2,529 research outputs found

    SUSY searches in multi-lepton final states with the ATLAS detector

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    Searches for the production of supersymmetric particles in protonproton collisions with the ATLAS detector at the LHC were performed with 13.0 fb‚ąí1 of data collected at ‚ąös = 8TeV. Different final states containing exactly three, or at least four light leptons (l = e,őľ) were considered. In the absence of any excess, limits were set in several different supersymmetric models

    Adaptation of clinical guidelines: literature review and proposition for a framework and procedure

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    Purpose. The development and updating of high-quality clinical practice guidelines require substantial resources. Many guideline programmes throughout the world are using similar strategies to achieve similar goals, resulting in many guidelines on the same topic. One method of using resources more efficiently and avoiding unnecessary duplication of effort would be to adapt existing guidelines. The aim was to review the literature on adaptation of guidelines and to propose a systematic approach for adaptation of guidelines. Data sources. We selected and reviewed reports describing the methods and results of adaptation of guidelines from those found by searching Medline, Internet, and reference lists of relevant papers. On the basis of this review and our experience in guideline development, we proposed a conceptual framework and procedure for adaptation of guidelines. Results. Adaptation of guidelines is performed either as an alternative to de novo guideline development or to improve guideline implementation through local tailoring of an international or national guideline. However, no validated process for the adaptation of guidelines produced in one cultural and organizational setting for use in another (i.e. trans-contextual adaptation) was found in the literature. The proposed procedure is a stepwise approach to trans-contextual adaptation, including searching for existing guidelines, quality appraisal, detailed analysis of the coherence between the evidence and the recommendations, and adaptation of the recommendations to the target context of use, taking into account the organization of the health care system and cultural context. Conclusions. Trans-contextual adaptation of guidelines is increasingly being considered as an alternative to de novo guideline development. The proposed approach should be validated and evaluated to determine if it can reduce duplication of effort and inefficient use of resources, although guaranteeing a high-quality product, compared with de novo developmen

    Second Order Perturbations in the Randall-Sundrum Infinite Brane-World Model

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    We discuss the non-linear gravitational interactions in the Randall-Sundrum single brane model. If we naively write down the 4-dimensional effective action integrating over the fifth dimension with the aid of the decomposition with respect to eigen modes of 4-dimensional d'Alembertian, the Kaluza-Klein mode coupling seems to be ill-defined. We carefully analyze second order perturbations of the gravitational field induced on the 3-brane under the assumption of the static and axial-symmetric 5-dimensional metric. It is shown that there remains no pathological feature in the Kaluza-Klein mode coupling after the summation over all different mass modes. Furthermore, the leading Kaluza-Klein corrections are shown to be sufficiently suppressed in comparison with the leading order term which is obtained by the zero mode truncation. We confirm that the 4-dimensional Einstein gravity is approximately recovered on the 3-brane up to second order perturbations.Comment: 15 pages, 2 figures, comment and reference added, typos correcte

    Melanoma cells break down LPA to establish local gradients that drive chemotactic dispersal.

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    The high mortality of melanoma is caused by rapid spread of cancer cells, which occurs unusually early in tumour evolution. Unlike most solid tumours, thickness rather than cytological markers or differentiation is the best guide to metastatic potential. Multiple stimuli that drive melanoma cell migration have been described, but it is not clear which are responsible for invasion, nor if chemotactic gradients exist in real tumours. In a chamber-based assay for melanoma dispersal, we find that cells migrate efficiently away from one another, even in initially homogeneous medium. This dispersal is driven by positive chemotaxis rather than chemorepulsion or contact inhibition. The principal chemoattractant, unexpectedly active across all tumour stages, is the lipid agonist lysophosphatidic acid (LPA) acting through the LPA receptor LPAR1. LPA induces chemotaxis of remarkable accuracy, and is both necessary and sufficient for chemotaxis and invasion in 2-D and 3-D assays. Growth factors, often described as tumour attractants, cause negligible chemotaxis themselves, but potentiate chemotaxis to LPA. Cells rapidly break down LPA present at substantial levels in culture medium and normal skin to generate outward-facing gradients. We measure LPA gradients across the margins of melanomas in vivo, confirming the physiological importance of our results. We conclude that LPA chemotaxis provides a strong drive for melanoma cells to invade outwards. Cells create their own gradients by acting as a sink, breaking down locally present LPA, and thus forming a gradient that is low in the tumour and high in the surrounding areas. The key step is not acquisition of sensitivity to the chemoattractant, but rather the tumour growing to break down enough LPA to form a gradient. Thus the stimulus that drives cell dispersal is not the presence of LPA itself, but the self-generated, outward-directed gradient

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    Measurement of the production of a W boson in association with a charm quark in pp collisions at ‚ąös = 7 TeV with the ATLAS detector