1,668 research outputs found

    DPW Potentials for Compact Symmetric CMC Surfaces in S3\mathbb{S}^3

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    Inspired by the work of Heller [12], we show that there exists a DPW potential for the Lawson surface ξk1,l1\xi_{k-1, l-1} from which it is possible to reconstruct the minimal immersion f:ξk1,l1S3f: \xi_{k-1, l-1} \to \mathbb{S}^3 via the DPW method. Moreover, we extend the result to surfaces immersed in the 3-sphere with constant mean curvature which satisfy a certain symmetric condition.Comment: 20 pages, to appear in Journal of Geometry and Physic

    DPW potentials for compact symmetric CMC surfaces in the 3-sphere

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    Minimal and CMC immersions of a compact surface M in the 3-sphere can be studied via their associated family of flat SL(2, C)-connections on a rank 2 holomorphic vector bundle E over M. However, for surfaces of genus g greater than 2 it is a difficult task to describe family of holomorphic flat connections. It is easier to consider a related family of meromorphic flat connections and then reconstruct the associated family of the immersion via loop group factorisation methods. The aim of this thesis is to show that it is possible to define a family of meromorphic flat connections on a class of CMC surfaces in S3, from which it is possible to reconstruct the immersion. We consider CMC surfaces M in the 3-sphere having a group of symmetries which is finite and such that the quotient of the surface by the group is the Riemann sphere. We show that the surfaces constructed by Lawson in 1970 and by Karcher, Pinkall and Sterling in 1988, belong to this class of surfaces. We define a holomorphic vector bundle V over the Riemann sphere, equipped with a parabolic structure. We consider a family of logarithmic flat connections on V and we show that such family of logarithmic connections has a prescribed asymptotic at 0 . The main theorem of the thesis shows that the family of logarithmic connections on V can be used to define a DPW potential on the CMC surface satisfying the necessary properties to reconstruct the immersion of the surface M into the 3-sphere via loop group factorisation

    The Headphone and Loudspeaker Test-Part II: A comprehensive method for playback device screening in Internet experiments

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    HALT (The Headphone and Loudspeaker Test) Part II is a continuation of HALT Part I. The main goals of this study (HALT Part II) were (a) to develop screening tests and strategies to discriminate headphones from loudspeakers, (b) to come up with a methodological approach to combine more than two screening tests, and (c) to estimate data quality and required sample sizes for the application of screening tests. Screening Tests A and B were developed based on psychoacoustic effects. In a first laboratory study (N = 40), the two tests were evaluated with four different playback devices (circumaural and intra-aural headphones; external and laptop loudspeakers). In a final step, the two screening tests A and B and a previously established test C were validated in an Internet-based study (N = 211). Test B showed the best single-test performance (sensitivity = 80.0%, specificity = 83.2%, AUC = .844). Following an epidemiological approach, the headphone prevalence (17.67%) was determined to calculate positive and negative predictive values. For a user-oriented, parameter-based selection of suitable screening tests and the simple application of screening strategies, an online tool was programmed. HALT Part II is assumed to be a reliable procedure for planning and executing screenings to detect headphone and loudspeaker playback. Our methodological approach can be used as a generic technique for optimizing the application of any screening tests in psychological research. HALT Part I and II complement each other to form a comprehensive overall concept to control for playback conditions in Internet experiments

    Polyhedral separation via difference of convex (DC) programming

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    We consider polyhedral separation of sets as a possible tool in supervised classification. In particular, we focus on the optimization model introduced by Astorino and Gaudioso (J Optim Theory Appl 112(2):265–293, 2002) and adopt its reformulation in difference of convex (DC) form. We tackle the problem by adapting the algorithm for DC programming known as DCA. We present the results of the implementation of DCA on a number of benchmark classification datasets

    Pregnancy and COVID-19: The Possible Contribution of Vitamin D

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    Background: Vitamin D deficiency has been associated with the severity of COVID-19. The role of vitamin D in pregnant women with COVID-19 has been poorly investigated to date. The aim of this study was to evaluate the influence of vitamin D in affecting some clinical features in pregnancy between SARS-CoV-2 positive and negative patients. Methods: Vitamin D pathway related polymorphisms and 25-hydroxyvitamin D levels were quantified in pregnant women followed from the first to the third trimester of pregnancy. Vitamin D deficiency was considered with values ≤ 30 ng/mL. Results: In total, 160 women were enrolled: 23 resulted positive for at least one SARS-CoV-2 related test (molecular swab or antibody tests). Vitamin D-associated polymorphisms were able to affect vitamin D levels in SARS-CoV-2 negative and positive subjects: remarkably, all the VDR TaqICC genotype patients were negative for SARS-CoV-2. In a sub-population (118 patients), vitamin D levels correlated with pregnancy-related factors, such as alpha-fetoprotein levels. Third-trimester vitamin D levels were lower in preterm births compared to full-term pregnancy: this trend was highlighted for SARS-CoV-2 positive patients. Conclusions: This is the first study demonstrating a role of vitamin D in affecting the clinical characteristics of pregnant women during the COVID-19 era. Further studies in larger and different cohorts of patients are required to confirm these findings

    Standalone vertex finding in the ATLAS muon spectrometer

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    A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

    Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

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    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

    Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of √s=7 TeV proton-proton collisions

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    Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV

    The effectiveness and cost-effectiveness of strength and balance Exergames to reduce falls risk for people aged 55 years and older in UK assisted living facilities: A multi-centre, cluster randomised controlled trial

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    Background: Falls are the leading cause of fatal and non-fatal unintentional injuries in older people. The use of Exergames (active, gamified video-based exercises) is a possible innovative, community-based approach. This study aimed to determine the effectiveness of a tailored OTAGO/FaME based strength and balance Exergame programme for improving balance, maintaining function and reducing falls risk in older people. Methods: A two-arm cluster randomised controlled trial recruiting adults aged 55 years and older living in 18 assisted-living (sheltered housing) facilities (clusters) in the UK. Standard care (physiotherapy advice and leaflet) was compared to a tailored 12-week strength and balance Exergame programme, supported by physiotherapists or trained assistants. Complete-case analysis (intention to treat) was used to compare Berg Balance Scale (BBS) at baseline and at 12 weeks. Secondary outcomes included: fear of falling, mobility, falls risk, pain, mood, fatigue, cognition, healthcare utilisation and health-related quality of life; self-reported physical activity and falls. Results: Eighteen clusters were randomised (9 to each arm) with 56 participants allocated to the intervention and 50 to the control (78% female, mean age 78 years). Fourteen participants withdrew over the 12 weeks (both arms), mainly for ill health. There was an adjusted mean improvement in balance (BBS) of 6.2 (95% CI 2.4 to 10.0), reduced fear of falling (p=0.007) and pain (p=0.02) in Exergame group. Mean attendance at sessions was 69% (mean exercising time of 33 minutes/week). 24% of control group and 20% of Exergame group fell over trial period. The change in falls rates significantly favoured the intervention (incident rate ratio 0.31 (95% CI 0.16 to 0.62, p=0.001)). The point estimate of the incremental cost effectiveness ratio (ICER) was £15,209.80 per QALY. Using 10,000 bootstrap replications, at the lower bound of the NICE threshold of £20,000 per QALY, there was a 61% probability of Exergames being cost-effective, rising to 73% at the upper bound of £30,000 per QALY. Conclusions: Exergames, as delivered in this trial, improve balance, pain and fear of falling and are a cost-effective fall prevention strategy in assisted living facilities for people aged 55 years or older

    Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

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    The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of ttt\overline{t}, W+bbW+b\overline{b} and W+ccW+c\overline{c} is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 ±\pm 0.02 \mbox{fb}^{-1}. The WW bosons are reconstructed in the decays WνW\rightarrow\ell\nu, where \ell denotes muon or electron, while the bb and cc quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions
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