We extend the results concerning periodic boundary value problems from the continuous calculus to time scales. First we use the Schauder fixed point theorem and the concept of lower and upper solutions to prove the existence of the solutions and then we investigate a monotone iterative method which could generate some of them. Since this method does not work on each time scale, a condition cont...

As complex dynamic systems, urban landscapes emerge from the local interactions of socioeconomic and biophysical agents and processes. These complex systems are highly heterogeneous, spatially nested, and hierarchically structured (Wu and David 2002). They are prototypical complex adaptive systems, which are open, nonlinear, and highly unpredictable (Levin 1998, Portugali 2000, Gunderson and Ho...

Article history: Received 15 February 2005 Received in revised form 29 July 2005 Accepted 9 August 2005 The field of ecoinformatics is concerned with gaining a greater understanding of complex ecological systems. Many ecoinformatic tools, including artificial neural networks (ANNs), can shed important insights into the complexities of ecological data through pattern recognition and prediction; ...