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Search Results: 1 - 10 of 50960 matches for " Y. Ishihara "
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IL-1 Receptor Type II Production Is Upregulated by IL-4 and IL-13, and Downregulated by IFN-γ in Mouse Gingival Epithelial Cells  [PDF]
Y. Kamiya, Y. Ishihara, H. Kamei, Y. Ozawa, H. Mizutani, K. Kubo, H. Maeda, T. Noguchi
Modern Research in Inflammation (MRI) , 2014, DOI: 10.4236/mri.2014.32005
Abstract:

Background and Objective: Interleukin-1 (IL-1) binds to 2 distinct and separate receptors, types I and II (IL-1RI and IL-1RII, respectively). The binding of IL-1 to IL-1RI induces cellular signaling and biological effects, whereas binding to IL-1RII does not induce cellular signaling and indirectly inhibits IL-1 biological activities such as that of the decoy receptor. Recently, Suzukiet al.reported that soluble IL-1RII (sIL-1RII) was detected in gingival crevicular fluid from a periodontitis patient. However, it remains unclear which cells produce sIL-1RII detected in periodontal tissues. We examined the localization of IL-1RII producing cells in gingival tissues as well as related production control mechanisms. Material and Methods: IL-1RII mRNA expression in gingival epithelial cells (GE1) was performed by real-time PCR analysis, while the amount of sIL-1RII production in supernatant from GE1 cells was examined by dot-blot analysis. Involvement of the phosphorylation of STAT6 in the signaling pathway was determined by western blot analysis. Statistical analysis was performed with Student’st-test. Results: Culturing with IL-4 and IL-13 significantly increased IL-1RII mRNA to levels 10.5-and 8.89-fold, respectively, above that of the control (p< 0.01), while addition of interferon-γ (IFN-γ) significantly suppressed IL-1RII mRNA by 0.22-fold as compared to the control (p< 0.05). Soluble IL-1RII in the supernatant of cultured GE1 cells was increased by IL-4 and IL-13, and decreased by IFN-γ, while western blotting determines the suppression of IL-1RII production by IFN-γ. Without the addition of IL-4 or IL-13 with or without

Comments on Closed Bianchi Models
Y. Fujiwara,H. Ishihara,H. Kodama
Physics , 1993, DOI: 10.1088/0264-9381/10/5/006
Abstract: We show several kinematical properties that are intrinsic to the Bianchi models with compact spatial sections. Especially, with spacelike hypersurfaces being closed, (A) no anisotropic expansion is allowed for Bianchi type V and VII(A\not=0), and (B) type IV and VI(A\not=0,1) does not exist. In order to show them, we put into geometric terms what is meant by spatial homogeneity and employ a mathematical result on 3-manifolds. We make clear the relation between the Bianchi type symmetry of space-time and spatial compactness, some part of which seem to be unnoticed in the literature. Especially, it is shown under what conditions class B Bianchi models do not possess compact spatial sections. Finally we briefly describe how this study is useful in investigating global dynamics in (3+1)-dimensional gravity.
Numerical Study of Photo-Induced Dynamics in Double-Exchange Model
Y. Kanamori,H. Matsueda,S. Ishihara
Physics , 2010, DOI: 10.1103/PhysRevB.82.115101
Abstract: Photo-induced spin and charge dynamics in double-exchange model are numerically studied. The Lanczos method and the density-matrix renormalization-group method are applied to one-dimensional finite-size clusters. By photon irradiation in a charge ordered (CO) insulator associated with antiferromagnetic (AFM) correlation, both the CO and AFM correlations collapse rapidly, and appearances of new peaks inside of an insulating gap are observed in the optical spectra and the one-particle excitation spectra. Time evolutions of the spin correlation and the in-gap state are correlated with each other, and are governed by the transfer integral of conduction electrons. Results are interpreted by the charge kink/anti-kink picture and their effective motions which depend on the localized spin correlation. Pump-photon density dependence of spin and charge dynamics are also studied. Roles of spin degree of freedom are remarkable in a case of weak photon density. Implications of the numerical results for the pump-probe experiments in perovskite manganites are discussed.
Dynamical coupling and separation of multiple degrees of freedom in a photoexcited double-exchange system
Y. Kanamori,H. Matsueda,S. Ishihara
Physics , 2009, DOI: 10.1103/PhysRevLett.103.267401
Abstract: We present a theory of ultrafast photo-induced dynamics in a spin-charge coupled system, motivated by pump-probe experiments in perovskite manganites. A microscopic picture for multiple dynamics in spin and charge degrees is focused on. Real-time simulations are carried out by two complimentary methods. Our calculation demonstrates that electron motion governs a short-time scale where charge and spin dynamics are combined strongly, while, in a long-time scale controlled by spin relaxation, charge sector does not follow remarkable change in spin sector. Present results are in contrast to a conventional double-exchange picture in equilibrium states.
Photo-induced spin-state change in itinerant correlated-electron system
Y. Kanamori,H. Matsueda,S. Ishihara
Physics , 2011, DOI: 10.1103/PhysRevLett.107.167403
Abstract: Photo-induced spin-state change in itinerant correlated-electron system is studied. The model Hamiltonians before and after photon-pumping are derived from the two-orbital Hubbard model with crystalline field splitting. A photon introduced in the low-spin band insulator induces a bound state of the high-spin state and a photoexcited hole. This bound state brings a characteristic peak in the optical absorption spectra in the photo-excited state. The resent results well explain the recent experimental results of the ultrafast optical spectroscopy in perovskite cobaltites.
Effects of Improving Public Services for Tourism Developments in Islands: The Case of Remote Islands in Nagasaki, Japan  [PDF]
Tadahiro Okuyama, Hayato Ishihara
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.36018
Abstract: Growths of numbers of tourists who stay long-term in tourism sites are an important policy for local governments in islands due to their locations that are far from urban areas. However, many tourists hesitate to stay long-term in islands owing to not only the expensive travel costs but also the lack of public services in islands. The purpose of this study is to examine effects of improving public services in islands for tourists’ willingness to pays (WTPs) and non-tourists’ attitudes for long-term stays. Data on tourism activity for islands, Nagasaki, Japan were used. Respondents were asked about their WTPs for long-term stays and their needs for public services of islands; reductions of costs for rent or purchasing houses for long-term stays and travel costs, easy to take a vacation, to enhance medical services, educational services and job search services. The logit model was used for estimations. Median and mean values of WTPs (per year) were calculated JPY 151,629 (USD 1184) and JPY 242,110 (USD 3008). Positive effects on five public services (without travel costs) were confirmed. For example, the median values of WTPs were increased to JPY 478,369 (USD 5943) when the medical services were improved, and JPY 1,484,704 (USD 18,446) when all public services were improved. The results showed that improvement of public services have the effect 1) to improve tourists’ benefits and 2) to change many non-tourists’ attitudes from the rejection of staying long term in islands to the acceptance. Thus, results indicate that it would be better for central and/or local governments in islands to enhance islands’ public services.
Spin dynamical properties and orbital states of the layered perovskite La_2-2x_Sr_1+2x_Mn_2_O_7 (0.3 <= x < 0.5)
K. Hirota,S. Ishihara,H. Fujioka,M. Kubota,H. Yoshizawa,Y. Moritomo,Y. Endoh,S. Maekawa
Physics , 2001, DOI: 10.1103/PhysRevB.65.064414
Abstract: Low-temperature spin dynamics of the double-layered perovskite La_2-2x_Sr_1+2x_Mn_2_O_7 (LSMO327) was systematically studied in a wide hole concentration range (0.3 <= x < 0.5). The spin-wave dispersion, which is almost perfectly 2D, has two branches due to a coupling between layers within a double-layer. Each branch exhibits a characteristic intensity oscillation along the out-of-plane direction. We found that the in-plane spin stiffness constant and the gap between the two branches strongly depend on x. By fitting to calculated dispersion relations and cross sections assuming Heisenberg models, we have obtained the in-plane (J_para), intra-bilayer (J_perp) and inter-bilayer (J') exchange interactions at each x. At x=0.30, J_para=-4meV and J_perp=-5meV, namely almost isotropic and ferromagnetic. Upon increasing x, J_perp rapidly approaches zero while |J_para| increases slightly, indicating an enhancement of the planar magnetic anisotropy. At x=0.48, J_para reaches -9meV, while J_perp turns to +1meV indicating an antiferromagnetic interaction. Such a drastic change of the exchange interactions can be ascribed to the change of the relative stability of the d_x^2-y^2 and d_3z^2-r^2 orbital states upon doping. However, a simple linear combination of the two states results in an orbital state with an orthorhombic symmetry, which is inconsistent with the tetragonal symmetry of the crystal structure. We thus propose that an ``orbital liquid'' state realizes in LSMO327, where the charge distribution symmetry is kept tetragonal around each Mn site.
Observation of the antiferroquadrupolar order in DyB2C2 by resonant x-ray scattering
T. Matsumura,N. Oumi,K. Hirota,H. Nakao,Y. Murakami,Y. Wakabayashi,T. Arima,S. Ishihara,Y. Endoh
Physics , 2000, DOI: 10.1103/PhysRevB.65.094420
Abstract: We have investigated the antiferroquadrupolar(AFQ) order in DyB$_2$C$_2$ by resonant x-ray scattering. X-rays with energies near the $L_3$ absorption edge of Dy were employed. Superlattice peaks that correspond to three kinds of propagation vectors of (1 0 0), (1 0 1/2) and (0 0 1/2) were investigated in detail with polarization analyses. The experimental results are analyzed using a formalism on resonant x-ray scattering and a model of the AFQ order. The magnetic and quadrupolar scatterings are explained by the model satisfactorily. A detailed investigation on the critical behavior of the AFQ ordering is also reported. The critical exponent $\beta$ is deduced to be 0.35, not far from the three-dimensional Heisenberg system. We have also succeeded in detecting the diffuse scattering above $T_{Q}$.
Temporal Prediction of Aircraft Loss-of-Control: A Dynamic Optimization Approach  [PDF]
Chaitanya Poolla, Abraham K. Ishihara
Intelligent Control and Automation (ICA) , 2015, DOI: 10.4236/ica.2015.64023
Abstract: Loss of Control (LOC) is the primary factor responsible for the majority of fatal air accidents during past decade. LOC is characterized by the pilot’s inability to control the aircraft and is typically associated with unpredictable behavior, potentially leading to loss of the aircraft and life. In this work, the minimum time dynamic optimization problem to LOC is treated using Pontryagin’s Maximum Principle (PMP). The resulting two point boundary value problem is solved using stochastic shooting point methods via a differential evolution scheme (DE). The minimum time until LOC metric is computed for corresponding spatial control limits. Simulations are performed using a linearized longitudinal aircraft model to illustrate the concept.
Underactuated manipulator robot control via H2, H∞, H2/H∞, and μ-synthesis approaches: a comparative study
Siqueira, Adriano A. G.;Terra, Marco H.;Ishihara, Jo?o Y.;Barbeiro, Tácio L. S.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2009, DOI: 10.1590/S1678-58782009000400001
Abstract: abstract this paper deals with robust control of underactuated manipulator robots. it presents a comparative study of four combined controllers h2, h∞ , h2/h∞ and μ-synthesis, pluscomputed torque method. these controllers are applied in an actual underactuated manipulator robot with 3 degrees of freedom, of which joints can be configured as active or passive ones. the study performed in this paper compares the robustness of each controller when different disturbances are considered.
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