1,720,972 research outputs found
Telomere Length and Distribution in Three Developmental Stages
Get PDFTelomeres are specialised nucleoprotein structures present at the ends of each chromatid that function to maintain genome stability. It is well established that a gradual decline in telomere length is associated with the process of cellular ageing, and thereby to the pathobiology of age-related diseases. In addition, the localisation of the telomere at the nuclear periphery plays an important role in the spatio-temporal organisation of the genome and in ensuring faithful segregation of chromosomes during meiosis. The aims of this thesis were to investigate telomere localisation in the nucleus, and telomere length in three hitherto early stages of development, gametogenesis, preimplantation embryogenesis and the neonatal period. Specifically:
1. To test the hypothesis that telomeres localised at the nuclear periphery in sperm cells and that this organisation was altered in sub-fertile men
2. To optimise a means of assessing average telomere length using DNA from small sample sizes and using whole genome amplified DNA from single cells
3. To investigate the role of telomere length in reproductive ageing and aneuploidy generation in women by testing the hypothesis that telomere length is significantly shorter in the first polar bodies and cleavage stage embryos of older women
4. To test the hypothesis that “preterm at term” babies (i.e. premature babies assessed at the time of their due date) displayed genetic signs of premature ageing (as manifested by significantly shorter telomeres than their term born counterparts) alongside the already established clinical signs (characterised by hypertension, diabetes and altered body fat distribution)
Results confirmed the peripheral distribution of telomeres in the sperm heads of normally fertile males (using both 2D and 3D imaging) plus the novel finding that telomere distribution patterns are altered in the sperm heads of infertile males. Secondly, a reliable means of measuring telomere length was optimised in order to assess average telomere length using DNA from small sample volumes (down to single cells). Using this technology, average telomere length analysis in polar bodies and embryos found no evidence to support the hypothesis that telomere length is associated with either advanced maternal age or aneuploidy generation. Similarly, results suggest that telomere length is not significantly shorter in “preterm at term” infants compared to term born controls, thus providing no evidence that telomere attrition is involved in the pathobiology of the ‘aged phenotype’ observed in preterm infants. Taken together, results from this thesis provide some novel insights into the function of these highly important features of the genome, but also highlight that a great deal remains to be uncovered in the complex molecular mechanisms that contribute to the regulation of telomere length and nuclear distribution
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
The influence of nutrition on the preterm phenotype at term
No full textEThOS - Electronic Theses Online ServiceGBUnited Kingdo
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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