Miracle-dz/UniFAR-FTUs huggingface dataset:
Subgap states in transparent amorphous oxide semiconductor, In–Ga–Zn–O, observed by bulk sensitive x-ray photoelectron spectroscopy

We investigated the electronic states in amorphous In–Ga–Zn–O films with high carrier concentrations by optical absorption and hard x-ray photoelectron spectroscopy (HX-PES). Films having different Hall mobilities were prepared and their annealing effects were examined. All HX-PES spectra showed Fermi edge structures and extra subgap densities of states (DOSs). Tail-like structures observed in the optical spectra originate from subgap DOSs (⪢1020cm−3) near valence band maximas (VBMs). Subgap DOSs near VBMs provide a reason why In–Ga–Zn–O thin film transistors show hard saturation in off states and are difficult to operate in an inversion p-channel mode.
Properties of the Ensemble Kalman Filter

Data assimilation is used in numerical weather prediction to improve weather forecasts by incorporating observation data into the model forecast. The Ensemble Kalman Filter (EnKF) is a method of data assimilation which updates an ensemble of states and uses this to provide a state estimate and associated error estimate at each step. Some implementations of the EnKF, such as the Ensemble Transform Kalman Filter (ETKF), have been found to exhibit undesirable behaviour. This dissertation investigates two such problems exhibited by the ETKF: ensemble collapse and bias. A solution to the ensemble collapse problem using random rotations is given and experimental results with the ETKF with the random rotations applied are presented. The conditions for an EnKF to be unbiased are examined, and these conditions are used to determine further restrictions on the random rotations to ensure that applying them to the filter will not introduce a bias. An unbiased filter with random rotations is developed and experimental results with this new filter show that it does not exhibit the ensemble collapse problem, and that it is unbiased.
Multi-epoch interferometric observations of the Be star ζ Tau

Abstract We present interferometric observations of the Be star ζ Tau obtained using the MIRC beam combiner at the CHARA Array during four epochs in 2007–2009. Fitting a geometric model to the data reveals a nearly edge-on disk with a FWHM of ~1.8 milli-arcsec in the H-band. The non-zero closure phases indicate an asymmetry in the brightness distribution. Interestingly, when combining our results with previously published interferometric observations of ζ Tau, we find a correlation between the position angle of the disk and the spectroscopic V/R ratio, suggesting that the tilt of the disk might be precessing. This work is part of a multi-year monitoring campaign to investigate the development and outward motion of asymmetric structures in the disks of Be stars.
Acoustic Surface‐Wave Beam Diffraction on Anisotropic Substrates

The diffraction of any distribution can be discussed in terms of its constituent Gaussian modes. Simple design formulas are developed from a two‐dimensional diffraction theory in order to characterize Gaussian beam diffraction in terms of three readily determined anisotropic propagation coefficients. The relationship between these coefficients and known anisotropic propagation phenomena is explored. Beam steering, diffraction, and focusing effects are discussed in some detail. Attention is drawn to two particular effects: autocollimation and ``negative'' phase front curvature. Situations in which both occur in practice are discussed. The former should play a significant role in acoustic matched filter design. A cylindrical transducer is shown, within limits, to be an optimum structure for obtaining a single acoustic beam convergence, even in the presence of beam scattering. The parabolic diffraction theory is applied to the design of an experimental anisotropic focusing system.
The scale of the magnetotail reconnecting current sheet in the presence of O+

The reconnection current layer thickness is expected to scale with either the ion inertial length or the ion gyroradius. Both of these quantities scale with the mass of the ions present. During geomagnetically disturbed times, the reconnection layer in the magnetotail can contain a significant amount of O+. Using Cluster multi‐spacecraft measurements, we have studied nine reconnection events in the magnetotail plasmasheet, to determine whether the reconnecting current sheet thickness scales with the ion gyroradius or the ion inertial length, and whether the amount of O+ in the plasma sheet has an effect on the current layer thickness. We find that the thickness is equal to the H+ gyroradius, even when the plasma sheet has a high O+ content. This result is in contrast to Hall MHD expectations and likely results from the multiscale nature of the current sheet.
Observability analysis of piece-wise constant systems with application to inertial navigation

A method for analyzing the observability of time-varying linear systems which can be modeled as piecewise constant systems is presented. An observability matrix for such systems is developed for continuous and discrete time representations. A stripped observability matrix is introduced which simplifies the analysis in cases where the use of this matrix is legitimate. This approach circumvents the difficulty associated with the investigation of the observability Gramian of time-varying linear systems. It is shown that instead of investigating a Gramian, only a constant observability matrix needs to be investigated. Moreover, it is shown that if certain conditions on the null space of the dynamics matrix of the system are met, the observability matrix can be greatly simplified. A step-by-step observability analysis procedure is presented for this case. The method is applied to the analysis of in-flight alignment of inertial navigation systems whose estimability is known to be enhanced by maneuvers. <<ETX>>
Mechanics of Fluid-Rock Systems

Most of the Earth's mass is solid. The crust and mantle of the Earth extend down almost 3000 km and support seismic shear waves, a standard test for solidity in the earth sciences. The inner core, with a radius of 1200 km, is believed to be solid for the same reason. It is less often noted that in large regions, this solid mass is actually a two-phase or multiphase medium, containing varying amounts of fluid (usually liquid) interspersed throughout the granular solid. Processes in fluid-rock media play an essential role in many important geological phenomena. It is percolation through such a medium (a partial melt) that permits melts to escape prior to volcanic eruptions and other igneous emplacements. Nearer the Earth's surface, the migration of aqueous or hydrocarbon fluids in the crust is of interest in metamorphic and sedimentary geology as well as in hydrology and hydrocarbon exploration. Fluid migration at all levels within the Earth can profoundly influence heat flow and material transport. The layering of the Earth, including the existence and nature of the core and the stratification of the mantle and crust, is likely to be due in part to the behavior of fluid-rock systems. There are many different fluid-rock systems in geology, and this review considers only a subset of these. The primary emphasis is on two geologic environments where the coupling between fluid flow and rock deformation is important: high-temperature systems where a melt coexists with a solid matrix that can deform by creep as the melt migrates; and low-temperature systems where a fluid, usually aqueous, saturates a matrix that has varying degrees of cohesion and fracturing. We do not consider suspensions (e.g. crystals in a convecting magma chamber or rock fragments carried in the plume of a volcanic eruption). At the opposite extreme, we exclude solidlike systems where fluid is present but little or no fluid movement occurs (e.g. fluid inclusions in crystals). Minor consideration is given to systems where the fluid moves but the solid is essentially rigid (e.g. the flow of oil, water, and gas in hydrocarbon reservoirs). We also limit ourselves to processes where inertia is negligible: Both the microscopic motion of fluid through cracks and pores and the macroscopic motion of the solid matrix are assumed to be characterized by a small Reynolds number. For example, we do not consider seismic-wave propagation in poroelastic media. Even with these restrictions, more important geodynamic phenomena are covered than can be effectively reviewed in detail. Our goal is rather to identify common ground between studies of different geological environments, and to demonstrate to practitioners of fluid mechanics the interesting range of phenomena that fluid-rock systems exhibit. We have divided the main body of this review into three sections: theory, material properties, and modeling and applications. The latter section is necessarily eclectic but encompasses studies ranging from laboratory experiments on analogue systems to computer simulations of large-scale processes in the crust and mantle.
Differential population synthesis of S0 galaxies. II. Methods and results

The integrated spectra of the disk and nuclei of a sample of S0 galaxies are compared to those of normal elliptical galaxies using a differential technique to search for and analyze any possible differences between the two galaxy types. A fiducial elliptical sequence representing stellar populations of uniform age but variable metallicity is constructed. Comparison of the S0 disk spectra to this sequence at a location appropriate for their line strengths reveals the presence, in roughly half of the S0 disks studied, of hot subpopulations which are not present in normal ellipticals. These subpopulations can contribute from 5 percent to as much as 50 percent or more of the V light in a particular S0 disk. It is argued that the subpopulations can be divided into two categories: those that are similar to the solar neighborhood population and are actively forming stars; and those that are older, intermediate-age populations. This supports the view that S0 galaxies have evolved from spiral or spiral-like galaxies. 45 references.
Self-consistent full-wave and Fokker-Planck calculations for ion cyclotron heating in non-Maxwellian plasmas

Magnetically confined plasmas can contain significant concentrations of nonthermal plasma particles arising from fusion reactions, neutral beam injection, and wave-driven diffusion in velocity space. Initial studies in one-dimensional and experimental results show that nonthermal energetic ions can significantly affect wave propagation and heating in the ion cyclotron range of frequencies. In addition, these ions can absorb power at high harmonics of the cyclotron frequency where conventional two-dimensional global-wave models are not valid. In this work, the all-orders global-wave solver AORSA [E. F. Jaeger et al., Phys. Rev. Lett. 90, 195001 (2003)] is generalized to treat non-Maxwellian velocity distributions. Quasilinear diffusion coefficients are derived directly from the wave fields and used to calculate energetic ion velocity distributions with the CQL3D Fokker-Planck code [R. W. Harvey and M. G. McCoy, Proceedings of the IAEA Technical Committee Meeting on Simulation and Modeling of Thermonuclear .
Microquasar: Disk Models

Basic disk models are reviewed with special attention on the dynamics of near- or super-critical accretion regimes. High accretion-rate flows are observed in many different systems and interaction between radiation and gas is key physics in this regime. GRS 1915+105 seems to probe the presence of transitions between the standard-disk and slim-disk branches. At even higher accretion rates (> LE/c2), significant photon trapping effects appear, leading to spectral softening, because hard photons are more effectively trapped by the flow.
The Neutron Component in Fireballs of Gamma-Ray Bursts: Dynamics and Observable Imprints

We analyze the dynamics of a neutron-proton relativistic wind, paying particular attention to fireballs of cosmological gamma-ray bursts (GRBs). Specific effects of the neutron component depend on whether the final Lorentz factor of a plasma wind exceeds some critical value or not. In the first case, velocity decoupling of the neutron and proton flows takes place, giving rise to an electromagnetic cascade induced by pion production in inelastic collisions of nucleons. Otherwise, all nucleons in the wind behave as a single fluid. In both cases neutrons can strongly influence a GRB by changing the dynamics of a shock initiated by protons in the surrounding medium. Conditions for the decoupling of the neutron flow as well as observational consequences of the resulting pion-induced cascade are discussed, including preburst of high-energy photons and neutrinos and annihilation afterglow of a huge number of ejected electron-positron pairs. The critical value of the Lorentz factor is estimated to lie in the range expected for cosmological GRBs, so there possibly exist two different populations of bursts. A number of tests for decoupling of the neutron flow is suggested. The results obtained for the radiation-driven wind allow straightforward generalization for winds driven by other mechanisms, e.g., for the MHD winds.
Impact of active geomagnetic conditions on stimulated radiation during ionospheric second electron gyroharmonic heating

Recently, narrowband emissions ordered near the H+ (proton) gyrofrequency (fcH) were reported in the stimulated electromagnetic emission (SEE) spectrum during active geomagnetic conditions. This work presents new observations and theoretical analysis of these recently discovered emissions. These emission lines are observed in the stimulated electromagnetic emission (SEE) spectrum when the transmitter is tuned near the second electron gyroharmonic frequency (2fce) during recent ionospheric modification experiments at the High Frequency Active Auroral Research (HAARP) facility near Gakona, Alaska. The spectral lines are typically shifted below and above the pump wave frequency by harmonics of a frequency roughly 10% less than fcH (≈ 800 Hz) with a narrow emission bandwidth less than the O+ gyrofrequency (≈ 50 Hz). However, new observations and analysis of emission lines ordered by a frequency approximately 10% greater than fcH are presented here for the first time as well. The interaction altitude for the heating for all the observations is in the range of 160 km up to 200 km. As described previously, proton precipitation due to active geomagnetic conditions is considered as the reason for the presence of H+ ions known to be a minor background constituent in this altitude region. DMSP satellite observations over HAARP during the heating experiments and ground‐based magnetometer and riometer data validate active geomagnetic conditions. The theory of parametric decay instability in multi‐ion component plasma including H+ ions as a minority species described in previous work is expanded in light of simultaneously observed preexisting SEE features to interpret the newly reported observations. Impact of active geomagnetic conditions on the SEE spectrum as a diagnostic tool for proton precipitation event characterization is discussed.
Heart-shaped bubbles rising in anisotropic liquids

This Letter reports on numerical simulations motivated by experimental observations of an unusual inverted-heart shape for bubbles rising in an anisotropic micellar solution. We explain the bubble shape by assuming that the micelles are aligned into a nematic phase, whose anchoring energy on the bubble competes with the interfacial tension and the bulk elasticity of the nematic to modify the interfacial curvature. Numerical results show that bubbles with sufficiently strong planar anchoring rising in a vertically aligned nematic indeed assume the observed shape. The parameter values required are compared with the experimental materials and conditions.
Second-harmonic generation from CuInSe/sub 2/ thin films: influence of the substrate-epilayer lattice mismatch

We investigate the second-order nonlinear optical (NLO) properties of tetragonal chalcopyrite-structure CuInSe/sub 2/ thin films using optical second-harmonic generation at a fundamental wavelength of 790 nm. An approximate doubling of the second-order optical nonlinearity of the CuInSe/sub 2/ thin films is achieved through changing the substrate from GaAs[001] to In/sub 0.29/Ga/sub 0.71/As[001], thereby reducing the lattice mismatch from 2.2% to 0.2%. This observation suggests that minimizing the lattice mismatch is a key requirement for the growth of high-quality NLO active chalcopyrite structure thin films and is in contrast to some other NLO active thin-film systems.
Journal of Quantitative Analysis in Sports Home Advantage in American College Football Games : A Multilevel Modelling Approach

This study examines home advantage in American college football games from a multilevel perspective. It quantifies the extent and significance of that home advantage and examines how it varies between BCS and non-BCS teams as well as analyzing the relationship between home advantage and team parity. Our results indicate that home advantage exists for most teams and conferences. It equates to a 6 point advantage for home teams and a 3-point disadvantage for away teams when controlling for team strength and other predictors. It concludes that after controlling for team ability, non-BCS teams possess a stronger home advantage than BCS teams. Such a result is likely related to the greater parity among BCS teams which leads to a “choking under pressure” effect for them in closely played games.
Comparative study of acceleration techniques for integrals and series in electromagnetic problems

Most of the electromagnetic problems can be reduced down to either integrating oscillatory integrals or summing up complex series. However, limits of the integrals and the series usually extend to infinity. In addition, they may be slowly convergent. Therefore, numerically efficient techniques for evaluating the integrals or for calculating the sum of infinite series have to be used to make the numerical solution feasible and attractive. In the literature, there are a wide range of applications of such methods to various EM problems. In this paper, our main aim is to critically examine the popular series transformation (acceleration) methods which are used in electromagnetic problems and compare them by numerical examples.
Characterization of a Surface Wave Driven Plasma Monopole Antenna

—This theoretical study examines the characteristics of a surface wave driven argon plasma monopole antenna with excitation power level up to 100 W and gas pressure of 0.4 mb using finite difference time domain method. Input impedance, radiation pattern, gain, efficiency and radar cross section of plasma antenna at different excitation power are presented here. The results show that variations of the excitation powers can be used for construction of a dynamically reconfigurable antenna. Since the plasma tube is one of the important factors which can affect the performance of the antenna, the input impedance and gain of plasma antenna was studied under different thicknesses and materials. The least thickness can cause a more efficient antenna while minimizing its bandwidth.
Sobrification and bicompletion of totally bounded quasi-uniform spaces

Abstract We observe that if is a compatible totally bounded quasi-uniformity on a T0-space (X,), then the bicompletion of (X, ) is a strongly sober, locally quasicompact space. It follows that the b-closure S of (X, ) in is homeomorphic to the sobrification of the space (X, ). We prove that S is equal to if and only if (X, ) is a core-compact space in which every ultrafilter has an irreducible convergence set and is the coarsest quasi-uniformity compatible with . If is the Pervin quasi-uniformity on X, then S is equal to if and only if X is hereditarily quasicompact, or equivalently, is the Pervin quasi-uniformity on .
Fabric Study of Granular Materials after Compaction

Numerous micromechanical models have been developed based on assemblies of spherical particles with certain fabric distributions. Most of these distributions are hypothetical, and only very few of them can be determined experimentally. This paper presents a study to provide some useful fabric information for granular material. The discrete element method is used to study the microscopic information for granular materials after compaction. Specimens with 520 identical ellipsoidal elements are generated and compressed under different conditions. Up to six different aspect ratios are used to study their effect on the compression process. Two different compression methods and five different microfrictions between particles are used. The fabric of the specimens after compaction, including the total number of contacts, the distribution of particle orientations, the distribution of branch vectors, the distribution of the length of branch vectors, and the spatial distribution of a similar length of branch vector, is presented. The relations between these fabrics and particle shape, microfriction, and the compression process are also developed.
How students learn statistics

Summary Research in the areas of psychology, statistical education, and mathematics education is reviewed and the results applied to the teaching of college-level statistics courses. The argument is made that statistics educators need to determine what it is they really want students to learn, to modify their teaching according to suggestions from the research literature, and to use assessment to determine if their teaching is effective and if students are developing statistical understanding and competence.
Using representations in geometry: a model of students’ cognitive and affective performance

Self-efficacy beliefs in mathematics, as a dimension of the affective domain, are related with students’ performance on solving tasks and mainly on overcoming cognitive obstacles. The present study investigated the interrelations of cognitive performance on geometry and young students’ self-efficacy beliefs about using representations for solving geometrical tasks. The emphasis was on confirming a theoretical model for the primary-school and secondary-school students and identifying the differences and similarities for the two ages. A quantitative study was developed and data were collected from 1086 students in Grades 5–8. Confirmatory factor analysis affirmed the existence of a coherent model of affective dimensions about the use of representations for understanding the geometrical concepts, which becomes more stable across the educational levels.
Vacancy in Silicon Revisited: Structure and Pressure Effects

The structure of the single vacancy in silicon, one of the most common point defects and an important mediator of atomic diffusion, is examined through extensive first principles calculations. We find a hitherto unexpected result, namely that there exist two distinct distortions associated with the vacancy with essentially identical formation energies at zero pressure. The two distortions are distinguished by their different relaxations, volumes of formation, and formation enthalpies. We discuss how, at finite pressure, one of the two distortions should become dominant, and suggest experimental tests of this effect. [S0031-9007(98)07002-1]
Numerical Modeling of a Concurrent PIT/PIV Experiment with TLC Particles in a Reservoir Model Subject to Periodic Thermal Forcing

The present investigation is concerned with the transient flow response of a reservoir model to periodic thermal forcing at water surface. A previously reported concurrent PIT/PIV experiment is numerically reproduced using a Computational Fluid Dynamics (CFD) code coupled with a Discrete Phase Model (DPM). Both qualitative and quantitative agreements are achieved between the present numerical simulation and the experiment. A parametric study is also carried out using the numerical model to determine the dependence of the flow response and its stability properties on the Grashof number.