The nuclear crisis has escalated in Japan. There have been partial meltdowns in three nuclear reactors, breaches in the protective containment walls of two of them, and a fire in another. U.S. warships have changed course because of the dangers of rising radiation, and the Japanese Army decided it was too dangerous to fly helicopters over the plants. But 50 workers remain at the heart of the plant, literally risking their lives to avert a catastrophe at Fukushima Daiichi Nuclear Power Station. Keith Bradsher is The New York Times Hong Kong bureau chief. He says that we don’t know much about these heroic workers.