| TH, Th, | Th T-helper [lymphocyte]; thenar; therapist; therapy; thoracic, thorax; thorium; throat |
|---|---|
| thor | thorax, thoracic |
| LSO | lateral superior olive; left salpingo-oophorectomy; left superior oblique; lumbosacral orthosis |
| ASIS | Anterior Superior Iliac Spine |
| ECG | Electro-Cardio-Graphy(-Gram); 심전도 = EKG 1. Conducting System Structu... |
| aperture for electron microscopy | <technique> Anode aperture: The opening in the accelerating voltage anode shield of the electron gun through which the electrons must pass to irradiate the specimen. Condenser aperture: An opening in the condenser lens controlling the number of electrons entering the lens and the angular aperture of the electron beam. The angular aperture can also be controlled by the condenser lens current. Physical objective aperture: A metallic diaphragm, with a small central hole, used to limit the cone of electrons accepted by the objective lens. This improves image-contrast since highly scattered electrons are prevented from arriving at the Gaussian image plane and therefore cannot contribute to background fog. Aplanatic. Free from spherical aberration and coma. (05 Aug 1998) |
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| aperture function | <microscopy> In a diffraction-limited optical system, the function that determines the relationship between the image and each point in the object. Modifying the aperture function changes the image according to the modified Fourier-filtering (or optical filtration) property of the aperture. (05 Aug 1998) |
| aperture of mastoid antrum | The orifice leading from the epitympanic recess to the mastoid antrum. Synonym: aditus ad antrum. (05 Mar 2000) |
| aperture of orbit | The somewhat quadrangular anterior entrance to the orbit which forms the base of the pyramid-shaped orbital cavity. It is bounded by the sharp supra-, infra-, and lateral orbital margins and a less obvious medial margin on each side of the upper nose. Synonym: aditus orbitae, aperture of orbit. (05 Mar 2000) |
| aperture plane | <microscopy> In a microscope adjusted for Koehler illumination, the conjugate planes that include the light source, the condenser iris diaphragm, the objective lens back aperture, and the eye point. Spaces in the aperture planes are the reciprocal of those in the field planes. (05 Aug 1998) |
| back aperture | <microscopy> The exit pupil of a microscope objective lens. The objective lens back aperture, which can be examined with a phase telescope or by inserting a Bertrand lens, displays the conoscopic interference figure and diffraction patterns. (05 Aug 1998) |
| relative aperture | <microscopy> The ratio of the focal length of a lens to the diameter of its entrance pupil. This gives a number known as the f-number, usually written f:8, f:16, etc. Thus, if the focal length is divided by the number 8, 16, etc., the result will be the diameter of the entrance pupil of the lens, or if the diaphragm of the lens is wide open it will be very nearly the diameter of the free aperture of the lens. See: F-number. (05 Aug 1998) |
| medial aperture of the fourth ventricle | The large midline opening in the posterior inferior part of the roof of the fourth ventricle, connecting the ventricle with the cerebellomedullary cistern. Synonym: apertura mediana ventriculi quarti, arachnoid foramen, Magendie's foramen, median aperture of the fourth ventricle. (05 Mar 2000) |
| median aperture of the fourth ventricle | The large midline opening in the posterior inferior part of the roof of the fourth ventricle, connecting the ventricle with the cerebellomedullary cistern. Synonym: apertura mediana ventriculi quarti, arachnoid foramen, Magendie's foramen, median aperture of the fourth ventricle. (05 Mar 2000) |
| contra-aperture | A second opening made at the dependent part of an abscess or other cavity containing fluid, which is not draining satisfactorily through an opening previously made. Synonym: contra-aperture, counterpuncture. (05 Mar 2000) |
| pyriform aperture wiring | A method of wiring using the nasal bones at the area of the pyriform aperture for the stabilization of fractures of the jaw. (05 Mar 2000) |
| sphenoidal sinus aperture | One of the pair of openings in the body of the sphenoid bone through which the sphenoid sinuses communicate with the sphenoethmoidal recess of the nasal cavity. Synonym: apertura sinus sphenoidalis, sphenoidal sinus aperture. (05 Mar 2000) |
| numerical aperture | For a lens the resolving power depends upon the wavelength of light being used and inversely upon the numerical aperture. The N.A. Is the product of the refractive index of the medium (1 for air, 1.5 for immersion oil) and the sine of the angle, i, the semi angle of the cone formed by joining objects to the perimeter of the lens. The larger the value of N.A., the better the resolving power of the lens, most objectives have their N.A. Value engraved on the barrel and this should be quoted when describing an optical system. (18 Nov 1997) |
| inferior pelvic aperture | The lower opening of the true pelvis, bounded anteriorly by the pubic arch, laterally by the rami of the ischium and the sacrotuberous ligament on either side, and posteriorly by these ligaments and the tip of the coccyx. Synonym: apertura pelvis inferior, apertura pelvis minoris, fourth parallel pelvic plane, pelvic outlet, pelvic plane of outlet, plane of outlet. (05 Mar 2000) |
| inferior thoracic aperture | The inferior boundary of the bony thorax composed of the twelfth thoracic vertebra and the lower margins of the rib cage and sternum. Synonym: apertura thoracis inferior. (05 Mar 2000) |