1. Institute for Health Policy Studies, University of California, 3333 California, Suite 265, San Francisco, CA 94143-0936, USA
2. Department of Physiological Nursing and Department of Epidemiology, School of Nursing and Medicine, University of California, San Francisco, CA 94143-0936, USA
3. Department of Community Health Systems, School of Nursing, University of California, San Francisco, USA
4. Department of Physiological Nursing, School of Nursing, University of California, San Francisco, USA