From the NY Times: Kiyoshi Ito, 93, Mathematician Who Described Random Motion, Dies - Obituary (Obit) - NYTimes.com:
"Kiyoshi Ito, a mathematician whose innovative models of random motion are used today in fields as diverse as finance and biology, died Nov. 17 at a hospital in Kyoto, Japan. He was 93....Mr. Ito is known for his contributions to probability theory, the study of randomness. His work, starting in the 1940s, built on the earlier breakthroughs of Albert Einstein and Norbert Wiener. Mr. Ito’s mathematical framework for describing the evolution of random phenomena came to be known as the Ito Calculus."