Company Presence as a Marker of Urban Development in France

Since the Industrial Revolution, entreprises have left their imprint on the urban landscape and local government. This paper begins with an historical context on the subject which is followed by an analysis of the different influences of enterprises on town planning, housing and local urban and social policies

Citizen Consumption and Public Policies: Good Complements against Market Failures?

Citizen consumption has become over the past few years an ever growing type of behaviour, in which citizens express by their consumption choices their political, environmental and ethical preferences. This paper wonders to what extend citizen consumption may represent an effective and fair instrument against market failures. Overall, it seems that it is better to consider citizen consumption as a complement to public policies.citizen consumption, environment, ethics, public policies

Les comptes de la forêt française : Un outil d'évaluation intégré des biens et services (marchands et non marchands) fournis par la forêt

L'importance de la forêt pour la société rend nécessaire l’évaluation du patrimoine forestier qu’elle représente, des biens et services qu’elle produit et du fonctionnement de la filière. Une comptabilité économique et environnementale régulière reposant sur une méthodologie spécifique permet de structurer l'information en un outil d'analyse unique, facilitant l'aide à la décision et l'évaluation des politiques publiques. Les évaluations réalisées pour la France montrent que la production de bois est loin d'être la seule source de bénéfice liée à la forêt. La séquestration du carbone, les activités récréatives ou les fonctions écologiques sont des exemples de services que l’on parvient à intégrer aux comptes usuels. La prise en compte des fonctions non marchandes des espaces forestiers français contribuerait, dans l’hypothèse la plus haute, à quintupler la valeur de la forêt restreinte à sa fonction d’approvisionnement en bois.

Optimisation de l’allocation de ressources dans un réseau de télécommunications par coloration impropre de graphes

RÉSUMÉ : Dans cette thèse, nous traitons le problème d'allocation de ressources pour les réseaux de télécommunications, dont le développement ne cesse de s'intensifier tant la demande en transmission de données est élevée à travers le monde. Malheureusement, ces ressources sont limitées et il devient de plus en plus difficile de satisfaire les besoins des utilisateurs, d'où l'intérêt de mettre en oeuvre des méthodes mathématiques adaptées à cette problématique. De telles techniques ont été développées depuis l'apparition des premiers réseaux dans les années 1970, mais l'évolution de la technologie sans fil et l'amélioration des puissances de calculs informatiques nécessitent de constamment mettre à jour les modèles utilisés, ainsi que les méthodes pour les résoudre; cette thèse s'inscrit dans cette dynamique. Nous proposons ici un nouveau modèle d'assignation de canaux qui suppose l'existence d'une entité capable de centraliser les données recueillies au niveau des usagers, à l'échelle métropolitaine. En particulier, nous proposons de maximiser le nombre d'usagers pouvant être connectés simultanément au réseau. Nous verrons en quoi ce modèle est nouveau mais tout à fait réaliste compte tenu des modèles existants. L'un des aspects originaux de cette thèse est le fait de remettre la théorie des graphes au goût du jour pour traiter ce problème d'affectation. Les notions de stabilité et de coloration impropre sont en effet intimement liées à ce problème. Nous verrons également qu'une généralisation de la fonction de Lovasz permet de dériver une borne supérieure sur l'objectif, plus serrée que la relaxation linéaire du modèle en nombres entiers associé. La théorie des graphes est un outil de modélisation très puissant, intimement liée à l'algorithmique inhérente aux problèmes combinatoires complexes. Nous verrons comment prendre à contre-pied l'explosion combinatoire de ce problème NP-difficile sans compromettre la qualité des solutions obtenues, en généralisant les notions de degré et de degré de saturation d'un sommet, à la base des heuristiques de coloration les plus populaires. Les algorithmes développés seront analysés théoriquement via les notions de complexité, de garantie et de plus petit graphe sous-optimal, mais aussi numériquement: ceux-ci seront comparés aux méthodes d'affectation classiques, à savoir la réutilisation de fréquence fractionnée. Enfin, nous étendrons le modèle proposé sur un horizon de temps, et traiterons le problème lorsque les données ne sont pas entièrement connues à l'avance mais apparaissent au fur et à mesure. En résumé, réseaux de télécommunications, théorie des graphes, algorithmique et explosion combinatoire sont les ingrédients principaux de cette thèse: il s'agit bel et bien de recherche opérationnelle!----------ABSTRACT : Since the 1970's wireless networks have constantly been striving to meet consumers increasing demands, while the necessary resources (electromagnetic frequencies) are becoming increasingly scarce. In this thesis, we address the problem of allocating a channel to a maximum number of mobiles, in order to maximize the number of users that are simultaneously connected to the network. This is a typical assignment problem, for which operations research provides the adequate tools. We propose a new model based on the existence of a calculator capable of dealing with data at a metropolitan scale. Although ambitious, this scheme remains realistic given the latest developments of cloud computing and virtualization technologies. Most importantly, part of the originality of this model is its link with graph theory. We will see how the concepts of stability and improprer weighted coloring are intimately related to the channel assignment problem. Also, we will show how a generalization of Lovasz's function can be used to derive an upper bound on the objective function, tighter than the linear relaxation of the associated integer model. As one knows, a graph theory approach is often related to combinatorics and its difficulties, namely the combinatorial explosion of any NP-hard problem. We will see how to cope with this aspect, at the crossroads between fundamental and applied research. In particular, we will generalize the concepts of degree and saturation degree of a vertex, which are essential components of most of the popular vertex coloring heuristics. The proposed algorithms are analyzed both theoretically - through computational complexity, performance guarantee and smallest suboptimal graphs -, and numerically: a set of test results are reported in which the heuristics are compared to classical allocation techniques based on fractional frequency reuse. Last but not least, the model is extended over a rolling horizon and on-line algorithms are proposed to tackle the problem when data is not known in advance but appears iteratively. In summary, wireless networks, graph theory, algorithms and combinatorial explosion are the main ingredients to this thesis, which definitely lies in the scope of operations research

Molecular evolution of the crustacean hyperglycemic hormone family in ecdysozoans

<p>Abstract</p> <p>Background</p> <p>Crustacean Hyperglycemic Hormone (CHH) family peptides are neurohormones known to regulate several important functions in decapod crustaceans such as ionic and energetic metabolism, molting and reproduction. The structural conservation of these peptides, together with the variety of functions they display, led us to investigate their evolutionary history. CHH family peptides exist in insects (Ion Transport Peptides) and may be present in all ecdysozoans as well. In order to extend the evolutionary study to the entire family, CHH family peptides were thus searched in taxa outside decapods, where they have been, to date, poorly investigated.</p> <p>Results</p> <p>CHH family peptides were characterized by molecular cloning in a branchiopod crustacean, <it>Daphnia magna</it>, and in a collembolan, <it>Folsomia candida</it>. Genes encoding such peptides were also rebuilt <it>in silico </it>from genomic sequences of another branchiopod, a chelicerate and two nematodes. These sequences were included in updated datasets to build phylogenies of the CHH family in pancrustaceans. These phylogenies suggest that peptides found in Branchiopoda and Collembola are more closely related to insect ITPs than to crustacean CHHs. Datasets were also used to support a phylogenetic hypothesis about pancrustacean relationships, which, in addition to gene structures, allowed us to propose two evolutionary scenarios of this multigenic family in ecdysozoans.</p> <p>Conclusions</p> <p>Evolutionary scenarios suggest that CHH family genes of ecdysozoans originate from an ancestral two-exon gene, and genes of arthropods from a three-exon one. In malacostracans, the evolution of the CHH family has involved several duplication, insertion or deletion events, leading to neuropeptides with a wide variety of functions, as observed in decapods. This family could thus constitute a promising model to investigate the links between gene duplications and functional divergence.</p

Passive control of wall shear stress and mass transfer generated by submerged lobed impinging jet

International audienceParticle image velocimetry was used to investigate the flow field in an impinging lobed daisy hemispherical nozzle jet in comparison to its counterpart round jet, at a Reynolds number of 5620 based on the exit velocity and the equivalent diameter D e of the nozzle. The limitations of the PIV technique in the vicinity of the target wall due to the laser scattering were addressed by using the electrodiffusion (ED) technique to determine the wall shear rate distribution. The distribution of the mass transfer coefficient is also obtained using the ED technique. The target wall is placed at a distance H = 2D e from the plane tangent to the nozzle, at the center of the orifice. The entrainment of ambient fluid in the free jet region, which is larger in the lobed jet compared to the round jet, feeds in turn the wall jet region. The maximum wall shear rate was found significantly higher in the daisy jet, with an excess of 93 % compared to the reference round jet. The maximum mass transfer is 35 % higher in the former compared to the latter. Therefore, the hemispherical daisy nozzle is an excellent candidate in passive strategies to enhance local skin-friction and the subsequent local mass transfer at a constant exit Reynolds numbe

PIV and Electrodiffusion diagnostics of flow field, wall shear stress and mass transfer beneath three round submerged impinging jets

International audienceThis paper reports on measurements of velocities, wall shear rates and mass transfer in an impinging round jet issued from a round nozzle. The effect of the nozzle shape on transfer phenomena was investigated. A round orifice perforated either on a flat plate (RO/P) or on a hemispherical surface (RO/H) was compared to a reference convergent nozzle (CONV). All the nozzles have the same exit diameter D. The exit volumetric flow rate was also conserved and led to the same Reynolds number based on the exit bulk velocity, Reb = 5620. The nozzle-to-wall distance was constant and equal to 2D. The Particle Image Velocimetry technique (PIV) was used to capture the jet flow field. The limitations of the PIV technique in the vicinity of the target disc are addressed by using the electrodiffusion technique (ED) to obtain the wall shear rate distribution. The ED technique was extended for the measurement of local mass transfer distribution and global mass transfer on the target disc. The whole velocity field, wall shear rates and mass transfer in the three impinging round jets were compared. It was shown that at constant volumetric flow rate, the use of an orifice nozzle not only improves wall shear rate, but also increases local and global mass transfer. The global mass transfer on a target disc of a 3.2 D diameter is 25% and 31% higher for RO/H and RO/P nozzles, respectively, compared to the reference CONV nozzle. The orifice nozzles generate narrower exit profiles relatively to the convergent nozzle. The vena contracta effect in orifice jets, more intense with RO/P than with RO/H, generates an increase of the exit centerline velocity. The hemispherical surface of RO/H nozzle stretches the flow at the exit and somewhat attenuates the vena contracta effect. The characteristic scale representation of the data confirms the origin of the observed differences between the three jets. A link between the wall shear stress and the mass transfer is revealed. The wall shear rate and the mass transfer are in a close relationship with the near field flow features, themselves affected by the nozzle geometry. Time-resolved tomographic PIV technique reveals that the wall shear rate fluctuation is related to the dynamics of the jet coherent structures. The instantaneous PIV fields indicates the formation of secondary vortices in the region where a secondary peak in local mass transfer emerges. The level of this secondary peak is sensitive to the nozzle shape. The higher is the jet acceleration, the more intense is the level of the secondary pea

Emulador de Turbina de Geração Eólica com GSIP Empregando Inversor de Frequência

não const

A comparison of the olfactory gene repertoires of adults and larvae in the noctuid moth Spodoptera littoralis

International audienceTo better understand the olfactory mechanisms in a lepidopteran pest model species, the cotton leafworm Spodoptera littoralis, we have recently established a partial transcriptome from adult antennae. Here, we completed this transcriptome using next generation sequencing technologies, namely 454 and Illumina, on both adult antennae and larval tissues, including caterpillar antennae and maxillary palps. All sequences were assembled in 77,643 contigs. Their analysis greatly enriched the repertoire of chemosensory genes in this species, with a total of 57 candidate odorant-binding and chemosensory proteins, 47 olfactory receptors, 6 gustatory receptors and 17 ionotropic receptors. Using RT-PCR, we conducted the first exhaustive comparison of olfactory gene expression between larvae and adults in a lepidopteran species. All the 127 candidate olfactory genes were profiled for expression in male and female adult antennae and in caterpillar antennae and maxillary palps. We found that caterpillars expressed a smaller set of olfactory genes than adults, with a large overlap between these two developmental stages. Two binding proteins appeared to be larvae-specific and two others were adult-specific. Interestingly, comparison between caterpillar antennae and maxillary palps revealed numerous organ-specific transcripts, suggesting the complementary involvement of these two organs in larval chemosensory detection. Adult males and females shared the same set of olfactory transcripts, except two male-specific candidate pheromone receptors, two male-specific and two female-specific odorant-binding proteins. This study identified transcripts that may be important for sex-specific or developmental stage-specific chemosensory behaviors