Emergency vehicle lighting is one or more visual warning lights fitted to a vehicle for use when the driver wishes to convey to other road users the urgency of their journey, to provide additional warning of a hazard when stationary, or in the case of law enforcement as a means of signalling another driver to stop for interaction with an officer.
Grossular dodecahedron, .7 cm across, from Coahuila, Mexico. Grossular is a calcium-aluminium species of the garnet group of minerals. It has the chemical formula of Ca3Al2(SiO4)3 but the calcium may, in part, be replaced by ferrous iron and the aluminium by ferric iron.
Macular Degeneration. Definition. Macular degeneration is the progressive deterioration of a critical region of the retina called the macula. The macula is a 3-5 mm area in the retina that is responsible for central vision. This disorder leads to irreversible loss of central vision, although peripheral vision is retained.