19,025 research outputs found

    High-order, Dispersionless "Fast-Hybrid" Wave Equation Solver. Part I: O(1)\mathcal{O}(1) Sampling Cost via Incident-Field Windowing and Recentering

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    This paper proposes a frequency/time hybrid integral-equation method for the time dependent wave equation in two and three-dimensional spatial domains. Relying on Fourier Transformation in time, the method utilizes a fixed (time-independent) number of frequency-domain integral-equation solutions to evaluate, with superalgebraically-small errors, time domain solutions for arbitrarily long times. The approach relies on two main elements, namely, 1) A smooth time-windowing methodology that enables accurate band-limited representations for arbitrarily-long time signals, and 2) A novel Fourier transform approach which, in a time-parallel manner and without causing spurious periodicity effects, delivers numerically dispersionless spectrally-accurate solutions. A similar hybrid technique can be obtained on the basis of Laplace transforms instead of Fourier transforms, but we do not consider the Laplace-based method in the present contribution. The algorithm can handle dispersive media, it can tackle complex physical structures, it enables parallelization in time in a straightforward manner, and it allows for time leaping---that is, solution sampling at any given time TT at O(1)\mathcal{O}(1)-bounded sampling cost, for arbitrarily large values of TT, and without requirement of evaluation of the solution at intermediate times. The proposed frequency-time hybridization strategy, which generalizes to any linear partial differential equation in the time domain for which frequency-domain solutions can be obtained (including e.g. the time-domain Maxwell equations), and which is applicable in a wide range of scientific and engineering contexts, provides significant advantages over other available alternatives such as volumetric discretization, time-domain integral equations, and convolution-quadrature approaches.Comment: 33 pages, 8 figures, revised and extended manuscript (and now including direct comparisons to existing CQ and TDIE solver implementations) (Part I of II

    Dedication to Professor Jean M. Cary

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    Dedication to Professor Jean M. Cary

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    Ultra Bright LED Light Injection Calibration System for MINOS

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    We describe here a proposal for a light injection calibration system for the MINOS detectors based on ultra bright blue LEDs as the light source. We have shown that these LEDs are bright enough to span over two orders of magnitude in light intensity, commensurate with that expected in a single scintillator strip in the MINOS neutrino detectors.Comment: 9 pages, 13 figures, Submitted to NI

    Radio-frequency dressing of multiple Feshbach resonances

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    We demonstrate and theoretically analyze the dressing of several proximate Feshbach resonances in Rb-87 using radio-frequency (rf) radiation. We present accurate measurements and characterizations of the resonances, and the dramatic changes in scattering properties that can arise through the rf dressing. Our scattering theory analysis yields quantitative agreement with the experimental data. We also present a simple interpretation of our results in terms of rf-coupled bound states interacting with the collision threshold.Comment: 4+ pages, 3 figures, 1 table; revised introduction & references to reflect published versio

    Childhood IQ and risk of bipolar disorder in adulthood: prospective birth cohort study

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    Background: Intellectual ability may be an endophenotypic marker for bipolar disorder. Aims: Within a large birth cohort, we aimed to assess whether childhood IQ (including both verbal IQ (VIQ) and performance IQ (PIQ) subscales) was predictive of lifetime features of bipolar disorder assessed in young adulthood. Method: We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC), a large UK birth cohort, to test for an association between measures of childhood IQ at age 8 years and lifetime manic features assessed at age 22–23 years using the Hypomania Checklist-32 (HCL-32; n=1881 individuals). An ordinary least squares linear regression model was used, with normal childhood IQ (range 90–109) as the referent group. We adjusted analyses for confounding factors, including gender, ethnicity, handedness, maternal social class at recruitment, maternal age, maternal history of depression and maternal education. Results: There was a positive association between IQ at age 8 years and lifetime manic features at age 22–23 years (Pearson's correlation coefficient 0.159 (95% CI 0.120–0.198), P>0.001). Individuals in the lowest decile of manic features had a mean full-scale IQ (FSIQ) which was almost 10 points lower than those in the highest decile of manic features: mean FSIQ 100.71 (95% CI 98.74–102.6) v. 110.14 (95% CI 107.79–112.50), P>0.001. The association between IQ and manic features was present for FSIQ, VIQ and for PIQ but was strongest for VIQ. Conclusions: A higher childhood IQ score, and high VIQ in particular, may represent a marker of risk for the later development of bipolar disorder. This finding has implications for understanding of how liability to bipolar disorder may have been selected through generations. It will also inform future genetic studies at the interface of intelligence, creativity and bipolar disorder and is relevant to the developmental trajectory of bipolar disorder. It may also improve approaches to earlier detection and treatment of bipolar disorder in adolescents and young adults

    Serendipitous discovery of a strong-lensed galaxy in integral field spectroscopy from MUSE

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    2MASX J04035024-0239275 is a bright red elliptical galaxy at redshift 0.0661 that presents two extended sources at 2\arcsec~to the north-east and 1\arcsec~to the south-west. The sizes and surface brightnesses of the two blue sources are consistent with a gravitationally-lensed background galaxy. In this paper we present MUSE observations of this galaxy from the All-weather MUse Supernova Integral-field Nearby Galaxies (AMUSING) survey, and report the discovery of a background lensed galaxy at redshift 0.1915, together with other 15 background galaxies at redshifts ranging from 0.09 to 0.9, that are not multiply imaged. We have extracted aperture spectra of the lens and all the sources and fit the stellar continuum with STARLIGHT to estimate their stellar and emission line properties. A trace of past merger and active nucleus activity is found in the lensing galaxy, while the background lensed galaxy is found to be star-forming. Modeling the lensing potential with a singular isothermal ellipsoid, we find an Einstein radius of 1\farcs45±\pm0\farcs04, which corresponds to 1.9 kpc at the redshift of the lens and it is much smaller than its effective radius (reff∼r_{\rm eff}\sim 9\arcsec). Comparing the Einstein mass and the STARLIGHT stellar mass within the same aperture yields a dark matter fraction of 18%±818 \% \pm 8 \% within the Einstein radius. The advent of large surveys such as the Large Synoptic Survey Telescope (LSST) will discover a number of strong-lensed systems, and here we demonstrate how wide-field integral field spectroscopy offers an excellent approach to study them and to precisely model lensing effects.Comment: 12 pages, 12 Figures, 4 Tables. Accepted in MNRA

    Estimating the cost-effectiveness of brief interventions for heavy drinking in primary health care across Europe

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    Background Screening and Brief Interventions for alcohol are an effective public health measure to tackle alcohol-related harm, however relatively few countries across the European Union (EU) have implemented them widely. This may be due to a lack of understanding of the specific financial implications of such policies within each country. Methods A novel ‘meta-modelling’ approach was developed based on previous SBI cost-effectiveness models for four EU countries. Data was collected on the key factors which drive cost-effectiveness for all 28 EU countries (mean per capita alcohol consumption, proportion of the population to be screened over a 10-year SBI programme; per capita alcohol-attributable mortality; per capita alcoholattributable morbidity; mean cost of an alcohol-related hospitalisation and mean SBI-delivery staff cost). Regression analysis was used to fit two meta-models estimating net programme costs and quality-adjusted life-years (QALYs) gained, to calculate cost-effectiveness estimates specific to each EU country. Results Costs are dependent upon the proportion of the population covered by the screening programme, the country-specific per capita mortality and morbidity rate and the country-specific costs of GP care and hospitalisation. QALYs depend on the proportion of the population screened and per capita alcohol consumption. Despite large inter-country variability in factor values, SBI programmes are likely to be cost-effective in 24 out of 28 EU countries and cost-saving in about 50% of countries. Conclusion Implementing national programmes of SBI in primary health care would be a cost-effective means of reducing alcohol-attributable morbidity and deaths in almost all countries of the EU

    Estrogen administered after cardiac arrest and cardiopulmonary resuscitation ameliorates acute kidney injury in a sex- and age-specific manner

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    INTRODUCTION: There is a sex difference in the risk of ischemic acute kidney injury (AKI), and estrogen mediates the protective effect of female sex. We previously demonstrated that preprocedural chronic restoration of physiologic estrogen to ovariectomized female mice ameliorated AKI after cardiac arrest and cardiopulmonary resuscitation (CA/CPR). In the present study, we hypothesized that male mice and aged female mice would benefit from estrogen administration after CA/CPR. We tested the effect of estrogen in a clinically relevant manner by administrating it after CA/CPR. METHODS: CA/CPR was performed in young (10-15 weeks), middle-aged (43-48 weeks), and aged (78-87 weeks) C57BL/6 male and female mice. Mice received intravenous 17β-estradiol or vehicle 15 min after resuscitation. Serum chemistries and unbiased stereological assessment of renal injury were completed 24 h after CA. Regional renal cortical blood flow was measured by a laser Doppler, and renal levels of estrogen receptor alpha (ERα) and G protein-coupled estrogen receptor (GPER) were evaluated with immunoblotting. RESULTS: Post-arrest estrogen administration reduced injury in young males without significant changes in renal blood flow (percentage reduction compared with vehicle: serum urea nitrogen, 30 %; serum creatinine (sCr), 41 %; volume of necrotic tubules (VNT), 31 %; P < 0.05). In contrast, estrogen did not affect any outcomes in young females. In aged mice, estrogen significantly reduced sCr (80 %) and VNT (73 %) in males and VNT (51 %) in females. Serum estrogen levels in aged female mice after CA/CPR were the same as levels in male mice. With age, renal ERα was upregulated in females. CONCLUSIONS: Estrogen administration after resuscitation from CA ameliorates renal injury in young males and aged mice in both sexes. Because injury was small, young females were not affected. The protective effect of exogenous estrogen may be detectable with loss of endogenous estrogen in aged females and could be mediated by differences in renal ERs. Post-arrest estrogen administration is renoprotective in a sex- and age-dependent manner
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