1,720,959 research outputs found
Near anoxia and sulphide as possible factors influencing the spatial distribution of Acartia tonsa and Acartia clausi: comparative evaluation of egg tolerance
No full textIn many coastal and estuarine areas the planktonic copepods Acartia tonsa and Acartia clausi show a spatial separation with A.
tonsa restricted to brackish waters and confined environments and A. clausi inhabiting areas more influenced by sea water. The
hatching and viability of A. tonsa and A. clausi eggs exposed to anoxia and anoxia/sulfide (conditions that are frequent in bottom
waters of the most confined areas) was evaluated to determine if these stress factors play a role in the distribution of these species.
Subitaneous eggs, spawned by laboratory reared organisms, were incubated in near anoxia (<7.59×10−3 mmol O2 L−1) or anoxia/
sulfide (∼1 mmol L−1) for different periods (1, 4, 8 and 15 days), then transferred to normoxic conditions. The exposure of the
eggs to near anoxia and sulfide appears to induce the same response (quiescence) in both species. Exposure times ≤8 days to near
anoxia or anoxia/sulfide did not affect egg viability, while 15 day exposure caused significant declines in hatching success of both
species. A significant difference between the effects of near anoxia and anoxia/sulfide was observed when incubation lasted
15 days; hatching of eggs exposed to sulfide being higher than that of eggs exposed to near anoxia for both species. No significant
differences were observed between the two species in hatching success of eggs exposed to both near anoxia and anoxia/sulfide
(with the exception of eggs incubated in near anoxia for 4 days). The results indicate that the impact of anoxia and sulfide on the
eggs of the two Acartia species cannot be a factor explaining the spatial distribution in coastal and brackish environments of these
copepods.
Feeding experiments on A. clausi were also performed. Suitability of different algal species to rear this copepod was evaluated
and the results were compared with data previously obtained for A. tonsa. Differences in feeding needs between A. clausi and A.
tonsa are discussed
Messa a punto di una metodologia di saggio a 14 giorni su Artemia franciscana e A. parthenogenetica.
No full text
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
Hypoxia and starvation tolerance in individuals from a riverine and a lacustrine population of Darwinula stevensoni (Crustacea: Ostracoda)
No full textVariations 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
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