34 research outputs found
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.
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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.
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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
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 resÃduo 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 resÃduos. Um dos tipos de resÃduo gerado é o decorrente da serragem de pedra Cariri, denominado de resÃduo 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 caracterÃsticas quÃmicas e fÃsicas 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 compatÃvel com os concretos de referência. De um modo geral, do ponto de vista técnico, o RSPC não proporcionou resultados satisfatórios para aplicação em concreto
Society for Acute Medicine undergraduate syllabus for Acute Internal Medicine
This syllabus is intended to act as a guide for students and their instructors in medical schools. It describes the range of clinical presentations that they should be able to recognize and the underlying conditions that they should know how to treat. It also includes knowledge of the practice of Acute Internal Medicine and systems of care. The appropriate level of knowledge is that which would be expected of a non-specialist Foundation level doctor.</p
Heat curing and delayed ettringite formation
This paper reports some preliminary results from a study of the effect of elevated temperature curing on mortars and the phenomenon of delayed ettringite formation (DEF). Mortars made from cements with sulphate levels of 3%, 4%, and 5% and with 5% sulphate and added alkali were cured at 20 and 90°C and subsequently stored in water. Expansion measurements showed a pessimum effect with increasing SO3 content. Mortars which expanded showed a corresponding decrease in strength. X-ray diffraction (XRD) studies indicated that no ettringite is present after heat treatment but re-forms over time within the material. However, the ultimate levels of ettringite reached do not correspond to the magnitude of expansion observed. X-ray microanalysis shows that immediately after the heat treatment the aluminate species and most of the sulphate species are incorporated within the C-S-H gel. The concentrations of these species decrease during expansion, such that at the end of expansion the amounts remaining correspond to the presence of AFm phase mixed with C-S-H
YAGO2s: Modular High-Quality Information Extraction with an Application to Flight Planning
Abstract: In this paper, we present YAGO2s, the new edition of the YAGO ontology [SKW07, HSBW12]. The software architecture has been refactored from scratch, yielding a design that modularizes both code and data. This modularization enables us to add in new data sources more easily, while still maintaining the high accuracy and coherence of the ontology. Thus, we believe that YAGO2s occupies a sweetspot between a centralized design and a completely distributed design. In this demo, we present an application of this design to the task of planning a flight. Our proposed system finds flights between all airports close to the departure city to all airports close to the destination city. 1 Knowledge Base Construction In recent years, many projects have successfully created large-scale knowledge bases (KBs) in an automated fashion. The KBs contain millions of entities (such as rivers, universities, people, and movies), and millions of facts about them (such as who acted in which movie, which river is located in which country, etc.). There are several strategies to build such KBs. One strategy is to accumulate and reconcile as much data as possible