1,721,083 research outputs found
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
Modelling to guide the development of pharmaceutical interventions against malaria
Full text linkThe development of new antimalarial compounds and regimens is more urgent than ever as continued burden reduction and ultimately the elimination of malaria are threatened by emerging resistance against current treatments, and sub-optimal adherence to treatment schedules.
Throughout this thesis, I have sought to develop a thorough understanding of parasite-host dynamics along the clinical development pathway of new antimalarials for clinical case management and to evaluate drug efficacy measures, their translation, and their limitations. I analysed parasite growth data from murine and human experiments in the absence of treatment and captured parasite growth in an ensemble of mechanistic mathematical models. Subsequently, I investigated the sensitivity of the experimental efficacy endpoint of parasite clearance after treatment to host-, parasite-, and drug-dynamics throughout the clinical development pathway. Our findings show that the experimental background and/or host dynamics strongly influence parasite clearance with differential impact between the experimental systems. The work culminates in a discussion of the multitude of different host-parasite dynamics in the development stages that compromise the translatability of drug efficacy estimates between the infection experiments.
I then shift the focus to the development of new anti-infective interventions in form of long acting injectables. These are envisioned to protect children living in highly seasonal transmission settings against malaria. I employ a simulation-based approach using an individual-based stochastic model of malaria that allows the efficient investigation of a large range of plausible product properties and deployment modalities and their potential to reach predefined health and impact targets. A non-inferiority analysis to currently implemented drug-based chemoprevention measures reveals the trade-offs between tool and coverage optimisation for the development of new tools. The results assist the specification of use cases and definition of efficacy targets in target product profiles to guide the future development of long-acting injectables.
Through the use of mechanistic parasite growth and individual-based models, the work reported here creates a sound foundation for a comprehensive assessment of experimental and clinical testing results through exploring, understanding and quantifying host-, parasite-, and experimental-factors that influence intervention efficacy and impact
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
Estimating the patterns and consequences of malaria transmission dynamics on fine spatial scales
Full text linkPlasmodium falciparum is the leading cause of malaria infection and a major cause of morbidity and mortality across the globe, particularly in the African region. The burden of malaria is unevenly distributed, with some countries, districts or even households within villages harboring a disproportionally higher burden. There is an intricate relationship between the mosquito vector, humans and the parasites they carry, and how they interact with the environment. Small movements on a fine-scale lead to the patterns observed in the community. Quantifying transmission dynamics on a fine-scale, how malaria infections spread locally and the processes leading to the observed spatial and temporal distribution patterns is important for many aspects of malaria epidemiology, in particular, the design of targeted interventions against malaria, the design of studies to evaluate the effectiveness of vector control in the field, and the parameterization of mathematical models to predict the likely impact of interventions for settings where data is not available.
Mathematical and statistical models have been developed to quantify fine scale malaria transmission dynamics and investigate the effects of interventions. Since data on the spread of vectors and parasites is challenging to collect, it is not available from many endemic settings for analytic methods to provide estimates, or to validate model predictions. Due to variability between settings, findings from one setting cannot be easily generalized. There is thus a need to involve methods that can extract information from imperfect but available datasets, to make the most of the existing data sources from settings with a variety of characteristics.
The overall aim of this thesis was to use statistical and mathematical modelling approaches to characterize fine scale malaria transmission dynamics and their consequences on the measurement of heterogeneity on a local scale for targeted interventions.
Chapter 2 used an established comprehensive simulator of malaria epidemiology developed at the Swiss Tropical and Public Health Institute (Swiss TPH) to predict the proportion of malaria infections that are in mosquitoes and humans and how this varies by setting specific characteristics. A substantial proportion of infections was predicted to be in mosquitoes, to vary with setting specific characteristics, and in response to interventions. The predictions also highlighted the role of the dynamics of infections in humans and mosquitoes following the introduction or scale-up of interventions.
In Chapter 3, a statistical model which takes into account movement between houses in a village to estimate how far and where mosquitoes fly to in the presence of spatial repellents was developed. This was a secondary use of data on mosquito densities. The method evaluation using simulation showed that the model could be used as a potential tool to gain information on mosquito movement, estimating the distance between the houses the mosquitoes were repelled from and the houses they move to, the proportion of mosquitoes repelled, and the proportion of repelled mosquitoes moving to another house as opposed to somewhere outside. However, the trial data needs to contain sufficient information to be able to disentangle the effects of the underlying processes and provide accurate estimates for all the parameters. We found that additional data on the total number of mosquitoes and sufficient numbers of mosquitoes repelled were required in the case of the motivating trial. Findings from the simulations could inform the design of studies and help quantify criteria for trial settings.
In Chapter 4, a simulation method was developed and applied to data on parasite genotypes from Kilifi County, Kenya. A previous study found an interaction between time and geographical distance on the genetic difference between pairs of parasite genotypes: genetic differences were lower for pairs of parasite genotypes which were evaluated within a shorter time interval and found within a shorter geographic distance apart. A stochastic individual-based model of malaria infections, people and homesteads was developed and fitted to the genetic differences in order to investigate hypotheses and parameter values consistent with the observed interaction.
The observed interaction could be reproduced by the individual-based model. Although hypothesis about immunity to previously seen genotypes, and or a limit on the number of current infections per individual could not be ruled out, they were not necessary to account for the observed interaction. The mean geographical distance between parent and offspring infections was estimated to be 0.40km (95%CI 0.24 – 1.20), in the base model. This was the first modeling study that we know of which has attempted to estimate parameter values and test hypotheses from malaria genotyping data with a low coverage of infections in a setting with moderate transmission. The findings glean some insights on how simulation can be used in quantifying factors driving transmission, and in estimating unknown parameters when analytic methods are limited.
The work in Chapter 5 uses the simulation model developed in Chapter 4 to investigate how the method chosen, local seasonality and movement of infections influence the detection of areas of higher transmission on fine spatial scales for targeted interventions. Our findings show that the identification of hotspots was less accurate when there was a gentle decay in risk from the hotspot boundary, the hotspot was irregularly shaped, there was seasonality in the area or when the mean distance between parent and offspring infections was longer. The findings highlight the importance of setting characteristics, the choice of outcome, and method of detection on the accuracy of identifying areas of higher transmission for targeted interventions. The underlying fine scale transmission dynamics should be taken into account when performing and interpreting analyses of heterogeneity for targeted interventions.
Taken as a whole, this thesis provides information on the characteristics of transmission dynamics on a fine scale. It highlights that a substantial proportion of malaria infections are in mosquitoes, and places emphasis on the role that vectors, and humans play in the spread of infections and the implications of fine scale movement for the measurement of heterogeneity for targeted interventions. The estimates have implications for the design and evaluation of malaria control and elimination interventions
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
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