October 2nd – PhyLife talk by Lars Folke Olsen

 Lars Folke Olsen will give the next PhyLife talk on 2nd of October in Lykeion at 11:00 am. Please find the title and abstract for the talk below.

 Title: Chaos in the Peroxidase-Oxidase oscillator: the DOP model revisited.

 Abstract: The conference “From nonlinear dynamical systems theory to observational chaos” to be held in Toulouse on October 9-11, 2023, is a tribute to prof. Otto E. Rössler, University of Tübingen, on the occasion of his 80th birthday in 2020. The conference has been postponed till now because of the Covid-19 epidemics. Otto Rössler is one of the pioneers in the development of chaos theory in the mid 1970ies. At the conference former students and colleagues will present work on chaotic behavior extending from the first observations of non-periodic “strange attractors” in computer simulations – which most physicists in those days rejected as “computer artefacts” – to modern applications of nonlinear dynamics and chaos in theory and practice.

In my lecture I will present both historical and current results of my work on complex behavior and chaos, starting with my first visit to Otto’s lab in Tübingen in 1976 as a graduate student, where I learned about chaos for the first time. Inspired by this I published the first experimental observation of chaos in 1977 together with my supervisor, prof. H. Degn. The system studied was an enzyme-catalyzed reaction – the so-called peroxidase-oxidase (PO) reaction in an open system. Today the PO reaction has status as a prototype reaction for complex dynamic behaviors in biological systems. In addition, I will present recent studies of a simple four-variable model of the PO reaction, the Degn-Olsen-Perram (DOP) model, using recently developed methods from complex systems theory. The studies reveal that this simple model has an astonishing richness of complex dynamic behaviors, and it can reproduce all previous experimental observations of complex behavior in the PO reaction. Furthermore, the model may serve as a template for studies of many other complex biological systems.