1. Department of Epidemiology Gillings School of Global Public Health University of North Carolina at Chapel Hill Chapel Hill North Carolina USA
2. Center for Esophageal Diseases and Swallowing Center for Gastrointestinal Diseases and Biology Division of Gastroenterology and Hepatology Department of Medicine School of Medicine University of North Carolina at Chapel Hill Chapel Hill North Carolina USA
3. Department of Surgery School of Medicine University of North Carolina at Chapel Hill Chapel Hill North Carolina USA