2,446 research outputs found
Charge dependent azimuthal correlations in Pb--Pb collisions at TeV
Separation of charges along the extreme magnetic field created in non-central
relativistic heavy--ion collisions is predicted to be a signature of local
parity violation in strong interactions. We report on results for charge
dependent two particle azimuthal correlations with respect to the reaction
plane for Pb--Pb collisions at TeV recorded in 2010 with
ALICE at the LHC. The results are compared with measurements at RHIC energies
and against currently available model predictions for LHC. Systematic studies
of possible background effects including comparison with conventional
(parity-even) correlations simulated with Monte Carlo event generators of
heavy--ion collisions are also presented.Comment: Published in the proceedings of "Quark Matter 2011", Annecy-Franc
A City in Common: A Framework to Orchestrate Large-scale Citizen Engagement around Urban Issues
Citizen sensing is an approach that develops and uses lightweight technologies with local communities to collect, share and act upon data. In doing so it enables them to become more aware of how they can tackle local issues. We report here on the development and uptake of the 'City- Commons Framework for Citizen Sensing', a conceptual model that builds on Participatory Action Research with the aim of playing an integrating role: outlining the processes and mechanisms for ensuring sensing technologies are co-designed by citizens to address their concerns. At the heart of the framework is the idea of a city commons: a pool of community-managed resources. We discuss how the framework was used by communities in Bristol to measure and monitor the problem of damp housing
New constraints for QCD matter from improved Bayesian parameter estimation in heavy-ion collisions at LHC
The transport properties of quark-gluon plasma created in relativistic heavy-ion collisions are quantified by an improved global Bayesian analysis using the CERN Large Hadron Collider Pb-Pb data at root s(NN) = 2.76 and 5.02 TeV. The results show that the uncertainty of the extracted transport coefficients is significantly reduced by including new sophisticated collective flow observables from two collision energies for the first time. This work reveals the stronger temperature dependence of specific shear viscosity, a lower value of specific bulk viscosity, and a higher hadronization switching temperature than in the previous studies. The sensitivity analysis confirms that the precision measurements of higher-order harmonic flow and their correlations are crucial in extracting accurate values of the transport properties. (C) 2022 The Author(s). Published by Elsevier B.V.Peer reviewe
Fluctuation and flow probes of early-time correlations in relativistic heavy ion collisions
Fluctuation and correlation observables are often measured using
multi-particle correlation methods and therefore mutually probe the origins of
genuine correlations present in multi-particle distribution functions. We
investigate the common influence of correlations arising from the spatially
inhomogeneous initial state on multiplicity and momentum fluctuations as well
as flow fluctuations. Although these observables reflect different aspects of
the initial state, taken together, they can constrain a correlation scale set
at the earliest moments of the collision. We calculate both the correlation
scale in an initial stage Glasma flux tube picture and the modification to
these correlations from later stage hydrodynamic flow and find quantitative
agreement with experimental measurements over a range of collision systems and
energies.Comment: Proceedings of the 28th Winter Workshop on Nuclear Dynamics, Dorado
del Mar, Puerto Rico, April 7-14, 201
Health literacy in patients with pulmonary embolism: development and validation of the HeLP (Health Literacy in Pulmonary Embolism)-Questionnaire
Background: Pulmonary embolism (PE) is a common cardiovascular disease and health literacy is necessary to deal with its consequences after the acute event. The aim of this study was to develop and validate a new questionnaire to measure PE-specific health literacy.
Methods: A mixed-methods design with qualitative and quantitative elements was used in the development process. A literature review about health literacy concepts and instruments and interviews with patients with PE and clinicians were conducted. Quantitative analyses included factor analyses, item response theory with a graded partial credit model, and reliability analyses in different test and validation samples. Furthermore, convergent and known-groups validity and responsiveness were assessed.
Results: The qualitative results supported a concept of PE-related health literacy with four main topics: dealing with PE-related health information, disease management, health-related selfcare, and social support. An initial item pool of 91 items was developed. Further interviews and an online survey with patients with PE (n = 1,013) were used to reduce the number of items and to confirm structural validity. Confirmatory factor analyses in the final evaluation study with patients with PE (n = 238) indicated a good model fit of the four-factor structure. The Health Literacy in Pulmonary Embolism (HeLP)-Questionnaire showed good reliability (Cronbach’s alpha: 0.82 to 0.90). All four subscales were responsive toward receiving a brochure with PE-related health information.
Conclusion: The newly developed German HeLP Questionnaire comprises 23 items in four domains and showed good psychometric properties. Further evaluation of the questionnaire in different samples of patients with PE is needed
Anisotropic flow of charged particles at TeV measured with the ALICE detector
Measurements of anisotropic flow in heavy-ion collisions provide evidence for
the creation of strongly interacting matter which appears to behave as an
almost ideal fluid. Anisotropic flow signals the presence of multiple
interactions and is very sensitive to the initial spatial anisotropy of the
overlap region in non-central heavy-ion collisions. In this article we report
measurements of elliptic , triangular , quadrangular and
pentagonal flow. These measurements have been performed with 2- and
multi-particle correlation techniques.Comment: 4 pages, 4 figures, Quark Matter 2011 proceeding
Classical approximation to quantum cosmological correlations
We investigate up to which order quantum effects can be neglected in
calculating cosmological correlation functions after horizon exit. As a toy
model, we study theory on a de Sitter background for a massless
minimally coupled scalar field . We find that for tree level and one loop
contributions in the quantum theory, a good classical approximation can be
constructed, but for higher loop corrections this is in general not expected to
be possible. The reason is that loop corrections get non-negligible
contributions from loop momenta with magnitude up to the Hubble scale H, at
which scale classical physics is not expected to be a good approximation to the
quantum theory. An explicit calculation of the one loop correction to the two
point function, supports the argument that contributions from loop momenta of
scale are not negligible. Generalization of the arguments for the toy model
to derivative interactions and the curvature perturbation leads to the
conclusion that the leading orders of non-Gaussian effects generated after
horizon exit, can be approximated quite well by classical methods. Furthermore
we compare with a theorem by Weinberg. We find that growing loop corrections
after horizon exit are not excluded, even in single field inflation.Comment: 44 pages, 1 figure; v2: corrected errors, added references,
conclusions unchanged; v3: added section in which we compare with stochastic
approach; this version matches published versio
Anisotropic flow at the LHC measured with the ALICE detector
The ALICE detector at the LHC recorded first Pb-Pb collisions at 2.76 TeV in
November and December of 2010. We report on the measurements of anisotropic
flow for charged and identified particles. From the comparison with
measurements at lower energies and with model predictions we find that the
system created at these collision energies is described well by hydrodynamical
model calculations and behaves like an almost perfect fluid.Comment: 8 pages, 16 figures, plenary talk at Quark Matter 2011, May 23rd-28th
2011, Annecy, Franc
HCI policy and the smart city
While the idea of the ‘Smart City’ has attracted increasing attention from academia, industry, and government this interest has largely had a technical and technological focus. This paper identifies some of the important political and policy challenges facing the idea, the discourse, of a ‘smart city’ as a means to optimise HCI input into the ‘smart city’ debate. It then addresses that gap by detailing a research project that explored how experts in smart city research and development in the UK context responded to this policy challenge. Experts were asked questions regarding their prior experience with the “smart city”, their understandings of what it means for a city to be smart, and what policy potentials they've recognised in the smart city. The paper analyses and offers a synthesis of the responses collected throughout the research with the current policies concerning various smart city proximity, thereby providing a critical assessment of the values underlying the smart city. The paper aims to explore and present some of the policy possibilities for UK smart cities that are potentially useful for politicians, policy makers, planners, academics, and technology companies. I believe that these perspectives for policy development can be used to inform responsible development, spatially and socially inclusive technologies, and ultimately more resilient and liveable cities
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