2,593 research outputs found

    A Multi-coloured survey of NGC 253 with XMM-Newton

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    There is a large body of work that has used the excellent Chandra observations of nearby galaxies with neglible low mass X-ray binary (LMXB) populations. This has culminated in a ``Universal'' X-ray luminosity function (XLF) for high mass X-ray binaries (HMXBs). However, a number of methods have been used to convert from source intensities to luminosities when creating these XLFs. We have taken advantage of the XMM-Newton observations of the nearby starbursting spiral galaxy NGC 253 to test some of these methods. We find the luminosities derived from these various methods to vary by a factor of \sim3. We also find the most influential factor in the conversion from intensity to luminosity to be the absorption. We therefore conclude that a more consistent approach is required for determining the true Universal XLF for HMXBs. Ideally, this would involve individual spectral fitting of each X-ray source. Certainly, the line-of-sight absorption should be determined from the observations rather than assuming Galactic absorption. We find the best approach for obtaining an XLF from low-count data to be the splitting of the X-ray sources into two or more intensity intervals, and obtaining a conversion from intensity to flux for each group from spectral modelling of the summed spectrum of that group.Comment: To appear in the proceedings of "X-rays from Nearby Galaxies", 4-7 Septembeer 2007, 4 page

    Analysis and design of on-grade reinforced concrete track support structures

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    For the improvement of rail service, the Department of Transportation, Federal Rail Administration, is sponsoring a test track on the Atchison, Topeka, and Santa Fe Railway. The test track will contain nine separate rail support structures, including one conventional section for control and three reinforced concrete structures on grade, one slab and two beam sections. The analysis and design of these latter structures was accomplished by means of the finite element method, NASTRAN, and is presented

    Moving from a Product-Based Economy to a Service-Based Economy for a More Sustainable Future

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    Traditionally, economic growth and prosperity have been linked with the availability, production and distribution of tangible goods as well as the ability of consumers to acquire such goods. Early evidence regarding this connection dates back to Adam Smith's Wealth of Nations (1776), in which any activity not resulting in the production of a tangible good is characterized as unproductive of any value." Since then, this coupling of economic value and material production has been prevalent in both developed and developing economies throughout the world. One unintended consequence of this coupling has been the exponential increase in the amount of solid waste being generated. The reason is that any production and consumption of material goods eventually generates the equivalent amount of (or even more) waste. Exacerbating this problem is the fact that, with today's manufacturing and supply chain management technologies, it has become cheaper to dispose and replace most products rather than to repair and reuse them. This has given rise to what some call a disposable society." To put things in perspective: In 2012 households in the U.K. generated approximately 22 thousand tons of waste, which amounted to 411 kg of waste generated per person (Department for Environment, Food & Rural Affairs, 2015). During the same time period, households in the U.S. generated 251 million tons of waste, which is equivalent to a person generating approximately 2 kg of waste every day (U.S. Environmental Protection Agency, 2012). Out of these 251 million tons of total waste generated, approximately 20% of the discarded items were categorized as durable goods. The disposal of durable goods is particularly worrisome because they are typically produced using material from non- renewable resources such as iron, minerals, and petroleum-based raw materials

    Management of work-relevant upper limb disorders: a review

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    Background Upper limb disorders (ULDs) are clinically challenging and responsible for considerable work loss. There is a need to determine effective approaches for their management. Aim To determine evidence-based management strategies for work-relevant ULDs and explore whether a biopsychosocial approach is appropriate. Methods Literature review using a best evidence synthesis. Data from articles identified through systematic searching of electronic databases and citation tracking were extracted into evidence tables. The information was synthesized into high-level evidence statements, which were ordered into themes covering classification/diagnosis, epidemiology, associations/risks and management/treatment, focusing on return to work or work retention and taking account of distinctions between non-specific complaints and specific diagnoses. Results Neither biomedical treatment nor ergonomic workplace interventions alone offer an optimal solution; rather, multimodal interventions show considerable promise, particularly for occupational outcomes. Early return to work, or work retention, is an important goal for most cases and may be facilitated, where necessary, by transitional work arrangements. The emergent evidence indicates that successful management strategies require all the players to be onside and acting in a coordinated fashion; this requires engaging employers and workers to participate. Conclusions The biopsychosocial model applies: biological considerations should not be ignored, but psychosocial factors are more influential for occupational outcomes. Implementation of interventions that address the full range of psychosocial issues will require a cultural shift in the way the relationship between upper limb complaints and work is conceived and handled. Dissemination of evidence-based messages can contribute to the needed cultural shift

    An X-ray spectral survey of the disc of M31 with XMM-Newton

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    We present the results of a complete spectral survey of the X-ray point sources detected in five XMM-Newton observations along the major axis of M31 but avoiding the central bulge, aimed at establishing the population characteristics of X-ray sources in this galaxy. We obtained background subtracted spectra and lightcurves for each of the 335 X-ray point sources detected across the five observations from 2002. We also correlate our source list with those of earlier X-ray surveys and radio, optical and infra-red catalogues. Sources with more than 50 source counts are individually spectrally fit in order to create the most accurate luminosity functions of M31 to date. Based on the spectral fitting of these sources with a power law model, we observe a broad range of best fit photon index. From this distribution of best fit index, we identify 16 strong high mass X-ray binary system candidates in M31. We show the first cumulative luminosity functions created using the best fit spectral model to each source with more than 50 source counts in the disc of M31. The cumulative luminosity functions show a prominent, statistically significant flattening in the X-ray luminosity LX interval 37.0 \lesssim log LX erg s-1 \lesssim 37.5. Such a feature may also be present in the X-ray populations of several other galaxies, but at a much lower statistical significance. We investigate the number of AGN present in our source list and find that above LX ~1.4x1036 erg s-1 the observed population is statistically dominated by the point source population of M31.Comment: accepted by A&A. 24 pages, 6 figures, 7 table

    The Paradox of Power in CSR: A Case Study on Implementation

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    Purpose Although current literature assumes positive outcomes for stakeholders resulting from an increase in power associated with CSR, this research suggests that this increase can lead to conflict within organizations, resulting in almost complete inactivity on CSR. Methods A single in-depth case study, focusing on power as an embedded concept. Results Empirical evidence is used to demonstrate how some actors use CSR to improve their own positions within an organization. Resource dependence theory is used to highlight why this may be a more significant concern for CSR. Conclusions Increasing power for CSR has the potential to offer actors associated with it increased personal power, and thus can attract opportunistic actors with little interest in realizing the benefits of CSR for the company and its stakeholders. Thus power can be an impediment to furthering CSR strategy and activities at the individual and organizational level

    Spinal cord stimulation for predominant low back pain in failed back surgery syndrome: study protocol for an international multicenter randomized controlled trial (PROMISE study)

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    This is the final version of the article. Available from the publisher via the DOI in this record.BACKGROUND: Although results of case series support the use of spinal cord stimulation in failed back surgery syndrome patients with predominant low back pain, no confirmatory randomized controlled trial has been undertaken in this patient group to date. PROMISE is a multicenter, prospective, randomized, open-label, parallel-group study designed to compare the clinical effectiveness of spinal cord stimulation plus optimal medical management with optimal medical management alone in patients with failed back surgery syndrome and predominant low back pain. METHOD/DESIGN: Patients will be recruited in approximately 30 centers across Canada, Europe, and the United States. Eligible patients with low back pain exceeding leg pain and an average Numeric Pain Rating Scale score ≥5 for low back pain will be randomized 1:1 to spinal cord stimulation plus optimal medical management or to optimal medical management alone. The investigators will tailor individual optimal medical management treatment plans to their patients. Excluded from study treatments are intrathecal drug delivery, peripheral nerve stimulation, back surgery related to the original back pain complaint, and experimental therapies. Patients randomized to the spinal cord stimulation group will undergo trial stimulation, and if they achieve adequate low back pain relief a neurostimulation system using the Specify® 5-6-5 multi-column lead (Medtronic Inc., Minneapolis, MN, USA) will be implanted to capture low back pain preferentially in these patients. Outcome assessment will occur at baseline (pre-randomization) and at 1, 3, 6, 9, 12, 18, and 24 months post randomization. After the 6-month visit, patients can change treatment to that received by the other randomized group. The primary outcome is the proportion of patients with ≥50% reduction in low back pain at the 6-month visit. Additional outcomes include changes in low back and leg pain, functional disability, health-related quality of life, return to work, healthcare utilization including medication usage, and patient satisfaction. Data on adverse events will be collected. The primary analysis will follow the intention-to-treat principle. Healthcare use data will be used to assess costs and long-term cost-effectiveness. DISCUSSION: Recruitment began in January 2013 and will continue until 2016. TRIAL REGISTRATION: Clinicaltrials.gov: NCT01697358 (http://www.clinicaltrials.gov).The study is funded by Medtronic In

    Search for the rare decays B0J/ψγB^{0}\to J/\psi \gamma and Bs0J/ψγB^{0}_{s} \to J/\psi \gamma

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    A search for the rare decay of a B0B^{0} or Bs0B^{0}_{s} meson into the final state J/ψγJ/\psi\gamma is performed, using data collected by the LHCb experiment in pppp collisions at s=7\sqrt{s}=7 and 88 TeV, corresponding to an integrated luminosity of 3 fb1^{-1}. The observed number of signal candidates is consistent with a background-only hypothesis. Branching fraction values larger than 1.7×1061.7\times 10^{-6} for the B0J/ψγB^{0}\to J/\psi\gamma decay mode are excluded at 90% confidence level. For the Bs0J/ψγB^{0}_{s}\to J/\psi\gamma decay mode, branching fraction values larger than 7.4×1067.4\times 10^{-6} are excluded at 90% confidence level, this is the first branching fraction limit for this decay.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-044.htm

    A model-independent confirmation of the Z(4430)Z(4430)^- state

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    The decay B0ψ(2S)K+πB^0\to \psi(2S) K^+\pi^- is analyzed using 3 fb1\rm 3~fb^{-1} of pppp collision data collected with the LHCb detector. A model-independent description of the ψ(2S)π\psi(2S) \pi mass spectrum is obtained, using as input the KπK\pi mass spectrum and angular distribution derived directly from data, without requiring a theoretical description of resonance shapes or their interference. The hypothesis that the ψ(2S)π\psi(2S)\pi mass spectrum can be described in terms of KπK\pi reflections alone is rejected with more than 8σ\sigma significance. This provides confirmation, in a model-independent way, of the need for an additional resonant component in the mass region of the Z(4430)Z(4430)^- exotic state.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-038.htm

    A study of CPCP violation in BDhB^\mp \rightarrow Dh^\mp (h=K,πh=K,\pi) with the modes DKπ±π0D \rightarrow K^\mp \pi^\pm \pi^0, Dπ+ππ0D \rightarrow \pi^+\pi^-\pi^0 and DK+Kπ0D \rightarrow K^+K^-\pi^0

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    An analysis of the decays of BDKB^\mp \rightarrow D K^\mp and BDπB^\mp \rightarrow D \pi^\mp is presented in which the DD meson is reconstructed in the three-body final states Kπ±π0K^\mp \pi^\pm \pi^0, π+ππ0\pi^+ \pi^- \pi^0 and K+Kπ0K^+ K^- \pi^0. Using data from LHCb corresponding to an integrated luminosity of 3.0 fb1^{-1} of pppp collisions, measurements of several CPCP observables are performed. First observations are obtained of the suppressed ADS decay B[πK±π0]DπB^\mp \rightarrow [\pi^\mp K^\pm \pi^0]_D \pi^\mp and the quasi-GLW decay B[K+Kπ0]DπB^\mp \rightarrow [K^+ K^- \pi^0]_D \pi^\mp. The results are interpreted in the context of the unitarity triangle angle γ\gamma and related parameters
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