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 It might be outdated or ideologically biased.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 ?
WHO/IAEA/FAO has approved the irradiation processing as non-heat treatment technology which has high usefulness and safety for controlling microorganism deterioration of foods [4].
Determination of irradiation induced hydrocarbons is a chemical method applied for identification of irradiated fat-containing foods.
As cloudy sky conditions were modelled only for a few places in Slovenia, we were seeking for a more universal irradiation model.
New Solar Irradiation Model SISIM for Horizontal Surfaces
A recent temperature coefficient study of FWT alanine dosimeters focused on irradiation temperatures in excess of 50 [degrees]C measured a temperature coefficient of 0.12 %/K at 1 kGy and a temperature coefficient of 0.10 %/K at 20 kGy that was linear up to 70 [degrees]C (4).
The only previous publication to directly compare Harwell and FWT dosimeters did conclude their respective temperature coefficients were equivalent but was limited to a maximum dose of 50 kGy and maximum irradiation temperature of 50 [degrees]C (8).
(2010) reported that irradiation of 1 kGy for sliced cheese and 3 kGy for pizza cheese were sufficient to lower the total aerobic bacteria to undetectable level.
As described, a low dose irradiation can improve the microbial quality significantly and reduce the risk of contamination of cheese products by the food-borne pathogens which can potentially occur during processing, however, the quality changes of such irradiated cheese products has not been well documented.
Radiation sensitive indicator based on tetrabromo phenol dyed polyvinyl alcohol was developed to be use in food irradiation where the dose between 1-8 kGy [9].
The effect of gamma irradiation on the optical and electrical properties of manganese phthalcyanine polymer (MnPC) thick films were investigated for dosimetry applications [12], the effect of gamma irradiation on the optical properties of polystyrene doped by methylene blue have been investigated, the optical band Eg was determined and was found to decrease after irradiation [13].
The trend of CH in the aromatic skeletal region with the irradiation time, which is closely related to a change in color of wood, is not inconsistent with previous reports (Tolvaj and Faix 1995, Barta et al.
The ratio ([R.sub.[lambda]]) of [d.sup.2]A/d[[lambda].sup.2] after light-irradiation to before irradiation was investigated.