| ELS | Eaton-Lambert syndrome; electron loss spectroscopy; extended least square; extracorporeal life suppo... |
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| LCF | least common factor; lymphocyte culture fluid |
| LFD | lactose-free diet; large for date [fetus]; late fetal death; lateral facial dysplasia; least fatal d... |
| LNLS | linear-nonlinear least squares |
| LSB | least significant bit; left sternal border; left scapular border; long spike burst |
| Bernoulli's principle | <physics> When friction is negligible, the velocity of flow of a gas or fluid through a tube is inversely related to its pressure against the side of the tube; i.e., velocity is greatest and pressure lowest at a point of constriction. Synonym: Bernoulli's principle, Bernoulli's theorem. (05 Mar 2000) |
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| pain-pleasure principle | A psychoanalytic concept that, in a human's psychic functioning, he/she tends to seek pleasure and avoid pain; a term borrowed by experimental psychology to denote the same tendency of an animal in a learning situation. Synonym: pleasure principle. (05 Mar 2000) |
| reality principle | The concept that the pleasure principle in personality development is modified by the demands of external reality; the principle or force that compels the growing child to adapt to the demands of external reality. (05 Mar 2000) |
| Pauli's exclusion principle | The theory limiting the number of electrons in the orbit or shell of an atom; that it is not possible for any two electrons to have all four quantum numbers identical. (05 Mar 2000) |
| repetition-compulsion principle | In psychoanalysis, the impulse to redramatise or reenact earlier emotional experiences or situations. Synonym: principle of inertia. (05 Mar 2000) |
| melanophore-expanding principle | A polypeptide hormone secreted by the intermediate lobe of the hypophysis in humans (in neurohypophysis in certain other species) which causes dispersion of melanin by melanophores, resulting in darkening of the skin, presumably by promoting melanin synthesis; this effect is readily demonstated in some lower vertebrates, such as frogs and fish; alpha-melanotropin is an N-acetylated peptide with 13 amino acids; beta-melanotropin has 22 amino acids. Synonym: intermedin, melanocyte-stimulating hormone, melanophore-expanding principle. (05 Mar 2000) |
| Mitrofanoff principle | Use of an isolated appendix on a vascularised pedicle as a catheterizable route of access to the bladder from the skin. Synonym: Mitrofanoff principle. Origin: eppendico-+ L. Vesica, bladder, + G. Stoma, mouth (05 Mar 2000) |
| closure principle | In psychology, the principle that when one views fragmentary stimuli forming a nearly complete figure (e.g., an incomplete rectangle) one tends to ignore the missing parts and perceive the figure as whole. See: gestalt. (05 Mar 2000) |
| pleasure-pain principle | The psychoanalytic concept that man instinctively seeks to avoid pain and discomfort and strives for gratification and pleasure. (12 Dec 1998) |
| pleasure principle | A psychoanalytic concept that, in a human's psychic functioning, he/she tends to seek pleasure and avoid pain; a term borrowed by experimental psychology to denote the same tendency of an animal in a learning situation. Synonym: pleasure principle. (05 Mar 2000) |
| consistency principle | In psychology, the desire of the human being to be consistent, especially in his attitudes and beliefs; theories of attitude formation and change based on the consistency principle include balance theory, which suggests that the individual seeks to avoid incongruity in his various attitudes. See: cognitive dissonance theory. (05 Mar 2000) |
| haematinic principle | The principle previously thought to be produced by the action of Castle's intrinsic factor upon an extrinsic factor in food, now recognised as vitamin B12. (05 Mar 2000) |
| principle | 1. Beginning; commencement. "Doubting sad end of principle unsound." (Spenser) 2. A source, or origin; that from which anything proceeds; fundamental substance or energy; primordial substance; ultimate element, or cause. "The soul of man is an active principle." (Tillotson) 3. An original faculty or endowment. "Nature in your principles hath set [benignity]" (Chaucer) "Those active principles whose direct and ultimate object is the communication either of enjoyment or suffering." (Stewart) 4. A fundamental truth; a comprehensive law or doctrine, from which others are derived, or on which others are founded; a general truth; an elementary proposition; a maxim; an axiom; a postulate. "Therefore, leaving the principles of the doctrine of Christ, let us go on unto perfection." (Heb. Vi. 1) "A good principle, not rightly understood, may prove as hurtful as a bad." (Milton) 5. A settled rule of action; a governing law of conduct; an opinion or belief which exercises a directing influence on the life and behavior; a rule (usually, a right rule) of conduct consistently directing one's actions; as, a person of no principle. "All kinds of dishonesty destroy our pretenses to an honest principle of mind." (Law) 6. <chemistry> Any original inherent constituent which characterises a substance, or gives it its essential properties, and which can usually be separated by analysis; applied especially to drugs, plant extracts, etc. "Cathartine is the bitter, purgative principle of senna." (Gregory) Bitter principle, Principle of contradiction, etc. See Bitter, Contradiction, etc. Origin: F. Principe, L. Principium beginning, foundation, fr. Princeps, -cipis. See Prince. Source: Websters Dictionary (01 Mar 1998) |
| principle of inertia | In psychoanalysis, the impulse to redramatise or reenact earlier emotional experiences or situations. Synonym: principle of inertia. (05 Mar 2000) |
| proximate principle | In chemistry, an organic compound that may exist already formed as a part of some other more complex substance (e.g., various sugars, starches, and albumins). Synonym: organic principle. (05 Mar 2000) |