Abstract:The modern education community agrees that deep and effective learning is best promoted by situating learning in authentic activity. Many in the education community have put in place constructivist classroom practices that put students into situations where they must make hypotheses, collect data, and determine which data to use in the process of solving a problem or participating in some kind of realistic analysis or investigation. Research in case-based reasoning (CBR), which provides a plausible model of learning from problem solving situations, makes suggestions about education that are consistent with these educational theories and methodologies and which can provide added concreteness and detail. In this paper, we show how CBR's suggestions can enhance problem-based learning (PBL), which is already a well-worked-out and successful approach to education. The computational accounts CBR provides of reasoning activities, especially of knowledge access, access to old experiences (cases), and use of old experiences in reasoning, suggest guidelines about materials that should be made available as resources, the kinds of reflection that will promote transfer, qualities of good problems, qualities of the environment in which problems are solved (e.g., affordances for feedback), and sequencing a curriculum. The two approaches complement each other well, and together, we believe they provide a powerful foundation for educational practice in the constructivist tradition, one that at once combines lessons learned from classroom practice with sound cognitive theory.

In this paper, we present the Firefighter Communication System --a system designed to enhance and improve firefighter communication during a crisis situation such as a structural fire. The system we present is a half-duplex communication system with an audio horizon for officers and a full-duplex system for standard firefighters. We also address the design for the company commander who simultaneously participates in both systems. These initial designs are the result of ethnographic-style investigations into firefighting practice combined with iterative design.

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An alternative inflationary model is proposed predicated upon a consideration of the form of the uncertainty principle in a curved background spacetime. An argument is presented suggesting a possible curvature dependence in the correct commutator relations for a quantum field in a classical background which cannot be deduced by simply extrapolation from the flat spacetime theory. To assess the possible consequences of this dependence, we apply the idea to a scalar field in a closed FriedmannRobertsonWalker background, using a simple model for the curvature dependence (along the way, a previous result obtained by Bunch (1980) for the adiabatically expanded wave function is corrected). The result is a timedependent cosmological constant, producing a vast amount of inflation that is independent of the mass of the matter field or its effective potential. Furthermore, it is seen that the field modes are initially zero for all wavelengths and come into being as the universe evolves. In this sense, the universe creates its contents out of its own expansion. At the end of the process, the matter field is far from equilibrium and essentially reproduces the initial conditions for the New Inflationary Model.