ABSTRACT
Subduction related to the ancient supercontinent cycle is poorly constrained by mantle samples. Sublithospheric diamond crystallization records the release of melts from subducting oceanic lithosphere at 300-700 km depths1,2 and is especially suited to tracking the timing and effects of deep mantle processes on supercontinents. Here we show that four isotope systems (Rb-Sr, Sm-Nd, U-Pb and Re-Os) applied to Fe-sulfide and CaSiO3 inclusions within 13 sublithospheric diamonds from Juína (Brazil) and Kankan (Guinea) give broadly overlapping crystallization ages from around 450 to 650 million years ago. The intracratonic location of the diamond deposits on Gondwana and the ages, initial isotopic ratios, and trace element content of the inclusions indicate formation from a peri-Gondwanan subduction system. Preservation of these Neoproterozoic-Palaeozoic sublithospheric diamonds beneath Gondwana until its Cretaceous breakup, coupled with majorite geobarometry3,4, suggests that they accreted to and were retained in the lithospheric keel for more than 300 Myr during supercontinent migration. We propose that this process of lithosphere growth-with diamonds attached to the supercontinent keel by the diapiric uprise of depleted buoyant material and pieces of slab crust-could have enhanced supercontinent stability.
ABSTRACT
Background: Frailty is a known predictor of mortality and poor outcomes during hospital admission. In this large renal retrospective cohort study, we investigated whether frailer COVID-19 positive renal patients had worse outcomes. Design: All SARS-Cov-2 positive renal patients aged ≥18 years who presented to the emergency department at the Royal Free Hospital or at the satellite dialysis centres from 10th of March until the 10th of May 2020, with recent data on frailty, were included. The follow up was until 26th of May 2020. Age, gender, ethnicity, body mass index, chronic kidney disease stage, modality of renal replacement therapy, co-morbidities, Rockwood clinical frailty score (CFS), C reactive protein and the neutrophil-to-lymphocyte count were collected at presentation. The primary outcome was the overall mortality rate following COVID-19 diagnosis. Secondary outcomes included the need for hospital admission. Results: A total of 200 renal patients were SARS-Cov-2 positive. In the 174 patients who had a CFS recorded, the age was 65.4 years ± 15.8 (mean ± SD) and 57,5% were male. At the end of follow up, 26% had died. Frail patients (CFS 5-7) were more than three times more likely to die compared to less frail patients (CFS of 1-4) (odds ratio (OR) 3.3, 95% confidence interval (CI) 1.0-10.6). 118 patients (68%) required admission, but there was no difference in hospital admission rates for frail vs non-frail patients (OR 0.6, CI 0.3-1.7). Conclusions: Frailty is a better predictor of mortality than age and co-morbidities in COVID-19 positive renal patients.
