259 research outputs found
Real Time Turbulent Video Perfecting by Image Stabilization and Super-Resolution
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)
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
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
A density matrix 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 that may appear in
such a decomposition, for a fixed density matrix . 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
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
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
The identification of problematic meson states as the members of the quark
model nonets by using a hadronic resonance spectrum is discussed.
The results favor the currently adopted assignments for the
axial-vector, tensor, and 1 meson nonets, and suggest a
new assignment for the scalar meson nonet which favors the
interpretation of the and mesons as non-
objects. We also suggest that the 2 state should
be identified with the rather than meson.Comment: Latex, 13 pages plus 8 figure
Statistical Properties of the Linear Sigma Model
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
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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