1,720,964 research outputs found
Role of von Willebrand factor in the haemostasis
Full text linkvon Willebrand factor (VWF) is an adhesive and multimeric glycoprotein that found its historical origin in 1924, when the Finnish physician Erik von Willebrand first reported a family with a serious hereditary bleeding affecting consanguineous families. The proband was a five years old girl with severe bleeding since birth. Three sisters had died before the age of four, one living sister, aged three, also was severely affected. von Willebrand had thought that it was a disorder of platelet function or a vascular defect as a possible cause of the bleeding.
Since the original observations by Erik von Willebrand, the disease has been extensively studied and it was shown in the mid 1950s that impaired haemostasis was because of lack or an abnormality of a plasmatic factor - the von Willebrand factor – necessary for normal hemostasis
Prenatal diagnosis and preimplantation genetic diagnosis : novel technologies and state of the art of PGD in different regions of the world
No full textPrenatal diagnosis (PND) aims to provide accurate, rapid results as early in pregnancy as possible. Conventional PND involves sampling cells of foetal origin by chorionic villus sampling at 11-14th weeks of pregnancy or amniocentesis after 15th week. These are invasive procedures and have a small but significant rate of 0.5% to 1% for loss of pregnancy. An alternative to existing methods for conventional PND for couples at risk of transmitting a genetic disease to their child is preimplantation genetic diagnosis (PGD). PGD is a newly emerging form of a very early prenatal diagnosis. The technique combines assisted reproductive technology with molecular genetics and cytogenetics to allow the identification of abnormality in embryos prior to implantation. The diagnosis of genetic disease in human preimplantation embryos was pioneered in the late 1980s for testing of aneuploidy, single gene and X-linked disease, such as cystic fibrosis, haemophilia and chromosomal abnormalities. The PGD-related legal and ethical issues have been debated at many levels both nationally and internationally. The attitude towards PGD varies substantially not only in different parts of the world but also within the Europe, owing to scientific, cultural and religious differences. PGD has become widely practised throughout the world for various indications and can substantially decrease the eventual risks of passing a genetic undesired condition of the offspring. Nevertheless, its extension to some new and non-medical indications has raised ethical concerns, in particular its potential eugenic dimensio
A rare inherited coagulation disorder : combined homozygous factor VII and factor X deficiency
No full textThe combined presence in the homozygous state of more than one recessively transmitted coagulation defect may rarely occur in countries with a high rate of consanguinity. In an Iranian family consisting of two parents (second cousins) and two affected siblings, initial phenotypic analysis led to a diagnosis of mild FX deficiency (10–19% FX activity,
42–54% FX:Ag), and genotyping revealed a new homozygous missense mutation in the
corresponding gene (Ser3Cys). As both of the sibs had a severe bleeding history that was not compatible with mild deficiency of FX, further phenotypic analysis revealed the
additional presence of severe FVII deficiency (<1% FVII activity; 63–111% FVII:Ag) associated with the homozygous missense gene mutation Cys310Phe. In this kindred, lack of identification of the double coagulation defect might have led not only to incomplete understanding of the clinical phenotype but also to an incorrect prenatal diagnosis
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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