Cuba has begun its transition to rule by someone whose last name isn't Castro and is young enough not to have fought alongside Fidel Castro in the revolution that ushered in communism in 1959. As Cuba tinkers with market-based economic reforms, the man to watch, the new number two guy in the regime, is Miguel Diaz-Canel, 52. He is an electrical engineer by profession who has long been active in the communist party at the provincial level and gradually worked his way up, under the wings of the current president, Raul Castro. In 2003 he was named to the Politburo of the party.