1,720,998 research outputs found
Overcoming Deep Roots, Fast Rates, and Short Internodes to Resolve the Ancient Rapid Radiation of Eupolypod II Ferns
No full textA revised family-level classification for eupolypod II ferns (Polypodiidae: Polypodiales)
No full text) with a conserved type
No full textWith the advent of molecular phylogenetics, Perrie & al. (in Austral. Syst. Bot. 28: 256–264. 2015), Schneider & al. (in Perspect. Pl. Ecol. Evol. Syst. 18: 70–78. 2016), Shang & al. (in Molec. Phylogen. Evol. 127: 449–458. 2018), Schwartsburd & al. (in Molec. Phylogen. Evol. 150: 106881. 2020), and Wang & al. (in Taxonomy 1: 256–265. 2021) demonstrated the paraphyly (or polyphyly) of Dennstaedtia, with Microlepia and small segregates (Leptolepia Prantl, Oenotrichia Copel.) nested within it. These papers also proposed that sorus position in Dennstaedtiaceae is a homoplastic character, evolving from marginal to abaxial (sub-marginal for the authors) at least five times in the family, and reversing again to marginal at least two times (Schwartsburd & al., l.c.: fig. 5C; Wang & al., l.c.).Fil: Triana Moreno, Luz Amparo. Universidad de Caldas. Facultad de Ciencias Exactas y Naturales; ColombiaFil: Schwartsburd, Pedro Bond. Universidade Federal de Viçosa; BrasilFil: Yañez, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Pena, Nelson Túlio L.. Universidade Federal de Viçosa; BrasilFil: Kuo, Li-Yaung. National Tsing Hua University; ChinaFil: Rothfels, Carl. University of California. Department of Integrative Biology; Estados UnidosFil: Sundue, Michael. University of Vermont; Estados Unido
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
rbcL and matK earn two thumbs up as the core DNA barcode for ferns.
Full text linkBackgroundDNA barcoding will revolutionize our understanding of fern ecology, most especially because the accurate identification of the independent but cryptic gametophyte phase of the fern's life history--an endeavor previously impossible--will finally be feasible. In this study, we assess the discriminatory power of the core plant DNA barcode (rbcL and matK), as well as alternatively proposed fern barcodes (trnH-psbA and trnL-F), across all major fern lineages. We also present plastid barcode data for two genera in the hyperdiverse polypod clade--Deparia (Woodsiaceae) and the Cheilanthes marginata group (currently being segregated as a new genus of Pteridaceae)--to further evaluate the resolving power of these loci.Principal findingsOur results clearly demonstrate the value of matK data, previously unavailable in ferns because of difficulties in amplification due to a major rearrangement of the plastid genome. With its high sequence variation, matK complements rbcL to provide a two-locus barcode with strong resolving power. With sequence variation comparable to matK, trnL-F appears to be a suitable alternative barcode region in ferns, and perhaps should be added to the core barcode region if universal primer development for matK fails. In contrast, trnH-psbA shows dramatically reduced sequence variation for the majority of ferns. This is likely due to the translocation of this segment of the plastid genome into the inverted repeat regions, which are known to have a highly constrained substitution rate.ConclusionsOur study provides the first endorsement of the two-locus barcode (rbcL+matK) in ferns, and favors trnL-F over trnH-psbA as a potential back-up locus. Future work should focus on gathering more fern matK sequence data to facilitate universal primer development
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