1,720,956 research outputs found
Caracterización estructural y evolutiva del complejo FTSW/FTSI de Escherichia Coli
No full textLa división bacteriana es un proceso esencial que ocurre gracias a un conjunto de proteínas que forman el divisoma. Las proteínas de membrana FtsW y Ftsl son parte de esta maquinaria de división, que actúan como un complejo en la fase tardía, luego de la segregación del cromosoma y de la incorporación molecular se tiene y su función especifica permanece bajo un halo de duda
Termodinámica de la unión de Ca2+ a hemicanales de hCx2
No full textMemoria (Ingeniero en Biotecnología)Los canales de unión en hendidura (GJC por sus siglas en inglés: Gap Junction Channel) son
canales presentes en eucariontes, formados por dos hemicanales (HCs) o conexones que
conectan los citoplasmas de dos células adyacentes. Cada HC se compone de seis proteínas
llamadas conexinas (Cx) y pueden estar desacoplados, conectando el citoplasma con el
espacio extracelular. Los HC que no forman GJC participan de varios procesos fisiológicos y
suelen estar cerrados en condiciones fisiológicas, aunque su apertura puede ser gatillada por
cambios en las concentraciones extracelulares de Ca
2+
. No obstante, luego de años de
estudios, aún no hay consenso en la comunidad dedicada al tema, sobre el mecanismo
mediante el cual los iones calcio regulan la apertura y cierre de los HC, particularmente de HC
formados por Cx26, una de las conexinas más estudiadas. La aplicación de protocolos de
simulación molecular como complemento a los estudios experimentales han ayudado a estudiar
las relaciones estructura-función de estos canales. En este trabajo se realizaron protocolos de
modelamiento comparativo de proteínas y simulación molecular para generar las diversas
combinaciones posibles de HC-Cx26 unida a calcio, considerando sus 6 monómeros. Con los
diferentes modelos planteados y aplicación de la técnica conocida como transformación
alquímica, se estudió el efecto termodinámico asociado a la unión de iones calcio. Los
resultados indican que no hay una preferencia termodinámica entre las diferentes
configuraciones de las mismas cantidades de ion calcio en el sistema, además, indican que el
proceso de unión de iones Ca
2+ no presenta propiedades cooperativas en cuanto a la
termodinámica asociada y que el sacar iones calcio del sistema es desfavorable
energéticamente.Gap Junction Channels (GJC) are channels found in eukaryotes, formed by two hemichannels
(HCs) or connexons that connect the cytoplasms of two adjacent cells. Each HC is composed of
six proteins called connexins (Cx) and may be uncoupled, connecting the cytoplasm with the
extracellular space. HCs that do not form GJC participate in various physiological processes and
are typically closed under physiological conditions, although their opening can be triggered by
changes in extracellular Ca2+ concentrations. However, after years of studies, there is still no
consensus in the community dedicated to the subject regarding the mechanism by which
calcium ions regulate the opening and closing of HCs, particularly HCs formed by Cx26, one of
the most studied connexins. The application of molecular simulation protocols as a complement
to experimental studies has helped explore the structure-function relationships of these
channels. In this investigation, comparative protein modeling protocols and molecular simulation
were conducted to generate various possible combinations of Ca2+-bound Cx26 HC,
considering its 6 monomers. With different models and the application of the alchemical
transformation technique, the thermodynamic effect associated with the binding of calcium ions
was studied. The results indicate that there is no thermodynamic preference among different
configurations with the same amounts of calcium ion in the system. Additionally, they suggest
that the Ca2+ binding process does not exhibit cooperative properties in terms of associated
thermodynamics and the unbinding of calcium ions is unfavorable energetically
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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