76 research outputs found
The cosmological constant from the QCD Veneziano ghost
We suggest that the solution to the cosmological vacuum energy puzzle is
linked to the infrared sector of the effective theory of gravity interacting
with standard model fields, with QCD fields specifically. We work in the
framework of low energy quantum gravity as an effective field theory. In
particular, we compute the vacuum energy in terms of QCD parameters and the
Hubble constant such that the vacuum energy is \epsilon_{vac} \sim H \cdot
m_q\la\bar{q}q\ra /m_{\eta'} \sim (3.6\cdot 10^{-3} \text{eV})^4, which is
amazingly close to the observed value today. The QCD ghost (responsible for the
solution of the problem) plays a crucial r\^ole in the computation of
the vacuum energy, because the ghost's properties at very large but finite
distances slightly deviate (as \sim H / \Lqcd ) from their infinite volume
Minkowski values. Another important prediction of this framework states that
the vacuum energy owes its existence to the asymmetry of the cosmos. Indeed,
this effect is a direct consequence of the embedding of our Universe on a
non-trivial manifold such as a torus with (slightly) different linear sizes.
Such a violation of cosmological isotropy is apparently indeed supported by
WMAP, and will be confirmed (or ruled out) by future PLANCK data.Comment: 4 pages, uses revtex4, v2 as publishe
Initial Vortex Densities after a Temperature Quench
We calculate the initial density of relativistic global vortices (strings)
produced at a quench and contrast it with the predictions of Kibble and Zurek.Comment: Latex file, 8 pages, No figures. The text contains minor changes that
elucidate the onset of classical behaviour more thoroughly. Also including
the word temperature in the title makes the nature of the transition more
explici
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The Effect of Salsalate Therapy on Endothelial Function in a Broad Range of Subjects
Background: Inflammation is fundamental to the development of atherosclerosis. We examined the effect of antiâinflammatory doses of salicylate on endotheliumâdependent vasodilation, a biomarker of cardiovascular risk, in a broad range of subjects. Methods and Results: We performed a randomized, doubleâblind, placeboâcontrolled crossover trial evaluating the effects of 4 weeks of highâdose salsalate (disalicylate) therapy on endotheliumâdependent flowâmediated and endotheliumâindependent vasodilation. Fiftyâeight subjects, including 17 with metabolic syndrome, 13 with atherosclerosis, and 28 healthy controls, were studied. Among all subjects, endotheliumâdependent flowâmediated vasodilation decreased after salsalate compared with placebo therapy (P=0.01), whereas nitroglycerinâmediated, endotheliumâindependent vasodilation was unchanged (P=0.97). Endotheliumâdependent flowâmediated vasodilation after salsalate therapy was impaired compared with placebo therapy in subjects with therapeutic salicylate levels (n=31, P0.2). Conclusions: Salsalate therapy, particularly when therapeutic salicylate levels are achieved, impairs endotheliumâdependent vasodilation in a broad range of subjects. These data raise concern about the possible deleterious effects of antiâinflammatory doses of salsalate on cardiovascular risk. Clinical Trial Registration URL: www.clinicaltrials.gov. Unique Identifiers: NCT00760019 and NCT00762827
Slow Quenches Produce Fuzzy, Transient Vortices
We examine the Zurek scenario for the production of vortices in quenches of
liquid in the light of recent experiments. Extending our previous
results to later times, we argue that short wavelength thermal fluctuations
make vortices poorly defined until after the transition has occurred. Further,
if and when vortices appear, it is plausible that that they will decay faster
than anticipated from turbulence experiments, irrespective of quench rates.Comment: 4 pages, Revtex file, no figures Apart from a more appropriate title,
this paper differs from its predecessor by including temperature, as well as
pressure, quenche
Challenges and solutions for the implementation of shared decision-making in breast reconstruction
Treatment outcomes and late toxicities in patients with embryonal central nervous system tumors
Cellular magnesium acquisition : an anomaly in embryonic cation homeostasis
Author Posting. © The Author(s), 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Experimental and Molecular Pathology 83 (2007): 224-240, doi:10.1016/j.yexmp.2007.03.007.The intracellular dominance of magnesium ion makes clinical assessment difficult despite the critical role of Mg++ in many key functions of cells and enzymes. There is general consensus that serum Mg++ levels are not representative of the growing number of conditions for which magnesium is known to be important. There is no consensus method or sample source for testing for clinical purposes. High intracellular Mg++ in vertebrate embryos results in part from interactions of cations which influence cell membrane transport systems. These are functionally competent from the earliest stages, at least transiently held over from the unfertilized ovum. Kinetic studies with radiotracer cations, osmolar variations, media lacking one or more of the four biological cations, Na+, Mg++, K+, and Ca++, and metabolic poison 0.05 mEq/L NaF, demonstrated: (1) all four cations influence the behavior of the others, and (2) energy is required for uptake and efflux on different time scales, some against gradient. Na+ uptake is energy dependent against an efflux gradient. The rate of K+ loss is equal with or without fluoride, suggesting a lack of an energy requirement at these stages. Ca++ efflux took twice as long in the presence of fluoride, likely due in part to intracellular binding. Mg++ is anomalous in that early teleost vertebrate embryos have an intracellular content exceeding the surrounding sea water, an isolated unaffected yolk compartment, and a clear requirement for energy for both uptake and efflux. The physiological, pathological, and therapeutic roles of magnesium are poorly understood. This will change: (1) when 28Mg is once again generally available at a reasonable cost for both basic research and clinical assessment, and (2) when serum or plasma levels are determined simultaneously with intracellular values, preferably as part of complete four cation profiles. Atomic absorption spectrophotometry, energy-dispersive x-ray analysis, and inductively coupled plasma emission spectroscopy on sublingual mucosal and peripheral blood samples are potential methods of value for coordinated assessments.AEC Grant No. 134
Acute wound infections management: the âDonâtsâ from a multidisciplinary expert panel
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