Maintaining intensive agriculture overlying aquifers using the threshold nitrate root-uptake phenomenon.

Reducing nitrate leaching from agricultural land to aquifers has been a high priority concern for more than a half century. This study presents theory and observations of a threshold concentration of nitrate in the root zone (Cmax), which the leachate concentration increases at higher rates with increasing root-zone nitrate concentration. The value of Cmax is derived both by direct results from container experiments with varying nitrogen (N) fertigation and as a calibration parameter in N-transport models beneath commercial agricultural plots. For five different crops, Cmax ranged between 20 and 45 mg L-1 of NO3 -N derived from experiments and models. However, for lettuce (Lactuca sativa L.), which was irrigated with a large leaching fraction, Cmax could not be defined. In crops irrigated and fertilized in the warm/dry season (corn [Zea mays L.] and citrus), the experiments show a dramatic change in leachate-concentration slope, and simulations reveal a wide range of sensitivity of leachate NO3 -N concentration to Cmax. In annual crops irrigated and fertilized in the cool/wet season (e.g., potato [Solanum tuberosum L.] in a Mediterranean climate), the experiments show a distinct Cmax that is less dramatic than that of the summer-irrigated crops in the container experiment and a smaller impact of Cmax in N-transport models. The simulations show that, for summer-irrigated crops, maintaining fertigation at C < Cmax has a significant effect reducing deep leachate concentrations, whereas for the winter annual crops the simulations revealed no threshold effect. It is suggested that for summer-irrigated crops, fertigation below Cmax robustly serves the co-sustainability of intensive agriculture and aquifer water quality; this is also suggested for winter crops, but the benefits are not robust. For short-season, small root-system crops (e.g., lettuce), efforts should be made to detach the crop from the soil.

Comparative efficacy analysis of an aspiration device before primary angioplasty in patients with acute myocardial infarction: a single-center experience.

BACKGROUND: ST-elevation myocardial infarction is caused by occlusive coronary thrombosis where antecedent plaque disruption occurs. When treating STEMI the main goal is to achieve prompt reperfusion of the infarction area. Several studies have demonstrated the efficacy of an aspiration device before percutaneous coronary intervention in patients with acute myocardial infarction. OBJECTIVES: To determine the added value of thrombus aspiration prior to primary PCI by comparing AMI patients with totally occluded infarct-related artery treated with routine primary PCI to those treated with extraction device prior to primary PCI. METHODS: The study group comprised 122 consecutive patients with AMI and a totally occluded infarct artery (TIMI flow 0) who underwent primary PCI. The patients were divided into two groups: 68 who underwent primary PCI only (control group) and 54 who underwent primary thrombus extraction with an extraction device before PCI (extraction group). Baseline clinical and lesion characteristics were similar in both groups. Final TIMI grade flow and myocardial blush as well as 1 year mortality, target lesion revascularization, recurrent myocardial infarction, unstable angina and stroke were compared between the two groups. RESULTS: Primary angiographic results were better for the extraction group versus the control group: final grade 3 TIMI flow was 100% vs. 95.6% (P= 0.03) and final grade 3 myocardial blush grade 50% vs. 41.18% (although Pwas not significant). Long-term follow-up total MACE showed a nonsignificant positive trend in the extraction group (12.96% vs. 24.71%, P= 0.26). CONCLUSIONS: The use of extraction devices for intracoronary thrombectomy during primary PCI in patients with totally occluded infarct artery significantly improved epicardial reperfusion in the infarct-related vessel and showed a trend for more favorable long-term outcome.

Harnessing Paleohydrologic Modeling to Solve a Prehistoric Mystery.

A riddle arises at the Epipaleolithic and Neolithic sites that dot the lower Jordan Valley. The area has no water resources yet it has long been a focus of inquiry into the transition from mobile hunter-gatherer to sedentary agriculture-based cultures. How then is there such clear evidence of life here, and particularly at such a critical moment in human evolution? Keen to unravel this conundrum, a numerical hydrological model was devised to simulate the groundwater flow field within the Eastern Aquifer of the Judea and Samaria Mountains during the transition from the last glacial to the current interglacial. The model exhibits a range of groundwater flow regimes that prevailed in the past, demonstrating that there was once much larger groundwater discharge at these sites.