We note with sadness the passing of two pioneers in computational science, John Dawson and Peter Kollman.

John Dawson

John M. Dawson, Professor of Physics at UCLA and Director of Special Projects of the Institute for Fusion and Plasma Research, died at his home in Los Angeles on November 17, 2001. He was 71. An international leader in plasma physics, Dawson is considered the father of computer-simulated plasma models and of plasma-based particle accelerators. He created the particle-in-cell modeling technique, which became one of the standard tools of computational plasma research.

Dawson received the James Clerk Maxwell Prize in Plasma Physics in 1977 and the American Physical Society's Aneesur Rahman Prize for Computational Physics in 1994. He holds numerous patents and has published over 300 papers in basic plasma physics, space plasma physics, applications of plasmas to high energy physics, and controlled fusion.

Peter Kollman

Peter Kollman died on May 25, 2001 at his home in San Francisco less than a month after being diagnosed with cancer. He was 56. Kollman, Professor of Pharmaceutical Chemistry at the University of California, San Francisco, was an international leader in computational studies of protein folding and molecular interactions. AMBER, the suite of molecular dynamics codes developed under his direction, is one of the most important tools of computational biology.

Kollman received the 1995 American Chemical Society Award for Computers in Chemical and Pharmaceutical Research, and the 1993 Computerworld Smithsonian Award. He was the author of more than 400 scientific journal articles and more than 50 book articles and chapters. His work was the 11th most cited among all chemists in the world during the period 1981-1997.