1. School of Nursing, University of Rochester Medical Center, Rochester, NY, USA
2. Departments of Mathematics, Vanderbilt University, Nashville, TN, USA
3. Department of Mathematics, Shanghai University, Shanghai, People’s Republic of China
4. Departments of Biostatistics, Vanderbilt University, Nashville, TN, USA
5. School of Public Health, Yale University, New Haven, CT, USA
6. Department of Public Health Science, University of Rochester Medical Center, Rochester, NY, USA