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Search Results: 1 - 10 of 3808 matches for " Shigeaki Sato "
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"Topological" Formulation of Effective Vortex Strings
Masatoshi Sato,Shigeaki Yahikozawa
Physics , 1994, DOI: 10.1016/0550-3213(94)00531-I
Abstract: We present a ``topological'' formulation of arbitrarily shaped vortex strings in four dimensional field theory. By using a large Higgs mass expansion, we then evaluate the effective action of the closed Abrikosov-Nielsen-Olesen vortex string. It is shown that the effective action contains the Nambu-Goto term and an extrinsic curvature squared term with negative sign. We next evaluate the topological $\FtF$ term and find that it becomes the sum of an ordinary self-intersection number and Polyakov's self-intersection number of the world sheet swept by the vortex string. These self-intersection numbers are related to the self-linking number and the total twist number, respectively. Furthermore, the $\FtF$ term turns out to be the difference between the sum of the writhing numbers and the linking numbers of the vortex strings at the initial time and the one at the final time. When the vortex string is coupled to fermions, the chiral fermion number of the vortex string becomes the writhing number (modulo $\bZ$) through the chiral anomaly. Our formulation is also applied to ``global'' vortex strings in a model with a broken global $U(1)$ symmetry.
Discovery of Characteristic Patterns from Transactions with Their Classes
Shigeaki Sakurai
Applied Computational Intelligence and Soft Computing , 2012, DOI: 10.1155/2012/786387
Abstract: This paper deals with transactions with their classes. The classes represent the difference of conditions in the data collection. This paper redefines two kinds of supports: characteristic support and possible support. The former one is based on specific classes assigned to specific patterns. The latter one is based on the minimum class in the classes. This paper proposes a new method that efficiently discovers patterns whose characteristic supports are larger than or equal to the predefined minimum support by using their possible supports. Also, this paper verifies the effect of the method through numerical experiments based on the data registered in the UCI machine learning repository and the RFID (radio frequency identification) data collected from two apparel shops. 1. Introduction Owing to the progress of computer environment and network environment, we can easily collect large amount of data and cheaply store it. We believe that the data includes useful knowledge which can help our decision making. Many researchers tackle on the discovery of the knowledge from the data since the mid-1990s. Various discovery tasks are studied in order to deal with various kinds of data. The discovery task of frequent patterns composed of items from transactions is one of the tasks. Each transaction is composed of an item set. In the retail field, a receipt and a sales item correspond to a transaction and an item, respectively. In the initial researches, [1] proposes a method that efficiently generates candidate patterns and discovers frequent patterns by using the Apriori property. Here, the property shows that the frequencies of patterns monotonically decrease as items composing the patterns increase. Reference [2] proposes a bitmap index, [3] proposes a vertical ID list, and [4] proposes a frequent pattern tree (FP-tree) in order to speedily access the transactions and efficiently calculate the frequencies of the patterns. It is possible for these improvements to speedily discover the frequent patterns. However, the discovered frequent patterns are not always the ones that are attractive for analysts. The discovery of patterns with different features is tried. For example, [5] tries to discover patterns whose orders based on the frequency are higher than the predefined order. Reference [6] does closed patterns representing many frequent patterns. Reference [7] does long patterns including many items. Reference [8] does patterns reflecting weights of items. Reference [9] does patterns reflecting hierarchical relationships among items. It is anticipated that more
First-Principles Molecular Dynamics Calculations of the Equation of State for Tantalum
Shigeaki Ono
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10104342
Abstract: The equation of state of tantalum (Ta) has been investigated to 100 GPa and 3,000 K using the first-principles molecular dynamics method. A large volume dependence of the thermal pressure of Ta was revealed from the analysis of our data. A significant temperature dependence of the calculated effective Grüneisen parameters was confirmed at high pressures. This indicates that the conventional approach to analyze thermal properties using the Mie-Grüneisen approximation is likely to have a significant uncertainty in determining the equation of state for Ta, and that an intrinsic anharmonicity should be considered to analyze the equation of state.
The Lehmann Discontinuity Due to Dehydration of Subducted Sediment
Shigeaki Ono
The Open Mineralogy Journal , 2007, DOI: 10.2174/18744567000701010001]
Abstract: Recent high-pressure experiments have led to the conclusion that water release from subducted sediments lying under continents in subduction regions occurs at about 220 km depth. This dehydration reaction is in good agreement with the seismological signature of the discontinuity indicating that sediment dehydration causes the Lehmann discontinuity in the upper mantle.
Elastic Properties of CaSiO3 Perovskite from ab initio Molecular Dynamics
Shigeaki Ono
Entropy , 2013, DOI: 10.3390/e15104300
Abstract: Ab initio molecular dynamics simulations were performed to investigate the elasticity of cubic CaSiO 3 perovskite at high pressure and temperature. All three independent elastic constants for cubic CaSiO 3 perovskite, C 11, C 12, and C 44, were calculated from the computation of stress generated by small strains. The elastic constants were used to estimate the moduli and seismic wave velocities at the high pressure and high temperature characteristic of the Earth’s interior. The dependence of temperature for sound wave velocities decreased as the pressure increased. There was little difference between the estimated compressional sound wave velocity ( VP) in cubic CaSiO 3 perovskite and that in the Earth’s mantle, determined by seismological data. By contrast, a significant difference between the estimated shear sound wave velocity ( VS) and that in the Earth’s mantle was confirmed. The elastic properties of cubic CaSiO 3 perovskite cannot explain the properties of the Earth’s lower mantle, indicating that the cubic CaSiO 3 perovskite phase is a minor mineral in the Earth’s lower mantle.
Hydrogen-bonds structure in poly(2-hydroxyethyl methacrylate) studied by temperature-dependent infrared spectroscopy
Shigeaki Morita
Frontiers in Chemistry , 2014, DOI: 10.3389/fchem.2014.00010
Abstract: Hydrogen-bonds structure in poly(2-hydroxyethyl methacrylate) (PHEMA) were investigated by means of temperature-dependent infrared (IR) spectroscopy. Spectral variations involved with the OH···OH and C=O···HO types of hydrogen-bonds were found around the glass transition temperature of 80°C. Hydrogen-bonds among the hydroxyl groups gradually dissociate with increasing temperature. In contrast, discontinuous variation in the carbonyl bands was observed around the glass transition temperature. An association of the C=O···HO type of hydrogen-bond with increasing temperature above the glass transition temperature was revealed. These were concluded from the present study that hydrogen-bonds among the hydroxyl groups in each side chain terminal suppress the main chain mobility in the polymer matrix below the glass transition temperature, while the dissociation of the OH···OH type of hydrogen-bonds induces the association of the C=O···HO type of hydrogen-bond. As a result, the mobility of the main chain is induced by the change in hydrogen-bonds structure at the glass transition temperature.
Information Metric on Instanton Moduli Spaces in Nonlinear Sigma Models
Shigeaki Yahikozawa
Physics , 2003, DOI: 10.1103/PhysRevE.69.026122
Abstract: We study the information metric on instanton moduli spaces in two-dimensional nonlinear sigma models. In the CP^1 model, the information metric on the moduli space of one instanton with the topological charge Q=k which is any positive integer is a three-dimensional hyperbolic metric, which corresponds to Euclidean anti--de Sitter space-time metric in three dimensions, and the overall scale factor of the information metric is (4k^2)/3; this means that the sectional curvature is -3/(4k^2). We also calculate the information metric in the CP^2 model.
Links and submersions to the plane on an open 3-manifold
Shigeaki Miyoshi
Mathematics , 2013,
Abstract: We study the realization problem which asks if a given oriented link in an open 3-manifold can be realized as a fiber of a submersion to the Euclidean plane. We correct the results obtained before by the author which contains an error and certain imperfection, and investigate a necessary and sufficient condition for the realization in the words of well-known invariants. We obtain the condition expressed by the first homology group with mod 2 coefficient.
On the Smooth Renyi Entropy and Variable-Length Source Coding Allowing Errors
Shigeaki Kuzuoka
Mathematics , 2015,
Abstract: In this paper, we consider the problem of variable-length source coding allowing errors. The exponential moment of the codeword length is analyzed in the non-asymptotic regime and in the asymptotic regime. Our results show that the smooth Renyi entropy characterizes the optimal exponential moment of the codeword length.
Prevention of type 2 diabetes in a primary healthcare setting: Three-year results of lifestyle intervention in Japanese subjects with impaired glucose tolerance
Naoki Sakane, Juichi Sato, Kazuyo Tsushita, Satoru Tsujii, Kazuhiko Kotani, Kokoro Tsuzaki, Makoto Tominaga, Shoji Kawazu, Yuzo Sato, Takeshi Usui, Isao Kamae, Toshihide Yoshida, Yutaka Kiyohara, Shigeaki Sato, Hideshi Kuzuya, Japan Diabetes Prevention Program (JDPP) Research Group the for
BMC Public Health , 2011, DOI: 10.1186/1471-2458-11-40
Abstract: Through health checkups in communities and workplaces, 304 middle-aged IGT subjects with a mean body mass index (BMI) of 24.5 kg/m2 were recruited and randomized to the intervention group or control group. The lifestyle intervention was carried out for 3 years by public health nurses using the curriculum and educational materials provided by the study group.After 1 year, the intervention had significantly improved body weight (-1.5 ± 0.7 vs. -0.7 ± 2.5 kg in the control; p = 0.023) and daily non-exercise leisure time energy expenditure (25 ± 113 vs. -3 ± 98 kcal; p = 0.045). Insulin sensitivity assessed by the Matsuda index was improved by the intervention during the 3 years. The 3-year cumulative incidence tended to be lower in the intervention group (14.8% vs.8.2%, log-rank test: p = 0.097). In a sub-analysis for the subjects with a BMI > 22.5 kg/m2, a significant reduction in the cumulative incidence was found (p = 0.027).The present lifestyle intervention program using existing healthcare resources is beneficial in preventing diabetes in Japanese with IGT. This has important implications for primary healthcare-based diabetes prevention.UMIN000003136The incidence of type 2 diabetes is increasing in Japan [1]. Although Japanese have a lower prevalence of obesity than Westerners, a tendency to gain weight due to lifestyle changes coupled with an aging of the population seems to be closely related to the rapid expansion of the diabetic population [1]. There is thus an urgent need for effective public health strategies to combat this situation in Japan.There is now substantial evidence that the development of type 2 diabetes can be prevented or delayed in high-risk subjects through lifestyle intervention [2-8]. The Finnish Diabetes Prevention Study (DPS) [4] and the US Diabetes Prevention Program (DPP) [5] have clearly shown that, in obese subjects with impaired glucose tolerance (IGT), lifestyle changes associated with a 5-7% decrease in body weight resulted in a 58
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