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Search Results: 1 - 10 of 152353 matches for " H. Watanabe "
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Leptospirosis vaccines: Past, present, and future
Koizumi N,Watanabe H
Journal of Postgraduate Medicine , 2005,
Abstract: It is well known that Leptospira vaccine prevents the disease. However specificity for serovars limits the efficacy of killed whole cell vaccines. Leptospiral antigens that induce cross-protective immunity to the various serovars are sought as new vaccine candidates. In this paper, we have summarized both past and current findings about leptospiral antigens that are conserved among pathogenic leptospires and that induce protective immunity in animal models. The full-length genome sequences of two Leptospira strains have been published and reverse vaccinology has been used to identify leptospiral vaccine candidates. Although humoral immunity is thought to be dominant in protection from leptospiral infection, a role for cell-mediated immunity is now being explored.
A dynamical mean-field theory approach to superconductivity and antiferromagnetism in a strongly correlated electron system
H. Watanabe,S. Doniach
Physics , 2002,
Abstract: We present the results of numerical studies of superconductivity and antiferromagnetism in a strongly correlated electron system. To do this we construct a Hubbard model on a lattice of self-consistently embedded multi-site clusters by means of a dynamical mean-field theory in which intra-cluster dynamics is treated essentially exactly. We show that a class of characteristic features which have been seen in the excitation spectra of high-$T_{c}$ cuprates (e.g., pseudogap and the spin-flip resonance), as well as their interplay with the onset of a pairing correlations, can be captured within a dynamical mean-field theory in which short-wavelength dynamics are rigorously treated. Thus we infer that the observation of the neutron scattering resonance in the superconducting state of the cuprate superconductors does not appear to be directly tied to their quasi-2D character. Although our approach is defined strictly in terms of fermion degrees of freedom, we show that we can readily identify the emergence of effective low energy bosonic degrees of freedom in the presence of a well-defined broken symmetry phase as long as their dynamics are dominated by short-range, short-wavelength fluctuations. Our results reveal that the dynamics of staggered spin degrees of freedom builds up coherence and a resonance-like sharp feature emerges as pairing correlations set in. Under conditions of superconducting broken symmetry our approach thus extends static BCS mean field theory to provide an exact treatment of quantum fluctuations of the BCS order parameter.
Contributions of GRBs and Cen A-like Radio Galaxies to the Cosmic Gamma-ray Background
K. Watanabe,D. H. Hartmann
Physics , 2001, DOI: 10.1063/1.1419445
Abstract: The contribution to the cosmic diffuse gamma-ray background (CGB) from Gamma Ray Bursts (GRBs) is studied in the 40 keV - 2 MeV regime. We use High Energy Resolution (HER) data from the Burst And Transient Source Experiment (BATSE) aboard the Compton Gamma-Ray Observatory (CGRO) to generate a GRB template spectrum. Although the GRB contribution to the CGB is generally small, in comparison to the dominant flux from Type Ia supernovae, the integrated GRB flux is in fact comparable to that from SNIa in the narrow 10-40 keV range. GRBs contribute to the CGB at the same level as Type II supernovae do. Although BATSE data are not available below ~40 keV, extrapolation of the template spectrum suggests that bursts can fill a significant part of the existing gap between Seyfert galaxies (dominating the CGB below ~ 100 keV) and SNIa (dominating at ~1 MeV). We estimate contributions from Cen A-like (FR I) radio galaxies in this energy regime, where INTEGRAL data is expected to provide major advances.
Manipulation of the Dirac cones and the anomaly in the graphene related quantum Hall effect
H Watanabe,Y Hatsugai,H Aoki
Physics , 2010, DOI: 10.1088/1742-6596/334/1/012044
Abstract: The quantum Hall effect in graphene is regarded to be involving half-integer topological numbers associated with the massless Dirac particle, this is usually not apparent due to the doubling of the Dirac cones. Here we theoretically consider two classes of lattice models in which we manipulate the Dirac cones with either (a) two Dirac points that have mutually different energies, or (b) multiple Dirac cones having different Fermi velocities. We have shown, with an explicit calculation of the topological (Chern) number for case (a) and with an adiabatic argument for case (b) that the results are consistent with the picture that a single Dirac fermion contributes the half-odd integer series (... -3/2, -1/2, 1/2, 3/2, ...) to the Hall conductivity when the Fermi energy traverses the Landau levels.
Effects of collisions on conservation laws in gyrokinetic field theory
H. Sugama,T. -H. Watanabe,M. Nunami
Physics , 2015, DOI: 10.1063/1.4928378
Abstract: Effects of collisions on conservation laws for toroidal plasmas are investigated based on the gyrokinetic field theory. Associating the collisional system with a corresponding collisionless system at a given time such that the two systems have the same distribution functions and electromagnetic fields instantaneously, it is shown how the collisionless conservation laws derived from Noether's theorem are modified by the collision term. Effects of the external source term added into the gyrokinetic equation can be formulated similarly with the collisional effects. Particle, energy, and toroidal momentum balance equations including collisional and turbulent transport fluxes are systematically derived using a novel gyrokinetic collision operator, by which the collisional change rates of energy and canonical toroidal angular momentum per unit volume in the gyrocenter space can be given in the conservative forms. The ensemble-averaged transport equations of particles, energy, and toroidal momentum given in the present work are shown to include classical, neoclassical, and turbulent transport fluxes which agree with those derived from conventional recursive formulations.
Effects of water flow volume on the isolation of bacteria from motion sensor faucets  [PDF]
Y. Nakamura, M. Watanabe, E. Kubo, A. Suzuki, H. Igari, M. Kitada, T. Sato
Health (Health) , 2011, DOI: 10.4236/health.2011.33027
Abstract: Water outlets for washing hands and medical equipment are essential for preventing hospital infection. The present study clarified the effects of water flow volume on the identification and quantitative evaluation of bacteria found around spouts in the 17 hand-washing stations. Pseu-domonas aeruginosa was detected from 4 sta-tions before adjustment and 2 after adjustment. Although no significant difference was identified in the detection rate of P. aeruginosa (p = 0.368), when combining P. aeruginosa and glucose non-fermentative Gram-negative bacilli (NFB), the number of stations with P. aeruginosa and/or NFB decreased significantly from 15 before adjustment to 9 after adjustment (p = 0.023). Before adjust-ment, quantity of bacteria was “2+” for 3 stations and “1+” for 7 stations, but was “1+” for 3 stations and “2+” for 0 stations after adjustment. These results show that quantity of bacteria could be reduced from spouts by adjusting flow volume. These results were also supported by experiments for cleanliness using Adenosine 5’-triphosphate bioluminescence me- thod.
5-Aminolevulinic Acid (5-ALA): Analysis of Preclinical and Safety Literature  [PDF]
Michael H. Perez, Beatriz L. Rodriguez, Terry T. Shintani, Keitaro Watanabe, Setsuko Miyanari, Rosanne C. Harrigan
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.410131

Problem: 5-ALA has been used for many years at relatively high dose amounts in single doses for photodynamic therapy and immunofluorescence of tumors. An analysis of compiled data relating to safety and any side-effects about the use of 5-ALA at low doses has not yet been published. Purpose: This report analyzes data about the safety of the use of 5-Aminolevulinic Acid (5-ALA) in low doses as a supplement over an extended period of time. Methods: This investigation is a systematic analysis of the current literature ((Medline, and SBI) and snowballing techniques) related to the safety and efficacy of 5-ALA in animals and humans. Clinical trials in progress using 5-ALA were also analyzed. Constant comparative analyses were used to synthesize the findings. Results: The safety of low-dose 5-ALA as a supplement has been demonstrated by animal and human studies. The results suggest that none of the investigations document the presence of symptoms or abnormal laboratory results of clinical significance. The minor laboratory changes documented were judged not clinically significant.

Hierarchical Stochastic Simulation Algorithm for SBML Models of Genetic Circuits
Leandro H. Watanabe,Chris J. Myers
Frontiers in Bioengineering and Biotechnology , 2014, DOI: 10.3389/fbioe.2014.00055
Abstract: This paper describes a hierarchical stochastic simulation algorithm, which has been implemented within iBioSim, a tool used to model, analyze, and visualize genetic circuits. Many biological analysis tools flatten out hierarchy before simulation, but there are many disadvantages associated with this approach. First, the memory required to represent the model can quickly expand in the process. Second, the flattening process is computationally expensive. Finally, when modeling a dynamic cellular population within iBioSim, inlining the hierarchy of the model is inefficient since models must grow dynamically over time. This paper discusses a new approach to handle hierarchy on the fly to make the tool faster and more memory-efficient. This approach yields significant performance improvements as compared to the former flat analysis method.
59Co-NMR Knight Shift of Superconducting Three-Layer NaxCoO2.yH2O
H. Watanabe,Y. Kobayashi,M. Sato
Physics , 2005, DOI: 10.1143/JPSJ.74.2563
Abstract: The superconducting state of NaxCoO2.yH2O with three CoO2 layers in a unit cell has been studied by 59Co-NMR. The Knight shift measured for a peak of the NMR spectra corresponding to the external magnetic field H along one of the principal directions within the CoO2 plane, exhibits a rapid decrease with decreasing temperature T below the superconducting transition temperature Tc, indicating that the spin susceptibility is suppressed in the superconducting phase, at least, for this field direction. Because differences of the superconducting properties are rather small between this three-layer NaxCoO2.yH2O and previously reported NaxCoO2.yH2O with two CoO2 layers within a unit cell, the present result of the Knight shift studies indicates that the Cooper pairs of the former system are in the singlet state as in the latter, for which the spin susceptibility is suppressed for both directions of H parallel and perpendicular to the CoO2 plane.
Nuclear Magnetometry Study of Spin Dynamics in Bilayer Quantum Hall Systems
M. H. Fauzi,S. Watanabe,Y. Hirayama
Physics , 2014, DOI: 10.1103/PhysRevB.90.235308
Abstract: We performed a nuclear magnetometry study on quantum Hall ferromagnet with a bilayer total filling factor of $\nu_{\rm{tot}} = 2$. We found not only a rapid nuclear relaxation but also a sudden change in the nuclear spin polarization distribution after a one-second interaction with a canted antiferromagnetic phase. We discuss the possibility of observing cooperative phenomena coming from nuclear spin ensemble triggered by electrons with collective spin interactions.
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