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

Human-Robot Interaction with Drones and Drone Swarms in Law Enforcement Clearing Operations

Police officers often must work alone in clearing operations, a procedure that involves surveying a building for threats and appropriately responding. A partnership between drone swarms and officers has potential to increase the safety of officers and civilians during these high-stress operations and reduce the risk of harm from hostile persons. This two part study examines aspects of trust, situational awareness, mental demand, performance, and human-robot interaction during law enforcement building clearing operations using either a single drone or a drone swarm. Results indicate that single drone use can increase time for operation, but accuracy and safety of clearing is enhanced. Single drone use saw increased situational awareness, a decrease in number of targets missed, and a moderate level of trust. For drone swarms, results indicate significant differences in mental workload from swarm data feeds compared to single drone feeds but no substantial difference in accuracy of finding targets. </jats:p

Nutrient Transient Storage by the Invertebrate Assemblage in Streams with Contrasting Nutrient Loads

Ecological processes occurring at the water-sediment interface have major effects on the dynamics of nutrients in low order streams. Nutrients are removed from the water column by microbial biofilms that, in turn, are consumed by the invertebrate assemblage. In this study we estimated the amount of elements (C, N, P) that flow through the invertebrate assemblages of several streams throughout Europe, all of them impacted by wastewater treatment plants. Our approach coupled secondary production estimates with elemental measures of C, N, P content of invertebrate taxa. This research is part of the EU-project STREAMESJRC.H.5 - Rural, water and ecosystem resource