92 research outputs found

    Interaction between electrostatic collisionless shocks generates strong magnetic fields

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    The head-on collision between electrostatic shocks is studied via multi-dimensional particle-in-cell simulations. A strong magnetic field develops after the interaction, which causes the shock velocities to drop significantly. This transverse magnetic field is generated by the Weibel instability, which is driven by pressure anisotropies due to longitudinal electron heating while the shocks approach each other. The possibility to explore the physics underpinning the shock collision in the laboratory with current laser facilities is discussed.info:eu-repo/semantics/publishedVersio

    The Debye-Waller Factor in solid 3He and 4He

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    The Debye-Waller factor and the mean-squared displacement from lattice sites for solid 3He and 4He were calculated with Path Integral Monte Carlo at temperatures between 5 K and 35 K, and densities between 38 nm^(-3) and 67 nm^(-3). It was found that the mean-squared displacement exhibits finite-size scaling consistent with a crossover between the quantum and classical limits of N^(-2/3) and N^(-1/3), respectively. The temperature dependence appears to be T^3, different than expected from harmonic theory. An anisotropic k^4 term was also observed in the Debye-Waller factor, indicating the presence of non-Gaussian corrections to the density distribution around lattice sites. Our results, extrapolated to the thermodynamic limit, agree well with recent values from scattering experiments.Comment: 5 figure

    Matrika Household Survey in India

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    Data produced as part of a study to evaluate the impact of the Matrika social franchising model – a multi-faceted intervention that established a network of private providers and strengthened the skills of both public and private sector clinicians – and determine whether it has improved the quality and coverage of health services along the continuum of care for maternal, newborn and reproductive health in Uttar Pradesh, India. The datasets cover two rounds of a household survey, performed in January 2015 and May 2016, of women who had recently given birth

    Improving statistical inference on pathogen densities estimated by quantitative molecular methods: malaria gametocytaemia as a case study

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    BACKGROUND: Quantitative molecular methods (QMMs) such as quantitative real-time polymerase chain reaction (q-PCR), reverse-transcriptase PCR (qRT-PCR) and quantitative nucleic acid sequence-based amplification (QT-NASBA) are increasingly used to estimate pathogen density in a variety of clinical and epidemiological contexts. These methods are often classified as semi-quantitative, yet estimates of reliability or sensitivity are seldom reported. Here, a statistical framework is developed for assessing the reliability (uncertainty) of pathogen densities estimated using QMMs and the associated diagnostic sensitivity. The method is illustrated with quantification of Plasmodium falciparum gametocytaemia by QT-NASBA. RESULTS: The reliability of pathogen (e.g. gametocyte) densities, and the accompanying diagnostic sensitivity, estimated by two contrasting statistical calibration techniques, are compared; a traditional method and a mixed model Bayesian approach. The latter accounts for statistical dependence of QMM assays run under identical laboratory protocols and permits structural modelling of experimental measurements, allowing precision to vary with pathogen density. Traditional calibration cannot account for inter-assay variability arising from imperfect QMMs and generates estimates of pathogen density that have poor reliability, are variable among assays and inaccurately reflect diagnostic sensitivity. The Bayesian mixed model approach assimilates information from replica QMM assays, improving reliability and inter-assay homogeneity, providing an accurate appraisal of quantitative and diagnostic performance. CONCLUSIONS: Bayesian mixed model statistical calibration supersedes traditional techniques in the context of QMM-derived estimates of pathogen density, offering the potential to improve substantially the depth and quality of clinical and epidemiological inference for a wide variety of pathogens

    The measurement of stress and phase fraction distributions in pre and post-transition Zircaloy oxides using nano-beam synchrotron X-ray diffraction

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    Zircaloy-4 oxide stress profiles and tetragonal:monoclinic oxide phase fraction distributions were studied using nano-beam transmission X-ray diffraction. Continuous stress relief and phase transformation during the first cycle of oxide growth was observed. The in-plane monoclinic stress was shown to relax strongly up to each transition, whereas in-plane tetragonal stress-relief (near the metal-oxide interface) was only observed post transition. The research demonstrates that plasticity in the metal and the development of a band of in-plane cracking both relax the monoclinic in-plane stress.The observations are consistent with a model of transition in which in-plane cracking becomes interlinked prior to transition. These cracks, combined with the development of cracks with a through-thickness component (driven primarily by plasticity in the metal) and/or a porous network of fine cracks (associated with phase transformation), form a percolation path through the oxide layer. The oxidising species can then percolate from the oxide surface to the metal/oxide interface, at which stage transition then ensues

    Bahinabai Chaudhari's songs : a performance tradition in Maharashtra, also known as “Grindmill Songs”, “Women's Work Songs”, “Ovi”, “Folk Songs”

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    Bahinabai Chaudhari, popularly remembered as Bahinai, was born in an agrarian village in the Jalgaon district of Maharashtra. She had three sisters and three brothers and was married off at the age of 13 to a Vatandar (landowning farmer) - Nathuji Chaudhari. Nathuji was 30 when he married Bahinai; Bahinai was 30 when she was widowed. Bahinai could not read or write. She spent most of her life toiling in farms and kitchens; as a widow, she did the same with the additional burden of clearing her husband’s financial debt. In this context of everyday labor, Bahinai sang a genre of song called ovi - short, rhyming, rhythmic couplets. She sang in the Khandeshi-Varhadi dialect of Marathi (also called Ahirani). Her songs were preserved and published posthumously by her son, Sopandev, and have since been a topic of academic writing and popular representation in films and school textbooks. Of the many themes that these songs address, Bahinai's devotion and love (bhakti) for Vitthal (an avatar of Krishna worshipped by Varkaris) is persistent. I, therefore, think that exploring her performance tradition in the disciplinary context of religion could raise important questions - what were the different ways of worshipping Vitthal in Bahinai's immediate context? Why did she sing ovis in the midst of everyday labor like grinding grain and threshing wheat? Are these activities 'religious' or 'folk' or both or neither? Do larger categories like Hinduism elucidate Bahinai's songs at all? And what are the gendered aspects of this genre - in terms of its history and contemporary practice? The following questionnaire is a rudimentary attempt to address these questions.Non UBCUnreviewedGraduat
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