Dans cette rubrique sont regroupées quelques faits marquants qui se sont déroulés dernièrement au laboratoire (séminaires, publications importantes, parution de livres, colloques...).
Les archives sont également accessibles ici .
A video produced by The Lutetium Project, an outreach YouTube channel co-founded by Mathias Kasiulis, a PhD student at LPTMC, just won the 2017 edition of the Milton Van Dyke Award. This prize is awarded every year by the Division of Fluid Dynamics of the American Physical Society (APSDFD) during its annual meeting, to reward pictures and videos of current research in fluid dynamics.
The video itself displays an experiment that was carried out in the PMMH laboratory, at ESPCI, and was published in Physical Review Letters in early 2017. It shows a drop of a mixture of water and alcohol bursting into a myriad of smaller droplets when it is deposited onto a bath of sunflower oil. This bursting is a rather uncommon example of a hydrodynamical phenomenon caused by the interplay between evaporation and surface tension. The video itself is part of a larger collection called "Experiments in Music", a series of videos by The Lutetium Project that aims at showing the aesthetic value of research experiments, accompanying it with an original music composed by Julien Mazet, a student at Conservatoire National Supérieur de Musique et de Danse de la Ville de Paris.
You can find all the other videos by The Lutetium Project on their YouTube channel: https://www.youtube.com/TheLutetiumProject
G. Vaccario, C. Antoine, and J. Talbot
Phys. Rev. Lett. 115, 240601 – Published 9 December 2015
Although there are many theoretical studies of the mean first-passage time (MFPT), most neglect the diffusive heterogeneity of real systems. We present exact analytical expressions for the MFPT and residence times of a pointlike particle diffusing in a spherically symmetric d-dimensional heterogeneous system composed of two concentric media with different diffusion coefficients with an absorbing inner boundary (target) and a reflecting outer boundary. By varying the convention, e.g., Itō, Stratonovich, or isothermal, chosen to interpret the overdamped Langevin equation with multiplicative noise describing the diffusion process, we find different predictions and counterintuitive results for the residence time in the outer region and hence for the MFPT, while the residence time in the inner region is independent of the convention. This convention dependence of residence times and the MFPT could provide insights about the heterogeneous diffusion in a cell or in a tumor, or for animal and insect searches inside their home range.
F. Léonard and B. Delamotte
Phys. Rev. Lett. 115, 200601 – Published 10 November 2015
We present models where γ+ and γ−, the exponents of the susceptibility in the high- and low-temperature phases, are generically different. In these models, continuous symmetries are explicitly broken down by discrete anisotropies that are irrelevant in the renormalization-group sense. The Zq-invariant models are the simplest examples for two-component order parameters (N=2) and the model with icosahedral symmetry for N=3. We accurately compute γ+−γ− as well as the ratio ν/ν′ of the exponents of the two correlation lengths present for T<Tc.