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Systematic collecting from fluvial late Pleistocene deposits from the Darling Downs, southeast Queensland, Australia, has led to the recovery of the first fossil frogs from the region, ail from the Myobatrachidae, a family of ground dwelling and burrowing frogs. The most common species recovered, Limnodynastes tasmaniensis, is extant on the Darling Downs. The fossil taxa include species whose extant populations inhabit arid zones(Limnodynastes sp. cf. L. spenceri), montane forests (Kyarranus spp.), and open woodlands (Neobatrachus sudelli), and indicate the existence of a mosaic of habitats during the Pleistocene. The absence of the Hylidae (tree frogs), a family common throughout the Darling Downs today, may be explained by a taphonomic bias that favours non-arboreal forms. Alternatively, hylids may have been rare or absent on the Darling Downs during the Pleistocene.  相似文献   
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Substantial changes to the built environment, urbanisation patterns, and societal norms have contributed to limiting children's opportunities for being independently mobile. Several linear causal pathway models have been developed to understand the influences on children's independent mobility; however feedback loops between and within the various levels of influence cannot be modelled using such an approach. The purpose of this paper is to refine the interrelationships of factors related to children's independent mobility, taking into account earlier models, broader contextual factors, recent children's geographies literature, and feedback loops. Systems model components were informed by attributes known to influence children's independent mobility, related qualitative findings, and the development of a framework that could lend itself to multilevel modelling approaches. This systems model may provide a useful structure for identifying how best to develop and monitor interventions to halt the declining rates of children's independent mobility.  相似文献   
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This short briefing paper addresses the next stage in the evolution of regional development policy. It is clear that the cluster idea has held sway in this field for some 20 years. By now, practitioners and academics are widely sceptical of policy capabilities to create let alone build clusters. Recessionary times make this more difficult. Moreover, where some recent success can be seen, it is associated with command economies such as China where normal market and democratic barriers to large public investments in such measures are absent. Nevertheless, clusters exist in many places and there is evidence, displayed in this paper, that in some regions they have mutated into multi-cluster platforms. Now, as regions seek to rebalance, platform policies are evolving and being implemented. This paper shows how this is in part a response to “Grand Challenges” and the emergence of “challenge-driven” innovation.  相似文献   
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