Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, 104 S. Goodwin Avenue, Urbana, IL 61801, USA, E-mail: tsf@polymtl.ca
Associate Editor:
P. Desjardins
Dépt de Génie Physique, Ecole Polytechnique de Montreal, C.P. 6079; Succ. Centre Ville, Montréal, H3C 3A7, Canada. E-mail: tsf@polymtl.ca