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Search Results: 1 - 10 of 1108 matches for " Takahiko Ogawa "
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Tetrachlorido[(diphenylphosphino)diphenylphosphine oxide-κO]zirconium(IV) benzene monosolvate. Corrigendum
Takahiko Ogawa,Yuji Kajita,Hideki Masuda
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810002230
Abstract: The chemical name of the title compound in the paper by Ogawa, Kajita & Masuda [Acta Cryst. (2009), E65, m1129] is corrected.
Tetrachlorido[(diphenylphosphino)diphenylphosphine oxide-κO]zirconium(IV) benzene monosolvate
Takahiko Ogawa,Yuji Kajita,Hideki Masuda
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809031882
Abstract: In the title centrosymmetric mononuclear ZrIV compound, [ZrCl4{P(O)(C6H5)2P(C6H5)2}2]·C6H6, the central ZrIV ion is coordinated by two O atoms from two symmetry-related (diphenylphosphino)diphenylphosphine ligands and four Cl atoms in a distorted octahedral geometry with the four Cl atoms in the equatorial positions. The molecule lies about a center of inversion and the benzene solvent molecule about another center of inversion. The P=O bond [1.528 (2) ] is slightly longer than a typical P=O double bond (average 1.500 ).
The Impact of Travel Time on Geographic Distribution of Dialysis Patients
Saori Kashima, Masatoshi Matsumoto, Takahiko Ogawa, Akira Eboshida, Keisuke Takeuchi
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047753
Abstract: Backgrounds The geographic disparity of prevalence rates among dialysis patients is unclear. We evaluate the association between travel time to dialysis facilities and prevalence rates of dialysis patients living in 1,867 census areas of Hiroshima, Japan. Furthermore, we study the effects of geographic features (mainland or island) on the prevalence rates and assess if these effects modify the association between travel time and prevalence. Methods The study subjects were all 7,374 people that were certified as the “renal disabled” by local governments in 2011. The travel time from each patient to the nearest available dialysis facility was calculated by incorporating both travel time and the capacity of all 98 facilities. The effect of travel time on the age- and sex-adjusted standard prevalence rate (SPR) and 95% confidence intervals (CIs) at each census area was evaluated in two-level Poisson regression models with 1,867 census areas (level 1) nested within 35 towns or cities (level 2). The results were adjusted for area-based parameters of socioeconomic status, urbanity, and land type. Furthermore, the SPR of dialysis patients was calculated in each specific subgroup of population for travel time, land type, and combination of land type and travel time. Results In the regression analysis, SPR decreased by 5.2% (95% CI: ?7.9–?2.3) per 10-min increase in travel time even after adjusting for potential confounders. The effect of travel time on prevalence was different in the mainland and island groups. There was no travel time-dependent SPR disparity on the islands. The SPR among remote residents (>30 min from facilities) in the mainland was lower (0.77, 95% CI: 0.71–0.85) than that of closer residents (≤30 min; 0.95, 95% CI: 0.92–0.97). Conclusions The prevalence of dialysis patients was lower among remote residents. Geographic difficulties for commuting seem to decrease the prevalence rate.
The impact of rural hospital closures on equity of commuting time for haemodialysis patients: simulation analysis using the capacity-distance model
Matsumoto Masatoshi,Ogawa Takahiko,Kashima Saori,Takeuchi Keisuke
International Journal of Health Geographics , 2012, DOI: 10.1186/1476-072x-11-28
Abstract: Background Frequent and long-term commuting is a requirement for dialysis patients. Accessibility thus affects their quality of lives. In this paper, a new model for accessibility measurement is proposed in which both geographic distance and facility capacity are taken into account. Simulation of closure of rural facilities and that of capacity transfer between urban and rural facilities are conducted to evaluate the impacts of these phenomena on equity of accessibility among dialysis patients. Methods Post code information as of August 2011 of all the 7,374 patients certified by municipalities of Hiroshima prefecture as having first or third grade renal disability were collected. Information on post code and the maximum number of outpatients (capacity) of all the 98 dialysis facilities were also collected. Using geographic information systems, patient commuting times were calculated in two models: one that takes into account road distance (distance model), and the other that takes into account both the road distance and facility capacity (capacity-distance model). Simulations of closures of rural and urban facilities were then conducted. Results The median commuting time among rural patients was more than twice as long as that among urban patients (15 versus 7 minutes, p < 0.001). In the capacity-distance model 36.1% of patients commuted to the facilities which were different from the facilities in the distance model, creating a substantial gap of commuting time between the two models. In the simulation, when five rural public facilitiess were closed, Gini coefficient of commuting times among the patients increased by 16%, indicating a substantial worsening of equity, and the number of patients with commuting times longer than 90 minutes increased by 72 times. In contrast, closure of four urban public facilities with similar capacities did not affect these values. Conclusions Closures of dialysis facilities in rural areas have a substantially larger impact on equity of commuting times among dialysis patients than closures of urban facilities. The accessibility simulations using thecapacity-distance model will provide an analytic framework upon which rational resource distribution policies might be planned.
A study of the changes in the cause of peptic ulcer bleeding
Haruka Fujinami,Takahiko Kudo,Ayumu Hosokawsa,Kohei Ogawa
World Journal of Gastrointestinal Endoscopy , 2012, DOI: 10.4253/wjge.v4.i7.323
Abstract: AIM: To clarify the frequency of and changes in the cause of peptic ulcer bleeding. METHODS: This study retrospectively evaluated the out- and inpatients who underwent endoscopy between 2002 to 2008. The subjects were patients presenting with peptic ulcer bleeding. The details of these patients were obtained from their endoscopic reports and medical records. RESULTS: The rates of Helicobacter pylori (H. pylori) infection were significantly low (P = 0.039), while the proportion of nonsteroidal antiinflammatory drugs (NSAIDs) users and vascular disease significantly increased over the period studied (P = 0.034 and P = 0.04, respectively). However, there was no significant difference in the proportion of low-dose aspirin users (P = 0.832). CONCLUSION: It’s found that the primary cause of peptic ulcer bleeding changed from H. pylori infection to use of NSAIDs over the 7-year period of study. It seems that the number of low-dose aspirin users has increased with the increase in the proportion of vascular disease. It is necessary to take measures to prevent peptic ulcer bleeding among NSAIDs and low dose aspirin users.
Microwave Effect for Glycosylation Promoted by Solid Super Acid in Supercritical Carbon Dioxide
Hiroshi Hinou,Naohiro Saito,Masato Ogawa,Takahiko Maeda,Shin-Ichiro Nishimura
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10125285
Abstract: The effects of microwave irradiation (2.45 GHz, 200 W) on glycosylation promoted by a solid super acid in supercritical carbon dioxide was investigated with particular attention paid to the structure of the acceptor substrate. Because of the symmetrical structure and high diffusive property of supercritical carbon dioxide, microwave irradiation did not alter the temperature of the reaction solution, but enhanced reaction yield when aliphatic acceptors are employed. Interestingly, the use of a phenolic acceptor under the same reaction conditions did not show these promoting effects due to microwave irradiation. In the case of aliphatic diol acceptors, the yield seemed to be dependent on the symmetrical properties of the acceptors. The results suggest that microwave irradiation do not affect the reactivity of the donor nor promoter independently. We conclude that the effect of acceptor structure on glycosylation yield is due to electric delocalization of hydroxyl group and dielectrically symmetric structure of whole molecule.
Significant Improvement of Mechanical Properties for Polyvinyl Alcohol Film Prepared from Freeze/Thaw Cycled Gel  [PDF]
Taishi Fukumori, Takahiko Nakaoki
Open Journal of Organic Polymer Materials (OJOPM) , 2013, DOI: 10.4236/ojopm.2013.34018

The mechanical properties of polyvinyl alcohol (PVA) films prepared by evaporating water from freeze/thaw cycled gel were investigated as a function of the number of freeze/thaw cycles. The maximum stress of the PVA film prepared by freeze/thaw cycling was larger than that prepared without the freeze/thaw cycle process. The largest maximum stress was 46.2 MPa for a film prepared with 10 freeze/thaw cycles, which was twice as large as that for a cast PVA film without freeze/thaw cycling (22.3 MPa). This is due to the formation of small crystallites during the freeze/thaw cycle process. Furthermore, when the film was annealed at 130°C, the maximum stress was as high as 181 MPa which was comparable to that for PVA films prepared using additives. The crystallinity is not the main factor that determines the maximum stress for either the non-annealed or annealed freeze/thaw cycled films, but the glass transition temperature is well correlated with the maximum stress, irrespective of the annealing process. This is due to the different molecular morphology; the non-annealed freeze/thaw cycled film consists of many small crystallites, but the annealed film consists of larger crystallites formed during the annealing process.

Active Control Method for Critical Cornering Range  [PDF]
Takahiko Yoshino, Hiromichi Nozaki
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.68043

It has been reported that steering systems with derivative terms have a heightened lateral acceleration and yaw rate response in the normal driving range. However, in ranges where the lateral acceleration is high, the cornering force of the front wheels decreases and hence becomes less effective. Therefore, we applied traction control for the inner and outer wheels based on the steering angle velocity to improve the steering effectiveness at high lateral accelerations. An experiment using a driving simulator showed that the vehicle’s yaw rate response improved for a double lane change to avoid a hazard; this improves hazard avoidance performance. Regarding improved vehicle control in the cornering margins, traction control for the inner and outer wheels is being developed further, and much research and development has been reported. However, in the total skid margin, where few margin remains in the forward and reverse drive forces on the tires, spinout is unavoidable. Therefore, we applied tire camber angle control to improve vehicle maneuverability in the total skid margin. An experiment using a driving simulator has confirmed that the vehicle’s lateral acceleration at the turning limit can be improved by controlling the camber angle. Because of this, camber angle control promises to be more effective than traction control for the inner and outer wheels. By applying this type of steering control, it is possible to increase maneuverability and stability in the cornering margins.

Camber Angle Control Method Corresponding to the Electric Vehicle Age  [PDF]
Takahiko Yoshino, Hiromichi Nozaki
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.68049
Abstract: In recent years, the conversion of vehicles to electric power has been accelerating, and if a full conversion to electric power is achieved, further advancements in vehicle kinematic control technology are expected. Therefore, it is thought that kinematic performance in the critical cornering range could be further improved by significantly controlling not only the steering angle but also the camber angle of the tires through the use of electromagnetic actuators. This research focused on a method of ground negative camber angle control that is proportional to the steering angle as a technique to improve maneuverability and stability to support the new era of electric vehicles, and the effectiveness thereof was clarified. As a result, it was found that in the critical cornering range as well, camber angle control can control both the yaw moment and lateral acceleration at the turning limit. It was also confirmed that both stability and the steering effect in the critical cornering range are improved by implementing ground negative camber angle control that is proportional to the steering angle using actuators. Dramatic improvements in cornering limit performance can be achieved by implementing ground negative camber angle control that is proportional to the steering angle.
Variable Gear Ratio Control Using Vehicle Body Slip Angle  [PDF]
Takahiko Yoshino, Hiromichi Nozaki
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.68046

Vehicles with variable steering characteristics have long been studied and compared with those having typical fixed gear ratio steering, and the variable gear ratio properties are reported to have improved maneuverability and stability in high-speed lane changes and on slippery low-friction road surfaces. However, it is not clear how gear ratios should be set for individual vehicle characteristics. Therefore, the present study has investigated a variable steering gear system using body slip angle feedback for the purpose of improved maneuverability and stability in the critical cornering range and upwards, in excess of the critical limit, and into the countersteer range. The results of a driving simulator experiment show that the steering effect improves and maneuverability and stability increase in the critical cornering range and upwards, in excess of the critical limit, and into the countersteer range by applying linear-variable control to the steering ratio from a body slip angle of 5?. This result is seen both in double lane changes, such as in hazard avoidance, and in J-turns with long drifting. Moreover, it shows an improvement in drift controllability through prompt countersteering. Overall, the present system can enhance the driver’s hazard avoidance capability.

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