1. Institute for Advanced Study, Princeton, NJ 08540, USA
2. Thinking Machines Corporation, 245, First Street, Cambridge, MA 02142, USA
3. Physical Research Laboratory, Navrangpura, Ahmedabad 380009, India
4. School of Physica! Sciences, Jawaharlal Nehru University, New Delhi 110067, India
5. Department of Physica and Astronomy, University of Rochester, Rochester, NY 14627, USA