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Background:Few studies have examined the long-term, cross-national, and population-level impacts of exclusive breastfeeding on major global child health indicators. We investigated the overall and independent associations between exclusive breastfeeding and under-five mortality in 57 low- and-middle-income countries.Methods:Data were obtained from the latest World Health Organization, United Nations, and United Nations Children’s Fund databases for 57 low- and middle-income countries covering the periods 2006-2014. Multivariate linear regression was used to estimate the effects of exclusive breastfeeding on under-five mortality after adjusting for differences in socioeconomic, demographic, and health-related factors.Results:In multivariate models, exclusive breastfeeding was independently associated with under-five mortality after adjusting for sociodemographic and health systems-related factors. A 10 percentage-points increase in exclusive breastfeeding was associated with a reduction of 5 child deaths per 1,000 live births. A one-unit increase in Human Development Index was associated with a decrease of 231 under-five child deaths per 1,000 live births. A $100 increase in per capita health care expenditure was associated with a decrease of 2 child deaths per 1,000 live births. One unit increase in physician density was associated with 2.8 units decrease in the under-five mortality rate.Conclusions and Global Health Implications:Population-level health system and socioeconomic factors exert considerable effect on the association between exclusive breastfeeding and under-five mortality. Given that the health policy and socioeconomic indicators shown to influence exclusive breastfeeding and under-five mortality are modifiable, policy makers could potentially target specific policies and programs to address national-level deficiencies in these sectors to reduce under-five mortality in their countries.

The processes associated with the deformation and fracture of polystyrene tested in uniaxial tension have been studied over a range of strain rates from 1.4 × 10−2 to 4.3 × 10−7 sec−1 and at constant stresses between 4.1 and 2.9 kg/mm2. The effect of strain rate on the surface craze distribution prior to fracture, the fracture stress, the mechanism of nucleation of cracks, and the nature of fracture surfaces associated with slow and fast crack propagation have been determined. The changes in fracture surface appearance have been studied using optical and stereoscan microscopy. The observations are consistent with the model presented in a previous paper. Fracture is preceded by craze formation, cavitation in the craze, coalescence of cavities to form large planar cavities which propagate slowly until a critical stage is reached at which fast crack propagation occurs. The effect of changes of strain rate and material variables on these processes is discussed.

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