1,720,969 research outputs found
Influence des gradients environnementaux sur la structure des communautés endobenthiques du système du Saint-Laurent
No full textTitre de l'écran-titre (visionné le 25 juillet 2023)Les organismes benthiques jouent des rôles importants dans les écosystèmes aquatiques tels que l'oxygénation, la décomposition ou le recyclage de la matière organique. Toutefois, les pressions environnementales et anthropiques croissantes menacent le bon fonctionnement de ces systèmes et engendrent une baisse de la diversité benthique, qui mériteraient d'être mieux documentées. Le Saint-Laurent, considéré comme l'un des plus grands systèmes hydrographiques au monde, présente une mosaïque d'habitats variés, de forts gradients environnementaux et de nombreuses pressions humaines, tous susceptibles d'influencer les communautés benthiques à divers degrés. Cette étude s'est intéressée à trois régions hydrologiques du Saint-Laurent : la portion fluviale, l'estuaire fluvial et l'estuaire moyen. L'objectif était de caractériser la composition et la répartition des différentes communautés benthiques dans une portion contrastée du système Saint-Laurent et d'identifier les variables environnementales qui expliquaient le mieux leur présence. Les communautés benthiques ont été échantillonnées à 113 stations de Montréal à Cacouna de 2018 à 2020. Les embranchements Annelida et Arthropoda étaient les deux taxons les plus représentés dans notre échantillonnage. Les analyses de groupement ont révélé neuf communautés benthiques influencées par les gradients environnementaux propres des régions hydrologiques. Les masses d'eau, la salinité, la nature des sédiments ainsi que la température étaient les quatre variables clés qui expliquaient 16 % de la relation entre les communautés et les variables environnementales. Cette étude a mis en évidence les effets de processus régionaux sur la structure des communautés benthiques et suggère l'implication de plusieurs effets locaux. Enfin, c'est la première fois qu'une étude portant sur les communautés benthiques couvre à la fois le fleuve et l'estuaire du Saint-Laurent. Ce travail à grande échelle permet d'affiner la compréhension de l'écosystème et contribue à améliorer la pertinence des indicateurs benthiques.Benthic organisms play important roles in aquatic ecosystems such as oxygenation, decomposition, or recycling of organic matter. However, growing environmental and anthropogenic pressures threaten the proper functioning of aquatic environments and lead to a decline in benthic diversity, which deserves to be better documented. St. Lawrence, considered one of the largest hydrographic systems in the world, presents a mosaic of varying habitats, strong environmental gradients, and numerous human pressures, all likely to influence benthic communities to varying degrees. This study focused on three hydrological regions of St. Lawrence: the fluvial portion, the fluvial estuary, and the upper estuary. The objective was to characterize the composition and distribution of different benthic communities in a contrasting portion of the St. Lawrence system and to identify the environmental variables that best explained their presence. Benthic communities were sampled at 113 stations from Montreal to Cacouna between 2018 and 2020. The phyla Annelida and Arthropoda were the two most represented taxa in our sampling. Cluster analyses revealed nine benthic communities influenced by hydrological region-specific environmental gradients. Water masses, salinity, nature of sediment, and temperature were the four key variables that explained 11% of the relationship between communities and environmental variables. This study has highlighted the effects of regional processes on the structure of benthic communities and suggests the involvement of several local effects. Finally, this is the first time that a study on benthic communities has covered both the St. Lawrence River and the estuary. This large-scale work makes it possible to refine the understanding of the system and contributes to improving the relevance of benthic indicators
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Caractérisation de la structure génétique de populations et évaluation de ses déterminismes environnementaux chez le grand brochet (Esox lucius) dans le système lac Ontario - fleuve Saint-Laurent
No full textNous avons documenté la génétique du paysage du grand brochet (Esox lucius) en nous basant sur l’analyse de 22 microsatellites, incluant 10 nouveaux marqueurs développés ici, dans le système lac Ontario – fleuve Saint-Laurent. La structure génétique des populations était globalement très faible mais spatialement variable ; le niveau moyen de différenciation génétique dans la section amont (Ontario) de l’aire d’étude était trois fois plus important que celui observé dans le secteur aval (Québec). Vingt variables environnementales furent considérées et les différentes masses d’eau, la présence de barrages et la stabilité interannuelle du niveau d’eau s’avérèrent positivement associées à l’intensité de la différenciation génétique. Une importante variation du niveau d’eau influe sur la qualité et la localisation annuelle des habitats de reproduction du grand brochet, l’instabilité locale de l’habitat prenant la forme d’une variation interannuelle du niveau d’eau semble localement inhiber la structure génétique de populations, probablement en empêchant la philopatrie. Mots clés : Esox lucius, grand brochet, génétique du paysage, structure génétique de populations, variation environnementale, stabilité de l’habitat, marqueurs microsatellites, gestion, conservation.In this study, we documented the landscape genetics of northern pike (Esox lucius) based on the analysis of 22 microsatellites, comprising 10 markers developed for the purpose of this study, in the Lake Ontario – St. Lawrence River system. Population genetic structure over the whole study area was globally very weak but spatially variable with mean level of differentiation in the upstream (Ontario) section of the studied area being three-fold higher than observed in the downstream (Québec) sector. Twenty environmental variables were considered and different water masses, dams’ presence and inter-annual water level stability were positively associated to the extent of genetic differentiation. Since high water level variation impacts on yearly quality and localization of northern pike spawning habitats, local habitat instability which is under the form of inter-annual water level variation seems to locally impede population genetic structure, perhaps by inhibiting philopatry behavior. Keywords: Esox lucius, northern pike, landscape genetics, population genetic structure, environmental variation, habitat stability, microsatellite markers, management, conservation
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
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