410 research outputs found

    Surface and capillary transitions in an associating binary mixture model

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    We investigate the phase diagram of a two-component associating fluid mixture in the presence of selectively adsorbing substrates. The mixture is characterized by a bulk phase diagram which displays peculiar features such as closed loops of immiscibility. The presence of the substrates may interfere the physical mechanism involved in the appearance of these phase diagrams, leading to an enhanced tendency to phase separate below the lower critical solution point. Three different cases are considered: a planar solid surface in contact with a bulk fluid, while the other two represent two models of porous systems, namely a slit and an array on infinitely long parallel cylinders. We confirm that surface transitions, as well as capillary transitions for a large area/volume ratio, are stabilized in the one-phase region. Applicability of our results to experiments reported in the literature is discussed.Comment: 12 two-column pages, 12 figures, accepted for publication in Physical Review E; corrected versio

    Implications of structural inheritance in oblique rift zones for basin compartmentalization: Nkhata Basin, Malawi Rift (EARS)

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    The Cenozoic East African Rift System (EARS) is an exceptional example of active continental extension, providing opportunities for furthering our understanding of hydrocarbon plays within rifts. It is divided into structurally distinct western and eastern branches. The western branch comprises deep rift basins separated by transfer zones, commonly localised onto pre-existing structures, offering good regional scale hydrocarbon traps. At a basin-scale, local discrete inherited structures might also play an important role on fault localisation and hydrocarbon distribution. Here, we consider the evolution of the Central basin of the Malawi Rift, in particular the influence of pre-existing structural fabrics.Integrating basin-scale multichannel 2D, and high resolution seismic datasets we constrain the border, Mlowe-Nkhata, fault system (MNF) to the west of the basin and smaller Mbamba fault (MF) to the east and document their evolution. Intra basin structures define a series of horsts, which initiated as convergent transfers, along the basin axis. The horsts are offset along a NE-SW striking transfer fault parallel to and along strike of the onshore Karoo (Permo-Triassic) Ruhuhu graben. Discrete pre-existing structures probably determined its location and, oriented obliquely to the extension orientation it accommodated predominantly strike-slip deformation, with more slowly accrued dip-slip.To the north of this transfer fault, the overall basin architecture is asymmetric, thickening to the west throughout; while to the south, an initially symmetric graben architecture became increasingly asymmetric in sediment distribution as strain localised onto the western MNF. The presence of the axial horst increasingly focussed sediment supply to the west. As the transfer fault increased its displacement, so this axial supply was interrupted, effectively starving the south-east while ponding sediments between the western horst margin and the transfer fault. This asymmetric bathymetry and partitioned sedimentation continues to the present-day, overprinting the early basin symmetry and configuration. Sediments deposited earlier become increasingly dissected and fault juxtapositions changed at a small (10-100 m) scale. The observed influence of basin-scale transfer faults on sediment dispersal and fault compartmentalization due to pre-existing structures oblique to the extension orientation is relevant to analogous exploration settings

    Race, geography, and risk of breast cancer treatment delays: A population-based study 2004–2015

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    Background: Treatment delays affect breast cancer survival and constitute poor-quality care. Black patients experience more treatment delay, but the relationship of geography to these disparities is poorly understood. Methods: We studied a population-based, retrospective, observational cohort of patients with breast cancer in North Carolina between 2004 and 2017 from the Cancer Information and Population Health Resource, which links cancer registry and sociodemographic data to multipayer insurance claims. We included patients >18 years with Stage I–III breast cancer who received surgery or chemotherapy as their first treatment. Delay was defined as >60 days from diagnosis to first treatment. Counties were aggregated into nine Area Health Education Center regions. Race was dichotomized as Black versus non-Black. Results: Among 32,626 patients, 6190 (19.0%) were Black. Black patients were more likely to experience treatment delay >60 days (15.0% of Black vs. 8.0% of non-Black). Using race-stratified modified Poisson regression, age-adjusted relative risk of delay in the highest risk region was approximately twice that in the lowest risk region among Black (relative risk, 2.1; 95% CI, 1.6–2.6) and non-Black patients (relative risk, 1.9; 95% CI, 1.5–2.3). Adjustment for clinical and sociodemographic features only slightly attenuated interregion differences. The magnitude of the racial gap in treatment delay varied by region, from 0.0% to 9.4%. Conclusions: Geographic region was significantly associated with risk of treatment delays for both Black and non-Black patients. The magnitude of racial disparities in treatment delay varied markedly between regions. Future studies should consider both high-risk geographic regions and high-risk patient groups for intervention to prevent delays

    Ab initio Quantum and ab initio Molecular Dynamics of the Dissociative Adsorption of Hydrogen on Pd(100)

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    The dissociative adsorption of hydrogen on Pd(100) has been studied by ab initio quantum dynamics and ab initio molecular dynamics calculations. Treating all hydrogen degrees of freedom as dynamical coordinates implies a high dimensionality and requires statistical averages over thousands of trajectories. An efficient and accurate treatment of such extensive statistics is achieved in two steps: In a first step we evaluate the ab initio potential energy surface (PES) and determine an analytical representation. Then, in an independent second step dynamical calculations are performed on the analytical representation of the PES. Thus the dissociation dynamics is investigated without any crucial assumption except for the Born-Oppenheimer approximation which is anyhow employed when density-functional theory calculations are performed. The ab initio molecular dynamics is compared to detailed quantum dynamical calculations on exactly the same ab initio PES. The occurence of quantum oscillations in the sticking probability as a function of kinetic energy is addressed. They turn out to be very sensitive to the symmetry of the initial conditions. At low kinetic energies sticking is dominated by the steering effect which is illustrated using classical trajectories. The steering effects depends on the kinetic energy, but not on the mass of the molecules. Zero-point effects lead to strong differences between quantum and classical calculations of the sticking probability. The dependence of the sticking probability on the angle of incidence is analysed; it is found to be in good agreement with experimental data. The results show that the determination of the potential energy surface combined with high-dimensional dynamical calculations, in which all relevant degrees of freedon are taken into account, leads to a detailed understanding of the dissociation dynamics of hydrogen at a transition metal surface.Comment: 15 pages, 9 figures, subm. to Phys. Rev.

    Generalized Second Law of Thermodynamics in Extended Theories of Gravity

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    By employing the general expression of temperature Th=∣Îș∣/2π=12πr~A(1−r~˙A2Hr~A)T_{h}=|\kappa|/2\pi = \frac{1}{2\pi \tilde{r}_{A}}(1-\frac{\dot{\tilde{r}}_{A}}{2H\tilde{r}_{A}}) associated with the apparent horizon of a FRW universe and assuming a region of FRW universe enclosed by the apparent horizon as a thermal system in equilibrium, we are able to show that the generalized second law of thermodynamics holds in Gauss-Bonnet gravity and in more general Lovelock gravity.Comment: 10 page

    Anthocyanin-rich New Zealand blackcurrant extract reduces running-induced gastro-intestinal symptoms in the heat

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    Background: Gastrointestinal (GI) distress symptoms are a common running-induced experience for athletes training and competing in hot environmental conditions. GI distress symptoms may compromise exercise performance as well as carbohydrate digestion and absorption. Food components may affect the presence and severity of GI distress symptoms during running in hot environmental conditions. We examined the effect of anthocyanin-rich New Zealand blackcurrant (NZBC) extract on the GI distress symptoms during running in hot environmental conditions. Methods: Recreationally active males (n=12, age: 28±6 yr, BMI: 24.5±1.8 kg·m-2, V ̇O2max: 56±6 mL·kg-1·min-1) volunteered. The study had a placebo-controlled, double blind, randomized, cross-over design. In thermoneutral conditions (18°C and 40% relative humidity), participants completed an incremental exercise test to exhaustion to standardize running intensity (visit 1) and a familiarization (visit 2). Participants dosed with 7-days of NZBC extract (210 mg anthocyanins per day) or placebo. Euhydration was confirmed before the experimental visits of treadmill running for 1 hr at 65%V ̇O2max in an environmental chamber (TISS Services UK, Medtead, Hampshire, UK, 34.1±0.1 °C, 40.8±0.2% relative humidity). At 0, 30 and 60 min during the running and at 60 min following recovery in thermoneutral conditions, GI distress symptoms (i.e. upper, lower and other) were recorded with a modified visual analogue scale (doi: 10.1123/ijsnem.2018-0215). Water was available ad libitum. Results: In the placebo condition, only 2 participants (17%) reported severe symptoms. One participant reported severe dizziness and nausea in the placebo and NZBC extract condition. In the placebo condition, 11 participants (92%) reported total GI symptoms (e.g. belching, heart burn), and this was reduced to 4 participants (25%) with NZBC extract. Only one participant reported belching, nausea and stitch 60 min following recovery in the placebo condition. Upper and lower GI distress symptoms were reduced (upper, placebo: 75%, NZBC: 25% of participants; lower: placebo: 25%, NZBC extract: 17% of participants). Other GI symptoms (i.e. nausea, dizziness and stitch) were also reduced (placebo: 50%, NZBC: 25% of participants). Conclusions: Seven days intake of anthocyanin-rich NZBC extract reduced the incidence of GI distress symptoms during one-hour of treadmill running in hot environmental conditions. For most participants, the severity of GI distress symptoms pre-supplementation was considered very mild. Future research should examine the effects of NZBC extract on running with duration and intensity in conditions for which GI distress symptoms are known to be severe. Acknowledgements: Supplementation was provided by Health Currancy Ltd (United Kingdom) and CurraNZ Ltd (New Zealand). Financial support for conference attendance was obtained from Blackcurrant New Zealand Inc (New Zealand)

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

    Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

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    We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio
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