1,720,965 research outputs found
Heterogeneity of body size structure of detritus based guilds in the River Tirso basin (Sardinia, Italy).
No full textIfrane, Marocc
Effect of drought frequency and other reach characteristics on invertebrate communities and litter breakdown in the intermittent Mediterranean River Pula (Sardinia, Italy)
No full textBenthic invertebrate communities were sampled in spring and fall, and breakdown of reed litter was measured in winter, spring, summer and fall, at 23 sites in an intermittent Mediterranean river basin (Pula, Sardinia, Italy), and their variations were related to drought frequency and other reach characteristics (altitude, order, stream channel width and depth, vegetation cover, sediment type, organic content, and water quality). 78% of the sites were affected by drought events, mainly in summer and fall. Benthic taxonomic richness was higher and most taxa were more widely distributed in spring than in fall. Canonical correspondence analysis showed that measured environmental variables accounted for 72% of the variance in invertebrate community structure. Reed decay rates varied among seasons, and during the dry season among stream orders as well. Drought events slowed down breakdown and explained 44% of spatial variability in decay rates (Stepwise multiple regression analysis), an additional 8% being explained by water chemistry. Results suggest that drought events affect ecosystem functioning (litter breakdown) more than structure (invertebrate communities
Factors affecting macroinvertebrate guild distribution in a Mediterranean intermittent stream: Rio Pula (Sardinia, ITALY).
No full textSpatial analysis of plant detritus processing in a Mediterranean river type: the case of river Tirso (Sardinia, Italy).
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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
Spatial and temporal variations of detritus breakdown rates in the river Flumendosa basin (Sardinia, Italy)
No full textHere we analyse in a 5th order Mediterranean river (River Flumendosa, Sardinia, Italy) spatial and temporal variations of plant detritus processing, a key functional aspect of river ecosystems. Decay rates of dead leaves (Phragmites australis) were studied during the fall-winter and spring-summer seasons at 17 sites distributed among 5 stream orders. Litter decay rates varied more, and were higher in spring-summer than in fall-winter. On the spatial scale, patterns of decay rate variation among sites and orders did not vary between seasons; seasonal variation was low in reaches with slow rates and high in reaches with fast rates. Data analysis showed a spatial pattern of increasing reed detritus decay rates with increasing stream order
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