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Search Results: 1 - 10 of 4320 matches for " Hideki Yamamoto "
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Positioning Training Tool for Radiography  [PDF]
Toshinori Maruyama, Hideki Yamamoto
Positioning (POS) , 2013, DOI: 10.4236/pos.2013.44029
Abstract:

Accurate positioning reduces the X-ray exposure of the subject and produces a valuable X-ray image for diagnosis. This paper describes the development of a positioning training tool that supports those studying to be radiological technologists in learning the positioning technique efficiently. Students perform the positioning on a personal computer using a three-dimensional computer graphics (3DCG) phantom constructed from computed tomography (CT) image data and confirm the produced plane image corresponding to the positioned phantom. It is expected that students will be able to undertake positioning training using our tool anywhere and at any time without using X-ray equipment. Repeated use of our training tool will help students attain a deep understanding of anatomy and acquire positioning skills efficiently and accurately.

Performance of Thermal Energy Storage Unit Using Solid Ammoniated Salt (CaCl2-NH3 System)  [PDF]
Yuki Sakamoto, Hideki Yamamoto
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.58031
Abstract:
The exothermic chemical reaction of CaCl2 (calcium chloride) with NH3 (ammonia) can be utilized as an energy storage system. Since this reaction is a typical gas-solid reaction, the reaction rate is controlled by the heat transfer rate. In order to improve the low heat transfer rate of the ammoniation and the deammoniation of CaCl2, the influence of a heat transfer media (Ti: titanium) on the heat transfer rate of the solid ammoniated salt (CaCl2.mNH3) was studied and tested experimentally. The performance tests were carried out under the conditions of various weight ratios of Ti. No decrease of the activation of chemical reaction and no corrosion of experimental apparatus were observed on the repeated runs (≥30 times each). The heat transfer rate of ammoniated salt was greatly improved by adding Ti under the constant pressure (0.5 MPa). The reaction time required for the ammoniation of CaCl2 mixed with Ti was approximately 16% - 54% shorter than that of CaCl2 alone, and the reaction time required for the deammoniation was also approximately 19% - 59% shorter than that of CaCl2 alone.
Measurement of Thermophysical Property of Energy Storage System (CaCl2.NH3 System)  [PDF]
Yuki Sakamoto, Hideki Yamamoto
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.512060
Abstract: In order to measure the thermophysical properties of ammoniated salt (CaCl2.mNH3: m = 4, 8) as an energy storage system utilizing natural resources, the measurement unit was developed, and the thermophysical properties (effective thermal conductivity and thermal diffusivity) of CaCl2.mNH3 and CaCl2.mNH3 with heat transfer media (Ti: titanium) were measured by the any heating method. The effective thermal conductivities of CaCl2.4NH3 + Ti and CaCl2.8NH3 + Ti were 0.14 - 0.17 and 0.18 - 0.20 W/(m.K) in the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.5 - 2.2 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The effective thermal diffusivities were 0.22 - 0.24 × 10-6 and 0.18 - 0.19 × 10-6 m2/sin the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.3 - 1.5 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The obtained results show that the thermophysical properties have a dependence on the bulk densities and specific heats of CaCl2.mNH3 and
Implementation of Lees-Edwards periodic boundary conditions for direct numerical simulations of particle dispersions under shear flow
Hideki Kobayashi,Ryoichi Yamamoto
Physics , 2010, DOI: 10.1063/1.3537974
Abstract: A general methodology is presented to perform direct numerical simulations of particle dispersions in a shear flow with Lees-Edwards periodic boundary conditions. The Navier-Stokes equation is solved in oblique coordinates to resolve the incompatibility of the fluid motions with the sheared geometry, and the force coupling between colloidal particles and the host fluid is imposed by using a smoothed profile method. The validity of the method is carefully examined by comparing the present numerical results with experimental viscosity data for particle dispersions in a wide range of volume fractions and shear rates including nonlinear shear-thinning regimes.
Reentrant transition in the shear viscosity of dilute rigid rod dispersions
Hideki Kobayashi,Ryoichi Yamamoto
Physics , 2011, DOI: 10.1103/PhysRevE.84.051404
Abstract: The intrinsic viscosity of a dilute dispersion of rigid rods is studied using a recently developed direct numerical simulation (DNS) method for particle dispersions. A reentrant transition from shear-thinning to the 2nd Newtonian regime is successfully reproduced in the present DNS results around a Peclet number ${\rm Pe}=150$, which is in good agreement with our theoretical prediction of ${\rm Pe}=143$, at which the dynamical crossover from Brownian to non-Brownian behavior takes place in the rotational motion of the rotating rod. The viscosity undershoot is observed in our simulations before reaching the 2nd Newtonian regime. The physical mechanisms behind these behaviors are analyzed in detail.
Tumbling motion of a single chain in shear flow: a crossover from Brownian to non-Brownian behavior
Hideki Kobayashi,Ryoichi Yamamoto
Physics , 2009, DOI: 10.1103/PhysRevE.81.041807
Abstract: We present numerical results for the dynamics of a single chain in steady shear flow. The chain is represented by a bead-spring model, and the smoothed profile method is used to accurately account for the effects of thermal fluctuations and hydrodynamic interactions acting on beads due to host fluids. It is observed that the chain undergoes tumbling motions and that its dimensionless frequency F depends only on the Peclet number Pe with a power law. The exponent of Pe clearly changes from 2/3 to 1 around the critical Peclet number, indicating that the crossover reflects the competition of thermal fluctuation and shear flow. The presented numerical results agree well with our theoretical analysis based on Jeffery's work.
Effects of Advanced Oxidation Processes on the Decomposition Properties of Organic Compounds with Different Molecular Structures in Water  [PDF]
Harufumi Suzuki, Shoichi Yamagiwa, Sadao Araki, Hideki Yamamoto
Journal of Water Resource and Protection (JWARP) , 2016, DOI: 10.4236/jwarp.2016.89067
Abstract: Studies to decompose persistent organic pollutants in wastewater from chemical factories by using Advanced Oxidation Processes (AOPs) have recently been performed. Oxidation reactions involving ozone and OH radicals and cleavage caused by UV are the main decomposition reactions that occur in AOPs using ozone and UV. The mechanisms through which organic compounds are decomposed in AOPs are complicated and difficult to understand because various decomposition reactions occur simultaneously. The Total Organic Carbon (TOC) removal efficiencies achieved in several different AOPs were evaluated in this study. The TOC removal efficiencies were different for organic compounds with different chemical structures. The TOC was more effectively removed when aromatic compounds were treated using the O3-UV-TiO2 process than when using the other AOPs, and the TOC was removed more effectively by the O3-UV process than by the UV-TiO2 process. However, the TOC was removed more effectively when open-chain compounds were treated using the UV-TiO2 process than using the O3-UV process, and the UV-TiO2 and O3-UV-TiO2 processes resulted in similar TOC removal efficiencies. Therefore, it is necessary to use the O3-UV-TiO2 process to decompose aromatic compounds as quickly as possible. On the other hand, the UV-TiO2 process degraded the open-chain compounds most effectively, and the O3-UV-TiO2 process did not need to decompose open-chain compounds. Moreover, the TOC of aromatic compounds was removed more slowly than that of open-chain compounds. The TOC removal efficiency increased with decreasing the number of carbon atoms in the molecule. The TOC removal efficiencies increased in order of the organic compounds containing methyl groups, aldehyde groups and carboxyl groups. The removal of the TOC when organic compounds were treated using the O3-UV-TiO2 process followed pseudo-zero-order kinetics.
Deficits in Magnocellular Pathway in Developmental Dyslexia: A Functional Magnetic Resonance Imaging-Electroencephalography Study  [PDF]
Hisako Yamamoto, Yosuke Kita, Tomoka Kobayashi, Hiroko Yamazaki, Makiko Kaga, Hideki Hoshino, Takashi Hanakawa, Hitoshi Yamamoto, Masumi Inagaki
Journal of Behavioral and Brain Science (JBBS) , 2013, DOI: 10.4236/jbbs.2013.32017
Abstract:

Background: Magnocellular deficit theory is among the different hypotheses that have been proposed to explain the pathophysiology of developmental dyslexia (DD). Dysfunction of the magnocellular system in DD has been investigated using mainly visual evoked potentials (VEPs), particularly transient VEPs, although recently abnormal steady-state VEPs have also been reported. The brain regions responsible for the abnormal VEPs in DD have yet to be elucidated, however. In this study, we performed functional magnetic resonance imaging and electroencephalography (fMRI-EEG) simultaneously to elucidate the brain areas that were found in a previous study to be activated through stimulation of the magnocellular system, and then investigated the mechanism involved in the dysfunction seen in DD.Methods: Subjects were 20 healthy individuals (TYP group; 13 men, 7 women; mean ± standard deviation age, 26.3 ± 5.53 years) and 2 men with DD (aged 42 and 30 years). Images of brain activity were acquired with 3-Tesla MRI while the viewing the reversal of low-spatial frequency and low-contrast black-and-white sinusoidal gratings. EEG was recorded concurrently to obtain steady-state VEPs.Results: Stimulus frequency-dependent VEPs were observed in the posterior region of the brain in the TYP group; however, VEP amplitudes in both DD patients were clearly smaller than those in TYP. fMRI images revealed that both the primary and secondary visual cortices were activated by black-and- white sinusoidal gratings in the TYP group, whereas activity in the visual cortex overall was reduced in both DD patients.Conclusions: Present low spatial and high reversal frequency visual stimuli activated the primary

Replicated association of the single nucleotide polymorphism in PNLIP with marbling in Niigata population of Japanese Black beef cattle  [PDF]
Hideki Tanomura, Youji Muramatsu, Takuji Yamamoto, Takeshi Ohta, Hiroyuki Kose, Takahisa Yamada
Open Journal of Animal Sciences (OJAS) , 2013, DOI: 10.4236/ojas.2013.32013
Abstract:

Marbling is regarded as an economically important trait of beef cattle inJapan, and measured as a beef marbling score (BMS). Our previous study reported an association between a single nucleotide polymorphism (SNP), rs4164 8172, in the pancreatic lipase (PNLIP) gene and the BMS level, using the Japanese Black beef cattle population of Oita prefecture. Further, we showed that the T allele at the rs41648172 SNP is associated with a high level of the BMS. Thus, we suggested that the rs41648172 SNP seems to be a candidate marker for marker-assisted selection. Our present study was designed to investigate whether this association could be replicated in other independent Japanese Black cattle population and analyze the effect of the SNP genotypes on the carcass traits other than the BMS. We detected the marginally significant effect of the genotypes of the rs41648172 SNP on the BMS level by using the Japanese Black beef cattle population of Niigata prefecture (P = 0.0919), and obtained the result of the T allele associated with an increase in the BMS level, consistent with our previous data. In addition, we showed no significant association of the SNP with the subcutaneous fat thickness, carcass weight, rib eye area, rib thickness and yield estimate in the Japanese Black beef cattle population ofNiigataprefecture. Thus, we concluded that the rs41648172 SNP was useful for effective marker-assisted selection to increase the BMS level in Japanese Black beef cattle, based

Separability of Rotational Effects on a Gravitational Lens
Hideki Asada,Masumi Kasai,Tatsuya Yamamoto
Physics , 2003, DOI: 10.1103/PhysRevD.67.043006
Abstract: We derive the deflection angle up to $O(m^2a)$ due to a Kerr gravitational lens with mass $m$ and specific angular momentum $a$. It is known that at the linear order in $m$ and $a$ the Kerr lens is observationally equivalent to the Schwarzschild one because of the invariance under the global translation of the center of the lens mass. We show, however, nonlinear couplings break the degeneracy so that the rotational effect becomes in principle separable for multiple images of a single source. Furthermore, it is distinguishable also for each image of an extended source and/or a point source in orbital motion. In practice, the correction at $O(m^2a)$ becomes $O(10^{-10})$ for the supermassive black hole in our galactic center. Hence, these nonlinear gravitational lensing effects are too small to detect by near-future observations.
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