model for somatic effects in the Nuclear Regulatory Commission's reactor-safety study.

ERIC J. HALL is Higgins Professor of Radiation Biophysics and professor of radiology and radiation oncology at Columbia University. Dr. Hall's research has included study of the effects of ionizing radiation on cells in culture and mechanisms of carcinogenesis. He was a member of the BEIR V committee. He has received awards from several radiology societies, including the gold medal of the Radiological Society of North America, the gold medal of the American Society of Therapeutic Radiology and Oncology, the Failla Award of the Radiation Research Society, and the Silvanus Thompson Award of the British Institute of Radiology.

WARREN K. SINCLAIR is president emeritus of the National Council on Radiation Protection and Measurements and emeritus professor of radiobiology at the University of Chicago. Dr. Sinclair's research has focused on radiologic physics, radiation biology, and radiation protection and included cell-cycle studies in mammalian cells and radiation risk estimates in humans. He has served as president of the Radiation Research Society and the American Association of Physicists in Medicine and was secretary general of the Fifth International Congress of Radiation Research. He has been Curie Lecturer, Failla Lecturer, Parker Lecturer, and Taylor Lecturer and has received the Coolidge Award. He served on the International Commission on Radiological Protection, the U.S. delegation to UNSCEAR, and the International Commission on Radiation Units and Measurements.