1,720,960 research outputs found
Ecological trajectories and plant community structure in side channels of the lower Loire River reach : connectivities, filters and strategies
No full textLes hydrosystèmes fluviaux ont fait l'objet de grands aménagements (endiguement, chenalisation, barrages) et d'exploitation de leurs alluvions, en particulier depuis l'époque industrielle. Ces modifications morphologiques du lit mineur déséquilibrent leur fonctionnement hydrosédimentaire ainsi que les biocénoses. Les chenaux latéraux sont particulièrement sensibles à ces modifications tandis qu'ils accueillent une importante part de la biodiversité alluviale. Pourtant leurs fonctionnements écologiques restent méconnus. Ce travail analyse les dynamiques de terrestrialisation (phénomène de remplacement des habitats aquatiques par des habitats terrestres) des chenaux latéraux en lien avec les connectivités hydrologiques et les ressources disponibles (nutriments, lumière). Les 15 sites d'étude situés sur la Loire aval (entre Montsoreau [49] et Nantes [44]), en contexte d'incision du lit, sont représentatifs du gradient de terrestrialisation. Les compartiments étudiés sont la végétation établie, les dépôts de diaspores et les banques de graines. Les résultats démontrent une prédominance de la végétation terrestre (vs. aquatique) dans ces chenaux et précisent l'effet du gradient de connectivité sur le phénomène de terrestrialisation et le processus de dispersion. Des interactions multiples entre la lumière, la granularité des sédiments et l'inondabilité, entre autres, structurent fortement les communautés végétales en termes d'espèces et de traits biologiques. Les études sur les diaspores laissent supposer une forte résilience de ces écosystèmes. De ce fait, les travaux visant à augmenter la connectivité des chenaux latéraux sont hautement encouragés pour limiter la terrestrialisation et pour soutenir une diversité d'habitats. Ils doivent cependant tenir compte des interdépendances entre les facteurs environnementaux.Since the industrial period, fluvial hydrosystems were largely impacted by dams, dykes or groynes and sediment mining. These morphological modifications unbalanced their hydrosedimentary functioning and biota. Side channels greatly contribute to the overall biodiversity of floodplains but they are particularly sensitive to hydromorphological modifications. Yet their ecological functioning remain largely unexplored. Present work analyzes terrestrialisation (i.e. transition from aquatic to terrestrial habitat) in side channels. The 15 study sites situated alongside the downstream reaches of the Loire River (from Montsoreau to Nantes, France), in bed incision context, are representative of the different terrestrialisation stages. The main focus was hydrological connectivity and available resources (nutrients and light), and how they structured standing vegetation, soil seedbank and deposited propagules. Results demonstrate the primacy of terrestrial (vs. aquatic) vegetation in side channels. They also refine how the connectivity gradient affects terrestrialization and dispersal processes. Multiple interactions between light, sediment grain size and flooding strongly shape plant communities with regard to their species composition and biological traits. Seed-related studies suggest for a strong resilience of these ecosystems. Hence, restoration efforts to increase side channels inner and outer connectivity are highly encouraged for the purpose of maintaining habitat diversity. They need however to take into account the interdependencies of environmental factors
Trajectoires écologiques et structuration des communautés végétales des chenaux latéraux en Loire aval : connectivités, filtres et stratégies
No full textSince the industrial period, fluvial hydrosystems were largely impacted by dams, dykes or groynes and sediment mining. These morphological modifications unbalanced their hydrosedimentary functioning and biota. Side channels greatly contribute to the overall biodiversity of floodplains but they are particularly sensitive to hydromorphological modifications.Yet their ecological functioning remain largely unexplored.Present work analyzes terrestrialisation (i.e. transition from aquatic to terrestrial habitat) in side channels. The 15 study sites situated alongside the downstream reaches of the Loire River (from Montsoreau to Nantes, France), in bed incisioncontext, are representative of the different terrestrialisation stages. The main focus was hydrological connectivity and available resources (nutrients and light), and how they structured standing vegetation, soil seedbank and depositedpropagules.Results demonstrate the primacy of terrestrial (vs. aquatic) vegetation in side channels. They also refine how theconnectivity gradient affects terrestrialization and dispersal processes. Multiple interactions between light, sediment grainsize and flooding strongly shape plant communities with regard to their species composition and biological traits. Seed-related studies suggest for a strong resilience of these ecosystems.Hence, restoration efforts to increase side channels inner and outer connectivity are highly encouraged for the purpose of maintaining habitat diversity. They need however to take into account the interdependencies of environmental factors.Les hydrosystèmes fluviaux ont fait l’objet de grands aménagements (endiguement, chenalisation, barrages) et d’exploitation de leurs alluvions, en particulier depuis l’époque industrielle. Ces modifications morphologiques du lit mineurdéséquilibrent leur fonctionnement hydrosédimentaire ainsi que les biocénoses. Les chenaux latéraux sont particulièrement sensibles à ces modifications tandis qu’ils accueillent une importante part de la biodiversité alluviale. Pourtant leurs fonctionnements écologiques restent méconnus.Ce travail analyse les dynamiques de terrestrialisation (phénomène de remplacement des habitats aquatiques par des habitats terrestres) des chenaux latéraux en lien avec les connectivités hydrologiques et les ressources disponibles (nutriments, lumière). Les 15 sites d’étude situés sur la Loire aval (entre Montsoreau [49] et Nantes [44]), en contexte d’incision du lit, sont représentatifs du gradient de terrestrialisation. Les compartiments étudiés sont la végétation établie, les dépôts de diaspores et les banques de graines.Les résultats démontrent une prédominance de la végétation terrestre (vs. aquatique) dans ces chenaux et précisent l’effet du gradient de connectivité sur le phénomène de terrestrialisation et le processus de dispersion. Des interactions multiples entre la lumière, la granularité des sédiments et l’inondabilité, entre autres, structurent fortement les communautés végétales en termes d’espèces et de traits biologiques. Les études sur les diaspores laissent supposer une forte résilience de ces écosystèmes.De ce fait, les travaux visant à augmenter la connectivité des chenaux latéraux sont hautement encouragés pour limiter la terrestrialisation et pour soutenir une diversité d’habitats. Ils doivent cependant tenir compte des interdépendances entre les facteurs environnementaux
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
