197 research outputs found

    Development of Casbar: a Two-phase Flow Code for the Interior Ballistics Problem

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    Accurate modelling of gun interior ballistic processes aids in the design and analysis of guns and their propelling charges. Presently, the most accurate modelling of the interior ballistics problem is provided by two-phase, multidimensional computational fluid dynamics (CFD) codes. We present our development of a CFD code, Casbar, which solves a two-phase (gas/particulate) flow problem in axisymmetric geometries. Our model is based on the governing equations for two-phase flow derived from separated flow theory. A finite-volume discretisation of the governing equations is used. The resulting set of equations is solved with a timestep-splitting approach based on the separation of various physical processes. We also present the modelling for the component physics such as propellant combustion and interphase drag. In addition, the solver includes the motion of the projectile and its influence on the flow dynamics. The capabilities of the code are demonstrated with some verification exercises

    Analyzing Recent Coronary Heart Disease Mortality Trends in Tunisia between 1997 and 2009.

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    BACKGROUND: In Tunisia, Cardiovascular Diseases are the leading causes of death (30%), 70% of those are coronary heart disease (CHD) deaths and population studies have demonstrated that major risk factor levels are increasing. OBJECTIVE: To explain recent CHD trends in Tunisia between 1997 and 2009. METHODS: DATA SOURCES: Published and unpublished data were identified by extensive searches, complemented with specifically designed surveys. ANALYSIS: Data were integrated and analyzed using the previously validated IMPACT CHD policy model. Data items included: (i)number of CHD patients in specific groups (including acute coronary syndromes, congestive heart failure and chronic angina)(ii) uptake of specific medical and surgical treatments, and(iii) population trends in major cardiovascular risk factors (smoking, total cholesterol, systolic blood pressure (SBP), body mass index (BMI), diabetes and physical inactivity). RESULTS: CHD mortality rates increased by 11.8% for men and 23.8% for women, resulting in 680 additional CHD deaths in 2009 compared with the 1997 baseline, after adjusting for population change. Almost all (98%) of this rise was explained by risk factor increases, though men and women differed. A large rise in total cholesterol level in men (0.73 mmol/L) generated 440 additional deaths. In women, a fall (-0.43 mmol/L), apparently avoided about 95 deaths. For SBP a rise in men (4 mmHg) generated 270 additional deaths. In women, a 2 mmHg fall avoided 65 deaths. BMI and diabetes increased substantially resulting respectively in 105 and 75 additional deaths. Increased treatment uptake prevented about 450 deaths in 2009. The most important contributions came from secondary prevention following Acute Myocardial Infarction (AMI) (95 fewer deaths), initial AMI treatments (90), antihypertensive medications (80) and unstable angina (75). CONCLUSIONS: Recent trends in CHD mortality mainly reflected increases in major modifiable risk factors, notably SBP and cholesterol, BMI and diabetes. Current prevention strategies are mainly focused on treatments but should become more comprehensive

    The Fundamental Diagram of Pedestrian Movement Revisited

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    The empirical relation between density and velocity of pedestrian movement is not completely analyzed, particularly with regard to the `microscopic' causes which determine the relation at medium and high densities. The simplest system for the investigation of this dependency is the normal movement of pedestrians along a line (single-file movement). This article presents experimental results for this system under laboratory conditions and discusses the following observations: The data show a linear relation between the velocity and the inverse of the density, which can be regarded as the required length of one pedestrian to move. Furthermore we compare the results for the single-file movement with literature data for the movement in a plane. This comparison shows an unexpected conformance between the fundamental diagrams, indicating that lateral interference has negligible influence on the velocity-density relation at the density domain 1m2<ρ<5m21 m^{-2}<\rho<5 m^{-2}. In addition we test a procedure for automatic recording of pedestrian flow characteristics. We present preliminary results on measurement range and accuracy of this method.Comment: 13 pages, 9 figure

    Modelling Future Coronary Heart Disease Mortality to 2030 in the British Isles.

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    OBJECTIVE: Despite rapid declines over the last two decades, coronary heart disease (CHD) mortality rates in the British Isles are still amongst the highest in Europe. This study uses a modelling approach to compare the potential impact of future risk factor scenarios relating to smoking and physical activity levels, dietary salt and saturated fat intakes on future CHD mortality in three countries: Northern Ireland (NI), Republic of Ireland (RoI) and Scotland. METHODS: CHD mortality models previously developed and validated in each country were extended to predict potential reductions in CHD mortality from 2010 (baseline year) to 2030. Risk factor trends data from recent surveys at baseline were used to model alternative future risk factor scenarios: Absolute decreases in (i) smoking prevalence and (ii) physical inactivity rates of up to 15% by 2030; relative decreases in (iii) dietary salt intake of up to 30% by 2030 and (iv) dietary saturated fat of up to 6% by 2030. Probabilistic sensitivity analyses were then conducted. RESULTS: Projected populations in 2030 were 1.3, 3.4 and 3.9 million in NI, RoI and Scotland respectively (adults aged 25-84). In 2030: assuming recent declining mortality trends continue: 15% absolute reductions in smoking could decrease CHD deaths by 5.8-7.2%. 15% absolute reductions in physical inactivity levels could decrease CHD deaths by 3.1-3.6%. Relative reductions in salt intake of 30% could decrease CHD deaths by 5.2-5.6% and a 6% reduction in saturated fat intake might decrease CHD deaths by some 7.8-9.0%. These projections remained stable under a wide range of sensitivity analyses. CONCLUSIONS: Feasible reductions in four cardiovascular risk factors (already achieved elsewhere) could substantially reduce future coronary deaths. More aggressive polices are therefore needed in the British Isles to control tobacco, promote healthy food and increase physical activity

    Inside the eco-home: using video to understand the implications of innovative housing

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    As a method of qualitative research, video offers a means of looking into the world of a respondent and a means of stimulating a dialogue, both with the respondent and others. Video requires, however, the application of additional ethical procedures and may also increase refusal rates, if it is publicly disseminated. Applied to the home, the use of video reveals both practice and identity. Video records practice, showing how the spaces within a home are used at a particular time. For this reason, video is well adapted to understanding the implications of living in a home with an innovative design and technology, with all the complexities that this commonly involves. Equally, video communicates the appearance of the home and of its occupants to whoever is watching. Video is, therefore, intimately connected to identity and the home as a place

    Decreasing trends in cardiovascular mortality in Turkey between 1988 and 2008.

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    BACKGROUND: Cardiovascular disease (CVD) mortality increased in developed countries until the 1970s then started to decline. Turkey is about to complete its demographic transition, which may also influence mortality trends. This study evaluated trends in coronary heart disease (CHD) and stroke mortality between 1988 and 2008. METHODS: The number of deaths by cause (ICD-8), age and sex were obtained from the Turkish Statistical Institute (TurkStat) annually between 1988 and 2008. Population statistics were based on census data (1990 and 2000) and Turkstat projections. European population standardised mortality rates for CHD and stroke were calculated for men and women over 35 years old. Joinpoint Regression was used to identify the points at which a statistically significant (p < 0.05) change of the trend occurred. RESULTS: The CHD mortality rate increased by 2.9% in men and 2.0% in women annually from 1988 to 1994, then started to decline. The annual rate of decline for men was 1.7% between 1994-2008, whilst in women it was 2.8% between 1994-2000 and 6.7% between 2005-2008 (p < 0.05 for all periods).Stroke mortality declined between 1990-1994 (annual fall of 3.8% in both sexes), followed by a slight increase between 1994-2004 (0.6% in men, 1.1% in women), then a further decline until 2008 (annual reduction of 4.4% in men, 7.9% in women) (p < 0.05 for all periods). CONCLUSIONS: A decrease in CVD mortality was observed from 1995 onwards in Turkey. The causes need to be explored in detail to inform future policy priorities in noncommunicable disease control

    <i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

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    Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

    Changes in Dietary Fat Intake and Projections for Coronary Heart Disease Mortality in Sweden: A Simulation Study.

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    OBJECTIVE: In Sweden, previous favourable trends in blood cholesterol levels have recently levelled off or even increased in some age groups since 2003, potentially reflecting changing fashions and attitudes towards dietary saturated fatty acids (SFA). We aimed to examine the potential effect of different SFA intake on future coronary heart disease (CHD) mortality in 2025. METHODS: We compared the effect on future CHD mortality of two different scenarios for fat intake a) daily SFA intake decreasing to 10 energy percent (E%), and b) daily SFA intake rising to 20 E%. We assumed that there would be moderate improvements in smoking (5%), salt intake (1g/day) and physical inactivity (5% decrease) to continue recent, positive trends. RESULTS: In the baseline scenario which assumed that recent mortality declines continue, approximately 5,975 CHD deaths might occur in year 2025. Anticipated improvements in smoking, dietary salt intake and physical activity, would result in some 380 (-6.4%) fewer deaths (235 in men and 145 in women). In combination with a mean SFA daily intake of 10 E%, a total of 810 (-14%) fewer deaths would occur in 2025 (535 in men and 275 in women). If the overall consumption of SFA rose to 20 E%, the expected mortality decline would be wiped out and approximately 20 (0.3%) additional deaths might occur. CONCLUSION: CHD mortality may increase as a result of unfavourable trends in diets rich in saturated fats resulting in increases in blood cholesterol levels. These could cancel out the favourable trends in salt intake, smoking and physical activity

    Portuguese emigration to Angola (2000-2015): Strengthening a specific postcolonial relationship in a new global framework?

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    Outflows to the Portuguese-speaking countries, although not dominant, played an important role in the growth of Portuguese emigration during the economic recession and austerity period, between 2010 and 2016. This chapter examines this migration process, considering that contemporary migration from Portugal to Angola is an example of reverse post-colonial migration within the framework of North-South movements. It presents the historical and socio-demographic background of Angola and some theoretical insights on the issue of North-South migration. The analyses of the migration process and the emigrants’ profiles rely in statistics and academic literature but especially on data gathered in a direct survey. Attention is given to indicators of integration, relations with Portugal and the post-colonial nature of the process. The profile of Portuguese in Angola shows an overrepresentation of highly skilled males over 35 years old, which migrated for professional reasons and sustain relations with Portugal through diverse transnational practices. This supports explanations for the emergence of North-South migration by appeal to economic expansion associated to the increasing insertion of several developing countries into global networks. However, the analysis fails to back up the hypothesis that Portuguese emigration to Angola is a form of reverse post-colonial migration based in ancestral return.info:eu-repo/semantics/publishedVersio
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