Miracle-dz/UniFAR-FTUs huggingface dataset:
Rolling-Sample Volatility Estimators

We propose extensions of the continuous record asymptotic analysis for rolling sample variance estimators developed for estimating the quadratic variation of asset returns, referred to as integrated or realized volatility. We treat integrated volatility as a continuous time stochastic process sampled at high frequencies and suggest rolling sample estimators which share many features with spot volatility estimators. We discuss asymptotically efficient window lengths and weighting schemes for estimators of the quadratic variation and establish links between various spot and integrated volatility estimators. Theoretical results are complemented with extensive Monte Carlo simulations and an empirical investigation.
A new planar pattern for camera calibration

In this paper, we proposed a novel method for correcting the 2D calibration target. Firstly, we captured multiple images of the inaccurate calibration target from multi-views and located the coordinates of those circle landmarks in these images. Secondly, homonymous landmarks in different images could be detected by a scheme for a special topology relation. Thirdly, we could accurately reconstruct the 3D coordinates of landmarks with a scale constraint using bundle adjustment strategy. And finally, the scale was computed from an accurate distance between any two landmarks. Then we could obtain the truly coordinates of landmarks, which multiplied by the scale. The experimental results validated that our method is efficient, high-precision, low-cost and easy-implementation, which can be widely applied in vision measurement and system calibration.
Direct observation of an optically induced charge density wave transition in 1T-TaSe2

Four-dimensional ultrafast transmission electron microscopy (4D-UTEM) measurements reveal a rich variety of structural dynamic phenomena at a phase transition in the charge-density-wave (CDW) 1T-TaSe2. Through the photoexcitation, remarkable changes on both the CDW intensity and orientation are clearly observed associated with the transformation from a commensurate (C) into an incommensurate (IC) phase in a time-scale of about 3 ps. Moreover, the transient states show up a notable "structurally isosbestic point" at a wave vector of qiso where the C and IC phases yield their diffracting efficiencies in an equally ratio. This fact demonstrates that the crystal planes parallel to qiso adopts visibly common structural features in these two CDW phases. The second-order characters observed in this nonequilibrium phase transition have been also analyzed based on the time-resolved structural data.
Lamperti Transform and a Series Decomposition of Fractional Brownian Motion

The Lamperti transformation of a self-similar process is a strictly stationary process. In particular, the fractional Brownian motion transforms to the second order stationary Gaussian process. This process is represented as a series of independent processes. The terms of this series are Ornstein-Uhlenbeck processes if $H 1/2$. From the representation effective approximations of the process are derived. The corresponding results for the fractional Brownian motion are obtained by applying the inverse Lamperti transformation. Implications for simulating the fractional Brownian motion are discussed. (Less)
Non‐axisymmetric solar magnetic fields

A simple non-linear, non-axisymmetric mean field dynamo model is applied to a differentially rotating spherical shell. Two approximations are used for the angular velocity, to represent what is now believed to be the solar rotation law. In each case, stable solutions are found which possess a small non-axisymmetric field component. Although the model has a number of obvious shortcomings, it may be relevant to the problem of the solar active longitudes.
Accumulation effect of SiO2 protective layer on multi-shot laser-induced damage in high-reflectivity HfO2/SiO2 coatings

The accumulation effects in high-reflectivity (HR) HfO2/SiO2 coatings under laser irradiation are investigated. The HR HfO2/SiO2 coatings are prepared by electron beam evaporation at 1 064 nm. The laser-induced damage threshold (LIDT) are measured at 1 064 nm and at a pulse duration of 12 ns, in 1-on-1 and S-on-1 modes. Multi-shot LIDT is lower than single-shot LIDT. The laser-induced and native defects play an important role in the multi-shot mode. A correlative theory model based on critical conduction band electron density is constructed to elucidate the experimental phenomena.
Finite-size corrections in the quantum Hall effect

The Hall conductivity of a full Landau band in a strip geometry is calculated. It is shown that finite-size corrections to the ideal value e2/h of the conductivity are at most of order ( lambda /L)2 ( lambda and L are the magnetic length and the width of the strip, respectively). The calculation has a useful by-product: it shows that the oscillations in the Hall conductivity, as a function of flux in Loughlin's theory (1981), are of the same order as the finite-size corrections. The calculation also demonstrates that in the limit L to infinity the result e2/h holds independently of the strength of the external electric field. Thus there are no field-dependent corrections to the linear response result.
The Use of Individual Effects and Residuals in Fitting Equations to Data

Componentrplus-residual plots, plots of the estimated effect of each independent variable at each observed data point plus corresponding residuals, are used as an aid (1) to choose an appropriate form of the equation, (2) to observe the distribution of the observations over the range of each independent variable and (3) to estimate the influence of each observation on each component of the equation. With the help of indicator variables and the C p search technique, far-out observations can be tested to see if their responses are compatible with those of the remainder of the data. Examples are given from studies of manufacturing and marketing data in which either a new form of the equation is found or a new insight is gained into the limitations and strengths of the fitted equation.
Monitoring the course of the HIV‐1 epidemic: The influence of patterns of fertility on HIV‐1 prevalence estimates

An age structured model of heterosexual HIV‐1 transmission is used to explore the impact of observed patterns of fertility on measures of HIV prevalence derived from child bearing women. Observed reductions in fertility caused by women being outside sexual unions before the age of 20 years, the influence of bacterial sexually transmitted infections and the influence of HIV associated morbidity are all included in the model. We illustrate how the biases in prevalence estimates for a localised epidemic can change with time since the start of the epidemic. As the average age of HIV infected women increases, the over‐estimate of prevalence from antenatal clinic samples first increases and then declines. This works in opposition to the influence of HIV‐1 on fertility, which causes HIV‐1 prevalence to be under‐estimated initially. Additionally a reduction in fertility associated with bacterial infection in the highest sexual activity classes causes a substantial under‐estimate of HIV prevalence initially, but with the greater HIV associated mortality in this population the bias reduces rapidly.
Spin Hall effect-controlled magnetization dynamics in NiMnSb

We investigate the influence of a spin current generated from a platinum layer on the ferromagnetic resonance (FMR) properties of an adjacent ferromagnetic layer composed of the halfmetallic half-Heusler material NiMnSb. Spin Hall nano-oscillator devices are fabricated, and the technique of spin torque FMR is used to locally study the magnetic properties as in-plane anisotropies and resonance fields. A change in the FMR linewidth, in accordance with the additional spin torque produced by the spin Hall effect, is present for an applied dc current. For sufficiently large currents, this should yield auto-oscillations, which however are not achievable in the present device geometry.
CLASSICAL-LIMIT GREEN'S FUNCTION (FIXED-ENERGY PROPAGATOR) AND CLASSICAL QUANTIZATION OF NONSEPARABLE SYSTEMS.

On the basis of a classical‐limit approximation for the Green's function, a classical quantum condition for general, nonseparable dynamical systems is obtained. Bound‐state eigenvalues are seen to be associated with stable periodic trajectories, and quasibound (or metastable) states are related to unstable periodic trajectories. Application is made to ns2 states of the two‐electron atom, and quite resaonable results are obtained for the energies of the 1s2 and 2s2 states of He and H−. An accurate value is also obtained for the lowest eigenvalue of three identical bosons (e.g., helium atoms) interacting through pair Morse potentials.
Scaled measurements of global space-charge induced image blur in electron beam projection system

Previous results on simulations of space-charge induced blur in electron projection systems indicated serious limitations on throughput particularly as minimum feature sizes (MFSs) are reduced below 100 nm. For example, a 40-cm-long 50 kV column might have a maximum throughput of only 0.2 cm2/s at MFS=50 nm [R. F. W. Pease et al., MNE, Italy, 1999]. Direct experimental verification is difficult, so we have developed a set of theory-based scaling laws for electron optics and have carried out a series of experiments for verifying these laws. Our experimental results support the earlier predictions and also confirmed that shortening the column length to the minimum allowed by the maximum practical focusing field strengths (e.g., 1 T and 107 V/m) should bring about dramatic (20- to 50-fold) improvements.
On “A Consistent Theory for Linear Waves of the Shallow-Water Equations on a Rotating Plane in Midlatitudes”

Abstract Recently, Paldor et al. provided a consistent and unified theory for Kelvin, Poincare (inertial–gravity), and Rossby waves in the rotating shallow-water equations (SWE). Unfortunately, the article has some errors, and the effort is made to correct them in this note. Also, the eigenvalue problem is rewritten in a dimensional form and then nondimensionalized in terms of more traditional nondimensional parameters and compared to the dispersion relations of the old and new theories. The errors in Paldor et al. are only quantitative in nature and do not alter their major results: Rossby waves can have larger phase speeds than what is predicted from the classical theory, and Rossby and Poincare waves can be trapped near the equatorward boundary.
Optical and X-Ray Properties of Cooling Neutron Stars

Blackbody fits to the soft X-ray spectra of cooling neutron stars will, in general, overestimate the surface temperature of the source. We examine blackbody fits to the spectra predicted by light-element neutron star model atmospheres folded with the ACIS response matrices and quantify the inferred temperature error for a range of magnetic field strengths representative of the broad populations of isolated cooling neutron stars. Results for the Position Sensitive Proportional Counter are derived for comparative purposes. In each example, the blackbody temperature systematically overestimates the underlying flux temperature of the model and is an unreliable gauge by which to estimate the surface properties of neutron stars. We demonstrate a linear relationship between flux temperature and peak energy, similar to Wien displacement, as a function of magnetic field strength for the model atmospheres. We calculate the excess optical magnitude predicted from the model atmospheres with respect to the Rayleigh-Jeans portion of the fitted blackbody. We detail the nature and magnitude of these discrepancies and identify their origin in the opacity of the atmospheric plasma, the magnitude of interstellar absorption, and the instrumental response function.
The partition function of a topological field theory

This is the sequel to my paper ‘TCFTs and Calabi–Yau categories’, Advances in Mathematics 210 (2007) no. 1, 165–214. Here we extend the results of that paper to construct, for certain Calabi–Yau A∞ categories, something playing the role of the Gromov–Witten potential. This is a state in the Fock space associated to periodic cyclic homology, which is a symplectic vector space. Applying this to a suitable A∞ version of the derived category of sheaves on a Calabi–Yau yields the B model potential, at all genera. The construction does not go via the Deligne–Mumford spaces, but instead uses the Batalin–Vilkovisky algebra constructed from the uncompactified moduli spaces of curves by Sen and Zwiebach. The fundamental class of Deligne–Mumford space is replaced here by a certain solution to the quantum master equation, essentially the ‘string vertices’ of Zwiebach. On the field theory side, the BV operator has an interpretation as the quantized differential on the Fock space for periodic cyclic chains. Passing to homology, something satisfying the master equation yields an element of the Fock space.
Speech understanding in babble noise and syllabic-range temporal processing in aging

The ability to understand speech in multitalker noise was measured in a group of 46 elderly (71.6+/-6.03 years) having at worst moderate presbycusic hearing loss, using the SPIN test with the target and an 8-talker babble presented either monaurally (left or right) or, using generic HRTF spatialization, with the target at 45 degrees right or left flanked by two independent 4-talker babble on each side. The subjects' temporal processing was measured as (1) the reverberation time yielding a 15 percent decrease in word comprehension and (2) as the minimum modulation index necessary to segregate two streams generated by modulating, at an average frequency of 4.375 Hz, two carriers consisting of harmonics 4, 5, and 6 having fundamental frequencies of 107 and 189 Hz, that produced two simultaneous three-pulse envelopes, one accelerating and one decelerating. With effects of hearing loss under control, the data exhibited correlations between intelligibility in babble and temporal processing that were significant.
Distribution of density in an ion-exosphere of a nonrotating planet.

A model of an ion-exosphere is set up and an expression is derived for the variation of density with altitude. The ions are considered to be under the control of superimposed gravitational and static, centered-dipole magnetic fields and to have mirror points in the barosphere. Collisions are ignored and the particles are assumed to be trapped in the dipole field.By use of the first adiabatic invariant and Liouville's theorem, the density is found to fall off faster with height in the exomagnetosphere than in either a neutral exosphere or an ionized barosphere.
STUDY ON TOPOLOGICAL SPACES WITH THE SEMI-T ½ SEPARATION AXIOM

The present paper consists of two parts. Since the re- cent paper (4) proved that an Alexandroff T0-space is a semi-T 1 - space, the first part studies semi-open and semi-closed structures of the Khalimsky nD space. The second one focuses on the study of a relation between the LS-property of (SC n 1;l1 k1 SC n2;l2 k2 ;k) relative to the simple closed ki-curves SC n i;li ki ;i 2 f1; 2g and its normal k- adjacency. In addition, the present paper points out that the main theorems of Boxer and Karaca's paper (3) such as Theorems 4.4 and 4.7 of (3) cannot be new assertions. Indeed, instead they should be attributed to Theorems 4.3 and 4.5, and Example 4.6 of (10).
Could very high energy gamma rays from the crab nebula result from p-p collision?

It is generally believed that the very high energy (VHE) gamma rays emitted from the Crab Nebula cannot result from the decay of neutral pions which are produced by the collision between relativistic protons, due to the small hadronic cross section and low column density of the nebula. However, the magnetic field of the Crab Nebula could trap a large amount of relativistic protons from the pulsar with a total energy of up to 1047 erg, because this amount of energy is difficult to release for the same reason. Nevertheless, a small amount of protons will be converted to VHE photons through occasional hadronic collisions which result in steady VHE gamma ray emission with an average power of approximately 4*1034 erg s-1. The authors calculate the proton energy spectrum by using the pulsar evolution model proposed by Ruderman and Cheng (1988).
An association between H I concentrations within high-velocity clouds A and C and nearby molecular clouds

Data are presented identifying the CO and IR cirrus emission associated with concentrations of H I gas within a high-velocity cloud (HVC) A in Ursa Major (UMa) and a HVC CI B in Draco. It is found that H I concentrations within HVC A in UMa are associated with CO clouds estimated to be about 100 pc away, but the HVCs offset from the CO structures by about 5 deg on the sky. It is suggested that H I was swept out of the CO clouds about 100,000 yrs ago to create the HVCs. A similar phenomenon in Draco involved HVCs and IR cirrus clouds; the distance to the HVCs can be related to the nearby dust. A mean age of 200,000 yrs is found for these HVCs. 42 refs.
Non-compact gaugings from higher dimensions

The N=8 supergravity theories in four (and five) dimensions with non-compact gauge groups are obtained from eleven- (and ten-) dimensional supergravities in backgrounds with non-compact internal spaces. The SO(p,q) gaugings are obtained by a consistent truncation of the higher-dimensional supergravity in a background that is a warped product of a four- (or five-) dimensional Einstein space with the hyperboloid Hp,q (i.e. the surface (z1)2+. +(zp)2-(zp+1)2-. -(zp+q)2=r2). For the non-semisimple CSO (p,q,r) gaugings Hp,q is replaced by the 'cylinder' Hp,q*Rr. These backgrounds are solutions of the higher-dimensional field equations precisely when the lower-dimensional supergravity has a SO(p)*SO(q) invariant vacuum solution. The mode analysis and massive spectra in these backgrounds are briefly considered.
The fast Fourier transform applied to estimate wave energy spectral density in random sea state

This paper deals with an important area of real life problems. It is concerned with the application of the fast Fourier transform to estimate wave energy spectral density in a random sea state. Graphical illustrations are manifested in a clear and distinct manner. The fast Fourier transform is a mathematical procedure which can be thought of as transforming a function from the time domain to the frequency domain. The application of a Fourier transform is analogous to the splitting up of a light beam by a prism to form the optical spectrum of the light source. An optical spectrum consists of lines or beams of colors corresponding to the various wavelengths and hence different frequencies of light wave emitted by the source. The spectrum of a signal in digital signal processing refers to the way energy in the signal is distributed over its various frequency components.
Generalized Fokker-Planck equation for a class of stochastic dynamical systems driven by additive Gaussian and Poissonian fractional white noises of order α

In a first stage, the paper deals with the derivation and the solution of the equation of the probability density function of a stochastic system driven simultaneously by a fractional Gaussian white noise and a fractional Poissonian white noise both of the same order. The key is the Taylor’s series of fractional order f(x + h) = Eα(hαDxα)f(x) where Eα() denotes the Mittag-Leffler function, and Dxα is the so-called modified Riemann-Liouville fractional derivative which removes the effects of the non-zero initial value of the function under consideration. The corresponding fractional linear partial differential equation is solved by using a suitable extension of the Lagrange’s technique involving an auxiliary set of fractional differential equations. As an example, one considers a half-oscillator of fractional order driven by a fractional Poissonian noise.
Edge-based spatial concealment of digital dropout error in degraded archived media

A spatial concealment technique, based on the concept of the strength of an edge, is proposed for ‘digital dropout’ error, evident in old archived media. As long as the presence of pathological motion is observed in video sequences where current state-of-the-art methods fail to reproduce correct information, such spatial restoration offers a much better solution in terms of quality and complexity. Furthermore, relevant edge-based weighted interpolation is able to restore complicated edges and complex textures from the available neighbourhood. An experiment is performed on real video archives to evaluate the efficacy of the proposed technique.
Schottky barrier impact-ionization metal-oxide-semiconductor device with reduced operating voltage

In this letter, a Schottky barrier impact-ionization metal-oxide-semiconductor (SB-IMOS) device with reduced operating voltage is proposed and investigated. By introducing the silicide source and combining impact ionization with Schottky barrier tunneling, source parasitical resistance can be extremely reduced and the device performance can be improved. The device is optimized with Schottky barrier height variation additionally. Both SB-IMOS and conventional impact-ionization metal-oxide-semiconductor devices were fabricated using the standard complementary metal-oxide-semiconductor technology. SB-IMOS exhibits a 33% lower operating voltage, 43% lower threshold voltage, and improvement of ON current by 2 orders of magnitude while maintaining steep subthreshold swing of 10.2 mV/dec.
Photopolymer holographic recording material

Summary Photopolymers are promising materials for use in holography. They have many advantages, such as ease of preparation, and are capable of efficiencies of up to 100%. A disadvantage of these materials is their inability to record high spatial frequency gratings when compared to other materials such as dichromated gelatin and silver halide photographic emulsion. Until recently, the drop off at high spatial frequencies of the material response was not predicted by any of the diffusion based models available. It has recently been proposed that this effect is due to polymer chains growing away from their initiation point and causing a smeared profile to be recorded. This is termed a non-local material response. Simple analytic expressions have been derived using this model and fits to experimental data have allowed values to be estimated for material parameters such as the diffusion coefficient of monomer, the ratio of polymerisation rate to diffusion rate and the distance that the polymer chains spread during holographic recording. The model predicts that the spatial frequency response might be improved by decreasing the mean polymer chain lengths and/or by increasing the mobility of the molecules used in the material. The experimental work carried out to investigate these predictions is reported here. This work involved (a) the changing of the molecular weights of chemical components within the material (dyes and binders) and (b) the addition of a chemical retarder in order to shorten the polymer chains, thereby decreasing the extent of the non-local effect. Although no significant improvement in spatial frequency response was observed the model appears to offer an improved understanding of the operation of the material.
Investigations of pre-breakdown phenomena: streamer discharges

Physical principles of electrical breakdown are reviewed in this article. The phenomena of streamer formation and spontaneous branching are studied in terms of a fluid description based on kinetic theory. Particular attention is paid to a minimal model which is suitable for non-attaching gases. The evidence that anode directed fronts can branch due to a Laplacian instability is shown. Finally an electric shielding factor is introduced which allows us to extend previous results to curved geometries.