2,677 research outputs found
Natural entropy fluctuations discriminate similar looking electric signals emitted from systems of different dynamics
Complexity measures are introduced, that quantify the change of the natural
entropy fluctuations at different length scales in time-series emitted from
systems operating far from equilibrium. They identify impending sudden cardiac
death (SD) by analyzing fifteen minutes electrocardiograms, and comparing to
those of truly healthy humans (H). These measures seem to be complementary to
the ones suggested recently [Phys. Rev. E {\bf 70}, 011106 (2004)] and
altogether enable the classification of individuals into three categories: H,
heart disease patients and SD. All the SD individuals, who exhibit critical
dynamics, result in a common behavior.Comment: Published in Physical Review
Galilean and Dynamical Invariance of Entanglement in Particle Scattering
Particle systems admit a variety of tensor product structures (TPSs)
depending on the algebra of observables chosen for analysis. Global symmetry
transformations and dynamical transformations may be resolved into local
unitary operators with respect to certain TPSs and not with respect to others.
Symmetry-invariant and dynamical-invariant TPSs are defined and various notions
of entanglement are considered for scattering states.Comment: 4 pages, no figures; v.3 has typos corrected, a new reference, and a
revised conclusio
Entropy in the natural time-domain
A surrogate data analysis is presented, which is based on the fluctuations of
the ``entropy'' defined in the natural time-domain [Phys. Rev. E {\bf 68},
031106, 2003]. This entropy is not a static one as, for example, the Shannon
entropy. The analysis is applied to three types of time-series, i.e., seismic
electric signals, ``artificial'' noises and electrocardiograms, and
``recognizes'' the non-Markovianity in all these signals. Furthermore, it
differentiates the electrocardiograms of healthy humans from those of the
sudden cardiac death ones. If and denote the
standard deviation when calculating the entropy by means of a time-window
sweeping through the original data and the ``shuffled'' (randomized) data,
respectively, it seems that the ratio plays a
key-role. The physical meaning of is investigated.Comment: Published in Physical Review
How to reconcile the Rosenbluth and the polarization transfer method in the measurement of the proton form factors
The apparent discrepancy between the Rosenbluth and the polarization transfer
method for the ratio of the electric to magnetic proton form factors can be
explained by a two-photon exchange correction which does not destroy the
linearity of the Rosenbluth plot. Though intrinsically small, of the order of a
few percent of the cross section, this correction is kinematically enhanced in
the Rosenbluth method while it is small for the polarization transfer method,
at least in the range of (Q^2) where it has been used until now.Comment: 4 pages, 4 figures. Version accepted for publication in Phys. Rev.
Let
Stress-energy tensor for a quantised bulk scalar field in the Randall-Sundrum brane model
We calculate the vacuum expectation value of the stress-energy tensor for a
quantised bulk scalar field in the Randall-Sundrum model, and discuss the
consequences of its local behaviour for the self-consistency of the model. We
find that, in general, the stress-energy tensor diverges in the vicinity of the
branes. Our main conclusion is that the stress-energy tensor is sufficiently
complicated that it has implications for the effective potential, or radion
stabilisation, methods that have so far been used.Comment: 16 pages, 3 figures. Minor changes made and references added. To
appear in Phys. Rev.
Post-Newtonian corrections to the motion of spinning bodies in NRGR
In this paper we include spin and multipole moment effects in the formalism
used to describe the motion of extended objects recently introduced in
hep-th/0409156. A suitable description for spinning bodies is developed and
spin-orbit, spin-spin and quadrupole-spin Hamiltonians are found at leading
order. The existence of tidal, as well as self induced finite size effects is
shown, and the contribution to the Hamiltonian is calculated in the latter. It
is shown that tidal deformations start formally at O(v^6) and O(v^10) for
maximally rotating general and compact objects respectively, whereas self
induced effects can show up at leading order. Agreement is found for the cases
where the results are known.Comment: 18 pages, 9 figures. Typos corrected, to appear in Physical Review
B\Bbar mixing with the bulk fields in the Randall-Sundrum model
We calculate the B\Bbar mixing in the Randall-Sundrum bulk model. In this
model, all the Standard Model fields except the Higgs can reside in the bulk.
Two suggestive models of "mixed" and "relaxed" scenarios are considered. We
find that the enhancement of the loop function is 0.51% for the "relaxed" and
1.07% for the "mixed" scenario when the first 4th KK modes are included, for a
bulk fermion mass parameter .Comment: REVTEX, 20 pages, 3 figure
Quantum superposition principle and gravitational collapse: Scattering times for spherical shells
A quantum theory of spherically symmetric thin shells of null dust and their
gravitational field is studied. In Nucl. Phys. 603 (2001) 515 (hep-th/0007005),
it has been shown how superpositions of quantum states with different
geometries can lead to a solution of the singularity problem and black hole
information paradox: the shells bounce and re-expand and the evolution is
unitary. The corresponding scattering times will be defined in the present
paper. To this aim, a spherical mirror of radius R_m is introduced. The
classical formula for scattering times of the shell reflected from the mirror
is extended to quantum theory. The scattering times and their spreads are
calculated. They have a regular limit for R_m\to 0 and they reveal a resonance
at E_m = c^4R_m/2G. Except for the resonance, they are roughly of the order of
the time the light needs to cross the flat space distance between the observer
and the mirror. Some ideas are discussed of how the construction of the quantum
theory could be changed so that the scattering times become considerably
longer.Comment: 30 pages and 5 figures; the post-referee version: shortened and some
formulations improved; to be published in Physical Revie
Memory beyond memory in heart beating: an efficient way to detect pathological conditions
We study the long-range correlations of heartbeat fluctuations with the
method of diffusion entropy. We show that this method of analysis yields a
scaling parameter that apparently conflicts with the direct evaluation
of the distribution of times of sojourn in states with a given heartbeat
frequency. The strength of the memory responsible for this discrepancy is given
by a parameter , which is derived from real data. The
distribution of patients in the (, )-plane yields a neat
separation of the healthy from the congestive heart failure subjects.Comment: submitted to Physical Review Letters, 5 figure
- …