Miracle-dz/UniFAR-FTUs huggingface dataset:
Drift mirror instability revisited, 1, Cold electron temperature limit

Linear theory of the drift-mirror instability in high-β plasma is reconsidered referring to basic principles for the two cases of a one- and a two-component ion plasma in presence of a cold electron background. In both cases the cold electrons serve to shortcut the parallel electric field component which imposes the condition of vanishing the field-aligned current. The corresponding low-frequency dispersion relation is derived in the fluid approximation as well as from kinetic theory including nonvanishing gradients in the density. The free energy of the unstable mode is taken from two sources: the pressure anisotropy and the spatial inhomogeneity of the plasma. The dispersion relation contains a correction which originates from the inclusion of the bending of the magnetic field that is caused by the reaction of the field to the total pressure force. It is shown that the mirror force substantially reduces the phase velocity which is in favour of instability since this requires phase velocities less than the drift speed. The direction of phase velocity becomes antiparallel to that of the pure density-gradient drift velocity. Even for a mirror-stable plasma an instability arises which is solely due to inhomogeneity. We analyze the transition to the classical mirror instability. Application to ring current (hot ring current ions plus cold plasmasphere ions) and magnetosheath (hot sheath ions only) conditions is presented and is in agreement with observational indication of the apparent stability of the pure mirror mode in the ring current.
Selection of the Ridge Parameter Using Mathematical Programming

Ridge regression solves multicollinearity problems by introducing a biasing parameter that is called ridge parameter; it shrinks the estimates and their standard errors in order to reach acceptable results. Selection of the ridge parameter was done using several subjective and objective techniques that are concerned with certain criteria. In this study, selection of the ridge parameter depends on other important statistical measures to reach a better value of the ridge parameter. The proposed ridge parameter selection technique depends on a mathematical programming model and the results are evaluated using a simulation study. The performance of the proposed method is good when the error variance is greater than or equal to one; the sample consists of 20 observations, the number of explanatory variables in the model is 2, and there is a very strong correlation between the two explanatory variables.
Lower hybrid current drive at ITER‐relevant high plasma densities

Recent experiments indicated that a further non‐inductive current, besides bootstrap, should be necessary for developing advanced scenario for ITER. The lower hybrid current drive (LHCD) should provide such tool, but its effectiveness was still not proved in operations with ITER‐relevant density of the plasma column periphery. Progress of the LH deposition modelling is presented, performed considering the wave physics of the edge, and different ITER‐relevant edge parameters. Operations with relatively high edge electron temperatures are expected to reduce the LH// spectral broadening and, consequently, enabling the LH power to propagate also in high density plasmas (// is the wavenumber componenent aligned to the confinement magnetic field). New results of FTU experiments are presented, performed by following the aforementioned modeling: they indicate that, for the first time, the LHCD conditions are established by operating at ITER‐relevant high edge densities.
The Rayleigh Scattering Cross-Sections of He, C, N and O

The Rayleigh scattering cross-sections of He, C, N and 0 have been computed by quantum defect method. Fairly good agreement has been obtained between the results of dipole length and dipole velocity formalisms. The wavelength independent part of the polarizabilities obtained in the calculation have been compared with the static polarizabilities given by others. At large wavelengths, the Rayleigh scattering cross-sections of He, C, N and 0 relative to H, have been found to be approximately in the ratio of 0.1 : 7.9 : 4.I : 1.4. The effect of wavelength dependent polarizabilities on Rayleigh scattering cross-sections has also been investigated. The importance of Rayleigh scattering vis-a-vis pure absorption has been discussed.
Evidence for Anomalous Lepton Production in e+ - e- Annihilation

We have found events of the form e++e−→e±+μ∓+missingenergy, in which no other charged particles or photons are detected. Most of these events are detected at or above a center-of-mass energy of 4 GeV. The missing-energy and missing-momentum spectra require that at least two additional particles be produced in each event. We have no conventional explanation for these events.
Physics and Engineering Design for Wendelstein VII-X

AbstractThe future experiment Wendelstein VII-X (W VII-X) is being developed at the Max-Planck-Institut fur Plasmaphysik. A Helical Advanced Stellarator (Helias) configuration has been chosen because of its confinement and stability properties. The goals of W VII-X are to continue the development of the modular stellarator, to demonstrate the reactor capability of this stellarator line, and to achieve quasi-steady-state operation in a temperature regime >5 keV. This temperature regime can be reached in W VII-X if neoclassical transport plus the anomalous transport found in W VII-A prevail. A heating power of 20 MW will be applied to reach the reactor-relevant parameter regime.The magnetic field in W VII-X has five field periods. Other basic data are as follows: major radius R0 = 6.5 m, magnetic induction B0 = 3 T, stored magnetic energy W ≈ 0.88 GJ, and average plasma radius a = 0.65 m. Superconducting coils are favored because of their steady-state field, but pulsed water-cooled copper coils are also bei.
On the Local Stability of Sunspot Equilibria under Adaptive Learning Rules

Abstract We examine local stability under learning of stationary Markov sunspot equilibria (SSEs) in a simple dynamic nonlinear model. Necessary and sufficient conditions for local convergence of a recursive learning algorithm to SSEs are shown to be given (generically) by expectational stability (E-stability) conditions. We distinguish between weak and strong E-stability, where the latter requires stability also with respect to overparametrizations of the sunspot solution. Economic applications are given based on the overlapping generations model. Journal of Economic Literature Classification Numbers: D84, E32, C62.
Neuroinflammatory syndromes in children

Purpose of review Neuropsychiatric symptoms due to paediatric neuroinflammatory diseases are increasingly recognized and reported. Psychiatrists are crucial in front-lines identification, diagnosis and care of individuals with disorders such as autoimmune encephalitis and management of long-term neurobehavioral sequelae. This review summarizes recent literature on autoimmune and post-infectious encephalitis, discusses special considerations in children with neurodevelopmental conditions and presents a paradigm for evaluation and management. Recent findings There is a growing body of evidence on neuropsychiatric symptom burdens of paediatric neuroinflammatory diseases. A particular development is the evolution of diagnostic and treatment guidelines for conditions such as autoimmune encephalitis, which take into account phenotypes of acute, short-term and long-term sequelae. Interest in inflammatory sequelae of viral illness, such as SARS-CoV-2, in children remains in early development. Summary Neuroimmunological disease data are constantly evolving. New recommendations exist for multiple common neuroimmunological disorders with behavioural, emotional, cognitive and neurological sequelae. Anti-NMDA receptor encephalitis now has well-recognized patterns of symptom semiology, diagnostic and treatment recommendations, and outcome patterns. Recognizing psychiatric symptoms heralding autoimmune brain disease and understanding neuropsychiatric sequelae are now a crucial skill set for paediatric psychiatrists. Exploration of inflammatory features of other diseases, such as genetic syndromes, is a burgeoning research area.
The Effect of a Multidimensional Home Rehabilitation Program for Post-Total Knee Arthroplasty Elderly Patients

Patients with total knee arthroplasty (TKA) experience pain, decreased muscle strength, and decreased knee function, resulting in increases in depression and decreased subjective well-being. A multidimensional home program may prevent these adverse events. The aim of this study was to test the effect of a home rehabilitation program that included education, exercise, aroma massage, and phone counseling for post-TKA patients. We used a randomized control group pretest/posttest design. Fifty-nine patients participated, with 29 in the experimental group and 30 in the control group. Pain, knee joint range of motion (ROM), quadriceps strength, depression, and subjective well-being were measured as outcome variables. Data were analyzed using repeated-measures analysis of variance and generalized estimating equations. The experimental group showed significant improvement in knee pain, active ROM, muscle strength, depression, and subjective well-being with no significant between-groups difference in passive ROM. The multidimensional home rehabilitation program can be an effective nursing intervention for physical and emotional recovery of patients with TKA.
Correlation of contact resistance with microstructure for Au/Ni/Al/Ti/AlGaN/GaN ohmic contacts using transmission electron microscopy

Ohmic contacts to AlGaN/GaN heterostructures which have low contact resistance and good surface morphology are required for the development of commercial high power, high frequency transistors in the GaN system. The development of such contacts would be helped by a better understanding of the effect of microstructure on electrical behavior, which is studied here. Au/Ni/Al/Ti/AlGaN/GaN ohmic contact structures were rapid thermal annealed in argon for 60 s at temperatures in the range 550–900 °C. The variation of contact resistance with anneal temperature was correlated with the phase distribution observed by transmission electron microscopy (TEM). A combination of TEM techniques was required to determine the resulting microstructure, including energy filtered TEM, high resolution electron microscopy and energy dispersive x-ray spectrum imaging. Contacts with the lowest resistance were formed after 700 °C annealing. Very little consumption of the 30 nm AlGaN layer was observed. An unidentified phase containing Al, Ti and Au is present at the interface in the samples with low specific contact resistance. The identification of the observed thin interfacial phases (including TiN and AlN) is discussed, along with the effects of oxidation and possible mechanisms of ohmic contact formation.
Accurate radiation and impedance characteristics of horn antennas-a moment-method model

A moment-method-model for horn analysis is presented. The generalized reflection matrix of the aperture is determined using the spectral Galerkin method. The reflection matrix is then combined with the generalized scattering matrix of the horn to yield the input return loss and the aperture fields of the horn. It is shown that the model can predict the radiation characteristics more accurately than the models commonly used in practice.
Pair Plasma Dominance in the 3C 279 Jet on Parsec Scales

We have investigated whether a pc-scale jet of 3C 279 is dominated by a normal plasma or an electronpositron plasma. By analyzing Very Long Baseline Interferometry data between 1983 and 1990, and utilizing the theory of synchrotron self-absorption, we have derived the lower limits for the proper electron number density. Comparing the lower limit with another independent constraint for the electron density that is deduced from the kinetic luminosity, we find that the core and components C3 and C4 are likely dominated by an electron-positron plasma.
On Long's hypothesis of no upstream influence in uniformly stratified or rotating flow

The weakly nonlinear, two-dimensional problem for the disturbance due to a slender obstacle in a uniformly stratified, Boussinesq fluid moving past the obstacle with constant basic horizontal velocity U, is considered up to second order in the amplitude ε of the disturbance. Analogous rotating problems are also treated. Particular attention is given to calculating explicitly the columnar-disturbance strengths upstream and downstream of the obstacle, both in the stratified and in the rotating problems, with a view to discussing the truth or otherwise of Long's hypothesis (LH). Whether or not columnar disturbances are found far upstream, violating LH, depends, interalia, on whether or not the flow is externally bounded by rigid horizontal planes (or by a tube or annulus, in the rotating problem), and on whether the problem is made determinate by means of an ‘inviscid transient’ formulation, or by means of a ‘viscous’ one. The inviscid, transient, bounded problem, for time-development of lee waves from a state of no initial disturbance, always exhibits columnar disturbances oforder ε2 somewhere in the fluid. They are generated, not near the obstacle, but in the ‘tails’ or transient terminal zones of the lee-wave trains. The columnar-disturbance strengths are largely independent of how the flow is set up from an initially undisturbed state. I n all but one instance the effect is non-zero far up-stream. The exception is the singly-subcritical stratified (or narrow-gap rotating) case, in which the excitation has modal structure sin(2z), the fluid region being 0 [les ] z [les ] π in this case the only columnar disturbance that can penetrate up-stream has structure sinz and so is not excited. A completely different result holds for ‘viscous’ formulations for unseparated, bounded régimes (with steady lee waves spatially attenuated by effects of small molecular diffusion). The strengths of all columnar disturbances, upstream and downstream, vanish in the limit of small diffusivity. In the inviscid, transient, unbounded problem, the upstream influence is, likewise, evanescent, being O(ε2t−2) as time t → ∞. The basic expansion in powers of ε will be invalid for times ∝ ε−1 or greater, because of resonant-interactive instability of the lee waves.
Steady Flow of Power Law Fluids across a Circular Cylinder

The momentum equations describing the steady cross-flow of power law fluids past an unconfined circular cylinder have been solved numerically using a semi-implicit finite volume method. The numerical results highlighting the roles of Reynolds number and power law index on the global and detailed flow characteristics have been presented over wide ranges of conditions as 5 ≤ Re ≤ 40 and 0.6 ≤ n ≤ 2. The shear-thinning behaviour (n 1) show the opposite behaviour. Furthermore, while the wake size shows non-monotonous variation with the power law index, but it does not seem to influence the values of drag coefficient. The stagnation pressure coefficient and drag coefficient also show a complex dependence on the power law index and Reynolds number. In addition, the pressure coefficient, vorticity and viscosity distributions on the surface of the cylinder have also been presented to gain further physical insights into the detailed flow kinematics.
Measurement of K shell absorption and fluorescence parameters for the elements Mo, Ag, Cd, In and Sn using a weak gamma source

K shell fluorescence parameters such as fluorescence yield, fluorescence cross section and absorption jump factor for pure elemental targets of Mo, Ag, Cd, In and Sn have been determined by adopting a 2π geometrical configuration. The K x-ray photons are excited in the target using 123.6 keV gamma rays from a weak 57Co source, and detected with a GMX 10P HPGe detector coupled to an 8K multichannel analyser. Measured values of these parameters have been compared with theoretical and others' experimental values.
Maurey's Extension Theorem and Grothendieck's Problème Des Topologies

Relating geometric notions like type and cotype from local Banach space theory with some important topological invariants for Fréchet spaces (for example the density condition), we prove a version of Maurey's celebrated extension theorem for the category of Fréchet spaces, and apply it to Grothendieck's problème des topologies.
A CONSTRUCTIVE DEFINITION OF DIRICHLET PRIORS

Abstract : The parameter in a Bayesian nonparametric problem is the unknown distribution P of the observation X. A Bayesian uses a prior distribution for P, and after observing X, solves the statistical inference problem by using the posterior distribution of P, which is the conditional distribution of P given X. For Bayesian nonparametrics to be successful one needs a large class of priors for which posterior distributions can be easily calculated. Unless X takes values in a finite space, the unknown distribution P varies in an infinite dimensional space. Thus one has to talk about measures in a complicated space like the space of all probability measures on a large space. This has always required a more careful attention to the attendant measure theoretic problems. A class of priors known as Dirichlet measures have been used for the distribution of a random variable X when it takes values in R sub K.
The mean and variance of diffuse field correlations in finite bodies

A model consisting of uniformly distributed concentrated transient sources in closed reverberant systems is used to construct predictions for the diffuse field correlation function and its variance. Such correlations are useful for passive imaging. It is found that the variance is small compared with the square of the mean if estimates are based on a sufficient number of sources, and if a sufficiently long data record is taken from each source. Requirements are predicted to be most onerous at high frequency. Laboratory measurements support this theory. They furthermore indicate that the fidelity of the passively obtained correlation function to an actively obtained waveform depends, not only on having sufficient passive data, but also on an informed compensation for source spectrum and receiver characteristics. It is anticipated that these arguments will be relevant to convergence rates and fidelity for passive imaging in open systems such as are found in seismology and ocean acoustics.
A tool to calculate the linewidth of complicated semiconductor lasers

A theory of the low-frequency phase fluctuations in the output of a semiconductor laser due to spontaneous emission is developed. The theory can be used as a tool to numerically calculate the linewidth of complicated laser structures, e.g., by use of the transfer matrix formulation. The results for the single Fabry-Perot laser are shown to be in exact agreement with the most accurate treatments published so far. Results are then presented for both DFB and F-P lasers with external optical feedback showing how the linewidth varies with the threshold gain, with the coupling coefficient, and with the external feedback conditions.
Large‐eddy simulation of a compressible free jet flow on unstructured elements

Purpose – The purpose of this paper is to investigate a large‐eddy simulation, using low order numerical discretization and upwinding schemes on unstructured grids, for a turbulent free jet at Mach number 0.95. The accuracy and stability performance is discussed for the finite element/volume upwinding numerical code used.Design/methodology/approach – This code is equipped with a self‐adaptive upwinding method which has been previously developed to reduce the numerical dissipation of applied low order flux calculation on unstructured elements using Roe's scheme. Herein, this method is used to numerically investigate a high Reynolds, compressible turbulent free jet and compare the results with a recently published set of experimental data. The effect of grid size is also investigated. A reasonable good agreement with the experimental measurements is obtained.Findings – Based on the results, it is concluded that the developed self‐adaptive upwinding scheme provides a considerably better emulation of the flow.
Zoom-based super-resolution reconstruction approach using prior total variation

We present a robust and efficient approach for zoom-based super-resolution (SR) reconstruction problems. We employ the total variation (TV) of the desired image priori in the maximum a-posteriori estimation. An efficient algorithm based on iterative methods and preconditioning techniques is employed to solve the resulting variational problem. To suit the proposed algorithm for realistic imaging situations, a registration method is presented to simultaneously solve the zooming factors, image center shifts, and photometric parameters. Experimental results show that the proposed TV-based algorithm performs quite well in terms of both quantitative measurements and visual evaluation. We also demonstrate that the proposed algorithm is robust for SR image inpainting, where some pixels are missed in the SR reconstruction model.
Growth and characterization of high current density, high-speed InAs/AlSb resonant tunneling diodes

High quality resonant tunneling diodes have been fabricated from the InAs/AlSb material system (InAs quantum well and cladding layers, AlSb barriers) on (100)GaAs substrates. A diode with a 6.4‐nm‐thick InAs quantum well and 1.5‐nm‐thick AlSb barriers yielded a room‐temperature peak current density of 3.7×105 A cm−2 and peak‐to‐valley current ratio of 3.2. This corresponds to an available current density of 2.6×105 A cm−2, which is comparable to that of the best In0.53Ga0. 47As/AlAs diodes grown on lattice‐matched substrates and is three times higher than that of the best GaAs/AlAs diode reported to date. These results were obtained in spite of a 7.2% lattice mismatch between the InAs epilayers and the GaAs substrates, which leads to a measured threading dislocation density of roughly 109 cm−2. The experimental peak voltage and current density are in good agreement with theoretical calculations based on a stationary‐state transport model with a two‐band envelope function approximation.
Observations of the Origin and Distribution of Ice in Cold, Warm, and Occluded Frontal Systems during the DIAMET Campaign

AbstractThree case studies in frontal clouds from the Diabatic Influences on Mesoscale Structures in Extratropical Storms (DIAMET) project are described to understand the microphysical development of the mixed phase regions of these clouds. The cases are a kata-type cold front, a wintertime warm front, and a summertime occluded frontal system. The clouds were observed by radar, satellite, and in situ microphysics measurements from the U.K. Facility for Airborne Atmospheric Measurements (FAAM) research aircraft. The kata cold front cloud was shallow with a cloud-top temperature of approximately −13°C. Cloud-top heterogeneous ice nucleation was found to be consistent with predictions by a primary ice nucleation scheme. The other case studies had high cloud tops (< −40°C) and despite no direct cloud-top measurements in these regions, homogeneous ice nucleation would be expected. The maximum ice crystal concentrations and ice water contents in all clouds were observed at temperatures around −5°C. Graupel was .