Helicity of convective flows from localized heat source in a rotating layer

Experimental and numerical study of the steady-state cyclonic vortex from isolated heat source in a rotating fluid layer is described. The structure of laboratory cyclonic vortex is similar to the typical structure of tropical cyclones from observational data and numerical modelling including secondary flows in the boundary layer. Differential characteristics of the flow were studied by numerical simulation using CFD software FlowVision. Helicity distribution in rotating fluid layer with localized heat source was analysed. Two mechanisms which play role in helicity generation are found. The first one is the strong correlation of cyclonic vortex and intensive upward motion in the central part of the vessel. The second one is due to large gradients of velocity on the periphery. The integral helicity in the considered case is substantial and its relative level is high

Quality of the Solution Sets of Parameter-Dependent Interval Linear Systems

Introduction By R , R denote the set of real vectors with n components, resp. the set of real n matrices. The set of all real compact intervals [a] := [a, a] := {a # a} is denoted by IR. We assume the reader is familiar with interval arithmetic [1]. By IR , IR denote the sets of interval n-vectors, resp. n matrices. Consider the linear system x = b(p), (1) where A(p) and b(p) depend a#ne-linearly on a parameter vector p . When p varies within a range [p] , the set of solutions to all A(p) x = b(p), p [p], called parametric solution set, is := # (A(p), b(p), [p]) := x = b(p) for some p [p]} . Denote by [A] = [A, A] := A([p]) , resp. [b] = [b, b] := b([p]) the interval matrix, resp. the interval vector, obtained from A(p), resp. b(p), substituting p by [p] and performing the corresponding interval operations. Hence the interval linear system x = [b], that is A([p]) x = b([p]) is a general non-parametric interval l

Effects of picrotoxin on light adapted frog electroretinogram are not due entirely to its action in proximal retina

AbstractIn order to evaluate the site of action of picrotoxin (antagonist of ionotropic GABA receptors) on the electroretinographic (ERG) b- and d-waves, in this study we compared its effects on the intensity–response function of the ERG waves in intact light adapted frog eyecup preparations with its effects in eyecups, where the activity of proximal neurons was blocked by 1mMN-methyl-d-aspartate (MNDA). Picrotoxin markedly enhanced the b- and d-wave amplitude and slowed the time course of the responses at all stimulus intensities in the intact eyecups. Perfusion with NMDA alone caused significant enhancement of the b-wave amplitude and diminution of the d-wave amplitude without altering their time course in the entire intensity range. When picrotoxin was applied in combination with NMDA, an enhancement of the b-wave amplitude and slowing of its time course were observed at all stimulus intensities. The increase of the b-wave amplitude was significantly higher than that seen in NMDA group. Combined application of picrotoxin and NMDA caused an enhancement of the d-wave amplitude at the lower stimulus intensities and its diminution at the higher ones, while the d-wave time course was delayed over the entire intensity range. The results obtained indicate that a part of picrotoxin effects on the amplitude and time course of the photopic ERG b- and d-waves are due to its action in the distal frog retina

New programs for determining the main parameters of open clusters

A set of computer programs for the determination of the main parameters of open clusters, such as color excess, distance, and age, is developed. The set consists of two units. The first unit is designed to search for open clusters in wide fields using JHKs-photometry from various catalogs (2MASS, UKIDSS, VISTA) by identifying areas of high stellar density. The second unit determines the parameters of open clusters by fitting photometric diagrams. This is the unit described in the paper. Probable cluster members are identified by the proximity to the basic sequences on the J-(J - H) and Q-(J - H) diagrams. The color excess is determined by minimizing the deviations of Q values on the Q-(J - H) diagram. Ages and distance moduli are determined by comparing the color-magnitude diagrams with theoretical isochrones. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Peculiarity of stellar kinematics in the solar vicinity

The peculiar velocities of nearby stars are studied. We determine the solar velocity components from the radial velocities and proper motions of stars and open clusters. We show that nearby stars are not very suitable for the determination of the solar motion components because of peculiarities in their velocity distribution. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Получение пористых полимерных композитов

В данной работе мы экспериментально убедились в целесообразности использования метода прессования форм из композита с примесью NaCl с последующим удалением соли для получения пористой структуры композитов