1,721,009 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
Contribution à la compréhension des réactions ion gaz dans les cellules de collision-réaction des ICP-MS :Application à la résolution d’interférences isobariques et poly-atomiques
No full textInductively Coupled Plasma Mass Spectrometry (ICP-MS) emerged as the most essential technique in inorganic analytical chemistry thanks to its numerous assets, particularly its flexibility, its sensitivity and its reproducibility. As part of the elementary and isotopic analysis of irradiated fuel and transmutation target, the analyst is faced with a complex mass spectrum, due to the presence of many radionuclides. ICP-MS can not differentiate ions with the same mass, which induces isobaric and polyatomic interferences when the ions at the same mass are different chemical species. Last generations of ICP-MS have introduced collision reaction cells. It can in situ reduce these isobaric or polyatomic interferences. The cell is a multipol (quadrupole, hexapole or octopole) device filled with a collision and/or reaction gas. The gas molecules collide or possibly react with the ion beam, which eliminates or reduces interferences. Such resolution of interferences is based on the difference of chemical behaviours between the analyte and the interfering species: the choice of the gas is crucial. A better understanding of the “ion – gaz” reaction should help choosing the reacting gases.Three ICP-MS, with the different cell geometries, were used for this study: Perkin Elmer Elan DRC e (quadrupole), Thermo Fischer X serie II (hexapole) and Agilent Technologies 7700x (octopole). The effects of the cell geometry on different experimental parameters and on the resolution of the 56Fe+/40Ar16O+ polyatomic interferences were examined to measure iron at trace or ultra-trace level. This preliminary study was applied to measure iron as impurities in uranium oxide, the method was then validated with a Certified Reference Material.The reactivities of transition metals (Zr, Ru, Pd, Ag, Cd, Sn), lanthanides (La, Ce, Nd, Sm, Eu, Gd, Dy, Er and Yb) and actinides (U, Np, Pu, Am and Cm), elements of interest in the nuclear field, are studied with numerous gases (O2, CO, CO2, N2O, NO, CH4, C2H4, C3H8, NH3, CH3Cl and COS). Among these gases, ammonia appears to be a selective gas for lanthanides and actinides. DFT (Density Functional Theory) and ab initio calculations (MP2 and CCSD(T)) were able to reproduce the reactivity differences among lanthanide cations (La+, Sm+, Eu+ and Gd+). Reaction paths, potential energy surfaces, molecular orbitals and the influence of the electronic configuration along the reaction path are used to propose an explanation for the observed differences in the chemical behaviours. A few experimental results and quantum calculations indicate how to extend these explanations to actinides.La Spectrométrie de Masse par Plasma à Couplage Inductif (ICP-MS) s’est imposée comme technique d’analyse inorganique, de par sa souplesse d’utilisation, sa sensibilité et sa reproductibilité. L’analyse élémentaire et isotopique des combustibles nucléaires irradiés et de cibles de transmutation, doit faire face à un spectre de masse riche, dû à la présence de nombreux radionucléides. La technique ICP-MS ne peut toutefois pas différencier les ions de même masse ce qui induit des interférences isobariques et poly-atomiques quand les ions de même masse sont des espèces chimiques différentes. La majorité des ICP-MS de nouvelles générations sont équipés d’un dispositif de cellule de collision-réaction permettant la résolution in situ de telles interférences. Ce dispositif est un multipôle (quadripôle, hexapôle ou octopôle) rempli de gaz dont les molécules percutent les ions formés dans le plasma puis éventuellement réagissent. La résolution des interférences est alors basée sur la différence de réactivité chimique qui peut exister entre l’ion d’intérêt et son interférant, vis-à-vis d’un gaz de réaction donné : le choix du gaz est essentiel. Une meilleure compréhension des réactions « ions – gaz » pourrait ainsi aider à choisir le gaz réactif.Trois ICP-MS, avec différentes géométries de cellule de collision-réaction, ont été utilisés pour cette étude : Perkin Elmer Elan DRC e (quadripôle), Thermo Fischer X serie II (hexapôle) et Agilent Technologies 7700x (octopôle). L’influence de la géométrie de la cellule sur différents paramètres expérimentaux et sur la résolution de l’interférence poly-atomique 56Fe+/40Ar16O+ a été déterminée afin de mesurer le fer à l’état de trace ou d’ultra-trace. Cette étude préliminaire a ensuite été appliquée pour mesurer le fer en tant qu’impureté dans l’oxyde d’uranium, puis valider la méthode à l’aide d’un matériau de référence.La réactivité de métaux de transition (Zr, Ru, Pd, Ag, Cd, Sn), de lanthanides (La, Ce, Nd, Sm, Eu, Gd, Dy, Er et Yb) et d’actinides (U, Np, Pu, Am et Cm), éléments d’intérêts dans le domaine du nucléaire, a été testée vis-à-vis de nombreux gaz (O2, CO, CO2, N2O, NO, CH4, C2H4, C3H8, NH3, CH3Cl et COS). Parmi ces gaz, l’ammoniac est un gaz sélectif de lanthanides entre eux et aussi d'actinides. L’étude théorique, menée par des calculs DFT (Théorie de la Fonctionnelle de la Densité) et ab initio (MP2 et CCSD(T)) a permis de reproduire la différence de réactivité de quatre cations lanthanide (La+, Sm+, Eu+ et Gd+). Les chemins de réactions, les profils d’énergie potentielle, les orbitales moléculaires et l’influence de la configuration électronique le long du chemin de réaction ont permis de proposer une explication de la différence de réactivité observée. Quelques résultats expérimentaux et calculs de chimie quantique indiquent comment étendre ces explications aux actinides
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
Contribution to the understanding of ion-gas reaction in the reaction collision cell of the inductively coupled plasma mass spectrometry ICP-MS : application to the resolution of isobaric and polyatomic interferences
No full textLa Spectrométrie de Masse par Plasma à Couplage Inductif (ICP-MS) s’est imposée comme technique d’analyse inorganique, de par sa souplesse d’utilisation, sa sensibilité et sa reproductibilité. L’analyse élémentaire et isotopique des combustibles nucléaires irradiés et de cibles de transmutation, doit faire face à un spectre de masse riche, dû à la présence de nombreux radionucléides. La technique ICP-MS ne peut toutefois pas différencier les ions de même masse ce qui induit des interférences isobariques et poly-atomiques quand les ions de même masse sont des espèces chimiques différentes. La majorité des ICP-MS de nouvelles générations sont équipés d’un dispositif de cellule de collision-réaction permettant la résolution in situ de telles interférences. Ce dispositif est un multipôle (quadripôle, hexapôle ou octopôle) rempli de gaz dont les molécules percutent les ions formés dans le plasma puis éventuellement réagissent. La résolution des interférences est alors basée sur la différence de réactivité chimique qui peut exister entre l’ion d’intérêt et son interférant, vis-à-vis d’un gaz de réaction donné : le choix du gaz est essentiel. Une meilleure compréhension des réactions « ions – gaz » pourrait ainsi aider à choisir le gaz réactif. Trois ICP-MS, avec différentes géométries de cellule de collision-réaction, ont été utilisés pour cette étude : Perkin Elmer Elan DRC e (quadripôle), Thermo Fischer X serie II (hexapôle) et Agilent Technologies 7700x (octopôle). L’influence de la géométrie de la cellule sur différents paramètres expérimentaux et sur la résolution de l’interférence poly-atomique 56Fe+/40Ar16O+ a été déterminée afin de mesurer le fer à l’état de trace ou d’ultra-trace. Cette étude préliminaire a ensuite été appliquée pour mesurer le fer en tant qu’impureté dans l’oxyde d’uranium, puis valider la méthode à l’aide d’un matériau de référence. La réactivité de métaux de transition (Zr, Ru, Pd, Ag, Cd, Sn), de lanthanides (La, Ce, Nd, Sm, Eu, Gd, Dy, Er et Yb) et d’actinides (U, Np, Pu, Am et Cm), éléments d’intérêts dans le domaine du nucléaire, a été testée vis-à-vis de nombreux gaz (O2, CO, CO2, N2O, NO, CH4, C2H4, C3H8, NH3, CH3Cl et COS). Parmi ces gaz, l’ammoniac est un gaz sélectif de lanthanides entre eux et aussi d'actinides. L’étude théorique, menée par des calculs DFT (Théorie de la Fonctionnelle de la Densité) et ab initio (MP2 et CCSD(T)) a permis de reproduire la différence de réactivité de quatre cations lanthanide (La+, Sm+, Eu+ et Gd+). Les chemins de réactions, les profils d’énergie potentielle, les orbitales moléculaires et l’influence de la configuration électronique le long du chemin de réaction ont permis de proposer une explication de la différence de réactivité observée. Quelques résultats expérimentaux et calculs de chimie quantique indiquent comment étendre ces explications aux actinides.Inductively Coupled Plasma Mass Spectrometry (ICP-MS) emerged as the most essential technique in inorganic analytical chemistry thanks to its numerous assets, particularly its flexibility, its sensitivity and its reproducibility. As part of the elementary and isotopic analysis of irradiated fuel and transmutation target, the analyst is faced with a complex mass spectrum, due to the presence of many radionuclides. ICP-MS can not differentiate ions with the same mass, which induces isobaric and polyatomic interferences when the ions at the same mass are different chemical species. Last generations of ICP-MS have introduced collision reaction cells. It can in situ reduce these isobaric or polyatomic interferences. The cell is a multipol (quadrupole, hexapole or octopole) device filled with a collision and/or reaction gas. The gas molecules collide or possibly react with the ion beam, which eliminates or reduces interferences. Such resolution of interferences is based on the difference of chemical behaviours between the analyte and the interfering species: the choice of the gas is crucial. A better understanding of the “ion – gaz” reaction should help choosing the reacting gases. Three ICP-MS, with the different cell geometries, were used for this study: Perkin Elmer Elan DRC e (quadrupole), Thermo Fischer X serie II (hexapole) and Agilent Technologies 7700x (octopole). The effects of the cell geometry on different experimental parameters and on the resolution of the 56Fe+/40Ar16O+ polyatomic interferences were examined to measure iron at trace or ultra-trace level. This preliminary study was applied to measure iron as impurities in uranium oxide, the method was then validated with a Certified Reference Material. The reactivities of transition metals (Zr, Ru, Pd, Ag, Cd, Sn), lanthanides (La, Ce, Nd, Sm, Eu, Gd, Dy, Er and Yb) and actinides (U, Np, Pu, Am and Cm), elements of interest in the nuclear field, are studied with numerous gases (O2, CO, CO2, N2O, NO, CH4, C2H4, C3H8, NH3, CH3Cl and COS). Among these gases, ammonia appears to be a selective gas for lanthanides and actinides. DFT (Density Functional Theory) and ab initio calculations (MP2 and CCSD(T)) were able to reproduce the reactivity differences among lanthanide cations (La+, Sm+, Eu+ and Gd+). Reaction paths, potential energy surfaces, molecular orbitals and the influence of the electronic configuration along the reaction path are used to propose an explanation for the observed differences in the chemical behaviours. A few experimental results and quantum calculations indicate how to extend these explanations to actinides
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
Uranium and plutonium isotopic analysis in Atalante facility for the 2022-NMRoRo
No full textInternational audienc
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