Do students' perceptions of school smoking policies influence where students smoke?
Clearly perceived rules about smoking encourage students not to smoke on school grounds; however, perceptions of rules, along with strong enforcement, may displace behavior off of school grounds. Non-smoking policies should be part of a comprehensive approach, that supports cessation.
These results suggest that the effect of nitrate is compatible with a rapid and transient increase in the activity of glutamine synthetase and urease during the first hour after the onset of treatments. Nevertheless, a possible effect of nitrate reducing ammonium accumulation through the activation of alternative metabolic pathways different from that involving glutamine synthetase cannot be ruled out. Finally, nitrate effects on amino acid concentration indicate that, whereas ammonium assimilation takes place principally in the root, urea and nitrate assimilation occurred in the shoot, under the conditions of the experiment.