At-sea movements of wedge-tailed shearwaters during and outside the breeding season from four colonies in New Caledonia

International audienceThe wedge-tailed shearwater (WTS) population of New Caledonia is one of the largest in the world, yet its biology and foraging ecology are poorly known. We studied WTS from 4 colonies in New Caledonia. We examined foraging behaviour and habitats using GPS receivers and light sensors during and outside the breeding season, respectively, and compared our findings with those from other WTS populations worldwide. During breeding, New Caledonian WTS alternated short foraging trips close to the colony over the lagoon, or off the reef edge, with longer trips over distant, deep waters. Whereas neighboring colonies overlapped at sea, especially during short trips, there was a clear separation of foraging zones between the pairs of colonies located in the southern versus northwestern parts of New Caledonia. Although WTS actively foraged and commuted to foraging zones during the day, they mainly returned to the colony or rested at night, indicating that they feed mainly during the day. Active foraging did not take place in more productive areas, suggesting that it may instead be related to the presence of sub-surface predators. Outside the breeding season, birds from 3 colonies had similar trans-equatorial migratory behaviour. All left New Caledonia at the same time of the year with a fast, northeasterly movement and wintered over deep waters in the same sector of the northwestern tropical Pacific Ocean. At overwintering sites, they spent most of their non-foraging time presumably sitting on the water, especially at night, making a slow westward movement before returning to New Caledonia. WTS from New Caledonia forage over warm, oligotrophic deep waters throughout their life cycle, and the species appears to have a flexible foraging strategy adapted to the various environmental conditions encountered across its wide tropical range

Automorphismes projectifs etpolynômes binaires irréductibles

The first part is devoted to the enumeration of the orbits of the irreducible binary polynomials (ibp) under the action of the automorphism group of the projective line P1 over GF(2) (for a given degree).The second part gives quadratic and cubic transformations allowing to construct new ibps from given ones.The third part is an interpretation of these transformations using elliptic curves. New sequences were recorded in the OEIS.The work prolongates the results of Carlitz, Meyn , Gotz, Wiedeman...La première partie est consacrée à l'énumération des orbites des polynômes binaires irréductibles (ibp) sous l'action du groupe d'automorphismes de la droite projective P1 sur GF(2) (pour un degré donné).La deuxième partie donne des transformations quadratiques et cubiques permettant de construire de nouvelles ipp à partir d'ips données.La troisième partie est une interprétation de ces transformations à l'aide de courbes elliptiques.De nouvelles séquences ont été enregistrées dans l'OEIS.L'ouvrage prolonge les résultats de Carlitz, Meyn, Gotz, Wiedeman..

Automorphismes projectifs etpolynômes binaires irréductibles

The first part is devoted to the enumeration of the orbits of the irreducible binary polynomials (ibp) under the action of the automorphism group of the projective line P1 over GF(2) (for a given degree).The second part gives quadratic and cubic transformations allowing to construct new ibps from given ones.The third part is an interpretation of these transformations using elliptic curves. New sequences were recorded in the OEIS.The work prolongates the results of Carlitz, Meyn , Gotz, Wiedeman...La première partie est consacrée à l'énumération des orbites des polynômes binaires irréductibles (ibp) sous l'action du groupe d'automorphismes de la droite projective P1 sur GF(2) (pour un degré donné).La deuxième partie donne des transformations quadratiques et cubiques permettant de construire de nouvelles ipp à partir d'ips données.La troisième partie est une interprétation de ces transformations à l'aide de courbes elliptiques.De nouvelles séquences ont été enregistrées dans l'OEIS.L'ouvrage prolonge les résultats de Carlitz, Meyn, Gotz, Wiedeman..

Food and space use strategies oceanic by two species of Procellariidae in New Caledonia : Application to conservation

Les stratégies de recherche alimentaire chez les Procellariidés (puffins et pétrels) dépendent de nombreux facteurs environnementaux et intrinsèques et leur connaissance est souvent à la base des mesures de conservation de ces espèces en mer. Leur étude permet également d’apporter des informations sur la présence et l’abondance d’espèces associées à leurs zones d’alimentation. Cette thèse vise à apporter des éléments de connaissance sur les déplacements et l’utilisation de l’espace océanique et des ressources trophiques par deux espèces de Procellariidés se reproduisant en Nouvelle-Calédonie : le puffin fouquet (Ardenna pacifica) et le pétrel de Tahiti (Pseudobulweria rostrata). Pour cela, nous avons combiné l’étude de leurs déplacements en mer par suivi GPS avec l’étude de leur régime alimentaire par l’analyse d’isotopes stables et le barcoding ADN.Les principales zones d’alimentation et le type de proies consommées ont été identifiés pour chaque espèce et chaque population pendant leur période de reproduction. Les mécanismes de ségrégation intra-spécifique entre les différentes populations et de ségrégation interspécifique permettant la cohabitation des deux espèces ont été mis en évidence. Différents facteurs environnementaux déterminant les stratégies d’alimentation des espèces ont également été mis en évidence. Enfin, tenant compte de ces différents paramètres et interactions au sein et entre espèces, cette thèse a visé à déterminer des zones océaniques hauturières à fort enjeux de conservation, afin notamment de fournir des éléments d’aide à la décision aux gestionnaires du Parc Naturel de la Mer de Corail, la 4ème plus grande aire marine protégée de la Planète.Foraging strategies of Procellariidae (shearwaters and petrels) depend on many environmental and intrinsic factors, and their knowledge is often the basis for conservation measures for these species at sea. Their study also provides information on the presence and abundance of species associated with their feeding grounds. This thesis aims to provide information on the movements and use of ocean space and trophic resources by two species of Procellariidae breeding in New Caledonia: the wedge-tailed shearwater (Ardenna pacifica) and the Tahiti petrel (Pseudobulweria rostrata). In this purpose, we combined the study of their at-sea movements by GPS tracking with the study of their diet by stable isotope analysis and DNA barcoding.The main foraging areas and the type of prey consumed were identified for each species and each population during their breeding period. The mechanisms of intraspecific segregation between the different populations and interspecific segregation allowing the cohabitation of the two species were highlighted. Different environmental factors determining the foraging strategies of the species were also revealed. Finally, taking into account these different parameters and interactions within and between species, this thesis aimed to determine oceanic areas with high conservation stakes, in order to provide elements of decision support to the managers of the Coral Sea Natural Park, the 4th largest marine protected area of the Planet

Sur différentes familles de polynômes binaires irréductibles

International audienceUsing a natural action of the permutation group S3 on the set of irreducible polynomials, we attach to each subgroup of S3 the family of its invariant polynomials. Enumeration formulas for the trivial subgroup and for one transposition subgroup were given by Gauss (for prime fields) [1] and Carlitz (for all finite base fields) [2]. Respectively, they allow to enumerate all irreducible and self reciprocal irreducible polynomials. In our context, the last remaining case concerned the alternating subgroup A3. We give here the corresponding enumeration formula restricted to F2 base field. We wish this will give an interesting basis for subsequent developments analogous to those of Meyn [3] and Cohen [4]

Automorphismes projectifs et polynômes binaires irréductibles

Cette thèse porte sur l'étude de certaines propriétés structurelles de l'ensemble des polynômes irréductibles à coefficients dans F2. La première partie classifie ces polynômes par rapport à l'action du groupe des automorphismes de la droite projective P1(F2), à savoir PGL2(F2) S3. Nous btenons quatre familles de polynômes invariants par l'action des quatre sous-groupes non triviaux de S3, ce qui généralise la notion de polynôme réciproque. De plus, nous donnons une formule de dénombrement qui complète celle de Carlitz (qui a traité le cas réciproque). Dans la seconde partie, nous donnons des transformations permettant de générer nos polynômes invariants ainsi que le théorème général décrivant leur action précise sur les polynômes irréductibles. Cela donne deux partitions différentes par des relations simples sur leurs coefficients. Nous proposons également des moyens de construire des suites infinies explicites d'irréductibles invariants en généralisant ce qui existait pour les réciproques. Dans la troisième partie, nous étudions plus en détail nos transformations. En particulier, nous retrouvons deux d'entre elles au travers d'opérations sur les points de deux courbes elliptiques.This Ph.D. is a study of some structural properties of the set of irreducible polynomials with coefficients in F2. The first part classify these polynomials under the action of the automorphisms group of the projective line P1(F2), i.e. PGL2(F2) S3. We obtain four families of invariant polynomials under each non trivial subgroup of S3, which generalize the notion of self-reciprocal polynomials. Moreover, we give an enumeration formula that completes Carlitz' one (which concerns the self-reciprocal polynomials). In the second part, we give transformations that generate our invariant polynomials and the general theorem describing their action on the irreducible polynomials. That gives two different partitions by easy relations on their coefficients. We also propose ways to construct infinite sequences of irreducible invariant polynomials, generalizing what was known for self-reciprocal polynomials. In the third part, we study more deeply our transformations. In particular, we show that we can find two of them through operations on the points of two elliptic curves.ROUEN-BU Sciences Madrillet (765752101) / SudocSudocFranceF

Transformations sur les polynômes binaires irréductibles

International audienceUsing the natural action of GL2(F2) S3 over F2[X], one can define different classes of polynomials strongly analogous to selfreciprocal irreducible polynomials. We give transformations to construct polynomials of each kind of invariance and we deal with the question of explicit infinite sequences of invariant irreducible polynomials in F2[X]. We generalize results obtained by Varshamov, Wiedemann, Meyn and Cohen and we give sequences of invariant irreducible polynomials. Moreover we explain what happens when the given constructions fail. We also give a result on the order of the polynomials of one of the classes: the alternate irreducible polynomials

HSF1/HSF2 heterotrimer and c-jun/Fra2 heterodimer transactivate the clusterin gene upon proteasome inhibition

Communication orale présentée par Loison F

In situ and time-resolved infrared detection of the reactivity induced by electrons in polymer films

International audienceThe real time and in situ analysis of chemical reactions such as polymerization reactions, polymer degradation, and oxidation of polymers is of utmost importance. Surprisingly, only few experimental tools allowing this are available. To bridge this gap, we have developed a new experimental setup coupling a 60 keV electron gun with an infrared spectrometer operating in the mid-IR region (800-4000 cm 1) and associated with the rapid scan mode. The measurements are performed using the infrared reflection absorption spectroscopy approach. We worked here with 0.5–25 ms pulses for which the dose per pulse ranges from 4 to 200 kGy. Combining pulse electrons with rapid scan analysis enables performing experiments with a time resolution of 80 ms (and above). Therefore, this new platform can, for instance, give direct insights into reaction mechanisms at stake during the degradation of polymers. First results on a bisphenol A polycarbonate irradiated under vacuum enabling the validation of this new setup and also the recording of time-resolved spectra are presented. Reaction mechanisms are then proposed

Trans-stereospecific polymerization of butadiene and random copolymerization with styrene using borohydrido neodymium/magnesium dialkyl catalysts

11 pagesInternational audienceThe combination of a neodymium borohydride, Nd(BH4)3(THF)3 (1) or Cp*Nd(BH4)2(THF)x (2), with MgnBuEt (BEM), affords an efficient and highly selective (up to 96.7% 1,4-trans) catalyst for butadiene polymerization. In the presence of excesses of Mg co-catalyst, polymer chain transfer takes place between neodymium and magnesium, and significant amounts of 1,2-units are observed. When considered for butadiene-styrene statistical copolymerization, the catalytic system based on 2 showed a good ability to produce poly[(1,4-trans-butadiene)-co-styrene)], with strong impact of the Mg/Nd ratio on the yield and on the copolymer microstructure, including the percentage of inserted styrene (up to 16.9 mol%). Whatever the co-monomers concentration the polybutadiene backbone remained 1,4-trans. The precise microstructure of the polymers and copolymers was thoroughly analyzed by means of high resolution NMR spectroscopy (900 MHz) and MALDI-ToF spectrometry