1,720,973 research outputs found
Assessment of tropospheric ozone in latin american cities
No full textgraficas, mapas, tablasEn la actualidad, la contaminación atmosférica corresponde al cuarto factor de riesgo en la salud humana en zonas rurales y urbanas después de la hipertensión, fumar y la diabetes. Las ciudades latinoamericanas no están desconectadas con esta problemática y su constante crecimiento demográfico las transformarán en futuros escenarios potencialmente contaminados, si no se realiza una gestión adecuada del recurso aire. El ozono troposférico (O3) es un reconocido contaminante atmosférico que puede afectar negativamente la salud humana, los ecosistemas y el clima. Para evaluar la contaminación por O3 en una región específica, se han desarrollado análisis numéricos de concentración e indicadores en diferentes escalas temporales, con el objetivo de identificar patrones de comportamiento en los datos y correlacionar efectos adversos debido a la presencia de este contaminante en los centros urbanos. Estos análisis permiten mejorar los planes y políticas de gestión de la calidad del aire, potenciando la implementación de estrategias de mitigación y protección de los receptores.
La presente tesis de maestría pretende evaluar la distribución y patrones de las concentraciones e indicadores de O3 a escala regional en Suramérica, a través de la recopilación de información y el análisis de datos de O3 disponibles en 17 estaciones de monitoreo distribuidas en 10 ciudades de 5 países latinoamericanos (Brasil, Chile, Colombia, México, Paraguay), para el periodo comprendido entre el 2000 al 2020. La información relacionada a la concentración e indicadores de O3 fue recolectada de la plataforma de acceso libre del proyecto internacional TOAR (https://join.fz-juelich.de). Los datos fueron evaluados en agrupaciones horarias, diarias y mensuales en función de las condiciones locales como la altitud, el clima, la densidad poblacional, la topografía y los patrones de emisión de precursores; identificando la homogeneidad de las concentraciones y su relación espacio temporal.
Al analizar las series temporales en los datos, se identificó una ausencia generalizada en la homogeneidad de periodos que coincidieran entre los países, indicando la necesidad de reforzar la continuidad del monitoreo de calidad del aire en ciudades latinoamericanas, así como de la publicación de la información en plataformas globales como TOAR. No obstante, se identificó que la metodología propuesta permite hallar correlaciones y diferencias entre las estaciones analizadas.
Los resultados horarios indicaron que la formación de O3 posee una fuerte dependencia de los patrones de emisión de precursores y la relación entre COV/NOX en la atmósfera, siendo el tipo de estación, la cobertura del suelo y la densidad poblacional variables indicativas de esta relación. Este fenómeno se evidenció en los patrones diarios, donde se identificaron incrementos de hasta un 40% en las concentraciones observadas durante los domingos, especialmente en estaciones tráfico, fenómeno relacionado a la acumulación de precursores durante los días laborales.
Para el caso de los patrones mensuales, se evidenció una correlación entre los patrones estacionales meteorológicos y los máximos de concentración registrados. Para países alejados del trópico los mayores registros de O3 se obtuvieron durante la temporada de verano, mientras que para regiones más tropicales o con climas caracterizados por precipitaciones mensuales por encima de los 50 mm, se registraron los máximos de O3 durante el inicio de temporadas de altas precipitaciones, fenómeno relacionado al cambio en el equilibrio químico que implica el lavado atmosférico de precursores.
Por otro lado, dependiendo del indicador o conjunto de indicadores elegidos para evaluar las condiciones de contaminación de una región, se podría generar como producto la selección de diferentes combinaciones de estrategias de control de emisiones y a su vez generar conclusiones diferentes sobre la distribución de los datos de O3 y su nivel de riesgo en los receptores.
Los resultados demuestran la necesidad de definir la población de estudio y conocer los niveles de distribución de los datos promedio de O3. Por ejemplo, para evaluar impactos en la salud humana en ambientes urbanos el uso de indicadores como el MDA8 podrán reflejar el efecto de las concentraciones “altas”, por encima de 75 ppb. Similarmente, indicadores como el SOMO10 reflejarán el cambio en las magnitudes debido a las concentraciones “bajas”, por debajo de 35 ppb. Mientras que, indicadores como el AOT40 que tienen como objetivo evaluar la eficiencia y capacidad productiva de la vegetación o los cultivos, permitirán evaluar el potencial de riesgo asociado a concentraciones medianas – altas, por encima de 40 ppb, en especies vegetales, siendo éste un indicador idóneo de aplicabilidad en estaciones de fondo o localizaciones rurales.
Se destaca que implementar indicadores y generar estándares permite dar seguimiento a las estrategias de control de la contaminación del aire, ya que el no cumplimiento de estos promueve y exige a las autoridades competentes y a la comunidad en general el desarrollo e implementación de acciones directas en las regiones contaminadas para ajustarse a los estándares permitidos.
Finalmente, se realizó un análisis de tendencias y aplicación de modelos de predicción estadística de datos, como las redes neuronales artificiales (ANN). Ambas herramientas permiten identificar cambios en los patrones de comportamiento de los datos, evidenciando por un lado las magnitudes y direcciones de estos, y por otro lado permitiendo estimar valores de O3 no conocidos a partir de variables predictoras para la aplicabilidad en la imputación de bases de datos. Estas herramientas pueden llegar a potenciar la significancia de los resultados por efecto de la continuidad en las series temporales, fomentando la importancia de la generación de protocolos de aseguramiento de datos y la confiabilidad en la información. (Texto tomado de la fuente)Currently, air pollution is the fourth risk factor for human health in rural and urban areas after hypertension, smoking, and sugar blood. Latin American cities are not disconnected whit this problem and their constant demographic growth will transform them into potentially polluted scenarios if adequate management of the air resource is not carried out. Tropospheric ozone (O3) is an air pollutant that can adversely affect human health, ecosystems, and climate. To assess O3 pollution in a specific region, numerical concentration analyses and O3 metrics have been developed at different time scales, to identify patterns in the data and correlate adverse effects due to the presence of this pollutant in the urban areas. These analyzes could improve air quality management plans and policies, enhancing the implementation of mitigation and protection strategies for receptors.
This master's thesis aims to evaluate the O3 concentrations and metrics, their distribution, and patterns in a regional scale in South America. O3 data were obtained from 17 monitoring stations distributed in 10 cities in 5 Latin American countries (Brazil, Chile, Colombia, Mexico, Paraguay), for the period from 2000 to 2020. Information was collected from the free access platform of the international TOAR project (https://join.fz-juelich.de). The data were evaluated in hourly, daily, and monthly bases according to local conditions such as altitude, climate, population density, topography, and precursor emission patterns, identifying the homogeneity of concentrations and their space-time relationship.
Time-series analyses showed a general absence in the homogeneity of periods that coincided between the countries, indicating the need to strengthen the continuity of air quality monitoring in Latin American cities. As well as the need for publication of information on global platforms such as TOAR. However, the proposed methodology allowed to found correlations and differences between the stations analyzed.
Hourly patterns indicated that O3 formation had a strong dependence on emission precursor patterns and the VOC/NOX ratio in the atmosphere, being the type of station, land cover, and population density indicative variables of this relationship. This phenomenon was observed in daily patterns, where concentrations increased up to 40% on Sundays, especially in traffic stations, a phenomenon related to the accumulation of precursors during working days.
For monthly patterns, a correlation was evidenced between seasonal weather patterns and maximum recorded concentrations. For countries far from the tropics, the highest O3 records were obtained during the summer season, while for tropical regions or climates characterized by monthly rainfall above 50 mm, the O3 peaks were recorded during the beginning of high-rainfall seasons, perhaps induced by a change in atmospheric chemical balance due to scavenging.
On other hand, depending on the indicators set chosen to assess the pollution conditions, different combinations of emission control strategies could be selected and different conclusions about the O3 distribution and their level of risk in the receptors could be generated.
The results suggest the need to define the study population and characterized the distribution of the O3 levels. For example, to assess impacts on human health in urban environments, the use of indicators such as MDA8 will reflect the effect of "high" concentrations, above 75 ppb. Similarly, indicators such as SOMO10 will reflect the change in magnitudes due to "low" concentrations, below 35 ppb. While indicators such as AOT40, which aim to evaluate the efficiency and productive capacity of vegetation or crops, will allow assessing the potential risk related to medium-high concentrations, above 40 ppb, being an adequate indicator for applicability in background stations or rural areas.
Hence, the use of indicators and the establishment of indicator standards allow for monitoring the control strategies of air pollution. Since non-compliance with these standards promotes and requires the competent authorities and the community to develop and to implement actions in the polluted regions.
Finally, trend analysis and statistical prediction models were applied, using artificial neural networks (ANN). The exercise allows to evaluate patterns and changes in data, evidencing the data magnitude and direction, and allowing to estimate unknown O3 values from predictor variables, for the applicability in data filling. Tools cloud be combined to enhance the significance of the results because of the continuity in the time series. Results that can promote the importance of the generation of data assurance protocols to enhance the reliability of the information.MaestríaMagíster en Ingeniería - Ingeniería QuímicaContaminación atmosférica y calidad del aireQuímica Y Procesos.Sede Manizale
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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