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Search Results: 1 - 10 of 1017 matches for " Toshiyuki Kitazawa "
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A Method for Determining Batillaria attramentaria Distribution Using Aerial Balloon Photography and a Vegetation Index Camera: Demonstration at the Yatsu Tidal Flat, Chiba Prefecture  [PDF]
Yohei Shiraki, Toshiyuki Kitazawa, Seongwon Lee, Yukiko Senga
Advances in Remote Sensing (ARS) , 2018, DOI: 10.4236/ars.2018.71002
Abstract: Located in Chiba Prefecture, the Yatsu Tidal Flat is an important stopover for birds migrating between cold regions such as Siberia and warm regions such as Southeast Asia and Australia. Its importance led to its selection in 1993 as the first tidal flat in Japan to be registered under the Convention on Wetlands of International Importance especially as Waterfowl Habitat (the Ramsar Convention). However, the Yatsu Tidal Flat has in more recent years witnessed blooms of Ulva spp. (sea lettuce) and an increase in exotic species such as Batillaria attramentaria (Japanese mud snail) and Mercenaria mercenaria (hard clam), fueling concerns that the increasing spatial domination of the tidal flat by such species and competition with other species for food may drive a decline in the habitat’s self-cleaning capabilities. For this study, we focused on Batillaria attramentaria, which is now so widely distributed in the Yatsu Tidal Flat as to preclude reliable monitoring via aerial photographs or satellite imagery. Accordingly, we tested the utility of a simplified method for obtaining data on the distribution of Batillaria attramentaria by using aerial balloon photography and a vegetation index camera capable of generating NDVI data. Our results show that under certain conditions, this method can indeed be used to determine Batillaria attramentaria distribution.
Hyperbolic Transformation and Average Elasticity in the Framework of the Fixed Effects Logit Model  [PDF]
Yoshitsugu Kitazawa
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.22034
Abstract: In this paper, a simple transformation is proposed for the fixed effects logit model, which constructs some valid moment conditions including the first-order condition for one of the conditional MLE proposed by Chamberlain (1980) [1]. Some Monte Carlo experiments are carried out for the GMM estimator based on the transformation. In addition, the average elasticity of the logit probability with respect to the exponential function of explanatory variable is proposed in the framework of the fixed effects logit model, which is computable without the fixed effects.
Some Additional Moment Conditions for a Dynamic Count Panel Data Model with Predetermined Explanatory Variables  [PDF]
Yoshitsugu Kitazawa
Open Journal of Statistics (OJS) , 2013, DOI: 10.4236/ojs.2013.35038

This paper proposes some additional moment conditions for the linear feedback model with explanatory variables being predetermined, which is proposed by [1] for the purpose of dealing with count panel data. The newly proposed moment conditions include those associated with the equidispersion, the Negbin I-type model and the stationarity. The GMM estimators are constructed incorporating the additional moment conditions. Some Monte Carlo experiments indicate that the GMM estimators incorporating the additional moment conditions perform well, compared to that using only the conventional moment conditions proposed by [2,3].

Innate immune reactivity of the liver in rats fed a choline-deficient L-amino-acid-defined diet
Hideto Kawaratani, Tatsuhiro Tsujimoto, Toshiyuki Kitazawa, Mitsuteru Kitade, Hitoshi Yoshiji, Masahito Uemura, Hiroshi Fukui
World Journal of Gastroenterology , 2008,
Abstract: AIM: To investigate the innate immune reactivity of tumor necrosis factor-alpha (TNF-α), Toll-like receptor 4 (TLR4), and CD14 in the liver of non-alcoholic steatohepatitis (NASH) model rats.METHODS: Male F344 rats were fed a choline-deficient L-amino-acid-defined (CDAA) diet. The rats were killed after 4 or 8 wk of the diet, and their livers were removed for immunohistochemical investigation and RNA extraction. The liver specimens were immunostained for TNF-α, TLR4, and CD14. The gene expressions of TNF-α, TLR4, and CD14 were determined by reverse-transcriptase polymerase chain reaction (RT-PCR). Kupffer cells were isolated from the liver by Percoll gradient centrifugation, and were then cultured to measure TNF-α production.RESULTS: The serum and liver levels of TNF-α in the CDAA-fed rats increased significantly as compared with the control group, as did the immunohistochemical values and gene expressions of TNF-α, TLR4, and CD14 with the progression of steatohepatitis. TNF-α production from the isolated Kupffer cells of the CDAA-fed rats was elevated by lipopolysaccharide stimulation.CONCLUSION: The expressions of TNF-α, TLR4, and CD14 increased in the NASH model, suggesting that TLR4 and CD14-mediated endotoxin liver damage may also occur in NASH.
Immunotherapy for nonalcoholic steatohepatitis using the multiple cytokine production modulator Y-40138
Tatsuhiro Tsujimoto, Hideto Kawaratani, Toshiyuki Kitazawa, Hitoshi Yoshiji, Masao Fujimoto, Masahito Uemura, Hiroshi Fukui
World Journal of Gastroenterology , 2009,
Abstract: AIM: To investigate the possible use of the multiple cytokine production modulator, Y-40138, as a novel immunotherapy in the rat nonalcoholic steatohepatitis (NASH) model.METHODS: We allocated 6-wk-old male F344 rats to choline-supplemented, L-amino acid-defined (CSAA) diet (control group), CSAA diet + Y-40138 (control + Y-40138 group), choline-deficient, L-amino acid-defined (CDAA) diet (NASH group), or CDAA diet + Y-40138 (NASH + Y-40138 group). In each group, we measured the plasma alanine aminotransferase (ALT) levels, and the plasma and liver levels of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukin-10 (IL-10). Tissue specimens of phosphate buffered saline-perfused liver were subjected to hematoxylin and eosin staining, Azan staining, Sirius red staining, and immunohistochemical staining (for Kupffer cells and TNF-α). We then extracted Kupffer cells from the collagenase-perfused livers using the Percoll gradient centrifugation method, and measured the TNF-α levels in the supernatant (in vitro TNF-α production by Kupffer cells) using an enzyme-linked immunosorbent assay kit.RESULTS: In comparison to the NASH group, serum ALT elevation was mild, production of serum and liver TNF-α and IFN-γ was inhibited, and IL-10 production was increased in the NASH + Y-40138 group. Amelioration of liver histology was also noted in the NASH + Y-40138 group. Kupffer cell immunohistochemical staining revealed no differences between groups, whereas TNF-α immunohistochemical staining showed fewer stained cells in the NASH + Y-40138 group than in the NASH group. The TNF-α levels in the in-vitro Kupffer cell culture supernatant were lower in the NASH + Y-40138 group than in the NASH group.CONCLUSION: Administration of Y-40138 to NASH model rats reduced hepatic inflammation and suppressed fibrosis. These results indicate that the multiple cytokine production modulator, Y-40138, is promising as a novel treatment for NASH.
Superconducting anisotropy and evidence for intrinsic pinning in single crystalline MgB$_2$
Ken'ichi Takahashi,Toshiyuki Atsumi,Nariaki Yamamoto,Mingxiang Xu,Hideaki Kitazawa,Takekazu Ishida
Physics , 2002, DOI: 10.1103/PhysRevB.66.012501
Abstract: We examine the superconducting anisotropy $\gamma_c = (m_c / m_{ab})^{1/2}$ of a metallic high-$T_c$ superconductor MgB$_2$ by measuring the magnetic torque of a single crystal. The anisotropy $\gamma_c$ does not depend sensitively on the applied magnetic field at 10 K. We obtain the anisotropy parameter $\gamma_c = 4.31 \pm 0.14$. The torque curve shows the sharp hysteresis peak when the field is applied parallel to the boron layers. This comes from the intrinsic pinning and is experimental evidence for the occurrence of superconductivity in the boron layers.
Characteristics of Unsteady Boundary Layer Induced by the Compression Wave Propagating in a Tunnel  [PDF]
Toshiyuki Tanaka, Toshiyuki Aoki
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.24A030

A compression wave is generated ahead of a high-speed train, while entering a tunnel. This compression wave propa- gates to the tunnel exit and spouts out as a micro pressure wave, causing an exploding sound. In order to estimate the magnitude correctly, the mechanism of the attenuation and distortion of a compression wave propagating along a tunnel must be understood and experimental information on these phenomena is required. An experimental and numerical in- vestigation is carried out to clarify the mechanism of the propagating compression wave in a tube. The final objective of our study is to understand the mechanism of the attenuation and distortion of propagating compression waves in a tun- nel. In the present paper, experimental investigations are carried out on the transition of the unsteady boundary layer induced by a propagating compression wave in a model tunnel by means of a developed laser differential interferometry technique.

Decreased phagocytic activity of Kupffer cells in a rat nonalcoholic steatohepatitis model
Tatsuhiro Tsujimoto, Hideto Kawaratani, Toshiyuki Kitazawa, Toshiko Hirai, Hajime Ohishi, Mitsuteru Kitade, Hitoshi Yoshiji, Masahito Uemura, Hiroshi Fukui
World Journal of Gastroenterology , 2008,
Abstract: AIM: To investigate Kupffer cell dynamics and phagocytic activity, using a rat nonalcoholic steatohepatitis (NASH) model.METHODS: Male F344 rats were fed either a control diet or a choline-deficient L-amino acid-defined (CDAA) diet, followed by contrast enhanced ultrasonography (CEUS) using Levovist . The uptake of latex beads by the Kupffer cells was determined by fluorescent microscopy. The status of the Kupffer cells was compared between the two groups, using the immunohistochemical staining technique.RESULTS: After 4 or more wk of the CDAA diet, CEUS examination revealed a decrease in the signal intensity, 20 min after intravenous Levovist . Fluorescent microscopic examination showed that the uptake of latex beads by the Kupffer cells was reduced at week 1 and 2 in the study group, compared with the controls, with no further reduction after 3 wk. Immunohistochemical staining revealed no significant difference in the Kupffer cell counts between the control group and the CDAA group.CONCLUSION: CEUS examination using Levovist demonstrated reduced contrast effect and phagocytic activity in the liver parenchymal phase, although the Kupffer cell numbers were unchanged, indicating reduced phagocytic function of the Kupffer cells in the rat NASH model. We believe that CEUS examination using Levovist is a useful screening modality, which can detect NASH in fatty liver patients.
The Menu-Induced Core of an Economy with an Excludable Public Good  [PDF]
Toshiyuki Hirai
Theoretical Economics Letters (TEL) , 2014, DOI: 10.4236/tel.2014.44039

This paper introduces a core concept in an economy with an excludable public good. In the economy, we assume that each coalition is allowed to achieve an allocation via a menu, a kind of a nonlinear price. Our core concept is called the menu-induced core that is defined as the set of allocations achievable by menus that are robust against all coalitional improvements achieved via menus. We show that the menu-induced core is nonempty. We also investigate certain properties of the menu-induced core that show the difference between the menu-induced core and the core defined in a standard way.

A Review of Measurement-Integrated Simulation of Complex Real Flows  [PDF]
Toshiyuki Hayase
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2015, DOI: 10.4236/jfcmv.2015.32006
Abstract: In spite of the inherent difficulty, reproducing the exact structure of real flows is a critically important issue in many fields, such as weather forecasting or feedback flow control. In order to obtain information on real flows, extensive studies have been carried out on methodology to integrate measurement and simulation, for example, the four-dimensional variational data assimilation method (4D-Var) or the state estimator such as the Kalman filter or the state observer. Measurement-integrated (MI) simulation is a state observer in which a computational fluid dynamics (CFD) scheme is used as a mathematical model of the physical system instead of a small dimensional linear dynamical system usually used in state observers. A large dimensional nonlinear CFD model makes it possible to accurately reproduce real flows for properly designed feedback signals. This review article surveys the theoretical formulations and applications of MI simulation. Formulations of MI simulation are presented, including governing equations of a flow field observer, those of a linearized error dynamics describing the convergence of the observer, and stabilization of the numerical scheme, which is important in implementation of MI simulation. Applications of MI simulation are presented ranging from fundamental turbulent flows in pipes and Karman vortices in a wind tunnel to clinical application in diagnosis of blood flows in a human body.
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