Recent Trends in the Spread over Libor on the Domestic Straight Bond Trading Market in Japan

In this paper, we conduct a regression analysis on the spread over Libor (LS) on the domestic straight bond trading market in Japan from May 1997 through March 1998. Our analysis shows that, for non-construction issues, the lower the rating the higher the LS, and that the LS differential among issues with different ratings has expanded since around November 1997 against the background of a growing awareness of credit risk. Our analysis also shows that during the analysis period (May 1997 through March 1998) the coupon rate, which was previously a significant explanatory variable for the LS, lost its significance, and that the coefficient of the remaining maturity, which is also an explanatory variable, switched from negative to positive (the longer the period remaining until maturity, the higher the LS). The heightened awareness of credit risk among investors apparently contributed to both these phenomena, and the latter is particularly noteworthy because it is consistent with the results of empirical analyses in the United States. Finally, for construction issues, our analysis showed that the LS continued to increase following the bankruptcy of several construction companies during the summer of 1997, and that an extremely large premium has arisen for certain issues.

Risk Management for Equity Portfolios of Japanese Banks

This paper verifies the impact of equity portfolio on bank management, underscoring the importance of managing the risks involved and suggesting "management of sensitivity to equity price risk" as a risk management technique that takes into account the correlation between equity price risk and credit risk. To do this, the paper focuses on the high correlation between "expected default probability estimated by the option-approach (Merton method)" using equity price information and " spread over Libor" observed in the bond market. This is used to calculate sensitivity (delta and vega) to changes in the equity price and its volatility. According to calculations for a sample portfolio, these two sensitivities have a degree of utility in measuring the distribution of risk exposure and in using equity price index futures and options as hedges. In the hedging of vega risk (which tends to reflect credit risk) in particular, long put positions in equity price index options are shown to be potentially effective.

Energy- and temperature-dependent transport of integral proteins to the inner nuclear membrane via the nuclear pore

Resident integral proteins of the inner nuclear membrane (INM) are synthesized as membrane-integrated proteins on the peripheral endoplasmic reticulum (ER) and are transported to the INM throughout interphase using an unknown trafficking mechanism. To study this transport, we developed a live cell assay that measures the movement of transmembrane reporters from the ER to the INM by rapamycin-mediated trapping at the nuclear lamina. Reporter constructs with small (<30 kD) cytosolic and lumenal domains rapidly accumulated at the INM. However, increasing the size of either domain by 47 kD strongly inhibited movement. Reduced temperature and ATP depletion also inhibited movement, which is characteristic of membrane fusion mechanisms, but pharmacological inhibition of vesicular trafficking had no effect. Because reporter accumulation at the INM was inhibited by antibodies to the nuclear pore membrane protein gp210, our results support a model wherein transport of integral proteins to the INM involves lateral diffusion in the lipid bilayer around the nuclear pore membrane, coupled with active restructuring of the nuclear pore complex

Thermodynamic properties of the exactly solvable transverse Ising model on decorated planar lattices

The generalized mapping transformation technique is used to obtain the exact solution for the transverse Ising model on decorated planar lattices. Within this scheme, the basic thermodynamic quantities are calculated for different planar lattices with arbitrary spins of decorating atoms. The particular attention has been paid to the investigation of the transverse-field effects on magnetic properties of the system under investigation. The most interesting numerical results for the phase diagrams, compensation temperatures and several thermodynamic quantities are discussed in detail for the ferrimagnetic version of the model.Comment: 9 pages, 13 figures, submitted to Journal of Magnetism and Magnetic Material

A Proof of a Conjecture of Ohba

We prove a conjecture of Ohba which says that every graph $G$ on at most $2\chi(G)+1$ vertices satisfies $\chi_\ell(G)=\chi(G)$.Comment: 21 page

日本の研究者が海外で調査を行う際の注意点:倫理委員会から了承を得ること

In the globalised world more and more scholars conduct international research. Every research project must be morally justifiable, and in some countries, it is mandatory for all researchers, no matter which field they are in, to gain official ethical approval before conducting research that involves humans or animals. I explain the importance of following ethical guidelines when researchers conduct study in other countries, giving an example of the process for gaining ethical approval for educational research in the UK. I aim to help Japanese academics learn about ethical clearance when they conduct international research.グローバル化により、国際的な調査を行う研究者が増えてきた。研究プロジェクトには倫理的な正当性を持つことが義務付けられており、国によっては、人や動物を扱うすべての研究に、倫理審査の承認が義務づけられている。本稿では、国外で研究を行う際に倫理承認のガイドラインに従うことの重要性を説明したうえで、一例として英国での倫理承認のガイドラインとそのプロセスを紹介している。そして、日本在住の研究者が外国で研究調査を行う時の注意点なども述べている

Nonvolatile memory with molecule-engineered tunneling barriers

We report a novel field-sensitive tunneling barrier by embedding C60 in SiO2 for nonvolatile memory applications. C60 is a better choice than ultra-small nanocrystals due to its monodispersion. Moreover, C60 provides accessible energy levels to prompt resonant tunneling through SiO2 at high fields. However, this process is quenched at low fields due to HOMO-LUMO gap and large charging energy of C60. Furthermore, we demonstrate an improvement of more than an order of magnitude in retention to program/erase time ratio for a metal nanocrystal memory. This shows promise of engineering tunnel dielectrics by integrating molecules in the future hybrid molecular-silicon electronics.Comment: to appear in Applied Physics Letter