Magnetic field effect on the dielectric constant of glasses: Evidence of disorder within tunneling barriers

The magnetic field dependence of the low frequency dielectric constant $e_r$(H) of a structural glass a - SiO2 + xCyHz was studied from 400 mK to 50 mK and for H up to 3T. Measurement of both the real and the imaginary parts of $e_r$ is used to eliminate the difficult question of keeping constant the temperature of the sample while increasing H: a non-zero $e_r$(H) dependence is reported in the same range as that one very recently reported on multicomponent glasses. In addition to the recently proposed explanation based on interactions, the reported $e_r$(H) is interpreted quantitatively as a consequence of the disorder lying within the nanometric barriers of the elementary tunneling systems of the glass.Comment: latex Bcorrige1.tex, 5 files, 4 figures, 7 pages [SPEC-S02/009

Analyse d’un corpus vidéo d’interactions entre pairs en classe de sciences en école d’immersion française aux Etats-unis

Communication orale dans le cadre du séminaire ELSE Education en Langues Secondes et Etrangères. LabEX ASLAN. 5 février 2014, ICAR, Lyon

Analyse d’un corpus vidéo d’interactions entre pairs en classe de sciences en école d’immersion française aux Etats-unis

Communication orale dans le cadre du séminaire ELSE Education en Langues Secondes et Etrangères. LabEX ASLAN. 5 février 2014, ICAR, Lyon

Two-phase Couette–Taylor flow: Arrangement of the dispersed phase and effects on the flow structures

This study investigates the mutual interactions between a continuous and a dispersed phase (noncondensable or condensable) in the well-known Couette–Taylor flow between two concentric cylinders at low Reynolds numbers, where the outer cylinder is immobilized. In this experiment, the turbulent structures take place progressively. The noncondensable dispersed phase (air) is introduced either by ventilation, generated by agitation of a free surface situated at the top of the gap between the two cylinders. The condensable dispersed phase is generated by cavitation due to a drop in pressure. Comparisons are made between the single phase flow patterns and those observed in ventilated or cavitating flow. Two particular arrangements of the dispersed phase are experimentally evident, according to the Reynolds number of the flow. For low Reynolds numbers, bubbles are trapped in the core of the Taylor cells, whereas they migrate to the outflow regions near the inner cylinder for higher Reynolds numbers. Assessment of the forces applied to the bubbles and computation of their equilibrium position can act as a base in describing the bubble capture. When bubbles are located near the wall in the outflow region, it is found that the three first instabilities are strongly influenced by the dispersed phase. The cavitating flow is also characterized by an earlier appearance of the third instability

Mustering the power of ecosystems for adaptation to climate change

Mountain social-ecological systems (SES) supply important ecosystem services that are threatened by climate change. In mountain SES there is a paradox between high community capacity to cope with extremes, and governance structures and processes that constrain that capacity from being realised. Climate adaptation that maintains livelihoods and supply of ecosystem services can catalyse this innate adaptive capacity if new adaptive governance arrangements can be created. Using the French Alps as a case study, we outline a participative framework for transformative adaptation that links adaptive capacity and governance to provide social innovation and ecosystem-based adaptation solutions for mountain SES. Grassland management was the main entry point for adaptation: bundles of adaptation services supplied by the landscape mosaic of biodiverse grassland types can maintain agricultural production and tourism and facilitate income diversification. Deliberate management for core adaptation services like resilient fodder production, erosion control, shade or aesthetic value generates co-benefits for future transformation ability. People activate bundles of adaptation services along adaptation pathways and realise benefits via co-production with other forms of capital including traditional knowledge or social networks. Common and distinctive adaptation services in each pathway create options for transformation if barriers from interactions between values and rules across scales can be overcome. For example conserving mown terraces which is a critical adaptation nexus reflects a complex interplay of values, markets and governance instruments from local to European scales. We conclude that increasing stakeholders capacity to mobilise adaptation services is critical for empowering them to implement adaptation to global change.This work was funded by French Agence Nationale pour la Recherche BiodivERsA REGARDS (ANR-12-EBID-004-01), MtnPaths (ANR-16-CE93-0008-01), Labex Item (ANR-10-LABX-50-01) and Investissements d’Avenir CDP Trajectories (ANR-15-IDEX-02)