Title: SOLITON AND RATCHET MOTIONS IN HELICES
Authors: A.V.Zolotaryuk (Bogolyubov Institute for Theoretical Physics, 252143 Kyiv, Ukraine; Department of Mathematical Modelling, Technical University of Denmark, DK-2800 Lyngby, Denmark), P.L.Christiansen (Department of Mathematical Modelling, Technical University of Denmark, DK-2800 Lyngby, Denmark), B.Nord\'{e}n (Department of Physical Chemistry, Chalmers University of Technology, S-412 96 Gothenburg, Sweden), A.V.Savin (Department of Mathematical Modelling, Technical University of Denmark, DK-2800 Lyngby, Denmark; State Institute for Problems of Physics and Technology, 119034 Moscow, The Russian Federation)

The most simple and straightforward generalization of the standard one-dimensional molecular chain with nearest-neighbour interactions to three dimensions is shown to be a helix backbone with three types of intermolecular interactions, the chain with secondary structure (e.g., $\alpha$-helix in biology). The set of coupled nonlinear field equations with respect to the longitudinal and transverse displacements of the chain molecules is derived and stable non-topological three-component soliton solutions are found numerically. These solutions describe supersonic pulses of longitudinal compression accompanied by a localized transverse bulge and a localized torsional stretching of the helix backbone. Asymmetry caused by helicity of the backbone is shown to rectify zero-mean oscillating or fluctuating motions on a simple experimental mechanical model.

Comments: Figs. 3, Refs. 19, Tabs. 0.