- 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.
Camouflage techniques have been employed by both humans and animals trying to become invisible to their predators or to their prey. Human fascination with invisibility can be traced from ancient times to modern literature. Materials that have the property of making objects or bodies invisible to the eye or undetectable by the ears or other sensing devices have been a dream of military engineers and scientists for centuries. While camouflage has been the solution adopted to achieve optical invisibility, for acoustic invisibility the reduction of noise generated when the object or body moves was formerly the more feasible solution.
Industry:Science
Detecting and discriminating various chemicals in the environment is critical for the survival of most animals on this planet. They depend on their sense of smell (olfaction) to locate food, mates, and predators. For a compound to be smelled by air-breathing animals, it needs to be volatile or semivolatile. In general, odors are nonionic, hydrophobic, organic molecules with molecular weights of no more than 350 daltons. The odor quality of a molecule is largely determined by its size, shape, and functional groups. Mammals are able to distinguish among thousands of odors, and this amazing task is performed by the olfactory system.
Industry:Science
Fungi that live in the interior of plant host tissues without causing external symptoms. The term endophyte literally means “living within” and is contrasted with epiphyte, which means “living on the surface.” These descriptive terms are used in several disciplines such as microbiology, mycology, and ecology, and at times their use is controversial. This article uses the term endophyte in a broad and topographical sense following the definition of O. Petrini (1991): “endophytes colonize asymptomatically the living, internal tissues of their hosts, even though the endophyte may after an incubation or latency period cause disease.”
Industry:Science
Human activity has caused subtle changes in the Earth's atmosphere over the past several decades due to increased emissions of gases such as carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>). These anthropogenic changes in greenhouse gases have the potential for increasing the temperature in the lower atmosphere due to their ability to absorb infrared radiation. The far-reaching consequences of these changes are now being seen at extremely high altitudes in the outer atmosphere of the Earth, especially in the thermosphere, the high-temperature, near-vacuum region ~90–500 km, which is where many satellites are in orbit.
Industry:Science
Exploration for mineral deposits by chemically analyzing sampled rock, soil, vegetation, and other natural materials for trace amounts of the principal and associated elements. By now, most of the easily discovered mineral deposits have been found, making the search for new deposits ever more challenging. In spite of this, worldwide demands are rising for energy, metallic, and nonmetallic mineral resources. Search continues in regions of known mineralization and in areas where deposits are covered by sediment or obscured by vegetation and ice. Geochemical techniques have become an important part of almost all exploration programs.
Industry:Science
Flow in which the Reynolds number is very small. Fluid dynamics encompasses an intriguing array of phenomenologically rich processes, from weather prediction in the atmosphere to the swimming of the tiniest microorganism in its natural environment. A qualitative measure of the expected behavior in a given fluid dynamics system is found from the Reynolds number, Re = density · length · velocity/viscosity. In the case where Re is very small (much less than 1, usually), the inertia effects (momentum, acceleration, and body forces) become negligible in comparison to the viscous resistance. This situation is described as creeping flow.
Industry:Science
Any of approximately 20 species of deciduous tree fruits in the genus <i>Pyrus</i>. About half of the species are native to Europe, North Africa, and the Middle East around the Mediterranean Sea; the others are native to Asia. Pear culture is documented to have started as early as 1100 <small>B.C.</small> Pears are best adapted to temperate climates with warm, dry summers and cold winters. They require winter cold to break the dormant period but are injured by temperatures below −10 to −15°F (−23 to −26°C). Commercial pear production in the United States is concentrated in the interior valleys of California, Oregon, and Washington.
Industry:Science
Any tree of the genus <i>Pinus</i>, of the family Pinaceae, characterized by evergreen leaves, usually in tight clusters (fascicles) of two to five, rarely single. There are about 80 known species of pine distributed throughout the Northern Hemisphere. Botanically, the leaves are of two kinds: (1) a scalelike form, the primary leaf, subtending a much shortened and eventually deciduous shoot, which bears (2) the secondary leaves or needles. The wood of pines is recognized easily by the numerous resin ducts and the characteristic resinous odor. The pines may be divided into two classes, according to the number of leaves in a cluster.
Industry:Science
Direct absorption spectroscopy is the ideal method for measuring concentration and chemical composition in a variety of environments. However, it generally requires a very stable light source, such that continuous-wave lasers must be used to achieve high sensitivity. This is unfortunate because pulsed lasers cover a larger portion of the spectrum and are considerably easier to use. The development of cavity ringdown laser absorption spectroscopy (CRLAS) has allowed researchers to use simple pulsed laser technology in direct absorption experiments, achieving sensitivities rivaling that of more complicated continuous-wave techniques.
Industry:Science
In a general sense, the science of the application of lighting. Radiation in the range of wavelengths of 0.38–0.76 micrometer produces the visual effect commonly called light by the response of the average human eye for normal (photopic) brilliance levels. Illumination engineering pertains to the sources of lighting and the design of lighting systems which distribute light to produce a comfortable and effective environment for seeing. In a specific quantitative sense, illumination is the combination of the spatial density of radiant power received at a surface and the effectiveness of that radiation in producing a visual effect.
Industry:Science
