- 行业: Printing & publishing
- Number of terms: 178089
- Number of blossaries: 0
- Company Profile:
McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A wing is the primary lift-generating surface of an aircraft. Adaptive wings—also known as smart, compliant, intelligent, morphing, controllable, and reactive wings—are lifting surfaces that can change their shape in flight to achieve optimal performance at different speeds, altitudes, and ambient conditions. There are different levels of sophistication, or intelligence, that can be imbued in a particular design.
Industry:Science
A wing with special streamwise sections, or airfoils, which provide substantial delays in the onset of the adverse aerodynamic effects which usually occur at high subsonic flight speeds.
Industry:Science
A wood product in which the grain structure of the original wood is drastically altered. Composition board may be divided into several types. When wood serves as the raw material for chemical processing, the resultant product may be insulation board, hardboard, or other pulp product. When the wood is broken down only by mechanical means, the resultant product is particle board. Because composition board can use waste products of established wood industries and because there is a need to find marketable uses for young trees, manufacture of composition board is one of the most rapidly developing portions of the wood industry.
Industry:Science
A wood product in which thin sheets of wood are glued together, grains of adjacent sheets being at right angles to each other in the principal plane. Because of this cross-grained orientation, mechanical properties are less directional than those of natural lumber and more dimensionally stable. Originally developed to replace wide wood boards that had been sawed directly from large logs, plywood was manufactured from logs not suitable for other purposes. It has since found such widespread use that tree farms are now cultivated specifically to yield logs suitable for processing into sheets for plywood. The softwood plywood capacity in the United States in 1997 was 12.5 million cubic meters. Southern pine represents the largest segment of this market.
Industry:Science
A worldwide disease caused by infection with the bacterium <i>Francisella tularensis</i>, which affects multiple animal species, including humans. Tularemia cases have been reported from North America, Europe, Russia, China, and Japan. In the winter, infection in adult humans occurs frequently from skinning infected rabbits, hares, muskrats, or beavers bare-handed; in the summer, infections occur in both adults and children from transmission of the bacteria through the bites of ticks or deer flies.
Industry:Science
A worldwide order of diurnal predacious birds without obvious affinities to other orders of birds. They are not closely related to the owls; any similarities between these two orders are the result of convergence.
Industry:Science
A young low-mass star characterized by variability, the presence of hydrogen emission lines, and association with dark or bright nebulae. T Tauri stars are named after a variable star in the constellation Taurus that exhibits particularly strong hydrogen emission. They were originally believed to be ordinary field stars passing through and interacting with a star-forming nebula. Their association with these regions was soon discovered to be more than coincidental, however, and they are now identified with the earliest phase of young stellar evolution, in which a star emerges from its natal molecular cloud to be detectable at visible wavelengths. T Tauri stars with very strong emission lines are designated classical T Tauri stars; their counterparts with reduced hydrogen emission are known as weak-line T Tauri stars. In addition to the original defining properties, T Tauri stars are generally accompanied by excess x-ray, ultraviolet, infrared, and millimeter-wave emission that arises from an accreting circumstellar disk of dust and gas.
Industry:Science
A young, elongate ocean basin on the west coast of Mexico. It is flanked on the west by the narrow mountainous peninsula and continental shelf of Baja California, while the eastern margin has a wide continental shelf and coastal plain. The floor of the gulf consists of a series of basins 3300–12,000 ft (1000–3600 m) deep, whereas the northern gulf is dominated by a broad shelf which is the result of deltaic deposition from the Colorado River. The structural depression of the gulf continues northward into the Imperial Valley of California, which is cut off from the ocean by the delta of the Colorado River.
Industry:Science
A zone of forest vegetation encircling the Northern Hemisphere between the arctic-subarctic tundras in the north and the steppes, hardwood forests, and prairies in the south. The chief characteristic of the taiga is the prevalence of forests dominated by conifers. The taiga varies considerably in tree species from one major geographical region to another, and within regions there are distinct latitudinal subzones. The dominant trees are particular species of spruce, pine, fir, and larch. Other conifers, such as hemlock, white cedar, and juniper, occur locally, and the broad-leaved deciduous trees, birch and poplar, are common associates in the southern taiga regions. Taiga is a Siberian word, equivalent to “boreal forest.”
Industry:Science
A. S. Romer wrote that mammalian paleontologists seemed to think that “mammalian evolution consisted of parent molar teeth giving birth to filial molar teeth, and so on down through the ages.” It is true that most Mesozoic (250–65 million years ago (mya)) mammals are known solely from their teeth; the hardest bones in the skeleton, teeth are preserved in many sedimentary environments in which the rest of the animal is destroyed.
For this reason, the extraordinary quality of fossil preservation in the Jehol Group, a series of richly fossiliferous lake deposits in northeastern China deposited between 135 and 120 million years ago, is significant to mammalian paleontologists. The fine-grained shales of the Jehol Group, deposited in a low-energy environment with no waves or strong currents, have preserved fragile insects, delicate plants, and most prominently the long-hypothesized feathers of dinosaurs discovered in the 1990s. Almost lost in this embarrassment of riches are the partial or complete skeletons of six genera of mammals, five of them new to science.
Industry:Science
