1. Pulmonary, Critical Care and Sleep Medicine, Olive-View Medical Center, Sylmar, CA, USA
2. David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
3. Pulmonary and Critical Care, Kaiser-Fontana Medical Center, Fontana, CA, USA
4. Pulmonary, Critical Care and Sleep Section, West Los Angeles VA Healthcare Center, Los Angeles, CA, USA