Nonlocal Modeling in High-Velocity Impact Failure of 6061-T6 Aluminum

In this paper, we present numerical simulations with local and nonlocal models under dynamic loading conditions. We show that for finite element (FE) computations of high-velocity, impact problems with softening material models will result in spurious post-bifurcation mesh dependency solutions. To alleviate numerical instability associated within the post-bifurcation regime, a characteristic length scale was added to the constitutive relations based on calibration of the series of different notch specimen tests. This work aims to assess the practical relevance of the modified model to yield mesh independent results in the numerical simulations of high-velocity impact problems. To this end, we consider the problem of a rigid projectile moving at a range of velocities between 89-107 m/s, colliding against a 6061-T6 Aluminum disk. A material model embedded with a characteristic length scale in the manner proposed by Pijaudier-Cabot and Bazant (1987), but in the context of concrete damage, was utilized to describe the damage response of the disk. The numerical result shows that the addition of a characteristic length scale to the constitutive model does eliminate the pathological mesh dependency and shows excellent agreements between numerical and experimental results. Furthermore, the application of a nonlocal model for higher strain rate behavior shows the ability of the model to address intense localized deformations, irreversible flow, softening, and final failure

Avaliação do potencial produtivo da videira Niágara Rosada na Região de Pelotas.

O Objetivo do trabalho é avaliar a produção de videira ?Niágara Rosada? na região de Pelotas, com e sem a utilização da cobertura da parreiral com plástico transparente

Bidirectional associations between psychosocial well-being and body mass index in European children : longitudinal findings from the IDEFICS study

Background: The negative impact of childhood overweight on psychosocial well-being has been demonstrated in a number of studies. There is also evidence that psychosocial well-being may influence future overweight. We examined the bidirectional association between childhood overweight and psychosocial well-being in children from a large European cohort. The dual aim was to investigate the chronology of associations between overweight and psychosocial health indicators and the extent to which these associations may be explained by parental education. Methods: Participants from the IDEFICS study were recruited from eight countries between September 2007 and June 2008 when the children were aged 2 to 9.9 years old. Children and families provided data on lifestyle, psychosocial well-being, and measured anthropometry at baseline and at follow-up 2 years later. This study includes children with weight, height, and psychosocial well-being measurements at both time points (n = 7,831). Psychosocial well-being was measured by the KINDL (R) and Strengths and Difficulties Questionnaire respectively. The first instrument measures health-related quality of life including emotional well-being, self-esteem, parent relations and social relations while the second measures well-being based on emotional symptoms, conduct problems and peer-related problems. Logistic regression was used for modeling longitudinal associations. Results: Children who were overweight at baseline had increased risk of poor health-related quality of life (odds ratio (OR) = 1.23; 95 % confidence interval (CI): 1.03-1.48) measured 2 years later; this association was unidirectional. In contrast to health-related quality of life, poor well-being at baseline was associated with increased risk of overweight (OR = 1.39; 95 % CI: 1.03-1.86) at 2 year follow-up; this association was also only observed in one direction. Adjustment for parental education did not change our findings. Conclusion: Our findings indicate that the association between overweight and psychosocial well-being may be bidirectional but varies by assessment measures. Future research should further investigate which aspects of psychosocial well-being are most likely to precede overweight and which are more likely to be consequences of overweight

Pathological and ultrastructural analysis of surgical lung biopsies in patients with swine-origin influenza type A/H1N1 and acute respiratory failure

BACKGROUND: Cases of H1N1 and other pulmonary infections evolve to acute respiratory failure and death when co-infections or lung injury predominate over the immune response, thus requiring early diagnosis to improve treatment. OBJECTIVE: To perform a detailed histopathological analysis of the open lung biopsy specimens from five patients with ARDS with confirmed H1N1. METHODS: Lung specimens underwent microbiologic analysis, and examination by optical and electron microscopy. Immunophenotyping was used to characterize macrophages, natural killer, T and B cells, and expression of cytokines and iNOS. RESULTS: The pathological features observed were necrotizing bronchiolitis, diffuse alveolar damage, alveolar hemorrhage and abnormal immune response. Ultrastructural analysis showed viral-like particles in all cases. CONCLUSIONS: Viral-like particles can be successfully demonstrated in lung tissue by ultrastructural examination, without confirmation of the virus by RT-PCR on nasopharyngeal aspirates. Bronchioles and epithelium, rather than endothelium, are probably the primary target of infection, and diffuse alveolar damage the consequence of the effect of airways obliteration and dysfunction on innate immunity, suggesting that treatment should be focused on epithelial repair.(CNPq) National Council for Scientific and Technological Development(FAPESP) São Paulo Research Foundatio

EQ-5D-3L Derived Population Norms for Health Related Quality of Life in Sri Lanka

Background Health Related Quality of Life (HRQoL) is an important outcome measure in health economic evaluation that guides health resource allocations. Population norms for HRQoL are an essential ingredient in health economics and in the evaluation of population health. The aim of this study was to produce EQ-5D-3L-derived population norms for Sri Lanka. Method A population sample (n =  780) was selected from four districts of Sri Lanka. A stratified cluster sampling approach with probability proportionate to size was employed. Twenty six clusters of 30 participants each were selected; each participant completed the EQ-5D-3L in a face-to-face interview. Utility weights for their EQ-5D-3L health states were assigned using the Sri Lankan EQ-5D-3L algorithm. The population norms are reported by age and socio-economic variables. Results The EQ-5D-3L was completed by 736 people, representing a 94% response rate. Sixty per cent of the sample reported being in full health. The percentage of people responding to any problems in the five EQ-5D-3L dimensions increased with age. The mean EQ-5D-3L weight was 0.85 (SD 0.008; 95%CI 0.84-0.87). The mean EQ-5D-3L weight was significantly associated with age, housing type, disease experience and religiosity. People above 70 years of age were 7.5 times more likely to report mobility problems and 3.7 times more likely to report pain/discomfort than those aged 18-29 years. Those with a tertiary education were five times less likely to report any HRQoL problems than those without a tertiary education. A person living in a shanty was 4.3 more likely to have problems in usual activities than a person living in a single house. Conclusion The population norms in Sri Lanka vary with socio-demographic characteristics. The socioeconomically disadvantaged have a lower HRQoL. The trends of population norms observed in this lower middle income country were generally similar to those previously reported in high income countries

Validation of a model for static and dynamic recrystallization in metals

In this paper, modifications are proposed to a phenomenological plasticity model to account for the evolution of recrystallization and the resultant softening behavior. The novel model includes internal state variables representing dislocation density and the spacing between geometrically necessary subgrain boundaries. In order to capture both single and multiple peak recrystallization, the model tracks the evolution of recrystallized volume fractions for multiple cycles of recrystallization, and has a set of state variables for each volume fraction. A rule of mixtures is used to determine the average stress. The model is capable of capturing static recrystallization as well as both single and multiple peak dynamic recrystallization. Material parameters are fit to data from monotonic compression tests on copper for a wide range of temperatures and strain rates. The model is then validated by using the same parameter set to predict multiple-stage response in which samples are compressed, held at temperature for various lengths of time, and then compressed further. The model predicts both the static recrystallization that occurs between loading stages as well as the dynamic recrystallization occurring during the second loading stage