Improving Ethiopian Smallholders’ Income and Food Security: An Assessment of Alternative Policy Options

Smallholder farmers dominate food production, but also represent the largest share of people in developing countries experiencing food insecurity. In Ethiopia, agricultural growth now forms the backbone of the country’s long-term plans for economic growth. This study aims to analyze long-term changes to the agricultural sector and its consequences for the evolution of smallholder farmers under various policy scenarios. A farming typology based on the agro-ecological zone, the dominant activities, and the degree of market integration is established for this purpose. The agro-ecological zone is divided into the rainfall-sufficient and drought prone highland areas and the pastoralist lowlands. Dominant activities are either pure livestock-keeping or a combination of crops and livestock. Market integration is based on the share of agricultural output sold to the market. The resulting typology is extrapolated to all regions of Ethiopia. The spatially differentiated typology is integrated in an Ethiopia-version of Global Biosphere Management Model (GLOBIOM), a globally-consistent partial equilibrium model representing spatial land-use patterns and accounting for biophysical resource constraints. 19 crops (the standard GLOBIOM crops, teff, coffee and sesame), 4 animal types (cattle, sheep, goats and poultry) and 2 livestock products (milk and meat) are represented in the model. Projections of population and GDP growth per region are used to set up the initial demand for each product and each time step. Policies aiming to improve food security and reduce poverty are subsequently implemented. These include infrastructure and irrigation extensions as well as the improvement of access to fertilizers. Results show that the distribution of the farming systems changes across space and time under different policy scenarios. Impacts on smallholders’ poverty and food security status differ depending on the policy, enabling a spatially explicit assessment of policy options at both the local and national level

Surface excitonic emission and quenching effects in ZnO nanowire/nanowall systems: limiting effects on device potential.

We report ZnO nanowire/nanowall growth using a two-step vapour phase transport method on a-plane sapphire. X-ray diffraction and scanning electron microscopy data establish that the nanostructures are vertically well-aligned with c-axis normal to the substrate, and have a very low rocking curve width. Photoluminescence data at low temperatures demonstrate the exceptionally high optical quality of these structures, with intense emission and narrow bound exciton linewidths. We observe a high energy excitonic emission at low temperatures close to the band-edge which we assign to the surface exciton in ZnO at ~ 3.366 eV, the first time this feature has been reported in ZnO nanorod systems. This assignment is consistent with the large surface to volume ratio of the nanowire systems and indicates that this large ratio has a significant effect on the luminescence even at low temperatures. The band-edge intensity decays rapidly with increasing temperature compared to bulk single crystal material, indicating a strong temperature-activated non-radiative mechanism peculiar to the nanostructures. No evidence is seen of the free exciton emission due to exciton delocalisation in the nanostructures with increased temperature, unlike the behaviour in bulk material. The use of such nanostructures in room temperature optoelectronic devices appears to be dependent on the control or elimination of such surface effects

Photoionization of the Ne-like Si4+ ion in ground and metastable states in the 110–184-eV photon energy range

We present measurements of the absolute photoionization cross section of the neonlike Si4+ ion over the 110–184 eV photon energy range. The measurements were performed using two independent merged-beam setups at the super-ACO and ASTRID synchrotron-radiation facilities, respectively. Signals produced in the photoionization of the 2p subshell of the Si4+ ion both from the 2p6 1S0 ground state and the 2p53s 3P0,2 metastable levels were observed. Calculations of the 2p photoionization cross sections were carried out using a multi-configuration Dirac-Fock code. They give results in good agreement with the measured spectra. Comparison with other available theoretical results is also presented

Advanced Stochastic Optimization Modeling of the Water-energy-food Nexus for Robust Energy and Agricultural Development: Coal Mining Industry in Shanxi province, China

In this presentation, we discuss a modeling framework able to carry out an integrated systems analysis of interdependent energy-food-water-environmental systems while accounting for the competition to those systems posed by restricted natural resources under inherent uncertainties and systemic risks. The case study focuses on developments of coal industry in water-scarce regions of China. Coal is the main energy source in China responsible for country’s energy security. However, coal-based industries consume large quantities of water, which exacerbates the problem of water scarcity. The model accounts for water consumption by various coal mining, processing, and conversion technologies, as well as water and land requirements by different crops and management systems. Uncertain water supply and demand require robust solutions that would ensure demand-production balances and other (environmental, social) constraints in all scenarios. The model derives robust interdependent strategic and adaptive decisions using the “public-private partnership” principle. Strategic long-term decisions comprise the choice of coal-related technologies, land allocation, crop portfolio, and management technologies, while adaptive decisions concern trade and water management. Systemic risks and energy-food-water security considerations are characterized by quantile-based indicators arising due to systemic interdependencies among the systems and decisions of various stakeholders and potential adversaries. Robust solutions provide insights into how to develop and coordinate, in a sustainable way, the complex linkages and trade-offs, at spatial and temporal scales, between energy, agriculture, and water sectors, as well as how to manage potential systemic risks inherent to them. The model explores new coherent energy-food-water-environmental policies accounting for local-global interdependencies induced by national-international trade, as well as self-sufficient local solutions

Control of ZnO nanowire arrays by nanosphere lithography (NSL) on laser-produced ZnO substrates

Abstract Nanosphere lithography (NSL) is a successful technique for fabricating highlyordered arrays of ZnO nanowires typically on sapphire and GaN substrates. In this work, we investigate the use of thin ZnO films deposited on Si by pulsed laser deposition (PLD) as the substrate. This has a number of advantages over the alternatives above, including cost and potential scalability of production and it removes any issue of inadvertent n-type doping of nanowires by diffusion from the substrate. We demonstrate ordered arrays of ZnO nanowires, on ZnO-coated substrates by PLD, using a conventional NSL technique with gold as the catalyst. The nanowires were produced by Vapor Phase Transport (VPT) growth in a tube furnace system and grew only on the areas pre-patterned by Au. We have also investigated the growth of ZnO nanowires using ZnO catalyst points deposited by PLD through an NSL mask on a bare silicon substrate

Effect of polycrystallinity on the optical properties of highly oriented ZnO grown by pulsed laser deposition

We report the results of photoluminescence and reflectance measurements on highly c-axis oriented polycrystalline ZnO grown by pulsed laser deposition. The samples measured were grown under identical conditions and were annealed in-situ at various temperatures for 10-15 min. The band-edge photoluminescence spectra of the material altered considerably with an increase in grain size, with increased free exciton emission and observable excitonic structure in the reflectance spectra. The green band emission also increased with increasing grain size. A deformation potential analysis of the effect of strain on the exciton energy positions of the A- and B-excitons demonstrated that the experimental exciton energies could not be explained solely in terms of sample strain. We propose that electric fields in the samples due to charge trapping at grain boundaries are responsible for the additional perturbation of the excitons. This interpretation is supported by theoretical estimates of the exciton energy perturbation due to electric fields. The behaviour of the green band in the samples provides additional evidence in favour of our model

Control of ZnO nanowire arrays by nanosphere lithography (NSL) on laser-produced ZnO substrates

Nanosphere lithography (NSL) is a successful technique for fabricating highly ordered arrays of ZnO nanowires typically on sapphire and GaN substrates. In this work, we investigate the use of thin ZnO films deposited on Si by pulsed laser deposition (PLD) as the substrate. This has a number of advantages over the alternatives above, including cost and potential scalability of production and it removes any issue of inadvertent n-type doping of nanowires by diffusion from the substrate. We demonstrate ordered arrays of ZnO nanowires, on ZnO-coated substrates by PLD, using a conventional NSL technique with gold as the catalyst. The nanowires were produced by Vapor Phase Transport (VPT) growth in a tube furnace system and grew only on the areas pre-patterned by Au. We have also investigated the growth of ZnO nanowires using ZnO catalyst points deposited by PLD through an NSL mask on a bare silicon substrate

Climate change induced transformations of agricultural systems: insights from a global model

Climate change might impact crop yields considerably and anticipated transformations of agricultural systems are needed in the coming decades to sustain affordable food provision. However, decision-making on transformational shifts in agricultural systems is plagued by uncertainties concerning the nature and geography of climate change, its impacts, and adequate responses. Locking agricultural systems into inadequate transformations costly to adjust is a significant risk and this acts as an incentive to delay action. It is crucial to gain insight into how much transformation is required from agricultural systems, how robust such strategies are, and how we can defuse the associated challenge for decision-making. While implementing a definition related to large changes in resource use into a global impact assessment modelling framework, we find transformational adaptations to be required of agricultural systems in most regions by 2050s in order to cope with climate change. However, these transformations widely differ across climate change scenarios: uncertainties in large-scale development of irrigation span in all continents from 2030s on, and affect two-thirds of regions by 2050s. Meanwhile, significant but uncertain reduction of major agricultural areas affects the Northern Hemisphere's temperate latitudes, while increases to non-agricultural zones could be large but uncertain in one-third of regions. To help reducing the associated challenge for decision-making, we propose a methodology exploring which, when, where and why transformations could be required and uncertain, by means of scenario analysis

Field emission in ordered arrays of ZnO nanowires prepared by nanosphere lithography and extended Fowler-Nordheim analyses

A multistage chemical method based on nanosphere lithography was used to produce hexagonally patterned arrays of ZnO vertical nanowires, with 1 lm interspacing and aspect ratio 20, with a view to study the effects of emitter uniformity on the current emitted upon application of a dc voltage across a 250 lm vacuum gap. A new treatment, based on the use of analytical expressions for the image-potential correction functions, was applied to the linear region below 2000 V of the Fowler-Nordheim (FN) plot and showed the most suitable value of the work function / in the range 3.3–4.5 eV (conduction band emission) with a Schottky lowering parameter y ~ 0.72 and a field enhancement factor c in the 700–1100 range. A modeled c value of 200 was calculated for an emitter shape of a prolate ellipsoid of revolution and also including the effect of nanowire screening, in fair agreement with the experimental value. The Fowler-Nordheim current densities and effective emission areas were derived as 1011 Am2 and 1017 m2, respectively, showing that field emission likely takes place in an area of atomic dimensions at the tip of the emitter. Possible causes for the observed departure from linear FN plot behavior above 2000 V were discussed

3p photoabsorption spectra of Mn2+ and Mn3+

Time resolved EUV photoabsorption spectra of a manganese plasma have been recorded using the dual laser plasma technique. The 43 - 73 eV photon energy range is dominated by the 3p-3d giant resonance and to a lesser extent the 3p-4s resonances in both Mn2+ and Mn3+, recorded at an interplasma time delay of 80 ns and 30 ns respectively. These experimentally observed resonances are well reproduced by synthetic spectra calculated using the Hartree-Fock method. The synthetic spectra allow for absorption from excited states of the Mn2+ and Mn3+ ions