1,720,970 research outputs found
Molecular characterization of 18S rDNA partial sequence in Microcosmus (Stolidobranchiata, Pyuridae)
No full textWe present a 18S rDNA based molecular phylogeny of two species of the genus Microcosmus (M. sulcatus and M. claudicans) sampled in the Mediterranean, to investigate their phylogenetic position relative to species of the order Stolidobranchiata. The analysis is based on partial sequences (739 bp) of the 18S rDNA. Among the 18 variable sites found between the two species, 4 correspond to transi- tions (ts), 14 to transversions (tv) and 4 to deletions/insertions. In the considered Stolidobranchiata, we found 4.3% overall mean number of nucleotide differences and 0.06 (S.E. ±0.01) Kimura 2-parameter distance. The mean number of nucleotide differences between Microcosmus spp. and other Stolido- branchiata species was of 6% and 0.08 (S.E. ±0.01) Kimura 2-parameter distance. A molecular phyl- ogeny obtained by Maximum Parsimony corroborates results of the traditional taxonomy
Rock Partridge Alectoris graeca a good candidate for anumbrella species in rocky mountains in Italy
No full textThe umbrella concept is often applied in conservation management but as yet has rarely been tested empirically. Alectoris graeca is endemic in Europe, occurring only in the Balkans, the Alps and the Apennine Italian mountains. This species could be considered a good example of an umbrella species, that is one whose presence can imply broader biodiversity interest. Its European breeding population is relatively small and has undergone a large decline since about 1950 having suffered from habitat fragmentation and loss. The current approach for maintaining viable populations supports management of the species’ habitat. We suggest that this conservation approach for the single species can also favor some other sympatric bird species and biodiversity in general. During 2004-2006, Rock Partridge and its companion bird community were censused in nine study areas from Cilento and Vallo di Diano National Park (Southern Italy). The study area consisted of dry and open rocky mountain with grassy patches and low scrubs from 1000 to 1900 m a.s.l. The classification of each site using a model of habitat suitability (including scores for various environmental traits) highlighted some significant relationships between Rock Partridge presence / abundance and suitable habitat on the other side. The species was present in seven out of nine study areas, where the suitability was optimal or good; in the remaining two areas we found a lower value of suitability. In the seven positive sites we also found the highest values of species richness of mountain bird community, ranging from 31 to 62 species: species richness values appeared to be positively correlated with habitat suitability scores. We suggest that Rock Partridge may be considered as a good candidate as an umbrella species, and in appropriate areas therefore be a useful tool for conservation of wildlife in Cilento and Vallo di Diano National Park, specifically, and potentially elsewhere within the species’ range
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
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
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