1. Biomedical Science Corps: Public Health, Travis Air Force Base David Grant Medical Center, United States Air Force, Travis AFB, CA 94535, USA
2. Department of Epidemiology, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
3. Department of Health Policy and Management, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
4. Division of Biostatistics, Department of Preventive Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
5. Department of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA