98 research outputs found

    Finite-temperature and finite-time scaling of the directed polymer free-energy with respect to its geometrical fluctuations

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    We study the fluctuations of the directed polymer in 1+1 dimensions in a Gaussian random environment with a finite correlation length {\xi} and at finite temperature. We address the correspondence between the geometrical transverse fluctuations of the directed polymer, described by its roughness, and the fluctuations of its free-energy, characterized by its two-point correlator. Analytical arguments are provided in favor of a generic scaling law between those quantities, at finite time, non-vanishing {\xi} and explicit temperature dependence. Numerical results are in good agreement both for simulations on the discrete directed polymer and on a continuous directed polymer (with short-range correlated disorder). Applications to recent experiments on liquid crystals are discussed

    The multilevel trigger system of the DIRAC experiment

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    The multilevel trigger system of the DIRAC experiment at CERN is presented. It includes a fast first level trigger as well as various trigger processors to select events with a pair of pions having a low relative momentum typical of the physical process under study. One of these processors employs the drift chamber data, another one is based on a neural network algorithm and the others use various hit-map detector correlations. Two versions of the trigger system used at different stages of the experiment are described. The complete system reduces the event rate by a factor of 1000, with efficiency \geq95% of detecting the events in the relative momentum range of interest.Comment: 21 pages, 11 figure

    Meta-analysis of antibiotics versus appendicectomy for non-perforated acute appendicitis

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    Background: For more than a century, appendicectomy has been the treatment of choice for appendicitis. Recent trials have challenged this view. This study assessed the benefits and harms of antibiotic therapy compared with appendicectomy in patients with non-perforated appendicitis. Methods: A comprehensive search was conducted for randomized trials comparing antibiotic therapy with appendicectomy in patients with non-perforated appendicitis. Key outcomes were analysed using random-effects meta-analysis, and the quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Results: Five studies including 1116 patients reported major complications in 25 (4.9 per cent) of 510 patients in the antibiotic and 41 (8.4 per cent) of 489 in the appendicectomy group: risk difference -2.6 (95 per cent c.i. -6.3 to 1.1) per cent (low-quality evidence). Minor complications occurred in 11 (2.2 per cent) of 510 and 61 (12.5 per cent) of 489 patients respectively: risk difference -7.2 (-18.1 to 3.8) per cent (very low-quality evidence). Of 550 patients in the antibiotic group, 47 underwent appendicectomy within 1 month: pooled estimate 8.2 (95 per cent c.i. 5.2 to 11.8) per cent (high-quality evidence). Within 1 year, appendicitis recurred in 114 of 510 patients in the antibiotic group: pooled estimate 22.6 (15.6 to 30.4) per cent (high-quality evidence). For every 100 patients with non-perforated appendicitis, initial antibiotic therapy compared with prompt appendicectomy may result in 92 fewer patients receiving surgery within the first month, and 23 more experiencing recurrent appendicitis within the first year. Conclusion: The choice of medical versus surgical management in patients with clearly uncomplicated appendicitis is value-and preference-dependent, suggesting a change in practice towards shared decision-making is necessary.Peer reviewe

    Performance of an Influenza Rapid Test in Children in a Primary Healthcare Setting in Nicaragua

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    Background: Influenza is major public health threat worldwide, yet the diagnostic accuracy of rapid tests in developing country settings is not well described. Methodology/Principal Findings: To investigate the diagnostic accuracy of the QuickVue Influenza A+B test in a primary care setting in a developing country, we performed a prospective study of diagnostic accuracy of the QuickVue Influenza A+B test in comparison to reverse transcriptase-polymerase chain reaction (RT-PCR) in a primary healthcare setting in children aged 2 to 12 years in Managua, Nicaragua. The sensitivity and specificity of the QuickVue test compared to RT-PCR were 68.5 % (95 % CI 63.4, 73.3) and 98.1 % (95 % CI 96.9, 98.9), respectively, for children with a fever or history of a fever and cough and/or sore throat. Test performance was found to be lower on the first day that symptoms developed in comparison to test performance on days two or three of illness. Conclusions/Significance: Our study found that the QuickVue Influenza A+B test performed as well in a developing countr

    Perceived Conflict of Interest in Health Science Partnerships

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    University scientists conducting research on topics of potential health concern often want to partner with a range of actors, including government entities, non-governmental organizations, and private enterprises. Such partnerships can provide access to needed resources, including funding. However, those who observe the results of such partnerships may judge those results based on who is involved. This set of studies seeks to assess how people perceive two hypothetical health science research collaborations. In doing so, it also tests the utility of using procedural justice concepts to assess perceptions of research legitimacy as a theoretical way to investigate conflict of interest perceptions. Findings show that including an industry collaborator has clear negative repercussions for how people see a research partnership and that these perceptions shape people’s willingness to see the research as a legitimate source of knowledge. Additional research aimed at further communicating procedures that might mitigate the impact of industry collaboration is suggested

    DIRAC: A High Resolution Spectrometer for Pionium Detection

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    The DIRAC spectrometer has been commissioned at CERN with the aim of detecting π+π\pi^+ \pi^- atoms produced by a 24 GeV/cc high intensity proton beam in thin foil targets. A challenging apparatus is required to cope with the high interaction rates involved, the triggering of pion pairs with very low relative momentum, and the measurement of the latter with resolution around 0.6 MeV/cc. The general characteristics of the apparatus are explained and each part is described in some detail. The main features of the trigger system, data-acquisition, monitoring and setup performances are also given.Comment: 49 pages, 37 figures. Figures 1, 2, 5 and 28 are removed because of size limitations imposed by hep-ex. They don't offer essential information. Latex class file 'elsart.cls' also provide
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