1,720,977 research outputs found
Tubular bioartificial organs : from physiological requirements to fabrication processes and resulting properties : a critical review
Full text linkIn this featured review manuscript, the aim is to present a critical survey on the processes available for fabricating bioartificial organs (BAOs). The focus will be on hollow tubular organs for the transport of anabolites and catabolites, i.e., vessels, trachea, esophagus, ureter and urethra, and intestine. First, the anatomic hierarchical structures of tubular organs, as well as their principal physiological functions, will be presented, as this constitutes the mandatory requirements for effectively designing and developing physiologically relevant BAOs. Second, 3D bioprinting, solution electrospinning, and melt electrowriting will be introduced, together with their capacity to match the requirements imposed by designing scaffolds compatible with the anatomical and physiologically relevant environment. Finally, the intrinsic correlation between processes, materials, and cells will be critically discussed, and directives defining the strengths, weaknesses, and opportunities offered by each process will be proposed for assisting bioengineers in the selection of the appropriate process for the target BAO and its specific required functions
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
Design, development and validation of tubular constructs for regenerative medicine
No full textLes lésions, les maladies et les dysfonctionnements des organes tubulaires représentent un défi unique pour les bio-ingénieurs et les cliniciens. Une approche multidisciplinaire doit être appliquée pour réussir à développer des organes fonctionnels issus de l'ingénierie tissulaire (TE). Dans la recherche actuelle concernant la fabrication d'organes tubulaires fonctionnels, il manque un lien qui se concentre sur la corrélation entre (i) les exigences mécaniques et biologiques de la conception de l'échafaudage dictées par la structure anatomique et les fonctions physiologiques, (ii) le processus de fabrication (y compris la sélection des matériaux et la technique de traitement) et (iii) les propriétés mécaniques et biologiques résultantes de l'organe tubulaire TE développé. Par conséquent, le présent doctorat vise à relever certains des défis actuellement rencontrés dans l'ingénierie tissulaire et la médecine régénérative, et plus particulièrement dans la réparation des tendons et la modélisation des parois vasculaires. À cette fin, des biomatériaux spécifiques ont été conçus et caractérisés, et de multiples techniques de fabrication des biomatériaux ont été évaluées. Dans une première partie de cette thèse, des nouveaux polymères polyvalents photoréticulables à base d'uréthane (AUP) ont été développés, ainsi que leur mise en œuvre comme matériaux de départ pour le développement d'échafaudages tubulaires. Parce que chaque tissu a ses propres exigences mécaniques et biologiques, et parce que chaque technique de traitement a ses propres défis spécifiques, une boîte à outils de AUPs a été proposée. Des AUPs basés sur un backbone de poly(éthylène glycol) (PEG) et un backbone de poly(ε-caprolactone) (PCL) avec différentes masses molaires ont été synthétisés. Les AUPs ont montré une large gamme de propriétés physiques et mécaniques, couvrant les propriétés de nombreux tissus et les rendant idéales pour la médecine régénérative d'un point de vue mécanique. En outre, les AUPs développés ont permis une réticulation UV efficace à l'état solide, ouvrant la voie à diverses possibilités de techniques de fabrication, notamment l'électrospinning en solution (SES), l'impression 3D par extrusion (3DP) et l'électrowriting en fusion (MEW). Une des possibilités de technique de fabrication mentionnées ci-dessus se trouve dans le MEW. Actuellement, l'un des défis associés à l'utilisation du MEW est la disponibilité limitée de matériaux compatibles. Par conséquent, dans cette thèse de doctorat, la MEW a été étudiée en tant que technique de fabrication émergente pour transformer les AUPs développés en constructions tubulaires avec une architecture prédéfinie et présentant des propriétés mécaniques réglables. Une deuxième technique de fabrication choisie pour évaluer le potentiel des AUP développés est le SES. L'une des applications biomédicales possibles des constructions tubulaires en médecine régénérative est la réparation des tendons. Afin de surmonter les défis actuellement rencontrés dans la réparation des tendons, une combinaison d'une approche mécanique (par la conception du matériau et de l'échafaudage) et biologique (par des médicaments anti-adhésion et anti-inflammatoires) a été proposée dans cette thèse. Une autre application possible des constructions tubulaires en médecine régénérative peut être trouvée dans le domaine de la TE vasculaire. Dans cette thèse, l'utilisation d'un échafaudage synthétique tubulaire comme renfort pour des modèles à base de collagène a été exploitée dans le but d'obtenir les propriétés mécaniques requises pour la modélisation de la paroi vasculaire. Trois techniques de fabrications différentes (SES, 3DP et MEW) ont été évaluées pour le développement du renfort tubulaire en polymère. Outre l'utilisation d'un échafaudage de renforcement synthétique pour obtenir des propriétés mécaniques supérieures dans les modèles de parois vasculaires à base de collagène, une autre approche consiste à maintenir l'intégrité structurelle des échafaudages par réticulation chimique, physique ou enzymatique. Par conséquent, dans la deuxième partie de cette thèse, un collagène photoréticulable aux propriétés ajustables a été développé et comparé à l'étalon-or de la TE, à savoir la gélatine modifiée par le méthacrylamide. La distribution de fragments photoréticulables sur un squelette protéique peut affecter le comportement de réticulation d'un biomatériau, et donc aussi ses propriétés mécaniques et biologiques. Une connaissance approfondie à cet égard est essentielle pour les biomatériaux exploités dans l'ingénierie tissulaire et la médecine régénérative, afin de permettre la transposition de nouveaux biomatériaux fonctionnalisés du laboratoire au chevet du patient, compte tenu des contraintes réglementaires. C'est pourquoi l'analyse protéomique a été évaluée comme un outil permettant de mieux comprendre les modifications des biopolymères photoréticulables. Les recherches menées dans le cadre de cette thèse ont permis d'élargir la variété de biomatériaux, mais ont également permis de mieux comprendre certaines exigences critiques concernant la conception des biomatériaux, la technique de fabrication ainsi que les propriétés mécaniques et biologiques de l'échafaudage.Injury, diseases and malfunctioning of tubular organs represent a unique challenge for bioengineers and clinicians. A multidisciplinary approach needs to be applied to successfully develop functional tissue engineered (TE) organs. In the current research regarding the regeneration of functional tubular organs, there is a missing link that focuses on the correlation between (i) the mechanical and biological requirements of the scaffold design dictated by the anatomical structure and physiological functions, (ii) the fabrication process (including material selection and processing technique) and (iii) the resulting mechanical and biological properties of the developed tubular TE organ. Therefore, the current PhD focuses on addressing some of the challenges currently encountered in tissue engineering and regenerative medicine, and more specifically, in tendon repair and vascular wall modeling. To this end, specific biomaterials were designed and characterized, and multiple biomaterial processing techniques were evaluated. In a first part of this PhD thesis, novel versatile photo-crosslinkable urethane-based polymers (AUPs) were developed, along with their implementation as starting materials for the development of tubular scaffolds. Because each tissue has its own mechanical and biological requirements, and because each processing technique has its own specific challenges, a toolbox of AUPs was proposed, taken into account the challenges and requirements while synthesizing and formulating the AUPs. AUPs based on a poly(ethylene glycol) (PEG) backbone versus a poly(ε-caprolactone) (PCL) backbone with different molar masses were synthesized (i.e. AUP PEG2k, 20k; AUP PCL530, 2k, 10k and 20k). The developed PEG- and PCL-based AUPs showed a broad range in physical and mechanical properties, covering the properties of many tissues and rendering them ideal for regenerative medicine from a mechanical perspective. Moreover, the developed AUPs enabled efficient UV-crosslinking in the solid state, paving the way towards various processing opportunities, including solution electrospinning (SES), extrusion-based 3D printing (3DP) and melt electrowriting (MEW). One of the above-mentioned processing opportunities can be found in MEW. At present, one of the challenges associated with the use of MEW is the limited availability of compatible materials. Therefore, in this PhD thesis, MEW was investigated as an emerging fabrication technique to process the developed AUPs into tubular constructs with a predefined architecture and exhibiting tunable mechanical properties. A second processing technique that was selected to evaluate the processing potential of the developed AUPs is SES. One possible biomedical application of tubular constructs in regenerative medicine can be found in tendon repair. In order to overcome the challenges currently encountered in tendon repair (i.e. insufficient mechanical properties along with adhesion and inflammatory issues), a combination of a mechanical (by material and scaffold design) and biological approach (by anti-adhesion and anti-inflammatory drugs) was proposed in this PhD thesis. Another possible application of tubular constructs in regenerative medicine can be found in the field of vascular TE. In this PhD thesis, the use of a tubular, synthetic scaffold as reinforcement for collagen-based models was exploited with the aim to achieve the required mechanical properties for vascular wall modeling. Three different processing techniques (i.e. SES, 3DP, and MEW) were evaluated for the development of the tubular, polymeric reinforcement. Apart from using a synthetic reinforcement scaffold to achieve superior mechanical properties in collagen-based vascular wall models, another approach includes maintaining the scaffolds's structural integrity by chemical, physical or enzymatic crosslinking. Therefore, in a second part in this PhD thesis, a photo-crosslinkable collagen (COL-MA) with tunable properties was developed and benchmarked against the gold standard in TE, being methacrylamide-modified gelatin (GEL-MA). The distribution of photo-crosslinkable moieties onto a protein backbone can affect a biomaterial's crosslinking behavior, and therefore also its mechanical and biological properties. A profound insight in this respect is essential for biomaterials exploited in tissue engineering and regenerative medicine to enable translation of novel, functionalized biomaterials from bench to bedside, given regulatory constraints and the need for perfectly defined and reproducible biomaterials. Therefore, proteomic analysis was evaluated as a tool to gain next level insights in photo-crosslinkable biopolymer modifications. The research conducted in this PhD thesis resulted in the expansion of the biomaterial portfolio, but also provided greater insight into some critical requirements regarding biomaterial design, the fabrication process, and the scaffold's resulting mechanical and biological properties
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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