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gray

 
also grey (grā) pronunciation
adj., gray·er, also grey·er, gray·est, grey·est.
  1. Of or relating to an achromatic color of any lightness between the extremes of black and white.
    1. Dull or dark: a gray, rainy afternoon.
    2. Lacking in cheer; gloomy: a gray mood.
    1. Having gray hair; hoary.
    2. Old or venerable.
  2. Intermediate in character or position, as with regard to a subjective matter: the gray area between their differing opinions on the film's morality.
n.
  1. An achromatic color of any lightness between the extremes of black and white.
  2. An object or animal of the color gray.
  3. often Gray
    1. A member of the Confederate Army in the Civil War.
    2. The Confederate Army.

v., grayed, also greyed, gray·ing, grey·ing, grays, greys.

v.tr.
To make gray.

v.intr.
  1. To become gray.
    1. To become old; age.
    2. To include a large or increasing proportion of older people: "Federal food programs can't keep up with the nation's rapidly graying population" (Michael J. McCarthy).

[Middle English grei, from Old English grǣg.]

grayly gray'ly adj.
grayness gray'ness n.

gray2 (grā) pronunciation
n. (Abbr. Gy)
The SI unit for the energy absorbed from ionizing radiation, equal to one joule per kilogram.

[After Louis Harold Gray (1905-1965), British radiobiologist.]


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is a common American English variant of grey.

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Symbol Gy. The derived SI unit of absorbed dose of ionizing radiation (see radiation units). It is named after the British radiobiologist L. H. Gray (1905–65).



[Etymology: L. H. Gray; UK 1905-65] radiation physics. Symbol Gy. SI The derived unit for absorbed dose of ionizing radiation, specific energy imparted, kerma, absorbed dose index, being energy imparted to a dosed material per unit mass, identically J·kg-1 (= m2·s-2 in base terms). Hence
Gy·s-1 for absorbed dose rate.Though the effect of any radiation depends on its amount of energy, it also depends on the type of radiation and on the energy levels of particular particles. The effect on biological tissue depends on the type of tissue and other factors; the unit applying to the net effect is the sievert. The sievert is dimensionally identical with the gray, but the two are distinct as regards context, i.e. the gray should be used only for absorbed dose, the sievert only for dose equivalent. Otherwise, it is accepted that the gray can be used, within the field of ionizing radiations, with other physical quantities also expressed in joules per kilogram.

The gray was defined only by the 15th CGPM of 1975, to succeed the rad as the measure of absorbed dose; 1 Gy = 100 rad.

197515th CGPM: re ionizing radiations ‘adopts the following special name for the SI unit of ionizing radiation: gray, symbol Gy, equal to one joule per kilogram.
Note. - The gray is the SI unit of absorbed dose. In the field of ionizing radiation the gray may also be used with other physical quantities also expressed in joules per kilogram.’see note below

[Le Système International d'Unités (Sèvres, France: Bureau International de Poids et Mesures, 1985)]

(1810–1888)

The leading American botanist of the 19th century. As professor of natural history at Harvard from 1842, he taught many who became eminent botanists, and he popularized the subject through his articles and textbooks.

Word Tutor:

grayed

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pronunciation

IN BRIEF: adj. - Deprived of color.

Tutor's tip: The beauty school student received a failing "grade" (a mark indicating a level of accomplishment) when she "grayed" (to have made gray) her model's blonde hair.

LearnThatWord.com is a free vocabulary and spelling program where you only pay for results!

as in: the color
sign description: Both open hands brush back and forth by one another.




noun
noun

1:
A white-skinned person. (1960 —) .
O. Harrington The year was 1936, a bad year in most everybody's book. Ellis the cabdriver used to say that even the grays downtown were having it rough (1965). adjective

2:
Of a person: white-skinned. (1962 —) .
E. Lacy Funny thing with grey chicks....They're always so sure their white skin is the sexiest ever (1965).



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symbol: Gy; the SI derived unit of absorbed dose of radiation, equal to one joule per kilogram of living tissue;
1 Gy = 1 Jkg−1 = 1 m2s−2
. Compare sievert. See also rad. [After Louis Harold Gray (1905 — 65), British physicist and radiobiologist.]

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Gray (unit)

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The gray (symbol: Gy) is the SI unit of absorbed radiation dose of ionizing radiation (for example, X-rays), and is defined as the absorption of one joule of ionizing radiation by one kilogram of matter (usually human tissue).[1]

Named after the British physicist Louis Harold Gray, the SI unit replaces the traditional cgs unit, the rad (equivalent to 0.01 Gy), which remains common in industry in the United States, while "strongly discouraged" in the style guide for U.S. National Institute of Standards and Technology authors.[2]

Contents

Definition

One gray is the absorption of one joule of energy, in the form of ionizing radiation, divided by one kilogram of matter.

1 \ \mathrm{Gy} = 1\ \frac{\mathrm{J}}{\mathrm{kg}} = 1\ \mathrm{m}^2\cdot\mathrm{s}^{-2}

For xrays and gamma rays, these are the same units as the sievert (Sv). To avoid any risk of confusion between the absorbed dose (by matter) and the equivalent dose (by biological tissues), one must use the corresponding special units, gray is used instead of the joule per kilogram for absorbed dose and the sievert instead of the joule per kilogram for the dose equivalent. The word "gray" is both the singular and plural spelling.

This SI unit is named after Louis Harold Gray. As with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is upper case (Gy). When an SI unit is spelled out in English, it should always begin with a lower case letter (gray), except where any word would be capitalized, such as at the beginning of a sentence or in capitalized material such as a title. Note that "degree Celsius" conforms to this rule because the "d" is lowercase. —Based on The International System of Units, section 5.2. The gray was defined in 1975 in honour of Louis Harold Gray (1905–1965), who used a similar concept, "that amount of neutron radiation which produces an increment of energy in unit volume of tissue equal to the increment of energy produced in unit volume of water by one röntgen of radiation," in 1940.

Effect on the body

The gray measures the deposited energy of radiation. The biological effects vary by the type and energy of the radiation and the organism and tissues involved. The sievert attempts to account for these variations.

A whole-body exposure to 5 or more gray of high-energy radiation at one time usually leads to death within 14 days. This dosage represents 375 joules for a 75 kg adult (equivalent to the chemical energy in 20 mg of sugar). Since gray are such large amounts of radiation, medical use of radiation is typically measured in milligray (mGy).

As experienced from follow-up after radiation therapy, epilation may occur on any hair-bearing skin with doses above 1 Gy. It occurs only within the radiation field/s. Hair loss may be permanent with a single dose of 10 Gy, but if the dose is fractionated permanent hair loss may not occur until dose exceeds 45 Gy. The salivary glands and tear glands have a radiation tolerance of about 30 Gy in 2 Gy fractions, a dose which is exceeded by most radical head and neck cancer treatments, potentially causing dryness. Dry mouth (xerostomia) and dry eyes (xerophthalmia) can become irritating long-term problems and severely reduce the patient's quality of life. Similarly, sweat glands in treated skin (such as the armpit) tend to stop working, and the naturally moist vaginal mucosa is often dry following pelvic irradiation.

Dangerously high doses of radiation received by a fetus during the first trimester primarily affect its heart and limbs, while later in pregnancy the brain is the major affected site.[3]

Dose by source

In radiation therapy, the amount of radiation varies depending on the type and stage of cancer being treated. For curative cases, the typical dose for a solid epithelial tumor ranges from 60 to 80 Gy, while lymphomas are treated with 20 to 40 Gy. Preventive (adjuvant) doses are typically around 45–60 Gy in 1.8–2 Gy fractions (for breast, head, and neck cancers).

The average radiation dose from an abdominal X-ray is 1.4 mGy, that from an abdominal CT scan is 8.0 mGy, that from a pelvic CT scan is 25 mGy, and that from a selective CT scan of the abdomen and the pelvis is 30 mGy.[4]

Roentgen

The roentgen is defined as the radiation exposure equal to the quantity of ionizing radiation that will produce one esu of charge in one cubic centimetre of dry air at 0 °C and a standard atmosphere, and is conventionally taken to be worth 0.258 mC/kg (using a conventional air density of about 1.293 kg/m3). Using an air ionization energy of about 35 J/C, we have 1 Gy ≈ 111 R.

See also

References

  1. ^ "The International System of Units (SI)". Bureau International des Poids et Mesures (BIPM). http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf. Retrieved 2010-01-31. 
  2. ^ "NIST Guide to SI Units - Units temporarily accepted for use with the SI". http://physics.nist.gov/Pubs/SP811/sec05.html#5.2. 
  3. ^ medscape.com >What Risk Dose X-Ray Pose to Fetus? From USMLEasy from McGraw-Hill. Posted: 09/16/2010.
  4. ^ Baden, Jeffrey M.; Jay B. Brodsky (1985). The Pregnant surgical patient. London: Futura. ISBN 0-87993-238-4. [page needed]

Translations:

Grey

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Dansk (Danish)
adj. - grå, gråhåret, ældet
n. - gråt, ubleget stof el. garn
v. tr. - male grå
v. intr. - blive grå, gråne, ældes

idioms:

  • grey area    gråt område, økonomisk tilbagestillet område
  • grey matter    hjerneceller, grå substans

Nederlands (Dutch)
grijs, grauw, somber, anoniem, saai, grauw licht, schimmel (paard), grijze kleding, grijs maken, vergrijzen

Français (French)
adj. - gris, grisonnant, morne (une vie), terne (un caractère) (péj)
n. - gris, cheval gris
v. tr. - vieillir, grisonner
v. intr. - vieillir, grisonner

idioms:

  • grey area    zone floue
  • grey matter    matière grise

Deutsch (German)
adj. - grau, gesichtslos
n. - Grau, Schimmel
v. - ergrauen

idioms:

  • grey area    Grauzone
  • grey matter    graue Substanz, graue Zellen

Ελληνική (Greek)
adj. - φαιός, γκρίζος, γκρι, σταχτής, ψαρός, (μτφ.) μουντός, σκοτεινός
n. - γκρι, γκρίζο, γκρίζα ρούχα, (άλογο) ψαρής, μουντό φως
v. - (για μαλλιά) γκριζάρω

idioms:

  • grey area    γκρίζα περιοχή/ζώνη, περιοχή με υψηλό ποσοστό ανεργίας
  • grey matter    φαιά ουσία (του εγκεφάλου)

Italiano (Italian)
incanutire, cavallo grigio, grigio

idioms:

  • grey area    poco chiaro
  • grey matter    materia grigia

Português (Portuguese)
adj. - cinza, sombrio, grisalho, maduro
n. - cor (f) cinza, traje (m) cinzento, pano (m) cru
v. - acinzentar, tornar grisalho

idioms:

  • grey area    área (f) nebulosa, área (f) onde o desemprego é alto
  • grey matter    massa (f) cinzenta (Anat.), inteligência (f) (fig.)

Русский (Russian)
серый цвет, серый, седой, мрачный

idioms:

  • grey area    нечто среднее, "серая зона"
  • grey matter    серое вещество головного мозга, умственные способности

Español (Spanish)
adj. - gris, cano, crudo, nublado, triste, oscuro, aburrido, relativo a la vejez o ancianidad
n. - caballo blanco, rucio, gris (color), cualquier cosa de ese color
v. tr. - encanecer, envejecer, ponerse cano, volver de color gris
v. intr. - encanecer, envejecer, ponerse cano, triste, volver de color gris

idioms:

  • grey area    zona gris, terreno poco definido, zona intermedia
  • grey matter    materia gris, seso

Svenska (Swedish)
adj. - grå, grånad, kulen, dyster
n. - grått, grå färg, dämpat ljus, grålle
v. - göra grå, bli grå

中文(简体)(Chinese (Simplified))
灰色的, 阴沉的, 灰色, 使成为灰色, 使变老, 成为灰色或灰白, 发生人口老化

idioms:

  • grey area    灰色区, 指介于两个对立面之间的范畴
  • grey matter    灰白质, 头脑, 智力

中文(繁體)(Chinese (Traditional))
adj. - 灰色的, 陰沈的
n. - 灰色
v. tr. - 使成為灰色, 使變老
v. intr. - 成為灰色或灰白, 發生人口老化

idioms:

  • grey area    灰色區, 指介於兩個對立面之間的範疇
  • grey matter    灰白質, 頭腦, 智力

한국어 (Korean)
adj. - 회색의, 노년의, 우중충한, 암울한, 경험 많은
n. - 회색, 회색 군복, 중년 남자, 회색의 것
v. tr. - 백발이 되게 하다, 회색으로 만들다, 광택을 없애다
v. intr. - 회색이 되다, 백발이 되다

日本語 (Japanese)
adj. - 灰色, 灰色になる, つや消しにする, 葦毛の馬, 灰色の, 青い, 曇った, うす暗い, 白髪まじりの

idioms:

  • grey area    灰色地帯
  • grey matter    灰白質, 頭脳

العربيه (Arabic)
‏(صفه) رمادي, أشيب (الاسم) اللون الرمادي (فعل) يجعله رماديا‏

עברית (Hebrew)
adj. - ‮אפור, קודר, דהה, מדוכא, מדכא, ששערו אפור‬
n. - ‮צבע אפור, חומר אפור או בגדים אפורים, אור שמש חיוור, סוס אפור או לבן‬
v. tr. - ‮עשה לאפור‬
v. intr. - ‮האפיר‬


 
 

 

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