- 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.
Chemical techniques are applied in archeological research to determine the composition and isotopic makeup of biological, natural, and synthetic remains. Chemical and isotopic studies of plant and animal residues are undertaken to investigate ancient diet, nutrition, and resource use. Compositional analysis of natural or synthetic materials and residues is performed to ascertain artifact manufacturing processes and use. Archeological chemistry expertise is used to ascertain the processes that govern the preservation and decay of materials, thus providing valuable information regarding subsequent conservation and restoration. It has also been employed to determine the location of a geographical source of procurement or production of materials used in long-distance contact or trade.
Industry:Science
Devices that perform functions in the superconducting state that would be difficult or impossible to perform at room temperature, or that contain components which perform such functions. The superconducting state involves a loss of electrical resistance and occurs in many metals and alloys at temperatures near absolute zero. An enormous impetus was provided by the discovery in 1986 of a new class of ceramic, high-transition-temperature (<i>T<sub>c</sub></i>) superconductors, which has resulted in a new superconducting technology at liquid nitrogen temperature. Superconducting devices may be conveniently divided into two categories: small-scale thin-film devices, and large-scale devices which employ zero-resistance superconducting windings made of type II superconducting materials.
Industry:Science
Fluorescence microscopy is one of the most powerful and widely used imaging techniques in biological research because it can visualize dynamic processes inside living cells with exquisite sensitivity and specificity. Major breakthroughs have included the development of confocal microscopy in the 1980s and two-photon microscopy in the 1990s. These advances have been accompanied by groundbreaking improvements in the ability to visualize specific proteins and organelles inside living cells using fluorescent proteins (for example, green fluorescent protein (GFP)) and transgenic technology. In addition, tremendous increases in computing power have enabled the acquisition and analysis of large imaging data sets and thus have further facilitated the ascendancy of fluorescence microscopy.
Industry:Science
Impulsive stimulated thermal scattering, also known as transient grating photoacoustics, is a purely optical, noncontacting method capable of characterizing the high-frequency acoustic behavior of surfaces, thin membranes, coatings, and multilayer assemblies. It has emerged as a generally useful analytical technique for thin-film materials research. Recent advances in experimental design have improved and simplified the ISTS measurement dramatically, resulting in straightforward, inexpensive setups and even a commercial ISTS instrument that requires no user adjustments of lasers or optics. This tool is now used routinely in the microelectronics industry for rapid (~1 s) and nondestructive measurements of metal film thickness with atomic-level precision and high spatial resolution.
Industry:Science
Critically important to ecology, evolutionary biology, and paleobiology is the problem of scale, that is, the idea that spatial and temporal scales of observation determine the patterns that emerge from the data. The number of trilobite species in a particular Paleozoic deposit, for example, may fluctuate in a directionless manner over short geological intervals, belying a long-term, global diversity trend. If the apparently random fluctuations observed on small spatiotemporal scales are mere noise within larger-scale, deterministic patterns, data cannot be scaled up from real-time ecological observations to predict patterns in the fossil record. If, however, at least some patterns and processes are scale independent, ecology has the potential to predict macroevolutionary dynamics.
Industry:Science
Diarrhea and its complications are the most important causes of infant death in most developing regions. The causes of the illness vary from dietary incompatibilities to intestinal infection. The most important infectious causes are, in approximate order of importance, rotavirus, the bacteria <i>Campylobacter jejuni</i>, <i>Shigella</i> (often causing dysentery or passage of bloody stools), <i>Salmonella</i>, and <i>Escherichia coli</i>, and the parasites <i>Giardia lamblia</i>, <i>Cryptosporidium</i>, and <i>Entamoeba histolytica</i>. The microorganisms are spread to the infant from other persons or through food or water. Breast-feeding is associated with a decreased occurrence of diarrhea and represents a major means of preventing infantile diarrhea in the developing world.
Industry:Science
As integrated circuits have become more complex, testing them has become more challenging. Tests are required in three situations. The earliest test is applied at the wafer stage of fabrication to ascertain that the manufacturing process has succeeded and that packaging of the individual integrated circuits, one of the most expensive stages of manufacture, is worthwhile. The second phase is when the integrated circuit has been incorporated into an electronic product. This test, which is often applied at the board stage, when the printed-circuit card is tested, also checks for faults in the board and in its assembly. The final test situation is when the circuit is in operation, to check whether a fault has occurred and to indicate to the user that the system is functioning correctly.
Industry:Science
Conditions in which two or more phases of fused-salt mixtures can coexist in thermodynamic equilibrium. Phase diagrams of these equilibrium conditions summarize basic knowledge about fused salts. Numerous advances in the technologies which are based on high-temperature chemistry have become possible through the increase in knowledge about fused salts. The increasingly significant role of fused salts in industrial processes is evident in the widening application of these materials as heat-transfer media, in extractive metallurgy, in nonaqueous reprocessing of nuclear reactor fuels, and in the development of nuclear reactors which create more fuel than they consume (breeder reactors); moreover, these technologies are all direct outgrowths of research and development with fused salts.
Industry:Science
Ever since the invention of the microscope, one of the great trends of modern science has been toward resolving ever-finer detail in the study of matter. Since small objects generally move quickly (which simply follows from the dependence of inertia on mass), high spatial resolution alone is not sufficient to image such objects (for example, to take a magnified photograph of them with a camera). A short-duration flash of light (or fast shutter) is also necessary to prevent blurring of the image. While the millisecond duration of an ordinary camera is sufficient to freeze the action of a person running (meter-scale length), a strobe light with ultrashort pulse duration (1 femtosecond or 10<sup>−15</sup> s) is required in order to resolve a moving atom (10<sup>−10</sup>-m-scale length).
Industry:Science
Correlations between acoustical features of sound (for example, the frequency of a pure tone) and physiological activity in the brain (for example, the number and timing of electrical pulses fired by a neuron) are being investigated with scientific methods that incorporate recent technological advances in the processing of bioelectric, biomagnetic, and biochemical signals. On the rich foundation of basic knowledge accrued since the 1950s about how the brain and ear process acoustical features of simple synthetic stimuli such as pure tones, scientists are analyzing the relationship of acoustical–physiological correlates to perceptual attributes of sounds (for example, the pitch of one's voice). This effort has been accelerated in recent years by rapid developments in human brain imaging.
Industry:Science
