Dominant(redirected from dominant X-linked inheritance)
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(in architecture), the major element in the composition of an ensemble. It is usually a tall building, for example, the main building of Moscow State University on Lenin Hills in Moscow, or the vertical part of one of the buildings, such as the tower and spire of the Admiralty Building in Leningrad. Rising above the surrounding structures, the dominant marks the focal point in the spatial arrangement of the ensemble.
(in music), a harmonic function of a major or minor scale exhibiting a strong tendency toward the tonic. The fifth degree of the scale is the basis of the dominant chord and is itself called the dominant. Chords built on the seventh and third degrees of the scale also fulfill the function of a dominant. The tendency of dominant chords toward the tonic is related to the presence of the leading tone in the chords. The resolution of the dominant into the tonic establishes the tonality with greatest certainty. The tonality whose tonic is the basic dominant is called dominant.
in physiology, a focus of excitation in the central nervous system that temporarily determines the nature of the body’s response to external and internal stimulation.
The dominant nerve center (or group of centers) is highly excitable and capable of maintaining this elevated excitability for a long time—even after the initial stimulus is no longer active. While summing the relatively weak stimuli of other centers, the dominant simultaneously exerts an inhibitory effect on them. Under natural conditions the dominant is formed under the influence of reflex excitation or after certain hormones have acted on the nerve centers. A dominant can be created experimentally by applying a weak electric current or certain drugs directly to the nerve centers. The dominance of some nerve centers over others was first described by N. E. Vvedenskii in 1881.
In elucidating the mechanisms of formation of conditioned reflexes, I. P. Pavlov pointed out that the sustained elevation of excitability of various regions of the cerebral cortex largely determines the dynamics of higher nervous activity both in pathology and in health. A. A. Ukhtomskii formulated the main elements of the theory of the dominant as a general principle of function of nerve centers on the basis of experiments that he and his co-workers performed between 1911 and 1923. The function of a dominant is made apparent in the readiness of an organ to function and maintain its functional state. The dominant in the higher brain centers is the physiological basis of a number of mental phenomena, such as attention.
REFERENCESUkhtomskii, A. A. Dominanta. Moscow-Leningrad, 1966.
Mekhaniimy dominanty. Leningrad, 1967. (Symposium materials.)
N. G. ALEKSEEV and M. IU. UL’IANOV