1. Institute for Protein Research, Osaka University, 3-2 Yamadaoka; Suita Osaka 565-0871 Japan
2. School of Social Sciences; Waseda University, 1-6-1 Nishi-Waseda; Shinjuku-ku Tokyo 169-8050 Japan
3. School of Science; Kitasato University, 1-15-1, Kitasato, Minami-ku; Sagamihara Kanagawa 252-0373 Japan
4. Graduate School of Information Sciences; Tohoku University, 6-3-09 Aoba, Aramaki-aza Aoba-ku; Sendai 980-8579 Japan