1,720,958 research outputs found
Evaluating Productivity, Nesting Success, and Conservation of Thick -Billed Parrots.
Get PDFI studied the breeding activity, productivity and nesting success of the Thick-billed Parrot (Rhynchopsitta pachyrhyncha) during a 3-year period 1997--1999, and also analyzed preliminary data from 1995 and 1996. I studied the Parrots in six nesting areas located in the Sierra Madre Occidental in Mexico. Data were collected on breeding areas characteristics, nest site characteristics, reproductive activity, productivity, and nesting success. Most of the historical breeding range reported in the literature was searched for nests. Two main breeding areas reported in the literature continue to be the major breeding strongholds for the species. Cebadillas and Madera accounted for 56% and 18% of the nests respectively. I assessed reproductive success of 123 accessible nests. Overall, 81.3% of the nests were successful. Of 337 eggs followed, 268 hatched (79.5%) and 200 chicks fledged (74.6%). In the 5-year period, clutches averaged 2.73 and 1.62 young parrots fledged/nest. Except 1999, nesting success and fledging success were high with rates above 80%. Causes of total nest loss included: nest desertion, mammal predation, and parasite infestation. During the study, nests were found in 187 trees and snags of seven tree species. Nests occurred preponderantly in snags (58.8%). Nests averaged 75.2 cm diameter at breast height (dbh), and only 2 nests out of the total of 187 were in trees under 40 cm. dbh. Most nests occurred in Douglas fir (32.6%), and Mexican white pine (21.9%). Most nests occurred in areas with high densities of large trees and snags ≥60 cm (dbh). Nesting persisted in areas under commercial harvest, but trees and snags used for nesting were frequently logged and many nest sites were lost. Decline of the species seems to be related to large-scale logging of historical breeding and wintering range. Timber harvesting affects nest site availability in breeding areas and food supply in breeding and wintering areas. Life history traits of the species seem to enable the parrots to cope with cyclic and sometimes unpredictable food supply. High reproductive performance seems to occur in years with evidence of abundant food supply
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
USE OF PHYLOGENETIC ANALYSIS TO IDENTIFY EVOLUTIONARILY SIGNIFICANT UNITS FOR THE ORANGE-FRONTED PARAKEET (EUPSITTULA CANICULARIS) IN MEXICO
Get PDFIn avian conservation biology, the subspecies concept based on reciprocal monophyly has been successfully applied to define priority populations through Evolutionarily Significant Units (ESUs). In México, the Orange-fronted Parakeet (Eupsittula canicularis) ranks first in illegal parrot trade. Its distribution ranges from southern Sonora to Chiapas on the Pacific slope, with populations representing three subspecies: E. c. canicularis, E. c. eburnirostrum, and E. c. clarae. To identify and propose ESUs to assist in conservation proposals for different populations, we assessed subspecific reciprocal monophyly via phylogenetic analyses and haplotype networks based on the mitochondrial DNA genes cytochrome oxidase I y NADH dehydrogenase 2. Feather and blood samples from specimens collected from nests in 2005 and 2007 were used. A total of five specimens of E. c. eburnirostrum from two localities in the state of Michoacán and four specimens of E. c. clarae from the state of Sinaloa were analyzed and no specimens of E. c. canicularis were included. The analyses included sequences obtained by us and those previously reported for E. aurea, E. cactorum, E. canicularis, E. nana, and E. pertinax. Both the phylogenetic analyses and haplotype networks suggest two groups that correspond to two subspecies of E. canicularis based on morphological and geographical evidence. Therefore these two subspecies are proposed as independent ESUs for conservation purposes
DEMOGRAPHIC HISTORY OF THE ORANGE-FRONTED PARAKEET (EUPSITTULA CANICULARIS) IN MEXICO
Get PDFAbstract ∙ Molecular analyses can contribute to an understanding of the present and past demography of a species. In this study, we analyzed genetic diversity, intraspecific divergence patterns and historical demography of the Orange-fronted Parakeet (Eupsittula canicularis) using molecular data obtained from biological samples collected on the Pacific slope of México from Sinaloa to Guerrero. In addition, we analyzed the possible effect of Quaternary climatic changes on the population of this species. Based on genetic differentiation, and genealogical relationships analysis, we identified three genetic groups with overlapping geographical distributions on the north coast of Michoacán. Apparently, an ancestral group in the Balsas Basin underwent diversification and range expansion, initially towards the north coast of Michoacán and later northward along the Pacific slope to Sinaloa, and southward to the coast of Guerrero. Our results of skyline plot analysis suggest that a population expansion occurred during the Upper Pleistocene. The present analysis contributes to the knowledge of the phylogeographic pattern of E. canicularis in the tropical dry forest of western México, and identifies the Balsas Basin as an important center of diversification for the species.Resumen ∙ Historia demográfica del Periquito Frente-naranja (Eupsittula canicularis) en México Los análisis moleculares pueden contribuir a la comprensión de la demografía actual e histórica de una especie. En este estudio analizamos la diversidad genética, el patrón de divergencia intraespecífica y la demografía histórica del Periquito Frente-naranja (Eupsittula canicularis) utilizando datos moleculares obtenidos de muestras biológicas colectadas en la vertiente del Pacífico desde Sinaloa hasta Guerrero, México. Además, analizamos el posible efecto de los cambios climáticos del Cuaternario sobre la población de esta especie. Con base en el análisis de diferenciación genética y relaciones genealógicas, identificamos tres grupos genéticos que sobrelapan su distribución geográfica en la costa del norte de Michoacán. Aparentemente, un grupo ancestral con distribución en la Cuenca del Balsas sufrió diversificación y expansión de rango hacia la costa norte de Michoacán y por la vertiente del Pacífico hacia el norte hasta Sinaloa, y hacia el sur hasta la costa de Guerrero. Los resultados de los análisis de “skyline plot” sugieren una expansión de la población que ocurrió durante el Pleistoceno superior. El presente análisis contribuye al conocimiento del patrón filogeográfico de E. canicularis en el bosque tropical seco del oeste de México, e identifica a la cuenca del Balsas como un importante centro de diversificación para la especie
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