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Most discussions of the relationship between class and political orientation assume a coherent and homogeneous class response. Here, the new middle class of professional workers is disassembled into constituent occupations. An analysis of political preference data by means of ‘correspondence analysis’ reveals a pattern which is consistent with a structural relationship between occupational experience and political preference.  相似文献   
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Compared to the geographic wasteland south of your border, geography appears to have fared well in Canada, both as a formal discipline extending our understanding by illuminating the human and physical worlds, and as a subject taught at all levels to create informed and aware citizens. I known you think much remains to be done, and perhaps things always look a bit greener on the other side of the hill, but I hope you will not mind my somewhat envious gaze. In fact, when I received the five volumes of the 'curriculum guideline' for geography, issued by the Ontario Ministry of Education for the intermediate and senior divisions of your high schools (ome 1988), my feelings were not so much envy as panic, a panic that rapidly induced something close to intellectual paralysis. Because in a moment I can only describe now as utterly weak and foolish, I started to read them, only to learn that your senior students 'analyze, interpret … explain … design and develop networks, systems and simulations that involve six or more variables' (ome 1988, A12).
In retrospect, I still think my panic was justified. After 30 years of hard post-doctoral work I have reached the point where I can think about the interactions of maybe three variables, but hardly the combinatorial possibilities of six. Such ineptness would mean that I might just squeeze into your tenth grade and from there slowly work my way over the next two years towards those Olympian heights of analytical thought where dwell Ontario's high school graduates.  相似文献   
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This paper extends a compartmental epidemiological model for HIV transmission and AIDS incidence to include hierarchical and expansion spatial diffusion. An implication of the resultant model is that hierarchical diffusion causes the large infection growth rates of densely populated areas at the top of the central places hierarchy to “chain” down and dominate small local growth rates during the exponential-growth phase of the epidemic. Also, hierarchical diffusion causes a high transient growth rate in the first few years of a local epidemic. The spatial compartmental model fits observed AIDS incidence spatial diffusion patterns in Ohio reasonably well.  相似文献   
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Many timber finds lack some or all of the outer, sapwood rings formed in the years just before felling. In order to estimate felling date once the outermost remaining ring has been dated, it is necessary to estimate the number of sapwood rings originally present. Methods doing this for oak are reviewed in the light of an intensive study of living trees at one site and an extensive study of 175 samples from living trees in North Wales and northwest England. Some methods reported in the literature are found to be invalid. A method reported by Hollstein (1965) is most reliable, with modifications for known variations in sapwood number with position in the tree. At present the best available estimate is that a value of 30 sapwood rings be used (95% confidence limits: 19–50).  相似文献   
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