- 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.
The theory that explains the three major interactions of elementary particle physics—the strong interaction responsible for nuclear forces, the weak interaction responsible for radioactive decay, and the electromagnetic interaction—in terms of a common physical picture. The model for this picture is quantum electrodynamics, the fundamental theory underlying electromagnetism. In that theory, electrons, viewed as structureless elementary constituents of matter, interact with photons, structureless elementary particles of light. The standard model extends quantum electrodynamics to explain all three interactions of subnuclear physics in terms of similar basic constituents.
Industry:Science
The magnetic field observed at the Earth's surface is produced by internal and external sources. The internal component originates in the liquid outer core, where large convection cells in the iron-nickel alloy work much like a dynamo to produce an approximately dipolar field. The north and south magnetic poles are aligned roughly with the spin axis as a result of the mechanical interaction between the Earth's rotation and core convection. The magnetic field produced outside the core is electromagnetically filtered by the intervening mantle. While the mantle comprises mainly silicate minerals such as olivine and pyroxene, it possesses appreciable electrical conductivity.
Industry:Science
The study of systems consisting of arbitrary sets of elements of unspecified type, together with certain operations satisfying prescribed lists of axioms. Abstract algebra has been developed since the mid-1920s and has become a basic idiom of contemporary mathematics. In contrast to the earlier algebra, which was highly computational and was confined to the study of specific systems generally based on real and complex numbers, abstract algebra is conceptual and axiomatic. A combination of the theories of abstract algebra with the computational speed and complexity of computers has led to significant applications in such areas as information theory and algebraic geometry.
Industry:Science
The modern theory of matter, of electromagnetic radiation, and of the interaction between matter and radiation; also, the mechanics of phenomena to which this theory may be applied. Quantum mechanics, also termed wave mechanics, generalizes and supersedes the older classical mechanics and Maxwell's electromagnetic theory. Atomic and subatomic phenomena provide the most striking evidence for the correctness of quantum mechanics and best illustrate the differences between quantum mechanics and the older classical physical theories. Quantum mechanics is needed to explain many properties of bulk matter, for instance, the temperature dependence of the specific heats of solids.
Industry:Science
The removal of one or more components from a mixed system. Usually the components being removed are impurities or are considered less valuable than the material from which they are stripped. Examples of stripping operations are (1) the removal of overburden from a deposit of coal or ore, (2) the removal of color from a dyed fabric using a reactive agent, (3) the removal of an organic or a metallic coating from a solid surface, (4) the removal of a dissolved component from a liquid by extraction using a second liquid which is insoluble in the first, and (5) the removal of a volatile component from a liquid by vaporization. Only stripping by vaporization will be covered here.
Industry:Science
The study of life history as recorded by fossil remains. The term fossil, from the Latin “<i>fossilis</i>” (digging; dug up), originally referred to a variety of objects dug from the Earth, some of which were believed to be supernatural substances imbued with mystical powers. However, in a modern context, fossils can be defined as recognizable remains or traces of activity of prehistoric life. This broad definition takes in a diversity of ancient remains, but specifically excludes inorganic, mineralized structures, even those that spuriously resemble life forms (for example, dendritic patterns of manganese crystals: dendrites), sometimes termed pseudofossils (false fossils).
Industry:Science
The term glauconite as currently used has a twofold meaning. It is used as both a mineralogic and morphologic term. The mineral glauconite is defined as an illite type of clay mineral. It is dioctahedral with considerable replacement of aluminum by iron and magnesium. Structural substitutions result in a charge deficiency in both the tetrahedral and octahedral sheets, and interlayer cations seem to balance both of these charges. Calcium and sodium as well as potassium are the interlayer cations. A fundamental characteristic of glauconite is that the unit cell is composed of a single silicate layer rather than the double layer of most other dioctahedral micas.
Industry:Science
The movement of passengers and cargo by aircraft such as airplanes and helicopters. Air transportation has become the primary means of common-carrier traveling. Greatest efficiency and value are obtained when long distances are traveled, high-value payloads are moved, immediate needs must be met, or surface terrain prevents easy movement or significantly raises transport costs. Although the time and cost efficiencies obtained decrease as distance traveled is reduced, air transport is often worthwhile even for relatively short distances. Air transportation also provides a communication or medical link, which is sometimes vital, between the different groups of people being served.
Industry:Science
The name, literally translated as “beside the animals,” coined by William Johnson Sollas (1849–1936) for a phylum (later subkingdom) of animals comprising sponges, which, he believed, evolved independently of other multicellular animals (Enterozoa or Eumetazoa). Erection of a separate subkingdom, the Parazoa, for the sponges was based on the perceived uniqueness of the sponge body plan—the lack of differentiated tissues, nervous system, and terminal differentiation of cells—and the remarkable similarity between sponge choanocytes (collar cells) and unicellular eukaryotes called choanoflagellates. In addition, much importance was given to the hypothesis of “germ layer inversion.”
Industry:Science
The printed circuit board (PCB) has been in use for over a century, but it is still one of the most important parts of electronic devices, as the circuitry links all components together into an economical and efficiently integrated system. Once called printed wiring since they were first used to replace hand wiring in early telephone switchboards and radios, printed circuit boards are now ubiquitous. The printed circuit board consists of patterned arrays of conductors, such as copper, that are held onto and within dielectric materials, such as epoxy. But many other materials are used with dozens of processes to produce a myriad of circuit types that enable thousands of products.
Industry:Science
