Study of Monte Carlo approach to experimental uncertainty propagation with MSTW 2008 PDFs

We investigate the Monte Carlo approach to propagation of experimental uncertainties within the context of the established "MSTW 2008" global analysis of parton distribution functions (PDFs) of the proton at next-to-leading order in the strong coupling. We show that the Monte Carlo approach using replicas of the original data gives PDF uncertainties in good agreement with the usual Hessian approach using the standard Delta(chi^2) = 1 criterion, then we explore potential parameterisation bias by increasing the number of free parameters, concluding that any parameterisation bias is likely to be small, with the exception of the valence-quark distributions at low momentum fractions x. We motivate the need for a larger tolerance, Delta(chi^2) > 1, by making fits to restricted data sets and idealised consistent or inconsistent pseudodata. Instead of using data replicas, we alternatively produce PDF sets randomly distributed according to the covariance matrix of fit parameters including appropriate tolerance values, then we demonstrate a simpler method to produce an arbitrary number of random predictions on-the-fly from the existing eigenvector PDF sets. Finally, as a simple example application, we use Bayesian reweighting to study the effect of recent LHC data on the lepton charge asymmetry from W boson decays.Comment: 37 pages, 17 figures. v2: version published in JHEP. Supplementary material at http://mstwpdf.hepforge.org/random

Building on Julian Tudor Hart's example of anticipatory care

The prevention and delay of chronic disease is an increasing priority in all advanced health-care systems, but sustainable, effective and equitable approaches remain elusive. In a famous pioneering example in the UK, Julian Tudor Hart combined reactive and anticipatory care within routine consultations in primary medical care, while applying a population approach to delivery and audit. This approach combined the structural advantages of UK general practice, including universal coverage and the absence of user fees, with his long-term commitment to individual patients, and was associated with a 28% reduction in premature mortality over a 25-year period. The more recent, and comprehensively evaluated Scottish National Health Service demonstration project, ‘Have a Heart Paisley’, took a different approach to cardiovascular prevention and health improvement, using population screening for ascertainment, health coaches and referral to specific health improvement programmes for diet, smoking and exercise. We draw from both examples to construct a conceptual framework for anticipatory care, based on active ingredients, programme pathways and whole system approaches. While the strengths of a family practice approach are coverage, continuity, co-ordination and longterm relationships, the larger health improvement programme offered additional resources and expertise. As theory and evidence accrue, the challenge is to combine the strengths of primary medical care and health improvement, in integrated, sustainable systems of anticipatory care, addressing the heterogeneity of individual needs and solutions, while achieving high levels of coverage, continuity, co-ordination and outcome

Security-oriented infrastructures for social simulation

The JISC-funded National e-Infrastructure for Social Simulation (NeISS) project aims to develop and provide new services to social scientists and public/private sector policymakers interested in “what-if” questions that have an impact upon society and can be tackled through social simulation. For the first what-if question, a traffic simulation modelling how congestion will affect routes within a city or region projected across a time-span of decades has been identified. This paper describes the work that has been done in implementing a secure, user-oriented environment that provides seamless access to relevant nationally significant data sets such as the 2001 Census and demographic transition statistics from the British Household Panel Survey (BHPS) , and a Population Reconstruction Model (PRM) simulator, which simulates a population of individuals or households based upon these data sets

Economics of Enhanced Livestock Production

Production Economics,

Vibrational population distributions in nonequilibrium nozzle expansion flows

Experimental measurements and theoretical calculations of the vibrational population distribution in nonequilibrium nozzle expansion flows of gas mixtures are reported. These studies were directed toward determining whether vibrational energy exchange pumping could lead to laser action on the vibrational bands of a diatomic molecule. Three different types of experiments were conducted. These showed (1) that vibrational energy was preferentially transferred from N2 to CO in supersonic nozzle flows containing these gases; (2) that under some conditions this vibrational energy exchange pumping mechanism created population inversions in the vibrational levels of CO; and (3) that at large expansion ratios the magnitude of these population inversions was sufficient to sustain lasing in the nozzle. A theoretical model was developed to calculate vibrational state population distributions in gas dynamic expansions of a mixture of diatomic gases. Although only isothermal calculations have been completed, these data indicate that population inversions are predicted for conditions similar to those obtained in the nozzle expansion flows

Surface width scaling in noise reduced Eden clusters

The surface width scaling of Eden A clusters grown from a single aggregate site on the square lattice is investigated as a function of the noise reduction parameter. A two-exponent scaling ansatz is introduced and used to fit the results from simulations covering the range from fully stochastic to the zero-noise limit.Comment: 4 pages, RevTex, 3 figure

Air pollution and livestock production

The air in a livestock farming environment contains high concentrations of dust particles and gaseous pollutants. The total inhalable dust can enter the nose and mouth during normal breathing and the thoracic dust can reach into the lungs. However, it is the respirable dust particles that can penetrate further into the gas-exchange region, making it the most hazardous dust component. Prolonged exposure to high concentrations of dust particles can lead to respiratory health issues for both livestock and farming staff. Ammonia, an example of a gaseous pollutant, is derived from the decomposition of nitrous compounds. Increased exposure to ammonia may also have an effect on the health of humans and livestock. There are a number of technologies available to ensure exposure to these pollutants is minimised. Through proactive means, (the optimal design and management of livestock buildings) air quality can be improved to reduce the likelihood of risks associated with sub-optimal air quality. Once air problems have taken hold, other reduction methods need to be applied utilising a more reactive approach. A key requirement for the control of concentration and exposure of airborne pollutants to an acceptable level is to be able to conduct real-time measurements of these pollutants. This paper provides a review of airborne pollution including methods to both measure and control the concentration of pollutants in livestock buildings

The Effect of LHC Jet Data on MSTW PDFs

We consider the effect on LHC jet cross sections on partons distribution functions (PDFs), in particular the MSTW2008 set of PDFs. We first compare the published inclusive jet data to the predictions using MSTW2008, finding a very good description. We also use the parton distribution reweighting procedure to estimate the impact of these new data on the PDFs, finding that the combined ATLAS 2.76 TeV and 7 TeV data, and CMS 7 TeV data have some significant impact. We then also investigate the impact of ATLAS, CMS and D0 dijet data using the same techniques. In this case we investigate the effect of using different scale choices for the NLO cross section calculation. We find that the dijet data is generally not completely compatible with the corresponding inclusive jet data, often tending to pull PDFs, particularly the gluon distribution, away from the default values. However, the effect depends on the dijet data set used as well as the scale choice. We also note that conclusions may be affected by limiting the pull on the data luminosity chosen by the best fit, which is sometimes a number of standard deviations. Finally we include the inclusive jet data in a new PDF fit explicitly. This enables us to check the consistency of the exact result with that obtained from the reweighting procedure. There is generally good, but not full quantitative agreement. Hence, the conclusion remains that MSTW2008 PDFs already fit the published jet data well, but the central values and uncertainties are altered and improved respectively by significant, but not dramatic extent by inclusion of these data.Comment: 63 pages, 50 figures. Final version. Some added discussion and improved figure