1,720,954 research outputs found
Modelo de liberación del VIH-1 de la membrana plasmática, autoensamblaje de su red y de cápsides icosaédricas
No full textEl VIH es un virus que, hasta la fecha, sigue infectando a miles de personas alrededor del mundo. Actualmente una persona infectada no tiene como único término la muerte, como era hasta hace algunas décadas, sino que puede llevar una vida normal con tratamientos de antiretrovirales. Esto se ha logrado gracias al amplio estudio de este virus. Sin embargo, aunque se conozca en términos generales como se lleva acabo su ciclo de replicación, los detalles de este proceso siguen siendo desconocidos. En este trabajo, a partir de simulaciones computacionales de dinámica molecular, con modelos moleculares bastante sencillos, se indaga en el proceso de autoensamblaje del VIH. En primer lugar, se replicó la formación de una partícula vírica a partir de sus unidades estructurales. Esto incluye el ensamblaje de los bloques constructores del virus sobre un modelo de membrana lipídica, su envolvimiento con ella y su separación de la membrana. Justo como el VIH y otros virus proceden para replicarse. En segundo lugar, se ensambló la red hexagonal que forma el VIH, a partir de sus unidades proteicas, en su proceso de multimerización sobre la parte interna de la membrana lipídica de la célula infectada. Esta red fue ensamblada sin la presencia de elementos como la membrana lipídica, entre otros, que sirven como andamiajes y que intervienen en este proceso del virus. Para este fin se usó un modelo molecular que se basa en la proteína Gag que sirve como bloque constructor (unidad proteica) del virus del VIH. Las principales interacciones atractivas de la proteína Gag son modeladas de dos maneras: con potenciales de pozo cuadrado y con potenciales de Lennard-Jonnes. En ambos casos se obtuvieron buenos resultados. Finalmente, variando ligeramente el modelo molecular para ensamblar la red, se autoensamblaron las cápsides icosaédricas T=1, T=3 y T=4, las cuales son estructuras de forma esférica que los virus usan para resguardar su material genético. Esto se logró tan solo con variar un parámetro angular ϕ de la molécula y sin la necesidad de modificar las reglas de interacción entre las mismas
Autoensamblaje de tribloques coloidales
Full text linkEl alto manejo alcanzado en la creación de tribloques coloidales abre la posibilidad de formar nuevas redes abiertas por medio del autoensamblaje de estos tribloques. En este trabajo se buscó el autoensamblaje de redes abiertas, propuestas a partir de la creación de nuevos tribloques coloidales, mediante la simulación de partículas con parches atractivos vibrantes en dos dimensiones. Se obtuvieron tres redes abiertas con sus respectivos diagramas de fase. Una de las redes se forma con un tribloque con dos parches atractivos de igual tamaño formando un ángulo de ciento cincuenta grados entre ambos con el centro del tribloque. Las dos redes restantes se lograron formar usando una molécula, integrada por cinco y seis partículas, como bloque constructor. A la par de la creación de las redes abiertas, se aprendieron las reglas del autoensamblaje para crear este tipo de redes. Con el conocimiento adquirido se da un paso adelante en el objetivo de auto ensamblar todo tipo de estructuras en tres dimensiones con las geometrías deseadas, con el fin de usarlas a nuestra conveniencia
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
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