1,720,992 research outputs found
The Diaptomidae (Copepoda, Calanoida) of Tunisia and the role of spatial and environmental factors as drivers of their distribution patterns
Full text linkEven in a biodiversity hotspot such as the Mediterranean basin, aspects relating to the distribution of some groups of microcrustaceans still need clarification. In this paper, we critically analyse the available information on diaptomid copepods in Tunisian inland waters and, based on the largest sampling campaign to date carried out in the country, report new data on their distribution. In the frame of this study, 248 crustacean samples were collected from 190 sites, and 10 diaptomid species belonging to 7 genera and 2 subfamilies were found in the samples. Their distribution follows a climate gradient determined by precipitation, and ecological variables mainly affect diaptomid distribution in the study area, while pure spatial factors are of negligible importance. Diaptomid biodiversity is therefore strongly linked to the diversity of inland waters that characterise the country. This is especially true in the wetlands of the Medjerda alluvial plain, where six diaptomid species co-occurred sympatrically, with up to four or five species coexisting syntopically and synchronically in some sites. Unfortunately, the natural water bodies of this plain are currently strongly threatened by urban expansion and agricultural reclamation, and the risk of local extinction for the species they host is increasingly high
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
Study of cysts of Artemia salina (Leach 1819) in the salines of Megrine - Tunisia
No full textThe qualitative and quantitative study of Artemia salina L. 1819 cysts in the salines of Megrine since May 1985 until May 1986 includes that the occurrence of the cysts is influenced directly by the biotic and abiotic factors.L'étude qualitative et quantitative des oeufs d'Artemia salina L. 1819 en provenance des salines de Mégrine de mai 1985 à mai 1986 a montré que leur production est directement liée aux facteurs biotiques et abiotiques du milieu.Publishe
Larvae of Teleostean fishes captured in the Gulf of Tunis.
No full textThirteen species of Teleostean fish larvae attributed to 10 families are recorded in the Gulf of Tunis. Gilt and Anchovy larvae predominate.Treize types de larves alécithes apparentées à dix familles de poissons téléostéens ont été inventoriées dans le Golfe de Tunis. Les larves d'engraulidés et de clupéidés ont été les plus nombreuses dans les échantillons récoltés.Publishe
Biological observations on Artemia in the salt works of Megrine
No full textBiological observations relative to Artemia population composition and the mode of reproduction have been realized in the saltworks of Megrine from January to June 1987.Des observations biologiques portant sur la composition de la population d'Artemia ainsi que sur son mode de reproduction ont été réalisés dans les salines de Mégrine de janvier à juin de l'année 1987.Publishe
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