- Correspondence to Dr Jennifer Tjia, Division of Epidemiology and Chronic Diseases, University of Massachusetts Medical School, Albert Sherman Building, 368 Plantation Street, AS8-2068, Worcester, MA 01605, USA;
- Received November 13, 2014
- Revision received January 1, 2015
- Accepted February 17, 2015
- First published March 26, 2015.
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