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Search Results: 1 - 10 of 1852 matches for " Masahiro Nakamichi "
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Is Galaxy Distribution Non-extensive and Non-Gaussian?
Akika Nakamichi,Masahiro Morikawa
Physics , 2003, DOI: 10.1016/j.physa.2004.04.116
Abstract: Self gravitating systems (SGS) in the Universe are generally thought to be non-extensive, and often show long-tails in various distribution functions. In principle, these non-Boltzmann properties are naturally expected from the peculiar property of gravity, long-range and unshielded. Therefore the ordinary Boltzmann statistical mechanics would not be applicable for these self gravitating systems (SGS) in its naive form. In order to step further, we quantitatively investigate the above two properties, non-extensivity and long-tails, by explicitly introducing various models of statistical mechanics. We use the data of CfA II South redshift survey and apply the count-in-cell method. We study four statistical mechanics, (1) Boltzmann, (2) Fractal, (3) R\'enyi, and (4) Tsallis, and use Akaike information criteria (AIC) for the fair comparison.
Quantum measurement driven by spontaneous symmetry breaking
Masahiro Morikawa,Akika Nakamichi
Physics , 2005, DOI: 10.1143/PTP.116.679
Abstract: The measurement process in quantum mechanics is usually described by the von Neumann projection postulate, which forms a basic constituent of the laws of quantum mechanics. Since this postulate requires the outside observer of the system, it is hard to apply quantum mechanics to the whole Universe. Therefore we propose that the quantum measurement process is actually a physical process associated with the ubiquitous mechanism of spontaneous symmetry breaking. Based on this proposal, we construct a quantum measurement model in which the von Neumann projection is described as the dynamical pro-coherence process. Furthermore, the classically distinguishable pointer parameter emerges as the c-number order parameter in the formalism of closed time-path quantum filed theory. We also discuss the precision of the measurement and the possible deduction of the Born probability postulate.
Late-Time Mild Inflation --- a possible solution of dilemma: cosmic age and the Hubble parameter ---
Takeshi Fukuyama,Mikiko Hatakeyama,Masae Miyoshi,Masahiro Morikawa,Akika Nakamichi
Physics , 1996, DOI: 10.1142/S0218271897000066
Abstract: We explore the cosmological model in which a late-time mild inflation is realized after the star formation epoch. Non-vanishing curvature coupling of a classical boson field yields this mild inflation without a cosmological constant. Accordingly the lifetime of the present Universe is remarkably increased in our model. Thus we show that the present observed high value of the Hubble parameter $H_0 \approx 70-80{\rm km/sec/Mpc}$ is compatible with the age of the oldest stars $14{\rm Gyr}$ without introducing the cosmological constant or the open Universe model. Moreover in our model, the local Hubble parameter becomes larger than the global one. Thus we show that the present observed local Hubble parameter measured by using the Cepheid variables is compatible with the global Hubble parameter measured by using the Sunyaev-Zeldovich effect. We also examine the energy conditions, evolution of the effective gravitational constant and the nucleosynthesis process.
Galaxy Distributions and Tsallis Statistical Mechanics
Akika Nakamichi,Izumi Joichi,Osamu Iguchi,Masahiro Morikawa
Physics , 2000,
Abstract: Large-scale astrophysical systems are non-extensive due to their long-range force of gravity. Here we show an approach toward the statistical mechanics of such self-gravitating systems (SGS). This is a generalization of the standard statistical mechanics based on the new definition of entropy; Tsallis statistical mechanics. Developing the composition of entropy and the generalized Euler relation, we investigate the galaxy distributions in count-in-cell method. This is applied to the data of CfA II South redshift survey.
Dietary γ-Aminobutyric Acid Shortens the Life Span of Stroke-Prone Spontaneously Hypertensive Rats  [PDF]
Nakamichi Watanabe, Naomi Washio
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.24043
Abstract: Dietary γ-amino butyric acid (GABA) has been suggested to decrease systolic blood pressure. This study aimed to ex-amine the effects of dietary GABA on the life span of stroke-prone spontaneously hypertensive rats (SHRSPs). In this study, life span was determined for SHRSPs provided 1% NaCl solution or 0.01% GABA in 1% NaCl solution as drinking water. The life span of the GABA-fed group (76.3 ± 1.65 days) was significantly shorter than that of the control group (81.6 ± 0.88 days). The results of this study may not be applicable to humans. Future studies will be necessary to elucidate the mechanism underlying this phenomenon.
Effects of Dietary Citric Acid on Metabolic Indicators and Gene Expression in the Skeletal Muscles of Fasted Mice  [PDF]
Yurie Hara, Nakamichi Watanabe
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.411145

Citric acid is recognized and utilized as a dietary supplement for its ability to eliminate fatigue. However, the molecular and cellular mechanism underlying this effect has not been elucidated. This study investigated the effect of intragastric citric acid administration on the energy metabolism and gene expression in the skeletal muscles of mice that had been fasted without exercise, using biochemical analyses of metabolic indicators and DNA microarrays. Expression of the genes involved in the glycolysis, tricarboxylic acid cycle and β-oxidation of fatty acids were not affected by citric acid administration. However, citric acid increased the level of blood glucose and expression of the phosphoenolpyruvate carboxykinase gene. These results indicate that citric acid ingestion may eliminate fatigue by promoting gluconeogenesis.

Fatigue Alleviation Mechanism of Citric Acid Determined by Gene Expression Analysis in the Mouse Liver  [PDF]
Yurie Hara, Nakamichi Watanabe
Food and Nutrition Sciences (FNS) , 2015, DOI: 10.4236/fns.2015.612114
Abstract: Citric acid has been recognized for its ability to alleviate fatigue; however, the mechanism contributing to this effect has not yet been elucidated. Our previous study suggested that the alleviation of fatigue by citric acid intake might be induced by the acceleration of gluconeogenesis. In this study, we tested this hypothesis and evaluated whether the intake of citric acid accelerates gluconeogenesis in the mouse liver through microarray analysis. Because the microarray of focus includes 200 metabolic genes, it could be used to provide information on genes related to glucose metabolism as well as other pathways such as inflammation. Eight-week-old male C57/BL6J mice were divided into the distilled water and citric acid groups (n = 6), and were administered distilled water or a citric acid solution (20 mg/30g body weight) intragastrically with a probe, respectively. Forty minutes after administration, the mice were sacrificed by decapitation. The blood glucose level of the citric acid group was significantly higher (P = 0.001) than that of the distilled water group. The expression levels of genes related to glucose metabolism (Gck, Pfkl, Pklr, Pck1, G6pc) were not changed by the intake of citric acid. On the other hand, some transcriptional differences were observed in several other genes, including those related to inflammation, blood pressure, the electron transport system, uncoupling proteins, and anti-oxidation. The expression levels of genes related to inflammation were reduced in the citric acid group; e.g., the Il6 expression level was 0.78 times lower in the citric acid group than that in the distilled water group. In conclusion, the results of this study suggest that citric acid intake could accelerate gluconeogenesis and suppresses inflammation. Therefore, the fatigue-alleviation effects of citric acid might be induced by an additive effect between the maintenance of blood glucose levels and the suppression of inflammation.
Expression of Genes Related to Glycolysis in the Liver and Skeletal Muscle of Rats after Citric Acid Administration  [PDF]
Yurie Hara, Nakamichi Watanabe
Food and Nutrition Sciences (FNS) , 2019, DOI: 10.4236/fns.2019.103025
Abstract: Citric acid is known to alleviate physical fatigue and improve athletic performance; however, the underlying mechanism is unknown. Therefore, we aimed to investigate the effect of citric acid administration on the expression of key glycolysis-related genes in the liver and skeletal muscle of rats. Eight-week-old male Sprague-Dawley rats were divided into two groups—control and citric acid groups. The rats were fasted overnight, after which distilled water or citric acid solution was administered intragastrically; after 150 min, the rats were sacrificed, and the liver and skeletal muscle were collected. In the skeletal muscle, namely soleus and gastrocnemius muscles, the phosphofructokinase and pyruvate kinase gene expression were significantly decreased by citric acid administration. In contrast, the glucokinase and pyruvate kinase gene expression in the liver was significantly increased. These results suggest that exogenous dietary citric acid suppresses glycolysis in the skeletal muscle at the transcription level.
Proteomic Analysis of Growth Phase-Dependent Expression of Legionella pneumophila Proteins Which Involves Regulation of Bacterial Virulence Traits
Tsuyoshi Hayashi,Masahiro Nakamichi,Hirotaka Naitou,Norio Ohashi,Yasuyuki Imai,Masaki Miyake
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011718
Abstract: Legionella pneumophila, which is a causative pathogen of Legionnaires' disease, expresses its virulent traits in response to growth conditions. In particular, it is known to become virulent at a post-exponential phase in vitro culture. In this study, we performed a proteomic analysis of differences in expression between the exponential phase and post-exponential phase to identify candidates associated with L. pneumophila virulence using 2-Dimentional Fluorescence Difference Gel Electrophoresis (2D-DIGE) combined with Matrix-Assisted Laser Desorption/Ionization–Mass Spectrometry (MALDI-TOF-MS). Of 68 identified proteins that significantly differed in expression between the two growth phases, 64 were up-regulated at a post-exponential phase. The up-regulated proteins included enzymes related to glycolysis, ketone body biogenesis and poly-3-hydroxybutyrate (PHB) biogenesis, suggesting that L. pneumophila may utilize sugars and lipids as energy sources, when amino acids become scarce. Proteins related to motility (flagella components and twitching motility-associated proteins) were also up-regulated, predicting that they enhance infectivity of the bacteria in host cells under certain conditions. Furthermore, 9 up-regulated proteins of unknown function were found. Two of them were identified as novel bacterial factors associated with hemolysis of sheep red blood cells (SRBCs). Another 2 were found to be translocated into macrophages via the Icm/Dot type IV secretion apparatus as effector candidates in a reporter assay with Bordetella pertussis adenylate cyclase. The study will be helpful for virulent analysis of L. pneumophila from the viewpoint of physiological or metabolic modulation dependent on growth phase.
Statistical Mechanics of Self--Gravitating System : Cluster Expansion Method
Osamu Iguchi,Tomomi Kurokawa,Masahiro Morikawa,Akika Nakamichi,Yasuhide Sota,Takayuki Tatekawa,Kei--ichi Maeda
Physics , 1998, DOI: 10.1016/S0375-9601(99)00422-3
Abstract: We study statistical mechanics of the self--gravitating system applying the cluster expansion method developed in solid state physics. By summing infinite series of diagrams, we derive a complex free energy whose imaginary part is related to the relaxation time of the system. Summation of another series yields two--point correlation function whose correlation length is essentially given by the Jeans wavelength of the system.
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