PISCO2: the new speckle camera of the Nice 76-cm refractor

We present the new speckle camera PISCO2 made in 2010-2012, for the 76-cm refractor of C\^ote d'Azur Observatory. It is a focal instrument dedicated to the observation of visual binary stars using high angular resolution speckle interferometry techniques to partly overcome the degradation caused by the atmospheric turbulence. Fitted with an EMCCD detector, PISCO2 allows the acquisition of short exposure images that are processed in real time by our specially designed software. Two Risley prisms are used for correcting the atmospheric dispersion. All optical settings are remotely controlled. We have already been able to observe faint, close binary stars with angular separations as small as 0".16, and visual magnitudes of about 16. We also have measured some particularly difficult systems with a magnitude difference between the two components of about 4 magnitudes. This level of performance is very promising for the detection and study of large sets of yet unknown (or partly measured) binaries with close separation and/or large magnitude difference.Comment: 13 pages, 12 figure

Modeling and control of flow with dynamical boundary actions

International audienceIn this paper a flow inside a pipe is modeled by a hyperbolic system (written in terms of a partial differential equation). One boundary condition is given by the coupling with a finite-dimensional dynamic model of heating column and a static modeling of ventilator. Then, the classical finite-dimensional technique is applied for the linearization of first order hyperbolic systems with dynamics associated to the boundary conditions. The discretization of the infinite-dimensional system is used and an augmented discrete linear system with dimension depending on the step size of discretization in space is obtained. The results are illustrated on simulations considering a Poiseuille flow experimental setup

Thermodesulfatator atlanticus sp. nov., a thermophilic, chemolithoautotrophic, sulfate-reducing bacterium isolated from a Mid-Atlantic Ridge hydrothermal vent.

International audienceA novel, strictly anaerobic, thermophilic, sulfate-reducing bacterium, designated strain AT1325(T), was isolated from a deep-sea hydrothermal vent at the Rainbow site on the Mid-Atlantic Ridge. This strain was subjected to a polyphasic taxonomic analysis. Cells were Gram-negative motile rods (approximately 2.4 x 0.6 microm) with a single polar flagellum. Strain AT1325(T) grew at 55-75 degrees C (optimum, 65-70 degrees C), at pH 5.5-8.0 (optimum, 6.5-7.5) and in the presence of 1.5-4.5 % (w/v) NaCl (optimum, 2.5 %). Cells grew chemolithoautotrophically with H2 as an energy source and SO4(2-) as an electron acceptor. Alternatively, the novel isolate was able to use methylamine, peptone or yeast extract as carbon sources. The dominant fatty acids (>5 % of the total) were C(16 : 0), C(18 : 1)omega7c, C(18 : 0) and C(19 : 0) cyclo omega8c. The G+C content of the genomic DNA of strain AT1325(T) was 45.6 mol%. Phylogenetic analyses based on 16S rRNA gene sequences placed strain AT1325(T) within the family Thermodesulfobacteriaceae, in the bacterial domain. Comparative 16S rRNA gene sequence analysis indicated that strain AT1325(T) belonged to the genus Thermodesulfatator, sharing 97.8 % similarity with the type strain of Thermodesulfatator indicus, the unique representative species of this genus. On the basis of the data presented, it is suggested that strain AT1325(T) represents a novel species of the genus Thermodesulfatator, for which the name Thermodesulfatator atlanticus sp. nov. is proposed. The type strain is AT1325(T) (=DSM 21156(T)=JCM 15391(T))

Flame Describing Function analysis of spinning and standing modes in an annular combustor and comparison with experiments

This article reports a numerical analysis of combustion instabilities coupled by a spinning mode or a standing mode in an annular combustor. The method combines an iterative algorithm involving a Helmholtz solver with the Flame Describing Function (FDF) framework. This is applied to azimuthal acoustic coupling with combustion dynamics and is used to perform a weakly nonlinear stability analysis yielding the system response trajectory in the frequency-growth rate plane until a limit cycle condition is reached. Two scenarios for mode type selection are tentatively proposed. The first is based on an analysis of the frequency growth rate trajectories of the system for different initial solutions. The second consid- ers the stability of the solutions at limit cycle. It is concluded that a criterion combining the stability analysis at the limit cycle with the trajectory analysis might best define the mode type at the limit cy- cle. Simulations are compared with experiments carried out on the MICCA test facility equipped with 16 matrix burners. Each burner response is represented by means of a global FDF and it is considered that the spacing between burners is such that coupling with the mode takes place without mutual interac- tions between adjacent burning regions. Depending on the nature of the mode being considered, two hypotheses are made for the FDFs of the burners. When instabilities are coupled by a spinning mode, each burner features the same velocity fluctuation level implying that the complex FDF values are the same for all burners. In case of a standing mode, the sixteen burners feature different velocity fluctua- tion amplitudes depending on their relative position with respect to the pressure nodal line. Simulations retrieve the spinning or standing nature of the self-sustained mode that were identified in the exper- iments both in the plenum and in the combustion chamber. The frequency and amplitude of velocity fluctuations predicted at limit cycle are used to reconstruct time resolved pressure fluctuations in the plenum and chamber and heat release rate fluctuations at two locations. For the pressure fluctuations, the analysis provides a suitable estimate of the limit cycle oscillation and suitably retrieves experimental data recorded in the MICCA setup and in particular reflects the difference in amplitude levels observed in these two cavities. Differences in measured and predicted amplitudes appear for the heat release rate fluctuations. Their amplitude is found to be directly linked to the rapid change in the FDF gain as the velocity fluctuation level reaches large amplitudes corresponding to the limit cycle, underlying the need of FDF information at high modulation amplitudes

Nautilia abyssi sp. nov., a thermophilic, chemolithoautotrophic, sulfur-reducing bacterium isolated from an East Pacific Rise hydrothermal vent

This is an author manuscript that has been accepted for publication in International Journal of Systematic and Evolutionary Microbiology, copyright Society for General Microbiology, but has not been copy-edited, formatted or proofed. Cite this article as appearing in International Journal of Systematic and Evolutionary Microbiology. This version of the manuscript may not be duplicated or reproduced, other than for personal use or within the rule of 'Fair Use of Copyrighted Materials' (section 17, Title 17, US Code), without permission from the copyright owner, Society for General Microbiology. The Society for General Microbiology disclaims any responsibility or liability for errors or omissions in this version of the manuscript or in any version derived from it by any other parties. The final copy-edited, published article, which is the version of record, can be found at http://mic.sgmjournals.org, and is freely available without a subscription.International audienceA novel strictly anaerobic, thermophilic, sulfur-reducing bacterium, designated PH1209(T), was isolated from an East Pacific Rise hydrothermal vent (1 degrees N) sample and studied using a polyphasic taxonomic approach. Cells were Gram-negative, motile rods (approx. 1.60 x 0.40 microm) with a single polar flagellum. Strain PH1209(T) grew at temperatures between 33 and 65 degrees C (optimum 60 degrees C), from pH 5.0 to 8.0 (optimum 6.0-6.5), and between 2 and 4 % (w/v) NaCl (optimum 3 %). Cells grew chemolithoautotrophically with H(2) as an energy source, S(0) as an electron acceptor and CO(2) as a carbon source. Strain PH1209(T) was also able to use peptone and yeast extract as carbon sources. The G+C content of the genomic DNA was 35 mol%. Phylogenetic analyses based on 16S rRNA gene sequencing showed that strain PH1209(T) fell within the order Nautiliales, in the class Epsilonproteobacteria. Comparative 16S rRNA gene sequence analysis indicated that strain PH1209(T) belonged to the genus Nautilia and shared 97.2 and 98.7 % 16S rRNA gene sequence identity, respectively, with the type strains of Nautilia lithotrophica and Nautilia profundicola. It is proposed, from the polyphasic evidence, that the strain represents a novel species, Nautilia abyssi sp. nov.; the type strain is PH1209(T) (=DSM 21157(T)=JCM 15390(T))

Extending the sub-sea-floor biosphere

En libre-accès sur Archimer : http://archimer.ifremer.fr/doc/2008/publication-4209.pdfInternational audienceSub-sea-floor sediments may contain two-thirds of Earth's total prokaryotic biomass. However, this has its basis in data extrapolation from ~500-meter to 4-kilometer depths, whereas the deepest documented prokaryotes are from only 842 meters. Here, we provide evidence for low concentrations of living prokaryotic cells in the deepest (1626 meters below the sea floor), oldest (111 million years old), and potentially hottest (~100 degrees C) marine sediments investigated. These Newfoundland margin sediments also have DNA sequences related to thermophilic and/or hyperthermophilic Archaea. These form two unique clusters within Pyrococcus and Thermococcus genera, suggesting unknown, uncultured groups are present in deep, hot, marine sediments (~54 degrees to 100 degrees C). Sequences of anaerobic methane-oxidizing Archaea were also present, suggesting a deep biosphere partly supported by methane. These findings demonstrate that the sub-sea-floor biosphere extends to at least 1600 meters below the sea floor and probably deeper, given an upper temperature limit for prokaryotic life of at least 113 degrees C and increasing thermogenic energy supply with depth

A spectroscopic hike in the U–O phase diagram

The U-O phase diagram is of paramount interest for nuclear-related applications and has therefore been extensively studied. Experimental data have been gathered to feed the thermodynamic calculations and achieve an optimization of the U-O system modelling. Although considered as well established, a critical assessment of this large body of experimental data is necessary, especially in light of the recent development of new techniques applicable to actinide materials. Here we show how in situ X-ray absorption near-edge structure (XANES) is suitable and relevant for phase diagram determination. New experimental data points have been collected using this method and discussed in regard to the available data. Comparing our experimental data with thermodynamic calculations, we observe that the current version of the U-O phase diagram misses some experimental data in specific domains. This lack of experimental data generates inaccuracy in the model, which can be overcome using in situ XANES. Indeed, as shown in the paper, this method is suitable for collecting experimental data in non-ambient conditions and for multiphasic systems

Flame and spray dynamics during the light-round process in an annular system equipped with multiple swirl spray injectors

A successful ignition in an annular multi-injector combustor follows a sequence of steps. The first injector is ignited; two arch-shaped flame branches nearly perpendicular to the combustor backplane form; they propagate, igniting each injection unit; they merge. In this paper, characterization of the propagation phase is performed in an annular combus- tor with spray flames fed with liquid n-hepane. The velocity and the direction of the arch- like flame branch are investigated. Near the backplane, the flame is moving in a purely azi- muthal direction. Higher up in the chamber, it is also moving in the axial direction due to the volumetric expansion of the burnt gases. Time-resolved particle image velocimetry (PIV) measurements are used to investigate the evaporating fuel droplets dynamics. A new result is that, during the light-round, the incoming flame front pushes the fuel droplets in the azimuthal direction well before its leading point. This leads to a decrease in the local droplet concentration and local mixture composition over not yet lit injectors. For the first time, the behavior of an individual injector ignited by the passing flame front is examined. The swirling flame structure formed by each injection unit evolves in time. From the igni- tion of an individual injector to the stabilization of its flame in its final shape, approxi- mately 50ms elapse. After the passage of the traveling flame, the newly ignited flame flashbacks into the injector during a few milliseconds, for example, 5 ms for the conditions that are tested. This could be detrimental to the service life of the unit. Then, the flame exits from the injection unit, and its external branch detaches under the action of cooled burnt gases in the outer recirculation zone (ORZ

From Historical Documents To Social Network Visualization: Potential Pitfalls and Network Modeling

International audienceWe describe the workflow followed by historians when conducting a Historical Social Network Analysis (HSNA) with five steps: textual sources acquisition, digitization, annotation, network creation, and analysis/visualization. While most analysis and visualization tools only support the last step, we argue that addressing the 2-3 last steps would boost the humanists' analytical capabilities. We explain why the network modeling process is particularly challenging and can lead to distortions of the sources, biases, and traceability problems. We list three main properties that we believe the constructed network should satisfy: alignment with reality/documents (not only with concepts), traceability (from documents to analysis/visualization and back), and simplicity (understandable by most and not more complex than needed). We claim that the model of bipartite dynamic multivariate network with roles allows an effective annotation/encoding of historical sources while satisfying these properties. We provide real-world examples of how this model has been used to answer socio-historical questions using visual analytics tools

Biodiversity and ecosystem services science for a sustainable planet: the DIVERSITAS vision for 2012–20

DIVERSITAS, the international programme on biodiversity science, is releasing a strategic vision presenting scientific challenges for the next decade of research on biodiversity and ecosystem services: “Biodiversity and Ecosystem Services Science for a Sustainable Planet”. This new vision is a response of the biodiversity and ecosystem services scientific community to the accelerating loss of the components of biodiversity, as well as to changes in the biodiversity science-policy landscape (establishment of a Biodiversity Observing Network — GEO BON, of an Intergovernmental science-policy Platform on Biodiversity and Ecosystem Services — IPBES, of the new Future Earth initiative; and release of the Strategic Plan for Biodiversity 2011–2020). This article presents the vision and its core scientific challenges.Fil: Larigauderie, Anne. DIVERSITAS. Muséum National d’Histoire Naturelle; FranciaFil: Prieur Richard, Anne Helene. DIVERSITAS. Muséum National d’Histoire Naturelle; FranciaFil: Mace, Georgina. Imperial College London. Center for Population Biology; Reino UnidoFil: Londsdale, Mark. CSIRO Ecosystem Sciences; AustraliaFil: Mooney, Harold A.. Stanford University. Department of Biological Sciences; Estados UnidosFil: Brussaard, Lijbert. Wageningen University, Soil Quality Department; Países BajosFil: Cooper, David. Secretariat of the Convention on Biological Diversity; CanadáFil: Wolfgang, Cramer. Institut Méditerranéen de Biodiversité et d’Ecologie marine et continentale; FranciaFil: Daszak, Peter. EcoHealth Alliance. Wildlife Trust; Estados UnidosFil: Diaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Duraiappah, Anantha. International Human Dimensions Programme; AlemaniaFil: Elmqvist, Thomas. University of Stockholm. Department of Systems Ecology and Stockholm Resilience Center; SueciaFil: Faith, Daniel. The Australian Museum; AustraliaFil: Jackson, Louise. University of California; Estados UnidosFil: Krug, Cornelia. DIVERSITAS. Muséum National d’Histoire Naturelle; FranciaFil: Leadley, Paul. Université Paris. Laboratoire Ecologie Systématique Evolution, Ecologie des Populations et Communautés; FranciaFil: Le Prestre, Philippe. Laval University; CanadáFil: Matsuda, Hiroyuki. Yokohama National University; JapónFil: Palmer, Margaret. University of Maryland; Estados UnidosFil: Perrings, Charles. Arizona State University; Estados UnidosFil: Pulleman, Mirjam. Wageningen University; Países BajosFil: Reyers, Belinda. Natural Resources and Environment; SudáfricaFil: Rosa, Eugene A.. Washington State University; Estados UnidosFil: Scholes, Robert J.. Natural Resources and Environment; SudáfricaFil: Spehn, Eva. Universidad de Basilea; SuizaFil: Turner II, B. L.. Arizona State University; Estados UnidosFil: Yahara, Tetsukazu. Kyushu University; Japó