1,720,956 research outputs found
The interaction of sedimentary organic matter with metals and organic pollutants in landfill barriers
No full textThis research examines the composition, sedimentary history and chemical properties of sedimentary organic matter [SOM] and its application in determining the content and source of heavy metals and hydrophobic organic contaminants [HOCs] and their fate in waste disposal sites. Previous research has utilised Oxford Clay (OxC) from across the outcrop. In this study a continuous shallow core of OxC and adjoining Kellaways Sand (KS) from Brogborough, UK was used. This avoided the influence of different sedimentary conditions, thereby reducing the problem of sample variability. Relationships have been made between sedimentary and organic petrology and SOM abundance and metals concentration (V, Cr, Co, Ni, Cu, Zn and As). The co-association/binding of different metals to different types of SOM components from the OxC was shown to be dictated by the depositional environment. The organic rich parts (Total Organic Carbon (TOC) > 5 %) of the OxC displayed positive correlations between the elements V, Co, As and total pyrite % (p<1.1E-3, ? >0.7); however, there was an apparent negative correlation with TOC % (p<4.3E-5, ?<-0.4). This may be because of: 1) the rapid accumulation of the OM reduced the time for development of the pyrite (Ave. dia. =5.3?m, SD=2.4); and/or 2) the insufficient concentration of Fe to allow pyrite formation. This could be due to the high sedimentation rate that accelerates the accumulation of OM, which prevents its decomposition in the water column, as well as reducing the time for pyrite that is entrapped in the marine snow to capture metals from seawater during its settlement. Cu has a significant positive correlation with TOC (p=1.9E-2, ?=1.3), which could be the consequence of Cu being an essential element in OM. The OxC with a lower OM content (TOC < 5 %) showed a different distribution of metals. V, Cr and Cu found in OM was found to have a significant positive correlation with TOC (p<2.9E-2, ?>0.05). The Kellaways Sand core showed that the V, Co, Ni, Cu, Zn and As had a strong connection both with TOC (p<1.6E-3, ?=0.03~37.3) and pyrite (p<4.9E-3, ?=0.23~5.5), suggesting that both OM and pyrite were major metal sinks in Kellaways Sand. The more significant positive correlation between V, Cr and pyrite compared to V, Cr and TOC implies that pyrite contains more V and Cr than did TOC. Other studies used the OxC from Bletchley, the Kimmeridge Clay (KC) from Kimmeridge Bay, Dorset, and Tertiary mud (Wittering Formation-WF) from Whitecliff, Isle of Wight due to their distinctive OM characteristics (AOM rich and/or phytoclast rich). Organic material was isolated for identification and analysis using a novel extraction method (heavy liquid extraction) and traditional methods involving HF digestion. These organic materials were then used to determine influences of extraction on HOCs (toluene and naphthalene) sorption and desorption. Organic petrology classification was applied to identify the various types of isolated OM. AOM from KC displayed a higher sorption capacity (Kd=6,481, 59,670; for toluene and naphthalene, respectively) compared to literature values. AOM rich sorbent extracts demonstrated a higher absorption capacity than the phytoclasts rich sorbents (e.g. WF, Kd=219, 20,661; for toluene and naphthalene, respectively). However, the phytoclast rich sorbent showed a higher sorption/desorption hysteresis capacity for toluene than AOM. Implications of results in landfill design/risk assessment and modelling are discussed. <br/
The influence of solid-phase organic carbon on the sorption of hydrophobic organic pollutants in landfill barriers, UK
No full textThe Oxford Clay from Bletchley, the Kimmeridge Clay from Kimmeridge Bay, Dorset, and Tertiary mud (Wittering Formation) from Whitecliff, Isle of Wight, United Kingdom were used as sorbent samples because of their distinctive organic material characteristics (Amorphous organic matter rich and/or phytoclast rich). Organic material was isolated for identification and analysis using a non-acid extraction method (heavy liquid) extraction and traditional methods involving HF digestion. These organic materials were then used to determine influences of extraction on hydrophobic organic contaminants, (toluene and naphthalene) sorption. Organic petrology classification was applied to identify the various types of isolated organic material. Amorphous organic matter from the Kimmeridge Clay displayed a higher sorption capacity (Sorption–desorption distribution coefficient (Kd), Kd = 6,481, 59, 670; for toluene and naphthalene, respectively) compared to literature values. Amorphous organic matter-rich sorbent extracts demonstrated a higher absorption capacity than the phytoclast-rich sorbents (e.g., Wittering Formation, Kd = 219, 10, 134; for toluene and naphthalene, respectively). Implications of results in landfill design/risk assessment and modelling are discussed
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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