| alternation of generations | The occurrence in one life history of two or more different forms differently produced, usually an alternation of a sexual with an asexual form. (09 Oct 1997) |
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| alternation | 1. The reciprocal succession of things in time or place; the act of following and being followed by turns; alternate succession, performance, or occurrence; as, the alternation of day and night, cold and heat, summer and winter, hope and fear. 2. <mathematics> Permutation. 3. The response of the congregation speaking alternately with the minister. Alternation of generation. See Generation. Origin: L. Alternatio: cf. F. Alternation. Source: Websters Dictionary (01 Mar 1998) |
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| cardiac alternation | The occurrence of any cardiac phenomenon every other beat. (05 Mar 2000) |
| mechanical alternation of the heart | A disorder in which contractions of the heart are regular but are alternately stronger and weaker. (05 Mar 2000) |
| concordant alternation | The alternation in either the mechanical or electrical activity of the heart, occurring in both systemic and pulmonary circulations. (05 Mar 2000) |
| discordant alternation | The alternation in cardiac activities of either the systemic or the pulmonary circulations, but not of both, or in both but oppositely directed in each. (05 Mar 2000) |
| electrical alternation of heart | A disorder in which the ventricular or atrial complexes or both are regular in time but of alternating pattern; detected by electrocardiography. The P, QRS, T, QRS-T, or P-QRST alternate singly or in combination. (05 Mar 2000) |