Enhanced cellular preservation by clay minerals in 1 billion-year-old lakes

The article of record as published may be located at http://dx.doi.org/10.1038/srep05841Organic-walled microfossils provide the best insights into the composition and evolution of the biosphere through the first 80 percent of Earth history. The mechanism of microfossil preservation affects the quality of biological information retained and informs understanding of early Earth palaeo-environments. We here show that 1 billion-year-old microfossils from the non-marine Torridon Group are remarkably preserved by a combination of clay minerals and phosphate, with clay minerals providing the highest fidelity of preservation. Fe-rich clay mostly occurs in narrow zones in contact with cellular material and is interpreted as an early microbially-mediated phase enclosing and replacing the most labile biological material. K-rich clay occurs within and exterior to cell envelopes, forming where the supply of Fe had been exhausted. Clay minerals inter-finger with calcium phosphate that co-precipitated with the clays in the sub-oxic zone of the lake sediments. This type of preservation was favoured in sulfate-poor environments where Fe-silicate precipitation could outcompete Fe-sulfide formation. This work shows that clay minerals can provide an exceptionally high fidelity of microfossil preservation and extends the known geological range of this fossilization style by almost 500 Ma. It also suggests that the best-preserved microfossils of this time may be found in low-sulfate environments

Contrasting microfossil preservation and lake chemistries within the 1200–1000 Ma Torridonian Supergroup of NW Scotland

We acknowledge the Australian Microscopy & Microanalysis Research Facility at the Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, a facility funded by the University, State and Commonwealth Governments. DW acknowledges funding from the European Commission and the Australian Research Council. This is publication number 838 from the Australian Research Council Centre of Excellence for Core to Crust Fluid Systems.Publisher PD

Detecting ancient life: Investigating the nature and origin of possible stromatolites and associated calcite from a one billion year old lake

Putative stromatolites and associated carbonate minerals in 1.1 Ga Stoer Group lacustrine sedimentary rocks were analysed to deduce their likely origins. Potential stromatolite examples included finely laminated and sometimes wrinkled carbonate-siliciclastic rocks of the Clachtoll Formation at Clachtoll and Bay of Stoer, and laminated limestone domes of the Poll a’Mhuilt Member (Bay of Stoer Formation) from Enard Bay. Petrography shows that the lamination and wrinkling of Clachtoll Formation specimens can most logically be explained by abiotic siliclastic sedimentary processes, namely rippling and soft-sediment deformation probably related to de-watering. Electron backscatter diffraction shows that the carbonate in these laminated Clachtoll Formation specimens was calcite, and petrography combined with clumped isotope palaeothermometry indicates it was likely to be part syn-depositional and part burial diagenetic in origin. The laminated domes of the Poll a’Mhuilt Member are shown to comprise clasts of limestone interlayered with clay, quartz, Na-rich feldspars and micas. Cathodoluminescence revealed the limestone clasts to be composite and built of sub-grains that must have been derived from an earlier, potentially Palaeoproterozoic, carbonate unit. Support for this hypothesis comes from clumped isotope palaeotemperature measurements that indicate the limestone clasts were precipitated or recrystallized under higher temperature conditions than the burial diagenetic calcite found in the Clachtoll Formation. Raman spectra of an organic carbon particle within a laminated dome of the Poll a’Mhuilt Member at Enard Bay are consistent with the organic carbon having been re-worked from the ∼2 Ga Loch Maree Group, and we speculate that this might also be true of the calcite. Microbial fossils are well known from elsewhere in the Stoer Group, but no conclusive examples were found within the thin-sections examined herein. No conclusive evidence was found to suggest that any of the examined putative stromatolites were biogenic, leading to the conclusion that they are best considered stromatolite-like sedimentary rocks (pseudostromatolites)

Enhanced cellular preservation by clay minerals in 1 billion-year-old lakes

Organic-walled microfossils provide the best insights into the composition and evolution of the biosphere through the first 80 percent of Earth history. The mechanism of microfossil preservation affects the quality of biological information retained and informs understanding of early Earth palaeo-environments. We here show that 1 billion-year-old microfossils from the non-marine Torridon Group are remarkably preserved by a combination of clay minerals and phosphate, with clay minerals providing the highest fidelity of preservation. Fe-rich clay mostly occurs in narrow zones in contact with cellular material and is interpreted as an early microbially-mediated phase enclosing and replacing the most labile biological material. K-rich clay occurs within and exterior to cell envelopes, forming where the supply of Fe had been exhausted. Clay minerals inter-finger with calcium phosphate that co-precipitated with the clays in the sub-oxic zone of the lake sediments. This type of preservation was favoured in sulfate-poor environments where Fe-silicate precipitation could outcompete Fe-sulfide formation. This work shows that clay minerals can provide an exceptionally high fidelity of microfossil preservation and extends the known geological range of this fossilization style by almost 500 Ma. It also suggests that the best-preserved microfossils of this time may be found in low-sulfate environments.David Wacey, Martin Saunders, Malcolm Roberts, Sarath Menon, Leonard Green, Charlie Kong, Timothy Culwick, Paul Strother, Martin D. Brasie

Dressings and securement devices to prevent complications for peripheral arterial catheters

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To compare the effectiveness of dressings and securement devices for peripheral arterial catheters

WebAIRS - A case study: How the multidisciplinarity of IS can save lives

This paper presents a case study chronicling the development of WebAIRS, an Australasian national anaesthetic incident reporting database for health care practitioners. WebAIRS is an example of the multidisciplinary nature of the IS discipline, incorporating IS theories, tools and principles in the creation of an IT artefact with significant real world application. This case study introduces the background of the project and the motivations for its conception including the need for critical incident reporting in anaesthesia, the process of its development using IT students and the problems identified following its national release among the anaesthetic community. The paper demonstrates the evolution of contemporary IS research and the IT artefact, and how each can be crucial foundations for hospitals of the futur

A prospective six-month audit of airway incidents during anaesthesia in twelve tertiary level hospitals across Australia and New Zealand

This audit of airway incidents was conducted over six months in 12 tertiary level hospitals across Australia and New Zealand. During that time, 131,233 patients had airway management and 111 reports were submitted (incidence 0.08%). The airway incidents included a combination of difficult airway management (83), oxygen desaturation (58), aspiration (19), regurgitation (14), laryngospasm (16), airway bleeding (10), bronchospasm (5) and dental injury (4), which gave a total of 209 events in 111 reports. Most incidents occurred during general anaesthesia (GA; 83.8%) and normal working hours (81.1%). Forty-three percent were associated with head and neck surgery and 12.6% with upper abdominal procedures. Of these patients, 52% required further medical treatment or additional procedures and 16.2% required unplanned admission to an intensive care unit or a high dependency unit. A total of 31.5% of patients suffered from temporary harm and 1.8% from permanent harm. There was one death. The factors associated with a high relative risk (RR) of an airway incident included American Society of Anesthesiologists Physical Status (ASA PS) (ASA PS 2 versus 1, RR 1.75; ASA PS 3 versus 1, RR 3.56; ASA PS 4 versus 1, RR 6.1), and emergency surgery (RR 2.16 compared with elective). Sedation and monitored anaesthesia care were associated with lower RRs (RR 0.49 and RR 0.73 versus GA, respectively). Inadequate airway assessment, poor judgement and poor planning appeared to be contributors to these events. Future teaching and research should focus on these areas to further improve airway management and patient safety

Aspiration during anaesthesia in the first 4000 incidents reported to webAIRS

The first 4000 reports to the webAIRS anaesthesia incident reporting database were used to evaluate pulmonary aspiration in patients undergoing procedures under general anaesthesia or sedation. Demographic data, predisposing factors, outcome and potential preventative measures were evaluated. In these reports, 121 cases of aspiration were identified. Aspirated substances included gastric contents, bile type fluids, blood and solids; 60 (49.6%) patients were admitted to the intensive care unit/high dependency unit, and 43 (35.5%) required mechanical ventilation. Aspiration was associated with significant harm in >50% of reports, and eight (6.6%) patients died. Factors associated with a risk ratio of aspiration >1.5 and outside the 95% confidence interval for no event included: age >80 years, emergency procedure, procedure undertaken in freestanding day unit or gastroenterology department, procedure undertaken between 1800 and 2200 hours and endoscopy procedures. Only 11 (9%) cases appeared to be inadequately fasted, and 77 (64%) were definitely fasted. In the remaining 33 (27%), fasting was not mentioned. In 18 (14.9%) cases, aspiration occurred in the presence of cricoid pressure. Potential measures to prevent aspiration included using a cuffed endotracheal tube rather than a laryngeal mask airway in cases at high risk of aspiration and being made more aware of potential risk factors by improvements in team communication. Aspiration continues to be an important complication of anaesthesia, and one that can be difficult to predict and to prevent