s they have almost every Friday for two years, Muslim students gathered at Duke University’s chapel for weekly prayers at midday Friday.. But a university plan to sound the prayer call from the Duke University Chapel’s 210-foot bell tower for the first time was hastily called off Thursday in the face of anti-Islamic tirades on social media and what a school official described as credible concerns about security. Instead, the call to prayer, or adhan, was sounded in Arabic and English on Friday from a small portable speaker set up on the chapel steps. Many among the hundreds of students...