1,720,977 research outputs found
Distribution of native and non-indigenous bivalves and their settlers along an urban gradient
Get PDFMarine coastal habitats are often characterized by strong gradients of anthropogenic disturbance such as pollution, typically most severe at urban waterfronts. These variations create stress for local organisms leading to their distribution along the disturbance as a function of their tolerance. non-indigenous species (NIS) are considered more tolerant to anthropogenic disturbances than their native counterparts, thriving in urban areas, where native species are sparser. It is however not yet entirely clear if these distribution patterns are due to larval behavior and preferential settlement or post-settlement processes. In the present study, we investigated the abundance of adults and settlers of two native (Ostrea edulis, Mytilus galloprovincialis) and two non-indigenous (Magallana gigas, Xenostrobus securis) bivalves along a strong marine urban environmental gradient. Oysters had sparse abundances of both adults and settlers at all sites, with no obvious distributional gradients. The two mussel species showed different settler-adult distributions along the gradient. Both settlers and adults of the native mussel M. galloprovincialis strongly decreased moving from the outermost periurban site to the innermost urban site, consistent with preferential settlement of larvae according to environmental conditions. The non-indigenous adult mussel X. securis showed a distribution pattern opposite to that of M. galloprovincialis, markedly increasing in abundance from the outermost to the innermost site. This was not paralleled by the distribution of X. securis settlers, which established over a larger area, including sites where adults were essentially absent. The mismatch between settler and adult distributions for X. securis suggests that post-settlement factors dictate spatial adult distribution
Diversité et fonctionnement des communautés portuaires. Influence des espèces introduites dans un contexte de changement climatique
No full textLes infrastructures marines offrent des nouveaux substrats, colonisés par divers organismes (biofouling), mais qui diffèrent des habitats naturels par leurs filtres environnementaux et processus écologiques, leur composition biotique et leur grande diversité/abondance d’espèces non indigènes (ENI). L’artificialisation dans les marinas modifie l’hydrodynamisme, favorisant la concentration de perturbations humaines (p. ex. polluants). Des gradients peuvent être présents, avec une intensité plus élevée des perturbations dans les parties les plus internes des marinas, constituant ainsi un filtre sélectif pour les organismes. Ce travail visait à comprendre la diversité et le fonctionnement des communautés sessiles des marinas en étudiant l‘impact des gradients de perturbation sur leurs structures de l’entrée vers le fond plus perturbé. Constituant un défi sociétal important, les ENI étaient au cœur du sujet. Une approche expérimentale (transplantation réciproque) dans six marinas de deux régions (Méditerranée, Atlantique) a révélé que les différences dans la structure des communautés est causée par les niveaux locaux de pollution, associées à de l’adaptation locale à petite échelle spatiale (<100m). D’autres processus peuvent affecter ces dynamiques comme les interactions biotiques (prédation) et les perturbations sporadiques (vagues de chaleur). Dans le contexte du changement climatique, nous avons testé comment un réchauffement prévu de la mer (+3°C) impacte les communautés des marinas et favoriserait les ENI. Ces résultats visent à comprendre comment les perturbations dans les écosystèmes urbains marins affectent la biodiversité et en particulier la prévalence des ENI.Marine infrastructures offer new substrates, colonized by a variety of organisms (biofouling), but are different from natural habitats since environmental filters and ecological processes differ, biotic composition differs from natural habitats, and they are characterized by a high diversity and abundance of non-indigenous species (NIS). Artificialization in marinas modifies hydrodynamism, affecting the water column characteristics like temperature and favoring the concentration of anthropic disturbances like pollutants. Environmental gradients may be present, with higher levels of disturbance in the innermost parts of marinas, acting as selective filters for organisms. The present work aimed to understand the diversity and functioning of sessile communities in marinas by studying how disturbance gradients shape community structure and function between the entrances of marinas and their more disturbed inner parts. A particular focus laid on NIS, which are common in marinas and constitute an important societal challenge. An experimental approach (reciprocal transplant) in six marinas from two regions (Mediterranean, Atlantic), revealed that differences in community structure are caused by local pollution levels, associated to local adaptation at small spatial scale (<100m). However, other processes might affect these dynamics like biotic interactions (predation) and pulse disturbances (heat waves). In the context of climate change, we also tested how projected seawater warming (+3°C) may impact marina communities and might favor NIS. These results might help understanding how disturbances in marine urban ecosystems drive biodiversity and especially the prevalence of NIS
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
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