Comparison of two closed-path cavity-based spectrometers for measuring air-water CO<inf>2</inf> and CH<inf>4</inf> fluxes by eddy covariance

In recent years several commercialised closed-path cavity-based spectroscopic instruments designed for eddy covariance flux measurements of carbon dioxide (CO2), methane (CH4), and water vapour (H2O) have become available. Here we compare the performance of two leading models - the Picarro G2311-f and the Los Gatos Research (LGR) Fast Greenhouse Gas Analyzer (FGGA) at a coastal site. Both instruments can compute dry mixing ratios of CO2 and CH4 based on concurrently measured H2O, temperature, and pressure. Additionally, we used a high throughput Nafion dryer to physically remove H2O from the Picarro airstream. Observed air-sea CO2 and CH4 fluxes from these two analysers, averaging about 12 and 0.12 mmol m-2 day-1 respectively, agree within the measurement uncertainties. For the purpose of quantifying dry CO2 and CH4 fluxes downstream of a long inlet, the numerical H2O corrections appear to be reasonably effective and lead to results that are comparable to physical removal of H2O with a Nafion dryer in the mean. We estimate the high-frequency attenuation of fluxes in our closed-path set-up, which was relatively small (≤ 10 %) for CO2 and CH4 but very large for the more polar H2O. The Picarro showed significantly lower noise and flux detection limits than the LGR. The hourly flux detection limit for the Picarro was about 2 mmol m-2 day-1 for CO2 and 0.02 mmol m-2 day-1 for CH4. For the LGR these detection limits were about 8 and 0.05 mmol m-2 day-1. Using global maps of monthly mean air-sea CO2 flux as reference, we estimate that the Picarro and LGR can resolve hourly CO2 fluxes from roughly 40 and 4 % of the world's oceans respectively. Averaging over longer timescales would be required in regions with smaller fluxes. Hourly flux detection limits of CH4 from both instruments are generally higher than the expected emissions from the open ocean, though the signal to noise of this measurement may improve closer to the coast

Which is more useful in predicting hospital mortality - dichotomised blood test results or actual test values? A retrospective study in two hospitals

Routine blood tests are an integral part of clinical medicine and in interpreting blood test results clinicians have two broad options. (1) Dichotomise the blood tests into normal/abnormal or (2) use the actual values and overlook the reference values. We refer to these as the "binary" and the "non-binary" strategy respectively. We investigate which strategy is better at predicting the risk of death in hospital based on seven routinely undertaken blood tests (albumin, creatinine, haemoglobin, potassium, sodium, urea, and white blood cell count) using tree models to implement the two strategies

Arctic summer airmass transformation, surface inversions, and the surface energy budget

During the Arctic Clouds in Summer Experiment (ACSE) in summer 2014 a weeklong period of warm-air advection over melting sea ice, with the formation of a strong surface temperature inversion and dense fog, was observed. Based on an analysis of the surface energy budget, we formulated the hypothesis that, because of the airmass transformation, additional surface heating occurs during warm-air intrusions in a zone near the ice edge. To test this hypothesis, we explore all cases with surface inversions occurring during ACSE and then characterize the inversions in detail. We find that they always occur with advection from the south and are associated with subsidence. Analyzing only inversion cases over sea ice, we find two categories: one with increasing moisture in the inversion and one with constant or decreasing moisture with height. During surface inversions with increasing moisture with height, an extra 10–25 W m−2 of surface heating was observed, compared to cases without surface inversions; the surface turbulent heat flux was the largest single term. Cases with less moisture in the inversion were often cloud free and the extra solar radiation plus the turbulent surface heat flux caused by the inversion was roughly balanced by the loss of net longwave radiation

An evaluation of POSSUM and P-POSSUM scoring in predicting post-operative mortality in a level 1 critical care setting

Background POSSUM and P-POSSUM are used in the assessment of outcomes in surgical patients. Neither scoring systems’ accuracy has been established where a level 1 critical care facility (level 1 care ward) is available for perioperative care. We compared POSSUM and P-POSSUM predicted with observed mortality on a level 1 care ward. Methods A prospective, observational study was performed between May 2000 and June 2008. POSSUM and P-POSSUM scores were calculated for all postoperative patients who were admitted to the level 1 care ward. Data for post-operative mortality were obtained from hospital records for 2552 episodes of patient care. Observed vs expected mortality was compared using receiver operating characteristic (ROC) curves and the goodness of fit assessed using the Hosmer-Lemeshow equation. Results ROC curves show good discriminative ability between survivors and non-survivors for POSSUM and P-POSSUM. Physiological score had far higher discrimination than operative score. Both models showed poor calibration and poor goodness of fit (Hosmer-Lemeshow). Observed to expected (O:E) mortality ratio for POSSUM and P-POSSUM indicated significantly fewer than expected deaths in all deciles of risk. Conclusions Our data suggest a 30-60% reduction in O:E mortality. We suggest that the use of POSSUM models to predict mortality in patients admitted to level 1 care ward is inappropriate or that a recalibration of POSSUM is required to make it useful in a level 1 care ward setting

Motivation and incentives of rural maternal and neonatal health care providers: a comparison of qualitative findings from Burkina Faso, Ghana and Tanzania.

In Burkina Faso, Ghana and Tanzania strong efforts are being made to improve the quality of maternal and neonatal health (MNH) care. However, progress is impeded by challenges, especially in the area of human resources. All three countries are striving not only to scale up the number of available health staff, but also to improve performance by raising skill levels and enhancing provider motivation. In-depth interviews were used to explore MNH provider views about motivation and incentives at primary care level in rural Burkina Faso, Ghana and Tanzania. Interviews were held with 25 MNH providers, 8 facility and district managers, and 2 policy-makers in each country. Across the three countries some differences were found in the reasons why people became health workers. Commitment to remaining a health worker was generally high. The readiness to remain at a rural facility was far less, although in all settings there were some providers that were willing to stay. In Burkina Faso it appeared to be particularly difficult to recruit female MNH providers to rural areas. There were indications that MNH providers in all the settings sometimes failed to treat their patients well. This was shown to be interlinked with differences in how the term 'motivation' was understood, and in the views held about remuneration and the status of rural health work. Job satisfaction was shown to be quite high, and was particularly linked to community appreciation. With some important exceptions, there was a strong level of agreement regarding the financial and non-financial incentives that were suggested by these providers, but there were clear country preferences as to whether incentives should be for individuals or teams. Understandings of the terms and concepts pertaining to motivation differed between the three countries. The findings from Burkina Faso underline the importance of gender-sensitive health workforce planning. The training that all levels of MNH providers receive in professional ethics, and the way this is reinforced in practice require closer attention. The differences in the findings across the three settings underscore the importance of in-depth country-level research to tailor the development of incentives schemes

Atmospheric conditions during the Arctic Clouds in Summer Experiment (ACSE): Contrasting open-water and sea-ice surfaces during melt and freeze-up seasons

The Arctic Clouds in Summer Experiment (ACSE) was conducted during summer and early autumn 2014, providing a detailed view of the seasonal transition from ice melt into freeze-up. Measurements were taken over both ice-free and ice-covered surfaces near the ice edge, offering insight into the role of the surface state in shaping the atmospheric conditions. The initiation of the autumn freeze-up was related to a change in air mass, rather than to changes in solar radiation alone; the lower atmosphere cooled abruptly, leading to a surface heat loss. During melt season, strong surface inversions persisted over the ice, while elevated inversions were more frequent over open water. These differences disappeared during autumn freeze-up, when elevated inversions persisted over both ice-free and ice-covered conditions. These results are in contrast to previous studies that found a well-mixed boundary layer persisting in summer and an increased frequency of surface-based inversions in autumn, suggesting that knowledge derived from measurements taken within the pan-Arctic area and on the central ice pack does not necessarily apply closer to the ice edge. This study offers an insight into the atmospheric processes that occur during a crucial period of the year; understanding and accurately modeling these processes is essential for the improvement of ice-extent predictions and future Arctic climate projections

Effects of a four-year health systems intervention on the use of maternal and infant health services: results from a programme evaluation in two districts of rural Chad

BACKGROUND: Attendance of maternal and infant care services in rural Chad are consistently low. Our study aimed to assess the use of antenatal (ANC) and postnatal care (PNC) services, health facility delivery and infant health services after 4 years of a health systems intervention for improving the infrastructure, supplies, training and sensitization for maternal and infant health in two districts of rural Chad. METHODS: Data from a repeated cross-sectional household survey conducted in Yao and Danamadji in 2015 and in 2018 were analyzed. A stratified two-stage cluster sampling methodology was applied to achieve a representative sample of the rural settled and mobile population groups in the study area. A generalized linear model was applied to determine the health care utilization rates. Multivariate regression models were used to assess the association between the programme intervention and utilization outcomes of selected maternal and infant health services. RESULTS: Complete datasets were available for 1284 households at baseline. The endline analysis included 1175 households with complete survey data. The use of at least one ANC amongst pregnant women increased in both settled communities (from 80% in 2015 to 90% in 2018) and amongst mobile pastoralist communities (from 48% in 2015 to 56% in 2018). The rate of home delivery among settled communities and mobile pastoralists changed little between baseline and endline and remained high for both population groups. Individuals that were covered by the health systems intervention were however significantly more likely to attend ANC and less likely to give birth at home. PNC services only showed improvements amongst the settled communities (of 30%). Infants' reported health outcomes and vaccination coverage considerably improved; the latter especially among mobile pastoralist (from 15% in 2015 to 84% in 2018). CONCLUSION: A combination of health systems strengthening interventions was associated with an increased use of certain maternal and infant health services. However, to facilitate equitable access to and use of health care services in particular in times of increased vulnerability and by certain population groups in hard-to-reach areas, reinforced health education and culturally adapted communication strategies, including gender-specific messaging will be needed over a sustained period

Weekend admission and mortality from acute exacerbations of chronic obstructive pulmonary disease in winter

Historically, acute medical staffing numbers have been lower on weekends and in winter numbers of medical admissions rise. An analysis of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) admissions to Portsmouth Hospitals over a seven-year period was undertaken to examine the effects of admission on a weekend, of winter, and with the opening of a medical admissions unit (MAU). In total, 9,915 admissions with AECOPD were identified. Weekend admissions accounted for 2,071 (20.9%) of cases, winter accounted for 3,026 (30.5%) admissions, and 522 (34.4%) deaths. Adjusted odds ratio (OR) for death on day 1 after winter weekend admission was 2.89 (95% confidence interval (CI) 1.035 to 8.076). After opening the MAU, the OR for death day 1 after weekend winter admission fell from 3.63 (95% CI 1.15 to 11.5) to 1.65 (95% CI 0.14 to 19.01). AECOPD patients have an increased risk of death after admission over a weekend in winter and this effect was reduced by opening a MAU. These findings have implications for the planning of acute care provision in different seasons. © Royal College of Physicians, 2011. All rights reserved