784 research outputs found

    Deficiency in infinite-dimensional manifolds

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    AbstractThis paper is largely devoted to proving the following result: Let E be a Fréchet space homeomorphic to its own countable infinite product, M be a paracompact manifold modeled on E, and let K ⊂ M be closed. Then there exists a homeomorphism of M onto M × E taking K into M × {0} iff for each non-null, homotopically trivial open set U in M, U⧹K is non-null and homotopically trivial. A similar result for E = 2 (separable Hilbert space) is known

    Isospectrality in Chaotic Billiards

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    We consider a modification of isospectral cavities whereby the classical dynamics changes from pseudointegrable to chaotic. We construct an example where we can prove that isospectrality is retained. We then demonstrate this explicitly in microwave resonators.Comment: 5 pages, 7 figure

    Preschool hearing, speech, language, and vision screening

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    Child health surveillance is part of a broad set of activities, the objective of which is to reduce childhood disability by identifying and managing a multiplicity of conditions at an early stage.1 This includes several screening programmes which are focused on the detection of specific disorders. The value of surveillance and monitoring of child health, growth, and development used to be regarded as self evident. The Hall reports emphasised the importance of applying rigorous criteria for screening programmes in community child health and helped to produce a more coordinated national programme.2–4 However, there is still considerable variation both within and between health authorities in the content, timing, and delivery of child health surveillance. This paper summarises the research evidence presented in a recent issue of the Effective Health Care bulletin, Vol 4, No 2; April, 1998 about hearing, speech and language, and vision screening and is based on recent systematic reviews commissioned by the National Health Service (NHS) Health Technology Assessment Programme. Details of the methods and the results are available in the full reports.5–

    Conservation of co-evolved interactions: understanding the Maculinea–Myrmica complex

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    1. The six papers in this Special Issue of Insect Conservation and Diversity are presented as a gedenkschrift honouring ground‐breaking contributions made by the late Graham Elmes towards understanding the biology of Myrmica ants and their social parasites. 2. A common theme is that each research paper contributes new knowledge applicable to the future survival of Maculinea (= Phengaris) species of butterflies, which have become flagships for insect conservation across Europe. All Maculinea species are highly specialised, with larvae that feed briefly on a specific foodplant before living underground for 11–23 months as social parasites of Myrmica colonies. 3. This introductory overview provides a brief history of the research that has led to the current collection, with emphasis on Graham Elmes' life and work. It is followed by three research papers that illustrate the diversity, socio‐biology and ecology of Myrmica ants. A fourth describes an extreme adaptation that increases the efficiency with which some populations of Maculinea larvae exploit the resources within Myrmica nests. A fifth, more theoretical, paper models the constraints that typically lead to host specificity among social parasites and explores why host switches are rare and quick

    Maternal race and intergenerational preterm birth recurrence

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    Background Preterm birth is a complex disorder with a heritable genetic component. Studies of primarily White women born preterm show that they have an increased risk of subsequently delivering preterm. This risk of intergenerational preterm birth is poorly defined among Black women. Objective Our objective was to evaluate and compare intergenerational preterm birth risk among non-Hispanic Black and non-Hispanic White mothers. Study Design This was a population-based retrospective cohort study, using the Virginia Intergenerational Linked Birth File. All non-Hispanic Black and non-Hispanic White mothers born in Virginia 1960 through 1996 who delivered their first live-born, nonanomalous, singleton infant ≥20 weeks from 2005 through 2009 were included. We assessed the overall gestational age distribution between non-Hispanic Black and White mothers born term and preterm (<37 weeks) and their infants born term and preterm (<37 weeks) using Cox regression and Kaplan-Meier survivor functions. Mothers were grouped by maternal gestational age at delivery (term, ≥37 completed weeks; late preterm birth, 34-36 weeks; and early preterm birth, <34 weeks). The primary outcomes were: (1) preterm birth among all eligible births; and (2) suspected spontaneous preterm birth among births to women with medical complications (eg, diabetes, hypertension, preeclampsia and thus higher risk for a medically indicated preterm birth). Multivariable logistic regression was used to estimate odds of preterm birth and spontaneous preterm birth by maternal race and maternal gestational age after adjusting for confounders including maternal education, maternal age, smoking, drug/alcohol use, and infant gender. Results Of 173,822 deliveries captured in the intergenerational birth cohort, 71,676 (41.2%) women met inclusion criteria for this study. Of the entire cohort, 30.0% (n = 21,467) were non-Hispanic Black and 70.0% were non-Hispanic White mothers. Compared to non-Hispanic White mothers, non-Hispanic Black mothers were more likely to have been born late preterm (6.8% vs 3.7%) or early preterm (2.8 vs 1.0%), P <.001. Non-Hispanic White mothers who were born (early or late) preterm were not at an increased risk of early or late preterm delivery compared to non-Hispanic White mothers born term. The risk of early preterm birth was most pronounced for Black mothers who were born early preterm (adjusted odds ratio, 3.26; 95% confidence interval, 1.77–6.02) compared to non-Hispanic White mothers. Conclusion We found an intergenerational effect of preterm birth among non-Hispanic Black mothers but not non-Hispanic White mothers. Black mothers born <34 weeks carry the highest risk of delivering their first child very preterm. Future studies should elucidate the underlying pathways leading to this racial disparity

    Bose-Einstein Correlations of Charged Kaons in Central Pb+Pb Collisions at Ebeam=158AGeVE_{beam} = 158 AGeV

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    Bose-Einstein correlations of charged kaons were measured near mid-rapidity in central Pb+Pb collisions at 158 A\cdotGeV by the NA49 experiment at the CERN SPS. Source radii were extracted using the Yano-Koonin-Podgoretsky and Bertsch-Pratt parameterizations. The results are compared to published pion data. The measured mm_\perp dependence for kaons and pions is consistent with collective transverse expansion of the source and a freeze-out time of about 9.5 fmfm.Comment: 14 pages with 7 figures, submitted to Phys. Lett.

    A Helicity-Based Method to Infer the CME Magnetic Field Magnitude in Sun and Geospace: Generalization and Extension to Sun-Like and M-Dwarf Stars and Implications for Exoplanet Habitability

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    Patsourakos et al. (Astrophys. J. 817, 14, 2016) and Patsourakos and Georgoulis (Astron. Astrophys. 595, A121, 2016) introduced a method to infer the axial magnetic field in flux-rope coronal mass ejections (CMEs) in the solar corona and farther away in the interplanetary medium. The method, based on the conservation principle of magnetic helicity, uses the relative magnetic helicity of the solar source region as input estimates, along with the radius and length of the corresponding CME flux rope. The method was initially applied to cylindrical force-free flux ropes, with encouraging results. We hereby extend our framework along two distinct lines. First, we generalize our formalism to several possible flux-rope configurations (linear and nonlinear force-free, non-force-free, spheromak, and torus) to investigate the dependence of the resulting CME axial magnetic field on input parameters and the employed flux-rope configuration. Second, we generalize our framework to both Sun-like and active M-dwarf stars hosting superflares. In a qualitative sense, we find that Earth may not experience severe atmosphere-eroding magnetospheric compression even for eruptive solar superflares with energies ~ 10^4 times higher than those of the largest Geostationary Operational Environmental Satellite (GOES) X-class flares currently observed. In addition, the two recently discovered exoplanets with the highest Earth-similarity index, Kepler 438b and Proxima b, seem to lie in the prohibitive zone of atmospheric erosion due to interplanetary CMEs (ICMEs), except when they possess planetary magnetic fields that are much higher than that of Earth.Comment: http://adsabs.harvard.edu/abs/2017SoPh..292...89

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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