Linking mineralisation process and sedimentary product in terrestrial carbonates using a solution thermodynamic approach

Determining the processes which generate terrestrial carbonate deposits (tufas, travertines and to a lesser extent associated chemical sediments such as calcretes and speleothems) is a long-standing problem. Precipitation of mineral products from solution reflects a complex combination of biological, equilibrium and kinetic processes, and the different morphologies of carbonate sediment produced by different processes have yet to be clearly demarked. Building on the groundbreaking work of previous authors, we propose that the underlying control on the processes leading to the deposition of these products can be most parsimoniously understood from the thermodynamic properties of their source solutions. Here, we report initial observations of the differences in product generated from spring and lake systems spanning a range of temperature–supersaturation space. We find that at high supersaturation, biological influences are masked by high rates of physico-chemical precipitation, and sedimentary products from these settings infrequently exhibit classic "biomediated" fabrics such as clotted micrite. Likewise, at high temperature (>40 °C) exclusion of vascular plants and complex/diverse biofilms can significantly inhibit the magnitude of biomediated precipitation, again impeding the likelihood of encountering the "bio-type" fabrics. <br></br> Conversely, despite the clear division in product between extensive tufa facies associations and less spatially extensive deposits such as oncoid beds, no clear division can be identified between these systems in temperature–supersaturation space. We reiterate the conclusion of previous authors, which demonstrate that this division cannot be made on the basis of physico-chemical characteristics of the solution alone. We further provide a new case study of this division from two adjacent systems in the UK, where tufa-like deposition continuous on a metre scale is happening at a site with lower supersaturation than other sites exhibiting only discontinuous (oncoidal) deposition. However, a strong microbiological division is demonstrated between these sites on the basis of suspended bacterial cell distribution, which reach a prominent maximum where tufa-like deposits are forming. <br></br> We conclude that at high supersaturation, the thermodynamic properties of solutions provide a highly satisfactory means of linking process and product, raising the opportunity of identifying water characteristics from sedimentological/petrological characteristics of ancient deposits. At low supersaturation, we recommend that future research focuses on geomicrobiological processes rather than the more traditional, inorganic solution chemistry approach dominant in the past

Validation of the CREST score for predicting circulatory-aetiology death in out-of-hospital cardiac arrest without STEMI

Aims: The CREST tool was recently developed to stratify the risk of circulatory-aetiology death (CED) in out-of-hospital cardiac arrest (OHCA) patients without ST-elevation myocardial infarction (STEMI). We aimed to validate the CREST score using an external cohort and determine whether it could be improved by the addition of serum lactate on admission. Methods: The study involved the retrospective analysis of consecutive patients admitted to a single tertiary centre with OHCA of presumed cardiac origin over a 51-month period. The CREST score was calculated by attributing points to the following variables: Coronary artery disease (CAD), non-shockable Rhythm, Ejection fraction <30%, cardiogenic Shock at presentation and ischaemic Time ≥25 minutes. The primary endpoint was CED vs neurological aetiology death (NED) or survival. Results: Of 500 patients admitted with OHCA, 211 did not meet criteria for STEMI and were included. 115 patients died in hospital (71 NED, 44 CED). When analysed individually, CED was associated with all CREST variables other than a previous diagnosis of CAD. The CREST score accurately predicted CED with excellent discrimination (C-statistic 0.880, 95% CI 0.813-0.946) and calibration (Hosmer and Lemeshow P=0.948). Although an admission lactate ≥7 mmol/L also predicted CED, its addition to the CREST score (the C-AREST score) did not significantly improve the predictive ability (CS 0.885, 0.815-0.954, HS P=0.942, X2 difference in -2 log likelihood =0.326, P=0.850). Conclusion: Our study is the first to independently validate the CREST score for predicting CED in patients presenting with OHCA without STEMI. Addition of lactate on admission did not improve its predictive ability.Publisher PDFPeer reviewe

Use of mechanical circulatory support in patients with non-ischaemic cardiogenic shock

Aims Despite its high incidence and mortality risk, there is no evidence-based treatment for non-ischaemic cardiogenic shock (CS). The aim of this study was to evaluate the use of mechanical circulatory support (MCS) for non-ischaemic CS treatment.Methods and results In this multicentre, international, retrospective study, data from 890 patients with non-ischaemic CS, defined as CS due to severe de-novo or acute-on-chronic heart failure with no need for urgent revascularization, treated with or without active MCS, were collected. The association between active MCS use and the primary endpoint of 30-day mortality was assessed in a 1:1 propensity-matched cohort. MCS was used in 386 (43%) patients. Patients treated with MCS presented with more severe CS (37% vs. 23% deteriorating CS, 30% vs. 25% in extremis CS) and had a lower left ventricular ejection fraction at baseline (21% vs. 25%). After matching, 267 patients treated with MCS were compared with 267 patients treated without MCS. In the matched cohort, MCS use was associated with a lower 30-day mortality (hazard ratio 0.76, 95% confidence interval 0.59-0.97). This finding was consistent through all tested subgroups except when CS severity was considered, indicating risk reduction especially in patients with deteriorating CS. However, complications occurred more frequently in patients with MCS; e.g. severe bleeding (16.5% vs. 6.4%) and access-site related ischaemia (6.7% vs. 0%).Conclusion In patients with non-ischaemic CS, MCS use was associated with lower 30-day mortality as compared to medical therapy only, but also with more complications. Randomized trials are needed to validate these findings.[GRAPHICS

Avaliação do uso de resíduo de serragem de pedra Cariri (RSPC) para produção de concretos convencionais

No estado do Ceará, na região do Cariri, um minério calcário laminado, comercialmente conhecido como pedra Cariri, é muito explorado. Os processos de exploração e beneficiamento desse minério são causas da geração de resíduos. Um dos tipos de resíduo gerado é o decorrente da serragem de pedra Cariri, denominado de resíduo de serragem de pedra Cariri (RSPC). Nesta pesquisa, avalia-se a viabilidade do uso de RSPC como substituição parcial do cimento na produção de concretos convencionais. Foram determinadas as características químicas e físicas do RSPC. A influência foi avaliada através das propriedades mecânicas (resistência à compressão axial e diametral) e parâmetros de durabilidade (absorção por imersão e por sucção capilar). Foram produzidos 9 traços, variando a relação a/c (0,45; 0,55; 0,65) e os teores de substituição (0%, 10% e 20%) do cimento. Os resultados demonstram que a utilização de RSPC no concreto proporcionou uma redução nas resistências à compressão e à tração por compressão diametral. Entretanto, em relação aos parâmetros de durabilidade, os concretos com RSPC apresentaram comportamento compatível com os concretos de referência. De um modo geral, do ponto de vista técnico, o RSPC não proporcionou resultados satisfatórios para aplicação em concreto

Lateglacial and Holocene relative sea-level changes and first evidence for the Storegga tsunami in Sutherland, Scotland

We reconstruct one of the longest relative sea-level (RSL) records in northwest Europe from the north coast of mainland Scotland, using data collected from three sites in Loch Eriboll (Sutherland) that we combine with other studies from the region. Following deglaciation, RSL fell from a Late Glacial highstand of +6-8 m OD (Ordnance Datum = c. mean sea level) at c. 15 k cal a BP to below present, then rose to an early Holocene highstand and remained at c. +1 m OD between c. 7 and 3 k cal a BP, before falling to present. We find no evidence for significant differential Holocene glacio-isostatic adjustment between sites on the northwest (Lochinver, Loch Laxford), north (Loch Eriboll) and northeast (Wick) coast of mainland Scotland. This suggests that the region was rapidly deglaciated and there was little difference in ice loads across the region. From one site at the head of Loch Eriboll we report the most westerly sedimentary evidence for the early Holocene Storegga tsunami on the Scottish mainland. The presence of the Storegga tsunami in Loch Eriboll is predicted by a tsunami wave model, which suggests that the tsunami impacted the entire north coast of Scotland and likely also the Atlantic coastline of northwest Scotland

An observational study assessing the impact of a cardiac arrest centre on patient outcome

Abstract P2665 from ESC Congress 2019 together with World Congress of Cardiology 31 August – 4 September 2019, Paris - Franc