1,720,953 research outputs found
Mosaico geográfico de las comunidades de artrópodos visitadores de las flores de Myrtillocactus geometrizans (Cactaceae) en respuesta a la variabilidad genética, características del ambiente y morfología floral
Get PDFLa coexistencia de las especies varía a lo largo de gradientes geográficos y ambientales. En cada sitio las poblaciones se enfrentan a variaciones bióticas relacionadas a la dinámica poblacional, como migración, extinciones locales, fauna local o tipo de vegetación y abióticas como precipitación o perturbación. Estos factores influyen en la distribución y características de las especies que se adaptan localmente como resultado de su estructura y ecología. Las interacciones entre especies eventualmente forman distintos ensamblajes y las adaptaciones en redes locales establecen diferentes configuraciones formando un mosaico geográfico de especies con sus interacciones. Particularmente las interacciones planta-animal desempeñan un papel fundamental en los ecosistemas. Específicamente los artrópodos que visitan las flores están relacionados con la adecuación de la planta. Myrtillocactus geometrizans es una cactácea endémica y de amplia distribución en México, se desarrolla en matorral xerófilo y selva baja caducifolia, presenta un periodo de floración que coincide con el de pocas especies de cactáceas, lo que la hace ser uno de los pocos recursos disponibles para un gran número de artrópodos durante ese periodo. Se ha reportado que M. geometrizans tiene diversas interacciones con artrópodos como, mutualismo, depredación, parasitismo y parasitoidismo. Por lo que M. geometrizans se enfrenta a factores que pueden generar un mosaico geográfico en sus poblaciones. La pregunta de investigación es ¿Cómo la estructura de la comunidad de artrópodos visitantes de las flores de diferentes poblaciones de M. geometrizans forman un mosaico geográfico influenciado por el tipo de vegetación, el nivel de perturbación, la morfología floral y la diversidad genética de las plantas? Se evaluaron cuatro localidades ubicadas en las Reservas de la Biosfera de Tehuacán-Cuicatlán y Barranca de Metztitlán, en selva baja caducifolia y matorral xerófilo. Se estimó la diversidad genética de las plantas con el intrón petB, el índice de disturbio con el procedimiento propuesto por Martorell y Peters, se comparó la morfología floral con la evaluación de 14 variables florales y se caracterizó a la comunidad de artrópodos que llegan a las flores con claves taxonómicas y con la diversidad verdadera. Se encontraron similitudes entre sitios de la misma Reserva de la Biósfera. Los sitios menos perturbados se encontraron en la Reserva de la Biosfera de Tehuacán-Cuicatlán. En esos sitios se registraron los valores más bajos de diversidad genética. Las flores más grandes, pero con menor cantidad en estructuras florales. Los sitios de la Reserva de la Biosfera de Metztitlán fueron casi 100 veces más perturbados que los ubicados en Tehuacán-Cuicatlán. Tuvieron los valores de diversidad genética más altos. Las flores más chicas, pero con mayor cantidad de estructuras florales. Por otro lado, las comunidades de artrópodos no mostraron estos patrones de similitud por Reservas de la Biósfera si no por tipo de vegetación. Los matorrales xerófilos tuvieron las comunidades de artrópodos más diversas. Contrario a lo que se esperaba los sitios más perturbados no presentaron perdida de la diversidad genética o de la diversidad de artrópodos. Además, las flores más grandes no fueron las más atractivas para los artrópodos. El mosaico geográfico de las comunidades de artrópodos que visitan las flores de M. geometrizans estuvo determinado por los valores más altos y bajos de las condiciones estimadas en este estudio. Tuvo una influencia relacionada a la diversidad genética de las poblaciones del garambullo, de la cantidad de estructuras florales y de la perturbación antropogénica local. Palabras clave: Garambullo, visitantes florales, matorral xerófilo, selva baja caducifolia, disturbio antrópico.Species coexistence varies along geographic and environmental gradients. In each site, populations face to biotic variations related to population dynamics, such as migration, local extinctions, local fauna or vegetation type, and abiotic variations such as precipitation or disturbance. These factors influence the distribution and in species characteristics that adapt locally as a result of their structure and ecology, therefore, their diversification is a geographical process. The interactions eventually expand, what started as a pairwise interaction becomes a geographic mosaic of species with punctual interactions, distinct assemblages, and evolution in local networks of different phylogenetic configurations. Particularly plant-animal interactions play a fundamental role in ecosystems. Specifically, the arthropods that visit the flowers are related to the fitness of the plant. Myrtillocactus geometrizans is an endemic cactus with wide distribution in Mexico, it develops in xerophytic scrub and tropical deciduous forest, it has a flowering period that coincides with that of few species of cacti, which makes it one of the few resources available for a large number of arthropods during that period. It has been reported that M. geometrizans has various interactions with arthropods such as mutualism, predation, parasitism and parasitoidism. Therefore, M. geometrizans faces factors that can generate a geographic mosaic in its populations. The research question is how does the community structure of flower-visiting arthropods from different populations of M. geometrizansform a geographic mosaic influenced by the level of disturbance, floral morphology, and plant genetic diversity? Four locations located in the Tehuacán-Cuicatlán and Barranca de Metztitlán Biosphere Reserves, in tropical deciduous forest and xerophytic scrub, were evaluated. The genetic diversity of the plants was estimated with the petB intron, the disturbance index with the procedure proposed by Martorell and Peters, the floral morphology was compared with the evaluation of 14 floral structures and the flowers’ visitors arthropods community was characterised with taxonomic keys and with true diversity. Si milarities were found between sites in the same Biosphere Reserve. The least disturbed sites were in TehuacánCuicatlán Biosphere Reserve. The lowest values of genetic diversity were recorded at those sites. The largest flowers, but with fewer floral structures. Sites in the Metztitlán Biosphere Reserve were nearly 100 times more disturbed than those located in Tehuacán-Cuicatlán. They had the highest genetic diversity values. The smallest flowers, but with a greater number of floral structures. On the other hand, the arthropod communities did not show these patterns of similarity by Biosphere Reserves, but rather by vegetation type. Xerophytic scrubs had the most diverse arthropod communities. Contrary to what was expected, the most disturbed sites did not present loss of genetic diversity or diversity of arthropods. In addition, the largest flowers were not the most attractive to arthropods. The geographic mosaic of the arthropod communities that visit the flowers of M. geometrizans was determined by highest and lowest values of the conditions estimated in this study. It had an influence related to the genetic diversity of the garambullo populations, the number of floral structures and the local anthropogenic. Keywords: Garambullo, arthropod visitors, anthropogenic disturbance, functional groups, tropical deciduous forest, xerophilous scrub
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
- …
