1,721,239 research outputs found
Modelling normal returns in event studies: a model-selection approach and pilot study
No full textThe choice of model of normal returns in event studies has been widely discussed in the literature. While researchers frequently continue to use an array of alternatives, there is currently some tendency to favour cruder but simpler mean- or market-adjusted returns models. This paper presents a general-to-specific model selection framework for testing the data admissibility of the principal models in current use. Results from a pilot study indicate a strong preliminary preference in favour of the regression-based models, with the market model generally outperforming the capital asset pricing model
Will climate change alter parasite development?
No full textThe effect of climate change has already been seen in many ecological systems, but incorporating studies of parasites is vital to fully understand how ecological communities as a whole will respond. We used a meta-analytic approach to assess the role of climatic perturbation on parasite development, abundance and fecundity. Development increased with a temperature increase, but decreased as humidity increased under constant temperature. Abundance also increased, yet fecundity decreased with temperature changes. Our results demonstrate that these aspects of parasite fitness have a complex relationship with the climate, suggesting that future responses to global climate change will be difficult to predic
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
The description of Gyrodactylus corleonis sp.n. and G. neretum sp.n. (Platyhelminthes: Monogenea) with comments on other gyrodactylids parasitising pipefish (Pisces: Syngnathidae).
No full textThe current work describes two new species of Gyrodactylus von Nordmann, 1832 collected from pipefish Syngnathus
scovelli (Evermann et Kendall) and Syngnathus typhle L. during two separate gyrodactylosis episodes on fish held in a public
aquarium located in northern Italy. The gyrodactylids collected from the skin, fins and gills of pipefish were subjected to a morphological
analysis of the attachment hooks and the morphometric data were compared to the four species of Gyrodactylus previously
described from syngnathid hosts, namely G. eyipayipi Vaughan, Christison, Hansen et Shinn, 2010, G. pisculentus Williams, Kritsky,
Dunnigan, Lash et Klein, 2008, G. shorti Holliman, 1963 and G. syngnathi Appleby, 1996. Principal components analysis (PCA) of
the morphological data indicated six clusters; two discrete groups among the specimens taken from the pipefish held in the Italian
aquarium and four further groups representing G. eyipayipi, G. pisculentus, G. shorti and G. syngnathi. Molecular sequences of the
ribosomal internal transcribed spacers (ITS1 and ITS2) and the 5.8S gene for the new species considered here were then compared
with those available for other species in GenBank. The comparison did not reveal any identical match, supporting the morphological
analysis that Gyrodactylus corleonis sp. n. from S. typhle and Gyrodactylus neretum sp. n. from S. scovelli represent distinct species.
Both G. corleonis and G. neretum possess robust hamuli, marginal hook blades that curve smoothly from their sickle base to a point
beyond the toe and, ventral bars with a broad median portion and a reduced membrane. Gyrodactylus corleonis, however, can be
distinguished on the basis of its heart-shaped ventral bar; G. neretum has a 1:2 hamulus point:shaft ratio and a rectangular-shaped
ventral bar. A redescription of the haptoral hard parts of the four species previously recorded on pipefish is also presented
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