3,625 research outputs found

    Cyclotomic shuffles

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    Analogues of 1-shuffle elements for complex reflection groups of type G(m,1,n)G(m,1,n) are introduced. A geometric interpretation for G(m,1,n)G(m,1,n) in terms of rotational permutations of polygonal cards is given. We compute the eigenvalues, and their multiplicities, of the 1-shuffle element in the algebra of the group G(m,1,n)G(m,1,n). Considering shuffling as a random walk on the group G(m,1,n)G(m,1,n), we estimate the rate of convergence to randomness of the corresponding Markov chain. We report on the spectrum of the 1-shuffle analogue in the cyclotomic Hecke algebra H(m,1,n)H(m,1,n) for m=2m=2 and small nn

    Formation of speech culture primary school teachers in today's language situation

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    The article considers the problems associated with the formation and perfection of speech culture of future primary school teachers. In this paper identifies the main features characteristic of the modern linguistic situation, the working methods aimed at the formation of linguistic and communicative competence of future teachers of primary school. Modeling speech situations is one of their effective exercise in the development of communication skills and mastery of the rules of modern literary languag

    Study of olivines from Omolon and Seymchan meteorites using X-ray diffraction and Mössbauer spectroscopy with a high velocity resolution

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    Study of olivine from Omolon and Seymchan meteorites was performed using X-ray diffraction and Mössbauer spectroscopy with a high velocity resolution. X-ray diffraction patterns were measured at room temperature while Mössbauer spectra were measured at 295 and 90 K. The orthorhombic crystal lattice parameters were evaluated for olivine from Omolon and Seymchan. These parameters appeared to be different for olivines from both meteorites. Mössbauer spectral components related to 57Fe in crystallographically non-equivalent sites M1 and M2 in both olivines were determined and its Mössbauer hyperfine parameters were evaluated. Some differences in the tendencies of temperature dependence of spectral parameters and small variations of 57Fe quadrupole splitting in both M1 and M2 sites of olivines from Omolon and Seymchan were found. On the basis of Mössbauer parameters and chemical data, the temperatures of equilibrium cation distribution were evaluated for both olivines. © 2012 American Institute of Physics

    Enantioselective Total Synthesis of (+)-Cassiol

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    An enantioselective total synthesis of (+)-cassiol is reported. The complex derived from Pd-2(pmdba)(3) and enantiopure t-BuPHOX ligand catalyzes enantioconvergent decarboxylative alkylation to generate the quaternary carbon stereocenter at an early stage. The overall synthetic strategy involves a convergent late-stage coupling of two fragments. The synthesis features a longest linear sequence of eight steps

    Theoretical and experimental study of high-pressure synthesized B20-type compounds Mn1x_{1-x}(Co,Rh)x_xGe

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    The search and exploration of new materials not found in nature is one of modern trends in pure and applied chemistry. In the present work, we report on experimental and \textit{ab initio} density-functional study of the high-pressure-synthesized series of compounds Mn1x_{1-x}(Co,Rh)x_xGe. These high-pressure phases remain metastable at normal conditions, therewith they preserve their inherent noncentrosymmetric B20-type structure and chiral magnetism. Of particular interest in these two isovalent systems is the comparative analysis of the effect of 3d3d (Co) and 4d4d (Rh) substitution for Mn, since the 3d3d orbitals are characterized by higher localization and electron interaction than the 4d4d orbitals. The behavior of Mn1x_{1-x}(Co,Rh)x_xGe systems is traced as the concentration changes in the range 0x10 \leq x \leq 1. We applied a sensitive experimental and theoretical technique which allowed to refine the shape of the temperature dependencies of magnetic susceptibility χ(T)\chi(T) and thereby provide a new and detailed magnetic phase diagram of Mn1x_{1-x}Cox_xGe. It is shown that both systems exhibit a helical magnetic ordering that very strongly depends on the composition xx. However, the phase diagram of Mn1x_{1-x}Cox_xGe differs from that of Mn1x_{1-x}Rhx_xGe in that it is characterized by coexistence of two helices in particular regions of concentrations and temperatures.Comment: 12 pages, 11 figure

    ANALYSING ENVIRONMENTAL IMPLICATIONS OF ANTHROPOGENIC IMPACTS AS A RESULT OF SYZRAN SHALE-PROCESSING REFINERY WORK

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    Extraction and primary processing of natural minerals have a direct human impact on the lithosphere in the following way: the area of excavation and the area covered by rock dumps of overburden and substandard rocks increase; the landscape also changes. This problem occurs on all operated deposits and exists in out-of-operation deposits. This paper performs a critical analysis of environmental implications of anthropogenic impacts as a result of Syzran shale-processing refinery work Rock dumps parameters № 1 of Mine 3 and № 2 of Mine 5/6 of ZAO "Kashpirskaya Mine" are investigated. Rock dumps depth and surface ares, conservation volume and utilization capacity are considered to be landscape modifying parametres. The research demonstrates rock dumps parameters change in the period from 1950 to 2002. The paper evaluates the degree of anthropogenic impact of dumps territories and burnt rocks burials which were formed during the extraction of oil shale at Syzran shale-processing refinery. Those rock dumps resulted in the following transformation and change of the natural system and landscape: curvature of the slopes altered, soil and vegetation cover was dislocated. The only industry capable of reducing ecological tension in the region is building industry
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