1,721,344 research outputs found
Autoimmune diseases of the liver and biliary tract and overlap syndromes in childhood
No full textAutoimmune liver diseases in childhood includes Autoimmune Hepatitis (AIH) and Primary (Autoimmune) Sclerosing Cholangitis (P(A)SC). Both diseases are characterized by a chronic, immune-mediated liver inflammation involving mainly hepatocytes in AIH and bile ducts in PSC. Both diseases, if untreated, lead to liver cirrhosis. AIH could be classified, according to the autoantibodies pattern, into two subtypes: AIH type 1 presents at any age as a chronic liver disease with recurrent flares occasionally leading to liver cirrhosis and liver failure. Characterizing autoantibodies are anti-nuclear (ANA) and anti-smooth muscle (SMA), usually at high titer (>1:100). These autoantibodies are not specific and probably do not play a pathogenic role. AIH type 2 shows a peak of incidence in younger children, however with a fluctuating course. The onset is often as an acute liver failure. Anti-liver kidney microsome autoantibodies type 1 (LKM1) and/or anti-liver cytosol autoantibody (LC1) are typically found in AIH type 2 and these autoantibodies are accounted to have a potential pathogenic role. Diagnosis of AIH is supported by the histological finding of interface hepatitis with massive portal infiltration of mononuclear cells and plasmocytes. Inflammatory bile duct lesions are not unusual and may suggest features of ''overlap'' with P(A)SC. A diagnostic scoring system has been developed mainly for scientific purposes, but his diagnostic role in pediatric age is debated. Conventional treatment with steroids and azathioprine is the milestone of therapy and it is proved effective. Treatment withdrawal however should be attempted only after several years. Cyclosporin A is the alternative drug currently used for AIH and it is effective as steroids. P(A)SC exhibit a peak of incidence in the older child, typically in pre-pubertal age with a slight predominance of male gender. Small bile ducts are always concerned and the histological picture shows either acute cholangitis (bile duct infiltration and destruction) and/or lesions suggesting chronic cholangitis as well (bile duct paucity and/or proliferation, periductal sclerosis). Small bile ducts damage may be associated, at onset or in the following years, with lesions of larger bile ducts with duct wall irregularities, strictures, dilations, and beading resulting in the characteristic ''bead-on-a-string'' appearance. The ''small duct'' (autoimmune) sclerosing cholangitis is also called autoimmune cholangitis. PSC is strictly associated to a particular form of inflammatory bowel disease (IBD) which shows features not typical of ulcerative colitis neither of Crohn's disease. Symptoms related to IBD often are present at onset (abdominal pain, weight loss, bloody stools) but the liver disease is frequently asymptomatic and it may be discovered fortuitously. Treatment of PSC is particularly challenging. In case of ''small duct'' SC or in case of evidence active inflammation on liver biopsy, immunosuppressive treatment is probably useful while in case of large bile ducts non inflammatory sclerosis, immunosuppression is probably uneffective. Ursodeoxycholic acid, however, may leads to an improvement of liver biochemistry even if there's no evidence that it may alter the course of disease. Thus, liver transplantation, is often necessary in the long term follow-up, even with a risk of disease recurrence. In adjunction to these two main disorders, many patients show an''overlap'' disease with features of both AIH and PSC. In such disorders the immune-mediated damage concerns both the hepatocyte and the cholangiocyte with a continuous clinical spectrum from AIH with minimal bile ducts lesions and PSC with portal inflammation and active inflammatory liver damag
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
A multicriteria approach to support the design of complex systems
No full textNumerous design problems exist when the product is so complex that it has to be decomposed and given to specialists from different disciplines. Multidisciplinary interaction is difficult and therefore specific methodologies are proposed for the design of systems and for the coordination of the involved organizational groups. The concept of interaction between disciplines is related to the original work context, the design coordination, but can be extended to all situations in which different sectors are involved, in technical, administrative or management contexts. A collaboration between the Thales Alenia Space Italia enterprise and the university made it possible to define the problem of supporting the design of complex systems, in relation to the firm's design processes, and to test some innovative approaches. One of these approaches integrates methods of Problem structuring and Multicriteria analysis. The results, in relation to a specific space-mission case study, are presented and analyse
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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