450 research outputs found
Classical String Solutions in Effective Infrared Theory of SU(3) Gluodynamics
We investigate string solutions to the classical equations of motion
("classical QCD strings") for a dual Ginzburg-Landau model corresponding to
SU(3) gluodynamics in an abelian projection. For a certain relation between
couplings of the model the string solutions are defined by first order
differential equations. These solutions are related to vortex configurations of
the Abelian Higgs model in the Bogomol'ny limit. An analytic expression for the
string tension is derived and the string-string interactions are discussed. Our
results imply that the vacuum of SU(3) gluodynamics is near a border between
type-I and type-II dual superconductivity.Comment: 7 pages, LaTeX2e; v2: references added and typos correcte
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Integrated radwaste treatment system lessons learned from 2{1/2} years of operation
The Integrated Radwaste Treatment System (IRTS) at the West Valley Demonstration Project (WVDP) is a pretreatment scheme to reduce the amount of salts in the high-level radioactive waste (vitrification) stream. Following removal of cesium-137 (Cs-137) by ion-exchange in the Supernatant Treatment System (STS), the radioactive waste liquid is volume-reduced by evaporation. Trace amounts of Cs-137 in the resulting distillate are removed by ion-exchange, then the distillate is discharged to the existing plant water treatment system. The concentrated product, 37 to 41 percent solids by weight, is encapsulated in cement producing a stable, low-level waste form. The Integrated Radwaste Treatment System (IRTS) operated in this mode from May 1988 through November 1990, decontaminating 450,000 gallons of high-level waste liquid; evaporating and encapsulating the resulting concentrates into 10,393 71-gallon square drums. A number of process changes and variations from the original operating plan were required to increase the system flow rate and minimize waste volumes. This report provides a summary of work performed to operate the IRTS, including system descriptions, process highlights, and lessons learned
Heavy monopole potential in gluodynamics
We discuss predictions for the interaction energy of the fundamental
monopoles in gluodynamics introduced via the 't Hooft loop. At short distances,
the heavy monopole potential is calculable from first principles. At larger
distances, we apply the Abelian dominance models. We discuss the measurements
which would be crucial to distinguish between various models. Non-zero
temperatures are also considered. Our predictions are in qualitative agreement
with the existing lattice data. We discuss further measurements which would be
crucial to check the model.Comment: 3 pages, 1 figure, Lattice2001(confinement
Short Strings and Gluon Propagator in the Infrared Region
We discuss how infrared region influence on short distance physics via new
object, called ``short string''. This object exists in confining theories and
violates the operator product expansion. Most analytical results are obtained
for the dual Abelian Higgs theory, while phenomenological arguments are given
for QCD.Comment: LATTICE99(confine) - 6 page
Gluodynamics in external field in dual superconductor approach
We show that gluodynamics in an external Abelian electromagnetic field should
possess a deconfining phase transition at zero temperature. Our analytical
estimation of the critical external field is based on the dual superconductor
picture which is formulated in the Euclidean space suitable for lattice
calculations. A dual superconductor model corresponding to the SU(2)
gluodynamics possesses confinement and deconfinement phases below and,
respectively, above the critical field. A dual superconductor model for the
SU(3) gauge theory predicts a rich phase structure containing confinement,
asymmetric confinement and deconfinement phases. The quark bound states in
these phases are analyzed. Inside the baryon the strings are Y--shaped as
predicted by the dual superconductor picture. This shape is geometrically
asymmetric in the asymmetric confinement phases. The results of the paper can
be used to check the dual superconductor mechanism in gluodynamics.Comment: 11 pages, 2 figures, LaTeX2e; v2: minor corrections, to be published
in Phys.Lett.
Assessing adherence to Antihypertensive therapy in primary health care in Namibia: findings and implications
Namibia has the highest burden and incidence of hypertension in sub-Sahara Africa. Though non-adherence to antihypertensive therapy is an important cardiovascular risk factor, little is known about potential ways to improve adherence in Namibia following universal access. The objective of this study is to validate the Hill-Bone compliance scale and determine the level and predictors of adherence to antihypertensive treatment in primary health care settings in sub-urban townships of Windhoek, Namibia
Towards Abelian-like formulation of the dual gluodynamics
We consider gluodynamics in case when both color and magnetic charges are
present. We discuss first short distance physics, where only the fundamental
|Q|=1 monopoles introduced via the `t Hooft loop can be considered
consistently. We show that at short distances the external monopoles interact
as pure Abelian objects. This result can be reproduced by a Zwanziger-type
Lagrangian with an Abelian dual gluon. We introduce also an effective dual
gluodynamics which might be a valid approximation at distances where the
monopoles |Q|=2 can be considered as point-like as well. Assuming the monopole
condensation we arrive at a model which is reminiscent in some respect of the
Abelian Higgs model but, unlike the latter leaves space for the Casimir
scaling.Comment: 28+1 pp., Latex2e, 1 figur
Tricritical Behavior of Two-Dimensional Scalar Field Theories
We compute by Monte Carlo numerical simulations the critical exponents of
two-dimensional scalar field theories at the tricritical point.
The results are in agreement with the Zamolodchikov conjecture based on
conformal invariance.Comment: 13 pages, uuencode tar-compressed Postscript file, preprint numbers:
IF/UFRJ/25/94, DFTUZ 94.06 and NYU--TH--94/10/0
Weak convergence of finite element approximations of linear stochastic evolution equations with additive noise II. Fully discrete schemes
We present an abstract framework for analyzing the weak error of fully
discrete approximation schemes for linear evolution equations driven by
additive Gaussian noise. First, an abstract representation formula is derived
for sufficiently smooth test functions. The formula is then applied to the wave
equation, where the spatial approximation is done via the standard continuous
finite element method and the time discretization via an I-stable rational
approximation to the exponential function. It is found that the rate of weak
convergence is twice that of strong convergence. Furthermore, in contrast to
the parabolic case, higher order schemes in time, such as the Crank-Nicolson
scheme, are worthwhile to use if the solution is not very regular. Finally we
apply the theory to parabolic equations and detail a weak error estimate for
the linearized Cahn-Hilliard-Cook equation as well as comment on the stochastic
heat equation
An integral method for solving nonlinear eigenvalue problems
We propose a numerical method for computing all eigenvalues (and the
corresponding eigenvectors) of a nonlinear holomorphic eigenvalue problem that
lie within a given contour in the complex plane. The method uses complex
integrals of the resolvent operator, applied to at least column vectors,
where is the number of eigenvalues inside the contour. The theorem of
Keldysh is employed to show that the original nonlinear eigenvalue problem
reduces to a linear eigenvalue problem of dimension .
No initial approximations of eigenvalues and eigenvectors are needed. The
method is particularly suitable for moderately large eigenvalue problems where
is much smaller than the matrix dimension. We also give an extension of the
method to the case where is larger than the matrix dimension. The
quadrature errors caused by the trapezoid sum are discussed for the case of
analytic closed contours. Using well known techniques it is shown that the
error decays exponentially with an exponent given by the product of the number
of quadrature points and the minimal distance of the eigenvalues to the
contour
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