1,720,956 research outputs found
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
Outcrossing rates in a rare “ornithophilous” aloe are correlated with bee visitation
No full textPollinator taxa may vary in their contribution to plant outcrossing rates and hence differ in their influence on plant fitness. In plants that have ornithophilous floral traits (large, deep-tubed orange-red flowers with dilute nectar), it is expected that birds should be the most effective agents of outcrossing. However, bees often pollinate plants with ornithophilous floral traits and may contribute to their outcrossing. To assess the contribution of bees to outcrossing rates and inbreeding in the rare self-compatible treelet Aloe thraskii, we compared outcrossing rates (t) and adult inbreeding coefficients (F), in bird-excluded and open-pollinated plants. We then tested whether outcrossing rates, and inbreeding depression (δ) estimated using Ritland’s genetic marker-based approach, varied according to bee and bird visitation rates, plant height, flowering population size, population density, and isolation distance across eight populations. Outcrossing rates did not differ between progeny from open-pollinated and bird-excluded inflorescences. Outcrossing rates increased with bee visitation, but not bird visitation. Adult inbreeding coefficients were low (F = 0–0.1), and inbreeding depression estimates were high (δ = 0.59–1). Estimates of inbreeding depression did not vary according to population aggregation. These results highlight the contribution to outcrossing that insect pollinators can make to outcrossing rates of rare plant species that are seemingly adapted for bird pollination
High levels of fecundity in small and isolated populations of a self-compatible Aloe pollinated by opportunistic birds and bees
No full textPlant species that are effective colonisers of transient habitats are expected to have a capacity for uniparental reproduction and show flexibility in pollination systems. Such traits may enable populations to be established from a small number of founding individuals without these populations succumbing to reductions in fecundity arising from pollinator limitation. We tested these predictions for Aloe thraskii (Xanthorrhoeaceae), a succulent treelet that colonises shifting coastal dunes and has both bird and bee pollinators. We performed hand-pollination experiments, and selectively excluded bird visitors to determine differences in pollinator effectiveness. We measured pollinator visitation rates and fecundity in populations varying in their size, density and isolation distance. Controlled hand-pollinations revealed that unlike most other Aloe species, A. thraskii is self-compatible and thus capable of uniparental reproduction. The species does however depend on pollinators and is visited by various bird species as well as by bees. Fruit and seed set are not affected by selective exclusion of birds, thus indicating that bees are effective pollinators. Bird visitation rates increased with increasing plant height and population size, while bee visitation rates increased with increasing population size and density. We found that seed set per flower was lower in large populations than in small populations. These results suggest that establishment of populations of A. thraskii from a small number of individuals is unlikely to be limited by the fecundity of individual plants
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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