356 research outputs found

    Radial HI Profiles at the Periphery of Galactic Disks: The Role of Ionizing Background Radiation

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    Observations of neutral hydrogen in spiral galaxies reveal a sharp cutoff in the radial density profile at some distance from the center. Using 22 galaxies with known HI distributions as an example, we discuss the question of whether this effect can be associated exclusively with external ionizing radiation, as is commonly assumed. We show that before the surface density reaches σHI0.5M/pc2\sigma_{\textrm{HI}}\le 0.5 {\cal M}_\odot/{\textrm {pc}}^2(the same for galaxies of different types), it is hard to expect the gas to be fully ionized by background radiation. For two of 13 galaxies with a sharp drop in the HI profile, the "steepening" can actually be caused by ionization. At the same time, for the remaining galaxies, the observed cutoff in the radial HI profile is closer to the center than if it was a consequence of ionization by background radiation and, therefore, it should be caused by other factors.Comment: 15 pages, 6 figure

    Modeling the UO2 reduction process

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    Methods of molecular dynamics and DFT calculations have been used to study the reduction mechanisms of UO2 as the most representative part of spent nuclear fuel to metallic uranium. It is shown that the critical softening of the combined modulus of elasticity C11-C12 to zero is the reason for the destruction of the UO2 crystal as a result of the removal of oxygen from it. This destruction is accompanied by an order-disorder phase transition in the oxygen subsystem of the crystal under consideration. DFT calculations indicate a continuous decrease in the band gap as oxygen is removed from the UO2 crystal. When the system reaches the composition U2O3, the band gap disappears and the system becomes electrically conductive. The appearance of the dielectric-conductor transition explains the realization of the FFC Cambridge process during the recovery of spent nuclear fuel. The passage of Li+ and Cl– ions of the LiCl melt through cylindrical channels in a UO2 crystal with cross-sectional radii from 0.25 up to 2 nm has been studied. The strength of the external electric field required for the passage of these channels decreases with an increase in the channel cross section, and the number of Cl– ions entering the channel increases. On the walls of the channels that pass ions with charges of both signs, colonies of adsorbed Cl– and Li+ atoms appear separated from each other, between which strong electric fields are formed. The existence of such fields can cause Li+ ions to move deep into the material being reduced.https://doi.org/10.15826/elmattech.2023.2.01

    Ethnodemography of Bashkirs in Regions of Russia (1970—2010)

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    The issues of ethno-demographic and ethno-linguistic development of the Bashkir population in the regions of the Russian Federation are considered. It is noted that the tendencies of demographic processes among the Bashkirs in the regions and in the republic of the same name are very different. The features of the ethnodemographic development of the Bashkirs in the regions of their historical settlement are shown, in which general trends coincide with the demographic processes in the country as a whole. It cannot be said about the Republic of Bashkortostan, which is characterized by sharp fluctuations in the size of the titular ethnic group. The dynamics of the ethnic and linguistic identity of the Bashkir population in the regions of historical settlement is revealed in a comparative aspect with the subjects to which the Bashkirs moved at a later time and in which their number is a small proportion. The novelty of the study lies in the fact that it was the first to analyze the ethno-demographic and ethno-linguistic aspects of the development of the Bashkirs in the Russian Federation, including in the regions of their historical settlement. The relevance of the study is due to the fact that the issue of the demographic development of the Bashkir population at the present stage, especially in the republic of the same name, has acquired an ethnopolitical discourse. It has been proven that, despite the policy of reviving ethnicity and the native language, the Bashkirs, like other peoples, are gradually losing it in favor of being recognized as a native Russian

    Predicted facies, sedimentary structures and potential resources of Jurassic petroleum complex in S-E Western Siberia (based on well logging data)

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    This paper is devoted to the current problem in petroleum geology and geophysics- prediction of facies sediments for further evaluation of productive layers. Applying the acoustic method and the characterizing sedimentary structure for each coastal-marine-delta type was determined. The summary of sedimentary structure characteristics and reservoir properties (porosity and permeability) of typical facies were described. Logging models SP, EL and GR (configuration, curve range) in interpreting geophysical data for each litho-facies were identified. According to geophysical characteristics these sediments can be classified as coastal-marine-delta. Prediction models for potential Jurassic oil-gas bearing complexes (horizon J[1]{1}) in one S-E Western Siberian deposit were conducted. Comparing forecasting to actual testing data of layer J[1]{1} showed that the prediction is about 85%

    Crop wild relatives in the protected areas of the Republic of Bashkortostan

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    Background. Comprehensive research into crop wild relatives (CWR) is essential to ensure food security. Protected areas serve as the main reserves for CWR in situ conservation and their population genetics studies. There are four federal protected areas in the Republic of Bashkortostan: the Bashkiria National Park, the Shulgan-Tash State Biosphere Nature Reserve, the South Ural and Bashkir State Nature Reserves.Materials and methods. The floristic study of CWR was conducted using the standard route method. The methods of comparative floristics were applied in the CWR analysis,. The economic value of plant species was assessed according to the ranking developed at the N.I. Vavilov All-Russian Institute of Plant Genetic Resources.Results. In total, out of 259 species of CWR growing in Bashkortostan, 186 (72%) occur in the federal protected areas, with the highest number in the Bashkiria National Park (148 spp.). Species belonging to the Poaceae, Fabaceae, Rosaceae and Lamiaceae families and the Poa L., Trifolium L., Lathyrus L., Allium L. genera are predominant. CWR are mainly confined to the forest meadow, forest margin, steppe and riverside communities. Alpine and raised bog CWR species occur only in the South-Ural Nature Reserve. There are 13 regional endemics in the studied territories and 34 species on their range boundaries. Of the 23 CWR species listed in the regional Red Book, seven are conserved in the surveyed areas: Allium obliquum L., Crambe tataria Sebeok, Linum uralense Juz., Melilotoides platycarpos (L.) Soják, Oxycoccus microcarpus Turcz. ex Rupr., Rubus arcticus L., and R. humulifolius C.A. Mey.Conclusion. Monitoring of the rare CWR species populations is required in the surveyed protected areas. Eight CWR species are recommended for further population genetics studies: Amygdalus nana L., Cerasus fruticosa Pall., Allium rubens Schrad. ex Willd., A. obliquum L., A. schoenoprasum L., Lathyrus gmelinii Fritsch, L. litvinovii Iljin, and L. sylvestris L

    (Anti-)self-dual homogeneous vacuum gluon field as an origin of confinement and SUL(NF)×SUR(NF)SU_L(N_F)\times SU_R(N_F) symmetry breaking in QCD

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    It is shown that an (anti-)self-dual homogeneous vacuum gluon field appears in a natural way within the problem of calculation of the QCD partition function in the form of Euclidean functional integral with periodic boundary conditions. There is no violation of cluster property within this formulation, nor are parity, color and rotational symmetries broken explicitly. The massless limit of the product of the quark masses and condensates, mfψˉfψfm_f \langle \bar\psi_f \psi_f \rangle, is calculated to all loop orders. This quantity does not vanish and is proportional to the gluon condensate appearing due to the nonzero strength of the vacuum gluon field. We conclude that the gluon condensate can be considered as an order parameter both for confinement and chiral symmetry breaking.Comment: 16 pages, LaTe

    Mineral-petrochemical wallrock alteration of rocks in Bericul gold-ore deposit (Kuznetsk Alatau)

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    The distribution of mineral associations in near-veined zonal propylite-beresite metasomatic columns of mesothermal Bericul gold-ore deposit was analyzed. However, the polymineral composition in the inner (axial and adjacent with it rear) zones is inconsistent to the existing metasomatic column theoretical model. According to Korzhinskii metasomatic zoning theory, implied monomineral (quartz) and binary-mineral (quartz, sericite) compositions are characteristic of axial and rear zones, respectively. In common with above-mentioned facts, the zoning formation of differential component mobility is influenced by two additional factors: counter diffusion of components from fractured fluids into pores and diffusion mechanism of mass transfer it's from pores fluids into fractured of rock-fluid systems

    Atomic and Molecular Gas Components in Spiral Galaxies of the Virgo Cluster

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    Based on two models, we investigate the molecular-to-atomic gas ratio in Virgo cluster galaxies in comparison with field galaxies. We show that the enhanced metallicity for cluster members and the ram pressure stripping of atomic gas from the disk periphery cannot fully explain the observed gas component ratios. The additional environmental factors affecting the interstellar medium and leading to an increase in the molecular gas fraction should be taken into account for cluster galaxies.Comment: 11 pages, 4 figure

    МУЛЬТИСПИРАЛЬНАЯ КОМПЬЮТЕРНАЯ ТОМОГРАФИЯ В ОБСЛЕДОВАНИИ ДОНОРОВ ПРИ ТРАНСПЛАНТАЦИИ ФРАГМЕНТА ПЕЧЕНИ ОТ ЖИВОГО РОДСТВЕННОГО ДОНОРА

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    The purpose was to determine the possibilities of Multispiral computed tomography (MSCT) in evaluation of potential living liver related donors. A total of 104 potential donors were examined with «Siemens» Somatom «Sensation-64» MSCT-scanner. The technique provides comprehensive preharvest analyses of vascular anatomy and liver volumes in living family related liver donors. Цель работы – показать возможности мультиспиральной компьютерной томографии в обследовании до- норов при родственной трансплантации печени. Было обследовано 104 потенциальных донора фрагмента печени. Применялся томограф Somatom «Sensation-64» фирмы Siemens, протокол мультифазного скани- рования. Метод показал высокие диагностические возможности в расчетах объемов фрагмента печени, артериального и венозного кровоснабжения печени.
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