<qa>  What is the name of the hospital that will be participating in the study?There will be about 500 subjects taking part in this study. They will come from participating Partners Hospitals, including Brigham and Womens Hospital, Massachusetts General Hospital, Faulkner Hospital, Newton-Wellesley Hospital, Spaulding Rehabilitation Hospital, and North Shore Medical Center. The U.S. Food and Drug Administration FDA has approved warfarin for use as a blood thinner. 