1,720,960 research outputs found
Tracing eye color evolution in pipridae: A quantitative approach using public photo databases
No full textIlustraciones, gráficas,Las aves exhiben una amplia gama de colores de ojos, sin embargo, los mecanismos que impulsan esta variación siguen siendo poco estudiados. Este estudio analiza cuantitativamente el color de ojos en la familia Pipridae, utilizando imágenes de alta resolución de bases de datos públicas. Obtuvimos y procesamos datos de color RGB de 55 especies de salatarines utilizando la distribución Fiji de ImageJ, enfocándonos en valores medianos para minimizar efectos de valores atípicos. Se compararon tres métricas de resumen (media, media ponderada y mediana), revelando resultados consistentes y demostrando la robustez de nuestra metodología. Aplicamos técnicas de reconstrucción del estado ancestral para rastrear la evolución del color de ojos dentro de Pipridae. Se realizaron reconstrucciones ancestrales discretas y continuas. Nuestros hallazgos indican que los Pipridae ancestrales probablemente tenían ojos de tonos intermedios a oscuros, con múltiples evoluciones independientes hacia colores más claros dentro del clado Piprinae. Este estudio proporciona un enfoque cuantitativo confiable para estudiar la variación y evolución del color de ojos en aves, demostrando su aplicabilidad a otros taxones. Los resultados se alinean a veces y desafían la literatura existente, destacando el potencial del método para revelar nuevos patrones de evolución del color de ojos en aves. Se requieren más investigaciones y recopilación de datos para comprender completamente los impulsores de estas variaciones de color.Birds exhibit a broad spectrum of eye colors, yet the mechanisms driving this variation remain understudied. This study quantitatively analyzes eye color across the Pipridae family, leveraging high-resolution images from public databases. We obtained and processed RGB color data from 55 manakin species using the Fiji distribution of ImageJ, focusing on median values to minimize outlier effects. Three summary metrics (mean, weighted mean, and median) were compared, revealing consistent results and demonstrating the robustness of our methodology. We applied ancestral state reconstruction techniques to trace eye color evolution within the Pipridae. Discrete and continuous ancestral reconstructions were performed, converting RGB data to the HSL color space for luminance analysis. Our findings indicate that ancestral Pipridae likely had intermediate to dark eyes, with multiple independent evolutions towards lighter colors within the core manakins. This study provides a reliable quantitative approach for studying eye color variation and evolution in birds, demonstrating its applicability to other taxa. The results align with and sometimes challenge existing literature, highlighting the method’s potential to reveal new avian eye color evolution patterns. Further research and data collection are necessary to understand these color variations' drivers fullyIntroduction / Methods / Results / Discussion / ReferencesUniversitarioBiólogo(a
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
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
Avian Eye Color, Phylogeography, and the Genetics of Iris Variation in Grackles (Quiscalus)
No full textBirds display a rainbow of eye colors, but this trait has been relatively little-studied. In this dissertation, I first survey eye color variation across birds and discuss its causes at three levels: mechanistic, genetic and evolutionary (Chapter 2). Then, I examine the evolutionary history of the Cassidix grackle complex, a clade that includes notable inter- and intra-specific variation in eye color, and I address questions about phylogeography and hybridization within the group (Chapter 3). Finally, I focus on Boat-tailed Grackles (Quiscalus major), which show geographic and within- population variation in eye color. I combine whole-genome sequencing and phenotypic data from field photographs to quantify eye color variation within Q. major and identify regions of the genome associated with eye color differences (Chapter 4).
In Chapter 2, I summarize the patterns of variation in eye color across birds, the pigments and structures that give bird irises their colors, the small number of genes that have been linked to eye color in domestic birds, and the evolutionary hypotheses relating eye color to both survival and signaling.
In Chapter 3, I conducted a phylogeography study using samples from all 13 subspecies of the three species in the Cassidix clade: Boat-tailed Grackle (Q. major), Great-tailed Grackle (Q. mexicanus), and the extinct Slender-billed Grackle (Q. palustris). I find no evidence of admixture between Q. major and Q. mexicanus, and find support for the monophyly of both species, contrary to evidence from mitochondrial DNA. I also show that geographic breaks, not eye color differences, structure genetic variation within Q. major.
Lastly, in Chapter 4, I took standardized eye photos of 41 Boat-tailed Grackles collected in Louisiana, Mississippi, and Alabama, and sequenced whole genomes of each individual. I used FST outlier scans to find regions of the genome that differ between light-eyed and dark-eyed individuals of the species. I then identified a set of candidate genes that may underlie eye color variation in Q. major, including some, such as KCNJ13, that have been implicated in pigmentation in other vertebrates
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