Network meta-analysis of diagnostic test accuracy studies identifies and ranks the optimal diagnostic tests and thresholds for healthcare policy and decision making

Objective: Network meta-analyses have extensively been used to compare the effectiveness of multiple interventions for healthcare policy and decision-making. However, methods for evaluating the performance of multiple diagnostic tests are less established. In a decision-making context, we are often interested in comparing and ranking the performance of multiple diagnostic tests, at varying levels of test thresholds, in one simultaneous analysis. Study design and setting: Motivated by an example of cognitive impairment diagnosis following stroke, we synthesized data from 13 studies assessing the efficiency of two diagnostic tests: Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA), at two test thresholds: MMSE <25/30 and <27/30, and MoCA <22/30 and <26/30. Using Markov Chain Monte Carlo (MCMC) methods, we fitted a bivariate network meta-analysis model incorporating constraints on increasing test threshold, and accounting for the correlations between multiple test accuracy measures from the same study. Results: We developed and successfully fitted a model comparing multiple tests/threshold combinations while imposing threshold constraints. Using this model, we found that MoCA at threshold <26/30 appeared to have the best true positive rate, whilst MMSE at threshold <25/30 appeared to have the best true negative rate. Conclusion: The combined analysis of multiple tests at multiple thresholds allowed for more rigorous comparisons between competing diagnostics tests for decision making

Projecting the Hydrological and Geochemical Evolution of a Constructed Fen Watershed in the Athabasca Oil Sands Region, Alberta, Canada

Ongoing commercial bitumen surface mining operations have fundamentally altered large areas of forested uplands and fen peatlands in the Athabasca Oil Sands Region (AOSR), Alberta, Canada. Returning fen peatland functions that are representative of the pre-disturbance state has become a matter of increasing public interest, and has been adopted into the regulatory framework. Prompted by the prevalence of fens on the undisturbed landscape, this regulatory framework has recently mandated the trial of fen peatland reclamation at the pilot-scale to assess the viability of including these ecosystems in mine closure planning. It was hypothesized that the creation of a surrogate fen that exhibited many of the same functional traits as a natural system could be accomplished by providing a reasonable approximation of the hydrogeologic setting of peatlands characteristic to the region. This principle guided the conceptual design of the Nikanotee Fen Watershed, one of the pioneering experimental watersheds built on the post-mined landscape. The design of this pilot project incorporated an upland aquifer capable of supplying the peatland with a consistent source of water. Construction of the site was completed in January 2013, and used a combination of salvaged, process-affected, and engineered materials. Residual concentrations of sodium and other solutes imparted to the coarse tailings sand aquifer material during the bitumen extraction process, introduced the potential for rooting zone salinization that could negatively impact fen vegetation. Initial assessments of the Nikanotee Fen Watershed demonstrated that in the early post-construction period the site was functioning in accordance with the design. However, meaningful changes in the function of the system will occur as the site matures due to soil evolution, vegetation development, and the progressive transport of solutes from the upland to the fen. The timeline that these processes will evolve on preclude purely observational research and require the use of techniques that can project hydrologic behaviour into the future as the site matures. Generating information on the future efficacy of the Nikanotee Fen Watershed will be crucial to informing mine operators and reclamation planners of the viability of fen reclamation. Assessing the probable trajectory of the upland and fen was accomplished using field data, laboratory experiments, and numerical modelling. The impact of the evolving upland in the short-term (due to soil weathering) and the long-term (due to vegetation development) was investigated with soil moisture dynamics modelling. Next, a thorough characterization of the hydraulic properties that influence the fate and transport of sodium from the tailings sand aquifer was conducted with a field-scale tracer test, and laboratory experiments. Finally, the likely developmental pathway of the fen was evaluated by integrating information from the previous research into a groundwater flow and solute transport model of the watershed. These studies have (1) illustrated the impact of weathering on the soil hydraulic properties and water balance fluxes of cover soils in the early post-construction period; (2) demonstrated the value of snowmelt for recharging groundwater in the reclaimed uplands and improved the understanding of the relationship between cover soil systems and vegetation growth; (3) identified the hydraulic and transport properties of coarse tailings sand – a material that will be ubiquitous on the closure landscape; and (4) provided a novel evaluation of the hydrochemical trajectory of a constructed peatland watershed with respect to water availability and sodium concentrations, which upheld the original conceptual design, and strongly suggested that the system will continue to support fen ecohydrological function. This research represents one of the first comprehensive attempts to illuminate the probable developmental pathway of a fen reclamation pilot project in a post-mined landscape. The Nikanotee Fen Watershed has accomplished many of its epistemic goals associated with the generation of research and operational knowledge, and ultimately, appears poised to replicate fen ecohydrological function into the future by successfully regulating the limited available moisture, and managing the salinity from process-affected materials

Numerical calculation of strong-field laser-atom interaction: An approach with perfect reflection-free radiation boundary conditions

The time-dependent, single-particle Schrodinger equation with a finite-range potential is solved numerically on a three-dimensional spherical domain. In order to correctly account for outgoing waves, perfect reflection-free radiation boundary conditions are used on the surface of a sphere. These are computationally most effective if the particle wavefunction is expanded in the set of spherical harmonics and computations are performed in the Kramers-Henneberger accelerated frame. The method allows one to solve the full ionization dynamics in intense laser fields within a small region of atomic dimensions

Metrology for Ammonia in Ambient Air – concept and first results of the EMRP project MetNH3

Dans le cadre du Programme de Recherche Européen en Métrologie (EMRP), un projet de trois ans a débuté en juin 2014 avec l’objectif d’améliorer la compréhension et la traçabilité métrologique des mesures d’ammoniac (NH3) ambient, dans le domaine 0.5 - 500 nmol/mol. Les trois tâches principales de ce projet sont 1) d’améliorer l’exactitude et la stabilité de mélanges de gaz de référence statiques et dynamiques, 2) de développer un étalon de transfert optique et 3) d’établir un lien entre les standards métrologiques de haute précision et les mesures de terrain. Les résultats attendus de ce projet vont améliorer l’exactitude et la fiabilité des estimations d’émissions et ainsi aider à l’évaluation de l’efficacité des mesures de réduction d’émission prescrites par les réglementations internationales. Dans cette publication nous décrivons le concept, les objectifs et les premiers résultats du projet

Preferential recharge in a reclaimed tailings sand upland: Implications on solute flushing

Study region: A peatland watershed was constructed on a post-mined oil sands lease in Northern Alberta, Canada, with the intention of replicating the function of natural wetlands removed by surface mining. Study focus: Given the potential for moisture limited conditions due to the sub-humid regional climate, ensuring sufficient water availability in these landscapes is a principal concern. This research demonstrates how small recharge basins can modify the hydrology to promote groundwater recharge critical for sustaining saturated conditions in a downgradient wetland. New hydrological insights for the region: Location was important in determining the efficacy of recharge basins. Specifically, basins placed at the confluence of two hillslopes detained substantial volumes of runoff due to large upslope areas, contributing ~30% of the groundwater budget to the fen, while only occupying 1% of the upland area. Basins situated near low relief hillslopes or altogether isolated from a hillslope did not detain appreciable runoff and therefore had a minor role in recharging groundwater. Groundwater in the vicinity and downgradient of active recharge basins had considerably lower solute concentrations because of dilution. This suggests that basins can not only enhance recharge within engineered landscapes, providing a consistent and focused supply of water to upland aquifers, but offer relatively fresh groundwater to downgradient ecosystems. This could ameliorate the impact of high salinity present in oil sands process-affected materials.Natural Sciences and Engineering Research Council of Canad

Etiology and epidemiology of Pythium root rot in hydroponic crops: current knowledge and perspectives.

The etiology and epidemiology of Pythium root rot in hydroponically-grown crops are reviewed with emphasis on knowledge and concepts considered important for managing the disease in commercial greenhouses. Pythium root rot continually threatens the productivity of numerous kinds of crops in hydroponic systems around the world including cucumber, tomato, sweet pepper, spinach, lettuce, nasturtium, arugula, rose, and chrysanthemum. Principal causal agents include Pythium aphanidermatum, Pythium dissotocum, members of Pythium group F, and Pythium ultimum var. ultimum. Perspectives are given of sources of initial inoculum of Pythium spp. in hydroponic systems, of infection and colonization of roots by the pathogens, symptom development and inoculum production in host roots, and inoculum dispersal in nutrient solutions. Recent findings that a specific elicitor produced by P. aphanidermatum may trigger necrosis (browning) of the roots and the transition from biotrophic to necrotrophic infection are considered. Effects on root rot epidemics of host factors (disease susceptibility, phenological growth stage, root exudates and phenolic substances), the root environment (rooting media, concentrations of dissolved oxygen and phenolic substances in the nutrient solution, microbial communities and temperature) and human interferences (cropping practices and control measures) are reviewed. Recent findings on predisposition of roots to Pythium attack by environmental stress factors are highlighted. The commonly minor impact on epidemics of measures to disinfest nutrient solution as it recirculates outside the crop is contrasted with the impact of treatments that suppress Pythium in the roots and root zone of the crop. New discoveries that infection of roots by P. aphanidermatum markedly slows the increase in leaf area and whole-plant carbon gain without significant effect on the efficiency of photosynthesis per unit area of leaf are noted. The platform of knowledge and understanding of the etiology and epidemiology of root rot, and its effects on the physiology of the whole plant, are discussed in relation to new research directions and development of better practices to manage the disease in hydroponic crops. Focus is on methods and technologies for tracking Pythium and root rot, and on developing, integrating, and optimizing treatments to suppress the pathogen in the root zone and progress of root rot.Revisão

Epidemiology of musculoskeletal injury in military recruits: A systematic review and meta-analysis

Background: Injuries are a common occurrence in military recruit training, however due to differences in the capture of training exposure, injury incidence rates are rarely reported. Our aim was to determine the musculoskeletal injury epidemiology of military recruits, including a standardised injury incidence rate. Methods: Epidemiological systematic review following the PRISMA 2020 guidelines. Five online databases were searched from database inception to 5th May 2021. Prospective and retrospective studies that reported data on musculoskeletal injuries sustained by military recruits after the year 2000 were included. We reported on the frequency, prevalence and injury incidence rate. Incidence rate per 1000 training days (Exact 95% CI) was calculated using meta-analysis to allow comparisons between studies. Observed heterogeneity (e.g., training duration) precluded pooling of results across countries. The Joanna Briggs Institute Quality Assessment Checklist for Prevalence Studies assessed study quality. Results: This review identified 41 studies comprising 451,782 recruits. Most studies (n = 26; 63%) reported the number of injured recruits, and the majority of studies (n = 27; 66%) reported the number of injuries to recruits. The prevalence of recruits with medical attention injuries or time-loss injuries was 22.8% and 31.4%, respectively. Meta-analysis revealed the injury incidence rate for recruits with a medical attention injury may be as high as 19.52 injuries per 1000 training days; and time-loss injury may be as high as 3.97 injuries per 1000 training days. Longer recruit training programs were associated with a reduced injury incidence rate (p = 0.003). The overall certainty of the evidence was low per a modified GRADE approach. Conclusion: This systematic review with meta-analysis highlights a high musculoskeletal injury prevalence and injury incidence rate within military recruits undergoing basic training with minimal improvement observed over the past 20 years. Longer training program, which may decrease the degree of overload experienced by recruit, may reduce injury incidence rates. Unfortunately, reporting standards and reporting consistency remain a barrier to generalisability. Trial registration: PROSPERO (Registration number: CRD42021251080)

School-linked sexual health services for young people (SSHYP): a survey and systematic review concerning current models, effectiveness, cost-effectiveness and research opportunities

Background: Report based on a service-mapping study and a systematic review concerning sexual health services for young people, either based in or closely linked to schools. Objectives: To identify current forms of school-based sexual health services (SBSHS) and school-linked sexual health services (SLSHS) in the UK, review and synthesise existing evidence from qualitative and quantitative studies concerning the effectiveness, acceptability and cost-effectiveness of these types of service and to identify potential areas for further research. Data sources: Electronic databases were searched from 1985 onwards. For published material: the Cochrane Library (1991–), MEDLINE, PREMEDLINE (2007–), CINAHL, EMBASE, AMED, ASSIA (1987–), IBSS, ERIC, PsycINFO, Science Citation Index (SCI) and Social Sciences Citation Index. For unpublished material and grey literature: the Social Care Institute of Excellence Research Register; the National Research Register (1997–), ReFeR; Index to Theses, and HMIC. Review methods: A service-mapping questionnaire was circulated to school nurses in all parts of the UK, and semistructured telephone interviews with service coordinators in NHS and local authority (LA) roles were conducted. An evidence synthesis was performed based on a systematic review of the quantitative evidence about service effectiveness, qualitative evidence about user and professional views and a mixed-methods synthesis. A proof-of-concept model for assessing cost-effectiveness was drawn up. Results: Three broad types of UK sexual health service provision were identified. Firstly, SBSHS staffed by school nurses, offering ‘minimal’ or ‘basic’ levels of service. Secondly, SBSHS and SLSHS staffed by a multiprofessional team, but not medical practitioners, offering ‘basic’ or ‘intermediate’ levels of service. Thirdly, SBSHS and SLSHS staffed by a multiprofessional team, including medical practitioners offering ‘intermediate’ or ‘comprehensive’ levels of service. The systematic review showed that SBSHS are not associated with higher rates of sexual activity among young people, nor with an earlier age of first intercourse. There was evidence to show positive effects in terms of reductions in births to teenage mothers, and in chlamydial infection rates among young men, although this evidence coming primarily from the USA. Therefore, the findings need to be tested in relation to UK-based services. Also evidence to suggest that broad-based, holistic service models, not restricted to sexual health, offer the strongest basis for protecting young people’s privacy and confidentiality, countering perceived stigmatisation, offering the most comprehensive range of products and services, and maximising service uptake. Findings from the mapping study also indicate that broad-based services, which include medical practitioner input within a multiprofessional team, meet the stated preferences of staff and of young people most clearly. Partnership-based developments of this kind also conform to the broad policy principles embodied in the Every Child Matters framework in the UK and allied policy initiatives. However, neither these service models nor narrower ones have been rigorously evaluated in terms of their impact on the key outcomes of conception rates and sexually transmitted infection (STI) rates, in the UK or in other countries. Therefore, appropriate data were not found to support cost-effectiveness modelling. Limitations: Low response rate to the questionnaire. Scotland, Wales and Northern Ireland were under-represented. Also, the distinction made in the questionnaire between ‘general health’ and ‘sexual health’ services did not prove robust. Conclusions: There is no single, dominant service model in the UK. The systematic review demonstrated that the evidence base for these services remains limited and uneven, and draws largely on US studies. Qualitative research is needed to develop robust process and outcome indicators for the evaluation of SLSHS/SBSHS in the UK. These indicators could then be used both in local evaluations, and in large, longitudinal studies of service effectiveness and cost-effectiveness. Future research should examine the impact of the differing types of services currently evolving in the UK, encompassing school-based and school-linked models, as well as models with and without medical practitioner involvement

The World-Trade Web: Topological Properties, Dynamics, and Evolution

This paper studies the statistical properties of the web of import-export relationships among world countries using a weighted-network approach. We analyze how the distributions of the most important network statistics measuring connectivity, assortativity, clustering and centrality have co-evolved over time. We show that all node-statistic distributions and their correlation structure have remained surprisingly stable in the last 20 years -- and are likely to do so in the future. Conversely, the distribution of (positive) link weights is slowly moving from a log-normal density towards a power law. We also characterize the autoregressive properties of network-statistics dynamics. We find that network-statistics growth rates are well-proxied by fat-tailed densities like the Laplace or the asymmetric exponential-power. Finally, we find that all our results are reasonably robust to a few alternative, economically-meaningful, weighting schemes.Comment: 44 pages, 39 eps figure

Sample size assessments for thermal physiology studies: An R package and R Shiny application

Required sample sizes for a study need to be carefully assessed to account for logistics, cost, ethics and statistical rigour. For example, many studies have shown that methodological variations can impact the critical thermal limits (CTLs) recorded for a species, although studies on the impact of sample size on these measures are lacking. Here, we present ThermalSampleR; an R CRAN package and Shiny application that can assist researchers in determining when adequate sample sizes have been reached for their data. The method is particularly useful because it is not taxon specific. The Shiny application offers a user‐friendly interface equivalent to the package for users not familiar with R programming. ThermalSampleR is accompanied by an in‐built example dataset, which we use to guide the user through the workflow with a fully worked tutorial.Funder: National Research Foundation; doi: http://dx.doi.org/10.13039/501100001321 Funder: South African Research Chairs Initiative of the Department of Science and Technology Funder: Working for Water (WfW) programme of the Department of Environmental Affairs: Natural Resource Management programme (DEA: NRM