Improving accuracy of quantifying nitrate removal performance and enhancing understanding of processes in woodchip bioreactors using high-frequency data

Woodchip bioreactors have gained popularity in many countries as a conservation practice for reducing nitrate load to freshwater. However, current methods for assessing their performance may be inadequate when nitrate removal rates (RR) are determined from low-frequency (e.g., weekly) concurrent sampling at the inlet and outlet. We hypothesised that high-frequency monitoring data at multiple locations can help improve the accuracy of quantifying nitrate removal performance, enhance the understanding of processes occurring within a bioreactor, and therefore improve the design practice for bioreactors. Accordingly, the objectives of this study were to compare RRs calculated using high- and low-frequency sampling and assess the spatiotemporal variability of the nitrate removal within a bioreactor to unravel the processes occurring within a bioreactor. For two drainage seasons, we monitored nitrate concentrations at 21 locations on an hourly or two-hourly basis within a pilot-scale woodchip bioreactor in Tatuanui, New Zealand. A novel method was developed to account for the variable lag time between entry and exit of a parcel of sampled drainage water. Our results showed that this method not only enabled lag time to be accounted for but also helped quantify volumetric inefficiencies (e.g., dead zone) within the bioreactor. The average RR calculated using this method was significantly higher than the average RR calculated using conventional low-frequency methods. The average RRs of each of the quarter sections within the bioreactor were found to be different. 1-D transport modelling confirmed the effect of nitrate loading on the removal process as nitrate reduction followed Michaelis-Menten (MM) kinetics. These results demonstrate that high-frequency temporal and spatial monitoring of nitrate concentrations in the field allows improved description of bioreactor performance and better understanding of processes occurring within woodchip bioreactors. Thus, insights gained from this study can be used to optimise the design of future field bioreactors.

Reconstructing in-depth activity for chaotic 3D spatiotemporal excitable media models based on surface data

Motivated by potential applications in cardiac research, we consider the task of reconstructing the dynamics within a spatiotemporal chaotic 3D excitable medium from partial observations at the surface. Three artificial neural network methods (a spatiotemporal convolutional long-short-term-memory, an autoencoder, and a diffusion model based on the U-Net architecture) are trained to predict the dynamics in deeper layers of a cube from observational data at the surface using data generated by the Barkley model on a 3D domain. The results show that despite the high-dimensional chaotic dynamics of this system, such cross-prediction is possible, but non-trivial and as expected, its quality decreases with increasing prediction depth.

The influence of unsaturated zone drainage status on denitrification and the redox succession in shallow groundwater

Since nitrate is a major agricultural freshwater contaminant, denitrification is the environmentally most important step in the ecological succession of redox processes that can occur in groundwater. Understanding where and to what extent denitrification occurs would enable spatially differentiated land management and regulation. We investigated in a dairy farming catchment in the North Island of New Zealand the influence of the unsaturated zone's drainage status on the redox succession in shallow groundwater along a well transect spanning drainage conditions from well drained to very poorly drained. Groundwater samples were analysed for a variety of parameters including nitrate, tritium, dinitrogen, argon, methane and nitrous oxide. The redox classification based on measured redox-sensitive parameters broadly matched the a priori assessed drainage status of the overlying unsaturated zone. Only the groundwater underlying the well-drained soil was oxic and reflected the N losses from the intensive pastoral land use, with nitrate nitrogen concentrations up to 9.6 mg L^-1. All other sites had mildly to strongly reduced groundwater and concomitantly decreasing or low nitrate concentrations, even at the water table. The tritium-derived mean residence time (MRT) estimates for the oxic groundwater (12 and 14 y) were within the range found in mildly reduced groundwater from the imperfectly drained sites (6-24 y), with the exception of one sample from below an aquitard (105 y). In contrast, the strongly reduced groundwater observed at the poorly and very poorly drained sites was relatively immobile (55 to >110 y). Denitrification was confirmed by the nitrate dual isotope signatures, and by the occurrence of excess dinitrogen, and likely occurred in both the unsaturated and saturated zones. A coherent sampling scheme throughout the unsaturated zone - saturated zone continuum should be used in future studies to allow ascertaining the exact location of denitrification activity in vertical profiles.

Vertical stratification of redox conditions, denitrification and recharge in shallow groundwater on a volcanic hillslope containing relict organic matter

Natural denitrification in groundwater systems has been recognised as an ecosystem service that reduces the impact of agriculturally-derived nitrate inputs to surface waters. Identification of this ecosystem service within the landscape would permit spatially differentiated land management and legislation. However, spatial variation in groundwater redox conditions poses a significant challenge to such a concept. To gain understanding of the small-scale mosaic of biogeochemical and hydrological controls on denitrification, we established a well field consisting of 11 multilevel well (MLW) clusters on a hillslope containing relict organic matter buried by volcanic deposits 1.8 ka before present. Based on site-specific redox classification thresholds, vertical redox gradients and denitrification potentials were detected at 7 of the 11 sites. Palaeosols or woody debris, which had previously been identified in laboratory experiments as resident electron donors fuelling denitrification, were visually recognisable at 4 of the 7 MLW sites with vertical redox gradients. Moderately enhanced groundwater dissolved organic carbon (DOC) concentrations occurred where resident electron donors were evident. DOC concentrations were lower where anoxic and nitrate-depleted groundwater was found but with an absence of resident electron donors. In these instances, it was assumed that nitrate reduction had occurred somewhere upgradient of the sampled well screen along the lateral groundwater flow path, with the proximate electron donor (DOC) largely consumed in the process, since no evidence was found for denitrification being fuelled by inorganic electron donors. Due to high variability in the isotopic signature of nitrate in oxidised groundwater, the nitrate dual isotope method did not yield firm evidence for denitrification. However, realistic vertical patterns were obtained using the excess N₂ method. Tritium-based age dating revealed that oxic conditions were restricted to young groundwater (mean residence time ≤ 3 y), while anoxic conditions were observed across a wider age range (3-25 y).

Aligning provider incentives to improve primary healthcare delivery in the United States

BACKGROUND

The United States (US) is reforming primary care delivery systems, including the implementation of 'patient-centered medical homes.' Alignment of provider incentives with desired outcomes will likely be important to the success of these delivery system reforms.

METHODS

This critical review uses a theoretical framework from game-theory models to discuss some of the dominant primary care provider payment models and how they create 'prisoner's dilemmas' that have stalled past reform efforts. It then uses this framework to illustrate, hypothetically, how advantages from different models could be blended together to encourage cooperation and improve the quality of primary care services delivered, thus providing an escape from current prisoner's dilemmas faced by providers.

FINDINGS

Improvements in primary care delivery will largely hinge on blended payment mechanisms that can effectively combine the advantageous elements of fee-for-service, capitation, and incentive payments into a balanced equation that enables providers to escape the perverse financial incentives of current payment mechanisms and overcome collective action problems.

CONCLUSIONS

If balanced appropriately, a blend of guaranteed payment and selective incentives designed to encourage primary care providers to deliver high quality care, efficient and equitable care and to eliminate incentives towards over-servicing could reach outcomes leading to shared benefits for everyone involved.

The impact of relict organic materials on the denitrification capacity in the unsaturated-saturated zone continuum of three volcanic profiles

The denitrification capacity of wetlands, riparian zones, and aquifers in glacial outwash areas is well documented, but little or no information exists for volcanic profiles, particularly those containing relict organic matter contained in or on top of paleosols (old soils buried by volcanic deposits) below the groundwater table. Relict carbon contained in these layers could provide the necessary electrons to fuel heterotrophic denitrification. To the best of our knowledge, this is the first study investigating the denitrification capacity in both the unsaturated and saturated zone of volcanic profiles. Samples from three profile types with differing organic matter distribution were amended with N-enriched nitrate (NO-) and incubated in the laboratory under anaerobic conditions. Dinitrogen (N) dominated the N gas fluxes; averaged across all samples, it accounted for 96% of the total N (nitrous oxide [NO] and N) gas fluxes. Dinitrogen fluxes were generally highest in the A horizon samples (4.1-6.2 nmol N g h), but substantial fluxes were also observed in some paleosol layers (up to 0.72 nmol N g h). A significant correlation ( < 0.001) was found between the concentration of extractable dissolved organic carbon and the total N gas flux produced in samples from below the A horizon, suggesting that heterotrophic denitrification was the dominant NO attenuation process in this study. Extrapolation of lab-derived denitrification capacities to field conditions suggests that the denitrification capacity of profiles containing relict soil organic matter in the saturated zone exceeds the estimated N leaching from the root zone.

[Correlation between sex, intrauterine position and familial predisposition and neonatal hip ultrasound results]

AIM

To correlate findings of hip ultrasound on day 4-10 of life with sex, intrauterine position and a positive family history for congenital hip anomalies.

METHODS

The SNiP-study ( Survey of Neonates In Pommerania) registered 2256 neonates (2030 term, 226 preterm) between May 2002 and March 2004. Hip ultrasound results of 1043 term and since October 2003 33 preterm neonates were analysed. Time of ultrasound was day 4-10 after birth. Preterm neonates were examined when reaching their corrected term gestational age. Ultrasound was applied with a 7.5 MHz linear scanner and results were classified according to Graf. Chi-square and Fishers exact test were used for statistical analysis.

RESULTS

4.9 % of the screened hips were classified as IIc or higher, 3.1 % were unilateral and 1.7 % bilateral. Incidence was significantly higher (p < 0.023) in females (6.6 %) than in males (3.2 %). There was no significant difference in intrauterine position or positive family history for hip anomalies with 3.7 % for mothers, 1.2 % of fathers and 2.4 % of siblings positive. There was a higher incidence for congenital hip dysplasia in preterms with 6.1 %, which is not significant due to the limited number.

DISCUSSION

Current screening methods miss up to 18 % of newborns with severe hip dysplasia. We were able to demonstrate that screening for congenital hip dysplasia with ultrasound is a diagnostic tool even during the first days of life. There is a significantly higher incidence of congenital hip dysplasia in females, but in contrast to other studies we found no significant difference in intrauterine position or familial history. Earlier diagnosis and therapy on the base of relevant risk factors might correspond with an improved prognosis and outcome. Further studies are warranted to evaluate the significance in preterm neonates.

Lack of sex difference in cerebrospinal fluid (CSF) leptin levels and contribution of CSF/plasma ratios to variations in body mass index in children

In adults, leptin seems to cross the blood-brain barrier by a saturable transporter. This may contribute to the development of obesity. The present study in healthy children investigates leptin levels in plasma and cerebrospinal fluid (CSF) in relation to body constitution. This prospective study analyzed leptin levels in plasma and CSF samples (stored at -80 C) of patients without CNS infection or blood-brain barrier dysfunction. Inclusion criteria included temperature less than 38.5 C, C-reactive protein levels below 10 mg/L, CSF leukocyte levels less than 10(7)/L, no need for neurosurgical or oncological treatment, and no history of trauma. Four groups were designated according to body mass index. Sixty-five children (28 girls and 37 boys) entered the study. Plasma leptin (median) was 7.4 in girls and 2.6 ng/mL in boys., CSF leptin was 0.273 and 0.204 ng/mL, respectively, leading to CSF/plasma ratios of 0.045 and 0.071, respectively. Ratios were clearly dependent on body mass index percentiles (r = -0.484; P < 0.01, significant differences between groups by ANOVA). Median plasma leptin levels in the 4 groups (body mass index, <10th, 10th-50th, 50th-90th, and >90th percentile) were 2.0, 2.3, 4.1, and 8.8 ng/mL; CSF/plasma ratios were inversely related: 8.2%, 7.6%, 5.5% and 3.6%. In healthy children, CSF leptin levels account for approximately 5% of plasma levels. CSF/plasma ratios in girls are lower than those in boys, explaining why calorie intake and energy expenditure are not grossly different despite large differences in circulating plasma leptin concentrations. CSF/plasma ratios of lean children are higher than those in obese children. The dynamic changes in the CSF/plasma ratios are more pronounced in lean children, i.e. the nonlinear transport characteristics of the leptin system amplifies the information about changes in body energy stores in this population, indicating that leptin is part of a mechanism to protect the body from critical weight loss rather than to avoid obesity.

Serum eosinophil cationic protein measurements in the management of perennial and periodic asthma: a prospective study

We performed a prospective study in order: 1) to determine whether a correlation could be found between serum eosinophil cationic protein (ECP) levels and clinical and functional status in perennial asthmatics during a 5 month prospective study; and 2) to evaluate the relationship between allergic exposure and ECP levels in periodic asthmatics. Two groups of asthmatic patients were selected: a group of acutely ill perennial asthmatics and a group of periodic asthmatics. The acutely ill perennial asthmatics (n=22, mean age=39.4 yrs) were included on the basis of hospitalization for acute asthma. At the end of the hospitalization, there was a 5 month follow-up of clinical, functional and medication scores, as well as eosinophil counts and ECP levels. The periodic asthmatic group was composed of asthmatics sensitized to birch and tree pollens (n=10, mean age=33.8 yrs). The same measurement were performed on this group, before, during and after the pollen season. Under corticosteroid treatment in the acutely ill patients, there was a significant decrease in serum ECP levels between the first day of hospitalization and the day of discharge (mean: 23.2 microg x L(-1) and 9.5 microg x L(-1), respectively; p=0.006). No correlation was found between the clinical status, functional status and serum ECP levels during the 5 month follow-up. A significant increase in ECP levels was found in periodic asthmatics during the pollen season. Our results suggest that serum eosinophil cationic protein is a useful marker of allergen exposure and of acute asthma treatment. This could be of importance in the prevention and follow-up of allergic asthma; the value of serum eosinophil cationic protein measurements in the day-to-day management of adult asthmatics needs to be further clarified.

Serum eosinophil cationic protein measurements in the management of perennial and periodic asthma: a prospective study

We performed a prospective study in order: 1) to determine whether a correlation could be found between serum eosinophil cationic protein (ECP) levels and clinical and functional status in perennial asthmatics during a 5 month prospective study; and 2) to evaluate the relationship between allergic exposure and ECP levels in periodic asthmatics. Two groups of asthmatic patients were selected: a group of acutely ill perennial asthmatics and a group of periodic asthmatics. The acutely ill perennial asthmatics (n=22, mean age=39.4 yrs) were included on the basis of hospitalization for acute asthma. At the end of the hospitalization, there was a 5 month follow-up of clinical, functional and medication scores, as well as eosinophil counts and ECP levels. The periodic asthmatic group was composed of asthmatics sensitized to birch and tree pollens (n=10, mean age=33.8 yrs). The same measurement were performed on this group, before, during and after the pollen season. Under corticosteroid treatment in the acutely ill patients, there was a significant decrease in serum ECP levels between the first day of hospitalization and the day of discharge (mean: 23.2 microg x L(-1) and 9.5 microg x L(-1), respectively; p=0.006). No correlation was found between the clinical status, functional status and serum ECP levels during the 5 month follow-up. A significant increase in ECP levels was found in periodic asthmatics during the pollen season. Our results suggest that serum eosinophil cationic protein is a useful marker of allergen exposure and of acute asthma treatment. This could be of importance in the prevention and follow-up of allergic asthma; the value of serum eosinophil cationic protein measurements in the day-to-day management of adult asthmatics needs to be further clarified.

[Asthma, rhinitis and urticaria following occupational exposure to cyanoacrylate glues]

Cyanoacrylate glues are more and widely used in the industry because of easy handling and great sticking power. These very volatile and chemically reactive glues may not only cause contact eczema, but also rhinitis and asthma. Nineteen cases of asthma have been reported to date. We report two new cases of occupational asthma as well as one case of urticaria, a clinical symptom not yet described, to our knowledge. In the three cases, diagnosis was made based on a compatible medical history and positive realistic exposure tests. The mechanism is still unknown, due to the physical properties of cyanoacrylate glues; in fact, it is not possible to perform prick tests or specific IgE measurements. Besides the usual preventive measures, maintaining a relative humidity greater than 55% seems to induce polymerization of free monomers of alkyl cyanoacrylate, thereby reducing their volatility. Rhinitis and asthma due to cyanoacrylate glue may receive compensation as occupational diseases in France.

Platelet-derived growth factor in asthma

Platelet-derived growth factor (PDGF) controls cellular growth, migration, and differentiation. It is secreted by various cell types, including macrophages, and participates in tissue repair and epithelial regeneration. PDGF may therefore be involved in airway remodeling in asthma. This study compared the immunoreactivity of PDGF and its receptors (R alpha and R beta) in bronchial biopsies and the levels of PDGF in bronchoalveolar lavage (BAL) fluid of asthmatics and control subjects. Bronchial biopsies were done in a subsegmental bronchus of 11 asthmatics and 11 control subjects by flexible bronchoscope. PDGF AA and BB, and PDGF receptors R alpha and R beta were studied with monoclonal antibodies and revealed by immunoperoxidase staining. The percentage of subjects presenting positive staining with PDGFs and its receptors was studied in the epithelium and submucosa. PDGF AA, AB, and BB were measured in BAL fluid of 18 asthmatics and 10 controls by specific ELISA. In biopsies, there was no significant difference between asthmatics and controls for PDGF AA, BB, PDGF-R alpha and R beta (Fisher's exact test and Bonferroni's correction). Moreover, the levels of PDGF, AA, AB, and BB were similar in asthmatics and controls. This study does not support a role for PDGF in the repair processes of asthma.

Cyfra 21-1 as a biologic marker of non-small cell lung cancer. Evaluation of sensitivity, specificity, and prognostic role

BACKGROUND

Cytokeratins are epithelial markers whose expression is not lost during malignant transformation. Cyfra 21-1 is a cytokeratin-19 fragment that is soluble in serum and may be a useful circulating tumor marker.

STUDY OBJECTIVE

The aims of this study were (1) to confirm sensitivity and specificity of Cyfra 21-1 in detecting non-small cell lung cancer (NSCLC) and especially the squamous cell subtype, (2) to assess the potential relationship between Cyfra 21-1 and disease stage of the disease in NSCLC, and (3) to evaluate prognostic effect of Cyfra 21-1 in NSCLC.

METHODS

An immunoradiometric assay of serum Cyfra 21-1 was performed in 161 patients with lung cancers and 71 others with benign lung diseases. The ability of Cyfra 21-1 to detect different histologic subtypes of lung cancer vs benign lung diseases was assessed through receiver operating characteristic (ROC) curves and comparisons with other tumor markers such as carcinoembryonic antigen, neuron-specific enolase, and squamous cell carcinoma antigen. Comparisons of Cyfra 21-1 levels according to histologic subtype and disease stage were done using Kruskal-Wallis test. Independent prognostic value of Cyfra 21-1 was studied with a multivariate analysis of survival (Cox's model).

RESULTS

Using a threshold of 3.3 ng/mL for Cyfra 21-1, sensitivity and specificity were, respectively, 0.59 and 0.94 in NSCLC, 0.68 and 0.94 in the subgroup of the squamous cell carcinoma, and 0.19 and 0.94 in small cell lung cancer. Cyfra 21-1 levels were significantly higher in advanced NSCLC than in early-stage disease. All 29 patients with serum concentrations > 32 ng/mL had stage IIIB-IV and only one of 14 patients with stage I-II disease had Cyfra 21-1 level > 18 ng/mL. In the multivariate analysis of survival, Cyfra 21-1 was an independent prognostic factor along with performance status and disease stage in NSCLC.

CONCLUSIONS

Cyfra 21-1 is a sensitive and specific tumor marker of NSCLC, especially of squamous cell subtype. It also reflects the extent of the disease and has an independent prognostic role along with performance status and disease stage in NSCLC.

IMPLICATIONS

A high level of Cyfra 21-1 in apparently early-stage NSCLC should be an indication for more extensive workup before thoracotomy. The independent prognostic role of Cyfra 21-1 level may be useful in stratifying populations with advanced NSCLC or early-stage resected NSCLC as elevated Cyfra 21-1 levels might identify those patients at high risk for treatment failure.

Increase in blood-brain barrier permeability by altitude decompression

Previous studies indicated that exposure to compression-decompression increases blood-brain barrier (BBB) permeability to vital dyes and antibiotics. This report concerns functional and ultrastructural BBB changes induced by altitude decompression. A 2% trypan blue solution was intravenously injected (4 ml.kg-1) into 29 experimental and 19 control rabbits. Some animals also received horseradish peroxidase. The experimental animals were subjected to 30,000 ft (4.3 psi) for 45 min. Controls were kept at ground level. The animals were sacrificed 90 min postinjection. Gross and microscopic examination and spectrophotometric dye determination revealed significantly greater tracer penetration in experimental brains (mean dye concentration 27.06 +/- 4.42 micrograms.g-1) than in controls (4.52 +/- 1.52 micrograms.g-1). No sex differences were noted. Electron microscopy suggested that the increased BBB permeability was due to transendothelial vesicular transport and, occasionally, to penetration through interendothelial junctions. These observations may have relevance to pharmacotherapy in space and at high altitudes and to the pathogenesis of altitude decompression sickness.