Miracle-dz/UniFAR-FTUs huggingface dataset:
Evolution and dissipation of imbedded rotational discontinuities and Alfvén waves in nonuniform plasma and the resultant proton heating

We show that nonuniform Alfven speed gradients across field lines generally arise from the evolution of Alfven waves. The evolution of a group of nonlinear Alfven waves with the same sign of parallel wavenumber generate small-amplitude pressure-balanced structures (PBSs) which cause the speed variations. This always causes refraction. In most cases, the Alfven waves also couple to magnetosonic waves and acquire a weak compressional component and can undergo resonant absorption or transfer, wherein wave energy can propagate across field lines. At large amplitudes the waves also generate imbedded rotational discontinuities (RDs). Some of these RDs can be dissipated owing to resonant transfer. This process could partly contribute to the observed decrease of solar wind RDs with increasing distance from the Sun. Resonant transfer also triggers a cascade due to steepening, which leads to sustained proton heating. The cascade produces oblique and large wavenumber waves which travel in different directions and have associated compressions. Protons interact with these by pitch angle scattering. They gain energy from second-order Fermi acceleration and from Landau and transit time damping. Oblique waves are inferred to be present in the dissipation range of Alfvenic fluctuations at 1 AU. We argue that the process of proton heating should proceed similarly to simulation results. We also propose a role for the wave imbedded RD in coronal heating through its formation in the chromosphere and its likely dissolution in the corona where wave amplitudes are very small.
Relationships between convective asymmetry, imbalance and intensity in numerically simulated tropical cyclones

This article examines the relationships between convective asymmetry (CA), imbalance and intensity in tropical cyclones (TCs) that emerge from random winds on the periodic f-plane in a cloud-system-resolving numerical model. The model is configured with warm-rain microphysics and includes a basic parameterisation of long-wave radiation. Within the simulation set, the sea-surface temperature ranges from 26 to 32°C, and the Coriolis parameter f ranges from 10−5 to 10−4 s−1. The number of TCs that develop in a simulation increases rapidly with f and ranges from 1 to 18. Taken together, the simulations provide a diverse spectrum of vortices that can be used for a meaningful statistical study. Consistent with earlier studies, mature TCs with minimal asymmetry are found to have maximum wind speeds greater than the classic theoretical value derived by Emanuel under the assumptions of gradient-wind and hydrostatic balance. In a statistical sense, it is found that the degree of superintensity with respect to balance theory reliably decays with an increasing level of inner-core CA. It is verified that a more recent version of axisymmetric steady-state theory, revised to incorporate imbalance, provides a good approximation for the maximum (azimuthally averaged) azimuthal wind speed V max when CA is relatively weak. More notably, this theory for axisymmetric vortices maintains less than 10% error as CA becomes comparable in magnitude to the symmetric component of inner-core convection. Above a large but finite threshold of CA, axisymmetric steady-state theory generally over-predicts V max. The underachievement of TCs in this parameter regime is shown to coincide with substantial violation of the theoretical assumption of slantwise convective neutrality in the main updraft of the basic state. Of further interest, a reliable curve-fit is obtained for the anticorrelation between a simple measure of CA and V max normalised to an estimate of its balanced potential intensity that is based solely on environmental conditions and air–sea interaction parameters. Sensitivity of results to the surface-flux parameterisation of the numerical model is briefly discussed.
Third order point process intensity estimation for reaction time experiment data

The authors consider a simple parametric model for data from a point process version of a reaction time experiment to test the nature of thinning mechanisms in the presence of nonlinear inhibition in the eye‐brain‐hand system. In particular, they study the effects of two such mechanisms on the third order intensity estimate. An alternative nonparametric estimate is also considered in this context. These various approaches are applied on twelve runs of real data, but the analysis turns out to be inconclusive: neither mechanism can be ruled out, nor the possibility that their effects could be combined.
The heliospheric neutral hydrogen density profile in the presence of a solar wind shock

The effect of a postulated nearby solar wind shock on the radial density profile of the cold inflowing neutral hydrogen atoms is studied. It is found that a nearby solar wind shock strongly affects the neutral hydrogen breeze. Model calculation reveals that the strongly perturbed hydrogen atom distribution beyond a solar wind shock can be remotely detected by observation of the radial dependence of the backscattered UV glow from the deep space probes Pioneer 10/11 and Voyager 1/2. 33 references.
STM/STS STUDY ON LOCAL ELECTRONIC STATES OF UNDERDOPED Bi2Sr2CaCu2O8+δ

Spatial variation of low temperature tunneling spectrum on atomic scale was examined on the slightly underdoped Bi2212 sample (Tc~74K, p~0.12) by using a STM/STS technique. We observed a V-shaped gap with sharp coherence peaks, which is expected for d-wave superconductors, over the distance of ~18 nm and no other kind of gap. The spatial variation of gap size Δ0 is small, ranging from 41 to 53 meV. These results indicate that the superconductivity takes place rather homogeneously in the slightly underdoped sample.
Overview of the advanced photon source (invited)

The Advanced Photon Source planned for construction at Argonne National Laboratory is based on a low‐emittance storage‐ring operated at 7 GeV and capable of providing tunable undulator radiation from 4 to 40 keV (using the first and the third harmonics). A technical description of the accelerator facility and the storage ring is presented in this overview, along with a brief summary of the characteristics of radiation that will be available from the insertion devices. Various plans for user access to this national user facility are also given.
The Top of the Lattice of Normal Subgroups of the Grigorchuk Group

Abstract A complete description of the lattice of all normal subgroups not contained in the stabilizer of the fourth level of the tree and, consequently, of index ≤ 2 12 in the Grigorchuk group G is given. This leads to the following sharp version of the congruence property : a normal subgroup not contained in the stabilizer at level n + 1 contains the stabilizer at level n + 3 (in fact such a normal subgroup contains the subgroup N n + 1 ), but, in general, it does not contain the stabilizer at level n + 2. The determination of all normal subgroups at each level n ≥ 4 is then reduced to the analysis of certain G -modules which depend only on n and the previous description, as for the analogous problem for the automorphism group of the regular rooted tree.
Broad band X-ray Telescope observations of the hot interstellar media in NGC 1399 and NGC 4472

We present our analysis and interpretation of spatially resolved X-ray spectroscopy of the elliptical galaxies NGC 1399 and NGC 4472 obtained with the Broad Band X-Ray Telescope. The X-ray emission from both galaxies is dominated by thermal emission from a hot interstellar medium. The temperature of the plasma in NGC 1399 is 1.0-1.2 keV with a mild positive temperature gradient; for NGC 4472 the average temperature is 0.7-1.0 keV. The temperature of NGC 1399, when combined with other X-ray and optical data, implies that, if the gas is gravitationally confined, about 70 percent of the mass inside a radius of about 8.6 arcmin (38 kpc) is nonluminous. The derived metallicities and metallicity gradients are consistent with optically determined stellar metallicities, and allow surprisingly small upper limits to be placed on Type Ia supernovae rates in both galaxies. The implications of this for the gasdynamical evolution of the two galaxies are discussed. Limits on the oxygen-to-iron ratio and the line-of-sight column density are derived. There is a possible detection of cold gas in the line of sight to NGC 1399 that exceeds the Galactic value. Constraints on the contribution from a harder spectral component are placed, and likely candidates for the origin of this secondary component are evaluated.
Development of Superconducting RF Technology

The development of superconducting RF cavity technology started in the 1960s, aiming for continuous wave operation of high gradient linacs with excellent electric power efficiency. After continuous efforts for more than four decades, the initial achievable field gradient of only 2 MV/m was gradually improved and approached the theoretical upper limit of 50 MV/m on Nb cavities. At each stage of this development, many applications have been extended in various fields. This article will review those advances and applications of the superconducting RF cavities.
A Hybrid Combination Scheme for Cooperative Spectrum Sensing in Cognitive Radio Networks

We propose a novel hybrid combination scheme in cooperative spectrum sensing (CSS), which utilizes the diversity of reporting channels to achieve better throughput performance. Secondary users (SUs) with good reporting channel quality transmit quantized local observation statistics to fusion center (FC), while others report their local decisions. FC makes the final decision by carrying out hybrid combination. We derive the closed-form expressions of throughput and detection performance as a function of the number of SUs which report local observation statistics. The simulation and numerical results show that the hybrid combination scheme can achieve better throughput performance than hard combination scheme and soft combination scheme.
A Motion Edge Extraction Method under the Condition of Camera Swing

Motion edge extraction is the object of most motion segmentation methods. We have proposed a motion edge extraction method in our previous work. However, if the camera swings, a number of background edges are classified into foreground edges. In order to solve this problem, we propose a background pixel relating method to modify the motion model and to remove those misclassified edges. At the end of this paper, we use the CAVIAR project test sequence to test our method. The result is satisfactory.
A high-accuracy temporal–spatial pseudospectral method for time-periodic unsteady fluid flow and heat transfer problems

A temporal–spatial pseudospectral (TSP) method is proposed for the high-accuracy solutions of time-periodic unsteady fluid flow and heat transfer problems. In this method, both the spatial and temporal derivative terms in the governing equations are computed by pseudospectral method. The spatial derivatives are computed through Chebyshev and Lagrange polynomials while the time derivatives are computed by Fourier series. The TSP method is capable of directly finding out the periodic state solutions without the necessity to resolve the initial transient state solutions, hence holds high computational efficiency and high numerical accuracy properties for the time-periodic problems. This method is validated by three 2D benchmark problems: the time-periodic incompressible flow with exact solutions; the natural convection in enclosure with time-periodic temperature on one sidewall, and on both sidewalls. The TSP results fit well the exact solutions or the benchmark solutions and the TSP accuracy is much higher than the time marching spatial pseudospectral accuracy. Some time-dependent fluid flow and heat transfer characteristic parameters are analysed. The proposed TSP method could be further extended to more complex time-periodic unsteady fluid flow and heat transfer problems where high-accuracy results are required.
Psychological Flourishing of Postgraduate Students in Klang Valley, Malaysia

Across the world including Malaysia, the rate of mental health issues has become increasingly concerning especially among young adults. However, much is still unknown about the psychological flourishing of postgraduate students despite the steady increase in student enrolments into postgraduate programmes as Malaysia anticipates the emergence of a skilled talent pool to advance the nation’s economic growth. Thus, this quantitative study explored the psychological flourishing of Malaysian postgraduate students in Klang Valley by examining whether there are significant differences based on their sociodemographic characteristics. A total of 240 postgraduate students participated in this study and completed a set of questionnaires online that measured their psychological flourishing and demographic characteristics. The results showed that there were significant differences in the psychological flourishing of postgraduate students based on their age group and field of study. However, this study did not find any significant differences in postgraduate students’ level of psychological flourishing based on their gender, ethnicity, level of postgraduate programme, the structure of programme, mode of programme, and year of programme. The findings of this study had several practical implications for postgraduate students, faculty members, and on-campus counsellors. Finally, the limitations of this study and recommendations for future studies are also addressed.
Multipole (E1, M1, E2, M2, E3, M3) transition wavelengths and rates between 3l−15l′ excited and ground states in nickel-like ions

A relativistic many-body method is used to calculate energy and transition rates for multipole transitions in many-electron ions. This method is based on relativistic many-body perturbation theory (RMBPT), agrees with MCDF calculations in lowest order, includes all second-order correlation corrections and includes corrections from negative energy states. Reduced matrix elements, oscillator strengths and transition rates are calculated for electric-multipole (dipole (E1), quadrupole (E2) and octupole (E3)) and magnetic-multipole (dipole (M1), quadrupole (M2) and octupole (M3)) transitions between 3l−15l′ excited and ground states in Ni-like ions with nuclear charges ranging from Z = 30 to 100. The calculations start from a 1s22s22p63s23p63d10 Dirac–Fock potential. First-order perturbation theory is used to obtain intermediate-coupling coefficients, and second-order RMBPT is used to determine the matrix elements. A detailed discussion of the various contributions to the dipole matrix elements and energy levels is given for nickel-like tungsten (Z = 74). The contributions from negative-energy states are included in the second-order E1, M1, E2 M2, E3 and M3 matrix elements. The resulting transition energies and transition rates are compared with experimental values and with results from other recent calculations. These atomic data are important in modelling of M-shell radiation spectra of heavy ions generated in electron beam ion trap experiments and in M-shell diagnostics of plasmas.
Dynamic High Pressure: a novel approach toward near ambient pressure photoemission spectroscopy and spectromicroscopy

A Dynamic High Pressure (DHP) system has been developed, tested and implemented in the scanning photoelectron microscope (SPEM) operated at ESCAmicroscopy beamline at Elettra synchrotron. The system consists of a compact gas injection set up that allows experiments with local pressure near the sample several orders of magnitude higher that the allowable pressure for X-ray photoelectron spectroscopy setups. The DHP setup controls the amount of gas injected toward the sample by fine tuning the time and spatial profiles using a pulsed valve and a nozzle, respectively. The DHP functionality and effectiveness has been demonstrated by in operando oxidation experiments of Ru and Si. The obtained results confirmed that using the DHP the gas exposure onto the sample is equivalent to a static pressure between 10−3 and 10−2 mbar, about 3 orders of magnitude higher than the maximum gas pressure for the XPS machines under operation.
Parametric curve approximation using ICP reparametrization

Parametric curve approximation technique is frequently used in many fields of computer science. The most difficult problem in parametric curve approximation is parameterization. In this paper an Iterative Closest Point reparametrization strategy is presented to improve the precision of approximation. Moreover, this paper proves the local convergence of the algorithm, which makes it more theoretically reasonable and robust. Some results comparing with traditional approaches are given to illustrate the validity of our approach.
Simple method for estimation of global motion parameters using sparse translational motion vector fields

A simple method for the estimation of global motion parameters from sparse translational vector fields is presented. Differential operations on pairs of adjacent motion vectors are used to derive local estimates of rotation and change of scale. A majority vote is then applied to identify global trends corresponding to the required estimates. Key features of the proposed technique are its low complexity and its compatibility with standardised motion estimation tools.
Vortex Identification Methodology for Feed Insertion Guidance in Fluid Mixing Processes

Abstract A vortex tracking methodology is developed to determine the precessional frequency and the characteristics of macroinstability (MI) vortices. The methodology is compared with other techniques, frequency analysis and correlation coeffcient, which are most commonly used to assess periodicities in a flow. Two sets of experiments were carried out, 2D PIV and two-point LDA, in two different scaled vessels of diameter 80 mm and 294 mm. The MI characteristics were studied for two different Re (i.e., 32 000 and 3200) by correlating the vortex intensity (vorticity and pressure suction) with its radius at different axial positions. This study provides relevant data for the optimisation of mixing time as it indicates ‘preferred’ positions, on the path of the MI vortex, where the insertion of a second phase should take place in order to fully exploit the suction potential of the MI vortex.
Design of a stacked loops antenna array to produce dual circularly polarized and multibeam radiations

This paper presents the design of an antenna array utilizing stacked multiloop structures to produce the electromagnetic radiations with dual circular polarizations and multiple directional beams. In particular, with a proper design of isolations, each combination of these polarizations and beams can be operated in a relatively independent fashion to increase the system capacity by using a single antenna set. The antenna structure was validated by numerical simulations and experimental measurements, which are presented to exhibit the characteristics of radiation.
Nested coordinate descent algorithms for empirical likelihood

Empirical likelihood (EL) as a nonparametric approach has been demonstrated to have many desirable merits. While it has intensive development in methodological research, its practical application is less explored due to the requirements of intensive optimizations. Effective and stable algorithms therefore are highly desired for practical implementation of EL. This paper bears the effort to narrow the gap between methodological research and practical application of EL. We try to tackle the computation problems, which are considered difficult by practitioners, by introducing a nested coordinate descent algorithm and one modified version to EL. Coordinate descent as a class of convenient and robust algorithms has been shown in the existing literature to be effective in optimizations. We show that the nested coordinate descent algorithms can be conveniently and stably applied in general EL problems. The combination of nested coordinate descent with the MM algorithm further simplifies the computation. The nested coordinate descent algorithms are a natural and perfect match with inferences based on profile estimation and variable selection in high-dimensional data. Extensive examples are conducted to demonstrate the performance of the nested coordinate descent algorithms in the context of EL.
ON THE SHAPE OF GRANULAR FRONTS DOWN ROUGH INCLINED PLANES

The shape of fronts obtained when releasing a cohesionless granular material at the top of a rough inclined plane is experimentally investigated. The measurements are compared with theoretical predictions given by a model based on a depth averaged momentum equation. Good agreement is found when the empirical friction law proposed in a previous study [O. Pouliquen, Phys. Fluids 11, 542 (1999)] is introduced in the model.
The valuation of American call options on the minimum of two dividend-paying assets

This paper examines the valuation of call options on the minimum of two dividend-paying assets. We show that the optimal exercise boundary consists of three components, two continuous curves and one component along the diagonal with empty interior. The option price is shown to satisfy the early exercise premium representation in which the gains from exercise involve the local time of the minimum of the two underlying asset prices. A system of recursive integral equations for the exercise boundary components is derived. Using a class of simple stopping times we also construct lower and upper bounds for the American call min-option price: these are easy to compute and can be employed to design efficient approximations of the contract value.
Global Large-Data Solutions in a Chemotaxis-(Navier–)Stokes System Modeling Cellular Swimming in Fluid Drops

In the modeling of collective effects arising in bacterial suspensions in fluid drops, coupled chemotaxis-(Navier–)Stokes systems generalizing the prototype have been proposed to describe the spontaneous emergence of patterns in populations of oxygen-driven swimming bacteria. Here, κ ∈ ℝ and the gravitational potential φ are given and Ω ⊂ ℝ N is a bounded convex domain with smooth boundary. Under the boundary conditions and u = 0 on ∂Ω, it is shown in this paper that suitable regularity assumptions on the initial data entail the following: • If N = 2, then the full chemotaxis-Navier–Stokes system (with any κ ∈ ℝ) admits\p0 a unique global classical solution. • If N = 3, then the simplified chemotaxis-Stokes system (with κ = 0) possesses at\p0 least one global weak solution. In particular, no smallness condition on either φ or on the initial data needs to be fulfilled here, as required in a related recent work by Duan et al. [5].
On the Occurrence of Stream Overflow in Cataclysmic Variables with Accretion Disks

I consider the occurrence of the flow of accretion stream material past the edge of an accretion disk in cataclysmic variables. If the stream from the secondary star is geometrically thicker than the rim of the accretion disk, some fraction of the stream material can flow over and under the disk. The results of vertical-structure calculations for α-model disks indicate that the amount of overflow is a sensitive function of the general thermal state of the disk (e.g., cold and optically thick or warm and optically thin) but not of the value of the disk viscosity parameter α and probably not of the disk radius (i.e., the orbital period). Using the mass-transfer rates and the orbital parameters of well-studied systems, I estimate the amount of overflow for a number of individual objects and show that observationally significant stream overflow should mainly occur in quiescent dwarf novae with cold outer disks.