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3D Simulations of Spatially Dispersive Metals with a Finite Element Time Domain Method
No full textInternational audienceWe present recent advances in the development of a Finite Element Time Domain (Discontinuous Galerkin) solver for computational nanophotonics. Throughout this contribution a particular focus is put on metallic nano structures of sizes between 1 nm and 15 nm. Metal structures at these sizes are well known to show spatial dispersion which can be modeled by a nonlocal dispersion model for the electron gas. Taking such a nonlocal model into account leads to a hydrodynamic fluid equation for the free electrons in the metal. While Maxwell's equations describe the evolution of the electromagnetic fields, the additional fluid equation accounts for the material response and is strongly coupled to Maxwell's equations by means of a source current. Numerically speaking, the considered 3D finite element time domain method benefits from high-‐order polynomial solutions on very flexible unstructured tetrahedral meshes. Additionally, working in time domain gives access to broad band frequency solution within a single simulation run due to short pulses. Exploiting distributed memory parallelism eventually allows large computational domains and hence realistic nanophotonic setups. From an application point of view, we assess the performance of the numerical method on multiple nanophotonic scenarios like spherical dimer systems (simulation_mesh_dimer.png) and nanocubes simulation_mesh_nanocube.png). We emphasize the importance of highly accurate numerical schemes that guarantee a powerful resolution of surface effects, which is especially indispensable for plasmonic applications since most physics happen in the vicinity of the metal surface. Moreover, we evidently show the importance of high-‐order numerical methods including curvilinear tetrahedral meshes in order to properly approximate material interfaces if roundings are of concern
Le rôle de XPC dans l’invasion des cancers cutanés chez l’homme
No full textSquamous cell carcinoma (SCC) is the most frequent metastatic skin cancer. His etiology is linked to exposure to ultraviolet radiation (UVR). Xeroderma pigmentosum C (XP-C) is a genetic disorder characterized by a severe susceptibility to aggressive SCCs following minimal exposure to UVR. XP-C cells are deficient in nucleotide excision repair (NER) of UV-induced DNA lesions. XP-C dermal fibroblasts expresse a phenotype resembling that of stromal fibroblasts associated to cancer cells with accumulation of reactive oxygen species and over expression of matrix metalloproteinase 1 (MMP1). We explored the effects of XP-C fibroblasts on migration and invasion of SCC cells. In organotypic skin cultures, XP-C fibroblasts promote the invasion of SCC cells. Also, scratch healing of SCC cells is enhanced with culture supernatants of XP-C fibroblasts through a mitogenic effect connected to increased ratio of SCC cells in the G2-M phase of the cell cycle. We show that XP-C fibroblasts overexpress the hepatocyte growth factor/scatter factor (HGF/SF) and activate the c-Met receptor and the p38 and JNK pathways in SCC cells. Blockage of HGF inhibits c-Met, p38 and JNK activation and prevented invasiveness of SCC cells within dermal equivalents. Spheroid assays show that XP-C fibroblasts lead SCC invasions. Our data indicate for the first time that XP-C fibroblasts are responsible for the formation of a permissive microenvironment towards SCC cells proliferation and invasion. Therapies targeting XP-C fibroblasts may be considered as a way to control aggressive cancer in XP-C patients.Le cancer spinocellulaire (CSC) est le cancer de la peau le plus fréquent chez l’homme. Son étiologie est liée à l'exposition aux rayonnements ultraviolets (UV). Le xeroderma pigmentosum C (XP-C) est une maladie génétique caractérisée par l’absence de la protéine XPC entrainant une déficience dans la réparation des lésions dans l’ADN induites par les UV. La persistance de ces lésions chez ces patients entraine l’apparition précoce de CSC particulièrement agressifs. Les fibroblastes cutanés XP-C présentent un phénotype ressemblant à celui des fibroblastes associés aux cellules cancéreuses, suggérant un rôle promoteur dans le développement précoce des CSC XP-C. Nous avons étudié les effets des fibroblastes XP-C sur l’invasion de cellules de carcinomes. Dans des cultures organotypiques de peau, les fibroblastes XP-C favorisent l'invasion des cellules de CSC. De plus, ex vivo, la cicatrisation des cellules CSC est plus rapide en présence de surnageants de culture de fibroblastes XP-C et est due à un effet mitogénique des fibroblastes XP-C qui augmente la proportion des cellules de CSC dans la phase G2-M du cycle. Les fibroblastes XP-C surexpriment le facteur de croissance HGF qui active le récepteur c-Met et les voies de signalisation p38 et JNK dans les cellules de CSC. Le blocage de HGF entraîne l’inactivation de c-Met, p38 et JNK et bloque l'invasion des cellules CSC. De plus, nous montrons que les fibroblastes XP-C jouent un rôle de cellules « leader » dans l’invasion des CSC. Les fibroblastes XP-C créent un microenvironnement permissif à l'invasion des CSC. Des thérapies ciblant les fibroblastes XP-C pourraient permettre le contrôle de l’invasion des CSC chez les XP
Note sous l’arrêt de la 1ère chambre civile de la Cour de cassation du 30 juin 2016
No full textNote d'arrêt (affaire "Tapie"
Note sous les arrêts de la Cour d’appel de Paris des 15 mars et 10 mai 2016
No full textNote d'arrêt (principe de la contradiction et droit de l'arbitrage
Post-depositional evolution over a time scale of 1 million years of eastern Mediterranean organic-rich and organic-poor sediments: new insights on the debromination and layer-silicate markers
No full textInternational audienc
CAPTURE OF MAGNETIC NANOPARTICLES ON ORDERED MAGNETIZABLE ARRAYS: A PARAMETRIC STUDY
No full textInternational audienceThe present work is focused on experimental study of magnetic separation of magnetic nanoparticles of a size range of 20-100 nm on ordered arrays of nickel micro-pillars when a dilute suspension of nanoparticles (ferrofluid) flows through a flat narrow channel with micro-pillars spanning the channel width and magnetized by an external magnetic field oriented at different angles with respect to the main flow. In a typical experiment, a part of suspended nanoparticles is captured by micro-pillars forming deposits whose size and shape depend on the flow speed, magnetic field intensity, field orientation, etc., while the rest of the particles escape from the micro-pillar array if the applied magnetic field is not strong enough. On the contrary, a relatively strong magnetic field induces a phase separation of nanoparticles manifested by appearance of bulk needle-like aggregates extended along the field. Such particle aggregation enhances significantly the efficiency of particle capture described by the steady-state volume V of deposits and the parameter Lambda=ln(Phy_in /Phy_out), appearing in the filtration equation, where Phy_in and Phy_out are particle concentrations at the channel inlet and outlet, respectively. The effects of different dimensionless parameters governing the physics of nanoparticle capture (Mason number, dipolar coupling parameter, particle concentration, angle between the field and the flow, geometry – square or hexagonal arrays) are studied in details and the optimal set of parameters ensuring the maximum capture efficiency is found. A theoretical model based on the particle trajectory analysis is developed and confirms the main experimental findings on strongly decreasing capture efficiency as function of Mason number and dipolar coupling parameter
PhD Symposium at 13th International Conference on ICT in Education, Research, and Industrial Applications
No full textInternational audienceThis volume represents the proceedings of the PhD Symposium co-located with the 13 th International Conference on ICT in Education, Research, and Industrial Applications (ICTERI 2017), held in Kyiv, Ukraine, in May 2017. It comprises 10 contributed papers that were carefully peer-reviewed and selected from 14 submissions. The accepted papers present the tractable ideas and early results of PhD projects or other research aiming at receiving a PhD