Olfactory and visual species recognition in newts and their role in hybridization

Mating patterns between hybridizing taxa are often conditional to the mechanisms underlying species recognition. During mate choice, individuals often assess information displayed by potential mates on several sensory channels. The reliance on more than one modality is particularly expected whenever transmission conditions are variable or signals subject to wear. Determining the sensory bases of species recognition is, thus, crucial to assess the effect of the signalling environment on the hybridization process between species where mate choice occurs. We addressed this issue in two newt species, Lissotriton helveticus and L. vulgaris, that hybridize and breed in aquatic habitats disturbed by various natural processes. We measured visual and olfactory preferences in males and females. Visual and olfactory recognition was detected in L. helveticus males and L. vulgaris females. In contrast, we observed limited olfactory recognition in L. helveticus females and no evidence of recognition at all in L. vulgaris males. In addition, one single variable, body size, strongly influenced female preference. Ecological factors modulating visual signalling conditions and the body size ratio in males are, thus, likely to influence the probability of heterospecific mating. This study highlights the need to consider more largely environmental factors affecting communication in the hybridization process

Indoor Optical Wireless Communication Coverage Optimization Using a SiPM Photoreceiver

International audienceAlthough optical wireless communication (OWC) is seen as a promising complementary technology to radio frequency systems, its deployment is currently hampered by its limited communication range and the lack of compactness of its transceivers. A partial solution lies in using more sensitive photoreceivers, such as arrays of single photon avalanche diodes (SPAD). Despite their limited bandwidth and non-linearity, such devices have been shown to support Gbps data transmission while providing greatly enhanced sensitivity compared to conventional photodiodes (PD). However, their potential to increase the communication coverage of an indoor OWC system has never been studied. In this paper, a simulation framework for evaluating this metric using a SPAD-based indoor OWC system is thus detailed and implemented. Results show that an array of SPADs in the order of a mm 2 is enough to ensure connectivity over a whole 16 m 2 room, whereas similar performance with a PD requires a sensitive area of several hundreds of mm 2 , hence demonstrating the interest of SPADs for coverage as well as compactness optimization in OWC. Index Terms-single photon avalanche diode (SPAD), optical wireless communications (OWC), LiF

Photon Bunching in Cathodoluminescence

International audienc

Quantum Hall effect in epitaxial graphene with permanent magnets

International audienceWe have observed the well-kown quantum Hall effect (QHE) in epitaxial graphene grown on silicon carbide (SiC) by using, for the first time, only commercial NdFeB permanent magnets at low temperature. The relatively large and homogeneous magnetic field generated by the magnets, together with the high quality of the epitaxial graphene films, enables the formation of well-developed quantum Hall states at Landau level filling factors v = ±2, commonly observed with superconducting electro-magnets. Furthermore, the chirality of the QHE edge channels can be changed by a top gate. These results demonstrate that basic QHE physics are experimentally accessible in graphene for a fraction of the price of conventional setups using superconducting magnets, which greatly increases the potential of the QHE in graphene for research and applications

The VATO project Development and validation of a dynamic transfer model of tritium in grassland ecosystem

International audienceIn this paper, a dynamic compartment model with a high temporal resolution has been investigated to describe tritium transfer in grassland ecosystems exposed to atmospheric 3H releases from nuclear facilities under normal operating or accidental conditions. TOCATTA-χ model belongs to the larger framework of the SYMBIOSE modelling and simulation platform that aims to assess the fate and transport of a wide range of radionuclides in various environmental systems. In this context, the conceptual and mathematical models of TOCATTA-χ have been designed to be relatively simple, minimizing the number of compartments and input parameters required. In the same time, the model achieves a good compromise between easy-to-use (as it is to be used in an operational mode), explicative power and predictive accuracy in various experimental conditions. In the framework of the VATO project, the model has been tested against two-year-long in situ measurements of 3H activity concentration monitored by IRSN in air, groundwater and grass, together with meteorological parameters, on a grass field plot located 2 km downwind of the AREVA NC La Hague nuclear reprocessing plant, as was done in the past for the evaluation of transfer of 14C in grass. By considering fast exchanges at the vegetation-air canopy interface, the model correctly reproduces the observed variability in TFWT activity concentration in grass, which evolves in accordance with spikes in atmospheric HTO activity concentration over the previous 24 h. The average OBT activity concentration in grass is also correctly reproduced. However, the model has to be improved in order to reproduce punctual high concentration of OBT activity, as observed in December 2013. The introduction of another compartment with a fast kinetic (like TFWT) - although outside the model scope - improves the predictions by increasing the correlation coefficient from 0.29 up to 0.56 when it includes this particular point. Further experimental investigation will be undertaken by IRSN and EDF next year to better evaluate (and properly model) other aspects of tritium transfer where knowledge gaps have been identified in both experimental and modelling areas. © 2016 Elsevier Lt

The VATO project An original methodology to study the transfer of tritium as HT and HTO in grassland ecosystem

International audienceTritium (3H) is mainly released into the environment by nuclear power plants, military nuclear facilities and nuclear reprocessing plants. The construction of new nuclear facilities in the world as well as the evolution of nuclear fuel management might lead to an increase of 3H discharges from the nuclear industry. The VATO project was set up by IRSN (Institut de Radioprotection et de Sûreté Nucléaire) and EDF (Electricité de France) to reduce the uncertainties in the knowledge about transfers of 3H from an atmospheric source (currently releasing HT and HTO) to a grassland ecosystem. A fully instrumented technical platform with specifically designed materials was set up downwind of the AREVA NC La Hague reprocessing plant (Northwest of the France). This study, started in 2013, was conducted in four main steps to provide an hourly data set of 3H concentrations in the environment, adequate to develop and/or validate transfer models. It consisted first in characterizing the physico-chemical forms of 3H present in the air around the plant. Then, 3H transfer kinetics to grass were quantified regarding contributions from various compartments of the environment. For this purpose, an original experimental procedure was provided to take account for biases due to rehydration of freeze-dried samples for the determination of OBT activity concentrations in biological samples. In a third step, the 3H concentrations measured in the air and in rainwater were reconstructed at hourly intervals. Finally, a data processing technique was used to determine the biological half-lives of OBT in grass. © 2016 Elsevier Lt