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This paper describes an implementation of the 3 T robot architecture which has been under development for the last eight y ears. The architecture uses three levels of abstraction and description languages which a r e compatible between levels. The makeup of the architecture helps to coordinate planful activities with real-time behaviors for dealing with dynamic environments. In recent y ears, other architectures have been created with 1 similar attributes but two features distinguish the 3 T a r c hitecture: 1) a variety of useful software tools have been created to help implement this architecture on multiple real robots and 2) this architecture, or parts of it, have been implemented on a variety o f v ery di erent robot systems using di erent processors, operating systems, e ectors and sensor suites.

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While the needs of many individuals with disabilities can be satisfied with power wheelchairs, some members of the disabled community find it difficult or impossible to operate a standard power wheelchair. To accommodate this population, several researchers have used technologies originally developed for mobile robots to create "smart wheelchairs" that reduce the physical, perceptual, and cognitive skills necessary to operate a power wheelchair. We are developing a Smart Wheelchair Component System (SWCS) that can be added to a variety of commercial power wheelchairs with minimal modification. This paper describes the design of a prototype of the SWCS, which has been evaluated on wheelchairs from four different manufacturers.

Various metals and metalloids can be converted by a variety of microorganisms to their volatile methyl derivatives. These bioconversions are important from an environmental perspective because they take place over long time periods and the products have quite different properties (e.g., transportation, toxicological) as compared to the inorganic species from which they are derived. Whereas the biomethylation of arsenic is well established, that of the closely related element antimony is not, and there are no reports of antimony methylation by monoseptic microbial cultures. We report here, for the first time, the formation of trimethylantimony [(CH3)3Sb] by a characterized microorganism, Scopulariopsis brevicaulis, grown aerobically in the presence of inorganic antimony. Volatile antimony evolved into the headspace above the fungal cultures was quantified by remote trapping and analysis by inductively coupled plasma−mass spectrometry (ICP−MS). The existence of biogenic trimethylantimony was established, following exclusion of oxygen from cultures after growth, by remote trapping of volatile compounds and analysis by gas chromatography with compound-specific (mass spectrometry) or element-specific (atomic absorption) detec tion. No other volatile product containing antimony was detected in culture headspace gases.

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