1,721,027 research outputs found
Genetic influence on age at first birth of female twins born in the UK, 1919-68
No full textUsing a sample of monozygotic (945, 42 per cent) and dizygotic (1,329, 58 per cent) twin pairs born 1919–68 in the UK, we applied innovative tobit models to investigate genetic and environmental influences on age at first birth (AFB). We found that a substantial part (40 per cent) of the variation in AFB is caused by latent family characteristics. Genetic dispositions (26 per cent) play a more important role than the shared environment of siblings (14 per cent), with the non-shared environment/measurement error having the strongest influence (60 per cent). Like previous studies, this study reveals marked changes in estimates over time, and supports the idea that environmental constraints (war or economic crisis) suppress and normative freedom (sexual revolution) promotes the activation of genetic predispositions that affect fertility. We show that the exclusion of censored information (i.e., on the childless) by previous studies biased their results
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
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
Social science genetics and fertility:Essays on the Interplay Between Genes, Social Environment and Human Fertility
Get PDFTo what extent do genes influence the age at which you have your first child and the number of children that you have? Does the social environment influence genetic effects on fertility? Do genes lead to spurious associations between life outcomes such as education and age at first birth? The social sciences have been slow to integrate a genetic approach to the study of fertility choice and behaviour, resulting in theories and findings that are largely socially deterministic. This dissertation investigates genetic and environmental influences on human fertility—as well as their interplay—using both twin data and molecular genetic data of more than 31,000 genotyped individuals from six countries.The central finding from this dissertation is that individual differences in fertility behaviour are associated with genetic differences: this implies ongoing natural selection in humans. However, it is also found that genetic variants associated with fertility can differ across countries and time. Taking the historical and geographic environment into account can increase the explanatory power of genes for fertility up to five times. A twin study shows that the association between education and the age at first birth is largely spurious due to family background effects—not genes. This casts doubt on the idea that the educational expansion in the second half of the 20th century is responsible for the strong fertility postponement all over Europe. Overall, the results demonstrate that an integrative research approach of social sciences and genetics generates important insights into human fertility
Social science genetics and fertility:Essays on the Interplay Between Genes, Social Environment and Human Fertility
Get PDFTo what extent do genes influence the age at which you have your first child and the number of children that you have? Does the social environment influence genetic effects on fertility? Do genes lead to spurious associations between life outcomes such as education and age at first birth? The social sciences have been slow to integrate a genetic approach to the study of fertility choice and behaviour, resulting in theories and findings that are largely socially deterministic. This dissertation investigates genetic and environmental influences on human fertility—as well as their interplay—using both twin data and molecular genetic data of more than 31,000 genotyped individuals from six countries.The central finding from this dissertation is that individual differences in fertility behaviour are associated with genetic differences: this implies ongoing natural selection in humans. However, it is also found that genetic variants associated with fertility can differ across countries and time. Taking the historical and geographic environment into account can increase the explanatory power of genes for fertility up to five times. A twin study shows that the association between education and the age at first birth is largely spurious due to family background effects—not genes. This casts doubt on the idea that the educational expansion in the second half of the 20th century is responsible for the strong fertility postponement all over Europe. Overall, the results demonstrate that an integrative research approach of social sciences and genetics generates important insights into human fertility
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