Summary Lead (Pb) from the traffic accumulates in roadside soils, which are usually vegetated to control erosion. Plants release soluble organic substances that bind Pb. Root macropores also create preferential pathways through which water can flow. Both these processes may enhance Pb mobility. We used large lysimeters to investigate the transport of Pb in a contaminated (445 mg Pb kg −1 ) soil under vegetation ( Phacelia tanacetifolia ). Despite the high soil pH (7.2), Pb leached into the drainage water during the 5‐month experiment. The fast response of the system to intense rainfall events indicated the presence of preferential flow. By comparing Pb concentrations in filtered and unfiltered leachates, we found that Pb was leaching primarily on suspended material. An increase in Pb concentration in the leachate at the end of the experiment indicated the remobilization of Pb, possibly by decaying vegetation. We parameterized the dual‐porosity MACRO model using the experimental results. The simple parameterization of MACRO used to simulate the Pb concentrations in the drainage water produced an overall model efficiency of 0.81: MACRO simulated the Pb concentrations well, but it failed to predict the observed increase of Pb in the leachate at the end of the experiment. The model gave the best prediction of Pb concentrations with a small partition coefficient ( k d = 150 cm 3 g −1 ). Long‐term simulations of Pb mobility showed that for our specific conditions preferential flow was the main process determining the fate of Pb.
There is little information concerning the long term outcome of patients with gastro-oesophageal reflux disease (GORD). Thus 109 patients with reflux symptoms (33 with erosive oesophagitis) with a diagnosis of GORD after clinical evaluation and oesophageal testing were studied. All patients were treated with a stepwise approach: (a) lifestyle changes were suggested aimed at reducing reflux and antacids and the prokinetic agent domperidone were prescribed; (b) H2 blockers were added after two months when symptoms persisted; (c) anti-reflux surgery was indicated when there was no response to (b). Treatment was adjusted to maintain clinical remission during follow up. Long term treatment need was defined as minor when conservative measures sufficed for proper control, and as major if daily H2 blockers or surgery were required. The results showed that one third of the patients each had initial therapeutic need (a), (b), and (c). Of 103 patients available for follow up at three years and 89 at six years, respective therapeutic needs were minor in 52% and 55% and major in 48% and 45%. Eighty per cent of patients in (a), 67% in (b), and 17% in (c) required only conservative measures at six years. A decreasing lower oesophageal sphincter pressure (p < 0.001), radiological reflux (p = 0.028), and erosive oesophagitis (p = 0.031), but not initial clinical scores, were independent predictors of major therapeutic need as shown by multivariate analysis. The long term outcome of GORD is better than previously perceived.
A transmission line equivalent circuit model for strip gratings is used to determine the performance of both conducting and resistive gratings. A polarization sensitive Salisbury screen is designed in which the space cloth is replaced by a resistive grating and the ground plane is replaced by a parallel conducting grating. The new Salisbury screen performs like the traditional screen for an incident E -field parallel to the strips, but is transparent for the perpendicular polarization.