1,720,967 research outputs found
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
USING MORPHOMETRICS TO DETERMINE SEX IN A NEOTROPICAL PASSERINE: THE GRAY‐BREASTED WOOD‐WREN (HENICORHINA LEUCOPHRYS)
Get PDFAbstract ∙ Sexual size dimorphism is a widespread pattern among birds, but has remained untested for many Neotropical species. Here we examine sexual differences in a relatively common passerine that is found from Mexico to Bolivia, the Gray‐breasted Wood‐Wren (Henicorhina leucophrys), and provide models to determine the sex of individuals using classical morphometric variables. Measuring 137 museum specimens from five of the 17 recognized subspecies, we describe and test patterns of sexual size dimorphism. Differences between males and females in this sexually monochromatic species were assessed through t‐tests and Logistic Regression Analyses (LRA). Males were larger than females in most measurements for all taxa. Additionally, using univariate LRA models we correctly classified 83–93% of the males and 70–93% of the females using wing length for manastarae and meridana, tail length for tamae and bill length for venezuelensis. All our analyses showed adequate significance and goodness of fit, and models were compared according to their classification percentages and AICc values. We highlight that patterns of sexual dimorphism in this species vary geographically, with some subspecies being more dimorphic than others. To the best of our knowledge, this morphometric research represents the first sex determination assessment for a Neotropical passerine while considering geographic variation, and a first step to describe and understand the patterns of phenotypic variation in this wren species. Resumen ∙ La morfometria como herramienta de determinación del sexo en un paseriforme Neotropical: el Cucarachero Selvático (Henicorhina leucophrys) El dimorfismo sexual de tamaño es común en las aves; sin embargo, no ha sido estudiado en un gran número de especies Neotropicales. En este trabajo examinamos las diferencias sexuales en un paseriforme de amplia distribución que se distribuye desde México hasta Bolivia, el Cucarachero Selvático (Henicorhina leucophrys), y proveemos modelos de determinación del sexo a través del uso de variables morfométricas clásicas. Para describir los patrones de dimorfismo sexual se midieron un total de 137 ejemplares de museo pertenecientes a cinco de las 17 subespecies reconocidas. Evaluamos las diferencias entre machos y hembras de esta especie sexualmente monocromática a través de pruebas t y determinamos los patrones de dimorfismo sexual implementando análisis de Regresión Logística. En todos los taxa los machos presentaron valores mayores que las hembras para la mayoría de las variables. Modelos univariados de Regresión Logística clasificaron correctamente entre 83–93% de los machos y 70–93% de las hembras dentro de cada subespecie, usando largo de ala para manastarae y meridana, largo de cola para tamae y largo de pico para venezuelensis. Los modelos mostraron efectos significativos y valores de bondad de ajuste adecuados, y fueron comparados a través de sus porcentajes de clasificación y valores de AICc. Mostramos que en esta especie los patrones de dimorfismo sexual varían geográficamente, siendo algunas subespecies más dimórficas que otras. Hasta donde sabemos, este estudio aborda por primera vez la determinación del sexo a través de variables morfométricas en un paseriforme Neotropical, considerando su variación geográfica, y representa un primer paso en la caracterización y el estudio de los patrones fenotípicos de esta especie
Variación geográfica, genética y morfológica del Cucarachero Selvático \u3cem\u3eHenicorhina leucophrys\u3c/em\u3e (Aves: Troglodytidae) en Venezuela / Geographic Variation in Mitochondrial and Phenotypical Characters of the Gray-Breasted Wood-Wren \u3cem\u3eHenicorhina leucophrys\u3c/em\u3e (Aves: Troglodytidae) from Venezuela
No full textEl análisis de la variación geográfica de una especie permite determinar el grado de diferenciación entre poblaciones y formular hipótesis sobre su historia evolutiva. El Cucarachero Selvático Henicorhina leucophrys (Aves: Troglodytidae) cuenta con cinco subespecies que se distribuyen en las montañas del norte de Venezuela. Estas subespecies han sido descritas con base en diferencias sutiles de plumaje, cuya variación individual no ha sido evaluada a fondo. En el presente trabajo se caracterizaron los patrones de diferenciación molecular, morfométrico y de plumaje de las poblaciones de H. leucophrys en Venezuela y se contrastaron con la taxonomía actual. En los análisis filogeográficos, basados en ADN mitocondrial (ATP-sintasa 6 y 8), se determinaron siete linajes con una diferenciación genética considerable entre ellos (6–9%), así como patrones de no monofilia para las subespecies H. l. tamae, H. l. meridana y H. l. venezuelensis. Aunque los patrones morfológicos se caracterizaron por una gran variabilidad individual, se encontraron diferencias desconocidas en largos de cola, tarso y pico. Adicionalmente, con el uso de fotografía digital se realizaron análisis colorimétricos, encontrándose diferencias de color en la región ventral y en el patrón de estrías de la garganta entre poblaciones del norte del país (Serranía de Perijá, Cordillera de la Costa) y poblaciones andinas (Tamá, Cordillera de Mérida). Los patrones fenotípicos encontrados no permiten diagnosticar las poblaciones venezolanas de H. leucophrys a nivel subespecífico. Sin embargo, debido al uso de múltiples caracteres este trabajo representa un aporte clave para la sistemática de la especie y el estudio de su diversificación críptica en Venezuela.
The study of geographic variation enables to assess the degree of differentiation between populations and generate hypotheses about their evolutionary history. The Gray-breasted WoodWren Henicorhina leucophrys (Aves: Troglodytidae) has five subspecies that can be found along mountain ranges of northern Venezuela. These taxa have been described based on subtle plumage differences but individual variation within them has not been thoroughly evaluated. In this study we aimed to characterize geographic variation patterns on molecular and classical morphological characters. Our phylogeographic analysis, using two mitochondrial genes (ATPase 6 & 8), showed seven lineages with considerable amount of genetic divergence between them (6-9%), suggesting that at least the subspecies H. l. tamae, H. l. meridana and H. l. venezuelensis are non-monophyletic. Although individual variation was considerable, we revealed unknown significant differences in tail, tarsus and bill lengths. Additionally, using colorimetric analysis with digital photography, we found differences in ventral color and the proportion of streaks of the throat between northern (Serranía de Perijá, Cordillera de la Costa) and Andean populations (Tamá, Cordillera de Mérida). These phenotypical differences are not congruent with current taxonomy, which make diagnosis difficult between Venezuelan subspecies. Nevertheless, our multiple character approach represents a key contribution to the species systematics and the understanding of its cryptic differentiation in Venezuela
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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