457 research outputs found

    Geological-morphological description of the Sedna and Guinevre planitiae on Venus (photomap sheets B-11, B-20, B-21)

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    Presented are descriptions and maps of the region of Sedna and Guinevra Planitiae--representatives of the largest geological providense on Venus comprised of volcanic rock. Units of different age are isolated and their relations are given, as well as interpretations of proposed mechanisms of formation

    Spin excitations of the correlated semiconductor FeSi probed by THz radiation

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    By direct measurements of the complex optical conductivity σ(ν)\sigma(\nu) of FeSi we have discovered a broad absorption peak centered at frequency ν0(4.2K)32cm1\nu_{0}(4.2 K) \approx 32 cm^{-1} that develops at temperatures below 20 K. This feature is caused by spin-polaronic states formed in the middle of the gap in the electronic density of states. We observe the spin excitations between the electronic levels split by the exchange field of He=34±6TH_{e}=34\pm 6 T. Spin fluctuations are identified as the main factor determining the formation of the spin polarons and the rich magnetic phase diagram of FeSi.Comment: 5 pages, 4 figure

    Optical conductivity and penetration depth in MgB2

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    The complex conductivity of a MgB2 film has been investigated in the frequency range 4 cm^{-1}< nu < 30 cm^{-1} and for temperatures 2.7 K < T <300 K. The overall temperature dependence of both components of the complex conductivity is reminiscent of BCS-type behavior, although a detailed analysis reveals a number of discrepancies. No characteristic feature of the isotropic BCS gap temperature evolution is observed in the conductivity spectra in the superconducting state. A peak in the temperature dependence of the real part of the conductivity is detected for frequencies below 9 cm^{-1}. The superconducting penetration depth follows a T^2 behavior at low temperatures.Comment: 4 pages, 4 figure

    Geological-morphological description of the Ishtar Terra (photomap of the Venusian surface sheet B-5)

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    The main part of the Ishtar Terra east of the Maxwell Montes is covered with systems of areal dislocations of several directions, which are called Parquet. According to the structural patterns these may be divided into: (1) the central stable block; (2) the lesser peripheral blocks separated from the central one by gaps and grabens; (3) the zones of mobilized parquet, whose substance flowed downward at an incline in the directions away from the central block in the form of plastic flows; and (4) the partially parqueted lava sheets. The Maxwell Montes were formed as a result of the collision between the central parquet block and the Lakshmi Planum

    Renormalization of the asymptotically expanded Yang-Mills spectral action

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    We study renormalizability aspects of the spectral action for the Yang-Mills system on a flat 4-dimensional background manifold, focusing on its asymptotic expansion. Interpreting the latter as a higher-derivative gauge theory, a power-counting argument shows that it is superrenormalizable. We determine the counterterms at one-loop using zeta function regularization in a background field gauge and establish their gauge invariance. Consequently, the corresponding field theory can be renormalized by a simple shift of the spectral function appearing in the spectral action. This manuscript provides more details than the shorter companion paper, where we have used a (formal) quantum action principle to arrive at gauge invariance of the counterterms. Here, we give in addition an explicit expression for the gauge propagator and compare to recent results in the literature.Comment: 28 pages; revised version. To appear in CMP. arXiv admin note: substantial text overlap with arXiv:1101.480

    QUINQUESERIALIS QUINQUESERIALIS - SPECIFIC PARASITE OF MUSKRAT, AND ITS INFLUENCE ON SOME HEMATOLOGIC PARAMETERS OF THE HOST

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    Data on infection of muskrat by trematoda species Quinqueserialis quinqueserialis in the Selenga River Delta are presented in this paper. The indexes of infection of muskrat by parasite in 2011 are similar to those in 1981 and 1982. The study is the first attempt to assess the influence of infestation on structure and. quantity leucocytes of blood of infected muskrat in Lake Baikal basin

    Dual-comb thin-disk oscillator

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    The Competition between Staggered Field and Antiferromagnetic Interactions in Cugeo3:Fe

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    The EPR spectra along different crystallographic axes for single crystals of CuGeO3 containing 1% of Fe impurity have been studied in the frequency range 60-360 GHz at temperatures 0.5-30 K. The analysis based on the Oshikawa-Affleck (OA) theory suggests that the temperature dependences of the line width and g-factor are formed as a result of the competition between interchain antiferromagnetic interactions and staggered Zeeman energy. It is found that staggered magnetic moments in CuGeO3:Fe are located predominantly along b axis.Comment: 9 pages, 4 figures; submitted to QSS04 symposiu
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