Dr. Suzanne Barakat was writing a prescription for one of her patients at San Francisco General Hospital when her phone lit up with text messages from friends sending condolences. It was Feb. 10 and Barakat, 27, was in her first year of family medicine residency. She ignored the first text, thinking it was either a mistake or a reference to family members in war-torn Syria. “I just put my head back to work,” she said. But then Barakat noticed that one of the texts mentioned her 23-year-old brother, Deah Barakat, a dental student at the University of North Carolina in...