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961.
Focus in this discussion is on research designed to examine human fertility variation in 59 Pennsylvania counties in 1850 and 1860. The research goes beyond previous historical studies in examining the relationship between land quality and fertility and in separating the possible impacts of settlement from the availability of land for agricultural purposes. The measure of human fertility used in the analysis was the child-woman ratio, defined as the number of children aged 0-4/1000 white women aged 15-49. In 1850 the child-woman ratio ranged from 488-889. The child-woman ratio fell slightly between 1850 and 1860, and county level variation was reduced. Yet, Pennsylvania counties varied substantially in fertility levels during this period. The range between the highest and lowest fertility countries was over 400 children in 1850 and almost 350 in 1860. The set of agricultural variables displayed expected differences at the 2 time periods. The excess demand for farmsites increased between 1850 and 1860, while the variation in demand decreased by over one-half, reflecting additional settlement within all acres of the state. The settlement ratio increased over the decade; the sex ratio declined, most likely in response to outmigration westward. The agricultural variables were all negatively related to the child-woman ratio and were statistically significant, except for the labor/acre variable. The strongest correlation in 1850 was between the excess demand for farmsites and fertility. This coefficient indicated that the greater the excess demand for farmsites, the lower the child-woman ratio. This relationship was attentuated somewhat for 1860, yet it continued to be negative and statistically significant. The socioeconomic and demographic variables were all related to fertility in the expected direction, but only 5 of the 7 correlations were statistically significant in 1850 and 6 in 1860. The settlement ratio, sex ratio, percent urban, distance to urban place, and the measure of female age composition were all significantly related to fertility in 1850 and 1860. The study results support the growing body of research which has identified agricultural opportunity as a significant factor in fertility in rural areas of 19th century America. The findings also suggest that the importance of agricultural opportunity extended beyond the frontier period. 相似文献
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The paper analyzes the limiting case for a modified Yule-Simon model of city growth. The aim of the paper is primarily to reintroduce geographers to the notion of a closed system of cities, i.e., a system of cities where the aggregate population is stationary in size. The Yule-Simon model, while successful in dealing with the observed properties of open systems, is seen to break down for closed systems. Moreover, incorporating Simon's assumptions regarding intercity migration into the model produces implausible results. Also, the traditional approach of employing entropy-maximizing procedures assumes a certain pattern of intercity migration. This pattern, while not inherently implausible, does present features which are questionable. The authors conclude that an adequate theory for closed systems has yet to be developed. 相似文献
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Fired rock-crystal was found within the matrix of a Balangodese (pre-Vedda) burial in a Mesolithic midden in Ceylon; thermoluminescent measurements indicated a date of about 7000 years before present. 相似文献
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