1,720,994 research outputs found
A surprising link with unexplained infertility: a possible Covid-19 paradox?
No full textUnexplained infertility represents about 22–28 percent of infertility causes.The diagnosis is based on the exclusion of common causes
using standard fertility investigation. Over the years, the causes of unexplained infertility or subfertility have been identified in pre-existing associated pathologies, such as alterations of the immune system, thyroid dysfunctions, and coagulopathies.Studies regarding the influence of psychological factors on the development of infertility highlighted that spontaneous pregnancies following adoption or the decision to remain childless are absolute exceptions. The link between stress and infertility in humans is still unclear. For many women, the effect of infertility and the subsequent medical therapy represents a considerable emotional stress
Further studies on the role of glycosylation in thyroxine-binding globulin (TBG) secretion by human hepatoma (Hep G2) cells
No full textthyroxine uptake by human hepatoma cells from serum of patients submitted to long-term thyroxine suppressive therapy
No full textPregnancy-related immune tolerance. Maternal-fetal interactions
No full textThe conceptus may be considered as a sort of semi-allogenic graft for the maternal organism, since it shares a half of genomic complement with the father. Nevertheless, its rejection does not take place physiologically during a pregnancy. The mechanisms resulting in the maternal immune tolerance versus the conceptus are not yet completely clarified. Such mechanisms are probably multiple and interacting with each other. In animal and in vitro studies provide evidence suggesting that the following factors are important in producing the maternal immune tolerance: the anatomical position of the fetus; the absence of expression of the class I and II Major Histocompatibility Complex (MHC) molecules in trophoblast tissues; the activity of blocking antibodies; a modification of the immune response; the fetal-placental production of immunosuppressive hormones and substances. Amongst pregnancy-related changes in the immune response, a reduced Natural Killer (NK) cell activity and an increased synthesis of Th2 cytokines (which inhibit the cell-mediated immunity) with an altered Th1/Th2 balance appear to be remarkably important. With regard to fetal-placental hormones, progesterone seems to exert an important immunosuppressive influence mediated by the protein named "Progesterone Induced Blocking Factor" (PIBF). Nevertheless, the real contribution of each of the above mentioned mechanisms still remains to be elucidated in humans
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
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
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