ShantanuT01/DACTYL-Pretraining huggingface dataset:
We report the detailed study of structural micro-structuraland high magnetic field magneto transport propertiesof Bi2Se3single crystal. Bi2Se3 single crystal is grown through conventional solid-state reaction route via the self-flux method. Rietveld analysis on Powder X-ray Diffraction showed that the studied Bi2Se3 crystal is crystallized in single-phase without any impurity. The surface morphology analyzed through Scanning Electron Microscopy study which shows that as-grown single crystal exhibit layered type structure and the quantitative weight of the atomic constituents (Bi and Se) are found to be closeto the stoichiometric amount in energy-dispersive X-ray spectroscopy analysis. Low temperature (2.5K) magneto-resistance (MR) exhibited a v-type cusp around origin at lower magnetic field, which is the sign of weak anti-localization effect. Further, Bi2Se3 single crystal magneto conductivity data is fitted by well-known HLN equation in different magnetic field range of 2Tesla, 4Tesla and 6Tesla and the resultant found that the conduction mechanism of Bi2Se3 is dominated by WAL state.
The (perturbative) renormalization properties of the BF formulation of Yang-Mills gauge models are shown to be identical to those of the usual, second order formulation. This result holds in any number of spacetime dimensions and is a direct consequence of cohomological theorems established by G. Barnich, F. Brandt and the author (Commun.Math.Phys., 174 (1995) 57).
We explore the effect of a (non) magnetic impurity on the thermal transport of the spin-1/2 Heisenberg chain model. This unique system allows to probe Kondo-type phenomena in a prototype strongly correlated system. Using numerical diagonalization techniques we study the scaling of the frequency dependent thermal conductivity with system size and host-impurity coupling strength as well as the dependence on temperature. We focus in particular on the analysis of cutting-healing of weak links or a magnetic impurity by the host chain via Kondo-like screening as the temperature is lowered.
The formalism of linear response theory for Skyrme forces including tensor terms presented in article [1] is generalized for the case of a Skyrme energy density functional in infinite matter. We also present analytical results for the odd-power sum rules, with particular attention to the inverse energy weighted sum rule, $M_{-1}$, as a tool to detect instabilities in Skyrme functionals.
This paper is a preliminary report on our search for new good examples of Hall's Conjecture. We present a new algorithm that will detect all good examples within a given search space. We have implemented the algorithm, and our executions have so far found five new good examples.
Radiative shocks are shocks in a gas where the radiative energy and flux coming from the very hot post-shock material are non-negligible in the shock's total energy budget, and are often large enough to heat the material ahead of the shock. Many simulations of radiative shocks, both in the contexts of astrophysics and laboratory experiments, use a grey treatment of radiative transfer coupled to the hydrodynamics. However, the opacities of the gas show large variations as a function of frequency and this needs to be taken into account if one wishes to reproduce the relevant physics. We have performed radiation hydrodynamics simulations of radiative shocks in Ar using multigroup (frequency dependent) radiative transfer with the HERACLES code. The opacities were taken from the ODALISC database. We show the influence of the number of frequency groups used on the dynamics and morphologies of subcritical and supercritical radiative shocks in Ar gas, and in particular on the extent of the radiative precursor. We find that simulations with even a low number of groups show significant differences compared to single-group (grey) simulations, and that in order to correctly model such shocks, a minimum number of groups is required. Results appear to eventually converge as the number of groups increases above 50. We were also able to resolve in our simulations of supercritical shocks the adaptation zones which connect the cooling layer to the final post-shock state and the precursor. Inside these adaptation zones, we find that the radiative flux just ahead of the shock in one or several high-opacity groups can heat the gas to a temperature higher than the post-shock temperature. Through the use of Hugoniot curves, we have checked the consistency of our radiation hydrodynamics scheme by showing that conservation of mass, momentum and energy (including radiative flux) holds. ABRIDGED.
Heralding of single photon at 1550 nm from pump pulsed non degenerate spontaneous parametric downconversion is demonstrated. P(1) and P(2) of our source are 0.1871 and 2.4 x 10 ^-3 respectively. Triggering of our source is 2.16 x 10^5 trigger.s^-1. This source may be used in QKD system.
Opacity enhancements for stellar interior conditions have been explored to explain observed pulsation frequencies and to extend the pulsation instability region for B-type main-sequence variable stars. For these stars, the pulsations are driven in the region of the opacity bump of Fe-group elements at $\sim$200,000 K in the stellar envelope. Here we explore effects of opacity enhancements for the somewhat cooler main-sequence A-type stars, in which $p$-mode pulsations are driven instead in the second helium ionization region at $\sim$50,000 K. We compare models using the new LANL OPLIB vs. LLNL OPAL opacities for the AGSS09 solar mixture. For models of 2 solar masses and effective temperature 7600 K, opacity enhancements have only a mild effect on pulsations, shifting mode frequencies and/or slightly changing kinetic-energy growth rates. Increased opacity near the bump at 200,000 K can induce convection that may alter composition gradients created by diffusive settling and radiative levitation. Opacity increases around the hydrogen and 1st He ionization region (13,000 K) can cause additional higher-frequency $p$ modes to be excited, raising the possibility that improved treatment of these layers may result in prediction of new modes that could be tested by observations. New or wider convective zones and higher convective velocities produced by opacity increases could also affect angular momentum transport during evolution. More work needs to be done to quantify the effects of opacity on the boundaries of the pulsation instability regions for A-type stars.
We present a self-supervised human mesh recovery framework to infer human pose and shape from monocular images in the absence of any paired supervision. Recent advances have shifted the interest towards directly regressing parameters of a parametric human model by supervising them on large-scale datasets with 2D landmark annotations. This limits the generalizability of such approaches to operate on images from unlabeled wild environments. Acknowledging this we propose a novel appearance consensus driven self-supervised objective. To effectively disentangle the foreground (FG) human we rely on image pairs depicting the same person (consistent FG) in varied pose and background (BG) which are obtained from unlabeled wild videos. The proposed FG appearance consistency objective makes use of a novel, differentiable Color-recovery module to obtain vertex colors without the need for any appearance network; via efficient realization of color-picking and reflectional symmetry. We achieve state-of-the-art results on the standard model-based 3D pose estimation benchmarks at comparable supervision levels. Furthermore, the resulting colored mesh prediction opens up the usage of our framework for a variety of appearance-related tasks beyond the pose and shape estimation, thus establishing our superior generalizability.
We consider a system $x(t)=(x_{1}(t),...,x_{N}(t))$ consisting of $N$ Brownian particles with synchronizing interaction between them occurring at random time moments $\{\tau_{n}\}_{n=1}^{\infty}$. Under assumption that the free Brownian motions and the sequence $\{\tau_{n}\}_{n=1}^{\infty}$ are independent we study asymptotic properties of the system when both the dimension~$N$ and the time~$t$ go to infinity. We find three time scales $t=t(N)$ of qualitatively different behavior of the system.
We present a derivation of the time evolution equations for the energy content of nonhelical magnetic fields and the accompanying turbulent flows from first principles of incompressible magnetohydrodynamics in the general framework of homogeneous and isotropic turbulence. This is then applied to the early Universe, i.e., the evolution of primordial magnetic fields. Numerically integrating the equations, we find that most of the energy is concentrated at an integral wavenumber scale k_I where the turbulence turn over time equals the Hubble time. At larger length scales L, i.e., smaller wavenumbers q = 2 \pi / L << k_I, independent of the assumed turbulent flow power spectrum, mode-mode coupling tends to develop a small q magnetic field tail with a Batchelor spectrum proportional to the fourth inverse power of L and therefore a scaling for the magnetic field of B ~ L^(-5/2).
Reliable estimates of neutrino-nucleus reactions in the resonance-excitation region play an important role in many of the on-going and planned neutrino oscillation experiments. We study here neutrino-nucleus reactions in the delta-particle excitation region with the use of neutrino pion-production amplitudes calculated in a formalism in which the resonance contributions and the background amplitudes are treated on the same footing. Our approach leads to the neutrino-nucleus reaction cross sections that are significantly different from those obtained in the conventional approach wherein only the pure resonance amplitudes are taken into account. To assess the reliability of our formalism, we calculate the electron-nucleus scattering cross sections in the same theoretical framework; the calculated cross sections agree reasonably well with the existing data.
We present preliminary results of numerical simulations of dissipationless merging of stellar systems, aimed at exploring the consequences of merging between gas free, spheroidal systems. In particular, we study the dynamical and structural characteristics of hierarchical merging between equal mass stellar systems, and we compare the properties of the end-products with the most important structural and dynamical scaling relations obeyed by spheroids. In the explored hierarchy of four successive mergings we find that the FP tilt is marginally conserved, but both the Faber-Jackson and Kormendy relations are not conserved.
We present the effective Hamiltonian for an electron-nucleus interaction in non-relativistic limit up to the second order in the inverse nucleon mass. This Hamiltonian takes into account the distortion of electron waves and allows to calculate its effect as well as matrix elements for off-shell transitions in $(e,e'p)$ reactions.
Standard theories of electroweak interactions are based on the concept of a gauge symmetry broken by the Higgs mechanism. If they are placed in an environment with a sufficiently high temperature, the symmetry gets restored. It turns out that the characteristics of the symmetry restoring phase transition, such as its order, are important for cosmological applications, such as baryon asymmetry generation. We first briefly review how, by a combination of analytic and numerical methods, the properties of the phase transition can be systematically resolved for any given type of a (weakly interacting) Higgs sector. We then summarise the numerical results available for the Standard Model, and present a generic model independent statement as to how the Higgs sector should differ from the Standard Model for the properties of the transition to be very different. As an explicit example, we discuss the possibilities available for a strong transition in the experimentally allowed parameter region of the Minimal Supersymmetric Standard Model.
A quantum time-dependent spectrum analysis, or simply, quantum spectral analysis (QSA) is presented in this work, and it is based on Schrodinger equation, which is a partial differential equation that describes how the quantum state of a non-relativistic physical system changes with time. In classic world is named frequency in time (FIT), which is presented here in opposition and as a complement of traditional spectral analysis frequency-dependent based on Fourier theory. Besides, FIT is a metric, which assesses the impact of the flanks of a signal on its frequency spectrum, which is not taken into account by Fourier theory and even less in real time. Even more, and unlike all derived tools from Fourier Theory (i.e., continuous, discrete, fast, short-time, fractional and quantum Fourier Transform, as well as, Gabor) FIT has the following advantages: a) compact support with excellent energy output treatment, b) low computational cost, O(N) for signals and O(N2) for images, c) it does not have phase uncertainties (indeterminate phase for magnitude = 0) as Discrete and Fast Fourier Transform (DFT, FFT, respectively), d) among others. In fact, FIT constitutes one side of a triangle (which from now on is closed) and it consists of the original signal in time, spectral analysis based on Fourier Theory and FIT. Thus a toolbox is completed, which it is essential for all applications of Digital Signal Processing (DSP) and Digital Image Processing (DIP); and, even, in the latter, FIT allows edge detection (which is called flank detection in case of signals), denoising, despeckling, compression, and superresolution of still images. Such applications include signals intelligence and imagery intelligence. On the other hand, we will present other DIP tools, which are also derived from the Schrodinger equation.
In this paper, we introduce a weak maximum principle-based approach to input-to-state stability (ISS) analysis for certain nonlinear partial differential equations (PDEs) with boundary disturbances. Based on the weak maximum principle, a classical result on the maximum estimate of solutions to linear parabolic PDEs has been extended, which enables the ISS analysis for certain {}{nonlinear} parabolic PDEs with boundary disturbances. To illustrate the application of this method, we establish ISS estimates for a linear reaction-diffusion PDE and a generalized Ginzburg-Landau equation with {}{mixed} boundary disturbances. Compared to some existing methods, the scheme proposed in this paper involves less intensive computations and can be applied to the ISS analysis for a {wide} class of nonlinear PDEs with boundary disturbances.
Recent observations of Seyfert 1 AGN with Chandra, XMM-Newton and Suzaku revealed broad iron K_alpha emission lines, some relativistically blurred. For galactic black hole X-ray binaries XMM-Newton spectra during hard state also reveal the presence of a relativistic iron emission line and a thermal component, interpreted as an indication for a weak inner cool accretion disk underneath a hot corona. These thermal components were found after the transition from soft to hard spectral state and can be understood as sustained by re-condensation of gas from an advection-dominated flow (ADAF) onto the disk. In view of the similarity of accretion flows around stellar mass and supermassive black holes we discuss whether the broad iron emission lines in Seyfert 1 AGN can be understood as arising from a similar accretion flow geometry. We derive Eddington-scaled accretion rates for Seyfert galaxies with strong lines in samples of Miller (2007) and Nandra et al. (2007). For the evaluation we use the observed X-ray luminosity, bolometric corrections and black hole masses from literature, most values taken from Fabian and Vasudevan (2009). Rates derived are less than 0.1 of the Eddington rate for more than half of the sources. For 10^7 to 10^8 solar mass black holes in Seyfert 1 AGN this limit corresponds to 0.01 to 0.2 solar masses per year. Our investigation shows that for quite a number of Seyfert AGN in hard spectral state iron emission lines can arise from an inner weak disk surrounded by an ADAF as predicted by the re-condensation model. Some of the remaining sources with higher accretion rates may be in a spectral state comparable to the "very high" state of LMXBs. (abridged)
The analysis of twisted (vortex) paraxial photons and electrons is fulfilled in the framework of relativistic quantum mechanics. The use of the Foldy-Wouthuysen representation radically simplifies a description of relativistic electrons and clarifies fundamental properties of twisted particles. It is demonstrated that the twisted photon defined by the Laguerre-Gauss wave function is luminal. Its apparent subluminality takes place because the photon energy is contributed by the hidden transversal motion while the average transversal momentum vanishes. Nevertheless, the Laguerre-Gauss photon can be self-consistently modeled by a subluminal centroid with a nonzero kinematic (Lorentz-invariant) mass. An applicability of this model is a consequence of independence of centroid parameters from the longitudinal coordinate. All twisted and untwisted Laguerre-Gauss modes are subliminal. The Laguerre-Gauss electron has similar properties. The new effect of a quantization of the velocity and mass of the Laguerre-Gauss photon and electron is predicted. This effect is observable for the photon. The twisted photon and electron modeled by the centroids are considered in the general noninertial frame. Their inertial masses coinciding with kinematic ones are determined. The orbital magnetic moment of the Laguerre-Gauss electron does not depend on the radial quantum number.
LiOsO$_3$ has been recently identified as the first unambiguous "ferroelectric metal", experimentally realizing a prediction from 1965 by Anderson and Blount. In this work, we investigate the metallic state in LiOsO$_3$ by means of infrared spectroscopy supplemented by Density Functional Theory and Dynamical Mean Field Theory calculations. Our measurements and theoretical calculations clearly show that LiOsO$_3$ is a very bad metal with a small quasiparticle weight, close to a Mott-Hubbard localization transition. The agreement between experiments and theory allows us to ascribe all the relevant features in the optical conductivity to strong electron-electron correlations within the $t_{2g}$ manifold of the osmium atoms.
In this paper, we derive the mass exclusion limits for the hypothetical vector resonances of a strongly interacting extension of the Standard model using the most recent upper bounds on the cross sections for various resonance production processes. The $SU(2)_{L+R}$ triplet of the vector resonances under consideration is embedded into the effective Lagrangian based on the non-linear sigma model with the $125$-GeV $SU(2)_{L+R}$ scalar singlet. No direct interactions of the vector resonance to the SM fermions are assumed. We find that among eleven processes considered in this paper only those where the vector resonances decay to $WW$ and $WZ$ provide the mass exclusion limit. Depending on the values of other parameters of the model the mass limit can be as low as 1 TeV.
Spintronics is an approach to electronics in which the spin of the electrons is exploited to control the electric resistance R of devices. One basic building block is the spin-valve, which is formed if two ferromagnetic electrodes are separated by a thin tunneling barrier. In such devices, R depends on the orientation of the magnetisation of the electrodes. It is usually larger in the antiparallel than in the parallel configuration. The relative difference of R, the so-called magneto-resistance (MR), is then positive. Common devices, such as the giant magneto-resistance sensor used in reading heads of hard disks, are based on this phenomenon. The MR may become anomalous (negative), if the transmission probability of electrons through the device is spin or energy dependent. This offers a route to the realisation of gate-tunable MR devices, because transmission probabilities can readily be tuned in many devices with an electrical gate signal. Such devices have, however, been elusive so far. We report here on a pronounced gate-field controlled MR in devices made from carbon nanotubes with ferromagnetic contacts. Both the amplitude and the sign of the MR are tunable with the gate voltage in a predictable manner. We emphasise that this spin-field effect is not restricted to carbon nanotubes but constitutes a generic effect which can in principle be exploited in all resonant tunneling devices.
The abundance of Sodium (Na), its low-cost, and low reduction potential provide a lucrative inexpensive, safe, and environmentally benign alternative to Lithium Ion Batteries (LIBs). The significant challenges in advancing Sodium Ion Battery (NIB) technologies lies in finding the better electrode materials. Experimental investigations revealed the real potency of Germanium (Ge) as suitable anode materials for NIBs. However, a systematic atomistic study is necessary to understand the fundamental aspects of capacity-voltage correlation, microstructural changes of Ge, as well as diffusion kinetics. We, therefore, performed the Density Functional Theory (DFT) and Ab Initio Molecular Dynamics (AIMD) simulation to investigate the sodiation-desodiation kinetics in Germanium-Sodium system (Na64Ge64). We analyzed the intercalation potential and capacity correlation for intermediate equilibrium structures and compared our data with the experimental results. Effect of sodiation on inter-atomic distances within Na-Ge system is analyzed by means of Pair Correlation Function (PCF). This provides insight into possible microstructural changes taking place during sodiation of amorphous Ge (a-Ge). We further investigated the diffusivity of sodium in a-Ge electrode material and analyzed the volume expansion trend for Na64Ge64 electrode system. Our computational results provide the fundamental insight into the atomic scale and help experimentalists design Ge based NIBs for real-life applications.
In this paper, we have searched the existence of the similarity solution for plane symmetric inhomogeneous cosmological models in general relativity. The matter source consists of perfect fluid with proportionality relation between expansion scalar and shear scalar. The isovector fields of Einstein's field equation for the models under consideration are derived. A new class of exact solutions of Einstein's field equation have been obtained for inhomogeneous space-time. The physical behaviors and geometric aspects of the derived models have been discussed in detail.
We define a weighted multiplicity function for closed geodesics of given length on a finite area Riemann surface. These weighted multiplicities appear naturally in the Selberg trace formula, and in particular their mean square plays an important role in the study of statistics of the eigenvalues of the Laplacian on the surface.   In the case of the modular domain, E. Bogomolny, F. Leyvraz and C. Schmit gave a formula for the mean square, which was rigorously proved by M. Peter. In this paper we calculate the mean square of weighted multiplicities for some surfaces associated to congruence subgroups of the unit group of a rational quaternion algebra, in particular for congruence subgroups of the modular group. Remarkably, the result turns out to be a rational multiple of the mean square for the modular domain.