Miracle-dz/UniFAR-FTUs huggingface dataset:
Preferential concentration and relative velocity statistics of inertial particles in Navier–Stokes turbulence with and without filtering

The radial distribution function (RDF, a statistical measure of preferential concentration), and the relative velocity measured along the line-of-centres of two particles are the key statistical inputs to the collision kernel for finite-inertia particles suspended in a turbulent flow Sundaram & Collins (J. Fluid Mech., vol. 335, 1997, p. 75). In this paper, we investigate the behaviour of these two-particle statistics using direct numerical simulation (DNS) of homogeneous isotropic turbulence. While it is known that the RDF for particles of any Stokes number (St) decreases with separation distance Sundaram & Collins (J. Fluid Mech., vol. 335, 1997, p. 75), Reade & Collins (Phys. Fluids, vol. 12, 2000, p. 2530), Salazar et al. (J. Fluid Mech., vol. 600, 2008, p. 245), we observe that the peak in the RDF versus St curve shifts to higher St as we increase the separation distance. Here, St is defined as the ratio of the particle's viscous relaxation time to the Kolmogorov time-scale of the flow. Furthermore, as found in a previous study Wang, Wexler, & Zhou (J. Fluid Mech., vol. 415, 2000, p. 117), the variance of the radial relative velocity (wr) is found to increase monotonically with increasing separation distance and increasing Stokes number; however, we show for the first time that the parameteric variation of the skewness of wr with St and r/η is qualitatively similar to that of the RDF, and points to a connection between the two. We then apply low-pass filters (using three different filter scales) on the DNS velocity field in wavenumber space in order to produce ‘perfect’ large-eddy simulation (LES) velocity fields without any errors associated with subgrid-scale modelling. We present visual evidence of the effect of sharp-spectral filtering on the flow structure and the particle field. We calculate the particle statistics in the filtered velocity field and find that the RDF decreases with filtering at low St and increases with filtering at high St, similar to Fede & Simonin (Phys. Fluids, vol. 18, 2006, p. 045103). We also find that the variation of the RDF with St shifts towards higher St with filtering at all separation distances. The variance of wr is found to decrease with filtering for all St and separation distances, but the skewness of wr shows a non-monotonic response to filtering that is qualitatively similar to the RDF. We consider the variation of the RDF and moments of wr with filter scale and find that they are approximately linear in the inertial range. We demonstrate that a simple model consisting of a redefinition of the St based on the time-scale of the filtered velocity field cannot recover the unfiltered statistics. Our findings provide insight on the effect of subgrid-scale eddies on the RDF and wr, and establish the requirements of a LES model for inertial particles that can correctly predict clustering and collisional behaviour.
Spatial-Filtering-Based Contributions to a Critique of Geographically Weighted Regression (GWR)

Interaction terms are constructed with georeferenced attribute variables and spatial filter eigenvectors, and then used to compute geographically varying regression coefficients. These coefficients, which are analogous to geographically weighted regression (GWR) coefficients, display preferable properties, and this specification is used to critique selected features of GWR. Comparisons are illustrated with the Georgia data appearing in the standard GWR tutorial.
Frequency and Impacts of Verbal Abuse on Healthcare Workers in a Secondary Healthcare Structure in Greece

Background: Threatening and aggressive behaviors in healthcare settings constitute a significant problem that can affect not only the physical and mental integrity of staff but also patient safety and the quality of healthcare. Literature highlights verbal abuse as the most common form of non-physical violence and is estimated from 51.8% to 63.4% worldwide. Purpose: The purpose of the study was the investigation of verbal abuse incidence toward physicians and nurses and the differences noted between them in a regional hospital. Methods: The study took place in a public regional hospital in southern Greece. A number of 185 nurses and 60 physicians completed the verbal abuse scale (VAS) for assessing verbal violence in the work environment; selected socio-demographic and occupational characteristics were also recorded. Results: Physicians have undergone verbal abuse once a week at a percentage of 38.3%, while at the same frequency; nurses record a percentage of 12.4%. Regarding the relationship between the victim of verbal abuse and the abuser, 26.7% of the physicians answered that the abuser was another senior member of the staff, while the percentage for nurses is higher and reaches 31.9%. According to VAS items, accusing and blaming (mean±SD=3.00±0.96) is noted as the most common form of verbal abuse for physicians, judging and criticizing stands out as the most frequent (3.17±1.11) and the most stressful action (3.25±1.11) form for nurses. The most frequent behavior by the physicians is to put the verbal abuse situation in a humorous context (2.78±1.14). In contrast, nurses are trying to clarify any misunderstanding that may occur (3.10±1.00). Conclusions: Verbal abuse incidents are experienced by both physicians and nurses. They are stressful for the victims and can significantly affect work relationships and job satisfaction.
A TEST OF AUTOCORRELATION IN THE PRESENCE OF HETEROSKEDASTICITY OF UNKNOWN FORM

This paper develops a test of autocorrelation in the presence of heteroskedasticity of unknown form in the nonlinear regression model. The test statistic is based on the sample autocovariance of the residuals standardized by a nonparametric kernel estimate of the unknown heteroskedasticity function. Under appropriate conditions, the test statistic is shown to have a limiting chi-square distribution. Local power and consistency results for the test are also established. Monte Carlo experiments show that the test has reasonable size performance and generally dominates some of the existing tests in terms of finite-sample power.
An Interpretation of TRMM Radar Observations of Shallow Convection with a Rain Cell Model

Observations of shallow, isolated convection from the Precipitation Radar (PR) aboard the Tropical Rainfall Measuring Mission (TRMM) observatory were compared with simulations from a rain cell model to examine effects of sub-resolution scale convection on space-borne radar observations. A large sample of shallow isolated convection was obtained from PR data over the central Pacific Intertropical Convergence Zone. Storm top heights, ranged from 1000 to 3750 m, with a mode at 1500 m. A secondary classification was made to identify 3 classes with progressively smaller spatial scales: groups of rainy fields-of-view (FOVs), rainy FOVs with one neighboring rainy FOV, and solitary rainy FOVs. Smaller spatial scales were associated with shallower storms and lower radar reflectivity (dBZ) values. The solitary class was the focus of the modeling comparison. The first objective of the modeling exercise was to explore the possibility that information on the horizontal scale and rain rate intensity of sub-resolution shallow convection could be extracted from the PR observations by finding an optimal fit between simulated and observed dBZ distributions. The height and diameter of simulated rain cells were linked by assuming an average aspect ratio of one. Simulated and observed probability distributions of dBZ were compared for two modes of rain cell variability: a fixed aspect ratio with variable cell dBZ, and a fixed cell dBZ with variable aspect ratio. Both modes resulted in excellent comparisons with observed distributions. The second modeling objective was to compare rain rates from the simulated “ground truth” and simulated “retrieved” rain rates, and to determine the effective sampling area of the modeled FOV. In general, simulated retrieved rain rates had a positive bias, as expected from the non-linear Z-R relation. However, more complex patterns of potential negative biases were evident, depending on the size and intensity of modeled rain cells.
A-Mode Ultrasound-Based Prediction of Transfemoral Amputee Prosthesis Walking Kinematics via an Artificial Neural Network

Lower-limb powered prostheses can provide users with volitional control of ambulation. To accomplish this goal, they require a sensing modality that reliably interprets user intention to move. Surface electromyography (EMG) has been previously proposed to measure muscle excitation and provide volitional control to upper- and lower-limb powered prosthesis users. Unfortunately, EMG suffers from a low signal to noise ratio and crosstalk between neighboring muscles, often limiting the performance of EMG-based controllers. Ultrasound has been shown to have better resolution and specificity than surface EMG. However, this technology has yet to be integrated into lower-limb prostheses. Here we show that A-mode ultrasound sensing can reliably predict the prosthesis walking kinematics of individuals with a transfemoral amputation. Ultrasound features from the residual limb of 9 transfemoral amputee subjects were recorded with A-mode ultrasound during walking with their passive prosthesis. The ultrasound features were mapped to joint kinematics through a regression neural network. Testing of the trained model against untrained kinematics show accurate predictions of knee position, knee velocity, ankle position, and ankle velocity, with a normalized RMSE of 9.0 ± 3.1%, 7.3 ± 1.6%, 8.3 ± 2.3%, and 10.0 ± 2.5% respectively. This ultrasound-based prediction suggests that A-mode ultrasound is a viable sensing technology for recognizing user intent. This study is the first necessary step towards implementation of volitional prosthesis controller based on A-mode ultrasound for individuals with transfemoral amputation.
A theory for the core of a leading-edge vortex

In the flow past a slender delta wing at incidence one can observe a roughly axially symmetric core of spiralling fluid, formed by the rolling-up of the shear layer that separates from a leading edge. The aim in this paper is to predict the flow field within this vortex core, given appropriate conditions at its outside edge. The basic assumptions are (i) that the flow is continuous and rotational, and (ii) that viscous diffusion is confined to a relatively slender subcore. In addition it is assumed that the flow is axially symmetric and incompressible. Together, these admit outer and inner solutions for the core from the equations of motion. For the outer solution the subcore is ignored, and the flow is taken to be inviscid (but rotational) and conical. The resulting solution consists of simple expressions for the velocity components and pressure. For the inner solution, which applies to the diffusive subcore, the flow is taken to be laminar, and certain approximations are made, some based on the boundary conditions and some analogous to those of boundary-layer theory. The solution obtained in this case is a first approximation, and has been computed. A sample calculation yields results which are in good qualitative and fair quantitative agreement with experimental measurements.
Rise and metabolic roles of Vibrio during the fermentation of crab paste

Microbial community may systematically promote the development of fermentation process of foods. Traditional fermentation is a spontaneous natural process that determines a unique nutritional characteristic of crab paste of Portunus trituberculatus, However, rare information is available regarding the development pattern and metabolic role of bacterial community during the fermentation of crab paste. Here, using a 16S rRNA gene amplicon sequencing technology, we investigated dynamics of bacterial community and its relationship with metabolites during the fermentation of crab paste. The results showed that bacterial community changed dynamically with the fermentation of crab paste which highlighted by consistently decreased α-diversity and overwhelming dominance of Vibrio at the later days of fermentation. Vibrio had a positive correlation with trimethylamine, hypoxanthine, formate, and alanine while a negative correlation with inosine and adenosine diphosphate. In contrast, most of other bacterial indicators had a reverse correlation with these metabolites. Moreover, Vibrio presented an improved function potential in the formation of the significantly increased metabolites. These findings demonstrate that the inexorable rise of Vibrio not only drives the indicator OTUs turnover in the bacterial community but also has incriminated the quality of crab paste from fresh to perished.
Electrical parameters of red sprites

Red sprites are the exotic kind of lightning above thunderstorms. Expressions for the velocity and current of sprites have been obtained. The velocity expression comes out to be Gaussian. The calculated current flowing in the sprite body behaves just like a typical lightning return stroke current. The variations of current moment and charge moment change with time have been calculated with the help of velocity and current expressions. The approximate radiation electric field generated from the current moment of sprite also has been obtained. The radiation electric field peaks at about 40 Hz with an amplitude of the order of 10 –5 V/m at 200 km from the sprite channel. The total energy dissipated in the body of red sprites is of the order of 10 9 J.
A Framework for Understanding and Cultivating the Transition from Arithmetic to Algebraic Reasoning

As organizers of this special issue and investigators in the Supporting the Transition from Arithmetic to Algebraic Reasoning (STAAR) project, we both felt we would be remiss if we did not acknowledge the singular importance of Jim Kaput’s influence on this body of work. From the earliest meetings of the project team, Jim’s deep thinking about the nature of algebra and of algebraic reasoning and instruction served as a guide. Jim contributed substantially to each of the tiers. But, more significantly, Jim appreciated the need and challenge to address each of these areas of algebra education research in a systemic manner. He agreed unflinchingly when asked to join our advisory board, and the project benefited immensely from his writings and from various discussions on the work. It is a patent understatement that his early death is a loss for the mathematics education community in general and for the community of algebra researchers in particular. Yet we are proud to say his ideas and contributions will continue in projects such as this. Therefore, it is only fitting that we dedicate this set of papers to Professor James J. Kaput. Algebraic reasoning stands as a formidable gatekeeper for students in their efforts to progress in mathematics and science, and to obtain economic opportunities (Ladson-Billings, 1998; RAND, 2003). Currently, mathematics education reMATHEMATICAL THINKING AND LEARNING, 9(3), 179–192 Copyright © 2007, Lawrence Erlbaum Associates, Inc.
Branching fraction and CP-violation charge asymmetry measurements for B-meson decays to eta K-+/-, eta pi(+/-), eta ' K, eta 'pi(+/-), omega K, and omega pi(+/-)

The authors present measurements of the branching fractions for B{sup 0} meson decays to {eta}{prime}K{sup 0} and {omega}K{sup 0}, and of the branching fractions and CP-violation charge asymmetries for B{sup +} meson decays to {eta}{pi}{sup +}, {eta}K{sup +}, {eta}{prime}{pi}{sup +}, {eta}{prime}K{sup +}, {omega}{pi}{sup +}, and {omega}K{sup +}. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 383 million B{bar B} pairs produced in e{sup +}e{sup -} annihilation. The measurements agree with previous results; they find no evidence for direct CP violation.
Exopolysaccharide-producing Lacticaseibacillus paracasei strains isolated from kefir as starter for functional dairy products

Exopolysaccharides (EPS) produced by lactic acid bacteria are molecules of great interest for the dairy food industry. Lacticaseibacillus paracasei CIDCA 8339, CIDCA 83123, and CIDCA 83124 are potentially probiotic strains isolated from kefir grains whose EPS-production on MRS broth is dependent on incubation temperature. The aim of the present work is to evaluate the effect of fermentation temperature on the characteristics of EPS produced in milk by L. paracasei strains and the consequent impact on the rheological properties of the fermented products. Additionally, the protective effect of these EPS against Salmonella infection was evaluated in vitro. Acid gels with each strain were obtained by milk fermentation at 20°C, 30°C, and 37°C evidencing for all the strains a reduction in growth and acidification rate at lower temperature. Lacticaseibacillus paracasei CIDCA 83123 showed low fermentation rate at all temperatures requiring between 3 and 8 days to obtain acids gels, whereas CIDCA 8339 and 83124 needed between 24 and 48 h even when the temperature was 20°C. Fermentation temperature led to changes in crude EPS characteristics of the three strains, observing an increase in the relative amount of the high molecular weight fraction when the fermentation temperature diminished. Additionally, EPS83124 and EPS83123 presented modifications in monosaccharide composition, with a reduction of rhamnose and an increase of amino-sugars as temperature rise. These changes in the structure of EPS83124 resulted in an increase of the apparent viscosity of milks fermented at 20°C (223 mPa.s) and 30°C (217 mPa.s) with respect to acid gels obtained at 37°C (167 mPa.s). In order to deepen the knowledge on EPS characteristics, monosaccharide composition of low and high molecular weight EPS fractions were evaluated. Finally, it was evidenced that the preincubation of intestinal epithelial cells Caco-2/TC-7 with EPS8339 and EPS83124 partially inhibit the association and invasion of Salmonella. In light of these results, it can be concluded that the selection of the EPS-producing strain along with the appropriate fermentation conditions could be an interesting strategy to improve the technological properties of these L. paracasei fermented milks with potential protective effects against intestinal pathogens.
Development of fuzzy rule-based parameters for urban object-oriented classification using very high resolution imagery

Urban areas consist of spectrally and spatially heterogeneous features. Advanced information extraction techniques are needed to handle high resolution imageries in providing detailed information for urban planning applications. This study was conducted to identify a technique that accurately maps impervious and pervious surfaces from WorldView-2 (WV-2) imagery. Supervised per-pixel classification algorithms including Maximum Likelihood and Support Vector Machine (SVM) were utilized to evaluate the capability of spectral-based classifiers to classify urban features. Object-oriented classification was performed using supervised SVM and fuzzy rule-based approach to add spatial and texture attributes to spectral information. Supervised object-oriented SVM achieved 82.80% overall accuracy which was the better accuracy compared to supervised per-pixel classifiers. Classification based on the proposed fuzzy rule-based system revealed satisfactory output compared to other classification techniques with an overall accuracy of 87.10% for pervious surfaces and an overall accuracy of 85.19% for impervious surfaces.
Hybrid simulation of shock formation for super-Alfvénic expansion of laser ablated debris through an ambient, magnetized plasma

Two-dimensional hybrid simulations of perpendicular collisionless shocks are modeled after potential laboratory conditions that are attainable in the LArge Plasma Device (LAPD) at the University of California, Los Angeles Basic Plasma Science Facility. The kJ class 1053 nm Nd:Glass Raptor laser will be used to ablate carbon targets in the LAPD with on-target energies of 100-500 J. The ablated debris ions will expand into ambient, partially ionized hydrogen or helium. A parameter study is performed via hybrid simulation to determine possible conditions that could lead to shock formation in future LAPD experiments. Simulation results are presented along with a comparison to an analytical coupling parameter.
Modeling of Two Northwest Atlantic Storms with Third-Generation Wave Models

Abstract In this study, three state-of-the-art operational forecast wave models are implemented on nested grids in order to achieve fine-resolution wave simulations (0.1°) in the Gulf of Maine and related northwest Atlantic waters. These models are the Simulating Waves Nearshore (SWAN) model, the Wave Action Model (WAM), and WAVEWATCH-III (hereafter WW3). Model performance is evaluated through comparisons with field measurements. Four composite model systems are compared: WAM and WW3 implemented on three nested domains, SWAN nested within WAM, and SWAN nested within WW3. Storm case studies include two intense midlatitude winter storms from January 2000 and January 2002. Although the models are comparable in terms of their overall performance and skill, it is found that WW3 provides a better statistical fit to the observed wave data compared with the other models, and that SWAN gives slightly better results if nested within WW3, rather than within WAM.
Transverse waves in numerical simulations of cellular detonations

In this paper the structure of strong transverse waves in two-dimensional numerical simulations of cellular detonations is investigated. Resolution studies are performed and it is shown that much higher resolutions than those generally used are required to ensure that the flow and burning structures are well resolved. Resolutions of less than about 20 numerical points in the characteristic reaction length of the underlying steady detonation give very poor predictions of the shock configurations and burning, with the solution quickly worsening as the resolution drops. It is very difficult and dangerous to attempt to identify the physical structure, evolution and effect on the burning of the transverse waves using such under-resolved calculations. The process of transverse wave and triple point collision and reflection is then examined in a very high-resolution simulation. During the reflection, the slip line and interior triple point associated with the double Mach configuration of strong transverse waves become detached from the front and recede from it, producing a pocket of unburnt gas. The interaction of a forward facing jet of exploding gas with the emerging Mach stem produces a new double Mach configuration. The formation of this new Mach configuration is very similar to that of double Mach reflection of an inert shock wave reflecting from a wedge.
Nb3Sn nucleation and growth in multifilament superconducting strands monitored by high resolution synchrotron diffraction during in situ reaction

The Nb3Sn volume, crystallite size, and Sn content evolution during the reaction of a recent high critical current density Nb3Sn/Cu composite wire has been monitored by high energy, high resolution synchrotron x-ray diffraction. Thanks to the high flux of high energy x-rays at the ID15A beamline of the European Synchrotron Radiation Facility. It was possible to monitor the Nb3Sn crystallite growth in situ from the early stages of Nb3Sn nucleation at 540 °C up to nearly complete transformation of the Nb precursor into Nb3Sn. Simultaneously, the uptake of Sn in the A15 phase could be monitored by Nb3Sn lattice parameter measurements.