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Search Results: 1 - 10 of 685 matches for " Daiju Fukuda "
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Phase Transition to Insulating State from Quantum Hall State by Current-Induced Nuclear Spin Polarization
Shibun Tsuda,Minh-Hai Nguyen,Daiju Terasawa,Akira Fukuda,Anju Sawada
Physics , 2013,
Abstract: We investigate the resistance enhancement state (RES) where the magnetoresistance of the $\nu = 2/3$ fractional quantum Hall state (FQHS) is increased with dynamic nuclear spin polarization (DNP) induced by a large electric current. After inducing DNP, we measure the temperature dependence of the magnetoresistance by a small current over a short period of time. We find that the FQHS makes a phase transition to an insulating state. By measuring the Hall resistance in the insulating state, we find that the RES exhibits a quantized Hall resistance. We discuss the RES in association with the Anderson localization.
Interlayer Diffusion of Nuclear Spin Polarization in $ν=2/3$ Quantum Hall States
Minh-Hai Nguyen,Shibun Tsuda,Daiju Terasawa,Akira Fukuda,Yangdong Zheng,Anju Sawada
Physics , 2013, DOI: 10.1103/PhysRevB.89.041403
Abstract: At the spin transition point of $\nu=2/3$ quantum Hall states, nuclear spins in a two-dimensional electron gas are polarized by an electric current. Using GaAs/AlGaAs double-quantum-well samples, we first observed the spatial diffusion of nuclear spin polarization between the two layers when the nuclear spin polarization is current-induced in one layer. By numerical simulation, we estimated the diffusion constant of the nuclear spin polarization to be $15 \pm 7$\,nm$^2$/s.
Telmisartan ameliorates insulin sensitivity by activating the AMPK/SIRT1 pathway in skeletal muscle of obese db/db mice
Asuka Shiota, Michio Shimabukuro, Daiju Fukuda, Takeshi Soeki, Hiromi Sato, Etsuko Uematsu, Yoichiro Hirata, Hirotsugu Kurobe, Norikazu Maeda, Hiroshi Sakaue, Hiroaki Masuzaki, Iichiro Shimomura, Masataka Sata
Cardiovascular Diabetology , 2012, DOI: 10.1186/1475-2840-11-139
Abstract: Nine-week-old male db/db mice were fed a 60% high-fat diet, with orally administrated either vehicle (carboxymethyl-cellulose, CMC), 5 mg/kg telmisartan, or 5 mg/kg telmisartan and 1 mg/kg GW9662, a selective irreversible antagonist of PPARγ, for 5 weeks. Effects of telmisartan on Sirt1 mRNA, AMPK phosphorylation, and NAD+/NADH ratio were determined in C2C12 cultured myocytes.Telmisartan treatment improved insulin sensitivity in obese db/db mice fed a high-fat diet and led to reduction in the size of hypertrophic pancreatic islets in these mice. Moreover, in vitro treatment with telmisartan led to increased expression of Sirt1 mRNA in C2C12 skeletal muscle cells; the increase in Sirt1 mRNA in telmisartan-treated C2C12 myoblasts occurred concomitantly with an increase in AMPK phosphorylation, an increase in NAD+/NADH ratio, and increases in the mRNA levels of PGC1α, FATP1, ACO, and GLUT4.Our results indicate that telmisartan acts through a PPARγ-independent pathway, but at least partially exerts its effects by acting directly on skeletal muscle AMPK/SIRT1 pathways.The nicotinamide adenine dinucleotide (NAD)-dependent deacetylase (SIRT1) has been reported to be involved in protection against metabolic disorders as well as in enhancing life span [1]. Evidence suggests that SIRT1 also plays a fundamental role in the metabolism and differentiation of skeletal muscle cells [2], and transgenic or knockout Sirt1 mouse models have implicated the protein in protection of skeletal muscle against oxidative stress [3,4]. It has been speculated that SIRT1 plays an important role in the regulation of transcriptional networks in various critical metabolic processes [1]. The SIRT1 signal seems to be mediated by an increase in fatty acid oxidation by activation of AMP-activated protein kinase (AMPK) in skeletal muscle [5]. The AMPK activators metformin [6] and A-769662 [7], as well as resveratrol [8], a polyphenolic SIRT1 activator, ameliorate insulin resistance in animals given a hi
The Effects of Opening Trade on Regional Inequality in a Model of Scale-Invariant Growth and Foot-Loose Capital  [PDF]
Katsufumi Fukuda
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.25078
Abstract: We consider a semi endogenous R & D growth model with international trade, foot-loose capital, and local and international knowledge spillovers in a closed economy and also international knowledge spillovers in an open economy. We show that by opening trade two regions diverge (converge) with (not) sufficiently high intertemporal knowledge spillover in the R & D sector and elasticity of substitution between modern goods, and not sufficiently high (sufficiently high) richer country A’s share of firm owned.
Collisionless Damping of Low-Frequency Magnetosonic Pulses in a Two-Ion-Species Plasma
Mieko Toida,Daiju Dogen,Yukiharu Ohsawa
Physics , 1999, DOI: 10.1143/JPSJ.68.2157
Abstract: Low-frequency mangnetosonic pulses in a two-ion-species plasma are studied theoretically and by simulation with a one-dimensional electromagnetic simulation code based on a three-fluid model, with particular attention to the dynamics of minority heavy ions. It is found that heavy ions can gain some energy from the pulses. Because of this energy transfer, the pulses are damped even if the plasma is collisionless and pulse propagation is perpendicular to the magnetic field.
Protocol-dependent shear modulus of amorphous solids
Daiju Nakayama,Hajime Yoshino,Francesco Zamponi
Physics , 2015,
Abstract: We investigate the linear elastic response of amorphous solids to a shear strain at zero temperature. We find that the response is characterized by at least two distinct shear moduli. The first one, $\mu_{\rm ZFC}$, is associated with the linear response of a single energy minimum. The second, $\mu_{\rm FC}$, is related to sampling, through plastic events, an ensemble of distinct energy minima. We provide examples of protocols that allow one to measure both shear moduli. In agreement with a theoretical prediction based on the exact solution in infinite spatial dimensions, the ratio $\mu_{\rm FC}/\mu_{\rm ZFC}$ is found to vanish proportionally to the square root of pressure at the jamming transition. Our results establish that amorphous solids are characterized by a rugged energy landscape, on which the infinite-dimensional solution can give useful insight.
Gender disparities in the association between epicardial adipose tissue volume and coronary atherosclerosis: A 3-dimensional cardiac computed tomography imaging study in Japanese subjects
Munkhbaatar Dagvasumberel, Michio Shimabukuro, Takeshi Nishiuchi, Junji Ueno, Shoichiro Takao, Daiju Fukuda, Yoichiro Hirata, Hirotsugu Kurobe, Takeshi Soeki, Takashi Iwase, Kenya Kusunose, Toshiyuki Niki, Koji Yamaguchi, Yoshio Taketani, Shusuke Yagi, Noriko Tomita, Hirotsugu Yamada, Tetsuzo Wakatsuki, Masafumi Harada, Tetsuya Kitagawa, Masataka Sata
Cardiovascular Diabetology , 2012, DOI: 10.1186/1475-2840-11-106
Abstract: The study population consisted of 90 consecutive subjects (age: 63 ± 12 years; men: 47, women: 43) who underwent 256-slice multi-detector computed tomography (MDCT) coronary angiography. EATV was measured as the sum of cross-sectional epicardial fat area on CT images, from the lower surface of the left pulmonary artery origin to the apex. Subjects were segregated into the CAD group (coronary luminal narrowing > 50%) and non-CAD group.EATV/body surface area (BSA) was higher among men in the CAD group than in the non-CAD group (62 ± 13 vs. 33 ± 10 cm3/m2, p < 0.0001), but did not differ significantly among women in the 2 groups (49 ± 18 vs. 42 ± 9 cm3/m2, not significant). Multivariate logistic analysis showed that EATV/BSA was the single predictor for >50% coronary luminal narrowing in men (p < 0.0001). Predictors excluded were age, body mass index, hypertension, diabetes mellitus, and hyperlipidemia.Increased EATV is strongly associated with coronary atherosclerosis in men.Epicardial adipose tissue (EAT) is the visceral fat located between the outer layer of the myocardium and the visceral pericardium [1-4]. EAT volume (EATV) is correlated with various cardiovascular risk factors, independent of abdominal visceral adiposity, body mass index (BMI), hypertension, and diabetes mellitus [5-7]. Two population-based studies, the Multi-Ethnic Study of Atherosclerosis and the Framingham Heart Study, showed that EATV is an independent risk predictor for cardiovascular disease [5,8,9]. EAT is shown to be metabolically active and the source of pro-atherogenic mediators and adipocytokines [1-5]. Because EAT and the myocardium are located close anatomically, it is predicted that cytokines/adipocytokines produced by infiltrated macrophages or by adipocytes could locally modulate myocardial function or contribute to the pathogenesis of coronary atherosclerosis [1-5]. Recently, we [10,11] and others [12] showed that proinflammatory cytokines and adipocytokines are expressed and sec
Heterostructure Solar Cells Based on Sol-Gel Deposited SnO2 and Electrochemically Deposited Cu2O  [PDF]
Akito Fukuda, Masaya Ichimura
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.46A001
Abstract:

To fabricate a heterostructure solar cell using environmentally friendly materials and low cost techniques, tin oxide (SnO2) and cuprous oxide (Cu2O) were deposited by the sol-gel method and the electrochemical deposition, respectively. The SnO2 films were deposited from a SnCl2 solution containing ethanol and acetic acid. The Cu2O films were deposited using a galvanostatic method from an aqueous bath containing CuSO4 and lactic acid at a temperature of 40°C. The Cu2O/SnO2 heterostructure solar cells showed rectification and photovoltaic properties, and the best cell showed a conversion efficiency of 6.6 × 10-2 % with an open-circuit voltage of 0.29 V, a short-circuit current of 0.58 mA/cm2, and a fill factor of 0.39.

On numerically effective log canonical divisors
Shigetaka Fukuda
International Journal of Mathematics and Mathematical Sciences , 2002, DOI: 10.1155/s0161171202012450
Abstract: Let (X,Δ) be a 4-dimensional log variety which is proper over the field of complex numbers and with only divisorial log terminal singularities. The log canonical divisor KX
Financial Development, Economic Growth and Financial Crisis in Asian Emerging Economies
Takashi Fukuda
Research in Applied Economics , 2012, DOI: 10.5296/rae.v4i2.1429
Abstract: This article examines the causality between financial development, economic growth and financial crisis in India, Indonesia, Korea, Malaysia and Thailand; all these countries are known as emerging economies with well known financial crisis episodes. The summary indicators of financial development, financial crisis and financial repression are created through the principal component method. The cointegration and Granger causality are investigated by using two techniques of vector error correction model (VECM) and autoregressive distributed lag (ARDL). The main findings are: (1) the direction of the finance-growth nexus is a country-specific matter; (2) deeper financial development can lead to financial crisis; and (3) financial crisis has a negative impact on economic growth (except Korea for the last two).
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