Cuban President Raúl Castro turns 81 on Sunday, another year on in his race against time to reform Cuba's economy and try to assure the survival of communism after he and his elderly colleagues are gone. Their task, he has said, is to correct mistakes made during their 53 years of leadership, which will require "days and years of work" that he intends to finish. "The generation that made the (Cuban) revolution has had the historic privilege, few times seen, of being able to direct the rectification of errors they themselves committed," he told a Communist Party conference in January....