Mohammad Parhizkar receives Best Poster Award at SWARM 2019

The Ph.D. student Mohammad Parhizkar, supervised by Prof. Giovanna Di Marzo Serugendo (Collective Adaptive Systems group), has obtained the best poster award at SWARM 2019: The 3rd International Symposium on Swarm Behavior and Bio-Inspired Robotics, Okinawa, Japan on November 22nd, 2019.

Title: Self-organising Agent-Based Model to Study Stream-breaking Phenomenon During Aggregation Phase of Dictyostelium discoideum.
Authors: Mohammad Parhizkar, Jahn Nitschke, Louis Hellequin, Thierry Soldati, and Giovanna Di Marzo Serugendo
Abstract: Collective behavior in nature provides a source of inspiration to engineer artificial collective adaptive systems, due to their mechanisms favoring adaptation to environmental changes and enabling complex emergent behavior to arise from a relatively simple behavior of individual entities. As part of our ongoing research, we study the social amoeba Dictyostelium discoideum in order to derive agent-based models and mechanisms that we can then exploit in artificial systems. In this paper, we focus on the stream-breaking phenomenon occurring during the aggregation phase of the life cycle of D. discoideum. Stream-breaking is augmented and sustained by the capability of cells to relay the 3’, 5’-cyclic adenosine monophosphate (cAMP) signal to their local neighbors. We provide an agent-based model with three main elements explaining stream-breaking: (1) modeling of motive force and resistance of cells; (2) quorum sensing – for identifying threshold of concentration of cAMP below which cells start losing motive force, and for identifying threshold of counting factor (CF) above which the cell-intrinsic resistance increases because of the high number of cells at the back of the stream; (3) emergence of late centers further attracting cells. Results show that the breakup of aggregation streams depends on cell density, motility, and the concentration of cAMP and CF. The breakup also comes with the appearance of late centers. Our biological experiments, using Ax2(ka) strain, show similar behavior to our computational results. Further work will investigate the motive force during the slug formation phase of the D. discoideum life cycle and study the relationship with age, speed, and size of the slug.