Employment

• Brown University, Professor, 1990-present
  Director of the Lefschetz Center for Dynamical Systems, 1999-2002
• University of Maryland-College Park: Associate Professor 1987 - 1990
• University of Maryland-College Park: Assistant Professor 1985-1987
• University of Arizona: Assistant Professor 1981 - 1985
• University of Minnesota-Minneapolis: Visiting Assistant Professor 1980 - 1981
• University of British Columbia: Postdoctoral Fellow 1980 (Jan - Jul)