Data driven graphical applications:a fluid approach

The inclusion of high-level scripting functionality in state-of-the-art rendering APIs indicates a movement toward data-driven methodologies for structuring next generation rendering pipelines. A similar theme can be seen in the use of composition languages to deploy component software using selection and configuration of collaborating component implementations. In this paper we introduce the Fluid framework, which places particular emphasis on the use of high-level data manipulations in order to develop component based software that is flexible, extensible, and expressive. We introduce a data-driven, object oriented programming methodology to component based software development, and demonstrate how a rendering system with a similar focus on abstract manipulations can be incorporated, in order to develop a visualization application for geospatial data. In particular we describe a novel SAS script integration layer that provides access to vertex and fragment programs, producing a very controllable, responsive rendering system. The proposed system is very similar to developments speculatively planned for DirectX 10, but uses open standards and has cross platform applicability. © The Eurographics Association 2007

Variational Markov Chain Monte Carlo for Bayesian smoothing of non-linear niffusions

In this paper we develop set of novel Markov chain Monte Carlo algorithms for Bayesian smoothing of partially observed non-linear diffusion processes. The sampling algorithms developed herein use a deterministic approximation to the posterior distribution over paths as the proposal distribution for a mixture of an independence and a random walk sampler. The approximating distribution is sampled by simulating an optimized time-dependent linear diffusion process derived from the recently developed variational Gaussian process approximation method. Flexible blocking strategies are introduced to further improve mixing, and thus the efficiency, of the sampling algorithms. The algorithms are tested on two diffusion processes: one with double-well potential drift and another with SINE drift. The new algorithm's accuracy and efficiency is compared with state-of-the-art hybrid Monte Carlo based path sampling. It is shown that in practical, finite sample, applications the algorithm is accurate except in the presence of large observation errors and low observation densities, which lead to a multi-modal structure in the posterior distribution over paths. More importantly, the variational approximation assisted sampling algorithm outperforms hybrid Monte Carlo in terms of computational efficiency, except when the diffusion process is densely observed with small errors in which case both algorithms are equally efficient

A review of the factors involved in older people's decision making with regard to influenza vaccination: a literature review

Aims and objectives. The aim of this paper was to develop an understanding of the factors involved in older people's decision making with regard to influenza vaccination to inform strategies to improve vaccine uptake and reduce morbidity and mortality. Background. Influenza is a major cause of morbidity and mortality world-wide. In the UK, it accounts for 3000–6000 deaths annually; 85% of these deaths are people aged 65 and over. Despite this, and the widespread and costly annual government campaigns, some older people at risk of influenza and the associated complications remain reluctant to take advantage of the offer of vaccination. Methods. A review of the English language literature referring to older people published between 1996 and 2005 was the method used. Inclusion and exclusion criteria were identified and applied. Results. The majority of the literature was quantitative in nature, investigating personal characteristics thought to be predictors of uptake, such as age, sex, co-morbidity, educational level, income and area of residence. However, there was little discussion of the possible reasons for the significance of these factors and conflict between findings was often evident, particularly between studies employing different methodologies. Other factors identified were prior experience, concerns about the vaccine, perceived risk and advice and information. Relevance to clinical practice. The wealth of demographic information available will be useful at a strategic level in targeting groups identified as being unlikely to accept vaccination. However, the promotion of person-centred ways of working that value the health beliefs, attitudes, perceptions and subjective experiences of older people is likely to be more successful during individual encounters designed to promote acceptance. Without more research in investigating these concepts, our understanding is inevitably limited

Road transport electrification and motoring taxation in the UK

Using the Future Energy Scenarios from National Grid ESO we estimate fuel duty and VAT on fuel duty revenues from cars and vans in the UK through to 2050. We find that fuel duty and VAT on fuel duty receipts from cars and vans decrease under all scenarios. The most ambitious scenarios in terms of decarbonization, are the most problematic in terms of government revenues, which are virtually eroded by 2040. The implications are serious and require urgent action. Given that these revenues are set to all but disappear within less than two decades, a new set of road taxes needs to be introduced as a matter of urgency, potentially replacing fuel duties

Modelling frontal discontinuities in wind fields

A Bayesian procedure for the retrieval of wind vectors over the ocean using satellite borne scatterometers requires realistic prior near-surface wind field models over the oceans. We have implemented carefully chosen vector Gaussian Process models; however in some cases these models are too smooth to reproduce real atmospheric features, such as fronts. At the scale of the scatterometer observations, fronts appear as discontinuities in wind direction. Due to the nature of the retrieval problem a simple discontinuity model is not feasible, and hence we have developed a constrained discontinuity vector Gaussian Process model which ensures realistic fronts. We describe the generative model and show how to compute the data likelihood given the model. We show the results of inference using the model with Markov Chain Monte Carlo methods on both synthetic and real data

Mapping Antarctic crevasses and their evolution with deep learning applied to satellite radar imagery

The fracturing of glaciers and ice shelves in Antarctica influences their dynamics and stability. Hence, data on the evolving distribution of crevasses are required to better understand the evolution of the ice sheet, though such data have traditionally been difficult and time-consuming to generate. Here, we present an automated method of mapping crevasses on grounded and floating ice with the application of convolutional neural networks to Sentinel-1 synthetic aperture radar backscatter data. We apply this method across Antarctica to images acquired between 2015 and 2022, producing a 7.5-year record of composite fracture maps at monthly intervals and 50 m spatial resolution and showing the distribution of crevasses around the majority of the ice sheet margin. We develop a method of quantifying changes to the density of ice shelf fractures using a time series of crevasse maps and show increases in crevassing on Thwaites and Pine Island ice shelves over the observational period, with observed changes elsewhere in the Amundsen Sea dominated by the advection of existing crevasses. Using stress fields computed using the BISICLES ice sheet model, we show that much of this structural change has occurred in buttressing regions of these ice shelves, indicating a recent and ongoing link between fracturing and the developing dynamics of the Amundsen Sea sector.</p

Evaluation of variational and Markov Chain Monte Carlo methods for inference in partially observed stochastic dynamic systems

In recent work we have developed a novel variational inference method for partially observed systems governed by stochastic differential equations. In this paper we provide a comparison of the Variational Gaussian Process Smoother with an exact solution computed using a hybrid Monte Carlo approach to path sampling, applied to a stochastic double well potential model. It is demonstrated that the variational smoother provides us a very accurate estimate of mean path while marginal variance is slightly underestimated. We conclude with some remarks as to the advantages and disadvantages of the variational smoother

Dynamic response of Antarctic Peninsula Ice Sheet to potential collapse of Larsen C and George VI ice shelves

Ice shelf break-up and disintegration events over the past 5 decades have led to speed-up, thinning, and retreat of upstream tributary glaciers and increases to rates of global sea-level rise. The southward progression of these episodes indicates a climatic cause and in turn suggests that the larger Larsen C and George VI ice shelves may undergo a similar collapse in the future. However, the extent to which removal of the Larsen C and George VI ice shelves will affect upstream tributary glaciers and add to global sea levels is unknown. Here we apply numerical ice-sheet models of varying complexity to show that the centennial sea-level commitment of Larsen C embayment glaciers following immediate shelf collapse is low ( < 2.5 mm to 2100,  < 4.2 mm to 2300). Despite its large size, Larsen C does not provide strong buttressing forces to upstream basins and its collapse does not result in large additional discharge from its tributary glaciers in any of our model scenarios. In contrast, the response of inland glaciers to a collapse of the George VI Ice Shelf may add up to 8mm to global sea levels by 2100 and 22mm by 2300 due in part to the mechanism of marine ice sheet instability. Our results demonstrate the varying and relative importance to sea level of the large Antarctic Peninsula ice shelves considered to present a risk of collapse

Impact of ocean forcing on the Aurora Basin in the 21st and 22nd centuries

The grounded ice in the Totten and Dalton glaciers is an essential component of the buttressing for the marine-based Aurora basin, and hence their stability is important to the future rate of mass loss from East Antarctica. Totten and Vanderford glaciers are joined by a deep east-west running subglacial trench between the continental ice sheet and Law Dome, while a shallower trench links the Totten and Dalton glaciers. All three glaciers flow into the ocean close to the Antarctic circle and experience ocean-driven ice shelf melt rates comparable with the Amundsen Sea Embayment. We investigate this combination of trenches and ice shelves with the BISICLES adaptive mesh ice-sheet model and ocean-forcing melt rates derived from two global climate models. We find that ice shelf ablation at a rate comparable with the present day is sufficient to cause widespread grounding line retreat in an east-west direction across Totten and Dalton glaciers, with projected future warming causing faster retreat. Meanwhile, southward retreat is limited by the shallower ocean facing slopes between the coast and the bulk of the Aurora sub-glacial trench. However the two climate models produce completely different future ice shelf basal melt rates in this region: HadCM3 drives increasing sub-ice shelf melting to ~2150, while ECHAM5 shows little or no increase in sub-ice shelf melting under the two greenhouse gas forcing scenarios

The effect of interbedding on shale reservoir properties

North Sea oil is overwhelmingly generated in shales of the Upper Jurassic - basal Cretaceous Kimmeridge Clay Formation. Once generated, the oil is expelled and ultimately migrates to accumulate in sandstone or carbonate reservoirs. The source rock shales, however, still contain the portion of the oil that was not expelled. As a consequence such shales and juxtaposed non-source lithofacies can form the targets for the exploration of 'unconventional oil'.In this paper, we examine part of the Kimmeridge Clay Formation as a hybrid shale resource system within which 'Hot Shale' and organic-lean sandstone and siltstone intervals are intimately interbedded. This hybrid system can contain a greater volume of oil because of the increased storage capacity due to larger matrix porosities of the sand-silt interbeds, together with a lower adsorptive affinity in the interbedded sandstone. The relationship between the estimated volume percentages of sand and mudstone and free oil determined from Rock-Eval® S1 yields is used to place limits on the drainage of oil from source mudstone to reservoir sand at the decimeter scale. These data are used to determine oil saturations in interbedded sand-mudstone sequences at peak oil maturity. Higher values of free hydrocarbon (as evidenced by the S1 value in mudstone) suggest that more oil is being retained in the mudstone, while higher S1 values in the interbedded sands suggest the oil is being drained to saturate the larger pore spaces. High silica content in the interbeds confirms the brittleness in this mudstone-sandstone lithofacies - an important factor to be considered for fracture stimulation to successfully work in a hybrid system. The key points of this hybrid unconventional system are the thickness, storage capacity and the possibility to capture a portion of the expelled, as well as retained oil