| angle of refraction | <optics> The angle that a ray leaving a refracting medium makes with a line drawn perpendicular to the surface of this medium. (05 Mar 2000) |
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| refraction | <physics> Bending of waves as they pass from a medium having one refractive index to a medium (or region within a medium) having a different refractive index. (09 Oct 1997) |
| refraction, angle of | <microscopy> The acute angle between the normal to a refracting surface at the point of incidence, and the refracted ray. (05 Aug 1998) |
| refraction, ocular | Refraction of light effected by the media of the eye. It also includes the determination of the refractive state and refractive correction. (12 Dec 1998) |
| static refraction | Refraction without accommodation. (05 Mar 2000) |
| double refraction | <microscopy> The refraction of light in two slightly different directions to form two rays or vector components. Each ray is polarized, and their vibration directions are perpendicular to each other. Furthermore, each ray has a different velocity, and therefore a different refractive index. See: birefringence. (05 Aug 1998) |
| dynamic refraction | Refraction of the eye during accommodation. (05 Mar 2000) |
| index of refraction | <physics> For a given wavelength, this is the ratio of the velocity of light in vacuum (c) to the velocity of light in a refractive material (for example, glass, plasma, etc.). (09 Oct 1997) |
| law of refraction | For two given media, the sine of the angle of incidence bears a constant relation to the sine of the angle of refraction. Synonym: Descartes' law, Snell's law. (05 Mar 2000) |
| affective personality disorder | A disturbance of feelings or mood expressed as a milder form of depression and related emotional features that colour the whole psychic life and for which psychosocial stressors are believed to play the major role. (05 Mar 2000) |
| alcohol amnestic disorder | <psychiatry> A mental disorder with brain damage characterised by amnesia, compensatory confabulation, disturbance of attention, and peripheral neuritis. It is usually associated with alcoholism and dietary deficiencies. (12 Dec 1998) |
| antisocial personality disorder | <psychiatry> An individual who engages in deviant behaviour with lack of remorse. (13 Jan 1998) |
| asthenic personality disorder | A personality type characterised by low energy level, easy fatigability, incapacity for enjoyment, lack of enthusiasm, and oversensitivity to physical and emotional stress. When appearing in marked form it becomes a psychological disorder (asthenic personality disorder), also called dependent personality. Synonym: asthenic personality disorder, dependent personality disorder. (05 Mar 2000) |
| attention deficit disorder | An inability to control behaviour due to difficulty in processing neural stimuli. (12 Dec 1998) |
| attention deficit disorder with hyperactivity | A behaviour disorder originating in childhood in which the essential features are signs of developmentally inappropriate inattention, impulsivity, and hyperactivity. Although most individuals have symptoms of both inattention and hyperactivity-impulsivity, one or the other pattern may be predominant. The disorder is more frequent in males than females. Onset is in childhood. Symptoms often attenuate during late adolescence although a minority experience the full complement of symptoms into mid-adulthood. (12 Dec 1998) |