Helene Gayle is an AIDS expert who has been working in many different initiatives in the US, among them the Centers for Disease Control (CDC). She also works in President Obama's advisory group on HIV/AIDS. Here she talks about understanding and changing behaviors.

Praphan Phanupak is Professor in Immunology and the Director of the Thai Red Cross AIDS Research Centre (TRC-ARC). He talks about the incidence and prevalence of HIV infection in different parts of Thailand and about human experiments on Thai drug users.