1,721,044 research outputs found
Evaluation of two commercial nucleic acid amplification tests for diagnosis of extrapulmonary tuberculosis from lymph nodes of children in Tanzania
Get PDFApproximately one third of the global population is latently infected with tuberculosis (TB) and there are approximately 9.6 million new cases of TB disease per year resulting in 1.5 million deaths. Eleven percent of cases globally occur in children and 81% of the burden of TB disease is borne by the developing world and countries with emerging economies (BRICS). The African region accounts for 28% of new TB cases globally.
TB remains a significant public health concern globally, particularly amongst children and immunocompromised individuals. Diagnosis of childhood TB is an on going challenge, as children usually do not present with the same signs and symptoms as adults, and are often misdiagnosed. Tuberculosis infection in children is seldom confirmed through sputum culture, as good sputum samples can rarely be collected. Only 15% of cases from children are sputum smear positive by acid-fast staining, and only 30%–40% are Mycobacterium tuberculosis (MTB) culture positive. Up to 40% of children present with extrapulmonary manifestations of TB disease. The most common manifestation is tuberculous lymphadenopathy. Good specimens for TB detection can be obtained from these cases through fine needle aspiration biopsy (FNAB), a cost-effective and practical out patient procedure for obtaining specimens from enlarged superficial lymph nodes.
The conventional laboratory techniques that have been used globally for TB diagnosis are Ziehl-Neelsen (ZN) staining for acid fast bacilli (AFB) microscopy, culture and more commonly now LED microscopy, cytological determination with auto-fluorescence staining and molecular Xpert® MTB/RIF (Cepheid) detection. AFB-microscopy requires minimally 5000 AFB per millilitre of specimen to yield a consistently positive result and observation of between 100 and 300 microscopic fields in order to obtain accurate results. Culture for MTB is the gold standard diagnostic method but has a slow turnaround time and requires laboratory resources that are not available in most parts of the world.
Recent systematic reviews of studies evaluating commercially available nucleic acid amplification test (NAAT) technologies confirm very high specificity, with sensitivity approaching, but not reaching, that of culture. The complexity and insufficient robustness of existing commercial NAAT protocols and their need for precision instruments, a high degree of technical support, and quality assurance make them unsuitable for most low resource TB endemic countries. In addition, none of these techniques have been fully validated for diagnosing TB in children and specifically not for extrapulmonary specimens.
In light of these challenges, there is promise in two technologies that have been developed and under evaluation over the last few years; the Xpert® MTB/RIF kit (Cepheid) for rapid detection of MTB and rifampicin resistance endorsed for use by the WHO; and the Ustar EasyNATTM TB IAD kit (Ustar Biotechnologies, Hangzhou) for detection of MTB, selected by the WHO as a technology on assessment for use in TB endemic countries. In this study, their performance was assessed against the conventional laboratory diagnostic techniques of smear AFB microscopy, cytology and mycobacterial culture of fine needle aspirates from lymph nodes of children suspected of TB lymphadenopathy in Tanzania.
Age defined clinical assessments were done for all 75 participants and TB treatment initiated based on these and/or laboratory diagnostic outputs. All laboratory diagnostic modalities were primarily assessed against TB culture as the conventional reference standard. As has been evidenced in earlier studies, the sensitivities for both smear microscopy and TB culture were very low in these extrapulmonary specimens. Lacking a true reference standard, composite reference standards (CRSs) were created to assess the performance of the test modalities under study. An alternative method for assessing diagnostic accuracy under these conditions is latent class analyses (LCA), which was utilized to further assess the performance of all diagnostic modalities in the study.
The overall outcomes of the project demonstrated that cytomorphology was a feasible and effective technique for detection of TB in lymph node aspirates (sensitivity: LCA 100%, specificity: LCA 94.7%) that may complement TB culture (sensitivity: LCA 74.5%, specificity: LCA 90.3%). Further, it was shown that Xpert (sensitivity: CRS 58% LCA 70.7%, specificity: CRS 93% LCA 94.2%) was superior in performance to EasyNAT (sensitivity: CRS 19% LCA 29.2%, specificity: CRS 100% LCA 100%) and ZN (sensitivity: CRS 14% LCA 19.1%, specificity: CRS 100% LCA 100%) analyses, respectively. Combining two or more tests significantly improved the diagnostic efficacy, but including either EasyNAT testing or ZN microscopy to a diagnostic algorithm that already had Xpert testing added no value.
These findings indicate that combining clinical assessment, cytology and Xpert MTB/RIF can provide for rapid and accurate diagnosis of childhood tuberculous lymphadenitis. Larger diagnostic evaluation studies on Xpert MTB/RIF would be required, to assess its use as a solitary initial test for tuberculous lymphadenitis in children
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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