- 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.
An igneous rock in which carbonate minerals make up at least half the volume. Individual occurrences of carbonatite are not numerous (about 330 have been recognized) and generally are small, but they are widely distributed. Carbonatites are scientifically important because they reveal clues concerning the composition and thermal history of the Earth's mantle. Economically, carbonatites provide important mines for some mineral commodities and are virtually the only sources of a few.
Industry:Science
An illness produced by the exotoxin of <i>Clostridium botulinum</i> and occasionally other clostridia, and characterized by paralysis and other neurological abnormalities. There are seven principal toxin types involved (A–G); only types A, B, E, and F have been implicated in human disease. Types C and D produce illness in birds and mammals. Strains of <i>C. barati</i> and <i>C. butyricum</i> have been found to produce toxins E and F and have been implicated in infant botulism. There is serologic cross-reactivity between <i>C. botulinum</i> and <i>C. sporogenes</i> and <i>C. novyi.</i> Botulinal toxin is among the most potent poisons known; it has a heavy chain (molecular weight about 100,000) and a light chain (about 50,000) joined by a disulfide bond.
Industry:Science
An illness that follows an upper respiratory infection with the group A streptococcus (<i>Streptococcus pyogenes</i>) and is characterized by inflammation of the joints (arthritis) and the heart (carditis). Arthritis typically involves multiple joints and may migrate from one joint to another. The carditis may involve the outer lining of the heart (pericarditis), the heart muscle itself (myocarditis), or the inner lining of the heart (endocarditis). A minority of affected individuals also develop a rash (erythema marginatum), nodules under the skin, or Sydenham's chorea (a neurologic disorder characterized by involuntary, uncoordinated movements of the legs, arms, and face). These clinical manifestations may occur singly or in combination, and although most disappear completely, damage to heart valves may be permanent and progressive, leading to severe disability or death from rheumatic heart disease years after the initial attack.
Industry:Science
An imaginary being whose action appears to contradict the second law of thermodynamics. The properties of bulk systems are explained in terms of contributions from their constituent molecules. The same, presumably, should be true of certain grand properties of nature, and in particular the second law of thermodynamics, which identifies the natural direction of change with the direction of increasing entropy. The statistical basis of this law, in which entropy is identified with molecular chaos, was established largely through the work of L. Boltzmann. However, there has always been a certain degree of discomfort associated with the acceptance of the law, particularly in relation to the time reversibility of physical laws and the role of molecular fluctuations. In 1867, J. C. Maxwell considered, in this connection, the action of “a finite being who knows the paths and velocities of all the molecules by inspection.” This being was later referred to as a demon by Lord Kelvin, and the usage has been generally adopted.
Industry:Science
An imaginary sphere of infinite radius centered either on an observer or at the center of the Earth. We imagine that the stars and planets are attached to the inside surface of the celestial sphere. Standing outside on a clear moonless night far from city lights, it is easy to imagine that one is at the center of such a sphere and that the stars and planets are attached to its inside surface.
Industry:Science
An imaging technique which uses an array of detectors to collect information from a beam that has passed through an object (for example, a portion of the human body). The information collected is then used by a computer to reconstruct the internal structures, and the resulting image can be displayed—for example, on a television screen.
Industry:Science
An immunologically active protein or polysaccharide present in some but not all individuals in a particular species. These substances initiate the formation of antibodies when introduced into other individuals of the species that genetically lack the isoantigen. Like all antigens, they are also active in stimulating antibody production in heterologous species. The ABO, MN, and Rh blood factors in humans constitute important examples; thus, elaborate precautions for typing are required in blood transfusions.
Industry:Science
An impairment in the performance of voluntary actions despite intact motor power and coordination, sensation and perception, and comprehension. The apraxic person knows the act to be carried out, and has the requisite sensory-motor capacities; yet performance is defective. The abnormality is highlighted when the act must be performed on demand and out of context. The individual may perform normally in such activities as hammering or tooth brushing performed with the object in hand, especially in a natural situation, but will often fail when required to pantomime such acts.
Industry:Science
An impairment in the recognition of stimuli in a particular sensory modality. True agnosias are associative defects, where the perceived stimulus fails to arouse a meaningful state. An unequivocal diagnosis of agnosia requires that the recognition failure not be due to sensory-perceptual deficits, to generalized intellectual impairment, or to impaired naming (as in aphasia). Because one or more of these conditions frequently occur with agnosia, some clinical scientists have questioned whether pure recognition disturbances genuinely exist; but careful investigation of appropriate cases has affirmed agnosia as an independent entity which may occur in the visual, auditory, or somesthetic modalities.
Industry:Science
An important central lymphoid organ in the neck or upper thorax of all vertebrates from elasmobranchs to mammals. The most primitive representatives of vertebrates which have been shown to possess this organ are the cyclostomes <i>Eptatretus stoutii</i> (California hagfish) and <i>Petromyzon marinus</i> (sea lamprey).
Industry:Science
