670 research outputs found

    Pathological regional blood flow in opiate-dependent patients during withdrawal: A HMPAO-SPECT study

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    The aims of the present study were to investigate regional cerebral blood flow (rCBF) in heroin-dependent patients during withdrawal and to assess the relation between these changes and duration of heroin consumption and withdrawal data. The rCBF was measured using brain SPECT with Tc-99m-HMPAO in 16 heroin-dependent patients during heroin withdrawal. Thirteen patients received levomethadone at the time of the SPECT scans. The images were analyzed both visually and quantitatively, a total of 21 hypoperfused brain regions were observed in 11 of the 16 patients. The temporal lobes were the most affected area, hypoperfusions of the right and left temporal lobe were observed in 5 and 5 patients, respectively. Three of the patients had a hypoperfusion of the right frontal lobe, 2 patients showed perfusion defects in the left frontal lobe, right parietal lobe and left parietal lobe. The results of the quantitative assessments of the rCBF were consistent with the results of the qualitative findings. The stepwise regression analysis showed a significant positive correlation (r = 0.54) between the dose of levomethadone at the time of the SPECT scan and the rCBF of the right parietal lobe. Other significant correlations between clinical data and rCBF were not found. The present results suggest brain perfusion abnormalities during heroin withdrawal in heroin-dependent patients, which are not due to the conditions of withdrawal

    Capture4VR: From VR Photography to VR Video

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    Virtual reality (VR) enables the display of dynamic visual content with unparalleled realism and immersion. However, VR is also still a relatively young medium that requires new ways to author content, particularly for visual content that is captured from the real world. This course, therefore, provides a comprehensive overview of the latest progress in bringing photographs and video into VR. Ultimately, the techniques, approaches and systems we discuss aim to faithfully capture the visual appearance and dynamics of the real world, and to bring it into virtual reality to create unparalleled realism and immersion by providing freedom of head motion and motion parallax, which is a vital depth cue for the human visual system. In this half-day course, we take the audience on a journey from VR photography to VR video that began more than a century ago but which has accelerated tremendously in the last five years. We discuss both commercial state-of-the-art systems by Facebook, Google and Microsoft, as well as the latest research techniques and prototypes

    Capture4VR: From VR Photography to VR Video

    Get PDF
    Virtual reality (VR) enables the display of dynamic visual content with unparalleled realism and immersion. However, VR is also still a relatively young medium that requires new ways to author content, particularly for visual content that is captured from the real world. This course, therefore, provides a comprehensive overview of the latest progress in bringing photographs and video into VR. Ultimately, the techniques, approaches and systems we discuss aim to faithfully capture the visual appearance and dynamics of the real world, and to bring it into virtual reality to create unparalleled realism and immersion by providing freedom of head motion and motion parallax, which is a vital depth cue for the human visual system. In this half-day course, we take the audience on a journey from VR photography to VR video that began more than a century ago but which has accelerated tremendously in the last five years. We discuss both commercial state-of-the-art systems by Facebook, Google and Microsoft, as well as the latest research techniques and prototypes

    Phase Behaviour of Amphiphilic Monolayers: Theory and Simulation

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    Coarse grained models of monolayers of amphiphiles (Langmuir monolayers) have been studied theoretically and by computer simulations. We discuss some of the insights obtained with this approach, and present new simulation results which show that idealised models can successfully reproduce essential aspects of the generic phase behaviour of Langmuir monolayers.Comment: To appear in J. Phys.: Cond. Matte

    Infinite-dimensional diffusions as limits of random walks on partitions

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    The present paper originated from our previous study of the problem of harmonic analysis on the infinite symmetric group. This problem leads to a family {P_z} of probability measures, the z-measures, which depend on the complex parameter z. The z-measures live on the Thoma simplex, an infinite-dimensional compact space which is a kind of dual object to the infinite symmetric group. The aim of the paper is to introduce stochastic dynamics related to the z-measures. Namely, we construct a family of diffusion processes in the Toma simplex indexed by the same parameter z. Our diffusions are obtained from certain Markov chains on partitions of natural numbers n in a scaling limit as n goes to infinity. These Markov chains arise in a natural way, due to the approximation of the infinite symmetric group by the increasing chain of the finite symmetric groups. Each z-measure P_z serves as a unique invariant distribution for the corresponding diffusion process, and the process is ergodic with respect to P_z. Moreover, P_z is a symmetrizing measure, so that the process is reversible. We describe the spectrum of its generator and compute the associated (pre)Dirichlet form.Comment: AMSTex, 33 pages. Version 2: minor changes, typos corrected, to appear in Prob. Theor. Rel. Field

    Distance Determination of Variable Galactic Sources

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    We have developed a timing analysis method to determine the distances of variable galactic X-ray sources based on the method advanced by Tr\"{u}mper and Sch\"{o}nfelder in 1973. The light-curve of the halo produced by the scattering of X-rays off the interstellar dust is delayed and smeared by the dust grains. This method utilizes the differences between the power density spectra of the point source and the halo. We present the details of this method and our first applications of this method to the Chandra data of X-ray binary Cyg X-3.Comment: 5 page and 3 figure, The 6th pacific rim conference on steller astrophysics -- a tribute to Helmut A. Ab

    Image-Based Scene Representations for Head-Motion Parallax in 360° Panoramas

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    Creation and delivery of “RealVR” experiences essentially consists of the following four main steps: capture, processing, representation and rendering. In this chapter, we present, compare, and discuss two recent end-to-end approaches, Parallax360 by Luo et al. [9] and MegaParallax by Bertel et al. [3]. Both propose complete pipelines for RealVR content generation and novel-view synthesis with head-motion parallax for 360° environments.Parallax360 uses a robotic arm for capturing thousands of input views on the surface of a sphere. Based on precomputed disparity motion fields and pairwise optical flow, novel viewpoints are synthesized on the fly using flow-based blending of the nearest two to three input views which provides compelling head-motion parallax.MegaParallax proposes a pipeline for RealVR content generation and rendering that emphasizes casual, hand-held capturing. The approach introduces view-dependent flow-based blending to enable novel-view synthesis with head-motion parallax within a viewing area determined by the field of view of the input cameras and the capturing radius.We describe both methods and discuss their similarities and differences in corresponding steps in the RealVR pipeline and show selected results. The chapter ends by discussing advantages and disadvantages as well as outlining the most important limitations and future work.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie SkƂodowska-Curie grant agreement No 66599

    Common variants in FOXP1 are associated with generalized vitiligo

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    In a recent genome-wide association study of generalized vitiligo, we identified ten confirmed susceptibility loci. By testing additional loci that showed suggestive association in the genome-wide study, using two replication cohorts of European descent, we observed replicated association of generalized vitiligo with variants at 3p13 encompassing FOXP1 (rs17008723, combined P = 1.04 × 10−8) and with variants at 6q27 encompassing CCR6 (rs6902119, combined P = 3.94 × 10−7)
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