3,041 research outputs found

    Public behaviour in response to the Covid-19 pandemic: Understanding the role of group processes

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    Background In the absence of a vaccine, behaviour by the public is key to the response to the Covid-19 pandemic. Yet, as with other types of crises and emergencies, there have been doubts about the extent to which the public are able to engage effectively with the required behaviour. These doubts are based on outdated models of group psychology. Aims and argument We analyse the role of group processes in the Covid-19 pandemic in three domains: recognition of threat; adherence by the public to the required public health behaviours (and the factors that increase such adherence); and actions of the many community mutual aid groups that arose during lockdown. In each case, we draw upon the accumulated research on behaviour in emergencies and disasters as well as the latest findings in relation to the Covid-19 pandemic to show that explanations in terms of social identity processes make better sense of the patterns of evidence than alternative explanations. Conclusion If behaviour in the pandemic is a function of mutable group processes rather than fixed tendencies, then behavioural change is possible. There was evidence of significant change in behaviour from the public, particularly in the early days of the pandemic. Understanding the role of group processes means we can help design more effective interventions to support collective resilience in the public in the face of the pandemic and other threats. We draw out from the evidence a set of recommendations on facilitating the public response to Covid-19 by harnessing group processes

    In which shell-type SNRs should we look for gamma-rays and neutrinos from p-p collisions?

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    We present a simple analytic model for the various contributions to the non-thermal emission from shell type SNRs, and show that this model's results reproduce well the results of previous detailed calculations. We show that the \geq 1 TeV gamma ray emission from the shell type SNRs RX J1713.7-3946 and RX J0852.0-4622 is dominated by inverse-Compton scattering of CMB photons (and possibly infra-red ambient photons) by accelerated electrons. Pion decay (due to proton-proton collisions) is shown to account for only a small fraction, \lesssim10^-2, of the observed flux, as assuming a larger fractional contribution would imply nonthermal radio and X-ray synchrotron emission and thermal X-ray Bremsstrahlung emission that far exceed the observed radio and X-ray fluxes. Models where pion decay dominates the \geq 1 TeV flux avoid the implied excessive synchrotron emission (but not the implied excessive thermal X-ray Bremsstrahlung emission) by assuming an extremely low efficiency of electron acceleration, K_ep \lesssim 10^-4 (K_ep is the ratio of the number of accelerated electrons and the number of accelerated protons at a given energy). We argue that observations of SNRs in nearby galaxies imply a lower limit of K_ep \gtrsim 10^-3, and thus rule out K_ep values \lesssim 10^-4 (assuming that SNRs share a common typical value of K_ep). It is suggested that SNRs with strong thermal X-ray emission, rather than strong non-thermal X-ray emission, are more suitable candidates for searches of gamma rays and neutrinos resulting from proton-proton collisions. In particular, it is shown that the neutrino flux from the SNRs above is probably too low to be detected by current and planned neutrino observatories (Abridged).Comment: 13 pages, 1 figure, accepted for publication in JCAP, minor revision

    Kinetic approaches to particle acceleration at cosmic ray modified shocks

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    Kinetic approaches provide an effective description of the process of particle acceleration at shock fronts and allow to take into account the dynamical reaction of the accelerated particles as well as the amplification of the turbulent magnetic field as due to streaming instability. The latter does in turn affect the maximum achievable momentum and thereby the acceleration process itself, in a chain of causality which is typical of non-linear systems. Here we provide a technical description of two of these kinetic approaches and show that they basically lead to the same conclusions. In particular we discuss the effects of shock modification on the spectral shape of the accelerated particles, on the maximum momentum, on the thermodynamic properties of the background fluid and on the escaping and advected fluxes of accelerated particles.Comment: 22 pages, 7 figures, accepted for publication in MNRA

    Modeling the power flow in normal conductor-insulator-superconductor junctions

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    Normal conductor-insulator-superconductor (NIS) junctions promise to be interesting for x-ray and phonon sensing applications, in particular due to the expected self-cooling of the N electrode by the tunneling current. Such cooling would enable the operation of the active element of the sensor below the cryostat temperature and at a correspondingly higher sensitivity. It would also allow the use of MS junctions as microcoolers. At present, this cooling has not been realized in large area junctions (suitable for a number of detector applications). In this article, we discuss a detailed modeling of the heat flow in such junctions; we show how the heat flow into the normal electrode by quasiparticle back-tunneling and phonon absorption from quasiparticle pair recombination can overcompensate the cooling power. This provides a microscopic explanation of the self-heating effects we observe in our large area NIS junctions. The model suggests a number of possible solutions

    The X-ray Emissions from the M87 Jet: Diagnostics and Physical Interpretation

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    We reanalyze the deep Chandra observations of the M87 jet, first examined by Wilson & Yang (2002). By employing an analysis chain that includes image deconvolution, knots HST-1 and I are fully separated from adjacent emission. We find slight but significant variations in the spectral shape, with values of αx\alpha_x ranging from 1.21.6\sim 1.2-1.6. We use VLA radio observations, as well as HST imaging and polarimetry data, to examine the jet's broad-band spectrum and inquire as to the nature of particle acceleration in the jet. As shown in previous papers, a simple continuous injection model for synchrotron-emitting knots, in which both the filling factor, faccf_{acc}, of regions within which particles are accelerated and the energy spectrum of the injected particles are constant, cannot account for the X-ray flux or spectrum. Instead, we propose that faccf_{acc} is a function of position and energy and find that in the inner jet, faccEγ0.4±0.2Ee0.2±0.1f_{acc} \propto E_\gamma^{-0.4 \pm 0.2} \propto E_e^{-0.2 \pm 0.1}, and in knots A and B, faccEγ0.7±0.2Ee0.35±0.1f_{acc} \propto E_\gamma^{-0.7 \pm 0.2} \propto E_e^{-0.35 \pm 0.1}, where EγE_\gamma is the emitted photon energy and and EeE_e is the emitting electron energy. In this model, the index pp of the injected electron energy spectrum (n(Ee)Eepn(E_{e}) \propto E_{e}^{-p}) is p=2.2p=2.2 at all locations in the jet, as predicted by models of cosmic ray acceleration by ultrarelativistic shocks. There is a strong correlation between the peaks of X-ray emission and minima of optical percentage polarization, i.e., regions where the jet magnetic field is not ordered. We suggest that the X-ray peaks coincide with shock waves which accelerate the X-ray emitting electrons and cause changes in the direction of the magnetic field; the polarization is thus small because of beam averaging.Comment: Accepted for publication in ApJ; 21 pages, 9 figures, 2 tables; abstract shortened for astro-ph; Figures 1, 7 and 8 at reduced resolutio

    The Littlewood-Gowers problem

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    We show that if A is a subset of Z/pZ (p a prime) of density bounded away from 0 and 1 then the A(Z/pZ)-norm (that is the l^1-norm of the Fourier transform) of the characterstic function of A is bounded below by an absolute constant times (log p)^{1/2 - \epsilon} as p tends to infinity. This improves on the exponent 1/3 in recent work of Green and Konyagin.Comment: 31 pp. Corrected typos. Updated references

    The barriers and facilitators to implementing dementia education and training in health and social care services : a mixed-methods study

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    Background: The health and social care workforce requires access to appropriate education and training to provide quality care for people with dementia. Success of a training programme depends on staff ability to put their learning into practice through behaviour change. This study aimed to investigate the barriers and facilitators to implementation of dementia education and training in health and social care services using the Theoretical Domains Framework (TDF) and COM-B model of behaviour change. Methods: A mixed-methods design. Participants were dementia training leads, training facilitators, managers and staff who had attended training who worked in UK care homes, acute hospitals, mental health services and primary care settings. Methods were an online audit of care and training providers, online survey of trained staff and individual/group interviews with organisational training leads, training facilitators, staff who had attended dementia training and managers. Data were analysed using descriptive statistics and thematic template analysis. Results: Barriers and facilitators were analysed according the COM-B domains. “Capability” factors were not perceived as a significant barrier to training implementation. Factors which supported staff capability included the use of interactive face-to-face training, and training that was relevant to their role. Factors that increased staff “motivation” included skilled facilitation of training, trainees’ desire to learn and the provision of incentives (e.g. attendance during paid working hours, badges/certifications). “Opportunity” factors were most prevalent with lack of resources (time, financial, staffing and environmental) being the biggest perceived barrier to training implementation. The presence or not of external support from families and internal factors such as the organisational culture and its supportiveness of good dementia care and training implementation were also influential. Conclusions: A wide range of factors may present as barriers to or facilitators of dementia training implementation and behaviour change for staff. These should be considered by health and social care providers in the context of dementia training design and delivery in order to maximise potential for implementation
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