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Search Results: 1 - 10 of 2577 matches for " Fumio Kato "
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Surveillance of Fluoroquinolone-Resistant Clinical Isolates of Pseudomonas aeruginosa  [PDF]
Hideki Kobayashi, Miho Isozaki, Tatsuya Fukuda, Yojiro Anzai, Fumio Kato
Open Journal of Medical Microbiology (OJMM) , 2013, DOI: 10.4236/ojmm.2013.32022
Abstract: Ciprofloxacin (CPFX) and pazufloxacin (PZFX) have strong antibacterial activity against Pseudomonas aeruginosa. We investigated the sensitivity of P. aeruginosa to CPFX and PZFX in 373 strains isolated from inpatients (321 strains) and outpatients (52 strains) during September 2010 to September 2011 at Toho University Ohashi Medical Center. The percentage of CPFX-non-susceptible (≥3.91 μg/mL) among inpatients was 22.4%, but that among outpatients was 1.9%. As the major resistance mechanism to fluoroquinolones in P. aeruginosa involves modification of type II topoisomerases (DNA gyrase and topoisomerase IV), we examined mutations in the quinolone-resistance-determining regions (QRDRs) of gyrA and parC of P. aeruginosa isolates. Among the 373 isolates, 73 isolates had reduced CPFX-susceptibility and 88 had reduced PZFX-susceptibility. Sequencing of gyrA and parC revealed base substitutions that resulted in amino acid replacements in QRDR of GyrA in 70 P. aeruginosa isolates, while Thr83Ile (in GyrA) and Ser87Leu (in ParC) substitutions were found in 12 strains. These replacements were clearly associated with reduced susceptibility to CPFX and PZFX. However, we also found strains with high MICs to quinolones without mutations in either gyrA or parC. We then investigated the effect of efflux pumps in CPFX-resistance in these isolates. In the presence of an efflux pump inhibitor, MIC values in 12 of 66 strains decreased to 1/23. We also sequenced genes related to overexpression of efflux pumps, viz., mexZ, mexR, and nfxB. Eight of the strains without mutations in QRDRs had a mutation in mexZ, 7 strains had a mutation in mexR, but no mutation was identified in nfxB.
Probabilistic description of the first-order Fermi acceleration in shock waves: Time-dependent solution by single-particle approach
Tsunehiko N. Kato,Fumio Takahara
Physics , 2003, DOI: 10.1046/j.1365-8711.2003.06583.x
Abstract: We give a new coherent description of the first-order Fermi acceleration of particles in shock waves from the point of view of stochastic process of the individual particles, under the test particle approximation. The time development of the particle distribution function can be dealt with by this description, especially for relativistic shocks. We formulate the acceleration process of a particle as a two-dimensional Markov process in a logarithmic momentum-time space, and relate the solution of the Markov process with the particle distribution function at the shock front, for both steady and time-dependent case. For the case where the probability density function of the energy gain and cycle-time at each shock crossing of the particles obeys a scaling law in momentum, which is usually assumed in the literature, it is confirmed in more general form that the energy distribution of particles has the power-law feature in steady state. The equation to determine the exact power-law index which is applicable for any shock speed is derived and it is shown that the power-law index, in general, depends on the shape of the probability density function of the energy gain at each shock crossing; in particular for relativistic shocks, the dispersion of the energy gain can influence the power-law index. It is also shown that the time-dependent solution has a self-similarity for the same case.
Piericidins, Novel Quorum-Sensing Inhibitors against Chromobacterium violaceum CV026, from Streptomyces sp. TOHO-Y209 and TOHO-O348  [PDF]
Kazuhiro Ooka, Atsushi Fukumoto, Tomoe Yamanaka, Kanako Shimada, Ryo Ishihara, Yojiro Anzai, Fumio Kato
Open Journal of Medicinal Chemistry (OJMC) , 2013, DOI: 10.4236/ojmc.2013.34012
Abstract: Piericidin A1, 3’-rhamnopiericidin A1, and a novel compound piericidin E, a new quorum-sensing (QS) inhibitor
against Chromobacterium violaceum CV026, were isolated from the culture broth of Streptomyces sp. QS is well
known as a microbial signaling system and controls certain types of gene expression resulting in bioluminescence,
biofilm formation, swarming motility, antibiotic biosynthesis, and virulence factor production. C. violaceum CV026 is
commonly used to determine qualitative and quantitative QS activity. The structures of piericidin derivatives were characterized,
and their QS activities were determined.
Global Structure and Dynamics of Advection-Dominated Accretion Flows Around Black Holes
Ramesh Narayan,Shoji Kato,Fumio Honma
Physics , 1996, DOI: 10.1086/303591
Abstract: We present global solutions that describe advection-dominated accretion flows around black holes. The solutions are obtained by numerically solving a set of coupled ordinary differential equations corresponding to a steady axisymmetric height-integrated flow. The solutions satisfy consistent boundary conditions at both ends. We obtain well-behaved transonic solutions for a wide range of values of the viscosity parameter $\alpha$, from 0.001 to 0.3. We do not find any need for shocks in our solutions, and disagree with previous claims that viscous accretion flows with low values of $\alpha$ must have shocks. We see a qualitative difference between solutions with low values of the viscosity parameter, $\alpha\ \sles\ 0.01$, and those with large values, $\alpha\sgreat\ 0.01$. The solutions with low $\alpha$ have their sonic transitions occurring close to the radius of the marginally bound orbit. These flows are characterized by regions of super-Keplerian rotation, and have pressure maxima outside the sonic point. The solutions are similar in many respects to the hydrostatic thick tori developed previously as models of active galactic nuclei. In contrast, the solutions with large $\alpha$ have sonic transitions farther out, close to or beyond the marginally stable orbit, and have no super-Keplerian rotation or pressure maxima. We believe these flows will be nearly quasi-spherical down to the sonic radius and will not have empty funnels along the rotation axis. The large $\alpha$ solutions are more likely to be representative of real systems.
The Electron Spectrum in 3C279 and the Observed Emission Spectrum
Masaaki Kusunose,Fumio Takahara,Tomohiro Kato
Physics , 2003, DOI: 10.1086/377330
Abstract: The emission mechanisms of the blazar 3C 279 are studied by solving the kinetic equations of electrons and photons in a relativistically moving blob. The gamma-ray spectral energy distribution (SED) is fitted by inverse Compton scattering of external photons. The bulk Lorentz factor of the emitting blob is found to be 25, and the magnetic field is found to be 0.3 G. GeV gamma-rays are well explained by inefficiently cooled electrons because of the Klein-Nishina effects. The electron spectrum is not a broken power law with a steeper spectrum above a break energy, which is often used to fit the observed SED. The kinetic energy density of the nonthermal electrons dominates the magnetic energy density; this result is qualitatively the same as that for TeV blazars such as Mrk 421 and Mrk 501. The gamma-ray luminosity of 3C 279 is often observed to increase rapidly. We show that one of the better sampled gamma-ray flares can be explain by the internal shock model.
Optimisation of Cultural Conditions and Some Properties of Radical Scavenging Substance from Sporobolomyces salmonicolor
Masudur Rahman Gazi,Kohzo Kanda,Masaaki Yasuda,Fumio Kato
Pakistan Journal of Biological Sciences , 2004,
Abstract: Sporobolomyces salmonicolor produced high activity (101 u mL-1) in the stationary culture while cultivated in the half YPD (H-YPD) medium. This activity production was maximised while optimising cultural condition. The effects of nutrients including several carbon and nitrogen sources were assayed along with medium pH and cultivation temperature. The optimised medium consisted of 0.5% yeast extract, 1% polypepton and 1% fructose. A maximum radical scavenging activity (176 u mL-1 ) was obtained when cells were cultivated with this medium in the stationary condition for 9 days at 25 C with an initial pH of 6.0. This was 1.7-fold increase of initial production from H-YPD. The active substances were partially purified by means of ion exchange chromatography and gel filtration. Two active substances were isolated from gel filtration, namely, DG I and DG II. The molecular mass of DG I is expected to be high. The activity was stable between pH 6.0-7.0 and until 60 C for 30 min incubation. On the contrary, the molecular mass of the DG II was estimated to be 281 m/z. This substance was stable in the acidic condition (pH 4.0-6.0) and almost 90% of the initial activity was lost above pH 8.0. Its activity remained stable at 100 C for 60 min. The spectrometric analysis shows that this substance might have aromatic structure.
An Empirical Study of Contrasting IoT with IT: Evidences of Differences Drawn from Japanese Experiences  [PDF]
Fumio Kodama
American Journal of Industrial and Business Management (AJIBM) , 2018, DOI: 10.4236/ajibm.2018.81003
Abstract: By contrasting IoT (Internet of Things) with IT (Information Technology), various evidences of the difference between them are discovered by our empirical and case studies. For empirical evidence, a comparison is made between the personal computer as representing a case of IT and the automobiles as representing a case of the future IoT, since the self-driving of cars is discussed quite frequently nowadays. Based on their patenting behavior, the degree of modularization is measured, and effects of digitalization on modularization are found out to differ between PC and automobile industries. Similar modularity analysis is employed to sub-module suppliers, and they are found out to be integrative rather than modularly structured, because analogue technologies are essential at the level of sub-module supplying. Through our modularity analyses, it becomes clear that a digitalization brings about a modularization, and will eventually bring an IoT evolution. In order to illustrate the evolutionary process from digitalization to internetworking via modularization, we will investigate a chronology of the machine tool development in Japan ever since 1975. In order to illustrate the evolutionary process of becoming interconnected, we will make a study on a construction machinery manufacturer, i.e. how a manufacturer can go downstream into a service innovation. These case studies will show clearly that the process of upgrading of ITs into an IoT evolution is incremental by its nature and is additive in its essence, i.e. the value is added
The Relation among the Solar Activity, the Total Ozone, QBO, NAO, and ENSO by Wavelet-Based Multifractal Analysis  [PDF]
Fumio Maruyama
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.66109
Abstract: There is an increasing interest in the relation between the solar activity and climate change. As for the solar activity, a fractal property of the sunspot number was studied by many works. In general, a fractal property was observed in the time series of dynamics of complex systems. The purposes of this study are to investigate the relations among the solar activity, total ozone, Quasi-Biennial Oscillation (QBO), the North Atlantic Oscillation (NAO), and El Ni?o-Southern Oscillation (ENSO) from a view of multi-fractality. To detect the changes of multifractality, we examined the multifractal analysis on the time series of the solar 10.7-cm radio flux (F10.7 flux), total ozone, QBO, NAO, and Ni?o3.4 indices. During the period 1950 and 2010, for the F10.7 flux and QBO index, the matching in monofractality or multifractality is observed and the increase and decrease of multifractality is similar; that is the change of multifractality is similar. In the same way, it is very similar, during the period 1985 and 2010, for the QBO and the total ozone, and during the period 1950 and 2010, for the QBO, and NAO and for the QBO, and Ni?o3.4. Compared to Ni?o3.4, the multifractality of NAO and QBO was strong and it turns out that they are undergoing unstable change.
Relationship between the Atmospheric CO2 and Climate Indices by Wavelet-Based Multifractal Analysis  [PDF]
Fumio Maruyama
Journal of Geoscience and Environment Protection (GEP) , 2019, DOI: 10.4236/gep.2019.71004
Abstract: Atmospheric concentrations of greenhouse gases are rising, leading to a positive radiative forcing of climate and an expected warming of surface temperatures. In general, fractal properties may be observed in the time series of the dynamics of complex systems. To study the relation between the atmospheric CO2 concentration and the climate indices, we investigated the change of fractal behavior of the CO2, the carbon isotope ratio (δ13C) of atmospheric CO2, the El Ni?o-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO) indices using the multifractal analysis. When the atmospheric CO2 growth rate was large, the multifractality of CO2, δ13C in CO2, ENSO, and NAO was large and the changes were large from the change of fractality. The changes of CO2 and ENSO were closely related and the influence of the CO2 on the ENSO was strong from the change in fractality and wavelet coherence. When the El Ni?o occurred, the CO2 growth rate was large. The CO2 related to PDO, NAO, and global temperature from the change in fractality and wavelet coherence. Especially, the changes of CO2 and global temperature were closely related. When the global warming hiatus occurred, the multifractality of the global temperature was weaker than that of CO2 and the change of the global temperature was stable. These findings will contribute to the research of the relation between the atmospheric CO2 and climate change.
Relationship between the Sunspot Number and Solar Polar Field by Wavelet-Based Multifractal Analysis  [PDF]
Fumio Maruyama
Journal of Applied Mathematics and Physics (JAMP) , 2019, DOI: 10.4236/jamp.2019.75070
There is increasing interest in finding the relation between the sunspot number (SSN) and solar polar field. In general, fractal properties may be observed in the time series of the dynamics of complex systems, such as solar activity and climate. This study investigated the relations between the SSN and solar polar field by performing a multifractal analysis. To investigate the change in multifractality, we applied a wavelet transform to time series. When the SSN was maximum and minimum, the SSN showed monofractality or weak multifractality. The solar polar field showed weak multifractality when that was maximum and minimum. When the SSN became maximum, the fractality of the SSN changed from multifractality to monofractality. The multifractality of SSN became large before two years of SSN maximum, then that of the solar polar field became large and changed largely. It was found that the change in SSN triggered the change in the solar polar field. Hence, the SSN and solar polar field were closely correlated from the view point of fractals. When the maximum solar polar field before the maximum SSN was larger, the maximum SSN of the next cycle was larger. The formation of the magnetic field of the sunspots was correlated with the solar polar field.
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