1,452 research outputs found

    Dryden: Royal Flush

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    Aspirin Resistance in Cardiovascular Disease: A Review

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    AbstractBackground. Aspirin is effective at reducing the cardiovascular event rate in defined patient groups. The introduction of antiplatelet therapies other than aspirin and the concept of aspirin resistance have led to critical reappraisal of current treatment. This review aims to clarify the evidence for aspirin resistance in patients with atherosclerosis.Methods. Medline search was performed to identify publications concerned with antiplatelet effects of aspirin and failure of aspirin therapy. Manual cross referencing was also performed.Results and conclusion. Wide variations in the rate of aspirin resistance (5.5–75%) have been reported. The lack of consensus on an appropriate definition and the number of different tests used to investigate aspirin resistance needs to be addressed. There are few studies where the primary aim was to document aspirin resistance or aspirin non-response. Further work should aim to investigate if aspirin resistance is clinically important and, if it is, what treatments may be beneficial to the at risk patient

    Studies of 49≤Z≤51 and N≥50 Nuclei at Intermediate Energies

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    This work was supported by National Science Foundation Grant PHY 75-00289 and Indiana Universit

    Radioactive Decay Studies of Nuclei Produced from Bombardment by Intermediate-Energy Neutrons

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    This work was supported by National Science Foundation Grant PHY 75-00289 and Indiana Universit

    Evaluation of the Theoretical Uncertainties in the Z to ll Cross Sections at the LHC

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    We study the sources of systematic errors in the measurement of the Z to ll cross-sections at the LHC. We consider the systematic errors in both the total cross-section and acceptance for anticipated experimental cuts. We include the best available analysis of QCD effects at NNLO in assessing the effect of higher order corrections and PDF and scale uncertainties on the theoretical acceptance. In addition, we evaluate the error due to missing NLO electroweak corrections and propose which MC generators and computational schemes should be implemented to best simulate the events.Comment: 23 pages, 52 eps figures, LaTeX with JHEP3.cls, epsfig. Added a reference, acknowledgment, and a few clarifying comments. 4/29: Changes in references, minor rewordings and misprint corrections, and one new table (Table 4) comparing CTEQ and MRST PDFs in the NNLO calculation. Version 6 adds email addresses and corrects one referenc

    Termination of a continent-margin upwelling system at the Permian-Triassic boundary (Opal Creek, Alberta, Canada)

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    Models of mass extinctions caused by greenhouse warming depend on the ability of warming to affect the oxygenation of the ocean, either through slowing circulation or changes in biological productivity and the organic carbon budget. Opal Creek, Alberta, Canada is a biostratigraphically continuous Permian–Triassic Boundary (PTB) section deposited in deep water on an outer shelf setting in the vast and understudied Panthalassic Ocean, along the western margin of Pangaea. The latest-Permian extinction is here represented as the disappearance of the previously dominant benthic fauna (siliceous sponges). On the basis of nitrogen and reduced sulfur isotopes as well as productivity-sensitive trace elements, the Middle Permian at Opal Creek is interpreted as a highly productive coastal upwelling zone where vigorous denitrification and sulfate reduction occurred in a mid-water oxygen minimum. Similar conditions appear to have continued into the latest Permian until the onset of a euxinic episode represented by a discrete pyrite bed and several trace element indicators of high productivity. This euxinic pulse is followed by the extinction of benthic fauna and a shift in nitrogen and sulfur isotopes to more normal marine values, suggesting the cessation of coastal upwelling and the consequent weakening of the mid-water oxygen minimum. The Lower Triassic appears to be a dysoxic, relatively unproductive environment with a bottom water oxygen minimum. Rhenium–osmium isotope systematics show a minimum of radiogenic Os near the main extinction event, which may be due to volcanic input, and increasingly radiogenic values approaching the PTB, possibly due to increased continental erosion. The Opal Creek system demonstrates that, while the biogeochemical crisis in the latest Permian was capable of impacting the coastal upwelling modality of ocean circulation, a transient increase in productivity likely drove the system toward euxinia and, ultimately, extinction

    Cortical beta oscillations are associated with motor performance following visuomotor learning

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    © 2019 The Authors People vary in their capacity to learn and retain new motor skills. Although the relationship between neuronal oscillations in the beta frequency range (15–30 Hz) and motor behaviour is well established, the electrophysiological mechanisms underlying individual differences in motor learning are incompletely understood. Here, we investigated the degree to which measures of resting and movement-related beta power from sensorimotor cortex account for inter-individual differences in motor learning behaviour in the young and elderly. Twenty young (18–30 years) and twenty elderly (62–77 years) healthy adults were trained on a novel wrist flexion/extension tracking task and subsequently retested at two different time points (45–60 min and 24 h after initial training). Scalp EEG was recorded during a separate simple motor task before each training and retest session. Although short-term motor learning was comparable between young and elderly individuals, there was considerable variability within groups with subsequent analysis aiming to find the predictors of this variability. As expected, performance during the training phase was the best predictor of performance at later time points. However, regression analysis revealed that movement-related beta activity significantly explained additional variance in individual performance levels 45–60 min, but not 24 h after initial training. In the context of disease, these findings suggest that measurements of beta-band activity may offer novel targets for therapeutic interventions designed to promote rehabilitative outcomes

    Emission spectra and intrinsic optical bistability in a two-level medium

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    Scattering of resonant radiation in a dense two-level medium is studied theoretically with account for local field effects and renormalization of the resonance frequency. Intrinsic optical bistability is viewed as switching between different spectral patterns of fluorescent light controlled by the incident field strength. Response spectra are calculated analytically for the entire hysteresis loop of atomic excitation. The equations to describe the non-linear interaction of an atomic ensemble with light are derived from the Bogolubov-Born-Green-Kirkwood-Yvon hierarchy for reduced single particle density matrices of atoms and quantized field modes and their correlation operators. The spectral power of scattered light with separated coherent and incoherent constituents is obtained straightforwardly within the hierarchy. The formula obtained for emission spectra can be used to distinguish between possible mechanisms suggested to produce intrinsic bistability.Comment: 18 pages, 5 figure

    A comparison of infant and toddler feeding practices of mothers with and without histories of eating disorders

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    This preliminary study surveyed the feeding practices of mothers with eating disorder histories through evaluation of mothers' reported feeding styles, child diet composition and restrictive special approaches to feeding. For this non-randomised cohort study, 25 mothers with eating disorder histories and 25 mothers with no history of an eating disorder with children ages 6-36 months were selected such that the groups were similar based on child age group and child sex. Mothers were compared on self-reported feeding style using the Infant Feeding Styles Questionnaire and on child diet composition and special feeding approaches using a modified version of the Toddler Diet Questionnaire from the Women, Infants, and Children program. Mothers with eating disorder histories scored lower on the restrictive feeding style subscale than controls. No significant differences were detected between groups in child diet including the percentage of mothers who breastfed, duration of breastfeeding, age at solid food introduction, daily number of meals or snacks or daily frequency of consumption of fruits, vegetables or protein foods. Mothers with eating disorder histories were more likely to report taking a restrictive special approach to feeding such as limiting processed foods or feeding organic foods only. Although mothers with eating disorder histories may not differ greatly from control mothers in terms of child diet composition (smaller effects may not have been detected due to limited sample size), they may be more likely to take restrictive special approaches to feeding which mirror dietary rules common in individuals with eating disorders
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