Two-dimensional crystal melting and D4-D2-D0 on toric Calabi-Yau singularities

We construct a two-dimensional crystal melting model which reproduces the BPS index of D2-D0 states bound to a non-compact D4-brane on an arbitrary toric Calabi-Yau singularity. The crystalline structure depends on the toric divisor wrapped by the D4-brane. The molten crystals are in one-to-one correspondence with the torus fixed points of the moduli space of the quiver gauge theory on D-branes. The F- and D-term constraints of the gauge theory are regarded as a generalization of the ADHM constraints on instantons. We also show in several examples that our model is consistent with the wall-crossing formula for the BPS index.Comment: 72 pages, 44 figure

Convergence and Refinement of the Wang-Landau Algorithm

Recently, Wang and Landau proposed a new random walk algorithm that can be very efficiently applied to many problems. Subsequently, there has been numerous studies on the algorithm itself and many proposals for improvements were put forward. However, fundamental questions such as what determines the rate of convergence has not been answered. To understand the mechanism behind the Wang-Landau method, we did an error analysis and found that a steady state is reached where the fluctuations in the accumulated energy histogram saturate at values proportional to $[\log(f)]^{-1/2}$. This value is closely related to the error corrections to the Wang-Landau method. We also study the rate of convergence using different "tuning" parameters in the algorithm.Comment: 6 pages, submitted to Comp. Phys. Com

Evaluation of water flushing effect on icebreaking operation of “Shirase” by analysis of Japanese Antarctic Research Expedition voyage data

The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Thu. 5 Dec. / 2F Auditorium , National Institute of Polar Researc

Can Japanese Firms Get Along with Highly Skilled Foreign Workers? : Intentions among Former International Students to Settle and Work in Japan

On the grounds that there are deficits in the work force, the Japanese government has proposed policies to facilitate the hiring of highly skilled foreign workers and to encourage Japanese firms to create conducive work environments for such workers. However, it remains unclear whether highly skilled foreign workers at Japanese firms intend to settle and work in Japan and whether firms’ implementation of human resources management (HRM) has been effective. This paper addresses these questions based on data obtained in a survey of former international students; international students have recently drawn attention as a source of highly skilled workers. We conducted an empirical analysis and offer the following suggestions. First, regarding settling and working in Japan, HRM policies that address former international students’ career development and position as foreigners must be implemented; doing so can reduce feelings of deprivation among them and mitigate their intention to leave Japan. Second, it was empirically determined that former international students have the intention of becoming target earners. Thus, in place of a policy that merely considers facilitating the entry of former international students into the Japanese labor market, it is better to provide systems that can encourage the circulation of migration. Third, it was shown that for former international students, the experience of studying in Japan may hamper their global transition; thus, it is necessary that Japanese educational institutions provide an environment where skills performable globally can be cultivated