1,116 research outputs found

    Measurement of the polarisation amplitudes in B0 -> J/psi K*(892)0 decays with the LHCb experiment

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    In this thesis a measurement of the polarisation amplitudes and the corresponding strong phases of the decay B0 -> J/psi(mu+mu-)K*(892)0(K+pi-) is presented. Studying B0 -> J/psi(mu+mu-)K*(892)0(K+pi-) and B0 -> J/psi(mu+mu-)K*(892)0(K-pi+) decays separately allows for the measurement of direct CP violation. The Standard Model of particle physics does not predict any CP-violating processes for this decay channel. Thus, this analysis also serves as a search for new phenomena beyond the Standard Model. The measurement is performed using the full data sample collected with the LHCb detector in 2011 taken in proton-proton collisions at a centre-of-mass energy of 7 TeV corresponding to an integrated luminosity of approximately 1.0 fb-1. The determination of the polarisation amplitudes requires an angular analysis of the final state particles to disentangle the three possible angular momentum states. The observables are obtained using a four-dimensional maximum likelihood fit depending on the three decay angles and the decay time of the B0 meson. The values of the polarisation amplitudes and corresponding phases are determined to be R_para = 0.227 pm 0.004 pm 0.011, R_perp = 0.201 pm 0.004 pm 0.008, delta_para = -2.94 pm 0.02 pm 0.03 and delta_perp = 2.94 pm 0.02 pm 0.02, where the errors are statistical and systematic, respectively. The fit is performed in four bins of the K+pi- invariant mass to measure the fraction of the non-resonant K+pi-, so-called S-wave, contribution. Averaged over all mass bins, it is measured to be F_S = (6.4 pm 0.3 pm 1.0)%. By determining the phase difference between the resonant P-wave and the S-wave contributions in the four mass bins a two-fold ambiguity in the strong phases is resolved. Furthermore, no evidence for CP violation is observed

    Commercial Process for the Conversion of Graphite to Graphite Oxide

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    With steel and other everyday materials reaching their limits in terms of structural integrity and chemical properties, new materials are needed to provide the next breakthroughs in construction and R&D. Graphene provides incredible strengths and elasticities along with amazing electrical and thermal conductivity. Graphene based materials, the so-called supermaterials, are often limited by the lack of availability due to cost and volume. This report discusses the first large scale production of an important precursor to graphene, graphite oxide (GrO). Based on improvements of Hummer’s method, this project analyses the potential challenges associated with dealing with large quantities of corrosive and reactive substances. The process described here produces 10 tons of GrO per day through eight 3-hour batches. Graphite chunks sourced directly from the mines are crushed and refined. The powdered graphite (\u3c20 microns) is oxidized in a mixture of H2SO4 and KMnO4, which forms a reactive intermediate Mn2O7. The mixture is allowed to react for 3 h. The products are quenched using a bath of water and H2O2. The products from the quenching section go through a series of washes before the GrO product is separated and stored. The washes are processed further to recover valuable manganese compounds to reduce reagent costs. The process is not profitable at the target price of 22/kg,givinganROIof7122/kg, giving an ROI of -71%. At 25.1/kg, the ROI is 0%, and at 26/kgtheprocessisprofitablewithanROIof1526/kg the process isprofitable with an ROI of 15%. The current market price of GO is 1000/kg, so the process still significantly reduces the price of GO in the market

    Automatic and Intentional Number Processing Both Rely on Intact Right Parietal Cortex: A Combined fMRI and Neuronavigated TMS Study

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    Practice and training usually lead to performance increase in a given task. In addition, a shift from intentional toward more automatic processing mechanisms is often observed. It is currently debated whether automatic and intentional processing is subserved by the same or by different mechanism(s), and whether the same or different regions in the brain are recruited. Previous correlational evidence provided by behavioral, neuroimaging, modeling, and neuropsychological studies addressing this question yielded conflicting results. Here we used transcranial magnetic stimulation (TMS) to compare the causal influence of disrupting either left or right parietal cortex during automatic and intentional numerical processing, as reflected by the size congruity effect and the numerical distance effect, respectively. We found a functional hemispheric asymmetry within parietal cortex with only the TMS-induced right parietal disruption impairing both automatic and intentional numerical processing. In contrast, disrupting the left parietal lobe with TMS, or applying sham stimulation, did not affect performance during automatic or intentional numerical processing. The current results provide causal evidence for the functional relevance of right, but not left, parietal cortex for intentional, and automatic numerical processing, implying that at least within the parietal cortices, automatic, and intentional numerical processing rely on the same underlying hemispheric lateralization

    Dynamic networks differentiate the language ability of children with cochlear implants

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    Background: Cochlear implantation (CI) in prelingually deafened children has been shown to be an effective intervention for developing language and reading skill. However, there is a substantial proportion of the children receiving CI who struggle with language and reading. The current study–one of the first to implement electrical source imaging in CI population was designed to identify the neural underpinnings in two groups of CI children with good and poor language and reading skill. Methods: Data using high density electroencephalography (EEG) under a resting state condition was obtained from 75 children, 50 with CIs having good (HL) or poor language skills (LL) and 25 normal hearing (NH) children. We identified coherent sources using dynamic imaging of coherent sources (DICS) and their effective connectivity computing time-frequency causality estimation based on temporal partial directed coherence (TPDC) in the two CI groups compared to a cohort of age and gender matched NH children. Findings: Sources with higher coherence amplitude were observed in three frequency bands (alpha, beta and gamma) for the CI groups when compared to normal hearing children. The two groups of CI children with good (HL) and poor (LL) language ability exhibited not only different cortical and subcortical source profiles but also distinct effective connectivity between them. Additionally, a support vector machine (SVM) algorithm using these sources and their connectivity patterns for each CI group across the three frequency bands was able to predict the language and reading scores with high accuracy. Interpretation: Increased coherence in the CI groups suggest overall that the oscillatory activity in some brain areas become more strongly coupled compared to the NH group. Moreover, the different sources and their connectivity patterns and their association to language and reading skill in both groups, suggest a compensatory adaptation that either facilitated or impeded language and reading development. The neural differences in the two groups of CI children may reflect potential biomarkers for predicting outcome success in CI children

    Ionicity-dependent proton-coupled electron transfer of supramolecular self-assembled electroactive heterocycles

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    Herein, we investigate the electrochemical properties of a class of Supramolecular Self-associated Amphiphilic salts (SSAs). We show that varying ionic strength of an SSA solution can cause a switching of the thermodynamics and kinetics of electron transfer. The effect of self-assembly on proton-coupled electron transfer has implications for the understanding of electron transfer kinetics in aqueous organic redox flow batteries, especially at high concentration where organic–organic intermolecular interactions become dominant even for highly soluble organic species

    Antibodies to Kv1 potassium channel-complex proteins leucine-rich, glioma inactivated 1 protein and contactin-associated protein-2 in limbic encephalitis, Morvan’s syndrome and acquired neuromyotonia

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    Antibodies that immunoprecipitate 125I-α-dendrotoxin-labelled voltage-gated potassium channels extracted from mammalian brain tissue have been identified in patients with neuromyotonia, Morvan’s syndrome, limbic encephalitis and a few cases of adult-onset epilepsy. These conditions often improve following immunomodulatory therapies. However, the proportions of the different syndromes, the numbers with associated tumours and the relationships with potassium channel subunit antibody specificities have been unclear. We documented the clinical phenotype and tumour associations in 96 potassium channel antibody positive patients (titres >400 pM). Five had thymomas and one had an endometrial adenocarcinoma. To define the antibody specificities, we looked for binding of serum antibodies and their effects on potassium channel currents using human embryonic kidney cells expressing the potassium channel subunits. Surprisingly, only three of the patients had antibodies directed against the potassium channel subunits. By contrast, we found antibodies to three proteins that are complexed with 125I-α-dendrotoxin-labelled potassium channels in brain extracts: (i) contactin-associated protein-2 that is localized at the juxtaparanodes in myelinated axons; (ii) leucine-rich, glioma inactivated 1 protein that is most strongly expressed in the hippocampus; and (iii) Tag-1/contactin-2 that associates with contactin-associated protein-2. Antibodies to Kv1 subunits were found in three sera, to contactin-associated protein-2 in 19 sera, to leucine-rich, glioma inactivated 1 protein in 55 sera and to contactin-2 in five sera, four of which were also positive for the other antibodies. The remaining 18 sera were negative for potassium channel subunits and associated proteins by the methods employed. Of the 19 patients with contactin-associated protein-antibody-2, 10 had neuromyotonia or Morvan’s syndrome, compared with only 3 of the 55 leucine-rich, glioma inactivated 1 protein-antibody positive patients (P < 0.0001), who predominantly had limbic encephalitis. The responses to immunomodulatory therapies, defined by changes in modified Rankin scores, were good except in the patients with tumours, who all had contactin-associated-2 protein antibodies. This study confirms that the majority of patients with high potassium channel antibodies have limbic encephalitis without tumours. The identification of leucine-rich, glioma inactivated 1 protein and contactin-associated protein-2 as the major targets of potassium channel antibodies, and their associations with different clinical features, begins to explain the diversity of these syndromes; furthermore, detection of contactin-associated protein-2 antibodies should help identify the risk of an underlying tumour and a poor prognosis in future patients

    Differential branching fraction and angular analysis of the decay B0→K∗0μ+μ−

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    The angular distribution and differential branching fraction of the decay B 0→ K ∗0 μ + μ − are studied using a data sample, collected by the LHCb experiment in pp collisions at s√=7 TeV, corresponding to an integrated luminosity of 1.0 fb−1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
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