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471.
Blacic described a transition from basal 〈a〉 to prism 〈c〉 dislocation glide systems as temperature increased or strain-rate decreased in sequences of experiments involving deformation of single crystals of quartz. In this paper theoretical aspects of competition between these systems during plastic deformation are discussed. It is concluded that the basal-prism mechanism switch should have important consequences for the development of crystallographic fabrics during plastic deformation of quartzite, and the Taylor-Bishop-Hill analysis is used in an attempt to predict expected fabric transitions.  相似文献   
472.
This paper tracks changes in relative centralisation and relative concentration of poverty for the 25 largest British cities, analysing change for poor and non-poor groups separately, and examining parallel changes in spatial segregation. The paper confirms that poverty is suburbanising, at least in the larger cities, although poverty remains over-represented in inner locations. Suburbanisation is occurring through both the reduction in low income populations in inner locations and the growth non-poor groups in these places, consistent with a process of displacement. Relative centralisation of poverty has fallen more stronglythan relative concentration of poverty, as the outward shift of poorer groups leaves them still living in denser neighbourhoods on average. The paper also shows that spatial segregation (unevenness) declined at the same time although it remains to be seen whether this indicates a long-term shift to less segregated urban forms or a transitional outcome before new forms of segregation emerge around suburban poverty concentrations.  相似文献   
473.
Effective national and regional policy guidance on climate change adaptation relies on robust scientific evidence. This two-part series of papers develops and implements a novel scenario-neutral framework enabling an assessment of the vulnerability of flood flows in British catchments to climatic change, to underpin the development of guidance for the flood management community. In this first part, the sensitivity of the 20-year return period flood peak (RP20) to changes in precipitation (P), temperature (T) and potential evapotranspiration (PE) is systematically assessed for 154 catchments. A sensitivity domain of 4,200 scenarios is applied combining 525 and 8 sets of P and T/PE mean monthly changes, respectively, with seasonality incorporated using a single-phase harmonic function. Using the change factor method, the percentage change in RP20 associated with each scenario of the sensitivity domain is calculated, giving flood response surfaces for each catchment. Using a clustering procedure on the response surfaces, the 154 catchments are divided into nine groups: flood sensitivity types. These sensitivity types show that some catchments are (very) sensitive to changes in P but others buffer the response, while the location of catchments of the same type does not show any strong geographical pattern. These results reflect the range of hydrological processes found in Britain, and demonstrate the potential importance of catchment properties (physical and climatic) in the propagation of change in climate to change in floods, and so in characterising the sensitivity types (covered in the companion paper).  相似文献   
474.
This article examines the effect of the Kyoto Protocol's Clean Development Mechanism (CDM) on the international transfer of wind power technologies. The analysis is conducted using patent data from over 100 countries during the period 1988–2008. It is found that transfers from Annex I countries to non-Annex I countries are significantly affected by the contemporaneous establishment of projects under the CDM. However, when taking into account the cumulative effect of CDM projects, the effect is negative. Finally, the effect of domestic absorptive capacity in the host country is positive and significant. Because involvement with the CDM may increase the latter, this is an important area for further research.  相似文献   
475.
<正>In the last decade there has been a considerable effort to better understand the joint evolution of mafic and ultramafic magmatic systems and their deep mantle roots,through integrated petrological and thermo-barometric studies.Magma generation is regarded as the result of complex processes including melting,creation of channels for melt transfer,and interaction with the wall-rocks.Complexities in magmatic systems involve metasomatism and the creation of metasomatic fronts,branching and splitting of magma volumes during their evolution,and vat-  相似文献   
476.
新疆伊犁吐拉苏地区的线性构造及控矿特征   总被引:4,自引:0,他引:4  
肖龙  HaywardNick 《地球科学》2003,28(2):191-195
采用多种数值图像进行线性构造解译,其中DEM和NOAA主要用于区域尺度,TM用于勘探区尺度,地面磁法数据用于靶区范围的解译分析。研究认为该区线性构造与金矿床的空间分布关系密切,表现为:(1)区域尺度的一级控矿构造为NEE、NE和NW向构造的交汇部位;吐拉苏地区的一级控矿构造为WNW和NNW及NE方向构造的交汇部位;(2)吐拉苏地区的次级控矿构造为NNE和环形构造的交汇部位;(3)靶区的一级控矿构造为NE、SN和环形构造。线性构造异常分析结果显示,当线性构造的优益度大于40时,有较大的成矿可能性。  相似文献   
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