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Le tapis de Sierpinski -itération 2-
No full textThe Sierpinski carpet -iteration 2- (Le tapis de Sierpinski -itération 2-
L'éponge de Menger -itération 5-
No full textThe Menger sponge -iteration 5- (L'éponge de Menger -itération 5-
Les 64 premières lignes du triangle de Pascal
No full textThe 64 first lines of the Pascal's Triangle (Les 64 premières lignes du triangle de Pascal
Un attracteur de Lorenz fractal
No full textA fractal Lorenz attractor (Un attracteur de Lorenz fractal
Fourth order energy-preserving localy implicit discretization for linear wave equations
No full textInternational audienc
Mécanisme de croissance et propriétés physiques de couches minces à base de composés analogues du bleu de Prusse
No full textIn this work, we have investigated the nucleation and growth mechanisms and also the physicochemical properties of Prussian blue analogues (PBA) thin films of general formula of AxM[M'(CN)6]y.zH2O, where A is an alkali metal ion, and M and M' are divalent and trivalent transition cations. RbNiCr and RbCoFe films are grown from a solution containing all precursors on a well-defined functionalized Si(111) surface terminated by a densely packed monolayer terminated with pyridyl groups. A thickness dependent study, using X-ray reflectivity and AFM characterizations, demonstrates that the nucleation is instantaneous and that initial islands expand laterally until coalescence. Above a thickness of ca. 15 nm, the films are quasi continuous and grains grow in a layer by layer fashion. X-ray diffraction demonstrates that the columnar grains are crystalline from bottom to top and adopt the (002) orientation, with, however no in plane orientation. In the case of RbNiCr, a uniform composition Rb0.1Ni[Cr(CN)6]0.7.zH2O (measured by Rutherford Backscattering) is determined, which is consistent with that of corresponding colloidal nanoparticles. In the case of RbCoFe, an excess of Rb is found with respect to the particles of the same material. The magnetic characterization of RbNiCr layers (SQUID measurements) give a magnetic moment of 3.9 μB, in agreement with expectation. The Curie temperature increases from 30 K to 65 K with increasing film thickness. Tilted magnetization anisotropy is observed induced by the film texture and also by the columnar structure of grains which aspect ratio height / diameter is greater than unity. RbCoFe layers exhibit photo switching properties (XAS measurements at Co K edge) indicating the presence of a significant fraction of Co(III)-Fe(II) pairs (66 %). A preliminary study of heterostructures RbNiCr/RbCoFe is also presented.Dans ce travail, nous avons étudié la nucléation, les mécanismes de croissance et les propriétés physico-chimiques de films minces de composés analogues du bleu de Prusse (PBA), de formule générale AxM[M'(CN)6]y.zH2O, où A est un cation alcalin, et M et M' sont des cations divalents et trivalents de métaux de transition. La croissance de films RbNiCr et RbCoFe a été réalisée à partir de solutions contenant tous les précurseurs, sur des surfaces de silicium Si(111) fonctionnalisées par une monocouche dense de groupements pyridyles. Des études en fonction de l'épaisseur des films ont été réalisées à partir de mesures de réflectivité de RX et de caractérisations par AFM. Ces études démontrent que la nucléation est instantanée et que les îlots initialement formés croissent latéralement jusqu'à coalescence. Au-delà d'une épaisseur de 15 nm, les films sont quasi continus et la croissance se poursuit couche par couche. Des mesures de diffraction des rayons X montrent que les grains sont colonnaires et cristallins sur toute l'épaisseur des films avec une texture (002), et sans orientation particulière dans le plan. Pour les films RbNiCr, une composition uniforme Rb0.1Ni[Cr(CN)6]0.7.zH2O, similaire à celle de nanoparticules colloïdales, a été déterminées à partir de mesures par rétrodiffusion Rutherford. Dans le cas des films RbCoFe, les mesures RBS ont montré l'existence d'un excès de Rb par rapport à la composition des nanoparticules. Les mesures des propriétés magnétiques des couches RbNiCr par magnétométrie SQUID donne un moment magnétique de 3,9 μB, en accord avec la valeur théorique, et indiquent une augmentation de la température de Curie de 30 K à 65 K lorsque l'épaisseur des films augmente de 2.7 nm à 46.4nm. Une anisotropie d'aimantation inclinée est observée qui resulte de la texture du film et de la structure colonnaire des grains dont le rapport d'aspect hauteur / diamètre est supérieur à l'unité. Les couches RbCoFe présentent des propriétés de photocommutation (mesures XAS au seuil K du Co) qui indiquent la présence d'une fraction importante (66%) de paires Co(II) / Fe(III). Une étude préliminaire d'hétérostructures RbNiCr / RbCoFe est également présentée
Kinetic Data on the Synergetic Role of Amines and Water in the Reduction of Phosphine-Ligated Palladium(II) to Palladium(0)
No full textInternational audienceTertiary amines such as EtN(iPr)2 do not reduce [PdCl2(PPh3)2] into a Pd0 complex. The latter is formed only after the addition of water (generation of HO-), as was reported by Grushin and Alper for NEt3. The mechanism of the PdII/Pd0 reduction performed in the presence of an excess amount of PPh3 is established quantitatively by means of electrochemical techniques that provide kinetic data (determination of the equilibrium and rate constants) for the disappearance of [PdCl2(PPh3)2] and the formation of [Pd0(PPh3)3]. [PdCl(OH)(PPh3)2] is formed, which allows reductive elimination between OH and the ligated PPh3 (zero-order reaction for PPh3), and this leads to a Pd0 complex. The reducing agent is ligated PPh3, which ultimately yields (O)PPh3. The rate of the overall reduction process is controlled by the amount of water that imposes the concentration of HO-
Search for neutral MSSM Higgs bosons decaying to a pair of tau leptons in pp collisions
No full textSubmitted to JHEP, see paper for full list of authorsA search for neutral Higgs bosons in the minimal supersymmetric extension of the standard model (MSSM) decaying to tau-lepton pairs in pp collisions is performed, using events recorded by the CMS experiment at the LHC. The dataset corresponds to an integrated luminosity of 24.6 inverse femtobarns, with 4.9 inverse femtobarns at 7 TeV and 19.7 inverse femtobarns at 8 TeV. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes the case where the Higgs boson is produced in association with a b-quark jet. No excess is observed in the tau-lepton-pair invariant mass spectrum. Exclusion limits are presented in the MSSM parameter space for different benchmark scenarios, m[h,max}, m[h,mod+], m[h,mod-], light-stop, light-stau, tau-phobic, and low-m[H]. Upper limits on the cross section times branching fraction for gluon fusion and b-quark associated Higgs boson production are also given
An Intensional Concurrent Faithful Encoding of Turing Machines
No full textInternational audienceThe benchmark for computation is typically given as Turing computability; the ability for a computation to be performed by a Turing Machine. Many languages exploit (indirect) encodings of Turing Machines to demonstrate their ability to support arbitrary computation. However, these encodings are usually by simulating the entire Turing Machine within the language, or by encoding a language that does an encoding or simulation itself. This second category is typical for process calculi that show an encoding of lambda-calculus (often with restrictions) that in turn simulates a Turing Machine. Such approaches lead to indirect encodings of Turing Machines that are complex, unclear, and only weakly equivalent after computation. This paper presents an approach to encoding Turing Machines into intensional process calculi that is faithful, reduction preserving, and structurally equivalent. The encoding is demonstrated in a simple asymmetric concurrent pattern calculus before generalised to simplify infinite terms, and to show encodings into Concurrent Pattern Calculus and Psi Calculi
Modeling the transport of drugs eluted from stents: physical phenomena driving drug distribution in the arterial wall
No full textInternational audienceDespite recent data that suggest that the overall performance of drug-eluting stents (DES) is superior to that of bare-metal stents, the long-term safety and efficacy of DES remain controversial. The risk of late stent thrombosis associated with the use of DES has also motivated the development of a new and promising treatment option in recent years, namely drug-coated balloons (DCB). Contrary to DES where the drug of choice is typically sirolimus and its derivatives, DCB use paclitaxel since the use of sirolimus does not appear to lead to satisfactory results. Since both sirolimus and paclitaxel are highly lipophilic drugs with similar transport properties, the reason for the success of paclitaxel but not sirolimus in DCB remains unclear. Computational models of the transport of drugs eluted from DES or DCB within the arterial wall promise to enhance our understanding of the performance of these devices. The present study develops a computational model of the transport of the two drugs paclitaxel and sirolimus eluted from DES in the arterial wall. The model takes into account the multilayered structure of the arterial wall and incorporates a reversible binding model to describe drug interactions with the constituents of the arterial wall. The present results demonstrate that the transport of paclitaxel in the arterial wall is dominated by convection while the transport of sirolimus is dominated by the binding process. These marked differences suggest that drug release kinetics of DES should be tailored to the type of drug used