1. Department of Pulmonary and Critical Care Medicine Zhujiang Hospital, Southern Medical University Guangzhou Guangdong China
2. Department of Pulmonary and Critical Care Medicine Suining Central Hospital Suining Sichuan China
3. Department of Pulmonary and Critical Care Medicine Second Affiliated Hospital of Chongqing Medical University Chongqing China
4. Department of Gastroenterology Medicine Suining Central Hospital Suining Sichuan China
5. Division of General Internal Medicine Mayo Clinic Rochester Minnesota USA
6. Department of Mathematics University of California Davis USA