Affiliation: | (1) Department of Materials Soience and Metallurgy, University of Cambridge, Pembroke Street, CB2 3QZ Cambridge, U.K.;(2) Churchill College, CB3 ODS Cambridge, U.K.;(3) Present address: Dominion Radio Astrophysical Observatory, PO Box 248, V2A 6K3 Penticton, B. C., Canada;(4) Present address: Department of Metallurgy and Materials Science, University of Nottingham, NG7 2RD Nottingham, U.K. |