Carlo Manzo is co-organising the AnDi Challenge, a scientific challenge to solve the problem of the anomalous diffusion of particles based on simple trajectories

The coordinator of the Quantitative Biolmaging research group (QuBi Lab) at UVic-UCC, Carlo Manzo, is organising the AnDi Challenge with members of other European universities and research centres. This scientific challenge is aimed at other researchers, and aims to bring the scientific community together to work on solving a problem for which no single consensus-based solution has been found, although various methods and theories have been developed over the years: the anomalous diffusion of simple trajectories.

In addition to Manzo, Gorka Muñoz-Gil and Maciej Lewenstein of the Institute of Photonic Sciences (ICFO) and Giovanni Volpe of the Soft Matter Lab research group at the University of Gothenburg (Sweden), Miguel A. Garcia-March from the Polytechnic University of Valencia and Ralf Metzler, coordinator of the Theoretical Physics research group at the University of Potsdam (Germany) are also involved in organising this challenge. Anyone wishing to participate can send the results of their analysis to the initiative's website, where they will be automatically qualified and classified, until 1 November 2020. The most significant results will be presented in a workshop which will be held in Castelldefels from 17 to 20 February 2021.

The anomalous diffusion of particles dates back to Robert Brown's observation of the erratic movement of pollen grains in 1827, and for which the theoretical foundations were provided by Albert Einstein eighty years later. Several deviations from Brownian motion have been discovered in animated and inanimate systems since then, in areas ranging from biology to the stock market. "Abnormal diffusion is related to non-equilibrium phenomena, flows of energy and information and transport in living systems," explains Manzo, who believes that "identifying the physical origin of this behaviour and calculating its properties is a crucial step towards understanding the nature of systems from the microscopic scale to the geological scale."

Several methods to quantify anomalous diffusion have been proposed in recent years, "but none has provided a comprehensive solution to the problem or a definitive data response," says Manzo. He says that "a simple analysis of studied trajectories usually provides limited information, especially if those trajectories are short, noisy, irregularly sampled or combine different behaviours." The challenge will therefore be to provide all the participants with the same data sets to enable an impartial assessment of all the published and unpublished methods to date, in order to characterise the anomalous diffusion of simple trajectories.