1,720,957 research outputs found
Biogeography and relevant ecological drivers in spring habitats: A review on ostracods of the Western Palearctic
No full textSprings are relevant environments from an ecological point of view. The microhabitat-mosaic structure of these ecotones often harbors high biodiversity. Due to the temperature stability of permanent springs and to the persistence over geological time scales of their aquifers, these environments may act as refugia and as potential speciation sites for aquatic fauna. In this study, we review the current knowledge on the diversity and distribution of ostracods associated with ambient springs in the Western Palearctic area, and on the ecological factors that have been reported to affect their occurrence. Literature mining revealed 37 papers, allowing to gather information on 92 ostracod taxa belonging to 31 genera, found in 612 springs out of a total of 743. More detailed information available from 20 studies carried out in the Central-Eastern Alps and Northern Apennines allowed us to conduct a focus study on a more restricted geographic area. Several species have very low frequency, occurring in just one or two springs. Rare or endemic species were frequent, whilst only one non-native species (Chlamydoteca incisa) was found. Species richness varied from 1 to 9, and it was greater in pool springs than in flowing springs and seepages. Correspondence analysis on the presence-absence data unveiled biogeographical patterns in spring ostracod community composition. The variation in community composition was partly organised along altitudinal, latitudinal, water-temperature, and conductivity gradients, and spring typologies affected assemblage structure as well. Springs are important areas for biodiversity conservation at the continental and regional scale. Nevertheless, relatively few investigations have dealt with the human impacts on springs and their biota, and conservation guidelines are largely missing
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
Are aquatic assemblages from small water bodies more stochastic in dryer climates? An analysis of ostracod spring metacommunities
No full textMetacommunity ecology describes community organisation considering both environmental and spatial processes. We tested the relative importance of environmental and spatial factors on spring ostracod assemblages from four European regions characterised by different climatic conditions (e.g. aridity). Pure and shared effects of environment and space were calculated using redundancy analysis and variation partitioning. Both environmental and spatial variables significantly explain assemblage variation, although with different relevance among areas. The amount of variation explained by environmental factors decreased with increasing climate aridity. The reduced size of spring habitats makes them prone to drying events, which are more frequent in dryer climates. Frequent disturbances may lead to local extinctions followed by colonisations from nearby sites, in a source–sink dynamics. Early recolonisation leads to random assemblages and reduces the match between organisms and environmental conditions. As a consequence, a low amount of community variation can be explained by environmental variables. Conversely, the settled communities from wetter climates best fit the ecological characteristics of sites, and deterministic processes, such as species sorting, dominate the assemblages. In conclusion, in the studied regions, ostracod communities from small water bodies of dryer climates seem to be mainly driven by stochastic dynamics when compared to more continental areas
Is there an ideal protocol for sampling macroinvertebrates in springs?
Get PDFSampling in springs has several technical problems due to their reduced dimensions and habitat heterogeneity. A standardized quantitative method for sampling crenic macroinvertebrates has never been proposed. The aim of this study was to compare different sampling methods and consider their environmental impacts. First, we present a review of sampling methods found in the literature and discuss their advantages and disadvantages with respect to selective collection of the target community and habitat disturbance. Altogether, 10 different methods have been reported, the use of nets being the most common protocol. Second, we report the results of macroinvertebrate samplings performed in three springs, each surveyed twice, using three different methods (multi-habitat proportional hand net, baited traps, and vegetation washing), in order to compare their effectiveness in collecting macroinvertebrates. Overall, 32 macroinvertebrate taxa, mostly identified at family level, were collected in the sampled springs. Significant differences in abundances were found using different methods, while results for community structure were comparable between the hand net sampling and the combined use of the other two methods, notwithstanding slight differences in the composition of Coleoptera and Diptera assemblages. The hand net, with a multi-habitat proportional approach, yielded more thorough results, making it suitable for biodiversity inventories but having some potentially negative effects on spring habitats. Traps and vegetation washing are also reliable methods with negligible impacts on spring ecosystems that can be conveniently used in ecological studies
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
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