1. Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina
2. Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina
3. Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina; and Division of Pulmonary Diseases, Department of Medicine, University of North Carolina, Chapel Hill, North Carolina; martonen.ted@epa.gov