Affiliation: | 1. Research Center for Advanced Science and Technology , The University of Tokyo , 4-6-1 Komamba, Meguro-ku, Tokyo, 153, Japan;2. Physics Department , Rensselaer Polytechnic Institute , Troy, NY, 12180-3590, U.S.A.;3. Department of Physics and Astronomy , University of Wyoming , Laramie, WY, 82071, USA;4. Department of Physics and Astronomy , University of Wyoming , Laramie, WY, 82071, USA |