29,336 research outputs found

    Design and Implementation of an RNS-based 2D DWT Processor

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    Relaxation of a Single Knotted Ring Polymer

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    The relaxation of a single knotted ring polymer is studied by Brownian dynamics simulations. The relaxation rate lambda_q for the wave number q is estimated by the least square fit of the equilibrium time-displaced correlation function to a double exponential decay at long times. The relaxation rate distribution of a single ring polymer with the trefoil knot appears to behave as lambda_q=A(1/N^)x for q=1 and lambda_q=A'(q/N)^x' for q=2 and 3, where x=2.61, x'=2.02 and A>A'. The wave number q of the slowest relaxation rate for each N is given by q=2 for small values of N, while it is given by q=1 for large values of N. This crossover corresponds to the change of the structure of the ring polymer caused by the localization of the knotted part to a part of the ring polymer.Comment: 13 pages, 5 figures, uses jpsj2.cl

    Tidal Interaction between a Fluid Star and a Kerr Black Hole in Circular Orbit

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    We present a semi-analytic study of the equilibrium models of close binary systems containing a fluid star (mass mm and radius R0R_0) and a Kerr black hole (mass MM) in circular orbit. We consider the limit MmM\gg m where spacetime is described by the Kerr metric. The tidally deformed star is approximated by an ellipsoid, and satisfies the polytropic equation of state. The models also include fluid motion in the stellar interior, allowing binary models with nonsynchronized stellar spin (as expected for coalescing neutron star-black hole binaries) to be constructed. Tidal disruption occurs at orbital radius rtideR0(M/m)1/3r_{\rm tide}\sim R_0(M/m)^{1/3}, but the dimensionless ratio r^tide=rtide/[R0(M/m)1/3]\hat r_{\rm tide}=r_{\rm tide}/[R_0(M/m)^{1/3}] depends on the spin parameter of the black hole as well as on the equation of state and the internal rotation of the star. We find that the general relativistic tidal field disrupts the star at a larger r^tide\hat r_{\rm tide} than the Newtonian tide; the difference is particularly prominent if the disruption occurs in the vicinity of the black hole's horizon. In general, r^tide\hat r_{\rm tide} is smaller for a (prograde rotating) Kerr black hole than for a Schwarzschild black hole. We apply our results to coalescing black hole-neutron star and black hole-white dwarf binaries. The tidal disruption limit is important for characterizing the expected gravitational wave signals and is relevant for determining the energetics of gamma ray bursts which may result from such disruption.Comment: 29 pages including 8 figures. Minor changes and update. To appear in ApJ, March 20, 2000 (Vol.532, #1

    Microwave imaging of mesoscopic percolating network in a manganite thin film

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    Many unusual behaviors in complex oxides are deeply associated with the spontaneous emergence of microscopic phase separation. Depending on the underlying mechanism, the competing phases can form ordered or random patterns at vastly different length scales. Using a microwave impedance microscope, we observed an orientation-ordered percolating network in strained Nd0.5Sr0.5MnO3 thin films with a large period of 100 nm. The filamentary metallic domains align preferentially along certain crystal axes of the substrate, suggesting the anisotropic elastic strain as the key interaction in this system. The local impedance maps provide microscopic electrical information of the hysteretic behavior in strained thin film manganites, suggesting close connection between the glassy order and the colossal magnetoresistance effects at low temperatures.Comment: 4 pages,4 figure

    Absence of a Role for Phosphorylation in the Tau Pathology of Alzheimer's Disease

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    Acknowledgments: Depolymerised bovine tubulin was kindly donated by J. Kilmartin (MRC Laboratory of Molecular Biology, Cambridge). This work was supported by the Medical Research Council (UK), a Wellcome Trust Studentship to RL, the Leopold Muller Estate, and the Newton Trust (Trinity College, Cambridge). We gratefully acknowledge Academic Books for permission to use Table 2 and Figures 2–4 which correspond to Table 1 and Figures 20–22 from Wischik C.M., Lai, R.Y.K. and Harrington, C.R. Modelling prion-like processing of tau protein in Alzheimer’s disease for pharmaceutical development, in Brain Microtubule Associated Proteins: Modifications in Disease, Avila, J.; Brandt, R.; Kosik, K.S., Eds. Harwood Academic Publishers: Amsterdam, The Netherlands, 1997. Erratum published on 12 August 2016, see Biomolecules 2016, 6(3), 35. http://www.mdpi.com/2218-273X/6/3/35Peer reviewedPublisher PD
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