1,721,063 research outputs found
Preventing HIV in resource-limited settings: evidence for action, from cross-sectional surveys
Full text linkNeighbourhood prevalence-to-notification ratios for adult bacteriologically-confirmed tuberculosis reveals hotspots of underdiagnosis in Blantyre, Malawi
Full text linkLocal information is needed to guide targeted interventions for respiratory infections such as tuberculosis (TB). Case notification rates (CNRs) are readily available, but systematically underestimate true disease burden in neighbourhoods with high diagnostic access barriers. We explored a novel approach, adjusting CNRs for under-notification (P:N ratio) using neighbourhood-level predictors of TB prevalence-to-notification ratios. We analysed data from 1) a citywide routine TB surveillance system including geolocation, confirmatory mycobacteriology, and clinical and demographic characteristics of all registering TB patients in Blantyre, Malawi during 2015-19, and 2) an adult TB prevalence survey done in 2019. In the prevalence survey, consenting adults from randomly selected households in 72 neighbourhoods had symptom-plus-chest X-ray screening, confirmed with sputum smear microscopy, Xpert MTB/Rif and culture. Bayesian multilevel models were used to estimate adjusted neighbourhood prevalence-to-notification ratios, based on summarised posterior draws from fitted adult bacteriologically-confirmed TB CNRs and prevalence. From 2015-19, adult bacteriologically-confirmed CNRs were 131 (479/371,834), 134 (539/415,226), 114 (519/463,707), 56 (283/517,860) and 46 (258/578,377) per 100,000 adults per annum, and 2019 bacteriologically-confirmed prevalence was 215 (29/13,490) per 100,000 adults. Lower educational achievement by household head and neighbourhood distance to TB clinic was negatively associated with CNRs. The mean neighbourhood P:N ratio was 4.49 (95% credible interval [CrI]: 0.98-11.91), consistent with underdiagnosis of TB, and was most pronounced in informal peri-urban neighbourhoods. Here we have demonstrated a method for the identification of neighbourhoods with high levels of under-diagnosis of TB without the requirement for a prevalence survey; this is important since prevalence surveys are expensive and logistically challenging. If confirmed, this approach may support more efficient and effective targeting of intensified TB and HIV case-finding interventions aiming to accelerate elimination of urban TB
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
Tuberculosis among people living with and without HIV in lower-income countries: Transmission, Resistance, Mortality.
Full text linkTuberculosis (TB), an airborne disease caused by the bacterium Mycobacterium tuberculosis (Mtb), is one of the most deadly infectious diseases, with an estimated 10 million newly diagnosed TB cases and 1.4 million deaths per year worldwide. The HIV pandemic and the emergence of drug-resistant Mtb strains are the main challenges to TB control, especially in low-and middle-income countries. HIV infection induces immunodeficiency and is a decisive risk factor for TB. With the significant scale-up of antiretroviral therapy (ART) for people living with HIV (PLHIV), their prognosis has improved and reduced TB incidence in this population. Nevertheless, the risk of TB in PLHIV on ART remains higher than in people without HIV. In addition, the diagnosis of TB in PLHIV is more challenging due to the reduced occurrence of lung cavitation and lower bacterial load in the sputum compared to HIV-negative people. The rising number of drug-resistant TB is another threat to the control of TB. To prevent drug-resistant TB, strategies such as surveillance, access to comprehensive drug susceptibility testing (DST), rapid treatment initiation and treatment completion with an appropriate regimen are still lacking in many low-and middle-income countries.
In this thesis, I explore different aspects of the epidemiology of TB, especially drug-resistant TB in PLHIV and HIV-negative people seeking care in low-and middle-income countries. I will focus on Mtb transmission, the management of TB in adults (age ≥16 years) from diagnosis to treatment and clinical outcomes, and the evolution of drug-resistant Mtb and the clinical consequences.
In chapter 1, I provide an introduction to TB. I describe the global burden of TB, the pathogen and the course of infection, the genetic diversity of TB, the diagnosis of TB including DST and the treatment of pan-susceptible and drug-resistant TB. In addition, I describe the current challenges to the control of TB.
Chapter 3 and chapter 4 focus on the transmission of Mtb at a primary care clinic in South Africa using a novel approach. Paper 1 is the study protocol, which describes the range of collected patient and environmental-associated data in detail. In paper 2, I showed that the risk of Mtb transmission increased with the presence of young adults and higher room humidity at the primary care clinic. During a clinic visit of one hour, the risk of infection was between 3-5% and increased to 9-29% for patients with monthly visits.
Chapter 5 and chapter 6 focus on the management of TB in adult PLHIV at ART clinics in low-and middle-income countries. In paper 3, I analysed clinical data of 2,695 adult PLHIV who developed TB, of whom 1,930 (72%) had pulmonary TB, and 765 (28%) had extra-pulmonary TB. I demonstrated the difficulties in obtaining bacteriological confirmation in PLHIV who also had pulmonary TB or extra-pulmonary TB (52% and 42%). I found no association between the increased mortality in PLHIV and the type of TB they developed (extra-pulmonary or pulmonary). I showed that bacteriological confirmation was associated with reduced mortality in PLHIV who had pulmonary TB or extra-pulmonary TB than PLHIV with a negative diagnostic result. Paper 4 used site-level data to study the integration of multidrug-resistant TB (MDR-TB) services at 29 ART clinics. I show that 14 (48%) ART clinics reported full MDR-TB services on-site, nine (31%) reported partial integration, and six (21%) had access to off-site MDR-TB services only. I demonstrated that the 22 clinics with on-site molecular DST could identify drug resistance to first-line drugs but rarely to second-line drugs. In addition, I showed that ART clinics with full integration of MDR-TB services were more likely to prescribe individualised MDR-TB treatment compared to off-site services.
Chapters 7 to 10 focus on the evolution of drug-resistant Mtb and clinical consequences. In paper 5 and 6, I examined mortality in adult PLHIV and HIV-negative adults who developed TB in seven low-and middle-income countries. I compared mortality by DST results done locally that were discordant or concordant with the results from the reference laboratory using culture-based phenotypic DST or WGS. In both studies, the degree of drug resistance, discordant DST results potentially leading to under-treatment and discordant DST results, which resulted in under-treatment according to WHO guidelines, led to increased mortality, especially among those with drug-resistant TB. Further, I demonstrate that DST for second-line drugs was rarely available locally. Paper 7 showed that mutation with low-fitness in rpoB variants is more likely in PLHIV who also had rifampicin-resistant TB than in HIV-negative people who had rifampicin-resistant TB. Finally, paper 8 demonstrated that drug resistance to delamanid occurred in people with TB who were drug naïve to delamanid.
In this thesis, I provide insights into different aspects of the epidemiology of TB, from Mtb transmission, management of TB, and drug resistance to death, but also identify the gaps in our current knowledge. I show that new approaches can be used to study Mtb transmission. I demonstrate the challenges of diagnosing PLHIV and pulmonary or extra-pulmonary TB at ART clinics in low-and middle-income countries. In addition, I show that DST to second-line drugs is limited in many low-and middle-income countries, and there is a need for more rapid and comprehensive DST testing to ensure appropriate treatment. My survey on integrated MDR-TB services also showed that 48% of ART clinics had full integrated MDR-TB services. I showed that low-fitness mutations in rpob are more likely in PLHIV who have rifampicin-resistant TB than in HIV-negative people who had rifampicin-resistant TB and that drug resistance can occur in people natïve to delamanid. In conclusion, to control TB, we need to strengthen the access and use of point-of-care diagnostic tests to diagnose TB disease and DST for first- and second-line anti-TB drugs and access to second-line anti-TB drugs in low-and middle-income countries. In addition, we need to improve surveillance of drug-resistant TB and better treatment options to ensure the completion of the treatment
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
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
- …
