| accumulating shear | A feller-buncher shearhead that is capable of accumulating and holding 2 or more cut stems. (05 Dec 1998) |
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| shear | 1. To cut, clip, or sever anything from with shears or a like instrument; as, to shear sheep; to shear cloth. It is especially applied to the cutting of wool from sheep or their skins, and the nap from cloth. 2. To separate or sever with shears or a similar instrument; to cut off; to clip (something) from a surface; as, to shear a fleece. "Before the golden tresses . . . Were shorn away." (Shak) 3. To reap, as grain. 4. To deprive of property; to fleece. 5. <mechanics> To produce a change of shape in by a shear. See Shear. Origin: Sheared or Shore; Sheared or Shorn; Shearing] [OE. Sheren, scheren, to shear, cut, shave, AS. Sceran, scieran, scyran; akin to D. & G. Scheren, Icel. Skera, Dan. Skire, Gr. Cf. Jeer, Score, Shard, Share, Sheer to turn aside. 1. A pair of shears; now always used in the plural, but formerly also in the singular. See Shears. "On his head came razor none, nor shear." (Chaucer) "Short of the wool, and naked from the shear." (Dryden) 2. A shearing; used in designating the age of sheep. "After the second shearing, he is a two-sher ram; . . . at the expiration of another year, he is a three-shear ram; the name always taking its date from the time of shearing." (Youatt) 3. <engineering> An action, resulting from applied forces, which tends to cause two contiguous parts of a body to slide relatively to each other in a direction parallel to their plane of contact; also called shearing stress, and tangential stress. 4. <mechanics> A strain, or change of shape, of an elastic body, consisting of an extension in one direction, an equal compression in a perpendicular direction, with an unchanged magnitude in the third direction. Shear blade, one of the blades of shears or a shearing machine. Shear hulk. See Hulk. Shear steel, a steel suitable for shears, scythes, and other cutting instruments, prepared from fagots of blistered steel by repeated heating, rolling, and tilting, to increase its malleability and fineness of texture. Origin: AS. Sceara. See Shear. Source: Websters Dictionary (01 Mar 1998) |
| shear fields | <radiobiology> As used in plasma physics, this refers to magnetic fields having a rotational transform (or, alternatively, safety factor) that changes with radius (for example, in the stellarator concept, magnetic fields that increase in pitch with distance from the magnetic axis.) (09 Oct 1997) |
| shear flow | A flow of a material in which parallel planes in the material are displaced in a direction parallel to each other. (05 Mar 2000) |
| shear rate | The change in velocity of parallel planes in a flowing fluid separated by unit distance; its units expressed in seconds-1. (05 Mar 2000) |
| shear stress | The force acting in shear flow expressed per unit area; units in the CGS system: dynes/cm2. (05 Mar 2000) |
| atrioventricular gradient | The diastolic pressure difference between the atrium and ventricle. (05 Mar 2000) |
| magnetic field gradient | In magnetic resonance imaging, a magnetic field that varies with location, superimposed on the uniform field of the magnet, to alter the resonant frequency of nuclei and allow recovery of their spatial position. Synonym: field gradient. (05 Mar 2000) |
| ventricular gradient | The algebraic sum of (i.e., the net electrical difference between) the area enclosed within the QRS complex and that within the T wave in the electrocardiogram. (05 Mar 2000) |
| voltage gradient | <physiology> Literally, the electric field in a region, defined as the potential difference between two points divided by the distance between them. Used more loosely, the potential difference across a plasma membrane. (18 Nov 1997) |
| centrifugation, density gradient | Separation of particles according to density by employing a gradient of varying densities. at equilibrium each particle settles in the gradient at a point equal to its density. (12 Dec 1998) |
| cesium chloride gradient centrifugation | A type of density gradient centrifugation, a lab technique used to separate or purify nucleic acids. It involves putting cesium chloride and the nucleic acids into a centrifuge to be spun for hours or days. The cesium chloride forms a density gradient (highly dense at the bottom, thinnest at the top), and the different nucleic acids separate along the gradient according to their buoyancies in different densities. (09 Oct 1997) |
| gradient | <physics> Mathematical term for the operator which determines the magnitude and direction of the greatest rate-of-change of a given function with position. Similarly used to describe such a rate-of-change. For instance, at a given point on a hill, the slope of the hill in the steepest uphill direction is the gradient of the altitude function for the hill. (09 Oct 1997) |
| gradient elution | Elution in column chromatography in which a changing pH or ionic strength is used to separate substances. (05 Mar 2000) |
| gradient encoding | In magnetic resonance imaging, the technique of inducing a gradient in the magnetic field in the Y-axis to induce phase differences with location. Synonym: gradient encoding. (05 Mar 2000) |