1,721,036 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
Bidimensionnal nanostructuration of sapphire vicinal surfaces : X-ray scattering quantitative analysi
No full textLes systèmes nanostructurés composés de nanoparticules déposées à la surface d’oxyde présentent à la fois un intérêt fondamental et technologique. Les propriétés finales de tels systèmes dépendent principalement de la forme et de la taille des nanoparticules déposées ainsi que de leur organisation sur la surface. Dans ce contexte général, l’utilisation de surfaces vicinales apparaît comme un moyen intéressant pour réaliser des substrats gabarits sur lesquels des particules pourront être déposées. Ce travail est consacré à l’étude de la nanostructuration bidimensionnelle (2D) de surfaces vicinales de saphir obtenue dans certaines conditions expérimentales (orientation de la surface vicinale et paramètres du traitement thermique). Les principaux objectifs de cette étude sont de décrire la morphologie de surface de ces échantillons présentant une mise en ordre 2D mais aussi de proposer un mécanisme concernant le passage de l’organisation monodimensionnelle (1D) à l’organisation 2D. La morphologie des surfaces vicinales d’alumine α, traitées à 1250 °C sous atmosphère d’oxygène pur pendant des durées allant jusqu’à 380 h, a été étudiée par des techniques expérimentales complémentaires : la microscopie à force atomique (AFM), la diffusion centrale des rayons X sous incidence rasante (GISAXS) et la diffraction de surface (GIXD). Les différents résultats ainsi obtenus nous ont permis de montrer que la surface présentant une organisation 2D pouvait être décrite par une assemblée de pyramides, dont la base est un triangle isocèle, décorant un réseau rectangulaire centré. Nous avons déterminé de façon très précise la forme de ce tétraèdre irrégulier qui a été décrit selon les caractéristiques cristallographiques du saphir. Il a de plus été montré qu’un phénomène de méandrage des bords de marches est probablement à l’origine de la transition entre les réseaux 1D et 2D qui n’est observée que lorsque les bords de marches initiaux sont rectilignes.Nanostructured systems based on nanoparticles deposited onto oxide surfaces have both a fundamental and technological interests. Final properties of such systems depend mostly on the shape and size of the nanoparticles and also on their spatial organization on the surface. In this general context, the use of vicinal surfaces appears to be an interesting way of producing templates for ordering nanoparticles. This work is devoted to the study of two-dimension (2D) nanostructuration of sapphire vicinal surfaces obtained under specific experimental conditions (vicinal surface orientation and thermal treatment parameters). The main objectives of this study were to describe the surface morphology of the samples having the 2D ordering and also to propose a mechanism regarding the transition from the 1D to the 2D ordering.Morphology of sapphire vicinal surfaces, annealed at 1250 °C under pure oxygen atmosphere during various durations up to 380 h, was studied by complementary technics: atomic force microscopy (AFM), grazing-incidence small-angle X-rays scattering (GISAXS), and grazing-incidence X-rays diffraction (GIXD). Results allowed us to describe the 2D ordered surface by being an assembly of pyramids with an isosceles triangle base decorating a rectangular centered lattice. The shape of those irregular tetrahedrons has been precisely determined with the crystallographic characteristics of sapphire. It has also been shown that a meandering step-edge phenomenon is probably the starting point of the transition between 1D and 2D lattices obtained when initial step-edges are straight
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
Nanostructuration by phase separation and crystallization at low temperature in amorphous oxides produced by the sol-gel process
No full textCe travail porte sur l’élaboration de matériaux nanostructurés et le contrôle de la formation de nanocristaux d’oxyde d’étain dans une matrice de silice amorphe obtenue par voie sol-gel. Préalablement à l’étude structurale et microstructurale des xérogels, une première partie de ces travaux de thèse concerne le procédé sol-gel. Le lavage des gels par des solutions hydro-alcooliques permet d’extraire une quantité importante d’acide chlorhydrique après gélification. Ainsi si les solutions de lavage sont renouvelées, 50 % de l’acide introduit peut être retiré. Ce lavage, associé avec un séchage contrôlé, a également permis de réduire significativement la durée du séchage et d’obtenir des xérogels centimétriques non fissurés.La seconde partie de ce travail a porté sur l’étude structurale et microstructurale des xérogels réalisée au travers de mesures de diffraction des rayons X ex situ ou de diffusion centrale et diffraction des rayons X couplée in situ en fonction de la température sur des lignes de lumière situées autour de sources synchrotrons. Nous avons montré que dans des xérogels contenant 10 % d’étain, la quantité de cristaux nanométriques d'oxyde d'étain peut augmenter continuellement sans que leur taille moyenne ne s’accroisse. La taille moyenne la plus faible est obtenue après un prétraitement thermique de séparation de phases préalable à celui de cristallisation et plus ce traitement est long plus la taille des cristaux est faible. Cette étude a été complétée par des traitements thermiques effectués in situ afin de suivre simultanément la séparation de phases et la cristallisation. Ces mesures ont permis d’observer le phénomène de séparation de phases dans les xérogels contenant 10 % d’étain et dont la quantité cristallisée obtenue lors d’un traitement thermique à 350 °C est la plus importante au regard des autres températures de traitement thermique et des concentrations en étain.This PhD work deals with the development of nanostructured oxide materials and the control of the formation of tin oxide nanocrystals in an amorphous silica matrix obtained by sol-gel process. Prior to the structural and microstructural study of xerogels, a first part of this work concerns the sol-gel process. Washing the gels with hydroalcoholic solutions allows to extract a significant quantity of hydrochloric acid after gelation. Thus, if the washing solutions are renewed, 50% of the acid introduced can be removed. This washing, combined with improvement of the drying process, allowed to reduce the drying duration and finally to obtain bulk xerogels exhibiting a centimetric size.The second part of this work focuses on the structural and microstructural evolution of xerogels through thermal treatments. The results of this second part are obtained through ex situ measurements of X-ray diffraction or coupled small angle X-ray scattering and X-ray diffraction experiments realized in situ as a function of temperature. In both cases the measurements have been performed on synchrotron beamlines. We show that in xerogels containing 10% tin, the amount of nanosized tin oxide crystals can continuously increases without increasing the average size of these crystals. The lowest average size is obtained after a phase separation thermal pretreatment before crystallization and the longer this treatment is, the smaller the size of the crystals. This study is completed by heat treatments carried out in situ in order to simultaneously evidence phase separation and crystallization. These measurements allow to observe the phenomenon of phase separation by small angle X-ray scattering in xerogels containing 10% tin and whose crystallized quantity obtained during a thermal treatment at 350 °C is the highest compared to other heat treatment temperatures and tin concentrations
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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