This report of the discovery of low walls running across the slopes east of the Dead Sea presents an important landmark in the history of farming, for these were terrace walls put in place to conserve soil and control water around 6000 cal BC. The authors point to some of the implications of what they see as early landscape modification at the scale of a small community or household.

In Näätänen's model of early attention, the role of arousal in influencing the permanent feature detection system (indexed by mismatch negativity [MMN]) and the temporary feature-detection system (indexed by processing negativity [PN]) is unclear. To address this question, we investigated the effects of the anesthetic gas nitrous oxide (N2O) on the MMN and PN. Ten subjects performed a dichotic listening task in which discrimination difficulty and breathing mixture (air or 25% N2O) were manipulated factorially. MMN, PN, N1 and P300 at Fz, Cz, and Pz, as well as reaction time (RT), were measured. N2O had no effect on the PN, but decreased MMN amplitude. As expected, N2O decreased the amplitude of the N1 and P300 and increased the latency of the P300 and RT. The dissociation of MMN and PN by N2O suggests that this agent decreases the ability to detect automatic stimulus change without affecting voluntary selective attention. We interpret these results as indicating that arousal has multidimensional effects on early attentional mechanisms. These dimensions can be differentiated chemically by neurotransmitters in the reticular formation of the brain.

The luminescent properties of AlGaN epitaxial layers with AlN mole fractions up to 30% and various types of AlGaN/GaN-based heterostructures have been studied. The structures were grown on 6H-SiC substrates by MOCVD. The structures' cathodoluminescence and electroluminescence were measured. A “blue” shift of the edge luminescent peak position for AlGaN alloys was measured to be a non-linear function on the AlN mole fraction. For p-AlGaN/n-GaN double heterostructures (DH), the edge peak position was detected at 365 nm (300K). For a p-Al0.05Ga0.95N/n-Al0.03Ga0.97N heterostructure, the electroluminescent edge peak was observed at 355 nm (300K). The effects of temperature and forward current on the edge electroluminescence of theAlGaN/GaN DH's were investigated.