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Search Results: 1 - 10 of 1055 matches for " Hikaru Ogawa "
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The Relationship between Privatization and Regulation on Foreign Investment Policies  [PDF]
Lihua Han, Hikaru Ogawa
Theoretical Economics Letters (TEL) , 2015, DOI: 10.4236/tel.2015.51014
Abstract: Using a simple mixed oligopoly model, this paper examines the relationship between market-openings to foreign capital and privatization of a domestic public firm. Two types of market-openings are considered. First is that, given the number of the firms, the restriction on the share of foreign capital in each corporate joint venture is relaxed. Second is that, given the share of foreign capital in each corporate joint venture, the restriction on the number of the firms is relaxed. The analysis shows that the optimal level of privatization critically depends on the types of market openings to foreign capital. The optimal level of privatization declines as the share of foreign capital in each corporate joint venture increases. By contrast, the optimal level of privatization rises with an increase in the number of the firms operating in the market. The two different strategies for market-openings result in the opposite impacts on the welfare-maximizing government’s incentive for privatization.
Myocardial Segmentation of Area at Risk Based on Coronary Computed Tomography Angiography and Voronoi Diagram in Comparison with Magnetic Resonance Perfusion Imaging  [PDF]
Naoki Fukuyama, Teruhito Kido, Akira Kurata, Yuki Tanabe, Tomoyuki Kido, Takahiro Yokoi, Ryo Ogawa, Hikaru Nishiyama, Teruyoshi Uetani, Teruhito Mochizuki
Open Journal of Radiology (OJRad) , 2017, DOI: 10.4236/ojrad.2017.71002
Abstract: Purpose: To assess the clinical feasibility of automated segmentation of the myocardial area at risk (MAAR) using coronary computed tomography angiography (CT-MAAR), as compared to stress magnetic resonance myocardial perfusion imaging (MR-MPI). Materials and Methods: Thirty patients who underwent coronary computed tomography angiography (CTA) and stress MR-MPI were retrospectively evaluated. The myocardial territory of the left ventricle (LV) distal to coronary artery stenosis (≥50% or ≥70% stenosis on coronary CTA) was three-dimensionally quantified using a Voronoi diagram. The ratio of all stenosis-related territories to the LV volume was defined as CT-MAAR (%-LV volume). The proportion of segments with perfusion defects in stress MR-MPI to the total of 16 segments (range: 0% - 100%; with a 6.3%-interval scale) was defined as the reference. Correlation was assessed using Spearman’s test. The capability of CT-MAAR to predict the ischemic burden was assessed. Results: Stress MR-MPI depicted a median ischemic burden of 25.2% (range: 18.9% - 44.1%) in 30 patients without myocardial infarction. When CTA stenosis criteria of ≥50% (n = 30) and ≥70% (n = 27) were applied to estimate CT-MAAR, the median CT-MAAR values were 48.2% (31.6% - 64.3%) and 32.5% (23.7% - 51.9%), respectively. The correlations between the CT-MAAR values and the MR-based ischemic burden were significant (0.73 and 0.97 for ≥50% and ≥70% stenosis, respectively). CT-MAAR predicted the MR-based ischemic burden within ±1 segment of %-LV (6.3%) in 40% (12/30) of patients with ≥50% stenosis, and in 81.5% (22/27) of patients with ≥70% stenosis. Conclusions: Comprehensive assessment of resting coronary CTA combined with Voronoi diagram-based myocardial segmentation may help predict the myocardial ischemic burden in patients with severe coronary CTA stenosis.
Carbon Dioxide Capture and Utilization for Gas Engine  [PDF]
Takashi Ogawa
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.510064

Sodium glycinate absorption and ethylene carbonate synthesis from a mixture gas of ethylene oxide and carbon dioxide are evaluated as carbon dioxide capture and utilization system for gas engine flue gas. The energy requirement for CO2 capture is estimated at 3.3 GJ/tonne CO2. The ethylene carbonate synthesis utilizes more than 90% of the captured CO2 and supply 2.5 GJ/tonne CO2 of thermal energy, which is 76% of the energy requirement for CO2 capture. The thermal integration of the sodium glycinate absorption and the ethylene carbonate synthesis reduces the energy requirement for CO2 capture from 3.3 GJ/tonne CO2 to 0.8 GJ/tonne CO2. The energy requirement for the CO2 capture is supplied using the steam saturated at 0.78 MPa from the gas engine without its electric power reduction.

Chirality scenario of the spin-glass ordering
Hikaru Kawamura
Physics , 2009, DOI: 10.1143/JPSJ.79.011007
Abstract: Detailed account is given of the chirality scenario of experimental spin-glass transitions. In this scenario, the spin glass order of weakly anisotropic Heisenberg-like spin-glass magnets including canonical spin glasses are essentially chirality driven. Recent numerical and experimental results are discussed in conjunction with this scenario.
Two models of spin glasses -- Ising versus Heisenberg
Hikaru Kawamura
Physics , 2010, DOI: 10.1088/1742-6596/233/1/012012
Abstract: Brief review is given on recent numerical research of the ordering of two typical models of spin glasses (SGs), the three-dimensional (3D) Ising SG and the 3D Heisenberg SG models. Particular attention is paid to the questions of whether there is a thermodynamic transition in zero field, what are the associated critical properties, what is the nature of the ordered state, particularly of a possible replica-symmetry breaking, and whether there is a thermodynamic transition in applied fields. The properties of the two models are contrasted, and possible relation to experiments is discussed.
Nature of the vortex-glass order in strongly type-II superconductors
Hikaru Kawamura
Physics , 2003, DOI: 10.1103/PhysRevB.68.220502
Abstract: The stability and the critical properties of the three-dimensional vortex-glass order in random type-II superconductors with point disorder is investigated in the unscreened limit based on a lattice {\it XY} model with a uniform field. By performing equilibrium Monte Carlo simulations for the system with periodic boundary conditions, the existence of a stable vortex-glass order is established in the unscreened limit. Estimated critical exponents are compared with those of the gauge-glass model.
Fluctuation-dissipation ratio of the Heisenberg spin glass
Hikaru Kawamura
Physics , 2002, DOI: 10.1103/PhysRevLett.90.237201
Abstract: Fluctuation-dissipation (FD) relation of the three-dimensional Heisenberg spin glass with weak random anisotropy is studied by off-equilibrium Monte Carlo simulation. Numerically determined FD ratio exhibits a ``one-step-ike''behavior, the effective temperature of the spin-glass state being about twice the spin-glass transition temperature, $T_{{\rm eff}}\simeq 2T_g$, irrespective of the bath temperature. The results are discussed in conjunction with the recent experiment by Herisson and Ocio, and with the chirality scenario of spin-glass transition.
Z2-vortex order of frustrated Heisenberg antiferromagnets in two dimensions
Hikaru Kawamura
Physics , 2011, DOI: 10.1088/1742-6596/320/1/012002
Abstract: We discuss the recent experimental data on various frustrated quasi-two-dimensional Heisenberg antiferromagnets from the viewpoint of the Z2-vortex order, which include S=3/2 triangular-lattice antiferromagnet NaCrO2, S=1 triangular-lattice antiferromagnet NiGa2S4, S=1/2 organic triangular-lattice antiferromagnets \kappa-(BEDT-TTF)2Cu2(CN)3 and EtMe3Sb[Pd(dmit)2]2, and S=1/2 kagome-lattice antiferromagnet volborthite Cu3V2O7(OH)22H2O, etc.
The ordering of XY spin glasses
Hikaru Kawamura
Physics , 2011, DOI: 10.1088/0953-8984/23/16/164210
Abstract: Ordering properties of XY-like spin-glass magnets with an easy-plane magnetic anisotropy are studied based on a symmetry consideration and the results of recent numerical simulations on the pure Heisenberg and XY spin-glass models. The effects of an easy-plane-type uniaxial anisotropy, a random magnetic anisotropy and an applied magnetic field are investigated. In the XY regime in zero field, the "spin-chirality decoupling" persists even under the random magnetic anisotropy, escaping the "spin-chirality recoupling" phenomenon which inevitably occurs in the Heisenberg regime. Contrast between the scalar chiral order and the vector chiral order is emphasized. Implications to experiments are discussed.
Successive transitions and intermediate chiral phase in a superfuilid ^3He film
Hikaru Kawamura
Physics , 1998, DOI: 10.1103/PhysRevLett.82.964
Abstract: Superfluidity ordering of thin ^3He films is studied by Monte Carlo simulations based on a two-dimensional lattice spin model with Z_2\times U(1)\times SO(3) symmetry. Successive phase transitions with an intermediate `chiral' phase, in which the l-vector aligns keeping the phase of the condensate disordered, is found. Possible experiments to detect the successive transitions are discussed.
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