1. Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan, Faculty of Pharmaceutical Science, Nagoya City University, 3-1, Tanabedori, Mizuho-ku, Nagoya 467-8603, Japan, and Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan