Duffield, N.G. 1989-91 Scholar Born U.K. Ph.D. 1987 London. Appointments: Research Assistant, UCD 1986-88; Royal Society Fellow, Heidelberg 1988-89; Research Fellow, DCU 1991-93; Assistant Lect., DCU 1993-95; AT&T Labs 1995-. Address: AT&T Bell Labs., 180 Park Av., Room B139, Florham Park, NJ 07932, USA. E-mail: duffield_at_research.att.com