Thermal radiation of various gravitational backgrounds

We present a simple and general procedure for calculating the thermal radiation coming from any stationary metric. The physical picture is that the radiation arises as the quasi--classical tunneling of particles through a gravitational barrier. We show that our procedure can reproduce the results of Hawking and Unruh radiation. We also show that under certain kinds of coordinate transformations the temperature of the thermal radiation will change in the case of the Schwarzschild black holes. In addition we apply our procedure to a rotating/orbiting system and show that in this case there is no radiation, which has experimental implications for the polarization of particles in circular accelerators.Comment: 6 pages revtex, added references, publication version. To be published IJMP

Recursos léxicos de homônimos interlinguais em persa moderno, dari e tajik

The relevance of the researched problem is caused by the need to study the lexical features of these languages, and to show students of a real linguistic situation when studying the Persian language. The aim of the article is to consider the lexical features of interlingual homonyms in modern Persian, Dari and Tajik. The leading approach in the studying of this issue is a problem-thematic approach. The study of interlingual homonyms in terms of their features and the review of the situations in which they are used in the Persian and Tajik languages, shows the possible approaches to the description of their semantics [19, 281]. And at its queue this is a new direction in the modern Persian lexicography, which is of a great scientific benefit. The submissions of this article may be useful in the teaching of the modern Persian, Tajik, Dari languages as well as when lecturing on the lexicology and dialectology of Persian, Tajik, Dari.La relevancia del problema investigado se debe a la necesidad de estudiar las características léxicas de estos idiomas, y mostrar a los estudiantes una situación lingüística real al estudiar el idioma persa. El objetivo del artículo es considerar las características léxicas de los homónimos interlingüísticos en persa, dari y tayiko modernos. El enfoque principal en el estudio de este tema es un enfoque temático de problemas. El estudio de los homónimos interlingüísticos en términos de sus características y la revisión de las situaciones en las que se utilizan en las lenguas persa y tayika, muestra los posibles enfoques para la descripción de su semántica [19, 281]. Y en su cola esta es una nueva dirección en la lexicografía persa moderna, que es de gran beneficio científico. Las presentaciones de este artículo pueden ser útiles en la enseñanza de los idiomas persa, tayiko y dari modernos, así como para dar conferencias sobre lexicología y dialectología del persa, tayiko y dari.A relevância do problema pesquisado deve-se à necessidade de estudar as características lexicais dessas línguas, e de mostrar aos alunos uma situação lingüística real no estudo da língua persa. O objetivo do artigo é considerar as características lexicais dos homônimos interlinguísticos no persa, dari e tadjique modernos. A abordagem principal no estudo desta questão é uma abordagem problema-temática. O estudo dos homônimos interlinguísticos em termos de suas características e a revisão das situações em que são usados nas línguas persa e tadjique, mostra as abordagens possíveis para a descrição de sua semântica [19, 281]. E em sua fila esta é uma nova direção na lexicografia persa moderna, que é de grande benefício científico. As submissões deste artigo podem ser úteis no ensino das línguas persa, tadjique e dari modernas, bem como nas palestras sobre lexicologia e dialetologia persa, tadjique e dari

How often does the Unruh-DeWitt detector click? Regularisation by a spatial profile

We analyse within first-order perturbation theory the instantaneous transition rate of an accelerated Unruh-DeWitt particle detector whose coupling to a massless scalar field on four-dimensional Minkowski space is regularised by a spatial profile. For the Lorentzian profile introduced by Schlicht, the zero size limit is computed explicitly and expressed as a manifestly finite integral formula that no longer involves regulators or limits. The same transition rate is obtained for an arbitrary profile of compact support under a modified definition of spatial smearing. Consequences for the asymptotic behaviour of the transition rate are discussed. A number of stationary and nonstationary trajectories are analysed, recovering in particular the Planckian spectrum for uniform acceleration.Comment: 30 pages, 1 figure. v3: Added references and minor clarification

Observer Dependent Horizon Temperatures: a Coordinate-Free Formulation of Hawking Radiation as Tunneling

We reformulate the Hamilton-Jacobi tunneling method for calculating Hawking radiation in static, spherically-symmetric spacetimes by explicitly incorporating a preferred family of frames. These frames correspond to a family of observers tied to a locally static timelike Killing vector of the spacetime. This formulation separates the role of the coordinates from the choice of vacuum and thus provides a coordinate-independent formulation of the tunneling method. In addition, it clarifies the nature of certain constants and their relation to these preferred observers in the calculation of horizon temperatures. We first use this formalism to obtain the expected temperature for a static observer at finite radius in the Schwarzschild spacetime. We then apply this formalism to the Schwarzschild-de Sitter spacetime, where there is no static observer with 4-velocity equal to the static timelike Killing vector. It is shown that a preferred static observer, one whose trajectory is geodesic, measures the lowest temperature from each horizon. Furthermore, this observer measures horizon temperatures corresponding to the well-known Bousso-Hawking normalization.Comment: 11 pages, 1 2-part figure, references added, appendix added, discussion streamline

COMPARISON OF THE STRUCTURE AND FRACTURES OF HARD ALLOYS

Проблему импортозамещения твердых сплавов для наплавок рабочих органов сельскохозяйственных машин невозможно решить без создания новых отечественных твердосплавных материалов. Решение такой задачи возможно только при условии достижения необходимой глубины понимания природы прочности, износостойкости и сопротивляемости разрушению существующих твердых сплавов, механизмов разрушения наблюдаемых в них разнородных структур.The problem of import substitution of hard alloys for pad weld work tool of agricultural machinery is impossible to solve without creation new domestic hard-alloy material. The solution of such task is possible only in condition of achievement of necessary depth of understanding of the nature of durability, wear resistance and the resilience to destruction of the existing solid alloys, mechanisms of destruction of the diverse structures observed in them.Работа выполнена в рамках Соглашения № 14.578.21.0129 о предоставлении субсидии для финансового обеспечения (возмещения) затрат, связанных с выполнением ПНИЭР по теме: «Разработка импортозамещающих твердых сплавов с повышенными износными и технологическими характеристиками для упрочнения быстроизнашиваемых деталей сельхозмашин, эксплуатирующихся в абразивной среде». Уникальный идентификатор ПНИЭР RFMEFI57815X0129

Black Hole Evaporation in a Noncommutative Charged Vaidya Model

The aim of this paper is to study the black hole evaporation and Hawking radiation for a noncommutative charged Vaidya black hole. For this purpose, we determine spherically symmetric charged Vaidya model and then formulate a noncommutative Reissner-Nordstr$\ddot{o}$m-like solution of this model which leads to an exact $(t-r)$ dependent metric. The behavior of temporal component of this metric and the corresponding Hawking temperature is investigated. The results are shown in the form of graphs. Further, we examine the tunneling process of the charged massive particles through the quantum horizon. It is found that the tunneling amplitude is modified due to noncommutativity. Also, it turns out that black hole evaporates completely in the limits of large time and horizon radius. The effect of charge is to reduce the temperature from maximum value to zero. It is mentioned here that the final stage of black hole evaporation turns out to be a naked singularity.Comment: 25 pages, 36 figures, accepted for publication in J. Exp. Theor. Phy

Back reaction, emission spectrum and entropy spectroscopy

Recently, an interesting work, which reformulates the tunneling framework to directly produce the Hawking emission spectrum and entropy spectroscopy in the tunneling picture, has been received a broad attention. However, during the emission process, most related observations have not incorporated the effects of back reaction on the background spacetime, whose derivations are therefore not the desiring results for the real physical process. With this point as a central motivation, in this paper we suitably adapt the \emph{reformulated} tunneling framework so that it can well accommodate the effects of back reaction to produce the Hawking emission spectrum and entropy spectroscopy. Consequently, we interestingly find that, when back reaction is considered, the Parikh-Wilczek's outstanding observations that, an isolated radiating black hole has an unitary-evolving emission spectrum that is \emph{not} precisely thermal, but is related to the change of the Bekenstein-Hawking entropy, can also be reproduced in the reformulated tunneling framework, meanwhile the entropy spectrum has the same form as that without inclusion of back reaction, which demonstrates the entropy quantum is \emph{independent} of the effects of back reaction. As our final analysis, we concentrate on the issues of the black hole information, but \emph{unfortunately} find that, even including the effects of back reaction and higher-order quantum corrections, such tunneling formalism can still not provide a mechanism for preserving the black hole information.Comment: 16 pages, no figure, use JHEP3.cls. to be published in JHE

Хронические вирусные гепатиты B и D у беременных: распространенност ь, течение и исходы (обзор литературы)

Hepatitis B is most common among young people, which is explained by the ways of infection – parenteral, sexual and vertical. Mother-to-child transmission is the main route of infection for children in areas where the hepatitis B virus (HBV) is endemic.The available current data on the course and outcomes of chronic viral hepatitis B are contradictory in pregnant women. Some authors argue that the exacerbation of chronic hepatitis B is more common in the first and third trimesters in pregnant women, and with an increase in gestation, there is a deterioration in liver function and an increased risk of fulminant liver failure. Other researchers note a more severe course in the second half of pregnancy or in the first months after delivery.High replication of the virus increases the frequency of gestational diabetes mellitus, hemostatic disorders, the threat of termination of pregnancy, gestosis, fetoplacental insufficiency, risk of bleeding in childbirth, premature birth, untimely discharge of amniotic fluid, and the birth of premature babies.Children become chronic carriers of HBsAd in neonatal hepatitis. These findings suggest that transplacental infection before birth may be a mechanism contributing to higher rates of failed prevention in newborns born to women with a high viral load.We could not find data on the features of the course and outcomes of viral hepatitis D in pregnant women in the available sources,. At the same time, it is known that mixed infection is more severe.Polymorphisms of genes associated with the regulation of the state of the vascular wall can have a significant impact on the course of infection.The high prevalence of hepatitis D infection in different parts of the world indicates the need for a comprehensive study of this disease, followed by the development of special programs for the prevention, early diagnosis and treatment of hepatitis B and D in pregnant women. Гепатит В наиболее распространен среди лиц молодого возраста, что объясняется путями заражения – парентеральным, половым и вертикальным. В районах, где вирусный гепатит В (HBV) является эндемичным заболеванием, передача инфекции от матери ребенку является основным путем заражения детей.Имеющиеся современные данные по течению и исходам хронического вирусного гепатита В у беременных противоречивы. Некоторые авторы утверждают, что обострение хронического гепатита В у беременных чаще происходит в первом и в третьем триместрах, а с увеличением срока гестации отмечается ухудшение функции печени и растёт риск развития фульминантной печеночной недостаточности. Другие исследователи наблюдали более тяжелое течение во второй половине беременности или в первые месяцы после родов.При выраженной репликации вируса повышается частота возникновения гестационного сахарного диабета, нарушений гемостаза, угрозы прерывания беременности, гестозов, фетоплацентарной недостаточности, и это приводит к повышению риска развития кровотечений в родах, преждевременных родов, несвоевременного отхождения околоплодных вод, рождения недоношенных детей.При неонатальном гепатите дети становятся хроническими носителями HВsAg. Эти данные свидетельствуют о том, что трансплацентарная инфекция до рождения может быть механизмом, способствующим более высоким показателям неудачной профилактики у новорожденных, родившихся у женщин с высокой вирусной нагрузкой.В доступных источниках мы не смогли найти данных об особенностях течения и исходов вирусного гепатита D у беременных. В то же время известно, что микстинфекция протекает тяжелее. Полиморфизм генов, связанных с регуляцией состояния сосудистой стенки, может оказывать существенное влияние на течение инфекции. Широкая распространенность инфекции гепатита D в разных частях мира указывает на необходимость всестороннего изучения этого заболевания с последующей разработкой специальных программ по профилактике, ранней диагностике и лечению гепатитов B и D у беременных женщин.

Back reaction, covariant anomaly and effective action

In the presence of back reaction, we first produce the one-loop corrections for the event horizon and Hawking temperature of the Reissner-Nordstr\"om black hole. Then, based on the covariant anomaly cancelation method and the effective action technique, the modified expressions for the fluxes of gauge current and energy momentum tensor, due to the effect of back reaction, are obtained. The results are consistent with the Hawking fluxes of a (1+1)-dimensional blackbody at the temperature with quantum corrections, thus confirming the robustness of the covariant anomaly cancelation method and the effective action technique for black holes with back reaction.Comment: 17 page

Anomaly analysis of Hawking radiation from Kaluza-Klein black hole with squashed horizon

Considering gravitational and gauge anomalies at the horizon, a new method that to derive Hawking radiations from black holes has been developed by Wilczek et al. In this paper, we apply this method to non-rotating and rotating Kaluza-Klein black holes with squashed horizon, respectively. For the rotating case, we found that, after the dimensional reduction, an effective U(1) gauge field is generated by an angular isometry. The results show that the gauge current and energy-momentum tensor fluxes are exactly equivalent to Hawking radiation from the event horizon.Comment: 15 pages, no figures, the improved version, accepted by Eur. Phys. J.