Positions Held
- Member of the Governing Council of the National Academy of Sciences (2005-2008)
- Chair of the Division o f Fluid Dynamics of the American Physical Society (2005)
- John and Barbara Bush Professor of Physics at Haverford College
- Member of the National Academy of Sciences (1993- )
- Fellow of the American Academy of Arts and Sciences
- Adjunct Professor of Physics at University of Pennsylvania
- Member of the Graduate Group in Mechanical Engineering and Applied Mechanics (1985-1999)
- Co-Chair, NRC Committee on Programs for Advanced Science and Math Secondary Education (2000-02)
- Council and Executive Board of the American Physical Society (various times over a 10 year period)
- Member of the NRC Commission on Physical Sciences, Mathematics, and Applications (1998-2000)
- Advisory Board of the National Science Resources Center, National Academy of Sciences (1995-2000)
- Member of the American Physical Society Executive Board and Council (2001-2002)
- Boards of Editors: Physics of Fluids (current); Physical Review Letters (2003-2005); Journal of Nonlinear Science (1990-93); Physical Review A (1986-89), and American Journal of Physics (1985-88)
- Belkin Professor, The Weizmann Institute of Science during 1997-98. Visiting Professor at Paris VII and Ecole Normale (1991 and 1985)
- Provost of Haverford College (1988-90)
- Project Director of the Mid-Atlantic Pew Science Program in Undergraduate Education (1987-90).
- Secretary-Treasurer, Division of Fluid Dynamics of the APS (1985-88)