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a minor earthquake
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



an involuntary trembling of the entire body or parts of it. Tremors are characteristically rhythmic and stereotypic; usually they have a narrow range, most often affecting the fingers, eyelids, tongue, lower jaw, and head. In healthy subjects, tremors may be caused by muscular strain, emotional excitement, or exposure to cold. Pathological tremors may be symptoms of chronic alcoholism, thyrotoxicosis, neurotic states, acute infections, and such diseases as parkinsonism. The symptom is treated by treating the primary disease.

Eye tremor is an involuntary rapid movement of the eyeball in relation to the optic axis; its frequency is from 20 to 150 Hz, and its amplitude, from 5 to 15 seconds of arc. Visual perception itself depends to a significant degree on eye tremor, which produces constant changes in the illuminance of certain photoreceptors—that is, the photoreceptors located at the variously illuminated points of the retinal periphery. An image whose projection on the retina remains completely stable for more than a few seconds ceases to be perceived by the visual centers of the brain.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A minor earthquake. Also known as earthquake tremor; earth tremor.
Involuntary, rhythmic trembling of voluntary muscles resulting from alternate contraction and relaxation of opposing muscle groups.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
A fifth question (#12), though slightly lower in the percentage reporting "a great deal" or more disability also assessed the impact of action tremor. While these five questions had the highest percentage of patients endorsing a significant degree of disability, elimination of any question resulted in decreased internal reliability.
These scores represent action tremor, which we hereafter refer to simply as tremor.
In this cohort of community-dwelling elderly men, although unadjusted analyses were marginally significant, we did not find a significant overall association between blood or bone lead exposure biomarkers and ratings of action tremor or occurrence of elevated tremor after adjustment for potential confounders.
The most prevalent of these tremor types, action tremor, occurs when the arm is extended or during voluntary movements such as writing or typing.
In conclusion, the evidence presented suggests that the VIM DBS is an important site for reducing action tremor and improving force control in PD.
In 1998, the Consensus Statement on Tremor issued by the Movement Disorder Society (MDS) classified the different tremor types observed in PD in 3 categories: type I, resting and action tremor with similar frequencies; type II, resting and action tremor with differing frequencies; and type III, pure action tremor.
Lead is a ubiquitous toxicant (Konat and Clausen 1974; Schroeder and Tipton 1968), and laboratory animals and humans exposed to high levels of either inorganic or organic forms of lead develop neurologic disorders in which action tremor is prominent (Booze et al.
At one month, item 20 and item 21 of the UPDRS (rest and action tremor) decreased from 2.9 [+ or -] 1.0 to 0.4 [+ or -] 1.0 (p < 0.001) and from 3.00 [+ or -] 1.2 to 0.6 [+ or -] 1.0, respectively, and, at 6 months, to 0.3 [+ or -] 0.5 and 0.6 [+ or -] 1.1, respectively.
Postural and action tremors were found in both hands, although there was no tremor involving the lower limbs or voice.
* Action tremors -- They happen when you move deliberately.
Tremors are classified as rest or action tremors, with the latter being further categorized as postural (occurring while the patient maintains a position against gravity) or kinetic (occurring during voluntary movement).