21,737 research outputs found

    Phase Diagram of Spinless Fermions on an Anisotropic Triangular Lattice at Half-filling

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    The strong coupling phase diagram of the spinless fermions on the anisotropic triangular lattice at half-filling is presented. The geometry of inter-site Coulomb interactions rules the phase diagram. Unconventional charge ordered phases are detected which are the recently reported pinball liquid and the striped chains. Both are induced by the quantum dynamics out of classical disordered states and afford extremely correlated metallic states and the particular domain wall-type of excitations, respectively. The disorder once killed by the quantum effect revives at the finite temperature, which is discussed in the terms of the organic θ\theta-ET2X_2X.Comment: 4pages 6figure

    Are Americans more Altruistic than the Japanese Comparison of Saving and Bequest Motives.

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    In this paper, we analyze a variety of data on saving motives, bequest motives, and bequest division from the "Comparative Survey of Savings in Japan and the United States", a binational survey conducted in 1996 by the Institute for Posts and Telecommunications Policy of the Ministry of Posts and Telecommunications of the Government of Japan, in order to shed light on which model of household behavior applies in the two countries.HOUSEHOLD ; SAVINGS ; CONSUMPTION

    Multiparameter quantum Schur duality of type B

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    We establish a Schur-type duality between a coideal subalgebra of the quantum group of type A and the Hecke algebra of type B with two parameters. We identify the ı\imath-canonical basis on the tensor product of the natural representation with Lusztig's canonical basis of the type B Hecke algebra with unequal parameters associated to a weight function

    Comparison between kinetic and fluid simulations of slab ion temperature gradient driven turbulence

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    A detailed comparison between kinetic and fluid simulations of collisionless slab ion temperature gradient driven turbulence is made. The nondissipative closure model (NCM) for linearly unstable modes, which is presented by Sugama, Watanabe, and Horton [Phys. Plasmas 8, 2617 (2001)], and the dissipative closure model by Hammett and Perkins (HP) [Phys. Rev. Lett. 64, 3019 (1990)] are used in separate fluid simulations. The validity of these closure models for quantitative prediction of the turbulent thermal transport is examined by comparing nonlinear results of the fluid simulations with those of the collisionless kinetic simulation of high accuracy. Simulation results show that, in the saturated turbulent state, the turbulent thermal diffusivity chi obtained from the HP model is significantly larger than the chi given by the NCM which is closer to chi measured in the kinetic simulation. Contrary to the dissipative form of the parallel heat flux closure relation assumed in the HP model, the NCM describes well the exact kinetic simulation, in which for some unstable wave numbers k, the imaginary part of the ratio of the parallel heat flux q_k to the temperature fluctuation T_k is a oscillatory function of time and sometimes takes positive values. The positive values of Im(q_k/T_k), imply the negative parallel heat diffusivity, correlate with the occasional inward heat flux occurring for the wave numbers k, and reduce the total chi

    Collisionless kinetic-fluid model of zonal flows in toroidal plasmas

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    A novel kinetic-fluid model is presented, which describes collisionless time evolution of zonal flows in tokamaks. In the new zonal-flow closure relations, the parallel heat fluxes are written by the sum of short- and long-time-evolution parts. The former part is given in the dissipative form of the parallel heat diffusion and relates to collisionless damping processes. The latter is derived from the long-time-averaged gyrocenter distribution and plays a major role in describing low-frequency or stationary zonal flows, for which the parallel heat fluxes are expressed in terms of the parallel flow as well as the nonlinear-source and initial-condition terms. It is shown analytically and numerically that, when applied to the zonal flow driven by either ion or electron temperature gradient turbulence, the kinetic-fluid equations including the new closure relations can reproduce the same long-time zonal-flow responses to the initial condition and to the turbulence source as those obtained from the gyrokinetic model

    Collisionless kinetic-fluid closure and its application to the three-mode ion temperature gradient driven system

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    A novel closure model is presented to give a set of fluid equations which describe a collisionless kinetic system. In order to take account of the time reversal symmetry of the collisionless kinetic equation, the new closure model relates the parallel heat flux to the temperature and the parallel flow in terms of the real-valued coefficients in the unstable wave number space. Effects of the closure model on turbulence saturation and anomalous transport are investigated based on kinetic and fluid entropy balances. When the closure model is applied to the three-mode ion temperature gradient (ITG) driven system, the fluid system of equations reproduces the exact nonlinear kinetic solution found by Watanabe, Sugama, and Sato [Phys. Plasmas 7, 984 (2000)]. Oscillatory behaviors and initial amplitude dependence of other numerical kinetic solutions of the three-mode ITG problem can also be accurately described by the fluid system

    Influence of the Varus-Valgus Instability of the Contact of the Femora-Tibial Joint

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    Knee joint instability may occur in rupture of ligaments, especially of the anterior cruciate ligament (ACL) (Inouc et ai, 1987). Also in Charcot's joint, with loss of synergistic reflexes and deep sensation loss, the muscles and stretched ligaments cannot retain normal alignment and stability of the joint. This in turn results in faulty weight bearing with excessive stress upon the articular surfaces and in destruction of the joint (Katz et ai, 1961). To assess the changes in articular surface contact of the unstable knee joint, the contact pressures of the femoro-tibial joint with varus or valgus alignment were measured using a newly developed system

    Restoration of isotropy on fractals

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    We report a new type of restoration of macroscopic isotropy (homogenization) in fractals with microscopic anisotropy. The phenomenon is observed in various physical setups, including diffusions, random walks, resistor networks, and Gaussian field theories. The mechanism is unique in that it is absent in spaces with translational invariance, while universal in that it is observed in a wide class of fractals.Comment: 11 pages, REVTEX, 3 postscript figures. (Compressed and encoded figures archived by "figure" command). To appear in Physical Review Letter
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