著者

Chiba Ayano Funamori Nobumasa Nakayama Kazuya Ohishi Yasuo Bennington Stephen Rastogi Sanjay Shukla Anuj Tsuji Kazuhiko Takenaka Mikihito

出版者

American Physical Society

雑誌

Physical Review E (ISSN:15393755)

巻号頁・発行日

vol.85, no.2, 2012-02

被引用文献数

20

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溶融高分子の新しい構造変化を発見-加圧によるナノスケールの構造変化-. 京都大学プレスリリース. 2012-02-28.

著者

Charbonneau P. Ikeda A. Meel J. A. van Miyazaki K.

出版者

American Physical Society

雑誌

Physical review E (ISSN:15393755)

巻号頁・発行日

vol.81, no.04, pp.040501, 2010-04

被引用文献数

30 13

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There exists a variety of theories of the glass transition and many more numerical models. But because the models need built-in complexity to prevent crystallization, comparisons with theory can be difficult. We study the dynamics of a deeply supersaturated monodisperse four-dimensional (4D) hard-sphere fluid, which has no such complexity, but whose strong intrinsic geometrical frustration inhibits crystallization, even when deeply supersaturated. As an application, we compare its behavior to the mode-coupling theory (MCT) of glass formation. We find MCT to describe this system better than any other structural glass formers in lower dimensions. The reduction in dynamical heterogeneity in 4D suggested by a milder violation of the Stokes-Einstein relation could explain the agreement. These results are consistent with a mean-field scenario of the glass transition.

著者

Kiyono Ken Konno Hidetoshi

出版者

American Physical Society

雑誌

Physical review E (ISSN:15393755)

巻号頁・発行日

vol.87, no.5, pp.052104, 2013-05

被引用文献数

9 3

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As a possible generalization of Beck-Cohen superstatistical processes, we study non-Gaussian processes with temporal heterogeneity of local variance. To characterize the variance heterogeneity, we define log-amplitude cumulants and log-amplitude autocovariance and derive closed-form expressions of the log-amplitude cumulants for χ2, inverse χ2, and log-normal superstatistical distributions. Furthermore, we show that χ2 and inverse χ2 superstatistics with degree 2 are closely related to an extreme value distribution, called the Gumbel distribution. In these cases, the corresponding superstatistical distributions result in the q-Gaussian distribution with q=5/3 and the bilateral exponential distribution, respectively. Thus, our finding provides a hypothesis that the asymptotic appearance of these two special distributions may be explained by a link with the asymptotic limit distributions involving extreme values. In addition, as an application of our approach, we demonstrated that non-Gaussian fluctuations observed in a stock index futures market can be well approximated by the χ2 superstatistical distribution with degree 2.

著者

Suda Yusuke Okuda Koji

出版者

American Physical Society (APS)

雑誌

Physical review E (ISSN:15393755)

巻号頁・発行日

vol.92, no.6, 2015-12-14

被引用文献数

35

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Chimera states in the systems of nonlocally coupled phase oscillators are considered stable in the continuous limit of spatially distributed oscillators. However, it is reported that in the numerical simulations without taking such limit, chimera states are chaotic transient and finally collapse into the completely synchronous solution. In this Rapid Communication, we numerically study chimera states by using the coupling function different from the previous studies and obtain the result that chimera states can be stable even without taking the continuous limit, which we call the persistent chimera state.

著者

Mizuno Hideyuki Yamamoto Ryoichi

出版者

The American Physical Society

雑誌

Physical Review E (ISSN:15393755)

巻号頁・発行日

vol.82, no.3, 2010-09

被引用文献数

17

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We numerically examine dynamical heterogeneity in a highly supercooled three-dimensional liquid via molecular-dynamics simulations. To define the local dynamics, we consider two time intervals: τα and τngp. τα is the α relaxation time, and τngp is the time at which non-Gaussian parameter of the Van Hove self-correlation function is maximized. We determine the lifetimes of the heterogeneous dynamics in these two different time intervals, τhetero(τα) and τhetero(τngp), by calculating the time correlation function of the particle dynamics, i.e., the four-point correlation function. We find that the difference between τhetero(τα) and τhetero(τngp) increases with decreasing temperature. At low temperatures, τhetero(τα) is considerably larger than τα, while τhetero(τngp) remains comparable to τα. Thus, the lifetime of the heterogeneous dynamics depends strongly on the time interval.

著者

Jizba Petr Arimitsu Toshihico

出版者

American Physical Society

雑誌

Physical review E (ISSN:15393755)

巻号頁・発行日

vol.69, no.2, pp.026128, 2004-02

被引用文献数

51 26

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Despite recent claims we argue that Rényi’s entropy is an observable quantity. It is shown that, contrary to popular belief, the reported domain of instability for Rényi entropies has zero measure (Bhattacharyya measure). In addition, we show that the instabilities can be easily emended by introducing a coarse graining into an actual measurement. We also clear up any doubts regarding the observability of Rényi’s entropy in (multi)fractal systems and in systems with absolutely continuous probability density functions.

著者

Nomura Shintaro Iitaka Toshiaki

出版者

American Physical Society

雑誌

Physical review E (ISSN:15393755)

巻号頁・発行日

vol.76, no.3, pp.037701, 2007-09

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A linear scale method for calculating electronic properties of large and complex systems is introducedwithin a local density approximation. The method is based on the Chebyshev polynomialexpansion and the time-dependent method, which is tested on the calculation of the electronicstructure of a model n-type GaAs quantum dot.