1,721,144 research outputs found
Are shoot features of actual diagnostic value in European bladderworts (Utricularia L., Lentibulariaceae)?
No full textIn central Europe, seven native species of Utricularia occur, mainly distinguished by flower features. They
can be subdivided in three aggregates according to shoot morphology: (1) Utricularia intermedia aggr.,
also comprising Utricularia ochroleuca and Utricularia stygia, (2) Utricularia vulgaris aggr., also comprising
Utricularia australis and (3) Utricularia minor aggr., also comprising Utricularia bremii. We tested some
shoot features as identification tools and investigated quadrifid digestive glands in all the studied species,
using geometric morphometrics. For U. intermedia aggr., in most cases, the tooth number per ultimate
leaf segment may be diagnostic. The three species of this aggregate overlap in terms of gland shape, but
averaging measurements by traps and individuals, a decrease of overlapping among species was found.
The shape and the centroid size of quadrifid glands in U. minor aggr. is unsuitable for discriminating species.
Concerning U. vulgaris aggr., U. vulgaris bears a higher ratio of setula length to tooth length than U. australis
(which is more toothed). This feature may help to distinguish species, but conflicting results were found in
one studied population. The relevance of quadrifid gland features as identification tool and the puzzling
systematic circumscriptions of the target species are discussed
Notes on the typification of the names Utricularia bremii Heer and U. intermedia Dreves & Hayne (Lentibulariaceae)
No full textIn the framework of a systematic revision of Central European Utricularia L. (Astuti & Peruzzi 2018), we came across a first-step typification (Meister 1900) concerning the name Utricularia bremii Heer in Koelliker (1839: 142), and a name yet untypified, i.e. U. intermedia Dreves & Hayne (1798: 104). A second-step typification and a lectotypification are designated here, respectively.</jats:p
Traditional cytotaxonomic studies: can they still provide a solid basis in plant systematics?
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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
Different chromosome numbers, but slight morphological differentiation and genetic admixture among populations of Pulmonaria hirta complex
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