1,721,037 research outputs found
High variability in the expression of circadian rhythms in a cave beetle population
No full textCave-dwelling organisms belong to widely different evolutionary lineages but they show parallel or convergent evolution in several morphological and physiological traits such as elongated appendages, lower metabolism, specialized sensory systems, loss of eye and pigmentation. Circadian rhythms in locomotor activity have already been documented in hypogean insects but ultradian rhythmicity in cave-dwelling organisms has been reported only by recent authors. We selected Laemostenus latialis as a good candidate to investigate the biological clock functioning in a species thought to be at its beginning of the process of cave evolution in the darkness. We based our analysis on inferential methods used here to obtain the quantitative resolution of the rhythm features. An automatic electronic device was developed to this purpose so to continuously monitoring the general locomotor activity of individual cave-dwelling beetles. We found significant locomotor rhythms to be present and that Laemostenus maintained a 24-h circadian rhythm but with a different amplitude. We observed two different and opposite behavioural patterns: the "Rhythmic group" showed a typical circadian rhythmicity of surface-dwelling animals with a surprisingly and extremely stable circadian period and with a restricted variance and a high amplitude. Differently, within the "arrhythmic group" we have observed an evanescent circadian period with high variability in tau, a larger variance and a lower amplitude. DFT spectral analysis showed the presence of ultradian rhythms with several significant peaks in the range 1-10 h and a main peak at 12 h, similar to those found in mysid crustaceans, cockroaches and mice. Ultradian rhythm looked independent from the circadian one and we did not observe any regularity. Further experimental studies are still needed to track the variation of this trait along the process of adaptation to cave life, particularly in closely related populations and species of troglophilic animals. © 2014 © 2014 Taylor & Francis
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
Phylogeography of Helleria brevicornis Ebner 1868 (Crustacea, Oniscidea): old and recent differentiations of an ancient lineage.
No full textHelleria brevicornis has a disjunct, peri-Tyrrhenian distribution that mirrors that. of several organisms, for which geographic vicariance is invoked, due to the geological events started with the Oligocene split of the Sardo-Corsican microplate from the Pyrenees, and successive separation between Sardinia and Corsica. Molecular phylogenetic analyses demonstrated that such a biogeographic model does not apply to Helleria. The original split of the Sardinian and Corsican lineages originated in the Early Pliocene. Further diversification occurred later. The colonization of the Tuscan archipelago, French, and Italian mainland occurred most recently, but a possible time dependency bias suggests that such colonization was driven by human-transport. (C) 2009 Elsevier Inc. All rights reserved
European Society for Evolutionary Biology 2nd Congress Roma, Italy - September 3-7, 1989
No full textDispelling 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
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