1. Contribution from the Division of Informatics for Natural Sciences, Graduate School of Human Informatics, Nagoya University, Nagoya 464-8601, Japan, Department of Physics, Graduate School of Science, Kyoto University & CREST (Core Research for Evolutional Science and Technology) of Japan Sciences and Technology Corporation, Kyoto 606-8502, Japan, and Department of Materials Physics and Chemistry, Graduate School of Engineering, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan