- 行业: Printing & publishing
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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.
Most simply, the art of directing the great sources of power in nature for the use and the convenience of humans. In its modern form engineering involves people, money, materials, machines, and energy. It is differentiated from science because it is primarily concerned with how to direct to useful and economical ends the natural phenomena which scientists discover and formulate into acceptable theories. Engineering therefore requires above all the creative imagination to innovate useful applications of natural phenomena. It is always dissatisfied with present methods and equipment. It seeks newer, cheaper, better means of using natural sources of energy and materials to improve the standard of living and to diminish toil.
Industry:Science
Polyelectrolytes are charged, usually water-soluble polymers which may be handled and processed at ambient conditions using materials of very low toxicity. It has been known for many years that solutions of oppositely charged polymers form complexes through multiple electrostatic interactions. Although many applications have been proposed for these complexes, few have been realized since the complexes are intractable once formed. A technique for producing polyelectrolyte complexes as uniform ultrathin films, some with internal structuring, was described in the early 1990s. Since then, numerous morphologies, compositions, and applications derived from complexed multicomposite (many different materials) films have been explored.
Industry:Science
Pedestrian protection has been overlooked for a long time, as motor vehicles have been favored over other road users. Vehicle safety was synonymous with occupant protection, and separating pedestrians from vehicle traffic was the only approach to protect vulnerable road users. However, the situation has changed, and pedestrian protection has gained more importance because of legislative and consumer testing requirements. The car occupant often is the custumer, and in most cases does not consider the role of a vulnerable road user when buying a car. Based on these considerations, including the relevance of pedestrians in accidents, the focus on pedestrian protection for passenger vehicles is clearly driven by public authorities.
Industry:Science
One of the categories into which stars may be classified, based on their place in the evolution of the galaxy that they occupy. The stellar component of the Milky Way Galaxy consists of three populations: the thin disk, the thick disk, and the halo. The thin disk, originally referred to as population I, is the youngest, located amid most of the molecular and cold atomic gas, and confined to a height of order 1 kiloparsec (3.3 × 10<sup>3</sup> light-years or 3.1 × 10<sup>16</sup> km or 1.9 × 10<sup>16</sup> mi) from the plane. The bulge and halo, roughly corresponding to the original population II, is a much older, far more extended structure, having an approximately spherical distribution with a scale length of order 3.5 kpc.
Industry:Science
New varieties of foods and food substances are being produced through modern biotechnological methods (for example, genetic engineering or recombinant DNA methods), whereby scientists introduce one or a few copies of genes into organisms used as sources of food to improve processing, nutritional, or agronomic characteristics. These new methods permit more precise, directed improvements than can be achieved through conventional methods that rely on the random processes of mutagenesis or mating between closely related organisms. Because the genes can be obtained from any organism (plant, animal, or microbe), questions have been raised about the safety and proper labeling of foods and food substances developed by modern biotechnology.
Industry:Science
Materials that serve above about 1000°F (540°C). In the broad sense, high-temperature materials can be identified by the following classes of construction solids: stainless steel (limited), austenitic superalloys, refractory metals, ceramics and ceramic composites, metal-matrix composites, and graphitic composites. The first three classes are well proven in industrial use, although stainless steels serve but slightly above 1000°F (540°C) and refractory metals are usually limited to nonoxidizing atmospheric conditions. The other classes are under extensive worldwide research to establish whether they can be utilized to replace and extend the capabilities of austenitic superalloys, which are the mainstay of high-temperature service.
Industry:Science
It is generally recognized that the impact of a 6-to-10-km-diameter (4-to-6-mi) asteroid 65 million years ago contributed significantly to the extinction of the dinosaurs and many other species living at the time. Fortunately, these types of events are very rare, but there is growing recognition that impacts of smaller objects can cause significant regional disasters and that these events can happen relatively frequently. Humanity may now have the technology to divert these smaller objects, but we need to know where they are and to decide how and when to take action. This article overviews the nature of the threat, describes options for deflecting a threatening object, and discusses uncertainties that will affect the decision to act.
Industry:Science
Physiological ecology combines the study of physiological processes, the functions of living organisms and their parts, with ecological processes that connect the individual organism with population dynamics and community structure. In the past, physiological ecology focused principally on physiological processes in isolation from each other and without strong quantitative connections to ecological processes. That focus is now rapidly changing into a dynamic quantitative and more integrated discipline. Physiological ecology reaches up to population dynamics and community structure and down to genetic phenomena influencing key endocrine functions affecting behavior, energetics, survival, reproduction, and fitness in diverse environments.
Industry:Science
Proteins are heteropolymers built from the 20 naturally occurring amino acids. These molecules, which may contain fewer than 50 or as many as several hundred amino acids, adopt unique three-dimensional structures (folds) determined by the sequence of amino acids in the polymeric chain. In the late 1960s, C. Levinthal formulated the paradox that an impossibly long period of time is required to fold an average-sized protein by a random search of all possible conformations. The fact that proteins fold quite rapidly demonstrates that they follow folding pathways to reach to their equilibrium conformations. Understanding how proteins form their unique structures from nonnative conformations remains a challenge for both theory and experiment.
Industry:Science
On May 2, 1863, while returning from a scouting mission during the Battle of Chancellorsville, Virginia, Confederate General Thomas J. “Stonewall” Jackson was fired upon and wounded. Dr. Hunter McGuire removed a spherical ball 0.675 in. in diameter from Jackson's right hand and amputated his left arm. Although he survived the wounding, he developed pneumonia and died on September 10, 1863. Because the Union Army had abandoned the use of the smooth-bore musket that fired this type of ammunition the previous year, investigators were able to conclude that Jackson had been shot by his own troops, who were still using that firearm. Many believe this to be the first recorded instance of the use of firearms identification for forensic purposes.
Industry:Science
