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Search Results: 1 - 10 of 283 matches for " Hidetake Kurihara "
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An Essential Role of the Universal Polarity Protein, aPKCλ, on the Maintenance of Podocyte Slit Diaphragms
Tomonori Hirose, Daisuke Satoh, Hidetake Kurihara, Chiho Kusaka, Hiroko Hirose, Kazunori Akimoto, Taiji Matsusaka, Iekuni Ichikawa, Tetsuo Noda, Shigeo Ohno
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0004194
Abstract: Glomerular visceral epithelial cells (podocytes) contain interdigitated processes that form specialized intercellular junctions, termed slit diaphragms, which provide a selective filtration barrier in the renal glomerulus. Analyses of disease-causing mutations in familial nephrotic syndromes and targeted mutagenesis in mice have revealed critical roles of several proteins in the assembly of slit diaphragms. The nephrin–podocin complex is the main constituent of slit diaphragms. However, the molecular mechanisms regulating these proteins to maintain the slit diaphragms are still largely unknown. Here, we demonstrate that the PAR3–atypical protein kinase C (aPKC)–PAR6β cell polarity proteins co-localize to the slit diaphragms with nephrin. Furthermore, selective depletion of aPKCλ in mouse podocytes results in the disassembly of slit diaphragms, a disturbance in apico-basal cell polarity, and focal segmental glomerulosclerosis (FSGS). The aPKC–PAR3 complex associates with the nephrin–podocin complex in podocytes through direct interaction between PAR3 and nephrin, and the kinase activity of aPKC is required for the appropriate distribution of nephrin and podocin in podocytes. These observations not only establish a critical function of the polarity proteins in the maintenance of slit diaphragms, but also imply their potential involvement in renal failure in FSGS.
A Comparative Analysis of Glomerulus Development in the Pronephros of Medaka and Zebrafish
Koichiro Ichimura, Ekaterina Bubenshchikova, Rebecca Powell, Yayoi Fukuyo, Tomomi Nakamura, Uyen Tran, Shoji Oda, Minoru Tanaka, Oliver Wessely, Hidetake Kurihara, Tatsuo Sakai, Tomoko Obara
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045286
Abstract: The glomerulus of the vertebrate kidney links the vasculature to the excretory system and produces the primary urine. It is a component of every single nephron in the complex mammalian metanephros and also in the primitive pronephros of fish and amphibian larvae. This systematic work highlights the benefits of using teleost models to understand the pronephric glomerulus development. The morphological processes forming the pronephric glomerulus are astoundingly different between medaka and zebrafish. (1) The glomerular primordium of medaka - unlike the one of zebrafish - exhibits a C-shaped epithelial layer. (2) The C-shaped primordium contains a characteristic balloon-like capillary, which is subsequently divided into several smaller capillaries. (3) In zebrafish, the bilateral pair of pronephric glomeruli is fused at the midline to form a glomerulus, while in medaka the two parts remain unmerged due to the interposition of the interglomerular mesangium. (4) Throughout pronephric development the interglomerular mesangial cells exhibit numerous cytoplasmic granules, which are reminiscent of renin-producing (juxtaglomerular) cells in the mammalian afferent arterioles. Our systematic analysis of medaka and zebrafish demonstrates that in fish, the morphogenesis of the pronephric glomerulus is not stereotypical. These differences need be taken into account in future analyses of medaka mutants with glomerulus defects.
Is the Tokyo Foreign Exchange Market Efficient from Two Perspectives of Forward Bias and Anomaly?  [PDF]
Yutaka Kurihara
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.24067
Abstract: This paper examines the efficiency of the Tokyo Foreign Exchange Market from two perspectives. One is whether or not forward bias in this market has existed and the other is the effect of interventions in the market with a focus on whether or not a day-of-the-week anomaly exists in it. Empirical results show that forward exchange rates are a biased predictor of future spot exchange rates; however, there are some anomalies in the market. The findings suggest the conclusion that this market has not been completely efficient.
The Impact of Regional Trade Agreements on International Trade  [PDF]
Yutaka Kurihara
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.25094
Abstract: The gravity model of international trade states that bilateral trade flows based on the economic sizes and distances between two units can be used to examine reasons for international trade. Regional Trade Agreements (RTAs) have appeared recently and have increased markedly in number; however, despite their importance, little study has been performed to analyze the effects of RTAs on international trade. The difference between RTAs and world trade organizations (WTO) is important. Studies of currency integration have appeared recently; however, most assume that currency integration varies the level of international trade between countries by making the proportion constant. This paper eliminates this socalled constant hypothesis and indicates that RTAs alters the slope of the relationship between countries and promote international trade. Empirical analysis indicates that the proportion is not constant. Also, this study shows that RTAs promote international trade more in OECD countries than in non-OECD countries.
Is the WTO Truly Effective?  [PDF]
Yutaka Kurihara
iBusiness (IB) , 2012, DOI: 10.4236/ib.2012.42014
Abstract: Whether or not the World Trade Organization (WTO) has promoted international trade is under dispute. This article uses a revised traditional gravity model to conduct empirical examination of this problem and found that WTO has recently promoted international trade and that the degree of increase is larger in developed countries than in developing ones. Moreover, regional trade agreements (RTA), currency unions, GDP, and distance are related to the increase of international trade along with the effects of WTO activities. On the other hand, the effect of distance on international trade has been decreasing. Improvements in information technology (IT) may have influenced this finding.
Speed Control Method of Electric Vehicle for Improving Passenger Ride Quality  [PDF]
Hidetake Fuse, Tohru Kawabe, Masayuki Kawamoto
Intelligent Control and Automation (ICA) , 2017, DOI: 10.4236/ica.2017.81003
Abstract: This paper proposes the new speed control method of electric vehicles by generating the longitudinal speed pattern for improving the ride comfort against the longitudinal acceleration/deceleration. Since the longitudinal acceleration/deceleration of EVs causes the discomfort of passengers, reducing such bad effect of acceleration/deceleration acting on passengers is very important for not only the ride comfort of passengers but also vehicle running safety. The proposed method is applying the general optimal control theory and it generates the speed pattern for improving the passenger ride quality based on evaluating the variations of acceleration and the jerk which is time derivative of the acceleration. The effectiveness of the present method is demonstrated through numerical experiments compared with some conventional methods.
Improvement of Countrywide Vegetation Mapping over Japan and Comparison to Existing Maps  [PDF]
Ram C. Sharma, Keitarou Hara, Hidetake Hirayama
Advances in Remote Sensing (ARS) , 2018, DOI: 10.4236/ars.2018.73011
Abstract: This paper presents an improved classification and mapping of vegetation types for all of Japan by utilizing the Moderate-resolution Imaging Spectroradiometer (MODIS) data. The Nadir BRDF-Adjusted Reflectance (MCD43A4 product) data were compared to the conventional Surface Reflectance (MOD09A1/MOY09A1 products) data for the classification of vegetation types: evergreen coniferous forest, evergreen broadleaf forest, deciduous coniferous forest, deciduous broadleaf forest, shrubs, herbaceous, arable; and non-vegetation. Very rich spectral and temporal features were prepared from MCD43A4 and MOD09A1/MOY09A1 products. Random Forests classifier was employed for the classification of vegetation types with the support of ground truth data prepared in the research. Accuracy metrics—confusion matrix, overall accuracy, and kappa coefficient calculated through 10-fold cross-validation approach—were used for quantitative comparison of MCD43A4 and MOD09A1/MOY09A1 products. The cross-validation results indicated better performance of the MCD43A4 (Overall accuracy = 0.73; Kappa coefficient = 0.69) product than conventional MOD09A1/MOY09A1 products (Overall accuracy = 0.70; Kappa coefficient = 0.66) for the classification. McNemar’s test was also used to confirm a significant difference (p-value = 0.0003) between MCD43A4 and MOD09A1/MOY09A1 products. Based on these results, by utilizing the MCD43A4 features, a new vegetation map was produced for all of Japan. The newly produced map showed better accuracy than the extant, MODIS Land Cover Type product (MCD12Q1) and Global Land Cover by National Mapping Organizations (GLCNMO) product in Japan.
Study of Integral Variable Structure Control Method for Stability of SI Engine Idling Speed  [PDF]
Yang Zhang, Nobuo Kurihara
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.38094
Abstract: The intake air control system of a gasoline engine is a typical nonlinear system, and included among the adverse fac-tors that always induce poor idle-speed control stability are dead time and disturbances in the intake air control process. In this paper, to improve the responsiveness when idling with regard to disturbances, a mean-value engine model (MVEM) with dead time was constructed as the control object, and the two servo structures of sliding mode control (SMC) were studied for better idle control performance, especially in transient process of speed change. The simulation results confirmed that under the constraint condition of control input, the robustness of idle speed control that is being subjected to torque disturbances and noise disturbances can be greatly improved by use of the servo structure II.
Is Consumption in the United States and Japan Too Much or Too Little?  [PDF]
Yutaka Kurihara, Kei Tomimura
iBusiness (IB) , 2012, DOI: 10.4236/ib.2012.43029
Abstract: This article reports on the results of an empirical examination of whether consumption in the United States and Japan is too much or too little relative to productivity in these countries (1993-2011). Findings reveal some clear and common characteristics of both countries for the sample period. The most typical one occurred during financial crises around 2008, which is often called the Lehman shock. In both countries, consumers had considerably reduced consumption around that period. The IT boom collapse at the beginning of the 2000s also diminished consumption in the United States. This paper examines impulse responses to trace the effect of a productivity shock to one of the innovations on the current and future value of consumption. Findings indicate that the effect of the shock of productivity on consumption is long both countries
Adaptive Back-Stepping Control of Automotive Electronic Control Throttle  [PDF]
Nobuo Kurihara, Hiroyuki Yamaguchi
Journal of Software Engineering and Applications (JSEA) , 2017, DOI: 10.4236/jsea.2017.101003
Abstract: Back-stepping control (BSC), which is deemed effective for a non-holonomic system, is applied to improving both responsiveness and resolution performance of an electronic control throttle (ECT) used in automotive engines. This paper is characterized by the use of a two-step type BSC in a manner that achieves an improvement in responsiveness with the ETC operated in a fully opened state by adding a derivative term in Step 1 and the improvement in resolution performance with the ETC operated in a minutely opened state by adding an adaptive feature in the form of an integral term using the control deviation in Step 2. This paper presents an ECT control expressed as a second-order system including nonlinearities such as backlash of gear train and static friction in sliding area, a BSC system designed based on Lyapunov stability, and a determination method for control parameters. Also, a two-step type BSC system is formulated using Matlab/Simulink with a physics model as a control object. As a result of simulation analyses, it becomes clear that the BSC system can achieve quicker response because the derivative term works effectively and finer resolution because the adaptive control absorbs the error margin of the nonlinear compensation than conventional PID control.
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