1,964 research outputs found

    Investigating the Dynamics and Density Evolution of Returning Plasma Blobs from the 2011 June 7 Eruption

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    This work examines infalling matter following an enormous Coronal Mass Ejection (CME) on 2011 June 7. The material formed discrete concentrations, or blobs, in the corona and fell back to the surface, appearing as dark clouds against the bright corona. In this work we examined the density and dynamic evolution of these blobs in order to formally assess the intriguing morphology displayed throughout their descent. The blobs were studied in five wavelengths (94, 131, 171, 193 and 211 \AA) using the Solar Dynamics Observatory Atmospheric Imaging Assembly (SDO/AIA), comparing background emission to attenuated emission as a function of wavelength to calculate column densities across the descent of four separate blobs. We found the material to have a column density of hydrogen of approximately 2 ×\times 1019^{19} cm−2^{-2}, which is comparable with typical pre-eruption filament column densities. Repeated splitting of the returning material is seen in a manner consistent with the Rayleigh-Taylor instability. Furthermore, the observed distribution of density and its evolution are also a signature of this instability. By approximating the three-dimensional geometry (with data from STEREO-A), volumetric densities were found to be approximately 2 ×\times 10−14^{-14} g cm−3^{-3}, and this, along with observed dominant length-scales of the instability, was used to infer a magnetic field of the order 1 G associated with the descending blobs.Comment: 9 pages, 13 figures, accepted for publication in Ap

    Leadership for change

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    This edited volume reveals how the journey of transformation at the University of the Free State (UFS) became interwoven with student leadership development and global learning. The UFS initiated two intersecting co-curricular programmes, namely, the First-Year Leadership for Change (F1L4C) programme in 2010; and the triennial Global Leadership Summit (GLS) in 2012. Although these programmes changed over time, their core focus remained to be the development of transformational student leaders through the creation of global learning spaces. From its inception in 2010 to the last GLS in 2018, the UFS global learning project involved 780 students and 259 staff members from 109 institutions, across four continents. The goal of this edited volume is to create a deeper understanding of how the UFS F1L4C and GLS programmes enhanced student leadership development through global learning, especially in the context of higher education transformation

    Leadership for change

    Get PDF
    This edited volume reveals how the journey of transformation at the University of the Free State (UFS) became interwoven with student leadership development and global learning. The UFS initiated two intersecting co-curricular programmes, namely, the First-Year Leadership for Change (F1L4C) programme in 2010; and the triennial Global Leadership Summit (GLS) in 2012. Although these programmes changed over time, their core focus remained to be the development of transformational student leaders through the creation of global learning spaces. From its inception in 2010 to the last GLS in 2018, the UFS global learning project involved 780 students and 259 staff members from 109 institutions, across four continents. The goal of this edited volume is to create a deeper understanding of how the UFS F1L4C and GLS programmes enhanced student leadership development through global learning, especially in the context of higher education transformation

    Are environmental factors for atopic eczema in ISAAC Phase Three due to reverse causation?

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    Some previously described environmental associations for atopic eczema (AE) may be due to reverse causation. We explored the role of reverse causation by comparing individual- and school-level results for multiple AE risk factors. ISAAC Phase Three surveyed children within schools (the sampling unit) on AE symptoms and potential risk factors. We assessed the effect of these risk factors on AE symptoms using mixed-effect logistic regression models, first with individual-level exposure data and second with school-level exposure prevalence. 546,348 children from 53 countries were included. At age 6-7 the strongest individual-level associations were with current paracetamol use (odds ratio=1.45, 95% confidence interval 1.37-1.54), which persisted at school-level (1.55, 1.10-2.21), antibiotics (1.41, 1.34-1.48) and early life paracetamol use (1.28, 1.21-1.36) with the former persisting at school-level while the latter was no longer observed (1.35, 1.00-1.82 and 0.94, 0.69-1.28 respectively). At age 13-14 the strongest associations at individual-level were with current paracetamol use (1.57, 1.51-1.63) and open-fire cooking (1.46, 1.33-1.62); both were stronger at school-level (2.57, 1.84-3.59 and 2.38, 1.52-3.73 respectively). Association with exposure to heavy traffic (1.31, 1.27-1.36) also persisted at school-level (1.40, 1.07-1.82). Most individual- and school level effects were consistent tending to exclude reverse causation

    Are environmental factors for atopic eczema in ISAAC Phase Three due to reverse causation?

    Get PDF
    Some previously described environmental associations for atopic eczema (AE) may be due to reverse causation. We explored the role of reverse causation by comparing individual- and school-level results for multiple AE risk factors. ISAAC Phase Three surveyed children within schools (the sampling unit) on AE symptoms and potential risk factors. We assessed the effect of these risk factors on AE symptoms using mixed-effect logistic regression models, first with individual-level exposure data and second with school-level exposure prevalence. 546,348 children from 53 countries were included. At age 6-7 the strongest individual-level associations were with current paracetamol use (odds ratio=1.45, 95% confidence interval 1.37-1.54), which persisted at school-level (1.55, 1.10-2.21), antibiotics (1.41, 1.34-1.48) and early life paracetamol use (1.28, 1.21-1.36) with the former persisting at school-level while the latter was no longer observed (1.35, 1.00-1.82 and 0.94, 0.69-1.28 respectively). At age 13-14 the strongest associations at individual-level were with current paracetamol use (1.57, 1.51-1.63) and open-fire cooking (1.46, 1.33-1.62); both were stronger at school-level (2.57, 1.84-3.59 and 2.38, 1.52-3.73 respectively). Association with exposure to heavy traffic (1.31, 1.27-1.36) also persisted at school-level (1.40, 1.07-1.82). Most individual- and school level effects were consistent tending to exclude reverse causation

    Effects of High Flavanol Dark Chocolate on Cardiovascular Function and Platelet Aggregation.

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    Regular consumption of chocolate and cocoa products has been linked to reduced cardiovascular mortality. This study compared the effects of high flavanol dark chocolate (HFDC; 1064mg flavanols/day for 6 weeks) and low flavanol dark chocolate (LFDC; 88mg flavanols/day for 6 weeks) on blood pressure, heart rate, vascular function and platelet aggregation in men with pre-hypertension or mild hypertension. Vascular function was assessed by pulse wave analysis using radial artery applanation tonometry in combination with inhaled salbutamol (0.4 mg) to assess changes due to endothelium-dependent vasodilatation. HFDC did not significantly reduce blood pressure compared to baseline or LFDC. Heart rate was increased by LFDC compared to baseline, but not by HFDC. Vascular responses to salbutamol tended to be greater after HFDC. Platelet aggregation induced by collagen or the thromboxane analogue U46619 was unchanged after LFDC or HFDC, whereas both chocolates reduced responses to ADP and the thrombin receptor activator peptide, SFLLRNamide (TRAP6), relative to baseline. Pre-incubation of platelets with theobromine also attenuated platelet aggregation induced by ADP or TRAP6. We conclude that consumption of HFDC confers modest improvements in cardiovascular function. Platelet aggregation is modulated by a flavanol-independent mechanism that is likely due to theobromine.This study was supported by a grant (to R. Corder) from Barry Callebaut Belgium N
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