- 行业: Printing & publishing
- Number of terms: 178089
- Number of blossaries: 0
- Company Profile:
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 study of celestial bodies by examination of the energy they emit at radio frequencies. Celestial radio noise originates by one of several processes. These include both broadband continuum radiation owing to (1) thermal radiation from solid bodies such as the planets, (2) thermal or bremsstrahlung radiation from hot gas in the interstellar medium, (3) synchrotron radiation from ultrarelativistic electrons moving in weak magnetic fields, (4) coherent processes as found in the Sun and on Jupiter, and (5) pulsed radiation from the rapidly rotating neutron stars, as well as (6) narrow “spectral line” radiation from atomic or molecular transitions that occur in the interstellar medium or in the gaseous envelopes around stars.
Industry:Science
The path traced by the instantaneous center of a plane figure when it undergoes plane motion. If a plane rigid body is constrained to move in its own plane but is otherwise free to undergo an arbitrary translational and rotational motion, it is found that at any instant there exists a point, called the instantaneous center, about which the body is rotating. The path that this instantaneous center traces out in space as the motion unfolds is called the space centrode. The path that it would trace out in a coordinate system which is rigidly attached to the body is called the body centrode. The motion may therefore be specified, when the two centrodes are given, by allowing one curve to roll without slipping along the other.
Industry:Science
The temperature at which liquid and solid water are in equilibrium under atmospheric pressure. The ice point is by far the most important “fixed point” for defining temperature scales and for calibrating thermometers. It is 273.15 K (0°C or 32°F). A closely related point is the triple point, where liquid, solid, and gaseous water are in equilibrium. It is 0.01 K (0.018°F) higher on the Kelvin scale than the ice point. The triple point has gained favor as the primary standard since it can be attained with great accuracy in a simple closed vessel, isolated from the atmosphere. Readings are reproducible to about 0.0001 K (0.0002°F), but dissolved gases or other foreign matter may raise the error to 0.001 K (0.002°F) or more.
Industry:Science
The second largest planet in the solar system and the sixth in order of distance to the Sun. The outermost planet known prior to 1781, Saturn is surrounded by a beautiful system of rings, more than 30 moons, and a complex magnetosphere. Despite the planet's huge size, its mean density is so low it could float in water. Saturn is also the only planet that has a satellite (Titan) with a dense atmosphere. This distant planetary system has been visited by four spacecraft: <i>Pioneer 11</i> in 1979, <i>Voyagers 1</i> and <i>2</i> in 1980–1981, and <i>Cassini-Huygens</i> since 2004. The first three were flybys; the last is a joint United States–European mission consisting of a Saturn orbiter and a probe into the atmosphere of Titan.
Industry:Science
The study of optical phenomena occurring in the atmosphere. Many light effects can be seen by looking skyward, and all of them, resulting from the interaction of light with the atmosphere, lie in the province of atmospheric optics or meteorological optics. The subject also includes the effect of light waves too long or too short to be detected by the human eye—light-type radiation in the infrared or ultraviolet regions of the spectrum. Light interacts with the different components of the atmosphere by a variety of physical processes, the most important being scattering, reflection, refraction, diffraction, absorption, and emission. Some other processes involving photochemistry and ionization are not considered in this article.
Industry:Science
The number of parts by weight of an element or compound which will combine with or replace, directly or indirectly, 1.008 parts by weight of hydrogen, 8.00 parts of oxygen, or the equilvalent weight of any other element or compound. The term equivalent weight comes from the law of equivalent proportions, which states that the weights of two elements A and B which combine separately with identical weights of another element C are either the weights in which A and B combine together, or are related to them in the ratio of small whole numbers. A standard weight of 8.000 parts is chosen for oxygen. For all elements, the atomic weight is equal to the equivalent weight times a small whole number, called the valence of the element.
Industry:Science
The origin and early evolutionary history of mollusks, one of the most diverse and fascinating groups of animals alive today, is traditionally based on the study of shells found in fossil deposits dating from the Early Cambrian, about 540 million years ago. Different hypotheses concerning the supposed morphology of the ancestral mollusk have emerged in the last 20 years, one preponderant view being that early forms were microscopic and possessed a simple mineralized shell. The restudy of a collection of half- billion-year-old fossils from the Burgess Shale (a fossil deposit featuring exceptionally preserved Middle Cambrian marine biota located in southern British Columbia) opens new insights concerning early molluscan evolution.
Industry:Science
The set of physical, mental, and functional abnormalities that result from trisomy 21, the presence in the genome of three, rather than the normal two, chromosomes 21. Down syndrome is one of the most frequent genetic causes of mental retardation. The physical abnormalities that together give rise to the distinctive facial appearance associated with this condition include upslanting eyes with epicanthic folds (folds of skin over the inner corners), flatness of the bridge of the nose and of the middle portion of the face, and a tendency to protrude the tongue, especially when very young. Many other minor, functionally inconsequential abnormalities of the ears, hands, and feet may also be present, and stature is generally reduced.
Industry:Science
The splitting, into two, of the potential function along the bending coordinate in degenerate electronic states of linear triatomic or polyatomic molecules. Most of the areas and methods of molecular physics and spectroscopy assume the validity of the Born-Oppenheimer approximation. The nuclei generally move much more slowly than the electrons, the frequencies associated with electronic transitions are much higher than vibrational frequencies, and one can consider separately the three types of molecular motion: electronic, vibrational, and rotational. These statements are no longer necessarily valid for electronic states which are degenerate or at least close to degeneracy, and the Born-Oppenheimer approximation breaks down.
Industry:Science
The logarithm (to the base 10) of the reciprocal of the equilibrium constant for a specified reaction under specified conditions (for example, solvent and temperature). p<i>K</i> values are often more convenient to tabulate and use than the equilibrium constants themselves. The value of <i>K</i> for the dissociation of the HSO<sub>4</sub><sup>-</sup> ion in aqueous solution at 77°F (25°C) is 0.0102 mole/liter. The logarithm is 0. 008<sub>6</sub> − 2 = −1.991<sub>4</sub>. p<i>K</i> is therefore +1.991<sub>4</sub>. The choice of algebraic sign, although arbitrary, results in positive values for most dissociation constants applicable to aqueous solutions. The concept of p<i>K</i> is especially valuable in the study of solutions.
Industry:Science
