Network structure of vertebrate scavenger assemblages at the global scale: drivers and ecosystem functioning implications

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Final Moments II: Observational Properties and Physical Modeling of CSM-Interacting Type II Supernovae

International audienceWe present ultraviolet/optical/near-infrared observations and modeling of Type II supernovae (SNe II) whose early-time ($\delta t < 2$ days) spectra show transient, narrow emission lines from shock ionization of confined ($r < 10^{15}$ cm) circumstellar material (CSM). The observed electron-scattering broadened line profiles (i.e., IIn-like) of HI, He I/II, C III/IV, and N III/IV/V from the CSM persist on a characteristic timescale ($t_{\rm IIn}$) that marks a transition to a lower-density CSM and the emergence of Doppler-broadened features from the fast-moving SN ejecta. Our sample, the largest to date, consists of 39 SNe with early-time IIn-like features in addition to 35 "comparison" SNe with no evidence of early-time IIn-like features, all with ultraviolet observations. The total sample consists of 50 unpublished objects with 474 previously unpublished spectra and 50 multiband light curves, collected primarily through the Young Supernova Experiment and Global Supernova Project collaborations. For all sample objects, we find a significant correlation between peak ultraviolet brightness and both $t_{\rm IIn}$ and the rise time, as well as evidence for enhanced peak luminosities in SNe II with IIn-like features. We quantify mass-loss rates and CSM density for the sample through matching of peak multiband absolute magnitudes, rise times, $t_{\rm IIn}$ and optical SN spectra with a grid of radiation hydrodynamics and non-local thermodynamic equilibrium (nLTE) radiative-transfer simulations. For our grid of models, all with the same underlying explosion, there is a trend between the duration of the electron-scattering broadened line profiles and inferred mass-loss rate: $t_{\rm IIn} \approx 3.8[\dot{M}/(0.01 \textrm{M}_{\odot} \textrm{yr}^{-1})]$ days

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