2,567 research outputs found

    Complex examination of the Upper Paleozoic siliciclastic rocks from southern Transdanubia, SW Hungary—Mineralogical, petrographic, and geochemical study

    Get PDF
    A vertical section of Upper Paleozoic sandstones from southern Transdanubia (Mecsek-Villány area, Tisza mega-unit, Hungary) has been analyzed for major and trace elements, including rare earth elements (REEs). In addition, the clay mineralogy of the sandstone samples and the petrography and geochemistry of gneiss and granitoid clasts extracted from the associated conglomerates have been determined. Geochemistry of the sandstone samples analyzed in this study shows that these rocks were predominantly derived from a felsic continental source; nevertheless, compositions vary systematically up-section. The Pennsylvanian (Upper Carboniferous) Téseny Formation has higher SiO(2) and lower Na(2)O, CaO, Sr, high field strength element (HFSE), and ΣREE contents relative to the Permian strata. Its high K(2)O and Rb contents together with the presence of abundant illite-sericite suggest a potassium metasomatism in this formation. Clay mineralogy and large ion lithophile element (LILE) contents of the Lower Permian Korpád Formation vary spatially and are interpreted as local variations in composition of the source region and postdepositional conditions. Zr and Hf abundances and REE patterns, however, show that this formation was derived from mature upper continental crust. The Upper Permian Cserdi Formation has higher TiO(2), Th, U, Y, Cr, and heavy (H) REE contents, and higher Cr/Th and Cr/Zr ratios relative to the underlying formations. These trends can be explained by a sedimentary system dominated by highly weathered detritus derived from combined recycled-orogen, basement-uplift, and volcanic-arc provenance in the Téseny Formation, with an increased proportion of less weathered detritus derived from combined volcanic and basement-uplift provenances in the Permian formations. Characteristics of the Cserdi unit may reflect relatively proximal derivation from a felsic volcanic source

    The demand for sports and exercise: Results from an illustrative survey

    Get PDF
    Funding from the Department of Health policy research programme was used in this study.There is a paucity of empirical evidence on the extent to which price and perceived benefits affect the level of participation in sports and exercise. Using an illustrative sample of 60 adults at Brunel University, West London, we investigate the determinants of demand for sports and exercise. The data were collected through face-to-face interviews that covered indicators of sports and exercise behaviour; money/time price and perceived benefits of participation; and socio- economic/demographic details. Count, linear and probit regression models were fitted as appropriate. Seventy eight per cent of the sample participated in sports and exercise and spent an average of £27 per month and an average of 20 min travelling per occasion of sports and exercise. The demand for sport and exercise was negatively associated with time (travel or access time) and ‘variable’ price and positively correlated with ‘fixed’ price. Demand was price inelastic, except in the case of meeting the UK government’s recommended level of participation, which is time price elastic (elasticity = −2.2). The implications of data from a larger nationally representative sample as well as the role of economic incentives in influencing uptake of sports and exercise are discussed.This article is available through the Brunel Open Access Publishing Fund

    Survey of the needs of patients with spinal cord injury: impact and priority for improvement in hand function in tetraplegics\ud

    Get PDF
    Objective: To investigate the impact of upper extremity deficit in subjects with tetraplegia.\ud \ud Setting: The United Kingdom and The Netherlands.\ud \ud Study design: Survey among the members of the Dutch and UK Spinal Cord Injury (SCI) Associations.\ud \ud Main outcome parameter: Indication of expected improvement in quality of life (QOL) on a 5-point scale in relation to improvement in hand function and seven other SCI-related impairments.\ud \ud Results: In all, 565 subjects with tetraplegia returned the questionnaire (overall response of 42%). Results in the Dutch and the UK group were comparable. A total of 77% of the tetraplegics expected an important or very important improvement in QOL if their hand function improved. This is comparable to their expectations with regard to improvement in bladder and bowel function. All other items were scored lower.\ud \ud Conclusion: This is the first study in which the impact of upper extremity impairment has been assessed in a large sample of tetraplegic subjects and compared to other SCI-related impairments that have a major impact on the life of subjects with SCI. The present study indicates a high impact as well as a high priority for improvement in hand function in tetraplegics.\ud \u

    Brane Tilings and Specular Duality

    Full text link
    We study a new duality which pairs 4d N=1 supersymmetric quiver gauge theories. They are represented by brane tilings and are worldvolume theories of D3 branes at Calabi-Yau 3-fold singularities. The new duality identifies theories which have the same combined mesonic and baryonic moduli space, otherwise called the master space. We obtain the associated Hilbert series which encodes both the generators and defining relations of the moduli space. We illustrate our findings with a set of brane tilings that have reflexive toric diagrams.Comment: 42 pages, 16 figures, 5 table

    Solving the Topological String on K3 Fibrations

    Full text link
    We present solutions of the holomorphic anomaly equations for compact two-parameter Calabi-Yau manifolds which are hypersurfaces in weighted projective space. In particular we focus on K3-fibrations where due to heterotic type II duality the topological invariants in the fibre direction are encoded in certain modular forms. The formalism employed provides holomorphic expansions of topological string amplitudes everywhere in moduli space.Comment: 60 pages, 1 figure, With an appendix by Sheldon Kat

    Designing gamified rewards to encourage repeated app selection: Effect of reward placement

    Get PDF
    Designers commonly use gamification to improve the frequency of engagement with apps, but often fail to consider the impact of placement on reward value. As rewards tend to depreciate if delayed (termed temporal discounting), placing a reward further into the future can significantly affect its ability to motivate behaviour. We examine the most effective placement of gamified rewards so as to reduce discounting and to increase the frequency an application is used. In two online studies, users were asked to choose between fictional budget tracking applications that varied in the placement of either monetary (N=70) or gamified (N=70) rewards. In both experiments we found that people more frequently used the application that provided rewards before, rather than after, the task. As predicted by temporal discounting, our work suggests that placing rewards early in the interaction sequence leads to an improvement in the perceived value of that reward, motivating further selection. We discuss the findings in the context of designing effective reward structures to encourage more frequent app engagement

    Mathematical and Statistical Techniques for Systems Medicine: The Wnt Signaling Pathway as a Case Study

    Full text link
    The last decade has seen an explosion in models that describe phenomena in systems medicine. Such models are especially useful for studying signaling pathways, such as the Wnt pathway. In this chapter we use the Wnt pathway to showcase current mathematical and statistical techniques that enable modelers to gain insight into (models of) gene regulation, and generate testable predictions. We introduce a range of modeling frameworks, but focus on ordinary differential equation (ODE) models since they remain the most widely used approach in systems biology and medicine and continue to offer great potential. We present methods for the analysis of a single model, comprising applications of standard dynamical systems approaches such as nondimensionalization, steady state, asymptotic and sensitivity analysis, and more recent statistical and algebraic approaches to compare models with data. We present parameter estimation and model comparison techniques, focusing on Bayesian analysis and coplanarity via algebraic geometry. Our intention is that this (non exhaustive) review may serve as a useful starting point for the analysis of models in systems medicine.Comment: Submitted to 'Systems Medicine' as a book chapte

    Solar-type dynamo behaviour in fully convective stars without a tachocline

    Get PDF
    In solar-type stars (with radiative cores and convective envelopes), the magnetic field powers star spots, flares and other solar phenomena, as well as chromospheric and coronal emission at ultraviolet to X-ray wavelengths. The dynamo responsible for generating the field depends on the shearing of internal magnetic fields by differential rotation. The shearing has long been thought to take place in a boundary layer known as the tachocline between the radiative core and the convective envelope. Fully convective stars do not have a tachocline and their dynamo mechanism is expected to be very different, although its exact form and physical dependencies are not known. Here we report observations of four fully convective stars whose X-ray emission correlates with their rotation periods in the same way as in Sun-like stars. As the X-ray activity - rotation relationship is a well-established proxy for the behaviour of the magnetic dynamo, these results imply that fully convective stars also operate a solar-type dynamo. The lack of a tachocline in fully convective stars therefore suggests that this is not a critical ingredient in the solar dynamo and supports models in which the dynamo originates throughout the convection zone.Comment: 6 pages, 1 figure. Accepted for publication in Nature (28 July 2016). Author's version, including Method

    Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

    Get PDF
    The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal
    corecore