SAN FRANCISCO — Jacqueline Nguyen knows adversity. She, her siblings and their parents fled Vietnam, and the 10-year-old Nguyen spent her first days in the United States in 1975 in a refugee tent city at Camp Pendleton in California. Nguyen, 50, says her parents’ perseverance to provide for their six children and start a new life in a foreign country has inspired her to seize opportunities even when they may be difficult or new. Now a federal appeals court judge, Nguyen may need to summon that inspiration again if President Barack Obama names her as his pick for the U.S.