External signals and internal oscillation dynamics:
Coding and amplification of coherent and noisy signals
Kaiser, F.
Institute of Applied Physics, Nonlinear Dynamics, University of Technology,
D-64289 Darmstadt, Germany
Only few areas of research are as controversal, both scientifically and politically, as research into the biological effects of electromagnetic fields. Experimental evidence for possible effects of weak static and time-varying fields is increasing, though the existence of effects is not necessarily related to health risks. Nonthermal effects, i.e. sub-kT energy effects, are widely accepted from both, experimental facts and theoretical considerations [1]. The specific effects can be described on hypothesis-based models for proposed mechanisms within the existing paradigms of physics and chemistry.
Nonlinear oscillatory processes are discussed under the influence of external signals to improve the theoretical understanding of signal interaction with and within biological systems. Concepts of nonlinear dynamics offer the tools to describe frequency specific responses of biological rhythms. These endogeneous rhythms exhibit stable periodic oscillations, they are represented by limit cycles (self-sustained oscillations) as specific solutions of the nonlinear models. The signals are either of electromagnetic or chemical/hormonal origin. Main emphasis is on the combined influence of very slow and very fast stimuli compared to the relevant frequencies and on the additional effects caused by external and internal noise. The models include biological signalling processes, primary physical interactions, intracellular chemical kinetics, secondary biological mechanisms and changes. Frequency encoding and decoding mechanisms are discussed within a paradigmatic model of coupled passive and active oscillators as well as signal amplification (stochastic resonance) by the combined influence of coherent and noisy stimuli.
[1] F. Kaiser, Bioelectrochem. Bioenerg. 41, 3-18, 1996.
| LOCATION |
DATE |
TIME |
| Lecture Hall II |
Thursday, April 9 |
08:55 am |