Peak exclusion, stochasticity and convergence of perturbative bias expansions in 1+1 gravity

The Lagrangian peaks of a 1D cosmological random field representing dark matter are used as a proxy for a catalogue of biased tracers in order to investigate the small-scale exclusion in the two-halo term. The two-point correlation function of peaks of a given height is numerically estimated and analytical approximations that are valid inside the exclusion zone are derived. The resulting power spectrum of these tracers is investigated and shows clear deviations from Poisson noise at low frequencies. On large scales, the convergence of a perturbative bias expansion is discussed. Finally, we go beyond Gaussian statistics for the initial conditions and investigate the subsequent evolution of the two-point clustering of peaks through their Zel'dovich ballistic displacement, to clarify how exclusion effects mix up with scale-dependencies induced by nonlinear gravitational evolution. While the expected large-scale separation limit is recovered, significant deviations are found in the exclusion zone that tends in particular to be reduced at later times. Even though these findings apply to the clustering of one-dimensional tracers, they provide useful insights into halo exclusion and its impact on the two-halo term.Comment: 16 pages, 9 figures, accepted for publication in MNRA

Efficient Generation of Stable Planar Cages for Chemistry

In this paper we describe an algorithm which generates all colored planar maps with a good minimum sparsity from simple motifs and rules to connect them. An implementation of this algorithm is available and is used by chemists who want to quickly generate all sound molecules they can obtain by mixing some basic components.Comment: 17 pages, 7 figures. Accepted at the 14th International Symposium on Experimental Algorithms (SEA 2015

Régulation bancaire européenne : quand l’union fait la force

A l’heure où l’Amérique s’apprête, sous l’impulsion de son nouveau président Donald Trump, à mettre fin à la régulation bancaire adoptée en 2010 par l’administration Obama, l’Europe entame une troisième année d’Union bancaire (Antonin et al., 2017) et se prépare à l’arrivée d’une nouvelle réglementation prudentielle. [Premier paragraphe]At a time when America, under the impulse of its new president Donald Trump, is preparing to put an end to the banking regulation adopted in 2010 by the Obama administration [1], Europe is entering a third year of the Banking Union (Antonin et al., 2017) and is readying to introduce new prudential regulations. [First paragraph

Arbitrage between Energy Efficiency and Carbon Management in the Industry Sector: An Emerging vs. Developed Country Discrimination

International audienceFollowing the Copenhagen Climate Conference in 2009, some countries have adopted carbon abatement pledges. As energy savings are a source of indirect carbon reduction, those pledges will impact the development of Energy Efficiency solutions. This study aims to quantify those impacts and determine their sensitivity to COP15 pledges within the competition with other cleaner technologies, especially on the supply-side. The study relies on the TIAM-FR model, which is a 15-region world version of the MARKAL/TIMES model family, where an Energy Efficiency-dedicated module was implemented. A focus is given on Europe, United States and China; and only the implementation of the Energy Efficiency solutions in the industrial sector is considered. On the supply side, the level of power generation is weakly changed with the carbon mitigation constraint while the power mix has a strong sensitivity for pledges more strict than COP15. On the demand side, Energy Efficiency implementation appears as the only lever in mature countries to achieve COP15 variant pledges, whereas a competition with cleaner generation technologies is pointed out according to the stringency of the pledge adopted by China

Post-Kyoto policy implications on the energy system: A TIAM-FR long-term planning exercise

World Energy Council : http://www.worldenergy.org/documents/congresspapers/366.pdfInternational audienceThe aim of this study is to discuss the long term analysis of post-Kyoto commitments, with the modelling tool ETSAP-TIAM-FR. Through the specification of CO2 mitigation targets scenarios covering the period 2000-2050, this analysis focuses on the effects of these carbon constraints on several indicators such as global and regional CO2 emissions, the cost of the climate policy, carbon marginal costs, the primary energy consumption and the energy mix. This paper compares global efforts of CO2 mitigation with the cost of carbon and finally discusses the development of CCS technologies

Intrinsic alignment of simulated galaxies in the cosmic web: implications for weak lensing surveys

The intrinsic alignment of galaxy shapes (by means of their angular momentum) and their cross-correlation with the surrounding dark matter tidal field are investigated using the 160 000, z=1.2 synthetic galaxies extracted from the high-resolution cosmological hydrodynamical simulation Horizon-AGN. One- and two-point statistics of the spin of the stellar component are measured as a function of mass and colour. For the low-mass galaxies, this spin is locally aligned with the tidal field `filamentary' direction while, for the high-mass galaxies, it is perpendicular to both filaments and walls. The bluest galaxies of our synthetic catalog are more strongly correlated with the surrounding tidal field than the reddest galaxies, and this correlation extends up to 10 Mpc/h comoving distance. We also report a correlation of the projected ellipticities of blue, intermediate mass galaxies on a similar scale at a level of 10^(-4) which could be a concern for cosmic shear measurements. We do not report any measurable intrinsic alignments of the reddest galaxies of our sample. This work is a first step toward the use of very realistic catalog of synthetic galaxies to evaluate the contamination of weak lensing measurement by the intrinsic galactic alignments.Comment: 15 pages, accepted for publication in MNRA

Momocs: Outline Analysis Using R

We introduce here Momocs, a package intended to ease and popularize modern morphometrics with R, and particularly outline analysis, which aims to extract quantitative variables from shapes. It mostly hinges on the functions published in the book entitled Modern Morphometrics Using R by Claude (2008). From outline extraction from raw data to multivariate analysis, Momocs provides an integrated and convenient toolkit to students and researchers who are, or may become, interested in describing the shape and its variation. The methods implemented so far in Momocs are introduced through a simplistic case study that aims to test if two sets of bottles have different shapes

Strain superlattices and macroscale suspension of Graphene induced by corrugated substrates

We investigate the organized formation of strain, ripples and suspended features in macroscopic CVD-prepared graphene sheets transferred onto a corrugated substrate made of an ordered arrays of silica pillars of variable geometries. Depending on the aspect ratio and sharpness of the corrugated array, graphene can conformally coat the surface, partially collapse, or lay, fakir-like, fully suspended between pillars over tens of micrometers. Upon increase of pillar density, ripples in collapsed films display a transition from random oriented pleats emerging from pillars to ripples linking nearest neighboring pillars organized in domains of given orientation. Spatially-resolved Raman spectroscopy, atomic force microscopy and electronic microscopy reveal uniaxial strain domains in the transferred graphene, which are induced and controlled by the geometry. We propose a simple theoretical model to explain the transition between suspended and collapsed graphene. For the arrays with high aspect ratio pillars, graphene membranes stays suspended over macroscopic distances with minimal interaction with pillars tip apex. It offers a platform to tailor stress in graphene layers and open perspectives for electron transport and nanomechanical applications

Chloride-induced alterations of the passive film on 316L stainless steel and blocking effect of pre-passivation

International audienceElectrochemical polarization measurements were combined with surface analysis by Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), X-Ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) to study the alterations of the passive film on 316L austenitic stainless steel induced by the presence of chlorides in sulfuric acid electrolyte. The work was performed at a stage of initiation of localized corrosion preceding metastable pitting at the micrometer scale as verified by current transient analysis and AFM. The results show that Cl-ions enter the bilayer structure of the surface oxide already formed in the native oxide-covered initial surface state at concentrations below the detection limit of XPS (< 0.5 at%), mostly in the hydroxide outer layer where Fe(III) and Mo(IV,VI) species are concentrated but barely in the oxide inner layer enriched in Cr(III). Their main effect is to produce a less resistive passive state by poisoning dehydroxylation and further Cr(III) and Mo(IV,VI) enrichments obtained in the absence of chlorides. This detrimental effect can be suppressed by pre-passivation in a Cl-free electrolyte, which blocks the entry of chlorides in the passive film, including in the outer exchange layer, and enables the beneficial aging-induced variations of the composition to take place despite the presence of chlorides in the environment