Confusion and a lot of questions exist as to detonation and pre-ignition. Sometimes you hear mistaken terms like pre-detonation. Detonation is one phenomenon that is abnormal combustion. Pre-ignition is another phenomenon that is abnormal combustion.
Martha R. Herbert, PhD, MD, is an assistant professor of neurology at Harvard Medical School, a pediatric neuroscientist at the Massachusetts General Hospital in Boston, and an affiliate of the Harvard-MIT-MGH Martinos Center for Biomedical Imaging.
And Iâm Sarah Long with People in America in VOA Special English. Today, we tell about a woman who worked to make a difference in peopleâs lives, Barbara Jordan. (THEME) VOICE ONE: Barbara Jordan was a lawyer, educator and member of Congress. She was well-known for her powerful, thoughtful speeches. During her long political career, Barbara Jordan worked for social change.