Black hole spins in coalescing binary black holes

The possible formation mechanisms of massive close binary black holes (BHs) that can merge in the Hubble time to produce powerful gravitational wave bursts detected during advanced LIGO O1 and O2 science runs include the evolution from field low-metallicity massive binaries, the dynamical formation in dense stellar clusters and primordial BHs. Different formation channels produce different source distributions of total masses ${M_\mathrm{tot}}$ and effective spins $\chi_\mathrm{eff}$ of coalescing binary BHs. Using a modified \textsc{bse} code, we carry out extensive population synthesis calculations of the expected effective spin and total mass distributions from the standard field massive binary formation channel for different metallicities of BH progenitors (from zero-metal Population III stars up to solar metal abundance), different initial rotations of the binary components, stellar wind mass loss prescription, different BH formation models and a range of common envelope efficiencies. The stellar rotation is treated in two-zone (core-envelope) approximation using the effective core-envelope coupling time and with an account of the tidal synchronization of stellar envelope rotation during the binary system evolution. The results of our simulations, convolved with the metallicity-dependent star-formation history, show that the total masses and effective spins of the merging binary black holes detected during LIGO O1-O2 runs but the heaviest one (GW170729) can be simultaneously reproduced by the adopted BH formation models. Noticeable effective spin of GW170729 requires additional fallback from the rotating stellar envelope.Comment: 18 pages, 11 figures, accepted to MNRAS after taking into account star-formation rate history for comparison of the calculated BH-BH coalescences with observed systems, LIGO/Virgo GWTC-1 sources adde

К ВОПРОСУ О ПОСТРОЕНИИ ИНДИКАТОРОВ СТЕПЕНИ ИНТЕГРАЦИИ СТРАН ЕАЭС

In this article the authors explain the need to improve monitoring instruments for the integration processes within the EAEU. They also argue that in order to better the information support of managerial decisions it is very important to develop methodological principles and methodical provision for evaluating economic effects of integration processes in the EAEU member-states. In this regard the authors review three aspects of cooperation among the EAEU countries (foreign trade, exchange of services and exchange of capital) and assesses the adequacy of the indicators that are used today to reflect the degree of integration of a single EAEU member-country with a group of EAEU partners on a quantitative example of Russia’s external economic relations in 2013-2015.It is necessary to expand the system of indicators aimed mostly at multi-aspect reflection of inter-country exchange of services at the expanse of the following indicators: the amount of accumulated capital in the countries’ economies as a result of mutual direct investment; the assessment of the relative degree of integration - using the reference method; the magnitude of real shifts in the degree of integration- using the physical volume indices of indicators. The authors propose approaches to its formation and justify the demand in additional information and statistical support. Methodological proposals for the new indicators are illustrated with experimental calculations for Russia.The choice of the GDP as the denominator in the formula for calculating the integration index (by any of the three integration directions) is proved to be valid. The article presents several suggestions on other possible approaches to generating the denominator for the formula with which the strength of integration relationships is estimated. There are examples illustrating differences in assessments depending on the methodological approach - the choice of a particular indicator of economic performance (used in assessing the degree of integration) and insights regarding if there has been a positive shift in the degree of integration or there was none. The authors emphasize the debatable nature of the question of preferring one approach to another in estimating the degree of integration of the EAEU member-states.В статье аргументируются необходимость совершенствования инструментария мониторинга интеграционных процессов в рамках ЕАЭС, актуальность развития методологических принципов и методического обеспечения оценок экономических эффектов интеграционных процессов в целях улучшения информационного обеспечения управленческих решений. Авторами рассматриваются три аспекта взаимодействия стран ЕАЭС: внешняя торговля, обмен услугами и обмен капиталом и оценивается достаточность состава индикаторов, применяемых сегодня для отражения степени интеграции отдельно взятой страны ЕАЭС с группой партнеров по ЕАЭС на количественном примере внешнеэкономических связей России в 2013-2015 гг.Рассматривается версия расширенной системы показателей, предназначенной главным образом для многоаспектного отражения межстранового обмена услугами, за счет таких индикаторов, как размер накопленного капитала в экономиках стран в результате операций взаимного прямого инвестирования, оценка относительной степени интеграции (с применением эталонного метода) и величина реальных сдвигов в степени интеграции (с использованием индексов физического объема показателей). Предлагаются подходы к их построению и обосновываются потребности в дополнительном информационно-статистическом обеспечении. Методологические предложения по новым индикаторам иллюстрируются экспериментальными расчетами по России.Авторами подтверждается обоснованность выбора показателя ВВП в знаменателе формулы, по которой рассчитывается показателеь интеграции (по любому из трех рассматриваемых направлений интеграции). Высказывается ряд соображений по другим возможным подходам к формированию знаменателя формулы, в соответствии с которой рассчитывается теснота интеграционных связей. Приводятся примеры, иллюстрирующие различия в оценках в зависимости от методологического подхода - выбора того или иного обобщающего показателя экономической результативности (используемого в оценке степени интеграции), делаются содержательные выводы - есть положительный сдвиг в степени интеграции или его нет. Подчеркивается дискуссионность вопроса о предпочтительности того или иного подхода в расчетах степени интеграции стран ЕАЭС

Novel focused OCT-LIF endoscope

Combined optical coherence tomography (OCT) and laser-induced fluorescence (LIF) endoscopy has shown higher sensitivity and specificity for distinguishing normal tissue from adenoma when compared to either modality alone. Endoscope optical design is complicated by the large wavelength difference between the two systems. A new high-resolution endoscope 2 mm in diameter is presented that can create focused beams from the ultraviolet to near-infrared. A reflective design ball lens operates achromatically over a large wavelength range, and employs TIR at two faces and reflection at a third internal mirrored face. The 1:1 imaging system obtains theoretically diffraction-limited spots for both the OCT (1300 nm) and LIF (325 nm) channels

The Evolution of Compact Binary Star Systems

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

The effect of climate change on avian offspring production: A global meta-analysis

Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations. A total of 56.7% of populations showed a declining trend in offspring production (significant in 17.4%), whereas 43.3% exhibited an increase (significant in 10.4%). The results show that climatic changes affect offspring production through compounded effects on ecological and life history traits of species. Migratory and larger-bodied species experienced reduced offspring production with increasing temperatures during the chick-rearing period, whereas smaller-bodied, sedentary species tended to produce more offspring. Likewise, multi-brooded species showed increased breeding success with increasing temperatures, whereas rising temperatures were unrelated to repro- ductive success in single-brooded species. Our study suggests that rapid declines in size of bird populations reported by many studies from different parts of the world are driven only to a small degree by changes in the production of young