| attraction sphere | A set of radiating microtubules extending outward from the cytocentrum and centrosphere of a dividing cell. Synonym: aster, attraction sphere, Lavdovsky's nucleoid, paranuclear body. Origin: G. Astron, star, + sphaira, ball (05 Mar 2000) |
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| sphere | 1. <geometry> A body or space contained under a single surface, which in every part is equally distant from a point within called its center. 2. Hence, any globe or globular body, especially a celestial one, as the sun, a planet, or the earth. "Of celestial bodies, first the sun, A mighty sphere, he framed." (Milton) 3. <astronomy> The apparent surface of the heavens, which is assumed to be spherical and everywhere equally distant, in which the heavenly bodies appear to have their places, and on which the various astronomical circles, as of right ascension and declination, the equator, ecliptic, etc, are conceived to be drawn; an ideal geometrical sphere, with the astronomical and geographical circles in their proper positions on it. In ancient astronomy, one of the concentric and eccentric revolving spherical transparent shells in which the stars, sun, planets, and moon were supposed to be set, and by which they were carried, in such a manner as to produce their apparent motions. 4. <logic> The extension of a general conception, or the totality of the individuals or species to which it may be applied. 5. Circuit or range of action, knowledge, or influence; compass; province; employment; place of existence. "To be called into a huge sphere, and not to be seen to move in 't." (Shak) "Taking her out of the ordinary relations with humanity, and inclosing her in a sphere by herself." (Hawthorne) "Each in his hidden sphere of joy or woe Our hermit spirits dwell." (Keble) 6. Rank; order of society; social positions. 7. An orbit, as of a star; a socket. Armillary sphere, Crystalline sphere, Oblique sphere,. See Armillary, Crystalline,. Doctrine of the sphere, applications of the principles of spherical trigonometry to the properties and relations of the circles of the sphere, and the problems connected with them, in astronomy and geography, as to the latitudes and longitudes, distance and bearing, of places on the earth, and the right ascension and declination, altitude and azimuth, rising and setting, etc, of the heavenly bodies; spherical geometry. Music of the spheres. See Music. Synonym: Globe, orb, circle. See Globe. Origin: OE. Spere, OF. Espere, F. Sphere, L. Sphaera,. Gr. A sphere, a ball. Source: Websters Dictionary (01 Mar 1998) |
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| debye sphere | <radiobiology> Sphere around a charged test particle whose radius is equal to the Debye length. (09 Oct 1997) |
| attraction | 1. <physics> An invisible power in a body by which it draws anything to itself; the power in nature acting mutually between bodies or ultimate particles, tending to draw them together, or to produce their cohesion or combination, and conversely resisting separation. Attraction is exerted at both sensible and insensible distances, and is variously denominated according to its qualities or phenomena. Under attraction at sensible distances, there are, (1) Attraction of gravitation, which acts at all distances throughout the universe, with a force proportional directly to the product of the masses of the bodies and inversely to the square of their distances apart. (2) Magnetic, diamagnetic, and electrical attraction, each of which is limited in its sensible range and is polar in its action, a property dependent on the quality or condition of matter, and not on its quantity. Under attraction at insensible distances, there are, (1) Adhesive attraction, attraction between surfaces of sensible extent, or by the medium of an intervening substance. (2) Cohesive attraction, attraction between ultimate particles, whether like or unlike, and causing simply an aggregation or a union of those particles, as in the absorption of gases by charcoal, or of oxygen by spongy platinum, or the process of solidification or crystallization. The power in adhesive attraction is strictly the same as that of cohesion. (3) Capillary attraction, attraction causing a liquid to rise, in capillary tubes or interstices, above its level outside, as in very small glass tubes, or a sponge, or any porous substance, when one end is inserted in the liquid. It is a special case of cohesive attraction. (4) Chemical attraction, or affinity, that peculiar force which causes elementary atoms, or groups of atoms, to unite to form molecules. 2. The act or property of attracting; the effect of the power or operation of attraction. 3. The power or act of alluring, drawing to, inviting, or engaging; an attractive quality; as, the attraction of beauty or eloquence. 4. That which attracts; an attractive object or feature. Synonym: Allurement, enticement, charm. Origin: L. Attractio: cf. F. Attraction. Source: Websters Dictionary (01 Mar 1998) |
| capillary attraction | The force that causes fluids to rise up very fine tubes or through the pores of a loose material. (05 Mar 2000) |
| van der Waals attraction | <chemistry> Electrodynamic forces arise between atoms, molecules and assemblies of molecules due to their vibrations giving rise to electromagnetic interactions, these are attractive when the vibrational frequencies and absorptions are identical or similar, repulsive when nonidentical. Other interactions originally proposed by van der Waals were included in this name, but these are usually separated into the Coulomb's force, the Keesom force and the London force. Only the last is of electrodynamic nature. Probably important in holding lipid membranes into that structure and possibly in other interactions, for example cell adhesion. Electrodynamic forces between large scale assemblies can be of relatively long range nature. (18 Nov 1997) |
| magnetic attraction | The force that draws iron or steel toward a magnet. (05 Mar 2000) |
| chemical attraction | The force impelling atoms of different elements or molecules to unite to form new substances or compounds. (05 Mar 2000) |
| neurotropic attraction | The pull of a regenerating axon toward the motor end-plate. (05 Mar 2000) |
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