1,720,982 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Reproductive inhibition in female common and highveld mole-rats: neuroanatomical and neuroendocrine perspectives
No full textThesis (PhD)--University of Pretoria, 2005.The social reproductive inhibition evident in female common (Cryptomys hottentotus hottentotus) and highveld (Cryptomys hottentotus pretoriae) mole-rats was investigated, focussing on intra- and inter-subspecies differences in gonadotropin¬releasing hormone (GnRH) neuroanatomy and neuroendocrinology and potential mechanisms mediating social infertility through the suppression of luteinizing hormone (LH) and/or GnRH synthesis or release. The molecular structure of the GnRH peptide present in highveld mole-rat tissue was determined. Messenger ribonucleic acid (mRNA) coding for GnRH was isolated from hypothalamic tissue of a female highveld mole-rat. The nucleotide sequence of the transcribed complimentary deoxyribonucleic acid (cDNA) predicts amino acid sequences that indicate a potential polymorphism in the mature peptide. These sequences differ from classic 'mammalian' GnRH by either one or two amino acid positions. One form of mole-rat GnRH is identical to the unique GnRH expressed by guinea pigs, while the second form differs from guinea pig GnRH in one amino acid position. These results indicate that classic 'mammalian' GnRH is not the chief structural form of GnRH in the mole-rat. In both the common and highveld mole-rat, GnRH structures were loosely distributed along the septo-preoptico-infundibular pathway. Highveld mole-rats consistently had more GnRH cell bodies and higher levels of the peptide than common mole-rats. The subspecies also differed with regards to the relative distribution of GnRH cell bodies in the preoptic area and the medio-basal hypothalamus. Reproductive status and season did not influence GnRH neuroanatomy (numbers and morphology of cell bodies, distribution of GnRH structures and density of GnRH staining in the median eminence) or endogenous brain GnRH content in male or female common mole-rats. Likewise reproductive and non-reproductive male highveld mole-rats did not differ with regards to the GnRH neuroanatomical and neuroendocrinological parameters investigated. Dominant and subordinate female highveld mole-rats had similar numbers of GnRH cell bodies, and did not differ with regards to the distribution of GnRH structures. Brain GnRH levels was however significantly lower in reproductive females compared to non-reproductive females. Similarly, GnRH staining in the median eminence was significantly less intense in reproductive compared to non-reproductive females, indicating reduced release in the latter. Excess peptide most likely accumulates in the nerve terminals and the cell bodies. Endogenous opioid peptides (EOPs) are tentatively considered to playa role in the socially-induced infertility in non-reproductive female highveld mole-rats. Intact reproductive females and intact and ovariectmized non-reproductive females were treated with the opioid antagonist naloxone, alone and in different combinations with exogenous GnRH, to establish the role of EOPs and gonadal hormones in the reduced GnRH release evident in subordinate female highveld mole-rats. Naloxone treatment failed to alter plasma LH levels in any of the intact groups, while ovariectomized non-reproductive females showed a significant response. The pituitary response to a GnRH challenge was not influenced by either a single naloxone administration or longer term naloxone-priming regimens. In the absence of the negative feedback effects of gonadal steroids following ovariectomy, non¬reproductive females showed GnRH-chalienged plasma LH levels similar to that seen in intact reproductive females, both being significantly higher compared to intact non-reproductive females. Steroid-dependent mechanisms altering GnRH secretion and/or pituitary sensitivity to the endogenous peptide may therefore playa role in the social reproductive regulation displayed by the highveld mole-rat. EOPs may be indirectly involved in steroid negative feedback suppression of GnRH. In conclusion, the GnRH neuroanatomy and neuroendocrinology of female common mole-rats provide no evidence for a physiological component to the behavioural reproductive restraint in subordinate females due to incest avoidance. Non¬reproductive female highveld mole-rats are, however, temporarily infertile due to pituitary insensitivity to GnRH coupled with suppressed hypothalamic GnRH release potentially mediated by steroid-dependent mechanisms.Zoology and Entomologyunrestricte
The reproductive biology of the solitary Cape mole-rat, Georychus capensis and the social Natal mole-rat, Cryptomys hottentotus natalensis (Rodentia : Bathyergidae)
Get PDFThesis (PhD)--University of Pretoria, 2008.The seasonality of wild caught Cape mole-rats was investigated, focusing on endocrine, neuroendocrine and neuroanatomical parameters. The Cape mole-rat reproduces only during the winter rainfall period of the western Cape Province. Interestingly, the gonadal steroid hormones do not show any significant seasonal patterns in either males or females. In addition, the pituitary does not exhibit a reduced sensitivity to GnRH stimulation during the non-breeding season in either sex. Moreover, in the brain the distribution, number and size of GnRH perikarya do not differ with respect to season. Therefore, although only producing young during a specific period of the year, the Cape mole-rat does not appear to be physiologically repressed from reproducing throughout the year. The results of this study imply that the Cape mole-rat is an opportunistic breeder that is reproductively quiescent during the dry season as a consequence of ecological factors such as lack of favourable burrowing conditions and that when opportunities avail themselves following aseasonal rainfall, reproduction may occur. The seasonality and socially induced infertility of the Natal mole-rat was examined via endocrine, neuroendocrine and neuroanatomical investigations. In contrast with the phylogenetically closely related common mole-rat and highveld mole-rat, the Natal mole-rat does not appear to breed seasonally. Post-mortem examination of animals collected revealed pregnant reproductive females throughout the year. A similar scenario is reflected in gonadal steroid concentrations, with no major seasonal differences observed in either males or females. Likewise, pituitary sensitivity to GnRH does not change over season in males or females, and all neuroanatomical parameters investigated remained stable over season in both males and females. Natal mole-rats captured for this study occur in an area with a high annual rainfall, (almost double that of the common mole-rat habitat and one and a half times that of the highveld mole-rat) and the relatively higher rainfall and hence soil moisture content may provide the Natal mole-rat with increased foraging time a result of increased periods over which the soil is optimal for burrowing. Socially induced infertility in the Natal mole-rat appears to be enforced behaviourally as a result of active incest avoidance. The circulating testosterone concentrations were not significantly different in reproductive and non-reproductive males, and likewise oestrogen concentrations did not differ between reproductive and non-reproductive females. Progesterone concentrations were very low in subordinate females, but markedly higher in reproductive females. This is not surprising since the Natal mole-rat is an induced ovulator, thus coitus is required to induce the LH surge that stimulates ovulation. The sensitivity of the pituitary to a GnRH challenge did not differ between reproductive and non-reproductive animals from either sex. No neuroanatomical differences were observed between reproductive and non-reproductive animals of either sex, however, non-reproductive males and females had significantly higher amounts of GnRH in the median eminence, implying that GnRH is synthesized and transported to the median eminence but not released in the portal system to the anterior pituitary. These findings suggest that non-reproductive animals of both sexes are not sterile, but merely sexually quiescent. CopyrightZoology and Entomologyunrestricte
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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