Mass transfer in a membrane aerated biofilm

We present experimental results of mass transfer of a non reactive tracer gas (neon)measured in aerobic heterotrophic biofilm developed from activated sludge. Biofilms are grown in various hydrodynamic conditions and the effective diffusivity is used to quantify the mass transfer through the biofilm. Beyond some cross-flow conditions, the effective diffusivity through the biofilm seems larger than in the bulk. This can be explained by a dispersion generated by convection inside the biofilm, as supported by an analytical flow model and in accordance to the numerical simulation proposed by Aspa et al. (2011)

Strategies for online inference of model-based clustering in large and growing networks

In this paper we adapt online estimation strategies to perform model-based clustering on large networks. Our work focuses on two algorithms, the first based on the SAEM algorithm, and the second on variational methods. These two strategies are compared with existing approaches on simulated and real data. We use the method to decipher the connexion structure of the political websphere during the US political campaign in 2008. We show that our online EM-based algorithms offer a good trade-off between precision and speed, when estimating parameters for mixture distributions in the context of random graphs.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS359 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Analyse de contaminants d’intérêt émergent dans l’Estuaire et le Golfe du Saint-Laurent par chromatographie liquide couplée à la spectrométrie de masse haute résolution

Les contaminants d’intérêt émergent (CIEs) ont fait l’objet d’un nombre croissant d’études ces dernières années, notamment dans les milieux aquatiques. Il existe cependant certains manques de connaissances concernant leur occurrence et leur distribution dans les systèmes hydrologiques complexes, notamment la distribution verticale à travers différentes masses d’eau. Les variations saisonnières entre conditions estivales et hivernales restent difficiles à établir en raison des conditions météorologiques hivernales rigoureuses au Canada, limitant l’accessibilité des échantillons. Ainsi, ce projet de maîtrise a porté sur l’étude de 90 CIEs, comprenant des pesticides, des produits pharmaceutiques et marqueurs anthropiques, des hormones et des substances perfluorées dans un environnement océanographique, soit l’Estuaire et le Golfe du Saint-Laurent (EGSL). Deux expéditions ont été menées en conditions hivernales (hivers 2019 et 2020) et une en conditions estivales (été 2019). Ces missions ont permis d’évaluer, dans un premier temps, la distribution spatiale des CIEs dans l’eau de surface le long de l’EGSL, puis, dans un second temps, la variation des concentrations de surface associées aux différentes températures, salinités, couvertures de glace, processus de dégradation ou débit du fleuve des saisons. Par ailleurs, un échantillonnage à plusieurs profondeurs durant l’hiver 2020 a permis de dresser un profil vertical des concentrations le long de l’Estuaire et du Golfe du Saint-Laurent. Finalement, la filtration de larges volumes d’eau de surface durant l’hiver 2020 a permis d’évaluer la concentration des CIEs adsorbés sur la matière en suspension (phase particulaire) et conséquemment, le partitionnement entre la phase dissoute et particulaire, influencé par la variation de la salinité et de la quantité de matière en suspension. Les analyses ont été effectuées grâce au développement et à la validation d’une nouvelle méthode multi-résidus impliquant la chromatographie liquide à ultra-haute performance (UHPLC) couplée à la spectrométrie de masse à haute résolution (HRMS). À notre connaissance, il s’agit de la première étude à caractériser divers contaminants émergents dans les eaux de l’Estuaire et du Golfe du Saint-Laurent, particulièrement pendant la période hivernale et à travers la colonne d’eau.Contaminants of Emerging Concern (CECs) have been increasingly studied since recent years, for instance in aquatic ecosystems. However, there exist significant knowledge gaps regarding their occurrence and distribution in complex hydrological systems, including their vertical distribution in different water bodies. Seasonal variations between summer and winter conditions are also difficult to establish because of the rigorous winter weather conditions in Canada, restricting the accessibility of samples. Thus, this project focused on the study of 90 CECs, including pesticides, pharmaceuticals and anthropogenic markers, hormones, and perfluorinated substances in an oceanographic environment, namely the St. Lawrence Estuary and Gulf (SLEG). Two expeditions were conducted under winter conditions (winters 2019 and 2020) and one under summer conditions (summer 2019). These expeditions first assessed the spatial distribution of CECs along the SLEG and, secondly, the seasonal and annual variations of the concentrations associated with the different temperatures, salinities, ice cover, degradation processes or seasonal river flow. In addition, sampling at multiple depths during the winter of 2020 allowed for documenting the vertical profiles of CECs throughout the SLEG. Finally, the filtration of large volumes of surface water during the winter of 2020 allowed for the evaluation of the CECs adsorbed onto suspended particle matter (SPM) and consequently, the partitioning between dissolved and particulate phases, influenced by salinity and SPM variations. Analyses were performed following the development and validation of a new multi-residue method involving ultra-high performance liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry (HRMS). To the best of our knowledge, this is the first study to report the occurrence of emerging contaminants in the SLEG, especially during the winter season and across the water column

The C(3P) + NH3 reaction in interstellar chemistry: II. Low temperature rate constants and modeling of NH, NH2 and NH3 abundances in dense interstellar clouds

A continuous supersonic flow reactor has been used to measure rate constants for the C + NH3 reaction over the temperature range 50 to 296 K. C atoms were created by the pulsed laser photolysis of CBr4. The kinetics of the title reaction were followed directly by vacuum ultra-violet laser induced fluorescence (VUV LIF) of C loss and through H formation. The experiments show unambiguously that the reaction is rapid at 296 K, becoming faster at lower temperatures, reaching a value of 1.8 10-10 cm3 molecule-1 s-1 at 50 K. As this reaction is not currently included in astrochemical networks, its influence on interstellar nitrogen hydride abundances is tested through a dense cloud model including gas-grain interactions. In particular, the effect of the ortho-to-para ratio of H2 which plays a crucial role in interstellar NH3 synthesis is examined

Multi-CPU and multi-GPU hybrid computations of multi-scale scalar transport

International audienceThe aim of this work is to propose an hybrid implementation of a semi-Lagrangian particle method on a multi-CPU and multi-GPU architecture. The applications we have in view deal with the transport of a passive scalar in a turbulent flow. For high Schmidt numbers (ratio of flow viscosity to scalar diffusivity), these problems exhibit two different scales: one related to the flow and the other -a smaller scale - to the scalar fluctuations. This scale separation motivates the use of hybrid methods where scalar and flow dynamics can be solved with different algorithms and at different resolutions. The coupling between these scales is done through the velocity field

Map design for visually impaired people: past, present, and future research

International audienceOrientation and mobility are amongst the most important challenges for visually impaired people. Tactile maps can provide them with spatial knowledge of their environment, thereby reducing fear related to travelling in space. To date, raised-line paper maps have been used to make geographic information accessible, but these paper maps have significant limitations with regards to content and the presentation of information. Recent advances in technology may help to design usable interactive maps that overcome such limitations. In this paper, we first review different accessible map concepts. We then present our design of an interactive map prototype, and provide evidence of this interactive map’s high user satisfaction and efficiency as compared to a regular raised-line paper map. To conclude, we suggest that advances in interactive technologies (e.g., haptic touch surfaces) provide a unique opportunity to design usable maps in the near future

Distribution maps of twenty-four Mediterranean and European ecologically and economically important forest tree species compiled from historical data collections

Species distribution maps are often lacking for scientific investigation and strategic management planning at international level. Here, we present the range-wide, natural distribution maps of twenty-four Mediterranean and European forest-tree species of key ecological and economic importance in the Mediterranean basin. Data on the geographic distribution of the twenty-four tree species were compiled from over one hundred published sources, making this contribution one of the most extensive resource available from historical data. Dataset can be accessed at: https://doi.org/10.5281/zenodo.822953. Associated metadata can be accessed at: http://www.fao.org/geonetwork/srv/en/metadata.show?id=56996. These data provide key spatial information to further investigate species occurrence-environment relationships, provide a baseline to assess the future impact of climate change, identify marginal populations with specific genetic resources, among other possible applications

Rapic project: toward a new generation of inexpensive heat exchanger-reactors for process intensification

Process intensification (PI) in chemical production is a major concern of chemical manufacturers. This alternative technology involves transposing syntheses into continuous plug flow reactors with process intensification, leading to a multifunctional heat exchanger-reactor. In this context, the RAPIC R&D project aims to develop an innovative low-cost component (in the 10 kg/hour range). This project deals with the design from the local to the global scale and with testing, from elementary mock-ups to pilot scale. The present paper gives a detailed description of this research project and presents the main results on specification and definition of the reaction channel and the first simple mock-ups

Kin'touch: understanding how visually impaired people explore tactile maps

International audienceTactile or interactive maps are largely used as an orientation aid for visually impaired people. Yet, little is known about haptic exploration strategies and their influence on the resultant cognitive mapping. We have designed a prototype with the potential to automatically analyze different users' exploration strategies. This prototype integrates data from the MS Kinect camera and a multi-touch table. It registers location of hands and digits on a tactile map. Results of preliminary studies show that this approach is promising

Individualized Visits to Foster the Engagement and the re-visit in Museums

International audienceMuseums have become places that, besides conserving and storing artefacts, provide visitors with education and amusement. They now have to compete with the entertainment industry to attract visitors and expand their audience. The use of digital technology is emerging as a solution.While many studies focus on the visitor side, we are interested in tools for museum staff. To understand their needs and processes, we adopted a participatory and iterative design process, involving museum professionals as end-users at each step (i.e. user observation, design, prototyping, users tests). We conducted 7 meetings, 4 interviews studies and 2 experimental observations with 12 museum experts (communication, IT, public and content experts) from 5 institutions (Exhibition Centres, Science Centre, Archaeological Museum, Museum of Fine Arts).Our analysis revealed two issues faced by these museums. First, despite the recommendation of institutional documents, visitors service is almost never involved before the end of the exhibition design process. Thus, they have no mean to shape the scenography in order to adapt it to visitors. Second, we identified a strong need for encouraging local visitors’ engagement and revisit. Diversifying the visits is a solution considered by museums, but relying on temporary exhibits is too costly for small museums and creating thematic visits is not participatory enough.The creation of individualized visits, allowing visitors to explore existing exhibition on their own depending on their needs and desires, meets both challenges. We thus focus on the design of tools that empower museum professionals to create such visits. We identified that museums need, first, to collect more information about their visitors and, second, to be able to create, evolve and maintain the solutions on their own according to visitors needs. Our aim is to design a tool which respects these two key points and could enable the creation of personalized and dynamic museum visits