Most babies are able to begin sitting up when they reach the age of 4 months. However, some of them might need more time and start sitting independently when they become 7 months old. Until this time, the baby would definitely have learned how to roll and would be able to hold his head up too.
UV radiation, in the form of lasers, lamps, or a combination of these devices and topical medications that increase UV sensitivity, are sometimes used to treat patients with certain diseases who have not responded to other methods of therapy.
UV Light. UV light is measured in microwatts of ultraviolet radiation per lumen of visible light (ÂµW/l). The high energy of UV radiation is particularly damaging to artifacts. UV light is not visible to the human eye and therefore removing it from museum lighting causes no change in appearance. Daylight is generally the strongest source of UV light; fluorescent, metal halide and mercury vapor lights also emit UV radiation.