1,720,978 research outputs found
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
Middle-Late Pleistocene Eastern Mediterranean nutricline depth and coccolith preservation linked to Monsoon activity and Atlantic Meridional Overturning Circulation
Full text linkThe eastern Mediterranean Sea lies under the influence of high- and low-latitude climatic systems. The northern part of the basin is affected by Atlantic depressions and continental and polar air masses that promote intermediate and deep-water formation. The southern part is influenced by subtropical conditions and monsoon activity. Monsoon intensification results in enhanced freshwater discharge from the Nile River and other (now dry) systems along the North African margin. This freshwater influx into the Mediterranean Sea reduces surface water buoyancy loss. Disentangling the influences of these diverse climatic forcings is hindered by inherent proxy data limitations and by interactions between the climatic forcings. Here we use a wealth of published and new paleoclimate records across Termination II to understand the impacts of the higher latitude and subtropical/monsoon climate influences on coccolithophore ecology and holococcolith preservation in Aegean Sea sediment core LC21. We then use these findings to interpret coccolith assemblage variations at Ocean Drilling Program Site 967 (located nearby LC21, at the Eratosthenes Seamount) during multiple glacial-interglacial cycles across the Middle Pleistocene (marine isotopic stages 14–9). The LC21 analysis suggests that holococcolith preservation was enhanced during Heinrich Stadial 11 (∼133 ka) and cold spell C26 (∼119 ka). These two events have been previously linked to cold conditions in the North Atlantic and Atlantic Meridional Overturning Circulation weakening. We propose that associated atmospheric perturbations over the Mediterranean Sea promoted deep-water formation, and thus holococcolith preservation. Similarly, in the Middle Pleistocene (MIS 14-9) of Site 967, we observe temporal coincidence between ten episodes of enhanced holococcolith preservation and episodes of Atlantic Meridional Overturning Circulation slowdown. In Site 967, we also identified repeated fluctuations in placoliths and in Florisphaera profunda, which indicate nutricline depth variations. The development of a deep chlorophyll maximum is associated with the North Africa and wet phases, as recently observed using elemental proxy records at Site 967, during the deposition of sapropel layers. A further deep chlorophyll maximum development is identified during MISs 12 and 10, as a result of pycnocline and nutricline shoaling within the lower part of the photic zone due to glacial sea-level lowering and water mass transport reduction at both the Gibraltar and Sicily Straits. Finally, enhanced holococcolith preservation during cold/dry events is clearly correlated to weakened monsoon activity in both Africa and Asia.</p
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
Coccolithophore calcification, life-cycle dynamics and diversity response to a warming and acidifying Mediterranean Sea
Full text linkBibliografia.RESUMEN Esta tesis se llevó a cabo bajo el proyecto "Acidificación oceánica del Mediterráneo europeo en un clima cambiante (MedSeA, por sus siglas en inglés)", financiado por la Comisión Europea en el marco del Programa 7 (http://medsea-project.eu, número 265103). El proyecto MedSeA estimuló la investigación sobre el efecto combinado del calentamiento de los océanos y la acidificación en la biogeoquímica y los ecosistemas mediterráneos. La presente tesis se centra en los coccolitóforos, un grupo de fitoplancton calcificante fuertemente conectado al clima global a través del ciclo del carbono. Ambos estadios de vida calcificados (heterococolitóforos y holococolitóforos) de estas algas unicelulares se encuentran comúnmente en el Mar Mediterráneo. Aquí, la comunidad en general presenta un alto grado de diversidad de especies, aparentemente más alto que en el Mar Rojo adyacente y el Océano Atlántico. Por otra parte, el Mar Mediterráneo es un área sometida a fuertes oscilaciones estacionales ambientales y presiones antropogénicas. El Mar Mediterráneo està considerado un "punto caliente" para el cambio climático, estando entre las regiones oceánicas bajo un calentamiento y acidificación más rápidos. Se espera que estos procesos provoquen no sólo un aumento de las temperaturas y cambios en el sistema del carbonato, sino también intensificar la estratificación de la columna de agua. Se prevé que tales cambios ambientales influirán en las poblaciones de cocolitóforos, de formas que aún no se entienden. Esta tesis contribuye a la comprensión de las respuestas de los cocolitóforos a un Mar Mediterráneo cambiante basada en i) muestras de agua recogidas a lo largo de un transecto O-E durante el "MedSeA Ocean Research Cruise" (crucero de investigación oceánica de MedSeA) (https://medseaocancruise.wordpress.com), que capturó su población regional y diversidad (Capítulos II, III, IV); y ii) muestras de agua colectadas durante el experimento de mesocosmos "MedSeA Crete" (https://medseacrete2013.wordpress.com), que probó los efectos combinados del calentamiento oceánico y de la acidificación en el ecosistema pelágico oligotrófico del Mediterráneo Oriental bajo limitación de nutrientes (Capítulo V). Estos dos conjuntos de observaciones permitieron el examen de varios aspectos de la población de cocolitóforos, tales como: i) la masa media del cocolito de Emiliania huxleyi, su distribución y los principales controles morfológicos / ambientales (Capítulo II); ii) las abundancias absolutas de heterococolitóforo y holococolitóforo, sus distribuciones relativas, patrones de diversidad y hipotéticos desencadenantes de las transformaciones de la fase de vida (Capítulo III y IV); y iii) la variabilidad en la abundancia absoluta de la población total de cocolitóforos, heterococolitóforos y holococolitóforos totales, y de las especies predominantes (E. huxleyi, Rhabdosphaera spp.) en la comunidad de cocolitóforos bajo calentamiento y acidificación en un entorno oligotrófico (Capítulo V). En general, los resultados presentados en esta tesis sugieren que los cocolitóforos que habitan el Mar Mediterráneo serán influenciados de diversas maneras por las perturbaciones ambientales proyectadas: la masa promedio del cocolito de E. huxleyi cambiará, siguiendo cambios futuros en la proporción de las variedades de calcificación y probablemente causando cambios en la producción y exportación de carbonato en el Mar Mediterráneo; la fase haploide podría ser favorecida sobre la fase diploide en muchas especies de cocolitóforos, aumentando en última instancia la proporción de los holo- sobre los hetero-cocolitóforos y la diversidad de los holococolitóforos; en el Mediterráneo Oriental, el calentamiento y la limitación de nutrientes, antes que la acidificación, tienden a reducir la población total de cocolitóforos, aunque los crecimientos óptimos específicos de las especies y cepas pueden modular esta respuesta.SUMMARY This thesis was conducted under the "European Mediterranean Sea Acidification in a changing climate" (MedSeA) project, funded by the European Commission under Framework Program 7 (http://medsea-project.eu; grant number 265103). The MedSeA project stimulated research on the combined effect of ocean warming and acidification on Mediterranean biogeochemistry and ecosystems. The present thesis focuses on coccolithophores, a group of calcifying phytoplankton tightly connected to the global climate through the carbon cycle. Both calcified life stages (heterococcolithophores and holococcolithophores) of these unicellular algae are commonly found in the Mediterranean Sea. Here, the overall community presents a high degree of species diversity, apparently higher than in the adjacent Red Sea and Atlantic Ocean. On the other hand, the Mediterranean Sea is an area subject to strong environmental seasonal oscillations and anthropogenic pressures. The Mediterranean Sea is considered a "hot spot" for climate change, being among the oceanic regions under faster warming and acidification. These processes are expected to cause not only a rise in temperatures and shifts in the carbonate system, but also to enhance water column stratification. It is anticipated that such environmental changes will influence the coccolithophore populations, in ways that are not yet understood. This thesis contributes to the understanding of coccolithophore responses to a changing Mediterranean Sea based on i) water samples collected along a W-E transect during the MedSeA Ocean Research Cruise (https://medseaoceancruise.wordpress.com), which captured their regional population and diversity (Chapters II, III, IV); and ii) water samples collected during the MedSeA Crete mesocosm experiment (https://medseacrete2013.wordpress.com), which tested the combined effects of ocean warming and acidification on the oligotrophic Eastern Mediterranean pelagic ecosystem under nutrient limitation (Chapter V). These two sets of observations allowed the examination of several aspects of the coccolithophore population such as i) the average coccolith mass of Emiliania huxleyi, its distribution and the main morphological / environmental controls (Chapter II); ii) the heterococcolithophore and holococcolithophore absolute abundances, their relative distributions, diversity patterns, and hypothetical triggers of life phase transformations (Chapter III and IV); and iii) the variability in absolute abundance of the total coccolithophore population, total heterococcolithophores and holococcolithophores, and of the predominant species (E. huxleyi, Rhabdosphaera spp.) in the coccolithophore community under warming and acidification in an oligotrophic setting (Chapter V). Overall, the results presented in this thesis suggest that coccolithophores inhabiting the Mediterranean Sea will be influenced in various ways by projected environmental perturbations: E. huxleyi average coccolith mass will change, following future shifts in the proportion of calcification varieties and likely cause changes in the carbonate export production in the Mediterranean Sea; the haploid phase could be favoured over the diploid phase in many coccolithophore species, ultimately increasing the proportion of holo- over hetero-coccolithophores and holococcolithophore diversity; in the Eastern Mediterranean Sea, warming and nutrient limitation, rather than acidification, tend to reduce the total coccolithophore population, although species specific and strain specific growth optima may modulate this response
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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