Institute for Theoretical Physics, University of Münster, 48149 Münster, Germany; tdfrank(at)uni-muenster.de
Received 30 May 2002, accepted 23 September 2002 by U. Eckern
Universität zu Köln, Germany / Universidad de Concepción, Chile; grubilar(at)udec.cl
Received 21 June 2002, revised 23 September 2002,
accepted 23 September 2002 by F. W. Hehl
(1) ETH Zürich, Department of Materials, Institute of Polymers, ETH Zentrum, 8092 Zürich, Switzerland, ikarline(at)dove.ethz.ch; (2) Institute of Computational Modeling, Krasnoyarsk 660036, Russia
Received 4 June 2002, accepted 24 September 2002 by G. Röpke