1,721,091 research outputs found
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
Clinical and cost effectiveness of surgery for morbid obesity: a systematic review and economic evaluation
No full textOBJECTIVE: To assess the clinical and cost effectiveness of surgery for people with morbid obesity. DESIGN: A systematic review of randomised control trials (RCTs), prospective clinical trials and economic evaluations identified from 14 electronic databases (including Medline, Cochrane library and Embase from their inception to October 2001), bibliographies and consultation with experts and manufacturers was performed to assess the clinical and cost effectiveness of different surgical procedures and nonsurgical management for morbid obesity. An economic evaluation was undertaken to assess cost effectiveness in the UK. SUBJECTS: People diagnosed as morbidly obese, defined as a body mass index (BMI) (weight in kilograms/height in metres(2)) >40 kg/m(2), or with a BMI>35 kg/m(2) with serious comorbid disease, in whom previous nonsurgical interventions had failed. MEASUREMENTS: The outcomes assessed included weight change, quality of life, peri- and postoperative morbidity and mortality, revision rates and obesity comorbidities. Cost effectiveness was modelled from these data and presented as cost per quality-adjusted life year (QALY). RESULTS: Included studies differed in methodological quality. Surgery resulted in a significantly greater loss of weight (23-37 kg more weight) than nonsurgical treatment, which was maintained to 8 years and led to improvements in quality of life and comorbidities. The economic evaluation of surgery compared with nonsurgical management suggested that surgery was cost effective at pound 11000 per QALY. Comparisons of the different types of surgery were equivocal. CONCLUSION: Surgery for morbid obesity appears to be clinically and cost effective. Because of the nature of the evidence, particularly the uncertainty in the clinical and economic evaluations, it is difficult to distinguish between the different surgical procedures.<br/
Pegaptanib and ranibizumab for neovascular age-related macular degeneration: a systematic review
No full textAIMS: To assess the clinical effectiveness of pegaptanib sodium and ranibizumab for neovascular age-related macular degeneration (AMD). METHODS: A systematic review of randomised controlled trials (RCTs) identified through searching 12 electronic databases, bibliographies and consultation with experts and manufacturers. RCTs were eligible if they assessed the effects of pegaptanib orranibizumab with best supportive care, sham injection or photodynamic therapy (PDT) on patients with subfoveal choroidal neovascularisation associated with wet AMD and examined outcomes including visual acuity and adverse events. RESULTS: Three RCTs of ranibizumab (MARINA, ANCHOR, FOCUS) and two of pegaptanib (VISION study) met the inclusion criteria. The RCTs included patients with different lesion types. The studies showed statistically significant benefit on different measures of visual acuity for patients receiving pegaptanib, ranibizumab orranibizumab with PDT compared to control (sham injection, PDT or sham injection with PDT) after 12 months. These differences appeared to be clinically significant. Although adverse events were common among those receiving pegaptanibor ranibizumab, they were considered mild to moderate in nature. Meta-analysis of ranibizumab trials and indirect comparison of the two drugs were not possible due to differences in the study populations' lesion types. However, results from the RCTs of ranibizumab tended to show a greater effect on visual acuity than resultsfrom the RCT of pegaptanib. CONCLUSIONS: Pegaptanib and ranibizumab appear to slow or stop the progression of neovascular AMD. Uncertainty remains over the relative benefits of pegaptanib compared with ranibizumab and other unlicensed drugs (eg, Avastin), due to the nature of the evidence. Head-to-head RCTs and economic evaluations comparing these alternatives are needed.<br/
Tenofovir disoproxil fumarate for the treatment of chronic hepatitis B
No full textThis paper presents a summary of the evidence review group (ERG) report into the clinical effectiveness and cost-effectiveness of tenofovir disoproxil fumarate for the treatment of chronic hepatitis B, in accordance with the licensed indication, based upon the evidence submission from Gilead to the National Institute for Health and Clinical Excellence (NICE) as part of the single technology appraisal process. The submitted clinical evidence included two international randomised controlled trials (RCTs) comparing tenofovir with adefovir, and a mixed treatment comparison (MTC) using Bayesian methodology to compare tenofovir with other nucleos(t)ide analogues using direct and indirect RCT evidence. There were no statistically significant differences between tenofovir and adefovir in overall adverse events although, in hepatitis B 'e' antigen (HBeAg)-positive patients, there was a higher incidence of mild nausea in the tenofovir treatment group. The primary outcome, 'complete response', was a composite end point defined as histology response and hepatitis B virus DNA below 400 copies/ml. For both HBeAg-positive and HBeAg-negative patients, a significantly greater proportion had a complete response after 48 weeks with tenofovir than with adefovir. There was no statistically significant difference in histological response in either group of patients compared with adefovir. The MTC could only generate results for HBeAg positive nucleos(t)ide naive patients as there was insufficient evidence for other subgroups. The probability of achieving undetectable HBV DNA with tenofovir was found to be significantly higher than that for all other treatments considered in the analysis at the 0.05 level. The analysis demonstrated that there is a 98% probability that tenofovir is the most potent nucleos(t)ide in terms of this outcome. The manufacturer's submission concluded that tenofovir is a cost-effective option as first-line treatment. For HBeAg-positive patients, tenofovir followed by lamivudine has an incremental cost-effective ratio (ICER) of 9940 pounds per quality-adjusted life-year (QALY) gained, compared with lamivudine followed by tenofovir. A more appropriate treatment strategy of tenofovir followed by tenofovir plus lamivudine has an ICER of 13,619 pounds per QALY gained, compared with lamivudine followed by tenofovir. For HBeAg-negative patients, tenofovir followed by lamivudine has an ICER of 9811 pounds per QALY gained, compared with best supportive care. A more clinically appropriate treatment strategy of tenofovir followed by tenofovir plus lamivudine has an ICER of 13,854 pounds per QALY gained, compared with tenofovir followed by lamivudine. The ERG uncovered a number of errors in the submission and these ICERs approximately doubled when the analysis was corrected and reran. The guidance issued by NICE on 22 July 2009 states that tenofovir disoproxil, within its marketing authorization is recommended as an option for the treatment of people with chronic HBe-Ag-positive or HBe-Ag-negative hepatitis B in whom antiviral treatment is indicated.<br/
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
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