1,720,964 research outputs found
A new approach to detect and study ion channel formation in microBLMs
No full textIn this paper, an innovative and versatile approach to detect pore formation in microBLMs and to investigate their ion selectivity is described. For the first time, both electrochemical impedance spectroscopy and conductivity measurements are performed on the same membrane, providing a simple, long-lasting and cheap method which can find applications in various ion channel-involving research fields. We make use of this improved experimental procedure to obtain for the first time a range of values to characterize homogeneous polycarbonate-supported microBLMs. To test the validity of our method, the well-known. channel-forming peptide gramicidin D was first employed. Then, we applied our approach to the study of the still unclear membrane interaction mechanisms of the peptides trichogin GA IV and phospholamban, finding that both can form ion channels in biomimetic models. The phospholamban-generated ion channels could be a promising therapeutic target in heart failures and other cardiac diseases. Our methodology might also be useful for detecting new drugs with ion-channel blocking action. (C) 2011 Elsevier B.V. All rights reserved
A Peptide-tethered Lipid Bilayer on Mercury as a Biomimetic System
No full textA novel spacer consisting of a hexapeptide molecule with a high tendency to form a 310-helical structure, which terminates with a sulfydryl group for anchoring to a metal, was tailored for use as a tethered hydrophilic spacer to be interposed between a metal support and a lipid bilayer. The thiol peptide has two triethylenoxy side chains that impart it a satisfactory hydrophilicity and are intended to keep the anchored thiol peptide chains sufficiently apart so as to accommodate water molecules and inorganic ions and to create a suitable environment for the incorporation of integral proteins. This thiol peptide was anchored to a hanging mercury drop electrode. The formation of a phospholipid bilayer on top of the self-assembled thiol peptide was carried out by a novel procedure which exploits the spontaneous tendency of a lipid film to form a bilayer when interposed between two hydrophilic phases. The resulting mercury-supported thiol peptide/lipid bilayer system was characterized by ac voltammetry with phase resolution, chronocoulometry, and impedance spectroscopy. The suitability of this tethered film as a biomembrane model was tested by incorporating ubiquinone-10 and valinomycin
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
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