1,587 research outputs found

    Magnetowave Induced Plasma Wakefield Acceleration for Ultra High Energy Cosmic Rays

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    Magnetowave induced plasma wakefield acceleration (MPWA) in a relativistic astrophysical outflow has been proposed as a viable mechanism for the acceleration of cosmic particles to ultra high energies. Here we present simulation results that clearly demonstrate the viability of this mechanism for the first time. We invoke the high frequency and high speed whistler mode for the driving pulse. The plasma wakefield so induced validates precisely the theoretical prediction. We show that under appropriate conditions, the plasma wakefield maintains very high coherence and can sustain high-gradient acceleration over a macroscopic distance. Invoking gamma ray burst (GRB) as the source, we show that MPWA production of ultra high energy cosmic rays (UHECR) beyond ZeV 10^21 eV is possible.Comment: 4 pages, 4 figure

    Upper Limit on the Cosmological Gamma-ray Background

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    We show that the current extragalactic gamma-ray background (EGB) measurement below 100 GeV sets an upper limit on EGB itself at very high energy (VHE) above 100 GeV. The limit is conservative for the electromagnetic cascade emission from VHE EGB interacting with the cosmic microwave-to-optical background radiation not to exceed the current EGB measurement. The cascade component fits the measured VHE EGB spectrum rather well. However, once we add the contribution from known source classes, the Fermi VHE EGB observation exceeds or even violates the limit, which is approximated as E^2dN/dE < 4.5x10^-5 (E/100 GeV)^-0.7 MeV/cm^2/s/sr. The upper limit above 100 GeV is useful in the future to probe the EGB origin and the new physics like axion-like particles and Lorentz-invariance violation.Comment: 8 pages, 8 figures, accepted for publication in PRD, Interested readers may wish to consult the recent paper by Murase, Beacom and Takami (arXiv:1205.5755

    A Comparative Proteomic Analysis Reveals a New Bi-Lobe Protein Required for Bi-Lobe Duplication and Cell Division in Trypanosoma brucei

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    A Golgi-associated bi-lobed structure was previously found to be important for Golgi duplication and cell division in Trypanosoma brucei. To further understand its functions, comparative proteomics was performed on extracted flagellar complexes (including the flagellum and flagellum-associated structures such as the basal bodies and the bi-lobe) and purified flagella to identify new bi-lobe proteins. A leucine-rich repeats containing protein, TbLRRP1, was characterized as a new bi-lobe component. The anterior part of the TbLRRP1-labeled bi-lobe is adjacent to the single Golgi apparatus, and the posterior side is tightly associated with the flagellar pocket collar marked by TbBILBO1. Inducible depletion of TbLRRP1 by RNA interference inhibited duplication of the bi-lobe as well as the adjacent Golgi apparatus and flagellar pocket collar. Formation of a new flagellum attachment zone and subsequent cell division were also inhibited, suggesting a central role of bi-lobe in Golgi, flagellar pocket collar and flagellum attachment zone biogenesis

    Quality of life and visual function in Nigeria: findings from the National Survey of Blindness and Visual Impairment

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    Aims To assess associations of visual function (VF) and quality of life (QOL) by visual acuity (VA), causes of blindness and types of cataract procedures in Nigeria. Methods Multi-stage stratified cluster random sampling was used to identify a nationally representative sample of persons aged >= 40 years. VF/QOL questionnaires were administered to participants with VA = 6/12. Results VF/QOL questionnaires were administered to 2076 participants. Spearman's rank correlation showed a strong correlation between decreasing VA and VF/QOL scores (p< 0.0001) with greatest impact on social (p< 0.0001) and mobility-related activities (p< 0.0001). People who were blind due to glaucoma had lower VF and QOL scores than those who were blind due to cataract. Mean VF and QOL scores were lower after couching compared with conventional cataract surgery (mean VF score=51.0 vs 63.0 and mean QOL score=71.3 vs 79.3). Finally, VF and QOL scores were lower among populations with specific characteristics. Conclusions Populations with the following characteristics should be targeted to improve VF and QOL: people who are blind, older people, women, manual labourers, people living in rural areas, those living in the northern geopolitical zones, those practising Islamic and Traditionalism faith, those not currently married and those who have undergone couching

    Association of Body Mass Index of HIV-1-Infected Pregnant Women and Infant Weight, Body Mass Index, Length, and Head Circumference: The NISDI Perinatal Study.

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    This study assessed the relationship between the body mass index (BMI) of HIV-1-infected women and their infants' perinatal outcomes. The study population consisted of women enrolled in the NICHD International Site Development Initiative (NISDI) Perinatal Study with data allowing calculation of the BMI adjusted for length of gestation (adjBMI), who delivered singleton infants. Outcome variables included infant growth parameters at birth (weight, BMI, length and head circumference) and gestational age. Of 697 women from Argentina, the Bahamas, Brazil and Mexico who were included in the analysis, the adjBMI was classified as underweight for 109 (15.6%), normal for 418 (60.0%), overweight for 88 (12.6%) and obese for 82 (11.8%). Median infant birth weight, BMI, birth length and head circumference differed significantly according to maternal adjBMI (P</=0.0002). Underweight mothers gave birth to infants with lower weight, lower BMI, shorter length and smaller head circumference, while infants born to normal, overweight and obese mothers were of similar size

    Effective Field Theory and Finite Density Systems

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    This review gives an overview of effective field theory (EFT) as applied at finite density, with a focus on nuclear many-body systems. Uniform systems with short-range interactions illustrate the ingredients and virtues of many-body EFT and then the varied frontiers of EFT for finite nuclei and nuclear matter are surveyed.Comment: 27 pages, 5 figure

    The training and organization of Paediatric Neurology in Europe : Special report of the European Paediatric Neurology Society & Committee of National Advisors

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    Background: Paediatric Neurology (PN) is a discipline focused on diagnosis, comprehensive management and research into diseases of the central and peripheral nervous system from fetal life to transition into adulthood. The European Paediatric Neurology Society first designed and published the European PN training programme in the European Paediatric Neurology Syllabus in 2002. This was important in gaining recognition for the sub-specialty from the European Academy of Paediatrics and the European Academy of Neurology and in 2003 PN was recognized as a sub-specialty of paediatrics and neurology by the Board of the European Union of Medical Specialties. In 2004, the EPNS founded the Committee of National Advisors (CNA) that comprised representatives from national Paediatric Neurology societies, in order to further enhance Europe wide standards in training and practice., The EPNS Training Advisory Board (TAB) offers nation specific advice/support to PN societies on developing training and care systems. In 2019, the 2nd revision of the Paediatric Neurology Syllabus was approved by the EPNS Board and CNA. We aim to give an overview of the training of Paediatric Neurology (PN) specialists (i.e. Paediatric Neurologists), the relevant professional bodies and the current practice of Paediatric Neurology in Europe, as defined geographically by the World Health Organization. Methods: A structured online data collection form was completed by CNA representatives from European countries. The data included training routes and structure of training, epidemiological data, nature of professional societies, organization of Paediatric Neurology care, research, academic life and recognition of the specialty. Results: Data was collected from 43 European countries of which 38 have a national PN Society. In 10 (6 European Union (EU) and 4 non-EU countries) PN is recognized as a core specialty. In 26 countries PN is recognized as a sub-specialty of Paediatrics, Neurology or both (15 EU-11 non-EU). PN is not recognized as a core or sub-specialty in 7 countries (4 EU and 3 non-EU). In 35 countries paediatric neurologists begin their training from Paediatrics, but in 19 countries PN training from Neurology is also possible or the preferred route. Training in PN differs, but in over 50% of countries the three main training modules named in the 2019 2nd revision of the European PN Syllabus (PN, Paediatrics and adult Neurology) are included. Many countries have already adapted their curriculum to the suggestions in the European PN syllabus. Conclusions: There is diversity among European countries in terms of professional organization and PN training. The European PN syllabus has had impact on the development of PN training throughout Europe, independent of duration of training or route from paediatrics or neurology. The syllabus provides a basis for the future development of PN training, the recognition of PN as a (sub) specialty in individual countries and for improving the care of children with neurological disorders in Europe. (c) 2020 The Authors. Published by Elsevier Ltd on behalf of European Paediatric Neurology Society.Peer reviewe

    Superconductivity in iron telluride thin films under tensile stress

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    By realizing in thin films a tensile stress state, superconductivity of 13 K was introduced into FeTe, an non-superconducting parent compound of the iron pnictides and chalcogenides, with transition temperature higher than that of its superconducting isostructural counterpart FeSe. For these tensile stressed films, the superconductivity is accompanied by the softening of the first-order magnetic and structural phase transition; and also, the in-plane extension and out-of-plane contraction are universal in all FeTe films independent of sign of lattice mismatch, either positive or negative. Moreover, the correlations were found exist between the transition temperatures and the tetrahedra bond angles in these thin films.Comment: 4 pages, 4 figures, accepted by Physical Review Letter
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