| mercury arc | An electric discharge through mercury vapor between electrodes, one of which is usually mercury; provides a rich source of therapeutic ultraviolet rays; the containing tube is usually quartz; may also be glass with a fluorite window. (05 Mar 2000) |
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| Riolan's arc | The series of arterial arches formed in the mesentery by anastomoses between adjacent jejunal and ileal arteries and from which vasa recta arise. The arterial arcades of the ileum are shorter and more complex than those of the jejunum. See: arterial arches of ileum, arterial arches of jejunum. Synonym: intermesenteric arterial anastomosis, Riolan's arc, Riolan's arcades. (05 Mar 2000) |
| crater arc | An arc of a direct current that forms a pitlike excavation at the positive pole. (05 Mar 2000) |
| pulmonary arc | An obsolete term for pulmonary salient. (05 Mar 2000) |
| nasobregmatic arc | A line running through the midline of the forehead from the nasion to the bregma. (05 Mar 2000) |
| naso-occipital arc | The arc in the midline from the root of the nose to the inferior limit of the external occipital protuberance. (05 Mar 2000) |
| interauricular arc | A line carried over the cranium from the centre of one external auditory meatus to that of the other. Synonym: interauricular arc. (05 Mar 2000) |
| tungsten arc lamp | <apparatus> A lamp having highly compressed tungsten elements. (05 Mar 2000) |
| unipolar arc | <radiobiology> Arc between a metal surface and a plasma in contact with it. Such an arc requires only one electrode and is maintained by the thermal energy of the electrons. (09 Oct 1997) |
| flame arc | An arc between two impregnated electrodes that causes volatilization of the core with resultant flame. (05 Mar 2000) |
| longitudinal arc of skull | The line carried over the skull in the midline from the nasion to the opisthion. (05 Mar 2000) |