1,721,093 research outputs found
Hepatitis C virus infection: 10 years after the discovery of the virus
No full textThe hepatitis C virus (HCV) causes an acute but very often chronic liver disease. An estimated 3% of the world population is chronically infected with HCV, Chronic hepatitis C is the major cause of cirrhosis and hepatocellular carcinoma (HCC), which most often lead to liver transplantation. HCV is a single-stranded enveloped RNA virus; it belongs to the flaviviridae family. The virus has been classified into six genotypes, some of which are distributed worldwide, others of which are confined to more restricted areas. The genotype is an independent predictor of response to antiviral treatment. Blood transfusion was a major risk factor for acquiring HCV infection before donor screening for surrogate marker testing for non-A, non-B (NANB) hepatitis began in the mid-1980s, followed by screening for antibody to HCV in 1990. Today, intravenous drug use and high-risk sexual activity are the most frequently identified risk factors associated with HCV infection. The prevalence of people with unknown HCV infection worldwide is high, so it is necessary to screen people with risk factors. The treatment of patients with chronic HCV infection who have not been treated previously should consist of interferon alpha (IFN-alpha) and ribavirin. Eur J Gastroenterol Hepatol 13:465-471 (C) 2001 Lippincott Williams & Wilkins
Kaplan-Meier V- and U-statistics
Get PDFIn this paper, we study Kaplan-Meier V- and U-statistics respectively defined as \theta (\widehat{F}_{n})=\sum _{i,j}K(X_{[i:n]},X_{[j:n]})W_{i}W_{j} and \theta _{U}(\widehat{F}_{n})=\sum _{i\neq j}K(X_{[i:n]},X_{[j:n]})W_{i}W_{j}/\sum _{i\neq j}W_{i}W_{j}, where \widehat{F}_{n} is the Kaplan-Meier estimator, \{W_{1},\ldots ,W_{n}\} are the Kaplan-Meier weights and K:(0,\infty )^{2}\to \mathbb{R} is a symmetric kernel. As in the canonical setting of uncensored data, we differentiate between two asymptotic behaviours for \theta (\widehat{F}_{n}) and \theta _{U}(\widehat{F}_{n}). Additionally, we derive an asymptotic canonical V-statistic representation of the Kaplan-Meier V- and U-statistics. By using this representation we study properties of the asymptotic distribution. Applications to hypothesis testing are given
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
MxA gene expression in peripheral blood mononuclear cells from patients infected chronically with hepatitis C virus treated with interferon-alpha
No full textHepatitis C virus (HCV) infection causes acute and often chronic liver disease. The treatment of choice is interferon-alpha (IFN-alpha). The proportion of patients responding to therapy in terms of a sustained virological response, however, is relatively low. One possible reason for the lack of effectiveness might be neutralization of the drug by host's inhibitory factors. Recent kinetic studies suggested that high doses of IFN-alpha, especially during the initial phase of therapy, might improve the virological response rates. Eighteen patients infected chronically with HCV were treated with IFN-alpha either at a standard dose (3 x 10(6) to 6 x 10(6) IU IFN-alpha three times weekly) for 6 to 12 months or with an intensified therapy (6 x 10(6) IU IFN-alpha daily) for at least one month. As surrogate parameter for the intracellular effect of the drug, MxA gene expression was quantified in RNA preparations from peripheral blood mononuclear cells. Beta-2-microglobulin (beta(2)M) concentrations were measured in serum. Serum HCV RNA titers were monitored in parallel. When compared to healthy individuals, untreated patients infected chronically with HCV were found to express 2.8-fold higher amounts of MxA specific transcripts. MxA gene expression and serum beta(2)M concentrations were found to be induced after administration of IFN-alpha, independent of the virological response not only during the initial phase of the intensified therapy but also over several months during standard therapy. It is concluded from these results that both early non-effectiveness of high dose IFN-alpha therapy as well as long-term non-effectiveness of standard therapy are not due to IFN-alpha inhibitory or neutralizing elements in serum. J. Med. Virol. 62:318-326, 2000. (C) 2000 Wiley-Liss, Inc
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
- …
