40,346 research outputs found

    Direct Evidence from Spitzer for a low-luminosity AGN at the center of the Elliptical Galaxy NGC 315

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    We present the {\it Spitzer} Space Telescope InfraRed Array Camera (IRAC) and Multiband Imaging Photometer (MIPS) observations of the elliptical galaxy NGC 315. After removal of the host galaxy's stellar emission, we detected for the first time an infrared-red nucleus in NGC 315. We measured the spectral energy distribution (SED) for this active nucleus with wavelength range covering from radio to X-ray, and obtained the bolometric luminosity of Lbol≈1.9×1043ergss−1\rm L_{bol} \approx 1.9 \times 10^{43} ergs s^{-1}, corresponding to an extremely low Eddington ratio (L/LEdd_{\rm Edd}) of 4.97 ×\times 10−4^{-4}. Our results confirm that the physical nature of the nucleus of NGC 315 is a low-luminosity AGN, consistent with the recent optical and {\it Chandra} X-ray observations.Comment: 4 pages, accepted for publication in ApJ Letter

    Extremely Correlated Fermi Liquid Description of Normal State ARPES in Cuprates

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    The normal state single particle spectral function of the high temperature superconducting cuprates, measured by the angle resolved photoelectron spectroscopy (ARPES), has been considered both anomalous and crucial to understand. Here we show that an unprecedentedly detailed description of the data is provided by a spectral function arising from the Extremely Correlated Fermi Liquid state of the t-J model proposed recently by Shastry. The description encompasses both laser and conventional synchrotron ARPES data on optimally doped Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta}, and also conventional synchrotron ARPES data on the La1.85_{1.85}Sr0.15_{0.15}CuO4_4 materials. {\em It fits all data sets with the same physical parameter values}, satisfies the particle sum rule and successfully addresses two widely discussed "kink" anomalies in the dispersion.Comment: Published version, 5 figs; published 29 July (2011

    A Cosmological Model with Dark Spinor Source

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    In this paper, we discuss the system of Friedman-Robertson-Walker metric coupling with massive nonlinear dark spinors in detail, where the thermodynamic movement of spinors is also taken into account. The results show that, the nonlinear potential of the spinor field can provide a tiny negative pressure, which resists the Universe to become singular. The solution is oscillating in time and closed in space, which approximately takes the following form g_{\mu\nu}=\bar R^2(1-\delta\cos t)^2\diag(1,-1,-\sin^2r ,-\sin^2r \sin^2\theta), with Rˉ=(1∼2)×1012\bar R= (1\sim 2)\times 10^{12} light year, and δ=0.96∼0.99\delta=0.96\sim 0.99. The present time is about t∼18∘t\sim 18^\circ.Comment: 13 pages, no figure, to appear in IJMP

    Distribution of endothelial cell protein C/activated protein C receptor (EPCR) during mouse embryo development.

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    The endothelial cell protein C receptor (EPCR) augments protein C activation by the thrombomodulin.thrombin complex. Deletion of the EPCR gene in mice has been reported to lead to embryonic lethality before embryonic day 10 (E10.0). To identify potential mechanisms responsible for this lethality, we performed an immunohistological analysis of EPCR distribution during mouse embryogenesis. EPCR was detected in the trophoblast giant cells at the feto-maternal boundary from E7.5 and at later time points in the trophoblasts of the placenta, suggesting a role in the haemostatic regulation of the maternal blood that irrigates these surfaces. In the embryo, EPCR was weakly detected in aortic endothelial cells from E13.5. Thereafter, EPCR levels increased in certain large blood vessels endothelial cells suggesting that the specificity of EPCR to large vessels is conferred in utero. However, not until postnatal day 7 did the intensity and distribution of EPCR staining mimic that observed in adult mice

    An advanced meshless method for time fractional diffusion equation

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    Recently, because of the new developments in sustainable engineering and renewable energy, which are usually governed by a series of fractional partial differential equations (FPDEs), the numerical modelling and simulation for fractional calculus are attracting more and more attention from researchers. The current dominant numerical method for modeling FPDE is Finite Difference Method (FDM), which is based on a pre-defined grid leading to inherited issues or shortcomings including difficulty in simulation of problems with the complex problem domain and in using irregularly distributed nodes. Because of its distinguished advantages, the meshless method has good potential in simulation of FPDEs. This paper aims to develop an implicit meshless collocation technique for FPDE. The discrete system of FPDEs is obtained by using the meshless shape functions and the meshless collocation formulation. The stability and convergence of this meshless approach are investigated theoretically and numerically. The numerical examples with regular and irregular nodal distributions are used to validate and investigate accuracy and efficiency of the newly developed meshless formulation. It is concluded that the present meshless formulation is very effective for the modeling and simulation of fractional partial differential equations
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