1,720,983 research outputs found
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
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
Dissecting patient macrophage responses to Mycobacterium tuberculosis Complex strains from Tanzania and assessing T cell biomarkers for TB diagnosis and treatment monitoring
Get PDFTuberculosis (TB) has existed throughout human history, traced back to 9000 years ago to date. TB is transmitted through inhalation of infective air droplets from an infected person to the next susceptible host. This devastating disease has been a major cause of death from a single infectious agent more than HIV/AIDS and malaria combined before the COVID-19 pandemic. Caused by several genetically distinct Mycobacterium tuberculosis complex (MTBC) species, TB causes the death of a person every 22 seconds making MTBC one of the most successful human pathogen. TB is mostly curable with a specific combination of anti-TB drugs. Yet the increase of strains carrying drug-resistance mutations and the gap between people who are not diagnosed contributes to the reported TB related deaths. Ending this ongoing epidemic will require investment in biomedical, public health and socioeconomic interventions to sustain the necessary research and development of the necessary tools. Improvement of current diagnostic tests and development of new diagnostic approaches is necessary to increase case detection rates and close in the 4.2 million gap of people who are currently missed every year. In addition, genetically distinct MTBC lineages are differentially distributed globally; further understanding of the link between this diversity and MTBC pathogenesis is likely to improve management of TB patients in different epidemiological settings.
In the first part of this thesis, we hypothesized that TB disease epidemiology in Tanzania is driven by the human-MTBC genetic interactions resulting in an increased susceptibility of specific hosts to a specific circulating MTBC strain. This hypothesis was investigated in Chapter 3, where I will first give detailed introduction of the human adapted MTBC lineages, their distribution and factors contributing to their global distribution. I will then introduce current concepts of strain adaptation to local host populations driven by genetic interaction between human hosts and the circulating strains in various epidemiological settings. To test our hypothesis, we selected representative MTBC strain endemic to the Temeke District of Dar es Salaam where patients were recruited, and peripheral blood mononuclear cells cryopreserved. Patient-derived macrophages from monocytes isolated from their collected blood were infected either with a genetically related strain that had originally infected the patient (“matched infection”) or with other endemic lineages (“mismatched infection”). MTBC replication within patients’ macrophages as well as cytokine and chemokine production in response to infection were assessed. We observed that lineage-matched ex-vivo infection of macrophages derived from TB patients could not deliver sympatric associations signals. In turn, our results suggest that TB epidemiology in Tanzania is mainly driven by different MTBC strain-specific pathogenesis strategies rather than host-specific genetic traits.
In the second part of this thesis, we explored the hypothesis that bacterial load perception by the host adaptive immune system results in a measurable activation status that can be used to: i) diagnose TB infection and; ii) monitor disease resolution. This work is presented in Chapter 4 in which we investigated the diagnostic potential of two T-cell activation markers (TAM) for TB diagnosis (TAM-TB assay). The TAM-TB assay was assessed using a simplified protocol starting from 1ml of blood to comply with childhood TB diagnosis. In this chapter, I will introduce the current TB diagnostic tools, their limitations and provide reasons supporting the implementation of the TAM-TB assay in the field. I will then detail how we assessed the diagnostic performance of the TAM-TB assay for TB diagnosis starting from 1ml of blood from 479 active TB patients and 108 symptomatic controls. I will present how sample processing was done to measure expression of CD38 or CD27 by CD4 T cells producing IFN-γ and/or TNF-α in response to a synthetic peptide pool covering the sequences MTBC ESAT-6, CFP-10 and TB10.4 antigens using a 4-color FACSCalibur apparatus. The CD38-based TAM-TB assay specificity reached 93.4% for a sensitivity of 82.2% with an area under the receiver operating characteristics curve of 0.87 (95% CI 0.84-0.91). I will demonstrate how TAM-TB routine testing with a 24h turnaround time at district level in a resource-limited setting was successfully implemented. Starting from 1ml of blood and being not affected by HIV status, I will conclude that CD38-based TAM-TB assay performance appears closely compatible with the optimal target product profile accuracy criteria defined by WHO for a non-sputum confirmatory TB test.
In Chapter 5, we explored the use of the TAM-TB assay as proxy of host bacterial load and consequently, a treatment-monitoring tool. In this chapter, I will introduce why treatment monitoring is important not only for patient management but also for clinical trials evaluating new treatment regimens. I will also develop the shortcomings of current tools used to measure bacterial load and disease resolution and the need for alternative measures. In this work, we hypothesized that the phenotype of MTBC-specific T cells may be quantitatively impacted by the load of bacteria present in a given patient. To test this hypothesis, we obtained 1 ml blood from 105 active TB patients, before and after 5 months of antibiotic treatment. We evaluated the relationships between patients’ clinical characteristics of disease severity and microbiological as well as molecular proxies of bacterial load in sputum at the time of diagnosis. Reflecting the difficulty to extrapolate bacterial burden from a single end-point read-out, we observed statistically significant but weak correlations between Xpert MTB/RIF, MBLA and time to culture positivity. We demonstrated that resolution of CD38 expression by antigen-specific T cells was observed readily following 5 months of antibiotic therapy. However, the intensity of CD38-TAM signals measured at diagnosis did not significantly correlate with MTBC 16S rRNA or rpoB DNA detected in patients’ sputa. Altogether, our data support CD38-TAM as an accurate marker of infection resolution independently of sputum bacterial load. The CD38-based TAM-TB assay constitutes a promising assay to monitor treatment response.
In summary, in this thesis I dissected the influence of both human and MTBC genetic variability in the epidemiology of TB in Tanzania to an unprecedented extent matching endemic strains to infect patient’s host cells. Secondly, we addressed key aspects in the END-TB strategy to circumvent the limitations of current TB diagnostic tools showing the potential of CD38-based TAM-TB assay as a promising non-sputum diagnostic test that can be implemented in the field and routinely deliver accurate results with a 24h turnaround time
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Etude du rôle des polykétides mycobactériens dans la biogénèse de l'enveloppe et la virulence des mycobactéries : caractérisation de l'étape de condensation des acides mycoliques
Get PDFCertaines mycobactéries sont responsables à l'heure actuelle et depuis l'antiquité de pathologies infectieuses graves comme la tuberculose, résultante d'une infection par Mycobacterium tuberculosis. En dépit d'une médecine efficace liée à l'avènement des antibiotiques, cette infection bactérienne est à l'échelle mondiale, la première cause de mortalité due à un agent infectieux. Deux millions de décès seraient annuellement liés à cette pathologie selon les données de l'organisation mondiale de la santé (OMS, 2002). La tuberculose est un véritable fléau dans la majorité des pays en voie de développement où son endémie corrèle celle liée à l'épidémie du VIH, et le nombre de tuberculeux recensé en Europe comme dans d'autres pays développés reste non négligeable. La pathogénie du bacille tuberculeux laisse apparaître un équilibre quasi-parasitique avec un tiers de la population mondiale infectée. L'apparition de souches multi-résistantes aux chimiothérapies actuelles inquiète le milieu médical en réduisant le nombre de médicaments disponibles. Une stratégie de prise en charge mondiale par l'OMS a récemment été adoptée pour tenter d'endiguer l'épidémie de tuberculose. En parallèle, des efforts en recherche fondamentale et clinique sont entrepris afin de décortiquer la pathogénie du bacille tuberculeux pour mieux le combattre. Dans cet objectif, le séquençage récent de son génome a représenté une avancée majeure. Il dévoile notamment 250 gènes relatifs à la biosynthèse lipidique, soit cinq fois plus que chez E.coli, dont 24 coderaient des polykétides synthases (Pks). Ces enzymes sont sources de molécules complexes souvent biologiquement actives, dont la toxine de Mycobacterium ulcerans, la mycolactone, est particulièrement représentative chez les mycobactéries. Récemment, nombre de produits de polykétides synthases se sont révélés être des composantes de l'enveloppe de Mycobacterium tuberculosis. Cette enveloppe représente une arme remarquable pour le bacille tuberculeux tant par la barrière d'imperméabilité qu'elle constitue que par ses propriétés immunologiques vraisemblablement impliquées dans sa résistance à l'immunité de l'hôte. L'approche génétique abordée dans ce travail a permis d'évaluer la contribution des différents polykétides mycobactériens dans la virulence de M.bovis BCG et M.tuberculosis en modèle murin. De plus, nous avons pu caractériser la fonction d'un locus comprenant la polykétide synthase 13 ainsi qu'une acyl-AMP synthase et une acyl-coA carboxylase dans la dernière étape de la biosynthèse des acides mycoliques, lipides majeurs de l'enveloppe mycobactérienne et essentiels pour la survie des mycobactéries. Ainsi, les enzymes caractérisées dans ce travail constituent des cibles de choix pour le développement de nouveaux antituberculeux.Since the antiquity, mycobacteria have been involved in lethal pathology such as leprosy or tuberculosis, the latter caused by Mycobacterium tuberculosis and the former by Mycobacterium leprae. Despite modern medicine including antibiotics, tuberculosis keep on being the first cause of mortality due to a single infectious agent with an average of two millions deaths per year, according to the world health organisation (WHO, 2002). Tuberculosis is a real plague in the majority of developping countries where its endemy correlates those of the HIV epidemy. Furthermore the number of tuberculosis patient number in Europe as well as in other developping countries is still not negligible. Moreover, the emergence of strains resistant to the currently used antibiotics is worrying the medical profession by reducing avalaible active molecules. Without the huge mortality associated with tuberculosis, this disease would be considered as a parasitic infection regarding the estimated number of infected but asymptomatic people (around 33% of the world population). Recently, the WHO has initiated a global approach to control the epidemy. In parallel, efforts in fondamental and clinical investigation are ongoing to understand tuberculosis pathogeny and to developp new clinical tools. Recently, the entire genome of M.tuberculosis was sequenced. It revealed 250 genes related to lipid biosynthesis, which represents a considerable involvment regarding the approximativly 50 genes found in E.coli genome. Remarkably 24 of this 250 genes encode polyketide synthase (Pks). In other bacteria, these enzymes are known to produce complex molecules with pharmaceutical interest. In mycobacteria, the mycolactone, is a potent toxin produced by Mycobacterium ulcerans. Recently, numerous polyketides has been shown to be components of the M.tuberculosis envelop. This envelop represents a powerfull weapon for the tuberculous bacillus constituting a permeability barrier and delivering immunological advantages. The genetic approach used in this work allowed us to evaluate the contribution of the various polyketides in the virulence of M.bovis BCG and M.tuberculosis in a mouse model. Furthermore, we caracterised the fonction of the locus including the polyketide synthase 13, an acyl-AMP synthase and an acyl-coA carboxylase in the last step of mycolic acid biosynthesis. Mycolic acids are major constituent of the mycobacterial cell envelop and are essential for mycobacterial viability, therefore the enzymes caracterised in the second part of this work constitutes promising targets for developping new antituberculous drugs
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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