Dynamics of elastically strained islands in presence of an anisotropic surface energy

The equilibrium solutions and coarsening dynamics of strained semi-conductor islands are investigated analytically and numerically. We develop an analytical model to study the effect of surface energy anisotropy on the dynamics coarsening of islands. We propose a simple model to explain the effect of this anisotropy on the coarsening time. We find that the anisotropy slows down the coarsening. This effect is rationalised using a quasi-analytical description of the island profile

Dust Attenuation Curves in the Local Universe: Demographics and New Laws for Star-forming Galaxies and High-redshift Analogs

We study dust attenuation curves of 230,000 individual galaxies in the local universe, ranging from quiescent to intensely star-forming systems, using GALEX, SDSS, and WISE photometry calibrated on Herschel-ATLAS. We use a new method of constraining SED fits with infrared luminosity (SED+LIR fitting), and parameterized attenuation curves determined with the CIGALE SED fitting code. Attenuation curve slopes and UV bump strengths are reasonably well constrained independently from one another. We find that $A_{\lambda}/A_V$ attenuation curves exhibit a very wide range of slopes that are on average as steep as the SMC curve slope. The slope is a strong function of optical opacity. Opaque galaxies have shallower curves - in agreement with recent radiate transfer models. The dependence of slopes on the opacity produces an apparent dependence on stellar mass: more massive galaxies having shallower slopes. Attenuation curves exhibit a wide range of UV bump amplitudes, from none to MW-like; with an average strength 1/3 of the MW bump. Notably, local analogs of high-redshift galaxies have an average curve that is somewhat steeper than the SMC curve, with a modest UV bump that can be to first order ignored, as its effect on the near-UV magnitude is 0.1 mag. Neither the slopes nor the strengths of the UV bump depend on gas-phase metallicity. Functional forms for attenuation laws are presented for normal star-forming galaxies, high-z analogs and quiescent galaxies. We release the catalog of associated SFRs and stellar masses (GSWLC-2).Comment: Accepted to ApJ. GSWLC-2 catalog of SED+LIR SFRs and M* to be released Jun 1 at http://pages.iu.edu/~salims/gswlc

DustKING - the story continues: dust attenuation in NGC628

Dust attenuation is a crucial but highly uncertain parameter that hampers the determination of intrinsic galaxy properties, such as stellar masses, star formation rates and star formation histories. The shape of the dust attenuation law is not expected to be uniform between galaxies, nor within a galaxy. Our DustKING project was introduced at the first BINA workshop in 2016 and aims to study the variations of dust attenuation curves in nearby galaxies. At the second BINA workshop in 2018, I presented the results of our pilot study for the spiral galaxy NGC628. We find that the average attenuation law of this galaxy is characterised by a MW-like bump and a steep UV slope. Furthermore, we observe intriguing variations within the galaxy, with regions of high $A_V$ exhibiting a shallower attenuation curve. Finally, we discuss how our work might benefit from data taken with the UVIT from the Indian AstroSat mission.Comment: 8 pages, 6 figures, Proceedings paper of the second Belgo-Indian Network for Astronomy & astrophysics (BINA) workshop, accepted for publication in the Bulletin de la Soci\'et\'e Royale des Sciences de Li\`eg

DustKING, the story continues : dust attenuation in NGC 628

Dust attenuation is a crucial but highly uncertain parameter that hampers the determination of in- trinsic galaxy properties, such as stellar masses, star formation rates and star formation histories. The shape of the dust attenuation law is not expected to be uniform between galaxies, nor within a galaxy. Our DustKING project was introduced at the first BINA workshop in 2016 and aims to study the variations of dust attenuation curves in nearby galaxies. At the second BINA workshop in 2018, I presented the results of our pilot study for the spiral galaxy NGC 628. We find that the average attenuation law of this galaxy is characterised by a MW-like bump and a steep UV slope. Furthermore, we observe intriguing variations within the galaxy, with regions of high AV exhibiting a shallower attenuation curve. Finally, we discuss how our work might benefit from data taken with the UVIT from the Indian AstroSat mission

Quasipatterns in a parametrically forced horizontal fluid film

International audienceWe shake harmonically a thin horizontal viscous fluid layer (frequency forcing Ω, only one harmonic), to reproduce the Faraday experiment and using the system derived in [31] invariant under horizontal rotations. When the physical parameters are suitably chosen, there is a critical value of the amplitude of the forcing such that instability occurs with at the same time the mode oscillating at frequency Ω/2, and the mode with frequency Ω. Moreover, at criticality the corresponding wave lengths kc and k′c are such that if we define the family of 2q equally spaced (horizontal) wave vectors kj on the circle of radius kc , then kj + kl = k′n, with |kj| = |kl| = kc , |k′n| = k′c .It results under the above conditions that 0 is an eigenvalue of the linearized operator in a space of time-periodic functions (frequencyΩ/2) having a spatially quasiperiodic pattern if q ≥ 4. Restricting our study to solutions invariant under rotations of angle 2π/q, gives a kernel of dimension 4.In the spirit of Rucklidge and Silber (2009) [29] we derive formally amplitude equations for perturbations possessing this symmetry. Then we give simple necessary conditions on coefficients, for obtaining the bifurcation of (formally) stable time-periodic (frequency Ω/2) quasipatterns. In particular,we obtain a solution such that a time shift by half the period, is equivalent to a rotation of angle π/q of the pattern

Open SVC decoder: a flexible SVC library

International audienceThis paper describes the Open SVC Decoder project, an open source library which implements the Scalable Video Coding (SVC) standard, the latest standardized by the Joint Video Team (JVT). This library has been integrated into open source players The Core Pocket Media Player (TCPMP) and mplayer, in order to be deployed over different platforms with different operating systems

: Aspects idéologiques des débats linguistiques en Provence et ailleurs

Numéro coordonné par J. Costa et M. Gasquet-CyrusInternational audienceCe volume de la revue Lengas traite de la compétition et des débats idéologiques au sein des mouvements de revitalisation linguistique, en Provence mais aussi en Pays Valencien, en Corse et au Costa Rica