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Search Results: 1 - 10 of 2177 matches for " Koichi Okamoto "
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Techniques for Avoiding Saccular Extended Obstruction at the Anastomotic Site of Functional End-to-End Anastomosis  [PDF]
Koichi Yoshida, Kenichi Ietsugu, Jyunpei Okamoto, Saki Hayashi, Yoshihide Asaumi, Naohiro Ota, Hiroyuki Sugawara, Satoshi Tabata, Masahiro Kaneki, Mitsuaki Sakatoku, Kaoru Kiyohara
Surgical Science (SS) , 2017, DOI: 10.4236/ss.2017.87033
Abstract: Saccular extended obstruction is generated when the anastomotic site of functional end-to-end anastomosis is extended saccularly and blocked by intestinal contents. This is a specific complication of functional end-to-end anastomosis. Saccular extended obstruction of the anastomotic site of func-tional end-to-end anastomosis causes postoperative intestinal obstruction. Saccular extended obstruction places a heavy burden on patients because surgery is necessary for treatment of intestinal obstruction due to saccular extended obstruction. However, saccular extended obstruction is not a commonly recognized complication. The greatest factor contributing to the development of saccular extended obstruction is an acute angle between the portions of the intestinal tract oral and aboral to the anastomotic site. When this angle approaches obtuse angle, preferably close to a straight line, stagnation of the intestinal contents does not occur at the anastomotic site of functional end-to-end anastomosis and saccular extended obstruction is avoided. For making the angle of anastomotic intestinal tracts obtuse or straight, it may be effective that the entry hole of stapling suture instrument creating the anastomotic stoma is closed perpendicular to the intestinal axis.
Association between Circulating Fibroblast Growth Factor 23, α-Klotho, and the Left Ventricular Ejection Fraction and Left Ventricular Mass in Cardiology Inpatients
Kensaku Shibata, Shu-ichi Fujita, Hideaki Morita, Yusuke Okamoto, Koichi Sohmiya, Masaaki Hoshiga, Nobukazu Ishizaka
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0073184
Abstract: Background Fibroblast growth factor 23 (FGF23), with its co-receptor Klotho, plays a crucial role in phosphate metabolism. Several recent studies suggested that circulating FGF23 and α-Klotho concentrations might be related to cardiovascular abnormalities in patients with advanced renal failure. Purpose Using data from 100 cardiology inpatients who were not undergoing chronic hemodialysis, the association of circulating levels of FGF23, α-Klotho, and other calcium-phosphate metabolism-related parameters with the left ventricular ejection fraction (LVEF) and left ventricular mass (LVM) was analyzed. Methods and Results LVEF was measured using the modified Simpson method for apical 4-chamber LV images and the LVM index (LVMI) was calculated by dividing the LVM by body surface area. Univariate analysis showed that log transformed FGF23, but not that of α-Klotho, was significantly associated with LVEF and LVMI with a standardized beta of ?0.35 (P<0.001) and 0.26 (P<0.05), respectively. After adjusting for age, sex, estimated glomerular filtration rate, and serum concentrations of intact parathyroid hormone, and 25-hydroxyvitamin D as covariates into the statistical model, log-transformed FGF23 was found to be a statistically positive predictor for decreased left ventricular function and left ventricular hypertrophy. Conclusions In cardiology department inpatients, circulating FGF23 concentrations were found to be associated with the left ventricular mass and LVEF independent of renal function and other calcium-phosphate metabolism-related parameters. Whether modulation of circulating FGF23 levels would improve cardiac outcome in such a high risk population awaits further investigation.
Beclin 1 and UVRAG Confer Protection from Radiation-Induced DNA Damage and Maintain Centrosome Stability in Colorectal Cancer Cells
Jae Myung Park, David Tougeron, Shengbing Huang, Koichi Okamoto, Frank A. Sinicrope
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100819
Abstract: Beclin 1 interacts with UV-irradiation-resistance-associated gene (UVRAG) to form core complexes that induce autophagy. While cells with defective autophagy are prone to genomic instability that contributes to tumorigenesis, it is unknown whether Beclin1 or UVRAG can regulate the DNA damage/repair response to cancer treatment in established tumor cells. We found that siRNA knockdown of Beclin 1 or UVRAG can increase radiation-induced DNA double strand breaks (DSBs), shown by pATM and γH2Ax, and promote colorectal cancer cell death. Furthermore, knockdown of Beclin 1, UVRAG or ATG5 increased the percentage of irradiated cells with nuclear foci expressing 53BP1, a marker of nonhomologous end joining but not RAD51 (homologous recombination), compared to control siRNA. Beclin 1 siRNA was shown to attenuate UVRAG expression. Cells with a UVRAG deletion mutant defective in Beclin 1 binding showed increased radiation-induced DSBs and cell death compared to cells with ectopic wild-type UVRAG. Knockdown of Beclin 1 or UVRAG, but not ATG5, resulted in a significant increase in centrosome number (γ-tubulin staining) in irradiated cells compared to control siRNA. Taken together, these data indicate that Beclin 1 and UVRAG confer protection against radiation-induced DNA DSBs and may maintain centrosome stability in established tumor cells.
Magnetic Field versus Temperature Phase Diagram of the Spin-1/2 Alternating Chain Compound F5PNN
Yasuo Yoshida,Tatsuya Kawae,Yuko Hosokoshi,Katsuya Inoue,Nobuya Maeshima,Koichi Okunishi,Kiyomi Okamoto,Toru Sakai
Physics , 2007,
Abstract: We have measured the specific heat of the S = 1/2 alternating Heisenberg antiferromagnetic chain compound pentafluorophenyl nitronyl nitroxide in magnetic fields using a single crystal and powder. A sharp peak due to field-induced magnetic ordering (FIMO) is observed in both samples. The H-T phase boundary of the FIMO of the single crystal is symmetric with respect to the central field of the gapless field region HC1 < H < HC2, whereas it is distorted for the powder whose ordering temperatures are lower. An analysis employing calculations based on the finite temperature density matrix renormalization group indicates the possibility of novel incommensurate ordering due to frustration in the powder around the central field.
Magnetization Plateaus in the Spin-1/2 Kagome Antiferromagnets: Volborthite and Vesignieite
Yoshihiko Okamoto,Masashi Tokunaga,Hiroyuki Yoshida,Akira Matsuo,Koichi Kindo,Zenji Hiroi
Physics , 2011, DOI: 10.1103/PhysRevB.83.180407
Abstract: The magnetization of two spin-1/2 kagome antiferromagnets, volborthite and vesignieite, has been measured in pulsed magnetic fields up to 68 T. A magnetization plateau is observed for each compound near the highest magnetic field. Magnetizations at saturation are approximately equal to 0.40Ms for both compounds, where Ms is the fully saturated magnetization, irrespective of a difference in the distortion of the kagome lattice between the two compounds. It should be noted that these values of magnetizations are significantly larger than Ms/3 predicted theoretically for the one-third magnetization plateau in the spin-1/2 kagome antiferromagnet. The excess magnetization over Ms/3 is nearly equal to the sum of the magnetizations gained at the second and third magnetization steps in volborthite, suggesting that there is a common origin for the excess magnetization and the magnetization steps.
Case Studies of Energy Saving and CO2 Reduction by Cogeneration and Heat Pump Systems  [PDF]
Satoru Okamoto
Open Journal of Energy Efficiency (OJEE) , 2013, DOI: 10.4236/ojee.2013.22014
Abstract:

This paper describes two case studies: 1) a cogeneration system of a hospital and 2) a heat pump system installed in an aquarium that uses seawater for latent heat storage. The cogeneration system is an autonomous system that combines the generation of electrical, heating, and cooling energies in a hospital. Cogeneration systems can provide simultaneous heating and cooling. No technical obstacles were identified for implementing the cogeneration system. The average ratio between electric and thermal loads in the hospital was suitable for the cogeneration system operation. An analysis performed for a non-optimized cogeneration system predicted large potential for energy savings and CO2 reduction. The heat pump system using a low-temperature unutilized heat source is introduced on a heat source load responsive heat pump system, which combines a load variation responsive heat pump utilizing seawater with a latent heat-storage system (ice and water slurry), using nighttime electric power to level the electric power load. The experimental coefficient of performance (COP) of the proposed heat exchanger from the heat pump system, assisted by using seawater as latent heat storage for cooling, is discussed in detail.

Energy-Saving and Economical Evaluations of a Ceramic Gas Turbine Cogeneration Plant  [PDF]
Satoru Okamoto
Open Journal of Energy Efficiency (OJEE) , 2013, DOI: 10.4236/ojee.2013.22012
Abstract:

A ceramic gas turbine can save energy because of its high thermal efficiency at high turbine inlet temperatures. This paper deals with the thermodynamic and economic aspects of a ceramic gas turbine cogeneration system. Here cogeneration means the simultaneous production of electrical en-ergy and useful thermal energy from the same facility. The thermodynamic performance of a ceramic gas turbine cycle is assessed using a computer model. This model is used in parametric studies of performance under partial loads and at various inlet air temperatures. The computed performance is compared to the measured performance of a conventional gas turbine cycle. Then, an economic evaluation of a ceramic gas turbine cogeneration system is investigated. Energy savings provided by this system are estimated on the basis of the distributions of heat/power ratios. The computed economic evaluation is compared to the actual economic performance of a conventional system in which boilers produce the required thermal energy and electricity is purchased from a utility.

Human Physical Activity Measurement Method Based on Electrostatic Induction  [PDF]
Koichi Kurita
Journal of Sensor Technology (JST) , 2014, DOI: 10.4236/jst.2014.43013
Abstract:
In this study, an effective noncontact and nonattached technique that is based on electrostatic induction current generated during walking motion is proposed for the detection and assessment of human physical activity. In addition, a theoretical model is proposed for the electrostatic induction current generated owing to variation in the electric potential of the human body. The proposed electrostatic induction current model is compared with the theoretical model, and the proposed model is shown to effectively explain the behavior of the electrostatic induction current waveform. The normal walking motions of daily living are recorded with a portable sensor located in a regular house. The obtained results show that detailed information of physical activity such as a gait cycle can be estimated using our proposed technique. Additionally, the walking signal was measured when the subject walked with the ankle and knee fastened to a splint with bandages to simulate a limp. Therefore, the proposed technique, which is based on the detection of signal generated during walking, can be successfully employed to assess human physical activity.
Attractor-Based Simultaneous Design of the Minimum Set of Control Nodes and Controllers in Boolean Networks  [PDF]
Koichi Kobayashi
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.714131
Abstract: Design of control strategies for gene regulatory networks is a challenging and important topic in systems biology. In this paper, the problem of finding both a minimum set of control nodes (control inputs) and a controller is studied. A control node corresponds to a gene that expression can be controlled. Here, a Boolean network is used as a model of gene regulatory networks, and control specifications on attractors, which represent cell types or states of cells, are imposed. It is important to design a gene regulatory network that has desired attractors and has no undesired attractors. Using a matrix-based representation of BNs, this problem can be rewritten as an integer linear programming problem. Finally, the proposed method is demonstrated by a numerical example on a WNT5A network, which is related to melanoma.
Possible Effect of Pressure Solution on the Movement of a Canister in the Buffer of Geological Disposal System  [PDF]
Koichi Shin
International Journal of Geosciences (IJG) , 2017, DOI: 10.4236/ijg.2017.82006
Abstract: One of the major concepts of the geological disposal of high level radioactive waste is to enclose a metallic container with bentonite buffer which is considered to be impermeable and chemically stable. Since the average density of the container is around 6 to 7 and very heavy compared to bentonite, the scenario of container sinking has been evaluated because excess sinking makes short the pathway of nuclide migration in the bentonite and is detrimental to the safety of the disposal system. Previous considerations on container sinking have been made from the viewpoint of mechanical deformation of the bentonite. In this paper, a chemical deformation process is presented as another mechanism of container sinking, which has not been previously considered for the container sinking in the field of radioactive waste disposal. The chemical deformation mentioned in this paper is the deformation through the process of pressure solution of minerals constituting the buffer, transportation by diffusion and precipitation. That such chemical deformation is a ubiquitous phenomenon occurring in various scales in the crust of the earth will be shown through the review of previous works. Then, some future research topics will be suggested which would be required in order to evaluate the container sinking in the safety case for radioactive waste disposal.
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