Professor, Computer Science and Engineering, University of California San Diego, July 2000 - present

Strategic Advisor to National Computational Science Alliance, March 2000 - present

Fellow, San Diego Supercomputer Center, September 2000 - present

Director, National Center for Supercomputing Applications, February 1985 - March 2000, University of Illinois at Urbana-Champaign

Professor, Astronomy and Physics Departments, August 1985 - March 2000, University of Illinois at Urbana-Champaign

Associate Professor, Astronomy and Physics Departments, August 1981 - August 1985, University of Illinois at Urbana-Champaign

Assistant Professor, Astronomy Department, August 1979 - August 1981, and Physics Department, August 1980 - August 1981, University of Illinois at Urbana-Champaign

Junior Fellow, Harvard Society of Fellows; in Departments of Physics and Astronomy, Harvard University, August 1976 - July 1979

Research Affiliate, Department of Physics, Yale University, September 1978 - July 1979

Research Associate, Princeton University Observatory, July 1975 - July 1976

Lecturer, Department of Astrophysical Science, Princeton University, September 1974 - June 1975

Research Assistant, University of Texas at Austin, Physics Depart-ment, 1972 - 1974; Stanford University, Physics Department, 1970 - 1971

NSF Pre-doctoral Fellow, University of Texas at Austin, 1972 - 1973; Stanford University 1970 - 1971