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New ages for the post-Howiesons Poort,late and final Middle Stone Age at Sibudu,South Africa 总被引:1,自引:0,他引:1
Zenobia Jacobs Ann G. Wintle Geoffrey A.T. Duller Richard G. Roberts Lyn Wadley 《Journal of archaeological science》2008
Optically stimulated luminescence (OSL) measurements are reported for single grains of quartz from deposits within Sibudu rock shelter. Such measurements enable rejection of unrepresentative grains and application of the finite mixture and central age models to obtain the most reliable age estimates. Three types of single-grain equivalent dose (De) distributions were observed: one sample represented a single dose population, three samples indicated mixing between Iron Age (IA) and Middle Stone Age (MSA) deposits, and 10 samples (in addition to the three mixed samples) showed scattered distributions. The latter type resulted from differences in the beta dose received by individual grains. For these samples, the beta doses were modelled and adjusted accordingly. Ages for the 14 samples collected from MSA deposits post-dating the Howiesons Poort (HP) resulted in three age clusters, which are stratigraphically consistent with the three informally named cultural phases at Sibudu: namely, the post-HP, late MSA and final MSA. Weighted mean ages of 58.5 ± 1.4 ka, 47.7 ± 1.4 ka and 38.6 ± 1.9 ka were calculated for these phases, respectively. The three phases were separated by two occupational hiatuses with durations of 10.8 ± 1.3 ka and 9.1 ± 3.6 ka. We hypothesise that the punctuated presence of humans at Sibudu was determined by large-scale fluctuations in climate during oxygen isotope stage (OIS) 3, which resulted in alternating wet and dry periods. Phases of occupation correspond to wet periods when fresh water was available in the Tongati River, whereas intervals of site abandonment correspond to dry periods when people were forced to migrate in search of a reliable source of fresh water. Where people migrated to, remains unresolved. 相似文献
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Using a set of interregional input‐output tables built by Guilhoto (1998) for 1995 for two Brazilian regions (Northeast and rest of the economy), the methodology developed by Sonis, Hewings, and Miyazawa (1997) is applied in the construction of a series of linkages such that it is possible to examine, through the nature of the internal and external interdependencies, the structure of trading relationships between the two regions. The methodology uses a partitioned input‐output system and exploits techniques that produce left and right matrix multipliers of the Leontief Inverse. This procedure facilitates the classification of the types of synergetic interactions within a preset pairwise hierarchy of economic linkages subsystems. In general, the results show that the Northeast region has a greater dependence on the rest of the economy region than the rest of the economy has on the Northeast region, and at the same time the rest of the economy region seems to be more developed as it presents a more complex productive structure than the Northeast region. 相似文献
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Geoffrey Warner 《International affairs》2002,78(4):869-882
Based upon recently published volumes of French diplomatic documents, this review article examines the course of the negotiations for British entry into the European Economic Community from 1961 to 1963 and the reasons why France vetoed Britains application. It is clear that even before the British government launched its application, the French government was aware of the threat it posed to the cohesion of the Community and to French interests. It therefore pursued tactics of delay. The British, who were in a hurry to join, vainly sought to convince the French of their conversion to the Gaullist conception of a con–federal Europe that would be independent of both the Soviet Union and the United States, even dangling the prospect of nuclear cooperation before President de Gaulle. The latter's position inside France was relatively weak until he won a referendum on the direct election of the president in October 1962 and his party triumphed in the legislative elections the following month. De Gaulle then felt secure enough to tell Prime Minister Macmillan quite bluntly at their Rambouillet meeting on 15–16 December 1962 that he did not believe that Britain was ready for EEC membership. He had thus already made up his mind to exclude Britain before the Nassau agreement between President Kennedy and Mr Macmillan in which the former agreed to supply Britain with Polaris nuclear missiles, although this agreement confirmed his belief that Britain was excessively dependent upon the United States. Although economic questions—particularly those relating to the system of agricultural support and to Britain's request for special concessions to Australia, Canada and New Zealand—did play an important part in de Gaulle's decision, it is clear that political factors were uppermost in his mind. He did not want either a diluted Community or one in which there was a possible rival to French leadership. 相似文献
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