1,176 research outputs found

    Ultra-wide bandwidth systems for the surveillance of railway crossing Areas

    Get PDF
    Level crossings are critical elements of railway networks where a large number of accidents take place every year. With the recent enforcement of new and higher safety standards for railway transportation systems, dedicated and reliable technologies for level crossing surveillance must be introduced in order to comply with the safety requirements. In this survey the worldwide problem of level crossing surveillance is addressed, with particular attention to the recent European safety regulations. In this context, the capability of detecting, localizing, and discriminating the vehicle/obstacle that might be entrapped in a level crossing area is considered of paramount importance to save lives, and at the same time avoid costly false alarms. In this article the main solutions available today are illustrated and their pros and cons discussed. In particular, the recent ultra-wide bandwidth technology, combined with proper signal processing and backhauling over the already deployed optical fiber backbone, is shown to represent a promising solution for safety improvement in level crossings

    Planck Intermediate Results II: Comparison of Sunyaev-Zeldovich measurements from Planck and from the Arcminute Microkelvin Imager for 11 galaxy clusters

    Get PDF
    A comparison is presented of Sunyaev-Zeldovich measurements for 11 galaxy clusters as obtained by Planck and by the ground-based interferometer, the Arcminute Microkelvin Imager. Assuming a universal spherically-symmetric Generalised Navarro, Frenk & White (GNFW) model for the cluster gas pressure profile, we jointly constrain the integrated Compton-Y parameter (Y_500) and the scale radius (theta_500) of each cluster. Our resulting constraints in the Y_500-theta_500 2D parameter space derived from the two instruments overlap significantly for eight of the clusters, although, overall, there is a tendency for AMI to find the Sunyaev-Zeldovich signal to be smaller in angular size and fainter than Planck. Significant discrepancies exist for the three remaining clusters in the sample, namely A1413, A1914, and the newly-discovered Planck cluster PLCKESZ G139.59+24.18. The robustness of the analysis of both the Planck and AMI data is demonstrated through the use of detailed simulations, which also discount confusion from residual point (radio) sources and from diffuse astrophysical foregrounds as possible explanations for the discrepancies found. For a subset of our cluster sample, we have investigated the dependence of our results on the assumed pressure profile by repeating the analysis adopting the best-fitting GNFW profile shape which best matches X-ray observations. Adopting the best-fitting profile shape from the X-ray data does not, in general, resolve the discrepancies found in this subset of five clusters. Though based on a small sample, our results suggest that the adopted GNFW model may not be sufficiently flexible to describe clusters universally.Comment: update to metadata author list onl

    Morphology of the toe flexor muscles in older people with toe deformities

    Get PDF
    Objective: Despite suggestions that atrophied, or weak toe flexor muscles are associated with the formation of toe deformities, there has been little evidence to support this theory. This study aimed to determine whether the size of the toe flexor muscles differed in older people with and without toe deformities. Methods: Forty-four older adults (>60 years) were recruited for the study. Each participant had their feet assessed for the presence of hallux valgus or lesser toe deformities. Intrinsic and extrinsic toe flexor muscles were imaged with an ultrasound system using a standardised protocol. Assessor blinded muscle thickness and cross-sectional area was measured using Image J software. Results: Participants with lesser toe deformities (n=20) were found to have significantly smaller quadratus plantae (p=0.003), flexor digitorum brevis (p=0.013), abductor halluces (p=0.004) and flexor halluces brevis (p=0.005) muscles than the participants without any toe deformities (n=19). Female participants with hallux valgus (n=10) were found to have significantly smaller abductor hallucis (p=0.048) and flexor halluces brevis (p=0.013) muscles than the female participants without any toe deformities (n=10; p<0.05). Conclusion: This is the first study to use ultrasound to investigate the size of the toe flexor muscles in older people with hallux valgus and lesser toe deformities compared to otherwise healthy older adults. The size of the abductor hallucis and flexor hallucis brevis muscles were decreased in participants with hallux valgus whereas the quadratus plantae, flexor digitorum brevis, abductor hallucis and flexor halluces brevis muscles were smaller in those participants with lesser toe deformities

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

    Full text link
    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

    Get PDF
    A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

    Search for supersymmetry in events with one lepton and multiple jets in proton-proton collisions at root s=13 TeV

    Get PDF
    Peer reviewe

    Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

    Get PDF
    Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

    Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

    Get PDF
    Peer reviewe

    Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

    Get PDF
    Peer reviewe

    An embedding technique to determine ττ backgrounds in proton-proton collision data

    Get PDF
    An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe
    corecore