1,720,978 research outputs found
The tail of the two: a study of twin embryos in Darevskia lizards
No full textAbstract Monozygotic twinning, which produces genetically identical organisms, exemplifies the widespread ability of embryonic regulation. Although the incidence of twinning varies considerably, it is found in many taxons. Only a few cases of monozygotic twinning have been reported in lizards. Previously, we reported a single observation of an incompletely separated twin in a parthenogenetic Caucasian rock lizard, Darevskia armeniaca . To clarify whether twinning is particularly common in this lizard species, we studied eggs of this and two other species (one parthenogenetic and one bisexual) of this genus. Among 125 examined, we identified four pairs of twin embryos. Separated twins (three cases) or embryos with axial bifurcation (one case) were recorded exclusively in Darevskia armeniaca . These twin or bifurcated embryos were found in the clutches of three out of 15 studied gravid females of this species, and in four out of the 69 studied embryos. No anomalies were observed in 39 eggs of parthenogenetic D. dahli and 17 eggs of bisexual D. valentini . Statistical analysis confirmed significantly higher rates of anomalies in D. armeniaca . Twin embryos were smaller than singleton embryos but showed advanced limb and scale development despite delayed progress in certain traits compared to bisexual D. valentini . Twin embryos of D. armeniaca were larger and more developed than singleton embryos of the parthenogenetic D. dahli , highlighting species-specific developmental differences. We discuss that an excessive proportion of twinning in D. armeniaca is due to the complex genetic origin of this parthenogen and its adaptation to a less stable environment, forcing females to invest more energy in a single reproduction than two other species. Simultaneously, twinning develops in the largest eggs of D. armeniaca , which may be deposited by aged females and whose size exceeds the threshold that may be common for all studied closely related species
The first record of Dictis L. Koch, 1872 (Araneae, Scytodidae) in the Caucasus
Full text linkDictis L. Koch, 1875, is recorded in the Caucasus for the first time. Dictis strandi (Spassky, 1941), comb. nov. is transferred to Dictis from Scytodes Latreille, 1804 based on the examined female and two males raised to maturity from the egg sac. Collecting data and digital photos of live and preserved specimens are provided, along with detailed descriptions of both sexes, diagnostic illustrations, and observations on the natural history of Dictis strandi comb. nov. The endogyne is depicted for the first time
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
The first record of Hemineura wittmeri Badonnel, 1981 (Psocodea, Psocomorpha, Elipsocidae) from the Caucasus
No full textThe second psocid species of the genus Hemineura Tetens, 1891, namely H. wittmeri Badonnel, 1981, is recorded from the Caucasus region for the first time based on several female and male specimens collected in the Shida Kartli region of Georgia. Collecting data are given along with diagnostic illustrations of the preserved specimens
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
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