1,720,977 research outputs found
Abnormal development of paired enigmatic structures in the derived dicynodont Lystrosaurus murrayi (Therapsida, Anomodontia).
No full textDerived dicynodonts, including Lystrosaurus murrayi, have edentulous lower jaws. As an interesting
exception to this conventional wisdom, a well-preserved specimen of L. murrayi (MGGC-
8850/1RE13 F) has abnormal, paired mandibular structures similar in overall morphology to dental
teeth. The specimen pertains to the historical collections of the Museo G. Capellini (Bologna, Italy)
and was collected in 1929 by M. Gortani during prospecting activities near Harrismith, South Africa.
The specimen is articulated and includes a nearly complete skull, the first eight vertebrae and the
proximal end of the right scapula. Reconstruction based on a Dual-Beam CT revealed unusual,
paired structures similar to mandibular teeth, encased within the lower jaw, lingual to maxillary tusks.
Different interpretations are possible for the abnormal mandibular structures in MGGC-8850/1RE13
F: 1) the dental lamina in the lower jaw, which would normally degenerate in derived dicynodonts,
remained active and potentiated the odontogenesis; 2) the dental lamina was potent in the lower jaw
throughout the ontogeny across dicynodonts but activated differentially; or 3) the mandibular
patterning in our specimen was dorsalized, which resulted in an ectopic formation of upper jaw
dentition in the lower jaws. Supranumerary or ectopic teeth are a commonly screened phenotype in
modern mammalian models. Such variation distributes in a continuum – rarely does an edentulous
jaw develop fully functional teeth that are present in outgroups. The absence of mandibular dentition
in other specimens of L. murrayi and in most other bidentalian dicynodonts suggests that MGGC-
8850/1RE13 F represents a rare developmental abnormality or a case of atavism
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
Do cladistic and morphometric data capture common patterns of morphological disparity?
Full text linkThe distinctly non-random diversity of organismal form manifests itself in discrete clusters of taxa that share a common body plan. As a result, analyses of disparity require a scalable comparative framework. The difficulties of applying geometric morphometrics to disparity analyses of groups with vastly divergent body plans are overcome partly by the use of cladistic characters. Character-based disparity analyses have become increasingly popular, but it is not clear how they are affected by character coding strategies or revisions of primary homology statements. Indeed, whether cladistic and morphometric data capture similar patterns of morphological variation remains a moot point. To address this issue, we employ both cladistic and geometric morphometric data in an exploratory study of disparity focussing on caecilian amphibians. Our results show no impact on relative intertaxon distances when different coding strategies for cladistic characters were used or when revised concepts of homology were considered. In all instances, we found no statistically significant difference between pairwise Euclidean and Procrustes distances, although the strength of the correlation among distance matrices varied. This suggests that cladistic and geometric morphometric data appear to summarize morphological variation in comparable ways. Our results support the use of cladistic data for characterizing organismal disparity
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
First volumetric body mass estimate and a new in vivo 3D reconstruction of the oldest Karoo pareiasaur Bradysaurus baini, and body size evolution in Pareiasauria
No full textPareiasaurs were among the world’s first large terrestrial tetrapods, first appearing during the Guadalupian Epoch, and were later widespread across Pangea during the Lopingian where they formed a significant part of the large herbivore guild. The Bradysauria of the Lower Beaufort Group of the Karoo Basin of South Africa are among the oldest pareiasaurs, yet little is known of their palaeobiology. Here, we present the first volumetric body mass estimate and a new in vivo reconstruction of the earliest Karoo pareiasaur, and the phylogenetically basal-most pareiasaur, Bradysaurus baini, based on two almost complete adult mounted skeletons. Using 3D photogrammetric models of the two skeletons, we calculated a possible body mass range for B. baini by applying different densities for living tissue to reconstructions of differing soft tissue mass. Considering the larger adult Bradysaurus specimen, our volumetric body masses range from a minimum of 851.4 kg to a maximum of 1,276.5 kg, with an overall mean body mass of 1,022 kg, approximately the body weight of a large domestic cow. The study provides a more precise estimate of body mass in early members of Pareiasauridae, and we suggest that they were somewhat smaller than some late Permian taxa such as Scutosaurus karpinskii
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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