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

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

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

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

Multi-scale problems, high performance computing and hybrid numerical methods

International audienceThe turbulent transport of a passive scalar is an important and challenging problem in many applications in fluid mechanics. It involves different range of scales in the fluid and in the scalar and requires important computational resources. In this work we show how hybrid numerical methods, combining Eulerian and Lagrangian schemes, are natural tools to address this multi-scale problem. One in particular shows that in homogeneous turbulence experiments at various Schmidt numbers these methods allow to recover the theoretical predictions of universal scaling at a minimal cost. We also outline hybrid methods can take advantage of heterogeneous platforms combining CPU and GPU processors

Near-field spectroscopy of low-loss waveguide integrated microcavities

International audienceA scanning near-field spectroscopy method is used to observe loss reduction and Q-factor enhancement due to transverse-mode profile matching within photonic-crystal microcavities. Near-field measurements performed directly on cavity modes are compared with three-dimensional calculations and quantitative agreement is observed. (c) 2006 American Institute of Physics

Трехкоординатный пьезокерамический сканер на биморфных пьезо-элементах для зондового наномикроскопа

Предложена и исследована конструкция пьезокерамического сканера для наномикроскопов на основе диморфных пьезоэлементов. Построена и исследована модель сканера при помощи программы MicroCap 7.0