1. Institute of Industrial Science, The
University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo 153-8505,
Japan
2. Department of Basic Science, The University of
Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902,
Japan
3. Tokyo Instruments, Inc.,
Nishikasai 6-18-14, Edogawa-ku, Tokyo 134-0088, Japan