Infrared dynamics in de Sitter space from Schwinger-Dyson equations

We study the two-point correlator of an O(N) scalar field with quartic self-coupling in de Sitter space. For light fields in units of the expansion rate, perturbation theory is plagued by large logarithmic terms for superhorizon momenta. We show that a proper treatment of the infinite series of self-energy insertions through the Schwinger-Dyson equations resums these infrared logarithms into well defined power laws. We provide an exact analytical solution of the Schwinger-Dyson equations for infrared momenta when the self-energy is computed at two-loop order. The obtained correlator exhibits a rich structure with a superposition of free-field-like power laws. We extract mass and field-strength renormalization factors from the asymptotic infrared behavior. The latter are nonperturbative in the coupling in the case of a vanishing tree-level mass.Comment: 9 pages, 3 figures, published version, some material has been added, title change

The social space of Muslim spokespersons in India: a typology

Who speaks for Muslims in India? Who are the leaders of the so-called “Muslim organizations”? What family and educational background do they come from? What is their relation to state authorities? This article addresses these questions by presenting a unique biographical database and the results of statistical treatments (multiple correspondence analysis and hierarchical clustering on principal components) of this data. This database includes the office-bearers of a selected set of organizations that make representative claims in the name of Muslims in India. Our analysis thus delineates the contours of the social space of Muslim spokespersons in India and describes how it is structured. We will highlight the important distinctions that exist among these Muslim spokespersons, such as the opposition between secular figures and religious scholars, the political sphere and the educational sphere, and between central power and regional dynamics. This analysis allows us, more broadly, to examine the role of state authorities in the definition of the Muslim spokespersons, thus highlighting some of the characteristic features of state secularism in India

SABBAC: online Structural Alphabet-based protein BackBone reconstruction from Alpha-Carbon trace

SABBAC is an on-line service devoted to protein backbone reconstruction from alpha-carbon trace. It is based on the assembly of fragments taken from a library of reduced size, selected from the encoding of the protein trace in a hidden Markov model-derived structural alphabet. The assembly of the fragments is achieved by a greedy algorithm, using an energy-based scoring. Alpha-carbon coordinates remain unaffected. SABBAC simply positions the missing backbone atoms, no further refinement is performed. From our tests, SABBAC performs equal or better than other similar on-line approach and is robust to deviations on the alpha-carbon coordinates. It can be accessed at

When Geopolitical and Limnology Collide: New Representation of Lake Borders.

This work should demonstrate the interest of a new concept to show the link between limnology and geopolitics. With the term of “limnic border”, we can demonstrate the difference between the zonal border in two dimensions, typical for geopolitics and the deep border, typical for limnology. The introduction will constitute a resume of the historic and epistemological evolution of the vision about border and natural lake and how geopolitical and limnology develop in different ways. We demonstrate the interest to associate these two views, with regard to a general approach associating “biophysical vision” and “anthropic vision”. With the definition of how we can think multiple separation about transboundary lake, we should demonstrate the accuracy and the interest of a new three-dimensional vision, “the limnic border”. We will demonstrate how we can show the accuracy of this new concept by a description of a cross methodology, included limnologic measures and survey

Ultrasonic characterization of porous silicon using a genetic algorithm to solve the inverse problem

International audienceThis paper presents a method for ultrasonic characterization of porous silicon in which a genetic algorithm based optimization is used to solve the inverse problem. A one dimensional model describing wave propagation through a water immersed sample is used in order to compute transmission spectra. Then, a water immersion wide bandwidth measurement is performed using insertion/substitution method and the spectrum of signals transmitted through the sample is calculated using Fast Fourier Transform. In order to obtain parameters such as thickness, longitudinal wave velocity or density, a genetic algorithm based optimization is used.A validation of the method is performed using aluminum plates with two different thicknesses as references: a good agreement on acoustical parameters can be observed, even in the case where ultrasonic signals overlap.Finally, two samples, i.e. a bulk silicon wafer and a porous silicon layer etched on silicon wafer, are evaluated. A good agreement between retrieved values and theoretical ones is observed. Hypothesis to explain slight discrepancies are proposed

Computational Study of Carbon Nanoparticle Formation during Thermal Decomposition of Methane

International audienceThermal decomposition of methane is a suitable and eco-friendly way to simultaneously produce hydrogen and carbon black. A parametric study is made on a two-dimensional model of methane thermal decomposition reactor. This modelling attaches utmost importance in the radiation phenomenon and particle population evolution

Une nouvelle tarification des réseaux pour favoriser la transition énergétique

La transition énergétique modifie la manière de produire, consommer, stocker et échanger l’énergie. Dans cette transition, les prix doivent orienter les choix et donner des signaux corrects aux consommateurs. Dans ce numéro de Regards économiques, nous analysons le comportement des prosumers, les ménages qui sont à la fois producteurs et consommateurs d’énergie. Nous montrons que les tarifs en place ne donnent pas de bons signaux et qu’il faut les faire évoluerTEC

Modular interpretation of heterogeneous modeling diagrams into synchronous equations using static single assignment

The ANR project SPACIFY develops a domain-specific programming environment, Synoptic, to engineer embedded software for space applications. Synoptic is an Eclipse-based modeling environment which supports all aspects of aerospace software design. As such, it is a domain-specific environment consisting of heterogeneous modeling and programming principles defined in collaboration with the industrial partners and end users of the project : imperative synchronous programs, data-flow diagrams, mode automata, blocks, components, scheduling, mapping and timing. This article focuses on the essence and distinctive features of its behavioral or programming aspects : actions, flows and automata, for which we use the code generation infrastructure of the synchronous modeling environment SME. It introduces an efficient method for transforming a hierarchy of blocks consisting of actions (sequential Esterel-like programs), data-flow diagrams (to connect and time modules) and mode automata (to schedule or mode blocks) into a set of synchronous equations. This transformation minimizes the needed state variables and block synchronizations. It consists of an inductive static-single assignment transformation algorithm across a hierarchy of blocks that produces synchronous equations. The impact of this new transformation technique is twofold. With regards to code generation objectives, it minimizes the needed resynchronization of each block in the system with respects to its parents, potentially gaining substantial performance from way less synchronizations. With regards to verification requirements, it minimizes the number of state variables across a hierarchy of automata and hence maximizes model checking performances

Criteria for fast and selective α precipitation at β grain boundaries in Ti-alloys Consequence for in-service microstructures

International audienceThe potential for β grain boundaries (GBs) to give rise to large Widmanstätten colonies was determined through the observation of a large amount of precipitates at β GBs in a β-metastable titanium alloy using electron backscatter imaging and diffraction. The most critical boundaries are those which transform early and where a type of Variant Selection (VS) called double Burgers VS occurs. This mechanisms take place at 'special' β boundaries misoriented so that an α precipitate can be related to both grains through the Burgers relation. It was shown that the most critical GBs have a disorientation at an angle of less than 10° from 49.5°/ or 60°/. A simulation study allowed those boundaries to be quantifed in crystallographic textures typical of industrial products. Those texture have then been discussed as a function of their potential to form large Widmanstätten colonies

Criteria for fast and selective α precipitation at β grain boundaries in Ti-alloys Consequence for in-service microstructures

International audienceThe potential for β grain boundaries (GBs) to give rise to large Widmanstätten colonies was determined through the observation of a large amount of precipitates at β GBs in a β-metastable titanium alloy using electron backscatter imaging and diffraction. The most critical boundaries are those which transform early and where a type of Variant Selection (VS) called double Burgers VS occurs. This mechanisms take place at 'special' β boundaries misoriented so that an α precipitate can be related to both grains through the Burgers relation. It was shown that the most critical GBs have a disorientation at an angle of less than 10° from 49.5°/<110> or 60°/<110>. A simulation study allowed those boundaries to be quantifed in crystallographic textures typical of industrial products. Those texture have then been discussed as a function of their potential to form large Widmanstätten colonies