Miracle-dz/UniFAR-FTUs huggingface dataset:
Differential reflectance spectroscopy of GaAlAs thin films and GaAs bulk under externally applied temperature gradient

Using vibrating optical beam, differential reflectance (DR) spectra have been obtained on GaAlAs thin films and GaAs bulk subjected to an externally applied temperature gradient. The DR spectra reveal all the critical points, namely, E0 and E0+Δ0 in GaAlAs and E0, E0+Δ0 and E1 in GaAs in the given energy range under study whereas, without the temperature gradient, DR spectra measured on homogeneous materials are structureless. The DR technique shows better sensitivity than photoreflectance on thin epilayers. Our investigation suggests that, combined with the application of a field gradient, DR can be made extremely useful for the characterization of semiconductors.
Extracting JSON Schemas with tagged unions

With data lakes and schema-free NoSQL document stores, extracting a descriptive schema from JSON data collections is an acute challenge. In this paper, we target the discovery of tagged unions, a JSON Schema design pattern where the value of one property of an object (the tag) conditionally implies subschemas for sibling properties. We formalize these implications as conditional functional dependencies and capture them using the JSON Schema operators if-then-else. We further motivate our heuristics to avoid overfitting. Experiments with our prototype implementation are promising, and show that this form of tagged unions can successfully be detected in real-world GeoJSON and TopoJSON datasets. In discussing future work, we outline how our approach can be extended further.
Behaviors of Variational and Nudging Assimilation Techniques with a Chaotic Low-Order Model

Abstract Variational and nudging data-assimilation schemes are examined within the framework of a model initialization problem using the Lorenz three-component model of Rayleigh–Benard convection. Since the intent of this study is to explore what factors influence the abilities of the two assimilation techniques to produce accurate initial conditions, identical twin experiments are conducted for various lengths of the data-assimilation window when the flow is both study state and chaotic. These experiments illustrate that the location of the model solution in phase space is an important consideration when applying either data-assimilation scheme. Decision points, when the model “chooses” which stationary point to orbit, are found to affect the ability of the assimilation techniques to find an accurate initial condition. For chaotic flow, variational assimilation produces a better initial condition when the assimilation window is short, while nudging produces a better initial condition when the assimilatio.
Gravitational Collapse in an Expanding Universe: Asymptotic Self-similar Solutions

The collapse and virialization of self-similar spherical density perturbations to a flat Einstein-de Sitter universe is investigated and in particular the asymptotic similarity solutions. Previous calculations of Gunn and Fillmore & Goldreich of the asymptotic solutions are improved here and the collapse factor of a given spherical shell is calculated. Within the framework of the asymptotic behavior exact analytical solutions are obtained
Resonance-antiresonance electromagnetic behavior in a disordered dielectric composite

In the present study, a kind of SiCw/wax composite was prepared and its electromagnetic properties were studied experimentally. It is found that Mie resonance can occur in this composite in spite of its disordered structure. The Mie resonance is believed to lead to the resonant-antiresonant electromagnetic behavior accompanied by a negative e″ in the SiCw/wax composite in the 2–18GHz band range. The resulted magnetic behavior in the current composite is believed to be weakened by the random orientation of the whiskers.
The base-scale entropy analysis of short-term heart rate variability signal

The complexity of heart rate variability (HRV) signal can reflect physiological functions and healthy status of heart system. Detecting complexity of the short-term HRV signal has an important practical meaning. We introduce the base-scale entropy method to analyze the complexity of time series. The advantages of our method are its simplicity, extremely fast calculation for very short data and anti-noise characteristic. For the well-known chaotic dynamical system—logistic map, it is shown that our complexity behaves similarly to Lyapunov exponents, and is especially effective in the presence of random Gaussian noise. This paper addresses the use of base-scale entropy method to 3 low-dimensional nonlinear deterministic systems. At last, we apply this idea to short-term HRV signal, and the result shows the method could robustly identify patterns generated from healthy and pathologic states, as well as aging. The base-scale entropy can provide convenience in practically applications.
Factor analysis of multiple batteries by maximum likelihood

McDonald's (1970) generalization of Tucker's (1958) inter-battery factor analysis model to multiple batteries is considered. The identification of parameters is examined and an iterative algorithm for obtaining maximum-likelihood estimates is provided. Consideration of the relationship between inter-battery factor analysis and canonical correlation analysis in the case of two batteries suggests a generalization of canonical coefficients to the situation where there are several batteries. Examples of the application of the procedure are given.
Low States in Cataclysmic Variables

Cataclysmic variables are usually classified into dwarf novae, nova-likes, Z Camelopardalis stars, VY Sculptoris stars, and so on, on the basis of their long-term photometric behavior. We show that some aspects of this behavior may be caused by variations in the mass transfer rate from the secondary star about the current secular mean, and the consequent stability or instability of the accretion disk, if present. The most likely cause of the mass transfer variations on these timescales (years or less) is starspots. Mass transfer variations can cause low states in systems with otherwise steady disks, but they produce only subtle effects on dwarf novae, including variations in the outburst shapes and the standstills of Z Cam systems.
A Reliability Distribution With Increasing, Decreasing, Constant and Bathtub-Shaped Failure Rates

A distribution with one scale and two shape parameters is studied. The distribution can describe increasing (I), decreasing (D), constant and bathtub-shaped (B) failure rates. This motivates the working name, IDB distribution. The IDB distribution is motivated by mixtures of a set of IFR distributions but can also be given a competing risk interpretation. For mixed distributions a more general result on the initial slope of the failure rate is given. Asymptotic results for the ML estimation of survival probabilities are given, and when possible compared with ML estimation based on the Weibull, Rayleigh and exponential distributions. Also, the asymptotic gain from classifying failures into two categories is illustrated. One application to real data is given.
Geometry of the Batalin–Fradkin–Vilkovisky theorem

We describe gauge fixing at the level of virtual paths in the path integral as a nonsymplectic BRST-type of flow on the path phase space. As a consequence, a gauge-fixed, nonlocal symplectic structure arises. Restoring of locality is discussed. A pertinent anti-Lie-bracket and an infinite dimensional group of gauge fermions are introduced. Generalizations to Sp(2)-symmetric BLT theories are made.
Stability Results for Discrete-Time Linear Systems with Markovian Jumping Parameters

Stability results for discrete-time linear systems subject to random jumps in the parameters are obtained. First, necessary and sufficient conditions for mean square stability (MSS), including the case in which the system is driven by an independent wide-sense stationary random sequence, are derived. It is shown that MSS is equivalent to the spectral radius of an augmented matrix being less than one or to the existence of a solution of a certain Lyapunov equation. In addition it is shown that the Lyapunov equation can be derived in four equivalent forms and, as a by-product, each one gives risc to an easier-to-check sufficient condition. These results give, inter alia, a unified and rather complete picture for MSS of Markovian jump linear systems. Next we derive sufficient conditions for almost sure stability of the noiseless ease. Finally, we conclude by presenting an illustrative application to adaptive filtering where a mild condition for almost sure convergence is provided.
Snow versus Rain: Looking beyond the “Magic” Numbers

Abstract Compelling evidence suggests that various lower-tropospheric thickness calculations (e.g., 1000–850- and 850–700-mb thickness) should be considered a vital element of wintertime precipitation-type forecasts. The traditional 1000–500-mb thickness often does not adequately resolve lower-tropospheric temperature profiles, which are so critical in the determination of precipitation types. During a three-winter period (1989–92) for Pittsburgh, Pennsylvania, and Albany, New York, rain events were observed with 1000–500-mb thickness values as low as 5220 m and 850-mb temperatures as low as −7°C, both values of which are well below critical-thickness thresholds, traditionally used to delineate frozen versus liquid precipitation events. One particular parameter, the 850–700-mb thickness, was occasionally more valuable as a predictor than the 1000–500-mb thickness. Snow rarely occurred with a 850–700-mb thickness > 1550 m. This study uses surface and radiosonde data to generate an array of layer-thickness .
Electronic Structure of Impurities in Ferromagnetic Iron. II. 3d and 4d Impurities

The local magnetic moment M loc , the hyperfine field H hf and the nuclear spin-lattice relaxation time T 1 of 3 d and 4 d transition metal impurities in Fe are calculated in the framework of the Green function method and in the local spin density approximation (LSD). The calculation reproduces the observed major trends of M loc , H hf and T 1 quite well, though the calculated H hf shows a systematic deviation from the experimental values in the case of impurities whose magnetic moment couples parallel to the bulk magnetization. The mechanisms of the variation of these quantities are elucidated in the light of the present ab initio calculation.
Measurements of the frequency dependence of normal modes

An experiment using a vertical array to detect acoustic normal modes in shallow water is described. A high signal‐to‐noise ratio was achieved by the use of pseudorandom pulse sequences to modulate the projector. Wide bandwidth signals and a tunable acoustic source enabled the frequency dependence of normal modes to be measured and results are in good agreement with the theory. An improved method of extracting the signal present in a single mode is described and used to examine pulse shapes and frequency spectra of individual modes.
Growing highly synchronizable scale-free networks

In this letter, a model for growing highly synchronizable networks is introduced. The model is based on preferential attachment in which the new nodes tip to old ones in a way to maximize the synchronization properties of the network. Criteria based on the eigenvectors corresponding to the second smallest and the largest eigenvalues of the Laplacian matrix of the connection graph were used to choose the old nodes to which a new node makes connection. Numerical simulations showed that these networks have considerably lower eigenratio (the largest eigenvalue of the Laplacian divided by the second smallest one), and hence better synchronizability, as compared to standard Barabási-Albert (BA) scale-free networks. These two models were also different in their statistical properties. BA networks demonstrated larger global and local efficiency, while modularity and assortativity of highly synchronizable networks were larger. The proposed model resulted in networks with almost power-law degree distribution (except an exponential start). Furthermore, the hub nodes in these networks had much smaller degree as compared to those of BA networks.
A new data acquisition concept for digital ionosondes: Phase‐based echo recognition and real‐time parameter estimation

The problem of identifying echoes in digital ionosonde observations is discussed, starting with an off‐line simulation of the procedure long used in real time by the dynasonde. In that method, echoes are defined as amplitude‐modulus peaks from rapid (10‐μs) sampling of receiver quadrature outputs; coincidence of peak time among a small number (4–8) of repeated pulses has served well to reject impulsive noise while deciding the complex‐amplitude samples to be retained for off‐line analyses. This paper presents a new method of echo recognition dependent on all of the phase information contained in the same rapid sampling. No change is made in basic sounding function, but conversion to physical parameters is done first, for all 10‐μs samples; the consistency of these parameters in five dimensions over four or more samples defines an echo, or at least a partial “glint. ” In an example recording, the new method recognizes about 60% more echoes and glints, giving better trace continuity than the earlier method. Measurement resolution among proximate echoing regions is improved. Weighted means of the physical parameters within their defining samples yields better accuracy. Almost incidentally, these results would be available immediately in a real‐time implementation of the method.
Schrödinger equation for convex plane polygons: A tiling method for the derivation of eigenvalues and eigenfunctions

Motivated by a recently advanced conjecture on the ergodic properties of Quantum Systems, the problem of solving the Schrodinger equation for a free particle in a plane polygonal enclosure is revisited. It will be shown that two elementary lemmas suffice to give a complete characterization of the polygons for which a solution can be found in terms of a finite superposition of plane waves, without making use of advanced group‐theoretical techniques. It turns out, inter alia, that these polygons, considered as classical billiards, are all and only those which are completely integrable in the sense of Arnold’s theorem.
UNIMPROVABILITY OF ESTIMATES OF HÖLDER CONSTANTS FOR SOLUTIONS OF LINEAR ELLIPTIC EQUATIONS WITH MEASURABLE COEFFICIENTS

The author considers the validity of an estimate in the norm of the Holder spaces for the solutions of linear elliptic equations , where for all (, ). This estimate does not depend on the smoothness of the coefficients . It is known (MR 83c:35059) that such an estimate holds for sufficiently small exponents depending on and . In this paper it is proved that this dependence is essential: for every one can exhibit a constant and construct a sequence in of elliptic equations, of the indicated form with smooth coefficients, whose solutions converge uniformly in the unit ball to a function that does not belong to . Bibliography: 5 titles.
Investigation of long-range surface plasmon polaritons gratings by complex mode matching method

A long range surface plasmon polaritons Bragg grating is investigated by a complex mode matching method. A high order finite difference method is employed to find the complex eigenmodes. Benefited from the cascading and doubling algorithm, the computation effort is significantly saved for Bragg gratings with large number of periods. Numerical results are verified by previous reported experiments.
The performance of several statistical tests for seasonality in monthly data

The type I and II error rates of several statistical tests for seasonality in monthly data were investigated through a computer simulation study at two nominal significance levels, α=1% and α=5%. Three models were used for the variation: annual sinusoidal; semi—annual sinusoidal; and a curve which is constant in all but three consecutive months of the year, when it exhibits a constant increase (a “one—pulse” model). The statistical tests are compared in terms of the simulation results. These results may be applied to calculate either the sample size required to detect seasonal variation of fixed amplitude or the probability of detecting seasonal variation of variable amplitude with a fixed sample size. A numerical case study is given
High-velocity gas in the Orion infrared nebula

Sensitive observations of carbon monoxide toward the Kleinmann-Low (KL) infrared nebula in Orion have revealed the presence of low-level emission extending over a radial velocity range of at least 150 km s/sup -1/. The high-velocity emission appears to be localized to a region approximately-less-than1' in diameter centered on KL. The high-velocity gas is probably associated with pre- rather than post-mainsequence object(s). However, the intensity of line radiation at these high velocities is not easily explained with simple models of mass-outflow, gravitational collapse or rotation. (AIP)
Sequence Analysis and Optimal Matching Methods in Sociology

The authors review all known studies applying optimal matching or alignment (OM) techniques to social science sequence data. Issues of data, coding, temporality, cost setting/algorithm design, and analytic strategies are considered, and substantive findings are reviewed. The authors conclude that OM techniques have produced interesting results in a wide variety of areas, the most promising being studies of careers and of sequentially organized cultural artifacts.
Raman spectroscopy of nanocrystalline GaN synthesized by arc plasma

We report on a Raman study of nanocrystalline GaN with the wurtzite structure synthesized by arc plasma method. Resonant Raman scattering is observed using 514.5 nm (2.41 eV) laser excitation, which is near the band gap of the “yellow band” (2.2–2.3 eV). Under such near-resonant excitation, new Raman bands unexpected in an ideal wurtzite GaN crystal were found. The transverse optical modes of A1 (531 cm−1) and E1 (560 cm−1), and the nonpolar modes of E2 [567 cm−1 (high) and 143 cm−1 (low)] normally observed in bulk crystals, were recorded and were observed to be resonantly enhanced. Two new bands (680 and 344 cm−1) were assigned to the inactive optical phonon modes B1 (high) and B1 (low), respectively. A broadband centered at 710 cm−1 was attributed to surface modes of the nanocrystals, providing good agreement with the calculated result based on Frohlich theory. As a result of this study, Raman scattering of GaN nanocrystals has been characterized.
Censored linear regression for case-cohort studies

SUMMARY Right-censored data from a classical case-cohort design and a stratified case-cohort design are considered. In the classical case-cohort design the subcohort is obtained as a simple random sample of the entire cohort, whereas in the stratified design this subcohort is elected by independent Bernoulli sampling with arbitrary selection probabilities. For each design and under a linear regression model, methods for estimating the regression parameters are proposed and analysed. These methods are derived by modifying the linear ranks tests and estimating equations that arise from full-cohort data using methods that are similar to the pseudolikelihood estimating equation that has been used in relative risk regression for these models. The estimators so obtained are shown to be consistent and asymptotically normal. Variance estimation and numerical illustrations are also provided.
Consistent section-averaged equations of quasi-one-dimensional laminar flow

Section-averaged equations of motion, widely adopted for slowly varying flows in pipes, channels and thin films, are usually derived from the momentum integral on a heuristic basis, although this formulation is affected by known inconsistencies. We show that starting from the energy rather than the momentum equation makes it become consistent to first order in the slowness parameter, giving the same results that have been provided until today only by a much more laborious two-dimensional solution. The kinetic-energy equation correctly provides the pressure gradient because with a suitable normalization the first-order correction to the dissipation function is identically zero. The momentum equation then correctly provides the wall shear stress. As an example, the classical stability result for a free falling liquid film is recovered straightforwardly.
Laser Cooling below the Doppler Limit in a Magneto-Optical Trap

We have measured the spring constant, friction parameter, and temperature of the motion of caesium atoms in a magneto-optical trap. The results are very different from those predicted by models based on the scattering force, which have been used up to now. We show that the behaviour can be understood in terms of the sub-Doppler cooling mechanisms which have been observed in molasses, involving atomic motion through a polarization gradient. These mechanisms can operate in a trap because the atoms congregate in a region of low magnetic field. The lowest temperature measured was (30? 15) ? K.
ILL-Posedness and Precision in Object Field Reconstruction Problems

We suppose σ(x), called the object field, is an unknown real or complex-valued function on a set E. Our knowledge of σ is given by observation, with some (small) error, of a real or complex-valued function s(ξ) given by s(ξ)=[Bσ](ξ)=∫ E b(ξ,x)σ(x)dx, σ ε F The sets E,F are subsets of Rn, where normally n=1,2,3. It is desired to determine σ(x) as well as possible; the result of this determination is denoted σ^(x) (in ideal circumstances σ^(x)=σ(x)) and is called an estimate of σ (the word estimate may or may not have a statistical implication). An inversion problem is determined when the following are specified: (1) the kernel b(ξ,x) of the integral operator; (2) the region E on which σ(x) is defined; (3) the region F over which the observation is made; (4) the set ∑ of functions σ that are allowed. It is assumed that the situation is such that σ ε L2 (E) (the space of square-integrable functions on E) and s ε L2 (F). If ∑ is all of L2 (E), the problem is an unconstrained linear inversion; if ∑ is not all of L2 (E) (∑ may be linear or nonlinear) it is a constrained linear inversion.
Application of laser photothermal spectroscopy for standoff detection of trace explosive residues on surfaces

Laser photothermal methods of standoff detection of trace explosive residues on surfaces are considered. The analysis is restricted to the most promising methods: photoacoustic spectroscopy, deflection spectroscopy, and IR photothermal imaging of objects under resonant irradiation. Particular attention is paid to the choice of radiation sources and detectors. Comparative analysis of the existing standoff detection methods for explosive particles on the object surface is performed. Prospects of laser photothermal spectroscopy in this field are discussed.
Ultrafast optical switching in distributed feedback polymer laser

We show that polymer distributed feedback lasers can be optically controlled at high bit-rate by using an ultrashort gate pulse. We perform switching-off of the laser emission exploiting the photogeneration of charge carriers from the singlet, emitting state induced, by the gate. We study this resonant non-linear process and we show that the system can in principle work at 500GHz repetition rate. There could be the possibility for our devices to be integrated into plastic waveguides or fibers, to develop plastic, large-scale integrated, ultrafast optical logic.