Palustrine wetland formation during the MIS 3 interstadial: implications for preserved alluvial records in the South African Karoo

Dryland alluvial successions across interior South Africa are a focus of pedosedimentary research because they provide insights into past hydrogeomorphic changes and improve our understanding of allogenic and autogenic controls on fluvial systems. This paper focuses on an alluvial succession preserved within the Wilgerbosch River, on the Great Escarpment, South Africa. The pedosedimentary architecture of a calcretized palaeosol formed within an abandoned MIS 3 (51–39 ka) floodplain was investigated using grain size, micromorphological, XRD and mineral magnetic analyses. The primary controls on pedogenesis are inferred and the impacts of their products on subsequent landscape development outlined. The biologically-dominated calcrete micromorphology is consistent with the rhizogenic calcrete variety, which together with XRD, grain size and soil magnetic data provides evidence for an MIS 3 palustrine palaeowetland system. Palustrine wetlands have been documented across interior South Africa, but have not been previously associated with rhizogenic calcrete formation. We interpret these wetlands to be representative of basin-wide hydrogeomorphic adjustments rather than localised discontinuous channel and floodout processes. Magnetic enhancement (pedogenic maghemite) of the soil column overlying the calcrete compared to the overlying floodplain deposits is indicative of moister climate conditions ~51 ka relative to ~39 ka. We hypothesise that the longevity of the geomorphic quiescence, coupled with relatively moist climate conditions in early MIS 3 enhanced the weathering of calcic plagioclases, resulting in soil CaCO3 accumulation. The resultant cementation of this abandoned floodplain deposit accounts for an alluvial record that is dominated by older rather than younger (e.g. Holocene) deposits, despite the narrow valley context (<150 m). These findings illustrate the interplay of factors that may generate sedimentary records in this and other confined catchment systems. Such insights may aid interpretation of tectonically-stable dryland inland valleys preserved within the geological record

Supplemental parenteral nutrition in critically ill patients: A study protocol for a phase II randomised controlled trial

Background: Nutrition is one of the fundamentals of care provided to critically ill adults. The volume of enteral nutrition received, however, is often much less than prescribed due to multiple functional and process issues. To deliver the prescribed volume and correct the energy deficit associated with enteral nutrition alone, parenteral nutrition can be used in combination (termed "supplemental parenteral nutrition"), but benefits of this method have not been firmly established. A multi-centre, randomised, clinical trial is currently underway to determine if prescribed energy requirements can be provided to critically ill patients by using a supplemental parenteral nutrition strategy in the critically ill. Methods/design: This prospective, multi-centre, randomised, stratified, parallel-group, controlled, phase II trial aims to determine whether a supplemental parenteral nutrition strategy will reliably and safely increase energy intake when compared to usual care. The study will be conducted for 100 critically ill adults with at least one organ system failure and evidence of insufficient enteral intake from six intensive care units in Australia and New Zealand. Enrolled patients will be allocated to either a supplemental parenteral nutrition strategy for 7 days post randomisation or to usual care with enteral nutrition. The primary outcome will be the average energy amount delivered from nutrition therapy over the first 7 days of the study period. Secondary outcomes include protein delivery for 7 days post randomisation; total energy and protein delivery, antibiotic use and organ failure rates (up to 28 days); duration of ventilation, length of intensive care unit and hospital stay. At both intensive care unit and hospital discharge strength and health-related quality of life assessments will be undertaken. Study participants will be followed up for health-related quality of life, resource utilisation and survival at 90 and 180 days post randomisation (unless death occurs first). Discussion: This trial aims to determine if provision of a supplemental parenteral nutrition strategy to critically ill adults will increase energy intake compared to usual care in Australia and New Zealand. Trial outcomes will guide development of a subsequent larger randomised controlled trial. Trial registration:NCT01847534(First registered 5 February 2013, last updated 14 October 2015