1,721,115 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
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
sRNA and Enterococcus faecium pathogenesis
No full textEnterococcus faecium est une bactérie commensale du tube digestif de l’homme, pathogène opportuniste multi-résistant aux antibiotiques et responsable d’épidémies hospitalières. L’existence d’ARN régulateurs chez E. faecium (Ern) ayant récemment été découverte, ce travail de thèse avait pour objectif d’évaluer leur implication in vivo. Un modèle de colonisation a été mis au point chez la souris, à partir de plusieurs modèles décrits dans la littérature. Ils ont été comparés, et un nouveau modèle associant la ceftriaxone et l’amoxicilline a été développé. L’ARN régulateur Ern0160 a ensuite été étudié. Quatre souches d’E. faecium ont été utilisées, Aus0004 (WT), la souche mutante WT délétée d‘ern0160 (Δ0160), la souche Δ0160 trans-complémentée surexprimant ern0160 (Δ0160_0160), et la souche Δ0160 contenant le vecteur pAT29 vide (Δ0160_pAT29). Dans les expériences in vitro, aucune différence n'a été observée entre les souches WT et Δ0160 cultivées seules, tandis que la souche Δ0160_0160 s'est développée plus lentement que Δ0160_pAT29. In vivo, aucune différence significative de colonisation n’a été observée avec les souches inoculées seules. Dans les essais de compétition in vitro et in vivo, la souche WT était prédominante par rapport à la souche délétée Δ0160. Avec la suspension « Δ0160_0160 + Δ0160_pAT29 », la souche Δ0160_pAT29 était prédominante, suggérant un effet délétère de la surexpression d’ern016. Ces résultats suggèrent l'implication d'Ern0160 dans la colonisation intestinale par E. faecium. Des modèles d’infection (endocardite infectieuse et bactériémie secondaire à une translocation intestinale) ont été développés au cours de ce travail mais restent à finaliser.Enterococcus faecium is a normal inhabitant of the human gut intestinal tract (GIT) and an opportunistic pathogen multi-resistant to antibiotics and responsible for hospital outbreaks. Since the existence of regulatory RNAs in E. faecium (Ern) has been recently discovered, the aim of this study was to evaluate their involvement in vivo. A murine GIT colonization model was developed, based on several published models thatwere compared, and a new one combining ceftriaxone and amoxicillin was developed. Then, the regulatory RNA Ern0160 was studied. Four E. faecium strains were used, Aus0004 (WT), an ern0160-deleted Aus0004 mutant (Δ0160), a trans-complemented Δ0160 strain overexpressing ern0160 (Δ0160_0160), and a strain Δ0160 with an empty pAT29 vector (Δ0160_pAT29). In in vitro experiments, no difference was observed between WT and Δ0160 strains cultured individually while Δ0160_0160 strain grew more slowly than Δ0160_pAT29. In competitive assays, the WT strain was predominant compared to the deleted strain Δ0160 at the end of the experiment. A GIT colonization was performed with each strain alone and no significant difference was noticed. By contrast, significant results were obtained with co-colonization experiments. With WT + Δ0160 suspension, a significant advantage for the WT strain was observed, suggesting the involvement of ern0160 in GIT colonization. With Δ0160_0160 + Δ0160_pAT29 suspension, the strain with the empty vector took the advantage from day 3 to the end of the protocol, suggesting a deleterious effect of ern0160 overexpression. Altogether, these findings demonstrate the potential implication of Ern0160 in GIT colonization of E. faecium. Infection models have also been developed during this work but remain to be finalized
Variability factors of beta-lactam concentration-effect relationship in infective endocarditis
No full textLe suivi thérapeutique pharmacologique (STP) des bêta-lactamines permet l’individualisation de la prise en charge d'infections profondes comme l’endocardite infectieuse (EI). La faible diffusion supposée au site infectieux, à savoir les valves cardiaques, est un des éléments qui justifie leur administration à forte dose par voie intra-veineuse. Ainsi, les patients atteints d’EI se voient donc exposés à de fortes concentrations bêta-lactamines pendant 2 à 6 semaines. Dans ce contexte, la survenue d’une neurotoxicité ou d’une néphrotoxicité aux bêta-lactamines peut être lourde de conséquences. Or il existe peu de données de diffusion des bêta-lactamines dans les valves cardiaques et le lien concentration-neurotoxicité des bêta-lactamines est mal documenté en particulier pour l’amoxicilline. Enfin, dans un contexte d’augmentation de l’incidence des EI staphylococciques, la réponse microbiologique aux antibiotiques dans la prise en charge de l’EI à S. aureus est elle-même mal décrite et nécessite d’être évaluée en condition biofilm. Ainsi, la première partie de ce travail a permis d’identifier un seuil de concentrations neurotoxiques en amoxicilline par l’exploitation d’un entrepôt de données intra-hospitalières. La deuxième partie du travail a permis de caractériser au sein d’un essai prospectif une diffusion conséquente des bêta-lactamines au sein des valves cardiaques, en particulier de l’amoxicilline avec un ratio diffusion médian plasma:valve de 62%. Enfin la mise au point d’un modèle ex vivo d’EI à S. aureus sur valves humaines a permis la comparaison de l’activité anti-biofilm de la vancomycine,et d’un lipoglycopeptide; la dalbavancine et d’identifier une activité éradicatrice du biofilm marquée pour cette dernière, fournissant un élément supplémentaire de l’acitivé de la dalbavancine dans l’EI. L’ensemble de ces données a permis d’affiner la fenêtre thérapeutique des anti-infectieux indiqués dans la prise en charge de l’endocardite.Beta-lactam therapeutic drug monitoring (TdM) is routinely performed, particularly in the management of deep infections such as infective endocarditis (IE). Diffusion to the site of infection, i.e. the heart valves, is supposed to be low, justifying high-doses intravenous administration. Thus, patients are exposed to high concentrations for 2-6 weeks. In this context, the onset of beta-lactam neurotoxicity or nephrotoxicity may have serious consequences. However, there is poor knowledge about the diffusion of beta-lactams in the heart valves and their concentration-neurotoxicity relationship, especially for amoxicillin. Finally, in a context of increasing incidence of staphylococcal IE, the microbiological response to antibiotics in S. aureus IE is itself poorly described and needs to be assessed in biofilm growing conditions. Thus, the first part of this work identifed a threshold of neurotoxic concentrations of amoxicillin using our hospital data warehouse. The second part of this work characterised in a prospective trial a consequent diffusion rate of beta-lactams within the heart valves, in particular for amoxicillin with a median plasma:valve diffusion ratio of 62%. Finally, the implementation of an ex vivo model of S. aureus IE on human valves confirmed the antibiofilm activity of penicillin M currently used on methicillin-sensitive strains. The comparison of the anti-biofilm activity of vancomycin, currently recommended for methicillin-resistant S. aureus strains, and a new lipoglycopeptide, dalbavancin, identified a marked biofilm-eradicating activity for the latter, provinding an additional evidence of dalbavancin activity in IE
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
Evaluation du traitement antibiotique des infections de prothèse vasculaire à Staphylococcus aureus : apport d'un modèle murin
Full text linkProsthetic vascular graft infection (PVGI) is an emerging disease, mostly due to staphylococci, with limited data regarding efficacy of current antistaphylococcal agents. We aimed to assess the efficacy of different antibiotic regimens. Six different strains of methicillin-susceptible (MSSA) and methicillin-resistant S. aureus (MRSA) were used. We compared results of minimal biofilm inhibitory and eradicating concentrations (MBICs and MBECs) obtained with a Calgary Biofilm Pin lid Device (CBPD) to those yielded by an original Dacron®-related minimal inhibitory and eradicating concentrations measure model. We then used an original murine model of Staphylococcus aureus vascular material infection to evaluate efficacy of different antibiotic regimens. We finally visualized the effect of antibiotics on biofilm by confocal microscopy. We demonstrated that classical measures of MBICs and MBECs with CPBD could overestimate the decrease of antibiotic susceptibility in material related infections and that the nature of the support used to measure biofilm susceptibility might be influent since results yielded by our Dacron®-related minimal eradicating assay were lower than those found on a plastic device. In our in vivo model, we shown that daptomycin was significantly more bactericidal than comparators for some strains of MRSA or MSSA but not for all. For the majority of strains, it was as efficient as comparators. The addition of rifampicin to daptomycin did not enhance daptomycin efficacy in our model. Finally, we highlighted an in vivo differential effect on biofilm depending on the antibiotic used but also on the bacterial strain evaluated. Our models represent an option to better define the best antibiotic options for PVGIs.Les infections de prothèses vasculaires (IPV) sont des maladies particulièrement graves. Malgré une fréquence finalement assez importante, elles demeurent mal connues. Staphylococcus aureus en est l’agent responsable principal. Les données concernant le traitement antibiotique à administrer pour ces infections sont excessivement pauvres. L’objectif de notre travail était donc de comparer l’efficacité de différents protocoles d’antibiothérapie à l’aide de divers modèles expérimentaux d’IPV. Six souches différentes de S. aureus ont été évaluées : 3 sensibles (SAMS) et 3 résistants à la méticilline (SARM). Nous avons comparé les concentrations minimales inhibitrices et éradicatrices (CMIB et CMEB) au sein du biofilm obtenues avec des techniques classiques sur polystyrène à ceux obtenus à l’aide d’un modèle original in vitro sur Dacron® (dCMIB et dCMEB) ®. Nous avons ensuite utilisé un modèle original d’infection de Dacron chez la souris pour comparer l’efficacité de différents protocoles thérapeutiques. Enfin nous avons visualisé l’effet de ces antibiotiques in vivo par microscopie confocale. Nous avons montré que les mesures classiques de CMIB et CMEB obtenues sur polystyrène pouvaient surestimer la baisse d’efficacité des antibiotiques dans le biofilm et que des mesures sur le matériel d’intérêt pouvaient être plus pertinentes. Dans notre modèle in vivo, la daptomycine pouvait être supérieure que les comparateurs pour certaines souches de SARM et de SAMS mais pas pour toutes. Par contre, si l’ajout de rifampicine était bénéfique pour la cloxacilline et la vancomycine, cela n’était pas le cas pour la daptomycine. Enfin, nous avons visualisés des effets totalement différents sur le biofilm selon les antibiotiques utilisés mais également selon les souches testées. Nos modèles ont permis d’obtenir des informations nouvelles concernant l’antibiothérapie des IPV qui, nous l’espérons, permettront d’aider à la prise en charge des patients
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