782 research outputs found

    Application of Framingham risk estimates to ethnic minorities in United Kingdom and implications for primary prevention of heart disease in general practice : cross sectional population based study

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    Objective To compare the 10 year risk of coronary heart disease (CHD), stroke, and combined cardiovascular disease (CVD) estimated from the Framingham equations. Design Population based cross sectional survey. Setting Nine general practices in south London. Population 1386 men and women, age 40­59 years, with no history of CVD (475 white people, 447 south Asian people, and 464 people of African origin), and a subgroup of 1069 without known diabetes, left ventricular hypertrophy, peripheral vascular disease, renal impairment, or target organ damage. Main outcome measures 10 year risk estimates. Results People of African origin had the lowest 10 year risk estimate of CHD adjusted for age and sex (7.0%, 95% confidence interval 6.5 to 7.5) compared with white people (8.8%, 8.2 to 9.5) and south Asians (9.2%, 8.6 to 9.9) and the highest estimated risk of stroke (1.7% (1.5 to 1.9), 1.4% (1.3 to 1.6), 1.6% (1.5 to 1.8), respectively). The estimate risk of combined CVD, however, was highest in south Asians (12.5%, 11.6 to 13.4) compared with white people (11.9%, 11.0 to 12.7) and people of African origin (10.5%, 9.7 to 11.2). In the subgroup of 1069, the probability that a risk of CHD >15% would identify risk of combined CVD >20% was 91% in white people and 81% in both south Asians and people of African origin. The use of thresholds for risk of CHD of 12% in south Asians and 10% in people of African origin would increase the probability of identifying those at risk to 100% and 97%, respectively. Conclusion Primary care doctors should use a lower threshold of CHD risk when treating mild uncomplicated hypertension in people of African or south Asian origin

    POD-Based reduced order methods for optimal control problems governed by parametric partial differential equation with varying boundary control

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    In this work we propose tailored model order reduction for varying boundary optimal con-trol problems governed by parametric partial differential equations. With varying boundary control, we mean that a specific parameter changes where the boundary control acts on the system. This peculiar formulation might benefit from model order reduction. Indeed, fast and reliable simulations of this model can be of utmost usefulness in many applied fields, such as geophysics and energy engineering. However, varying boundary control features very complicated and diversified parametric behaviour for the state and adjoint variables. The state solution, for example, changing the boundary control parameter, might feature transport phenomena. Moreover, the problem loses its affine structure. It is well known that classical model order reduction techniques fail in this setting, both in accuracy and in efficiency. Thus, we propose reduced approaches inspired by the ones used when dealing with wave-like phenomena. Indeed, we compare standard proper orthogonal decomposi-tion with two tailored strategies: geometric recasting and local proper orthogonal decom-position. Geometric recasting solves the optimization system in a reference domain simpli-fying the problem at hand avoiding hyper-reduction, while local proper orthogonal decom-position builds local bases to increase the accuracy of the reduced solution in very general settings (where geometric recasting is unfeasible). We compare the various approaches on two different numerical experiments based on geometries of increasing complexity.& COPY; 2023 Elsevier Inc. All rights reserved

    Population dietary salt reduction and the risk of cardiovascular disease. A scientific statement from the European Salt Action Network

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    Abstract The publication in the last few years of a number of prospective observational studies suggesting a J-shaped association between levels of salt (sodium) consumption and cardiovascular outcomes has opened a debate on the pertinence of population-wide salt reduction policies to reduce cardiovascular disease burden, and some have even questioned the global World Health Organization guidelines, that recommend a 30% reduction in salt consumption by 2025, aiming at an ideal target of no more than 5 g of salt consumption per day. In September 2018 the European Salt Action Network (E.S.A.N.), after appraising the quality of publications questioning the appropriateness of population salt reduction, discussed the scientific evidence and identified the pitfalls of recent data. The new evidence was deemed inadequate and, in places, biased by flawed methodology. These were identified in the biased assessment of sodium intake from spot urine and the use of the Kawasaki formula, the biased assessment of the sodium–outcome relationships in prospective observational studies using spot urine samples, the impact of reverse causality in such studies, the inadequate analytical approaches to data analysis, the lack of biological plausibility and the lack of precision in assessing long-term salt consumption, as recently demonstrated in studies using more stringent quality features in their study designs. On the basis of such appraisal, the E.S.A.N. agreed a statement confirming the support to the implementation of national and regional programmes of moderate reduction in salt intake, as recommended by the World Health Organization

    Cluster galaxies 10 billion years ago

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    Cl J1449+0856 is a spectroscopically confirmed galaxy cluster at z ~ 2. The detection of a faint, extended X-ray emission, suggestive of an already evolved, partially relaxed structure, puts this system among the most distant "established” clusters rather than in the realm of z≳2 proto-clusters. This gives us a chance of studying galaxies in an evolved overdense environment very close to their formation epoch, and in particular to trace the evolution of early-type galaxies in clusters back to ten billion years ag

    Morphology of low-redshift compact galaxy clusters I. Shapes and radial profiles

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    The morphology of clusters of galaxies may be described with a set of parameters which contain information about the formation and evolutionary history of these systems. In this paper we present a preliminary study of the morphological parameters of a sample of 28 compact Abell clusters extracted from DPOSS data. The morphology of galaxy clusters is parameterized by their apparent ellipticity, position angle of the major axis, centre coordinates, core radius and beta-model power law index. Our procedure provides estimates of these parameters by simultaneously fitting them all, overcoming some of the difficulties induced by sparse data and low number statistics typical of this kind of analysis. The cluster parameters were fitted in a 3 x 3 h^-2 sqMpc region, measuring the background in a 2 <R< 2.5 h^-1Mpc annulus. We also explore the correlations between shape and profile parameters and other cluster properties. One third of this compact cluster sample has core radii smaller than 50 h^-1 kpc, i.e. near the limit that our data allow us to resolve, possibly consistent with cusped models. The remaining clusters span a broad range of core radii up to 750 h^-1 kpc. More than 80 per cent of this sample has ellipticity higher than 0.2. The alignment between the cluster and the major axis of the dominant galaxy is confirmed, while no correlation is observed with other bright cluster members. No significant correlation is found between cluster richness and ellipticity. Instead, cluster richness is found to correlate, albeit with large scatter, with the cluster core radius.[abridged]Comment: 23 pages, 17 figures, accepted for publication in MNRAS. Full paper including full resolution figures 2 and 9 at http://www.eso.org/~vstrazzu/P/ME1030fv.pd

    Formation epochs, star formation histories and sizes of massive early-type galaxies in cluster and field environments at z=1.2: insights from the rest-frame UV

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    We derive stellar masses, ages and star formation histories of massive early-type galaxies in the z=1.237 RDCS1252.9-2927 cluster and compare them with those measured in a similarly mass-selected sample of field contemporaries drawn from the GOODS South Field. Robust estimates of these parameters are obtained by comparing a large grid of composite stellar population models with 8-9 band photometry in the rest-frame NUV, optical and IR, thus sampling the entire relevant domain of emission of the different stellar populations. Additionally, we present new, deep UU-band photometry of both fields, giving access to the critical FUV rest-frame, in order to constrain empirically the dependence on the environment of the most recent star formation processes. We find that early-type galaxies, both in the cluster and in the field, show analogous optical morphologies, follow comparable mass vs. size relation, have congruent average surface stellar mass densities and lie on the same Kormendy relation. We also that a fraction of early-type galaxies in the field employ longer timescales, Ď„\tau, to assemble their mass than their cluster contemporaries. Hence we conclude that, while the formation epoch of early-type only depends on their mass, the environment does regulate the timescales of their star formation histories. Our deep UU-band imaging strongly supports this conclusions. It shows that cluster galaxies are at least 0.5 mag fainter than their field contemporaries of similar mass and optical-to-infrared colors, implying that the last episode of star formation must have happened more recently in the field than in the cluster.Comment: 20pages, 10 figures. to appear on Ap

    The Red Sequence of High-Redshift Clusters: a Comparison with Cosmological Galaxy Formation Models

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    We compare the results from a semi-analytic model of galaxy formation with spectro-photometric observations of distant galaxy clusters observed in the range 0.8< z< 1.3. We investigate the properties of their red sequence (RS) galaxies and compare them with those of the field at the same redshift. In our model we find that i) a well-defined, narrow RS is obtained already by z= 1.2; this is found to be more populated than the field RS, analogously to what observed and predicted at z=0; ii) the predicted U-V rest-frame colors and scatter of the cluster RS at z=1.2 have average values of 1 and 0.15 respectively, with a cluster-to-cluster variance of 0.2 and 0.06, respectively. The scatter of the RS of cluster galaxies is around 5 times smaller than the corresponding field value; iii) when the RS galaxies are considered, the mass growth histories of field and cluster galaxies at z=1.2 are similar, with 90 % of the stellar mass of RS galaxies at z=1.2 already formed at cosmic times t=2.5 Gyr, and 50 % at t=1 Gyr; v) the predicted distribution of stellar ages of RS galaxies at z=1.2 peaks at 3.7 Gyr for both cluster and field populations; however, for the latter the distribution is significantly skewed toward lower ages. When compared with observations, the above findings show an overall consistency, although the average value 0.07 of the observed cluster RS scatter (U-V colors) at z=1.2 is smaller than the corresponding model central value. We discuss the physical origin and the significance of the above results in the framework of cosmological galaxy formation.Comment: 14 pages, accepted for publication in ApJ. Updated one referenc
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