Black Hole Formation and Explosion from Rapidly Rotating Very Massive Stars

We explore the formation process of a black hole (BH) through the pair-instability collapse of a rotating Population III very massive star in axisymmetric numerical relativity. As the initial condition, we employ a progenitor star which is obtained by evolving a rapidly rotating zero-age main sequence (ZAMS) star with mass $320M_\odot$ until it reaches a pair instability region. We find that for such rapidly rotating model, a fraction of the mass, $\sim 10M_\odot$, forms a torus surrounding the remnant BH of mass $\sim 130M_\odot$ and an outflow is driven by a hydrodynamical effect. We also perform simulations, artificially reducing the initial angular velocity of the progenitor star, and find that only a small or no torus is formed and no outflow is driven. We discuss the possible evolution scenario of the remnant torus for the rapidly rotating model by considering the viscous and recombination effects and show that if the energy of $\sim 10^{52}$ erg is injected from the torus to the envelope, the luminosity and timescale of the explosion could be of the orders of $10^{43}$ erg/s and yrs, respectively. We also point out the possibility for observing gravitational waves associated with the BH formation for the rapidly rotating model by ground-based gravitational-wave detectors.Comment: 19 pages, 16 figures, submitted to Ap

Reforming Knowledge? A Socio-Legal Critique of the Legal Education Reforms in Japan

This article critiques the current Japanese legal education reforms, modeled largely on the United States, by proposing a socio-technical framework for analyzing the distribution of legal expertise in a given society. On one side of the spectrum is the monocentric model of legal expertise, in which expertise is monopolized by the profession and legal literacy is low. On the other side of the spectrum is the polycentric model of legal expertise, in which a range of social and institutional actors share responsibility for legal expertise and legal literacy is high. If the U.S. is a more monocentric system, the Japanese system has historically been more polycentric. The article evaluates the strengths and weaknesses of the two kinds of systems, focusing on the role of legal knowledge workers who are not professional lawyers in Japan. It concludes that although each system has strengths and weaknesses, a polycentric model of legal knowledge distribution is ultimately more economically efficient and better suited to the goals of a liberal democratic society than a monocentric model. For this reason, the rush to emulate the American system in current Japanese reforms is seriously flawed

Reforming Knowledge? A Socio-Legal Critique of the Legal Education Reforms in Japan

This article critiques the current Japanese legal education reforms, modeled largely on the United States, by proposing a socio-technical framework for analyzing the distribution of legal expertise in a given society. On one side of the spectrum is the monocentric model of legal expertise, in which expertise is monopolized by the profession and legal literacy is low. On the other side of the spectrum is the polycentric model of legal expertise, in which a range of social and institutional actors share responsibility for legal expertise and legal literacy is high. If the U.S. is a more monocentric system, the Japanese system has historically been more polycentric. The article evaluates the strengths and weaknesses of the two kinds of systems, focusing on the role of legal knowledge workers who are not professional lawyers in Japan. It concludes that although each system has strengths and weaknesses, a polycentric model of legal knowledge distribution is ultimately more economically efficient and better suited to the goals of a liberal democratic society than a monocentric model. For this reason, the rush to emulate the American system in current Japanese reforms is seriously flawed

Quantitative Temperature Dependence of Longitudinal Spin Seebeck Effect at High Temperatures

This article reports temperature-dependent measurements of longitudinal spin Seebeck effects (LSSEs) in Pt/Y$_3$Fe$_5$O$_{12}$ (YIG)/Pt systems in a high temperature range from room temperature to above the Curie temperature of YIG. The experimental results show that the magnitude of the LSSE voltage in the Pt/YIG/Pt systems rapidly decreases with increasing the temperature and disappears above the Curie temperature. The critical exponent of the LSSE voltage in the Pt/YIG/Pt systems at the Curie temperature was estimated to be 3, which is much greater than that for the magnetization curve of YIG. This difference highlights the fact that the mechanism of the LSSE cannot be explained in terms of simple static magnetic properties in YIG.Comment: 9 pages, 5 figures, 1 tabl