contraction

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abbreviation

abbreviation, in writing, arbitrary shortening of a word, usually by cutting off letters from the end, as in U.S. and Gen. (General). Contraction serves the same purpose but is understood strictly to be the shortening of a word by cutting out letters in the middle, the omission sometimes being indicated by an apostrophe, as in the word don't. Most abbreviations are followed by a period. Usage, however, differs widely, and recently omission of periods has become common, as in NATO and UN. Acronyms are combinations of the first letters/syllables in a group of words to form a new grouping of letters that can be pronounced as a word. A period is never used when apostrophes appear. A list of abbreviations used in this encyclopedia may be found in the prefatory matter.

expansion

expansion, in physics, increase in volume resulting from an increase in temperature. Contraction is the reverse process. When heat is applied to a body, the rate of vibration and the distances between the molecules composing it are increased and, hence, the space occupied by the body, i.e., its volume, increases. This increase in volume is not constant for all substances for any given rise in temperature, but is a specific property of each kind of matter. For example, zinc and lead undergo greater expansion in a one-degree rise in temperature than do silver or brass. Since solids have a definite shape, each linear dimension of the solid increases by a proportional amount for a given temperature increase. The amount that a unit length along any direction of a substance increases for a temperature increase of one degree is called the coefficient of linear expansion of the substance. Most liquids also expand when heated. However, since liquids do not have a definite shape, it is the expansion of their volume as a whole that is relevant rather than the increase in a linear dimension. The amount of expansion that a unit volume (e.g., a cubic centimeter or a cubic foot) of any substance undergoes per one-degree rise in temperature is called its volume coefficient or coefficient of cubical expansion and is listed as a property of that substance. The coefficient of linear expansion can be calculated by dividing the coefficient of cubical expansion of the substance by three. When the amount of expansion of a given length of a substance has been determined experimentally, the linear coefficient is calculated by dividing the total amount of expansion by the product of the original number of length units and the number of degrees of rise in temperature. Gases also exhibit thermal expansion. The coefficient of expansion is about the same for all the common gases at ordinary temperatures; it is 1-273 of the volume at 0℃ per degree rise in temperature. The Kelvin, or absolute, scale is based upon this behavior (see Kelvin temperature scale). Charles's law concerning the expansion of gases states that the volume of a gas is directly proportional to its absolute temperature (see gas laws). Liquids differ from each other as do solids in their expansion coefficients. Water, unlike most substances, contracts rather than expands as its temperature is increased from 0℃ to 4℃; above 4℃ it exhibits normal behavior, expanding as the temperature increases.
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contraction

[kən′trak·shən]
(graphic arts)
A microfilm defect in the form of a compressed image that occurs when the film speed is reduced as the document passes through a rotary microfilmer.
(mathematics)
A function f from a metric space to itself for which there is a constant K that is less than 1 such that, for any two elements in the space, a and b, the distance between f (a) and f (b) is less than K times the distance between a and b.
(mechanics)
The action or process of becoming smaller or pressed together, as a gas on cooling.
(physiology)
Shortening of the fibers of muscle tissue.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

contraction

Of concrete, the sum of volume changes occurring as the result of all processes affecting the bulk volume of a mass of concrete.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

contraction

1. Physiol any normal shortening or tensing of an organ or part, esp of a muscle, e.g. during childbirth
2. Pathol any abnormal tightening or shrinking of an organ or part
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

contraction

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References in periodicals archive ?
Mean muscle power of triceps brachii muscle during concentric contractions using a load of 75% of the subject's 1RM in the trained and untrained groups during the drop-set (DS) and reverse drop-set (RDS) methods.
The acute exercise based on concentric contractions was the type that resulted in the highest concentrations of HSP70 in heart, kidney, gastrocnemius and soleus, but not in the lung, suggesting that metabolic stress in the former tissues was more intense at the selected time of six hours post-exercise, the optimal time-point after stress (Jing et al., 2007).
Considering that P2 consists of concentric knee extension, reduced angular velocity during the backward Fente motion (P2) appeared to be related to decreased concentric contraction of the quadriceps.
For the measurement of concentric contraction, the isokinetic concentric mode was used.
When comparing RMS values for the concentric contractions between IDC and DBC exercises, no statistical differences were observed, even when considering each phase independently (Figure 2).
Hence, in the initial downward motion, the longer eccentric contraction of hip joint extensors in elderly may increase concentric contraction of flexors at the knee joint, which would not significantly decrease angular displacement of the knee joint.
Thus, from among the five concentric contractions performed on the isokinetic dynamometer, the contraction with the highest torque was used for electromyographic analysis.
For this reason, clinicians and researchers should focus on evaluation and training of eccentric as well as concentric contractions [7,9] in musculoskeletal disorders including CAI.
Physiological costs of eccentric contraction are different from concentric contractions, because the recruitment pattern of eccentric exercise is different from that of an equivalent concentric workload [27].
This constitutes the theory of muscle movement and the physiology of concentric contractions.
The trials consisted of: 1, isometric contractions at angles of 80[degrees], 90[degrees], and 100[degrees] of plantar flexion; 2, peak torque and power at six isokinetic angular velocities at 60[degrees], 90[degrees], 120[degrees], 180[degrees], 240[degrees], and 300[degrees] per second; and 3, a fatigue test consisting of 30 maximal concentric contractions at 300[degrees] per second, where the amount of work produced and the percentage of decline in work produced was measured.
Force in eccentric contractions is generally greater than in isometric or concentric contractions (Griffin, 1987; Walmsley, Pearson, & Stymiest, 1986).