1. Stimulation of the sensorimotor cortex was found to excite and/or inhibit nociceptive spinothalamic tract cells. Thirteen wide dynamic range cells were inhibited by cortical stimulation, 6 were excited and 14 were both excited and inhibited. Four of six high-threshold cells were excited and one was inhibited. 2. Intermediate (200 ms) or long (2 s) duration conditioning trains were effective in reducing responses of spinothalamic cells evoked by noxious mechanical or thermal stimuli and by A- and C-fiber volleys in the sural nerve. Preferential inhibition of low-threshold responses with little or no effect on high-threshold discharges was observed in some cases. 3. Inhibitory actions were obtained primarily from stimulation of the SI sensory cortex and area 5, while excitation or excitation followed by inhibition was the dominant effect from motor cortex (area 4). Spinothalamic cells were also excited by stimulation of the medullary pyramid. 4. In eight animals extensive mapping of the sensorimotor cortex showed that for a given cell, stimulation of the sensory cortex produced inhibition while stimulation of motor cortex resulted in excitation. 5. The average latency of inhibition from sensory cortex was 29.8 +/- 10 ms, while the average latency of excitation from motor cortex was significantly shorter, 13.5 +/- 9 ms. The shortest latencies for excitation from pyramidal stimulation in the cases evaluated ranged from 2 to 9 ms. 6. Spinal cord lesions were made in five animals to determine the descending pathway(s) mediating corticofugal effects. Cortical and pyramidal effects were eliminated or considerably reduced by lesions involving the dorsal part of the lateral funiculus. This observation combined with latency data suggest that the corticospinal tract may be involved in the mediation of cortical excitation, while both pyramidal and extrapyramidal pathways are likely to be involved in cortical inhibition.

The USA and USSR jointly constructed a special test section of 915-mm diameter Reinforced Plastic Mortar (RPM) fiberglass pipe in June 1979 near Riga, Latvia. This experiment was part of the working agreement of the US-USSR team “Investigations of Effectiveness of Plastic Pipe in Drainage and Irrigation.” Measurements were made of pipe deflections, soil properties, and in-place densities. Six different embedment conditions were used. The pipe deflections were measured during each state of construction and over a 4-year period. Data of particular interest is the increase in the vertical diameters caused during soil compaction at the sides of the pipe and the frequent deflection measurements in the few weeks following the final placement of the 3 m of backfill over the pipe. The ratio of the vertical deflection after 4 years to the vertical deflection on the day the backfilling was completed ranges from 1.6 to 1.7 for the dumped side support, 4.5 for a side support with a moderate degree of compaction, and 2.2 to 2.9 for the side support placed to a high degree of compaction.

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