Collective functionality in active fluids:
 Hydrodynamic communication, bacterial active carpets, and ciliary mucus clearance Arnold JTM Mathijssen Stanford University, Dept. of Bioengineering, 443 Via Ortega, Stanford, California, USA amath@stanford.edu The vast majority of life forms make grand achievements through co-operative efforts, by assembling in dense schools, herds, charms, flocks, teams & parliaments, despite the depletion of resources in these crowded and dynamic environments. Such trade-offs occur not only at the organismic scale, but also between individual cells, and even among the molecular motors that constitute these. Here, we will explore some of the biophysical mechanisms that enable this multi-scale organisation. I will first focus on reliable communication in ultra-fast biology, […]