Recent constraints on the parton distributions in the proton and the measurement of αS\alpha_S from ATLAS and CMS

Recent results on cross sections sensitive to the parton distribution functions (PDFs) within the proton from the ATLAS and CMS Collaborations are presented. The potential impact on the inclusion of these data in fits to the PDFs is discussed. Recent results from fits including the data from jet, or vector boson production from the ATLAS and CMS experiments are discussed.Comment: On behalf of the ATLAS and CMS collaborations. Proceedings for Rencontres de Moriond EW 2014. 8 pages, 7 figure

Improving the low-wind performance of the AERMOD atmospheric dispersion model for predicting short-range impacts of livestock ammonia emissions.

Short-range impacts to sensitive ecosystems as a result of ammonia emitted by livestock farms are often assessed using atmospheric dispersion modelling systems such as AERMOD. These assessments evaluate mean annual atmospheric concentrations of ammonia and nitrogen deposition rates at the ecosystem location for comparison with ecosystem damage thresholds. However, predictions of mean annual atmospheric concentrations can be dominated by periods of stable night-time conditions, which can contribute significantly to mean concentrations. AERMOD has been demonstrated to overestimate concentrations in certain stable low-wind conditions and so the model could potentially overestimate the short-range impacts of livestock ammonia emissions. This paper tests several modifications to the parameterisation of AERMOD (v12345) that aim to improve model predictions in low-wind conditions. The modifications are first described and then are applied to three pig farm case studies in the USA, Denmark and Spain to assess whether the modifications improve long-term mean ammonia concentration predictions through improved model performance. For these three case studies, most of the modifications tested improved model performance as a result of reducing the long-term mean concentration predictions, with the largest effect for low- or ground-level sources (e.g. slurry lagoons or naturally ventilated housing)

Uranium solubility, speciation and complexation at high pH

Low level nuclear waste arising from UK nuclear sites, research establishments, hospitals and industry is currently disposed of at the Drigg Disposal Facility in Cumbria. Waste is packed into steel canisters before being compacted and grouted into larger steel storage containers. The aqueous chemistry of wastes, especially radionuclides, in the presence of grout material is of major interest. The gout used at the Drigg site is a mixture of Ordinary Portland Cement and Pulverised Fly Ash additive, from which ingressing water will leach high levels of calcium, sodium and potassium and produce waters of a high pH. Aerobic environments are expected to dominate over the early period of the vault life, after which the combined effect of canister corrosion and microbial activity will lead to anaerobic conditions. After a much longer period (100,000 years) anaerobic conditions may cease and yield once again an aerobic environment where migration of radionuclides may be sorption-controlled rather than on hydroxide precipitation at high pH. Work has been performed under both aerobic and anaerobic conditions to study uranium solubility in the presence of complexing ligands that may be present in the waters of the nearfield of a low-level waste disposal vault. Eleven ligands have been investigated: carbonate, phosphate, chloride, sulphate, acetate, citrate, EDTA, NTA and organic matter- humic acid, fulvic acid and iso-sacchannic acid. Anaerobic conditions were achieved by two different procedures; the first used ferrous ions in hydroxide solution and the second used dithionite in hydroxide solution. Both methods produce reducing electrode potentials and high pH. Computer software has been used to model experimental results, thereby predicting uranium solubilities and speciation, and to propose new formation constants to fit the experimental results more closely. Studies have also been perforined to measure uranium sorption by grout material at high pH in the presence of the above ligands. This work makes a significant contribution to the understanding of uranium solubility and speciation in waters. at high pH and under conditions relevant to low level nuclear waste disposal

Influence of anthropogenic and meteorological drivers on temporal patterns of ammonia emissions from agriculture in the UK

Emissions of trace gases originating from anthropogenic activities are vital input data for chemical transport models (CTMs). Other key input datasets such as meteorological drivers, and biogeochemical and physical processes have been subject to detailed investigation and research in the recent past, while the representation of spatio-temporal aspects of emission data in CTMs has been somewhat neglected. Arguably, this has less impact on the regional to hemispheric or global scale, where the grid sizes of currently applied CTMs represent well mixed average concentrations or deposition values. Evaluating model output against ground-based observations or remote sensing results on these spatial levels may not to be overly sensitive to the temporal (and spatial) profiles of emission input data. With increasing level of detail and spatio-temporal resolution, CTMs applied to determine national or local scale air quality are likely prone to be more sensitive to the spatial and temporal patterns of anthropogenic emissions. The location and timing of emission events - for instance peaks of ammonia emissions following the spring and autumn application of manure and mineral fertilisers - may well determine local concentration or deposition episodes, while not necessarily affecting seasonal or even annual mean values. In the case of agriculture, both anthropogenic activities (e.g. manure spreading and fertilizer application) and meteorological factors (e.g. temperature and seasonality) have been investigated regarding their influence on the spatiotemporal distribution of NH3 emissions (see for instance [1], [2], [4], [5] and [6]). The discussion of results in this case will focus on the impact on the deposition of acidifying and eutrophying substances, as well as the contribution to the formation of ammonium nitrates and sulphates and hence ambient concentrations of secondary particulate matter. This paper discusses results of the application of the EMEP4UK CTM on a 5 km x 5 km resolution for the whole of the United Kingdom. To evaluate the effect of changing the temporal profiles, three different model setups, e.g. using rather coarse and potentially outdated temporal profiles of the EMEP unified model, with varying degrees of detail (in this case, a monthly profile (cf. [3]) vs. 3 hourly emission values[6]) are evaluated against the AGANET measurement network stations across the UK. The discussion of results will focus on (a) the effect of temporal emission profiles on modelled vs. measured concentration/deposition values, (b) the influence on deposition of reactive nitrogen on ecosystems near ammonia sources and (c) the magnitude of influence of anthropogenic activity vs. meteorology for the dispersion of ammonia from agriculture. The results presented in this paper will help to determine the appropriate degree of detail with regard to the temporal profiles of anthropogenic emission data, as collecting detailed statistical data on anthropogenic activities for high spatially resolved model applications can be very time consuming and expensive. In addition, the effect on improving the temporal representation of emissions influenced by both anthropogenic activities and meteorological parameters can contribute to reducing uncertainties in model results that are highly relevant for policy development, e.g. covering aspects of critical load exceedance in vulnerable ecosystems or the exceedance of concentrations of PM

Apparatus for measuring high frequency currents

An apparatus for measuring high frequency currents includes a non-ferrous core current probe that is coupled to a wide-band transimpedance amplifier. The current probe has a secondary winding with a winding resistance that is substantially smaller than the reactance of the winding. The sensitivity of the current probe is substantially flat over a wide band of frequencies. The apparatus is particularly useful for measuring exposure of humans to radio frequency currents