1,720,983 research outputs found
Temporal dynamics and biomass partitioning in three Adriatic seagrass species: Posidonia oceanica, Cymodocea nodosa, Zostera marina
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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
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
“Anthurid invasion” along the Mediterranean coasts: the spreading of Mesanthura cfr. romulea and Paranthura japonica
No full textThe Anthuroidea is a superfamily of elongated isopods belonging to the mesofauna, mainly distributed in the austral hemisphere and able to colonize a variety of benthic habitats. In recent years, two species from the families Anthuridae and Paranthuridae have been reported as non-indigenous in the Mediterranean Sea: one species of Mesanthura, most likely conspecific with Mesanthura romulea native to Australia, and Paranthura japonica, native to the Asian Western Pacific. Both these species were initially recorded along the Italian coasts, in the harbour of Salerno (2000) and in the Lagoon of Venice (2005), respectively. Since these recordings, their distribution has been considerably expanding. In this study, we present an update on their current known distribution in the Mediterranean Sea from literature records and unpublished data acquired from a range of surveys conducted by the authors across the Mediterranean Sea. Thus far, M. cf. romulea has been found in 13 Italian localities, and dubiously in Tunisia. M. cf. romulea was found in harbours and marinas, as well as in natural habitats (such as seagrass meadows and algal canopies), suggesting shipping as the most likely vector of introduction and highlighting its capability of further expansion both by natural spread or secondary translocation. Furthermore, P. japonica has been reported in 19 localities from four countries (Italy, France, Greece and Tunisia), in several important shellfish farming localities (Venice, Taranto, Olbia, La Spezia, near Thau Lagoon), suggesting aquaculture to be the main vector of introduction for this non-indigenous species. In addition, the subsequent findings for these two species in ports and on boat hulls highlights the role of vessel traffic in their further spread across the Mediterranean.
Despite their different introduction histories, the simultaneous occurrences of these non-indigenous anthurids in numerous Mediterranean localities may stem either from their recent spread in the basin, or from an improvement in taxonomic expertise. Since anthurid isopods are from a taxonomically challenging taxon, these two non-indigenous species may have gone either unnoticed or misidentified for a long time
Benthic associations of the shallow hard bottoms off Terra Nova Bay, Ross Sea: zonation, biomass and population structure
No full textQuantitative and semi-quantitative samples of phyto- and zoobenthic organisms were collected by SCUBA diving at five stations along a depth transect from 0.5-16 m on the shallow hard bottoms off Terra Nova Bay, Ross Sea, Antarctica. The benthic associations were dominated by two macroalgal species (Iridaea cordata and Phyllophora antarctica) and by few animal taxa (mainly polychaetes, molluscs and peracarid crustaceans). Distribution at the community and species levels revealed a well-defined zonation pattern as a function of depth, governed mainly by sea ice scouring and melting. Zonation of vagile fauna was also affected by the effects of covering and architecture of the two dominant macroalgae. Species richness and diversity were higher in the Phyllophora-associated community, where habitat complexity and sheltering were higher. The highest faunal abundance (over 82 000 ind.m(-2)) and biomass (macroalgae and fauna wet weight 2392 g m(-2)) were recorded at 2 m depth in association with the Iridaea covering, where the harsher environmental conditions select a few taxa. The biomass values, even if underestimates of the whole community standing crop, are among the highest recorded in shallow austral biotopes. An autoecological and demographic analysis of the most abundant animal species revealed for some species (e.g. Laevilitorina antarctica and Paramoera walkeri) a quite complex population structure with up to three size classes, including juveniles. In some species, the cohort of juveniles showed a well defined depth preference probably related to sheltering by the macroalgae. As a whole, the species analyzed showed various and contrasting reproductive strategies, despite the fact that the environmental conditions along the transect were relatively similar and quite selective
Depth and Seasonal Distribution of Some Groups of the Vagile Fauna of the Posidonia oceanica Leaf Stratum: Structural and Trophic Analyses
No full textThe taxonomical and trophic structures of the vagile fauna communities of the leaf stratum in a Posidonia oceanica meadow at Ischia (Gulf of Naples, Italy) were investigated at five stations along a depth gradient (1 to 25 m). Sampling was performed in July, November, February, and May. The analyzed groups - polychaetes, molluscs, tanaids, isopods, amphipods, and decapods - exhibited similar distributional trends in all seasons, with coenotic discontinuities occurring at well-defined depths. The same zonation pattern was produced by feeding-guild analysis. Eleven trophic groups were identified. The most abundant groups were: Herbivores, which were found mainly at the shallow stations; Herbivores-deposit feeders, which were widely distributed along the transect; Deposit feeders-carnivores, found mainly at the deep stations.This study suggests that in the Posidonia leaf stratum, herbivores and herbivores-deposit feeders, as consumers of epiphytic micro- and macroflora and deposited particulate organic matter, play an important role in the energy transfer from producers to higher trophic levels of the system
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