Prostate-specific antigen (PSA) is a substance produced by the prostate gland. Elevated PSA levels may indicate prostate cancer, a noncancerous condition such as prostatitis, or an enlarged prostate.
Dolby Digital, formerly known as AC-3, is a digital audio coding technique that reduces the amount of data needed to produce high quality sound. Dolby Digital takes advantage of how the human ear processes sound.
The Doppler Effect. In clinical routine, Doppler echocardiography is used used to measure velocities and direction of blood flow in the heart chambers and vessels according to the Doppler effect, which was described by Christian Doppler. He discovered that stars appear of different colours when observed from a constant position on earth.