Iranian scientist Samira Asgari was one of many people from around the world caught in President Donald Trump’s executive order banning people from seven Muslim-majority countries from entering the U.S. On Saturday morning, Asgari was scheduled to fly from Frankfurt to Boston, where she had a visa to work as a post-doctoral fellow at Brigham and Women’s Hospital, to study the relationship between genetics and tuberculosis. But before she could board her flight, she was stopped by an U.S....