29 research outputs found

    The Settlement and Drainage of the Wentlooge Level, Gwent: Excavation and Survey at Rumney Great Wharf 1992

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    Reproduced with the permission of the publisher and JSTOR. Journal home page http://www.romansociety.org/frame.htmIntroduction: The Wentlooge Level in SE Wales represents an extensive area of some 35 km' of alluvium reclaimed from estuarine saltmarsh from the Romano-British period onwards (FIGS I-2).1 As was noted by Allen,' the landscape is characterised at its southern and northern extremities by a pattern of small irregular fields, often fossilizing the meanderings of natural drainage channels (FIG. 2). This arrangement is typical of many of the reclaimed alluvial wetlands that fringe the Severn Estuary.' The remainder of the Wentlooge Level is distinguished by a very different landscape, comprising regularly planned blocks of long, narrow, and generally straight-sided fields, quite unique among the wetlands of the Severn Estuary.4 At Rumney Great Wharf, north east of Cardiff, part of the latter field-system can be seen cut into a clay-peat shelf in the intertidal zone (see below), thus indicating a major episode of coastal retreat and the repositioning of the sea-wall across it;s similar evidence from the intertidal zone can be recognised as far to the north-east as Peterstone Gout.6 An extensive spread of Romano-British pottery and primitive iron-making slag was associated locally with this field-system in the intertidal zone at Rumney Great Wharf, while survey of the adjacent mud cliff revealed at least one ditch, sealed by a buried palaeosol, which yielded stratified Roman material. Further erosion of the mud cliff revealed more ditches with Romano- British material, as well as other indications of settlement, and prompted a programme of survey and excavation grant-aided by Cadw and the National Museum of Wales in the spring of 1992

    The Metapopulation Dynamics of an Infectious Disease: Tuberculosis in Possums

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    An SEI metapopulation model is developed for the spread of an infectious agent by migration. The model portrays two age classes on a number of patches connected by migration routes which are used as host animals mature. A feature of this model is that the basic reproduction ratio may be computed directly, using a scheme that separates topography, demography, and epidemiology. We also provide formulas for individual patch basic reproduction numbers and discuss their connection with the basic reproduction ratio for the system. The model is applied to the problem of spatial spread of bovine tuberculosis in a possum population. The temporal dynamics of infection are investigated for some generic networks of migration links, and the basic reproduction ratio is computed—its value is not greatly different from that for a homogeneous model. Three scenarios are considered for the control of bovine tuberculosis in possums where the spatial aspect is shown to be crucial for the design of disease management operation

    The metapopulation dynamics of an infectious disease: a case study of tuberculosis in possums

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    An SEI metapopulation model is developed for the spread of an infectious agent by migration. The model portrays two age classes on a number of patches connected by migration routes which are used as host animals mature. A feature of this model is that the basic reproduction ratio may be computed directly, using a scheme that separates topography, demography, and epidemiology. We also provide formulas for individual patch basic reproduction numbers and discuss their connection with the basic reproduction ratio for the system. The model is applied to the problem of spatial spread of bovine tuberculosis in a possum population. The temporal dynamics of infection are investigated for some generic networks of migration links, and the basic reproduction ratio is computed—its value is not greatly different from that for a homogeneous model. Three scenarios are considered for the control of bovine tuberculosis in possums where the spatial aspect is shown to be crucial for the design of disease management operations
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