9 research outputs found
Does gravity prefer the Poincare dodecahedral space?
The missing fluctuations problem in cosmic microwave background observations
is naturally explained by well-proportioned small universe models. Among the
well-proportioned models, the Poincare dodecahedral space is empirically
favoured. Does gravity favour this space? The residual gravity effect is the
residual acceleration induced by weak limit gravity from multiple topological
images of a massive object on a nearby negligible mass test object. At the
present epoch, the residual gravity effect is about a million times weaker in
three of the well-proportioned spaces than in ill-proportioned spaces. However,
in the Poincare space, the effect is 10,000 times weaker still, i.e. the
Poincare space is about 10^{10} times "better balanced" than ill-proportioned
spaces. Both observations and weak limit dynamics select the Poincare space to
be special.Comment: 6 pages, Honorable Mention in 2009 Gravity Research Foundation essay
competitio
Dynamical Casimir Effect with Semi-Transparent Mirrors, and Cosmology
After reviewing some essential features of the Casimir effect and,
specifically, of its regularization by zeta function and Hadamard methods, we
consider the dynamical Casimir effect (or Fulling-Davis theory), where related
regularization problems appear, with a view to an experimental verification of
this theory. We finish with a discussion of the possible contribution of vacuum
fluctuations to dark energy, in a Casimir like fashion, that might involve the
dynamical version.Comment: 11 pages, Talk given in the Workshop ``Quantum Field Theory under the
Influence of External Conditions (QFEXT07)'', Leipzig (Germany), September 17
- 21, 200
Are Small Hyperbolic Universes Observationally Detectable?
Using recent observational constraints on cosmological density parameters,
together with recent mathematical results concerning small volume hyperbolic
manifolds, we argue that, by employing pattern repetitions, the topology of
nearly flat small hyperbolic universes can be observationally undetectable.
This is important in view of the facts that quantum cosmology may favour
hyperbolic universes with small volumes, and from the expectation coming from
inflationary scenarios, that is likely to be very close to one.Comment: 5 pages, 1 figure, LaTeX2e. A reference and two footnotes added. To
appear in Class. Quantum Grav. 18 (2001) in the present for
Three-dimensional Topology-Independent Methods to Look for Global Topology
The space-like hypersurface of the Universe at the present cosmological time
is a three-dimensional manifold. A non-trivial global topology of this
space-like hypersurface would imply that the apparently observable universe
(the sphere of particle horizon radius) could contain several images of the
single, physical Universe. Recent three-dimensional techniques for constraining
and/or detecting this topology are reviewed. Initial applications of these
techniques using X-ray bright clusters of galaxies and quasars imply (weak)
candidates for a non-trivial topology.Comment: minor revision; 7 pages, 1 figure, accepted by Classical and Quantum
Gravit
Zeta Function Methods and Quantum Fluctuations
A review of some recent advances in zeta function techniques is given, in
problems of pure mathematical nature but also as applied to the computation of
quantum vacuum fluctuations in different field theories, and specially with a
view to cosmological applications.Comment: 17 pages, Talk given at the Conference ``Quantum Theory and
Symmetries - 5'', Valladolid (Spain), July 22 - 28, 200
Candida bloodstream infections in intensive care units: analysis of the extended prevalence of infection in intensive care unit study
Item does not contain fulltextOBJECTIVES: To provide a global, up-to-date picture of the prevalence, treatment, and outcomes of Candida bloodstream infections in intensive care unit patients and compare Candida with bacterial bloodstream infection. DESIGN: A retrospective analysis of the Extended Prevalence of Infection in the ICU Study (EPIC II). Demographic, physiological, infection-related and therapeutic data were collected. Patients were grouped as having Candida, Gram-positive, Gram-negative, and combined Candida/bacterial bloodstream infection. Outcome data were assessed at intensive care unit and hospital discharge. SETTING: EPIC II included 1265 intensive care units in 76 countries. PATIENTS: Patients in participating intensive care units on study day. INTERVENTIONS: None. MEASUREMENT AND MAIN RESULTS: Of the 14,414 patients in EPIC II, 99 patients had Candida bloodstream infections for a prevalence of 6.9 per 1000 patients. Sixty-one patients had candidemia alone and 38 patients had combined bloodstream infections. Candida albicans (n = 70) was the predominant species. Primary therapy included monotherapy with fluconazole (n = 39), caspofungin (n = 16), and a polyene-based product (n = 12). Combination therapy was infrequently used (n = 10). Compared with patients with Gram-positive (n = 420) and Gram-negative (n = 264) bloodstream infections, patients with candidemia were more likely to have solid tumors (p < .05) and appeared to have been in an intensive care unit longer (14 days [range, 5-25 days], 8 days [range, 3-20 days], and 10 days [range, 2-23 days], respectively), but this difference was not statistically significant. Severity of illness and organ dysfunction scores were similar between groups. Patients with Candida bloodstream infections, compared with patients with Gram-positive and Gram-negative bloodstream infections, had the greatest crude intensive care unit mortality rates (42.6%, 25.3%, and 29.1%, respectively) and longer intensive care unit lengths of stay (median [interquartile range]) (33 days [18-44], 20 days [9-43], and 21 days [8-46], respectively); however, these differences were not statistically significant. CONCLUSION: Candidemia remains a significant problem in intensive care units patients. In the EPIC II population, Candida albicans was the most common organism and fluconazole remained the predominant antifungal agent used. Candida bloodstream infections are associated with high intensive care unit and hospital mortality rates and resource use
Candida bloodstream infections in intensive care units: analysis of the extended prevalence of infection in intensive care unit study
To provide a global, up-to-date picture of the prevalence, treatment, and outcomes of Candida bloodstream infections in intensive care unit patients and compare Candida with bacterial bloodstream infection.
DESIGN:
A retrospective analysis of the Extended Prevalence of Infection in the ICU Study (EPIC II). Demographic, physiological, infection-related and therapeutic data were collected. Patients were grouped as having Candida, Gram-positive, Gram-negative, and combined Candida/bacterial bloodstream infection. Outcome data were assessed at intensive care unit and hospital discharge.
SETTING:
EPIC II included 1265 intensive care units in 76 countries.
PATIENTS:
Patients in participating intensive care units on study day.
INTERVENTIONS:
None.
MEASUREMENT AND MAIN RESULTS:
Of the 14,414 patients in EPIC II, 99 patients had Candida bloodstream infections for a prevalence of 6.9 per 1000 patients. Sixty-one patients had candidemia alone and 38 patients had combined bloodstream infections. Candida albicans (n = 70) was the predominant species. Primary therapy included monotherapy with fluconazole (n = 39), caspofungin (n = 16), and a polyene-based product (n = 12). Combination therapy was infrequently used (n = 10). Compared with patients with Gram-positive (n = 420) and Gram-negative (n = 264) bloodstream infections, patients with candidemia were more likely to have solid tumors (p < .05) and appeared to have been in an intensive care unit longer (14 days [range, 5-25 days], 8 days [range, 3-20 days], and 10 days [range, 2-23 days], respectively), but this difference was not statistically significant. Severity of illness and organ dysfunction scores were similar between groups. Patients with Candida bloodstream infections, compared with patients with Gram-positive and Gram-negative bloodstream infections, had the greatest crude intensive care unit mortality rates (42.6%, 25.3%, and 29.1%, respectively) and longer intensive care unit lengths of stay (median [interquartile range]) (33 days [18-44], 20 days [9-43], and 21 days [8-46], respectively); however, these differences were not statistically significant.
CONCLUSION:
Candidemia remains a significant problem in intensive care units patients. In the EPIC II population, Candida albicans was the most common organism and fluconazole remained the predominant antifungal agent used. Candida bloodstream infections are associated with high intensive care unit and hospital mortality rates and resource use