Titanates of the lindsleyite–mathiasite (LIMA) group reveal isotope disequilibrium associated with metasomatism in the mantle beneath Kimberley (South Africa)

Radiogenic isotope variations unrelated to radiogenic ingrowth are common between minerals found in metasomatised mantle xenoliths entrained in kimberlite, basalts and related magmas. As the metasomatic minerals are assumed to have been in isotopic equilibrium originally, such variations are typically attributed to contamination by the magma host and/or interaction with mantle fluids during or before xenolith transport to surface. However, the increasing evidence of metasomatism by multiple, compositionally distinct fluids permeating the lithospheric mantle, coeval with specific magmatic events, suggests that isotopic disequilibrium might be a consequence of discrete, though complex, metasomatic events. Here we provide clear evidence of elemental and Sr isotope heterogeneity between coeval Ti-rich LIMA (lindsleyite–mathiasite) minerals at the time of their formation in the mantle. LIMA minerals occur in close textural association with clinopyroxene and phlogopite in low-temperature (∼800–900 °C), strongly metasomatised mantle xenoliths from the ∼84 Ma Bultfontein kimberlite (South Africa). Previous U/Pb dating of the LIMA phases was used to argue that each xenolith recorded a single event of LIMA crystallisation at ∼180–190 Ma, coeval with the emplacement of Karoo magmas. SEM imaging reveals that up to four types of LIMA phases coexist in each xenolith, and occasionally in a single LIMA grain. Major element and in situ Sr isotope analyses of the different LIMA types show that each phase has a distinct elemental composition and initial 87Sr/86Sr ratio (e.g., 0.7068–0.7086 and 0.7115–0.7129 for two LIMA types in a single xenolith; 0.7053-0.7131 across the entire sample suite). These combined age and isotopic constraints require that multiple fluids metasomatised these rocks at broadly the same time (i.e. within a few thousands to millions of years), and produced similar mineralogical features. Elemental and isotopic variations between different LIMA types could be due to interaction between one (or more) Karoo-related Ti-rich silicate melts and previously metasomatised, phlogopite-rich lithospheric mantle. This study demonstrates that mantle metasomatic assemblages seemingly generated in a single event may instead result from the infiltration of broadly coeval fluids with variable compositions. This in turn implies that the isotopic variations recorded in mantle rocks may be an inherent feature of metasomatism, and that hot fluids infiltrating a rock do not necessarily cause equilibration at the cm scale, as has been assumed previously. Simple modelling of solid-state diffusion in mantle minerals shows that isotopic disequilibrium may be preserved for up to hundreds of Myr at mantle lithosphere temperatures (≤1100–1200 °C), unless subsequently affected by transient heating and/or fluid infiltration events. Radiogenic isotope disequilibrium associated with mantle metasomatism may therefore be a common feature of mantle xenoliths

Coordination of care within primary health care and with other sectors: A systematic review

As the population ages and the rate of chronic disease increases, more people are receiving complex regimes of care, from a variety of health care providers. This care must be well coordinated if people with complex needs are to receive care that is comprehensive and continuous, and if they are to take an active role in their care. The need to coordinate care is one of the drivers for health service integration.The research reported in this paper is a project of the Australian Primary Health Care Research Institute, which is supported by a grant from the Australian Government Department of Health and Ageing under the Primary Health Care Research, Evaluation and Development Strategy

Clinical relevance of biomarkers of oxidative stress

SIGNIFICANCE Oxidative stress is considered to be an important component of various diseases. A vast number of methods have been developed and used in virtually all diseases to measure the extent and nature of oxidative stress, ranging from oxidation of DNA to proteins, lipids, and free amino acids. Recent Advances: An increased understanding of the biology behind diseases and redox biology has led to more specific and sensitive tools to measure oxidative stress markers, which are very diverse and sometimes very low in abundance. CRITICAL ISSUES The literature is very heterogeneous. It is often difficult to draw general conclusions on the significance of oxidative stress biomarkers, as only in a limited proportion of diseases have a range of different biomarkers been used, and different biomarkers have been used to study different diseases. In addition, biomarkers are often measured using nonspecific methods, while specific methodologies are often too sophisticated or laborious for routine clinical use. FUTURE DIRECTIONS Several markers of oxidative stress still represent a viable biomarker opportunity for clinical use. However, positive findings with currently used biomarkers still need to be validated in larger sample sizes and compared with current clinical standards to establish them as clinical diagnostics. It is important to realize that oxidative stress is a nuanced phenomenon that is difficult to characterize, and one biomarker is not necessarily better than others. The vast diversity in oxidative stress between diseases and conditions has to be taken into account when selecting the most appropriate biomarker. Antioxid. Redox Signal. 00, 000-000

The association between air pollution and type 2 diabetes in a large cross-sectional study in Leicester: The CHAMPIONS Study

Background: Observational evidence suggests there is an association between air pollution and type 2 diabetes; however, there is high risk of bias. Objective: To investigate the association between air pollution and type 2 diabetes, while reducing bias due to exposure assessment, outcome assessment, and confounder assessment. Methods: Data were collected from 10,443 participants in three diabetes screening studies in Leicestershire, UK. Exposure assessment included standard, prevailing estimates of outdoor nitrogen dioxide and particulate matter concentrations in a 1 × 1 km area at the participant's home postcode. Three-year exposure was investigated in the primary analysis and one-year exposure in a sensitivity analysis. Outcome assessment included the oral glucose tolerance test for type 2 diabetes. Confounder assessment included demographic factors (age, sex, ethnicity, smoking, area social deprivation, urban or rural location), lifestyle factors (body mass index and physical activity), and neighbourhood green space. Results: Nitrogen dioxide and particulate matter concentrations were associated with type 2 diabetes in unadjusted models. There was no statistically significant association between nitrogen dioxide concentration and type 2 diabetes after adjustment for demographic factors (odds: 1.08; 95% CI: 0.91, 1.29). The odds of type 2 diabetes was 1.10 (95% CI: 0.92, 1.32) after further adjustment for lifestyle factors and 0.91 (95% CI: 0.72, 1.16) after yet further adjustment for neighbourhood green space. The associations between particulate matter concentrations and type 2 diabetes were also explained away by demographic factors. There was no evidence of exposure definition bias. Conclusions: Demographic factors seemed to explain the association between air pollution and type 2 diabetes in this cross-sectional study. High-quality longitudinal studies are needed to improve our understanding of the association

TESS Discovery of an ultra-short-period planet around the nearby M dwarf LHS 3844

Data from the newly-commissioned \textit{Transiting Exoplanet Survey Satellite} (TESS) has revealed a "hot Earth" around LHS 3844, an M dwarf located 15 pc away. The planet has a radius of $1.32\pm 0.02$ $R_\oplus$ and orbits the star every 11 hours. Although the existence of an atmosphere around such a strongly irradiated planet is questionable, the star is bright enough ($I=11.9$, $K=9.1$) for this possibility to be investigated with transit and occultation spectroscopy. The star's brightness and the planet's short period will also facilitate the measurement of the planet's mass through Doppler spectroscopy.Comment: 10 pages, 4 figures. Submitted to ApJ Letters. This letter makes use of the TESS Alert data, which is currently in a beta test phase, using data from the pipelines at the TESS Science Office and at the TESS Science Processing Operations Cente