Farming systems prevalent in sub-Saharan Africa are exposed and vulnerable to climate change due to their high dependence on rainfall. However, most studies have only estimated the impacts of climate change on agricultural productivity at a regional or national level. We add to this literature by focussing on the sub-national impacts. This study uses 30 years (1981–2011) of yield and weather data in Zambia and applies the Just and Pope model to determine how rainfall and temperature affect yield and yield variability of maize and beans at the national and subnational levels. Results show a negative impact of temperature rise on yield and a positive impact of rainfall rise on yield, above the current mean levels. These results differ by agro-ecological region. Worst-case-scenario predicted impacts using HadGEM-ES2 global circulation model show that major yield decreases (25% for maize and 34% for beans) by 2050 will be in region II and will be driven mainly by temperature increase offsetting the positive gains from rainfall increase. The model mainly under-predicts yield for maize and overpredicts yield for beans. These findings call for agro-ecological region-specific adaptation strategies and well-planned policy interventions to make agriculture more resilient to climate change.

The membrane dipole potential that arises from the interfacial water and constitutive dipolar groups of lipid molecules modulates the interaction of amphiphiles and proteins with membranes. Consequently, its determination for lipid mixtures resembling the existing diversity in biological membranes is very relevant. In this work the dipole potential of monolayers, formed at the air-water interface, from pure or mixed lipids (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), 1-palmitoyl-2-ol0eoyl-sn-glycero-3-phosphatidyserine (POPS), Sphingomyelin (SpM) and cholesterol) were measured and correlated with the mean area per lipid. The results showed that, as previously observed, cholesterol increases the dipole potential in correspondence with the decrease in the average area per lipid and that the replacement of phosphocholine lipids by sphingomyelin leads to a decrease in the dipole potential. We have also observed that 20 mol% of POPE induces a monolayer condensation which is not affecting the measured dipole potential, except when cholesterol is added to the mixture. Additionally, at the small mole fractions encountered in biomembranes, the presence of the negatively charged lipid POPS increases the dipole potential of monolayers even though an enhancement in the monolayer packing is not evident. This increase in the dipole potential due to POPS and cholesterol and the smaller dipole potential of monolayers containing large amounts of SpM generates a non-zero transbilayer dipole potential in the asymmetric plasma membrane of eukaryotic cells.