348 research outputs found

    Beating heart coronary surgery and renal function: a prospective randomised study (Presented at 18th Spring Meeting of the Association of Cardiothoracic Anaesthetists: Selected abstracts, Cambridge, UK. 22 June 2001)

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    Introduction Cardiopulmonary bypass (CPB) is widely regarded as an important contributor to renal failure, a well recognised complication, following coronary artery surgery (CABG). Off-pump coronary surgery (OPCAB) is intuitively considered renoprotective. We examine the extent of renal glomerular and tubular injury in low-risk patients undergoing either OPCAB or on-pump coronary artery bypass (ONCAB).Methods Forty patients awaiting elective CABG were prospectively randomized into those undergoing OPCAB (n = 20) and ONCAB (n = 20). Table 1 illustrates the exclusion criteria. Glomerular and tubular injury were assessed, respectively, by urinary excretion of microalbumin and retinol binding protein (RBP) indexed to urinary creatinine [1]. Daily measurements were made from admission to postoperative day 5. Fluid balance, serum creati-nine and blood urea were also monitored. Results No mortality or renal complication was observed. Both groups had similar demographic make-up. The OPCAB group received fewer coronary grafts than their counterparts (1.8 versus 2.8; P = 0.002). Serum creatinine and blood urea remained normal in both groups throughout the study. A dramatic and similar rise in mean ± 2SD urinary RBP:creatinine ratio occurred in both groups peaking on day 1 (3183 ± 2534 versus 4035 ± 4078; P = 0.43) before returning to baseline levels. These trends were also observed with the urinary microalbumin:creatinine ratio (5.05 ± 2.66 versus 6.77 ± 5.76; P = 0.22). ONCAB patients had a significantly more negative fluid balance on postoperative day 2 (-183 ± 1118 versus 637 ± 847 ml; P < 0.05). Conclusions Although renal dysfunction did not clinically occur in any patient, sensitive indicators revealed significant and similar injury to both renal tubules and glomeruli following either OPCAB or ONCAB. These suggest that avoidance of CPB per se does not offer additional renoprotection to patients at low risk of perioperative renal insult during CABG

    Lowland river responses to intraplate tectonism and climate forcing quantified with luminescence and cosmogenic 10Be

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    Intraplate tectonism has produced large-scale folding that steers regional drainage systems, such as the 1600 km-long Cooper Ck, en route to Australia’s continental depocentre at Lake Eyre. We apply cosmogenic 10Be exposure dating in bedrock, and luminescence dating in sediment, to quantify the erosional and depositional response of Cooper Ck where it incises the rising Innamincka Dome. The detachment of bedrock joint-blocks during extreme floods governs the minimum rate of incision (17.4±6.5 mm/ky) estimated using a numerical model of episodic erosion calibrated with our 10Be measurements. The last big-flood phase occurred no earlier than ~112–121ka. Upstream of the Innamincka Dome long-term rates of alluvial deposition, partly reflecting synclinal-basin subsidence, are estimated from 47 luminescence dates in sediments accumulated since ~270 ka. Sequestration of sediment in subsiding basins such as these may account for the lack of Quaternary accumulation in Lake Eyre, and moreover suggests that notions of a single primary depocentre at base-level may poorly represent lowland, arid-zone rivers. Over the period ~75–55 ka Cooper Ck changed from a bedload- dominant, laterally-active meandering river to a muddy anabranching channel network up to 60 km wide. We propose that this shift in river pattern was a product of base-level rise linked with the slowly deforming syncline–anticline structure, coupled with a climate-forced reduction in discharge. The uniform valley slope along this subsiding alluvial and rising bedrock system represents an adjustment between the relative rates of deformation and the ability of greatly enhanced flows at times during the Quaternary to incise the rising anticline. Hence, tectonic and climate controls are balanced in the long term

    Solution-processable 2,1,3-benzothiadiazole containing compound based on the novel 1-dodecyl-6-dodecoxynaphthyridine-2-one unit for organic field-effect transistors

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    Small molecule organic semiconductors have well-defined structures and can be used in place of polymers which often show batch-to-batch variation. Many different electron-rich donor and electron-deficient acceptor units have been used to design materials with reduced HOMO-LUMO gaps and improved mobilities. Here we introduce a novel acceptor unit, 1-dodecyl-6-dodecoxynaphthyridine-2-one. This acceptor unit has been used in the synthesis of two novel compounds, with thiophene and 2,1,3-benzothiadiazole (BT) cores. The BT-containing compound shows a narrower HOMO-LUMO gap, broad solid-state absorption and has been applied to organic field-effect transistors, showing a mobility of 0.022 cm2 V−1 s−1 after optimisation of devices using self-assembled monolayers

    Radiocarbon and geochemical constraints on shallow groundwater recharge in a large arid zone river, Cooper Creek, SW Queensland, Australia.

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    In the arid and semi-arid internally drained Lake Eyre Basin of central Australia, large mud dominated anabranching river systems transport monsoon derived floodwaters into the centre of the continent during the summer months, and subsequently spend much of the year under low to no flow conditions. Cooper Creek has the largest catchment in this basin, and in south west Queensland has a wide (20-60km) floodplain and multiple channel system. Enlarged channel segments, known as waterholes or billabongs, can retain water throughout much of the dry season, and their mud base can often be scoured during floods into the underlying sandy alluvium where the shallow groundwater table exists 3-5m below the base of the waterholes. Little is known of the groundwater recharge mechanisms in this ecologically important and hydrologically unregulated river system, thus a number of piezometer transects were construct across the floodplain between two waterholes to investigate groundwater recharge processes in further detail. Samples recovered from all piezometers were analysed for major-trace element, water stable isotopes (δ2H and δ180), 3H and 14C. Water stable isotopes reveal shallow groundwater is recharged by high magnitude, low frequency monsoonal flood events, with minor evaporative enrichment probably linked to recent smaller flooding events. 14C dating of dissolved inorganic carbon reveals recharge is most effective beneath the deepest channel segments of the waterholes, and that residence time of the shallow groundwater increases with distance from major waterholes, with the post 1950’s 14C bomb pulse signature present only in close proximity to the channels. 3H allows further refinement of the shallow groundwater residence times, with no 3H detected in groundwater over ~500m from the waterholes, indicating groundwater recharge is slow and restricted to major flooding events. The increase in groundwater residence time with distance from waterholes, is also accompanied by an abrupt increase in salinity, and suggests recent recharge has formed local freshwater lenses above the regional, more saline groundwater. This increase in salinity with increasing distance from the waterholes is not accompanied by an increase on the evaporative signal of water stable isotopes, suggesting evapotranspiration is the dominant mechanism of salinisation within the shallow groundwater beneath the floodplains and minor channels. This study demonstrates that detailed chemical analysis of groundwaters from arid and semi arid areas can provide a useful estimate of recharge where the remote location makes traditional detailed borehole monitoring difficult or impossible to achieve

    Erosion and the sediment conveyor in central Australia

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    Why are the Neogene sedimentary fills across central Australia generally thin and discontinuous? One long-standing explanation is that sluggish tectonism and intensified aridity have combined to suppress rates of erosion and sediment production yielding a landscape crowded with inherited, preMiocene forms. Quantifying rates of sediment production, residence time and transport is possible with numerous methods, but the recent growth of cosmogenic nuclide (CN) analysis has provided unprecedented quantitative insights to rates of landscape evolution. Measurements of in situ produced cosmogenic 10Be and 26Al integrate rates of surface processes over million-year timescales—the last part of the Neogene in which aridity has strengthened across the continental interior. We present a compilation of ~600 published and unpublished 10Be and 26Al measurements from central Australia with a focus on the Neogene Eyre Basin and its periphery. Outlying and inlying bedrock uplands serve as engines of sediment production via erosion of bedrock. Surrounding the bedrock outcrops are vast sediment conveyors of varying efficiency and tempo: hillslopes, pediments, and alluvial fans are interim storage/burial zones for sediment in transit to the network of low-gradient rivers, dunes, and playas towards base level. Interactions between fluvial and aeolian processes are especially pertinent to sediment flux in the Eyre Basin. Major rivers such as the Cooper and Finke traverse dunefields in their lower reaches where quantities of alluvia are recirculated into dunes and vice versa. Tracking the trajectories of sediment from source-to-sink (including aeolian recirculation) remains a major challenge, but is central to unravelling the sedimentary dynamics of central Australia's Neogene basins. Based on the CN compilation we estimate 1) spatially averaged erosion rates at the scale of a hillslope or river catchment; 2) pointbased erosion rates on bedrock surfaces; 3) residence time of sediment in hillslope regolith and alluvial fans; and 4) cumulative burial history of sediments in transit. Catchment-scale erosion rates (n~100) are consistently low (<10 m/Myr) and include some of the lowest rates ever measured (~0.3 m/Myr); however, a small group of catchments in the Flinders Ras yield higher erosion rates (~30–60 m/Myr). Bedrock hillslopes (n~200) tend to erode even slower (<5 m/Myr), with a subset of Flinders Ras sites again being the exception (~10–30 m/Myr) and suggesting the influence of recent tectonism. Several CN depth-profiles measured on hillslopes and alluvial fans indicate sediment residence times >0.5 Myr, and high-resolution sampling along three hillslopes with differing morphology (linear, convex, and concave) reveals major variations in sediment production and transport rates that hint at the long-term evolution. In the rivers, fluvial sediments show a weak tendency to increase cumulative burial history downstream (1–2 Myr), consistent with the expanding accommodation space for storage and burial. Dune sediments sampled in the Simpson and Tirari dunefields (n~16) contain cumulative burial histories (up to 1.5 Myr) similar to that of the intersecting rivers. This points to an intimate mix of fluvial and aeolian processes in areas approaching base level. Curiously, these sediments occur in the lowest part of the continent and contain the longest histories of cumulative burial, yet do not form part of the thickest sedimentary fills in the Eyre Basin

    A two-part seabed geomorphology classification scheme : (v.2). Part 1 : morphology features glossary

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    This report updates the ‘Two-part Seabed Geomorphology classification scheme’ of Dove et al. (2016) and presents a new glossary (Part 1) of Seabed Morphology features. This Morphology glossary is intended to provide marine scientists with a robust and consistent way to characterise the seabed. Each glossary entry includes a feature definition and a representative schematic diagram to support clear and accurate classification. Feature terms and definitions are primarily drawn from the International Hydrographic Organization (IHO) guide for undersea feature names, which are herein modified and augmented with additional terms to ensure the final feature catalogue and glossary encompasses the diversity of morphologies observed at the seabed, while also minimising duplication and/or ambiguity. This updated classification system and new glossary are the result of a collaboration between marine geoscientists from marine mapping programmes/networks in Norway (MAREANO), Ireland (INFOMAR), UK (MAREMAP), and Australia (Geoscience Australia) (MIM-GA). A subsequent report will present the (Part 2) Geomorphology feature glossar

    Continental aridification and the vanishing of Australia\u27s megalakes

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    The nature of the Australian climate at about the time of rapid megafaunal extinctions and humans arriving in Australia is poorly understood and is an important element in the contentious debate as to whether humans or climate caused the extinctions. Here we present a new paleoshoreline chronology that extends over the past 100 k.y. for Lake Mega-Frome, the coalescence of Lakes Frome, Blanche, Callabonna and Gregory, in the southern latitudes of central Australia. We show that Lake Mega-Frome was connected for the last time to adjacent Lake Eyre at 50-47 ka, forming the largest remaining interconnected system of paleolakes on the Australian continent. The final disconnection and a progressive drop in the level of Lake Mega-Frome represents a major climate shift to aridification that coincided with the arrival of humans and the demise of the megafauna. The supply of moisture to the Australian continent at various times in the Quaternary has commonly been ascribed to an enhanced monsoon. This study, in combination with other paleoclimate data, provides reliable evidence for periods of enhanced tropical and enhanced Southern Ocean sources of water filling these lakes at different times during the last full glacial cycle. © 2011 Geological Society of America

    Understanding stigma of dementia during COVID-19: a scoping review

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    IntroductionStigma of dementia is one of the greatest challenges for people living with dementia. However, there is little research on the different types of stigma of dementia in the COVID-19 pandemic. The purpose of this scoping review is to synthesize the existing literature on dementia-related stigma (self, public, and structural stigma), during the pandemic.MethodsGuided by Arksey and O’Malley’s scoping review framework and PRISMA guidelines, CINAHL, EMBASE, Google Scholar, Medline, PsycINFO, and Web of Science were searched for English language literature from January 2020 to June 2023. Inclusion criteria consisted of peer-reviewed, original research articles addressing stigma of dementia during the COVID-19 pandemic. Thematic analysis was used to analyze the data and steps were taken to ensure rigor.ResultsFifteen articles met our inclusion criteria. Four primary themes were identified including: 1) COVID-19 stereotypes and assumptions of dementia; 2) human rights issues and deprived dignity; 3) disparate access to health services and supports; and 4) cultural inequities and distrust.DiscussionThe COVID-19 pandemic has contributed to the stigmatization of people living with dementia. Further research is needed to develop, implement, and evaluate interventions targeted towards the different types of dementia-related stigma (including self, public, and structural stigma). Moreover, our findings highlight the need for more collaborative research that prioritizes the lived experience and input of diverse people living with dementia. Research partnerships with diverse people living with dementia are vital to improving future pandemic planning. Only through evidence-informed research and lived experience can we begin to fully address the different types of dementia-related stigma and enhance the quality of life of people living with dementia
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