1,720,967 research outputs found
A studentized permutation test for the non-parametric Behrens-Fisher problem
No full textFor the non-parametric Behrens-Fisher problem a pen-nutation test based on the studentized rank statistic of Brunner and Munzel is proposed. This procedure is applicable to count or ordered categorical data. By applying the central limit theorem of Janssen, it is shown that the asymptotic permutational distribution of this test statistic is a standard normal distribution. For very small and very different sample sizes, frequently occurring in medical and biological applications, an extensive simulation study suggests that this permutation test works well for data from several underlying distributions. The proposed test is applied to data from a clinical trial. (c) 2006 Elsevier B.V. All rights reserved
Sensitivity and specificity of qualitative muscle ultrasound in assessment of suspected neuromuscular disease in childhood
No full textMuscle ultrasound is considered a useful noninvasive technique for visualizing normal and pathological skeletal muscle. We determined the accuracy of qualitative muscle ultrasound in the discrimination of normal muscle from myopathic, neurogenic, and unspecifically abnormal tissue changes in the evaluation of suspected NMD in childhood. Sensitivity and specificity of muscle ultrasound were assessed by comparing sonographic classification of muscle tissue changes in 134 children with definitive diagnosis as provided by muscle histology or mutation analysis performed subsequently to the sonography. We found a sensitivity of 81 % and a specificity of 96% for detection of any abnormal muscle tissue alteration by ultrasound. For detection of neurogenic changes, sensitivity was 77% with even higher specificity (98%). Accuracy was slightly lower for myopathic changes (79%) and clearly lower for unspecific abnormal tissue alterations (70%). Accuracy of ultrasound was lower in younger children. High reliability of muscle sonography justifies a more widespread use of this method in evaluation of suspected NMD in childhood. (C) 2007 Elsevier B.V. All rights reserved
Implementing a hospital-based smoking cessation programme: Evidence for a learning effect
No full textObjective: This study assessed a newly set-up, hospital-based smoking cessation clinic with regard to continuous abstinence rates and the effectiveness of concomittant nicotine replacement therapy. Methods: Smoking status of 369 participants of this 8-week cognitive-behavioural smoking cessation group programme was obtained using exhaled carbon monoxide at the end of the course as well as self-report 6 months after the course. In addition to demographic data, FTND score, SDS score, and usage of nicotine replacement products were recorded. Results: Overall, 29.8% of all participants reported to have been continuously abstinent for 6 months after the course. Success rates increased significantly during the first year after initiation of the programme (from 15 to 35%, p < 0.001), indicating a learning process of the staff running the course. Nicotine replacement therapy was used by 51.3% of participants, but 58% of these discontinued its use within 5 weeks. Nicotine substitution for more than 5 weeks was associated with a 50% success rate after 6 months. Conclusions: Our data indicate a learning effect of smoking cessation course staff and a possible minimum duration required for nicotine replacement to be effective. Practice implications: The observed learning effect in smoking cessation programmes should be considered when evaluating newly established interventions of this kind. Patients tend to stop nicotine replacement therapy too early, thereby decreasing their chances of middle-term abstinence. (C) 2007 Elsevier Ireland Ltd. All rights reserved
Growth hormone response to low-dose apomorphine in restless legs syndrome
No full textIntroduction.- Low-dose apomorphine challenge has been shown to cause a rise in growth hormone (GH) in patients with Parkinson's disease (PD). This was interpreted as an increased postsynaptic sensitivity of hypothalamic dopamine receptors in the course of a generalized degeneration of doparninergic neurons. The dopaminergic system in the restless legs syndrome (RLS) has been assumed to play a role in its pathophysiology. It is therefore the aim of this study to determine whether the GH response to subcutaneously applied low-dose apomorphine is generally altered in patients with RLS as compared to healthy controls. Patients and methods.- We examined 40 patients with idiopathic RLS as well as 20 age- and sex-matched healthy control subjects by means of the low-dose apornorphine test. GH was analyzed at baseline, as well as 45 and 60 min after subcutaneous low-dose apomorphine injection in the morning. Results.- Forty RLS patients (58.3 +/- 11.9 years, 32 females) with a mean RLS severity scale score of 23.9 +/- 6.6 (range 10-37) were examined. GH was not significantly increased 45 and 60 min after injection (p = 0.397) (2.44 +/- 2.35 ng/ml at baseline versus 2.71 +/- 2.29 ng/ml after 45 min and 2.18 +/- 1.83 ng/ml after 60 min). The results were independent of pre-treatment with levodopa. Age, sex, duration, and severity of the disease did not show a covariate effect with GH levels. There was no difference compared with healthy controls. Conclusions: RLS patients did not show an increase in GH after stimulation with low-dose apomorphine. Lack of sensitivity alteration of extrastriatal hypothalamic dopamine receptors suggests that RLS is not a general doparninergic degenerative disease or might only show circadian alterations. (c) 2007 Elsevier Ltd. All rights reserved
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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