2,057 research outputs found

    Laser induced magnetization switching in films with perpendicular anisotropy: a comparison between measurements and a multi-macrospin model

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    Thermally-assisted ultra-fast magnetization reversal in a DC magnetic field for magnetic multilayer thin films with perpendicular anisotropy has been investigated in the time domain using femtosecond laser heating. The experiment is set-up as an optically pumped stroboscopic Time Resolved Magneto-Optical Kerr Effect magnetometer. It is observed that a modest laser fluence of about 0.3 mJ/square-cm induces switching of the magnetization in an applied field much less than the DC coercivity (0.8 T) on the sub-nanosecond time-scale. This switching was thermally-assisted by the energy from the femtosecond pump-pulse. The experimental results are compared with a model based on the Landau Lifschitz Bloch equation. The comparison supports a description of the reversal process as an ultra-fast demagnetization and partial recovery followed by slower thermally activated switching due to the spin system remaining at an elevated temperature after the heating pulse.Comment: 8 pages, 10 figures, to be submitted to PR

    The connection between single transverse spin asymmetries and the second moment of g2g_2

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    We point out that the size of the photon single spin asymmetry in high--energy proton proton collisions with one transversely polarized proton can be related to d(2)d^{(2)}, the twist three contribution to the second moment of g2g_2. Both quantities should be measured in the near future. The first was analysed by Qiu and Sterman, the second was estimated by Balitsky, Braun, and Kolesnichenko. Both experiments measure effectively the strength of the collective gluon field in the nucleon oriented relative to the nucleon spin. The sum rule results suggest that the single spin asymmetry is rather small for the proton, but could be substantial for the neutron.Comment: 6 pages, UFTP preprint 348/199

    Effect of polarized gluon distribution on spin asymmetries for neutral and charged pion production

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    A longitudinal double spin asymmetry for \pi^0 production has been measured by the PHENIX collaboration. The asymmetry is sensitive to the polarized gluon distribution and is indicated to be positive by theoretical predictions. We study a correlation between behavior of the asymmetry and polarized gluon distribution in neutral and charged pion production at RHIC.Comment: 7 pages, 5 eps figures, section added, typos corrected. to be published in PR

    Core excitations across the neutron shell gap in ÂČ⁰⁷Tl

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    The single closed-neutron-shell, one proton-hole nucleus 207Tl was populated in deep-inelastic collisions of a 208Pb beam with a 208Pb target. The yrast and near-yrast level scheme has been established up to high excitation energy, comprising an octupol

    Active surveillance of choroidal neovascularisation in children: incidence, aetiology and management findings from a national study in the UK

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    BACKGROUND/AIMS: To determine the UK incidence, demographics, aetiology, management and visual outcome for children developing choroidal neovascularisation (CNV). METHODS: A prospective population-based observational study of routine practice via the British Ophthalmological Surveillance Unit between January 2012 and December 2013 with subsequent 1-year follow-up in children under 16 years old with newly diagnosed CNV. RESULTS: Twenty-seven children with CNV were reported. The UK estimated annual incidence for those aged 16 and under was 0.21 per 100 000 (95% CI 0.133 to 0.299). The mean age was 11.1 years (SD 3.9, range 4-16). Fourteen were female. Seventy-seven per cent (22 patients) were Caucasian British. Twenty-three children (85%) had unilateral disease. The most common aetiology included inflammatory retinochoroidopathy (n=9), optic disc abnormalities (n=9) and idiopathic (n=5). Optical coherence tomography was performed in all cases and fundus fluorescein angiography in 61%. Management included observation only (n=10), anti-vascular endothelial growth factor (anti-VEGF) injection of bevacizumab (n=14) or ranibizumab (n=2), or both (n=1), and additional use of oral (n=1) and local (periocular n=2 and intravitreal n=2) steroids in five children with inflammatory retinochoroidopathy. The mean number of anti-VEGF injections was 2±1, with eight patients receiving only one injection. The mean (SD) best corrected visual acuity in LogMAR was 0.91 (0.53) at presentation and 0.74 (0.53) at 1-year follow-up (p=0.09). CONCLUSION: This is the first population-based prospective study of CNV in children. This is a rare disorder with a poor visual prognosis irrespective of CNV location and the use of anti-VEGF therapy

    Cognitive function and oral health among ageing adults

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    Objectives: There is inconclusive evidence that cognitive function is associated with oral health in older adults. This study investigated the association between cognitive function and oral health among older adults in England. Methods: This longitudinal cohort study included 4416 dentate participants aged 50 years or older in the English Longitudinal Study of Ageing during 2002‐2014. Cognitive function was assessed at baseline in 2002/2003 using a battery of cognitive function tests. The self‐reported number of teeth remaining and self‐rated general oral health status was reported in 2014/2015. Ordinal logistic regression was applied to model the association between cognitive function at baseline and tooth loss or self‐rated oral health. Results: Cognitive function at baseline was negatively associated with the risk of tooth loss (per each 1 standard deviation lower in cognitive function score, OR: 1.13, 95% CI: 1.05‐1.21). When cognitive function score was categorized into quintiles, there was a clear gradient association between cognitive function and tooth loss (P‐trend = 0.003); people in the lowest quintile of cognitive function had higher risk of tooth loss than those in the highest quintile (OR: 1.39, 95% CI: 1.12‐1.74). A similar magnitude and direction of association were evident between cognitive function and self‐rated oral health. Conclusion: This longitudinal study in an English ageing population has demonstrated that poor cognitive function at early stage was associated with poorer oral health and higher risk of tooth loss in later life. The gradient relationship suggests that an improvement in cognitive function could potentially improve oral health and reduce the risk of tooth loss in the ageing population

    HLA-A, -B, -C, -DRB1, DRB3, DRB4, DRB5 and DQB1 polymorphism detected by PCR-SSP in a semi-urban HIV-positive Ugandan population.

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    PCR-SSP was used to HLA-type a cohort of Ugandan HIV-positive individuals. The results represent a more comprehensive description of HLA in an African population than previously described and are in concordance with data from a general Black population. Substantial differences exist between this population and Caucasoid populations in which immunological responses to HIV have been investigated; this emphasises that the main HLA-restrictive elements for HIV-specific cytotoxic T lymphocytes will most likely be different for each population
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