At least 87 subjects (enrollment target: 135 subjects) will be selected from qualifying normal volunteers. Age range will be from ≥18 to 90 years. The age of the subjects will be defined by their month of birth versus the month of giving consent to participate in this study. A subject who is 40 years and 11 months old will be counted as being in the age group "31 to 40 years". Each site will attempt to recruit subjects in about equal numbers in each age group. The distribution in the age groups should be fairly equal among subjects in each ethnic group alone.