1. Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska68588-0304, United States
2. Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, Nebraska68588-0304, United States
3. Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania15213-3301, United States
4. Department of Statistics, University of Nebraska-Lincoln, Lincoln, Nebraska68583-0963, United States
5. Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado Anschutz Medical Campus, Aurora, Colorado80045-2609, United States
6. Department of Applied Statistics and Operations Research, Bowling Green State University, Bowling Green, Ohio43403-0001, United States