1,721,048 research outputs found
IMPROVED METHODOLOGY FOR THE COMBINED SPECTROSCOPIC AND CHROMATOGRAPHIC INVESTIGATION OF WATER-SOLUBLE ORGANIC COMPOUNDS IN ATMOSPHERIC AEROSOLS AND FOG
No full textNMR spectroscopic applications to atmospheric organic aerosol analysis – Part 2: A review of existing methodologies and perspectives
Get PDFIn the last decade, the considerable technological progress achieved in parallel science disciplines provides a potential for a breakthrough in NMR atmospheric applications. Improvements in probe sensitivity and in the NMR devices, like innovative tubes with a better filling factor, enable to improve the signal-to-noise ratios of an order of magnitude with respect to the earlier techniques. This already allows for the development of NMR techniques in experimental setups, like laboratory simulation chambers, where the limited sampling volumes and aerosol loads have hampered full application in the past. In parallel, the development of techniques for high-performance data analysis, including metabolomics, and multivariate statistical techniques applied to complex spectral datasets greatly expand the potential of NMR-based aerosol characterization techniques for individual compound identification and source apportionment. To achieve this goal, a more systematic NMR characterization of atmospheric tracers and relevant sources is required
FUNCTIONAL ORGANIC GROUPS APPROACH TO THE CHARACTERIZATION OF BIOMASS BURNING AEROSOL FROM THE AMAZON BASIN
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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
NMR determination of total carbonyls and carboxyls: A tool for tracing the evolution of atmospheric oxidized organic aerosols
No full textNuclear magnetic resonance (NMR) spectroscopy is used to
investigate the chemical composition of organic aerosol in terms
of functional group distribution with a special focus on
secondary organic aerosol (SOA) formation. The knowledge of
the functional group composition is a benchmark for
understanding how SOA components partition into the
particulate phase and undergo chemical transformation. The
paper presents anewchemical derivatization procedure coupled
to protonNMR(1H NMR) analysis for the specific determination
of total carbonylic groups in atmospheric aerosol samples,
which couples with the procedure for determination of total
carboxylic acid groups described in a previous work. A first
deployment of the combined techniques for the analysis of PM10
samples collected in the Po Valley in the warm season
shows that the concentration in the particulate phase of total
carbonyls varies and covaries with respect to those of
carboxylic acids and of less-oxidized functional groups. The
proposed methodology provides thebreakdownof the oxygenated
fraction of the organic aerosol into major functional groups
through well-established chemical methods and can be used
to benchmark the more sensitive and widely used aerosol mass
spectrometric techniques
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
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