563 research outputs found

    Stochastic Process Associated with Traveling Wave Solutions of the Sine-Gordon Equation

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    Stochastic processes associated with traveling wave solutions of the sine-Gordon equation are presented. The structure of the forward Kolmogorov equation as a conservation law is essential in the construction and so is the traveling wave structure. The derived stochastic processes are analyzed numerically. An interpretation of the behaviors of the stochastic processes is given in terms of the equation of motion.Comment: 12 pages, 9 figures; corrected typo

    Disability Prevention Programs for Older People: Factors Associated with Medical and Nursing Care Costs

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    This study aimed to clarify factors associated with medical and nursing care costs for older people living in community and to suggest an effective disability prevention programs. Total of participants in this study was 83 individuals (29 men and 54 women; mean age 81.2 ± 6.3 years old) on November 1st – December 28th, 2014. This study compared the average medical and nursing care costs per month with national average for those aged ≥ 65 years old. Logistic regression test was conducted to examine its association with medical and nursing care costs. Those who had outing activities ≥ 3 times a week were approximately three times less likely to reduce medical and nursing care costs than those who had outing activities < 3 times a week despite three controlled covariates (OR = 3.23 and 95% CI = 1.03 – 10.42). Disability prevention programs that improve frequency of outing at least three times in a week may become a valid economic approach to older people who do not live in nursing home

    Exact results on the dynamics of multi-component Bose-Einstein condensate

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    We study the time-evolution of the two dimensional multi-component Bose-Einstein condensate in an external harmonic trap with arbitrary time-dependent frequency. We show analytically that the time-evolution of the total mean-square radius of the wave-packet is determined in terms of the same solvable equation as in the case of a single-component condensate. The dynamics of the total mean-square radius is also the same for the rotating as well as the non-rotating multi-component condensate. We determine the criteria for the collapse of the condensate at a finite time. Generalizing our previous work on a single-component condensate, we show explosion-implosion duality in the multi-component condensate.Comment: Two-column 6 pages, RevTeX, no figures(v1); Added an important reference, version to appear in Physical Review A (v2

    Ambient Conditions of Winter Thunderstorms in Japan to Reproduce Observed Gamma‐Ray Glow Energy Spectra

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    Electric field of thunderclouds modifies components and energy spectra of the cosmic-ray air shower. In particular, thunderstorms accelerate charged particles, resulting in an enhancement of gamma-ray fluxes on the ground, known as a gamma-ray glow. This phenomenon has been observed in recent years by the Gamma-Ray Observation of Winter THunderclouds collaboration from winter thunderstorms in the Hokuriku area of Japan. The present work examines the ambient conditions required to produce spectral features of the previously detected gamma-ray glows, by using Monte Carlo simulations of particle interactions in the atmosphere. We focus on three parameters, the strength and length of the electric field, and the length of a null-field attenuation region below the electrified region. The average spectrum of observed gamma-ray glows in winter thunderstorms of Japan requires an electric field intensity close to 0.31 MV/m, slightly exceeding the Relativistic Runaway Electron Avalanche threshold of 0.284 MV/m. The vertical size of the electric field region should be comparable to 1 km. The estimated attenuation region size is 300–500 m, necessary to reduce the low-energy photon flux of the average gamma-ray glows. There is still a wide range of acceptable parameter sets with degeneracy to make a similar spectrum

    Stability analysis of the D-dimensional nonlinear Schroedinger equation with trap and two- and three-body interactions

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    Considering the static solutions of the D-dimensional nonlinear Schroedinger equation with trap and attractive two-body interactions, the existence of stable solutions is limited to a maximum critical number of particles, when D is greater or equal 2. In case D=2, we compare the variational approach with the exact numerical calculations. We show that, the addition of a positive three-body interaction allows stable solutions beyond the critical number. In this case, we also introduce a dynamical analysis of the conditions for the collapse.Comment: 6 pages, 7 figure

    18F-Fluoro-2\u27-Deoxyuridine and Experimental Brain Tumor

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    開始ページ、終了ページ: 冊子体のページ付

    Solutions of Gross-Pitaevskii equations beyond the hydrodynamic approximation: Application to the vortex problem

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    We develop the multiscale technique to describe excitations of a Bose-Einstein condensate (BEC) whose characteristic scales are comparable with the healing length, thus going beyond the conventional hydrodynamical approximation. As an application of the theory we derive approximate explicit vortex and other solutions. The dynamical stability of the vortex is discussed on the basis of the mathematical framework developed here, the result being that its stability is granted at least up to times of the order of seconds, which is the condensate lifetime. Our analytical results are confirmed by the numerical simulations.Comment: To appear in Phys. Rev.
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