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Department of Mathematical Sciences

Seminar Archives

On this page you can find information about seminars in this and previous academic years, where available on the database.

Topological Solitons Seminar: Dynamical properties of Davydov solitons and biological applications

Presented by Larissa Brizhik, Bogolyubov Institute for Theoretical Physics (Kiev)

20 November 2007 14:15 in CM221

The influence of the external electromagnetic field on the dynamics of Davydov solitons in low-dimensional molecular systems is discussed. It is shown that there are resonant frequencies of the soliton response to the external field. One of these resonant frequencies results in the dissociation of the solitons, and the other one causes intensive absorption of the energy by the solitons from the external field and following intensive emission of sound waves in the molecular chain.

Propagation of a soliton in the molecular chain is affected by the periodic Peierls-Nabarro barrier, which results in the appearance of the oscillating component of soliton motion. As a result, solitons, which carrier charge (polarons), emit electromagnetic radiation of the characteristic frequency and its overtones. Energy dissipation via vibrational subsystem leads to the ratchet effect in the soliton dynamics, i.e., to the drift of the solitons in the periodic unbiased force. In symmetric molecular chains the ratchet effect takes place when the ac force is asymmetric in time. In asymmetric chains this effect occurs even in the harmonic external field.

Such dynamical properties of Davydov solitons should be manifested in the biological effects of external EMR on the charge transport during metabolism. In particular, this can constitute one of the mechanisms of nonthermal bioeffects of the millimeter wavelength radiation and a source of the endogenous electromagnetic field. The ractchet-type dynamics of solitons makes them to be good candidates to explain functioning of biomotors and to be perspective for nanotechnologies.

Contact p.m.sutcliffe@durham.ac.uk for more information