648 research outputs found
Goodness-of-Fit Tests to study the Gaussianity of the MAXIMA data
Goodness-of-Fit tests, including Smooth ones, are introduced and applied to
detect non-Gaussianity in Cosmic Microwave Background simulations. We study the
power of three different tests: the Shapiro-Francia test (1972), the
uncategorised smooth test developed by Rayner and Best(1990) and the Neyman's
Smooth Goodness-of-fit test for composite hypotheses (Thomas and Pierce 1979).
The Smooth Goodness-of-Fit tests are designed to be sensitive to the presence
of ``smooth'' deviations from a given distribution. We study the power of these
tests based on the discrimination between Gaussian and non-Gaussian
simulations. Non-Gaussian cases are simulated using the Edgeworth expansion and
assuming pixel-to-pixel independence. Results show these tests behave similarly
and are more powerful than tests directly based on cumulants of order 3, 4, 5
and 6. We have applied these tests to the released MAXIMA data. The applied
tests are built to be powerful against detecting deviations from univariate
Gaussianity. The Cholesky matrix corresponding to signal (based on an assumed
cosmological model) plus noise is used to decorrelate the observations previous
to the analysis. Results indicate that the MAXIMA data are compatible with
Gaussianity.Comment: MNRAS, in pres
E-Flow: A communication system for user notification in dynamic evacuation scenarios
Most of the current evacuation plans are based on static signaling, fixed monitoring infrastructure, and limited user notification and feedback mechanisms. These facts lead to lower situation awareness, in the case event of an emergency, such as blocked emergency exits, while delaying the reaction time of individuals. In this context, we introduce the E-Flow communication system, which improves the user awareness by integrating personal, mobile and fixed devices with the existing monitoring infrastructure. Our system broadens the notification and monitoring alternatives, in real time, among, safety staff, end-users and evacuation related devices, such as sensors and actuators
Role of Initial Data in Higher Dimensional Quasi-Spherical Gravitational Collapse
We study the gravitational collapse in ()-D quasi-spherical Szekeres
space-time (which possess no killing vectors) with dust as the matter
distribution. Instead of choosing the radial coordinate `' as the initial
value for the scale factor , we consider a power function of as the
initial scale for the radius . We examine the influence of initial data on
the formation of singularity in gravitational collapse.Comment: 7 Latex Pages, RevTex Style, No figure
Experimental indication on chiral symmetry restoration in meson spectrum
The spectroscopic predictions of the Ademollo-Veneziano-Weinberg dual model
are critically tested in view of the modern experimental data. The predicted
equidistance of masses squared for chiral partners is shown to be violated high
in energies, instead one observes an approximate degeneracy of these
quantities. This phenomenon can be interpreted as the restoration of
Wigner-Weyl realization of chiral symmetry for highly excited states. The scale
of complete restoration is expected to be 2.5 GeV. A multispin-parity cluster
structure of meson spectrum is revealed.Comment: To be published in Phys. Lett. B, 10 pages, 1 figure, some comments
and references are adde
Nonlinear Dynamical Stability of Newtonian Rotating White Dwarfs and Supermassive Stars
We prove general nonlinear stability and existence theorems for rotating star
solutions which are axi-symmetric steady-state solutions of the compressible
isentropic Euler-Poisson equations in 3 spatial dimensions. We apply our
results to rotating and non-rotating white dwarf, and rotating high density
supermassive (extreme relativistic) stars, stars which are in convective
equilibrium and have uniform chemical composition. This paper is a continuation
of our earlier work ([28])
Gravitation and inertia; a rearrangement of vacuum in gravity
We address the gravitation and inertia in the framework of 'general gauge
principle', which accounts for 'gravitation gauge group' generated by hidden
local internal symmetry implemented on the flat space. We connect this group to
nonlinear realization of the Lie group of 'distortion' of local internal
properties of six-dimensional flat space, which is assumed as a toy model
underlying four-dimensional Minkowski space. The agreement between proposed
gravitational theory and available observational verifications is satisfactory.
We construct relativistic field theory of inertia and derive the relativistic
law of inertia. This theory furnishes justification for introduction of the
Principle of Equivalence. We address the rearrangement of vacuum state in
gravity resulting from these ideas.Comment: 17 pages, no figures, revtex4, Accepted for publication in Astrophys.
Space Sc
Tailoring Anderson localization by disorder correlations in 1D speckle potentials
We study Anderson localization of single particles in continuous, correlated,
one-dimensional disordered potentials. We show that tailored correlations can
completely change the energy-dependence of the localization length. By
considering two suitable models of disorder, we explicitly show that disorder
correlations can lead to a nonmonotonic behavior of the localization length
versus energy. Numerical calculations performed within the transfer-matrix
approach and analytical calculations performed within the phase formalism up to
order three show excellent agreement and demonstrate the effect. We finally
show how the nonmonotonic behavior of the localization length with energy can
be observed using expanding ultracold-atom gases
Generalizations of normal ordering and applications to quantization in classical backgrounds
A nonlocal method of extracting the positive (or the negative) frequency part
of a field, based on knowledge of a 2-point function, leads to certain natural
generalizations of the normal ordering of quantum fields in classical
gravitational and electromagnetic backgrounds and illuminates the origin of the
recently discovered nonlocalities related to a local description of particles.
A local description of particle creation by gravitational backgrounds is given,
with emphasis on the case of black-hole evaporation. The formalism reveals a
previously hidden relation between various definitions of the particle current
and those of the energy-momentum tensor. The implications to particle creation
by classical backgrounds, as well as to the relation between vacuum energy,
dark matter, and cosmological constant, are discussed.Comment: 17 pages, revised, title shortened, to appear in Gen. Rel. Gra
The number of eigenstates: counting function and heat kernel
The main aim of this paper is twofold: (1) revealing a relation between the
counting function N(lambda) (the number of the eigenstates with eigenvalue
smaller than a given number) and the heat kernel K(t), which is still an open
problem in mathematics, and (2) introducing an approach for the calculation of
N(lambda), for there is no effective method for calculating N(lambda) beyond
leading order. We suggest a new expression of N(lambda) which is more suitable
for practical calculations. A renormalization procedure is constructed for
removing the divergences which appear when obtaining N(lambda) from a
nonuniformly convergent expansion of K(t). We calculate N(lambda) for
D-dimensional boxes, three-dimensional balls, and two-dimensional
multiply-connected irregular regions. By the Gauss-Bonnet theorem, we
generalize the simply-connected heat kernel to the multiply-connected case;
this result proves Kac's conjecture on the two-dimensional multiply-connected
heat kernel. The approaches for calculating eigenvalue spectra and state
densities from N(lambda) are introduced.Comment: 17 pages, 1 figure. v2: Equivalent forms of Eqs. (4.8) and (9.2) are
adde
Charged BTZ-like Black Holes in Higher Dimensions
Motivated by many worthwhile paper about (2 + 1)-dimensional BTZ black holes,
we generalize them to to (n + 1)-dimensional solutions, so called BTZ-like
solutions. We show that the electric field of BTZ-like solutions is the same as
(2 + 1)-dimensional BTZ black holes, and also their lapse functions are
approximately the same, too. By these similarities, it is also interesting to
investigate the geometric and thermodynamics properties of the BTZ-like
solutions. We find that, depending on the metric parameters, the BTZ-like
solutions may be interpreted as black hole solutions with inner (Cauchy) and
outer (event) horizons, an extreme black hole or naked singularity. Then, we
calculate thermodynamics quantities and conserved quantities, and show that
they satisfy the first law of thermodynamics. Finally, we perform a stability
analysis in the canonical ensemble and show that the BTZ-like solutions are
stable in the whole phase space.Comment: 5 pages, two column format, one figur
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