395 research outputs found

    Measurement of the electron charge asymmetry in inclusive W production in pp collisions at √s = 7 TeV in the CMS experiment.

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    In this thesis, two measurements of the electron charge asymmetry in inclusive W boson production with the CMS detector are presented. The measurements are obtained from proton-proton collision data with sqrt(s) = 7 TeV. The first measurement is performed with data corresponding to an integrated luminosity of 36 pb-1 collected by the CMS detector in 2010 and the second one uses data corresponding to 840 pb-1 collected during the first half of 2011. In proton-proton collisions, more W+ bosons are produced relative to W- due to the prevalence of up-type quarks with respect to down-type valence quarks in the proton. A measurement of this asymmetry as a function of the boson rapidity can provide valuable information on the u/d ratio within the proton. Since the boson rapidity cannot be directly measured due to the longitudinal momentum carried by the undetected neutrino, the asymmetry is measured as a function of the pseudorapidity of the charged lepton, in this case the electron, from the W decay. In both measurements, events are selected by requiring a single electron with tight selection criteria on quality of identification and measurement of the energy of the electron. The signal yield is extracted using extended maximum likelihood fits to the missing transverse energy spectrum using a set of reference template shapes for the signal, electroweak background and QCD background. The templates are obtained using Monte Carlo simulation, corrected with information from collision data events (for the signal and electroweak backgrounds), and a control sample of events obtained from an inverted selection (for the QCD background). In the first measurement the charge asymmetry is measured in 6 bins of the absolute value of the electron’s pseudorapidity and compared with predictions from theory. The statistical error ranges from 0.006 to 0.010. The increased amount of data in the second measurement allows the results to be presented in 11 bins of the absolute value of the electron’s pseudorapidity. The statistical error has been reduced and ranges from 0.003 to 0.004 and the global error is in the range 0.006 to 0.014.Open Acces

    Wireless Accelerometer for Neonatal MRI Motion Artifact Correction

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    A wireless accelerometer has been used in conjunction with a dedicated 3T neonatal MRI system installed on a Neonatal Intensive Care Unit to measure in-plane rotation which is a common problem with neonatal MRI. Rotational data has been acquired in real-time from phantoms simultaneously with MR images which shows that the wireless accelerometer can be used in close proximity to the MR system. No artifacts were observed on the MR images from the accelerometer or from the MR system on the accelerometer output. Initial attempts to correct the raw data using the measured rotational angles have been performed, but further work will be required to make a robust correction algorithm

    Flow cytometry-based evaluation of the bacterial removal efficiency of a blackwater reuse treatment plant and the microbiological changes in the associated non-potable distribution network

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    The study evaluated the changes in bacterial numbers across a full-scale membrane bioreactor (MBR) blackwater reuse system. Flow cytometry was used to quantify total and intact bacterial concentrations across the treatment train and during distribution of the recycled water. Membrane passage reduced bacterial numbers by up to 5-log units resulting in coliform-free permeate. A 2-log increase in bacterial cell concentration was subsequently observed after the granular activated carbon unit followed by a reduction in intact cells after chlorination, which corresponds to an overall intact bacteria removal of 3.4-log units. In the distribution network, the proportion of intact cells greatly depended on the free chlorine residual, with decreasing residual enabling regrowth. An initial target of 0.5 mg L−1 free chlorine ensured sufficient suppression of intact cells for up to 14 days (setting the time intervals for system flushes at times of low water usage). Bacterial regrowth was only observed when the free chlorine concentration was below 0.34 mg L−1. Such loss of residual chlorine mainly applied to distant points in the distribution network from the blackwater reuse treatment plant (BRTP). Flushing these network points for 5 min did not substantially reduce cell numbers. At points closer to the BRTP, on the other hand, flushing reduced cell numbers by up to 1.5-log units concomitant with a decreasing proportion of intact cells. Intact cell concentrations did not correlate with DOC, total nitrogen, or soluble reactive phosphate, but it was shown that dead biomass could be efficiently converted into new biomass within seven days

    Fetal Electrocardiogram (fECG) Gated MRI

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    We have developed a Magnetic Resonance Imaging (MRI)-compatible system to enable gating of a scanner to the heartbeat of a foetus for cardiac, umbilical cord flow and other possible imaging applications. We performed radiofrequency safety testing prior to a fetal electrocardiogram (fECG) gated imaging study in pregnant volunteers (n = 3). A compact monitoring device with advanced software capable of reliably detecting both the maternal electrocardiogram (mECG) and fECG simultaneously was modified by the manufacturer (Monica Healthcare, Nottingham, UK) to provide an external TTL trigger signal from the detected fECG which could be used to trigger a standard 1.5 T MR (GE Healthcare, Milwaukee, WI, USA) gating system with suitable attenuation. The MR scanner was tested by triggering rapidly during image acquisition at a typical fetal heart rate (123 beats per minute) using a simulated fECG waveform fed into the gating system. Gated MR images were also acquired from volunteers who were attending for a repeat fetal Central Nervous System (CNS) examination using an additional rapid cardiac imaging sequence triggered from the measured fECG. No adverse safety effects were encountered. This is the first time fECG gating has been used with MRI and opens up a range of new possibilities to study a developing foetus

    Specimens, slips and systems: Daniel Solander and the classification of nature at the world's first public museum, 1753-1768.

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    The British Museum, based in Montague House, Bloomsbury, opened its doors on 15 January 1759, as the world's first state-owned public museum. The Museum's collection mostly originated from Sir Hans Sloane (1660-1753), whose vast holdings were purchased by Parliament shortly after his death. The largest component of this collection was objects of natural history, including a herbarium made up of 265 bound volumes, many of which were classified according to the late seventeenth-century system of John Ray (1627-1705). The 1750s saw the emergence of Linnaean binomial nomenclature, following the publication of Carl Linnaeus' Species Plantarum (1753) and Systema Naturae (1758). In order to adopt this new system for their collections, the Trustees of the British Museum chose to employ the Swedish naturalist and former student of Linnaeus, Daniel Solander (1733-1782) to reclassify the collection. Solander was ordered to devise a new system for classifying and cataloguing Sloane's natural history collection, which would allow both Linnaeans and those who followed earlier systems to access it. Solander's work was essential for allowing the British Museum to realize its aim of becoming a public centre of learning, adapting the collection to reflect the diversity of classificatory practices which were existent by the 1760s. This task engaged Solander until 1768, when he received an offer from Joseph Banks (1743-1820) to accompany him on HMS Endeavour to the Pacific

    Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

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    This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

    Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation