2,175 research outputs found

    Metabolomics application in maternal-fetal medicine

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    Metabolomics in maternal-fetal medicine is still an "embryonic" science. However, there is already an increasing interest in metabolome of normal and complicated pregnancies, and neonatal outcomes. Tissues used for metabolomics interrogations of pregnant women, fetuses and newborns are amniotic fluid, blood, plasma, cord blood, placenta, urine, and vaginal secretions. All published papers highlight the strong correlation between biomarkers found in these tissues and fetal malformations, preterm delivery, premature rupture of membranes, gestational diabetes mellitus, preeclampsia, neonatal asphyxia, and hypoxic-ischemic encephalopathy. The aim of this review is to summarize and comment on original data available in relevant published works in order to emphasize the clinical potential of metabolomics in obstetrics in the immediate future

    Finite element elastic-plastic-creep and cyclic life analysis of a cowl lip

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    Results are presented of elastic, elastic-plastic, and elastic-plastic-creep analyses of a test-rig component of an actively cooled cowl lip. A cowl lip is part of the leading edge of an engine inlet of proposed hypersonic aircraft and is subject to severe thermal loadings and gradients during flight. Values of stresses calculated by elastic analysis are well above the yield strength of the cowl lip material. Such values are highly unrealistic, and thus elastic stress analyses are inappropriate. The inelastic (elastic-plastic and elastic-plastic-creep) analyses produce more reasonable and acceptable stress and strain distributions in the component. Finally, using the results from these analyses, predictions are made for the cyclic crack initiation life of a cowl lip. A comparison of predicted cyclic lives shows the cyclic life prediction from the elastic-plastic-creep analysis to be the lowest and, hence, most realistic

    Elastic/plastic analyses of advanced composites investigating the use of the compliant layer concept in reducing residual stresses resulting from processing

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    High residual stresses within intermetallic and metal matrix composite systems can develop upon cooling from the processing temperature to room temperature due to the coefficient of thermal expansion (CTE) mismatch between the fiber and matrix. As a result, within certain composite systems, radial, circumferential, and/or longitudinal cracks have been observed to form at the fiber-matrix interface. The compliant layer concept (insertion of a compensating interface material between the fiber and matrix) was proposed to reduce or eliminate the residual stress buildup during cooling and thus minimize cracking. The viability of the proposed compliant layer concept is investigated both elastically and elastoplastically. A detailed parametric study was conducted using a unit cell model consisting of three concentric cylinders to determine the required character (i.e., thickness and material properties) of the compliant layer as well as its applicability. The unknown compliant layer mechanical properties were expressed as ratios of the corresponding temperature dependent Ti-24Al-11Nb (a/o) matrix properties. The fiber properties taken were those corresponding to SCS-6 (SiC). Results indicate that the compliant layer can be used to reduce, if not eliminate, radial and circumferential residual stresses within the fiber and matrix and therefore also reduce or eliminate the radial cracking. However, with this decrease in in-plane stresses, one obtains an increase in longitudinal stress, thus potentially initiating longitudinal cracking. Guidelines are given for the selection of a specific compliant material, given a perfectly bonded system

    The STROBE extensions: protocol for a qualitative assessment of content and a survey of endorsement

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    Introduction The STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) Statement was developed in response to inadequate reporting of observational studies. In recent years, several extensions to STROBE have been created to provide more nuanced field-specific guidance for authors. The content and the prevalence of extension endorsement have not yet been assessed. Accordingly, there are two aims: (1) to classify changes made in the extensions to identify strengths and weaknesses of the original STROBE checklist and (2) to determine the prevalence and typology of endorsement by journals in fields related to extensions. Methods and analysis Two independent researchers will assess additions in each extension. Additions will be coded as â field specific' (FS) or â not field specific' (NFS). FS is defined as particularly relevant information for a single field and guidance provided generally cannot be extrapolated beyond that field. NFS is defined as information that reflects epidemiological or methodological tenets and can be generalised to most, if not all, types of observational research studies. Intraclass correlation will be calculated to measure reviewers' concordance. On disagreement, consensus will be sought. Individual additions will be grouped by STROBE checklist items to identify the frequency and distribution of changes. Journals in fields related to extensions will be identified through National Library of Medicine PubMed Broad Subject Terms, screened for eligibility and further distilled via Ovid MEDLINE® search strategies for observational studies. Text describing endorsement will be extracted from each journal's website. A classification scheme will be created for endorsement types and the prevalence of endorsement will be estimated. Analyses will use NVivo V.11 and SAS University Edition. Ethics and dissemination This study does not require ethical approval as it does not involve human participants. This study has been preregistered on Open Science Framework.Peer ReviewedPostprint (author's final draft

    Increasing solar panel efficiency in a sustainable manner

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    Solar panel output is determined by a number of factors: obviously there is the type of panel that determines the conversion efficiency, but also the amount of light falling into the panel is of importance, among other conditions of operation. The output of a panel would e.g. drop when the amount of light falling onto it is reduced, or even when only a part of the panel is covered. Another reason for reduced output lies in the fact that the conversion efficiency drops by about 0.38 % per °C increase in panel temperature. Considering that a panel would be able to produce most of its output on a sunny day, the reduction in efficiency due to heating up is of significant importance. To achieve an optimised output, it is therefore important for the panel to remain clean, but also keep it as cool as possible. Therefore, this paper looks at a method of running water on top of a solar panel in order to clean it and cool it down. To reduce the energy consumption of moving the water from the bottom of the panel back to the top, it exploits the kinetic energy of the water that runs down the panel to pump the water back to the top. Measurements indicate that this approach leads to an average increase in output of about 12 %

    Educational Conditions of Schoolchildren of 7-8 Grades Competence Formation in Innovative Schools

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    The article studies methodological system of extracurricular classes, aimed at the development of senior schoolchildren’s key competences, determines educational conditions of schoolchildren’s key competences development in the course of extracurricular activities, develops the principles and ways to control schoolchildren’s independent activity; programs of training workshops for teachers and senior schoolchildren, considers some aspects of senior schoolchildren’s key competences development in the course of extracurricular classes.Educational conditions, which are necessary for competence approach to senior schoolchildren’s extracurricular activities are the following: schoolchildren’s learning and educability levels, motives, interests, professional plans determination; review of requirements for knowledge and skills of schoolchildren, learning from minimal (basic) to the advanced level of academic subject learning.We consider further didactic and methodological works of profound subject provision of the system of extracurricular classes in the framework of competence approach, including initial and major school levels as prospect trends of this problem stud

    Intrinsic parton motion soft mechanisms and the longitudinal spin asymmetry A_LL in high energy pp -> pi X

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    The longitudinal double spin asymmetry A_LL in the reaction pp --> pi X has been measured at RHIC with extremely interesting consequences. If the gluon polarization in a proton were as big as needed to resolve the famous "spin crisis" then A_LL would be large and positive. Latest RHIC results indicate that A_LL is small and disfavour large positive values of the gluon polarization. We examine whether the soft mechanisms (Collins, Sivers, Boer-Mulders), essential for generating transverse single spin asymmetries, have any significant influence on A_LL, and whether they could alter the conclusion that the gluon polarization is necessarily small. It turns out that the contribution from these effects is essentially negligible.Comment: RevTeX, 9 pages, 3 eps figures. Revised and shortened version; title slightly modified; figs. 3,4 removed; a new figure for the unpol. cross section added; no changes in results and conclusions; matches the published versio
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