1. The Neuroenteric Clinical Research Group; Section of Gastroenterology; Southern Arizona VA Health Care System; University of Arizona Health Sciences Center; Tucson AZ USA
2. Esophageal and Swallowing Center; Division of Gastroenterology and Hepatology; MetroHealth Medical Center; Case Western Reserve University; Cleveland OH USA
3. Arizona Respiratory Center; College of Medicine; University of Arizona; Tucson AZ USA
4. The Division of Sleep Medicine; Brigham and Women's Hospital and Harvard Medical School; Boston MA USA
5. Biometric Department; Arizona Cancer Center; Tucson AZ USA