- 行业: Printing & publishing
- Number of terms: 178089
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- 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.
The bright star in the southwest corner of the constellation Orion (apparent magnitude +0.12), also referred to as β Orionis. It is a blue-white supergiant of spectral type B8, one of the most luminous stars known. Its intrinsic brightness is estimated to be more than 50,000 times that of the Sun. Rigel is a very young star by stellar standards, with such an enormous rate of energy output that its life span is only a few million years. By comparison, the Sun is approximately 5 × 10<sup>9</sup> years old, and is still only half way through its main-sequence evolution. Rigel is the brightest member of the Orion OB1 Association, a large molecular cloud complex in which active star formation is currently taking place. In addition to its high luminosity, Rigel has a photosphere which is so large that if the star were placed where the Sun is, it would almost fill the orbit of Mercury.
Industry:Science
The branch of mathematics dealing with two fundamental operations, differentiation and integration, which are carried out on functions. The subject, as traditionally developed in college textbooks, is partly an elementary development of the purely theoretical aspects of these operations and their interrelation, partly a development of rules and formulas for applying calculus to the standard functions which arise in algebra and trigonometry (with exponentials and logarithms included), and partly a collection of applications to problems of geometry, physics, chemistry, engineering, economics, and perhaps a few other subjects.
Industry:Science
The application of mathematical methods to the study of complex human physical systems. A system is an arrangement or collection of objects that operate together for a common purpose. The objects may include machines (mechanical, electronic, or robotic), humans (individuals, organizations, or societal groups), and physical and biological entities. Everything excluded from a system is considered to be part of the system's environment. A system functions within its environment. Examples of systems include the solar system, a regional ecosystem, a nation's highway system, a corporation's production system, an area's hospital system, and a missile's guidance system. A system is analyzed so as to better understand the relationships and interactions between the objects that compose it and, where possible, to develop and test strategies for managing the system and for improving its outcomes.
Industry:Science
The four divisions of the year based upon variations of sunlight intensity (solar energy per unit area at the Earth's surface) at local solar noon (noontime) and daylight period. The variations in noontime intensity and daylight period are the result of the Earth's rotational axis being tilted 23°.5 from the perpendicular to the plane of the Earth's orbit around the Sun. The direction of the Earth's axis with respect to the stars remains fixed as the Earth orbits the Sun. If the Earth's axis were not tilted from the perpendicular, there would be no variation in noontime sunlight intensity or daylight period and no seasons.
Industry:Science
The examination of the ecology of interacting plants and animals by using an evolutionary, holistic perspective. Plant–animal interactions can take many forms. For example, the chemistry of defensive compounds of a plant species may be altered by natural-selection pressures resulting from the long-term effects of herbivores. Also, the physiology of modern herbivores may be modified from that of thousands of years ago as adaptations for the detoxification or avoidance of plant defensive chemicals have arisen. Other examples of plant–animal interactions include pollination biology, fruit and seed dispersal ecology, herbivory on plants by invertebrates (such as insects) and vertebrates (such as ungulates), ant–plant interactions, the ecology and evolution of carnivorous plants, and community and ecosystem patterns of animal distributions resulting from the availability of plant resources.
Industry:Science
The Earth's magnetic field has reversed polarity hundreds of times. That is, at different times in Earth's past, a compass would have pointed south instead of north. Recognition that the geomagnetic field has repeatedly reversed polarity played a key role in the revolution that transformed the geological sciences in the 1960s—the acceptance of the theory of plate tectonics. It is generally accepted that the geomagnetic field is generated by motion of electrically conducting molten metal in Earth's outer core. However, the mechanism by which the field decays and reverses polarity remains one of the great unknowns in geophysics.
Industry:Science
The exploitation of placer mineral deposits for their valuable heavy minerals. Placer mineral deposits consist of detrital natural material containing discrete mineral particles. They are formed by chemical and physical weathering of in-place heavy minerals, which are then concentrated through the action of wind or moving water. This concentration can be done through wave and current action in the ocean (beach and offshore placers), glacial action (moraine placers), wind action removing the lighter material (eolian placers), or the action of running water (stream placers). Stream placers are the most important of these deposits because of their common occurrence and their highly efficient concentration mechanisms. Marine placers, primarily beach placers, are the next most economically important, with the potential of offshore placers being the most recent to be recognized and developed.
Industry:Science
The first cell layers that appear in the development of all animals, and from which the embryo body and extraembryonic membranes (when present) are constructed. The cells of the early embryo (the blastula) are organized into supracellular units, the germ layers. These are more or less distinct anatomically but do not necessarily have sharp boundaries of demarcation, in part because one layer gives rise to another. Germ layers are universal among animal embryos; they are an efficient method for establishing discontinuities of architectural importance and for setting aside what will become lineages of cells with different fates.
Industry:Science
The conversion of coal or coal char to gaseous products by reaction with steam, oxygen, air, hydrogen, carbon dioxide, or a mixture of these. Products consist of carbon monoxide, carbon dioxide, hydrogen, methane, and some other gases in proportions dependent upon the specific reactants and conditions (temperatures and pressures) employed within the reactors, and the treatment steps which the gases undergo subsequent to leaving the gasifier. Similar chemistry can also be applied to the gasification of coke derived from petroleum and other sources. The reaction of coal or coal char with air or oxygen to produce heat and carbon dioxide could be called gasification, but it is more properly classified as combustion. The principal purposes of such conversion are the production of synthetic natural gas as a substitute gaseous fuel and synthesis gases for production of chemicals and plastics.
Industry:Science
The formation of new individuals, which may occur by asexual or sexual methods. In the asexual methods, which occur mainly among the lower animals, the offspring are derived from a single individual. Sexual methods are general throughout the animal kingdom, with offspring ordinarily derived from the paired union of special cells, the gametes, from two individuals. Basic to all processes of reproduction is the origin of the new individual from one or more living cells of the parent or parents. There has been no acceptable demonstration of the origin of a new living organism from other material than preexisting living cells.
Industry:Science
