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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.
Alternating current (ac) power generators produce sinusoidal voltage waveforms. Transmission through powerlines and transformers has little effect on the shape of the voltage. Electronic loads, however, produce distortions in the waveform. The amount of voltage distortion is a function of the amount of current and the impedance of the delivery system. Electronic equipment generally controls the current drawn by starting or stopping the current flow within each voltage cycle. The result is a nonlinear current draw and a distorted current flow. Thus, the introduction of modern electronic systems has required changes in the designs of private and utility electric power systems. Commercial buildings and industrial facilities are likely to contain equipment that distorts the voltage of the electricity supply. Modern designers try to restrict that effect to the smallest possible portion of the system.
Industry:Science
Although aboveground herbivores are known to affect plant community structure and function, the role of belowground herbivores in plant ecology is not well understood. Conducting research on belowground herbivores is difficult, primarily because of the dense, opaque nature of the soil medium that impedes direct observation belowground. Root herbivory is likely to have an important influence on plant communities because 50–90% of new plant growth is allocated belowground, and the loss of belowground biomass has greater impacts on plants than an equivalent loss of leaves or stems. Belowground herbivores affect plants through both their direct consumption and their indirect effects on decomposer and plant communities.
Industry:Science
Although dinosaurs are clearly reptiles, there has been a tendency in recent years to recast their biology and physiology as birdlike or mammallike. The scientific case for warm-blooded dinosaurs was presented in a series of publications beginning in 1971. In 1974, there were proposals for the scientific community to recognize the Dinosauria (including dinosaur descendants, the birds) as a class separate from the reptiles from which they were derived. This has led to confusion in popular literature as to whether or not dinosaurs were actually reptiles.
Industry:Science
Although long called a continent, in many physical ways Europe is but a great western peninsula of the Eurasian landmass. Its eastern limits are arbitrary and are conventionally drawn along the water divide of the Ural Mountains, the Ural River, the Caspian Sea, and the Caucasus watershed to the Black Sea. On all other sides Europe is surrounded by salt water. The stretches of water between the Mediterranean and Black seas, however, are narrow, and it is possible to swim across the Bosporus to Asia Minor. Not even the Mediterranean Sea is a real physiographic boundary inasmuch as the Atlas Mountains of northwestern Africa are structurally part of the great Tethys geosyncline. Of the oceanic islands of Franz Josef Land, Spitsbergen (Svalbard), Iceland, and the Azores, only Iceland is regarded, mainly on historical grounds, as an integral part of Europe; thus the northwestern boundary is drawn along the Danish Strait.
Industry:Science
Although normally thought of as a feature of mountainous regions, landslides can happen almost any place where the ground surface slopes. In fact, some of the largest landslides on Earth occur under water. Suboceanic or submarine landslides can involve the movement of rocks and sediments entirely beneath the sea, or they can begin as partly above-water landslides that later enter the ocean. Like open-air landslides, submarine landslides often strike steep inclines (~10°). Unlike open-air slides, submarine landslides also occur in very slightly dipping terrain (<1°). Many historical and prehistorical landslides have raked the slopes of deep ocean trenches and continental margins where strong earthquakes recur periodically. Seismic shaking probably triggered these slides. Other landslides, however, have been located on seismically quiet continental margins, such as the east and west edges of the Atlantic Ocean, and on the flanks of oceanic island volcanoes in Hawaii and the Canary Islands. Best evidence suggests that the potential for suboceanic landslides exists globally, whether in tectonically active or tectonically inactive regions. A primary hazard of submarine landslides, like their land-bound relatives, is the wasting of human-made structures along their path. The newest research, however, perceives that undersea slope failures present an additional threat—landslide-generated tsunami waves.
Industry:Science
Although not essential to life or health, the gallbladder is the site and source of appreciable suffering and disease in humans. With its cystic duct, the gallbladder constitutes a blind-ended, lateral extension of the common bile duct. It is roughly the size and shape of a small pear, and is adherent to the outer surface of the liver. Besides acting as a reservoir for bile, the gallbladder concentrates and otherwise alters the composition of bile.
Industry:Science
Although not generally recognized, parasitic organisms make up a large percentage of the Earth's total biodiversity. The word “parasite” generally conjures up images of organisms such as microbes and worms, but this life-form has evolved repeatedly in many groups, including flowering plants (angiosperms). A parasitic angiosperm is one that attaches to a host root or stem via a modified root called the haustorium, thereby deriving some or all of its water and nutrients. Some parasitic plants are green and photosynthetic, but they still obtain water and solutes from their host. These are called hemiparasites (somewhat of a misnomer in that they are fully parasitic). Other parasitic plants have lost their ability to conduct photosynthesis and are thus fully heterotrophic (that is, obtaining nourishment from exogenous organic matter). These are called holoparasites, and they obtain carbohydrates from host phloem as well as water from the host xylem. Here a plant is considered parasitic only if it forms a direct haustorial connection to a host plant. This excludes plants such as Indian pipe (<i>Monotropa</i>) that attach to mycorrhizal fungi and are technically known as mycoheterotrophs.
Industry:Science
Although optical fiber technology is usually considered to be an excellent example of human innovation and engineering, recent investigations have revealed that silica fibers capable of guiding light are manufactured as well by a simple deep-sea sponge. Indeed, several other “primitive” organisms have already been shown to exhibit sophisticated solutions to complex optical problems. The skeleton of the “Venus's flower basket” (<i>Euplectella aspergillum</i>), a hexactenellid sponge that lives at ocean depths ranging from 35 to 5000 m (115 to 16,400 ft), contains silicious spicules (spiny fibers) exhibiting optical and mechanical properties that are comparable, and in some cases superior, to manmade optical fibers. As such, these spicules may serve the sponge as a fiber optic network for the collection or the distribution of light. A better understanding of these natural silica fibers may lead to improvements in the design, fabrication, and performance of commercial optical fibers.
Industry:Science
Although plants and animals deploy a complex array of defense responses to ward off invading microorganisms, the nature of their responses is different. Plant defense against microbes can be ascribed to a combination of constitutive (preexisting) and induced (postinfectional) mechanisms. Examples of constitutive resistance include physical barriers, such as the cuticle layer, and chemical barriers, such as antimicrobial phenolic compounds in plant leaves.
Industry:Science
Although probability theory derives its notion and terminology from intuition, a vague statement such as “John will probably come” is as remote from it as the statement “John is forceful and energetic” is remote from mechanics. Probability theory constructs abstract models, mostly of a qualitative nature, and only experience can show whether these reasonably describe laws of nature or life. As always in mathematics, only logical relations and implications enter the theory, and the notion of probability is just as undefinable (and as intuitive) as are the notions of point, line, or mass. An actual assignment of numerical probabilities is frequently unnecessary or impossible. For example, telephone exchanges are based on a theoretical comparison of several possible systems; only the optimal ones are built and the others discarded. Thus a huge industry depends on theoretical models of exchanges which will never exist.
Industry:Science
