Author(s): Iver Brevik, Kimball A. Milton, Shin'ichi Nojiri, and Sergei D.
Odintsov
-- hep-th/0010205 was replaced with a revised version
on Wed, 1 Nov 2000 16:07:49 GMT (12kb) --
Paper: hep-th/0010205
Comments: 15 pages, REVTeX, no figures. New version inclues extended discussion
and examples in Sec. IV
Report-no: OKHEP-00-11
URL: http://arXiv.org/abs/hep-th/0010205