Towards long-term standardised carbon and greenhouse gas observations for monitoring Europe's terrestrial ecosystems : a review

Research infrastructures play a key role in launching a new generation of integrated long-term, geographically distributed observation programmes designed to monitor climate change, better understand its impacts on global ecosystems, and evaluate possible mitigation and adaptation strategies. The pan-European Integrated Carbon Observation System combines carbon and greenhouse gas (GHG; CO2, CH4, N2O, H2O) observations within the atmosphere, terrestrial ecosystems and oceans. High-precision measurements are obtained using standardised methodologies, are centrally processed and openly available in a traceable and verifiable fashion in combination with detailed metadata. The Integrated Carbon Observation System ecosystem station network aims to sample climate and land-cover variability across Europe. In addition to GHG flux measurements, a large set of complementary data (including management practices, vegetation and soil characteristics) is collected to support the interpretation, spatial upscaling and modelling of observed ecosystem carbon and GHG dynamics. The applied sampling design was developed and formulated in protocols by the scientific community, representing a trade-off between an ideal dataset and practical feasibility. The use of open-access, high-quality and multi-level data products by different user communities is crucial for the Integrated Carbon Observation System in order to achieve its scientific potential and societal value.Peer reviewe

Exploring diversity in ensemble classification: Applications in large area land cover mapping

Ensemble classifiers, such as random forests, are now commonly applied in the field of remote sensing, and have been shown to perform better than single classifier systems, resulting in reduced generalisation error. Diversity across the members of ensemble classifiers is known to have a strong influence on classification performance - whereby classifier errors are uncorrelated and more uniformly distributed across ensemble members. The relationship between ensemble diversity and classification performance has not yet been fully explored in the fields of information science and machine learning and has never been examined in the field of remote sensing. This study is a novel exploration of ensemble diversity and its link to classification performance, applied to a multi-class canopy cover classification problem using random forests and multisource remote sensing and ancillary GIS data, across seven million hectares of diverse dry-sclerophyll dominated public forests in Victoria Australia. A particular emphasis is placed on analysing the relationship between ensemble diversity and ensemble margin - two key concepts in ensemble learning. The main novelty of our work is on boosting diversity by emphasizing the contribution of lower margin instances used in the learning process. Exploring the influence of tree pruning on diversity is also a new empirical analysis that contributes to a better understanding of ensemble performance. Results reveal insights into the trade-off between ensemble classification accuracy and diversity, and through the ensemble margin, demonstrate how inducing diversity by targeting lower margin training samples is a means of achieving better classifier performance for more difficult or rarer classes and reducing information redundancy in classification problems. Our findings inform strategies for collecting training data and designing and parameterising ensemble cla

A fraction to fraction study of photo-oxidation of BAL 150 crude oil asphaltenes

Sun light plays an important role in the degradation of oil spilled at sea or ground surface. Nevertheless, the efficience of photo-oxidation as a weathering process was hardly studied in asphaltenes, the most recalcitrant of petrogenic contaminants. Asphaltenes precipitated from Blend Arabian Light crude oil topped at 150 °C were exposed to UV and visible light sources for time durations up to 140 days, analyzed globally, then fractionated by sequential elution solvent chromatography. FTIR spectroscopy, elemental analysis, NMR, UV-fluorescence, GC and GC/MS analyses were implemented to investigate structural changes potentially induced by photo-oxidation. No obvious effect could be detected by overall approaches, whereas fraction to fraction analyses evidenced significant variations in the gravimetric distribution of asphaltene constituents, accompanied by changes in functionality linked to limited oxidation processes. Under our experimental conditions, most observed changes were suggestive of an increase in carbonyl, phenolic, sulfoxyde and carboxylic groups after light exposure, without significant alteration of the hydrocarbon skeletons of polyaromatic and alkyl compounds associated with the asphaltene matrix

Cartographie des habitats intertidaux du bassin d’Arcachon par imagerie optique et radar

National audienceObjectifs : - Exploitation en synergie de données radar et optiques ; - Discrimination, identification et cartographie exhaustive des substrats durs et meubles ainsi que des principales espèces végétales micro à macroscopiques ; - Quantification optique/radar de paramètres biologiques (composition, abondance spécifique, répartition surfacique) et sédimentaires (minéralogie, teneur en eau) ; - Validation d’une ou plusieurs stratégies de cartographie valorisables par des services GMES (Programme INFOLITTORAL-1, programme Territoire de Démonstration), implicitement adaptées aux exigences des missions de gestion des domaines naturels et exploités

Study of novel oxyfluoronitride bioglasses

International audienceBioglasses are used as bone substitutes and prosthetic coatings. Following implantation, they are predisposed to generate a series of physicochemical reactions at the glass-bone interface. Bioglasses with molar composition: 55SiO2–8.5CaO–31.5Na2O–5CaF2 have been synthesized and characterized. However, because of their poor strength, doping with nitrogen was performed on these glasses to increase their mechanical properties. The Young's elastic moduli, Vicker's microhardnesses, and the fracture toughnesses were measured and observed to increase linearly with nitrogen content in each of these systems. These results are consistent with the incorporation of nitrogen into the glass structure in three-fold coordination with silicon. Fluorine addition significantly decreases the thermal property values but the mechanical properties of these glasses remain unchanged with fluorine. The characterization of these N and F substituted bioglasses using 29Si MAS NMR have shown that the increase in rigidity of the glass network can be explained by the formation of SiO3N, SiO2N2 tetrahedra and Q4 units with extra bridging anions at the expense of Q3 units. The bioactivity of the glasses has been evaluated by soaking them in simulated body fluid (SBF) and showed that all oxyfluonitrides glasses are bioactives. Cytotoxicity tests based on different concentrations of bioglass powders in a cell growth environment have been also showed that they are not cytotoxi

Structural and theoretical studies of 4,4 '-[1,4-phenylene-bis(azanediyl)]dipent-3-en-2-one: evidence of a pi-delocalized keto-enamine

In this work we present the synthesis of 4,4'-[1,4-phenylene-bis(azanediyl)]dipent-3-en-2-one. Evidence is proposed for the presence of various tautomers of this molecule which are complemented with theoretical density functional theory (DFT)-B3LYP/6-31G* calculations to characterize the potential energy surface of these species. The experimentally observed 3b isomer crystallizes as an orthorhombic Pbcn structure; a = 10.8412(10) angstrom, b = 8.9205(7) angstrom, c = 14.9949(13) angstrom, V = 1450.1(2) angstrom(3), Z = 4 with a final R value is 0.038. From our X-Ray crystallographic analysis an intramolecular hydrogen N-H center dot center dot center dot O interaction is observed