ABSTRACT
Nitrification is a central process in the global nitrogen cycle, carried out by a complex network of ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), complete ammonia-oxidizing (comammox) bacteria, and nitrite-oxidizing bacteria (NOB). Nitrification is responsible for significant nitrogen leaching and N2O emissions and thought to impede plant nitrogen use efficiency in agricultural systems. However, the actual contribution of each nitrifier group to net rates and N2O emissions remain poorly understood. We hypothesized that highly fertile agricultural soils with high organic matter mineralization rates could allow a detailed characterization of N cycling in these soils. Using a combination of molecular and activity measurements, we show that in a mixed AOA, AOB, and comammox community, AOA outnumbered low diversity assemblages of AOB and comammox 50- to 430-fold, and strongly dominated net nitrification activities with low N2O yields between 0.18 and 0.41 ng N2O-N per µg NOx-N in cropped, fallow, as well as native soil. Nitrification rates were not significantly different in plant-covered and fallow plots. Mass balance calculations indicated that plants relied heavily on nitrate, and not ammonium as primary nitrogen source in these soils. Together, these results imply AOA as integral part of the nitrogen cycle in a highly fertile agricultural soil.
ABSTRACT
The British Society of Echocardiography (BSE) highlights the importance of patient questionnaires as part of the quality improvement process, To this end, we implemented a novel system whereby paired surveys were completed by patients and physiologists for transthoracic echocardiography scans, allowing for parallel comparison of the experiences of service providers and end users. Anonymised questionnaires were completed for each scan by the patient and physiologist for outpatient echocardiographic scans in a teaching hospital. In 26% of the responses, patient found the scans at least slightly painful, and in 24% of scans physiologists were in discomfort. The most common reason given by physiologists for technically difficult or inadequate scans was patient discomfort. In 38% of the scans at least one person (the patient or the physiologist) was in at least some discomfort. Comparative data showed that the scans reported as most painful by patients were also reported by the physiologists as difficult and uncomfortable. In summary, these results demonstrate the feasibility of implementing paired surveys. Patient information leaflets by the BSE and National Health Service (NHS) describe echocardiography as painless but the results here indicate this is not always the case.
