Glossary

Acrophase Phase angle corresponding to the maximal value of the rhythmic parameter studied Circadian Period of oscillation is 24 ± 4 hours Cosinor-analysis Nonlinear regression procedure (applying a parameterised cosinus equation to the raw data series) Degree of Functional Coupling Percentage of the circadian component and harmonic ultradian components in relation to all significant rhythmic components of a spectrum based on the respective relative parts of their assigned variance Harmonic periods Period lengths are integer dividers of 24 h Harmonic portion Percentage of the number of the circadian and their harmonic ultradian components in relation to the number of all significant periods smaller or equal to the circadian rhythm Infradian Period length of oscillation is more than 28 hours MESOR Mean of oscillation of cosinor analysis Motility Swimming velocity in video-pixels per second Number of turns Number of changes of the direction per second Phase-shift Displacement of an oscillation along the time axis Polar Plots Graphical presentation of amplitude and acrophase Power spectral analysis Fourier transformed autocorrelation function for quantification of the harmonic frequency structure of activity rhythms Ultradian Period length of oscillation is less than 20 hours Zeitgeber (time trigger ) Forcing oscillation which entrains a biological rhythm