Extreme redox variations in a superdeep diamond from a subducted slab

: The introduction of volatile-rich subducting slabs to the mantle may locally generate large redox gradients, affecting phase stability, element partitioning and volatile speciation1. Here we investigate the redox conditions of the deep mantle recorded in inclusions in a diamond from Kankan, Guinea. Enstatite (former bridgmanite), ferropericlase and a uniquely Mg-rich olivine (Mg# 99.9) inclusion indicate formation in highly variable redox conditions near the 660 km seismic discontinuity. We propose a model involving dehydration, rehydration and dehydration in the underside of a warming slab at the transition zone-lower mantle boundary. Fluid liberated by dehydration in a crumpled slab, driven by heating from the lower mantle, ascends into the cooler interior of the slab, where the H2O is sequestered in new hydrous minerals. Consequent fractionation of the remaining fluid produces extremely reducing conditions, forming Mg-end-member ringwoodite. This fractionating fluid also precipitates the host diamond. With continued heating, ringwoodite in the slab surrounding the diamond forms bridgmanite and ferropericlase, which is trapped as the diamond grows in hydrous fluids produced by dehydration of the warming slab

Lung microbiota predict clinical outcomes in critically ill patients

Rationale: Recent studies have revealed that, in critically ill patients, lung microbiota are altered and correlate with alveolar inflammation. The clinical significance of altered lung bacteria in critical illness is unknown. Objectives: To determine if clinical outcomes of critically ill patients are predicted by features of the lung microbiome at the time of admission. Methods: We performed a prospective, observational cohort study in an ICU at a university hospital. Lung microbiota were quantified and characterized using droplet digital PCR and bacterial 16S ribosomal RNA gene quantification and sequencing. Primary predictors were the bacterial burden, community diversity, and community composition of lung microbiota. The primary outcome was ventilatorfree days, determined at 28 days after admission. Measurements and Main Results: Lungs of 91 critically ill patients were sampled using miniature BAL within 24 hours of ICU admission. Patients with increased lung bacterial burden had fewer ventilator-free days (hazard ratio, 0.43; 95% confidence interval, 0.21-0.88), which remained significant when the analysis was controlled for pneumonia and severity of illness. The community composition of lung bacteria predicted ventilator-free days (P = 0.003), driven by the presence of gutassociated bacteria (e.g., species of the Lachnospiraceae and Enterobacteriaceae families). Detection of gut-associated bacteria was also associated with the presence of acute respiratory distress syndrome. Conclusions: Key features of the lung microbiome (bacterial burden and enrichment with gut-associated bacteria) predict outcomes in critically ill patients. The lung microbiome is an understudied source of clinical variation in critical illness and represents a novel therapeutic target for the prevention and treatment of acute respiratory failure

Diamonds and the mantle geodynamics of carbon:deep mantle carbon evolution from the diamond record

The science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time

Diamonds and the mantle geodynamics of carbon : deep mantle carbon evolution from the diamond record

SBS and EHH for support from the US National Science Foundation (EAR-104992); FN and PN for support from the European Research Council Starting Grant (#307322); Wuyi Wang and Tom Moses of the Gemological Institute of America (GIA) for the support of the research projects undertaken by KVS and EMS; and SCK for the support of De Beers Technologies. This is contribution 1168 from the ARC Centre of Excellence for Core to Crust Fluid Systems (www.ccfs.mq.edu.au) and 1130 in the Geochemical Evolution and Metallogeny of the Continents Key Centre (www.gemoc.mq.edu.au).The science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.Publisher PD

Measurement of D-s(+) and D-s(*+) production in B meson decays and from continuum e(+)e(-) annihilation at root s=10.6 GeV

New measurements of D-s(+) and D-s(*+) meson production rates from B decays and from q(q) over bar continuum events near the Y(4S) resonance are presented. Using 20.8 fb(-1) of data on the Y(4S) resonance and 2.6 fb(-1) off-resonance, we find the inclusive branching fractions B(B-->Ds+X) = (10.93+/-0.19+/-0.58+/-2.73)% and B(B-->Ds*+X) = (7.9+/-0.8+/-0.7+/-2.0)%, where the first error is statistical, the second is systematic, and the third is due to the D-s(+)-->phipi(+) branching fraction uncertainty. The production cross sections sigma(e(+)e(-)-->Ds+X)xB(D-s(+)-->phipi(+)) = 7.55+/-0.20+/-0.34 pb and sigma(e(+)e(-)-->Ds*+/-X)xB(D-s(+)-->phipi(+)) = 5.8+/-0.7+/-0.5 pb are measured at center-of-mass energies about 40 MeV below the Y(4S) mass. The branching fractions SigmaB(B-->D-s((*)+)(D) over bar ((*))) = (5.07+/-0.14+/-0.30+/-1.27)% and SigmaB(B-->D-s(*+)(D) over bar ((*))) = (4.1+/-0.2+/-0.4+/-1.0)% are determined from the D-s((*)+) momentum spectra. The mass difference m(D-s(+)) -m(D+) = 98.4+/-0.1+/-0.3 MeV/c(2) is also measured