1,720,954 research outputs found
Soft-bottom intertidal ecosystems shaped by ecosystem engineers : consequences for trophic structure
Get PDFInter-getijde kustgebieden met zandige bodem worden gevormd door biobouwers:
Gevolgen voor de trofische structuur
Biobouwers zijn soorten die hun omgeving sterk veranderen. Door dit te doen, kunnen ze ze het aantal en de verspreiding van andere soorten beïnvloeden. Met monitoren en experimenten in het veld, hebben we de effecten van biobouwers op de gemeenschap van soorten in inter-getijde kustgebieden met zandige bodem onderzocht. We vonden dat de aanwezigheid van rifvormende schelpdieren (d.w.z. mosselen en oesters), zeegras en krabben, het aantal soorten en de samenstelling van de voedselketen sterk kunnen veranderen, zowel in de ruimte als over de tijd. Door het verstrekken van structuur en het stabiliseren van de bodem, kunnen rifvormende schelpdieren namelijk meerdere voedselketen-niveaus beïnvloeden en deze effecten zijn zichtbaar tot op honderden meters buiten de grenzen van het rif zelf. Daarnaast spelen de effecten van deze rifvormende schelpdieren in combinatie met andere interacties zoals predatie en competitie, ook een sterke rol in het structureren van populaties van andere soorten schelpdieren, zoals kokkels. Interessant is ook dat koloniserend zeegras dat fijn sediment invangt, in combinatie met gravende krabben die grote poelen maken in deze sedimentlaag, ervoor zorgen dat de structuur van de voedselketen en de temporele ontwikkeling hiervan drastisch veranderen. De bevindingen van dit onderzoek onderstrepen het grote belang van biobouwers in inter-getijde kustgebieden met een zandige bodem.
Soft-bottom intertidal ecosystems shaped by ecosystem engineers
Consequences for trophic structure
Ecosystem engineers are species that strongly change their environment. By doing so, they can affect the abundance and distribution of other species. With field surveys and experiments, we studied the effects of ecosystem engineers on the community of species in soft-bottom intertidal coastal areas. We found that the presence of ecosystem engineers such as reef-building bivalves (i.e. mussels and oysters), seagrass and crabs, strongly changed the number of species and the composition of the foodweb in these areas both in space and time. Specifically, by providing structure and by stabilizing the sediment, reef-building bivalves can influence multiple foodweb levels and these effects can range up to 100s of meters beyond reef boundaries. In addition, ecosystem engineering effects of reef-building bivalves in combination with other type of interactions such as predation and competition, strongly structure the population of other bivalve species in these areas such as cockles. Furthermore, colonizing seagrass patches that accumulate silt, and burrowing crabs that create large intertidal pools in this accumulated silt layer, dramatically alter food web structure and its temporal development (>10y). Overall, the findings of this study underline the importance of ecosystem engineers in structuring soft-bottom intertidal communities over large areas and long timescales.
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
- …
