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Search Results: 1 - 10 of 349298 matches for " C. E. Tateyama "
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Structure of the inner jet of OJ 287 VLBA data at 15 GHz in a super-resolution mode
Claudio E. Tateyama
Physics , 2013, DOI: 10.1088/0067-0049/205/2/15
Abstract: In this work we show the results obtained from the VLBA data at 15 GHz of OJ 287 in the super-resolution mode. The data showed a jet configuration in the form of "fork" where superluminal components emerge via stationary components at the northwest and the southeast close to the core to form parallel trajectories along the southwest direction in the plane of the sky. This agrees with a source structure of an extended, broad morphology of OJ 287.
Observations of OJ 287 from the Geodetic VLBI Archive of the Washington Correlator
C. E. Tateyama,K. A. Kingham,P. Kaufmann,B. G. Piner,L. C. L. Botti,A. M. P. de Lucena
Physics , 1999, DOI: 10.1086/307475
Abstract: We present 27 geodetic VLBI maps of OJ 287 obtained from the archive of the Washington correlator. The observations presented here were made between 1990 October and 1996 December. During this period a sequence of six superluminal components has been identified. We measured the proper motion of these components to be approximately 0.5 mas/yr, which is about twice as high as that seen in previous VLBI observations. These results imply a higher component ejection rate than previously observed, in good agreement with the observed occurrences of radio outbursts. We have examined a possible connection between VLBI components and optical flares in the framework of a binary black hole system.
Real-time Background Subtraction for Video Avatar
Hasup Lee,Yoshisuke Tateyama,Tetsuro Ogi
International Journal of Future Computer and Communication , 2013, DOI: 10.7763/ijfcc.2013.v2.117
Abstract: Background subtraction is widely used method ofdetecting moving objects in static background in computervision fields. In this paper, we present real-time backgroundsubtraction method for video avatar system or videoconferencing without blue screen. We observed the noise ofdigital camera and made a range matrix for backgroundmasking. Noise reductions were applied to both backgroundand mask using median filter blurring and open operation. Ourexperiment was performed using notebook PC and built-inwebcam. The results showed our approach is feasible toreal-time indoor environments.
Learning an Intermittent Control Strategy for Postural Balancing Using an EMG-Based Human-Computer Interface
Yoshiyuki Asai, Shota Tateyama, Taishin Nomura
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0062956
Abstract: It has been considered that the brain stabilizes unstable body dynamics by regulating co-activation levels of antagonist muscles. Here we critically reexamined this established theory of impedance control in a postural balancing task using a novel EMG-based human-computer interface, in which subjects were asked to balance a virtual inverted pendulum using visual feedback information on the pendulum's position. The pendulum was actuated by a pair of antagonist joint torques determined in real-time by activations of the corresponding pair of antagonist ankle muscles of subjects standing upright. This motor-task raises a frustrated environment; a large feedback time delay in the sensorimotor loop, as a source of instability, might favor adopting the non-reactive, preprogrammed impedance control, but the ankle muscles are relatively hard to co-activate, which hinders subjects from adopting the impedance control. This study aimed at discovering how experimental subjects resolved this frustrated environment through motor learning. One third of subjects adapted to the balancing task in a way of the impedance-like control. It was remarkable, however, that the majority of subjects did not adopt the impedance control. Instead, they acquired a smart and energetically efficient strategy, in which two muscles were inactivated simultaneously at a sequence of optimal timings, leading to intermittent appearance of periods of time during which the pendulum was not actively actuated. Characterizations of muscle inactivations and the pendulum??s sway showed that the strategy adopted by those subjects was a type of intermittent control that utilizes a stable manifold of saddle-type unstable upright equilibrium that appeared in the state space of the pendulum when the active actuation was turned off.
Atmospheric gamma-ray observation with the BETS detectorfor calibrating atmospheric neutrino flux calculations
K. Kasahara,E. Mochizuki,S. Torii,T. Tamura,N. Tateyama,K. Yoshida,T. Yamagami,Y. Saito,J. Nishimura,H. Murakami,T. Kobayashi,Y. Komori,M. Honda,T. Ohuchi,S. Midorikawa,T. Yuda
Physics , 2002, DOI: 10.1103/PhysRevD.66.052004
Abstract: We observed atmospheric gamma-rays around 10 GeV at balloon altitudes (15~25 km) and at a mountain (2770 m a.s.l). The observed results were compared with Monte Carlo calculations to find that an interaction model (Lund Fritiof1.6) used in an old neutrino flux calculation was not good enough for describing the observed values. In stead, we found that two other nuclear interaction models, Lund Fritiof7.02 and dpmjet3.03, gave much better agreement with the observations. Our data will serve for examining nuclear interaction models and for deriving a reliable absolute atmospheric neutrino flux in the GeV region.
Gd-EOB-DTPA-enhanced magnetic resonance imaging features of hepatic hemangioma compared with enhanced computed tomography
Akihiro Tateyama,Yoshihiko Fukukura,Koji Takumi,Toshikazu Shindo
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i43.6269
Abstract: AIM: To clarify features of hepatic hemangiomas on gadolinium-ethoxybenzyl-diethylenetriaminpentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) compared with enhanced computed tomography (CT). METHODS: Twenty-six patients with 61 hepatic hemangiomas who underwent both Gd-EOB-DTPA-enhanced MRI and enhanced CT were retrospectively reviewed. Hemangioma appearances (presence of peripheral nodular enhancement, central nodular enhancement, diffuse homogenous enhancement, and arterioportal shunt during the arterial phase, fill-in enhancement during the portal venous phase, and prolonged enhancement during the equilibrium phase) on Gd-EOB-DTPA-enhanced MRI and enhanced CT were evaluated. The degree of contrast enhancement at the enhancing portion within the hemangioma was visually assessed using a five-point scale during each phase. For quantitative analysis, the tumor-muscle signal intensity ratio (SIR), the liver-muscle SIR, and the attenuation value of the tumor and liver parenchyma were calculated. The McNemar test and the Wilcoxon’s signed rank test were used to assess the significance of differences in the appearances of hemangiomas and in the visual grade of tumor contrast enhancement between Gd-EOB-DTPA-enhanced MRI and enhanced CT. RESULTS: There was no significant difference between Gd-EOB-DTPA-enhanced MRI and enhanced CT in the presence of peripheral nodular enhancement (85% vs 82%), central nodular enhancement (3% vs 3%), diffuse enhancement (11% vs 16%), or arterioportal shunt (23% vs 34%) during arterial phase, or fill-in enhancement (79% vs 80%) during portal venous phase. Prolonged enhancement during equilibrium phase was observed less frequently on Gd-EOB-DTPA-enhanced MRI than on enhanced CT (52% vs 100%, P < 0.001). On visual inspection, there was significantly less contrast enhancement of the enhancing portion on Gd-EOB-DTPA-enhanced MRI than on enhanced CT during the arterial (3.94 ± 0.98 vs 4.57 ± 0.64, respectively, P < 0.001), portal venous (3.72 ± 0.82 vs 4.36 ± 0.53, respectively, P < 0.001), and equilibrium phases (2.01 ± 0.95 vs 4.04 ± 0.51, respectively, P < 0.001). In the quantitative analysis, the tumor-muscle SIR and the liver-muscle SIR observed with Gd-EOB-DTPA-enhanced MRI were 0.80 ± 0.24 and 1.28 ± 0.33 precontrast, 1.92 ± 0.58 and 1.57 ± 0.55 during the arterial phase, 1.87 ± 0.44 and 1.73 ± 0.39 during the portal venous phase, 1.63 ± 0.41 and 1.78 ± 0.39 during the equilibrium phase, and 1.10 ± 0.43 and 1.92 ± 0.50 during the hepatobiliary phase, respectively. The attenuation values in the tumor and li
Temperature Dependent Polarity Reversal in Au/Nb:SrTiO3 Schottky Junctions
T. Susaki,Y. Kozuka,Y. Tateyama,H. Y. Hwang
Physics , 2007, DOI: 10.1103/PhysRevB.76.155110
Abstract: We have observed temperature-dependent reversal of the rectifying polarity in Au/Nb:SrTiO3 Schottky junctions. By simulating current-voltage characteristics we have found that the permittivity of SrTiO3 near the interface exhibits temperature dependence opposite to that observed in the bulk, significantly reducing the barrier width. At low temperature, tunneling current dominates the junction transport due both to such barrier narrowing and to suppressed thermal excitations. The present results demonstrate that novel junction properties can be induced by the interface permittivity.
First-principles molecular dynamics simulations of proton diffusion in cubic BaZrO3 perovskite under strain conditions
Marco Fronzi,Yoshitaka Tateyama,Nicola Marzari,Enrico Traversa
Physics , 2013,
Abstract: First-principles molecular dynamics simulations have been employed to analyze the proton diffusion in cubic BaZrO3 perovskite at 1300K, and a non-linear effect of an applied isometric strain of 2% on the lattice parameter has been observed. The structural and electronic properties of BaZrO3 are analyzed, based on Density Functional Theory calculations, and after an analysis of the electronic structure, we provide a possible explanation for an enhanced ionic conductivity, that can be caused by the formation of a preferential path for proton diffusion under compressive strain conditions.
Role of Conduction Electrons in the ortho-KC$_{60}$ Polymer
T. Ogitsu,K. Kusakabe,S. Tsuneyuki,Y. Tateyama
Physics , 1997,
Abstract: We present first-principles band calculations as well as structural optimization of the orthorhombic K$_1$C$_{60}$ polymerized phase. We found three-dimensional inter-fullerene bonding/anti-bonding characters consisting of $t_{1u}$ molecular orbitals with $p$-like symmetry in the conduction bands. The formation of the four-membered ring connecting the fullerenes lifts the $p_x$ band from the continuous $p_y$-$p_z$ band, where the z-axis is parallel to the chain. The asymmetry between $p_x$ and $p_y$ may play an important role in binding the chains with the rotational configuration proposed by Stephens et al.
Caregiving, Family Burden and Medication Adherence  [PDF]
E. Ennis, C. Corry
Open Journal of Medical Psychology (OJMP) , 2014, DOI: 10.4236/ojmp.2014.31009
Abstract: Caregivers are an essential component of any community. Advances in medicalcare have brought about an increasing population which is reliant on care, and communities deal with most of the burdens and practicalities of public health issues. In order to provide efficient support services, we need to know the challenges of caregivers so that we can address what types of support they require. The current study examines whether those who have a mental health difficulty and are either engaged in caregiving duties or perceive family burden may be less adherent to their medications in comparison with those who also have a mental health difficulty but do not perceive family burden or perform caregiving. Data used was from the National Comorbidity Study Replication (NCS-R), which examines the mental health profile of the American population. The group examined were those who received the family burden interview, and indicated that they were taking a prescription medication for a mental health difficulty under the supervision of a health professional (N = 489). Zero inflated Poisson regression showed that caregiving/family burden was unrelated to adherence to supervised prescription medicines for mental health difficulties, regardless of the kinship of who was ill, or the nature of their illness (physical versus mental). Adherence to prescription medications for mental health difficulties does not appear to be one of the challenges faced by this group. Findings are discussed in terms of the economic and moral importance of health professionals identifying and understanding the challenges experienced by caregivers/those reporting family burden. This is necessary so that appropriate interventions and support services can be targeted, and further research plays an important role in achieving this objective.
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