DTM welcomed Carnegie Fellow Julie O'Leary this month. Julie defended her Ph.D. at the California Institute of Technology in September 2006. The focus of her thesis research was hydrogen isotope chemistry. She developed techniques to measure the hydrogen isotope composition of water-poor minerals and used those methods to constrain the hydrogen isotope composition of the mantle and of subduction zone systems. At DTM, her research will address a remaining question in the H-isotope chemistry of the mantle, the degree of D/H fractionation that occurs in melting systems.