Dismantling the Mantel tests

The simple and partial Mantel tests are routinely used in many areas of evolutionary biology to assess the significance of the association between two or more matrices of distances relative to the same pairs of individuals or demes. Partial Mantel tests rather than simple Mantel tests are widely used to assess the relationship between two variables displaying some form of structure. We show that contrarily to a widely shared belief, partial Mantel tests are not valid in this case, and their bias remains close to that of the simple Mantel test. We confirm that strong biases are expected under a sampling design and spatial correlation parameter drawn from an actual study. The Mantel tests should not be used in case auto-correlation is suspected in both variables compared under the null hypothesis. We outline alternative strategies. The R code used for our computer simulations is distributed as supporting material

Detection of Jovian seismic waves: a new probe of its interior structure

Knowledge of Jupiter's deep interior would provide unique constraints on the formation of the Solar System. Measurement of its core mass and global composition would shed light on whether the planet formed by accretion or by direct gravitational collapse. At present, the inner structure of Jupiter is poorly constrained and seismology, which consists of identifying acoustic eigenmodes, offers a way to directly measure its deep sound speed profile, and thus its physical properties. Seismology of Jupiter has been considered since the mid 1970s, but hitherto the various attempts to detect global modes led, at best, to ambiguous results. We report the detection of global modes of Jupiter, based on radial velocity measurements performed with the SYMPA Fourier spectro-imager. The global seismic parameters that we measure include the frequency of maximum amplitude 1213+/-50 \mu Hz, the mean large frequency spacing between radial harmonics 155.3+/-2.2 \mu Hz and the mode maximum amplitude 49 (-10/+8) cm/s, all values that are consistent with current models of Jupiter. This result opens the way to the investigation of the inner structure of the Solar System's giant planets based on seismology techniques.Comment: Accepted in Astronomy & Astrophysics (8 pages, 9 figures

La ville et son élan vital

Si Marcel Poëte et Robert Auzelle ont parlé de ville vivante, c'est pour une large part dans un rapport constant à la philosophie de Bergson. Le mouvement créateur de la ville, observé par l'historien et mis en œuvre par l'urbaniste, exige pour être compris une implication de tout être dans l'élan vital. C'est cette notion bergsonienne, longtemps travaillée par Poëte, qui se fait jour dans les travaux comme dans les écrits d'Auzelle. De Bergson à Poëte, puis de Poëte à Auzelle, des idées philosophiques d'abord étrangères à l'urbanisme passent en se transformant dans l'histoire des villes et dans la réalisation urbaine.Marcel Poëte and Robert Auzelles'theoires about the town as an evolving crea­tion are directly connected to Bergson's philosophy. Poëte, the historian, saw the creative movement in the evolution of a town and Auzelle, the town-planner, embraced this in his town planning. This concept of the town as a living, evolving organism can only be fully understood by those who are personally involved in the vital impulse. Poëte thought of this Bergsonian concept and this appears in Auzelle's writings and urban develop­ments. From Bergson to Poëte, then from Poëte to Auzelle, philosophical concepts, at first apparently irrelevant to town planning, evolved to become helpful to understand history of towns and to take part in the creation of town

La Société française des urbanistes et l’Institut d’urbanisme : deux usages du réseau pour une même cause ?

En 1911 est créée la Société française des architectes et urbanistes, elle devient en 1919 la SFU. Issue du Musée social, sa vocation est de promouvoir une science et un art urbain pour l’amélioration des villes. Le réseau des réformateurs sociaux a croisé celui de certains architectes pour lui donner naissance.L’Institut d’urbanisme intègre l’Université en 1924 après avoir connu divers statuts. Sa genèse est étrangère aux acteurs de la SFU : son réseau de fondation est lié à l’Université et aux institutions publiques.Peu d’acteurs ont appartenu en même temps à ces deux créations pour la promotion de l’urbanisme. On étudiera ici le rôle des réseaux de fondation et l’originalité de leurs fonctionnements. L’usage du réseau est en effet déterminant pour l’idée même d’urbanisme dans les deux premières décennies du xxe siècle

CoRoT: harvest of the exoplanet program

One of the objectives of the CoRoT mission is the search for transiting extrasolar planets using high-precision photometry, and the accurate characterization of their fundamental parameters. The CoRoT satellite consecutively observes crowded stellar fields since February 2007, in high-cadence precise photometry; periodic eclipses are detected and analysed in the stellar light curves. Then complementary observations using ground-based facilities allows establishing the nature of the transiting body and its mass. CoRoT has acquired more than 163,000 light curves and detected about 500 planet candidates. A fraction of them (5%) are confirmed planets whose masses are independently measured. Main highlights of the CoRoT discoveries are: i) the variety of internal structures in close-in giant planets, ii) the characterisation of the first known transiting rocky planet, CoRoT-7 b, iii) multiple constraints on the formation, evolution, role of tides in planetary systems.Comment: Icarus, in press, special issue on Exoplanet

Exact approaches for solving a covering problem with capacitated subtrees

Experiments presented in this paper were carried out using the PLAFRIM experimental testbed, being developed under the Inria PlaFRIM development action with support from Bordeaux INP, LABRI and IMB and other entities: Conseil Régional d’Aquitaine, Université de Bordeaux, CNRS and ANR in accordance to the programmed’investissements d’Avenir (seehttps://www.plafrim.fr/)International audienceIn this document, we present a covering problem where vertices of a graph have to be covered by rooted subtrees. We present three mixed-integer linear programming models, two of which are compact while the other is based on Dantzig-Wolfe decomposition. In the latter case, we focus on the column generation subproblem, for which we propose several algorithms. Numerical results are obtained using instances from the literature and instances based on a real-life districting application. Experiments show that the branch-and-price algorithm is able to solve much bigger instances than the compact model, which is limited to very small instance sizes

Effets de phytobiotiques sur les performances de croissance et l'équilibre ou microbiote digestif du poulet de chair

Suite à l interdiction de l utilisation des antibiotiques facteurs de croissances dans l alimentation animale en 2006, des méthodes alternatives sont proposées aux éleveurs, notamment les phytobiotiques. Cependant, l efficacité de ces molécules, telle que décrite dans la littérature, est variable, et leur modes d action est mal connu. Nous avons pu mettre en évidence un effet important des conditions d élevage dans la réponse des poulets aux deux modèles de phytobiotiques étudiés. Ils améliorent les performances zootechniques des animaux placés dans des conditions défavorables à leur croissance. Dans des conditions très dégradées, l utilisation couplée de phytobiotiques portant des activités biologiques variées s est avéré plus efficace. De plus, les modèles étudiés comprenant de nombreuses molécules exerçant une activité antibactérienne in vitro, nous avons étudié in vivo la réponse du microbiote digestif à leur ingestion par l animal. Des modifications du microbiote digestif ont été observées et pourraient en partie expliquer l amélioration de leur croissance.The banning of antibiotic growth promoters for livestock feeding led to the development of several alternatives, including phytobiotics. However, their efficiency as growth promoters is inconstant between scientific studies and their mechanisms of action are poorly known. In the present work, the rearing conditions strongly affect the efficiency of two phytobiotics models. They improved the chickens growth performance when the rearing conditions were unfavorable to the growth. When strongly deteriorated, the combination of phytobiotics showing various biological activities was more efficient. As the phytobiotics used in the present study contains numerous molecules with an in vitro antibacterial activity, the impact of those phytobiotics on chickens digestive microbiota was studied in vivo. Changes in chickens digestive microbiota were observed which could partly explain the chickens growth improvement.TOURS-Bibl.électronique (372610011) / SudocSudocFranceF