1,720,955 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
Imagerie de la photosphère des super-géantes rouges : l'origine de la perte de masse
No full textRed supergiants (RSGs) are massive evolved stars that, when they explode as supernovae, enrich the interstellar medium with heavy elements. During the RSG phase, these stars lose part of their mass through stellar winds, and this mass loss affects their subsequent evolution. However, the mechanisms responsible for this mass loss are still poorly understood. Recently, the study of the polarized spectrum of the RSG Betelgeuse allowed the reconstruction of images of the photosphere, and to measure the velocities of convective cells in its atmosphere, unraveling a force that is able to counterbalance gravity at photospheric levels. One of the main goals of this thesis is to identify this force.At the end of 2019, the luminosity of Betelgeuse suddenly dropped, an event known as The Great Dimming, which was associated with an episodic mass-loss event that had occurred several months earlier. In this context, I studied the linear polarization signal of Betelgeuse several months before the Great Dimming, using the Least-Squares Deconvolution technique. By taking advantage of the height of formation of the spectral lines, I studied the linear polarization signal of different layers of the atmosphere of Betelgeuse. I found that, in March 2019, the linear polarization signal in the different layers collapsed, and that this collapse was caused by a local increase in opacity. I linked this increase in opacity to radiation pressure and showed that, under favorable density conditions, the resulting radiative acceleration could be of the same order as the gravitational acceleration. This rise in opacity allowed plasma to be ejected from the star several months before the dimming event. The study of the linear polarization signal thus demonstrated that radiation pressure can counterbalance gravity at photospheric levels and can trigger mass-loss events such as the Great Dimming. In addition to linear polarization, I also studied the bisectors of the intensity profile and showed that, using a simple model with low velocity gradients within a given convective cell, it was possible to qualitatively reproduce the observed bisectors.In addition to the linear polarization profile, this thesis also investigated the intensity profile of Betelgeuse and other RSGs, such as RW Cep. In most RSGs, the intensity profile is narrower than the corresponding linear polarization profile. Using a simple radiative transfer model, I showed that strong velocity gradients along the line-forming region can narrow the integrated intensity profile. The narrow intensity profiles observed in Betelgeuse are caused by such strong velocity gradients, whereas the broad intensity profiles observed in RW Cep and PZ Cas result from weak velocity gradients. The origin of these strong and weak velocity gradients is not yet understood, but they are likely linked to quiescent or active episodes of mass loss.Finally, I studied the variability of Betelgeuse between 2013 and 2019 and showed that it can be explained by typical convective timescales. I found that the smallest convective cells can persist for up to 200 days, while the largest can last up to 330 days. I also analyzed the linear polarization spectrum of the RSG Antares and found that the origin of its linear polarization signal is similar to that of Betelgeuse, enabling me to produce the first images of the surface from spectropolarimetric. These images revealed large convective cells, with radii reaching up to 30% of the stellar radius. In addition, I measured the magnetic field strength, which was on the order of several Gauss, variable over time, and exhibiting polarity reversals.Les étoiles supergéantes rouges (RSGs) sont des étoiles massives évoluées qui, lorsqu'elles explosent en supernova, enrichissent le milieu interstellaire d'éléments lourds. Durant la phase de RSG, ces étoiles perdent une partie de leur masse à travers les vents stellaires, cette perte de masse a une influence sur l'évolution de l'étoile. Cependant, les mécanismes à l'origine de la perte de masse ne sont pas bien connus. Récemment, l'étude du spectre polarisé de la RSG Betelgeuse a permis de produire des images de sa photosphère, ainsi que de mesurer la vitesse des cellules de convection dans l'atmosphère, révélant qu'une force était capable de contrebalancer la gravité aux niveaux photosphériques, et de maintenir le plasma à une vitesse constante. L'enjeu majeur de cette thèse est d'identifier cette force.Fin 2019, la luminosité de Betelgeuse a soudainement chuté, un évènement appelé The Great Dimming, associé à un épisode de perte de masse qui aurait eu lieu plusieurs mois plutôt. Dans ce contexte, j'ai étudié le signal de polarisation linéaire de Betelgeuse grâce à la technique de la déconvolution par les moindres carrés (LSD) plusieurs mois avant le Great Dimmimg. En utilisant la hauteur de formation des raies, j'ai étudié le signal de polarisation linéaire pour différentes couches de l'atmosphère de Betelgeuse. J'ai montré qu'en mars 2019, le signal de polarisation linéaire des différentes couches s'effondrait, et que cet effondrement était du à une augmentation locale d'opacité. J'ai relié l'augmentation d'opacité à la pression de radiation, et j'ai montré qu'avec des conditions de densité favorables, l’accélération radiative est du même ordre de grandeur que l'accélération gravitationnelle. Cette augmentation d'opacité a permis au plasma d'être éjecté de l'étoile plusieurs mois avant le Great Dimming. L'étude du signal de polarisation linéaire a donc permis de mettre en évidence que la pression de radiation était capable de compenser la gravité aux niveaux photosphériques de Betelgeuse, et de déclencher des évènements de perte de masse. En plus du signal de polarisation linéaire, j'ai étudié les bissecteurs du profil d'intensité, et j'ai montré qu'en utilisant un modèle simple faisant intervenir de faibles gradients de vitesse dans une cellule de convection, il était possible de reproduire qualitativement les bissecteurs observés.En plus de l'étude du profil de polarisation linéaire, cette thèse a étudié le profil d'intensité de Betelgeuse et d'autres RSGs comme RW Cep. En effet, le profil d'intensité de la plupart des RSGs est étroit comparé au profil de polarisation linéaire. A l'aide d'un modèle simple de transfert de rayonnement, j'ai montré que la présence de gradients de vitesse le long de la région de formation des raies est capable de réduire la taille du profil d'intensité apparent. Les profils d'intensité étroits observés sur Betelgeuse, et larges sur RW Cep et PZ Cas, sont dus à la présence de forts et faibles gradients de vitesse. La raison de la présence de ces gradients de vitesse n'est pas encore connue, mais est probablement reliée aux épisodes actifs ou passifs de perte de masse des RSGs.Enfin, j'ai étudié la variabilité de Betelgeuse entre 2013 et 2019, et j'ai montré que l'on pouvait expliquer la variabilité de l'étoile avec les temps caractéristiques de la convection. J'ai montré que les plus petites cellules de convection ont un temps de vie de 200 jours et les plus grandes de 330 jours. J'ai également étudié le spectre polarisé de la RSG Antares. J'ai mis en évidence que l'origine du signal de polarisation linéaire était similaire à celle Betelgeuse, me permettant de produire les premières images de la surface d'Antares à l'aide de la spectropolarimétrie. J'ai mis en évidence la présence de larges cellules de convection avec un rayon de l'ordre de 30% du rayon de l'étoile. J'ai aussi mesuré un champ magnétique de quelques Gauss, variable dans le temps et montrant un changement de polarité
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
- …
