9,258 research outputs found

    Dynamical Susceptibility in KDP-type Crysals above and below Tc II

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    The path probability method (PPM) in the tetrahedron-cactus approximation is applied to the Slater-Takagi model with dipole-dipole interaction for KH2PO4-type hydrogen-bonded ferroelectric crystals in order to derive a small dip structure in the real part of dynamical susceptibility observed at the transition temperature Tc. The dip structure can be ascribed to finite relaxation times of electric dipole moments responsible for the first order transition with contrast to the critical slowing down in the second order transition. The light scattering intensity which is related to the imaginary part of dynamical susceptibility is also calculated above and below the transition temperature and the obtained central peak structure is consistent with polarization fluctuation modes in Raman scattering experiments.Comment: 8 pages, 11 figure

    On Phase Transition of NH4H2PO4NH_{4}H_{2}PO_{4}-Type Crystals by Cluster Variation Method

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    The Cluster Variation Method (CVM) is applied to the Ishibashi model for ammonium dihydrogen phosphate (NH4H2PO4\rm NH_{4}H_{2}PO_{4}) of a typical hydrogen bonded anti-ferroelectric crystal. The staggered and the uniform susceptibility without hysteresis are calculated at equilibrium. On the other hand, by making use of the natural iteration method (NIM) for the CVM, hysteresis phenomena of uniform susceptibility versus temperature observed in experiments is well explained on the basis of local minimum in Landau type variational free energy. The polarization PP curves against the uniform field is also calculated.Comment: 14 pages, 10 figure

    Absence of contagious yawning in children with autism spectrum disorder

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    This study is the first to report the disturbance of contagious yawning in individuals with autism spectrum disorder (ASD). Twenty-four children with ASD as well as 25 age-matched typically developing (TD) children observed video clips of either yawning or control mouth movements. Yawning video clips elicited more yawns in TD children than in children with ASD, but the frequency of yawns did not differ between groups when they observed control video clips. Moreover, TD children yawned more during or after the yawn video clips than the control video clips, but the type of video clips did not affect the amount of yawning in children with ASD. Current results suggest that contagious yawning is impaired in ASD, which may relate to their impairment in empathy. It supports the claim that contagious yawning is based on the capacity for empathy

    Dynamical Susceptibility in KH2PO4-type Crystals above and below Tc

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    The time dependent cluster approximation called the path probability method (PPM) is applied to a pseudo-spin Ising Hamiltonian of the Slater-Takagi model for KH2PO4-type hydrogen-bonded ferroelectrics in order to calculate the homogeneous dynamical susceptibility above and below the ferroelectric transition temperature. Above the transition temperature all the calculations are carried out analytically in the cactus approximation of the PPM. Below the transition temperature the dynamical susceptibility is also calculated accurately since the analytical solution of spontaneous polarization in the ferroelectric phase can be utilized. When the temperature is approached from both sides of the transition temperature, only one of relaxation times shows a critical slowing down and makes a main contribution to the dynamical susceptibility. The discrepancy from Slater model (ice-rule limit) is discussed in comparison with some experimental data.Comment: 8 pages, 10 figure

    The current problems of the minimal SO(10) GUT and their solutions

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    This talk consists of two parts. In part I we review how the minimal renormalizable supersymmetric SO(10) model, an SO(10) framework with only one 10 and one 126 Higgs multiplets in the Yukawa sector, is attractive because of its highly predictive power. Indeed it not only gives a consistent predictions on neutrino oscillation data but also gives reasonable and interesting values for leptogenesis, LFV, muon g-2, neutrinoless double beta decay etc. However, this model suffers from problems related to running of gauge couplings. The gauge coupling unification may be spoiled due to the presence of Higgs multiplets much lighter than the grand unification (GUT) scale. In addition, the gauge couplings blow up around the GUT scale because of the presence of Higgs multiplets of large representations. In part II we consider the minimal SO(10) model in the warped extra dimension and show a possibility to solve these problems.Comment: 15 pages, 7 figures, Talk given at the International Workshop on Neutrino Masses and Mixings Toward Unified Understanding of Quarks and Lepton Mass Matrices, held at University of Shizuoka on December 17-19, 200

    Continuum Electromechanical Modeling of Protein-Membrane Interaction

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    A continuum electromechanical model is proposed to describe the membrane curvature induced by electrostatic interactions in a solvated protein-membrane system. The model couples the macroscopic strain energy of membrane and the electrostatic solvation energy of the system, and equilibrium membrane deformation is obtained by minimizing the electro-elastic energy functional with respect to the dielectric interface. The model is illustrated with the systems with increasing geometry complexity and captures the sensitivity of membrane curvature to the permanent and mobile charge distributions.Comment: 5 pages, 12 figure

    Cultural background modulates how we look at other persons' gaze

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    The current study investigated the role of cultural norms on the development of face-scanning. British and Japanese adults’ eye movements were recorded while they observed avatar faces moving their mouth, and then their eyes toward or away from the participants. British participants fixated more on the mouth, which contrasts with Japanese participants fixating mainly on the eyes. Moreover, eye fixations of British participants were less affected by the gaze shift of the avatar than Japanese participants, who shifted their fixation to the corresponding direction of the avatar’s gaze. Results are consistent with the Western cultural norms that value the maintenance of eye contact, and the Eastern cultural norms that require flexible use of eye contact and gaze aversion

    Specific heat of aluminium-doped superconducting silicon carbide

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    The discoveries of superconductivity in heavily boron-doped diamond, silicon and silicon carbide renewed the interest in the ground states of charge-carrier doped wide-gap semiconductors. Recently, aluminium doping in silicon carbide successfully yielded a metallic phase from which at high aluminium concentrations superconductivity emerges. Here, we present a specific-heat study on superconducting aluminium-doped silicon carbide. We observe a clear jump anomaly at the superconducting transition temperature 1.5 K indicating that aluminium-doped silicon carbide is a bulk superconductor. An analysis of the jump anomaly suggests BCS-like phonon-mediated superconductivity in this system.Comment: 4 pages, 2 figure
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