12,450 research outputs found
Discrimination and visualization of ELM types based on a probabilistic description of inter-ELM waiting times
Discrimination and visualization of different observed classes of edge-localized plasma instabilities (ELMs), using advanced data analysis techniques has been considered. An automated ELM type classifier which effectively incorporates measurement uncertainties is developed herein and applied to the discrimination of type I and type III ELMs in a set of carbon-wall JET plasmas. The approach involves constructing probability density functions (PDFs) for inter-ELM waiting times and global plasma parameters and then utilizing an effective similarity measure for comparing distributions: the Rao geodesic distance (GD). It is demonstrated that complete probability distributions of plasma parameters contain significantly more information than the measurement values alone, enabling effective discrimination of ELM type
Topological interactions in systems of mutually interlinked polymer rings
The topological interaction arising in interlinked polymeric rings such as
DNA catenanes is considered. More specifically, the free energy for a pair of
linked random walk rings is derived where the distance between two segments
each of which is part of a different ring is kept constant. The topology
conservation is imposed by the Gauss invariant. A previous approach (M.Otto,
T.A. Vilgis, Phys.Rev.Lett. {\bf 80}, 881 (1998)) to the problem is refined in
several ways. It is confirmed, that asymptotically, i.e. for large
where is average size of single random walk ring, the effective
topological interaction (free energy) scales .Comment: 16 pages, 3 figur
Physics of Quantum Relativity through a Linear Realization
The idea of quantum relativity as a generalized, or rather deformed, version
of Einstein (special) relativity has been taking shape in recent years.
Following the perspective of deformations, while staying within the framework
of Lie algebra, we implement explicitly a simple linear realization of the
relativity symmetry, and explore systematically the resulting physical
interpretations. Some suggestions we make may sound radical, but are arguably
natural within the context of our formulation. Our work may provide a new
perspective on the subject matter, complementary to the previous approach(es),
and may lead to a better understanding of the physics.Comment: 27 pages in Revtex, no figure; proof-edited version to appear in
Phys.Rev.
On the scaling behaviour of cross-tie domain wall structures in patterned NiFe elements
The cross-tie domain wall structure in micrometre and sub-micrometre wide
patterned elements of NiFe, and a thickness range of 30 to 70nm, has been
studied by Lorentz microscopy. Whilst the basic geometry of the cross-tie
repeat units remains unchanged, their density increases when the cross-tie
length is constrained to be smaller than the value associated with a continuous
film. This occurs when element widths are sufficiently narrow or when the wall
is forced to move close to an edge under the action of an applied field. To a
very good approximation the cross-tie density scales with the inverse of the
distance between the main wall and the element edge. The experiments show that
in confined structures, the wall constantly modifies its form and that the need
to generate, and subsequently annihilate, extra vortex/anti-vortex pairs
constitutes an additional source of hysteresis.Comment: 4 pages, 5 figures, accepted for publication in Europhysics Letters
(EPL
The stability in the most external region of the Oort Cloud: The evolution of the ejected comets
In this paper, we present a study about the dynamical effects of the Galaxy
on the external region of the Oort Cloud. The aims of this paper are: i) to
determine an outer limit for the Oort Cloud; and ii) to analyse the dynamical
behaviour of the most external objects of the Cloud and how they are ejected
from the Solar System. This is undertaken by following the temporal evolution
of massless test particles in the Galactic environment of the solar
neighbourhood. Here we show that the effect of the perturbations from the
Galactic tide in the particles is similar to that find for the evolution of
wide binary stars population. Moreover, in the Oort Cloud we found a dynamical
structure around 10 5 au conformed by objects unbound of the Sun. This
structure allows us to define a transition region of stability and an outer
boundary for the Oort Cloud, and it is also in agreement with previous results
about the disruption of wide binary stars.Comment: Accepted for publishing in MNRAS. 13 pages, 9 figures, 2 table
Analytic approach to the evolutionary effects of genetic exchange
We present an approximate analytic study of our previously introduced model
of evolution including the effects of genetic exchange. This model is motivated
by the process of bacterial transformation. We solve for the velocity, the rate
of increase of fitness, as a function of the fixed population size, . We
find the velocity increases with , eventually saturated at an which
depends on the strength of the recombination process. The analytical treatment
is seen to agree well with direct numerical simulations of our model equations
Knuth-Bendix algorithm and the conjugacy problems in monoids
We present an algorithmic approach to the conjugacy problems in monoids,
using rewriting systems. We extend the classical theory of rewriting developed
by Knuth and Bendix to a rewriting that takes into account the cyclic
conjugates.Comment: This is a new version of the paper 'The conjugacy problems in monoids
and semigroups'. This version will appear in the journal 'Semigroup forum
Generalised Einstein Relation for Hot Brownian Motion
The Brownian motion of a hot nanoparticle is described by an effective Markov
theory based on fluctuating hydrodynamics. Its predictions are scrutinized over
a wide temperature range using large-scale molecular dynamics simulations of a
hot nanoparticle in a Lennard-Jones fluid. The particle positions and momenta
are found to be Boltzmann distributed according to distinct effective
temperatures and . For we
derive a formally exact theoretical prediction and establish a generalised
Einstein relation that links it to directly measurable quantities
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