Funding for this research was provided by:
National Institute on Drug Abuse (R01DA039071, K01DA040543)
National Institutes of Health (P30 AI036214)
Received: 30 October 2017
Accepted: 9 August 2018
First Online: 14 August 2018
Ethics approval and consent to participate
: This study (#150512) was approved by ethics committees at the University of California, San Diego, Xochicalco University in Tijuana, and SADEC-FEMAP in Ciudad Juarez. All participants provided written informed consent to participate.
: Not applicable.
: The authors declare that they have no competing interests.
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