109 research outputs found

    Metal matrix composite analyzer (METCAN) user's manual, version 4.0

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    The Metal Matrix Composite Analyzer (METCAN) is a computer code developed at Lewis Research Center to simulate the high temperature nonlinear behavior of metal matrix composites. An updated version of the METCAN User's Manual is presented. The manual provides the user with a step by step outline of the procedure necessary to run METCAN. The preparation of the input file is demonstrated, and the output files are explained. The sample problems are presented to highlight various features of METCAN. An overview of the geometric conventions, micromechanical unit cell, and the nonlinear constitutive relationships is also provided

    Skeletal muscle mass and body fat in relation to successful ageing of older adults: The multi-national MEDIS study

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    BACKGROUND: The determinants that promote successful ageing still remain unknown. The aim of the present work was to evaluate the role of skeletal muscle mass and body fat percentage (BF%), in the level of successful ageing. METHODS: during 2005-2011, 2663 older (aged 65-100 years) from 21 Mediterranean islands and the rural Mani region (Peloponnesus) of Greece were voluntarily enrolled in the study. Appendicular skeletal muscle mass (ASM), skeletal muscle mass index (SMI) and BF% were calculated using population formulas. Dietary habits, energy intake, expenditure and energy balance were derived throughout standard procedures. A successful ageing index ranging from 0 to 10 was used. RESULTS: The mean ASM mass was 24±6.0kg, the SMI was 0.84±0.21 and the BF% was 44%. Females had lower SMI and higher BF% in comparison with males, respectively [(SMI: 0.66±0.09 vs. 1.03±0.11; BF%: 51% vs. 34%, (p<0.001)]. High successful agers had better rates in ASM (p=0.01), SMI (p<0.001) and BF% (p<0.001), compared with the medium and low successful ones. Changes in SMI [b-coefficient (95% CI):2.14 (1.57 to 2.71)] were positively associated with successful ageing, while changes in BF% [b-coefficient (95% CI): -0.04 (-0.05 to -0.03)] were inversely associated with successful ageing. Results from sensitivity analysis showed that the effects of variations on body composition were consistent, less pronounced in the positive energy balance group and more pronounced among the oldest old. CONCLUSIONS: Body composition changes seem to be associated with lower quality of life in the older adults, as measured through successful ageing

    Electronic structure and x-ray magnetic dichroism in random substitutional alloys of f-electron elements

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    The Koringa-Kohn-Rostoker —coherent-potential-approximation method combines multiple-scattering theory and the coherent-potential approximation to calculate the electronic structure of random substitutional alloys of transition metals. In this paper we describe the generalization of this theory to describe f-electron alloys. The theory is illustrated with a calculation of the electronic structure and magnetic dichroism curves for a random substitutional alloy containing rare-earth or actinide elements from first principles

    Effect of deferiprone or deferoxamine on right ventricular function in thalassemia major patients with myocardial iron overload

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    <p>Abstract</p> <p>Background</p> <p>Thalassaemia major (TM) patients need regular blood transfusions that lead to accumulation of iron and death from heart failure. Deferiprone has been reported to be superior to deferoxamine for the removal of cardiac iron and improvement in left ventricular (LV) function but little is known of their relative effects on the right ventricle (RV), which is being increasingly recognised as an important prognostic factor in cardiomyopathy. Therefore data from a prospective randomised controlled trial (RCT) comparing these chelators was retrospectively analysed to assess the RV responses to these drugs.</p> <p>Methods</p> <p>In the RCT, 61 TM patients were randomised to receive either deferiprone or deferoxamine monotherapy, and CMR scans for T2* and cardiac function were obtained. Data were re-analysed for RV volumes and function at baseline, and after 6 and 12 months of treatment.</p> <p>Results</p> <p>From baseline to 12 months, deferiprone reduced RV end systolic volume (ESV) from 37.7 to 34.2 mL (p = 0.008), whilst RV ejection fraction (EF) increased from 69.6 to 72.2% (p = 0.001). This was associated with a 27% increase in T2* (p < 0.001) and 3.1% increase in LVEF (p < 0.001). By contrast, deferoxamine showed no change in RVESV (38.1 to 39.1 mL, p = 0.38), or RVEF (70.0 to 69.9%, p = 0.93) whereas the T2* increased by 13% (p < 0.001), but with no change in LVEF (0.32%; p = 0.66). Analysis of between drugs treatment effects, showed significant improvements favouring deferiprone with a mean effect on RVESV of -1.82 mL (p = 0.014) and 1.16% for RVEF (p = 0.009). Using regression analysis the improvement in RVEF at 12 months was shown to be greater in patients with lower baseline EF values (p < 0.001), with a significant difference in RVEF of 3.5% favouring deferiprone over deferoxamine (p = 0.012).</p> <p>Conclusion</p> <p>In this retrospective analysis of a prospective RCT, deferiprone monotherapy was superior to deferoxamine for improvement in RVEF and end-systolic volume. This improvement in the RV volumes and function may contribute to the improved cardiac outcomes seen with deferiprone.</p

    Association between siesta (daytime sleep), dietary patterns and the presence of metabolic syndrome in elderly living in Mediterranean area (MEDIS study):The moderating effect of gender

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    Objectives: Several lifestyle parameters including diet, physical activity and sleep were associated in isolation with the presence of Metabolic Syndrome (MetS) in adults, to date there is a paucity of studies which evaluated their combined role aging populations and especially with respect to gender. Therefore, the aim of the present study was to provide a global consideration of the lifestyle factors associated with MetS among elderly individuals. Design: Cross-sectional observational study. Setting: 21 Mediterranean islands and the rural Mani region (Peloponnesus) of Greece. Participants: during 2005-2015, 2749 older (aged 65-100 years) from were voluntarily enrolled in the study. Measurements: Dietary habits, energy intake, physical activity status, sociodemographic characteristics, lifestyle parameters (sleeping and smoking habits) and clinical profile aspects were derived through standard procedures. The presence of MetS was defined using the definition provided by NCEP ATP III (revised) and cluster analysis was used to identify overall dietary habit patterns. Results: The overall prevalence of MetS in the study sample was 36.2%, but occurred more frequently in females (40.0% vs. 31.8%, respectively, p=0.03). Individuals with MetS were more likely to sleep during the day (89.4% vs. 76.8% respectively, p=0.039) and frequent ‘siesta’ was positively linked to the odds of MetS presence in females (Odds Ratio (OR) =3.43, 95% Confidence Intervals (CI): 1.08-10.9), but not for men (p=0.999). The lower carbohydrate (i.e., 45.2% of total daily energy, 120±16gr/day) dietary cluster was inversely associated with the odds for MetS presence, but only for men (OR=0.094, 95%CI: 0.010-0.883). Conclusions: Lifestyle parameters including sleep and diet quality are strongly associated with the presence of MetS in elderly cohort, but different their level of influence appears to be different, depending on gender. Further research is needed to better consider the role of lifestyle characteristics in the management of MetS in clinical practice

    Is Parental Longevity Associated With the Cardiovascular Risk and the Successful Aging of Their Offspring? Results From the Multinational MEDIS Study

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    The aim of the present study was to evaluate the role of parental longevity and parental cardiovascular disease (CVD) history in CVD risk and successful aging of a random sample of older adults living in the Mediterranean basin and who participated in the MEDiterranean Islands (MEDIS) study. During 2005 to 2011, 2663 elders were voluntarily enrolled. A multidimensional successful aging index consisting of 10 components was used. Paternal and maternal longevity was defined as those older participants of whom both parents lived above the age of 90. The burden of CVD-related factors (CVD-RFs) was calculated as the total score of 4 major CVD-RFs (range 0-4). After adjustment, parental longevity was inversely associated with the burden of CVD-RFs (P= .04). Moreover, parental longevity was positively associated with the older adults' successful aging score (β-coefficient [95% confidence interval]: .38 [0.06-0.71]). Parent's long living was revealed as an important factor for successful aging and for reduced CVD risk, suggesting that further research is needed in the genetic predisposition of longevity

    Anti-Inflammatory Nutrition and Successful Ageing in Elderly Individuals: The Multinational MEDIS Study

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    BACKGROUND: The role of diet and inflammation in successful ageing is not transparent, and as such, is still being investigated. The aim of the present work was to evaluate the inflammatory potential of dietary habits in the successful ageing of a random sample of older adults living in the Mediterranean basin and who participated in the MEDIS (MEDiterranean ISlands) study. METHODS: During 2005-2016, 3,128 older adults (aged 65-100 years) from 24 Mediterranean islands and the rural Mani region (Peloponnesus) of Greece were enrolled in the study. A multidimensional successful ageing index consisting of 10 components was employed. A validated and reproducible Food Frequency Questionnaire (FFQ) was used to evaluate the dietary habits of the older adults. A nutrition anti-inflammatory (NAI) score based on the participants' specific dietary habits was assessed. RESULTS: Participants with high NAI scores (proinflammatory nutrition) had a higher prevalence of hypercholesterolemia and lower levels of successful ageing. After adjusting for several confounders, the NAI score was associated with successful ageing (-0.03, 95% CI -0.5 to -0.006). Stratified analysis by gender and advanced age revealed heterogeneity in the NAI score, predicting successful ageing. CONCLUSIONS: The inflammatory potential of nutrition was reported as an important factor for successful ageing, suggesting that further research is needed on the role of anti- and proinflammatory dietary habits in healthy and successful ageing

    Modeling of synthesis and flow properties of propylene-diene copolymers

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    Copolymerization with nonconjugated dienes offers an attractive route for introducing long-chain branching in polypropylene. From a simplified set of rate equations for such copolymerization with a metallocene catalyst, we derive the probabilities of branch formation at different stages of the reaction in a semibatch reactor. Using these probabilities, we generate an ensemble of molecules via a Monte Carlo sampling. The knowledge of the branching topology and segment lengths allows us to compute the flow properties of the resins from computational rheology. We compare our model predictions with existing experimental data, namely the molar mass distribution and small amplitude oscillatory shear response, for a set of resins with varying diene content. The rheology data suggest that the entanglement time Ï.,e depends sensitively and in a well-defined fashion on the diene content

    Manganese nanoclusters and nanowires on GaAs surfaces

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    We have computed the local magnetic moments of manganese and neighboring arsenic for various cluster configurations on the (001) surface of GaAs bulk crystal using a cluster of 512 atoms. We obtained for manganese a substantial local magnetic moment of 3.66 Bohr magnetons for all cases considered. The induced magnetic moment of arsenic is less than that of manganese by two orders of magnitude and falls off drastically beyond nearest neighbor distance. A small amount of charge is transferred from the manganese to arsenic. The possibility of a spin polarized wire channel on the arsenic layer below the surface is suggested.Comment: 17 pages (includes 2 tables and 3 figures

    Agency, stewardship and the universal-family firm : a qualitative historical analysis

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    This paper introduces the idea of a non-kinship-based Universal-family firm, an organizational form we developed based on interpreting historical writings in their socio-economic context. We analyzed Luke’s gospel with an eye toward drawing implications for the stewardship-agency debate in the contemporary family business literature. Our paper makes contributions at two important levels. In addition to introducing and developing theory about the Universal-family firms, we also contribute to the methodological toolkit of family business scholars by providing a template for using historical documents to challenge, enhance and develop theory
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