A group of more than 600 doctors at the University of Maryland Medical Center voted to form a union, according to a preliminary vote tally. The tallied vote came in Thursday night as 628 voting for and 19 against. To win union certification, they needed just a simple majority of those who chose to vote. Ari Goldstein, a third-year family medicine resident, called it an “emotional day” for the doctors at medical centers, adding that organizers put “countless hours” into the union effort.