Drought effect on isoprene production and consumption in Biosphere 2 tropical rainforest

Isoprene is the most abundant of the hydrocarbon compounds emitted from vegetation and plays a major role in tropospheric chemistry. Models predict that future climate change scenarios may lead to an increase in global isoprene emissions as a consequence of higher temperatures and extended drought periods. Tropical rainforests are responsible for more than 80% of global isoprene emissions, so it is important to obtain experimental data on isoprene production and consumption in these ecosystems under control of environmental variables. We explored isoprene emission and consumption in the tropical rainforest model ecosystem of Biosphere 2 laboratory during a mild water stress, and the relationship with light and temperature. Gross isoprene production (GIP) was not significantly affected by mild water stress in this experiment because the isoprene emitters were mainly distributed among the large, canopy layer trees with deep roots in the lower soil profile where water content decreased much less than the top 30 cm. However, as found in previous leaf level and whole canopy studies, the ecosystem gross primary production was reduced by (32%) during drought, and as a consequence the percentage of fixed C lost as isoprene tended to increase during drought, from ca. 1% in wet conditions to ca. 2% when soil water content reached its minimum. GIP correlated very well with both light and temperature. Notably, soil isoprene uptake decreased dramatically during the drought, leading to a large increase in daytime net isoprene fluxes

P2 mesh optimization operators

International audienceCurved mesh generation starting from a P1 mesh relies on mesh deformation and mesh optimization techniques. Mesh optimization techniques consist in locally modifying the mesh in order to improve it with respect to a given quality criterion. This work presents the generalization of two mesh quality-based optimization operators to P2 meshes. The generalized operators consist in mesh smoothing and generalized swapping. With the use of these operators, P2 mesh generation starting from a P1 mesh is more robust and P2 connectivity-change moving mesh methods for large displacements are now possible

Search of Dark Matter Annihilation in the Galactic Centre using the ANTARES Neutrino Telescope

A search for high-energy neutrinos coming from the direction of the GalacticCentre is performed using the data recorded by the ANTARES neutrino telescopefrom 2007 to 2012. The event selection criteria are chosen to maximise thesensitivity to possible signals produced by the self-annihilation of weaklyinteracting massive particles accumulated around the centre of the Milky Waywith respect to the atmospheric background. After data unblinding, the numberof neutrinos observed in the line of sight of the Galactic Centre is found tobe compatible with background expectations. The 90% C.L. upper limits in termsof the neutrino+anti-neutrino flux, $\rm \Phi_{\nu_{\mu}+\bar{\nu}_\mu}$, andthe velocity averaged annihilation cross-section, $\rm$, arederived for the WIMP self-annihilation channels into \rmb\bar{b},W^{+}W^{-},\tau^{+}\tau^{-},\mu^{+}\mu^{-},\nu\bar{\nu}. The ANTARESlimits for $\rm$ are shown to be the most stringent for aneutrino telescope over the WIMP masses $\rm 25\,GeV < M_{WIMP} < 10\,TeV$

KM3NeT broadcast optical data transport system

The optical data transport system of the KM3NeT neutrino telescope at the bottom of the Mediterranean Sea will provide more than 6000 optical modules in the detector arrays with a point-to-point optical connection to the control stations onshore. The ARCA and ORCA detectors of KM3NeT are being installed at a depth of about 3500 m and 2500 m, respectively and their distance to the control stations is about 100 kilometers and 40 kilometers. In particular, the two detectors are optimised for the detection of cosmic neutrinos with energies above about 1 TeV (ARCA) and for the detection of atmospheric neutrinos with energies in the range 1 GeV-1 TeV (ORCA). The expected maximum data rate is 200 Mbps per optical module. The implemented optical data transport system matches the layouts of the networks of electro-optical cables and junction boxes in the deep sea. For efficient use of the fibres in the system the technology of Dense Wavelength Division Multiplexing is applied. The performance of the optical system in terms of measured bit error rates, optical budget are presented. The next steps in the implementation of the system are also discussed