701 research outputs found
On Abelian Multi-Chern-Simons Field Theories
In this paper a class of multi-Chern-Simons field theories which is relevant
to the statistical mechanics of polymer systems is investigated. Motivated by
the problems which one encounters in the treatment of these theories, a general
procedure is presented to eliminate the Chern-Simons fields from their action.
In this way it has been possible to derive an expression of the partition
function of topologically linked polymers which depends explicitly on the
topological numbers and does not have intractable nonlocal terms as it happened
in previous approaches. The new formulation of multi-Chern-Simons field
theories is then used to remove and clarify some inconsistencies and
ambiguities which apparently affect field theoretical models of topologically
linked polymers. Finally, the limit of disentangled polymers is discussed.Comment: 18 pages, plain LaTe
CELL-LINED, NONWOVEN MICROFIBER SCAFFOLDS AS A BLOOD INTERFACE *
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73137/1/j.1749-6632.1977.tb41787.x.pd
Dynamical Generation of Fermion Mass and Magnetic Field in Three-Dimensional QED with Chern-Simons Term
We study dynamical symmetry breaking in three-dimensional QED with a
Chern-Simons (CS) term, considering the screening effect of flavor
fermions. We find a new phase of the vacuum, in which both the fermion mass and
a magnetic field are dynamically generated, when the coefficient of the CS term
equals . The resultant vacuum becomes the finite-density
state half-filled by fermions. For , we find the fermion
remains massless and only the magnetic field is induced. For ,
spontaneous magnetization does not occur and should be regarded as an external
field.Comment: 8 pages, no figure, to be published in Phys. Rev. Let
Density-functional embedding using a plane-wave basis
The constrained electron density method of embedding a Kohn-Sham system in a
substrate system (first described by P. Cortona, Phys. Rev. B {\bf 44}, 8454
(1991) and T.A. Wesolowski and A. Warshel, J. Phys. Chem {\bf 97}, 8050 (1993))
is applied with a plane-wave basis and both local and non-local
pseudopotentials. This method divides the electron density of the system into
substrate and embedded electron densities, the sum of which is the electron
density of the system of interest. Coupling between the substrate and embedded
systems is achieved via approximate kinetic energy functionals. Bulk aluminium
is examined as a test case for which there is a strong interaction between the
substrate and embedded systems. A number of approximations to the
kinetic-energy functional, both semi-local and non-local, are investigated. It
is found that Kohn-Sham results can be well reproduced using a non-local
kinetic energy functional, with the total energy accurate to better than 0.1 eV
per atom and good agreement between the electron densities.Comment: 11 pages, 4 figure
Thermodynamic properties of spontaneous magnetization in Chern-Simons QED_3
The spontaneous magnetization in Chern-Simons QED_3 is discussed in a finite
temperature system. The thermodynamical potential is analyzed within the weak
field approximation and in the fermion massless limit. We find that there is a
linear term with respect to the magnetic field with a negative coefficient at
any finite temperature. This implies that the spontaneous magnetic field does
not vanish even at high temperature. In addition, we examine the photon
spectrum in the system. We find that the bare Chern-Simons coefficient is
cancelled by the radiative effects. The photons then become topologically
massless according to the magnetization, though they are massive by finite
temperature effects. Thus the magnetic field is a long-range force without the
screening even at high temperature.Comment: 32 pages, Latex, 4 eps figure
Assessment of adipokines, adenine nucleotides and uric acid in the dynamics of coronary intervention
Introduction: The association of vaspin
and visfatin, with a myocardial infarction is still
not fully understood. Reduced levels of adenine
nucleotides are hallmarks of chronic heart failure.
There is little data concerning the relationship
between these markers and their changes over time.
Material/Methods: The concentration of adenine
nucleotides, vaspin and visfatinwere assessed in 41
consecutive patients with acute myocardial infarction one
before (day I) and four days after (day IV) percutaneous
coronary intervention (PCI) and a control group.
Results: Visfatin concentrations were higher before and
after PCI vs. control (visfatin I: median 25.55, 20.12 - 30.69
ng/ml; visfatin IV: median 20.79, 16.89 - 25.61 ng/ml vs.
control: median 14.94, 10.66 - 25.25 ng/ml; p < 0.0001).
Vaspin concentrations were lower before and after PCI vs.
control (vaspin I: median 0.18, 0.11 - 0.44 ng/ml; vaspin IV:
median 0.24, 0.15 - 0.58 ng/ml vs. control: median 1.303,
1.13 - 2.26 ng/ml, p < 0.00001). Concentrations of visfatin, day I, correlated well to vaspin concentrations (r2 = 0.201,
p = 0.011). ATP levels were significantly lower in patients
vs. controls (day I: p = 0.00012; day IV: p = 0.0001).
Conclusions: Changes in the analyzed visfatin and vaspin
concentrations can be used as potential MI markers.
Visfatin serum concentration may be considered a
potential marker to differentiate MI over time
Model-independent X-ray imaging of adsorbed cations at the crystal-water interface.
Abstract We describe an approach to directly image three-dimensional elemental distributions at the crystal-liquid interface with $1 A spatial resolution. This method, based on the Fourier synthesis of X-ray standing wave data, is demonstrated by imaging the distribution of Sr 2þ , Zn 2þ and Y 3þ adsorbed to the rutile (1 1 0)-water interface with no a priori assumptions. The approach resolves distinct sites and is robust for systems with single or multiple simultaneous adsorption sites. The observed ion distributions reveal unexpected differences in the adsorption sites of these cations that are needed to interpret electrical double-layer phenomena using surface complexation models. Published by Elsevier B.V
The Energy Density in the Maxwell-Chern-Simons Theory
A two-dimensional nonrelativistic fermion system coupled to both
electromagnetic gauge fields and Chern-Simons gauge fields is analysed.
Polarization tensors relevant in the quantum Hall effect and anyon
superconductivity are obtained as simple closed integrals and are evaluated
numerically for all momenta and frequencies. The correction to the energy
density is evaluated in the random phase approximation (RPA), by summing an
infinite series of ring diagrams. It is found that the correction has
significant dependence on the particle number density.
In the context of anyon superconductivity, the energy density relative to the
mean field value is minimized at a hole concentration per lattice plaquette
(0.05 \sim 0.06) (p_c a/\hbar)^2 where p_c and a are the momentum cutoff and
lattice constant, respectively. At the minimum the correction is about -5 %
\sim -25 %, depending on the ratio (2m \omega_c)/(p_c^2) where \omega_c is the
frequency cutoff.
In the Jain-Fradkin-Lopez picture of the fractional quantum Hall effect the
RPA correction to the energy density is very large. It diverges logarithmically
as the cutoff is removed, implying that corrections beyond RPA become important
at large momentum and frequency.Comment: 19 pages (plain Tex), 12 figures not included, UMN-TH-1246/9
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