(from the article "technology, history of") Assuming that the use of nuclear weapons can be averted, world civilization will have to come to grips with the population problem in the next few decades if life is to be tolerable on planet Earth in the 21st century. The problem can be tackled in two ways, both drawing ...
(from the article "population ecology") As stated above, populations rarely grow smoothly up to the carrying capacity and then remain there. Instead, fluctuations in population numbers are the norm. In a few species, such as snowshoe hares, lemmings, lynx, and Arctic foxes, populations show regular cycles of increase and decrease spanning a number of years ...
(from the article "Hardy-Weinberg law") The science of population genetics is based on this principle, which may be stated as follows: in a large, random-mating population, the proportion of dominant and recessive genes present tends to remain constant from generation to generation unless outside forces act to change it. In such a way even the ...
(from the article "Intrinsic rate of increase (r) calculated for populations of species that differ greatly in their potential for the rate of population growth") Kenya's accelerating population growth from the early 1960s to the early 1980s seriously constrained the country's social and economic development. During the first quarter of the 20th century, the total population was fewer than four million, largely because of famines, wars, and disease. By the late 1940s the population had ...
(from the article "Stellar populations") in astronomy, two broad classes of stars and stellar assemblages defined in the early 1950s by the German-born astronomer Walter Baade. The members of these stellar populations differ from each other in various ways, most notably in age, chemical composition, and location within galactic systems.major reference
in physics, the redistribution of atomic energy levels that takes place in a system so that laser action can occur. Normally, a system of atoms is in temperature equilibrium and there are always more atoms in low energy states than in higher ones. Although absorption and emission of energy is ... [2 Related Articles]
(from the article "statistics") The most fundamental point and interval estimation process involves the estimation of a population mean. Suppose it is of interest to estimate the population mean, mu, for a quantitative variable. Data collected from a simple random sample can be used to compute the sample mean, x, where ...
(from the article "population") An important and often misunderstood characteristic of human populations is the tendency of a highly fertile population that has been increasing rapidly in size to continue to do so for decades after the onset of even a substantial decline in fertility. This results from the youthful age structure of such ...
(from the article "statistics") For qualitative variables, the population proportion is a parameter of interest. A point estimate of the population proportion is given by the sample proportion. With knowledge of the sampling distribution of the sample proportion, an interval estimate of a population proportion is obtained in much the same fashion as for ...
(from the article "population") Perhaps the most fundamental of these characteristics is the age distribution of a population. Demographers commonly use population pyramids to describe both age and sex distributions of populations. A population pyramid is a bar chart or graph in which the length of each horizontal bar represents the number (or percentage) ...
(from the article "apartheid") ...and political and economic discrimination against nonwhites. The implementation of apartheid, often called "separate development" since the 1960s, was made possible through the Population Registration Act of 1950, which classified all South Africans as either Bantu (all black Africans), Coloured (those of mixed race), or white. A fourth category-Asian (Indian ...
(from the article "population ecology") A life history is the sequence and timing of events that occur between birth and death. Populations from different parts of the geographic range that a species inhabits may exhibit marked variations in their life histories (see above Genetic variation within local populations). The patterns of variation seen within and ...
in astronomy, two broad classes of stars and stellar assemblages defined in the early 1950s by the German-born astronomer Walter Baade. The members of these stellar populations differ from each other in various ways, most notably in age, chemical composition, and location within galactic systems. [6 Related Articles]
(from the article "Cameroon, history of") In French Cameroun the major question was the type and intensity of the relationship with France after independence. The first nationalist party, the Cameroon People's Union (UPC) led by Felix-Roland Moumie and Reuben Um Nyobe, demanded a thorough break with France and the construction of a socialist economy. French officials ...
(from the article "fascism") Fascists praised the Volk and pandered to populist anti-intellectualism. Nazi art criticism, for example, upheld the populist view that the common man was the best judge of art and that art that did not appeal to popular taste was decadent. Also populist was the Nazi propaganda theme ...
in U.S. history, politically oriented coalition of agrarian reformers in the Middle West and South that advocated a wide range of economic and political legislation in the late 19th century. [7 Related Articles]
(from the article "George II") ...on December 19 with his queen, Elizabeth. In March 1924 the Greek National Assembly voted the end of the monarchy and proclaimed Greece a republic. The king remained in exile until the conservative Populist Party, with the support of the army, gained control of the Assembly and declared the restoration ...
ancient Roman city that had originally been Etruscan and named Pupluna or Fufluna after the Etruscan wine god, Fufluns. It was situated on the western coast of central Italy on the Monte Massoncello Peninsula-the only large Etruscan city directly on the sea. The reason for the city's existence is found ...
(from the article "Roman law") 2. The populus Romanus, or the "people of Rome," collectively could acquire property, make contracts, and be appointed heir. Public property included the property of the treasury.
(from the article "poker") ...of brag in England (one of four card games about which Edmond Hoyle wrote) and pochen (its name meaning "to bluff") in Germany. From the latter the French developed a similar game called poque, first played in French America in 1803, when the Louisiana Purchase made New Orleans and its ...
(from the article "Albanian literature") A lone figure in the landscape of 20th-century Albanian literature is the poet Lasgush Poradeci (pseudonym of Llazar Gusho, of which Lasgush is a contraction). Breaking with tradition and conventions, he introduced a new genre with his lyrical poetry, which is tinged with mystical overtones. Writers in post-World War II ...
(from the article "chromatography") ...in their migration as they meander in and out of the pores by diffusion. Molecules of intermediate sizes show different rates of migration, depending on their size. In 1959 Per Flodin and Jerker Porath in Sweden developed cellulose polymeric materials that acted as molecular sieves for substances dispersed in liquids. ...
(from the article "Religion") ...Bishops, wrote to President Bush that the Israeli policies constituted "the most difficult situation in living memory for the Church in the Holy Land." In October, Interior Minister Avraham Poraz condemned incidents in which Jewish seminary students spat at Christian clergy, including Armenian Archbishop Nourhan Manougian, during processions through the ...
town, Junagadh district, Gujarat state, west central India, on the Arabian Sea. The birthplace of Mahatma Gandhi, it was controlled by the Jethwa Rajputs from about the 16th century. Porbandar was the capital of the former princely state of Porbandar (1785-1948) before it became a district. It is famous for ...
(from the article "Colombia") ...granitic Antioquia batholith (an exposed granitic intrusion), a tableland averaging some 8,000 feet (2,500 metres) above sea level. It is divided into two parts by the deep transverse cleft of the Porce River, which occupies the U-shaped valley in which is situated the expanding metropolis of Medellin, Colombia's second city. ...
vitrified pottery with a white, fine-grained body that is usually translucent, as distinguished from earthenware, which is porous, opaque, and coarser. The distinction between porcelain and stoneware, the other class of vitrified pottery material, is less clear. In China, porcelain is defined as pottery that is resonant when struck; in ... [19 Related Articles]
process of fusing a thin layer of glass to a metal object to prevent corrosion and enhance its beauty. Porcelain-enamelled iron is used extensively for such articles as kitchen pots and pans, bathtubs, refrigerators, chemical and food tanks, and equipment for meat markets. In architecture it serves as facing for ... [1 Related Articles]
(from the article "Capodimonte porcelain") ...range of commedia dell'arte characters are vivid creations, distinctive in the restrained use of soft colours and gold. But the decorative masterpiece of the Capodimonte factory is the Rococo "Porcelain Room" originally at the Villa Reale at Portici but moved to the Palazzo of Capodimonte in 1805. Executed between 1757 ...
(from the article "bioceramics") A large fraction of all fixed prostheses-e.g., crowns and inlays-are made of porcelain-fused-to-metal (PFM) cermets. These consist of a cast metal substrate, a metal oxide adhesion layer, and several layers of porcelain. The porcelain hides the metal while providing translucency and colour. It must be thermally compatible with the metal ...
hard, dense rock that takes its name from its resemblance to unglazed porcelain. Frequently porcellanite is an impure variety of chert containing clay and calcareous matter; when of this nature it is composed chiefly of silica (see chert and flint).
roofed structure, usually open at the sides, projecting from the face of a building and used to protect the entrance. It is also known in the United States as a veranda and is sometimes referred to as a portico. A loggia may also serve as a porch.
(from the article "ancient Rome") ...and their magistrates, the tribunes. Nevertheless, signs of the upheaval ahead are visible. For one, the long plebeian struggle against arbitrary abuse of magisterial power continued. A series of Porcian laws were passed to protect citizens from summary execution or scourging, asserting the citizen's right of appeal to the assembly ...
(from the article "meat processing") ...light from the surface of the meat (the meat appears pale). PSE meat is especially problematic in the pork industry. It is known to be stress-related and inheritable. A genetic condition known as porcine stress syndrome (PSS) may increase the likelihood that a pig will yield PSE meat.
(from the article "Andes Mountains") ...humid puna, or jalca, begins. Mountains become wider and smoother in appearance, while vegetation changes to heathland and trees. The altitude diminishes, and passes are much lower, as at Porculla Pass (7,000 feet) east of Piura.
any of 25 species of large, herbivorous, quill-bearing rodents active from early evening to dawn. All have short, stocky legs, but their tails range from short to long, with some being prehensile. The quills, or spines, take various forms depending on the species, but all are modified hairs embedded in ... [2 Related Articles]
any of the spiny, shallow-water fishes of the family Diodontidae, found in seas around the world, especially the species Diodon hystrix. They are related to the puffers and, like them, can inflate their bodies when provoked. [1 Related Articles]
(from the article "needlegrass") any of the grasses of the genus Stipa (family Poaceae), consisting of about 150 species with a sharply pointed grain and a long, threadlike awn (bristle). In some species, such as porcupine grass (Stipa spartea), the sharp grain may puncture the faces of grazing animals.
major tributary of the Yukon River, in northern Yukon Territory, Can., and northeastern Alaska, U.S. Discovered in 1842 by John Bell of the Hudson's Bay Company, the Porcupine rises in the Mackenzie Mountains of west central Yukon Territory and flows for 448 mi (721 km) in a great arc, first ...
(from the article "coconut palm") ...Mature palm leaves are used in thatching and weaving baskets. The fibrous, decay-resistant tree trunk is incorporated into the construction of huts; it is also exported as a cabinet wood called porcupine wood.
(from the article "coal") Coal density is controlled in part by the presence of pores that persist throughout coalification. Measurement of pore sizes and pore distribution is difficult; however, there appear to be three size ranges of pores: (1) macropores (diameter greater than 50 nanometres), (2) mesopores (diameter 2 to 50 nanometres), and (3) ...
(from the article "permafrost") ...in the north. Ice in the perennially frozen ground exists in various sizes and shapes and has definite distribution characteristics. The forms of ground ice can be grouped into five main types: (1) pore ice, (2) segregated, or Taber, ice, (3) foliated, or wedge, ice, (4) pingo ice, and (5) ...
(from the article "plant") ...opercula, peristome, stomata, and columella; elaters mixed with spores in capsule; capsule opening into 4 or more valves; between 6,000 and 9,000 species; representative genera include Porella, Frullania, Marchantia, Conocephalum, and Riccia.
(from the article "Beguines") One of the most remarkable Beguines was Marguerite Porete, who was burned for heresy in Paris in 1310. Her mystical work Miroir des simples ames (c. 1300; The Mirror of Simple Souls) is thought to be the greatest religious tract written in Old French.Christian mysticism
(from the article "logic, history of") ...on Leibniz' logic (1901) and an edition of Leibniz' previously unpublished writings on logic (1903) were very important events in the study of the history of logic. In Russia V.V. Bobyin (1886) and Platon Sergeevich Poretsky (1884) initiated a school of algebraic logic. In the United Kingdom a vast amount ...
(from the article "Mexico") A complex mechanism in which all major and most minor decisions rested in the hands of the president evolved during the first two decades of the Diaz regime, or Porfiriato. The success of the practice rested on self-interest; Diaz made it worthwhile for everyone to support the system. For the ...
any of about 100 species of marine fishes of the family Sparidae (order Perciformes). Porgies, sometimes called sea breams, are typically high-backed, snapper- or grunt-like fishes. They have a single dorsal fin, and their small mouths, equipped with strong teeth, can handle a diet of fishes and hard-shelled invertebrates. [1 Related Articles]
