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Marin Bachvarov 《GeoJournal》1997,43(3):215-224
Although a constant trickle of outmigrants and several larger waves (mostly to Turkey) are characteristic for the modern history of Bulgaria, its ethnic composition was relatively stable. The ethnic Bulgarians are a clear majority, the largest minority groups being in descending order the Turks, Roma (Gypsies), the Muslim Bulgarians and several much smaller groups. The geographical patterns of distribution have been analysed. Over time, the policies of the Bulgarian state towards the minority groups have been varying between benevolence and restriction measures. The ethnocultural communities have worked out moduses of co-existence preventing the escalation of conflicts at the local level.  相似文献   
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The paper presents a study of the effect of excessive amounts of organic matter (OM) on Arctic benthos. The source of nontoxic OM is from the mariculture of blue mussels in the White Sea (north-western area of Russia). The use of multivariate analysis procedures made it evident that in the Arctic conditions benthos is incapable of annual utilization of more than 1.5 kg dry OM m−2 from an external source. Mineralization of OM accumulated in sediments will deteriorate the oxygen regime. The critical concentration of OM in sediments is 9–10%. An excess over this threshold leads to the formation of oxygen-free zones at the bottom, and degradation of benthos community.  相似文献   
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This paper is devoted to the detection and identification of icebergs in the Russian Arctic Seas from the use of high- and medium-resolution radar and optical images from EROS-B, Radarsat-1, Radarsat-2, SPOT-4 and SPOT-5 Earth observation satellites. In July–September of 2011–2013, the SCANEX Research and Development Center, the Federal State Unitary Enterprise Atomflot, and other partner organizations provided operational satellite monitoring of icebergs in the Kara Sea and the Laptev Sea. More than 130 highly detailed optical and radar images were received and processed. The Vilkitsky Strait—one of the narrowest and most dangerous places within the Northern Sea Route—was chosen as an experimental polygon. As a result, iceberg location in the strait during the 2011–2013 navigation periods was analyzed, as were the iceberg size, area, drift direction, and height.  相似文献   
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The possibilities of a multiangle method of radar diagnostics to determine thickness of an oil film on a sea surface by comparing the radar data with the quantitative modeling results obtained using the model of oil spreading dynamics are analyzed. The experimental results of the remote sensing of the Caspian Sea water area near the Neftyanye Kamni oil field by the Envisat-1 synthetic aperture radar (SAR) and the new Floating Objects Tracking System (FOTS) model of oil spreading are used for the analysis. The model allows to calculate the dynamics and change in the mass and size of an oil slick basing only on the available data of satellite measurements and atmospheric reanalysis.The model takes into account the main processes that influence the slick formation (gravity spreading, advective transport, dispersion, emulsification, turbulent mixing, and evaporation). This model is used to calculate the thickness evolution and dynamics of the displacement of oil slicks in the period between two consecutive radar images of this region (0.5–4 days) and to estimate the volumes of oil spilled in the field. The good consistence of the height of the oil film calculated using radar measurements and the modeling results confirms the method’s reliability.  相似文献   
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New data on the mineral composition of the Ozernoye meteorite, found in the Kurgan region in 1983, are presented. It has been found that that the meteorite’s matter is composed of olivine (chrysolite), orthopyroxene (bronzite), clinopyroxene (augite), maskelynite, chromite, ilmenite, metals Fe and Ni (kamasite, taenite), sulfides (troilite, pentlandite), chlorapatite, and merrillite. Augite, taenite, pentlandite, and merrillite were identified in the Ozernoye meteorite for the first time. The chemical compositions are given for all these minerals. The meteorite itself is an ordinary chondrite stone belonging to petrological type L5.  相似文献   
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The article presents a review of scientific problems and methods of ultraviolet astronomy, focusing on perspective scientific problems (directions) whose solution requires UV space observatories. These include reionization and the history of star formation in the Universe, searches for dark baryonic matter, physical and chemical processes in the interstellar medium and protoplanetary disks, the physics of accretion and outflows in astrophysical objects, from Active Galactic Nuclei to close binary stars, stellar activity (for both low-mass and high-mass stars), and processes occurring in the atmospheres of both planets in the solar system and exoplanets. Technological progress in UV astronomy achieved in recent years is also considered. The well advanced, international, Russian-led Spektr-UV (World Space Observatory—Ultraviolet) project is described in more detail. This project is directed at creating a major space observatory operational in the ultraviolet (115–310 nm). This observatory will provide an effective, and possibly the only, powerful means of observing in this spectral range over the next ten years, and will be an powerful tool for resolving many topical scientific problems.  相似文献   
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