Physical Aging in Oscillatory and Excitable Systems

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The aim of our project is to investigate physical aging, memory and rejuvenation effects in classical oscillatory and excitable systems. So far such effects were studied in spin systems, spin glasses, polymer glasses and other materials in a large number of publications; they are still topical as a part of challenging out-of-equilibrium dynamics. Since the systems of our focus have a completely different range of applications in genetic, cellular, neural and ecological networks, our studies may open a new branch of research. The reason for our conjecture to find analogous aging processes in oscillatory and excitable systems is based on our previous results on the impact of frustration, disorder and noise, the occurrence of multistability, of slow relaxations and coarse-grained patterns in these systems; all these are typical ingredients in aging spin systems, particularly in spin glasses. Therefore we shall search primarily for manifestations of aging in prototypical systems of oscillators and excitable units with and without disorder and frustration. Along with the identification of aging and dynamical scaling behavior goes the search for universality classes, in particular the comparison with known dynamical scaling behavior from spin glasses and other materials. Originally the very fact to find universal scaling laws in spin systems and materials out-of-equilibrium came as a surprise; now an extension of these universality classes towards an inclusion of systems with very different microscopic dynamics would be not less amazing as well as the discovery of new universality classes. Currently it is an open question whether at all, and if so, which common underlying microscopic mechanisms exist behind the various phenomena: physical aging in spin systems and materials, physical aging in simple models of biological systems, which are in the focus of this project, and complex multi-level biological systems alive. Since the envisaged oscillatory and excitable systems are microscopically very distinct from formerly considered systems, we assume that this project can contribute to uncover these mechanisms.