Mineralogical constraints on the genesis of an alkalic-type epithermal Au-Te deposit: Tuvatu, Fiji

To study the characteristics and genetic constraints on alkalic-type epithermal Au mineralisation, here we use the example of the Tuvatu Au-Ag deposit in Fiji, with an emphasis on detailed, quantitative mineralogy. Tuvatu mineralisation is hosted in a weakly altered potassic monzonite in parallel sided-veins of K-feldspar, biotite, sericite, calcite, and quartz, with epidote-bearing propylitic or sericite-rich selvages. Petrographic study of core and automated SEM-based mineralogical mapping of thin sections have been utilised to update previous parageneses of the deposit. Automated SEM techniques enable identification of small amounts of obscure minerals that form minuscule grains, which would otherwise be very difficult to identify and measure. As a result, our data show that gold fineness is extremely high, with the mean and median Au content of native-Au and Au-Ag alloy being 96.7% and 100% respectively, yet precious-metal tellurides make up the majority of the Au deportment. Tellurides show evidence of multiple phases and zoning with depth. For the first time at Tuvatu, Pt- and Pd-tellurides have been identified. Tuvatu has a number of features in common with alkalic systems elsewhere, including quartz-poor, carbonate-rich veins and alteration, abundant and varied telluride minerals, high gold grades, and Pt-Pd occurrences. We suggest these characteristics are a result of relatively high temperature (250–300 °C) fluids and immiscible semi-metal melts fluxing into the shallow epithermal environment. High pH fluids lead to quartz-poor alteration, but mildly acidic conditions dominate in areas of high fluid flux, where the lower pH causes precipitation of tellurides with quartz. Boiling of the fluids produces zonation of tellurides with depth but leaves relatively subtle textural evidence compared to boiling in most epithermal systems, in common with other quartz poor, carbonate-rich alkalic epithermal deposits around the world.</p

Seasonal and daytime variation in multiple immune parameters in humans: evidence from 329,261 participants of the UK Biobank cohort

Seasonal disease outbreaks are perennial features of human infectious disease but the factors generating these patterns are unclear. Here we investigate seasonal and daytime variability in multiple immune parameters in 329,261 participants in UK Biobank and test for associations with a wide range of environmental and lifestyle factors, including changes in day length, outdoor temperature and vitamin D at the time the blood sample was collected. Seasonal patterns were evident in lymphocyte and neutrophil counts, and C-reactive protein CRP, but not monocytes, and these were independent of lifestyle, demographic, and environmental factors. All the immune parameters assessed demonstrated significant daytime variation that was independent of confounding factors. At a population level, human immune parameters vary across season and across time of day, independent of multiple confounding factors. Both season and time of day are fundamental dimensions of immune function that should be considered in all studies of immuno-prophylaxis and disease transmission.</p

Geosciences and the Energy Transition

A substantial and rapid decarbonisation of the global economy is required to limit anthropogenic climate change to well below 2°C average global heating by 2050. Yet, emissions from fossil fuel energy generation—which dominate global greenhouse gas emissions—are at an all-time high. Progress and action for an energy transition to net zero carbon is critical, and one in which geoscience sectors and geoscientists will play multiple roles. Here, we outline the landscape of the geosciences and the energy transition in the context of the climate crisis, and intergovernmental policies on climate and social justice. We show how geoscience sectors, skills, knowledge, data, and infrastructure, both directly and indirectly, will play a key role in the energy transition. This may be in the responsible sourcing of raw materials for low carbon energy technologies; in the decarbonisation of heating; and in the near-permanent geological capture and storage of carbon through novel technology development. A new and unprecedented challenge is to reach Geological Net Zero, where zero carbon emissions from geological resource production and consumption are achieved via permanent geological storage. We identify overarching and cross-cutting issues for a sustainable and fair net zero carbon energy transition, and the associated geoscience challenges and opportunities. Finally, we call for geoscience professionals to recognise and take responsibility for their role in ensuring a fair and sustainable energy transition at the pace and scale required

Geosciences and the Energy Transition

A substantial and rapid decarbonisation of the global economy is required to limit anthropogenic climate change to well below 2°C average global heating by 2050. Yet, emissions from fossil fuel energy generation—which dominate global greenhouse gas emissions—are at an all-time high. Progress and action for an energy transition to net zero carbon is critical, and one in which geoscience sectors and geoscientists will play multiple roles. Here, we outline the landscape of the geosciences and the energy transition in the context of the climate crisis, and intergovernmental policies on climate and social justice. We show how geoscience sectors, skills, knowledge, data, and infrastructure, both directly and indirectly, will play a key role in the energy transition. This may be in the responsible sourcing of raw materials for low carbon energy technologies; in the decarbonisation of heating; and in the near-permanent geological capture and storage of carbon through novel technology development. A new and unprecedented challenge is to reach Geological Net Zero, where zero carbon emissions from geological resource production and consumption are achieved via permanent geological storage. We identify overarching and cross-cutting issues for a sustainable and fair net zero carbon energy transition, and the associated geoscience challenges and opportunities. Finally, we call for geoscience professionals to recognise and take responsibility for their role in ensuring a fair and sustainable energy transition at the pace and scale required

Detecting recurrent major depressive disorder within primary care rapidly and reliably using short questionnaire measures

Background: Major depressive disorder (MDD) is often a chronic disorder with relapses usually detected and managed in primary care using a validated depression symptom questionnaire. However, for individuals with recurrent depression the choice of which questionnaire to use and whether a shorter measure could suffice is not established. Aim: To compare the nine-item Patient Health Questionnaire (PHQ-9), the Beck Depression Inventory, and the Hospital Anxiety and Depression Scale against shorter PHQ-derived measures for detecting episodes of DSM-IV major depression in primary care patients with recurrent MDD. Design and setting: Diagnostic accuracy study of adults with recurrent depression in primary care predominantly from Wales. Method: Scores on each of the depression questionnaire measures were compared with the results of a semi-structured clinical diagnostic interview using Receiver Operating Characteristic curve analysis for 337 adults with recurrent MDD. Results: Concurrent questionnaire and interview data were available for 272 participants. The onemonth prevalence rate of depression was 22.2%. The area under the curve (AUC) and positive predictive value (PPV) at the derived optimal cut-off value for the three longer questionnaires were comparable (AUC = 0.86-0.90, PPV = 49.4-58.4%) but the AUC for the PHQ-9 was significantly greater than for the PHQ-2. However, by supplementing the PHQ-2 score with items on problems concentrating and feeling slowed down or restless, the AUC (0.91) and the PPV (55.3%) were comparable with those for the PHQ-9. Conclusion: A novel four-item PHQ-based questionnaire measure of depression performs equivalently to three longer depression questionnaires in identifying depression relapse in patients with recurrent MDD

Hornblendites as a record of differentiation, metasomatism and magma fertility in arc crust

The fractionation of hornblende is a common phenomenon in arc magmas, and gives rise to a number of notable geochemical characteristics. However, it is often cryptic, with limited direct petrographic evidence for the fractionation, or even presence of amphibole in volcanic suites. Newly identified hornblendites in the SE Tibet represent direct evidence for hornblende fractionation in the Gangdese arc. The hornblendites have age ranges from 95.3 ± 0.2 to 92.6 ± 0.2 Ma, recording magmatic activities over a ca. 2 Myr interval. Textural relationships indicate that hornblendites form by peritectic reactions between an evolving melt and earlier-formed clinopyroxenites. Relict clinopyroxenes and primitive pargasite record melt evolution from high Sr/Y basaltic andesite to dacite, during cooling from ~1050 °C to ~850 °C in the mid to lower crust. The clinopyroxene precursors interacted with water-rich high SiO2 fluids/melts at ca. 800 °C. Zircons have high δ18O values (up to 7.62‰) and positive εHf(t) values (up to +13.0), but bulk rock data show high 87Sr/86Sr ratios (up to 0.7093) and negative εNd(t) values (ca. −3.2). This decoupled signature implies the primary magmatic source was metasomatized by 5–10% recycled subducted sediments. Magmas have a high oxygen fugacity (ΔNNO can up to +2.40) through a combination of metasomatism during subduction, and subsequent melt-mush interaction that is recorded by zoned hornblendes. Metasomatism, widespread and long-term fractionation of amphibole ± garnet ± clinopyroxene, and high oxygen fugacity, are all positive indicators for the fertility of arc magmas with respect to porphyry copper formation. This study demonstrates that late-stage melt-mush interaction can contribute to peritectic hornblendite formation and facilitate magma fertility.</p

Hornblendites as a record of differentiation, metasomatism and magma fertility in arc crust

The fractionation of hornblende is a common phenomenon in arc magmas, and gives rise to a number of notable geochemical characteristics. However, it is often cryptic, with limited direct petrographic evidence for the fractionation, or even presence of amphibole in volcanic suites. Newly identified hornblendites in the SE Tibet represent direct evidence for hornblende fractionation in the Gangdese arc. The hornblendites have age ranges from 95.3 ± 0.2 to 92.6 ± 0.2 Ma, recording magmatic activities over a ca. 2 Myr interval. Textural relationships indicate that hornblendites form by peritectic reactions between an evolving melt and earlier-formed clinopyroxenites. Relict clinopyroxenes and primitive pargasite record melt evolution from high Sr/Y basaltic andesite to dacite, during cooling from ~1050 °C to ~850 °C in the mid to lower crust. The clinopyroxene precursors interacted with water-rich high SiO2 fluids/melts at ca. 800 °C. Zircons have high δ18O values (up to 7.62‰) and positive εHf(t) values (up to +13.0), but bulk rock data show high 87Sr/86Sr ratios (up to 0.7093) and negative εNd(t) values (ca. −3.2). This decoupled signature implies the primary magmatic source was metasomatized by 5–10% recycled subducted sediments. Magmas have a high oxygen fugacity (ΔNNO can up to +2.40) through a combination of metasomatism during subduction, and subsequent melt-mush interaction that is recorded by zoned hornblendes. Metasomatism, widespread and long-term fractionation of amphibole ± garnet ± clinopyroxene, and high oxygen fugacity, are all positive indicators for the fertility of arc magmas with respect to porphyry copper formation. This study demonstrates that late-stage melt-mush interaction can contribute to peritectic hornblendite formation and facilitate magma fertility.</p

Associations between schizophrenia genetic risk, anxiety disorders and manic/hypomanic episode in a longitudinal population cohort study

Background Studies involving clinically recruited samples show that genetic liability to schizophrenia overlaps with that for several psychiatric disorders including bipolar disorder, major depression and, in a population study, anxiety disorder and negative symptoms in adolescence. Aims We examined whether, at a population level, association between schizophrenia liability and anxiety disorders continues into adulthood, for specific anxiety disorders and as a group. We explored in an epidemiologically based cohort the nature of adult psychopathology sharing liability to schizophrenia. Method Schizophrenia polygenic risk scores (PRSs) were calculated for 590 European-descent individuals from the Christchurch Health and Development Study. Logistic regression was used to examine associations between schizophrenia PRS and four anxiety disorders (social phobia, specific phobia, panic disorder and generalised anxiety disorder), schizophrenia/schizophreniform disorder, manic/hypomanic episode, alcohol dependence, major depression, and – using linear regression – total number of anxiety disorders. A novel population-level association with hypomania was tested in a UK birth cohort (Avon Longitudinal Study of Parents and Children). Results Schizophrenia PRS was associated with total number of anxiety disorders and with generalised anxiety disorder and panic disorder. We show a novel population-level association between schizophrenia PRS and manic/hypomanic episode. Conclusions The relationship between schizophrenia liability and anxiety disorders is not restricted to psychopathology in adolescence but is present in adulthood and specifically linked to generalised anxiety disorder and panic disorder. We suggest that the association between schizophrenia liability and hypomanic/manic episodes found in clinical samples may not be due to bias

Modular microfluidics enables kinetic insight from time-resolved cryo-EM

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