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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.
The chemical or biological conversion of atmospheric nitrogen (N<sub>2</sub>) into compounds which can be used by plants, and thus become available to animals and humans. In the 1990s, chemical and biological processes together contributed about 260 million tons (230 million metric tons) of fixed nitrogen per year globally. Industrial production of nitrogen fertilizer accounted for about 85 million tons (80 million metric tons) of nitrogen per year, while spontaneous chemical processes, such as lightning, ultraviolet irradiation, and combustion, leading to the synthesis of nitrogen oxides from O<sub>2</sub> and N<sub>2</sub>, may have accounted for 44 million tons (40 million metric tons) per year. The remainder, roughly half of the global input of newly fixed nitrogen, arose from biological processes. World agriculture, which is very dependent on nitrogen fixation, is increasingly reliant on chemical nitrogen sources.
Industry:Science
The generation of ova or eggs, the female gametes. Primordial germ cells, once they have populated the gonads, proliferate and differentiate into either sperm in the testis or ova in the ovary. The decision to produce either motile spermatocytes or more sedentary oocytes is based primarily on the genotype of the embryo. In rare cases, this decision can be reversed by the hormonal environment of the embryo, so that the sexual phenotype may differ from the genotype. Formation of the ovum most often involves substantial increases in cell volume as well as the acquisition of organellar structures that adapt the egg for reception of the sperm nucleus, and support of the early embryo. In histological sections, the structure of the oocyte often appears somewhat random, even chaotic, but as the understanding of its chemical and structural organization increases, an elegant but still somewhat cryptic order begins to emerge.
Industry:Science
The developing field of molecular electronics has come to encompass many types of molecular electronic devices, including polymer-based light-emitting-diode (LED) displays, solar energy conversion devices, and a variety of chemical sensors. A characteristic feature of most molecular electronic devices is that they involve an intimate coupling of molecular materials with conventional solid-state electronic materials. A very promising subdiscipline within the field of molecular electronics involves the use of individual molecules or molecular aggregates in place of solid-state materials as active elements in circuits designed to accomplish logic functions. Such circuits are being considered as possible building blocks for futuristic molecule-based computing devices. A great attraction of such devices is the potential for miniaturizing computing devices, thereby increasing their power and enabling entirely new applications.
Industry:Science
The blackbody radiation left over from the origin of the universe, also known as the cosmic microwave background (CMB). This radiation was emitted before any astronomical objects such as stars, galaxies, or quasars existed, and is now observed to be like the thermal emission from a black object with a temperature of 2.725 K (degrees above absolute zero, or −454.8°F). Blackbody radiation is emitted by an isothermal object that absorbs all incident radiation. Its spectrum, or amount of power at different frequencies, depends only on its temperature and is given by the Planck function. The energy density of this radiation, which peaks at wavelengths near 1 mm, is larger than that of any other cosmic radiation field. Its existence was predicted in 1947 and 1948 by George Gamow, Ralph Alpher, and Robert Herman as part of their model for the formation of the elements during a hot dense phase in the early history of the universe.
Industry:Science
The <i>Galileo</i> spacecraft, which arrived at Jupiter on December 7, 1995, is conducting one of the most historic planetary exploration missions ever performed. The spacecraft consisted of two main components: an atmospheric entry probe and a planetary orbiter. The Probe plunged into the atmosphere of Jupiter on December 7, accomplishing the first direct sampling of the atmosphere of one of the outer giant planets and surviving the most difficult atmospheric entry ever attempted. On the same date the Orbiter was the first ever to be placed in orbit about Jupiter, and will return data about the Jovian system for a total of almost 2 years. Before reaching Jupiter, the spacecraft took the first closeup pictures of asteroids, discovering that one of them had a small satellite (about 1 mi or 1.6 km in diameter), and was the only platform that had a direct view of the impact of the comet Shoemaker-Levy 9 with Jupiter in July 1994.
Industry:Science
The ability of animals to survive and function at widely different temperatures is a result of specific physiological adaptations. Temperature is an all-pervasive attribute of the environment that limits the activity, distribution, and survival of animals. Ocean temperatures range from 28 to 86°F (−2 to 30°C), but considerably warmer temperatures are found near deep-sea hydrothermal vents (up to 662°F or 350°C), backwaters of desert streams (109°F or 43°C), and geothermal springs (194–212°F or 90–100°C). Air temperatures range from −94°F (−70°C) in polar regions to 176°F (80°C) at the desert surface. Although some bacteria and blue-green algae live at temperatures up to 230°F (110°C), life processes are generally restricted to the temperatures between 32 and 113°F (0 and 45°C), and most animals live within an even narrower range. Limits for reproduction and development are generally narrower than those for survival of adults.
Industry:Science
The field of chemistry that includes all chemical measurements, such as the measurements of atomic and molecular weights and sizes, gas volumes, vapor densities, deviation from the gas laws, and the structure of molecules. In the long struggle to determine the relative weights of the atoms, scientists relied upon combining ratios, specific heats, and measurements of gas volumes. All such measurements, and the calculations that relate them to each other, constitute the field of stoichiometry. Since measurements are expressed in mathematical terms, stoichiometry can be considered to be the mathematics of general chemistry. Thus, stoichiometry is not part of inorganic, organic, physical, or analytical chemistry, but is an essential part of all of them. Chemistry is an exact science, and it depends upon exact measurements of weights, lengths, and volumes, and on the amounts of energy which are absorbed or evolved in chemical reactions.
Industry:Science
The continuous or excessive use of alcohol (ethanol) with associated pathologic results. Alcoholism is characterized by constant or periodic intoxication, although the pattern of consumption varies markedly. Individuals admitted for the first time to an alcoholism treatment center typically have been consuming 3–4 oz (80–100 g) of pure alcohol per day, corresponding to seven to nine drinks or bottles of beer or glasses of wine. Studies have shown that problem drinking in these populations starts at about 2 oz/day (60 g/day), that is, four to five drinks per day, and that these are consumed in rapid succession, leading to intoxication on three or more days per week. Individuals who consume these levels of alcohol have a greater-than-average risk of developing alcoholic liver cirrhosis. However, the levels should not be taken as absolute, since they can vary greatly in different individuals, according to body weight and other factors.
Industry:Science
Surface plasmon resonance (SPR) spectroscopy is a real-time, optical technique that has gained widespread use in surface science and biomolecular interaction analysis since the early 1990s. In SPR experiments, molecules of interest are immobilized on a solid substrate, and their interaction with ligands is monitored to elicit information such as the binding affinity. The SPR data—reflectivity spectra or sensorgrams—can be used to determine bulk concentration and rate constants, as well as to extract parameters on binding energy, recognition sites, interaction mechanisms, and stoichiometry. The key advantage of SPR spectroscopy over conventional fluorescence or radiological assays in biomolecular interaction analysis is that no labeling is required. Although fluorescent labels allow high detection sensitivity, they have the drawback of potentially altering the native state of the studied species, particularly in proteins and peptides.
Industry:Science
The application of chemical techniques to the study of archeological finds, natural or anthropogenic, in order to ascertain their composition or, in some cases, their age. Traditional chemical analysis uses wet methods, in which a sample is brought into solution and its components are assayed by precipitation or titration. These methods were applied to ancient coins as early as the late eighteenth centuary. The obvious need to minimize damage to an irreplaceable object spurred the development of microchemical techniques. Modern analysis relies on instrumental methods that require only very small samples or are entirely nondestructive. Although these methods rely on physical phenomena rather than chemical transformation, all procedures that are capable of the qualitative and quantitative determination of the atomic or molecular composition of the object under study are usually included under the broad heading of archeological chemistry.
Industry:Science
