Run-Time Selection of Coordination Mechanisms in Multi-Agent Systems

This paper presents a framework that enables autonomous agents to dynamically select the mechanism they employ in order to coordinate their inter-related activities. Adopting this framework means coordination mechanisms move from the realm of being imposed upon the system at design time, to something that the agents select at run-time in order to fit their prevailing circumstances and their current coordination needs. Empirical analysis is used to evaluate the effect of various design alternatives for the agent's decision making mechanisms and for the coordination mechanisms themselves

A Brazilian anuran (Hylodes magalhaesi: Leptodactylidae) infected by Batrachochytrium dendrobatidis: a conservation concern

Several studies have associated the chytrid fungus Batrachochytrium dendrobatidis with anuran population declines worldwide. To date, the fungus has been found in Africa, the Americas, Australia, and Europe. However, it has never been reported to occur in the Atlantic forest or Brazil. Based on morphological, histological, and molecular data, we encountered evidence of B. dendrobatidis infection in a high-altitude stream-dwelling Brazilian anuran species, Hylodes magalhaesi (Leptodactylidae). One population (Municipality of Camanducaia, State of Minas Gerais) was surveyed from 2001 to 2005. Tadpoles lacking teeth were observed and collected in 2004. Histological and molecular analyses identified infection by B. dendrobatidis. Although infected tadpoles seem nowadays to co-exist with the disease, our results are alarming due to the highly endangered situation of the Brazilian Atlantic forest and its fauna. Effects of the chytrid infection on the studied population are still unknown. Further investigations are needed to provide information on its distribution in relation to other populations of H. magalhaesi

Análisis de la transición de la física clásica a la relativista desde la perspectiva del "cambio conceptual"

Interviews about special relativity are realized with students of a Modern Physics course. The results of the interviews' analysis suggest that conceptual change doesn't mean a substitution of classic physics conceptions by the relativistic ones but that there is an interactive coexistence of both

Population Density and Home Range Estimates of Black Rat (Rattus rattus) Populations in Southwestern Puerto Rico

Black rats are among the world’s most invasive rodent species and are responsible for considerable agricultural losses and risks to human health through zoonotic disease. In Puerto Rico, rats may also compete with the primary rabies reservoir (the small Indian mongoose) for baits during oral rabies vaccination (ORV) programs. We evaluated black rat population density and home range size on the Cabo Rojo National Wildlife Refuge, southwestern Puerto Rico. We fitted 10 rats with VHF transmitters and tracked them using radio telemetry for approximately 4 weeks. We entered locations into ArcGIS and obtained minimum convex polygon (MCP) home range estimates. We established two plots of 55 snap traps and performed removal for 5 consecutive days during January and July, to correspond roughly with wet and dry seasons for this region. To calculate abundance, we entered snap trap data using a removal model approach in Program MARK. We calculated the effective trapping area by creating a buffer around the trapping area based on the square root of mean home range estimate. We divided the abundance calculated in MARK by the effective trapping area to calculate the estimated population density. Mean MCP home range estimate was 0.28 ha (SE: 0.05, range: 0.07-0.50 ha). Population density estimates were 114.7 (SE: 201.80) and 19.3 (SE: 6.85) per ha for January and July, respectively. To reduce the potential for rat consumption of ORV baits, wildlife managers should consider conducting ORV activities in Puerto Rico during periods of lower rat abundance or density