1. Device/System Group, WPI-Advanced Institute for Materials Research (AIMR), Tohoku University, 2-1-1, Katahira, Aoba-Ku, Sendai 980-8577, Japan
2. Mathematical Science Group, WPI-Advanced Institute for Materials Research (AIMR) and MathAM-OIL, Tohoku University and AIST, 2-1-1, Katahira, Aoba-Ku, Sendai 980-8577, Japan
3. Department of Mathematics, Asahikawa Medical University, 2-1-1-1, Midorigaoka-higashi, Asahikawa 078-8510, Japan