1,720,955 research outputs found
Possible effects of human impacts on epibenthic communities and coral rubble features in the marine Park of Bunaken (Indonesia)
No full textIndo-Pacific coral reefs are considered among the most complex and biodiversified ecosystems in the world. Their existence is threatened by both natural and anthropogenic factors. Therefore, the assessment of anthropogenic disturbances is necessary to protect and manage these marine natural resources. In Bunaken Marine Park (North Sulawesi, Indonesia) epibenthic assemblages and coral rubble features at four impacted sites (each of them located close to villages and frequently exploited as recreational diving spots), and four well preserved sites (far from villages and scarcely frequented by divers), were investigated at 6, 12 and 18 m depth, in order to identify possible reef modifications. The assemblages were sampled by way of photographs. Coral rubble cover was estimated both by way of photographs and along belt transects, while grain size and the living fraction of the coral rubble were assessed by direct samples. The data showed significant differences between the study sites and between depths with regard to human activity. The hard coral cover and the assemblage heterogeneity are higher in control sites than in the impacted site where, especially in shallow water, the mechanical damage can strongly affect the assemblage structure. The mean percentage of coral rubble cover was significantly higher in the impacted sites, while its living portion was higher in the controls. The fine fraction (0.1-0.5 cm) of coral rubble was more abundant in the impacted sites, coarse fraction (4-8 cm) prevailed at the control sites while intermediate fractions did not show any differences. The three-dimensional structural complexity of the assemblages was reduced in the sites affected by physical disturbances. These results are strongly independent of depth. Human activities, which damage corals and increase coral rubble production, are mainly performed on the reef flat and reef edge but their effects are transferred along the reef wall in depth. © 2009 Elsevier Ltd. All rights reserved
Host-shift speciation in Antarctic symbiotic invertebrates: further evidence from the new amphipod species Lepidepecreella debroyeri from the Ross Sea?
No full textLepidepecreella debroyeri n. sp. (Amphipoda, Lysianassoidea) is described from specimens collected at Terra Nova Bay (Ross Sea, Antarctica) in the framework of several scientific expeditions of the Italian National Antarctic Research Program. This amphipod is an obligate parasite of the regular sea urchin Sterechinus neumayeri (Meissner, 1900) and
also occurs at diving depths. L. debroyeri n. sp. shares with Lepidepecreella andeep Berge, Vader & Lockhart, 2004, an abyssal species described for the Weddell Sea, an almost identical morphology and ecological traits, being both associated with sea urchins of two different families. This close relationship could be the result of a host-shift phenomenon that occurred during the high number of glacial cycles, possibly rendering the preferred host unavailable. L.
debroyeri n. sp. shows a high degree of variation in terms of sex ratio and population structure between
different host specimens, a fact that could be related to a great mobility of this small parasitic amphipod. The new amphipod species is itself the subject of a hyperparasitic interaction, carrying tantulocarid crustaceans on the pleopods. This represents the first record of a symbiotic interaction between a tantulocarid and an amphipod for the Southern Ocean
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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