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title: Simulation of electromagnetically and magnetically induced transparency in a magnetized plasma; abstract: Electromagnetically induced transparency (EIT), a phenomenon well known in atomic systems, has a natural analogy in a classical magnetized plasma. The magnetized plasma has a resonance for right-hand polarized electromagnetic waves at the electron cyclotron frequency Ω0, so that a probe wave with frequency ω1=Ω0 cannot propagate through the plasma. The plasma can be made transparent to such a probe by the presence of a pump wave. The pump may be an electromagnetic wave or magnetostatic wiggler. Simulations and theory show that the physical reason for the transparency is that the beating of the probe wave with the pump wave sets up a plasma oscillation, and the upper sideband of the pump wave cancels the resonant plasma current due to the probe. The theory of plasma EIT derived here extends that found in the earlier work to include the effects of the lower sideband of the pump and renormalization of the plasma frequency and an analysis of the transient response. A detailed comparison of theory to one-dimen... | 162,000 |
title: Angular analysis of B0→φK* decays and search for CP violation at Belle; abstract: We report the measurements of branching fractions and CP violation asymmetries in $B^0 \\to \\phi K^{*}$ decays obtained in an angular analysis using the full data sample of $772 \\times 10^6 B\\bar{B}$ pairs collected at the $\\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We perform a partial wave analysis to distinguish among scalar [$B^0 \\to vector [$B^0 \\to \\phi K^{*}(892)^{0}$] and tensor [$B^0 \\to \\phi K^{*}_{2}(1430)^{0}$] components, and determine the corresponding branching fractions to be $\\mathcal{B}[B^0 \\to \\phi(K\\pi)^{*}_{0}] = (4.3 \\pm 0.4 \\pm 0.4) \\times 10^{-6}$, $\\mathcal{B}[B^0 \\to \\phi K^{*}(892)^{0}] = (10.4 \\pm 0.5 \\pm 0.6) \\times 10^{-6}$ and $\\mathcal{B}[B^0 \\to \\phi K^{*}_{2}(1430)^{0}] = (5.5 ^{+0.9}_{-0.7} \\pm 1.0) \\times 10^{-6}$. We also measure the longitudinal polarization fraction $f_L$ in $B^0 \\to \\phi K^{*}(892)^{0}$ and $B^0 \\to \\phi K^{*}_{2}(1430)^{0}$ decays to be $0.499 \\pm 0.030 \\pm 0.018$ and $0.918 ^{+0.029}_{-0.060} \\pm 0.012$, respectively. The first quoted uncertainties are statistical and the second are systematic. In total, we measure 26 parameters related to branching fractions, polarization and CP violation in the $B^0 \\to \\phi K^{*}$ system. No evidence for CP violation is found. | 162,001 |
title: Discovery of pulsation dropout and turn-on during the high state of the accreting X-ray pulsar LMC X-4; abstract: Two \\textit{NuSTAR} observations of the luminous X-ray pulsar LMC X-4 in October and November 2015 captured several bright accretion flares from this source, which has a long history of stable pulse and superorbital behavior. We present a timing analysis of these data in which we detect a rapid pulse turn-on in association with the accretion flares, during which the source reaches super-Eddington luminosities. Pulsations, which are normally seen from this source, are found to only occur for approximately one hour before and during the bright flares. Beyond one hour before and after the flares, we find pulsations to be weak or nonexistent, with fractional RMS amplitudes of less than 0.05. At the onset of the flare, the pulse profiles exhibit a phase shift of 0.25 cycles that could be associated with a change in the emission geometry. This increase in pulse strength occurring well before the flare cannot be explained by the propeller effect, and potentially offers a connection between the magnetic properties of pulsars that accrete close to their Eddington limits and ULX pulsars. | 162,002 |
title: Experiments on thermal convection in rotating systems motivated by planetary problems; abstract: Abstract Thermal convection in deep planetary atmospheres or in planetary and stellar interiors is characterized by a finite angle between the vectors of rotation and gravity. This situation can be modelled in laboratory experiments through the use of centrifugal buoyancy. Earlier observations and recent measurements are reviewed and some new results are reported. Attention will be focused on experiments with a rotating cylindrical annulus and with rotating half-spheres. In some respects measurements and predictions of linear theory are in reasonable agreement; in other respects discrepancies exist. The observed transitions to a subharmonic frequency and to an aperiodic time dependence have not yet been understood on the basis of available non-linear theoretical models. | 162,003 |
title: Comparison of Tomo-PIV and 3D-PTV for microfluidic flows; abstract: Two 3D-3C velocimetry techniques for micro-scale measurements are compared: tomographic particle image velocimetry (Tomo-PIV) and 3D particle-tracking velocimetry (3D-PTV). Both methods are applied to experimental data from a confined shear-driven liquid droplet over a moving surface. The droplet has 200 ?m height and 2?mm diameter. Micro 3D-PTV and Tomo-PIV are used to obtain the tracer particle distribution and the flow velocity field for the same set of images. It is shown that the reconstructed particle distributions are distinctly different, where Tomo-PIV returns a nearly uniform distribution over the height of the volume, as expected, and PTV reveals a clear peak in the particle distribution near the plane of focus. In Tomo-PIV, however, the reconstructed particle peak intensity decreases in proportion to the distance from the plane of focus. Due to the differences in particle distributions, the measured flow velocities are also different. In particular, we observe Tomo-PIV to be in closer agreement with mass conservation. Furthermore, the random noise level is found to increase with distance to the plane of focus at a higher rate for 3D-PTV as compared to Tomo-PIV. Thus, for a given noise threshold value, the latter method can measure reliably over a thicker volume. | 162,004 |
title: Gradient flows without blow-up for Lefschetz thimbles; abstract: We propose new gradient flows that define Lefschetz thimbles and do not blow up in a finite flow time. We study analytic properties of these gradient flows, and confirm them by numerical tests in simple examples. | 162,005 |
title: Discriminating between Z'-boson effects and effects of anomalous gauge couplings in the double production of W ± bosons at a linear collider; abstract: The potential of the International Linear electron-positron Collider (ILC) for seeking, in the annihilation production of W ±-boson pairs, signals induced by new neutral gauge bosons predicted by models belonging to various classes and featuring an extended gauge sector is studied. Limits that will be obtained at ILC for the parameters and masses of Z′ bosons are compared with present-day and future data from the Large Hadron Collider (LHC). The possibility of discriminating between the effects of Z-Z′ mixing and signals induced by anomalous gauge couplings (AGC) is demonstrated within theoretically motivated trilinear gauge models involving several free anomalous parameters. It is found that the sensitivity of ILC to the effects of Z-Z′ mixing in the process e + e − → W + W − and its ability to discriminate between these two new-physics scenarios, Z′ and AGC, become substantially higher upon employing polarized initial (e + e −) and final (W ±) states. | 162,006 |
title: Combined Search for the Standard Model Higgs Boson Decaying to bb̄ Using the D0 Run II Data Set; abstract: We present the results of the combination of searches for the standard model Higgs boson produced in association with a W or Z boson and decaying into b bbar using the data sample collected with the D0 detector in p pbar collisions at sqrt{s}=1.96 TeV at the Fermilab Tevatron Collider. We derive 95% CL upper limits on the Higgs boson cross section relative to the standard model prediction in the mass range 100 GeV \u003c= M_H \u003c= 150 GeV, and we exclude Higgs bosons with masses smaller than 102 GeV at the 95% CL. In the mass range 120 GeV \u003c= M_H \u003c= 145 GeV the data exhibit an excess above the background prediction with a global significance of 1.5 standard deviations, consistent with the expectation in the presence of a standard model Higgs boson. | 162,007 |
title: Pyroelectric response of lead zirconate titanate thin films on silicon: Effect of thermal stresses; abstract: Ferroelectric lead zirconate titanate [Pb(ZrxTi1-xO)3, (PZT x:1-x)] has received considerable interest for applications related to uncooled infrared devices due to its large pyroelectric figures of merit near room temperature, and the fact that such devices are inherently ac coupled, allowing for simplified image post processing. For ferroelectric films made by industry-standard deposition techniques, stresses develop in the PZT layer upon cooling from the processing/growth temperature due to thermal mismatch between the film and the substrate. In this study, we use a non-linear thermodynamic model to investigate the pyroelectric properties of polycrystalline PZT thin films for five different compositions (PZT 40:60, PZT 30:70, PZT 20:80, PZT 10:90, PZT 0:100) on silicon as a function of processing temperature (25–800 °C). It is shown that the in-plane thermal stresses in PZT thin films alter the out-of-plane polarization and the ferroelectric phase transformation temperature, with profound effect on the ... | 162,008 |
title: Isoscalar and isovector giant resonances in 92,94,96,98,100Mo and 90,92,94Zr; abstract: Abstract The response functions, S(E), and centroid energies, ECEN, of the isoscalar and isovector giant resonances of multipolarity L = 0–3 in 92,94,96,98,100Mo and 90,92,94Zr have been calculated employing the spherical Hartree-Fock (HF) based random phase approximation (RPA) method, using the Skyrme-type effective nucleon-nucleon interaction. In particular, we investigate the recent experimental results of the uncharacteristic behavior of ECEN for the isoscalar giant resonances, by extending our HF-based RPA calculations with only the KDE0v1 interaction to 32 additional Skyrme interactions. The main result of our investigation is that we find significant disagreements between the theoretical and the experimental values of ECEN for isoscalar giant monopole and dipole resonance of some nuclei. For the isoscalar giant octupole resonance we find the theoretical values of the ECEN to be well above the experimental results. We also study the sensitivity of ECEN to nuclear matter (NM) properties, including the effective mass, the incompressibility coefficient and the symmetry energy at saturation density, by determining the Pearson linear correlation coefficient between the calculated values of ECEN and the various nuclear matter properties of each Skyrme parametrization. For the isovector giant dipole resonance we find good agreement between the experimental and theoretical values of ECEN for Skyrme interactions with values of the enhancement coefficient of the energy weighted sum rule, κ, in the range between 0.25–0.70. | 162,009 |
title: Asymptotic analyses of the start-up stage of Couette flow subjected to different boundary conditions; abstract: Abstract In this article, the process for reaching “developed” stage was investigated under both imposed shear stress and specified velocity boundary conditions. Four specific situations are investigated. These are (1) constant shear stress, (2) linearly increasing shear stress from zero shear, (3) constant velocity and (4) linearly increasing velocity from stationary. Analytical solutions of velocity distributions under these four situations were obtained. A dimensionless viscosity, defined as the ratio of the measured viscosity calculated based on the measuring principle of Couette-type viscometer to the true viscosity of fluid was proposed to describe the initial transient period. We define the “developed” stage when the dimensionless viscosity is 1% away from its final value or when it reaches 1.01. By analyzing Stokes\u0027 first problem, compact models of the dimensionless viscosity were expressed and exact quantitative relations among the initial values of dimensionless viscosity under these four specific situations were found. Time periods for Couette flow to reach the “developed” stage was calculated. The development time is the shortest under the constant velocity boundary and is the longest under the linearly increasing shear stress boundary. | 162,010 |
title: Quasi-elastic scattering of 153 MeV protons by p-state protons in C12: I. Experimental; abstract: Abstract For the reaction C 12 (p, 2p)B 11 at 153 MeV, the energies of the two protons enitted in each event are measured with plastic scintillators, and added. The summed-energy spectrum shows a well-defined peak corresponding to an energy loss of 16 MeV in the reaction, and events in this peak are interpreted as those in which a proton is knocked out of the p-shell in carbon. For coplanar p-state events, angular correlations and energy spectra are measured with one counter fixed at 15°, 20°, 30°, 40°, 60° and 80° relative to the incident beam and the angle of the other varied between 15° and 80° on the other side of the beam. The angular correlations are sharply peaked, while for the peak the separation angle between the two outgoing protons depends markedly on the angle at which one proton is detected, varying from 35° when the fixed counter is set at 15° to 110° when it is at 80°. The results are consistent with the mechanism of quasi-elastic p-p scattering when the momentum distribution of the struck protons is taken into account. A rough value is obtained for the total cross-section for p-state events. It is about one-sixth of the expected value in the absence of absorption, thus showing the importance of this process. By comparison of the experimental results with distorted-wave calculations it should be possible to determine the momentum distribution of the p-state protons and the magnitude of the distortion effects themselves. | 162,011 |
title: Large nonlinear refraction in pulsed laser deposited BCZT thin films on quartz substrates; abstract: Optical thin films based on ferroelectric materials are forerunners for novel optoelectronic and photonic applications due to their large inherent coupling between optical and electrical properties. We report here on the thickness dependence of linear and nonlinear optical properties of polycrystalline Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) thin films fabricated on quartz substrates by the pulsed laser deposition technique. In order to probe the linear optical properties of BCZT thin films, we have obtained optical transmission spectra from which the optical parameters like the refractive index and extinction coefficient were deduced using the Swanepoel method. Using the Sellemier relation, we have estimated the oscillator parameters like oscillator strength and oscillator energy from the refractive index dispersion data, which are indicative of the efficiency of the electro-optic coupling process. Further, the third-order optical nonlinearity of these thin films was measured by a closed-aperture Z-scan technique with a low-power, continuous-wave He-Ne laser as the excitation source. These films exhibited high optical nonlinearity, and the nonlinear refractive index was determined to be similar to 5 x 10(-7) m(2)/W. The enhanced nonlinear refraction in BCZT thin films at the low power regime could be attributed to both photothermal and photorefractive origin with a plausible larger contribution from the latter. Such a large nonlinear optical response exhibited at low optical powers in BCZT thin films is very promising technologically, as it may find applications in a number of photonic devices such as optical interconnects, optical processors, optical memories, and waveguide modulators. (C) 2018 Optical Society of America. | 162,012 |
title: The Orion fingers: H$_2$ temperatures and excitation in an explosive outflow; abstract: We measure H$_2$ temperatures and column densities across the Orion BN/KL explosive outflow from a set of thirteen near-IR H$_2$ rovibrational emission lines observed with the TripleSpec spectrograph on Apache Point Observatory\u0027s 3.5-meter telescope. We find that most of the region is well-characterized by a single temperature (~2000-2500 K), which may be influenced by the limited range of upper energy levels (6000-20,000 K) probed by our data set. The H$_2$ column density maps indicate that warm H$_2$ comprises 10$^{-5}$ - 10$^{-3}$ of the total H$_2$ column density near the center of the outflow. Combining column density measurements for co-spatial H$_2$ and CO at T = 2500 K, we measure a CO/H$_2$ fractional abundance of 2$\\times$10$^{-3}$, and discuss possible reasons why this value is in excess of the canonical 10$^{-4}$ value, including dust attenuation, incorrect assumptions on co-spatiality of the H$_2$ and CO emission, and chemical processing in an extreme environment. We model the radiative transfer of H$_2$ in this region with UV pumping models to look for signatures of H$_2$ fluorescence from H I Ly$\\alpha$ pumping. Dissociative (J-type) shocks and nebular emission from the foreground Orion H II region are considered as possible Ly$\\alpha$ sources. From our radiative transfer models, we predict that signatures of Ly$\\alpha$ pumping should be detectable in near-IR line ratios given a sufficiently strong source, but such a source is not present in the BN/KL outflow. The data are consistent with shocks as the H$_2$ heating source. | 162,013 |
title: Effects of polymer additives in the bulk of turbulent thermal convection; abstract: We present experimental evidence that a minute amount of polymer additives can significantly enhance heat transport in the bulk region of turbulent thermal convection. The effects of polymer additives are found to be the enhancement of coherent heat fluxes and suppression of incoherent heat fluxes. The enhanced heat transport is associated with the increased coherency of thermal plumes, as a result of the suppression of small-scale turbulent fluctuations by polymers. The incoherent heat flux, arising from turbulent background fluctuations, makes no net contribution to heat transport. The fact that polymer additives can increase the coherency of thermal plumes is supported by the measurements of a number of local quantities, such as the extracted plume amplitude and width, the velocity autocorrelation functions and the velocity temperature cross-correlation coefficient. The results from local measurements also suggest the existence of a threshold value for the polymer concentration, only above which significant modification of the plume coherent properties and enhancement of the local heat flux can be observed. Estimation of the plume emission rate suggests a stabilization of the thermal boundary layer by polymer additives. | 162,014 |
title: EOSDB: The Database for Nuclear EoS; abstract: Nuclear equation of state (EoS) plays an important role in understanding the formation of compact objects such as neutron stars and black holes. The true nature of the EoS has been a matter of debate at any density range not only in the nuclear physics but also in the astronomy and astrophysics. We have constructed a database of EoSs by compiling data from the literature. Our database contains the basic properties of the nuclear EoS of symmetric nuclear matter and of pure neutron matter. It also includes the detailed information about the theoretical models, for example the adopted methods and assumptions in individual models. The novelty of the database is to consider new experimental probes such as the symmetry energy, its slope relative to the baryon density, and the incompressibility, which enables the users to check their model dependences. We demonstrate the performance of the EOSDB through the examinations of the model dependence among different nuclear EoSs. It is reveled that some theoretical EoSs, which is commonly used in astrophysics, do not satisfactorily agree with the experimental constraints. | 162,015 |
title: Production of $$\mathbf {\Sigma (1385)^{\pm }}$$ Σ ( 1385 ) ± and $$\mathbf {\Xi (1530)^{0}}$$ Ξ ( 1530 ) 0 in proton–proton collisions at $$\mathbf {\sqrt{s}=}$$ s = 7 TeV; abstract: The production of the strange and double-strange baryon resonances (\n $$\\Sigma (1385)^{\\pm }$$\n , $$\\Xi (1530)^{0}$$\n ) has been measured at mid-rapidity (\n $$\\left| y \\right| $$\n $$\u003c0.5$$\n ) in proton–proton collisions at $$\\sqrt{s}$$\n $$=$$\n 7 TeV with the ALICE detector at the LHC. Transverse momentum spectra for inelastic collisions are compared to QCD-inspired models, which in general underpredict the data. A search for the $$\\phi (1860)$$\n pentaquark, decaying in the $$\\Xi \\pi $$\n channel, has been carried out but no evidence is seen. | 162,016 |
title: Alignment of the CMS Silicon Strip Tracker during stand-alone Commissioning; abstract: The results of the CMS tracker alignment analysis are presented using the data from cosmic tracks, optical survey information, and the laser alignment system at the Tracker Integration Facility at CERN. During several months of operation in the spring and summer of 2007, about five million cosmic track events were collected with a partially active CMS Tracker. This allowed us to perform first alignment of the active silicon modules with the cosmic tracks using three different statistical approaches; validate the survey and laser alignment system performance; and test the stability of Tracker structures under various stresses and temperatures ranging from +15C to -15C. Comparison with simulation shows that the achieved alignment precision in the barrel part of the tracker leads to residual distributions similar to those obtained with a random misalignment of 50 (80) microns in the outer (inner) part of the barrel. Comment: 41 pages, 63 postscript figures, submitted to JINST | 162,017 |
title: Dark matter searches using gravitational wave bar detectors: Quark nuggets and newtorites; abstract: Abstract Many experiments have searched for supersymmetric WIMP dark matter, with null results. This may suggest to look for more exotic possibilities, for example compact ultra-dense quark nuggets, widely discussed in literature with several different names. Nuclearites are an example of candidate compact objects with atomic size cross section. After a short discussion on nuclearites, the result of a nuclearite search with the gravitational wave bar detectors Nautilus and Explorer is reported. The geometrical acceptance of the bar detectors is 19.5 m 2 sr, that is smaller than that of other detectors used for similar searches. However, the detection mechanism is completely different and is more straightforward than in other detectors. The experimental limits we obtain are of interest because, for nuclearites of mass less than 10 − 5 g, we find a flux smaller than that one predicted considering nuclearites as dark matter candidates. Particles with gravitational only interactions (newtorites) are another example. In this case the sensitivity is quite poor and a short discussion is reported on possible improvements. | 162,018 |
title: Effective Description of Higher-Order Scalar-Tensor Theories; abstract: Most existing theories of dark energy and/or modified gravity, involving a scalar degree of freedom, can be conveniently described within the framework of the Effective Theory of Dark Energy, based on the unitary gauge where the scalar field is uniform. We extend this effective approach by allowing the Lagrangian in unitary gauge to depend on the time derivative of the lapse function. Although this dependence generically signals the presence of an extra scalar degree of freedom, theories that contain only one propagating scalar degree of freedom, in addition to the usual tensor modes, can be constructed by requiring the initial Lagrangian to be degenerate. Starting from a general quadratic action, we derive the dispersion relations for the linear perturbations around Minkowski and a cosmological background. Our analysis directly applies to the recently introduced Degenerate Higher-Order Scalar-Tensor (DHOST) theories. For these theories, we find that one cannot recover a Poisson-like equation in the static linear regime except for the subclass that includes the Horndeski and so-called \"beyond Horndeski\" theories. We also discuss Lorentz-breaking models inspired by Horava gravity. | 162,019 |
title: Coherence effects in electromagnetically induced transparency in V-type systems of 87Rb.; abstract: We present a theoretical and experimental study of electromagnetically induced transparency (EIT) in V-type systems of 87Rb atoms. We calculate accurate lineshapes of V-type EIT spectra by solving density matrix equations considering all the magnetic sublevels involved. The calculated spectra demonstrate consistency with the experimental results. We identify the coherence effect in the calculated EIT spectra, and determine that the coherence effect exists only in the cycling transition. We explain the reason for the suppression of the coherence effect in open transitions using an analytical calculation of the spectra for a simple V-type three-level atomic system. | 162,020 |
title: A CAMAC controller for the limited streamer tube readout; abstract: Abstract A controller is described for the limited streamer tube readout. It can handle up to 8192 channels organized in 8 buses at a rate of 5 MHz. The time required to collect and store all the data in memories is 5 μs. The data are then available to be read out via CAMAC in DMA mode by a computer. | 162,021 |
title: Characteristics and optimization of the two‐photon‐excited 16‐μm laser in 14NH3; abstract: Stimulated emission at 15.88 and 15.95 μm has been obtained in 14NH3 utilizing two‐photon excitation. Total output energies on the order of 1 mJ have been observed in configurations which can be readily scaled to higher values. A discussion of the parameters available to control the operation of this system is given along with experimental data on laser output energy, divergence, the role of the optical Stark effect, pressure dependence, and spectral control with absorbing gases. These mechanisms can be generally applied for efficient down‐conversion throughout the infrared. | 162,022 |
title: AN OBSERVATIONAL IMPRINT OF THE COLLAPSAR MODEL OF LONG GAMMA-RAY BURSTS; abstract: The Collapsar model provides a theoretical framework for the well-known association between long gamma-ray bursts (GRBs) and collapsing massive stars. A bipolar relativistic jet, launched at the core of a collapsing star, drills its way through the stellar envelope and breaks out of the surface before producing the observed gamma rays. While a wealth of observations associate GRBs with the death of massive stars, as yet there is no direct evidence for the Collapsar model itself. Here we show that a distinct signature of the Collapsar model is the appearance of a plateau in the duration distribution of the prompt GRB emission at times much shorter than the typical breakout time of the jet. This plateau is evident in the data of all three major satellites. Our findings provide evidence that directly supports the Collapsar model. In addition, the model suggests the existence of a large population of choked (failed) GRBs, and implies that the 2 s duration commonly used to separate Collapsars and non-Collapsars is inconsistent with the duration distributions of Swift and Fermi GRBs and only holds for BATSE GRBs. | 162,023 |
title: Dark Matter, Baryogenesis and Neutrino Oscillations from Right Handed Neutrinos; abstract: We show that, leaving aside accelerated cosmic expansion, all experimental data in high energy physics that are commonly agreed to require physics beyond the Standard Model can be explained when completing the model by three right-handed neutrinos that can be searched for using present-day experimental techniques. The model that realizes this scenario is known as the Neutrino Minimal Standard Model (nu MSM). In this article we give a comprehensive summary of all known constraints in the nu MSM, along with a pedagogical introduction to the model. We present the first complete quantitative study of the parameter space of the model where no physics beyond the nu MSM is needed to simultaneously explain neutrino oscillations, dark matter, and the baryon asymmetry of the Universe. The key new point of our analysis is leptogenesis after sphaleron freeze-out, which leads to resonant dark matter production, thus evading the constraints on sterile neutrino dark matter from structure formation and x-ray searches. This requires one to track the time evolution of left-and right-handed neutrino abundances from hot big bang initial conditions down to temperatures below the QCD scale. We find that the interplay of resonant amplifications, CP-violating flavor oscillations, scatterings, and decays leads to a number of previously unknown constraints on the sterile neutrino properties. We furthermore reanalyze bounds from past collider experiments and big bang nucleosynthesis in the face of recent evidence for a nonzero neutrino mixing angle theta(13). We combine all our results with existing constraints on dark matter properties from astrophysics and cosmology. Our results provide a guideline for future experimental searches for sterile neutrinos. A summary of the constraints on sterile neutrino masses and mixings has appeared in Canetti et al. [Phys. Rev. Lett. 110, 061801 (2013)]. In this article we provide all details of our calculations and give constraints on other model parameters. | 162,024 |
title: Small particles, big impacts: A review of the diverse applications of nanofluids; abstract: Nanofluids—a simple product of the emerging world of nanotechnology—are suspensions of nanoparticles (nominally 1–100 nm in size) in conventional base fluids such as water, oils, or glycols. Nanofluids have seen enormous growth in popularity since they were proposed by Choi in 1995. In the year 2011 alone, there were nearly 700 research articles where the term nanofluid was used in the title, showing rapid growth from 2006 (175) and 2001 (10). The first decade of nanofluid research was primarily focused on measuring and modeling fundamental thermophysical properties of nanofluids (thermal conductivity, density, viscosity, heat transfer coefficient). Recent research, however, explores the performance of nanofluids in a wide variety of other applications. Analyzing the available body of research to date, this article presents recent trends and future possibilities for nanofluids research and suggests which applications will see the most significant improvement from employing nanofluids. | 162,025 |
title: The linked dipole chain model for DIS; abstract: Abstract The Linked Dipole Chain Model provides an interpolation between the regions of high Q 2 (DGLAP) and low x moderate Q 2 (BFKL) in DIS. It is a reformulation and a generalization of the results obtained by Ciafaloni, Catani, Fiorani and Marchesini, and it gives a unified treatment of “normal DIS”, boson-gluon fusion events and hard subcollisions in resolved photon-proton scattering. Thus the formalism provides a complete picture which incorporates all hard or semihard hadronic interactions in a simple way, which is suitable for a Monte Carlo treatment of both structure functions and final state properties. We also discuss non-leading effects which significantly reduce the increase of the structure function for very small x -values. | 162,026 |
title: Role of step edges in oxygen vacancy transport into SrTiO3(001); abstract: Using a combination of oblique-incidence optical reflectivity difference and specular reflection high energy electron diffraction techniques, we studied vacuum annealing of pulsed-laser deposited Nb-doped SrTiO3 monolayers on SrTiO3(100) near 730°C. In oxygen-free ambient, the as-grown monolayers are oxygen deficient. The excess oxygen vacancies in the monolayers are reduced by vacancy diffusion into the bulk. We found that the reduction rate is characterized by an activation energy E=1.0eV. More interestingly, the pre-exponential factor decreases significantly as the annealing time interval increases between two successive monolayer depositions. We propose that the indiffusion of excess surface oxygen vacancies takes place at step edges, and the Oswald ripening governs the density of the latter during vacuum annealing. | 162,027 |
title: Suppression of instantons as the origin of quark confinement; abstract: Abstract Strong quark and/or gluon fields suppress instantons and are therefore expelled from the vacuum. Arguments are also given that instantons are really suppressed inside hadrons. | 162,028 |
title: Physics with the KLOE-2 experiment at the upgraded DA Phi NE; abstract: Investigation at a f-factory can shed light on several debated issues in particle physics. We discuss: (i) recent theoretical development and experimental progress in kaon physics relevant for the Standard Model tests in the flavor sector, (ii) the sensitivity we can reach in probing CPT and Quantum Mechanics from time evolution of entangled-kaon states, (iii) the interest for improving on the present measurements of non-leptonic and radiative decays of kaons and eta/eta\u0027 mesons, (iv) the contribution to understand the nature of light scalar mesons, and (v) the opportunity to search for narrow di-lepton resonances suggested by recent models proposing a hidden dark-matter sector. We also report on the e(+)e(-) physics in the continuum with the measurements of (multi) hadronic cross sections and the study of gamma gamma processes. | 162,029 |
title: On a possible alignment of elementary spin vectors in astronomical bodies; abstract: Under the hypothesis that astronomical bodies tend to align the spin vectors of their internal magnetic dipoles parallel to the rotation axis in order to increase the entropy by decreasing the rotational energy, we derived the magnetic fields of the known magnetic bodies in the Solar system. The calculated values, which span over 17 orders of magnitude, agree fairly well with the measured ones, despite the fact that elementary dipoles responsible for the magnetic fields that predominate in terrestrial bodies differ from those predominant in the Jovian planets, and both types differ from those predominant in the Sun. | 162,030 |
title: The Rayleigh-Bénard problem in intermediate bounded domains; abstract: The stationary instabilities of flow patterns associated with Rayleigh-BCnard convection in a 3 x 1 x 9 rectangular container are extensively investigated by numerical simulation. Two types of spatial instabilities of the base convection rolls are predicted in the transition from steady two-dimensional flow to the unsteady oscillatory regime; these instabilities depend on the Prandtl number. For Pr = 0.71 the soft-roll instability is found at moderate Rayleigh number Ra. The results obtained confirm the importance of this flow pattern as a continuous mechanism for steady transition from one wavenumber to another. For Pr = 15, cross-roll instability is obtained, which at larger Ra leads to bimodal conuection. For this value of Pr the soft-roll flow pattern is found at intermediate Ra. At higher Ra a new flow structure in which cross-rolls are superimposed on the soft roll is obtained. The effects of the various flow structures on the heat transfer are given. A quantitative comparison with previous experimental and theoretical findings is also presented and discussed. | 162,031 |
title: Higgs boson production and decay: Effects from light third generation and vectorlike matter; abstract: We study the implications of light third generation sparticles on the production cross section and decay widths of a light $CP$-even Higgs boson. For simplicity, we consider scenarios in which only one of the sfermions from the third generation is light. For each case, we attempt to explain the apparently large enhancement in the Higgs production and decay in the diphoton channel with small deviations in the $ZZ$ channel. In the minimal supersymmetric standard model (MSSM) framework we find that only a light stau can explain these observations while keeping the lightest $CP$-even Higgs boson mass in the interval $123\\text{ }\\text{ }\\mathrm{GeV}\\ensuremath{\\lesssim}{m}_{h}\\ensuremath{\\lesssim}127\\text{ }\\text{ }\\mathrm{GeV}$. For the light stop scenario, the observations related to the diphoton and $ZZ$ channel can be accommodated but, in order to satisfy the Higgs mass bound, one needs to go beyond the MSSM. In particular, we invoke vectorlike particles with masses around a TeV. These new particles preserve gauge coupling unification and provide additional contributions to the Higgs mass. With these new contributions a 126 GeV Higgs mass is easily achieved. We also find that with only a light sbottom quark, the above mentioned excess is hard to accommodate. | 162,032 |
title: Quark condensate and deviations from string-like behaviour of meson spectra; abstract: Abstract I analyze the hypothesis that deviations from the linear meson mass spectra appear due to the dynamical chiral symmetry breaking in QCD. It is shown that the linear mass spectrum for the light, non-strange vector and axial-vector mesons is then parametrized by the constant f π , being successful phenomenologically. The toy model for deviations from linearity is proposed. | 162,033 |
title: Compact objects and the swampland; abstract: Recently, two simple criteria were proposed to assess if vacua emerging from an effective scalar field theory are part of the string \"landscape\" or \"swampland\". The former are the vacua that emerge from string compactifications; the latter are not obtained by any such compactification and hence may not survive in a UV completed theory of gravity. So far, these criteria have been applied to inflationary and dark energy models. Here we consider them in the context of solitonic compact objects made up of scalar fields: boson stars. Analysing several models (static, rotating, with and without self-interactions), we find that, in this context, the criteria are not independent. Furthermore, we find the universal behaviour that in the region wherein the boson stars are expected to be perturbatively stable, the compact objects may be part of the landscape. By contrast, in the region where they may be faithful black hole mimickers, in the sense they possess a light ring, the criteria fail (are obeyed) for static (rotating) ultracompact boson stars, which should thus be part of the swampland (landscape). We also consider hairy black holes interpolating between these boson stars and the Kerr solution and establish the part of the domain of existence where the swampland criteria are violated. In interpreting these results one should bear in mind, however, that the swampland criteria are not quantitatively strict. | 162,034 |
title: Two dimensional soliton energy and ESR in AFM; abstract: Abstract The energy E ′ ≡ E /( JS 2 )=4π+ϵ=12.6+ϵ for static 2-d solitons in classical Heisenberg magnets ( J S i S k ) with weak easy-axis anisotropy ( DS 2 z ) is calculated. It agrees with E ′ =1.7±1.2 found by reinterpreting ESR lien broadening in antiferromagnets according to the Arrhenius law. | 162,035 |
title: Evolution of transverse piezoelectric response of lead zirconate titanate ceramics under hydrostatic pressure; abstract: The piezoelectric properties of 31-mode resonators of lead zirconate titanate ceramics under hydrostatic pressure from 0.1 to 325 MPa were evaluated by a fitting method, in which mechanical loss was taken into account. Our results based on the fitting method showed a hydrostatic pressure independent tendency of the piezoelectric coefficient and the electromechanical coupling factor because the adopted PZT ceramic can be considered as a linear system in our experiment, while two misleading tendencies of piezoelectric coefficient were obtained based on the resonance method when ignoring the contribution of the mechanical loss. | 162,036 |
title: Magnetic properties of GdFe2Ge2; abstract: Abstract We have studied the magnetic properties of the antiferromagnetic body-centred tetragonal compound GdFe2Ge2 by means of DC susceptibility, high-field free powder and specific heat measurements in high magnetic fields. The magnetic measurements indicate a significant contribution of the non-4f electrons to the magnetic properties of the compound. The magnetisation and the zero-field specific heat data can be described satisfactorily in a generalised molecular-field model based upon equal-moment modes for Gd moments interacting with an itinerant-electron band. | 162,037 |
title: The η, η′, η c mixing angles and SU(4); abstract: In this paper, we study the quark contents of the η, η′ and ηc pseudoscalar mesons using SU(4) mass breaking formalism. We predict a mass value form\n\n η\n c\n close to the one obtained by the Crystal Ball experiment at SLAC. Our analysis favors the linear mass formula rather than the quadratic one. A definite prediction for the value m\n η\n c\n makes this experiment feasible. | 162,038 |
title: Design of a Mach-Zehnder interferometer for the measurement of electrostrictive strains; abstract: The investigation of quadratic electrostriction of non-ferroelectric crystals is interesting from a fundamental point of view, because this phenomenon of electromechanical interaction has not yet been completely elucidated. The extreme smallness of the dilatations that have to be measured ( m) has made the development of advanced interferometric systems necessary. Here, a new design concept of a double Mach - Zehnder interferometer is presented that allows one to apply a null method. | 162,039 |
title: General functional relation between nucleon momentum and density distributions in nuclei; abstract: It is shown on the basis of the Hohenberg-Kohn theorem that the nucleon momentum distribution is an unique functional of the local density distribution. A theoretical scheme in which density and momentum distributions enter equivalently as fundamental variables of the theory is suggested. The form of the momentum distribution proposed in the coherent density fluctuation model as a functional of the local density and its relation with the suggested theoretical scheme are discussed. | 162,040 |
title: HIJING 1.0: A Monte Carlo program for parton and particle production in high energy hadronic and nuclear collisions; abstract: Based on QCD-inspired models for multiple jets production, we developed a Monte Carlo program to study jet and the associated particle production in high energy pp, pA and AA collisions. The physics behind the program which includes multiple minijet production, soft excitation, nuclear shadowing of parton distribution functions and jet interaction in dense matter is briefly discussed. A detailed description of the program and instructions on how to use it are given. | 162,041 |
title: On the Flow Induced by Centrifugal Buoyancy in a Differentially-Heated Rotating Cylinder; abstract: We consider the nature of thermally stratified flow in a closed cylinder rotating about the direction of gravity under conditions appropriate for terrestrial laboratory experiments. Motion is driven by centrifugal buoyancy, with outflow near the cold disk and inflow near the hot disk. Although similarity solutions for the infinite disk open-geometry problem exist and are easily found, even analytically in certain limits, there remain questions about the applicability of these spatially simplified models in a closed geometry with a vertical sidewall. This paper compares theoretical self-similar core solutions with computational simulations constructed to satisfy a wide range of sidewall thermal boundary conditions; insulating, conducting (with a linear temperature profile up the wall), hot (isothermal), or cold. The width of penetration of sidewall influence in toward the axis of rotation depends on the sidewall thermal boundary condition. However, as the cylinder radius is increased for a fixed height, a substantial region of the container about the axis is accurately described by the thermocline solutions of the theory. The non-self-similar region at large radius can include separation of the lower outflow boundary layer, a feature not evident in previous studies of this problem. | 162,042 |
title: Cluster structure of a low-energy resonance in tetraneutron; abstract: We theoretically investigate the possibility for a tetraneutron to exist as a low-energy resonance state. We explore a microscopic model based on the assumption that the tetraneutron can be treated as a compound system, where 3n + n and 2n + 2n coupled cluster configurations coexist. The influence of the Pauli principle on the kinetic energy of the relative motion of the neutron clusters is shown to result in their attraction. The strength of such attraction is high enough to ensure the existence of a low-energy resonance in the tetraneutron, provided that the oscillator length is large enough. | 162,043 |
title: Relativistic Hartree-Fock model with bare nucleon-nucleon interaction for neutron-rich matter; abstract: Abstract We study neutron-rich matter in the relativistic Hartree–Fock model (RHF) with the bare nucleon–nucleon interaction. As an important ingredient, we take into account the short range correlation in terms of the unitary correlation operator method (UCOM). We calculate the equations of state (EOS) of neutron-rich matter with Bonn potential. Our results on neutron-rich matter compare very nicely with those in the Relativistic Brueckner–Hartree–Fock (RBHF) theory. On the other hand, when we apply the RHF model with the UCOM on symmetric nuclear matter, the EOS is largely different from the RBHF result particularly in the low density region. This is because the other important ingredient as the tensor interaction plays important role in symmetric nuclear matter. We also discuss the proton and neutron Dirac masses in neutron-rich matter and find that the proton Dirac mass is larger than the neutron mass in agreement with the RBHF theory using projection techniques. | 162,044 |
title: Chaotic Rayleigh-Bénard convection with finite sidewalls.; abstract: We explore the role of finite sidewalls on chaotic Rayleigh-Benard convection. We use large-scale parallel spectral-element numerical simulations for the precise conditions of experiment for cylindrical convection domains. We solve the Boussinesq equations for thermal convection and the conjugate heat transfer problem for the energy transfer at the solid sidewalls of the cylindrical domain. The solid sidewall of the convection domain has finite values of thickness, thermal conductivity, and thermal diffusivity. We compute the Lyapunov vectors and exponents for the entire fluid-solid coupled problem. We quantify the chaotic dynamics of convection over a range of thermal sidewall boundary conditions. We find that the dynamics become less chaotic as the thermal conductivity of the sidewalls increases as measured by the value of the fractal dimension of the dynamics. The thermal conductivity of the sidewall is a stabilizing influence; the heat transfer between the fluid and solid regions is always in the direction to reduce the fluid motion near the sidewalls. Although the heat interaction for strongly conducting sidewalls is only about 1% of the heat transfer through the fluid layer, it is sufficient to reduce the fractal dimension of the dynamics by approximately 25% in our computations. | 162,045 |
title: Analytical On-shell Calculation of Low Energy Higher Order Scattering; abstract: We demonstrate that the use of analytical on-shell methods involving calculation of the discontinuity across the t-channel cut associated with the exchange of a pair of massless particles (photons or gravitons) can be used to evaluate one-loop contributions to electromagnetic and gravitational scattering, with and without polarizability, reproducing via simple algebraic manipulations, results obtained previously, generally using Feynman diagram techniques. In the gravitational case the use of factorization permits a straightforward and algebraic calculation of higher order scattering without consideration of ghost contributions or of triple-graviton couplings, which made previous evaluations considerably more arduous. | 162,046 |
title: Selective Reflection of Potassium Vapor Nanolayers in a Magnetic Field; abstract: The selective reflection of laser radiation from the interface between a dielectric window and the atomic vapors confined in a nanocell of thickness L ≈ 350 nm is used to develop effective Doppler-broadening- free spectroscopy of potassium atoms. A small atomic line width and a relation between the signal intensity and the transition probability allowed us to resolve four lines of atomic transitions responsible for the D1 lines of the 39K and 41K isotopes. Two groups containing four atomic transitions form in an applied magnetic field upon pumping by radiation with circular polarization σ+ or σ–. Different intensities (probabilities) of transitions for the σ+ and σ– excitations are detected in magnetic field B0 ≈ A hfs /μB ≈ 165 G (A hfs is the magnetic dipole constant for the ground state and μB is the Bohr magneton). A substantially different situation is observed at B ≫ B0, since high symmetry appears for the two groups formed by radiation with circular polarization σ+ or σ–. Each group is the mirror image of the other group with respect to the frequency of the 42S1/2–42P1/2 transition, which additionally proves the occurrence of the complete Paschen–Back regime of the hyperfine structure at B ≈ 2.5 kG. A developed theoretical model well reproduces the experimental results. Possible practical applications are described. The results obtained can also be applied to the D1 lines of 87Rb and 23Na. | 162,047 |
title: The Metrology Light Source – The new dedicated electron storage ring of PTB ☆; abstract: Abstract The Physikalisch-Technische Bundesanstalt (PTB) is currently constructing a low-energy electron storage ring in the close vicinity of BESSY II where PTB operates a laboratory for synchrotron-radiation-based metrology, mainly in the X-ray spectral region. The new storage ring, which is called ‘Metrology Light Source’ (MLS), will mainly be dedicated to radiometry and technological development in the UV, VUV and EUV spectral range and will thus fill the gap in the spectral range that has opened up since the shut-down of BESSY I. Moreover, the MLS will deliver intense radiation in the IR and FIR/THz spectral range. The MLS can be operated with parameters optimized for special calibration tasks, which, at a multi-user facility such as BESSY II, is rarely possible. The electron energy can be tuned in the range from 200 MeV up to 600 MeV and the electron beam current can be adjusted from 1 pA (single electron) up to 200 mA. All relevant storage ring parameters can be measured with high accuracy, thus making the MLS a source of calculable synchrotron radiation, i.e. a primary source standard. The MLS is designed in close co-operation with the BESSY GmbH, construction has started in the autumn of 2004 and user operation is scheduled to begin in 2008. | 162,048 |
title: Variational multiparticle-multihole configuration mixing method applied to pairing correlations in nuclei; abstract: Applying a variational multiparticle-multihole configuration mixing method whose purpose is to include correlations beyond the mean field in a unified way without particle number and Pauli principle violations, we investigate pairing-like correlations in the ground states of {sup 116}Sn, {sup 106}Sn, and {sup 100}Sn. The same effective nucleon-nucleon interaction, namely, the D1S parametrization of the Gogny force, is used to derive both the mean field and correlation components of nuclear wave functions. Calculations are performed using an axially symmetric representation. The structure of correlated wave functions, their convergence with respect to the number of particle-hole excitations, and the influence of correlations on single-particle level spectra and occupation probabilities are analyzed and compared with results obtained with the same two-body effective interaction from BCS, Hartree-Fock-Bogoliubov, and particle number projected after variation BCS approaches. Calculations of nuclear radii and the first theoretical excited 0{sup +} states are compared with experimental data. | 162,049 |
title: Four-dimensional CDT with toroidal topology; abstract: Abstract 3 + 1 dimensional Causal Dynamical Triangulations (CDT) describe a quantum theory of fluctuating geometries without the introduction of a background geometry. If the topology of space is constrained to be that of a three-dimensional torus we show that the system will fluctuate around a dynamically formed background geometry which can be understood from a simple minisuperspace action which contains both a classical part and a quantum part. We determine this action by integrating out degrees of freedom in the full model, as well as by transfer matrix methods. | 162,050 |
title: Models of Dynamical R-Parity Violation; abstract: The presence of R-parity violating interactions may relieve the tension be- tween existing LHC constraints and natural supersymmetry. In this paper we lay down the theoretical framework and explore models of dynamical R-parity violation in which the breaking of R-parity is communicated to the visible sector by heavy messenger fields. We find that R-parity violation is often dominated by non-holomorphic operators that have so far been largely ignored, and might require a modification of the existing searches at the LHC. The dynamical origin implies that the eects of such operators are suppressed by the ratio of either the light fermion masses or the supersymmetry breaking scale to the mediation scale, thereby providing a natural explanation for the smallness of R-parity violation. We consider various scenarios, classified by whether R-parity violation, flavor breaking and/or supersymmetry breaking are mediated by the same messenger fields. The most compact case, corresponding to a deformation of the so called flavor mediation sce- nario, allows for the mediation of supersymmetry breaking, R-parity breaking, and flavor symmetry breaking in a unified manner. | 162,051 |
title: The clustering of galaxies as a function of their photometrically estimated atomic gas content; abstract: We introduce a new photometric estimator of the H i mass fraction () in local galaxies, which is a linear combination of four parameters: stellar mass, stellar surface mass density, NUV-r colour and g-i colour gradient. It is calibrated using samples of nearby galaxies (0.025 \u003c z \u003c 0.05) with H i line detections from the GALEX Arecibo SDSS Survey (GASS) and Arecibo Legacy Fast ALFA (ALFALFA) surveys, and it is demonstrated to provide unbiased estimates even for H i-rich galaxies. We apply this estimator to a sample of similar to 24 000 galaxies from the Sloan Digital Sky Survey (SDSS)/Data Release 7 (DR7) in the same redshift range. We then bin these galaxies by stellar mass and H i mass fraction and compute projected two-point cross-correlation functions with respect to a reference galaxy sample. Results are compared with predictions from current semi-analytic models of galaxy formation. The agreement is good for galaxies with stellar masses larger than 1010 M?, but not for lower mass systems. We then extend the analysis by studying the bias in the clustering of H i-poor or H i-rich galaxies with respect to galaxies with normal H i content on scales between 100 kpc and similar to 5 Mpc. For the H i-deficient population, the strongest bias effects arise when the H i deficiency is defined in comparison to galaxies of the same stellar mass and size. This is not reproduced by the semi-analytic models, where the quenching of star formation in satellites occurs by starvation and does not depend on their internal structure. H i-rich galaxies with masses greater than 1010 M? are found to be antibiased compared to galaxies with normal H i content. Interestingly, no such effect is found for lower mass galaxies. | 162,052 |
title: Numerical Investigation of Thermofluid Flow Characteristics With Phase Change Against High Heat Flux in Porous Media; abstract: This study numerically evaluates thermofluid flow characteristics in porous medium by a newly developed \"modified two-phase mixture model\" applying Ergun\u0027s law and a two-energy model instead of a one-energy model. In a single-phase flow case, thermal nonequilibrium between a solid phase and a fluid phase is observed in the area where imposed heat conducts from a heating wall and further convective heat transfer is more active. The degree of thermal nonequilibrium has a positive correlation with the increase in flow velocity and heat flux input. In the case of two-phase flow, the thermal nonequilibrium is remarkable in the two-phase region because the solid-phase temperature in this region is far beyond saturation temperature. A difference between these two models is obvious especially in the two-phase flow case, so that the numerical simulation with the modified two-phase mixture model is indispensable under the high heat flux conditions of over 1 MW/m 2 . | 162,053 |
title: E1 strength of the subthreshold 3/2+ state in 15O studied by Coulomb excitation; abstract: Abstract The radiative width of the 3/2+ state at 6.793 MeV in 15O has been experimentally determined to be Γγ=0.95+0.60−0.95 eV by intermediate-energy Coulomb excitation. Our result independently supports the recent studies which point to a minor contribution of this state to the astrophysical rate of the 14N(p,γ)15O reaction in the CNO-cycle hydrogen burning in massive stars. | 162,054 |
title: Skyrmion model and the dynamical breakdown of chiral symmetry; abstract: A scalar field, $\\eta({\\bf r})$, is coupled to the skyrmion. Its classical value in the vacuum (\"condensate\") reduces to the pion decay constant, $f_{\\pi}$, being thus proportional to the chiral condensate $ $. A quadratic coupling of the scalar field to the pion kinetic Lagrangian term, reminiscent from the linear sigma model, is considered. Its mass is an additional free parameter in the model associated to the lightest scalar isoscalar meson. Solutions for the two resulting coupled differential equations are found in several cases. The nucleon, as a topological soliton, ``digs a hole\u0027\u0027 in the vacuum making the value of the scalar condensate to be close to zero inside the skyrmion. Some of the observables, as for example the baryon masses, may have their values closer to the experimental ones. Derrick\u0027s stability analysis is applied to the model. | 162,055 |
title: Characteristics of transonic spherical symmetric accretion flow in Schwarzschild-de Sitter and Schwarzschild anti-de Sitter backgrounds, in pseudo-general relativistic paradigm; abstract: In this paper, we present a complete work on steady state spherically symmetric Bondi type accretion flow in the presence of cosmological constant (Λ) in both Schwarzschild-de Sitter (SDS) and Schwarzschild anti-de Sitter (SADS) backgrounds considering an isolated supermassive black hole (SMBH), with the inclusion of a simple radiative transfer scheme, in the pseudo-general relativistic paradigm. We do an extensive analysis on the transonic behavior of the Bondi type accretion flow onto the cosmological BHs including a complete analysis of the global parameter space and the stability of flow, and do a complete study of the global family of solutions for a generic polytropic flow. Bondi type accretion flow in SADS background renders multiplicity in its transonic behavior with inner \"saddle\" type and outer \"center\" type sonic points, with the transonic solutions forming closed loops or contours. There is always a limiting value for ∣Λ∣ up to which we obtain valid stationary transonic solutions, which correspond to both SDS and SADS geometries; this limiting value moderately increases with the increasing radiative efficiency of the flow, especially correspond to Bondi type accretion flow in SADS background. Repulsive Λ suppresses the Bondi accretion rate by an order of magnitude for relativistic Bondi type accretion flow for a certain range in temperature, and with a marginal increase in the Bondi accretion rate if the corresponding accretion flow occurs in SADS background. However, for a strongly radiative Bondi type accretion flow with high mass accretion rate, the presence of cosmological constant do not much influence the corresponding Bondi accretion rate of the flow. Our analysis show that the relic cosmological constant has a substantial effect on Bondi type accretion flow onto isolated SMBHs and their transonic solutions beyond length-scale of kiloparsecs, especially if the Bondi type accretion occurs onto the host supergiant ellipticals or central dominant (CD) galaxies directly from ambient intercluster medium (ICM). However, for high mass accretion rate, the influence of cosmological constant on Bondi accretion dynamics, generically, diminishes. As active galactic nuclei (AGN)/ICM feedback can be advertently linked to Bondi type spherical accretion, any proper modeling of AGN feedback or megaparsecs-scale jet dynamics or accretion flow from ICM onto the central regions of host galaxies should take into account the relevant information of repulsive Λ, especially in context to supergiant elliptical galaxies or CD galaxies present in rich galaxy clusters. This could also explore the feasibility to limit the value of Λ, from the kinematics in local galactic-scales. | 162,056 |
title: Modeling inertial particle acceleration statistics in isotropic turbulence; abstract: Our objective is to explain recent Lagrangian acceleration measurements of inertial particles in decaying, nearly isotropic turbulence [Ayyalasomayajula et al., Phys. Rev. Lett. 97, 144507 (2006)]. These experiments showed that as particle inertial effects increased, the variance in the particle acceleration fluctuations was reduced, and the tails of the normalized particle acceleration probability density function (PDF) became systematically attenuated. We model this phenomenon using a base flow that consists of a two-dimensional array of evenly spaced vortices with signs and intensities that vary randomly in time. We simulate a large sample of inertial particles moving through the fluid without disturbing the flow (one-way coupling). Consistent with Bec et al. [J. Fluid Mech. 550, 349 we find that our model exhibits preferential concentration or clustering of particles in regions located away from the vortex centers. That is, inertial particles selectively sample the flow field, oversampling re... | 162,057 |
title: Radiative corrections to Bhabha scattering at high energies (I): Virtual and soft photon corrections; abstract: The complete set of formulas for the differential Bhabha cross section including all the one-loop virtual corrections and soft photon bremsstrahlung emission is presented for the standard model in an on-shell renormalization scheme. The influence and structure of the corrections are discussed below, on top and around, and far above the Z0 resonance. | 162,058 |
title: Comment on the heavy→light form factors; abstract: Abstract We propose a simple parameterization for the form factors in heavy to light decays, which satisfies the heavy quark scaling laws and avoids introducing the explicit “dipole” form. The illustration is provided with the set of lattice data for B → π semileptonic decay. The resulting shape of the form factor also agrees with the QCD sum rule predictions. | 162,059 |
title: Domain glasses: Twin planes, Bloch lines, and Bloch points; abstract: Ferroelastic materials can develop complex domain structures, which have properties of glassy systems (non-ergodicity, glass dynamics, glass transitions, and freezing). Four characteristic temperatures are defined for such domain glasses: the dynamical nucleation temperature Td where local correlated clusters can form glass states within a (tweed-) nano structure, To the Vogel–Fulcher temperature of these precursor nano-structures, Tpt the phase transition temperature where the (ferroelastic) transition occurs, and TK the Kauzmann temperature where the complex domain structure freezes. Td exists in most ferroelastic materials whereas the other transitions depend on the complexity of the domain patterns and hence on their thermal history. Shear collapse and rapid thermal quench of ferroelastic crystals preferentially lead to domain glasses whereas slow anneal produces mostly highly correlated pattern such as stripe patterns or single domain crystals. Domain glasses are compared with structural glasses and several examples for domain glass features are discussed. | 162,060 |
title: Resolution enhancement in noise spectrum by using velocity selective optical pumping in cesium vapor; abstract: We demonstrate experimentally that the resolution of amplitude noise spectrum in Cs atomic vapor can be enhanced by narrowing the absorption using velocity selective optical pumping technique. It is found that the steep atomic dispersion accompanied by high absorption leads to more conversion of laser phase noise to amplitude noise, when the field propagates throughout the atoms, and meanwhile the spectral resolution is improved. The effect of optical pumping intensity on the spectrum resolution is experimentally discussed, and a theoretical explanation for this phenomenon is given, which shows that the phase-to-amplitude noise conversion is directly proportional to the dispersion of medium. | 162,061 |
title: Fabrication and optical characterization of the normal metal hot-electron microbolometer with Andreev mirrors; abstract: Abstract The normal metal hot-electron microbolometer (NHEB) is a direct detector for mm and sub-mm wavelengths. Theoretical estimations indicate that such a device should be able to achieve a sensitivity of around 10 −17 W/(Hz) 1/2 at 0.3 K and a time constant less than 1 μs. The temperature of the electron gas is monitored using superconductor–insulator–normal metal (SIN/NIS) tunnel junctions. We have fabricated such an NHEB where the normal metal strip is coupled to a double slot antenna for optical qualification (normal metal strip size (5.6×0.25×0.03) μm 3 ). The antenna is designed for 300 GHz and has an impedance of 30 Ω at the center frequency. The actual optical responsitivity and the response time of our NHEB has been measured at 0.5 K using a hot/cold load (black body radiation at room temperature and at liquid nitrogen temperature). DC-current measurements performed on other samples earlier indicate that our NHEB can achieve an electrical noise equivalent power (NEP) of at least 3×10 −16 W/(Hz) 1/2 . We conclude that the optical responsitivity value obtained in the measurement is consistent with the electrical NEP value at the same temperature and in agreement with the estimated efficiency of the quasioptical coupling. | 162,062 |
title: On the direct detection of multi-component dark matter: sensitivity studies and parameter estimation; abstract: We study the case of multi-component dark matter, in particular how direct detection signals are modified in the presence of several stable weakly-interacting-massive particles. Assuming a positive signal in a future direct detection experiment, stemming from two dark matter components, we study the region in parameter space where it is possible to distinguish a one from a two-component dark matter spectrum. First, we leave as free parameters the two dark matter masses and show that the two hypotheses can be significantly discriminated for a range of dark matter masses with their splitting being the critical factor. We then investigate how including the effects of different interaction strengths, local densities or velocity dispersions for the two components modifies these conclusions. We also consider the case of isospin-violating couplings. In all scenarios, we show results for various types of nuclei both for elastic spin-independent and spin-dependent interactions. Finally, assuming that the two-component hypothesis is confirmed, we quantify the accuracy with which the parameters can be extracted and discuss the different degeneracies that occur. This includes studying the case in which only a single experiment observes a signal, and also the scenario of having two signals from two different experiments, in which case the ratios of the couplings to neutrons and protons may also be extracted. | 162,063 |
title: Feynman Path Integral approach to electron diffraction for one and two slits, analytical results; abstract: In this article we present an analytic solution of the famous problem of diffraction and interference of electrons through one and two slits (for simplicity, only the one-dimensional case is considered). In addition to exact formulas, we exhibit various approximations of the electron distribution which facilitate the interpretation of the results. Our derivation is based on the Feynman path integral formula and this work could therefore also serve as an interesting pedagogical introduction to Feynman\u0027s formulation of quantum mechanics for university students dealing with the foundations of quantum mechanics. | 162,064 |
title: Status report on the GSI on-line mass separator facility; abstract: Abstract The status of the GSI mass separator facility on-line to the heavy-ion accelerator UNILAC at Darmstadt is described, covering the technical development since the start of operation in 1976. | 162,065 |
title: Empirical transverse charge densities in the nucleon-to-P(11)(1440) transition; abstract: Abstract Using recent experimental data, we analyze the electromagnetic transition from the nucleon to the P 11 ( 1440 ) resonance. From the resulting empirical transition form factors, we map out the quark transverse charge densities which induce the N → P 11 ( 1440 ) transition. It is found that the transition from the proton to its first radially excited state is dominated by up quarks in a central region of around 0.5 fm and by down quarks in an outer band which extends up to about 1 fm. | 162,066 |
title: The atmosphere of Uranus; abstract: Current knowledge of the atmosphere of Uranus is reviewed and specific objectives are suggested for satellite missions to Uranus. The anomalous composition of Uranus makes determinations of its atmospheric composition particularly valuable for testing theories of solar system evolution. The weakness of its atmospheric heating makes the determination of its atmospheric structure and dynamics particularly valuable for testing theories of atmospheric behavior. The large axial inclination of Uranus implies an anomalous latitudinal variation of temperature and dynamics different from that of the other planets. | 162,067 |
title: Multiplet Theory for Conduction Band Edge and O-Vacancy Defect States in SiO2, Si3N4, and Si Oxynitride Alloy Thin Films; abstract: This article, the second of a two-part sequence, combines X-ray absorption spectroscopy (XAS) and many-electron theory to develop a model for intrinsic bonding defects in non-crystalline and nanocrystalline thin films used primarily as gate dielectrics for field effect transistors and related devices. In SiO2 these defects are O-atom vacancies and their spectral features in O K pre-edge spectra are assigned to multiplet transitions based on a d2 model for the electrons in a neutral O-vacancy site. This model is applied to (i) non-crystalline (nc-) SiO2, and extended to (ii) Si oxynitride alloys, (nc-SiO2)1-x(Si3N4)x, and nc-Hf Si oxynitrides. As in Part I, this relies on Tanabe–Sugano (TS) energy diagrams to identify spin-allowed X-ray transitions and negative ion states. Differences between band edge states in (i) nc-SiO2, and (ii) nc-Si3N4 explain quantitative differences in trapping and trap-assisted tunneling. Preliminary results for nc-GeO2 films prepared by remote-plasma-enhanced chemical vapor deposition shows these films exhibit surface stability similar to nc-SiO2, suggesting that local nc-GeO2 bonding involves the same 4-fold Ge, and 2-fold O coordination as Si and O in nc-SiO2. | 162,068 |
title: Probing vacuum birefringence by phase-contrast Fourier imaging under fields of high-intensity lasers; abstract: In vacuum high-intensity lasers can cause photon–photon interaction via the process of virtual vacuum polarization which may be measured by the phase velocity shift of photons across intense fields. In the optical frequency domain, the photon–photon interaction is polarization-mediated described by the Euler–Heisenberg effective action. This theory predicts the vacuum birefringence or polarization dependence of the phase velocity shift arising from nonlinear properties in quantum electrodynamics (QED). We suggest a method to measure the vacuum birefringence under intense optical laser fields based on the absolute phase velocity shift by phase-contrast Fourier imaging. The method may serve for observing effects even beyond the QED vacuum polarization. | 162,069 |
title: Temporal diagnostics of femtosecond electron bunches with complex structures using sparsity-based algorithm; abstract: Femtosecond electron bunches with complex temporal structures play a crucial role in THz generation, free-electron lasers and plasma wakefield accelerators. The ultrashort electron pulse duration can be reconstructed from the coherent transition radiation (CTR) spectrum based on prior knowledge. A weighted greedy sparse phase retrieval (WGESPAR) algorithm is developed to reduce the ambiguities for reconstructing the distribution of the beam current. This algorithm achieves better performance than iterative algorithms, especially for truncated noisy spectra of multibunch structures. Based on the WGESPAR algorithm, the complex temporal structures of femtosecond electron bunches generated from laser wakefield accelerators can be successfully reconstructed. | 162,070 |
title: Electronic structure and orbital ordering in perovskite-type 3d transition-metal oxides studied by Hartree-Fock band-structure calculations.; abstract: We have studied transition-metal 3d-oxygen 2p lattice models, where full degeneracy of transition-metal 3d and oxygen 2p orbitals and on-site Coulomb and exchange interactions between 3d electrons are taken into account, by means of a spin- and orbital-unrestricted Hartree-Fock (HF) approximation. The electronic-structure parameters deduced from the cluster-model analyses of the photoemission spectra are used as input. We have applied this method to perovskite-type 3d transition-metal oxides, which exhibit various electrical and magnetic properties. It is shown that the HF results can explain the ground-state properties of insulating oxides. The relationship between spin- and orbital-ordered solutions and the Jahn-Teller-type and ${\\mathrm{GdFeO}}_{3}$-type distortions in R${\\mathrm{TiO}}_{3}$, R${\\mathrm{VO}}_{3}$, R${\\mathrm{MnO}}_{3}$, and R${\\mathrm{NiO}}_{3}$ (R is a rare earth atom or Y) is extensively studied. Single-particle excitation spectra calculated using Koopmans\u0027 theorem give us an approximate but relevant picture on the electronic structure of the perovskite-type 3d transition-metal oxides. As a drawback, the HF calculations tend to overestimate the magnitude of the band gap compared with the experimental results and to predict some paramagnetic metals as antiferromagnetic insulators. \\textcopyright{} 1996 The American Physical Society. | 162,071 |
title: Relativistic Spontaneous Localization: A Proposal; abstract: A new proposal for a Lorentz-invariant spontaneous localization process in the framework of relativistic quantum field theory is presented. As in all dynamical reduction models, a stochastic process is introduced, which drives the state vector towards the eigenspaces of a set of operators representing suitably chosen physical quantities. Such operators constitute a Lorentz scalar field and are built as time averages and space integrals of a local field-theoretic operator in such a way that the quantities they represent acquire a macroscopic character. As always in dynamical reduction theories, the action of the process on microscopic systems takes place via the micro-macro correlations which arise, e.g., as a consequence of measurements. | 162,072 |
title: Bound-state effects on kinematical distributions of top quarks at hadron colliders; abstract: First we present a theoretical framework to compute the fully differential cross sections for the top-quark productions and their subsequent decays at hadron colliders, incorporating the bound-state effects which are important in the \\( t\\bar{t} \\) threshold region. We include the bound-state effects such that the cross sections are correct in the LO approximation both in the threshold and high-energy regions. Then, based on this framework we compute various kinematical distributions of top quarks as well as of their decay products at the LHC, by means of Monte-Carlo event-generation. These are compared with the corresponding predictions based on conventional perturbative QCD. In particular, we find a characteristic bound-state effect on the \\( \\left( {b{W^{+} }} \\right){ - }\\left( {\\bar{b}{W^{-} }} \\right) \\) double-invariant-mass distribution, which is deformed to the lower invariant-mass side in a correlated manner. | 162,073 |
title: Growth and optical properties of SrBi2Nb2O9 ferroelectric thin films using pulsed laser deposition; abstract: High quality SrBi2Nb2O9 ferroelectric thin films were fabricated on platinized silicon using pulsed laser deposition assisted with dc glow discharge plasma. Microstructure and ferroelectric properties of the films were characterized. Optical properties of the thin films were studied by spectroscopic ellipsometry and photoluminescence from the ultraviolet to the infrared region. Optical constants, n∼0.56 in the infrared region and n∼2.24 in the visible spectral region, were determined through multilayer analyses on their respective pseudodielectric functions. The band-gap energy is estimated to be 3.60 eV. A photoluminescence peak at 0.78 μm, whose intensity decreases with decreasing temperature, was observed when excited with subband-gap energy (2.41 eV). This emission process may involve intermediate defect states at the crystallite boundaries. A possible mechanism for the observed photoluminescence, a Nb4+–O− exciton in the NbO6 octahedron, is discussed. | 162,074 |
title: An introduction to the BABAR experiment; abstract: Abstract The goals of the BABAR experiment and the means of achieving them are discussed. The proposed detector is described in some detail, and an example analysis is outlined. The expected sensitivity of the experiment in the various channels is summarised. | 162,075 |
title: DISCOVERY OF PULSED gamma-RAYS FROM THE YOUNG RADIO PULSAR PSR J1028-5819 WITH THE FERMI LARGE AREA TELESCOPE; abstract: Radio pulsar PSR J1028-5819 was recently discovered in a high-frequency search (at 3.1 GHz) in the error circle of the Energetic Gamma-Ray Experiment Telescope (EGRET) source 3EG J1027-5817. The sp ... | 162,076 |
title: Dielectric Relaxation in Confined Ferroelectric Polymer; abstract: The dynamics of segmental and chain motions in poly(vinylidene fluoride) confined to anodized aluminum oxide nanopores by melt-wetting was studied by broad-band dielectric spectroscopy. Molecular structure of the confined polymer was studied by means of wide-angle X-ray scattering in the transmission mode with ψ scanning. The confined polymer was found to form multilayered cylindrical mesostructure containing three polymorphs with the direction of nonpolar polymorph II aligned along the pore channels. The relaxation rates of segmental motions in the amorphous phase of the polymer were found to be shorter in confined geometry than in the bulk, whereas the relaxation of the local mode was found to be broadened due to inhomogeneous relaxation times in the pores. | 162,077 |
title: Evolution in the criteria that underlie the design of a monolithic preamplifier system for microstrip detectors; abstract: Abstract Several steps through which the design of a monolithic preamplifier system for microstrip detectors has passed, are critically analyzed. From the very initial MOSFET version, several measures were gradually taken with the purpose of reducing noise. The latest design criteria aim at realizing a preamplifier system which, besides outstanding noise performances, features also a suitable degree of radiation tolerance. | 162,078 |
title: Intense equatorial flux spots on the surface of the Earth's core; abstract: A large number of high-accuracy vector measurements of the Earth\u0027s magnetic field have recently become available from the satellite Oersted, complementing previous vector data from the satellite Magsat, which operated in 1979/80. These data can be used to infer the morphology of the magnetic field at the surface of the fluid core1, ∼2,900 km below the Earth\u0027s surface. Here I apply a new methodology to these data to calculate maps of the magnetic field at the core surface which show intense flux spots in equatorial regions. The intensity of these features is unusually large—some have intensities comparable to high-latitude flux patches near the poles, previously identified as the major component of the dynamo field2. The tendency for pairing of some of these spots to the north and south of the geographical equator suggests they might be associated with the tops of equatorially symmetric columnar structures in the fluid, or their antisymmetric equivalents. The drift of the equatorial features may represent material flow or could represent wave motion; discrimination of these two effects based on future data could provide new information on the strength of the hidden toroidal magnetic field of the Earth. | 162,079 |
title: THE W BOSON MASS MEASUREMENT USING THE COLLIDER DETECTOR AT FERMILAB; abstract: As one of the most important parameters in the Standard Model (SM), the mass of the W boson (mW) is currently the limiting factor in our ability to tighten the constraint on the mass of the Higgs boson (mH) within the SM framework. This review summarizes the world\u0027s most precise mW measurement to date using ~2.2 fb-1 data collected in collisions at with the CDF II detector at the Fermilab Tevatron Collider. This review will first describe the motivation for improving the precision of mW measurement, then present the details of this analysis, followed by the final measurement result and the future perspective. | 162,080 |
title: Hyperfine Paschen–Back regime realized in Rb nanocell; abstract: A simple and efficient scheme based on a one-dimensional nanometric-thin cell\n filled with Rb and strong permanent ring magnets allows direct observation of the\n hyperfine Paschen–Back regime on the D1 line in the\n 0.5–0.7 T magnetic field. Experimental results are perfectly consistent\n with the theory. In particular, with σ+ laser excitation, the\n slopes of the B-field dependence of frequency shifts for all 10 individual\n transitions of 85,87Rb are the same and equal to 18.6 MHz/mT.\n Possible applications for magnetometry with submicron spatial resolution and tunable\n atomic frequency references are discussed. | 162,081 |
title: Magnetic properties of nanocrystalline La1−xMnO3+δ manganites: size effects; abstract: The magnetic properties of nanocrystalline manganites La1?xMnO3+? with particle size of 20 (LMO20), 25 (LMO25), and 30 nm (LMO30), prepared by the citrate method, have been investigated in the temperature range 5?320?K, magnetic field up to 90?kOe and under quasi-hydrostatic pressures up to 14.5?kbar. The studies involve sequential zero-field-cooled magnetization (M) measurements followed by magnetization measurements during cooling in the same magnetic field (H) and complementary measurements of ac susceptibility. Additional measurements of M versus H were carried out at ambient and applied pressures. All nanoparticles exhibit a paramagnetic to ferromagnetic transition (PFT) at a Curie temperature TC\u003e200?K. It was found that the relative volume of the ferromagnetic phase increases for larger particle size and approaches a value of about 93% for LMO30. The real part of the ac susceptibility of sample LMO20 exhibits strong frequency dependence in a wide temperature range below TC, whereas for sample LMO30 only relatively weak frequency dependence was observed. The magnetization of sample LMO30 exhibits a PFT of second order; the type of transition could not be established for the smaller particles. It was found that an applied pressure enhances the TC of La1?xMnO3+? nanoparticles with a pressure coefficient of dTC/dP?1.9?K?kbar?1 for LMO20 and dTC/dP?1.4?K?kbar?1 for LMO25 and LMO30 samples. Peculiar magnetic memory effects observed for sample LMO20 are discussed. | 162,082 |
title: Magnetoresistance of lanthanum manganites with activation-type conductivity; abstract: The temperature dependence of the resistivity and magnetic moment of La0.85Ba0.15MnO3 and La0.85Sr0.15MnO3 manganite single crystals in magnetic fields up to 90 kOe is investigated. Analysis of the experimental results shows that the magnetoresistance of lanthanum manganites far from the Curie temperature TC can be described quantitatively by the s-d model normally used for ferromagnets and taking into account only the exchange interaction between the spins of charge carriers and magnetic moments. These data also show that the features of lanthanum manganites responsible for colossal magnetoresistance (CMR) are manifested in a narrow temperature interval δT ≈ 20 K near TC. Our results suggest a CMR mechanism analogous to the mechanism of giant magnetoresistance (GMR) observed in Fe/Cr-type multilayers with nanometer layer thickness. The nanostratification observed in lanthanum manganites and required for GMR can be described taking into account the spread in TC in the CMR range δT. | 162,083 |
title: Magnetoresistance of mechanically induced grain boundaries in La0.7Ca0.3MnO3 films; abstract: The magnetoresistance of mechanically induced grain boundaries in La0.7Ca0.3MnO3 thin films is investigated. The grain boundaries are fabricated by a mechanical deformation of the LaAlO3 substrate prior to film deposition. During film deposition, the deformed substrate region induces some growth disorder in the film leading to a wide grain boundary. The resulting structures show a reproducible, substantial magnetoresistance in magnetic fields below 2 kG. We discuss the temperature and direction dependence of the magnetoresistance and argue that two contributions due to spin-polarized electron tunneling and the suppression of magnetic frustration by a magnetic field can be identified. | 162,084 |
title: Entropy generation for microscale forced convection: effects of different thermal boundary conditions, velocity slip, temperature jump, viscous dissipation, and duct geometry; abstract: This work presents closed form solutions for fully developed temperature distribution and entropy generation due to forced convection in microelectromechanical systems (MEMS) in the Slip-flow regime, for which the Knudsen number lies within the range 0.001\u003cKn\u003c0.1. Two different cross-sections are analyzed, being microducts (composed of two parallel plates) and micropipes, with the effects of viscous dissipation being included. Invoking the temperature jump equation, two different thermal boundary conditions are investigated, being isothermal and isoflux walls. Expressions are presented for the local and bulk temperature profiles, the Nusselt number, the Bejan number, and the entropy generation rate in terms of the key parameters. Though the results are obtained for the microscale problems, they can be generalized to the macroscale counterparts by letting Kn=0. | 162,085 |
title: EFFECTS OF COMBINED TEMPERATURE- AND DEPTH-DEPENDENT VISCOSITY AND HALL CURRENT ON AN UNSTEADY MHD LAMINAR CONVECTIVE FLOW DUE TO A ROTATING DISK; abstract: The present study investigates the effects of mixed temperature- and depth-dependent viscosity and Hall current on an unsteady flow of an incompressible electrically conducting fluid on a rotating disk in the presence of a uniform magnetic field. We assume that the fluid viscosity strongly depends on temperature and depth, which may be directly applicable to the earth\u0027s mantle and a uniform mid-ocean ridge basalt reservoir in whole mantle flow. The system of axial symmetric nonlinear partial differential equations governing the unsteady flow and heat transfer is written in cylindrical polar coordinates and reduced to nonlinear ordinary differential equations by introducing suitable similarity parameters. Solutions for the flow and temperature fields are obtained numerically assuming large Prandtl number by using Runge-Kutta and shooting methods. The nature of radial, tangential, and axial velocities and temperature in the presence of a uniform magnetic field is presented for changing various nondimensiona... | 162,086 |
title: Hyperbolic heat conduction, effective temperature, and third law for nonequilibrium systems with heat flux.; abstract: Some analogies between different nonequilibrium heat conduction models, particularly random walk, the discrete variable model, and the Boltzmann transport equation with the single relaxation time approximation, have been discussed. We show that, under an assumption of a finite value of the heat carrier velocity, these models lead to the hyperbolic heat conduction equation and the modified Fourier law with relaxation term. Corresponding effective temperature and entropy have been introduced and analyzed. It has been demonstrated that the effective temperature, defined as a geometric mean of the kinetic temperatures of the heat carriers moving in opposite directions, acts as a criterion for thermalization and is a nonlinear function of the kinetic temperature and heat flux. It is shown that, under highly nonequilibrium conditions when the heat flux tends to its maximum possible value, the effective temperature, heat capacity, and local entropy go to zero even at a nonzero equilibrium temperature. This provides a possible generalization of the third law to nonequilibrium situations. Analogies and differences between the proposed effective temperature and some other definitions of a temperature in nonequilibrium state, particularly for active systems, disordered semiconductors under electric field, and adiabatic gas flow, have been shown and discussed. Illustrative examples of the behavior of the effective temperature and entropy during nonequilibrium heat conduction in a monatomic gas and a strong shockwave have been analyzed. | 162,087 |
title: Textured ferroelectric SbNbO4 thin films deposited by ion-beam sputtering; abstract: Abstract In this letter, we report on the first synthesis of oriented SbNbO4 ferroelectric thin films on Pt coated silicon substrates. Textured SbNbO4 thin films are formed by rapid thermal annealing of films deposited by Ar+ ion-beam sputtering at room temperature. The films are characterized by X-ray diffraction spectra. Ferroelectric P-E loops are measured and dielectric properties are studied at low frequency. The effect of Pt electrodes on the formation of ferroelectric SbNbO4 thin films is discussed. | 162,088 |
title: Shape of the coherent-population-trapping resonances and high-rank polarization moments; abstract: The shape of the coherent-population-trapping (CPT) resonances was investigated theoretically and experimentally at different laser powers. The CPT resonances were observed in fluorescence on the degenerate two-level system of the $({F}_{\\ensuremath{\\varphi}}=2\\ensuremath{\\rightarrow}{F}_{f}=1)$ transition of the $^{87}\\mathrm{Rb}$ ${D}_{1}$ line by means of a Hanle effect configuration in an uncoated vacuum cell. Numerical simulations based on the density matrix formalism, which take into account the high-rank polarization moment (HRPMs) influence and the velocity distribution of the atoms, were used to calculate the shape of the nonlinear magnetic resonances. The comparison of the theoretical and experimental shapes of the CPT resonances demonstrated that the HRPMs influence the shape at all laser excitation powers, and this influence can be used to explain some peculiarities at the center of the CPT resonance shape. | 162,089 |
title: The effect of thermal boundary conditions and density stratification on the appearance of convection in the atmospheres of planets and stellar envelopes; abstract: In the present article a study is made of the effect of density stratification and thermal boundary conditions which are a consequence of the parametrization of the small-scale turbulent convection in the spherical layers of a compressible gas on the emergence of large-scale convection. | 162,090 |
title: Observing complete gravitational wave signals from dynamical capture binaries; abstract: We assess the detectability of the gravitational wave signals from highly eccentric compact binaries. We use a simple model for the inspiral, merger, and ringdown of these systems. The model is based on mapping the binary to an effective single black hole system described by a Kerr metric, thereby including certain relativistic effects such as zoom-whirl-type behavior. The resultant geodesics source quadrupolar radiation and, in turn, are evolved under its dissipative effects. At the light ring, we attach a merger model that was previously developed for quasicircular mergers but also performs well for eccentric mergers with little modification. We apply this model to determine the detectability of these sources for initial, Enhanced, and Advanced LIGO across the parameter space of nonspinning close capture compact binaries. We conclude that, should these systems exist in nature, the vast majority will be missed by conventional burst searches or by quasicircular waveform templates in the advanced detector era. Other methods, such as eccentric templates or, more practically, a stacked excess power search, must be developed to avoid losing these sources. These systems would also have been missed frequently in the initial LIGO data analysis. Thus, previous null coincidence results with detected gamma-ray bursts cannot exclude the possibility of coincident gravitational wave signals from eccentric binaries. | 162,091 |
title: Investigating the reasons of variability in Si IV and C IV broad absorption line troughs of quasars; abstract: In this paper we analyze the C IV and Si IV broad absorption troughs of two BALQSOs (J101056.69+355833.3, J114548.38+393746.6) to the individual components they consist of. By analyzing a BAL trough to its components we have the advantage to study the variations of the individual absorbing systems in the line of sight and not just the variations of the whole absorption trough or the variations of selected portions of BAL troughs exhibiting changes. We find that the velocity shifts and FWHMs (Full Width at Half Maximum) of the individual components do not vary between an interval of six years. All variable components show changes in the optical depths at line centers which are manifested as variations in the EW (Equivalent Width) of the components. In both BALQSOs, over corresponding velocities, Si IV has higher incidence of variability than C IV. From our analysis, evidence is in favour of different covering fractions between C IV and Si IV. Finally, although most of our results favour the crossing cloud scenario as the cause of variability, there is also strong piece of evidence indicating changing ionization as the source of variability. Thus, a mixed situation where both physical mechanisms contribute to BAL variability is the most possible scenario. | 162,092 |
title: $pγ$ interactions in Galactic jets as a plausible origin of the positron excess; abstract: The positron flux measured near Earth shows a rise with energy beyond 30 GeV. We show that this rise may be compatible with the production of positrons in $p \\gamma$ interactions in the jets of microquasars. | 162,093 |
title: HST/WFPC2 observations of the LMC pulsar PSR B0540–69; abstract: Context. The study of the younger, and brighter, pulsars is important for understanding the optical emission properties of isolated neutron stars through observations which, even in the 10 m-class telescope era, are much more challenging for older and fainter objects. PSR B0540−69, the second brightest (V ∼ 22) optical pulsar, is obviously a primary target for these investigations. Aims. The aims of this work are several: (i) constraining the pulsar proper motion and its velocity on the plane of the sky and improving the determination of the pulsar coordinates through optical astrometry; (ii) obtaining a more precise characterisation of the pulsar optical spectral energy distribution (SED) through a consistent set of multi-band, high-resolution, imaging photometry observations and studying the relation with the X-ray spectrum, including the presence of a spectral turnover between the two bands. Last, we aim at (iii) measuring the pulsar optical phase-averaged linear polarisation, for which only a preliminary and uncertain measurement has been obtained so far from ground-based observations, and at testing the predictions of different neutron star magnetosphere models. Methods. We performed high-resolution observations of PSR B0540−69 with the Wide Field and Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope (HST), in both direct imaging and polarimetry modes. Results. From multi-epoch astrometry we set a 3σ upper limit of 1 mas yr −1 on the pulsar proper motion, implying a transverse velocity \u003c250 km s −1 at the 50 kpc LMC distance. Moreover, we determined the pulsar absolute position with an unprecedented accuracy of 70 mas. From multi-band photometry we characterised the pulsar power-law spectrum and derived the most accurate measurement of the spectral index (αO = 0.70 ± 0.07), which indicates a spectral turnover between the optical and X-ray bands. Finally, from polarimetry we obtained a new measurement of the pulsar phase-averaged polarisation degree (PD = 16% ± 4%), consistent with magnetosphere models, depending on the actual intrinsic polarisation degree and depolarisation factor, and we found that the polarisation vector (22 ◦ ± 12 ◦ position angle) is possibly aligned with the semi-major axis of the pulsar-wind nebula and with the apparent proper motion direction of its bright emission knot. Conclusions. Deeper studies with the HST can only be possible with the refurbished Advanced Camera for Surveys (ACS) and with the new Wide Field Camera 3 (WFC3). | 162,094 |
title: Production of astatine and radon isotopes by photospallation of 232Th and 238U; abstract: Abstract Photospallation cross sections of 232 Th with bremsstrahlung beams of 0.25, 0.30 and 0.35 GeV maximum energies have been determined for 209 At (66, 87 and 280 μb), 210 At (74, 98 and 230 μb) and 121 Rn (28, 40 and 130 μb). These yields are an order of magnitude lower than predicted by the Rudstam CDMD formula, possibly as a consequence of the rather thick Cu converter that was used. Irradiation of UO 2 at 0.3 GeV resulted in cross sections for 209 At: 15.8 μb and for 210 At: 17.9 μb. Cumulative photofission cross sections have been determined for A = 135 at 0.25 GeV (1.96 mb) and at 0.35 GeV (2.53 mb). Half-lives were measured for 207 Po (6.7 h) and 211 Rn (14.6 h). | 162,095 |
title: Patterns of convection in rotating spherical shells; abstract: Patterns of convection in internally heated, self-gravitating rotating spherical fluid shells are investigated through numerical simulations. While turbulent states are of primary interest in planetary and stellar applications the present paper emphasizes more regular dynamical features at Rayleigh numbers not far above threshold which are similar to those which might be observed in laboratory or space experiments. Amplitude vacillations and spatial modulations of convection columns are common features at moderate and large Prandtl numbers. In the low Prandtl number regime equatorially attached convection evolves differently with increasing Rayleigh number and exhibits an early transition into a chaotic state. Relationships of the dynamical features to coherent structures in fully turbulent convection states are emphasized. | 162,096 |
title: Noncommutative field theories and gravity; abstract: Abstract We show that after the Seiberg–Witten map is performed the action for noncommutative field theories can be regarded as a coupling to a field dependent gravitational background. This gravitational background depends only on the gauge field. Charged and uncharged fields couple to different backgrounds and we find that uncharged fields couple more strongly than the charged ones. We also show that the background is that of a gravitational plane wave. A massless particle in this background has a velocity which differs from the velocity of light and we find that the deviation is larger in the uncharged case. This shows that noncommutative field theories can be seen as ordinary theories in a gravitational background produced by the gauge field with a charge dependent gravitational coupling. | 162,097 |
title: X-ray magnetic circular dichroism at the rare earth L2,3 edges in R2Fe14B intermetallics; abstract: We present a systematic x-ray magnetic circular dichroism (XMCD) study performed at the rare-earth (R) L2,3 edges on the R2Fe14B series. The identification of multipolar contributions to the signal allows the application of sum rules to the obtained XMCD spectra. The results show that both orbital and spinorial components of the R(5d) magnetic moment are proportional to the 4f ones. Hence, the magnetic moment of 5d shell derived from a sum-rules analysis evidences an important nonquenched orbital contribution. This result is in contradiction with Campbell’s model for R–Fe intermetallic compounds. Consequently, both XMCD sum rules and Campbell’s model have to be revised in the atomic level. | 162,098 |
title: Derivation of the heat capacity anomaly at?a first-order transition by using a semi-adiabatic relaxation technique; abstract: This paper deals with the problem of determining the heat capacity anomaly associated with a first-order transition when using relaxation calorimetry. A method of data recording and analysis is proposed, which is shown to be well suited to investigate such a feature, including its hysteretical character. This technique is applied to spinel vanadates, allowing us to shed light on a recent controversy about the double-transition which takes place in these oxides. | 162,099 |
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