- 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.
The terahertz (THz) region of the electromagnetic spectrum, broadly defined, comprises the range of frequencies from 100 GHz (10<sup>11</sup> Hz) to 10 THz (10<sup>13</sup> Hz), corresponding to free-space wavelengths from 3 mm to 30 micrometers. This radiation, sometimes called “T-rays,” bridges the frequency gap between microwaves and long-wavelength infrared waves, and historically was of interest primarily to astronomers probing the cosmic microwave background, and fusion physicists diagnosing plasmas. This difficult transition region between radio frequencies and optics has become much more accessible in recent years with the development of new sources and detectors, spawning tantalizing potential applications for terahertz imaging in areas as diverse as hazardous-materials detection and security, nondestructive testing, medical imaging, and astronomy. As is the case in other wavelength regions, imaging is the natural way to retrieve spatial information contained in a terahertz scene.
Industry:Science
The study of how the distributions and numbers of humans are determined by interactions with conspecific individuals, with members of other species, and with the abiotic environment. Human ecology encompasses both the responses of humans to, and the effects of humans on, the environment. The lineage leading to modern humans arose in Africa millions of years ago. The oldest fossil remains of members of the genus <i>Homo</i> are estimated to be about 2 million years old. The tools associated with human fossils, as well as cave paintings created by early humans, reveal the existence of culture. Cultural learning greatly facilitated the spread of domestic plants and animals and the development of pastoral and agricultural societies. Agriculture, in turn, led to an increasingly sedentary life, greatly expanded food supplies, the development of cities, and the rapid growth of the human population. Human ecology today is the combined result of humans' evolutionary nature and cultural developments.
Industry:Science
The successive subdivisions along the length of the body axis in bilaterally symmetrical animals; also called somites or segments. Common examples are the muscles and spinal nerves in the human body and in the body and tail of many mammals, snakes and lizards, salamanders, and fishes. It also occurs in other chordates, and in arthropods and annelid worms. It never involves reproductive organs, and thus differs from strobilization in tapeworms and certain jellyfish. This serial repetition of parts (metamerism or segmentation) arises either from a bilateral series of coelomic pouches which form the segmental muscles, kidneys, and body cavities of lower forms, or from mesoblastic somites which form the skeletal and muscular segments of vertebrates. Repetitive features of the nervous system are acquired secondarily through the influence of mesodermal metameres upon adjoining ectodermal tissues. Several primitive embryonic somites become fused in the heads of adult arthropods and vertebrates.
Industry:Science
The physical separation and removal of particles, either solid or liquid, from a gas in which they are suspended. Such separation is required for one or more of the following purposes: (1) to collect a product which has been processed or handled in gas suspension, as in spray-drying or pneumatic conveying; (2) to recover a valuable product inadvertently mixed with processing gases, as in kiln or smelter exhausts; (3) to eliminate a nuisance, as in fly-ash removal; (4) to reduce equipment maintenance, as in engine intake air filters; (5) to eliminate a health, fire, explosion, or safety hazard, as in bagging operations or nuclear separations plant ventilation air; and (6) to improve product quality, as in cleaning of air used in processing pharmaceutical or photographic products. Achievement of these objectives involves primarily gas-handling equipment, but the design must be concerned with the properties and relative amounts of the suspended particles as well as with those of the gas being handled.
Industry:Science
The purpose of the Gravity Probe B (GP-B) experiment is to test two effects predicted by the general theory of relativity. This theory, established in 1916 by Albert Einstein, provides a geometrical framework for gravity, one of the four known forces in the universe. This view of gravity uses a metric to describe the curvature of space and time. Far from massive bodies, this metric reduces to that for euclidean space. In 1960, Leonard I. Schiff, using the general theory of relativity, predicted two new relativistic effects which cause an orbiting gyroscope to slowly precess. The first effect, known as the geodetic effect, is caused by the orbital motion of a gyroscope about the static mass of the Earth. The second effect, known as the frame dragging or gravitomagnetic effect, is caused by the rotation of the massive Earth. Frame dragging causes a slow rotation of the Earth's local space-time framework. The Gravity Probe B experiment will measure the size of these two deviations from flat space-time.
Industry:Science
The replacement of paper-based medical documentation by electronic documentation dates back to the early use of computers in the 1960s. Since then, electronic medical records (EMRs) have become more complex, and both the content and the functionality have increased substantially and will increase further in the near future. The implementation of an EMR is a long-term project and is related to a transformation process for the health-care system. Today's health-care systems are fragmented, not very efficient and ineffective, and with safety shortcomings. The development of an efficient information and communication technology (ICT) infrastructure for documentation, archiving, retrieval, communication, and processing of health-related data provides a great opportunity for improving health care and social systems worldwide. Therefore, a shift from provider-oriented documentation to patient-centered communication and integrated health care is essential. This could be achieved by the implementation of EMRs.
Industry:Science
The study of animal behavior. Modern ethology includes many different approaches, but the original emphasis, as expounded by Konrad Lorenz and Niko Tinbergen, was placed on the natural behavior of animals. This contrasted with the focus of comparative psychologists on behavior in artificial laboratory situations such as mazes and puzzle boxes. Ethologists view the naturalistic approach as crucial because it reveals the environmental and social circumstances in which the behavior originally evolved, and prepares the way for more realistically designed laboratory experiments. The approach goes back to the stress that Charles Darwin placed on hereditary contributions to behavior in all species, including humans. Viewing behavior as a product of evolutionary history has helped to elucidate many otherwise puzzling aspects of its biology and has paved the way for the new science of neuroethology, concerned with how the structure and functioning of the brain controls behavior and makes learning possible.
Industry:Science
The study of the functional properties of insect tissues and organs. Insects are one of the most diverse groups of animals on Earth. They have evolved adaptations that allow them to live in a variety of ecosystems. The basic body plan comprises a hard exoskeleton forming a protective covering over internal tissues. The interior of the exoskeleton is referred to as the hemocoel. Insects have an open circulatory system with hemolymph (blood) freely moving within the hemocoel and bathing all of the internal tissues. A basement membrane composed of a noncellular matrix of proteins, lipids, and carbohydrates separates the internal tissues from the hemolymph. The fat body is a specialized tissue within the hemocoel. It is usually a whitish tissue found throughout the body of the insect and is involved in storing fat reserves. It is also involved in general metabolism and regulates the composition of the hemolymph. The fat body is, in fact, the site of production for the major proteins found in the hemolymph.
Industry:Science
The probability that social or economic consequences of earthquakes will equal or exceed specified values at a site, at several sites, or in an area, during a specified exposure time. Historically the term seismic risk has been used to describe an assortment of earthquake effects that range from ground shaking, surface faulting, and earthquake-induced landsliding to economic loss and casualties. As more quantitative methods for estimating the effects of earthquakes have been developed, terminology has become more precise. Although the term seismic risk is still sometimes used in a general sense to mean the potential for both the occurrence of natural phenomena and the economic and life loss associated with earthquakes, it is useful to differentiate between the concepts of seismic hazard and seismic risk. Seismic hazard may be defined as any physical phenomena (for example, ground shaking or ground failure) that are associated with an earthquake and that may produce adverse effects on human activities.
Industry:Science
The supply of heat, either in the form of steam or hot water, from a central source to a group of buildings. As an industry, district heating began in the early 1900s with distribution of exhaust steam, previously wasted to the atmosphere, from power plants located close to business and industrial districts. Advent of condensing-type electrical generating plants and development of long-distance electrical transmission led to concentration of electrical generation in large plants remote from business districts. Most district heating systems in the United States rely on separate steam generation facilities close to load centers. In some cities, notably New York, high-pressure district steam (over 120 lb/in.<sup>2</sup> or 830 kilopascals) is used extensively to feed turbines that drive pumps and refrigerant compressors. Although some district heating plants serve detached residences, the cost of underground piping and the small quantities of heating service required make this service generally unfeasible.
Industry:Science
