1,721,012 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
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
Heterostructures, doping and surface chemistry : control of the structure and optical properties of cadmium chalcogenide nanoplatelets
No full textLes nanoplaquettes de chalcogénures de cadmium présentent des propriétés optiques uniques résultant d’une épaisseur contrôlée à l’échelle de la monocouche atomique. Elles apparaissent comme une nouvelle classe de nanomatériaux à fort potentiel applicatif. L’objectif de cette thèse est, par le design de la particule inorganique et de la chimie de surface, de faire émerger de nouvelles propriétés optiques. Dans un premier temps des hétérostructures cœur/couronne de CdSe/CdSe1-xTex ont été synthétisées et ont montré une bi-émission à l’échelle de la nanoplaquette unique. Cette bi-émission émerge d’une compétition entre la localisation de l’électron dans le cœur de CdSe induite par le décalage entre les bandes de conduction et d’une recombinaison directe dans la couronne favorisée par la grande énergie de liaison de l’exciton dans les nanoplaquettes. Des nanoplaquettes de CdSe dopées à l’argent ont été synthétisées dans un second temps. Le dopage, fait par échange cationique partiel, créé des pièges émissifs dans la largeur de bande interdite. La quantité d’argent incorporée permet un contrôle progressif de la couleur d’émission du vert au rouge grâce à la coexistence de la recombinaison de bord de bande et de l’émission liée à l’argent. Ces niveaux d’argent sont fortement liés à CdSe et se situent 340 meV au-dessus de la bande de valence du CdSe massif. Enfin, la modification de chimie de surface par un mélange de bromures et d’oleylamine diminue les contraintes de surface et améliore la passivation de surface. Ceci induit un décalage, au-delà du confinement discret, de la longueur d’onde d’émission et une augmentation du rendement quantique jusqu’à 75%.Cadmium chalcogenide nanoplatelets present unique optical properties resulting from their atomically precise thickness control. They have emerged as a new promising class of nanomaterial for optoelectronic applications. The goal of this thesis is to promote new optical properties through the design and surface chemistry of nanoplatelets. Firstly, CdSe/CdSe1-xTex core/crown heterostructures were synthesized and showed bicolor emission at the scale of a single nanoplatelet. This bicolor emission results from a competition between the localization of the electron in the CdSe core driven by the conduction band offset and the direct exciton recombination in the crown favored by the high exciton binding energy. Silver doped nanoplatelets were synthesized in the second part. This doping, performed through partial cation exchange, creates a silver-related emissive state in the band gap. The amount of silver incorporated in the nanoplatelet allows a progressive control of the emission color from green to red thanks to the coexistence of the band edge and the silver related emission. The silver state is strongly bound and is located 340 meV above the bulk valence band. Finally, the modification of the surface chemistry with bromide and oleylamine reduces the surface stresses and improves the surface passivation. This leads to a shift, beyond the discrete confinement, of the emission wavelength and increases the quantum yield up to 75 %
Synthesis and characterization of bimodal probes based on I-III-VI quantum dots for mri and nir fluorescence imaging
No full textLa chirurgie guidée par l’imagerie de fluorescence est une technique prometteuse mais limitée par la faible profondeur de pénétration (inférieure au millimètre dans le visible) à cause de l’absorption et de la diffusion par les tissus. Elle est plus élevée dans la gamme du proche infrarouge (700-1000 nm) mais reste limitée à quelques centimètres. L’imagerie par résonance magnétique (IRM) permet d’obtenir des images sur corps entier mais ne peut être utilisée pour le suivi peropératoire. Le développement de sondes bimodales, fluorescentes et magnétiques, permet de coupler les avantages des deux techniques.Nous avons choisi de développer des sondes basées sur des nanocristaux fluorescents de CuIn(S,Se)2 car ils présentent une longueur d’onde d’émission modulable sur toute la gamme du proche infrarouge ainsi que des rendements quantiques, sections efficace d’absorption et photostabilités élevés. La croissance d’une coque épaisse de ZnS permet d’augmenter le rendement quantique qui peut atteindre 60 % dans les solvants organiques. L’incorporation d'ions Mn2+ dans la coque de nos objets permet de leur conférer un caractère paramagnétique. Les propriétés optiques et structurales ont été étudiées par spectroscopie (fluorescence et absorbance), RPE, DRX, MET/METHR et analyse élémentaire. Nos sondes sont transférées en milieu aqueux par un échange de ligands qui ne modifie pas leurs propriétés. Des mesures de relaxivités longitudinales ont permis de confirmer leur potentiel comme agent de contraste pour l’IRM pondérée en T1 et nous avons apporté une preuve de principe de l’utilisation de nos sondes in vivo en marquant des ganglions lymphatiques chez la souris.Fluorescence imaging is a promising technique for image-guided surgery. Because of diffusion and absorption of light by tissues, the low penetration depth (less than a millimeter) in the visible spectral range, which can reach a few centimeters in the near infrared (NIR) spectral range (700-1000 nm), limits its use. To overcome this limitation, fluorescence imgaging can be coupled with magnetic resonance imaging (MRI) which provides whole body images but cannot be used for intraoperative monitoring. Thus, the development of bimodal fluorescent and magnetic (for MRI) probes offers the opportunity to combine advantages from both imaging modalities.In this regard, we chose to use CuIn(S,Se)2 fluorescent semiconductor nanocrystals(or quantum dots) as a platform for the development of our probes. They display a size-tunable emission wavelength over the NIR spectral range and high quantum yield, absorption cross section and photostability. The growth of a thick shell of ZnS on these nanoparticles can increase the quantum yield up to 60 % in organic media.The incorporation of Mn2+ ions in the shell gives our probes a paramagnetic behavior. The influence of doping level on structural and optical properties is investigated using fluorescence and absorbance spectroscopy, EPR, XRD, TEM/HRTEM and elemental analysis. Our probes are solubilized in water through a ligand exchange and their properties remain stable in water. Longitudinal relaxivity measurements show that these probes can be used as MRI T1 contrast agents. As a proof-of-principle, we demonstrate that these probes can be used for the detection of lymph nodes in vivo
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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