Electron-phonon induced spin relaxation in InAs quantum dots

We have calculated spin relaxation rates in parabolic quantum dots due to the phonon modulation of the spin-orbit interaction in presence of an external magnetic field. Both, deformation potential and piezoelectric electron-phonon coupling mechanisms are included within the Pavlov-Firsov spin-phonon Hamiltonian. Our results have demonstrated that, in narrow gap materials, the electron-phonon deformation potential and piezoelectric coupling give comparable contributions as spin relaxation processes. For large dots, the deformation potential interaction becomes dominant. This behavior is not observed in wide or intermediate gap semiconductors, where the piezoelectric coupling, in general, governs the spin relaxation processes. We also have demonstrated that spin relaxation rates are particularly sensitive to the Land\'e $g$-factor.Comment: 4 pages, 2 figures, to be appear in Physica E: Proceedings of the 11 International Conference on Narrow Gap Semiconductor

On generating functions in the AKNS hierarchy

It is shown that the self-induced transparency equations can be interpreted as a generating function for as positive so negative flows in the AKNS hierarchy. Mutual commutativity of these flows leads to other hierarchies of integrable equations. In particular, it is shown that stimulated Raman scattering equations generate the hierarchy of flows which include the Heisenberg model equations. This observation reveals some new relationships between known integrable equations and permits one to construct their new physically important combinations. Reductions of the AKNS hierarchy to ones with complex conjugate and real dependent variables are also discussed and the corresponding generating functions of positive and negative flows are found. Generating function of Whitham modulation equations in the AKNS hierarchy is obtained.Comment: 11 pages, no figure

On Whitham theory for perturbed integrable equations

Whitham theory of modulations is developed for periodic waves described by nonlinear wave equations integrable by the inverse scattering transform method associated with $2\times2$ matrix or second order scalar spectral problems. The theory is illustrated by derivation of the Whitham equations for perturbed Korteweg-de Vries equation and nonlinear Schr\"odinger equation with linear damping.Comment: 17 pages, no figure

Technological accelerator with closed electron drift for surface treatment

Now the technologies of functional covers deriving on large surfaces intensively are developed. For these purposes the plasma sputtering systems of magnetron, vacuum - arc, electron -beam and other types are effectively used. The quality of cover largely depends on preliminary treatment of a surface - its clearing and activation. In the paper is shown, that the anode layer thruster (or the anode layer accelerator – ALA) intensively cleans a surface of target body in a narrow pressure range of working gas in a system. On absolute rate of cleaning (~ 1 nm/s) ALA do not concede to a Kaufman sources. The injection of gas in the accelerator through electrodes with success can be replaced by injection immediately in volume. In this case the rates of sputtering increase approximately twice. The optimal pressure for cleaning essentially will increase, that does ALA compatible with a magnetron on pressure of working gases

Эластография в диагностике неалкогольной жировой болезни печени.

Currently, there has been a progressive increase in prevalence of one of the most common diffuse chronic liver diseases ― non-alcoholic fatty liver disease (NAFLD). Assessment of the stages of liver fibrosis and steatosis is prognostically significant in diagnosis of NAFLD. Routine diagnostic methods are either not able to accurately assess the severity of fibrosis and steatosis (ultrasound, laboratory tests), or cannot be used as a simple screening tool (liver biopsy) due to such limitations as invasiveness, dependence on pathologist qualification, high cost, and limited region of interest. Over the last two decades, the great progress has been made in non-invasive visualization of pathological changes in liver diseases. In this review, we examined the diagnostic characteristics of the most widely used non-invasive imaging methods in clinical practice, available for quantitative determination of fat and fibrosis in the liver: transient elastography with controlled attenuation parameter (CAP), acoustic radiation force impulse (ARFI) and shear wave elastography (SWE). Comparing these methods and their limitations, we came to conclusion, that elastographic methods (slightly more ARFI and SWE) are able to verify the F3, F4 stages of fibrosis in NAFLD with high sensitivity and specificity (90%); however, they are less accurate for early stages. Elastographic techniques have moderate accuracy in identifying the degree of steatosis due to the lack of uniform standardized cut-off values of CAP.В настоящее время наблюдается рост распространенности одного из самых часто встречающихся диффузных хронических заболеваний печени ― неалкогольной жировой болезни печени. Прогностически значимой в диагностике данного заболевания считается оценка стадий фиброза и стеатоза печени. Обычные методы диагностики либо не способны с высокой точностью оценить выраженность фиброза и стеатоза (ультразвуковое исследование, лабораторные тесты), либо не могут быть использованы в качестве простого скрининга (биопсия печени) вследствие своих ограничений (инвазивность, зависимость от квалификации морфолога, высокая стоимость, ограниченный участок исследования). За последние два десятилетия огромные успехи были достигнуты в неинвазивной визуализации патоморфологических изменений при болезнях печени. В этом обзоре мы изучили диагностические характеристики наиболее широко применяющихся в клинической практике неинвазивных методов визуализации, доступных для количественного определения жира и фиброза в печени: транзиентную эластографию с контролируемым параметром затухания (CAP), акустическое радиационное давление, эластографию сдвиговых волн. Сравнивая вышеперечисленные методы и их ограничения, мы пришли к выводу, что на сегодняшний день эластографические методы (немного в большей степени акустическое радиационное давление и эластография сдвиговых волн) способны с высокой чувствительностью и специфичностью (90%) верифицировать F3-, F4-стадии фиброза при неалкогольной жировой болезни печени, но менее достоверны в отношении ранних стадий. Степени стеатоза распознаются с умеренной точностью, что связано с отсутствием единых стандартизированных пороговых значений CAP

Study of electrophysical properties of beryllium ceramics with the addition of microand nanoparticles of titanium dioxide

In the present paper the research results of influence of nanoparticles TiO2 additions in the range 0,1 — 2,0 wt. % on electrophysical properties of oxide-beryllium ceramics (BeO + TiO2) made of micropowders are presented. The electrophysical characteristics of synthesized ceramics modified with 30 wt. % TiO2 microand nanoparticles in the electric current frequency range of 100 Hz — 100 MHz were studied by the total complex resistance method (impedance). It is known that the introduction of TiO2 addition to the BeOceramics after heat treatment in a reducing atmosphere is accompanied by a significant increase in electrical conductivity and the ability to absorb electromagnetic radiation in a wide range of frequencies. According to the results of the studies it was found that the addition of nanoparticles TiO2 into the (BeO + TiO2)-ceramics significantly reduces its static electrical resistance in comparison with the serial sample, and the specific conductivity of such ceramics significantly increases at high frequencies ~ 107 Hz. The addition of TiO2 nanoparticles significantly increases the dielectric losses of the sample sintered in the temperature range 1530 — 1550 °C. The values of real and imaginary parts of dielectric permittivity of such ceramics and the tangent of the angle of dielectric loss are two times higher compared to the serial sample — BT-30 (B — beryllium, T — titanium). The obtained results are unique in their kind, due to the experiment with a rare and strategically important material — beryllium oxide and the possibility of synthesizing new nanostructures based on it

Refraction of dispersive shock waves

We study a dispersive counterpart of the classical gas dynamics problem of the interaction of a shock wave with a counter-propagating simple rarefaction wave often referred to as the shock wave refraction. The refraction of a one-dimensional dispersive shock wave (DSW) due to its head-on collision with the centred rarefaction wave (RW) is considered in the framework of defocusing nonlinear Schr\"odinger (NLS) equation. For the integrable cubic nonlinearity case we present a full asymptotic description of the DSW refraction by constructing appropriate exact solutions of the Whitham modulation equations in Riemann invariants. For the NLS equation with saturable nonlinearity, whose modulation system does not possess Riemann invariants, we take advantage of the recently developed method for the DSW description in non-integrable dispersive systems to obtain main physical parameters of the DSW refraction. The key features of the DSW-RW interaction predicted by our modulation theory analysis are confirmed by direct numerical solutions of the full dispersive problem.Comment: 45 pages, 23 figures, minor revisio

Расчетное обоснование механической безопасности Конгресс-холла в Челябинске

Aims of research. The article is devoted to actual problems of computational analysis of stress-strain state, strength and stability of load-bearing structures with allowance for the main and special combinations of loads and impacts, comparison of the results of alternative structural analysis of unique cultural and business complex “Congress Hall” in Chelyabinsk. The natural conditions of the area of location of this object and main load-bearing structures of the object are described. Besides, characteristic and design loads, their combinations, formulation of objectives of computational research and methods of solution are presented. Methods. Space discretization and solution of the corresponding problems of mathematical (numerical) and computer modelling of the considering unique building were carried out with the use of finite element method. Detailed finite element models of the coupled system “combined foundation - loadbearing structures” and its fragments (subsystems) were developed and verified. They adequately reflect geometric-stiffness, inertial and load parameters of the object and the resulting stress-strain state. Progressive collapse analysis are under consideration as well. Licensed, certified and verified (by the Russian Academy of Architecture and Construction Sciences) finite element software package “ANSYS Mechanical” was used. Results. The resulting parameters of stress-strain state, strength and dynamics of load-bearing structures of the building with allowance for design (in accordance with design codes) combinations of vertical and wind loads are considered. Besides, information about results of progressive collapse analysis is presented. Thus, a reasonable conclusion is made about the reliability of the criterion parameters of strength, stability and dynamics of the load-bearing structures of the object.Цели. Статья посвящена актуальным вопросам расчетных исследований напряженно-деформированного состояния (НДС), прочности и устойчивости основания и несущих конструкций при основных и особых сочетаниях нагрузок и воздействий, сравнительного анализа результатов альтернативных расчетов уникального проектируемого объекта строительства - общественно-делового центра «Конгресс-холл» в Челябинске. Описаны природные условия района расположения здания, устройство комбинированного основания, фундаментов и несущих конструкций объекта, основные и особые нагрузки (расчетные и нормативные) и их сочетания, постановка задач расчетных исследований, инструментарий их решения и полученные результаты. Методы. Дискретизация по пространству и решение результирующих задач математического (численного) моделирования состояния объекта осуществлялись методом конечных элементов в перемещениях. Построены, разработаны и проверены подробные конечноэлементные модели системы «комбинированное основание - несущие конструкции здания» и отдельных подсистем, адекватно отражающие геометрико-жесткостные, инерционные и нагрузочные характеристики объекта и результирующее НДС, проанализирована устойчивость против прогрессирующего обрушения. Все основные расчеты проведены с использованием лицензионного конечноэлементного программного комплекса ANSYS Mechanical, верифицированного в Российской академии архитектуры и строительных наук (РААСН). Результаты. Рассмотрены результирующие параметры НДС, прочности и динамики основания и несущих конструкций объекта при нормативно-регламентированных сочетаниях вертикальных и ветровых нагрузок, а также результаты расчетов на устойчивость против прогрессирующего обрушения. В заключении делается обоснованный вывод о достоверности полученных расчетами критериальных параметров, определяющих прочность, устойчивость и динамику несущих конструкций объекта

Morphological features of the simulated gunshot wounds of rabbits’ soft tissues at different temperatures of injuring object

У статті представлені результати експериментального моделювання поверхневих осколкових вогнепальних поранень м'яких тканин, отриманих при малоенергетичних вогнепальних пораненнях. Вивчено патоморфоз вогнепальних поранень, зіставлені особливості та терміни їх загоєння залежно від температури уражаючих фрагментів. Метою роботи було вивчення впливу температури травмуючого осколка на процеси загоєння м'яких тканин експериментальних тварин з поверхневими осколковими вогнепальними пораненнями з низьким рівнем енергії. Використовуючи метод випадкових чисел, лабораторних тварин (кролики) розподілили на 3 експериментальні групи (по 15 тварин у кожній). У кожній групі травми наносилися осколками з різними температурами − 18°С, 50°С і 100°С. Контрольна група складалася з 10 інтактних тварин. На 14, 30 і 60 день по 5 тварин з кожної групи були виведені з експерименту. Мікроскопічне дослідження м'яких тканин проводилося з використанням світлового мікроскопа PRIMO STAR (Carl Zeiss, Німеччина) при збільшенні в 56 і 400 разів. При оцінці стану тканин у зоні пошкодження встановлено, що з підвищенням температури ранячого осколка спостерігається більш повільне заповнення грануляційною тканиною дефекту, що утворюється в процесі утилізації некротичного детриту. Висока температура ранячого осколка поряд з механічним розривом тканин викликає термічний коагуляційний некроз. Щільні коагульовані некротичні маси, що покривають рановий канал зсередини, не тільки збільшують обсяг некротичних мас, але й ускладнюють процес загоєння рани. При температурі ранячих осколків 100°C утворення некротичної кірки на поверхні рани відбувалося в середньому на 3±1,2 добу – пізніше, ніж при температурах 18°C і 50°C, найменш виражене загоєння відбувалося на дні рани і в м'язовій тканині. Мікроскопічно спостерігали некротичні, а не дистрофічні зміни міоцитів. Таким чином, порівняльний аналіз патоморфозу м'яких тканин у рані при пораненні з пневматичної гвинтівки MP-532 з різною температурою осколків показав відмінності як з боку альтерації тканин, так і з боку регенераторного потенціалу. The article presents the results of experimental modeling of superficial fragment gunshot wounds of soft tissues, obtained in low-energy gunshot wounds. The pathomorphosis of gunshot wounds was studied, and the features and timing of their healing were compared depending on the temperature of the damaging fragments. The aim of the work was to study the effect of the temperature of the injuring shrapnel on the healing processes of the soft tissues of experimental animals with superficial low-energy fragment gunshot wounds. Using the random number method, laboratory animals (rabbits) were divided into 3 experimental groups (15 animals each). In each group, wounding was with fragments with different temperatures − 18°С, 50°С and 100°С. The control group consisted of 10 intact animals. On day 14th, 30th and 60th, 5 animals from each group were withdrawn from the experiment. Microscopic examination of soft tissues was performed using a PRIMO STAR light microscope (Carl Zeiss, Germany) at magnification by 56 and 400 times. When assessing the state of tissues in the area of wound damage, it was established that as the temperature of the injuring fragment increases, a slower filling of the defect formed by the necrotic detritus in the process of utilization of necrotic detritus is observed. The high temperature of the injuring fragment along with the mechanical rupture of tissues causes thermal coagulation necrosis. Dense coagulated necrotic masses covering the wound canal from the inside, not only increase the volume of necrotic masses, but also complicate the process of wound healing. At a temperature of wounding fragments 100°C, the formation of a necrotic crust on the surface of the wound occurred on average 3±1.2 days later than at temperatures of 18°C and 50°C, the least pronounced healing took place at the bottom of the wound and in the muscle tissue. Microscopically necrotic, not dystrophic changes were observed in myocytes. Thus, a comparative analysis of the pathomorphosis of soft tissues in a wound when injured from an air rifle MP-532 with different temperature of the fragments showed differences from both the alteration of the tissues and the regenerative potential

Registration of atmospheric neutrinos with the Baikal neutrino telescope

We present first neutrino induced events observed with a deep underwater neutrino telescope. Data from 70 days effective life time of the BAIKAL prototype telescope NT-96 have been analyzed with two different methods. With the standard track reconstruction method, 9 clear upward muon candidates have been identified, in good agreement with 8.7 events expected from Monte Carlo calculations for atmospheric neutrinos. The second analysis is tailored to muons coming from close to the opposite zenith. It yields 4 events, compared to 3.5 from Monte Carlo expectations. From this we derive a 90 % upper flux limit of 1.1 * 10^-13 cm^-2 sec^-1 for muons in excess of those expected from atmospheric neutrinos with zenith angle > 150 degrees and energy > 10GeV.Comment: 20 pages, 11 figure