1,968 research outputs found

    Properties of some five dimensional Einstein metrics

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    The volumes, spectra and geodesics of a recently constructed infinite family of five-dimensional inhomogeneous Einstein metrics on the two S3S^3 bundles over S2S^2 are examined. The metrics are in general of cohomogeneity one but they contain the infinite family of homogeneous metrics Tp,1T^{p,1}. The geodesic flow is shown to be completely integrable, in fact both the Hamilton-Jacobi and the Laplace equation separate. As an application of these results, we compute the zeta function of the Laplace operator on Tp,1T^{p,1} for large pp. We discuss the spectrum of the Lichnerowicz operator on symmetric transverse tracefree second rank tensor fields, with application to the stability of Freund-Rubin compactifications and generalised black holes.Comment: 1+43 pages, 2 figures, LaTeX. Minor typos correcte

    Structural analysis of silicon solar arrays

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    Engineering mechanics in structural design of silicon solar array

    Thermoelastic analysis of solar cell arrays and their material properties

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    Announced report discusses experimental test program in which five different solar cell array designs were evaluated by subjecting them to 60 thermal cycles from minus 190 deg to 0.0 deg. Results indicate that solder-coated cells combined with Kovar n-interconnectors and p-interconnectors are more durable under thermal loading than other configurations

    Mariner Venus 67 solar panel

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    Design, assembly, tests, and postflight analysis of Mariner Venus 67 solar pane

    Spatial and temporal cellular responses to single-strand breaks in human cells

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    DNA single-strand breaks (SSB) are one of the most frequent DNA lesions produced by reactive oxygen species and during DNA metabolism, but the analysis of cellular responses to SSB remains difficult due to the lack of an experimental method to produce SSB alone in cells. By using human cells expressing a foreign UV damage endonuclease (UVDE) and irradiating the cells with UV through tiny pores in membrane filters, we created SSB in restricted areas in the nucleus by the immediate action of UVDE on UV-induced DNA lesions. Cellular responses to the SSB were characterized by using antibodies and fluorescence microscopy. Upon UV irradiation, poly(ADP-ribose) synthesis occurred immediately in the irradiated area. Simultaneously, but dependent on poly(ADP-ribosyl)ation, XRCC1 was translocated from throughout the nucleus, including nucleoli, to the SSB. The BRCT1 domain of XRCC1 protein was indispensable for its poly(ADP-ribose)-dependent recruitment to the SSB. Proliferating cell nuclear antigen and the p150 subunit of chromatin assembly factor 1 also accumulated at the SSB in a detergent-resistant form, which was significantly reduced by inhibition of poly(ADP-ribose) synthesis. Our results show the importance of poly(ADP-ribosyl)ation in sequential cellular responses to SSB

    Chiral symmetry breaking and vacuum polarization in a bag

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    We study the effects of a finite quark mass in the hedgehog configuration in the two phase chiral bag model. We discuss the chiral properties, such as the fractional baryon number and the chiral Casimir energy, by using the Debye expansion for the analytical calculation and the Strutinsky's smearing method for the numerical computation. It is shown that the fractional baryon number carried by massive quarks in the vacuum is canceled by that in the meson sector. A finite term of the chiral Casimir energy is obtained with subtraction of the logarithmic divergence term

    Chiral symmetry breaking and stability of quark droplets

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    We discuss the stability of strangelets -- quark droplets with strangeness -- in the Nambu--Jona-Lasinio model supplemented by a boundary condition for quark confinement. Effects of dynamical chiral symmetry breaking are considered properly inside quark droplets of arbitrary baryon number. We obtain the energy per baryon number of quark droplets with baryon number from one to thousands. It is shown that strangelets are not the ground states as compared with nuclei, though they can be locally stable

    Performance of silicon solar cell assemblies

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    Solar cell assembly current-voltage characteristics, thermal-optical properties, and power performance were determined. Solar cell cover glass thermal radiation, optical properties, confidence limits, and temperature intensity effects on maximum power were discussed

    Boundary Value Problem for Black Rings

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    We study the boundary value problem for asymptotically flat stationary black ring solutions to the five-dimensional vacuum Einstein equations. Assuming the existence of two additional commuting axial Killing vector fields and the horizon topology of S1Ă—S2S^1\times S^2, we show that the only asymptotically flat black ring solution with a regular horizon is the Pomeransky-Sen'kov black ring solution.Comment: 21 pages, 1 figur

    Are Japanese and European gastric cancer the same biological entity? An immunohistochemical study.

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    To examine the suggested biological difference between Japanese and British gastric cancers, immunohistochemistry was used to demonstrate eight markers of biological activity in a matched series of 40 Japanese and 33 British cases. There were no differences in the proportions of Japanese and British tumours positive to epidermal growth factor, epidermal growth factor receptor, transforming growth factor alpha, cripto or p53. A significantly greater proportion of British tumours were positive to c-erbB-2 whilst a significantly greater proportion of Japanese tumours were positive to nm23. British tumours had a significantly greater mean proliferating cell nuclear antigen proliferation index than Japanese tumours. These differences could be clinically significant
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