232 research outputs found

    Platinum-group element geochemistry of the Forest Reef Volcanics, southeastern Australia: Implications for porphyry Au-Cu mineralisation

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    Platinum-group element concentrations in felsic to intermediate rocks from the Forest Reef Volcanics, Cadia-Neville region, southeastern Australia have been analysed by the Ni-S fire assay-isotope dilution method. The Forest Reef Volcanics are shoshonitic to calc-alkaline in composition and fractionated to produce a wide range of compositions, with MgO varying between 9.7 and 1.8 wt.%. The interest in this suite is that it is coeval with Au-Cu porphyry-style mineralisation in the Cadia mineral district. This study uses PGE geochemistry to determine the timing of sulfide saturation, relative to volatile (ore-fluid) saturation, in the magma that gave rise to the Forest Reef Volcanics and, in turn, to assess how this timing affected the mineralisation potential of the evolving magmatic system. The Forest Reef Volcanics can be subdivided, on the basis of their contrasting PGE geochemistry, into high-Mg (>6.8 wt.% MgO) and low-Mg suites (≤6.8 wt.% MgO). Platinum, Pd and Re concentrations increase in the high-Mg samples, whereas Ir and Ru decrease and Rh concentrations remain steady, with decreasing MgO. The coupled Ir, Ru and Rh depletion is attributed to the partitioning of these elements into magnetite. The rate of Pt and Pd enrichment is not possible by closed-system fractional crystallisation alone, which suggests that the parent magma was replenished by a Pt-Pd-rich melt. In contrast, the PGE concentrations in the low-Mg samples decrease with decreasing MgO indicating the onset of sulfide saturation at 6.8 wt.% MgO, which is confirmed by the presence of spheroidal sulfide inclusions in liquidus crystals (i.e. clinopyroxene, plagioclase, magnetite). The rate of Pd depletion is appreciably less than for any other sulfide saturated felsic system for which data are available. This requires either that the amount of sulfide melt to have precipitated was unusually low, or that the rate of Pd depletion was limited by the mass of silicate melt the sulfide melt reached equilibrium with, or both. In any event, the fraction of sulfide melt that precipitated was too small to have had a significant effect on the Cu and Au content of the magma so that both Cu and Au were available to enter the ore-forming fluid when the magma became volatile saturated at, or shortly after, it reached ca. 2.9 wt.% MgO.This research was funded by a Newcrest Mining LTD Grant to Ian Campbell

    Molecular Genetic Influences on Normative and Problematic Alcohol Use in a Population-Based Sample of College Students

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    Background: Genetic factors impact alcohol use behaviors and these factors may become increasingly evident during emerging adulthood. Examination of the effects of individual variants as well as aggregate genetic variation can clarify mechanisms underlying risk. Methods: We conducted genome-wide association studies (GWAS) in an ethnically diverse sample of college students for three quantitative outcomes including typical monthly alcohol consumption, alcohol problems, and maximum number of drinks in 24 h. Heritability based on common genetic variants (h2SNP) was assessed. We also evaluated whether risk variants in aggregate were associated with alcohol use outcomes in an independent sample of young adults. Results: Two genome-wide significant markers were observed: rs11201929 in GRID1 for maximum drinks in 24 h, with supportive evidence across all ancestry groups; and rs73317305 in SAMD12 (alcohol problems), tested only in the African ancestry group. The h2SNP estimate was 0.19 (SE = 0.11) for consumption, and was non-significant for other outcomes. Genome-wide polygenic scores were significantly associated with alcohol outcomes in an independent sample. Conclusions: These results robustly identify genetic risk for alcohol use outcomes at the variant level and in aggregate. We confirm prior evidence that genetic variation in GRID1impacts alcohol use, and identify novel loci of interest for multiple alcohol outcomes in emerging adults. These findings indicate that genetic variation influencing normative and problematic alcohol use is, to some extent, convergent across ancestry groups. Studying college populations represents a promising avenue by which to obtain large, diverse samples for gene identification

    What are the impacts of within-field farmland management practices on the flux of greenhouse gases from arable cropland in temperate regions? A systematic map protocol

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    Background: Reducing greenhouse gas emissions is a vital step in limiting climate change and meeting the goals outlined in the COP 21 Paris Agreement of 2015. Studies have suggested that agriculture accounts for around 11% of total greenhouse gas emissions and the industry has a significant role in meeting international and national climate change reduction objectives. However, there is currently little consensus on the mechanisms that regulate the production and assimilation of greenhouse gases in arable land and the practical factors that affect the process. Practical advice for farmers is often overly general, and models based on the amount of nitrogen fertiliser applied, for example, are used despite a lack of knowledge of how local conditions affect the process, such as the importance of humus content and soil types. Here, we propose a systematic map of the evidence relating to the impact on greenhouse gas flux from the agricultural management of arable land in temperate regions. Methods: Using established methods for systematic mapping in environmental sciences we will search for, collate and catalogue research studies relating to the impacts of farming in temperate systems on greenhouse gas emissions. We will search 6 bibliographic databases using a tested search string, and will hand search a web-based search engine and a list of organisational web sites. Furthermore, evidence will be sought from key stakeholders. Search results will then be screened for relevance at title, abstract and full text levels according to a predefined set of eligibility criteria. Consistency checking will be employed to ensure the criteria are being applied accurately and consistently. Relevant studies will then be subjected to coding and meta-data extraction, which will be used to populate a systematic map database describing each relevant study's settings, methods and measured outcomes. The mapping process will help to identify knowledge gaps (subjects lacking in evidence warranting further primary research) and knowledge clusters (subjects with sufficient studies to allow a useful full systematic review), and will highlight best and suboptimal research methods

    A large genome-wide association study of age-related macular degeneration highlights contributions of rare and common variants

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    Advanced age-related macular degeneration (AMD) is the leading cause of blindness in the elderly with limited therapeutic options. Here, we report on a study of \u3e12 million variants including 163,714 directly genotyped, most rare, protein-altering variant. Analyzing 16,144 patients and 17,832 controls, we identify 52 independently associated common and rare variants (P \u3c 5×10–8) distributed across 34 loci. While wet and dry AMD subtypes exhibit predominantly shared genetics, we identify the first signal specific to wet AMD, near MMP9 (difference-P = 4.1×10–10). Very rare coding variants (frequency \u3c 0.1%) in CFH, CFI, and TIMP3 suggest causal roles for these genes, as does a splice variant in SLC16A8. Our results support the hypothesis that rare coding variants can pinpoint causal genes within known genetic loci and illustrate that applying the approach systematically to detect new loci requires extremely large sample sizes

    Weaving Indigenous knowledge systems and Western sciences in terrestrial research, monitoring and management in Canada: A protocol for a systematic map

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    Human activities and development have contributed to declines in biodiversity across the globe.Understanding and addressing biodiversity loss will require the mobilization of diverse knowledge systems. While calls for interdisciplinary practices in environmental research date back decades, there has been a more recent push for weaving multiple knowledge systems in environmental research and management, specifically Indigenous knowledge systems (IKS) and Western sciences. The use of multiple knowledge systems in environmental research can improve understanding of socio-ecological connections, build trust in research findings and help implement evidence-based action towards biodiversity conservation. Mobilizing multiple types of knowledge in environmental research and management can be beneficial; however, challenges remain. There is a need to understand how and where studies have woven IKS and Western sciences together in order to learn about frameworks and processes used, and identify best practices. Here, we present a protocol for a systematic map that will examine the extent, range and nature of the published literature that weaves IKS and Western sciences in terrestrial ecosystems research, monitoring and management in Canada. The systematic map will aim to capture all available and relevant studies found in the published academic and grey literature. The search will use standardized search terms across four publication databases, four specialized websites and one web-based search engine. Bibliographies of relevant review articles captured by our search strategy will be cross-checked to identify additional studies. Calls for evidence among professional networks will also complement the search strategy. All searches will be conducted in English. Search results will be reviewed in two stages: (1) title and abstract and (2) full text. All screening decisions at the full-text stage will be included into the map database. The systematic map will use a narrative synthesis approach employing descriptive tables, statistics and figures (including a map with geospatially referenced studies) to summarize findings. Results from this mapping exercise can serve to support environmental research and management efforts working across IKS and Western sciences by highlighting best practices, as well as evidence gaps

    Implementing paediatric appropriate use criteria for endotracheal suction to reduce complications in mechanically ventilated children with respiratory infections

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    BackgroundEndotracheal suction is used to maintain endotracheal tube patency. There is limited guidance to inform clinical practice for children with respiratory infections.ObjectiveThe objective of this study was to determine whether implementation of a paediatric endotracheal suction appropriate use guideline Paediatric AirWay Suction (PAWS) is associated with an increased use of appropriate and decreased use of inappropriate suction interventions.MethodsA mixed-method, pre-implementation–post-implementation study was conducted between September 2021 and April 2022. Suction episodes in mechanically ventilated children with a respiratory infection were eligible. Using a structured approach, we implemented the PAWS guideline in a single paediatric intensive care unit. Evaluation included clinical (e.g., suction intervention appropriateness), implementation (e.g., acceptability), and cost outcomes (implementation costs). Associations between implementation of the PAWS guideline and appropriateness of endotracheal suction intervention use were investigated using generalised linear models.ResultsData from 439 eligible suctions were included in the analysis. Following PAWS implementation, inappropriate endotracheal tube intervention use reduced from 99% to 58%, an absolute reduction (AR) of 41% (95% confidence interval [CI]: 25%, 56%). Reductions were most notable for open suction systems (AR: 48%; 95% CI: 30%, 65%), 0.9% sodium chloride use (AR: 23%; 95% CI: 8%, 38%) and presuction and postsuction manual bagging (38%; 95% CI: 16%, 60%, and 86%; 95% CI: 73%, 99%), respectively. Clinicians perceived PAWS as acceptable and suitable for use.ConclusionsImplementation of endotracheal tube suction appropriate use guidelines in a mixed paediatric intensive care unit was associated with a large reduction in inappropriate suction intervention use in paediatric patients with respiratory infections

    A genome-wide association study for diabetic nephropathy genes in African Americans

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    A genome-wide association study was performed using the Affymetrix 6.0 chip to identify genes associated with diabetic nephropathy in African Americans. Association analysis was performed adjusting for admixture in 965 type 2 diabetic African American patients with end-stage renal disease (ESRD) and in 1029 African Americans without type 2 diabetes or kidney disease as controls. The top 724 single nucleotide polymorphisms (SNPs) with evidence of association to diabetic nephropathy were then genotyped in a replication sample of an additional 709 type 2 diabetes-ESRD patients and 690 controls. SNPs with evidence of association in both the original and replication studies were tested in additional African American cohorts consisting of 1246 patients with type 2 diabetes without kidney disease and 1216 with non-diabetic ESRD to differentiate candidate loci for type 2 diabetes-ESRD, type 2 diabetes, and/or all-cause ESRD. Twenty-five SNPs were significantly associated with type 2 diabetes-ESRD in the genome-wide association and initial replication. Although genome-wide significance with type 2 diabetes was not found for any of these 25 SNPs, several genes, including RPS12, LIMK2, and SFI1 are strong candidates for diabetic nephropathy. A combined analysis of all 2890 patients with ESRD showed significant association SNPs in LIMK2 and SFI1 suggesting that they also contribute to all-cause ESRD. Thus, our results suggest that multiple loci underlie susceptibility to kidney disease in African Americans with type 2 diabetes and some may also contribute to all-cause ESRD

    Author Correction: Cross-ancestry genome-wide association analysis of corneal thickness strengthens link between complex and Mendelian eye diseases.

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    Emmanuelle Souzeau, who contributed to analysis of data, was inadvertently omitted from the author list in the originally published version of this Article. This has now been corrected in both the PDF and HTML versions of the Article

    Systems genetics identifies a role for Cacna2d1 regulation in elevated intraocular pressure and glaucoma susceptibility

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    Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article�s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article�s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.Glaucoma is a multi-factorial blinding disease in which genetic factors play an important role. Elevated intraocular pressure is a highly heritable risk factor for primary open angle glaucoma and currently the only target for glaucoma therapy. Our study helps to better understand underlying genetic and molecular mechanisms that regulate intraocular pressure, and identifies a new candidate gene, Cacna2d1, that modulates intraocular pressure and a promising therapeutic, pregabalin, which binds to CACNA2D1 protein and lowers intraocular pressure significantly. Because our study utilizes a genetically diverse population of mice with known sequence variants, we are able to determine that the intraocular pressure-lowering effect of pregabalin is dependent on the Cacna2d1 haplotype. Using human genome-wide association study (GWAS) data, evidence for association of a CACNA2D1 single-nucleotide polymorphism and primary open angle glaucoma is found. Importantly, these results demonstrate that our systems genetics approach represents an efficient method to identify genetic variation that can guide the selection of therapeutic targets
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