Sayles, John (sh) and attenuation factor (medicine)

Sayles, John (sh)

born Sept. 28, 1950, Schenectady, N.Y., U.S.

U.S. Film director.

He graduated from Williams College and wrote short stories and novels, including Union Dues (1977), before becoming a screenwriter for Roger Corman. He made his directorial debut with the acclaimed Return of the Secaucus Seven (1980). He explored social and political issues in Other thoughtful films such as Lianna (1982), Matewan (1987), Eight Men Out (1988), City of Hope (1991), Lone Star (1996), and Sunshine State (2002), and he usually wrote his own screenplays. He also directed the children's movie The Secret of Roan Inish (1994). Sayles was one of America's most successful independent filmmakers.

attenuation factor (medicine)

attenuation factor
<radiobiology> A measure of the opacity of a layer of material for radiation transversing it, the ratio of the incident intensity to the transmitted intensity. It is equal to Io/I, where Io and I are the intensities of the incident and emergent radiation, respectively. In the usual sense of exponential absorption (I = Ioe- m x), the attenuation factor is e- m x, where x is the thickness of the material and m is the absorption coefficient.

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