He has received many other honors, including the Franklin Medal of the Franklin Institute and the John J. Carty Medal of the National Academy of Sciences, as well as honorary degrees from Cambridge, Oxford, Yale, Columbia and the University of Chicago. He was for many years a Citizen Regent of the Smithsonian Institution and he has been a director of the J.D. and C.T. MacArthur Foundation since 1979. He is a member of the President's Council of Advisors on Science and Technology and belonged to a similar body advising President Nixon. Twice invited to speak at the World Economic Forum, Gell-Mann is a member of the National Academy of Sciences, the American Academy of Arts and Sciences, and the American Philosophical Society and a foreign member of the Royal Society ofLondon. He is the author of The Quark and the Jaguar and his recent research at the Santa Fe Institute has focused on “plectics,” the study of simplicity and complexity.