Martin Karplus speaks to the press after winning the 2013 Nobel Prize for chemistry in Cambridge, Massachusetts, October 9, 2013. Karplus, Michael Levitt and Arieh Warshel won the 2013 Nobel Prize for chemistry for the development of multiscale models for complex chemical systems, the award-giving body said on Wednesday. REUTERS/Dominick Reuter (UNITED STATES - Tags: SCIENCE TECHNOLOGY HEADSHOT)