Fabry-Perot -like resonant transmission of microwave radiation through a single subwavelength slit in a thick aluminum plate is quantified for a range of slit widths. Surprisingly, and in contrast to previous studies [e.g., Y. Takakura, Phys. Rev. Lett. 86, 5601 (2001)], the resonant frequency exhibits a maximum as a function of slit width, decreasing as the slit width is reduced to less than 2% of the incident wavelength. This result accords with a new model based on coupled surface plasmon theory taking into account the finite conductivity, and hence permittivity, of the metal. This is contrary to a common assumption that metals can be treated as infinitely conducting in this regime.

Hibernation, the dead storage period when a mobile phone is still retained by the user at its end-of-life, is both a common and a significant barrier to the effective flow of time-sensitive stock value within a circular economic model. In this paper we present the findings of a survey of 181 mobile phone owners, aged between 18-25years old, living and studying in the UK, which explored mobile phone ownership, reasons for hibernation, and replacement motives. This paper also outlines and implements a novel mechanism for quantifying the mean hibernation period based on the survey findings. The results show that only 33.70% of previously owned mobile phones were returned back into the system. The average duration of ownership of mobile phones kept and still in hibernation was 4years 11months, with average use and hibernation durations of 1year 11months, and 3years respectively; on average, mobile phones that are kept by the user are hibernated for longer than they are ever actually used as primary devices. The results also indicate that mobile phone replacement is driven primarily by physical (technological, functional and absolute) obsolescence, with economic obsolescence, partly in response to the notion of being 'due an upgrade', also featuring significantly. We also identify in this paper the concept of a secondary phone, a recently replaced phone that holds a different function for the user than their primary phone but is still valued and intentionally retained by the user, and which, we conclude, should be accounted for in any reverse logistics strategy.

Purpose The aim of this study is to explore the literature surrounding the environmental impact of mobile phones and the implications of moving from the current business model of selling, using and discarding phones to a product service system based upon a cloud service. The exploration of the impacts relating to this shift and subsequent change in scope is explored in relation to the life cycle profile of a typical smartphone. Methods A literature study is conducted into the existing literature in order to define the characteristics of a Btypicalŝ martphone. Focus is given to greenhouse gas (GHG) emissions in different life cycle phases in line with that reported in the majority of literature. Usage patterns from literature are presented in order to show how a smartphone is increasingly responsible for not only data consumption but also data generation. The subsequent consequences of this for the balance of the life cycle phases are explored with the inclusion of wider elements in the potential expanded mobile infrastructure, such as servers and the network. Results and discussion From the available literature, the manufacturing phase is shown to dominate the life cycle of a Btypical^smartphone for GHG emissions. Smartphone users are shown to be increasingly reliant upon the internet for provision of their communications. Adding a server into the scope of a smartphone is shown to increase the use phase impact from 8.5 to 18.0 kg CO 2 -eq, other phases are less affected. Addition of the network increases the use phase by another 24.7 kg CO 2 -eq. In addition, it is shown that take-back of mobile phones is not effective at present and that prompt return of the phones could result in reduction in impact by best reuse potential and further reduction in toxic emissions through inappropriate disposal. Conclusions The way in which consumers interact with their phones is changing, leading to a system which is far more integrated with the internet. A product service system based upon a cloud service highlights the need for improved energy efficiency to make greatest reduction in GHG emissions in the use phase, and gives a mechanism to exploit residual value of the handsets by timely return of the phones, their components and recovery of materials.

Abstract:The Planetary Boundaries (PB) framework represents a significant advance in specifying the ecological constraints on human development. However, to enable decision-makers in business and public policy to respect these constraints in strategic planning, the PB framework needs to be developed to generate practical tools. With this objective in mind, we analyse the recent literature and highlight three major scientific and technical challenges in operationalizing the PB approach in decision-making: first, identification of thresholds or boundaries with associated metrics for different geographical scales; second, the need to frame approaches to allocate fair shares in the 'safe operating space' bounded by the PBs across the value chain and; third, the need for international bodies to co-ordinate the implementation of the measures needed to respect the Planetary Boundaries. For the first two of these challenges, we consider how they might be addressed for four PBs: climate change, freshwater use, biosphere integrity and chemical pollution and other novel entities. Four key opportunities are identified: (1) development of a common system of metrics that can be applied consistently at and across different scales; (2) setting 'distance from boundary' measures that can be applied at different scales; (3) development of global, preferably open-source, databases and models; and (4) advancing understanding of the interactions between the different PBs. Addressing the scientific and technical challenges in operationalizing the planetary boundaries needs be complemented with progress in addressing the equity and ethical issues in allocating the safe operating space between companies and sectors.

The water–energy–food (WEF) nexus has become a popular, and potentially powerful, frame through which to analyse interactions and interdependencies between these three systems. Though the case for transdisciplinary research in this space has been made, the extent of stakeholder engagement in research remains limited with stakeholders most commonly incorporated in research as end-users. Yet, stakeholders interact with nexus issues in a variety of ways, consequently there is much that collaboration might offer to develop nexus research and enhance its application. This paper outlines four aspects of nexus research and considers the value and potential challenges for transdisciplinary research in each. We focus on assessing and visualising nexus systems; understanding governance and capacity building; the importance of scale; and the implications of future change. The paper then proceeds to describe a novel mixed-method study that deeply integrates stakeholder knowledge with insights from multiple disciplines. We argue that mixed-method research designs—in this case orientated around a number of cases studies—are best suited to understanding and addressing real-world nexus challenges, with their inevitable complex, non-linear system characteristics. Moreover, integrating multiple forms of knowledge in the manner described in this paper enables research to assess the potential for, and processes of, scaling-up innovations in the nexus space, to contribute insights to policy and decision making.

Purpose Rearing crickets in the UK for the live pet food market is already a well-established industry. However, there is interest in also producing food for human consumption. This paper presents a life cycle assessment (LCA) of a current live pet food business. Using results from this LCA, the papers explores how current business practices could be improved to reduce environmental impacts, and discusses the potential benefits of a hybrid live pet food/human consumption business model. Methods An attributional, cradle-to-farm-gate life cycle assessment was conducted on rearing crickets for the live pet food market, with data collected on-site at a case study business. Results are reported in multiple impact categories from the ILCD 2011 Midpoint+ method. Comparison is made to the only other similar study: an LCA of rearing crickets in Thailand for human consumption (Halloran et al. J Clean Prod 156:83-94, 2017). The sources of the different environmental impacts between the two studies are explored and inefficiencies in the live pet food rearing process identified. Subsequently, scenarios are used to explore how the inefficiencies may be mitigated, and environmental impact of the live pet food production process reduced through adoption of a hybrid live pet food/human food production model. Results and discussions The environmental impact was found to be larger across all impact categories than the only known comparable study, which is for rearing crickets in Thailand for human consumption (Halloran et al. J Clean Prod 156:83-94, 2017). Some of this difference is due to the heating required for rearing crickets in a climate such as the UK, and some is due to the requirements of the live pet food market being much more demanding on resources than the human food model. The current study identifies improvements in practices that would make this contrast less stark, such as optimizing feeding practices, and the benefits of moving to a hybrid live pet food/human consumption business model. Conclusions This is the first LCA of crickets reared in the UK. The results highlight inefficiencies in the rearing process that are now being addressed by the case study business. The study also shows the potential co-benefits of a hybrid business model, in which crickets for human consumption are produced alongside crickets for the live pet food market.

Grand societal challenges such as climate change, poverty and biodiversity loss call for rapid and radical changes to systems of production and consumption. Consequently, there is a growing interest in the dynamics of innovation, both social and technical, to accelerate innovation diffusion so as to increase the possibility of a step‐change or large‐scale transition. Research on the water–energy–food nexus adds an additional dimension to existing discussions, calling for transitions that recognise the sustainability challenges facing three major resource domains, and the synergies and tensions involved in their management. This paper examines anaerobic digestion (AD) – an example of innovation with potential benefits across the water–energy–food nexus – to understand the conditions that influence the rate of AD implementation and the achievement of its potential multi‐sectoral benefits across the water–energy–food nexus. Interview data regarding 15 AD plants are examined alongside complementary data from interviews and workshops using the Technological Innovation Systems framework. This framework provides an analytical structure through which the processes that enable and constrain the implementation of AD in the UK can be examined, enabling the identification of potential mechanisms to support AD's wider and more effective deployment. The findings call for recognition of the unintended consequences of sectoral support mechanisms for technological adaptation, and consequent performance of AD in other resource domains and call for greater integration between policy mechanisms to enable AD to perform across the nexus. They also highlight a need to assimilate knowledge from multiple sources (including site‐specific understanding gained from experimentation) to enhance the base on which policy and decision‐making occurs. These findings contribute to existing literature on sustainable transitions by examining the complexities of multi‐sectoral resource management in the context of nexus research.

Mobile phones offer many potential social benefits throughout their lifetime, but this life is often much shorter than design intent. Reuse of the phone in a developing country allows these social benefits to be fully realized. Unfortunately, under the current state of development of recycling infrastructure, recovery rates of phones after reuse are very low in those markets, which may lead to an environmental burden due to loss of materials to landfill. In order to recover those materials most effectively, recycling in developed countries may be the best option, but at a cost of the ability to reuse the phones. The issues facing integration of social and environmental concerns into a single life cycle assessment and resulting challenges of identifying the disposal option with the most sustainable outcome are explored using mobile phones as a case study. These include obtaining sufficient geographical and temporal detail of the end of life options, the collation and analysis of the large amounts of data generated and the weighting of the disparate environmental and social impact categories. The numerous challenges may mount up to make performing life cycle assessment of mobile phones unwieldy. Instead of trying to encompass every aspect in full, it is proposed that focus is given to answering a question which takes into account the resources available: it is important to ask the question which has the best chance of being answered