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Search Results: 1 - 10 of 326343 matches for " S Yamaguchi "
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Inverse Compton Scattering Model for X-ray Emission of the Gamma-ray Binary LS 5039
Masaki S. Yamaguchi,Fumio Takahara
Physics , 2012, DOI: 10.1088/0004-637X/761/2/146
Abstract: We propose a model for the gamma-ray binary LS 5039 in which the X-ray emission is due to the inverse Compton (IC) process instead of the synchrotron radiation. Although the synchrotron model has been discussed in previous studies, it requires a strong magnetic field which leads to a severe suppression of the TeV gamma-ray flux in conflict with H.E.S.S. observations. In this paper, we calculate the IC emission by low energy electrons (\gamma_e \lesssim 10^3) in the Thomson regime. We find that IC emission of the low energy electrons can explain the X-ray flux and spectrum observed with Suzaku if the minimum Lorentz factor of injected electrons \gamma_min is around 10^3. In addition, we show that the Suzaku light curve is well reproduced if \gamma_min varies in proportion to the Fermi flux when the distribution function of injected electrons at higher energies is fixed. We conclude that the emission from LS 5039 is well explained by the model with the IC emission from electrons whose injection properties are dependent on the orbital phase. Since the X-ray flux is primarily determined by the total number of cooling electrons, this conclusion is rather robust, although some mismatches between the model and observations at the GeV band remain in the present formulation.
The Acquisition of Complex Structures: The Case of Child ESL  [PDF]
Yumiko Yamaguchi
Open Journal of Modern Linguistics (OJML) , 2013, DOI: 10.4236/ojml.2013.33030
Abstract:

This study examines how complex linguistic structures are acquired in child English as a second language. The spontaneous speech producing by a Japanese primary school child, learning English in a naturalistic environment, was audio-recorded regularly over two years and the development of complex syntactic structures containing subordinate clauses was compared with the acquisition of other English morphosyntactic structures as represented within Processability Theory (PT) (Pienemann, 1998; Pienemann, Di Biase, & Kawaguchi, 2005). Although PT predicts that subordination is acquired at the highest stage in processability hierarchy, the results in this longitudinal study show that some of the subordinate constructions emerge at earlier stages in child ESL acquisition.

Effect of lift force on the aerodynamics of dust grains in the protoplanetary disk
Masaki S. Yamaguchi,Shigeo S. Kimura
Physics , 2014, DOI: 10.1186/1880-5981-66-132
Abstract: We newly introduce lift force into the aerodynamics of dust grains in the protoplanetary disk. Although many authors have so far investigated the effects of the drag force, gravitational force and electric force on the dust grains, the lift force has never been considered as a force exerted on the dust grains in the gas disk. If the grains are spinning and moving in the fluid, then the lift force is exerted on them. We show in this paper that the dust grains can be continuously spinning due to the frequent collisions so that the lift force continues to be exerted on them, which is valid in a certain parameter space where the grain size is larger than ~ 1 m and where the distance from the central star is larger than 1 AU for the minimum mass solar nebula. In addition, we estimate the effects of the force on the grain motion and obtain the result that the mean relative velocity between the grains due to the lift force is comparable to the gas velocity in the Kepler rotational frame when the Stokes number and lift-drag ratio are both ~ 1. This estimation is performed under the assumptions of the steady state and the isotropic spin angular momentum. We also estimate the mean relative velocity when the grains keep spinning and conclude that the lift force marginally affects the mean relative velocity in the minimum mass solar nebula. If there is a grain-concentrated part in the disk, the relative velocity due to the lift force may dominate there because of high collision rate.
Morphostasis in a novel eukaryote illuminates the evolutionary transition from phagotrophy to phototrophy: description of Rapaza viridis n. gen. et sp. (Euglenozoa, Euglenida)
Aika Yamaguchi, Naoji Yubuki, Brian S Leander
BMC Evolutionary Biology , 2012, DOI: 10.1186/1471-2148-12-29
Abstract: We cultivated a novel marine euglenid, Rapaza viridis n. gen. et sp. ("green grasper"), and a green alga, Tetraselmis sp., from the same environment. Cells of R. viridis were comprehensively characterized with light microscopy, SEM, TEM, and molecular phylogenetic analysis of small subunit rDNA sequences. Ultrastructural and behavioral observations demonstrated that this isolate habitually consumes a specific strain of Tetraselmis prey cells and possesses a functional chloroplast that is homologous with other phototrophic euglenids. A novel feeding apparatus consisting of a reduced rod of microtubules facilitated this first and only example of mixotrophy among euglenids. R. viridis also possessed a robust photoreception apparatus, two flagella of unequal length, euglenoid movement, and a pellicle consisting of 16 strips and one (square-shaped) whorl of posterior strip reduction. The molecular phylogenetic data demonstrated that R. viridis branches as the nearest sister lineage to phototrophic euglenids.The unusual combination of features in R. viridis combined with its molecular phylogenetic position completely conforms to the expected transitional stage that occurred during the early evolution of phototrophic euglenids from phagotrophic ancestors. The marine mixotrophic mode of nutrition, the preference for green algal prey cells, the structure of the feeding apparatus, and the organization of the pellicle are outstanding examples of morphostasis that clarify pivotal stages in the evolutionary history of this diverse group of microbial eukaryotes.The reconstruction of early stages in the evolution of complex characters requires awareness of different degrees of morphostasis in character states as reflected in the unity and diversity of organisms. Evolutionary biologists who study groups of organisms with rich fossil records (e.g., molluscs, vertebrates, diatoms and foraminiferans) have the luxury of comparing both extinct and extant species to infer patterns of cha
Movement of intraretinal fluid from distant branch retinal vein occlusion to the submacular space
Otani T, Yamaguchi Y, Kishi S
Clinical Ophthalmology , 2013, DOI: http://dx.doi.org/10.2147/OPTH.S40198
Abstract: vement of intraretinal fluid from distant branch retinal vein occlusion to the submacular space Case Series (697) Total Article Views Authors: Otani T, Yamaguchi Y, Kishi S Published Date January 2013 Volume 2013:7 Pages 81 - 86 DOI: http://dx.doi.org/10.2147/OPTH.S40198 Received: 11 November 2012 Accepted: 13 December 2012 Published: 09 January 2013 Tomohiro Otani, Yumiko Yamaguchi, Shoji Kishi Department of Ophthalmology, Gunma University School of Medicine, Maebashi, Gunma, Japan Background: Extramacular branch retinal vein occlusion (BRVO) occasionally causes serous macular detachment. We studied the movement of extravasated fluid from BRVO lesions to the submacular space. Methods: We examined nine eyes from nine patients with serous retinal detachment caused by extramacular BRVO. In addition to a comprehensive ophthalmic examination, optical coherence tomography was performed in all nine eyes. Six of the patients also underwent fluorescein angiography. Results: Visual acuity ranged from 0.03 to 0.9 (median 0.5). All nine eyes showed localized macular detachment and retinal edema which extended from the extramacular BRVO to the macula. Fluorescein angiography revealed dye leakage in the extramacular area but no macular leakage in the six eyes examined. Optical coherence tomography revealed serous retinal detachment in the macula and intraretinal swelling, with low reflectivity in the outer retina extending from the distant BRVO toward the detached macula in all nine eyes. Six eyes were treated with laser photocoagulation, covering the entire area of BRVO, and the other three eyes were treated with intravitreal bevacizumab. Serous retinal detachment and retinal swelling resolved within 3 months of treatment in all nine eyes. Conclusion: Distant retinal vascular leakage appears to diffuse through the outer retina to the macula, then permeate into the subretinal space.
Movement of intraretinal fluid from distant branch retinal vein occlusion to the submacular space
Otani T,Yamaguchi Y,Kishi S
Clinical Ophthalmology , 2013,
Abstract: Tomohiro Otani, Yumiko Yamaguchi, Shoji KishiDepartment of Ophthalmology, Gunma University School of Medicine, Maebashi, Gunma, JapanBackground: Extramacular branch retinal vein occlusion (BRVO) occasionally causes serous macular detachment. We studied the movement of extravasated fluid from BRVO lesions to the submacular space.Methods: We examined nine eyes from nine patients with serous retinal detachment caused by extramacular BRVO. In addition to a comprehensive ophthalmic examination, optical coherence tomography was performed in all nine eyes. Six of the patients also underwent fluorescein angiography.Results: Visual acuity ranged from 0.03 to 0.9 (median 0.5). All nine eyes showed localized macular detachment and retinal edema which extended from the extramacular BRVO to the macula. Fluorescein angiography revealed dye leakage in the extramacular area but no macular leakage in the six eyes examined. Optical coherence tomography revealed serous retinal detachment in the macula and intraretinal swelling, with low reflectivity in the outer retina extending from the distant BRVO toward the detached macula in all nine eyes. Six eyes were treated with laser photocoagulation, covering the entire area of BRVO, and the other three eyes were treated with intravitreal bevacizumab. Serous retinal detachment and retinal swelling resolved within 3 months of treatment in all nine eyes.Conclusion: Distant retinal vascular leakage appears to diffuse through the outer retina to the macula, then permeate into the subretinal space.Keywords: branch retinal vein occlusion, optical coherence tomography, serous macular detachment, fluorescein angiography, outer retina
AdS_3/CFT_2 Correspondence and Space-Time N=3 Superconformal Algebra
S. Yamaguchi,Y. Ishimoto,K. Sugiyama
Physics , 1999, DOI: 10.1088/1126-6708/1999/02/026
Abstract: We study a Wess-Zumino-Witten model with target space AdS_3 x (S^3 x S^3 x S^1)/Z_2. This allows us to construct space-time N=3 superconformal theories. By combining left-, and right-moving parts through a GSO and a Z_2 projections, a new asymmetric (N,\bar{N})=(3,1) model is obtained. It has an extra gauge (affine) SU(2) symmetry in the target space of the type IIA string. An associated configuration is realized as slantwise intersecting M5-M2 branes with a Z_2-fixed plane in the M-theory viewpoint.
Variation formulas for principal functions (II) Applications to variation for harmonic spans
S. Hamano,F. Maitani,H. Yamaguchi
Mathematics , 2010,
Abstract: For a domain $D$ in $\mathbb{C}_z$ with smooth boundary and for $a,b\in D, a\ne b$, we have the circular (radial) slit mapping $P(z)(Q(z))$ on $D$ such that $P(z)- \frac{1}{z-a}\ (Q(z)- \frac{1}{z-a})$ is regular at $a$ and $P(b)(Q(b))=0$, and we call $p(z)=\log |P(z)|\ (q(z)=\log|Q(z)|)$ the $L_1$-($L_0$-)principal function; \ $\alpha =\log|P'(b)|$ $(\beta =\log|Q'(b)|)$ the $L_1$-($L_0$-)constant, and \ $s=\alpha - \beta $ the harmonic span, for $D$. S.\,Hamano in \cite{hamano-2} showed the variation formula of the second order for the $L_1$-const. $\alpha (t)$ for the moving domain $D(t)$ in $\mathbb{C}_z$ with $t \in B:=\{t\in \mathbb{C}: |t|<\rho\}$. We show the corresponding formula for the $L_0$-const. $\beta (t)$ for $D(t)$, and combine these formulas to obtain, if the total space ${\mathcal D}=\cup_{t\in B}(t, D(t)) $ is pseudoconvex in $ B \times \mathbb{C}_z$, then $s(t)$ is subharmonic on $B$. Since the geometric meaning of $s(t)$ is showed, this fact gives one of the relations between the conformal mappings on each fiber $D(t), t\in B$ and the pseudoconvexity of ${\mathcal D}$. As a simple application we obtain the subharmonicity of $\log \cosh d(t)$ on $B$, where $d(t)$ is the Poincar\'e distance between $a$ and $b$.
Simulation of Returning Electrons from a Klystron Collector
Z. Fang,S. Fukuda,S. Yamaguchi,S. Anami
Physics , 2000,
Abstract: Spurious oscillations in klystrons due to returning electrons from the collector into the drift tube were observed and studied at KEK. Simulations of returning electrons using EGS4 Monte Carlo method have been performed. And the oscillation conditions are described in this paper.
Earthquake fault rock indicating a coupled lubrication mechanism
S. Okamoto, G. Kimura, S. Takizawa,H. Yamaguchi
eEarth (eE) & Discussions (eED) , 2006, DOI: 10.5194/ee-1-23-2006
Abstract: A pseudotachylyte bounded by a carbonate-matrix implosion breccia was found at a fossilized out-of-sequence thrust in the Shimanto accretionary complex, Japan. This occurrence resulted from the following events: first implosion of host rock due to interstitial fluid pressure increase and asymmetric fracturing; second, Ca-Fe-Mg carbonate precipitation; and third, frictional melting. The rock-record suggests that these events took place in a single seismogenic slip event. Resulting from abrupt drop in fluid pressure after implosion, hydro-fracturing and fluid escape, recovered high effective friction promoted melting during fault movement. Coexistence of fluid implosion breccia and pseudotachylyte has never been reported from continental pseudotachylytes, but might be characteristic from hydrous seismogenic faults in subduction zones.
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