Gray (unit) Gray (unit) The gray (symbol: Gy) is a derived unit of ionizing radiation dose in the International System of Units (SI). It is defined as the absorption of one joule of radiation energy per kilogram of matter. It is used as a unit of the radiation quantity absorbed dose which measures the energy deposited in a unit mass at a certain position, and of the radiation quantity kerma, which is the amount of energy that is transferred from photons to electrons per unit mass at a certain position. The corresponding cgs unit to the gray is the rad (equivalent to
Dictionary of Scientific Biography become the standard against which to measure all multi-volume biographical works in history of science." Dictionary of Scientific Biography The Dictionary of Scientific Biography is a scholarly reference work that was published from 1970 through 1980. It is supplemented by the New Dictionary of Scientific Biography. Both these publications are comprised in an electronic version, called the Complete Dictionary of Scientific Biography. The "Dictionary of Scientific Biography" is a scholarly English-language reference work consisting of biographies of scientists from antiquity to modern times, but excluding scientists who were alive when the "Dictionary" was first published. It includes scientists who worked