- 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.
A violently rotating, tall, narrow column of air (that is, a vortex), typically about 300 ft (100 m) in diameter, that extends to the ground from a cumulonimbus cloud. The vast majority of tornadoes rotate cyclonically (counterclockwise in the Northern Hemisphere). Of all atmospheric storms, tornadoes are the most violent.
Industry:Science
A viral disease of European rabbits (<i>Oryctolagus</i>) and domestic rabbits, spread mainly by biting insects (mosquitoes and rabbit fleas) and characterized by edematous swellings of the skin, particularly on the head and anogenital area. The disease is caused by infection with myxoma virus, a pox virus, which occurs naturally in certain species of the genus <i>Sylvilagus</i> in North, Central, and South America. In these rabbits, infection results generally in localized, nonmalignant tumors that disappear in weeks or months.
Industry:Science
A viral disease of sheep, capable of producing central nervous system manifestations. It occurs chiefly in the British Isles. Infections have been reported, although rarely, among persons working with sheep.
Industry:Science
A viral family made up of the small (18–30 nanometers) ether-sensitive viruses that lack an envelope and have a ribonucleic acid (RNA) genome. The name is derived from “pico” meaning very small, and RNA for the nucleic acid type. Most of the picornaviruses are stabilized by magnesium chloride against thermal inactivation. The virion is made up of a nucleic acid core surrounded by a capsid of 32 subunits (capsomeres) arranged in the icosahedral form of cubic symmetry. Within the infected cell, virus particles are assembled in the cytoplasm, where they tend to aggregate in crystalline array.
Industry:Science
A viral infection that affects the digestive, intestinal, and respiratory tracts and the neurological system of birds. The causative agent is an enveloped ribonucleic acid (RNA) virus that is classified as a paramyxovirus.
Industry:Science
A virtual array of sources of sound in a fluid (more fully termed a parametric acoustic array) that is formed by two collinear acoustic waves propagating in the same direction, which interact because of the nonlinearity (parameter) of the fluid medium to generate new acoustic fields.
The array is virtual because it is formed in the fluid medium away from the devices responsible for the primary field components. If the primary interacting field is composed of two essentially monochromatic waves, with frequencies ν<sub>1</sub> and ν<sub>2</sub>, then the new fields will form at the sum and difference frequencies, ν<sub>1</sub> ± ν<sub>2</sub>. If ν<sub>1</sub> and ν<sub>2</sub> are slightly different, then the difference frequency, ν<sub>1</sub> − ν<sub>2</sub>, will be quite small. Since absorption of sound in fluids generally increases rapidly with frequency, this difference-frequency wave will outlast the primary- and sum-frequency waves. In addition to suffering less absorption and propagating further, the difference-frequency wave possesses two remarkable properties: most of its energy is concentrated in a narrow angular sector in the direction of propagation of the primary waves, and it has no sidelobes. Parametric arrays can be used for both directional transmission and directional reception of sound.
Industry:Science
A virus belonging to the Paramyxoviridae, genus <i>Pneumovirus</i>. This virus, although unrelated to any other known respiratory disease agent and differing from the parainfluenza viruses in a number of important characteristics, has been associated with a large proportion of respiratory illnesses in very young children, particularly bronchiolitis and pneumonia. It appears to be one of the major causes of these serious illnesses of infants. It is the only respiratory virus that occurs with its greatest frequency in infants in their first 6 months of life. In older infants and children, a milder illness is produced. Respiratory syncytial virus infection in adult volunteers gave rise to a coldlike illness; adult infection took place readily, even though the adults had moderate to high levels of antibody.
Industry:Science
A virus that by mutation has lost the ability to be replicated in the host cell without the aid of a helper virus. The virus particles (virions) contain all the viral structural components; they can attach, penetrate, and release their nucleic acid ribonucleic acid (RNA), deoxyribonucleic acid (DNA)) within the host cell.
However, since the mutation has destroyed an essential function, new virions will not be made unless the cell was simultaneously infected with the helper virus, which can provide the missing function. Only then will the cell produce a mixed population of new helper and defective viruses. Occasionally, when their nucleic acids become integrated in the DNA of the host cell, defective viruses persist in nature by propagation from mother cell to daughter cell.
Industry:Science
A volcanic glass, usually of rhyolitic composition, formed by rapid cooling of viscous lava. The color is jet-black because of abundant microscopic, embryonic crystal growths (crystallites) which make the glass opaque except on thin edges. Iron oxide dust may produce red or brown obsidian.
Industry:Science
A voltage amplifier intended for amplifying a low-level input signal. The output is the input to another amplifier with a higher input level. For example, if the second amplifier needs a 500-mV signal to produce the desired power output and one has a microphone with a maximum output of 10 mV, one would use a preamplifier with a gain of 50 to achieve the desired power output. The term preamplifier is not precise; it has been applied to the portion of an amplifier preceding the power output stage and is not an additional system component. The term can also apply to a radio-frequency amplifier to amplify weak signals. The output is the radio receiver input.
Industry:Science
