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171.
Experimental tests on four full-scale exterior unreinforced reinforced concrete (RC) beam-column joints, representative of the existing non-conforming RC frame buildings, are carried out. The specimens have different longitudinal reinforcements (plain or deformed) and they are designed in order to be representative of two typical design practices (for gravity loads only or according to an obsolete seismic code). Different failure modes are observed, namely joint failure with or without beam yielding. The local response of the joint panel is analyzed. The different joint deformation mechanisms and their contribution to the deformability and to the energy dissipation capacity of the sub-assemblages are evaluated.  相似文献   
172.
Middle pleistocene adaptations in Central Europe   总被引:1,自引:0,他引:1  
The biological evolution documented in the fossil and archaeological record of Central Europe between about 700,000 and 100,000 years ago reflects the transition fromHomo erectus to the earliestHomo sapiens. These populations created different types of industries, ranging from assemblages of small artifacts and industries with simple pebble tools to standardized units such as the Evolved Acheulean and the Early Mousterian. The industries of the Last Interglacial (Taubachian) show some regression in technological standardization and a reappearance of small artifacts. Other aspects of cultural adaptation (settlements, dwellings, hunting activity, symbolic and aesthetic expressions) are also summarized. It is suggested that the impact of climate and climatic changes on human settlement and behavior was greater in Central Europe (where two glaciations advanced from both north and south) than in the Mediterranean and Western Europe. The general trend of cultural veolution was toward greater technological and social complexity, but its course was not unilinear.  相似文献   
173.
The development of a survey strategy for archaeological sites of Pleistocene age through the application of historical geomorphology is described. Geomorphic contexts in the northern foothills of the Alaska Range with potential for producing archaeological remains from the 30,000-12,000 bp interval were identified and subjected to exploratory testing. Contexts were selected on the basis of estimated age, palaeotopographic setting and geomorphic history, and included glaciofluvial outwash, side-valley fan alluvium, loessic colluvium and primary frozen loess. Testing was eventually focused on formerly deflated terrace surfaces—a potential source area for artifacts redeposited in the outwash or alluvium. Although the results of the exploratory testing were negative, and archaeological sites in the region remain confined to loess deposits of the later Late Glacial (12,000-10,000 bp), discoveries in other parts of Beringia suggest that sites of earlier Late Glacial age (14,000-12,000 bp) are also likely to be present in the foothills. The application of historical geomorphology in surveys for early prehistoric sites is essential for effective use of available resources and for maximizing the significance of the results (positive or negative).  相似文献   
174.
中国共产党在 80年光辉历程中经历了以 1 935年遵义会议和 1 978年十一届三中全会为标志的两次伟大历史转折。两次伟大历史转折都产生了巨大的作用和深远的影响 ;两次伟大历史转折都发生在重大的历史关头 ,同时又都是经过较为充分的准备 ,在政治上、组织上条件已经成熟的情况下发生的 ;两次伟大历史转折都是通过发扬党内民主、开展党内斗争来实现 ;两次伟大历史转折以后 ,都还经过了一个相当时间的后续的发展过程 ,转折的成果才得到巩固 ,转折的任务才全部完成。  相似文献   
175.
J. Tóth  I. Almási 《Geofluids》2001,1(1):11-36
The ≈ 40 000 km2 Hungarian Great Plain portion of the Pannonian Basin consists of a basin fill of 100 m to more than 7000 m thick semi‐ to unconsolidated marine, deltaic, lacustrine and fluviatile clastic sediments of Neogene age, resting on a strongly tectonized Pre‐Neogene basement of horst‐and‐graben topography of a relief in excess of 5000 m. The basement is built of a great variety of brittle rocks, including flysch, carbonates and metamorphics. The relatively continuous Endr?d Aquitard, with a permeability of less than 1 md (10?15 m2) and a depth varying between 500 and 5000 m, divides the basin's rock framework into upper and lower sequences of highly permeable rock units, whose permeabilities range from a few tens to several thousands of millidarcy. Subsurface fluid potential and flow fields were inferred from 16 192 water level and pore pressure measurements using three methods of representation: pressure–elevation profiles; hydraulic head maps; and hydraulic cross‐sections. Pressure–elevation profiles were constructed for eight areas. Typically, they start from the surface with a straight‐line segment of a hydrostatic gradient (γst = 9.8067 MPa km?1) and extend to depths of 1400–2500 m. At high surface elevations, the gradient is slightly smaller than hydrostatic, while at low elevations it is slightly greater. At greater depths, both the pressures and their vertical gradients are uniformly superhydrostatic. The transition to the overpressured depths may be gradual, with a gradient of γdyn = 10–15 MPa km?1 over a vertical distance of 400–1000 m, or abrupt, with a pressure jump of up to 10 MPa km?1 over less than 100 m and a gradient of γdyn > 20 MPa km?1. According to the hydraulic head maps for 13 100–500 m thick horizontal slices of the rock framework, the fluid potential in the near‐surface domains declines with depth beneath positive topographic features, but it increases beneath depressions. The approximate boundary between these hydraulically contrasting regions is the 100 m elevation contour line in the Duna–Tisza interfluve, and the 100–110 m contours in the Nyírség uplands. Below depths of ≈ 600 m, islets of superhydrostatic heads develop which grow in number, areal extent and height as the depth increases; hydraulic heads may exceed 3000 m locally. A hydraulic head ‘escarpment’ appears gradually in the elevation range of ? 1000 to ? 2800 m along an arcuate line which tracks a major regional fault zone striking NE–SW: heads drop stepwise by several hundred metres, at places 2000 m, from its north and west sides to the south and east. The escarpment forms a ‘fluid potential bank’ between a ‘fluid potential highland’ (500–2500 m) to the north and west, and a ‘fluid potential basin’ (100–500 m) to the south and east. A ‘potential island’ rises 1000 m high above this basin further south. According to four vertical hydraulic sections, groundwater flow is controlled by the topography in the upper 200–1700 m of the basin; the driving force is orientated downwards beneath the highlands and upwards beneath the lowlands. However, it is directed uniformly upwards at greater depths. The transition between the two regimes may be gradual or abrupt, as indicated by wide or dense spacing of the hydraulic head contours, respectively. Pressure ‘plumes’ or ‘ridges’ may protrude to shallow depths along faults originating in the basement. The basement horsts appear to be overpressured relative to the intervening grabens. The principal thesis of this paper is that the two main driving forces of fluid flow in the basin are gravitation, due to elevation differences of the topographic relief, and tectonic compression. The flow field is unconfined in the gravitational regime, whereas it is confined in the compressional regime. The nature and geometry of the fluid potential field between the two regimes are controlled by the sedimentary and structural features of the rock units in that domain, characterized by highly permeable and localized sedimentary windows, conductive faults and fracture zones. The transition between the two potential fields can be gradual or abrupt in the vertical, and island‐like or ridge‐like in plan view. The depth of the boundary zone can vary between 400 and 2000 m. Recharge to the gravitational regime is inferred to occur from infiltrating precipitation water, whereas that to the confined regime is from pore volume reduction due to the basement's tectonic compression.  相似文献   
176.
Ceramic petrography can be an effective method for studying demographic shifts and the possibility of migration into a region. This is based on the principle that ceramic manufacturing technology is resistant to change over time, while form and decoration can change quickly even in times of demographic continuity. As such, sudden shifts in raw material preparation and methods of pottery manufacture may be indicative of the arrival of new people in a region. The manufacturing characteristics indicative of such a demographic change are observable and measurable microscopically. Petrography was used to describe and measure paste characteristics of 114 Middle Copper Age, Late Copper Age, Early Bronze Age, and Middle Bronze Age sherds from the Körös region of the Great Hungarian Plain to determine if changes in manufacturing techniques accompanied changes in ceramic form and decoration at the beginning of the Late Copper Age Baden period (ca. cal. 3500 B.C.). A comparison of the petrographic results from the cultural phases showed that little manufacturing and technology change occurred during the time period covered by the study. Migration of new people into the region is therefore not supported, and changes in ceramic form and decoration associated with the Late Copper Age occurred during an extended period of demographic continuity.  相似文献   
177.
Current research themes relating to prehistoric Central Asian pastoralism are discussed, and the Neolithic to Bronze archaeological sequence in Kazakhstan is briefly outlined. The results of new faunal analyses of six later Bronze Age sites in Central and Northern Kazakhstan are presented. These studies are based upon the analysis of 63,529 bone fragments, of which 27,023 were identifiable to species and element. These assemblages are compared with 16 other sites in Central and Northern Kazakhstan, and the Trans-Ural region. The herd structures at the final Bronze Age site of Kent are discussed in detail. Analyses of absorbed lipid residues from four sites are also presented. In total, 140 pottery sherds were analysed, of which 73 provided sufficient residues for stable isotope ratio determinations. It is concluded that species proportions are highly variable regionally. Cattle are most prevalent in the forest steppe zone, whilst caprines become more common in semi-arid steppe regions. Proportions of horse are particularly variable, even within environmentally similar areas. Lipid residue results indicate the high prevalence of ruminant dairy products in pottery vessels, whilst faunal data from Kent suggests that cattle husbandry might have been particularly focussed on milk, in comparison with sheep and goats. The significance of horses within prehistoric pastoralism is discussed.  相似文献   
178.
This paper provides a review of the practices and tensions informing approaches to professional development for early career academic geographers who are teaching in higher education. We offer examples from Britain, Canada, Nigeria and the USA. The tensions include: institutional and departmental cultures; models that offer generic and discipline-specific approaches; the credibility of alternative settings for professional development in teaching and learning; the valuing of professional development and of teaching in academic systems of reward and recognition; and the challenges of balancing professional and personal life. We summarize concepts of good practice and suggest opportunities for future research.  相似文献   
179.
During the Middle Ages and the early modern period the cultivation of the chestnut tree became dominant in various mountain regions in Western Europe. Large numbers of giant chestnut trees have been reported throughout the continent that may be considered the living heritage of this period. In this paper we used a systematic inventory of giant chestnut trees in southern Switzerland for reconstructing the eco-cultural niche related to the long-term cultivation and conservation of such remarkable trees. To this purpose we implemented a retrospective logistic modelling approach with the presence of giant chestnuts as response variable compared with 65 environmental and cultural predictors. We performed different logistic regression analyses using untransformed and transformed variables. Out of the 42 models produced, we finally selected two models, on the basis of their parsimony and accuracy. Many of the selected predictors, such as distance from the lake, abundance of small livestock or number of secondary settlements, reveal that former local and regional socio-economic conditions and environmental constraints have considerable explanatory power. The approach allows us to detect several aspects of the targeted eco-cultural niche that may have acted in the distant past to support the development of the traditional fruit chestnut culture, as well as more recently, to preserve the giant chestnut tree population during the disruption phase of this culture. Most results are in line with the historical documentation, while others go beyond the dictates of written history and reveal interesting traits of the past economic and cultural systems.  相似文献   
180.
Two noted specialists on the agricultural economies of the former Soviet Union examine the effects of land reform on agricultural production and the income of rural house-holds in Tajikistan. The authors utilize official government statistics to discern trends of agricultural output at the national level, and the results of three extensive surveys conducted in 2007-2008 (N > 2,000) and one in 2003 (N = 4,000 respondents) by international organizations (United Nations Food and Agriculture Organization, Asian Development Bank, the U.S. Agency for International Development, World Bank) to identify household-level changes. They also review the legislative framework for agrarian reform in the country; examine national-level trends in farm structure and organization, livestock production, farm productivity, and cropping patterns; and analyze shifts in size of land holdings and rural family incomes at the household level. Journal of Economic Literature, Classification Numbers: D130, O130, P320, Q150. 11 figures, 10 tables, 42 references.  相似文献   
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