| Mach line | The apparent line of contrasting density bordering a soft tissue shadow on a radiograph; it is an optical illusion constructed by the observer's retina. (05 Mar 2000) |
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| Mach effect | The appearance of a light or dark line on a radiograph where there is a concave or convex interface in the subject, a physiological optical form of edge enhancement. See: Mach's band. (05 Mar 2000) |
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| Mach, Ernst | <person> Austrian scientist, 1838-1916. See: Mach's band, Mach number. (05 Mar 2000) |
| Mach number | A number representing the ratio between the speed of an object moving through a fluid medium, such as air, and the speed of sound in the same medium. (05 Mar 2000) |
| Mach's band | A relatively bright or dark band perceived in a zone where the luminance increases or decreases rapidly. (05 Mar 2000) |
| Mach Zehnder system | Interferometric system in which the original light beam is divided by a semi transparent mirror: object and reference beams pass through separate optical systems and are recombined by a second semi transparent mirror. Interference fringes are displaced if the optical path difference for the reference beam is greater and this can be compensated with a wedge shaped auxiliary object. The position of the wedge allows the phase retardation of the object to be measured. The Mach Zehnder system was used in a microscope designed by Leitz. (18 Nov 1997) |
| mach-zender interferometer | <radiobiology> This is a variation of the Michelson interferometer which is used mainly in measuring the spatial variation in the refractive index of a gas (or plasma). A Mach-Zender interferometer uses two semi-transparent mirrors and two fully reflective mirrors located at the corners of a rectangle. The incoming beam is split in two at the first semi-transparent mirror, and the two halves of the beam travel along separate paths around the edge of the rectangle, meeting at the opposite corner. Typically one beam is a control, and the other travels through the system under study. The two beams meet at the second semi-transparent mirror, after which they are mixed together and interfere. (09 Oct 1997) |
| magnetic mach number | <physics> A dimensionless number equal to the ratio of the velocity of a fluid to the velocity of Alfven waves in that fluid. (13 Nov 1997) |
| alveolonasal line | A line connecting the alveolar point and the nasion. (05 Mar 2000) |
| Amberg's lateral sinus line | A line dividing the angle formed by the anterior edge of the mastoid process and the temporal line. (05 Mar 2000) |
| anocutaneous line | The line between the simple columnar epithelium of the rectum and the stratified epithelium of the anal canal. Synonym: linea anocutanea, anocutaneous line, dentate line. (05 Mar 2000) |
| anterior axillary line | A vertical line extending inferiorly from the anterior axillary fold. Synonym: linea axillaris anterior, linea preaxillaris, preaxillary line. (05 Mar 2000) |
| anterior junction line | Radiographic projection of the mediastinal tissue septum between the upper lobes behind the sternum. (05 Mar 2000) |
| anterior median line | The line of intersection of the midsagittal plane with the anterior surface of the body. Synonym: linea mediana anterior. (05 Mar 2000) |
| arcuate line | An arching or bow-shaped line. See: arcuate line of ilium, arcuate line of rectus sheath. Synonym: linea arcuata. (05 Mar 2000) |
| arcuate line of ilium | The iliac portion of the linea terminalis of the bony pelvis. Synonym: linea arcuata ossis ilii. (05 Mar 2000) |