You learn what letter your blood type is (A, B, AB, and O). You also learn what your Rhesus, or RH, factor is. Your blood is either RH+, meaning the blood has the RH factor, or RH-, meaning the RH factor is not in your blood.he c, e, and d genes are negative RH genes; meaning there is no RH factor in the blood. Research shows only the âDâ gene causes sensitivity issues, so itâs the D gene that is of concern during your pregnancy. Thatâs why some care providers call the RH factor RH (D) positive or RH (D) negative.
Definition of RETARDATION. 1. : an act or instance of retarding. 2. : the extent to which something is retarded. 3. : a musical suspension; specifically: one that resolves upward. 4. a: an abnormal slowness of thought or action; especially: mental retardation b: slowness in development or progress.
A retarder is a device used to augment or replace some of the functions of primary friction-based braking systems, usually on heavy vehicles. Retarders serve to slow vehicles, or maintain a steady speed on declines, and help prevent the vehicle from running away by accelerating down the decline.They are not usually capable of bringing vehicles to a standstill, as their effectiveness diminishes as vehicle speed lowers.hey are usually used as an additional assistance to slow vehicles, with the final braking done by a conventional friction braking system. As the friction brake will be used less, particularly at higher speeds, their service life is increased.