1. Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8530, Japan, Siliconbio Inc., Higashi-Hiroshima, Hiroshima 739-0046, Japan, and Department of Economics, Toyo University, Bunkyo-Ku, Tokyo 112-8606, Japan