Biack body

Emissivity - The ratio of the radiant energy (heat) ieaving (being emitted by) a surface to that of a biack body at the same temperature and with the same area expressed as a number between 0 and 1. 

The opening to a cavity inside a hoiiow object is a good approximation of a biack body The hoie acts as a perfect absorber. 

Nutrient chemistry of coastai upweiiing regions supporting anoxic water coiumns and infiuenced by N2 production (biack diamonds), compared to the nutrient chemistry of adjacent water bodies unaffected by water-coiumn anoxic conditions (open circies). Source-. From Canfieid, D. E. (2006). Geochimica et Cosmochimica Acta 70, 5753-5765. 

Potassium is found in the fiuids of the body as the K+ ion, and its presence is essentiai to the operation of our nervous system. The passage of impuises aiong the nerves requires the fiow of (and Na+) through channeis in the membranes of the nerve ceiis. Faiiure of this ion fiow prevents nerve transmissions and resuits in death. For exampie, the biack mamba snake kiiis its victims by injecting a venom that biocks the potassium channeis in the nerve ceiis. 

Schwarzschild radius A critical radius of a body of given mass that must be exceeded if light is to escape from that body. It equals 2GM/( , where G is the gravitational constant, c is the speed of iight, and Mis the mass of the body. If the body collapses to such an extent that its radius is less than the Schwarzschild radius the escape velocity becomes equal to the speed of light and the object becomes a biack hoie. The Schwarz-schiid radius is then the radius of the hole s event horizon, it is named after Karl Schwarzschild (1873-1916). 

Figure 2.2 Schematics of 3DLAI fabrics with body warp weavers (red), surface warp weavers (gray), warp stuffers (biack), and fiiiing tows (biue).

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