Two American scientists who solved the enigma of how people can smell 10,000 different odors and recall them later were awarded the 2004 Nobel Prize in Physiology or Medicine yesterday. The winners, who will share the $1.3 million award, were Dr. Richard Axel, 58, a professor at Columbia University, and Dr. Linda B. Buck, 57, of the Fred Hutchinson Cancer Research Center and a professor at the University of Washington in Seattle. Until publication of their fundamental paper in 1991, the sense of smell had been "the most enigmatic of our senses," the Nobel Assembly of the Karolinska Institute in...