Evaluating the formation pressure of diamond-hosted majoritic garnets; A machine-learning barometer

Diamond‐hosted majoritic garnet inclusions provide unique insights into the Earth's deep, and otherwise inaccessible, mantle. Compared with other types of mineral inclusions found in sub‐lithospheric diamonds, majoritic garnets can provide the most accurate estimates of diamond formation pressures because laboratory experiments have shown that garnet chemistry varies strongly as a function of pressure. However, evaluation using a compilation of experimental data demonstrates that none of the available empirical barometers are reliable for predicting the formation pressure of many experimental majoritic garnets and cannot be applied with confidence to diamond‐hosted garnet inclusions. On the basis of the full experimental data set, we develop a novel type of majorite barometer using machine learning algorithms. Cross validation demonstrates that Random Forest Regression allows accurate prediction of the formation pressure across the full range of experimental majoritic garnet compositions found in the literature. Applying this new barometer to the global database of diamond‐hosted inclusions reveals that their formation occurs in specific pressure modes. However, exsolved clinopyroxene components that are often observed within garnet inclusions are not included in this analysis. Reconstruction of inclusions, in the 8 cases where this is currently possible, reveals that ignoring small exsolved components can lead to underestimating inclusion pressures by up to 7 GPa (∼210 km). The predicted formation pressures of majoritic garnet inclusions are consistent with crystallization of carbon‐rich slab‐derived melts in Earth's deep upper mantle and transition zone

Extensive, water-rich magma reservoir beneath southern Montserrat

South Soufriere Hills and Soufriere Hills volcanoes are two km apart at the southern end of the island of Montserrat, West Indies. Their magmas are distinct geochemically, despite these volcanoes having been active contemporaneously at 131-129 ka. We use the water content of pyroxenes and melt inclusion data to reconstruct the bulk water contents of magmas and their depth of storage prior to eruption. Pyroxenes contain up to 281 ppm H2O, with significant variability between crystals and from core to rim in individual crystals. The Al content of the enstatites from Soufriere Hills Volcano (SHV) is used to constrain melt-pyroxene partitioning for H2O. The SHV enstatite cores record melt water contents of 6-9 wt%. Pyroxene and melt inclusion water concentration pairs from South Soufriere Hills basalts independently constrain pyroxene-melt partitioning of water and produces a comparable range in melt water concentrations. Melt inclusions recorded in plagioclase and in pyroxene contain up to 6.3 wt% H2O. When combined with realistic melt CO2 contents, the depth of magma storage for both volcanoes ranges from 5 to 16 km. The data are consistent with a vertically protracted crystal mush in the upper crust beneath the southern part of Montserrat which contains heterogeneous bodies of eruptible magma. The high water contents of the magmas suggest that they contain a high proportion of exsolved fluids, which has implications for the rheology of the mush and timescales for mush reorganisation prior to eruption. A depletion in water in the outer 50-100 microns of a subset of pyroxenes from pumices from a Vulcanian explosion at Soufriere Hills in 2003 is consistent with diffusive loss of hydrogen during magma ascent over 5-13 hours. These timescales are similar to the mean time periods between explosions in 1997 and in 2003, raising the possibility that the driving force for this repetitive explosive behaviour lies not in the shallow system, but in the deeper parts of a vertically protracted crustal magma storage system.ME acknowledges NERC grant NE/I016694/1 and NERC ion probe facility grant IMF429/0511 and Cees-Jan de Hoog, who provided invaluable assistance with SIMS measurements and calibration. MC acknowledges an Alexander Von Humboldt fellowship.This is the author accepted manuscript. The final version is available from Elsevier via https://doi.org/10.1016/j.lithos.2016.02.02

Stable isotope evidence for crustal recycling as recorded by superdeep diamonds

© 2015 Elsevier B.V. Sub-lithospheric diamonds from the Juina-5 and Collier-4 kimberlites and the Machado River alluvial deposit in Brazil have carbon isotopic compositions that co-vary with the oxygen isotopic compositions of their inclusions, which implies that they formed by a mixing process. The proposed model for this mixing process, based on interaction of slab-derived carbonate melt with reduced (carbide- or metal-bearing) ambient mantle, explains these isotopic observations. It is also consistent with the observed trace element chemistries of diamond inclusions from these localities and with the experimental phase relations of carbonated subducted crust. The 18O-enriched nature of the inclusions demonstrates that they incorporate material from crustal protoliths that previously interacted with seawater, thus confirming the subduction-related origin of superdeep diamonds. These samples also provide direct evidence of an isotopically anomalous reservoir in the deep (≥350 km) mantle

The WHO checklist: a global tool to prevent errors in surgery

In this article, we welcome the adoption of the WHO surgical checklist to prevent errors in surgical practice. We highlight the scale of the problem and discuss the adoption of this tool in the UK

Adipocyte-specific protein tyrosine phosphatase 1B deletion increases lipogenesis, adipocyte cell size and is a minor regulator of glucose homeostasis

Peer reviewedPublisher PD

Quantum Computing Without Wavefunctions: Time-Dependent Density Functional Theory for Universal Quantum Computation

We prove that the theorems of TDDFT can be extended to a class of qubit Hamiltonians that are universal for quantum computation. The theorems of TDDFT applied to universal Hamiltonians imply that single-qubit expectation values can be used as the basic variables in quantum computation and information theory, rather than wavefunctions. From a practical standpoint this opens the possibility of approximating observables of interest in quantum computations directly in terms of single-qubit quantities (i.e. as density functionals). Additionally, we also demonstrate that TDDFT provides an exact prescription for simulating universal Hamiltonians with other universal Hamiltonians that have different, and possibly easier-to-realize two-qubit interactions. This establishes the foundations of TDDFT for quantum computation and opens the possibility of developing density functionals for use in quantum algorithms

From apology to compensation: A multi-level taxonomy of trust reparation for highly automated virtual assistants

This paper presents a multi-level taxonomy of reparation levels specifically adapted to virtual assistants in the context of Human-Human-Interaction (HHI) with a specific focus on maintaining trust in the system. This taxonomy ranges from current models of apology to the newly integrated compensation area via a range of case studies specifically developed to address the rising concerns of unsupervised interactions in the context of Virtual Assistants (VA). Based on preliminary research, the author recommends the integration of reparation strategies as a fundamental variable in the ongoing development of VAs, as this element inserts a sense of balance in terms of vulnerability between users and developers to enhance trust in the interactive process. Present and future work is being dedicated to further understand how different contexts may affect integrity in highly automated virtual assistants

Structure of hadron resonances with a nearby zero of the amplitude

We discuss the relation between the analytic structure of the scattering amplitude and the origin of an eigenstate represented by a pole of the amplitude.If the eigenstate is not dynamically generated by the interaction in the channel of interest, the residue of the pole vanishes in the zero coupling limit. Based on the topological nature of the phase of the scattering amplitude, we show that the pole must encounter with the Castillejo-Dalitz-Dyson (CDD) zero in this limit. It is concluded that the dynamical component of the eigenstate is small if a CDD zero exists near the eigenstate pole. We show that the line shape of the resonance is distorted from the Breit-Wigner form as an observable consequence of the nearby CDD zero. Finally, studying the positions of poles and CDD zeros of the KbarN-piSigma amplitude, we discuss the origin of the eigenstates in the Lambda(1405) region.Comment: 7 pages, 3 figures, v2: published versio

Discrepancies between the medical record and the reports of patients with acute coronary syndrome regarding important aspects of the medical history

<p>Abstract</p> <p>Background</p> <p>Many critical treatment decisions are based on the medical history of patients with an acute coronary syndrome (ACS). Discrepancies between the medical history documented by a health professional and the patient's own report may therefore have important health consequences.</p> <p>Methods</p> <p>Medical histories of 117 patients with an ACS were documented. A questionnaire assessing the patient's health history was then completed by 62 eligible patients. Information about 13 health conditions with relevance to ACS management was obtained from the questionnaire and the medical record. Concordance between these two sources and reasons for discordance were identified.</p> <p>Results</p> <p>There was significant variation in agreement, from very poor in angina (kappa < 0) to almost perfect in diabetes (kappa = 0.94). Agreement was substantial in cerebrovascular accident (kappa = 0.76) and hypertension (kappa = 0.73); moderate in cocaine use (kappa = 0.54), smoking (kappa = 0.46), kidney disease (kappa = 0.52) and congestive heart failure (kappa = 0.54); and fair in arrhythmia (kappa = 0.37), myocardial infarction (kappa = 0.31), other cardiovascular diseases (kappa = 0.37) and bronchitis/pneumonia (kappa = 0.31). The odds of agreement was 42% higher among individuals with at least some college education (OR = 1.42; 95% CI, 1.00 - 2.01, p = 0.053). Listing of a condition in medical record but not in the questionnaire was a common cause of discordance.</p> <p>Conclusion</p> <p>Discrepancies in aspects of the medical history may have important effects on the care of ACS patients. Future research focused on identifying the most effective and efficient means to obtain accurate health information may improve ACS patient care quality and safety.</p