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The concentrations of two major elements and thirteen trace elements in 73 selected sherds of fine grey ware from the Iron Age and Roman period, excavated at Conimbriga, Santa Olaia and Tavarede, Portugal, were determined by instrumental neutron activation analysis. These concentrations were used to calculate distance matrices which were then subjected to cluster analysis employing SAHN and k-means methods, as well as to principal components analysis, to group the sherds according to the overall similarity of their compositional characteristics. The results showed that equivalent groupings appeared regardless of the taxonomic method used. Two major clusters were recognized corresponding to two different sites, namely Conimbriga and Santa Olaia, suggesting that the ceramics from these sites were made locally. No significant differences in compositional patterns were observed between iron age and roman sherds from Conimbriga.  相似文献   
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A problem which has arisen in discussions of an elm-disease explanation for the Neolithic elm decline has been the lack of fossil records of Scolytus scolytus (F.) (elm bark beetle), which is the main carrier of the fungus which causes the present epidemic of Dutch Elm Disease. Now, the discovery of wing cases of two individuals from elm decline deposits at Hampstead Heath, London, proves that the beetle was present in Britain during this episode. The deposits in which it occurs are described, and the various implications for elm disease causing, aiding or at least occurring during this stage of the early Neolithic are discussed.  相似文献   
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China has officially become a predominantly urban country, with over 50% of the population now registered as urban residents. Its urbanization process has been described as the most managed in human history. The Chinese government manages the building of new cities, regulates the housing of displaced people and controls squatters. As an historically poorer area, the west of China has been the target of ongoing efforts at infrastructural development. Describing urbanization as managed however masks the conflicts and contradictions involved in a process which is far from smooth. Although villagers are usually seen to be largely the powerless victims of these initiatives, it is clear that many try to take advantage of the situation, while others are unable to do so. Based on recent fieldwork and eight years of visits to one village undergoing urbanization, this article looks at the complex dynamics involved and at the moral battleground which they lay bare.  相似文献   
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