1,155 research outputs found

    Emissions vs exposure: Increasing injustice from road traffic-related air pollution in the United Kingdom

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    © 2019 The Authors This paper presents unique spatial analyses identifying substantial discrepancies in traffic-related emissions generation and exposure by socioeconomic and demographic groups. It demonstrates a compelling environmental and social injustice narrative with strong policy implications for the UK and beyond. In the first instance, this research presents a decadal update for England and Wales to Mitchell and Dorling's 2003 analysis of environmental justice in the UK. Using 2011 UK Government pollution and emissions data with 2011 UK Census socioeconomic and demographic data based on small area census geographies, this paper demonstrates a stronger relationship between age, poverty, road NOx emissions and exposure to NO2 concentrations. Areas with the highest proportions of under-fives and young adults, and poorer households, have the highest concentrations of traffic-related pollution. In addition, exclusive access to UK annual vehicle safety inspection records (‘MOT’ tests) allowed annual private vehicle NOx emissions to be spatially attributed to registered keepers. Areal analysis against Census-based socioeconomic characteristics identified that households in the poorest areas emit the least NOx and PM, whilst the least poor areas emitted the highest, per km, vehicle emissions per household through having higher vehicle ownership, owning more diesel vehicles and driving further. In conclusion, the analysis indicates that, despite more than a decade of air quality policy, environmental injustice of air pollution exposure has worsened. New evidence regarding the responsibility for generation of road traffic emissions provides a clear focus for policy development and targeted implementation

    Simulating `Complex' Problems with Quantum Monte Carlo

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    We present a new quantum Monte Carlo algorithm suitable for generically complex problems, such as systems coupled to external magnetic fields or anyons in two spatial dimensions. We find that the choice of gauge plays a nontrivial role, and can be used to reduce statistical noise in the simulation. Furthermore, it is found that noise can be greatly reduced by approximate cancellations between the phases of the (gauge dependent) statistical flux and the external magnetic flux.Comment: Revtex, 11 pages. 3 postscript files for figures attache

    Boundaries, Cusps and Caustics in the Multimagnon Continua of 1D Quantum Spin Systems

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    The multimagnon continua of 1D quantum spin systems possess several interesting singular features that may soon be accessible experimentally through inelastic neutron scattering. These include cusps and composition discontinuities in the boundary envelopes of two-magnon continuum states and discontinuities in the density of states, "caustics", on and within the continuum, which will appear as discontinuities in scattering intensity. In this note we discuss the general origins of these continuum features, and illustrate our results using the alternating Heisenberg antiferromagnetic chain and two-leg ladder as examples.Comment: 18 pages, 10 figure

    Hybrid Decays

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    The heavy quark expansion of Quantum Chromodynamics and the strong coupling flux tube picture of nonperturbative glue are employed to develop the phenomenology of hybrid meson decays. The decay mechanism explicitly couples gluonic degrees of freedom to the pair produced quarks and hence does not obey the well known, but model-dependent, selection rule which states that hybrids do not decay to pairs of L=0 mesons. However, the nonperturbative nature of gluonic excitations in the flux tube picture leads to a new selection rule: light hybrids do not decay to pairs of identical mesons. New features of the model are highlighted and partial widths are presented for several low lying hybrid states.Comment: 13 pages, 1 table, revte

    Utilising Openair to support multi-stakeholder engagement and the resolution of air quality issues

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    For key stakeholders to make informed air quality management decisions it is often necessary for in-depth data analysis to be tailored and concisely presented to meet their needs. Given the complexity of sources, the abundance of relevant data (e.g. monitoring, modelling, process data) and the spatial and temporal scale of these issues, the provision of this information can be challenging, particularly with multiple stakeholders requiring varying outputs. Using a case study which investigated PM in the vicinity of a steelworks, this paper 10 will illustrate how Openair (an open-source air pollution analysis package based on the programming language/statistical package R (http://www.openairproject.org/)) can be utilised to analyse relevant air pollution data on a spatial and temporal scale in order to support multistakeholder engagement and the resolution of air quality issues

    Magnetic field structures in star-forming regions : mid-infrared imaging polarimetry of K3-50

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    We report new imaging polarimetry observations of the Galactic compact H ii region K3-50 using CanariCam at the Gran Telescopio Canarias. We use a standard polarimetric analysis technique, first outlined by Aitken, to decompose the observed polarization images centred at 8.7, 10.3, and 12.5 μm into the emissive and absorptive components from silicate grains that are aligned with the local magnetic field. These components reveal the spatially resolved magnetic field structures across the mid-infrared emission area of K3-50. We examine these structures and show that they are consistent with previously observed features and physical models of K3-50, such as the molecular torus and the ionized outflow. We propose a 3D geometry for all the structures seen at different wavelengths. We also compute relevant physical quantities in order to estimate the associated magnetic field strengths that would be implied under various physical assumptions. We compare these results with magnetohydrodynamic simulations of protostar formation that predict the magnetic field strength and configuration. We find that the magnetic field may be dynamically important in the innermost 0.2 pc of the molecular torus, but that the torus is more likely to be rotationally supported against gravity outside this radius. Similarly, magnetic fields are unlikely to dominate the global physics of the ionized outflow, but they may be important in helping confine the flow near the cavity wall in some locations. Ours is the first application of the Aitken technique to spatially resolved magnetic field structures in multiple layers along the line of sight, effectively a method of ‘polarization tomography’Peer reviewe

    The clinical and phenotypical assessment of seronegative villous atrophy; a prospective UK centre experience evaluating 200 adult cases over a 15-year period (2000-2015).

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    BACKGROUND: Seronegative villous atrophy (SNVA) is commonly attributed to coeliac disease (CD). However, there are other causes of SNVA. More recently angiotensin-2-receptor-blockers (A2RBs) have been reported as an association but data on SNVA have been limited to centres evaluating complex case referrals and not SNVA in general. OBJECTIVES: To provide clinical outcomes and associations in a large prospective study overseeing all newcomers with SNVA. DESIGN: Over a 15-year period (2000-2015) we evaluated 200 adult patients with SNVA at a UK centre. A diagnosis of either seronegative CD (SNCD) or seronegative non-CD (SN-non-CD) was reached. Baseline comparisons were made between the groups, with 343 seropositive CD subjects serving as controls. RESULTS: Of the 200 SNVA cases, SNCD represented 31% (n=62) and SN-non-CD 69% (n=138). The human leucocyte antigen (HLA)-DQ2 and/or DQ8 genotype was present in 61%, with a 51% positive predictive value for SNCD. The breakdown of identifiable causes in the SN-non-CD group comprised infections (27%, n=54), inflammatory/immune-mediated disorders (17.5%, n=35) and drugs (6.5%, n=13; two cases related to A2RBs). However, no cause was found in 18% (n=36) and of these 72% (n=26/36) spontaneously normalised duodenal histology while consuming a gluten-enriched diet. Following multivariable logistic regression analysis an independent factor associated with SN-non-CD was non-white ethnicity (OR 10.8, 95% CI 2.2 to 52.8); in fact, 66% of non-whites had GI infections. On immunohistochemistry all groups stained positive for CD8-T-cytotoxic intraepithelial lymphocytes. However, additional CD4-T helper intraepithelial lymphocytes were occasionally seen in SN-non-CD mimicking the changes associated with refractory CD. CONCLUSIONS: Most patients with SNVA do not have CD, in particular those who are not white. Furthermore, a subgroup with no obvious aetiology will show spontaneous histological resolution while consuming gluten. These findings suggest caution in empirically prescribing a gluten-free diet without investigation

    Dark mammoth trunks in the merging galaxy NGC 1316 and a mechanism of cosmic double helices

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    NGC 1316 is a giant, elliptical galaxy containing a complex network of dark, dust features. The morphology of these features has been examined in some detail using a Hubble Space Telescope, Advanced Camera for Surveys image. It is found that most of the features are constituted of long filaments. There also exist a great number of dark structures protruding inwards from the filaments. Many of these structures are strikingly similar to elephant trunks in H II regions in the Milky Way Galaxy, although much larger. The structures, termed mammoth trunks, generally are filamentary and often have shapes resembling the letters V or Y. In some of the mammoth trunks the stem of the Y can be resolved into two or more filaments, many of which showing signs of being intertwined. A model of the mammoth trunks, related to a recent theory of elephant trunks, is proposed. Based on magnetized filaments, the model is capable of giving an account of the various shapes of the mammoth trunks observed, including the twined structures.Comment: Accepted for publication in Astrophysics & Space Scienc

    Plasma Turbulence in the Local Bubble

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    Turbulence in the Local Bubble could play an important role in the thermodynamics of the gas that is there. The best astronomical technique for measuring turbulence in astrophysical plasmas is radio scintillation. Measurements of the level of scattering to the nearby pulsar B0950+08 by Philips and Clegg in 1992 showed a markedly lower value for the line-of-sight averaged turbulent intensity parameter thanisobservedforotherpulsars,consistentwithradiowavepropagationthroughahighlyrarefiedplasma.Inthispaper,wediscusstheobservationalprogressthathasbeenmadesincethattime.Atpresent,therearefourpulsars(B0950+08,B1133+16,J0437−4715,andB0809+74)whoselinesofsightseemtoliemainlywithinthelocalbubble.Themeandensitiesandlineofsightcomponentsoftheinterstellarmagneticfieldalongtheselinesofsightaresmallerthannominalvaluesforpulsars,butnotbyasmuchexpected.Threeofthefourpulsarsalsohavemeasurementsofinterstellarscintillation.Thevalueoftheparameter than is observed for other pulsars, consistent with radio wave propagation through a highly rarefied plasma. In this paper, we discuss the observational progress that has been made since that time. At present, there are four pulsars (B0950+08, B1133+16, J0437-4715, and B0809+74) whose lines of sight seem to lie mainly within the local bubble. The mean densities and line of sight components of the interstellar magnetic field along these lines of sight are smaller than nominal values for pulsars, but not by as much expected. Three of the four pulsars also have measurements of interstellar scintillation. The value of the parameter is smaller than normal for two of them, but is completely nominal for the third. This inconclusive status of affairs could be improved by measurements and analysis of ``arcs'' in ``secondary spectra'' of pulsars.Comment: Submitted to Space Science Reviews as contribution to Proceedings of ISSI (International Space Science Institute) workshop "From the Heliosphere to the Local Bubble". Refereed version accepted for publicatio

    Single-electron transport driven by surface acoustic waves: moving quantum dots versus short barriers

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    We have investigated the response of the acoustoelectric current driven by a surface-acoustic wave through a quantum point contact in the closed-channel regime. Under proper conditions, the current develops plateaus at integer multiples of ef when the frequency f of the surface-acoustic wave or the gate voltage Vg of the point contact is varied. A pronounced 1.1 MHz beat period of the current indicates that the interference of the surface-acoustic wave with reflected waves matters. This is supported by the results obtained after a second independent beam of surface-acoustic wave was added, traveling in opposite direction. We have found that two sub-intervals can be distinguished within the 1.1 MHz modulation period, where two different sets of plateaus dominate the acoustoelectric-current versus gate-voltage characteristics. In some cases, both types of quantized steps appeared simultaneously, though at different current values, as if they were superposed on each other. Their presence could result from two independent quantization mechanisms for the acoustoelectric current. We point out that short potential barriers determining the properties of our nominally long constrictions could lead to an additional quantization mechanism, independent from those described in the standard model of 'moving quantum dots'.Comment: 25 pages, 12 figures, to be published in a special issue of J. Low Temp. Phys. in honour of Prof. F. Pobel
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