27 research outputs found
Large Loops of Magnetic Current and Confinement in Four Dimensional Lattice Gauge Theory
We calculate the heavy quark potential from the magnetic current due to
monopoles in four dimensional lattice gauge theory. The magnetic current
is found from link angle configurations using the DeGrand-Toussaint
identification method. The link angle configurations are generated in a cosine
action simulation on a lattice. The magnetic current is resolved into
large loops which wrap around the lattice and simple loops which do not.
Wrapping loops are found only in the confined phase. It is shown that the long
range part of the heavy quark potential, in particular the string tension, can
be calculated solely from the large, wrapping loops of magnetic current.Comment: 15 pages (Latex file plus 3 postscript files appended), Univeristy of
Illinois Preprint ILL-(TH)-93-\#1
Phase structure and monopoles in U(1) gauge theory
We investigate the phase structure of pure compact U(1) lattice gauge theory
in 4 dimensions with the Wilson action supplemented by a monopole term. To
overcome the suppression of transitions between the phases in the simulations
we make the monopole coupling a dynamical variable. We determine the phase
diagram and find that the strength of the first order transition decreases with
increasing weight of the monopole term, the transition thus ultimately getting
of second order. After outlining the appropriate topological characterization
of networks of currents lines, we present an analysis of the occurring monopole
currents which shows that the phases are related to topological properties.Comment: 22 pages (latex), 14 figures (available upon request), BU-HEP 94-
Non-Gaussian fixed point in four-dimensional pure compact U(1) gauge theory on the lattice
The line of phase transitions, separating the confinement and the Coulomb
phases in the four-dimensional pure compact U(1) gauge theory with extended
Wilson action, is reconsidered. We present new numerical evidence that a part
of this line, including the original Wilson action, is of second order. By
means of a high precision simulation on homogeneous lattices on a sphere we
find that along this line the scaling behavior is determined by one fixed point
with distinctly non-Gaussian critical exponent nu = 0.365(8). This makes the
existence of a nontrivial and nonasymptotically free four-dimensional pure U(1)
gauge theory in the continuum very probable. The universality and duality
arguments suggest that this conclusion holds also for the monopole loop gas,
for the noncompact abelian Higgs model at large negative squared bare mass, and
for the corresponding effective string theory.Comment: 11 pages, LaTeX, 2 figure
Scaling analysis of the magnetic monopole mass and condensate in the pure U(1) lattice gauge theory
We observe the power law scaling behavior of the monopole mass and condensate
in the pure compact U(1) gauge theory with the Villain action. In the Coulomb
phase the monopole mass scales with the exponent \nu_m=0.49(4). In the
confinement phase the behavior of the monopole condensate is described with
remarkable accuracy by the exponent \beta_{exp}=0.197(3). Possible implications
of these phenomena for a construction of a strongly coupled continuum U(1)
gauge theory are discussed.Comment: Added references [1
Four-dimensional pure compact U(1) gauge theory on a spherical lattice
We investigate the confinement-Coulomb phase transition in the
four-dimensional (4D) pure compact U(1) gauge theory on spherical lattices. The
action contains the Wilson coupling beta and the double charge coupling gamma.
The lattice is obtained from the 4D surface of the 5D cubic lattice by its
radial projection onto a 4D sphere, and made homogeneous by means of
appropriate weight factors for individual plaquette contributions to the
action. On such lattices the two-state signal, impeding the studies of this
theory on toroidal lattices, is absent for gamma le 0. Furthermore, here a
consistent finite-size scaling behavior of several bulk observables is found,
with the correlation length exponent nu in the range nu = 0.35 - 40. These
observables include Fisher zeros, specific-heat and cumulant extrema as well as
pseudocritical values of beta at fixed gamma. The most reliable determination
of nu by means of the Fisher zeros gives nu = 0.365(8). The phase transition at
gamma le 0 is thus very probably of 2nd order and belongs to the universality
class of a non-Gaussian fixed point.Comment: 40 pages, LaTeX, 12 figure
A combination of plasma phospholipid fatty acids and its association with incidence of type 2 diabetes: The EPIC-InterAct case-cohort study.
BACKGROUND: Combinations of multiple fatty acids may influence cardiometabolic risk more than single fatty acids. The association of a combination of fatty acids with incident type 2 diabetes (T2D) has not been evaluated. METHODS AND FINDINGS: We measured plasma phospholipid fatty acids by gas chromatography in 27,296 adults, including 12,132 incident cases of T2D, over the follow-up period between baseline (1991-1998) and 31 December 2007 in 8 European countries in EPIC-InterAct, a nested case-cohort study. The first principal component derived by principal component analysis of 27 individual fatty acids (mole percentage) was the main exposure (subsequently called the fatty acid pattern score [FA-pattern score]). The FA-pattern score was partly characterised by high concentrations of linoleic acid, stearic acid, odd-chain fatty acids, and very-long-chain saturated fatty acids and low concentrations of Îł-linolenic acid, palmitic acid, and long-chain monounsaturated fatty acids, and it explained 16.1% of the overall variability of the 27 fatty acids. Based on country-specific Prentice-weighted Cox regression and random-effects meta-analysis, the FA-pattern score was associated with lower incident T2D. Comparing the top to the bottom fifth of the score, the hazard ratio of incident T2D was 0.23 (95% CI 0.19-0.29) adjusted for potential confounders and 0.37 (95% CI 0.27-0.50) further adjusted for metabolic risk factors. The association changed little after adjustment for individual fatty acids or fatty acid subclasses. In cross-sectional analyses relating the FA-pattern score to metabolic, genetic, and dietary factors, the FA-pattern score was inversely associated with adiposity, triglycerides, liver enzymes, C-reactive protein, a genetic score representing insulin resistance, and dietary intakes of soft drinks and alcohol and was positively associated with high-density-lipoprotein cholesterol and intakes of polyunsaturated fat, dietary fibre, and coffee (p < 0.05 each). Limitations include potential measurement error in the fatty acids and other model covariates and possible residual confounding. CONCLUSIONS: A combination of individual fatty acids, characterised by high concentrations of linoleic acid, odd-chain fatty acids, and very long-chain fatty acids, was associated with lower incidence of T2D. The specific fatty acid pattern may be influenced by metabolic, genetic, and dietary factors
The Many Facets of Sphingolipids in the Specific Phases of Acute Inflammatory Response
This review provides an overview on components of the sphingolipid superfamily, on their localization and metabolism. Information about the sphingolipid biological activity in cell physiopathology is given. Recent studies highlight the role of sphingolipids in inflammatory process. We summarize the emerging data that support the different roles of the sphingolipid members in specific phases of inflammation: (1) migration of immune cells, (2) recognition of exogenous agents, and (3) activation/differentiation of immune cells