Invariant elliptic curves as attractors in the projective plane

Let f be a rational self-map of P^2 which leaves invariant an elliptic curve C with strictly negative transverse Lyapunov exponent. We show that C is an attractor, i.e. it possesses a dense orbit and its basin is of strictly positive measure

The STREAMES project: linking heuristic and empirical knowledge into an expert system to assess stream managers

Contribution presented at iEMSs 2002 Integrated Assessment and Decision Support Conference held in Lugano, Switzerland, on 24-27 June 2002. More details at http://www.iemss.org/iemss2002/.The increase in stream nutrient loads from anthropogenic sources has become a serious problem, especially in developed regions. Humans affect streams by modifying the landscape in ways that increase the transport of nutrients to surface waters, by directly dumping urban or industrial sewage into the stream, or by modifying streams in ways that reduce their ability to respond to increased nutrient loads. In Mediterranean regions these problems are compounded by the scarcity of water. The decision-making processes involved in water quality management require extensive human expertise or extensive computation with large data sets. In this sense, the STREAMES project aims to develop a knowledge-based environmental decision support system (EDSS) to support and advice water managers in the management of human-altered streams. This EDSS will integrate an Expert System (ES), concretely a rule-based reasoning system (RBS), with a Geographical Information System to address spatial information for the appropriate stream management actions, and a numerical model to estimate point and non-point nutrient sources from middle size catchments. The RBS will be developed by integrating heuristic knowledge from experts in surface water management, as well as empirical knowledge from stream scientists, based both on previous studies and on data directly acquired from experimental sampling. This paper will present the objectives of the STREAMES project with emphasis in the knowledge acquisition and development of the RBS.Peer reviewe

Integrating point and diffuse pollution in an Environmental Decision Support System for stream management at reach scale

24 PáginasPeer reviewe

Nutrient transient and storage by the invertebrate assemblage in streams with contrasting nutrient loads

Peer reviewe