1. Department of Materials and Life Science, Seikei University, Tokyo 180-8633, Japan
2. Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Matsue, Shimane 690-8504, Japan
3. National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, U.K.
4. Corporate Engineering Division, Appliances Company, Panasonic Corporation, Kyoto 619-0237, Japan