atomic mass unit

unit (u´nit)

1. a single thing.

2. a quantity assumed as a standard of measurement. Symbol U.

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Angström unit  angstrom.

atomic mass unit  (u) (amu) the unit mass equal to 112 the mass of the nuclide of carbon-12. Called also dalton.

Bethesda unit  a measure of the level of inhibitor to coagulation factor VIII; equal to the amount of inhibitor in patient plasma that will inactivate 50 per cent of factor VIII in an equal volume of normal plasma following a 2-hour incubation period.

Bodansky unit  the quantity of alkaline phosphatase that liberates 1 mg of phosphate ion from glycerol 2-phosphate in 1 hour under standard conditions.

British thermal unit  (BTU) the amount of heat necessary to raise the temperature of one pound of water one degree Fahrenheit, usually from 39°F to 40°F.

CGS unit  any unit in the centimeter-gram-second system.

CH50 unit  the amount of complement that will lyse 50 per cent of a standard preparation of sheep red blood cells coated with antisheep erythrocyte antibody.

coronary care unit  a specially designed and equipped hospital area containing a small number of private rooms, with all facilities necessary for constant observation and possible emergency treatment of patients with severe heart disease.

intensive care unit  a hospital unit in which are concentrated special equipment and skilled personnel for the care of seriously ill patients requiring immediate and continuous attention; abbreviated ICU.

International unit  (IU) a unit of biological material, as of enzymes, hormones, vitamins, etc., established by the International Conference for the Unification of Formulas.

motor unit  the unit of motor activity formed by a motor nerve cell and its many innervated muscle fibers.

SI unit  any of the units of the Système International d'Unités (International System of Units) adopted in 1960 at the Eleventh General Conference of Weights and Measures.

Somogyi unit  that amount of amylase which will liberate reducing equivalents equal to 1 mg of glucose per 30 minutes under defined conditions.

Svedberg unit  (S) a unit equal to 10−13 second used for expressing sedimentation coefficients of macromolecules.

terminal respiratory unit  the anatomical and functional unit of the lung, including a respiratory bronchiole, alveolar ducts and sacs, and alveoli.

toxic unit , toxin unit the smallest dose of a toxin which will kill a guinea pig weighing about 250 gm in three to four days.

USP unit  one used in the United States Pharmacopeia in expressing potency of drugs and other preparations.

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atomic mass unit

n. Abbr. amu

A unit of mass equal to ¹/₁₂ the mass of an atom of carbon 12, which is assigned a mass of 12. Also called dalton.

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atomic mass unit (amu)

[ətom′ik]

the mass of a neutral atom of an element, expressed as ¹⁄₁₂ of the mass of the isotope carbon-12, which has a value of exactly 12. The energy equivalent of 1 amu is 931.2 MeV. The mass equivalent of 1 amu is 1.66 (10^-24 g).

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unit [u´nit]

1. a single thing; one segment of a whole that is made up of identical or similar segments.

2. a specifically defined amount of anything subject to measurement, as of activity, dimension, velocity, volume, or the like.

3. a distinct part of a hospital, usually having a specific physical location and serving a defined function; see under names of specific units.

Ångström unit angstrom.

atomic mass unit (u) (amu) the unit of mass equal to ¹⁄₁₂ the mass of the nuclide of carbon 12. Called also dalton.

autonomous nursing unit a nursing unit under a decentralized administration system in which the staff is responsible for all aspects of unit functioning.

British thermal unit (BTU) a unit of heat formerly widely used, being the amount necessary to raise the temperature of 1 pound of water from 39° to 40°F., equal to approximately 252 calories.

CH50 unit the amount of complement that will lyse 50 per cent of a standard preparation of sheep red blood cells coated with antisheep erythrocyte antibody.

continuing education unit (CEU) a unit of credit for educational offerings given to professional persons, determined by a professional organization according to a mathematical formula after a thorough review of the program of study, the qualifications of the instructors, and the program objectives.

critical care unit intensive care unit.

electrostatic u's (esu) that system of units that is based on the fundamental definition of a unit charge as one that will repel a similar charge with a force of 1 dyne when the two charges are 1 cm apart in a vacuum.

environmental control unit a computerized system that allows the handicapped individual to operate several different appliances using a keyboard or other input device.

heat unit the amount of heat energy that is produced by one kVp (kilovolt peak) and one mA (milliampere) for one second with single phase, full wave rectified radiographic equipment.

Hounsfield unit an arbitrary unit of x-ray attenuation used for CT scans. Each voxel is assigned a value on a scale in which air has a value of −1000; water, 0; and compact bone, +1000.

intensive care unit see intensive care unit.

International unit (IU)

1. a unit of enzyme activity equal to the amount of enzyme that catalyzes the conversion of one micromole of substrate or coenzyme per minute under specified conditions (temperature, pH, and substrate concentration) of the assay method. Abbreviated U.

2. any of several arbitrary units that have been adopted by international bodies to express the quantities of certain vitamins (A, C, D, and thiamine hydrochloride), hormones (androgen, chorionic gonadotropin, estradiol benzoate, estrone, insulin, progesterone, and prolactin), and drugs (digitalis and penicillin).

Kienböck's unit a unit of x-ray exposure equal to 0.1 erythema dose; symbol X.

motor unit the unit of motor activity formed by a motor nerve cell and its many innervated muscle fibers.

postanesthesia care unit (PACU) a specialty unit in a hospital for giving postanesthesia care (care of patients recovering from anesthesia and intravenous sedation); formerly called recovery room.

radiologic u's units used to measure radiation, including roentgens, rads, rems, and curies.

u's of service (UOS)

1. the number of procedures done by a department.

2. individuals or groups of individuals who are the recipients of nursing care.

short procedures unit (short term care unit) a nursing unit where patients are briefly cared for following a medical or surgical procedure and are then discharged without spending the night.

SI unit any unit of the International System of units (the metric system); see also si units.

step-down unit a nursing unit designated to provide care for patients who are stable enough to be discharged from the intensive care unit but are not yet ready to be cared for on a medical-surgical unit.

Svedberg unit (S) a unit equal to 10⁻¹³ second used for expressing sedimentation coefficients of macromolecules.

Svedberg flotation unit (S_f) a unit equal to 10⁻¹³ second used for expressing negative sedimentation coefficients of macromolecules that float rather than sink in a centrifuge, e.g., lipoproteins.

terminal respiratory unit the functional unit of the lung, including a respiratory bronchiole, alveolar ducts and sacs, and alveoli; called also primary lobule of lung and primary respiratory lobule.

USP unit one used in the United States Pharmacopeia for expressing potency of drugs and other preparations.

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unit

1. a single thing; one segment of a whole that is made up of identical or similar segments.

2. a specifically defined amount of anything subject to measurement, as of activity, dimension, velocity, volume, or the like.

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Angstrom unit

see angstrom.

atomic mass unit

see dalton.

International unit

1. see si units.

2. a unit of enzyme activity equal to the amount of enzyme that catalyzes the conversion of one micromole of substrate or coenzyme per minute under specified conditions (temperature, pH and substrate concentration) of the assay method. Abbreviated U.

3. any of several arbitrary units that have been adopted by international bodies to express the quantities of certain vitamins (A, C, D and thiamin hydrochloride), hormones (androgen, chorionic gonadotropin, estradiol benzoate, estrone, insulin, progesterone and prolactin), and drugs (digitalis and penicillin).

SI unit

any unit of the International System of units (the metric system). See si units.