by Keyword: cooperation
Zhang, KX, Klingner, A, Le Gars, Y, Misra, S, Magdanz, V, Khalil, ISM, (2023). Locomotion of bovine spermatozoa during the transition from individual cells to bundles Proceedings Of The National Academy Of Sciences Of The United States Of America 120, e2211911120 
Various locomotion strategies employed by microorganisms are observed in complex biological environments. Spermatozoa assemble into bundles to improve their swimming efficiency compared to individual cells. However, the dynamic mechanisms for the formation of sperm bundles have not been fully characterized. In this study, we numerically and experimentally investigate the locomotion of spermatozoa during the transition from individual cells to bundles of two cells. Three consecutive dynamic behaviors are found across the course of the transition: hydrodynamic attraction/repulsion, alignment, and synchronization. The hydrodynamic attraction/repulsion depends on the relative orientation and distance between spermatozoa as well as their flagellar wave patterns and phase shift. Once the heads are attached, we find a stable equilibrium of the rotational hydrodynamics resulting in the alignment of the heads. The synchronization results from the combined influence of hydrodynamic and mechanical cell-to-cell interactions. Additionally, we find that the flagellar beat is regulated by the interactions during the bundle formation, whereby spermatozoa can synchronize their beats to enhance their swimming velocity.
JTD Keywords: behavior, cilia, collective locomotion, collective motion, competition, flagellar propulsion, hydrodynamics, motility, propulsion, sperm cooperation, tracking, Collective locomotion, Flagellar propulsion, Flagellar synchronization, Spermatozoa bundle
Soler, PMI, Hidalgo, C, Fekete, Z, Zalanyi, L, Khalil, ISM, Yeste, M, Magdanz, V, (2022). Bundle formation of sperm: Influence of environmental factors Frontiers In Endocrinology 13, 957684
Cooperative behaviour of sperm is one of the mechanisms that plays a role in sperm competition. It has been observed in several species that spermatozoa interact with each other to form agglomerates or bundles. In this study, we investigate the effect of physical and biochemical factors that will most likely promote bundle formation in bull sperm. These factors include fluid viscosity, swim-up process, post-thaw incubation time and media additives which promote capacitation. While viscosity does not seem to influence the degree of sperm bundling, swim-up, post-thaw migration time and suppressed capacitation increase the occurrence of sperm bundles. This leads to the conclusion that sperm bundling is a result of hydrodynamic and adhesive interactions between the cells which occurs frequently during prolonged incubation times.Copyright © 2022 Morcillo i Soler, Hidalgo, Fekete, Zalanyi, Khalil, Yeste and Magdanz.
JTD Keywords: acrosome reaction, adhesion, bundling, capacitation, cell-cell interaction, cooperation, cooperative behaviour, fertilization, mammals, membrane, motility, progesterone, sperm competition, sperm migration, sperm selection, Bovine spermatozoa, Bundling, Cell-cell interaction, Cooperative behaviour, Sperm competition, Sperm migration, Sperm selection, Spermatozoa
Hernansanz, A., Casals, A., Amat, J., (2015). A multi-robot cooperation strategy for dexterous task oriented teleoperation 
Robotics and Autonomous Systems , 68, 156-172
The use of multiple robots working cooperatively in a redundant way offers new possibilities in the execution of complex tasks in dynamic workspaces. The aim of this work is to increase the range of applicability of teleoperated systems by means of the automatic cooperation of multiple slave robots which, controlled by a human operator, act as if they were a unique robot: a Multi-Robot Cooperation Platform for Task-Oriented Teleoperation, MRCP. From the human operator commands, this robotic platform, the MRCP, dynamically selects the most suitable slave robot and manages, when necessary, a task transfer from one robot to another in order to achieve a smooth execution of teleoperated tasks. The result of the proposed methodology is an improved teleoperated system in terms of reachable workspace (volume, manoeuvrability and accessibility) and dexterity, thus widening its range of applicability. This approach allows human operators to focus their attention on the ongoing task more than on the teleoperated robots.
JTD Keywords: Multi-robot cooperation, Single-operator-multiple-robot, Task-oriented teleoperation
