617 research outputs found

    Towards determining the neutrino mass hierarchy:weak lensing and galaxy clustering forecasts with baryons and intrinsic alignments

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    The capacity of Stage IV lensing surveys to measure the neutrino mass sum and differentiate between the normal and inverted mass hierarchies depends on the impact of nuisance parameters describing small-scale baryonic astrophysics and intrinsic alignments. For a Euclid-like survey, we perform the first combined weak lensing and galaxy clustering Fisher analysis with baryons, intrinsic alignments, and massive neutrinos for both hierarchies. We use a matter power spectrum generated from a halo model that captures the impact of baryonic feedback and adiabatic contraction. For weak lensing, we find that baryons cause severe degradation to forecasts of the neutrino mass sum, Σ\Sigma, approximately doubling σΣ\sigma_{\Sigma}. We show that including galaxy clustering constraints from Euclid and BOSS, and cosmic microwave background (CMB) Planck priors, can reduce this degradation to σΣ\sigma_{\Sigma} to 9% and 16% for the normal and inverted hierarchies respectively. The combined forecasts, σΣNH=0.034eV\sigma_{\Sigma_{\rm{NH}}}=0.034\, \rm{eV} and σΣIH=0.034eV\sigma_{\Sigma_{\rm{IH}}}=0.034\, \rm{eV}, preclude a meaningful distinction of the hierarchies but could be improved upon with future CMB priors on nsn_s and information from neutrinoless double beta decay to achieve a 2σ\sigma distinction. The effect of intrinsic alignments on forecasts is shown to be minimal, with σΣ\sigma_{\Sigma} even experiencing mild improvements due to information from the intrinsic alignment signal. We find that while adiabatic contraction and intrinsic alignments will require careful calibration to prevent significant biasing of Σ\Sigma, there is less risk presented by feedback from energetic events like AGN and supernovae.Comment: 24 pages, 13 figures. Several minor changes to the text, and transference of background material to appendices to match the version published by MNRA

    Exchange interaction, disorder, and stacking faults in rhombohedral graphene multilayers

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    We apply the mean-field Hartree Fock theory of gapped electronic states at charge neutrality in bilayer graphene to thin films of rhombohedral graphite with up to thirty layers. For the ground state, the order parameter (the separation of bands at the valley center) saturates to a constant non-zero value as the layer number increases, whereas the band gap decreases with layer number. We consider chiral symmetry breaking disorder in the form of random layer potentials and chiral preserving disorder in the form of random values of the interlayer coupling. The former reduces the magnitude of the mean band gap whereas the latter has a negligible effect, which is due to self-averaging within a film with a large number of layers. We determine the ground state in the presence of an individual stacking fault which results in two pairs of low-energy bands and we identify two separate order parameters. One of them determines the band gap at zero temperature, the other determines the critical temperature leading, overall, to a temperature dependence of the band gap that is distinct to that of pristine rhombohedral graphite. In the presence of stacking faults, each individual rhombohedral section with m layers contributes a pair of low-energy flat bands producing a peak in the Berry curvature located at a characteristic m-dependent wave vector. The Chern number per spin-valley flavor for the filled valence bands in the ground state is equal in magnitude to the total number of layers divided by two, the same value as for pristine rhombohedral graphite

    The impact of baryons on the sensitivity of dark energy measurements

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    Baryonic effects on large-scale structure, if not accounted for, can significantly bias dark energy constraints. As the detailed physics of the baryons is not yet well-understood, correcting for baryon effects introduces additional parameters which must be marginalized over, increasing the uncertainties on the inferred cosmological parameters. Forthcoming weak lensing surveys are aiming for percent-level precision on the dark energy equation of state, so the problem must be thoroughly examined. We use a halo model with analytic modifications which capture the impact of adiabatic contraction of baryons and feedback on the matter power spectrum, and generalize the Navarro-Frenk-White profile to account for a possible inner core. A Fisher analysis predicts degradations of 40% in the w0w_0-waw_a Figure of Merit for a Euclid-like survey, and up to 80% for other cosmological parameters. We forecast potential inner core constraints of a few kpc\mathrm{kpc}, while for a fixed inner core, adiabatic concentration and feedback parameters are constrained to a few percent. We explore the scales where baryons and dark energy contribute most to the Fisher information, finding that probing to increasingly non-linear scales does little to reduce degradation. Including external baryon information improves our forecasts, but limiting degradation to 1% requires strong priors. Adding Planck cosmic microwave background priors improves the Figure of Merit by a factor of 2.7 and almost completely recovers the individual marginalized errors on w0w_0 and waw_a. We also quantify the calibration of baryon modelling required to reduce biases of dark energy forecasts to acceptable levels for forthcoming lensing surveys.Comment: 20 pages, 17 figures. Several minor changes in the text to match version accepted for publication in MNRA

    Understanding and improving the care pathway for children with autism

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    Purpose: To describe current care pathways for children with autism including enablers and barriers, as experienced by health professionals, education professionals, and families in South Wales, UK. Design/methodology/approach: A mixed-methods approach using focus group discussions, creative writing workshops and visualisation using rich pictures. Findings: The experiences of the care pathways differed significantly across the three groups. Health professionals described the most rigidly-structured pathways, with clear entry points and outcomes. Education professionals and parents described more complex and confusing pathways, with parents assuming the responsibility of coordinating the health and education activity in a bid to link the two independent pathways. All three groups identified enablers, although these differed across the groups. The barriers were more consistent across the groups (e.g. poor communication, missing information, lack of transparency, limited post diagnosis services and access to services based on diagnosis rather than need). Practical implications: This research could inform the design of new services which are premised on multi-agency and multi-disciplinary working to ensure children with ASD receive joined up services and support. Originality/value: Although this study did not represent all professional groups or all experiences of autism, we examined three different perspectives of the ASD pathway. In addition, we triangulated high-level process maps with rich pictures and creative writing exercises, which allowed us to identify specific recommendations to improve integration and reduce duplication and gaps in provision

    Complete Genome Sequence of \u3ci\u3eLactobacillus buchneri\u3c/i\u3e NRRL B-30929, a Novel Strain from a Commercial Ethanol Plant

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    Lactobacillus buchneri strain NRRL B-30929 was a contaminant obtained from a commercial ethanol fermentation. This facultative anaerobe is unique because of its rapid growth on xylose and simultaneous fermentation of xylose and glucose. The strain utilizes a broad range of carbohydrate substrates and possesses a high tolerance to ethanol and other stresses, making it an attractive candidate for bioconversion of biomass substrates to various bioproducts. The genome sequence of NRRL B-30929 will provide insight into the unique properties of this lactic acid bacterium

    Draft genome sequence of Frankia sp. strain DC12, an atypical, noninfective, ineffective isolate from Datisca cannabina

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    Frankia sp. strain DC12, isolated from root nodules of Datisca cannabina, is a member of the fourth lineage of Frankia, which is unable to reinfect actinorhizal plants. Here, we report its 6.88-Mbp high-quality draft genome sequence, with a G+C content of 71.92% and 5,858 candidate protein-coding genes

    Are drug treatment services only for 'thieving junkie scumbags'? Drug users and the management of stigmatised identities.

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    This article uses qualitative interviews with 53 problematic drug users who had dropped out of treatment in England, UK to explore how they describe the stigmatisation of drug users and drug services. It discusses the construction of the category of the junkie through its association with un-controlled heroin use and criminality. It shows how some drug users carefully manage information about their discreditable identities by excluding themselves from this category, while acknowledging its validity for other drug users. The junkie identity was generally seen as shameful and therefore to be avoided, although it holds attractions for some drug users. For many of the interviewees, entry to treatment risked exposing their own activities as shaming, as they saw treatment as being a place that was populated by junkies and where it becomes more difficult to manage discreditable information. The treatment regime, e.g. the routine of supervised consumption of methadone,was itself seen by some as stigmatising and was also seen as hindering progress to the desired ‘normal’ life of conventional employment. Participation in the community of users of both drugs and drug services was perceived as potentially damaging to the prospects of recovery. This emphasises the importance of social capital, including links to people and opportunities outside the drug market. It also highlights the danger that using the criminal justice system to concentrate prolific offenders in treatment may have the perverse effects of excluding other people who have drug problems and of prolonging the performance of the junkie identity within treatment services. It is concluded that treatment agencies should address these issues, including through the provision of more drug services in mainstream settings, in order to ensure that drug services are not seen to be suitable only for one particularly stigmatised category of drug user
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