NEW YORK Officials tried to tamp down New Yorkers' fears Friday after a doctor was diagnosed with Ebola in a city where millions of people squeeze into crowded subways, buses and elevators every day. "We want to state at the outset that New Yorkers have no reason to be alarmed" by the doctor's diagnosis Thursday, said Mayor Bill de Blasio, even as officials described Dr. Craig Spencer riding the subway, taking a cab and bowling since returning to New York from Guinea a week ago.