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Benthic assemblages and temperature effects on Paracentrotus lividus and Arbacia lixula larvae and settlement
No full textRecruitment is a principal controlling factor in population dynamics of marine species. In marine
invertebrates with a planktonic larval stage, such as echinoids, recruitment is assured by larval supply,
settlement and juvenile survival. Larval supply and juvenile survival are affected by a wide range of factors,
including temperature, presence of predators, quality and quantity of food. Echinoid larval settlement is
mainly conditioned by the finding of a suitable substrate to metamorphose. The sea urchins Arbacia lixula and
Paracentrotus lividus are considered key species of the Mediterranean infralittoral rocky shores. At high
densities, the grazing activity of both species can produce and maintain barren grounds, a particular habitat
condition characterized by extremely low cover values of erect algae with high presence of naked substrates
and encrusting corallinales, poor in biodiversity and ecosystem functions. We tested the role of different
settlement substrates on the metamorphosis competent larvae of the two species. Furthermore, from our
larval rearing trails we were able to identify strong temperature effects on larval development of the two
species. P. lividus and A. lixula larvae have been reared at 18 °C but for the second species it was necessary to
use higher temperatures (22 °C) to perform settlement experiments, as in the 18 °C set all larvae died in the
first week. Both species larvae have been fed Cricosphaera elongata. Metamorphosis of competent larvae has
been induced using different substrates: naked stones, Lithophyllum incrustans, Stypocaulon scoparium,
Corallina elongata, turf forming algae and Posidonia oceanica. For each species, two larval batches were used
for settlement experiments; for each larval batch two replicates/substrates were set up. No differences in the
rate of metamorphosis on any of the tested substrates were observed for P. lividus, while A. lixula showed to
prefer naked stones and encrusting coralline algae Considering that A. lixula population growth may trigger
barren extension on rocky shores, this may lead to a positive feedback between barren extension and A. lixula
population density. Furthermore, our results suggest that the predicted rise in seawater temperature may
favor A. lixula larval survival and inhibit P. lividus. Combining information on temperature tolerance with
other sources of information for these species in the Mediterranean, it is possible to develop a conceptual
model of the interaction between the two species and the alternative state of their habitats
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
Biologia dello sviluppo
No full textsviluppo biologico come un processo analitico, principi dello sviluppo, moderni strumenti applicati a problemi di base dello svilupp
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
Nuclear abnormalities in circulating erythrocytes in the teleostean fish Scorpena notata from contaminated sites in Ligurian Sea
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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
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