Situations Of Interest Research Articles

Self-consistent one dimension in space and three dimension in velocity kinetic trajectory simulation model of magnetized plasma-wall transition

We have developed a self-consistent 1d3v (one dimension in space and three dimension in velocity) Kinetic Trajectory Simulation (KTS) model, which can be used for modeling various situations of interest and yields results of high accuracy. Exact ion trajectories are followed, to calculate along them the ion distribution function, assuming an arbitrary injection ion distribution. The electrons, on the other hand, are assumed to have a cut-off Maxwellian velocity distribution at injection and their density distribution is obtained analytically. Starting from an initial guess, the potential profile is iterated towards the final time-independent self-consistent state. We have used it to study plasma sheath region formed in presence of an oblique magnetic field. Our results agree well with previous works from other models, and hence, we expect our 1d3v KTS model to provide a basis for the studying of all types of magnetized plasmas, yielding more accurate results.

Use of sugars and sweeteners in children's diets. Recommendations of the Nutrition Committee of the Spanish Association of Paediatrics

Abstract The term “sweetener” refers to a food additive that imparts a sweet flavour and usually provides no or very low energy. It is used to sweeten foods, medicines and food supplements with no nutritional purposes. For years, no-calorie sweeteners have been used as substitutes for all or part of the sugar content in foods and beverages. In recent decades its consumption has risen to prevent tooth decay, or as an aid in weight control, obesity and diabetes and, in general, to achieve an optimal energy balance. However, consumption of sugary or sweetened food and soft drinks is high, making this situation of special interest in calorie intake and in the poor behavioural pattern of eating habits in children. In addition, questions remain among consumers about the risks to health associated with their use, whether they are artificial or natural. The “artificial sweeteners” are the group of greatest interest in research in order to demonstrate their safety and to provide firm data on their possible therapeutic effects. The aim of the present document is to increase information for paediatricians on the characteristics of different sweeteners, and to advise on the choice of sweeteners, based on their properties.

Inverse modeling of pan heating in domestic cookers

The heating uniformity of the cooking vessels in domestic stoves depends on the type of heat source (induction, electric resistance, gas burner, etc.) and of the way in which the power is transferred to the pan. The evaluation of the stove functionalities is currently carried out by the manufacturers with costly experimental tests with real food, which are an important phase of the design process for the improvement of their performance in the food elaboration. In order to help to design the cookers and avoid the expensive tests, it is interesting to know how the heating power is distributed in each situation, so that the cookers can be adapted to obtain a more uniform heating. The contribution of this work is an inverse thermal model for the three aforementioned technologies of domestic cookers, which allows the calculation of the power distribution generated in the bottom of the pan from the measurement of the surface temperature. The results show that the proposed inverse model is of interest in many practical situations and can be used under diverse conditions.

Self-tuning at large (distances): 4D description of runaway dilaton capture

We complete here a three-part study (see also arXiv:1506.08095 and arXiv:1508.00856 ) of how codimension-two objects back-react gravitationally with their environment, with particular interest in situations where the transverse ‘bulk’ is stabilized by the interplay between gravity and flux-quantization in a dilaton-Maxwell-Einstein system such as commonly appears in higher-dimensional supergravity and is used in the Supersymmetric Large Extra Dimensions (SLED) program. Such systems enjoy a classical flat direction that can be lifted by interactions with the branes, giving a mass to the would-be modulus that is smaller than the KK scale. We construct the effective low-energy 4D description appropriate below the KK scale once the transverse extra dimensions are integrated out, and show that it reproduces the predictions of the full UV theory for how the vacuum energy and modulus mass depend on the properties of the branes and stabilizing fluxes. In particular we show how this 4D theory learns the news of flux quantization through the existence of a space-filling four-form potential that descends from the higher-dimensional Maxwell field. We find a scalar potential consistent with general constraints, like the runaway dictated by Weinberg’s theorem. We show how scale-breaking brane interactions can give this potential minima for which the extra-dimensional size, l, is exponentially large relative to underlying physics scales, r B , with l 2 = r 2 e − φ where −φ ≫ 1 can be arranged with a small hierarchy between fundamental parameters. We identify circumstances where the potential at the minimum can (but need not) be parametrically suppressed relative to the tensions of the branes, provide a preliminary discussion of the robustness of these results to quantum corrections, and discuss the relation between what we find and earlier papers in the SLED program.

Path instability on a sphere towed at constant speed

The dynamics of towed objects in a fluid environment is of interest for many practical situations. In this paper we report results for wake instabilities of spheres towed in a water tank. Six particles of different diameter and/or density ratio have been investigated, towed at 5 different constant velocities. The explored density ratios lay within Γ∈[1.06;2.56], with particle Reynolds numbers Rep∈[100;1200], corresponding to Galileo numbers in the range Ga∈[1300;8000]. We introduce a surrogate Galileo number Ga⁎ that, by taking into account the towing force applied to the particle, allows a comparison with the case of free falling/ascending spheres. Using innovative 3D tracking techniques, the three-dimensional trajectory of each particle is reconstructed. The wake instability for the studied particles is found to be associated to a 3D helicoidal motion with an elliptical cross section in the plane perpendicular to the towing direction. The 3D oscillatory motion was found independent of the particle density ratio, with a threshold of the order of Repc~355 (or Ga⁎c~245). This threshold is slightly larger than the one found for the free falling particles’ transition to 3D chaotic motions (Repc~310 or Gac~225).

New Solution of Diffusion–Advection Equation for Cosmic-Ray Transport Using Ultradistributions

In this paper we exactly solve the diffusion-advection equation for cosmic-ray transport. With this purpose we use the Theory of Ultradistributions of J. Sebastiao e Silva, to give a general solution for this equation. From this solution, we obtain several approximations as limiting cases of various situations of physical and astrophysical interest. One of them involves Solar cosmic-rays' diffusion.

Neutrino quantum kinetic equations

Neutrinos propagate in astrophysical and cosmological environments modifying their flavor in intriguing ways. The study of neutrino propagation in media is based on the mean-field, extended mean-field and Boltzmann equations. We summarize salient features of these evolution equations and the methods employed so far to derive them. We emphasize applications to situations of observational interest.

Electromagnetic and gravitational signatures of accretion into black holes

In this paper, the gravitational and electromagnetic signals due to accretion of charged fluids into a Schwarzschild black hole is revisited. We set up the perturbed Einstein equations and Maxwell equations coupled to the fluid equations on a stationary black hole as a system of differential equations that can be integrated as an initial value problem. We numerically investigate cases in which we varied the properties of the fluid. Our scenario may provide an electromagnetic counterpart to gravitational waves in many situations of interest, enabling easier extraction and verification of gravitational waveforms from gravitational wave detection. We find that the features of the resulting electromagnetic signals depend on the properties and dynamics of the flow.

A new DSS based on situation awareness for smart commerce environments

Real time adaptation of marketing strategies and actions in smart commerce environments, such as shops and malls, is an open challenge with a tremendous impact for the survival of traditional retailers. A main issue of traditional retailers, in comparison with e-commerce shops, is that they usually rely on analysis of point-of-sales data after purchase and/or focus groups and self-reports where customers are asked about what they like or want. This techniques, even if solid grounded to marketing and consumer research, do not allow analysis of data and decision making in real time, i.e., when consumers are inside a shop. In this paper we present our results on the definition and validation of a decision support system for real time decision making on discount and promotion actions. The system makes decision on the basis of recognition and assessment of situations of interest for the consumers, modelled with heuristics related to behavioural economics results. We validated our solution in a virtual shop simulated with V-REP, demonstrating its capabilities to adapt with regards to the changes in the environments, in terms of sensors, people, products, and different situations.

The uncertainty of conditional returns, volatilities and correlations in DCC models

Point forecasts can be obtained at each moment of time when forecasting conditional correlations that evolve according to a Dynamic Conditional Correlation (DCC) model. However, measuring the uncertainty associated with these forecasts is of interest in many situations. The finite sample properties of a bootstrap procedure for approximating the forecast densities of future returns, volatilities and correlations, are analyzed using simulated data and illustrated by obtaining conditional forecast intervals and regions in the context of a three-dimensional system of daily exchange rate returns.

Uso de azúcares y edulcorantes en la alimentación del niño. Recomendaciones del Comité de Nutrición de la Asociación Española de Pediatría

The term «sweetener» refers to a food additive that imparts a sweet flavour and usually provides no or very low energy. It is used to sweeten foods, medicines and food supplements with no nutritional purposes. For years, no-calorie sweeteners have been used as substitutes for all or part of the sugar content in foods and beverages. In recent decades its consumption has risen to prevent tooth decay, or as an aid in weight control, obesity and diabetes and, in general, to achieve an optimal energy balance. However, consumption of sugary or sweetened food and soft drinks is high, making this situation of special interest in calorie intake and in the poor behavioural pattern of eating habits in children. In addition, questions remain among consumers about the risks to health associated with their use, whether they are artificial or natural. The «artificial sweeteners» are the group of greatest interest in research in order to demonstrate their safety and to provide firm data on their possible therapeutic effects. The aim of the present document is to increase information for paediatricians on the characteristics of different sweeteners, and to advise on the choice of sweeteners, based on their properties.

Modelling and Analysis of Electrical Potentials Recorded in Microelectrode Arrays (MEAs).

Microelectrode arrays (MEAs), substrate-integrated planar arrays of up to thousands of closely spaced metal electrode contacts, have long been used to record neuronal activity in in vitro brain slices with high spatial and temporal resolution. However, the analysis of the MEA potentials has generally been mainly qualitative. Here we use a biophysical forward-modelling formalism based on the finite element method (FEM) to establish quantitatively accurate links between neural activity in the slice and potentials recorded in the MEA set-up. Then we develop a simpler approach based on the method of images (MoI) from electrostatics, which allows for computation of MEA potentials by simple formulas similar to what is used for homogeneous volume conductors. As we find MoI to give accurate results in most situations of practical interest, including anisotropic slices covered with highly conductive saline and MEA-electrode contacts of sizable physical extensions, a Python software package (ViMEAPy) has been developed to facilitate forward-modelling of MEA potentials generated by biophysically detailed multicompartmental neurons. We apply our scheme to investigate the influence of the MEA set-up on single-neuron spikes as well as on potentials generated by a cortical network comprising more than 3000 model neurons. The generated MEA potentials are substantially affected by both the saline bath covering the brain slice and a (putative) inadvertent saline layer at the interface between the MEA chip and the brain slice. We further explore methods for estimation of current-source density (CSD) from MEA potentials, and find the results to be much less sensitive to the experimental set-up.

Precedence tree guided search for the efficient identification of multiple situations of interest – AND/OR graph matching

Intelligence analysis is a domain characterized by a torrent of streaming data within which a very small portion contains useful knowledge or actionable intelligence. Intelligence analysts have to sift through the compiled data and weave through a complex web of convoluted connections in an attempt to illuminate information requirements (IR) and maintain situational awareness. Automated methodologies have eased the manual burden of this process to some extent. Data are naturally modeled in a graphical form representing the known people, places, events and the relationships between them. Graph matching algorithms in which an information requirement is formulated as a template graph or situation of interest to be found in the observed data graph have been successfully employed in intelligence analysis processes. Absent from these past contributions is the recognition that partial information requirements, such as indicators and warnings, are not mutually exclusive to a specific IR, and an understanding of the characteristics of the underlying data can lead to significant performance benefits. The knowledge of overlapping template sections forms the motivation for precedence tree guided search and AND/OR templates. Through the recognition of the overlapping sections, a single AND/OR template can be created to answer many information requirements. This paper presents a novel algorithm for the intelligent traversal of an AND/OR template, providing increased algorithmic efficiency over the execution of multiple sequential graph matching instances. This paper focuses on development of an algorithm for intelligent AND/OR template traversal with computational results illustrating the effectiveness of the developed methods. The results indicate a significant improvement in runtime (with a speedup over 5 in some cases) while maintaining a good solution quality (within 2% of multiple AND path graph matching executions) in AND/OR and precedence tree guided graph matching.

ANALYSIS OF UNDERLYING RISK FACTORS BANKRUPTCY OF ENTERPRISES

In 2014, it became clear that Russia's new economic crisis began. Expected to occur and the deepening financial and economic problems for companies and organizations, increasing the risk of insolvency, bankruptcies, lowering income taxes and contributions to the budget system of the state and non-budgetary funds, reducing the ability to solve pressing social issues. Decided to implement the state anti-crisis plan. To stabilize the economy by the Government of the Russian Federation will be further allocated at least 1.4 trillion rubles. According to First Deputy Prime Minister II Shuvalov in the subjects of the federation until February 16 to be formed anti-crisis commission and develop a plan to respond to the crisis. In connection with the situation of particular interest is the study of the risk of bankruptcy of the real sector of the economy. We consider this problem in detail on the basis of the Russian statistical observation.

Does the Russell Viper Venom time test provide a rapid estimation of the intensity of oral anticoagulation? A cohort study

BackgroundDilute Russell Viper Venom Time (DRVV-T) might be useful in urgent settings for screening patients on Non-VKA Oral Anticoagulants (NOACs). AimTo compare the accuracy of DRVV-T with gold standard assays for the assessment of pharmacodynamics of dabigatran, rivaroxaban and vitamin K antagonist (VKA) in plasma samples from patients. MethodsSixty rivaroxaban, 48 dabigatran and 50 VKA samples from patients were included. DRVV-T was performed in all groups using STA®-Staclot®DRVV-Screen and -Confirm. For NOACs, PT and aPTT were performed using different reagents while plasma drug concentrations were measured by liquid mass-spectrometry (LC-MS/MS). For VKA, INR was performed using RecombiPlasTin 2G®. ResultsFor NOACs, correlations between calibrated STA®-Staclot®DRVV-Confirm and LC-MS/MS (rs=0.88 and 0.97 for rivaroxaban and dabigatran, respectively) were higher than the ones obtained with STA®-Staclot®DRVV-Screen (rs=0.87 and 0.91), PT (rs=0.83 to 0.86) or aPTT (rs=0.84 to 0.89). Bland Altman analyses showed that calibrated DRVV-T methods tend to overestimate plasma concentrations of NOACs. ROC curves revealed that cut-off to exclude supra-therapeutic levels at Ctrough (i.e. 200ng/mL) are different for dabigatran and rivaroxaban. Neither STA®-Staclot®DRVV-Screen nor –Confirm correlated sufficiently with the intensity of VKA therapy (rs=0.35 and 0.52). ConclusionsSTA®-Staclot®DRVV-Confirm provides a rapid estimation of the intensity of anticoagulation with rivaroxaban or dabigatran without specific calibrators. At Ctrough, thresholds for rivaroxaban and dabigatran can be used to identify supra-therapeutic plasma level. However, this test cannot differentiate the nature of the NOACs. The development of a point-of-care device optimising this method would be of particular interest in emergency situations.

Characterization of temporal pulse broadening for horizontal propagation in strong anisotropic atmospheric turbulence.

The on-axis two-frequency mutual coherence function (MCF) for beam waves propagating along a horizontal path in strong anisotropic atmospheric turbulence is theoretically formulated by making use of the extended Huygens-Fresnel principle. Based on this formulation, a new closed-form expression for the mean square temporal width of Gaussian-beam-wave pulses passing horizontally through strong anisotropic atmospheric turbulence is developed. With the help of this expression, the increments of mean square temporal pulse width due to strong anisotropic atmospheric turbulence under various conditions are further calculated. Results show that the increment of mean square temporal pulse width due to strong anisotropic atmospheric turbulence is basically proportional to the effective anisotropic factor in most situations of interest, with the possible exception of cases in which both the Fresnel ratio and spectral index become relatively small; increasing the effective anisotropic factor can reduce the number of the said exceptions; the turbulence-induced increment of mean square temporal pulse width enlarges as the spectral index increases with a fixed value of the nondimensional turbulence-strength parameter. It is also illustrated that a significant enlargement in the turbulence-induced increment of mean square temporal pulse width occurs by changing the Fresnel ratio from a large to a tiny value if both the effective anisotropic factor and spectral index are relatively small.

New Cyclic Sparsity Measures for Deconvolution Based on Convex Relaxation

Periodic random impulse signals are powerful tools for various situations of interest and are a natural way for modeling highly localized events occurring randomly at given times. However, the measured impulses are often masked because of unwanted convolution and eventually drowned in noise. Thus, the resulting signal is not legible and may lead to poor or even erroneous analysis and, hence, the need of deconvolution to recover the random periodic impulses. As a matter of fact, periodic random impulse signals are sparse and the sparse coefficients are periodically correlated. It has thus emerged as to how to combine the data structure and the sparsity jointly for a best description. The originality of this study lies in the design of new measures of cyclic sparsity property for the deconvolution of signals that are simultaneously sparse and cyclostationary. To our knowledge, all related works in this field exploit only one property, either sparsity or cyclostationarity and never both properties together. The key feature of cyclic sparsity deconvolution is that it combines the cyclic structure and the sparsity together which implies a significantly enhanced performance. Finally, we include examples of computer simulations to illustrate the behavior in deconvolution context of the proposed algorithms against an $$\ell _1$$l1 sparse deconvolution through convex optimization. We show that deconvolution based on cyclic sparsity hypothesis increases the performance and reduces significantly the computation cost as well.

Asymptotic transversal stability for synchronized attractors in a metapopulation model

In this paper, we analyze the synchronization phenomenon for a discrete metapopulation model of multiple species with nonstationary and nonlinear coupling. The model is quite general, but we explore some particular situations of biological interest. In these cases, we obtain sufficient conditions for the transversal asymptotic stability of synchronized attractors. Some numerical results illustrate the theory. Copyright © 2015 John Wiley & Sons, Ltd

Linear stability analysis of a premixed flame with transverse shear

AbstractOne-dimensional planar premixed flames propagating in a uniform flow are susceptible to hydrodynamic instabilities known (generically) as Darrieus–Landau instabilities. Here, we extend that hydrodynamic linear stability analysis to include a lateral shear. This generalization is a situation of interest for laminar and turbulent flames when they travel into a region of shear (such as a jet or shear layer). It is shown that the problem can be formulated and solved analytically and a dispersion relation can be determined. The solution depends on a shear parameter in addition to the wavenumber, thermal expansion ratio, and Markstein lengths. The study of the dispersion relation shows that perturbations have two types of behaviour as wavenumber increases. First, for small shear, we recover the Darrieus–Landau results except for a region at small wavenumbers, large wavelengths, that is stable. Initially, increasing shear has a stabilizing effect. But, for sufficiently high shear, the flame becomes unstable again and its most unstable wavelength can be much smaller than the Markstein length of the zero-shear flame. Finally, the stabilizing effect of low shear can make flames with negative Markstein numbers stable within a band of wavenumbers.

Constrained Maximum Likelihood Estimation of the Abundances of Protein Conformation in a Heterogeneous Structural Ensemble from Small Angle X-ray Scattering Intensity Measurements

A method is described for maximum likelihood estimation (MLE) of the relative abundances of different conformations of a protein in a heterogeneous mixture based on small angle X-ray scattering (SAXS) intensities.This approach is of particular interest in situations where there are unknown, intermediate conformations, for instance, during catalytic cycling of a protein. First, an ensemble of structures is generated using molecular dynamics, crystallography or other technique. This ensemble is then clustered into sub-sets based on k-means clustering and the Cramer-Rao bound on the mixture coefficient estimation error. A sparse basis set that represents the space spanned by the measured SAXS intensities of the conformations of a protein is then generated from representative members of each cluster. Based on a statistical model for the intensity measurements, we show that the MLE approach can be expressed as a constrained convex optimization problem. Starting with a basis set generated from known conformations of the enzyme, adenylate kinase (ADK), we carried out Monte Carlo simulations to assess the performance of the proposed estimation scheme. We demonstrate the utility of the approach by identification of dominant conformations under different solution conditions and provide estimates of the abundance of minor species as a function of concentration of different ligands.