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This study examines preservation of microfossils identified as introduced Ipomoea batatas in soils from northern New Zealand. Starch grains and xylem cells showed highly variable preservation, from good to extremely poor. For starch grains, the latter included brown-staining, expansion and distortion of the grain and vacuole, loss of the Maltese cross, pitting, cracking, fragmentation and disintegration. Degraded xylem showed similar brown-staining, occasional cracking, cross-wise fragmentation, with wall pits becoming progressively less visible or showing distortion, expansion and coalescence. 相似文献
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Schneider WH 《Journal of the history of medicine and allied sciences》2003,58(2):187-224
This article examines the introduction of blood transfusion into general practice from the end of the First World War to the Second World War. Developments during most of this period were not the result of new discoveries but rather the spread of ideas and the establishment of donor organizations to secure an adequate blood supply. The identification, testing, and organization of potential donors were done in a wide variety of settings that reflected differences in political and cultural experiences. At the end of the 1930s, with war approaching, the resolution of problems with storage of blood and the discovery of new techniques for separating and storing plasma dramatically changed transfusion practice. Thus, the innovations of the Second World War were very much based on the development of broad donor organizations plus the new technical discoveries that had occurred during the interwar period. 相似文献
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Mark W. Hauser Christopher R. DeCorse 《International Journal of Historical Archaeology》2003,7(1):67-98
Local earthenware associated with enslaved African populations in the Americas, variously called Colono-Ware, Afro-Caribbean Ware. Yabbas, and Criollo ware, has received considerable attention from researchers. What unifies this disparate group of ceramics is not method of manufacture, design and decoration, or even form and function but the association or potential association with African diaspora populations. The ceramics incorporate some skills and techniques possibly brought by African potters to the Americas, as well as skills reflecting European and Native American traditions, and local adaptations in form, function, and manufacture. Analogies linking African ceramic traditions to American industries have at times been employed uncritically and have relied on generalized characteristics to infer overly specific meanings. With particular reference to low-fired earthenwares from Jamaica, this paper examines the historical and cultural context of these ceramics and the methodological and theoretical problems faced in their interpretation. 相似文献
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RESIDENTIAL SORTING AND ENVIRONMENTAL EXTERNALITIES: THE CASE OF NONLINEARITIES AND STIGMA IN AVIATION NOISE VALUES
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This paper explores the sorting process in response to differing levels of aviation noise exposure in a housing market. Spatiotemporal hedonic pricing (HP) and stated choice (SC) results reflect nonlinearities and stigma. The HP models reveal nonlinear noise depreciation increasing from 0.40 to 2.38 percent per decibel as noise increases, while the SC noise values are lower in an area with high long‐term noise exposure. These nonlinearities are attributed to the spatial sorting of noise tolerant individuals. HP results from the same “noisy” area show a “stigma” from noise during the first year after the complete removal of aviation noise. 相似文献