gamma; Γ, γ +

(Greek: Γ, γ; the third letter of the Greek alphabet; corresponding to g, as in go and as a numeral, it indicates 3)

agammaglobulinemia, agammaglobulinaemia
A rare disease where the body is unable to produce immune antibodies due to the lack of gamma globulin, a non-specific immunoglobulin, in the blood.

The disease can be acquired or inherited as an X-linked recessive genetic disease.

cosmic gamma rays
Rays coming from pulsars, radio galaxies, and quasars, although it is believed that they cannot penetrate the earth's atmosphere.
A letter occurring in certain early forms of Greek and transliterated in English as "w".

From Latin, which came from Greek di-, "two" + gamma, "gamma" (because its shape resembles two gammas).

1. The third letter of the Greek alphabet; Γ, γ.
2. The third item in a series or system of classification.
3. A unit of magnetic intensity equal to one hundred thousandth (10-5) of an oersted (unit measure of magnetic field strength in the centimeter-gram-second system).
4. A unit of mass equal to one millionth (10-6) of a gram.
5. In chemistry, the third position from a designated carbon atom in an organic molecule at which an atom or a radical may be substituted.
6. A number expressing the degree to which a negative has been developed as compared with the range of light values in the subject photographed.
gamma correction
1. A correction to the contrast of images and displays, performed by either software or hardware, and designed to correct for the fact that the intensity displayed on a cathode-ray tube is not linearly related to the input voltage.
2. Adjustments applied during the display of a digital representation of color on a screen in order to compensate for the fact that the Cathode Ray Tubes used in computer monitors, and televisions, produce a light intensity which is not proportional to the input voltage.

The light intensity is actually proportional to the input voltage raised to the inverse power of some constant, called gamma.

gamma counter
A device for detecting gamma radiation, primarily through the detection of fast electrons produced by the gamma rays; it either yields information about integrated intensity within a time interval or detects each photon separately.
gamma cross section
The cross section for absorption or scattering of gamma rays by a nucleus or atom.
gamma decay, gamma emission
A quantum transition between two energy levels of a nucleus in which a gamma ray is emitted.
gamma efferent fiber
Any of the motor nerve fibers that transmit impulses from the central nervous system to the intrafusal fibers (the striated fibers within a muscle spindle or a stretch receptor) of the muscle spindle.

The gamma efferent fibers are responsible for deep tendon reflexes, spasticity (increased tone of a muscle), and rigidity, but not for the degree of contractile response. They function in regulating the sensitivity of the spindle and the total tension of the muscle.

gamma flux density
The number of gamma rays passing through a unit area in a unit of time.
gamma gage, gamma-absorption gage
A penetration-type thickness gage that measures the thickness or density of a sample by measuring its absorption of gamma rays.
gamma globulin
1. A globulin present in blood plasma which contains antibodies effective against certain pathogenic micro-organisms.
2. Any of the serum proteins with antibody activity.
gamma heating
Heating resulting from absorption of gamma-ray energy by a material.
gamma irradiation
Exposure of a material to gamma rays.
gamma knife stereotaxic radiosurgery
A method for destroying deep-seated brain tumors with a focused beam of gamma radiation.

By using three-dimensional stereoscopic techniques to aim the radiation from several angles, it is possible to concentrate the energy on the tumor while minimizing damage to surrounding tissues.

You can see all of the letters of the Greek Alphabet on this page.