1,721,068 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
Dosimétrie personnalisée par simulation Monte Carlo GATE sur grille de calcul. Application à la curiethérapie oculaire.
No full textN° d'ordre : DU 1607, EDSF 463Although often quite time consuming, Monte Carlo method is the calculation algorithm that most closely models the actual physics of the energy deposition process. The idea is to use Monte Carlo calculations in daily cancer treatment using radiation to compete with treatment planning systems (TPS) in the delivering of absorbed dose to tumour for specific treatments. To achieve this goal, two points have been particularly studied in this thesis: the validation of the GATE platform for dosimetry applications using electrons, with a specific study concerning ocular brachytherapy treatments using 106Ru/106Rh ophthalmic applicators and the deployment of GATE simulations in a grid environment to reduce the very high computation time of those simulations.Monoenergetic and polyenergetic electron dose point kernels have been simulated using the GATE platform and compared with other Monte Carlo codes. Three versions of the GEANT4 physics package have been used for the comparisons (5.2, 6.2 and 7.0). Results show that the Multiple Scattering implementation is responsible for the discrepancies observed between the codes. Simulations of ocular brachytherapy treatments compared with Monte Carlo and measurements show a good agreement. The transcription of Hounsfield units from CT images of patient's anatomy to tissue parameters is the other work presented for a next usage of GATE on voxelized images for personnalized dosimetry. The DataGrid and then the EGEE infrastructures were used to deploy GATE simulations to reduce their computation time in order to use them in clinical practice.The method used to parallelize the GATE simulations is the splitting of the random number generator (RNG) into independent sequences. Computing time tests performed on the grid testbeds show that a significant speed-up is obtained. Functionalities to split, launch and monitor GATE simulations on a grid infrastructure have been implemented on the GENIUS web portal. A first prototype of this portal is accessible from hospital to use the accurate Monte Carlo algorithms in a transparent and secure way for ocular cancer treatments.Bien que souvent assez consommatrice en temps de calcul, la méthode Monte Carlo est l'algorithme de calcul qui modélise au plus près la physique liée aux processus de dépôts d'énergie. L'idée est d'utiliser les calculs Monte Carlo dans le traitement quotidien du cancer par rayonnement pour rivaliser avec les systèmes de planification de traitement (TPS) existants dans le but de délivrer une dose absorbée à la tumeur pour des traitements spécifiques. Pour atteindre cet objectif, deux points ont été particulièrement étudiés au cours de cette thèse : la validation de la plate-forme de simulation GATE pour des applications en dosimétrie utilisant des électrons, une étude particulière est faite concernant les traitements de curiethérapie oculaire utilisant des applicateurs ophtalmiques de 106Ru/106Rh, et le déploiement des simulations GATE dans un environnement de grille pour réduire les temps de calcul très élevés de ces simulations.Des points kernels de dose d'électrons mono-énergétiques et poly-énergétiques ont été simulés en utilisant la plate-forme GATE et comparés à d'autres codes Monte Carlo. Trois versions des packages de librairies ont été utilisées pour les comparaisons (5.2, 6.2 et 7.0). Les résultats montrent que l'implémentation de la diffusion multiple est responsable des différences observées entre les codes. Les simulations de traitements de curiethérapie oculaire comparées avec d'autres Monte Carlo et des mesures montrent un bon accord. La transcription des unités Hounsfield, à partir des données scanner sur l'anatomie du patient, en paramètres tissulaires est l'autre étude présentée pour une utilisation prochaine de GATE sur des images voxélisées pour la dosimétrie personnalisée. Les infrastructures des projets DataGrid puis d'EGEE ont été utilisées pour déployer les simulations GATE afin de réduire leur temps de calcul dans le but de les utiliser en routine clinique.La méthode utilisée pour paralléliser les simulations GATE est la division du générateur de nombres aléatoires (RNG) en séquences indépendantes. Des tests de temps de calcul réalisés sur des bancs tests de grille montrent qu'un gain significatif est obtenu. Les fonctionnalités pour diviser, lancer et contrôler les simulations GATE sur une infrastructure de grille ont été implémentées sur le portail web GENIUS. Un premier prototype de ce portail est accessible à partir d'un centre hospitalier pour l'utilisation de la précision des algorithmes Monte Carlo de manière transparente et sécurisée pour des traitements de cancer de l'œil
La plateforme de simulation Monte Carlo GATe pour l’hadronthérapie
No full textNational audienceOn the behalf of the OpenGATE collaboratio
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
Modélisation de l'exposition aux rayonnements ionisants des microorganismes vivant dans des sources minérales naturellement radioactives
No full textLa radioactivité est présente sur terre depuis son origine. Le rôle qu'elle a pu jouer dans l'émergence et l'évolution de la vie est encore inconnu. Les premières traces de vie terrestre se trouvent dans les dépôts de sources hydrothermales datées d'il y a 3.7 milliards d'années. Les sources minérales sont des écosystèmes insulaires dont les conditions ont très peu évolué au cours des siècles passés, offrant ainsi une fenêtre exceptionnelle sur l'histoire de la vie sur terre. Dans les sources les plus radioactives, les rayonnements ionisants peuvent être un « moteur abiotique » impactant la diversité et la structure des communautés microbiennes. Cependant, une question scientifique majeure est de connaître la dose reçue par les organismes vivant dans les sources. Sur la base de la caractérisation analytique de sources minérales radioactives sélectionnées dans la région Auvergne en France, une simulation Monte-Carlo utilisant GATE a été réalisée pour évaluer la dose reçue de l'exposition interne et externe aux radioéléments présents dans l'environnement. Les analyses radiologiques de multiples échantillons de sédiments et d'eau provenant de plus de 20 sources ont montré que le Ra-226 dans les sédiments et le Rn-222 dans l'eau étaient la principale source de radiotoxicité dans ces écosystèmes de par leur désintégration αlpha. L'analyse des dommages causés à l'ADN de microalgues (diatomées) a été évaluée à l'aide de la boîte à outils Monte-Carlo Geant4-DNA. Elle montre que dans les sources les plus radioactives, la radiotoxicité est un facteur abiotique potentiellement important car le taux de cassures double brin est comparable au taux de mutation spontanée. Ces résultats devront être affinés lorsque des connaissances supplémentaires seront acquises sur la bioaccumulation des radioéléments dans les diatomées vivant dans les sources. Des connaissances supplémentaires sont également nécessaires sur le génome et la physiologie des diatomées. Enfin, la comparaison avec ERICA, l'outil de référence pour la radioprotection de l'environnement, a montré qu'il doit être utilisé avec une grande prudence lors de l'évaluation de l'exposition des micro-organismes dans les sources minérales. GATE doit être vu comme l'outil complémentaire à ERICA pour caractériser à l'échelle micrométrique le débit de dose aux micro-organismes dans les écosystèmes naturels.Radiation has been present on Earth since its origin. The role it may have played in the emergence and evolution of life is still unknown. The earliest traces of terrestrial life are found in the deposits of hydrothermal springs dated 3.7 billion years ago.Mineral springs are isolated ecosystems whose conditions have changed very little over the past centuries, thus offering an exceptional window on the history of life on Earth.In the most radioactive springs, ionizing radiation can be an “abiotic driver” impacting the diversity and structure of microbial communities. However, a major scientific question is to know the dose received by the microorganisms living in the mineral springs. Based on the analytical characterization of selected radioactive mineral springs in the Auvergne region of France, Monte Carlo simulations using GATE were conducted to evaluate the dose rates received by microorganisms from internal and external exposure due to the radioelements present in the mineral springs environment. Radiological analyses of multiple sediment and water samples coming from more than 20 mineral springs have shown that Ra-226 in the sediments and Rn-222 in the water were the dominant source of radiotoxicity in these ecosystems through their α-decay.DNA damages of microalgae (diatoms) were evaluated using the Geant4-DNA Monte Carlo toolkit. It is shown that in the most radioactive springs radiotoxicity could be an abiotic driver, as the rate of DNA Double Strand Breaks is comparable to diatoms' spontaneous mutation rate.These results should be refined once additional knowledge is acquired about the bioaccumulation of radioelements in the diatoms living in the springs. Additional knowledge is also required on the genome and physiology of diatoms.Finally, the comparison with ERICA, the reference tool for environmental radiation protection, showed that ERICA should be used with great caution when evaluating the radiation exposure of microorganisms in mineral springs. GATE should be seen as the complementary tool to ERICA to characterize, at the micrometric scale, the dose rates to microorganisms in natural ecosystems
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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