| low sodium syndrome | <syndrome> A syndrome resulting from salt restriction and use of diuretics in treatment of congestive heart failure and hypertension, characterised by weakness, drowsiness, muscle cramps, and a reduction in glomerular filtration with consequent nitrogen retention, renal failure, and sometimes death; occurs also in cirrhosis of the liver with ascites and in adrenal insufficiency. Synonym: salt depletion syndrome. (05 Mar 2000) |
|---|---|
| low spinal anaesthesia | Spinal anaesthesia in which the level of sensory denervation extends to the tenth or eleventh thoracic dermatome. (05 Mar 2000) |
| low tension glaucoma | Optic nerve atrophy and excavation with typical field defects of glaucoma but without abnormal increase in intraocular pressure. (05 Mar 2000) |
| low tone deafness | Inability to hear low notes or frequencies. (05 Mar 2000) |
| low wine | The first weak distillate obtained from the mash in the process of making whisky. (05 Mar 2000) |
| lymphoma, low-grade | One of the three major prognostic groupings for non-hodgkin lymphomas as proposed in the working formulation of the non-hodgkin's lymphoma pathologic classification project sponsored by the national cancer institute (1981). Lymphomas falling within this group have a relatively favourable survival potential. (12 Dec 1998) |
| auditory field | The space included within the limits of hearing of a definite sound, as of a tuning fork. (05 Mar 2000) |
| bright field illumination | <microscopy> The method of lighting the specimen with a solid cone of rays. Transmitted bright field illumination is performed by a substage condenser. Reflected bright field illumination is performed by a vertical illuminator. Compare: dark field illumination (05 Aug 1998) |
| bright field imaging | <microscopy> An imaging mode in a transmission electron microscopy that uses only unscattered Electrons to form the image. Contrast in such an image is due entirely to mass-thickness variations in amorphous samples, and may include diffraction contrast in crystalline samples. (05 Aug 1998) |
| bright field microscopy | <technique> Optical microscopy, in which absorption to a great extent and diffraction to a minor extent give rise to the image, as opposed to phase contrast or interference methods of microscopy. (18 Nov 1997) |
| Broca's field | The posterior part of the inferior frontal gyrus of the left or dominant hemisphere, corresponding approximately to Brodmann's area 44; Broca identified this region as an essential component of the motor mechanisms governing articulated speech. Synonym: Broca's area, Broca's field, motor speech centre. (05 Mar 2000) |
| cardioid dark field condenser | <microscopy> A condenser designed with two reflecting surfaces, the first, a spherical surface which reflects the rays to a second, cardioid (heart-shaped) surface. The virtue in such an arrangement is that, if the cardioid surface is of true figure, the lens is both achromatic and aplanatic. It has a limiting numerical aperture of about 1.0. Thus objectives of a greater numerical aperture cannot be used successfully with it. A true cardioid figure is the trace of a point on the circumference of a circle rolling around an equal, fixed circle. (05 Aug 1998) |
| magnetic field | The sphere of influence of a magnet. (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) |
| paraboloid dark field condenser | <microscopy> A lens of parabolic shape. The vertex end is ground back so that its focus can be brought into coincidence with the specimen on the slide. A central stop is provided to block the central rays. It is used chiefly for medium- power work. (05 Aug 1998) |