1,720,954 research outputs found
Selección de sitios de anidación por el águila real Aquila chrysaetos (Linnaeus, 1758) (Accipitriformes: Accipitridae) en Janos, Chihuahua, México
Full text linkKnowledge about the selection of nesting sites in birds of prey is essential to carry out any management of a population for its conservation. The golden eagle generally chooses rock walls to nest, and this selection is influenced by the natural and anthropic characteristics of the landscape. In Mexico, studying the golden eagle is important because it has a cultural value as a patriotic symbol and biological role regulating its prey populations. In addition, it is listed under the Official Mexican Norm 059-SEMARNAT-2010 in the category of threatened and there is little published scientific information on its ecology and biology in the country. Therefore, this study determined the habitat variables that influence the selection patterns of golden eagle nesting sites in Janos, Chihuahua; for which nesting sites and sites with similar characteristics without the presence of the golden eagle were located for its characterization. The obtained data was analyzed through generalized linear models, taking the presence and absence of nests as the response variable and the habitat characteristics of the sites as predictor variables. Fifteen nesting sites and sixteen sites without nests were located. Of 15 variables measured, there was only a statistically significant difference in the height of the rock walls (W = 44.5, p = 0.003001). The model with the best fit had an AICc value of 20.6, explaining 68% of the variability of the data and includes the variables of height of the rock walls and the roughness of the terrain, the latter being statistically significant (p = 0.0279). Terrain roughness was present in four of the top five candidate models reflecting the importance of topography for nest site selection that can provide isolation from disturbance for eagles.El conocimiento sobre la selección de sitios de anidación en aves rapaces es uno de los factores críticos para realizar cualquier manejo de una población para su conservación. El águila real generalmente elige paredes de roca para anidar, y esta selección está influenciada por las características naturales y antrópicas del paisaje. En México el estudio del águila real es importante debido a que tiene un valor cultural por ser un símbolo patrio y biológico por regular las poblaciones de sus presas, además, se encuentra listada en la Norma Oficial Mexicana 059-SEMARNAT-2010 en la categoría de amenazada y existe escasa información científica publicada sobre su ecología y biología en nuestro país. Por ello, se elaboró un estudio que determinó las variables de hábitat que influyen en los patrones de selección de sitios de anidación del águila real en Janos, Chihuahua. Se buscaron sitios de anidación de águila real y sitios semejantes sin presencia de la especie para tomar los datos de dichas variables; con esta información se analizaron los datos a través de modelos lineales generalizados, tomando como variable de respuesta la presencia y ausencia de nidos y las características del hábitat de los sitios como variables predictoras. Se localizaron 15 sitios de anidación y 16 sitios sin nidos; de 15 variables medidas solo existió diferencia estadística significativa en la altura de las paredes de roca (W = 44.5, p = 0.003001). El modelo con mejor ajuste tuvo un valor de AICc de 20.6, explicando el 68% de la variabilidad de los datos e incluye las variables de altura de las paredes de roca y la rugosidad del terreno, siendo esta última estadísticamente significativa (p =0.0279). La rugosidad del terreno y la altura de la pared de la roca que se presentaron en el mejor modelo reflejando la importancia de la topografía para la selección de sitios de anidación que puede proporcionar aislamiento de perturbaciones para las águilas
Diet of the Golden Eagle during the breeding season in northwestern Chihuahua, Mexico
No full textThe diet of the Golden Eagle (Aquila chrysaetos) was studied in 4 territories in northwestern Chihuahua, México, during the breeding season. Prey remains and pellets were collected from 4 nests during 2014, 2015, and 2016. We identified 12 vertebrate species. Black-tailed jackrabbits (Lepus californicus) were the most important prey remains in terms of frequency (72%) and ingested biomass (86%). We estimated mean prey size to be 1291 g (SE = 3364), indicating that Golden Eagles prey on medium-sized animals (e.g., lagomorphs). The main threats to Golden Eagles are connected to habitat loss and habitat fragmentation, but other factors also affect eagles. We hope our information will help to establish better species management programs.Se estudió la dieta del águila real Aquila chrysaetos durante el periodo reproductivo en el noroeste de Chihuahua, México. Se realizó la colecta de restos de presas consumidas y egagrópilas de los nidos durante 3 temporadas reproductivas (2014, 2015 y 2016) en 4 territorios. Se determinaron 12 taxones de vertebrados, siendo la liebre de cola negra (Lepus californicus) la presa más importante tanto en frecuencia (72%) como en biomasa (86%) en los 4 territorios. Se estimó el MPS global de la región donde se encontraron los territorios (MPS = 1291 g, SE = 3364), indicando que el águila real se alimenta básicamente de presas medianas (e.g. lagomorfos) aunque con un rango amplio en el aporte de biomasa por las presas. Los cambios de hábitat inducidos por el hombre están aumentando enormemente alrededor de los nidos de águila real en la región de estudio en Chihuahua. Recientemente se ha observado una conversion acelerada de pastizales y matorrales hacia tierras de cultivo y para ganadería, por lo que las principales amenazas para las águilas reales se deben a la pérdida y fragmentación del hábitat, además del uso de pesticidas y envenenamiento. Debido a estos cambios, es necesario realizar más estudios ecológicos de las águilas reales en Chihuahua. Esperamos que nuestra información ayude a establecer mejores planes de manejo de la especie
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
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