Miracle-dz/UniFAR-FTUs huggingface dataset:
Learning by maximizing the information transfer through nonlinear noisy neurons and "noise breakdown

The transmission of information through a nonlinear noisy neuron has been computed with the following results. The mutual information between input and output signals is, in the large-noise limit, rigorously given by the mean-squared variance of the fluctuations of the output of the nonlinear neuron. The changes of synaptic strengths that tend to maximize the mutual information are qualitatively similar to those obtained by Hebbian learning of the nonlinear neuron
Evidence of two plastic regimes controlled by dislocation nucleation in silicon nanostructures

We performed molecular dynamics simulations of silicon nanostructures submitted to various stresses and temperatures. For a given stress orientation, a transition in the onset of silicon plasticity is revealed depending on the temperature and stress magnitude. At high temperature and low stress, partial dislocation loops are nucleated in the {111} glide set planes. But at low temperature and very high stress, perfect dislocation loops are formed in the other set of {111} planes called shuffle. This result confirmed by three different classical potentials suggests that plasticity in silicon nanostructures could be controlled by dislocation nucleation.
Overcoming biases of precipitation measurement : a history of the USSR experience

Abstract Documenting the instrumentally observed precipitation climate record presents many challenges because scientists must rely on data from stations that undergo many changes in the course of their operation. Detecting changes from such networks is essential for adequate understanding of climate and global change. As an illustrative example, we review the history of the instrumentally observed precipitation in the USSR. In the USSR, similar to other countries, numerous problems must be addressed before reliable estimates of precipitation can be made. The types of problems range from inadequate and changing exposures of raingages to varying sampling periods used to measure precipitation. Using information about measurement procedures, instrument intercomparisons, and field studies, various methods have been devised to overcome biases in the measurements.
The Variability of the Solar Coronal Helium Abundance: Polar Coronal Holes Compared to the Quiet Sun

We report on measurements of the abundance ratio He/H in solar polar coronal holes and neighboring quiet coronal regions, using the SUMER spectrometer on board SOHO. In coronal holes we find He abundances smaller than or equal to the value found in the fast solar wind, 5% by number relative to H, suggesting that the flow speed of He up into the wind is equal to or greater than the flow speed for H in the regions we observe. Going to regions above quiet solar corona, we find similar He abundances at altitudes of 50'' or more, with some indication that the He abundance is increased toward its photospheric value of 8.5% relative to H lower down. We take this to indicate that the He abundance in open-field regions of the corona is never higher than 5% (as observed in the solar wind), but that in low-lying, closed magnetic field regions higher abundances may result.
The Origin of a Severe Thunderstorm in Kansas on 10 May 1985

Abstract This study of the Oklahoma–Kansas area on 10 May 1985 undertakes to explain why severe convection developed in only a small portion of northwestern Kansas despite large potential instability for surface air over the entire region and despite the approach of a mobile upper-level trough from the southwest. Special soundings from the O–K PRF-STORM program showed that a persistent thermodynamic lid above the warm moist surface boundary layer separated this layer from the middle and upper troposphere in which the instability could be realized and was almost completely effective in suppressing deep convection. Only one of the soundings with these characteristics showed temporary removal of this lid, and the only convective storm developed near the place and time of this removal. This coincidence points to removal as the likely, although not certain, cause. Isentropic trajectories showed that adiabatic lifting was the cause, and that this lift was part of a series of mesoscale waves with wavelengths of .
X-ray properties of the Be/X-ray systems 2S0114+650 = LSI+65 deg 010

Results are presented from experiments on the Einstein Observatory, HEAO-1 and OSO-8 on the temporal and spectral properties of 2S0114+650. In a 12 hour Einstein MPC and SSS observation two episodes of flaring occurred by an order of magnitude over about 1 hour. Variability on shorter time scales showed a preferred period of 14.9 minutes, but periodic pulsations were not seen in the HEAO-1 and OSO-8 data. There is some evidence that the spectrum is steeper when the source is quiescent at low luminosity, but no large spectral changes attended the flares. Absorption column densities were consistent with interstellar reddening of the proposed companion, the Be star LSI+65 deg 010. In the minute and hour variability and in the spectral character, 2S0114+650 is similar to other Be star-neutron star binary X-ray sources. Variations over several days in the OSO-8 data suggest orbital effects.
ON REPRESENTATIONS AND COMPACTIFICATIONS OF SYMMETRIC RIEMANNIAN SPACES

In the recent study of automorphic functions [2], [4], [7], it has become necessary to take boundaries of symmetric bounded domains (or more generally, of symmetric Riemannian spaces) into account and to consider explicitly the behavior of the functions on these boundaries. Now the notion of "boundary" presupposes naturally a "compactification" of the space. The purpose of this paper is to give a general method of compactifying symmetric Riemannian spaces by means of certain isometries of them into the space of all positive definite hermitian matrices. Let S be a symmetric Riemannian space of non-compact type, i.e., S = GIK, G being a (connected) semi-simple Lie group with finite center such that all its simple factors are non-compact and Ka maximal compact subgroup of G. Let g, f be the Lie algebras of G and K, respectively. Then for any faithful irreducible representation p of g in a (complex) vector space V of dimension n, we can take a suitable base in V such that p(zX) =p(X) for X e g, z denoting the automorphism of g defined by the symmetry of S around x0 = K; we have then the corresponding irreducible projective representation, denoted also by p, of G into PSL(n, C) such that the matrices p(k) corresponding to k e K are unitary. Then making x = gK e S correspond to the hermitian matrix p(g)p(g), we obtain an injection, denoted also by p, of S into the space ? P1 of all positive definite hermitian matrices of degree n and of determinant 1. This mapping p from S into 91 is an isometry (with respect to some invariant metrics in S and in ? E1) and satisfies the following conditions: (i ) p(S) is totally geodesic in ? Pl, (ii) p(S) is an irreducible set of matrices, (iii) p(x0) i_ n (the identity matrix of degree n). Conversely, it can be proved easily that any isometry p from S into ? n satisfying these conditions is obtained by the above method; we call such an isometry an irreducible representation of S into 9nF. Now denote by P(iCn) the (real) projective space associated with the (real) vector space Mn of all hermitian matrices of degree n. On1 being imbedded canonically in P(3Cn), p(S) can be considered as a subset of P(? n);
A frequency‐domain beamforming algorithm for wideband, coherent signal processing

Coherent detection processors for sonar (e.g., matched filters for active systems) require continuous time series as input and have conventionally been coupled to delay‐and‐sum time‐domain beamformers. As an alternative, we have extended the FFT beamforming technique to be functionally equivalent to a time‐domain beamformer. The procedure utilizes the ‘‘analytic’’ representations of the hydrophone signals as input and produces continuous beam time series as output, thereby allowing for complete flexibility in post‐beamformer processing. The method will be applicable when the array elements are uniformly spaced, and when a large fraction of the possible beams are to be computed. In such cases, the algorithm offers the following advantages relative to a conventional time‐domain beamformer: (1) elimination of the need for a high input sampling rate to achieve acceptable beam patterns—the frequency‐domain approach is insensitive to the sampling rate provided this exceeds the (bandpass) Nyquist rate; (2) reduc.
Hilbert-type numbers for Abel equations, growth and zeros of holomorphic functions

In this paper an upper estimate of the number of limit cycles of the Abel equation = v(x,t), x , t S1 is given. Here v is a polynomial in x with the higher coefficient one and periodic in t with period one. The bound depends on the degree n of the polynomial and the magnitude of its coefficients. In the second part we give an explicit upper estimate of the number of zeros of a holomorphic function in a compact subset of its domain through the growth rate of the function and some geometric constant that is expressed here by means of the Poincare metric. This improves the estimate given in Ilyashenko and Yakovenko (1996 J. Differ. Equ. 126 87-105).
Exact expression for a two‐dimensional finite‐part integral appearing during the numerical solution of crack problems in three‐dimensional elasticity

An exact expression is derived for the finite-part integral over a triangular domain S, where r denotes the distance of the points of the triangle from one of its vertices and f is a linear function of the Cartesian co-ordinates. The more general case where r denotes the distance of the points of the triangle from another constant point inside (or outside) the triangle is also studied and numerical results are presented. These integrals appear during the numerical solution of plane crack problems (under constant or variable pressure distribution) in three-dimensional elasticity. The availability of exact expressions for these integrals will increase the accuracy of the numerical results and, simultaneously, it will permit us not to use cubature formulae over triangular domains for the numerical solution of the previous class of problems.
Local structure of liquid GeTe via neutron scattering and ab initio simulations

We examine the local atomic order as well as some dynamic properties of the semiconducting liquid GeTe. We employ hot-neutron two-axis diffraction at three temperatures above the melting point and compare these results with ab initio molecular dynamics simulations. The simulations were based on interatomic forces derived from pseudopotentials constructed within density functional theory. At the melting temperature, the Peierls distortion responsible for the lower-temperature crystal phase is shown to manifest itself within the liquid structure. At higher temperatures in the liquid, increasing disorder in the Ge environment determines the eventual semiconductor-metal transition. The calculated kinematic viscosity of the liquid is found to agree with the experimental value and is shown to arise from the small diffusion coefficient of the Te atoms.
COMFORT: A Common Market Factor Non-Gaussian Returns Model

A new multivariate time series model with various attractive properties is motivated and studied. By extending the CCC model in several ways, it allows for all the primary stylized facts of financial asset returns, including volatility clustering, non-normality (excess kurtosis and asymmetry), and also dynamics in the dependency between assets over time. A fast EM-algorithm is developed for estimation. Each element of the vector return at time t is endowed with a common univariate shock, interpretable as a common market factor. This leads to the new model being a hybrid of GARCH and stochastic volatility, but without the estimation problems associated with the latter, and being applicable in the multivariate setting for potentially large numbers of assets. A feasible technique which allows for multivariate option pricing is presented, along with an empirical illustration.
Simplified spherical harmonics approximation of the time-dependent equation of radiative transfer for the forward problem in time-domain diffuse optical tomography

The equation of radiative transfer (ERT) is generally accepted as the most accurate model for light propagation in biological tissues. The ERT is notoriously expensive to solve numerically. Recently, Klose and Larsen have approximated the time-independent ERT using the simplified spherical harmonics equations ( SPN approximation). In this work, we outline how to derive the SPN approximation of the time-dependent ERT and obtain the associated integro- partial differential equations involving temporal convolution integrals. No approximation is made as regards the time variable in our derivation. To simplify the numerical solution of these equations, we introduce a "memory function". We discuss the numerical solution for N = 1 in the 2D and homogeneous case. We provide time evolution maps of the solution and compare it with the diffusion approximation of the ERT. The findings presented here straightforwardly extend to 3D inhomogeneous media and for higher values of N. These more complicated cases along with further details will be reported elsewhere.
Electrical characteristics of single and doubly connected Ni silicide nanowire grown by plasma-enhanced chemical vapor deposition

Ni silicide nanowires were grown by plasma-enhanced chemical vapor deposition at 350°C. Transmission electron microscope analysis showed that Ni silicide nanowire has a single crystalline Ni3Si2 structure. The nanowire alignment was controlled by dielectrophoretic method and two nanowires were placed onto Pt electrodes under an ac biasing of 10Vp-p at 100kHz. The electric characteristics of the nanowire were obtained from double connection and single connection of 5.07 and 10. 44kΩ, respectively. The resistivity values were obtained to be 183 and 208μΩcm, showing a uniform performance of the connection.
The multifractal behaviour of hierarchical density distributions

The observed power-law shape of the two-point correlation function for the distribution of cosmic structures, ξ(r)∞r −γ , as well as the hierarchical behaviour displayed by higher order correlation functions, argues for a self-similar fractal structure of the non-linear galaxy clustering. In this paper we investigate the multifractal structure implied by a list of non-Gaussian, hierarchical distributions already introduced in the literature. For each distribution we work out the multifractal spectrum of generalized dimensions, D q , implied by the small-scale non-linear clustering. We find that positive-order dimensions, which describe the scaling properties of the dist ribution inside the overdense regions, turn out to be D q =3-γ, independent of the details of the hierarchical model
Turbulent plane Couette flow subject to strong system rotation

System rotation is known to substantially affect the mean flow pattern as well as the turbulence structure in rotating channel flows. In a numerical study of plane Couette flow rotating slowly about an axis aligned with the mean vorticity, Bech & Andersson (1996a) found that the turbulence level was damped in the presence of anticyclonic system rotation, in spite of the occurrence of longitudinal counter-rotating roll cells. Moreover, the turbulence anisotropy was practically unaffected by the weak rotation, for which the rotation number Ro, defined as the ratio of twice the imposed angular vorticity Ω to the shear rate of the corresponding laminar flow, was ±0.01. The aim of the present paper is to explore the effects of stronger anticyclonic system rotation on directly simulated turbulent plane Couette flow. Turbulence statistics like energy, enstrophy and Taylor lengthscales, both componental and directional, were computed from the statistically steady flow fields and supplemented by structural information obtained by conditional sampling. The designation of the imposed system rotation as ‘high’ was associated with a reversal of the conventional Reynolds stress anisotropy so that the velocity fluctuations perpendicular to the wall exceeded those in the streamwise direction. It was observed that the anisotropy reversal was accompanied by an appreciable region of the mean velocity profile with slope ∼2Ω, i.e. the absolute mean vorticity tended to zero. It is particularly noteworthy that these characteristic features were shared by two fundamentally different flow regimes. First, the two-dimensional roll cell pattern already observed at Ro=0.01 became more regular and energetic at Ro=0.10 and 0.20, whereas the turbulence level was reduced by about 50%. Then, when Ro was further increased to 0.50, a disordering of the predominant roll cell pattern set in during a transient period until the flow field settled at a new statistically steady state substantially less affected by the roll cells. This was accompanied by a substantial amplification of the streamwise turbulent vorticity and an anomalous variation of the mean turbulent kinetic energy which peaked in the middle of the channel rather than near the walls. While the predominant flow structures of the non-rotating flow were longitudinal streaks, system rotation generated streamwise vortices, either ordered secondary flow or quasi-streamwise vortices. Eventually, at Ro=1.0, the turbulent fluctuations were completely suppressed and the flow field relaminarized.
Escape patterns, magnetic footprints, and homoclinic tangles due to ergodic magnetic limiters

The action of a set of ergodic magnetic limiters in tokamaks is investigated from the Hamiltonian chaotic scattering point of view. Special attention is paid to the influence of invariant sets, such as stable and unstable manifolds, as well as the strange saddle, on the formation of the chaotic layer at the plasma edge. The nonuniform escape process associated to chaotic field lines is also analyzed. It is shown that the ergodic layer produced by the limiters has not only a fractal structure, but it possesses the even more restrictive Wada property.
A polarization measurement method for the quantification of retardation in optic nerve fiber layer

The thickness measurement of the optic nerve fiber layer is one of the most important evaluations for carrying out glaucoma diagnosis. Because the optic nerve fiber layer has birefringence, the thickness can be measured by illuminating eye optics with circular polarized light and analyzing the elliptical rate of the detected polarized light reflected from the optic nerve fiber layer. In this method, the scattering light from the background and the retardation caused by the cornea disturbs the precise measurement. If the Stokes vector expressing the whole state of polarization can be detected, we can eliminate numerically the influence of the background scattering and of the retardation caused by the cornea. Because the retardation process of the eye optics can be represented by a numerical equation using the retardation matrix of each component and also the nonpolarized background scattering light, it can be calculated by using the Stokes vector. We applied a polarization analysis system that can detect the Stokes vector onto the fundus camera. The polarization analysis system is constructed with a CCD area image sensor, a linear polarizing plate, a micro phase plate array, and a circularly polarized light illumination unit. With this simply constructed system, we can calculate the retardation caused only by the optic nerve fiber layer and it can predict the thickness of the optic nerve fiber layer. We report the method and the results graphically showing the retardation of the optic nerve fiber layer without the retardation of the cornea.
Photoacoustic and ultrasound imaging to guide photothermal therapy: ex vivo study

In photothermal therapy, a localized temperature increase is achieved by using a continuous wave laser and optically tuned metal nanoparticles. However, the successful outcome of therapy depends on identifying the presence of nanoparticles in the tumor before therapy and monitoring temperature rise during the photothermal procedure. In this paper, we investigate the utility of photoacoustic and ultrasound imaging to guide photothermal therapy. Differences in the optical properties of tissue, enhanced by the presence of nanoparticles, provide a contrast for photoacoustic imaging. Thus, an uptake of nanoparticles in the tumor can be detected by monitoring a photoacoustic image over time. A temperature rise causes the photoacoustic signal amplitude to increase. In addition, a temperature change also leads to time shifts in an ultrasound signal, primarily due to the change in speed of sound. Therefore, by measuring the change in the photoacoustic signal, and differential motion of ultrasound speckle, the temperature rise during photothermal therapy can be computed. Combined imaging was performed with a tunable pulsed laser and an array-based ultrasound transducer. Experiments were carried out on ex-vivo animal tissue injected with composite and broadly absorbing gold nanoparticles. The photoacoustic imaging identified the presence of nanoparticles in tissue. In addition, a localized temperature increase, obtained during therapy, was monitored using photoacoustic and ultrasound imaging. The temperature profiles, obtained by both imaging techniques, were spatially and temporally co-registered. Therefore, the experimental results suggest that photoacoustic and ultrasound imaging can be used to guide and monitor photothermal therapy.
Dominant role of tunneling resistance in the electrical conductivity of carbon nanotube-based composites

The effect of nanotube/nanotube contact resistance on the electrical conductivity of carbon nanotube–based nanocomposites is studied. The tunneling resistance due to an insulating film of matrix material between crossing nanotubes is calculated by assuming a rectangular potential barrier in the insulating film. Monte Carlo simulations indicate that the tunneling resistance plays a dominant role in the electrical conductivity of composites, and the maximum tunneling distance is found to be about 1.8nm. Electrical conductivities of composites with inplane random distributions of carbon nanotubes follow the scaling law and the critical exponent depends on the level of contact resistance.
Isoparametric finite element approximation for a boundary flux problem

Purpose – To study and to analyze a second order finite‐element boundary‐flux approximation using isoparametric numerical integration.Design/methodology/approach – The numerical finite‐element integration is the main method used in this research. Since a domain with curved boundary is considered we apply an isoparametric approach. The lumped flux formulation is another method of approach in this paper.Findings – This research study presents a careful analysis of the combined effect of the numerical integration and isoparametric FEM on the boundary‐flux error. Some L2‐norm estimates are proved for the approximate solutions of the problem under consideration.Research limitations/implications – The authors offer a general study within the framework of the boundary‐flux approximation theory, which completes the results of published works in this scientific field of research.Practical implications – A useful application is to employ appropriate quadrature formulae without violating the precision of the boundar.