1,720,957 research outputs found
Assessment of placental metal levels in a South African cohort
No full textThe placenta plays an important role in mediating the effect of maternal metals exposure on fetal development, acting as both barrier and transporter. Term-placenta metals levels serve as an informative snapshot of maternal/fetal exposure during pregnancy and could be used to predict offspring short- and long-term health outcomes. Here, we measured term-placenta metal levels of 11 metals in 42 placentas from the Soweto First 1000 days cohort (S1000, Soweto-Johannesburg, SA).
We compared these placental metals concentrations to previously reported global cohort measurements to determine whether this cohort is at increased risk of exposure. Placental metals were tested for correlations to understand potential interactions between metals. Since these samples are from a birth cohort study, we also performed exploratory analyses to determine whether metals levels were associated with placenta and birth outcomes. Most S1000 placental metals levels were similar to other cohorts, however, cadmium (Cd) levels up to 50-fold lower, and essential elements nickel (Ni) and chromium (Cr) levels up to 6- and 16-fold lower, respectively. Cd, Se, and Ni were associated with placenta and birth outcomes. Studies are ongoing to examine underlying mechanisms and how these developmental differences affect long-term health
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
ASSESSMENT OF THE EFFECT OF GESTATIONAL DIABETES MELLITUS AND METALS EXPOSURE IN THE SOWETO FIRST 1000 DAYS COHORT ON PLACENTAL EPIGENETIC PROGRAMMING AND PLACENTAL & BIRTH OUTCOMES
Get PDFUsing the Soweto First 1000 Days cohort (S1000), we sought to understand the relationships among placental metal levels on birth & placental outcomes and characterize the impact of gestational diabetes mellitus (GDM) on placental programming in a previously unassessed South African population. We measured term-placenta levels of 11 metals in 42 placentas from the S1000. We compared these placental metals concentrations to previously reported global cohort measurements and tested for correlations to understand interactions between metals. Our primary aim was to understand the relationship between metals exposure and placental & birth outcomes. We found placental levels for Cr, Ni, Se, and Zn to be lower in the S1000 placentas, suggesting micronutrient deficiencies within this population. Cd, Se, and Ni were associated with placental and birth outcomes, highlighting low levels of essential elements can lead to negative health outcomes. For our secondary aim, we characterized the impact of GDM on genome-wide DNA methylation patterns in the placenta, with a focus on the perturbation of placental developmental genes. We conducted an epigenome-wide association study, comparing nonGDM placentas (n=21) to GDM placentas (n=21). GDM placentas exhibited a distinct methylation profile consisting of 12,210 differentially methylated CpGs (DMCs) that mapped to 3,875 genes. Epigenetically altered genes were enriched in Wnt and cadherin signaling pathways, both critical in placentation & embryogenesis. We also defined robust regional DNA methylation perturbation in GDM placentas at 11 placental development genes. These findings reveal extensive changes to the placental epigenome of GDM pregnancies and highlight perturbation enriched at important placental development genes. These molecular changes represent potential mechanisms of GDM-induced placental dysfunction that may serve as candidate biomarkers of placental injury and subsequent effects on maternal & fetal health. In conclusion, we demonstrated in a previously unassessed South African population that both maternal metabolic health (GDM) and environmental exposures (metals) can impact placental and fetal outcomes. What remains unknown are the mechanisms by which these exposures affect placental & fetal growth and development. This dissertation has shown that epigenetics is one way in which we can capture the effects of these exposures and infer potential mechanisms of action.Doctor of Philosoph
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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