- 行业: Printing & publishing
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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 term spectrum is applied to any class of similar entities or properties strictly arrayed in order of increasing or decreasing magnitude. In general, a spectrum is a display or plot of intensity of radiation (particles, photons, or acoustic radiation) as a function of mass, momentum, wavelength, frequency, or some other related quantity. For example, a beta-particle spectrum represents the distribution in energy or momentum of negative electrons emitted spontaneously by certain radioactive nuclides, and when radionuclides emit alpha particles, they produce an alpha-particle spectrum of one or more characteristic energies. A mass spectrum is produced when charged particles (ionized atoms or molecules) are passed through a mass spectrograph in which electric and magnetic fields deflect the particles according to their charge-to-mass ratios. The distribution of sound-wave energy over a given range of frequencies is also called a spectrum.
Industry:Science
The mineral species containing the CO<sub>3</sub><sup>2−</sup> unit as an essential structural and chemical component. Members are distinguished by chemical composition (type of metal cation and in some cases other anion present) and crystal structure. More than 200 varieties of carbonate minerals are known, but only a small number occur in abundance. Calcite (CaCO<sub>3</sub>) and dolomite (CaMg(CO<sub>3</sub>)<sub>2</sub>) are the most common species, occurring as the principal mineral components in limestone and Mg-rich limestone sedimentary rocks. Carbonate minerals exhibit limited stability at high temperature unless high carbon dioxide (CO<sub>2</sub>) pressure exists, which explains their occurrence dominantly in environments near the Earth's surface and in sedimentary rocks. However, important occurrences in metamorphic rocks include marble and hydrothermal deposits, with only rare occurrences in carbonatite and kimberlite igneous rocks.
Industry:Science
The liver X receptor (LXR) is a nuclear hormone receptor that is involved in the regulation of fatty acid and cholesterol metabolism. Nuclear hormone receptors constitute a family of specialized proteins in the nucleus that can switch on individual genes in response to the changing needs of the organism. These proteins contain two functional units: (1) a deoxyribonucleic acid (DNA)–binding domain that binds to target DNA sequences within the promoter region of genes that regulate many aspects of vertebrate metabolism and (2) a ligand-binding domain, to which hormones or other small molecules (ligands) attach. Binding of the ligand activates the receptor complex, displaces corepressor proteins from the promoters, and helps recruit coactivator proteins that link the receptor complex to the basic transcription machinery of the gene. This activates the production of multiple copies of its messenger RNA (mRNA) that, in turn, stimulate protein synthesis.
Industry:Science
The scientific analysis of biological evidence to provide objective information on legal matters or those that pertain to criminal and civil law. Biological evidence such as bodily fluids or tissues that may be found at crime scenes can be analyzed through deoxyribonucleic acid (DNA) typing. Typing requires detection and screening of the biological evidence, such as blood, semen, or saliva, extracting the DNA from a specimen, amplifying specific regions of the DNA using the polymerase chain reaction (PCR), and typing the resulting PCR products to determine a DNA profile. The DNA profile from the evidence is then compared to known profiles from suspects, victims, or database samples to determine the significance of the result. Samples containing mixtures require additional interpretation to infer individual donor allele designations. Forensic biologists must also assess the statistical significance of their results, write reports, and testify in court.
Industry:Science
The multidisciplinary study of industrial and economic systems and their linkages with fundamental natural systems. Industrial ecology incorporates research involving energy supplies, materials, technologies, and technological systems; physical, biological, and social sciences; economics; law; and business management. Industrial and economic systems are viewed not in isolation but in their cultural and ecological context. Both demand-side (consumer) and supply-side (producer) activities are included, as are all sectors of economic activity, such as mining, agriculture, forestry, fisheries, manufacturing, and service activities. Industrial ecology also includes subsistence activities at the fringes of formal economic systems, which generate a number of important impacts on natural systems. Industrial ecology provides the understanding to support the reasoned improvement of the economic, environmental, and social efficiency of current industrial systems.
Industry:Science
The portion, referred to as an eon, of geological time that extends for several hundred million years from the end of the accretion of the Earth to the formation of the oldest recognized rocks. According to current models, the inner planets formed by the accretion of planetesimals in an environment where gas and volatiles had been swept away by early intense solar activity. The accretion of the Earth appears to have been completed between 50 and 100 million years (m.y.) after the beginning of the solar system (<i>T</i><sub>0</sub>) as recorded in the oldest refractory inclusions in the Allende Meteorite, whose age of 4566 ± 2 m.y., ascertained by lead isotope dating, is taken as <i>T</i><sub>0</sub>. Core formation on the Earth appears to have been coeval with accretion and so preceded the Hadean. Any primitive atmosphere was removed by early collisional events, and the present atmosphere has arisen by a combination of degassing and additions from comets.
Industry:Science
The science of the electrical activity of the heart. The heartbeat results from the development and organized control of cardiac excitability, including ionic current flow across the cardiac membrane, within and between cells, and throughout the body, which in turn allows the orderly contraction of heart muscle and the efficient pumping of blood. Alterations in these determinants of normal cardiac excitability may lead to abnormalities in the rhythm of the heart (arrhythmias or dysrhythmias) and in the propagation of electrical impulses throughout the heart (conduction defects). Cellular electrophysiologic events lead to the establishment of extracellular potentials on the surface of the body. Electrocardiographic, vectorcardiographic, and other recording systems are used to determine the orientation and magnitude of that extracellular potential. The normal heart produces characteristic sequences of extracellular potentials that may be altered by disease.
Industry:Science
The sponges, a phylum of the animal kingdom that includes more than 8000 described species. The body plan of sponges is unique among animals. Currents of water are drawn through small pores, or ostia, in the sponge body and leave by way of larger openings called oscula. The beating of flagella on collar cells or choanocytes, localized in chambers on the interior of the sponge, maintains the water current. Support for the sponge tissues is provided by calcareous or siliceous spicules, by organic fibers, or by a combination of organic fibers and siliceous spicules. Some species have a compound skeleton of organic fibers, siliceous spicules, and a basal mass of aragonite or calcite. The skeletons of species with supporting networks of organic fibers have long been used for bathing and cleaning purposes. Because of their simple and possibly primitive organization, sponges are of interest to zoologists as an aid in understanding the origin of multicellular animals.
Industry:Science
The most abundant and widespread of the phosphate minerals, crystallizing in the hexagonal system, space group P6<sub>3</sub>/m. The apatite structure type includes no less than 10 mineral species and has the general formula X<sub>5</sub>(YO<sub>4</sub>)<sub>3</sub>Z, where X is usually Ca<sup>2+</sup> or Pb<sup>2+</sup> or As<sup>5+</sup>, and Z is F<sup>−</sup>, Cl<sup>−</sup>, or (OH)<sup>−</sup>. The apatite series takes X = Ca, whereas the pyromorphite series includes those members with X = Pb. Three end members form a complete solid-solution series involving the halide and hydroxyl anions and these are fluorapatite, Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>F; chlorapatite, Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>Cl; and hydroxyapatite, Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH). Thus, the general series can be written Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(F,Cl,OH), the fluoride member being the most frequent and often simply called apatite.
Industry:Science
The statistical description of atmospheric motions over the Earth, their role in transporting energy, and the transformations among different forms of energy. Through their influence on the pressure distributions that drive the winds, spatial variations of heating and cooling generate air circulations, but these are continually dissipated by friction. While large day-to-day and seasonal changes occur, the mean circulation during a given season tends to be much the same from year to year. Thus, in the long run and for the global atmosphere as a whole, the generation of motions nearly balances the dissipation. The same is true of the long-term balance between solar radiation absorbed and infrared radiation emitted by the Earth–atmosphere system, as evidenced by its relatively constant temperature. Both air and ocean currents, which are mainly driven by the winds, transport heat. Hence the atmospheric and oceanic general circulations form cooperative systems.
Industry:Science
