Curvature-induced phase transitions in the inflationary universe - Supersymmetric Nambu-Jona-Lasinio Model in de Sitter spacetime -

The phase structure associated with the chiral symmetry is thoroughly investigated in de Sitter spacetime in the supersymmetric Nambu-Jona-Lasinio model with supersymmetry breaking terms. The argument is given in the three and four space-time dimensions in the leading order of the 1/N expansion and it is shown that the phase characteristics of the chiral symmetry is determined by the curvature of de Sitter spacetime. It is found that the symmetry breaking takes place as the first order as well as second order phase transition depending on the choice of the coupling constant and the parameter associated with the supersymmetry breaking term. The critical curves expressing the phase boundary are obtained. We also discuss the model in the context of the chaotic inflation scenario where topological defects (cosmic strings) develop during the inflation.Comment: 29 pages, 6 figures, REVTe

A Model of Curvature-Induced Phase Transitions in Inflationary Universe

Chiral phase transitions driven by space-time curvature effects are investigated in de Sitter space in the supersymmetric Nambu-Jona-Lasinio model with soft supersymmetry breaking. The model is considered to be suitable for the analysis of possible phase transitions in inflationary universe. It is found that a restoration of the broken chiral symmetry takes place in two patterns for increasing curvature : the first order and second order phase transition respectively depending on initial settings of the four-body interaction parameter and the soft supersymmetry breaking parameter. The critical curves expressing the phase boundaries in these parameters are obtained. Cosmological implications of the result are discussed in connection with bubble formations and the creation of cosmic strings during the inflationary era.Comment: 12 pages, 3 figures, REVTe

New Development of the J -Based Fracture Testing Technique for Ceramic-Matrix Composites

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65733/1/j.1151-2916.1994.tb09756.x.pd

Numerical simulation of non-fickian diffusion and advection in a fractured porous aquifer

A computer program, which enables us the calculation of the non-Fickian diffusion in a fractured porous media, has been developed. The conventional mathematical model of solute transport in a rock is based on the Fick's law. In general, rock masses contain a number of preexisting fractures. In the fractured porous media, the conventional model tends to predict smaller solute travel distance than that in the actual transport process. In contrast, the non-Fickian diffusion model, which is described as a fractional advection-dispersion equation, can provide realistic representation of actual fluid flow in the heterogeneous media. We provide a numerical solution of the fractional advection-dispersion equation by using implicit-finite difference method. The numerical results obtained for one dimensional fractional advection-dispersion equation using the computer program was shown to be in a good agreement with the analytical solution. © 2007 American Institute of Physics

南大洋インド洋区季節海氷域における溶存炭酸物質の季節変化

第6回極域科学シンポジウム分野横断セッション：[IB1] 海氷域における生物地球化学的研究11月17日（火）　統計数理研究所 セミナー室1（D305

Mass Hierarchies and the Seesaw Neutrino Mixing

We give a general analysis of neutrino mixing in the seesaw mechanism with three flavors. Assuming that the Dirac and u-quark mass matrices are similar, we establish simple relations between the neutrino parameters and individual Majorana masses. They are shown to depend rather strongly on the physical neutrino mixing angles. We calculate explicitly the implied Majorana mass hierarchies for parameter sets corresponding to different solutions to the solar neutrino problem.Comment: 11 pages, no figures, replaced with final version. Minor corrections and one typo corrected. Added one referenc

Numerical simulation for Non-Fickian diffusion into fractured porous rock

A computer program has been developed which enables us to calculate the non-Fickian diffusion equations based on the Caputo fractional derivative. In recent years, the geological disposal method is, among to others, one of the most promising ways to dispose high-level radioactive wastes. It is therefore necessary to develop models for predicting solute transport in subsurface rock masses in order to assess and ensure the reliability for the geological disposal method. The conventional mathematical model of solute transport in rock masses is based on the Fick's law. However, because of existing complex fractures in the rock matrix, the conventional model tends to predict smaller solute travel distance than that in the actual transport process. The deficiency in the conventional model calls for the necessity of a more quantitative model which is applicable to the fractured porous media. In contrast, the non-Fickian diffusion model can provide realistic representation of actual fluid flow in the heterogeneous media. In the non-Fickian diffusion, the diffusion equation is described by fractional-in-space derivative of order α, which may vary from 0 to 1. In this study, we take advantage of the Caputo fractional derivative equation in order to develop a numerical method for analyzing the non-Fickian diffusion. We provide a numerical solution of the fractional derivative equation using implicit-finite difference method. The numerical result obtained for one dimensional diffusion equation using the computer program was shown to be in a good agreement with the analytical solution. The numerical method developed in this study was also verified with the result of laboratory experiment, in which a thermoluminescence technique was employed to trace the solute transport front in a granite sample. It has been shown that the numerical method based on the non-Fickian diffusion equation provides a better characterization of the experimental result, compared with the conventional diffusion equation. © 2006 American Institute of Physics

Therapeutics potentiating microglial p21-Nrf2 axis can rescue neurodegeneration caused by neuroinflammation

神経炎症の抑制を可能にする新規化合物を発⾒ --iPS-ドパミン神経前駆細胞の移植を促進--. 京都大学プレスリリース. 2020-11-16.Neurodegenerative disorders are caused by progressive neuronal loss, and there is no complete treatment available yet. Neuroinflammation is a common feature across neurodegenerative disorders and implicated in the progression of neurodegeneration. Dysregulated activation of microglia causes neuroinflammation and has been highlighted as a treatment target in therapeutic strategies. Here, we identified novel therapeutic candidate ALGERNON2 (altered generation of neurons 2) and demonstrate that ALGERNON2 suppressed the production of proinflammatory cytokines and rescued neurodegeneration in a 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)–induced Parkinson’s disease model. ALGERNON2 stabilized cyclinD1/p21 complex, leading to up-regulation of nuclear factor erythroid 2–related factor 2 (Nrf2), which contributes to antioxidative and anti-inflammatory responses. Notably, ALGERNON2 enhanced neuronal survival in other neuroinflammatory conditions such as the transplantation of induced pluripotent stem cell–derived dopaminergic neurons into murine brains. In conclusion, we present that the microglial potentiation of the p21-Nrf2 pathway can contribute to neuronal survival and provide novel therapeutic potential for neuroinflammation-triggered neurodegeneration

Numerical model of fluid flow through heterogeneous rock for high level radioactive waste disposal

An international consensus has emerged that deep geological disposal on land is one of the most appropriate means for high level radioactive wastes (HLW). The fluid transport is slow and radioactive elements are dangerous, so it's impossible to experiment over thousands of years. Instead, numerical model in such natural barrier as fractured underground needs to be considered. Field observations reveal that the equation with fractional derivative is more appropriate for describing physical phenomena than the equation which is based on the Fick's law. Thus, non-Fickian diffusion into inhomogeneous underground appears to be important in the assessment of HLW disposal. A solute transport equation with fractional derivative has been suggested and discussed in literature. However, no attempts were made to apply this equation for modeling of HLW disposal with account for the radioactive decay. In this study, we suggest the use of a novel fractional advection-diffusion equation which accounts for the effect of radioactive disintegration and for interactions between major, macro pores and fractal micro pores. This model is fundamentally different from previous proposed model of HLW, particularly in utilizing fractional derivative. Breakthrough curves numerically obtained by the present model are presented for a variety of rock types with respect to some important nuclides. Results of the calculation showed that for longer distance our model tends to be more conservative than the conventional Fickian model, therefore our model can be said to be safer. © 2007 American Institute of Physics

Space-time evolution induced by spinor fields with canonical and non-canonical kinetic terms

We study spinor field theories as an origin to induce space-time evolution. Self-interacting spinor fields with canonical and non-canonical kinetic terms are considered in a Friedman-Robertson-Walker universe. The deceleration parameter is calculated by solving the equation of motion and the Friedman equation, simultaneously. It is shown that the spinor fields can accelerate and decelerate the universe expansion. To construct realistic models we discuss the contributions from the dynamical symmetry breaking.Comment: 16 pages, 19 figure