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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 small class of spindle-shaped, spirally pleated, primitive echinoderms in the subphylum Echinozoa, from the Early Cambrian (<i>Nevadella</i> Zone) in eastern California, western Nevada, and eastern British Columbia. Since their discovery in the early 1960s, three genera and six species have been described based on nearly 600 complete specimens, making helicoplacoids the most diverse and abundant echinoderm class known from the Early Cambrian. Most helicoplacoids have a spindle-shaped theca or body with diagonally spiraled pleats, each made up of three rows of flexibly sutured plates forming an interambulacral ridge. Smaller-plated ambulacra spiral around the theca every 7–13 pleats; the ambulacral plates cover a central food groove that has pores for tube feet on each side. The original authors inferred that the mouth was at the more rounded pole of the theca and that a single long ambulacrum branched once about one-third of the way down the theca. However, it has been argued that the mouth was located where the ambulacra split (see <b>illus.</b>), so that three ambulacral branches lead away from it, one spiraling partway down the theca and two spiraling up the theca a few pleats apart. No anal opening or pyramid has been found on any of the known specimens.
Industry:Science
A small class of the plant division Bryophyta, made up of plants commonly called hornworts. There is a single order with six genera.
Industry:Science
A small cluster of stars that makes up the nearest well-defined open cluster (galactic cluster) to the Earth. With a total mass of about 300 suns and a population of 400–500 mostly low-mass stars, the Hyades is a typical example of the 2000 or so small star clusters in the Milky Way Galaxy. Most of its stars are located in a loose, roughly spherical system approximately 40 light-years (2.4 × 10<sup>14</sup> mi or 3.8 × 10<sup>14</sup> km) in diameter. It is located primarily in the constellation Taurus, the Bull, and forms the faint stellar background to the V-shaped asterism that defines the head of the Bull.
Industry:Science
A small deciduous tree, <i>Prunus amygdalus</i> (also known as <i>P. dulcis</i> or <i>Amygdalus communis</i>), closely related to the peach and other stone fruits and grown widely for its edible seeds. The fruit, classified botanically as a drupe (see <b>illus.</b>), is analogous to that of the peach except that the outer fleshy (mesocarp) layer does not enlarge in size during the latter part of the fruit growth-curve. Instead it splits (dehisces) as it nears maturity and separates from the shell (endocarp) and then dries. The nut with the kernel, or seed, within is then released.
Industry:Science
A small deciduous tree, <i>Punica granatum</i>, belonging to the plant order Myrtales. Pomegranate is grown as an ornamental as well as for its fruit. Propagation is by cuttings and occasionally by layering. The pomegranate is a native of Asia, and was described by writers as early as 300 <small>B</small>.<small>C</small>. It was originally known for its medicinal qualities, and cures for various ills were attributed to the fruit juice, the rind, and the bark of the roots. The fruit is a reddish, pomelike berry, containing numerous seeds embedded in crimson pulp, from which an acid, reddish juice may be obtained. Limited quantities are grown in California and the Gulf states.
Industry:Science
A small difference between the different isotopes of an element in the transition energies corresponding to a given spectral-line transition. For an electronic spectral-line transition between two energy levels <i>a</i> and <i>b</i> in an atom or ion with atomic number <i>Z</i>, the small difference Δ<i>E</i><sub><i>ab</i></sub> = <i>E</i><sub><i>ab</i></sub>(<i>A</i>′) − <i>E</i><sub><i>ab</i></sub>(<i>A</i>) in the transition energy between isotopes with mass numbers <i>A</i>′ and <i>A</i> is the isotope shift. It consists largely of the sum of two contributions, the mass shift (MS) and the field shift (FS), also called the volume shift. The mass shift is customarily divided into a normal mass shift (NMS) and a specific mass shift (SMS); each is proportional to the factor (<i>A</i>′ − <i>A</i>)/<i>A</i>′<i>A</i>. The normal mass shift is a reduced mass correction that is easily calculated for all transitions. The specific mass shift is produced by the correlated motion of different pairs of atomic electrons and is thus absent in one-electron systems.
Industry:Science
A small extinct class and one of the most primitive types of rhynchonelliformean brachiopods. The kutorginates were widely distributed from the Early Cambrian and became extinct at the end of the Middle Cambrian.
Industry:Science
A small extinct class of relatively advanced blastozoan echinoderms containing five genera (three named), ranging from the middle Early Ordovician to the early Late Ordovician in eastern Canada; northeastern, eastern, south-central, and western United States; south and north Wales; and near St. Petersburg, western Russia. Parablastoids have a bud-shaped theca or body with well-developed pentameral symmetry. Thecal plates include basals, small or large radials, and sometimes other small plates in the lower theca; large distinctive triangular-to-parabolic deltoids between the ambulacra in the upper theca (see <b>illustration</b>); and small oral plates and an oral crest surrounding and covering the mouth on the summit. Parablastoids have single or multiple slits through the lower deltoids that are connected by internal folds (cataspires) to pores that open between the single ambulacral plates at the edge of each ambulacrum; presumably they were respiratory organs. Short-to-long biserial brachioles were attached to the edges of the five ambulacra and served as the main food-gathering structures; when not feeding, the brachioles folded in to lie against a high T-shaped ambulacral crest in the center of each ambulacrum in the best-known genus. A stem with one-piece columnals attached the theca to the sea floor, suggesting that parablastoids were attached, medium- to high-level, suspension feeders. Some parablastoids are found in bank or reef deposits, suggesting they may have been adapted for rough-water conditions. Although they converged on blastoids in thecal design and way of life, parablastoids had differences in their plating, ambulacra, and respiratory structures that indicate a separate origin and evolutionary history. This justifies assigning parablastoids and blastoids to different blastozoan classes.
Industry:Science
A small extinct order of articulated brachiopods that ranges in age from Early to Middle Cambrian and includes the earliest known calcitic brachiopods.
Industry:Science
A small extinct order of inarticulate brachiopods that ranges in age from Early Cambrian to Middle Ordovician. The shell is chitinophosphatic in composition, and its outline is circular or elliptical. The ventral (pedicle) valve is more convex than the dorsal (brachial) valve. The pedicle was absent or emerged between the valves. The ventral valve has a flattened posterior area (pseudointerarea) that is divided by a triangular notch which is closed to a variable extent by a plate (homeodeltidium). Comparable, but not as extensive, structures occur at the posterior end of the dorsal (brachial) valve. The muscle scars are unusual compared to other inarticulates, and form narrow triangular tracks radiating from the posterior extremity of each valve (see <b>illustration</b>). Except for their shell composition and lack of articulation, the Paterinida resemble articulate brachiopods. Members were presumably epifaunal and sessile.
Industry:Science
