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Limited natural resources and landfill space and increasing amounts of ash produced from incineration of bio fuel and solid wastes have created a demand for useful applications of ash of which road construction is one. Here the environmental impact of a fly ash layer in a reconstructed road was evaluated by studying the soil solution chemistry in the ash layer, at two depths in the soil below and at two depths in the ditch using a centrifugation drainage technique. The road was situated about 20 km west of Sollefteå, (63˚ 16� 33�N, 17˚12�52�E) in the middle of Sweden. Two years after the application of the ash the concentrations of zinc were increasing in the ash layer solutions while concentrations of cadmium were stabilising. Below the ash layer in the road an initial increase of the pH was observed and the concentrations of potassium, sulphate and cadmium showed an increase while copper and mercury showed decreasing concentrations in the road and the ditch soil solutions. The concentrations in the ditch soil solutions were generally much lower compared to the road. Concentrations of calcium in the ash layer solutions indicated that hardening had taken place.

To explore brain areas involved in basic numerical computation, functional magnetic imaging (fMRI) scanning was performed on college students during performance of three tasks; simple arithmetic, numerical magnitude judgment, and a perceptual-motor control task. For the arithmetic relative to the other tasks, results for all eight subjects revealed bilateral activation in Brodmann's area 44, in dorsolateral prefrontal cortex (areas 9 and 10), in inferior and superior parietal areas, and in lingual and fusiform gyri. Activation was stronger on the left for all subjects, but only at Brodmann's area 44 and the parietal cortices. No activation was observed in the arithmetic task in several other areas previously implicated for arithmetic, including the angular and supramarginal gyri and the basal ganglia. In fact, angular and supramarginal gyri were significantly deactivated by the verification task relative to both the magnitude judgment and control tasks for every subject. Areas activated by the magnitude task relative to the control were more variable, but in five subjects included bilateral inferior parietal cortex. These results confirm some existing hypotheses regarding the neural basis of numerical processes, invite revision of others, and suggest productive lines for future investigation. Copyright (C) 1999.