476 research outputs found

    Determining the Neutrino Mass Hierarchy with Cosmology

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    The combination of current large scale structure and cosmic microwave background (CMB) anisotropies data can place strong constraints on the sum of the neutrino masses. Here we show that future cosmic shear experiments, in combination with CMB constraints, can provide the statistical accuracy required to answer questions about differences in the mass of individual neutrino species. Allowing for the possibility that masses are non-degenerate we combine Fisher matrix forecasts for a weak lensing survey like Euclid with those for the forthcoming Planck experiment. Under the assumption that neutrino mass splitting is described by a normal hierarchy we find that the combination Planck and Euclid will possibly reach enough sensitivity to put a constraint on the mass of a single species. Using a Bayesian evidence calculation we find that such future experiments could provide strong evidence for either a normal or an inverted neutrino hierachy. Finally we show that if a particular neutrino hierachy is assumed then this could bias cosmological parameter constraints, for example the dark energy equation of state parameter, by > 1\sigma, and the sum of masses by 2.3\sigma.Comment: 9 pages, 6 figures, 3 table

    Strengthening impact assessment: a call for integration and focus

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    We suggest that the impact assessment community has lost its way based on our observation that impact assessment is under attack because of a perceived lack of efficiency. Specifically, we contend that the proliferation of different impact assessment types creates separate silos of expertise and feeds arguments for not only a lack of efficiency but also a lack of effectiveness of the process through excessive specialisation and a lack of interdisciplinary practice. We propose that the solution is a return to the basics of impact assessment with a call for increased integration around the goal of sustainable development and focus through better scoping. We rehearse and rebut counter arguments covering silo-based expertise, advocacy, democracy, sustainability understanding and communication. We call on the impact assessment community to rise to the challenge of increasing integration and focus, and to engage in the debate about the means of strengthening impact assessment

    Characterising the collaboration between academia and practice in UK Environmental Assessment

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    The UK has been one of the countries at the vanguard of developments of Environmental Assessment (EA) theory and practice. It is likely that this globally prominent position has been developed through ongoing collaboration between academia and practice which pervades teaching, research, and practice itself. However, the scale and nature of the collaboration is unclear, which restricts learning that might lead to encouraging and growing existing collaborations, not just inside but also outside the UK; therefore, the aim of this paper is to fill this research gap by characterising the nature of the academia-practice collaboration in the UK. To achieve this aim, a typology of collaboration was developed through literature review and used as the basis for a survey of research and publication active UK-based academics to both, validate the typology, and determine the nature of their collaboration with practice. The results, whilst biased to the views of academics, indicate a considerable range of collaborative activities that benefit both academics and practitioners alike. The resulting typology of collaborative activities might conceivably act as a template for knowledge exchange between academia and practice in the EA field. This template can conceivably be applied as a set of criteria to plan better collaboration to the benefit of academics and practitioners alike

    Tetrabutylammonium cation expulsion versus perchlorate electrolyte anion uptake in the electrochemical oxidation of microcrystals of [(C4H9)4N][Cr(CO)5I] mechanically attached to a gold electrode: a voltammetric and quartz crystal microbalance study

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    The electrochemistry of microcrystals of [(C4H9)4N][Cr(CO)5I] attached to a gold electrode which is placed in aqueous (lithium or tetrabutylammonium perchlorate) electrolyte media has been studied in detail by chronoamperometric, voltammetric and electrochemical quartz crystal microbalance (ECQCM) techniques. Whilst chronoamperometric and voltammetric measurements show that the expected one-electron oxidation of microcrystalline [Cr(CO)5I]− solid to Cr(CO)5I occurs at the solid-electrode-solvent (electrolyte) interface, the ECQCM measurements reveal that charge neutralization does not occur exclusively via the expected ejection of the tetrabutylammonium cation. Rather, uptake of ClO4 − occurs under conditions where the solubility of sparingly soluble [(C4H9)4N]ClO4 is exceeded. This is the first time that uptake of an anion rather than loss of a cation has been detected in association with an oxidation during electrochemical studies of microcrystals attached to electrode surfaces. It is therefore now emerging that analogous charge neutralization processes to those encounted in voltammetric studies on conducting polymers are available in voltammetric studies of microcrystals attached to electrodes which are placed in contact with solvent (electrolyte) media. In the presence of LiClO4 as the electrolyte, an ion exchange process occurs leading to formation of Li[Cr(CO)5I] . X H2O which then slowly dissolves in water at a rate that is strongly influenced by the electrolyte concentration, the relatively hydrophobic nature of the [(C4H9)4N]+ cation and the poor solubility of [(C4H9)4N]ClO4

    Retuning the Catalytic Bias and Overpotential of a [NiFe]-Hydrogenase via a Single Amino Acid Exchange at the Electron Entry/Exit Site

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    The redox chemistry of the electron entry/exit site in Escherichia coli hydrogenase-1 is shown to play a vital role in tuning biocatalysis. Inspired by nature, we generate a HyaA-R193L variant to disrupt a proposed Arg-His cation-π interaction in the secondary coordination sphere of the outermost, "distal", iron-sulfur cluster. This rewires the enzyme, enhancing the relative rate of H 2 production and the thermodynamic efficiency of H 2 oxidation catalysis. On the basis of Fourier transformed alternating current voltammetry measurements, we relate these changes in catalysis to a shift in the distal [Fe 4S 4] 2+/1+ redox potential, a previously experimentally inaccessible parameter. Thus, metalloenzyme chemistry is shown to be tuned by the second coordination sphere of an electron transfer site distant from the catalytic center

    A criteria-driven approach to the CO2 storage site selection of East Mey for the acorn project in the North Sea

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    Carbon Capture and Storage (CCS) is an essential tool in the fight against climate change. Any prospective storage site must meet various criteria that ensure the effectiveness, safety and economic viability of the storage operations. Finding the most suitable site for the storage of the captured CO2 is an essential part of the CCS chain of activity. This work addresses the site selection of a second site for the Acorn CCS project, a project designed to develop a scalable, full-chain CCS project in the North Sea (offshore northeast Scotland). This secondary site has been designed to serve as a backup and upscaling option for the Acorn Site, and has to satisfy pivotal project requirements such as low cost and high storage potential. The methodology followed included the filtering of 113 input sites from the UK CO2Stored database, according to general and project-specific criteria in a multi-staged approach. This criteria-driven workflow allowed for an early filtering out of the less suitable sites, followed by a more comprehensive comparison and ranking of the 15 most suitable sites. A due diligence assessment was conducted of the top six shortlisted sites to produce detailed assessment of their storage properties and suitability, including new geological interpretation and capacity calculations for each site. With the new knowledge generated during this process, a critical comparison of the sites led to selection of East Mey as the most suitable site, due to its outstanding storage characteristics and long-lasting hydrocarbon-production history, that ensure excellent data availability to risk-assess storage structures. A workshop session was held to present methods and results to independent stakeholders; feedback informed the final selection criteria. This paper provides an example of a criteria-driven approach to site selection that can be applied elsewhere.Project ACT-Acorn is gratefully thanked for funding this study. ACT Acorn, project 271500, received funding from BEIS (UK), RCN (Norway) and RVO (Netherland), and was co-funded by the European Commission under the ERA-Net instrument of the Horizon 2020 programme. ACT Grant number 691712. J. Alcalde is funded by MICINN (Juan de la Cierva fellowship - IJC2018-036074-I). S. Ghanbari is currently supported by the Energi Simulation. Energi Simulation is also thanked for funding the chair in reactive transport simulation held by E. Mackay.Peer reviewe

    Environmental Impact Assessment and Strategic Environmental Assessment in the UK after leaving the European Union

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    The United Kingdom has voted to leave the European Union and, until the terms of the ‘Brexit’ are negotiated, this has led to considerable uncertainty over the future practice of Environmental Impact Assessment (EIA) and Strategic Environmental Assessment (SEA) in the UK. Here we show that multiple obligations exist outside the scope of the EU which mean that EIA and SEA will continue to be required in the long-term, but that their future compliance with the Directives remains unclear. We consider three scenarios for Brexit and present the implications of each; these are: signing up to the European Economic Area (EEA) Agreement; membership of the European Free Trade Association (EFTA), but not EEA, or negotiate a separate agreement. The implications of no longer being subjected to the obligations of the Directives under some scenarios are discussed and include opening the door for increasing diversity of application across the regions of the UK, and the probability of raised screening thresholds so as to reduce the burden of assessment on developers
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