502 research outputs found
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Assessing the potential economic benefits to farmers from various GM crops becoming available in the European Union by 2025: results from an expert survey
This paper reports on a study that identified a range of crop-trait combinations that are: agronomically suited to the EU; provide advantages to arable farmers and consumers; and are either already available in international markets, or advancing along the development pipeline and likely to become available by 2025. An expert stakeholder panel was recruited and asked for their views, using the Delphi approach, on the impact of these crop-traits on enterprise competitiveness, through changes to yields, production costs and product prices. In terms of input traits, there was consensus that traits such as herbicide tolerant/insect resistant (HT/IR) maize, HT sugar beet and HT soya bean would provide positive benefits for farmers. Output-side traits such as winter-sown rape with reduced saturated fats, were seen as offering benefits to consumers, but were either likely to be restricted to niche markets, or offer relatively modest price premia to farmers growing them. Our analysis of the financial impact of the adoption of GM crops more widely in the EU, showed that the competitiveness of the agricultural sector could well be improved by this. However, such improvements would be relatively small-scale in that large-scale national natural advantages from either economic or environmental conditions is unlikely to be overturned
Detecting Delamination via Nonlinear Wave Scattering in a Bonded Elastic Bar
In this paper we examine the effect of delamination on wave scattering, with
the aim of creating a control measure for layered waveguides of various bonding
types. Previous works have considered specific widths of solitary waves for the
simulations, without analysing the effect of changing the soliton parameters.
We consider two multi-layered structures: one containing delamination
"sandwiched" by perfect bonding and one containing delamination but
"sandwiched" by soft bonding. These structures are modelled by coupled
Boussinesq-type equations. Matched asymptotic multiple-scale expansions lead to
coupled Ostrovsky equations in soft bonded regions and Korteweg-De Vries
equations in the perfectly bonded and delaminated region. We use the Inverse
Scattering Transform to predict the behaviour in the delaminated regions. In
both cases, numerical analysis shows that we can predict the delamination
length by changes in the wave structure, and that these changes depend upon the
Full Width at Half Magnitude (FWHM) of the incident soliton. In the case of
perfect bonding, we derive a theoretical prediction for the change and confirm
this numerically. For the soft bonding case, we numerically identify a similar
relationship using the change in amplitude. Therefore we only need to compute
one curve to determine the behaviour for any incident solitary wave, creating a
framework for designing measurement campaigns for rigorously testing the
integrity of layered structures.Comment: 12 pages, 7 figure
Phosphatase activity and organic phosphorus turnover on a high Arctic glacier
Arctic glacier surfaces harbour abundant microbial communities consisting mainly of heterotrophic and photoautotrophic bacteria. The microbes must cope with low concentrations of nutrients and with the fact that both the dissolved and debris-bound nutrient pools are dominated by organic phases. Here we provide evidence that phosphorus (P) is deficient in the supraglacial environment on a Svalbard glacier, we quantify the enzymatic activity of phosphatases in the system and we estimate the contribution of the microbes to the cycling of the dominant organic P in the supraglacial environment. Incubation of cryoconite debris revealed significant phosphatase activity in the samples (19–67 nmol MUP g<sup>&minus;1</sup> h<sup>&minus;1</sup>). It was inhibited by inorganic P during incubations and had its optimum at around 30&deg;C. The phosphatase activity measured at near-in situ temperature and substrate concentration suggests that the available dissolved organic P can be turned over by microbes within ~3–11 h on the glacier surface. By contrast, the amount of potentially bioavailable debris-bound organic P is sufficient for a whole ablation season. However, it is apparent that some of this potentially bioavailable debris-bound P is not accessible to the microbes
Recommended from our members
Identifying GM crops for future cultivation in the EU through a Delphi forecasting exercise
This paper reports on a Delphi forecasting exercise carried out to identify crop traits that could feasibly be introduced to the advantage of arable farmers, and for the general benefit of the public, in EU member states. An expert stakeholder panel was recruited and asked for opinions on scenarios concerning the availability of GM events, and also scenarios that envisage novel crops developed using advanced technology not classified as GM. In a second round of consultation, panel members commented anonymously on opinions elicited in the first phase. Results indicate that crops with input traits most likely to become available in the EU before 2025 are HTIR maize, HT sugarbeet and HT soybean; these are already widely adopted outside Europe. The crops with output traits most likely to become available and offering benefits to consumers are winter-sown varieties of rape with reduced saturated fats, spring varieties of which are already available outside EU (notably Canadian Canola)
A comparison of the Bravyi-Kitaev and Jordan-Wigner transformations for the quantum simulation of quantum chemistry
The ability to perform classically intractable electronic structure
calculations is often cited as one of the principal applications of quantum
computing. A great deal of theoretical algorithmic development has been
performed in support of this goal. Most techniques require a scheme for mapping
electronic states and operations to states of and operations upon qubits. The
two most commonly used techniques for this are the Jordan-Wigner transformation
and the Bravyi-Kitaev transformation. However, comparisons of these schemes
have previously been limited to individual small molecules. In this paper we
discuss resource implications for the use of the Bravyi-Kitaev mapping scheme,
specifically with regard to the number of quantum gates required for
simulation. We consider both small systems which may be simulatable on
near-future quantum devices, and systems sufficiently large for classical
simulation to be intractable. We use 86 molecular systems to demonstrate that
the use of the Bravyi-Kitaev transformation is typically at least approximately
as efficient as the canonical Jordan-Wigner transformation, and results in
substantially reduced gate count estimates when performing limited circuit
optimisations.Comment: 46 pages, 11 figure
Modelling and experimental investigation of Nb2O5 as a high-rate battery anode material
Modelling and understanding the battery electrochemical performance at high rates is a great challenge. Known for its fast rate and good cyclability, niobium pentoxide (Nb2O5) is a promising anode material for lithium-ion batteries and is specifically modelled and investigated in this work. Commercially sourced Nb2O5 was characterised using scanning electron microscopy, X-ray diffraction, and micro-computed tomography. The Nb2O5 material was found to contain large rod- and ball-like polycrystalline particles of tens of microns in size and have mixed T-Nb2O5 and H-Nb2O5 phases. The electrochemical performance of the material after ball milling was tested via cyclic voltammetry and constant-current cycling at different C-rates up to 50C (10,000 mA g−1). The material achieved a similar charge capacity (143 mAh g−1) to T-Nb2O5 at 0.5C and this capacity could be retained by more than 55% when C-rate was increased to 10C. The experimental results were used to support the development of the Doyle-Fuller-Newman electrochemical model for Nb2O5. By model parameterization, the reference exchange-current density and solid-state diffusivity of the present Nb2O5 were estimated to be 9.6 × 10−4 A m−2 and 6.2 × 10−14 m2 s−1, respectively. The model achieved accurate prediction of the battery performance up to currents of 5C with the obtained constant properties. However, the properties of Nb2O5 were found to be rate-dependent at higher C-rates when good agreements between the model and experiment were maintained. The decrease of the two properties at 10−50C revealed that there was a change of dominant charge storage mechanism from diffusion-controlled lithium insertion to capacitive effects, which was experimentally observed in the cyclic voltammetry
Recent advances in acoustic diagnostics for electrochemical power systems
Over the last decade, acoustic methods, such as acoustic emission and ultrasonic testing, have been increasingly deployed for process diagnostics and health monitoring of electrochemical power devices including batteries, fuel cells, and water electrolysers. These acoustic are non-invasive, highly sensitive, and low cost, while also providing a high level of spatial and temporal resolution, and practicality. The application of these tools in electrochemical devices is based on identifying changes in acoustic signals due to physical, structural, and electrochemical properties change within the material which are then correlated to critical processes and the health status of the devices. This review discusses recent progress in the use of acoustic methods for process and health-monitoring of major electrochemical energy conversion and storage devices. First, the fundamental concepts and principles of acoustic emission and ultrasonic testing are introduced, followed by a discussion of the range of electrochemical energy conversion and storage systems, and how acoustic techniques are being used to study relevant materials and devices. Conclusions and future perspectives highlighting some of the unique challenges and potential commercial and academic applications of the devices are also discussed. It is expected that, with further developments, acoustic techniques will form a key part of the suite of diagnostic techniques routinely used to monitor electrochemical devices across various processes including fabrication, on-board maintenance, post-mortem examination and second life or recycle decision support to aid the deployment of these devices in increasingly demanding applications
Sustainability in Turbulent Times: Lessons from the Nexus Network for supporting transdisciplinary research
This is the final version. Available from the Nexus Network via the link in this recordEconomic and Social Research Council (ESRC
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