1,720,991 research outputs found
Combining data analysis and transmission modelling to support the control and elimination of onchocerciasis in africa
No full textHuman onchocerciasis (river blindness) is a neglected tropical disease caused by Onchocerca volvulus and is transmitted by Simulium blackflies. The disease was once endemic across Latin America, Yemen and sub-Saharan Africa (SSA), the latter harbouring 99% of remaining disease burden. Onchocerciasis primarily causes disability, however, in high transmission settings, O. volvulus infection has also been linked to onchocerciasis-associated epilepsy (OAE), a known cause of premature mortality. Control efforts began in 1974 with anti-vectorial measures in West Africa. The introduction of mass drug administration (MDA) with ivermectin in 1987 has significantly reduced prevalence and morbidity, leading to elimination in some foci. The 2012 WHO NTD Roadmap set a target for elimination of transmission (EOT) in selected African countries by 2020. However, modelling studies in 2019 indicated that annual MDA alone may be insufficient, prompting calls for complementary interventions. The 2021-2030 WHO Roadmap set a goal of verifying EOT in 12 countries by 2030, recognising challenges in achieving EOT everywhere under current strategies. This thesis employs EPIONCHO-IBM, an individual-based transmission model, to examine hypoendemic transmission dynamics and the risks of re-introduction. Key findings indicate that onchocerciasis transmission may persist at low annual biting rates (ABR) without importation, with threshold biting rates as low as 70 bites per person per year. This suggests that low-prevalence settings should be included in MDA programmes. Modelled anti-Ov16 seroprevalence thresholds align with WHO guidelines, reinforcing the need for a conservative approach when initiating MDA. Modelling also highlights that immigration of infected individuals poses a significant risk to elimination efforts. Additionally, by integrating OAE into EPIONCHO-IBM, the thesis quantifies the impact of ivermectin MDA on OAE prevalence and underscores the need for alternative treatments, such as moxidectin, for young children. These findings contribute to refining onchocerciasis transmission models and advancing elimination strategies across SSA.Open Acces
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
Mathematical modelling to support the elimination of onchocerciasis transmission
No full textHuman onchocerciasis is a neglected tropical disease (NTD) caused by the filarial nematode Onchocerca volvulus (Filarioidea: Onchocercidae) and transmitted by the bites of Simulium (Diptera: Simuliidae) blackflies. The disease is or has been endemic in 37 countries, with the majority (30) in sub-Saharan Africa, 6 in Latin America and 1 in the Eastern Mediterranean region (Yemen). Large-scale mass drug administration for onchocerciasis control became possible from the late 1980s with the donation of ivermectin by Merck & Co. Inc. With the success of onchocerciasis control programmes, the primary goal of onchocerciasis treatment (in Africa specifically) shifted from morbidity control to the elimination of the infection where feasible by 2020 and in 80% of endemic countries by 2025. In the new World Health Organization roadmap on NTDs, the goals for onchocerciasis were reformulated as verification of elimination of transmission in 12 countries by 2030. However, the feasibility of achieving and maintaining the proposed elimination goals remains unclear. With the deadlines for the proposed goals rapidly approaching, and with many countries unlikely to reach the elimination goals with ivermectin alone, the focus has increasingly shifted to identifying alternative strategies aimed at accelerating progress towards elimination.
Mathematical models of onchocerciasis have been used to provide quantitative guidance on time horizons to elimination, health impact, economic cost and cost-effectiveness, and the efficacy of potentially novel treatment strategies. The central aim of this thesis is to use EPIONCHO-IBM, a recently developed stochastic individual-based transmission model of onchocerciasis transmission and control in communities of Africa, to support efforts towards the elimination of onchocerciasis in Africa.
The first half of the thesis focuses primarily on moxidectin, a milbemycin macrocyclic lactone recently approved for the treatment of human onchocerciasis. Moxidectin represents a potential tool to accelerate progress towards elimination given its superior efficacy to ivermectin in both Phase II and Phase III clinical trials. The thesis first reviews the current literature on moxidectin’s pharmacology and clinical trials, and discusses the potential of moxidectin to accelerate onchocerciasis elimination. Subsequent chapters aim to understand the potential epidemiological impact of moxidectin in the context of onchocerciasis control programmes that currently rely on mass ivermectin administration. EPIONCHO-IBM is parameterised to capture the single-dose effects of moxidectin and ivermectin. The effects of a single treatment were extended to evaluate are compare the ability of both drugs to suppress onchocerciasis transmission and achieve local elimination given multiple rounds of treatment. EPIONCHO-IBM is also used to explore potential effects that could impact control efforts with moxidectin and ivermectin but which have not been fully evaluated. This includes inter-individual variation in treatment responses to ivermectin and moxidectin using individual data from the Phase III clinical trial of moxidectin, and the potential prophylactic effects of ivermectin and moxidectin on pre-adult larvaal stages of O. volvulus by combining data on each drug’s inhibitory effect in vitro and kinetics in vivo.
The second half of the thesis focuses on re-evaluating and refining modelling assumptions to more accurately model onchocerciasis transmission and control. Accurately modelling who is treated within the population is an important factor for model dynamics. Therefore, EPIONCHO-IBM’s current compliance model, which governs who takes treatment at a given round, is evaluated and improved by using the more flexible beta-binomial distribution. The two models of compliance are compared on their ability to capture data on the number of rounds taken by individuals in onchocerciasis control programmes as well as the impact on EPIONCHO-IBM predictions.
Blackfly biting rates are a key determinant of both the intensity of onchocerciasis transmission and the likely success of interventions. Data from recently developed immunoassays to measure antibodies against blackfly saliva antigens are analysed as a potential tool to measure exposure to blackfly bites. The analysis incudes both a statistical and mechanistic analysis of the data, including the uses of antibody acquisition models designed to capture the change in antibody levels with age and sex, as a tool to identify patterns of age- and sex-specific exposure to blackfly bites under different immunological assumptions.
Finally, challenges for both onchocerciasis modelling and the development of EPIONCHO-IBM are discussed, highlighting some of the outstanding issues that should be evaluated for mathematical models of onchocerciasis to be as helpful as possible in the global fight to eliminate onchocerciasis transmission.Open Acces
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
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
- …
