1. United States Air Force, Biomedical Sciences Corps: Public Health Division, Travis AFB, California, David Grant Medical Center 60th Aerospace Medicine Squadron Office of Public Health 101 Bodin Circle 94535, USA
2. Department of Epidemiology, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA
3. Department of Health Policy and Management, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA
4. Division of Biostatistics and Center for Population Sciences, Department of Preventive Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
5. Department of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA