1,721,055 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
Purification and functionalization of single-walled carbon nanotube samples : efficiency and selectivity of the chemical treatments
No full textLa mise en évidence des nanotubes de carbone mono-feuillets (SWCNTs) en 1993 par S. Iijima a été une des découvertes qui a marqué la recherche dans le domaine des nanos. L'étude de leurs propriétés a révélé qu'elles étaient supérieures à celles de matériaux déjà connus et a laissé entrevoir un champ très large d'applications potentielles. Les méthodes de synthèse actuelles permettent de produire des SWCNTs en grande quantité. Cependant, les échantillons de SWCNTs peuvent être hétérogènes tant au niveau de leur composition (impuretés carbonées et métaux catalytiques) qu'en ce qui concerne les caractéristiques des SWCNTs eux-mêmes. Des traitements post-synthèses sont donc indispensables pour améliorer les caractéristiques des échantillons. Dans ce travail, nous avons dans un premier temps mis en oeuvre une procédure de purification (multi-étape) couramment utilisée. En accord avec la littérature, l'optimisation des paramètres expérimentaux notamment en ce qui concerne le traitement d'oxydation n'a pas permis d'obtenir de bons rendements de purification et une sélectivité de réaction performante. Une méthode de purification alternative a été développée. Elle consiste essentiellement à un traitement thermique sous flux de dichlore. Elle a permis de diminuer significativement la proportion d'impuretés métalliques tout en préservant les nanotubes. Elle s'est également révélée efficace avec des échantillons produits selon différentes méthodes. L'autre difficulté majeure dans l'utilisation des nanotubes est leur processabilité. La modification de l'état de surface des nanotubes passe par la fonctionnalisation chimique. Pour cela, nous avons étudié le greffage de fonctions sondesThe discovery of single-walled carbon nanotubes (SWCNTs) in 1993 by S. Iijima has been one of the milestones of scientific research in the domain of nanos. The study of their properties has revealed that they were superior to those of materials already known and has let to foresee a field of numerous potential applications. The actual methods of synthesis enable to produce SWCNTs in large quantities. However, the SWCNT samples can be heterogeneous regarding both their composition (carbonaceous and metal impurities) and the features of the as-produced SWCNTs. Post-synthesis treatments are therefore indispensable to improve the characteristics of the samples. In this work, firstly we have carried out a standard multi-step purification procedure. In agreement with literature, the optimization of experimental parameters notably those used for the oxidation treatment did not permit us to obtain neither good yields of purification nor efficient selectivity of reaction. An alternative purification method has thus been developed. It consists mainly in a thermal treatment under a dichlore stream. It has enabled to significantly decrease the proportion of metallic impurities in the samples while preserving the nanotubes. It has also shown that this new purification process was efficient with samples produced by different methods. The other main difficulty in using nanotubes is their processability. Chemical functionalization is then needed to modify nanotube surface properties. In that case, we have studied the grafting of probe function
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
Fonctionnalisation chimique des nanomateriaux carbonés (nanotubes de carbone et graphène) : importance du compromis surface-structure
No full textLes nanotubes de carbone et le graphène ont un grand potentiel d'application dans de nombreux domaines. En raison de leur structure sp2, les deux nanomatériaux sont difficiles à disperser dans la plupart des solvants, ce qui constitue un défi à relever pour leur intégration dans des matériaux. La fonctionnalisation non covalente et covalente permet d'améliorer la dispersibilité de ces matériaux. La première approche est simple et nécessite un additif : une molécule tensioactive. L'approche covalente implique un endommagement du réseau sp2 de ces nanomatériaux carbonés et peut conduire à une diminution de leurs propriétés physiques si cette modification structurale n'est pas bien contrôlée. Comprendre les mécanismes et les paramètres pertinents lorsque la fonctionnalisation est utilisée est fondamental dans ce domaine et c'est encore un sujet de débat dans la littérature. Ce travail de doctorat propose une nouvelle approche pour mieux comprendre la fonctionnalisation covalente en appliquant trois traitements covalents différents à deux types différents de nanotubes de carbone et de graphènes. Les résultats obtenus ont permis de déterminer les paramètres influençant la fonctionnalisation de ces nanomatériaux carbonés. En particulier, les défauts natifs jouent un rôle crucial pour induire le greffage de groupes fonctionnels sur les nanomatériaux de carbone utilisés. Et la sélectivité de fonctionnalisation d'un traitement donné est remise en question à partir des résultats obtenus. La deuxième partie du travail concerne la préparation de dispersions stables de ces nanomatériaux carbonés dans différents solvants pour leur intégration facile dans trois structures macroscopiques : nanofluides, composites et hybrides. Dans le cas des nanofluides, en modulant la force de fonctionnalisation covalente appliquée, il a été possible de préserver la conductivité thermique du nanofluide et d'obtenir une bonne stabilité de dispersion dans le temps. Une comparaison entre les nanofluides à base de nanotubes de carbone modifiés de manière covalente et ceux basés sur une modification non covalente révèle que la fonctionnalisation covalente est préférée lorsque la température augmente. Nous avons réussi à obtenir un composite homogène nanomatériau de carbone-cuivre par co-électrodéposition en utilisant l'approche non covalente. Et l'assemblage macroscopique de nanotubes de carbone sous forme de films a pu servir de substrat pour préparer des hybrides carbone-inorganique.Carbon nanotubes and graphene are foreseen to find use in many applications in the near future. Due to their native sp2 structure, both nanomaterials are difficult to disperse in most solvents, which is a challenge to overcome before their integration in most materials. The non-covalent and covalent functionalization allows the improve the materials dispersibility. The first approach is simple and requires the use of a foreign agent. The covalent approach involves disruption the carbon nanomaterial sp2 network and can lead to diminishing their physical properties if it is not well controlled. Understanding the mechanisms and the relevant parameters when functionalization is used is fundamental in this field and this is still a topic of debate in literature. This PhD work proposes a novel approach to better understand covalent functionalization by applying three different covalent treatments to two different types of carbon nanotubes and graphenes. The obtained results help to clarify the parameters influencing the functionalization of carbon nanomaterials. In particular, the native defects are found to play the crucial role to induce the functional group grafting to the used carbon nanomaterials. And, the functionalization selectivity of a given treatment is called into question from the obtained results. The second part of the work was focused on the preparation of stable dispersion of these carbon nanomaterial in different solvents for their facile integration in three macroscopic structures: nanofluids, composites and hybrids. In the case of nanofluids, by modulating the applied covalent functionalization force it was possible to preserve the nanofluid thermal conductivity and at the same time a good dispersion stability over time. A comparison between the covalently modified carbon nanotube based nanofluids to those based on a non-covalent modification has unveiled that covalent functionalization is preferred when temperature is increased. We have successfully obtained homogeneous carbon nanomaterial-copper composite by co-electrodeposition means using the non-covalent approach. And macroscopic assembly of carbon nanotubes under the form of films could be used as substrate to prepare carbon-inorganic hybrids
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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