There is a need to increase access to surgical treatments in African countries, but perioperative complications represent a major global health-care burden. There are few studies describing surgical ...outcomes in Africa.
We did a 7-day, international, prospective, observational cohort study of patients aged 18 years and older undergoing any inpatient surgery in 25 countries in Africa (the African Surgical Outcomes Study). We aimed to recruit as many hospitals as possible using a convenience sampling survey, and required data from at least ten hospitals per country (or half the surgical centres if there were fewer than ten hospitals) and data for at least 90% of eligible patients from each site. Each country selected one recruitment week between February and May, 2016. The primary outcome was in-hospital postoperative complications, assessed according to predefined criteria and graded as mild, moderate, or severe. Data were presented as median (IQR), mean (SD), or n (%), and compared using t tests. This study is registered on the South African National Health Research Database (KZ_2015RP7_22) and ClinicalTrials.gov (NCT03044899).
We recruited 11 422 patients (median 29 IQR 10–70) from 247 hospitals during the national cohort weeks. Hospitals served a median population of 810 000 people (IQR 200 000–2 000 000), with a combined number of specialist surgeons, obstetricians, and anaesthetists totalling 0·7 (0·2–1·9) per 100 000 population. Hospitals did a median of 212 (IQR 65–578) surgical procedures per 100 000 population each year. Patients were younger (mean age 38·5 years SD 16·1), with a lower risk profile (American Society of Anesthesiologists median score 1 IQR 1–2) than reported in high-income countries. 1253 (11%) patients were infected with HIV, 6504 procedures (57%) were urgent or emergent, and the most common procedure was caesarean delivery (3792 patients, 33%). Postoperative complications occurred in 1977 (18·2%, 95% CI 17·4–18·9) of 10 885 patients. 239 (2·1%) of 11 193 patients died, 225 (94·1%) after the day of surgery. Infection was the most common complication (1156 10·2% of 10 970 patients), of whom 112 (9·7%) died.
Despite a low-risk profile and few postoperative complications, patients in Africa were twice as likely to die after surgery when compared with the global average for postoperative deaths. Initiatives to increase access to surgical treatments in Africa therefore should be coupled with improved surveillance for deteriorating physiology in patients who develop postoperative complications, and the resources necessary to achieve this objective.
Medical Research Council of South Africa.
The promotion of physical activity (PA) guidelines to the general public is an important issue that lacks empirical investigation. PA campaigns often feature participation thresholds that cite PA ...guidelines verbatim e.g., 150 min/week moderate-to-vigorous physical activity (MVPA). Some campaigns instead prefer to use generic PA messages (e.g., do as much MVPA as possible). 'Thresholds' may disrupt understanding of the health benefits of modest PA participation. This study examined the perception of health benefits of PA after exposure to PA messages that did and did not contain a duration threshold.
Brief structured interviews were conducted with a convenience sample of adults (n = 1100). Participants received a threshold message (150 min/week MVPA), a message that presented the threshold as a minimum; a generic message or no message. Participants rated perceived health effects of seven PA durations. One-way analyses of variance with post hoc tests for group differences were used to assess raw perception ratings for each duration of PA.
Recipients of all three messages held more positive perceptions of >150 min/week of MVPA relative to those not receiving any message. For MVPA durations <150 min/week, the generic PA message group perceived the greatest health benefits. Those receiving the threshold message tended to have the least positive perceptions of durations <150 min/week.
Threshold messages were associated with lower perceived health benefits for modest PA durations. Campaigns based on threshold messages may be limited when promoting small PA increases at a population level.
Over the past 24 years, the AErosol RObotic NETwork (AERONET) program has provided highly accurate remote-sensing characterization of aerosol optical and physical properties for an increasingly ...extensive geographic distribution including all continents and many oceanic island and coastal sites. The measurements and retrievals from the AERONET global network have addressed satellite and model validation needs very well, but there have been challenges in making comparisons to similar parameters from in situ surface and airborne measurements. Additionally, with improved spatial and temporal satellite remote sensing of aerosols, there is a need for higher spatial-resolution ground-based remote-sensing networks. An effort to address these needs resulted in a number of field campaign networks called Distributed Regional Aerosol Gridded Observation Networks (DRAGONs) that were designed to provide a database for in situ and remote-sensing comparison and analysis of local to mesoscale variability in aerosol properties. This paper describes the DRAGON deployments that will continue to contribute to the growing body of research related to meso- and microscale aerosol features and processes. The research presented in this special issue illustrates the diversity of topics that has resulted from the application of data from these networks.
Maternal and neonatal mortality is high in Africa, but few large, prospective studies have been done to investigate the risk factors associated with these poor maternal and neonatal outcomes.
A ...7-day, international, prospective, observational cohort study was done in patients having caesarean delivery in 183 hospitals across 22 countries in Africa. The inclusion criteria were all consecutive patients (aged ≥18 years) admitted to participating centres having elective and non-elective caesarean delivery during the 7-day study cohort period. To ensure a representative sample, each hospital had to provide data for 90% of the eligible patients during the recruitment week. The primary outcome was in-hospital maternal mortality and complications, which were assessed by local investigators. The study was registered on the South African National Health Research Database, number KZ_2015RP7_22, and on ClinicalTrials.gov, number NCT03044899.
Between February, 2016, and May, 2016, 3792 patients were recruited from hospitals across Africa. 3685 were included in the postoperative complications analysis (107 missing data) and 3684 were included in the maternal mortality analysis (108 missing data). These hospitals had a combined number of specialist surgeons, obstetricians, and anaesthetists totalling 0·7 per 100 000 population (IQR 0·2–2·0). Maternal mortality was 20 (0·5%) of 3684 patients (95% CI 0·3–0·8). Complications occurred in 633 (17·4%) of 3636 mothers (16·2–18·6), which were predominantly severe intraoperative and postoperative bleeding (136 3·8% of 3612 mothers). Maternal mortality was independently associated with a preoperative presentation of placenta praevia, placental abruption, ruptured uterus, antepartum haemorrhage (odds ratio 4·47 95% CI 1·46–13·65), and perioperative severe obstetric haemorrhage (5·87 1·99–17·34) or anaesthesia complications (11·47 (1·20–109·20). Neonatal mortality was 153 (4·4%) of 3506 infants (95% CI 3·7–5·0).
Maternal mortality after caesarean delivery in Africa is 50 times higher than that of high-income countries and is driven by peripartum haemorrhage and anaesthesia complications. Neonatal mortality is double the global average. Early identification and appropriate management of mothers at risk of peripartum haemorrhage might improve maternal and neonatal outcomes in Africa.
Medical Research Council of South Africa.
•An ensemble of partitioning methods are presented including stable carbon isotopes.•We paired ecosystem-scale fluxes of carbon isotopes with a biophysical model CANVEG.•Isotope-partitioned fluxes ...were 10–13% lower than standard-partitioned fluxes.•Differences among partitioning methods have implications for constraining models.
The partitioning of net ecosystem exchange of CO2 (NEE) into photosynthesis and respiration can be challenging and is often associated with assumptions that yield unknown amounts of uncertainty, thereby hindering model development. This occurs because we are inferring two pieces of information from one equation and measurement, NEE. While there are multiple methods for partitioning NEE, each has unique limitations that are difficult to evaluate as these techniques are often not implemented simultaneously. Here we present an analysis of multiple partitioning methods (a non-linear regression model known as the Reichstein method, artificial neural networks (ANN), stable carbon isotopes, and soil respiration (Rsoil) measurements) under ideal field conditions. We measured ecosystem-scale fluxes of stable C isotopes via a new quantum cascade laser (QCL) spectrometer and paired those measurements with a biophysical model CANVEG in order to close a system of equations and solve for gross primary productivity (GPP) and ecosystem respiration (Reco). Isotope-partitioned GPP and Reco were on average 10–13% lower than Reichstein- and ANN-partitioned GPP and Reco. These results suggest that the Reichstein and ANN approaches, which use nighttime NEE to infer daytime Reco, may be overestimating Reco and GPP during the day. This may be attributed to higher plant respiration rates at night compared to the day, otherwise known as the Kok effect. As isotope measurements and theory become more accessible to diverse ecosystems it will grow to be more than a benchmarking technique and into a valuable means of improving understanding of carbon cycling. Future studies are encouraged to evaluate these techniques in increasingly complex ecosystems to determine when significant differences appear between partitioning methods and how those differences influence modeling of terrestrial carbon budgets.
Disappointing survival rates from out-of-hospital cardiac arrests encourage strategies for faster defibrillation, such as use of automated external defibrillators (AEDs) by nonconventional ...responders.
AEDs were provided to all Miami-Dade County, Florida, police. AED-equipped police (P-AED) and conventional emergency medical rescue (EMS) responders are simultaneously deployed to possible cardiac arrests. Times from 9-1-1 contact to the scene were compared for P-AED and concurrently deployed EMS, and both were compared with historical EMS experience. Survival with P-AED was compared with outcomes when EMS was the sole responder. Among 420 paired dispatches of P-AED and EMS, the mean+/-SD P-AED time from 9-1-1 call to arrival at the scene was 6.16+/-4.27 minutes, compared with 7.56+/-3.60 minutes for EMS (P<0.001). Police arrived first to 56% of the calls. The time to first responder arrival among P-AED and EMS was 4.88+/-2.88 minutes (P<0.001), compared with a historical response time of 7.64+/-3.66 minutes when EMS was the sole responder. A 17.2% survival rate was observed for victims with ventricular fibrillation or pulseless ventricular tachycardia (VT/VF), compared with 9.0% for standard EMS before P-AED implementation (P=0.047). However, VT/VF benefit was diluted by the observation that 61% of the initial rhythms were nonshockable, reducing the absolute survival benefit among the total study population to 1.6% (P-AED, 7.6%; EMS, 6.0%).
P-AED establishes a layer of responders that generate improved response times and survival from VT/VF. There was no benefit for victims with nonshockable rhythms.
Measurements of hyperspectral canopy reflectance provide a detailed snapshot of information regarding canopy biochemistry, structure and physiology. In this study, we collected 5 years of repeated ...canopy hyperspectral reflectance measurements for a total of over 100 site visits within the flux footprints of two eddy covariance towers at a pasture and rice paddy in northern California. The vegetation at both sites exhibited dynamic phenology, with significant interannual variability in the timing of seasonal patterns that propagated into interannual variability in measured hyperspectral reflectance. We used partial least-squares regression (PLSR) modeling to leverage the information contained within the entire canopy reflectance spectra (400-900 nm) in order to investigate questions regarding the connection between measured hyperspectral reflectance and landscape-scale fluxes of net ecosystem exchange (NEE) and gross primary productivity (GPP) across multiple timescales, from instantaneous flux to monthly integrated flux. With the PLSR models developed from this large data set we achieved a high level of predictability for both NEE and GPP flux in these two ecosystems, where the R.sup.2 of prediction with an independent validation data set ranged from 0.24 to 0.69. The PLSR models achieved the highest skill at predicting the integrated GPP flux for the week prior to the hyperspectral canopy reflectance collection, whereas the NEE flux often achieved the same high predictive power at daily to monthly integrated flux timescales. The high level of predictability achieved by PLSR in this study demonstrated the potential for using repeated hyperspectral canopy reflectance measurements to help partition NEE into its component fluxes, GPP and ecosystem respiration, and for using quasi-continuous hyperspectral reflectance measurements to model regional carbon flux in future analyses.
Measurements of hyperspectral canopy reflectance provide a detailed snapshot of information regarding canopy biochemistry, structure and physiology. In this study, we collected 5 years of repeated ...canopy hyperspectral reflectance measurements for a total of over 100 site visits within the flux footprints of two eddy covariance towers at a pasture and rice paddy in northern California. The vegetation at both sites exhibited dynamic phenology, with significant interannual variability in the timing of seasonal patterns that propagated into interannual variability in measured hyperspectral reflectance. We used partial least-squares regression (PLSR) modeling to leverage the information contained within the entire canopy reflectance spectra (400–900 nm) in order to investigate questions regarding the connection between measured hyperspectral reflectance and landscape-scale fluxes of net ecosystem exchange (NEE) and gross primary productivity (GPP) across multiple timescales, from instantaneous flux to monthly integrated flux. With the PLSR models developed from this large data set we achieved a high level of predictability for both NEE and GPP flux in these two ecosystems, where the R2 of prediction with an independent validation data set ranged from 0.24 to 0.69. The PLSR models achieved the highest skill at predicting the integrated GPP flux for the week prior to the hyperspectral canopy reflectance collection, whereas the NEE flux often achieved the same high predictive power at daily to monthly integrated flux timescales. The high level of predictability achieved by PLSR in this study demonstrated the potential for using repeated hyperspectral canopy reflectance measurements to help partition NEE into its component fluxes, GPP and ecosystem respiration, and for using quasi-continuous hyperspectral reflectance measurements to model regional carbon flux in future analyses.
The Sudbury Neutrino Observatory Boger, J; Hahn, R.L; Rowley, J.K ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2000, Letnik:
449, Številka:
1
Journal Article
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The Sudbury Neutrino Observatory is a second-generation water Cherenkov detector designed to determine whether the currently observed solar neutrino deficit is a result of neutrino oscillations. The ...detector is unique in its use of D
2O as a detection medium, permitting it to make a solar model-independent test of the neutrino oscillation hypothesis by comparison of the charged- and neutral-current interaction rates. In this paper the physical properties, construction, and preliminary operation of the Sudbury Neutrino Observatory are described. Data and predicted operating parameters are provided whenever possible.
Extensive research, involving a large programme of both experimental and numerical analyses, has been undertaken into the structural integrity of adhesively bonded GRE composite taper/taper pipe ...joints. Initial studies investigated the short-term static performance under various modes of loading and these were followed by studies of long-term creep performance. A significant element of the research was a study of the effect that defects in the adhesive bond have on the overall performance of the bonded joint-pipe system. The numerical analyses were correlated with the experimental data for validation of the computer simulations and failure predictions. The results of the research demonstrate the substantial defect tolerance of the bonded composite components. From the results it is possible to present guidelines for residual strength, deflection and the effects of defect size, as a function of pipe diameter, temperature and time. Such guidelines may be used at the initial design stage or to inform inspection and repair strategies.
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