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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.
Florigen is a hypothetical stimulus that controls when a plant will flower in response to the changes in day length associated with the different seasons. Flowering occurs when shoot apical meristems—small regions of prolific cell division in the buds of the main shoot and lateral branches—stop producing vegetative tissues (stems and leaves) and instead produce floral tissues (a process called evocation). The transition to flowering is fundamental to the production of offspring and the survival of the species, and must be coordinated with seasonal change to (1) synchronize flowering within the species to promote cross-pollination, (2) harmonize flowering with the life cycles and behaviors of pollinators such as insects, and (3) coordinate flowering with the seasons to ensure that progeny (seeds) are sufficiently mature to survive unfavorable conditions, such as winter or hot, dry summers. The timing of this transition is also a concern for agriculture since seeds and fruits must be harvested within the growing season of the region.
Industry:Science
Historically, drug delivery technologies have been used to extend the duration of effect, or to speed the onset of action, of drugs or to improve the convenience of their administration. Today the role of drug delivery technology has been expanded to include improving the efficiency and specificity with which drugs can be delivered to their target organs or systems. Inhalational drug therapy, in which drugs are delivered to the lungs in the form of an aerosol, is one example. Because inhaled drugs are absorbed directly into the bloodstream, the development of pulmonary methods of drug delivery to replace oral methods avoids exposure of the drug to the harsh gastrointestinal environment, minimizing gastroin-testinal problems such as low solubility, low permeability, drug irritability, unwanted metabolites, and dosing uncertainty caused by meals of varied composition. Because they are delivered directly to diseased lungs, certain inhalable antibiotics may be more effective than oral or injectable antibiotics for treating lung infections.
Industry:Science
Beams of radioactive (unstable) nuclei. In several nuclear physics laboratories, a capability exists to produce such beams and, before these nuclei spontaneously decay, use them to gain insight into the reactions on and structure of nuclei never before accessible. Radioactive beams are particularly useful to study stellar explosions such as novae, supernovae, and x-ray bursts. These explosions are some of the most catastrophic events in the universe, generating enormous amounts of energy while synthesizing the elements that make up lifeforms and the world. These spectacular explosions involve, and in some cases are driven by, reactions where the atomic nuclei of hydrogen (protons) and helium (alpha particles) fuse with (are captured by) radioactive isotopes of heavier elements to form new elements. The capability to produce beams of radioactive nuclei allows direct measurements of these reactions, providing crucial information needed to theoretically model cataclysmic stellar events and to understand the origin of many chemical elements.
Industry:Science
Climate has shaped the course of history. Subtle variability in climate often dictates when there is famine and when there is plentitude. This is conveyed most strongly when normal patterns suddenly change. In Peru, for example, farmers have historically recognized <i>años</i> <i>de abundancia</i> (years of abundance) every 2 to 7 years. Unusually warm temperatures are accompanied by heavy rains, turning the coastal desert to abundant pasture. Crops and livestock thrive in regions where they typically languish. However, the sea, usually teeming with fish, becomes anomalously warm and dormant. This phenomenon, called El Niño (Little Boy or Christ Child) by Peruvians for its tendency to begin around Christmas, is now recognized as a disruption of the ocean-atmosphere system in the tropical waters of the Pacific with consequences felt around the globe. El Niño has received widespread attention because the interplay between winds and ocean currents affects not only the climate but also fisheries, marine biology, and, ultimately, human welfare.
Industry:Science
Contaminants can migrate through ground water from leaking underground storage tanks, landfills, and tailings ponds to wells or surface water bodies. Cleanup usually includes the removal of sources of contamination and contaminated ground-water using wells followed by treatment. This approach is termed pump-and-treat. It led to perpetual remediation at many contaminated sites, often because many sources of contamination cannot be effectively removed. This is especially true when nonaqueous-phase liquids (NAPLs) such as gasoline (lighter than water, LNAPLs) and chlorinated solvents (denser than water, DNAPLs) remain in the subsurface, acting as ongoing sources of ground-water contamination. DNAPLs are particularly troublesome because the dense liquid can migrate deep below the water table. With the source remaining, pump-and-treat could operate in perpetuity, protecting potential receptors by cutting off the contaminant plume, but presenting ongoing costs. So, alternate remedial strategies were sought. Two additional approaches have emerged.
Industry:Science
Dimming of light from the stars due to absorption and scattering by grains of dust in the interstellar medium. In the absorption process the radiation disappears and is converted into heat energy in the interstellar dust grains. In the scattering process the direction of the radiation is altered. Interstellar extinction produces a dimming of the light from stars situated beyond interstellar clouds of dust according to the equation <i>F</i><sub>λ</sub> = <i>F</i><sub>λ</sub>(0)<i>e</i><sup>−τλ</sup>, where <i>F</i><sub>λ</sub> is the observed flux of radiation from the star at a wavelength λ, <i>F</i><sub>λ</sub>(0) the flux that would be observed in the absence of interstellar extinction, and τ<sub>λ</sub> the dimensionless optical depth for interstellar extinction at λ. Measures of the radiation from pairs of stars of similar intrinsic properties but with differing amounts of interstellar extinction can be used to obtain information about τ<sub>λ</sub>, which can then be used to provide clues about the nature of the interstellar dust grains.
Industry:Science
Embryonated eggs are among the most useful and available forms of living animal tissue for the isolation and identification of animal viruses, for titrating viruses, and for quantity cultivation in the production of viral vaccines. The embryo proper, chorioallantoic membrane, yolk sac, allantoic sac, or amniotic sac may be inoculated in hens' eggs of various ages, so that a wide choice of types of tissue is available to fit the characteristics of the virus under study or for special studies. The chorioallantoic membrane is frequently used; in some infections, such as smallpox, vaccinia, and herpes simplex, characteristic lesions are produced which in some cases may resemble those in the natural host. For example, smallpox virus when cultured on the chorioallantoic membrane produces pocks and typical inclusions within the infected cells. When the embryo is inoculated, characteristic skin eruptions appear. Influenza virus, however, when inoculated into the amniotic cavity, does not give rise to pathology like that of the natural infection.
Industry:Science
Calibrated standard sources of radioactive substances used to determine, by comparison, the strength or activity of samples of the same substances in terms of the number of radioactive atoms they contain or in terms of some figure proportional to this number. The calibration of the standard source in terms of the number of radioactive atoms is usually an elaborate procedure but need only be carried out once, and the calibration may be made at a standardizing laboratory, such as the National Institute of Standards and Technology, having special equipment for the work. Comparison between a sample and the standard is usually made by finding the ratio of the response of an ionization chamber, or other detector of radiation, to the radiation from a sample and from the standard. In each case the intensity of the radiation, and therefore the response of the detector under identical conditions, is proportional to the number of radioactive atoms in the source, because this number is also proportional to the activity or disintegration rate of a source.
Industry:Science
Coral reefs are among the most diverse communities on Earth. This diversity occurs at low (species) and high (phylum) taxonomic levels and includes cryptofauna living within the substrate (for example, boring sponges, worms, and bivalves; sessile encrusting bryozoans, sponges, tunicates, and worms; motile worms, mollusks, echinoderms, and crustaceans), sessile epifauna on the substrate surface (for example, scleractinian corals, sponges, and coralline and fleshy algae), and suprabenthic fishes in the overlying water column. Approximately 93,000 species have been described globally on modern reefs, although 500,000 to 1 million species are estimated to inhabit reefs (in comparison with 20 million species in tropical rainforests). In addition to the tropical location of coral reefs, a number of other factors appear to be responsible for this high biodiversity, including elaborate biologically generated physical heterogeneity, sophisticated specializations, common sibling species (morphologically similar), and coevolved associations among species.
Industry:Science
Detection of gases, associated with all mineral deposits, can lead to the discovery of deposits beneath the ground surface. Carbon dioxide, hydrogen sulfide, and other gases are common constituents of the hydrothermal solutions that transport ore minerals. Other gases are produced when those minerals react with ground water or with microorganisms. Hydrocarbon liquids and gases such as methane and ethane are produced when petroleum and natural gas deposits are formed. Hydrocarbon gases are also found around metallic ore deposits. All gases have a natural tendency to migrate from areas of high pressure to areas of low pressure, that is, from depth to the surface. They migrate slowly by diffusion through rock, or rapidly through permeable zones such as faults, fractures, or breccia zones. The gases are sampled at or near the surface, and are analyzed to measure gas species and their concentration. When the results are plotted on maps, anomalous areas of high or low concentrations are readily seen and may indicate buried mineral deposits or faults.
Industry:Science
