1,720,993 research outputs found
The application of sedimentary ancient DNA analysis to archaeological sediments for the reconstruction of palaeoenvironments
No full textSedimentary ancient DNA (hereafter sedaDNA) analysis is now a common method employed for palaeoenvironmental reconstruction in studies of paleoecology. It is most often applied as a palaeoecological technique when analysing lake sediments, marine sediments or permafrost in Arctic or Sub-Arctic locations, as these have proved favourable contexts for DNA preservation and stratigraphic stability. However, sedaDNA analysis is also beginning to be more widely applied to fluvial and terrestrial environments in temperate locations, which increase the opportunity for application of the technique to archaeological sites and sediments. If such applications can be shown to be successful, then sedaDNA analysis will be a powerful tool for understanding the archaeological record.This thesis focuses on the use of sedaDNA metabarcoding, and in one instance shotgun sequencing, to better understand the palaeoenvironments at significant UK Prehistoric archaeological sites. The three sites are: Blick Mead, Wiltshire, Killerby, North Yorkshire, and Seven Springs, Martlesham, Suffolk. Applications of sedaDNA to terrestrial contexts are not without their specific challenges and limitations, which will be discussed in detail later in this text, the method is therefore applied in conjunction with more traditional proxies such as plant macrofossils, mollusca, coleoptera, and pollen. These methods complement and, in some cases, overlap with the genetic evidence to provide a more complete assessment of biodiversity at any given site. As such, at each location chosen for study, sedaDNA was part of a multiproxy approach.In the three papers presented in this thesis, sedaDNA was shown to be preserved fairly well in temperate lacustrine, fluvial and terrestrial sediments and corroborated much of the existing archaeological faunal and lithic evidence found at each site. At all three sites, the molecular evidence increased the number of taxa than would have otherwise been found using only pollen and/or macrofossil data. SedaDNA improved reconstructions of floristic diversity, and sedaDNA was able to detect plant taxa that are frequently missing or underrepresented in other environmental and faunal records, such as aquatic plants and insect pollinated trees. This allowed a re-evaluation of archaeological hypotheses at each site, leading to insights surrounding site selection strategies and the exploitation of local floral and faunal resources.The findings from this thesis also highlighted the importance of careful site selection when sampling for sedaDNA in terrestrial environments. At both Blick Mead and Killerby, the sampled horizons were largely protected from post-depositional mixing of sediment. At Martlesham, dating provided evidence of a mixed context within the peat, but the addition of shotgun sequencing and map-damage assessment confirmed that the sedaDNA found was ancient DNA. Furthermore, the preservation of DNA in peatland was found to be variable, with limited species representation at Killerby but a rich community seen from the peatland at Martlesham. To detect such problematic factors, the papers from this thesis showed that sedaDNA studies in terrestrial environments required a thorough chronological model and understanding of stratigraphic depositional environments.At the two sites from Southern England, Martlesham and Blick Mead, sedaDNA analysis suggested the presence of rich floodplain carr-woodland and meadow environments. At Blick Mead, this fed into wider questions of Mesolithic-Neolithic transitional vegetation disturbance. Whilst the large plant assemblage found at Martlesham of over 60 taxa revealed the species richness of an Early Neolithic environment in SE England, and the data suggested use of the area for forest farming. The site from North Yorkshire, Killerby, showed evidence of a large post-glacial lake that underwent hydroseral succession in the beginning of the Holocene. The later Cladium-sedge fen that developed provided the environment for Mesolithic archaeological activity found at the site, either via timber constructions or the exploitation of sedges for fuel and consumption.Overall, the sites mentioned in this project show the potential of this novel method of environmental reconstruction for use of environmental archaeology. The findings of the three papers improved understanding of Lateglacial vegetational change, Late Mesolithic forest coverage and Neolithic farming practices, and the project as a whole outlined where further study using sedaDNA could benefit outstanding research questions. However, the methodological problems identified, such as the overrepresentation of local species, poor representation of mammal taxa, variable preservation in different sedimental contexts and possibility of contamination, mean that sole applications of sedaDNA are not yet recommended at archaeological sites for best practice. Instead, sedaDNA analysis, in particular metabarcode data, is best used as an accessible and powerful complementary environmental proxy for application in an increasing variety of archaeological sedimentary contexts.<br/
Dataset in support of the Southampton doctoral thesis 'The application of sedimentary ancient DNA analysis to archaeological sediments for the reconstruction of palaeoenvironments'
No full textSedaDNA Plant and Mammal Data
Metabarcoding plant and mammal DNA data before post-identification filtering for Blick Mead, Martlesham and Killerby.</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
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
- …
