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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 ability to fix atmospheric nitrogen into a form that can be used for plant growth is confined to bacteria and cyanobacteria. Plants fix nitrogen only by virtue of associations with these simple organisms. The best-known associations are the symbioses of <i>Rhizobium</i> bacteria with agricultural legumes, such as clovers, peas, and beans. Rhizobia stimulate the formation of root nodules, which provide a specialized environment within which high rates of nitrogen fixation can occur. Nitrogen fixation not only supports plant growth independent of mineral nitrogen in the soil but also can improve soil nitrogen status as plant residues, notably leaves and fine roots, decay and are mineralized. Accurate estimates of amounts of nitrogen fixed are difficult to obtain, but a well-nodulated, young, densely planted stand of nitrogen-fixing trees may fix 80–200 kg of nitrogen per hectare per year, similar to rates reported for some leguminous crops.
Industry:Science
The Dawn mission is designed to perform a scientific investigation of the main-belt asteroid (4) Vesta and the dwarf planet (1) Ceres in order to obtain new information to help answer questions about the formation and evolution of the early solar system. It will be the first mission to orbit a main-belt asteroid and the first to orbit two target bodies. The mission is enabled by an ion propulsion system, which the spacecraft will use to rendezvous with and go into orbit about each of these bodies. Dawn is the ninth project in the Discovery Program of the National Aeronautics and Space Administration (NASA), and was launched on September 27, 2007.
Industry:Science
The bound state of the electron and its antimatter counterpart, the positron. Positronium (abbreviated Ps) is perhaps the simplest bound state, since the constituents are structureless and the electromagnetic binding force is well understood. As in the hydrogen atom, the states of positronium are quantized. The spins of the two spin-<sup>1</sup>/<sub>2</sub> constituents combine to yield total spin zero (singlet state) or one (triplet state). Singlet and triplet states are called parapositronium (p-Ps) and orthopositronium (o-Ps), respectively. States of positronium are labeled by principal quantum number <i>n</i>, orbital angular momentum, total spin, and total angular momentum (orbital plus spin). The energy levels are approximately −6.80 eV/<i>n</i><sup>2</sup>, with numerous small corrections due to relativity, virtual annihilation, and other electromagnetic effects. Additional corrections from strong and weak interactions are negligible.
Industry:Science
The elements of the halogen family (fluorine, chlorine, bromine, and iodine) possess an ability to react with each other to form a series of binary interhalogen compounds (or halogen halides) of general composition given by XY; where <i>n</i> can have the values 1, 3, 5, and 7, and where X is the heavier (less electronegative) of the two elements. All possible diatomic compounds of the first four halogens have been prepared. In other groups a varying number of possible combinations is absent. Although attempts have been made to prepare ternary interhalogens, they have been unsuccessful; there is considerable doubt that such compounds can exist.
Industry:Science
The application of physics for purposes of civil or criminal law. Forensic science has been dominated by the fields of chemistry (mainly analytical chemistry) and biology (serology and DNA profiling). Indirectly, physics has contributed to forensic science via the invention of the microscope, the electron microscope, the mass spectrometer, and optical spectrometers; but directly, its role in forensic science has been minimal. Forensic physics has traditionally involved the measurement of density (soil and glass examination), index of refraction, and birefringence (fiber analysis, glass examination). In the last 25 years, the use of the photoluminescence phenomenon for physical evidence examination has emerged, with latent fingerprint detection the most notable application. In criminalistics, fingerprint detection is important because it provides absolute identity, and does not suffer from the contamination problems to which DNA profiling is prone.
Industry:Science
The cell has many vital parts. The mitochondria are the power plants that provide energy (adenosine triphosphate) for cellular processes, and the ribosomes are factories that make all the proteins and enzymes required for cellular functioning. DNA is an indispensible component of cells, since it contains the genetic instructions for cellular functioning, protein synthesis, and heredity. If DNA is damaged, it can be fixed or replaced by DNA repair enzymes, but if DNA damage is not corrected, cell mutation or death can occur. Over time, this damage can accumulate and lead to diseases such as cancer, Alzheimer's, Parkinson's, and cardiovascular disease.
Industry:Science
The generation of synthetic speech signals in order to convey information to listeners, usually based upon a verbal or textual request by the users. This speech synthesis typically employs a computer program and requires access to storage of portions of speech previously spoken by humans. The naturalness of the synthetic voice depends on several factors, including the vocabulary of words to pronounce, the amount of stored speech, and the complexity of the synthesis programs. The most basic voice response simply plays back appropriate short verbal responses, which are only copies of human speech signals stored using digital sampling technology. The most universal systems, on the other hand, are capable of transforming any given text into comprehensible speech for a given language. These latter systems so far exist for only 20 or so of the world's major languages, and are flawed in producing speech that, while usually intelligible, sounds unnatural.
Industry:Science
The difference in the geostrophic wind between two heights in the atmosphere over a given position on Earth. It approximates the variation of the actual winds with height for large-scale and slowly changing motions of the atmosphere. Such structure in the wind field is of fundamental importance to the description of the atmosphere and to processes causing its day-to-day changes. The thermal wind embodies a basic relationship between vertical fluctuations of the horizontal wind and horizontal temperature gradients in the atmosphere. This relationship arises from the combination of the geostrophic wind law, the hydrostatic equation, and the gas law.
Industry:Science
The branch of science that describes the effects of the interactions between charges due to their motion and spin. These may appear in various forms, including electric currents and permanent magnets. The interactions are described in terms of the magnetic field, although the field hypothesis cannot be tested independently of the electrokinetic effects by which it is defined. The magnetic field complements the concept of the electrostatic field used to describe the potential energy between charges due to their relative positions. Special relativity theory relates the two, showing that magnetism is a relativistic modification of the electrostatic forces. The two together form the electromagnetic interactions which are propagated as electromagnetic waves, including light. They control the structure of materials at distances between the long-range gravitational actions and the short-range “strong” and “weak” forces most evident within the atomic nucleus.
Industry:Science
The Large Hadron Collider (LHC) is located at the European Laboratory for Particle Physics (CERN) near Geneva, Switzerland. Currently in the final stage of commissioning (2008), it will be the most powerful particle physics instrument in the world. It consists of two rings in which two counterrotating beams of hadrons (protons) are accelerated to an energy of 7 teraelectronvolts (1 TeV = 10<sup>12</sup> eV) and brought into collision at four points around the ring containing particle detectors. The center-of-mass energy of 14 TeV will be more than seven times larger than the energy achieved in the currently operating Tevatron at Fermilab near Chicago.
Industry:Science
