2,583 research outputs found

    Iron force constants of bridgmanite at high pressure: Implications for iron isotope fractionation in the deep mantle

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    The isotopic compositions of iron in major mantle minerals may record chemical exchange between deep-Earth reservoirs as a result of early differentiation and ongoing plate tectonics processes. Bridgmanite (Bdg), the most abundant mineral in the Earth’s lower mantle, can incorporate not only Al but also Fe with different oxidation states and spin states, which in turn can influence the distribution of Fe isotopes between Bdg and ferropericlase (Fp) and between the lower mantle and the core. In this study, we combined first-principles calculations with high-pressure nuclear resonant inelastic X-ray scattering measurements to evaluate the effects of Fe site occupancy, valence, and spin states at lower-mantle conditions on the reduced Fe partition function ratio (β-factor) of Bdg. Our results show that the spin transition of octahedral-site (B-site) Fe3+ in Bdg under mid-lower-mantle conditions generates a +0.09‰ increase in its β-factor, which is the most significant effect compared to Fe site occupancy and valence. Fe2+-bearing Bdg varieties have smaller β-factors relative to Fe3+-bearing varieties, especially those containing B-site Fe3+. Our models suggest that Fe isotopic fractionation between Bdg and Fp is only significant in the lowermost mantle due to the occurrence of low-spin Fe2+ in Fp. Assuming early segregation of an iron core from a deep magma ocean, we find that neither core formation nor magma ocean crystallization would have resulted in resolvable Fe isotope fractionation. In contrast, Fe isotopic fractionation between low-spin Fe3+-bearing Bdg/Fe2+-bearing Fp and metallic iron at the core-mantle boundary may have enriched the lowermost mantle in heavy Fe isotopes by up to +0.20‰

    Quantum-inspired interferometry with chirped laser pulses

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    We introduce and implement an interferometric technique based on chirped femtosecond laser pulses and nonlinear optics. The interference manifests as a high-visibility (> 85%) phase-insensitive dip in the intensity of an optical beam when the two interferometer arms are equal to within the coherence length of the light. This signature is unique in classical interferometry, but is a direct analogue to Hong-Ou-Mandel quantum interference. Our technique exhibits all the metrological advantages of the quantum interferometer, but with signals at least 10^7 times greater. In particular we demonstrate enhanced resolution, robustness against loss, and automatic dispersion cancellation. Our interferometer offers significant advantages over previous technologies, both quantum and classical, in precision time delay measurements and biomedical imaging.Comment: 6 pages, 4 figure

    Prenatal Transfer of Gut Bacteria in Rock Pigeon

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    Vertebrates evolved in concert with bacteria and have developed essential mutualistic relationships. Gut bacteria are vital for the postnatal development of most organs and the immune and metabolic systems and may likewise play a role during prenatal development. Prenatal transfer of gut bacteria is shown in four mammalian species, including humans. For the 92% of the vertebrates that are oviparous, prenatal transfer is debated, but it has been demonstrated in domestic chicken. We hypothesize that also non-domestic birds can prenatally transmit gut bacteria. We investigated this in medium-sized Rock pigeon (Columba livia), ensuring neonates producing fair-sized first faeces. The first faeces of 21 neonate rock pigeons hatched in an incubator, contained a microbiome (bacterial community) the composition of which resembled the cloacal microbiome of females sampled from the same population (N = 5) as indicated by multiple shared phyla, orders, families, and genera. Neonates and females shared 16.1% of the total number of OTUs present (2881), and neonates shared 45.5% of their core microbiome with females. In contrast, the five females shared only 0.3% of the 1030 female OTUs present. These findings suggest that prenatal gut bacterial transfer may occur in birds. Our results support the hypothesis that gut bacteria may be important for prenatal development and present a heritability pathway of gut bacteria in vertebrates

    Contrast-enhanced whole-heart coronary MRA at 3.0T for the evaluation of cardiac venous anatomy

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    This study was designed to evaluate the value of contrast-enhanced whole-heart coronary MRA (CMRA) at 3.0T in depicting the cardiac venous anatomy. In cardiac resynchronization therapy (CRT), left ventricular (LV) pacing is achieved by positioning the LV lead in one of the tributaries of the coronary sinus (CS). Pre-implantation knowledge of the venous anatomy may help determine whether transvenous LV lead placement for CRT is feasible. Images of 51 subjects undergoing contrast-enhanced whole-heart CMRA at 3.0T were retrospectively analyzed. Data acquisition was performed using electrocardiography-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence. A 32-element cardiac coil was used for data acquisition. The visibility of the cardiac veins was graded visually using a 4-point scale (1: poor–4: excellent). The paired Student t test was used to evaluate differences in diameters of the ostium of the CS in anteroposterior and superoinferior direction. The cardiac veins were finally evaluated in 48 subjects with three anatomic variations. The diameter of the CS ostium in the superoinferior direction (1.13 ± 0.26 cm) was larger than in the anteroposterior direction (0.82 ± 0.19 cm) (P < 0.05). The mean visibility score of CS, posterior interventricular vein, posterior vein of the left ventricle, left marginal vein, and anterior interventricular vein was 4.0 ± 0.0, 3.4 ± 0.5, 3.4 ± 0.5, 3.0 ± 0.8, and 3.3 ± 0.5, respectively. In conclusion, contrast-enhanced whole-heart CMRA at 3.0T can depict the normal and variant cardiac venous anatomy

    Improving the use of research evidence in guideline development: 11. Incorporating considerations of cost-effectiveness, affordability and resource implications

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    BACKGROUND: The World Health Organization (WHO), like many other organisations around the world, has recognised the need to use more rigorous processes to ensure that health care recommendations are informed by the best available research evidence. This is the 11(th )of a series of 16 reviews that have been prepared as background for advice from the WHO Advisory Committee on Health Research to WHO on how to achieve this. OBJECTIVES: We reviewed the literature on incorporating considerations of cost-effectiveness, affordability and resource implications in guidelines and recommendations. METHODS: We searched PubMed and three databases of methodological studies for existing systematic reviews and relevant methodological research. We did not conduct systematic reviews ourselves. Our conclusions are based on the available evidence, consideration of what WHO and other organisations are doing and logical arguments. KEY QUESTIONS AND ANSWERS: When is it important to incorporate cost-effectiveness, resource implications and affordability considerations in WHO guidelines (which topics)? • For cost-effectiveness: The need for cost/effectiveness information should be dictated by the specific question, of which several may be addressed in a single guideline. It is proposed that the indications for undertaking a cost-effectiveness analysis (CEA) could be a starting point for determining which recommendation(s) in the guideline would benefit from such analysis. • For resource implications/affordability: The resource implications of each individual recommendation need to be considered when implementation issues are being discussed. How can cost-effectiveness, resource implications and affordability be explicitly taken into account in WHO guidelines? • For cost-effectiveness: ∘ If data are available, the ideal time to consider cost-effectiveness is during the evidence gathering and synthesizing stage. However, because of the inconsistent availability of CEAs and the procedural difficulty associated with adjusting results from different CEAs to make them comparable, it is also possible for cost-effectiveness to be considered during the stage of developing recommendations. ∘ Depending on the quantity and quality and relevance of the data available, such data can be considered in a qualitative way or in a quantitative way, ranging from a listing of the costs to a modelling exercise. At the very least, a qualitative approach like a commentary outlining the economic issues that need to be considered is necessary. If a quantitative approach is to be used, the full model should be transparent and comprehensive. • For resource implications/affordability: ∘ Resource implications, including health system changes, for each recommendation in a WHO guideline should be explored. At the minimum, a qualitative description that can serve as a gross indicator of the amount of resources needed, relative to current practice, should be provided. How does one provide guidance in contextualizing guideline recommendations at the country level based on considerations of cost-effectiveness, resource implications and affordability? • All models should be made available and ideally are designed to allow for analysts to make changes in key parameters and reapply results in their own country. • In the global guidelines, scenarios and extensive sensitivity/uncertainty analysis can be applied. Resource implications for WHO • From the above, it is clear that guidelines development groups will need a health economist. There is need to ensure that this is included in the budget for guidelines and that there is in-house support for this as well

    Non-perturbative computation of double inclusive gluon production in the Glasma

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    The near-side ridge observed in A+A collisions at RHIC has been described as arising from the radial flow of Glasma flux tubes formed at very early times in the collisions. We investigate the viability of this scenario by performing a non-perturbative numerical computation of double inclusive gluon production in the Glasma. Our results support the conjecture that the range of transverse color screening of correlations determining the size of the flux tubes is a semi-hard scale, albeit with non-trivial structure. We discuss our results in the context of ridge correlations in the RHIC heavy ion experiments.Comment: 25 pages, 11 figures, uses JHEP3.cls V2: small clarifications, published in JHE

    Expressions of glutathione S-transferase alpha, mu, and pi in brains of medically intractable epileptic patients

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    <p>Abstract</p> <p>Background</p> <p>Glutathione S-transferases (GSTs) play an important role in metabolizing anti-epileptic drugs (AEDs) in liver. Expressions of GSTs in brain, which may result in poor efficacy of AEDs, have not been well studied. Using clinical cortex specimen from 32 intractable epileptic subjects and 8 non-epileptic controls, the present study investigated the correlation between GSTs and intractable epilepsy.</p> <p>Results</p> <p>Three different GST isoforms (α, μ, and π) were detected with immunohistochemistry. GST-α expression was not seen in any cortex specimens. Sixty three percent (63%) of control and 53% of intractible epileptic specimens showed GST-μ immunoreactivity. No significant difference in intensity of GST-μ staining was observed between these two groups. GST-π expression was found in endothelial cells and glial cells/astrocytes. Fifty percent (50%) of the control patients and 66% of the epileptic patients were GST-π positive. The grading of epileptic patients was significantly higher than that of control patients (<it>p </it>< 0.01).</p> <p>Conclusion</p> <p>High levels of GST-π in endothelial cells and glial cells/astrocyte correlate to medical intractable epilepsy, suggesting that GST-π contributes to resistance to AED treatment.</p

    Effectiveness of disinfection with alcohol 70% (w/v) of contaminated surfaces not previously cleaned

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    OBJECTIVE: To evaluate the disinfectant effectiveness of alcohol 70% (w/v) using friction, without previous cleaning, on work surfaces, as a concurrent disinfecting procedure in Health Services. METHOD: An experimental, randomized and single-blinded laboratory study was undertaken. The samples were enamelled surfaces, intentionally contaminated with Serratia marcescens microorganisms ATCC 14756 106 CFU/mL with 10% of human saliva added, and were submitted to the procedure of disinfection WITHOUT previous cleaning. The results were compared to disinfection preceded by cleaning. RESULTS: There was a reduction of six logarithms of the initial microbial population, equal in the groups WITH and WITHOUT previous cleaning (p=0.440) and a residual microbial load ≤ 102 CFU. CONCLUSION: The research demonstrated the acceptability of the practice evaluated, bringing an important response to the area of health, in particular to Nursing, which most undertakes procedures of concurrent cleaning /disinfecting of these work surfaces
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