Selfgravitating Gas Spheres in a Box and Relativistic Clusters: Relation between Dynamical and Thermodynamical Stability

We derive a variational principle for the dynamical stability of a cluster as a gas sphere in a box. Newtonian clusters are always dynamically stable and, for relativistic clusters, the relation between dynamical and thermodynamical instabilities is analyzed. The boundaries between dynamically and thermodynamically stable and unstable models are found numerically for relativistic stellar systems with different cut off parameters. A criterion based on binding energy curve is used for determination of the boundary of dynamical stability.Comment: 10 figure

Effect of angular momentum distribution on gravitational loss-cone instability in stellar clusters around massive BH

Small perturbations in spherical and thin disk stellar clusters surrounding massive a black hole are studied. Due to the black hole, stars with sufficiently low angular momentum escape from the system through the loss cone. We show that stability properties of spherical clusters crucially depend on whether the distribution of stars is monotonic or non-monotonic in angular momentum. It turns out that only non-monotonic distributions can be unstable. At the same time the instability in disk clusters is possible for both types of distributions.Comment: 14 pages, 7 figures, submitted to MNRA

Scaling behavior in a stochastic self-gravitating system

A system of stochastic differential equations for the velocity and density of a classical self-gravitating matter is investigated by means of the field theoretic renormalization group. The existence of two types of large-scale scaling behavior, associated to physically admissible fixed points of the renormalization-group equations, is established. Their regions of stability are identified and the corresponding scaling dimensions are calculated in the one-loop approximation (first order of the epsilon expansion). The velocity and density fields have independent scaling dimensions. Our analysis supports the importance of the rotational (nonpotential) components of the velocity field in the formation of those scaling laws.Comment: 6 pages, REVTEX3 source, 1 PS figur

Dark quark domains

Formation of stable domains filled with strongly correlated coherent quark matter is discussed in general terms and is exemplified further in the framework of the Generalised Nambu-Jona-Lasinio model. It is argued that such domains, if exist in the Universe, appear dark to an external observer.Comment: LaTeX2e, 5 pages, uses jetpl.cls (included), to appear in JETP Let

Giant magneto-optical anisotropy in Fe/Au monoatomic multilayer

Abstract A giant magneto-optical anisotropy (MOA) in a magnetic monoatomic Fe/Au multilayer structure is reported. The dependence of the off-diagonal part of the optical conductivity tensor on the angle between the magnetization and crystallographic axes is evidenced by measurements of both the polar and longitudinal Kerr effects. The microscopic origin of the MOA is elucidated on the basis of the first principles' band-structure calculations. A relationship of the MOA with the predicted strong anisotropy of Fe d orbital magnetic moment and the magnetocrystalline anisotropy is discussed.

Types of injuries and first aid in case of fires on the example of the tragedy in the Lame horse club

The article discusses one of the largest fire victims in Russia in terms of the number of victims. Types of lesions and first aidВ статье рассмотрен один из крупнейших по числу жертв пожар в России. Виды поражений и оказание первой медицинской помощи

Chemical exploration and identification of the causes of chemical accidents

The article deals the relevance of chemical exploration, its goals and objectives, as well as the main causes of chemical accidentsВ статье рассмотрены актуальность химической разведки, её цели и задачи, а также основные причины химических авари

Нозокомиальная инфекция у пациентов с тяжелым и крайне тяжелым течением COVID-19

The aim of the study was to determine the etiology and frequency of nosocomial infections in patients with severe and critical COVID-19.Material and methods. A retrospective, single-center study included 168 patients with COVID-19 admitted to the intensive care unit (ICU). All episodes of infection, clinical and laboratory characteristics, and outcome were documented in patients.Results. Hospital-acquired infections were detected in 82 (48.8%) of 168 patients, more frequently in men (p = 0.028).  A total of 232 episodes of nosocomial infections were observed including ventilator-associated pneumonia (48.2%), bloodstream infection (39.2%), nosocomial pneumonia/tracheobronchitis (13.4%), and urinary tract infection (5.2%). The main causative agents of nosocomial infections were resistant strains of Acinetobacter baumannii and Klebsiella pneumoniae. Infections developed on the average on day 6 [3; 9] of ICU stay and were associated with the initial severity of the patients assessed by SOFA (p=0.016), SpO2 (p=0.005), lymphopenia severity (p=0.003), Neutrophil-Lymphocyte Ratio (p=0.004), C-reactive protein (p=0.01), aspartate aminotransferase (AST) level (p=0.022), or vitamin D (p=0.035) levels. Patients diagnosed with infection were more likely than those without infections to require mechanical ventilation (67.6% vs 32.4%, p < 0.001), high-flow oxygen therapy (50.0% vs 31.0%, p = 0.020), renal replacement therapy (36.8% vs 9.3%, p = 0.003), and had longer ICU length of stay (13 [9; 18] vs 4 [2; 8], p < 0.001), hospital length of stay (19 [14; 29] vs 15 [11; 20], p = 0.001) and mortality (47 (57.3%) vs 25 (29.0%), p < 0.001).Conclusion. In patients with severe and critical COVID-19 a high incidence of nosocomial infections was found, which negatively affected the outcome. In more than half of the cases, the infection was caused by resistant strains of Gram-negative bacilli. Procalcitonin is a useful biomarker for identifying bacterial infection in patients with COVID-19.Цель исследования. Определить этиологию и частоту внутрибольничной инфекции у пациентов с тяжелым и крайне тяжелым течением COVID-19.Материалы и методы. В ретроспективное одноцентровое исследование включили 168 пациентов с COVID-19, госпитализированных в отделение реанимации и интенсивной терапии (ОРИТ). У пациентов регистрировали все случаи инфекции, клинико-лабораторную характеристику и исход.Результаты. Внутрибольничную инфекцию выявили у 82 (48,8%) из 168 пациентов, чаще у мужчин (р=0,028). Всего регистрировали 232 эпизода внутрибольничной инфекции: вентилятор-ассоциированную пневмонию (48,2%), инфекцию кровотока (39,2%), внутрибольничную пневмонию/трахеобронхит (13,4%) и мочевую инфекцию (5,2%). Основными возбудителями внутрибольничной инфекции были резистентные штаммы Acinetobacter baumannii и Klebsiella pneumoniae. Инфекция развивалась в среднем на 6-й [3; 9] день нахождения в ОРИТ, была ассоциирована с исходной тяжестью состояния, определяемой по ряду параметров: SOFA (p=0,016), SpO2 (p=0,005), выраженности лимфопении (p=0,003), нейтрофильно-лимфоцитарному соотношению (p=0,004), концентрации С-реактивного белка (p=0,01), аспартаминтрансферазы (p=0,022), витамина Д (p=0,035). Пациенты, у которых была диагностирована инфекция, в сравнении с пациентами без инфекции, чаще нуждались в проведении искусственной вентиляции легких (67,6 и 32,4%, p<0,001), высокопоточной кислородотерапии (50,0 и 31,0%, p=0,020), заместительной почечной терапии (36,8 и 9,3%, p=0,003), имели большую продолжительность нахождения в ОРИТ (13 [9; 18] и 4 [2; 8], p<0,001), большую продолжительность пребывания в стационаре (19 [14; 29] и 15 [11; 20], p=0,001) и летальность (47 (57,3%) и 25 (29,0%), p<0,001).Заключение. У пациентов с тяжелым и крайне тяжелым течением COVID-19 выявили высокую частоту внутрибольничной инфекции, которая негативно влияла на исход заболевания. Более чем в половине случаев возбудителями инфекции являлись резистентные штаммы грамотрицательных палочек. Прокальцитонин является полезным биомаркером для идентификации бактериальной ин-фекции у пациентов с COVID-19