1,721,072 research outputs found
Critical loads of acid deposition for UK freshwaters: Report of the Critical Loads Advisory Group, sub-group on Freshwaters, for the UK Department of the Environment
Get PDFFollowing a decade of intensive research on the causes, mechanisms and extent of surface water acidification in the United Kingdom, and the general acceptance that acidification is a major environmental problem, attention is now focused on ameliorative strategies and their potential success. Within the Department of the Environment's research programme this comprises two components: defining and mapping the critical loads of acidity for freshwaters, and monitoring selected freshwaters to evaluate the long-term benefits of reducing acidifying emissions from power stations. This report presents the interim results of the first of these, the critical loads programme. Approximately 1600 water bodies throughout the UK have been sampled and analysed to enable critical load values for the most sensitive sites within grid squares to be derived and mapped as required by the UNECE (United Nations Economic Commission for Europe). A validation study of these primary survey data is now being carried out. When complete, new critical load maps will be published showing sites where modifications are needed. In this report we refer only to acidity that is attributable to sulphur deposition. However, the acidification status of some freshwaters is also influenced by nitrogen deposition. For these sites the values shown on the critical load exceedance maps will be under-estimates. Current research is addressing this issue, and future critical load exceedance maps will show values for total acidity (sulphur+ nitrogen}. All the work presented here has benefitted from discussion within the DoE's Critical Loads Advisory Group (CLAG) and the CLAG Sub group on Freshwaters. I should like to thank members of both those groups for their contributions and for their help over the last four years. I should also like to thank the DoE for funding
Decadal and century-scale climate variability in tropical Africa during the past 2000 years
No full textGoing 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
The acidification of Scottish Lochs and the deprivation of critical sulphur loads from palaeolimnological data
Get PDFA decade ago very little was known about acid lochs in Scotland. The implicit
assumption was that they were largely free from pollution. In recent years the position
has changed and we now have large bodies of data on the chemistry and biology of
upland lochs (Harriman et al. 1986, Maitland et al. 1987, Battarbee et al. 1988) and
clear evidence for the recent acidification of many sensitive sites (Flower and Battarbee
1983, Battarbee et al. 1985, Flower et al. 1987, Battarbee et al. 1988)
Diatom analysis of River Thames foreshore deposits exposed during the excavation of a Roman waterfront site at Pudding Lane, London. Report for the Department of Urban Archaeology, Museum of London
Get PDFEighty-seven diatom taxa including marine, brackish, and freshwater forms were identified from foreshore sediments accumulated against pre-AD 100 quay structures exposed during the excavation of an early Roman waterfront site in the city of London. The spectra indicate that the Roman port was probably established close to the tidal head of the river
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
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