Subtropics

Malaria affects an estimated 270 million people and causes 2—3 million deaths annually, approximately one million of which occur in children under the age of five. While primarily an affliction of the tropics and subtropics, it has occurred as far north as the Arctic Circle. The disease essentially has been eradicated in most temperate-zone countries, but some 1100 cases of malaria in U.S. citizens returning from abroad were reported to the Centers for Disease Control during 1990. Malaria is seen today in Southeast Asia, Africa, and Central and South America. It is on the increase in Afghanistan, Brazil, China, India, Mexico, the Philippines, Sri Lanka, Thailand, and Vietnam. Escalation of the disease is because of the discontinued use of the insecticide DDT which effectively kills mosquito larvae, but has been found to be toxic to Hvestock and wildlife. Also, chloroquine (6), a reUable dmg for the prophylaxis and treatment of falcipamm malaria, is ineffective in many parts of the world because of the spread of dmg-resistant strains. 

Whereas commercial production of castor oil existed ia the United States ia the 1800s, production shifted to tropical and subtropical countries ia the early 1900s. World War I, World War II, and the Korean conflict each iafluenced efforts to produce hybrid castor species and iacrease U.S. planting, and by the late 1960s, approximately 80,000 acres of castor were grown ia the United States produciag 29,500 metric tons of castor oil. U.S. production was competitive until 1972 when Federal price supports were withdrawn. U.S. production dropped almost to zero by 1974. 

High alumina minerals are found where intense weathering and leaching has dissolved the siHca. It is generally befleved that a very humid, subtropical climate is required for this (lateritic) stage of weathering. 

The number of clear human epidemiologic studies is small. A total of approximately 50 compounds (c.g., benzene, vinyl chloride) and complex e.xposures (e.g., aluminum production, tobacco smoke) have sufficient data available to permit their classification as human carcinogens. The most potent human carcinogens known, the aflatoxins. are of natural origin. Their presence in food products through infestation by toxin-producing fungi constitute a serious problem in several tropical and subtropical countries. 

Air conditioning has been another revolutionary application of electricity. The technique was first patented by William Carrier in 1902 but widespread adoption came only after I960, opciiing up first the American Sunbelt to mass migration from northern states, then increasing the appeal of subtropical and... 

Ocean thermal energy conversion (OTEC) power plants generate electricity by exploiting the difference in temperature between warm water at the ocean surface and colder waters found at ocean depths. To effectively capture this solar energy, a temperature difference of 35°F or more between surface waters and water at depths of up to 3,000 feet is required. This situation can be found in most of the tropical and subtropical oceans around the world that are in latitudes between 20 degrees north and 20 degrees south. 

Three fungal infections - Madura feet (mycetoma), chromomycosis and sporotrichosis - fall into the category of subcutaneous mycoses, their distribution is mainly in tropical and subtropical areas. The ideal treatment for madura feet caused by fungi is not yet established the azoles are of some benefit, however, neither the optimal drug, dose, nor the treatment schedules are known. Chromomycosis responds well to ITRA monotherapy or the combination of 5FC plus ITRA. ITRA has been set up as standard therapy for cutaneous and lymphatic sporotrichosis. 

Entamoeba histolytica is an anaerobic rhizopod that occurs in tropical and subtropical areas. It can cause intestinal and extraintestinal manifestations. It is transmitted orally by ingestion of cysts that develop into trophozoites in the large intestine. Amebic trophozoites release several cytolytic factors, e.g. amoe-bapore, which enable the parasite to invade tissue. In intestinal amoebiasis, E. histolyticatrophozoites invade the intestinal mucosa, causing a form of ulcerative colitis with bloody and mucous diarrhoea. Extraintestinal manifestation of amebiasis results in abscess formation, usually in the liver but sometimes in the brain. 

Leprosy, also referred to as Hansen s disease, is caused by the bacterium Mycobacterium leprae. Although rare in colder climates, this disease may be seen in tropical and subtropical zones. Dapsone and clofazimine (Lamprene) are the two drags currently used to treat leprosy. The leprostatic drugs are listed in the Summaiy Drug Table Leprostatic Dragp. 

Transitional waters between subtropical and subpolar zones extremity of the areas of equatorial divergences 140 336 4.22 10.1 LOW (13- ) 1.3- 1 S S... 

Figure 7-7 depicts the transport of one substance - water - due to the general circulation. Here we see the overall consequence of the general circulation with its systematic pattern of vertical motions and weather systems. Water evaporates from the oceans and land surfaces at subtropical latitudes and is transported both toward the equator and the poles. Precipitation falls largely at the equator and in the mid-latitudes. Hence, the subtropics are arid, with evaporation exceeding precipitation. The polar regions likewise are arid due to water having been removed in mid-latitude weather systems prior to arrival in the Arctic... 

Vertisols > 30% shrink-swell clays, cracking in dry season, deep A Temperate to subtropical grasslands... 

Earth (Li, 1976). The high denudation rate is a reflection of the poorly lithifled, highly tecton-ized nature of the sedimentary rocks that compose the island. Sediment-yield data compiled by Milliman and Meade (1983) and Milliman and Syvitski (1992) indicate that island arcs and mountain belts in the tropical and subtropical west Pacific may contribute as more than 22% of all solid material discharged by rivers into the ocean. Furthermore, the tropical mountainous areas in southeast Asia and India may contribute another 33%. 

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