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Canonical isomorphisms of determinant line bundles
No full textWe prove that the Adams–Riemann–Roch theorem in degree one (i.e., at the level of the Picard group) can be lifted to an isomorphism of line bundles, compatibly with base change
Chronic airflow obstruction and ambient particulate air pollution
No full textSmoking is the most well-established cause of chronic airflow obstruction (CAO) but particulate air pollution and poverty have also been implicated. We regressed sex-specific prevalence of CAO from 41 Burden of Obstructive Lung Disease study sites against smoking prevalence from the same study, the gross national income per capita and the local annual mean level of ambient particulate matter (PM2.5) using negative binomial regression. The prevalence of CAO was not independently associated with PM2.5 but was strongly associated with smoking and was also associated with poverty. Strengthening tobacco control and improved understanding of the link between CAO and poverty should be prioritised
Analysis of contagion maps on a class of networks that are spatially embedded in a torus
No full textSpreading processes on networks with some underlying spatial structure can be influenced by that structure, and it is insightful to study the extent to which a spreading process follows a network's underlying geometry. We consider a threshold contagion model on networks whose nodes are embedded in a manifold and which have both “geometric edges,” which respect the geometry of the underlying manifold, and “nongeometric edges,” which are not constrained by that geometry. Building on ideas from Taylor et al. [Nat. Commun., 6 (2015), 7723], we examine when a contagion propagates as a wave along a network whose nodes are embedded in a torus and when it jumps via long nongeometric edges to remote areas of the network. We build a “contagion map” for a contagion spreading on such a “noisy geometric network” to produce a point cloud, and we study the dimensionality, geometry, and topology of this point cloud to examine qualitative properties of this spreading process. We identify a region in parameter space in which the contagion propagates predominantly via wavefront propagation. We consider different probability distributions for constructing nongeometric edges---reflecting different decay rates with respect to the distance between nodes in the underlying manifold---and examine the effect of such choices on the qualitative properties of the spreading dynamics. Our work generalizes the analysis in Taylor et al. [Nat. Commun., 6 (2015), 7723] and consolidates contagion maps both as a tool for investigating spreading behavior on spatial networks and as a technique for manifold learning
Complex interventions to implement a diabetic retinopathy care pathway in the public health system in Kerala: The Nayanamritham study protocol
No full textIntroduction:
Using a type 2 hybrid effectiveness-implementation design, we aim to pilot a diabetic retinopathy (DR) care pathway in the public health system in Kerala to understand how it can be scaled up to and sustained in the whole state.
Methods and analysis:
Currently, there is no systematic DR screening programme in Kerala. Our intervention is a teleophthalmology pathway for people with diabetes in the non-communicable disease registers in 16 family health centres. The planned implementation strategy of the pathway will be developed based on the discrete Expert Recommendations for Implementing Change taxonomy. We will use both quantitative data from a cross-sectional study and qualitative data obtained from structured interviews, surveys and group discussions with stakeholders to report the effectiveness of the DR care pathway and evaluation of the implementation strategy.
We will use logistic regression models to assess crude associations DR and sight-threatening diabetic retinopathy and fractional polynomials to account for the form of continuous covariates to predict uptake of DR screening. The primary effectiveness outcome is the proportion of patients in the non-communicable disease register with diabetes screened for DR over 12 months. Other outcomes include cost-effectiveness, safety, efficiency, patient satisfaction, timeliness and equity. The outcomes of evaluation of the implementation strategies include acceptability, feasibility, adoption, appropriateness, fidelity, penetration, costs and sustainability. Addition of more family health centres during the staggered initial phase of the programme will be considered as a sign of acceptability and feasibility. In the long term, the state-wide adoption of the DR care pathway will be considered as a successful outcome of the Nayanamritham study.
Ethics and dissemination:
The study was approved by Indian Medical Research Council (2018-0551) dated 13 March 2019. Study findings will be disseminated through scientific publications and the report will inform adoption of the DR care pathway by Kerala state in future.
Trial registration number: ISRCTN28942696
A global environmental crisis 42,000 years ago
No full textGeological archives record multiple reversals of Earth's magnetic poles, but the global impacts of these events, if any, remain unclear. Uncertain radiocarbon calibration has limited investigation of the potential effects of the last major magnetic inversion, known as the Laschamps Excursion [41 to 42 thousand years ago (ka)]. We use ancient New Zealand kauri trees (Agathis australis) to develop a detailed record of atmospheric radiocarbon levels across the Laschamps Excursion. We precisely characterize the geomagnetic reversal and perform global chemistry-climate modeling and detailed radiocarbon dating of paleoenvironmental records to investigate impacts. We find that geomagnetic field minima ~42 ka, in combination with Grand Solar Minima, caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record
Fluid flows on many scales
No full textA single equation can describe how fluids flow across a wide range of length scales, from ocean currents to swimming algae. The difference merely lies in the Reynolds number, says Julia Yeomans
Characterizing regimes of atmospheric circulation in terms of their global superrotation
No full textThe global superrotation index S compares the integrated axial angular momentum of the atmosphere to that of a state of solid-body corotation with the underlying planet. The index S is similar to a zonal Rossby number, which suggests it may be a useful indicator of the circulation regime occupied by a planetary atmosphere. We investigate the utility of S for characterizing regimes of atmospheric circulation by running idealized Earthlike general circulation model experiments over a wide range of rotation rates Ω, 8ΩE to ΩE/512, where ΩE is Earth’s rotation rate, in both an axisymmetric and three-dimensional configuration. We compute S for each simulated circulation, and study the dependence of S on Ω. For all rotation rates considered, S is on the same order of magnitude in the 3D and axisymmetric experiments. For high rotation rates, S ≪ 1 and S ∝ Ω−2, while at low rotation rates S ≈ 1/2 = constant. By considering the limiting behavior of theoretical models for S, we show how the value of S and its local dependence on Ω can be related to the circulation regime occupied by a planetary atmosphere. Indices of S ≪ 1 and S ∝ Ω−2 define a regime dominated by geostrophic thermal wind balance, and S ≈ 1/2 = constant defines a regime where the dynamics are characterized by conservation of angular momentum within a planetary-scale Hadley circulation. Indices of S ≫ 1 and S ∝ Ω−2 define an additional regime dominated by cyclostrophic balance and strong equatorial superrotation that is not realized in our simulations
ELBW and ELGAN outcomes in developing nations – systematic review and meta-analysis
No full textContext
Morbidity and mortality amongst extremely low birth weight (ELBW) and extremely low gestational age neonates (ELGANs) in developing nations has not been well studied.
Objectives
Evaluate survival until discharge, short- and long-term morbidities of ELBW and ELGANs in LMICs.
Data sources
CENTRAL, EMBASE, MEDLINE and Web of Science.
Study selection
Prospective and retrospective observational studies were included.
Data extraction and synthesis
Four authors extracted data independently. Random-effects meta-analysis of proportions was used to synthesize data, modified QUIPS scale to evaluate quality of studies and GRADE approach to ascertain the certainty of evidence (CoE).
Results
192 studies enrolling 22,278 ELBW and 18,338 ELGANs were included. Survival was 34% (95% CI: 31% - 37%) (CoE–low) for ELBW and 39% (34% - 44%) (CoE—moderate) for ELGANs. For ELBW neonates, the survival for low-income (LI), lower middle-income (LMI) and upper middle income (UMI) countries was 18% (11% - 28%), 28% (21% - 35%) and 39% (36% - 42%), respectively. For ELGANs, it was 13% (8% - 20%) for LI, 28% (21% - 36%) for LMI and 48% (42% - 53%) for UMI countries. There was no difference in survival between two epochs: 2000–2009 and 2010–2020. Except for necrotising enterocolitis [ELBW and ELGANs—8% (7% - 10%)] and periventricular leukomalacia [ELBW—7% (4% - 11%); ELGANs—6% (5%-7%)], rates of all other morbidities were higher compared to developed nations. Rates of neurodevelopmental impairment was 17% (7% - 34%) in ELBW neonates and 29% (23% - 37%) in ELGANs.
Limitations
CoE was very low to low for all secondary outcomes.
Conclusions
Mortality and morbidity amongst ELBW and ELGANs is still a significant burden in LMICs. CoE was very low to low for all the secondary outcomes, emphasizing the need for high quality prospective cohort studies.
Trial registration
PROSPERO (CRD42020222873)
Continuity in κ in SLEκ theory using a constructive method and rough path theory
No full textQuestions regarding the continuity in κ of the SLEκ traces and maps appear very naturally in the study of SLE. In order to study the first question, we consider a natural coupling of SLE traces: for different values of κ we use the same Brownian motion. It is very natural to assume that with probability one, SLEκ depends continuously on κ. It is rather easy to show that SLE is continuous in the Carath´eodory sense, but showing that SLE traces are continuous in the uniform sense is much harder. In this note we show that for a given sequence κj → κ ∈ (0, 8/3), for almost every Brownian motion SLEκ traces converge locally uniformly. This result was also recently obtained by Friz, Tran and Yuan using different methods. In our analysis, we provide a constructive way to study the SLEκ traces for varying parameter κ ∈ (0, 8/3). The argument is based on a new dynamical view on the approximation of SLE curves by curves driven by a piecewise square root approximation of the Brownian motion. The second question can be answered naturally in the framework of Rough Path Theory. Using this theory, we prove that the solutions of the backward Loewner Differential Equation driven by √κBt when started away from the origin are continuous in the p-variation topology in the parameter κ, for all κ ∈ R+
Characterisation of the T-cell response to Ebola virus glycoprotein amongst survivors of the 2013-16 West Africa epidemic
No full textEbolavirus is a highly pathogenic filovirus which can result in Ebolavirus disease, a serious medical condition that presents itself as flu like symptoms but then often leads to more serious or fatal outcomes. The 2014-16 West Africa outbreak saw an unparalleled number of cases and we have been able to work with survivor associations within Guinea to sample peripheral blood and look at the long-term T cell response to stimulation with Ebolavirus glycoprotein. We performed IFNy ELISpot using a glycoprotein peptide library to identify novel epitopes, we then tested these to look for either a CD4+ or CD8+ T cell response by flow cytometry, additionally, we generated data on the T cell phenotype and measured polyfunctional cytokine secretion by antigen specific cells. We found a number of candidate peptides that were able to elicit a T cell response in survivors, furthermore, we were able to match these to specific HLA types and infer HLA allele restriction. This data informs on the long-term T cell response to Ebola virus disease and highlights potentially important immunodominant peptides