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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.
Cold-seep ecosystems are biological communities sustained by the seepage from the ocean subsurface of cold fluid containing chemicals (especially methane but also sulfide). Since their discovery in 1984, cold-seep ecosystems have been described from various oceans and seas. More than 200 seep species have been described so far, and many of them (approximately one-third) are symbiont-bearing species. In methane-rich seep environments, symbioses are developed between gutless bivalve mollusks, roundworms, and tubeworms, which may host in their soft tissues (gills, for example) dense communities of methane-consuming and sulfide-oxidizing bacteria. By a microbial process known as chemosynthesis, these endosymbiotic bacteria use the chemical energy derived from the oxidation of sulfide and methane to synthesize organic compounds that serve as food for their mollusk and worm hosts. In marine sediments of a methane seep, sulfide-oxidizing activity is also performed by free-living bacteria that may develop as thick mats composed of giant filaments. This microbial biomass may directly serve as nourishment for many organisms, in contrast to the symbiotic relationships in the gutless and/or mouthless animals.
Industry:Science
During the last 540 million years, the history of life on Earth has been punctuated by severe mass extinctions, brief periods when biodiversity collapsed. At the boundary between the Paleozoic and Mesozoic eras (approximately 252 million years ago), the end-Permian mass extinction was the most devastating global-scale event ever recorded, resulting in the loss of more than 90% of marine species. During long and intense debate about the potential causes of this major crisis, considerable effort has been devoted to investigating the unusual ecological patterns that arose during its aftermath. Until recently, several studies suggested that the biosphere took between 5 and 30 million years to reach the levels of biodiversity seen before the extinction. However, recent findings on pelagic organisms such as ammonoids and conodonts indicate a rapid and explosive recovery in less than 2 million years. This duration contrasts radically with patterns observed for benthic biota (living on or within the sea floor), which are based mainly on fragmentary data. It also suggests that recovery rates for numerous taxa need to be reevaluated and that ecosystem reorganization may occur rapidly after a mass extinction.
Industry:Science
As length scales shrink and demands on magnetic materials increase, engineers are increasingly looking toward molecule-based materials to develop the next generation of magnetic devices. These materials show promise for specialized applications, including magneto-optic recording, magnetic shielding, components of lightweight transformers, generators and motors, photomagnetic switches, sensitive molecular sensors, and spintronic devices. The appeal of molecule-based magnets is a result of their highly tunable nature, transparency, low density, moderate solubility in organic solvents, and facile preparation under mild conditions. This is in contrast to the current technologically useful magnetic atom-based (inorganic) materials, which have greater densities and require high temperatures and/or pressures to prepare them. Through molecular synthesis, organic chemistry provides the ability to fine-tune structures and properties to a much greater extent than is possible for inorganic materials. The possibility of combining multiple physical properties, such as optical/magnetic, conducting/magnetic, and so forth, has prompted the quest for hybrid materials, many of which consist of polymeric molecular magnets.
Industry:Science
Hyperspectral imagery offers new and unique opportunities for landscape mapping. It is an offshoot of multispectral imagery, which measures reflected light in 1 to approximately 10 bands and has been an important tool in landscape mapping since deployment of <i>Landsat</i> in the 1970s. Both methods measure bandwidths in the infrared, visible, and ultraviolet regions of light. Compared to multispectral sensors used for most remote mapping prior to the late-1990s, however, hyperspectral sensors record narrower bandwidths and more bandwidths of reflected visible and shortwave infrared light. For example, the AVIRIS (Airborne Visible/Infra-Red Imaging Spectrometer) hyperspectral sensor records 224 different bandwidths of light between 400 and 2500 nanometers. In contrast, the <i>Landsat</i> multispectral Thematic Mapper records reflected light in only six bands. The narrower bandwidths of hyperspectral sensors make possible the detection of specific features that have strong reflectance in a narrow band of light (such as certain minerals). The larger number of bands enables detection of subtle differences between similar features, because the cumulative differences become large when summed over many bands.
Industry:Science
Any one of the number of independent ways in which the space configuration of a mechanical system may change. A material particle confined to a line in space can be displaced only along the line, and therefore has one degree of freedom. A particle confined to a surface can be displaced in two perpendicular directions and accordingly has two degrees of freedom. A particle free in physical space has three degrees of freedom corresponding to three possible perpendicular displacements. A system composed of two free particles has six degrees of freedom, and one composed of <i>N</i> free particles has 3<i>N</i> degrees. If a system of two particles is subject to a requirement that the particles remain a constant distance apart, the number of degrees of freedom becomes five. Any requirement which diminishes by one the degrees of freedom of a system is called a holonomic constraint. Each such constraint is expressible by an equation of condition which relates the system's coordinates to a constant, and may also involve the time. When applied to systems of particles, a holonomic constraint frequently has the geometrical significance of confining a particle to a specified surface, which may be time-dependent.
Industry:Science
Fourth-generation (4G) mobile communications concepts and technologies are beginning to evolve. In the simplest form, 4G consists of an evolution beyond the third-generation (3G) cellular communication systems now at or near deployment worldwide. Cellular communications has evolved from the original analog formats, called 1G, to the digital formats now in use and labeled 2G, to 2.5G and 3G. Most treatments of 4G involve a much more expansive view of the wireless services that are possible, and often encompass a vision of seamless, ubiquitous connectivity with cellular networks, wireless local area networks (WLANs), and wireless personal area networks (WPANs, wireless networks that cover a very short distance, and may be used to interconnect devices on one's person or very close vicinity), as well as the connections into fixed wireless and wired networks.
Applications and services available through any network are also made available on any other wireless network. The wireless world, a term first used by the Wireless World Research Forum (WWRF) in its <i>Book of Visions</i> to describe 4G, would be a fundamentally better wireless communications and networking system than those currently in use or in deployment.
Industry:Science
Capabilities-based planning (CBP) is a general approach to strategic planning, but one associated primarily with the U.S. Department of Defense (DoD). The DoD announced the shift to capabilities-based planning as a major theme in 2001, “to shift the basis of defense planning from the ‘threat-based' model that has dominated thinking in the past to a ‘capabilities-based' model for the future. This model focuses more on how an adversary might fight rather than specifically who the adversary might be or where a war might occur.” A key to planning would be confronting the profound uncertainties that make it impossible to know the identities of future combatant powers or the circumstances of conflict many years in advance. Planning would maintain a broad “portfolio” of military capabilities in functional areas such as power projection and effective use of space and information technology.
Another emphasis was to be managing strategic risks. The DoD is in the process of implementing capabilities-based planning. Other federal, state, and national organizations (for example, the Department of Homeland Security) have also adopted this approach, or approaches that borrow from it. What, then, is capabilities-based planning?
Industry:Science
Clusters are aggregates of atoms (or molecules) containing between three and a few thousand atoms that have properties intermediate between those of the isolated monomer (atom or molecule) and the bulk or solid-state material. The study of such species has been an increasingly active research field since about 1980. This activity is due to the fundamental interest in studying a completely new area that can bridge the gap between atomic and solid-state physics and also shows many analogies to nuclear physics. However, the research is also done for its potential technological interest in areas such as catalysis, photography, and epitaxy.
A characteristic of clusters which is responsible for many of their interesting properties is the large number of atoms at the surface compared to those in the cluster interior. For many kinds of atomic clusters, all atoms are at the surface for sizes of up to 12 atoms. As the clusters grow further in size, the relative number of atoms at the surface scales as approximately 4<i>N</i><sup>−1/3</sup>, where <i>N</i> is the total number of atoms. Even in a cluster as big as 10<sup>5</sup> atoms, almost 10% of the atoms are at the surface. Clusters can be placed in the following categories:
Industry:Science
Any of a class of soluble proteins (molecular weight less than 100,000 daltons, or 100 kD) that are released by a cell to send messages that are delivered to the same cell (autocrine), an adjacent cell (paracrine), or a distant cell (endocrine). The cytokine binds to a specific receptor and causes a change in function or in development (differentiation) of the target cell. Cytokines are involved in reproduction, growth and development, normal homeostatic regulation, response to injury and repair, blood clotting, and host resistance (immunity and tolerance).
Unlike cells of the endocrine system, many different types of cells can produce the same cytokine, and a single cytokine may act on a wide variety of target cells. Further, several cytokines may produce the same effect on a target, so the loss of one type of cytokine may have few if any consequences for the organism; this situation is called redundancy. Finally, the response of a target cell may be altered by the context in which it receives a cytokine signal. The context includes other cytokines in the milieu and extracellular matrix. Thus has developed the concept of cytokines as letters of an alphabet that combine to spell words which make up a molecular language.
Industry:Science
Complex hydrides containing a hydride ligand bonded to a central atom. The prefix hydro instead of hydrido is sometimes used. Sodium tetrahydridoborate, NaBH<sub>4</sub> (or sodium tetrahydroborate, originally called sodium borohydride), and lithium tetrahydridoaluminate, LiAlH<sub>4</sub> (originally called lithium aluminum hydride), are important reducing agents in synthetic and industrial reactions. NaBH<sub>4</sub> is employed in aqueous or alcoholic solutions, and LiAlH<sub>4</sub> is employed in ethers. Sodium cyanotrihydridoborate, NaBH<sub>3</sub>CN, can be used in acidic medium. A family of aluminum-based reducing agents is now available commercially, including sodium diethyldihydridoaluminate, NaAlH<sub>2</sub>(C<sub>2</sub>H<sub>5</sub>)<sub>2</sub>; sodium tri-<i>tert</i>-butoxohydridoaluminate, NaAlH(O-<i>t-</i>C<sub>4</sub>H<sub>9</sub>)<sub>3</sub>; and sodium bis(2-methoxyethoxo)-dihydridoaluminate, NaAlH<sub>2</sub>(OCH<sub>2</sub>CH<sub>2</sub>OCH<sub>3</sub>)<sub>2</sub>. All are soluble in aromatic hydrocarbons. They are rather expensive, but their specific reducing powers make them attractive for synthesizing high-value products, such as pharmaceuticals, flavorings, fragrances, dyes, and insecticides.
Industry:Science
