| zero energy thermonuclear assembly | <radiobiology> A British fusion device in which scientists observed fusion neutrons in 1958. They were erroneously considered to be thermonuclear (coming from particles with a Maxwellian velocity distribution) and were a cause for the initial optimism that fusion energy would be easy. They were actually due to electromagnetic acceleration during a plasma instability, an effect which cannot be scaled up to produce useful energy. (09 Oct 1997) |
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| zero gravity | A physical state existing in space or at a time in flight when the centrifugal thrust of a parabolic glide or turn exactly counteracts the force of gravity. (05 Mar 2000) |
| zero-order reaction | A reaction that proceeds at a particular rate independently of the concentration of the reactant or reactants. (05 Mar 2000) |
| zero time-binding DNA | DNA that has become the duplex form at the start of a reassociation process. Acronym: DNA (05 Mar 2000) |
| alveolar point | The most anterior point on the maxillary alveolar process in the midline. Synonym: alveolar point, prostheon. Origin: G. Ntr. Of prosthios, foremost (05 Mar 2000) |
| anterior focal point | The point where parallel rays from the retina are focused. (05 Mar 2000) |
| apophysial point | The centre of the root of the anterior nasal spine. Synonym: apophysary point, apophysial point, spinal point. (05 Mar 2000) |
| arrow point tracing | A tracing of mandibular movements made by means of a device attached to the opposing arches; its shape resembles that of an arrowhead or a Gothic arch, and when the instrument's marking point is at the apex of the arch, the jaws are considered to be in centric relation. Synonym: arrow point tracing, Gothic arch tracing, Gothic arch, stylus tracing. (05 Mar 2000) |
| auricular point | A craniometric point at the centre of the opening of the external acoustic meatus; or, in certain cases, the middle of the upper edge of this opening. Synonym: auricular point. Origin: L. Auricularis, pertaining to the ear (05 Mar 2000) |
| axial point | One of two point's in a compound optical system so related that a ray directed toward the first point will appear to have passed through the second point parallel to its original direction. Synonym: axial point. (05 Mar 2000) |
| boiling point | This is the temperature at which the vapor pressure of a given liquid reaches atmospheric pressure (and thus starts to boil). (09 Oct 1997) |
| boiling point elevation | This is the phenomenon of increasing the temperature at which a liquid boils by dissolving another substance in the liquid (for example: you can raise the temperature at which water boils by adding salt to it). (09 Oct 1997) |
| Cannon's point | The location in the mid-transverse colon at which innervation by superior and inferior mesenteric plexuses overlap at the junction of the primitive midgut and hindgut, frequently resulting in narrowing evident on barium enema. See: Cannon's ring. Synonym: Cannon's ring. (05 Mar 2000) |
| painful point | See: Valleix's points. (05 Mar 2000) |
| malar point | Apex of the tuberosity of the zygomatic (malar) bone. (05 Mar 2000) |