1,761,263 research outputs found
Haloethane Reactions over the Chromia Cr₂O₃ (1012) Surface
No full textEthyl iodide and ethyl chloride have been used as reactants to produce ethyl fragments on the stoichiometric α-Cr₂O₃ (1012) surface by means of thermal dissociation. Ethyl iodide is dissociated giving iodine adatoms and ethyl fragments bound to surface Cr cation sites, while ethyl chloride is dissociated giving chlorine adatoms and ethyl fragments. No oxygenated products are observed in thermal desorption, suggesting the 3-coordinate lattice oxygen on the stoichiometric α-Cr₂O₃ (1012) surface is very stable, and no nucleophilic attack occurs at the carbon atoms on surface ethyl fragments.
For both reactants, the only reaction products observed are ethylene gas (CH₂=CH₂), ethane gas (CH₃-CH₃), hydrogen gas (H₂) and halogen adatoms (Clads or Iads). In thermal desorption experiments, all the gas phase products from ethyl chloride are produced in a reaction-limited, high temperature desorption feature attributed to a rate limiting β-hydride elimination from surface ethyl fragments. Similar product desorption features are observed for the reaction of ethyl iodide. However, the reaction of ethyl iodide also produces ethylene and ethane via a low temperature, desorption-limited reaction channel. It is postulated that I adatoms produced in the reaction of ethyl iodide thermal desorption might somehow promote a low temperature route to products that Cl adatoms do not.Master of Scienc
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
. 1012 Año 21 (2022) enero. El Tlacuache
No full textEl tema de la domesticación de especies en los últimos años se ha puesto en relieve, ya que permite comprender la diversidad de interacciones culturales de las poblaciones humanas con el medio natural. Estas perspectivas se han adquirido gracias al desarrollo de nuevas técnicas para analizar restos orgánicos, las que permitieron responder algunas preguntas que habían quedado en el aire desde la formulación de la teoría evolutiva con Darwin, pero también generó nuevas preguntas alrededor de ello, por ejemplo: ¿el proceso de domesticación fue igual en todos los continentes? ¿Cuáles son los impactos de la domesticación en los paisajes naturales?- La domesticación de organismos, nuevas perspectivas del tema por Eduardo Corona Martínez. - La escultura de Xochicalco. La fauna por Claudi Itzel Alvarado León.Escultura de Jabali de Göbekli Tepe, Urfa Museum Autor: Dosseman (https://shorturl.at/hirzH). Göbekli Tepe, Şanlıurfa. Autor: Teomancimit (https://shorturl.at/lABLN)Alvarado L., C. y E. Corona-M. 2019. Consideraciones sobre los felinos en el sitio arqueológico de Xochicalco, Morelos, México. Archaeobios 14 (1):92-106. ⏤ 2020. La escultura singular de un pez en un sitio del Epiclásico mesoamericano. (Xochicalco, Morelos, México). Archaeobios 13 (1):23-40.Corona-M., E. 2014. “Relieves Con Motivos Zoomorfos en Xochicalco, Morelos.” Archaeobios 8 (1): 17–25.Corona-M. E., A. Casas Fernández, A. Argueta Villamar, C.I. Alvarado León. 2021. La domesticación de especies y paisajes, pp: 78-98 en Prieto Hernández, D. y Castilleja González, A. (Coords). México: grandeza y diversidad. INAH, FCE, IEPSA SA de CV y CONALITEG, México. https://www.mediateca.inah.gob.mx/islandora_74/islandora/object/libro%3A843Dietrich L, Meister J, Dietrich O, Notroff J, Kiep J, Heeb J, et al. (2019) Cereal processing at Early Neolithic Go¨bekli Tepe, southeastern Turkey. PLoS ONE 14(5): e0215214. https://doi.org/10.1371/journal.pone.021521
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
Author Recognition Image 13
No full textThis image was taken at the Author Recognition Reception March 20, 2012.https://scholarworks.gvsu.edu/author_images/1012/thumbnail.jp
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