In partial fulfillment of the requirements for the Degree of Doctor of Philosophy in the School of Biology Natasha De Leon will defend her thesis "Microbes in the atmosphere: prevalence, species composition, and implications for cloud formation" on Wednesday, March 25, 2015 at 2:00 PM in the ES&T Building, room L1120. Thesis Advisor: Dr. Kostas Konstantinidis, School of Civil and Environmental Engineering, Georgia Institute of Technology. Committee Members: Dr. Brian Hammer, School of Biology, Georgia Institute of Technology; Dr. Thomas DiChristina, School of Biology, Georgia Institute of Technology; Dr. King Jordan, School of Biology, Georgia Institute of Technology; Dr. Athanasios Nenes, School of Earth & Atmospheric Sciences, School of Chemical and Biomolecular Engineering, Georgia Institute of Technology.