28,605 research outputs found
Understanding Confinement From Deconfinement
We use effective magnetic SU(N) pure gauge theory with cutoff M and fixed
gauge coupling g_m to calculate non-perturbative magnetic properties of the
deconfined phase of SU(N) Yang-Mills theory. We obtain the response to an
external closed loop of electric current by reinterpreting and regulating the
calculation of the one loop effective potential in Yang-Mills theory. This
effective potential gives rise to a color magnetic charge density, the
counterpart in the deconfined phase of color magnetic currents introduced in
effective dual superconductor theories of the confined phase via magnetically
charged Higgs fields. The resulting spatial Wilson loop has area law behavior.
Using values of M and g_m determined in the confined phase, we find SU(3)
spatial string tensions compatible with lattice simulations in the temperature
interval 1.5T_c < T < 2.5T_c. Use of the effective theory to analyze
experiments on heavy ion collisions will provide applications and further tests
of these ideas.Comment: 18 pages, 5 figures, v2: fixed archive title (only
On the evaluation formula for Jack polynomials with prescribed symmetry
The Jack polynomials with prescribed symmetry are obtained from the
nonsymmetric polynomials via the operations of symmetrization,
antisymmetrization and normalization. After dividing out the corresponding
antisymmetric polynomial of smallest degree, a symmetric polynomial results. Of
interest in applications is the value of the latter polynomial when all the
variables are set equal. Dunkl has obtained this evaluation, making use of a
certain skew symmetric operator. We introduce a simpler operator for this
purpose, thereby obtaining a new derivation of the evaluation formula. An
expansion formula of a certain product in terms of Jack polynomials with
prescribed symmetry implied by the evaluation formula is used to derive a
generalization of a constant term identity due to Macdonald, Kadell and Kaneko.
Although we don't give the details in this work, the operator introduced here
can be defined for any reduced crystallographic root system, and used to
provide an evaluation formula for the corresponding Heckman-Opdam polynomials
with prescribed symmetry.Comment: 18 page
A nonstationary form of the range refraction parabolic equation and its application as an artificial boundary condition for the wave equation in a waveguide
The time-dependent form of Tappert's range refraction parabolic equation is
derived using Daletskiy-Krein formula form noncommutative analysis and proposed
as an artificial boundary condition for the wave equation in a waveguide. The
numerical comparison with Higdon's absorbing boundary conditions shows
sufficiently good quality of the new boundary condition at low computational
cost.Comment: 12 pages, 9 figure
A Novel Method to Prevent Misconfigurations of Industrial Automation and Control Systems
Configuration errors are among the dominant causes of system faults for the industrial automation and control systems (IACS). It is difficult to detect and correct such errors of IACS as there are various kinds of systems and devices with miscellaneous configuration specifications. In this paper, we first propose a streaming algorithm to keep all the configuration changes in the limited memory space. And, when making a new configuration change, another novel streaming algorithm is proposed to search and return all the similar historical changes which can be used to validate this new one. So far, we are the first to model the configuration changes of IACS as a data stream and apply the streaming similarity search in correcting configuration errors while overcoming the inherent unbounded-memory bottleneck. The theoretical correctness and complexity analyses are presented. Experiments with real and synthetic datasets confirm the theoretical analyses and demonstrate the effectiveness of the proposed method in preventing misconfigurations of IACS
Radiation content of Conformally flat initial data
We study the radiation of energy and linear momentum emitted to infinity by
the headon collision of binary black holes, starting from rest at a finite
initial separation, in the extreme mass ratio limit. For these configurations
we identify the radiation produced by the initially conformally flat choice of
the three geometry. This identification suggests that the radiated energy and
momentum of headon collisions will not be dominated by the details of the
initial data for evolution of holes from initial proper separations
. For non-headon orbits, where the amount of radiation is orders of
magnitude larger, the conformally flat initial data may provide a relative even
better approximation.Comment: 4 pages, 4 figure
Antiferromagnetic Order in MnO Spherical Nanoparticles
We have performed unpolarized and polarized neutron diffraction experiments
on monodisperse 8 nm and 13 nm antiferromagnetic MnO nanoparticles. For the 8
nm sample, the antiferromagnetic transition temperature (114 K) is
suppressed compared to the bulk material (119 K) while for the 13 nm sample
(120 K) is comparable to the bulk. The neutron diffraction data of the
nanoparticles is well described using the bulk MnO magnetic structure but with
a substantially reduced average magnetic moment of 4.20.3 /Mn for
the 8 nm sample and 3.90.2 /Mn for the 13 nm sample. An analysis of
the polarized neutron data on both samples shows that in an individual MnO
nanoparticle about 80 of Mn ions order. These results can be explained by a
structure in which the monodisperse nanoparticles studied here have a core that
behaves similar to the bulk with a surface layer which does not contribute
significantly to the magnetic order.Comment: 7 pages, 5 figure
Outflows at the Edges of an Active Region in a Coronal Hole: A Signature of Active Region Expansion?
Outflows of plasma at the edges of active regions surrounded by quiet Sun are
now a common observation with the Hinode satellite. While there is
observational evidence to suggest that the outflows are originating in the
magnetic field surrounding the active regions, there is no conclusive evidence
that reveals how they are driven. Motivated by observations of outflows at the
periphery of a mature active region embedded in a coronal hole, we have used a
three-dimensional simulation to emulate the active region's development in
order to investigate the origin and driver of these outflows. We find outflows
are accelerated from a site in the coronal hole magnetic field immediately
surrounding the active region and are channelled along the coronal hole field
as they rise through the atmosphere. The plasma is accelerated simply as a
result of the active region expanding horizontally as it develops. Many of the
characteristics of the outflows generated in the simulation are consistent with
those of observed outflows: velocities up to 45 km per sec, properties akin to
the coronal hole, proximity to the active region's draining loops, expansion
with height, and projection over monopolar photospheric magnetic
concentrations. Although the horizontal expansion occurs as a consequence of
the active region's development in the simulation, expansion is also a general
feature of established active regions. Hence, it is entirely possible and
plausible that the expansion acceleration mechanism displayed in the simulation
is occurring in active regions on the Sun and, in addition to reconnection, is
driving the outflows observed at their edges.Comment: 19 pages, 9 figure
Effect of Bending Anisotropy on the 3D Conformation of Short DNA Loops
The equilibrium three dimensional shape of relatively short loops of DNA is
studied using an elastic model that takes into account anisotropy in bending
rigidities. Using a reasonable estimate for the anisotropy, it is found that
cyclized DNA with lengths that are not integer multiples of the pitch take on
nontrivial shapes that involve bending out of planes and formation of kinks.
The effect of sequence inhomogeneity on the shape of DNA is addressed, and
shown to enhance the geometrical features. These findings could shed some light
on the role of DNA conformation in protein--DNA interactions
The Galois Complexity of Graph Drawing: Why Numerical Solutions are Ubiquitous for Force-Directed, Spectral, and Circle Packing Drawings
Many well-known graph drawing techniques, including force directed drawings,
spectral graph layouts, multidimensional scaling, and circle packings, have
algebraic formulations. However, practical methods for producing such drawings
ubiquitously use iterative numerical approximations rather than constructing
and then solving algebraic expressions representing their exact solutions. To
explain this phenomenon, we use Galois theory to show that many variants of
these problems have solutions that cannot be expressed by nested radicals or
nested roots of low-degree polynomials. Hence, such solutions cannot be
computed exactly even in extended computational models that include such
operations.Comment: Graph Drawing 201
Collapse of Flux Tubes
The dynamics of an idealized, infinite, MIT-type flux tube is followed in
time as the interior evolves from a pure gluon field to a
plasma. We work in color U(1). pair formation is evaluated
according to the Schwinger mechanism using the results of Brink and Pavel. The
motion of the quarks toward the tube endcaps is calculated by a Boltzmann
equation including collisions. The tube undergoes damped radial oscillations
until the electric field settles down to zero. The electric field stabilizes
the tube against pinch instabilities; when the field vanishes, the tube
disintegrates into mesons. There is only one free parameter in the problem,
namely the initial flux tube radius, to which the results are very sensitive.
Among various quantities calculated is the mean energy of the emitted pions.Comment: 16 pages plus 12 figures. RevTex3. DOE/ER/40427-160N9
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