1,720,981 research outputs found
Statistical modeling for correlate of protection using accelerated failure time models and piecewise methods.
No full textChicken pox is an important childhood illness affecting mostly school-going children. The disease can be spread through contacts between infected and susceptible individuals. It is a very contagious disease caused by the varicella-zoster virus. Its main symptoms are: blister-like rash, tiredness, itching, and fever. Chicken pox can be serious, especially in adults, babies, and people with weakened immune systems. The objective of this study was to apply parametric survival models to determine whether there is a relationship between the risk of developing a varicella case and the titer obtained after vaccination and also to apply accelerated failure time models and the piecewise exponential model to determine the threshold that corresponds to the titer which best reflects the change in the risk of breakthrough varicella disease. In this analysis we applied the accelerated failure time models (Weibull model, the Log-logistic, the lognormal model) and the piecewise exponential model. Th
Statistical modeling for correlate of protection using accelerated failure time models and piecewise methods.
No full textChicken pox is an important childhood illness affecting mostly school-going children. The disease can be spread through contacts between infected and susceptible individuals. It is a very contagious disease caused by the varicella-zoster virus. Its main symptoms are: blister-like rash, tiredness, itching, and fever. Chicken pox can be serious, especially in adults, babies, and people with weakened immune systems. The objective of this study was to apply parametric survival models to determine whether there is a relationship between the risk of developing a varicella case and the titer obtained after vaccination and also to apply accelerated failure time models and the piecewise exponential model to determine the threshold that corresponds to the titer which best reflects the change in the risk of breakthrough varicella disease. In this analysis we applied the accelerated failure time models (Weibull model, the Log-logistic, the lognormal model) and the piecewise exponential model. Th
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Spatial and Temporal Heterogeneity of Malaria Transmission in sub-Saharan Africa
Full text linkThe past decade has seen a marked decline in malaria transmission and substantial progress towards malaria control in parts of Africa. A key tool in malaria control is the insecticide treated net (ITN). However, malaria remains a public health emergency in sub-Saharan Africa with children under five years of age bearing the greatest burden of the disease. In this thesis, I examine three sets of questions that are relevant to the changing epidemiology of malaria.
a) I investigated trends in malaria cases in Kilifi County on the Kenyan Coast over geographical area and over time, age, and the effectiveness of ITN use in the community. I observed a decline in the proportion of admitted children who had malaria parasites detected by microscopy from 1998 to 2009 as previously observed in some countries of sub-Saharan African. However, there was a steady and marked increase in the proportion of children with malaria parasites after 2009 accompanied by a shift in burden of disease from younger age groups to older age groups. Community ITN use was highly effective in reducing the risk of malaria. As transmission fell, geographical heterogeneity became
more marked.
b) I undertook an analysis of data shared from 19 studies conducted between 1996 and 2015 in 7 countries of sub-Saharan Africa to examine whether micro-geographical heterogeneity was generalizable. Hotspots were identified in all datasets, and were more marked at lower transmission intensity. Given the predictability with which hotspots occur as transmission intensity falls, malaria control programmes should have a low threshold for responding to apparent clustering of cases.
c) I then considered whether rapid diagnostic tests (RDTs) or PCR would alter detection of hotspots. Using cross-sectional studies of asymptomatic parasitaemia, I describe hotspots of malaria transmission in three sites on the Kenyan Coast using data from 8581 study participants. Microscopy and RDT missed a larger proportion of infections in low transmission settings. PCR hotspots completely overlapped with microscopy hotspots at a moderate transmission, but not at two low transmission setting. From this work, I recommend that malaria control programmes consider PCR testing for targeted control when transmission intensity is low
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
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
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