100 research outputs found

    Procédé de préparation d’une couche mince à caractère photovoltaïque à hétérojonction

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    Cross-linkable azido C60-fullerene derivatives for efficient thermal stabilization of polymer bulk-heterojunction solar cells

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    International audienceOriginal [60]PCBM-inspired fullerene derivatives bearing an azidofunctional group were synthesized. By incorporating an optimizedquantity of this thermal cross-linker additive in the P3HT:[60]PCBMphotoactive layer, an impressive stabilization of the bulk-heterojunctionmorphology at its optimal photovoltaic performance wasachieved

    Effects of Climate Change on Ticks and Tick-Borne Diseases in Europe

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    Zoonotic tick-borne diseases are an increasing health burden in Europe and there is speculation that this is partly due to climate change affecting vector biology and disease transmission. Data on the vector tick Ixodes ricinus suggest that an extension of its northern and altitude range has been accompanied by an increased prevalence of tick-borne encephalitis. Climate change may also be partly responsible for the change in distribution of Dermacentor reticulatus. Increased winter activity of I. ricinus is probably due to warmer winters and a retrospective study suggests that hotter summers will change the dynamics and pattern of seasonal activity, resulting in the bulk of the tick population becoming active in the latter part of the year. Climate suitability models predict that eight important tick species are likely to establish more northern permanent populations in a climate-warming scenario. However, the complex ecology and epidemiology of such tick-borne diseases as Lyme borreliosis and tick-borne encephalitis make it difficult to implicate climate change as the main cause of their increasing prevalence. Climate change models are required that take account of the dynamic biological processes involved in vector abundance and pathogen transmission in order to predict future tick-borne disease scenarios

    Tick burden on European roe deer (Capreolus capreolus)

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    In our study we assessed the tick burden on roe deer (Capreolus capreolus L.) in relation to age, physical condition, sex, deer density and season. The main objective was to find predictive parameters for tick burden. In September 2007, May, July, and September 2008, and in May and July 2009 we collected ticks on 142 culled roe deer from nine forest departments in Southern Hesse, Germany. To correlate tick burden and deer density we estimated deer density using line transect sampling that accounts for different detectability in March 2008 and 2009, respectively. We collected more than 8,600 ticks from roe deer heads and necks, 92.6% of which were Ixodes spp., 7.4% Dermacentor spp. Among Ixodes, 3.3% were larvae, 50.5% nymphs, 34.8% females and 11.4% males, with significant seasonal deviation. Total tick infestation was high, with considerable individual variation (from 0 to 270 ticks/deer). Adult tick burden was positively correlated with roe deer body indices (body mass, age, hind foot length). Significantly more nymphs were found on deer from forest departments with high roe deer density indices, indicating a positive correlation with deer abundance. Overall, tick burden was highly variable. Seasonality and large scale spatial characteristics appeared to be the most important factors affecting tick burden on roe deer

    Factors affecting patterns of tick parasitism on forest rodents in tick-borne encephalitis risk areas, Germany

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    Identifying factors affecting individual vector burdens is essential for understanding infectious disease systems. Drawing upon data of a rodent monitoring programme conducted in nine different forest patches in southern Hesse, Germany, we developed models which predict tick (Ixodes spp. and Dermacentor spp.) burdens on two rodent species Apodemus flavicollis and Myodes glareolus. Models for the two rodent species were broadly similar but differed in some aspects. Patterns of Ixodes spp. burdens were influenced by extrinsic factors such as season, unexplained spatial variation (both species), relative humidity and vegetation cover (A. flavicollis). We found support for the ‘body mass’ (tick burdens increase with body mass/age) and for the ‘dilution’ hypothesis (tick burdens decline with increasing rodent densities) and little support for the ‘sex-bias’ hypothesis (both species). Surprisingly, roe deer densities were not correlated with larvae counts on rodents. Factors influencing the mean burden did not significantly explain the observed dispersion of tick counts. Co-feeding aggregations, which are essential for tick-borne disease transmission, were mainly found in A. flavicollis of high body mass trapped in areas with fast increase in spring temperatures. Locally, Dermacentor spp. appears to be an important parasite on A. flavicollis and M. glareolus. Dermacentor spp. was rather confined to areas with higher average temperatures during the vegetation period. Nymphs of Dermacentor spp. mainly fed on M. glareolus and were seldom found on A. flavicollis. Whereas Ixodes spp. is the dominant tick genus in woodlands of our study area, the distribution and epidemiological role of Dermacentor spp. should be monitored closely
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