A handful of doctors providing medical services to students at UC San Diego — and their colleagues at nine other University of California campuses — went on strike Tuesday. It's the first time in 25 years that fully licensed doctors are picketing a U.S. employer, according to the Union of American Physicians and Dentists, which represents the physicians at the UC schools. The work stoppage began at 7:30 a.m. and is scheduled to last one day. It involves 150 health center doctors who manage the primary care and mental health needs of students.