An interactive fluid model of jellyfish for animation

We present an automatic animation system for jellyfish that is based on a physical simulation. We model the thrust of an adult jellyfish, and the organism's morphology in its most active mode of locomotion. We reduce our model by considering only species that are axially symmetric so that we can approximate the full 3D geometry of a jellyfish with a 2D simulation. We simulate the organism's elastic volume with a spring-mass system, and the surrounding sea water using the semi-Lagrangian method. We couple the two representations with the immersed boundary method. We propose a simple open-loop controller to contract the swimming muscles of the jellyfish. A 3D rendering model is extrapolated from our 2D simulation. We add variation to the extrapolated 3D geometry, which is inspired by empirical observations of real jellyfish. The resulting animation system is efficient with an acceptable compromise in physical accuracy

Perception and synthesis of biologically plausible motion: From human physiology to virtual reality

6th International Workshop on Gesture in Human-Computer Interaction and Simulation, Berder Isl, FRANCE, MAY 18-20, 2005International audienceTo model and simulate human gesture is a challenge which takes benefit from a close collaboration between scientists from several fields: psychology, physiology, biomechanics, cognitive and computer sciences, etc. As an a priori requirement, we need to better understand the so-called laws of biological motions, established all along the 20(th) century. When modelled and used to animate artificial creature, these laws makes these creatures (either virtual or robotic) move in a much more realistic, life-like, fashion

Global urban environmental change drives adaptation in white clover

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale