An experimental study of carbonated eclogite at 3.5-5.5 GPa – Implications for silicate and carbonate metasomatism in the cratonic mantle

We have experimentally investigated a K-bearing altered mid-ocean ridge basalt (MORB) composition to which 10% CaCO3 was added (GA1+10%cc), at temperatures of 1050-1400oC and pressures of 3•5-5•5 GPa. Experiments were conducted in piston-cylinder apparatus in Pt-Gr (Pt with inner graphite) and Au-Pd capsules. Sub-solidus assemblages for both sets of experiments contain clinopyroxene, garnet, carbonate, rutile, coesite and K-feldspar. Apatite was observed only in the Pt-Gr experiments. Melting behaviour in experiments using different capsule materials contrasted markedly. Experiments in Pt-Gr capsules showed the silicate solidus to be at temperatures less than 1100oC at 3•5GPa and less than 1050oC at 4•5-5•0 GPa.These are similar (3•5GPa) or lower (4•5-5•0 GPa) temperatures compared with the carbonate solidus (1075-1125oC at 3•5-5•0 GPa). Melts in the Pt-Gr runs evolve with increasing degree of melting from K-rich silicate melts at the lowest degree of melting to carbonate-silicate immiscible liquids and silicate-carbonate melts at intermediate degrees of melting, and finally to silicate melts at the highest degrees of melting. Experiments in Au-Pd capsules were performed only at 5•0GPa. The carbonate solidus is between 1200 and 1225oC (at least 100oC higher than in the experiments in Pt-Gr capsules at the same pressure-temperature conditions).The first melts to be produced are carbonatitic and exhibit increasing SiO2 content with increasing temperature.This contrast in melting behaviour is explained by the relatively rapid diffusion of H through the Pt-Gr capsules, resulting in formation of H2O, and thus dramatically depressing both the silicate and the carbonate solidi in the Pt-Gr experiments compared with those in the Au-Pd experiments. This presumably reflects the lower permeability of Au-Pd to H, resulting in a much lower H2O/CO2 ratio in the Au-Pd encapsulated experiments. The presence of water in the melt was demonstrated by Fourier transform infrared (FTIR) spectroscopic analysis of one Pt-Gr experiment, indicating ~0•5wt % H2O in the bulk composition. Further confirmation that H2O plays such a role in the Pt-Gr experiments was provided by an additional experiment performed in a Au-Pd capsule with ~10 wt % H2Ospecifically added. In this experiment immiscible carbonate and silicate melts were observed. Carbonate- silicate liquid immiscibility is considered to occur as a result of the H2O present in the system. These results can be applied to natural systems in several ways. First, the presence of a small amount of either silicate melt or H2O-fluid in the system will act as a ‘flux’, depressing the carbonate solidus to much lower temperatures than inanhydrous systems. Second, the full trend in melt evolution from silicate-rich to carbonate-rich melts, which is also observed in inclusions in diamonds, can be explained by melting of K- and CO2-bearing, water-undersaturated MORB compositions. In cratonic environments low-degree silicate and immiscible silicate and carbonate melts will metasomatize the overlying mantle in different ways, producing, in the first instance, Si enrichment and crystallization of additional orthopyroxene, phlogopite, pyrope-rich garnet and consuming olivine, and, in the second case, carbonate metasomatism, with additional magnesite-dolomite, clinopyroxene and apatite. Both metasomatic styles have been described in natural peridotite xenoliths from the cratonic lithosphere

Modulation of emotional appraisal by false physiological feedback during fMRI

BACKGROUND James and Lange proposed that emotions are the perception of physiological reactions. Two-level theories of emotion extend this model to suggest that cognitive interpretations of physiological changes shape self-reported emotions. Correspondingly false physiological feedback of evoked or tonic bodily responses can alter emotional attributions. Moreover, anxiety states are proposed to arise from detection of mismatch between actual and anticipated states of physiological arousal. However, the neural underpinnings of these phenomena previously have not been examined. METHODOLOGY/PRINCIPAL FINDINGS We undertook a functional brain imaging (fMRI) experiment to investigate how both primary and second-order levels of physiological (viscerosensory) representation impact on the processing of external emotional cues. 12 participants were scanned while judging face stimuli during both exercise and non-exercise conditions in the context of true and false auditory feedback of tonic heart rate. We observed that the perceived emotional intensity/salience of neutral faces was enhanced by false feedback of increased heart rate. Regional changes in neural activity corresponding to this behavioural interaction were observed within included right anterior insula, bilateral mid insula, and amygdala. In addition, right anterior insula activity was enhanced during by asynchronous relative to synchronous cardiac feedback even with no change in perceived or actual heart rate suggesting this region serves as a comparator to detect physiological mismatches. Finally, BOLD activity within right anterior insula and amygdala predicted the corresponding changes in perceived intensity ratings at both a group and an individual level. CONCLUSIONS/SIGNIFICANCE Our findings identify the neural substrates supporting behavioural effects of false physiological feedback, and highlight mechanisms that underlie subjective anxiety states, including the importance of the right anterior insula in guiding second-order "cognitive" representations of bodily arousal state

Modulation of emotional appraisal by false physiological feedback during fMRI

BACKGROUND James and Lange proposed that emotions are the perception of physiological reactions. Two-level theories of emotion extend this model to suggest that cognitive interpretations of physiological changes shape self-reported emotions. Correspondingly false physiological feedback of evoked or tonic bodily responses can alter emotional attributions. Moreover, anxiety states are proposed to arise from detection of mismatch between actual and anticipated states of physiological arousal. However, the neural underpinnings of these phenomena previously have not been examined. METHODOLOGY/PRINCIPAL FINDINGS We undertook a functional brain imaging (fMRI) experiment to investigate how both primary and second-order levels of physiological (viscerosensory) representation impact on the processing of external emotional cues. 12 participants were scanned while judging face stimuli during both exercise and non-exercise conditions in the context of true and false auditory feedback of tonic heart rate. We observed that the perceived emotional intensity/salience of neutral faces was enhanced by false feedback of increased heart rate. Regional changes in neural activity corresponding to this behavioural interaction were observed within included right anterior insula, bilateral mid insula, and amygdala. In addition, right anterior insula activity was enhanced during by asynchronous relative to synchronous cardiac feedback even with no change in perceived or actual heart rate suggesting this region serves as a comparator to detect physiological mismatches. Finally, BOLD activity within right anterior insula and amygdala predicted the corresponding changes in perceived intensity ratings at both a group and an individual level. CONCLUSIONS/SIGNIFICANCE Our findings identify the neural substrates supporting behavioural effects of false physiological feedback, and highlight mechanisms that underlie subjective anxiety states, including the importance of the right anterior insula in guiding second-order "cognitive" representations of bodily arousal state

Body Size Measurements as Predictors of Type 2 Diabetes in Aboriginal People

OBJECTIVE: To investigate waist circumference, waist-to-hip ratio, body mass index (BMI), weight and hip circumference as risk factors for type 2 diabetes in Aboriginal Australians. DESIGN: Community-based cross-sectional study. SUBJECTS: In total, 915 Australian Aboriginal adults (age: 18-74 y) from a remote Aboriginal community in the Northern Territory of Australia. MEASUREMENTS: Body size measurements included waist circumference, waist-to-hip ratio, BMI, weight and hip circumference. Diabetes status was determined according to medical history and fasting and 2-h postload plasma glucose values. Logistic regression was used to calculate odds ratio for diabetes associated with 1 standard deviation (s.d.) increase in a body size measurement. The areas under the ROC curves of five body size measurements were calculated and compared. RESULTS: Risk of diabetes increased with increasing levels of body size. ORs (95% CI) for diabetes with adjustment for age and sex were 2.16 (1.75, 2.66), 1.80 (1.49, 2.17), 1.41 (1.17, 1.71), 1.81 (1.51, 2.19) and 1.84 (1.50, 2.24) associated with 1 s.d. increase in waist circumference, BMI, weight, waist-to-hip ratio, and hip circumference, respectively. The area under the ROC curve for waist circumference was significantly higher than those for other measurements. CONCLUSION: Waist circumference is the best body size measurement in predicting diabetes in Aboriginal people

Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector

The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV

Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT

The continuum of spreading depolarizations in acute cortical lesion development: Examining Leão's legacy.

A modern understanding of how cerebral cortical lesions develop after acute brain injury is based on Aristides Leão's historic discoveries of spreading depression and asphyxial/anoxic depolarization. Treated as separate entities for decades, we now appreciate that these events define a continuum of spreading mass depolarizations, a concept that is central to understanding their pathologic effects. Within minutes of acute severe ischemia, the onset of persistent depolarization triggers the breakdown of ion homeostasis and development of cytotoxic edema. These persistent changes are diagnosed as diffusion restriction in magnetic resonance imaging and define the ischemic core. In delayed lesion growth, transient spreading depolarizations arise spontaneously in the ischemic penumbra and induce further persistent depolarization and excitotoxic damage, progressively expanding the ischemic core. The causal role of these waves in lesion development has been proven by real-time monitoring of electrophysiology, blood flow, and cytotoxic edema. The spreading depolarization continuum further applies to other models of acute cortical lesions, suggesting that it is a universal principle of cortical lesion development. These pathophysiologic concepts establish a working hypothesis for translation to human disease, where complex patterns of depolarizations are observed in acute brain injury and appear to mediate and signal ongoing secondary damage

A call for transparent reporting to optimize the predictive value of preclinical research

The US National Institute of Neurological Disorders and Stroke convened major stakeholders in June 2012 to discuss how to improve the methodological reporting of animal studies in grant applications and publications. The main workshop recommendation is that at a minimum studies should report on sample-size estimation, whether and how animals were randomized, whether investigators were blind to the treatment, and the handling of data. We recognize that achieving a meaningful improvement in the quality of reporting will require a concerted effort by investigators, reviewers, funding agencies and journal editors. Requiring better reporting of animal studies will raise awareness of the importance of rigorous study design to accelerate scientific progress

Search for R-parity-violating supersymmetry in events with four or more leptons in sqrt(s) =7 TeV pp collisions with the ATLAS detector

A search for new phenomena in final states with four or more leptons (electrons or muons) is presented. The analysis is based on 4.7 fb−1 of $\sqrt{s}=7\;\mathrm{TeV}$ proton-proton collisions delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in two signal regions: one that requires moderate values of missing transverse momentum and another that requires large effective mass. The results are interpreted in a simplified model of R-parity-violating supersymmetry in which a 95% CL exclusion region is set for charged wino masses up to 540 GeV. In an R-parity-violating MSUGRA/CMSSM model, values of m 1/2 up to 820 GeV are excluded for 10 < tan β < 40

Measurement of the cross-section of high transverse momentum vector bosons reconstructed as single jets and studies of jet substructure in pp collisions at √s = 7 TeV with the ATLAS detector

This paper presents a measurement of the cross-section for high transverse momentum W and Z bosons produced in pp collisions and decaying to all-hadronic final states. The data used in the analysis were recorded by the ATLAS detector at the CERN Large Hadron Collider at a centre-of-mass energy of √s = 7 TeV;{\rm Te}{\rm V}$and correspond to an integrated luminosity of$4.6\;{\rm f}{{{\rm b}}^{-1}}$. The measurement is performed by reconstructing the boosted W or Z bosons in single jets. The reconstructed jet mass is used to identify the W and Z bosons, and a jet substructure method based on energy cluster information in the jet centre-of-mass frame is used to suppress the large multi-jet background. The cross-section for events with a hadronically decaying W or Z boson, with transverse momentum${{p}_{{\rm T}}}\gt 320\;{\rm Ge}{\rm V}$and pseudorapidity$|\eta |\lt 1.9$, is measured to be${{\sigma }_{W+Z}}=8.5\pm 1.7$ pb and is compared to next-to-leading-order calculations. The selected events are further used to study jet grooming techniques