317 research outputs found

    Molecular Dynamics of Yukawa System using the Fast Multipole Method

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    In order to perform the large-scale molecular dynamics simulation of the Yukawa system, a mathematical expression for molecular dynamics using the fast multipole method is described. The model simulations are also performed to test the performance of our implementation of the FMM

    Structure and Cohesive Energy of Large Spherical Coulomb Clusters

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    The ground state of spherical clusters of charged particles of one species confined by the three-dimensional parabolic potential is investigated by molecular dynamics simulations with the system size from N = 5000 to N = 1.2 × 10(5) . The cohesive energy per particle is compared between the shell-structured clusters and spherical finite bcc lattices with relaxed surfaces, the former and the latter being the ground states for small systems and for the large enough systems, respectively. It is shown that, when N > N(c)(N(c) > N), finite bcc lattices with relaxed surfaces (the shell structures) have stronger cohesion than the shell structures (finite bcc lattices with relaxed surfaces) and the critical value of the transition N(c) is estimated to be 10(4) < N(c) < 1.4 × 10(4) . The nucleation of the bcc lattice in the shell-structured cluster of 2 × 10(4) ions is observed

    Multi-scale interactions between turbulence and magnetohydrodynamic instability driven by energetic particles

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    In order to realize high performance burning plasmas in magnetic-confinement fusion devices, such as tokamaks, both bulk plasma transport and that of energetic fusion alpha-particles, which result from different scale fluctuations with different free energy sources, have to be reduced simultaneously. Utilizing the advantage of global toroidal non-linear simulations covering a whole torus, here, we found a new coupling mechanism between the low-frequency micro-scale electromagnetic drift-wave fluctuations regulating the former, while the high-frequency macro-scale toroidal Alfven eigenmode (TAE) regulates the latter. This results from the dual spread of micro-scale turbulence due to the macro-scale TAE not only in wavenumber space representing local eddy size but also in configuration space with global profile variations. Consequently, a new class of turbulent state is found to be established, where the turbulence is homogenized on the poloidal cross-section with exhibiting large-scale structure, which increases fluctuation levels and then both transports, leading to deterioration in the fusion performance

    On simulations of strong evaporation flows of a vapor from its plane condensed phase with finite thermal conductivity -Method of application of the Fluid Dynamic Formulation as the governing system-

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    Flow problems associated with phase change processes even if they are within the range of the continuum limit have to be dealt with based on the kinetic equations because the nonequilibrium nature of the Knudsen layer, which is always existent in the close vicinity of the interface, is the cause for the phase-change processes to occur at the interface. Recently, a new governing system of equations has been proposed by Onishi et. al. to deal with at the ordinary fluid dynamic level various flow problems, transient to steady, due to phase change processes. This new system, called the Fluid Dynamic Formulation, can be used as the substitute of the kinetic equations for the analyses of flow problems of such kind. However, the method of application of this new governing system is not so straightforwad as is expected. The present paper will show 1) how to use the Fluid Dynamic Formulation as the governing system of equations in place of the kinetic system by taking up simple one-dimensional problems and 2) the approriateness of the results obtained by comparison with the corresponding results obtained based on the kinetic system

    A Dynamic Analysis of the Green Electricity Fund:Threshold Models Revisited

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    This study applies a threshold model proposed by Granovetter (1978) to analyze the dynamic diffusion process of donating behavior for renewable energy. Using data on people's willingness to donate for renewable energy under various predicted participation rates, we simulate how herd behavior spreads and the participation rate reaches the equilibrium. The participation rate at the equilibrium is estimated as 66.46% when the suggested donation is 500 yen, while it is 25.88% when the suggested amount is 1,000 yen. The influence of environmentalism and altruism is also examined, and we find that these motivations increase the participation rate 43.38% on average.Green electricity fund; Dynamic analysis; Contingent Valuation; Threshold model

    Small energy scattering for the Zakharov system with radial symmetry

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    We prove small energy scattering for the 3D Zakharov system with radial symmetry. The main ingredients are normal form reduction and the radial-improved Strichartz estimates.Comment: 11 pages, corrected minor errors, published online in IMRN. arXiv admin note: text overlap with arXiv:1208.165

    体の痛み、社会的支援、抑うつ状態、脳血管疾患は独立して高齢者の睡眠障害と関連する : 藤原京スタディ横断解析

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    OBJECTIVE: To investigate independent effects of various factors associated with sleep disturbance among community-dwelling elderly individuals. METHODS: We analyzed data obtained from 3732 individuals aged ≥65 years who responded to a self-administered questionnaire and participated in a structured interview which assessed the Pittsburgh Sleep Quality Index (PSQI), subjective bodily pain, the Jichi Medical School Social Support Scale, the Geriatric Depression Scale (GDS-15), health status, and demographic characteristics. Sleep disturbance was defined as a global PSQI score >5.5, which was used as a dependent variable in multiple logistic regression analysis to determine adjusted odds ratios (ORs) and 95 % confidence intervals (CIs) of related factors. RESULTS: We identified a significant increase in the adjusted ORs for female (OR 1.56, 95 % CI 1.34-1.83), age ≥80 years (1.31, 1.01-1.69), history of stroke (1.44, 1.08-1.92), and a GDS-15 score ≥6 as compared to 0-2 (2.29, 1.86-2.81), with regard to sleep disturbance. Participants with severe or very severe bodily pain had the highest adjusted OR (3.00, 2.15-4.19), and those with very mild bodily pain also had a relatively high OR (1.30, 1.06-1.60), relative to those without subjective bodily pain. In addition, compared with participants with strong social support from spouse or family, those with weak social support had significantly increased adjusted ORs (1.21, 1.01-1.44, 1.44, 1.23-1.70, respectively). CONCLUSIONS: The present study indicates that sleeping disturbances among the elderly are closely associated with social support from a spouse and family. They are also associated with pain, even at stages in which subjective bodily pain is very mild.博士(医学)・乙第1381号・平成28年9月28日© The Japanese Society for Hygiene 2016The final publication is available at Springer via http://dx.doi.org/10.1007/s12199-016-0529-

    Natriuretic Peptide Signaling via Guanylyl Cyclase (GC)-A: An Endogenous Protective Mechanism of the Heart

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    Atrial and brain natriuretic peptides (ANP and BNP, respectively) are cardiac hormones, secretions of which are markedly upregulated during cardiac failure, making their plasma levels clinically useful diagnostic markers. ANP and BNP exert potent diuretic, natriuretic and vasorelaxant effects, which are mediated via their common receptor, guanylyl cyclase (GC)-A (also called natriuretic peptide receptor (NPR)-A). Mice deficient for GC-A are mildly hypertensive and show marked cardiac hypertrophy and fibrosis that is disproportionately severe, given their modestly higher blood pressure. Indeed, the cardiac hypertrophy seen in these mice is enhanced in a blood pressure-independent manner and is suppressed by cardiomyocyte-specific overexpression of GC-A. These results suggest that the actions of a local cardiac ANP/BNP-GC-A system are essential for maintenance of normal cardiac architecture. In addition, GC-A was shown to exert its cardioprotective effects by inhibiting angiotensin II-induced hypertrophic signaling, and recent evidence suggests that regulator of G protein signaling (RGS) subtype 4 is involved in the GC-A-mediated inhibition of Gαq-coupled hypertrophic signal transduction. Furthermore, several different groups have reported that functional mutations in the promoter region of the human GC-A gene are associated with essential hypertension and ventricular hypertrophy. These findings suggest that endogenous GC-A protects the heart from pathological hypertrophic stimuli, and that humans who express only low levels of GC-A are genetically predisposed to cardiac remodeling and hypertension
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