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In basaltic volcanic ash recovered from a seamount at 3000 m water depth, we discovered marcasite and pyrite precipitation within cavities that formed by partial to complete dissolution of olivine. In places, these cavities are reminiscent of negative crystal shapes; elsewhere they apparently continue along cracks. In strong contrast, adjacent volcanic glass shows little, if any, evidence for dissolution. The FeS2precipitates were commonly found to be conjoined and planar aggregates, occurring in the center of the voids. Their maximum volume fraction in relation to the void space as determined by 2D and 3D imaging techniques corresponds to the amount of iron released by olivine dissolution. Almost all occurrences of FeS2precipitation are related to Cr-spinel inclusions in the former olivine. We propose that rapid olivine dissolution was initiated by reduced H2S-bearing fluids at olivine grain boundaries or surfaces exposed by cracks. Many of these cracks are connected to spinel grains, where the iron liberated from olivine is mineralized as FeS2, initially facilitated by heterogeneous nucleation. Subsequent pyrite and/or marcasite precipitation occurred as overgrowths on existing FeS2aggregates. The particular chemical environment of low-pH, hydrogen sulfide-bearing fluids may have enhanced olivine dissolution by (1) keeping Fe in solution and (2) sequestering important quantities of Fe as FeS2. The in situ oxidation of ferrous Fe and precipitation of ferric hydroxides at the olivine surface commonly observed in oxic environments were obviously impeded. It would have slowed down olivine dissolution to rates more similar to the dissolution of basaltic glass. We have no direct indication that the process of rapid olivine dissolution was aided by subseafloor life. However, the presence of fibrous structures with small sulfide particles could indicate late colonization of sulfate-reducing bacteria that may add an additional path of iron fixation.

Troctolites are increasingly recognized as a common rock found in association with oceanic core complexes. They are similar to komatiite in composition, and hence troctolite alteration may provide insight into H2production on Early Earth. We investigated the hydrothermal alteration of olivine-rich troctolites in two batch experiments (300 °C, and 400 °C – 40 MPa) by reacting forsteritic olivine and anorthite-rich plagioclase with salt solutions. The alteration process was evaluated based on concomitant fluid samples and solids retrieved upon the termination of the experiments. In both experiments, the initial rock powder was turned into a hard, compact mass through cementation by secondary phases. The heterogeneity of this mass was documented using μ-computed tomography and electron microscopy. Thermodynamic computations were conducted to determine the equilibrium phase assemblages and fluid compositions with increasing reaction turnover.

Current approaches to stratify patients with psychiatric disorders into groups on the basis of violence risk are limited by inconsistency, variable accuracy, and unscalability. To address the need for a scalable and valid tool to assess violence risk in patients with schizophrenia spectrum or bipolar disorder, we describe the derivation of a score based on routinely collected factors and present findings from external validation.

With the increase in the number of risk assessment tools and clinical algorithms in many areas of science and medicine, this Perspective article provides an overview of research findings that can assist in informing the choice of an instrument for practical use. We take the example of violence risk assessment tools in criminal justice and forensic psychiatry, where there are more than 200 such instruments and their use is typically mandated. We outline 10 key questions that researchers, clinicians and other professionals should ask when deciding what tool to use, which are also relevant for public policy and commissioners of services. These questions are based on two elements: research underpinning the external validation, and derivation or development of a particular instrument. We also recommend some guidelines for reporting drawn from consensus guidelines for research in prognostic models.

The exposure of mantle peridotite to water at crustal levels leads to a cascade of interconnected dissolution-precipitation and reduction-oxidation reactions-a process referred to as serpentinization. These reactions have major implications for microbial life through the provision of hydrogen (H2). To simulate incipient serpentinization under well-constrained conditions, we reacted centimeter-sized pieces of uncrushed harzburgite with chemically modified seawater at 300 °C and 35 MPa for ca. 1.5 yr (13 441 h), monitored changes in fluid chemistry over time, and examined the secondary mineralogy at the termination of the experiment. Approximately 4 mol% of the protolith underwent alteration forming serpentine, accessory magnetite, chlorite, and traces of calcite and heazlewoodite. Alteration textures bear remarkable similarities to those found in partially serpentinized abyssal peridotites. Neither brucite nor talc precipitated during the experiment. Given that the starting material contained ~4 times more olivine than orthopyroxene on a molar basis, mass balance requires that dissolution of orthopyroxene was significantly faster than dissolution of olivine. Coupled mass transfer of dissolved Si, Mg, and H+between olivine and orthopyroxene reaction fronts was driven by steep activity gradients and facilitated the precipitation of serpentine. Hydrogen was released in significant amounts throughout the entire experiment; however, the H2release rate decreased with time. Serpentinization consumed water but did not release significant amounts of dissolved species (other than H2) suggesting that incipient hydration reactions involved a volume increase of ~40%. The reduced access of water to fresh olivine surfaces due to filling of fractures and coating of primary minerals with alteration products led to decreased rates of serpentinization and H2release. While this concept might seem at odds with completely serpentinized seafloor peridotites, reaction-driven fracturing offers an intriguing solution to the seemingly self-limiting nature of serpentinization. Indeed, the reacted sample revealed several textural features diagnostic of incipient reaction-driven fracturing. We conclude that fracturing must have far reaching impacts on the rates of serpentinization and H2release in peridotite-hosted hydrothermal systems.

Epilepsy is associated with high rates of premature mortality, but the contribution of psychiatric comorbidity is uncertain. We assessed the prevalence and risks of premature mortality from external causes such as suicide, accidents, and assaults in people with epilepsy with and without psychiatric comorbidity.

Abstract: The bone-eating marine annelid Osedax consumes mainly whale bones on the deep-sea floor, but recent colonization experiments with cow bones and molecular age estimates suggesting a possible Cretaceous origin of Osedax indicate that this worm might be able grow on a wider range of substrates. The suggested Cretaceous origin was thought to imply that Osedax could colonize marine reptile or fish bones, but there is currently no evidence that Osedax consumes bones other than those of mammals. We provide the first evidence that Osedax was, and most likely still is, able to consume non-mammalian bones, namely bird bones. Borings resembling those produced by living Osedax were found in bones of early Oligocene marine flightless diving birds (family Plotopteridae). The species that produced these boreholes had a branching filiform root that grew to a length of at least 3 mm, and lived in densities of up to 40 individuals per square centimeter. The inclusion of bird bones into the diet of Osedax has interesting implications for the recent suggestion of a Cretaceous origin of this worm because marine birds have existed continuously since the Cretaceous. Bird bones could have enabled this worm to survive times in the Earth’s history when large marine vertebrates other than fish were rare, specifically after the disappearance of large marine reptiles at the end-Cretaceous mass extinction event and before the rise of whales in the Eocene.

Classical von Willebrand disease (VWD) type 2A, the most common qualitative defect of VWD, is caused by loss of high-molecular-weight multimers (HMWMs) of von Willebrand factor (VWF). Underlying mutations cluster in the A2 domain of VWF around its cleavage site for ADAMTS13. We investigated the impact of mutations commonly found in patients with VWD type 2A on ADAMTS13-dependent proteolysis of VWF. We used recombinant human ADAMTS13 (rhuADAMTS13) to digest recombinant full-length VWF and a VWF fragment spanning the VWF A1 through A3 domains, harboring 13 different VWD type 2A mutations (C1272S, G1505E, G1505R, S1506L, M1528V, R1569del, R1597W, V1607D, G1609R, I1628T, G1629E, G1631D, and E1638K). With the exception of G1505E and I1628T, all mutations in the VWF A2 domain increased specific proteolysis of VWF independent of the expression level. Proteolytic susceptibility of mutant VWF in vitro closely correlated with the in vivo phenotype in patients. The results imply that increased VWF susceptibility for ADAMTS13 is a constitutive property of classical VWD type 2A, thus explaining the pronounced proteolytic fragments and loss of HMWM seen in multimer analysis in patients.

Molar enthalpies of formation of natural, near end-member tremolite and talc have been calculated from high temperature lead borate drop-solution calorimetry. Using three mutually consistent reaction cycles for each phase, the critical volatile component H2O was treated in fundamentally different ways, namely as the simple “oxide” [i.e., as the enthalpy difference (HTCal- H298.15) only], or as the (OH)-component in both low and high water-content phases, respectively. The molar enthalpies of drop solution of all solid phases participating in the various reaction cycles (brucite, diopside, enstatite, calcite, magnesite, quartz) were independently measured. We corroborate that the dynamic gas flow techniques introduced by Navrotsky et al. (1994) are critically important for very hydrous phases such as brucite, but that this dynamic technique yields the same results as traditional static drop-solution techniques for phases with relatively lower water contents such as tremolite and talc. When these critical differences in H2O behavior are taken into account, it can be shown that drop-solution measurements on tremolite and talc over the last twenty years actually lead to similar and consistent results on the enthalpy of formation of these phases; reported differences are due to incorrect assumptions on the final state of H2O. Our refined values for the enthalpy of formation from the elements for ideal end-member tremolite and talc range from -12299.2 to -12308.9 kJ/mol and -5892.1 to -5900.2 kJ/mol, respectively, depending on the internally consistent data set used for the reaction cycle components. These values are identical within error to the results refined from various phase-equilibrium experiments and show that these two fundamentally different techniques can lead to a consistent picture on the thermodynamic properties of hydrous minerals, a conclusion that has been strongly questioned in the past.

This paper presents studies of samples from different localities of the Garnet-Amphibole-Magnetite (GAM)-Quartzite Member of the Ammonoosuc Volcanics from southern New England, USA. Based on stratigraphic and geochemical evidence, earlier workers interpreted the Ammonoosuc Volcanics as part of a volcanic island-arc complex. As such, these rocks have a highly varied stratigraphy with a wide spectrum of chemical compositions. During subsequent metamorphism, these rocks reached amphibolite-facies conditions (6 kbar and 580-640 °C). Within the Ammonoosuc Volcanics, a finegrained, garnet-, magnetite-, and amphibole-bearing quartzite forms a distinct stratigraphic horizon. The quartzite commonly shows delicate millimeter- to centimeter-thick layering, which is interpreted as an original depositional feature that could have formed by precipitation from solutions enriched in silica, iron, and manganese. Volcanic detritus that was rich in Al, Ca, Mg, and Na could account for the variation in concentration of these elements, which are present along with Fe, Mn, and Si in some laminae of these quartzites.

An increasing number of metrics are used to measure the impact of research papers. Despite being the most commonly used, the 2-year impact factor is limited by a lack of generalisability and comparability, in part due to substantial variation within and between fields. Similar limitations apply to metrics such as citations per paper. New approaches compare a paper's citation count to others in the research area, while others measure social and traditional media impact. However, none of these measures take into account an individual author's contribution to the paper or the number of authors, which we argue are key limitations. The UK's 2014 Research Exercise Framework included a detailed bibliometric analysis comparing 15 selected metrics to a ‘gold standard’ evaluation of almost 150 000 papers by expert panels. We outline the main correlations between the most highly regarded papers by the expert panel in the Psychiatry, Clinical Psychology and Neurology unit and these metrics, most of which were weak to moderate. The strongest correlation was with the SCImago Journal Rank, a variant of the journal impact factor, while the amount of Twitter activity showed no correlation. We suggest that an aggregate measure combining journal metrics, field-standardised citation data and alternative metrics, including weighting or colour-coding of individual papers to account for author contribution, could provide more clarity.

Several letters to the editor are presented in response to articles in previous issues related to opera, including an interview about singer Roberto Alagna, a survey of the opera houses in Berlin, Germany, and a difference between the production of "Turandot" and "Le Grand Macabre" by the English National Opera.