1,720,974 research outputs found
Method Development for Comprehensive Two-Dimensional Liquid Chromatography Separations
Get PDFMethod development continues to be a significant barrier to wider adoption of comprehensive two-dimensional liquid chromatography (LC×LC). Several groups have discussed different frameworks for systematically approaching method development over the past 15 years or so. In this chapter we propose a generic approach to developing LC×LC methods that leverages these past experiences and knowledge. The specific route one takes through this workflow will depend on which method performance metrics are most important for the application at hand. Then, we use two case studies of the development of real LC×LC methods to illustrate how the method development approach can be used in practice. Finally, we discuss strategies that can be used to optimize LC×LC methods, including recent progress toward automating this work. Method development for LC×LC is a highly active research area where we expect great strides to be made in the near future
Selecting Separation Modes and Selectivities for Multi-Dimensional LC
Get PDFOne of the most important steps in the development of any 2D-LC method involves choosing which modes of separation to use (e.g., reversed-phase (RP), ion-exchange, etc.). The rationale leading to this step involves not only the characteristics of the analytes in the sample at hand, but also the likelihood that the two separations chosen at this stage will work well together in a 2D separation system. In this chapter we first discuss how the concept of “sample dimensionality” can be used as a framework for choosing which two separation modes to use. We then go on to discuss how different combinations of modes do or do not work well together in 2D systems, and briefly discuss strengths and weaknesses of individual separation modes as they relate to multi-dimensional separations. Finally, in the specific case of RP separations we summarize strategies that have been used to select specific stationary phases for use in 2D-LC separations involving RP in at least one dimension. This alone can be a challenge given the commercial availability of more than 1,000 different phases
Data Analysis for Multi-Dimensional Liquid Chromatography
Get PDFMulti-dimensional liquid chromatography methods, particularly those involving comprehensive multi-dimensional separation, often produce datasets that are much richer and more complex than those normally obtained by conventional one-dimensional separations. Of course, it is great for the analyst to be able to draw on these richer datasets, but the volume and complexity of the data pose new data analysis challenges that cannot be addressed using tools developed for one-dimensional chromatography alone. In this chapter we first discuss recent advances in the development of methods for treating one-dimensional chromatography data, as these do indeed form the basis of methods for treating two-dimensional data. We then go on to discuss challenges unique to the analysis of data from multi-dimensional chromatography methods, and the methods that have been developed to address these challenges. Finally, we discuss multi-way analysis methods that not only are capable of dealing with multi-dimensional data, but are also well suited to capitalize on the power of these methods for resolving chromatographic signals from background signals, and from each other (i.e., mathematical resolution of overlapping peaks). Future advances in this area will benefit from the use of benchmark datasets that allow comparison of new data analysis methods to established ones, and evaluation of method performance using real data from multiple sources
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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