1,720,958 research outputs found
Academic emotions, college adjustment, and dropout intention in university students
Get PDFIntroductionIn recent years, due to the COVID-19 pandemic, the entrance and development of university life has become a complex process, making it relevant to investigate which variables could facilitate the adaptation of young people to university. This study aimed to analyze academic emotions and their prediction of university adaptation and intention to drop out.MethodsThe study was quantitative, explanatory, and cross-sectional. A total of 295 university students participated. Academic emotions were assessed with the short version of The Achievement Emotions Questionnaire, adaptation to university life with the reduced version of the Student Adjustment to College Questionnaire, and intention to drop out with three items designed to measure this variable.ResultsDifferences were identified in the emotions experienced during classes and study by students according to the year of entry. We found that males report experiencing emotions such as enjoyment and hope more during evaluations.DiscussionGenerally, students report positive emotions in their academic experience. Positive emotions predict adaptation to university life and the intention to study
Construcción de una Celda de Combustible de Óxido Sólido para la Producción de Electricidad, Mediante el Uso y Optimización de la Perovskita La1-xSrx MnO3 (x = 0.2, 0.4) como Material Constituyente del Electrodo de Oxígeno.
Get PDFTesis presentada para optar al grado de Doctor/a en Energías.La1-xSrxMnO3 (x = 0.2, 0.4) perovskite (LSM) as an oxygen electrode material for solid oxide fuel cells (SOFC) was synthesized by the rapid solution combustion method and its structural,
morphological, mechanical, electrical, and optical characteristics were evaluated by corresponding characterization tools. XRD results showed the coexistence of the rhombohedral
polymorphs R-3c and Pm-3m for the perovskite phase, corroborated by HR-TEM images, showing that the rapid combustion method did not allow the pure formation of the La1-xSrxMnO3 phase (x = 0. 2, 0.4) for calcination temperatures below 1400 and 1500°C respectively, due to the rapid combustion synthesis 500°C for 5 min. The average grain size was observed to increase with calcination time. EDS analysis showed better agreement of stoichiometry with theoretical composition. Apparent porosity decreased with increasing temperature and calcination time due to coalescence of sintering pores. The hardness improved with increasing calcination time and temperature and reached a maximum value of 5.7 GPa which simply coincided with the
bulk density. A similar trend was observed in the resistivity studies as a function of temperature and all samples exhibited a low resistivity of ~1.2 Ω-cm in the temperature range of 600-700°C. For the sample La0.6Sr0.4MnO3 the calculated band gap range from 3.71 to 3.95 eV, showing that the compound may also be a suitable candidate for the development of high frequency
optoelectronic devices. From these, a SOFC with planar design supported on electrolyte was built using the Screen Printing technique, taking as electrolyte the LSGM (La0.8Sr0.2Ga0.8Mg0.2O3) and fuel electrode LSCM (La0.75Sr0.25Cr0.5Mn0.5O3). The cell was evaluated at 600 and 700 °C with 100 ml. min-1 of H2. Curve IV indicated that the OCV increased slightly with increasing temperature, while in closed loop higher power was obtained at higher temperatures. The maximum power achieved was 4.3 mW.cm-2 at 700°C, which corresponded to the lowest range reported in the literature for this type of fuel cell. Possible factors affecting performance are polarization losses due to the thickness of the deposited electrode layers and the existence of micro-cracks in the LSCM fuel electrode.La perovskita La1-xSrxMnO3 (x = 0.2, 0.4) (LSM) como material de electrodo de oxígeno para las celdas de combustible de óxido sólido (SOFC) se sintetizó por el método de combustión rápida en solución y se evaluaron sus características estructurales, morfológicas, mecánicas, eléctricas y ópticas mediante las herramientas de caracterización correspondientes. Los resultados de DRX mostraron la coexistencia de los polimorfos romboédricos R-3c y Pm-3m para la fase perovskita, corroboradas por imágenes HR-TEM, mostrando que el método de combustión rápida no permitió la formación pura de la fase La1-xSrxMnO3 (x = 0.2, 0.4) para las temperaturas de calcinación inferiores a 1400 y 1500°C respectivamente, debido a la rapidez de la síntesis de combustión 500°C durante 5 min. Se observó que el tamaño medio de los granos aumentaba con el tiempo de calcinación. El análisis EDS mostró una mejor concordancia de la estequiometría con la composición teórica. La porosidad aparente disminuyó con el aumento de la temperatura y el tiempo de calcinación debido a la coalescencia de los poros de sinterización. La dureza mejoró con el aumento del tiempo y la temperatura de calcinación y alcanzó un valor máximo de 5.7 GPa que coincidía simplemente con la densidad aparente. Se observó una tendencia similar en los estudios de resistividad en función de la temperatura y todas las muestras presentaron una resistividad baja de ~1.2 Ω-cm en el rango de temperaturas de 600-700°C. Para la muestra La0.6Sr0.4MnO3 la brecha de banda calculados oscilan entre 3.71 y 3.95 eV, lo que demuestra que el compuesto también puede ser un candidato adecuado para el desarrollo de dispositivos optoelectrónicos de alta frecuencia. A partir de estos fue construido una SOFC con diseño planar soportado sobre electrolito mediante la técnica de Screen Printing, tomando como electrolito el LSGM (La0.8Sr0.2Ga0.8Mg0.2O3) y electrodo de combustible LSCM (La0.75Sr0.25Cr0.5Mn0.5O3). La celda fue evaluada a 600 y 700 °C con 100 ml.min-1 de H2. La curva IV indicaba que el OCV aumentaba ligeramente al aumentar la temperatura, mientras que en circuito cerrado se obtenía una mayor potencia a temperaturas más elevadas. La potencia máxima alcanzada fue de 4.3 mW.cm-2 a 700°C, que correspondía al intervalo más bajo señalado en la bibliografía para este tipo de celdas de combustible. Los posibles factores que afectan al rendimiento son las perdidas por polarización debido al grosor de las capas de electrodos depositadas y la existencia de micro fisuras en el electrodo de combustible LSCM.Facultad de IngenieríaDepartamento de Ingeniería de MaterialesConcepció
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
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