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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
Exploration du diagramme de phase de l'hématite Fe2O3 par compression dynamique laser
No full textThe study of Fe2O3 under extreme conditions is important to better understand the interiors of planets, such as the Earth or super-Earths, and meteorite impacts which are fundamental processes of planetary accretion. In order to study these phenomena, we have used the technique of dynamic compression by laser shock, coupled with time-resolved diagnostics: VISAR (interferometer allowing measurements of surface and interface velocities), and X-ray diffraction and absorption during the shocks and releases. We have accurately measured, for the first time, the equation of state of Fe2O3 at very high pressure, up to 700 GPa, and determined that Fe2O3 melting occurs under shock at 135 GPa and 3000 K. This measurement led us to question the calculated temperature of the currently available SESAME equation of state table for Fe2O3. The measurements also showed that the high pressure phases observed in static compression are not identical to those revealed by dynamic compression. Thus the spin transition (high spin to low spin) of Fe3+ in Fe2O3 is, under dynamic compression, isostructural with volume reduction, while it is probably accompanied by a structural change in static compression. Such differences indicate a kinetic limitation of the use of laser shocks for the study of planetary interiors and conversely of static techniques for that of fast phenomena (ns). Finally, we have highlighted the reduction of iron from Fe3+ to a medium redox state Fe2.2+ in Fe2O3 upon release after a shock at 120 GPa, over a characteristic time of the order of nanoseconds. This observation highlights the rapidity of the redox mechanism, suggesting a probable reduction of Fe3+ during meteorite impacts, which explains some observations made in tektites.L'étude de Fe2O3 en conditions extrêmes est importante pour mieux comprendre les intérieurs de planètes, telles que la Terre ou les super-Terres, et les impacts de météorites, processus fondamentaux de l'accrétion planétaire. Afin d'étudier ces phénomènes, nous avons utilisé la technique de compression dynamique par choc laser, couplée à des diagnostics résolus en temps : le VISAR (interféromètre permettant des mesures de vitesses de surfaces et interfaces), et la diffraction et l'absorption X pendant les chocs et détentes. Nous avons mesuré avec précision, pour la première fois, l'équation d'état de Fe2O3 à très haute pression, jusqu'à 700 GPa et avons déterminé que la fusion de Fe2O3 se produisait sous choc à 135 GPa et 3000 K. Cette mesure nous a conduits à remettre en question la température calculée de la table d'équation d'état SESAME actuellement disponible pour Fe2O3. Les mesures ont en outre montrées que les phases haute pression observées en compression statique ne sont pas identiques à celles mises en évidence par compression dynamique. Ainsi la transition de spin (haut spin vers bas spin) du Fe3+ dans Fe2O3 est, en compression dynamique, isostructurale avec réduction de volume, alors qu'elle s'accompagne probablement d'un changement structural en statique. De telles différences indiquent une limitation cinétique de l'utilisation des chocs laser pour l'étude des intérieurs planétaires et inversement des techniques statiques pour celle des phénomènes rapides (ns). Enfin, nous avons mis en évidence la réduction du fer, de Fe3+ à un état redox moyen Fe2.2+, dans Fe2O3 en détente après un choc à 120 GPa, sur un temps caractéristique de l'ordre de la nanoseconde. Cette observation met en lumière la rapidité du mécanisme redox, suggérant une réduction probable du Fe3+ lors d'un impact de météorite permettant d'expliquer certaines observations faite dans les tectites
Exploration of Fe2O3 phase diagram with laser shock compression
No full textL'étude de Fe2O3 en conditions extrêmes est importante pour mieux comprendre les intérieurs de planètes, telles que la Terre ou les super-Terres, et les impacts de météorites, processus fondamentaux de l'accrétion planétaire. Afin d'étudier ces phénomènes, nous avons utilisé la technique de compression dynamique par choc laser, couplée à des diagnostics résolus en temps : le VISAR (interféromètre permettant des mesures de vitesses de surfaces et interfaces), et la diffraction et l'absorption X pendant les chocs et détentes. Nous avons mesuré avec précision, pour la première fois, l'équation d'état de Fe2O3 à très haute pression, jusqu'à 700 GPa et avons déterminé que la fusion de Fe2O3 se produisait sous choc à 135 GPa et 3000 K. Cette mesure nous a conduits à remettre en question la température calculée de la table d'équation d'état SESAME actuellement disponible pour Fe2O3. Les mesures ont en outre montrées que les phases haute pression observées en compression statique ne sont pas identiques à celles mises en évidence par compression dynamique. Ainsi la transition de spin (haut spin vers bas spin) du Fe3+ dans Fe2O3 est, en compression dynamique, isostructurale avec réduction de volume, alors qu'elle s'accompagne probablement d'un changement structural en statique. De telles différences indiquent une limitation cinétique de l'utilisation des chocs laser pour l'étude des intérieurs planétaires et inversement des techniques statiques pour celle des phénomènes rapides (ns). Enfin, nous avons mis en évidence la réduction du fer, de Fe3+ à un état redox moyen Fe2.2+, dans Fe2O3 en détente après un choc à 120 GPa, sur un temps caractéristique de l'ordre de la nanoseconde. Cette observation met en lumière la rapidité du mécanisme redox, suggérant une réduction probable du Fe3+ lors d'un impact de météorite permettant d'expliquer certaines observations faite dans les tectites.The study of Fe2O3 under extreme conditions is important to better understand the interiors of planets, such as the Earth or super-Earths, and meteorite impacts which are fundamental processes of planetary accretion. In order to study these phenomena, we have used the technique of dynamic compression by laser shock, coupled with time-resolved diagnostics: VISAR (interferometer allowing measurements of surface and interface velocities), and X-ray diffraction and absorption during the shocks and releases. We have accurately measured, for the first time, the equation of state of Fe2O3 at very high pressure, up to 700 GPa, and determined that Fe2O3 melting occurs under shock at 135 GPa and 3000 K. This measurement led us to question the calculated temperature of the currently available SESAME equation of state table for Fe2O3. The measurements also showed that the high pressure phases observed in static compression are not identical to those revealed by dynamic compression. Thus the spin transition (high spin to low spin) of Fe3+ in Fe2O3 is, under dynamic compression, isostructural with volume reduction, while it is probably accompanied by a structural change in static compression. Such differences indicate a kinetic limitation of the use of laser shocks for the study of planetary interiors and conversely of static techniques for that of fast phenomena (ns). Finally, we have highlighted the reduction of iron from Fe3+ to a medium redox state Fe2.2+ in Fe2O3 upon release after a shock at 120 GPa, over a characteristic time of the order of nanoseconds. This observation highlights the rapidity of the redox mechanism, suggesting a probable reduction of Fe3+ during meteorite impacts, which explains some observations made in tektites
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
Exploration du diagramme de phase de l'hématite Fe2O3 par compression dynamique laser
No full textThe study of Fe2O3 under extreme conditions is important to better understand the interiors of planets, such as the Earth or super-Earths, and meteorite impacts which are fundamental processes of planetary accretion. In order to study these phenomena, we have used the technique of dynamic compression by laser shock, coupled with time-resolved diagnostics: VISAR (interferometer allowing measurements of surface and interface velocities), and X-ray diffraction and absorption during the shocks and releases. We have accurately measured, for the first time, the equation of state of Fe2O3 at very high pressure, up to 700 GPa, and determined that Fe2O3 melting occurs under shock at 135 GPa and 3000 K. This measurement led us to question the calculated temperature of the currently available SESAME equation of state table for Fe2O3. The measurements also showed that the high pressure phases observed in static compression are not identical to those revealed by dynamic compression. Thus the spin transition (high spin to low spin) of Fe3+ in Fe2O3 is, under dynamic compression, isostructural with volume reduction, while it is probably accompanied by a structural change in static compression. Such differences indicate a kinetic limitation of the use of laser shocks for the study of planetary interiors and conversely of static techniques for that of fast phenomena (ns). Finally, we have highlighted the reduction of iron from Fe3+ to a medium redox state Fe2.2+ in Fe2O3 upon release after a shock at 120 GPa, over a characteristic time of the order of nanoseconds. This observation highlights the rapidity of the redox mechanism, suggesting a probable reduction of Fe3+ during meteorite impacts, which explains some observations made in tektites.L'étude de Fe2O3 en conditions extrêmes est importante pour mieux comprendre les intérieurs de planètes, telles que la Terre ou les super-Terres, et les impacts de météorites, processus fondamentaux de l'accrétion planétaire. Afin d'étudier ces phénomènes, nous avons utilisé la technique de compression dynamique par choc laser, couplée à des diagnostics résolus en temps : le VISAR (interféromètre permettant des mesures de vitesses de surfaces et interfaces), et la diffraction et l'absorption X pendant les chocs et détentes. Nous avons mesuré avec précision, pour la première fois, l'équation d'état de Fe2O3 à très haute pression, jusqu'à 700 GPa et avons déterminé que la fusion de Fe2O3 se produisait sous choc à 135 GPa et 3000 K. Cette mesure nous a conduits à remettre en question la température calculée de la table d'équation d'état SESAME actuellement disponible pour Fe2O3. Les mesures ont en outre montrées que les phases haute pression observées en compression statique ne sont pas identiques à celles mises en évidence par compression dynamique. Ainsi la transition de spin (haut spin vers bas spin) du Fe3+ dans Fe2O3 est, en compression dynamique, isostructurale avec réduction de volume, alors qu'elle s'accompagne probablement d'un changement structural en statique. De telles différences indiquent une limitation cinétique de l'utilisation des chocs laser pour l'étude des intérieurs planétaires et inversement des techniques statiques pour celle des phénomènes rapides (ns). Enfin, nous avons mis en évidence la réduction du fer, de Fe3+ à un état redox moyen Fe2.2+, dans Fe2O3 en détente après un choc à 120 GPa, sur un temps caractéristique de l'ordre de la nanoseconde. Cette observation met en lumière la rapidité du mécanisme redox, suggérant une réduction probable du Fe3+ lors d'un impact de météorite permettant d'expliquer certaines observations faite dans les tectites
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
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
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