1,721,024 research outputs found
Short-term versus long-term changes in the benthic communities of a small coastal lagoon: implications for ecological status assessment
No full textThe characteristic high variability and low predictability of coastal lagoons, due
to strong changes in marine and freshwater inputs, make these ecosystems an interesting casestudy.
The small Melides landlocked coastal lagoon in SW Portugal is a paradigmatic example,
with a biological community highly stressed by these phenomena. Benthic macroinvertebrate samples were collected in 1998/99 and 2009 and each year, in different seasons and addressing different environmental conditions influenced by the connection to the sea and rainfall regime.
Major spatial and temporal patterns in benthic communities were investigated using some invertebrate attributes (e.g. community composition, density, species richness and diversity). A very low taxonomic species richness and diversity was found in the Melides lagoon and only a much reduced number of species occurred along all sampling periods and in both sampling campaigns.
Although the colonization events play a crucial role, the persistence of the observed species was mainly associated to abiotic factors, such as salinity, temperature and dissolved oxygen. Despite the potential reduction in anthropogenic pressure, by the construction of a sewage treatment plant and a reduction of urban occupation, the ecological status did not improve and the high level of natural environmental variably in the lagoon seems to be the dominant stressor influencing benthic invertebrate communitie
Diversity and environmental control of Prasinoviruses (Phycodnaviridae)
No full textLes virus sont les entités les plus abondantes dans les océans et ces parasitoïdes interagissent avec chaque composante de la biosphère marine, soit par la sélection des communautés d'hôte, soit en influençant les cycles biogéochimiques. Cependant, l'impact des conditions environnementales sur ces assemblages viraux complexes est encore mal compris. L'objectif de ce travail est de comprendre comment les assemblages viraux sont influencés par les facteurs environnementaux. Durant un suivi mensuel des communautés de mars 2013 à avril 2014, nous nous sommes intéressés à un système hôte-virus abondant et largement répandu, les communautés de microalgues Mamiellophyceae et leurs Prasinovirus. Durant ces études, des approches de PCR quantitative et de séquençage massif ont été développées afin de décrire les populations environnementales présentes au sein du Golfe du Lion. Les populations de Mamiellophyceae dominent le compartiment des picoeucaryotes photosynthétiques, avec des dynamiques fortes au cours de l'année. Les communautés de Prasinovirus reflètent les dynamiques de leurs hôtes, elles-mêmes en lien avec les facteurs environnementaux. En revanche, la dispersion ainsi que le maintien des virions semblent directement impacté par les conditions environnementales, comme la température et l'hydrodynamisme. Certains groupes viraux, comme les virus d'Ostreococcus, sont inféodés aux lagunes et aux zones côtières, suggérant ainsi que la dispersion des populations virales est limitées par la présence des hôtes.Viruses are the most abundant biological entities in oceans and they every member of the marine biosphere is affected by them, they influence the composition of communities and influence biogeochemical cycles. However, the influence of environmental conditions on complex viral populations is still poorly understood. The aim of this study is to understand how environmental factors influence viral communities. We followed viral communities monthly from March 2013 to April 2014 and investigated the host-virus system of Mamiellophyceae communities and their prasinoviruses, a model sytem that is abundant and widespread. Prasinovirus-host populations from the Gulf of Lion were quantified by PCR amplification and analysis of genetic marker genes and high throughput sequencing. Photosynthetic populations of picoeukaryotes were dominated by populations of Mamiellophyceae showing high levels of quantitative and qualitative annual variations that were related to environmental factors. Prasinovirus communities mimed host dynamics, but viral dispersion and persistence appeared to be impacted directly by environmental conditions such as temperature and hydrodynamics. Several viral groups, such as Ostreococcus viruses, were specific to lagoonal and coastal areas, suggesting that their dispersal is limited by host occurrence
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
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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