533 research outputs found
The role of hyperbaric oxygen therapy in ischaemic diabetic lower extremity ulcers: A double-blind randomised-controlled trial
AbstractObjective: ischaemic lower-extremity ulcers in the diabetic population are a source of major concern because of the associated high risk of limb-threatening complications. The aim of this study was to evaluate the role of hyperbaric oxygen in the management of these ulcers. Method: eighteen diabetic patients with ischaemic, non-healing lower-extremity ulcers were recruited in a double-blind study. Patients were randomly assigned either to receive 100% oxygen (treatment group) or air (control group), at 2.4 atmospheres of absolute pressure for 90 min daily (total of 30 treatments). Results: healing with complete epithelialisation was achieved in five out of eight ulcers in the treatment group compared to one out of eight ulcers in the control group. The median decrease of the wound areas in the treatment group was 100% and in the control group was 52% (p = 0.027). Cost-effectiveness analysis has shown that despite the extra cost involved in using hyperbaric oxygen, there was a potential saving in the total cost of treatment for each patient during the study. Conclusion: hyperbaric oxygen enhanced the healing of ischaemic, non-healing diabetic leg ulcers and may be used as a valuable adjunct to conventional therapy when reconstructive surgery is not possible.Eur J Vasc Endovasc Surg 25, 513-518 (2003
The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER). III. The Mass Function of Young Star Clusters in M33
We measure the star cluster mass function for the Local Group galaxy M33. We
use the catalog of stellar clusters selected from the Panchromatic Hubble
Andromeda Treasury: Triangulum Extended Region (PHATTER) survey. We analyze 711
clusters in M33 with
3.0 as determined from color-magnitude diagram fits to individual stars. The
M33 cluster mass function is best described by a Schechter function with power
law slope , and truncation mass
log() . The data show strong evidence
for a high-mass truncation, thus strongly favoring a Schechter function fit
over a pure power law. M33's truncation mass is consistent with the previously
identified linear trend between , and star formation rate surface density,
\SigSFR. We also explore the effect that individual cluster mass uncertainties
have on derived mass function parameters, and find evidence to suggest that
large cluster mass uncertainties have the potential to bias the truncation mass
of fitted mass functions on the one sigma level.Comment: 18 pages, 15 figures, 1 table, Accepted to ApJ (February 2, 2022
Indirect techniques in nuclear astrophysics. Asymptotic Normalization Coefficient and Trojan Horse
Owing to the presence of the Coulomb barrier at astrophysically relevant
kinetic energies it is very difficult, or sometimes impossible, to measure
astrophysical reaction rates in the laboratory. That is why different indirect
techniques are being used along with direct measurements. Here we address two
important indirect techniques, the asymptotic normalization coefficient (ANC)
and the Trojan Horse (TH) methods. We discuss the application of the ANC
technique for calculation of the astrophysical processes in the presence of
subthreshold bound states, in particular, two different mechanisms are
discussed: direct capture to the subthreshold state and capture to the
low-lying bound states through the subthreshold state, which plays the role of
the subthreshold resonance. The ANC technique can also be used to determine the
interference sign of the resonant and nonresonant (direct) terms of the
reaction amplitude. The TH method is unique indirect technique allowing one to
measure astrophysical rearrangement reactions down to astrophysically relevant
energies. We explain why there is no Coulomb barrier in the sub-process
amplitudes extracted from the TH reaction. The expressions for the TH amplitude
for direct and resonant cases are presented.Comment: Invited talk on the Conference "Nuclear Physics in Astrophysics II",
Debrecen, Hungary, 16-20 May, 200
Perioperative, postoperative, and long-term outcomes following open surgical repair of ruptured abdominal aortic aneurysm
We investigated factors that affected perioperative, postoperative, and long-term outcomes of patients who underwent open emergency surgical repair of ruptured abdominal aortic aneurysms (RAAA). All patients who underwent open emergency surgical repair from 1990 to 2011 were included (463 patients; 374 [81%] male; mean age 74.7 ± 8.7years). Logistic and Cox regression analyses were performed to explore the association of variables with outcomes. Preoperatively, median (interquartile range) hemoglobin was 11.2 (9.5-12.8) g/dL, and median creatinine level was 140 (112-177) µmol/L. Intraoperatively, the median operative time was 2.25 (2-3) hours, and median estimated blood loss was 1.5 (0.5-3) L; 250 (54%) patients required intraoperative inotropes, and a median of 6 (4-8) units of blood was transfused. Median length of hospital stay was 11 (7-20) days. In-hospital mortality rate was 35.6%, and 5-year mortality was 48%. Age, distance traveled, operation duration, postoperative myocardial infarction (MI), and multi-organ failure (MOF) were predictors of in-hospital mortality and long-term outcome. Additionally, postoperative acute renal failure predicted in-hospital mortality. In patients with RAAA undergoing open surgical repair, the strongest predictors of in-hospital mortality and long-term outcome were postoperative MOF and MI and operative duration
The detection of Gravitational Waves
This chapter is concerned with the question: how do gravitational waves (GWs)
interact with their detectors? It is intended to be a theory review of the
fundamental concepts involved in interferometric and acoustic (Weber bar) GW
antennas. In particular, the type of signal the GW deposits in the detector in
each case will be assessed, as well as its intensity and deconvolution. Brief
reference will also be made to detector sensitivity characterisation, including
very summary data on current state of the art GW detectors.Comment: 33 pages, 12 figures, LaTeX2e, Springer style files --included. For
Proceedings of the ERE-2001 Conference (Madrid, September 2001
Negative Kaons in Dense Baryonic Matter
Kaon polarization operator in dense baryonic matter of arbitrary isotopic
composition is calculated including s- and p-wave kaon-baryon interactions. The
regular part of the polarization operator is extracted from the realistic
kaon-nucleon interaction based on the chiral and 1/N_c expansion. Contributions
of the Lambda(1116), Sigma(1195), Sigma*(1385) resonances are taken explicitly
into account in the pole and regular terms with inclusion of mean-field
potentials. The baryon-baryon correlations are incorporated and fluctuation
contributions are estimated. Results are applied for K- in neutron star matter.
Within our model a second-order phase transition to the s-wave K- condensate
state occurs at rho_c \gsim 4 \rho_0 once the baryon-baryon correlations are
included. We show that the second-order phase transition to the p-wave
condensate state may occur at densities in
dependence on the parameter choice. We demonstrate that a first-order phase
transition to a proton-enriched (approximately isospin-symmetric) nucleon
matter with a p-wave K- condensate can occur at smaller densities, \rho\lsim 2
\rho_0. The transition is accompanied by the suppression of hyperon
concentrations.Comment: 41 pages, 24 figures, revtex4 styl
Answering a Basic Objection to Bang/Crunch Holography
The current cosmic acceleration does not imply that our Universe is basically
de Sitter-like: in the first part of this work we argue that, by introducing
matter into *anti-de Sitter* spacetime in a natural way, one may be able to
account for the acceleration just as well. However, this leads to a Big Crunch,
and the Euclidean versions of Bang/Crunch cosmologies have [apparently]
disconnected conformal boundaries. As Maldacena and Maoz have recently
stressed, this seems to contradict the holographic principle. In the second
part we argue that this "double boundary problem" is a matter not of geometry
but rather of how one chooses a conformal compactification: if one chooses to
compactify in an unorthodox way, then the appearance of disconnectedness can be
regarded as a *coordinate effect*. With the kind of matter we have introduced
here, namely a Euclidean axion, the underlying compact Euclidean manifold has
an unexpectedly non-trivial topology: it is in fact one of the 75 possible
underlying manifolds of flat compact four-dimensional Euclidean spaces.Comment: 29 pages, 3 figures, added references and comparison with "cyclic"
cosmology, JHEP versio
Determination of Turbine Blade Life from Engine Field Data
It is probable that no two engine companies determine the life of their engines or their components in the same way or apply the same experience and safety factors to their designs. Knowing the failure mode that is most likely to occur minimizes the amount of uncertainty and simplifies failure and life analysis. Available data regarding failure mode for aircraft engine blades, while favoring low-cycle, thermal mechanical fatigue as the controlling mode of failure, are not definitive. Sixteen high-pressure turbine (HPT) T-1 blade sets were removed from commercial aircraft engines that had been commercially flown by a single airline and inspected for damage. Each set contained 82 blades. The damage was cataloged into three categories related to their mode of failure: (1) Thermal-mechanical fatigue, (2) Oxidation/Erosion, and (3) "Other." From these field data, the turbine blade life was determined as well as the lives related to individual blade failure modes using Johnson-Weibull analysis. A simplified formula for calculating turbine blade life and reliability was formulated. The L(sub 10) blade life was calculated to be 2427 cycles (11 077 hr). The resulting blade life attributed to oxidation/erosion equaled that attributed to thermal-mechanical fatigue. The category that contributed most to blade failure was Other. If there were there no blade failures attributed to oxidation/erosion and thermal-mechanical fatigue, the overall blade L(sub 10) life would increase approximately 11 to 17 percent
HI in the Outskirts of Nearby Galaxies
The HI in disk galaxies frequently extends beyond the optical image, and can
trace the dark matter there. I briefly highlight the history of high spatial
resolution HI imaging, the contribution it made to the dark matter problem, and
the current tension between several dynamical methods to break the disk-halo
degeneracy. I then turn to the flaring problem, which could in principle probe
the shape of the dark halo. Instead, however, a lot of attention is now devoted
to understanding the role of gas accretion via galactic fountains. The current
cold dark matter theory has problems on galactic scales, such as
the core-cusp problem, which can be addressed with HI observations of dwarf
galaxies. For a similar range in rotation velocities, galaxies of type Sd have
thin disks, while those of type Im are much thicker. After a few comments on
modified Newtonian dynamics and on irregular galaxies, I close with statistics
on the HI extent of galaxies.Comment: 38 pages, 17 figures, invited review, book chapter in "Outskirts of
Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and
Space Science Library, Springer, in pres
- …