Miracle-dz/UniFAR-FTUs huggingface dataset:
Fabrication of Si nanostructures with an atomic force microscope

A method for fabricating Si nanostructures with an air‐operated atomic force microscope (AFM) is presented. An electrically conducting AFM tip is used to oxidize regions of size 10–30 nm of a H‐passivated Si (100) surface at write speeds up to 1 mm/s. This oxide serves as an effective mask for pattern transfer into the substrate by selective liquid etching. The initial oxide growth rate depends exponentially on the applied voltage which produces an effective ‘‘tip sharpening’’ that allows small features to be produced by a relatively large diameter tip.
LOCAL SMOOTH SOLUTIONS OF A THIN SPRAY MODEL WITH COLLISIONS

Sprays are complex flows made of liquid droplets surrounded by a gas. The aim of this paper is to study the local in time well-posedness of a collisional thin spray model, that is a coupling between Euler equations for a perfect gas and a Vlasov–Boltzmann equation for the droplets. We prove the existence and uniqueness of (local in time) solutions for this problem as soon as initial data are smooth enough.
Triplet energy transfer in conjugated polymers. III. An experimental assessment regarding the influence of disorder on polaronic transport

It is a general notion that, in organic semiconductors, the transport of electronic excitations, such as neutral excitons of singlet or triplet type and charge carriers, is controlled by both, polaron and disorder effects. For compounds with low energetic disorder triplet exciton diffusion can be described in the framework of Marcus-theory [see Sudha Devi et al.,Phys. Rev. B 78, 045210 (2008)], and a theoretical model for diffusion in more disordered compounds has been developed [see Fishchuk et al., Phys. Rev. B 78, 045211 (2008)]. Here we experimentally demonstrate that such a modified Marcus-type model is suitable to describe triplet exciton transport in commonly used poly($p$-phenylene)-type polymers and oligomers. In particular, we provide a quantitative spectroscopic assessment of the polaronic and the disorder contribution to triplet exciton transport as a function of conjugation length. Franck-Condon analyses of the phosphorescence spectra and temperature-dependent triplet diffusion combined with analytic transport theory demonstrate that, in contrast to charge carriers, Marcus-type jump rates with dominantly polaronic activation energies control the motion of triplet excitons above a transition temperature.
Single star scattering on an open cluster

We examine the scattering of single stars from an open star cluster. The probability of the capture of a star by a star cluster is dependent on the velocity and mass of the star, and the stars that are not captured experience a velocity change. For low-velocity stars there is an exponential decrease of the capture probability with the initial velocity, and the velocity change decreases almost linearly. For high-velocity stars there is a v −6 dependence for the capture probability, and a v −1 dependence for the velocity change. Analytical estimations, Monte Carlo and full N-body simulations are all in good agreement.
Central Difference Kalman-probability Hypothesis Density Filter for Multiple Speakers Tracking

Aiming at nonlinear system model in multiple speakers tracking, a central difference Kalman-probability hypothesis density filter for multiple speakers tracking is proposed in this paper. Time difference of arrival for microphone array is taken as measurement, Stirling interpolation formula is utilized to derive polynomial approximations of nonlinear functions, central difference Kalman filter and Gaussian mixture probability hypothesis density filter are applied to estimate first-order statistical moment of posterior multiple speakers states, and finally multiple speakers tracking of nonlinear Gaussian system is realized while the speakers states are extracted by recursive updating. Simulation results show that the robustness of the algorithm is enhanced, and estimation accuracy of multiple speakers number and states is improved.
Multidimensional time-correlated single photon counting

Time-correlated single photon counting (TCSPC) is based on the detection of single photons of a periodic light signal, measurement of the detection time of the photons, and the build-up of the photon distribution versus the time in the signal period. TCSPC achieves a near ideal counting efficiency and transit-time-spread-limited time resolution for a given detector. The drawback of traditional TCSPC is the low count rate, long acquisition time, and the fact that the technique is one-dimensional, i.e. limited to the recording of the pulse shape of light signals. We present an advanced TCSPC technique featuring multi-dimensional photon acquisition and a count rate close to the capability of currently available detectors. The technique is able to acquire photon distributions versus wavelength, spatial coordinates, and the time on the ps scale, and to record fast changes in the fluorescence lifetime and fluorescence intensity of a sample. Biomedical applications of advanced TCSPC techniques are time-domain optical tomography, recording of transient phenomena in biological systems, spectrally resolved fluorescence lifetime imaging, FRET experiments in living cells, and the investigation of dye-protein complexes by fluorescence correlation spectroscopy. We demonstrate the potential of the technique for selected applications.
Properties of joint gaussian statistics

In this paper joint- or complex-gaussian statistics are assumed to apply to the in-phase and quadrature components of an electromagnetic wave which has propagated through a turbulent medium, and the consequences of this assumption are compared to tropospheric, ionospheric, and laboratory propagation experiments. New curves for the cumulative probability distribution of intensity and for the variance of intensity versus the variance of the logarithm of intensity are presented. Joint-gaussian statistics are shown to fit the total set of turbulence propagation results better than the log-normal, Rice-Nakagami, or Nakagami-m distributions. However, a major feature of optical observations cannot be fit by joint-gaussian statistics: the straight-line cumulative intensity distributions in the saturation regime that reflect a large probability of occurrence of high intensity spikes.
Composition of nonthermal ions in the Jovian magnetosphere

We present observations from Voyager 1 and 2 of nonthermal ions from H through Fe in the Jovian magnetosphere using the low-energy particle telescope (LEPT), one of the two sensors of the low-energy charged particle (LECP) experiment. At ∼1 MeV/nucleon the major constituents of the ion population were H, He, C, O, Na, S, and the hydrogen molecules H2 and H3. Relative to He, the abundance of H and H3 at equal energy/nucleon was highest in the outer magnetosphere, the abundance of O, Na, and S was highest in the inner magnetosphere, and the abundance of C was constant throughout the magnetosphere. He and C may be of largely solar origin, while H2, H3, O, Na, and S are largely of local origin. The variations in abundance ratios were accompanied by a general hardening of the energetic particle spectra near 1 MeV/nucleon with decreasing radial distance. We are able to find a parameter η, assumed to be a species-dependent constant times energy/nucleon, in terms of which the flux ratios among most species do not change with radial distance. These ‘invariant’ ratios indicate that there are approximately equal numbers of nonthermal O, S, and He ions, with the abundance of H ions being a factor of ∼15 higher. The large ratio changes at equal energy/nucleon can then be ascribed to the changing spectral slopes. The parameter η may be reasonably identified with energy/charge, in which case we are able to deduce relative charge to mass ratios for H, He, C, O, and S. If He is doubly ionized, we find that the nonthermal carbon has an approximate charge state of +6, typical of solar wind particles, while oxygen and sulfur have low charge states (+2 to +4), typical of local plasma sources. Spectral changes over the range of ∼30 to ∼16 RJ, in this interpretation, are consistent with particle energization by inward radial diffusion conserving the first adiabatic invariant. In the Jovian magnetotail, at the time of the Voyager 2 outbound pass, the energetic particle population was a combination of Jovian particles with soft spectra and interplanetary particles (probably of solar flare origin) with much harder spectra. Above ∼1 MeV/nucleon the interplanetary particles were dominant. Beyond ∼160 RJ, in the ‘magnetospheric wind’ region, the nonthermal ion intensity increased and reflected an oxygen-and sulfur-rich composition typical of the middle magnetosphere. Two short-lived intensity increases were observed at ∼290 RJ which had heavy ion abundance ratios and spectra similar to those found in the inner magnetosphere. The release of these particles was apparently associated with the arrival at Jupiter of a fast solar wind stream.
Tests of randomness based on distance methods

The most familiar method of testing the hypothesis that an observed spatial distribution of points in the Euclidean plane is a realization of a Poisson point process, or in practical terminology that the points are distributed 'completely at random' is based on the Index of Dispersion. In recent years, however, statistical ecologists have shown interest in what are known as distance, or nearest neighbour methods for studying the pattern of plant distributions. These involve choosing a set of n sampling points in a fixed sampling area B according to some rule, and measuring the distances Xij from the ith sample point to the jth nearest plant to it, measurements to plants outside B being permitted if necessary. The observations Xij are then used in estimators of the density of the spatial point process of which the plant distribution is a realization, or in testing hypotheses about its form. Distance methods have been discussed by Skellam (1952), Strand (1953), Moore (1954), Hopkins (1954), Thompson (1956), Matern (1959), Pielou (1959), Mountford (1961), Kendall & Moran (1963, p. 38), Keuls, Over & De Wit (1963), Persson (1964) and Holgate (1964, 1965 a, b). Tests of randomness based wholly or partly on distance methods have been proposed by Skellam, Moore, Hopkins and Pielou (see also Mountford's paper). These tests are discussed in the present paper, with particular emphasis on their power to detect certain kinds of departure from randomness. In Holgate (1965a) two more tests are proposed and discussed.
Scintillation Effects on a High-Contrast Imaging Instrument for Direct Extrasolar Planets' Detection

A study of the scintillation effects on the point-spread function (PSF) halo of the high-contrast imaging instrument (Characterization of Exoplanets by Opto-Infrared Polarimetry and Spectroscopy [CHEOPS]) for direct exoplanet detection from the ground is presented. The fundamental goal of our analysis is to quantify the perturbations induced by the amplitude (scintillation) variations compared with those induced by the phase variations of a perturbed wave front. Simulations of amplitude and phase screens are obtained for different seeing conditions and for a wave front propagating at different zenith angles. For all cases, a set of simulations of the PSFs in the ideal mirror-limited case (perfect wave front sensor and adaptive optics system) and an estimation of the detection limit Δm versus angular separation obtained with and without scintillation are presented. The whole study is made in the I band (λ = 0.9 μm), i.e., the centered wavelength of the CHEOPS polarimetric imager. A maximum loss of contrast (obtained with and without scintillation) of ~25% over a field of view of 5'' is found in the speckle noise-limited regime, and ~18% in the photon noise-limited regime. Results are discussed, and conditions in which the scintillation effects cannot be neglected are investigated.
Recursive Estimation of Conditional Spatial Medians and Conditional Quantiles

Abstract We consider the problem of constructing an on-line (recursive) algorithm for tracking a conditional spatial median, a center of a multivariate distribution. In the one-dimensional case we also track conditional quantiles of arbitrary level. We establish a nonasymptotic upper bound for the L p -risk of the algorithm, which is then minimized under different assumptions on the magnitude of the variation of the spatial median or quantile. We derive convergence rates for the examples we consider.
In situ determination and imaging of physical properties of metastable and equilibrium precipitates using valence electron energy-loss spectroscopy and energy-filtering transmission electron microscopy

The physical (elastic, cohesive, and electronic) properties of precipitates are important in determining factors such as their equilibrium shape, coarsening, and strengthening behavior in alloys. In this work, we use valence electron energy-loss spectroscopy (VEELS) and energy-filtering transmission electron microscopy (EFTEM) to determine quantitatively and image the elastic moduli, cohesive energy, and interstitial electron density of both metastable and equilibrium precipitates in two different metal alloys. We show that the elastic properties of θ′ and θ precipitates in Al–Cu alloys can be measured in situ as a function of temperature and during transformation from θ′ and θ phases. We also measure and image in situ the elastic and cohesive properties of metastable TiHx precipitates in a Ti–H alloy. These results demonstrate the capability of VEELS∕EFTEM for real-time nanoscale determination and imaging of multiple physical properties of precipitates in solid-solid phase transformations.
Asteroseismology of the Multiply Periodic δ Scuti Star θ Tucanae

We present an asteroseismological analysis of the δ Scuti component of the binary star system θ Tucanae, using the 10 pulsational frequencies obtained photometrically by Paparó et al. and the mode identifications of Sterken. We have tested theoretical models with masses between 1.8 and 2.8 M☉ that have solar metal abundances, and we find that based upon mode stability arguments, the photometrically derived mass estimate of 2.1 ± 0.1 M☉ is probably accurate. The models with the best frequency match to θ Tucanae have masses of 1.9-2.1 M☉, luminosities between 20 and 25 L☉, effective temperatures between 7500 and 7685 K, log g values between 3.82 and 3.92, and rotational velocities between 70 and 90 km s-1. The luminosities of our models are more than a factor of 2 less than the Hipparcos-derived luminosity of 54 L☉, which suggests that the secondary star must be of comparable luminosity. We cannot determine whether tidal distortion is causing nonspherical perturbations in the pulsating component of this system with our current models, but the frequency spacing of observed pulsation modes suggests that rotation has a strong effect on the observed spectrum. Our models are consistent with the observed pulsation spectrum if rotational splitting is taken into account. Recently, De Mey, Daems, & Sterken determined spectroscopically that the θ Tucanae system is a spectroscopic binary with an anomalous mass ratio of 0.0896. In their model of this system, the δ Scuti component of the system is probably the beneficiary of mass transfer from the secondary, and the system was likely once an Algol-type system. The secondary is probably a 0.2 M☉ post-red giant branch object at ~7000 K (log g ~ 3.0), which has lost most of its mass via mass transfer and winds. This scenario raises the possibility that the interior of the δ Scuti star may be radically different from what single-star evolution models predict, although our results do not show any obvious differences. However, the age and envelope abundances should be different from single-star model predictions. We believe that this object provides an excellent opportunity to study the interiors of post-mass transfer objects using asteroseismology, and we suggest future observational and theoretical work that will help us understand this system.
Spectra of X-ray bursts at near-Eddington luminosities

Nnumerical and analytical models of photospheres of X-ray bursters have been developed for the case when the burster luminosity is very close to the Eddington limit, l = L/L Ed = 0.9-0.999. It is shown that the burst spectrum at observable energies can be described by a diluted Wien spectrum with spectrum temperature T coinciding with the electron temperature in an isothermal outer layer formed by Compton heating in the neutron star photosphere. The dilution factor is proportional to (T eff /T) 4 .
Magnetohydrodynamic Boundary Layer Flow of Nanofluid over an Exponentially Stretching Permeable Sheet

A mathematical model of the steady boundary layer flow of nanofluid due to an exponentially permeable stretching sheet with external magnetic field is presented. In the model, the effects of Brownian motion and thermophoresis on heat transfer and nanoparticle volume friction are considered. Using shooting technique with fourth-order Runge-Kutta method the transformed equations are solved. The study reveals that the governing parameters, namely, the magnetic parameter, the wall mass transfer parameter, the Prandtl number, the Lewis number, Brownian motion parameter, and thermophoresis parameter, have major effects on the flow field, the heat transfer, and the nanoparticle volume fraction. The magnetic field makes enhancement in temperature and nanoparticle volume fraction, whereas the wall mass transfer through the porous sheet causes reduction of both. For the Brownian motion, the temperature increases and the nanoparticle volume fraction decreases. Heat transfer rate becomes low with increase of Lewis number. For thermophoresis effect, the thermal boundary layer thickness becomes larger.
Nonlinear optical performance of periodic structures made from composites of polymers and Co3O4 nanoparticles

The nonlinear optical performance of specially designed periodic structures made from composites of optical polymers and Co3O4 nanoparticles is investigated. The refractive indices of the alternating layers are designed to be close and no photonic band gap (PBG) is formed at low power density. Under high power illumination, the index difference becomes large because of the high optical nonlinearities of the Co3O4 nanoparticles. Consequently, enhanced nonlinear optical performance is obtained with the formation and the strengthening of the PBG. Nonlinear reflection and nonlinear transmission as well as reduced nonlinear threshold are observed in the PBG structures.
Piezoresistive torque magnetometry below 1 K

We have investigated the performance of piezoresistive cantilevers as magnetometers in the temperature range below 1 K. The de Haas-van Alphen effect was used to study the temperature dependence of a sample of κ-(BEDT-TTF)2Cu(NCS)2, fixed on the end of a cantilever, as a function of the excitation current through the piezoresistive device. We found that by using a small thermalizing wire connected directly to the sample, large excitations were not incompatible with sample temperatures remaining low, thereby establishing the use of these devices as sensitive magnetometers well below 1 K. A large hysteretic behavior observed at low fields (below 0.01 T) and low temperature (below ∼2 K) precludes their use in that regime.
A CHARACTERIZATION OF TOTAL GRAPHS

I. ABSTRACT. We consider "ordinary" graphs; that is, finite undirected graphs with no loops or multiple edges. The total graph T(G) of a graph G is that graph whose vertex set is V(G)JUE(G) and in which two vertices are adjacent if and only if they are adjacent or incident in G. A characterization of regular total graphs as well as some other properties of total graphs have been considered before. In this article we consider nonregular graphs and yield a method which enables us actually to determine whether or not they are total.
Analysis of V defects in GaN-based light emitting diodes by scanning transmission electron microscopy and electron beam induced current

In the fabrication of InGaN∕GaN multiple quantum well light emitting diodes so-called V defects are common, but little is known about their electrical activity. Scanning transmission electron microscopy is capable of directly observing these defects, while electron beam induced current (EBIC) techniques can be used to probe electronic behavior of semiconductor defects. These techniques were combined to obtain localized measurements and our results indicate that V defects suppress the EBIC signal near the core of the defect and produce a displacement in the p-n junction location. Furthermore, the EBIC profile suggests that minority carrier diffusion lengths are longer inside the defect.
The Forcing of Gravitational Normal Modes by Condensational Heating

Abstract Time series of normal mode coefficients were determined by projection of data produced at every time step for 64 days of a long climate simulation with the NCAR Community Climate Model. Harmonic dials and power spectra for selected gravitational modes were examined. One result is that the greatest power for gravitational modes is typically at the longest periods examined, but noteworthy relative maxima also occur near a mode's resonant period and corresponding time-computational period. For most naturally fast modes, the power at long periods tends to be many times greater than the power near the resonant period, implying that the behavior of these modes may be characterized as approximately balanced. For naturally slow modes, such as Kelvin modes, however, the portion of power near the mode's resonant period is often nonnegligible, implying that these modes are characterized by quasi-linear, wavelike propagation, rather than by either diabatic or adiabatic balance behavior. For the same simulate.
Residuals for relative risk regression

SUMMARY Several possible definitions of residuals are given for relative risk regression with time-varying covariates. Each such residual has a representation as an estimator of a stochastic integral with respect to the martingale arising from a subject's failure time counting process. Previously proposed residuals for individual study subjects and for specific time points are shown to be special cases of this definition, as are previously derived regression diagnostics. An illustration and various generalizations are also given. able methods are required to detect various departures from modelling assumptions. Suitably defined residuals may play an important role in such identification. However, the nonparametric aspect of the model, the possibility that modelled regression variables may be varying with follow-up time and, most importantly, the usual presence of right censorship, implies that specialized residual definitions are required. The class of residuals considered here is most easily formulated using counting process notation for the failure time data. Let Ni(t), Yi(t) and Zi(t) represent, respectively, for the ith subject the values of counting, censoring and covariate processes at follow-up time t (i = 1, . . ., n), while {Ni(u), Yi(u), Zi(u); 0C u < t} specifies the corresponding histories for the ith subject prior to time t. Thus in a typical univariate failure time application, Ni, with right- continuous sample paths, will take value zero prior to the time of failure on the ith subject and value one thereafter, while Yi with left-continuous sample paths will take value one at times at which the ith subject is 'at risk' for an observed failure, and value zero otherwise. The counting process Ni can be uniquely decomposed so that for all (t, i)