7,187 research outputs found

    Post-aragonite phases of CaCO3_{3} at lower mantle pressures

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    The stability, structure and properties of carbonate minerals at lower mantle conditions has significant impact on our understanding of the global carbon cycle and the composition of the interior of the Earth. In recent years, there has been significant interest in the behavior of carbonates at lower mantle conditions, specifically in their carbon hybridization, which has relevance for the storage of carbon within the deep mantle. Using high-pressure synchrotron X-ray diffraction in a diamond anvil cell coupled with direct laser heating of CaCO3_{3} using a CO2_{2} laser, we identify a crystalline phase of the material above 40 GPa - corresponding to a lower mantle depth of around 1,000 km - which has first been predicted by \textit{ab initio} structure predictions. The observed sp2sp^{2} carbon hybridized species at 40 GPa is monoclinic with P21/cP2_{1}/c symmetry and is stable up to 50 GPa, above which it transforms into a structure which cannot be indexed by existing known phases. A combination of \textit{ab initio} random structure search (AIRSS) and quasi-harmonic approximation (QHA) calculations are used to re-explore the relative phase stabilities of the rich phase diagram of CaCO3_{3}. Nudged elastic band (NEB) calculations are used to investigate the reaction mechanisms between relevant crystal phases of CaCO3_{3} and we postulate that the mineral is capable of undergoing sp2sp^{2}-sp3sp^{3} hybridization change purely in the P21/cP2_{1}/c structure - forgoing the accepted post-aragonite PmmnPmmn structure.Comment: 12 pages, 8 figure

    Solar flares and their associated processes

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    The evolution of the solar neutrino flux which is described by the wave function ΨT=(νeL,νXL,νeL,νXL)\Psi^T=(\nu_{eL},\nu_{XL}, \overline{\nu}_{eL}, \overline{\nu}_{XL}) is examined. Our treatment of the problem holds for any standard model (SM) extensions possessing nonzero dipole magnetic and anapole moments. When the solar neutrino flux moves through the solar flare (SF) region in the preflare period, then it undergoes the additional (compared with the SM) resonance conversions. As a result, the weakening the electron neutrinos flux takes place. On the other hand, existence of the additional resonances lead to appearance of the νeL\overline{\nu}_{eL} and νXL\overline{\nu}_{XL} neutrinos that could be detected by the terrestrial detectors. The hypothesis of the νe\nu_e-induced β\beta-decays is also discussed. According to it, before the large SF, decreasing the β\beta-decay rate for some elements takes place. The possible influence of the electron antineutrino flux produced in the superflares on the regime of the hypothetical georeactor is considered.Comment: 11 pages. arXiv admin note: text overlap with arXiv:hep-ph/0401221 by other author

    Learning from people with long-term conditions: new insights for governance in primary health care

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    Internationally, system-wide changes to the structures and systems governing health care aim to improve outcomes for patients, quality of care and access to services. The introduction of top-down centrally driven solutions to governance of health care, at the same time as increasing policy emphasis on greater ‘bottom up’ patient and public involvement in all aspects of health care, has set up complex tensions for policy implementation and health care practice. This paper explores the interplay of these agendas in the context of changes in primary health care services provided by the National Health Service (NHS) in England. Specifically, it looks at an example of service user involvement in a study (the PEGI study) of professional response to changes in the governance and incentives in the care of people with long-term conditions. This qualitative study was conducted in three Primary Care Trust sites in England. Service users influenced and guided the study throughout. In-depth interviews with 56 health and social care professionals engaged in the development of local policies and the delivery of care for people with complex long-term illness drew on vignettes developed by 32 members from three Service User Reference Groups (SURG). Themes generated by the cross case analysis were validated through these SURG groups. The findings presented here focus on four themes about risk and comparison of professionals’/service users’ perspectives of the issues: managing risks/consistent support, the risks of letting go/feeling in control, professionalism/helping people to help themselves, and managing expectations/professionals losing out. Service user involvement added value by: validating understandings of governance, framing debates to focus on what matters at the point of care, and enabling perspective sharing and interaction. We suggest that more collaborative forms of governance in health care, that take account of service user perspectives and enable interaction with professional groups, could help to validate processes of quality assurance and provide motivation for continuous quality improvement. We offer a model for ‘opening up’ collaborative projects to evaluation and appraisal and a process for critical reflection of the interrelationships between the PEGI study context, researcher issues, methods/approach and outcomes/impact of service user involvement

    Synthesis of novel monomers containing the trifluorovinylidene group and the cyanato group and polymers thereof

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    Novel hybrid monomers containing both the aryltrifluorovyinyloxyether-group (TFVE-group) and the cyanato-group, their synthesis, and the synthesis of polymers made from these new hybrid monomers are disclosed

    Can Protostellar Jets Drive Supersonic Turbulence in Molecular Clouds?

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    Jets and outflows from young stellar objects are proposed candidates to drive supersonic turbulence in molecular clouds. Here, we present the results from multi-dimensional jet simulations where we investigate in detail the energy and momentum deposition from jets into their surrounding environment and quantify the character of the excited turbulence with velocity probability density functions. Our study include jet--clump interaction, transient jets, and magnetised jets. We find that collimated supersonic jets do not excite supersonic motions far from the vicinity of the jet. Supersonic fluctuations are damped quickly and do not spread into the parent cloud. Instead subsonic, non-compressional modes occupy most of the excited volume. This is a generic feature which can not be fully circumvented by overdense jets or magnetic fields. Nevertheless, jets are able to leave strong imprints in their cloud structure and can disrupt dense clumps. Our results question the ability of collimated jets to sustain supersonic turbulence in molecular clouds.Comment: 33 pages, 18 figures, accepted by ApJ, version with high resolution figures at: http://www.ita.uni-heidelberg.de/~banerjee/publications/jet_paper.pd

    Seasonal patterns of oral antihistamine and intranasal corticosteroid purchases from Australian community pharmacies : a retrospective observational study

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    Acknowledgments The abstract of this paper was presented at the Respiratory Effectiveness Group 2016 Annual Summit as a poster presentation with interim findings. The poster’s abstract was published in “Poster Abstracts” in The Journal of Thoracic Disease (Vol. 8, Supplement 5, 5 July 2016). http://jtd.amegroups.com/article/view/8504.Peer reviewedPublisher PD

    Molecular characterization, tissue expression and sequence variability of the barramundi (Lates calcarifer) myostatin gene

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    Background: Myostatin (MSTN) is a member of the transforming growth factor-β superfamily that negatively regulates growth of skeletal muscle tissue. The gene encoding for the MSTN peptide is a consolidate candidate for the enhancement of productivity in terrestrial livestock. This gene potentially represents an important target for growth improvement of cultured finfish.\ud \ud Results: Here we report molecular characterization, tissue expression and sequence variability of the barramundi (Lates calcarifer) MSTN-1 gene. The barramundi MSTN-1 was encoded by three exons 379, 371 and 381 bp in length and translated into a 376-amino acid peptide. Intron 1 and 2 were 412 and 819 bp in length and presented typical GT...AG splicing sites. The upstream region contained cis-regulatory elements such as TATA-box and E-boxes. A first assessment of sequence variability suggested that higher mutation rates are found in the 5' flanking region with several SNP's present in this species. A putative micro RNA target site has also been observed in the 3'UTR (untranslated region) and is highly conserved across teleost fish. The deduced amino acid sequence was conserved across vertebrates and exhibited characteristic conserved putative functional residues including a cleavage motif of proteolysis (RXXR), nine cysteines and two glycosilation sites. A qualitative analysis of the barramundi MSTN-1 expression pattern revealed that, in adult fish, transcripts are differentially expressed in various tissues other than skeletal muscles including gill, heart, kidney, intestine, liver, spleen, eye, gonad and brain.\ud \ud Conclusion: Our findings provide valuable insights such as sequence variation and genomic information which will aid the further investigation of the barramundi MSTN-1 gene in association with growth. The finding for the first time in finfish MSTN of a miRNA target site in the 3'UTR provides an opportunity for the identification of regulatory mutations on the expression of this gene
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