Subsurface nitrate reduction under wetlands takes place in narrow superficial zones

This study aims to investigate the depth distribution of the Nitrate Reduction Potential (NRP) on a natural and a re-established wetland. The obtained NRP provides a valuable data of the driving factors affecting denitrification, the Dissimilatory Nitrate Reduction to Ammonium (DNRA) process and the performance of a re-established wetland. Intact soil cores were collected and divided in slices for the determination of Organic Matter (OM) through Loss of Ignition (LOI) as well as Dissolved Organic Carbon (DOC) and NRP spiking nitrate in batch tests. The Nitrate Reduction (NR) was fitted as a pseudo-first order rate constant (k) from where NRPs were obtained. NR took place in a narrow superficial zone showing a dropping natural logarithmic trend along depth. The main driving factor of denitrification, besides depth, was OM. Although, DOC and LOI could not express by themselves and absolute correlation with NRP, high amounts of DOC ensured enough quantity and quality of labile OM for NR. Besides, high concentration of LOI but a scarce abundance of DOC failed to drive NR. DNRA was only important in superficial samples with high contents of OM. Lastly, the high NRP of the re-established wetland confirms that wetlands can be restored satisfactorily.Preprin

Right ventricular failure after implantation of a continuous-flow left ventricular assist device: early haemodynamic predictors †

Abstract OBJECTIVES: Right ventricular failure (RVF) is a significant complication after implantation of a left ventricular assist device. We aimed to identify haemodynamic changes in the early postoperative phase that predicted subsequent development of RVF in a cohort of HeartMate II (HMII) implanted patients. METHODS: This was a single-centre observational study of consecutive placement of HMII devices at Rigshospitalet, Copenhagen. Preoperative data (right heart catheterization, biochemistry and clinical status) and postoperative readings from the first 72 h after implantation (haemodynamics, inotropic and vasoactive therapy) were included in the analysis. The data set was examined for significant differences between patients who developed RVF (RVF group, n = 11)-defined as need for inotropic or vasodilator therapy >14 days, nitric oxide therapy ≥48 h or right ventricular assist device therapy-and those who did not (non-RVF group, n = 22). RESULTS: Preoperative right heart catheterization data were similar in the two groups. Immediately after HMII implantation, the increase in cardiac index (CI) was significantly larger in the non-RVF than in the RVF group (0.96 ± 0.8 vs 0.2 ± 0.5 L/min, respectively; P = 0.018), whereas right ventricular stroke work index (RVSWI) decreased significantly more in the RVF group (−4.3 ± 2.0 vs −0.9 ± 2.0 g m/m 2 ; P < 0.001). These differences were present in spite of the RVF group receiving larger doses of catecholaminergic agents (P = 0.034). Over the ensuing 72 h, the CI of the RVF group gradually approached that of the non-RVF group; concurrently, however, the differences in inotropic therapy were further enhanced. Pump settings were similar in the two groups. CONCLUSIONS: The haemodynamic alterations characterizing RVF were present already immediately after HMII implantation. RVF development was not related to pump flow and settings

Ab initio van der Waals interactions in simulations of water alter structure from mainly tetrahedral to high-density-like

The structure of liquid water at ambient conditions is studied in ab initio molecular dynamics simulations using van der Waals (vdW) density-functional theory, i.e. using the new exchange-correlation functionals optPBE-vdW and vdW-DF2. Inclusion of the more isotropic vdW interactions counteracts highly directional hydrogen-bonds, which are enhanced by standard functionals. This brings about a softening of the microscopic structure of water, as seen from the broadening of angular distribution functions and, in particular, from the much lower and broader first peak in the oxygen-oxygen pair-correlation function (PCF), indicating loss of structure in the outer solvation shells. In combination with softer non-local correlation terms, as in the new parameterization of vdW-DF, inclusion of vdW interactions is shown to shift the balance of resulting structures from open tetrahedral to more close-packed. The resulting O-O PCF shows some resemblance with experiment for high-density water (A. K. Soper and M. A. Ricci, Phys. Rev. Lett., 84:2881, 2000), but not directly with experiment for ambient water. However, an O-O PCF consisting of a linear combination of 70% from vdW-DF2 and 30% from experiment on low-density liquid water reproduces near-quantitatively the experimental O-O PCF for ambient water, indicating consistency with a two-liquid model with fluctuations between high- and low-density regions

Osteonecrosis following resurfacing arthroplasty: A clinical positron emission tomography study of 14 cases

Background and purpose One of the main concerns regarding resurfacing arthroplasty is the viability of the remaining part of the femoral head, and the postoperative risk of a femoral neck fracture or collapse. In contrast to radiographic methods, positron emission tomography using the radiotracer [18F]-fluoride (Fluoride-PET) enables us to visualize the viability of bone in the remaining part of the head, despite the presence of the covering metal component

Costs of shoulder pain and resource use in primary health care: a cost-of-illness study in Sweden

<p>Abstract</p> <p>Background</p> <p>Painful shoulders pose a substantial socioeconomic burden. A prospective cost-of-illness study was performed to assess the costs associated with healthcare use and loss of productivity in patients with shoulder pain in primary health care in Sweden.</p> <p>Methods</p> <p>The study was performed in western Sweden, in a region with 24 000 inhabitants. Data were collected during six months from electronic patient records at three primary healthcare centres in two municipalities. All patients between 20 and 64 years of age who presented with shoulder pain to a general practitioner or a physiotherapist were included. Diagnostic codes were used for selection, and the cases were manually controlled. The cost for sick leave was calculated according to the human capital approach. Sensitivity analysis was used to explore uncertainty in various factors used in the model.</p> <p>Results</p> <p>204 (103 women) patients, mean age 48 (SD 11) years, were registered. Half of the cases were closed within six weeks, whereas 32 patients (16%) remained in the system for more than six months. A fifth of the patients were responsible for 91% of the total costs, and for 44% of the healthcare costs. The mean healthcare cost per patient was €326 (SD 389) during six months. Physiotherapy treatments accounted for 60%. The costs for sick leave contributed to 84% of the total costs. The mean annual total cost was €4139 per patient. Estimated costs for secondary care increased the total costs by one third.</p> <p>Conclusions</p> <p>The model applied in this study provides valuable information that can be used in cost evaluations. Costs for secondary care and particularly for sick leave have a major influence on total costs and interventions that can reduce long periods of sick leave are warranted.</p