- 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.
Many elegant solutions to engineering problems have been inspired by biological phenomena. Robots have been modeled after insects and other organisms, and leaves have served as models for solar membrane folding. Biological models have also been used to develop novel materials, actuators, and sensors. However, it is not always clear how the particular biological models were identified or selected. For example, an engineer open to using biological models for design might not know how to find relevant biological analogies for a given design. Therefore, a general method was developed for which analogous biological phenomena can be identified and used on any design problem.
Industry:Science
Neutron scattering is a widely used technique for determining both the atomic and magnetic structures of materials and the way in which these structures evolve in time. It can provide remarkably precise and unique information about the structure and dynamics of a variety of materials that are often difficult to interrogate by other means. As scientific interest moves to increasingly complex structures and the goals of nanoscience are pursued, new and more powerful neutron sources currently coming on line will be able to contribute new insights, building on a tradition that started 60 years ago with experiments by scientists such as Clifford Shull and Bertram Brockhouse.
Industry:Science
One of the longstanding goals of modern cosmology has been to determine the global geometry of the universe. This is the geometry of the universe at very large scales (greater than about 2 × 10<sup>8</sup> light-years), at which the distribution of galaxies appears to be uniform. Determining the global geometry would answer the question of what is the curvature of space on the largest scales. (While the space-time of general relativity has four dimensions, it can be characterized by a curvature, just like a two-dimensional surface.) That is, is this space flat or curved? And, if curved, is the curvature positive (like a sphere) or negative (like a saddle-shaped surface)?
Industry:Science
In the scientific sense, a theory that expresses various reciprocal relations for the behavior of some physical systems. Reciprocity applies to a physical system whose input and output can be interchanged without altering the response of the system to a given excitation. Optical, acoustical, electrical, and mechanical devices that operate equally well in either direction are reciprocal systems, whereas unidirectional devices violate reciprocity. The theory of reciprocity facilitates the evaluation of the performance of a physical system. If a system must operate equally well in two directions, there is no need to consider any nonreciprocal components when designing it.
Industry:Science
Invasive species are organisms that have expanded their geographic ranges and become established in new habitats. Although species invasions have occurred throughout evolutionary history, human activities have greatly increased their frequency and scope, particularly in the last 200 years. Although only a fraction of species introductions result in established, invasive populations, successful invasions can cause profound negative changes in recipient ecosystems and the human societies dependent upon those ecosystems. Ecologists, economists, resource managers, and policymakers devote considerable energy to studying and minimizing the negative impacts of species invasions.
Industry:Science
Mountain glaciers are good indicators of global climate change. Glaciers are masses of ice found on land that are thick enough to flow under their own weight or that show evidence of past movement. Documenting the retreat of tropical glaciers is difficult because they are often located in remote areas with steep terrain and inclement weather. However, today's computerized mapping technologies, including remote sensing and geographic information systems (GIS), can complement field studies in tracking changes of these remote glaciers. In fact, the Intergovernmental Panel on Climate Change (IPCC) has recommended the use of satellite remote sensing to document glacier change.
Industry:Science
Marine refrigerating equipment is used for shipboard refrigeration of products as well as for air conditioning the quarters of passengers and crew. Shipboard refrigeration is necessary for the preservation of perishables in transit and foodstuffs to be used by passengers and crew. Marine refrigeration is also used for maintaining certain cargo products in liquid form that would otherwise evaporate when stored at ambient conditions. A Typical ship stores or cargo refrigeration plant consists of a compressor, motor, condensor, receiver, evaporators, and controls. A typical air-conditioning unit consists of a compressor, motor, condenser, receiver, water chiller, and controls.
Industry:Science
Regularly occurring, oriented seasonal movements of individuals of many animal species. The term migration is used to refer to a diversity of animal movements, ranging from short-distance dispersal and one-way migration to round-trip migrations occurring on time scales from hours (the vertical movements of aquatic plankton) to years (the return of salmon to their natal streams following several years and thousands of miles of travel in the open sea). This article will concentrate on seasonal movements, usually between breeding and nonbreeding areas, that have clear directionality and are long-distance relative to the sizes and locomotory abilities of the species involved.
Industry:Science
In its simplest form, quorum sensing refers to the ability of bacteria to communicate. It describes the capacity of certain bacteria to exhibit coordinated behavior in response to a particular population density. These bacteria usually rely on the production, accumulation, and subsequent response to diffusible signal molecules in order to sense population. These signal molecules accumulate in environments that can sustain a sufficiently dense population, or quorum, of the signal-producing bacteria. When the concentration of the signal molecule reaches a critical level, the quorum-sensing bacterial population responds through the concerted expression of specific target genes.
Industry:Science
Sorghum includes many widely cultivated grasses having a variety of names. Sorghum is known as guinea corn in West Africa, Kafir corn in South Africa, mtama in East Africa, and durra in the Sudan. In India sorghums are called juar, jowar, or cholam; in China, kaoliang; and in the United States, milo. Cultivated sorghums in the United States are classified as a single species, <i>Sorghum bicolor</i>, although there are many varieties and hybrids. The two major types of sorghum are the grain, or nonsaccharine, type, cultivated for grain production and to a lesser extent for forage, and the sweet, or saccharine, type, used for forage production and for making syrup and sugar.
Industry:Science
