In 2006, 39.5 million people were currently infected with HIV, and there were 4.3 million new infections, making HIV one of the greatest health crises in human history. There is a desperate need to develop new methods to prevent HIV infection. The results of three large randomised trials of male circumcision, carried out in South Africa [1], Kenya [2] and Uganda [3], leave no doubt that circumcision more than halves a man’s risk of HIV infection [4,5], and the protective effect is thought to be due to the physical removal of most of the inner foreskin epithelium. This epithelium is richly supplied with Langerhans cells, the main site of HIV entry into the penis [6]. However, Langerhans cells are also a vital part of the body's natural epithelial defence against HIV infection, since they contain the c-type lectin Langerin that normally degrades any virions entering the cell [7,8]. When large amounts of virus are present, the Langerin reserves may be depleted, so that the Langerhans cells instead become vectors for transporting virus to the regional lymph nodes, establishing a systemic infection.
Langerhans cells are also the primary site of HIV entry into the female reproductive tract [9]. It has long been known that the human vaginal epithelium responds to topical oestrogen administration by thickening and keratinization, and vaginal oestrogen cream or tablets are widely used by postmenopausal women to treat vaginal atrophy [10,11]. The vaginal epithelial structure has a direct effect on its susceptibility to HIV infection. A decline in oestrogen levels in women after the menopause is associated with a four to eightfold increased risk of contracting HIV [12].
The general enjoyed his breakfast while reading his morning paper and listening to the international news channel. Hearing the Balkans mentioned—his area of responsibility he looked up as a foreign correspondent began to comment on the aftermath of an Allied bombing mission from the day before. The gruesome details suddenly made the general’s scrambled eggs a bit less appealing. The graphic pictures showed what appeared to be the remnants of an orphanage. There in the rubble lay a bloodstained, tattered doll. Those images left him wondering about the carnage that lay beneath the collapsed brick and mortar.
Had his staff miscalculated and inadvertently struck an orphanage? A similar misstep had occurred a few weeks ago when another bombing mission resulted in civilian casualties in a marketplace. As the general bemoaned the potential ramifications of accidentally bombing an orphanage, a memory surfaced. Years of flying high-performance aircraft had sharpened his senses, and something about the scene seemed familiar. Could that be the same bloodstained doll he had seen in photographs of the earlier marketplace mishap? The general had been briefed on the enemy’s rather low-tech yet successful use of deception. Was he, along with the rest of the world, a target of military deception? As he pondered this, his pager went off.
When a customer region has a demand for a quantity of an oil product, it is in general possible to meet the demand using a number of equivalent products. Many factors influence the proportions of component products that are combined to make an optimal supply chain decision. The factors include the season of the year, the locations of available equivalent products, and the availability of suitable and timely transportation.
A competitive supply chain plan depends on knowledge of the above factors, on business policy knowledge, and on inventory facts in SQL databases. Both the knowledge and the facts can change rapidly. This makes it difficult to write conventional application programs and SQL queries that can produce supply chain plans to meet demand profitably.
