1. Department of Internal Medicine, Section of Pulmonary, Critical Care, and Sleep Medicine, Yale School of Medicine, New Haven, CT
2. PET center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT
3. Department of Psychiatry, Yale School of Medicine, New Haven, CT
4. Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT
5. Department of Psychology (Health Program) and Center for the Study of Tobacco Products, Virginia Commonwealth University, Richmond, VA