Universitry of Missouri-Columbia, USA; MashhoonB(at)missouri.edu
Received 1 March 2003,
accepted 11 March 2003 by F. W. Hehl
Institut für theoretische Physik, Technikerstr. 25, Universität Innsbruck, 6020 Innsbruck, Austria; christian.jaekel(at)math.polytechnique.fr
Received 6 January 2003,
accepted 31 March 2003 by K. Fredenhagen
Los Angeles; evertpost(at)aol.com
Received 12 February 2003, revised 9 April 2003,
accepted 11 April 2003 by F. W. Hehl
(1) Institute of Physics, Silesian University, 4 Uniwersytecka, 40-007 Katowice, Poland; (2) Institute of Physics, Humboldt University, Invalidenstr. 110, 10115 Berlin, Germany; matlak(at)us.edu.pl
Received 16 November 2002, revised 21 March 2003,
accepted 14 April 2003 by U. Eckern
Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany; hanke(at)physik.uni-wuerzburg.de
Received 5 March 2003, accepted 14 April 2003 by U. Eckern