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Search Results: 1 - 10 of 1780 matches for " Koji Tamai "
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Comparison of Discharge Duration Curves from Two Adjacent Forested Catchments—Effect of Forest Age and Dominant Tree Species  [PDF]
Koji Tamai
Journal of Water Resource and Protection (JWARP) , 2010, DOI: 10.4236/jwarp.2010.28086
Abstract: The effects of forest age and dominant tree species on the water discharge volume have been analyzed by a paired-watershed experiment in two adjacent catchments in Tatsunokuchi-yama Experimental Forest, western Japan. The control period is 1937-1943. The treated periods are 1948-1953, 1968-1977, and 1996-2003. In these treated periods, the forest age or the dominant tree species were different between two adjacent periods. Differences in the discharge duration curves from the two catchments are compared for the control and the treated periods. A significant change in the discharge duration curves is seen in the third treated period (1996-2003) on days with low water, when the forest age difference between the adjacent catchments was 35 years. This is believed to be the result of differences in forest age and forest treatment just after the occurrence of pine wilt disease.
Evapotranspiration Characteristics of a Lowland Dry Evergreen Forest in Central Cambodia Examined Using a Multilayer Model  [PDF]
Tatsuhiko NOBUHIRO, Akira SHIMIZU, Katsunori TANAKA, Koji TAMAI, Naoki KABEYA, Eriko ITO, Takanori SHIMIZU, Makoto ARAKI, Sophal CHANN
Journal of Water Resource and Protection (JWARP) , 2009, DOI: 10.4236/jwarp.2009.15039
Abstract: Development pressure has led to serious deforestation on the Indochina Peninsula. Particularly rapid defor-estation has occurred in easily accessible lowland areas, and it is thus important to accumulate knowledge about these forests immediately. We measured evapotranspiration rates for a lowland dry evergreen forest in Kampong Thom Province, central Cambodia, using the energy balance Bowen ratio (EBBR) method based on meteorological data collected from a 60-m-high observation tower. Daily evapotranspiration was higher during the dry season than during the rainy season of the Asian monsoon climate. The seasonal variation in evapotranspiration generally corresponded to the seasonal difference in the vapor pressure deficit. A multi-layer model was used to simulate the seasonal variation in evapotranspiration. The multilayer model also reproduced the larger evapotranspiration rate in the dry season than in the rainy season. However, observed values substantially exceeded model-calculated results during certain periods at the beginning of the dry season and in the late dry season. Moreover, during the rainy season, the model tended to overestimate evapotranspiration. The differences between these observed and simulated values may have been caused by seasonal characteristics of photosynthesis and transpiration in the lowland dry evergreen forest that were not considered in the model simulation.
On the Dynamic Role of Monopolistic Competition in the Monetary Economy  [PDF]
Masayuki Otaki, Yoshihiro Tamai
Theoretical Economics Letters (TEL) , 2011, DOI: 10.4236/tel.2011.13024
Abstract: Much static research on the new Keynesian economics is based on the distortion caused by monopolistic pricing. When the theory of monopolistic competition is extended to monetary dynamics in an overlapping generations (OLG) model (Otaki 2007, 2009), the underemployment problem is resolved by a proper monetary policy. However, even in the full-employment equilibrium, the market mechanism does not attain the socially optimal allocation. Since the rate of population growth is assumed to be zero, the optimal gross in- flation rate in the model is unity. There is no such coordination motive in a monetary economy, and hence, the inflation rate may exceed unity. The monopolistic power lowers the inflation rate. The prices of the cur- rent goods relative to the future goods increase by virtue of the monopolistic power. This improves the life- time utility because the lowered inflation rate corrects the consumption stream, which is biased toward the current goods.
A Microeconomic Foundation for the Phillips Curve under Complete Markets without any Exogenous Price Stickiness: A Keynesian View  [PDF]
Masayuki Otaki, Yoshihiro Tamai
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.25090
Abstract: Assuming that labor productivity varies with the previous employment level, we derive the Phillips curve based on the standard dynamic microeconomic foundation. The usage of the term standard implies that our theory entirely excludes assumptions unfamiliar to microeconomics such as price or information stickiness, and money in the utility function. We find that when labor productivity decreases, disinflation advances. This is because disinflation, ceteris paribus, limits the current goods supply and increases the rate of return on money (the inverse of the inflation rate) in an overlapping generations (OLG) model. In addition, mass unemployment becomes a hazard for the intergenerational skill transformation, and thus, the higher the unemployment is, the lower the labor productivity becomes in the stationary state. Consequently, the negative correlation between inflation and unemployment emerges even in the dynamic general equilibrium in complete markets. It is also noteworthy that we depend neither on linear approximations nor on numerical methods: the method used to derive the Phillips curve is purely analytical.
Indications for free vascularized fibular grafting for the treatment of osteonecrosis of the femoral head
Kenji Kawate, Hiroshi Yajima, Kazuya Sugimoto, Hiroshi Ono, Tetsuji Ohmura, Yasunori Kobata, Keiichi Murata, Koji Shigematsu, Kenji Kawamura, Ikuo Kawahara, Naoki Maegawa, Katsuya Tamai, Yoshinori Takakura, Susumu Tamai
BMC Musculoskeletal Disorders , 2007, DOI: 10.1186/1471-2474-8-78
Abstract: Seventy-one hips (60 patients) were clinically followed for a minimum of 3 years. Average follow-up period was 7 years. Etiologies were alcohol abuse in 31 hips, steroid use in 27, idiopathic in 7 and trauma in 6. Preoperative staging of the necrotic lesion was done using the Steinberg's classification system. The outcomes of free vascularized fibular grafting were determined clinically using the Harris hip-scoring system, radiographically by determining progression, and survivorship by lack of conversion to total hip replacement.The average preoperative Harris hip score was 56 points and the average score at the latest follow-up examination was 78 points. Forty-seven hips (67%) were clinically rated good to excellent, 4 hips (6%) were rated fair, and 20 hips (28%) were rated poor. Thirty-six hips (51%) did not show radiographic progression while 35 hips (49%) did, and with an overall survivorship of 83% at 7 years. Steroid-induced osteonecrosis was significantly associated with poor scores and survival rate (68%). Preoperative collapse was significantly associated with poor scores, radiographic progression and poor survival rate (72%). A large extent of osteonecrosis greater than 300 degrees was significantly associated with poor scores, radiographic progression and poor survival rate (67%). There was no relationship between the distance from the tip of the grafted fibula to the subchondral bone of the femoral head and postoperative radiographic progression.In conclusion, small osteonecrosis (less than 300 degrees of the femoral head) without preoperative collapse (Steinberg's stages I and II) is the major indication for free vascularized fibular grafting. Steroid-induced osteonecrosis is a relative contraindication. Large osteonecrosis (greater than 300 degrees) with severe preoperative collapse (greater than 3 mm) is a major contraindication. Hips with 2 negative factors such as severe preoperative collapse and a large extent of osteonecrosis, require hip replace
Plasma L-Cystine/L-Glutamate Imbalance Increases Tumor Necrosis Factor-Alpha from CD14+ Circulating Monocytes in Patients with Advanced Cirrhosis
Eiji Kakazu, Yoshiyuki Ueno, Yasuteru Kondo, Jun Inoue, Masashi Ninomiya, Osamu Kimura, Yuta Wakui, Koji Fukushima, Keiichi Tamai, Tooru Shimosegawa
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023402
Abstract: Background and Aims The innate immune cells can not normally respond to the pathogen in patients with decompensated cirrhosis. Previous studies reported that antigen-presenting cells take up L-Cystine (L-Cys) and secrete substantial amounts of L-Glutamate (L-Glu) via the transport system Xc- (4F2hc+xCT), and that this exchange influences the immune responses. The aim of this study is to investigate the influence of the plasma L-Cys/L-Glu imbalance observed in patients with advanced cirrhosis on the function of circulating monocytes. Methods We used a serum-free culture medium consistent with the average concentrations of plasma amino acids from patients with advanced cirrhosis (ACM), and examined the function of CD14+ monocytes or THP-1 under ACM that contained 0–300 nmol/mL L-Cys with LPS. In patients with advanced cirrhosis, we actually determined the TNF-alpha and xCT mRNA of monocytes, and evaluated the correlation between the plasma L-Cys/L-Glu ratio and TNF-alpha. Results The addition of L-Cys significantly increased the production of TNF alpha from monocytes under ACM. Monocytes with LPS and THP-1 expressed xCT and a high level of extracellular L-Cys enhanced L-Cys/L-Glu antiport, and the intracellular GSH/GSSG ratio was decreased. The L-Cys transport was inhibited by excess L-Glu. In patients with advanced cirrhosis (n = 19), the TNF-alpha and xCT mRNA of monocytes were increased according to the Child-Pugh grade. The TNF-alpha mRNA of monocytes was significantly higher in the high L-Cys/L-Glu ratio group than in the low ratio group, and the plasma TNF-alpha was significantly correlated with the L-Cys/L-Glu ratio. Conclusions A plasma L-Cys/L-Glu imbalance, which appears in patients with advanced cirrhosis, increased the TNF-alpha from circulating monocytes via increasing the intracellular oxidative stress. These results may reflect the immune abnormality that appears in patients with decompensated cirrhosis.
Corrigendum to "Effects of environmental factors and soil properties on topographic variations of soil respiration" published in Biogeosciences, 7, 1133–1142, 2010
K. Tamai
Biogeosciences (BG) & Discussions (BGD) , 2010,
Abstract: No abstract available.
Effects of environmental factors and soil properties on topographic variations of soil respiration
K. Tamai
Biogeosciences (BG) & Discussions (BGD) , 2010,
Abstract: Soil respiration rates were measured along different parts of a slope in (a) an evergreen forest with common brown forest soil and (b) a deciduous forest with immature soil. The effects of soil temperature, soil moisture and soil properties were estimated individually, and the magnitudes of these effects in the deciduous and evergreen forests were compared. In the evergreen forest with common brown forest soil, soil properties had the greatest effect on soil respiration rates, followed by soil moisture and soil temperature. These results may be explained by the fact that different soil properties matured within different environments. It can be argued that the low soil respiration rates in the low parts of the slope in the evergreen forest resulted from soil properties and not from wet soil conditions. In the deciduous forest, soil respiration rates were more strongly affected by soil moisture and soil temperature than by soil properties. These effects were likely due to the immaturity of the forest soil.
Effects of environmental factors and soil properties on topographic variations of soil respiration
K. Tamai
Biogeosciences Discussions , 2009,
Abstract: Soil respiration rates were measured along different parts of a slope in (a) an evergreen forest with mature soil and (b) a deciduous forest with immature soil. The effects of soil temperature, soil moisture, and soil properties on soil respiration rates were estimated individually, and the magnitudes of these effects were compared between the deciduous and evergreen forests. In the evergreen forest with mature soil, soil properties had the greatest effect on soil respiration rates, followed by soil moisture and soil temperature. These results may be explained by different properties of soils that matured under different environments. Thus, we argue that the low soil respiration rates in Plot L of the evergreen forest resulted from soil properties and not from wet soil conditions. In the deciduous forest, soil respiration rates were more strongly affected by soil moisture and soil temperature than by soil properties, which were likely due to the immaturity of the forest soil.
Diagnosis of occult fractures of the ischiopubic rami  [PDF]
Koji Suzuki
Journal of Biomedical Science and Engineering (JBiSE) , 2013, DOI: 10.4236/jbise.2013.63A049
Abstract:
Introduction: Recently, the diagnosis of occult frac- tures has been facilitated due to increased availability and utilization of MRI. Diagnosing a fracture of the ischiopubic rami from a proximal femoral fracture, in particular, is difficult using physical exam alone and can be facilitated by having access to an MRI. Here we report both physical exam findings and MRI findings that help in differentiating occult fractures of the iliopubic rami. Materials and Methods: From April 2010 to December 2012, we identified 30 pa- tients (5 male and 25 female; aged 43 - 93 years old). We recorded if a traumatic episode occurred, ambu- latory status at the initial visit (bed ridden, standing up with an aid, walking with an aid). We also re- corded if imaging was used in determining the final diagnosis (radiographs, MRI or CT). Results: Twenty- one patients had a fracture as a result of a traumatic episode. In the remaining 9 cases, no trauma oc- curred and therefore the fractures were insufficiency fractures. Ten patients were bed ridden at the initial visit, eight patients were able to stand only with a walking aid, and the remaining twelve patients were able to walk with an aid. Occasional radiographs were used to confirm the presence of a fracture in 4 cases, MRI in 11 cases, and CT scan in 15 cases. Dis- cussion and Conclusions: Occult fractures of the is- chiopubic rami can occur without trauma and it can be difficult to differentiate these fractures from occult proximal femoral fractures. In these cases, MRI is useful to definitively obtain a diagnosis. In cases of pacemaker, bullet implantation or artificial hip joints, CT or occasional radiographs are also useful to diag- nose occult fractures of the ischiopubic rami.
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