Action versus Result-Oriented Schemes in a Grassland Agroecosystem: A Dynamic Modelling Approach

Effects of agri-environment schemes (AES) on biodiversity remain controversial. While most AES are action-oriented, result-oriented and habitat-oriented schemes have recently been proposed as a solution to improve AES efficiency. The objective of this study was to compare action-oriented, habitat-oriented and result-oriented schemes in terms of ecological and productive performance as well as in terms of management flexibility. We developed a dynamic modelling approach based on the viable control framework to carry out a long term assessment of the three schemes in a grassland agroecosystem. The model explicitly links grazed grassland dynamics to bird population dynamics. It is applied to lapwing conservation in wet grasslands in France. We ran the model to assess the three AES scenarios. The model revealed the grazing strategies respecting ecological and productive constraints specific to each scheme. Grazing strategies were assessed by both their ecological and productive performance. The viable control approach made it possible to obtain the whole set of viable grazing strategies and therefore to quantify the management flexibility of the grassland agroecosystem. Our results showed that habitat and result-oriented scenarios led to much higher ecological performance than the action-oriented one. Differences in both ecological and productive performance between the habitat and result-oriented scenarios were limited. Flexibility of the grassland agroecosystem in the result-oriented scenario was much higher than in that of habitat-oriented scenario. Our model confirms the higher flexibility as well as the better ecological and productive performance of result-oriented schemes. A larger use of result-oriented schemes in conservation may also allow farmers to adapt their management to local conditions and to climatic variations

Enhanced photocatalytic degradation of methylene blue: Preparation of TiO2/reduced graphene oxide nanocomposites by direct sol-gel and hydrothermal methods

In this study, two different preparation methods of titanium dioxide nanoparticles/reduced graphene oxide nanocomposites were investigated using direct sol-gel method followed by hydrothermal treatment or simple hydrothermal route. A different amount of graphene (1- 20%) was mixed with TiO2 for both series of samples in order to improve the photocatalytic activity. The influence of the preparation method on the physico-chemical properties was established by different characterization methods and the photocatalytic degradation of methylene blue (MB) under UV light irradiation was used as test reaction. The highest photocatalytic activity was observed for the nanocomposites containing 10 wt% of graphene. The elimination of MB can reach 93% and 82% for the nanocomposites with 10 wt% graphene prepared by the sol-gel and hydrothermal methods, respectively. These photocatalysts are promising for practical application in nanotechnology.Postprint (author's final draft

Novel antenna concepts via coordinate transformation

Coordinate transformation is an emerging field which offers a powerful and unprecedented ability to manipulate and control electromagnetic waves. Using this tool, we demonstrate the design of novel antenna concepts by tailoring their radiation properties. The wave manipulation is enabled through the use of engineered dispersive composite metamaterials that realize the space coordinate transformation. Three types of antennas are considered for design: a directive, a beam steerable and a quasi-isotropic one. Numerical simulations together with experimental measurements are performed in order to validate the coordinate transformation concept. Near-field cartography and far-field pattern measurements performed on a fabricated prototype agree qualitatively with Finite Element Method (FEM) simulations. It is shown that a particular radiation pattern can be tailored at ease into a desired one by modifying the electromagnetic properties of the space around radiator. This idea opens the way to novel antenna design techniques for various application domains such as the aeronautical and transport fields

Synthesis of tungsten carbide on Al-SBA-15 mesoporous materials by carburization.

[EN]Aluminum was incorporated into SBA-15 supports at molar ratios Si/Al ¼ 10 and 2 by the pH-adjusting method. The calcined mesoporous Al-SBA-15 supports, as well as the Al-free SBA-15 support, were impregnated with ammonium paratungstate ((NH4)10[H2W12O42]4H2O) aqueous solution. Tungsten carbide (W2C) was synthesized by temperature programmed carburization (TPC) from the WO3 sup- ported on Al-SBA-15 and SBA-15 in a flow of CH4/H2. These resultant materials were characterized by powder X-ray diffraction (XRD), N2 adsorption/desorption, 27Al NMR and Raman spectroscopies, and transmission electron microscopies (TEM and HRTEM). W2C species were obtained after the carburiza- tion process in all the materials. The mesoporous structure of the SBA-15 supports was preserved at all synthesis steps. XRD and TEM analyses revealed that the introduction of aluminum species into the SBA- 15 greatly enhanced the dispersion of WO3 and W2C phases during the calcination and carburization steps, respectively. In situ XRD measured during the carburization in a synchrotron facility provided further details of the reduction of tungsten trioxide species as a function of temperature. The presence of aluminum in the SBA-15 notably affected the distribution and the reduction temperature of the tungsten oxide species

Design of Multicationic Copper-Bearing Layered Double Hydroxides for Catalytic Application in Biorefinery

Ethanol has been used as a renewable hydrogen-donor in the conversion of a lignin model molecule in subcritical conditions. Noble metal-free porous mixed oxides, obtained by activation of Cu-Ni-Al and Cu-Ni-Fe layered double hydroxide (LDH) precursors, have been used as heterogeneous catalysts for Meerwein-Ponndorf-Verley (MPV) hydrogen transfer and further hydrogenation by ethanol dehydrogenation products. Both the Cu/(Cu+Ni) ratio and the nature of the trivalent cation (Al or Fe) affect the activity of the catalysts, as well as the selectivity towards the different steps of the hydrogenation reactions and the cleavage of lignin-like phenylether bonds. Accounting for the peculiar behaviour of Cu2+ and M(III) cations in the synthesis of LDHs, the coprecipitation of the precursors has been monitored by titration experiments. Structural and textural properties of the catalysts are closely related to the composition of the LDH precursors

Livestock and the functional habitat of vicuñas in Ecuador : a new puzzle

Includes supplementary Appendix S1.Whether interactions between wildlife and livestock are competitive or facilitative is context dependent. Intermediary factors that explain how context (seasonal or regional characteristics of the ecological community) affects these interactions are rarely reported. We compared activity time and density in vicuñas (Vicugna vicugna) introduced into the Chimborazo Faunal Production Reserve (CFPR), Ecuador, to describe how they interact with livestock. We compared vicuña density in wetlands and uplands (two landscape structures) with and without livestock (two conditions) using an isodar approach. We measured, over two seasons, vicuña forage abundance, composition, preference and accessibility, time vicuñas spent vigilant, and their flight distances on approach. We tested optimal foraging theory relating to the hypothesis that time mediates behavior, and found that vicuñas were no less frequently vigilant, nor were flight distances greater, during a wet season or in habitats of greater forage abundance and accessibility. We also found no evidence that vicuña behavior was density dependent; instead, we found that more time was spent vigilant by vicuñas when they foraged near livestock in rainy regions during the dry season. Although forage abundance was similar throughout CFPR during a dry season, better forage quality in areas occupied by livestock may constitute an effect of their facilitating vicuñas. A puzzling finding, because it was not explained by any of the other variables we measured, was that at low densities vicuñas selected habitat irrespective of livestock, and where their density was higher, it was doubly so adjacent to livestock. We conclude that in the CFPR, spatial heterogeneity in habitat quality determines the interactions between livestock and vicuñas. To support recommendations that minimize competition between wildlife and livestock, and to expand on descriptions of the contexts that determine the direction of species interactions, future study may require a wider sampling of the densities of sympatric large herbivores in general, and, in the CFPR, a closer resolution of spatial heterogeneity in forage plant quality

Chloroquine Clinical Failures in P. falciparum Malaria Are Associated with Mutant Pfmdr-1, Not Pfcrt in Madagascar

Molecular studies have demonstrated that mutations in the Plasmodium falciparum chloroquine resistance transporter gene (Pfcrt) play a major role in chloroquine resistance, while mutations in P. falciparum multidrug resistance gene (Pfmdr-1) act as modulator. In Madagascar, the high rate of chloroquine treatment failure (44%) appears disconnected from the overall level of in vitro CQ susceptibility (prevalence of CQ-resistant parasites <5%) or Pfcrt mutant isolates (<1%), strongly contrasting with sub-Saharan African countries. Previous studies showed a high frequency of Pfmdr-1 mutant parasites (>60% of isolates), but did not explore their association with P. falciparum chloroquine resistance. To document the association of Pfmdr-1 alleles with chloroquine resistance in Madagascar, 249 P. falciparum samples collected from patients enrolled in a chloroquine in vivo efficacy study were genotyped in Pfcrt/Pfmdr-1 genes as well as the estimation of the Pfmdr-1 copy number. Except 2 isolates, all samples displayed a wild-type Pfcrt allele without Pfmdr-1 amplification. Chloroquine treatment failures were significantly associated with Pfmdr-1 86Y mutant codon (OR = 4.6). The cumulative incidence of recurrence of patients carrying the Pfmdr-1 86Y mutation at day 0 (21 days) was shorter than patients carrying Pfmdr-1 86N wild type codon (28 days). In an independent set of 90 selected isolates, in vitro susceptibility to chloroquine was not associated with Pfmdr-1 polymorphisms. Analysis of two microsatellites flanking Pfmdr-1 allele showed that mutations occurred on multiple genetic backgrounds. In Madagascar, Pfmdr-1 polymorphism is associated with late chloroquine clinical failures and unrelated with in vitro susceptibility or Pfcrt genotype. These results highlight the limits of the current in vitro tests routinely used to monitor CQ drug resistance in this unique context. Gaining insight about the mechanisms that regulate polymorphism in Pfmdr1 remains important, particularly regarding the evolution and spread of Pfmdr-1 alleles in P. falciparum populations under changing drug pressure which may have important consequences in terms of antimalarial use management