| AES | acetone-extracted serum; American Electroencephalographic Society; American Encephalographic Society... |
|---|---|
| AOS | American Ophthalmological Society; American Otological Society; anodal opening sound; anterior [o]es... |
| AS | acetylstrophanthidin; acidified serum; acoustic schwannoma; acoustic stimulation; active sarcoidosis... |
| ES | ejection sound; elastic stocking; electrical stimulus, electrical stimulation; electroshock; emergen... |
| FHS | fetal heart sound; fetal hydantoin syndrome; Floating Harbor syndrome |
| Jewett sound | A short straight sound for dilating the anterior urethra. (05 Mar 2000) |
|---|---|
| first heart sound | Occurs with ventricular systole and is mainly produced by closure of the atrioventricular valves. (05 Mar 2000) |
| fourth heart sound | The sound produced in late diastole in association with ventricular filling due to atrial systole and related to reduced ventricular compliance. It is a low frequency oscillation that may be normal at older ages owing to a physiologic decline in ventricular compliance but is nearly always abnormal at younger ages if it is of high intensity or palpable. It is common in ventricular hypertrophy, particularly with hypertension, and is almost invariable during acute myocardial infarction. Fourth heart sounds may arise from the right or left ventricle or both. Synonym: atrial sound. (05 Mar 2000) |
| friction sound | The sound, heard on auscultation, made by the rubbing of two opposed serous surfaces roughened by an inflammatory exudate, or, if chronic, by nonadhesive fibrosis. Synonym: friction murmur, friction rub. (05 Mar 2000) |
| Le Fort sound | A curved sound threaded for a filiform bougie, used for dilation of urethral strictures in the male when small caliber or presence of false passages prevents safe passage of a standard sound or catheter. (05 Mar 2000) |
| 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) |
| receptive field | That part of the retina whose photoreceptors (rods and cones) pertain to a single optic nerve fibre. The response of a neuron to stimulation of its receptive field depends on the type of neuron and the part of the field that is illuminated; an "on-centre" neuron is stimulated by light falling at the centre of its receptive field and inhibited by light falling at the periphery; an "off-centre" neuron reacts in exactly the opposite fashion; that is, it is inhibited by light falling at the centre of its receptive field. In either case, the net response depends on a complex switching action in the retina. When an entire receptive field is equally illuminated, the response of receptors at the centre of the field predominates. (05 Mar 2000) |