Tendril perversion, often referred to in context as simply perversion, is a geometric phenomenon found in helicalstructures such as plant tendrils, in which a helical structure forms that is divided into two sections of opposite chirality, with a transition between the two in the middle.[1] A similar phenomenon can often be observed in kinked helical cables such as telephone handset cords.[2]
The phenomenon was known to Charles Darwin,[3] who wrote in 1865,
The term "tendril perversion" was coined by Goriely and Tabor in 1998 based on the word perversion found in the 19th Century science literature. "Perversion" is a transition from one chirality to another and was known to James Clerk Maxwell, who attributed it to the topologist J. B. Listing.[3][5]
Tendril perversion can be viewed as an example of spontaneous symmetry breaking, in which the strained structure of the tendril adopts a configuration of minimum energy while preserving zero overall twist.[1]
Tendril perversion has been studied both experimentally and theoretically. Gerbode et al. have made experimental studies of the coiling of cucumber tendrils.[6][7] A detailed study of a simple model of the physics of tendril perversion was made by MacMillen and Goriely in the early 2000s.[1] Liu et al. showed in 2014 that "the transition from a helical to a hemihelical shape, as well as the number of perversions, depends on the height to width ratio of the strip's cross-section."[2]
Generalized tendril perversions were put forward by Silva et al., to include perversions that can be intrinsically produced in elastic filaments, leading to a multiplicity of geometries and dynamical properties.[8]
https://en.wikipedia.org/wiki/Tendril_perversion
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