43 research outputs found

    Microcomputer-based artificial vision support system for real-time image processing for camera-driven visual prostheses

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    It is difficult to predict exactly what blind subjects with camera-driven visual prostheses (e.g., retinal implants) can perceive. Thus, it is prudent to offer them a wide variety of image processing filters and the capability to engage these filters repeatedly in any userdefined order to enhance their visual perception. To attain true portability, we employ a commercial off-the-shelf battery-powered general purpose Linux microprocessor platform to create the microcomputer-based artificial vision support system (µAVS^2) for real-time image processing. Truly standalone, µAVS^2 is smaller than a deck of playing cards, lightweight, fast, and equipped with USB, RS- 232 and Ethernet interfaces. Image processing filters on µAVS^2 operate in a user-defined linear sequential-loop fashion, resulting in vastly reduced memory and CPU requirements during execution. µAVS^2 imports raw video frames from a USB or IP camera, performs image processing, and issues the processed data over an outbound Internet TCP/IP or RS-232 connection to the visual prosthesis system. Hence, µAVS^2 affords users of current and future visual prostheses independent mobility and the capability to customize the visual perception generated. Additionally, µAVS^2 can easily be reconfigured for other prosthetic systems. Testing of µAVS^2 with actual retinal implant carriers is envisioned in the near future

    Accessible Web Page Design for the Visually Impaired: A Case Study

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    Section 508 of the Rehabilitations Act of 1973 states that federal agencies are required to maintain accessible web-based information for persons with disabilities, namely, visual impairments. Studies spanning over 1 decade conducted by The American Foundation for the Blind and Towson University’s Universal Usability Lab investigated federal home pages for Section 508 violations. Both studies concluded that numerous university, corporate, federal, and federal contractor websites are largely inaccessible to people with disabilities—specifically in terms of clarity, consistency, and fidelity to standards. Due to inconsistencies across federal agencies, constant website updates, and webmaster turnaround, there is a need for practical guidelines for web page design compliant with Section 508, the Americans with Disabilities Act, and the World Wide Web Consortium’s Web Content Accessibility Guidelines, with particular focus on the visually impaired

    Direct observation of the dead-cone effect in quantum chromodynamics

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    The direct measurement of the QCD dead cone in charm quark fragmentation is reported, using iterative declustering of jets tagged with a fully reconstructed charmed hadron

    Neutron emission in ultraperipheral Pb-Pb collisions at sNN\sqrt {s_{NN}} = 5.02 TeV

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    In ultraperipheral collisions (UPCs) of relativistic nuclei without overlap of nuclear densities, the two nuclei are excited by the Lorentz-contracted Coulomb fields of their collision partners. In these UPCs, the typical nuclear excitation energy is below a few tens of MeV, and a small number of nucleons are emitted in electromagnetic dissociation (EMD) of primary nuclei, in contrast to complete nuclear fragmentation in hadronic interactions. The cross sections of emission of given numbers of neutrons in UPCs of 208^{208}Pb nuclei at sNN=5.02\sqrt{s_{\mathrm{NN}}}=5.02~TeV were measured with the neutron zero degree calorimeters (ZDCs) of the ALICE detector at the LHC, exploiting a similar technique to that used in previous studies performed at sNN=2.76\sqrt{s_{\mathrm{NN}}}=2.76~TeV. In addition, the cross sections for the exclusive emission of 1, 2, 3, 4 and 5 forward neutrons in the EMD, not accompanied by the emission of forward protons, and thus mostly corresponding to the production of 207,206,205,204,203^{207,206,205,204,203}Pb, respectively, were measured for the first time. The predictions from the available models describe the measured cross sections well. These cross sections can be used for evaluating the impact of secondary nuclei on the LHC components, in particular, on superconducting magnets, and also provide useful input for the design of the Future Circular Collider (FCC-hh).In ultraperipheral collisions (UPCs) of relativistic nuclei without overlap of nuclear densities, the two nuclei are excited by the Lorentz-contracted Coulomb fields of their collision partners. In these UPCs, the typical nuclear excitation energy is below a few tens of MeV, and a small number of nucleons are emitted in electromagnetic dissociation (EMD) of primary nuclei, in contrast to complete nuclear fragmentation in hadronic interactions. The cross sections of emission of given numbers of neutrons in UPCs of Pb208 nuclei at sNN=5.02 TeV were measured with the neutron zero degree calorimeters (ZDCs) of the ALICE detector at the LHC, exploiting a similar technique to that used in previous studies performed at sNN=2.76 TeV. In addition, the cross sections for the exclusive emission of one, two, three, four, and five forward neutrons in the EMD, not accompanied by the emission of forward protons, and thus mostly corresponding to the production of Pb207,206,205,204,203, respectively, were measured for the first time. The predictions from the available models describe the measured cross sections well. These cross sections can be used for evaluating the impact of secondary nuclei on the LHC components, in particular, on superconducting magnets, and also provide useful input for the design of the Future Circular Collider (FCC-hh).In ultraperipheral collisions (UPCs) of relativistic nuclei without overlap of nuclear densities, the two nuclei are excited by the Lorentz-contracted Coulomb fields of their collision partners. In these UPCs, the typical nuclear excitation energy is below a few tens of MeV, and a small number of nucleons are emitted in electromagnetic dissociation (EMD) of primary nuclei, in contrast to complete nuclear fragmentation in hadronic interactions. The cross sections of emission of given numbers of neutrons in UPCs of 208^{208}Pb nuclei at sNN=5.02\sqrt{s_{\mathrm{NN}}}=5.02 TeV were measured with the neutron zero degree calorimeters (ZDCs) of the ALICE detector at the LHC, exploiting a similar technique to that used in previous studies performed at sNN=2.76\sqrt{s_{\mathrm{NN}}}=2.76 TeV. In addition, the cross sections for the exclusive emission of one, two, three, four, and five forward neutrons in the EMD, not accompanied by the emission of forward protons, and thus mostly corresponding to the production of 207,206,205,204,203^{207,206,205,204,203}Pb, respectively, were measured for the first time. The predictions from the available models describe the measured cross sections well. These cross sections can be used for evaluating the impact of secondary nuclei on the LHC components, in particular, on superconducting magnets, and also provide useful input for the design of the Future Circular Collider (FCC-hh)

    Constraining the KN{\overline{\textrm{K}}}{\textrm{N}} coupled channel dynamics using femtoscopic correlations at the LHC

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    The interaction of K{\rm{K}^{-}} with protons is characterised by the presence of several coupled channels, systems like K0{\rm \overline{K}^0}n and πΣ{\pi\Sigma} with a similar mass and the same quantum numbers as the K{\rm{K}^{-}} p state. The strengths of these couplings to the K{\rm{K}^{-}}p system are of crucial importance for the understanding of the nature of the Λ(1405)\Lambda(1405) resonance and of the attractive K{\rm{K}^{-}} p strong interaction. In this article, we present measurements of the K{\rm{K}^{-}}p correlation functions in relative momentum space obtained in pp collisions at s=13\sqrt{s} = 13~TeV, in p-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}} = 5.02~TeV, and (semi)peripheral Pb-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}} = 5.02~TeV. The emitting source size, composed of a core radius anchored to the K+{\rm{K}^{+}}p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the K0{\rm \overline{K}^0}n and πΣ{\pi\Sigma} inelastic channels on the measured K{\rm{K}^{-}}p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights ω\omega, necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured K{\rm{K}^{-}}p interaction indicates that, while the \mbox{πΣ{\pi\Sigma}-K{\rm{K}^{-}}p} dynamics is well reproduced by the model, the coupling to the K0{\rm \overline{K}^0}n channel in the model is currently underestimated.The interaction of K\textrm{K}^{-}with protons is characterised by the presence of several coupled channels, systems like K0{\overline{\textrm{K}}}^0n and \uppi \Sigma with a similar mass and the same quantum numbers as the K\textrm{K}^{-}p state. The strengths of these couplings to the K\textrm{K}^{-}p system are of crucial importance for the understanding of the nature of the Λ(1405)\Lambda (1405) resonance and of the attractive K\textrm{K}^{-}p strong interaction. In this article, we present measurements of the K\textrm{K}^{-}p correlation functions in relative momentum space obtained in pp collisions at s = 13\sqrt{s}~=~13 Te, in p–Pb collisions at sNN = 5.02\sqrt{s_{\textrm{NN}}}~=~5.02 Te, and (semi)peripheral Pb–Pb collisions at sNN = 5.02\sqrt{s_{\textrm{NN}}}~=~5.02 Te. The emitting source size, composed of a core radius anchored to the K+\textrm{K}^{+}p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the K0{\overline{\textrm{K}}}^0n and \uppi \Sigma inelastic channels on the measured K\textrm{K}^{-}p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights ω\omega , necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured K\textrm{K}^{-}p interaction indicates that, while the \uppi \Sigma K\textrm{K}^{-}p dynamics is well reproduced by the model, the coupling to the K0{\overline{\textrm{K}}}^0n channel in the model is currently underestimated.The interaction of K\rm{K}^{-} with protons is characterised by the presence of several coupled channels, systems like K0{\rm \overline{K}^0}n and πΣ\pi\Sigma with a similar mass and the same quantum numbers as the K\rm{K}^{-}p state. The strengths of these couplings to the K\rm{K}^{-}p system are of crucial importance for the understanding of the nature of the Λ(1405)\Lambda(1405) resonance and of the attractive K\rm{K}^{-}p strong interaction. In this article, we present measurements of the K\rm{K}^{-}p correlation functions in relative momentum space obtained in pp collisions at s = 13\sqrt{s}~=~13 TeV, in p-Pb collisions at sNN = 5.02\sqrt{s_{\mathrm{NN}}}~=~5.02 TeV, and (semi)peripheral Pb-Pb collisions at sNN = 5.02\sqrt{s_{\mathrm{NN}}}~=~5.02 TeV. The emitting source size, composed of a core radius anchored to the K+\rm{K}^{+}p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the K0{\rm \overline{K}^0}n and πΣ\pi\Sigma inelastic channels on the measured K\rm{K}^{-}p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights ω\omega, necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured K\rm{K}^{-}p interaction indicates that, while the πΣK\pi\Sigma-\rm{K}^{-}p dynamics is well reproduced by the model, the coupling to the K0{\rm \overline{K}^0}n channel in the model is currently underestimated

    Production of Λ\Lambda and KS0{\rm K}^{0}_{\rm S} in jets in p-Pb collisions at sNN=5\sqrt{s_{\rm NN}} = 5 TeV and pp collisions at s=7\sqrt{s} = 7 TeV

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    The production of Λ\Lambda baryons and KS0{\rm K}^{0}_{\rm S} mesons (V0{\rm V}^{0} particles) was measured in p-Pb collisions at sNN=5\sqrt{s_{\rm NN}} = 5 TeV and pp collisions at s=7\sqrt{s} = 7 TeV with ALICE at the LHC. The production of these strange particles is studied separately for particles associated with hard scatterings and the underlying event to shed light on the baryon-to-meson ratio enhancement observed at intermediate transverse momentum (pTp_{\rm T}) in high multiplicity pp and p-Pb collisions. Hard scatterings are selected on an event-by-event basis with jets reconstructed with the anti-kTk_{\rm T} algorithm using charged particles. The production of strange particles associated with jets pT,  jetch>10p_{\rm T,\;jet}^{\rm ch}>10 GeV/cc is reported as a function of pTp_{\rm T} in both systems; and its dependence on pTp_{\rm T} with jets pT,  jetch>20p_{\rm T,\;jet}^{\rm ch}>20 GeV/cc and on angular distance from the jet axis, R(V0,  jet)R({\rm V}^{0},\;{\rm jet}), for jets with pT,  jetch>10p_{\rm T,\;jet}^{\rm ch} > 10 GeV/cc are reported in p-Pb collisions. The results are compared with the strange particle production in the underlying event. The Λ/KS0\Lambda/{\rm K}^{0}_{\rm S} ratio associated with jets in p-Pb collisions for R(V0,  jet)<0.4R({\rm V}^{0},\;{\rm jet})<0.4 is consistent with the ratio measured in pp collisions and with the expectation of jets fragmenting in vacuum given by the PYTHIA event generator
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