The point at which pain becomes INTOLERABLE is known as the pain perception threshold. Studies have found this point to be similar among different social and cultural groups. However, the pain tolerance threshold varies significantly among these groups. A stoical, unemotional response to pain may be seen as a sign of braveness in certain cultural or social environments. However, this behavior can also mask the seriousness of an injury to an examining physician.
Nutrition additives are utilized to restore nutrients lost during production, to ENRICH certain foods in order to correct dietary deficiencies or to add nutrients to food substitutes. Nowadays, vitamins are commonly added to many foods in order to increase their nutritional value. For example, vitamins A and D are added to dairy and cereal products, and several of the B vitamins are added to cereals.
In modern manufacturing production facilities that produce equipment sensitive to environmental contamination, a dust-free working area with strict temperature and humidity controls is of VITAL importance. Seamless plastic walls and ceilings, external lighting, a continuous flow of dust-free air, and daily cleaning are features of this "clean room." Workers wear special clothing, including head coverings. When entering this room, they pass through a "shower" to remove contaminants.
Human populations are classified in terms of genetically transmitted traits. For groups that have lived for generations in certain locations, research illustrates the long-term genetic effects of environmental factos such as climate and diet. ONGOING investigations track the history of evolution and its genetic changes and help to explain the origin of genetically determined disesase and their long-term influence.
In the 1890s, a rising generation of young antiorganization leaders came on the political scene. These leaders transformed the art and practice of politics in the United States, by exercising strong leadership and by bringing about institutional changes that helped REVIATALIZE polictical democracy. Most important was their achievement of economic and social objectives, such as legislation to prevent child labor, and accident insurance systems to provide compensation to injured workers.
There are more than 100 types of species of chameleon. A member of the lizard family, the chameleon lives in countries as diverse as Madagascar, Spain, and Sri Lanka. It is thought to change color to CONFORM TO its surroundings, but that is rarely true. While changes do occur with changes in light or remperature, especially when the chameleon is frightened, its new color rarely matches its immediate surroundings.