Funding for this research was provided by:
National Institute on Drug Abuse (R01DA037117)
Received: 31 May 2019
Accepted: 4 December 2019
First Online: 19 December 2019
Ethics approval and consent to participate
: The study was approved by the IRBs of the University of Nebraska-Lincoln and the University of Puerto Rico. Written informed consent was obtained from all subjects.
: Not applicable.
: The authors declare that they have no competing interests.