common

common

[kom-uhn]
cold, common, acute viral infection of the mucous membranes of the nose and throat, often involving the sinuses. The typical sore throat, sneezing, and fatigue may be accompanied by body aches, headache, low fever, and chills. The congested and discharging mucous membrane may become a fertile ground for a secondary bacterial invasion that can spread to the larynx, bronchi, lungs, or ears. Uncomplicated infections usually last from three to ten days.

The cold is the most common human ailment. Most adult Americans suffer from one to four colds per year, but children ages one to five—who are the most susceptible—typically may contract as many as eight. Colds are spread by respiratory droplets or by contaminated hands or objects. Although the incidence of colds is higher in winter, exposure to chilling or dampness is considered to be of little significance.

Any one of up to 200 viruses (such as the rhinoviruses, coronaviruses, or respiratory syncytial virus [RSV]) can cause colds, to which it seems almost no one is immune. Infection with a viral strain confers only temporary immunity to that strain. Colds in infants and young children caused by RSV can progress to pneumonia and other complications, especially in those under a year old who were born prematurely or have chronic lung disease; RSV causes an estimated 4,500 deaths yearly in these groups in the United States.

There is no treatment for the common cold other than that aimed at relieving symptoms and keeping the body well-rested, -fed, and -hydrated. Because of the growing problem of drug resistance, doctors are being discouraged from prescribing antibiotics (which do not affect viruses) for colds unless secondary bacterial infection makes them necessary. There is no convincing evidence that vitamin C megadoses can prevent the common cold.

Researchers have reported reduction or prevention of cold symptoms in human tests of an experimental drug against rhinoviruses, which cause nearly half of all colds. The drug acts by imitating a molecule in the body called ICAM-1, to which the rhinovirus attaches to produce colds. As rhinoviruses attach to the decoy molecules instead, the likelihood or severity of infection is decreased.

Marriage that is without a civil or religious ceremony and is based on the parties' agreement to consider themselves married and usually also on their cohabitation for a period of time. Most jurisdictions no longer allow this type of marriage to be formed, though they may recognize such marriages formed before a certain date or formed in a jurisdiction that permits such marriages.

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Nonmigratory, earless seal (Phoca vitulina) found throughout the Northern Hemisphere. Harbour seals are whitish or grayish at birth, generally gray with black spots as adults. The adult male may reach a length of about 6 ft (1.8 m) and a weight of almost 300 lb (130 kg); the female is somewhat smaller. Found along coastlines and in a few freshwater lakes in Canada and Alaska, the harbour seal is a gregarious animal that feeds on fish, squid, and crustaceans. It is of little economic value and in some areas is considered a nuisance by fishermen.

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Sage (Salvia officinalis)

Aromatic perennial herb (Salvia officinalis) of the mint family, native to the Mediterranean. Its leaves are used fresh or dried as a flavouring in many foods. The stems, 2 ft (60 cm) tall, have rough or wrinkled, downy, gray-green or whitish green oval leaves. The flowers may be purple, pink, white, or red. Since the Middle Ages, sage tea has been brewed as a spring tonic and a stimulant believed to strengthen the memory and promote wisdom. Seealso salvia.

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(born Aug. 4, 1816, Shenandoah, N.Y., U.S.—died July 22, 1906, Lawrence Beach, N.Y.) U.S. financier. He worked as an errand boy, studying arithmetic and bookkeeping in his spare time, and in 1839 he started a wholesale grocery business, which earned him enough money to start a Hudson River shipping trade. He served in Congress (1853–57). Sage invested successfully in the La Crosse Railroad in Wisconsin, and he eventually acquired an interest in more than 40 railroads, serving as director or president of 20. He helped organize the Atlantic & Pacific Telegraph Co. In 1872 he originated stock-market puts and calls (options to buy or sell a set amount of stock at a set price and within a given time limit), but he stopped dealing in them after losing $7 million in the panic of 1884. His wife, Margaret Olivia Sage, established the Russell Sage Foundation and Russell Sage College (Troy, N.Y.) after his death.

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(born Aug. 4, 1816, Shenandoah, N.Y., U.S.—died July 22, 1906, Lawrence Beach, N.Y.) U.S. financier. He worked as an errand boy, studying arithmetic and bookkeeping in his spare time, and in 1839 he started a wholesale grocery business, which earned him enough money to start a Hudson River shipping trade. He served in Congress (1853–57). Sage invested successfully in the La Crosse Railroad in Wisconsin, and he eventually acquired an interest in more than 40 railroads, serving as director or president of 20. He helped organize the Atlantic & Pacific Telegraph Co. In 1872 he originated stock-market puts and calls (options to buy or sell a set amount of stock at a set price and within a given time limit), but he stopped dealing in them after losing $7 million in the panic of 1884. His wife, Margaret Olivia Sage, established the Russell Sage Foundation and Russell Sage College (Troy, N.Y.) after his death.

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Body of law based on custom and general principles and that, embodied in case law, serves as precedent or is applied to situations not covered by statute. Under the common-law system, when a court decides and reports its decision concerning a particular case, the case becomes part of the body of law and can be used in later cases involving similar matters. This use of precedents is known as stare decisis. Common law has been administered in the courts of England since the Middle Ages; it is also found in the U.S. and in most of the British Commonwealth. It is distinguished from civil law.

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Viral infection of the upper and sometimes the lower respiratory tract. Symptoms, which are relatively mild, include sneezing, fatigue, sore throat, and stuffy or runny nose (but not fever); they usually last only a few days. About 200 different strains of virus can produce colds; they are spread by direct or indirect contact. The cold is the most common of all illnesses; the average person gets several every year. Incidence peaks in the fall. Treatment involves rest, adequate fluid intake, and over-the-counter remedies for the symptoms. Antibiotics do not combat the virus but may be given if secondary infections develop.

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Large European beetle (Melolontha melolontha) that damages foliage, flowers, and fruit as an adult and plant roots as a larva. In Britain, the name refers more broadly to any of the beetles in this subfamily (Melolonthinae), which are known in North America as June beetles. Seealso chafer, scarab beetle.

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Hardy, greenish brown fish (Cyprinus carpio, family Cyprinidae) native to Asia but introduced into Europe, North America, and elsewhere. Large-scaled, with two barbels (fleshy, whiskerlike feelers) on each side of its upper jaw, the carp lives alone or in small schools in quiet, weedy, mud-bottomed ponds, lakes, and rivers. An omnivore, it often stirs up sediment while rooting about for food, adversely affecting many plants and animals. Carp grow to an average length of about 14 in. (35 cm); some grow to 40 in. (100 cm) and 49 lbs (22 kg). In captivity they may live more than 40 years.

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In telecommunication, the term common-mode interference has the following meanings:

  1. Interference that appears on both signal leads (signal and circuit return), or the terminals of a measuring circuit, and ground.
  2. A form of coherent interference that affects two or more elements of a network in a similar manner (i.e., highly coupled) as distinct from locally generated noise or interference that is statistically independent between pairs of network elements.

Techniques for dealing with common-mode interference

Common mode noise may be isolated from the desired signal by various means:

  • Common mode noise may sensed and fed back negatively into object providing the signals (see Driven Right Leg).
  • Both signal and signal return may be applied to the primary of a transformer, with the signal taken from the secondary. As common mode interference will not cause current to be induced in the primary, no signal from this source will be seen in the secondary, while differential signals on the primary will cause current in the primary and so cause induced voltage in the secondary.
  • A signal transformer may have a center-tapped primary to ground, with the signal and signal return operating as a balanced line (push-pull technique). This is advantageous its resistance to signals raised on ground due to ground loop induction and ground circuit resistance.
  • The signal (line and return) may be used to drive the LED in an opto-isolator.

See also

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