1,721,264 research outputs found
Broad-band jet emission in young and powerful radio sources: The case of the Compact Steep Spectrum quasar 3C186
Get PDFWe present the X-ray analysis of a deep (~200 ks) Chandra observation of the compact steep spectrum radio-loud quasar 3C 186 (z = 1.06) and investigate the contribution of the unresolved radio jet to the total X-ray emission. The spectral analysis is not conclusive on the origin of the bulk of the X-ray emission. In order to examine the jet contribution to the X-ray flux, we model the quasar spectral energy distribution, adopting several scenarios for the jet emission. For the values of the main physical parameters favored by the observables, a dominant role of the jet emission in the X-ray band is ruled out when a single-zone (leptonic) scenario is adopted, even including the contribution of the external photon fields as seed photons for inverse Compton emission. We then consider a structured jet, with the blazar component that—although not directly visible in the X-ray band—provides an intense field of seed synchrotron photons Compton-scattered by electrons in a mildly relativistic knot. In this case, the whole X-ray emission can be accounted for if we assume a blazar luminosity within the range observed from flat spectrum radio quasars. The X-ray radiative efficiency of such a (structured) jet is intimately related to the presence of a complex velocity structure. The jet emission can provide a significant contribution in X-rays if it decelerates within the host galaxy on kiloparsec scales. We discuss the implications of this model in terms of jet dynamics and interaction with the ambient medium
Drug-resistant tuberculosis
No full textPurpose of review: This review discusses the recent evidence on epidemiology, diagnosis, and treatment of drug-resistant and multidrug-resistant (MDR) tuberculosis (TB), an area where solutions for better diagnosis and treatment continually develop. Recent findings: The prevalence of drug resistance has been constantly rising during the recent years. It has peaked in eastern European countries such as Belarus, where a record of 35.5% MDR-TB amongst new cases have been reported from Minsk. New diagnostic tools are becoming available. Xpert MTB/RIF is by far the most promising of these new techniques. Clinical management of drug-resistant TB is still cumbersome. However, after over 40 years of neglect, new drugs are becoming readily available: delamanid, bedaquiline, and PA-824 combined into innovative regimens raise hopes for substantially higher success rates. Summary: The innovative diagnostic tools recently validated are changing the traditional paradigms of TB diagnosis, for too long based on sputum smear, culture, and drug susceptibility testing. New anti-TB compounds, which can be combined with several 'old' drugs with new indications, are gradually modifying the chances of cure for MDR-TB cases. Although initial evidence appears promising, the market use of new drugs must be accompanied by a serious public health approach aimed at preventing the development of further drug resistance. Copyright © 2013 Lippincott Williams & Wilkins
History of tuberculosis and drug resistance
No full textTo the Editor:
In their historical overview of global efforts to control tuberculosis, Keshavjee and Farmer (Sept. 6 issue)1 argue that the prioritization of global health funding based on measurable outcomes and high-return investments contributed to the fragmentation of primary health care. We agree but acknowledge that it can be difficult to strike the right balance between the improved efficiencies provided by vertical programs and comprehensive primary care. Importantly, international funding should not erode local ownership or investment in comprehensive primary care, which serves as the bedrock of a well-functioning health care system.
Global implementation of the DOTS (directly observed treatment, short-course) strategy eliminated the chaos that reigned in tuberculosis treatment during the early 1990s, curing 50 million people and averting some 7 million deaths.2,3 The absence of laboratory infrastructure, the unavailability of second-line drugs, and the failure to appreciate the epidemic potential of the disease motivated the initial exclusion of drug-resistant tuberculosis from the DOTS strategy, which was subsequently corrected with the formulation of the Stop TB Strategy.4,5 Urgent and bold action is required to curtail the threat of drug-resistant tuberculosis, including a major step-up in resources, political commitment, and unity of purpose from all involved in tuberculosis control
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
The role of IGRA in the diagnosis of tuberculosis infection, differentiating from active tuberculosis, and decision making for initiating treatment or preventive therapy of tuberculosis infection
No full textObjectives: The World Health Organization estimated that a quarter of the global population is infected by Mycobacterium tuberculosis (Mtb). A better control of tuberculosis (TB) is based on the ability to detect Mtb infection, identifying the progressors to TB disease, undergoing to preventive therapy and implementing strategies to register the infections and treatment completion. Design: we reviewed the literature regarding the tests available for TB infection diagnosis, the preventive therapies options and the cascade of care for controlling TB at a public health level. Results: current tests for TB infection diagnosis as IFN-γ release assays or tuberculin skin tests are based on the detection of an immune response to Mtb in the absence of clinical disease. The main limit is their low accuracy to detect progressors to disease. New preventive treatments are available with short duration that are associated with better adherence. Options to register TB infections are presented. Conclusions: Tests to diagnose TB infection are available but they lack accuracy to identify the progressors from infection to TB disease. Shorter preventive TB therapy are available but need to be implemented worldwide. A TB infection registry is crucial for improving the cascade of care leading to a better TB control
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
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