Miracle-dz/UniFAR-FTUs huggingface dataset:
Consistency of multivariate density estimators using random bandwidths

Asymptotic properties of a kernel density estimator using a random bandwidth are difficult to establish. Under some assumptions we prove the L1 consistency of a class of multivariate kernel density estimators using different bandwidth vector selectors. The expected L1 distance between such an estimator and the density is also shown to converge to zero. Our results hold even when the marginal densities are heavy-tailed. As a special case, we propose a simple estimator that depends on only one parameter, irrespective of the dimension. Its L1 distance from the density goes to zero, exponentially. Simulations suggest that this estimator performs well in terms of the integrated squared error as well.
On testing the proportionality of two cumulative incidence functions in a competing risks setup

A large sample test of proportionality of two cumulative incidence functions is developed for randomly right censored competing risks data without assuming that the K ≥ 2 risks are independent. The test is tailored to detecting monotonicity of the ratio of the two cumulative incidence functions and the test statistic is proved to be asymptotically normally distributed. In addition, it is shown that the proposed test can be readily adapted to test whether the censoring random variable and observable survival time have proportional hazards. The procedures are illustrated through application to two data sets well known in the survival analysis literature.
Using Panel Data to Estimate the Effects of Events

Although event history analysis provides a highly developed body of methods for studying the causes of events, there is little consensus on the best ways for studying the consequences of events. This article develops some methods for using multiwave panel data to estimate the effects of either naturally occurring events or planned interventions. It does this by synthesizing the literature on interrupted time series with econometric treatments of pooled time-series, cross-section data. The emphasis is on fixed-effects models and estimators because of their capacity to control for all stable differences across individuals, whether or not those differences are correlated with measured variables. In contrast to earlier treatments of the problem, the models allow for timevarying covariates and for events that can occur at different time periods for different individuals. For continuous dependent variables, the basic estimators are easily obtained with standard OLS regression programs. For dichotomous outcomes, logit models can be estimated by the method of conditional likelihood.
STRATEGY, NONTRANSITIVE DOMINANCE AND THE EXPONENTIAL DISTRIBUTION

Summary An easily programmed recursive formula for the evaluation of the distribution function of ratios of linear combinations of independent exponential random variables is developed. This formula is shown to yield the probability that one team beats another in a contest we call the special gladiator game. This game generates tournaments which exhibit nontransitive dominance and have some surprising consequences. Similar results are obtained for a recursive formula based on the geometric distribution.
Surface enhanced infrared absorption of octadecanethiol on wet-chemically prepared Au nanoparticle films

Surface enhanced infrared absorption of adsorbates on wet-chemically prepared Au islands was investigated using octadecanethiol as adsorbate. The preparation was done by letting Au nanoparticles adsorb on an oxidized silicon wafer surface followed by wet-chemically increasing the size of the Au nanoparticles. The surface enhanced infrared spectrum was measured in transmission geometry at normal incidence. Comparing the size of the antisymmetric CH2 stretch absorption of adsorbates on Au islands to the corresponding infrared reflection absorption signal on a 40nm thick smooth Au film gives an enhancement factor of about 2000.
Photoacoustic tomography using a fiber based Fabry-Perot interferometer as an integrating line detector and image reconstruction by model-based time reversal method

Photoacoustic imaging is based on the generation of acoustic waves in a semitransparent sample (e.g. soft tissue) after illumination with short pulses of light or radio waves. The goal is to recover the spatial distribution of absorbed energy density inside the sample from acoustic pressure signals measured outside the sample (photoacoustic inverse problem). If the acoustic pressure outside the illuminated sample is measured with a large-aperture detector, the signal at a certain time is given by an integral of the generated acoustic pressure distribution over an area that is determined by the shape of the detector. For example a planar detector measures the projections of the initial pressure distribution over planes parallel to the detector plane, which is the Radon transform of the initial pressure distribution. Stable and exact three-dimensional imaging with planar integrating detector requires measurements in all directions of space and so the receiver plane has to be rotated to cover the entire detection surface. We have recently presented a simpler set-up for exact imaging which requires only a single rotation axis and therefor the fragmentation of the area detector into line detectors perpendicular to the rotation axis. Using a two-dimensional reconstruction method and applying the inverse two-dimensional Radon transform afterwards gives an exact reconstruction of the three-dimensional sample with this set-up. In order to achieve high resolution, a fiber based Fabry-Perot interferometer is used. It is a single mode fiber with two fiber bragg gratings on both ends of the line detector. Thermal shifts and vibrations are compensated by frequency locking of the laser. The high resolution and the good performance of this integrating line detector has been demonstrated by photoacoustic measurements with line grid samples and phantoms using a model-based time reversal method for image reconstruction. The time reversed pressure field can be calculated directly by retransmitting the measured pressure on the detector positions in a reversed temporal order.
Propagation effects in optical-field-induced gas mixture breakdown for recombination x-ray lasers

A two-dimensional pulse propagation model which solves the paraxial wave equation in cylindrical geometry, is used to study argon doped with hydrogen targets. The code includes optical-field ionization, refraction and diffraction effects, above-threshold ionization and inverse bremsstrahlung electron heating mechanisms. A range of target and pump laser parameters are examined and a 4 mm long, wide channel may be formed which is suitable for x-ray lasing. A one-dimensional Lagrangian hydrodynamics model is subsequently used as a postprocessor to simulate the recombination phase with both the plasma effects and atomic kinetics included. Calculated gain coefficients above at 232 ? in Na-like Ar are found throughout the channel but with a saturation intensity of the order of .
Abnormal human activity recognition system based on R-transform and independent component features for elderly healthcare

This article presents a vision-based human activity recognition (HAR) system to recognize abnormal activities among a set of daily-life activities of elderly people. A novel method is proposed for feature extraction by the combination of R-transform, principal component analysis (PCA) and independent component analysis (ICA). R-transform is used for periodic, scale, and translation invariant feature extraction. PCA is used for dimensions reduction and ICA is used for independent features extraction. The features are processed by k-means to get observation sequences which are used by hidden Markov model for HAR. The dataset consisting of six abnormal activities (backward fall, forward fall, chest pain, headache, vomit, and faint) and three normal activities (walk, raise one hand, and raise both hands) from the view angles (90°, −90°, 45°, −45°, and 0°) is produced. Experimental results show average recognition rate of 86.86% for abnormal and normal activities from different view angles by our proposed system using (R-transform + PCA + ICA) as compared to R-transform, PCA, and ICA methods.
Magnetic circular x-ray dichroism and its relation to local moments

The study of magnetic XANES of circularly polarized x-rays at the K-edges and the L-edges in 3d-, 4f- and 5d-elements in ferro(i)magnetic materials is a powerful method to investigate in an element-selective manner magnetic aspects of the electronic structure of solids. It is demonstrated on the basis of simplified single-particle band-structure pictures that for 3d- and 5d-elements, which are polarized by 3d-neighbors, information on the local spin and orbital moments can be directly deduced from the magnetic L2,3-spectra similar to the application of the sum rules recently developed by T. Thole and P. Carra. Spin-polarized EXAFS studies of various systems are presented demonstrating the sensitivity of the SPEXAFS to the magnetic neighborhood only and their direct correlation to magnetic moments of neighboring atoms.
Controlling the plasma of deep penetration laser welding to increase power efficiency

During deep penetration laser welding, the plasma over the keyhole absorbs beam energy and reduces the power efficiency. The thermal movement of laser produced plasma is analysed theoretically and experimentally. A method to increase the electric current in the plasma is put forward. The principle and feasibility of controlling the plasma by electric and magnetic fields are discussed. An experimental procedure involving elevating the nozzle during laser welding is used to evaluate the effect of increasing the power efficiency by driving away the charged particles. The power efficiency increases with increasing magnetic field intensity. There is an optimal electric field intensity at which the power efficiency reaches its highest value. It is indicated that by applying proper electric and magnetic fields the charged plasma particles can be driven away and the power efficiency is increased.
Magnetic circuit analysis of a linear synchronous motor with permanent magnets

The authors describe a magnetic circuit analysis of a permanent-magnet-type synchronous motor using the finite element method. The effect of the size of the permanent magnets on the static thrust characteristics is investigated, and a prototype machine is fabricated on the basis of the results. Measured values of the static thrust and normal force of the prototype machine have been compared with the calculated values obtained by the finite element method. >
High-Resolution Radar Data Assimilation For Hurricane Isabel (2003) At Landfall

Major damage caused by hurricanes occurs over land during and after landfall. Accurate predictions of winds and precipitation in and around hurricanes at or near landfall are therefore of vital importance for hurricane preparation and damage mitigation, yet they continue to present a challenge for the hurricane research and numerical weather prediction (NWP) communities. This is, in part, due to rapid changes in hurricane intensity and structure during landfall associated with multiscale dynamical and physical interactions in the hurricane core regions and outer spiral rainbands, and also associated with sudden changes of surface conditions. In this study, we demonstrate the capability of improving predictions of hurricane intensity and structures near landfall by assimilating high-resolution, three-dimensional observations from land-based radars in the landfall regions into a mesoscale NWP model. The landfall of Hurricane Isabel on the east coast of the United States in 2003 is the focus of this study. O.
Shock Wave Stability in Steep Density Gradients

The stability of spherical accelerating shock waves is discussed via the examination of the stability of the new Waxman-Shvarts self-similar solutions to the strong explosion problem with a density profile ρ ∝ r-ω with ω > 3. We show that accelerating shock waves that diverge in finite time (obtained for ω larger than a critical value ωc: ω > ωc) are unstable for small and intermediate wavenumbers, in accordance with the conclusions of Chevalier, who studied the stability of planar shock wave propagating in an exponentially decaying density profile. However, accelerating shock waves that diverge in infinite time (obtained for ω < ωc) are stable for most wavenumbers. We find that perturbation of small wavenumber grow or decay monotonically in time, while perturbations of intermediate and high wavenumber oscillate in time.
The shock tube determination of the dissociative recombination rate of NO

The rate constant for dissociative recombination of NO+ was measured in the translational temperature range from 2800 to 4500 K using a shock tube technique. The rate was found to vary as alpha (T)=4.3(+or-0.8)*10-7(T/300)-0.7(+or-0.1) cm3 s-1. This measurement supports the view that there is no strong dependence on vibrational quantum number in the dissociative recombination of NO+.
DYNAMIC MECHANICAL PROPERTIES OF ARTERIAL AND VENOUS GRAFTS USED IN CORONARY BYPASS SURGERY

In this work we studied the frequency dependence of the dynamic mechanical characteristic s of saphenous vein (SV) and internal mammary artery (IMA) grafts. Rectangular longitudinal strips from 14 patients were tested under cyclic uniaxial tensile loading in the frequency range of 0.1–20 Hz, at 37°C in wet conditions. The dynamic mechanical parameters (the storage modulus ES and the hysteresis ratio h (loading/loop area)) together with the collagen phase modulus EH were computed as a function of frequency. The results showed that in all graft types ES and EH varied with frequency in the range 0.5–10 Hz, presenting a maximum in the neighboring of 1 Hz. The hysteresis ratio h was increased in the frequency range 1–20 Hz. It seems from the results that the physical resonance frequency of the components of the tissue responsible for their elastic behavior may lay in the range around 1 Hz, while that for the viscous behavior in the range of 20 Hz or more. Early clinical outcomes of both grafting were studied in parallel. In a one-year postoperative period the follow-up (clinical examination, electrocardiography, echocardiography and stress test) did not reveal any sign of graft occlusion or severe stenosis except one perioperative infraction but without any correlation to the graft quality.
SIZE AND SHAPE FROM STELLAR OCCULTATION OBSERVATIONS OF THE DOUBLE JUPITER TROJAN PATROCLUS AND MENOETIUS

We present results of a stellar occultation by the Jupiter Trojan asteroid Patroclus and its nearly equal size moon, Menoetius. The geocentric mid-time of the event was 2013 October 21 06:43:02 UT. Eleven sites out of 36 successfully recorded an occultation. Seven chords across Patroclus yielded an elliptical limb fit of 124.6 by 98.2 km. There were six chords across Menoetius that yielded an elliptical limb fit of 117.2 by 93.0 km. There were three sites that got chords on both objects. At the time of the occultation we measured a separation of 664.6 km (0.247 arcsec) and a position angle for Menoetius of 265. °7 measured eastward from J2000 north. Combining this occultation data with previous light curve data, the axial ratios of both objects are 1.3 : 1.21 : 1, indicative of a mostly oblate ellipsoid with a slight asymmetry in its equatorial projection. The oblate shape is not an equilibrium shape for the current rotation period, but would be if it were rotating with an ∼8 h period. This faster period is consistent with a pre-evolved state of the system with an orbital separation that is 50% smaller. Our best estimate of the system density is 0.88 g cm−3.
Multifield Hybrid Approach For Bubble ToSlug Flow Transition Modelling

This paper aims to assess a conservative interface locating method based on levelset adapted to two fluid model for two phase flow. The objective of the work is twofold: first to check out the prediction of the model on bubble coalescence cases and then to introduce a first description of the multifield hybrid approach for twophase flow modelling. The interface locating method is part of a model dedicated to the simulation of large and distorted bubbles. At different liquid viscosities and densities, the model yields reasonable predictions of terminal velocities and shapes for rising bubble experiments. The overall method relies also on an existing building block, consisting of a set of averaged models dedicated to dispersed bubbles, which has already been validated and has given a reasonable agreement with experimental data in cases where the spherical shape assumption is still valid for the dispersed phase. As a consequence, we present the first step toward a new approach consisting of modelling the small bubbles as a dispersed field and simulating the large and distorted ones. The main outcome is the simulation of bubble coalescence where the distortion of the interface during the coalescence phenomena is followed. The capability to simulate correctly coalescence phenomena is an important point of the modelling of slug flows with interface locating methods.
Stability of time-dependent rotational Couette flow Part 2. Stability analysis

The stability of the flow induced by an impulsively started inner cylinder in a Couette flow apparatus is investigated by using a linear stability analysis. Two approaches are taken; one is the treatment as an initial-value problem in which the time evolution of the initially distributed small random perturbations of given wavelength is monitored by numerically integrating the unsteady perturbation equations. The other is the quasi-steady approach, in which the stability of the instantaneous velocity profile of the basic flow is analyzed. With the quasi-steady approach, two stability criteria are investigated; one is the standard zero perturbation growth rate definition of stability, and the other is the momentary stability criterion in which the evolution of the basic flow velocity field is partially taken into account. In the initial-value problem approach, the predicted critical wavelengths agree remarkably well with those found experimentally. The kinetic energy of the perturbations decreases initially, reaches a minimum, then grows exponentially. By comparing with the experimental results, it may be concluded that when the perturbation kinetic energy has grown a thousand-fold, the secondary flow pattern is clearly visible. The time of intrinsic instability (the time at which perturbations first tend to grow) is about ¼ of the time required for a thousandfold increase, when the instability disks are clearly observable. With the quasi-steady approach, the critical times for marginal stability are comparable to those found using the initial-value problem approach. The predicted critical wavelengths, however, are about 1½ to 2 times larger than those observed. Both of these points are in agreement with the findings of Mahler, Schechter & Wissler (1968) treating the stability of a fluid layer with time-dependent density gradients. The zero growth rate and the momentary stability criteria give approximately the same results.
Empirical approximations for the Fermi energy in a semiconductor with parabolic bands

Approximate expressions are presented which are useful for computing the position of the Fermi level in a semiconductor when the carrier concentration is known. A simple approximation formula is applicable for η=EF/kT⩽5.7, while an extended approximation can be used up to η⩽20, the error in EF being less than 10−2kT in both cases.
Further high-resolution Na I observations of the local interstellar medium

High-resolution absorption measurements of the interstellar Na I D lines at 5890 A observed toward 27 early-type stars in the local interstellar medium (LISM) are presented. These results are combined with other high-resolution sodium measurements to map the space distribution of neutral sodium column density for some 118 stars out to less than 200 pc. These measurements indicate an upper limit to the neutral sodium column density of log N(Na I) less than 10.0/sq cm can be inferred out to a distance of 50 pc in most directions in the LISM. Also, the rarefield region of the Local Bubble may extend beyond 60 pc in at least 35 percent of the directions sampled thus far. Evidence is shown for a ubiquitous, comoving vector for neutral NaI gas clouds in the LISM which is in a different direction to LISM vectors previously reported for more ionized local gas clouds. A comparison of the measured sodium columns with those of interstellar Ca II for a sample of 12 stars within 95 pc results in a ratio of Na I/Ca II less than 0.5 for most stars. This value implies that there could be warm, neutral gas with T of about 12,500 K beyond 50 pc in the LISM.
Nanostructure and dielectric properties of a twist-bend nematic liquid crystal mixture

We present freeze-fracture transmission electron microscopy (FF-TEM), dielectric spectroscopy and electro-optic measurements on a dimeric liquid crystal mixture, which previously was proposed to form the twist-bend nematic (Ntb) phase. Our FF-TEM studies provide a direct image of a 10.5 nm periodic structure, consistent with the expected nanoscale, heliconical twist-bend modulation of the molecular orientation. Dielectric measurements in the 100 Hz to 10 MHz range reveal three nearly Debye-type dispersion processes in the nematic and the twist-bend phase. Low frequency 8 V/µm electric fields applied on planar cells cause the optical-scale stripe texture (another characteristic feature of the Ntb phase) to disappear. Higher (>16 V/µm) fields gradually realign the heliconical axis along the electric field; it relaxes back after the field removal.
Prediction of resistive and hysteretic losses in a multi-layer high-Tc superconducting cable

In this work, a model of a multi-layer high-Tc superconducting (HTS) cable that computes the current distribution across layers as well as the AC loss is presented. Analyzed is the case of a four-layer cable, but the developed method can be applied to a cable with an arbitrary number of layers. The cable is modelled by an equivalent circuit consisting of the following elements: nonlinear resitances, linear self and mutual inductances, as well as nonlinear, hysteretic inductances. The first take into account the typical current-voltage relation for superconductors, the second introduce coupling among the layers and depend on the geometrical parameters of the cable, the third describe the hysteretic behaviour of superconductors. In the presented analysis, the geometrical dimensions of the cable are fixed, except for the pitch length and the winding orientation of the layers. These free parameters are varied in order to partition the current across the layers such that the AC loss in the superconductor is minimized. The presented model allows to evaluate rapidly the current distribution across the different layers and to compute the corresponding AC loss. The rapidity of the computation allows calculating the losses for many different configurations within a reasonable time. The model has so firstly been used for finding the pitch lengths giving an optimal current distribution across the layers and for computing the corresponding AC loss. Secondly, the model has been refined taking into account the effects of the magnetic self-field, which, especially at high currents, can sensibly reduce the transport capacity of the cable, in particular in the outer layers.
Electrostatic energy analyzer using a nonuniform axial magnetic field

Electrostatic electron energy analysis in a strong magnetic field using conventional retarding‐field methods may be inaccurate, because these devices discriminate against parallel momentum and not total energy. We show how a magnetic‐field minimum at the point of minmum potential can remove this difficulty. Examples of elastic and inelastic electron–atom scattering, and of electron energy loss in a plasma, are given.