1,720,984 research outputs found
The topological and geometric analysis of organic crystal systems
No full textThe aim of this study was to use topological descriptors to gain insight into the crystal packing of organic compounds and generate crystal structure landscapes that are representative of the packing motif that might be identified by a crystallographer. These descriptors are applied to both sets of experimental compounds, as might be found in the Cambridge Structural Database, for example, or to the large sets of compounds that might be generated as the output of crystal structure prediction calculations.The crystal structures of fluorinated benzylideneanilines, polyaromatic hydrocarbons, azapentacenes and the nictotinamide:benzoic acid co-crystal were studied through the lens of a novel topological descriptor. This descriptor is constructed from the persistent homology of a set of molecular centroids and orientation vectors extracted from the crystal structure, the homology being computed on a six dimensional space. We were able to generate crystal structure landscapes that completely separated all known packing classes of fluorinated benzylideneaniline as identified by a subject matter expert. We were also able to completely separate the structures of two classes of nictotinamide:benzoic acid co-crystals that were identified to belong to two funnels on the potential energy landscape corresponding to its known polymorphs. While the azapentacens and polyaromatic hydrocarbons proved more resistant to a full description with persistent homology, we were able to produce landscapes that preserve some trends which are consistent with their canonical packing motifs. We also showcase how crystal structure landscapes can be constructed using supervised dimensionality reduction in the context of some existing high fidelity data with known packing motifs in order to obtain landscape that extenuate these chemically relevant features
Dataset in support of the thesis 'The topological and geometric analysis of organic crystal systems: Supplementary information
No full textData pertaining to the PhD thesis "The Topological and Geometric Analysis of Organic Crystal Systems" by Jack Doyle. All raw crystal structure data, supplementary python scripts and figures used in the compilation of the thesis can be found here.
</span
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
Resurrecting second harmonic generation (SHG) case study
Full text linkThe preservation, accessibility, and reuse of scientific data are increasingly vital in contemporary research. Historical datasets, often termed legacy data, provide significant opportunities for new discoveries, validation of past results, and insights through modern analytical methods. Despite their potential value, legacy datasets frequently suffer from poor documentation, outdated formats, and technological obsolescence, complicating their reuse. This report addresses these challenges through the reconstruction of databases originating from Second Harmonic Generation (SHG) experiments, conducted as part of a doctoral research project completed in 2011 at the University of Southampton
Resurrecting Second Harmonic Generation (SHG) Case Study Dataset
No full textThis dataset record provides the database scripts and tableau code that accompanies the Resurrecting Second Harmonic Generation (SHG) Case Study.
Please note Please note that due to the size of the database scripts, these are stored on the University of Southampton file servers and can be requested via this form: https://library.soton.ac.uk/datarequest</span
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
- …
