1,720,968 research outputs found
Ecología no reproductiva de la reinita rayada (Setophaga striata) en Colombia
Get PDFMapas, Fotografías, GraficasLa reinita rayada (Setophaga striata) es un ave migratoria Neártica-Neotropical que está declinando rápidamente, que se reproduce en el bosque boreal de Norte América y migra a Sur América durante su época no reproductiva. Similar a otras especies de migratorias, diferentes factores contribuyen a la disminución de sus poblaciones, como la pérdida de hábitat en los sitios no reproductivos. Actualmente, la información sobre la ecología de S. striata en los sitios no reproductivos es escasa, no hay información demográfica, ni de uso para diferentes hábitats en los sitios no reproductivos. En este estudio, queremos contribuir al conocimiento del nicho ecológico y ecología no reproductiva de S. striata en Colombia a través de las siguientes preguntas: 1) ¿Cómo varían las tasas de ocupación de S. striata a escala regional y local a través del rango no reproductivo en Colombia? 2) ¿Cuáles son las características de la vegetación (estructura del hábitat a escala fina) asociadas con la ocupación de S. striata en sistemas agroforestales (cítricos, cacao y silvopastoril y bosque? 3) ¿Cuál paisaje (exurbano vs rural) y hábitat (cítricos vs cacao con sombrío) tiene mejor calidad usando fidelidad al sitio, supervivencia y uso de hábitat para S. striata en la región del Orinoco? Es la primera investigación a escala múltiple sobre S. striata en las regiones de la Orinoquia y la Amazonia de Colombia, y que podría contribuir a posibles acciones de conservación.The Blackpoll Warbler (Setophaga striata) is a rapidly declining Nearctic-Neotropical migratory bird that breeds across the boreal forest of North America and migrates to South America during its non-breeding period. Similar to other migratory species, several factors may be contributing to population declines, including habitat loss and degradation on the non-breeding grounds. Currently, information about the ecology of Blackpoll Warblers on their non-breeding grounds is scarce and no demographic information for different non-breeding habitats exists to date. In this study, we will contribute to the knowledge of the ecological niche and non-breeding ecology of the Blackpoll Warbler in Colombia, by addressing the following questions: 1) How do occupancy rates and abundance vary at multiple scales (i.e., regional, landscape, and local) across the Blackpoll Warblers over-wintering range in Colombia?, 2) How does space use and home range size of Blackpoll Warblers vary across different scales?, 3) Do exurban or rural landscapes represent habitats of higher quality for Blackpoll Warblers based on estimations of apparent survival in the Orinoco region? This is the first multi-scale investigation of Blackpoll Warbler in Colombia's Orinoco and Northern Amazon regions, and that could contribute to potential conservation actions.Funding was provided by Environment and Climate Change Canada through an operating grant by Keith.A.Hobson., from Western University, London, Canada, and Phil.Taylor from Acadia University. Project and fieldwork was carried out under an agreement between SELVA and Universidad de Los Llanos (no. 053, 2017 and no.29, 2021)DoctoradoDoctor en Estudios AmazónicosEcosistemas, Biodiversidad y Conservació
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
Origin and dynamics of a hybrid zone between Ramphocelus tanagers (Thraupidae) in Colombia
No full textCharacterizations of hybrid zones are of importance in evolutionary biology because they can give insights about the characters and processes implied in population divergence. Here, we characterize a hybrid zone between tanagers in the genus Ramphocelus (Thraupidae) located in Western Colombia. We tested whether this hybrid zone originated as a result of secondary contact or of primary differentiation, and described its dynamics across time using molecular, morphological, and plumage coloration data in combination with palaeodistribution modeling. Models of potential historical distributions based on climate data and genetic signatures of population expansion suggest that the hybrid zone originated following secondary contact between two populations that expanded their ranges out of isolated areas in the Quaternary. Concordant patterns of variation in phenotypic characters across the hybrid zone and its narrow extent are suggestive of a tension zone, maintained by a balance between dispersal and selection against hybrids. Comparisons between historical and current specimens suggest the zone has moved towards the east, possibly as a result of sexual selection or of asymmetric gene flow.Magíster en Ciencias BiológicasMaestrí
Origin and dynamics of a hybrid zone between Ramphocelus tanagers (Thraupidae) in Colombia
No full textCharacterizations of hybrid zones are of importance in evolutionary biology because they can give insights about the characters and processes implied in population divergence. Here, we characterize a hybrid zone between tanagers in the genus Ramphocelus (Thraupidae) located in Western Colombia. We tested whether this hybrid zone originated as a result of secondary contact or of primary differentiation, and described its dynamics across time using molecular, morphological, and plumage coloration data in combination with palaeodistribution modeling. Models of potential historical distributions based on climate data and genetic signatures of population expansion suggest that the hybrid zone originated following secondary contact between two populations that expanded their ranges out of isolated areas in the Quaternary. Concordant patterns of variation in phenotypic characters across the hybrid zone and its narrow extent are suggestive of a tension zone, maintained by a balance between dispersal and selection against hybrids. Comparisons between historical and current specimens suggest the zone has moved towards the east, possibly as a result of sexual selection or of asymmetric gene flow.Magíster en Ciencias BiológicasMaestrí
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
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