screening

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screening

[′skrēn·iŋ]
(atomic physics)
The reduction of the electric field about a nucleus by the space charge of the surrounding electrons.
(electromagnetism)
(engineering)
The separation of a mixture of grains of various sizes into two or more size-range portions by means of a porous or woven-mesh screening media.
The removal of solid particles from a liquid-solid mixture by means of a screen.
The material that has passed through a screen.
(industrial engineering)
The elimination of defective pieces from a lot by inspection for specified defects. Also known as detailing.

screening

the use of academic qualifications as a means of selecting among candidates for employment, where it is the general level of academic qualification which is decisive rather than the particular content of the education. In this process, an employer may use educational qualifications, or sometimes also the type of institution attended, as a proxy for ‘general intelligence’, ‘perseverance and motivation’, or other 'social background’, instead of being interested in the specific content of the education received. see also CULTURAL CAPITAL.

According to the screening hypothesis, it is the screening process rather than any direct economic return on education which explains part of the correlation between level of education and level of income. This hypothesis provides an account of the effects of education which is at odds with other hypotheses (compare HUMAN CAPITAL). See also CREDENTIALISM, CULTURAL CAPITAL.

Screening

 

the sorting on screens of bulk materials according to particle size. Screening is used to separate coal, ore. building materials, and other bulk materials into fractions or to sort out particles of a given size. For example, in the production of crushed gravel (about 200 million cu m in the USSR in 1970). a mass of raw sand and gravel is sorted out into five fractions (70–40 mm. 40–20 mm, 20–10 mm, 10–5 mm, and less than 5 mm). During screening, the material is separated into layers as it moves along the sieve of the screen: the larger the particles, the higher the layer along which they move. Particles that are smaller than the screen openings (so-called lower grade) fall through the openings upon reaching the screen’s surface (screen underflow); larger particles (so-called upper grade) slide along the sieve and form the screen overflow. Because of limitations on the length of the screen, not all particles that are smaller than the sieve openings fall through; some remain in the screen overflow, contaminating it and reducing the quantity of the underflow.

The efficiency of screening depends on many factors: the size and shape of the particles in the initial material and the load it exerts on the screen, the type of screen, and the size and shape of the openings in the sieve, its length, and its angle of inclination. The maximum efficiency of trommels is 60–70 percent: of shaking screens. 70–80 percent; and of vibrating screens, 90–98 percent. Screening on sieves with openings of 3 mm and more is widespread in industry; openings of 1 mm are rarely encountered. Hydraulic classification or air separation is usually used to sort materials containing particles smaller than 1–3 mm. Since screening ensures high-quality sorting, its use is spreading, particularly the use of sieves with small openings.

Screening

A mechanical method of separating a mixture of solid particles into fractions by size. The mixture to be separated, called the feed, is passed over a screen surface containing openings of definite size. Particles smaller than the openings fall through the screen and are collected as undersize. Particles larger than the openings slide off the screen and are caught as oversize. A single screen separates the feed into only two fractions. Two or more screens may be operated in series to give additional fractions. Screening occasionally is done wet, but most commonly it is done dry.

Industrial screens may be constructed of metal bars, perforated or slotted metal plates, woven wire cloth, or bolting cloth. The openings are usually square but may be circular or rectangular. See Mechanical classification, Mechanical separation techniques, Sedimentation (industry)

screening

The application of technical or other means which are intended to detect weapons, explosives or other dangerous devices that may be used to commit an act of unlawful inference (ICAO).
References in periodicals archive ?
The new interim guidance for using HPV DNA testing as an adjunct to cervical cytology is a more rational approach to primary cervical cancer screening, and has been derived from our growing understanding of the natural history of HPV and cervical cancer.
This study focuses on diagnosing abnormality in cervical cytology by using Pap smear test in females of reproductive, perimenopausal and menopausal age groups coming to outpatient department of our institute.
Researchers analysed results of cervical cytology from 457 317 women with a mean age of 39.
The rate of cervical cancers was the same among HPV-negative women, whether they had gone through two or three rounds of 5-year exams using both HPV testing and cervical cytology, Maaike G Dijkstra, MD, and associates, reported (BMJ.
This submission seeks approval for use of the BD Onclarity HPV assay with BD SurePath specimens for detection of 14 high-risk HPV types to determine the need for referral to colposcopy for women 21 and older with abnormal (ASC-US) Pap test results and in women 30 years and older, the use of BD Onclarity together with cervical cytology to adjunctively screen for high-risk HPV and individually identify HPV genotypes 16, 18 and 45.
Conor Kennedy, for the Nursing and Midwifery Council, said Onawelo-Mbombo studied a cervical cytology module at St Thomas' Hospital in London but failed and did not resit.
Due to various well recognised inherent limitations of cervical cytology, a percentage of high-grade lesions are missed on Pap test.
Specific entries are devoted to abdominal pain in pregnancy, BellAEs palsy in pregnancy, abnormal cervical cytology, epigastric pain, postoperative fever, and a wide variety of other related subjects.
Information about which obstetricians and gynecologists in PR are following current cervical cytology guidelines is not available.