3,089 research outputs found

    Measurement of the underlying event in pp collisions using the ATLAS detector and development of a software suite for Bayesian unfolding

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    First measurements are made of the underlying event in calorimeter jet events at the LHC, using 37 pb-1 of pp collisions at √s = 7TeV, recorded during 2010 by the ATLAS detector. Results are compared for an assumed di-jet topology based on a single identified jet, and an exclusive di-jet requirement. The number of charged particles in the azimuthal region transverse to the jet axis is recorded, as well as their total and average transverse momentum. The total energy carried by all particles - charged and neutral - is also calculated, using the full calorimeter acceptance |η| < 4:8. Distributions are constructed to show the variation of these quantities versus the transverse momentum of the selected jet, over the range 20 - 800 GeV. Additional jets in the transverse region are shown to dramatically influence the measured activity. Software is developed to perform Bayesian iterative unfolding, testing closure of the process and stability with respect to the number of iterations performed. Pseudo-experiments are used to propagate systematic errors, and the intrinsic error due to unfolding is estimated. Although the correction relies on a prior probablitity distribution, model-dependence is reduced to an uncertainty comparable to or smaller than experimental systematic errors. The software is used to correct underlying event measurements for effects introduced by the ATLAS detector. Unfolded results are compared to predictions from different Monte Carlo event generators used in LHC analyses, showing general agreement in the range |η| < 2:5, but discrepancies in the forward region. Comparison with other ATLAS results shows compatible behaviour in events defined by any high-momentum charged particle, or by leptonic Z-boson decays

    Dynamic Protein Interactions of the Polycomb Repressive Complex 2 during Differentiation of Pluripotent Cells

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    Polycomb proteins assemble to form complexes with important roles in epigenetic regulation. The Polycomb Repressive Complex 2 (PRC2) modulates the di- and tri-methylation of lysine 27 on histone H3, each of which are associated with gene repression. Although three subunits, EZH1/2, SUZ12, and EED, form the catalytic core of PRC2, a wider group of proteins associate with low stoichiometry. This raises the question of whether dynamic variation of the PRC2 interactome results in alternative forms of the complex during differentiation. Here we compared the physical interactions of PRC2 in undifferentiated and differentiated states of NTERA2 pluripotent embryonic carcinoma cells. Label-free quantitative proteomics was used to assess endogenous immunoprecipitation of the EZH2 and SUZ12 subunits of PRC2. A high stringency data set reflecting the endogenous state of PRC2 was produced that included all previously reported core and associated PRC2 components, and several novel interacting proteins. Comparison of the interactomes obtained in undifferentiated and differentiated cells revealed candidate proteins that were enriched in complexes isolated from one of the two states. For example, SALL4 and ZNF281 associate with PRC2 in pluripotent cells, whereas PCL1 and SMAD3 preferentially associate with PRC2 in differentiating cells. Analysis of the mRNA and protein levels of these factors revealed that their association with PRC2 correlated with their cell state-specific expression. Taken together, we propose that dynamic changes to the PRC2 interactome during differentiation may contribute to directing its activity during cell fate transitions

    First Contact Practitioners' (FCPs) and General Practitioners' Perceptions Towards FCPs Delivering Vocational Advice to Patients with Musculoskeletal Conditions: A Qualitative Investigation of the Implementation Potential of the I-SWAP Initiative.

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    Purpose Musculoskeletal (MSK) pain is a common cause of work absence. The recent SWAP (Study of Work And Pain) randomised controlled trial (RCT) found that a brief vocational advice service for primary care patients with MSK pain led to fewer days' work absence and provided good return-on-investment. The I-SWAP (Implementation of the Study of Work And Pain) initiative aimed to deliver an implementation test-bed of the SWAP vocational advice intervention with First Contact Practitioners (FCP). This entailed adapting the SWAP vocational advice training to fit the FCP role. This qualitative investigation explored the implementation potential of FCPs delivering vocational advice for patients with MSK pain. Methods Semi-structured interviews and focus groups were conducted with 10 FCPs and 5 GPs. Data were analysed thematically and findings explored using Normalisation Process Theory (NPT). Results I-SWAP achieved a degree of 'coherence' (i.e. made sense), with both FCPs and GPs feeling FCPs were well-placed to discuss work issues with these patients. However, for many of the FCPs, addressing or modifying psychosocial and occupational barriers to return-to-work was not considered feasible within FCP consultations, and improving physical function was prioritised. Concerns were also raised that employers would not act on FCPs' recommendations regarding return-to-work. Conclusion FCPs appear well-placed to discuss work issues with MSK patients, and signpost/refer to other services; however, because they often only see patients once they are less suited to deliver other aspects of vocational advice. Future research is needed to explore how best to provide vocational advice in primary care settings

    The Relative Merits of Posterior Surgical Treatments for Multi-Level Degenerative Cervical Myelopathy Remain Uncertain: Findings from a Systematic Review.

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    OBJECTIVES: To assess the reporting of study design and characteristics in multi-level degenerative cervical myelopathy (DCM) treated by posterior surgical approaches, and perform a comparison of clinical and radiographic outcomes between different approaches. METHODS: A literature search was performed in Embase and MEDLINE between 1995-2019 using a sensitive search string combination. Studies were selected by predefined selection criteria: Full text articles in English, with >10 patients (prospective) or >50 patients (retrospective), reporting outcomes of multi-level DCM treated by posterior surgical approach. RESULTS: A total of 75 studies involving 19,510 patients, conducted worldwide, were identified. Laminoplasty was described in 56 studies (75%), followed by laminectomy with (36%) and without fusion (16%). The majority of studies were conducted in Asia (84%), in the period of 2016-2019 (51%), of which laminoplasty was studied predominantly. Twelve (16%) prospective studies and 63 (84%) retrospective studies were identified. The vast majority of studies were conducted in a single centre (95%) with clear inclusion/exclusion criteria and explicit cause of DCM. Eleven studies (15%) included patients with ossification of the posterior longitudinal ligament exclusively with cohorts of 57 to 252. The clinical and radiographic outcomes were reported with heterogeneity when comparing laminoplasty, laminectomy with and without fusion. CONCLUSIONS: Heterogeneity in the reporting of study and sample characteristics exists, as well as in clinical and radiographic outcomes, with a paucity of studies with a higher level of evidence. Future studies are needed to elucidate the clinical effectiveness of posterior surgical treatments
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