1,720,989 research outputs found
Model studies on the function of acidic matrix proteins in biomineralization
Full text linkFricke M. Modellstudien zur Funktion saurer Matrixproteine in der Biomineralisation. Bielefeld (Germany): Bielefeld University; 2004.In this work model studies on the oriented growth of CaCO3 at biomimetic interfaces were performed. The primary structure of acidic proteins which control the texture of biogenic CaCO3 were mimicked with oligoacids based on calixarenes, resorcarenes and peptides. Crystallization studies underneath Langmuir monolayers have shown that macrocyclic oligoacids act as templates for CaCO3 crystal growth. Systematic structural variations of various organic matrices and investigations on the influence of these on the growth of CaCO3 have shown that the average charge density of the organic template is the dominant factor which fixes the selection of the CaCO3 polymorphs and the growth direction of the inorganic constituents. Crystallization of CaCO3 in the presence of acidic oligopeptides yield truncated calcite rhombohedra with specifically inhibited crystal faces which has been reported before exclusively for natural acidic proteins. Since conformationally flexible peptides stabilize two energetically different crystal faces, the results point to the influence of electrostatic effects. Therefore, an epitaxial correlation is ruled out for all presented examples.Im Mittelpunkt der Arbeit stehen Modellstudien zum gerichteten Wachstum von CaCO3 an biomimetisch strukturierten Grenzflächen. Die Primärstruktur saurer Proteine, die die Textur biogener Kristallphasen von CaCO3 steuern, wurde mit Oligosäuren auf Basis von Calixarenen, Resorcarenen und Peptiden imitiert. Die Ergebnisse der Kristallisationsstudien unter Langmuir-Monoschichten haben gezeigt, dass die makrozyklischen Oligosäuren eine Templatwirkung auf das Wachstum von CaCO3 ausüben. Über das Moleküldesign wurden die molekularen Eigenschaften so angepasst, dass der Einfluss der Molekülgröße, der Koordinationsgeometrie und der Ladungsträgerdichte auf die Templat-induzierte Kristallisation von CaCO3 bestimmt werden konnte. Die mittlere Ladungsträgerdichte in der Monoschicht kontrolliert sowohl das orientierte Kristallwachstum von CaCO3 als auch die Polymorphselektion. In Gegenwart saurer Oligopeptide führte die Kristallisation von CaCO3 zu trunkierten Calcitrhomboedern mit spezifisch inhibierten Kristallflächen, die zuvor ausschließlich von natürlichen Proteinen induziert wurden. Da zwei energetisch unterschiedliche Kristallflächen von konformativ flexiblen Peptiden stabilisiert wurden, deuten die Ergebnisse erneut auf den Einfluss ungerichteter elektrostatischer Effekte hin. Eine epitaktische Beziehung wurde daher für alle vorgestellten Beispiele ausgeschlossen
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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