69 research outputs found
The Commonwealth of the Independent States as an Organization of Missed Opportunities: the Russian Leadership's Errors in the 1990s
Following the collapse of the USSR, the post-Soviet states applied their foreign policy and solved economic and military problems in cooperation with one another. They established the Commonwealth of the Independent States and the other integration associations, both within and beyond the CIS. This article deals with the problems of integration of the post-Soviet states. It discovers the main reasons why the CIS failed to grow in a very integration union. The authors believe that the main cause was a short-foresighted policy of the Russian leadership under the presidency of Boris Yeltsi
The Commonwealth of Independent States as a Way to a «Civilized Divorce»
The article describes the events, which took place in the USSR in its last years. It discovers the reasons for the collapse of the Soviet Union and the establishment of the Commonwealth of Independent States. It explains why the CIS did not grow in a new Union state and did become nothing more than a mechanism for a “civilized divorce” of the former Soviet republics
Several New Active Galactic Nuclei Among X-ray Sources Detected by INTEGRAL and SWIFT Observatories
We present the results of the optical identifications of a set of X-ray
sources from the all-sky surveys of INTEGRAL and SWIFT observatories. Optical
data were obtained with Russian-Turkish 1.5-m Telescope (RTT150). Nine X-ray
sources were identified as active galactic nuclei (AGNs). Two of them are
hosted by nearby, nearly exactly edge-on, spiral galaxies MCG -01-05-047 and
NGC 973. One source, IGR J16562-3301, is most probably BL Lac object (blazar).
Other AGNs are observed as stellar-like nuclei of spiral galaxies, with broad
emission lines in their spectra.
For the majority of our hard X-ray selected AGNs, their hard X-ray
luminosities are well-correlated with the luminosities in [OIII],5007 optical
emission line. However, the luminosities of some AGNs deviate from this
correlation. The fraction of these objects can be as high as 20%. In
particular, the flux in [OIII] line turns to be lower in two nearby edge-on
spiral galaxies, which can be explained by the extinction in their galactic
disks.Comment: 9 pages, 3 figures, accepted for publication in Astronomy Letters,
the original text in Russian can be found at
http://hea.iki.rssi.ru/~rodion/poptid.pd
The 400 square degrees ROSAT PSPC galaxy cluster survey: Catalog and statistical calibration
We present a catalog of galaxy clusters detected in a new ROSAT PSPC survey.
The survey is optimized to sample, at high redshifts, the mass range
corresponding to T> keV clusters at z=0. Technically, our survey is the
extension of the 160 square degrees survey (Vikhlinin etal 98a, Mullis etal
2003). We use the same detection algorithm, thus preserving high quality of the
resulting sample; the main difference is a significant increase in sky
coverage. The new survey covers 397 square degrees and is based on 1610 high
Galactic latitude ROSAT PSPC pointings, virtually all pointed ROSAT data
suitable for the detection of distant clusters. The search volume for X-ray
luminous clusters within z<1 exceeds that of the entire local Universe (z<0.1).
We detected 287 extended X-ray sources with fluxes f>1.4e-13 erg/s/cm^2 in the
0.5-2 keV energy band, of which 266 (93%) are optically confirmed as galaxy
clusters, groups or individual elliptical galaxies. This paper provides a
description of the input data, the statistical calibration of the survey via
Monte-Carlo simulations, and the catalog of detected clusters. We also compare
the basic results to those from previous, smaller area surveys and find good
agreement for the log N - log S distribution and the local X-ray luminosity
function. Our sample clearly shows a decrease in the number density for the
most luminous clusters at z>0.3. The comparison of our ROSAT-derived fluxes
with the accurate Chandra measurements for a subset of high-redshift clusters
demonstrates the validity of the 400 square degree survey's statistical
calibration.Comment: Submitted to ApJS. 21 pages using emulateapj. More information ans
survey data tables are available at http://hea-www.harvard.edu/400d and
http://hea.iki.rssi.ru/400
Vertical Structure of the Outer Accretion Disk in Persistent Low-Mass X-Ray Binaries
We have investigated the influence of X-ray irradiation on the vertical
structure of the outer accretion disk in low-mass X-ray binaries by performing
a self-consistent calculation of the vertical structure and X-ray radiation
transfer in the disk. Penetrating deep into the disk, the field of scattered
X-ray photons with energy \,keV exerts a significant influence on
the vertical structure of the accretion disk at a distance
\,cm from the neutron star. At a distance \,cm,
where the total surface density in the disk reaches
\,g\,cm, X-ray heating affects all layers of an
optically thick disk. The X-ray heating effect is enhanced significantly in the
presence of an extended atmospheric layer with a temperature
\,K above the accretion disk. We have derived
simple analytic formulas for the disk heating by scattered X-ray photons using
an approximate solution of the transfer equation by the Sobolev method. This
approximation has a \,% accuracy in the range of X-ray photon
energies \,keV.Comment: 19 pages, 8 figures, published in Astronomy Letter
Sensitivity and Insensitivity of Galaxy Cluster Surveys to New Physics
We study the implications and limitations of galaxy cluster surveys for
constraining models of particle physics and gravity beyond the Standard Model.
Flux limited cluster counts probe the history of large scale structure
formation in the universe, and as such provide useful constraints on
cosmological parameters. As a result of uncertainties in some aspects of
cluster dynamics, cluster surveys are currently more useful for analyzing
physics that would affect the formation of structure than physics that would
modify the appearance of clusters. As an example we consider the Lambda-CDM
cosmology and dimming mechanisms, such as photon-axion mixing.Comment: 24 pages, 8 eps figures. References added, discussion of scatter in
relations between cluster observables lengthene
Концентрация мочевой кислоты и показатели липопероксидации клеточных мембран при дыхательной гипоксии у детей с острыми бронхолегочными заболеваниями
A comparative analysis of uric acid level in children with acute bronchopulmonary diseases (80 pneumonic and 65 bronchitis patients) revealed a clear correlation between its concentration and a respiratory failure severity, and a hypoxaemia level as well. This fact confirms a role of hypoxia in purine nucleotides catabolism, resulting in uric acid production. The relation established between a uric acid concentration and lipid peroxidation products content proved the role of purine metabolism acute disorders in a lipid peroxidation enhancement caused by a xanthinoxidase activation that had been shown experimentally. An application of metronidazole as a xanthinoxidase inhibitor in severe pneumonia and Riboxine as a source of inosine in obstructive bronchitis with severe respiratory disorders led to shortening of a dyspnoe period and of length of stay in an intensive care unit and also facilitated an inhibition of excessive lipid peroxidation of cell membranes.Сравнительный анализ уровня мочевой кислоты у детей с острыми бронхолегочными заболеваниями (80 с пневмонией и 65 с бронхитом) показал четкую зависимость ее концентрации от степени дыхательной недостаточности и уровня гипоксемии, что явилось подтверждением роли гипоксии в катаболизме пуриновых нуклеотидов, конечным продуктом которого и является мочевая кислота. Установленная связь между концентрацией мочевой кислоты и содержанием продуктов липопероксидации подтвердила доказанную в эксперименте роль нарушения пуринового обмена в усилении опосредованного активацией ксантиноксидазы, перекисного окисления липидов. Применение метронидазола, как ингибитора ксантиноксидазы при тяжелых формах пневмонии и рибоксина, как источника инозина, при обструктивных формах бронхита с тяжелыми дыхательными расстройствами сокращало период одышки, время нахождения пациентов в отделении реанимации и способствовало торможению чрезмерной липопероксидации клеточных мембран
КОМПЬЮТЕРНАЯ ТОМОГРАФИЯ С ИСПОЛЬЗОВАНИЕМ МОДЕЛЬ-БАЗИРОВАННЫХ ИТЕРАТИВНЫХ РЕКОНСТРУКЦИЙ В КЛИНИЧЕСКОЙ ПРАКТИКЕ
Due to the widespread introduction of CT in clinical practice, the issue of reducing the radiation dose remains one of the most urgent. One of the ways to reduce radiation exposure is to improve the reconstruction algorithms of CT images. When using model interactive reconstruction, images are repeatedly processed to maximize the elimination of digital noise, which allows lowdose studies to be performed without compromising visual quality. The literature review presents the possibilities of applying model iterative reconstruction in CT studies of various organs and systems, including low-dose studies with a radiation exposure of less than 1 mSv, assessment the quality of studies and visualization of the pathology of various organs and systems. The most popular new technique is for screening studies, for example, for LDCT screening of lung cancer, and studies that require high resolution, for example, for CT-coronarography.В связи с широким внедрением КТ в клиническую практику вопрос о снижении дозы облучения остается одним из самых насущных. Одним из направлений снижения лучевой нагрузки является совершенствование алгоритмов реконструкции КТ-изображений. При использовании модельной интерактивной реконструкции изображения многократно обрабатываются для максимального устранения цифрового шума, что позволяет выполнять низкодозовые исследования без снижения качества визуализации. В обзоре литературы представлены возможности применения модельной итеративной реконструкции при КТ-исследовании различных органов и систем, в том числе при низкодозовых исследованиях с дозой облучения менее 1 мЗв, оценка качества выполненных исследований и визуализации патологии различных органов и систем. Наиболее востребованной новая методика является для скрининговых исследований, например, для НДКТ-скрининга рака легкого, и исследований, в которых требуется высокое разрешение, например, для КТ- коронарографии
Design, Performance, and Calibration of CMS Hadron-Barrel Calorimeter Wedges
Extensive measurements have been made with pions, electrons and muons on four production wedges of the Compact Muon Solenoid (CMS) hadron barrel (HB) calorimeter in the H2 beam line at CERN with particle momenta varying from 20 to 300 GeV/c. Data were taken both with and without a prototype electromagnetic lead tungstate crystal calorimeter (EB) in front of the hadron calorimeter. The time structure of the events was measured with the full chain of preproduction front-end electronics running at 34 MHz. Moving-wire radioactive source data were also collected for all scintillator layers in the HB. These measurements set the absolute calibration of the HB prior to first pp collisions to approximately 4%
A unifying view of Gamma Ray Burst Afterglows
We selected a sample of 33 Gamma Ray Bursts (GRBs) detected by Swift, with
known redshift and optical extinction at the host frame. For these, we
constructed the de-absorbed and K-corrected X-ray and optical rest frame light
curves. These are modelled as the sum of two components: emission from the
forward shock due to the interaction of a fireball with the circum-burst medium
and an additional component, treated in a completely phenomenological way. The
latter can be identified, among other possibilities, as "late prompt" emission
produced by a long lived central engine with mechanisms similar to those
responsible for the production of the "standard" early prompt radiation. Apart
from flares or re-brightenings, that we do not model, we find a good agreement
with the data, despite of their complexity and diversity. Although based in
part on a phenomenological model with a relatively large number of free
parameters, we believe that our findings are a first step towards the
construction of a more physical scenario. Our approach allows us to interpret
the behaviour of the optical and X-ray afterglows in a coherent way, by a
relatively simple scenario. Within this context it is possible to explain why
sometimes no jet break is observed; why, even if a jet break is observed, it is
often chromatic; why the steepening after the jet break time is often shallower
than predicted. Finally, the decay slope of the late prompt emission after the
shallow phase is found to be remarkably similar to the time profile expected by
the accretion rate of fall-back material (i.e. proportional to t^{-5/3}),
suggesting that this can be the reason why the central engine can be active for
a long time.Comment: 20 pages, 17 figures, Accepted for publication in MNRA
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