William G. Kaelin Jr.
William G. Kaelin Jr. stands with his son, Tripp, at a news conference, Monday, Oct. 7, 2019, in Boston, after he was awarded the Nobel Prize for Physiology or Medicine. Kaelin, who teaches at Harvard Medical School, shares the prize with Peter J. Ratcliffe and Gregg L. Semenza for their discoveries of how cells sense and adapt to oxygen availability, the Nobel Committee announced Monday. (AP Photo/Elise Amendola)