West Nile virus is a member of the family of viruses that is called Flaviviridae. The virus is similar to other members of this viral family, is passed to humans from birds by the bite of a mosquito, and is capable of causing disease in humans. For example, another mosquito borne flavivirus causes St. Louis encephalitis in humans. West Nile virus is endemic in Africa. Periodic outbreaks have occur…
Orthopraxy or orthopraxis (from Greek orthos, "correct," and praxis, "action") denotes proper action, particularly in a religious context. It is contrasted with orthodoxy (orthos and doxa, "opinion"), which denotes proper belief. The word orthopraxy is of relatively recent invention and has been used above all in connection with Latin American "libe…
As applied to non-Western societies, the term Westernization is almost always equated with modernization. It is important, however, to distinguish between the two, for modernization, considered as an overhauling of African societies, predates the incursion of the West on the continent. Before the Europeans, the most important agents of modernization in Africa were the Arabs, who, after their settl…
The notion of Westernization in the Middle East raises a number of interrelated issues. First, it refers to a period (nineteenth to twentieth centuries) in which Middle Eastern intellectuals engaged Western political philosophy in a self-conscious search for modernity. Albert Hourani, in his groundbreaking Arabic Thought in the Liberal Age, 1798–1939 (1983), dates this engagement from Napol…
Westernization in world history can refer to the transmission and reception of European ideas, technology, lifestyles, and institutions throughout the globe. Much of the scholarly attention has tended to concentrate on the intensity and nature of that transmission during the era of European colonialism and its attempts to transform the very consciousness of the peoples it encountered. Although the…
Wetlands are low-lying, depressional ecosystems that are permanently or periodically saturated with water at or close to the surface. The vegetation of wetlands must be adapted to the physical and chemical stresses associated with flooded substrates. The most common types of wetlands are swamps, marshes, shallow open waters, and mires, the latter consisting of peat-accumulating fens and bogs. Wetl…
Wheat is one of the oldest and most important cereal crops. Wheat is grown for its grain, which is ground into flour used to make breads and pastas. Wheat consists of approximately 20 species in the genus Triticum of the grass family (Poaceae). The most important wheats are: Triticum aestivum, used to make bread; T. durum, used to make pasta; and T. compactum, used to make softer cakes, crackers, …
The whisk fern (Psilotum spp., family Psilotaceae) splays its leafless, whisk-like branches upward, and is a living fossil from the time before the dinosaurs. It can grow as an epiphyte in moist climates or as a terrestrial plant in drier areas. Found in the tropics from around the world, the whisk fern is descended from the first vascular land plants, the Rhyniophytes, which appeared about 400 mi…
During the first quarter of this century astronomers found that the brightest star in the sky, Sirius, was orbited by a much fainter companion. Analysis of the orbit yielded a mass for the companion similar to that of the sun while an analysis of its light suggested that its size was approximately the same as Earth's. Further observation revealed that these small massive stars are reasonabl…
White-eyes are 85 species of small, perching song-birds that constitute the family Zosteropidae. White-eyes occur in sub-Saharan Africa, South Asia, Japan, Southeast Asia, New Guinea, Australia, New Zealand, and many other islands in the Pacific and Indian Oceans. White-eyes are arboreal birds, occurring in a wide range of forest types, including mangroves, lowland forests, and montane forests. Th…
Whooping cough is a highly contagious disease caused by the bacteria Bordatella pertussis. It is characterized by classic paroxysms (spasms) of uncontrollable coughing, followed by a sharp intake of air which creates the characteristic "whoop" of the disease name. B. pertussis is uniquely a human pathogen, meaning that it neither causes disease in other animals, nor survives in human…
In genetics, the specific types of genes (alleles) carried by individuals in any population comprise that individual's genotype. The actual expression of those genes produces a set of observable characteristics (phenotype). In any population of organisms, the wild type (also often printed in a hyphenated form as "wild-type") represents the most common genotype. With many organ…
Prehistory makes clear that our ancestors continuously conceptualized their relations with the myriad forms of plants and animals with whom their existence was interwoven. These ancient musings, more mythological than scientific, were the first sustained efforts to comprehend the order of nature. The noun wildlife has been in use no more than 125 years. But the swirl of ideas around wildlife, howe…
It was once customary to consider all undomesticated species of vertebrate animals as wildlife. Birds and mammals still receive the greatest public interest and concern, consistently higher than those expressed for reptiles and amphibians. Most concern over fishes results from interest in sport and commercial value. The tendency in recent years has been to include more life-forms under the categor…
Many endangered species, or their body parts, are extremely valuable for one reason or another. In some cases, they are avidly sought by public zoos or botanical gardens, or by private collectors, who may be willing to pay large sums of money for living or dead specimens to add to their collection. In other cases, parts of an animal or plant may be valuable. This can result in species being killed…
The term wind refers to any flow of air relative to the Earth's surface in a roughly horizontal direction. Breezes that blow back and forth from a body of water to adjacent land areas—on-shore and off-shore breezes—are examples of wind. The ultimate cause of Earth's winds is solar energy. When sunlight strikes Earth's surface, it heats that surface differently. N…
Wind chill is the temperature felt by humans as a result of air blowing over exposed skin. The temperature Table 1. Illustration by Hans & Cassidy. Courtesy of Gale Group. that humans actually feel, called the sensible temperature, can be quite different from the temperature measured in the same location with a thermometer. The reason for such differences is that the human body cons…
Wind shear is the difference in speed or direction between two layers of air in the atmosphere. Wind shear may occur in either a vertical or horizontal orientation. An example of the former situation is the case in which one layer of air in the atmosphere is traveling from the west at a speed of 31 mph (50 kph) while a second layer above it is traveling in the same direction at a speed of 6.2 mph …
Wintergreen is the common name for an evergreen shrub belonging to the genus Gaultheria and heath family Ericaceae. Gaultheria procumbens is native to eastern North America and grows wild in sandy, wooded areas or shady clearings. This shrub grows 4-6 in (10-15 cm) high with creeping stems. Stalks grow from the stems and have elliptical, shiny green leaves and leathery leaves. During mid-summer, w…
Wisdom is irretrievably linked with age and experience in human societies. If wisdom comes mainly through age and experience, it also requires "sense" to achieve. It is associated with the capacity to deal with experience in a constructive manner. If someone acts in a way that seems sensible, we may use the phrase "he has sense." Sense is the internal quality that promo…
The word witchcraft is used in many different ways. The word witch is derived from Old English wicca (masc., "wizard") and wicce (fem., "witch"). The term wiccan ("witchcraft") referred to human acts intended to influence nature, usually through the use of power unavailable to all human beings. This use of the word witchcraft is synonymous with the more ge…
In contemporary scholarly and popular discourse, the term witchcraft refers to a wide variety of ideas, practices, and institutions. Among most social science scholars of Africa, particularly anthropologists, witchcraft is defined as an act of magic that results in harming a person or aspects of the material world on which he or she depends. In this context, witchcraft and magic are used interchan…
The wolverine (Gulo gulo) is an uncommonly large member of the weasel family (Mustelidae) that occurs in the subarctic and boreal forests of North America and northern Eurasia. The wolverine is famous for its aggressive, combative nature and its remarkable strength. Although the wolverine is only a medium-sized animal, it can dominate much larger animals during an aggressive encounter at a food so…
The term womanist first appeared in Alice Walker's In Search of Our Mothers' Gardens: Womanist Prose (1983), in which the author attributed the word's origin to Although Walker states that a womanist is a black feminist or feminist of color, she insists that a black feminist as womanist talks back to feminism, brings new demands and different perspectives to feminism, and comp…
Wombats are thickset, bear-like, Australian marsupials (order Marsupalial). They dig burrows, are about the size of a small dog, and have perpetually growing teeth (like placental rodents). Wombats are members of the family Vombatidae, which includes three species. The critically endangered Queensland or northern hairy-nosed wombat (Lasiorhinus krefftii) is limited to a small area of Queensland Na…
Before the women's movement and deconstruction, the term femininity was understood as the opposite of the more obvious masculinity. Femininity represented those traits, characteristics, behaviors, or thought patterns not associated with a given society's expectations of men. Until the cultural upheaval of the late 1960s in the United States and elsewhere, the sweetly patient "…
Since 1970 the history of African women has developed into a vital and steadily expanding area of research and study, motivated, as with other areas of women's history, by the development of the international feminist movement. African women's history also paralleled the expansion of African history following World War II, as scholars inside and outside of Africa began to focus on hi…
The prominent roles occupied by women in the legends and myths of that complex and diverse part of the world called Asia suggest that "histories" of women in Asia have existed for a very long time. That these legends have been shaped, written, and sometimes performed by men operating in androcentric cultural contexts does not negate the impression of power and consequence their narra…
In its short history (from the late 1960s in the United States) women's studies has moved around the world as an idea, a concept, a practice, and finally a field or Fach (German for specialty or field). As late as 1982 in Germany Frauenstudium was not considered a Fach and therefore could not be studied in the university but only in special or summer courses. By the early twentieth century …
Wood, also known as secondary xylem, is a composite of tissues found in trees. Secondary xylem is composed primarily of cells, called vessel elements in angiosperms, or of slightly different cells in gymnosperms called tracheids. These cells of secondary xylem, along with specialized cells of a type called parenchyma, are made by a meristematic tissue called the vascular cambium. As the vascular c…
The woolly mammoth (Mammuthus primigenius) was a large mammal that coexisted with early humans. It became extinct at the end of the last ice age, about 10,000 years ago. One of four species of mammoths, woolly mammoths were abundant on the cold tundra that extended beyond the glaciated ice fields of Europe, Asia, and North America. It is unclear whether the extinction of the woolly mammoth was a r…
Work as a unitary experience, set off in time and place from the rest of life, is a concept bound in the culture of wage labor (see especially Thompson, 1967, on disciplined promptness and time regulation accompanying factory work). Only when effort—physical and mental—is turned into a commodity sold to an employer who then monitors and controls it can we discern an abstract concept …
Who is doing more work: a weight lifter holding up, but not moving, a 200 lb (91 kg) barbell, or an office worker lifting a pen? The weight lifter is certainly exerting more effort, and many people would say he is doing more work. To a physicist, however, the office worker is doing more work as long as the weight lifter does not actually move the barbell. The weight lifter does a considerable amou…
The term world systems analysis was coined in 1974 by Immanuel Wallerstein to refer to a broad set of ideas about the global political economy, and especially the relationship between Latin America and the dominant economies of Europe and the United States, which were then gaining currency. The phrase world system is explored in detail in Wallerstein's famous book The Modern World-System: C…
The wren-warblers or Australian warblers are 83 species of birds that constitute the family Maluridae. These are nonmigratory birds, occurring in New Guinea, Australia, New Zealand, and nearby islands. Their usual habitat is forests, shrublands, and heaths. Wren-warblers are small birds, with a body length of 3.9-7.9 in (10 to 20 cm), including the long, cocked tail that many species have. Their w…
Wrens are 63 species of small, restless perching birds in the family Troglodytidae. Species of wrens are most diverse in North America and South America, although one species, the winter wren, breeds widely in Europe, Asia, and North Africa. Wrens occur in a wide range of habitats, including semidesert, prairie, savanna, forests, and wetlands. Species of wrens breed from the boreal zone to the hum…
Wrynecks are two species of small, woodpecker-like birds. Wrynecks are in the family Picidae, which also includes the woodpeckers and piculets. However, the distinctively different wrynecks are in their own sub-family, the Junginae. Wrynecks received their common name from their habit of twisting their head and neck when disturbed. The plumage of wrynecks is a mottled and cryptic brown, grey, and …
X-ray crystallography is a laboratory technique used for the study of the internal structure of crystalline materials. More specifically known as x-ray diffraction, the technique is based on the interference pattern produced as x rays pass through the three-dimensional, repeating pattern of atoms within a crystal lattice. The characteristic interference patterns produced are reflective of the mole…
When used by botanists and plant breeders, xenogamy (also called outbreeding) generally refers to a form of cross-pollination. Xenogamy is also a term more broadly used in genetics to describe the union of genetically unrelated organisms within the same species. In all cases, xenogamy promotes genetic diversity and thus, also enhances the overall fitness of a species. In some circumstances, xenoga…
As the end of the 1990s approached, the world became preoccupied with the coming of the Year 2000, nicknamed "Y2K" (Y for year and 2 times K, a standard designation for a thousand). Some were superstitious about the turning of year numbers to 2000, but many focused on a predicted technological problem commonly known as the"Y2K Glitch" or the "millennium bug…
The yaks are members of the family Bovidae (oxen), order Artiodactyla, which also includes the domestic cattle and existing wild cattle species such as the aurochs, the gaur or seladang, and the koupray. The generally accepted species name for yak is Bos grunniens, and it seems to have an affinity to bison, which belong to the same genus Bos. Like some other Bos species the yak is a large, massive…
Yams are any of the 10 economically important species of Dioscorea, a genus in the monocotyledonous family Dioscoriaceae. These species, all tropical in their origin, are cultivated for their edible tubers (enlarged, fleshy, usually underground storage stems). In the United States, the name yam is often misapplied to the sweet potato (Ipomea batatas). Yams are herbaceous plants whose stems twine u…
Yellow fever is a severe illness that causes outbreaks of epidemic proportions throughout Africa and tropical America. The first written evidence of such an epidemic dates back to a 1648 outbreak in the Yucatan Peninsula in Mexico. Since that time, much has been learned about the interesting transmission patterns of this devastating illness. A very safe, highly effective yellow fever vaccine exist…
In Chinese cosmology, yin and yang are two opposite but complementary principles that regulate the functioning of the cosmos. Their repeated alternation provides the energy necessary for the cosmos to sustain itself, and their continuous joining and separation is at the origin of the rise and the disappearance of the entities and phenomena that exist within the world of the "ten thousand th…
The word yoga comes from a Sanskrit verbal root meaning "to yoke, harness" and in general refers to one or another of the many psycho-physical techniques in Indian religions designed to obtain discipline and control over the body and mind. In its classical contexts, yoga could refer to any one of a whole variety of such self-disciplinary practices. In India, yoga transcended sectaria…
Yttrium is not itself a rare earth element; however, its history is closely tied to that of the rare earths, and its chemical properties are similar to those of the members of that family. It also occurs in close association in nature with the rare earths. Yttrium was the first new element to be identified in the complex mineral called ytteriteytterite (now known as gadolinitegadolinite), discover…
Zebras are members of the horse family (Equidae) that inhabit tropical grasslands (savannas) in much of sub-Saharan Africa. Three of the seven species of equids are zebras. Zebras are herd-living social ungulates (hoofed mammals) recognized by a black-and-white (or cream or yellowish) striped coat, short erect mane, and a tail averaging about 18 in (0.5 m) long. The body length of a zebra is about…
One of the most important scholars of Zen Buddhism, Daisetz Suzuki, cogently explained the origins of Zen Buddhism in 1959: For several centuries in China, it was thought that Buddhism was a form of Daoism returning from India along the Silk Roads. Bernard Faure relates: "At the end of his life Laozi, in the guise of the Buddha, was said to have departed to the west to convert the barbarian…
Zero is often equated with "nothing," but that is not a good analogy. Zero can be the absence of a quality, but it can also be a starting point, such as 0° on a temperature scale. In a mathematical system, zero is the additive identity. It is a number which can be added to any given number to yield a sum equal to the given number. Symbolically, it is a number 0, such that a + …
The historians of nationalism have reached a consensus that modern nationalism began as a secular movement, but almost all its varieties were affected by an undertow of older religious sentiments and loyalties. In many of the nationalisms (for example, in the battles between Greeks and Turks in the second decade of the nineteenth century or in the quarrel between Catholics and Protestants in North…
The term zodiacal light is used to describe a faint, glowing band of light that occasionally appears near the eastern or western horizon, which is caused by reflection of sunlight from tiny dust particles in the solar system. Our solar system can be pictured as a huge disk, with the planets, their moons, and asteroids mostly orbiting in or near the same plane. If you look at the sky some evening w…
Zoonoses are diseases caused in humans by bacteria, viruses, parasites, and fungi that have been transmitted from animals, reptiles, or birds to people. Because many of the microorganisms that cause zoonotic disease are normal inhabitants of domestic animals and birds, people who are involved in agriculture and those who work in food processing plants can be at risk for infection. Prevention of su…
Zooplankton are small animals that occur in the water column of either marine and freshwater ecosystems. Zooplankton are a diverse group defined on the basis of their size and function, rather than on their taxonomic affinities. Most species in the zooplankton community fall into three major groups—Crustacea, Rotifers, and Protozoas. Crustaceans are generally the most abundant, especially t…