3,229 research outputs found
Recommended from our members
Frameworks for Failure, or What Happened to the Social Turn in Writing Studies?
Refined topological amplitudes in N=1 flux compactification
We study the implication of refined topological string amplitudes in the
supersymmetric N=1 flux compactification. They generate higher derivative
couplings among the vector multiplets and graviphoton with generically
non-holomorphic moduli dependence. For a particular term, we can compute them
by assuming the geometric engineering. We claim that the Dijkgraaf-Vafa large N
matrix model with the beta-ensemble measure directly computes the higher
derivative corrections to the supersymmetric effective action of the
supersymmetric N=1$ gauge theory.Comment: 16 pages, v2: reference adde
Evaluation of the efficacy of Alpron disinfectant for dental unit water lines
AIMS: To assess the efficacy of a disinfectant, Alpron, for controlling microbial contamination within dental unit water lines. METHODS: The microbiological quality of water emerging from the triple syringe, high speed handpiece, cup filler and surgery hand wash basin from six dental units was assessed for microbiological total viable counts at 22 degrees C and 37 degrees C before and after treatment with Alpron solutions. RESULTS: The study found that the use of Alpron disinfectant solutions could reduce microbial counts in dental unit water lines to similar levels for drinking water. This effect was maintained in all units for up to six weeks following one course of treatment. In four out of six units the low microbial counts were maintained for 13 weeks. CONCLUSIONS: Disinfectants may have a short term role to play in controlling microbial contamination of dental unit water lines to drinking water quality. However, in the longer term attention must be paid to redesigning dental units to discourage the build up of microbial biofilms
Dual Identities inside the Gluon and the Graviton Scattering Amplitudes
Recently, Bern, Carrasco and Johansson conjectured dual identities inside the
gluon tree scattering amplitudes. In this paper, we use the properties of the
heterotic string and open string tree scattering amplitudes to refine and
derive these dual identities. These identities can be carried over to loop
amplitudes using the unitarity method. Furthermore, given the -gluon (as
well as gluon-gluino) tree amplitudes, -graviton (as well as
graviton-gravitino) tree scattering amplitudes can be written down immediately,
avoiding the derivation of Feynman rules and the evaluation of Feynman diagrams
for graviton scattering amplitudes.Comment: 43 pages, 3 figures; typos corrected, a few points clarified
Introduction to Chiral Perturbation Theory
A brief introduction to chiral perturbation theory, the effective field
theory of quantum chromodynamics at low energies, is given.Comment: 26 pages, 11 figures. Lectures given at the summer school ISSSMB 2006
in Akyaka, Turkey, September 200
Relationship between FEV1 change and patient-reported outcomes in randomised trials of inhaled bronchodilators for stable COPD: a systematic review.
BACKGROUND: Interactions between spirometry and patient-reported outcomes in COPD are not well understood. This systematic review and study-level analysis investigated the relationship between changes in FEV1 and changes in health status with bronchodilator therapy.
METHODS: Six databases (to October 2009) were searched to identify studies with long-acting bronchodilator therapy reporting FEV1 and health status, dyspnoea or exacerbations. Mean and standard deviations of treatment effects were extracted for each arm of each study. Relationships between changes in trough FEV1 and outcomes were assessed using correlations and random-effects regression modelling. The primary outcome was St George's Respiratory Questionnaire (SGRQ) total score.
RESULTS: Thirty-six studies (≥ 3 months) were included. Twenty-two studies (23,654 patients) with 49 treatment arms each contributing one data point provided SGRQ data. Change in trough FEV1 and change in SGRQ total score were negatively correlated (r = -0.46, p < 0.001); greater increases in FEV1 were associated with greater reductions (improvements) in SGRQ. The correlation strengthened with increasing study duration from 3 to 12 months. Regression modelling indicated that 100 mL increase in FEV1 (change at which patients are more likely to report improvement) was associated with a statistically significant reduction in SGRQ of 2.5 (95% CI 1.9, 3.1), while a clinically relevant SGRQ change (4.0) was associated with 160.6 (95% CI 129.0, 211.6) mL increase in FEV1. The association between change in FEV1 and other patient-reported outcomes was generally weak.
CONCLUSIONS: Our analyses indicate, at a study level, that improvement in mean trough FEV1 is associated with proportional improvements in health status
Theory of dynamic crack branching in brittle materials
The problem of dynamic symmetric branching of an initial single brittle crack
propagating at a given speed under plane loading conditions is studied within a
continuum mechanics approach. Griffith's energy criterion and the principle of
local symmetry are used to determine the cracks paths. The bifurcation is
predicted at a given critical speed and at a specific branching angle: both
correlated very well with experiments. The curvature of the subsequent branches
is also studied: the sign of , with being the non singular stress at the
initial crack tip, separates branches paths that diverge from or converge to
the initial path, a feature that may be tested in future experiments. The model
rests on a scenario of crack branching with some reasonable assumptions based
on general considerations and in exact dynamic results for anti-plane
branching. It is argued that it is possible to use a static analysis of the
crack bifurcation for plane loading as a good approximation to the dynamical
case. The results are interesting since they explain within a continuum
mechanics approach the main features of the branching instabilities of fast
cracks in brittle materials, i.e. critical speeds, branching angle and the
geometry of subsequent branches paths.Comment: 41 pages, 15 figures. Accepted to International Journal of Fractur
Quantum gravitational contributions to quantum electrodynamics
Quantum electrodynamics describes the interactions of electrons and photons.
Electric charge (the gauge coupling constant) is energy dependent, and there is
a previous claim that charge is affected by gravity (described by general
relativity) with the implication that the charge is reduced at high energies.
But that claim has been very controversial with the situation inconclusive.
Here I report an analysis (free from earlier controversies) demonstrating that
that quantum gravity corrections to quantum electrodynamics have a quadratic
energy dependence that result in the reduction of the electric charge at high
energies, a result known as asymptotic freedom.Comment: To be published in Nature. 19 pages LaTeX, no figure
Padronização da medida do anticorpo anti-decarboxilase do ácido glutâmico (anti-GAD) para o diagnóstico etiológico do Diabete Melito
A rare association of crossed fused renal ectopia
BACKGROUND: Thrombocytopenia and absent radius syndrome (TAR) is a rare genetic disorder. It is an autosomal recessive disorder characterised by radial aplasia and thrombocytopenia that may have additional anomalies. We report a case of TAR syndrome with crossed fused renal ectopia. This anomaly has not been previously reported in association with TAR syndrome. CASE PRESENTATION: A 24 years old female with Thrombocytopenia and absent radius syndrome admitted with pelvic fracture was investigated for recurrent urinary tract infections. Abdominal ultrasonography could not visualise the kidney on right side. Further extensive investigations in the form of intravenous urography (IVU), Magnetic resonance imaging (MRI) and renal isotope scans revealed a crossed fused renal ectopia. CONCLUSION: This report describes the new finding of a crossed fused renal ectopia associated with TAR syndrome that has not been reported before in the literature. Ectopic kidneys have increased susceptibility to develop complications like urinary infections, urolithiasis, and abdominal mass. There is a reported case of TAR syndrome with renal anomaly that developed Wilm's tumor. Finding of crossed fused renal ectopia warrants complete urologic investigation to rule out surgically correctable pathology in the urinary tract
- …