Odyssey 2 : A mission toward Neptune and Triton to test General Relativity

Odyssey 2 will be proposed in December 2010 for the next call of M3 missions for Cosmic Vision 2015-2025. This mission, under a Phase 0 study performed by CNES, will aim at Neptune and Triton. Two sets of objectives will be pursued. The first one is to perform a set of gravitation experiments at the Solar System scale. Experimental tests of gravitation have always shown good agreement with General Relativity. There are however drivers to continue testing General Relativity, and to do so at the largest possible scales. From a theoretical point of view, Einstein's theory of gravitation shows inconsistencies with a quantum description of Nature and unified theories predict deviations from General Relativity. From an observational point of view, as long as dark matter and dark energy are not observed through other means than their gravitational effects, they can be considered as a manifestation of a modification of General Relativity at cosmic scales. The scientific objectives are to: (i) test the gravitation law at the Solar System scale; (ii) measure the Eddington parameter; and (iii) investigate the navigation anomalies during fly-bys. To fulfil these objectives, the following components are to be on board the spacecraft: (i) the Gravity Advanced Package (GAP), which is an electrostatic accelerometer to which a rotating stage is added; (ii) radio-science; (iii) laser ranging, to improve significantly the measure of the Eddington parameter. The second set of objectives is to enhance our knowledge of Neptune and Triton. Several instruments dedicated to planetology are foreseen: camera, spectrometer, dust and particle detectors, and magnetometer. Depending on the ones kept, the mission could provide information on the gravity field, the atmosphere and the magnetosphere of the two bodies as well as on the surface geology of Triton and on the nature of the planetary rings around Neptune.Comment: 61st International Astronautical Congress (Prague, Czech Republic - September 2010), 7 page

Reduced phase space of heat-carrying acoustic phonons in single-crystalline InTe

Chalcogenide semiconductors and semimetals are a fertile class of efficient thermoelectric materials, which, in most cases, exhibit very low lattice thermal conductivity κph despite lacking a complex crystal structure such as the tetragonal binary compound InTe. Our measurements of κph(T) in single-crystalline InTe along the c axis show that κph exhibits a smooth temperature dependence upon cooling to about 50 K, the temperature below which a strong rise typical for dielectric compounds is observed. Using a combination of first-principles calculations, inelastic neutron scattering (INS), and low-temperature specific heat and transport properties measurements on single-crystalline InTe, we show that the phonon spectrum exhibits well-defined acoustic modes, the energy dispersions of which are constrained to low energies due to distributions of dispersionless, optical modes, which are responsible for a broad double peak structure in the low-temperature specific heat. The latter are assigned to the dynamics of In+ cations in tunnels formed by edge-sharing (In3+Te42−)− tetrahedra chains, the atomic thermal displacement parameters of which, probed as a function of temperature by means of single-crystal x-ray diffraction, suggest the existence of a complex energy potential. Indeed, the In+-weighted optical modes are not observed by INS, which is ascribed to the anharmonic broadening of their energy profiles. While the low κph value of 1.2Wm−1K−1 at 300 K originates from the limited energy range available for acoustic phonons, we show that the underlying mechanism is specific to InTe and argue that it is likely related to the presence of local disorder induced by the In+ sit

Aversive Learning in Honeybees Revealed by the Olfactory Conditioning of the Sting Extension Reflex

Invertebrates have contributed greatly to our understanding of associative learning because they allow learning protocols to be combined with experimental access to the nervous system. The honeybee Apis mellifera constitutes a standard model for the study of appetitive learning and memory since it was shown, almost a century ago, that bees learn to associate different sensory cues with a reward of sugar solution. However, up to now, no study has explored aversive learning in bees in such a way that simultaneous access to its neural bases is granted. Using odorants paired with electric shocks, we conditioned the sting extension reflex, which is exhibited by harnessed bees when subjected to a noxious stimulation. We show that this response can be conditioned so that bees learn to extend their sting in response to the odorant previously punished. Bees also learn to extend the proboscis to one odorant paired with sugar solution and the sting to a different odorant paired with electric shock, thus showing that they can master both appetitive and aversive associations simultaneously. Responding to the appropriate odorant with the appropriate response is possible because two different biogenic amines, octopamine and dopamine subserve appetitive and aversive reinforcement, respectively. While octopamine has been previously shown to substitute for appetitive reinforcement, we demonstrate that blocking of dopaminergic, but not octopaminergic, receptors suppresses aversive learning. Therefore, aversive learning in honeybees can now be accessed both at the behavioral and neural levels, thus opening new research avenues for understanding basic mechanisms of learning and memory

E-β-Ocimene, a Volatile Brood Pheromone Involved in Social Regulation in the Honey Bee Colony (Apis mellifera)

Background: In honey bee colony, the brood is able to manipulate and chemically control the workers in order to sustain their own development. A brood ester pheromone produced primarily by old larvae (4 and 5 days old larvae) was first identified as acting as a contact pheromone with specific effects on nurses in the colony. More recently a new volatile brood pheromone has been identified: E-β-ocimene, which partially inhibits ovary development in workers. [br/] Methodology and Principal Finding: Our analysis of E-β-ocimene production revealed that young brood (newly hatched to 3 days old) produce the highest quantity of E-b-ocimene relative to their body weight. By testing the potential action of this molecule as a non-specific larval signal, due to its high volatility in the colony, we demonstrated that in the presence of E-β-ocimene nest workers start to forage earlier in life, as seen in the presence of real brood. [br/] Conclusions/Significance: In this way, young larvae are able to assign precedence to the task of foraging by workers in order to increase food stores for their own development. Thus, in the complexity of honey bee chemical communication, E-β- ocimene, a pheromone of young larvae, provides the brood with the means to express their nutritional needs to the workers

Reappraising Social Insect Behavior through Aversive Responsiveness and Learning

Background: The success of social insects can be in part attributed to their division of labor, which has been explained by a response threshold model. This model posits that individuals differ in their response thresholds to task-associated stimuli, so that individuals with lower thresholds specialize in this task. This model is at odds with findings on honeybee behavior as nectar and pollen foragers exhibit different responsiveness to sucrose, with nectar foragers having higher response thresholds to sucrose concentration. Moreover, it has been suggested that sucrose responsiveness correlates with responsiveness to most if not all other stimuli. If this is the case, explaining task specialization and the origins of division of labor on the basis of differences in response thresholds is difficult. Methodology: To compare responsiveness to stimuli presenting clear-cut differences in hedonic value and behavioral contexts, we measured appetitive and aversive responsiveness in the same bees in the laboratory. We quantified proboscis extension responses to increasing sucrose concentrations and sting extension responses to electric shocks of increasing voltage. We analyzed the relationship between aversive responsiveness and aversive olfactory conditioning of the sting extension reflex, and determined how this relationship relates to division of labor. Principal Findings: Sucrose and shock responsiveness measured in the same bees did not correlate, thus suggesting that they correspond to independent behavioral syndromes, a foraging and a defensive one. Bees which were more responsiv

<scp>ReSurveyEurope</scp>: A database of resurveyed vegetation plots in Europe

AbstractAimsWe introduce ReSurveyEurope — a new data source of resurveyed vegetation plots in Europe, compiled by a collaborative network of vegetation scientists. We describe the scope of this initiative, provide an overview of currently available data, governance, data contribution rules, and accessibility. In addition, we outline further steps, including potential research questions.ResultsReSurveyEurope includes resurveyed vegetation plots from all habitats. Version 1.0 of ReSurveyEurope contains 283,135 observations (i.e., individual surveys of each plot) from 79,190 plots sampled in 449 independent resurvey projects. Of these, 62,139 (78%) are permanent plots, that is, marked in situ, or located with GPS, which allow for high spatial accuracy in resurvey. The remaining 17,051 (22%) plots are from studies in which plots from the initial survey could not be exactly relocated. Four data sets, which together account for 28,470 (36%) plots, provide only presence/absence information on plant species, while the remaining 50,720 (64%) plots contain abundance information (e.g., percentage cover or cover–abundance classes such as variants of the Braun‐Blanquet scale). The oldest plots were sampled in 1911 in the Swiss Alps, while most plots were sampled between 1950 and 2020.ConclusionsReSurveyEurope is a new resource to address a wide range of research questions on fine‐scale changes in European vegetation. The initiative is devoted to an inclusive and transparent governance and data usage approach, based on slightly adapted rules of the well‐established European Vegetation Archive (EVA). ReSurveyEurope data are ready for use, and proposals for analyses of the data set can be submitted at any time to the coordinators. Still, further data contributions are highly welcome.</jats:sec

The SIB Swiss Institute of Bioinformatics' resources: focus on curated databases

The SIB Swiss Institute of Bioinformatics (www.isb-sib.ch) provides world-class bioinformatics databases, software tools, services and training to the international life science community in academia and industry. These solutions allow life scientists to turn the exponentially growing amount of data into knowledge. Here, we provide an overview of SIB's resources and competence areas, with a strong focus on curated databases and SIB's most popular and widely used resources. In particular, SIB's Bioinformatics resource portal ExPASy features over 150 resources, including UniProtKB/Swiss-Prot, ENZYME, PROSITE, neXtProt, STRING, UniCarbKB, SugarBindDB, SwissRegulon, EPD, arrayMap, Bgee, SWISS-MODEL Repository, OMA, OrthoDB and other databases, which are briefly described in this article

Structure sociale et stratégie de reproduction chez Cardiocondyla elegans

Cardiocondyla elegans is a Mediterranean ant that is present in the Loire River sides. The aims of this thesis were to have a better understanding of its biology, reproductive strategies as well as the characteristics of its environment. We then used an integrated framework: pedology, ecology and botanic for the habitat and environment characterization, genetic and ethology to determine the genetic structure of nests and populations and to investigate behaviour of sexual individuals.C. elegans nests consist of a 40 cm deep vertical pipe connecting a dozen of chambers. In Loire River habitats, C. elegans was found only in stable alluvial deposits. The composition of these sediments are from importance for the survival of the nests. They provide constant temperature in the deepest chambers; even in the hottest period of the summer, temperature remains less than 30°C with few daily variations. As the sediments containing less than 60% fine sand, the habitat can resist to foods and these rises in the watertable can retain an air pocket needed for ants to survive. Our study on spatial distribution of colonies along two successive years reveals that 40% of them disappear because of the winter conditions. Nonetheless, numerous winged females survive and found new nests. C. elegans generally attains a density of 1 nest per m2 in Loire riverine habitat during the summer. As this ant lives in a patchy environment, colonies compete for space, and we found that they finally distribute regularly. Intra-specific competition is probably one of the reasons why less than 1% of the new queen success in nest foundation.From July to September, mature nests produce sexual individuals. C. elegans develop regular winged female and more peculiar wingless ergatoid males. Contrary to other ergatoid males in Cardiocondyla genus, males of C. elegans are mutually tolerant. We confirmed monogyny for this species with one queen and about 200 workers per nest. The mean numbers of ergatoid males and winged females during the reproductive period are respectively 5.3 and 76.6. Usually, the mother queen was mated by several males. Individuals of the same nest came from about 4.5 different patrilines. Analysis of the population genetic structure indicates that 30% of the copulations involve unrelated partners. We also founded numerous alien sexuals inside the nests. Foreign sexuals inside nests of a monogynous ant species is puzzling and ask questions on the reproductive strategies of C. elegans. In behavioural tests of adoption, host workers always accept ergatoid males to enter their nest whereas they repel and attack winged females. The presence of alien winged females inside nests can be explained by the active carrying behaviour of some workers in the field. These workers carry winged females from a nest to another one and host workers do not develop aggressive behaviour in these conditions. Exchanges of sexual individuals can reduce inbreeding depression in the population and then avoid diploid males' problems. That also provides more genetic variability to resist in case of major environmental changes.Then, our study show an original reproductive strategy for C. elegans, describes here for the first time. We also show that C. elegans is the only ant species adapted to early stages of stabilization of the alluvial deposits. Thus, along with the local flora, C. elegans can be used as an indicator to characterize the morphological evolution of the secondary channels of the Loire River.Cardiocondyla elegans est une fourmi méditerranéenne que l'on retrouve sur les bords de Loire. Cette espèce possède quelques particularités, comme par exemple avoir des mâles aptères. L'objectif de cette thèse était de comprendre sa biologie, ses stratégies de reproduction ainsi que les caractéristiques de son environnement. Pour cela, nous avons utilisé une approche multidisciplinaire, menant des études de pédologie, d'écologie et de botanique (caractérisation de l'habitat et de l'environnement), ainsi que de génétique et d'éthologie (structure génétique des nids et des populations, détermination du génotype et comportement des sexués).Après avoir confirmé génétiquement la monogynie de cette espèce (une seule reine entourée d'environ 200 ouvrières), nous nous sommes attachés à analyser l'habitat de C. elegans. Le nid est creusé dans le sol jusqu'à 40 cm de profondeur. Il est composé, comme celui de nombreuses autres espèces, d'un conduit vertical reliant une dizaine de chambres superposées. En milieu ligérien, C. elegans est retrouvée uniquement sur les grèves en fixation. Nous avons montré que la composition des sédiments de ces grèves était importante pour la survie de cette fourmi. Durant l'été, elle permet dans les chambres les plus profondes, de conserver une température constante inférieure à 30°C avec de très faibles variations quotidiennes. Durant les crues, les sédiments composés de moins de 60% de sable, ne sont que très peu entraînés par le courant (grèves « fixées »). De plus ils permettent, lors de la remontée de la nappe alluviale, la création de poches d'air nécessaires à la survie des fourmis.L'étude de la répartition spatiale des nids au cours des années nous a révélé que 40% des nids disparaissent d'une année sur l'autre suite aux conditions hivernales. Cependant, suffisamment d'individus sexués, en l'occurrence des femelles fécondées, survivent pour fonder de nouveaux nids. La population étudiée de C. elegans sur les bords de Loire montre une forte densité avoisinant 1 nid/m2. Les grèves fixées étant des environnements morcelés, les nids entrent en compétition pour l'espace et se distribuent de façon régulière. Ainsi, moins de 1% des femelles réussissent à fonder de nouveaux nids.De Juillet à Septembre, les nids matures produisent des individus sexués. Alors que les femelles sont ailées, C. elegans possède une particularité par rapport aux autres fourmis : elle ne produit que des mâles ergatoïdes (sans ailes) tolérants entre eux. Nous avons déterminé que lors de la période de reproduction, les nids contenaient en moyenne 5,3 mâles ergatoïdes et 76,6 femelles ailées. La reine est généralement fécondée par plusieurs mâles. Ainsi les individus du nid sont issus de la même mère mais peuvent avoir des pères différents (en moyenne 4,5 fratries par nid).En analysant la structure génétique des populations nous pouvons dire que 30% des accouplements impliquent des individus non apparentés. Ce fait est du à la présence de nombreux sexués étrangers à l'intérieur des nids. La présence d'individus étrangers dans des colonies monogynes est singulière et nous a amené à nous interroger sur les stratégies de reproduction de C. elegans. Des tests comportementaux nous ont permis de mettre en évidence que les mâles étaient toujours acceptés lorsqu'ils tentaient de pénétrer dans une nouvelle colonie contrairement aux femelles ailées qui sont systématiquement attaquées. La présence de femelles ailées dans des nids étrangers s'explique par leur transport par des ouvrières, un comportement que nous avons observé sur le terrain en période de reproduction. Ces échanges de sexués pourraient permettre de diminuer la consanguinité à l'intérieur de la population, évitant ainsi la production de mâles diploïdes (stériles) et procurer une meilleure résistance de la population en cas de changements environnementaux.L'étude de cette fourmi nous a permis de mettre en évidence une stratégie de reproduction originale, décrite ici pour la première fois. Notre étude révèle également que C. elegans est la seule espèce de fourmis à être adaptée aux conditions environnementales des grèves en fixation. La seule présence de cet organisme, au même titre que certaines espèces végétales, permet de caractériser une étape de l'évolution morphologique des chenaux secondaires de la Loire

Structure sociale et stratégie de reproduction chez Cardiocondyla elegans

Cardiocondyla elegans is a Mediterranean ant that is present in the Loire River sides. The aims of this thesis were to have a better understanding of its biology, reproductive strategies as well as the characteristics of its environment. We then used an integrated framework: pedology, ecology and botanic for the habitat and environment characterization, genetic and ethology to determine the genetic structure of nests and populations and to investigate behaviour of sexual individuals. C. elegans nests consist of a 40 cm deep vertical pipe connecting a dozen of chambers. In Loire River habitats, C. elegans was found only in stable alluvial deposits. The composition of these sediments are from importance for the survival of the nests. They provide constant temperature in the deepest chambers; even in the hottest period of the summer, temperature remains less than 30C with few daily variations. As the sediments containing less than 60% fine sand, the habitat can resist to foods and these rises in the watertable can retain an air pocket needed for ants to survive. Our study on spatial distribution of colonies along two successive years reveals that 40% of them disappear because of the winter conditions. Nonetheless, numerous winged females survive and found new nests. C. elegans generally attains a density of 1 nest per m2 in Loire riverine habitat during the summer. As this ant lives in a patchy environment, colonies compete for space, and we found that they finally distribute regularly. Intra-specific competition is probably one of the reasons why less than 1% of the new queen success in nest foundation. From July to September, mature nests produce sexual individuals. C. elegans develop regular winged female and more peculiar wingless ergatoid males. Contrary to other ergatoid males in Cardiocondyla genus, males of C. elegans are mutually tolerant. We confirmed monogyny for this species with one queen and about 200 workers per nest. The mean numbers of ergatoid males and winged females during the reproductive period are respectively 5.3 and 76.6. Usually, the mother queen was mated by several males. Individuals of the same nest came from about 4.5 different patrilines. Analysis of the population genetic structure indicates that 30% of the copulations involve unrelated partners. We also founded numerous alien sexuals inside the nests. Foreign sexuals inside nests of a monogynous ant species is puzzling and ask questions on the reproductive strategies of C. elegans. In behavioural tests of adoption, host workers always accept ergatoid males to enter their nest whereas they repel and attack winged females. The presence of alien winged females inside nests can be explained by the active carrying behaviour of some workers in the field. These workers carry winged females from a nest to another one and host workers do not develop aggressive behaviour in these conditions. Exchanges of sexual individuals can reduce inbreeding depression in the population and then avoid diploid males' problems. That also provides more genetic variability to resist in case of major environmental changes. Then, our study show an original reproductive strategy for C. elegans, describes here for the first time. We also show that C. elegans is the only ant species adapted to early stages of stabilization of the alluvial deposits. Thus, along with the local flora, C. elegans can be used as an indicator to characterize the morphological evolution of the secondary channels of the Loire River.Cardiocondyla elegans est une fourmi méditerranéenne que l'on retrouve sur les bords de Loire. Cette espèce possède quelques particularités, comme par exemple avoir des mâles aptères. Les objectifs de cette thèse étaient de comprendre sa biologie, ses stratégies de reproduction ainsi que les caractéristiques de son environnement. Pour cela, nous avons utilisé une approche multidisciplinaire, menant des études de pédologie, d'écologie et de botanique (caractérisation de l'habitat et de l'environnement), ainsi que de génétique et d'éthologie (structure génétique des nids et des populations, détermination du génotype et comportement des sexués). Après avoir confirmé génétiquement la monogynie de cette espèce (une seule reine entourée d'environ 200 ouvrières), nous nous sommes attachés à analyser l'habitat de C. elegans. Le nid est creusé dans le sol jusqu'à 40 cm de profondeur. Il est composé, comme celui de nombreuses autres espèces, d'un conduit vertical reliant une dizaine de chambres superposées. En milieu ligérien, C. elegans se retrouve uniquement sur les grèves en voie de fixation. Nous avons montré que la composition des sédiments de ces grèves était importante pour la survie de cette fourmi. Durant l'été, elle permet dans les chambres les plus profondes, de conserver une température constante inférieure à 30C avec de très faibles variations quotidiennes. Durant les crues, les sédiments composés de moins de 60% de sable, ne sont que très peu entraînés par le courant (grèves " fixées "). De plus ils permettent, lors de la remontée de la nappe alluviale, la création de poches d'air nécessaires à la survie des fourmis. L'étude de la répartition spatiale des nids au cours des années nous a révélé que 40% des nids disparaissent d'une année sur l'autre suite aux conditions hivernales. Cependant, suffisamment d'individus sexués, en l'occurrence des femelles fécondées, survivent pour fonder de nouveaux nids. La population étudiée de C. elegans sur les bords de Loire montre une forte densité avoisinant 1 nid/m2. Les grèves fixées étant des environnements morcelés, les nids entrent en compétition pour l'espace et se distribuent de façon régulière. Ainsi, moins de 1% des femelles réussissent à fonder de nouveaux nids. De Juillet à Septembre, les nids matures produisent des individus sexués. Alors que les femelles sont ailées, C. elegans possède une particularité par rapport aux autres fourmis : elle ne produit que des mâles ergatoïdes (sans ailes) tolérants entre eux. Nous avons déterminé que lors de la période de reproduction, les nids contenaient en moyenne 5,3 mâles ergatoïdes et 76,6 femelles ailées. La reine est généralement fécondée par plusieurs mâles. Ainsi les individus du nid sont issus de la même mère mais peuvent avoir des pères différents (en moyenne 4,5 fratries par nid). En analysant la structure génétique des populations nous pouvons dire que 30% des accouplements impliquent des individus non apparentés. Ce fait est dû à la présence de nombreux sexués étrangers à l'intérieur des nids. La présence d'individus étrangers dans des colonies monogynes est singulière et nous a amené à nous interroger sur les stratégies de reproduction de C. elegans. Des tests comportementaux nous ont permis de mettre en évidence que les mâles étaient toujours acceptés lorsqu'ils tentaient de pénétrer dans une nouvelle colonie, contrairement aux femelles ailées qui sont systématiquement attaquées. La présence de femelles ailées dans des nids étrangers est liée à leur transport par des ouvrières, un comportement que nous avons observé sur le terrain en période de reproduction. Ces échanges de sexués pourraient permettre de diminuer la consanguinité à l'intérieur de la population, évitant ainsi la production de mâles diploïdes (stériles) et procurer une meilleure résistance de la population en cas de changements environnementaux. L'étude de cette fourmi nous a permis de mettre en évidence une stratégie de reproduction originale, décrite ici pour la première fois. Notre étude révèle également que C. elegans est la seule espèce de fourmis à être adaptée aux conditions environnementales des grèves en fixation. La seule présence de cet organisme, au même titre que certaines espèces végétales, permet de caractériser une étape de l'évolution morphologique des chenaux secondaires de la Loire.TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF