How to stop a biological clock: Point of singularity

Abstract

Many processes in organisms proceed rhythmically. There are, for instance, daily rhythms as adaptations to the 24 hour time structure of the environment, annual rhythms as adaptations to the course of the year, but also shorter rhythms without any correlate to the environment such as the heart beat and respiration. Such rhythms can be stopped by a disturbance by e.g a light pulse given at a certain time point of an oscillation with a special strength. Models show, that the underlying oscillator is brought from a limit cycle into a singular point. Examples for daily rhythms, for an annual rhythm, and for the heart beat are presented, in which the rhythm is stopped. How this property can be used in the praxis is demonstrated by the case of the sudden heart-circulation collaps and in the photoperiodic flower induction of a plant.