Resistance to sulfonylurea herbicides, including bensulfuron-methyl, pyrazosulfuron-ethyl, imazosulfuron and ethoxysulfuron, was discovered in naturally occurring populations of Lindernia micrantha D. Don in rice ®elds that had been treated with sulfonylurea-based herbicides for 3±7 consecutive years. The resistant biotype was approximately 80»300 times more resistant than the susceptible one to the above four sulfonylurea herbicides. This is the second con®rmed occurrence of herbicide resistance resulting from the use of sulfonylurea herbicides in Japan. Several herbicides with dierent modes of action, including pretilachlor, cafenstrole, bifenox, naproanilide, thiobencarb + simetryn + MCPB, MCPA-thioethyl + simetryn and cyhalofop-butyl + bentazone, eectively controlled the resistant biotype in pot trials.

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An isosurface c an be eciently generated by visiting adjacent intersected c ells in order, as if the isosurface were p r opagating itself. We previously proposed an extrema graph method, which generates a graph connecting extremum points. The isosurface p r opagation starts from some of the intersected c ells that are found both by visiting the cells through which arcs of the graph pass and by visiting the cells on the boundary of a volume.In this paper, we propose an ecient method o f searching for cells intersected by an isosurface. This method generates a volumetric skeleton consisting of cells, like an extrema graph, by applying a thinning algorithm used in the image recognition area. Since i t preserves the topological features of the volume and the connectivity of the extremum points, it necessarily intersects every isosurface. The method is more ecient than the extrema graph method, since i t d o es not require that cells on the boundary be visited.

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Mechanisms of initiation of phase III contractions in the jejunum during the digestive state are not well understood. To test whether phase III can be induced by a local injection of various agents in a jejunal segment, a polyethylene tube was chronically placed in a branch of the jejunal artery, and force transducers were chronically placed in the upper jejunum. Local injection of atropine, hexamethonium and xylocaine induced caudal-migrating phase III in the injected segment only in the digestive state, and simultaneous intra-arterial infusions of L-arginine, an NK-1 antagonist, or 5-hydroxytryptamine (5-HT) 1P and 3 antagonists inhibited the induced phase III. Intravenous atropine and hexamethonium also inhibited xylocaine-induced phase III contractions. Atropine and hexamethonium-induced phase III were brought about by inhibition of neural transmission at nicotinic receptors in the inhibitory pathway to NO neurones. NK-1, 5-HT1P and 5-HT3 receptors are present in the excitatory but not the inhibitory pathway to NO neurones. Xylocaine appears to stop neuronal transmission from mechanoreceptors to NO neurones. Thus, the initiation of spontaneous occurrence of phase III in the digestive jejunum is likely to be brought about by transient cessation of postprandial contractions in a segment of the jejunum.