Background In westernized societies, acne vulgaris is a nearly universal skin disease afflicting 79% to 95% of the adolescent population. In men and women older than 25 years, 40% to 54% have some degree of facial acne, and clinical facial acne persists into middle age in 12% of women and 3% of men. Epidemiological evidence suggests that acne incidence rates are considerably lower in nonwesternized societies. Herein we report the prevalence of acne in 2 nonwesternized populations: the Kitavan Islanders of Papua New Guinea and the Aché hunter-gatherers of Paraguay. Additionally, we analyze how elements in nonwesternized environments may influence the development of acne.
WSN nodes resource constrained. In order to keep the size and the cost of the nodes down, the nodes have limited processing power, memory and radio range. However, the resource constraint which has the most significant impact on many WSNs is the constraint on energy. WSN nodes are battery operated. Many wireless sensor networks are deployed in locations where battery replacement is not feasible. A node has to be discarded when the battery depletes. Energy scavenging may alleviate this problem in some sensor networks. Most WSN protocols are very conscious of the limited supply of energy, and try to conserve energy.
In medieval manuscript book s, the collated quire s were sewn onto leather or hemp cords , and the loose ends of the cord s were threaded into grooves cut in the inner surface of the wooden boards and secured with peg s or nails. The spine and outside surface of the boards were covered in damp leather or parchment and the grooves concealed by gluing a leaf, called the paste-down , to the inside of each cover. The cover might then be decorated, usually by blocking or tooling , and metal boss es and cornerpiece s added to protect the binding from wear, with one or more clasp s attached to the edge s to keep the volume tightly closed when not in use. During the early Middle Ages, binding was done in monastic scriptoria , but by the late Middle Ages, this stage of book production was done by the stationer or bookseller .