1,721,075 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
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
The biogeochemical silicon cycle in the Southern Ocean tracked by isotopic approaches
No full textLa biogéochimie de l’Océan austral joue un rôle crucial dans la régulation de la production primaire marine globale en contrôlant la disponibilité des nutriments dans les eaux de surface des basses latitudes. Les variations du cycle du silicium (Si) sont nombreuses et son couplage avec les autres éléments n’est pas encore bien compris dans cet océan. Les résultats issus de deux approches isotopiques différentes suggèrent qu’une pompe de Si active est rapidement initiée au printemps par la transition d’un mode de production de silice biogénique régénéré à une production dite « nouvelle ». L’évolution saisonnière de la composition isotopique naturelle du Si (δ30Si) est principalement contrôlée par l’équilibre entre les rapports « dissolution/production » et « Si-supply/Si-uptake » qui découplent la dynamique isotopique des réservoirs de Si dissout et particulaire (respectivement DSi et BSi). Nous avons également utilisé les mesures de δ30Si pour retracer les flux saisonniers de BSi vers l’océan profond. Ces résultats confirment que le δ30Si n’est pas altéré durant la sédimentation des particules. L’évolution saisonnière du δ30Si a permis de quantifier pour la première fois certains processus contrôlant la production des diatomées et leur devenir, tels que les évènements de mélange alimentant la ML en nutriments, ou l’évolution saisonnière de la vitesse de sédimentation des particules. Ces résultats confirment que le δ30Si du DSi et de la BSi, combinés aux techniques isotopiques de mesure des flux dans la ML, sont des outils prometteurs dans l’amélioration de nos connaissances du cycle du Si et apportent des informations nouvelles à intégrer aux modèles biogéochimiques.Southern Ocean biogeochemistry plays a crucial role on global marine primary production by impacting the nutrient availability even in low latitude surface water. Variations in the silicon (Si) cycle are large and its coupling to other nutrient biogeochemical cycles is still not well understood in this ocean. Results of two different isotopic approaches suggested that a strong silicon pump was quickly initiated in spring by a switch from regenerated to new biogenic silica production. The seasonal evolution of natural Si isotopic composition (δ30Si) was mainly driven by the balance between the “dissolution to production” and “Si-supply to Si-uptake” ratios that decoupled the isotopic dynamics of particulate and dissolved Si-pools (DSi and BSi, repectively). We also used δ30Si measurements to track seasonal flows of BSi to the deep sea with. These results confirmed that the δ30Si is well preserved during particles settling. The seasonal evolution of δ30Si signal allows for the first time to quantify important features about the processes controlling the diatoms’ productivity and its fate, such as mixing events that bring nutrient in the ML or the seasonal evolution of particles sinking velocities. These insights confirm that the δ30Si of DSi and BSi, combined to isotopic technics to measure Si fluxes in the ML, are promising tools to improve our understanding on the Si-biogeochemical cycle and provide new constraints for application to biogeochemical models
Biogeochemical cycle of silicon from the Subtropical to Antarctic zones along the GEOTRACES GS02 Section (South-West Indian Ocean, SWINGS)
No full textLe silicium (Si) est un élément clé pour la silicification des organismes marins. Sous forme d'acide silicique (DSi), Si contrôle la production des diatomées, qui représente le phytoplancton prédominant dans l'océan Austral. Les diatomées vont synthétiser de la silice biogénique (BSi) et sont des acteurs clés des pompes biologiques à carbone et à silicium qui sont particulièrement actives dans l'océan Austral, notamment au niveau des zones naturellement fertilisées en fer. Afin de mieux quantifier et comprendre les processus en jeu, nous utilisons les signatures des isotopes stables de Si (δ30Si). En effet, les diatomées assimilent préférentiellement les isotopes légers, alourdissant ainsi le stock DSi dans les eaux environnantes. Ces signatures isotopiques apportent des informations sur les processus de surface et permettent de suivre les mélanges profonds de DSi. Dans cette thèse, les compositions isotopiques de Si sont combinées à plusieurs paramètres : les concentrations DSi, BSi, de silice lithogène (LSi), les observations de particules en suspension et les analyses de pigments. Cette thèse s'inscrit pleinement dans les objectifs du programme GEOTRACES en se concentrant sur l'intégralité du transect SWINGS et sur toute la colonne d'eau. Cette campagne a permis d'échantillonner différentes provinces contrastées à la fin de l'été austral 2021 (janvier-février) : (i) la zone subtropicale (STZ) en passant par la marge sud-africaine, (ii) la Zone du Front Polaire (PFZ) en passant dans l'environnement des îles Prince Edward, Marion, Crozet et Kerguelen, (iii) la zone Antarctique (AZ) en passant au niveau du plateau nord de Kerguelen, notamment autour des îles volcaniques Heard et McDonald. Nos résultats montrent l'importance des zones de plateau sur le cycle de Si, en particulier le plateau nord de Kerguelen qui est le lieu d'une dissolution intense de matériel lithogénique, que nous avons estimée à 3,7±2,3×106mol.km-2.an-1 grâce à un bilan de masse des isotopique pour les zones peu profondes (<100m) autour des îles Heard et McDonald. Cette estimation permettrait de mieux quantifier les flux de dissolution de LSi à l'échelle globale. La STZ de l'océan indien sud, jusque-là encore jamais étudiée avec les compositions isotopiques de Si, est caractérisée par une utilisation du réservoir DSi relativement modérée, même si les concentrations en DSi, inférieures à 2µmol.L-1, impliquent une faible production de BSi. Cela suggère une limitation principale des diatomées par d'autre(s) nutriment(s) que DSi, probablement l'azote. Ainsi nos données isotopiques de DSi montrent qu'en surface et subsurface, les eaux contenant le moins de DSi ne sont pas nécessairement plus lourdes ce qui met en évidence la complexité des processus de surface. De plus, sur l'ensemble du transect, une faible variation isotopique de BSi avec la profondeur est observée, cohérente avec la surface. Par ailleurs, nous avons mesuré les compositions isotopiques de BSi dans différentes tailles de classe et montré que dans la grande majorité des cas, il n'y a pas de différence significative. Ceci confirme un effet d'espèce négligeable sur les compositions isotopiques de BSi lorsqu'elles sont mesurées sur des échantillons océaniques. Enfin, nous avons reconstruit les signatures de DSi profondes, à partir d'une approche originale, basée sur une analyse paramétrique multivariée optimale (OMPA). Excepté au niveau des marges, et certaines zones proches des plateaux comme Kerguelen, les signatures isotopiques de DSi sont quasi-conservatives. Elles peuvent être expliquées uniquement par des mélanges de masses d'eau, et ce, même dans des zones de forte dissolution de DSi. Ce caractère quasi-conservatif du δ30SiDSi permet de caractériser et quantifier les contributions isotopiques en DSi de chaque masse d'eau présente. Cette nouvelle approche, par l'OMPA, est prometteuse, elle permettrait de mieux interpréter les signatures profondes de Si et d'enrichir les modèles existants.Silicon (Si) is a key element in the silicification of marine organisms. In the form of silicic acid (DSi), Si controls the production of diatoms, the predominant phytoplankton in the Southern Ocean. Diatoms synthesise biogenic silica (BSi) and are key players in the biological carbon and silicon pumps that are particularly active in the Southern Ocean, especially in areas that are naturally fertilised with iron. To better quantify and understand the processes involved, we are using the signatures of stable Si isotopes (δ30Si). This is because diatoms preferentially assimilate light Si isotopes, thereby leaving the DSi stock isotopically heavier in the surrounding waters. These isotopic signatures provide information on surface processes and make it possible to monitor deep Si mixing. In this thesis, Si isotopic compositions are combined with several parameters: DSi, BSi and lithogenic silica (LSi) concentrations, observations of suspended particles and pigment analyses. This thesis is fully in line with the objectives of the GEOTRACES programme, focusing on the entire SWINGS transect and on the entire water column. This campaign has made it possible to sample different contrasting provinces at the end of the austral summer of 2021 (January-February): (i) the Subtropical Zone (STZ) including the South African margin, (ii) the Polar Front Zone (PFZ) including the environment of the Prince Edward, Marion, Crozet and Kerguelen islands, (iii) the Antarctic Zone (AZ) including the northern plateau of Kerguelen, notably around the volcanic Heard and McDonald islands. Our results show the importance of plateau areas on the Si cycle, in particular the northern Kerguelen plateau, which is the site of intense dissolution of lithogenic material, which we estimated at 3.7±2.3×106 mol km-2 yr-1 using a mass balance of Si isotopes for the shallow areas (<100m) around the Heard and McDonald islands. This estimate would help to better constrain the quantification of LSi dissolution fluxes on a global scale. The STZ of the southern Indian Ocean, never studied before with Si isotopic compositions, is characterised by relatively moderate use of the DSi reservoir, even though DSi concentrations of less than 2 µmol L-1 implying low BSi production. This suggests that the diatoms are mainly limited by nutrient(s) other than DSi, probably nitrogen. Hence, our DSi isotope data show that at the surface and subsurface, water containing the least DSi is not necessarily heavier, which highlights the complexity of surface processes. In addition, over the whole transect, a low isotopic variation of BSi with depth was observed, coherent with surface signatures. Moreover, we measured the BSi isotopic compositions in different class sizes and showed that in the vast majority of cases there was no significant difference. This confirms a negligible species effect on BSi isotopic compositions when measured on samples taken from the ocean's mixed layer. Finally, we reconstructed the deep DSi signatures using an original approach based on an optimal multivariate parametric analysis (OMPA). With the exception of the margins and certain areas close to the shelves, such as Kerguelen, the isotopic signatures of DSi are quasi-conservative. They can be explained entirely by mixing of water masses, even in areas of high DSi dissolution. This quasi-conservative nature of δ30SiDSi makes it possible to characterise and quantify the DSi isotopic contributions of each water mass present. This new approach, using OMPA, is promising, as it will enable us to better interpret deep Si signatures and enhance existing models
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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