1,721,039 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
A molecular delivery system for the in situ production of glucose in a tissue engineering hydrogel
No full textEn ingénierie tissulaire, la survie in vivo de cellules souches implantées au sein d’un biomatériau est limitée par les conditions d’un environnement ischémique qui se caractérise par un déficit en oxygène et en nutriments. Récemment, dans le cadre d’un projet de recherche dédié au développement d’un hydrogel composite à base de fibrine, biomatériau conçu pour améliorer la survie de cellules souches post-implantation, il a été mis en évidence la nécessité de contrôler dans le temps et l’espace la disponibilité du glucose au sein de ce matériau. Cet apport in situ de glucose est réalisé par dégradation contrôlée de l’amidon, un polymère de glucose. Cette production est assurée par action enzymatique d’un catalyseur spécifique de l’hydrolyse de l’amidon, l’amyloglucosidase (AMG).Toutefois, il convient de maitriser différents paramètres tels que la fuite de l’AMG en dehors de l’hydrogel ou encore sa perte d’activité au cours du temps. Dans ce contexte, l’encapsulation de l’AMG dans des nanoparticules d’un polymère biodégradable et biocompatible, ici l’acide poly(lactique-co-glycolique) (PLGA), devrait permettre le contrôle des paramètres susmentionnés.Des nanoparticules de type core-shell contenant l’AMG (NPe) ont été synthétisés par l’adaptation d’un protocole de double émulsion (water-oil-water). Différentes méthodes ont été développées pour déterminer les propriétés physico-chimiques et biochimiques des nanoparticules produites. Le protocole de synthèse a été optimisé afin de produire des nanoparticules reproductibles et stériles utilisables dans des hydrogels implantables in vivo.Le cahier des charges de l’hydrogel enrichi en amidon et en NPe impose un apport continu du glucose pendant 1 mois. La stabilité des nanoparticules a été étudiée en solution et dans les hydrogels. La production de glucose grâce à ces NPe a été investiguée en solution et en hydrogel mettant en avant l’intérêt de ces nanoparticules au sein du dispositif.In tissue engineering, the in vivo survival of stem cells located within a biomaterial is limited by an ischemic environment characterized by a low supply of oxygen and nutrients. Recent studies on fibrin based hydrogels (designed to improve stem cells survival after implantation) have highlighted the need to control the spatiotemporal availability of glucose within a biomaterial scaffold. Glucose release occurs through the degradation of starch, a glucose polymer, at a rate controlled by the action of the enzyme amyloglucosidase (AMG), a specific catalyst for the hydrolysis of starch.In order to eventually be of clinical impact, critical parameters must be tuned, such as the AMG leakage outside the hydrogel and its loss of activity over time. In this context, AMG encapsulation within nanoparticles of a biodegradable and biocompatible polymer, here poly(lactic-co-glycolic acid) (PLGA), is a promising means toward controlling the above parameters.The AMG-containing core-shell type nanoparticles (NPe) were synthesized by an adaptation of the double emulsion technique (water-oil-water). Different methods have been developed to determine the physicochemical and biochemical properties of the resulting nanoparticles. The synthesis was optimized to produce sterile and reproducible nanoparticles appropriate for in vivo implantable hydrogels.Nanoparticle stability and glucose release were investigated in solution and in hydrogels. A key specification of the hydrogel system, enriched in starch and NPe, is the continuous supply of glucose over 1 month. Glucose production was observed to meet this specification, highlighting the potential advantages of this approach
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
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
Development of calcium alginate dressings with antibiofilm activity
No full textLa prévention et le soin des plaies représente un enjeu majeur de santé publique. Cela est vrai notamment dans les contextes où s’installent un biofilm bactérien spécifique qui souvent compromet le processus de cicatrisation via l’acquisition par les bactéries de formes de vie qui leur confèrent entre autres une tolérance accrue aux antibiotiques et une virulence plus forte. La présence de biofilm dans les plaies conduit dans ces dernières à un maintien d’un état inflammatoire chronique qui compromet la cicatrisation de la peau lésée.Définir et trouver des stratégies pour prévenir et lutter contre le biofilm dans les plaies est un véritable challenge de santé publique. C’est l’enjeu principal du projet ABC décliné à travers le développement d’une compresse d’alginate de calcium à activité antibiofilm.Dans ce cadre, trois actifs naturels pertinents ont d’abord été sélectionnés (l’acide gallique, le carvacrol et la curcumine) et ont permis le développement de solutions qui ont su démontrer des propriétés inhibitrice et/ou bactéricide sur S. aureus et P. aeruginosa, les deux espèces bactériennes les plus communément retrouvées dans les plaies. Les solutions d’acide gallique et de carvacrol ont également montré des propriétés antibiofilm puisqu’elles amènent au minimum à une diminution de la biomasse bactérienne de plus de 5log sur P. aeruginosa et S. aureus. La combinaison de ces deux actifs en solution a permis l’obtention d’un effet antibiofilm sur les deux types de biofilm ainsi que sur un biofilm double-espèces de S. aureus et P. aeruginosa.Fort de ces résultats, des prototypes de compresses ont été développés avec la mise en place d’une méthode de production. Elle comprend une étape d’imprégnation, de séchage et de stérilisation ainsi que des points de contrôles pour évaluer l’efficacité du séchage ou encore la quantité d’actifs présents dans les compresses. Cette méthode de production permet d’aboutir à des compresses enrichies en actifs. Celles contenant un seul actif permettent un effet antibiofilm sur S. aureus tandis que des compresses avec une combinaison du carvacrol et de l’acide gallique ou de la curcumine permettent d’obtenir un effet antibiofilm aussi sur P. aeruginosa. Toutefois la stabilité des actifs au cours du temps a dû être optimisée.Afin de stabiliser les actifs, une optimisation de la formulation a été réalisée au travers de l’encapsulation des molécules dans des cyclodextrines. Il a ainsi été possible de complexer le carvacrol et l’acide gallique avec la beta-cyclodextrine et l’hydroxypropyl-beta-cyclodextrine. Les différents complexes ont été caractérisés ce qui a permis de comprendre une partie des interactions mises en place entre actifs et cyclodextrines et de démontrer une bonne stabilité des actifs complexés au cours du temps. Sous cette formulation l’acide gallique ne présente plus d’activité antibiofilm mais à l’inverse l’efficacité antibiofilm du carvacrol est conservée sur S. aureus. La formulation reste encore à optimiser et des expériences complémentaires doivent être réalisées pour trouver les paramètres adéquats permettant une activité antibiofilm des deux actifs encapsulés.Wounds prevention and care is a major public health issue. This is particularly true in contexts where a specific bacterial biofilm is established, which often compromises the healing process through the acquisition by bacteria of life forms that give them, among other things, increased tolerance to antibiotics and greater virulence. Biofilm presence in wounds leads to the maintenance of a chronic inflammatory state in wounds compromising the healing of injured skin.Defining and finding strategies to prevent and fight against biofilm in wounds is a real public health issue. This is the main challenge of the ABC project, which involves the development of a calcium alginate dressing with antibiofilm activity.In this context, three relevant natural active ingredients were first selected (gallic acid, carvacrol and curcumin) and allowed the development of solutions that demonstrated inhibitory and/or bactericidal properties on S. aureus and P. aeruginosa, the two bacterial species most commonly found in wounds. Solutions of gallic acid and carvacrol have also shown antibiofilm properties as they lead to a minimum decrease in bacterial biomass of more than 5log on P. aeruginosa and S. aureus. The combination of these two active ingredients in solution allowed an antibiofilm effect to be obtained on both types of biofilm as well as on a double species biofilm of S. aureus and P. aeruginosa.Based on these results, dressings prototype were developed with the implementation of a production method. It includes impregnation, drying and sterilisation stages as well as control points to evaluate the effectiveness of the drying or the quantity of active ingredients present in dressings. This production method results in active-enriched compresses. Those containing a single active ingredient allow an antibiofilm effect on S. aureus, while dressings with a combination of carvacrol and gallic acid or curcumin allow an antibiofilm effect also on P. aeruginosa. However, the stability of the actives over time had to be optimised.In order to stabilise the active ingredients, the formulation was optimised by encapsulating molecules in cyclodextrins. It was thus possible to complex carvacrol and gallic acid with beta-cyclodextrin and hydroxypropyl-beta-cyclodextrin. The different complexes were characterised, which made it possible to understand some of the interactions between the active ingredients and cyclodextrins and to demonstrate good stability of the complexed active ingredients over time. Under this formulation, gallic acid no longer exhibits antibiofilm activity, but conversely, the antibiofilm efficiency of carvacrol is retained on S. aureus. The formulation still needs to be optimised and further experiments need to be carried out to find the right parameters for the antibiofilm activity of both encapsulated actives
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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