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This paper studies motion planning from one zero-velocity state to another for a three-joint robot in a horizontal plane with a passive revolute third joint. Such a robot is small-time locally controllable on an open subset of its zero-velocity section, allowing it to follow any path in this subset arbitrarily closely. However, some paths are "preferred" by the dynamics of the manipulator in that they can be followed at higher speeds. In this paper, the authors describe a computationally efficient trajectory planner that finds fast, collision-free trajectories among obstacles. The planner decouples the problem of planning feasible trajectories in the robot's six-dimensional state space into the computationally simpler problems of planning paths in the three-dimensional configuration space and time scaling the paths according to the manipulator dynamics. This decoupling is made possible by the existence of velocity directions, fixed in the passive link frame, which can be executed at arbitrary speeds. Results of the planner have been implemented on an experimental underactuated manipulator. To the authors' knowledge, it is the first implementation of a collision-free motion-planning algorithm for a manipulator subject to a second-order nonholonomic constraint.

Two-dimensional calculation of a positive streamer in corona discharge was carried out in the point-plane electrodes in N 2 / NO(300 ppm) and N 2 /O 2 (20%)/NO(300 ppm) at atmospheric pressure. Although similar works have been already published, the distinctive features of our work are (i) the long calculation time ($500 ns) compared with other works, and (ii) the introduction of chemical reactions. The excited species with short radiative lifetime such as N 2 ðB 3 Å g Þ and N 2 ðC 3 Å u Þ are included in addition to radicals and metastable species. First, the physical property of a positive corona streamer was clarified before and after the streamer bridging between the point-plane electrodes. Second, chemical reaction processes in the early discharge stage ($500 ns) were examined. Particularly, the radical production process and its efficiency were evaluated. Third, the effect of turning off the applied voltage on positive streamer corona discharge was studied.

The activity of the promoters involved in transcription of the genes (nirS, nirQ and norC) required for anaerobic reduction of nitrite and nitric oxide was investigated in NIR-and NOR-deficient mutants of Pseudomonas aeruginosa. The transcriptional activity of these three promoters was induced by nitrite in a wild-type strain and the activity was low in an nirS mutant. In norCBD and nirQOP mutants, which were expected to accumulate nitric oxide because of a lack of nitric oxide reductase activity, the norC and nirQ promoters showed significantly enhanced activity in promoting transcription relative to the parental strain, even at low nitrite concentrations. These results suggest that the nirQ and norC promoters are regulated by the concentration of endogenous nitric oxide rather than that of nitrite. z