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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.
A class of ferrimagnetic oxide materials that have the garnet crystal structure. The crystal structure contains three types of nonequivalent sites in the oxygen lattice which are occupied by metal ions. The sites are referred to as 16(<i>a</i>), 24(<i>c</i>), and 24(<i>d</i>). A metal ion in a 16(<i>a</i>) site is surrounded by six oxygen ions which are at the corners of the octahedron. The metal ions in the 24(<i>d</i>) sites are found in nonregular tetrahedrons formed by oxygen ions, while the metal ions in the 24(<i>c</i>) sites have eight oxygen-ion nearest neighbors to form a triangular dodecahedron at the corners of a distorted cube.
Industry:Science
A class of fine-grained clastic sedimentary rocks with a mean grain size of less than 0.0625 mm (0.0025 in.), including siltstone, mudstone, and claystone. One-half to two-thirds of all sedimentary rocks are shales.
Industry:Science
A class of fishes (Pisces) known from the Devonian Period, and a few that survived into the base of the Carboniferous. They were true fishes or gnathostomes, and can be distinguished from other fishes by the following characters: the gill chamber extends far under the cranium and is covered laterally by opercula; there is a neck joint between the cranium and the fused anterior vertebrae; often there is also a coaxial joint developed between the dermal bones of the cranial roof and shoulder girdle; the head and shoulder girdle are covered with dermal bones composed typically of cellular bone and superficially of semidentine instead of true dentine; the bones are commonly ornamented with tubercles or ridges; the endoskeleton is cartilage and may be calcified in a globular fashion or perichondrally ossified; the notochord is persistent, and the vertebrae consist only of neural and hemal arches; the tail is diphycercal or slightly heterocercal, and an anal fin is lacking.
Industry:Science
A class of fishes characterized by well-developed jaws and bony teeth; pectoral and pelvic girdles, each supporting paired fins; a cartilaginous skeleton that lacks true bone; toothlike scales of ectodermal and mesodermal origin; paired nostrils with blind olfactory sacs (not opening into the mouth); a vertebral column having either a straight or heterocercal posterior end; absence of a swim bladder; cranium without sutures; and internal fertilization.
Industry:Science
A class of fungi in the subdivision Mastigomycotina. They comprise a group of heterotropic, fungallike organisms that are classified with the zoosporic fungi (Mastigomycotina) but in reality are related to the heterokont algae. They are distinguished from other zoosporic fungi by the presence of biflagellate zoospores: the shorter, anteriorly directed flagellum contains two rows of tripartite hairs; the longer, posteriorly directed flagellum is naked and whiplash. Some taxa are nonzoosporic. The thallus may be unicellular, or mycelial and composed of filamentous hyphae that are coenocytic (without cross walls), at least in the early stages of development. The main component of the cell walls is cellulose, or cellulose and chitin. Asexual reproduction involves the release of zoospores from sporangia; in some taxa the sporangium germinates with outgrowth of a germ tube. Sexual reproduction occurs when an oogonial cell is fertilized by contact with an antheridium, resulting in one or more oospores. At least in some, possibly all, species, the thallus is diploid.
Industry:Science
A class of hexapod (six-legged) arthropods consisting of the orders Collembola and Protura. Class Parainsecta (also known as Ellipura) is one of several classifications of those hexapods, which, while similar to insects, are sufficiently different that most researchers believe they deserve separate class status.
Industry:Science
A class of highly luminous yellow stars that vary periodically in brightness. Approximately one out of a thousand of the intrinsically brightest stars in any galaxy, like the Milky Way Galaxy, is a classical Cepheid variable. Among the 6000 apparently brightest stars visible to the unaided human eye in the night sky, more than a dozen are Cepheids (including Delta Cephei, the prototype; Beta Doradus in the south; and Polaris, the Pole Star). Cepheids have the same yellow color as the Sun (and hence, similar surface temperatures), but they have larger radii and therefore are intrinsically 1000 to over 100,000 times more luminous. Named for their naked-eye prototype Delta Cephei, the Cepheids are very well understood, and have repeatedly proved to be immensely important to many aspects of modern astronomy. Not only are Cepheids bright (supergiant) stars, so that they can be seen over large distances, but also they are at a particular stage in their evolution such that they are unstable to periodic oscillations. Motion of their surface manifests itself as regular changes in the apparent luminosity with time and so they can be easily identified.
Industry:Science
A class of high-molecular-weight molecules, usually with colloidal properties, which in an appropriate solvent or swelling agent are able to produce gels (highly viscous suspensions or solutions) at low dry-substance content. The molecules are either hydrophilic or hydrophobic; that is, they do or do not have an affinity for water. The term gum is applied to a wide variety of substances of gummy characteristics, and therefore cannot be precisely defined.
Industry:Science
A class of largely extinct gymnosperms (Pinophyta). Included orders are Calamopityales, Callistophytales, Arberiales, Peltaspermales, Ginkgoales, Leptostrobales, Caytoniales, Pentoxylales, and Ephedrales. The most ancient taxa, Calamopityales and Callistophytales, lived during the Carboniferous; the Arberiales, from late Carboniferous into the Triassic; the Peltaspermales, from Permian through Jurassic; the Leptostrobales and Caytoniales, from Triassic into the Cretaceous; and Ginkgoales, predominantly, from Triassic into the Cretaceous periods, with one species, <i>Ginkgo biloba</i>, persisting to the present. Ephedrales is the only largely extant group, but has a pollen fossil record beginning in the Upper Triassic.
Industry:Science
A class of lower green plants called liverworts that belong to the division Bryophyta. The class is divided into approximately 225 genera and 8500 species. Although there is a great diversity of external form, most of the gametophytes (gamete-producing plants) are dorsoventrally differentiated. These plants are considered among the most primitive of the existing land plants. Fossil remains of liverworts have been found in both the Devonian and Carboniferous. Since the fossils found do not differ significantly from modern liverworts, they are of little value in ascertaining phylogenetic relationships. Liverworts are widely distributed over the world, but have their greatest diversity in the tropics of the Americas and East Indies.
Industry:Science
