- 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.
Micro-electro-mechanical systems (MEMS) is a term originally coined in the United States in the 1980s. In Europe the term microsystems technology (MST) is more usual, whereas in Japan the term micromachines is more widespread. These terms all refer to the same technology that is a by-product of the enormously successful semiconductor-microelectronics chip manufacturing industry. In this article the term MEMS will be deployed more generically, as it may be viewed as being a more accurate description of the science and technology underlying these miniature devices whose dimensions are measured in micrometers.
Industry:Science
Skeletal muscle is the most voluminous tissue in humans. There are about 670 different muscles in the human body, including 170 distinct skeletal muscles in the head. The skeletal musculature serves crucial functions in vertebrates. The body muscles, including trunk and limb muscles, are responsible for posture and locomotion, whereas the head muscles control the eyes, cranial openings, food uptake (mastication), and speech. Skeletal muscle displays the ability to regenerate after injury or in degenerative diseases. However, this regenerative capacity is exhausted over time and in severe muscle dystrophies.
Industry:Science
Metabolic engineering is the directed improvement of cellular properties or products by modifying specific biochemical reactions or introducing new ones using recombinant DNA technology. It is a subset of biochemical engineering, which has industrial and medical applications. Metabolic engineering is used by biotechnology, pharmaceutical, chemical, energy, and food companies to design or optimize microorganisms that overproduce particular chemicals. Products via metabolic engineering include drugs, enzymes, food, commodity chemicals, and fuels. Metabolic engineering has also been used to study human diseases.
Industry:Science
Phytoremediation is the use of plants to clean up environmental contamination of surface soils. It is more cost-effective and environmentally appealing than other currently available methods for soil detoxification. The most common approach for soil cleanup involves the excavation and removal of polluted soil to a chemical treatment facility or a long-term storage landfill facility. This method is very costly for large-scale decontamination and can be destructive to the environment. Phytoremediation, on the other hand, costs significantly less and does not require the same degree of environmental perturbation.
Industry:Science
Naturally occurring solids, formed by geological processes, that contain the rare-earth elements—the lanthanides (atomic numbers 57–71) and yttrium (atomic number 39)—as essential constituents. In a rare-earth mineral, at least one crystallographic site contains a total atomic ratio of lanthanides and yttrium that is greater than that of any other element. The mineral name generally has a suffix, called a Levinson modifier, indicating the dominant rare-earth element; for example, monazite-(La) (LaPO<sub>4</sub>) contains predominantly lanthanum, and monazite-(Ce) (CePO<sub>4</sub>) contains predominantly cerium.
Industry:Science
P-bodies, or processing bodies, are discrete cytoplasmic foci (chief centers of a morbid process) composed of messenger ribonucleic acid--protein complexes containing a subset of proteins involved in mRNA decay. Concentrated foci of mRNA decay enzymes were initially reported in mammalian cells and subsequently were further expanded in the yeast <i>Saccharomyces cerevisiae</i>. Recent studies indicate that P-bodies serve a dual functional role. In addition to mRNA decay, P-bodies are sites of mRNA storage for translationally silenced mRNAs, including noncoding microRNA-mediated translational silencing in mammals.
Industry:Science
Polymers, macromolecules, high polymers, and giant molecules are high-molecular-weight materials composed of repeating subunits. These materials may be organic, inorganic, or organometallic, and synthetic or natural in origin. Polymers are essential materials for almost every industry as adhesives, building materials, paper, cloths, fibers, coatings, plastics, ceramics, concretes, liquid crystals, photoresists, and coatings. They are also major components in soils and plant and animal life. They are important in nutrition, engineering, biology, medicine, computers, space exploration, health, and the environment.
Industry:Science
Recent advances in high-speed computing have benefited the field of computational fluid dynamics. Ship designers can now analyze by computer complex water- and air-flow behavior, previously poorly understood through expensive and time-consuming testing with scaled ship models. These improved computational fluid dynamics techniques are revolutionizing the ship design process and enabling better designs to be produced more quickly. This article provides an overview of the use of computational fluid dynamics in ship design; and then its use, along with theory and experiment, in design of sailing vessels for racing.
Industry:Science
In its simplest form, a vector is a directed line segment. Physical quantities, such as velocity, acceleration, force, and displacement, are vector quantities, or simply vectors, because they can be represented by directed line segments. The algebra of vectors was initiated principally through the works of W. R. Hamilton and H. G. Grassmann in the middle of the nineteenth century, and brought to the form presented here by the efforts of O. Heaviside and J. W. Gibbs in the late nineteenth century. Vector analysis is a tool of the mathematical physicist, because many physical laws can be expressed in vector form.
Industry:Science
Methods of fertility control, including contraception, that are intended to prevent pregnancy, and means of interrupting early pregnancy. The efficacy of the various methods and consistency of use vary widely. Factors associated with degree of effectiveness include user age, income, marital status, and intention (that is, whether contraception is used to delay or to prevent pregnancy). The available methods consist of hormonal methods (including oral contraceptives, subdermal implants, and injectable formulations), sterilization, intrauterine devices, barrier and chemical methods, and fertility awareness methods.
Industry:Science
