1. Vitamin K Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111
2. Department of Epidemiology, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111
3. Division of Biostatistics, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111