(AP) - Government nuclear experts are walking the streets in at least four major U.S. cities, using high-tech equipment hidden in briefcases and golf bags to hunt for radiological "dirty" bombs and other weapons terrorists might use. The Energy Department's Nuclear Incident Response Teams were deployed to Las Vegas, Los Angeles, New York and Washington last month, when the nation's terror alert status was upgraded to orange, or high alert, according two government officials who spokes on condition of anonymity.