Affiliation: | Columbia University, New York, NY 20027, USA;The State University of New York at Stony Brook, Stony Brook, LI, NY 11794, USA;Cornell University, Ithaca, NY 14853, USA;Louisiana State University, Baton Rouge, LA 70803, USA;Max Planck Institut für Physik, D-8000 Munich 40, Fed. Rep. Germany |