1. Rehabilitation Clinical Trials Center, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California
2. Department of Respiratory and Critical Care Medicine, Beijing Chest Hospital, Capital Medical University, Beijing, China
3. Antioch Medical Center, Pulmonary Medicine, Antioch, California
4. High Specialization Rehabilitation Hospital, ORAS, Motta di Livenza, Italy