Неоднородное строение магнитоактивного слоя Курильской островной дуги

An innovative technology of anomalous magnetic field inversion was applied to construct 2D models of the magnetic layer using three profiles crossing the southern, central and northern parts of the Kuril Island Arc. In the frontal area of the northern and southern parts, a zone of increased effective magnetization is clearly distinguished. In the central part of the island arc, increased magnetization is much less pronounced. Anomalous zones of positive effective magnetization have a deep part, the so-called "serpentinite wedge". The inhomogeneous lateral structure of the magnetic layer of the Kuril Island Arc suggests differences in the fluid regime and is reflected in the distribution of modern seismicity. На основе оригинальной технологии инверсии аномального магнитного поля построены двумерные модели магнитоактивного слоя по трем профилям, пересекающим Курильскую островную дугу в южной, центральной и северной части. В северной и южной части островной дуги во фронтальной зоне уверенно выделяется зона повышенной эффективной намагниченности. В центральной части дуги зона повышенной намагниченности выражена существенно слабее. Аномальные зоны положительной эффективной намагниченности имеют глубинную часть, которая соответствует так называемому «серпентинитовому валу». Выявленное неоднородное латеральное строение магнитоактивного слоя Курильской островной дуги свидетельствует о различиях во флюидном режиме и находит свое отражение в распределении современной сейсмичности

Observations of giant outbursts from Cygnus X-1

We present interplanetary network localization, spectral, and time history information for 7 episodes of exceptionally intense gamma-ray emission from Cygnus X-1. The outbursts occurred between 1995 and 2003, with durations up to \~28000 seconds. The observed 15 - 300 keV peak fluxes and fluences reached 3E-7 erg /cm2 s, and 8E-4 erg / cm2 respectively. By combining the triangulations of these outbursts we derive an ~1700 square arcminute (3 sigma) error ellipse which contains Cygnus X-1 and no other known high energy sources. The outbursts reported here occurred both when Cyg X-1 was in the hard state as well as in the soft one, and at various orbital phases. The spectral data indicate that these outbursts display the same parameters as those of the underlying hard and soft states, suggesting that they represent another manifestation of these states.Comment: 27 pages, 9 figures. Revised version. Accepted for publication in the Astrophysical Journal, tentatively scheduled for October 20, 2003 Part

Multi-Wavelength Studies of the Optically Dark Gamma-Ray Burst 001025A

We identify the fading X-ray afterglow of GRB 001025A from XMM-Newton observations obtained 1.9-2.3 days, 2 years, and 2.5 years after the burst. The non-detection of an optical counterpart to an upper limit of R=25.5, 1.20 days after the burst, makes GRB 001025A a ``dark'' burst. Based on the X-ray afterglow spectral properties of GRB 001025A, we argue that some bursts appear optically dark because their afterglow is faint and their cooling frequency is close to the X-ray band. This interpretation is applicable to several of the few other dark bursts where the X-ray spectral index has been measured. The X-ray afterglow flux of GRB 001025A is an order of magnitude lower than for typical long-duration gamma-ray bursts. The spectrum of the X-ray afterglow can be fitted with an absorbed synchrotron emission model, an absorbed thermal plasma model, or a combination thereof. For the latter, an extrapolation to optical wavelengths can be reconciled with the R-band upper limit on the afterglow, without invoking any optical circumburst absorption, provided the cooling frequency is close to the X-ray band. Alternatively, if the X-ray afterglow is due to synchrotron emission only, seven magnitudes of extinction in the observed R-band is required to meet the R-band upper limit, making GRB 001025A much more obscured than bursts with detected optical afterglows. Based on the column density of X-ray absorbing circumburst matter, an SMC gas-to-dust ratio is insufficient to produce this amount of extinction. The X-ray tail of the prompt emission enters a steep temporal decay excluding that the tail of the prompt emission is the onset of the afterglow (abridged).Comment: 32 pages, 8 figures, ApJ in pres

Prevalence of Risk Factors of Thromboembolic Complications in Women after Major Joint Arthroplasty in the Republic of Sakha (Yakutia)

The aim of this study was to assess the risk factors for thromboembolic complications after total arthroplasty of large joints in women in Yakutia conditions to optimize the management tactics of this category of patients. The average age of women was 59.98±11.56 years in the age range from 50 to 70 years. In order to validate the study, women were divided into 2 groups. The main group consisted of 284 women undergoing total knee arthroplasty (Group 1). The comparison group included 147 women undergoing total hip arthoplasty (Group 2). The study demonstrated that hypertension was more common in patients of Group 1 than in patients of Group 2. However, the incidence of coronary heart disease and heart rhythm disorder was detected most frequently in patients with total hip arthroplasty. Obesity, thrombosis of the veins of the lower extremities, and liver disease were detected with almost the same frequency in women with total knee arthroplasty and those with total hip arthroplasty. The frequency of occurrence of complications depending on the risk factors for thromboembolic complications and the type of surgical treatment of the joint was equal in the two groups of studied patients

On the Possibility of Identification of a Short/Hard Burst GRB 051103 with the Giant Flare from a Soft Gamma Repeater in the M81 Group of Galaxies

The light curve, energy characteristics, and localization of a short/hard GRB 051103 burst are considered. Evidence in favor of identifying this event with a giant flare from a soft gamma repeater in the nearby M81 group of interacting galaxies is discussed.Comment: 11 pages, 4 figures, accepted for publication in Astronomy Letters, correction of a typo on page

Inhomogeneous structure of magnetic layer of the Kuril Island Arc

An innovative technology of anomalous magnetic field inversion was applied to construct 2D models of the magnetic layer using three profiles crossing the southern, central and northern parts of the Kuril Island Arc. In the frontal area of the northern and southern parts, a zone of increased effective magnetization is clearly distinguished. In the central part of the island arc, increased magnetization is much less pronounced. Anomalous zones of positive effective magnetization have a deep part, the so-called "serpentinite wedge". The inhomogeneous lateral structure of the magnetic layer of the Kuril Island Arc suggests differences in the fluid regime and is reflected in the distribution of modern seismicity

Temperature and salt content regimes in three shallow ice-covered lakes 1. Temperature, salt content, and density structure

A field study on the temperature, salt content, and density regime in three shallow ice-covered Karelian lakes is presented. The measurements show that the heat content increases during the whole ice-covered period. At ice formation a weak stable stratification existed in the lakes, with average temperatures about 1 degrees C. Thereafter, the stability of the stratification gradually increased, mainly due to pronounced temperature increases in the bottom layers. In mid-winter the bottom layer in the deep parts of the lakes obtained temperatures above 4 degrees C. The density stratification in these layers was stable, however, due to higher salt contents (increasing continuously during the winter) in the vicinity of the bottom. The horizontal variations in temperature and salt content were very small, and both parameters can be considered to be horizontally homogeneous. Under-ice convection was developed in two of the three investigated lakes during the second half of April, when heating due to penetrating solar radiation became apparent. Although no under-ice convection in the conventional sense occurred in the third lake (Uros), interior convection developed when the temperature exceeded 4 degrees C (the temperature of maximum density) there. The absence of under-ice convection in Lake Uros is most likely due to the higher vertical temperature gradient in the lake before spring heating and smaller extinction coefficient than in the other two lakes