Miracle-dz/UniFAR-FTUs huggingface dataset:
The electromagnetic gauge in the variational formulation of kinetic and other theories

This paper investigates the implications and consequences of choosing special gauges or gauge-invariant or non-gauge-invariant approximations in the action integral for the variational formulation of theories involving electromagnetic fields. After some interesting special gauges are considered, it is shown that non-gauge-invariant approximations always lead to inconsistent Euler–Lagrange equations. As a concrete example, Maxwell–Vlasov theory is investigated. The special non-gauge-invariant case considered, which is sometimes used in the literature, is obtained by replacing the contribution of the electric field to the Maxwell part of the Lagrangian density by the contribution of the gradient of the scalar potential alone. The detailed investigation concerns the local energy conservation law, and it is shown that the law thus derived is incorrect since it contains non-physical, spurious terms. An improvement of this situation can be obtained by the introduction of a Lagrange multiplier in the non-gauge-invariant theories in order to avoid inconsistencies in the local charge conservation law. The results are also valid for drift-kinetic and gyrokinetic theories, and for other theories, e.g. two-fluid theories.
Type I supernovae. I. Analytic solutions for the early part of the light curve

Analytic solutions for light curves, effective temperatures, and broad-band colors of Type I supernovae are presented. The method is generalized to include effects of finite (large) initial radius and increasing transparency to . gamma. -rays and to thermal photons. A theoretical construct, the ''blackbody supernova,'' is introduced. Many observed features of Type I supernovae are shown to be reproduced by the theory. For a given composition it is shown that the homogeneity of spectral evolution is a necessary consequence of the thermonuclear model but only a possible consequence of the gravitational collapse model. Comparison with 1970j and 1972e suggests a variation in explosion energy of a factor of 2, and a corresponding variation in intrinsic luminosity at maximum light; such variation can be identified in a distance-independent way.
Comparison of optical and tactile layer thickness measurements of polymers and metals on silicon or SiO2

The thickness measurement of transparent layers with optical techniques is very problematic. The observed deviations can easily reach 100% of the layer thickness to be measured. In order to analyse these deviations, tactile reference measurements have been developed. The proposed method is based on contact mode measurements with low contact pressure. With stylus instruments, this can be realized either by using the recommended tip radius of 2 µm and very small probing forces in the micronewton range (and low scanning speeds of 50 µm s−1) or by using the recommended probing force of 750 µN, but a large probing tip radius. Three metal layers on silicon or silicon dioxide and two polymer resist materials on a thin chromium adhesive layer on silicon are used as artefacts. The comparison of the optical measurements with the tactile reference values disclosed deviations of the optical measurements of up to 195% of the layer thickness. Layer thicknesses were between 200 nm and 4 µm. This paper analyses the deviations of two white light interference microscopes, one phase shift interference microscope, one confocal microscope, one autofocus sensor, a chromatic sensor, an interferometric film thickness sensor and one spectroscopic ellipsometer. Simple and well-known expressions for the description of the observed deviations are presented and discussed. The order of magnitude of the observed deviations can be described well by these correction formulas but further investigations are necessary in order to better understand the systematic deviations of optical surface measuring instruments on non-cooperating surfaces.
Scattering By a Composite and Anisotropic Circular Cylindrical Structure: Exact Solution

ABSTRACT Exact analytical solution for the two-dimensional problem of electromagnetic (EM) scattering by a composite and anisotropic circular cylindrical structure is presented in this paper. The scatterer consists of a metallic cylinder coated by a lossy anisotropic layer and by an impedance sheet. In the anisotropic layer both permittivity and permeability tensors, when referred to principal axes (ρ,Φ,z), are biaxial and diagonal. The impedance sheet is also anisotropic and is characterized by a surface admittance tensor . The primary EM source is an arbitrarily polarized plane wave, normally incident on the cylinder. Closed form expressions are derived for the EM fields in the biaxial layer, induced currents on the conducting core and on the impedance sheet, and also the scattered fields in the exterior region. The axial components of the EM fields are expressed in terms of Fourier series whose terms are products of radial eigenfunctions and azimutal harmonic functions. It is shown that, in the anisotr.
A Bayesian model for estimating the malaria transition probabilities considering individuals lost to follow-up

It is known that patients may cease participating in a longitudinal study and become lost to follow-up. The objective of this article is to present a Bayesian model to estimate the malaria transition probabilities considering individuals lost to follow-up. We consider a homogeneous population, and it is assumed that the considered period of time is small enough to avoid two or more transitions from one state of health to another. The proposed model is based on a Gibbs sampling algorithm that uses information of lost to follow-up at the end of the longitudinal study. To simulate the unknown number of individuals with positive and negative states of malaria at the end of the study and lost to follow-up, two latent variables were introduced in the model. We used a real data set and a simulated data to illustrate the application of the methodology. The proposed model showed a good fit to these data sets, and the algorithm did not show problems of convergence or lack of identifiability. We conclude that the proposed model is a good alternative to estimate probabilities of transitions from one state of health to the other in studies with low adherence to follow-up.
Effect of membrane bending stiffness on the axisymmetric deformation of capsules in uniaxial extensional flow

The effect of interface bending stiffness on the axisymmetric deformation of liquid capsules enclosed by elastic membranes subject to uniaxial extensional flow is considered. Flow-induced deformation causes the development of membrane in-plane elastic tensions and bending moments due to the noninfinitesimal thickness of the membrane or to a preferred equilibrium configuration of an interfacial molecular network, accompanied by transverse shear tensions. The elastic tensions are related to the surface deformation by means of Mooney’s linear constitutive law for thin elastic sheets, and the bending moments are related to the membrane resting shape and to the instantaneous principal curvatures by means of constitutive equations. Interfacial force and torque balances are used to relate the jump in hydrodynamic traction across the interface to the elastic tensions and bending moments. A numerical procedure is implemented for simulating the capsule deformation in uniaxial extensional Stokes flow based on a boun.
A Novel Polarized Elastic Scatter Detection Method of Aerosol Particle Velocimetry with Reduced Errors Due to Coincidence and Phantom Particles

This article describes a novel polarized elastic scattering method to measure flow velocities of aerosol particles. Velocities of individual aerosol particles of mixed size, and composition have been determined from time differences between scattered light pulses as they move between two parallel laser beams separated by a fixed distance, known as a time-of-flight method. By using two orthogonally polarized laser beams, the detected light pulses can be assigned to each beam by simultaneously determining their respective depolarization ratio. This implementation of time-of-flight velocimetry provides a mechanically robust distance between the two beams, which reduces error in the measurement and improves both its precision and accuracy, but more importantly, the use of the polarization features of the scattered light reduces errors due to particle coincidence and phantom particles caused by confusion of start and stop timing pulses. This approach was developed and demonstrated in an application to provide effective timing for subsequent selective actions on individual particles downstream such as: further diagnostic measurement, electrical charging and capture. These downstream actions require accurately predicted individual particle trajectories. Copyright 2013 American Association for Aerosol Research
In-situ ultrasonic thermometry of semiconductor wafers

We report a temperature measurement technique based on the temperature dependence of acoustic wave velocity in silicon wafers. The zeroth order antisymmetric Lamb wave is excited in the wafer using the quartz pins which support the wafer during processing. Extensional waves are generated in the quartz pin by a PZT-SH transducer and the acoustic energy is coupled to the Lamb wave at the contact between the sharpened end of the pin and the wafer surface. The detection is done by a similarly modified quartz pin. By measuring the time of flight of the Lamb wave in the wafer between the two pins, we have monitored the wafer temperature in-situ in the 20-1000dC range with p1 accuracy. With 8 spring loaded pins placed on a circular array around the wafer, 28 different measurements are made giving information about different regions. Using tomographic reconstruction techniques, the spatial temperature distribution with a 2 cm pixel size is then calculated. Excellent agreement is observed between the readings of thermocouples attached to the wafer, and calculated values for ultrasonic tomography
Disclosure of intimate partner violence experiences during COVID-19: patient-provider communication in a Southern United States emergency department

ABSTRACT Using the lens of Communication Privacy Management (CPM) theory, this article examines communication between health care providers in the southern United States emergency department (ED) and patients who have experienced IPV. We qualitatively examine communicative challenges that COVID-19 protocols have created, as well as routine difficulties that occur when communicating with survivors of violence. The participants described challenges including: (1) Feeling uncertainty, (2) Encountering patient resistance, (3) Managing apathy and frustration, and (4) Navigating time pressure. Furthermore, the providers explained how COVID-19 compounded those challenges through: (1) Minimizing contact, (2) Losing nonverbal behavior, (3) Encountering limited resources, and (4) Facing visitor complications. This article extends CPM theory by exploring disclosure challenges related to IPV in health care settings during the COVID-19 pandemic including permeability, linkages, and privacy rules. It offers practical suggestions for increasing patient disclosure of IPV experiences.
Practical issues of retrieving isolated attosecond pulses

The attosecond streaking technique is used for the characterization of isolated extreme ultraviolet (XUV) attosecond pulses. This type of measurement suffers from low photoelectron counts in the streaked spectrogram, and is thus susceptible to shot noise. For the retrieval of few- or mono-cycle attosecond pulses, high-intensity streaking laser fields are required, which cause the energy spectrum of above-threshold ionized (ATI) electrons to overlap with that of the streaked photoelectrons. It is found by using the principal component generalized projections algorithm that the XUV attosecond pulse can accurately be retrieved for simulated and experimental spectrograms with a peak value of 50 or more photoelectron counts. Also, the minimum streaking intensity is found to be more than 50 times smaller than that required by the classical streaking camera for retrieval of pulses with a spectral bandwidth supporting 90 as transform-limited pulse durations. Furthermore, spatial variation of the streaking laser intensity, collection angle of streaked electrons and time delay jitter between the XUV pulse and streaking field can degrade the quality of the streaked spectrogram. We find that even when the XUV and streaking laser focal spots are comparable in size, the streaking electrons are collected from a 4π solid angle, or the delay fluctuates by more than the attosecond pulse duration, the attosecond pulses can still be accurately retrieved. In order to explain the insusceptibility of the streaked spectrogram to these factors, the linearity of the streaked spectrogram with respect to the streaking field is derived under the saddle point approximation.
Electromagnetic induction in terms of the Maxwell force instead of magnetic flux

The conventional treatment of induced EMFs in terms of magnetic flux leads to problems with the concepts of ‘flux-cutting’ and ‘flux-linking’ which have attracted much discussion and controversy, particularly when applied to devices with moving parts. Maxwell's own ‘general equations’ tend to be ignored. They did not include the ‘Maxwell’ field equation relating induced E fields to changes in the flux density, B , but developed an alternative view based on the magnetic vector-potential A . The practical role of A in the computation of EMFs and inductances suggests that it has corresponding conceptual advantages, including the relative simplicity of the A field of a current element. B is viewed as a symbol for the differential of A , thus reversing their customary roles, and removing the difficulties caused by the conventional treatment. It is shown that the use of A to describe the magnetic effects of the source currents helps to provide a clearer view of induction, and resolve the various problems and apparent anomalies. The relativistic relationship between the magnetic and electric fields is described most simply in terms of the potentials, and answers the much-debated question of the meaning of motion when applied to a uniform B field.
Role of Te/Ti and ∇vtor in ion heat transport of ASDEX Upgrade H-mode plasmas

Experiments in H-mode plasmas have shown that both heat and particle transport are sensitive to the ratio between electron and ion temperature (Te/Ti). While decreasing Te/Ti is beneficial for confinement, an increased electron heating in these so called ‘hot ion plasmas’ deteriorates the confinement. H-mode plasmas with low Te/Ti are often accompanied by high toroidal rotation velocity (vϕ). Its gradient (∇vϕ) can destabilize the ion temperature gradient mode (ITG) through its parallel component in the parallel velocity shear, but it has also stabilizing effects since it produces an E × B shearing rate (ωE × B). In this paper, the effects of electron heating on the ion heat transport is investigated in H-mode plasmas heated by neutral beam injection (NBI) and electron cyclotron heating (ECH). In particular, the correlation on Te/Ti and ∇vϕ is studied and compared with calculations made with GLF23 and GS2. Experimentally it is shown that the normalized gradient length of the ions ( ) is correlated with both Te/Ti and ∇vϕ: peaked ion temperature profiles are only obtained with low Te/Ti and high ∇vϕ, and vice-versa. When ECH is added, both ion heat and momentum transport are enhanced, leading to a drop of both the Ti and vϕ profiles. The effective growth rate γeff = γ−ωE × B is calculated, with the mode growth rate γ determined with GS2 and ωE × B with GLF23. The ion transport is enhanced due to the decrease of the ITG threshold with increasing Te/Ti. Comparison of the dependence of on Te/Ti and ∇vϕ between experiments and modelling indicates that the deterioration of confinement cannot be explained by the changes in only Te/Ti or ∇vϕ, but by the combined effects of both parameters. The changes in Te/Ti act directly on the ITG threshold, while the ones in ∇vϕ modify the ωE × B shearing rate leading to changes in the effective threshold.
A high-speed variable-temperature ultrahigh vacuum scanning tunneling microscope

An ultrahigh vacuum scanning tunneling microscopy (STM) system capable of collecting constant-current STM images at rates exceeding 1 image/s at temperatures up to 900 K was designed, built, and tested. The microscope uses an inchworm to push a scanner assembly through a quartz tube towards the sample. When the scanner is within tunneling range of the surface, the inchworm is decoupled from the scanner, resulting in a small, rigid mechanical loop with a high resonant frequency. The cylindrical symmetry and the use of low thermal expansion materials reduces image distortion due to thermal drift. An analog proportional-integral controller with tilt correction is used to maintain a constant tunnel current. A personal computer running Microsoft WINDOWS ’95 is used to control all other instrument functions, as well as for data acquisition, manipulation, and storage. Problems associated with the non real time nature of the operating system were overcome by collecting the STM images within a virtual device drive.
An adaptive covariance inflation error correction algorithm for ensemble filters

ABSTRACT Ensemble filter methods for combining model prior estimates with observations of a system to produce improved posterior estimates of the system state are nowbeing applied to a wide range of problems both in and out of the geophysics community. Basic implementations of ensemble filters are simple to develop even without any data assimilation expertise. However, obtaining good performance using small ensembles and/or models with significant amounts of error can be more challenging.Anumber of adjunct algorithms have been developed to ameliorate errors in ensemble filters. The most common are covariance inflation and localization which have been used in many applications of ensemble filters. Inflation algorithms modify the prior ensemble estimates of the state variance to reduce filter error and avoid filter divergence. These adjunct algorithms can require considerable tuning for good performance, which can entail significant expense. A hierarchical Bayesian approach is used to develop an adaptive covariance inflation algorithm for use with ensemble filters. This adaptive error correction algorithm uses the same observations that are used to adjust the ensemble filter estimate of the state to estimate appropriate values of covariance inflation. Results are shown for several low-order model examples and the algorithm produces results that are comparable with the best tuned inflation values, even for small ensembles in the presence of very large model error.
Copulas and Their Applications

Copulas have recently been of great interest to statisticians as well as financial econometricians since they give a promising, flexible tool for understanding dependence among random variables, and for modeling and simulating nonnormal multivariate data. In its simplest form, a d-dimensional copula function (or simply d-copula) is a d-dimensional distribution function with all univariate marginals being U(0, 1) distribution. The usefulness of copulas comes from Sklar's theorem, which states that any d-dimensional distribution function F can be represented as
On the average dynamical behaviour of stochastic population models

Abstract The dynamics of highly populated biological systems is often described in terms of ordinary differential equations. The trajectory produced by these equations is continuous and deterministic, and represents the limit behaviour as the system size tends to infinity. Because most biological systems are discrete, stochastic and finite, important phenomena, as oscillations, can be passed over by the limit behaviour. The computation of expected values on the associated embedded Markov process allows one to average functions of interest without resorting to the deterministic limit. In particular, one can average distances and angles with respect to a given reference point. This leads to a description of the process in polar coordinates that determines the dynamical system behaviour around the reference point.
Fractional Fourier Law with Three-Phase Lag of Thermoelasticity

In this work, a new mathematical model of heat conduction for an isotropic generalized thermoelasticity with a three-phase lag is derived using the methodology of fractional calculus. Some theorems of generalized thermoelasticity follow as limited cases. This model is applied to thermoelastic interaction due to periodically varying heat source. Some comparisons are shown in the figures to estimate the effects of the fractional order parameter on all the studied fields.
Spatial Distribution of Photocurrent in Si Stripes under Tilted Illumination Measured by Multimode Scanning Probe Microscopy

Spatial distribution of photocurrent in Si stripes of 50–1000 nm in width were investigated as a function of optical excitation wavelength by multimode scanning probe microscopy (MSPM). Inhomogeneous distribution of the MSPM photocurrent in the Si stripe interior was attributed to the light intensity profile. A model that included light absorption depth profile and the probe-induced band-bending region reproduced the photocurrent profile for tilted illumination of the stripes. An effective spatial resolution of ∼10 nm was deduced from the photocurrent measurements with multimode SPM in the constant-force mode.
A Unified Determinant-Preserving Formulation for Compressible/Incompressible Finite Viscoelasticity.

This paper presents a formulation alongside a numerical solution algorithm to describe the mechanical response of bodies made of a large class of viscoelastic materials undergoing arbitrary quasistatic finite deformations. With the objective of having a unified formulation that applies to a wide range of highly compressible, nearly incompressible, and fully incompressible soft organic materials in a numerically tractable manner, the viscoelasticity is described within a Lagrangian setting by a two-potential mixed formulation. In this formulation, the deformation field, a pressure field that ensues from a Legendre transform, and an internal variable of state Fv that describes the viscous part of the deformation are the independent fields. Consistent with the experimental evidence that viscous deformation is a volume-preserving process, the internal variable Fv is required to satisfy the constraint det Fv=1. To solve the resulting initial-boundary-value problem, a numerical solution algorithm is proposed that is based on a finite-element (FE) discretization of space and a finite-difference discretization of time. Specifically, a Variational Multiscale FE method is employed that allows for an arbitrary combination of shape functions for the deformation and pressure fields. To deal with the challenging non-convex constraint det Fv=1, a new time integration scheme is introduced that allows to convert any explicit or implicit scheme of choice into a stable scheme that preserves the constraint det Fv=1 identically. A series of test cases is presented that showcase the capabilities of the proposed formulation.