1,720,954 research outputs found
CRECIMIENTO Y CARACTERIZACIÓN DE NANOESTRUCTURAS DE INxGA1-xN DEPOSITADAS POR CVD Y MOCVD SOBRE SUBSTRATOS DE SI Y AU/SIO2
No full textEl crecimiento de los nitruros del grupo III (InN-GaN-AlN) es un factor importante en el
desarrollo de dispositivos optoelectrónicos. La investigación sobre el efecto de los
substratos en los depósitos de nanoestructuras y microestructuras de estos nitruros se ha
convertido en un tema de investigación actual. En este proyecto de investigación se reporta
el efecto de los substratos de silicio y dióxido de silicio cubierto con una capa de oro sobre
el crecimiento del nitruro de galio-indio usando los métodos de depósito por vapor químico
y de depósito por vapor químico organometálico. Las propiedades de estructura cristalina,
superficie y emisión del InGaN son estudiadas utilizando las técnicas de caracterización de
difracción de rayos X, microscopia electrónica, termoluminiscencia y catodoluminiscencia
Effect of the indium concentration on the optical properties of InxGa1-xNfilms in hexagonal phase
No full textLa aplicación de los nitruros del grupo III (InN-GaN-AIN) en dispositivos optoelectrónicos ha generado importantes avances en el desarrollo de emisores de luz, en el rango de longitudes de onda desde el UV hasta el visible. En particular, el InxGa1-xN es una cerámica novedosa debido a su amplio ancho de banda de la energía prohibida (0.7 eV a 3.4 eV), la cual es posible variar con la concentración de indio en la solución sólida. En este trabajo, se reporte el efecto de la concentración de indio sobre las propiedades ópticas de una serie de películas de InxGa1-xN (0≤x0.3) en fase hexagonal, depositadas sobre zafiro utilizando la técnica de depósito por vapor químico. En específico, los resultados de la caracterización óptica realizada por medio de las técnicas de espectroscopia de absorción UV-visible y fotoluminiscencia. Además, se presentan los resultados de las técnicas electrónicas de microscopia electrónica de barrido y difracción de rayos X. Se reporta la emisión extrínseca en la región de longitudes de onda de ≈570 nanómetros dominante en todas las películas de InxGa1-xN y la presencia de las fases indeseables derivadas de indio (In203,InN y clusters In metálico). Finalmente, se presenta la correlación de la energía de la banda prohibida y la concentración de indio incorporada en las películas de InxGa1-xN obtenida por los métodos de absorción, fotoluminiscencia y difracción de rayos X.The application of the nitrides of group III (InN-GaN-AIN) in optoelectronic devices has important advances in the development of light emitters in the wavelength region from UV to visible. In particular, the InxGa1-xN is a novel ceramics due to its wide band gap (0.7 eV to 3.4 eV), which is possible to vary with the indium concentration in the solid solution. In this work, the effect of indium concentration on the optical propierties of a series of InxGa1-xN films (0≤x≤0.3) in hexagonal phase deposited on sapphire using the technique of chemical vapor deposition CVD) is reported. The results of optical characterization of absortion spectroscopy and photoluminescence (PL) are reported. In addition, the electronic techniques results of scanning electron microscope (SEM) and X-ray diffraction (XRD) are presented. An extrinsic emission in the wavelenght region of ≈ 570 nm dominant in all the InxGa1-xN films and the presence of undesirable phases derived from indium (In203 InN and metallic In clusters) are reported. The correlation of the band gap energy and the indium concentration obtained by absortion, photoluminescence and X-ray diffraction techniques is presented
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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