381 research outputs found

    Three-dimensional simulations of a starburst wind

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    In order to better understand the formation of a starburst-driven wind, we have performed a series of three-dimensional hydrodynamical simulations in an inhomogeneous interstellar medium. We present the results of these simulations, which provide new insights into the formation of the optical filaments and the origin of the soft X-ray emission

    Effect of Loading Condition on Traction Coefficient Between Shoes and Artificial Turf Surfaces

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    Background. The interaction between a shoe and a turf surface is highly complex and difficult to characterize. Over the three decades since artificial turf was introduced, researchers have attempted to understand the traction caused by the interaction. However, some of the methodologies used for traction measurements have not capitalized on advances in currently available technology for testing and most testing conditions have not simulated realistic physiological loads. Method of Approach. To assess the effect of test condition on traction results, the newly designed TurfBuster testing device was used to collect traction data on FieldTurfâ„¢ brand artificial turf under varying conditions. Four cleated athletic shoes were tested under eight different vertical loads ranging from 222-1780 N. The static, dynamic, and peak traction coefficient values were calculated and averaged over three trials for each shoe and condition. Results. In all but the lowest vertical load condition, the static traction coefficient was less than the dynamic traction coefficient. There was a distinct separation found between 666 N and 888 N loading conditions for all three variables measured. Below the load condition of 666 N only one significant difference was found in all comparisons across and within shoe styles. Above 888 N multiple differences were found across shoe styles, but differences were not found within a shoe style until a load of at least 1554 N. Conclusions. At loads below 666 N the cleats perform almost identically at all three variables measured, static, dynamic, and peak traction coefficients. At loads above 888 N, shoe traction was different among the cleat styles for all traction variables. However, at loads between 888 N and 1334 N there were no differences found within a shoe style. This implies that each shoe has no performance difference in loads representative of up to one bodyweight. Due to these results the measurement of traction characteristics between cleated shoes and FieldTurf should be conducted at a load of at least 888 N to determine differences across shoe styles and loads ranging from 888 N to at least 1554 N to determine individual shoe characteristics

    Starburst-Driven Galactic Winds: Filament Formation and Emission Processes

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    We have performed a series of three-dimensional simulations of the interaction of a supersonic wind with a non-spherical radiative cloud. These simulations are motivated by our recent three-dimensional model of a starburst-driven galactic wind interacting with an inhomogeneous disk, which show that an optically emitting filament can be formed by the break-up and acceleration of a cloud into a supersonic wind. In this study we consider the evolution of a cloud with two different geometries (fractal and spherical) and investigate the importance of radiative cooling on the cloud's survival. We have also undertaken a comprehensive resolution study in order to ascertain the effect of the assumed numerical resolution on the results. We find that the ability of the cloud to radiate heat is crucial for its survival. While an adiabatic cloud is destroyed over a short period of time, a radiative cloud is broken up via the Kelvin-Helmholtz instability into numerous small, dense cloudlets, which are drawn into the flow to form a filamentary structure. The degree of fragmentation is highly dependent on the resolution of the simulation, with the number of cloudlets formed increasing as the Kelvin-Helmholtz instability is better resolved. Nevertheless, there is a clear qualitative trend, with the filamentary structure still persistent at high resolution. We confirm the mechanism behind the formation of the H-alpha emitting filaments found in our global simulations of a starburst-driven wind. Based on our resolution study, we conclude that bow shocks around accelerated gas clouds, and their interaction, are the main source of the soft X-ray emission observed in these galactic-scale winds. [ABRIDGED]Comment: Accepted to ApJ, 39 pages, 21 figures, movie file can obtained at http://www.mso.anu.edu.au/~jcooper/movie/halpha.mo

    Women with diabetes are at increased relative risk of heart failure compared to men: Insights from UK Biobank

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    Aims: To investigate the effect of diabetes on mortality and incident heart failure (HF) according to sex, in the low risk population of UK Biobank. To evaluate potential contributing factors for any differences seen in HF end-point. Methods: The entire UK Biobank study population were included. Participants that withdrew consent or were diagnosed with diabetes after enrolment were excluded from the study. Univariate and multivariate cox regression models were used to assess endpoints of mortality and incident HF, with median follow-up periods of 9 years and 8 years respectively. Results: A total of 493,167 participants were included, hereof 22,685 with diabetes (4.6%). Two thousand four hundred fifty four died and 1,223 were diagnosed or admitted with HF during the follow up periods of 9 and 8 years respectively. Overall, the mortality and HF risk were almost doubled in those with diabetes compared to those without diabetes (hazard ratio (HR) of 1.9 for both mortality and heart failure) in the UK Biobank population. Women with diabetes (both types) experience a 22% increased risk of HF compared to men (HR of 2.2 (95% CI: 1.9-2.5) vs. 1.8 (1.7-2.0) respectively). Women with type 1 diabetes (T1DM) were associated with 88% increased risk of HF compared to men (HR 4.7 (3.6-6.2) vs. 2.5 (2.0-3.0) respectively), while the risk of HF for type 2 diabetes (T2DM) was 17% higher in women compared to men (2.0 (1.7-2.3) vs. 1.7 (1.6-1.9) respectively). The increased risk of HF in women was independent of confounding factors. The findings were similar in a model with all-cause mortality as a competing risk. This interaction between sex, diabetes and outcome of HF is much more prominent for T1DM (p = 0.0001) than T2DM (p = 0.1). Conclusion: Women with diabetes, particularly those with T1DM, experience a greater increase in risk of heart failure compared to men with diabetes, which cannot be explained by the increased prevalence of cardiac risk factors in this cohort

    The multiple sclerosis risk sharing scheme monitoring study - early results and lessons for the future

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    Background: Risk sharing schemes represent an innovative and important approach to the problems of rationing and achieving cost-effectiveness in high cost or controversial health interventions. This study aimed to assess the feasibility of risk sharing schemes, looking at long term clinical outcomes, to determine the price at which high cost treatments would be acceptable to the NHS. Methods: This case study of the first NHS risk sharing scheme, a long term prospective cohort study of beta interferon and glatiramer acetate in multiple sclerosis ( MS) patients in 71 specialist MS centres in UK NHS hospitals, recruited adults with relapsing forms of MS, meeting Association of British Neurologists (ABN) criteria for disease modifying therapy. Outcome measures were: success of recruitment and follow up over the first three years, analysis of baseline and initial follow up data and the prospect of estimating the long term cost-effectiveness of these treatments. Results: Centres consented 5560 patients. Of the 4240 patients who had been in the study for a least one year, annual review data were available for 3730 (88.0%). Of the patients who had been in the study for at least two years and three years, subsequent annual review data were available for 2055 (78.5%) and 265 (71.8%) patients respectively. Baseline characteristics and a small but statistically significant progression of disease were similar to those reported in previous pivotal studies. Conclusion: Successful recruitment, follow up and early data analysis suggest that risk sharing schemes should be able to deliver their objectives. However, important issues of analysis, and political and commercial conflicts of interest still need to be addressed

    Predictors of positive treatment outcome in people with anorexia nervosa treated in a specialized inpatient unit: The role of early response to treatment

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    o investigate factors which predict positive treatment outcome in inpatients with anorexia nervosa (AN), particularly the role of early treatment response. METHOD: 102 patients entering specialist inpatient treatment were assessed for eating disorder history, psychopathology and motivation to change. Predictive factors assessed were: early treatment response defined as weight increase of at least 0.5-1 kg/week during the first six weeks of treatment; admission BMI; onset age; chronicity; motivation to change; diagnosis; and previous hospitalization for AN. Positive treatment outcome was defined as achieving BMI 17.5 kg/m2 within an individual timeframe. RESULTS: Logistic regression indicated that patients were 18 times more likely to reach positive treatment outcome if they met NICE weight guidelines within the first six weeks of hospitalization. Higher admission BMI was also found to predict positive treatment outcome. DISCUSSION: Higher entry BMI and early weight gain predict positive treatment outcome in individuals receiving specialist AN inpatient treatment

    Three-Dimensional Simulations of a Starburst-Driven Galactic Wind

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    We have performed a series of three-dimensional simulations of a starburst-driven wind in an inhomogeneous interstellar medium. The introduction of an inhomogeneous disk leads to differences in the formation of a wind, most noticeably the absence of the ``blow-out'' effect seen in homogeneous models. A wind forms from a series of small bubbles that propagate into the tenuous gas between dense clouds in the disk. These bubbles merge and follow the path of least resistance out of the disk, before flowing freely into the halo. Filaments are formed from disk gas that is broken up and accelerated into the outflow. These filaments are distributed throughout a biconical structure within a more spherically distributed hot wind. The distribution of the inhomogeneous interstellar medium in the disk is important in determining the morphology of this wind, as well as the distribution of the filaments. While higher resolution simulations are required in order to ascertain the importance of mixing processes, we find that soft X-ray emission arises from gas that has been mass-loaded from clouds in the disk, as well as from bow shocks upstream of clouds, driven into the flow by the ram pressure of the wind, and the interaction between these shocks.Comment: 37 pages, 16 figures, mpg movie can be obtained at http://www.mso.anu.edu.au/~jcooper/movie/video16.mpg, accepted for publication in Ap

    Body Surface Area and Baseline Blood Pressure Predict Subclinical Anthracycline Cardiotoxicity in Women Treated for Early Breast Cancer

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    This work was supported by the United Kingdom Department of Health under the Pharmacogenetics Research programme (grant number PHGX23A).Background and aims: Anthracyclines are highly effective chemotherapeutic agents which may cause long-term cardiac damage (chronic anthracycline cardiotoxicity) and heart failure. The pathogenesis of anthracycline cardiotoxicity remains incompletely understood and individual susceptibility difficult to predict. We sought clinical features which might contribute to improved risk assessment. Methods: Subjects were women with early breast cancer, free of pre-existing cardiac disease. Left ventricular ejection fraction was measured using cardiovascular magnetic resonance before and >12 months after anthracycline-based chemotherapy (>3 months post-Trastuzumab). Variables associated with subclinical cardiotoxicity (defined as a fall in left ventricular ejection fraction of ≥5%) were identified by logistic regression. Results: One hundred and sixty-five women (mean age 48.3 years at enrollment) completed the study 21.7 months [IQR 18.0-26.8] after starting chemotherapy. All received anthracyclines (98.8% epirubicin, cumulative dose 400 [300-450] mg/m2); 18% Trastuzumab. Baseline blood pressure was elevated (≥140/90mmHg, mean 147.3/86.1mmHg) in 18 subjects. Thirty-four subjects (20.7%) were identified with subclinical cardiotoxicity, independent predictors of which were the number of anthracycline cycles (odds ratio, OR 1.64 [1.17-2.30] per cycle), blood pressure ≥140/90mmHg (OR 5.36 [1.73-17.61]), body surface area (OR 2.08 [1.36-3.20] per standard deviation (0.16m2) increase), and Trastuzumab therapy (OR 3.35 [1.18-9.51]). The resultant predictive-model had an area under the receiver operating characteristics curve of 0.78 [0.70-0.86]. Conclusions: We found subclinical cardiotoxicity to be common even within this low risk cohort. Risk of cardiotoxicity was associated with modestly elevated baseline blood pressure-indicating that close attention should be paid to blood pressure in patients considered for anthracycline based chemotherapy. The association with higher body surface area suggests that indexing of anthracycline doses to surface area may not be appropriate for all, and points to the need for additional research in this area

    Utility of genetic and non-genetic risk factors in prediction of type 2 diabetes: Whitehall II prospective cohort study

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    Objectives To assess the performance of a panel of common single nucleotide polymorphisms (genotypes) associated with type 2 diabetes in distinguishing incident cases of future type 2 diabetes (discrimination), and to examine the effect of adding genetic information to previously validated non-genetic (phenotype based) models developed to estimate the absolute risk of type 2 diabetes
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