1,720,954 research outputs found
Effets des cycles de lemmings sur le succès de nidification d'oiseaux différant par leur taille corporelle et leur comportement
Get PDFRÉSUMÉ: Dans l'Arctique, le succès reproducteur des oiseaux nichant au sol varie généralement de façon importante entre les années. Selon l'hypothèse des proies alternatives, ces fluctuations seraient liées indirectement aux cycles d'abondance de lemmings par le biais de changements dans le comportement et l'abondance des prédateurs partagés. Les dérnonstrations empiriques détaillées de cette hypothèse et des mécanismes impliqués sont toutefois limitées, particulièrement dans l'Arctique canadien. Grâce à un suivi écologique à long terme à l'île Bylot (Nunavut), nous avons étudié les effets des cycles de lemmings sur i) les variations interannuelles du succès de nidification d'oiseaux utilisant différentes stratégies de reproduction (bécasseaux, pluvier bronzé, plectrophane lapon et oie des neiges) et ii) la reproduction et l'abondance estivale de renards arctiques. A l'aide de caméras à déclenchement automatique, nous avons d'abord confirmé que la prédation par les renards arctiques représente la principale cause des échecs de nidification des plectrophanes et des pluviers, observation déjà rapportée chez les bécasseaux et les oies. Pour toutes les espèces d'oiseaux, le taux de survie quotidien des nids et 1a densité de lemmings étaient reliés positivement, mais la force de la relation variait significativenent entre les espèces. Les plectrophanes et les oies étaient beaucoup moins influencés par la densité lemmings comparativement aux pluviers. Ensuite, le succès de nidification des plectrophanes et des oies était relié négativement à la densité de lemmings mesurée l'année précédente.
Considérant que la productivité des renards était liée positivement à la densité de lemmings, ce résultat reflète vraisemblablement la réponse numérique avec délai de la population de renards. Toutefois, les changements d'abondance de renards ne semblaient pas être la principale cause des variations de pression de prédation sur les oiseaux : l'effet avec délai des lemmings sur le succès de nidification était plutôt faible et s'atténuait lors des années de forte abondance de lemmings. Globalement, nos résultats indiquent (l) qu'il existe des différences interspécifiques quant à la force du lien indirect « lemmings-oiseaux » et (2) que la réponse fonctionnelle du prédateur aux fluctuations d'abondance de lemmings semble prédominante pour expliquer cette relation dans l'Arctique canadien. -- Mot(s) clé(s) en français : Limicoles, Oie des neiges, Plectrophane lapon, Arctique, Succès de nidification, Prédation, Interaction trophique, Proies alternatives, Cycles de lemmings, Taux de survie. -- ABSTRACT: In the Arctic, ground-nesting birds usually exhibit reproductive success that varies greatly annually. According to the alternative prey hypothesis, these fluctuations should be linked indirectly to cycles of lemming abundance through changes in abundance and behavior of shared predators. Detailed empirical evidence testing this hypothesis and the underlying mechanisms are nonetheless limited, especially in the Canadian Arctic. Benefiting from a long-term ecological monitoring program on Bylot Island (Nunavut), we investigated the effects of lemming cycles on i) the interannual variation in nesting success of bird species using different reproductive strategies (sandpipers, american golden-plover, lapland longspur and greater snow goose) and ii) the reproduction and the summer abundance of arctic foxes. Using motion-triggered cameras, we first identified predation by arctic fox as the main cause of nest failures for longspurs and plovers, as previously reported for snow geese and sandpipers. For all bird species, daily nest survival rate and lemming density were positively related but the strength of this relationship varied significantly among species. Geese and longspurs were much less affected by changes in lemming density compared to plovers. Moreover, nest success of longspurs and geese was negatively correlated to previous year lemming density.
Considering that fox breeding productivity was positively correlated to lemming density, this result likely reflects the delayed numerical response of the fox population. However, changes in fox abundance did not seem to be the main cause of variation in predation pressure on birds: the delayed effect of lemming density on their nest success was relatively weak and faded in years of high lemming abundance. Overall, our results indicate (l) that there are interspecific differences in the strength of the "lemming-bird" indirect link and (2) that the predator functional response to fluctuations of lemming abundance seems predominant to explain this relationship in the Canadian Arctic. -- Mot(s) clé(s) en anglais : Shorebirds, Snow Goose, Lapland longspur, Arctic, Nest success, Predation, Trophic interaction, Alternative prey, Lemming cycles, Survival rate
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
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
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