1,721,076 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
Spatial and temporal variations in the accumulation and transfer of mercury and methylmercury in Mediterranean plankton food webs
No full textLes populations humaines sont principalement exposées au mercure (Hg) à travers la consommation des produits de la mer. Les poissons méditerranéens contiennent plus de Hg que leurs congénères d’autres zones océaniques, phénomène connu sous le nom “d’anomalie méditerranéenne de Hg”. L’étude de l’accumulation et du transfert du Hg au sein du compartiment planctonique pourrait donc aider à mieux appréhender les phénomènes responsables des fortes teneurs en Hg mesurées dans les prédateurs supérieurs de Méditerranée. Dans ce contexte, le but de cette thèse était d’étudier les variations spatio-temporelles de l’accumulation et du transfert de Hg total (THg) et de monométhylmercure (MMHg) dans les réseaux trophiques planctoniques en Méditerranée.Deux suivis ont été réalisés en Méditerranée, l’un au niveau spatial, et l’autre au niveau temporel impliquant la collecte d’eau et de plancton en grandes quantités, ainsi que la séparation de ce plancton en différentes fractions de taille de phytoplancton (0.7–2.7, 2.7–20, 20–60 et 0.7–60 μm) et de zooplancton (60–200, 200–300, 300–500, 500–1000, 1000–2000 et > 2000 μm). Les rapports isotopiques du carbone et de l’azote, la composition biochimique et les concentrations en THg/MMHg ont été déterminées dans chacune de ces fractions, et la composition du plancton a été identifiée.Le pico- et le nanoplancton, dominants en Méditerranée, bioconcentrent le THg et le MMHg respectivement 106 et 105 fois par rapport aux concentrations dans l’eau de mer. Les cellules picoplanctoniques ont un rapport surface-volume plus important qui favorise la forte bioconcentration de THg. Dans le réseau trophique planctonique, le THg bioréduit, alors que le MMHg bioamplifie et atteint des concentrations maximales dans les niveaux trophiques supérieurs. Au sein des copépodes, le MMHg bioaccumule avec la taille et avec le contenu en protéines des tissus. En condition de biomasses phytoplanctoniques élevées, les concentrations de MeHg dissous dans l’eau de mer et les concentrations en MMHg dans le zooplancton sont plus faibles. Dans ces conditions, la présence de consommateurs herbivores-omnivores réduit la concentration de MMHg dans le zooplancton. En condition de faibles biomasses phytoplanctoniques, les concentrations de MeHg dissous dans l’eau sont plus élevées, ce qui favorise l’absorption directe du MeHg dans le zooplancton. Les consommateurs omnivores-carnivores de niveau trophique plus élevé que l’on retrouve davantage dans ces conditions oligotrophes entraînent une accumulation plus importante de MMHg dans le zooplancton. Les résultats de cette thèse montrent donc que l’accumulation et le transfert de THg et de MMHg dans les réseaux trophiques planctoniques, qui dépendent à la fois de la trophodynamique du milieu et des émissions anthropiques, pourraient en partie expliquer l’anomalie méditerranéenne de Hg.Human populations are mainly exposed to mercury (Hg) through the consumption of seafood. Mediterranean fish contain more Hg than their counterparts in other oceanic zones, a phenomenon known as the 'Mediterranean Hg anomaly'. The study of Hg accumulation and transfer within the planktonic compartment could therefore help towards a better understanding of the phenomena responsible for the high Hg levels measured in Mediterranean top predators. In this context, the aim of this thesis was to study spatio-temporal variations in the accumulation and transfer of total Hg (THg) and monomethylmercury (MMHg) in plankton food webs in the Mediterranean Sea.Two surveys were carried out in the Mediterranean Sea, one at spatial level, the other at temporal level, involving the collection of large quantities of water and plankton, as well as the separation of this plankton into different size fractions of phytoplankton (0.7-2.7, 2.7-20, 20-60 and 0. 7-60 μm) and zooplankton (60-200, 200-300, 300-500, 500-1000, 1000-2000 and > 2000 μm). Carbon and nitrogen isotope ratios, biochemical composition and THg/MMHg concentrations were determined in each of these fractions, as was plankton composition.Pico- and nanoplankton, dominant in the Mediterranean Sea, bioconcentrate THg and MMHg respectively 106 and 105 times higher than the seawater concentrations. Picoplankton cells have a higher surface-to-volume ratio, which favors high THg bioconcentrations. In the plankton food web, THg bioreduces, while MMHg biomagnifies and reaches maximum concentrations in higher trophic levels. In copepods, MMHg bioaccumulates with size and tissue protein content. Under conditions of high phytoplankton biomass, dissolved MeHg concentrations in seawater and MMHg concentrations in zooplankton are lower. Under these conditions, the presence of herbivore-omnivore consumers reduces MMHg concentrations in zooplankton. Under conditions of low phytoplankton biomass, dissolved MeHg concentrations in the water are higher, favoring direct MeHg uptake in zooplankton. The higher trophic level omnivore-carnivore consumers found in these oligotrophic conditions lead to greater accumulation of MMHg in zooplankton.The results of this thesis therefore show that the accumulation and transfer of THg and MMHg in plankton food webs, which depend on both environmental trophodynamics and anthropogenic emissions, could partly explain the 'Mediterranean Hg anomaly'
Dynamic of colored and fluorescent dissolved organic matter in a tropical South Pacific area : climatic and anthropogenic impact
No full textLe lagon de la Nouvelle Calédonie (Pacifique Sud-Ouest), est drainé par les entrées fluviales et océaniques sous la pression de l’érosion des sols ultramafiques (enrichies en Nickel et Cobalt). Le but de cette thèse était de mieux comprendre les sources et la variabilité spatio-temporelle de la matière organique dissoute colorée (MODC) et fluorescente (MODF) le long de continuum rivière-côte-lagon-large en zone lagonaire tropicale du Pacifique dans un contexte de changement climatique et d’anthropisation locale (activité minière). Les côtes Est et Ouest calédoniennes ont été échantillonnées pendant 1 an et demi et pendant la campagne CALIOPE 3 (côte Est) lors d’un épisode El Niño fort (2015-2016), ponctués de forts épisodes pluvieux. L’analyse parallèle factorielle (PARAFAC) des matrices d’excitation-émission de fluorescence (MEEFs) a abouti à l’indentifications de 5 fluorophores : humique-like marin, 2 tyrosine-like, et tryptophane-like d’origine autochtone issus des compartiments phytoplanctoniques et bactériens, et un fluorophore humique-like d’origine allochtone provenant des rivières drainant les côtes. La MODC à 350 et 442 nm suivait une dynamique fortement dépendante des apports fluviaux pouvant être découplée de la dynamique de la MODF. La MODF sur la côte Est suivait un cycle saisonnier (saison sèche/humide) contrairement à la côte Ouest dépendante de d'évènements pluvieux sporadiques. Des fluorophores (humique, tyrosine et tryptophane-like) ont montré des affinités avec certains métaux traces (Nickel, Manganèse, Cobalt) ce qui a permis de développer une expérience de quenching de fluorescence pour déterminer le pouvoir complexant de la MODF naturelle.New Caledonia (South-West Pacific) is a tropical area under strong environmental pressure (climate change and local anthropogenic forcing). The aim of this thesis was to gain a better understanding of the colored (CDOM) and fluorescent (FDOM) dissolved organic matter dynamic in the New Caledonia Lagoon where strong ultramafic erosion pressure is associated with trace metals (i.e., nickel, manganese and cobalt). 3D spectrofluorimetry was used to characterize the CDOM/FDOM. The West and East coasts were sampled during one year and a half in a context of El Niño (2015-2016), interrupted by strong rainy events (storms) and during CALIOPE 3 cruise (East coast). A parallel factor analysis (PARAFAC) of EEMF led to the identification of 5 fluorophores: marine humic-like, 2 tyrosine-like and tryptophan-like peaks (T2 peak) from the biological balance between phytoplankton and bacterioplankton and a terrestrial humic-like from rivers draining caledonian coast. The CDOM signal at 350 and 442 nm had a strong dependency on river inputs accentuated during storms and revealed photodegraded CDOM. The FDOM signal in the East showed a seasonal cycle (wet/dry season) contrary to the West coast depending on sporadic rainy events. Data acquired during the CALIOPE 3 were coupled with trace metal concentrations, biogeochemical parameters, and plankton communities. Some fluorophores displayed a preferential association with nickel and cobalt. The complexation capacities of these fluorophores toward trace metals were revealed by a quenching experiment that allowed to derive complexation constants
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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