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Food provides energy and nutrients, but its acquisition requires energy expenditure. In post-hunter-gatherer societies, extra-somatic energy has greatly expanded and intensified the catching, gathering, and production of food. Modern relations between energy, food, and health are very complex, raising serious, high-level policy challenges. Together with persistent widespread under-nutrition, over-nutrition (and sedentarism) is causing obesity and associated serious health consequences. Worldwide, agricultural activity, especially livestock production, accounts for about a fifth of total greenhouse-gas emissions, thus contributing to climate change and its adverse health consequences, including the threat to food yields in many regions. Particular policy attention should be paid to the health risks posed by the rapid worldwide growth in meat consumption, both by exacerbating climate change and by directly contributing to certain diseases. To prevent increased greenhouse-gas emissions from this production sector, both the average worldwide consumption level of animal products and the intensity of emissions from livestock production must be reduced. An international contraction and convergence strategy offers a feasible route to such a goal. The current global average meat consumption is 100 g per person per day, with about a ten-fold variation between high-consuming and low-consuming populations. 90 g per day is proposed as a working global target, shared more evenly, with not more than 50 g per day coming from red meat from ruminants (ie, cattle, sheep, goats, and other digastric grazers).

Although Cs2AgBiBr6 halide elpasolites have gained substantial attention as potential nontoxic and stable alternatives to lead–halide perovskites, they are limited by their wide bandgaps >2.2 eV. Alloying with Sb into the pnictogen site has been shown to be an effective method to lower the bandgap, but this has not translated into improvements in photovoltaic (PV) performance. Herein, the underlying causes are investigated. Pinhole‐free films of Cs2Ag(SbxBi1−x)Br6 are achieved through antisolvent dripping, but PV devices still exhibit a reduction in power conversion efficiency from 0.44% ± 0.02% (without Sb) to 0.073% ± 0.007% (90% Sb; lowest bandgap). There is a 0.7 V reduction in the open‐circuit voltage, which correlates with the appearance of a sub‐bandgap state ≈0.7 eV below the optical bandgap in the Sb‐containing elpasolite films, as found in both absorbance and photoluminescence measurements. Through detailed Williamson–Hall analysis, it is found that adding Sb into the elpasolite films leads to an increase in film strain. This strain is relieved through aerosol‐assisted solvent treatment, which reduces both the sub‐bandgap state density and energetic disorder in the films, as well as reducing the fast early decay in the photogenerated carrier population due to trap filling. This work shows that Sb alloying leads to the introduction of extra sub‐bandgap states that limit the PV performance, but can be mitigated through post‐annealing treatment to reduce disorder and strain.

The drainage of a viscous gravity current into a deep porous medium driven by both the gravitational and capillary forces is considered in two steps. We first study the one-dimensional case where a layer of fluid drains vertically into an infinitely deep porous medium. We determine a transition from the capillary-driven regime to the gravity-driven regime as time proceeds. Second, we solve the coupled spreading and drainage problem. There are no self-similar solutions of the problem for the entire time period, so asymptotic analyses are developed for the height, depth and front location in both the early-time and the late-time periods. In addition, we present numerical results of the governing partial differential equations, which agree well with the self-similar solutions in the appropriate asymptotic limits.

The purpose of this paper is to provide a broad overview of the social and environmental costs and benefits of biofuels in Asia. The major factors that will determine the impacts of biofuels are: (1) their contribution to land-use change, (2) the feedstocks used, and (3) issues of technology and scale. Biofuels offer economic benefits, and in the right circumstances can reduce emissions and make a small contribution to energy security. Feedstocks that involve the conversion of agricultural land will affect food security and cause indirect land-use change, while those that replace forests, wetlands or natural grasslands will increase emissions and damage biodiversity. Biofuels from cellulose, algae or waste will avoid some of these problems, but come with their own set of uncertainties and risks. In order to ensure net societal benefits of biofuel production, governments, researchers, and companies will need to work together to carry out comprehensive assessments, map suitable and unsuitable areas, and define and apply standards relevant to the different circumstances of each country. The greatest benefits may come from feedstocks produced on a modest scale as co-products of smart technologies developed for phytoremediation, waste disposal and emissions reduction.

Climate change and an increased interest in renewable energy have resulted in a burgeoning wind energy sector. However, in the recent past, wind farms have faced resistance in acquiring permits due to concerns about their long-term effects on the local community. To understand the extent of these externalities, this study qualitatively meta-analyses four socio-economic impacts of interest, namely: house prices, tourism, catalytic effects of supply chain clustering, and social change. Geographically, the analysed reports include Europe, Canada and the US, and deductions are made for the EU. In order to bridge the gap of unavailability of primary data on the wind sector, relevant conclusions are drawn from other comparable sectors. Based on a rigorous review of primary qualitative research, this study concludes that offshore wind farms should be located more than 40 km away from the coast to eliminate risks of housing price devaluation and tourist activity reduction, which would directly affect the economic value of the region. In addition, the study found limited evidence to acknowledge the employment benefits in the local economy and social change in the community due to offshore wind farms. Monitoring mechanisms should be set up to prove or disprove the creation of local employment, crime and substance abuse. Furthermore, the study finds that adequate planning and management can ensure better socioeconomic outcomes in the community. Further research is recommended for the specific impact of overhead transmission lines and substations on property values and tourism.

The overwhelming majority of microelectromechanical piezoelectric vibration energy harvesting topologies have been based on cantilevers, doubly-clamped beams or basic membranes. While these conventional designs offer simplicity, their broadband response are thus far limited. This paper investigates the feasibility of a new integrated cantilever-on-membrane design that explores the optimisation of piezoelectric strain distribution and improvement of the broadband power output. While a classic membrane has the potential to offer a broader resonant peak than its cantilever counterpart, the inclusion of a centred proof mass compromises its otherwise high strain energy regions. The proposed topology addresses this issue by relocating the proof mass onto subsidiary cantilevers and combines the merits of both the membrane and the cantilever designs. Numerical simulations, constructed using fitted values based on finite element models, were used to investigate the broadband response of the proposed design in contrast to a classic plain membrane. Experimentally, when subjected to a band-limited white noise excitation, the new cantilevers-on-membrane harvester exhibited nearly two fold power output enhancement when compared to a classic plain membrane harvester of a comparable size.

AbstractSpecies’ vulnerability to extinction is strongly impacted by their geographical range size. Formulating effective conservation strategies therefore requires a better understanding of how the ranges of the world’s species have changed in the past, and how they will change under alternative future scenarios. Here, we use reconstructions of global land use and biomes since 1700, and 16 possible climatic and socio-economic scenarios until the year 2100, to map the habitat ranges of 16,919 mammal, bird, and amphibian species through time. We estimate that species have lost an average of 18% of their natural habitat range sizes thus far, and may lose up to 23% by 2100. Our data reveal that range losses have been increasing disproportionately in relation to the area of destroyed habitat, driven by a long-term increase of land use in tropical biodiversity hotspots. The outcomes of different future climate and land use trajectories for global habitat ranges vary drastically, providing important quantitative evidence for conservation planners and policy makers of the costs and benefits of alternative pathways for the future of global biodiversity.