1,720,964 research outputs found
Natürliche und anthropogene organische Spurenstoffe in küstennahen Meeressedimenten: Gehalte und Verteilung von polyaromatischen Kohlenwasserstoffen
Get PDFPolycyclic aromatic hydrocarbons (PAHs) are a class of hazardous substances, which as a result of pyrolytic processes become ubiquitous in the environment and accumulate in water body sediments. Their isolation, quantitation and distribution patterns are the subject of this work, which in its first part deals with method development and testing (extraction, fractionation, solvent gradients, detector settings) and an extensive literature study on PAH patterns in environmental material. The second part affords data on PAH contents and patterns found in coastal surface sediments and some other matrices (water column, shore material). Results are presented in groups according to the regional provenance of samples and are discussed with respect to sources and preservation conditions. Data rely on RP-18-HPLC for standard PAHs and additional capillary GC measurements for other polycyclic and open chain compounds. Investigated sediments originate from the German North and Baltic Seas, from the central Norwegian Voering-Plateau and two Brazilian coastal areas. PAH contents ranged from about one (subrecent fine material) to 17 000 (harbour mud) ppb (total of 13 priority compounds according to U.S. EPA). Profiles of alkyl homologues and content ratios of PAHs with sceletons of differing environmental stability allowed to differentiate between samples, but not always to clearly discern petrogenic contributions from predominantly pyrogenic PAH assemblages. Perylene, biogenic alkylhydrochrysenes and -picenes as well as long-chain aliphatics with a terrestrial signature proved to be valid indicators of input sources and depositional features; the homologue profile of long-chain n-aldehydes appeared as a potential marker for sugar cane. A larger set of PAH compounds up to MW=302 as chemical parameters and the possible existence of a diagenetic relationship between perylene and hexahydroperylene are described and proposed for future testing
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
Natural and anthropogenic trace organics in coastal marine sediments: contents and patterns of polyaromatic hydrocarbons
No full textPolycyclic aromatic hydrocarbons (PAHs) are a class of hazardous substances, which as a result of pyrolytic processes become ubiquitous in the environment and accumulate in water body sediments. Their isolation, quantitation and distribution patterns are the subject of this work, which in its first part deals with method development and testing (extraction, fractionation, solvent gradients, detector settings) and an extensive literature study on PAH patterns in environmental material. The second part affords data on PAH contents and patterns found in coastal surface sediments and some other matrices (water column, shore material). Results are presented in groups according to the regional provenance of samples and are discussed with respect to sources and preservation conditions. Data rely on RP-18-HPLC for standard PAHs and additional capillary GC measurements for other polycyclic and open chain compounds. Investigated sediments originate from the German North and Baltic Seas, from the central Norwegian Voering-Plateau and two Brazilian coastal areas. PAH contents ranged from about one (subrecent fine material) to 17 000 (harbour mud) ppb (total of 13 priority compounds according to U.S. EPA). Profiles of alkyl homologues and content ratios of PAHs with sceletons of differing environmental stability allowed to differentiate between samples, but not always to clearly discern petrogenic contributions from predominantly pyrogenic PAH assemblages. Perylene, biogenic alkylhydrochrysenes and -picenes as well as long-chain aliphatics with a terrestrial signature proved to be valid indicators of input sources and depositional features; the homologue profile of long-chain n-aldehydes appeared as a potential marker for sugar cane. A larger set of PAH compounds up to MW=302 as chemical parameters and the possible existence of a diagenetic relationship between perylene and hexahydroperylene are described and proposed for future testing
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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