Tabu search for global optimization of continuous functions with application to phase equilibrium calculations

10.1016/S0098-1354(03)00134-0Computers and Chemical Engineering27111665-1679CCEN

Cardiovascular mortality following liver transplantation: predictors and temporal trends over 30 years

Aims There has been significant evolution in operative and post-transplant therapies following liver transplantation (LT). We sought to study their impact on cardiovascular (CV) mortality, particularly in the longer term. Methods and results A retrospective cohort study was conducted of all adult LTs in Australia and New Zealand across three 11-year eras from 1985 to assess prevalence, modes, and predictors of early (≤30 days) and late (>30 days) CV mortality. A total of 4265 patients were followed-up for 37 409 person-years. Overall, 1328 patients died, and CV mortality accounted for 228 (17.2%) deaths. Both early and late CV mortality fell significantly across the eras (P < 0.001). However, CV aetiologies were consistently the leading cause of early mortality and accounted for ∼40% of early deaths in the contemporary era. Cardiovascular deaths occurred significantly later than non-cardiac aetiologies (8.8 vs. 5.2 years, P < 0.001). On multivariable Cox regression, coronary artery disease [hazard ratio (HR) 4.6, 95% confidence interval (CI) 1.2-21.6; P = 0.04] and era of transplantation (HR 0.44; 95% CI 0.28-0.70; P = 0.01) were predictors of early CV mortality, while advancing age (HR 1.05, 95% CI 1.02-1.10; P = 0.005) was an independent predictors of late CV mortality. Most common modes of CV death were cardiac arrest, cerebrovascular events, and myocardial infarction. Conclusion Despite reductions in CV mortality post-LT over 30 years, they still account for a substantial proportion of early and late deaths. The late occurrence of CV deaths highlights the importance of longitudinal follow-up to study the efficacy of targeted risk-reduction strategies in this unique patient population.Anoop N Koshy, Paul J Gow, Hui-Chen Han, Andrew W Teh, Robert Jones, Adam Testro ... et al

Chinese high-school students in physics classroom as active, self-regulated learners: cognitive, motivational and environmental aspects

The present study investigates whether Chinese high-school students are self-regulated learners. A social-cognitive model that distinguishes environmental, motivational, and cognitive components of this active approach to learning is described. This provides an appropriate framework for investigating this complex issue with eighth and tenth graders attending a high-school in Beijing. By contrasting components of selfregulated learning and components indicating a more passive approach to learning that were both measured with self-report instruments, it could be shown that these students may indeed be considered as self-regulated physics learners. Comparisons of the grade levels revealed that tenth graders are not more active in self-regulating their learning processes than are eighth graders, and that they might even experience a motivational decline in learning physics. The same applies to girls versus boys. The physics-related self-efficacy belief of girls turned out to be considerably lower than with boys, a result that corresponds to findings with students from Western nations. Finally, assumptions about the causal role of motivational factors for using self-regulatory strategies could be confirmed. Possible consequences for further fostering self-regulated learning in physics instruction are discussed

A study of equation-solving and gibbs free energy minimization methods for phase equilibrium calculations

10.1205/026387602320776821Chemical Engineering Research and Design807745-759CERD

Latin American Journal of Solids and Structures

The Updated Lagrangian formulation for non-linear finite element analysis is applied to the problem of thin-walled composites box beams undergoing large displacements. A shear correction factor for thin-closed rectangular sections is introduced into some terms of the variational formulation and its influence in the results is analyzed, in both linear and non-linear problems. The Vlasov's theory describing the coupled flexural-torsional phenomenon and the implementation of the FSDT theory in thin-walled beams is discussed, as well as the strains, stress resultants and constitutive relationships for composites box beams. The application of the Mechanic of Laminated Beam theory (MLB) to the calculation of the shear correction factors considering more constitutive terms for computing the shear flow in flanges and webs than those ones used in the original theory is also debated. The Updated Lagrangian finite element model applied in this work for non-linear analysis of box beams is described. A comparison of the numerical results with those obtained experimentally, analytically and by the numerical models proposed by other authors is done for both linear and non-linear problems. The assumptions made in this work and the formulation developed only applies to thin-walled beams that undergo large displacements, but small to moderate twist rotations

Functional susceptibility of tropical forests to climate change

Tropical forests are some of the most biodiverse ecosystems in the world, yet their functioning is threatened by anthropogenic disturbances and climate change. Global actions to conserve tropical forests could be enhanced by having local knowledge on the forestsʼ functional diversity and functional redundancy as proxies for their capacity to respond to global environmental change. Here we create estimates of plant functional diversity and redundancy across the tropics by combining a dataset of 16 morphological, chemical and photosynthetic plant traits sampled from 2,461 individual trees from 74 sites distributed across four continents together with local climate data for the past half century. Our findings suggest a strong link between climate and functional diversity and redundancy with the three trait groups responding similarly across the tropics and climate gradient. We show that drier tropical forests are overall less functionally diverse than wetter forests and that functional redundancy declines with increasing soil water and vapour pressure deficits. Areas with high functional diversity and high functional redundancy tend to better maintain ecosystem functioning, such as aboveground biomass, after extreme weather events. Our predictions suggest that the lower functional diversity and lower functional redundancy of drier tropical forests, in comparison with wetter forests, may leave them more at risk of shifting towards alternative states in face of further declines in water availability across tropical regions