GALE ENCYCLOPEDIA OF MEDICINE 2 1603 Hepatitis C 24. Carbon-14, or radiocarbon, has a half-life of 5,730 years, meaning that it is useful for analyz- ing only fairly recent samples. This theorem can be proved using (3. Shading could also improve transpiration efficiency by reducing heat stress that unshaded crops frequently experience in areas of high incident radiation and temperature (Ong et al.