1,720,953 research outputs found
El rol funcional de la vegetación de zonas áridas y su influencia en procesos eco-hidrológicos bajo un enfoque a diversas escalas.
Full text link"Las zonas áridas representan grandes, complejos y muy diversos ecosistemas que
cubren alrededor del 40% de la superficie terrestre. En general todas las zonas
áridas comparten la característica de ser sitios con altas tasas de
evapotranspiración potencial y una alta heterogeneidad espaciotemporal en la
precipitación, dando como resultado patrones diversos en la cobertura vegetal
presente combinados con espacios de suelo expuesto denominados interespacios.
Esta matriz específica de cobertura vegetal intercalada con interespacios ejerce una
gran influencia sobre los procesos ecohidrológicos tales como la escorrentía y la
infiltración del agua. Por lo tanto se sugiere que la riqueza y diversidad de especies
serán influenciadas por la orientación de la pendiente y ubicación geográfica dentro
del paisaje. De la misma manera la forma en que el paisaje esté estructurado en
interacción con la orientación y topografía influyen en los procesos ecohidrológicos
a nivel de los ecosistemas y comunidades vegetales. El objetivo de este estudio es
examinar el efecto de factores de estado orientación de la pendiente, topografía en
la riqueza de las especies vegetales y en la funcionalidad del paisaje considerando
comunidades dominados por arbustos y gramíneas. A escala de las dos
comunidades dominantes se compararon el efecto de cuatro tipos de parches de
vegetación y tres tipos sin vegetación en procesos ecohidrológicos; esta parte del
estudio se realizó únicamente en las comunidades con orientación de la pendiente
al norte. El estudio se llevó acabo en un rancho privado con pastoreo moderado en
Santo Domingo, San Luis Potosí. La riqueza de las especies vegetales difirió entre
la orientación norte con 26 especies y la sur con 20 especies (P=0.014). El índice
de diversidad fue distinto, considerando las dos orientaciones, 1.25 para el norte y
1.17 para el sur (P=0.002). Mientras que las laderas orientadas hacia el norte
presentaron el doble de número de parches por transecto en la zona dominada por
pastizal que en el matorral, en la orientación sur el efecto fue el opuesto, ahí se
presentaron más parches en la zona dominada por matorral que en la zona
dominada por el pastizal (P=0.0002). Considerando el área de parches, en general
con exposición al norte fue mayor en los matorrales que en los pastizales, y con
exposición al sur mayor en los pastizales que los matorrales (P=0.0002). En los
pastizales, los parches de vegetación formados por gramíneas produjeron menores
tasas de escorrentía (P=0.005) y menos sedimentos (P=0.002) que los
interespacios. Entre los diversos tipos de interespacio, las biocostras retardaron al
doble de tiempo el inicio de la escorrentía (P=0.002) y redujeron significativamente
la tasa pico (P=0.005) y promedio (P=0.001) de escorrentía, así como la producción
de sedimentos (P=0.003) sobre micrositios de suelo desnudo o de suelo con
fragmentos de roca. En la comparación del funcionamiento de todos los parches a
nivel de especies, la especie nativa Buchloe dactyloides presentó consistente y
significativamente respuestas eco hidrológicas diferentes, retardó el inicio de la
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escorrentía (P=0.002) redujo las tasas pico (P=0.002) y promedio (P=0.001) de
escorrentía, presentó una mayor infiltración de agua (P=0.003) y menor pérdida de
suelos (P=0.002) comparado con la especie exótica Melinis repens y las arbustivas
Dalea bicolor y Mimosa aculeaticarpa. Los esfuerzos de monitoreo sirven para
examinar el efecto de la vegetación en la funcionalidad del paisaje. Los resultados
confirman que un potencial manejo de ganado debería buscar incrementar el
número y área de los parches de la especie Buchloe dactyloides y que las costras
biológicas de suelo prevalecen en los interespacios. Un análisis funcional del paisaje
a escala local y topográfica permitió entender el papel de arbustos y gramíneas en
procesos ecohidrológicos.""Drylands represent vast, complex and diverse ecosystems covering 40% of the global land mass. All drylands have two fundamental characteristics in common: high rates of evapotranspiration and high spatiotemporal heterogeneity in precipitation, together generating discontinuous vegetation cover and areas of open vegetation-free soil called interspaces. This open vegetation structure and specific cover types of interspaces may greatly influence ecohydrological processes such as infiltration in dryland ecosystems. Hence, in dryland landscape with pronounced topography the number and size of vegetation patches together with interspace characteristics determine distinct dryland hydrological functional responses. The objective of this study was to examine the effects of the state factors orientation and topography on the richness of plant species and on the functionality of landscapes considering pant communities dominated by shrubs and grasses. At the scale of two plant community types, we compared the effect of four vegetation patch types and three interspace microsites on ecohydrological processes; this aspect of the study was only conducted in the north-exposed plant communities. This study was conducted in a private rangeland with moderate grazing in Santo Domingo, San Luis Potosi. Species richness differed between North (26) and South (20) exposed slopes (P= 0.014); also the diversity index differed with 1.25 in the North and 1.17 in the South slopes (P= 0.002). While N-exposed slopes presented twice as many vegetation patches per transect in grasslands than shrub-dominated communities, S-exposed slopes presented more patches in shrub-dominated communities than in grasslands (P=0.0002). Patch area, however was larger in N-exposed shrublands than grasslands and larger in S-exposed grasslands than shrublands (P=0.0002). Grass patches produced lower runoff rates (P=0.005) and less sediment (P=0.002) than their associated interspaces. Among all interspace types, biocrusts clearly slowed down the initiation of runoff (P=0.002), reducing the maximum (P=0.005) and average (P=0.001) rates of runoff and sediment production (P=0.003) compared to bare soils and rocky soils. Comparing the functionality of vegetated patches, patches covered with the native species Buchloe dactyloides significantly delayed the beginning of runoff (P=0.002), reduced the peak (P=0.002) and average (P=0.001) amount of runoff as well as favoring the local water budget by allowing greater depths of infiltration (P=0.003) and less soil losses (P=0.002) compared to other species present on the site. The exotic species Melinis repens although physiologically and morphologically similar to Buchloe dactyloides exhibited hydrological responses comparable with Mimosa aculeaticarpa and Dalea bicolor, the dominating shrub species in the landscape. Careful monitoring efforts serve to examine the effects of the vegetation on landscape functionality. Our results confirm that potential adaptive management of livestock should aim at increasing patch number and area of Buchloe dactyloides and by reclaiming open interspace areas with biocrust. A landscape level functional analysis including local scale and topographic aspects, allows relating the role of shrubs and grasses in ecohydrological processes.
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
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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