This is an announcement for the paper "The group of isometries of a Banach space and duality" by Miguel Martin. Abstract: We construct an example of a real Banach space whose group of surjective isometries has no uniformly continuous one-parameter semigroups, but the group of surjective isometries of its dual contains infinitely many of them. Other examples concerning numerical index, hermitian operators and dissipative operators are also shown. Archive classification: math.FA Mathematics Subject Classification: Primary: 46B04. Secondary: 46B10, 46E15, 47A12 Remarks: To appear in J. Funct. Anal. The paper may be downloaded from the archive by web browser from URL http://front.math.ucdavis.edu/0809.3644 or http://arXiv.org/abs/0809.3644 or by email in unzipped form by transmitting an empty message with subject line uget 0809.3644 or in gzipped form by using subject line get 0809.3644 to: math@arXiv.org.