Received: 25 October 2017
Accepted: 20 April 2018
First Online: 3 May 2018
Ethics approval and consent to participate
: Ethics approval was obtained by the University of North Carolina at Chapel Hill Institutional Review Board (IRB) (study number 16–1837). The Office of Human Research Ethics at the University of North Carolina at Chapel Hill determined the study was exempt from further review according to the regulation under 45 CFR 46.101(b). Consent was deemed unnecessary because the study was observational and participants could not be identified from data used in the analysis and publication.
: The authors declare they have no competing interests to disclose.
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