1,296 research outputs found

    A short note on the nested-sweep polarized traces method for the 2D Helmholtz equation

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    We present a variant of the solver in Zepeda-N\'u\~nez and Demanet (2014), for the 2D high-frequency Helmholtz equation in heterogeneous acoustic media. By changing the domain decomposition from a layered to a grid-like partition, this variant yields improved asymptotic online and offline runtimes and a lower memory footprint. The solver has online parallel complexity that scales \emph{sub linearly} as O(NP)\mathcal{O} \left( \frac{N}{P} \right), where NN is the number of volume unknowns, and PP is the number of processors, provided that P=O(N1/5)P = \mathcal{O}(N^{1/5}). The variant in Zepeda-N\'u\~nez and Demanet (2014) only afforded P=O(N1/8)P = \mathcal{O}(N^{1/8}). Algorithmic scalability is a prime requirement for wave simulation in regimes of interest for geophysical imaging.Comment: 5 pages, 5 figure

    HbA1c in Nondiabetic Dutch Infants Aged 8–12 Months: The GECKO-Drenthe birth cohort study

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    OBJECTIVE-An international committee of experts recommended using HbA(1c) for diagnostic testing for diabetes. Little is known about normal values of HbA(1c) in infants. The aim of this study is to describe the distribution of HbA(1c) in 8- to 12-month-old nondiabetic infants. RESEARCH DESIGN AND METHODS-HbA(1c) was measured in 86 infants participating in the Groningen Expert Center for Kids with Obesity (GECKO)-Drenthe birth cohort study. Anthropometric measurements were performed at Well Baby Clinics. Data on parents and children were collected prospectively using questionnaires. RESULTS-HbA(1c) was normally distributed with a mean (SD) HbA(1c) level of 5.38% (0.24), range 4.8-6.0% or 35.29 mmol/mol (2.65), range 29.1-42.1 mmol/mol. Age, sex, birth weight, duration of breastfeeding, anthropometric measurements, and maternal BMI were not associated with HbA(1c). CONCLUSIONS-We found a normal distribution of HbA(1c) with a relatively high mean HbA(1c) of 5.38%. No significant association between risk factors for type 2 diabetes and HbA(1c) levels was found

    Peroxiredoxin 4, a novel circulating biomarker for oxidative stress and the risk of incident cardiovascular disease and all-cause mortality

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    BACKGROUND: Oxidative stress has been suggested to play a key role in the development of cardiovascular disease (CVD). The aim of our study was to investigate the associations of serum peroxiredoxin 4 (Prx4), a hydrogen peroxide-degrading peroxidase, with incident CVD and all-cause mortality. We subsequently examined the incremental value of Prx4 for the risk prediction of CVD compared with the Framingham risk score (FRS). METHODS AND RESULTS: We performed Cox regression analyses in 8141 participants without history of CVD (aged 28 to 75 years; women 52.6%) from the Prevention of Renal and Vascular End-stage Disease (PREVEND) study in Groningen, The Netherlands. Serum Prx4 was measured by an immunoluminometric assay in baseline samples. Main outcomes were: (1) incident CVD events or CVD mortality and (2) all-cause mortality during a median follow-up of 10.5 years. In total, 708 participants (7.8%) developed CVD events or CVD mortality, and 517 participants (6.3%) died. Baseline serum Prx4 levels were significantly higher in participants with incident CVD events or CVD mortality and in those who died than in participants who remained free of outcomes (both P<0.001). In multivariable models with adjustment for Framingham risk factors, hazard ratios were 1.16 (95% CI 1.06 to 1.27, P<0.001) for incident CVD events or CVD mortality and 1.17 (95% CI 1.06 to 1.29, P=0.003) for all-cause mortality per doubling of Prx4 levels. After the addition of Prx4 to the FRS, the net reclassification improvement was 2.7% (P=0.01) using 10-year risk categories of CVD. CONCLUSIONS: Elevated serum Prx4 levels are associated with a significantly higher risk of incident CVD events or CVD mortality and all-cause mortality after adjustment for clinical risk factors. The addition of Prx4 to the FRS marginally improved risk prediction of future CVD

    Thermally activated reorientation of di-interstitial defects in silicon

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    We propose a di-interstitial model for the P6 center commonly observed in ion implanted silicon. The di-interstitial structure and transition paths between different defect orientations can explain the thermally activated transition of the P6 center from low-temperature C1h to room-temperature D2d symmetry. The activation energy for the defect reorientation determined by ab initio calculations is 0.5 eV in agreement with the experiment. Our di-interstitial model establishes a link between point defects and extended defects, di-interstitials providing the nuclei for the growth.Comment: 12 pages, REVTeX, Four figures, submitted to Phys. Rev. Let

    Future of the drug label:Perspectives from a multistakeholder dialogue

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    'Regulating drugs does not end when market access has been granted. Monitoring drugs over the life-cycle has become state of the art, inherent to evolving legislation and societal need. Here, we explore how the drug label could move along in a changing playing-field, and become a sustainable label for the future. A dialogue between academia, government, the pharmaceutical industry, and patient/societal organizations was organized by the Regulatory Science Network Netherlands, RSNN. This is their view.

    Required duration of mass ivermectin treatment for onchocerciasis elimination in Africa: a comparative modelling analysis

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    Background: The World Health Organization (WHO) has set ambitious targets for the elimination of onchocerciasis by 2020-2025 through mass ivermectin treatment. Two different mathematical models have assessed the feasibility of reaching this goal for different settings and treatment scenarios, namely the individual-based microsimulation model ONCHOSIM and the population-based deterministic model EPIONCHO. In this study, we harmonize some crucial assumptions and compare model predictions on common outputs. Methods: Using a range of initial endemicity levels and treatment scenarios, we compared the models with respect to the following outcomes: 1) model-predicted trends in microfilarial (mf) prevalence and mean mf intensity during 25 years of (annual or biannual) mass ivermectin treatment; 2) treatment duration needed to bring mf prevalence below a provisional operational threshold for treatment interruption (pOTTIS, i.e. 1.4 %), and 3) treatment duration needed to drive the parasite population to local elimination, even in the absence of further interventions. Local elimination was judged by stochastic fade-out in ONCHOSIM and by reaching transmission breakpoints in EPIONCHO. Results: ONCHOSIM and EPIONCHO both predicted that in mesoendemic areas the pOTTIS can be reached with annual treatment, but that this strategy may be insufficient in very highly hyperendemic areas or would require prolonged continuation of treatment. For the lower endemicity levels explored, ONCHOSIM predicted that the time needed to reach the pOTTIS is longer than that needed to drive the parasite population to elimination, whereas for the higher endemicity levels the opposite was true. In EPIONCHO, the pOTTIS was reached consistently sooner than the breakpoint. Co
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