| Parallel Electron Energy Loss Spectroscopy | <technique> Electron energy loss spectroscopy analyses the inelastically scattered electrons present in the beam after it has been transmitted through the sample. An electron energy loss spectrum typically consists of a monatomic decreasing background on which are superimposed a number of peaks. Each peak is characteristic of the scattering process that has occurred in the sample. The peaks can be used to obtain information about the chemical composition and electronic structure of the sample. Electron energy loss spectra are acquired typically in a magnetic sector spectrometer located under the camera chamber of the transmission electron microscope. Spatial resolution is typically limited by the minimum probe diameter of the microscope. Electron energy loss spectroscopy tends to be complimentary to EDS in that it can be used to analyse very thin samples of low Z materials. Acronym: PEELS (05 Aug 1998) |
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| parallel rays | Ray's parallel to the axis of an optical system. (05 Mar 2000) |
| parallel track | <pharmacology> A system for distributing certain experimental drugs to people who are unable to participate in ongoing clinical trials. (09 Oct 1997) |
| parallelism | 1. The state of being structurally parallel. 2. In psychology, the mind-body doctrine that for every conscious process there is a corresponding or parallel organic process, without asserting a causal interrelation between the two. Origin: para-+ G. Allelon, of one another, fr. Allos, other (05 Mar 2000) |
| parallelogram | <geometry> A right-lined quadrilateral figure, whose opposite sides are parallel, and consequently equal; sometimes restricted in popular usage to a rectangle, or quadrilateral figure which is longer than it is broad, and with right angles. Parallelogram of velocities, forces, accelerations, momenta, etc. <mechanics> A parallelogram the diagonal of which represents the resultant of two velocities, forces, accelerations, momenta, etc, both in quantity and direction, when the velocities, forces, accelerations, momenta, etc, are represented in quantity and direction by the two adjacent sides of the parallelogram. Origin: Gr.; parallel + to write: cf. F. Parallelogramme. See Parallel, and -gram. Source: Websters Dictionary (01 Mar 1998) |
| parallelometer | An apparatus used for paralleling the attachments and abutments for fixed or removable partial dentures. (05 Mar 2000) |
| parallelopiped | <geometry> A solid, the faces of which are six parallelograms, the opposite pairs being parallel, and equal to each other; a prism whose base is a parallelogram. Origin: Gr. A body with parallel surfaces; parallel + a plane surface, on the ground, or level with it, level, flat; on + the ground: cf. F. Parallelopipede. Source: Websters Dictionary (01 Mar 1998) |
| parallergic | Denoting an allergic state in which the body becomes predisposed to non-specific stimuli following original sensitization with a specific allergen. (05 Mar 2000) |
| paralogia | False reasoning, involving self-deception. Origin: G. Paralogia, a fallacy, fr. Para, beside, + logos, reason Thematic paralogia, false reasoning in relation chiefly to one theme or subject, upon which the mind dwells insistently. (05 Mar 2000) |
| paraluteal cell | A steroid secretory cell of the corpus luteum that comes from the theca interna of the ovarian follicle at the time of ovulation. Synonym: paraluteal cell, paralutein cell. (05 Mar 2000) |
| paralutein cell | A steroid secretory cell of the corpus luteum that comes from the theca interna of the ovarian follicle at the time of ovulation. Synonym: paraluteal cell, paralutein cell. (05 Mar 2000) |
| paralysis | <neurology> Loss or impairment of motor function in a part due to lesion of the neural or muscular mechanism, also by analogy, impairment of sensory function (sensory paralysis). In addition to the types named below, paralysis is further distinguished as traumatic, syphilitic, toxic, etc., according to its cause or as obturator, ulnar, etc., according to the nerve part or muscle specially affected. Origin: Gr. Lyein = to loosen (18 Nov 1997) |
| paralysis agitans | An obsolete term for parkinsonism. (05 Mar 2000) |
| paralysis, bulbar | A paralysis resulting from changes in the motor centres of the medulla oblongata. It is chronic, usually fatal, and most commonly occurring in persons over 50 years old. (12 Dec 1998) |
| paralysis, familial periodic | An autosomal dominant trait marked by recurring attacks of rapidly progressive flaccid paralysis. There are three types: I, associated with a fall in serum potassium levels (hypokalaemic periodic paralysis); II, associated with a rise therein (hyperkalaemic periodic paralysis, called also adynamia episodica hereditaria); and III, with normal levels (normokalaemic periodic paralysis). (12 Dec 1998) |