Securing Water, Sustaining Growth: Report of the GWP/OECD Task Force on Water Security and Sustainable Growth

Peer Revie

Signatures of exciton coupling in paired nanoemitters

An exciton formed by the delocalized electronic excitation of paired nanoemitters is interpreted in terms of the electromagnetic emission of the pair and their mutual coupling with a photodetector. A formulation directly tailored for fluorescence detection is identified, giving results which are strongly dependent on geometry and selection rules. Signature symmetric and antisymmetric combinations are analyzed and their distinctive features identified

Climate and southern Africa's water-energy-food nexus

In southern Africa, the connections between climate and the water-energy-food nexus are strong. Physical and socioeconomic exposure to climate is high in many areas and in crucial economic sectors. Spatial interdependence is also high, driven for example, by the regional extent of many climate anomalies and river basins and aquifers that span national boundaries. There is now strong evidence of the effects of individual climate anomalies, but associations between national rainfall and Gross Domestic Product and crop production remain relatively weak. The majority of climate models project decreases in annual precipitation for southern Africa, typically by as much as 20% by the 2080s. Impact models suggest these changes would propagate into reduced water availability and crop yields. Recognition of spatial and sectoral interdependencies should inform policies, institutions and investments for enhancing water, energy and food security. Three key political and economic instruments could be strengthened for this purpose; the Southern African Development Community, the Southern African Power Pool, and trade of agricultural products amounting to significant transfers of embedded water

Silicon Mie Resonators for Highly Directional Light Emission from monolayer MoS2

Controlling light emission from quantum emitters has important applications ranging from solid-state lighting and displays to nanoscale single-photon sources. Optical antennas have emerged as promising tools to achieve such control right at the location of the emitter, without the need for bulky, external optics. Semiconductor nanoantennas are particularly practical for this purpose because simple geometries, such as wires and spheres, support multiple, degenerate optical resonances. Here, we start by modifying Mie scattering theory developed for plane wave illumination to describe scattering of dipole emission. We then use this theory and experiments to demonstrate several pathways to achieve control over the directionality, polarization state, and spectral emission that rely on a coherent coupling of an emitting dipole to optical resonances of a Si nanowire. A forward-to-backward ratio of 20 was demonstrated for the electric dipole emission at 680 nm from a monolayer MoS2 by optically coupling it to a Si nanowire

How Market-Based Water Allocation Can Improve Water Use Efficiency in the Aral Sea Basin?

Increasing water demand due to population growth, irrigation expansion, industrial development, and the need for ecosystem improvements under mounting investment costs for developing new water sources calls for the efficient, equitable and sustainable management of water resources. This is particularly essential in the Aral Sea Basin (ASB) where ineffective institutions are the primary reason of intersectoral and inter-state water sharing conflicts and lack of sufficient investments for improving water use efficiency. This study examined market-based water allocation as an alternative option to the traditional administrative allocation to deal with water scarcity issues in the ASB. Potential economic gains of tradable water use rights were analyzed based on a newly constructed integrated hydro-economic river basin management model. The analysis differentiates between inter- catchment and intra-catchment water trading. The former does not consider any restrictions on water trading whereas the latter is based on the assumption that water trading is more likely to happen between neighboring water users located within the same catchment area. The analyses show that compared to fixed water allocation, inter-catchment water trading can improve basin-wide benefits by US$373 and US$ 476 million depending on water availability. Similarly, additional gains of US$259 to US$ 339 million are estimated under intra-catchment water trading depending on relative water availability. Trading gains are higher under drier conditions. However, water trading carries a series of transaction costs. We find that transaction costs exceeding US$0.05 per m3 of water traded wipe out the economic potential for water trading. Enforcement of the rule of law, infrastructural improvements, participation of representatives of all water stakeholders in decision making processes, and friendly relationships among the riparian countries are suggested as means for reducing transaction costs of water trading contracts

Market analysis for cultured proteins in low- and lower-middle income countries.

The global burden of malnutrition is unacceptably high.10 Worldwide, an estimated 22% of children under the age of five were stunted and 8% were wasted in 2018.11 Low-quality diets lacking in essential vitamins, minerals, proteins, and other nutrients are a key contributor to this burden.12 Animal-source foods—such as meat, poultry, fish, eggs, and dairy—are important components of a diverse diet and provide high-quality proteins and other essential nutrients that promote optimal growth and development.13,14,15,16,17As populations and incomes grow, the global demand for animal-source foods is projected to increase substantially, particularly in many low- and lower-middle income countries (LMICs).18,19 However, cost is currently a significant barrier to animal-source food consumption. In addition, meeting this growing demand for animal-source foods will require rapid increases in livestock production, which has significant environmental impacts, requiring considerable land, water, chemical, and energy inputs.10,17,18 Global food production is responsible for roughly one-quarter of all greenhouse gas emissions, most of which (up to 80%) are related to livestock.20,21 Livestock production is also a contributor to water pollution, deforestation, land degradation, overfishing, and antimicrobial resistance.20,22,23 Given these challenges, this report aims to assess the market for potentially more sustainable alternative proteins and their potential for use in LMIC settings. The report focuses on proteins derived from fermentation-based cellular agriculture, called cultured proteins, given their potential near-term time to market and their potential impact in LMIC populations. Most cultured protein manufacturers are developing proteins that are present in animal-source milk and eggs