null surface
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Null surface — In the theory of relativity, a null surface is a 3 surface whose normal vector is everywhere null (zero length with respect to the local Lorentz metric), but the vector is not identically zero. For example, light cones are null surfaces.… … Wikipedia
Trapped null surface — A trapped null surface is a set of points defined in the context of general relativity as a closed surface on which outward pointing light rays are actually converging (moving inwards).Trapped null surfaces are used in the definition of the… … Wikipedia
Null-O — is a 1958 science fiction short story by Philip K. Dick. This rather brief story examines the concept of totally unempathic and logical humans ( Null O s) in an obvious parody of the plot and concepts of The Players of Null A by A. E. van Vogt.… … Wikipedia
null cell — nəl n a lymphocyte in the blood that does not have on its surface the receptors typical of either mature B cells or T cells … Medical dictionary
Null corrector — Testing a spherical mirror using an interferometer. All surfaces in the tester are either flat or spherical, so the tester itself is fairly easy to fabricate and test. This setup can test a spherical mirror of any size since the wavefront is… … Wikipedia
Null allomorph — In morpheme based morphology, a null allomorph or zero allomorph is a special kind of allomorph which has the form of a null morpheme. Because there are contexts in which the underlying morpheme still appears in the surface structure, a real null … Wikipedia
Surface normal — Normal vector redirects here. For a normalized vector, or vector of length one, see unit vector. A polygon and two of its normal vectors … Wikipedia
Null cell — A null cell is a large granular lymphocyte without surface markers or membrane associated proteins from B lymphocytes or T lymphocytes. Natural killer cells are usually null cells with surface marker CD 16 which bind to the Fc portion of the IgG … Wikipedia
Surface gravity — The surface gravity, g , of an astronomical or other object is the gravitational acceleration experienced at its surface. The surface gravity may be thought of as the acceleration due to gravity experienced by a hypothetical test particle which… … Wikipedia
Surface Enhanced Raman Scattering — Illustration von Rayleigh , Strokes und Anti Strokes Streuung Als Raman Streuung (auch Raman Effekt oder Smekal Raman Effekt) wird die inelastische Streuung von Licht an Atomen oder Molekülen bezeichnet. Sie ist nach Chandrasekhara Raman benannt … Deutsch Wikipedia
null cells — lymphocytes that lack the surface markers for B or T cells; see K c s and NK c s … Medical dictionary
