541 research outputs found

    Neurophysiological vigilance characterisation and assessment: Laboratory and realistic validations involving professional air traffic controllers

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    Vigilance degradation usually causes significant performance decrement. It is also considered the major factor causing the out-of-the-loop phenomenon (OOTL) occurrence. OOTL is strongly related to a high level of automation in operative contexts such as the Air Traffic Management (ATM), and it could lead to a negative impact on the Air Traffic Controllers’ (ATCOs) engagement. As a consequence, being able to monitor the ATCOs’ vigilance would be very important to prevent risky situations. In this context, the present study aimed to characterise and assess the vigilance level by using electroencephalographic (EEG) measures. The first study, involving 13 participants in laboratory settings allowed to find out the neurophysiological features mostly related to vigilance decrements. Those results were also confirmed under realistic ATM settings recruiting 10 professional ATCOs. The results demonstrated that (i) there was a significant performance decrement related to vigilance reduction; (ii) there were no substantial differences between the identified neurophysiological features in controlled and ecological settings, and the EEG-channel configuration defined in laboratory was able to discriminate and classify vigilance changes in ATCOs’ vigilance with high accuracy (up to 84%); (iii) the derived two EEG-channel configuration was able to assess vigilance variations reporting only slight accuracy reduction

    Cortical Cataract and Refractive Error

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    Purpose: To evaluate the relationship between the presence of cortical cataract and accommodation effort, using refractive error as a proxy. Methods: Patients between 50 and 90 years, scheduled for cataract surgery, were selected with the help of a photographic database. Nuclear and cortical cataract were graded and patients grouped having no cataract, pure cortical, mixed or pure nuclear cataract. Refraction data at the time of the photograph was converted to estimated spherical equivalent refractive error each patient would have had at the age of 45 years. Results: From the initial 239 eyes from 239 patients, cases with myopia below –6.5 dpt and hyperopia above 6.5 dpt were excluded, resulting in 199 cases for final analysis. Eyes with no cataract showed the lowest median refractive error (–3.65 dpt), followed by the pure nuclear group (–2.69 dpt). The median refractive error for pure cortical (–0.23 dpt) and mixed cataracts (–0.87 dpt) were close to emmetropia. Cortical cataracts were found in 37% of myopes, 82% of emmetropes, and 85% of hyperopes. Conclusion: Emmetropes and hyperopes tend to develop more cortical cataract than myopes. These cortical cataracts might be caused by shear stress inside the crystalline lens due to accommodation efforts at the time of onset of presbyopia

    Preliminary results using a P300 brain-computer interface speller: a possible interaction effect between presentation paradigm and set of stimuli

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    Fernåndez-Rodríguez Á., Medina-Juliå M.T., Velasco-Álvarez F., Ron-Angevin R. (2019) Preliminary Results Using a P300 Brain-Computer Interface Speller: A Possible Interaction Effect Between Presentation Paradigm and Set of Stimuli. In: Rojas I., Joya G., Catala A. (eds) Advances in Computational Intelligence. IWANN 2019. Lecture Notes in Computer Science, vol 11506. Springer, ChamSeveral proposals to improve the performance controlling a P300-based BCI speller have been studied using the standard row-column presentation (RCP) par-adigm. However, this paradigm could not be suitable for those patients with lack of gaze control. To solve that, the rapid serial visual presentation (RSVP) para-digm, which presents the stimuli located in the same position, has been proposed in previous studies. Thus, the aim of the present work is to assess if a stimuli set of pictures that improves the performance in RCP, could also improve the per-formance in a RSVP paradigm. Six participants have controlled four conditions in a calibration task: letters in RCP, pictures in RCP, letters in RSVP and pictures in RSVP. The results showed that pictures in RCP obtained the best accuracy and information transfer rate. The improvement effect given by pictures was greater in the RCP paradigm than in RSVP. Therefore, the improvements reached under RCP may not be directly transferred to the RSVP.Universidad de Målaga. Campus de Excelencia Internacional Andalucía Tech

    Recognition of Intentional Violations of Active Constraints in Cooperative Manipulation Tasks

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    Active Constraints (ACs) are high-level control algorithms deployed to assist a human operator in man-machine cooperative tasks [1], and define regions within which it is safe for the robot to move and cut [2]. To enhance the performance in cooperative surgical tasks, adaptive constraints have been exploited to optimally adjust the provided level of assistance according to some knowledge of the task, hardware or user. In [3] Hidden Markov Models were used for the run-time detection of the user intention to leave a guidance constraint to circumvent an obstacle. In this work, we present a novel, Neural Network (NN)-based method for the runtime classification of intentional and unintentional violations of ACs, that is trained on either statistical or frequency features from the enforced constraint forces. We investigate which set of parameters yield faster and more reliable classification results, both for guidance and regional constraints

    Multiphase oxidation of alcohols and sulfides with hydrogen peroxide catalyzedby heteropolyacids

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    This work describes the application of a multiphase system for the oxidation of alcohols to ketones or aldehydes, and the selective conversion of sulfides to sulfoxides or sulfones using Keggin-type heteropolyacids and hydrogen peroxide. Benzylic and secondary alcohols were oxidized to ketones or aldehydes at 70 °C in good yield and selectivity. Similarly, sulfides were converted to sulfoxides or sulfones at room temperature with high yields and selectivity

    The cosmology dependence of the concentration-mass-redshift relation

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    The concentrations of dark matter haloes provide crucial information about their internal structure and how it depends on mass and redshift -- the so-called concentration-mass-redshift relation, denoted c(M,z)c(M,z). We present here an extensive study of the cosmology-dependence of c(M,z)c(M,z) that is based on a suite of 72 gravity-only, full N-body simulations in which the following cosmological parameters were varied: σ8\sigma_{8}, ΩM\Omega_{\mathrm{M}}, Ωb\Omega_{\mathrm{b}}, nsn_{\mathrm{s}}, hh, MνM_{\nu}, w0w_{0} and waw_{\mathrm{a}}. We characterize the impact of these parameters on concentrations for different halo masses and redshifts. In agreement with previous works, and for all cosmologies studied, we find that there exists a tight correlation between the characteristic densities of dark matter haloes within their scale radii, r−2r_{-2}, and the critical density of the Universe at a suitably defined formation time. This finding, when combined with excursion set modelling of halo formation histories, allows us to accurately predict the concentrations of dark matter haloes as a function of mass, redshift, and cosmology. We use our simulations to test the reliability of a number of published models for predicting halo concentration and highlight when they succeed or fail to reproduce the cosmological c(M,z)c(M,z) relation.Comment: 11 pages, 9 figure

    Reaction of dialkyl carbonates with alcohols:Defining a scale of the best leaving and entering groups

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    A series of dialkyl and methyl alkyl carbonates has been synthesized and their reactivity investigated. The behavior of preferential leaving and entering groups for the newly synthesized carbonates has been accurately investigated. Both experimental and computational studies agreed that the scale of leaving groups follows the trend: PhCH2O–, MeO– ≥ EtO–, CH3(CH2)2O–, CH3(CH2)7O– > (CH3)2CHO– > (CH3)3CO–. Accordingly, the scale of the entering group has the same trend, with t-butoxide being the worst entering group. A preliminary attempt to rationalize the nucleofugality trends, limited to the (CH3)3CO– and CH3O– groups, has indicated that a likely origin of the observed trends lies in the different entropic contributions and solvation effects

    The effect of thermal treatment on structure and surface composition of PtCo electro-catalysts for application in PEMFCs operating under automotive conditions

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    Ontem, como aqui escrevi, JosÊ Eduardo Moniz, Director-Geral da TVI, fez uma conferência intitulada A Televisão num Mundo Audiovisual em Mudança na UCP. No vídeo, Moniz fala de seis assuntos: 1) televisão generalista e novas plataformas, 2) perfil de oferta para o telespectador, 3) surgimento do quinto canal, 4) três canais de notícias, 5) programação de qualidade, e 6) blocos informativos

    smt: a Matlab structured matrices toolbox

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    We introduce the smt toolbox for Matlab. It implements optimized storage and fast arithmetics for circulant and Toeplitz matrices, and is intended to be transparent to the user and easily extensible. It also provides a set of test matrices, computation of circulant preconditioners, and two fast algorithms for Toeplitz linear systems.Comment: 19 pages, 1 figure, 1 typo corrected in the abstrac
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