Patterns of metropolitan development : what have we learned?

Much of our knowledge about metropolitan development is still imperfect, but in the past 35 years a great deal of theoretical and empirical work has been carried out in cities and metropolitan areas in both industrial and developing countries with market-oriented economies. This work has produced empirical findings with remarkably strong regularities across countries and cities. Moreover, many of these empirical regularities are quite consistent with urban location theory and suggest the broad applicability of our basic theory to market-based cities. These regularities offer insights about development and growth pressures in many cities and indicate the directions future development is likely to take. The development pattern of cities in industrial and developing countries with market-based economies exhibit similar patterns of decentralization of both population and employment, with the largest metropolitan areas converging to similarly decentralized structures with multiple subcenters, highly decentralized manufacturing employment, and the central business districts'emerging specialization in service employment. Cities in developing countries typically have higher population densities than those in industrial countries, but the differences have been narrowing over time in the largest metropolitan areas. Decentralization of population and employment increases reliance on road-based transport for both passengers and freight. Industrial countries have experienced decreases in transit use as auto ownership levels have risen. Many developing countries show early signs of a similar pattern, although their transit ridership levels are still high and their transit systems often offer a rich mix of options in terms of vehicle size and level of service. Land markets are strong determinants of decentralization. Cities without land markets exhibit quite different development patterns from cities with even poorly functioning land markets. In market-based cities, land rents are closely related to development densities, although empirical work on land rents and values is relatively rare, for lack of data. Demand patterns in urban housing markets are similar across cities in developing and industrial countries for supply-side impediments vary widely -resulting in a wide range of ratios of housing prices to income. Similarly, the efficiency with which public infrastructure is provided varies widely across cities and across sectors within cities. In the coming decades global urbanization will increase, mostly in low-income countries (which in 1995 contained nearly 60 percent of the world's people). Many of those low-income countries already have large metropolitan areas, whose populations will continue to grow.Banks&Banking Reform,Urban Housing and Land Settlements,Urban Services to the Poor,Municipal Financial Management,National Urban Development Policies&Strategies,Banks&Banking Reform,Urban Housing and Land Settlements,National Urban Development Policies&Strategies,Urban Services to the Poor,Municipal Financial Management

Contributions to the mixed-alkali effect in molecular dynamics simulations of alkali silicate glasses

The mixed-alkali effect on the cation dynamics in silicate glasses is analyzed via molecular dynamics simulations. Observations suggest a description of the dynamics in terms of stable sites mostly specific to one ionic species. As main contributions to the mixed--alkali slowdown longer residence times and an increased probability of correlated backjumps are identified. The slowdown is related to the limited accessibility of foreign sites. The mismatch experienced in a foreign site is stronger and more retarding for the larger ions, the smaller ions can be temporarily accommodated. Also correlations between unlike as well as like cations are demonstrated that support cooperative behavior.Comment: 10 pages, 12 figures, 1 table, revtex4, submitted to Phys. Rev.

A WILLINGNESS TO PLAY: ANALYSIS OF WATER RESOURCES DEVELOPMENT

Economic analysis shows that the Central Arizona Project will be a poor investment from the point of view of individual farmers. Yet farmers support the Project. In this study of the economics and politics of the CAP, farmers are questioned as to their information, perceptions and motivations. Farmers are willing to play – not necessarily to pay.Resource /Energy Economics and Policy,