3,736 research outputs found
Additional femoral catheter in combination with popliteal catheter for analgesia after major ankle surgery
Background The contribution of the saphenous nerve in pain after major ankle surgery is unknown. The aim of this study was to evaluate its contribution in this context. Methods Fifty patients were included in this prospective, randomized, controlled study. In all patients [Group P (popliteal) and Group F (popliteal+femoral)], a popliteal catheter was placed before operation and ropivacaine 0.5% (30 ml) administered via this catheter; major ankle surgery was then performed under spinal anaesthesia. In Group PF patients, an additional femoral catheter was sited before operation and ropivacaine 0.5% (10 ml) administered. Six hours after spinal anaesthesia (defined as T0), a continuous infusion of ropivacaine 0.3% (14 ml hâ1) was started through the popliteal catheter until T24. Then, the concentration was reduced to 0.2% until T48. Patients in Group PF received continuous ropivacaine 0.2% (5 ml hâ1) through the femoral catheter from T0 to T48. I.V. morphine patient-controlled analgesia was used as a rescue analgesia. Pain at rest, pain with movement, adverse effects, and i.v. morphine consumption were assessed. Pain at rest and on movement was evaluated 6 months after operation. Results Pain at rest was comparable in the two groups. In Group PF, patients had significantly reduced pain during movement in the postoperative period (P=0.01) and 6 months after operation (P=0.03). Morphine consumption was significantly reduced in Group PF at T0-T24 and T24-T48 (P=0.01). Adverse effects were comparable in both groups. Conclusions The addition of continuous femoral catheter infusion of ropivacaine to a continuous popliteal catheter infusion improved postoperative analgesia during movement after major ankle surgery. This effect was still present 6 months after surger
The Role of a Hot Gas Environment on the Evolution of Galaxies
Most spiral galaxies are found in galaxy groups with low velocity
dispersions; most E/S0 galaxies are found in galaxy groups with relatively high
velocity dispersions. The mass of the hot gas we can observe in the E/S0 groups
via their thermal X-ray emission is, on average, as much as the baryonic mass
of the galaxies in these groups. By comparison, galaxy clusters have as much or
more hot gas than stellar mass. Hot gas in S-rich groups, however, is of low
enough temperature for its X-ray emission to suffer heavy absorption due to
Galactic HI and related observational effects, and hence is hard to detect. We
postulate that such lower temperature hot gas does exist in low velocity
dispersion, S-rich groups, and explore the consequences of this assumption. For
a wide range of metallicity and density, hot gas in S-rich groups can cool in
far less than a Hubble time. If such gas exists and can cool, especially when
interacting with HI in existing galaxies, then it can help link together a
number of disparate observations, both Galactic and extragalactic, that are
otherwise difficult to understand.Comment: 16 pages with one figure. ApJ Letters, in pres
Self-consistent computation of gamma-ray spectra due to proton-proton interactions in black hole systems
In the inner regions of an accretion disk around a black hole, relativistic
protons can interact with ambient matter to produce electrons, positrons and
-rays. The resultant steady state electron and positron particle
distributions are self-consistently computed taking into account Coulomb and
Compton cooling, pair production (due to annihilation)
and pair annihilation. While earlier works used the diffusion approximation to
obtain the particle distributions, here we solve a more general
integro-differential equation that correctly takes into account the large
change in particle energy that occur when the leptons Compton scatter off hard
X-rays. Thus this formalism can also be applied to the hard state of black hole
systems, where the dominant ambient photons are hard X-rays. The corresponding
photon energy spectrum is calculated and compared with broadband data of black
hole binaries in different spectral states. The results indicate that the
-ray spectra ( MeV) of both the soft and hard spectral states
and the entire hard X-ray/-ray spectrum of the ultra-soft state, could
be due to interactions. These results are consistent with the hypothesis
that there always exists in these systems a -ray spectral component due
to interactions which can contribute between 0.5 to 10% of the total
bolometric luminosty. The model predicts that {\it GLAST} would be able to
detect black hole binaries and provide evidence for the presence of non-thermal
protons which in turn would give insight into the energy dissipation process
and jet formation in these systems.Comment: Accepted for publication in MNRA
Topologically massive magnetic monopoles
We show that in the Maxwell-Chern-Simons theory of topologically massive
electrodynamics the Dirac string of a monopole becomes a cone in anti-de Sitter
space with the opening angle of the cone determined by the topological mass
which in turn is related to the square root of the cosmological constant. This
proves to be an example of a physical system, {\it a priory} completely
unrelated to gravity, which nevertheless requires curved spacetime for its very
existence. We extend this result to topologically massive gravity coupled to
topologically massive electrodynamics in the framework of the theory of Deser,
Jackiw and Templeton. These are homogeneous spaces with conical deficit. Pure
Einstein gravity coupled to Maxwell-Chern-Simons field does not admit such a
monopole solution
Algebras generated by two bounded holomorphic functions
We study the closure in the Hardy space or the disk algebra of algebras
generated by two bounded functions, of which one is a finite Blaschke product.
We give necessary and sufficient conditions for density or finite codimension
of such algebras. The conditions are expressed in terms of the inner part of a
function which is explicitly derived from each pair of generators. Our results
are based on identifying z-invariant subspaces included in the closure of the
algebra. Versions of these results for the case of the disk algebra are given.Comment: 22 pages ; a number of minor mistakes have been corrected, and some
points clarified. Conditionally accepted by Journal d'Analyse Mathematiqu
A lower lipschitz condition for the stable subordinator
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47646/1/440_2004_Article_BF00538471.pd
Cosmic Voids: structure, dynamics and galaxies
In this review we discuss several aspects of Cosmic Voids. Voids are a major
component of the large scale distribution of matter and galaxies in the
Universe. They are of instrumental importance for understanding the emergence
of the Cosmic Web. Their relatively simple shape and structure makes them into
useful tools for extracting the value of a variety cosmic parameters, possibly
including even that of the influence of dark energy. Perhaps most promising and
challenging is the issue of the galaxies found within their realm. Not only
does the pristine environment of voids provide a promising testing ground for
assessing the role of environment on the formation and evolution of galaxies,
the dearth of dwarf galaxies may even represent a serious challenge to the
standard view of cosmic structure formation.Comment: 29 pages, 12 figures, invited review COSPA2008, Pohang, Korea. Modern
Physics Letters A, accepted. For high-res version see
http://www.astro.rug.nl/~weygaert/voids.cospa2008.weygaert.pd
Spectroscopy of Po
Prompt, in-beam rays following the reaction Yb + 142 MeV
Si were measured at the ATLAS facility using 10 Compton-suppressed Ge
detectors and the Fragment Mass Analyzer. Transitions in Po were
identified and placed using -ray singles and coincidence data gated on
the mass of the evaporation residues. A level spectrum up to
J10 was established. The structure of Po is more
collective than that observed in the heavier polonium isotopes and indicates
that the structure has started to evolve towards the more collective nature
expected for deformed nuclei.Comment: 8 pages, revtex 3.0, 4 figs. available upon reques
Evaluating the utility of inflammatory markers in the diagnosis of soft tissue abscesses of the forearm and hand
Upper extremity abscesses frequently present to the acute care setting with
inconclusive physical examination and imaging findings. We sought to
investigate the diagnostic accuracy of inflammatory markers including white
blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and C-reactive
protein (CRP). A retrospective cohort study was performed to identify
subjects â„18Â years treated with surgical
debridement of upper extremity abscesses at our institution between January 2012 and December 2015. In this study, 188 patients were screened, and
72 met the inclusion criteria. A confirmed abscess as defined by culture
positivity was present in 67 (93.1â%) cases. The sensitivity of WBC, ESR,
or CRP individually was 0.45, 0.71, and 0.81. The specificity of WBC, ESR, or
CRP individually was 0.80, 0.80, and 0.40. In combination all three markers
when positive had a sensitivity of 0.26 and specificity of 1.0. These values
were similar among patients with diabetes and those with obesity. With the
highest sensitivity and lowest specificity, CRP exhibited the most utility
as a screening test (level IV).</p
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