The Urban Crisis And The Federal Government\u27s Retreat: Catalyzing Public Policy Choices To Save Our Cities

Sections of our cities have been abandoned to a host of poverty-related social ills whose causes have as much to do with the state of the national and regional economies, structural changes in the job market, and political decision-making as they have to do with individual life-histories and personal misfortune. Bleak outcomes are not inevitable and can be reversed by understanding why faulty policy options were adopted and what it will take to formulate new policies. This essay argues for the need of proactive solutions like in combating our urban povery problem by using, (1) a Marshall Plan for cities, (2) using politics as a mechanism for change, and (3) using nonprofit social agencies and other community service organizations to help move the political agenda

Linear-Time Poisson-Disk Patterns

We present an algorithm for generating Poisson-disc patterns taking O(N) time to generate $N$ points. The method is based on a grid of regions which can contain no more than one point in the final pattern, and uses an explicit model of point arrival times under a uniform Poisson process.Comment: 4 pages, 2 figure

Using a fuzzy inference system to control a pumped storage hydro plant

The paper discusses the development of a fuzzy inference system (FIS) based governor control for a pumped storage hydroelectric plant. The First Hydro Company's plant at Dinorwig in North Wales is the largest of its kind in Europe and is mainly used for frequency control of the UK electrical grid. In previous investigations, a detailed model of the plant was developed using MATLAB(R)/SIMULINK(R) and this is now being used to compare FIS governor operation with the proportional-integral-derivative (PID) controller currently used. The paper describes the development of an FIS governor, and shows that its response to a step increase in load is superior to the PID under certain conditions of load. The paper proceeds to discuss the implications of these results in view of the possible practical application of an FIS governor at the Dinorwig plant

The Stability of the orbits of Earth-mass planets in and near the habitable zones of known exoplanetary systems

We have shown that Earth-mass planets could survive in variously restricted regions of the habitable zones (HZs) of most of a sample of nine of the 93 main-sequence exoplanetary systems confirmed by May 2003. In a preliminary extrapolation of our results to the other systems, we estimate that roughly a third of the 93 systems might be able to have Earth-mass planets in stable, confined orbits somewhere in their HZs. Clearly, these systems should be high on the target list for exploration for terrestrial planets. We have reached this conclusion by launching putative Earth-mass planets in various orbits and following their fate with a mixed-variable symplectic integrator

The on-farm impact of alternative grazing management options to improve sustainability in western Chinese grasslands

Chinese grasslands are suffering considerable pressures from human and livestock populations. It has been estimated that 90% of Chinese grasslands are suffering from light to heavy levels of degradation. Allied to this is the low household income of herders and farmers dependant upon livestock products for their livelihood. Although a range of reasons have been proposed for the high levels of grassland degradation, principal among these are the high stocking rates adopted by farmers. This not only results in high utilisation rates of the pasture biomass, leading to bare areas and soil erosion, but individual animal productivity rates also decline. This paper presents the results of a modelling study of a grassland system in Gansu Province and Inner Mongolia Autonomous Region in northern China. This shows that reducing stocking rates leads to not only an increase in livestock productivity, but whole-farm returns are also increased. From a sustainability perspective, the greater pasture biomass remaining on the grassland also reduces the incidence of soil erosion in the areas.sustainable grazing, bioeconomic model, China, Farm Management, Livestock Production/Industries, Resource /Energy Economics and Policy,