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Search Results: 1 - 10 of 402376 matches for " M. Sakai "
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Comment on Ambiguities in the Holographic Weyl Anomaly
M. Fukuma,T. Sakai
Physics , 2000, DOI: 10.1142/S0217732300002164
Abstract: We consider possible ambiguities in the holographic Weyl anomaly that are caused by local terms in the flow equation. We point out that such ambiguities actually do not give physically meaningful contributions to the Weyl anomaly.
Asymmetric Electrostatic Force  [PDF]
Katsuo Sakai
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2014, DOI: 10.4236/jemaa.2014.610026
Abstract: Asymmetric electrostatic forces are a very interesting and new phenomenon. The magnitude of an electrostatic force that acts on a point charge does not change when the direction of the electric field is reversed. On the contrary, the magnitude of the electrostatic force that acts on a charged asymmetric shaped conductor does change when the direction of the electric field is reversed. 5 years ago, this phenomenon was reported by a simple experiment and a simulation and named as an Asymmetric electrostatic force unofficially by the author. After that, several simulations confirmed this phenomenon. However, several experiments did not yet confirm it clearly. The difference between the simulations and the experiments depends upon differences of their conditions. The simulations had been done under ideal (perfect) conditions; the experiments, on the contrary, had been done under actual (not perfect) conditions. In the new experiment, its conditions were improved to near ideal (perfect) conditions. As a result the existence of the Asymmetric electrostatic force was more clearly confirmed.
Surface Properties of Cement Paste Evaluated by Scanning Probe Microscopy  [PDF]
Yuya Sakai
Open Journal of Civil Engineering (OJCE) , 2016, DOI: 10.4236/ojce.2016.64052
Abstract: The microscopic physical properties of Hardened Cement Paste (HCP) surfaces were evaluated by using Scanning Probe Microscopy (SPM). The cement pastes were cured under a hydrostatic pressure of 400 MPa and the contacting surfaces with a slide glass during the curing were studied. Scanning Electron Microscope (SEM) observation at a magnification of 7000 revealed smooth surfaces with no holes. The surface roughness calculated from the SPM measurement was 4 nm. The surface potential and the frictional force measured by SPM were uniform throughout the measured area 24 h after the curing. However, spots of low surface potential and stains of low frictional force and low viscoelasticity were observed one month after curing. This change was attributed to the carbonation of hydrates.
A Study of Weighted Polynomial Approximations with Several Variables (II)  [PDF]
Ryozi Sakai
Applied Mathematics (AM) , 2017, DOI: 10.4236/am.2017.89093
Abstract: In this paper we investigate weighted polynomial approximations with several variables. Our study relates to the approximation for \"\" by weighted polynomial. Then we will give some results relating to the Lagrange interpolation, the best approximation, the Markov-Bernstein inequality and the Nikolskii- type inequality.
A Study of Weighted Polynomial Approximations with Several Variables (I)  [PDF]
Ryozi Sakai
Applied Mathematics (AM) , 2017, DOI: 10.4236/am.2017.89095
Abstract: In this paper, we investigate the weighted polynomial approximations with several variables. Our study relates to the approximation for \"\" by weighted polynomials. Then we will estimate the degree of approximation.
Sakai M.C.,Hiss H.
Brazilian Journal of Chemical Engineering , 1997,
Abstract: The influence of the surface-active agent Tween 80 (polyoxyethylene 20 sorbitan monoleate) on the dispersed growth of Mycobacterium bovis - BCG - was studied. The slopes of the bacterial dry mass / absorbance curves, were significantly reduced, by the increase of the Tween 80 concentration in the medium. Such an influence was probably due to the effect Tween 80 had on the average size of bacterial clumps during the culture carried out in a bench fermenter
Unified Analysis of Spin Isospin Responses of Nuclei
T. Wakasa,M. Ichimura,H. Sakai
Physics , 2004, DOI: 10.1103/PhysRevC.72.067303
Abstract: We investigated the Gamow-Teller (GT) strength distribution, especially the quenching with respect to the GT sum rule, and the enhancement of the pionic responses in the quasielasic scattering region, in the same theoretical framework. That is the continuum random phase approximation with the pi+rho+g' model interaction, incorporated with distorted wave impulse approximation and two-step calculations. From this analysis we searched the Landau-Migdal parameters, g'NN and g'ND, through the comparison with the experimental data of the GT strength distribution obtained at 300 MeV and the spin-longitudinal (pionic) cross sections IDq of (p,n) at 350 and 500 MeV. This comprehensive and sophisticated study gave a common set of g'NN=0.6-0.7 and g'ND=0.2-0.4, for both low and high momentum transfers.
Exact Analysis of ESR Shift in the Spin-1/2 Heisenberg Antiferromagnetic Chain
Y. Maeda,K. Sakai,M. Oshikawa
Physics , 2005, DOI: 10.1103/PhysRevLett.95.037602
Abstract: A systematic perturbation theory is developed for the ESR shift and is applied to the spin-1/2 Heisenberg chain. Using the Bethe ansatz technique, we exactly analyze the resonance shift in the first order of perturbative expansion with respect to an anisotropic exchange interaction. Exact result for the whole range of temperature and magnetic field, as well as asymptotic behavior in the low-temperature limit are presented. The obtained g-shift strongly depends on magnetic fields at low temperature, showing a significant deviation from the previous classical result.
CH radio emission from heiles cloud 2 as a tracer of molecular cloud evolution
N. Sakai,H. Maezawa,T. Sakai,K. M. Menten,S. Yamamoto
Physics , 2012, DOI: 10.1051/0004-6361/201219106
Abstract: A mapping observation of the $J=1/2$ $\Lambda$-type doubling transition (3.3 GHz) of CH has been conducted toward Heiles Cloud 2 (HCL2) in the Taurus molecular cloud complex to reveal its molecular cloud-scale distribution. The observations were carried out with the Effelsberg 100 m telescope. The CH emission is found to be extended over the whole region of HCL2. It is brighter in the southeastern part, which encloses the TMC-1 cyanopolyyne peak than in the northwestern part. Its distribution extends continuously from the peak of the neutral carbon emission (CI peak) to the TMC-1 ridge, as if it were connecting the distributions of the [C I] and C$^{18}$O emissions. Since CH is an intermediate in gas-phase chemical reactions from C to CO, its emission should trace the transition region. The above distribution of the CH emission is consistent with this chemical behavior. Since the CH abundance is subject to the chemical evolutionary effect, the CH column density in HCL2 no longer follows a linear correlation wit the H$_2$ column density reported for diffuse and translucent clouds. More importantly, the CH line profile is found to be composed of the narrow and broad components. Although the broad component is dominant around the CI peak, the narrow component appears in the TMC-1 ridge and dense core regions such as L1527 and TMC-1A. This trend seems to reflect a narrowing of the line width during the formation of dense cores. These results suggest that the 3.3 GHz CH line is a useful tool for tracing the chemical and physical evolution of molecular clouds.
A Third-Order Scheme for Numerical Fluxes to Guarantee Non-Negative Coefficients for Advection-Diffusion Equations  [PDF]
Katsuhiro Sakai, Daishi Watabe
American Journal of Computational Mathematics (AJCM) , 2011, DOI: 10.4236/ajcm.2011.11004
Abstract: According to Godunov theorem for numerical calculations of advection equations, there exist no high-er-order schemes with constant positive difference coefficients in a family of polynomial schemes with an accuracy exceeding the first-order. In case of advection-diffusion equations, so far there have been not found stable schemes with positive difference coefficients in a family of numerical schemes exceeding the second-order accuracy. We propose a third-order computational scheme for numerical fluxes to guarantee the non-negative difference coefficients of resulting finite difference equations for advection-diffusion equations. The present scheme is optimized so as to minimize truncation errors for the numerical fluxes while fulfilling the positivity condition of the difference coefficients which are variable depending on the local Courant number and diffusion number. The feature of the present optimized scheme consists in keeping the third-order accuracy anywhere without any numerical flux limiter by using the same stencil number as convemtional third-order shemes such as KAWAMURA and UTOPIA schemes. We extend the present method into multi-dimensional equations. Numerical experiments for linear and nonlinear advection-diffusion equations were performed and the present scheme’s applicability to nonlinear Burger’s equation was confirmed.
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