Miracle-dz/UniFAR-FTUs huggingface dataset:
Density Functional Theory Calculations of Topological Insulators

Density functional theory (DFT) is an approach to overcome the intractability of interacting quantum mechanical many-body problems: DFT recasts an interacting many-body equation into a set of self-consistent noninteracting single-particle equations, the so-called Kohn–Sham (KS) equations. This chapter gives an overview of some of the essential ideas underlying DFT and considers one example of widely used implementation of DFT, the plane-wave pseudopotential method. It focuses on two aspects indispensable for studying topological insulators (TIs): techniques for including spin–orbit interactions (SOIs) and evaluating Z2 topological invariants. The chapter demonstrates how DFT can be used for studying the bismuth chalcogenides Bi2Se3 and Bi2Te3 taken as generic examples of bulk Tls. It discusses some of their very basic properties such as bulk band structures, band dispersions, and spin textures of the topological states at the surfaces of these materials.
Dissipative Schrödinger–Poisson systems

We deal with a stationary, dissipative Schrodinger–Poisson system which allows for a current flow through an open, spatially one-dimensional quantum system determined by a dissipative Schrodinger operator. This dissipative Schrodinger operator can be regarded as a pseudo-Hamiltonian of the corresponding open quantum system. The (self-adjoint) dilation of the dissipative operator serves as a quasi-Hamiltonian of the system which is used to define physical quantities such as density and current for the open quantum system. The thus defined charge density in its dependence on the electrostatic potential is the nonlinear term in Poisson’s equation. We prove that the dissipative Schrodinger–Poisson system always admits a solution and all solutions are included in a ball the radius of which depends only on the data of the problem.
Local Spatiotemporal Coding and Sparse Representation Based Human Action Recognition

To handle with the limitation of bag-of-features (BoF) model which ignores spatial and temporal relationships of local features in human action recognition in video, a Local Spatiotemporal Coding (LSC) is proposed. Rather than the exiting methods only uses the feature appearance information for coding, LSC encodes feature appearance and spatiotemporal positions information simultaneously with vector quantization (VQ). It can directly models the spatiotemporal relationships of local features in space time volume (STV). In implement, the local features are projected into sub-space-time-volume (sub-STV), and encoded with LSC. In addition a multi-level LSC is also provided. Then a group of sub-STV descriptors obtained from videos with multi-level LSC and Avg-pooling are used for action video classification. A sparse representation based classification method is adopted to classify action videos upon these sub-STV descriptors. The experimental results on KTH, Weizmann, and UCF sports datasets show that our method achieves better performance than the previous local spatiotemporal features based human action recognition methods.
Convergence rate and Bahadur type representation of general smoothing spline M-estimates

: This work was motivated by Cox and O’Sullivan (1990) who derived the optimal convergence rates for smoothing spline estimates when the loss function is suﬃciently smooth. However, the study of statistical estimates resulting from nonsmooth criteria functions has become popular in recent years. In this paper, we will study the asymptotic properties of the smoothing spline estimates when the criteria functions are insuﬃciently smooth. Here, the smoothing spline estimate is deﬁned as an approximate solution to an M-estimating equation. We prove that if the derivative of loss function is Lipschitz, then the convergence rate and Bahadur type representation of the estimate can be derived simultaneously. For a speciﬁc class of loss functions with discontinuous derivatives, the Bahadur type representation is also presented provided that we know the convergence rate. Examples are given when Huber’s robust loss and median loss are employed.
The effect of boundary conditions and shear rate on streak formation and breakdown in turbulent channel flows

Experiments in a horizontal channel indicate that low‐speed/high‐speed streaks form in the region very close to the interface if shear is imposed on the liquid surface by the motion of a gas. They also form at the wall. Even though the boundary conditions at the wall and at the interface are different (no slip versus nearly free slip with regard to fluctuations), the main characteristics of the streaks appear similar. The spanwise spacing of the streaks when nondimensionalized using the local shear stress and kinematic viscosity is about 100 units whether the streaks are at the wall or at the liquid surface. The ejection and breakdown of the streaks also show qualitatively similar features. For example, the burst frequency appears to scale on local inner variables and the numerical values in nondimensionalized frequency units are about the same whether the bursts originate near the interface or the wall. A number of experiments have been done varying the shear rate at the interface to determine its role in streak formation and breakdown. From the present experiments it is concluded that the shear rate has the main influence on the phenomena and the effect of the boundary conditions is much less important.
The Temperature Scale and Mass Distribution of Hot DA White Dwarfs

Results are presented from a comprehensive spectroscopic survey of DA white dwarfs hotter than ~25,000 K. The observations consisted of CCD spectra with signal-to-noise ratios of ~100 in the blue, with ~5 Å resolution. The majority of the spectra covered the wavelength range of 3500-7500 Å, allowing the detection of a number of cool companions. To date, spectra have been obtained and analyzed for 174 DA stars. The spectra were analyzed using our model atmospheres, which are described in detail here, resulting in temperatures and gravities with average internal errors of 1% and 0.04 dex, respectively. Comparisons with previously published results showed that temperature determinations for Teff < 30,000 K were generally consistent at the 1% or better level, while spectroscopic gravity determinations based on the latest models were consistent at the 0.02 dex level. Wood's evolutionary sequences were used to derive masses for the observed stars with average internal errors of 0.02 M☉. The mass distribution for this hot sample peaked at 0.570 M☉, consistent with previous spectroscopic results for cooler samples. One salient feature of this hot sample is the presence of a significant number of massive DA stars with Teff < 50,000 K, many with M > 1.1 M☉. The ultramassive DA's comprise a much larger fraction of the total than was the case for cooler samples. Calculations based on white dwarf evolutionary models showed that a higher proportion of massive white dwarfs is expected to be found in samples with Teff ≳ 30,000 K as a result of differential cooling effects. Within the range Teff > 40,000 K, the EUV-selected subsample did have proportionately more massive stars than the optically selected subsample. However, a detailed comparison showed that EUV and optical surveys were equally capable of detecting relatively nearby massive white dwarfs. On the other hand, interstellar EUV absorption eliminated from the EUV sample many of the more distant stars that were detectable optically. Therefore, the apparent excess of massive DA white dwarfs in the EUV sample is largely due to a relative deficit of stars with more typical masses. Results are presented for individual stars, including a number of subdwarf identifications and reports of detections of cool companions. Properties of some of the more interesting binaries are discussed. We also report on some stars in the sample that evidently have varying He abundances. WD 0612+177 (G104-27) had been observed, at one point, to have photospheric He I; we confirm that He has remained absent since then. WD 0718-316 (RE 0720-314) is in a post-common-envelope binary and has photospheric He II, the abundance of which appears to vary by more than an order of magnitude over timescales of months.
Development and Application of Edible Coatings with Malva sylvestris L. Extract to Extend Shelf-Life of Small Loaf

Edible coatings that have a recognized ecological effect are an alternative to retard the processes of moisture evaporation and mold growth in bakery products. The aim of the present research was to study the influence of Malva sylvestris L. (mallow) flowers’ extract on the antimicrobial activity of edible coatings of three types of polysaccharides, pectin/P/, xanthan/X/ and carboxymethylcellulose/C/, as well as to analyze their effect on the freshness and microbiological status of coated small loaves during storage. It was found that the presence of a mallow extract had a positive effect on the fungicidal and yeasticidal activities of the X and C coatings. The loaves were evaluated for their physical (moisture, color), textural (firmness and crumb firming kinetics) and microbiological characteristics. The coatings (P, X and C) with mallow extract had the strongest moisture-retaining effect on the loaves’ crumb. The coatings with X and with P (with/without mallow extract) significantly slowed down the crumb firming process, and the value of the rate constant for the crumb firming (k) is the lowest for the X coating—0.1815 day−1. The smallest changes in the crust color were reported when mallow-based coatings were used. They have also been proven to have the lowest microbial load when they are stored for up to three days. This study shows that polysaccharide edible coatings with an active mallow component have significant potential to extend the shelf life of bakery products.
Secondary microwave background anisotropies induced by pancakes

A non-linear, flattened cosmic structure is modelled as an extremely oblate, homogeneous, compensated ellipsoid. An analytical formula is derived for the amplitude of the fractional secondary anisotropy (ΔT/T) induced in the cosmic microwave background by the gravitational evolution of such a structure. This formula turns out to be a simple generalization of the corresponding result calculated previously in the model of a thin collapsing compensated disc. Earlier results for ΔT/T induced by pancakes are confirmed here. The compensation scheme fails for perturbations such as the Great Wall in the CfA survey. Nevertheless, it can be used to put a reliable upper limit on the anisotropy induced by the Great Wall, (ΔT/T) GW
Bayesian Inference for Semiparametric Binary Regression

Abstract We propose a regression model for binary response data that places no structural restrictions on the link function except monotonicity and known location and scale. Predictors enter linearly. We demonstrate Bayesian inference calculations in this model. By modifying the Dirichlet process, we obtain a natural prior measure over this semiparametric model, and we use Polya sequence theory to formulate this measure in terms of a finite number of unobserved variables. We design a Markov chain Monte Carlo algorithm for posterior simulation and apply the methodology to data on radiotherapy treatments for cancer.
Material Constants of LiTaO3 Determined from Surface Acoustic Wave Velocities

The elastic and piezoelectric constants of LiTaO3 were determined from phase velocities of the surface acoustic waves (SAWs). Velocities were measured from many ripple frequencies caused by direct electrical coupling with the SAW delay-line response, and values to 5 significant digits were the result. The material constants were calculated using Newton's iterative numerical method. The differences between theoretical and experimental values were found to decrease by one.
Further experiments on the evolution of turbulent stresses and scales in uniformly sheared turbulence

Measurements of the Reynolds stresses, integral lengthscales and Taylor microscales are reported for several cases of uniformly sheared turbulent flows with shear values in a range substantially wider than those of previous measurements. It is shown that such flows demonstrate a self-preserving structure, in which the dimensionless Reynolds stress ratios and the dissipation over production ratio, ε/P, remain essentially constant. Flows with sufficiently large $k_{\rm s} = (1/\overline{U_{\rm c}}){\rm d}\overline{U_1}dx_2$ have exponentially growing stresses and ε/P ≈ 0.68; a linear relationship between the coefficient in the exponentiallaw and ks is shown to be compatible with measurements having ks > 3. The possibility of a self-preserving structure with asymptotically constant stresses and ε/P ≈ 1.0 is also compatible with measurements, corresponding to flows with small values of ks. The integral lengthscales appear to grow according to a power law with an exponent of about 0.8, independent of the mean shear, while the Taylor microscales, in general, approach constant values. Various attempts to scale the stresses and to predict their evolution are discussed and the applicability of Hasen's theory is scrutinized. Finally, an ‘exact’ expression for the pressure-strain rate covariance is derived and compared to some popular models.
Learning to Prioritize Planning Updates in Model-based Reinforcement Learning

Prioritizing the states and actions from which policy improvement is performed can improve the sample efficiency of model-based reinforcement learning systems. Although much is already known about prioritizing planning updates, more needs to be understood to operationalize these ideas in complex settings that involve non-stationary and stochastic transition dynamics, large numbers of states, and scalable function approximation architectures. Our paper presents an online meta-learning algorithm to address these needs. The algorithm finds distributions that encode priority in their probability mass. The paper evaluates the algorithm in a domain with a changing goal and with a fixed, generative transition model. Results show that prioritizing planning updates from samples of the meta-learned distribution significantly improves sample efficiency over fixed baseline distributions. Additionally, they point to a number of interesting opportunities for future research.
A fast alternating least squares method for third-order tensors based on a compression procedure

The alternating least squares (ALS) method is frequently used for the computation of the canonical polyadic decomposition (CPD) of tensors. It generally gives accurate solutions, but demands much time. A strong alternative to this is the alternating slice-wise diagonalization (ASD) method. It limits its targets only to third-order tensors, and in exchange for this restriction, it fully utilizes a compression technique based on matrix singular value decomposition and consequently achieves high efficiency. In this paper, we propose a new simple algorithm, Reduced ALS, which lies somewhere between ALS and ASD; it employs a similar compression procedure to ASD, but applies it more directly to ALS. Numerical experiments show that Reduced ALS runs as fast as ASD, avoiding instability ASD sometimes exhibits.
Stirring, stretching and transport generated by a pair of like-signed vortices

We consider a pair of like-signed, initially elliptical vortices with uniform vorticity distribution embedded in an incompressible, inviscid fluid occupying a two-dimensional, infinite domain. We characterize this finite-time, aperiodic, dynamical system in terms of its fixed points and separatrices, which divide the flow into inner core, inner recirculation, outer recirculation regions and outer flow. We numerically simulate the time evolution of the vortex pair using a contour dynamics algorithm. The rotational and co-rotational motion of the vortices perturb the separatrices, which undergo to deformations, yielding a tangle whose complexity increases as the amplitude of the perturbation increases. We analyse the dynamics of the tangle and explain the transport of fluid between different regions. We use two diagnostics to quantify stirring: stretching of the interface and the mix-norm. These two diagnostics characterize stirring in contradicting ways and present different sensitivity to the parameters considered. We find that stretching is dominated by the chaotic advection induced within the inner core and inner recirculation regions, whereas the mix-norm is dominated by the laminar transport induced within the outer recirculation regions. For pairs of vortices of small aspect ratio, stretching is piecewise linear and the mix-norm does not decrease monotonically. We show that these two effects are strongly coupled and synchronized with the rotational motion of the vortices. Since the nominal domain is unbounded, we quantify stirring on three concentric, circular domains. One domain nearly encloses the outer separatrices of the vortex pair, one is smaller and one larger than the first one. We show that the mix-norm is very sensitive to the size of the domain, while stretching is not. To quantify the sensitivity of stirring to the geometry of the initial concentration field, we consider, as an initial scalar field, two concentrations delimited by a straight-line interface of adjustable orientation. We show that the interface passing through the centroids of the vortices is the one most efficiently stretched, while the initial concentration field with an orthogonal interface is the most efficiently stirred. Finally, we investigate the effects of the angular impulse on the stirring performance of the vortex pair. Stretching is very sensitive to the angular impulse, while the mix-norm is not. We show that there is a value of the angular impulse which maximizes stretching and argue that this is due to two competing mechanisms.
A Compact Planar Negative Permittivity ZOR Antenna

In this paper, a compact planar zeroth-order resonator (ZOR) antenna based on epsilon negative (ENG) transmission line is presented. Thanks to the zeroth-order resonance with the aid of virtual ground, we accomplish this proposed antenna with the size of only 0. 053λ0 × 0. 157λ0 × 0. 0096λ0 at 3.580 GHz without destroying the overall substrate. The ZOR characteristic has been analyzed using provided Bloch and Floquet theory. The measured (simulated) bandwidth is about 15 MHz (10 MHz), and the measured (simulated) peak gain is about 2.60 dBi (2.68 dBi), respectively.
Dust at High Redshift: Infrared and Optical Polarimetry of an Ultra-Steep-Spectrum Radio Source at z = 2.572

We present four-color (R, J, H, and K) infrared and optical imaging polarimetry of the extended object associated with the high-redshift (z = 2.572) ultra-steep-spectrum radio source TX J083053.43+191315.6. This object has two optical/infrared subcomponents, OI1 and OI2, separated by about 3'' and aligned with the axis of the larger radio source. Aperture measurements of object OI2 and for the sum (OI1 + OI2) of the two objects' polarizations show that the polarization is a function of wavelength [%P(λ)], having a statistically significant (>99.73% confidence factor) minimum at ~4500 Å in the rest frame and a statistically significant rotation in the position angle of the electric vector, P.A. (λ), with wavelength, that in general is not tangential to the radio axis. The K-band light from the OI2 object is highly polarized (45% ± 11%), and the polarized emission is spatially extended (~10 kpc). The infrared K-band light from this object, which is redward of the Balmer break in the rest frame, cannot be dominated by starlight. The multicolor polarimetry excludes electron scattering models for the alignment effect in this object. The observed minimum in %P(λ) is predicted in models of dust scattering of a central anisotropic source, and the polarization of TX 0830+191 is remarkably well characterized by a model with silicate-graphite grains in a Mathis-Rumpl-Nordsieck power-law distribution with a cutoff in the minimum grain size of approximately 0.08 μm. The absence of smaller grains may be explained by their greater susceptibility to evaporation caused by the strong ultraviolet flux of the active galactic nucleus.
Influence of Particle Shape and Surface Friction Variability on Response of Rod-Shaped Particulate Media

Discrete element methods are important tools for the investigation of the mechanics of granular materials. In two dimensions, the reliability of these numerical approaches can be explored using physical tests on rod assemblies. This work highlights the importance of representing the actual distribution of rod shapes and surface friction in numerical simulations. The sensitivity of the response of hexagonally packed rods to minor changes in particle geometry and friction is investigated using a combination of laboratory tests and discrete element simulations. Laboratory test results highlight the influence of small variations in rod geometry on the global response, with the peak friction angle decreasing significantly as the standard deviation of the rod size distribution increased. Small changes in rod shape are also seen to be important. The numerical simulations indicate that the peak friction angle decreases as the standard deviation of the distribution of particle surface friction increases. This paper illustrates the way in which laboratory tests and numerical simulations can be used in a complementary manner to better understand the micromechanics of the response of granular materials.
Non-contact technique for testing antique optical instruments based on wavefront sensing

A non-contact method for analysing the image quality of old and delicate optical instruments is proposed. The technique is based on the use of a Shack–Hartmann wavefront sensor to obtain the Zernike coefficients of the wavefront at a certain plane, the application of our own software for the calculation of the point spread function (PSF) and a later convolution with the Gaussian image of the object to simulatethe image seen through the instrument. We have applied this technique to a terrestrial telescope from the beginning of the twentieth century. In order to test the quality of the method, the simulated PSFs and images are compared with the real ones. The main advantage of this method lies in the fact that the tested instruments do not suffer any harm due to dismantling or excessive manipulation required to transport it to outdoor observation areas.
An extended association rule mining strategy for gene relationship discovery from microarray data

DNA microarrays allow for measuring expression levels of a large number of genes between different experimental conditions and/or samples. Association rule mining (ARM) methods are helpful in finding associational relationships between genes. However, classical association rule mining (CARM) algorithms extract only a subset of the associations that exist among different binary states; therefore can only infer part of the relationships on gene regulations. To resolve this problem, we developed an extended association rule mining (EARM) strategy along with a new way of the association rule definition. Compared with the CARM method, our new approach extracted more frequent genesets from a public microarray data set. The EARM method discovered some biologically interesting association rules that were not detected by CARM. Therefore, EARM provides an effective tool for exploring relationships among genes.