• Interaction and multiscale mechanics
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• v.2 no.1
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• pp.31-44
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• 2009

While the classical theory of Griffith is the foundation of modern understanding of brittle fracture, it has a number of significant shortcomings: Griffith theory does not predict crack initiation and path and it suffers from the presence of unphysical stress singularities. In 1998, Francfort and Marigo presented an energy functional minimization method, where the crack (or its absence) as well as its path are part of the problem's solution. The energy functionals act on spaces of functions of bounded variations, where the cracks are related to the discontinuity sets of such functions. The new model presented here uses modified energy functionals to account for molecular interactions in the vicinity of crack tips, resulting in Barenblatt cohesive forces, such that the model becomes free of stress singularities. This is done in a physically consistent way using recently published concepts of Sinclair. Here, for the consistency of the model, it becomes necessary to allow for crack reversibility and to consider local minimizers of the energy functionals. The latter is achieved by introducing different time scales. The model is solved in its global as well as in its local version for a simple one-dimensional example, showing that local minimization is necessary to yield a physically reasonable result.

• Parasites, Hosts and Diseases
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• v.52 no.6
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• pp.639-644
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• 2014

Congenital malaria is assumed to be a risk factor for infant morbidity and mortality in endemic areas like Maumere, Indonesia. Infected infants are susceptible to its impact such as premature labor, low birth weight, anemia, and other unspecified symptoms. The aim of this study was to investigate the prevalence of congenital malaria and the influence of mother-infant paired parasite densities on the clinical outcome of the newborns at TC Hillers Hospital, Maumere. An analytical cross sectional study was carried out in newborns which showed criteria associated with congenital malaria. A thick and thin blood smear confirmed by nested PCR was performed in both mothers and infants. The association of congenital malaria with the newborn's health status was then assessed. From 112 mother-infant pairs included in this study, 92 were evaluated further. Thirty-nine infants (42.4%) were found to be infected and half of them were asymptomatic. Infected newborns had a 4.7 times higher risk in developing anemia compared to uninfected newborns (95% CI, 1.3-17.1). The hemoglobin level, erythrocyte amount, and hematocrit level were affected by the infants' parasite densities (P<0.05). Focusing on newborns at risk of congenital malaria, the prevalence is almost 3 times higher than in an unselected collective. Low birth weight, anemia, and pre-term birth were the most common features. Anemia seems to be significantly influenced by infant parasite densities but not by maternal parasitemia.