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DY: Fachverband Dynamik und Statistische Physik

DY 23: Finite size effects at phase transitions III (session accompanying the symposium of the same name)

DY 23.2: Vortrag

Mittwoch, 28. März 2007, 16:00–16:15, H3

Phase transition in optimal foraging of bats — •Magnus Jungsbluth and Alexander K. Hartmann — Institut für Theoretische Physik, Georg-August-Universität Göttingen

Phase transitions have been found in many combinatorial optimization problems. The phase transitions can be analyzed using statistical mechanics methods like finite-size scaling. We study the so-called optimal foraging problem, which arises in biology. The aim is to find optimal ways how animals find their food. In collaboration with the biologists group of York Winter (Bielefeld) we got extensive data for a system of bats that eat nectar from flowers. We introduce a model for the biological system and solve it with a genetic algorithm. We observe a phase transition when varying the amount of nectar each bat has to collect per night. Using finite-size scaling we obtain a critical exponent for the correlation length ν = 1.7(3) similar to the traveling salesman problem. Other results include the emergence of two different length scales when looking at clustered resources and flight-time distributions that match with those measured in nature.