How can we learn about community socio-economic status and poverty in a developing country urban environment? An example from Johannesburg-Soweto, South Africa.

Few tested tools exist to assess poverty and socio-economic status at the community level, particularly in urban developing country environments. Furthermore, there is no real sense of what the community concept actually means. Consequently, this paper aims to describe how formative qualitative research was used to develop a quantitative tool to assess community SES in Johannesburg-Soweto in terms of the terminology used, topics covered, and how it was administered, comparing it to the South African Living Standards and Measurement Study. It also discusses the level of aggregation respondents identified as defining a local community using a drawing/mapping exercise. Focus groups (n=11) were conducted with 15-year-old adolescents and their caregivers from the 1990 Birth-to-Twenty (Bt20) cohort and key informant in-depth interviews (n=17) with prominent members working in the Bt20 communities. This research recognises the importance of involving local people in the design of data collection tools measuring poverty and human well-being

Spin Structure of the Pion in a Light-Cone Representation

The spin structure of the pion is discussed by transforming the wave function for the pion in the naive quark model into a light-cone representation. It is shown that there are higher helicity ($\lambda_{1}+\lambda_{2}=\pm1$) states in the full light-cone wave function for the pion besides the ordinary helicity ($\lambda_{1}+\lambda_{2}=0$) component wave functions as a consequence from the Melosh rotation relating spin states in light-front dynamics and those in instant-form dynamics. Some low energy properties of the pion, such as the electromagnetic form factor, the charged mean square radius, and the weak decay constant, could be interrelated in this representation with reasonable parameters.Comment: 15 Latex pages, 2 figures upon reques

Low-value clinical practices in injury care: a scoping review and expert consultation survey

BACKGROUND: Tests and treatments that are not supported by evidence and could expose patients to unnecessary harm, referred to here as low-value clinical practices, consume up to 30% of healthcare resources. Choosing Wisely and other organisations have published lists of clinical practices to be avoided. However, few apply to injury and most are based uniquely on expert consensus. We aimed to identify low-value clinical practices in acute injury care. METHODS: We conducted a scoping review targeting articles, reviews and guidelines that identified low-value clinical practices specific to injury populations. Thirty-six experts rated clinical practices on a 5-point Likert scale from clearly low-value to clearly beneficial. Clinical practices reported as low-value by at least one level I, II or III study and considered clearly or potentially low-value by at least 75% of experts were retained as candidates for low-value injury care. RESULTS: Of 50,695 citations, 815 studies were included and led to the identification of 150 clinical practices. Of these 63 were considered candidates for low-value injury care; 33 in the emergency room, 9 in trauma surgery, 15 in the intensive care unit and 5 in orthopaedics. We also identified 87 'grey zone' practices, which did not meet our criteria for low-value care. CONCLUSIONS: We identified 63 low-value clinical practices in acute injury care that are supported by empirical evidence and expert opinion. Conditional on future research, they represent potential targets for guidelines, overuse metrics and de-implementation interventions. We also identified 87 'grey zone' practices, which may be interesting targets for value-based decision-making. Our study represents an important step towards the de-implementation of low-value clinical practices in injury care. LEVEL OF EVIDENCE: III

Stellar structure and compact objects before 1940: Towards relativistic astrophysics

Since the mid-1920s, different strands of research used stars as "physics laboratories" for investigating the nature of matter under extreme densities and pressures, impossible to realize on Earth. To trace this process this paper is following the evolution of the concept of a dense core in stars, which was important both for an understanding of stellar evolution and as a testing ground for the fast-evolving field of nuclear physics. In spite of the divide between physicists and astrophysicists, some key actors working in the cross-fertilized soil of overlapping but different scientific cultures formulated models and tentative theories that gradually evolved into more realistic and structured astrophysical objects. These investigations culminated in the first contact with general relativity in 1939, when J. Robert Oppenheimer and his students George Volkoff and Hartland Snyder systematically applied the theory to the dense core of a collapsing neutron star. This pioneering application of Einstein's theory to an astrophysical compact object can be regarded as a milestone in the path eventually leading to the emergence of relativistic astrophysics in the early 1960s.Comment: 83 pages, 4 figures, submitted to the European Physical Journal

Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope

Nearby clusters and groups of galaxies are potentially bright sources of high-energy gamma-ray emission resulting from the pair-annihilation of dark matter particles. However, no significant gamma-ray emission has been detected so far from clusters in the first 11 months of observations with the Fermi Large Area Telescope. We interpret this non-detection in terms of constraints on dark matter particle properties. In particular for leptonic annihilation final states and particle masses greater than ~200 GeV, gamma-ray emission from inverse Compton scattering of CMB photons is expected to dominate the dark matter annihilation signal from clusters, and our gamma-ray limits exclude large regions of the parameter space that would give a good fit to the recent anomalous Pamela and Fermi-LAT electron-positron measurements. We also present constraints on the annihilation of more standard dark matter candidates, such as the lightest neutralino of supersymmetric models. The constraints are particularly strong when including the fact that clusters are known to contain substructure at least on galaxy scales, increasing the expected gamma-ray flux by a factor of ~5 over a smooth-halo assumption. We also explore the effect of uncertainties in cluster dark matter density profiles, finding a systematic uncertainty in the constraints of roughly a factor of two, but similar overall conclusions. In this work, we focus on deriving limits on dark matter models; a more general consideration of the Fermi-LAT data on clusters and clusters as gamma-ray sources is forthcoming.Comment: accepted to JCAP, Corresponding authors: T.E. Jeltema and S. Profumo, minor revisions to be consistent with accepted versio

Modelling spectral and timing properties of accreting black holes: the hybrid hot flow paradigm

The general picture that emerged by the end of 1990s from a large set of optical and X-ray, spectral and timing data was that the X-rays are produced in the innermost hot part of the accretion flow, while the optical/infrared (OIR) emission is mainly produced by the irradiated outer thin accretion disc. Recent multiwavelength observations of Galactic black hole transients show that the situation is not so simple. Fast variability in the OIR band, OIR excesses above the thermal emission and a complicated interplay between the X-ray and the OIR light curves imply that the OIR emitting region is much more compact. One of the popular hypotheses is that the jet contributes to the OIR emission and even is responsible for the bulk of the X-rays. However, this scenario is largely ad hoc and is in contradiction with many previously established facts. Alternatively, the hot accretion flow, known to be consistent with the X-ray spectral and timing data, is also a viable candidate to produce the OIR radiation. The hot-flow scenario naturally explains the power-law like OIR spectra, fast OIR variability and its complex relation to the X-rays if the hot flow contains non-thermal electrons (even in energetically negligible quantities), which are required by the presence of the MeV tail in Cyg X-1. The presence of non-thermal electrons also lowers the equilibrium electron temperature in the hot flow model to <100 keV, making it more consistent with observations. Here we argue that any viable model should simultaneously explain a large set of spectral and timing data and show that the hybrid (thermal/non-thermal) hot flow model satisfies most of the constraints.Comment: 26 pages, 13 figures. To be published in the Space Science Reviews and as hard cover in the Space Sciences Series of ISSI - The Physics of Accretion on to Black Holes (Springer Publisher

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

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

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

Young ghosts: ethical and methodological issues of historical research in children's geographies

This paper was published in the journal, Children's Geographies [© Taylor & Francis] and the definitive version is available at: http://dx.doi.org/10.1080/14733285.2012.693838Geographers researching children and young people have often been at the forefront of disciplinary debates in geography surrounding methodological practice and ethical considerations (Matthews et al. 1998, Valentine 1999, Pain 2004, Hemming 2008, Hopkins and Bell 2008, van Blerk and Barker 2008). In this short paper, I want to focus on a less-popular research method used by children’s geographers – archival methods (cf. Gagen 2000, 2001) – and reflect specifically on some of its methodological and ethical challenges. I argue that thinking about historical research can challenge children’s geographers to consider other types of encounter from that of the (embodied) encounter between a researcher and a child (Horton 2008). These different and multiple encounters include those between the (adult) creator of ‘material’ and a young person, a young person (as creator) and their intended audience, and the further encounter between a young person from the past and a present-day researcher during fieldwork. The spatial and temporal deferral in some of these encounters suggests a re-thinking of how we approach and conceptualise research ‘with’ young people. Furthermore, these (dis)embodied encounters can challenge ethical norms in children’s geographies such as consent, confidentiality and positionality in different but overlapping ways. I contend that children’s geographers are well versed in these ethical issues, some of which transfer well into the practice of historical research. For example, issues surrounding children’s ‘voice’ and responsibility are quite similar (as I later discuss), but there is a difference between contemporary and historical research in terms of the media involved (your own tape recordings or someone else’s recorded tapes; fresh participatory artwork or dust-covered diaries) and a different retrieval process (direct embodied research with young people or deferred connections in another building, time and place)