pinecone/core-2020-05-10-deduplication huggingface dataset:
Regular poly(para-phenylene) films bound to gold surfaces through the electrochemical reduction of diazonium salts followed by electropolymerization in an ionic liquid

International audienceBy combining the electroreduction of diazonium salts and the electropolymerization of conducting polymers in an ionic liquid, the electrografting of a regular poly(para-phenylene) film on a gold substrate is achieved, leading to the strong and robust anchoring of the PPP polymers on the substrate (Au-PPP hybrid). A thin layer covalently bound to the substrate is first prepared by the reduction of benzenediazonium salt (BD), then, on top of this layer, a thicker layer of poly(para-phenylene) (PPP) is easily grown by the electrochemical oxidation of biphenyl in the [BMIm][PF6] ionic liquid. The resulting material is thoroughly characterized by IR, ToF-SIMS and fluorescence spectroscopies. The analyses show the formation of well regular PPP layers that are wired to the substrate. The key role of the [BMIm][PF6] ionic liquid in the structuration of the polymer is emphasized
Positivity-preserving schemes for Euler equations: Sharp and practical CFL conditions

International audienceWhen one solves PDEs modelling physical phenomena, it is of great importance to take physical constraints into account. More precisely, numerical schemes have to be designed such that discrete solutions satisfy the same constraints as exact solutions. For instance, the underlying physical assumptions for the Euler equations are the positivity of both den- sity and pressure variables. We consider in this paper an unstructured vertex-based tesselation in R2 . Given a MUSCL finite volume scheme and given a reconstruction method (including a limiting process), the point is to determine whether the overall scheme ensures the positivity. The present work is issued from seminal papers from Perthame and Shu (On positivity preserving finite volume schemes for Euler equations, Numer. Math. 73 (1996) 119-130) and Berthon (Robustness of MUSCL schemes for 2D unstructured meshes, J. Comput. Phys. 218 (2) (2006) 495-509). They proved in different frameworks that under assumptions on the cor- responding one-dimensional numerical flux, a suitable CFL condition guarantees that den- sity and pressure remain positive. We first analyse Berthon's method by presenting the ins and outs. We then propose a more general approach adding non geometric degrees of freedom. This approach includes an optimization procedure in order to make the CFL condition explicit and as less restric- tive as possible. The reconstruction method is handled independently by means of s- limiters and of an additional damping parameter. An algorithm is provided in order to specify the adjustments to make in a preexisting code based on a certain numerical flux. Numerical simulations are carried out to prove the accuracy of the method and its ability to deal with low densities and pressures
A complete set of line parameters for CH3Br in the 10-microns spectral region

International audienceUsing FT spectra (Bruker IFS 120, unapodized FWHM resolution ̴ 0.001 cmˉ¹) of methyl bromide CH3Br, absolute line positions and intensities, as well as self- and N2-broadening coefficients have been measured for about 1200 lines, between 880 and 1050 cmˉ¹, in the band of both 12CH379Br and 12CH381Br isotopologues. An absolute wavenumber calibration has been performed using the frequencies of the band of NH3. A multispectrum fitting procedure has been used to retrieve simultaneously the line parameters from 6 experimental spectra recorded at different pressures of CH3Br and N2. Average absolute accuracies of the measurements have been estimated to be equal to +/- 0.0002 cmˉ¹ for line positions, to +/- 5% for line intensities, and to +/- 5-10% for broadening coefficients. A theoretical treatment of measured line positions permitted a prediction of positions and assignments for the whole 10-µm spectral region. Measured line intensities have been analyzed in order to predict the intensities for the whole band. The J and K dependences of the self- and N2-broadening coefficients have been observed and modeled. These measurements improve the precision of wavenumbers and line intensities previously obtained and lead us, for the first time, to a complete set of self- and N2-broadening coefficients for which clear J- and K-dependences have been observed and modeled. A complete line list containing line positions, intensities, self- and N2-broadening coefficients has then been generated for atmospheric purposes from 820 to 1120 cmˉ¹
Monitoring volcanoes using seismic noise correlations Surveillance des volcans à partir du bruit de fond sismique

International audienceIn this article, we summarize some recent results of measurements of temporal changes of active volcanoes using seismic noise cross-correlations. We first present a novel approach to estimate volcano interior temporal seismic velocity changes. The proposed method allows to measure very small velocity changes (≈ 0.1%) with a time resolution as small as one day. The application of that method to Piton de la Fournaise Volcano (La Réunion Island) shows velocity decreases preceding eruptions. Moreover, velocity changes from noise cross-correlations over 10 years allow to detect transient velocity changes that could be due to long-lasting intrusions of magma without eruptive activity or to pressure buildup associated to the replenishing of the magma reservoir. We also present preliminary results of noise cross-correlation waveform perturbation associated with the occurrence of dike injection and volcanic eruption. We show that such an analysis leads us to locate the areas of dike injection and eruptive fissures at Piton de la Fournaise Volcano. These recent results suggest that monitoring volcanoes using seismic noise correlations should improve our ability to forecast eruptions, their intensity and thus potential environmental impact
Tuning the Mechanical Properties in Model Nanocomposites: Influence of the Polymer-Filler Interfacial Interactions

International audienceThis paper presents a study of the polymer-filler interfacial effects on filler dispersion and mechanical reinforcement in Polystyrene (PS) / silica nanocomposites by direct comparison of two model systems: un-grafted and PS-grafted silica dispersed in PS matrix. The structure of nanoparticles has been investigated by combining Small Angle Neutron Scattering (SANS) measurements and Transmission Electronic Microscopic (TEM) images. The mechanical properties were studied over a wide range of deformation by plate/plate rheology and uni-axial stretching. At low silica volume fraction, the particles arrange, for both systems, in small finite size non-connected aggregates and the materials exhibit a solid-like behavior independent of the local polymer/fillers interactions suggesting that reinforcement is dominated by additional long range effects. At high silica volume fraction, a continuous connected network is created leading to a fast increase of reinforcement whose amplitude is then directly dependent on the strength of the local particle/particle interactions and lower with grafting likely due to deformation of grafted polymer
A 40-year-old divided highway does not prevent gene flow in the alpine newt Ichthyosaura alpestris

International audienceRoads are of major concern in conservation biology, as they are known to restrict animal movements through landscape fragmentation, and may therefore impact genetic patterns in native terrestrial organisms. We assessed the effect of two large-scale transportation infrastructures (LTIs), a 40-year-old highway and a 30 year-old high-speed railway, on the spatial genetic structure of the alpine newt Ichthyosaura alpestris, a highly nomadic amphibian. Genetic data were gathered following a targeted individual-based sampling scheme and analysed using both overlay and correlative methods. While simulations suggested that the highway may be old enough for a significant barrier effect to be detected, LTIs were never detected as barriers to gene flow: inferred genetic boundaries rather coincided with transition zones between major landscape entities. Furthermore, spatial principal component analysis, a method designed to reveal cryptic genetic spatial patterns in high gene flow species, counter-intuitively suggested that the highway may act as a potential dispersal corridor in low-quality habitats, thus challenging traditional hypotheses on road impacts in amphibians. Our study showed that considering local interactions between species, infrastructures and landscape-specific characteristics is essential for better understanding the potential impacts of roads on movement patterns in terrestrial organisms
Quasi-geostrophic kinematic dynamos at low magnetic Prandtl number

International audienceRapidly rotating spherical kinematic dynamos at very low Ekman and Prandtl numbers are computed using the combination of a quasi-geostrophic (QG) model for the velocity field and a classical spectral 3D code for the magnetic field. The QG flow is computed in the equatorial plane of the sphere; it corresponds to Rossby wave instabilities of a geostrophic internal shear layer produced by differential rotation. The induction equation is computed in the whole sphere after the QG flow has been expanded along the rotation axis. Differential rotation and Rossby wave propagation are the key ingredients of this dynamo which can be interpreted in terms of Parker-[Omega] dynamo. Taking into account the quasi-geostrophy of the velocity field enables us to increase time and space resolution to compute the dynamics. For the first time, we report on numerical dynamos with very low Ekman numbers (10- 8). Because the magnetic and velocity fields are computed on different grids, we compute dynamos for very low magnetic Prandtl numbers exhibiting a scale separation between magnetic and velocity field. These dynamos are asymptotically close to rapidly rotating, metallic planetary cores
Nash Negotiation Method of Conflict Resolution for MSC Production Marketing Coordination Based on Multi-Agent

Part 6: Decision Making and Knowledge ManagementInternational audienceIn the face of increasingly market competition and diversified demand, manufacturers and dealers of Manufacturing Supply Chain (MSC) pay great effort to achieve production marketing coordination. However, it often generates conflicts in the process of production marketing coordination. For this kind of conflict problem, Multi-Agent technology is introduced. Enterprises of the supply chain are represented by Agents. The conflicts among Agents are resolved through Nash negotiation. A model of Nash Negotiation based on Agents is established. The conflict point of negotiation is determined by Stackelberg differential game. A Memetic Algorithm is proposed to solve the model. Finally, the validity of the algorithm and the model is verified by numerical experiment
Description, modeling and forecasting of data with optimal wavelets

International audienceCascade processes have been used to model many different self-similar systems, as they are able to accurately describe most of their global statistical properties. The so-called optimal wavelet basis allows to achieve a geometrical representation of the cascade process-named microcanonical cascade- that describes the behavior of local quantities and thus it helps to reveal the underlying dynamics of the system. In this context, we study the benefits of using the optimal wavelet in contrast to other wavelets when used to define cascade variables, and we provide an optimality degree estimator that is appropriate to determine the closest-to-optimal wavelet in real data. Particularizing the analysis to stock market series, we show that they can be represented by microcanonical cascades in both the logarithm of the price and the volatility. Also, as a promising application in forecasting, we derive the distribution of the value of next point of the series conditioned to the knowledge of past points and the cascade structure, i.e., the stochastic kernel of the cascade process
Prenatal stress and early-life exposure to fluoxetine have enduring effects on anxiety and hippocampal BDNF gene expression in adult male offspring

International audienceWith the growing use of selective serotonin reuptake inhibitor medications (SSRIs) for the treatment of depression during the perinatal period, questions have been raised about the longterm impact of these medications on development. We aimed to investigate how developmental SSRI exposure may alter affect-related behaviors and associated molecular processes in offspring using a rodent model of maternal stress and depression. For this purpose, prenatally stressed or non-stressed male offspring were exposed to fluoxetine (5 mg/kg/day) or vehicle, via lactation, until weaning. Primary results show that postnatal fluoxetine exposure differentially altered anxiety-like behavior by increasing anxiety in non-stressed offspring and decreasing anxiety in prenatally stressed offspring. In the hippocampus, developmental fluoxetine exposure decreased BDNF IV and TrkB mRNA expression. Prenatal stress alone also decreased escape behaviors and decreased hippocampal BDNF IV mRNA expression. These data provide important evidence for the long-term programming effects of early-life exposure to SSRIs on brain and behavior
Geometry Flexibility of Copper Iodide Clusters: Variability in Luminescence Thermochromism.

International audienceAn original copper(I) iodide cluster of novel geometry obtained by using a diphosphine ligand is reported and is formulated [Cu6I6(PPh2(CH2)3PPh2)3] (1). Interestingly, this sort of “eared cubane” cluster based on the [Cu6I6] inorganic core can be viewed as a combination of the two known [Cu4I4] units, namely, the cubane and the open-chair isomeric geometries. The synthesis, structural and photophysical characterisations, as well as theoretical study of this copper iodide along with the derived cubane (3) and open-chair (2) [Cu4I4(PPh3)4] forms, were investigated. A new polymorph of the cubane [Cu4I4(PPh3)4] cluster is indeed presented (3). The structural differences of the clusters were analyzed by solid-state nuclear magnetic resonance spectroscopy. Luminescence properties of the three clusters were studied in detail as a function of the temperature showing reversible luminescence thermochromism for 1 with an intense orange emission at room temperature. This behavior presents different feature compared to the cubane cluster and completely contrasts with the open isomer, which is almost nonemissive at room temperature. Indeed, the thermochromism of 1 differs by a concomitant increase of the two emission bands by lowering the temperature, in contrast to an equilibrium phenomenon for 3. The luminescence properties of 2 are very different by exhibiting only one single band when cooled. To rationalize the different optical properties observed, density functional theory calculations were performed for the three clusters giving straightforward explanation for the different luminescence thermochromism observed, which is attributed to different contributions of the ligands to the molecular orbitals. Comparison of 3 with its [Cu4I4(PPh3)4] cubane polymorphs highlights the sensibility of the emission properties to the cuprophilic interactions
Influence of the elastic deformation of a foam on its mobility in channels of linearly varying width

International audienceWe study foam flow in an elementary model porous medium consisting of a convergent and a divergent channel positioned side by side and possessing a fixed joint porosity. Configurations of converging or diverging channels are ubiquitous at the pore scale in porous media, as all channels linking pores possess a converging and diverging part. The resulting flow kinematics imposes asymmetric bubble deformations in the two channels, which modulate foam-wall friction and strongly impact the flux distribution. We measure, as well as quantitatively predict, the ratio of the fluxes in the two channels as a function of the channel widths by modeling pressure drops of both viscous and capillary origins. This study reveals the crucial importance of boundary-induced bubble deformation on the mobility of a flowing foam, resulting in particular in flow irreversibilit
Non-linear simulation of coiling accounting for roughness of contacts and multiplicative elastic-plastic behavior

International audienceIn this paper numerical simulations of coiling (winding of a steel strip on itself) and uncoiling are developed. Initial residual stress field is taken into account as well as roughness of contacts and elastic-plastic behavior at finite strains, considering the Tresca yield function and isotropic hardening. The main output is the residual stress field due to plastic deformations during the process. This enables to quantify additional flatness defects. The presented coiling simulation relies on a modeling strategy that consists in dividing each time step into two sub-steps. Each sub-step can be solved semi-analytically and numerical optimizations enable to obtain a general solution. Thus reasonable computation times are reached and parametric studies can be performed in order to develop coiling strategies considering the process parameters. Comparisons with previous models from the literature are presented. Moreover the comparison with a Finite Element simulation presents the same order of magnitude, however it shows that direct computations using classical FE codes are difficult to perform in terms of computation times and stability if an explicit integration scheme is chosen. Numerical results are also given in order to determine the effect of some parameters such as roughness, yield stress, applied force, strip crown or mandrel's radius
On Matrices, Automata, and Double Counting in Constraint Programming

Preprint, the final publication will be available at www.springerlink.comInternational audienceMatrix models are ubiquitous for constraint problems. Many such problems have a matrix of variablesM, with the same constraint C defined by a finitestate automaton A on each row ofMand a global cardinality constraint gcc on each column of M. We give two methods for deriving, by double counting, necessary conditions on the cardinality variables of the gcc constraints from the automaton A. The first method yields linear necessary conditions and simple arithmetic constraints. The second method introduces the cardinality automaton, which abstracts the overall behaviour of all the row automata and can be encoded by a set of linear constraints. We also provide a domain consistency filtering algorithm for the conjunction of lexicographic ordering constraints between adjacent rows ofMand (possibly different) automaton constraints on the rows. We evaluate the impact of our methods in terms of runtime and search effort on a large set of nurse rostering problem instances
Evolution of the dendritic morphology with the solidification velocity in rapidly solidified Al- 4.5wt.%Cu droplets

International audienceThe microstructure morphology of Al-4.5wt.%Cu droplets formed by the Impulse Atomization technique is investigated. Three-dimensional reconstructions by synchrotron X-ray micro-tomography of several droplets reveal different morphologies in droplets of similar diameter and produced in the same batch. Moreover, microstructural features also indicate that the development of the dendrite arms occurs in some droplets along <111> crystallographic axes instead of the usual <100> directions observed in conventional casting for the same alloy. It has been observed that such an unusual growth direction of the dendrites is directly related to the solidification velocity. We underpin these results by carrying out comparisons with a solidification model. Predictions are used to discuss the change of dendrite growth direction, as well as the existence of a dendrite growth direction range for a given type of droplets. In addition, the effect of the droplet size and the cooling gas on the dendrite growth direction range observed experimentally is also investigated by using the model. 1. Introduction Rapid solidification techniques have been developed as they enable to obtain a wide variety of structures which cannot be formed under conventional solidification processes [1]. They differ by the way to form the liquid as a strip or a droplet and by the method of heat extraction. Atomization techniques are used to make metallic powders which are used for making a desired object by pressing or by sintering [2]. The liquid metal generated as a stream breaks up into droplets by Rayleigh-Plateau instability, which subsequently solidify in a much colder medium. In the Impulse Atomization (IA) technique the liquid is pushed through a nozzle plate to form the liquid streams [3]. In order to deepen the understanding of the microstructure formation in the droplets, synchrotron X-ray micro-tomography was carried out at the European Synchrotron Radiation Facility (ESRF, Grenoble, France). Three-dimensional reconstructions of a large number of droplets were obtained, enabling the inner microstructure of the droplets to be statistically analysed for the first time. In a previous paper, we showed that four distinct morphologies could be identified in droplets of the same size and from the same batch [4]. Such a range of morphologies can be linked to a range of solidification velocities for the droplets. Indeed, while Rappaz and co-workers highlighted the <100
Electrical resistivity survey in soil science: a review .

Electrical resistivity of the soil can be considered as a proxy for the spatial and temporal variability of many other soil physical properties (i.e. structure, water content, or fluid composition). Because the method is non-destructive and very sensitive, it offers a very attractive tool for describing the subsurface properties without digging. It has been already applied in various contexts like: groundwater exploration, landfill and solute transfer delineation, agronomical management by identifying areas of excessive compaction or soil horizon thickness and bedrock depth, and at least assessing the soil hydrological properties. The surveys, depending on the areas heterogeneities can be performed in one-, two- or three-dimensions and also at different scales resolution from the centimetric scale to the regional scale. In this review, based on many electrical resistivity surveys, we expose the theory and the basic principles of the method, we overview the variation of electrical resistivity as a function of soil properties, we listed the main electrical device to performed one-, two- or three-dimensional surveys, and explain the basic principles of the data interpretation. At least, we discuss the main advantages and limits of the method
On the optimal experimental design for heat and moisture parameter estimation

32 pages, 14 figures, 3 tables, 34 references. Other author's papers can be downloaded at http://www.denys-dutykh.com/International audienceIn the context of estimating material properties of porous walls based on in-site measurements and identification method, this paper presents the concept of Optimal Experiment Design (OED). It aims at searching the best experimental conditions in terms of quantity and position of sensors and boundary conditions imposed to the material. These optimal conditions ensure to provide the maximum accuracy of the identification method and thus the estimated parameters. The search of the OED is done by using the Fisher information matrix and a priori knowledge of the parameters. The methodology is applied for two case studies. The first one deals with purely conductive heat transfer. The concept of optimal experiment design is detailed and verified with 100 inverse problems for different experiment designs. The second case study combines a strong coupling between heat and moisture transfer through a porous building material. The methodology presented is based on a scientific formalism for efficient planning of experimental work that can be extended to the optimal design of experiments related to other problems in thermal and fluid sciences