321 research outputs found
Critical slowing down of topological modes
We investigate the critical slowing down of the topological modes using local
updating algorithms in lattice 2-d CP^(N-1) models. We show that the
topological modes experience a critical slowing down that is much more severe
than the one of the quasi-Gaussian modes relevant to the magnetic
susceptibility, which is characterized by with
. We argue that this may be a general feature of Monte Carlo
simulations of lattice theories with non-trivial topological properties, such
as QCD, as also suggested by recent Monte Carlo simulations of 4-d SU(N)
lattice gauge theories.Comment: 16 pages, 4 figure
B decays on the lattice
I review recent developments in lattice calculations of B decay matrix
elements and other related quantities.Comment: LATTICE99(plenary), 12 pages, 7 postscript figures, uses espcrc2.sty,
references are update
Correlates and outcomes of posttransplant smoking in solid organ transplant recipients : a systematic literature review and meta-analysis
Despite smoking being an absolute or relative contraindication for transplantation, about 11% to 40% of all patients continue or resume smoking posttransplant. This systematic review with meta-analysis investigated the correlates and outcomes associated with smoking after solid organ transplantation.; We searched PubMed, EMBASE, CINAHL, and PsycINFO from inception until January 2016, using state-of-the art methodology. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were computed for correlates/outcomes investigated 5 times or more.; Seventy-three studies (43 in kidney, 17 in heart, 12 in liver, 1 in lung transplantation) investigated 95 correlates and 24 outcomes, of which 6 correlates and 4 outcomes could be included in the meta-analysis. The odds of smoking posttransplant were 1.33 times higher in men (95% CI, 1.12-1.57). Older individuals were significantly less likely to smoke (OR, 0.48; 95% CI, 0.38-0.62), as were patients with a higher body mass index (OR, 0.68; 95% CI, 0.52-0.89). Hypertension (OR, 1.16; 95% CI, 0.77-1.75), diabetes mellitus (OR, 0.52; 95% CI, 0.15-1.78), and having a history of cardiovascular disease (OR, 0.92; 95% CI, 0.77-1.09) were not significant correlates. Posttransplant smokers had higher odds of newly developed posttransplant cardiovascular disease (OR, 1.41; 95% CI, 1.02-1.95), nonskin malignancies (OR, 2.58; 95% CI, 1.26-5.29), a shorter patient survival time (OR, 0.59; 95% CI, 0.44-0.79), and higher odds of mortality (OR, 1.74; 95% CI, 1.21-2.48).; Posttransplant smoking is associated with poor outcomes. Our results might help clinicians to understand which patients are more likely to smoke posttransplant, guide interventional approaches, and provide recommendations for future research
String Breaking as a Mixing Phenomenon in the SU(2) Higgs Model
We study the potential of a static quark anti-quark pair in the confinement
``phase'' of the SU(2) Higgs model. Around separation r_b, the confining string
of the gauge field breaks by formation of a dynamical pair of light quarks. The
ground state and first excited state static potentials are determined by a
variational technique from a matrix correlation in which suitably smeared gauge
and Higgs fields enter. Our results at beta=2.4 clearly show string breaking
(r_b ~ 1.9r_0). The investigation of properly defined overlaps confirms the
interpretation of string breaking as a level crossing phenomenon between
string-type and meson-type states. We study the scaling properties of the
static potentials along a line of constant physics, varying the lattice spacing
by a factor of 2. Our results show compatibility with scaling within tiny
errors.Comment: 21 pages, 9 figure
Quenched divergences in the deconfined phase of SU(2) gauge theory
The spectrum of the overlap Dirac operator in the deconfined phase of
quenched gauge theory is known to have three parts: exact zeros arising from
topology, small nonzero eigenvalues that result in a non-zero chiral
condensate, and the dense bulk of the spectrum, which is separated from the
small eigenvalues by a gap. In this paper, we focus on the small nonzero
eigenvalues in an SU(2) gauge field background at and . This
low-lying spectrum is computed on four different spatial lattices (,
, , and ). As the volume increases, the small eigenvalues
become increasingly concentrated near zero in such a way as to strongly suggest
that the infinite volume condensate diverges.Comment: 12 pages, 3 figures, version to appear in Physical Review
Management of Proximal Phalangeal Fractures of the Hand Using Finger Nail Traction and a Digital Splint: A Prospective Study of 43 Cases
Order a improved renormalization constants
We present non-perturbative results for the constants needed for on-shell
improvement of bilinear operators composed of Wilson fermions. We work
at and 6.2 in the quenched approximation. The calculation is done
by imposing axial and vector Ward identities on correlators similar to those
used in standard hadron mass calculations. A crucial feature of the calculation
is the use of non-degenerate quarks. We also obtain results for the constants
needed for off-shell improvement of bilinears, and for the scale and
scheme independent renormalization constants, (Z_A), (Z_V) and (Z_S/Z_P).
Several of the constants are determined using a variety of different Ward
identities, and we compare their relative efficacies. In this way, we find a
method for calculating that gives smaller errors than that used
previously. Wherever possible, we compare our results with those of the ALPHA
collaboration (who use the Schr\"odinger functional) and with 1-loop
tadpole-improved perturbation theory.Comment: 48 pages. Modified "axis" source for figures also included. Typos
corrected (version published in Phys. Rev. D
The Schwinger Model with Perfect Staggered Fermions
We construct and test a quasi-perfect lattice action for staggered fermions.
The construction starts from free fermions, where we suggest a new blocking
scheme, which leads to excellent locality of the perfect action. An adequate
truncation preserves a high quality of the free action. An Abelian gauge field
is inserted in d=2 by effectively tuning the couplings to a few short-ranged
lattice paths, based on the behavior of topological zero modes. We simulate the
Schwinger model with this action, applying a new variant of Hybrid Monte Carlo,
which damps the computational overhead due to the non-standard couplings. We
obtain a tiny ``pion'' mass down to very small \beta, while the ``\eta'' mass
follows very closely the prediction of asymptotic scaling. The observation that
even short-ranged quasi-perfect actions can yield strong improvement is most
relevant in view of QCD.Comment: 30 pages, 16 figures. Following the referee's suggestions, we have
incorporated the material of hep-lat/9803018 in this comprehensive pape
Fixed Point Gauge Actions with Fat Links: Scaling and Glueballs
A new parametrization is introduced for the fixed point (FP) action in SU(3)
gauge theory using fat links. We investigate its scaling properties by means of
the static quark-antiquark potential and the dimensionless quantities and , where is the critical
temperature of the deconfining phase transition, is the hadronic scale
and is the effective string tension. These quantities scale even on
lattices as coarse as fm. We also measure the glueball spectrum
and obtain MeV and MeV for the
masses of the scalar and tensor glueballs, respectively.Comment: 45 pages, 12 figures, Late
Strategic responses to global challenges: The case of European banking, 1973â2000
In applying a strategy, structure, ownership and performance (SSOP) framework to three major clearing banks (ABN AMRO, UBS, Barclays), this article debates whether the conclusions generated by Whittington and Mayer about European manufacturing industry can be applied to the financial services sector. While European integration plays a key role in determining strategy, it is clear that global factors were far more important in determining management actions, leading to significant differences in structural adaptation. The article also debates whether this has led to improved performance, given the problems experienced with both geographical dispersion and diversification, bringing into question the quality of decision-making over the long term
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