Jordi Piñero, Ricard Solé, Artemy Kolchinsky

Many molecular systems operate by harvesting and storing energy from their environments. However, the maintenance of a nonequilibrium state necessary to support energy harvesting itself carries thermodynamic costs. We consider the optimal tradeoff between costs and benefits of energy harvesting in a nonequilibrium steady state, for a system that may be in contact with a fluctuating environment. We find a universal bound on this tradeoff, which leads to closed-form expressions for optimal power output and optimal steady-state distributions for three physically meaningful regimes. Our results are illustrated using a model of a unicyclic network, which is inspired by the logic of biomolecular cycles.

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Klaus Jaffe

Classical laws of thermodynamics apply only for reversible processes. Most processes however are irreversible and occur in open systems. That is the case of synergy that emerges from synchronized reciprocal positive feedback loops between a network of diverse actors. For this process to proceed, compatible information from different sources synchronically coordinates the actions of the actors resulting in a nonlinear increase in the useful work or potential energy the system can manage. In contrast noise is produced when incompatible information is mixed. This synergy produced from the coordination of different agents achieves non-linear gains in free energy and in information (negentropy). Free energy can be estimated by proxies such as individual autonomy of an organism, emancipation from the environment, productivity, efficiency, capacity for flexibility, self-regulation, and self-control of behavior; whereas entropy, or the lack of it, is revealed by the degree of synchronized division of ever more specialized labor, structural complexity, information, and dissipation of energy. Empirical examples that provide quantitative data for these phenomena are presented. Results show that increases in free energy density are concomitant with decreases in entropy density. This may be a rule for synergistic processes in irreversible thermodynamics, which is consilient with the first and second laws of classical thermodynamics. Under this light, biological evolution is the task of self reproducing irreversible synergistic system to discover empirically (through natural and sexual selection) types of order that increase their free energy.

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