You are looking at 1-20 of 473 entries  for:

  • All: focus to skin distance x
clear all

View:

Overview

focus to skin distance

(fsd) The distance between the focal spot of the x-ray tube (where x-rays are produced) marked with a red dot on the intra-oral x-ray head to the skin surface of the patient. For ...

focus to skin distance

focus to skin distance   Quick reference

A Dictionary of Dentistry (2 ed.)

Reference type:
Subject Reference
Current Version:
2020
Subject:
Medicine and health, Dentistry
Length:
51 words

... to skin distance ( fsd ) The distance between the focal spot of the x-ray tube (where x-rays are produced) marked with a red dot on the intra-oral x-ray head to the skin surface of the patient. For the long cone paralleling technique the fsd must be at least...

focus to skin distance

focus to skin distance  

(fsd)The distance between the focal spot of the x-ray tube (where x-rays are produced) marked with a red dot on the intra-oral x-ray head to the skin surface of the patient. For the long cone ...
17 Bookbinding

17 Bookbinding   Reference library

The Oxford Companion to the Book

Reference type:
Subject Reference
Current Version:
2010
Subject:
History, Social sciences
Length:
5,252 words
Publisher:
Oxford University Press
Illustration(s):
9

...to a standard model, sometimes called flexible sewing. The basic structural features of a European bookbinding in the medieval and hand press periods. Line drawing by Chartwell Illustrators The leaves are folded into *gatherings which are sewn through the central folds on to a number of supports running horizontally across these folded edges. The projecting ends of the supports are laced and secured into stiff boards, which are then covered with an outer skin (typically leather or parchment, but possibly paper or fabric); this is decorated to create...

paralleling technique

paralleling technique  

A method of taking an intra-oral radiograph in which the film is held in a film holder parallel to the tooth and the x-ray beam is directed at 90° to the tooth and the film. A 20cm focus to skin ...
House behind the Cedars

House behind the Cedars  

Reference type:
Overview Page
Subject:
Literature
This powerful exploration of passing is both Charles Waddell Chesnutt's first novel and the first African American novel published by a major American press. Originally titled “Rena Walden,” ...
paralleling technique

paralleling technique   Quick reference

A Dictionary of Dentistry (2 ed.)

Reference type:
Subject Reference
Current Version:
2020
Subject:
Medicine and health, Dentistry
Length:
73 words

...technique A method of taking an intra-oral radiograph in which the film is held in a film holder parallel to the tooth and the x-ray beam is directed at 90° to the tooth and the film. A 20cm focus to skin distance is required to ensure that the x-ray beam is parallel rather than divergent. It gives less geometric distortion than the bisecting angle technique and allows the use of rectangular collimation...

refractive errors

refractive errors   Reference library

The Oxford Companion to the Body

Reference type:
Subject Reference
Current Version:
2003
Subject:
Science and technology, Life Sciences
Length:
1,300 words
Illustration(s):
4

...of field. Unfortunately, focusing for near objects gradually reduces with age ( presbyopia ) and has to be helped by converging or convex lenses. The lens develops from the same layer of embryonic tissue that forms the skin ( ectoderm ). Both skin and the lens grow throughout our life. Skin is slowly shed or rubbed away and replaced, but the lens is confined within the fixed volume of the eyeball. As it grows it becomes more compact and stiffer, less able to assume greater convexity for near vision. Further compaction causes opacities to develop within the lens...

Pigmentocracy

Pigmentocracy   Reference library

Ginetta E. B. Candelario

The Oxford Encyclopedia of Latinos and Latinas in Contemporary Politics, Law, and Social Movements

Reference type:
Subject Reference
Current Version:
2015
Subject:
Social sciences, Politics, Law
Length:
1,409 words

...y el problema racial en las Américas to describe the socioracial order of Latin America. A pigmentocracy refers to a hierarchy based on skin color and other bodily features considered to be racial signifiers, such as hair texture and the size and shape of noses, lips, and ears. Pigmentocracy is distinct from the “colorism” that has been documented among African Americans in the United States. Pigmentocracy refers to how society is ordered to privilege or discriminate against individuals of various phenotypes rather than to an aesthetic hierarchy within a...

Lessing, Doris

Lessing, Doris (b. 1919)   Reference library

The Oxford Encyclopedia of Women in World History

Reference type:
Subject Reference
Current Version:
2008
Subject:
History
Length:
880 words

...and injustice” (Lessing, Under My Skin , p. 262). In 1943 she met Gottfried Lessing , a German émigré and Communist intellectual, who introduced her to the inner circles of the Communist Party. The two married in 1945 and divorced amicably in 1949 . Her conquest of the literary world began soon after she and her son (by Gottfried Lessing) emigrated to England in 1949 . Before leaving Africa she had sold her first novel, The Grass Is Singing ( 1950 ), to a Johannesburg publisher. However, her London agent was able to break the earlier contract and sell...

House behind the Cedars, The

House behind the Cedars, The   Reference library

The Concise Oxford Companion to African American Literature

Reference type:
Subject Reference
Current Version:
2002
Subject:
Literature
Length:
539 words

...By showing Tryon's tragically belated determination to love Rena regardless of her race, moreover, Chesnutt demonstrates the pain that racism causes both African Americans and whites. One character whose representation has divided recent critics is Frank Fowler, the dark-skinned neighbor who loves Rena from a distance. While some have seen Frank's subservient devotions as a nod to more conventional fictions, others have read his complacent acceptance of inferiority as a sign of Chesnutt's inability to escape what may have been his own color prejudices....

Ditt and the Chuhra Mass Movement

Ditt and the Chuhra Mass Movement   Reference library

Freda Margaret Carey

The Oxford Encyclopaedia of South Asian Christianity

Reference type:
Subject Reference
Current Version:
2012

...in Christ was for the Chuhras too, he accepted Christ in June 1873 . Nattu walked a distance of 30 miles to Sialkot with him to ask the missionary Samuel Martin for baptism. Martin was unwilling to perform the baptism at first, as it went against the United Presbyterian (UP) Mission policy, but seeing Ditt's faith, and knowing that there were Biblical precedents, he finally agreed to the baptism. Ditt refused to stay at the mission station for instruction, but returned to his village and began witnessing Christ. His relatives and community ostracized him,...

Kano, Nigeria

Kano, Nigeria   Reference library

Encyclopedia of Africa

Reference type:
Subject Reference
Current Version:
2010

...long-distance and local commerce, while nearby villages produced most of the city’s food supply. After the Fulani conquest of Hausaland in the early nineteenth century, Kano became the capital of an emirate within the Sokoto Caliphate . In the twentieth century, Kano has retained a vital role in the regional economy, but through different means. Today the primary crop is peanuts, which are consumed locally and exported. The tanning and decoration of hides and skins, however, remains a major economic activity. Most contemporary residents still claim to be...

Ireland, Kevin

Ireland, Kevin   Reference library

Paul Millar

The Oxford Companion to New Zealand Literature

Reference type:
Subject Reference
Current Version:
2006
Subject:
Literature
Length:
754 words

...evocation of the cinema heroes of his childhood. Ireland's return to New Zealand was marked by Oxford University Press's publication of his Selected Poems ( 1987 ), and then a volume of finely crafted political satire: Tiberius at the Beehive ( 1990 ). Skinning a Fish ( 1994 ) is arguably Ireland's first substantial collection of poems written, as well as published, in New Zealand, to represent the full range of his verse. In comparison with the poetry written in ‘exile’, Skinning a Fish evokes a society, and a poet immersed within it. Anzac Day:...

sense organs

sense organs   Reference library

The Oxford Companion to the Body

Reference type:
Subject Reference
Current Version:
2003
Subject:
Science and technology, Life Sciences
Length:
1,196 words

...All the receptors in the skin that respond to touch and vibrations, those in muscles, tendons, and joints that detect stretch and tension, and even various receptive endings in the heart, lungs, and blood vessels that signal changes in blood pressure and inflation of the chest, are basically mechanoreceptors. Their particular sensitivities are determined by where they are placed in the body. The non-neural components of sense organs serve, then, to protect the sensory cells and also to deliver particular forms of stimulation to them. The nasal passages...

Qualitative Research on Educational Technology in Latin America

Qualitative Research on Educational Technology in Latin America   Reference library

Vani Kenski and Gilberto Lacerda Santos

The Oxford Encyclopedia of Qualitative Research Methods in Education

Reference type:
Subject Reference
Current Version:
2020
Subject:
Social sciences, Education
Length:
7,128 words
Illustration(s):
1

...and disadvantages of the pedagogical use of the media. However, the concerns of researchers in that emerging field still largely focused on programmed teaching, stemming from the theories developed by Skinner, according to which the educational process should emphasize the reproduction of previously defined knowledge. For this, students needed to actively engage with educational content and receive reinforcements for their answers to proposed questions. This closed formulation of teaching required more rigidly defined learning objectives. These new...

Adulteration

Adulteration   Reference library

Robert W. Brower

The Oxford Encyclopedia of Food and Drink in America (2 ed.)

Reference type:
Subject Reference
Current Version:
2013

...moved people from rural to urban areas, cities grew and Americans became distant from the producers and manufacturers of their food. By 1875 a national railroad system transported food from farms and ranches to centrally located urban processing locations; in turn, the railroads carried jarred, tinned, and paper-packaged food to distant consumers. America had developed a national commerce in food. The distance food traveled and the time that elapsed between production and sale created significant problems with respect to preservation. Food producers...

ageing: sensory and perceptual changes

ageing: sensory and perceptual changes   Reference library

The Oxford Companion to the Mind (2 ed.)

Reference type:
Subject Reference
Current Version:
2006
Subject:
Science and technology, Psychology, Philosophy
Length:
1,053 words
Illustration(s):
2

...differences. Most obvious is the change in ability to focus on nearby objects, and the use of reading spectacles or bifocals is commonplace. To understand the importance of this change, consider the plight of an artisan doing fine work before the advent of spectacles! Fig. 1 shows the approximate distance from the eyes of the limit of clear focus for ‘normal’ eyes—or eyes corrected to normal by spectacles—as a function of age. Other apparently ‘normal’ changes are ordinarily not so obvious to the individual. These include a reduction in resting pupil...

Dillard, Annie

Dillard, Annie (1945)   Reference library

The Encyclopedia of Religion and Nature

Reference type:
Subject Reference
Current Version:
2010
Subject:
Religion, Social sciences
Length:
869 words

...finally focuses inward, on the human observer. She makes parables of those details of weasels and eagles, and draws correspondences between human experience and the natural world, and between nature and an elusive, mysterious, divine. She had years ago opened her specimen box and saw that a carrion beetle had been for days “swimming on its pin” and Dillard transformed into incandescent prose the puzzle of suffering. Finally her beautifully constructed language silences conclusions: “But the air hardens your skin; you stand; you leave the lighted shore to explore...

Chistes

Chistes   Reference library

The Oxford Encyclopedia of Latinos and Latinas in the United States

Reference type:
Subject Reference
Current Version:
2005
Subject:
History, Regional and National History
Length:
868 words

...bridal showers or bachelor parties. In one of the least offensive of the Pepito jokes, a variant of one that focuses on the skin color of Latinas and Latinos, Pepito has died and gone to heaven. Since everyone who goes to heaven has to work, God goes up to Pepito and says, “Pepito, you are going to make babies. Here is this wheel, and every time you turn it, a baby will come out.” For hours, Pepito spins the wheel at full speed; then he starts to get tired. As he slows down, a black baby comes out. Pepito exclaims, “Damn! I better hurry because they are...

scientific photography

scientific photography   Reference library

Sidney Ray

The Oxford Companion to the Photograph

Reference type:
Subject Reference
Current Version:
2006
Subject:
Art & Architecture
Length:
1,958 words

...of the considerable distance from lens to film needed (in contrast to the very short lens to subject distance), special ‘macro’ lenses with short focus and suitable aberration correction for a particular magnification or working distance are used. Large camera formats are still popular and camera movements can be used to manipulate the vanishingly small depth of field in the subject to best advantage. Lighting may be provided by ring‐flash or fibre optic light guides, but transillumination may be the only way. Photomicrography uses transillumination for...

View: