1,720,961 research outputs found
Linking predation risk, ungulate antipredator responses, and patterns of vegetation in the high Andes
Get PDFWhether large carnivores indirectly influence vegetation via prey behavior remains controversial because available evidence is largely correlational, and recent field experiments have found weak associations between risk experienced by prey and vegetative responses to herbivory. We combined observational data and a field experiment to test whether an ambush predator—the puma ( Puma concolor )—affected the antipredator behavior of its primary ungulate prey—the vicuña ( Vicugna vicugna )—which in turn had cascading effects on vegetation. We predicted that strong protective effects of pumas on vegetation would be most apparent in habitats where cover and terrain (i.e., physical complexity) facilitated the ambushing strategy of pumas. In 3 different habitats, we evaluated the relationships among predation risk, vicuña behavior, and—by deploying vicuña exclosures—vegetation structure and productivity. We also examined habitat-specific rates of vegetative regrowth. Risky habitats presented high physical complexity, a disproportionately large number of vicuñas killed by pumas, and high relative abundance of pumas. In these habitats, vicuñas displayed strong antipredator behaviors and exclosures did not affect vegetation, suggesting that pumas indirectly protected plants. Conversely, a safe habitat presented low structural complexity, a disproportionately low number of vicuñas killed by pumas, and low relative abundance of pumas. Here, vicuñas relaxed antipredator behaviors and exclosures had strong effects on vegetation. In 1 habitat deemed as risky, however, cascading effects were offset likely because water and nutrients were readily available to plants and regrowth was rapid. Our results show that large ambush carnivores can positively affect vegetation via nonconsumptive effects on their prey, and that these effects are habitat mediated. However, primary productivity modulated the strength of such effects, with high primary productivity dampening the observed cascading effects.Si los grandes carnívoros terrestres afectan indirectamente la vegetación vía cambios en el comportamiento de sus presas es controversial porque la evidencia existente es largamente correlacional, y experimentos de campo recientes encontraron una débil asociación entre el riesgo de depredación y las respuestas de la vegetación a la presión de pastoreo. En este trabajo evaluamos si un depredador de emboscada—el puma ( Puma concolor )—afecta las respuestas antidepredador de su presa principal—la vicuña ( Vicugna vicugna )—con efectos de cascada sobre la vegetación (i.e., graminoides). Predijimos que el efecto protectivo de los pumas sobre la vegetación sería más evidente en hábitats donde la cobertura y el terreno (i.e., complejidad estructural) facilitan la estrategia de emboscada del puma. En tres hábitats diferentes, evaluamos las relaciones entre el riesgo de depredación, el comportamiento de las vicuñas y—mediante la utilización de clausuras—la estructura y productividad de la vegetación. También examinamos tasas de rebrote en cada hábitat. Los hábitats riesgosos presentaron gran complejidad estructural, un número desproporcionadamente alto de vicuñas depredadas por pumas, y una alta abundancia relativa de pumas. En estos hábitats, las vicuñas mostraron fuertes comportamientos antidepredador y las clausuras afectaron levemente la vegetación, sugiriendo que los pumas indirectamente protegen las plantas. Contrariamente, el hábitat definido como seguro presentó poca complejidad estructural, un número desproporcionadamente bajo de vicuñas depredadas por pumas, y una baja abundancia relativa de pumas. Aquí, las vicuñas relajaron sus comportamientos antidepredador y las clausuras tuvieron un fuerte efecto sobre la vegetación. Sin embargo, en un hábitat definido como riesgoso los efectos de cascada fueron neutralizados, probablemente porque el agua y los nutrientes estaban disponibles para las plantas permitiendo un rápido rebrote. Nuestros resultados muestran que los grandes carnívoros pueden beneficiar a los productores primarios vía cambios en el comportamiento de sus presas, y que estos efectos están mediados por el tipo de hábitat. No obstante, la productividad primaria modula la intensidad de estos efectos, con altos niveles de productividad primaria amortiguando los efectos de cascada iniciados por el depredador tope.Fil: Donadio, Emiliano. University of Wyoming, Ecology and Department of Zoology and Physiology; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Buskirk, Steven W.. University of Wyoming, Ecology and Department of Zoology and Physiology; Estados Unido
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
Capturing and radio ear-tagging neonatal vicuñas
Get PDFWe used and evaluated the effectiveness of a hand-capture technique to capture and mark neonatal vicuñas (Vicugna vicugna) at San Guillermo National Park, west-central Argentina. We captured and marked 98 neonates during 5-31 January, 2008-2010. Capture success was 92% (106 attempts), with stationary marking teams being 2.5 times as successful in detecting and capturing neonates as mobile ones. Of neonates captured, 99% were 20 minutes old typically were too mobile to capture. Sex ratio at capture was biased toward males (1.5:1), while mean body weight and neck circumference were similar between sexes. Generally, mothers remained in sight during, and immediately reunited with their neonates after, capture. Four percent of the mothers ran out of sight but then returned, while 2% failed to return. Capture-related mortality was 5%, with maternal abandonment in response to capture activities (n = 3) the leading cause. Ear-tag transmitter had minimal effects on subsequent ear position. The success of our technique likely was based on terrain (flat) and vegetative conditions (short grass), high densities of animals for monitoring (particularly in a meadow), and a predictable, pulsed birth season. This hand-capturing method was efficient for handling and marking neonatal vicuñ as. Combined with the use of ear-tag transmitters, it allows the study of important perinatal processes, including movement and mortality.Fil: Donadio, Emiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. University of Wyoming; Estados UnidosFil: Ruiz Blanco, Cynthia Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Crego, Ramiro D.. Southern Illinois University; Estados UnidosFil: Buskirk, Steven W.. University Of Wyoming; Estados UnidosFil: Novaro, Andres Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Wildlife Conservation Society; Estados Unido
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
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