About the Authors

Xiaofeng Zhu

To whom correspondence should be addressed. E-mail: xzhu1@darwin.case.edu

Affiliation Department of Epidemiology and Biostatistics, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America

Richard S. Cooper

Affiliation Department of Preventive Medicine and Epidemiology, Stritch School of Medicine, Loyola University, Maywood, Illinois, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: RC XZ. Analyzed the data: XZ. Wrote the paper: RC XZ.