Affiliation: | 1. Columbia Univ., New York, NY 10027, USA;2. Cornell Univ., Ithaca, NY 14853, USA;3. Louisiana State Univ., Baton Rouge, Louisiana 70803, USA;4. Max-Planck-Institut für Physik und Astrophysik, 8000 Munich 40, Federal Republic of Germany;5. State Univ. of New York at Stony Brook, Stony Brook, NY 11794, USA |