1. Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan
2. International Tomography Center, Siberian Branch of the Russian Academy of Science, Novosibirsk, Russia
3. Physics Department, Novosibirsk State University, Novosibirsk, Russia
4. A. P. Ershov Institute of Informatics Systems, Siberian Branch of the Russian Academy of Science, Novosibirsk, Russia
5. Graduate School of Science and Engineering, Saitama University, Saitama City, Japan