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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 term considered by some to mean the entrance, growth, and multiplication of a microorganism (pathogen) in the body of a host, resulting in the establishment of a disease process. Others define infection as the presence of a microorganism in host tissues whether or not it evolves into detectable pathologic effects. The host may be a bacterium, plant, animal, or human being, and the infecting agent may be viral, rickettsial, bacterial, fungal, or protozoan.
Industry:Science
A term expressing the density of luminous flux incident on a surface. This word has been proposed by the Colorimetry Committee of the Optical Society of America to replace the term illumination. The definitions are the same. The symbol of illumination is <i>E</i>, and the equation is <i>E</i> = <i>dF</i>/<i>dA</i>, where <i>A</i> is the area of the illuminated surface and <i>F</i> is the luminous flux.
Industry:Science
A term for the vegetative (morphological) form of the plant body. A related term is growth form but a theoretical distinction is often made: life form is thought by some to represent a basic genetic adaptation to environment, whereas growth form carries with it no connotation of adaptation and is a more general term applicable to structural differences.
Industry:Science
A term generally used to refer to the elevation of the lower edge of a snow field. In mountainous areas, it is not truly a line but rather an irregular, commonly patchy border zone, the position of which in any one sector has been determined by the amount of snowfall and ablation. These factors may vary considerably from one part to another.
In regions where valley glaciers descend to relatively low elevations, the summer snow line on intervening rock ridges and peaks is often much higher than the snow line on the glaciers, and in most instances it is more irregular and indefinite. If by the end of summer it has not disappeared completely from the bedrock surfaces, the lowest limit of retained snow is termed the orographical snow line, because it is primarily controlled by local conditions and topography. On glacier surfaces it is sometimes referred to as the glacier snow line or névé line (the outer limit of retained winter snow cover on a glacier).
Industry:Science
A term generically synonymous with perpendicular, which often refers specifically to a line that goes through a point <i>P</i> of a curve <i>C</i> and is perpendicular to the tangent to <i>C</i> at <i>P</i>. If a plane curve <i>C</i> has equation <i>y</i> = <i>f</i>(<i>x</i>), in rectangular coordinates the normal (line) to <i>C</i> at <i>P</i>(<i>x</i><sub>0</sub>,<i>y</i><sub>0</sub>) has slope −1/<i>f</i><sup>′</sup>(<i>x</i><sub>0</sub>), provided <i>f</i><sup>′</sup>(<i>x</i><sub>0</sub>) ≠ 0. The expression <i>f</i><sup>′</sup>(<i>x</i><sub>0</sub>) denotes the derivative of <i>f</i>(<i>x</i>), evaluated for <i>x</i>=<i>x</i><sub>0</sub>, and so the normal has equation <i>y</i> − <i>y</i><sub>0</sub> = (−1/<i>f</i><sup>′</sup>(<i>x</i><sub>0</sub>)) (<i>x</i> − <i>x</i><sub>0</sub>). If curve <i>C</i> is not a plane curve, all normal lines of <i>C</i> at point <i>P</i> on <i>C</i> lie in a plane, the normal plane of <i>C</i> at <i>P</i>. For other uses of normal (for example, normal form of equation of a line or a plane)
Industry:Science
A term having a variety of specific applications but generally meaning the maximum current which can be obtained under certain conditions.
Industry:Science
A term in thermodynamics which in different treatments may designate either of two functions defined in terms of the internal energy <i>U</i> or enthalpy <i>H</i>, and the temperature-entropy product <i>TS</i>.
Industry:Science
A term most commonly used to refer to the subjective feelings that accompany the need for food; however, the study of this topic has come to include consideration of the overall control of food intake. More specifically, experimental work on the problem of hunger has been concerned with the sensory cues that give rise to feelings of hunger, the physiological mechanisms that determine when and how much food will be ingested, and the mechanism governing the selection of the food to be eaten.
Industry:Science
A term possessing genetic implications, originally defined as an aquatic sediment rich in organic matter that formed under reducing conditions (lack of dissolved oxygen in the water column) in a stagnant water body. This contrasts with the term gyttja, which is also a sediment high in organic carbon content but which formed under inferred oxygenated conditions in the water column down to the sediment-water interface (thus benthic organisms may be present).
Such inferences about water-column dissolved-oxygen contents are not always easy to make for ancient environments. Therefore, the term sapropel or sapropelic mud has been used loosely to describe any discrete black or dark-colored sedimentary layers (>1 cm or 0.4 in. thick) that contain greater than 2 wt % organic carbon. Sapropels may be finely laminated (varved) or homogeneous, and may less commonly exhibit structures indicating reworking or deposition of the sediment by currents. Sapropels largely contain amorphous (sapropelic) organic matter derived from planktonic organisms (such as planktonic or benthic algae in lakes or plankton in marine settings). Such organic matter possesses a large hydrogen-to-carbon ratio; therefore, sapropelic sequences are potential petroleum-forming deposits. The enhanced preservation of amorphous organic matter in sapropels may indicate conditions of exceptionally great surface-water productivity, extremely low bottom-water dissolved-oxygen contents, or both. Some sapropels may, however, contain substantial amounts of organic matter derived from land plants.
Industry:Science
A term referring to the closely spaced groups of lines observed in the spectra of the lightest elements, notably hydrogen and helium. The components of any one such group are characterized by identical values of the principal quantum number <i>n,</i> but different values of the azimuthal quantum number <i>l</i> and the angular momentum quantum number <i>j</i>.
Industry:Science
