Miracle-dz/UniFAR-FTUs huggingface dataset:
Calculation and measurement of the time-of-flight spread in a hemispherical electron energy analyzer

We have determined the transit time distribution of electrons passing a high resolution hemispherical energy analyzer. Comparison of our measured results with analytical expressions reveals that differing transit times between electrons of equal kinetic energy mainly build up on the Kepler-type orbits on which the electrons travel through the hemispheres. To facilitate the measurements, we have installed a position sensitive electron detector capable of single event detection into our spectrometer. This device is based on a delay-line anode. We briefly report on the energy resolution achieved in comparison with a slower readout system via a fluorescent screen. The transit time distribution is important in coincidence experiments, where electrons detected in the hemispherical analyzer are to be related to events in other detectors. We discuss the feasibility of electron–electron coincidence experiments using a hemispherical detector plus a time-of-flight drift tube for energy discrimination of an electron pair.
AlGaN/GaN high electron mobility field effect transistors with low 1/f noise

Low-frequency noise in the frequency region of 20 Hz to 20 kHz is investigated in AlGaN/GaN high electron mobility transistors (HEMTs) grown on SiC substrates. The noise spectra have the form of the 1/f (flicker) noise. The measured Hooge parameter is as low as 0.0001. This value is comparable with Hooge parameter values for commercial GaAs field effect transistors and approximately two orders of magnitude smaller than Hooge parameter value measured for AlGaN/GaN heterostructures grown on sapphire. The level of noise depends on the gate leakage current; the noise is much higher in devices with a high gate leakage current. The small measured values of the Hooge parameter are related to a smaller leakage current and to a better material quality of the devices on SiC substrates and to a high electron sheet density. The low levels of the 1/f noise in the AlGaN/GaN HEMTs on SiC substrates make them suitable for applications in communication systems.
The radius dependence of velocity dispersion in spiral galaxies

The analytical model discussed in two previous papers is used to solve for the radial profile of the radial velocity dispersion on the plane of symmetry of an old galactic disc population. For a realistic total mass distribution consistent with an almost flat rotation curve and an exponential density profile, it is found that for relatively small radii a constant-anisotropy model provides a reasonable approximation to the solution, while for large R the solution is consistent with an approximately constant Toomre-Q profile, as suggested theoretically by Toomre (1964, ApJ, 139) and numerically by Sellwood & Carlberg (1984, ApJ, 292). Possible applications of this result are discussed
Vortex shedding and lock-on of a circular cylinder in oscillatory flow

An experimental study has been made of a circular cylinder in steady and oscillatory flow with non-zero mean velocity up to a Reynolds number of 40000. The results for the stationary cylinder are in close agreement with previously published data. Skin-friction measurements revealed the amplitude of fluctuation of the boundary layer for different angular locations. It has been universally accepted that bluff bodies shed vortices at their natural frequency of shedding (Strouhal frequency), or, when synchronized with an external unsteadiness, at the frequency of the disturbance or half of it, depending of the direction of the unsteadiness. Our findings, instead, indicate that the shedding frequency may vary smoothly with the driving frequency before locking on its subharmonic. Moreover, the present results indicate that, at the lowest frequency limit of lock-on, vortices are shed simultaneously on both sides of the model. A more traditional alternate pattern of vortex shedding is then recovered at higher driving frequencies.
Numerical simulation of meso‐gamma scale features of föhn at ground level in the Rhine valley

This paper examines the impact of a mesoscale analysis (2.5 km grid distance) on the simulation of the meso‐gamma scale aspects of föhn in the Rhine Valley. The föhn event, documented during IOP15 (5 November 1999) of the Mesoscale Alpine Programme, was standard in terms of intensity and was characterized by an important temporal variability. Many instruments operating in the Rhine valley target area are used to validate the simulation, in particular the airborne nadir‐pointing lidar LEANDRE 2 (flown over the lower Rhine valley) as well as a wind profiler and a radio accoustic sounding system collocated in Rankweil, Austria. The large observational dataset acquired during the IOP allowed documentation of the entire föhn life cycle. For most of the IOP, a cold pool remained near the ground in the lower northern part of the valley. The non‐hydrostatic model Meso‐NH, used in a grid‐nesting configuration with two nested models and initialized with a mesoscale analysis, allowed us to simulate realistically the location and depth of the cold pool. The relationship between the föhn intensity and the large‐scale environment is also examined. The flow regime is a ‘flow around’ the Alps. The variability of this flow at the western tip of the Alps could explain some of the temporal changes observed at low level in the Rhine valley. Copyright © 2005 Royal Meteorological Society
A comparison of semi-lagrangian and Eulerian polar climate simulations

Abstract At the modest vertical resolutions typical of climate models, simulations produced by models based on semi-Lagrangian approximations tend to develop a colder tropical tropopause than matching simulations from models with Eulerian approximations, all other components of the model being the same. The authors examine the source of this relative cold bias in the context of the NCAR CCM3 and show that it is primarily due to insufficient vertical resolution in the standard 18-level model, which has 3-km spacing near the tropopause. The difference is first diagnosed with the Held and Suarez idealized forcing to eliminate the complex radiative–convective feedback that affects the tropopause formation in the complete model. In the Held and Suarez case, the tropical simulations converge as the vertical grid layers are halved to produce 36 layers and halved again to produce 72 layers. The semi-Lagrangian approximations require extra resolution above the original 18 to capture the converged tropical tropopau.
Nonlinear analysis of shock–vortex interaction: Mach stem formation

Abstract Shock–vortex interaction is analysed for strong gaseous shock waves and a ratio of specific heats close to unity. A nonlinear wave equation for the wrinkles of the shock front is obtained for weak vortices. The solution breaks down after a finite time and the slope of the front develops jump discontinuities, indicating the formation of Mach stems. Shock–turbulence interactions are also briefly discussed.
Antibacterial, Antioxidant, and in silico NADPH Oxidase Inhibition Studies of Essential Oils of Lavandula dentata against Foodborne Pathogens

Food is always subjected to microbial infection and lipid peroxidation, which frequently leads to serious food intoxications. In the present study, essential oils (EOs) extracted from Lavandula dentata Moroccan species and its major component (linalool) were chemically characterized and their antioxidant potential and antibacterial properties against foodborne pathogenic bacteria were examined. EOs phytochemical profile was carried out using gas chromatography-mass spectrometry analysis (GC-MS). The antioxidant potential was evaluated, in vitro, by use of the β-carotene discoloration assay and in silico vs. NADPH oxidase enzymatic complex as an antioxidant marker. The antibacterial proprieties were assessed by use of minimal inhibitory concentration (MIC) and disc diffusion methods, against Gram (−) bacteria (Pseudomonas aeruginosa, Salmonella enterica, and Escherichia coli) and Gram (+) bacteria (Bacillus subtilis and Staphylococcus aureus). Linalool (49.71%) was the major component among the eighteen components identified in Lavandula dentate EO, followed by camphor (14.36%) and borneol (8.21%). The studied EO and linalool compounds showed important antioxidant activity through the β-carotene discoloration test with IC50 values of 35.72 ± 1.21 mg/mL and 30.32 ± 1.23 mg/mL, respectively. Among all the analyzed compounds of lavender EOs, thymol, carvacrol, and α-terpineol were the most active compounds against NADPH oxidase with a glide score of −6.483, −6.17, and −4.728 kcal/mol, respectively. 2D and 3D views showed the formation of hydrogen bonds between the most active compounds and the active site of NADPH oxidase. The antibacterial data showed a significant activity of Lavandula dentata essences against tested foodborne pathogenic bacteria, especially against S. aureus and B. subtilis. Linalool proved active toward the same bacteria and had closer activity to that of lavender essential oil. In light of the obtained findings, the essential oil of Lavandula dentata Moroccan species can be used in the packaging sector as a promising natural food conservative to limit lipid oxidation and treat foodborne infections.
Warped-average template technique to track on a cycle-by-cycle basis the cardiac filling phases on left ventricular volume

The dynamic time warping approach is utilised to obtain a template from the left ventricular volume signal. The technique, by performing shrinking and enlarging of the temporal axes of two waveforms, indicates the best non-linear alignment between them. In this application this technique is used to track on a cycle-by-cycle basis the diastasis onset and offset thus allowing one to reliably measure temporal sub-intervals of the filling period.
Inference for two‐stage adaptive treatment strategies using mixture distributions

Summary. Treatment of complex diseases such as cancer, leukaemia, acquired immune deficiency syndrome and depression usually follows complex treatment regimes consisting of time varying multiple courses of the same or different treatments. The goal is to achieve the largest overall benefit defined by a common end point such as survival. Adaptive treatment strategy refers to a sequence of treatments that are applied at different stages of therapy based on the individual's history of covariates and intermediate responses to the earlier treatments. However, in many cases treatment assignment depends only on intermediate response and prior treatments. Clinical trials are often designed to compare two or more adaptive treatment strategies. A common approach that is used in these trials is sequential randomization. Patients are randomized on entry into available first‐stage treatments and then on the basis of the response to the initial treatments are randomized to second‐stage treatments, and so on. The analysis often ignores this feature of randomization and frequently conducts separate analysis for each stage. Recent literature suggested several semiparametric and Bayesian methods for inference related to adaptive treatment strategies from sequentially randomized trials. We develop a parametric approach using mixture distributions to model the survival times under different adaptive treatment strategies. We show that the estimators proposed are asymptotically unbiased and can be easily implemented by using existing routines in statistical software packages.
The solar origin of long‐term variations of the interplanetary magnetic field strength

Spacecraft measurements over the past two sunspot cycles have shown that the average strength of the interplanetary magnetic field (IMF) undergoes surprisingly modest long-term variation, unlike the total magnetic flux observed on the Sun. Our attempt to model the IMF during sunspot cycle 21, based on a current-free extrapolation of the observed photospheric field out to a fixed source surface where the field lines become radial, yields calculated IMF intensities which vary by an order of magnitude and which are far too low near sunspot minimum. We obtain much better agreement with a model containing both heliospheric sheet currents, which deflect polar flux toward the ecliptic, and volume currents, which maintain a residual latitudinal gradient in the IMF intensity. In order to match the observed IMF intensity levels, however, the measured photospheric fields had to be scaled up by approximately a factor of 2. Our composite model has the following main consequences: (1) The source of the radial component of the IMF may be represented to a first approximation by the dipole component of the photospheric field. (2) The radial IMF intensity is strongest in the direction of the dipole axis, which is aligned with the Sun's rotation axis near sunspot minimum but tilts toward the ecliptic near sunspot maximum. (3) The average strength of the photospheric field above latitude 55° is of order 10 G around sunspot minimum.
Kostant’s problem and parabolic subgroups

This thesis consists of a summary and three papers, concerning some aspects of representation theory for complex finite dimensional semi-simple Lie algebras with focus on the BGG-category O.Paper I is motivated by the many useful properties of functors on category O given by tensoring with finite dimensional modules, such as projective functors and translation functors. We study properties of functors on O given by tensoring with arbitrary (possibly infinite dimensional) modules. Such functors give rise to a faithful action of O on itself via exact functors which preserve tilting modules, via right exact functors which preserve projective modules, and via left exact functors which preserve injective modules.Papers II and III both deal with Kostant's problem. In Paper II we establish an effective criterion equivalent to the answer to Kostant's problem for simple highest weight modules, in the case where the Lie algebra is of type A. Using this, we derive some old and new results which answer Kostant's problem in special cases. An easy sufficient condition derived from this criterion using Kazhdan-Lusztig combinatorics allows for a straightforward computational check using a computer, by which we get a complete answer for simple highest weight modules in the principal block of O for algebras of rank less than 5.In Paper III we relate the answer to Kostant's problem for certain modules to the answer to Kostant's problem for a module over a subalgebra. We also give a new description of a certain quotient of the dominant Verma module, which allows us to give a bound on the multiplicities of simple composition factors of primitive quotients of the universal enveloping algebra.
Development of Arabic Learning Media Innovation from Neuroscience Perspective for Santri: Implications in the Development of Intellectual Property Rights in Islamic Boarding Schools

This study aims to develop (1) Arabic learning media innovation with a neuroscience approach at the Babul Ulum Islamic Boarding School Pamekasan; and (2) the factors that become obstacles in learning Arabic at the Babul Ulum Islamic Boarding School in Pamekasan. (3) knowing the needs analysis of ustadz for neuroscience media, (4) designing neuroscience media prototypes, (5) analyzing the results of expert validation and revision of neuroscientific media prototypes, (6) analyzing the RND of previous learning with neuroscience media to be conveyed to students at Islamic boarding schools Babul Ulum Pamekasan. The population that was taken as the research sample by the researcher was 20 students and 1 teacher teaching Arabic. This research is research and development research. The research has been conducted on-site case studies and adapted the Rnd reference literature. The procedure for this research phase refers to the theory of Rnd Borg and Gall which was developed by Sugiyono, namely 10 steps. However, with limited time, the researcher only took 5 steps The subjects of this research are ustadz and santri in Islamic boarding schools. The results of this study are (1) research by the ustadz require the development of neuroscience media to be implemented in Arabic learning. (2) neuroscience media prototypes in the form of audio-visual learning videos that are conceptualized with interesting audio and visualizations, containing media delivery, product specifications, Arabic text, mufrodat, and muhadasah materials, operating procedures, implementation steps for using learning media, and developer profiles. (3) the results of expert validation include aspects of content/material feasibility, language feasibility aspects, presentation feasibility aspects, and graphic aspects with an overall average value of 88.21 with a very decent category, (4) neuroscience media as a means of audio-visual media emphasizes and directs santri to learn Arabic with a brain approach, stimulation from the brain as the central neuron for the growth of intelligence.
Gravity waves above a convective boundary layer: A comparison between wind‐profiler observations and numerical simulations

Wind‐profiler observations and three‐dimensional numerical modelling are used to investigate gravity waves generated over convectively active boundary layers on 12 and 13 May 2001 at Lindenberg, Germany. The results illustrate the importance of changes in the background wind and stability profile in influencing the vertical propagation of the gravity waves. The resultant changes in vertical propagation cause the dominance of relatively long‐wavelength, long‐period waves at high levels and the dominance of relatively short‐wavelength, short‐period waves near the top of the convective boundary layer. There are important differences between the two days in the wave‐propagation characteristics, due to subtle changes in the background flow conditions. Copyright © 2007 Royal Meteorological Society
Approximation theory methods for solving elliptic eigenvalue problems

Eigenvalue problems with elliptic operators L on a domain G ⊂ R2 are considered. By applying results from complex approximation theory we obtain results on the approximation properties of special classes of solutions of Lu = 0 on G . These solutions are used as trial functions in a method for solving the eigenvalue problem which is based on a‐posteriori error bounds. Singular trial functions are applied to smooth the problem at corner points of G . In special situations, this method can produce approximations of eigenvalues and eigenfunctions with extremely high accuracy by only using a low number of trial functions. Some illustrative numerical examples for the eigenvalue problem with the Laplacian are presented. We discuss two problems from plasma physics (‘relaxed plasma’, ‘MHD‐equation’).
X-ray study of superclusters

The Batuski-Burns list of candidate superclusters was searched for X-ray emission in the HEAO 1 A-2 data base. No significant flux in excess of integrated member cluster emission was detected in directions associated with estimated supercluster centroids; a 3 sigma upper limit to the mean individual excess flux is 5 x 10 to the -12th ergs/sq cm/s. Implications of this bound are discussed in terms of fainter member clusters, hot diffuse gas, and active and normal galaxies. Prospects of supercluster observations related to future X-ray missions are also outlined.
Comparison of Single-Parameter and Multiparameter Ensembles for Assimilation of Radar Observations Using the Ensemble Kalman Filter

AbstractObservational studies indicate that the densities and intercept parameters of hydrometeor distributions can vary widely among storms and even within a single storm. Therefore, assuming a fixed set of microphysical parameters within a given microphysics scheme can lead to significant errors in the forecasts of storms. To explore the impact of variations in microphysical parameters, Observing System Simulation Experiments are conducted based on both perfect- and imperfect-model assumptions. Two sets of ensembles are designed using either fixed or variable parameters within the same single-moment microphysics scheme. The synthetic radar observations of a splitting supercell thunderstorm are assimilated into the ensembles over a 30-min period using an ensemble Kalman filter data assimilation technique followed by 1-h ensemble forecasts. Results indicate that in the presence of a model error, a multiparameter ensemble with a combination of different hydrometeor density and intercept parameters leads to.
Experiments on the Fluid Mechanics of Whistling

Experiments to investigate the fluid mechanics of whistling are reported. A model, consisting of a cylindrical cavity with rounded holes at each end, is used to simulate human whistling. It is found that the frequency is very near the Helmholtz resonator frequency, and that the resonator can be excited by flow through the smooth‐edged orifices bounding the resonant cavity. Furthermore, it is found that the flow velocity of the jet which excites the resonator must lie between limits that are proportional to frequency and that increase with both diameter and thickness of the orifice. It is concluded that whistling can be included in the same class of sound sources as the Rayleigh bird call and the Pfeifentone, since the essential mechanism for exciting them depends on the instability of a jet to the formation of vortex rings and the interaction of the rings with a rigid boundary in the flow.
Unusual properties - mathematical and physical - of the a-boundary construction.

This thesis is written within the framework of the abstract boundary (or aboundary) of Scott and Szekeres, [24]. The a-boundary provides a concept of “boundary” for any n-dimensional, paracompact, connected, Hausdorff manifold, defined in such a way that the boundary is independant of the particular embedding used to display the manifold. This makes it possible to define various types of boundary points of space-time such as “singularities” and “points at infinity”. The original research that will be presented in this thesis can be roughly divided up into two categories; results relating to the existence of optimal embeddings of solutions to Einstein’s Field Equations and a-boundary singularity theorems. In addition, the implications of the “finite connected neighbourhood region property” and the bounded “acceleration” property are explored. It is also shown that not all space-times are maximally extendable.
Investigation of Dynamics of Lean Turbulent Premixed Flames by Rayleigh Imaging

Turbulent premixed flames of propane/air and methane/air were studied on a stabilized Bunsen-type burner to investigate the interactions between turbulence and the structure of the flame front in the thin reaction zones regime. The fuel-air equivalence ratio was varied from 0.7 to stoichiometric for propane flames, and from 0.6 to stoichiometric for methane flames. The nondimensional turbulence intensity u'/S L covered the range from 2.7 to 24.1. The flame front data were obtained using planar Rayleigh scattering technique, and particle image velocimetry was used to measure the instantaneous velocity field of the flames. Thermal structure of the flame front was observed to change with increasing U'/S L . The reaction zone and preheat zone thicknesses increased modestly with nondimensional turbulence intensity in both propane and methane flames. Flame front curvature statistics displayed the same Gaussian-like distribution, which centered around zero for all the flame conditions studied. Flame surface density results exhibited almost no dependence on the nondimensional turbulence intensity. It was found that the flame curvature was able to broaden the flame front and reduce the flame surface density.