1,720,986 research outputs found
Characterization of buried inundated peat on seismic (Chirp) data, inferred from core information
No full textPeat horizons provide a wide range of critical environmental and direct archaeological information for both archaeologists and Quaternary geologists. At present, such data are typically obtained from terrestrial exposures or cores, and occasional offshore cores. These data can provide invaluable and detailed site-specific environmental information but require a relatively high spatial sampling strategy to provide more regional-scale information. Through a comparison of laboratory, in situ acoustic and sedimentary analyses, this paper presents evidence to suggest that peat buried in fine to medium grained, marine, siliciclastic sediments has an easily identifiable acoustic signature. The very low densities recorded by buried peats result in a distinct negative peak in the reflectivity series. Comparison of synthetic seismograms with in situ seismic data confirms that this negative peak can be easily identified from seismic profiles. Reanalysis of a decade of Chirp (sub-bottom) data, acquired from the Solent Estuary, indicates that possible extensive peat deposits, dating from the Late-glacial to early Holocene, can be traced at depth in this estuary using geophysical methods. The results of this study could be significant for future research into submerged landscape reconstructions
3D reconstruction of a shallow archaeological site from high resolution acoustic imagery: a case study (abstract of paper presented at AGU Fall Meeting, San Francisco, 5-9 Dec 2005)
Full text linkHigh resolution acoustic surveying for buried objects in the shallow waters of the inter-tidal to sub-tidal zone is a major challenge to many sectors of the marine surveying community. This is a consequence of a number of issues such as the relationship between water depth and acoustic acquisition geometry; problems of vessel induced bubble clouds reducing the signal-to-noise (SNR) ratio; and the necessity of high spatial survey accuracy in three-dimensions. These challenges are particularly acute for the marine archaeological community, who are frequently required to non-destructively investigate shallow-water (< 5 m) sites.
This paper addresses these challenges and demonstrates the potential of imaging buried objects in extremely shallow environments by describing a seamless marine archaeological and geophysical investigation of a buried shipwreck: Henry V’s ‘great flagship’, the Grace Dieu (1418). The site, located in the Hamble River (UK), is typically covered by 2-5 m of water, and is partially buried within muddy inter-tidal sediments. At exceptionally low tides, during the spring equinox, a few of the marginal timbers are exposed.
The marine survey utilised three different deployment methods of a Chirp system: two 2D Chirp systems, each emitting different frequencies and accompanied by different navigational systems (DGPS versus RTK), and a 3D Chirp system with RTK positioning capability. In all cases, the source was towed over the site using diver power. Close survey line spacing, accurate navigation and decimetre scale vertical and horizontal resolution acoustic data enabled the construction of a pseudo and full 3D image of this buried wreck site. This has been calibrated against known archaeological site investigation data and an RTK-GPS terrestrial survey.
This data has identified the true plan form and dimensions of the remaining segments of the vessel, supporting the assertion that it was the most significant naval design for over two centuries. It has also been possible to identify the presence of a horizon of incoherent timbers associated with the scuttling of the vessel
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
The use of a high-resolution 3D Chirp sub-bottom profiler for the reconstruction of the shallow water archaeological site of the Grace Dieu (1439), River Hamble, UK
No full textThe remains of Henry V’s flagship, the Grace Dieu, currently lie buried within the inter-tidal sediments of the River Hamble (S. England). Previous archaeological investigations have been hindered by difficult excavation conditions resulting in a poor understanding of the dimensions, shape and degradation state
of the hull’s deeper structure. This study therefore aimed to image, characterize and reconstruct the buried remains of this vessel using a high-resolution 3D acoustic sub-bottom Chirp system with RTK-GPS positioning capability. The accurate navigation and high-resolution data that were acquired enabled the construction of a full 3D image of the site that not only identified the remains of the wooden hull, but also features buried within it. In addition, the degradation state of these buried wooden remains were investigated by calculating reflection coefficients while a hypothetical larger reconstruction of the Grace Dieu’s hull was achieved, through the use of the ShipShape ship design software package. The results of this project demonstrate that (i) acoustic data can be used to successfully image buried wooden shipwrecks, (ii) artefacts are buried within the hull of the Grace Dieu, (iii) there is variation in the degradation state of the buried timbers, as calculated from the acoustic data, with the shell of the vessel
being moderately well preserved, and (iv) the Grace Dieu was a very large ship for its time (possibly over 60 m long and 16 m wide). The outcomes of this research not only have considerable implications for the management and monitoring
of submerged and buried archaeological sites but also for planning intrusive surveys, should they be required
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
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