803 research outputs found

    Valuing lagoons using a meta-analytical approach: Methodological and practical issues

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    Among coastal areas, lagoons are probably one of the most active and sensitive areas. They provide numerous goods and services that are of value to people. As public goods, there are freely accessible but in counterpart there are more endangered than other areas. Conflict uses between activities inside and outside the lagoons or between occasional and regular users imply to implement the lagoons economic values in order to provide a useful management tool. Many studies have been driven in order to estimate the impacts of the different activities on water quality and the willingness to pay for a better environment. We collect 32 lagoon studies providing 67 value observations in order to present a comprehensive meta-analysis of the valuation literature. This method allows estimating a function that takes into account the sites characteristics, methodological variables and lagoons services. The estimation of a meta-analytic function proves that all theses kinds of variables are important for the calculus of values. Moreover, we precisely determine the influence of the different variables on the value. Performing the transfer, we find an average transfer error amount equal to 87% but a median transfer error equal to 24%. This result due to a very small number of aberrant values is interesting with one-fourth of the transfers showing errors lower to 10% and nearly three-fourth of the transfers present errors lower to 50%.

    Three-dimensional magnetic field reconstruction in the VKS experiment through Galerkin transforms

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    International audienceWe present a method for three-dimensional (3D) magnetic field reconstruction based on Galerkin transforms. We test it over synthetic fields and real solenoidal (velocity) fields, measured in a water experiment. Our study shows that reliable reconstructions are possible provided that the probes are sufficiently sampled and located in shifted configurations. A preliminary application of our method is performed on results obtained in the VKS dynamo experiment (Bourgoin et al 2002 Phys. Fluids 14 3046). We show that the stationary dynamos obtained with counter-rotating impellers are mainly axisymmetric, with a non-axisymmetric part that decreases with increasing Reynolds numbers. Most of the azimuthal energy is localized near the (iron) impellers, confirming their importance in the dynamo process

    Protein Sequencing with an Adaptive Genetic Algorithm from Tandem Mass Spectrometry

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    In Proteomics, only the de novo peptide sequencing approach allows a partial amino acid sequence of a peptide to be found from a MS/MS spectrum. In this article a preliminary work is presented to discover a complete protein sequence from spectral data (MS and MS/MS spectra). For the moment, our approach only uses MS spectra. A Genetic Algorithm (GA) has been designed with a new evaluation function which works directly with a complete MS spectrum as input and not with a mass list like the other methods using this kind of data. Thus the mono isotopic peak extraction step which needs a human intervention is deleted. The goal of this approach is to discover the sequence of unknown proteins and to allow a better understanding of the differences between experimental proteins and proteins from databases

    Environmental Good Production in the Optimum Activities Portfolio of a Risk Averse Farmer

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    An analytical framework is proposed for analysis of environmental good production by farmers in the case of price uncertainty. Environmental good production contracted by means of agri-environmental agreements is treated as a risk less option in the farmer's production activities portfolio. Efficient frontiers were generated using mathematical programming farm level models of suckler cow farms in Monts du Cantal, in France. It was demonstrated that for a DARA risk averse farmer: 1) the agreement payment level is not without impact on the farming intensity on parcels not subscribed under the corresponding argi-environmental programme, 2) a lump sum payment matters under uncertainty, 3) the overall impact of the lump sum payment on environmental good production depends on the type of jointness in production of agricultural and environmental goods, and on the level of uncertainty.uncertainty, portfolio optimisation, biodiversity, agricultural policy, mathematical programming, Agricultural and Food Policy, Resource /Energy Economics and Policy, Q12, Q18, Q28,

    Variabilité de la morphologie chez Fusarium oxysporum f. sp. lycopersici

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    La variabilité morphologique chez #Fusarium oxysporum f. sp. #lycopersici a été recherchée à deux niveaux : au sein d'une population de conidies provenant du thalle d'un isolat (variabilité interclonale) et au sein d'une population de conidies provenant d'un thalle issu d'un clonage monospore (variabilité interclonale). Enfin, cette variabilité a été étudiée sur des cultures jeunes et âgées. L'ensemble des essais a été réalisé sur deux isolats. Les résultats mettent en évidence l'existence d'une variabilité morphologique importante, mais également des réponses différentes suivant les deux isolats. La variabilité interclonale n'a été observée que chez l'un des isolats et semble être une propriété constitutive de l'isolat. La variabilité interclonale se manifeste chez les deux isolats, mais uniquement au sein d'une population de conidies récoltées sur des thalles âgés. Dans ce dernier cas, on observe une forte augmentation de la fréquence d'apparition d'un morphotype considéré comme sénescent sans, toutefois, que cette forme soit irréversiblement acquise : on note un taux non négligeable de réversion vers des morphotypes considérés comme juvéniles. (Résumé d'auteur

    High energy blazars spectroscopy with X-Shooter on the VLT

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    We present results of observations in the UV to near-IR range for eight blazars, three of which have been recently discovered at Very High Energies (VHE) and five appearing as interesting candidates for VHE {\gamma}-ray detection. We focus in this paper on the search for their redshifts, which are unknown or considered as uncertain.Comment: 4 pages, 8 figures, to appear in the proceedings of the 5th International Symposium on High-Energy Gamma-Ray Astronomy (Gamma2012), July 9-13, 2012, Heidelberg, German

    Environmental good production in the optimum activities portfolio of a risk averse-farmer

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    An analytical framework is proposed for analysis of environmental good production by farmers in the case of price uncertainty. Environmental good production contracted by means of agri-environmental agreements is treated as a riskless option in the farmer’s production activities portfolio. It is shown that agri-environmental agreements aiming at biodiversity competing with beef production are likely to increase management intensity on the non-enrolled land, and that the effect of the payments for these agreements on the number of hectares enrolled is ambiguous. It is also demonstrated that an increase in the output price variability and/or a decrease in the level of decoupled subsidies will induce an increase (decrease) in the area enrolled in agreements aiming at biodiversity competing with (complementary to) beef production. The obtained results are illustrated by means of efficient frontiers generated using mathematical programming farm level models of suckler cow farms in Monts du Cantal, in France.uncertainty, portfolio optimisation, biodiversity, agricultural policy, mathematical programming

    Variabilité du pouvoir pathogène chez Fusarium oxysporum f. sp. lycopersici

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    Des essais ont été réalisés dans le but de vérifier la stabilité du pouvoir pathogène dans des descendances inter- et intraclonales de deux isolats de #Fusarium oxysporum f. sp. #lycopersici. Aucun changement de race n'a été enregistré ; en revanche, des variations d'agressivité ont été observées. chez l'un des isolats, cette variation se manifeste dans la descendance d'une culture jeune, tandis que chez le second, elle ne se révèle que dans la descendance de cultures âgées. Dans les deux cas, le niveau d'agressivité n'est pas lié à un morphotype particulier. Enfin, chez les deux isolats, le pouvoir pathogène est conservé au cours du vieillissement des cultures. (Résumé d'auteur

    Design of a Magnetic Vibration Absorber with Tunable Stiffnesses

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    International audienceThe design and characterisation of a magnetic vibration absorber (MVA), completely relying on magnetic forces, is addressed. A distinctive feature of the absorber is the ability of tuning the linear stiffness together with the nonlinear cubic and quintic stiffnesses by means of repulsive magnets located in the axis of the main vibrating magnetic mass, together with a set of corrective magnets located off the main axis. The tuning methodology is passive and relies only on three geometrical parameters. Consequently the MVA can be adjusted to design either a nonlinear tuned vibration absorber (NLTVA), a nonlinear energy sink (NES), or a bi-stable absorber with negative linear stiffness. The expressions of the stiffnesses are given from a multipole expansion of the magnetic fields of repulsive and corrective magnets. A complete static and dynamic characterisation is performed, showing the robustness of the modelling together with the ability of the MVA to work properly in different vibratory regimes, thus making it a suitable candidate for passive vibration mitigation in a wide variety of contexts
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