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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.
A property exhibited by certain metals, alloys, and compounds of the transition (iron group), rare-earth, and actinide elements in which, below a certain temperature called the Curie temperature, the atomic magnetic moments tend to line up in a common direction. Ferromagnetism is characterized by the strong attraction of one magnetized body for another, a phenomenon known before 600 <small>B.C.</small>
Industry:Science
A property exhibited by substances which, when placed in a magnetic field, are magnetized parallel to the field to an extent proportional to the field (except at very low temperatures or in extremely large magnetic fields). Paramagnetic materials always have permeabilities greater than 1, but the values are in general not nearly so great as those of ferromagnetic materials. Paramagnetism is of two types, electronic and nuclear.
Industry:Science
A property of a magnetic circuit analogous to resistance in an electric circuit.
Industry:Science
A property of a system, or part of a system, that indicates how the system reacts to stimuli. The stimuli can be external (that is, an input signal) or a change in an element in the system. Thus, sensitivity can be interpreted as a measure of the variation in some behavior characteristic of the system that is caused by some change in the original value of one or more of the elements of the system.
Industry:Science
A property of biological materials that imparts coloration. Hence, pigmentation determines the quantity and quality of reflected visible light. The characteristics of light returning from living matter are a function of its chemical and physical properties and, therefore, not only are due to pigments proper but can be of structural origin as well.
Industry:Science
A property possessed by some metals, alloys, and salts of transition elements in which the atomic magnetic moments, at sufficiently low temperatures, are arranged in a spiral or helix. It may be seen from the <b>illustration</b> that simple antiferromagnets and ferromagnets can be considered as nonconical helimagnets with helical angles φ of 180 and 0°, respectively. In the same way, nonconical helimagnets may be considered as conical helimagnets with cone angle θ of 0°. Some typical helimagnets are listed in the <b>table</b>. The magnetic structures have been detected by neutron diffraction.
Industry:Science
A property possessed by some metals, alloys, and salts of transition elements in which the atomic magnetic moments, at sufficiently low temperatures, form an ordered array which alternates or spirals so as to give no net total moment in zero applied magnetic field. <b>Figure 1</b> shows the simple antiparallel arrangement of manganese moments at temperatures below 72 K in the unit cell of manganese fluoride (MnF<sub>2</sub>). The most direct way of detecting such arrangements is by means of neutron diffraction.
Industry:Science
A proposal for a unified theory of all interactions, including gravity. At present, the strong, weak, and electromagnetic interactions are accounted for within the framework of the standard model. This model correctly describes experiments up to the highest energies performed so far, and gives a complete description of the elementary particles and their interactions down to distances of the order of 10<sup>−18</sup> m. Nevertheless, it has serious limitations, and attempts to overcome them and to unify the forces of nature have been only partly successful. Moreover, these attempts have left standing fundamental difficulties in reconciling gravitation and the laws of quantum mechanics. Superstring theory represents an ambitious program to unify all of the interactions observed in nature, including gravitation, in a theory with no unexplained parameters. In other words, this theory, if successful, should be able to account for all of the particles observed in nature and their interactions.
Industry:Science
A proposed order of the Peracarida established for two small crustacean species, <i>Hirsutia bathyalis</i> and <i>Mictocaris halope</i> (see <b>illus.</b>). The two species share many features common to other peracaridans but differ sufficiently to justify their assignment to a distinct order with two monotypic families. Common peracaridan features include a brood pouch formed by basal lamellae of the perepods (oöstegites) in the female; a small movable process (lacinia mobilis) on the mandible; free thoracic somites not fused to a carapace shield; a single maxilliped of typical peracarid form; and partially immobile pereopodal basal segments.
Industry:Science
A proposition arrived at by the methods of logical deduction from a set of basic postulates or axioms accepted as primitive and therefore not subject to deductive proof. So long as a theorem is part of a purely formal system, it is not meaningful to speak about the “truth” of a theorem but only about its “correctness.” It becomes true when it, or its consequences, can be shown to be in accord with observable facts. The classic example of a system of theorems is afforded by Euclid's system of geometry, which is now recognized to have only a purely formal character, although it was formerly considered to be meaningful to ask whether Euclid's geometry was “true.”
Industry:Science
