Roentgen (unit) this derivative quantity the roentgen equivalent physical (rep) to distinguish it from the ICR roentgen. The introduction of the roentgen measurement unit, which relied upon measuring the ionisation of air, replaced earlier less accurate practices that relied on timed exposure, film exposure, or fluorescence. This led the way to setting exposure limits,and the National Council on Radiation Protection and Measurements of the United States established the first formal dose limit in 1931 as 0.1 roentgen per day. The International X-ray and Radium Protection Committee, now known as the International Commission on Radiological Protection (ICRP) soon followed with a limit of
The Amazing Race en Discovery Channel 2 route markers in this season were coloured blue and black, including the clue envelopes and the Pit Stop. None of the eliminated teams were present at the Finish Line. Applications were accepted from 13 December 2009 and finished on 8 February 2010. Semi-finalist interviews were held sometime in March 2010 and the final casting interviews took place around April 2010. According to Discovery's official website, the four official sponsors of the second season of "The Amazing Race en Discovery Channel" were Bridgestone, Samsung, Visa and Wii Party. The sponsors played a major role in the series by providing prizes and