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In continued darkness following a standard pretreatment of 12 hours light and 12 hours dark, the stomata of Tradescantia virginiana did not reveal a truly repeating rhythm, but only a single opening cycle which matched the opening phase of the rhythm in light. An investigation of the phase response of this dark opening cycle to light and dark treatments revealed that the phase of the dark opening cycle could be manipulated as follows. When light commenced during that phase characteristic of darkness in nature, the dark opening cycle showed phase-shift, but little or no phase-shift occurred when light commenced during that phase characteristic of light in nature. The fact that the rhythms can be manipulated in this manner may indicate the plant's ability to adapt to different day lengths. [ABSTRACT FROM AUTHOR]

The goal of this study was to develop an objective quantitative method for representing the temporal organization of sleep in terms of the period and rhythmicity of REM sleep occurrences. Data on normative human sleep, already scored for stage REM and not stage REM, were subjected to a "binary autocorrelation." The mean period over 92 nights of sleep for 10 Ss was 101.5 rain and quite stable. Data is also presented on variability of the rhythm in terms of an "index of rhythmicity." Measures of temporal organization may prove to be as significant for sleep research as amount of the various sleep stages. [ABSTRACT FROM AUTHOR]

Studies the effect of training on rhythmic ability and other problems related to rhythm among the crippled children in Chicago, Illinois. Educational activities of the children; Motor phase of the educational program for convalescent crippled children; Test of ability to reproduce rhythm pattern.

Previous studies have shown large variations in basal heart rate (HR) in individuals over occasions. To examine long-term variability, one individual's HR was recorded daily for one year. Besides changes due to ambient temperature and periods of illness, obvious regular variations corresponded to day of week. Weekends and Mondays differed from the other four weekdays: HR was high on Saturdays and Mondays, and reached a nadir on Sundays. These fluctuations probably reflect the cultural pattern of activity over the week, rather than representing an intrinsic circaseptan rhythm. [ABSTRACT FROM AUTHOR]