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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.
The process that led to the formation of the continents. The Earth's crust is distinctively bimodal in thickness. Oceanic crust is normally about 4 mi (7 km) thick, varying mainly with the temperature of the mantle beneath the sea-floor spreading ridges when the crust was formed. In contrast, the typical 22–25-mi (35–40-km) thickness of continental crust is controlled ultimately—through the agents of erosion, sedimentation, and isostatic adjustment—by sea level. Oceanic crust is formed at spreading ridges, continental crust at subduction zones. Both are recycled to the mantle, but oceanic crust, being less buoyant, is recycled about 30 times faster than continental crust. Consequently, continents, having a mean age of almost 2 billion years and a maximum age of 4 billion years, provide the only directly accessible record spanning most of Earth history. They are, however, structurally more complex than ocean basins because of their great antiquity and weak rheology.
Industry:Science
The measurement of the ratio of the charge induced on a conductor to the difference in potential between it and a neighboring conductor which induces the charge. In a multiconductor system there are capacitances between each pair of conductors. In general, these capacitances are functions of the total geometry, that is, the location of all of the conducting and dielectric bodies. When, as is usually true, only the capacitance between two conductors is of interest, the presence of other conductors is an undesirable complication. It is then customary to distinguish between two-terminal and three-terminal capacitors and capacitance measurements. In a two-terminal capacitor, either one of the conductors of primary interest surrounds the other (in which case the capacitance between them is independent of the location of other bodies except in the vicinity of the terminals); or the somewhat indefinite contributions of other conductors to the capacitance of interest are accepted.
Industry:Science
The science of the sea; including physical oceanography (the study of the physical properties of sea water and its motion in waves, tides, and currents), marine chemistry, marine geology, and marine biology. The need to know more about the impact of marine pollution and possible effects of the exploitation of marine resources, together with the role of the ocean in possible global warming and climate change, means that oceanography is an important scientific discipline. Improved understanding of the sea has been essential in such diverse fields as fisheries conservation, the exploitation of underwater oil and gas reserves, and coastal protection policy, as well as in national defense strategies. The scientific benefits include not only improved understanding of the oceans and their inhabitants, but important information about the evolution of the Earth and its tectonic processes, and about the global environment and climate, past and present, as well as possible future changes.
Industry:Science
The sensations caused by dehydration, the continuing loss of fluid through the skin and lungs and in the urine and feces while there is no water intake into the body. Thirst becomes more and more insistent as dehydration worsens. Water and electrolytes are needed to replace losses, and an adequate intake of sodium as well as water is important for maintaining blood volume. Herbivores and human vegetarians, whose diets lack sodium, have a natural appetite for sodium; however, severe sodium deficiency in carnivorous animals and humans can result in the development of a well-marked sodium appetite as well. Water intake varies considerably between individuals and depends on climate, custom, and diet. Reproduction affects drinking behavior; fluid intake increases during pregnancy and especially during lactation. Normally, the amounts of water drunk and taken in food are more than enough to maintain hydration of the body, and the usual mixed diet provides all the electrolytes required.
Industry:Science
The process of biological and organic change within the plant kingdom by which the characteristics of plants differ from generation to generation. Understanding of the course of plant evolution is based on several lines of evidence. The main levels (grades) of evolution have long been clear from comparisons among living plants, but the fossil record has been critical in dating evolutionary events and revealing extinct intermediates between modern groups, which are separated from each other by great morphological gaps (evolutionary changes in many characters). Plant evolution has been clarified by cladistic methods for estimating relationships among both living and fossil groups. These methods attempt to reconstruct the branching of evolutionary lines (phylogeny) by using shared evolutionary innovations (for example, presence of a structure not found in other groups) as evidence that particular organisms are descendants of the same ancestral lineage (a monophyletic group, or clade).
Industry:Science
The name given to the monoclinic lithium pyroxene LiAl(SiO<sub>3</sub>)<sub>2</sub>. Spodumene commonly occurs as white to yellowish prismatic crystals, often with a “woody” appearance, exhibiting the 87° pyroxene (110) cleavages. It is easily identified during heating in a flame by the red color given off, accompanied by a marked swelling of the fragment. Spodumene usually contains an appreciable quantity of hydrogen substituting for lithium. At 720°C (1330°F), spodumene inverts to a tetragonal form, β-spodumene, which is accompanied by a 30% increase in volume. Spodumene is capable of forming immense crystals in nature. A single crystal 47 ft (14.3 m) in length and 5 ft (1.5 m) in diameter, as well as others almost as large, has been found at the Etta mine in South Dakota. This implies the remarkable ability of a single crystal to replace a large variety of preexisiting minerals and yet maintain the integrity of a single crystal, a crystal growth unequaled elsewhere in nature.
Industry:Science
The systematic study of tensors which led to an extension and generalization of vectors, begun in 1900 by two Italian mathematicians, G. Ricci and T. Levi-Civita, following G. F. B. Riemann's proposal concerning a generalization of euclidean geometry. The principal aim of the tensor calculus (absolute differential calculus) is to construct relationships which are generally covariant in the sense that these relationships or laws remain valid in all coordinate systems. The differential equations for the geodesics in a riemannian space are covariant expressions; they yield a description of the geodesics which is valid for all coordinate systems. On the other hand, Newton's equations of motion require a preferred coordinate system for their description, namely, one for which force is proportional to acceleration (an inertial frame of reference). Thus Albert Einstein was led to a study of riemannian geometry and the tensor calculus in order to construct the general theory of relativity.
Industry:Science
The spatial distribution at any particular moment of the individuals of a species of plant or animal. Under natural conditions organisms are distributed either by active movements, or migrations, or by passive transport by wind, water, or other organisms. The act or process of dissemination is usually termed dispersal, while the resulting pattern of distribution is best referred to as dispersion. Dispersion is a basic characteristic of populations, controlling various features of their structure and organization. It determines population density, that is, the number of individuals per unit of area, or volume, and its reciprocal relationship, mean area, or the average area per individual. It also determines the frequency, or chance of encountering one or more individuals of the population in a particular sample unit of area, or volume. The ecologist therefore studies not only the fluctuations in numbers of individuals in a population but also the changes in their distribution in space.
Industry:Science
The more than 175 legume species that constitute the tribe Loteae are found worldwide, except for the very cold arctic regions and the lowland tropical areas of Southeast Asia and South and Central America. Approximately three-quarters of all species in the genus <i>Lotus</i> are Old World, yet only four Old World species receive major attention: <i>L. corniculatus</i> (broadleafed birdsfoot trefoil), <i>L. glaber</i> (narrowleafed birdsfoot trefoil), <i>L. uliginosus</i> (big trefoil), and <i>L. japonicus</i>. Several species of <i>Lotus</i> are used as forage legumes to provide a high-quality feed source for grazing livestock. Some <i>Lotus</i> species have utility as tools for advancing molecular biology. <i>Lotus corniculatus</i> has the most agricultural importance and the widest distribution. Its native range extends from Scandinavia across lowland and high alpine regions of central Europe to Asia Minor and Africa, and it occurs as naturalized populations in North and South America.
Industry:Science
The scientific study of the processes and impacts of ice sheets, valley glaciers, and other ice masses on the Earth's surface, both on land and in ocean basins. The processes include understanding how ice masses move, erode, transport, and deposit sediment. The impacts on glaciated landscapes are enormous in terms of topographic change and floral and faunal modification. In those areas peripheral to glaciated areas, drainage patterns are altered, and climatic, vegetation, and soil conditions are severely changed. In addition, glacial geology involves studying the causes of glaciation, the chronology of glaciation in geologic time (the retreat and advance of ice masses at all scales), glacial stratigraphy, sea-level change, and how glaciations affect oceans, climate, flora, fauna, and human society globally. Closely allied to glacial geology are studies into the physics of ice masses (glaciology), global climatology (paleoclimatology), and paleoenvironmental reconstructions (paleoecology).
Industry:Science
