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Search Results: 1 - 10 of 51054 matches for " Y. Imai "
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A Necessary Condition for existence of Lie Symmetries in Quasihomogeneous Systems of Ordinary Differential Equations
Y. Hirata,K. Imai
Physics , 2001, DOI: 10.1143/JPSJ.71.2396
Abstract: Lie symmetries for ordinary differential equations are studied. In systems of ordinary differential equations, there do not always exist non-trivial Lie symmetries around equilibrium points. We present a necessary condition for existence of Lie symmetries analytic in the neighbourhood of an equilibrium point. In addition, this result can be applied to a necessary condition for existence of a Lie symmetry in quasihomogeneous systems of ordinary differential equations. With the help of our main theorem, it is proved that several systems do not possess any analytic Lie symmetries.
Constructing Student Personal Course Scheduling Problem with Spreading Activation on a Course Network
Hori Y.,Nakayama T.,Imai Y.
Lecture Notes in Engineering and Computer Science , 2010,
150 mM HCO3- - How Does the Pancreas Do It? Clues from Computer Modelling of the Duct Cell
Sohma Y,Gray MA,Imai Y,Argent BE
JOP Journal of the Pancreas , 2001,
Abstract: transmembrane conductance regulator (CFTR) is highly expressed in the pancreatic ductal epithelium and plays a key role in ductal HCO(3)(-) secretion. In humans, the pancreatic duct secretes near isotonic NaHCO(3). Experimental data suggests that HCO(3)(-) secretion occurs via apical Cl(-)/HCO(3)(-) exchangers working in parallel with Cl(-) channels (CFTR and calcium activated chloride channels, CaCC). Programming the currently available experimental data into our computer model (based on network thermodynamics) shows that while the anion exchanger/Cl(-) channel mechanism will produce a relatively large volume of a HCO(3)(-)-rich fluid, it can only raise the luminal HCO(3)(-) concentration up to about 70 mM. To achieve secretion of about 150 mM NaHCO(3) it is necessary to modulate the properties of the apical membrane transporters as the secreted fluid flows down the ductal system. On the basis of our computer simulations, we propose that HCO(3)(-) secretion occurs mainly via the exchanger in duct segments near the acini (luminal HCO(3)(-) concentration up to about 70 mM), but mainly via channels further down the ductal tree (raising luminal HCO(3)(-) to about 150 mM). We speculate that the switch between these two secretory mechanisms is controlled by a series of luminal signals (e.g. pH, HCO(3)(-) concentration) acting on the apical membrane transporters in the duct cell.
Large Thermoelectric Power Factor in TiS2 Crystal with Nearly Stoichiometric Composition
H. Imai,Y. Shimakawa,Y. Kubo
Physics , 2001, DOI: 10.1103/PhysRevB.64.241104
Abstract: A TiS$_{2}$ crystal with a layered structure was found to have a large thermoelectric power factor.The in-plane power factor $S^{2}/ \rho$ at 300 K is 37.1~$\mu$W/K$^{2}$cm with resistivity ($\rho$) of 1.7 m$\Omega$cm and thermopower ($S$) of -251~$\mu$V/K, and this value is comparable to that of the best thermoelectric material, Bi$_{2}$Te$_{3}$ alloy. The electrical resistivity shows both metallic and highly anisotropic behaviors, suggesting that the electronic structure of this TiS$_{2}$ crystal has a quasi-two-dimensional nature. The large thermoelectric response can be ascribed to the large density of state just above the Fermi energy and inter-valley scattering. In spite of the large power factor, the figure of merit, $ZT$ of TiS$_{2}$ is 0.16 at 300 K, because of relatively large thermal conductivity, 68~mW/Kcm. However, most of this value comes from reducible lattice contribution. Thus, $ZT$ can be improved by reducing lattice thermal conductivity, e.g., by introducing a rattling unit into the inter-layer sites.
Trochanteric Fracture of a Congenital/Developmental Dislocation of the Hip in an Elderly Woman: A Case Report  [PDF]
Kazuhiro Imai
Open Journal of Orthopedics (OJO) , 2011, DOI: 10.4236/ojo.2011.11001
Abstract: An 87-year-old woman with a residual dislocated hip suffered a trochanteric fracture on the ipsilateral side. The fracture was treated by open reduction and internal fixation surgery with good results. To treat a proximal femoral fracture of the residual dislocated hip in an elderly patient, the patient’s overall status, pre-fracture ability, hip joint configuration, and fracture pattern should be considered.
In Vivo Investigation of Zr-Based Bulk Metallic Glasses Sub-Periosteally Implanted on the Bone Surface  [PDF]
Kazuhiro Imai
Journal of Materials Science and Chemical Engineering (MSCE) , 2016, DOI: 10.4236/msce.2016.41009

Bulk metallic glasses (BMG) show higher strength and lower Young’s modulus than SUS 316L stainless steel and Ti-6Al-4V alloys. This study aimed to investigate the reaction of Zr-based BMG sub-periosteally implanted on the surface of the rat femur, thereby evaluate the possibility of the BMG as biomaterials for osteosynthetic devices. Zr65Al7.5Ni10Cu17.5 BMG ribbons with 10 mm length, 2 mm width and 0.5 mm thickness were implanted sub-periosteally on the femur surface in three male Wistar rats for 6 weeks. Systemic effects were evaluated by measuring Cu and Ni levels in the blood, and local effects were evaluated by the histological observation of the surrounding soft tissues in contact with the BMG. The reaction of the surface of the BMG was examined with scanning electron microscopy. No increase of Cu and Ni levels in the blood was recognized. In the scanning electron microscopy observation, spherical deposits which were considered as sodium chloride crystals were observed. Neither breakage nor pitting corrosion was noted. BMG will be a promising metallic biomaterial for osteosynthetic device that must be removed.

ATCA survey of water masers in the Large Magellanic Cloud
H. Imai,Y. Katayama,S. P. Ellingsen,Y. Hagiwara
Physics , 2013, DOI: 10.1093/mnrasl/slt027
Abstract: We have analysed archival data taken with the Australia Telescope Compact Array (ATCA) during 2001--2003 and detected nine new interstellar and circumstellar water masers in the LMC. This takes the total number of star formation water masers in the LMC to 23, spread over 14 different star forming regions and three evolved stars. Three water maser sources (N105a/MC23, N113/MC24, N157a/MC74) have been detected in all the previous observations that targeted these sites, although all show significant variability on timescales of decades. The total number of independent water maser sources now known in the LMC means that through very long baseline interferometry astrometric measurements it will be possible to construct a more precise model of the galactic rotation of the LMC and its orbital motion around the Milky Way Galaxy.
Quantum Corrections on Fuzzy Sphere
T. Imai,Y. Kitazawa,Y. Takayama,D. Tomino
Physics , 2003, DOI: 10.1016/S0550-3213(03)00491-7
Abstract: We investigate quantum corrections in non-commutative gauge theory on fuzzy sphere. We study translation invariant models which classically favor a single fuzzy sphere with U(1) gauge group. We evaluate the effective actions up to the two loop level. We find non-vanishing quantum corrections at each order even in supersymmetric models. In particular the two loop contribution favors U(n) gauge group over U(1) contrary to the tree action in a deformed IIB matrix model with a Myers term. We further observe close correspondences to 2 dimensional quantum gravity.
Carrier density change in Colossal Magnetoresistive Pyrochlore Tl2Mn2O7
H. Imai,Y. Shimakawa,Yu. V. Sushko,Y. Kubo
Physics , 1999, DOI: 10.1103/PhysRevB.62.12190
Abstract: Hall resistivity and magneto-thermopower have been measured for colossal magnetoresistive Tl2Mn2O7 over wide temperature and magnetic-field ranges. These measurements revealed that a small number of free electron-like carriers is responsible for the magneto-transport properties. In contrast to perovskite CMR materials, the anomalous Hall coefficient is negligible even in the ferromagnetic state due to negligibly small skew scattering. The characteristic feature in Tl2Mn2O7 is that the carrier density changes with temperature and the magnetic field. The carrier density increases around TC as the temperature is lowered or as the magnetic field is increased, which explains the CMR of this material. The conduction-band-edge shift, which is caused by the strong s-d interaction between localized Mn moments and s-like conduction electrons, is a possible mechanism for the carrier density change.
Differential responses of serum gamma-glutamyltransferase to alcohol intake in Japanese males.
Matsuka Y,Wang DH,Suganuma N,Imai K
Acta Medica Okayama , 2003,
Abstract: We studied the association of gamma-glutamyltransferase (GGT) and other serum markers of liver injury with daily alcohol consumption in a healthy population of 1,043 Japanese males. A positive correlation between daily alcohol consumption and biochemical markers, such as log GGT (r = 0.432), log AST (r = 0.244) or log LAP (r = 0.246), was seen in all drinkers. However, there was a negative correlation, such as log GGT (r = -0.434), log AST (r = -0.424) or log LAP (r = -0.430), in heavy drinkers who consumed more than 70 g ethanol a day. On the other hand, a positive correlation, such as log GGT (r = 0.426), log AST (r = 0.247) or log LAP (r = 0.216) was found in moderate drinkers who consumed less than 70 g ethanol a day. Interestingly, there was a tendency toward negative association between alcohol consumption and the Tokyo University ALDH2 Phenotype Screening Test (TAST) score in the heavy drinkers, and there was a tendency toward positive association between GGT and TAST score in this group. Our results suggest that there are 2 groups of drinkers, those with elevated GGT (good responders) and those with normal GGT (poor responders) despite heavy drinking.
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