1,720,957 research outputs found
Running Over the Same Old Ground: Stegomastodon Never Roamed South America
No full textThe diversity of South American proboscideans during the Quaternary has been a subject of discussion for decades. The presence of Cuvieronius hyodon in South America is unquestioned and unanimous; however, the taxonomy of the known second South American proboscidean is still a controversy. Some authors argue that the South American species traditionally referred to Stegomastodon should instead be referred to a distinc genus, namely Notiomastodon, endemic to South America. Others authors, however, do not accept this attribution and continue to recognize the genus Stegomastodon as present in South America. In this study, we recognize several differences in the mandible, skull, dentition, and postcranial morphology of North American species of Stegomastodon and Notiomastodon, that further support the validity of Notiomastodon as a taxon separate from Stegomastodon. Indeed, a phylogenetic hypothesis of trilophodont bunodont proboscideans supports the separation between Stegomastodon and Notiomastodon, and the diversification of the common ancestor of these proboscideans may have occurred during the middle to late Miocene. No specimen with Stegomastodon diagnostic features is recognized in South America. The Stegomastodon records are restricted to the Pliocene-middle Pleistocene of North America, while Notiomastodon records are found only from the middle Pleistocene-early Holocene of South America. In this way, we recognize that Stegomastodon records are restricted to North America and that only Cuvieronius and Notiomastodon are recorded in South America
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 evolution of Palaeoloxodon skull structure:Disentangling phylogenetic, sexually dimorphic, ontogenetic, and allometric morphological signals
No full textThis paper presents a reappraisal of evolution in the extinct Pleistocene straight-tusked elephant Palaeoloxodon, based on cranial morphology. Particular emphasis is given to the parieto-occipital crest (POC), a specialised structure of the Palaeoloxodon skull. A key aim of this contribution is to discuss the systematic significance of the so-called “Stuttgart” and “namadicus” cranial morphs among Eurasian Palaeoloxodon. Materials examined and discussed mostly represent large-sized continental species from several Afro-Eurasian localities, but includes also the small-sized endemic elephant Palaeoloxodon cf. mnaidriensis from the late Middle-early Late Pleistocene of Sicily. In Africa, where the lineage originated, the morphological evolution of Palaeoloxodon concerned both skull and molariform teeth, which became strongly hypsodont and bore up to 19 lamellae. This dental morphology underwent little notable evolutionary change in Eurasian Palaeoloxodon, contrasting to the marked disparity in their cranial morphology, best elucidated by variations in the POC. Maturation of a strong POC in Palaeoloxodon antiquus, P. namadicus and P. cf. mnaidriensis (Puntali Cave, Sicily) during ontogeny shows a consistent pattern: incipient folding at the M1 stage; complete folding at the M2 stage; further downward migration of the POC towards the nasals at the M3 stage. The POC morphology and variation result from complex interactions of factors, which include, to varying degrees, ontogeny (juvenile vs adult), allometry (e.g. skull size and shape) and possible phylogenetic inertia. Some evidence of sexual dimorphism in POC development is observed in P. namadicus, P. naumanni, and possibly P. antiquus, this is a possible allometric effect which reflects on the markedly greater body size of males at full maturity compared to females. Skull shape and variability of the POC, as well as postcranial proportions, support the specific separation of P. namadicus and P. antiquus. However, the observed pattern of intrapopulational POC variability from German and Italian P. antiquus samples does not support a turnover of the two distinct Palaeoloxodon species in Europe during the Middle Pleistocene (MIS 11–MIS 7). The poorly known P. turkmenicus might represent a separate Middle Pleistocene Palaeoloxodon species from Central Asia more plesiomorphic than either P. antiquus or P. namadicus. P. naumanni from Japan possesses a combination of primitive and derived, autapomorphic characters, supporting its interpretation as an early offshoot during Eurasian Palaeoloxodon evolution.</p
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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