Irradiation

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irradiation

[i‚rād·ē′ā·shən]
(biophysics)
Subjection of a biological system to sound waves of sufficient intensity to modify their structure or function.
(engineering)
The exposure of a material, object, or patient to x-rays, gamma rays, ultraviolet rays, or other ionizing radiation.
(optics)
An optical illusion which makes bright objects appear larger than they really are.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Irradiation

 

in physiology, the spread of excitation or inhibition in the central nervous system. Irradiation plays an important part in cerebrocortical activity. The irradiation of excitation is manifested most distinctly after strong stimulation, when nerve centers usually not involved in a reflex response are drawn into the process. For example, moderate pain inflicted on the skin of an animal’s foot causes the paw to flex in the talocalcaneal joint. Increasing the force of stimulation causes the leg to flex in the knee and hip joints. In studying the effect of an inhibitory conditioned stimulus, I. P. Pavlov showed that inhibition can also spread (irradiate) in the cells of the cerebral cortex.


Irradiation

 

the apparent enlargement of the dimensions of white (light) objects against a black (dark) background (given the comparatively great brightness of the white object) or, conversely, the apparent diminution of the dimensions of black objects against a white background. (The first instance is called positive irradiation; the second, negative.)

As a result of irradiation, a thin black thread or wire observed against a bright flame seems to be interrupted in that segment, and the bright crescent of the new moon seems to have a larger diameter than the ash-gray disk of the moon seen simultaneously with it. The degree of irradiation increases when the brightness of the light background or object increases. Irradiation is caused by optical defects of the eye (spherical and chromatic aberrations), diffraction phenomena in the eye, and imperfect fixation of the eye on the objects observed.

REFERENCE

Kravkov, S. V. Glaz i ego rabota: Psikhofiziologiia zreniia, gigiena osvesh-cheniia, 4th ed. Moscow-Leningrad, 1950. (Includes bibliography.)
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The country has largely eliminated Salmonella contamination not by irradiating its poultry, but by using contaminant-free chicken feed, rat-proofed and disinfected pens, and other safeguards.
In 1982, FDA officials said that irradiating food with 1 kilogray of radiation was probably safe, but nothing has been done to study the effect of 7 kilograys, an amount it allowed for beef and lamb in 1997.
Estimated net social benefits (benefits minus costs) depend on the cost of irradiating ground beef and the extent of the foodborne illness prevented.
That petition is expected to come later this year when the USDA's Thayer publishes his results on irradiating sprouts to kill deadly E.
Although extensive research has been carried out on the microbiological and organoleptic effects of irradiating individual uncooked items, little work has been reported on the irradiation of mixed food systems, such as ready meals.
While exploring the chemistry of this fluorescent reaction, the researchers noticed that irradiating the antibody alone also produced hydrogen peroxide.
FDA found that while irradiating eggs would lower the food safety risks and cause no harmful side effects, the eggs also would contain less vitamin A.
While the color and odor of raw meat may be slightly affected, Olson said, cooking appears to lessen or eliminate the radiation-induced odor, and color changes can be minimized by irradiating meat in an oxygen-free environment in the frozen state.
He says he expects to begin irradiating poultry at his plant, in Mulberry, Fla., this month.
They found that irradiating the cooked pork sausage in aerobic packaging may result in a loss of some meaty aroma.
The laser's light was used to create X rays for irradiating a tiny spherical capsule containing gaseous hydrogen fuel.