1,418 research outputs found

    Brief Mindfulness Meditation Improves Attention In Novices: Evidence From ERPs And Moderation By Neuroticism

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    Past research has found that mindfulness meditation training improves executive attention. Event-related potentials (ERPs) have indicated that this effect could be driven by more efficient allocation of resources on demanding attentional tasks, such as the Flanker Task and the Attention Network Test (ANT). However, it is not clear whether these changes depend on long-term practice. In two studies, we sought to investigate the effects of a brief, 10-min meditation session on attention in novice meditators, compared to a control activity. We also tested moderation by individual differences in neuroticism and the possible underlying neural mechanisms driving these effects, using ERPs. In Study 1, participants randomly assigned to listen to a 10-min meditation tape had better accuracy on incongruent trials on a Flanker task, with no detriment in reaction times (RTs), indicating better allocation of resources. In Study 2, those assigned to listen to a meditation tape performed an ANT more quickly than control participants, with no detriment in performance. Neuroticism moderated both of these effects, and ERPs showed that those individuals lower in neuroticism who meditated for 10 min exhibited a larger N2 to incongruent trials compared to those who listened to a control tape; whereas those individuals higher in neuroticism did not. Together, our results support the hypothesis that even brief meditation improves allocation of attentional resources in some novices

    Impulsive noise removal from color images with morphological filtering

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    This paper deals with impulse noise removal from color images. The proposed noise removal algorithm employs a novel approach with morphological filtering for color image denoising; that is, detection of corrupted pixels and removal of the detected noise by means of morphological filtering. With the help of computer simulation we show that the proposed algorithm can effectively remove impulse noise. The performance of the proposed algorithm is compared in terms of image restoration metrics and processing speed with that of common successful algorithms.Comment: The 6th international conference on analysis of images, social networks, and texts (AIST 2017), 27-29 July, 2017, Moscow, Russi

    Texture and shape of two-dimensional domains of nematic liquid crystal

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    We present a generalized approach to compute the shape and internal structure of two-dimensional nematic domains. By using conformal mappings, we are able to compute the director field for a given domain shape that we choose from a rich class, which includes drops with large and small aspect ratios, and sharp domain tips as well as smooth ones. Results are assembled in a phase diagram that for given domain size, surface tension, anchoring strength, and elastic constant shows the transitions from a homogeneous to a bipolar director field, from circular to elongated droplets, and from sharp to smooth domain tips. We find a previously unaccounted regime, where the drop is nearly circular, the director field bipolar and the tip rounded. We also find that bicircular director fields, with foci that lie outside the domain, provide a remarkably accurate description of the optimal director field for a large range of values of the various shape parameters.Comment: 12 pages, 10 figure

    Geometry-dependent critical currents in superconducting nanocircuits

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    In this paper we calculate the critical currents in thin superconducting strips with sharp right-angle turns, 180-degree turnarounds, and more complicated geometries, where all the line widths are much smaller than the Pearl length Λ=2λ2/d\Lambda = 2 \lambda^2/d. We define the critical current as the current that reduces the Gibbs free-energy barrier to zero. We show that current crowding, which occurs whenever the current rounds a sharp turn, tends to reduce the critical current, but we also show that when the radius of curvature is less than the coherence length this effect is partially compensated by a radius-of-curvature effect. We propose several patterns with rounded corners to avoid critical-current reduction due to current crowding. These results are relevant to superconducting nanowire single-photon detectors, where they suggest a means of improving the bias conditions and reducing dark counts. These results also have relevance to normal-metal nanocircuits, as these patterns can reduce the electrical resistance, electromigration, and hot spots caused by nonuniform heating.Comment: 29 pages, 24 figure

    Targeting Inaccurate Atomic Data in the Eta Car Ejecta Absorption

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    The input from the laboratory spectroscopist community has on many occasions helped the analysis of the eta Car spectrum. Our analysis has targeted spectra where improved wavelengths and oscillator strengths are needed. We will demonstrate how experimentally derived atomic data have improved our spectral analysis, and illuminate where more work still is needed

    3D mappings by generalized joukowski transformations

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    The classical Joukowski transformation plays an important role in di erent applications of conformal mappings, in particular in the study of ows around the so-called Joukowski airfoils. In the 1980s H. Haruki and M. Barran studied generalized Joukowski transformations of higher order in the complex plane from the view point of functional equations. The aim of our contribution is to study the analogue of those generalized Joukowski transformations in Euclidean spaces of arbitrary higher dimension by methods of hypercomplex analysis. They reveal new insights in the use of generalized holomorphic functions as tools for quasi-conformal mappings. The computational experiences focus on 3D-mappings of order 2 and their properties and visualizations for di erent geometric con gurations, but our approach is not restricted neither with respect to the dimension nor to the order.Financial support from "Center for Research and Development in Mathematics and Applications" of the University of Aveiro, through the Portuguese Foundation for Science and Technology (FCT), is gratefully acknowledged. The research of the first author was also supported by the FCT under the fellowship SFRH/BD/44999/2008. Moreover, the authors would like to thank the anonymous referees for their helpful comments and suggestions which improved greatly the final manuscript

    Representation of Quantum Field Theory by Elementary Quantum Information

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    In this paper is considered relativistic quantum field theory expressed by elementary units of quantum information as they are considered as fundamental entity of nature by Carl Friedrich von Weizsaecker. Through quantization of a Weyl spinor describing an elementary unit of quantum information and consisting of four real components one obtains four pairs of creation and annihilation operators acting in a tensor space of states containing many units of quantum information. There can be constructed position and momentum operators from the creation and annihilation operators and based on these operators the Poincare group can be represented in this abstract tensor space of quantum information. A general state in the tensor space can be mapped to a state in Minkowski space-time by using the position representation of the eigenstates of the occupation number operators which correspond to the eigenstates of the harmonic oscillator. This yields a description of relativistic quantum mechanics. Quantization of the coefficients of a general state in the tensor space leads to many particle theory and thus to quantum field theory.Comment: 7 page
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