966 research outputs found

    Nitrogen determination in micas of metamorphic rocks

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    6 pages, 1 table, 1 figure.-- Proceedings of the Seventeenth International Conference on Ion Beam Analysis.-- El pdf del artículo es la versión post-print.-- et al.Micas are minerals that provide large amounts of information regarding geological processes, because of the sensitivity of their chemical composition to temperature, pressure and deformation of rocks in which they form. Rocks under analysis are formed of different minerals with variable grain size. Mica grain size may vary between 5 and 10 μm and approximately correspond to the chemical formula (Si3.2Al0.8)O10(Al1.9Fe0.05Mg0.1)(OH)2(K0.75Na0.05), being distinguishable from other minerals because of their composition and their morphology in secondary electron images and specially backscattered electron (BSE) images. NH4, when present, would partially substitute K in the previous formula. In some cases NH4-rich micas (tobelites) have been described coexisting with the corresponding K-rich micas, but the actual NH4 content of normal K-rich micas is still unknown. Low N content makes necessary to use nuclear reactions such as 14N(d, pγ)15N at 1.4 MeV and its cascade of intense γ-rays. For the quantification and localization of nitrogen on the surface of the samples, PIGE analysis was carried out in the vacuum microprobe line of the CNA, together with simultaneous micro-RBS and micro-PIXE analyses, giving a more comprehensive picture of sample structure and composition.Peer reviewe

    Expression and protein localisation of IGF2 in the marsupial placenta

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    <p>Abstract</p> <p>Background</p> <p>In eutherian mammals, genomic imprinting is critical for normal placentation and embryo survival. <it>Insulin-like growth factor 2 </it>(<it>IGF2</it>) is imprinted in the placenta of both eutherians and marsupials, but its function, or that of any imprinted gene, has not been investigated in any marsupial. This study examines the role of <it>IGF2 </it>in the yolk sac placenta of the tammar wallaby, <it>Macropus eugenii</it>.</p> <p>Results</p> <p><it>IGF2 </it>mRNA and protein were produced in the marsupial placenta. Both IGF2 receptors were present in the placenta, and presumably mediate IGF2 mitogenic actions. <it>IGF2 </it>mRNA levels were highest in the vascular region of the yolk sac placenta. IGF2 increased <it>vascular endothelial growth factor </it>expression in placental explant cultures, suggesting that IGF2 promotes vascularisation of the yolk sac.</p> <p>Conclusion</p> <p>This is the first demonstration of a physiological role for any imprinted gene in marsupial placentation. The conserved imprinting of <it>IGF2</it> in this marsupial and in all eutherian species so far investigated, but not in monotremes, suggests that imprinting of this gene may have originated in the placenta of the therian ancestor.</p

    A detailed study of the diastereoselective catalytic hydrogenation of 6-hydroxytetrahydroisoquinoline-(3R)-carboxylic ester intermediates

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    A key step towards a highly-selective antagonist of ionotropic glutamate receptors entails the diastereoselective arene hydrogenation of an enantiopure tetrahydroisoquinoline. An extensive screen using parallel reactors was conducted and led to the discovery of several Pd/C catalysts giving high yield and improved diastereoselectivity from 75 : 25 to 95 : 5. A detailed kinetic study of the best system was performed and supports the reduction occuring in two-steps.

    Evolution of the CDKN1C-KCNQ1 imprinted domain

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    <p>Abstract</p> <p>Background</p> <p>Genomic imprinting occurs in both marsupial and eutherian mammals. The <it>CDKN1C </it>and <it>IGF2 </it>genes are both imprinted and syntenic in the mouse and human, but in marsupials only <it>IGF2 </it>is imprinted. This study examines the evolution of features that, in eutherians, regulate <it>CDKN1C </it>imprinting.</p> <p>Results</p> <p>Despite the absence of imprinting, CDKN1C protein was present in the tammar wallaby placenta. Genomic analysis of the tammar region confirmed that <it>CDKN1C </it>is syntenic with <it>IGF2</it>. However, there are fewer LTR and DNA elements in the region and in intron 9 of <it>KCNQ1</it>. In addition there are fewer LINEs in the tammar compared with human and mouse. While the CpG island in intron 10 of <it>KCNQ1 </it>and promoter elements could not be detected, the antisense transcript <it>KCNQ1OT1 </it>that regulates <it>CDKN1C </it>imprinting in human and mouse is still expressed.</p> <p>Conclusion</p> <p>CDKN1C has a conserved function, likely antagonistic to IGF2, in the mammalian placenta that preceded its acquisition of imprinting. CDKN1C resides in synteny with IGF2, demonstrating that imprinting of the two genes did not occur concurrently to balance maternal and paternal influences on the growth of the placenta. The expression of <it>KCNQ1OT1 </it>in the absence of CDKN1C imprinting suggests that antisense transcription at this locus preceded imprinting of this domain. These findings demonstrate the stepwise accumulation of control mechanisms within imprinted domains and show that <it>CDKN1C </it>imprinting cannot be due to its synteny with <it>IGF2 </it>or with its placental expression in mammals.</p

    Expressions of psychological distress in Sierra Leone: Implications for community-based prevention and response

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    Alastair Ager - ORCID 0000-0002-9474-3563 https://orcid.org/0000-0002-9474-3563Replaced AM with VoR 2020-08-07Background Over recent decades there has been considerable mental health research in Sierra Leone but little on local conceptualisations of mental health conditions. Understanding these is crucial both for identifying the experienced needs of the population and utilising relevant community-based resources to address them. This study took a grounded approach to identify the ways in which adults in Sierra Leone express psychological distress.Methods Rapid ethnographic methods deployed included 75 case study interviews with community members, 12 key informant pile sorts and 55 key informant interviews. Thematic analysis of data was supported by frequency analysis and multi-dimensional scaling.Results Thirty signs of distress were identified. The only consistent ‘syndrome’ identified with respect to these was a general concept of crase, which referred to psychosis-related presentation but also a wide range of other signs of distress. We did not find consensus on locally defined concepts for mild-moderate forms of mental disorder: people use multiple overlapping signs and terms indicating psychological distress.Conclusions Analysis supports calls to view mental health problems as a ‘continuum of distress’ rather than as discrete categories. This framing is coherent with opportunities for prevention and response in Sierra Leone which do not focus primarily on formal health care service providers but rather involve a range of community-based actors. It also enables attention to be paid to the identification of milder signs of distress with a view to early response and prevention of more severe mental health problems.This research was funded by NIHR Global Health Research Programme 16/136/100, Queen Margaret University.https://doi.org/10.1017/gmh.2020.127pubpu

    A systematic review of community participation measures for people with intellectual disabilities

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    Background: Community participation is considered a fundamental aspect of quality of life and one of the essential goals of services for people with intellectual disabilities (ID), yet there is no agreed way of measuring community participation. Method: Two systematic searches were performed across eight electronic databases to identify measures of community participation and identify validation studies for each measure. Measures were included if they were developed for adults with ID, measured extent of participation and had published information regarding content and psychometric properties. Each measure was evaluated on the basis of psychometric properties and in relation to coverage of nine domains of community participation from the International Classification of Functioning, Disability and Health (ICF). Results: Eleven measures were selected with the quality rating scores varying substantially ranging from 2-11 of a possible 16. Conclusions: The majority of measures were not sufficiently psychometrically tested. Findings suggest a need for the development of a psychometrically robust instrument
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