259 research outputs found

    Real Time Turbulent Video Perfecting by Image Stabilization and Super-Resolution

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    Image and video quality in Long Range Observation Systems (LOROS) suffer from atmospheric turbulence that causes small neighbourhoods in image frames to chaotically move in different directions and substantially hampers visual analysis of such image and video sequences. The paper presents a real-time algorithm for perfecting turbulence degraded videos by means of stabilization and resolution enhancement. The latter is achieved by exploiting the turbulent motion. The algorithm involves generation of a reference frame and estimation, for each incoming video frame, of a local image displacement map with respect to the reference frame; segmentation of the displacement map into two classes: stationary and moving objects and resolution enhancement of stationary objects, while preserving real motion. Experiments with synthetic and real-life sequences have shown that the enhanced videos, generated in real time, exhibit substantially better resolution and complete stabilization for stationary objects while retaining real motion.Comment: Submitted to The Seventh IASTED International Conference on Visualization, Imaging, and Image Processing (VIIP 2007) August, 2007 Palma de Mallorca, Spai

    Seasonal variation in serum ascorbic acid and serum lipid composition of free-living baboons (Papio ursinus)

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    Two surveys were conducted in the Kruger National Park in which 205 baboons were captured. The first survey was done during late summer and the second during late winter. Serum ascorbic acid, serum cholesterol and serum phospholipids were determined. Baboons of both sexes and various ages were captured. This work was undertaken to establish serum ascorbic acid, serum cholesterol and serum phospholipid values for baboons under free-living conditions. A seasonal variation was found, and the serum ascorbic acid serum cholesterol and serum phospholipid values were significantly higher during winter than during summer.S. Afr. Med. J., 48, 1700 (1974

    Positive Maps Which Are Not Completely Positive

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    The concept of the {\em half density matrix} is proposed. It unifies the quantum states which are described by density matrices and physical processes which are described by completely positive maps. With the help of the half-density-matrix representation of Hermitian linear map, we show that every positive map which is not completely positive is a {\em difference} of two completely positive maps. A necessary and sufficient condition for a positive map which is not completely positive is also presented, which is illustrated by some examples.Comment: 4pages,The Institute of Theoretical Physics, Academia Sinica, Beijing 100080, P.R. Chin

    Probability distributions consistent with a mixed state

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    A density matrix ρ\rho may be represented in many different ways as a mixture of pure states, \rho = \sum_i p_i |\psi_i\ra \la \psi_i|. This paper characterizes the class of probability distributions (pi)(p_i) that may appear in such a decomposition, for a fixed density matrix ρ\rho. Several illustrative applications of this result to quantum mechanics and quantum information theory are given.Comment: 6 pages, submitted to Physical Review

    A Statistical Mechanical Problem in Schwarzschild Spacetime

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    We use Fermi coordinates to calculate the canonical partition function for an ideal gas in a circular geodesic orbit in Schwarzschild spacetime. To test the validity of the results we prove theorems for limiting cases. We recover the Newtonian gas law subject only to tidal forces in the Newtonian limit. Additionally we recover the special relativistic gas law as the radius of the orbit increases to infinity. We also discuss how the method can be extended to the non ideal gas case.Comment: Corrected an equation misprint, added four references, and brief comments on the system's center of mass and the thermodynamic limi

    Quantum Phenomenology for the Disoriented Chiral Condensate

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    We consider the quantum state describing theDisoriented Chiral Condensate (DCC), which may be produced in high energy collisions. We show how a mean field treatment of the quantum equations corresponding to the classical linear sigma model leads to a squeezed state description of the pions emerging from the DCC. We examine various squeezed and coherent state descriptions of those pions with particular attention to charge and number fluctuations. We also study the phenomenology of multiple DCC domains.Comment: 24 pages, PUPT-148

    Hadronic Resonance Spectrum May Help in Resolution of Meson Nonet Enigmas

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    The identification of problematic meson states as the members of the quark model qqˉq\bar{q} nonets by using a hadronic resonance spectrum is discussed. The results favor the currently adopted qqˉq\bar{q} assignments for the axial-vector, tensor, and 1 3F4^3F_4 JPC=4++J^{PC}=4^{++} meson nonets, and suggest a new qqˉq\bar{q} assignment for the scalar meson nonet which favors the interpretation of the f0(980)f_0(980) and f0(1710)f_0(1710) mesons as non-qqˉq\bar{q} objects. We also suggest that the 2 3S1^3S_1 12(1−)\frac{1}{2}(1^{-}) state should be identified with the K∗(1680)K^\ast (1680) rather than K∗(1410)K^\ast (1410) meson.Comment: Latex, 13 pages plus 8 figure

    Statistical Properties of the Linear Sigma Model

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    The statistical equilibrium properties of the linear sigma model are studied, with a view towards characterizing the field configurations employed as initial conditions for numerical simulations of the formation of disoriented chiral condensates in high-energy nuclear collisions. The field is decomposed into its spatial average (the order parameter) and the fluctuations (the quasi- particles) and enclosed in a rectangular box with periodic boundary conditions. The quantized quasi-particle modes are described approximately by Klein-Gordon dispersion relations containing an effective mass that depends on both the temperature and the magnitude of the order parameter. The thermal fluctuations are instrumental in shaping the effective potential governing the order parameter, and the evolution of its statistical distribution with temperature is discussed, as is the behavior of the associated effective masses. As the system is cooled the field fluctuations subside, causing a smooth change from the high-temperature phase in which chiral symmetry is approximately restored towards the normal phase. Of practical interest is the fact that the equilibrium field configurations can be sampled in a simple manner, thus providing a convenient means for specifying the initial conditions in dynamical simulations of the non-equilibrium relaxation of the chiral field. The corresponding correlation function is briefly considered and used to calculate the spectral strength of radiated pions. Finally, by propagating samples of initial configurations by the exact equation of motion, it has been ascertained that the treatment is sufficiently accurate to be of practical utility.Comment: 42 pages total, incl 18 figs using pstricks ([email protected]

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio
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