Markov Models of Inertia and Dynamism on Two Contiguous Ohio Landscapes

This study examined landcover change during 1940–1988 in two contiguous landscapes of approximately 12,400 hectares in central Ohio, USA: an inertial till plain area and a more dynamic moraine area. Agriculture dominated both landscapes throughout, however, the cover of natural vegetation and urban-suburban development increased over time on the moraine while natural vegetation decreased and agriculture increased on the till plain. Markov process models for landcover change were constructed for three 14–17-year time intervals and for the entire forty-eight-year study period. Probabilities of self-replacement for agricultural lands (0.91–0.97) were higher and those for forests (0.54–0.65) lower than those reported for other landscapes. Predictions of landcover percentages for fifty years in the future were made using Markov process models derived from actual cover changes in 1940–1957, 1971–1988, and 1940–1988. All three models produced similar predictions for the inertial till plain area. In contrast, the three models' predictions differed considerably for the moraine area. Only the 1971–1988 transition matrix was sensitive to increases in urbanization and reforestation which began on the moraine in the 1970s. These results indicate that reliance on lengthy study intervals and net rates of change can obscure spatial and temporal patterns of landcover change that are caused by natural and socioeconomic factors operating on shorter time scales.     

For Whom is the Rural Economy Resilient? Initial Effects of Drought in Western Sudan

This discussion piece addresses two recent debates: entitlement theory and the resilience of rural systems. The authors find that in western Sudan entitlement theory provides a specific and useful framework for understanding the nature of the crisis confronting the society. Arguments about the resilience of rural systems, however, need to be more closely examined and will depend on site-specific factors. The rural economy and society of western Sudan were not found to be resilient.     

Planning in the 1990s: An international agenda

This paper, originally presented to the AESOP‐ACSP joint conference in Oxford in 1991, stresses that both in Europe and in the US, there is a major difference for planning in the switch from boom to recession. During the 1990s a major challenge will be to find new ways of public‐private partnership in financing new urban infrastructure at a time when developer contributions — a major innovation of the 1980s — have dried up. This particularly applies to the European high‐speed train system — one critical element of which will run through the East Thames Corridor, one of Britain's major urban developments in the coming years. In the US, planners are likely to remain more locally focused, less internationally concerned, than in a Europe in which national barriers are rapidly eroding.     

Demand in the Spatial Economy: II Homo Stochasticus

Probabilistic preferences and choices and their connections to trip making and to distance-related demand are discussed. They are seen to aid aggregation. Risk aversion in retail shopping behavior and entropy maximizing as rational random behavior are examined. Elasticity of substitution is presented in terms of the covariance matrix. A Markovian phrasing and potential theory allow an analogy with deterministic choice: various applications of potential operators are outlined. Changes in utilities can only be modeled stochastically and some mechanisms are detailed. Price changes are random walked in time and space as a diffusion process. A fairly coherent theory of spatial demand emerges     

X-ray fluorescence analysis of late Roman and Sassanian silver plate

About 200 analyses have been made on late Roman and Sassanian silver objects using energy-dispersive X-ray fluorescence. This has shown that the main feature of the composition of the silver throughout the period and across the geographical area studied was towards high fineness (average silver percentage about 95%). Compositional differences are found between Roman and Sassanian silversmiths' products for the elements copper and lead. Much of the material analysed came from hoards, and using a statistical technique on the analytical data (Discriminant Analysis) broad compositional differences between hoards were found to emerge. The use of different compositions of silver for different joined parts of a single object are discussed.