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opacity

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opacity

1. the state or quality of being opaque
2. an opaque object or substance
3. Physics Photog the ratio of the intensity of light incident on a medium, such as a photographic film, to that transmitted through the medium
4. Logic Philosophy the property of being an opaque context
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

opacity

(oh-pass -ă-tee) A measure of the ability of a gaseous, solid, or liquid body to absorb radiation. It is the ratio of the total radiant energy received by the body to the total energy transmitted through it. For gaseous material of a particular chemical composition, opacity depends on both temperature and density. Various processes contribute to the opacity: energy absorption by electrons bound to an atom or ion, allowing them to jump to a higher level or to escape from the atom as free electrons (bound-bound or bound-free absorption); absorption by free electrons (free-free absorption); scattering of photone of radiation by free electrons or atoms (Compton scattering); absorption of γ-ray photons by ambient ‘gas' photons (photon-photon absorption). The negative hydrogen ion, H, is a particularly important source of opacity in a star like the Sun, and the solar opacity is seen to drop rapidly to zero at the Sun's limb.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006

Opacity

Quality of being impenetrable by light; not reflecting light, or transmitting light, neither transparent nor translucent.
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved

opacity

[ō′pas·əd·ē]
(optics)
The light flux incident upon a medium divided by the light flux transmitted by it.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

opacity

The quality of being opaque, as the capacity of a paint to cover or obliterate a background over which it is applied.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

opacity

Being "opaque," which prevents light from shining through. For example, in an image editing program, the opacity level for some function might range from completely transparent (0) to completely opaque (100).
Copyright © 1981-2025 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
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References in periodicals archive
A fifth of adults 40 years and above in Nigeria are reported to have some degree of lens opacity. In 2005, data from the Ophthalmological Society of Nigeria indicated that about 1.2 million people in Nigeria were blind due to cataract and about 4.08 million people had low vision.
In total, 2288 individuals (4576 eyes) participated in this study, among which 129 subjects (258 eyes) were excluded from the study due to pseudophakia (172), keratopathy (23), atrophy of eyeball (7), or severe lens opacity (56).
Next to the normal mammographic study and dense breast is speculated opacity and circumscribed opacity constituting 10.41% and 5.45% respectively suggest high prevalence of malignant findings over suspicious and benign findings in positive mammographic changes and necessitate the importance of mammography in initial screening for breast diseases.
There is little empirical work that compares the effectiveness of these opacity proxies and their relation to one another.
Chest X-ray typically shows diffuse interstitial infiltrates.2,10 Findings on CT of the chest include ground-glass opacities, dense consolidation, pulmonary nodules and, less commonly, irregular linear opacities.3,4,11 In our case, the most pronounced CT finding was bilateral alveolar opacity.
The affected eye was cleaned with normal saline in the cases of descemetocele and corneal opacity (Ramani et al., 2010).
The authors propose an alternative method based on use of mathematical models of opacity of the exhaust gases in free acceleration mode in a function from a movement rate of fuel feed pedal [13, 14].
It can be concluded safely from the above mentioned discussions that Pakistan has adopted nuclear policy of opacity by keeping in view its military, geographical and strategic strengths and weaknesses.
Dry film opacity is a form of evaluating the vesiculation of the synthesized polyester particles.
In this paper, we discuss verification of opacity and diagnosability for pushdown systems based on basic results in formal language theory [5, 6].
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