540 research outputs found

    A small-scale dynamo in feedback-dominated galaxies - III. Cosmological simulations

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    Magnetic fields are widely observed in the Universe in virtually all astrophysical objects, from individual stars to entire galaxies, even in the intergalactic medium, but their specific generation has long been debated. Due to the development of more realistic models of galaxy formation, viable scenarios are emerging to explain cosmic magnetism, thanks to both deeper observations and more efficient and accurate computer simulations. We present here a new cosmological high-resolution zoom-in magnetohydrodynamic (MHD) simulation, using the adaptive mesh refinement (AMR) technique, of a dwarf galaxy with an initially weak and uniform magnetic seed field that is amplified by a small-scale dynamo driven by supernova-induced turbulence. As first structures form from the gravitational collapse of small density fluctuations, the frozen-in magnetic field separates from the cosmic expansion and grows through compression. In a second step, star formation sets in and establishes a strong galactic fountain, self-regulated by supernova explosions. Inside the galaxy, the interstellar medium becomes highly turbulent, dominated by strong supersonic shocks, as demonstrated by the spectral analysis of the gas kinetic energy. In this turbulent environment, the magnetic field is quickly amplified via a small-scale dynamo process and is finally carried out into the circumgalactic medium by a galactic wind. This realistic cosmological simulation explains how initially weak magnetic seed fields can be amplified quickly in early, feedback-dominated galaxies, and predicts, as a consequence of the small scale dynamo process, that high-redshift magnetic fields are likely to be dominated by their small scale components.Comment: 6 pages, 6 figures, submitted to MNRA

    Authorizing medical cannabis for children.

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    Design and conduct of early phase drug studies in children: challenges and opportunities

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    It has historically been very difficult to conduct early phase drug studies in children for a number of reasons related to ethics, acceptability, rarity, standardization, end points, safety, dosing and feasibility. Over the past decade there have been a number of developments including novel clinical trial design, in silico pharmacology and microdosing that have significantly enhanced the ability of investigators to conduct early phase drug studies in children. While the evolution of drug therapy is creating a series of new challenges, there has never been a better time for conducting drug studies in children

    Armed conflict and child health

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    Armed conflict has a major impact on child health throughout the world. One in six children worldwide lives in an area of armed conflict and civilians are more likely to die than soldiers as a result of the conflict. In stark contrast to the effect on children, the international arms trade results in huge profi ts for the large corporations involved in producing arms, weapons and munitions. Armed confl ict is not inevitable but is an important health issue that should be prevented

    Baby boy blue - Why is this newborn lethargic?

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    Adverse drug reactions

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    A supplementary home dose of oral ondansetron given in anticipation of recurrent emesis in paediatric acute gastroenteritis

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    Ondansetron is a useful adjunct for the treatment of acute gastroenteritis in the paediatric ED. The use of ondansetron is associated with many benefits including decreased emesis, decreased need for intravenous fluids, decreased rate of admission, decreased length of stay, decreased revisit rates and increased cost savings (15-18). There may be value in giving patients a second as-needed home dose of ondansetron as part of ED discharge planning, with the appropriate patient education, in anticipation of recurrent emesis. This practice may further reduce ED revisit rates and also prevent morbidity and hospitalization associated with severe dehydration for patients who do eventually return to the ED, especially those in rural communities where timely treatment and access to an ED is difficult. The decision to dispense ondansetron should be made clinically by the ED physician for patients who have failed ORT whose symptoms are predominantly emesis as opposed to diarrhea, and when the discharging physician is reasonably certain of a diagnosis of acute gastroenteritis and not something more sinister. There is currently no consensus on the role of ED-provided ondansetron for out-of-hospital use for paediatric patients with acute gastroenteritis. Future studies are needed to determine the potential impact on morbidity and the health care economy. ©2014 Pulsus Group Inc. All rights reserved

    Key potentially inappropriate drugs in pediatrics: The kids list

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    Paediatric pharmacotherapy and drug regulation: Moving past the therapeutic orphan

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    The development of specific drug therapy for children was a paradigm-changing event that transformed paediatric medical practice. However, a series of tragedies involving drug treatment for children resulted in a gap developing between drug regulation and practice, with the majority of drugs used in child healthcare being used off-label, rendering children therapeutic orphans. Over the past two decades changes in drug regulation led by the US Food and Drug Administration and followed by the European Union\u27s European Medicines Agency have led to substantial changes in how new drugs with potential use in children are studied and labelled. While these changes have substantially improved labelling for new drugs, there has been much less progress with older drugs. Although the unique challenges of conducting clinical research in children have been addressed by novel clinical trial designs, many of these innovations have not been translated into approaches accepted for the drug approval process. The regulations applying to the need for paediatric studies currently are only applicable in the United States and the European Union, and there is less impetus for paediatric labelling in other jurisdictions. This impacts on a number of issues beyond labelling, including the availability of child-friendly formulations. Finally, the impact of Brexit on paediatric drug studies in the UK remains unclear and is subject to ongoing negotiations between the UK government and the European Union
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