title: Introduction. Merrill P. Spencer.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Moehring
authors.forename: David T
authors.initials: DT
authors.lastname: Dobson
mesh_terms: D000818:Animals; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D010827:Physiology / Q000266:history*; D018608:Ultrasonography, Doppler / Q000266:history*; D014481:United States