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51.
In the past decade Tobler has provided an innovative cartographic presentation of migration flows. The central theme of this research has been to utilize detailed migration data to reveal the underlying structures of migration flows. Even though the analyses are not explanatory models of migration exchanges, the application of these techniques to migration flows over time and across different spatial scales provides a visual generalization of often extremely complex flows. The application of his techniques at two spatial scales for the Netherlands illustrates both the strengths and weaknesses of migration force fields for the analysis of migration. 相似文献
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Charcot-Marie-Tooth disease is a hereditary motor and sensory neuropathy first described in 1886. Our increasing knowledge of this disease correlates well with the development of methods used in neurology over the past 100 years. Although its physiopathology and treatment is still not fully understood, current developments in techniques are opening the way to future discoveries. We have divided its history into three theoretical periods: the first from 1886 to 1956, which was devoted to clinical and pathological study of the disease; the second from 1956 to 1982, which saw the development of electromyography in the investigation of neuromuscular diseases; and the last and current period based upon genetic research, using the methods of molecular biology. 相似文献
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Michael A. Nelson 《Journal of regional science》1992,32(1):39-53
ABSTRACT. The proposition that a decentralized structure of local governments can effectively constrain public sector growth is empirically investigated. Data on Swedish municipal sector size for the 1942–87 period are analyzed within the context of a median voter model. The results indicate that decentralization, measured by the number of units of local government serving a given population, constrains the influence of institutional factors (e.g., rent seeking, bureaucracy) on local budgets as long as these units exceed some minimal threshold size. The findings support the view that communities should be given the flexibility to determine their own ideal pattern of local governments. 相似文献
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Three rare Himyaritic coins found in the territory of the ancient Hadramawt kingdom are published for the first time. Two of the coins bear the name of the king,'Amdan Bayyin, while the third has the name of Tha'ran Ya'ub. 相似文献
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