Complex sentence: The focus of his research involves health, human behavior, and development, with a specific application to the domains of HIV/AIDS and drug abuse, which has addressed some of most important social and public health issues of our time.
Split into simpler sentences: The focus of his research involves health, human behavior, and development, with a specific application to the domains of HIV/AIDS and drug abuse. Halkitis has been able to address some of most important social and public health issues of our time.