1,720,955 research outputs found
A tool for feeding and mating: the Swiss Army stylet of Gyratrix hermaphroditus (Rhabdocoela, Platyhelminthes)
No full textFree-living flatworms are famous for their intriguing copulatory strategies, yet microturbellarian reproductive biology remains poorly characterised. Through direct and histological observations, we here elucidate the copulation mechanism within the cosmopolitan rhabdocoel species complex Gyratrix hermaphroditus Ehrenberg, 1831 (Polycystididae, Kalyptorhynchia). The sclerotized reproductive organs of these animals were visualized through Differential Interference Microscopy and Scanning Electron Microscopy. Mating behaviour is shown to constitute a sequence of events, including precopulatory ‘sniffing’ and ‘rolling’, followed by simultaneous insertion of the stylet sheath in the copulatory bursa of the partner and stylet ejection. Respective durations of these events were measured. As the copulatory organ is also used in foraging, we also report on the feeding mechanism of these animals: the stylet is used to puncture the prey’s body wall and the contents of the prostate vesicle are ejected, after which the worm uses it pharynx to feed on its prey’s body fluids. We suggest that the twofold role of the male copulatory organ may confine the evolutionary plasticity of this character trait, possibly explaining the morphological stasis in G. hermaphroditus
A tool for feeding and mating: The Swiss Army stylet of Gyratrix hermaphroditus
No full textFree-living flatworms are famous for their intriguing copulatory strategies, yet microturbellarian reproductive biology remains poorly characterised. Through direct and histological observations, we further elaborate on the copulation mechanism within the rhabdocoel species complex Gyratrix hermaphroditus (Polycystididae, Kalyptorhynchia). Mating behavior is shown to involve a sequence of events, including precopulatory ‘sniffing’ and ‘rolling’, followed by simultaneous insertion of the stylet sheath in the bursa of the partner and stylet ejection. Respective durations of these events are measured and reported. As parts of the male system are also used in foraging, we also report on the feeding mechanism of these animals: the stylet is used to puncture the prey’s body wall, and the contents of the prostate vesicle are ejected, after which the worm uses its pharynx to feed on its prey’s body contents. We suspect that negative genetic correlations due to the twofold role of the male copulatory organ may constrain the evolution of this character and possibly explains the relative morphological stasis for this trait in G. hermaphroditus.We wish to thank Mrs Natascha Steffanie for preparing the histological sections of Gyratrix hermaphroditus and Mrs Ria Vanderspikken for administrative support
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
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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