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The purpose of this paper is to demonstrate cross‐Channel exchange of calcareous sandstone‐type whetstones derived from the Weald (Sussex, UK) in the Roman period. The presence of this particular type of whetstone at several Roman sites on the Continent – more specifically, in Belgium, France and the Netherlands – is reported for the first time. The morphology, geological provenance, petrographic characteristics and distribution patterns are discussed, based on a comparative analysis with archaeological and geological reference material. The geological analysis identifies a common geological source for the Continental finds: the very fine‐grained, thin‐bedded, flagstone‐like calcareous sandstone beds of the Lower Cretaceous Wealden Clay Formation. These sandstones were, most probably, extracted in the north‐western part of the Weald area. The distribution pattern of the archaeological material implies the importance of personal mobility, with potential military affinities.  相似文献   
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Salt-accumulating renders are usually applied in several layers with different specific properties of moisture transport. An extensive experimental programme was carried out to establish a relationship between those properties of individual layers and the performance of combined systems on a salt-laden substrate. Each of the 20 renders was characterized separately in absorption and drying tests, vacuum saturation tests, dry cup tests, mercury intrusion porosimetry, and ultrasound wave velocity measurements. Each of the 12 combined render systems was applied on a brick, which was then saturated with a concentrated NaCl solution by free capillary uptake. Subsequently the assembly was closed at the bottom and subjected to an accelerated drying test (50° C and 15% relative humidity). Moisture and salt profiles over the depth were taken regularly during 1 month. The results reveal very different degrees of effectiveness and levels of risk for the substrate, which are related to the moisture transport properties.  相似文献   
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In this article it is argued that conventional agro-ecological and organizational concepts used in pastoral development are strongly biased towards the formulation and enforcement of norms. This leads development experts to attempts to control pastoralists and their herds. The policies and development interventions based on these assumptions have been largely unsuccessful. As a consequence attention for dryland areas and pastoral development has declined among researchers and development agencies. An important reason for this failure is the fundamental misfit between these normative concepts and the reality of dryland ecosystems and pastoral society. In order to show this, an alternative view on rangeland ecology and pastoral society is presented, supported by a case study of Fulbe pastoral society in dryland Central Mali. The authors argue that approaches to pastoral development must be revised in the direction of the dynamics inherent in the pastoral way of life.  相似文献   
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