279 research outputs found

    Volcanic CO2 Abundance of Kilauea Plume Retrieved by Meand of AVIRIS Data

    Get PDF
    Absorbing the electromagnetic radiation in several regions of the solar spectrum, CO2 plays an important role in the Earth radiation budget since it produces the greenhouse effect. Many natural processes in the Earth s system add and remove carbon dioxide. Overall, measurements of atmospheric carbon dioxide at different sites around the world show an increased carbon dioxide concentration in the atmosphere. At Mauna Loa Observatory (Hawaii) the measured carbon dioxide increased from 315 to 365 ppm, in the period 1958 2000 [Keeling et al., 2001]. While at the large scale, the relationship between CO2 increase and global warming is established [IPCC, 1996], at the local scale, many studies are still needed to understand regional and local sources of carbon dioxide, such as volcanoes. The volcanic areas are particularly rich in carbon dioxide; this is due to magma degassing in the summit craters region of active volcanoes, and to the presence of fractures and active faults [Giammanco et al., 1998]. Several studies estimate a global flux of volcanic CO2 (34+/-24)10(exp 6) tons/day from effusive volcanic emissions, such as the tropospheric volcanic plume (Table 1) [McClelland et al., 1989]. Plumes are a turbulent mixture of gases, solid particles and liquid droplets, emitted continuously at high temperature from summit craters, fumarolic fields or during eruptive episodes. Inside the plume, water vapour represents 70 90% of the volcanic gases. The main gaseous components are CO2, SO2, HCl, H2, H2S, HF, CO, N2 and CH4. Other plume components are volcanic ash, aqueous and acid droplets and solid sulphur-derived particles [Sparks et al., 1997]. Volcanic gases and aerosols are evidences of volcanic activity [Spinetti et al., 2003] and they have important climatic and environmental effects [Fiocco et al., 1994]. For example, Etna volcano is one of the world s major volcanic gas sources [Allard et al., 1991]. New studies on volcanic gaseous emissions have pointed out that a variation of the gas ratio CO2/SO2 is related to eruptive episodes [Caltabiano et al., 1994]. However, measurements and monitoring of volcanic carbon dioxide are difficult and often hazardous, due to the high background presence of atmospheric CO2 and the inaccessibility of volcanic sites. Hyperspectral remote sensing is a suitable technique to overcome the difficulties of ground measurement. It permits a rapid, comprehensive view of volcanic plumes and their evolution over time, detection of all gases with absorption molecular lines within the sensor s multispectral range and, in general, measurement of all the volatile components evolving from craters. The molecular and particle plume components scatter and absorb incident solar radiation. The integral of the radiation difference composes the signal measured by the remote spectrometer. The inversion technique consists of retrieving the plume component concentrations, hence decomposing the signal into the different contributions. The accuracy of remote sensing techniques depends primarily on the sensor capability and sensitivity

    L'innovation technologique face au changement climatique : quelle est la position de la France ?

    No full text
    Cet article propose une analyse statistique du positionnement et de la performance de la France en matière de technologies de lutte contre le réchauffement climatique. La méthodologie s'appuie sur une base de données décrivant l'ensemble des dépôts de brevets entre 1980 et 2008 dans 17 classes technologiques couvrant un large spectre de technologies liées au climat. Avec 5,2% des inventions brevetées en moyenne en 2008 dans les technologies étudiées, la France est en moyenne au 5ème rang mondial dans un classement dominé par les Etats-Unis, le Japon, la Corée du Sud et l'Allemagne. 20% des dépôts de brevet en France proviennent du secteur public, contre 10% dans les autres pays industrialisés. Plus de la moitié des inventions "climat" françaises sont protégés dans des pays étrangers, soit 1,5 fois plus que la moyenne mondiale. L'analyse par domaine technologique met en évidence un positionnement faible de la France dans les énergies renouvelables, dans lesquelles l'innovation est pourtant la plus dynamique au niveau mondial. En revanche, son positionnement est fort dans des secteurs comme le nucléaire (même si elle n'arrive qu'au troisième rang derrière le Japon et les Etats-Unis), la capture et séquestration du carbone (CSC), l'isolation, le ciment, le chauffage, l'hydraulique et les véhicules électriques et hybrides, où elle tire parti de la présence et du potentiel innovant des grandes firmes françaises d'envergure internationale (Air Liquide, Alstom, Areva, Electricité de France, Lafarge, PSA Peugeot Citroën, Renault, Saint-Gobain, Schlumberger) et des organismes publics de recherche scientifique (CNRS, Commissariat à l'Energie Atomique, Institut Français du Pétrole)

    In-flight radiometric calibration of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS)

    Get PDF
    A reflectance-based method was used to provide an analysis of the in-flight radiometric performance of AVIRIS. Field spectral reflectance measurements of the surface and extinction measurements of the atmosphere using solar radiation were used as input to atmospheric radiative transfer calculations. Five separate codes were used in the analysis. Four include multiple scattering, and the computed radiances from these for flight conditions were in good agreement. Code-generated radiances were compared with AVIRIS-predicted radiances based on two laboratory calibrations (pre- and post-season of flight) for a uniform highly reflecting natural dry lake target. For one spectrometer (C), the pre- and post-season calibration factors were found to give identical results, and to be in agreement with the atmospheric models that include multiple scattering. This positive result validates the field and laboratory calibration technique. Results for the other spectrometers (A, B and D) were widely at variance with the models no matter which calibration factors were used. Potential causes of these discrepancies are discussed

    GIVE: portable genome browsers for personal websites.

    Get PDF
    Growing popularity and diversity of genomic data demand portable and versatile genome browsers. Here, we present an open source programming library called GIVE that facilitates the creation of personalized genome browsers without requiring a system administrator. By inserting HTML tags, one can add to a personal webpage interactive visualization of multiple types of genomics data, including genome annotation, "linear" quantitative data, and genome interaction data. GIVE includes a graphical interface called HUG (HTML Universal Generator) that automatically generates HTML code for displaying user chosen data, which can be copy-pasted into user's personal website or saved and shared with collaborators. GIVE is available at: https://www.givengine.org/

    Accuracy Assessment of Global Internal-Tide Models Using Satellite Altimetry

    Get PDF
    Altimeter measurements are corrected for several geophysical parameters in order to access ocean signals of interest, like mesoscale or sub-mesoscale variability. The ocean tide is one of the most critical corrections due to the amplitude of the tidal elevations and to the aliasing phenomena of high-frequency signals into the lower-frequency band, but the internal-tide signatures at the ocean surface are not yet corrected globally. Internal tides can have a signature of several centimeters at the surface with wavelengths of about 50–250 km for the first mode and even smaller scales for higher-order modes. The goals of the upcoming Surface Water Ocean Topography (SWOT) mission and other high-resolution ocean measurements make the correction of these small-scale signals a challenge, as the correction of all tidal variability becomes mandatory to access accurate measurements of other oceanic signals. In this context, several scientific teams are working on the development of new internal-tide models, taking advantage of the very long altimeter time series now available, which represent an unprecedented and valuable global ocean database. The internal-tide models presented here focus on the coherent internal-tide signal and they are of three types: empirical models based upon analysis of existing altimeter missions, an assimilative model and a three-dimensional hydrodynamic model. A detailed comparison and validation of these internal-tide models is proposed using existing satellite altimeter databases. The analysis focuses on the four main tidal constituents: M2, K1, O1 and S2. The validation process is based on a statistical analysis of multi-mission altimetry including Jason-2 and Cryosphere Satellite-2 data. The results show a significant altimeter variance reduction when using internal-tide corrections in all ocean regions where internal tides are generating or propagating. A complementary spectral analysis also gives some estimation of the performance of each model as a function of wavelength and some insight into the residual non-stationary part of internal tides in the different regions of interest. This work led to the implementation of a new internal-tide correction (ZARON\u27one) in the next geophysical data records version-F (GDR-F) standards

    Modélisation de l'entretien du paysage par des herbivores en moyenne montagne : une approche multi-agents

    Get PDF
    L'abandon de l'utilisation des ressources herbagères par l'activité pastorale entraîne un appauvrissement de la diversité écologique et spécifique. A terme, cette évolution se traduit par le déplacement des activités humaines hors de ces zones et à un déséquilibre au niveau du territoire national. Un programme de recherche pluridisciplinaire, dans le cadre d'un Groupement d'intérêt Scientifique, a été mis en place dès 1994 pour élaborer de nouveaux modes de gestion qui concilient production agricole et entretien de l'espace en condition de sous chargement (peu d'animaux par unité de surface). Cet article s'inscrit dans une démarche d'acquisition de méthodes afin d'expérimenter des techniques de gestion de pâturage mixte bovins et chevaux selon une hypothèse de complémentarité entre ces deux espèces. La partie informatique présentée vise à simuler les dynamiques animales, végétales et paysagères futures et, à terme, proposer des protocoles de gestion aptes à répondre à ces nouvelles demandes. L'objectif de la modélisation que nous présentons est de simuler le fonctionnement de l'estive, afin de comprendre l'interaction entre l'évolution de la végétation, les déplacements et les actions des animaux en pâture. Un des modes de simulation utilise un système multi-agents. Le modèle conceptuel de la simulation est en cours de validation, il a été formalisé avec la notation graphique du langage de modélisation unifié (UML) et la version actuelle du logiciel est implémentée avec le langage de programmation Java. Pour suivre et enregistrer les localisations des animaux sur le terrain, ceux-ci sont équipés d'un récepteur satellite GPS (Global Positioning System). L'activité de pâturage des animaux est enregistrée par des colliers Ethosys. / The surrender of herbaceous resources by the grazing activity results in an impoverishment of both ecological and specific diversity. On the long term, this trend imposes the localization of human activities far from these zones and a national imbalance. A multidisciplinary research program was set up in 1994 with the aim of elaborating new ways of management, which would contribute to maintain both the productivity and the opened landscapes within the condition of low grazing pressure. This paper exposes the methods we elaborated in order to test several management techniques of grasslands by mean of cattle and horses within the hypothesis of complementarity between these two species. The computer science part of this paper presents the results of simulations of future dynamic behaviors of the animals, vegetation and landscape, in order to propound some management protocols. The simulator is based on a multi-agent system. The conceptual model, formalized with Unified Modeling Language graphical notation is actually in validation phase and the implementation of the software was done in the Java programming language. The following of the animals in the field was done by means of GPS equipments and the animal activity was recorded by Ethosys equipments

    Consequence of the tumor-associated conversion to cyclin D1b.

    Get PDF
    Clinical evidence suggests that cyclin D1b, a variant of cyclin D1, is associated with tumor progression and poor outcome. However, the underlying molecular basis was unknown. Here, novel models were created to generate a genetic switch from cyclin D1 to cyclin D1b. Extensive analyses uncovered overlapping but non-redundant functions of cyclin D1b compared to cyclin D1 on developmental phenotypes, and illustrated the importance of the transcriptional regulatory functions of cyclin D1b in vivo. Data obtained identify cyclin D1b as an oncogene, wherein cyclin D1b expression under the endogenous promoter induced cellular transformation and further cooperated with known oncogenes to promote tumor growth in vivo. Further molecular interrogation uncovered unexpected links between cyclin D1b and the DNA damage/PARP1 regulatory networks, which could be exploited to suppress cyclin D1b-driven tumors. Collectively, these data are the first to define the consequence of cyclin D1b expression on normal cellular function, present evidence for cyclin D1b as an oncogene, and provide pre-clinical evidence of effective methods to thwart growth of cells dependent upon this oncogenic variant
    corecore