29,706 research outputs found

    Gravitational Radiation from a Spinning Ellipsoid of Uniform Density

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    Gravitational radiation calculation of spinning ellipsoid of uniform density for estimation of energy loss rate of collapsing neutron sta

    Atomic and molecular matter fields in periodic potentials

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    This paper deals with the conversion between atoms and molecules in optical lattices. We show that in the absence of collisional interaction, the atomic and molecular components in different lattice wells combine into states with macroscopic condensate fractions, which can be observed as a strong diffraction signal, if the particles are abruptly released from the lattice. The condensate population, and the diffraction signal are governed not only by the mean number of atoms or molecules in each well, but by the precise amplitudes on state vector components with different numbers of particles. We discuss ways to control these amplitudes and to maximize the condensate fraction in the molecular formation process.Comment: Invited talk at 'Quantum Challenges', Falenty, Poland, Sep. 2003. Submitted to J. Mod. Op

    On the theory of polarization transfer in inhomogeneous magnetized plasmas

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    Polarization transfer theory in inhomogeneous magnetized plasmas with mode couplin

    Fourth Order Gradient Symplectic Integrator Methods for Solving the Time-Dependent Schr\"odinger Equation

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    We show that the method of splitting the operator eϵ(T+V){\rm e}^{\epsilon(T+V)} to fourth order with purely positive coefficients produces excellent algorithms for solving the time-dependent Schr\"odinger equation. These algorithms require knowing the potential and the gradient of the potential. One 4th order algorithm only requires four Fast Fourier Transformations per iteration. In a one dimensional scattering problem, the 4th order error coefficients of these new algorithms are roughly 500 times smaller than fourth order algorithms with negative coefficient, such as those based on the traditional Ruth-Forest symplectic integrator. These algorithms can produce converged results of conventional second or fourth order algorithms using time steps 5 to 10 times as large. Iterating these positive coefficient algorithms to 6th order also produced better converged algorithms than iterating the Ruth-Forest algorithm to 6th order or using Yoshida's 6th order algorithm A directly.Comment: 11 pages, 2 figures, submitted to J. Chem. Phy

    Calculation of symmetric and asymmetric vortex seperation on cones and tangent ogives based on discrete vortex models

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    An inviscid discrete vortex model, with newly derived expressions for the tangential velocity imposed at the separation points, is used to investigate the symmetric and asymmetric vortex separation on cones and tangent ogives. The circumferential locations of separation are taken from experimental data. Based on a slender body theory, the resulting simultaneous nonlinear algebraic equations in a cross-flow plane are solved with Broyden's modified Newton-Raphson method. Total force coefficients are obtained through momentum principle with new expressions for nonconical flow. It is shown through the method of function deflation that multiple solutions exist at large enough angles of attack, even with symmetric separation points. These additional solutions are asymmetric in vortex separation and produce side force coefficients which agree well with data for cones and tangent ogives

    Enhancement Glutathione Peroxidase Activity and α2-Macroglobulin Gene Expression of Macrobrachium Rosenbergii Fed with Aqueous Morinda Citrifolia Leaves Extract-Supplemented Diet

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    Morinda citrifolia, known commercially as noni is often used for enhance immunity, these plant rich of phenolic compound with antioxidant properties. In the present study, Macrobrachium rosenbergii were fed with diets containing of aqueous M. citrifolia leaves extract (AMLE) at 0.6, 4 and 6 g kg-1. Glutathione peroxidase (GPx) activity was conducted to measure immune parameter, these parameter was evaluated before and after 7, 21, 35, 49 and 63 days of feeding trial. Immune gene expression of α2-macroglubulin (α2-M) was evaluated in this study. The results showed that after 63 days of feeding treatment, significantly increased in GPx activity. Gene expressions of α2-macroglubulin was significantly upregulated. These results recommend that administration of AMLE can be used as an immunostimulant and regulated immune response and immune gene expression in M. rosenbergii

    GEODYN system description, volume 1

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    A computer program for the estimation of orbit and geodetic parameters is presented. The areas in which the program is operational are defined. The specific uses of the program are given as: (1) determination of definitive orbits, (2) tracking instrument calibration, (3) satellite operational predictions, and (4) geodetic parameter estimation. The relationship between the various elements in the solution of the orbit and geodetic parameter estimation problem is analyzed. The solution of the problems corresponds to the orbit generation mode in the first case and to the data reduction mode in the second case

    Intellectual Property Rights and North-South Trade

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    We study the incentive that a government in the South has to protect the intellectual property rights of Northern firms, and the consequences of the decision taken by the South for welfare in the North and for efficiency of the world equilibrium. We conduct our analysis in the context of a competition between a single Northern producer and a single Southern producer selling some good to an integrated world market. In this competition, only the Northern firm has the ability to conduct R&D in order to lower its production costs, but the Southern firm can imitate costlessly if patent protection for process innovations is not enforced by the government of the South. We find that the interests of the North and the South generally conflict in the matter of protection of intellectual property, with the South benefiting from the ability to pirate technology and the North harmed by such actions. A strong system of intellectual property rights may or may not enhance world efficiency.
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