Stages of steady diffusion growth of a gas bubble in strongly supersaturated gas-liquid solution

Gas bubble growth as a result of diffusion flux of dissolved gas molecules from the surrounding supersaturated solution to the bubble surface is studied. The condition of the flux steadiness is revealed. A limitation from below on the bubble radius is considered. Its fulfillment guarantees the smallness of fluctuation influence on bubble growth and irreversibility of this process. Under the conditions of steadiness of diffusion flux three stages of bubble growth are marked out. With account for Laplace forces in the bubble intervals of bubble size change and time intervals of these stages are found. The trend of the third stage towards the self-similar regime of the bubble growth, when Laplace forces in the bubble are completely neglected, is described analytically.Comment: 22 page

Анализ энергетических затрат на поддержание конфигурации спутниковой группы типа TerraSAR-X - TanDEM-X

The maintenance of a given configuration of the satellite formation of the “TerraSAR-X - TanDEM-X” type is considered. It is assumed that the master satellite performs only maneuvers to maintain the working orbit, and the slave satellite performs identical maneuvers to maintain the working orbit and additionally performs maneuvers to maintain a given relative configuration of the group. For the working orbit of the master satellite, the dependence of the total characteristic velocity costs for maintaining a large semi-axis, eccentricity, inclination, and their various combinations on the maintenance accuracy is studied. The minimum limits of accuracy at which maneuvering is not required are set for each of the elements. This study is general in nature and allows future missions to be planned, providing the necessary trade-offs between the accuracy of maintenance and the total characteristic speed costs that increase as maintenance accuracy increases. Also, a study of the energy costs of relative maintenance, provided that the engines of the master and slave satellites operate almost the same. It is shown that the relative maintenance requires significantly lower fuel costs, even with the accuracy required in the project. The software product developed for this study is of universal application and will be used to investigate the cost of maintaining a more complex system of four satellites, in which three satellites rotate relative to the base satellite.Рассмотрено поддержание заданной конфигурации спутниковой группы типа TerraSAR-X - TanDEM-X. Предполагается, что ведущий спутник выполняет только маневры поддержания рабочей орбиты, а ведомый спутник совершает идентичные маневры для поддержания рабочей орбиты и дополнительно выполняет маневры, обеспечивающие поддержание заданной относительной конфигурации группы. Для рабочей орбиты ведущего спутника исследована зависимость затрат суммарной характеристической скорости на поддержание в заданных диапазонах большой полуоси, эксцентриситета, наклонения и их различных сочетаний от точности поддержания. Установлены минимальные границы точности поддержания по каждому из элементов, при которых маневрирование не требуется. Данное исследование носит общий характер и позволяет спланировать будущие миссии, обеспечив необходимый компромисс между точностью поддержания и затратами суммарной характеристической скорости, которые растут при повышении точности поддержания. Также проведено исследование затрат на относительное поддержание при условии, что двигатели у ведущего и ведомого спутников работают практически одинаково. Показано, что относительное поддержание требует существенно меньших затрат топлива, даже при точностях, требуемых в проекте. Разработанный для данного исследования программный продукт имеет универсальное применение и будет использован для исследования затрат на поддержание более сложной системы из четырех спутников, в которой три спутника вращаются относительно базового спутника

Полиморфизм и полифункциональность антигенов АВО системы крови

Group antigens of red blood cells are not only markers of blood groups, but also have different functions: receptor, transport, regulatory, trophic, immune, etc. The human genome has a gene locus ABO, which determines the blood group and regulates synthesis of the corresponding antigens. Genes A and B do not produce antigens directly, and their direct products are enzymes - glycosyltransferases. Transferases are able to attach the respective residues of glucose to the H-antigen galactose, thereby forming antigens A, B or AB. A and B antigens are heterogeneous in their structure and can be manifested in a number of different allotype. The main feature of the ABO system is the presence of natural antibodies to the missing red blood cell's antigen in plasma. In the interaction of antigen with antibody, both compounds exert mutual influence on their own conformation.Групповые антигены эритроцитов являются не только маркерами групп крови, но и выполняют различные функции: рецепторную, транспортную, регуляторную, трофическую, иммунную и др. В геноме человека имеется генный локус АВО, определяющий группу крови и отвечающий за синтез соответствующих антигенов. Гены А и В не продуцируют непосредственно антигены, их прямыми продуктами являются ферменты - гликозилтрансферазы. Трансферазы, кодируемые генами А и В, способны присоединять соответствующие остатки сахара к галактозе Н-антигена, являющегося для них исходным материалом, тем самым формируя антигены А, В или АВ. Антигены А и В неоднородны по своей структуре и могут проявляться в ряде различных аллотипов. Особенность системы АВО заключается в наличии в плазме крови естественных антител к отсутствующему на собственных эритроцитах антигену. При взаимодействии антигена с антителом оба соединения оказывают взаимное влияние на собственную пространственную конформацию

Radioheliograph observations of microwave bursts with zebra structures

The so-called zebra structures in radio dynamic spectra, specifically their frequencies and frequency drifts of emission stripes, contain information on the plasma parameters in the coronal part of flare loops. This paper presents observations of zebra structures in a microwave range. Dynamic spectra were recorded by Chinese spectro-polarimeters in the frequency band close to the working frequencies of the Siberian Solar Radio Telescope. The emission sources are localized in the flare regions, and we are able to estimate the plasma parameters in the generation sites using X-ray data. The interpretation of the zebra structures in terms of the existing theories is discussed. The conclusion has been arrived that the preferred generation mechanism of zebra structures in the microwave range is the conversion of plasma waves to electromagnetic emission on the double plasma resonance surfaces distributed across a flare loop.Comment: 18 pages, 7 figure

Normal transport properties for a classical particle coupled to a non-Ohmic bath

We study the Hamiltonian motion of an ensemble of unconfined classical particles driven by an external field F through a translationally-invariant, thermal array of monochromatic Einstein oscillators. The system does not sustain a stationary state, because the oscillators cannot effectively absorb the energy of high speed particles. We nonetheless show that the system has at all positive temperatures a well-defined low-field mobility over macroscopic time scales of order exp(-c/F). The mobility is independent of F at low fields, and related to the zero-field diffusion constant D through the Einstein relation. The system therefore exhibits normal transport even though the bath obviously has a discrete frequency spectrum (it is simply monochromatic) and is therefore highly non-Ohmic. Such features are usually associated with anomalous transport properties

Ultra-high energy cosmic ray investigations by means of EAS muon density measurements

A new approach to investigations of ultra-high energy cosmic rays based on the ground-level measurements of the spectra of local density of EAS muons at various zenith angles is considered. Basic features of the local muon density phenomenology are illustrated using a simple semi-analytical model. It is shown that muon density spectra are sensitive to the spectrum slope, primary composition, and to the features of hadronic interaction. New experimental data on muon bundles at zenith angles from 30 degrees to horizon obtained with the coordinate detector DECOR are compared with CORSIKA-based simulations. It is found that measurements of muon density spectra in inclined EAS give possibility to study characteristics of primary cosmic ray flux in a very wide energy range from 10^15 to 10^19 eV.Comment: 7 pages, 7 figures. Presented at CRIS-2006, Catania, Italy, May 29 - June 2, 2006. Accepted for publication in Nucl. Phys. B (Proc. Suppl.

РОЛЬ ГЕНА α2β-АДРЕНОРЕЦЕПТОРА В РАЗВИТИИ НАРУШЕНИЙ ВНУТРИЖЕЛУДОЧКОВОЙ ПРОВОДИМОСТИ

Background: The purpose of this study was to investigate association between the genetic polymorphism I/D of gene α2β-adrenoreceptor (ADRA2B) and hereditary disorders of ventricular conduction. Patients and methods: In this study, 102 people with complete left bundle branch block (45,71±1,852 years) — 46 females and 56 males, and 86 people with complete right bundle branch block (34,59±1,86 years) — 41 females and 45 males. The study was approved by Ethic Committee of the KrasSMU. All participants were included in the study after written informed consent form. Cardiological examination included clinical examination, electrocardiography, echocardiography, Holter monitoring, stresstest, koronaroangiografy and radionuclide method of a myocardium and molecular and genetic researches. Results: Statistically, significant prevalence of a homozygous genotype of DD on rare allele gene ADRA2B in both groups in comparison with group of control is established. The reliable dominance of the homozygous rare genotypes (D allele) of gene ADRA2B were detected in all groups. Conclusion: Polymorphism DD of a gene ADRA2B is a genetic predictor of predisposition to the blockade of the right and left bundle branch block.Цель исследования: изучить ассоциацию I/D-полиморфизма гена α2β-адренорецептора (ADRA2B) с первичными нарушениямивнутрижелудочковой проводимости. Пациенты и методы: в исследование были включены лица с наследственными нарушениями внутрижелудочковой проводимости. Обследовано 102 человека с нарушением проводимости по левой ножке пучка Гиса (45,71±1,85 лет; 46 женщин и 56 мужчин) и 86 — с нарушением проводимости по правой ножке пучка Гиса (34,59±1,86 лет; 41 женщина и 45 мужчин). Научное исследование одобрено Этическим комитетом КрасГМУ. Всем обследуемым с нарушениями сердечной проводимости было проведено клинико-инструментальное исследование по следующей программе: клинический осмотр, электро- и эхокардиография, холтеровское мониторирование, велоэргометрия, коронароангиография и сцинтиграфия миокарда, молекулярно-генетические исследования. Результаты: установлено статистически значимое преобладание гомозиготного генотипа DD по редкому аллелю гена ADRA2B в обеих группах по сравнению с группой контроля. Выводы: полиморфизм DD гена ADRA2B является генетическим предиктором предрасположенности к возникновению полной блокады правой и левой ножки пучка Гиса

A new approach for the limit to tree height using a liquid nanolayer model

Liquids in contact with solids are submitted to intermolecular forces inferring density gradients at the walls. The van der Waals forces make liquid heterogeneous, the stress tensor is not any more spherical as in homogeneous bulks and it is possible to obtain stable thin liquid films wetting vertical walls up to altitudes that incompressible fluid models are not forecasting. Application to micro tubes of xylem enables to understand why the ascent of sap is possible for very high trees like sequoias or giant eucalyptus.Comment: In the conclusion is a complementary comment to the Continuum Mechanics and Thermodynamics paper. 21 pages, 4 figures. Continuum Mechanics and Thermodynamics 20, 5 (2008) to appea

New technique and results of cosmic ray investigations in the energy interval 1015–1019 eV

New technique of EAS investigations based on the measurements of local muon density spectra (LMDS) is developed. Application of this method to investigations of inclined EAS allows exploration of CR energy interval from 10 15 to 10 19 eV by means of a relatively small detector with area ∼100m 2 due to very strong dependence of EAS muon density on zenith angle. During 2002-2007, long-term NEVOD- DECOR experiment (about 20,000h live time) was conducted, and more than two million muon bundles in zenith angle interval 30-88 degrees were registered. Comparison of experimental data with results of CORSIKA-based simulations showed that the new method is sensitive to all main peculiarities of CR energy spectrum: the knee, increase of the energy spectrum slope with energy, the second knee. But the observed progressive excess of muon bundles with the increase of primary CR energy in comparison with simulations (even for pure iron composition) can indicate the appearance of new processes of muon generation. In this case, for correct investigations of EAS, the experimental arrays must be supplemented by detectors which can measure or evaluate the energy of muons

Spectral Measurement of Photon Emission from Individual Gold Nanoparticles Using Scanning Tunneling Microscopy

The light emission spectra of individual Au nanoparticles induced by a scanning tunneling microscope (STM) have been investigated. Two-dimensional ensembles of tunnel-coupled Au particles were prepared by thermal evaporation onto a native oxide silicon wafer in ultrahigh vacuum (10 – 9 mbar). Our STM measurements show a single peak at photon energy 1.6 eV in the tunneling mode and two peaks at 2.2 eV (connected with the Mie plasmon) and 1.45 eV (a new peak which was not discussed in literature before) in the field emission mode