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991.
992.
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
993.
994.
Some new methods for the topologic classification of channel networks are proposed. These methods are all based on the concept of topologic path length, or number of links from the network outlet to a junction or source. Two parameters, the total path length (sum of all path lengths) and the diameter (largest path length) are shown to be useful in network analysis. Some advantages of these parameters are that they are easy to measure, have straightforward topologic interpretations, and are closely related to important geometric measures. Moreover, they are capable of explaining various empirical geomorphic “laws,” such as the 0.6 power relation between mainstream length and area. 相似文献
995.
996.
A comparative study is made of the thermoluminescence (TL) of terracottas of the Renaissance era and some known limitations of such ware dating to the middle of the last century. The data shows that conclusions on authenticity of an unknown work can be reliably obtained using this scientific method. Also examples are presented of accurate dating of genuine terracottas despite a lack of knowledge about the environmental circumstances of each piece's archaeological past. 相似文献
997.
A technique is described by which the spatial distribution of uranium as well as of thermoluminescent minerals can be examined in the same archaeological sample. The uranium distribution is replicated on an aluminized plastic film with the help of a ‘spark counter’following reactor-irradiation of the sample, while the TL pattern is photographed directly from a γ-irradiated sample. Implications for dating from such a comparative examination are discussed for certain pottery and flint samples. 相似文献
998.
999.
1000.
S. J. FLEMING 《Archaeometry》1973,15(1):13-30
A thermoluminescent (TL) glow-curve peak occurs around 110°C for the mineral quartz. Its sensitivity may be changed by application of a radiation dose (termed the pre-dose) followed by a heating of the quartz to 500°C: heating alone causes no sensitivity change. The enhancement observed (measured relative to the sensitivity of the peak prior to heating) is a measure of the magnitude of the pre-dose. For quartz extracted from pottery the sensitivity enhancement induced by laboratory heating records a natural pre-dose, i.e. the accumulated dose experienced during archaeological burial. The latter quantity is used in TL age-determination and a test programme is reported on the application of the pre-dose dating method to sites covering the Roman era in Britain forward to modern times. 相似文献