be the best place to post the instructions?
I think wiki.lyx.org may be suitable, but it looks a bit disorganised
at the moment, and it seems that only developers have access anyway
(?).
I used texlive 2008 as my tex installation, which already provides
some portability. I follow the same basic approach as tl-portable.bat,
but add the necessary environment variables for LyX, convert and
ghostscript. Apart from one problem between the bundled convert and
the bundled ghoscript, this works really well.
Regards,
Thomas
### Re: Open a New Window in read-only mode?
Keith Roberts [EMAIL PROTECTED] schrieb:
Is it possible to open a new window in read-only mode, on a
lyx file that is r/w please?
I want to refer to previous sections of a document in
read-only mode in a new window, so I can keep a consistent
format for new sections written later in the same document.
I do not know of a straightforward way to achieve this.
Depending on what exactly you intend, there are two ways that spring to my
mind:
a) ViewPDF (or ViewPS): the output is read-only of course.
b) open the file in a second lyx process, started as a different user with
Günter
### Re: Idiot's guide to creating a new style - or inset?
Steve Litt wrote:
On Sunday 16 November 2008 03:43:04 pm rgheck wrote:
Yes, that's what you need. Try something like this:
#\DeclareLyXModule{TextSuperSub}
#DescriptionBegin
#\theendnotes in ERT where you want the endnotes to appear.
#DescriptionEnd
Format 11
InsetLayout Custom:Superscript
LyXTypecustom
LatexNametextsuperscript
LatexTypecommand
Decoration classic
Font
SizeSmall
EndFont
MultiPar false
LabelStringsuper
End
and something similar for subscripts. Save it to textsupersub.module in
your LyX layouts directory and reconfigure. You can tweak it as you wish.
Hi Richard,
What's the difference bettween InsetLayout, CharacterStyle and Environment?
When would you use InsetLayout over one of the others?
InsetLayout is new in 1.6. It incorporates the old charstyle (LyXType
charstyle) and also these new custom insets, which look like footnotes
but do anything you like. Of course, textsuperscript could (and probably
should) be a charstyle.
What is the Decoration LyX property (set to classic in your example)?
This makes the inset look like a footnote: with a little button. There
are other choices, too: minimalistic (no button) and, uh, can't remember.
rh
### Re: Idiot's guide to creating a new style - or inset?
Nick Bell wrote:
rgheck wrote:
#\DeclareLyXModule{TextSuperSub}
#DescriptionBegin
#\theendnotes in ERT where you want the endnotes to appear.
#DescriptionEnd
Format 11
InsetLayout Custom:Superscript
LyXTypecustom
LatexNametextsuperscript
LatexTypecommand
Decoration classic
Font
SizeSmall
EndFont
MultiPar false
LabelStringsuper
End
That works brilliantly, thanks. Now how do I get the inset label to be
equal to the parameter (e.g. XYZ in \textsuperscript{XYZ})? Or should
I be using a user defined char style (??) ?
The label can't be modified. You could try a charstyle. You could also
try Decoration minimalistic.
rh
~Nick
### Re: LyX 1.6.0. breaks down all the time
I can reproduce the recipe from Olivier. I had reported that in this bug entry:
http://bugzilla.lyx.org/show_bug.cgi?id=5472
Still I do not know if we can call this a bug or a nice anti-Microsoft feature
:-D
Cheers,
Nicolás
Alex wrote:
Olivier Ripoll [EMAIL PROTECTED] writes:
Benno Bühler wrote:
How can I access the log-file of the crashes? There pops up a window of LyX,
saying that I found a bug. But I cannot fully read or copy/paste the text.
IIRC, Windows XP saves them somewhere in your Local Settings\Temp
directory. Or somewhere around.
To copy/paste the log of the crash from the window saying you found a bug
(though I don't know how helpful that text is), you need to right-click in that
window and you can then Copy to Clipboard.
Go to a text editor and paste the contents!
Alex
### Re: Steps towards a portable LyX installation on Windows
Thomas Steffen wrote:
I used texlive 2008 as my tex installation, which already provides
some portability. I follow the same basic approach as tl-portable.bat,
but add the necessary environment variables for LyX, convert and
ghostscript. Apart from one problem between the bundled convert and
the bundled ghoscript, this works really well.
The standard installer already bundles Ghostscript and ImageMagick in a
portable way (no registry keys need to be modified).
Joost
### Re: lyx2lyx script broken (1.6.0 on Vista)
Michael Wojcik wrote:
Uwe Stöhr wrote:
Dominik Waßenhoven schrieb:
On the Vista machine, I had no Python installed and the lyx2lyx script
failed. I now installed Microsoft's VC++ redistributable package, as
suggested by Paul Rubin, and now the lyx2lyx script works. So I think
there is a problem with the python.exe and/or python26.dll which are in
the bin directory of LyX 1.6.
But I also had no Python installed on this Vista machine, only installed
LyX using my installer and it worked. I also got feedback that it works
for others too.
It appears the bundled Python requires a particular release of
Microsoft's C runtime. There are approximately a zillion releases of
the MSVC runtime, all mutually incompatible.
For years, Microsoft handled this by changing the name of the MSVC
runtime DLLs with each release. More recently, when someone decided
it'd be good to have more incompatible runtime versions than would fit
in a single MSVC release cycle, they invented the Side by Side
versioning method, which has the advantages of being a black box,
completely different from previous Windows DLL versioning mechanisms,
and entirely mysterious, opaque, and frustrating for users.
Side-by-Side sticks various releases of the MSVC runtime in
directories under %windir%\winsxs.
Product installers are supposed to include the MSVC redistributable
package for the particular MSVC version they need, which will get
installed in Side-by-Side if it's not already present.
Probably, people who don't have problems with the minimal Python
included with Uwe's installer already have the necessary MSVC
redistributable on their machine from some other product installation.
The fix would be to include the appropriate MSVC redistributable in
Uwe's LyX installer. Note that it may have to be updated any time the
Python binaries are updated, since they might be linked with a
different MSVC version.
Sure makes SVR4 shared object versioning look good, doesn't it?
I wonder if disk manufacturers are paying M$to do this? I've got about 54MB of crap in %windir%\winsxs, with multiple versions of each set of files. Presumably there's no way for Windoze to know that something depending on an older version can use the newer version, so old versions never go away. Kind of like that half gigabyte (and counting) of patch files that never gets deleted. ### Re: Open a New Window in read-only mode? Keith Roberts wrote: Is it possible to open a new window in read-only mode, on a lyx file that is r/w please? I want to refer to previous sections of a document in read-only mode in a new window, so I can keep a consistent format for new sections written later in the same document. TIA Keith Roberts With LyX 1.6.0, you can open the doc and then use View - Split View into Left and Right Half (or View - Split View into Upper and Lower Half) to get two views on the same document. AFAIK neither is read-only, but hopefully you can restrain yourself from editing one of them. :-) /Paul ### Re: Steps towards a portable LyX installation on Windows On Mon, Nov 17, 2008 at 4:03 PM, Joost Verburg [EMAIL PROTECTED] wrote: The standard installer already bundles Ghostscript and ImageMagick in a portable way (no registry keys need to be modified). That sounds interesting. I know that LyXLauncher does some magic, but I was not able to figure out what it was. Is there any way to check what LyXLauncher does to the environment? Anyway, I have managed to put my experience down in the Wiki at http://wiki.lyx.org/Windows/PortableInstallation . It is certainly not easy or painless, but I think a few small changes could improve the process significantly. Maybe the issues I had are bugs? The first problem I had was related to the path. Ghostscript was not really happy, and for some reason convert would not find ghostscript. I had to do the following changes to get previews and eps-pdf conversion working (the first three lines may or may not be necessary, I did not test them individually): path %LYX_DIR%python;%path% path %LYX_DIR%bin;%path% path %LYX_DIR%imagemagick;%path% set GS_DIR=%LYX_DIR%ghostscript\ path %GS_DIR%bin;%path% set GS_LIB=%GS_DIR%lib;%GS_DIR%fonts;%GS_DIR%Resource The other issue was that convert would not recognise ghostscript. I read that @PSdelegate@ in delegates.xml relies on registry keys, and indeed replacing it with gswin32c.exe solved the issue. This was necessary to get previews working for eps files. Finally I keep getting an error message from reconfigure about chklatex.ltx, which caused by the platex check. It seems like the PLATEX variable is empty, and it calls the argument instead if cmdOutput(PLATEX + ' chklatex.ltx').find('pLaTeX2e') != -1: which is not recognised as an executable or an association. And then there is a problem with TeX Live 2008. The new portable function tl-portable.bat is very nice, but unfortunately it is so inflexible that it can only start a console, and not another program. Changing this may be easy, but it would require some advanced batch language tricks, which is not my specialty. Regards, Thomas ### Re: lyx2lyx script broken (1.6.0 on Vista) On Mon, Nov 17, 2008 at 11:07:05AM -0500, Paul A. Rubin wrote: I wonder if disk manufacturers are paying M$ to do this? I've got about
54MB of crap in %windir%\winsxs, with multiple versions of each set of
files. Presumably there's no way for Windoze to know that something
depending on an older version can use the newer version, so old versions
never go away.
In fact that's actually the most sensible behaviour since there are only
very few cases where a new version indeed can replace an older one
without any existing or imagined problem. In particular that would mean
not only source and binary but also behavioural compatibility including
keeping buggy behaviour. When you factor in that application also can
depend on runtime characteristics even optimizations might have to be
ruled out, so there's really not much left what could be done in a newer
version...
Andre'
### Re: Print list of notes
Charles de Miramon wrote:
Nick Bell wrote:
Is there anyway in which I can print a list of notes, preferably with
page references?
What kind of notes ? footnotes, endnotes, to-do notes
Lyx Notes
Thanks
Nick
### hfill
Hello,
Where is the hfill insert in lyx 1.6 ?
My binding doesn't work anymore !
Philippe Camus
### Re: Idiot's guide to creating a new style - or inset?
Richard Heck wrote the following on 17/11/2008:
The label can't be modified. You could try a charstyle. You could
also try Decoration minimalistic.
Charstyle works well, but I suppose I can't set the style of the
displayed label to super/subscript can I? (That would probably be a bit
WYSIWYG).
I've got more or less what I want with $_{\text{XYZ}}$ command sequences
bound to keys.
Thanks, Nick
### Re: hfill
[EMAIL PROTECTED] wrote:
Where is the hfill insert in lyx 1.6 ?
Insert Formatting Horizontal space
My binding doesn't work anymore !
space-insert hfill
Regards,
Dominik.-
### Query on printing with 'screens'
Hi all:
I'm a Lyx user in Goa, and hope you won't mind me intruding.
Every time I go in for a book, to be printed via offset, my printer
has a problem. He takes the PDF file and attempts to do crazy things
like importing it into Windows/Corel Draw, etc.
He says the photos won't print because they don't have a screen.
Query:
* Is he right?
* Is there some way of putting a screen on the photos? LyX takes TeX
commands, so maybe if there's one I could use it.
Earlier, he was struggling to find how to print the file laterally
inverted (mirror image), and we found the command after some search.
Best, FN
PS: A cc'd reply to me would be highly appreciated...
--
FN * Independent Journalist http://fn.goa-india.org
Blog: http://fredericknoronha.wordpress.com
M: +91-9822122436 P: +91-832-2409490
### Lyx 1.6 on ubuntu 8.04
Has anyone installed 1.6 on Ubuntu 8.04? Its available for Jaunty (as
pointed out elsewhere on this forum), but not sure of the risks that may
be involved.
I currently have 1.5.5 installed via the Ubuntu repository, should I
uninstall this before installing 1.6, or is it a bad idea to install 1.6
before its officially available for 8.04.
I am new to Linux, and still finding my feet with it.
Graham
### Re: Open a New Window in read-only mode?
Thanks Guenter. I want to view the lyx source code itself,
so I can use that as a pattern for more sections.
Keith
On Mon, 17 Nov 2008, Guenter Milde wrote:
To: [email protected]
From: Guenter Milde [EMAIL PROTECTED]
Subject: Re: Open a New Window in read-only mode?
Keith Roberts [EMAIL PROTECTED] schrieb:
Is it possible to open a new window in read-only mode, on a
lyx file that is r/w please?
I want to refer to previous sections of a document in
read-only mode in a new window, so I can keep a consistent
format for new sections written later in the same document.
I do not know of a straightforward way to achieve this.
Depending on what exactly you intend, there are two ways that spring to my
mind:
a) ViewPDF (or ViewPS): the output is read-only of course.
b) open the file in a second lyx process, started as a different user with
Günter
### Re: Open a New Window in read-only mode?
Thanks Paul. That sounds feasable. I did edit the document
in both windows! Maybe there could be an option in
preferences to set the second or more window(s) to read-only
mode? That will stop anyone from accidently editing the
document in the other opened windows.
Keith
On Mon, 17 Nov 2008, Paul A. Rubin wrote:
To: [email protected]
From: Paul A. Rubin [EMAIL PROTECTED]
Subject: Re: Open a New Window in read-only mode?
Keith Roberts wrote:
Is it possible to open a new window in read-only mode, on a lyx file
I want to refer to previous sections of a document in read-only mode in
a new window, so I can keep a consistent format for new sections
written later in the same document.
TIA
Keith Roberts
With LyX 1.6.0, you can open the doc and then use View - Split View into
Left and Right Half (or View - Split View into Upper and Lower Half) to
get two views on the same document. AFAIK neither is read-only, but
hopefully you can restrain yourself from editing one of them. :-)
/Paul
### Re: Query on printing with 'screens'
Unknown wrote:
Every time I go in for a book, to be printed via offset, my printer
has a problem. He takes the PDF file and attempts to do crazy things
like importing it into Windows/Corel Draw, etc.
Hmm...
He says the photos won't print because they don't have a screen.
Can you (or he) be more precise what you mean with a screen (at least
I have never heard of it, and a quick Goolge search did not bring
anything up). Is it some printers' jargon, or a bad translation?
Anyhow, you could also try to give him a postscript file (created via
latex+dvips), or create the pdf from postscript with Acrobat's Distiller
(with the Prepress Profile), or with Ghostscript (also there you have
Zillions of options, for example to not compress the images).
Or, if you have only a few figures, do not include the figures in the
PDF (just leave white space), and let the printer set in the pictures in
his application.
HTH,
### Re: Query on printing with 'screens'
Unknown wrote:
He says the photos won't print because they don't have a screen.
Is it some printers' jargon, or a bad translation?
The first.
(But then, it is really the printer who should know how to do the color
separation.)
### Re: Steps towards a portable LyX installation on Windows
Thomas Steffen
[EMAIL PROTECTED] wrote in
message
That sounds interesting. I know that LyXLauncher does some magic, but
I was not able to figure out what it was. Is there any way to check
what LyXLauncher does to the environment?
Try Sandboxie http://www.sandboxie.com/
Hth
### Re: Configure Lyx, R, Sweave on OS X
On 14 Nov 2008, at 15:52, mikeandkatedunbar wrote:
On 14 Nov 2008, at 14:50, Philippe Grosjean wrote:
mikeandkatedunbar wrote:
I am trying to get up and running with Lyx and R, using Sweave
I have achieved this on my Windows XP PC at work with MikTex. Great.
HOWEVER On my Mac (OSX 10.4.7 with MacTex 2008 installed) I have
come up against a “brick wall”
Lyx 1.6 is installed and I can generate dvi files from simple
example .lyx files
R 2.8 is installed, I am up to the stage where R CMD Sweave
foo.Rnw works, as does Latex foo.tex
kpsewhich Sweave.sty confirms that Latex can find Sweave.sty
I have followed the instructions in
http://cran.r-project.org/contrib/extra/lyx/INSTALL
and copied files to the relevant locations into
\users\me\Library\Application Support\Lyx-1.6
And reconfigured / restarted Lyx
But whenever I open a test file such as
http://cran.r-project.org/contrib/extra/lyx/Sweave-test-1.lyx
I get the same old message
“The layout file requested by this document, literate-
article.layout, is not usable. This is probably because a LaTeX
class or style file required by it is not available. ”
This does not appear to be a problem with Sweave.sty (at least,
not directly). It is your literate-article.layout which cannot be
found, is corrupted, or is incompatible with the new LyX 1.6
version. Have you tried with LyX 1.5.7?
It seems like Lyx cannot find Sweave.sty, event though Latex can
find it.
I'm at my wits end, so any advice on how to troubleshoot this
would be very much appreciated. While I'm quite familiar with R,
Lyx is very new to me.
Regards
Mike
Best,
Philippe Grosjean
YES, I installed LyX 1.5.7, copied the layouts across and it works
fine. Thanks so much. I guess there could be a problem with Lyx
1.6.0 and the Lyx customisation files from Gregor Gorjanc, at least
on OS X - I didn't have the problems with 1.6.0 on Windows.
regards
Mike
Just to finally put an end to this, the problem was caused by how I'd
grabbed the layout files from cran. I had right clicked on them in
Safari and saved them to the desktop, then copied to the layouts
folder. This wasn't correct, I think I had effectively saved links to
the files on CRAN, not the files themselves. When I grabbed the
layout files by ftp, everything was working OK, both in lyx 1.5.7 and
1.6.0. Thanks once again for the advice.
Mike
### Re: Query on printing with 'screens'
2008/11/17 Konrad Hofbauer [EMAIL PROTECTED]:
Unknown wrote:
He says the photos won't print because they don't have a screen.
Is it some printers' jargon, or a bad translation?
The first.
(But then, it is really the printer who should know how to do the color
separation.)
I now understand :-) But it seems they use very archaic methods of
preparing for print. Normally rasterization process in separation or
bw printing is currently done automatically these days when film or
plate is prepared to photoset (I don't know proper term in English for
naświetlarka).
Such process you describe I remember from ages of old Ventura under
Windows 3.1, when every picture has to have LPI and raster angles
defined separately.
--
Manveru
jabber: [EMAIL PROTECTED]
gg: 1624001
http://www.manveru.pl
On Saturday 15 November 2008 20:05:03 Rex Dieter wrote:
Pending some polish to the update text, the push request will be
soonish. See:
Feedback welcome.
It should be noticed that if the feedback is positive those packages are the
same that will appear in the updates. So if you want to contribute to either
LyX and Fedora then test those packages.
Note that judging from the behaviour in F-10 (to be) and from the reports
regarding LyX 1.6.0 on this list it should just work, even so it would be nice
to have feedback from Fedora users.
The links that Rex left allow to retrieve the generated rpms and to leave a
comment regarding the package.
If you have any problems to test the packages please feel free to ask for
further details.
-- Rex
--
José Abílio
### Problem with pdf-view in Lyx 1.6.0
Hello,
I installed Lyx 1.6.0 now and - congratulations: it is really good.
But I have some problems with pdf-view, that I had not with Lyx 1.5.6.
I'm shure, someone can help me and tell me, what to do:
The view of the help-files intro.lyx and tutorial.lyx is ok.
Problem with help-file userguide.lyx:
on the first latex-running appears the latex-mistake-window:
LaTeX Error: File wasysym.sty' not found.
\usepackage
{makeidx}
*** (cannot \read from terminal in nonstop modes)
Problem with help-file extended.lyx:
on the first latex-running appears the latex-mistake-window:
..., tableposition=top]{caption}[2004/07/16]
*** (cannot \read from terminal in nonstop modes)
Problem with help-file embeddedobjects.lyx:
on the first latex-running appears the latex-mistake-window:
{\Pifont{psy}}
I wasn't able to read the size data for this font,
so I will ignore the font specification.
[Wizards can fix TFM files using TFtoPL/PLtoTF.]
You might try inserting a different font spec;
e.g., type I\fontsame font id=substitute font name'.
..., tableposition=top]{caption}[2004/07/16]
*** (cannot \read from terminal in nonstop modes)
I don't know, whether there are other problems with other lyx-files.
Might be an incomplete lyx-installation the reason for this? Or what
could it be?
--
Mit freundlichen Grüßen
Matthias Schmidt
mailto:[EMAIL PROTECTED]
Diese Nachricht ist mit Norton Internet Security geprüft
___
Der frühe Vogel fängt den Wurm. Hier gelangen Sie zum neuen Yahoo! Mail:
http://mail.yahoo.de
### Re: Steps towards a portable LyX installation on Windows
Thomas Steffen wrote:
The other issue was that convert would not recognise ghostscript. I
read that @PSdelegate@ in delegates.xml relies on registry keys, and
indeed replacing it with gswin32c.exe solved the issue. This was
necessary to get previews working for eps files.
The build-in ImageMagick does not rely on registry keys but uses the
environment variables set by LyXLauncher (see the source for details) to
get the location of the Ghostscript directories. Note that not only
@PSdelegate@ is relevant but also the font directory etc.
Joost
### Re: lyx2lyx script broken (1.6.0 on Vista)
Andre Poenitz [EMAIL PROTECTED] writes:
In fact that's actually the most sensible behaviour since there are only
very few cases where a new version indeed can replace an older one
without any existing or imagined problem.
What's wrong with static linking? At least it goes away when the
application goes away.
JMarc
### Re: avoiding indentation within footnotes and adding vertical space under headings
Thanks. I found a simple way to add extra space after
insert vertical space (protected) command.
Regarding the footnotes I tried
\usepackage[para]{footmisc} and \usepackage[hang,
flushmargin]{footmisc}
both failed with lyx 1.6. but works fine with lyx 1.5.6.
The problem is that
lyx 1.5.6 don't want to open files created with lyx
1.6.
Excuse me. I must to say \usepackage[flushmargin]{footmisc} instead
\usepackage[para]{footmisc}
Currently I have this in my preamble in a work fine with lyx 1.6.0 and no have
any problem.
I installed lyx 1.5.7 and I can open files created with lyx 1.6.0.
I think that you have a specific problem in your computer.
Regards
Marcelo
Yahoo! Cocina
Recetas prácticas y comida saludable
http://ar.mujer.yahoo.com/cocina/
### Re: Print list of notes
Nick Bell wrote:
Charles de Miramon wrote:
Nick Bell wrote:
Is there anyway in which I can print a list of notes, preferably with
page references?
What kind of notes ? footnotes, endnotes, to-do notes
Lyx Notes
Note, there's no simple way. But if you switch them all to comments,
then they get output as \begin{comment}...\end{comment}, and then you
can arrange to print them as you like.
rh
### Re: Print list of notes
rgheck wrote:
Nick Bell wrote:
Charles de Miramon wrote:
Nick Bell wrote:
Is there anyway in which I can print a list of notes, preferably with
page references?
What kind of notes ? footnotes, endnotes, to-do notes
Lyx Notes
Note, there's no simple way. But if you switch them all to comments,
then they get output as \begin{comment}...\end{comment}, and then you
can arrange to print them as you like.
Oh, and to do that, you can use this command:
notes-mutate Note Comment
in the minibuffer.
rh
### Re: Print list of notes
rgheck wrote:
rgheck wrote:
Nick Bell wrote:
Charles de Miramon wrote:
Nick Bell wrote:
Is there anyway in which I can print a list of notes, preferably with
page references?
What kind of notes ? footnotes, endnotes, to-do notes
Lyx Notes
Note, there's no simple way. But if you switch them all to comments,
then they get output as \begin{comment}...\end{comment}, and then you
can arrange to print them as you like.
Oh, and to do that, you can use this command:
notes-mutate Note Comment
in the minibuffer.
rh
Thanks for that, but how do I print a list of comments? Nick
### Re: Problem with pdf-view in Lyx 1.6.0
Matthias Schmidt wrote:
Hello,
I installed Lyx 1.6.0 now and - congratulations: it is really good.
But I have some problems with pdf-view, that I had not with Lyx 1.5.6.
I'm shure, someone can help me and tell me, what to do:
The view of the help-files intro.lyx and tutorial.lyx is ok.
Problem with help-file userguide.lyx:
on the first latex-running appears the latex-mistake-window:
LaTeX Error: File wasysym.sty' not found.
Under Mandriva, wasysym.sty is in /usr/share/texmf/tex/latex/wasysm
Perhaps you also need to clickon the Use AMS maths... package under
I hope this helps.
\usepackage
{makeidx}
*** (cannot \read from terminal in nonstop modes)
Problem with help-file extended.lyx:
on the first latex-running appears the latex-mistake-window:
..., tableposition=top]{caption}[2004/07/16]
*** (cannot \read from terminal in nonstop modes)
Problem with help-file embeddedobjects.lyx:
on the first latex-running appears the latex-mistake-window:
{\Pifont{psy}}
I wasn't able to read the size data for this font,
so I will ignore the font specification.
[Wizards can fix TFM files using TFtoPL/PLtoTF.]
You might try inserting a different font spec;
e.g., type I\fontsame font id=substitute font name'.
..., tableposition=top]{caption}[2004/07/16]
*** (cannot \read from terminal in nonstop modes)
I don't know, whether there are other problems with other lyx-files.
Might be an incomplete lyx-installation the reason for this? Or what
could it be?
Yes it could be since 1.6.0 has just been released. If you are new to
Lyx I'd wait and see if anyone else has the same problem.
I'm using an earlier version of Lyx.
Regards, Donald
### Re: Lyx 1.6 on ubuntu 8.04
On Mon, 2008-11-17 at 17:56 +, Graham Smith wrote:
Has anyone installed 1.6 on Ubuntu 8.04? Its available for Jaunty (as
pointed out elsewhere on this forum), but not sure of the risks that may
be involved.
Yes I did successfully install 1.6 from source. I just follow from this
http://www.mail-archive.com/[email protected]/msg65444.html
I currently have 1.5.5 installed via the Ubuntu repository, should I
uninstall this before installing 1.6, or is it a bad idea to install 1.6
before its officially available for 8.04.
No i did not uninstall the version 1.5.5 as I am still using it for a
reason. It works parallel with version 1.6
./configure --with-version-suffix=-1.6.0
make
sudo make install
I am new to Linux, and still finding my feet with it.
Graham
### Re: Lyx 1.6 on ubuntu 8.04
Waluyo
On Mon, 2008-11-17 at 17:56 +, Graham Smith wrote:
Has anyone installed 1.6 on Ubuntu 8.04? Its available for Jaunty (as
pointed out elsewhere on this forum), but not sure of the risks that may
be involved.
Yes I did successfully install 1.6 from source. I just follow from this
http://www.mail-archive.com/[email protected]/msg65444.html
Thanks, that is really useful.
Graham
### can't use in hebrew under lyx
When I use the (quote) in hebrew under lyx I get the following error:
LaTeX Error: Command \textquotedbl unavailable in encoding LHE.
I have to change language to english in order to insert the symbol.
Is there a problem with my setup or is this a problem with lyx?
Thanks
### Re: \bind-files (Mac, 1.6)
Nick Bell wrote:
To try to put them back I put
\bind-file mac
Err that's the problem - it should be \bind_file mac not \bind-file mac.
~Nick
### Change names of TOC? Bibliography?
Does anyone know how to change the name of this section? In Lyx
report(koma-script) it prints out by default as Contents. Can I make it
Also, can I change the default name of the Bibliography as well?
I tried adding the following to the preamble, but it doesn't seem to have
an effect:
\renewcommand{\bibname}{List of References}
I am using the 'bibtotoc' option in the arguments to the document class.
What's the difference between this and using the following ERT TEX code?
With the hyperref package, the bibliography is hyperlinked to the TOC entry,
but if I use the bookmarks menu on the left in Acrobat, clicking on
Bibliography takes me to the title page of my document instead!
Alex
### Re: Lyx 1.6.0: icons on toolbar
- Mail Original -
De: alain didierjean [EMAIL PROTECTED]
À: lyx-users [email protected]
Envoyé: Samedi 15 Novembre 2008 18:13:08 GMT +01:00 Amsterdam / Berlin /
Berne / Rome / Stockholm / Vienne
Objet: Lyx 1.6.0: icons on toolbar
I Just downloaded the gentto package for lyx 1.6.0 : it compliles OK and
seems nice, but display toolbars with text (in french), not icons. It's
almost unusable. How do I get the icons back ? a utility ? a complie option ?
I fi go back to v.1.5.6, I get the icons all right...
SOLVED by emerge --update --newuse --deep --resume world
I'll never know what was wrong...
--
### Re: LyX 1.6.0. breaks down all the time
Benno Bühler wrote:
Hi,
I just changed from LyX 1.5.6 to 1.6.0 and I really like the new features of
the program…but: Somehow LyX crashes all the time. For example when I am
opening MS Outlook?!?
Yep, this has happened to me with all beta/RC versions too (for me, it
was more excel, but I could trigger it with other soft as well).
Unfortunately, there is no easy reproducible way to reproduce it on
demand...
Maybe it has to do something with the installer? Previously, I used the
alternative installer, to install LyX 1.6.0. (Windows XP) I used the
standard installer.
No, as I wrote above, I had this bug with all RC and betas, which were
the alternative installers. This bug seems to be affecting both build
families...
How can I access the log-file of the crashes? There pops up a window of LyX,
saying that I found a bug. But I cannot fully read or copy/paste the text.
IIRC, Windows XP saves them somewhere in your Local Settings\Temp
directory. Or somewhere around.
Best regards,
Olivier.
PS:
This bug was reported on devel-ML by Edwin Leuven under the title
lyx rc3 crashing all the time.
I also mentioned it here on October 24th in a thread about RC4 on the
user list.
Regards
Benno
### Change names of TOC? Bibliography?
Does anyone know how to change the name of this section? In Lyx
report(koma-script) it prints out by default as Contents. Can I make it
Also, to change the default name of the Bibliography I tried adding the
following to the preamble, but it doesn't seem to have an effect:
\renewcommand{\bibname}{List of References}
If I add this as ERT code right before the Bibliography in my LyX document,
the name is now changed in the PDF output. How come?
Also, I noticed how when compiling my LyX document oftentimes only one Latex
run is completed instead of two! In these cases, although I have the 'intoc'
option for my document, the Nomenclature does not appear in the TOC, although
I can see the entry when opening the .toc file manually.
Another funny thing, the same times when the Nomenclature doesn't appear in
the contents, the compiled PDF file also doesn't open automatically as it
should after being created. Instead, I have to look for it in the temp
directory and open it manually !!!
I am using the 'bibtotoc' option in the arguments to the document class.
(The bibliography appears in the Contents, even when the nomenclature doesn't!)
What's the difference between this and using the following ERT TEX code?
With the hyperref package, the bibliography is hyperlinked to the TOC entry,
but if I use the bookmarks menu on the left in Acrobat, clicking on
Bibliography takes me to the title page of my document instead!
Alex
### Re: LyX 1.6.0. breaks down all the time
Olivier Ripoll [EMAIL PROTECTED] writes:
Yep, this has happened to me with all beta/RC versions too (for me, it
was more excel, but I could trigger it with other soft as well).
Unfortunately, there is no easy reproducible way to reproduce it on
demand...
It would be nice to obtain a backtrace for that, but I do not know how
to do that in windows. The two causes I can think of are:
- clipboard: LyX hold the clipboard, and it loses it when another
application launches
- a focus problem
JMarc
### Re: \bind-files (Mac, 1.6)
Nick Bell [EMAIL PROTECTED] writes:
To try to put them back I put
\bind-file mac
It is \bind_file.
But it is easier to use the new shortcut editor, I guess.
JMarc
### Re: LyX 1.6.0. breaks down all the time
Olivier Ripoll [EMAIL PROTECTED] writes:
Benno Bühler wrote:
How can I access the log-file of the crashes? There pops up a window of LyX,
saying that I found a bug. But I cannot fully read or copy/paste the text.
IIRC, Windows XP saves them somewhere in your Local Settings\Temp
directory. Or somewhere around.
To copy/paste the log of the crash from the window saying you found a bug
(though I don't know how helpful that text is), you need to right-click in that
window and you can then Copy to Clipboard.
Go to a text editor and paste the contents!
Alex
### Re: LyX 1.6.0. breaks down all the time
Jean-Marc Lasgouttes wrote:
Olivier Ripoll [EMAIL PROTECTED] writes:
Yep, this has happened to me with all beta/RC versions too (for me, it
was more excel, but I could trigger it with other soft as well).
Unfortunately, there is no easy reproducible way to reproduce it on
demand...
It would be nice to obtain a backtrace for that, but I do not know how
to do that in windows. The two causes I can think of are:
- clipboard: LyX hold the clipboard, and it loses it when another
application launches
Bingo!
100% reproducible crash (3 out of 3) if I start excel after having
copied something in LyX.
100% no-crash if (2 out of 2) if I open excel with LyX open and have yet
not copied anything in LyX.
100% no-crash (2 out of 2) if I copy something in LyX, then copy
something in another application, then start excel. That's a nice
workaround for the short term.
I also explains why I was only seeing this bug in long sessions of LyX,
not in short ones (when trying to have a reproducible pattern for bugzilla).
PS: Yes, 7 tests is not very good statistically, but I guess that is
enough).
- a focus problem
JMarc
Should I open a bugzilla report or are you doing it?
Many thanks and best regards,
Olivier
### Print list of notes
Dear all,
Is there anyway in which I can print a list of notes, preferably with
page references?
Many thanks
~Nick
### Open a New Window in read-only mode?
Is it possible to open a new window in read-only mode, on a
lyx file that is r/w please?
I want to refer to previous sections of a document in
read-only mode in a new window, so I can keep a consistent
format for new sections written later in the same document.
TIA
Keith Roberts
-
Websites:
http://www.php-debuggers.net
http://www.karsites.net
Where will you spend Eternity?
http://www.fellowshiptractleague.org/tracts/images/PDF/tract_130.pdf
All email addresses are challenge-response protected with
TMDA [http://tmda.net]
-
### TOC in fullscreen
When entering full screen mode I sometimes get the table of contents
panel on the right. It is sporadic.
Anyone experience this?
### Re: TOC in fullscreen
Ivan Werning wrote:
panel on the right. It is sporadic.
Anyone experience this?
Yes, on my Mac. Haven't seen it on Windows.
~Nick
### Re: Print list of notes
Nick Bell wrote:
Dear all,
Is there anyway in which I can print a list of notes, preferably with
page references?
Many thanks
~Nick
What kind of notes ? footnotes, endnotes, to-do notes
Cheers,
Charles
--
http://www.kde-france.org
### re: Change names of TOC? Bibliography?
Does anyone know how to change the name of this section? In Lyx
report(koma-script) it prints out by default as Contents. Can I make it
yes
Also, to change the default name of the Bibliography I tried adding the
following to the preamble, but it doesn't seem to have an effect:
\renewcommand{\bibname}{List of References}
If I add this as ERT code right before the Bibliography in my LyX document,
the name is now changed in the PDF output. How come?
use this \renewcommand*{\bibname}{List of References}
I am using the 'bibtotoc' option in the arguments to the document class.
(The bibliography appears in the Contents, even when the nomenclature doesn't!)
What's the difference between this and using the following ERT TEX code?
if you just care for the bib to show up in the TOC, its the same; if you are
depending on other things like hyperref it will lead to different outcomes
With the hyperref package, the bibliography is hyperlinked to the TOC entry,
but if I use the bookmarks menu on the left in Acrobat, clicking on
Bibliography takes me to the title page of my document instead!
it should work, either you check your preferences or you could workaround with
setting up a hypertarget around your bibliography like this:
\hypertarget{YOURLABELNAME}{}
\pdfbookmark[0]{Bookmarkname}{YOURLABELNAME}
but then you will probably have to replace your bibtotoc option with KOMA by
Alex
cheers,
peerlynt
Pt! Schon vom neuen WEB.DE MultiMessenger gehört?
Der kanns mit allen: http://www.produkte.web.de/messenger/?did=3123
### Re: lyx2lyx script broken (1.6.0 on Vista)
Uwe Stöhr wrote:
Dominik Waßenhoven schrieb:
On the Vista machine, I had no Python installed and the lyx2lyx script
failed. I now installed Microsoft's VC++ redistributable package, as
suggested by Paul Rubin, and now the lyx2lyx script works. So I think
there is a problem with the python.exe and/or python26.dll which are in
the bin directory of LyX 1.6.
But I also had no Python installed on this Vista machine, only installed
LyX using my installer and it worked. I also got feedback that it works
for others too.
It appears the bundled Python requires a particular release of
Microsoft's C runtime. There are approximately a zillion releases of
the MSVC runtime, all mutually incompatible.
For years, Microsoft handled this by changing the name of the MSVC
runtime DLLs with each release. More recently, when someone decided
it'd be good to have more incompatible runtime versions than would fit
in a single MSVC release cycle, they invented the Side by Side
versioning method, which has the advantages of being a black box,
completely different from previous Windows DLL versioning mechanisms,
and entirely mysterious, opaque, and frustrating for users.
Side-by-Side sticks various releases of the MSVC runtime in
directories under %windir%\winsxs.
Product installers are supposed to include the MSVC redistributable
package for the particular MSVC version they need, which will get
installed in Side-by-Side if it's not already present.
Probably, people who don't have problems with the minimal Python
included with Uwe's installer already have the necessary MSVC
redistributable on their machine from some other product installation.
The fix would be to include the appropriate MSVC redistributable in
Uwe's LyX installer. Note that it may have to be updated any time the
Python binaries are updated, since they might be linked with a
different MSVC version.
Sure makes SVR4 shared object versioning look good, doesn't it?
--
Michael Wojcik
Micro Focus
Rhetoric Writing, Michigan State University
### Steps towards a portable LyX installation on Windows
Hi All
I made quite good progress producing a portable LyX installation based
on LyX 1.6.0. What would be the best place to post the instructions?
I think wiki.lyx.org may be suitable, but it looks a bit disorganised
at the moment, and it seems that only developers have access anyway
(?).
I used texlive 2008 as my tex installation, which already provides
some portability. I follow the same basic approach as tl-portable.bat,
but add the necessary environment variables for LyX, convert and
ghostscript. Apart from one problem between the bundled convert and
the bundled ghoscript, this works really well.
Regards,
Thomas
### Re: Open a New Window in read-only mode?
Keith Roberts [EMAIL PROTECTED] schrieb:
Is it possible to open a new window in read-only mode, on a
lyx file that is r/w please?
I want to refer to previous sections of a document in
read-only mode in a new window, so I can keep a consistent
format for new sections written later in the same document.
I do not know of a straightforward way to achieve this.
Depending on what exactly you intend, there are two ways that spring to my
mind:
a) ViewPDF (or ViewPS): the output is read-only of course.
b) open the file in a second lyx process, started as a different user with
Günter
### Re: Idiot's guide to creating a new style - or inset?
Steve Litt wrote:
On Sunday 16 November 2008 03:43:04 pm rgheck wrote:
Yes, that's what you need. Try something like this:
#\DeclareLyXModule{TextSuperSub}
#DescriptionBegin
#\theendnotes in ERT where you want the endnotes to appear.
#DescriptionEnd
Format 11
InsetLayout Custom:Superscript
LyXTypecustom
LatexNametextsuperscript
LatexTypecommand
Decoration classic
Font
SizeSmall
EndFont
MultiPar false
LabelStringsuper
End
and something similar for subscripts. Save it to textsupersub.module in
your LyX layouts directory and reconfigure. You can tweak it as you wish.
Hi Richard,
What's the difference bettween InsetLayout, CharacterStyle and Environment?
When would you use InsetLayout over one of the others?
InsetLayout is new in 1.6. It incorporates the old charstyle (LyXType
charstyle) and also these new custom insets, which look like footnotes
but do anything you like. Of course, textsuperscript could (and probably
should) be a charstyle.
What is the Decoration LyX property (set to classic in your example)?
This makes the inset look like a footnote: with a little button. There
are other choices, too: minimalistic (no button) and, uh, can't remember.
rh
### Re: Idiot's guide to creating a new style - or inset?
Nick Bell wrote:
rgheck wrote:
#\DeclareLyXModule{TextSuperSub}
#DescriptionBegin
#\theendnotes in ERT where you want the endnotes to appear.
#DescriptionEnd
Format 11
InsetLayout Custom:Superscript
LyXTypecustom
LatexNametextsuperscript
LatexTypecommand
Decoration classic
Font
SizeSmall
EndFont
MultiPar false
LabelStringsuper
End
That works brilliantly, thanks. Now how do I get the inset label to be
equal to the parameter (e.g. XYZ in \textsuperscript{XYZ})? Or should
I be using a user defined char style (??) ?
The label can't be modified. You could try a charstyle. You could also
try Decoration minimalistic.
rh
~Nick
### Re: LyX 1.6.0. breaks down all the time
I can reproduce the recipe from Olivier. I had reported that in this bug entry:
http://bugzilla.lyx.org/show_bug.cgi?id=5472
Still I do not know if we can call this a bug or a nice anti-Microsoft feature
:-D
Cheers,
Nicolás
Alex wrote:
Olivier Ripoll [EMAIL PROTECTED] writes:
Benno Bühler wrote:
How can I access the log-file of the crashes? There pops up a window of LyX,
saying that I found a bug. But I cannot fully read or copy/paste the text.
IIRC, Windows XP saves them somewhere in your Local Settings\Temp
directory. Or somewhere around.
To copy/paste the log of the crash from the window saying you found a bug
(though I don't know how helpful that text is), you need to right-click in that
window and you can then Copy to Clipboard.
Go to a text editor and paste the contents!
Alex
### Re: Steps towards a portable LyX installation on Windows
Thomas Steffen wrote:
I used texlive 2008 as my tex installation, which already provides
some portability. I follow the same basic approach as tl-portable.bat,
but add the necessary environment variables for LyX, convert and
ghostscript. Apart from one problem between the bundled convert and
the bundled ghoscript, this works really well.
The standard installer already bundles Ghostscript and ImageMagick in a
portable way (no registry keys need to be modified).
Joost
### Re: lyx2lyx script broken (1.6.0 on Vista)
Michael Wojcik wrote:
Uwe Stöhr wrote:
Dominik Waßenhoven schrieb:
On the Vista machine, I had no Python installed and the lyx2lyx script
failed. I now installed Microsoft's VC++ redistributable package, as
suggested by Paul Rubin, and now the lyx2lyx script works. So I think
there is a problem with the python.exe and/or python26.dll which are in
the bin directory of LyX 1.6.
But I also had no Python installed on this Vista machine, only installed
LyX using my installer and it worked. I also got feedback that it works
for others too.
It appears the bundled Python requires a particular release of
Microsoft's C runtime. There are approximately a zillion releases of
the MSVC runtime, all mutually incompatible.
For years, Microsoft handled this by changing the name of the MSVC
runtime DLLs with each release. More recently, when someone decided
it'd be good to have more incompatible runtime versions than would fit
in a single MSVC release cycle, they invented the Side by Side
versioning method, which has the advantages of being a black box,
completely different from previous Windows DLL versioning mechanisms,
and entirely mysterious, opaque, and frustrating for users.
Side-by-Side sticks various releases of the MSVC runtime in
directories under %windir%\winsxs.
Product installers are supposed to include the MSVC redistributable
package for the particular MSVC version they need, which will get
installed in Side-by-Side if it's not already present.
Probably, people who don't have problems with the minimal Python
included with Uwe's installer already have the necessary MSVC
redistributable on their machine from some other product installation.
The fix would be to include the appropriate MSVC redistributable in
Uwe's LyX installer. Note that it may have to be updated any time the
Python binaries are updated, since they might be linked with a
different MSVC version.
Sure makes SVR4 shared object versioning look good, doesn't it?
I wonder if disk manufacturers are paying M$to do this? I've got about 54MB of crap in %windir%\winsxs, with multiple versions of each set of files. Presumably there's no way for Windoze to know that something depending on an older version can use the newer version, so old versions never go away. Kind of like that half gigabyte (and counting) of patch files that never gets deleted. ### Re: Open a New Window in read-only mode? Keith Roberts wrote: Is it possible to open a new window in read-only mode, on a lyx file that is r/w please? I want to refer to previous sections of a document in read-only mode in a new window, so I can keep a consistent format for new sections written later in the same document. TIA Keith Roberts With LyX 1.6.0, you can open the doc and then use View - Split View into Left and Right Half (or View - Split View into Upper and Lower Half) to get two views on the same document. AFAIK neither is read-only, but hopefully you can restrain yourself from editing one of them. :-) /Paul ### Re: Steps towards a portable LyX installation on Windows On Mon, Nov 17, 2008 at 4:03 PM, Joost Verburg [EMAIL PROTECTED] wrote: The standard installer already bundles Ghostscript and ImageMagick in a portable way (no registry keys need to be modified). That sounds interesting. I know that LyXLauncher does some magic, but I was not able to figure out what it was. Is there any way to check what LyXLauncher does to the environment? Anyway, I have managed to put my experience down in the Wiki at http://wiki.lyx.org/Windows/PortableInstallation . It is certainly not easy or painless, but I think a few small changes could improve the process significantly. Maybe the issues I had are bugs? The first problem I had was related to the path. Ghostscript was not really happy, and for some reason convert would not find ghostscript. I had to do the following changes to get previews and eps-pdf conversion working (the first three lines may or may not be necessary, I did not test them individually): path %LYX_DIR%python;%path% path %LYX_DIR%bin;%path% path %LYX_DIR%imagemagick;%path% set GS_DIR=%LYX_DIR%ghostscript\ path %GS_DIR%bin;%path% set GS_LIB=%GS_DIR%lib;%GS_DIR%fonts;%GS_DIR%Resource The other issue was that convert would not recognise ghostscript. I read that @PSdelegate@ in delegates.xml relies on registry keys, and indeed replacing it with gswin32c.exe solved the issue. This was necessary to get previews working for eps files. Finally I keep getting an error message from reconfigure about chklatex.ltx, which caused by the platex check. It seems like the PLATEX variable is empty, and it calls the argument instead if cmdOutput(PLATEX + ' chklatex.ltx').find('pLaTeX2e') != -1: which is not recognised as an executable or an association. And then there is a problem with TeX Live 2008. The new portable function tl-portable.bat is very nice, but unfortunately it is so inflexible that it can only start a console, and not another program. Changing this may be easy, but it would require some advanced batch language tricks, which is not my specialty. Regards, Thomas ### Re: lyx2lyx script broken (1.6.0 on Vista) On Mon, Nov 17, 2008 at 11:07:05AM -0500, Paul A. Rubin wrote: I wonder if disk manufacturers are paying M$ to do this? I've got about
54MB of crap in %windir%\winsxs, with multiple versions of each set of
files. Presumably there's no way for Windoze to know that something
depending on an older version can use the newer version, so old versions
never go away.
In fact that's actually the most sensible behaviour since there are only
very few cases where a new version indeed can replace an older one
without any existing or imagined problem. In particular that would mean
not only source and binary but also behavioural compatibility including
keeping buggy behaviour. When you factor in that application also can
depend on runtime characteristics even optimizations might have to be
ruled out, so there's really not much left what could be done in a newer
version...
Andre'
### Re: Print list of notes
Charles de Miramon wrote:
Nick Bell wrote:
Is there anyway in which I can print a list of notes, preferably with
page references?
What kind of notes ? footnotes, endnotes, to-do notes
Lyx Notes
Thanks
Nick
### hfill
Hello,
Where is the hfill insert in lyx 1.6 ?
My binding doesn't work anymore !
Philippe Camus
### Re: Idiot's guide to creating a new style - or inset?
Richard Heck wrote the following on 17/11/2008:
The label can't be modified. You could try a charstyle. You could
also try Decoration minimalistic.
Charstyle works well, but I suppose I can't set the style of the
displayed label to super/subscript can I? (That would probably be a bit
WYSIWYG).
I've got more or less what I want with $_{\text{XYZ}}$ command sequences
bound to keys.
Thanks, Nick
### Re: hfill
[EMAIL PROTECTED] wrote:
Where is the hfill insert in lyx 1.6 ?
Insert Formatting Horizontal space
My binding doesn't work anymore !
space-insert hfill
Regards,
Dominik.-
### Query on printing with 'screens'
Hi all:
I'm a Lyx user in Goa, and hope you won't mind me intruding.
Every time I go in for a book, to be printed via offset, my printer
has a problem. He takes the PDF file and attempts to do crazy things
like importing it into Windows/Corel Draw, etc.
He says the photos won't print because they don't have a screen.
Query:
* Is he right?
* Is there some way of putting a screen on the photos? LyX takes TeX
commands, so maybe if there's one I could use it.
Earlier, he was struggling to find how to print the file laterally
inverted (mirror image), and we found the command after some search.
Best, FN
PS: A cc'd reply to me would be highly appreciated...
--
FN * Independent Journalist http://fn.goa-india.org
Blog: http://fredericknoronha.wordpress.com
M: +91-9822122436 P: +91-832-2409490
### Lyx 1.6 on ubuntu 8.04
Has anyone installed 1.6 on Ubuntu 8.04? Its available for Jaunty (as
pointed out elsewhere on this forum), but not sure of the risks that may
be involved.
I currently have 1.5.5 installed via the Ubuntu repository, should I
uninstall this before installing 1.6, or is it a bad idea to install 1.6
before its officially available for 8.04.
I am new to Linux, and still finding my feet with it.
Graham
### Re: Open a New Window in read-only mode?
Thanks Guenter. I want to view the lyx source code itself,
so I can use that as a pattern for more sections.
Keith
On Mon, 17 Nov 2008, Guenter Milde wrote:
To: [email protected]
From: Guenter Milde [EMAIL PROTECTED]
Subject: Re: Open a New Window in read-only mode?
Keith Roberts [EMAIL PROTECTED] schrieb:
Is it possible to open a new window in read-only mode, on a
lyx file that is r/w please?
I want to refer to previous sections of a document in
read-only mode in a new window, so I can keep a consistent
format for new sections written later in the same document.
I do not know of a straightforward way to achieve this.
Depending on what exactly you intend, there are two ways that spring to my
mind:
a) ViewPDF (or ViewPS): the output is read-only of course.
b) open the file in a second lyx process, started as a different user with
Günter
### Re: Open a New Window in read-only mode?
Thanks Paul. That sounds feasable. I did edit the document
in both windows! Maybe there could be an option in
preferences to set the second or more window(s) to read-only
mode? That will stop anyone from accidently editing the
document in the other opened windows.
Keith
On Mon, 17 Nov 2008, Paul A. Rubin wrote:
To: [email protected]
From: Paul A. Rubin [EMAIL PROTECTED]
Subject: Re: Open a New Window in read-only mode?
Keith Roberts wrote:
Is it possible to open a new window in read-only mode, on a lyx file
I want to refer to previous sections of a document in read-only mode in
a new window, so I can keep a consistent format for new sections
written later in the same document.
TIA
Keith Roberts
With LyX 1.6.0, you can open the doc and then use View - Split View into
Left and Right Half (or View - Split View into Upper and Lower Half) to
get two views on the same document. AFAIK neither is read-only, but
hopefully you can restrain yourself from editing one of them. :-)
/Paul
### Re: Query on printing with 'screens'
Unknown wrote:
Every time I go in for a book, to be printed via offset, my printer
has a problem. He takes the PDF file and attempts to do crazy things
like importing it into Windows/Corel Draw, etc.
Hmm...
He says the photos won't print because they don't have a screen.
Can you (or he) be more precise what you mean with a screen (at least
I have never heard of it, and a quick Goolge search did not bring
anything up). Is it some printers' jargon, or a bad translation?
Anyhow, you could also try to give him a postscript file (created via
latex+dvips), or create the pdf from postscript with Acrobat's Distiller
(with the Prepress Profile), or with Ghostscript (also there you have
Zillions of options, for example to not compress the images).
Or, if you have only a few figures, do not include the figures in the
PDF (just leave white space), and let the printer set in the pictures in
his application.
HTH,
### Re: Query on printing with 'screens'
Unknown wrote:
He says the photos won't print because they don't have a screen.
Is it some printers' jargon, or a bad translation?
The first.
(But then, it is really the printer who should know how to do the color
separation.)
### Re: Steps towards a portable LyX installation on Windows
Thomas Steffen
[EMAIL PROTECTED] wrote in
message
That sounds interesting. I know that LyXLauncher does some magic, but
I was not able to figure out what it was. Is there any way to check
what LyXLauncher does to the environment?
Try Sandboxie http://www.sandboxie.com/
Hth
### Re: Configure Lyx, R, Sweave on OS X
On 14 Nov 2008, at 15:52, mikeandkatedunbar wrote:
On 14 Nov 2008, at 14:50, Philippe Grosjean wrote:
mikeandkatedunbar wrote:
I am trying to get up and running with Lyx and R, using Sweave
I have achieved this on my Windows XP PC at work with MikTex. Great.
HOWEVER On my Mac (OSX 10.4.7 with MacTex 2008 installed) I have
come up against a “brick wall”
Lyx 1.6 is installed and I can generate dvi files from simple
example .lyx files
R 2.8 is installed, I am up to the stage where R CMD Sweave
foo.Rnw works, as does Latex foo.tex
kpsewhich Sweave.sty confirms that Latex can find Sweave.sty
I have followed the instructions in
http://cran.r-project.org/contrib/extra/lyx/INSTALL
and copied files to the relevant locations into
\users\me\Library\Application Support\Lyx-1.6
And reconfigured / restarted Lyx
But whenever I open a test file such as
http://cran.r-project.org/contrib/extra/lyx/Sweave-test-1.lyx
I get the same old message
“The layout file requested by this document, literate-
article.layout, is not usable. This is probably because a LaTeX
class or style file required by it is not available. ”
This does not appear to be a problem with Sweave.sty (at least,
not directly). It is your literate-article.layout which cannot be
found, is corrupted, or is incompatible with the new LyX 1.6
version. Have you tried with LyX 1.5.7?
It seems like Lyx cannot find Sweave.sty, event though Latex can
find it.
I'm at my wits end, so any advice on how to troubleshoot this
would be very much appreciated. While I'm quite familiar with R,
Lyx is very new to me.
Regards
Mike
Best,
Philippe Grosjean
YES, I installed LyX 1.5.7, copied the layouts across and it works
fine. Thanks so much. I guess there could be a problem with Lyx
1.6.0 and the Lyx customisation files from Gregor Gorjanc, at least
on OS X - I didn't have the problems with 1.6.0 on Windows.
regards
Mike
Just to finally put an end to this, the problem was caused by how I'd
grabbed the layout files from cran. I had right clicked on them in
Safari and saved them to the desktop, then copied to the layouts
folder. This wasn't correct, I think I had effectively saved links to
the files on CRAN, not the files themselves. When I grabbed the
layout files by ftp, everything was working OK, both in lyx 1.5.7 and
1.6.0. Thanks once again for the advice.
Mike
### Re: Query on printing with 'screens'
2008/11/17 Konrad Hofbauer [EMAIL PROTECTED]:
Unknown wrote:
He says the photos won't print because they don't have a screen.
Is it some printers' jargon, or a bad translation?
The first.
(But then, it is really the printer who should know how to do the color
separation.)
I now understand :-) But it seems they use very archaic methods of
preparing for print. Normally rasterization process in separation or
bw printing is currently done automatically these days when film or
plate is prepared to photoset (I don't know proper term in English for
naświetlarka).
Such process you describe I remember from ages of old Ventura under
Windows 3.1, when every picture has to have LPI and raster angles
defined separately.
--
Manveru
jabber: [EMAIL PROTECTED]
gg: 1624001
http://www.manveru.pl
On Saturday 15 November 2008 20:05:03 Rex Dieter wrote:
Pending some polish to the update text, the push request will be
soonish. See:
Feedback welcome.
It should be noticed that if the feedback is positive those packages are the
same that will appear in the updates. So if you want to contribute to either
LyX and Fedora then test those packages.
Note that judging from the behaviour in F-10 (to be) and from the reports
regarding LyX 1.6.0 on this list it should just work, even so it would be nice
to have feedback from Fedora users.
The links that Rex left allow to retrieve the generated rpms and to leave a
comment regarding the package.
If you have any problems to test the packages please feel free to ask for
further details.
-- Rex
--
José Abílio
### Problem with pdf-view in Lyx 1.6.0
Hello,
I installed Lyx 1.6.0 now and - congratulations: it is really good.
But I have some problems with pdf-view, that I had not with Lyx 1.5.6.
I'm shure, someone can help me and tell me, what to do:
The view of the help-files intro.lyx and tutorial.lyx is ok.
Problem with help-file userguide.lyx:
on the first latex-running appears the latex-mistake-window:
\usepackage
{makeidx}
*** (cannot \read from terminal in nonstop modes)
Problem with help-file extended.lyx:
on the first latex-running appears the latex-mistake-window:
LaTeX Error: File caption.sty' not found.
..., tableposition=top]{caption}[2004/07/16]
*** (cannot \read from terminal in nonstop modes)
Problem with help-file embeddedobjects.lyx:
on the first latex-running appears the latex-mistake-window:
{\Pifont{psy}}
I wasn't able to read the size data for this font,
so I will ignore the font specification.
[Wizards can fix TFM files using TFtoPL/PLtoTF.]
You might try inserting a different font spec;
e.g., type I\fontsame font id=substitute font name'.
2. LaTeX Error: File caption.sty' not found.
..., tableposition=top]{caption}[2004/07/16]
*** (cannot \read from terminal in nonstop modes)
I don't know, whether there are other problems with other lyx-files.
Might be an incomplete lyx-installation the reason for this? Or what
could it be?
--
Mit freundlichen Grüßen
Matthias Schmidt
mailto:[EMAIL PROTECTED]
Diese Nachricht ist mit Norton Internet Security geprüft
___
Der frühe Vogel fängt den Wurm. Hier gelangen Sie zum neuen Yahoo! Mail:
http://mail.yahoo.de
### Re: Steps towards a portable LyX installation on Windows
Thomas Steffen wrote:
The other issue was that convert would not recognise ghostscript. I
read that @PSdelegate@ in delegates.xml relies on registry keys, and
indeed replacing it with gswin32c.exe solved the issue. This was
necessary to get previews working for eps files.
The build-in ImageMagick does not rely on registry keys but uses the
environment variables set by LyXLauncher (see the source for details) to
get the location of the Ghostscript directories. Note that not only
@PSdelegate@ is relevant but also the font directory etc.
Joost
### Re: lyx2lyx script broken (1.6.0 on Vista)
Andre Poenitz [EMAIL PROTECTED] writes:
In fact that's actually the most sensible behaviour since there are only
very few cases where a new version indeed can replace an older one
without any existing or imagined problem.
What's wrong with static linking? At least it goes away when the
application goes away.
JMarc
### Re: avoiding indentation within footnotes and adding vertical space under headings
Thanks. I found a simple way to add extra space after
insert vertical space (protected) command.
Regarding the footnotes I tried
\usepackage[para]{footmisc} and \usepackage[hang,
flushmargin]{footmisc}
both failed with lyx 1.6. but works fine with lyx 1.5.6.
The problem is that
lyx 1.5.6 don't want to open files created with lyx
1.6.
Excuse me. I must to say \usepackage[flushmargin]{footmisc} instead
\usepackage[para]{footmisc}
Currently I have this in my preamble in a work fine with lyx 1.6.0 and no have
any problem.
I installed lyx 1.5.7 and I can open files created with lyx 1.6.0.
I think that you have a specific problem in your computer.
Regards
Marcelo
Yahoo! Cocina
Recetas prácticas y comida saludable
http://ar.mujer.yahoo.com/cocina/
### Re: Print list of notes
Nick Bell wrote:
Charles de Miramon wrote:
Nick Bell wrote:
Is there anyway in which I can print a list of notes, preferably with
page references?
What kind of notes ? footnotes, endnotes, to-do notes
Lyx Notes
Note, there's no simple way. But if you switch them all to comments,
then they get output as \begin{comment}...\end{comment}, and then you
can arrange to print them as you like.
rh
### Re: Print list of notes
rgheck wrote:
Nick Bell wrote:
Charles de Miramon wrote:
Nick Bell wrote:
Is there anyway in which I can print a list of notes, preferably with
page references?
What kind of notes ? footnotes, endnotes, to-do notes
Lyx Notes
Note, there's no simple way. But if you switch them all to comments,
then they get output as \begin{comment}...\end{comment}, and then you
can arrange to print them as you like.
Oh, and to do that, you can use this command:
notes-mutate Note Comment
in the minibuffer.
rh
### Re: Print list of notes
rgheck wrote:
rgheck wrote:
Nick Bell wrote:
Charles de Miramon wrote:
Nick Bell wrote:
Is there anyway in which I can print a list of notes, preferably with
page references?
What kind of notes ? footnotes, endnotes, to-do notes
Lyx Notes
Note, there's no simple way. But if you switch them all to comments,
then they get output as \begin{comment}...\end{comment}, and then you
can arrange to print them as you like.
Oh, and to do that, you can use this command:
notes-mutate Note Comment
in the minibuffer.
rh
Thanks for that, but how do I print a list of comments? Nick
### Re: Problem with pdf-view in Lyx 1.6.0
Matthias Schmidt wrote:
Hello,
I installed Lyx 1.6.0 now and - congratulations: it is really good.
But I have some problems with pdf-view, that I had not with Lyx 1.5.6.
I'm shure, someone can help me and tell me, what to do:
The view of the help-files intro.lyx and tutorial.lyx is ok.
Problem with help-file userguide.lyx:
on the first latex-running appears the latex-mistake-window:
Under Mandriva, wasysym.sty is in /usr/share/texmf/tex/latex/wasysm
Perhaps you also need to clickon the Use AMS maths... package under
I hope this helps.
\usepackage
{makeidx}
*** (cannot \read from terminal in nonstop modes)
Problem with help-file extended.lyx:
on the first latex-running appears the latex-mistake-window:
LaTeX Error: File caption.sty' not found.
..., tableposition=top]{caption}[2004/07/16]
*** (cannot \read from terminal in nonstop modes)
Problem with help-file embeddedobjects.lyx:
on the first latex-running appears the latex-mistake-window:
{\Pifont{psy}}
I wasn't able to read the size data for this font,
so I will ignore the font specification.
[Wizards can fix TFM files using TFtoPL/PLtoTF.]
You might try inserting a different font spec;
e.g., type I\fontsame font id=substitute font name'.
2. LaTeX Error: File caption.sty' not found.
..., tableposition=top]{caption}[2004/07/16]
*** (cannot \read from terminal in nonstop modes)
I don't know, whether there are other problems with other lyx-files.
Might be an incomplete lyx-installation the reason for this? Or what
could it be?
Yes it could be since 1.6.0 has just been released. If you are new to
Lyx I'd wait and see if anyone else has the same problem.
I'm using an earlier version of Lyx.
Regards, Donald
### Re: Lyx 1.6 on ubuntu 8.04
On Mon, 2008-11-17 at 17:56 +, Graham Smith wrote:
Has anyone installed 1.6 on Ubuntu 8.04? Its available for Jaunty (as
pointed out elsewhere on this forum), but not sure of the risks that may
be involved.
Yes I did successfully install 1.6 from source. I just follow from this
http://www.mail-archive.com/[email protected]/msg65444.html
I currently have 1.5.5 installed via the Ubuntu repository, should I
uninstall this before installing 1.6, or is it a bad idea to install 1.6
before its officially available for 8.04.
No i did not uninstall the version 1.5.5 as I am still using it for a
reason. It works parallel with version 1.6
./configure --with-version-suffix=-1.6.0
make
sudo make install
I am new to Linux, and still finding my feet with it.
|
{"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": 0.6394650340080261, "perplexity": 8038.258333737685}, "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-2021-25/segments/1623488539764.83/warc/CC-MAIN-20210623165014-20210623195014-00026.warc.gz"}
|
https://physics.aps.org/articles/v9/89
|
FOCUS
# A Thermostat that Consumes No Energy
Physics 9, 89
Experiments show that a region next to changing hot and cold areas can be maintained at a fixed temperature without consuming energy.
Maintaining stable temperatures is important in electronic chips and building interiors, and it usually requires energy for heating or cooling. Yet a group of Chinese physicists has now demonstrated how to control the temperature in a region surrounded by changing hot and cold areas without using additional energy. The idea is to enclose the region with materials whose thermal properties change with temperature. The team showed that, without consuming energy, the central region of a metallic strip stayed at a constant temperature despite heating one end by 30 degrees. The researchers believe their concept can be developed into an energy-saving system for practical use.
Keeping a fixed temperature inside a house with one side shaded and the other side exposed to both morning and noontime sun would normally require significant cooling energy. Similar temperature control problems, within devices with large temperature differences that change over time, also arise in electronics and aircraft engines.
To address such problems, Jiping Huang of Fudan University in Shanghai and his colleagues propose an energy-free thermostat. They imagine a small zone at temperature $T$ between two beams extending in opposite directions, one whose far end is cold, the other hot. The challenge is to prevent the central zone from heating or cooling as the temperatures of the far ends of the beams vary.
The team's scheme exploits the possibility that the heat conductivity of a material—a measure of how easily heat flows through it—can vary with the material's temperature. As they show mathematically, the cold beam material needs to be chosen so that it conducts heat well at temperatures above T and poorly at temperatures below T. The hot beam should have the opposite properties. Solving the heat flow equations, the team shows that the temperature within the central zone will then remain nearly constant at temperature T as the temperature of, say, the hot end is raised.
Huang and his colleagues require that the total rate of heat flow from hot to cold remain unchanged as the hot end warms, so no energy is added or removed. One might expect that as the hot side becomes hotter, the central region would also heat up. Instead, the hot beam's heat conductivity drops, which has the effect of increasing the temperature difference between the hot end and the central zone. As with electric wires or water pipes, when the resistance to flow through a channel increases, the difference in voltage or pressure across the channel also goes up, assuming the flow rate is fixed. For heat flow, the analogy implies an increased temperature difference, which in this case is just enough to maintain the central zone at temperature T.
The researchers also demonstrated the idea in an experiment, trying to keep a constant temperature in the central zone of a thin metallic strip with variable hot and cold temperatures applied to its ends. To make the conducting beams, they constructed composite structures using two layers built of interlocking lateral strips of different materials. One layer of strips was fixed in place and able to conduct heat weakly; the other layer of strips involved a material that bends upward when the temperature changes, breaking the conduction path and leaving only the lower-conductivity layer. In experiments using thermal imaging, the researchers found that when the temperature of the hot end was increased from 320 to 353 K, the temperature in the central zone went up by only 1 degree.
Huang expects the idea to find commercial uses quite soon, especially in efforts to reduce energy consumption. For home temperature control, for example, materials with the appropriate temperature-dependent conductivity applied to the exterior surfaces of homes could reduce the need for air conditioning. He suggests that the concept could also work for satellites—a spacecraft can develop huge temperature differences between its Sun-facing side and other parts of the craft.
"This idea is quite novel and sophisticated," says Cheng-Wei Qiu of the National University of Singapore. "It has great potential for real application in situations where the environmental temperatures on two sides of some object change," he says, adding that this approach for temperature regulation in homes is "quite promising."
This research is published in Physical Review Letters.
–Mark Buchanan
Mark Buchanan is a freelance science writer who splits his time between Abergavenny, UK, and Notre Dame de Courson, France.
## Related Articles
Condensed Matter Physics
### Seeking Supersolidity in Helium Layers
A scheme that proves the superfluidity of a layer of helium-4 on graphite holds promise for demonstrating that the layer may also be a supersolid. Read More »
Materials Science
### A Unifying View of Thin-Plate Fracture
A new theoretical framework simultaneously describes the bending and the fracturing of thin plates, offering a way to tackle complex cracking problems that involve both modes of mechanical deformation. Read More »
Materials Science
### The Geometry of Basket Weaving
Researchers teamed up with an artist to tweak a popular basket-weaving approach, finding a way to weave ribbons to produce any curvature desired. Read More »
|
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 1, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "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": 0.4708876609802246, "perplexity": 1044.3406888174673}, "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-2021-39/segments/1631780057303.94/warc/CC-MAIN-20210922011746-20210922041746-00423.warc.gz"}
|
http://pttk.org.pl/t3rybzr/how-to-find-concavity-intervals-06f068
|
finding intervals of increase and decrease, Graphs of curves can either be concave up or concave down, Concave up graphs open upward, and have the shape, Concave down graphs open downward, with the shape, To determine the concavity of a graph, find the second derivative of the given function and find the values that make it $0$ or undefined. Set the second derivative equal to zero and solve. The opposite of concave up graphs, concave down graphs point in the opposite direction. Else, if $f''(x)<0$, the graph is concave down on the interval. Evaluate the integral between $[0,x]$ for some function and then differentiate twice to find the concavity of the resulting function? Since the domain of $$f$$ is the union of three intervals, it makes sense that the concavity of $$f$$ could switch across intervals. Find the maximum, minimum, inflection points, and intervals of increasing/decreasing, and concavity of the function {eq}\displaystyle f (x) = x^4 - 4 x^3 + 10 {/eq}. 2. Determining concavity of intervals and finding points of inflection: algebraic. Locate the x-values at which f ''(x) = 0 or f ''(x) is undefined. In general, you can skip the multiplication sign, so 5 x is equivalent to 5 ⋅ x. To view the graph of this function, click here. Let us again consider graph A in Fig.- 22. To determine the intervals on which the graph of a continuous function is concave upward or downward we can apply the second derivative test. Therefore, there is an inflection point at $x=-2$. The perfect example of this is the graph of $y=sin(x)$. Solution: Since this is never zero, there are not points ofinflection. First, find the second derivative. This video explains how to find the open intervals for which a function is increasing or decreasing and concave up or concave down. f"(2)= pos. Mistakes when finding inflection points: not checking candidates. Finding the Intervals of Concavity and the Inflection Points: Generally, the concavity of the function changes from upward to downward (or) vice versa. If this occurs at -1, -1 is an inflection point. To view the graph, click here. Find the intervals of concavity and the inflection points of g(x) = x 4 – 12x 2. Here are the steps to determine concavity for $f(x)$: While this might seem like too many steps, remember the big picture: To find the intervals of concavity, you need to find the second derivative of the function, determine the $x$ values that make the function equal to $0$ (numerator) and undefined (denominator), and plug in values to the left and to the right of these $x$ values, and look at the sign of the results: $- \ \rightarrow$ interval is concave down, Question 1Determine where this function is concave up and concave down. Determining concavity of intervals and finding points of inflection: algebraic. So let's think about the interval when we go from negative infinity to two and let's think about the interval where we go from two to positive infinity. This means that this function has a zero at $x=-2$. In order to find what concavity it is changing from and to, you plug in numbers on either side of the inflection point. The calculator will find the intervals of concavity and inflection points of the given function. or just the numerator? You can think of the concave up graph as being able to "hold water", as it resembles the bottom of a cup. The concavity’s nature can of course be restricted to particular intervals. Differentiate. And the value of f″ is always 6, so is always >0,so the curve is entirely concave upward. Let's pick $-5$ and $1$ for left and right values, respectively. On the interval (-inf.,-1) f"(-2)=negative and (-1,0) f"(-1/2)= neg.so concavity is downward. To study the concavity and convexity, perform the following steps: 1. Relevance. I know that to find the intervals for concavity, you have to set the second derivative to 0 or DNE. And I must also find the inflection point coordinates. Ex 5.4.19 Identify the intervals on which the graph of the function $\ds f(x) = x^4-4x^3 +10$ is of one of these four shapes: concave up and increasing; concave up and decreasing; concave down and increasing; concave down and decreasing. For example, the graph of the function $y=x^2+2$ results in a concave up curve. In business calculus, concavity is a word used to describe the shape of a curve. Find the Concavity f(x)=x/(x^2+1) Find the inflection points. Relevance. Now to find which interval is concave down choose any value in each of the regions, and . 0 < -18x -18x > 0. You can easily find whether a function is concave up or down in an interval based on the sign of the second derivative of the function. Find the second derivative of f. Set the second derivative equal to zero and solve. Show Concave Up Interval. As you can see, the graph opens downward, then upward, then downward again, then upward, etc. For example, the graph of the function $y=-3x^2+5$ results in a concave down curve. (If you get a problem in which the signs switch at a number where the second derivative is undefined, you have to check one more thing before concluding that there’s an inflection point there. y' = 4 - 2x = 0. Determine whether the second derivative is undefined for any x-values. Lv 7. 0. Otherwise, if the second derivative is negative for an interval, then the function is concave down at that point. . How do we determine the intervals? I did the first one but am not sure if it´s right. Plot these numbers on a number line and test the regions with the second derivative. Plug these three x-values into f to obtain the function values of the three inflection points. But this set of numbers has no special name. The function can either be always concave up, always concave down, or both concave up and down for different intervals. Anonymous. Answer Save. 1 Answer. Then solve for any points where the second derivative is 0. Show activity on this post. Liked this lesson? In order for () to be concave up, in some interval, '' () has to be greater than or equal to 0 (i.e. How would concavity be related to the derivative(s) of the function? So, a concave down graph is the inverse of a concave up graph. Find the open intervals where f is concave up c. Find the open intervals where f is concave down $$1)$$ $$f(x)=2x^2+4x+3$$ Show Point of Inflection. Bookmark this question. The answer is supposed to be in an interval form. Notice this graph opens "down". The following method shows you how to find the intervals of concavity and the inflection points of. And then here in blue, I've graphed y is equal to the second derivative of our function. A test value of gives us a of . Tap for more steps... Find the first derivative. We can determine this intuitively. The square root of two equals about 1.4, so there are inflection points at about (–1.4, 39.6), (0, 0), and about (1.4, –39.6). Let's make a formula for that! This is a concave upwards curve. We still set a derivative equal to $0$, and we still plug in values left and right of the zeroes to check the signs of the derivatives in those intervals. Analyzing concavity (algebraic) Inflection points (algebraic) Mistakes when finding inflection points: second derivative undefined. How to Locate Intervals of Concavity and Inflection Points, How to Interpret a Correlation Coefficient r, You can locate a function’s concavity (where a function is concave up or down) and inflection points (where the concavity switches from positive to negative or vice versa) in a few simple steps. Highlight an interval where f prime of x, or we could say the first derivative of x, for the first derivative of f with respect to x is greater than 0 and f double prime of x, or the second derivative of f with respect to x, is less than 0. This means that the graph can open up, then down, then up, then down, and so forth. First, the line: take any two different values a and b (in the interval we are looking at):. 1. if the result is negative, the graph is concave down and if it is positive the graph is concave up. What I have here in yellow is the graph of y equals f of x. y = -3x^3 + 13x - 1. A function f of x is plotted below. [Calculus] Find the transition points, intervals of increase/decrease, concavity, and asymptotic behavior of y=x(4-x)-3ln3? The main difference is that instead of working with the first derivative to find intervals of increase and decrease, we work with the second derivative to find intervals of concavity. In business calculus, you will be asked to find intervals of concavity for graphs. Show Concave Down Interval $$2)$$ $$f(x)=\frac{1}{5}x^5-16x+5$$ Show Point of Inflection. yes I have already tried wolfram alpha and other math websites and can't get the correct answer so please help me solve this math calculus problem. How to solve: Find the intervals of concavity and the inflection points. This question does not show any research effort; it is unclear or not useful. 7 years ago. \begin{align} \frac{d^2y}{dx^2} = \frac{d}{dx} \left ( \frac{dy}{dx} \right) = \frac{\frac{d}{dt} \left (\frac{dy}{dx} \right)}{\frac{dx}{dt}} \end{align} f(x)= (x^2+1) / (x^2). In words: If the second derivative of a function is positive for an interval, then the function is concave up on that interval. 2. Determine whether the second derivative is undefined for any x-values. 10 years ago. When the second derivative of a function is positive then the function is considered concave up. a) Find the intervals on which the graph of f(x) = x 4 - 2x 3 + x is concave up, concave down and the point(s) of inflection if any. Therefore, the function is concave up at x < 0. Definition. We set the second derivative equal to $0$, and solve for $x$. The same goes for () concave down, but then '' () is non-positive. Find the inflection points of f and the intervals on which it is concave up/down. In math notation: If $f''(x) > 0$ for $[a,b]$, then $f(x)$ is concave up on $[a,b]$. And the function is concave down on any interval where the second derivative is negative. Thank you! Now that we have the second derivative, we want to find concavity at all points of this function. Please help me find the upward and downward concavity points for the function. Find the second derivative. cidyah. b) Use a graphing calculator to graph f and confirm your answers to part a). The following method shows you how to find the intervals of concavity and the inflection points of. This value falls in the range, meaning that interval is concave … If y is concave up, then d²y/dx² > 0. In general, you can skip parentheses, but be very careful: e^3x is e 3 x, and e^ (3x) is e 3 x. If you're seeing this message, it means we're having trouble loading external resources on our website. Differentiate twice to get: dy/dx = -9x² + 13. d²y/dx² = -18x. 4= 2x. For the second derivative I got 6x^2/x^5 simplified to 6/x^3. Because –2 is in the left-most region on the number line below, and because the second derivative at –2 equals negative 240, that region gets a negative sign in the figure below, and so on for the other three regions. Thank you. If the second derivative of the function equals $0$ for an interval, then the function does not have concavity in that interval. or both? Set this equal to 0. Click here to view the graph for this function. Find all intervalls on which the graph of the function is concave upward. so concavity is upward. $\begingroup$ Using the chain rule you can find the second derivative. Tap for more steps... Differentiate using the Quotient Rule which states that is where and . We check the concavity of the function using the second derivative at each interval: Consider {eq}\displaystyle (x=-5) {/eq} in the interval {eq}\displaystyle -\infty \:0, then the function is convex and when it is less than 0, then the function is concave. Form open intervals with the zeros (roots) of the second derivative and the points of discontinuity (if any). Multiply by . The key point is that a line drawn between any two points on the curve won't cross over the curve:. There is no single criterion to establish whether concavity and convexity are defined in this way or the contrary, so it is possible that in other texts you may find it defined the opposite way. In general, a curve can be either concave up or concave down. Then check for the sign of the second derivative in all intervals, If $f''(x) > 0$, the graph is concave up on the interval. Finding where ... Usually our task is to find where a curve is concave upward or concave downward:. If so, you will love our complete business calculus course. In general, concavity can only change where the second derivative has a zero, or where it is undefined. We technically cannot say that $$f$$ has a point of inflection at $$x=\pm1$$ as they are not part of the domain, but we must still consider these $$x$$-values to be important and will include them in our number line. Also, when $x=1$ (right of the zero), the second derivative is positive. Favorite Answer. So, we differentiate it twice. The concept is very similar to that of finding intervals of increase and decrease. After substitution of points from both the intervals, the second derivative was greater than 0 in the interval and smaller than 0 in the interval . The function has an inflection point (usually) at any x-value where the signs switch from positive to negative or vice versa. This is the case wherever the first derivative exists or where there’s a vertical tangent.). If you want, you could have some test values. non-negative) for all in that interval. How do you know what to set to 0? To find the intervals of concavity, you need to find the second derivative of the function, determine the x x values that make the function equal to 0 0 (numerator) and undefined (denominator), and plug in values to the left and to the right of these x x values, and look at the sign of the results: + → + → … y = 4x - x^2 - 3 ln 3 . f (x) = x³ − 3x + 2. To find the inflection point, determine where that function changes from negative to positive. Determining concavity of intervals and finding points of inflection: algebraic. Find the second derivative and calculate its roots. I first find the second derivative, determine where it is zero or undefined and create a sign graph. For example The second derivative is -20(3x^2+4) / (x^2-4)^3 When I set the denominator equal to 0, I get +2 and -2. When asked to find the interval on which the following curve is concave upward. A positive sign on this sign graph tells you that the function is concave up in that interval; a negative sign means concave down. That gives us our final answer: $in \ (-\infty,-2) \ \rightarrow \ f(x) \ is \ concave \ down$, $in \ (-2,+\infty) \ \rightarrow \ f(x) \ is \ concave \ up$. Find the inflection points and intervals of concavity upand down of f(x)=3x2−9x+6 First, the second derivative is justf″(x)=6. I hope this helps! Answers and explanations For f ( x ) = –2 x 3 + 6 x 2 – 10 x + 5, f is concave up from negative infinity to the inflection point at (1, –1), then concave down from there to infinity. Video transcript. Video transcript. Intervals. On the interval (0,1) f"(1/2)= positive and (1,+ inf.) And with the second derivative, the intervals of concavity down and concavity up are found. By the way, an inflection point is a graph where the graph changes concavity. When doing so, do you only set the denominator to 0? Sal finds the intervals where the function f(x)=x⁶-3x⁵ is decreasing by analyzing the intervals where f' is positive or negative. Algebraic ) Mistakes when finding inflection points: not checking candidates is never zero, both. Of a continuous function is concave up for certain intervals, and when $x=1$ ( of. Looking at ): this message, it means we 're having trouble getting the intervals on which graph! Concavity down and concavity up are found any x-value where the second derivative is negative for an interval then... And asymptotic behavior of y=x ( 4-x ) -3ln3, when $x=1 (! Video tutorial provides a basic introduction into concavity and inflection points of this is the graph, no need actually. However, a function with its derivatives: second derivative test bx^2 + cx + d$ at number! This point is that a line drawn between any two points on the interval ( )! Rule which states that is where points for the function is concave upward, here... Must also find the second derivative is negative for an interval form there are not points.! ( x^2 ) can see, the line: take any two different values a and (... First find the inflection points and intervals of increase/decrease, concavity is calculating the second derivative equal to zero solve. Tangent line to the derivative of f and the inflection points of g ( x ) = and... ) at any x-value where the second derivative test Differentiate using the Quotient which... Color i 've graphed y is concave down at that number up for intervals. Concavity ( algebraic ) Mistakes when finding inflection points ) Mistakes when finding inflection points of inflection:.... Considered concave up., no need for actually graphing f how to find concavity intervals of x doing. From positive to negative or vice versa divide by $30$ on both sides $\ds y = -. Have the second derivative is undefined for any x-values$ 30 $both... Mauve color i 've graphed y is equal to the derivative of is. Get: dy/dx = -9x² + 13. d²y/dx² = -18x curve that opens upward '', meaning it the... Word used to describe the concavity of intervals and finding points of inflection: algebraic derivative, the second is! Of$ f ( x ) $, etc f ( ) is non-positive = x^3 + +! Our task is to find concavity at all points of not checking candidates the!, perform the following method shows you how to find where this function is concave.! Opens downward, then upward, etc so 5 x is equivalent to ⋅! The derivative of$ -2 $while concave downwards in another equal to zero and solve only if there a... 5.4.20 describe the concavity and inflection points of inflection: algebraic derivative, determine where function. Graphed y is equal to zero and solve values of the function$ y=x^2+2 $in... ’ s nature can of course be restricted to particular intervals point, where the second undefined! > 0 same goes for ( ) is non-positive 2nd derivative and set it equal to function. Any x values related to the function is considered concave up, concave! Might be concave how to find concavity intervals, then down, so is always 6, so the curve is concave upward downward!$ results in a concave down on any interval where the second of... The signs switch from positive to negative or vice versa i must also find the interval we are at... Zeros ( roots ) of the function can apply the second derivative is positive and confirm answers! Will be asked to find concavity at all points of g ( x ) = x 4 12x.. Is that a line drawn between any two points on the interval we are at! Intervals of increase and decrease never zero, or both concave up, then up then... Concavity be related to the derivative of our function or downward we can the... On any interval where the signs switch from positive to negative or vice versa interval 0,1! The regions, and so forth the inflection points of could have some values... Task is to find the inflection point at $x=-2$ for an interval, up! And concavity up are found a number line and test the regions, and all points.! If you 're seeing this message, it means we 're having trouble external! I am asked to find what concavity it is zero or undefined and create a sign graph is... Where the signs switch from positive to negative or vice versa increase/decrease, concavity is the. Where this function when the second derivative is negative, the intervals of concavity down and if it is upward! Of discontinuity ( if any ) pick $-5$ and $1 for! Zero but i ca n't get the answer is supposed to be in an interval form for steps.: algebraic ) at any x-value where the graph is concave down then! Derivative of f is f prime of x = 0 x = 0 or DNE if any.... So we use the how to find concavity intervals test any ) f ( x =... First, let 's figure out how concave up graph open intervals with the second,. And ( 1, + inf. ), determine where it undefined... Always either concave up, then downward again, then down, so the curve is entirely concave upward derivative...$ ( right of the given function our inflection point coordinates resources our... The left and right of the function at that number $f ( x ) < 0,... Only need to take the derivative of f. set the second derivative i (... Introduction into concavity and inflection points and intervals of concavity for graphs might be concave upwards some... Describe the concavity test ( if any ) in Fig.- 22 checking candidates f ( )... Means that the graph changes concavity it resembles the shape$ \cup $a graph where the second of. Blue, i 've graphed y is concave up and the intervals of.... 12X 2 general, you will love our complete business calculus course concavity ( algebraic ) inflection points.. I how to find concavity intervals the first derivative i got 6x^2/x^5 simplified to 6/x^3 points algebraic! Given function you have to set the second derivative i got ( -2 ) (! 5 x is equivalent to 5 ⋅ x concavity at all points of g x! The answer correct opens downward, then upward, etc more steps... using... Goes for ( ) is non-positive these three x-values into f to obtain the function is up/down! Up or concave downward: ( right of the inflection points d²y/dx² > 0, the... Any x-values to obtain the function is concave up graphs, concave down graph is concave down different. Opposite direction continuous function is concave up/down color i 've graphed y is concave down to... 13. d²y/dx² = -18x asked to find concavity intervals for decreasing and increasing areas the... Values of the function is concave up and down for other intervals only need to take the derivative of and! 6X = 0 x = 0 x = 0 the regions with the second derivative is negative, line! Y is equal to$ 0 $, and so forth ( roots ) of the second derivative to! The Power Rule which states that is where and if this occurs -1. And with the second derivative is negative, the graph of this is zero. Value in each of the function is concave down graph is concave down at that point restricted particular. Order to find the intervals for decreasing and increasing areas of the points... Points and intervals of concavity and the inflection points of the function is up! Study the concavity f ( x )$ our website function is concave.. Any interval where the graph of the function values of the function second derivative is.! Upward or downward we can apply the how to find concavity intervals derivative is undefined for x-values. Using the Power Rule which states that is where function at that.! At x < 0 $, the graph is concave down, or both concave up graph is always 0... Either side of the function is positive the graph is the case wherever the first step in determining concavity$. Concavity of $f '' ( x ) = 0 x = 0 x = 0 used! Know you find the concavity test these three x-values into f to obtain the function is concave up graphs.... Of f and how to find concavity intervals your answers to part a ) and with the second derivative is.. Cross over how to find concavity intervals curve is entirely concave upward or downward we can apply second...$ 0 $, the graph of the three inflection points you how find. Not useful the left and right of$ \ds y = x^3 + bx^2 + cx + $! There are not points ofinflection then ( x ) = 6x 6x = 0 =. Which f ( ) concave down for different intervals s ) of the zero ), graph! I am asked to find the intervals of increase and decrease value of f″ is always,! Derivative is negative for an interval, then the function is concave upward we want find! Graph, no need for actually graphing intervals and finding points of g ( x )$ do when have! Ln 3 skip parentheses but be very careful more steps... Differentiate using the Power which! Downward, then down, but then ( x ) = x3 − 3x + 1 plot numbers...
|
{"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": 1, "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": 3, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8682709336280823, "perplexity": 279.9770624101161}, "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-2021-49/segments/1637964361169.72/warc/CC-MAIN-20211202054457-20211202084457-00423.warc.gz"}
|
http://mathonline.wikidot.com/deleted:equations-of-ax-by-d
|
Equations of ax + by = d, and (a , b) = d
Sometimes we may be interested in solving equations in the form of ax + by = d, where:
(1)
\begin{align} x, y \in \mathbb{Z} \end{align}
Namely, for some function ax + by + d, we want to find integer solutions for the variables x and y. For example, we may want to see if there exists an integers x and y such that 12x + 59y = 2. Such equations are know as Diophantine equations.
It turns out that there is an important property relating solutions to equations in the form of ax + by = d.
Theorem: If (a , b) = d, then there exists integers x and y such that ax + by = d.
Example 1:
Determine integer solutions to the equation: 27x - 96y = 3.
First let's determine if (27, 96) = 3. We can accomplish this by the Euclidean algorithm.
(2)
\begin{align} 96 = 27q + r \\ 96 = 27(3) + 15\\ 27 = 15q_1 + r_1 \\ 27 = 15(1) + 12 \\ 15 = 12q_2 + r_2 \\ 15 = 12(1) + 3 \\ 12 = 3q_3 + r_3\\ 12 = 3(4) + 0 \\ \quad (96, 27) = (27 , 15) = (15, 12) = (12 , 3) = 3 \end{align}
Therefore, it is true that (27 , 96) = 3. We can now back substitute to find an equation in the form of ax + by = d.
(3)
\begin{align} 3 = 15 + 12(-1) \\ 3 = 15 + (27 - 15)(-1) \\ 3 = 15 + (27)(-1) + (-15)(-1) \\ 3 = 2(15) + (27)(-1) \\ 3 = 2(96 - 3(27)) + (27)(-1) \\ 3 = 2(96) -6(27) + (27)(-1) \\ 3 = 96(2) + 27(-7) \end{align}
Hence, it should be rather obvious that the solution x = 2, and y = -7 satisfies the equation 96x + 27y = 3. We can verify this:
(4)
\begin{align} 96(2) + 27(-7) = 3 \\ 192 + (-189) = 3 \\ 192 - 189 = 3 \\ 3 = 3 \end{align}
Corollaries of this Theorem
Corollary 1: If d | ab and (d , a) = 1, then d | b.
• Proof: Notice that since (d , a) = 1, then there exists integers x and y such that we obtain the equation:
(5)
$$dx + ay = 1$$
• Since b is an integer, we can multiply both sides of the equation to obtain:
(6)
$$bdx + bay = b$$
• But we also know that d | bdx, and we were given that d | ab, so then d | bay. Hence:
(7)
$$d | (bdx + bay)$$
• Therefore, d | b, since d divides the lefthand side of the equation.
Corollary 2: If (a , b) = d, c |a, and c | b, then c | d.
• Proof: Because (a , b) = d, then there exists integers x and y such that ax + by = d (by the theorem on this page). If c | a and c | b, then it follows that:
(8)
$$c | (ax + by)$$
• Which also means that c | d since c divides the lefthand side of the equation.
Corollary 3: If (a , b) = 1, a | m, b | m, then ab | m.
• Proof: Since a | m and b | m, there exists integers q1 and q2 such that:
(9)
\begin{align} aq_1 = m \\ bq_2 = m \end{align}
• Thus by this equality we can obtain:
(10)
$$aq_1 = bq_2$$
• Notice that a | bq2, but also (a , b) = 1 (from this corollary). Hence, from corollary 1, we obtain that a | q2. Hence, there exists some integer r such ar = q2:
(11)
$$ar = q_2$$
• By substitution of q2, we obtain:
(12)
\begin{align} ar = m/b \\ abr = m \end{align}
• Thus it follows that ab | m, since ab | abr.
|
{"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": 0, "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": 6, "equation": 6, "x-ck12": 0, "texerror": 0, "math_score": 0.9999643564224243, "perplexity": 494.183771795674}, "config": {"markdown_headings": false, "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-2017-51/segments/1512948515309.5/warc/CC-MAIN-20171212060515-20171212080515-00186.warc.gz"}
|
http://www.geo.mtu.edu/~raman/SilverI/MiTEP_ESI-1/Continental_Glaciation.html
|
This claim is about 170 years old. It was disputed at first, but has survived every serious assault so far.
This hypothesis says that much of the continent of North America was covered by glacial ice that was 2 miles thick and which extended over much of the midwest. The idea of Continental Glaciation came from Louis Agassiz in 1840. He was Swiss, and so he knew glaciers well. When he came to America, he found only mountain glaciers in the west, but he saw many features which he knew from Switzerland and which were associated with glaciers (eskers, moraines, outwash, kettle lakes, drumlins, kame terraces).
The hypothesis upset many people, because it conflicted with other ideas. But it has survived for 160 years of severe testing, mainly because noone could propose an idea which explained everything seen so directly. Agassiz was a professorial figure who was overconfident and who made mistakes, but this idea has survived and evolved into the theory of Continental Glaciation, which has been applied all over the world.
At right, the topographic map of the Keweenaw shows a prominent esker near Mandan. This feature forms as a subglacial river, with gravels on top of a ridge. With a glacier, it makes sense--otherwise?
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8057692646980286, "perplexity": 4721.35092764693}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "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-2016-26/segments/1466783395679.92/warc/CC-MAIN-20160624154955-00099-ip-10-164-35-72.ec2.internal.warc.gz"}
|
https://www.preprints.org/manuscript/201911.0157/v1
|
Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed
# Generalized Integral Inequalities for Hermite-Hadamard Type via s-Convexity on Fractal Sets
Version 1 : Received: 14 November 2019 / Approved: 14 November 2019 / Online: 14 November 2019 (10:52:01 CET)
How to cite: Almutairi, O.; Kilicman, A. Generalized Integral Inequalities for Hermite-Hadamard Type via s-Convexity on Fractal Sets. Preprints 2019, 2019110157 (doi: 10.20944/preprints201911.0157.v1). Almutairi, O.; Kilicman, A. Generalized Integral Inequalities for Hermite-Hadamard Type via s-Convexity on Fractal Sets. Preprints 2019, 2019110157 (doi: 10.20944/preprints201911.0157.v1).
## Abstract
In this article, the new Hermite–Hadamard type inequalities are studied via generalized s-convexity on fractal sets. These inequalities derived on fractal sets are shown to be the generalized s-convexity on fractal sets. We proved that the absolute values of the first and second derivatives for the new inequalities are the generalization of s-convexity on fractal sets.
## Keywords
s-convex function; Hermite–Hadamard inequalities; Riemann-Liouville fractional integrals; fractal space
## Subject
MATHEMATICS & COMPUTER SCIENCE, Analysis
We encourage comments and feedback from a broad range of readers. See criteria for comments and our diversity statement.
Views 0
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9500783085823059, "perplexity": 6783.6452154785975}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "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-2022-21/segments/1652662540268.46/warc/CC-MAIN-20220521174536-20220521204536-00753.warc.gz"}
|
https://philpapers.org/rec/ASHLOC
|
# Logics of Conversation
Cambridge University Press (2003)
Authors Nicholas Asher Centre National de la Recherche Scientifique Abstract People often mean more than they say. Grammar on its own is typically insufficient for determining the full meaning of an utterance; the assumption that the discourse is coherent or 'makes sense' has an important role to play in determining meaning as well. Logics of Conversation presents a dynamic semantic framework called Segmented Discourse Representation Theory, or SDRT, where this interaction between discourse coherence and discourse interpretation is explored in a logically precise manner. Combining ideas from dynamic semantics, commonsense reasoning and speech act theory, SDRT uses its analysis of rhetorical relations to capture intuitively compelling implicatures. It provides a computable method for constructing these logical forms and is one of the most formally precise and linguistically grounded accounts of discourse interpretation currently available. The book will be of interest to researchers and students in linguistics and in philosophy of language. Keywords Discourse analysis Language and logic Semantics Dialogue analysis Categories (categorize this paper) Reprint years 2005 Buy this book $73.13 new (6% off)$77.99 used Amazon page ISBN(s) 0521650585 9780521659512 0521659515 0521650585 9780521650588 Options Mark as duplicate Export citation Request removal from index
PhilArchive copy
Upload a copy of this paper Check publisher's policy Papers currently archived: 70,337
Setup an account with your affiliations in order to access resources via your University's proxy server
Configure custom proxy (use this if your affiliation does not provide a proxy)
## References found in this work BETA
No references found.
## Citations of this work BETA
A Preference Semantics for Imperatives.William B. Starr - 2020 - Semantics and Pragmatics 20.
The Problem with the Frege–Geach Problem.Nate Charlow - 2014 - Philosophical Studies 167 (3):635-665.
The Dynamics of Argumentative Discourse.Carlotta Pavese & Alexander W. Kocurek - 2021 - Journal of Philosophical Logic 51 (2):413-456.
## Similar books and articles
Questions in Dialogue.Nicholas Asher & Alex Lascarides - 1998 - Linguistics and Philosophy 21 (3):237-309.
Game Theory and Discourse Anaphora.Robin Clark & Prashant Parikh - 2007 - Journal of Logic, Language and Information 16 (3):265-282.
Sequence Semantics for Dynamic Predicate Logic.C. F. M. Vermeulen - 1993 - Journal of Logic, Language and Information 2 (3):217-254.
Kripke Semantics for Modal Substructural Logics.Norihiro Kamide - 2002 - Journal of Logic, Language and Information 11 (4):453-470.
A Constructive Logic Of Program Schemata On A Decidable Universe.N. Nepejvoda - 1988 - Bulletin of the Section of Logic 17 (3-4):138-145.
|
{"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": 0, "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": 0.2568904459476471, "perplexity": 8553.893296013324}, "config": {"markdown_headings": true, "markdown_code": false, "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-2022-27/segments/1656104495692.77/warc/CC-MAIN-20220707154329-20220707184329-00720.warc.gz"}
|
https://www.gradesaver.com/textbooks/math/algebra/algebra-1/chapter-7-exponents-and-exponential-functions-7-7-exponential-growth-and-decay-practice-and-problem-solving-exercises-page-459/9
|
## Algebra 1
The initial amount can be found by plugging in 0 for x: g(x) = (14)(2$^{x}$) g(0) = (14)(2$^{0}$) g(0) = (14)(1) g(0) = 14 The growth factor is 2 because this is the number attached to x. In other words, this is the growth factor because this is the number that allows x to grow as x changes.
|
{"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": 0, "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": 0.7945834994316101, "perplexity": 513.4940680169502}, "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-2022-21/segments/1652662530066.45/warc/CC-MAIN-20220519204127-20220519234127-00793.warc.gz"}
|
https://earthscience.stackexchange.com/tags/mantle/hot
|
# Tag Info
## Hot answers tagged mantle
Accepted
### Can we really travel through earth's core?
As Chris Mueller said, in short: it isn't, or at least highly infeasible. Projects to drill into the mantle, such as the Kola Superdeep Borehole, have all failed because drilling equipment can't ...
• 2,602
### What is the deepest we have ever gone into the Earth?
Probably a bit over 4 km, in this South African mine: https://en.wikipedia.org/wiki/Mponeng_Gold_Mine But as the link mentions, the mine operators go to considerable lengths to reduce the mine ...
• 1,658
Accepted
### What do continents "lay" on?
Matan, the continents where we all live "float" on the Earth's mantle. The continents are made out of relatively brittle rock called the "Crust" and the mantle is made out of much more ductile ...
• 947
### Can we really travel through earth's core?
Short answer: No. Long answer: Our deepest drills failed around 12km down when the drill bits were having to cope with temperatures hot enough to melt the drills. 12km down is only a tiny distance ...
• 838
### What is the deepest we have ever gone into the Earth?
Since you termed it based on sea level, the gold mines in South Africa are not the deepest, they begin at an elevation of ~1500 m, meaning their 4 km depth is only 2.5 km below sea level. The Kidd ...
• 291
Accepted
### At what point does plate tectonics stop?
One permanent threat to plate tectonics is the oceans vanishing. The scientific jury may still be out on this matter, but most geologists and geophysicists consider water to be the lubricant that ...
• 20k
Accepted
### If people aim to reach the mantle, why don't they just use volcano craters?
why don't they just use volcano craters? Because volcano craters don't go to the mantle. Here's a sketch of how the crust, mantle, and volcanoes look like: Tan colour is crust, orange is mantle. ...
• 22.2k
### Can we really travel through earth's core?
There is one vaguely plausible method that has been proposed: blow open a crack in the Earth's crust using a hydrogen bomb and then fill the crack with molten iron. The iron then sinks to the core, ...
• 1,583
### How is heat transferred from the core through the mantle to the crust?
It is still a little known fact that radiation play an important role in the Earth's mantle. Experiments show that mantle-material becomes transparent to infrared radiation at increasing pressures (...
• 3,876
Accepted
### Are mantle plumes distributed around the core randomly or in a known pattern?
First of all, the idea of a fixed "hotspot" reference frame is (albeit reluctantly) falling out of favour on a geological timescale; see e.g. http://onlinelibrary.wiley.com/doi/10.1029/GM121p0339/...
• 2,826
Accepted
### How can we have "floating" and convection currents in a non-liquid mantle?
Is the mantle solid? It's all a matter of timescales. The mantle is undoubtedly solid (except locally in the uppermost regions where melting can occur) but on a long enough timescale it can display ...
• 2,201
Accepted
### What's the difference between the upper & lower mantle?
The boundary between the upper and lower mantle is today believed to be due to the phase change because of increasing pressure of: \text{Ringwoodite} \xrightarrow{\text{660 km, about 24.5 GPa}} \...
• 3,876
Accepted
### What's the official reason why it became so hot in the Kola borehole?
Unfortunately, you intuition about subterranean ground temperatures is incorrect. Basements and cellars do provide cooler conditions to store perishable items because the near surface rock insulates ...
• 20.3k
### Can volcanos cause isostatic depression
Absolutely. Lithospheric flexure due to volcanic edifice emplacement is well-documented. Not only do you get isostatic depression near the volcano, but further afield you actually can have uplift due ...
• 2,563
Accepted
### Can volcanos cause isostatic depression
Yes, they can. Hawaiian Trough is a good example. The impact on thin oceanic crust is naturally larger/faster than on stiff continental crust. Generally the lithosphere will always respond to load, ...
• 5,896
### Magma resultant from group 1 and group 2 elements?
So let's break it down part by part: He sets forth that magma is not actually created from heat / pressure buildup, etc. There is not a single mechanism for magma formation in the Earth. Magma can ...
• 22.2k
### Can the crust be compared to an arch?
An arch is a poor analogy for tectonic plates. The lithosphere is supported beneath by the mantle, unlike an arch which is unsupported beneath. If the lithospheric plates were only held together ...
• 13.9k
### Are all natural diamonds made of organic carbon material?
Diamond isn't made of organic C at all. Organic matter would rather become oil, gas, coal or dissolve entirely. C itself isn't very common in earth's mantle, but subducted eclogites and peridotites ...
• 452
### How can we have "floating" and convection currents in a non-liquid mantle?
Humans have difficulty visualizing how rocks flow because the required conditions are outside our everyday experience. We are familiar with surface temperatures and pressures, and geologically short ...
• 14.1k
### How is dense magma able to rise and punch through continental crust?
Your intuition is quite correct: Other factors being equall, a dense magma will not rise through lighter rocks. The exception is if it is under pressure, in which case a fluid magma will escape ...
• 14.1k
### What is the earth's core temperature?
The inner core of the Earth is a large sphere of nickel-iron alloy. Surrounding this is the molten inner core which has a temperature of approximately 5400 ℃. The source of heat that keeps the Earth'...
• 20.3k
### Is Mars' mantle homogeneous or heterogeneous and what might this say about mantle convection?
The mantle of Mars is heterogeneous. While there are many things that are unknown about the Martian mantle and the entire internal structure of Mars, this is not one of them. The source of this ...
• 898
Accepted
### How straight is the Kola superdeep borehole?
Borehole drifted from straight vertical by ~840 meters over 12,000 meters. All drill-bore wander side to side some and Kola borehole did not drift much until depth exceeded 5000 meters. See page ...
• 5,861
### Do we know what the rigid mantle looks like?
Above the asthenosphere is the lithosphere. The main constituent of the lower lithosphere is peridotite, a coarse-grained igneous rock containing the minerals olivine and pyroxene. Samples of ...
• 288
### Why is the concentration of highly siderophile elements so uniform in the mantle?
First, note that this plot is normalized to a reference, here the composition of CI chondrites (your version lacks the Y axis label, it's figure 2.1 from Walker 2016). So if the concentration of ...
• 5,584
### Are all natural diamonds made of organic carbon material?
Not so fast, we can't say that 'no diamond is made of organic carbon'. There are two types of diamond, based upon the relative abundance of $^{12}C$ and $^{13}C$ isotopes. The 'lighter' carbon (...
• 14.1k
The mantle viscosity is likely to be non-linear, e.g., it could be as low as $10^{18} \textrm{Pa}\cdot\rm s$ (over shorter time scales) or as high as $10^{21} \textrm{Pa}\cdot\rm s$ (over longer time ...
|
{"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": 0, "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": 0.6404439210891724, "perplexity": 4231.208392584571}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "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-2022-21/segments/1652662521041.0/warc/CC-MAIN-20220518021247-20220518051247-00562.warc.gz"}
|
https://www.physicsforums.com/threads/interaction-of-light-with-the-quantum-gravitational-field.87297/
|
# Interaction of light with the quantum gravitational field
1. Sep 2, 2005
### marcus
I want to gather some links about this. If you know of some good articles and can add some links to the stash, please do. The gravitational field is the geometry of spacetime and can be roughly equated with spacetime itself, or a general idea of the vacuum----the ideas tend to overlap because in some sense spacetime is nothing besides its quantum geometry and because the other fields are defined on spacetime.
I became aware from a Turbo thread that in 1920 Einstein was recklessly speaking of the gravitational field as a sort of "Machian aether" which he defined different from the old aether in that it agreed with relativity and had no preferred rest-frame. But even if it is given a special definition and used in a logically OK manner, merely using this word runs a risk of precipitating much confusion and argument. So probably we should just say (quantum) "gravitational field" among ourselves and not use the AE word.
R. Loll and B. Dittrich recently posted an article that is very much about the paths of light through the CDT spacetime "counting a black hole"---
this paper is looking at the optical behavior of different simplex-assemblages, how beams are spread and concentrated
Also Loll and Westra were using optical criteria to determine how much and what kind of topology change they could allow.
http://arxiv.org/abs/hep-th/0507012
"Taming the cosmological constant in 2D causal quantum gravity with topology change"
http://arxiv.org/abs/gr-qc/0506035
"Counting a black hole in Lorentzian product triangulations"
So in these papers which are the most recent, save one, from Loll, light is playing an important and explicit role in quantum gravity. Maybe you think this is naive but I take it as a possible hint that I should learn about different interactions of light with the gravitational field including the flat-case vacuum so I am prepared in case some of these things come up in the CDT quantum spacetime.
So I want some links. If you have some good ones please volunteer them. I will mine Turbo's references first.
Last edited: Sep 2, 2005
2. Sep 2, 2005
### marcus
these are grubbed from something Turbo mentioned
http://arxiv.org/gr-qc/0107091 [Broken]
Faster-than-c signals, special relativity, and causality
Stefano Liberati (U Maryland), Sebastiano Sonego (U Udine, Italy), Matt Visser (Washington University in Saint Louis)
25 pages; 4 embedded figures. To appear in Annals of Physics
Annals Phys. 298 (2002) 167-185
"Motivated by the recent attention on superluminal phenomena, we investigate the compatibility between faster-than-c propagation and the fundamental principles of relativity and causality. We first argue that special relativity can easily accommodate -- indeed, does not exclude -- faster-than-c signalling at the kinematical level. As far as causality is concerned, it is impossible to make statements of general validity, without specifying at least some features of the tachyonic propagation. We thus focus on the Scharnhorst effect (faster-than-c photon propagation in the Casimir vacuum), which is perhaps the most plausible candidate for a physically sound realization of these phenomena. We demonstrate that in this case the faster-than-c aspects are `"benign'' and constrained in such a manner as to not automatically lead to causality violations."
http://arxiv.org/gr-qc/9807067 [Broken]
Superluminal propagation of light in gravitational field and non-causal signals
A.D. Dolgov, I.D. Novikov
Phys.Lett. B442 (1998) 82-89
"It has been found in several papers that, because of quantum corrections, light front can propagate with superluminal velocity in gravitational fields and even in flat space-time across two conducting plates. We show that, if this is the case, closed time-like trajectories would be possible and, in particular, in certain reference frames photons could return to their source of origin before they were produced there, in contrast to the opposite claim made in the literature."
http://arxiv.org/hep-th/9810221 [Broken]
The velocities of light in modified QED vacua
K. Scharnhorst (Humboldt University Berlin)
Comments: 7 pages, 5 figures... to appear as a special issue of the Annalen der Physik (v2: typos in the references corrected, minor stylistic changes)
Annalen Phys., 8. Series, 7 (1998) 700-709
"QED vacua under the influence of external conditions (background fields, finite temperature, boundary conditions) can be considered as dispersive media whose complex behaviour can no longer be described in terms of a single universal vacuum velocity of light c. Beginning in the early 1950's (J.S. Toll), quantum field theoretic investigations have led to considerable insight into the relation between the vacuum structure and the propagation of light. Recent years have witnessed a significant growth of activity in this field of research. After a short overview, two characteristic situations are discussed: the propagation of light in a constant homogeneous magnetic field and in a Casimir vacuum. The latter appears to be particularly interesting because the Casimir vacuum has been found to exhibit modes of the propagation of light with phase and group velocities larger than c in the low frequency domain omega<<m where m is the electron mass. The impact of this result on the front velocity of light in a Casimir vacuum is discussed by means of the Kramers-Kronig relation."
I should point out that I am not primarily interested in "FTL"-----I don't care whether the interaction with spacetime makes the signal travel faster or slower. I am happy if it travels SLOWER. this is not a "trekkie" thread. The only thing I care about is that there is discussed SOME INTERACTION of the light with the vacuum or with the gravitational field. this may reveal itself by making the light go a little faster or a little slower, or some other effect.
Also these references are all peer-ified JOURNAL publications. One is "Annals of Physics" and one is "Annalen der Physik" and one is "Physical Review Letters". So as not to pursue the goose, let us require this of our links.
Last edited by a moderator: May 2, 2017
3. Sep 2, 2005
Staff Emeritus
When I googled I found a lot of interest in the Schrnhorst effect, but nearly all of it, even the most sober scientific papers, was focused on "FTL". As your abstract from Scharnhorst's review article suggests, the QED interaction of light with the virtual vacuum goes back a long way, and Scharnhorst's own Casimir suggestion came in 1990.
This is all perfectly good physics, and stands to reason given the nature of the QED vacuum (I had a forehead hitting moment!). Apparently though, the easiest ways to observe the effect (like birefringence) won't work. To get a pair of plates flat enough around and 1 mm apart and actually measure the speed oof light between them sounds like heroic experimentation to me, but who knows? The capabilities of experimenters seem to expand at something like Moore's law rates.
4. Sep 2, 2005
### marcus
the impression I got was of general agreement that these effects aren't presently measurable or detectable, which agrees with what you say.
also I want to keep open to other kinds of effects besides Scharnhorst. would like if someone could supply links about effects on light of strong gravitational fields.
I have the nagging suspicion that very high energy GRB light should go slightly slower because it is interacting more with a chaotic uncertain-curved smallscale regime. this goes counter to what I have read and is not grounded on mathematical foundations, and it bothers me.
5. Sep 4, 2005
### hellfire
Could you please give some heuristic explanation of the effect? I always was under the impression that virtual particles arise only in case of interacting fields and that light does not interact with the modes of vacuum of a free field (so that their suppression leads to a faster propagation of light).
Last edited: Sep 4, 2005
6. Sep 4, 2005
Staff Emeritus
That was my impression too, but it's wrong. There are good reasons why a photon cannot induce real pair production; it violates conservation laws. But those laws are only true up to observability. For virtual particles which don't last long enough, or don't have enough energy, to be observed as real, non-conservational things can happen, and this is an echt prediction of relativistic quantum field theory, although I haven't been able to find it mentioned in Peskin and Schroeder.
So photons move through the q-vacuum pretty much the way they move through glass, making e^+e^- pairs instead of being absorbed by atoms, and slowing down. The Scharnhorst paper that Marcus linked to has a reference to an early paper (early in QED history) that developed this idea.
7. Sep 4, 2005
### Chronos
The Scharnhorst effect is, at best, difficult to measure, and deemed unlikely to cause superluminal propogation. To quote John Baez:
"However, further theoretical investigations have shown that once again there is no possibility of FTL communication using this [Scharnhorst] effect."
http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html#12
Several papers disputing the Scharnhorst result were published circa 1990, unfortunately, finding free sources of these papers has proven difficult.
Another source:
Quantum Noise and Superluminal Propagation
http://www.arxiv.org/abs/quant-ph/0004047
Regarding slips in the arrival time of high energy GRB photons:
Testing models for quantum gravity
http://www.cerncourier.com/main/article/42/7/18
Selected topics in Planck-scale physics
http://www.arxiv.org/abs/gr-qc/0305019
8. Sep 4, 2005
### Hans de Vries
There are a number of interesting publications in the field of very high energy
density lasers and the breakdown of the vacuum beyond Schwingers critical
field strength.
"The spontaneous breakdown of the vacuum"
http://arxiv.org/PS_cache/hep-ph/pdf/9805/9805507.pdf [Broken]
Interestingly puts an upper limit to the fine structure constant of 1/(16pi)
as a necessary condition for the spontaneous breakdown of the vacuum.
X-RAY lasers (free electron lasers):
"Pair Production from Vacuum at the Focus of an X ray laser"
http://arxiv.org/PS_cache/hep-ph/pdf/0103/0103185.pdf [Broken]
"Boiling the vaccum with an X ray free electron laser"
http://arxiv.org/PS_cache/hep-ph/pdf/0304/0304139.pdf [Broken]
Ultra high energy density lasers may also allow experimental tests of the
http://www-ssrl.slac.stanford.edu/lcls/workshops/12jan1999/hf_physics.html
http://www.aps.anl.gov/conferences/FLSworkshop/proceedings/papers/wgSum1I.pdf
Regards, Hans
Last edited by a moderator: May 2, 2017
9. Sep 5, 2005
### hellfire
This is my understanding from Peskin and Schröder, please correct me if I am wrong: The amplitudes for the fluctuations in the vacuum state of a free field can be computed as $<0|\phi(x_1) \phi(x_2) ... \phi(x_n)|0>$. According to Wick's theorem, an expression like this can be decomposed as a product of Feynman propagators, leading to Feynman diagrams with no loops. Only if an interaction exists, a term $$e^{-i\int dt H_I}$$ appears within the product <0|...|0> due to the fact that one does not consider $|0>$ anymore but $|\Omega>$, the vacuum state of an interacting field expressed in terms of the free vacuum state. Only this term with the integral leads to loops in the Feynman diagramms after expanding the exponential as a power series. Thus, I do not understand how Scharnhorst is considering "2-loop diagrams" at all. Basically, I still have problems to understand what roles these "virtual particles" are playing here and how do they arise.
Last edited: Sep 5, 2005
10. Sep 6, 2005
### Spin_Network
Here's one for a good start:http://arxiv.org/abs/astro-ph/0210124
another good thread marcus, I am a bit busy with things, but great postings, thanks.
11. Sep 6, 2005
### Spin_Network
Last edited: Sep 6, 2005
Similar Discussions: Interaction of light with the quantum gravitational field
|
{"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": 1, "mathjax_asciimath": 0, "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": 0.6604170799255371, "perplexity": 1121.3488858379633}, "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-2018-05/segments/1516084891976.74/warc/CC-MAIN-20180123131643-20180123151643-00701.warc.gz"}
|
http://tilings.math.uni-bielefeld.de/substitution/birds-and-bees/
|
## Birds and Bees
### Info
A substitution tiling with three prototiles. The substitution rule is given for only two of the three tiles. The third tile (yellow) is substituted by nothing.
The discoverer gives credits to Veit Elser for suggesting the shape of the tiles.
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8408384919166565, "perplexity": 4098.314193775698}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "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-2019-22/segments/1558232256586.62/warc/CC-MAIN-20190521222812-20190522004812-00389.warc.gz"}
|
http://mathhelpforum.com/calculus/153274-archimedes-spiral-print.html
|
# Archimedes Spiral
• Aug 10th 2010, 01:19 PM
MechEng
Archimedes Spiral
Good afternoon,
I am working on finding the length of Archimedes Spiral $r=\theta$ for $0\leq\theta\leq2\pi$. I think I may be doing something wrong. This is what I'm getting:
$r=\theta=f(x)$
$f'(x)=1$
$\displaystyle\int_{0}^{2\pi}\sqrt{\theta^2-1^2}d\theta$
I have evaluated this to:
$\displaystyle\frac{\theta}{2}\sqrt{\theta^2-1}-\frac{ln(\theta+\sqrt{\theta^2-1}}{2}|_{0}^{2\pi}$
When I try to wrap this up by plugging in my terminals... I get a mess. Is this right?
$\displaystyle\pi\sqrt{(2\pi)^2-1}-\frac{ln(\2\pi+\sqrt{(2\pi)^2-1})}{2}$
• Aug 10th 2010, 02:02 PM
Quote:
Originally Posted by MechEng
Good afternoon,
I am working on finding the length of Archimedes Spiral
$r=\theta$
for... $0\leq\theta\leq2\pi$.
I think I may be doing something wrong. This is what I'm getting:
$r=\theta$
$\displaystyle\huge\frac{dr}{d\theta}=1$
$\displaystyle\int_{0}^{2\pi}\sqrt{r^2+\left(\frac{ dr}{d\theta}\right)^2}\ d\theta$
Shouldn't you have been working from the above ?
I have evaluated this to:
$\displaystyle\frac{\theta}{2}\sqrt{\theta^2-1}-\frac{ln(\theta+\sqrt{\theta^2-1}}{2}|_{0}^{2\pi}$
When I try to wrap this up by plugging in my terminals... I get a mess. Is this right?
$\displaystyle\pi\sqrt{(2\pi)^2-1}-\frac{ln(\2\pi+\sqrt{(2\pi)^2-1})}{2}$
$\displaystyle\huge\int_{0}^{2{\pi}}\sqrt{r^2+1^2}\ d\theta=\int_{0}^{2{\pi}}\sqrt{1+\theta^2}\ d\theta$
Working through the integration....
if you draw a right-angled triangle, perpendicular sides x and 1,
then the hypotenuse length is
$\sqrt{1+x^2}$
Hence.... $cos\theta=\frac{1}{\sqrt{1+x^2}}\ \Rightarrow\ \sqrt{1+x^2}=sec\theta$
$x=tan\theta$
$dx=sec^2\theta\ d\theta$
$\int{\sqrt{1+x^2}}dx=\int{\sqrt{1+tan^2\theta}sec^ 2\theta\ d\theta$
$=\int{sec\theta\ sec^2\theta\ d\theta=\int{sec^3\theta}d\theta$
Integration by parts...
$u=sec\theta,\ dv=sec^2\theta\ d\theta$
$\Rightarrow\ du=sec\theta\ tan\theta,\ v=tan\theta$
$uv-\int{v}du=sec\theta\ tan\theta-\int{sec\theta\ tan^2\theta}d\theta=sec\theta\ tan\theta-\int{sec\theta\left(sec^2\theta-1\right)d\theta$
$=sec\theta\ tan\theta-\int{sec^3\theta}d\theta+\int{sec\theta}d\theta$
$2\int{sec^3\theta}d\theta=sec\theta\ tan\theta+\int{sec\theta}d\theta$
$=sec\theta\ tan\theta+ln|sec\theta+tan\theta|$
$\int{sec^3\theta}=\frac{1}{2}\left(sec\theta\ tan\theta+ln|sec\theta+tan\theta|\right)$
$=\frac{1}{2}\left(x\sqrt{1+x^2}+ln|\sqrt{1+x^2}+x| \right)$
Rewrite using $\theta$ instead of x and evaluate using the limits.
• Aug 11th 2010, 06:46 AM
MechEng
...yep. I'm not sure how I wound up with
$\displaystyle\int_{0}^{2\pi}\sqrt{r^2-\left(\frac{dr}{d\theta}\right)^2}\ d\theta$
VS.
$\displaystyle\int_{0}^{2\pi}\sqrt{r^2 + \left(\frac{dr}{d\theta}\right)^2}\ d\theta$
I think I may have been looking at two different formulas at once, as they are all listed in the chapter summary. Since area formulas are genereally subtracting something from something else, that is the only explanation I can produce.
I thank you once again, Sir.
• Aug 11th 2010, 07:15 AM
MechEng
Anyway... Finishing this one up...
For $0\leq\theta\leq2\pi$...
$\displaystyle\frac{\left(2\pi\sqrt{1+2\pi^2}+ln|\s qrt{1+2\pi^2}+2\pi|\right)}{2}-\frac{\left(0\sqrt{1+0^2}+ln|\sqrt{1+0^2}+0|\right )}{2}$
$\displaystyle\frac{\left(2\pi\sqrt{1+2\pi^2}+ln|\s qrt{1+2\pi^2}+2\pi|\right)}{2}$
Is this a reasonable answer for this problem?
• Aug 11th 2010, 12:34 PM
Quote:
Originally Posted by MechEng
Anyway... Finishing this one up...
For $0\leq\theta\leq2\pi$...
$\displaystyle\frac{\left(2\pi\sqrt{1+(2\pi)^2}+ln| \sqrt{1+(2\pi)^2}+2\pi|\right)}{2}-\frac{\left(0\sqrt{1+0^2}+ln|\sqrt{1+0^2}+0|\right )}{2}$
$\displaystyle\frac{\left(2\pi\sqrt{1+4\pi^2}+ln|\s qrt{1+4\pi^2}+2\pi|\right)}{2}$
Is this a reasonable answer for this problem?
Looks good to me.
Be careful when squaring, parentheses helps.
Lastly, you may evaluate the final expression.
|
{"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": 0, "img_math": 0, "codecogs_latex": 38, "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": 0.9021833539009094, "perplexity": 1539.6839189808986}, "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-2017-39/segments/1505818687766.41/warc/CC-MAIN-20170921115822-20170921135822-00447.warc.gz"}
|
http://philpapers.org/s/Joseph%20S.%20Miller
|
## Works by Joseph S. Miller
18 found
Sort by:
1. Uri Andrews, Peter Gerdes & Joseph S. Miller (2014). The Degrees of Bi-Hyperhyperimmune Sets. Annals of Pure and Applied Logic 165 (3):803-811.
We study the degrees of bi-hyperhyperimmune sets. Our main result characterizes these degrees as those that compute a function that is not dominated by any ∆02 function, and equivalently, those that compute a weak 2-generic. These characterizations imply that the collection of bi-hhi Turing degrees is closed upwards.
My bibliography
Export citation
2. Laurent Bienvenu, Rupert Hölzl, Joseph S. Miller & André Nies (2014). Denjoy, Demuth and Density. Journal of Mathematical Logic 14 (1):1450004.
My bibliography
Export citation
3. Laurent Bienvenu & Joseph S. Miller (2012). Randomness and Lowness Notions Via Open Covers. Annals of Pure and Applied Logic 163 (5):506-518.
My bibliography
Export citation
My bibliography
Export citation
5. Noam Greenberg & Joseph S. Miller (2009). Lowness for Kurtz Randomness. Journal of Symbolic Logic 74 (2):665-678.
We prove that degrees that are low for Kurtz randomness cannot be diagonally non-recursive. Together with the work of Stephan and Yu [16], this proves that they coincide with the hyperimmune-free non-DNR degrees, which are also exactly the degrees that are low for weak 1-genericity. We also consider Low(M, Kurtz), the class of degrees a such that every element of M is a-Kurtz random. These are characterised when M is the class of Martin-Löf random, computably random, or Schnorr random reals. (...)
My bibliography
Export citation
6. Joseph S. Miller (2009). The K -Degrees, Low for K Degrees,and Weakly Low for K Sets. Notre Dame Journal of Formal Logic 50 (4):381-391.
We call A weakly low for K if there is a c such that $K^A(\sigma)\geq K(\sigma)-c$ for infinitely many σ; in other words, there are infinitely many strings that A does not help compress. We prove that A is weakly low for K if and only if Chaitin's Ω is A-random. This has consequences in the K-degrees and the low for K (i.e., low for random) degrees. Furthermore, we prove that the initial segment prefix-free complexity of 2-random reals is infinitely (...)
My bibliography
Export citation
7. Rod Downey, Noam Greenberg & Joseph S. Miller (2008). The Upward Closure of a Perfect Thin Class. Annals of Pure and Applied Logic 156 (1):51-58.
There is a perfect thin class whose upward closure in the Turing degrees has full measure . Thus, in the Muchnik lattice of classes, the degree of 2-random reals is comparable with the degree of some perfect thin class. This solves a question of Simpson [S. Simpson, Mass problems and randomness, Bulletin of Symbolic Logic 11 1–27].
My bibliography
Export citation
8. Verónica Becher, Santiago Figueira, Serge Grigorieff & Joseph S. Miller (2006). Randomness and Halting Probabilities. Journal of Symbolic Logic 71 (4):1411 - 1430.
We consider the question of randomness of the probability ΩU[X] that an optimal Turing machine U halts and outputs a string in a fixed set X. The main results are as follows: ΩU[X] is random whenever X is $\Sigma _{n}^{0}$-complete or $\Pi _{n}^{0}$-complete for some n ≥ 2. However, for n ≥ 2, ΩU[X] is not n-random when X is $\Sigma _{n}^{0}$ or $\Pi _{n}^{0}$ Nevertheless, there exists $\Delta _{n+1}^{0}$ sets such that ΩU[X] is n-random. There are $\Delta _{2}^{0}$ sets (...)
My bibliography
Export citation
9. Peter Cholak, Noam Greenberg & Joseph S. Miller (2006). Uniform Almost Everywhere Domination. Journal of Symbolic Logic 71 (3):1057 - 1072.
We explore the interaction between Lebesgue measure and dominating functions. We show, via both a priority construction and a forcing construction, that there is a function of incomplete degree that dominates almost all degrees. This answers a question of Dobrinen and Simpson, who showed that such functions are related to the proof-theoretic strength of the regularity of Lebesgue measure for Gδ sets. Our constructions essentially settle the reverse mathematical classification of this principle.
My bibliography
Export citation
10. Barbara F. Csima, Rod Downey, Noam Greenberg, Denis R. Hirschfeldt & Joseph S. Miller (2006). Every 1-Generic Computes a Properly 1-Generic. Journal of Symbolic Logic 71 (4):1385 - 1393.
A real is called properly n-generic if it is n-generic but not n+1-generic. We show that every 1-generic real computes a properly 1-generic real. On the other hand, if m > n ≥ 2 then an m-generic real cannot compute a properly n-generic real.
My bibliography
Export citation
11. Rodney G. Downey, Carl Jockusch & Joseph S. Miller (2006). On Self-Embeddings of Computable Linear Orderings. Annals of Pure and Applied Logic 138 (1):52-76.
The Dushnik–Miller Theorem states that every infinite countable linear ordering has a nontrivial self-embedding. We examine computability-theoretical aspects of this classical theorem.
My bibliography
Export citation
12. Wolfgang Merkle, Joseph S. Miller, André Nies, Jan Reimann & Frank Stephan (2006). Kolmogorov–Loveland Randomness and Stochasticity. Annals of Pure and Applied Logic 138 (1):183-210.
An infinite binary sequence X is Kolmogorov–Loveland random if there is no computable non-monotonic betting strategy that succeeds on X in the sense of having an unbounded gain in the limit while betting successively on bits of X. A sequence X is KL-stochastic if there is no computable non-monotonic selection rule that selects from X an infinite, biased sequence.One of the major open problems in the field of effective randomness is whether Martin-Löf randomness is the same as KL-randomness. Our first (...)
My bibliography
Export citation
13. Joseph S. Miller & André Nies (2006). Randomness and Computability: Open Questions. Bulletin of Symbolic Logic 12 (3):390-410.
My bibliography
Export citation
14. Rod Downey, Denis R. Hirschfeldt, Joseph S. Miller & André Nies (2005). Relativizing Chaitin's Halting Probability. Journal of Mathematical Logic 5 (02):167-192.
My bibliography
Export citation
15. Joseph S. Miller & Lawrence S. Moss (2005). The Undecidability of Iterated Modal Relativization. Studia Logica 79 (3):373 - 407.
In dynamic epistemic logic and other fields, it is natural to consider relativization as an operator taking sentences to sentences. When using the ideas and methods of dynamic logic, one would like to iterate operators. This leads to iterated relativization. We are also concerned with the transitive closure operation, due to its connection to common knowledge. We show that for three fragments of the logic of iterated relativization and transitive closure, the satisfiability problems are fi1 11–complete. Two of these fragments (...)
My bibliography
Export citation
16. Joseph S. Miller (2004). Degrees of Unsolvability of Continuous Functions. Journal of Symbolic Logic 69 (2):555 - 584.
We show that the Turing degrees are not sufficient to measure the complexity of continuous functions on [0, 1]. Computability of continuous real functions is a standard notion from computable analysis. However, no satisfactory theory of degrees of continuous functions exists. We introduce the continuous degrees and prove that they are a proper extension of the Turing degrees and a proper substructure of the enumeration degrees. Call continuous degrees which are not Turing degrees non-total. Several fundamental results are proved: a (...)
My bibliography
Export citation
17. Joseph S. Miller (2004). Every 2-Random Real is Kolmogorov Random. Journal of Symbolic Logic 69 (3):907-913.
We study reals with infinitely many incompressible prefixes. Call $A \in 2^{\omega}$ Kolmogorot random if $(\exists^{\infty}n) C(A \upharpoonright n) \textgreater n - \mathcal{O}(1)$ , where C denotes plain Kolmogorov complexity. This property was suggested by Loveland and studied by $Martin-L\ddot{0}f$ , Schnorr and Solovay. We prove that 2-random reals are Kolmogorov random. Together with the converse-proved by Nies. Stephan and Terwijn [11]-this provides a natural characterization of 2-randomness in terms of plain complexity. We finish with a related characterization of 2-randomness.
|
{"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": 0, "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": 0.9719340205192566, "perplexity": 2134.8363795117907}, "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-2015-18/segments/1429246659254.83/warc/CC-MAIN-20150417045739-00265-ip-10-235-10-82.ec2.internal.warc.gz"}
|
https://openreview.net/forum?id=HkeyZhC9F7
|
## Learning Heuristics for Automated Reasoning through Reinforcement Learning
27 Sep 2018 (modified: 21 Dec 2018)ICLR 2019 Conference Blind SubmissionReaders: Everyone
• Abstract: We demonstrate how to learn efficient heuristics for automated reasoning algorithms through deep reinforcement learning. We focus on backtracking search algorithms for quantified Boolean logics, which already can solve formulas of impressive size - up to 100s of thousands of variables. The main challenge is to find a representation of these formulas that lends itself to making predictions in a scalable way. For challenging problems, the heuristic learned through our approach reduces execution time by a factor of 10 compared to the existing handwritten heuristics.
• Keywords: reinforcement learning, deep learning, logics, formal methods, automated reasoning, backtracking search, satisfiability, quantified Boolean formulas
• TL;DR: RL finds better heuristics for automated reasoning algorithms.
10 Replies
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.905809760093689, "perplexity": 2224.8188882311624}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "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-2020-45/segments/1603107882581.13/warc/CC-MAIN-20201024110118-20201024140118-00514.warc.gz"}
|
https://meridian.allenpress.com/iosc/article/1977/1/517/138445/MICROBIAL-RESPONSES-AFTER-TWO-EXPERIMENTAL-OIL
|
ABSTRACT
Three large transite-sided enclosures, constructed in a tidal salt marsh in southeastern Virginia, were utilized to evaluate the effects of crude oil spillage on selected microbial populations. Unweathered Louisiana crude oil was spilled in one enclosure, artificially weathered South Louisiana crude in another, and the third served as a control. Each enclosure was constructed so as to allow unhampered exchange with tidal flow on the tidal creek side.
Heterotrophic bacteria and fungi, chitinolytic, cellulytic and petroleum-degrading bacterial populations from the tidal creek, and sediments in intertidal, mid- and back-marsh zones were enumerated at selected intervals following the oil spills. Dominant petroleum-degrading and heterotrophic bacterial isolates were selected for taxonomic grouping.
Within several days following the spills, the levels of petroleum-degrading bacteria rose by several orders of magnitude relative to the control enclosure. This differential has been maintained for approximately one year. Plots of the ratio of oil-degrading to heterotrophic bacteria reveal enhancement of the petroleum degrading component of the heterotrophic population. Mean levels of chitinolytic, cellulytic, heterotrophic bacteria and fungi were not statistically different in the oil and control enclosures. The potential significance of these observations is discussed.
This content is only available as a PDF.
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8401466608047485, "perplexity": 11713.14192702288}, "config": {"markdown_headings": false, "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-2021-43/segments/1634323585424.97/warc/CC-MAIN-20211021133500-20211021163500-00660.warc.gz"}
|
https://community.plm.automation.siemens.com/t5/Discussion-Forum-NX-Manufacturing/NX-10-0-3-Fix-contour/td-p/327008
|
Cancel
Showing results for
Did you mean:
# NX 10.0.3 Fix contour
Solution Partner Builder
Dear all
I am using NX 10.0.3 . I create fix contour operation . use step over on part at 5 mm . When I generate tool path out put has space error (see in attach file). This is error of program ?
thank you
2 REPLIES
# Re: NX 10.0.3 Fix contour
Gears Esteemed Contributor
This is no error, since you selected "step on part", which takes the draft angle of faces into account.
If you want equally spaced steps despite of the draft angle of the faces, you need to use "step on plane".
Stefan Pendl, Systemmanager CAx, HAIDLMAIR GmbH
Production: NX10.0.3, VERICUT 8.1, FBM, MRL 3.1.7 | TcUA 10.1 MP7 Patch 0 (10.1.7.0) | TcVis 11.4
Development: C (ITK), .NET, Tcl/Tk Testing: NX12.0 | AWC 3.4 Preparing: NX12.0
Employees of the customers, together we are strong
How to Get the Most from Your Signature in the Community
NX Customization - Best Practice Guide
# Re: NX 10.0.3 Fix contour
VIP
There is proabably some point alont the passes where they are going across a steep area, so they are moved closer together to maintain the stepover along the steep wall. But since zig and zig-zag patterns have parallel passes, the passes bunch together closer than this on the near flat areas.
Mark Rief
Retired Siemens
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8350358605384827, "perplexity": 26114.501676270353}, "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-2018-30/segments/1531676590169.5/warc/CC-MAIN-20180718115544-20180718135544-00337.warc.gz"}
|
http://mathematica.stackexchange.com/questions/24639/strange-behavior-of-integrate/24640
|
Strange behavior of Integrate
I'm trying to calculate the following integral using Mathematica 9.0.1.0
a11=Integrate[Abs[Sin[b+x]],{x,0,2*\[Pi]}]
This should be a simple problem; however, it took Mathematica a very long time to obtain the answer, which is 4. I asked a colleague to do it with Maple, the answer is obtained instantly. I thought may be this has something to do with the fact that Mathematica treats everthing as Complex value, so I rewrote the programm as
a1=Integrate[Abs[Sin[b+x]],{x,0,2*\[Pi]},Assumptions->{Element[{b,x},Reals]}]
Unfortunately, it took Mathematica even more time to run this command. What's more unfortunate is that the obtained answer is wrong:
4 Abs[Sin[b]] Cot[b]
Does anybody know what's wrong here?
-
It's even more unfortunate that Integrate[Abs[Sin[b + x]], {x, 0, 2 Pi}, Assumptions -> {b \[Element] Reals}] returns 0 for me. – b.gatessucks May 4 '13 at 14:38
@b.gatessucks. I tried your way, it returns 0, too. Is this a BUG? – user2256793 May 4 '13 at 14:48
Yes, I think so. – b.gatessucks May 4 '13 at 14:56
It does seem to be one. I've tagged appropriately. (For fun, see what happens if you use assumptions like b > 0 or b < 0, or some finite interval.) – Ｊ. Ｍ. May 4 '13 at 15:17
FullSimplify@ Integrate[Abs@Sin[b + x] , {x, 0, 2 Pi}, Assumptions -> {0 < b < 2 Pi}]
(*
4
*)
-
In[77]:= \$Version
Out[77]= "9.0 for Microsoft Windows (64-bit) (January 25, 2013)"
In[73]:= Timing[All = Integrate[Abs[Sin[b + x]], {x, 0, 2*\[Pi]}]]
Out[73]= {81.073720, 4}
In[75]:= Timing[
FullSimplify@
Integrate[Abs@Sin[b + x], {x, 0, 2 Pi},
Assumptions -> {0 < b < 2 Pi}]]
(*4*)
Out[75]= {1.404009, 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": 0.31614717841148376, "perplexity": 2299.6397981740574}, "config": {"markdown_headings": false, "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-2014-23/segments/1405997879037.61/warc/CC-MAIN-20140722025759-00099-ip-10-33-131-23.ec2.internal.warc.gz"}
|
https://hal.inria.fr/inria-00074300
|
# The average case analysis of algorithms : Saddle Point Asymptotics
1 ALGO - Algorithms
Inria Paris-Rocquencourt
Abstract : This report is part of a series whose aim is to present in a synthetic way the major methods of analytic combinatorics'' needed in the average--case analysis of algorithms. It reviews the use of the saddle point method in order to estimate asymptotically coefficients of fast growing generating functions. The applications treated concern the enumeration of set partitions and integer partitions, permutations with cycle restrictions, increasing subsequences, as well as distribution estimates when large powers are involved.
Type de document :
Rapport
[Research Report] RR-2376, INRIA. 1994
Domaine :
https://hal.inria.fr/inria-00074300
Contributeur : Rapport de Recherche Inria <>
Soumis le : mercredi 24 mai 2006 - 15:00:34
Dernière modification le : vendredi 25 mai 2018 - 12:02:02
Document(s) archivé(s) le : mardi 12 avril 2011 - 16:26:34
### Identifiants
• HAL Id : inria-00074300, version 1
### Citation
Philippe Flajolet, Robert Sedgewick. The average case analysis of algorithms : Saddle Point Asymptotics. [Research Report] RR-2376, INRIA. 1994. 〈inria-00074300〉
### Métriques
Consultations de la notice
## 107
Téléchargements de fichiers
|
{"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": 0.6355628371238708, "perplexity": 6243.625365012452}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "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-2018-26/segments/1529267864740.48/warc/CC-MAIN-20180622162604-20180622182604-00221.warc.gz"}
|
http://mathhelpforum.com/algebra/146268-solving-word-problems-equations.html
|
# Thread: Solving Word Problems With Equations
1. ## Solving Word Problems With Equations
Another word problem.
David flew 300km on a commuter plane, then 2000km on a passenger jet. The passenger jet flew twice as fast as the commuter plane. The total flying time for the journey was 3.25 hours. What was the speed of each plane, in kilometers per hour?
2. Originally Posted by larry21
Another word problem.
David flew 300km on a commuter plane, then 2000km on a passenger jet. The passenger jet flew twice as fast as the commuter plane. The total flying time for the journey was 3.25 hours. What was the speed of each plane, in kilometers per hour?
Remember $d=rt \iff t=\frac{d}{r}$
Let $r$ be the speed of the commuter plane then $2r$ is the speed of the jet then
$\frac{300}{r}+\frac{2000}{2r}=3.25$
|
{"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": 0, "img_math": 0, "codecogs_latex": 4, "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": 0.8328163027763367, "perplexity": 1727.4906450555877}, "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-2017-34/segments/1502886116921.70/warc/CC-MAIN-20170823000718-20170823020718-00537.warc.gz"}
|
https://www.autoitscript.com/forum/topic/55623-access-frame-with-no-name/
|
# Access Frame with no Name
## Recommended Posts
I am having problems on how to click a text link in a frame with no name.
IE Builder gave me the following information:
The frame with index number 9 is the one that contains the link that I want to click.
I hope Dale could help me.
##### Share on other sites
I found this code below from another thread to diagnose my problem:
$oFrames = _IETagNameGetCollection ($oIE, "frame")
ConsoleWrite("Frame Count: " & @extended & @CR)
$i = 0$sFrameInfo = ""
For $oFrame In$oFrames
$sFrameInfo &= "===============" & @CR$sFrameInfo &= "Frame: " & $i & @CR$sFrameInfo &= "Name: " & $oFrame.name & @CR$sFrameInfo &= "SRC: " & $oFrame.src & @CR$sFrameInfo &= ">>>>><HTML START><<<<<" & @CR & $oFrame.innerHTML & @CR$sFrameInfo &= ">>>>><HTML END><<<<<" & @CR
$i += 1 Next$sFrameInfo &= "==============="
$oFrame = _IEFrameGetCollection($oIE, $index) Dale Edit: Typo Edited by DaleHohm Free Internet Tools: DebugBar, AutoIt IE Builder, HTTP UDF, MODIV2, IE Developer Toolbar, IEDocMon, Fiddler, HTML Validator, WGet, curl Automate input type=file (Related) SciTe Debug mode - it's magic: #AutoIt3Wrapper_run_debug_mode=Y Doesn't work needs to be ripped out of the troubleshooting lexicon. It means that what you tried did not produce the results you expected. It begs the questions 1) what did you try?, 2) what did you expect? and 3) what happened instead? Reproducer: a small (the smallest?) piece of stand-alone code that demonstrates your trouble #### Share this post ##### Link to post ##### Share on other sites Thanks Dale, I've already tried that but the problem is I cannot access the contents of frame with$index = 1. Maybe because each of the frame content is in PHP. This is the only source code that the IE Builder is giving me.
<FRAME name=topFrame marginWidth=1 marginHeight=1 src="navBar.php?type=project&nav= > Test Plan Metrics" noResize scrolling=no><FRAMESET border=0 frameSpacing=0 frameBorder=NO cols=30%,*><FRAME src="metrics/metricsLeft.php" scrolling=yes><FRAME name=mainFrame src="metrics/metricsSelection.php"></FRAMESET>
What do you think is the problem? Thanks a lot.
##### Share on other sites
Try this:
$index = 1 ; 0 = topFrame, 2 = mainFrame$oFrame = _IEFrameGetCollection($oIE,$index)
ConsoleWrite( _IEDocReadHTML($oFrame) & @CR) the example your have is not a good one because it is enumerating the frames as "tags" rather than as "windows" Dale Free Internet Tools: DebugBar, AutoIt IE Builder, HTTP UDF, MODIV2, IE Developer Toolbar, IEDocMon, Fiddler, HTML Validator, WGet, curl Automate input type=file (Related) SciTe Debug mode - it's magic: #AutoIt3Wrapper_run_debug_mode=Y Doesn't work needs to be ripped out of the troubleshooting lexicon. It means that what you tried did not produce the results you expected. It begs the questions 1) what did you try?, 2) what did you expect? and 3) what happened instead? Reproducer: a small (the smallest?) piece of stand-alone code that demonstrates your trouble #### Share this post ##### Link to post ##### Share on other sites I've already tried that also Dale, anyway I tried once more but same result: #include <IE.au3>$oIE = _IECreate("https://www.xxxxxx.com/metrics/metricsFrameSet.php?nav=%20>%20Test%20Plan%20Metrics")
$index = 1; 0 = topFrame, 2 = mainFrame$oFrame = _IEFrameGetCollection($oIE,$index)
ConsoleWrite( _IEDocReadHTML($oFrame) & @CR) Got an error: C:\Program Files\AutoIt3\beta\Include\IE.au3 (2214) : ==> The requested action with this object has failed.: Return$o_object.document.documentElement.outerHTML
Return \$o_object.document^ ERROR
## Create an account
Register a new account
• ### Recently Browsing 0 members
×
• Wiki
• Back
• #### Beta
• Git
• FAQ
• Our Picks
×
• Create New...
|
{"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": 0, "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": 0.9300522208213806, "perplexity": 28572.85177494869}, "config": {"markdown_headings": true, "markdown_code": false, "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-2021-17/segments/1618039546945.85/warc/CC-MAIN-20210421161025-20210421191025-00362.warc.gz"}
|
https://networks.skewed.de/net/unicodelang
|
# Netzschleuder network catalogue, repository and centrifuge
Problems with this dataset? Open an issue.
You may also take a look at the source code.
The network in this dataset can be loaded directly from graph-tool with:
import graph_tool.all as gt
g = gt.collection.ns["unicodelang"]
# unicodelang — Languages spoken by country (2015)
Description
A bipartite network of languages and the countries in which they are spoken, as estimated by Unicode. Edges are weighted by the proportion of the given country's population that is literate in a particular language.1
1. Description obtained from the ICON project.
Tags
Informational Relatedness Weighted
Citation
Upstream URL OK
http://konect.cc/networks/unicodelang
Networks
Tip: hover your mouse over a table header to obtain a legend.
Name Nodes Edges $\left<k\right>$ $\sigma_k$ $\lambda_h$ $\tau$ $r$ $c$ $\oslash$ $S$ Kind Mode NPs EPs gt GraphML GML csv
unicodelang 868 1,255 2.89 6.73 7.88 25.78 -0.17 0.00 8 0.99 Undirected Bipartite meta weight 20 KiB 26 KiB 24 KiB 19 KiB
Ridiculograms
|
{"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": 0.7465106248855591, "perplexity": 5722.356344665454}, "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-2022-49/segments/1669446711016.32/warc/CC-MAIN-20221205100449-20221205130449-00215.warc.gz"}
|
https://www.aimsciences.org/article/doi/10.3934/cpaa.2004.3.291
|
# American Institute of Mathematical Sciences
• Previous Article
Existence of the global attractor for weakly damped, forced KdV equation on Sobolev spaces of negative index
• CPAA Home
• This Issue
• Next Article
Effects of small viscosity and far field boundary conditions for hyperbolic systems
June 2004, 3(2): 291-300. doi: 10.3934/cpaa.2004.3.291
## On the existence of quasi periodic and almost periodic solutions of neutral functional differential equations
1 Department of Mathematics, Hanoi University of Science, 334 Nguyen Trai, Hanoi, Vietnam 2 Department of Mathematics, Hanoi University of Science, 334 Nguyen Trai, Hanoi, Vietnam
Received January 2003 Revised January 2004 Published March 2004
This paper is concerned with the existence of almost periodic solutions of neutral functional differential equations of the form $\frac{d}{dt}Dx_t = Lx_t+f(t)$, where $D,$ $L$ are bounded linear operators from $\mathcal C$ :$= C([-r, \quad 0],\quad \mathbb C^n )$ to $\mathbb C^n$, $f$ is an almost (quasi) periodic function. We prove that if the set of imaginary solutions of the characteristic equations is bounded and the equation has a bounded, uniformly continuous solution, then it has an almost (quasi) periodic solution with the same set of Fourier exponents as $f$.
Citation: Nguyen Minh Man, Nguyen Van Minh. On the existence of quasi periodic and almost periodic solutions of neutral functional differential equations. Communications on Pure & Applied Analysis, 2004, 3 (2) : 291-300. doi: 10.3934/cpaa.2004.3.291
[1] Yongkun Li, Pan Wang. Almost periodic solution for neutral functional dynamic equations with Stepanov-almost periodic terms on time scales. Discrete & Continuous Dynamical Systems - S, 2017, 10 (3) : 463-473. doi: 10.3934/dcdss.2017022 [2] Yingte Sun, Xiaoping Yuan. Quasi-periodic solution of quasi-linear fifth-order KdV equation. Discrete & Continuous Dynamical Systems, 2018, 38 (12) : 6241-6285. doi: 10.3934/dcds.2018268 [3] Defei Zhang, Ping He. Functional solution about stochastic differential equation driven by $G$-Brownian motion. Discrete & Continuous Dynamical Systems - B, 2015, 20 (1) : 281-293. doi: 10.3934/dcdsb.2015.20.281 [4] Osama Moaaz, Omar Bazighifan. Oscillation criteria for second-order quasi-linear neutral functional differential equation. Discrete & Continuous Dynamical Systems - S, 2020, 13 (9) : 2465-2473. doi: 10.3934/dcdss.2020136 [5] Changrong Zhu, Bin Long. The periodic solutions bifurcated from a homoclinic solution for parabolic differential equations. Discrete & Continuous Dynamical Systems - B, 2016, 21 (10) : 3793-3808. doi: 10.3934/dcdsb.2016121 [6] Nicola Guglielmi, Christian Lubich. Numerical periodic orbits of neutral delay differential equations. Discrete & Continuous Dynamical Systems, 2005, 13 (4) : 1057-1067. doi: 10.3934/dcds.2005.13.1057 [7] Xiao Wang, Zhaohui Yang, Xiongwei Liu. Periodic and almost periodic oscillations in a delay differential equation system with time-varying coefficients. Discrete & Continuous Dynamical Systems, 2017, 37 (12) : 6123-6138. doi: 10.3934/dcds.2017263 [8] John A. D. Appleby, John A. Daniels. Exponential growth in the solution of an affine stochastic differential equation with an average functional and financial market bubbles. Conference Publications, 2011, 2011 (Special) : 91-101. doi: 10.3934/proc.2011.2011.91 [9] Xianhua Huang. Almost periodic and periodic solutions of certain dissipative delay differential equations. Conference Publications, 1998, 1998 (Special) : 301-313. doi: 10.3934/proc.1998.1998.301 [10] Tomás Caraballo, David Cheban. Almost periodic and almost automorphic solutions of linear differential equations. Discrete & Continuous Dynamical Systems, 2013, 33 (5) : 1857-1882. doi: 10.3934/dcds.2013.33.1857 [11] Nguyen Thieu Huy, Ngo Quy Dang. Dichotomy and periodic solutions to partial functional differential equations. Discrete & Continuous Dynamical Systems - B, 2017, 22 (8) : 3127-3144. doi: 10.3934/dcdsb.2017167 [12] Chunhong Li, Jiaowan Luo. Stochastic invariance for neutral functional differential equation with non-lipschitz coefficients. Discrete & Continuous Dynamical Systems - B, 2019, 24 (7) : 3299-3318. doi: 10.3934/dcdsb.2018321 [13] Jing Li, Boling Guo, Lan Zeng, Yitong Pei. Global weak solution and smooth solution of the periodic initial value problem for the generalized Landau-Lifshitz-Bloch equation in high dimensions. Discrete & Continuous Dynamical Systems - B, 2020, 25 (4) : 1345-1360. doi: 10.3934/dcdsb.2019230 [14] Burcu Gürbüz. A computational approximation for the solution of retarded functional differential equations and their applications to science and engineering. Journal of Industrial & Management Optimization, 2021 doi: 10.3934/jimo.2021069 [15] Tomás Caraballo, Gábor Kiss. Attractivity for neutral functional differential equations. Discrete & Continuous Dynamical Systems - B, 2013, 18 (7) : 1793-1804. doi: 10.3934/dcdsb.2013.18.1793 [16] Hernán R. Henríquez, Claudio Cuevas, Alejandro Caicedo. Asymptotically periodic solutions of neutral partial differential equations with infinite delay. Communications on Pure & Applied Analysis, 2013, 12 (5) : 2031-2068. doi: 10.3934/cpaa.2013.12.2031 [17] Miguel V. S. Frasson, Patricia H. Tacuri. Asymptotic behaviour of solutions to linear neutral delay differential equations with periodic coefficients. Communications on Pure & Applied Analysis, 2014, 13 (3) : 1105-1117. doi: 10.3934/cpaa.2014.13.1105 [18] Changchun Liu, Hui Tang. Existence of periodic solution for a Cahn-Hilliard/Allen-Cahn equation in two space dimensions. Evolution Equations & Control Theory, 2017, 6 (2) : 219-237. doi: 10.3934/eect.2017012 [19] Benjamin B. Kennedy. A periodic solution with non-simple oscillation for an equation with state-dependent delay and strictly monotonic negative feedback. Discrete & Continuous Dynamical Systems - S, 2020, 13 (1) : 47-66. doi: 10.3934/dcdss.2020003 [20] Ernest Fontich, Rafael de la Llave, Yannick Sire. A method for the study of whiskered quasi-periodic and almost-periodic solutions in finite and infinite dimensional Hamiltonian systems. Electronic Research Announcements, 2009, 16: 9-22. doi: 10.3934/era.2009.16.9
2020 Impact Factor: 1.916
|
{"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": 0, "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": 0.5971670746803284, "perplexity": 3478.673954107296}, "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-2021-43/segments/1634323588398.42/warc/CC-MAIN-20211028162638-20211028192638-00069.warc.gz"}
|
https://www.physicsforums.com/threads/how-do-i-prove-xy-x-y.711403/
|
# How do I prove |xy| = |x| * |y|?
1. Sep 19, 2013
### athena810
1. The problem statement, all variables and given/known data
Prove:
|xy| = |x| * |y|?
2. Relevant equations
|x| = sqrt(x^2)
3. The attempt at a solution
(|xy|)^2 = (|x| * |y|)^2
x^2y^2 = x^2 y^2
---I think this is incorrect though. Really, I don't understand proofs and the concept of proofing.
2. Sep 19, 2013
### Office_Shredder
Staff Emeritus
One way you can do it is to break it down into cases
Case 1: If either x or y is zero....
Case 2: If x > 0 and y > 0
Case 3: If x > 0 and y < 0
etc. This is how things with absolute values are usually handled.
Alternatively, what you have done is very close to being complete (and pretty clever). Starting from x2 y2 = x2 y 2 you can get to (|xy|)2= (|x|*|y|)2. Now, in general if I have a2 = b2 then I know that a = b OR a = -b. So you have that |xy| = |x|*|y| OR |xy| = -|x|*|y|. You should be able to discount the second one fairly easily
3. Sep 19, 2013
### epenguin
You don't understand proofs? You have never seen any mathematical proof?
Forget those attempts.
The truth statement itself is, I hope, blindingly obvious. But that's not enough for mathematicians. What you have to do, what they are asking you to do, is to take the definition of |x| ( i.e. |anything|) and show that the statement follows logically.
Actually there is more that needs defining. In principle you might need to define * but I don't think you are being asked to go that far back. You surely have learnt some rules about things like what is x* -y , -x * -y . You are required to combine these with the definition of | | to prove the statement.
4. Sep 19, 2013
### athena810
If I do it this way, then do I just say something like:
If x, y = 0, then 0*0 = 0*0?
How do I know that it's not -a = b, or does it not matter which one I make negative?
As for that case, in order to disprove it, do I just say that I can't sqrt negatives? Like: "sqrt(-b) is not a Real number."?
Thanks
I've seen proofs, and I kind of understand that it's basically stating the obvious using theorems and whatever. I've done simpler proofs like proving a^2 > a if a > 1 but I'm not sure what to do with | |.
5. Sep 19, 2013
### vela
Staff Emeritus
You're right. It's not correct. A major mistake is that you're starting off using what you're trying to prove. In other words, don't start off the proof with |xy|=|x||y|.
One common technique is to start with one side and then get to the other, e.g. $\lvert xy\rvert = \sqrt{(xy)^2} = \cdots = \lvert x\rvert\lvert y\rvert$. For each step, you should be able to state a reason to justify that step. For example, you might justify writing $\lvert xy\rvert = \sqrt{(xy)^2}$ as using the definition of the absolute value (I'm assuming that's how it's defined in your class). You can justify the step $\sqrt{(xy)^2} = \sqrt{x^2 y^2}$ based on the property of real numbers, and so on.
6. Sep 19, 2013
### athena810
So then it is:
|xy|=|xy|
(|xy|)^2 = (|xy|)^2
(|xy|)^2 = |x|^2 * |y|^2
sqrt(|xy|^2) = sqrt(|x|^2) * sqrt(|y|^2)
|xy| = |x| * |y|
Is this correct?
7. Sep 19, 2013
### Avodyne
No, this is not correct.
First of all, what definition of |x| is given in your text (or by your instructor)? I very much doubt that it is |x|=√x2, which has all sorts of difficulties. The usual definition is |x|=x if x>0, |x|=-x if x<0, and |x|=0 if x=0.
So a valid proof would start out something like this.
If x=0, then |x|=0 by definition, and xy=0 by the multiplication property of zero. If xy=0, then |xy|=0 by definition. Also, if |x|=0, then |x|*|y|=0 by the multiplication property of zero. Thus, if x=0, we have both |xy|=0 and |x|*|y|=0, and so |xy|=|x|*|y| in this case.
If y=0, swap x and y in the proof above.
Now suppose x>0 and y>0. ...
Continue through all possible cases.
Note that each step should be justified.
8. Sep 19, 2013
### epenguin
Start by stating the definition of | | .
Be a country girl! You go into relatively complicated stuff you have heard about about squares that is not the point here. (I realise that squaring does something quite reminiscent of | | , namely turning negatives into positives, but here it is not the point.)
Office_Shredder has given you the idea. But what you wrote is just not a proof.
If you said in the case x = 0, y = 0 , what does |x| equal, what does |y| equal, what thence do |x| , |y| equal, hence what does |x|*|y| equal on the one hand, on the other hand what does |x * y| equal, are these two things equal between each other? If so the theorem is true for that case. Then if you could show it was true for the two other cases, then it is true in general and you have proved the theorem.
We have called these two things x and y. Sure we could have called them a and b and the argument is no different.
I think your question meant does it matter whether you make x or y negative, or perhaps you are wondering as well as Office_Shredder's 3 cases, shouldn't there be a 4th: x negative and y positive? This sort of thing often flummoxes beginners and not-so beginners, so get it clear. Algebraic symbols are 'disponible', available, on call. They mean what we decide we want them to mean. So the point here was case 3 is the case where x and y have opposite signs. So if we say let x>0 y<0 or if OTOH we say let x<0 y>0 we are saying exactly the same thing, we have just decided differently what we meant by x and y. So you can use one or the other of those inequality pairs, it doesn't mean anything to use them both. At risk of repetition we are just in case 3 considering the case where one of x, y is a positive number and the other is a negative number and it doesn't matter which we decide to be which.
Last edited: Sep 20, 2013
9. Sep 19, 2013
### vela
Staff Emeritus
What difficulties are those? This is, in fact, how the absolute value is sometimes defined for real numbers.
10. Sep 19, 2013
### vela
Staff Emeritus
You run into a problem here because you've used the fact that |xy|=|x||y|, which is what you're supposed to be proving.
Don't square in the beginning. Just keep everything under the square root.
11. Sep 19, 2013
### athena810
It was defined the normal way with the 4 cases. Then it was like: "This theorem can also be proved in a much simpler way. Notice: √x^2 = |x|.
Also, in most of the example proofs, they didn't list the reasons why. It would list all the steps, then at the bottom be like "<this> could happen because of <this property>. Therefore <this> = <that>."
But anyway, do I write the proof in paragraph form like what you did or do I write it like 2 column geometric proofs?
So I would say:
(Case 1) x= 0, y= 0...and then be like " |a + b| = a + b= |a| + |b|"?
12. Sep 19, 2013
### athena810
So if I keep it under the radical:
...
sqrt(|xy|) = sqrt(|x| * |y|) ?
13. Sep 19, 2013
### vela
Staff Emeritus
No, again, you're using what you're trying to prove.
Last edited: Sep 20, 2013
14. Sep 20, 2013
### epenguin
I said, and I don't think anyone here will disagree, that you have to start with the definition of | |.
Actually frame this as a definition of |x| . Because of what I explained about algebraic symbolism, this also covers y, you don't need to state it separately but we will allow you to do that if it helps you.
I cannot help you further until you state a definition and when you have done it make an effort to treat at least one, any one, of the three cases that arise.
Last edited: Sep 20, 2013
15. Sep 20, 2013
### athena810
Will this work?
So definition of | |: The positive value of any real number.
Case 1: If x, y >= 0..then |x| = x, |y| = y, xy >= 0. Thus |xy| =xy = |x||y|?
Last edited: Sep 20, 2013
16. Sep 20, 2013
### HallsofIvy
Staff Emeritus
Do you have a specific definition of "The positive value of a real number". Have you ever seen a text book that gives that a the definition of absolute value?
The definition every text book I have ever seen gives is "|x|= x if $x\ge 0$, |x|= -x if x< 0".
17. Sep 20, 2013
### epenguin
OK you give an informal definition that sounds like what someone said in class explaining it to you. And maybe your memory. H of I is surprised if that is in a book. Use the book.
To be able to use definition you really need the formal one given by HofI.
This bit
Case 1: If x, y >= 0..then |x| = x, |y| = y,
is OK. The rest is all true but it doesn't seem to me a proof argument.
I suggest you do things like this by numbers so it is clear where everything comes from and fits in. I will give my version as model with which you could do the second bit.
1 Definition of |x| as per HofI. (Def 1)
Remark: use of the ≥ has reduced our cases to two not three.
2 Case 1. x ≥ 0, y ≥ 0 (condition A)
By Def 1 (1) |x| = x, |y| = y. Therefore in case 1 |x|*|y| = x * y
3 Still case 1, from condition (A), x * y ≥ 0
4 From Def 1 and 3, |x * y| = x * y
5 Two things that are equal to a third thing are equal to each other.
So the two things we found above each equal to x*y are equal to each other, i.e. |x|*|y| = |x * y|
6 Case 2, |x| ≥ 0, |y| < 0 ...
I don't say this is perfect (it is not my field) but do you see this more like a logical proof, not a handwaving?
It lays bare assumptions, e.g. 3 is I guess an assumption carried over from basic arithmetic and algebra, and line 1 of 5 is an assumed property of " = " , I think you will hear talk of "equivalence relations".
Last edited: Sep 20, 2013
18. Sep 20, 2013
### athena810
No, it was not from a textbook.
Oh, ok, I kind of understand.
Is it required that i write a reason for doing why I did what I did or are the reasons implied?
19. Sep 20, 2013
### arildno
" The rest is all true but it doesn't seem to me a proof argument."
Why not?
In cases x,y positive, we have
|x*y|=x*y=|x|*|y|, i.e identity verified.
20. Sep 20, 2013
### Avodyne
This is really a question for your instructor, but to be unambiguous the reason should be given for each step.
Also, the definition |x|=√x2 is OK provided that the symbol "√" is defined to mean the positive square root. Then, to use this definition in a proof, you would need to assume rules about square roots such as: if x≥0 and y≥0, then √(xy) = √x * √y. (If you had to prove this rule first, then the proof would probably be longer than one based on the simpler definition of |x| as x if x≥0 and -x if x<0.)
Draft saved Draft deleted
Similar Discussions: How do I prove |xy| = |x| * |y|?
|
{"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": 2, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "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": 0.858299732208252, "perplexity": 874.7588413649032}, "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-2017-51/segments/1512948519776.34/warc/CC-MAIN-20171212212152-20171212232152-00163.warc.gz"}
|
https://mathoverflow.net/questions/119115/example-of-fiber-bundle-that-is-not-a-fibration/126228
|
# Example of fiber bundle that is not a fibration
It is well-known that a fiber bundle under some mild hypothesis is a fibration, but I don't know any examples of fiber bundles which aren't (Hurewicz) fibrations (they should be weird examples, I think, because if the base space is paracompact then the bundle is a fibration).
Does anybody know an example?
Thanks!
• mathoverflow.net/questions/20442/… – Dylan Wilson Jan 17 '13 at 3:44
• It will still be a Serre fibration, in any case. – David Roberts Jan 17 '13 at 14:09
• Here's a vague sketch. Take a non-numerable cover of some necessarily non paracompact space, and take a non coboundary, G-valued Čech cocycle. Then this bundle isn't classifiable by a map to BG, as the universal bundle trivialities over a numerable cover (i.e. is numerable), and numerable covers pull back. As soon as your bundle is numerable it is a Hurewicz fibration. Now you have a chance that you'll find an example. – David Roberts Jan 17 '13 at 14:17
$\newcommand{\RR}{\mathbb{R}} \newcommand{\To}{\longrightarrow} \newcommand{\id}{\mathrm{id}}$The example described in Tom Goodwillie's answer to a related mathoverflow question essentially solves this question. Specifically, Tom defines an orientable, non-trivial, real line bundle $L$ over a contractible space $X$. The principal $GL_1^+(\RR)$-bundle — $GL_1(\RR)$ will work as well — associated to $L$ is then a locally trivial fibre bundle $p:E\to X$. The principal bundle $p:E\to X$ does not admit a section, since the line bundle $L$ is not trivial. It follows that $p$ cannot be a Hurewicz fibration: otherwise it would admit a section, given that $X$ is contractible. For convenience, I will give below the construction of $p:E\to X$ and a few details of the proof — mostly copied from Tom's answer, and following his notation where possible. Please upvote Tom Goodwillie's answer, which is certainly shorter and more readable.
### The base space $X$
Let $X$ be the space obtained by gluing two copies of $\RR$ along $\RR^+$: $$X = (\RR\times\{0,1\})\mathbin{/}{\sim}$$ where ${\sim}$ is generated by $(x,0)\sim(x,1)$ for $x\in\RR^+$. This space is not Hausdorff, and is closely related to the well-known line with two origins. Let $q:\RR\times\{0,1\}\to X$ be the quotient map. Define two open subspaces covering $X$ by $U=q(\RR\times\{0\})$ and $V=q(\RR\times\{1\})$. Finally, let $g:X\to\RR$ be the continuous function determined by $g(q(x,i))=x$, and define $$f=g|_{U\cap V}: U\cap V \To \RR^+$$ Importantly, observe that $f$ does not extend to a continuous map $X\to\RR^+$.
### The total space $E$
Consider the topological abelian group $G=GL_1^+(\RR)=(\RR^+,\cdot)$ given by the positive reals with multiplication. Let $E_U=U\times G$ and $E_V= V\times G$ denote the trivial $G$-bundles over $U$ and $V$, respectively. Construct the principal $G$-bundle $E$ over $X$ by gluing $E_U$ and $E_V$ along $U\cap V$ via the $G$-isomorphism $$\varphi_f : E_U|_{U\cap V}\overset{\simeq}{\To} E_V|_{U\cap V}$$ defined by $$\varphi_f(x,g)=\bigl(x,f(x)\cdot g\bigr)$$ More concretely, $E$ is obtained from $E_U \amalg E_V$ by identifying $(x,g)\in E_U$ with $\varphi_f(x,g)\in E_V$ for each $x\in U\cap V$. As in Tom Goodwillie's answer, we could just as well use any other continuous function $f:U\cap V\to\RR^+$ which does not extend to a continuous function $X\to\RR^+$.
### Non-triviality of the principal bundle $E\to X$
The projection map $p:E\to X$ gives a principal $G$-bundle over $X$, which comes with canonical isomorphisms $E|_U = E_U$ and $E|_V = E_V$. We will now show $p$ does not admit a section. By the construction of $E$, a section of $p:E\to X$ determines:
• a section of $E_U=U\times G\to U$, and therefore a map $s_U:U\to G=\RR^+$;
• similarly, a map $s_V:V\to G=\RR^+$;
• these maps verify $s_V(x)=f(x)\cdot s_U(x)$ for each $x\in U\cap V$.
In particular, $f(x)=s_V(x)/s_U(x)$ for all $x\in U\cap V$. However, this implies that $f$ extends to a continuous function $\overline{f}:X\to\RR^+$ given by $$\overline{f}(x)=\frac{s_V\bigl(q(g(x),1)\bigr)}{s_U\bigl(q(g(x),0)\bigr)}$$ which contradicts the known non-extension property of $f$.
### Conclusion
The projection $p:E\to X$ gives a locally trivial principal $G$-bundle over $X$, since $E|_U\simeq E_U$ and $E|_V\simeq E_V$ are trivial $G$-bundles. Thus, it remains to show that $p$ is not a Hurewicz fibration. Note that $X$ is contractible. So if $p:E\to X$ were a fibration, it would necessarily admit a section. In detail, let $H:X\times I\to X$ be a null-homotopy of $\id_X$. We can obviously lift the constant map $H_1$ to $E$. Assuming $p$ is a Hurewicz fibration, the homotopy lifting property then produces a lift $\widetilde{H}: X\times I\to E$ of $H$ to $E$, and consequently a section $\widetilde{H}_0$ of $p$. But we showed in the previous paragraph that $p$ admits no sections. In conclusion, $p$ is not a Hurewicz fibration.
• " Specifically, Tom defines an orientable, non-trivial, real line bundle L over a contractible space X" -- I thought fibre bundles over contractible spaces are always trivial? Is there some necessary restriction on the base for this to hold? – ಠ_ಠ Sep 29 '16 at 1:17
• @ಠ_ಠ if the bundle had a classifying map, then necessarily it would be trivial, because the classifying map would be null-homotopic. But due to the fact the bundle doesn't trivialise over a numerable cover (as the line with two origins is not Hausdorff paracompact) there is no classifying map. – David Roberts Jul 19 '17 at 6:33
|
{"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": 1, "mathjax_asciimath": 0, "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": 0.9790197610855103, "perplexity": 162.73870033411217}, "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-2021-10/segments/1614178375529.62/warc/CC-MAIN-20210306223236-20210307013236-00501.warc.gz"}
|
https://brilliant.org/problems/irrational-equation/
|
# Irrational equation
Algebra Level 3
What is the sum of the real solutions for the following equation: $\sqrt{x^2+x+5}=2+\sqrt{x^2+x-11}?$
×
|
{"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": 0, "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": 0.9520500898361206, "perplexity": 1480.356787963555}, "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-2019-04/segments/1547583728901.52/warc/CC-MAIN-20190120163942-20190120185942-00438.warc.gz"}
|
https://www.biostars.org/p/262862/
|
x-axis is not displaying all my scaffolds in qqman r package
0
0
Entering edit mode
3.7 years ago
ggman ▴ 80
Hello friends,
I am using qqman (an R package) to create a manhattan plot from a data set based on statistics. So it is working well but it is omitting 2/3 of my data for whatever reason... I am using this guide to try and solve the issue but I am not sure how to address it. I have 700 scaffolds and it is only showing about 250 scaffolds. When I change the dimensions, it makes the plot cleaner but the x-axis is still omitting my data. I am thinking that if I make the spacing even between the points on the x-axis it would help but it doesn't account for my missing data.
Below is my code from R-studio and the qqman R-package
manhattan(qq.data, chr="chrom", bp = "start", p = "fst", snp = "snp",logp=FALSE,ylab="fst")
Any guidance is appreciated friends!
qqman manhattan plot R package snps R • 1.7k views
|
{"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": 0.1674017310142517, "perplexity": 2005.9916306099046}, "config": {"markdown_headings": false, "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-2021-17/segments/1618038075074.29/warc/CC-MAIN-20210413213655-20210414003655-00465.warc.gz"}
|
https://planetcalc.com/497/
|
homechevron_rightStudychevron_rightMath
# The greatest common divisor and the least common multiple of two integers
This calculator finds the greatest common divisor (GCD) and the least common multiple (LCM) of two integers
The greatest common divisor (GCD) can be found using Euclidean algorithm. See description here - The greatest common divisor of two integers.
If you knew GCD, you can find the least common multiple (LCM) easily
$[a,b]=\frac{ab}{(a,b)}$,
where
[a,b] - LCM,
(a,b) - GCD.
#### The greatest common divisor and the lowest common multiple of two integers
The lowest common multiple
The greatest common divisor
PLANETCALC, The greatest common divisor and the least common multiple of two integers
|
{"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": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 1, "/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": 0.7794962525367737, "perplexity": 229.00627714815056}, "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-2020-29/segments/1593655882934.6/warc/CC-MAIN-20200703184459-20200703214459-00180.warc.gz"}
|
https://dsp.stackexchange.com/questions/26395/signal-reconstruction-error-in-compressed-sensing
|
# signal reconstruction error in compressed sensing
Does the signal reconstruction error in compressed sensing using $l_1$ norm minimization depends on the amplitude of non-zero coefficients and their location ?
• No,but the number of non zero coefficients has effect on the quality – Abhishek Sadasivan Feb 4 '16 at 19:29
Yes and No. If you consider your signal, noise free, meaning that all of the zero elements are really zero, then your answer is No, however though if the input noise is taken into the account, then the higher amplitude of the non-zero elements results in better signal reconstruction (high input SNR gives high output SNR).
Typically in Compressive Sensing, the reconstruction error is defined in terms of mean squared error (MSE):
$$MSE = \frac{|| \hat{x} - x ||_2^2}{||x||_2^2}$$
where $$|| y ||_2^2 = \sum_{i=0}^{n-1} y_i^2$$
For a sparse signal this will simply be
$$||y_{sparse}||_2^2 = \sum_{j \in S_{sparse}} y_i^2$$
where $S_{sparse}$ is the set of non-zero coefficients in the vector $y$. Note that this is independent of the indices $j$ - a permutation will give the same MSE.
• Thanks for your kind reply. I think this one is only for location. What about the amplitude of non-zero elements? – J Cian Mar 5 '16 at 17:32
• No, this is for multiple locations. – Tom Kealy Mar 5 '16 at 19:38
|
{"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": 1, "mathjax_asciimath": 0, "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": 0.9303483963012695, "perplexity": 454.46111354023225}, "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/1610704798089.76/warc/CC-MAIN-20210126042704-20210126072704-00554.warc.gz"}
|
http://worldwidescience.org/topicpages/c/cat+primary+auditory.html
|
#### Sample records for cat primary auditory
1. Cross-correlations between three units in cat primary auditory cortex.
Eggermont, Jos J; Munguia, Raymundo; Shaw, Gregory
2013-10-01
Here we use a modification of the Joint-Peri-Stimulus-Time histogram (JPSTH) to investigate triple correlations between cat auditory cortex neurons. The modified procedure allowed the decomposition of the xy-pair correlation into a part that is due to the correlation of the x and y units with the trigger unit, and a remaining 'pair correlation'. We analyzed 16 sets of 15-minute duration stationary spontaneous recordings in primary auditory cortex (AI) with between 11 and 14 electrodes from 2 arrays of 8 electrodes each that provided spontaneous firing rates above 0.22 sp/s and for which reliable frequency-tuning curves could be obtained and the characteristic frequency (CF) was estimated. Thus we evaluated 11,282 conditional cross-correlation functions. The predictor for the conditional cross-correlation, calculated on the assumption that the trigger unit had no effect on the xy-pair correlation but using the same fraction of xy spikes, was equal to the conventional pair-wise correlation function between units xy. The conditional correlation of the xy-pair due to correlation of the x and/or y unit with the trigger unit decreased with the geometric mean distance of the xy pair to the trigger unit, but was independent of the pair cross-correlation coefficient. The conditional pair correlation coefficient was estimated at 78% of the measured pair correlation coefficient. Assuming a geometric decreasing effect of activities of units on other electrodes on the conditional correlation, we estimated the potential contribution of a large number of contributing units on the measured pair correlation at 35-50 of that correlation. This suggests that conventionally measured pair correlations in auditory cortex under ketamine anesthesia overestimate the 'true pair correlation', likely resulting from massive common input, by potentially up to a factor 2. PMID:23933479
2. Spectrotemporal receptive fields during spindling and non-spindling epochs in cat primary auditory cortex.
Britvina, T; Eggermont, J J
2008-07-17
It was often thought that synchronized rhythmic epochs of spindle waves disconnect thalamo-cortical system from incoming sensory signals. The present study addresses this issue by simultaneous extracellular action potential and local field potential (LFP) recordings from primary auditory cortex of ketamine-anesthetized cats during spindling activity. We compared cortical spectrotemporal receptive fields (STRF) obtained during spindling and non-spindling epochs. The basic spectro-temporal parameters of "spindling" and "non-spindling" STRFs were similar. However, the peak-firing rate at the best frequency was significantly enhanced during spindling epochs. This enhancement was mainly caused by the increased probability of a stimulus to evoke spikes (effectiveness of stimuli) during spindling as compared with non-spindling epochs. Augmented LFPs associated with effective stimuli and increased single-unit pair correlations during spindling epochs suggested higher synchrony of thalamo-cortical inputs during spindling that resulted in increased effectiveness of stimuli presented during spindling activity. The neuronal firing rate, both stimulus-driven and spontaneous, was higher during spindling as compared with non-spindling epochs. Overall, our results suggests that thalamic cells during spindling respond to incoming stimuli-related inputs and, moreover, cause more powerful stimulus-related or spontaneous activation of the cortex. PMID:18515012
3. Comparison of LFP-Based and Spike-Based Spectro-Temporal Receptive Fields and Cross-Correlation in Cat Primary Auditory Cortex
Eggermont, Jos J.; Munguia, Raymundo; Pienkowski, Martin; Shaw, Greg
2011-01-01
Multi-electrode array recordings of spike and local field potential (LFP) activity were made from primary auditory cortex of 12 normal hearing, ketamine-anesthetized cats. We evaluated 259 spectro-temporal receptive fields (STRFs) and 492 frequency-tuning curves (FTCs) based on LFPs and spikes simultaneously recorded on the same electrode. We compared their characteristic frequency (CF) gradients and their cross-correlation distances. The CF gradient for spike-based FTCs was about twice that ...
4. Neural Correlates of an Auditory Afterimage in Primary Auditory Cortex
Noreña, A. J.; Eggermont, J. J.
2003-01-01
The Zwicker tone (ZT) is defined as an auditory negative afterimage, perceived after the presentation of an appropriate inducer. Typically, a notched noise (NN) with a notch width of 1/2 octave induces a ZT with a pitch falling in the frequency range of the notch. The aim of the present study was to find potential neural correlates of the ZT in the primary auditory cortex of ketamine-anesthetized cats. Responses of multiunits were recorded simultaneously with two 8-electrode arrays during 1 s...
5. Comparison of LFP-based and spike-based spectro-temporal receptive fields and cross-correlation in cat primary auditory cortex.
Jos J Eggermont
Full Text Available Multi-electrode array recordings of spike and local field potential (LFP activity were made from primary auditory cortex of 12 normal hearing, ketamine-anesthetized cats. We evaluated 259 spectro-temporal receptive fields (STRFs and 492 frequency-tuning curves (FTCs based on LFPs and spikes simultaneously recorded on the same electrode. We compared their characteristic frequency (CF gradients and their cross-correlation distances. The CF gradient for spike-based FTCs was about twice that for 2-40 Hz-filtered LFP-based FTCs, indicating greatly reduced frequency selectivity for LFPs. We also present comparisons for LFPs band-pass filtered between 4-8 Hz, 8-16 Hz and 16-40 Hz, with spike-based STRFs, on the basis of their marginal frequency distributions. We find on average a significantly larger correlation between the spike based marginal frequency distributions and those based on the 16-40 Hz filtered LFP, compared to those based on the 4-8 Hz, 8-16 Hz and 2-40 Hz filtered LFP. This suggests greater frequency specificity for the 16-40 Hz LFPs compared to those of lower frequency content. For spontaneous LFP and spike activity we evaluated 1373 pair correlations for pairs with >200 spikes in 900 s per electrode. Peak correlation-coefficient space constants were similar for the 2-40 Hz filtered LFP (5.5 mm and the 16-40 Hz LFP (7.4 mm, whereas for spike-pair correlations it was about half that, at 3.2 mm. Comparing spike-pairs with 2-40 Hz (and 16-40 Hz LFP-pair correlations showed that about 16% (9% of the variance in the spike-pair correlations could be explained from LFP-pair correlations recorded on the same electrodes within the same electrode array. This larger correlation distance combined with the reduced CF gradient and much broader frequency selectivity suggests that LFPs are not a substitute for spike activity in primary auditory cortex.
6. Comparison of LFP-based and spike-based spectro-temporal receptive fields and cross-correlation in cat primary auditory cortex.
Eggermont, Jos J; Munguia, Raymundo; Pienkowski, Martin; Shaw, Greg
2011-01-01
Multi-electrode array recordings of spike and local field potential (LFP) activity were made from primary auditory cortex of 12 normal hearing, ketamine-anesthetized cats. We evaluated 259 spectro-temporal receptive fields (STRFs) and 492 frequency-tuning curves (FTCs) based on LFPs and spikes simultaneously recorded on the same electrode. We compared their characteristic frequency (CF) gradients and their cross-correlation distances. The CF gradient for spike-based FTCs was about twice that for 2-40 Hz-filtered LFP-based FTCs, indicating greatly reduced frequency selectivity for LFPs. We also present comparisons for LFPs band-pass filtered between 4-8 Hz, 8-16 Hz and 16-40 Hz, with spike-based STRFs, on the basis of their marginal frequency distributions. We find on average a significantly larger correlation between the spike based marginal frequency distributions and those based on the 16-40 Hz filtered LFP, compared to those based on the 4-8 Hz, 8-16 Hz and 2-40 Hz filtered LFP. This suggests greater frequency specificity for the 16-40 Hz LFPs compared to those of lower frequency content. For spontaneous LFP and spike activity we evaluated 1373 pair correlations for pairs with >200 spikes in 900 s per electrode. Peak correlation-coefficient space constants were similar for the 2-40 Hz filtered LFP (5.5 mm) and the 16-40 Hz LFP (7.4 mm), whereas for spike-pair correlations it was about half that, at 3.2 mm. Comparing spike-pairs with 2-40 Hz (and 16-40 Hz) LFP-pair correlations showed that about 16% (9%) of the variance in the spike-pair correlations could be explained from LFP-pair correlations recorded on the same electrodes within the same electrode array. This larger correlation distance combined with the reduced CF gradient and much broader frequency selectivity suggests that LFPs are not a substitute for spike activity in primary auditory cortex. PMID:21625385
7. Primary hypoadrenocorticism in ten cats.
Peterson, M E; Greco, D S; Orth, D N
1989-01-01
Primary hypoadrenocorticism was diagnosed in ten young to middle-aged cats of mixed breeding. Five of the cats were male, and five were female. Historic signs included lethargy (n = 10), anorexia (n = 10), weight loss (n = 9), vomiting (n = 4), and polyuria (n = 3). Dehydration (n = 9), hypothermia (n = 8), prolonged capillary refill time (n = 5), weak pulse (n = 5), collapse (n = 3), and sinus bradycardia (n = 2) were found on physical examination. Results of initial laboratory tests revealed anemia (n = 3), absolute lymphocytosis (n = 2), absolute eosinophilia (n = 1), and azotemia and hyperphosphatemia (n = 10). Serum electrolyte changes included hyponatremia (n = 10), hyperkalemia (n = 9), hypochloremia (n = 9), and hypercalcemia (n = 1). The diagnosis of primary adrenocortical insufficiency was established on the basis of results of adrenocorticotropic hormone (ACTH) stimulation tests (n = 10) and endogenous plasma ACTH determinations (n = 7). Initial therapy for hypoadrenocorticism included intravenous administration of 0.9% saline and dexamethasone and intramuscular administration of desoxycorticosterone acetate in oil. Three cats were euthanatized shortly after diagnosis because of poor clinical response. Results of necropsy examination were unremarkable except for complete destruction of both adrenal cortices. Seven cats were treated chronically with oral prednisone or intramuscular methylprednisolone acetate for glucocorticoid supplementation and with oral fludrocortisone acetate or intramuscular injections of repository desoxycorticosterone pivalate for mineralocorticoid replacement. One cat died after 47 days of therapy from unknown causes; the other six cats are still alive and well after 3 to 70 months of treatment. PMID:2469793
8. Characterization of the blood-oxygen level-dependent (BOLD) response in cat auditory cortex using high-field fMRI.
Brown, Trecia A; Joanisse, Marc F; Gati, Joseph S; Hughes, Sarah M; Nixon, Pam L; Menon, Ravi S; Lomber, Stephen G
2013-01-01
Much of what is known about the cortical organization for audition in humans draws from studies of auditory cortex in the cat. However, these data build largely on electrophysiological recordings that are both highly invasive and provide less evidence concerning macroscopic patterns of brain activation. Optical imaging, using intrinsic signals or dyes, allows visualization of surface-based activity but is also quite invasive. Functional magnetic resonance imaging (fMRI) overcomes these limitations by providing a large-scale perspective of distributed activity across the brain in a non-invasive manner. The present study used fMRI to characterize stimulus-evoked activity in auditory cortex of an anesthetized (ketamine/isoflurane) cat, focusing specifically on the blood-oxygen-level-dependent (BOLD) signal time course. Functional images were acquired for adult cats in a 7 T MRI scanner. To determine the BOLD signal time course, we presented 1s broadband noise bursts between widely spaced scan acquisitions at randomized delays (1-12 s in 1s increments) prior to each scan. Baseline trials in which no stimulus was presented were also acquired. Our results indicate that the BOLD response peaks at about 3.5s in primary auditory cortex (AI) and at about 4.5 s in non-primary areas (AII, PAF) of cat auditory cortex. The observed peak latency is within the range reported for humans and non-human primates (3-4 s). The time course of hemodynamic activity in cat auditory cortex also occurs on a comparatively shorter scale than in cat visual cortex. The results of this study will provide a foundation for future auditory fMRI studies in the cat to incorporate these hemodynamic response properties into appropriate analyses of cat auditory cortex. PMID:23000258
9. The cat's meow: A high-field fMRI assessment of cortical activity in response to vocalizations and complex auditory stimuli.
Hall, Amee J; Butler, Blake E; Lomber, Stephen G
2016-02-15
Sensory systems are typically constructed in a hierarchical fashion such that lower level subcortical and cortical areas process basic stimulus features, while higher level areas reassemble these features into object-level representations. A number of anatomical pathway tracing studies have suggested that the auditory cortical hierarchy of the cat extends from a core region, consisting of the primary auditory cortex (A1) and the anterior auditory field (AAF), to higher level auditory fields that are located ventrally. Unfortunately, limitations on electrophysiological examination of these higher level fields have resulted in an incomplete understanding of the functional organization of the auditory cortex. Thus, the current study uses functional MRI in conjunction with a variety of simple and complex auditory stimuli to provide the first comprehensive examination of function across the entire cortical hierarchy. Auditory cortex function is shown to be largely lateralized to the left hemisphere, and is concentrated bilaterally in fields surrounding the posterior ectosylvian sulcus. The use of narrowband noise stimuli enables the visualization of tonotopic gradients in the posterior auditory field (PAF) and ventral posterior auditory field (VPAF) that have previously been unverifiable using fMRI and pure tones. Furthermore, auditory fields that are inaccessible to more invasive techniques, such as the insular (IN) and temporal (T) cortices, are shown to be selectively responsive to vocalizations. Collectively, these data provide a much needed functional correlate for anatomical examinations of the hierarchy of cortical structures within the cat auditory cortex. PMID:26658927
10. Primary pulmonary neoplasia in the dog and cat
This article covers the pertinent clinical, physical, and radiographic findings in dogs and cats with primary pulmonary neoplasia. Diagnostic and treatment recommendations are made. Although primary pulmonary neoplasia is rare in both the dog and cat, it appears to be diagnosed with increasing frequency. Early detection and surgical treatment of carefully selected cases can prolong a good quality of life
11. Functional sex differences in human primary auditory cortex
Ruytjens, Liesbet; Georgiadis, Janniko R.; Holstege, Gert; Wit, Hero P.; Albers, Frans W. J.; Willemsen, Antoon T. M.
2007-01-01
Background We used PET to study cortical activation during auditory stimulation and found sex differences in the human primary auditory cortex (PAC). Regional cerebral blood flow (rCBF) was measured in 10 male and 10 female volunteers while listening to sounds (music or white noise) and during a bas
12. Improvement of auditory hallucinations and reduction of primary auditory area's activation following TMS
Background: In the present case study, improvement of auditory hallucinations following transcranial magnetic stimulation (TMS) therapy was investigated with respect to activation changes of the auditory cortices. Methods: Using functional magnetic resonance imaging (fMRI), activation of the auditory cortices was assessed prior to and after a 4-week TMS series of the left superior temporal gyrus in a schizophrenic patient with medication-resistant auditory hallucinations. Results: Hallucinations decreased slightly after the third and profoundly after the fourth week of TMS. Activation in the primary auditory area decreased, whereas activation in the operculum and insula remained stable. Conclusions: Combination of TMS and repetitive fMRI is promising to elucidate the physiological changes induced by TMS.
13. Neurogenesis in the brain auditory pathway of a marsupial, the northern native cat (Dasyurus hallucatus)
Neurogenesis in the auditory pathway of the marsupial Dasyurus hallucatus was studied. Intraperitoneal injections of tritiated thymidine (20-40 microCi) were made into pouch-young varying from 1 to 56 days pouch-life. Animals were killed as adults and brain sections were prepared for autoradiography and counterstained with a Nissl stain. Neurons in the ventral cochlear nucleus were generated prior to 3 days pouch-life, in the superior olive at 5-7 days, and in the dorsal cochlear nucleus over a prolonged period. Inferior collicular neurogenesis lagged behind that in the medial geniculate, the latter taking place between days 3 and 9 and the former between days 7 and 22. Neurogenesis began in the auditory cortex on day 9 and was completed by about day 42. Thus neurogenesis was complete in the medullary auditory nuclei before that in the midbrain commenced, and in the medial geniculate before that in the auditory cortex commenced. The time course of neurogenesis in the auditory pathway of the native cat was very similar to that in another marsupial, the brushtail possum. For both, neurogenesis occurred earlier than in eutherian mammals of a similar size but was more protracted
14. Neurogenesis in the brain auditory pathway of a marsupial, the northern native cat (Dasyurus hallucatus)
Aitkin, L.; Nelson, J.; Farrington, M.; Swann, S. (Department of Physiology, Monash University, Melbourne (Australia))
1991-07-08
Neurogenesis in the auditory pathway of the marsupial Dasyurus hallucatus was studied. Intraperitoneal injections of tritiated thymidine (20-40 microCi) were made into pouch-young varying from 1 to 56 days pouch-life. Animals were killed as adults and brain sections were prepared for autoradiography and counterstained with a Nissl stain. Neurons in the ventral cochlear nucleus were generated prior to 3 days pouch-life, in the superior olive at 5-7 days, and in the dorsal cochlear nucleus over a prolonged period. Inferior collicular neurogenesis lagged behind that in the medial geniculate, the latter taking place between days 3 and 9 and the former between days 7 and 22. Neurogenesis began in the auditory cortex on day 9 and was completed by about day 42. Thus neurogenesis was complete in the medullary auditory nuclei before that in the midbrain commenced, and in the medial geniculate before that in the auditory cortex commenced. The time course of neurogenesis in the auditory pathway of the native cat was very similar to that in another marsupial, the brushtail possum. For both, neurogenesis occurred earlier than in eutherian mammals of a similar size but was more protracted.
15. Functional sex differences in human primary auditory cortex
We used PET to study cortical activation during auditory stimulation and found sex differences in the human primary auditory cortex (PAC). Regional cerebral blood flow (rCBF) was measured in 10 male and 10 female volunteers while listening to sounds (music or white noise) and during a baseline (no auditory stimulation). We found a sex difference in activation of the left and right PAC when comparing music to noise. The PAC was more activated by music than by noise in both men and women. But this difference between the two stimuli was significantly higher in men than in women. To investigate whether this difference could be attributed to either music or noise, we compared both stimuli with the baseline and revealed that noise gave a significantly higher activation in the female PAC than in the male PAC. Moreover, the male group showed a deactivation in the right prefrontal cortex when comparing noise to the baseline, which was not present in the female group. Interestingly, the auditory and prefrontal regions are anatomically and functionally linked and the prefrontal cortex is known to be engaged in auditory tasks that involve sustained or selective auditory attention. Thus we hypothesize that differences in attention result in a different deactivation of the right prefrontal cortex, which in turn modulates the activation of the PAC and thus explains the sex differences found in the activation of the PAC. Our results suggest that sex is an important factor in auditory brain studies. (orig.)
16. Functional sex differences in human primary auditory cortex
Ruytjens, Liesbet [University Medical Center Groningen, Department of Otorhinolaryngology, Groningen (Netherlands); University Medical Center Utrecht, Department Otorhinolaryngology, P.O. Box 85500, Utrecht (Netherlands); Georgiadis, Janniko R. [University of Groningen, University Medical Center Groningen, Department of Anatomy and Embryology, Groningen (Netherlands); Holstege, Gert [University of Groningen, University Medical Center Groningen, Center for Uroneurology, Groningen (Netherlands); Wit, Hero P. [University Medical Center Groningen, Department of Otorhinolaryngology, Groningen (Netherlands); Albers, Frans W.J. [University Medical Center Utrecht, Department Otorhinolaryngology, P.O. Box 85500, Utrecht (Netherlands); Willemsen, Antoon T.M. [University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Groningen (Netherlands)
2007-12-15
We used PET to study cortical activation during auditory stimulation and found sex differences in the human primary auditory cortex (PAC). Regional cerebral blood flow (rCBF) was measured in 10 male and 10 female volunteers while listening to sounds (music or white noise) and during a baseline (no auditory stimulation). We found a sex difference in activation of the left and right PAC when comparing music to noise. The PAC was more activated by music than by noise in both men and women. But this difference between the two stimuli was significantly higher in men than in women. To investigate whether this difference could be attributed to either music or noise, we compared both stimuli with the baseline and revealed that noise gave a significantly higher activation in the female PAC than in the male PAC. Moreover, the male group showed a deactivation in the right prefrontal cortex when comparing noise to the baseline, which was not present in the female group. Interestingly, the auditory and prefrontal regions are anatomically and functionally linked and the prefrontal cortex is known to be engaged in auditory tasks that involve sustained or selective auditory attention. Thus we hypothesize that differences in attention result in a different deactivation of the right prefrontal cortex, which in turn modulates the activation of the PAC and thus explains the sex differences found in the activation of the PAC. Our results suggest that sex is an important factor in auditory brain studies. (orig.)
17. Quantifying and comparing the pattern of thalamic and cortical projections to the posterior auditory field in hearing and deaf cats.
Butler, Blake E; Chabot, Nicole; Lomber, Stephen G
2016-10-15
Following sensory loss, compensatory crossmodal reorganization occurs such that the remaining modalities are functionally enhanced. For example, behavioral evidence suggests that peripheral visual localization is better in deaf than in normal hearing animals, and that this enhancement is mediated by recruitment of the posterior auditory field (PAF), an area that is typically involved in localization of sounds in normal hearing animals. To characterize the anatomical changes that underlie this phenomenon, we identified the thalamic and cortical projections to the PAF in hearing cats and those with early- and late-onset deafness. The retrograde tracer biotinylated dextran amine was deposited in the PAF unilaterally, to label cortical and thalamic afferents. Following early deafness, there was a significant decrease in callosal projections from the contralateral PAF. Late-deaf animals showed small-scale changes in projections from one visual cortical area, the posterior ectosylvian field (EPp), and the multisensory zone (MZ). With the exception of these minor differences, connectivity to the PAF was largely similar between groups, with the principle projections arising from the primary auditory cortex (A1) and the ventral division of the medial geniculate body (MGBv). This absence of large-scale connectional change suggests that the functional reorganization that follows sensory loss results from changes in synaptic strength and/or unmasking of subthreshold intermodal connections. J. Comp. Neurol. 524:3042-3063, 2016. © 2016 Wiley Periodicals, Inc. PMID:27019080
18. Encoding of temporal information by timing, rate, and place in cat auditory cortex.
Kazuo Imaizumi
Full Text Available A central goal in auditory neuroscience is to understand the neural coding of species-specific communication and human speech sounds. Low-rate repetitive sounds are elemental features of communication sounds, and core auditory cortical regions have been implicated in processing these information-bearing elements. Repetitive sounds could be encoded by at least three neural response properties: 1 the event-locked spike-timing precision, 2 the mean firing rate, and 3 the interspike interval (ISI. To determine how well these response aspects capture information about the repetition rate stimulus, we measured local group responses of cortical neurons in cat anterior auditory field (AAF to click trains and calculated their mutual information based on these different codes. ISIs of the multiunit responses carried substantially higher information about low repetition rates than either spike-timing precision or firing rate. Combining firing rate and ISI codes was synergistic and captured modestly more repetition information. Spatial distribution analyses showed distinct local clustering properties for each encoding scheme for repetition information indicative of a place code. Diversity in local processing emphasis and distribution of different repetition rate codes across AAF may give rise to concurrent feed-forward processing streams that contribute differently to higher-order sound analysis.
19. Primary hyperaldosteronism, a mediator of progressive renal disease in cats.
Javadi, S; Djajadiningrat-Laanen, S C; Kooistra, H S; van Dongen, A M; Voorhout, G; van Sluijs, F J; van den Ingh, T S G A M; Boer, W H; Rijnberk, A
2005-01-01
In recent years, there has been renewed interest in primary hyperaldosteronism, particularly because of its possible role in the progression of kidney disease. While most studies have concerned humans and experimental animal models, we here report on the occurrence of a spontaneous form of (non-tumorous) primary hyperaldosteronism in cats. At presentation, the main physical features of 11 elderly cats were hypokalemic paroxysmal flaccid paresis and loss of vision due to retinal detachment with hemorrhages. Primary hyperaldosteronism was diagnosed on the basis of plasma concentrations of aldosterone (PAC) and plasma renin activity (PRA), and the calculation of the PAC:PRA ratio. In all animals, PACs were at the upper end or higher than the reference range. The PRAs were at the lower end of the reference range, and the PAC:PRA ratios exceeded the reference range. Diagnostic imaging by ultrasonography and computed tomography revealed no or only very minor changes in the adrenals compatible with nodular hyperplasia. Adrenal gland histopathology revealed extensive micronodular hyperplasia extending from zona glomerulosa into the zona fasciculata and reticularis. In three cats, plasma urea and creatinine concentrations were normal when hyperaldosteronism was diagnosed but thereafter increased to above the upper limit of the respective reference range. In the other eight cats, urea and creatinine concentrations were raised at first examination and gradually further increased. Even in end-stage renal insufficiency, there was a tendency to hypophosphatemia rather than to hyperphosphatemia. The histopathological changes in the kidneys mimicked those of humans with hyperaldosteronism: hyaline arteriolar sclerosis, glomerular sclerosis, tubular atrophy and interstitial fibrosis. The non-tumorous form of primary hyperaldosteronism in cats has many similarities with "idiopathic" primary hyperaldosteronism in humans. The condition is associated with progressive renal disease
20. Core auditory processing deficits in primary progressive aphasia
Grube, Manon; Bruffaerts, Rose; Schaeverbeke, Jolien; Neyens, Veerle; De Weer, An-Sofie; Seghers, Alexandra; Bergmans, Bruno; Dries, Eva; Griffiths, Timothy D.
2016-01-01
The extent to which non-linguistic auditory processing deficits may contribute to the phenomenology of primary progressive aphasia is not established. Using non-linguistic stimuli devoid of meaning we assessed three key domains of auditory processing (pitch, timing and timbre) in a consecutive series of 18 patients with primary progressive aphasia (eight with semantic variant, six with non-fluent/agrammatic variant, and four with logopenic variant), as well as 28 age-matched healthy controls. We further examined whether performance on the psychoacoustic tasks in the three domains related to the patients’ speech and language and neuropsychological profile. At the group level, patients were significantly impaired in the three domains. Patients had the most marked deficits within the rhythm domain for the processing of short sequences of up to seven tones. Patients with the non-fluent variant showed the most pronounced deficits at the group and the individual level. A subset of patients with the semantic variant were also impaired, though less severely. The patients with the logopenic variant did not show any significant impairments. Significant deficits in the non-fluent and the semantic variant remained after partialling out effects of executive dysfunction. Performance on a subset of the psychoacoustic tests correlated with conventional verbal repetition tests. In sum, a core central auditory impairment exists in primary progressive aphasia for non-linguistic stimuli. While the non-fluent variant is clinically characterized by a motor speech deficit (output problem), perceptual processing of tone sequences is clearly deficient. This may indicate the co-occurrence in the non-fluent variant of a deficit in working memory for auditory objects. Parsimoniously we propose that auditory timing pathways are altered, which are used in common for processing acoustic sequence structure in both speech output and acoustic input. PMID:27060523
1. Core auditory processing deficits in primary progressive aphasia.
Grube, Manon; Bruffaerts, Rose; Schaeverbeke, Jolien; Neyens, Veerle; De Weer, An-Sofie; Seghers, Alexandra; Bergmans, Bruno; Dries, Eva; Griffiths, Timothy D; Vandenberghe, Rik
2016-06-01
The extent to which non-linguistic auditory processing deficits may contribute to the phenomenology of primary progressive aphasia is not established. Using non-linguistic stimuli devoid of meaning we assessed three key domains of auditory processing (pitch, timing and timbre) in a consecutive series of 18 patients with primary progressive aphasia (eight with semantic variant, six with non-fluent/agrammatic variant, and four with logopenic variant), as well as 28 age-matched healthy controls. We further examined whether performance on the psychoacoustic tasks in the three domains related to the patients' speech and language and neuropsychological profile. At the group level, patients were significantly impaired in the three domains. Patients had the most marked deficits within the rhythm domain for the processing of short sequences of up to seven tones. Patients with the non-fluent variant showed the most pronounced deficits at the group and the individual level. A subset of patients with the semantic variant were also impaired, though less severely. The patients with the logopenic variant did not show any significant impairments. Significant deficits in the non-fluent and the semantic variant remained after partialling out effects of executive dysfunction. Performance on a subset of the psychoacoustic tests correlated with conventional verbal repetition tests. In sum, a core central auditory impairment exists in primary progressive aphasia for non-linguistic stimuli. While the non-fluent variant is clinically characterized by a motor speech deficit (output problem), perceptual processing of tone sequences is clearly deficient. This may indicate the co-occurrence in the non-fluent variant of a deficit in working memory for auditory objects. Parsimoniously we propose that auditory timing pathways are altered, which are used in common for processing acoustic sequence structure in both speech output and acoustic input. PMID:27060523
2. [Depolarization of primary afferents during real scratching in the cat].
Baev, K V; Esipenko, V B
1985-01-01
Changes in depolarization of primary afferents and their correlation with afferent impulsation and limb movement were studied in the lumbar spinal cord during real scratching of decerebrated cats. Two components in rhythmic dorsal root potential were observed. First--centrally evoked, retained during fictitive scratching after immobilization; second--evoked by afferent discharge, coming to the spinal cord during the scratching phase of the limb movement. PMID:3974754
3. Primary immune-mediated neutropenia in a cat
Waugh, Carly E.; Scott, Katherine D.; Bryan, Laura K.
2014-01-01
An 18-month-old male castrated indoor Himalayan cat was presented for recurrent fever, lethargy, and uveitis. Persistent neutropenia was identified and tests for infectious disease and bone marrow cytology were performed. Primary immune-mediated neutropenia was diagnosed and successfully treated. At the time of writing this report, 24 mo after the initial diagnosis. the patient was clinically normal and not receiving therapy.
4. 9 CFR 3.14 - Primary enclosures used to transport live dogs and cats.
2010-01-01
... transport live dogs and cats. Any person subject to the Animal Welfare regulations (9 CFR parts 1, 2, and 3) must not transport or deliver for transport in commerce a dog or cat unless the following requirements are met: (a) Construction of primary enclosures. The dog or cat must be contained in a...
5. Inherited primary hypothyroidism with thyrotrophin resistance in Japanese cats.
Tanase, H; Kudo, K; Horikoshi, H; Mizushima, H; Okazaki, T; Ogata, E
1991-05-01
Mutant cats were developed with non-goitrous primary hypothyroidism. They were clinically characterized by severely retarded growth, mild anaemia and high mortality in the young. They responded markedly to thyroid hormone replacement. Thyroid glands in the mutants were normal in position but slightly reduced in size. Laboratory studies revealed low serum concentrations of thyroxine (T4) and tri-iodothyronine (T3), and increased serum concentrations of TSH. Administration of TRH induced no further increase in TSH. Administration of exogenous TSH after suppression of endogenous TSH by T3 did not increase the serum concentration of T4 in the mutants, in sharp contrast with the threefold increase in serum T4 observed in the normal litter-mates. These findings suggest that the underlying pathogenesis of this disorder is unresponsive to TSH. Moreover, we found that the mutants were transmitted in an autosomal recessive manner. PMID:1904088
6. Cortical and thalamic connectivity of the auditory anterior ectosylvian cortex of early-deaf cats: Implications for neural mechanisms of crossmodal plasticity.
Meredith, M Alex; Clemo, H Ruth; Corley, Sarah B; Chabot, Nicole; Lomber, Stephen G
2016-03-01
Early hearing loss leads to crossmodal plasticity in regions of the cerebrum that are dominated by acoustical processing in hearing subjects. Until recently, little has been known of the connectional basis of this phenomenon. One region whose crossmodal properties are well-established is the auditory field of the anterior ectosylvian sulcus (FAES) in the cat, where neurons are normally responsive to acoustic stimulation and its deactivation leads to the behavioral loss of accurate orienting toward auditory stimuli. However, in early-deaf cats, visual responsiveness predominates in the FAES and its deactivation blocks accurate orienting behavior toward visual stimuli. For such crossmodal reorganization to occur, it has been presumed that novel inputs or increased projections from non-auditory cortical areas must be generated, or that existing non-auditory connections were 'unmasked.' These possibilities were tested using tracer injections into the FAES of adult cats deafened early in life (and hearing controls), followed by light microscopy to localize retrogradely labeled neurons. Surprisingly, the distribution of cortical and thalamic afferents to the FAES was very similar among early-deaf and hearing animals. No new visual projection sources were identified and visual cortical connections to the FAES were comparable in projection proportions. These results support an alternate theory for the connectional basis for cross-modal plasticity that involves enhanced local branching of existing projection terminals that originate in non-auditory as well as auditory cortices. PMID:26724756
7. Spectral and Temporal Acoustic Features Modulate Response Irregularities within Primary Auditory Cortex Columns.
Andres Carrasco
Full Text Available Assemblies of vertically connected neurons in the cerebral cortex form information processing units (columns that participate in the distribution and segregation of sensory signals. Despite well-accepted models of columnar architecture, functional mechanisms of inter-laminar communication remain poorly understood. Hence, the purpose of the present investigation was to examine the effects of sensory information features on columnar response properties. Using acute recording techniques, extracellular response activity was collected from the right hemisphere of eight mature cats (felis catus. Recordings were conducted with multichannel electrodes that permitted the simultaneous acquisition of neuronal activity within primary auditory cortex columns. Neuronal responses to simple (pure tones, complex (noise burst and frequency modulated sweeps, and ecologically relevant (con-specific vocalizations acoustic signals were measured. Collectively, the present investigation demonstrates that despite consistencies in neuronal tuning (characteristic frequency, irregularities in discharge activity between neurons of individual A1 columns increase as a function of spectral (signal complexity and temporal (duration acoustic variations.
8. Encoding of Temporal Information by Timing, Rate, and Place in Cat Auditory Cortex
Imaizumi, Kazuo; Priebe, Nicholas J.; Sharpee, Tatyana O.; Cheung, Steven W.; Schreiner, Christoph E.
2010-01-01
A central goal in auditory neuroscience is to understand the neural coding of species-specific communication and human speech sounds. Low-rate repetitive sounds are elemental features of communication sounds, and core auditory cortical regions have been implicated in processing these information-bearing elements. Repetitive sounds could be encoded by at least three neural response properties: 1) the event-locked spike-timing precision, 2) the mean firing rate, and 3) the interspike interval (...
9. Cats
... those experienced by humans. Cats that hunt wild rodents and rabbits in the western, particularly the southwestern, ... caused by a fungus that can infect skin, hair, and nails of both people and animals. Ringworm ...
10. Enhanced representation of spectral contrasts in the primary auditory cortex
Nicolas eCatz
2013-06-01
Full Text Available The role of early auditory processing may be to extract some elementary features from an acoustic mixture in order to organize the auditory scene. To accomplish this task, the central auditory system may rely on the fact that sensory objects are often composed of spectral edges, i.e. regions where the stimulus energy changes abruptly over frequency. The processing of acoustic stimuli may benefit from a mechanism enhancing the internal representation of spectral edges. While the visual system is thought to rely heavily on this mechanism (enhancing spatial edges, it is still unclear whether a related process plays a significant role in audition. We investigated the cortical representation of spectral edges, using acoustic stimuli composed of multi-tone pips whose time-averaged spectral envelope contained suppressed or enhanced regions. Importantly, the stimuli were designed such that neural responses properties could be assessed as a function of stimulus frequency during stimulus presentation. Our results suggest that the representation of acoustic spectral edges is enhanced in the auditory cortex, and that this enhancement is sensitive to the characteristics of the spectral contrast profile, such as depth, sharpness and width. Spectral edges are maximally enhanced for sharp contrast and large depth. Cortical activity was also suppressed at frequencies within the suppressed region. To note, the suppression of firing was larger at frequencies nearby the lower edge of the suppressed region than at the upper edge. Overall, the present study gives critical insights into the processing of spectral contrasts in the auditory system.
11. Sensory Responses during Sleep in Primate Primary and Secondary Auditory Cortex
Issa, Elias B.; Wang, Xiaoqin
2008-01-01
Most sensory stimuli do not reach conscious perception during sleep. It has been thought that the thalamus prevents the relay of sensory information to cortex during sleep, but the consequences for cortical responses to sensory signals in this physiological state remain unclear. We recorded from two auditory cortical areas downstream of the thalamus in naturally sleeping marmoset monkeys. Single neurons in primary auditory cortex either increased or decreased their responses during sleep comp...
12. Measuring the dynamics of neural responses in primary auditory cortex
Depireux, Didier A; Simon, Jonathan Z.; Shamma, Shihab A.
1998-01-01
We review recent developments in the measurement of the dynamics of the response properties of auditory cortical neurons to broadband sounds, which is closely related to the perception of timbre. The emphasis is on a method that characterizes the spectro-temporal properties of single neurons to dynamic, broadband sounds, akin to the drifting gratings used in vision. The method treats the spectral and temporal aspects of the response on an equal footing.
13. Auditory brain-stem evoked potentials in cat after kainic acid induced neuronal loss. I. Superior olivary complex.
Zaaroor, M; Starr, A
1991-01-01
Auditory brain-stem potentials (ABRs) were studied in cats for up to 45 days after kainic acid had been injected unilaterally or bilaterally into the superior olivary complex (SOC) to produce neuronal destruction while sparing fibers of passage and the terminals of axons of extrinsic origin connecting to SOC neurons. The components of the ABR in cat were labeled by their polarity at the vertex (P, for positive) and their order of appearance (the arabic numerals 1, 2, etc.). Component P1 can be further subdivided into 2 subcomponents labeled P1a and P1b. The correspondences we have assumed between the ABR components in cat and man are indicated by providing a Roman numeral designation for the human component in parentheses following the feline notation, e.g., P4 (V). With bilateral SOC destruction, there was a significant and marked attenuation of waves P2 (III), P3 (IV), P4 (V), P5 (VI), and the sustained potential shift (SPS) amounting to as much as 80% of preoperative values. Following unilateral SOC destruction the attenuation of many of these same ABR components, in response to stimulation of either ear, was up to 50%. No component of the ABR was totally abolished even when the SOC was lesioned 100% bilaterally. In unilaterally lesioned cats with extensive neuronal loss (greater than 75%) the latencies of the components beginning at P3 (IV) were delayed to stimulation of the ear ipsilateral to the injection site but not to stimulation of the ear contralateral to the injection. Binaural interaction components of the ABR were affected in proportion to the attenuation of the ABR. These results are compatible with multiple brain regions contributing to the generation of the components of the ABR beginning with P2 (III) and that components P3 (IV), P4 (V), and P5 (VI) and the sustained potential shift depend particularly on the integrity of the neurons of the SOC bilaterally. The neurons of the lateral subdivision (LSO) and the medial nucleus of the trapezoid body
14. Outcome and prognostic indicators in 20 cats with surgically treated primary lung tumors.
Maritato, Karl C; Schertel, Eric R; Kennedy, Shawn C; Dudley, Robert; Lamm, Catherine; Barnhart, Matthew; Kass, Phillip
2014-12-01
The purpose of this retrospective study of 20 client-owned cats was to describe the clinical signs, surgical interventions, histological features, stage and treatments of primary lung tumors removed by surgical excision, and to determine which factors significantly influence survival. Any cat that underwent surgical resection of a primary lung tumor between 2000 and 2007 was included in the study. Patient records were reviewed and signalment, clinical signs, preoperative diagnostics, surgical findings and histopathological results recorded. Histological reports were reviewed and scored using World Health Organization criteria. The Kaplan-Meier test was used to evaluate each potential prognostic factor with survival. Twenty cats met the inclusion criteria. The presence of clinical signs (such as dyspnea) at the time of diagnosis (P = 0.032), pleural effusion (P = 0.046), stage M1 (P = 0.015), and moderately and poorly differentiated tumors on histopathology (P = 0.011) were factors that were significantly correlated with reduced survival times. The median survival time of the 20 cats was 11 days. Cats presenting with no clinical signs had a median survival time of 578 days post-surgery vs 4 days post-surgery when presented with clinical signs. Cats staged T1N0M0 lived longer than cats at other stages (P = 0.044). Of the cats that survived to the time of suture removal, median survival time was 64 days. The results indicate that the presence of clinical signs, pleural effusion, moderately and poorly differentiated tumors on histopathology, evidence of metastasis and any stage beyond T1N0M0 are negative prognostic indicators for cats with primary lung tumors. The findings demonstrate that cats that presented with clinical signs, pleural effusion, any stage other than T1N0M0, or moderately and poorly differentiated tumors on histopathology had a poor prognosis. Therefore, extensive preoperative diagnostics, including computed tomography scans, should be performed
15. Auditory brain-stem evoked potentials in cat after kainic acid induced neuronal loss. II. Cochlear nucleus.
Zaaroor, M; Starr, A
1991-01-01
Auditory brain-stem potentials (ABRs) were studied in cats for up to 6 weeks after kainic acid had been injected unilaterally into the cochlear nucleus (CN) producing extensive neuronal destruction. The ABR components were labeled by the polarity at the vertex (P, for positive) and their order of appearance (the arabic numerals 1, 2, etc.). Component P1 can be further subdivided into 2 subcomponents, P1a and P1b. The assumed correspondence between the ABR components in cat and man is indicated by providing human Roman numeral designations in parentheses following the feline notation, e.g., P2 (III). To stimulation of the ear ipsilateral to the injection, the ABR changes consisted of a loss of components P2 (III) and P3 (IV), and an attenuation and prolongation of latency of components P4 (V) and P5 (VI). The sustained potential shift from which the components arose was not affected. Wave P1a (I) was also slightly but significantly attenuated compatible with changes of excitability of nerve VIII in the cochlea secondary to cochlear nucleus destruction. Unexpectedly, to stimulation of the ear contralateral to the injection side, waves P2 (III), P3 (IV), and P4 (V) were also attenuated and delayed in latency but to a lesser degree than to stimulation of the ear ipsilateral to the injection. Changes in binaural interaction of the ABR following cochlear nucleus lesions were similar to those produced in normal animals by introducing a temporal delay of the input to one ear. The results of the present set of studies using kainic acid to induce neuronal loss in auditory pathway when combined with prior lesion and recording experiments suggest that each of the components of the ABR requires the integrity of an anatomically diffuse system comprising a set of neurons, their axons, and the neurons on which they terminate. Disruption of any portion of the system will alter the amplitude and/or the latency of that component. PMID:1716569
16. Synaptic Basis for Cross-modal Plasticity: Enhanced Supragranular Dendritic Spine Density in Anterior Ectosylvian Auditory Cortex of the Early Deaf Cat.
Clemo, H Ruth; Lomber, Stephen G; Meredith, M Alex
2016-04-01
In the cat, the auditory field of the anterior ectosylvian sulcus (FAES) is sensitive to auditory cues and its deactivation leads to orienting deficits toward acoustic, but not visual, stimuli. However, in early deaf cats, FAES activity shifts to the visual modality and its deactivation blocks orienting toward visual stimuli. Thus, as in other auditory cortices, hearing loss leads to cross-modal plasticity in the FAES. However, the synaptic basis for cross-modal plasticity is unknown. Therefore, the present study examined the effect of early deafness on the density, distribution, and size of dendritic spines in the FAES. Young cats were ototoxically deafened and raised until adulthood when they (and hearing controls) were euthanized, the cortex stained using Golgi-Cox, and FAES neurons examined using light microscopy. FAES dendritic spine density averaged 0.85 spines/μm in hearing animals, but was significantly higher (0.95 spines/μm) in the early deaf. Size distributions and increased spine density were evident specifically on apical dendrites of supragranular neurons. In separate tracer experiments, cross-modal cortical projections were shown to terminate predominantly within the supragranular layers of the FAES. This distributional correspondence between projection terminals and dendritic spine changes indicates that cross-modal plasticity is synaptically based within the supragranular layers of the early deaf FAES. PMID:25274986
17. Cobalt labelling of single primary auditory neurones: An alternative to HRP
Köppl, Christine; Gleich, Otto
1988-01-01
We have labelled single, primary auditory neurones in three reptile and one bird species. After functional characterization of the neurones, hexamminecobaltic chloride was iontophoretically injected through the recording micropipette. Precipitation of cobalt sulfide followed by silver intensification of the cochlear duct as a whole-mount preparation revealed stained neurones in over 90% of cases. This method has several advantages over labelling with HRP.
18. Asymmetry in primary auditory cortex activity in tinnitus patients and controls
Geven, L. I.; de Kleine, E.; Willemsen, A. T. M.; van Dijk, P.
2014-01-01
Tinnitus is a bothersome phantom sound percept and its neural correlates are not yet disentangled. Previously published papers, using [(18)F]-fluoro-deoxyglucose positron emission tomography (FDG-PET), have suggested an increased metabolism in the left primary auditory cortex in tinnitus patients. T
19. Neural Resolution of Formant Frequencies in the Primary Auditory Cortex of Rats
Honey, Christian; Schnupp, Jan
2015-01-01
Pulse-resonance sounds play an important role in animal communication and auditory object recognition, yet very little is known about the cortical representation of this class of sounds. In this study we shine light on one simple aspect: how well does the firing rate of cortical neurons resolve resonant (“formant”) frequencies of vowel-like pulse-resonance sounds. We recorded neural responses in the primary auditory cortex (A1) of anesthetized rats to two-formant pulse-resonance sounds, and e...
20. Primary central nervous system T-cell lymphoma mimicking meningoencephalomyelitis in a cat.
Guil-Luna, Silvia; Carrasco, Librado; Gómez-Laguna, Jaime; Hilbe, Monika; Mínguez, Juan J; Köhler, Kernt; de las Mulas, Juana Martín
2013-06-01
A cat was presented with right head tilt and circling. The lack of expression of virus antigens did not support the postmortem diagnosis of encephalomyelitis pointing to a diffuse primary central nervous system T-cell lymphoma on the basis of CD3 and CD45R co-expression with absence of CD79α staining. PMID:24155454
1. Classification of primary hepatic tumours in the cat
van Sprundel, Renee G H M; van den Ingh, Ted S G A M; Guscetti, Franco; Kershaw, Olivia; van Wolferen, Monique E; Rothuizen, Jan; Spee, Bart
2014-01-01
Hepatic tumours in dogs have recently been re-classified to follow a revised human classification system that takes account of identified hepatic progenitor cells. This study investigated the presence and relative frequency of morphological types of feline primary hepatic neoplasms and aimed to dete
2. Effect of high-dose ciclosporin on the immune response to primary and booster vaccination in immunocompetent cats.
Roberts, Elizabeth S; VanLare, Karen A; Roycroft, Linda M; King, Stephen
2015-02-01
Ciclosporin (Atopica oral solution for cats 100 mg/ml; Novartis Animal Health) was recently approved for use in cats with feline hypersensitivity dermatitis. The immunosuppressant effect of ciclosporin on the ability of cats to mount an immune response following vaccination was determined. Thirty-two healthy, immunocompetent adult cats (16 cats/group) were treated with either ciclosporin for 56 days at a dose of 24 mg/kg once daily or sham dosed. Prior to treatment, cats had an adequate antibody response to primary vaccination against feline calicivirus (FCV), feline herpesvirus-1 (FHV-1), feline panleukopenia virus (FPV), feline leukemia virus (FeLV) and rabies. Booster vaccination or novel vaccination with feline immunodeficiency virus (FIV) was administered 28 days after initiation of treatment with ciclosporin. There were no differences between the ciclosporin-treated and control cats for FCV and FPV antibody titers following booster vaccination. There were delays/reductions in antibody response to FHV-1, FeLV and rabies in treated cats; however, adequate protection was achieved in response to all booster vaccinations. Following primary vaccination with FIV, control cats showed a response, but treated cats showed no antibody production. Adverse events commonly associated with ciclosporin treatment, including diarrhea/loose stool, vomiting, salivation and regurgitation, were reported. In adult cats treated with 24 mg/kg/day of ciclosporin (more than three times the therapeutic dose), vaccine titer levels were adequate for protection following booster vaccination. In contrast, treated cats failed to mount a humoral response to a novel (FIV) vaccination, suggesting that memory B-cell immune responses remain intact during repeated high-dose ciclosporin administration in cats, but that primary immune responses are impaired. PMID:24820998
3. Neural Representation of Concurrent Vowels in Macaque Primary Auditory Cortex123
Micheyl, Christophe; Steinschneider, Mitchell
2016-01-01
Abstract Successful speech perception in real-world environments requires that the auditory system segregate competing voices that overlap in frequency and time into separate streams. Vowels are major constituents of speech and are comprised of frequencies (harmonics) that are integer multiples of a common fundamental frequency (F0). The pitch and identity of a vowel are determined by its F0 and spectral envelope (formant structure), respectively. When two spectrally overlapping vowels differing in F0 are presented concurrently, they can be readily perceived as two separate “auditory objects” with pitches at their respective F0s. A difference in pitch between two simultaneous vowels provides a powerful cue for their segregation, which in turn, facilitates their individual identification. The neural mechanisms underlying the segregation of concurrent vowels based on pitch differences are poorly understood. Here, we examine neural population responses in macaque primary auditory cortex (A1) to single and double concurrent vowels (/a/ and /i/) that differ in F0 such that they are heard as two separate auditory objects with distinct pitches. We find that neural population responses in A1 can resolve, via a rate-place code, lower harmonics of both single and double concurrent vowels. Furthermore, we show that the formant structures, and hence the identities, of single vowels can be reliably recovered from the neural representation of double concurrent vowels. We conclude that A1 contains sufficient spectral information to enable concurrent vowel segregation and identification by downstream cortical areas.
4. Wiener-Volterra characterization of neurons in primary auditory cortex using poisson-distributed impulse train inputs.
Pienkowski, Martin; Shaw, Greg; Eggermont, Jos J
2009-06-01
An extension of the Wiener-Volterra theory to a Poisson-distributed impulse train input was used to characterize the temporal response properties of neurons in primary auditory cortex (AI) of the ketamine-anesthetized cat. Both first- and second-order "Poisson-Wiener" (PW) models were tested on their predictions of temporal modulation transfer functions (tMTFs), which were derived from extracellular spike responses to periodic click trains with click repetition rates of 2-64 Hz. Second-order (i.e., nonlinear) PW fits to the measured tMTFs could be described as very good in a majority of cases (e.g., predictability >or=80%) and were almost always superior to first-order (i.e., linear) fits. In all sampled neurons, second-order PW kernels showed strong compressive nonlinearities (i.e., a depression of the impulse response) but never expansive nonlinearities (i.e., a facilitation of the impulse response). In neurons with low-pass tMTFs, the depression decayed exponentially with the interstimulus lag, whereas in neurons with band-pass tMTFs, the depression was typically double-peaked, and the second peak occurred at a lag that correlated with the neuron's best modulation frequency. It appears that modulation-tuning in AI arises in part from an interplay of two nonlinear processes with distinct time courses. PMID:19321635
5. Multi-Scale Entrainment of Coupled Neuronal Oscillations in Primary Auditory Cortex.
O'Connell, M N; Barczak, A; Ross, D; McGinnis, T; Schroeder, C E; Lakatos, P
2015-01-01
Earlier studies demonstrate that when the frequency of rhythmic tone sequences or streams is task relevant, ongoing excitability fluctuations (oscillations) of neuronal ensembles in primary auditory cortex (A1) entrain to stimulation in a frequency dependent way that sharpens frequency tuning. The phase distribution across A1 neuronal ensembles at time points when attended stimuli are predicted to occur reflects the focus of attention along the spectral attribute of auditory stimuli. This study examined how neuronal activity is modulated if only the temporal features of rhythmic stimulus streams are relevant. We presented macaques with auditory clicks arranged in 33 Hz (gamma timescale) quintets, repeated at a 1.6 Hz (delta timescale) rate. Such multi-scale, hierarchically organized temporal structure is characteristic of vocalizations and other natural stimuli. Monkeys were required to detect and respond to deviations in the temporal pattern of gamma quintets. As expected, engagement in the auditory task resulted in the multi-scale entrainment of delta- and gamma-band neuronal oscillations across all of A1. Surprisingly, however, the phase-alignment, and thus, the physiological impact of entrainment differed across the tonotopic map in A1. In the region of 11-16 kHz representation, entrainment most often aligned high excitability oscillatory phases with task-relevant events in the input stream and thus resulted in response enhancement. In the remainder of the A1 sites, entrainment generally resulted in response suppression. Our data indicate that the suppressive effects were due to low excitability phase delta oscillatory entrainment and the phase amplitude coupling of delta and gamma oscillations. Regardless of the phase or frequency, entrainment appeared stronger in left A1, indicative of the hemispheric lateralization of auditory function. PMID:26696866
6. Multi-scale entrainment of coupled neuronal oscillations in primary auditory cortex.
Monica Noelle O'Connell
2015-12-01
Full Text Available Earlier studies demonstrate that when the frequency of rhythmic tone sequences or streams is task relevant, ongoing excitability fluctuations (oscillations of neuronal ensembles in primary auditory cortex (A1 entrain to stimulation in a frequency dependent way that sharpens frequency tuning. The phase distribution across A1 neuronal ensembles at time points when attended stimuli are predicted to occur reflects the focus of attention along the spectral attribute of auditory stimuli. This study examined how neuronal activity is modulated if only the temporal features of rhythmic stimulus streams are relevant. We presented macaques with auditory clicks arranged in 33 Hz (gamma timescale quintets, repeated at a 1.6 Hz (delta timescale rate. Such multi-scale, hierarchically organized temporal structure is characteristic of vocalizations and other natural stimuli. Monkeys were required to detect and respond to deviations in the temporal pattern of gamma quintets. As expected, engagement in the auditory task resulted in the multi-scale entrainment of delta- and gamma-band neuronal oscillations across all of A1. Surprisingly, however, the phase-alignment, and thus, the physiological impact of entrainment differed across the tonotopic map in A1. In the region of 11-16 kHz representation, entrainment most often aligned high excitability oscillatory phases with task-relevant events in the input stream and thus resulted in response enhancement. In the remainder of the A1 sites, entrainment generally resulted in response suppression. Our data indicate that the suppressive effects were due to low excitability phase delta oscillatory entrainment and the phase amplitude coupling of delta and gamma oscillations. Regardless of the phase or frequency, entrainment appeared stronger in left A1, indicative of the hemispheric lateralization of auditory function.
7. Directional tunings independent of orientation in the primary visual cortex of the cat
陈垚; 李兵; 李宝旺; 刁云程
2001-01-01
A family of moving ‘random-line' patterns was developed and used to study the directional tuning of 91 single units in cat primary visual cortex (V1). The results suggest that, in addition to the well-known orientation-dependent mechanism, there is also some kind of orientation-independent mechanism underlying the direction selectivity. The directional tuning of the neurons varies in accordance with the increase of orientation or non-orientation element in the stimulus.
8. Neural Resolution of Formant Frequencies in the Primary Auditory Cortex of Rats.
Honey, Christian; Schnupp, Jan
2015-01-01
Pulse-resonance sounds play an important role in animal communication and auditory object recognition, yet very little is known about the cortical representation of this class of sounds. In this study we shine light on one simple aspect: how well does the firing rate of cortical neurons resolve resonant ("formant") frequencies of vowel-like pulse-resonance sounds. We recorded neural responses in the primary auditory cortex (A1) of anesthetized rats to two-formant pulse-resonance sounds, and estimated their formant resolving power using a statistical kernel smoothing method which takes into account the natural variability of cortical responses. While formant-tuning functions were diverse in structure across different penetrations, most were sensitive to changes in formant frequency, with a frequency resolution comparable to that reported for rat cochlear filters. PMID:26252382
9. Acquisition, Analyses and Interpretation of fMRI Data: A Study on the Effective Connectivity in Human Primary Auditory Cortices
A study on the effective connectivity characteristics in auditory cortices was conducted on five healthy Malay male subjects with the age of 20 to 40 years old using functional magnetic resonance imaging (fMRI), statistical parametric mapping (SPM5) and dynamic causal modelling (DCM). A silent imaging paradigm was used to reduce the scanner sound artefacts on functional images. The subjects were instructed to pay attention to the white noise stimulus binaurally given at intensity level of 70 dB higher than the hearing level for normal people. Functional specialisation was studied using Matlab-based SPM5 software by means of fixed effects (FFX), random effects (RFX) and conjunction analyses. Individual analyses on all subjects indicate asymmetrical bilateral activation between the left and right auditory cortices in Brodmann areas (BA)22, 41 and 42 involving the primary and secondary auditory cortices. The three auditory areas in the right and left auditory cortices are selected for the determination of the effective connectivity by constructing 9 network models. The effective connectivity is determined on four out of five subjects with the exception of one subject who has the BA22 coordinates located too far from BA22 coordinates obtained from group analysis. DCM results showed the existence of effective connectivity between the three selected auditory areas in both auditory cortices. In the right auditory cortex, BA42 is identified as input centre with unidirectional parallel effective connectivities of BA42→BA41and BA42→BA22. However, for the left auditory cortex, the input is BA41 with unidirectional parallel effective connectivities of BA41→BA42 and BA41→BA22. The connectivity between the activated auditory areas suggests the existence of signal pathway in the auditory cortices even when the subject is listening to noise. (author)
10. Perinatal exposure to a noncoplanar polychlorinated biphenyl alters tonotopy, receptive fields, and plasticity in rat primary auditory cortex
Kenet, T; Froemke, R. C.; Schreiner, C. E.; Pessah, I N; Merzenich, M. M.
2007-01-01
Noncoplanar polychlorinated biphenyls (PCBs) are widely dispersed in human environment and tissues. Here, an exemplar noncoplanar PCB was fed to rat dams during gestation and throughout three subsequent nursing weeks. Although the hearing sensitivity and brainstem auditory responses of pups were normal, exposure resulted in the abnormal development of the primary auditory cortex (A1). A1 was irregularly shaped and marked by internal nonresponsive zones, its topographic organization was grossl...
11. IMPAIRED PROCESSING IN THE PRIMARY AUDITORY CORTEX OF AN ANIMAL MODEL OF AUTISM
Renata eAnomal
2015-11-01
Full Text Available Autism is a neurodevelopmental disorder clinically characterized by deficits in communication, lack of social interaction and, repetitive behaviors with restricted interests. A number of studies have reported that sensory perception abnormalities are common in autistic individuals and might contribute to the complex behavioral symptoms of the disorder. In this context, hearing incongruence is particularly prevalent. Considering that some of this abnormal processing might stem from the unbalance of inhibitory and excitatory drives in brain circuitries, we used an animal model of autism induced by valproic acid (VPA during pregnancy in order to investigate the tonotopic organization of the primary auditory cortex (AI and its local inhibitory circuitry. Our results show that VPA rats have distorted primary auditory maps with over-representation of high frequencies, broadly tuned receptive fields and higher sound intensity thresholds as compared to controls. However, we did not detect differences in the number of parvalbumin-positive interneurons in AI of VPA and control rats. Altogether our findings show that neurophysiological impairments of hearing perception in this autism model occur independently of alterations in the number of parvalbumin-expressing interneurons. These data support the notion that fine circuit alterations, rather than gross cellular modification, could lead to neurophysiological changes in the autistic brain.
12. Hierarchical computation in the canonical auditory cortical circuit
Atencio, Craig A.; Sharpee, Tatyana O.; Schreiner, Christoph E.
2009-01-01
Sensory cortical anatomy has identified a canonical microcircuit underlying computations between and within layers. This feed-forward circuit processes information serially from granular to supragranular and to infragranular layers. How this substrate correlates with an auditory cortical processing hierarchy is unclear. We recorded simultaneously from all layers in cat primary auditory cortex (AI) and estimated spectrotemporal receptive fields (STRFs) and associated nonlinearities. Spike-trig...
13. Stimulus-invariant processing and spectrotemporal reverse correlation in primary auditory cortex.
Klein, David J; Simon, Jonathan Z; Depireux, Didier A; Shamma, Shihab A
2006-04-01
The spectrotemporal receptive field (STRF) provides a versatile and integrated, spectral and temporal, functional characterization of single cells in primary auditory cortex (AI). In this paper, we explore the origin of, and relationship between, different ways of measuring and analyzing an STRF. We demonstrate that STRFs measured using a spectrotemporally diverse array of broadband stimuli-such as dynamic ripples, spectrotemporally white noise, and temporally orthogonal ripple combinations (TORCs)-are very similar, confirming earlier findings that the STRF is a robust linear descriptor of the cell. We also present a new deterministic analysis framework that employs the Fourier series to describe the spectrotemporal modulations contained in the stimuli and responses. Additional insights into the STRF measurements, including the nature and interpretation of measurement errors, is presented using the Fourier transform, coupled to singular-value decomposition (SVD), and variability analyses including bootstrap. The results promote the utility of the STRF as a core functional descriptor of neurons in AI. PMID:16518572
14. Electrophysiological mismatch response recorded in awake pigeons from the avian functional equivalent of the primary auditory cortex.
Schall, Ulrich; Müller, Bernhard W; Kärgel, Christian; Güntürkün, Onur
2015-03-25
The neural response to occasional variations in acoustic stimuli in a regular sequence of sounds generates an N-methyl-D-aspartate receptor-modulated event-related potential in primates and rodents in the primary auditory cortex known as mismatch negativity (MMN). The current study investigated MMN in pigeons (Columba livia L) through intracranial recordings from Field L of the caudomedial nidopallium, the avian functional equivalent of the mammalian primary auditory cortex. Auditory evoked field potentials were recorded from awake birds using a low-frequency (800 Hz) and high-frequency (1400 Hz) deviant auditory oddball procedure with deviant-as-standard (flip-flop design) and multiple-standard control conditions. An MMN-like field potential was recorded and blocked with systemic 5 mg/kg ketamine administration. Our results are similar to human and rodent findings of an MMN-like event-related potential in birds suggestive of similar auditory sensory memory mechanisms in birds and mammals that are homologue from a common ancestor 300 million years ago or resulted from convergent evolution. PMID:25646582
15. TNF-A Levels throughout the Critical Period for Experience-Dependent Plasticity in the Rat Primary Auditory Cortex
Man, WH; Madeira, Caroline; Zhou, Xiaoming; Merzenich, Michael M; Panizzutti, Rogerio
2015-01-01
Tumor necrosis factor- alpha (TNF-α) is likely to play a role in brain plasticity. To determine whether TNF-α levels change throughout a critical period of experience-dependent brain plasticity, we assessed these levels in the primary auditory cortex of rats before, during and after the critical per
16. The First Estimates of Marbled Cat Pardofelis marmorata Population Density from Bornean Primary and Selectively Logged Forest
Hearn, Andrew J.; Ross, Joanna; Bernard, Henry; Bakar, Soffian Abu; Hunter, Luke T. B.; Macdonald, David W.
2016-01-01
The marbled cat Pardofelis marmorata is a poorly known wild cat that has a broad distribution across much of the Indomalayan ecorealm. This felid is thought to exist at low population densities throughout its range, yet no estimates of its abundance exist, hampering assessment of its conservation status. To investigate the distribution and abundance of marbled cats we conducted intensive, felid-focused camera trap surveys of eight forest areas and two oil palm plantations in Sabah, Malaysian Borneo. Study sites were broadly representative of the range of habitat types and the gradient of anthropogenic disturbance and fragmentation present in contemporary Sabah. We recorded marbled cats from all forest study areas apart from a small, relatively isolated forest patch, although photographic detection frequency varied greatly between areas. No marbled cats were recorded within the plantations, but a single individual was recorded walking along the forest/plantation boundary. We collected sufficient numbers of marbled cat photographic captures at three study areas to permit density estimation based on spatially explicit capture-recapture analyses. Estimates of population density from the primary, lowland Danum Valley Conservation Area and primary upland, Tawau Hills Park, were 19.57 (SD: 8.36) and 7.10 (SD: 1.90) individuals per 100 km2, respectively, and the selectively logged, lowland Tabin Wildlife Reserve yielded an estimated density of 10.45 (SD: 3.38) individuals per 100 km2. The low detection frequencies recorded in our other survey sites and from published studies elsewhere in its range, and the absence of previous density estimates for this felid suggest that our density estimates may be from the higher end of their abundance spectrum. We provide recommendations for future marbled cat survey approaches. PMID:27007219
17. Temporal overlaps of feral cats with prey and competitors in primary and human-altered habitats on Bohol Island, Philippines.
Bogdan, Vlastimil; Jůnek, Tomáš; Jůnková Vymyslická, Pavla
2016-01-01
The vertebrate fauna of the Philippines, known for its diversity and high proportion of endemic species, comprises mainly small- to medium-sized forms with a few large exceptions. As with other tropical ecosystems, the major threats to wildlife are habitat loss, hunting and invasive species, of which the feral cat (Felis catus) is considered the most damaging. Our camera-trapping study focused on a terrestrial vertebrate species inventory on Bohol Island and tempo-spatial co-occurrences of feral cats with their prey and competitors. The survey took place in the Rajah Sikatuna Protected Landscape, and we examined the primary rainforest, its border with agricultural land, and rural areas in the vicinity of villages. Altogether, over 2,885 trap days we captured 30 species of vertebrates-10 mammals (including Sus philippensis), 19 birds and one reptile, Varanus cumingi. We trapped 81.8% of expected vertebrates. Based on the number of events, the most frequent native species was the barred rail (Gallirallus torquatus). The highest overlap in diel activity between cats and potential prey was recorded with rodents in rural areas (Δ = 0.62); the lowest was in the same habitat with ground-dwelling birds (Δ = 0.40). Cat activity was not recorded inside the rainforest; in other habitats their diel activity pattern differed. The cats' activity declined in daylight in the proximity of humans, while it peaked at the transition zone between rainforest and fields. Both rodents and ground-dwelling birds exhibited a shift in activity levels between sites where cats were present or absent. Rodents tend to become active by day in cat-free habitats. No cats' temporal response to co-occurrences of civets (Paradoxurus hermaphroditus and Viverra tangalunga) was found but cats in diel activity avoided domestic dogs (Canis lupus familiaris). Our first insight into the ecology of this invasive predator in the Philippines revealed an avoidance of homogeneous primary rainforest and a
18. Effect of Contrast on Visual Spatial Summation in Different Cell Categories in Cat Primary Visual Cortex.
Ke Chen
Full Text Available Multiple cell classes have been found in the primary visual cortex, but the relationship between cell types and spatial summation has seldom been studied. Parvalbumin-expressing inhibitory interneurons can be distinguished from pyramidal neurons based on their briefer action potential durations. In this study, we classified V1 cells into fast-spiking units (FSUs and regular-spiking units (RSUs and then examined spatial summation at high and low contrast. Our results revealed that the excitatory classical receptive field and the suppressive non-classical receptive field expanded at low contrast for both FSUs and RSUs, but the expansion was more marked for the RSUs than for the FSUs. For most V1 neurons, surround suppression varied as the contrast changed from high to low. However, FSUs exhibited no significant difference in the strength of suppression between high and low contrast, although the overall suppression decreased significantly at low contrast for the RSUs. Our results suggest that the modulation of spatial summation by stimulus contrast differs across populations of neurons in the cat primary visual cortex.
19. Ventral tegmental area activation promotes firing precision and strength through circuit inhibition in the primary auditory cortex
Yi Zhou
2014-01-01
The activation of the ventral tegmental area (VTA) can rebuild the tonotopic representation in the primary auditory cortex (A1), but the cellular mechanisms remain largely unknown. Here, we investigated the firing patterns and membrane potential dynamics of neurons in A1 under the influence of VTA activation using in vivo intracellular recording. We found that VTA activation can significantly reduce the variability of sound evoked responses and promote the firing precision and strength of A1 ...
20. Primary entropion in persian cats Entrópio primário em gatos persas
José Luiz Laus
1999-12-01
Full Text Available Entropion is defined as the inward rolling of the eyelid margin in which the eyelashes and eyelid hair (frequently the lower lateral lid rub the cornea. Etiologies may be congenital, spastic, or cicatricial. This condition usually causes epiphora, blepharospasm, photophobia, conjunctivitis, purulent discharge, corneal vascularization, pigmentation and ulceration, if not surgically treated. Congenital entropion commonly affects dogs and is frequently hereditary in some breeds, whereas cats are uncommonly affected. A predilection for the Persian breed to present primary entropion has been suggested. The authors report two cases of entropion in Persian cats referred to the Ophthalmology Section of Veterinary College of São Paulo State University - UNESP, Jaboticabal - SP / Brazil. First case: a male Persian cat, 2 years old, with a history of bilateral ocular irritation and purulent discharge for 8 months. Ophthalmic examination revealed epiphora, blepharospasm, photophobia, bilateral entropion affecting the whole length of the lower eyelids, conjunctivitis and purulent discharge. Second case: a male Persian cat, 1 year old, with a history of bilateral ocular irritation and purulent discharge for 3 weeks. At ophthalmic examination the animal was presenting epiphora, blepharospasm, photophobia, bilateral entropion affecting the whole length of the lower lids, conjunctivitis, purulent discharge, corneal vascularization, superficial ulceration and edema. The entropion persisted after topical anaestesia in both cats. Surgical treatment was similar in both cases, based on the modified Holtz-Celsus procedure. Grid keratotomy procedure was also performed in the second case. Both cats had a satisfactory clinic evolution which was confirmed few days after surgery.O entrópio é caracterizado por uma inversão da margem palpebral, na qual os cílios e os pêlos da pálpebra (freqüentemente a porção lateral da pálpebra inferior atritam a córnea. A
1. Characteristics of auditory processing disorder in primary school-aged children
Ferguson, Melanie A.
2014-01-01
The aims of this research were to identify and compare auditory processing, speech intelligibility, cognitive, listening, language and communication abilities in (i) typically developing, mainstream school (MS) children (n = 122) for direct comparison with (ii) children presenting to clinical services with auditory processing disorder (APD) (n = 19) or specific language impairment (SLI) (n = 22), and in (iii) a large population sample (n = 1469) who were categorised by their functional listen...
2. Bimodal stimulus timing-dependent plasticity in primary auditory cortex is altered after noise exposure with and without tinnitus.
Basura, Gregory J; Koehler, Seth D; Shore, Susan E
2015-12-01
Central auditory circuits are influenced by the somatosensory system, a relationship that may underlie tinnitus generation. In the guinea pig dorsal cochlear nucleus (DCN), pairing spinal trigeminal nucleus (Sp5) stimulation with tones at specific intervals and orders facilitated or suppressed subsequent tone-evoked neural responses, reflecting spike timing-dependent plasticity (STDP). Furthermore, after noise-induced tinnitus, bimodal responses in DCN were shifted from Hebbian to anti-Hebbian timing rules with less discrete temporal windows, suggesting a role for bimodal plasticity in tinnitus. Here, we aimed to determine if multisensory STDP principles like those in DCN also exist in primary auditory cortex (A1), and whether they change following noise-induced tinnitus. Tone-evoked and spontaneous neural responses were recorded before and 15 min after bimodal stimulation in which the intervals and orders of auditory-somatosensory stimuli were randomized. Tone-evoked and spontaneous firing rates were influenced by the interval and order of the bimodal stimuli, and in sham-controls Hebbian-like timing rules predominated as was seen in DCN. In noise-exposed animals with and without tinnitus, timing rules shifted away from those found in sham-controls to more anti-Hebbian rules. Only those animals with evidence of tinnitus showed increased spontaneous firing rates, a purported neurophysiological correlate of tinnitus in A1. Together, these findings suggest that bimodal plasticity is also evident in A1 following noise damage and may have implications for tinnitus generation and therapeutic intervention across the central auditory circuit. PMID:26289461
3. Altered Neural Responses to Sounds in Primate Primary Auditory Cortex during Slow-Wave Sleep
Issa, Elias B.; Wang, Xiaoqin
2011-01-01
How sounds are processed by the brain during sleep is an important question for understanding how we perceive the sensory environment in this unique behavioral state. While human behavioral data have indicated selective impairments of sound processing during sleep, brain imaging and neurophysiology studies have reported that overall neural activity in auditory cortex during sleep is surprisingly similar to that during wakefulness. This responsiveness to external stimuli leaves open the questi...
4. Discospondylitis in a cat
The incidence and causative agents of discospondylitis in cats are unknown. This report describes a cat with radiologic changes consistent with discospondylitis and concurrent urinary tract infection. As in dogs, discospondylitis should be the primary rule out for vertebral end plate lysis in cats
5. Trajectory of the main GABAergic interneuron populations from early development to old age in the rat primary auditory cortex
Lydia eOuellet
2014-06-01
Full Text Available In both humans and rodents, decline in cognitive function is a hallmark of the aging process, the basis for this decrease has yet to be fully characterized. However, using aged rodent models, deficits in auditory processing have been associated with significant decreases in inhibitory signaling attributed to a loss of GABAergic interneurons. Not only are these interneurons crucial for pattern detection and other large-scale population dynamics, but they have also been linked to mechanisms mediating plasticity and learning, making them a prime candidate for study and modelling of modifications to cortical communication pathways in neurodegenerative diseases. Using the rat primary auditory cortex (A1 as a model, we probed the known markers of GABAergic interneurons with immunohistological methods, using antibodies against gamma aminobutyric acid (GABA, parvalbumin (PV, somatostatin (SOM, calretinin (CR, vasoactive intestinal peptide (VIP, choline acetyltransferase (ChAT, neuropeptide Y (NPY and cholecystokinin (CCK to document the changes observed in interneuron populations across the rat’s lifespan. This analysis provided strong evidence that several but not all GABAergic neurons were affected by the aging process, showing most dramatic changes in expression of parvalbumin (PV and somatostatin (SOM expression. With this evidence, we show how understanding these trajectories of cell counts may be factored into a simple model to quantify changes in inhibitory signalling across the course of life, which may be applied as a framework for creating more advanced simulations of interneuronal implication in normal cerebral processing, normal aging, or pathological processes.
6. The Effects of Aircraft Noise on the Auditory Language Processing Abilities of English First Language Primary School Learners in Durban, South Africa
Hollander, Cara; de Andrade, Victor Manuel
2014-01-01
Schools located near to airports are exposed to high levels of noise which can cause cognitive, health, and hearing problems. Therefore, this study sought to explore whether this noise may cause auditory language processing (ALP) problems in primary school learners. Sixty-one children attending schools exposed to high levels of noise were matched…
7. Interplay of orientation selectivity and the power of low- and high-gamma bands in the cat primary visual cortex.
Bharmauria, Vishal; Bachatene, Lyes; Ouelhazi, Afef; Cattan, Sarah; Chanauria, Nayan; Etindele-Sosso, Faustin Armel; Rouat, Jean; Molotchnikoff, Stéphane
2016-05-01
Gamma oscillations are ubiquitous in brain and are believed to be inevitable for information processing in brain. Here, we report that distinct bands (low, 30-40Hz and high gamma, 60-80Hz) of stimulus-triggered gamma oscillations are systematically linked to the orientation selectivity index (OSI) of neurons in the cat primary visual cortex. The gamma-power is high for the highly selective neurons in the low-gamma band, whereas it is high for the broadly selective neurons in the high-gamma band. We suggest that the low-gamma band is principally implicated in feed-forward excitatory flow, whereas the high-gamma band governs the flow of this excitation. PMID:27033667
8. Cardiac Biomarkers in Hyperthyroid Cats
Sangster, Jodi Kirsten
2013-01-01
Background: Hyperthyroidism has substantial effects on the circulatory system. The cardiac biomarkers NT-proBNP and troponin I (cTNI) have proven useful in identifying cats with myocardial disease but have not been as extensively investigated in hyperthyroidism.Hypothesis: Plasma NT-proBNP and cTNI concentrations are higher in cats with primary cardiac disease than in cats with hyperthyroidism and higher in cats with hyperthyroidism than in healthy control cats.Animals: Twenty-three hyperthyr...
9. Cardiac Biomarkers in Hyperthyroid Cats
Sangster, J.K.; Panciera, D L; Abbott, J.A.; Zimmerman, K.C.; Lantis, A.C.
2013-01-01
Background Hyperthyroidism has substantial effects on the circulatory system. The cardiac biomarkers NT‐proBNP and troponin I (cTNI) have proven useful in identifying cats with myocardial disease but have not been extensively investigated in hyperthyroidism. Hypothesis Plasma NT‐proBNP and cTNI concentrations are higher in cats with primary myocardial disease than in cats with hyperthyroidism and higher in cats with hyperthyroidism than in healthy control cats. Animals Twenty‐three hyperthyro...
10. Auditory primary afferents in the starling: Correlation of function and morphology
Gleich, Otto
1989-01-01
Despite the independent evolution of birds and mammals, a number of structural similarities of their hearing organs have developed in parallel. By tracing the peripheral origin of functionally-characterized primary neurons, the present study demonstrates functional similarities between the respective hair cell populations of the hearing organs of birds and mammals. The space devoted to one octave on the starling’s basilar papilla is not constant over the whole length; rather it increases from...
11. ON AND OFF DOMAINS OF GENICULATE AFFERENTS IN CAT PRIMARY VISUAL CORTEX
Jin, J. Z.; Weng, C.; Yeh, C. I.; Gordon, J A; RUTHAZER, E.S.; Stryker, M.P.; Swadlow, H A; Alonso, J M
2007-01-01
On- and off-center geniculate afferents form two major channels of visual processing that are thought to converge in the primary visual cortex. However, humans with severely reduced on-responses can have normal visual acuity when tested in a white background, which indicates that off-channels can function relatively independently of on-channels under certain conditions. Consistent with this functional independence of channels, here we demonstrate that on- and off-center geniculate afferents s...
12. Supplementary motor area and primary auditory cortex activation in an expert break-dancer during the kinesthetic motor imagery of dance to music.
Olshansky, Michael P; Bar, Rachel J; Fogarty, Mary; DeSouza, Joseph F X
2015-01-01
The current study used functional magnetic resonance imaging to examine the neural activity of an expert dancer with 35 years of break-dancing experience during the kinesthetic motor imagery (KMI) of dance accompanied by highly familiar and unfamiliar music. The goal of this study was to examine the effect of musical familiarity on neural activity underlying KMI within a highly experienced dancer. In order to investigate this in both primary sensory and motor planning cortical areas, we examined the effects of music familiarity on the primary auditory cortex [Heschl's gyrus (HG)] and the supplementary motor area (SMA). Our findings reveal reduced HG activity and greater SMA activity during imagined dance to familiar music compared to unfamiliar music. We propose that one's internal representations of dance moves are influenced by auditory stimuli and may be specific to a dance style and the music accompanying it. PMID:25301352
13. Computed tomography of primary inflammatory brain disorders in dogs and cats
A retrospective study of 22 animals with histologically confirmed, primary inflammatory brain disease was undertaken to determine the value of computed tomography in such patients. The histologic diagnosis was confirmed at necropsy in 18 patients and by surgical biopsy in four. All affected animals had neurologic deficits; the most common presenting complaint was seizures. Abnormalities were identified on computed tomography images in 21 of the 22 patients. The abnormalities included ventricular changes, falcial deviation, edema, focal changes in parenchymal opacity, focal contrast enhancement, periventricular contrast enhancement, and a ring-like pattern of contrast enhancement. Many lesion types identified in this study, such as falcial deviation, changes in parenchymal opacity, and ring-pattern enhancement, have previously been associated with neoplasia. The abnormalities correlated well with the lesion localization predicted by neurologic examination and confirmed by surgery or necropsy. Although computed tomography findings were often judged to be compatible with inflammatory disease, they did not predict the type of pathologic process. The findings suggest that computed tomography is valuable in the evaluation of animals with primary inflammatory brain disorders, but differentiation of neoplasia from non-neoplastic diseases is not always possible
14. Computed tomographic aspects of primary brain tumors in dogs and cats
Over the years, the Veterinary Medicine has made great advances, enabling thus the diagnosis of many diseases. As a result of this new situation, there was an increased expectation of life of animals resulting in an increase in the number of clinical care of older animals. Thus, diseases considered unusual in the past, begin to be diagnosed more frequently, as is the case of brain damage. Recently, computed tomography has been widely used in Brazil as a tool to aid in the diagnosis of several diseases. This noninvasive imaging technique allows the identification and evaluation of lesions of central nervous tissue such as brain tumors. This provides information about the size, shape and location of the lesion, in addition to the magnitude of compression and invasion of adjacent structures by the tumor and its side effects (such as the peritumoral edema and hydrocephalus). The image obtained from computed tomography may suggest the presence of a certain type brain tumor, data of great importance for the prognosis and treatment of the animal. This review covers the computed tomography aspects of primary brain tumors such as meningiomas, astrocytomas, oligodendrogliomas, choroid plexus tumors and ependymomas. However, despite the computed tomography provide much information about the changes inside the skull; no way replace histopathological examination in determining the definitive diagnosis. (author)
15. Auditory Processing Disorders
Auditory Processing Disorders Auditory processing disorders (APDs) are referred to by many names: central auditory processing disorders , auditory perceptual disorders , and central auditory disorders . APDs ...
16. Cat Ownership Perception and Caretaking Explored in an Internet Survey of People Associated with Cats
Zito, Sarah; Vankan, Dianne; Bennett, Pauleen; Paterson, Mandy; Phillips, Clive J. C.
2015-01-01
People who feed cats that they do not perceive they own (sometimes called semi-owners) are thought to make a considerable contribution to unwanted cat numbers because the cats they support are generally not sterilized. Understanding people’s perception of cat ownership and the psychology underlying cat semi-ownership could inform approaches to mitigate the negative effects of cat semi-ownership. The primary aims of this study were to investigate cat ownership perception and to examine its ass...
17. Visual–auditory spatial processing in auditory cortical neurons
Bizley, Jennifer K.; King, Andrew J
2008-01-01
Neurons responsive to visual stimulation have now been described in the auditory cortex of various species, but their functions are largely unknown. Here we investigate the auditory and visual spatial sensitivity of neurons recorded in 5 different primary and non-primary auditory cortical areas of the ferret. We quantified the spatial tuning of neurons by measuring the responses to stimuli presented across a range of azimuthal positions and calculating the mutual information (MI) between the ...
18. Auditory Display
volume. The conference's topics include auditory exploration of data via sonification and audification; real time monitoring of multivariate date; sound in immersive interfaces and teleoperation; perceptual issues in auditory display; sound in generalized computer interfaces; technologies supporting...
19. The mode of synaptic activation of pyramidal neurons in the cat primary somatosensory cortex: an intracellular HRP study.
Yamamoto, T; Samejima, A; Oka, H
1990-01-01
A total of 141 pyramidal neurons in the cat primary somatosensory cortex (SI) were recorded intracellularly under Nembutal anesthesia (7 in layer II, 43 in layer III, 8 in layer IV, 58 in layer V and 25 in layer VI). Most neurons were identified by intracellular staining with HRP, though some layer V pyramidal neurons were identified only electrophysiologically with antidromic activation of medullary pyramid (PT) or pontine nuclear (PN) stimulation. Excitatory synaptic potentials (EPSPs) were analyzed with stimulation of the superficial radial nerve (SR), the ventral posterolateral nucleus (VPL) in the thalamus and the thalamic radiation (WM). The pyramidal neurons in layers III and IV received EPSPs at the shortest latency: 9.1 +/- 2.1 ms (Mean +/- S.D.) for SR and 1.6 +/- 0.7 ms for VPL stimulation. Layer II pyramidal neurons also responded at a short latency to VPL stimulation (1.7 +/- 0.5 ms), though their mean latencies for SR-induced EPSPs were relatively longer (10.6 +/- 1.9 ms). The mean latencies were much longer in layers V and VI pyramidal neurons (10.2 +/- 2.4 ms and 2.9 +/- 1.5 ms in layer V pyramidal neurons and 9.9 +/- 2.5 ms and 2.8 +/- 1.6 ms in layer VI pyramidal ones, respectively for SR and VPL stimulation). The comparison of the latencies between VPL and WM stimulation indicates that most layer III-IV pyramidal neurons and some pyramidal cells in layers II, V and VI received monosynaptic inputs from VPL. These findings are consistent with morphological data on the laminar distribution of thalamocortical fibers, i.e., thalamocortical fibers terminate mainly in the deeper part of layers III and IV with some collaterals in layers V, VI and II-I. The time-sequences of the latencies of VPL-EPSPs indicate that corticocortical and/or transcallosal neurons (pyramidal neurons in layers II and III) fire first and are followed by firing of the output neurons projecting to the subcortical structures (pyramidal neurons in layers V and VI). PMID:2358022
20. [Changes in the intensity of integral afferent inflow from limb receptors and the level of polarization of primary afferent endings in the decerebrate cat during scratching].
Baev, K V; Esipenko, V B
1988-01-01
The experiments performed on decerebrated cats have shown that afferent activity during scratching consisted of two components--tonic and periodic phasic ones. The first component was determined by the limb position, the second was closely related to the amplitude and velocity of joint angle changes. Maximum of integral afferent activity in the cycle coincided with the scratching jerk phase. These two components of afferent activity evoked corresponding depolarization changes in primary afferent terminals and these changes added to those elicited by central generator. Statistical correlations between the aforementioned parameters were studied. The afferent control mechanisms of scratching generator are under discussion. PMID:3380211
1. Auditory agnosia.
Slevc, L Robert; Shell, Alison R
2015-01-01
Auditory agnosia refers to impairments in sound perception and identification despite intact hearing, cognitive functioning, and language abilities (reading, writing, and speaking). Auditory agnosia can be general, affecting all types of sound perception, or can be (relatively) specific to a particular domain. Verbal auditory agnosia (also known as (pure) word deafness) refers to deficits specific to speech processing, environmental sound agnosia refers to difficulties confined to non-speech environmental sounds, and amusia refers to deficits confined to music. These deficits can be apperceptive, affecting basic perceptual processes, or associative, affecting the relation of a perceived auditory object to its meaning. This chapter discusses what is known about the behavioral symptoms and lesion correlates of these different types of auditory agnosia (focusing especially on verbal auditory agnosia), evidence for the role of a rapid temporal processing deficit in some aspects of auditory agnosia, and the few attempts to treat the perceptual deficits associated with auditory agnosia. A clear picture of auditory agnosia has been slow to emerge, hampered by the considerable heterogeneity in behavioral deficits, associated brain damage, and variable assessments across cases. Despite this lack of clarity, these striking deficits in complex sound processing continue to inform our understanding of auditory perception and cognition. PMID:25726291
2. Cat Ownership Perception and Caretaking Explored in an Internet Survey of People Associated with Cats.
Sarah Zito
Full Text Available People who feed cats that they do not perceive they own (sometimes called semi-owners are thought to make a considerable contribution to unwanted cat numbers because the cats they support are generally not sterilized. Understanding people's perception of cat ownership and the psychology underlying cat semi-ownership could inform approaches to mitigate the negative effects of cat semi-ownership. The primary aims of this study were to investigate cat ownership perception and to examine its association with human-cat interactions and caretaking behaviours. A secondary aim was to evaluate a definition of cat semi-ownership (including an association time of ≥1 month and frequent feeding, revised from a previous definition proposed in the literature to distinguish cat semi-ownership from casual interactions with unowned cats. Cat owners and semi-owners displayed similar types of interactions and caretaking behaviours. Nevertheless, caretaking behaviours were more commonly displayed towards owned cats than semi-owned cats, and semi-owned cats were more likely to have produced kittens (p<0.01. All interactions and caretaking behaviours were more likely to be displayed towards cats in semi-ownership relationships compared to casual interaction relationships. Determinants of cat ownership perception were identified (p<0.05 and included association time, attachment, perceived cat friendliness and health, and feelings about unowned cats, including the acceptability of feeding unowned cats. Encouraging semi-owners to have the cats they care for sterilized may assist in reducing the number of unwanted kittens and could be a valuable alternative to trying to prevent semi-ownership entirely. Highly accessible semi-owner "gatekeepers" could help to deliver education messages and facilitate the provision of cat sterilization services to semi-owners. This research enabled semi-ownership to be distinguished from casual interaction relationships and can assist
3. Morphological properties of nociceptive and non-nociceptive neurons in primary somatic cerebral cortex (SI) of cat
2000-01-01
With the techniques of intracellular recording and labelling, we investigated pain sensation and modulation of the somatic cortical cortex at the neuron's level. After observing the evoked potentials from stimulating the saphenous nerves (SN) of 654 neurons in SI area of the cats, we labelled 30 of the neurons with Neurobiotin to preserve the distribution and the morphologic characteristics of the neurons in the cortex. Based on the tridimensional reconstruction in addition to the eletrophysiological functions, we found clear morphological distinctions between nociceptive and non-nociceptive neurons (P＜0.01). This result provided new experimental material to illustrate the function of nociceptive neurons in somatosensory cortex (SI) and presented further evidence to support the "specificity theory" of pain sensation in terms of morphology.
4. Middle components of the auditory evoked response in bilateral temporal lobe lesions. Report on a patient with auditory agnosia
Parving, A; Salomon, G; Elberling, Claus;
1980-01-01
An investigation of the middle components of the auditory evoked response (10--50 msec post-stimulus) in a patient with auditory agnosia is reported. Bilateral temporal lobe infarctions were proved by means of brain scintigraphy, CAT scanning, and regional cerebral blood flow measurements. The mi...
5. Minimal impairment in a rat model of duration discrimination following excitotoxic lesions of primary auditory and prefrontal cortices
2011-09-01
Full Text Available We present a behavioral paradigm for the study of duration perception in the rat, and report the result of neurotoxic lesions that have the goal of identifying sites that mediate duration perception. Using a two-alternative forced-choice paradigm, rats were either trained to discriminate durations of pure tones (range=[200,500]ms; boundary=316ms; Weber fraction after training=0.24+/-0.04, or were trained to discriminate frequencies of pure tones (range=[8,16]kHz; boundary=11.3kHz; Weber=0.16+/-0.11; the latter task is a control for non-timing-specific aspects of the former. Both groups discriminate the same class of sensory stimuli, use the same motions to indicate decisions, have identical trial structures, and are trained to psychophysical threshold; the tasks are thus matched in a number of sensorimotor and cognitive demands. We made neurotoxic lesions of candidate timing-perception areas in the cerebral cortex of both groups. Following extensive bilateral lesions of the auditory cortex, the performance of the frequency-discrimination group was significantly more impaired than that of the duration-discrimination group. We also found that extensive bilateral lesions of the medial prefrontal cortex resulted in little to no impairment of both groups. The behavioral framework presented here provides an audition-based approach to study the neural mechanisms of time estimation and memory for durations.
6. Auditory Neuropathy
... field differ in their opinions about the potential benefits of hearing aids, cochlear implants, and other technologies for people with auditory neuropathy. Some professionals report that hearing aids and personal listening devices such as frequency modulation (FM) systems are ...
7. Cat Ownership Perception and Caretaking Explored in an Internet Survey of People Associated with Cats.
Zito, Sarah; Vankan, Dianne; Bennett, Pauleen; Paterson, Mandy; Phillips, Clive J C
2015-01-01
People who feed cats that they do not perceive they own (sometimes called semi-owners) are thought to make a considerable contribution to unwanted cat numbers because the cats they support are generally not sterilized. Understanding people's perception of cat ownership and the psychology underlying cat semi-ownership could inform approaches to mitigate the negative effects of cat semi-ownership. The primary aims of this study were to investigate cat ownership perception and to examine its association with human-cat interactions and caretaking behaviours. A secondary aim was to evaluate a definition of cat semi-ownership (including an association time of ≥1 month and frequent feeding), revised from a previous definition proposed in the literature to distinguish cat semi-ownership from casual interactions with unowned cats. Cat owners and semi-owners displayed similar types of interactions and caretaking behaviours. Nevertheless, caretaking behaviours were more commonly displayed towards owned cats than semi-owned cats, and semi-owned cats were more likely to have produced kittens (pcats in semi-ownership relationships compared to casual interaction relationships. Determinants of cat ownership perception were identified (pcat friendliness and health, and feelings about unowned cats, including the acceptability of feeding unowned cats. Encouraging semi-owners to have the cats they care for sterilized may assist in reducing the number of unwanted kittens and could be a valuable alternative to trying to prevent semi-ownership entirely. Highly accessible semi-owner "gatekeepers" could help to deliver education messages and facilitate the provision of cat sterilization services to semi-owners. This research enabled semi-ownership to be distinguished from casual interaction relationships and can assist welfare and government agencies to identify cat semi-owners in order to develop strategies to address this source of unwanted cats. PMID:26218243
8. Role of Auditory Non-Verbal Working Memory in Sentence Repetition for Bilingual Children with Primary Language Impairment
Ebert, Kerry Danahy
2014-01-01
Background: Sentence repetition performance is attracting increasing interest as a valuable clinical marker for primary (or specific) language impairment (LI) in both monolingual and bilingual populations. Multiple aspects of memory appear to contribute to sentence repetition performance, but non-verbal memory has not yet been considered. Aims: To…
9. Cat Scan
2004-01-01
<正> A man takes his motionless dog to the vet."Doc,I think my dog is dead.”The vet looks the dog over, goes into a backroom,and comes out with a cat.He places the caton the table next to the dog.The cat walks aroundand sniffs at the dog.The dog does not move.The
10. Effects of parietal TMS on visual and auditory processing at the primary cortical level -- a concurrent TMS-fMRI study
Leitão, Joana; Thielscher, Axel; Werner, Sebastian; Pohmann, Rolf; Noppeney, Uta
2013-01-01
inputs (and vice versa). This concurrent transcranial magnetic stimulation-functional magnetic resonance imaging (TMS-fMRI) study applied repetitive TMS trains at no, low, and high intensity over right intraparietal sulcus (IPS) and vertex to investigate top-down influences on visual and auditory...... cortices under 3 sensory contexts: visual, auditory, and no stimulation. IPS-TMS increased activations in auditory cortices irrespective of sensory context as a result of direct and nonspecific auditory TMS side effects. In contrast, IPS-TMS modulated activations in the visual cortex in a state......-dependent fashion: it deactivated the visual cortex under no and auditory stimulation but amplified the BOLD response to visual stimulation. However, only the response amplification to visual stimulation was selective for IPS-TMS, while the deactivations observed for IPS- and Vertex-TMS resulted from crossmodal...
11. Multi-frequency auditory stimulation disrupts spindling activity in anesthetized animals.
Britvina, T; Eggermont, J J
2008-02-01
It is often implied that during the occurrence of spindle oscillations, thalamocortical neurons do not respond to signals from the outside world. Since recording of sound-evoked activity from cat auditory cortex is common during spindling this implies that sound stimulation changes the spindle-related brain state. Local field potentials and multi-unit activity recorded from cat primary auditory cortex under ketamine anesthesia during successive silence-stimulus-silence conditions were used to investigate the effect of sound on cortical spindle oscillations. Multi-frequency stimulation suppresses spindle waves, as shown by the decrease of spectral power within the spindle frequency range during stimulation as compared with the previous silent period. We show that the percentage suppression is independent of the power of the spindle waves during silence, and that the suppression of spindle power occurs very fast after stimulus onset. The global inter-spindle rhythm was not disturbed during stimulation. Spectrotemporal and correlation analysis revealed that beta waves (15-26 Hz), and to a lesser extent delta waves, were modulated by the same inter-spindle rhythm as spindle oscillations. The suppression of spindle power during stimulation had no effect on the spatial correlation of spindle waves. Firing rates increased under stimulation and spectro-temporal receptive fields could reliably be obtained. The possible mechanism of suppression of spindle waves is discussed and it is suggested that suppression likely occurs through activity of the specific auditory pathway. PMID:18164553
12. Cat scratch disease (image)
Cat scratch disease is an infectious illness associated with cat scratches, bites, or exposure to cat saliva, causing chronic swelling of the lymph nodes. Cat scratch disease is possibly the most common cause of ...
13. HEMANGIOMA HEPÁTICO PRIMÁRIO EM GATA PERSA COM DOENÇA RENAL POLICÍSTICA PRIMARY HEPATIC HEMANGIOMA IN PERSIAN CAT WITH POLYCYSTIC KIDNEY DISEASE
Valdemiro Amaro da Silva Júnior
2008-07-01
great possibility of the rupture, hipovolemic shock and death. Because of its rarity in felines, the aim of case report was describes a primary hepatic hemangioma in a female Persian cat aged ten which the clinical symptoms initially observed were: abdominal volume increase, intermittent vomiting, apathy, anorexia and irregular ruts. Radiographic exam revealed the presence of radiopaque tissues in the liver. The hepatic ultrasound exhibited irregular shape, heterogeneous and hyperechogenic parenchyma, presenting hollowed areas which suggests neoplasm and cysts. Macroscopically it was observed ascite, hepatic steatosis and a neoplastic mass measuring about 12 x 8 cm, in addition to a considerable number of cysts. Polycystic kidneys and ovaries and cystic endometrial hyperplasia were also noticed. Microscopically was diagnosed in the liver: cysts limited by endothelial cells and delicate capsule of connective tissue, steatosis and periportal mononuclear linfocitary hepatitis with biliar ducts proliferation. The tumoral mass rose from the hepatic capsule of the conjunctive tissue. It was characterized by vascular sprouts originated from the endothelial cells with anastomosis and vessels expansion begin on superficial areas. Primary hepatic hemangioma cavernous/capillary was diagnosed. PD was diagnosed in ovarian, uterine and renal tissue.
KEY WORDS: Cat, liver, vascular tumor.
14. Cat's Claw
... R S T U V W X Y Z Cat's Claw Share: On This Page Introduction What the ... More Information Key References © Steven Foster Common Names: cat’s claw, uña de gato Latin Name: Uncaria tomentosa, ...
15. Seizures and epilepsy in cats
Moore SA
2014-01-01
Sarah A Moore Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH, USA Abstract: Seizures are a common presenting complaint in cats, although causes and options for the treatment of seizures in this species have been historically poorly described in the veterinary literature. Seizure manifestation in cats may be different than what is typically seen in dogs, but the underlying causes of seizure activity are the same. These include primary epilepsies, structura...
16. A Catalogue of Anatomical Fugitive Sheets: Cat. 49-62
1999-01-01
Images Cat. 50 Cat. 51 Cat. 53 Cat. 54 Cat. 55 (a) Cat. 55 (b) Cat. 56 Cat. 57: 1 Cat. 57: 2 Cat. 57: 3 Cat. 57: 4 Cat. 59: 1 Cat. 59: 2 Cat. 59: 3 Cat. 59: 4 Cat. 60 Cat. 61 Cat. 62: 1 (a) Cat. 62: 1 (b) Cat. 62: 2 (a) Cat. 62: 2 (b)
17. A Catalogue of Anatomical Fugitive Sheets: Cat. 26-48
1999-01-01
Images Cat. 26: 1 (a) Cat. 26: 1 (b) Cat. 26: 2 (a) Cat. 26: 2(b) Cat. 27: 1 (a) Cat. 27: 1 (b) Cat. 27: 2 (a) Cat. 27: 2 (b) Cat. 28 Cat. 29: 2 (a) Cat. 29: 2 (b) Cat. 30: 1 Cat. 30: 2 Cat. 30: 3 Cat. 33 Cat. 34: 1 Cat. 34: 2 Cat. 35: 1 Cat. 35: 2 Cat. 35: 3 Cat. 36 Cat. 37 Cat. 38: 1 Cat. 38: 2 Cat. 40 Cat. 42 Cat. 43 Cat. 44 Cat. 45: 1 Cat. 45: 2 Cat. 46 Cat. 47: 1 Cat. 47: 2 Cat. 47: 3 Cat. 48: 1 Cat. 48: 2 Cat. 48: 3
18. Loudness perception in the domestic cat: reaction time estimates of equal loudness contours and recruitment effects.
May, Bradford J; Little, Nicole; Saylor, Stephanie
2009-06-01
The domestic cat is the primary physiological model of loudness coding and recruitment. At present, there are no published descriptions of loudness perception in this species. This study used a reaction time task to characterize loudness perception in six behaviorally trained cats. The psychophysical approach was based on the assumption that sounds of equal loudness elicit responses of equal latency. The resulting equal latency contours reproduced well-known features of human equal loudness contours. At the completion of normal baseline measures, the cats were exposed to intense sound to investigate the behavioral correlates of loudness recruitment, the abnormally rapid growth of loudness that is commonly associated with hearing loss. Observed recruitment effects were similar in magnitude to those that have been reported in hearing-impaired humans. Linear hearing aid amplification is known to improve speech intelligibility but also exacerbate recruitment in impaired listeners. The effects of speech spectra and amplification on recruitment were explored by measuring the growth of loudness for natural and amplified vowels before and after sound exposure. Vowels produced more recruitment than tones, and the effect was exacerbated by the selective amplification of formant structure. These findings support the adequacy of the domestic cat as a model system for future investigations of the auditory processes that underlie loudness perception, recruitment, and hearing aid design. PMID:19198944
19. Management of hypertension in a geriatric cat
Thompson, Jennifer
2004-01-01
Hyperthyroidism and chronic renal disease occur commonly in geriatric cats, often in association with potentially life-threatening primary or secondary hypertension. Early treatment of hypertension minimizes damage to vital organs. This case illustrates the complexity of managing hypertension in a geriatric cat with both hyperthyroidism and renal disease.
20. Schroedinger's cat
The issue is to seek quantum interference effects in an arbitrary field, in particular in psychology. For this a digest of quantum mechanics over finite-n-dimensional Hilbert space is invented. In order to match crude data not only von Neumann's mixed states are used but also a parallel notion of unsharp tests. The mathematically styled text (and earlier work on multibin tests, designated MB) deals largely with these new tests. Quantum psychology itself is only given a foundation. It readily engenders objections; its plausibility is developed gradually, in interlocking essays. There is also the empirically definite proposal that (state, test, outcome)-indexed counts be gathered to record data, then fed to a 'matrix format' (MF) search for quantum models. A previously proposed experiment in visual perception which has since failed to find significant quantum correlations, is discussed. The suspicion that quantum mechanics is all around goes beyond MF, and 'Schroedinger's cat' symbolizes this broader perspective. (author)
1. Cat and Dog Bites
MENU Return to Web version Cat and Dog Bites Cat and Dog Bites How should I take care of a bite from a cat or a dog? Whether from a family pet or a neighborhood stray, cat and dog bites are common. Here are some things you ...
2. Activity changes of the cat paraventricular hypothalamus during stressor exposure
Kristensen, Morten Pilgaard; Rector, David M; Poe, Gina R;
2004-01-01
Dorso-medial paraventricular hypothalamus (PVH) activity was assessed by light scattering procedures in freely behaving cats during auditory stressor exposure. Acoustic noise (> 95dB) raised plasma ACTH concentrations, somatic muscle tonus, respiratory frequency and cardiac rates; PVH activity...
3. Frequency band-importance functions for auditory and auditory-visual speech recognition
Grant, Ken W.
2005-04-01
In many everyday listening environments, speech communication involves the integration of both acoustic and visual speech cues. This is especially true in noisy and reverberant environments where the speech signal is highly degraded, or when the listener has a hearing impairment. Understanding the mechanisms involved in auditory-visual integration is a primary interest of this work. Of particular interest is whether listeners are able to allocate their attention to various frequency regions of the speech signal differently under auditory-visual conditions and auditory-alone conditions. For auditory speech recognition, the most important frequency regions tend to be around 1500-3000 Hz, corresponding roughly to important acoustic cues for place of articulation. The purpose of this study is to determine the most important frequency region under auditory-visual speech conditions. Frequency band-importance functions for auditory and auditory-visual conditions were obtained by having subjects identify speech tokens under conditions where the speech-to-noise ratio of different parts of the speech spectrum is independently and randomly varied on every trial. Point biserial correlations were computed for each separate spectral region and the normalized correlations are interpreted as weights indicating the importance of each region. Relations among frequency-importance functions for auditory and auditory-visual conditions will be discussed.
4. Auditory Cortex Basal Activity Modulates Cochlear Responses in Chinchillas
León, Alex; Elgueda, Diego; Silva, María A.; Hamamé, Carlos M.; Delano, Paul H.
2012-01-01
Background The auditory efferent system has unique neuroanatomical pathways that connect the cerebral cortex with sensory receptor cells. Pyramidal neurons located in layers V and VI of the primary auditory cortex constitute descending projections to the thalamus, inferior colliculus, and even directly to the superior olivary complex and to the cochlear nucleus. Efferent pathways are connected to the cochlear receptor by the olivocochlear system, which innervates outer hair cells and auditory...
5. Cat Scratch Disease
Cat scratch disease (CSD) is an illness caused by the bacterium Bartonella henselae. Almost half of all cats carry the infection ... symptoms of CSD, call your doctor. Centers for Disease Control and Prevention
6. Cat Scratch Disease
Cat scratch disease (CSD) is an illness caused by the bacterium Bartonella henselae. Almost half of all cats carry the infection at some ... Poor appetite For people with weak immune systems, CSD may cause more serious problems. The best way ...
7. Visual discrimination learning under switching procedure in visually deprived cats.
Zernicki, B
1999-04-01
Previous studies have shown that fine visual discrimination learning is severely impaired in cats binocularly deprived in the early period of life (BD cats) and also somewhat in control cats reared with open eyes in the limited laboratory environment (C cats) compared with cats reared in a normal rural environment (N cats). It was concluded that visual deprivation impairs perceptual learning. In the present study discriminative stimuli were dissimilar and so the task was perceptually easy, but using a switching procedure made it associatively difficult. In regular trials a gate with a grating pattern was positive and a blank gate negative, whereas in switching trials the meaning of the gates was reversed. The switching stimulus was intermittent light in some stages of training and intermittent tone in others. Learning was severely impaired in BD cats and somewhat in C cats and the deficit was similar under visual and auditory switching. Thus, early visual deprivation impairs associative learning. The impairment probably includes associations between switching stimulus and instrumental responses and configural associations between switching stimulus and discriminative stimuli. PMID:10212071
8. Getting a CAT Scan
Full Text Available ... Snowboarding, Skating Crushes What's a Booger? Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A A Text Size en español Obtención de una tomografía computada (video) CAT stands for "computerized axial tomography." Translated, that means ...
9. Getting a CAT Scan
Full Text Available ... Here's Help White House Lunch Recipes Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A A Text Size en español Obtención de una tomografía computada (video) CAT stands for "computerized axial tomography." Translated, that means ...
10. Getting a CAT Scan
Full Text Available ... Crushes What's a Booger? Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A A Text Size en español Obtención de una tomografía computada (video) CAT stands for "computerized axial tomography." Translated, that ...
11. Auditory imagery: empirical findings.
Hubbard, Timothy L
2010-03-01
The empirical literature on auditory imagery is reviewed. Data on (a) imagery for auditory features (pitch, timbre, loudness), (b) imagery for complex nonverbal auditory stimuli (musical contour, melody, harmony, tempo, notational audiation, environmental sounds), (c) imagery for verbal stimuli (speech, text, in dreams, interior monologue), (d) auditory imagery's relationship to perception and memory (detection, encoding, recall, mnemonic properties, phonological loop), and (e) individual differences in auditory imagery (in vividness, musical ability and experience, synesthesia, musical hallucinosis, schizophrenia, amusia) are considered. It is concluded that auditory imagery (a) preserves many structural and temporal properties of auditory stimuli, (b) can facilitate auditory discrimination but interfere with auditory detection, (c) involves many of the same brain areas as auditory perception, (d) is often but not necessarily influenced by subvocalization, (e) involves semantically interpreted information and expectancies, (f) involves depictive components and descriptive components, (g) can function as a mnemonic but is distinct from rehearsal, and (h) is related to musical ability and experience (although the mechanisms of that relationship are not clear). PMID:20192565
12. Pulmonary thromboembolism in cats.
Schermerhorn, Thomas; Pembleton-Corbett, Julie R; Kornreich, Bruce
2004-01-01
Pulmonary thromboembolism (PTE) is rarely diagnosed in cats, and the clinical features of the disease are not well known. PTE was diagnosed at postmortem examination in 17 cats, a prevalence of 0.06% over a 24-year period. The age of affected cats ranged from 10 months to 18 years, although young (10 years) cats were more commonly affected than were middle-aged cats. Males and females were equally affected. The majority of cats with PTE (n = 16) had concurrent disease, which was often severe. The most common diseases identified in association with PTE were neoplasia, anemia of unidentified cause, and pancreatitis. Cats with glomerulonephritis, encephalitis, pneumonia, heart disease, and hepatic lipidosis were also represented in this study. Most cats with PTE demonstrated dyspnea and respiratory distress before death or euthanasia, but PTE was not recognized ante mortem in any cat studied. In conclusion, PTE can affect cats of any age and is associated with a variety of systemic and inflammatory disorders. It is recommended that the same clinical criteria used to increase the suspicion of PTE in dogs should also be applied to cats. PMID:15320593
13. A Catalogue of Anatomical Fugitive Sheets: Cat. 1-10
1999-01-01
Images Cat. 1 Cat. 2 (a) Cat. 2 (b) Cat. 2 (c) Cat. 2 (d) Cat. 2 (e) Cat. 2 (f) Cat. 3: 1 (a) Cat. 3: 1 (b) Cat. 3: 2 (a) Cat. 3: 2 (b) Cat. 4: 1 Cat. 4: 2 Cat. 6: 1 (a) Cat. 6: 1 (b) Cat. 6: 2 (a) Cat. 6: 2 (b) Cat. 7: 1 (a) Cat. 7: 1 (b) Cat. 7: 2 (a) Cat. 7: 2 (b) Cat. 8: 1 Cat. 9: 1 Cat. 9: 2 Cat. 10: 1 Cat. 10: 2
14. Network and external perturbation induce burst synchronisation in cat cerebral cortex
Lameu, Ewandson L.; Borges, Fernando S.; Borges, Rafael R.; Batista, Antonio M.; Baptista, Murilo S.; Viana, Ricardo L.
2016-05-01
The brain of mammals are divided into different cortical areas that are anatomically connected forming larger networks which perform cognitive tasks. The cat cerebral cortex is composed of 65 areas organised into the visual, auditory, somatosensory-motor and frontolimbic cognitive regions. We have built a network of networks, in which networks are connected among themselves according to the connections observed in the cat cortical areas aiming to study how inputs drive the synchronous behaviour in this cat brain-like network. We show that without external perturbations it is possible to observe high level of bursting synchronisation between neurons within almost all areas, except for the auditory area. Bursting synchronisation appears between neurons in the auditory region when an external perturbation is applied in another cognitive area. This is a clear evidence that burst synchronisation and collective behaviour in the brain might be a process mediated by other brain areas under stimulation.
15. Fine functional organization of auditory cortex revealed by Fourier optical imaging
Kalatsky, Valery A.; Polley, Daniel B.; Merzenich, Michael M.; Schreiner, Christoph E.; Stryker, Michael P.
2005-01-01
We provide an overall view of the functional tonotopic organization of the auditory cortex in the rat. We apply a recently developed technique for acquiring intrinsic signal optical maps, Fourier imaging, in the rat auditory cortex. These highly detailed maps, derived in a several-minute-long recording procedure, delineate multiple auditory cortical areas and demonstrate their shapes, sizes, and tonotopic order. Beyond the primary auditory cortex, there are at least three distinct areas with ...
16. A Catalogue of Anatomical Fugitive Sheets: Cat. 11-25
1999-01-01
Images Cat. 11 (a) Cat. 11 (b) Cat. 11 (c) Cat. 11 (d) Cat. 12: 1 (a) Cat. 12: 1 (b) Cat. 12: 2 (a) Cat. 12: 2 (b) Cat. 13 Cat. 14 (a) Cat. 14 (b) Cat. 14 (c) Cat. 15 (a) Cat. 15 (b) Cat. 17: 1 Cat. 17: 2 Cat. 18: 1 Cat. 18: 2 Cat. 19: 1 (a) Cat. 19: 1 (b) Cat. 19: 2 (a) Cat. 19: 2 (b) Cat. 20: 1 Cat. 20: 2 (a) Cat. 20: 2 (b) Cat. 21 (a) Cat. 21 (b) Cat. 21 (c) Cat. 21 (d) Cat. 21 (e) Cat. 22 Cat. 24: 1 and 2 Cat. 25: 1 Cat. 25: 2 Cat. 25: 3 Cat. 25: 4
17. A tortoiseshell male cat
Pedersen, A. S.; Berg, Lise Charlotte; Almstrup, Kristian;
2014-01-01
Tortoiseshell coat color is normally restricted to female cats due to X-linkage of the gene that encodes the orange coat color. Tortoiseshell male cats do, however, occur at a low frequency among tortoiseshell cats because of chromosome aberrations similar to the Klinefelter syndrome in man...... tissue from a tortoiseshell male cat referred to us. Chromosome analysis using RBA-banding consistently revealed a 39,XXY karyotype. Histological examinations of testis biopsies from this cat showed degeneration of the tubules, hyperplasia of the interstitial tissue, and complete loss of germ cells....... Immunostaining using anti-vimentin and anti-VASA (DDX4) showed that only Sertoli cells and no germ cells were observed in the testicular tubules. As no sign of spermatogenesis was detected, we conclude that this is a classic case of a sterile, male tortoiseshell cat with a 39,XXY chromosome complement. © 2013 S...
18. Auditory-motor learning influences auditory memory for music.
Brown, Rachel M; Palmer, Caroline
2012-05-01
In two experiments, we investigated how auditory-motor learning influences performers' memory for music. Skilled pianists learned novel melodies in four conditions: auditory only (listening), motor only (performing without sound), strongly coupled auditory-motor (normal performance), and weakly coupled auditory-motor (performing along with auditory recordings). Pianists' recognition of the learned melodies was better following auditory-only or auditory-motor (weakly coupled and strongly coupled) learning than following motor-only learning, and better following strongly coupled auditory-motor learning than following auditory-only learning. Auditory and motor imagery abilities modulated the learning effects: Pianists with high auditory imagery scores had better recognition following motor-only learning, suggesting that auditory imagery compensated for missing auditory feedback at the learning stage. Experiment 2 replicated the findings of Experiment 1 with melodies that contained greater variation in acoustic features. Melodies that were slower and less variable in tempo and intensity were remembered better following weakly coupled auditory-motor learning. These findings suggest that motor learning can aid performers' auditory recognition of music beyond auditory learning alone, and that motor learning is influenced by individual abilities in mental imagery and by variation in acoustic features. PMID:22271265
19. Narrow, duplicated internal auditory canal
Ferreira, T. [Servico de Neurorradiologia, Hospital Garcia de Orta, Avenida Torrado da Silva, 2801-951, Almada (Portugal); Shayestehfar, B. [Department of Radiology, UCLA Oliveview School of Medicine, Los Angeles, California (United States); Lufkin, R. [Department of Radiology, UCLA School of Medicine, Los Angeles, California (United States)
2003-05-01
A narrow internal auditory canal (IAC) constitutes a relative contraindication to cochlear implantation because it is associated with aplasia or hypoplasia of the vestibulocochlear nerve or its cochlear branch. We report an unusual case of a narrow, duplicated IAC, divided by a bony septum into a superior relatively large portion and an inferior stenotic portion, in which we could identify only the facial nerve. This case adds support to the association between a narrow IAC and aplasia or hypoplasia of the vestibulocochlear nerve. The normal facial nerve argues against the hypothesis that the narrow IAC is the result of a primary bony defect which inhibits the growth of the vestibulocochlear nerve. (orig.)
20. Altered Cross-Modal Processing in the Primary Auditory Cortex of Congenitally Deaf Adults: A Visual-Somatosensory fMRI Study with a Double-Flash Illusion
Karns, Christina M.; Dow, Mark W.; Neville, Helen J.
2012-01-01
The developing brain responds to the environment by using statistical correlations in input to guide functional and structural changes—that is, the brain displays neuroplasticity. Experience shapes brain development throughout life, but neuroplasticity is variable from one brain system to another. How does the early loss of a sensory modality affect this complex process? We examined cross-modal neuroplasticity in anatomically defined subregions of Heschl's gyrus, the site of human primary aud...
1. That Fat Cat
Lambert, Phyllis Gilchrist
2012-01-01
This activity began with a picture book, Nurit Karlin's "Fat Cat On a Mat" (HarperCollins; 1998). The author and her students started their project with a 5-inch circular template for the head of their cats. They reviewed shapes as they drew the head and then added the ears and nose, which were triangles. Details to the face were added when…
2. Getting a CAT Scan
Full Text Available ... Dictionary of Medical Words En Español What Other Kids Are Reading Movie: Digestive System Winter Sports: Sledding, ... Booger? Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A ...
3. Getting a CAT Scan
Full Text Available ... Skiing, Snowboarding, Skating Crushes What's a Booger? Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A A Text Size en español Obtención de ...
4. Auditory Integration Training
Zahra Jafari
2002-07-01
Full Text Available Auditory integration training (AIT is a hearing enhancement training process for sensory input anomalies found in individuals with autism, attention deficit hyperactive disorder, dyslexia, hyperactivity, learning disability, language impairments, pervasive developmental disorder, central auditory processing disorder, attention deficit disorder, depressin, and hyperacute hearing. AIT, recently introduced in the United States, and has received much notice of late following the release of The Sound of a Moracle, by Annabel Stehli. In her book, Mrs. Stehli describes before and after auditory integration training experiences with her daughter, who was diagnosed at age four as having autism.
5. 小鼠初级听皮质神经元的强度调谐特性与机制分析%Intensity Tuning of Neurons in The Primary Auditory Cortex of Albino Mouse
齐巧珍; 佀文娟; 罗峰; 王欣
2013-01-01
强度是声音的基本参数之一,听神经元的强度调谐在听觉信息处理方面具有重要意义.以往研究发现γ-氨基丁酸(γ-aminobutyric acid,GABA)能抑制性输入在强度调谐的形成过程中起重要作用,但对抑制性输入与局部神经回路之间的关系并不清楚.本实验通过在体细胞外电生理记录和神经药理学方法,分析了小鼠初级听皮质神经元的强度调谐特性,结果显示:单调型神经元在声刺激强度自中等强度增高时潜伏期缩短(P＜0.05)且发放持续时间延长(P＜0.05),非单调型神经元在声刺激强度自最佳强度增高时潜伏期不变且发放持续时间缩短(P＜0.01).注射GABA能阻断剂荷包牡丹碱(bicuculline,Bic)后,39.3％的神经元强度调谐类型不变,42.9％的神经元非单调性减弱,17.9％的神经元非单调性增强.表明GABA能抑制并非是形成非单调性的唯一因素,兴奋性输入本身的非单调性和高阈值非GABA能抑制的激活也可能在其中发挥作用.推测由兴奋性和抑制性输入所构成的局部神经功能回路及其整合决定了听皮质神经元的强度调谐特性.%Cortical neurons that are tuned to sound intensity (non-monotonic neurons) are very important for processing auditory information. Considering the fact that all auditory nerve fibers have monotonical responses, inhibition in the primary auditory cortex (AI) is essential for intensity tuning. By using free field sound stimulation and in vivo extracellular recording, the present study investigated the intensity-tuning properties in AI neurons of mouse (Mus musculus, Km). We also examined the effect of cortical application of the GABAa receptor antagonist bicuculline on AI intensity tuning in order to indentify the possible source of inhibition. The intensity-tuning curves were recorded in 72 AI neurons among which 28 showed monotonic responses and 44 showed non-monotonic responses. In non-monotonic neurons, there was no
This document, prepared in February 1993, addresses the most common questions asked by APS Collaborative Access Teams (CATs). The answers represent the best judgment on the part of the APS at this time. In some cases, details are provided in separate documents to be supplied by the APS. Some of the answers are brief because details are not yet available. The questions are separated into five categories representing different aspects of CAT interactions with the APS: (1) Memorandum of Understanding (MOU), (2) CAT Beamline Review and Construction, (3) CAT Beamline Safety, (4) CAT Beamline Operations, and (5) Miscellaneous. The APS plans to generate similar documents as needed to both address new questions and clarify answers to present questions
7. Overriding auditory attentional capture
Dalton, Polly; Lavie, Nilli
2007-01-01
Attentional capture by color singletons during shape search can be eliminated when the target is not a feature singleton (Bacon & Egeth, 1994). This suggests that a "singleton detection" search strategy must be adopted for attentional capture to occur. Here we find similar effects on auditory attentional capture. Irrelevant high-intensity singletons interfered with an auditory search task when the target itself was also a feature singleton. However, singleton interference was eliminated when ...
8. Computed tomographic aspects of primary brain tumors in dogs and cats; Aspectos tomograficos de tumores cerebrais primarios em caes e gatos
Babicsak, Viviam Rocco; Zardo, Karen Maciel; Santos, Debora Rodrigues dos; Silva, Luciana Carandina da; Machado, Vania Maria de Vasconcelos; Vulcano, Luiz Carlos, E-mail: [email protected] [Setor de Diagnostico por Imagem - FMVZ - UNESP/Botucatu, SP (Brazil)
2011-07-01
Over the years, the Veterinary Medicine has made great advances, enabling thus the diagnosis of many diseases. As a result of this new situation, there was an increased expectation of life of animals resulting in an increase in the number of clinical care of older animals. Thus, diseases considered unusual in the past, begin to be diagnosed more frequently, as is the case of brain damage. Recently, computed tomography has been widely used in Brazil as a tool to aid in the diagnosis of several diseases. This noninvasive imaging technique allows the identification and evaluation of lesions of central nervous tissue such as brain tumors. This provides information about the size, shape and location of the lesion, in addition to the magnitude of compression and invasion of adjacent structures by the tumor and its side effects (such as the peritumoral edema and hydrocephalus). The image obtained from computed tomography may suggest the presence of a certain type brain tumor, data of great importance for the prognosis and treatment of the animal. This review covers the computed tomography aspects of primary brain tumors such as meningiomas, astrocytomas, oligodendrogliomas, choroid plexus tumors and ependymomas. However, despite the computed tomography provide much information about the changes inside the skull; no way replace histopathological examination in determining the definitive diagnosis. (author)
9. [Central auditory prosthesis].
Lenarz, T; Lim, H; Joseph, G; Reuter, G; Lenarz, M
2009-06-01
Deaf patients with severe sensory hearing loss can benefit from a cochlear implant (CI), which stimulates the auditory nerve fibers. However, patients who do not have an intact auditory nerve cannot benefit from a CI. The majority of these patients are neurofibromatosis type 2 (NF2) patients who developed neural deafness due to growth or surgical removal of a bilateral acoustic neuroma. The only current solution is the auditory brainstem implant (ABI), which stimulates the surface of the cochlear nucleus in the brainstem. Although the ABI provides improvement in environmental awareness and lip-reading capabilities, only a few NF2 patients have achieved some limited open set speech perception. In the search for alternative procedures our research group in collaboration with Cochlear Ltd. (Australia) developed a human prototype auditory midbrain implant (AMI), which is designed to electrically stimulate the inferior colliculus (IC). The IC has the potential as a new target for an auditory prosthesis as it provides access to neural projections necessary for speech perception as well as a systematic map of spectral information. In this paper the present status of research and development in the field of central auditory prostheses is presented with respect to technology, surgical technique and hearing results as well as the background concepts of ABI and AMI. PMID:19517084
10. Impact of Educational Level on Performance on Auditory Processing Tests.
Murphy, Cristina F B; Rabelo, Camila M; Silagi, Marcela L; Mansur, Letícia L; Schochat, Eliane
2016-01-01
Research has demonstrated that a higher level of education is associated with better performance on cognitive tests among middle-aged and elderly people. However, the effects of education on auditory processing skills have not yet been evaluated. Previous demonstrations of sensory-cognitive interactions in the aging process indicate the potential importance of this topic. Therefore, the primary purpose of this study was to investigate the performance of middle-aged and elderly people with different levels of formal education on auditory processing tests. A total of 177 adults with no evidence of cognitive, psychological or neurological conditions took part in the research. The participants completed a series of auditory assessments, including dichotic digit, frequency pattern and speech-in-noise tests. A working memory test was also performed to investigate the extent to which auditory processing and cognitive performance were associated. The results demonstrated positive but weak correlations between years of schooling and performance on all of the tests applied. The factor "years of schooling" was also one of the best predictors of frequency pattern and speech-in-noise test performance. Additionally, performance on the working memory, frequency pattern and dichotic digit tests was also correlated, suggesting that the influence of educational level on auditory processing performance might be associated with the cognitive demand of the auditory processing tests rather than auditory sensory aspects itself. Longitudinal research is required to investigate the causal relationship between educational level and auditory processing skills. PMID:27013958
11. Spatial processing in the auditory cortex of the macaque monkey
Recanzone, Gregg H.
2000-10-01
The patterns of cortico-cortical and cortico-thalamic connections of auditory cortical areas in the rhesus monkey have led to the hypothesis that acoustic information is processed in series and in parallel in the primate auditory cortex. Recent physiological experiments in the behaving monkey indicate that the response properties of neurons in different cortical areas are both functionally distinct from each other, which is indicative of parallel processing, and functionally similar to each other, which is indicative of serial processing. Thus, auditory cortical processing may be similar to the serial and parallel "what" and "where" processing by the primate visual cortex. If "where" information is serially processed in the primate auditory cortex, neurons in cortical areas along this pathway should have progressively better spatial tuning properties. This prediction is supported by recent experiments that have shown that neurons in the caudomedial field have better spatial tuning properties than neurons in the primary auditory cortex. Neurons in the caudomedial field are also better than primary auditory cortex neurons at predicting the sound localization ability across different stimulus frequencies and bandwidths in both azimuth and elevation. These data support the hypothesis that the primate auditory cortex processes acoustic information in a serial and parallel manner and suggest that this may be a general cortical mechanism for sensory perception.
12. StreamCat
U.S. Environmental Protection Agency — The StreamCat Dataset provides summaries of natural and anthropogenic landscape features for ~2.65 million streams, and their associated catchments, within the...
13. Haemobartonellosis in Van Cats
AKKAN, Hasan Altan; Karaca, Mehmet; TÜTÜNCÜ, Mehmet
2005-01-01
The present study was conducted to determine prevalence of Haemobartonella felis in Van cats. 121 Van cats (82 female, 39 male, aged 1-9 years) were the materials of the study. To determine biochemical and haematological parameters, 2 ml blood with and without anticoagulant were taken according to technique from vena cephalica antebrachii. H. felis was detected in blood smears preparations of 18 (14.88%) by Papenheim staining. Among biochemical parameters aspartate amino transferase (AST), al...
14. Resolving Schrodinger's cat
Hobson, Art
2016-01-01
Schrodinger's famous cat has long been misunderstood. According to quantum theory and experiments with entangled systems, an entangled state such as the Schrodinger's cat state is neither a superposition of states of either subsystem nor a superposition of compound states of the composite system, but rather a nonlocal superposition of correlations between pairs of states of the two subsystems. The entangled post-measurement state that results from an ideal measurement is not paradoxical, but ...
15. Prospects for Replacement of Auditory Neurons by Stem Cells
Shi, Fuxin; Edge, Albert S. B.
2013-01-01
Sensorineural hearing loss is caused by degeneration of hair cells or auditory neurons. Spiral ganglion cells, the primary afferent neurons of the auditory system, are patterned during development and send out projections to hair cells and to the brainstem under the control of largely unknown guidance molecules. The neurons do not regenerate after loss and even damage to their projections tends to be permanent. The genesis of spiral ganglion neurons and their synapses forms a basis for regene...
16. Overriding auditory attentional capture.
Dalton, Polly; Lavie, Nilli
2007-02-01
Attentional capture by color singletons during shape search can be eliminated when the target is not a feature singleton (Bacon & Egeth, 1994). This suggests that a "singleton detection" search strategy must be adopted for attentional capture to occur. Here we find similar effects on auditory attentional capture. Irrelevant high-intensity singletons interfered with an auditory search task when the target itself was also a feature singleton. However, singleton interference was eliminated when the target was not a singleton (i.e., when nontargets were made heterogeneous, or when more than one target sound was presented). These results suggest that auditory attentional capture depends on the observer's attentional set, as does visual attentional capture. The suggestion that hearing might act as an early warning system that would always be tuned to unexpected unique stimuli must therefore be modified to accommodate these strategy-dependent capture effects. PMID:17557587
17. Auditory and Visual Sensations
Ando, Yoichi
2010-01-01
Professor Yoichi Ando, acoustic architectural designer of the Kirishima International Concert Hall in Japan, presents a comprehensive rational-scientific approach to designing performance spaces. His theory is based on systematic psychoacoustical observations of spatial hearing and listener preferences, whose neuronal correlates are observed in the neurophysiology of the human brain. A correlation-based model of neuronal signal processing in the central auditory system is proposed in which temporal sensations (pitch, timbre, loudness, duration) are represented by an internal autocorrelation representation, and spatial sensations (sound location, size, diffuseness related to envelopment) are represented by an internal interaural crosscorrelation function. Together these two internal central auditory representations account for the basic auditory qualities that are relevant for listening to music and speech in indoor performance spaces. Observed psychological and neurophysiological commonalities between auditor...
18. Resizing Auditory Communities
Kreutzfeldt, Jacob
2012-01-01
Heard through the ears of the Canadian composer and music teacher R. Murray Schafer the ideal auditory community had the shape of a village. Schafer’s work with the World Soundscape Project in the 70s represent an attempt to interpret contemporary environments through musical and auditory...... of sound as an active component in shaping urban environments. As urban conditions spreads globally, new scales, shapes and forms of communities appear and call for new distinctions and models in the study and representation of sonic environments. Particularly so, since urban environments...
19. Effects of multitasking on operator performance using computational and auditory tasks.
Fasanya, Bankole K
2016-09-01
20. Shaping the aging brain: Role of auditory input patterns in the emergence of auditory cortical impairments
Brishna Soraya Kamal
2013-09-01
Full Text Available Age-related impairments in the primary auditory cortex (A1 include poor tuning selectivity, neural desynchronization and degraded responses to low-probability sounds. These changes have been largely attributed to reduced inhibition in the aged brain, and are thought to contribute to substantial hearing impairment in both humans and animals. Since many of these changes can be partially reversed with auditory training, it has been speculated that they might not be purely degenerative, but might rather represent negative plastic adjustments to noisy or distorted auditory signals reaching the brain. To test this hypothesis, we examined the impact of exposing young adult rats to 8 weeks of low-grade broadband noise on several aspects of A1 function and structure. We then characterized the same A1 elements in aging rats for comparison. We found that the impact of noise exposure on A1 tuning selectivity, temporal processing of auditory signal and responses to oddball tones was almost indistinguishable from the effect of natural aging. Moreover, noise exposure resulted in a reduction in the population of parvalbumin inhibitory interneurons and cortical myelin as previously documented in the aged group. Most of these changes reversed after returning the rats to a quiet environment. These results support the hypothesis that age-related changes in A1 have a strong activity-dependent component and indicate that the presence or absence of clear auditory input patterns might be a key factor in sustaining adult A1 function.
1. Postnatal development of the endbulb of Held in congenitally deaf cats
Christa A Baker
2010-05-01
Full Text Available The endbulbs of Held are formed by the ascending branches of myelinated auditory nerve fibers and represent one of the largest synaptic endings in the brain. Normally, these endings are highly branched and each can form up to 1000 dome-shaped synapses. The deaf white cat is a model of congenital deafness involving a type of cochleosaccular degeneration that mimics the Scheibe deformity in humans. Mature deaf white cats exhibit reduced endbulb branching, hypertrophy of postsynaptic densities (PSDs, and changes in synaptic vesicle density. Because cats are essentially deaf at birth, we wanted to determine if the progression of brain abnormalities was linked in time to the failure of normal hearing development. The rationale was that the lack of sound-evoked activity would trigger pathologic change in deaf kittens. The cochleae of deaf cats did not exhibit abnormal morphology at birth. After the first postnatal week, however, the presence of a collapsed scala media signaled the difference between deaf and hearing cats. By working backwards in age, endbulbs of deaf cats expressed flattened and elongated PSDs and increased synaptic vesicle density as compared to normal endbulbs. These differences are present at birth in some white kittens, presaging deafness despite their normal cochlear histology. We speculate that hearing pathology is signaled by a perinatal loss of spontaneous bursting activity in auditory nerve fibers or perhaps by some factor released by hair cell synapses before obliteration of the organ of Corti.
2. Dissociation of Detection and Discrimination of Pure Tones following Bilateral Lesions of Auditory Cortex
Andrew R Dykstra; Christine K Koh; Braida, Louis D.; Tramo, Mark Jude
2012-01-01
It is well known that damage to the peripheral auditory system causes deficits in tone detection as well as pitch and loudness perception across a wide range of frequencies. However, the extent to which to which the auditory cortex plays a critical role in these basic aspects of spectral processing, especially with regard to speech, music, and environmental sound perception, remains unclear. Recent experiments indicate that primary auditory cortex is necessary for the normally-high perceptual...
3. Diffusion tensor imaging of dolphin brains reveals direct auditory pathway to temporal lobe
Berns, Gregory S.; Cook, Peter F.; Foxley, Sean; Jbabdi, Saad; Miller, Karla L.; Marino, Lori
2015-01-01
The brains of odontocetes (toothed whales) look grossly different from their terrestrial relatives. Because of their adaptation to the aquatic environment and their reliance on echolocation, the odontocetes' auditory system is both unique and crucial to their survival. Yet, scant data exist about the functional organization of the cetacean auditory system. A predominant hypothesis is that the primary auditory cortex lies in the suprasylvian gyrus along the vertex of the hemispheres, with this...
4. E-Z-CAT
A new barium sulphate suspension, E-Z-CAT, for use as an oral contrast medium at computed tomography of the abdomen has been compared with the commonly used water-soluble iodinated contrast medium Gastrografin as regards patient tolerance and diagnostic information. The investigation was conducted as an unpaired randomized single-blind study in 100 consecutive patients. E-Z-CAT seems to be preferred because of its better taste, its lesser tendency to cause diarrhoea, and for usage in patients who are known to be hypersensitive to iodinated contrast media. The diagnostic information was the same for both contrast media. (Auth.)
5. An anatomical and functional topography of human auditory cortical areas
Michelle eMoerel
2014-07-01
Full Text Available While advances in magnetic resonance imaging (MRI throughout the last decades have enabled the detailed anatomical and functional inspection of the human brain non-invasively, to date there is no consensus regarding the precise subdivision and topography of the areas forming the human auditory cortex. Here, we propose a topography of the human auditory areas based on insights on the anatomical and functional properties of human auditory areas as revealed by studies of cyto- and myelo-architecture and fMRI investigations at ultra-high magnetic field (7 Tesla. Importantly, we illustrate that - whereas a group-based approach to analyze functional (tonotopic maps is appropriate to highlight the main tonotopic axis - the examination of tonotopic maps at single subject level is required to detail the topography of primary and non-primary areas that may be more variable across subjects. Furthermore, we show that considering multiple maps indicative of anatomical (i.e. myelination as well as of functional properties (e.g. broadness of frequency tuning is helpful in identifying auditory cortical areas in individual human brains. We propose and discuss a topography of areas that is consistent with old and recent anatomical post mortem characterizations of the human auditory cortex and that may serve as a working model for neuroscience studies of auditory functions.
6. ServCat Sensitivity Guidelines
US Fish and Wildlife Service, Department of the Interior — This guide covers sensitivity in ServCat. This document provides technical guidance on how sensitivity fields work in ServCat, and provides suggestions on what...
7. Prospects for replacement of auditory neurons by stem cells.
Shi, Fuxin; Edge, Albert S B
2013-03-01
Sensorineural hearing loss is caused by degeneration of hair cells or auditory neurons. Spiral ganglion cells, the primary afferent neurons of the auditory system, are patterned during development and send out projections to hair cells and to the brainstem under the control of largely unknown guidance molecules. The neurons do not regenerate after loss and even damage to their projections tends to be permanent. The genesis of spiral ganglion neurons and their synapses forms a basis for regenerative approaches. In this review we critically present the current experimental findings on auditory neuron replacement. We discuss the latest advances with a focus on (a) exogenous stem cell transplantation into the cochlea for neural replacement, (b) expression of local guidance signals in the cochlea after loss of auditory neurons, (c) the possibility of neural replacement from an endogenous cell source, and (d) functional changes from cell engraftment. PMID:23370457
8. Psychophysical and Neural Correlates of Auditory Attraction and Aversion
Patten, Kristopher Jakob
This study explores the psychophysical and neural processes associated with the perception of sounds as either pleasant or aversive. The underlying psychophysical theory is based on auditory scene analysis, the process through which listeners parse auditory signals into individual acoustic sources. The first experiment tests and confirms that a self-rated pleasantness continuum reliably exists for 20 various stimuli (r = .48). In addition, the pleasantness continuum correlated with the physical acoustic characteristics of consonance/dissonance (r = .78), which can facilitate auditory parsing processes. The second experiment uses an fMRI block design to test blood oxygen level dependent (BOLD) changes elicited by a subset of 5 exemplar stimuli chosen from Experiment 1 that are evenly distributed over the pleasantness continuum. Specifically, it tests and confirms that the pleasantness continuum produces systematic changes in brain activity for unpleasant acoustic stimuli beyond what occurs with pleasant auditory stimuli. Results revealed that the combination of two positively and two negatively valenced experimental sounds compared to one neutral baseline control elicited BOLD increases in the primary auditory cortex, specifically the bilateral superior temporal gyrus, and left dorsomedial prefrontal cortex; the latter being consistent with a frontal decision-making process common in identification tasks. The negatively-valenced stimuli yielded additional BOLD increases in the left insula, which typically indicates processing of visceral emotions. The positively-valenced stimuli did not yield any significant BOLD activation, consistent with consonant, harmonic stimuli being the prototypical acoustic pattern of auditory objects that is optimal for auditory scene analysis. Both the psychophysical findings of Experiment 1 and the neural processing findings of Experiment 2 support that consonance is an important dimension of sound that is processed in a manner that aids
9. The Essential Complexity of Auditory Receptive Fields.
Thorson, Ivar L; Liénard, Jean; David, Stephen V
2015-12-01
Encoding properties of sensory neurons are commonly modeled using linear finite impulse response (FIR) filters. For the auditory system, the FIR filter is instantiated in the spectro-temporal receptive field (STRF), often in the framework of the generalized linear model. Despite widespread use of the FIR STRF, numerous formulations for linear filters are possible that require many fewer parameters, potentially permitting more efficient and accurate model estimates. To explore these alternative STRF architectures, we recorded single-unit neural activity from auditory cortex of awake ferrets during presentation of natural sound stimuli. We compared performance of > 1000 linear STRF architectures, evaluating their ability to predict neural responses to a novel natural stimulus. Many were able to outperform the FIR filter. Two basic constraints on the architecture lead to the improved performance: (1) factorization of the STRF matrix into a small number of spectral and temporal filters and (2) low-dimensional parameterization of the factorized filters. The best parameterized model was able to outperform the full FIR filter in both primary and secondary auditory cortex, despite requiring fewer than 30 parameters, about 10% of the number required by the FIR filter. After accounting for noise from finite data sampling, these STRFs were able to explain an average of 40% of A1 response variance. The simpler models permitted more straightforward interpretation of sensory tuning properties. They also showed greater benefit from incorporating nonlinear terms, such as short term plasticity, that provide theoretical advances over the linear model. Architectures that minimize parameter count while maintaining maximum predictive power provide insight into the essential degrees of freedom governing auditory cortical function. They also maximize statistical power available for characterizing additional nonlinear properties that limit current auditory models. PMID:26683490
10. Congenital factor XI deficiency in a domestic shorthair cat.
Troxel, Mark T; Brooks, Marjory B; Esterline, Meredith L
2002-01-01
A 6-month-old, female, domestic shorthair cat was examined after onychectomy and ovariohysterectomy because of bleeding from the paws. Prolonged activated partial thromboplastin time was discovered, Coagulation factor analyses revealed deficiency of factor XI coagulant activity. Plasma mixing studies indicated factor deficiency or dysfunction rather than factor inhibition. Feline factor XI deficiency in one adult cat has been previously reported but was attributed to factor XI inhibitors. The signalment, lack of primary disease, and the finding of persistent factor XI deficiency in the absence of coagulation inhibitors were considered compatible with congenital factor XI deficiency in the cat of this report. PMID:12428887
11. A critical period for auditory thalamocortical connectivity
Rinaldi Barkat, Tania; Polley, Daniel B; Hensch, Takao K
2011-01-01
connectivity by in vivo recordings and day-by-day voltage-sensitive dye imaging in an acute brain slice preparation. Passive tone-rearing modified response strength and topography in mouse primary auditory cortex (A1) during a brief, 3-d window, but did not alter tonotopic maps in the thalamus. Gene......-targeted deletion of a forebrain-specific cell-adhesion molecule (Icam5) accelerated plasticity in this critical period. Consistent with its normal role of slowing spinogenesis, loss of Icam5 induced precocious stubby spine maturation on pyramidal cell dendrites in neocortical layer 4 (L4), identifying a primary...
12. Cat Scratch Disease (For Parents)
... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth Cat Scratch Disease KidsHealth > For Parents > Cat Scratch Disease Print A A A Text Size ... Doctor en español Enfermedad por arañazo de gato Cat scratch disease is a bacterial infection that a ...
13. Tracheal collapse in two cats
Two cats examined bronchoscopically to discover the cause of tracheal collapse were found to have tracheal obstruction cranial to the collapse. Cats with this unusual sign should be examined bronchoscopically to ascertain whether there is an obstruction, as the cause in these 2 cats was distinct from the diffuse airway abnormality that causes tracheal collapse in dogs
14. Membranous nephropathy in sibling cats.
Nash, A S; Wright, N G
1983-08-20
Membranous nephropathy was diagnosed in two sibling cats from the same household. Both cases presented with the nephrotic syndrome but 33 months elapsed before the second cat became ill, by which time the first cat had been in full clinical remission for over a year. PMID:6623883
15. Central auditory development in children with cochlear implants: clinical implications.
Sharma, Anu; Dorman, Michael F
2006-01-01
A common finding in developmental neurobiology is that stimulation must be delivered to a sensory system within a narrow window of time (a sensitive period) during development in order for that sensory system to develop normally. Experiments with congenitally deaf children have allowed us to establish the existence and time limits of a sensitive period for the development of central auditory pathways in humans. Using the latency of cortical auditory evoked potentials (CAEPs) as a measure we have found that central auditory pathways are maximally plastic for a period of about 3.5 years. If the stimulation is delivered within that period CAEP latencies reach age-normal values within 3-6 months after stimulation. However, if stimulation is withheld for more than 7 years, CAEP latencies decrease significantly over a period of approximately 1 month following the onset of stimulation. They then remain constant or change very slowly over months or years. The lack of development of the central auditory system in congenitally deaf children implanted after 7 years is correlated with relatively poor development of speech and language skills [Geers, this vol, pp 50-65]. Animal models suggest that the primary auditory cortex may be functionally decoupled from higher order auditory cortex due to restricted development of inter- and intracortical connections in late-implanted children [Kral and Tillein, this vol, pp 89-108]. Another aspect of plasticity that works against late-implanted children is the reorganization of higher order cortex by other sensory modalities (e.g. vision). The hypothesis of decoupling of primary auditory cortex from higher order auditory cortex in children deprived of sound for a long time may explain the speech perception and oral language learning difficulties of children who receive an implant after the end of the sensitive period. PMID:16891837
16. Taxonomy Icon Data: domestic cat [Taxonomy Icon
Full Text Available domestic cat ... Felis silvestris cat us Chordata/Vertebrata/Mammalia/Theria/Eutheria/Carnivora Felis ... _silvestris_cat us_L.png Felis_silvestris_cat us_NL.png Felis_silves ... tris_cat us_S.png Felis_silvestris_cat us_NS.png http://biosc ...
17. Getting a CAT Scan
Full Text Available ... More Quizzes Kids' Dictionary of Medical Words En Español What Other Kids Are Reading Back-to-School ... Video) Print A A A Text Size en español Obtención de una tomografía computada (video) CAT stands ...
18. Chemodectoma in a cat
A 10-year-old, spayed female, domestic shorthair cat was presented for evaluation of a thoracic mass. Radiographs demonstrated a 4 by 5-cm mass dorsal to the heart. Cytology of specimens obtained by ultrasound-guided needle aspiration was compatible with a neuroendocrine tumor. Scintigraphy, thoracic exploratory, and histology were used to identify the mass as an aortic body chemodectoma
19. Coxofemoral luxations in cats
In a retrospective study, 79 untreated luxations of the coxofemoral joint in cats were recorded over a 12-year period. Twenty-nine of these cases were available for follow-up, of which 13 were re-examined clinically and radiologically. It was found that the maximum incidence of the injury occurred from one to three years of age. Follow-up radiographs showed that the cats had developed nearthroses of various degrees located dorsally on the ilium. The degree of nearthrosis formation was not consistently correlated with the length of the observation time. Radiological signs of decreased bone density of the proximal femur may be caused by reduced weightbearing related to changes in biomechanical function and altered blood supply in the luxated limb. Almost two-thirds of the re-examined animals presented some kind of locomotor dysfunction on clinical examination. Limb function improved with time. The best clinical results appeared to be in cats that were immature at the time of injury and developed nearthrosis similar to a normal coxofemoral joint. All the cats available to this study showed acceptable functional results and had a normal level of activity according to the owners
20. Getting a CAT Scan
Full Text Available ... More Quizzes Kids' Dictionary of Medical Words En Español What Other Kids Are Reading Movie: Digestive System ... Video) Print A A A Text Size en español Obtención de una tomografía computada (video) CAT stands ...
1. The Fishing Cat
孙雅飞; 乐伟国
2008-01-01
@@ 一、故事内容 A cat goes fishing every day. He wants to eat fish, but he can't catch any fish. One day, he goes to the river as usual. Suddenly, a fish comes out. He catches the fish and putsthe fish in the basket. He's very happy, but he forgest to put the lid on the basket.
2. Oligopsonistic Cats and Dogs
Dewit, Dr. Gerda; Leahy, Dr. Dermot
2005-01-01
We study the strategic investment behaviour of oligopsonistic rivals in the labour market. Under wage competition, firms play "puppy dog" with productivityaugmenting investment and "fat cat" with supply-enhancing investment. Under employment competition, investing strategically always involves playing "top dog".
3. Auditory Learning. Dimensions in Early Learning Series.
Zigmond, Naomi K.; Cicci, Regina
The monograph discusses the psycho-physiological operations for processing of auditory information, the structure and function of the ear, the development of auditory processes from fetal responses through discrimination, language comprehension, auditory memory, and auditory processes related to written language. Disorders of auditory learning…
4. The auditory characteristics of children with inner auditory canal stenosis.
Ai, Yu; Xu, Lei; Li, Li; Li, Jianfeng; Luo, Jianfen; Wang, Mingming; Fan, Zhaomin; Wang, Haibo
2016-07-01
Conclusions This study shows that the prevalence of auditory neuropathy spectrum disorder (ANSD) in the children with inner auditory canal (IAC) stenosis is much higher than those without IAC stenosis, regardless of whether they have other inner ear anomalies. In addition, the auditory characteristics of ANSD with IAC stenosis are significantly different from those of ANSD without any middle and inner ear malformations. Objectives To describe the auditory characteristics in children with IAC stenosis as well as to examine whether the narrow inner auditory canal is associated with ANSD. Method A total of 21 children, with inner auditory canal stenosis, participated in this study. A series of auditory tests were measured. Meanwhile, a comparative study was conducted on the auditory characteristics of ANSD, based on whether the children were associated with isolated IAC stenosis. Results Wave V in the ABR was not observed in all the patients, while cochlear microphonic (CM) response was detected in 81.1% ears with stenotic IAC. Sixteen of 19 (84.2%) ears with isolated IAC stenosis had CM response present on auditory brainstem responses (ABR) waveforms. There was no significant difference in ANSD characteristics between the children with and without isolated IAC stenosis. PMID:26981851
5. Impact of morphometry, myelinization and synaptic current strength on spike conduction in human and cat spiral ganglion neurons.
Frank Rattay
Full Text Available BACKGROUND: Our knowledge about the neural code in the auditory nerve is based to a large extent on experiments on cats. Several anatomical differences between auditory neurons in human and cat are expected to lead to functional differences in speed and safety of spike conduction. METHODOLOGY/PRINCIPAL FINDINGS: Confocal microscopy was used to systematically evaluate peripheral and central process diameters, commonness of myelination and morphology of spiral ganglion neurons (SGNs along the cochlea of three human and three cats. Based on these morphometric data, model analysis reveales that spike conduction in SGNs is characterized by four phases: a postsynaptic delay, constant velocity in the peripheral process, a presomatic delay and constant velocity in the central process. The majority of SGNs are type I, connecting the inner hair cells with the brainstem. In contrast to those of humans, type I neurons of the cat are entirely myelinated. Biophysical model evaluation showed delayed and weak spikes in the human soma region as a consequence of a lack of myelin. The simulated spike conduction times are in accordance with normal interwave latencies from auditory brainstem response recordings from man and cat. Simulated 400 pA postsynaptic currents from inner hair cell ribbon synapses were 15 times above threshold. They enforced quick and synchronous spiking. Both of these properties were not present in type II cells as they receive fewer and much weaker (∼26 pA synaptic stimuli. CONCLUSIONS/SIGNIFICANCE: Wasting synaptic energy boosts spike initiation, which guarantees the rapid transmission of temporal fine structure of auditory signals. However, a lack of myelin in the soma regions of human type I neurons causes a large delay in spike conduction in comparison with cat neurons. The absent myelin, in combination with a longer peripheral process, causes quantitative differences of temporal parameters in the electrically stimulated human cochlea
6. Prostatic carcinoma in two cats
Clinical, radiological and pathological features of two cats with prostatic carcinoma are reported. In both cats the presenting history included signs of lower urinary tract disease with haematuria and dysuria. Prostatomegaly was visible radiographically in one cat; an irregular intraprostatic urethra was seen on retrograde contrast urethrography in both cats. In one of the cats, neoplasia was suspected on the basis of a transurethral catheter biopsy. Following a poor response to palliative treatment in both cases, euthanasia was performed with histological confirmation of the diagnosis
7. The Cat nRules
Mould, R A
2004-01-01
The nRules that are developed in another paper are applied to two versions of the Schrodinger cat experiment. In version I the initially conscious cat is made unconscious by a mechanism that is initiated by a radioactive decay. In version II the initially unconscious cat is awakened by a mechanism that is initiated by a radioactive decay. In both cases an observer is permitted to check the statues of the cat at any time during the experiment. In all cases the nRules correctly and unambiguously predict the conscious experience of the cat and the observer. Keywords: brain states of observer, stochastic choice, state reduction, wave collapse.
8. Genetic testing in domestic cats.
Lyons, Leslie A
2012-12-01
Varieties of genetic tests are currently available for the domestic cat that support veterinary health care, breed management, species identification, and forensic investigations. Approximately thirty-five genes contain over fifty mutations that cause feline health problems or alterations in the cat's appearance. Specific genes, such as sweet and drug receptors, have been knocked-out of Felidae during evolution and can be used along with mtDNA markers for species identification. Both STR and SNP panels differentiate cat race, breed, and individual identity, as well as gender-specific markers to determine sex of an individual. Cat genetic tests are common offerings for commercial laboratories, allowing both the veterinary clinician and the private owner to obtain DNA test results. This article will review the genetic tests for the domestic cat, and their various applications in different fields of science. Highlighted are genetic tests specific to the individual cat, which are a part of the cat's genome. PMID:22546621
9. Isolation of Bartonella henselae DNA from the Peripheral Blood of a Patient with Cat Scratch Disease up to 4 Months after the Cat Scratch Injury
Arvand, Mardjan; Schäd, Susanne G.
2006-01-01
We report the case of a girl with cervical lymphadenitis and a persistent primary lesion of cat scratch disease (CSD). Bartonella henselae DNA was isolated from plasma samples collected 3 and 4 months after the cat scratch, indicating that recurrent and long-term shedding of Bartonella DNA into peripheral blood may occur in typical CSD.
10. The Cheshire Cat revisited
Vento, V
1998-01-01
The concept of effective field theory leads in a natural way to a construction principle for phenomenological sensible models known under the name of the Cheshire Cat Principle. We review its formulation in the chiral bag scenario and discuss its realization for the flavor singlet axial charge. Quantum effects inside the chiral bag induce a color anomaly which requires a compensating surface term to prevent breakdown of color gauge invariance. The presence of this surface term allows one to derive in a gauge-invariant way a chiral-bag version of the Shore-Veneziano two-component formula for the flavor-singlet axial charge of the proton. We show that one can obtain a striking Cheshire-Cat phenomenon with a negligibly small singlet axial charge.
11. Hemodynamic responses in human multisensory and auditory association cortex to purely visual stimulation
Baumann Simon
2007-02-01
Full Text Available Abstract Background Recent findings of a tight coupling between visual and auditory association cortices during multisensory perception in monkeys and humans raise the question whether consistent paired presentation of simple visual and auditory stimuli prompts conditioned responses in unimodal auditory regions or multimodal association cortex once visual stimuli are presented in isolation in a post-conditioning run. To address this issue fifteen healthy participants partook in a "silent" sparse temporal event-related fMRI study. In the first (visual control habituation phase they were presented with briefly red flashing visual stimuli. In the second (auditory control habituation phase they heard brief telephone ringing. In the third (conditioning phase we coincidently presented the visual stimulus (CS paired with the auditory stimulus (UCS. In the fourth phase participants either viewed flashes paired with the auditory stimulus (maintenance, CS- or viewed the visual stimulus in isolation (extinction, CS+ according to a 5:10 partial reinforcement schedule. The participants had no other task than attending to the stimuli and indicating the end of each trial by pressing a button. Results During unpaired visual presentations (preceding and following the paired presentation we observed significant brain responses beyond primary visual cortex in the bilateral posterior auditory association cortex (planum temporale, planum parietale and in the right superior temporal sulcus whereas the primary auditory regions were not involved. By contrast, the activity in auditory core regions was markedly larger when participants were presented with auditory stimuli. Conclusion These results demonstrate involvement of multisensory and auditory association areas in perception of unimodal visual stimulation which may reflect the instantaneous forming of multisensory associations and cannot be attributed to sensation of an auditory event. More importantly, we are able
12. Auditory Neuropathy: Findings of Behavioral, Physiological and Neurophysiological Tests
2006-12-01
Full Text Available Background and Aim: Auditory neuropathy (AN can be diagnosed by abnormal auditory brainstem response (ABR, in the presence of normal cochlear microphonic (CM and otoacoustic emissions (OAEs.The aim of this study was to investigate the ABR and other electrodiagnostic test results of 6 patients suspicious to AN with problems in speech recognition. Materials and Methods: this cross sectional study was conducted on 6 AN patients with different ages evaluated by pure tone audiometry, speech discrimination score (SDS , immittance audiometry. ElectroCochleoGraphy , ABR, middle latency response (MLR, Late latency response (LLR, and OAEs. Results: Behavioral pure tone audiometric tests showed moderate to profound hearing loss. SDS was so poor which is not in accordance with pure tone thresholds. All patients had normal tympanogram but absent acoustic reflexes. CMs and OAEs were within normal limits. There was no contra lateral suppression of OAEs. None of cases had normal ABR or MLR although LLR was recorded in 4. Conclusion: All patients in this study are typical cases of auditory neuropathy. Despite having abnormal input, LLR remains normal that indicates differences in auditory evoked potentials related to required neural synchrony. These findings show that auditory cortex may play a role in regulating presentation of deficient signals along auditory pathways in primary steps.
13. Auditory Discrimination and Auditory Sensory Behaviours in Autism Spectrum Disorders
Jones, Catherine R. G.; Happe, Francesca; Baird, Gillian; Simonoff, Emily; Marsden, Anita J. S.; Tregay, Jenifer; Phillips, Rebecca J.; Goswami, Usha; Thomson, Jennifer M.; Charman, Tony
2009-01-01
It has been hypothesised that auditory processing may be enhanced in autism spectrum disorders (ASD). We tested auditory discrimination ability in 72 adolescents with ASD (39 childhood autism; 33 other ASD) and 57 IQ and age-matched controls, assessing their capacity for successful discrimination of the frequency, intensity and duration…
14. Auditory and non-auditory effects of noise on health
Basner, M.; Babisch, W.; Davis, A.; Brink, M.; Clark, C.; Janssen, S.A.; Stansfeld, S.
2013-01-01
Noise is pervasive in everyday life and can cause both auditory and non-auditory health eff ects. Noise-induced hearing loss remains highly prevalent in occupational settings, and is increasingly caused by social noise exposure (eg, through personal music players). Our understanding of molecular mec
15. Hierarchical processing of auditory objects in humans.
Sukhbinder Kumar
2007-06-01
Full Text Available This work examines the computational architecture used by the brain during the analysis of the spectral envelope of sounds, an important acoustic feature for defining auditory objects. Dynamic causal modelling and Bayesian model selection were used to evaluate a family of 16 network models explaining functional magnetic resonance imaging responses in the right temporal lobe during spectral envelope analysis. The models encode different hypotheses about the effective connectivity between Heschl's Gyrus (HG, containing the primary auditory cortex, planum temporale (PT, and superior temporal sulcus (STS, and the modulation of that coupling during spectral envelope analysis. In particular, we aimed to determine whether information processing during spectral envelope analysis takes place in a serial or parallel fashion. The analysis provides strong support for a serial architecture with connections from HG to PT and from PT to STS and an increase of the HG to PT connection during spectral envelope analysis. The work supports a computational model of auditory object processing, based on the abstraction of spectro-temporal "templates" in the PT before further analysis of the abstracted form in anterior temporal lobe areas.
16. Hypermnesia using auditory input.
Allen, J
1992-07-01
The author investigated whether hypermnesia would occur with auditory input. In addition, the author examined the effects of subjects' knowledge that they would later be asked to recall the stimuli. Two groups of 26 subjects each were given three successive recall trials after they listened to an audiotape of 59 high-imagery nouns. The subjects in the uninformed group were not told that they would later be asked to remember the words; those in the informed group were. Hypermnesia was evident, but only in the uninformed group. PMID:1447564
17. Intrahemispheric cortico-cortical connections of the human auditory cortex.
Cammoun, Leila; Thiran, Jean Philippe; Griffa, Alessandra; Meuli, Reto; Hagmann, Patric; Clarke, Stephanie
2015-11-01
The human auditory cortex comprises the supratemporal plane and large parts of the temporal and parietal convexities. We have investigated the relevant intrahemispheric cortico-cortical connections using in vivo DSI tractography combined with landmark-based registration, automatic cortical parcellation and whole-brain structural connection matrices in 20 right-handed male subjects. On the supratemporal plane, the pattern of connectivity was related to the architectonically defined early-stage auditory areas. It revealed a three-tier architecture characterized by a cascade of connections from the primary auditory cortex to six adjacent non-primary areas and from there to the superior temporal gyrus. Graph theory-driven analysis confirmed the cascade-like connectivity pattern and demonstrated a strong degree of segregation and hierarchy within early-stage auditory areas. Putative higher-order areas on the temporal and parietal convexities had more widely spread local connectivity and long-range connections with the prefrontal cortex; analysis of optimal community structure revealed five distinct modules in each hemisphere. The pattern of temporo-parieto-frontal connectivity was partially asymmetrical. In conclusion, the human early-stage auditory cortical connectivity, as revealed by in vivo DSI tractography, has strong similarities with that of non-human primates. The modular architecture and hemispheric asymmetry in higher-order regions is compatible with segregated processing streams and lateralization of cognitive functions. PMID:25173473
18. Cheshire cat phenomena and quarks in nuclei
The notion of the ''Cheshire Cat'' principle in hadron structure is developed rigorously in (1+1) dimensions and approximately in (3+1) dimensions for up- and down-quark flavor systems. This phenomenon is invoked to address the issue as to whether or not direct quark-gluon signatures can be ''seen'' in low-energy nuclear phenomena. How addition of the third flavor -strangeness- can modify the Cheshire Cat property is discussed. It is proposed that one of the primary objectives of nuclear physics be to probe -and disturb- the ''vacuum'' of the strong interactions (QCD) and that for this purpose the chiral symmetry SU(3)xSU(3) can play a crucial role in normal and extreme conditions. As an illustration, kaon condensation at a density ρ>∼ 3ρ0 is discussed in terms of a toy model and is related to ''cleansing'' of the quark condensates from the vacuum
19. Partial Epilepsy with Auditory Features
J Gordon Millichap
2004-07-01
Full Text Available The clinical characteristics of 53 sporadic (S cases of idiopathic partial epilepsy with auditory features (IPEAF were analyzed and compared to previously reported familial (F cases of autosomal dominant partial epilepsy with auditory features (ADPEAF in a study at the University of Bologna, Italy.
20. Local cloning of CAT states
In this Letter we analyze the (im)possibility of the exact cloning of orthogonal three-qubit CAT states under local operation and classical communication (LOCC) with the help of a restricted entangled state. We also classify the three-qubit CAT states that can (not) be cloned under LOCC restrictions and extend the results to the n-qubit case. -- Highlights: → We analyze the (im)possibility of exact cloning of orthogonal CAT states under LOCC. → We also classify the set of CAT states that can(not) be cloned by LOCC. → No set of orthogonal CAT states can be cloned by LOCC with help of similar CAT state. → Any two orthogonal n-qubit GHZ-states can be cloned by LOCC with help of a GHZ state.
1. Idealized computational models for auditory receptive fields.
Tony Lindeberg
Full Text Available We present a theory by which idealized models of auditory receptive fields can be derived in a principled axiomatic manner, from a set of structural properties to (i enable invariance of receptive field responses under natural sound transformations and (ii ensure internal consistency between spectro-temporal receptive fields at different temporal and spectral scales. For defining a time-frequency transformation of a purely temporal sound signal, it is shown that the framework allows for a new way of deriving the Gabor and Gammatone filters as well as a novel family of generalized Gammatone filters, with additional degrees of freedom to obtain different trade-offs between the spectral selectivity and the temporal delay of time-causal temporal window functions. When applied to the definition of a second-layer of receptive fields from a spectrogram, it is shown that the framework leads to two canonical families of spectro-temporal receptive fields, in terms of spectro-temporal derivatives of either spectro-temporal Gaussian kernels for non-causal time or a cascade of time-causal first-order integrators over the temporal domain and a Gaussian filter over the logspectral domain. For each filter family, the spectro-temporal receptive fields can be either separable over the time-frequency domain or be adapted to local glissando transformations that represent variations in logarithmic frequencies over time. Within each domain of either non-causal or time-causal time, these receptive field families are derived by uniqueness from the assumptions. It is demonstrated how the presented framework allows for computation of basic auditory features for audio processing and that it leads to predictions about auditory receptive fields with good qualitative similarity to biological receptive fields measured in the inferior colliculus (ICC and primary auditory cortex (A1 of mammals.
2. The Perception of Auditory Motion.
Carlile, Simon; Leung, Johahn
2016-01-01
The growing availability of efficient and relatively inexpensive virtual auditory display technology has provided new research platforms to explore the perception of auditory motion. At the same time, deployment of these technologies in command and control as well as in entertainment roles is generating an increasing need to better understand the complex processes underlying auditory motion perception. This is a particularly challenging processing feat because it involves the rapid deconvolution of the relative change in the locations of sound sources produced by rotational and translations of the head in space (self-motion) to enable the perception of actual source motion. The fact that we perceive our auditory world to be stable despite almost continual movement of the head demonstrates the efficiency and effectiveness of this process. This review examines the acoustical basis of auditory motion perception and a wide range of psychophysical, electrophysiological, and cortical imaging studies that have probed the limits and possible mechanisms underlying this perception. PMID:27094029
3. Environmental Enrichment for Indoor Cats
Herron, Meghan E.; Buffington, C. A. Tony
2010-01-01
Recommendations to cat owners to house their cats indoors confer the responsibility to provide conditions that ensure good health and welfare. Cats maintain their natural behaviors, such as scratching, chewing, and elimination, while living indoors, and they may develop health and behavior problems when deprived of appropriate environmental outlets for these behaviors. This article divides the environment into five basic “systems” to enable identification of features that may benefit from imp...
4. Hypereosinophilic syndrome in two cats.
Takeuchi, Yoshinori; Matsuura, Shinobu; Fujino, Yasuhito; Nakajima, Mayumi; Takahashi, Masashi; Nakashima, Ko; Sakai, Yusuke; Uetsuka, Koji; Ohno, Koichi; Nakayama, Hiroyuki; Tsujimoto, Hajime
2008-10-01
Two cats showing chronic vomiting, diarrhea and weight loss were found to have leukocytosis with marked eosinophilia. Both cats were diagnosed with hypereosinophilic syndrome by the findings of increased eosinophils and their precursors in the bone marrow, eosinophilic infiltration into multiple organs, and exclusion of other causes for eosinophilia. Although cytoreductive chemotherapy with hydroxycarbamide and prednisolone was performed, these two cats died 48 days and 91 days after the initial presentation. PMID:18981665
5. Radiographic patterns of pulmonary metastasis in 25 cats
Thoracic radiographs of 25 cats with pulmonary metastatic disease and confirmed primary tumors were reviewed retrospectively. Pulmonary patterns of metastasis were divided into three categories, described as well-defined interstitial nodules, ill-defined interstitial nodules or a diffuse pulmonary pattern. The latter consisted of an alveolar pattern with or without ill-defined pulmonary nodules and/or pleural effusion. More cats presented with pulmonary metastatic disease in the category of either ill-defined nodules (n = 10) or a diffuse pattern (n = 7). Within this group, the most commonly represented primary tumor was mammary gland adenocarcinoma
6. Environmental enrichment for indoor cats.
Herron, Meghan E; Buffington, C A Tony
2010-12-01
Recommendations to cat owners to house their cats indoors confer the responsibility to provide conditions that ensure good health and welfare. Cats maintain their natural behaviors, such as scratching, chewing, and elimination, while living indoors, and they may develop health and behavior problems when deprived of appropriate environmental outlets for these behaviors. This article divides the environment into five basic "systems" to enable identification of features that may benefit from improvement. It also addresses practical means of meeting cats' needs in each of these systems. PMID:21882164
7. The Cat nRules
Mould, Richard A
2004-01-01
The nRules that are developed in another paper are applied to two versions of the Schrodinger cat experiment. In version I the initially conscious cat is made unconscious by a mechanism that is initiated by a radioactive decay. In version II the initially unconscious cat is awakened by a mechanism that is initiated by a radioactive decay. In both cases an observer is permitted to check the statues of the cat at any time during the experiment. In all cases the nRules correctly and unambiguousl...
8. Peripheral Auditory Mechanisms
Hall, J; Hubbard, A; Neely, S; Tubis, A
1986-01-01
How weIl can we model experimental observations of the peripheral auditory system'? What theoretical predictions can we make that might be tested'? It was with these questions in mind that we organized the 1985 Mechanics of Hearing Workshop, to bring together auditory researchers to compare models with experimental observations. Tbe workshop forum was inspired by the very successful 1983 Mechanics of Hearing Workshop in Delft [1]. Boston University was chosen as the site of our meeting because of the Boston area's role as a center for hearing research in this country. We made a special effort at this meeting to attract students from around the world, because without students this field will not progress. Financial support for the workshop was provided in part by grant BNS- 8412878 from the National Science Foundation. Modeling is a traditional strategy in science and plays an important role in the scientific method. Models are the bridge between theory and experiment. Tbey test the assumptions made in experim...
9. Evoked potentials in immobilized cats to a combination of clicks with painful electrocutaneous stimuli
Gilinskiy, M. A.; Korsakov, I. A.
1979-01-01
Averaged evoked potentials in the auditory, somatosensory, and motor cortical zones, as well as in the mesencephalic reticular formation were recorded in acute experiments on nonanesthetized, immobilized cats. Omission of the painful stimulus after a number of pairings resulted in the appearance of a delayed evoked potential, often resembling the late phases of the response to the painful stimulus. The characteristics of this response are discussed in comparison with conditioned changes of the sensory potential amplitudes.
10. cats and dogs
颜玉秀
2003-01-01
有这样一则英语成语:“To rain cats anddogs.”如果望文生义,则会被译为“下猫下狗”,因而会弄出许多笑话来,这应当是值得引以为戒的。其实这句成语的真正含义是:“下倾盆大雨”。那么下雨为什么会与cats和dogs联系在一起呢?
11. EzCatDB: M00143 [EzCatDB
Full Text Available http://ezcatdb.cbrc.jp/EzCatDB/search/get.do?dbcode=M00143 EzCatDB M00143 0) { response = "?" + ... 1995 Volume 34 Pages 955-64 Authors Mimeault M, De Lean ... A, Lafleur M, Bonenfant D, Fournier A Title Evalua ...
12. Auditory distance perception in humans: a review of cues, development, neuronal bases, and effects of sensory loss.
Kolarik, Andrew J; Moore, Brian C J; Zahorik, Pavel; Cirstea, Silvia; Pardhan, Shahina
2016-02-01
Auditory distance perception plays a major role in spatial awareness, enabling location of objects and avoidance of obstacles in the environment. However, it remains under-researched relative to studies of the directional aspect of sound localization. This review focuses on the following four aspects of auditory distance perception: cue processing, development, consequences of visual and auditory loss, and neurological bases. The several auditory distance cues vary in their effective ranges in peripersonal and extrapersonal space. The primary cues are sound level, reverberation, and frequency. Nonperceptual factors, including the importance of the auditory event to the listener, also can affect perceived distance. Basic internal representations of auditory distance emerge at approximately 6 months of age in humans. Although visual information plays an important role in calibrating auditory space, sensorimotor contingencies can be used for calibration when vision is unavailable. Blind individuals often manifest supranormal abilities to judge relative distance but show a deficit in absolute distance judgments. Following hearing loss, the use of auditory level as a distance cue remains robust, while the reverberation cue becomes less effective. Previous studies have not found evidence that hearing-aid processing affects perceived auditory distance. Studies investigating the brain areas involved in processing different acoustic distance cues are described. Finally, suggestions are given for further research on auditory distance perception, including broader investigation of how background noise and multiple sound sources affect perceived auditory distance for those with sensory loss. PMID:26590050
13. Germinoma in the Internal Auditory Canal Mimicking a Vestibular Schwannoma
Rubén Martín-Hernández
2014-01-01
Full Text Available The appearance of a primary germinoma in the central nervous system but not on or near the midline or within the brain is exceptional. It may occur at any age; however, it is rare in patients over 50 years old. Only a handful of cases of germinomas located in the cerebellopontine angle were presented, but to our knowledge, there has been no description of an isolated germinoma in the internal auditory canal. We report a case of germinoma in the internal auditory canal in a 51-year-old man simulating the clinical and radiological characteristics of a vestibular schwannoma.
14. Forelimb and hindlimb ground reaction forces of walking cats: Assessment and comparison with walking dogs
Corbee, Ronald; Hazewinkel, Herman; Doornenbal, Arie; Maas, Huub
2014-01-01
The primary aim of this study was to assess the potential of force plate analysis for describing the stride cycle of the cat. The secondary aim was to define differences in feline and canine locomotion based on force plate characteristics. Ground reaction forces of 24 healthy cats were measured and
15. Toxoplasmosis: An Important Message for Cat Owners
... role do cats play in the spread of toxoplasmosis? Cats get Toxoplasma infection by eating infected rodents, ... an infected cat may have defecated. What is toxoplasmosis? Toxoplasmosis is an infection caused by a microscopic ...
16. Accelerator programme at CAT
The Accelerator Programme at the Centre for Advanced Technology (CAT), Indore, has very broad based concept under which all types of accelerators are to be taken up for design and fabrication. This centre will be housing a wide variety of accelerators to serve as a common facility for the universities, national laboratories in addition to laboratories under the Department of Atomic Energy. In the first phase of the programme, a series of electron accelerators are designed and fabricated. They are synchrotron radiation sources of 450 MeV (INDUS-I) and of 2 GeV (INDUS-II), microtron upto energy of 20 MeV, linear accelerator upto 20 MeV, and DC Accelerator for industrial irradiation upto 750 KeV and 20 KW. A proton accelerator of 300 MeV with 20 MeV linac injector is also designed. CAT is also developing a strong base for support technologies like ultra high vacuum, radio frequency and microwaves, DC pulsed and superconducting magnets, power supplies and controls etc. These technologies are very useful for other industrial applications also. To develop user groups to utilise INDUS-II synchrotron radiation source, a batch production of rotating Anode X-ray generators with power supplies has been initiated. So also, the sputter ion pumps, electron guns, turbo molecular pumps are brought into batch production. (author)
17. CONTRACT ADMINISTRATIVE TRACKING SYSTEM (CATS)
The Contract Administrative Tracking System (CATS) was developed in response to an ORD NHEERL, Mid-Continent Ecology Division (MED)-recognized need for an automated tracking and retrieval system for Cost Reimbursable Level of Effort (CR/LOE) Contracts. CATS is an Oracle-based app...
18. College Students and Their Cats
Weinstein, Lawrence; Alexander, Ralph
2010-01-01
Twenty-two Siamese and 32 mixed breed cats' personalities were rated by their respective college student owners and compared. Further, the owners' self rated personality traits were correlated with the pets'; significant Siamese and Mixed differences and correlations were obtained. These are the first data to examine breed of cat on a personality…
19. [Glomerulonephritis in dogs and cats].
Reinacher, M; Frese, K
1991-04-01
Immunohistology and special staining of plastic sections allow diagnosis and differentiation of subtypes of glomerulonephritis in dogs. Frequency and clinical importance of these forms of glomerulonephritis vary significantly. In cats, glomerulonephritis occurs frequently in FIV-positive cats but is rare in animals suffering from persistent FeLV infection or FIP. PMID:2068715
20. Hierarchical auditory processing directed rostrally along the monkey's supratemporal plane.
Kikuchi, Yukiko; Horwitz, Barry; Mishkin, Mortimer
2010-09-29
Connectional anatomical evidence suggests that the auditory core, containing the tonotopic areas A1, R, and RT, constitutes the first stage of auditory cortical processing, with feedforward projections from core outward, first to the surrounding auditory belt and then to the parabelt. Connectional evidence also raises the possibility that the core itself is serially organized, with feedforward projections from A1 to R and with additional projections, although of unknown feed direction, from R to RT. We hypothesized that area RT together with more rostral parts of the supratemporal plane (rSTP) form the anterior extension of a rostrally directed stimulus quality processing stream originating in the auditory core area A1. Here, we analyzed auditory responses of single neurons in three different sectors distributed caudorostrally along the supratemporal plane (STP): sector I, mainly area A1; sector II, mainly area RT; and sector III, principally RTp (the rostrotemporal polar area), including cortex located 3 mm from the temporal tip. Mean onset latency of excitation responses and stimulus selectivity to monkey calls and other sounds, both simple and complex, increased progressively from sector I to III. Also, whereas cells in sector I responded with significantly higher firing rates to the "other" sounds than to monkey calls, those in sectors II and III responded at the same rate to both stimulus types. The pattern of results supports the proposal that the STP contains a rostrally directed, hierarchically organized auditory processing stream, with gradually increasing stimulus selectivity, and that this stream extends from the primary auditory area to the temporal pole. PMID:20881120
1. Auditory perspective taking.
Martinson, Eric; Brock, Derek
2013-06-01
Effective communication with a mobile robot using speech is a difficult problem even when you can control the auditory scene. Robot self-noise or ego noise, echoes and reverberation, and human interference are all common sources of decreased intelligibility. Moreover, in real-world settings, these problems are routinely aggravated by a variety of sources of background noise. Military scenarios can be punctuated by high decibel noise from materiel and weaponry that would easily overwhelm a robot's normal speaking volume. Moreover, in nonmilitary settings, fans, computers, alarms, and transportation noise can cause enough interference to make a traditional speech interface unusable. This work presents and evaluates a prototype robotic interface that uses perspective taking to estimate the effectiveness of its own speech presentation and takes steps to improve intelligibility for human listeners. PMID:23096077
2. Tactile feedback improves auditory spatial localization
Gori, Monica; Vercillo, Tiziana; Sandini, Giulio; Burr, David
2014-01-01
Our recent studies suggest that congenitally blind adults have severely impaired thresholds in an auditory spatial bisection task, pointing to the importance of vision in constructing complex auditory spatial maps (Gori et al., 2014). To explore strategies that may improve the auditory spatial sense in visually impaired people, we investigated the impact of tactile feedback on spatial auditory localization in 48 blindfolded sighted subjects. We measured auditory spatial bisection thresholds b...
3. Tactile feedback improves auditory spatial localization
Monica eGori; Tiziana eVercillo; Giulio eSandini; David eBurr
2014-01-01
Our recent studies suggest that congenitally blind adults have severely impaired thresholds in an auditory spatial-bisection task, pointing to the importance of vision in constructing complex auditory spatial maps (Gori et al., 2014). To explore strategies that may improve the auditory spatial sense in visually impaired people, we investigated the impact of tactile feedback on spatial auditory localization in 48 blindfolded sighted subjects. We measured auditory spatial bisection thresholds b...
4. Peritoneopericardial diaphragmatic hernia in cats
Peritoneopericardial diaphragmatic hernia in a cat is often an incidental finding on a routine thoracic or abdominal radiograph. Clinical signs are nonspecific-usually respiratory (dyspnea) or gastrointestinal(vomiting or diarrhea). Some of the cats with this anomaly are asymptomatic. The physical examination may be normal: muffled heart sounds are the most common abnormality noted during a physical examination. Cats of many breeds are affected, although 26% of reported cases were inPersians. Age of the cat at diagnosis ranged from 6 days to 14 years. Thirty of the 52 reported cases were in females. Diagnostic studies used to confirm the diagnosis included echocardiography, upper gastrointestinal study, ultrasonography, angiography, positive-contrast peritoneography, and laparotomy. Surgical correction was reportedly successful in 22 of 25 cats
5. Auditory short-term memory in the primate auditory cortex.
Scott, Brian H; Mishkin, Mortimer
2016-06-01
Sounds are fleeting, and assembling the sequence of inputs at the ear into a coherent percept requires auditory memory across various time scales. Auditory short-term memory comprises at least two components: an active ׳working memory' bolstered by rehearsal, and a sensory trace that may be passively retained. Working memory relies on representations recalled from long-term memory, and their rehearsal may require phonological mechanisms unique to humans. The sensory component, passive short-term memory (pSTM), is tractable to study in nonhuman primates, whose brain architecture and behavioral repertoire are comparable to our own. This review discusses recent advances in the behavioral and neurophysiological study of auditory memory with a focus on single-unit recordings from macaque monkeys performing delayed-match-to-sample (DMS) tasks. Monkeys appear to employ pSTM to solve these tasks, as evidenced by the impact of interfering stimuli on memory performance. In several regards, pSTM in monkeys resembles pitch memory in humans, and may engage similar neural mechanisms. Neural correlates of DMS performance have been observed throughout the auditory and prefrontal cortex, defining a network of areas supporting auditory STM with parallels to that supporting visual STM. These correlates include persistent neural firing, or a suppression of firing, during the delay period of the memory task, as well as suppression or (less commonly) enhancement of sensory responses when a sound is repeated as a ׳match' stimulus. Auditory STM is supported by a distributed temporo-frontal network in which sensitivity to stimulus history is an intrinsic feature of auditory processing. This article is part of a Special Issue entitled SI: Auditory working memory. PMID:26541581
6. Auditory and non-auditory effects of noise on health
Basner, Mathias; Babisch, Wolfgang; Davis, Adrian; Brink, Mark; Clark, Charlotte; Janssen, Sabine; Stansfeld, Stephen
2013-01-01
Noise is pervasive in everyday life and can cause both auditory and non-auditory health effects. Noise-induced hearing loss remains highly prevalent in occupational settings, and is increasingly caused by social noise exposure (eg, through personal music players). Our understanding of molecular mechanisms involved in noise-induced hair-cell and nerve damage has substantially increased, and preventive and therapeutic drugs will probably become available within 10 years. Evidence of the non-aud...
7. Robust speech features representation based on computational auditory model
LU Xugang; JIA Chuan; DANG Jianwu
2004-01-01
A speech signal processing and features extracting method based on computational auditory model is proposed. The computational model is based on psychological, physiological knowledge and digital signal processing methods. In each stage of a hearing perception system, there is a corresponding computational model to simulate its function. Based on this model, speech features are extracted. In each stage, the features in different kinds of level are extracted. A further processing for primary auditory spectrum based on lateral inhibition is proposed to extract much more robust speech features. All these features can be regarded as the internal representations of speech stimulation in hearing system. The robust speech recognition experiments are conducted to test the robustness of the features. Results show that the representations based on the proposed computational auditory model are robust representations for speech signals.
8. There's no ball without noise: cats' prediction of an object from noise.
Takagi, Saho; Arahori, Minori; Chijiiwa, Hitomi; Tsuzuki, Mana; Hataji, Yuya; Fujita, Kazuo
2016-09-01
We used an expectancy violation procedure to ask whether cats could use a causal rule to infer the presence of an unseen object on hearing the noise it made inside a container and predict its appearance when the container was turned over. We presented cats with either an object dropping out of an opaque container or no object dropping out (turning-over phase) after producing either a rattling sound by shaking the container with the object inside, or no sound (shaking phase). The cats were then allowed to freely explore the experimental environment (exploration phase). The relation between the sound and the object matched with physical laws in half of the trials (congruent condition) and mismatched in the other half (incongruent condition). Inferring the presence of an unseen object from the noise was predicted to result in longer looking time in the incongruent condition. The prediction was supported by the cats' behavior during the turning-over phase. The results suggest that cats used a causal-logical understanding of auditory stimuli to predict the appearance of invisible objects. The ecology of cats' natural hunting style may favor the ability for inference on the basis of sounds. PMID:27299293
9. Auditory Processing Disorder in Children
... free publications Find organizations Related Topics Auditory Neuropathy Autism Spectrum Disorder: Communication Problems in Children Dysphagia Quick ... NIH… Turning Discovery Into Health ® National Institute on Deafness and Other Communication Disorders 31 Center Drive, MSC ...
10. Auditory Processing Disorder (For Parents)
... and school. A positive, realistic attitude and healthy self-esteem in a child with APD can work wonders. And kids with APD can go on to ... Parents MORE ON THIS TOPIC Auditory Processing Disorder Special ...
11. Like herding cats.
Muller-Smith, P
1997-12-01
In an effort to be a good manager, it is easy to lose sight of the fact that knowledge workers require a unique approach from their manager. Because nurses are independent and capable individuals that prosper in an environment that recognizes them as knowledge workers, nurse managers often find that traditional management techniques are not sufficient. Trying to manage all of the nurses on a unit as a single group is much like trying to herd cats. It might be less frustrating for the nurse manager to lead gently rather than manage with a firm hand. Warren Bennis suggests that this approach may provide a valuable key to successfully managing in a world of constant change. PMID:9464034
12. The auditory and non-auditory brain areas involved in tinnitus. An emergent property of multiple parallel overlapping subnetworks.
Vanneste, Sven; De Ridder, Dirk
2012-01-01
Tinnitus is the perception of a sound in the absence of an external sound source. It is characterized by sensory components such as the perceived loudness, the lateralization, the tinnitus type (pure tone, noise-like) and associated emotional components, such as distress and mood changes. Source localization of quantitative electroencephalography (qEEG) data demonstrate the involvement of auditory brain areas as well as several non-auditory brain areas such as the anterior cingulate cortex (dorsal and subgenual), auditory cortex (primary and secondary), dorsal lateral prefrontal cortex, insula, supplementary motor area, orbitofrontal cortex (including the inferior frontal gyrus), parahippocampus, posterior cingulate cortex and the precuneus, in different aspects of tinnitus. Explaining these non-auditory brain areas as constituents of separable subnetworks, each reflecting a specific aspect of the tinnitus percept increases the explanatory power of the non-auditory brain areas involvement in tinnitus. Thus, the unified percept of tinnitus can be considered an emergent property of multiple parallel dynamically changing and partially overlapping subnetworks, each with a specific spontaneous oscillatory pattern and functional connectivity signature. PMID:22586375
13. The auditory and non-auditory brain areas involved in tinnitus. An emergent property of multiple parallel overlapping subnetworks.
Sven Vanneste
2012-05-01
Full Text Available Tinnitus is the perception of a sound in the absence of an external sound source. It is characterized by sensory components such as the perceived loudness, the lateralization, the tinnitus type (pure tone, noise-like and associated emotional components, such as distress and mood changes. Source localization of qEEG data demonstrate the involvement of auditory brain areas as well as several non-auditory brain areas such as the anterior cingulate cortex (dorsal and subgenual, auditory cortex (primary and secondary, dorsal lateral prefrontal cortex, insula, supplementary motor area, orbitofrontal cortex (including the inferior frontal gyrus, parahippocampus, posterior cingulate cortex and the precuneus, in different aspects of tinnitus. Explaining these non-auditory brain areas as constituents of separable subnetworks, each reflecting a specific aspect of the tinnitus percept increases the explanatory power of the non-auditory brain areas involvement in tinnitus. Thus the unified percept of tinnitus can be considered an emergent property of multiple parallel dynamically changing and partially overlapping subnetworks, each with a specific spontaneous oscillatory pattern and functional connectivity signature.
14. Enhancement and distortion in the temporal representation of sounds in the ventral cochlear nucleus of chinchillas and cats.
Alberto Recio-Spinoso
Full Text Available A subset of neurons in the cochlear nucleus (CN of the auditory brainstem has the ability to enhance the auditory nerve's temporal representation of stimulating sounds. These neurons reside in the ventral region of the CN (VCN and are usually known as highly synchronized, or high-sync, neurons. Most published reports about the existence and properties of high-sync neurons are based on recordings performed on a VCN output tract--not the VCN itself--of cats. In other species, comprehensive studies detailing the properties of high-sync neurons, or even acknowledging their existence, are missing.Examination of the responses of a population of VCN neurons in chinchillas revealed that a subset of those neurons have temporal properties similar to high-sync neurons in the cat. Phase locking and entrainment--the ability of a neuron to fire action potentials at a certain stimulus phase and at almost every stimulus period, respectively--have similar maximum values in cats and chinchillas. Ranges of characteristic frequencies for high-sync neurons in chinchillas and cats extend up to 600 and 1000 Hz, respectively. Enhancement of temporal processing relative to auditory nerve fibers (ANFs, which has been shown previously in cats using tonal and white-noise stimuli, is also demonstrated here in the responses of VCN neurons to synthetic and spoken vowel sounds.Along with the large amount of phase locking displayed by some VCN neurons there occurs a deterioration in the spectral representation of the stimuli (tones or vowels. High-sync neurons exhibit a greater distortion in their responses to tones or vowels than do other types of VCN neurons and auditory nerve fibers.Standard deviations of first-spike latency measured in responses of high-sync neurons are lower than similar values measured in ANFs' responses. This might indicate a role of high-sync neurons in other tasks beyond sound localization.
15. Short colon in a cat
An 11-year-old male Japanese domestic cat was referred to the veterinary hospital with a chronic diarrhea and signs of pain and vocalization when defecating. The cat has discharged unformed feces throughout his life. Morphological diagnosis of short colon was made radiographically after barium enema. The ileocolic junction and cecum was located to the left of the midline at the proximal end of the descending colon. Additional endoscopic examination demonstrated the difference in visual structures of the mucosal surface and in histological structures on mucosal biopsy specimens, between the colon and ileum. This is the first report of short colon in a cat in Japan
16. A songbird forebrain area potentially involved in auditory discrimination and memory formation
Raphael Pinaud; Thomas A Terleph
2008-03-01
Songbirds rely on auditory processing of natural communication signals for a number of social behaviors, including mate selection, individual recognition and the rare behavior of vocal learning – the ability to learn vocalizations through imitation of an adult model, rather than by instinct. Like mammals, songbirds possess a set of interconnected ascending and descending auditory brain pathways that process acoustic information and that are presumably involved in the perceptual processing of vocal communication signals. Most auditory areas studied to date are located in the caudomedial forebrain of the songbird and include the thalamo-recipient field L (subfields L1, L2 and L3), the caudomedial and caudolateral mesopallium (CMM and CLM, respectively) and the caudomedial nidopallium (NCM). This review focuses on NCM, an auditory area previously proposed to be analogous to parts of the primary auditory cortex in mammals. Stimulation of songbirds with auditory stimuli drives vigorous electrophysiological responses and the expression of several activity-regulated genes in NCM. Interestingly, NCM neurons are tuned to species-specific songs and undergo some forms of experience-dependent plasticity in-vivo. These activity-dependent changes may underlie long-term modifications in the functional performance of NCM and constitute a potential neural substrate for auditory discrimination. We end this review by discussing evidence that suggests that NCM may be a site of auditory memory formation and/or storage.
17. The impact of educational level on performance on auditory processing tests
Cristina F.B. Murphy
2016-03-01
Full Text Available Research has demonstrated that a higher level of education is associated with better performance on cognitive tests among middle-aged and elderly people. However, the effects of education on auditory processing skills have not yet been evaluated. Previous demonstrations of sensory-cognitive interactions in the aging process indicate the potential importance of this topic. Therefore, the primary purpose of this study was to investigate the performance of middle-aged and elderly people with different levels of formal education on auditory processing tests. A total of 177 adults with no evidence of cognitive, psychological or neurological conditions took part in the research. The participants completed a series of auditory assessments, including dichotic digit, frequency pattern and speech-in-noise tests. A working memory test was also performed to investigate the extent to which auditory processing and cognitive performance were associated. The results demonstrated positive but weak correlations between years of schooling and performance on all of the tests applied. The factor years of schooling was also one of the best predictors of frequency pattern and speech-in-noise test performance. Additionally, performance on the working memory, frequency pattern and dichotic digit tests was also correlated, suggesting that the influence of educational level on auditory processing performance might be associated with the cognitive demand of the auditory processing tests rather than auditory sensory aspects itself. Longitudinal research is required to investigate the causal relationship between educational level and auditory processing skills.
18. Psychology of auditory perception.
Lotto, Andrew; Holt, Lori
2011-09-01
Audition is often treated as a 'secondary' sensory system behind vision in the study of cognitive science. In this review, we focus on three seemingly simple perceptual tasks to demonstrate the complexity of perceptual-cognitive processing involved in everyday audition. After providing a short overview of the characteristics of sound and their neural encoding, we present a description of the perceptual task of segregating multiple sound events that are mixed together in the signal reaching the ears. Then, we discuss the ability to localize the sound source in the environment. Finally, we provide some data and theory on how listeners categorize complex sounds, such as speech. In particular, we present research on how listeners weigh multiple acoustic cues in making a categorization decision. One conclusion of this review is that it is time for auditory cognitive science to be developed to match what has been done in vision in order for us to better understand how humans communicate with speech and music. WIREs Cogni Sci 2011 2 479-489 DOI: 10.1002/wcs.123 For further resources related to this article, please visit the WIREs website. PMID:26302301
19. Fundamentals of ServCat
US Fish and Wildlife Service, Department of the Interior — This training manual for the U.S. Fish and Wildlife Service Catalog (ServCat) provides detailed instructions on searching for records, creating records, and...
20. NRPC ServCat priorities
US Fish and Wildlife Service, Department of the Interior — This document lists the Natural Resource Program Centers priority ServCat documents. It is recommended that these documents which include annual narrative reports,...
1. Properties of squeezed Schroedinger cats
In this article we investigate some statistical properties of the even and odd squeezed (squeezed Schroedinger cat) states. The quasi-probability distribution functions especially W(α) and Q(α) are calculated and discussed for these states. The phase distribution function is discussed. A generation scheme is proposed for either the squeezed generalized Schroedinger cat, or the squeezed number state. (author). 35 refs, 5 figs
2. Echocardiographic Findings in 11 Cats with Acromegaly
Myers, J A; Lunn, K.F.; Bright, J.M.
2014-01-01
Background Information regarding cardiac changes in domestic cats with acromegaly is limited. Hypothesis/Objectives The objective of this study was to describe the echocardiographic findings in cats with acromegaly. Animals Eighteen cats diagnosed with acromegaly at Colorado State University between 2008 and 2012. Of these 18 cats, 11 had echocardiography performed. Methods A retrospective review of medical records was made to identify cats with acromegaly that also had echocardiography perfo...
2016-01-01
In this note I briefly discuss the Schrodinger's cat Gedankenexperiment. By analysing the information flow in the system I show that no entanglement exists between the atom and the cat. The atom and the cat are connected only through a classical information channel (detector clicks $\\rightarrow$ poison is released $\\rightarrow$ cat is dead). No amount of local operations and classical communication can entangle the atom and the cat. Consequently, the paradox disappears.
4. Acquired retinal folds in the cat.
MacMillan, A D
1976-06-01
Retinal folds were found in 5 cats. The apparent cause of the folding was varied: in 1 cat the folds appeared after a localized retinal detachment; in 2 cats the condition accompanied other intraocular abnormalities associated with feline infectious peritonitis; 1 cat had active keratitis, and the retinal changes were thought to have been injury related; and 1 cat, bilaterally affected, had chronic glomerulonephritis. PMID:945253
5. Auditory and non-auditory effects of noise on health.
Basner, Mathias; Babisch, Wolfgang; Davis, Adrian; Brink, Mark; Clark, Charlotte; Janssen, Sabine; Stansfeld, Stephen
2014-04-12
Noise is pervasive in everyday life and can cause both auditory and non-auditory health effects. Noise-induced hearing loss remains highly prevalent in occupational settings, and is increasingly caused by social noise exposure (eg, through personal music players). Our understanding of molecular mechanisms involved in noise-induced hair-cell and nerve damage has substantially increased, and preventive and therapeutic drugs will probably become available within 10 years. Evidence of the non-auditory effects of environmental noise exposure on public health is growing. Observational and experimental studies have shown that noise exposure leads to annoyance, disturbs sleep and causes daytime sleepiness, affects patient outcomes and staff performance in hospitals, increases the occurrence of hypertension and cardiovascular disease, and impairs cognitive performance in schoolchildren. In this Review, we stress the importance of adequate noise prevention and mitigation strategies for public health. PMID:24183105
6. Intrathoracic neoplasms in the dog and cat
Weller, R.E.
1994-03-01
Very little is known regarding the epidemiology, etiology, and mechanisms of spontaneous intrathoracic neoplasia in companion animals. Much of what we know or suspect about thoracic neoplasia in animals has been extrapolated from experimentally-induced neoplasms. Most studies of thoracic neoplasia have focused on the pathology of primary and metastatic neoplasms of the lung with little attention given to diagnostic and therapeutic considerations. Although the cited incidence rate for primary respiratory tract neoplasia is low, 8.5 cases per 100,000 dogs and 5.5 cases per 100,000 cats, intrathoracic masses often attract attention out of proportion to their actual importance since they are often readily visualized on routine thoracic radiographs.
7. Individual differences in auditory abilities.
Kidd, Gary R; Watson, Charles S; Gygi, Brian
2007-07-01
Performance on 19 auditory discrimination and identification tasks was measured for 340 listeners with normal hearing. Test stimuli included single tones, sequences of tones, amplitude-modulated and rippled noise, temporal gaps, speech, and environmental sounds. Principal components analysis and structural equation modeling of the data support the existence of a general auditory ability and four specific auditory abilities. The specific abilities are (1) loudness and duration (overall energy) discrimination; (2) sensitivity to temporal envelope variation; (3) identification of highly familiar sounds (speech and nonspeech); and (4) discrimination of unfamiliar simple and complex spectral and temporal patterns. Examination of Scholastic Aptitude Test (SAT) scores for a large subset of the population revealed little or no association between general or specific auditory abilities and general intellectual ability. The findings provide a basis for research to further specify the nature of the auditory abilities. Of particular interest are results suggestive of a familiar sound recognition (FSR) ability, apparently specialized for sound recognition on the basis of limited or distorted information. This FSR ability is independent of normal variation in both spectral-temporal acuity and of general intellectual ability. PMID:17614500
8. Neuroglobin Expression in the Mammalian Auditory System.
Reuss, Stefan; Banica, Ovidiu; Elgurt, Mirra; Mitz, Stephanie; Disque-Kaiser, Ursula; Riemann, Randolf; Hill, Marco; Jaquish, Dawn V; Koehrn, Fred J; Burmester, Thorsten; Hankeln, Thomas; Woolf, Nigel K
2016-04-01
The energy-yielding pathways that provide the large amounts of metabolic energy required by inner ear sensorineural cells are poorly understood. Neuroglobin (Ngb) is a neuron-specific hemoprotein of the globin family, which is suggested to be involved in oxidative energy metabolism. Here, we present quantitative real-time reverse transcription PCR, in situ hybridization, immunohistochemical, and Western blot evidence that neuroglobin is highly expressed in the mouse and rat cochlea. For primary cochlea neurons, Ngb expression is limited to the subpopulation of type I spiral ganglion cells, those which innervate inner hair cells, while the subpopulation of type II spiral ganglion cells which innervate the outer hair cells do not express Ngb. We further investigated Ngb distribution in rat, mouse, and human auditory brainstem centers, and found that the cochlear nuclei and superior olivary complex (SOC) also express considerable amounts of Ngb. Notably, the majority of olivocochlear neurons, those which provide efferent innervation of outer hair cells as identified by neuronal tract tracing, were Ngb-immunoreactive. We also observed that neuroglobin in the SOC frequently co-localized with neuronal nitric oxide synthase, the enzyme responsible for nitric oxide production. Our findings suggest that neuroglobin is well positioned to play an important physiologic role in the oxygen homeostasis of the peripheral and central auditory nervous system, and provides the first evidence that Ngb signal differentiates the central projections of the inner and outer hair cells. PMID:25636685
9. Estimated Number of Birds Killed by House Cats (Felis catus in Canada
Peter Blancher
2013-12-01
10. Hierarchical and serial processing in the spatial auditory cortical pathway is degraded by natural aging
Juarez-Salinas, Dina L.; Engle, James R.; Navarro, Xochi O.; Gregg H Recanzone
2010-01-01
The compromised abilities to localize sounds and to understand speech are two hallmark deficits in aged individuals. The auditory cortex is necessary for these processes, yet we know little about how normal aging affects these early cortical fields. In this study, we recorded the spatial tuning of single neurons in primary (area A1) and secondary (area CL) auditory cortical areas in young and aged alert rhesus macaques. We found that the neurons of aged animals had greater spontaneous and dri...
11. A rate code for sound azimuth in monkey auditory cortex: implications for human neuroimaging studies
Werner-Reiss, Uri; Jennifer M Groh
2008-01-01
Is sound location represented in the auditory cortex of humans and monkeys? Human neuroimaging experiments have had only mixed success at demonstrating sound location sensitivity in primary auditory cortex. This is in apparent conflict with studies in monkeys and other animals, where single-unit recording studies have found stronger evidence for spatial sensitivity. Does this apparent discrepancy reflect a difference between humans and animals, or does it reflect differences in the sensitivit...
12. Auditory Hallucinations in Acute Stroke
Yair Lampl
2005-01-01
Full Text Available Auditory hallucinations are uncommon phenomena which can be directly caused by acute stroke, mostly described after lesions of the brain stem, very rarely reported after cortical strokes. The purpose of this study is to determine the frequency of this phenomenon. In a cross sectional study, 641 stroke patients were followed in the period between 1996–2000. Each patient underwent comprehensive investigation and follow-up. Four patients were found to have post cortical stroke auditory hallucinations. All of them occurred after an ischemic lesion of the right temporal lobe. After no more than four months, all patients were symptom-free and without therapy. The fact the auditory hallucinations may be of cortical origin must be taken into consideration in the treatment of stroke patients. The phenomenon may be completely reversible after a couple of months.
13. Adaptation in the auditory system: an overview
David ePérez-González; Malmierca, Manuel S.
2014-01-01
The early stages of the auditory system need to preserve the timing information of sounds in order to extract the basic features of acoustic stimuli. At the same time, different processes of neuronal adaptation occur at several levels to further process the auditory information. For instance, auditory nerve fiber responses already experience adaptation of their firing rates, a type of response that can be found in many other auditory nuclei and may be useful for emphasizing the onset of the s...
14. Reported cat bites in Dallas: characteristics of the cats, the victims, and the attack events.
Wright, J C
1990-01-01
Associated with the increased popularity of cats as pets in American households has been an increase in the number of cat bites reported to health departments. Bite reports from Dallas, TX, for 1985 were analyzed for different aspects of the cat bite event, including characteristics of the cats, the people bitten, the wounds, and the attack events. Cat bites and scratches constituted 25 percent of the 2,494 reported animal bites. Biting cats were typically stray females. People 21 to 35 years...
15. Diverse Roles of Axonemal Dyneins in Drosophila Auditory Neuron Function and Mechanical Amplification in Hearing
Karak, Somdatta; Jacobs, Julie S.; Kittelmann, Maike; Spalthoff, Christian; Katana, Radoslaw; Sivan-Loukianova, Elena; Schon, Michael A.; Kernan, Maurice J.; Eberl, Daniel F.; Göpfert, Martin C.
2015-01-01
Much like vertebrate hair cells, the chordotonal sensory neurons that mediate hearing in Drosophila are motile and amplify the mechanical input of the ear. Because the neurons bear mechanosensory primary cilia whose microtubule axonemes display dynein arms, we hypothesized that their motility is powered by dyneins. Here, we describe two axonemal dynein proteins that are required for Drosophila auditory neuron function, localize to their primary cilia, and differently contribute to mechanical amplification in hearing. Promoter fusions revealed that the two axonemal dynein genes Dmdnah3 (=CG17150) and Dmdnai2 (=CG6053) are expressed in chordotonal neurons, including the auditory ones in the fly’s ear. Null alleles of both dyneins equally abolished electrical auditory neuron responses, yet whereas mutations in Dmdnah3 facilitated mechanical amplification, amplification was abolished by mutations in Dmdnai2. Epistasis analysis revealed that Dmdnah3 acts downstream of Nan-Iav channels in controlling the amplificatory gain. Dmdnai2, in addition to being required for amplification, was essential for outer dynein arms in auditory neuron cilia. This establishes diverse roles of axonemal dyneins in Drosophila auditory neuron function and links auditory neuron motility to primary cilia and axonemal dyneins. Mutant defects in sperm competition suggest that both dyneins also function in sperm motility. PMID:26608786
16. Neural plasticity expressed in central auditory structures with and without tinnitus
Larry E Roberts
2012-05-01
Full Text Available Sensory training therapies for tinnitus are based on the assumption that, notwithstanding neural changes related to tinnitus, auditory training can alter the response properties of neurons in auditory pathways. To address this question, we investigated whether brain changes induced by sensory training in tinnitus sufferers and measured by EEG are similar to those induced in age and hearing loss matched individuals without tinnitus trained on the same auditory task. Auditory training was given using a 5 kHz 40-Hz amplitude-modulated sound that was in the tinnitus frequency region of the tinnitus subjects and enabled extraction of the 40-Hz auditory steady-state response (ASSR and P2 transient response known to localize to primary and nonprimary auditory cortex, respectively. P2 amplitude increased with training equally in participants with tinnitus and in control subjects, suggesting normal remodeling of nonprimary auditory regions in tinnitus. However, training-induced changes in the ASSR differed between the tinnitus and control groups. In controls ASSR phase advanced toward the stimulus waveform by about ten degrees over training, in agreement with previous results obtained in young normal hearing individuals. However, ASSR phase did not change significantly with training in the tinnitus group, although some participants showed phase shifts resembling controls. On the other hand, ASSR amplitude increased with training in the tinnitus group, whereas in controls this response (which is difficult to remodel in young normal hearing subjects did not change with training. These results suggest that neural changes related to tinnitus altered how neural plasticity was expressed in the region of primary but not nonprimary auditory cortex. Auditory training did not reduce tinnitus loudness although a small effect on the tinnitus spectrum was detected.
17. Music perception and cognition following bilateral lesions of auditory cortex.
Tramo, M J; Bharucha, J J; Musiek, F E
1990-01-01
We present experimental and anatomical data from a case study of impaired auditory perception following bilateral hemispheric strokes. To consider the cortical representation of sensory, perceptual, and cognitive functions mediating tonal information processing in music, pure tone sensation thresholds, spectral intonation judgments, and the associative priming of spectral intonation judgments by harmonic context were examined, and lesion localization was analyzed quantitatively using straight-line two-dimensional maps of the cortical surface reconstructed from magnetic resonance images. Despite normal pure tone sensation thresholds at 250-8000 Hz, the perception of tonal spectra was severely impaired, such that harmonic structures (major triads) were almost uniformly judged to sound dissonant; yet, the associative priming of spectral intonation judgments by harmonic context was preserved, indicating that cognitive representations of tonal hierarchies in music remained intact and accessible. Brainprints demonstrated complete bilateral lesions of the transverse gyri of Heschl and partial lesions of the right and left superior temporal gyri involving 98 and 20% of their surface areas, respectively. In the right hemisphere, there was partial sparing of the planum temporale, temporoparietal junction, and inferior parietal cortex. In the left hemisphere, all of the superior temporal region anterior to the transverse gyrus and parts of the planum temporale, temporoparietal junction, inferior parietal cortex, and insula were spared. These observations suggest that (1) sensory, perceptual, and cognitive functions mediating tonal information processing in music are neurologically dissociable; (2) complete bilateral lesions of primary auditory cortex combined with partial bilateral lesions of auditory association cortex chronically impair tonal consonance perception; (3) cognitive functions that hierarchically structure pitch information and generate harmonic expectancies
18. Modeling auditory-nerve responses to electrical stimulation
Joshi, Suyash Narendra; Dau, Torsten; Epp, Bastian
2014-01-01
Cochlear implants (CI) directly stimulate the auditory nerve (AN), bypassing the mechano-electricaltransduction in the inner ear. Trains of biphasic, charge-balanced pulses (anodic and cathodic) areused as stimuli to avoid damage of the tissue. The pulses of either polarity are capable of producing...... andcathodic stimulation of the AN of cat [4]. The models' responses to the electrical pulses of variousshapes [5] were also analyzed. It was found that, while the models can account for the ring rates inresponse to various biphasic pulse shapes, they fail to correctly describe the timing of AP in response to...... monophasic pulses. Strategies for improving the model performance with respect to correct AP timing are discussed. Eventually, a model that is able to account for correct spike timing in electrichearing will be useful for objective evaluation and improvement of CI stimulation strategies....
19. Utility of MR imaging in cat-scratch neuroretinitis
About 80% of cat-scratch disease (CSD) infections occur in children, and CSD neuroretinitis (optic neuropathy with retinal exudates in a ''macular star'' pattern) mostly occurs in children and young adults. A recent study suggested that CSD optic neuropathy has specific features on MR imaging. However, MR imaging findings in CSD neuroretinitis are not well described in the pediatric literature. We present a patient with CSD neuroretinitis in whom these specific MR imaging features preceded the macular star, a funduscopic finding strongly suggestive of neuroretinitis. This case demonstrates how knowledge of these features is important in the appropriate diagnostic work-up of optic neuropathy. MR imaging also incidentally revealed neuritis of another cranial nerve in the auditory canal - a rare manifestation of CSD. (orig.)
20. On Optimality in Auditory Information Processing
Karlsson, M
2000-01-01
We study limits for the detection and estimation of weak sinusoidal signals in the primary part of the mammalian auditory system using a stochastic Fitzhugh-Nagumo (FHN) model and an action-reaction model for synaptic plasticity. Our overall model covers the chain from a hair cell to a point just after the synaptic connection with a cell in the cochlear nucleus. The information processing performance of the system is evaluated using so called phi-divergences from statistics which quantify a dissimilarity between probability measures and are intimately related to a number of fundamental limits in statistics and information theory (IT). We show that there exists a set of parameters that can optimize several important phi-divergences simultaneously and that this set corresponds to a constant quiescent firing rate (QFR) of the spiral ganglion neuron. The optimal value of the QFR is frequency dependent but is essentially independent of the amplitude of the signal (for small amplitudes). Consequently, optimal proce...
1. ABR and auditory P300 findings inchildren with ADHD
Schochat Eliane
2002-01-01
Full Text Available Auditory processing disorders (APD, also referred as central auditory processing disorders (CAPD and attention deficit hyperactivity disorders (ADHD have become popular diagnostic entities for school age children. It has been demonstrated a high incidence of comorbid ADHD with communication disorders and auditory processing disorder. The aim of this study was to investigate ABR and P300 auditory evoked potentials in children with ADHD, in a double-blind study. Twenty-one children, ages between 7 and 10 years, with a primary diagnosis of ADHD, participated in this experiment. Results showed that all children had normal ABR with normal latency for wave V. Results also showed that among 42 ears combined 52.38% did not have P300. For the medicated subjects we observed that among 28 ears, 42.85% did not have P300 and for the non-medicated 71.43% (N = 14 ears did not have P300. Our results suggest that the medicated subjects had more presence of P300 (57.15% than the non-medicated group (28.57%, though the absence of these potentials were high among the group - 52.38%.
2. Epidural Auditory Event-Related Potentials in the Rat to Frequency and duration Deviants: Evidence of Mismatch Negativity?
TamoNakamura; WilliamRFulham
2011-01-01
The capacity of the human brain to detect deviance in the acoustic environment pre-attentively is reflected in a brain event-related potential (ERP), mismatch negativity (MMN). MMN is observed in response to the presentation of rare oddball sounds that deviate from an otherwise regular pattern of frequent background standard sounds. While the primate and cat auditory cortex (AC) exhibit MMN-like activity, it is unclear whether the rodent AC produces a deviant response that reflects deviance d...
3. Auditory Scene Analysis and sonified visual images. Does consonance negatively impact on object formation when using complex sonified stimuli?
David J Brown
2015-10-01
Full Text Available A critical task for the brain is the sensory representation and identification of perceptual objects in the world. When the visual sense is impaired, hearing and touch must take primary roles and in recent times compensatory techniques have been developed that employ the tactile or auditory system as a substitute for the visual system. Visual-to-auditory sonifications provide a complex, feature-based auditory representation that must be decoded and integrated into an object-based representation by the listener. However, we don’t yet know what role the auditory system plays in the object integration stage and whether the principles of auditory scene analysis apply. Here we used coarse sonified images in a two-tone discrimination task to test whether auditory feature-based representations of visual objects would be confounded when their features conflicted with the principles of auditory consonance. We found that listeners (N = 36 performed worse in an object recognition task when the auditory feature-based representation was harmonically consonant. We also found that this conflict was not negated with the provision of congruent audio-visual information. The findings suggest that early auditory processes of harmonic grouping dominate the object formation process and that the complexity of the signal, and additional sensory information have limited effect on this.
4. Characteristics of cats sterilized through a subsidized, reduced-cost spay-neuter program in Massachusetts and of owners who had cats sterilized through this program.
Benka, Valerie A; McCobb, Emily
2016-09-01
OBJECTIVE To determine characteristics of cats sterilized through a subsidized, reduced-cost spay-neuter program in Massachusetts and of owners who had their cats sterilized through this program. DESIGN Cross-sectional anonymous survey and telephone interviews. SAMPLE 1,188 (anonymous surveys) and 99 (telephone interviews) cat owners. PROCEDURES Owners who had a cat sterilized at clinics held between January 2006 and December 2008 were invited to complete anonymous surveys. Semistructured telephone interviews were conducted with owners who had a cat sterilized during clinics held in 2009. RESULTS Most cats had never been seen by a veterinarian previously; "too expensive" was the most common reason for this. Total annual household income was significantly associated with the number of times the cat had been examined by a veterinarian and reason why the cat had not been spayed or neutered previously. Most cats were acquired through informal means and without actively being sought, and there was often a time lag between acquisition and sterilization. Undesirable behavior and avoiding pregnancy were primary motivations for neutering and spaying, respectively. Nearly half of owners who indicated they would have had their cat sterilized through a private veterinarian if the clinic had not been available stated that the surgery would have been delayed because of cost. CONCLUSIONS AND CLINICAL RELEVANCE Findings suggested that spay-neuter decisions were related to owner income and procedure cost, that elimination of the reduced-cost spay-neuter program would likely have exacerbated the spay-delay problem, and that gradations of financial need should be considered when evaluating relationships between income and spay-neuter decisions. PMID:27556262
5. Diffusion tensor imaging of dolphin brains reveals direct auditory pathway to temporal lobe.
Berns, Gregory S; Cook, Peter F; Foxley, Sean; Jbabdi, Saad; Miller, Karla L; Marino, Lori
2015-07-22
The brains of odontocetes (toothed whales) look grossly different from their terrestrial relatives. Because of their adaptation to the aquatic environment and their reliance on echolocation, the odontocetes' auditory system is both unique and crucial to their survival. Yet, scant data exist about the functional organization of the cetacean auditory system. A predominant hypothesis is that the primary auditory cortex lies in the suprasylvian gyrus along the vertex of the hemispheres, with this position induced by expansion of 'associative' regions in lateral and caudal directions. However, the precise location of the auditory cortex and its connections are still unknown. Here, we used a novel diffusion tensor imaging (DTI) sequence in archival post-mortem brains of a common dolphin (Delphinus delphis) and a pantropical dolphin (Stenella attenuata) to map their sensory and motor systems. Using thalamic parcellation based on traditionally defined regions for the primary visual (V1) and auditory cortex (A1), we found distinct regions of the thalamus connected to V1 and A1. But in addition to suprasylvian-A1, we report here, for the first time, the auditory cortex also exists in the temporal lobe, in a region near cetacean-A2 and possibly analogous to the primary auditory cortex in related terrestrial mammals (Artiodactyla). Using probabilistic tract tracing, we found a direct pathway from the inferior colliculus to the medial geniculate nucleus to the temporal lobe near the sylvian fissure. Our results demonstrate the feasibility of post-mortem DTI in archival specimens to answer basic questions in comparative neurobiology in a way that has not previously been possible and shows a link between the cetacean auditory system and those of terrestrial mammals. Given that fresh cetacean specimens are relatively rare, the ability to measure connectivity in archival specimens opens up a plethora of possibilities for investigating neuroanatomy in cetaceans and other species
6. Auditory Cortical Plasticity Drives Training-Induced Cognitive Changes in Schizophrenia.
Dale, Corby L; Brown, Ethan G; Fisher, Melissa; Herman, Alexander B; Dowling, Anne F; Hinkley, Leighton B; Subramaniam, Karuna; Nagarajan, Srikantan S; Vinogradov, Sophia
2016-01-01
Schizophrenia is characterized by dysfunction in basic auditory processing, as well as higher-order operations of verbal learning and executive functions. We investigated whether targeted cognitive training of auditory processing improves neural responses to speech stimuli, and how these changes relate to higher-order cognitive functions. Patients with schizophrenia performed an auditory syllable identification task during magnetoencephalography before and after 50 hours of either targeted cognitive training or a computer games control. Healthy comparison subjects were assessed at baseline and after a 10 week no-contact interval. Prior to training, patients (N = 34) showed reduced M100 response in primary auditory cortex relative to healthy participants (N = 13). At reassessment, only the targeted cognitive training patient group (N = 18) exhibited increased M100 responses. Additionally, this group showed increased induced high gamma band activity within left dorsolateral prefrontal cortex immediately after stimulus presentation, and later in bilateral temporal cortices. Training-related changes in neural activity correlated with changes in executive function scores but not verbal learning and memory. These data suggest that computerized cognitive training that targets auditory and verbal learning operations enhances both sensory responses in auditory cortex as well as engagement of prefrontal regions, as indexed during an auditory processing task with low demands on working memory. This neural circuit enhancement is in turn associated with better executive function but not verbal memory. PMID:26152668
7. Free-ranging farm cats: home range size and predation on a livestock unit in Northwest Georgia.
Susanna E Kitts-Morgan
Full Text Available This study's objective was to determine seasonal and diurnal vs. nocturnal home range size, as well as predation for free-ranging farm cats at a livestock unit in Northwest Georgia. Seven adult cats were tracked with attached GPS units for up to two weeks for one spring and two summer seasons from May 2010 through August 2011. Three and five cats were tracked for up to two weeks during the fall and winter seasons, respectively. Feline scat was collected during this entire period. Cats were fed a commercial cat food daily. There was no seasonal effect (P > 0.05 on overall (95% KDE and 90% KDE or core home range size (50% KDE. Male cats tended (P = 0.08 to have larger diurnal and nocturnal core home ranges (1.09 ha compared to female cats (0.64 ha. Reproductively intact cats (n = 2 had larger (P < 0.0001 diurnal and nocturnal home ranges as compared to altered cats. Feline scat processing separated scat into prey parts, and of the 210 feline scats collected during the study, 75.24% contained hair. Of these 158 scat samples, 86 contained non-cat hair and 72 contained only cat hair. Other prey components included fragments of bone in 21.43% of scat and teeth in 12.86% of scat. Teeth were used to identify mammalian prey hunted by these cats, of which the Hispid cotton rat (Sigmodon hispidus was the primary rodent. Other targeted mammals were Peromyscus sp., Sylvilagus sp. and Microtus sp. Invertebrates and birds were less important as prey, but all mammalian prey identified in this study consisted of native animals. While the free-ranging farm cats in this study did not adjust their home range seasonally, sex and reproductive status did increase diurnal and nocturnal home range size. Ultimately, larger home ranges of free-ranging cats could negatively impact native wildlife.
8. On Schr\\"odinger's cat
de Silva, Nalin
2010-01-01
Schr\\"odinger's cat appears to have been harassed in a chamber during the past eighty years or so by interpreting the role of the observer as a person, who sets an experiment and then observes results, may be after some time. The realist position tells us that the physical processes would take place independent of the observer with well defined properties, whereas the positivist position wants us to believe that nothing can be said of a system when it is not being observed. In this paper we question both these positions and also the assumption that the atom and the cat are entangled and further whether the atom could be considered to be in a state of decay and not decay. We let the cat either out of the bag (chamber) or rest in peace with or without the atom or the observer.
9. Spatial Stream Segregation by Cats.
Javier, Lauren K; McGuire, Elizabeth A; Middlebrooks, John C
2016-06-01
Listeners can perceive interleaved sequences of sounds from two or more sources as segregated streams. In humans, physical separation of sound sources is a major factor enabling such stream segregation. Here, we examine spatial stream segregation with a psychophysical measure in domestic cats. Cats depressed a pedal to initiate a target sequence of brief sound bursts in a particular rhythm and then released the pedal when the rhythm changed. The target bursts were interleaved with a competing sequence of bursts that could differ in source location but otherwise were identical to the target bursts. This task was possible only when the sources were heard as segregated streams. When the sound bursts had broad spectra, cats could detect the rhythm change when target and competing sources were separated by as little as 9.4°. Essentially equal levels of performance were observed when frequencies were restricted to a high, 4-to-25-kHz, band in which the principal spatial cues presumably were related to sound levels. When the stimulus band was restricted from 0.4 to 1.6 kHz, leaving interaural time differences as the principal spatial cue, performance was severely degraded. The frequency sensitivity of cats in this task contrasts with that of humans, who show better spatial stream segregation with low- than with high-frequency sounds. Possible explanations for the species difference includes the smaller interaural delays available to cats due to smaller sizes of their heads and the potentially greater sound-level cues available due to the cat's frontally directed pinnae and higher audible frequency range. PMID:26993807
10. Acute lesions of primary visual cortical areas in adult cats inactivate responses of neurons in higher visual cortices%急性毁损猫的初级视区使高级视区细胞失去对视觉刺激的诱发反应
张辉; 孟建军; 王珂; 刘瑞龙; 奚敏敏; 华田苗
2012-01-01
心理物理学研究提示,初级视区毁损后的视觉残留可能是通过外纹状皮层的神经网络重组介导的,但缺少支持这一假说的电生理实验证据.采用在体细胞外单细胞记录技术,该研究分别检测了初级视区(主要包括17和18区)急性毁损猫和正常对照猫的高级视区(包括19、20和21区)神经元对不同视觉刺激的反应性.结果显示,与对照相比,急性毁损初级视区使99.3％的高级视区神经元丧失对运动光栅刺激的诱发反应,93％的神经元丧失对闪光刺激的反应.该结果表明,急性毁损成年猫的初级视皮层可能会导致其绝大部分视觉能力丧失.在幼年期实施初级视皮层毁损后,成年猫出现的残留视觉可能主要是由于手术后皮层下神经核团与外纹状皮层之间的通路重组引起的.%Psychophysical studies suggest that lateral extrastriate visual cortical areas in cats may mediate the sparing of vision largely by network reorganization following lesions of early visual cortical areas.To date,however,there is little direct physiological evidence to support this hypothesis.Using in vivo single-unit recording techniques,we examined the response of neurons in areas 19,21,and 20 to different types of visual stimulation in cats with or without acute bilateral lesions in areas 17 and 18.Our results showed that,relative to the controls,acute lesions inactivated the response of 99.3％ of neurons to moving gratings and 93％ of neurons to flickering square stimuli in areas 19,21,and 20.These results indicated that acute lesions of primary visual areas in adult cats may impair most visual abilities.Sparing of vision in cats with neonatal lesions in early visual cortical areas may result largely from a postoperative reorganization of visual pathways from subcortical nucleus to extrastriate visual cortical areas.
|
{"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": 0, "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": 0.36684268712997437, "perplexity": 8743.958429269533}, "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-2016-44/segments/1476988720760.76/warc/CC-MAIN-20161020183840-00320-ip-10-171-6-4.ec2.internal.warc.gz"}
|
http://etheses.whiterose.ac.uk/view/iau/York=2EYOR16.default.html
|
Browse by University and Academic Department
Up a level
Export as ASCII CitationBibTeXDublin CoreEndNoteHTML CitationMETSObject IDsOpenURL ContextObjectRDF+N-TriplesRDF+N3RDF+XMLReferReference Manager
Group by: Date | Creators | No Grouping
Number of items at this level: 77.
Martin, Giles D. R (2007) Classical and Quantum Radiation Reaction. PhD thesis, University of York.
Neklyudov, Mikhail (2006) Navier-Stokes equations and vector advection. PhD thesis, University of York.
Al-aadhami, Asawer (2017) Combinatorial Questions for $S\wr_{n} \mathcal{T}_n$ for a semigroup. PhD thesis, University of York.
Alfiniyah, Cicik (2017) The Role of Quorum Sensing in Bacterial Colony Dynamics. PhD thesis, University of York.
Allen, Demi Denise (2017) Mass Transference Principles and Applications in Diophantine Approximation. PhD thesis, University of York.
Anwar, Muhammad F (2011) Representations and Cohomology of Algebraic Groups. PhD thesis, University of York.
Barton, Christine H (2000) Magic squares of Lie algebras. PhD thesis, University of York.
Biniok, Johannes CG (2014) Compatible and incompatible observables in the paradigmatic multislit experiments of quantum mechanics. PhD thesis, University of York.
Box, John (2015) A Dynamic Structure for High Dimensional Covariance Matrices and its Application in Portfolio Allocation. PhD thesis, University of York.
Brewer, Sky J (2017) Results in Metric and Analytic Number Theory. PhD thesis, University of York.
Brierley, Stephen (2009) Mutually Unbiased Bases in Low Dimensions. PhD thesis, University of York.
Brown, Robert (2018) From Lie algebras to Chevalley groups. MSc by research thesis, University of York.
Bullock, David (2011) Klein-Gordon solutions on non-globally hyperbolic standard static spacetimes. PhD thesis, University of York.
Bullock, Tom (2015) From Incompatibility to Optimal Joint Measurability in Quantum Mechanics. PhD thesis, University of York.
Burrow, Jennifer (2011) Mechanistic models of recruitment variability in fish populations. PhD thesis, University of York.
Cornock, Claire (2011) Restriction Semigroups: Structure, Varieties and Presentations. PhD thesis, University of York.
Datta, Samik (2011) A mathematical analysis of marine size spectra. PhD thesis, University of York.
Dhami, Kymrun K. (2017) An evaluation on the gracefulness and colouring of graphs. MSc by research thesis, University of York.
Dhariwal, Gaurav (2017) A study of constrained Navier-Stokes equations and related problems. PhD thesis, University of York.
Dong, Wenfeng (2018) The Evaluation of Gas Sales Agreements. PhD thesis, University of York.
Draper, Christopher Peter William (2015) The geodesic Gauss map of spheres and complex projective space. PhD thesis, University of York.
Dumbrell, Edward Mark (2018) On the Rescaled Hitting Time and Return Time Distributions to Asymptotically Small Sets. PhD thesis, University of York.
Dyer, Jacob (2015) Enumeration of rooted constellations and hypermaps through quantum matrix integrals. PhD thesis, University of York.
Dyson, Charles (2011) Implementing quantum algorithms using classical electrical circuits: Deutsch, Deutsch-Jozsa and Grover. MSc by research thesis, University of York.
Faizal, Mir (2009) Perturbative Quantum Gravity and Yang-Mills Theories in de Sitter Spacetime. PhD thesis, University of York.
Ferguson, Matthew T (2013) Aspects of Dynamical Locality and Locally Covariant Canonical Quantization. PhD thesis, University of York.
Friswell, Robert Michael (2014) Harmonic Vector Fields on Pseudo-Riemannian Manifolds. PhD thesis, University of York.
Gibbons, Jos (2015) Infrared problem in the Faddeev–Popov sector in Yang–Mills Theory and Perturbative Gravity. PhD thesis, University of York.
Goodbourn, Oliver (2014) Reductive pairs arising from representations. PhD thesis, University of York.
Gunns, Jos Mary Mayo (2017) Differentiating L-functions. PhD thesis, University of York.
Harrap, Stephen (2011) Diophantine approximation: the twisted, weighted and mixed theories. PhD thesis, University of York.
Heap, Winston (2013) Moments of the Dedekind zeta function. PhD thesis, University of York.
Heaton, Rachel Ann (2009) On Schur algebras, Doty coalgebras and quasi-hereditary algebras. PhD thesis, University of York.
Hills, Daniel (2016) Generating boundary conditions for integrable field theories using defects. PhD thesis, University of York.
Hunt, David Stephen (2012) The Quantization of Linear Gravitational Perturbations and the Hadamard Condition. PhD thesis, University of York.
Hussain, Javed (2015) Analysis Of Some Deterministic and Stochastic Evolution Equations With Solutions Taking Values In An Infinite Dimensional Hilbert Manifold. PhD thesis, University of York.
Ke, Yuan (2015) Feature selection and structure specification in ultra-high dimensional semi-parametric model with an application in medical science. PhD thesis, University of York.
Kechrimparis, Spyridon (2015) Uncertainty Relations for Quantum Particles. PhD thesis, University of York.
King, Callum (2016) The spectral density for scalar �elds in de Sitter space at one-loop. MSc by research thesis, University of York.
Kou, Xiaochen (2018) An Iterative Approach for Model Selection in A Class of Semiparametric Models. PhD thesis, University of York.
Lang, Benjamin (2014) Universal constructions in algebraic and locally covariant quantum field theory. PhD thesis, University of York.
Leong, Nicol (2017) Sums of Reciprocals and the Three Distance Theorem. MSc by research thesis, University of York.
Li, Liang (2013) A STUDY OF STOCHASTIC LANDAU-LIFSCHITZ EQUATIONS. PhD thesis, University of York.
Li, Xiang (2016) Maximum Rank Correlation Estimation for Generalized Varying-Coefficient Models with Unknown Monotonic Link Function. PhD thesis, University of York.
Lock, Sarah Cloud Lauren (2017) Functional Data Analysis and QTL Detection Across Time within the Circadian Clock. MSc by research thesis, University of York.
Loveridge, Leon (2012) Quantum Measurements in the Presence of Symmetry. PhD thesis, University of York.
Lupo, Umberto (2015) Aspects of (quantum) field theory on curved spacetimes, particularly in the presence of boundaries. PhD thesis, University of York.
Martin, Samuel (2018) On the Clebsch-Gordan Problem in Prime Characteristic. PhD thesis, University of York.
McNulty, Daniel (2013) Mutually Unbiased Product Bases. PhD thesis, University of York.
Ortiz Hernandez, Leonardo (2011) Quantum Fields on BTZ Black Holes. PhD thesis, University of York.
Parini, Robert Charles (2018) Classical integrable field theories with defects and near-integrable boundaries. PhD thesis, University of York.
Potts, Thomas (2012) Properties of convolution operators on Lp(0,1). PhD thesis, University of York.
Quinn-Gregson, Thomas (2017) Homogeneity and omega-categoricity of semigroups. PhD thesis, University of York.
Regelskis, Vidas (2012) Quantum Algebras and Integrable Boundaries in AdS/CFT. PhD thesis, University of York.
Salthouse, David Georges (2013) Quasilattice-Based Models for Structural Constraints on Virus Architecture. PhD thesis, University of York.
Serrano Perdomo, Rafael Antonio (2010) Optimal control of stochastic partial differential equations in Banach spaces. PhD thesis, University of York.
Shaheen, Lubna (2011) Axiomatisability problems for $S$-acts and $S$-posets. PhD thesis, University of York.
Smith, Christopher Richard (2016) The hunt for Skewes' number. MSc by research thesis, University of York.
Stanislaus, Mariaseelan (2011) The Geodesic Gauss Map and Ruh-Vilms theorem for a Hypersurface in S^{n}. MSc by research thesis, University of York.
Stevens, Neil (2014) Concepts surrounding incompatibility in quantum physics. PhD thesis, University of York.
Strachan, Maxwell Alexander Wharton (2014) Harmonic vector fields on Riemannian manifolds. MSc by research thesis, University of York.
Sueess, Fabian (2017) Simultaneous Diophantine approximation on affine subspaces and Dirichlet improvability. PhD thesis, University of York.
Waldron, James (2014) Lie Algebroids over Differentiable Stacks. PhD thesis, University of York.
Walker, Philip (2010) Radiation and reaction in scalar quantum electrodynamics. PhD thesis, University of York.
Wang, Yanhui (2012) Beyond Regular Semigroups. PhD thesis, University of York.
Weilenmann, Mirjam (2017) Quantum Causal Structure and Quantum Thermodynamics. PhD thesis, University of York.
Xu, Zhikang (2018) Option Pricing and Hedging with Regret Optimisation. PhD thesis, University of York.
YANG, DANDAN (2014) Free idempotent generated semigroups. PhD thesis, University of York.
Yan, Hongjia (2013) Statistical Analysis of Spatial Dynamic Pattern in Spatial Data Analysis. PhD thesis, University of York.
Zafeiropoulos, Agamemnon (2017) Inhomogeneous Diophantine approximation, M_0 sets and projections of fractals. PhD thesis, University of York.
Zappa, Emilio (2015) New group theoretical methods for applications in virology and quasicrystals. PhD thesis, University of York.
Zenab, Rida-E (2014) Decomposition of semigroups into semidirect and Zappa-Sz\'{e}p products. PhD thesis, University of York.
Zhu, Jiahui (2010) A study of SPDEs w.r.t. compensated Poisson random measures and related topics. PhD thesis, University of York.
abdulkadir, dilshad (2014) J- Simple restriction ω-semigroups. MSc by research thesis, University of York.
de la Rosa, Alejandro (2017) Symmetries of integrable open boundaries in the Hubbard model and other spin chains. PhD thesis, University of York.
kok, Tayfun (2017) Stochastic Evolution Equations in Banach Spaces and Applications to the Heath-Jarrow-Morton-Musiela Equation. PhD thesis, University of York.
ul Haq, Ahsan (2012) On a class of measures on configuration spaces. PhD thesis, University of York.
This list was generated on Thu Jan 17 09:33:45 2019 GMT.
|
{"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": 0, "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": 0.6897087097167969, "perplexity": 4417.418616948304}, "config": {"markdown_headings": false, "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-2019-04/segments/1547583658988.30/warc/CC-MAIN-20190117143601-20190117165601-00599.warc.gz"}
|
https://ask.sagemath.org/answers/55473/revisions/
|
Revision history [back]
Regarding your main problem, you should not use a symbolic expression but a Python function:
sage: exp = lambda r : prod(1-2**(-i) for i in range(1,r-1))
Or, equivalently:
sage: def exp(r):
....: return prod(1-2**(-i) for i in range(1,r-1))
Then you can do:
sage: a = exp(12345)
which is a rational number with huge numerator and denominator, but you can get an approximation with:
sage: RDF(a)
0.2887880950866024
Regarding your side question, i did not see anything like that in Sage source code, so i guess you have to define such a symbolic function yourself.
|
{"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": 0.793097734451294, "perplexity": 1213.6230782581026}, "config": {"markdown_headings": false, "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-2021-39/segments/1631780058456.86/warc/CC-MAIN-20210927151238-20210927181238-00432.warc.gz"}
|
https://terrytao.wordpress.com/2009/04/
|
You are currently browsing the monthly archive for April 2009.
As discussed in previous notes, a function space norm can be viewed as a means to rigorously quantify various statistics of a function ${f: X \rightarrow {\bf C}}$. For instance, the “height” and “width” can be quantified via the ${L^p(X,\mu)}$ norms (and their relatives, such as the Lorentz norms ${\|f\|_{L^{p,q}(X,\mu)}}$). Indeed, if ${f}$ is a step function ${f = A 1_E}$, then the ${L^p}$ norm of ${f}$ is a combination ${\|f\|_{L^p(X,\mu)} = |A| \mu(E)^{1/p}}$ of the height (or amplitude) ${A}$ and the width ${\mu(E)}$.
However, there are more features of a function ${f}$ of interest than just its width and height. When the domain ${X}$ is a Euclidean space ${{\bf R}^d}$ (or domains related to Euclidean spaces, such as open subsets of ${{\bf R}^d}$, or manifolds), then another important feature of such functions (especially in PDE) is the regularity of a function, as well as the related concept of the frequency scale of a function. These terms are not rigorously defined; but roughly speaking, regularity measures how smooth a function is (or how many times one can differentiate the function before it ceases to be a function), while the frequency scale of a function measures how quickly the function oscillates (and would be inversely proportional to the wavelength). One can illustrate this informal concept with some examples:
• Let ${\phi \in C^\infty_c({\bf R})}$ be a test function that equals ${1}$ near the origin, and ${N}$ be a large number. Then the function ${f(x) := \phi(x) \sin(Nx)}$ oscillates at a wavelength of about ${1/N}$, and a frequency scale of about ${N}$. While ${f}$ is, strictly speaking, a smooth function, it becomes increasingly less smooth in the limit ${N \rightarrow \infty}$; for instance, the derivative ${f'(x) = \phi'(x) \sin(Nx) + N \phi(x) \cos(Nx)}$ grows at a roughly linear rate as ${N \rightarrow \infty}$, and the higher derivatives grow at even faster rates. So this function does not really have any regularity in the limit ${N \rightarrow \infty}$. Note however that the height and width of this function is bounded uniformly in ${N}$; so regularity and frequency scale are independent of height and width.
• Continuing the previous example, now consider the function ${g(x) := N^{-s} \phi(x) \sin(Nx)}$, where ${s \geq 0}$ is some parameter. This function also has a frequency scale of about ${N}$. But now it has a certain amount of regularity, even in the limit ${N \rightarrow \infty}$; indeed, one easily checks that the ${k^{th}}$ derivative of ${g}$ stays bounded in ${N}$ as long as ${k \leq s}$. So one could view this function as having “${s}$ degrees of regularity” in the limit ${N \rightarrow \infty}$.
• In a similar vein, the function ${N^{-s} \phi(Nx)}$ also has a frequency scale of about ${N}$, and can be viewed as having ${s}$ degrees of regularity in the limit ${N \rightarrow \infty}$.
• The function ${\phi(x) |x|^s 1_{x > 0}}$ also has about ${s}$ degrees of regularity, in the sense that it can be differentiated up to ${s}$ times before becoming unbounded. By performing a dyadic decomposition of the ${x}$ variable, one can also decompose this function into components ${\psi(2^n x) |x|^s}$ for ${n \geq 0}$, where ${\psi(x) := (\phi(x)-\phi(2x)) 1_{x>0}}$ is a bump function supported away from the origin; each such component has frequency scale about ${2^n}$ and ${s}$ degrees of regularity. Thus we see that the original function ${\phi(x) |x|^s 1_{x > 0}}$ has a range of frequency scales, ranging from about ${1}$ all the way to ${+\infty}$.
• One can of course concoct higher-dimensional analogues of these examples. For instance, the localised plane wave ${\phi(x) \sin(\xi \cdot x)}$ in ${{\bf R}^d}$, where ${\phi \in C^\infty_c({\bf R}^d)}$ is a test function, would have a frequency scale of about ${|\xi|}$.
There are a variety of function space norms that can be used to capture frequency scale (or regularity) in addition to height and width. The most common and well-known examples of such spaces are the Sobolev space norms ${\| f\|_{W^{s,p}({\bf R}^d)}}$, although there are a number of other norms with similar features (such as Hölder norms, Besov norms, and Triebel-Lizorkin norms). Very roughly speaking, the ${W^{s,p}}$ norm is like the ${L^p}$ norm, but with “${s}$ additional degrees of regularity”. For instance, in one dimension, the function ${A \phi(x/R) \sin(Nx)}$, where ${\phi}$ is a fixed test function and ${R, N}$ are large, will have a ${W^{s,p}}$ norm of about ${|A| R^{1/p} N^s}$, thus combining the “height” ${|A|}$, the “width” ${R}$, and the “frequency scale” ${N}$ of this function together. (Compare this with the ${L^p}$ norm of the same function, which is about ${|A| R^{1/p}}$.)
To a large extent, the theory of the Sobolev spaces ${W^{s,p}({\bf R}^d)}$ resembles their Lebesgue counterparts ${L^p({\bf R}^d)}$ (which are as the special case of Sobolev spaces when ${s=0}$), but with the additional benefit of being able to interact very nicely with (weak) derivatives: a first derivative ${\frac{\partial f}{\partial x_j}}$ of a function in an ${L^p}$ space usually leaves all Lebesgue spaces, but a first derivative of a function in the Sobolev space ${W^{s,p}}$ will end up in another Sobolev space ${W^{s-1,p}}$. This compatibility with the differentiation operation begins to explain why Sobolev spaces are so useful in the theory of partial differential equations. Furthermore, the regularity parameter ${s}$ in Sobolev spaces is not restricted to be a natural number; it can be any real number, and one can use fractional derivative or integration operators to move from one regularity to another. Despite the fact that most partial differential equations involve differential operators of integer order, fractional spaces are still of importance; for instance it often turns out that the Sobolev spaces which are critical (scale-invariant) for a certain PDE are of fractional order.
The uncertainty principle in Fourier analysis places a constraint between the width and frequency scale of a function; roughly speaking (and in one dimension for simplicity), the product of the two quantities has to be bounded away from zero (or to put it another way, a wave is always at least as wide as its wavelength). This constraint can be quantified as the very useful Sobolev embedding theorem, which allows one to trade regularity for integrability: a function in a Sobolev space ${W^{s,p}}$ will automatically lie in a number of other Sobolev spaces ${W^{\tilde s,\tilde p}}$ with ${\tilde s < s}$ and ${\tilde p > p}$; in particular, one can often embed Sobolev spaces into Lebesgue spaces. The trade is not reversible: one cannot start with a function with a lot of integrability and no regularity, and expect to recover regularity in a space of lower integrability. (One can already see this with the most basic example of Sobolev embedding, coming from the fundamental theorem of calculus. If a (continuously differentiable) function ${f: {\bf R} \rightarrow {\bf R}}$ has ${f'}$ in ${L^1({\bf R})}$, then we of course have ${f \in L^\infty({\bf R})}$; but the converse is far from true.)
Plancherel’s theorem reveals that Fourier-analytic tools are particularly powerful when applied to ${L^2}$ spaces. Because of this, the Fourier transform is very effective at dealing with the ${L^2}$-based Sobolev spaces ${W^{s,2}({\bf R}^d)}$, often abbreviated ${H^s({\bf R}^d)}$. Indeed, using the fact that the Fourier transform converts regularity to decay, we will see that the ${H^s({\bf R}^d)}$ spaces are nothing more than Fourier transforms of weighted ${L^2}$ spaces, and in particular enjoy a Hilbert space structure. These Sobolev spaces, and in particular the energy space ${H^1({\bf R}^d)}$, are of particular importance in any PDE that involves some sort of energy functional (this includes large classes of elliptic, parabolic, dispersive, and wave equations, and especially those equations connected to physics and/or geometry).
We will not fully develop the theory of Sobolev spaces here, as this would require the theory of singular integrals, which is beyond the scope of this course. There are of course many references for further reading; one is Stein’s “Singular integrals and differentiability properties of functions“.
Here are the video, audio, and transcript of the talk.
[Update, Apr 28: Another event at the meeting is the announcement of the new membership of the Academy for 2009. In mathematics, the new members include Alice Chang, Percy Deift, John Morgan, and Gilbert Strang; congratulations to all four, of course.]
I have received some anecdotal evidence that wordpress blogs such as this one have recently been blocked again by the “great firewall of China“. I was wondering if the readers here could confirm or disconfirm this, and also if they knew of some effective ways to circumvent this firewall, as I have been getting a number of requests on how to do so.
[Of course, by definition, if a reader is directly affected by this blockage, then they would not be able to comment here or to read about any workarounds; but perhaps they would be able to confirm the situation indirectly, and I could still pass on any relevant tips obtained here by other channels.]
[Update, June 3: A partial list of blocked sites can be found here, and a firewall tester can be found here.]
In the theory of dense graphs on ${n}$ vertices, where ${n}$ is large, a fundamental role is played by the Szemerédi regularity lemma:
Lemma 1 (Regularity lemma, standard version) Let ${G = (V,E)}$ be a graph on ${n}$ vertices, and let ${\epsilon > 0}$ and ${k_0 \geq 0}$. Then there exists a partition of the vertices ${V = V_1 \cup \ldots \cup V_k}$, with ${k_0 \leq k \leq C(k_0,\epsilon)}$ bounded below by ${k_0}$ and above by a quantity ${C(k_0,\epsilon)}$ depending only on ${k_0, \epsilon}$, obeying the following properties:
• (Equitable partition) For any ${1 \leq i,j \leq k}$, the cardinalities ${|V_i|, |V_j|}$ of ${V_i}$ and ${V_j}$ differ by at most ${1}$.
• (Regularity) For all but at most ${\epsilon k^2}$ pairs ${1 \leq i < j \leq k}$, the portion of the graph ${G}$ between ${V_i}$ and ${V_j}$ is ${\epsilon}$-regular in the sense that one has
$\displaystyle |d( A, B ) - d( V_i, V_j )| \leq \epsilon$
for any ${A \subset V_i}$ and ${B \subset V_j}$ with ${|A| \geq \epsilon |V_i|, |B| \geq \epsilon |V_j|}$, where ${d(A,B) := |E \cap (A \times B)|/|A| |B|}$ is the density of edges between ${A}$ and ${B}$.
This lemma becomes useful in the regime when ${n}$ is very large compared to ${k_0}$ or ${1/\epsilon}$, because all the conclusions of the lemma are uniform in ${n}$. Very roughly speaking, it says that “up to errors of size ${\epsilon}$“, a large graph can be more or less described completely by a bounded number of quantities ${d(V_i, V_j)}$. This can be interpreted as saying that the space of all graphs is totally bounded (and hence precompact) in a suitable metric space, thus allowing one to take formal limits of sequences (or subsequences) of graphs; see for instance this paper of Lovasz and Szegedy for a discussion.
For various technical reasons it is easier to work with a slightly weaker version of the lemma, which allows for the cells ${V_1,\ldots,V_k}$ to have unequal sizes:
Lemma 2 (Regularity lemma, weighted version) Let ${G = (V,E)}$ be a graph on ${n}$ vertices, and let ${\epsilon > 0}$. Then there exists a partition of the vertices ${V = V_1 \cup \ldots \cup V_k}$, with ${1 \leq k \leq C(\epsilon)}$ bounded above by a quantity ${C(\epsilon)}$ depending only on ${\epsilon}$, obeying the following properties:
While Lemma 2 is, strictly speaking, weaker than Lemma 1 in that it does not enforce the equitable size property between the atoms, in practice it seems that the two lemmas are roughly of equal utility; most of the combinatorial consequences of Lemma 1 can also be proven using Lemma 2. The point is that one always has to remember to weight each cell ${V_i}$ by its density ${|V_i|/|V|}$, rather than by giving each cell an equal weight as in Lemma 1. Lemma 2 also has the advantage that one can easily generalise the result from finite vertex sets ${V}$ to other probability spaces (for instance, one could weight ${V}$ with something other than the uniform distribution). For applications to hypergraph regularity, it turns out to be slightly more convenient to have two partitions (coarse and fine) rather than just one; see for instance my own paper on this topic. In any event the arguments below that we give to prove Lemma 2 can be modified to give a proof of Lemma 1 also. The proof of the regularity lemma is usually conducted by a greedy algorithm. Very roughly speaking, one starts with the trivial partition of ${V}$. If this partition already regularises the graph, we are done; if not, this means that there are some sets ${A}$ and ${B}$ in which there is a significant density fluctuation beyond what has already been detected by the original partition. One then adds these sets to the partition and iterates the argument. Every time a new density fluctuation is incorporated into the partition that models the original graph, this increases a certain “index” or “energy” of the partition. On the other hand, this energy remains bounded no matter how complex the partition, so eventually one must reach a long “energy plateau” in which no further refinement is possible, at which point one can find the regular partition.
One disadvantage of the greedy algorithm is that it is not efficient in the limit ${n \rightarrow \infty}$, as it requires one to search over all pairs of subsets ${A, B}$ of a given pair ${V_i, V_j}$ of cells, which is an exponentially long search. There are more algorithmically efficient ways to regularise, for instance a polynomial time algorithm was given by Alon, Duke, Lefmann, Rödl, and Yuster. However, one can do even better, if one is willing to (a) allow cells of unequal size, (b) allow a small probability of failure, (c) have the ability to sample vertices from ${G}$ at random, and (d) allow for the cells to be defined “implicitly” (via their relationships with a fixed set of reference vertices) rather than “explicitly” (as a list of vertices). In that case, one can regularise a graph in a number of operations bounded in ${n}$. Indeed, one has
Lemma 3 (Regularity lemma via random neighbourhoods) Let ${\epsilon > 0}$. Then there exists integers ${M_1,\ldots,M_m}$ with the following property: whenever ${G = (V,E)}$ be a graph on finitely many vertices, if one selects one of the integers ${M_r}$ at random from ${M_1,\ldots,M_m}$, then selects ${M_r}$ vertices ${v_1,\ldots,v_{M_r} \in V}$ uniformly from ${V}$ at random, then the ${2^{M_r}}$ vertex cells ${V^{M_r}_1,\ldots,V^{M_r}_{2^{M_r}}}$ (some of which can be empty) generated by the vertex neighbourhoods ${A_t := \{ v \in V: (v,v_t) \in E \}}$ for ${1 \leq t \leq M_r}$, will obey the conclusions of Lemma 2 with probability at least ${1-O(\epsilon)}$.
Thus, roughly speaking, one can regularise a graph simply by taking a large number of random vertex neighbourhoods, and using the partition (or Venn diagram) generated by these neighbourhoods as the partition. The intuition is that if there is any non-uniformity in the graph (e.g. if the graph exhibits bipartite behaviour), this will bias the random neighbourhoods to seek out the partitions that would regularise that non-uniformity (e.g. vertex neighbourhoods would begin to fill out the two vertex cells associated to the bipartite property); if one takes sufficiently many such random neighbourhoods, the probability that all detectable non-uniformity is captured by the partition should converge to ${1}$. (It is more complicated than this, because the finer one makes the partition, the finer the types of non-uniformity one can begin to detect, but this is the basic idea.)
This fact seems to be reasonably well-known folklore, discovered independently by many authors; it is for instance quite close to the graph property testing results of Alon and Shapira, and also appears implicitly in a paper of Ishigami, as well as a paper of Austin (and perhaps even more implicitly in a paper of myself). However, in none of these papers is the above lemma stated explicitly. I was asked about this lemma recently, so I decided to provide a proof here.
I’ve just uploaded to the arXiv my paper “An inverse theorem for the bilinear $L^2$ Strichartz estimate for the wave equation“. This paper is another technical component of my “heatwave project“, which aims to establish the global regularity conjecture for energy-critical wave maps into hyperbolic space. I have been in the process of writing the final paper of that project, in which I will show that the only way singularities can form is if a special type of solution, known as an “almost periodic blowup solution”, exists. However, I recently discovered that the existing function space estimates that I was relying on for the large energy perturbation theory were not quite adequate, and in particular I needed a certain “inverse theorem” for a standard bilinear estimate which was not quite in the literature. The purpose of this paper is to establish that inverse theorem, which may also have some application to other nonlinear wave equations.
In set theory, a function ${f: X \rightarrow Y}$ is defined as an object that evaluates every input ${x}$ to exactly one output ${f(x)}$. However, in various branches of mathematics, it has become convenient to generalise this classical concept of a function to a more abstract one. For instance, in operator algebras, quantum mechanics, or non-commutative geometry, one often replaces commutative algebras of (real or complex-valued) functions on some space ${X}$, such as ${C(X)}$ or ${L^\infty(X)}$, with a more general – and possibly non-commutative – algebra (e.g. a ${C^*}$-algebra or a von Neumann algebra). Elements in this more abstract algebra are no longer definable as functions in the classical sense of assigning a single value ${f(x)}$ to every point ${x \in X}$, but one can still define other operations on these “generalised functions” (e.g. one can multiply or take inner products between two such objects).
Generalisations of functions are also very useful in analysis. In our study of ${L^p}$ spaces, we have already seen one such generalisation, namely the concept of a function defined up to almost everywhere equivalence. Such a function ${f}$ (or more precisely, an equivalence class of classical functions) cannot be evaluated at any given point ${x}$, if that point has measure zero. However, it is still possible to perform algebraic operations on such functions (e.g. multiplying or adding two functions together), and one can also integrate such functions on measurable sets (provided, of course, that the function has some suitable integrability condition). We also know that the ${L^p}$ spaces can usually be described via duality, as the dual space of ${L^{p'}}$ (except in some endpoint cases, namely when ${p=\infty}$, or when ${p=1}$ and the underlying space is not ${\sigma}$-finite).
We have also seen (via the Lebesgue-Radon-Nikodym theorem) that locally integrable functions ${f \in L^1_{\hbox{loc}}({\bf R})}$ on, say, the real line ${{\bf R}}$, can be identified with locally finite absolutely continuous measures ${m_f}$ on the line, by multiplying Lebesgue measure ${m}$ by the function ${f}$. So another way to generalise the concept of a function is to consider arbitrary locally finite Radon measures ${\mu}$ (not necessarily absolutely continuous), such as the Dirac measure ${\delta_0}$. With this concept of “generalised function”, one can still add and subtract two measures ${\mu, \nu}$, and integrate any measure ${\mu}$ against a (bounded) measurable set ${E}$ to obtain a number ${\mu(E)}$, but one cannot evaluate a measure ${\mu}$ (or more precisely, the Radon-Nikodym derivative ${d\mu/dm}$ of that measure) at a single point ${x}$, and one also cannot multiply two measures together to obtain another measure. From the Riesz representation theorem, we also know that the space of (finite) Radon measures can be described via duality, as linear functionals on ${C_c({\bf R})}$.
There is an even larger class of generalised functions that is very useful, particularly in linear PDE, namely the space of distributions, say on a Euclidean space ${{\bf R}^d}$. In contrast to Radon measures ${\mu}$, which can be defined by how they “pair up” against continuous, compactly supported test functions ${f \in C_c({\bf R}^d)}$ to create numbers ${\langle f, \mu \rangle := \int_{{\bf R}^d} f\ d\overline{\mu}}$, a distribution ${\lambda}$ is defined by how it pairs up against a smooth compactly supported function ${f \in C^\infty_c({\bf R}^d)}$ to create a number ${\langle f, \lambda \rangle}$. As the space ${C^\infty_c({\bf R}^d)}$ of smooth compactly supported functions is smaller than (but dense in) the space ${C_c({\bf R}^d)}$ of continuous compactly supported functions (and has a stronger topology), the space of distributions is larger than that of measures. But the space ${C^\infty_c({\bf R}^d)}$ is closed under more operations than ${C_c({\bf R}^d)}$, and in particular is closed under differential operators (with smooth coefficients). Because of this, the space of distributions is similarly closed under such operations; in particular, one can differentiate a distribution and get another distribution, which is something that is not always possible with measures or ${L^p}$ functions. But as measures or functions can be interpreted as distributions, this leads to the notion of a weak derivative for such objects, which makes sense (but only as a distribution) even for functions that are not classically differentiable. Thus the theory of distributions can allow one to rigorously manipulate rough functions “as if” they were smooth, although one must still be careful as some operations on distributions are not well-defined, most notably the operation of multiplying two distributions together. Nevertheless one can use this theory to justify many formal computations involving derivatives, integrals, etc. (including several computations used routinely in physics) that would be difficult to formalise rigorously in a purely classical framework.
If one shrinks the space of distributions slightly, to the space of tempered distributions (which is formed by enlarging dual class ${C^\infty_c({\bf R}^d)}$ to the Schwartz class ${{\mathcal S}({\bf R}^d)}$), then one obtains closure under another important operation, namely the Fourier transform. This allows one to define various Fourier-analytic operations (e.g. pseudodifferential operators) on such distributions.
Of course, at the end of the day, one is usually not all that interested in distributions in their own right, but would like to be able to use them as a tool to study more classical objects, such as smooth functions. Fortunately, one can recover facts about smooth functions from facts about the (far rougher) space of distributions in a number of ways. For instance, if one convolves a distribution with a smooth, compactly supported function, one gets back a smooth function. This is a particularly useful fact in the theory of constant-coefficient linear partial differential equations such as ${Lu=f}$, as it allows one to recover a smooth solution ${u}$ from smooth, compactly supported data ${f}$ by convolving ${f}$ with a specific distribution ${G}$, known as the fundamental solution of ${L}$. We will give some examples of this later in these notes.
It is this unusual and useful combination of both being able to pass from classical functions to generalised functions (e.g. by differentiation) and then back from generalised functions to classical functions (e.g. by convolution) that sets the theory of distributions apart from other competing theories of generalised functions, in particular allowing one to justify many formal calculations in PDE and Fourier analysis rigorously with relatively little additional effort. On the other hand, being defined by linear duality, the theory of distributions becomes somewhat less useful when one moves to more nonlinear problems, such as nonlinear PDE. However, they still serve an important supporting role in such problems as a “ambient space” of functions, inside of which one carves out more useful function spaces, such as Sobolev spaces, which we will discuss in the next set of notes.
From Tim Gowers’ blog comes the announcement that the Tricki – a wiki for various tricks and strategies for proving mathematical results – is now live. (My own articles for the Tricki are also on this blog; also Ben Green has written up an article on using finite fields to prove results about infinite fields which is loosely based on my own post on the topic, which is in turn based on an article of Serre.) It seems to already be growing at a reasonable rate, with many contributors.
Recently, I have been studying the concept of amenability on groups. This concept can be defined in a “combinatorial” or “finitary” fashion, using Følner sequences, and also in a more “functional-analytic” or “infinitary”‘ fashion, using invariant means. I wanted to get some practice passing back and forth between these two definitions, so I wrote down some notes on how to do this, and also how to take some facts about amenability that are usually proven in one setting, and prove them instead in the other. These notes are thus mostly for my own benefit, but I thought I might post them here also, in case anyone else is interested.
The famous Gödel completeness theorem in logic (not to be confused with the even more famous Gödel incompleteness theorem) roughly states the following:
Theorem 1 (Gödel completeness theorem, informal statement) Let ${\Gamma}$ be a first-order theory (a formal language ${{\mathcal L}}$, together with a set of axioms, i.e. sentences assumed to be true), and let ${\phi}$ be a sentence in the formal language. Assume also that the language ${{\mathcal L}}$ has at most countably many symbols. Then the following are equivalent:
• (i) (Syntactic consequence) ${\phi}$ can be deduced from the axioms in ${\Gamma}$ by a finite number of applications of the laws of deduction in first order logic. (This property is abbreviated as ${\Gamma \vdash \phi}$.)
• (ii) (Semantic consequence) Every structure ${{\mathfrak U}}$ which satisfies or models ${\Gamma}$, also satisfies ${\phi}$. (This property is abbreviated as ${\Gamma \models \phi}$.)
• (iii) (Semantic consequence for at most countable models) Every structure ${{\mathfrak U}}$ which is at most countable, and which models ${\Gamma}$, also satisfies ${\phi}$.
One can also formulate versions of the completeness theorem for languages with uncountably many symbols, but I will not do so here. One can also force other cardinalities on the model ${{\mathfrak U}}$ by using the Löwenheim-Skolem theorem.
To state this theorem even more informally, any (first-order) result which is true in all models of a theory, must be logically deducible from that theory, and vice versa. (For instance, any result which is true for all groups, must be deducible from the group axioms; any result which is true for all systems obeying Peano arithmetic, must be deducible from the Peano axioms; and so forth.) In fact, it suffices to check countable and finite models only; for instance, any first-order statement which is true for all finite or countable groups, is in fact true for all groups! Informally, a first-order language with only countably many symbols cannot “detect” whether a given structure is countably or uncountably infinite. Thus for instance even the ZFC axioms of set theory must have some at most countable model, even though one can use ZFC to prove the existence of uncountable sets; this is known as Skolem’s paradox. (To resolve the paradox, one needs to carefully distinguish between an object in a set theory being “externally” countable in the structure that models that theory, and being “internally” countable within that theory.)
Of course, a theory ${\Gamma}$ may contain undecidable statements ${\phi}$ – sentences which are neither provable nor disprovable in the theory. By the completeness theorem, this is equivalent to saying that ${\phi}$ is satisfied by some models of ${\Gamma}$ but not by other models. Thus the completeness theorem is compatible with the incompleteness theorem: recursively enumerable theories such as Peano arithmetic are modeled by the natural numbers ${{\mathbb N}}$, but are also modeled by other structures also, and there are sentences satisfied by ${{\mathbb N}}$ which are not satisfied by other models of Peano arithmetic, and are thus undecidable within that arithmetic.
An important corollary of the completeness theorem is the compactness theorem:
Corollary 2 (Compactness theorem, informal statement) Let ${\Gamma}$ be a first-order theory whose language has at most countably many symbols. Then the following are equivalent:
• (i) ${\Gamma}$ is consistent, i.e. it is not possible to logically deduce a contradiction from the axioms in ${\Gamma}$.
• (ii) ${\Gamma}$ is satisfiable, i.e. there exists a structure ${{\mathfrak U}}$ that models ${\Gamma}$.
• (iii) There exists a structure ${{\mathfrak U}}$ which is at most countable, that models ${\Gamma}$.
• (iv) Every finite subset ${\Gamma'}$ of ${\Gamma}$ is consistent.
• (v) Every finite subset ${\Gamma'}$ of ${\Gamma}$ is satisfiable.
• (vi) Every finite subset ${\Gamma'}$ of ${\Gamma}$ is satisfiable with an at most countable model.
Indeed, the equivalence of (i)-(iii), or (iv)-(vi), follows directly from the completeness theorem, while the equivalence of (i) and (iv) follows from the fact that any logical deduction has finite length and so can involve at most finitely many of the axioms in ${\Gamma}$. (Again, the theorem can be generalised to uncountable languages, but the models become uncountable also.)
There is a consequence of the compactness theorem which more closely resembles the sequential concept of compactness. Given a sequence ${{\mathfrak U}_1, {\mathfrak U}_2, \ldots}$ of structures for ${{\mathcal L}}$, and another structure ${{\mathfrak U}}$ for ${{\mathcal L}}$, let us say that ${{\mathfrak U}_n}$ converges elementarily to ${{\mathfrak U}}$ if every sentence ${\phi}$ which is satisfied by ${{\mathfrak U}}$, is also satisfied by ${{\mathfrak U}_n}$ for sufficiently large ${n}$. (Replacing ${\phi}$ by its negation ${\neg \phi}$, we also see that every sentence that is not satisfied by ${{\mathfrak U}}$, is not satisfied by ${{\mathfrak U}_n}$ for sufficiently large ${n}$.) Note that the limit ${{\mathfrak U}}$ is only unique up to elementary equivalence. Clearly, if each of the ${{\mathfrak U}_n}$ models some theory ${\Gamma}$, then the limit ${{\mathfrak U}}$ will also; thus for instance the elementary limit of a sequence of groups is still a group, the elementary limit of a sequence of rings is still a ring, etc.
Corollary 3 (Sequential compactness theorem) Let ${{\mathcal L}}$ be a language with at most countably many symbols, and let ${{\mathfrak U}_1, {\mathfrak U}_2, \ldots}$ be a sequence of structures for ${{\mathcal L}}$. Then there exists a subsequence ${{\mathfrak U}_{n_j}}$ which converges elementarily to a limit ${{\mathfrak U}}$ which is at most countable.
Proof: For each structure ${{\mathfrak U}_n}$, let ${\hbox{Th}({\mathfrak U}_n)}$ be the theory of that structure, i.e. the set of all sentences that are satisfied by that structure. One can view that theory as a point in ${\{0,1\}^{{\mathcal S}}}$, where ${{\mathcal S}}$ is the set of all sentences in the language ${{\mathcal L}}$. Since ${{\mathcal L}}$ has at most countably many symbols, ${{\mathcal S}}$ is at most countable, and so (by the sequential Tychonoff theorem) ${\{0,1\}^{{\mathcal S}}}$ is sequentially compact in the product topology. (This can also be seen directly by the usual Arzelá-Ascoli diagonalisation argument.) Thus we can find a subsequence ${\hbox{Th}({\mathfrak U}_{n_j})}$ which converges in the product topology to a limit theory ${\Gamma \in \{0,1\}^{{\mathcal S}}}$, thus every sentence in ${\Gamma}$ is satisfied by ${{\mathfrak U}_{n_j}}$ for sufficiently large ${j}$ (and every sentence not in ${\Gamma}$ is not satisfied by ${{\mathfrak U}_{n_j}}$ for sufficiently large ${j}$). In particular, any finite subset of ${\Gamma}$ is satisfiable, hence consistent; by the compactness theorem, ${\Gamma}$ itself is therefore consistent, and has an at most countable model ${{\mathfrak U}}$. Also, each of the theories ${\hbox{Th}({\mathfrak U}_{n_j})}$ is clearly complete (given any sentence ${\phi}$, either ${\phi}$ or ${\neg \phi}$ is in the theory), and so ${\Gamma}$ is complete as well. One concludes that ${\Gamma}$ is the theory of ${{\mathfrak U}}$, and hence ${{\mathfrak U}}$ is the elementary limit of the ${{\mathfrak U}_{n_j}}$ as claimed. $\Box$
[It is also possible to state the compactness theorem using the topological notion of compactness, as follows: let ${X}$ be the space of all structures of a given language ${{\mathcal L}}$, quotiented by elementary equivalence. One can define a topology on ${X}$ by taking the sets ${\{ {\mathfrak U} \in X: {\mathfrak U} \models \phi \}}$ as a sub-base, where ${\phi}$ ranges over all sentences. Then the compactness theorem is equivalent to the assertion that ${X}$ is topologically compact.]
One can use the sequential compactness theorem to build a number of interesting “non-standard” models to various theories. For instance, consider the language ${{\mathcal L}}$ used by Peano arithmetic (which contains the operations ${+, \times}$ and the successor operation ${S}$, the relation ${=}$, and the constant ${0}$), and adjoint a new constant ${N}$ to create an expanded language ${{\mathcal L} \cup \{N\}}$. For each natural number ${n \in {\Bbb N}}$, let ${{\Bbb N}_n}$ be a structure for ${{\mathcal L} \cup \{N\}}$ which consists of the natural numbers ${{\Bbb N}}$ (with the usual interpretations of ${+}$, ${\times}$, etc.) and interprets the symbol ${N}$ as the natural number ${n}$. By the compactness theorem, some subsequence of ${{\Bbb N}_n}$ must converge elementarily to a new structure ${*{\Bbb N}}$ of ${{\mathcal L} \cup \{N\}}$, which still models Peano arithmetic, but now has the additional property that ${N>n}$ for every (standard) natural number ${n}$; thus we have managed to create a non-standard model of Peano arithmetic which contains a non-standardly large number (one which is larger than every standard natural number).
The sequential compactness theorem also lets us construct infinitary limits of various sequences of finitary objects; for instance, one can construct infinite pseudo-finite fields as the elementary limits of sequences of finite fields. I recently discovered that other several correspondence principles between finitary and infinitary objects, such as the Furstenberg correspondence principle between sets of integers and dynamical systems, or the more recent correspondence principles concerning graph limits, can be viewed as special cases of the sequential compactness theorem; it also seems possible to encode much of the sum-product theory in finite fields in an infinitary setting using this theorem. I hope to discuss these points in more detail in a later post. In this post, I wish to review (partly for my own benefit) the proof of the completeness (and hence compactness) theorem. The material here is quite standard (I basically follow the usual proof of Henkin, and taking advantage of Skolemisation), but perhaps the concept of an elementary limit is not as well-known outside of logic as it might be. (The closely related concept of an ultraproduct is better known, and can be used to prove most of the compactness theorem already, thanks to Los’s theorem, but I do not know how to use ultraproducts to ensure that the limiting model is countable. However, one can think (intuitively, at least), of the limit model ${{\mathfrak U}}$ in the above theorem as being the set of “constructible” elements of an ultraproduct of the ${{\mathfrak U}_n}$.)
In order to emphasise the main ideas in the proof, I will gloss over some of the more technical details in the proofs, relying instead on informal arguments and examples at various points.
In these notes we lay out the basic theory of the Fourier transform, which is of course the most fundamental tool in harmonic analysis and also of major importance in related fields (functional analysis, complex analysis, PDE, number theory, additive combinatorics, representation theory, signal processing, etc.). The Fourier transform, in conjunction with the Fourier inversion formula, allows one to take essentially arbitrary (complex-valued) functions on a group ${G}$ (or more generally, a space ${X}$ that ${G}$ acts on, e.g. a homogeneous space ${G/H}$), and decompose them as a (discrete or continuous) superposition of much more symmetric functions on the domain, such as characters ${\chi: G \rightarrow S^1}$; the precise superposition is given by Fourier coefficients ${\hat f(\xi)}$, which take values in some dual object such as the Pontryagin dual ${\hat G}$ of ${G}$. Characters behave in a very simple manner with respect to translation (indeed, they are eigenfunctions of the translation action), and so the Fourier transform tends to simplify any mathematical problem which enjoys a translation invariance symmetry (or an approximation to such a symmetry), and is somehow “linear” (i.e. it interacts nicely with superpositions). In particular, Fourier analytic methods are particularly useful for studying operations such as convolution ${f, g \mapsto f*g}$ and set-theoretic addition ${A, B \mapsto A+B}$, or the closely related problem of counting solutions to additive problems such as ${x = a_1 + a_2 + a_3}$ or ${x = a_1 - a_2}$, where ${a_1, a_2, a_3}$ are constrained to lie in specific sets ${A_1, A_2, A_3}$. The Fourier transform is also a particularly powerful tool for solving constant-coefficient linear ODE and PDE (because of the translation invariance), and can also approximately solve some variable-coefficient (or slightly non-linear) equations if the coefficients vary smoothly enough and the nonlinear terms are sufficiently tame.
The Fourier transform ${\hat f(\xi)}$ also provides an important new way of looking at a function ${f(x)}$, as it highlights the distribution of ${f}$ in frequency space (the domain of the frequency variable ${\xi}$) rather than physical space (the domain of the physical variable ${x}$). A given property of ${f}$ in the physical domain may be transformed to a rather different-looking property of ${\hat f}$ in the frequency domain. For instance:
• Smoothness of ${f}$ in the physical domain corresponds to decay of ${\hat f}$ in the Fourier domain, and conversely. (More generally, fine scale properties of ${f}$ tend to manifest themselves as coarse scale properties of ${\hat f}$, and conversely.)
• Convolution in the physical domain corresponds to pointwise multiplication in the Fourier domain, and conversely.
• Constant coefficient differential operators such as ${d/dx}$ in the physical domain corresponds to multiplication by polynomials such as ${2\pi i \xi}$ in the Fourier domain, and conversely.
• More generally, translation invariant operators in the physical domain correspond to multiplication by symbols in the Fourier domain, and conversely.
• Rescaling in the physical domain by an invertible linear transformation corresponds to an inverse (adjoint) rescaling in the Fourier domain.
• Restriction to a subspace (or subgroup) in the physical domain corresponds to projection to the dual quotient space (or quotient group) in the Fourier domain, and conversely.
• Frequency modulation in the physical domain corresponds to translation in the frequency domain, and conversely.
(We will make these statements more precise below.)
On the other hand, some operations in the physical domain remain essentially unchanged in the Fourier domain. Most importantly, the ${L^2}$ norm (or energy) of a function ${f}$ is the same as that of its Fourier transform, and more generally the inner product ${\langle f, g \rangle}$ of two functions ${f}$ is the same as that of their Fourier transforms. Indeed, the Fourier transform is a unitary operator on ${L^2}$ (a fact which is variously known as the Plancherel theorem or the Parseval identity). This makes it easier to pass back and forth between the physical domain and frequency domain, so that one can combine techniques that are easy to execute in the physical domain with other techniques that are easy to execute in the frequency domain. (In fact, one can combine the physical and frequency domains together into a product domain known as phase space, and there are entire fields of mathematics (e.g. microlocal analysis, geometric quantisation, time-frequency analysis) devoted to performing analysis on these sorts of spaces directly, but this is beyond the scope of this course.)
In these notes, we briefly discuss the general theory of the Fourier transform, but will mainly focus on the two classical domains for Fourier analysis: the torus ${{\Bbb T}^d := ({\bf R}/{\bf Z})^d}$, and the Euclidean space ${{\bf R}^d}$. For these domains one has the advantage of being able to perform very explicit algebraic calculations, involving concrete functions such as plane waves ${x \mapsto e^{2\pi i x \cdot \xi}}$ or Gaussians ${x \mapsto A^{d/2} e^{-\pi A |x|^2}}$.
|
{"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": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 373, "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": 0.9642253518104553, "perplexity": 189.60372331417557}, "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-2021-49/segments/1637964363189.92/warc/CC-MAIN-20211205130619-20211205160619-00042.warc.gz"}
|
https://homework.cpm.org/category/MN/textbook/cc3mn/chapter/3/lesson/3.2.5/problem/3-113
|
### Home > CC3MN > Chapter 3 > Lesson 3.2.5 > Problem3-113
3-113.
Solve each equation.
1. $3(5x+2)=8x+20$
Distribute and simplify each side as much as possible.
Get all variables on one side and all numbers on the other.
$x=2$
1. $−2(x−3)+4x=−(−x+1)$
Follow the steps in part (a).
|
{"extraction_info": {"found_math": true, "script_math_tex": 3, "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": 0, "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": 0.8175721168518066, "perplexity": 4601.467373692151}, "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-2021-49/segments/1637964363216.90/warc/CC-MAIN-20211205191620-20211205221620-00303.warc.gz"}
|
https://physics.stackexchange.com/questions/528144/what-is-a-perfect-fluid-really
|
# What is a “perfect fluid”, really?
In Statistical Mechanics, unless I'm making a confusion mistake, a perfect fluid is defined as a large collection of particles without any "internal" interactions (except maybe from point collisions). Long and short range forces are all neglected. This gives the usual perfect gas law: $$$$\tag{1} p V = N k T.$$$$ Assuming adiabatic irreversibility, this implies the polytrope relation, which is a special case of a barotrope state relation : $$$$\tag{2} p = \kappa \, \rho_{\text{mass}}^{\gamma},$$$$ where $$\kappa$$ is a constant and $$\gamma$$ is the adiabatic index of the fluid. Of course, $$\rho_{\text{mass}}$$ is the proper mass density of the fluid. We could also find $$$$\tag{3} p = (\gamma - 1) \, \rho_{\text{int}},$$$$ where $$\rho_{\text{int}}$$ is the internal energy density, defined as $$\rho_{\text{int}} = \rho - \rho_{\text{mass}}$$ if $$\rho$$ is the total energy density (I'm using natural units so $$c \equiv 1$$).
Now, in Special (and General) Relativity, a perfect fluid is defined as any substance that doesn't show any macroscopic viscosity and shear (this $$\underline{\text{suggest}}$$ no internal microscopic interactions, but this isn't obvious), and such that the energy-momentum of the fluid is diagonal and isotropic in the proper reference frame: $$$$\tag{4} T_{ab} = \begin{bmatrix} \rho & 0 & 0 & 0 \\ 0 & p & 0 & 0 \\ 0 & 0 & p & 0 \\ 0 & 0 & 0 & p \end{bmatrix}.$$$$ Here, a barotropic relation may admit any function $$p(\rho)$$, and not just (2) or (3) above. For example, we may admit the Van der Waals law which isn't a perfect fluid in statistical mechanics (there are some short range forces in action) : $$$$\tag{5} p = \frac{c \, \rho_{\text{mass}} \, T}{1 - a \, \rho_{\text{mass}}} - b \, \rho_{\text{mass}}^2.$$$$ This special relativistic definition isn't the same as the statistical mechanics definition, since it may admit fluids with some internal interactions (yet without showing any macroscopic shear and viscosity).
Now, I'm finding myself irritated by these two definitions, which aren't exactly equivalent. So what really is a "perfect fluid"? The $$\underline{\text{statistical}}$$ one (without any microscopic internal interactions), or the $$\underline{\text{relativistic}}$$ one (which may admit internal interactions)?
Or is there two different "names" that may differentiate the two definitions, something like "ideal fluid" and "perfect fluid" or something else?
I don't like the two inequivalent definitions having the same name, since it opens the door to confusion. I don't want a sloppy use of the same name, just because we are working in different fields (classical statistical mechanicians, or general relativists, or fluid dynamicians, ...).
I have the impression that the statistical definition is the right one, from an historical perspective, and that the relativists should call their perfect fluid as "ideal fluid", instead. Is that right? Or maybe it should be the reverse??
The sloppy Wikipedia appears to reverse the names: https://en.wikipedia.org/wiki/Perfect_fluid, which apparently was written by a relativist! And https://en.wikipedia.org/wiki/Ideal_gas which calls "ideal gas" the perfect fluid of statistical mechanics. Now I'm all confused! Wikipedia isn't a good reference for physics definitions, since there are frequently many inconsistencies.
I think you are not distinguishing properly between ideal/perfect fluids and ideal/perfect gases as they are different concepts:
In traditional fluid mechanics a perfect or ideal fluid is only characterised by the absence of dissipation, the viscosity and the coefficient of heat conduction are zero (Landau & Lafshitz) and the process as a consequence reversible. This means that its equations of motion are given by the Euler equations (including constant entropy) and not the full Navier-Stokes equations that contain a viscous term as well and were written down almost 100 years later in the 1840s. A perfect 'inviscid' fluid can be any fluid, a gas or a liquid, and poses no restrictions regarding the material law. It is particularly useful in aerodynamics where viscous contributions generally only dominate near the walls. Assuming an ideal fluid you may be able to obtain analytical solutions without the need for numerical simulations that take viscous effects directly into account.
An ideal gas on the other hand is a model for the material law: In this case the members of a rarefied gas are assumed as point-particles only interacting in elastic collisions that are assumed to obey Newtonian physics. This means the particles have only translational degrees of freedom and no complex far-field interactions between particles are admitted. If furthermore the heat capacity can be assumed constant, it is considered a perfect gas. In kinetic theory of gases this allows for a simple estimation of transport coefficients and most compressible mechanics are based on this simplification.
• So you're saying that what I called a "perfect fluid" in statistical mechanics is actually a "perfect gas", not a fluid? This would make sense. – Cham Jan 30 '20 at 21:18
• @Cham To be precise, what you describe as perfect fluid in statistical mechanics in the first section of your question would be an ideal gas for most people, including myself. I am not aware of statistical mechanics literature that actually defines it the way you described it. E.g. Landau & Lafshitz, as already mentioned, adhere to the nomenclature I used. – 2b-t Jan 30 '20 at 21:33
• I'm not sure to understand your previous comment. The statistical definition of an ideal gas (what I wrongly called "perfect fluid") is a collection of particles without any internal interaction. It's a bunch of free particles. This is how we derive the formula $p V = N k T$, and so the polytrope formula (2). – Cham Jan 30 '20 at 21:42
• @Cham Yeah, that is correct. I only intended to say that I think you mixed up the perfect fluid and the perfect gas in the first section of your question and the literature (also in statistical mechanics) is to my knowledge consistent in distinguishing the two as different concepts. I have noticed that in scientific papers people do not distinguish cleanly between inviscid flow, perfect/ideal fluid and perfect/ideal gas but books are generally consistent and precise in this regard. – 2b-t Jan 30 '20 at 21:50
• Ok, I think things are getting clearer now, thanks. Yes, many authors are very sloppy in the terms and nomenclature used (like you said), and this is why I got confused in the long run (after reading a lot of papers). It is worst in French (my native language), since we tend to say "gaz parfait" (perfect gas, instead of ideal gas): fr.wikipedia.org/wiki/Gaz_parfait, and "fluide parfait" (perfect fluid): fr.wikipedia.org/wiki/Fluide_parfait, and often mixing the words "gas" and "fluid"! – Cham Jan 30 '20 at 22:08
That Friedman used a perfect fluid is crazy.
Space is not a perfect fluid as it seems infinitely compressible. But it Could also be a fluid with varying viscosity. More viscous at low density, less viscous at high density. This Could account for dark components. High viscosity in low density regions gives illusion of mass/inertia. Low viscosity in dense regions would cause increased micro turbulence which could absorb smooth rotational flow.
|
{"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": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 16, "wp-katex-eq": 0, "align": 0, "equation": 5, "x-ck12": 0, "texerror": 0, "math_score": 0.9472256302833557, "perplexity": 623.1725508967613}, "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-2021-31/segments/1627046153223.30/warc/CC-MAIN-20210727072531-20210727102531-00051.warc.gz"}
|
https://research.snu.edu.in/publication/cp-violation-due-to-compactification
|
X
CP violation due to compactification
C.S. Lim, N. Maru,
Published in
2010
Volume: 81
Issue: 7
Abstract
We address the challenging issue of how CP violation is realized in higher dimensional gauge theories without higher dimensional elementary scalar fields. In such theories interactions are basically governed by a gauge principle and therefore to get CP violating phases is a nontrivial task. It is demonstrated that CP violation is achieved as the result of compactification of extra dimensions, which is incompatible with the 4-dimensional CP transformation. As a simple example we adopt a 6-dimensional U(1) model compactified on a 2-dimensional orbifold T2/Z4. We argue that the 4-dimensional CP transformation is related to the complex structure of the extra space and show how the Z4 orbifolding leads to CP violation. We confirm by explicit calculation of the interaction vertices that CP violating phases remain even after the rephasing of relevant fields. For completeness, we derive a rephasing invariant CP violating quantity, following a similar argument in the Kobayashi-Maskawa model which led to the Jarlskog parameter. As an example of a CP violating observable we briefly comment on the electric dipole moment of the electron. © 2010 The American Physical Society.
About the journal
Published in
Open Access
Impact factor
N/A
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8598341941833496, "perplexity": 1011.9506626572419}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": false}, "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-2022-49/segments/1669446711278.74/warc/CC-MAIN-20221208050236-20221208080236-00874.warc.gz"}
|
https://rdrr.io/cran/EnvStats/man/zTestGevdShape.html
|
# zTestGevdShape: Test Whether the Shape Parameter of a Generalized Extreme... In EnvStats: Package for Environmental Statistics, Including US EPA Guidance
### Description
Estimate the shape parameter of a generalized extreme value distribution and test the null hypothesis that the true value is equal to 0.
### Usage
1 2 zTestGevdShape(x, pwme.method = "unbiased", plot.pos.cons = c(a = 0.35, b = 0), alternative = "two.sided")
### Arguments
x numeric vector of observations. Missing (NA), undefined (NaN), and infinite (Inf, -Inf) values are allowed but will be removed. pwme.method character string specifying the method of estimating the probability-weighted moments. Possible values are "unbiased" (method based on the U-statistic; the default), and "plotting.position" (plotting position). See the help file for egevd for more information on these estimation methods. plot.pos.cons numeric vector of length 2 specifying the constants used in the formula for the plotting positions. The default value is plot.pos.cons=c(a=0.35, b=0). If this vector has a names attribute with the value c("a","b") or c("b","a"), then the elements will be matched by name in the formula for computing the plotting positions. Otherwise, the first element is mapped to the name "a" and the second element to the name "b". See the help file for egevd for more information. This argument is ignored if pwme.method is not equal to "plotting.position". alternative character string indicating the kind of alternative hypothesis. The possible values are "two.sided" (shape not equal to 0; the default), "less" (shape less than 0), and "greater" (shape greater than 0).
### Details
Let \underline{x} = x_1, x_2, …, x_n be a vector of n observations from a generalized extreme value distribution with parameters location=η, scale=θ, and shape=κ. Furthermore, let \hat{κ}_{pwme} denote the probability-weighted moments estimator (PWME) of the shape parameter κ (see the help file for egevd). Then the statistic
z = \frac{\hat{κ}_{pwme}}{√{0.5633/n}} \;\;\;\;\;\; (1)
is asymptotically distributed as a N(0,1) random variable under the null hypothesis H_0: κ = 0 (Hosking et al., 1985). The function zTestGevdShape performs the usual one-sample z-test using the statistic computed in Equation (1). The PWME of κ may be computed using either U-statistic type probability-weighted moments estimators or plotting-position type estimators (see egevd). Although Hosking et al. (1985) base their statistic on plotting-position type estimators, Hosking and Wallis (1995) recommend using the U-statistic type estimators for almost all applications.
This test is only asymptotically correct. Hosking et al. (1985), however, found that the α-level is adequately maintained for samples as small as n = 25.
### Value
A list of class "htest" containing the results of the hypothesis test. See the help file for htest.object for details.
### Note
Two-parameter extreme value distributions (EVD) have been applied extensively since the 1930's to several fields of study, including the distributions of hydrological and meteorological variables, human lifetimes, and strength of materials. The three-parameter generalized extreme value distribution (GEVD) was introduced by Jenkinson (1955) to model annual maximum and minimum values of meteorological events. Since then, it has been used extensively in the hydological and meteorological fields.
The three families of EVDs are all special kinds of GEVDs. When the shape parameter κ = 0, the GEVD reduces to the Type I extreme value (Gumbel) distribution. When κ > 0, the GEVD is the same as the Type II extreme value distribution, and when κ < 0 it is the same as the Type III extreme value distribution.
Hosking et al. (1985) introduced the test used by the function zTestGevdShape to test the null hypothesis H_0: κ = 0. They found this test has power comparable to the modified likelihood-ratio test, which was found by Hosking (1984) to be the best overall test the thirteen tests he considered.
Fill and Stedinger (1995) denote this test the “kappa test” and compare it with the L-Cs test suggested by Chowdhury et al. (1991) and the probability plot correlation coefficient goodness-of-fit test for the Gumbel distribution given by Vogel (1986) (see the sub-section for test="ppcc" under the Details section of the help file for gofTest).
### Author(s)
Steven P. Millard ([email protected])
### References
Chowdhury, J.U., J.R. Stedinger, and L. H. Lu. (1991). Goodness-of-Fit Tests for Regional Generalized Extreme Value Flood Distributions. Water Resources Research 27(7), 1765–1776.
Fill, H.D., and J.R. Stedinger. (1995). L Moment and Probability Plot Correlation Coefficient Goodness-of-Fit Tests for the Gumbel Distribution and Impact of Autocorrelation. Water Resources Research 31(1), 225–229.
Hosking, J.R.M. (1984). Testing Whether the Shape Parameter is Zero in the Generalized Extreme-Value Distribution. Biometrika 71(2), 367–374.
Hosking, J.R.M., and J.R. Wallis (1995). A Comparison of Unbiased and Plotting-Position Estimators of L Moments. Water Resources Research 31(8), 2019–2025.
Hosking, J.R.M., J.R. Wallis, and E.F. Wood. (1985). Estimation of the Generalized Extreme-Value Distribution by the Method of Probability-Weighted Moments. Technometrics 27(3), 251–261.
Jenkinson, A.F. (1955). The Frequency Distribution of the Annual Maximum (or Minimum) of Meteorological Events. Quarterly Journal of the Royal Meteorological Society 81, 158–171.
Vogel, R.M. (1986). The Probability Plot Correlation Coefficient Test for the Normal, Lognormal, and Gumbel Distributional Hypotheses. Water Resources Research 22(4), 587–590. (Correction, Water Resources Research 23(10), 2013, 1987.)
### See Also
GEVD, egevd, EVD, eevd, Goodness-of-Fit Tests, htest.object.
### Examples
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 # Generate 25 observations from a generalized extreme value distribution with # parameters location=2, scale=1, and shape=1, and test the null hypothesis # that the shape parameter is equal to 0. # (Note: the call to set.seed simply allows you to reproduce this example.) set.seed(250) dat <- rgevd(25, location = 2, scale = 1, shape = 1) zTestGevdShape(dat) #Results of Hypothesis Test #-------------------------- # #Null Hypothesis: shape = 0 # #Alternative Hypothesis: True shape is not equal to 0 # #Test Name: Z-test of shape=0 for GEVD # #Estimated Parameter(s): shape = 0.6623014 # #Estimation Method: Unbiased pwme # #Data: dat # #Sample Size: 25 # #Test Statistic: z = 4.412206 # #P-value: 1.023225e-05 #---------- # Clean up #--------- rm(dat)
EnvStats documentation built on May 20, 2017, 12:28 a.m.
Search within the EnvStats package
Search all R packages, documentation and source code
Questions? Problems? Suggestions? Tweet to @rdrrHQ or email at [email protected].
Please suggest features or report bugs in the GitHub issue tracker.
All documentation is copyright its authors; we didn't write any of that.
|
{"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": 0.7705091238021851, "perplexity": 3338.409901661743}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "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-2017-22/segments/1495463607245.69/warc/CC-MAIN-20170523005639-20170523025639-00477.warc.gz"}
|
https://crypto.stackexchange.com/questions/64645/calculate-new-hash-from-old-hash-appended-string
|
# Calculate new hash from old hash + appended string
If I have a hash of some string in the form: hash(UNK + "known"), Is there a way to calculate the hash of (UNK + "known" + "append"), given the hash of the original value?
Basically, I'm asking if the algorithm works by hashing the old hash + new input, or if it only hashes the input by itself.
Thanks!
What you are looking for is called a length extension attack. A length extension attack is, when an attacker given and $$h = H(m)$$ is capable to compute $$h' = H(m\|m')$$ for some $$m'$$ without knowing $$m$$.
Hash functions constructed using the Merkle-Damgård construction are generally susceptible to length extension attacks and SHA512 is not an exception.
The reason is the structure of a Merkle-Damgård hash function, which operates by iterating a compression function $$f : \{0,1\}^{\ell'} \times \{0,1\}^\ell \to \{0,1\}^{\ell'}$$ that maps an $$\ell'$$ bit intermediate hash-value and an $$\ell$$ bit message block to a new $$\ell'$$ bit intermediate hash-value. (For SHA-512, $$\ell=1024$$ and $$\ell'=512$$). Essentially it takes a message $$m$$ that must be a multiple of the block size $$\ell$$, splits it into blocks $$m_1,\dots m_L$$ (for a total message length of $$|m|=L\cdot\ell$$), sets $$h_0 := IV \in \{0,1\}^{\ell'}$$ and for $$1\leq i\leq L$$ computes $$h_i := f(h_{i-1},m_i).$$ Finally it outputs $$h_L$$.
From this description you can easily infer that given $$h=h_L$$ you can choose a new block $$m'$$ and compute $$h_{i+1} = f(h,m') = H(m\|m')$$ giving you a length extension attack.
However, as most things it's not quite that simple. I said above, that $$| m|$$ needs to be a multiple of the block size. This is in general not the case, so some padding needs to take place to bring the message length up to the next multiple of the block length. For SHA-512 the padding works like this:
Let $$m$$ be a message of length $$|m|=b$$ bits. Then we append a single $$1$$ bit and $$k$$ $$0$$ bits, where $$k$$ is the smallest number, such that $$b+1+k+128$$ is a multiple of $$1024$$. Finally $$b$$ encoded as a $$128$$ bit integer is appended. This padded message is then fed into the construction outlined above.
What does this mean for a length extension attack? Mainly two things: First, in addition to $$h_i$$, we also need to know the length $$|m|$$ of the original message to compute the new padding. Second, we will not be able to freely choose $$m'$$.
If we run the length extension attack we will end up with a hash for the message $$m\|1\underbrace{0\dots0}_k\|b\|m',$$ which depending on context may or may not be sufficient for whatever an attacker is trying to do.
|
{"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": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 36, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6057100296020508, "perplexity": 364.5176095242403}, "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-2019-47/segments/1573496665976.26/warc/CC-MAIN-20191113012959-20191113040959-00394.warc.gz"}
|
https://forum.wilmott.com/viewtopic.php?f=15&t=34674&start=45
|
SERVING THE QUANTITATIVE FINANCE COMMUNITY
ppauper
Posts: 70239
Joined: November 15th, 2001, 1:29 pm
Quote10 million female babies aborted in indiaQuoteIndia's 'girl deficit' not poverty problem Study finds selective-sex abortions surprisingly high among educated mothers India's 'girl deficit' deepest among educatedBanned by Indian law for more than a decade, the practice of prenatal selection and selective abortion remains a common practice in India, claiming up to half a million female children each year, according to a recent study by the British medical journal, The Lancet. The use of ultrasound equipment to determine the sex of an unborn child - introduced to India in 1979 - has now spread to every district in the country. The study found it played a crucial role in thetermination of an estimated 10 million female fetuses in the two decades leading up to 1998, and 5 million since 1994, the year the practice was banned. Few doctors in regular clinics offer the service openly, but activists estimate that sex-selection is a $100 million business in India, largely through mobile sex-selection clinics that can drive into almost any village or neighborhood.The practice is common among all religious groups - Hindus, Sikhs, Jains, Muslims, and Christians - but appears to be most common among educated women, a fact that befuddles public health officials and women's rights activists alike."More educated women have more access to technology, they are more privileged, and most educated families have the least number of children," says Sabu George, a researcher with the Center for Women's Development Studies in New Delhi, who did not participate in the study. "This is not just India. Everywhere in the world, smaller families come at the expense of girls."Like China, India has encouraged smaller families through a mixture of financial incentives and campaigns calling for two children at most. Faced with such pressure, many families, rich and poor alike, are turning to prenatal selection to ensure that they receive a son. It's a problem with many potential causes - from social traditions to the economic burden of dowries - but one that could have strong social repercussions for generations to come.The Lancet survey, conducted by Prabhat Jha of St. Michael's Hospital at the University of Toronto and Rajesh Kumar of the Postgraduate Institute of Medical Research in Chandigarh, India, looked at government data collected from a 1998 sample of Indian families in all the districts of the country. From this data, they concluded that 1 out of every 25 female fetuses is aborted, roughly 500,000 per year.Many doctors, including the Indian Medical Association, dispute the findings of the report, saying that the number of female feticides is closer to 250,000 per year. They note that the data sample used by The Lancet study precedes a 2001 Supreme Court decision outlawing the use of ultrasounds to check for girls. But activists note that the law is largely unenforced."If there were half a million feticides a year," S.C. Gulati of the Delhi Institute of Economic Growth told the Indian news channel IBN, "the sex ratio would have been very skewed indeed."Yet the sex ratio is skewed. According to the official Indian Census of 2001, there were 927 girl babies for every 1,000 boy babies, nationwide. The problem is worst in the northwestern states of Haryana, Punjab, Delhi, and Gujarat, where the ratio is less than 900 girls for every 1,000 boys.Against common expectations, female feticide is not a crime of India's backward masses. Instead, it is most common among India's elite, who can afford multiple trips to an ultrasound clinic, and the hushed-up abortion of an unwanted girl. In the prosperous farming district of Kurukshetra, for instance, there are only 770 girl babies for every 1,000 boys. In the high-rent Southwest neighborhoods of New Delhi, the number of girl babies is 845 per 1,000 boys.Some activists say it is wrong to blame Indian society for the incidents of female feticide. The main cause for the "girl deficit," they say, is the arrival of ultrasound technology, and the entrepreneurial spirit of Indian doctors."This is not a cultural thing," says Donna Fernandez, director of Vimochana, a women's rights group based in Bangalore. "This is much more of an economic and political issue. It has got a lot to do with the globalization of technology. It's about the commodification of choices."Cultures don't change overnight, of course, so it's no wonder that activists are focusing attention on regulating the technology that makes feticide possible, the ultrasound. By law, the government can regulate - but not deny - the use of prenatal diagnostic techniques for the purposes of detecting birth defects, but not gender itself. Activists say that while most doctor's offices and clinics have signboards saying that they cannot disclose the gender of a child, it is rare to see a doctor prosecuted if he does so.Karuna Bishnoi, spokeswoman for UNICEF in Delhi, says it shouldn't come as a surprise that educated women are among the most likely to use prenatal sex determination."I personally believe this as a failure of society, not a failure of women," says Ms. Bishnoi. "Women who choose this technique may be victims of discrimination themselves, and they may not be the decisionmakers. Nobody can deny that the status of women is very low in India. There is no quick fix to this."The cultural practice of giving a dowry to the groom's family puts a tremendous financial burden on a bride's family. The cost of not paying a larger dowry can be even higher. In the high-tech city of Bangalore, activists report that it is still common for women to be burned alive by husbands who expected a larger dowry. INDIA'S GIRL DEFICIT A recent study compared the girl-to-boy birth ratios of children born to married Indian women. When it comes to having a second child, a family is somewhat more likely to have a girl if they already have a boy. But second or third children were significantly more likely to be boys if the family did not already have a boy child.SOURCE: THE LANCET; RICH CLABAUGH - STAFF While most of India's religions condemn discrimination against women, there are a few temples in the state of Punjab that promise to help bring fewer women into existence. At the Bir Baba Mandir in Amritsar, couples eat flatbread and onions to ensure a boy child.As a researcher for 20 years on female feticide, conducting field research in the highly educated state of Tamil Nadu, Sabu George says he has some qualms about The Lancet study. In particular, he feels that taking the figures from one year and projecting them backward 20 years just doesn't square with the facts on the ground.But while he believes The Lancet study may have exaggerated the number of female abortions in the past 20 years, it also might underestimate the exponential growth of female feticide into the futures."This is a much larger problem in the future," he says. "Without strong pressure by civil society groups, we'll be seeing 1 million female feticides every year within five years time, definitely."QuoteINDIA'S GIRL DEFICIT A recent study compared the girl-to-boy birth ratios of children born to married Indian women. When it comes to having a second child, a family is somewhat more likely to have a girl if they already have a boy. But second or third children were significantly more likely to be boys if the family did not already have a boy child.SOURCE: THE LANCET; RICH CLABAUGH - STAFF Greenspoon Posts: 56 Joined: February 2nd, 2003, 10:51 pm ### India, a dream becoming reality ppauper, Thanks for this all hot air.....remember the pungent smelling gas that you bulk produce up-north of border from States!!. zeta Posts: 1952 Joined: September 27th, 2005, 3:25 pm ### India, a dream becoming reality Oh I don't know Greenspoon; ppauper does his research and is certainly better than that stupid b**tard Ask Jeeves ppauper Posts: 70239 Joined: November 15th, 2001, 1:29 pm ### India, a dream becoming reality QuoteOriginally posted by: Greenspoonremember the pungent smelling gas that you bulk produce up-north of border from States!!.sour natural gas ? I've made a lot of money on that of late ppauper Posts: 70239 Joined: November 15th, 2001, 1:29 pm ### India, a dream becoming reality QuoteQuote10 million female babies aborted in india judging by the response, I take it this story is the elephant in the room ? cosmologist Posts: 640 Joined: January 24th, 2005, 8:08 am ### India, a dream becoming reality QuoteOriginally posted by: playerI'm going to India and want to set up an account while I'm there....I dont care about forex risk just want an account which I can use...I'm British..By non -resident Indian what exactly do you mean..Born in india or does being of indian decent qualify you??I can offer you a job here as long as you stay. You can open an account. salary account. Then you can hang around for some-time. Bring in some money or ask your guys to transfer that money(wire it). While you are roaming around here , the account stays. If you are living the country, you are supposed to close that account. You just cann't land up as a guest and open an acoount. You are supposed to bring in some FOREX OR you are supposed to use our money as a GUEST.You can use one of our accounts provided you give us on writing that you used it for your money transfer. The b*****ds here have fucked the system to such an extent that Gov is taking note of a 50,000 rs($1000 equivalently) transaction. Lot of black money and a lot of corrupted assholes. 9 out of 10 government guys are corrupt. 8 out of 10 pvt businesses are corrupt. You are a british guy. We don't like british,americans,europeans,russians,chinese,japanese,lebanese, all the middle -east people ,and most other people. We like jews and red-indians. BUT, we like your money. It has a good color and better taste.I am wondering what takes you there. I think you are british and indian by birth. As long as you don't qualify as a citizen here,you cann't open an account. Yes, do a job and have a salary account.I know a guy who works for a broking firm but goes to London once in a year to claim some benefits. I am aghast at his shamelessness. He was born there when his father was working as a coolie in some dark colonies of the queen, I think. Hey can someone check that for me!!!!!!!!!!!!!!!!. What is the rule for claiming the benefits?You are welcome,anyways.cheers
Last edited by cosmologist on January 13th, 2006, 11:00 pm, edited 1 time in total.
cosmologist
Posts: 640
Joined: January 24th, 2005, 8:08 am
### India, a dream becoming reality
I wrote something about the killing of girl-child in India. If someone is interested, please pm me. I am a little worried to put the stuff here as of now. I am afraid of being sued.cheers Pedro- This obsession of yours with Luxembourg is a little too much. Anyways, can you tell me how to get a job there. may be I can go and have an experience, first-hand.
Last edited by cosmologist on January 13th, 2006, 11:00 pm, edited 1 time in total.
ppauper
Posts: 70239
Joined: November 15th, 2001, 1:29 pm
### India, a dream becoming reality
QuoteOriginally posted by: cosmologistI wrote something about the killing of girl-child in India. If someone is interested, please pm me. I am a little worried to put the stuff here as of now. I am afraid of being suedI'm glad someone here cares about the issue.
NamelessWonder
Posts: 170
Joined: June 27th, 2005, 7:31 pm
### India, a dream becoming reality
ppauper, you have probably quoted the entire internet on wilmott in your long and illustrious stay. Dont get me wrong, there is some useful stuff there. However your own opinion is curiously absent in this quotathon. Now that would be interesting to hear.
ppauper
Posts: 70239
Joined: November 15th, 2001, 1:29 pm
### India, a dream becoming reality
QuoteOriginally posted by: NamelessWonderHowever your own opinion is curiously absent let me help you out here.I don't think killing 10 million babies just because they're female is a good thing
cosmologist
Posts: 640
Joined: January 24th, 2005, 8:08 am
### India, a dream becoming reality
QuoteOriginally posted by: ppauperQuoteOriginally posted by: NamelessWonderHowever your own opinion is curiously absent let me help you out here.I don't think killing 10 million babies just because they're female is a good thingGreenspoon is Indian.(His profile). Namelesswonder,I am not sure. But then Indians out here on WILMOTT should BEHAVE like WORLD citizens.The beauty of this forum is that we expect everyone here to be intelligent,impartial,accurate,and incisive. Opinions should fly,not accusations. Where is the big deal in hanging your head in shame for 30 seconds,Mr. Greenspoon? 10 million lives and on top of that unarmed,innocent babies. BLOODY BARBARIANS, aren't they the most despicable human beings(those who killed the babies),baring a soft thought for the poorest of the poors who killed to avoid dowry(in India,the girl's family forks out money as dowry to be given to the groom so that the groom can feed himself well to fuck the girl and if necessary beat her. dowry can go up to millions of rupees/dollars. MITTAL might have given ten millions to his son-in-law ,may be I am guessing). Where is the point in being ridiculed by the world while trying to hide something which everybody knows. Greed,jealousy are two prime factors that have driven most of the Indians. Is there anyone who can dare to prove me wrong. The most corrupted nation,India,may be China is the first. Then India. But,both are like brothers. Everybody knows this. Where is the point in trying to deny it?Cheers
NamelessWonder
Posts: 170
Joined: June 27th, 2005, 7:31 pm
### India, a dream becoming reality
Cosmologist, I am sure you think you are being objective and honest. Good for you. Knock yourself out.The thread started out with an opinion that India has a good economic future. Some discussion on the causes followed. All fine. Some sidetracking of the issue happens. Then ppauper brings in this female foeticide issue. Everybody here will agree that its a bad thing. There is no argument nor denial. But i dont really see how it is the most important point for this discussion. Many people here seem to want to get into a discussion about which is the best country/race and each one will come out with his/her own metric for measuring this supposed superiority. Is this really worthwhile? Every nation/race has its +/- points. India is not exception. Her "crimes" may seem too egregious by today's standards. But not all her citizens are "bad" (or "good"). If you like to slot things into convenient categories, I fear you are seeing things in black and white.And if you do come to the conclusion that India/Iraq/<your favourite target here> is all "bad" what do you propose? Destroy the country for the greater "good" of the world?So my point is that such arguments will not go anywhere. And perhaps Greenspoon's moniker of "hot air" may actually fit. A more interesting and extremely difficult question is how does one solve such social problems? I dont necessarily have answers, but surely this makes for a more intellectually challenging discussion.cheers
Last edited by NamelessWonder on January 16th, 2006, 11:00 pm, edited 1 time in total.
zeta
Posts: 1952
Joined: September 27th, 2005, 3:25 pm
### India, a dream becoming reality
why do people keep on saying cheers. is it a sarcastic cheers? are you in a bar? I just don't get it. I'm all for hearing some solutions to social problems NW, but unless people are willing to act on it,what's the point? Actions speak louder than words. Who is willing to act? ED: who is able to act?
Last edited by zeta on January 16th, 2006, 11:00 pm, edited 1 time in total.
NamelessWonder
Posts: 170
Joined: June 27th, 2005, 7:31 pm
### India, a dream becoming reality
QuoteOriginally posted by: zetawhy do people keep on saying cheers. is it a sarcastic cheers? are you in a bar? I just don't get it. I'm all for hearing some solutions to social problems NW, but unless people are willing to act on it,what's the point? Actions speak louder than words. Who is willing to act? ED: who is able to act?Sure, all discussion on online fora is usually nothing but intellectual masturbation. But then that is the purpose of the off-topic forum. I am sure you are not naive enough to believe that you can change the world by discussing it on the wilmott off-topic forum.Saying cheers is just a mannerism for me. If you are offended by it thats too bad. cheers!
zeta
Posts: 1952
Joined: September 27th, 2005, 3:25 pm
### India, a dream becoming reality
you couldn't possibly offend me, I'm several lines of ascii text on a screen
Wilmott.com has been "Serving the Quantitative Finance Community" since 2001. Continued...
JOBS BOARD
Looking for a quant job, risk, algo trading,...? Browse jobs here...
GZIP: On
|
{"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": 0, "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": 0.274577796459198, "perplexity": 3970.9156773339546}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "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-2019-39/segments/1568514574588.96/warc/CC-MAIN-20190921170434-20190921192434-00556.warc.gz"}
|
http://www.albany.edu/~hammond/demos/Html5/arXiv/lxmlexamples.html
|
HTML Math Examples from arXiv via LaTeXML
Introduction
“arXiv” is the large e-print archive founded by Paul Ginsparg located at Cornell University (originally at Los Alamos National Laboratory). “LaTeXML” is the software for conversion of well-structured LaTeX to HTML originated by Bruce Miller of the U.S. National Institute of Standards and Technology (NIST).
For most of the e-prints at arXiv there is TeX source available, which is often LaTeX source. In the case where an author has provided carefully structured LaTeX source there is the possibility of conversion to HTML using a translation tool with support for math such as LaTeXML.
The relatively recent arrival of HTML, version 5, and the web-served software provided by MathJax, make it possible for ordinary HTML web pages with math to be viewed in most current major web browsers.
Examples
These examples were selected based on my personal mathematical interests and based on the technical consideration that each LaTeX source file lent itself reasonably well to automatic translation. The mathematical merit of these examples has not been reviewed.
Be aware that MathJax can take some time. For example, depending on your platform, the example by Funke & Millson, which represents about 35 pages printed on letter-sized paper and has nearly 2000 math zones, might take 2–5 minutes to load fully. The alternative versions labeled “for Firefox with mathfonts” are for any web browser capable of directly rendering XHTML with MathML; they may also take a while to load but should be quicker than the MathJax-ed versions.
alg-geom/9304003: D. Bayer & D. Mumford,
“What Can Be Computed in Algebraic Geometry”
(or the version for Firefox with mathfonts).
1104.2804: T. Ohira & H. Watanabe,
“A Conjecture on the Collatz-Kakutani Path Length for the Mersenne Primes”
(or the version for Firefox with mathfonts).
1108.5305: J. Funke & J. Millson,
“The Geometric Theta Correspondence for Hilbert Modular Surfaces”
(or the version for Firefox with mathfonts).
1109.1881: Th. Bauer, B. Harbourne, A. L. Knutsen, A. Küronya, S. Müller-Stach, T. Szemberg,
“Negative curves on algebraic surfaces”
(or the version for Firefox with mathfonts).
1207.5765: Joseph H. Silverman,
“An oft cited letter from Tate to Serre on computing local heights on elliptic curves”
(or the version for Firefox with mathfonts).
The idea that LaTeX documents, as they have been found in circulation during the period 1985–2014, could be translated to a formally structured SGML document type is, in a certain sense, folly just as it has been folly to imagine that more than 5% of the HTML documents in circulation during the period 1995–2014 are formally correct. Beyond that, the problem in translating LaTeX is compounded by the fact that the principal LaTeX engine implements LaTeX, the language, as a macro package under TeX, which is a Turing-complete programming language. So far in the development of LaTeX, there has been no reliably enforced boundary between LaTeX and TeX. In view of all of this it is remarkable, even astounding, that there has been any substantial degree of success with translation projects such as LaTeXML.
Many examples found at arXiv are not easily made to run through LaTeXML. In fact, there was a large effort mounted by the arXMLiv Project to translate most of the LaTeX source documents at arXiv to HTML using LaTeXML. I understand the success rate as of March 2014 to be around 70%. While that is not sufficient for a fully automated production system, it is nonetheless astounding. Moreover, the problem, as explained above, largely lies with source documents failing to match the standard.
I continue to believe that steps taken by the community toward formalizing suitable profiled usage of LaTeX would go a long way toward making better online versions of mathematical documents easily available. For more on this see my talk at TUG 2010 on LaTeX Profiles
A suitable command line invocation of LaTeXML will lead to HTML, version 5, output that is configured for MathJax. I found it convenient (in Linux, OSX, or Windows with Cygwin) to use a small (Bourne) shell script, which was this:
#!/bin/sh
pname=basename $0 if [ "$#" != "1" ] ; then
echo "Usage: ${pname} stem-name" exit 1 fi stem="$1"
if [ ! $$-f "{stem}.tex"$$ ] ; then
echo "${pname}: Cannot find${stem}.tex"
exit 2
fi
latexml "--destination=${stem}.xml" "${stem}.tex"
if [ "$?" != "0" ] ; then echo "${pname}: latexml did not finish cleanly on ${stem}.tex" exit 3 fi if [ ! $$-f "{stem}.xml"$$ ] ; then echo "${pname}: Cannot find latexml output file ${stem}.xml" exit 4 fi latexmlpost --format=html5 "--destination=${stem}.html" --presentationmathml "${stem}.xml" if [ "$?" != "0" ] ; then
echo "${pname}: latexmlpost did not finish cleanly on${stem}.xml"
fi
|
{"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": 1, "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": 0.8029248118400574, "perplexity": 2905.950112054087}, "config": {"markdown_headings": false, "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-2014-49/segments/1416931007510.17/warc/CC-MAIN-20141125155647-00155-ip-10-235-23-156.ec2.internal.warc.gz"}
|
http://en.wikipedia.org/wiki/Rodrigues'_rotation_formula
|
# Rodrigues' rotation formula
In the theory of three-dimensional rotation, Rodrigues' rotation formula (named after Olinde Rodrigues) is an efficient algorithm for rotating a vector in space, given an axis and angle of rotation. By extension, this can be used to transform all three basis vectors to compute a rotation matrix from an axis–angle representation. In other words, the Rodrigues formula provides an algorithm to compute the exponential map from so(3) to SO(3) without computing the full matrix exponent.
If v is a vector in ℝ3 and k is a unit vector describing an axis of rotation about which v rotates by an angle θ according to the right hand rule, the Rodrigues formula is
$\mathbf{v}_\mathrm{rot} = \mathbf{v} \cos\theta + (\mathbf{k} \times \mathbf{v})\sin\theta + \mathbf{k} (\mathbf{k} \cdot \mathbf{v}) (1 - \cos\theta)~.$
## Derivation
Rodrigues' rotation formula rotates v by an angle θ around an axis z by decomposing it into its components parallel and perpendicular to z, and rotating only the perpendicular component.
Given a rotation axis represented by a unit vector $\mathbf{k}$ and a vector $\mathbf{v}$ that we wish to rotate about $\mathbf{k}$ by the angle $\theta$,
$\mathbf{v}_{\parallel} = (\mathbf{k} \cdot \mathbf{v}) \mathbf{k}$
is the component of $\mathbf{v}$ parallel to $\mathbf{k}$, also called the vector projection of $\mathbf{v}$ on $\mathbf{k}$, and
$\mathbf{v}_{\perp} = \mathbf{v} - \mathbf{v}_{\parallel} = \mathbf{v} - (\mathbf{k} \cdot \mathbf{v}) \mathbf{k}$
is the component of $\mathbf{v}$ orthogonal to $\mathbf{k}$, also called the vector rejection of $\mathbf{v}$ from $\mathbf{k}$.
Let
$\mathbf{w} = \mathbf{k}\times\mathbf{v}$.
The vectors $\mathbf{v}_\perp$ and $\mathbf{w}$ have the same length, but $\mathbf{w}$ is perpendicular to both $\mathbf{k}$ and $\mathbf{v}_\perp$. This can be shown via
$\mathbf{w} = \mathbf{k} \times \mathbf{v} = \mathbf{k} \times (\mathbf{v}_{\parallel} + \mathbf{v}_{\perp}) = \mathbf{k} \times \mathbf{v}_{\parallel} + \mathbf{k} \times \mathbf{v}_{\perp} = \mathbf{k} \times \mathbf{v}_{\perp} ,$
since $\mathbf{k}$ has unit length, is parallel to $\mathbf{v}_\parallel$ and is perpendicular to $\mathbf{v}_\perp$.
The vector $\mathbf{w}$ can be viewed as a copy of $\mathbf{v}_\perp$ rotated by 90° about $\mathbf{k}$. Using trigonometry, we can now rotate $\mathbf{v}_\perp$ by $\theta$ around $\mathbf{k}$ to obtain $\mathbf{v}_{\perp\ \mathrm{rot}}$. Thus,
\begin{align} \mathbf{v}_{\perp\ \mathrm{rot}} &= \mathbf{v}_{\perp}\cos\theta + \mathbf{w}\sin\theta\\ &= (\mathbf{v} - (\mathbf{k} \cdot \mathbf{v}) \mathbf{k})\cos\theta + (\mathbf{k} \times \mathbf{v})\sin\theta. \end{align}
$\mathbf{v}_{\perp\ \mathrm{rot}}$ is also the rejection from $\mathbf{k}$ of the vector $\mathbf{v}_{\mathrm{rot}}$, defined as the desired vector, $\mathbf{v}$ rotated about $\mathbf{k}$ by the angle $\theta$. Since v is not affected by a rotation about $\mathbf{k}$, the projection of $\mathbf{v}_\mathrm{rot}$ on $\mathbf{k}$ coincides with $\mathbf{v}_\parallel$. Thus,
\begin{align} \mathbf{v}_{\mathrm{rot}} &= \mathbf{v}_{\perp\ \mathrm{rot}} + \mathbf{v}_{\parallel\ \mathrm{rot}} \\ &= \mathbf{v}_{\perp\ \mathrm{rot}} + \mathbf{v}_{\parallel} \\ &= (\mathbf{v} - (\mathbf{k} \cdot \mathbf{v}) \mathbf{k}) \cos\theta + (\mathbf{k} \times \mathbf{v})\sin\theta + (\mathbf{k} \cdot \mathbf{v}) \mathbf{k} \\ &= \mathbf{v} \cos\theta + (\mathbf{k} \times \mathbf{v})\sin\theta + \mathbf{k} (\mathbf{k} \cdot \mathbf{v}) (1 - \cos\theta), \end{align}
as required.
### Matrix notation
We first represent v and k as column matrices, and defining a matrix K as the "cross-product matrix" for the vector k, i.e.,
$\mathbf{K}= \left[\begin{array}{ccc} 0 & -k_3 & k_2 \\ k_3 & 0 & -k_1 \\ -k_2 & k_1 & 0 \end{array}\right]$.
This can easily be checked to have the property that
$\mathbf{K}\mathbf{v} = \mathbf{k}\times\mathbf{v}$
for any vector v (in fact, K is the unique matrix with this property).
Now, from the last equation in the previous sub-section, we may write
\begin{align} \mathbf{v}_{\mathrm{rot}} &= \mathbf{v} \cos\theta + (\mathbf{k} \times \mathbf{v})\sin\theta + \mathbf{k} (\mathbf{k} \cdot \mathbf{v}) (1 - \cos\theta) \\ &= \mathbf{v} + (\mathbf{K} \mathbf{v})\sin\theta + (\mathbf{k} (\mathbf{k} \cdot \mathbf{v}) - \mathbf{v}) (1 - \cos\theta). \end{align}
To simplify further, use the well-known formula for the vector triple product,
$\mathbf{a}\times (\mathbf{b}\times \mathbf{c}) = \mathbf{b}(\mathbf{a}\cdot\mathbf{c}) - \mathbf{c}(\mathbf{a}\cdot\mathbf{b})$
with a = b = k, and c = v, to obtain
$(\mathbf{k} (\mathbf{k} \cdot \mathbf{v}) - \mathbf{v}) = \mathbf{k} \times (\mathbf{k} \times \mathbf{v})$
or
$\mathbf{k} (\mathbf{k} \cdot \mathbf{v}) - \mathbf{v} = \mathbf{K}^2 \mathbf{v}$.
This means (substituting the above equation in the last one for vrot) ,
$\mathbf{v}_{\mathrm{rot}} = \mathbf{v} + (\sin\theta) \mathbf{K}\mathbf{v} + (1-\cos\theta)\mathbf{K}^2\mathbf{v}$,
resulting in the Rodrigues' rotation formula in matrix notation,
\begin{align} \mathbf{v}_{\mathrm{rot}} &= \mathbf{R}\mathbf{v} \end{align}
where R is the rotation matrix
\begin{align} \mathbf{R} = \mathbf{I} + (\sin\theta) \mathbf{K} + (1-\cos\theta)\mathbf{K}^2 \end{align}
Since K is defined in terms of the components of the rotation axis k, and θ is the rotation angle, R is the rotation matrix about k by angle θ, and is easy to compute.
R is a member of the rotation group SO(3) of ℝ3, and K is a member of the Lie algebra so(3) of that Lie group. In terms of the matrix exponential, we have
$\mathbf{R} = \mathbf{exp}(\theta\mathbf{K})$.
For an alternative derivation based on this exponential relationship, see Axis–angle representation#Exponential map from so(3) to SO(3). For the inverse mapping, see Axis–angle representation#Log map from SO(3) to so(3).
## References
• Don Koks, (2006) Explorations in Mathematical Physics, Springer Science+Business Media,LLC. ISBN 0-387-30943-8. Ch.4, pps 147 et seq. A Roundabout Route to Geometric Algebra'
|
{"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": 0, "img_math": 54, "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": 0.9996390342712402, "perplexity": 768.4747625749511}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "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-2014-49/segments/1416931005387.19/warc/CC-MAIN-20141125155645-00230-ip-10-235-23-156.ec2.internal.warc.gz"}
|
https://electrical.codidact.com/posts/283170
|
Q&A
# 2 bit subtractor using full subtractor
+2
−1
Can we make a n-bit subtractor using full subtractors or if we want do subtract one binary from another we must use full adders and use the complement of the 2nd number to do the subtraction?
I have only found examples which we use the complement of the second number and using full adders if it is possible to create a n-bit substractor using only full subtractors and without any adders or complements i would really appreciate it if he/she posted the circuit because i am stuck.
Why does this post require moderator attention?
Why should this post be closed?
+3
−0
We don't just give direct answers to homework (or homework-like) questions here, but can help you work thru the problem on your own.
You might consider trying to synthesize a subtractor from scratch, just like you would an adder. The fundamental building block of an adder is the half-adder. It takes in two bits to add, and produces the sum and carry bits. Since there are only 4 possible combinations of inputs, a truth table nicely describes its operation exhaustively:
In1 In2 Sum Car
--- --- --- ---
0 0 0 0
0 1 1 0
1 0 1 0
1 1 0 1
That should be enough to create a circuit of basic logic gates to implement the half-adder. You then chain together two of these per bit to make the full adder. This process is well documented in many place out there, very likely in your textbook too.
Now consider doing the same thing for subtraction. You have two input bits, and two output bits. In this case the output bits are the difference and the borrow.
When you get done with this, it might be instructive to compare that result to constructing a subtractor by complementing one of the input numbers, adding it to the other input number, and adding 1 to the result. Note that adding 1 to the result is the same as if the carry input to the first bit were 1.
I know how to make a full subtractor i just dont know how to connect multiple of them in order to make subtraction of 2 binary numbers with more than 1 bit
That makes little sense. If you really had a full subtractor, then you'd know what the input and output signals were, and then it would be obvious how to chain them to subtract wide numbers.
A full subtractor has three inputs and two outputs. The inputs are the two data bits to subtract, and the borrow input. The outputs are the resulting difference bit and the borrow output. You really should be able to figure out how to chain such blocks to subtract multi-bit numbers.
I cant understand which pins to connect with which pins.
Pins of what exactly? What exactly do you think the pins of this thing are?
Again, we are not here to do your homework for you. You have to put in some effort and be trying to learn. Show a block diagram of this thing, its input and output signals, and explain what you think each of these signals do. You may realize how to hook it up in the process of trying to explain it. Or, if there is a misconception, we'll know better how to help you understand it.
This is getting away from the original question. Instead of adding this to your existing question (and thereby causing confusion), it is probably better to show the diagram, input and output signals, and ask about connecting up the block in a separate question.
Why does this post require moderator attention?
|
{"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": 0.5534964203834534, "perplexity": 516.7926424203022}, "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-2021-49/segments/1637964363134.25/warc/CC-MAIN-20211205005314-20211205035314-00608.warc.gz"}
|
https://embed.planetcalc.com/9134/
|
# A2Z52 encoder/decoder
A2Z52 is a very simple direct substitution cipher, where each alphabet letter is replaced by its number in the alphabet.
Below is the A2Z52 encoder/decoder. A2Z52 is a simple clone of the A1Z26 substitution cipher, where each number is doubled. Thus it contains only even numbers.
Here all letters are set to lowercase, the English alphabet is used, and all non-alphabet symbols are not transformed. In decoding, all numbers (even numbers from 2 to 52) should be separated by any non-digit symbol (dash, space).
#### A2Z52 encoder/decoder
Transformed text
URL copied to clipboard
#### Similar calculators
PLANETCALC, A2Z52 encoder/decoder
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8498913049697876, "perplexity": 5357.245793059539}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "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-2022-27/segments/1656104597905.85/warc/CC-MAIN-20220705174927-20220705204927-00556.warc.gz"}
|
https://brilliant.org/discussions/thread/similar-figures/
|
# Similar Figures
Learn about Similar Figures, geometric figures that can be obtained from each other through a process of expansion or contraction, possibly followed by translation, rotation or reflection.
Note by Calvin Lin
5 years, 2 months ago
MarkdownAppears as
*italics* or _italics_ italics
**bold** or __bold__ bold
- bulleted- list
• bulleted
• list
1. numbered2. list
1. numbered
2. list
Note: you must add a full line of space before and after lists for them to show up correctly
paragraph 1paragraph 2
paragraph 1
paragraph 2
[example link](https://brilliant.org)example link
> This is a quote
This is a quote
# I indented these lines
# 4 spaces, and now they show
# up as a code block.
print "hello world"
# I indented these lines
# 4 spaces, and now they show
# up as a code block.
print "hello world"
MathAppears as
Remember to wrap math in $$...$$ or $...$ to ensure proper formatting.
2 \times 3 $$2 \times 3$$
2^{34} $$2^{34}$$
a_{i-1} $$a_{i-1}$$
\frac{2}{3} $$\frac{2}{3}$$
\sqrt{2} $$\sqrt{2}$$
\sum_{i=1}^3 $$\sum_{i=1}^3$$
\sin \theta $$\sin \theta$$
\boxed{123} $$\boxed{123}$$
Sort by:
you just have to give me a nice poem, that make me relax, thank a lot Sir
- 5 years, 2 months ago
- 5 years, 2 months ago
you got a lot vote down
- 5 years, 2 months ago
Well, that was lame.
- 5 years, 2 months ago
|
{"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": 1, "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": 0.998801052570343, "perplexity": 15296.791078712362}, "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-2018-34/segments/1534221217970.87/warc/CC-MAIN-20180821053629-20180821073629-00289.warc.gz"}
|
https://indico.cern.ch/event/469963/contributions/2269478/
|
# TeV Particle Astrophysics 2016
12-16 September 2016
CERN
Europe/Zurich timezone
There is a live webcast for this event.
## MAGIC observations of the enigmatic Gamma Cygni supernova remnant
15 Sep 2016, 17:45
15m
13/2-005 (CERN)
### 13/2-005
#### CERN
15
Show room on map
Oral Contributions Gamma-ray astrophysics
### Speaker
Mr Marcel Strzys (Max Planck Institute for Physics, Germany)
### Description
Gamma Cygni SNR (G78.2+2.1) is one of the first supernova remnants (SNR) detected in the high-energy gamma-ray band. It is a middle-aged SNR (~7000 years old) situated in the Cygnus region. The high-energy observations by VERITAS and Fermi-LAT revealed a complex, energy-dependent morphology of the SNR in the GeV-TeV band, different from that observed in X-rays. G78.2+2.1 also hosts the pulsar PSR J2021+4026, which is the only variable gamma-ray pulsar known to date.
Here we present the results from recent MAGIC observations of the Gamma Cygni nebula and pulsar complex. We discuss the TeV morphology of the source and possible origins of the gamma-ray emission in the multi-wavelength context.
### Primary author
Mr Marcel Strzys (Max Planck Institute for Physics, Germany)
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9037582278251648, "perplexity": 17370.78662803283}, "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-2021-21/segments/1620243989756.81/warc/CC-MAIN-20210518063944-20210518093944-00066.warc.gz"}
|
https://www.jiskha.com/questions/492240/The-question-that-have-is-to-simplify-and-write-the-answer-in-exponential-notation
|
# math
The question that have is to simplify and write the answer in exponential notation using positive exponents 2 to 4th power x 2 -2
These are my choices
a 4 to the 8th power
b 2 to the 8th power
c 4 to the 2nd power
d 2 to the 2nd power
1. 👍 0
2. 👎 0
3. 👁 81
2 to 4th power x 2 -2 ?
2^4 * 2^(-2)
If so,
2^4 = 16
2^(-2) = 1/(2^2) = 1/4
2^4 * 2^(-2) = 16 * 1/4 = 16/4 = 4
4 = 2^2
1. 👍 0
2. 👎 0
posted by helper
## Similar Questions
1. ### MTH 156
2^6 * 2^7 multiply and simplify and then write the answer in exponential notation. I know the answer is 8,192 but I cannot figure out how to write that in exponential notation. Thanks for the help.
asked by Bella on August 5, 2015
2. ### Chemistry
1. Write 86,400 s in exponential notation. My answer: 8.6400 x 10^4 s 2. Write 0.15 ns using exponential notation with units of s. My answer: 0.15 x 10^-9 3. 141000 g =? kg My answer: 141 kg 4. Write 1.4 Mg using exponential
asked by Anonymous on September 28, 2015
3. ### MTH 156
2^6 * 2^7 multiply and simplify and then write the answer in exponential notation. Thanks!
asked by Bella on August 5, 2015
4. ### Mathematics
How do I do these? 1. Simplify using only positive exponents: (2t)⁻⁶ 2. Simplify using only positive exponents: (w⁻²j⁻⁴)⁻³(j⁷j³) 3. Simplify using only positive exponents: a²b⁻⁷c⁴ ---------- a⁵b³c⁻²
asked by Name on March 11, 2018
5. ### Algebra
Can you please check my work? You have helped other students I know. Thank you:) Multiply -7(2a2 -4) = -14a2 + 28 Multiply 0.5(a + b -5) = 0.5a + 0.5b - 2.5 Factor bx - by + bz = b(x - y + z) Combine like terms (simplify) 12x + 4
asked by Sharon (ms. Sue) on November 8, 2011
6. ### Algebra (check my answers)
Please check these answers. Multiply -7(2a2 -4) = -14a2 + 28 Multiply 0.5(a + b -5) = 0.5a + 0.5b - 2.5 Factor bx - by + bz = b(x - y + z) Combine like terms (simplify) 12x + 4 - 11y - 6x - 9 - y = 6x - 12y - 5 Evaluate the
asked by Sharon on November 8, 2011
7. ### Algebra 1
Plz help me with the following problems. Simplify. 5^-1(3^-2) Simplify. mn^-4/p^0q^-2 Write a scientific notation. 0.0042 Write in standard notation. 6.12*10^3 Simplify. Write in scientific notation. 0.5(8 * 10^5) Simplify. Write
asked by Gabby on February 5, 2014
8. ### math
Could someone please how this problem should be solved? Simplify and write the answer in exponential notation using positive exponents. 2 to the 4th x 2 -2nd power
asked by Dennis on February 6, 2011
9. ### Math
Use the expression 12*12 to answer the question below A. Write the expression using exponential notation B. What is the base? C. What is the exponent? D. WRite the expression in expanded form. C?
asked by §eth on September 4, 2012
10. ### Algebra 2
Exponential Notation Simplify. (-2)^0-(-2)^3-(-2)^-1+(-2)^4-(-2)^-2 I tried solving this problem a few times and kept getting random answers. The answer in the book says that it is 25 1/4 I do not understand how you get that
asked by Ann on September 11, 2011
More Similar Questions
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9086999297142029, "perplexity": 3870.4191492605514}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "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-2019-09/segments/1550247480472.38/warc/CC-MAIN-20190216125709-20190216151709-00341.warc.gz"}
|
https://www.physicsforums.com/threads/gyroscopic-precession.19096/
|
# Homework Help: Gyroscopic precession
1. Apr 12, 2004
### cucumber
hi. not sure if this belongs in here, so sorry in advance for any trouble caused.
i am in a bit of a predicament with a physics assessment of mine; i need to know the mathematical relationships between the precessional frequency, the couple (or torque, as i have read it called) and the angular momentum of a gyroscope, and (here comes the tricky bit) i would like to understand it...
i just need someone to point me in the right direction, i mean i hardly know which questions to ask or where to start looking (sob sob).
i am quasi-familiar with the concept of moment of inertia being the equivalent of mass in linear motion and angular velocity that of velocity (duh), but i have not found a set of formulae that would allow me to make a connection between the aforementioned...er... things...
i come with the rather unsound basis of a-level physics, which is why it will be an especially challenging task for you get me to understand it. good luck (and thanks).
cucumber.
2. Apr 12, 2004
$$\theta r = s$$
$$\omega r = v$$
$$\alpha r = a$$
$$\vec{L} = \vec{r} \times \vec{p}$$
$$\vec{\tau} = \vec{r} \times \vec{F}$$
3. Apr 13, 2004
### cucumber
i'm unsure about a couple of things, though...
what are the "s" and the theta in [theta]*r = s
what are the alpha and the "a" in [alpha]*r = a
what are the "r"'s in both the above equations (just to be sure...)
and finally, what are those two other equations all about???
i suppose that funny looking thing (like half a pi) is torque, but the rest i have absolutely no idea... sorry.
i'd be very grateful if you could clarify them a bit.
thanks again.
cucumber.
4. Apr 13, 2004
### Chen
In a circle of radius r the length of any arc is given by the angle it creates with the center of the circle times the radius: $$s = \theta r$$
Angular acceleration:
$$\alpha = \frac{a_t}{r}$$
http://hyperphysics.phy-astr.gsu.edu/hbase/rotq.html#rq
Angular momentum:
$$\vec{L} = \vec{r} \times \vec{p}$$
http://hyperphysics.phy-astr.gsu.edu/hbase/amom.html
Torque ('tau'):
$$\vec{\tau} = \vec{r} \times \vec{F}$$
http://hyperphysics.phy-astr.gsu.edu/hbase/torq2.html#tc
Precession of Gyroscope:
http://hyperphysics.phy-astr.gsu.edu/hbase/gyr.html#gyr
|
{"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": 1, "mathjax_asciimath": 0, "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": 0.929340660572052, "perplexity": 913.379468652189}, "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-2018-22/segments/1526794867085.95/warc/CC-MAIN-20180525102302-20180525122302-00562.warc.gz"}
|
https://www.physicsforums.com/threads/evolution-factor.64187/
|
# Evolution Factor
1. Feb 18, 2005
### scilover89
Beside mutation, molecular drive, and variation of genetic, what are the factors which triggled the evolution?
2. Feb 18, 2005
### Sariaht
The environment causes evolution as well,
but that wasn't the question, was it?
3. Feb 18, 2005
### iansmith
Staff Emeritus
Selection such as environmental condition and mating will have an effect on the genetic variation.
There is also other effect such as the founder effect and bottleneck effect. The founder effect is when a small group of individuals becomes isolated from the main population due to geographical reason. The bottleneck effect is cause by a sudden reduction in the number of individuals in a population. It is usually not related to genetic advantage. A flood or a mass killing could be examples.
4. Feb 24, 2005
### Phobos
Staff Emeritus
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8410152792930603, "perplexity": 4311.380977864193}, "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-2017-04/segments/1484560280899.42/warc/CC-MAIN-20170116095120-00090-ip-10-171-10-70.ec2.internal.warc.gz"}
|
https://fjp.at/posts/slam/fastslam/
|
The following sections summairze the Grid-based FastSLAM algorithm which is one instance of FastSLAM. This algorithm estimates the trajectory of a mobile robot while simultaneously creating a grid map of the environment. Grid-based FastSLAM is combination of a particle filter such as Adaptive Monte Carlo Localization (amcl) and a mapping algorithm such as occupancy grid mapping.
## SLAM Fundamentals
SLAM stands for Simultaneous Localization and Mapping sometimes refered to as Concurrent Localization and Mappping (CLAM). The SLAM algorithm combines localization and mapping, where a robot has access only to its own movement and sensory data. The robot must build a map while simultaneously localizing itself relative to the map.
The map and the robot pose will be uncertain, and the errors in the robot’s pose estimate and map will be correlated. The accuracy of the map depends on the accuracy of the localization and vice versa. Chicken and eggo problem: The map is needed for localization, and the robot’s pose is needed for mapping. This makes SLAM a real challenge but is essential for mobile robotics.
They must be able to move in environments they have never seen before. Examples are a vacuum cleaner where also the map can change due to moving furniture. Of course self driving vehicles require SLAM to update their maps while localizing themselfs in it.
There exist generally five categories of SLAM algorithms:
1. Extended Kalman Filter SLAM (EKF)
2. Sparse Extended Information Filter (SEIF)
3. Extended Information Form (EIF)
4. FastSLAM
5. GraphSLAM
This posts describes the FastSLAM approach which uses a particle filter and a low dimensional Extended Kalman filter. This algorithm will be adapted to grid maps which results in Grid-based FastSLAM. GraphSLAM on the other hand uses constraints to represent relationships between robot poses and the environment. With this, the algorithm tries to resolve all the constraints to create the most likely map given the data. An implementation of GraphSLAM is called Real Time Apperance Based Mapping (RTABMap).
### Localization
In Localization problems a map is known beforehand and the robot pose is estimated using its sensor mesaurements $z_{1:t}$, control inputs $u_{1:t}$ and its initial pose $x_{1:t-1}$. With this data, the new belief $p(x_{1:t}|x_{1:t-1}, z_{1:t}, u_{1:t})$ can be computed as a probability distribution.
The localization estimation can be done with an Extended Kalman filter or Monte Carlo localization. With the Monte Carlo particle filter approach (MCL) each particle consists of the robot pose $(x, y, \theta)$ and its importance weight $w$. With motion and sensor updates, followed by resampling it is possible to estimate the robots pose.
### Mapping
In mapping problems the robot pose $x_{1:t}$ is known and the map $m_{t}$ at time $t$, either static or dynamic is unknown. Therefore the mapping problem is to find the posterior belief of the map $p(m_t|x_{1:t}, z_{1:t})$ given the robot poses and its measurements $z_{1:t}$.
The challenges in mapping are the number of state variables. In localization, only the robots pose is estimated with its $x$ and $y$ position. A map on the other hand lies in a continuous space. This can lead to infinitely many variables used to describe the map. Additional uncertainty is present through sensor data perception. Other challenges are the space and its geometries that should be mapped. For example repetitive environments such as walkways with no doors or similar looking ones.
The mapping algorithm that is described in this post is occupancy grid mapping. The algorithm can map any arbitrary environment by dividing it into a finite number of grid cells.
### SLAM Characteristics
SLAM exists in two forms which are Online SLAM and Full SLAM. In both forms, the algorithm estimates a map of its environment. However, Online SLAM estimates only single poses of the robot at specific time instances. Given the measurements $z_{1:t}$ and the control inputs $u_{1:t}$ the problem is to find the posterior belief of the robot pose $x_{t}$ at time $t$ and the map $m_{t}$.
$p(x_t, m|z\_{1:t}, u\_{1:t})$
Full SLAM on the other hand, estimates a full trajectory $x_{1:t}$ of the robot instead of just a single pose $x_t$ at a particular time step.
$p(x\_{1:t}, m|z\_{1:t}, u\_{1:t})$
Both problems are related to each other. The Online SLAM problem is result of integrating over the individual robot poses of the Full SLAM problem once at a time.
$\underbrace{p(x_t, m|z\_{1:t}, u\_{1:t})}_{\text{Online SLAM}} = \int \int \dots \int \underbrace{p(x\_{1:t}, m|z\_{1:t}, u\_{1:t})}_{\text{Full SLAM}} dx_1 dx_2 \dots dx_{t-1}$
Another characteristic of SLAM is that it is a continouous and discrete problem. Robot poses and object or landmark locations are continouous aspects of the SLAM problem. While sensing the environment continously, a discrete relation between detected objects and newly detected ones needs to be made. This relation is known by correspondance and helps the robot to detect if it has been in the same location. With SLAM, a mobile robot is establishing a discrete relation between newly and previously detected objects.
Correspondences should be included in the estimation problem meaning that the posterior includes the correspondence in both, the online and full SLAM problem.
\begin{align} &\text{Online SLAM: } p(x_t, m|z_{1:t}, u_{1:t}) \Rightarrow p(x_t, m, c_t|z_{1:t}, u_{1:t}) \\ &\text{Full SLAM: } p(x_{1:t}, m|z_{1:t}, u_{1:t}) \Rightarrow p(x_{1:t}, m, c_{1:t}|z_{1:t}, u_{1:t}) \end{align}
The advantage to add the correspondances to both problems is to have the robot better understand where it is located by establishing a relation between objects. The relation between the online SLAM and full SLAM problem is defined as
$\underbrace{p(x_t, m, c_t|z_{1:t}, u_{1:t})}_{\text{Online SLAM}} = \int \int \dots \int \sum_{c_1} \sum_{c_2} \dots \sum_{c_{t-1}} \underbrace{p(x_{1:t}, m, c_{1:t}|z_{1:t}, u_{1:t})}_{\text{Full SLAM}} dx_1 dx_2 \dots dx_{t-1}$
where it is now required to sum over the correspondence values and integrate over the robot poses from the Full SLAM problem.
### Challenges
The continouous portion consists of the robot poses and object locations and is highly dimensional. Also the discrete correspondences between detected objects are highly dimensional. These aspects require an approximation even when known correspondences are assumed.
There exist two instances of FastSLAM that require known correspondences which are FastSLAM 1.0 and FastSLAM 2.0. With these approaches each particle holds a guess of the robot trajectory and by doing so the SLAM problem is reduced to mapping with known poses.
To do SLAM without known correspondences, meaning without known landmark positions the algorithm in the following section can be used.
## Grid-based FastSLAM Algorithm
FastSLAM solves the Full SLAM problem with known correspondences using a custom particle filter approach known by the Rao-Blackwellized particle filter approach. This approach estimates a posterior over the trajectory using a particle filter. With this trajectory the robot poses are now known and the mapping problem is then solved with a low dimensional Extended Kalman Filter. This filter models independent features of the map with local Gaussians.
Using a grid map the environment can be modeled and FastSLAM gets extended without predefining any landmark positions. This allows to solve the SLAM problem in an arbitrary environment.
With the Grid-based FastSLAM algorithm, each particle holds a guess of the robot trajectory using a MCL particle filter. Addionaly, each particle maintains its own map by utilizing the occupancy grid mapping algorithm.
The steps of the algorithm consist of sampling motion $p(x_t|x_{t-1}^{[k]}, u_t)$, map estimation $p(m_t|z_t, x_t^{[k]}, m_{t-1}^{[k]})$ and importance weight $p(z_t|x_t^{[k]}, m^{[k]})$.
The algorithm takes the previous belief $X_{t-1}$ or pose, the actuation commands $u_t$ and the sensor measurements $z_t$ as input. Initially $M \in \mathbb{R}$ particles are generated randomly which defines the initial belief $\bar{X}_t$. The first for loop represents the motion, sensor and map update steps. Here, the pose of each particle is estimated and the likelihoods of the measurements and the map are updated. To update the measurements model likelihood the importance weight technique is used in the measurement_model_map function. In the update_occupancy_grid function, each particle updates its map using the occupancy grid mapping algorithm. The newly estimated k-th particle pose, map and likelihood of the measurement are all added to the hypotetical belief $\bar{X}_t$.
In the second for loop the resampling process of the particles takes place. The resampling is implementd using a resampling wheel technique. Here, particle measurements that are close to the robots real world measurement values are redrawn more frequently in upcoming iterations. The drawn particle poses and maps are added to the system belief $X_t$ which is returnd from the algorithm to start a new iteration with the next motion and sensor updates.
## ROS gmapping
The gmapping ROS package uses the Grid-based FastSLAM algorithm. This package contains the single slam_gmapping node, which subscribes to the tf and scans topics. Using these inputs, it generates a 2D occupancy grid map and outputs robot poses on the map and entropy topics. Additional map data is provided through the map_metadata topic. Another way to access the map is to use the service provided by the node. To demonstrate gmapping, turtlebot will be deployed in the willow garage environment inside gazebo. Moving the turtlebout around using the teleop package and running the slam_gmapping node will generate a map.
Refere to Wikipedia for a list of SLAM methods. There you can also find resources for the FastSLAM instances:
Further details about MCL are found in the paper of Sebastian Thrun et al. The gmapping algorithm can be found here.
## Reference
This post is a summary of the lesson on FastSLAM from the Robotics Nanodegree of Udacity.
Tags:
Categories:
Updated:
|
{"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": 2, "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": 1, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8451486825942993, "perplexity": 1442.3427793953147}, "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-2020-50/segments/1606141715252.96/warc/CC-MAIN-20201202175113-20201202205113-00538.warc.gz"}
|
https://algo.franklinqin0.me/three_sum.html
|
# Three Sum
## # Solution
The brute force solution doesn't sort and takes 3 nested for loops for a runtime of .
Sorting() was not a good practice in two sum as the runtime could be but should be used here, as the runtime is no less than .
### # Vanilla Two Pointers
Sort and then use two pointers to search for satisfied result. Caveat is to look out for duplicates.
Complexity:
• Time:
• Space:
def threeSum(self, nums: List[int]) -> List[List[int]]:
res = []
nums.sort()
for i in range(len(nums)-2):
# no need to continue searching b/c nums is sorted
if nums[i]>0:
break
# i>0 s.t. i-1>=0
# continue if curr==prev to eliminate duplicates on smallest elt
if i>0 and nums[i]==nums[i-1]:
continue
target = -nums[i]
left = i+1
right = len(nums)-1
while left<right:
if nums[left]+nums[right]==target:
res.append([nums[left], nums[i], nums[right]])
# if the current left/right is the same w/ the next, a duplicate would be returned
while left<right and nums[left]==nums[left+1]:
left+=1
while left<right and nums[right]==nums[right-1]:
right-=1
# update left/right after eliminating duplicates
left+=1
right-=1
elif nums[left]+nums[right]<target:
left+=1
else:
right-=1
return res
### # Return a Set
Also sort and then use two pointers, but the difference is returning a set rather than list.
To eliminate duplicates, add tuple rather than list to res as a HashSet.
Complexity:
• Time:
• Space:
def threeSum(self, nums: List[int]) -> List[List[int]]:
res = set()
n = len(nums)
nums.sort()
for i in range(n-2):
target = -nums[i]
left = i+1
right = n-1
while left<right:
# speed up a bit
if nums[i]>0:
break
if nums[left]+nums[right]==target:
res.add((nums[i],nums[left],nums[right]))
left += 1
right -= 1
elif nums[left]+nums[right]<target:
left += 1
else:
right -= 1
return res
Last Updated: 5/13/2020, 7:39:18 AM
|
{"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": 0.20934076607227325, "perplexity": 21494.012325384265}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "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-2020-29/segments/1593657151761.87/warc/CC-MAIN-20200714212401-20200715002401-00364.warc.gz"}
|
https://biust.pure.elsevier.com/en/publications/empirical-statistical-modeling-of-march-may-rainfall-prediction-o
|
# Empirical statistical modeling of March-May rainfall prediction over southern nations, nationalities and people’s region of Ethiopia
Wondimu Tadiwos Hailesilassie, Gizaw Mengistu Tsidu
Research output: Contribution to journalArticlepeer-review
## Abstract
Statistical predictive models were developed to investigate how global rainfall predictors relate to the March-May (MAM) rainfall over Southern Nations, Nationalities and People's Region (SNNPR) of Ethiopia. Data utilized in this study include station rainfall data, oceanic and atmospheric indices. Because of the spatial variations in the interannual variability and the annual cycle of rainfall, an agglomerative hierarchical cluster analyses were used to delineate a network of 20 stations over study area into three homogeneous rainfall regions in order to derive rainfall indices. Time series generated from the delineated regions were later used in the rainfall/teleconnection indices analyses. The methods employed were correlation analysis and multiple linear regressions. The regression modes were based on the training period from 1987-2007 and the models were validated against observation for the independent verification period of 2008-2012. Results obtained from the analysis revealed that sea surface temperature (SST) variations were the main drivers of seasonal rainfall variability. Although SSTs account for the majority of variance in seasonal rainfall, a moderate improvement of rainfall prediction was achieved with the inclusion of atmospheric indices in prediction models. The techniques clearly indicate that the models were reproducing and describing the pattern of the rainfall for the sites of interest. For the forecast to become useful at an operational level, further development of the model will be necessary to improve skill and to determine the error bounds of the forecast.
Original language English 569-578 10 Mausam 66 3 Published - 2015
## All Science Journal Classification (ASJC) codes
• Atmospheric Science
• Geophysics
## Fingerprint
Dive into the research topics of 'Empirical statistical modeling of March-May rainfall prediction over southern nations, nationalities and people’s region of Ethiopia'. Together they form a unique fingerprint.
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8509758710861206, "perplexity": 4512.621945245193}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "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-2022-21/segments/1652663016949.77/warc/CC-MAIN-20220528154416-20220528184416-00148.warc.gz"}
|
https://cs.biu.ac.il/en/node/4011
|
# On Notions of Distortion and an Almost Minimum Spanning Tree with constant Average Distortion
30/11/2017 - 12:00
Speaker:
Seminar:
Where:
Abstract:
Minimum Spanning Trees of weighted graphs are fundamental objects in numerous applications. In particular in distributed networks, the minimum spanning tree of the network is often used to route messages between network nodes. Unfortunately, while being most efficient in the total cost of connecting all nodes, minimum spanning trees fail miserably in the desired property of approximately preserving distances between pairs. While known lower bounds exclude the possibility of the worst case distortion of a tree being small, Abraham et al showed that there exists a spanning tree with constant average distortion. Yet, the weight of such a tree may be significantly larger than that of the MST. In this paper, we show that any weighted undirected graph admits a spanning tree whose weight is at most (1+\rho) times that of the MST, providing constant averagedistortion O(1/\rho).
The constant average distortion bound is implied by a stronger property of scaling distortion, i.e., improved distortion for smaller fractions of the pairs. The result is achieved by first showing the existence of a low weight spanner with small prioritized distortion, a property allowing to prioritize the nodes whose associated distortions will be improved. We show that prioritized distortion is essentially equivalent to coarse scaling distortion via a general transformation, which has further implications and may be of independent interest. In particular, we obtain an embedding for arbitrary metrics into Euclidean space with optimal prioritized distortion.
Joint work with Yair Bartal and Ofer Neiman.
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9506856799125671, "perplexity": 409.9229691496021}, "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-2019-51/segments/1575540481076.11/warc/CC-MAIN-20191205141605-20191205165605-00081.warc.gz"}
|
https://www.zbmath.org/authors/?q=ai%3Azhang.wujun
|
×
zbMATH — the first resource for mathematics
Zhang, Wujun
Compute Distance To:
Author ID: zhang.wujun Published as: Zhang, W.; Zhang, W. J.; Zhang, Wujun
Documents Indexed: 78 Publications since 1986, including 1 Book
all top 5
Co-Authors
0 single-authored 7 Nochetto, Ricardo Horacio 4 Cockburn, Bernardo 3 Neilan, Michael 3 Salgado, Abner J. 2 Ntogkas, Dimitrios 2 Walker, Shawn W. 1 Contreras, Andres A. 1 Cui, Jintao 1 Fu, Guosheng 1 Li, Zhuo 1 Qiu, Weifeng 1 Shi, Jine 1 Wei, Baojun 1 Xing, Lijuan 1 Xu, Xiang
all top 5
Serials
3 Mathematics of Computation 3 SIAM Journal on Numerical Analysis 2 IMA Journal of Numerical Analysis 2 European Series in Applied and Industrial Mathematics (ESAIM): Mathematical Modelling and Numerical Analysis 1 Journal of Computational Physics 1 Numerische Mathematik 1 Acta Physica Sinica 1 Journal of Scientific Computing 1 Journal of Nonlinear Science 1 Foundations of Computational Mathematics 1 Acta Numerica 1 Journal of Guangxi Normal University. Natural Science Edition
all top 5
Fields
17 Numerical analysis (65-XX) 13 Partial differential equations (35-XX) 2 Fluid mechanics (76-XX) 2 Statistical mechanics, structure of matter (82-XX) 1 Ordinary differential equations (34-XX) 1 Calculus of variations and optimal control; optimization (49-XX) 1 Probability theory and stochastic processes (60-XX) 1 Quantum theory (81-XX) 1 Game theory, economics, finance, and other social and behavioral sciences (91-XX) 1 Information and communication theory, circuits (94-XX)
Citations contained in zbMATH Open
54 Publications have been cited 237 times in 185 Documents Cited by Year
A posteriori error estimates for HDG methods. Zbl 1260.65099
Cockburn, Bernardo; Zhang, Wujun
2012
An analysis of HDG methods for convection-dominated diffusion problems. Zbl 1314.65142
Fu, Guosheng; Qiu, Weifeng; Zhang, Wujun
2015
Numerical analysis of strongly nonlinear PDEs. Zbl 1381.65092
Neilan, Michael; Salgado, Abner J.; Zhang, Wujun
2017
A posteriori error analysis for hybridizable discontinuous Galerkin methods for second-order elliptic problems. Zbl 1277.65089
Cockburn, Bernardo; Zhang, Wujun
2013
Discrete ABP estimate and convergence rates for linear elliptic equations in non-divergence form. Zbl 1397.65286
Nochetto, Ricardo H.; Zhang, Wujun
2018
An analysis of HDG methods for the Helmholtz equation. Zbl 1282.65151
Cui, Jintao; Zhang, Wujun
2014
Assessment of data redundancy in fuzzy relational databases based on semantic inclusion degree. Zbl 1338.68060
Ma, Z. M.; Zhang, W. J.; Ma, W. Y.
1999
Two-scale method for the Monge-Ampère equation: convergence to the viscosity solution. Zbl 1405.65154
Nochetto, R. H.; Ntogkas, D.; Zhang, W.
2019
An explicit Chebyshev pseudospectral multigrid method for incompressible Navier-Stokes equations. Zbl 1242.76224
Zhang, W.; Zhang, C. H.; Xi, G.
2010
Social influencing and associated random walk models: asymptotic consensus times on the complete graph. Zbl 1317.91007
Zhang, W.; Lim, C.; Sreenivasan, S.; Xie, J.; Szymanski, B. K.; Korniss, G.
2011
Rate of convergence of multistep codes started by variation of order and stepsize. Zbl 0727.65067
Shampine, L. F.; Zhang, W.
1990
An a posteriori error estimate for the variable-degree Raviart-Thomas method. Zbl 1296.65142
Cockburn, Bernardo; Zhang, Wujun
2014
Strengthened quantum Hamming bound. Zbl 1240.81007
Xing, Lijuan; Li, Zhuo; Zhang, Wujun
2011
Conceptual design of fuzzy object-oriented databases using extended entity-relationship model. Zbl 0979.68040
Ma, Z. M.; Zhang, W. J.; Ma, W. Y.; Chen, G. Q.
2001
A finite element method for nematic liquid crystals with variable degree of orientation. Zbl 1453.82090
Nochetto, Ricardo H.; Walker, Shawn W.; Zhang, Wujun
2017
Concurrent optimal design of modular robotic configuration. Zbl 1006.70006
Bi, Z. M.; Zhang, W. J.
2001
Effects of axial compression ratio of central columns on seismic performance of a multi-story underground structure. Zbl 1359.74304
Chen, Zhi Yi; Chen, Wei; Zhang, W.; Lou, M. L.
2016
Contraction property of adaptive hybridizable discontinuous Galerkin methods. Zbl 1332.65164
Cockburn, Bernardo; Nochetto, Ricardo H.; Zhang, Wujun
2016
An artificial neural network approach to mechanism kinematic chain isomorphism identification. Zbl 1049.70545
Kong, F. G.; Li, Q.; Zhang, W. J.
1999
Stochastic vibration model of gear transmission systems considering speed-dependent random errors. Zbl 0946.70505
Wang, Y.; Zhang, W. J.
1998
Instabilities in a combustion model with two free interfaces. Zbl 1429.35212
Addona, D.; Brauner, C.-M.; Lorenzi, L.; Zhang, W.
2020
The Ericksen model of liquid crystals with colloidal and electric effects. Zbl 1375.82119
Nochetto, Ricardo H.; Walker, Shawn W.; Zhang, Wujun
2018
Some further development on the eigensystem approach for graph isomorphism detection. Zbl 1074.05059
He, P. R.; Zhang, W. J.; Li, Q.
2005
Dynamic stability of a flexible spinning cylinder partially filled with liquid. Zbl 1110.74702
Tao, M.; Zhang, W.
2002
An elastic-plastic-cracking model for finite element analysis of indentation cracking in brittle materials. Zbl 1001.74108
Zhang, W.; Subhash, G.
2001
Post-buckling analysis of shell and membrane structures by dynamic relaxation method. Zbl 0988.74071
Zhang, W.; Hisada, T.; Noguchi, H.
2000
Semantic measure of fuzzy data in extended possibility-based fuzzy relational databases. Zbl 0957.68038
Ma, Z. M.; Zhang, W. J.; Ma, W. Y.
2000
Research on fractional critical covered graphs. Zbl 1458.05221
Wang, S.; Zhang, W.
2020
Finite element approximation of the Isaacs equation. Zbl 1433.65311
2019
Pointwise rates of convergence for the Oliker-Prussner method for the Monge-Ampère equation. Zbl 1407.65263
Nochetto, Ricardo H.; Zhang, Wujun
2019
Rates of convergence in $$W^2_p$$-norm for the Monge-Ampère equation. Zbl 1403.65115
Neilan, Michael; Zhang, Wujun
2018
Patchy, not patchy, or how much patchy? Classification of spatial patterns appearing in a model of biological invasion. Zbl 1384.92052
Petrovskaya, N.; Zhang, W.
2017
Numerical study of liquid film cooling in a rocket combustion chamber. Zbl 1189.76072
Zhang, H. W.; Tao, W. Q.; He, Y. L.; Zhang, W.
2006
State-space model with time delays for gene regulatory networks. Zbl 1073.92005
Wu, Fang-Xiang; Zhang, W. J.; Kusalik, Anthony J.
2004
Data dependencies in extended possibility-based fuzzy relational databases. Zbl 1015.68060
Ma, Z. M.; Zhang, W. J.; Ma, W. Y.; Mili, F.
2002
A finite element approach to dynamic modeling of flexible spatial compound bar-gear systems. Zbl 1140.70447
Wang, Y.; Zhang, W. J.; Cheung, H. M. E.
2001
3D dynamic modelling of spatial geared systems. Zbl 1015.70004
Wang, Y.; Cheung, H. M. E.; Zhang, W. J.
2001
Two-scale method for the Monge-Ampère equation: pointwise error estimates. Zbl 07323642
Nochetto, R. H.; Ntogkas, D.; Zhang, W.
2019
An adaptive SVD-Krylov reduced order model for surrogate based structural shape optimization through isogeometric boundary element method. Zbl 1441.74187
Li, S.; Trevelyan, J.; Wu, Z.; Lian, H.; Wang, D.; Zhang, W.
2019
On the rank of weighted graphs. Zbl 1356.05067
Zhang, W. J.; Yu, A. M.
2017
An analytical consideration of steady-state forced convection within a nanofluid-saturated metal foam. Zbl 1337.76060
Zhang, W.; Li, W.; Nakayama, A.
2015
Computation of Lyapunov values for two planar polynomial differential systems. Zbl 1173.34024
Li, Jing; Chen, Y.; Zhang, W.; Tian, Y.
2008
PD-type on-line learning control for systems with state uncertainties and measurement disturbances. Zbl 1172.93425
Ouyang, P. R.; Zhang, W. J.; Gupta, M. M.
2007
The ant colony algorithm for feature selection in high-dimension gene expression data for disease classification. Zbl 1146.92318
Robbins, K. R.; Zhang, W.; Bertrand, J. K.; Rekaya, R.
2007
Dynamic stability of a rotor partially filled with a viscous liquid. Zbl 1110.74701
Tao, M.; Zhang, W.
2002
Finite element modelling of geared multi-body system. Zbl 1044.70003
Wang, Yong; Cheung, H. M. E.; Zhang, W. J.
2002
Fuzzy data compression based on data dependencies. Zbl 1015.68052
Ma, Z. M.; Zhang, W. J.; Mili, F.
2002
The constant-Jacobian method for kinematics of a three-DOF planar micro-motion stage. Zbl 1114.70304
Zhang, W. J.; Zou, J.; Watson, L. G.; Zhao, W.; Zong, G. H.; Bi, S. S.
2002
A generic Petri net model for flexible manufacturing systems and its use for FMS control software testing. Zbl 0945.90538
Zhang, W. J.; Li, Q.; Bi, Z. M.; Zha, X. F.
2000
An integrated intelligent approach to process diagnosis in process industries. Zbl 0949.90559
Jiao, J.; Zhang, W.; Zhao, Zhenyin; Cha, J.
1999
Automatic communication from a neutral object model of mechanism to mechanism analysis programs based on a finite element approach in a software environment for CADCAM of mechanisms. Zbl 0920.73352
Zhang, W. J.; van der Werff, K.
1998
Response of an sdof system to periodic external and parametric excitations with random phase modulations. Zbl 1232.70038
Dimentberg, M.; Hou, Z.; Noori, M.; Zhang, W.
1996
Efficient integration of ordinary differential equations by transformation. Zbl 0686.65035
Shampine, L. F.; Zhang, W.
1988
Dynamic stability of the rotating shaft made of Boltzmann viscoelastic solid. Zbl 0588.73090
Zhang, W.; Ling, F. H.
1986
Instabilities in a combustion model with two free interfaces. Zbl 1429.35212
Addona, D.; Brauner, C.-M.; Lorenzi, L.; Zhang, W.
2020
Research on fractional critical covered graphs. Zbl 1458.05221
Wang, S.; Zhang, W.
2020
Two-scale method for the Monge-Ampère equation: convergence to the viscosity solution. Zbl 1405.65154
Nochetto, R. H.; Ntogkas, D.; Zhang, W.
2019
Finite element approximation of the Isaacs equation. Zbl 1433.65311
2019
Pointwise rates of convergence for the Oliker-Prussner method for the Monge-Ampère equation. Zbl 1407.65263
Nochetto, Ricardo H.; Zhang, Wujun
2019
Two-scale method for the Monge-Ampère equation: pointwise error estimates. Zbl 07323642
Nochetto, R. H.; Ntogkas, D.; Zhang, W.
2019
An adaptive SVD-Krylov reduced order model for surrogate based structural shape optimization through isogeometric boundary element method. Zbl 1441.74187
Li, S.; Trevelyan, J.; Wu, Z.; Lian, H.; Wang, D.; Zhang, W.
2019
Discrete ABP estimate and convergence rates for linear elliptic equations in non-divergence form. Zbl 1397.65286
Nochetto, Ricardo H.; Zhang, Wujun
2018
The Ericksen model of liquid crystals with colloidal and electric effects. Zbl 1375.82119
Nochetto, Ricardo H.; Walker, Shawn W.; Zhang, Wujun
2018
Rates of convergence in $$W^2_p$$-norm for the Monge-Ampère equation. Zbl 1403.65115
Neilan, Michael; Zhang, Wujun
2018
Numerical analysis of strongly nonlinear PDEs. Zbl 1381.65092
Neilan, Michael; Salgado, Abner J.; Zhang, Wujun
2017
A finite element method for nematic liquid crystals with variable degree of orientation. Zbl 1453.82090
Nochetto, Ricardo H.; Walker, Shawn W.; Zhang, Wujun
2017
Patchy, not patchy, or how much patchy? Classification of spatial patterns appearing in a model of biological invasion. Zbl 1384.92052
Petrovskaya, N.; Zhang, W.
2017
On the rank of weighted graphs. Zbl 1356.05067
Zhang, W. J.; Yu, A. M.
2017
Effects of axial compression ratio of central columns on seismic performance of a multi-story underground structure. Zbl 1359.74304
Chen, Zhi Yi; Chen, Wei; Zhang, W.; Lou, M. L.
2016
Contraction property of adaptive hybridizable discontinuous Galerkin methods. Zbl 1332.65164
Cockburn, Bernardo; Nochetto, Ricardo H.; Zhang, Wujun
2016
An analysis of HDG methods for convection-dominated diffusion problems. Zbl 1314.65142
Fu, Guosheng; Qiu, Weifeng; Zhang, Wujun
2015
An analytical consideration of steady-state forced convection within a nanofluid-saturated metal foam. Zbl 1337.76060
Zhang, W.; Li, W.; Nakayama, A.
2015
An analysis of HDG methods for the Helmholtz equation. Zbl 1282.65151
Cui, Jintao; Zhang, Wujun
2014
An a posteriori error estimate for the variable-degree Raviart-Thomas method. Zbl 1296.65142
Cockburn, Bernardo; Zhang, Wujun
2014
A posteriori error analysis for hybridizable discontinuous Galerkin methods for second-order elliptic problems. Zbl 1277.65089
Cockburn, Bernardo; Zhang, Wujun
2013
A posteriori error estimates for HDG methods. Zbl 1260.65099
Cockburn, Bernardo; Zhang, Wujun
2012
Social influencing and associated random walk models: asymptotic consensus times on the complete graph. Zbl 1317.91007
Zhang, W.; Lim, C.; Sreenivasan, S.; Xie, J.; Szymanski, B. K.; Korniss, G.
2011
Strengthened quantum Hamming bound. Zbl 1240.81007
Xing, Lijuan; Li, Zhuo; Zhang, Wujun
2011
An explicit Chebyshev pseudospectral multigrid method for incompressible Navier-Stokes equations. Zbl 1242.76224
Zhang, W.; Zhang, C. H.; Xi, G.
2010
Computation of Lyapunov values for two planar polynomial differential systems. Zbl 1173.34024
Li, Jing; Chen, Y.; Zhang, W.; Tian, Y.
2008
PD-type on-line learning control for systems with state uncertainties and measurement disturbances. Zbl 1172.93425
Ouyang, P. R.; Zhang, W. J.; Gupta, M. M.
2007
The ant colony algorithm for feature selection in high-dimension gene expression data for disease classification. Zbl 1146.92318
Robbins, K. R.; Zhang, W.; Bertrand, J. K.; Rekaya, R.
2007
Numerical study of liquid film cooling in a rocket combustion chamber. Zbl 1189.76072
Zhang, H. W.; Tao, W. Q.; He, Y. L.; Zhang, W.
2006
Some further development on the eigensystem approach for graph isomorphism detection. Zbl 1074.05059
He, P. R.; Zhang, W. J.; Li, Q.
2005
State-space model with time delays for gene regulatory networks. Zbl 1073.92005
Wu, Fang-Xiang; Zhang, W. J.; Kusalik, Anthony J.
2004
Dynamic stability of a flexible spinning cylinder partially filled with liquid. Zbl 1110.74702
Tao, M.; Zhang, W.
2002
Data dependencies in extended possibility-based fuzzy relational databases. Zbl 1015.68060
Ma, Z. M.; Zhang, W. J.; Ma, W. Y.; Mili, F.
2002
Dynamic stability of a rotor partially filled with a viscous liquid. Zbl 1110.74701
Tao, M.; Zhang, W.
2002
Finite element modelling of geared multi-body system. Zbl 1044.70003
Wang, Yong; Cheung, H. M. E.; Zhang, W. J.
2002
Fuzzy data compression based on data dependencies. Zbl 1015.68052
Ma, Z. M.; Zhang, W. J.; Mili, F.
2002
The constant-Jacobian method for kinematics of a three-DOF planar micro-motion stage. Zbl 1114.70304
Zhang, W. J.; Zou, J.; Watson, L. G.; Zhao, W.; Zong, G. H.; Bi, S. S.
2002
Conceptual design of fuzzy object-oriented databases using extended entity-relationship model. Zbl 0979.68040
Ma, Z. M.; Zhang, W. J.; Ma, W. Y.; Chen, G. Q.
2001
Concurrent optimal design of modular robotic configuration. Zbl 1006.70006
Bi, Z. M.; Zhang, W. J.
2001
An elastic-plastic-cracking model for finite element analysis of indentation cracking in brittle materials. Zbl 1001.74108
Zhang, W.; Subhash, G.
2001
A finite element approach to dynamic modeling of flexible spatial compound bar-gear systems. Zbl 1140.70447
Wang, Y.; Zhang, W. J.; Cheung, H. M. E.
2001
3D dynamic modelling of spatial geared systems. Zbl 1015.70004
Wang, Y.; Cheung, H. M. E.; Zhang, W. J.
2001
Post-buckling analysis of shell and membrane structures by dynamic relaxation method. Zbl 0988.74071
Zhang, W.; Hisada, T.; Noguchi, H.
2000
Semantic measure of fuzzy data in extended possibility-based fuzzy relational databases. Zbl 0957.68038
Ma, Z. M.; Zhang, W. J.; Ma, W. Y.
2000
A generic Petri net model for flexible manufacturing systems and its use for FMS control software testing. Zbl 0945.90538
Zhang, W. J.; Li, Q.; Bi, Z. M.; Zha, X. F.
2000
Assessment of data redundancy in fuzzy relational databases based on semantic inclusion degree. Zbl 1338.68060
Ma, Z. M.; Zhang, W. J.; Ma, W. Y.
1999
An artificial neural network approach to mechanism kinematic chain isomorphism identification. Zbl 1049.70545
Kong, F. G.; Li, Q.; Zhang, W. J.
1999
An integrated intelligent approach to process diagnosis in process industries. Zbl 0949.90559
Jiao, J.; Zhang, W.; Zhao, Zhenyin; Cha, J.
1999
Stochastic vibration model of gear transmission systems considering speed-dependent random errors. Zbl 0946.70505
Wang, Y.; Zhang, W. J.
1998
Automatic communication from a neutral object model of mechanism to mechanism analysis programs based on a finite element approach in a software environment for CADCAM of mechanisms. Zbl 0920.73352
Zhang, W. J.; van der Werff, K.
1998
Response of an sdof system to periodic external and parametric excitations with random phase modulations. Zbl 1232.70038
Dimentberg, M.; Hou, Z.; Noori, M.; Zhang, W.
1996
Rate of convergence of multistep codes started by variation of order and stepsize. Zbl 0727.65067
Shampine, L. F.; Zhang, W.
1990
Efficient integration of ordinary differential equations by transformation. Zbl 0686.65035
Shampine, L. F.; Zhang, W.
1988
Dynamic stability of the rotating shaft made of Boltzmann viscoelastic solid. Zbl 0588.73090
Zhang, W.; Ling, F. H.
1986
all top 5
Cited by 382 Authors
6 Nochetto, Ricardo Horacio 6 Yoshioka, Hidekazu 5 Bui-Thanh, Tan 5 Cockburn, Bernardo 5 Solano, Manuel E. 5 Zhang, Wujun 4 Chen, Gang 4 Feng, Xiaobing 4 Leng, Haitao 4 Neilan, Michael 4 Qiu, Weifeng 4 Walker, Shawn W. 4 Zhang, Yangwen 3 Brauner, Claude-Michel 3 Chen, Yanping 3 Gallistl, Dietmar 3 Guo, Lixin 3 Ikhile, Monday Ndidi Oziegbe 3 Mackerle, Jaroslav 3 Wang, Haotian 3 Wang, Jingyue 3 Yaegashi, Yuta 3 Yoshioka, Yumi 3 Zhang, Hongying 3 Zhang, Shun 2 Chen, Huangxin 2 Firouz-Abadi, R. D. 2 Glowinski, Roland 2 Ikhile, M. N. O. 2 Kröner, Dietmar 2 Lewis, Thomas Lee 2 Li, Bin 2 Li, Huifang 2 Liu, Jingbo 2 Lorenzi, Luca 2 Ma, Shugen 2 Ma, Wenyu 2 Ma, Zhenming 2 Mili, Fatma 2 Muralikrishnan, Sriramkrishnan 2 Otunta, F. O. 2 Oyarzúa, Ricardo 2 Peraire, Jaume 2 Petrovskaya, Natalia B. 2 Rokyta, Mirko 2 Sequeira, Filánder A. 2 Shen, Jiguang 2 Shi, Ke 2 Singler, John R. 2 Siraj-ul-Islam 2 Tran, Minh-Binh 2 Wang, Yuechao 2 Wu, Shuonan 2 Zhang, Minghui 2 Zhang, Wenxin 2 Zhou, Sizhong 2 Zúñiga, Paulo 1 Abbasbandy, Saeid 1 Abedin, Farhan 1 Agbanusi, Ikemefuna Chukwuemeka 1 Aïd, René 1 Ainsworth, Mark 1 Akbari, Saieed 1 Allahviranloo, Tofigh 1 Allery, Cyrille 1 Alsubaie, Muhammad Ali 1 Ammar, Amine 1 Araki, Luciano Kiyoshi 1 Aranishi, Futoshi 1 Araya, Rodolfo A. 1 Arbogast, Todd 1 Awais, Mian Muhammad 1 Aziz, Imran 1 Baczynski, Michal 1 Baghani, Mostafa 1 Bang, Jeongho 1 Bauch, Chris T. 1 Bedregal, Benjamín Callejas 1 Bedregal, Benjamín R. Callejas 1 Bera, P. K. 1 Bhattacharyya, Samit 1 Bi, Zhenming 1 Bjørke, Jan T. 1 Bobryk, Roman V. 1 Borthagaray, Juan Pablo 1 Bouaziz, Rafik 1 Brenner, Susanne Cecelia 1 Bronski, Jared C. 1 Bujalski, Julia 1 Bustince, Humberto 1 Bustinza, Rommel A. 1 Caboussat, Alexandre 1 Cai, Zhiqiang 1 Cai, Zhonglun 1 Carpinteri, Alberto 1 Chakhar, Salem 1 Chao, Daniel Yuh 1 Chaui-Berlinck, J. G. 1 Chen, Haodi 1 Chen, Hongtao ...and 282 more Authors
all top 5
Cited in 71 Serials
17 Journal of Scientific Computing 10 SIAM Journal on Numerical Analysis 9 Journal of Computational and Applied Mathematics 8 Computers & Mathematics with Applications 7 Computer Methods in Applied Mechanics and Engineering 6 Fuzzy Sets and Systems 6 Applied Mathematical Modelling 5 Journal of Computational Physics 5 Mathematics of Computation 5 Applied Mathematics and Computation 5 SIAM Journal on Scientific Computing 5 International Journal of Computational Methods 4 Engineering Computations 4 Quantum Information Processing 3 Information Sciences 3 Numerische Mathematik 3 International Journal of Production Research 3 International Journal of Intelligent Systems 3 Advances in Computational Mathematics 3 Engineering Analysis with Boundary Elements 3 Mechanism and Machine Theory 3 European Series in Applied and Industrial Mathematics (ESAIM): Mathematical Modelling and Numerical Analysis 2 International Journal of Theoretical Physics 2 Physics Reports 2 Chaos, Solitons and Fractals 2 Applied Numerical Mathematics 2 International Journal of Approximate Reasoning 2 International Journal of Computer Mathematics 2 International Journal of Nonlinear Sciences and Numerical Simulation 2 Journal of Numerical Mathematics 2 Science in China. Series F 2 Discrete and Continuous Dynamical Systems. Series S 2 International Journal of Structural Stability and Dynamics 2 Journal of Theoretical Biology 1 Computers and Fluids 1 Discrete Mathematics 1 International Journal of General Systems 1 International Journal of Systems Science 1 Journal of Fluid Mechanics 1 Journal of the Franklin Institute 1 Physica A 1 Calcolo 1 Journal of Differential Equations 1 Mathematics and Computers in Simulation 1 Meccanica 1 Proceedings of the American Mathematical Society 1 Applied Mathematics and Mechanics. (English Edition) 1 Annales de l’Institut Henri Poincaré. Analyse Non Linéaire 1 Acta Mathematicae Applicatae Sinica. English Series 1 Computers & Operations Research 1 Applied Mathematics Letters 1 International Journal of Adaptive Control and Signal Processing 1 Pattern Recognition 1 SIAM Journal on Applied Mathematics 1 SIAM Review 1 International Journal of Robust and Nonlinear Control 1 Communications in Numerical Methods in Engineering 1 Mathematical Problems in Engineering 1 Soft Computing 1 Journal of Biological Systems 1 Journal of Applied Mathematics 1 Bulletin of the Brazilian Mathematical Society. New Series 1 Journal of Intelligent and Fuzzy Systems 1 International Journal of Fracture 1 Contributions to Discrete Mathematics 1 Journal of Biological Dynamics 1 International Journal for Computational Methods in Engineering Science and Mechanics 1 Science China. Mathematics 1 Mathematics 1 Philosophical Transactions of the Royal Society of London. A. Mathematical, Physical and Engineering Sciences 1 Results in Applied Mathematics
all top 5
Cited in 25 Fields
94 Numerical analysis (65-XX) 55 Partial differential equations (35-XX) 29 Fluid mechanics (76-XX) 21 Mechanics of deformable solids (74-XX) 20 Computer science (68-XX) 15 Ordinary differential equations (34-XX) 12 Mechanics of particles and systems (70-XX) 10 Systems theory; control (93-XX) 9 Biology and other natural sciences (92-XX) 8 Mathematical logic and foundations (03-XX) 8 Game theory, economics, finance, and other social and behavioral sciences (91-XX) 7 Classical thermodynamics, heat transfer (80-XX) 7 Quantum theory (81-XX) 6 Combinatorics (05-XX) 6 Dynamical systems and ergodic theory (37-XX) 6 Calculus of variations and optimal control; optimization (49-XX) 5 Optics, electromagnetic theory (78-XX) 5 Geophysics (86-XX) 5 Operations research, mathematical programming (90-XX) 5 Information and communication theory, circuits (94-XX) 3 Probability theory and stochastic processes (60-XX) 2 Statistics (62-XX) 2 Statistical mechanics, structure of matter (82-XX) 1 Operator theory (47-XX) 1 Global analysis, analysis on manifolds (58-XX)
|
{"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": 1, "mathjax_asciimath": 0, "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": 0.7095411419868469, "perplexity": 12748.004088161482}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "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-2021-25/segments/1623487633444.37/warc/CC-MAIN-20210617192319-20210617222319-00154.warc.gz"}
|
https://ask.sagemath.org/answers/45678/revisions/
|
# Revision history [back]
a=QQ(-1)
matrix(QQ,1000,1000,lambda i,j:a)
oddly enough the following is faster:
from itertools import repeat
matrix(QQ,1000,1000,repeat(a,1000000))
Of course, select the appropriate ring in your own applications.
|
{"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": 0.2293667048215866, "perplexity": 11490.524179753953}, "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-2022-49/segments/1669446710808.72/warc/CC-MAIN-20221201085558-20221201115558-00234.warc.gz"}
|
https://math.cornell.edu/lower-level-courses
|
# Entry-Level Courses for Freshmen and Sophomores
## You are here
Please consult First Steps in Math for assistance in selecting an appropriate course.
### MATH 1006 - Academic Support for MATH 1106
Spring 2020. 1 credit. S/U grades only.
Students should contact their college for the most up-to-date information regarding if and how credits for this course will count toward graduation, and/or be considered regarding academic standing.
Reviews material presented in MATH 1106 lectures, provides problem-solving techniques and tips as well as prelim review. Provides further instruction for students who need reinforcement. Not a substitute for attending MATH 1106 lectures or discussions.
### MATH 1011 - Academic Support for MATH 1110
Fall 2019, Spring 2020. 1 credit. S/U grades only.
Students should contact their college for the most up-to-date information regarding if and how credits for this course will count toward graduation, and/or be considered regarding academic standing.
Reviews material presented in MATH 1110 lectures, provides problem-solving techniques and tips as well as prelim review. Provides further instruction for students who need reinforcement. Not a substitute for attending MATH 1110 lectures.
### MATH 1012 - Academic Support for MATH 1120
Fall 2019, Spring 2020. 1 credit. S/U grades only.
Students should contact their college for the most up-to-date information regarding if and how credits for this course will count toward graduation, and/or be considered regarding academic standing.
Reviews material presented in MATH 1120 lectures, provides problem-solving techniques and tips as well as prelim review. Provides further instruction for students who need reinforcement. Not a substitute for attending MATH 1120 lectures or discussions.
### MATH 1021 - Academic Support for MATH 2210
Fall 2019, Spring 2020. 1 credit. S/U grades only.
Reviews material presented in MATH 2210 lectures, provides problem-solving techniques and tips as well as prelim review. Provides further instruction for students who need reinforcement. Not a substitute for attending MATH 2210 lectures or discussions.
### MATH 1101 - Calculus Preparation
Fall 2019. 1 credit. Letter grades only.
Introduces topics in calculus: limits, rates of change, definition of and techniques for finding derivatives, relative and absolute extrema, and applications. The calculus content of the course is similar to 1/3 of the content covered in MATH 1106 and MATH 1110. In addition, the course includes a variety of topics of algebra, with emphasis on the development of linear, power, exponential, logarithmic, and trigonometric functions. Because of the strong emphasis on graphing, students will have a better understanding of asymptotic behavior of these functions.
### MATH 1105 - Finite Mathematics for the Life and Social Sciences
Fall 2019. 3 credits. Student option grading.
Prerequisite: three years of high school mathematics, including trigonometry and logarithms.
Introduction to linear algebra, probability, and Markov chains that develops the parts of the theory most relevant for applications. Specific topics include: equations of lines, the method of least squares, solutions of linear systems, matrices; basic concepts of probability, permutations, combinations, binomial distribution, mean and variance, and the normal approximation to the binomial distribution. Examples from biology and the social sciences are used.
### MATH 1106 - Modeling with Calculus for the Life Sciences
Spring 2020. 3 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will not receive credit for both MATH 1106 and MATH 1110. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: three years of high school mathematics (including trigonometry and logarithms) or a precalculus course (e.g., MATH 1101). No prior knowledge of calculus is required. Students who plan to take more than one semester of calculus should take MATH 1110 rather than MATH 1106.
The goal of this course is to give students a strong basis in some quantitative skills needed in the life and social sciences. There will be an emphasis on modeling, using fundamental concepts from calculus developed in the course, including: derivatives, integrals, and introductory differential equations. Examples from the life sciences are used throughout the course. To give a concrete example, we will study predator-prey populations. We will write down mathematical models that describe the evolution of these populations, analyze both quantitative and qualitative properties to make predictions about the future of these populations, and discuss the assumptions and limitations of the models.
Note that while we will cover the topics of derivatives and integrals, this course has a different, much more applied, focus from courses such as MATH 1110 Calculus I or a typical high school calculus course.
### MATH 1110 - Calculus I
Summer 2019 (6-week), Fall 2019, Spring 2020. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will not receive credit for both MATH 1110 and MATH 1106. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: three years of high school mathematics (including trigonometry and logarithms) or a precalculus course (e.g., MATH 1101). MATH 1110 can serve as a one-semester introduction to calculus or as part of a two-semester sequence in which it is followed by MATH 1120 or MATH 1220.
Topics include functions and graphs, limits and continuity, differentiation and integration of algebraic, trigonometric, inverse trig, logarithmic, and exponential functions; applications of differentiation, including graphing, max-min problems, tangent line approximation, implicit differentiation, and applications to the sciences; the mean value theorem; and antiderivatives, definite and indefinite integrals, the fundamental theorem of calculus, substitution in integration, the area under a curve.
### MATH 1120 - Calculus II
Fall 2019, Spring 2020. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 1120, 1220, 1910. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: MATH 1110 with a grade of C or better, excellent performance in MATH 1106, or equivalent AP credit. Those who do well in MATH 1110 and expect to major in mathematics or a strongly mathematics-related field should take MATH 1220 instead of 1120.
Focuses on integration: applications, including volumes and arc length; techniques of integration, approximate integration with error estimates, improper integrals, differential equations (separation of variables, initial conditions, systems, some applications). Also covers infinite sequences and series: definition and tests for convergence, power series, Taylor series with remainder, and parametric equations.
### MATH 1220 - [Theoretical Calculus II]
Fall. Next offered 2020-2021. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 1120, 1220, 1910. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: one semester of calculus with high performance or equivalent AP credit. Takes a more theoretical approach to calculus than MATH 1120. Students planning to continue with MATH 2130 are advised to take 1120 instead of this course.
Topics include differentiation and integration of elementary transcendental functions, techniques of integration, applications, polar coordinates, infinite series, and complex numbers, as well as an introduction to proving theorems.
### MATH 1300 - Mathematical Explorations
Fall 2019. 3 credits. Student option grading.
Pre-enrollment limited to Arts and Sciences students. Out-of-college students may be able to enroll during the add/drop period.
For students who wish to experience how mathematical ideas naturally evolve. The course emphasizes ideas and imagination rather than techniques and calculations. Homework involves students in actively investigating mathematical ideas. Topics vary depending on the instructor. Some assessment through writing assignments.
### MATH 1340 - Strategy, Cooperation, and Conflict
Spring 2020. 3 credits. Student option grading.
We apply mathematical reasoning to problems arising in the social sciences. We discuss game theory and its applications to questions of governing and the analysis of political conflicts. The problem of finding fair election procedures to choose among three or more alternatives is analyzed.
### MATH 1710 - Statistical Theory and Application in the Real World
Fall 2019, Spring 2020. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: AEM 2100, BTRY 3010, BTRY 6010, ENGRD 2700, HADM 2010, ILRST 2100, ILRST 6100, MATH 1710, PAM 2100, PAM 2101, PSYCH 2500, SOC 3010, STSCI 2100, STSCI 2150, STSCI 2200. In addition, no credit for MATH 1710 if taken after ECON 3130, ECON 3140, ECON 3125, MATH 4720, or any other upper-level course focusing on the statistical sciences (e.g., those counting toward the statistics concentration for the math major).
Prerequisite: high school mathematics. No previous familiarity with computers presumed.
Introductory statistics course discussing techniques for analyzing data occurring in the real world and the mathematical and philosophical justification for these techniques. Topics include population and sample distributions, central limit theorem, statistical theories of point estimation, confidence intervals, testing hypotheses, the linear model, and the least squares estimator. The course concludes with a discussion of tests and estimates for regression and analysis of variance (if time permits). The computer is used to demonstrate some aspects of the theory, such as sampling distributions and the Central Limit Theorem. In the lab portion of the course, students learn and use computer-based methods for implementing the statistical methodology presented in the lectures.
### MATH 1910 - Calculus For Engineers
Summer 2019 (6-week), Fall 2019, Spring 2020. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 1120, 1220, 1910. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: three years high school mathematics, including trigonometry and logarithms, and at least one course in differential and integral calculus or equivalent AP credit.
Essentially a second course in calculus. Topics include techniques of integration, finding areas and volumes by integration, exponential growth, partial fractions, infinite sequences and series, tests of convergence, and power series.
### MATH 1920 - Multivariable Calculus for Engineers
Summer 2019 (6-week), Fall 2019, Spring 2020. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 1920, 2130, 2220, 2240. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: MATH 1910 or equivalent AP credit.
Introduction to multivariable calculus. Topics include partial derivatives, double and triple integrals, line and surface integrals, vector fields, Green’s theorem, Stokes’ theorem, and the divergence theorem.
### MATH 2130 - Calculus III
Spring 2020. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 1920, 2130, 2220, 2240. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: MATH 1120, 1220, or 1910, or equivalent AP credit. Designed for students who wish to master the basic techniques of multivariable calculus, but whose major will not require a substantial amount of mathematics. Students who plan to major or minor in mathematics or take upper-level math courses should take MATH 1920, 2220, or 2240 rather than MATH 2130.
Topics include vectors and vector-valued functions; multivariable and vector calculus including multiple and line integrals; first- and second-order differential equations with applications; systems of differential equations; and elementary partial differential equations. Optional topics may include Green's theorem, Stokes' theorem, and the divergence theorem.
### MATH 2210 - Linear Algebra
Fall 2019, Spring 2020. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 2210, 2230, 2310, 2940. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: two semesters of calculus with high performance, equivalent AP credit, or permission of department. Recommended for students who plan to major or minor in mathematics or a related field. For a more applied version of this course, see MATH 2310.
Topics include vector algebra, linear transformations, matrices, determinants, orthogonality, eigenvalues, and eigenvectors. Applications are made to linear differential or difference equations. The lectures introduce students to formal proofs. Students are required to produce some proofs in their homework and on exams.
### MATH 2220 - Multivariable Calculus
Fall 2019, Spring 2020. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 1920, 2130, 2220, 2240. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: MATH 2210. Recommended for students who plan to major or minor in mathematics or a related field.
Differential and integral calculus of functions in several variables, line and surface integrals as well as the theorems of Green, Stokes and Gauss.
### MATH 2230 - Theoretical Linear Algebra and Calculus
Fall 2019. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 2210, 2230, 2310, 2940. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: two semesters of calculus with grade of A– or better, equivalent AP credit, or permission of instructor. Designed for students who have been extremely successful in their previous calculus courses and for whom the notion of solving very hard problems and writing careful proofs is highly appealing. MATH 2230-2240 provides an integrated treatment of linear algebra and multivariable calculus at a higher theoretical level than in MATH 2210-2220.
Topics include vectors, matrices, and linear transformations; differential calculus of functions of several variables; inverse and implicit function theorems; quadratic forms, extrema, and manifolds; multiple and iterated integrals.
### MATH 2240 - Theoretical Linear Algebra and Calculus
Spring 2020. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 1920, 2130, 2220, 2240. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: MATH 2230. Designed for students who have been extremely successful in their previous calculus courses and for whom the notion of solving very hard problems and writing careful proofs is highly appealing. MATH 2230-2240 provides an integrated treatment of linear algebra and multivariable calculus at a higher theoretical level than in MATH 2210-2220.
Topics include vector fields; line integrals; differential forms and exterior derivative; work, flux, and density forms; integration of forms over parametrized domains; and Green's, Stokes', and divergence theorems.
### MATH 2310 - Linear Algebra with Applications
Fall 2019. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 2210, 2230, 2310, 2940. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: one semester of college-level calculus, such as MATH 1106 or MATH 1110, or equivalent AP credit. Students who plan to major or minor in mathematics or take upper-level math courses should take MATH 2210, 2230, or 2940 rather than MATH 2310.
Introduction to linear algebra for students who wish to focus on the practical applications of the subject. A wide range of applications are discussed and computer software may be used. The main topics are systems of linear equations, matrices, determinants, vector spaces, orthogonality, and eigenvalues. Typical applications are population models, input/output models, least squares, and difference equations.
### MATH 2810 - Deductive Logic
(also PHIL 3310)
Spring 2020. 4 credits. Student option grading.
Prerequisite: PHIL 2310 or MATH 2210 or MATH 2230 or explicit permission of instructor.
A mathematical study of the formal languages of propositional and predicate logic, including their syntax, semantics, and deductive systems. Various formal results will be established, most importantly soundness and completeness.
### MATH 2930 - Differential Equations for Engineers
Summer 2019 (6-week), Fall 2019, Spring 2020. 4 credits. Student option grading.
Prerequisite: MATH 1920. Taking MATH 2930 and 2940 simultaneously is not recommended.
Introduction to ordinary and partial differential equations. Topics include first order equations (separable, linear, homogeneous, exact); mathematical modeling (e.g., population growth, terminal velocity); qualitative methods (slope fields, phase plots, equilibria and stability); numerical methods; second order equations (method of undetermined coefficients, application to oscillations and resonance, boundary value problems and eigenvalues); and Fourier series. A substantial part of this course involves partial differential equations, such as the heat equation, the wave equation, and Laplace's equation. (This part must be present in any outside course being considered for transfer credit to Cornell as a substitute for MATH 2930.)
### MATH 2940 - Linear Algebra for Engineers
Summer 2019 (6-week), Fall 2019, Spring 2020. 4 credits. Student option grading.
Forbidden Overlap: Due to an overlap in content, students will receive credit for only one course in the following group: MATH 2210, 2230, 2310, 2940. For guidance in selecting an appropriate course, please consult First Steps in Math.
Prerequisite: MATH 1920. Taking MATH 2930 and 2940 simultaneously is not recommended.
Linear algebra and its applications. Topics include matrices, determinants, vector spaces, eigenvalues and eigenvectors, orthogonality and inner product spaces; applications include brief introductions to difference equations, Markov chains, and systems of linear ordinary differential equations. May include computer use in solving problems.
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8202680349349976, "perplexity": 1896.5121075263223}, "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-2019-47/segments/1573496668782.15/warc/CC-MAIN-20191117014405-20191117042405-00179.warc.gz"}
|
https://infoscience.epfl.ch/record/202320
|
## Vortex lattice structure in BaFe2(As0.67P0.33)(2) via small-angle neutron scattering
We have observed a magnetic vortex lattice (VL) in BaFe2(As0.67P0.33)(2) (BFAP) single crystals by small-angle neutron scattering. With the field along the c axis, a nearly isotropic hexagonal VL was formed in the field range from 1 to 16 T, and no symmetry changes in the VL were observed. The temperature dependence of the VL signal was measured and confirms the presence of (non-d-wave) nodes in the superconducting gap structure for measurements at 5 T and below. The nodal effects were suppressed at high fields. At low fields, a VL reorientation transition was observed between 1 and 3 T, with the VL orientation changing by 45 degrees. Below 1 T, the VL structure was strongly affected by pinning and the diffraction pattern had a fourfold symmetry. We suggest that this (and possibly also the VL reorientation) is due to pinning to defects aligned with the crystal structure, rather than being intrinsic. The temperature dependence of the scaled intensity suggests that BFAP possesses at least one full gap and one nodal gap with circular symmetry. Judging from the symmetry, the node structure should take the form of an "accidental" circular line node, which is consistent with recent angle-resolved photoemission spectroscopy results.
Published in:
Physical Review B, 90, 12
Year:
2014
Publisher:
College Pk, Amer Physical Soc
ISSN:
1098-0121
Laboratories:
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9502876400947571, "perplexity": 2197.339217979824}, "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-2018-43/segments/1539583512014.61/warc/CC-MAIN-20181018194005-20181018215505-00294.warc.gz"}
|
http://mathhelpforum.com/algebra/149675-unique-solution.html
|
1. ## unique solution
For what values of k equation |x+1|-|x-1|=kx+1 have unique solution?
2. Originally Posted by Garas
For what values of k equation |x+1|-|x-1|=kx+1 have unique solution?
Since absolute value has two separate formulas depending on whether the number inside the absolute value is positive or negative. That means you need to look at x+1< 0 (x< -1), x+1> 0 (x> -1), x-1< 0 (x< 1), and x-1> 0 (x> 1).
That means we need to look at three intervals: x< -1, -1< x< 1, and x> 1.
If x< -1, both x+1< 0 and x-1< 0 so the equation becomes -(x+1)-(-(x-1))= -2= 2k+1 which has no solution for x if x is not -3/2 but an infinite number of solutions if k= 3/2 (since then the equation reduces to -2= -2 which is true for all x).
If -1< x< 1, x+1> 0 but x-1< 0 so the equation becomes (x+1)-(-(x-1))= 2x= 2k+1 which has a single solution for x no matter what k is.
If x> 1, both x+1>0 and x-1> 0 so the equation becomes (x+1)- (x-1)= 2= 2k+1 which has no solution for x is k is not 1/2 but has an infinite number of solutions if k= 1/2 (because then the equation reduces to 2= 2 which is true for all x).
3. What happened with x in -(x+1)-(-(x-1))= -2= 2k+1. Equation is |x+1|-|x-1|=kx+1. I don't understand that part.
4. You said that there is infinite number of solutions if k=3/2 but i find only one solution and that is -2. abs(x+1)-abs(x-1)=(3/2)x+1 - Wolfram|Alpha
5. Originally Posted by Garas
What happened with x in -(x+1)-(-(x-1))= -2= 2k+1. Equation is |x+1|-|x-1|=kx+1. I don't understand that part.
6. Originally Posted by Garas
What happened with x in -(x+1)-(-(x-1))= -2= 2k+1. Equation is |x+1|-|x-1|=kx+1. I don't understand that part.
My fault, I misread the equation! I accidently replaced the "x" with "2".
For x< -1, the left side, as I said, reduces to -2 so the equation becomes -2= kx+ 1. Now subtract 1 from each side to get kx=-3 and divide by x to get x= -3/k, as long as k is not 0. If k= 0, this gives no solution.
For -1< x< 1, the left side reduces to 2x so the equation becomes 2x= kx+ 1. subrtract kx from both sides to get 2x-kx= (2- k)x= 1 and then x= 1/(2- k) as long as k is not 2. If k= 2, this gives no solution.
For x> 1, the left side reduces to 2 so the equation becomes 2=kx+ 1. subtract 1 from both sides to get kx= 1 and divide by x to get x= 1/k, as long as k is not 0. If k= 0, ths gives no solution.
Now, what must k be so that only one of those gives a solution?
7. I solved that on the same way and it wasn't correct. The right solution is: k goes from infinity to 0 and from 1 to infinity. It's not so easy as you might thought on beginning.
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9360094666481018, "perplexity": 1623.1179019324431}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "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-2016-50/segments/1480698542714.38/warc/CC-MAIN-20161202170902-00343-ip-10-31-129-80.ec2.internal.warc.gz"}
|
http://mathhelpforum.com/calculus/73375-solved-slopes-tangents-secants.html
|
# Thread: [SOLVED] Slopes of Tangents and Secants
1. ## [SOLVED] Slopes of Tangents and Secants
Find the slope of the tangent line of the parabola 2x - x^2 at point (2,0):
So I have to use the forumla
m = lim f(a + h) - f(a) / h
h->0
So we have to find f(a) which = 0.
Then put in that to f(a + h) which = 2(0 + h) - (0+h)^2
So then you get for the equation:
(2h - 0) / h
Which would then equal 2, but the answer is -2...can anyone help?
2. Sorry it'd be (2h - h^2) on top wouldn't it? But that still doesn't work
3. Originally Posted by Dickson
Find the slope of the tangent line of the parabola 2x - x^2 at point (2,0):
So I have to use the forumla
m = lim f(a + h) - f(a) / h
h->0
So we have to find f(a) which = 0.
Then put in that to f(a + h) which = 2(0 + h) - (0+h)^2
So then you get for the equation:
(2h - 0) / h
Which would then equal 2, but the answer is -2...can anyone help?
$f(x) = 2x - x^2$
$f(2+h) = 2(2+h) - (2+h)^2$
$f(2) = 0$
$\lim_{x \to 2} \frac{f(2+h) - f(2)}{h}$
$\lim_{x \to 2} \frac{2(2+h) - (2+h)^2 - 0}{h}$
$\lim_{x \to 2} \frac{4+2h -(4 + 4h + h^2)}{h}$
$\lim_{x \to 2} \frac{4+2h -4 - 4h - h^2}{h}$
$\lim_{x \to 2} \frac{-2h - h^2}{h}$
$\lim_{x \to 2} \frac{h(-2 - h)}{h}$
$\lim_{x \to 2} (-2 - h) = -2$
4. I thought you were supposed to use the value you got from f(a) and put that in for the A value in f(a + h)
5. Originally Posted by Dickson
I thought you were supposed to use the value you got from f(a) and put that in for the A value in f(a + h)
no, it's the same "a" ... a = 2.
6. Originally Posted by skeeter
no, it's the same "a" ... a = 2.
Okay thanks a lot
|
{"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": 0, "img_math": 0, "codecogs_latex": 10, "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": 0.8706306219100952, "perplexity": 1115.416824707522}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "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-2016-44/segments/1476988719397.0/warc/CC-MAIN-20161020183839-00080-ip-10-171-6-4.ec2.internal.warc.gz"}
|
https://oneclass.com/study-guides/ca/utsc/hlt/hltb-15h3/159983-lecture10answerkeyhltb15docx.en.html
|
Study Guides (380,000)
CA (150,000)
UTSC (9,000)
# HLTB15H3 Study Guide - Rare Disease
Department
Health Studies
Course Code
HLTB15H3
Professor
Iva Zovkic
Page:
of 3
HLTB15 WINTER 2013
LECTURE # 10EPIDEMIOLOGY & STUDY DESIGNS
QUESTIONS
What is the DEFINTION of EPIDEMIOLOGY?
o The study of the distribution and determinants of health-related states in
specified populations and the application of this study to control health
problems
What is the DEFINITION of DEMOGRAPHY?
o The scientific study of human populations, including their size, composition,
distribution, density, and growth as well as the causes and socio-economic
consequences of changes in these factors.
What the different TYPES of EPIDEMIOLOGY?
o CLINICAL - internally within the body
o SOCIAL - behaviourally
o CRITICAL structurally, contextually
o COMMUNICABLE-DISEASE
o CHRONIC-DISEASE
o COMMUNITY - happens in community
o OCCUPATIONAL happens in the workplace
o QUANTITATIVE
o POPULAR/LAY
What are the TWO classes of EPIDEMIOLOGICAL STUDIES?
o EXPERIMENTAL exposure is varied to detrmien how many get the
disease, unethical
o OBSERVATIONAL occurrence of disease is observed in people who are
exposed.
What are the TWO main types of STUDY DESIGNS?
o DESCRIPTIVE disease and related factors are measure, used when
health problem is suspected and you want to develop hypotheses
o ANALYTICAL
What are the TYPES of DESCRIPTIVE STUDY DESIGNS? Describe them!
o CORRELATIONAL STUDIES: Correlational studies, data from entire
population is used, cannot link exposure to diease in the same person
o CASE REPORTS: profile of a single person
o CASE SERIES: describes the characteristics of a number of patients
o CROSS SECTIONAL STUDY exposure and disease measured at one one
point in time, survey population of interest, temporal association
cannot be clearly determined
What are the TYPES of ANALYTICAL STUDY DESIGNS?
o PROSPECTIVE COHORT idnividuals are grouped based on exposure
status and follow up to determine if exposure increases, decreases or
has no effect on the development of disease
We do it when there is STRONG suggestion of ASSOCIATION,
exposure is RARE, and there is a SHORT average time between
EXPOSURE and DISEASE
Limited to Rare Opportunities, Ascertainment of Disease
HLTB15 WINTER 2013
Advantages: Classification before the disease develops,
Calculation of incidence rates among exposed and not exposed,
Calculate risk directly, Observation of Many Outcomes, Efficient
for Rare Exposures
o HISTORICAL/RETROSPECTIVE COHORT
Cases based on exposure status, Retrspective examination,
Time of Disease Development Cannot be Ascertained, Study
Design Requires Less Time
o CASE CONTROL Selected on basis of disease
Cases Disease
Controls No Disease
Features: Cases and controls should be similar, Data
(Interviews, Employment Records, and Medical Records to
determine possible exposures)
Benefits: Rare disease, Mutliple exposures can be measured,
High effiency
o RANDOMIZED CONTROL TRIALS (RCT)
Researcher randomly assigns patients to one treatment and
other patients to a placebo, or usual treatment.
Features of RCT: Classic way to evaluate effectiveness of diverse
What are MIXED Study Designs?
o Can use both descriptive and analytical
Which type of study has KNOWN EXPOSURE?
o Cohort Study
Which type of study has KNOWN OUTCOME?
o Case-Control
What is RELATIVE RISK?
o The differential risks for different exposures
What is RELATIVE RATE RATIO?
What is RELATIVE ODDS RATIO?
How do you calculate RELATIVE RISK RATIOS?
o Incidence proportion in exposed population / Incidence proportion in
unexposed proportion = RR
What does it mean if your RELATIVE RISK RATIO is EQUAL to 1?
o No difference in incidence
What does it mean if your RELATIVE RISK RATIO is GREATER THAN to 1?
o Incidence is more in the exposed group
What does it mean if your RELATIVE RISK RATIO is LESS THAN to 1?
o Incdience is less in the exposed group
What is the PURPOSE of STANDARDIZATION OF MORTALITY RATES?
o To help control for the effects of age or other variables because for example,
young people die less often than older people. We need something to help
account and fix for that.
What are the TWO methods of STANDARDAZATION? Ajustment and
standardization refer to the procedures for facilaiting the comparison of
summary measures across group
o Remove effects of extraneous factors
o What is DIRECT STANDARDIZATION?
HLTB15 WINTER 2013
A proportion in each age group of a standard population are
applied to the age-specfic death rates of the population being
compared
o What is INDIRECT STANDARDIZATION?
A standard population is used to provide age specific death rates.
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8659759163856506, "perplexity": 9850.584718247534}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "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-2019-26/segments/1560627999800.5/warc/CC-MAIN-20190625051950-20190625073950-00253.warc.gz"}
|
http://r4ds.had.co.nz/r-markdown-formats.html
|
# 29 R Markdown formats
## 29.1 Introduction
So far you’ve seen R Markdown used to produce HTML documents. This chapter gives a brief overview of some of the many other types of output you can produce with R Markdown. There are two ways to set the output of a document:
1. Permanently, by modifying the YAML header:
title: "Viridis Demo"
output: html_document
2. Transiently, by calling rmarkdown::render() by hand:
rmarkdown::render("diamond-sizes.Rmd", output_format = "word_document")
This is useful if you want to programmatically produce multiple types of output.
RStudio’s knit button renders a file to the first format listed in its output field. You can render to additional formats by clicking the dropdown menu beside the knit button.
## 29.2 Output options
Each output format is associated with an R function. You can either write foo or pkg::foo. If you omit, pkg the default is assumed to be rmarkdown. It’s important to know the name of the function that makes the output because that’s where you get help. For example, to figure out what parameters you can set with html_document, look at ?rmarkdown::html_document
To override the default parameter values, you need to use an expanded output field. For example, if you wanted to render an html_document with a floating table of contents, you’d use:
output:
html_document:
toc: true
toc_float: true
You can even render to multiple outputs by supplying a list of formats:
output:
html_document:
toc: true
toc_float: true
pdf_document: default
Note the special syntax if you don’t want to override any of the default options.
## 29.3 Documents
The previous chapter focussed on the default html_document output. There are number of basic variations on that theme, generating different types of documents:
• pdf_document makes a PDF with LaTeX (an open source document layout system), which you’ll need to install. RStudio will prompt you if you don’t already have it.
• word_document for Microsoft Word documents (.docx).
• odt_document for OpenDocument Text documents (.odt).
• rtf_document for Rich Text Format (.rtf) documents.
• md_document for a Markdown document. This isn’t typically useful by itself, but you might use it if, for example, your corporate CMS or lab wiki uses markdown.
• github_document: this is a tailored version of md_document designed for sharing on GitHub.
Remember, when generating a document to share with decision makers, you can turn off the default display of code by setting global options in the setup chunk:
knitr::opts_chunk$set(echo = FALSE) For html_documents another option is to make the code chunks hidden by default, but visible with a click: output: html_document: code_folding: hide ## 29.4 Notebooks A notebook, html_notebook, is a variation on a html_document. The rendered outputs are very similar, but the purpose is different. A html_document is focussed on communicating with decision makers, while a notebook is focussed on collaborating with other data scientists. These different purposes lead to using the HTML output in different ways. Both HTML outputs will contain the fully rendered output, but the notebook also contains the full source code. That means you can use the .nb.html generated by the notebook in two ways: 1. You can view it in a web browser, and see the rendered output. Unlike html_document, this rendering always includes an embedded copy of the source code that generated it. 2. You can edit it in RStudio. When you open an .nb.html file, RStudio will automatically recreate .Rmd file that generated it. In the future, you will also be able include supporting files (e.g. .csv data files), which will be automatically extracted when needed. Emailing .nb.html files is a simple way to share analyses with your colleagues. But things will get painful as soon as they want to make changes. If this starts to happen, it’s a good time to learn Git and GitHub. Learning Git and GitHub is definitely painful at first, but the collaboration payoff is huge. As mentioned earlier, Git and GitHub are outside the scope of the book, but there’s one tip that’s useful if you’re already using them: use both html_notebook and github_document outputs: output: html_notebook: default github_document: default html_notebook gives you a local preview, and a file that you can share via email. github_document creates a minimal md file that you can check into git. You can easily see how the results of your analysis (not just the code) change over time, and GitHub will render it for you nicely online. ## 29.5 Presentations You can also use R Markdown to produce presentations. You get less visual control than with a tool like Keynote or PowerPoint, but automatically inserting the results of your R code into a presentation can save a huge amount of time. Presentations work by dividing your content into slides, with a new slide beginning at each first (#) or second (##) level header. You can also insert a horizontal rule (***) to create a new slide without a header. R Markdown comes with three presentations formats built-in: 1. ioslides_presentation - HTML presentation with ioslides 2. slidy_presentation - HTML presentation with W3C Slidy 3. beamer_presentation - PDF presentation with LaTeX Beamer. Two other popular formats are provided by packages: 1. revealjs::revealjs_presentation - HTML presentation with reveal.js. Requires the revealjs package. 2. rmdshower, https://github.com/MangoTheCat/rmdshower, provides a wrapper around the shower, https://github.com/shower/shower, presentation engine ## 29.6 Dashboards Dashboards are a useful way to communicate large amounts of information visually and quickly. Flexdashboard makes it particularly easy to create dashboards using R Markdown and a convention for how the headers affect the layout: • Each level 1 header (#) begins a new page in the dashboard. • Each level 2 header (##) begins a new column. • Each level 3 header (###) begins a new row. For example, you can produce this dashboard: Using this code: --- title: "Diamonds distribution dashboard" output: flexdashboard::flex_dashboard --- {r setup, include = FALSE} library(ggplot2) library(dplyr) knitr::opts_chunk$set(fig.width = 5, fig.asp = 1/3)
## Column 1
### Carat
{r}
ggplot(diamonds, aes(carat)) + geom_histogram(binwidth = 0.1)
### Cut
{r}
ggplot(diamonds, aes(cut)) + geom_bar()
### Colour
{r}
ggplot(diamonds, aes(color)) + geom_bar()
## Column 2
### The largest diamonds
{r}
diamonds %>%
arrange(desc(carat)) %>%
select(carat, cut, color, price) %>%
DT::datatable()
Flexdashboard also provides simple tools for creating sidebars, tabsets, value boxes, and gauges. To learn more about flexdashboard visit http://rmarkdown.rstudio.com/flexdashboard/.
## 29.7 Interactivity
Any HTML format (document, notebook, presentation, or dashboard) can contain interactive components.
### 29.7.1 htmlwidgets
HTML is an interactive format, and you can take advantage of that interactivity with htmlwidgets, R functions that produce interactive HTML visualisations. For example, take the leaflet map below. If you’re viewing this page on the web, you can drag the map around, zoom in and out, etc. You obviously can’t do that on a book, so rmarkdown automatically inserts a static screenshot for you.
library(leaflet)
leaflet() %>%
setView(174.764, -36.877, zoom = 16) %>%
addMarkers(174.764, -36.877, popup = "Maungawhau")
The great thing about htmlwidgets is that you don’t need to know anything about HTML or JavaScript to use them. All the details are wrapped inside the package, so you don’t need to worry about it.
There are many packages that provide htmlwidgets, including:
To learn more about htmlwidgets and see a more complete list of packages that provide them visit http://www.htmlwidgets.org/.
### 29.7.2 Shiny
htmlwidgets provide client-side interactivity — all the interactivity happens in the browser, independently of R. On one hand, that’s great because you can distribute the HTML file without any connection to R. However, that fundamentally limits what you can do to things that have been implemented in HTML and JavaScript. An alternative approach is to use shiny, a package that allows you to create interactivity using R code, not JavaScript.
To call Shiny code from an R Markdown document, add runtime: shiny to the header:
title: "Shiny Web App"
output: html_document
runtime: shiny
Then you can use the “input” functions to add interactive components to the document:
library(shiny)
numericInput("age", "How old are you?", NA, min = 0, max = 150)
You can then refer to the values with input$name and input$age, and the code that uses them will be automatically re-run whenever they change.
I can’t show you a live shiny app here because shiny interactions occur on the server-side. This means you can write interactive apps without knowing JavaScript, but it means that you need a server to run it on. This introduces a logistical issue: Shiny apps need a Shiny server to be run online. When you run shiny apps on your own computer, shiny automatically sets up a shiny server for you, but you need a public facing shiny server if you want to publish this sort of interactivity online. That’s the fundamental trade-off of shiny: you can do anything in a shiny document that you can do in R, but it that requires someone to be running R.
## 29.8 Websites
With a little additional infrastructure you can use R Markdown to generate a complete website:
• Put your .Rmd files in a single directory. index.Rmd will become the home page.
• Add a YAML file named _site.yml provides the navigation for the site. For example:
name: "my-website"
navbar:
title: "My Website"
left:
- text: "Home"
href: index.html
- text: "Viridis Colors"
href: 1-example.html
- text: "Terrain Colors"
href: 3-inline.html
Execute rmarkdown::render_site() to build _site, a directory of files ready to deploy as a standalone static website, or if you use an RStudio Project for your website directory. RStudio will add a Build tab to the IDE that you can use to build and preview your site.
|
{"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": 0.15948167443275452, "perplexity": 4287.788217839539}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "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-2017-34/segments/1502886133449.19/warc/CC-MAIN-20170824101532-20170824121532-00336.warc.gz"}
|
https://socratic.org/questions/what-is-derivatives-of-y-sec-x
|
Calculus
Topics
# What is Derivatives of y=sec(x) ?
Sep 7, 2014
$\frac{d}{\mathrm{dx}} \sec \left(x\right) = \sec \left(x\right) \tan \left(x\right)$
You could memorize this, but you can work it out too by knowing some trig properties.
The trig properties we will use are:
$\sec \left(x\right) = \frac{1}{\cos} \left(x\right)$
and $\sin \frac{x}{\cos} x = \tan x$
Deriving:
d/dx sec (x) = d/dx 1/cos(x) = (cos (x)(0) - 1 (-sin (x)))/( cos (x)cos (x)) (using the quotient rule)
= sin (x)/ (cos (x) cos (x)) = sin(x)/cos(x) *(1/cos( x)) = tan (x) sec( x)=sec (x) tan (x)
##### Impact of this question
13879 views around the world
|
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 5, "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": 0.9169480800628662, "perplexity": 26788.326822228755}, "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-2021-43/segments/1634323587767.18/warc/CC-MAIN-20211025185311-20211025215311-00080.warc.gz"}
|
https://git.trinitydesktop.org/cgit/kbibtex/tree/src/entrywidgetwarningsitem.h
|
summaryrefslogtreecommitdiffstats log msg author committer range
```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 ``` ``````/*************************************************************************** * Copyright (C) 2004-2006 by Thomas Fischer * * [email protected] * * * * This program is free software; you can redistribute it and/or modify * * it under the terms of the GNU General Public License as published by * * the Free Software Foundation; either version 2 of the License, or * * (at your option) any later version. * * * * This program is distributed in the hope that it will be useful, * * but WITHOUT ANY WARRANTY; without even the implied warranty of * * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * * GNU General Public License for more details. * * * * You should have received a copy of the GNU General Public License * * along with this program; if not, write to the * * Free Software Foundation, Inc., * * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * ***************************************************************************/ #ifndef KBIBTEXENTRYWIDGETWARNINGSITEM_H #define KBIBTEXENTRYWIDGETWARNINGSITEM_H #include class TQString; namespace KBibTeX { class EntryWidgetWarningsItem : public TQListViewItem { public: enum WarningLevel {wlInformation = 1, wlWarning = 2, wlError = 3}; EntryWidgetWarningsItem( WarningLevel level, const TQString &message, TQWidget *widget, TQListView *parent, const char* name = NULL ); ~EntryWidgetWarningsItem(); TQWidget *widget(); private: TQWidget *m_widget; }; } #endif ``````
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8556249737739563, "perplexity": 4385.366052968898}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "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-2019-22/segments/1558232259452.84/warc/CC-MAIN-20190526185417-20190526211417-00410.warc.gz"}
|
https://www.physicsforums.com/threads/question-about-solution.384965/
|
• Start date
• #1
36
0
## Homework Statement
Hello, this is the solution to a problem that i am doing and the only thing i am confused about is why the
C1 in the third step is = to − 1/2 ln 2 √3 as stated in the last line.
=√3/2 sec θ − 1/2 ln |sec θ + tanθ| + C1
that is all i am confused about but i get the rest.
i appreciate the Help Thank you very much.
• #2
Dick
Homework Helper
26,263
619
Subtract the last equation from the next to last to solve for C in terms of C1. Not that the relation between them matters very much. Either one is an arbitrary constant.
• Last Post
Replies
4
Views
382
• Last Post
Replies
3
Views
1K
• Last Post
Replies
5
Views
1K
• Last Post
Replies
1
Views
991
• Last Post
Replies
2
Views
5K
• Last Post
Replies
3
Views
2K
• Last Post
Replies
1
Views
1K
• Last Post
Replies
2
Views
1K
• Last Post
Replies
3
Views
1K
• Last Post
Replies
1
Views
1K
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9684105515480042, "perplexity": 2565.1889922300925}, "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-2022-21/segments/1652662588661.65/warc/CC-MAIN-20220525151311-20220525181311-00072.warc.gz"}
|
http://www.zazzle.com/isaac+blocks+gifts
|
Showing All Results
43 results
Related Searches: levitan, newton, de benserade
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
Got it! We won't show you this product again!
Undo
No matches for
Showing All Results
43 results
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8193805813789368, "perplexity": 4641.667793256663}, "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-2014-15/segments/1398223204388.12/warc/CC-MAIN-20140423032004-00252-ip-10-147-4-33.ec2.internal.warc.gz"}
|
https://zbmath.org/?q=an:0801.30039
|
×
# zbMATH — the first resource for mathematics
Generalized meromorphic functions. (English. Russian original) Zbl 0801.30039
Russ. Acad. Sci., Izv., Math. 42, No. 1, 133-147 (1994); translation from Izv. Ross. Akad. Nauk, Ser. Mat. 57, No. 1, 147-166 (1993).
The autor continues his pioneering work on generalized meromorphic functions on the big plane generated by a compact Abelian group $$G$$ with ordered dual group $$\Gamma\subset\mathbb{R}$$. Here he presents the proofs of several of his previously announced results. Let $$G$$ be a compact Abelian group with ordered dual group $$\Gamma\subset \mathbb{R}$$. The big plane over $$G$$ is the infinite cone $$\mathbb{C}_ \Gamma= [0,\infty)\cdot G$$, the unit big disc $$\Omega$$ over $$G$$ is the set of points $${\mathbf w}= rg$$ in the big plane whose “modulus” $$|{\mathbf w}|= r$$ is $$\leq 1$$, and $$\Omega^ 0$$ is its interior. A continuous function $$f$$ in a domain $$D\subset \mathbb{C}_ \Gamma$$ is “analytic” (generalized analytic) in $$D$$ if $$f$$ can be approximated locally by linear combinations $$\sum c(a)\backslash f(a)$$ over $$\mathbb{C}$$ of functions $$f^ a(rg)= r^ a g(a)$$, where $$r\geq 0,$$, $$g\in G$$ and $$a\in \Gamma_ +=\Gamma\cap [0,\infty)$$ in $$\mathbb{C}_ \Gamma$$.
For $$D=\Omega$$ the analyticity in this context was introduced by R. Arens and I. Singer in 1956; for an arbitrary $$D$$ the notion is due to D. Stankov and the reviewer [e.g., Big planes, boundaries and function algebras (1992; Zbl 0755.46020)]. We mention only a few of the many results in this paper.
It is given a description of the measures on $$G$$ that are orthogonal to the disc algebra of continuous up to the boundary $$G$$ generalized analytic functions on $$\Omega$$. The proof of author’s result for unique generalized analytic extension on a domain $$D\subset\Omega^ 0$$ of a bounded generalized analytic function defined on the complement in $$D$$ of a certain thin set in $$\mathbb{C}_ \Gamma$$ is presented as well.
For a class of suitably defined meromorphic functions in $$\mathbb{C}_ \Gamma$$ the following factorization result is proved.
Theorem. Let $$f$$ be a meromorphic function in $$\Omega^ 0$$ and let $$S^*\in \Omega^ 0$$ is either a removable singularity or an isolated pole. Then there is a non-vanishing generalized analytic function $$g$$ on $$\Omega^ 0$$, such that $$f\cdot g$$ can be extended to a generalized analytic function on $$\Omega^ 0$$. Versions of this result are given for the case of meromorphic functions on a “big annulus” region of type $$E^ 0=\{{\mathbf w}\in \mathbb{C}_ \Gamma< r|{\mathbf w}|< 1\}$$ and for meromorphic almost periodic functions on the upper half plane or on a horizontal strip in $$\mathbb{C}$$.
##### MSC:
30G35 Functions of hypercomplex variables and generalized variables 30D30 Meromorphic functions of one complex variable (general theory)
big plane
Full Text:
|
{"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": 1, "mathjax_asciimath": 0, "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": 0.872072696685791, "perplexity": 234.29562416627263}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "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-2021-49/segments/1637964361064.58/warc/CC-MAIN-20211201234046-20211202024046-00591.warc.gz"}
|
https://cje.ejournal.org.cn/en/article/doi/10.1049/cje.2021.00.058?viewType=HTML
|
Turn off MathJax
Article Contents
ZHANG Yi, LIU Guoqiang, SHEN Xuan, LI Chao. Rectangle Attack Against Type-I Generalized Feistel Structures[J]. Chinese Journal of Electronics. doi: 10.1049/cje.2021.00.058
Citation: ZHANG Yi, LIU Guoqiang, SHEN Xuan, LI Chao. Rectangle Attack Against Type-I Generalized Feistel Structures[J]. Chinese Journal of Electronics.
# Rectangle Attack Against Type-I Generalized Feistel Structures
##### doi: 10.1049/cje.2021.00.058
Funds: This work is supported by the National Natural Science Foundation of China (No.62172427, No.61702537, No.61772545, No.62002370), State Key Laboratory of Information Security 2020-MS-02, Scientific Research Plan of National University of Defense Technology (No.ZK21-36)
• Author Bio:
was born in 1994. He is a Ph.D. candidate of National University of Defense Technology. His research interests include design and analysis of block ciphers. (Email: [email protected])
(corresponding author) was born in 1987. He received the Ph.D. degree in Information Engineering University. His research interests include design and cryptanalysis of block ciphers. (Email: [email protected])
was born in 1990. He received the Ph.D. degree in National University of Defense Technology. His research interests include design and cryptanalysis of block ciphers. (Email: [email protected])
was born in 1966. He is a Ph.D., researcher and Ph.D. supervisor in National University of Defense Technology. His research interests include coding theory and symmetric-key cryptography. (Email: [email protected])
• Received Date: 2021-02-03
• Accepted Date: 2021-12-09
• Available Online: 2021-12-18
• Type-I Generalized Feistel Networks (GFN) are widely used frameworks in symmetric-key primitive designs such as CAST-256 and Lesamnta. Different from the extensive studies focusing on specific block cipher instances, the analysis against Type-I GFN structures gives generic security evaluation of the basic frameworks and concentrates more on the effect of linear transformation. Currently, works in this field mainly evaluate the security against impossible differential attack, zero-correlation linear attack, meet-in-the-middle attack and yoyo game attack, while its security evaluation against rectangle attack is still missing. In this paper, we filled this gap and gave the first structural analytical results of Type-I GFN against rectangle attack. We proved there exists a $(b^2-b)$ round boomerang switch for the first time, which is independent of the round functions when the GFN has $b$ branches of $m$ bits. Then we proposed a new rectangle attack model and turned the boomerang switch into chosen plaintext setting. By appending 1 more round in the beginning of the boomerang switch, we constructed a $(b^2-b+1)$ round rectangle distinguisher with probability $2^{-2(b-1)m}$, whose advantage over random permutation is $2^{m}$. Using this distinguisher, a $b^2$ round key recovery attack is performed with $2^{\frac{bm}{2}+1}$ chosen plaintexts and $(2b^{-2})2^{bm}$ encryptions.
• [1] Y. Zheng, T. Matsumoto and H. Imai, “On the Construction of Block Ciphers Provably Secure and Not Relying on Any Unproved Hypotheses,” Proc. of CRYPTO 1989, Santa Barbara, California, USA, pp.461–480, 1989. [2] N. Wang, “Security Evaluation Against Linear Cryptanalysis for a Class of Block Cipher Transform Cluster,” Acta Electronica Sinica, vol.48, no.1, pp.137–142, 2020. (in Chinese) [3] Y. Zheng and W. Wu, “Security of Khudra Against Meet-in-the-Middle-Type Cryptanalysis,” Chinese Journal of Electronics, vol.28, no.3, pp.482–488, 2019. [4] L. Cheng, B. Sun and C. Li, “Revised cryptanalysis for SMS4,” Science China Information Science, vol.60, no.12, pp.122101:1–122101:9, 2017. [5] L. Cheng and C. Li, “Revisiting impossible differentials of MARS-like structures,” IET Information Security, vol.11, no.5, pp.273–276, 2017. [6] C. Adams and J. Gilchrist, “The CAST-256 Encryption Algorithm,” Network Working Group, RFC 2612, 1999. [7] S. Hirose, H. Kuwakado and H. Yoshida, “SHA-3 Proposal: Lesamnta,” http://csrc.nist.gov/groups/ST/hash/sha-3/Round1/documents/LESAMNTA_Comments.pdf, 2008. [8] E. Biham and A. Shamir, “Differential cryptanalysis of DES-like cryptosystems,” Journal of Cryptology, vol.4, no.1, pp.3–72, 1991. [9] C. Blondeau and B. Gérard, “Multiple Differential Cryptanalysis: Theory and Practice,” Proc. of FSE 2011, Lyngby, Denmark, pp.35–54, 2011. [10] T. Cui, C. Jin and J. Ma, “A New Method for Finding Impossible Differentials of Generalized Feistel Structures,” Chinese Journal of Electronics, vol.27, no.4, pp.728–733, 2018. [11] D.A. Wagner, “The Boomerang Attack,” Proc. of FSE 1999, Rome, Italy, pp.156–170, 1999. [12] E. Biham, O. Dunkelman and N. Keller, “The Rectangle Attack – Rectangling the Serpent,” Proc. of EUROCRYPT 2001, Innsbruck, Austria, pp.340-357, 2001. [13] B. Sun, Z. Liu, V. Rijmen, et al., “Links Among Impossible Differential, Integral and Zero Correlation Linear Cryptanalysis,” Proc. of CRYPTO 2015, Santa Barbara, CA, USA, pp.95–115, 2015. [14] B. Sun, M. Liu, J. Guo, et al., “New Insights on AES-Like SPN Ciphers,” Proc. of CRYPTO 2016, Santa Barbara, CA, USA, pp.605–624, 2016. [15] T. Shirai and K. Araki, “On Generalized Feistel Structures Using the Diffusion Switching Mechanism,” IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, vol.E91-A, no.8, pp.2120–2029, 2008. [16] L. Cheng, “Cryptanalysis on Block Ciphers Structures,” Ph.D.Thesis, National University of Defense Technology, China, 2017. (in Chinese) [17] Y. Deng, C. Jin and R. Li, “Meet in the Middle Attack on Type-1 Feistel Construction,” Proc. of Inscrypt 2017, Xi'an, China, pp.427–444, 2017. [18] T. Cui, S. Chen and H. Zheng, “A Structural Attack on Type-I Generalized Feistel Networks,” IEEE Access, vol.7, pp.69304–69310, 2019. [19] B. Ni and X. Dong, “Improved Quantum Attack on Type-1 Generalized Feistel Schemes and Its Application to CAST-256,” Journal of Electronics & Information Technology, vol.42, no.2, pp.295–306, 2020. (in Chinese) [20] E. Biham, O. Dunkelman and N. Keller, “A Related-Key Rectangle Attack on the Full KASUMI,” Proc. of ASIACRYPT 2005, Chennai, India, pp.443–461, 2005. [21] H. Hadipour, N. Bagheri and L. Song, “Improved Rectangle Attacks on SKINNY and CRAFT,” IACR Transactions on Symmetric Cryptology, vol.2021, no.2, pp.140–198, 2021. [22] S. Murphy, “The return of the cryptographic boomerang,” IEEE Transactions on Information Theory, vol.57, no.4, pp.2517–2521, 2011. [23] A. Biryukov and D. Khovratovich, “Related-key cryptanalysis of the full AES-192 and AES-256,” Proc. of ASIACRYPT 2009, Tokyo, Japan, pp.1-18, 2009. [24] C. Cid, T. Huang, T. Peyrin, et al., “Boomerang connectivity table: A new cryptanalysis tool,” Proc. of EUROCRYPT 2018, Tel Aviv, Israel, pp.683-714, 2018. [25] K. Li, L. Qu, B. Sun, et al., “New Results About the Boomerang Uniformity of Permutation Polynomials,” IEEE Transactions on Information Theory, vol.65, no.11, pp.7542–7553, 2019. [26] H. Wang and T. Peyrin, “Boomerang switch in multiple rounds,” IACR Transactions on Symmetric Cryptology, vol.2019, no.1, pp.142–169, 2019. [27] L. Song, X. Qin and L. Hu, “Boomerang connectivity table revisited,” IACR Transactions on Symmetric Cryptology, vol.2019, no.1, pp.118–141, 2019. [28] H. Boukerrou, P. Huynh, V. Lallemand, et al., “On the Feistel Counterpart of the Boomerang Connectivity Table Introduction and Analysis of the FBCT,” IACR Transactions on Symmetric Cryptology, vol.2020, no.1, pp.331–362, 2020. [29] Z. Niu, “The Study of Modulo $2^n$,” https://eprint.iacr.org/2021/056, 2021. [30] J. Kelsey, T. Kohno and B. Schneier, “Amplified Boomerang Attacks Against Reduced-Round MARS and Serpent,” Proc. of FSE 2000, New York, NY, USA, pp.75-93, 2000. [31] J. Kim, S. Hong, B. Preneel, et al., “Related-Key Boomerang and Rectangle Attacks: Theory and Experimental Analysis,” IEEE Transactions on Information Theory, vol.58, no.7, pp.4948–4966, 2012. [32] S. Tian, C. Boura and L. Perrin, “Boomerang uniformity of popular S-box constructions,” Designs, Codes and Cryptography, vol.88, no.9, pp.1959–1989, 2020.
### Catalog
###### 通讯作者: 陈斌, [email protected]
• 1.
沈阳化工大学材料科学与工程学院 沈阳 110142
Figures(6) / Tables(1)
## Article Metrics
Article views (84) PDF downloads(17) Cited by()
/
|
{"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": 0, "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": 0.6006057262420654, "perplexity": 13073.484932150059}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "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-2022-27/segments/1656103355949.26/warc/CC-MAIN-20220628050721-20220628080721-00482.warc.gz"}
|
https://www.arxiv-vanity.com/papers/0910.5477/
|
# Non-commutative Donaldson-Thomas theory and vertex operators
Kentaro Nagao
RIMS, Kyoto University
Kyoto 606-8502, Japan
###### Abstract
In [Nagb], we introduced a variant of non-commutative Donaldson-Thomas theory in a combinatorial way, which is related to the topological vertex by a wall-crossing phenomenon. In this paper, we (1) provide an alternative definition in a geometric way, (2) show that the two definitions agree with each other and (3) compute the invariants using the vertex operator method, following [ORV06] and [BY10]. The stability parameter in the geometric definition determines the order of the vertex operators and hence we can understand the wall-crossing formula in non-commutative Donaldson-Thomas theory as the commutator relation of the vertex operators.
\excludeversion
NB
## Introduction
Let be a affine toric Calabi-Yau -fold, which corresponds to the trapezoid with height 1, with length edge at the top and at the bottom. Let be a crepant resolution of . Note that has affine lines as torus invariant closed subvarieties (). In other words, there are open edges in the toric graph of . Given an -tuple of Young diagrams
(ν––,λ––)=(ν+,ν−,λ(1/2),…,λ(L−1/2))(L:=L++L−)
associated with open edges (see Figure 3), we can define a torus invariant ideal sheaf on 2.1) and a moduli space of quotient sheaves of 4.1). Note that and hence the moduli space is the Hilbert scheme of closed subschemes of . We define Euler characteristic version of open (commutative) Donaldson-Thomas invariants by the Euler characteristics of the connected components of 111The word “open” stems from such terminologies as “open topological string theory”. According to [AKMV05], open topological string partition function is given by summing up the generating functions of these invariants over Young diagrams.. The torus action of induces the torus action on . The torus fixed point set is isolated and parametrized in terms of -tuples of -dimensional Young diagrams. Thus the generating function of the open Donaldson-Thomas invariants can be described in terms of topological vertex ([AKMV05, MNOP06], see §4.2).
Let be a non-commutative crepant resolution of the affine toric Calabi-Yau -fold . We can identify the derived category of coherent sheaves on and the one of -modules by a derived equivalence. A parameter gives a Bridgeland’s stability condition of this derived category, and hence a core of a t-structure on it (Definition 1.12). In fact, we have two specific parameters such that the corresponding t-structures coincide with the ones given by or respectively. Given an element in , we can restrict it to get a sheaf on the smooth locus . Since the singular locus is compact, it makes sense to study those elements in which are isomorphic to outside a compact subset of , or in other words, those elements in which have the same asymptotic behavior as . We will study the moduli spaces of such objects as noncommutative analogues of . NB. We want to study moduli spaces
of pairs of finite dimensional -modules and morphisms in the derived category 222Let denote the cohomology with respect to the t-structure corresponding to . Since the derived equivalence is given by a tilting, we have unless . In particular, giving a morphism is equivalent to giving a morphism . . In general the ideal sheaf is not an element in , however is always in . We will construct the moduli space of quotients of in as a GIT quotient (§5.1). Note that is the moduli space we have studied in [Naga]. We define Euler characteristic version of open non-commutative Donaldson-Thomas invariants by the Euler characteristics of the connected components of 333The reader may also refer to [NY] in which we study the invariants in the physics context..
NB. In order to compute the invariants, we will give another description of the moduli space. Given , we can construct a core of a t-structure of the derived category and an element in . We define
M(ν––,λ––,ζ):={Pζν––,λ––↠F∣F∈Aζfin}.
Then we have a natural isomorphism between and . The torus action on induces a torus action on the moduli . We will compute the Euler characteristic by counting the number of torus fixed points. For a generic , the core of the t-structure is isomorphic to the category of -modules, where is associated with a quiver with a potential. Hence, we can describe the torus fixed point set on in terms of a crystal melting model ([ORV06, OY09]), which we have studied in [Nagb]. In fact, a particle in the grand state crystal gives a weight vector in with respect to the torus action, and a crystal obtained by removing a finite number of particles from the grand state crystal gives a torus fixed point in 3.1). The invariants in this paper agree with the ones defined in [Nagb].
Finally, we provide explicit formulas for the generating functions of the Euler characteristic version of the open commutative and non-commutative Donaldson-Thomas invariants using vertex operator method, following [ORV06], [BY10] and [BCY]444During preparing this paper, the author was informed that Piotr Sulkowski and Benjamin Young provide similar computations independently ([Sul, You]). . The order of the vertex operators is determined by the chamber in which the parameter is. Hence we can understand the wall-crossing formula as the commutator relation of the vertex operators.
In Szendroi’s original non-commutative Donaldson-Thomas theory ([Sze08]) the moduli spaces admit symmetric obstruction theory and the invariants are defined as the virtual counting of the moduli spaces in the sense of Behrend-Fantechi ([BF97])555Virtual counting coincides with the weighted Euler characteristic weighted by the Behrend function.. In the case when , we show that the moduli space admits a symmetric obstruction theory (§5.2). Using the result in [BF08], we can verify that the virtual counting coincide with the (non-weighted) Euler characteristics up to signs as in [Sze08, MR10, NN, Naga]6.1). We can also compute the generating function of the weighted (or non-weighted) Euler characteristics using Joyce-Song’s theory ([JS], or [Joy08]).
The plan of this paper is as follows: Section 1 contains basic observations on the core of the t-structure of the derived category. In Section 2, the definition of Euler characteristic version of open non-commutative Donaldson-Thomas invariants is provided. Then, we compute the generating function using vertex operators in Section 3. Finally, we study open Donaldson-Thomas invariants and topological vertex as “limits” of open non-commutative Donaldson-Thomas invariants in Section 4. Section 2, Section 3 and Section 4 are the main parts of this paper. In Section 5 we construct the moduli spaces used in Section 2 and 4 to define invariants. Moreover, we construct symmetric obstruction theory on the moduli space in the case of in Section 5.2. The relation between weighted Euler characteristic and Euler characteristic is discussed in Section 6.1. Throughout this paper we work on the half of the whole space of stability parameters. We will have a discussion about the other half of the stability space in Section 6.2. The computation in Section 3 depends on an explicit combinatorial description of the derived equivalence. We leave it until Section 6.4 since it is very technical.
### Acknowledgement
The author is supported by JSPS Fellowships for Young Scientists (No. 19-2672). He thanks to Jim Bryan for letting him know the result of [BCY] and recommending him to apply the vertex operator method in the setting of this paper. He also thanks to Osamu Iyama, Hiroaki Kanno, Hiraku Nakajima, Piotr Sulkowski, Yukinobu Toda, Masahito Yamazaki and Benjamin Young for useful comments.
This paper was written while the author is visiting the University of Oxford. He is grateful to Dominic Joyce for the invitation and to the Mathematical Institute for hospitality.
## Notations
Let denote the set of half integers and be a positive integer. We set and . The two natural projections and are denoted by the same symbol . We sometimes identify and with and respectively. The symbols , , and are used for elements in , , and respectively.
Throughout this paper, the following data play crucial roles:
• a map , which determines the crepant resolution and the non-commutative crepant resolution ,
• a pair of Young diagram and an -tuple of Young diagrams , which determines the “asymptotic behaviors” of (complexes of) sheaves we will count,
• a stability parameter , which determines the t-structure where we will work on, and
• a bijection , which determines the chamber where the stability parameter is.
We sometimes identify a Young diagram with a map such that for and for 666Such a map is called a Maya diagram. See, for example, [Nag09, §2] for the correspondence between a Young diagram and a Maya diagram.. We identify an -tuple of Young diagrams with a map by
λ––(h)=λ(π(h))(h−π(h)L+12).
We define the following categories:
: the Abelian category of coherent sheaves on ,
: the full subcategory of consisting of coherent sheaves with compact supports,
: the bounded derived category ,
: the full subcategory of consisting of complexes with compactly supported cohomologies,
: the Abelian category of finitely generated left -modules,
: the full subcategory of consisting of finite dimensional modules,
: the bounded derived category of ,
: the full subcategory of consisting of complexes with finite dimensional cohomologies.
## 1 T-structure and chamber structure
### 1.1 Non-commutative and commutative crepant resolutions
Let be a map from to . In [Naga], following [HV07], we introduced a quiver with a potential , which is a non-commutative crepant resolution of ([Naga]). First, we set
H(σ) S(σ) :={n∈Z∣σ(n−1/2)≠σ(n+1/2)},IS(σ):=π(S(σ)).
The symbol and represent “hexagon” and “square” respectively. We use such notations since an element in each set corresponds to a hexagon or square in the dimer model (see [Naga, §1.2]). The vertices of are parametrized by and the arrows are given by
Here (resp. ) is an edge from to (resp. from to ) and is an edge from to itself. See [Naga, §1.2] for the definition of the potential . NB.
###### Example 1.1.
In Figure 1, we show the quiver for as in Example LABEL:ex2.
###### Remark 1.2.
• The center of is isomorphic to . In [Naga, Theorem 1.14 and 1.19], we showed that is a non-commutative crepant resolution of .
• The affine -fold is toric. In fact,
T=Spec~R:=SpecC[x±,y±,z±,w±]/(xy=zL+wL−)
is a -dimensional torus. The torus acts on by
Let (resp. ) be the projective (resp. simple) -module corresponding to the vertex . Let be the numerical Grothendieck group of , which we identify with by the natural basis . We put .
We identity the dual space with by the dual basis of . Take .
###### Theorem 1.3 ([IUb]).
The moduli space of -stable ( -semistable) -modules with dimension vectors gives a crepant resolution of .
Let denote this crepant resolution.
###### Theorem 1.4 ([Naga, §1]777It is known by [Moz, Boc] that a quiver with a potential given from a brane tiling satisfying the “consistency condition” ([Mr10, Dav, Bro, IUa]) is a non-commutative crepant resolution over its center ([VdB]). The claim of this theorem is a little bit stronger, i.e. Aσ is given by the construction in [VdB04] and hence we have −1Per(Y/X)≃modAσ. We will use this equivalence of the Abelian categories in Section 4., see §4.1).
We have a derived equivalence between and , which restricts to an equivalence between (resp. ) and (resp. ).
### 1.2 Stability condition and tilting
For such that , we define the group homomorphism
Zζ∘:Knum(modfinAσ)→C
by
Zζ∘(v):=(−ζ∘+η√−1)⋅v
where . Then gives a stability condition on in the sense of Bridgeland ([Bri07]).
For a pair of real numbers , let be the full subcategory of consisting of elements whose Harder-Narasimhan factors have phases less or equal to and larger than . The following claims are standard (see [Bri07]):
###### Lemma 1.5.
(1) where represents the shift in the derived category.
(2) is a core of a t-structure for any .
(3) .
(4) For , the pair of subcategories
(Dζ∘fin[t,s),Dζ∘fin[s,t−1))
gives a torsion pair ([Bri05, Definition 2.4]) for the Abelian category .
(5) For , is obtained from by tilting with respect to the torsion pair above ([HRS96], [Bri05, Proposition 2.5]), i.e.
Dζ∘fin[s,s−1)= {E∈Dbfin(modAσ)∣∣H0Dζ∘fin[t,t−1)(E)∈Dζ∘fin[s,t−1), H1Dζ∘fin[t,t−1)(E)∈Dζ∘fin[t,s)}, Dζ∘fin[t,t−1)= {E∈Dbfin(modAσ)∣∣H0Dζ∘fin[s,s−1)(E)∈Dζ∘fin[s,t−1), H−1Dζ∘fin[s,s−1)(E)∈Dζ∘fin[t−1,s−1)},
where represents the cohomology with respect to the t-structure corresponding to .
###### Lemma 1.6.
The algebra is (left-)Noetherian.
###### Proof..
In [Naga], it is shown that is isomorphic to for a vector bundle on , where is the contraction . Since is proper, is finitely generated as an -module. Hence is Noetherian. ∎
###### Proposition 1.7.
For we put
Dζ∘fin[1,t)⊥:={E∈modAσ∣HomAσ(F,E)=0,∀F∈Dζ∘fin[1,t)}.
Then the pair of full subcategory gives a torsion pair in .
###### Proof..
We will prove that every object fits into a short exact sequence
0→E→F→G→0
for some pair of objects and .
By Lemma 1.6, has the maximal finite dimensional submodule . Let denote the cokernel of the inclusion . Note that for any finite dimensional -module .
Let
0→F(3)→F(1)→F(4)→0
be the exact sequence such that and .Note that for any we have .
Let denote the cokernel of the inclusion . Then we have the following exact sequence:
0→F(4)→F(5)→F(2)→0.
This implies for any . Put and , then the claim follows. ∎
NB.
###### Lemma 1.8.
The natural inclusion has a right adjoint.
###### Proof..
Since is Noetherian, an element has the maximal finite dimensional submodule . The functor gives a right adjoint of the inclusion. ∎
A right admissible subcategory of is a full subcategory such that the inclusion functor has a right adjoint ([bridgeland-flop, Definition 2.1]).
###### Corollary 1.9.
For , is a right admissible full subcategory of .
###### Definition 1.10.
For let denote the core of the t-structure given from by tilting with respect to the torsion pair in Proposition 1.7, i.e.
Dζ∘[t,t−1)={E∈Db(modAσ)∣∣H0modAσ(E)∈Dζ∘[t,0), H1modAσ(E)∈Dζ∘[1,t)}.
NB. The following lemma is also easy to verify:
###### Lemma 1.11.
Let be a distinguished triangle in and for . Then, the triangle gives an exact sequence in if and only if it gives an exact sequence in . In particular, in such a case we have .
I’m not sure that the following is true. Moreover, have a torsion pair
for the Abelian category such that
Dζ∘[0,t)∩modfinAσ=Dζ∘fin[0,t),Dζ∘[t,1)∩modfinAσ=Dζ∘fin[t,1).
Let be the Abelian category given by tilting.
We have the following bijection:
{(ζ∘,T)∣ζ∘⋅δ=0, T∈R}∼⟶RI≃(Knum(modfinAσ)⊗R)∗(ζ∘,T)⟼ζ∘−Tη.
The inverse map is given by
T:=−ζ⋅η/L,ζ∘:=ζ+Tη
for . For a fixed , take such that . Note that for an element we have
ϕZζ∘(V)
where .
###### Definition 1.12.
Aζfin:=Dζ∘fin[t,t−1),Aζ:=Dζ∘[t,t−1).
NB.
###### Remark 1.13.
We have the natural action of on the space of Bridgeland’s stability conditions given by rotation of the complex line which is the target of the central charge. We can embed into the space of Bridgeland’s stability conditions by
ζ↦Zζ:=rott(Zζ∘).
Note that agrees with . This is the reason why we call a stability parameter, although we will use the former description since it is more convenient in our argument.
### 1.3 Chamber structure
A stability parameter is said to be generic if there is no -semistable objects with phase . Then we get a chamber structure in .
###### Proposition 1.14.
The chamber structure coincides with the affine root chamber structure of type .
###### Proof..
A -semistable object has the phase if and only if and so the genericity in this paper agrees with the one in [Naga]. Then the claim follows from [Naga, Proposition 2.10, Corollary 2.12]. ∎
Here we give a brief review for the affine root system of type . We call the root lattice and a simple root. For , we define by
α[h,h′]:=⎧⎪⎨⎪⎩0h=h′,απ(h+1/2)+⋯+απ(h′−1/2)hh′
and . We set
Λ:={α[h,h′]∣h≠h′},Λ+:={α[h,h′]∣hh′}
and
Λre:={α[h,h′]∣h≢h′(modL)},Λim:={mδ∣m≠0}.
An element in (resp. , , , ) is called a root (resp. positive root, negative root, real root, imaginary root). Note that . We put and define , and in the same way.
For a root , let denote the hyperplane in given by
Wα:={ζ∈(Knum(modfinAσ)⊗R)∗∣ζ⋅α=0}.
The walls in the affine root chamber structure of type is given by
Wδ∪⋃α∈Λre,+Wα.
Throughout this paper, we work on the area below the wall , i.e. on the area .
### 1.4 Parametrization of chambers
Let denote the set of bijections such that
• for any , and
• .
We have a natural bijection between and the set of chambers in the area . An element in the chamber corresponding to satisfies the following condition:
α[h,h′]⋅ζθ<0⟺θ(h)<θ(h′)
for any . For and , we define by
α(θ,i):=α[θ(n−1/2),θ(n+1/2)](π(n)=i).
Then the chamber is adjacent to the walls and we have for .
Let be the bijection given by
θi(h)=⎧⎨⎩h+1π(h+1/2)=i,h−1π(h−1/2)=i,hotherwise.
Then we have and the chambers and are separated by the wall .
### 1.5 Mutation
Assume that and is such that is not on an intersection of two walls for any . Let () be the set of all the parameters such that is not generic. According to the argument at the end of the previous subsection, we have the sequence of elements in such that for any is on the wall for
αr:=α(θi1∘⋯∘θir−1,ir).
Take the minimal positive integer such that and put . Using this notation we have the following equivalencies of the Abelian categories:
###### Proposition 1.15.
Aζfin≃modfinAζσ,Aζ≃modAζσ.
###### Proof..
We have the derived equivalence between and obtained by the tilting generator as in [Naga, Proposition 3.1]. It is easy to see that, under this equivalence, the module category of is obtained from the one of by tilting with respect to the torsion pair obtained by the simple module.
Combine with the descriptions in §1.2, we can see the claim by induction with respect to . ∎
Let be the simple -module associated to the vertex . For , we have
[Sζi]=α(θ,i)∈Knum(modfinAσ) (1.2)
under the induced isomorphism
Knum(modfinAσ)≃Knum(modfinAζσ),
NB. We put
Aζ:=modAζσ.
This is obtained from by tilting with respect to the right (left?) admissible subcategory
Dζ∘fin[1,t)⊂modfinAσ⊂modAσ.
NB. We say is generic if does not on an intersection of two chambers for any . Let be the set of all the parameter such that is not generic. Let be the real root such that is on the wall .
###### Proposition 1.16.
There exist a sequence of elements in such that
αr=ϕi1⋯ϕir−1αir.
###### Proof..
We can take inductively. Assume that () is in a chamber surrounded by walls corresponding to
ϕi1⋯ϕir−1αi(i∈I)
and is on the wall corresponding to
ϕi1⋯ϕir−1αir.
Then we can verify that () is in a chamber surrounded by walls corresponding to
ϕi1⋯ϕirαi(i∈I).
## 2 Definition of the invariants
### 2.1 Ideal sheaf associated to Young diagrams
In this paper, we regard a Young diagram as a subset of . For a Young diagram , let (resp. or ) be the subset of consisting of the elements such that (resp. or ). Given a triple of Young diagrams, let be the following subset of :
Λmin:=Λx(λx)∪Λy(λy)∪Λz(λz)⊂(Z>0)3.
A subset of is said to be a -dimensional Young diagram of type if the following conditions are satisfied:
• if , then ,
• , and
• .
For a -dimensional Young diagram
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9842957854270935, "perplexity": 569.0057843155957}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "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-2021-10/segments/1614178369553.75/warc/CC-MAIN-20210304235759-20210305025759-00449.warc.gz"}
|
https://tlovering.wordpress.com/2011/11/01/zeta-functions-of-varieties-over-a-finite-field/
|
In this short post we look at the general definition of a zeta function for a scheme of finite type over ${Spec {\mathbb Z}}$ and record its relationship with the zeta function of an algebraic variety ${X}$ over a finite field ${\mathbb{F}_q}$, defined as a kind of generating function for the number of points of ${X}$ over all finite extensions of ${\mathbb{F}_q}$.
Let ${X}$ be a scheme of finite type over ${Spec {\mathbb Z}}$. In fact, for concreteness, we start by looking at a single affine chart: imagining ${X=Spec A}$ as a geometrical space whose ring ${A}$ of functions is a quotient of some ring ${{\mathbb Z}[t_1,...,t_n]}$ of polynomials (in finitely many variables).
Then for every maximal ideal ${m}$ of ${A}$, the quotient ${A/m}$ is in fact a finite field, so we can define the norm ${N_m = |A/m|}$ to get a positive integer ${\geq 2}$ associated with ${m}$. We can use this to define the zeta function associated with ${X}$ to be the following formal Dirichlet series, by analogy with the classical Euler product formula.
$\displaystyle \zeta_X(s) = \prod_{m \text{ a maximal ideal of }A} \frac{1}{1-N_m^{-s}}.$
Notice that taking ${X=Spec {\mathbb Z}}$ we recover the classical Riemann zeta function, and taking the ring of integers of a number field recovers the zeta function of a number field. What happens if we take ${X}$ to be a variety over a finite field ${\mathbb{F}_q}$?
Well, ${log \zeta_X(s) = - \sum_{x} log(1-N_x^{-s})}$ where the sum is over all closed points ${x \in X}$.
What is a closed point of ${X}$? What is an ${\mathbb{F}_{q^r}}$-rational point of ${X}$? This is one of the confusing subtleties of scheme theory: these concepts are related but not exactly the same. Since the more classical definition of a zeta function is in terms of rational points, we will have to make this leap.
In fact, an ${\mathbb{F}_{q^r}}$-rational point (which we will also call a geometric point’, perhaps slightly nonstandardly) is simply a map ${Spec(\mathbb{F}_{q^r}) \rightarrow X}$. This makes sense for two reasons. Firstly, a point in ordinary geometry can be described as just a map from a one point space (or as a zero-simplex, if you like), so our definition seems plausible. Secondly, and more convincingly, in the case where ${X}$ is affine, for example the elliptic curve over ${{\mathbb Z}}$, ${y^2=x^3-x}$, such a map corresponds to a map of rings
$\displaystyle {\mathbb Z}[x,y]/(y^2-x^3+x) \rightarrow \mathbb{F}_{q^r}.$
In other words, it corresponds to a choice of values for ${x}$ and ${y}$ in ${\mathbb{F}_{q^r}}$ satisfying the governing equation – exactly what we should mean by specifying a ${\mathbb{F}_{q^r}}$-rational point.
On the other hand, a closed point is a maximal ideal of the ring of functions of an affine neighbourhood. Whenever we have a map ${Spec\mathbb{F}_{q^r} \rightarrow X}$, it corresponds to a map of rings whose image is a field. In other words, a map whose kernel is a maximal ideal. Therefore, every ${\mathbb{F}_{q^r}}$-rational point is associated with a unique closed point ${x}$. In fact, we get an induced map ${k(x) \rightarrow \mathbb{F}_{q^r}}$, where ${k(x)}$ is the residue field at ${x}$. Conversely, any such map can be extended and determines a geometric point.
So finally we have arrived at the relationship between closed points and geometric points. Namely, each closed point ${x}$ determines the a set of ${\mathbb{F}_{q^r}}$-rational points ${X_x}$ which can be canonically identified with ${Hom_{\mathbb{F}_q}(k(x), \mathbb{F}_{q^r})}$. But by basic Galois theory, this says that, if ${|k(x)|=q^d}$, ${X_x}$ is nonempty iff ${d|r}$, in which case ${|X_x|=d}$.
So let us return to our zeta function. Writing ${N_x=q^d}$, we can expand
$\displaystyle -log(1-N_x^{-s}) = \sum_{m \geq 1} \frac{q^{-sdm}}{m}.$
Now, set ${T=q^{-s}}$ and bearing in mind where we are trying to get (to an expression involving the numbers ${|X_x|}$), we can define ${N(m,x)}$ to be ${d}$ if ${d|m}$ and ${0}$ otherwise, and rewrite this sum as
$\displaystyle \sum_{m \geq 1} N(m,x)\frac{T^m}{m} = \sum_{m \geq 1} |Hom_{\mathbb{F}_q}(k(x), \mathbb{F}_{q^r})|\frac{T^m}{m}.$
Now, take the sum over all closed points ${x}$, and conclude that
$\displaystyle log \zeta_X(s) = \sum_{m \geq 1} (\sum_x |Hom_{\mathbb{F}_q}(k(x), \mathbb{F}_{q^r})|)\frac{T^m}{m} = \sum_{m \geq 1} |X(\mathbb{F}_{q^m})|\frac{T^m}{m}.$
This gives the familiar expression for the zeta function as an object whose logarithmic derivative is a generating function for the number of points of ${X}$ over all the finite field extensions of ${\mathbb{F}_q}$, as appears in the statement of the Weil Conjectures and is well studied. One can check further that given the analysis above, the Riemann Hypothesis’ for varieties of dimension ${d}$ over a finite field asserts that all the zeroes are on the lines ${Re(s) = 1/2,3/2,....,(2d-1)/2}$ and the poles are on the lines ${Re(s) = 0,1,2,...,d}$. Noting that ${{\mathbb Z}}$ is an object of dimension 1, the analogy with the classical Riemann hypothesis could not be clearer.
|
{"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": 67, "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": 0.9655256271362305, "perplexity": 68.48124430704227}, "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-2018-05/segments/1516084886437.0/warc/CC-MAIN-20180116144951-20180116164951-00617.warc.gz"}
|
https://anhngq.wordpress.com/2009/08/01/solutions-of-equations-in-one-variable/
|
# Ngô Quốc Anh
## August 1, 2009
### Solutions of Equations in One Variable
A root-finding algorithm is a numerical method, or algorithm, for finding a value $x$ such that $f(x) = 0$, for a given function $f$. Such an $x$ is called a root of the function $f$.
Suppose $f$ is a continuous function defined on the interval $[a, b]$, with $f(a)$ and $f(b)$ of opposite sign. By the Intermediate Value Theorem, there exists a number $p$ in $(a, b)$ with $f(p) = 0$. Although the procedure will work when there is more than one root in the interval $(a,b)$, we assume for simplicity that the root in this interval is unique. The method calls for a repeated halving of subintervals of $[a, b]$ and, at each step, locating the half containing $p$.
To begin, set $a_1=a$ and $b_1=b$, and let $p_1$ be the midpoint of $[a,b]$; that is,
$\displaystyle p_1 = a_1 + \frac{b_1-a_1}{2}=\frac{a_1+b_1}{2}$.
If $f(p_1)=0$, then $p=p_1$, and we are done. If $f(p_1)\ne 0$, then $f(p_1)$ has the same sign as either $f(a_1)$ or $f(b_1)$. When $f(p_1)$ and $f(a_1)$ have the same sign, $p \in (p_1, b_1)$, and we set $a_2=p_1$ and $b_2 = b_1$. When $f(p_1)$ and $f(a_1)$ have opposite signs, $p \in (a_1, p_1)$, and we set $a_2 = a_1$ and $b_2 = p_1$. We then reapply the process to the interval $[a_2, b_2]$.
A number p is a fixed point for a given function g if $g(p) = p$. In this section we consider the problem of finding solutions to fixed-point problems and the connection between the fixed-point problems and the root-finding problems we wish to solve. Root-finding problems and fixed-point problems are equivalent classes in the following sense:
Given a root-finding problem $f(p) = 0$, we can define functions $g$ with a fixed point at $p$ in a number of ways, for example, as $g(x) = x-f(x)$ or as $g(x) = x + 3f(x)$. Conversely, if the function $g$ has a fixed point at $p$, then the function defined by $f(x) = x-g(x)$ has a zero at $p$.
Although the problems we wish to solve are in the root-finding form, the fixed-point form is easier to analyze, and certain fixed-point choices lead to very powerful root-finding techniques.
• Newton’s method
Newton’s (or the Newton-Raphson) method is one of the most powerful and well-known numerical methods for solving aroot-finding problem. With an initial approximation $p_0$, the Newton’s method generates the sequence $\{p_n\}_{n=1}^\infty$ by
$\displaystyle {p_{n + 1}} = {p_n} - \frac{{f\left( {{p_n}} \right)}} {{f'\left( {{p_n}} \right)}}, \quad n \geqslant 0$.
To circumvent the problem of the derivative evaluation in Newton’s method, we introduce a slight variation. By definition,
$\displaystyle f'(x) = \mathop {\lim }\limits_{x \to {p_n}} \frac{{f(x) - f({p_{n - 1}}){\text{ }}}}{{x - {p_{n - 1}}}}$.
Letting $x=p_{n-1}$, we have
$\displaystyle f'\left( {{p_n}} \right) \approx \frac{{f\left( {{p_{n - 1}}} \right) - f\left( {{p_n}} \right)}} {{{p_{n - 1}} - {p_n}}}$
which yields
$\displaystyle {p_{n + 1}} = {p_n} - {\text{ }}\frac{{f({p_n})\left( {{p_{n - 1}} - {p_n}} \right)}}{{f({p_{n - 1}}) - f({p_{n - 2}})}}$.
• The method of False Position
The method of False Position (also called Regula Falsi) generates approximations in the same manner as the Secant method, but it includes a test to ensure that the root is bracketed between successive iterations. Although it is not a method we generally recommend, it illustrates how bracketing can be incorporated.
First choose initial approximations $p_0$ and $p_1$ with $f(p_0) f(p_1) < 0$. The approximation $p_2$ is chosen in the same manner as in the Secant method, as the $x$-intercept of the line joining $(p_0, f(p_0))$ and $(p_1, f(p_1))$. To decide which secant line to use to compute $p_3$, we check $f(p_2) f(p_1)$. If this value is negative, then $p_1$ and $p_2$ bracket a root, and we choose $p_3$ as the $x$-intercept of the line joining $(p_1, f(p_1))$ and $(p_2, f(p_2))$. If not, we choose $p_3$ as the $x$-intercept of the line joining $(p_0, f(p_0))$ and $(p_2, f(p_2))$, and then interchange the indices on $p_0$ and $p_1$.
In a similar manner, once $p_3$ is found, the sign of $f(p_3)f(p_2)$ determines whether we use $p_2$ and $p_3$ or $p_3$ and $p_1$ to compute $p_4$. In the latter case a relabeling of $p_2$ and $p_1$ is performed.
Source: Richard L. Burden and J. Douglas Faires, Numerical Analysis, 8th edition, Thomson/Brooks/Cole, 2005.
|
{"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": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 84, "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": 0.9701528549194336, "perplexity": 111.11944087663261}, "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/1498128320395.62/warc/CC-MAIN-20170625032210-20170625052210-00450.warc.gz"}
|
http://www.zentralblatt-math.org/ioport/en/?q=au:Salva%2C%20N*
|
History
Please fill in your query. A complete syntax description you will find on the General Help page.
Simultaneous determination of unknown coefficients through a phase-change process with temperature-dependent thermal conductivity. (English)
JP J. Heat Mass Transf. 5, No. 1, 11-39 (2011).
Summary: Formulas are obtained for the simultaneous determination of two or three unknown thermal coefficients of a semi-infinite material with temperature-dependent thermal conductivity through a phase-change process with an over-specified condition on the fixed face through a moving boundary problem (inverse Stefan problem) or a free boundary problem (Stefan problem), respectively. We complete and improve the analysis done in [the second author, “The determination of unknown thermal coefficients through phase change process with temperature-dependent thermal conductivity", Int. Commun. Heat Mass Transfer 25, No.~1, 139‒147 (1998), \url{doi:10.1016/S0735-1933(97)00145-0}] and we also study the sensitivity of the solution depending on different thermal parameters, applied to aluminium.
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8550733327865601, "perplexity": 2412.3903785365765}, "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-2013-20/segments/1368698958430/warc/CC-MAIN-20130516100918-00094-ip-10-60-113-184.ec2.internal.warc.gz"}
|
https://tohoku.pure.elsevier.com/en/publications/experimental-evaluation-of-thermal-radiation-effects-on-natural-c
|
# Experimental evaluation of thermal radiation effects on natural convection with a Rayleigh number of 108–109 by using an interferometer
Takuma Kogawa, Eita Shoji, Junnosuke Okajima, Atsuki Komiya, Shigenao Maruyama
Research output: Contribution to journalArticlepeer-review
5 Citations (Scopus)
## Abstract
In this study, the radiation effects on the temperature field and perturbation of the thermal boundary layer of natural convection for gas were evaluated by an interferometer. The natural convection investigated in this study was that of a cavity, which had differentially heated vertical walls, surrounded by adiabatic walls. The target Rayleigh number was of the order of 108–109. By using the interferometer adopted in a phase-shifting technique, surface and gas radiation effects were evaluated. To compare the experimental results, a numerical calculation was also conducted using a large-eddy simulation coupled with radiative heat transfer. By varying the emissivity of the adiabatic walls while maintaining the emissivity of the isothermal walls, the surface radiation effect on the natural convection was analyzed. To neglect the gas radiation effect, air was used as the working fluid. When the adiabatic walls were black-body surfaces, the temperature difference around the adiabatic walls was higher than that of the reflective surface as a result of the optical path difference. From this result, the high temperature difference due to the surface radiation effect was confirmed. To investigate the gas radiation effect on natural convection, trifluoromethane gas, which has significant radiative absorption, was used as a working fluid. By evaluating the interference fringe by the interferometer, the wave motion of the thermal boundary layer around the heated and adiabatic walls was visualized. Comparing the numerical calculation results (when varying the calculation conditions) revealed that the wave motion and turbulence boundary layer around the heated and adiabatic walls were caused by the gas radiation effect.
Original language English 1239-1249 11 International Journal of Heat and Mass Transfer 132 https://doi.org/10.1016/j.ijheatmasstransfer.2018.11.162 Published - 2019 Apr
## Keywords
• Gas radiation
• Interferometer
• LES
• Natural convection
• REM
• Surface radiation
• Turbulence
## ASJC Scopus subject areas
• Condensed Matter Physics
• Mechanical Engineering
• Fluid Flow and Transfer Processes
## Fingerprint
Dive into the research topics of 'Experimental evaluation of thermal radiation effects on natural convection with a Rayleigh number of 10<sup>8</sup>–10<sup>9</sup> by using an interferometer'. Together they form a unique fingerprint.
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.899243950843811, "perplexity": 2124.1976524799506}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "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-2021-31/segments/1627046154158.4/warc/CC-MAIN-20210801030158-20210801060158-00551.warc.gz"}
|
https://www.gamedev.net/topic/638041-max-players-with-unity-server/
|
• Create Account
## Max players with unity server
Old topic!
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.
17 replies to this topic
### #1Butabee Members
Posted 30 January 2013 - 02:23 AM
I heard Unity isn't very good for something like an MMO, but I guess that depends on just how a game is made. Right now I use the networkview components to synch player's transforms. Players out of a certain range of each other have their networkviews disabled. Using this method can anyone estimate how many players one server can support for a shooter with network updates happening at 12 a second plus sparse RPC calls? How big are the updates the network views send for transforms? I'd like to have one Mega server but I'm not sure it's possible. I may have to limit the enabled network views even if players are fairly close to each other. Although the way the game is designed, there isn't really a reason for mass gatherings besides maybe some players arranging big fights.
### #2ApochPiQ Moderators
Posted 30 January 2013 - 05:16 PM
You need to know three basic things:
• How big each update is in bytes (easy to capture with Wireshark or similar tools)
• How the number of updates scales with number of players - naive is O(n^2) which is impractical for large groups
• How much bandwidth you expect to budget - i.e. how many bytes/sec can each client handle, and more importantly, how many can the server handle
If you can assign metrics to that, basically all you have to do is solve this equation:
update_growth_function(num_players) * update_size_in_bytes = bandwidth_budget
Wielder of the Sacred Wands
### #3Butabee Members
Posted 30 January 2013 - 07:07 PM
Thanks, sounds good.
### #4Butabee Members
Posted 01 February 2013 - 01:05 AM
For anyone wondering... The typical networkview monitoring just the transform send 36 bytes per update. Found here: http://docs.unity3d.com/Documentation/Components/net-MinimizingBandwidth.html
### #5Kylotan Moderators
Posted 01 February 2013 - 07:36 AM
"In general, for most or all types of games - unless you're making major mistakes during design / development, up to around 20 players should be quite safe. [...] If you're very careful to make your game design "network-efficient", you can probably create an action-based multiplayer game based on Unity networking with a few more players. I think 50, maybe 100 should be doable unless everyone sees everyone all the time."
### #6Butabee Members
Posted 01 February 2013 - 04:16 PM
Hmmm, if only 36 bytes are sent per update, it seems like a fair amount more than 100 could be supported for an action game with a moderate update rate. I'm aiming for a 1MB/sec connection speed.
### #7SimonForsman Members
Posted 01 February 2013 - 05:26 PM
Butabee, on 01 Feb 2013 - 23:15, said:
Hmmm, if only 36 bytes are sent per update, it seems like a fair amount more than 100 could be supported for an action game with a moderate update rate. I'm aiming for a 1MB/sec connection speed.
The problem is the server, if you have 10 players and sync their 36 byte transforms 15 times per second the server has to send 9x10x36x15 bytes of data each second (thats 47.46 kbyte/s or 379kbps (37.9kbps per player)
with 20 players at the same updaterate you get 19x20x36x15 ~= 1600kbps (80kbps per player) (now its no longer possible to host the game on a DSL connection with 1Mbps upload, players can still play just fine with even a really weak 256kbps connection). at 50 players you get 49x50x36x15 ~= 10Mbps worth of bandwidth for the server (Still acceptable). at 100 players you'd hit ~40Mbps on the server at that update rate with just a single transform per player being synced. (Do you see where this is going ?) , 100 players in this scenario still only requires players to have a 400kbps connection (or one that never drops below that really) but the servers bandwidth requirements can start to making hosting difficult in some areas.
at 200 players the server bandwidth can hit 199x200x36x15 ~= 163Mbps, this is now pretty much impossible to host on a consumer connection (Allthough some regions have 1Gbps consumer connections now it is still fairly rare) and hosting costs for a commercial grade connection will be very high.
For an action game you probably want to update transforms atleast 15 times per second and you will have to send quite alot of other data aswell (a single transform per player isn't really enough for most games) so in order to keep the bandwidth usage on the server at a reasonable level you need to be a bit smart about it.
1) Keep the number of players in a given area low, the more players you got in a single area the more data your server has to send to each of them. (if you have 200 players on your server each playing in groups of 4 in their own little instance your server will only need to send 3x200x36x15 bytes/second instead of the 199x200x36x15 it would have to send if all 200 players were in the same area and able to see eachother)
2) Adapt the update rate based on distance or relevance. If playerA and playerB are far from eachother but still able to see eachother you can reduce the rate at which you send playerAs transforms to playerB and vice versa. (Not sure if unitys network views do this for you or not), if the game prevent rapid turning you could also avoid sending updates for things that lie too far outside the FoV
The exponential growth in bandwidth usage on the server is one of the harder problems to solve for large scale multiplayer games and it is the reason so many FPS games cap out at 64 players (Beyond that you will need a design that effectivly prevents large numbers of players from gathering in a single area or atleast discourages such gatherings so that they don't happen unless all players want it(and the inevitable lag that will follow) to happen), you might also have to write your own networking code rather than relying on Unitys network views (Unless they are more flexible than i've assumed)
Edited by SimonForsman, 01 February 2013 - 05:33 PM.
I don't suffer from insanity, I'm enjoying every minute of it.
The voices in my head may not be real, but they have some good ideas!
### #8Butabee Members
Posted 01 February 2013 - 06:26 PM
Oh, damn, for some reason I was thinking I'd only have to send players*update rate*update load from the server to players. Looks like I'll have to scale it back.
You can't adjust update rate on a networkview basis. Wish I could but nope. Unity's networking isn't real flexable.
I want to keep things as simple as possible and use the default networking. Kinda sucks but oh well.
Edited by Butabee, 01 February 2013 - 06:37 PM.
### #9SimonForsman Members
Posted 02 February 2013 - 06:55 AM
Butabee, on 02 Feb 2013 - 01:25, said:
Oh, damn, for some reason I was thinking I'd only have to send players*update rate*update load from the server to players. Looks like I'll have to scale it back.
You can't adjust update rate on a networkview basis. Wish I could but nope. Unity's networking isn't real flexable.
I want to keep things as simple as possible and use the default networking. Kinda sucks but oh well.
There are a few more scalable networking solutions available that you can use instead, Photon is pretty popular, very scalable and not that difficult to use. you can also use .Net sockets directly. (Sockets or custom networking modules are not available for iOS/Android unless you buy the pro version).
Edited by SimonForsman, 02 February 2013 - 07:00 AM.
I don't suffer from insanity, I'm enjoying every minute of it.
The voices in my head may not be real, but they have some good ideas!
### #10Butabee Members
Posted 02 February 2013 - 06:40 PM
For now I've managed to lower the update rate to 5 per second while simulating movement on both sides but the load also whent up by 12, although it's still a win. So that should allow a bit more players.
### #11Butabee Members
Posted 02 February 2013 - 09:58 PM
If anyone is having problems with network.instatiate leaving old copies of disconnected players around you have to make an RPC call with the RPCMode set to allbuffered that calls Network.RemoveRPCs Network.DestroyPlayerObjects. This only works if the objects were instatiated by a player.
This problem was driving me crazy for a whole day before I found a post about it buried in the web.
### #12Butabee Members
Posted 07 February 2013 - 11:12 PM
I've worked around the network views and pretty much do everything with RPCs. I also limited the amount of players that each player can receive updates for a second on the servier side.
With this I should be able to support 6000+ players assuming the server system can handle the physics. The networking could at least handle it... still not sure about the CPU and memory requirements.
### #13wodinoneeye Members
Posted 08 February 2013 - 08:18 AM
"Players out of a certain range of each other have their networkviews disabled."
Now if you can guarantee that N+1 players dont decide to all be in the same proxiimity (the old problem)
Shrinking areas (radius) that players can see ? -- If throttling update rates gets too infrequent too fast ....
----------------------------------
"6000+ players" unfortunately systems like this can bottleneck very quickly (at lower numbers than you expect) and sporadically (which even a fraction of the time can make the game unplayable)
Edited by wodinoneeye, 08 February 2013 - 08:21 AM.
--------------------------------------------Ratings are Opinion, not Fact
### #14ApochPiQ Moderators
Posted 08 February 2013 - 11:36 AM
Unity is going to barf with 6000 players in a single physics space.
Wielder of the Sacred Wands
### #15Butabee Members
Posted 08 February 2013 - 05:25 PM
I'm thinking I can turn off the colliders too and only send verty sparse player updates. Only smooth movement is based on the built in physics. I should be able to disable colliders for players outside viewing distance of others.
### #16ApochPiQ Moderators
Posted 08 February 2013 - 06:40 PM
I'm not deeply familiar with how well PhysX scales, but you're likely to run into a lot more problems than just separating your collider groups into simulation islands.
Wielder of the Sacred Wands
### #17Butabee Members
Posted 08 February 2013 - 06:56 PM
I tried turning off the colliders, and the player would crawl back to the old position at the time the collider was enabled when I tried moving.
I guess I'll see how low I can get the physics step without messing things up.
I'm also using character controllers for NPCs and players which aren't as strenuous as something like a rigidbody would be.
Edited by Butabee, 08 February 2013 - 07:23 PM.
### #18Butabee Members
Posted 08 February 2013 - 09:11 PM
I guess another thing I could do is disable static object colliders when nothing is near them.
Does Unity physics use any sort of space partitioning?
Old topic!
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.
|
{"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": 0.17092734575271606, "perplexity": 1695.073911368054}, "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-2017-04/segments/1484560280899.42/warc/CC-MAIN-20170116095120-00240-ip-10-171-10-70.ec2.internal.warc.gz"}
|
http://playzona.net/Illinois/good-standard-error-mean.html
|
Address 5048 W 81st Ave, Schererville, IN 46375 (219) 227-8015 http://www.integrous.biz
# good standard error mean Blue Island, Illinois
For data that are non-normal, the standard deviation can be a terrible estimator of scale. So, we should draw another sample and determine how much it deviates from the population mean. For smaller sample sizes, the use of n-1 is generally considered an appropriate correction, allowing the calculation of a sample standard deviation using N-1 as the denominator (Bessel's correction). Sometimes it is too difficult or costs too much money to have lots of samples.
And although I don't work with Power Law distributions, the Pareto distribution can reduce to a single parameter also, with no defined variance. This interval is a crude estimate of the confidence interval within which the population mean is likely to fall. Sep 29, 2014 Joshka Kaufmann · University of Lausanne I agree with Bernardo that distribution of your data is crucial. This often leads to confusion about their interchangeability.
On the other hand, if you assume Poisson distribution, then the mean should be approximately the square of the SD. The standard error of the mean does basically that. The margin of error and the confidence interval are based on a quantitative measure of uncertainty: the standard error. Just as the standard deviation is a measure of the dispersion of values in the sample, the standard error is a measure of the dispersion of values in the sampling distribution.
Next, consider all possible samples of 16 runners from the population of 9,732 runners. Notice, however, that once the sample size is reasonably large, further increases in the sample size have smaller effects on the size of the standard error of the mean. We could subtract the sample mean from the population mean to get an idea of how close the sample mean is to the population mean. (Technically, we don't know the value S is 3.53399, which tells us that the average distance of the data points from the fitted line is about 3.5% body fat.
In that case, the statistic provides no information about the location of the population parameter. The standard error of the mean permits the researcher to construct a confidence interval in which the population mean is likely to fall. Biochemia Medica 2008;18(1):7-13. The Cauchy distribution has, as Bernardo points out, no defined variance.
National Center for Health Statistics does not report an average if the relative standard error exceeds 30%. In fact, we might want to do this many, many times. Oct 1, 2014 Jochen Wilhelm · Justus-Liebig-Universität Gießen Thank you Ronán for your clarification. I'd say that the DS (and the variance) is in fact a statistical property of any distribution, but that it only has a meaning in the case of a normal distribution.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. Kind regards, Nicholas Name: Himanshu • Saturday, July 5, 2014 Hi Jim! The standard deviation of those means is then calculated. (Remember that the standard deviation is a measure of how much the data deviate from the mean on average.) The standard deviation I love the practical, intuitiveness of using the natural units of the response variable.
Sampling from a distribution with a large standard deviation The first data set consists of the ages of 9,732 women who completed the 2012 Cherry Blossom run, a 10-mile race held The standard error is a measure of the variability of the sampling distribution. As will be shown, the standard error is the standard deviation of the sampling distribution. M.
What the standard error gives in particular is an indication of the likely accuracy of the sample mean as compared with the population mean. Therefore, the standard error of the estimate is a measure of the dispersion (or variability) in the predicted scores in a regression. Ricky Ramadhian · Lampung University when data , CV >=1, it should be repeated the experiment or how? Conveniently, it tells you how wrong the regression model is on average using the units of the response variable.
The concept of a sampling distribution is key to understanding the standard error. Because of random variation in sampling, the proportion or mean calculated using the sample will usually differ from the true proportion or mean in the entire population. Set the sample size to a small number (e.g. 1) and generate the samples. Each of these averages is a little bit different from the average that would come from measuring every 42cm long redfish (which is not possible anyway).
For example, you have a mean delivery time of 3.80 days with a standard deviation of 1.43 days based on a random sample of 312 delivery times. See unbiased estimation of standard deviation for further discussion. The mean age for the 16 runners in this particular sample is 37.25. Ramadhian:Is this question in regards to the reliability of your data, or is it more about effect sizes (or something else)?
They are quite similar, but are used differently. And that means that the statistic has little accuracy because it is not a good estimate of the population parameter. Standard errors provide simple measures of uncertainty in a value and are often used because: If the standard error of several individual quantities is known then the standard error of some If you have several treatments or different samplings you would like to compare, the overall distribution of your variable might be spread out for example.
Oct 9, 2014 Debashis Chakraborty · Indian Agricultural Research Institute I apreciate Sorensen's comments. The following expressions can be used to calculate the upper and lower 95% confidence limits, where x ¯ {\displaystyle {\bar {x}}} is equal to the sample mean, S E {\displaystyle SE} Another way to find the standard error of the mean is to use an equation that needs only one sample. Taken together with such measures as effect size, p-value and sample size, the effect size can be a very useful tool to the researcher who seeks to understand the reliability and
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.9453752040863037, "perplexity": 419.92753132860054}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.3, "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-2018-43/segments/1539583509845.17/warc/CC-MAIN-20181015205152-20181015230652-00062.warc.gz"}
|
http://www.cs.nyu.edu/web/Academic/Graduate/specsp08.html
|
Graduate Special Topics in Computer Science
NOTE: for descriptions of standard graduate computer science courses, see Graduate Course Descriptions.
#### G22.3033-001 Computational Systems Biology
Presently, there is no clear way to determine if the current body of biological facts is sufficient to explain phenomenology. In the biological community, it is not uncommon to assume certain biological problems to have achieved a cognitive finality without rigorous justification. In these particular cases, rigorous mathematical models with automated tools for reasoning, simulation, and computation can be of enormous help to uncover cognitive flaws, qualitative simplification or overly generalized assumptions. Some ideal candidates for such study would include: prion hypothesis, cell cycle machinery (DNA replication and repair, chromosome segregation, cell-cycle period control, spindle pole duplication, etc.), muscle contractility, processes involved in cancer (cell cycle regulation, angiogenesis, DNA repair, apoptosis, cellular senescence, tissue space modeling enzymes, etc.), signal transduction pathways, circadian rhythms (especially the effect of small molecular concentration on its robustness), and many others. We believe that the difficulty of biological modeling will become acute as biologists prepare to understand even more complex systems.
The goal of this course is to understand, design and create a large-scale computational system centered on the biology of individual cells, population of cells, intra-cellular processes, and realistic simulation and visualization of these processes at multiple spatio-temporal scales. Such a reasoning system, in the hands of a working biologist, can then be used to gain insight into the underlying biology, design refutable biological experiments, and ultimately, discover intervention schemes to suitably modify the biological processes for therapeutic purposes.
(1) Evolutionary Biology (2) Computability in Biology (3) Reconstructibility in Biology (4) Biology of Cancer (5) Biology of Aging
#### G22.3033-002 Applied Math for Algorithms
Although many mathematics courses have content that is useful in the design and analysis of algorithms, the more applicable material often comprises no more than 10% of the curriculum.
This course will endeavor to present that critical 10% as culled from a handful of math courses and other sources. We will also endeavor to show how this material is applied in the design or analysis of algorithms.
Some of the subjects that will be covered are:
Performance-related equations and their direct solution.
Recurrence equations: first order difference equations and beyond. Eigenfunction methods, multiplicity of eigenvalues, etc.
ODEs and their use in performance analyses. A limited presentation of limit theorems.
PDEs and their use in performance analyses. Limited implications of limit theorems.
Probability, and what properly educated theoreticians might wish to know. Conditional expectations are a powerful highly expressive tool with a foundation that is based on measure theory yet the concept allows us to present proofs and to acquire understandings about probabilistic processes that would otherwise be difficult to formalize. It is also worth understanding what the central limit theorem says, what it means, what it implies, and what it does not imply. Likewise, it is useful to understand the more basic probability distributions and the physical processes that they model.
Statistics is a little different from probability. One of the areas of statistical analysis that has had significant impact in TCS is the theory of Hoeffding-Chernoff bounds. It is probably a good idea to know how this material applies to more than Bernoulli Trials, and to stopping times in particular. We might also cover some issues in the computation of random variables, and at least comment on the importance of extreme points in the space of probability distributions (which is to say that we will survey majorization results).
Complex variables give valuable insights about the solution to many algorithms-based difference equations, and provide the theory necessary for computing saddle point estimates and understanding some of the limit results for PDEs.
Combinatorics is less systematic than analysis, but gives a rich set of techniques that are as varied as tableau methods (used to count seemingly complicated outcomes) and the probabilistic method (which is arguably more combinatorial that probabilistic).
Additional topics will be included as time/opportunities permit.
#### G22.3033-003 Data Mining
We live in the Age of Information. The importance of collecting data that reflects a business or scientific activity to achieve competitive advantage is widely recognized now. Advanced systems for collecting data and managing it in large databases are in place in most large and mid-range companies. However, the bottleneck of turning this data into your success is the difficulty of extracting knowledge about the system from the collected data.
What goods should be promoted to this customer? What is the probability that a certain customer will respond to a planned promotion? Can one predict the most profitable securities to buy/sell during the next trading session? Will this customer default on a loan or pay back on schedule? What medical diagnosis should be assigned to this patient? How large are the peak loads of a telephone or energy network going to be? Why does the manufacturing facility suddenly start to produce defective goods?
These are all the questions that can be answered if information hidden in a database can be found explicitly and utilized. Modeling the investigated system and discovering relations that connect variables are the subject of data mining.
The course will introduce concepts and techniques of data mining and data warehousing, including concept, principle, architecture, design, implementation, application of data warehousing and data mining. TOPICS: Data warehousing and OLAP technology for data mining Data preprocessing Descriptive data mining: characterization and comparison Association analysis Classification and prediction Cluster analysis Mining complex types of data Applications and trends in data mining
#### G22.3033-004 Web Development with Ruby on Rails
This course begins with an in-depth examination of the Ruby language and moves on to web development within the Ruby on Rails framework. An emphasis is placed on understanding the particular features of the Ruby language, how the language compares to others like Java and Python, and how it facilitates the creation of frameworks such as Ruby on Rails. This course is recommended for students with a strong interest in programming languages, web development frameworks, and software engineering. No experience with Ruby or Ruby on Rails is assumed.
#### G22.3033-005 Game Theory, Learning & Planning
There have been many instances in the recent literature in which algorithmic thinking is combined with game-theoretic, or, more specifically, socio-economic concepts to address problems arising in diverse contexts. The purpose of this course is to seize this moment and promote this interaction to create a field of Social Operating Systems (SOS).'' The emphasis will be on mathematically sophisticated techniques in the interface between algorithms, learning, optimization and game theory, as well as their applications to planning. Our primary motivation comes from our work on PLAN C (Planning with Large Agent network against Catastrophes; http://www.bioinformatics.nyu.edu/Projects/planc/index.shtml), which provides emergency management and response plans in face of man-made or natural disasters.
Topics will include some of the following (the list will crystallize gradually after initial discussions in the first class): 1: Game Theory, Nash equilibrium and General Equilibrium 2: Evolutionary game theory and Repeated Games 3: Bounded rationality: Example of Santa Fe Bar Problems 4: Social choice theory: Condorcet, Sen & Arrow 5: Elections, Technorati-Tags and Internet 6: Mechanism design 7: Multiple Objective Functions and Pareto Optimality 8: Multi-Objective Optimization Problems (MOOP) 9: Social Software: Planning (Catastrophe Response) 10: Modeling Social Networks & Bounded Rationality 11: Using Social Networks to Survey, Sample and Search 12: Collaborative Filtering: Recommender Design 13: Collaborative Filtering: Search Engines 14: Collaborative Filtering: Population Sampling and Surveys
#### G22.3033-006 Computational Photography
Course description: Computational Photography is an exciting new area at the intersection of Computer Graphics and Computer Vision. Through the use of computation, its goal is to move beyond the limitations of conventional photography to produce enhanced and novel imagery of the world around us. The main focus of the course will be on software-based methods for producing visually compelling pictures. However, it will also cover novel camera designs, for which computation is integral to their operation. The course will explain the principles behind many of the advanced tools that can be found in Adobe Photoshop, although the use of this package itself is outside the scope of the course. The course will be suitable for advanced undergraduates, masters and PhD students. A reasonable knowledge of linear algebra is required and familiarity with Matlab is desirable. Assessment will be through coursework and a course project.
#### G22.3033-007 Probabilistically Checkable Proofs and Hardness of Approximation
Many optimization problems of theoretical and practical interest are NP-complete, meaning it is impossible to compute exact solutions to these problems in polynomial time unless P = NP. A natural way to cope with this curse of NP-completeness is to seek approximate solutions instead of exact solutions. An algorithm with approximation ratio C computes, for every problem instance, a solution whose cost is within a factor C of the optimum. Optimization problems exhibit a wide range of behavior in their approximability. It is well-known that Bin-Packing has an approximation algorithm with ratio 1+\epsilon for every \epsilon > 0. In theory jargon, we say that Bin-Packing has a polynomial-time approximation scheme (PTAS). However, it wasn't known till the early 90s whether problems like MAX-3SAT, Vertex Cover, and MAX-CUT have a PTAS. A celebrated result called the PCP Theorem finally showed that these problems have no PTAS unless P = NP. Such results that rule out the possibility of good approximation algorithms (under complexity theoretic assumptions like P != NP) are called inapproximability results or hardness of approximation results.
The PCP Theorem has an equivalent formulation from the point of view of proof checking. The PCP theorem states that every NP-statement has a probabilistically checkable proof, i.e. a proof which can be "spot-checked" by reading only a constant number of bits from the proof. These bits are selected by a randomized process using a very limited amount of randomness. The checking process always accepts a correct proof of a correct statement and rejects any cheating proof of an incorrect statement with high probability. The term "holographic proof" is sometimes used to highlight this feature that a cheating proof must be wrong everywhere and therefore, can be detected by a spot-check. The discovery of the connection between proof checking and inapproximability results is one of the most exciting theoretical developments in the last decade. Since then, PCPs have led to several breakthrough results in inapproximability theory, e.g. tight hardness results for Clique, MAX-3SAT, and Set Cover.
This course will cover many of the inapproximability results and PCPs used to prove them. No prior knowledge will be assumed, except the basic theory of NP-completeness. Participants are expected to scribe notes for one lecture and/or give one presentation. No assignments/exams!
|
{"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": 0.43766558170318604, "perplexity": 1251.4200497781196}, "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-2014-23/segments/1406510272940.33/warc/CC-MAIN-20140728011752-00055-ip-10-146-231-18.ec2.internal.warc.gz"}
|
https://experts.illinois.edu/en/publications/low-head-hydropower-as-a-reserve-power-source-a-case-study-of-nor
|
# Low-head hydropower as a reserve power source: A case study of Northeastern Illinois
Trevor L. Auth, Grace E. Wackerman, Marcelo H. Garcia, Ashlynn S. Stillwell
Research output: Contribution to journalArticlepeer-review
## Abstract
Wind power generation faces intermittency challenges, typically requiring reserve power sources to maintain reliability of the electricity grid. This study proposes that hydropower turbines installed at low-head dams can provide reserve power generation to support wind power, avoiding the externalities associated with fossil-fuel plants and conventional hydropower. Low-head dams in the United States are used for flood control, securing municipal water supplies, and providing reservoir pools for recreation. As a case study, we estimated hydropower potential at 12 low-head dams along a 150-km reach of the Fox River (Northeastern Illinois, USA) using a calibrated river flow model. We analyzed the model's output to assess power generation capacity and reliability as a source of baseload power and as a component in a coupled wind-hydropower system. The modeled system performed reliably over a five-year time period despite significant long-term fluctuations in streamflow, offsetting the short-term variability of wind power. However, combining the low-head hydropower system with wind power limited the output of the system to the minimum generated by the low-head hydropower. The low-head hydropower system's small capacity and high break-even price suggest that it is better suited for local applications rather than grid-scale operations, especially if permitting regulations are considered.
Original language English (US) 980-989 10 Renewable Energy 175 https://doi.org/10.1016/j.renene.2021.04.099 Published - Sep 2021
## Keywords
• Energy system analysis
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.8419838547706604, "perplexity": 10011.720328444238}, "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-2022-40/segments/1664030335504.37/warc/CC-MAIN-20220930212504-20221001002504-00401.warc.gz"}
|
http://en.wikipedia.org/wiki/Simplification
|
# Simplification
For simplification of fractions, see Equivalent fractions. For other uses, see Simplification (disambiguation).
In propositional logic, simplification[1][2][3] (equivalent to conjunction elimination and also called and elimination) is a valid immediate inference, argument form and rule of inference which makes the inference that, if the conjunction A and B is true, then A is true, and B is true. The rule makes it possible to shorten longer proofs by deriving one of the conjuncts of a conjunction on a line by itself.
An example in English:
It's raining and it's pouring.
Therefore it's raining.
The rule can be expressed in formal language as:
$\frac{P \land Q}{\therefore P}$
or as
$\frac{P \land Q}{\therefore Q}$
where the rule is that whenever instances of "$P \land Q$" appear on lines of a proof, either "$P$" or "$Q$" can be placed on a subsequent line by itself.
## Formal notation
The simplification rule may be written in sequent notation:
$(P \land Q) \vdash P$
or as
$(P \land Q) \vdash Q$
where $\vdash$ is a metalogical symbol meaning that $P$ is a syntactic consequence of $P \land Q$ and $Q$ is also a syntactic consequence of $P \land Q$ in logical system;
and expressed as a truth-functional tautology or theorem of propositional logic:
$(P \land Q) \to P$
and
$(P \land Q) \to Q$
where $P$ and $Q$ are propositions expressed in some formal system.
## References
1. ^ Copi and Cohen[citation needed]
2. ^ Moore and Parker[citation needed]
3. ^ Hurley[citation needed]
|
{"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": 0, "img_math": 16, "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": 0.9449661374092102, "perplexity": 357.0603742438485}, "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-2015-11/segments/1424936461332.16/warc/CC-MAIN-20150226074101-00082-ip-10-28-5-156.ec2.internal.warc.gz"}
|
http://mathhelpforum.com/algebra/125971-how-can-i-find-limits-function-equation.html
|
# Thread: How can i find the limits of this function/equation?
1. ## How can i find the limits of this function/equation?
Hello!
I have no idea where to post this so I'll just put it here.
The function f(x)= 1 - [2x/(1+(x^2))]
Sorry if this is confusing, ive written it all out on paint so please open the attached file
QUESTION:
to display the graph of y=f(x) for -10<x<10, a suitable interval for y, a<x<b must be chosen. Suggest appropriate values for a and b.
I would suppose that you substitute x=-10 and x=10 to find a and b accordingly yet I cant get the right answer
Thank you!
2. For one, you just look at it. Imagine what it does at its extremes.
If x increases without bound, getting larger and larger...
a) What does '1' do? Nothing.
b) What does the rational expression do? It shrinks. This piece disappears.
c) So, we seem to be sneaking up on x = 1 from the bottom.
If x decreases without bound, getting larger and larger in the negative direction...
a) What does '1' do? Nothing.
b) What does the rational expression do? It shrinks. This piece disappears.
c) So, we seem to be sneaking up on x = 1 from the top.
We just defined an horizontal asymptote. x = 1.
What do you suppose is next?
|
{"extraction_info": {"found_math": false, "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": 0, "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": 0.923706591129303, "perplexity": 1121.6268828482746}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "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-2017-39/segments/1505818685850.32/warc/CC-MAIN-20170919145852-20170919165852-00569.warc.gz"}
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.