排序方式: 共有114条查询结果,搜索用时 15 毫秒
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Ralph E. J. Boerner Michael N. DeMers John W. Simpson Francisco J. Artigas Alejandra Silva Leslie A. Berns 《Geographical analysis》1996,28(1):56-66
This study examined landcover change during 1940–1988 in two contiguous landscapes of approximately 12,400 hectares in central Ohio, USA: an inertial till plain area and a more dynamic moraine area. Agriculture dominated both landscapes throughout, however, the cover of natural vegetation and urban-suburban development increased over time on the moraine while natural vegetation decreased and agriculture increased on the till plain. Markov process models for landcover change were constructed for three 14–17-year time intervals and for the entire forty-eight-year study period. Probabilities of self-replacement for agricultural lands (0.91–0.97) were higher and those for forests (0.54–0.65) lower than those reported for other landscapes. Predictions of landcover percentages for fifty years in the future were made using Markov process models derived from actual cover changes in 1940–1957, 1971–1988, and 1940–1988. All three models produced similar predictions for the inertial till plain area. In contrast, the three models' predictions differed considerably for the moraine area. Only the 1971–1988 transition matrix was sensitive to increases in urbanization and reforestation which began on the moraine in the 1970s. These results indicate that reliance on lengthy study intervals and net rates of change can obscure spatial and temporal patterns of landcover change that are caused by natural and socioeconomic factors operating on shorter time scales. 相似文献
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Navigating the Fault Lines: Race and Class in Philadelphia's Solidarity Economy 总被引:1,自引:0,他引:1
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In debates over post‐capitalist politics, growing attention has been paid to the solidarity economy (SE), a framework that draws together diverse practices ranging from co‐ops to community gardens. Despite proponents’ commitment to inclusion, racial and class divides suffuse the SE movement. Using qualitative fieldwork and an original SE dataset, this article examines the geospatial composition of the SE within the segregated geography of Philadelphia. We find that though the SE as a whole is widely distributed across the city, it is, with the exception of community gardens, largely absent from poor neighborhoods of color. We also identify SE clusters in racially and economically diverse border areas rather than in predominantly affluent White neighborhoods. Such findings complicate claims about the SE's emancipatory potential and underscore the need for its realignment towards people of color and the poor. We conclude with examples of how the SE might more fully address racial injustice. 相似文献
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H. Barnard W. Z. Wendrich A. Winkels J. E. M. F. Bos B. L. Simpson R. T. J. Cappers 《Journal of Field Archaeology》2016,41(1):84-100
Excavations in the arid regions of Egypt provide insight into the many types and uses of mudbrick architecture. Upon exposure the inherently unstable building material decays rapidly, resulting in severe loss or complete destruction of once well-preserved buildings. The preservation of mudbrick structures is relatively complicated and expensive. Research has focused on the circumstances that enable preservation and the influence of climate and weather over time. Conservation treatments should address these two processes as soon as possible after exposure of the structures. Our assessment of a range of conservation methods leads to the conclusion that reburial is among the least objectionable method of preservation, despite its drawback of returning the excavated buildings to a situation where they are invisible to both researchers and the public. 相似文献
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Marianna Shreve Simpson 《Iranian studies》2011,44(4):596-601