1,301 research outputs found

    Laboratory investigation of the impact of air pollution on partial discharge inception voltage of insulators in a specific region

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    Studying the discharge characteristics of transmission line insulators in the presence of pollution, particularly when the contaminated layer is wet by rain, fog or condensation, is necessary for selecting the proper insulation. Therefore, identifying the major air pollutants as well as the most effective ones on the discharge performance of outdoor insulators is mandatory. A systematic approach has been proposed to evaluate the impact of dominant air pollutants of an area on partial discharge (P.D) inception voltage of specimen insulators. Based on the suggested method, determining the pollution constituents, defining the dominant pollutant of the area, finding the most commonly used insulators for medium and above distribution voltages within the geographical boundaries of the Central Province of Iran, as well as examining the effect of dominant air pollutant of the region on partial discharge inception voltage of designated insulators by laboratory measurements, are the necessary steps toward a comprehensive study of the subject

    Mapping neurotransmitter systems to the structural and functional organization of the human neocortex

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    Neurotransmitter receptors support the propagation of signals in the human brain. How receptor systems are situated within macro-scale neuroanatomy and how they shape emergent function remain poorly understood, and there exists no comprehensive atlas of receptors. Here we collate positron emission tomography data from more than 1,200 healthy individuals to construct a whole-brain three-dimensional normative atlas of 19 receptors and transporters across nine different neurotransmitter systems. We found that receptor profiles align with structural connectivity and mediate function, including neurophysiological oscillatory dynamics and resting-state hemodynamic functional connectivity. Using the Neurosynth cognitive atlas, we uncovered a topographic gradient of overlapping receptor distributions that separates extrinsic and intrinsic psychological processes. Finally, we found both expected and novel associations between receptor distributions and cortical abnormality patterns across 13 disorders. We replicated all findings in an independently collected autoradiography dataset. This work demonstrates how chemoarchitecture shapes brain structure and function, providing a new direction for studying multi-scale brain organization

    Proton-deuteron radiative capture cross sections at intermediate energies

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    Differential cross sections of the reaction p(d,3He)γp(d,^3{\rm He})\gamma have been measured at deuteron laboratory energies of 110, 133 and 180 MeV. The data were obtained with a coincidence setup measuring both the outgoing 3^3He and the photon. The data are compared with modern calculations including all possible meson-exchange currents and two- and three- nucleon forces in the potential. The data clearly show a preference for one of the models, although the shape of the angular distribution cannot be reproduced by any of the presented models.Comment: 6 pages, 6 figures, accepted for publication in EPJ

    Fractionation of cellulose nanocrystals : enhancing liquid crystal ordering without promoting gelation

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    Colloids of electrically charged nanorods can spontaneously develop a fluid yet ordered liquid crystal phase, but this ordering competes with a tendency to form a gel of percolating rods. The threshold for ordering is reduced by increasing the rod aspect ratio, but the percolation threshold is also reduced with this change; hence, prediction of the outcome is nontrivial. Here, we show that by establishing the phase behavior of suspensions of cellulose nanocrystals (CNCs) fractionated according to length, an increased aspect ratio can strongly favor liquid crystallinity without necessarily influencing gelation. Gelation is instead triggered by increasing the counterion concentration until the CNCs lose colloidal stability, triggering linear aggregation, which promotes percolation regardless of the original rod aspect ratio. Our results shine new light on the competition between liquid crystal formation and gelation in nanoparticle suspensions and provide a path for enhanced control of CNC self-organization for applications in photonic crystal paper or advanced composites

    Magnetic hot spots in closely spaced thick gold nanorings

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    This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nano Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/page/policy/articlesonrequest/index.htmlLigh-matter interaction at optical frequencies is mostly mediated by the electric component of the electromagnetic field, with the magnetic component usually being considered negligible. Recently, it has been shown that properly engineered metallic nanostructures can provide a magnetic response at optical frequencies originated from real or virtual flows of electric current in the structure. In this work, we demonstrate a magnetic plasmonic mode which emerges in closely spaced thick gold nanorings. The plasmonic resonance obtains a magnetic dipole character by sufficiently increasing the height of the nanorings. Numerical simulations show that a virtual current loop appears at resonance for sufficiently thick nanorings, resulting in a strong concentration of the magnetic field in the gap region (magnetic hot spot). We find that there is an optimum thickness that provides the maximum magnetic intensity enhancement (over 200-fold enhancement) and give an explanation of this observation. This strong magnetic resonance, observed both experimentally and theoretically, can be used to build new metamaterials and resonant loop nanoantennas at optical frequencies.This work has been supported by Spanish Government and European Union (EU) funds under contracts CSD2008-00066 and TEC2011-28664-C02-02 and Universitat Politecnica de Valencia (program INNOVA 2011). The authors extend special thanks to Mr. J. Ross Aitken for his contribution to this work.Lorente Crespo, M.; Wang, L.; Ortuño Molinero, R.; García Meca, C.; Ekinci, Y.; Martínez Abietar, AJ. (2013). Magnetic hot spots in closely spaced thick gold nanorings. Nano Letters. 13(6):2654-2661. https://doi.org/10.1021/nl400798sS2654266113

    Gaining insight into how women conceptualize satisfaction: Western Australian women's perception of their maternity care experiences

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    BACKGROUND: The concept of maternal satisfaction is challenging, as women's and clinicians' expectations and experiences can differ. Our aim was to investigate women's experiences of maternity care in an urban tertiary obstetric setting, to gain insight into conceptualization of satisfaction across the childbirth continuum. METHODS: This mixed method study was conducted at a public maternity hospital in Western Australia. A questionnaire was sent to 733 women two weeks post birth, which included an invitation for an audio-recorded, telephone interview. Frequency distributions and univariate comparisons were employed for quantitative data. Thematic analysis of interview transcripts was undertaken to extract common themes. RESULTS: A total of 54 % (399 of 733) returned the questionnaire. Quantitative results indicated that women were less likely to feel: involved if they did not have a spontaneous vaginal birth (P?=?0.020); supported by a midwife if they had a caesarean (P?=?<0.001); or supported by an obstetrician if they had a spontaneous vaginal birth (P?=?<0.001). Qualitative findings emerged from 63 interviews which highlighted the influence that organization of care, resources and facilities had on women's satisfaction. These paradigms unfolded as three broad themes constructed by four sub-themes, each illustrating a dichotomy of experiences. The first theme 'how care was provided' encompassed: familiar faces versus a different one every time and the best place to be as opposed to so disappointed. The second theme 'attributes of staff' included: above and beyond versus caring without caring and in good hands as opposed to handled incorrectly. The third theme 'engaged in care' incorporated: explained everything versus did not know why and had a choice as opposed to did not listen to my needs. CONCLUSIONS: Quantitative analysis confirmed that the majority of women surveyed were satisfied. Mode of birth influenced women's perception of being involved with their birth. Being able to explore the diversity of women's experiences in relation to satisfaction with their maternity care in an urban, tertiary obstetric setting has offered greater insight into what women value: a sensitive, respectful, shared relationship with competent clinicians who recognise and strive to provide woman focused care across the childbirth continuum

    Comprehensive molecular portraits of human breast tumours

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    We analysed primary breast cancers by genomic DNA copy number arrays, DNA methylation, exome sequencing, messenger RNA arrays, microRNA sequencing and reverse-phase protein arrays. Our ability to integrate information across platforms provided key insights into previously defined gene expression subtypes and demonstrated the existence of four main breast cancer classes when combining data from five platforms, each of which shows significant molecular heterogeneity. Somatic mutations in only three genes (TP53, PIK3CA and GATA3) occurred at.10% incidence across all breast cancers; however, there were numerous subtype-associated and novel gene mutations including the enrichment of specific mutations in GATA3, PIK3CA and MAP3K1 with the luminal A subtype. We identified two novel protein-expression-defined subgroups, possibly produced by stromal/microenvironmental elements, and integrated analyses identified specific signalling pathways dominant in each molecular subtype including a HER2/phosphorylated HER2/EGFR/phosphorylated EGFR signature within the HER2-enriched expression subtype. Comparison of basal-like breast tumours with high-grade serous ovarian tumours showed many molecular commonalities, indicating a related aetiology and similar therapeutic opportunities. The biological finding of the four main breast cancer subtypes caused by different subsets of genetic and epigenetic abnormalities raises the hypothesis that much of the clinically observable plasticity and heterogeneity occurs within, and not across, these major biological subtypes of breast cancer. © 2012 Macmillan Publishers Limited. All rights reserved
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