1. Stanford Center for Biomedical Ethics, Stanford University Medical School, Palo Alto, CA 94304, USA.
2. Department of Anthropology, University of Texas, Austin, TX 78712, USA.
3. Department of Sociology, New York University, New York, NY 10012, USA.
4. Department of Sociology, University of California, Berkeley, CA 94720, USA.
5. University of Wisconsin Law School, Madison, WI 53706, USA.
6. Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA.