Author, Rachel Carson Biographer; and Patricia DeMarco, Ph.D. Rachel Carson Scholar. March 5, 2015. The National Conservation Training Center invites prominent conservationists, writers, historians, scientists, filmmakers, and educators to discuss their work to a broad and interested public. In this program NCTC Historian, Dr. Mark Madison, hosts an interview with Mark Dixon, Filmmaker, “The Power of One Voice”; Linda Lear, Ph.D. Author, Rachel Carson Biographer; and Patricia DeMarco, Ph.D. Rachel Carson Scholar.