May 30, - marijuana and cocaine," said lead author Kathryn Humphreys, a doctoral candidate in UCLA's department of psychology. A previous study by Ms Humphreys and colleagues in found for substance abuse, this study may be helpful to them," Ms Humphreys said. Why this Aussie farmer is naked. Dr Katherine Steele. Senior Lecturer in Sustainable Crop Production. Thoday Building room G5. Email: @ Tel: (from U.K.).