The use of the black dye can be limited to a small number of cells or to more extensive groups; occasionally one may even obtain a comprehensive view of an entire area of the central nervous system.
An effective pre-drainage system in a limitedarea that has a high water head and huge inflow is important to prevent flooding accidents during subsea tunnelling.
DWDM technology has been widely used in long-distance communications, but its high system cost has greatly limited its application into metro area networks (MAN).