1,721,013 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
Design, synthesis and characterisation of porphyrin-based Metal Organic Frameworks
No full textLes porphyrines sont des composés macrocycliques naturels étudiés de manière approfondie en tant que mimétiques enzymatiques ou catalyseurs d'oxydation en milieu homogène. L'incorporation de porphyrines dans des réseaux de polymères de coordination métal-organique (MOFs), qui constituent une famille de composés cristallins poreux connus pour leur diversité structurelle, pourrait conduire à des matériaux constitués de réseaux étendus présentant les mêmes propriétés que les systèmes homogènes. Toutefois de nombreux travaux ont montré que la limitation majeure pour des applications à grande échelle des MOFs est leur stabilité.La stabilité de ces matériaux peut être accrue en employant des cations métalliques de valence élevée dans l'unité de construction inorganique (tels que Fe3+, Al3+, Zr4+) et / ou en modifiant la fonction coordinante du ligand organique.Ce travail est relatif à l'étude de la réactivité de ligands porphyriniques portant diverses fonctions coordinantes, avec des ions métalliques de valence élevée. L'influence des paramètres de synthèse et la caractérisation approfondie de ces MOFs ont été réalisées par une combinaison de techniques expérimentales (diffraction des rayons X, analyse thermogravimétrique, spectroscopie UV-vis, spectroscopie infrarouge, études de sorption, etc.). Dans un premier temps, l'étude s'est focalisée sur des MOFs porphyriniques à base de groupements carboxylates stables connus, ce qui a conduit à de nouvelles variantes de ces matériaux. Dans un second temps il est démontré que les topologies des réseaux observées sur un ligand porphyrinique à base carboxylate peuvent être étendues à d'autres fonctionnalités avec la synthèse d'un nouveau MOF à base de tétrazolate. L'amélioration de la stabilité a également été explorée avec des ligands portant des fonctions phénol qui ont abouti à l'élaboration de nouveaux réseaux de coordination. La synthèse et l'étude de stabilité d'un MOF porphyrinique à base de gallate est rapportée. L'évaluation préliminaire de l'activité catalytique de certains des MOFs élaborés est également décritePorphyrins are important macrocyclic compounds which are prevalent in nature and have been extensively studied by chemists in homogeneous catalysis as enzyme mimics. Incorporating porphyrins in metal-organic frameworks (MOFs) offer an ideal opportunity to obtain material with extended frameworks possessing the same properties as the homogenous systems. Much work has been done on porphyrinic MOFs but their stability remains a problem and a major limitation for possible wide scale applications. In literature, more stable MOFs have been realised using high valent metal ions in the inorganic building unit (such as Fe3+, Al3+, Zr4+) and/or by using more basic functionalities in the organic linker. However, regarding porphyrinic MOFs, little work is reported with ligands based on functionalities other than carboxylic acid groups. Therefore, our work focused on investigating the reactivity of porphyrinic ligands carrying various functionalities with high valent metal ions. More precisely, we focused on the design, synthesis optimisation and characterisation of such materials. This included studying existing stable carboxylate porphyrinic frameworks with a goal of incorporating new functionalities, which led to new variations of these materials. Our work also demonstrated that the framework topologies observed with carboxylate based porphyrinic ligand can be expanded to other functionalities with the synthesis of a new tetrazolate based porphyrinic MOF. MOF synthesis was also investigated with phenolate functionalised ligands and resulted in the first gallate based porphyrinic MOF reported. The stability of this new material was assessed. This manuscript discusses the synthesis and the characterisation of these MOFs via a combination of experimental techniques (X-ray diffraction, TGA analysis, UV-vis spectroscopy, IR-spectroscopy, sorption studies etc.). The preliminary evaluation of the catalytic activity of some of the MOFs is also describe
Development of 4f ion complexes from ß-diketone ligands : study of single molecule magnet and luminescence properties
No full textAu cours de ces dernières décennies, les cations lanthanides trivalents ont été à l'honneur en matière de haute technologie. Ces éléments sont utilisés dans des applications stratégiques telles que les lunettes optiques et les lasers, les télécommunications, l'éclairage et les écrans, les matériaux magnétiques, les disques durs, les encres de sécurité et les labels de contrefaçon, la catalyse, les biosciences et la médecine, pour n'en citer que quelques exemples. Cet intérêt croissant pour ces métaux fait de la chimie de coordination des éléments 4f un champ de recherche attrayant avec des perspectives presque illimitées. Ainsi la quête de nouveaux matériaux afin d'améliorer le caractère apporté par les éléments 4f au sein de complexes moléculaires n'a cessé de s'intensifier au cours des dernières décennies. Dans ce cadre, la compréhension précise de la relation structure cristalline-propriétés physiques (magnétisme, luminescence) devient primordiale puisqu'elle permet d'améliorer les objets synthétisés. Par conséquent, la conception de nouvelles architectures moléculaires à base d'ions lanthanide se révèle être nécessaire pour élargir la base de données disponibles et ainsi améliorer les connaissances pour ensuite optimiser les applications. Le présent travail de recherche s'insère parfaitement dans cette thématique, à savoir améliorer les connaissances sur les corrélations possibles entre la structure cristalline d'un complexe d'ions lanthanide et ses propriétés. Au cours de cette thèse, différents systèmes moléculaires originaux ont été élaborés et nous nous sommes particulièrement intéressés à la description et la compréhension des propriétés magnétiques et de luminescence. Les complexes ont été construits avec des ligands de type β-dicétone. Ces dernières offrent différents modes de coordinations qui ont permis de mettre en œuvre de nouvelles familles de complexes de lanthanides. Selon les conditions de synthèse, la nuclearité des complexes est contrôlée de [Ln1] à [Ln9]. De même, il a été possible en ajustant les conditions de synthèse de contrôler finement l'environnement des ions lanthanide au sein de ces complexes. Par dopages des clusters à forte nuclearités, nous avons pu exacerber les propriétés de luminescence des composés étudiées. Les édifices dinucléaires, trinucléaires et tétranucléaires présentent quant à eux un comportement de molécule-aimant et certains d'entre eux sont des molécules-aimants avec un moment toroïdal. Enfin, certains de ces complexes peuvent également se comporter comme des matériaux bi-fonctionnels combinant propriété de molécule-aimant et de luminescente. Ainsi l'étude du caractère spectroscopique et magnétique de ces entités nous a permis de rationaliser les propriétés physiques par rapport à la structureOver the last few decades, lanthanides have been highlighted in high technology. These elements are used in strategic applications such as optical glasses and lasers, telecommunications, lighting and screens, magnetic materials, hard drive, security inks and counterfeit labels, catalysis, biosciences and medicine…This progress makes the coordination chemistry of 4f elements a mature and attractive field of research with almost unlimited perspectives which brings a new perception, a new area to coordination chemistry. The quest for new materials to improve the character provided by the 4f elements is steadily intensifying. In this context, the precise understanding of the structure-property relationship takes an important place, since this latter derives the properties. Consequently, it is still necessary to design new structures to expand the available database and thus improve knowledge and then promote applications. The present work is part of this idea to provide more information on the structure-properties relationship of lanthanide complexes. Indeed, during this thesis different original nuclear systems were developed and we were particularly interested in the description and understanding of the magnetic and luminescence properties. Molecular entities were constructed with β-diketone ligands. The latter offer different modes of coordination that have allowed the design of new families of lanthanide complexes. According to synthesis conditions, the nuclearity of the complexes is controlled from [Ln1] to [Ln9]. By doping the complexes with high nuclearity we were able to exacerbate the luminescence properties of the compounds studied. In regards to magnetism, the dinuclear, trinuclear and tetranuclear structures exhibit a single molecule magnet (SMM) behavior and some are magnet molecules with a toroidal moment. Other such complexes can also behave as bi-functional materials, combining SMM and luminescent property. Thus the study of the spectroscopic and magnetic character of these entities enabled us to rationalize the physical properties with respect to the structure, which is a great advantage in the field of coordination of the lanthanide
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
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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