4,115 research outputs found
Facing Up to Unpalatable Evidence for the Sake of Our Patients
Paul Mullen discusses Seena Fazel and colleagues' paper on the association between violent behavior and having been diagnosed with a schizophrenic disorder, and its implications for care of these individuals
Racial Disparities in Intravenous Recombinant Tissue Plasminogen Activator Use Persist at Primary Stroke Centers.
BACKGROUND: Primary stroke centers (PSCs) utilize more recombinant tissue plasminogen activator (rt-PA) than non-PSCs. The impact of PSCs on racial disparities in rt-PA use is unknown.
METHODS AND RESULTS: We used data from the Nationwide Inpatient Sample from 2004 to 2010, limited to states that publicly reported hospital identity and race. Hospitals certified as PSCs by The Joint Commission were identified. Adults with a diagnosis of ischemic stroke were analyzed. Rt-PA use was defined by the International Classification of Diseases, 9th Revision procedure code 99.10. Discharges (304 152 patients) from 26 states met eligibility criteria, and of these 71.5% were white, 15.0% black, 7.9% Hispanic, and 5.6% other. Overall, 24.7% of white, 27.4% of black, 16.2% of Hispanic, and 29.8% of other patients presented to PSCs. A higher proportion received rt-PA at PSCs than non-PSCs in all race/ethnic groups (white 7.6% versus 2.6%, black 4.8% versus 2.0%, Hispanic 7.1% versus 2.4%, other 7.2% versus 2.5%, all P
CONCLUSIONS: Racial disparities in intravenous rt-PA use were not reduced by presentation to PSCs. Black patients were less likely to receive thrombolytic treatment than white patients at both non-PSCs and PSCs. Hispanic patients were less likely to be seen at PSCs relative to white patients and were less likely to receive intravenous rt-PA in the fully adjusted model
Geometrical Defects in Josephson Junction Arrays
Dislocations and disclinations in a lattice of Josephson junctions will
affect the dynamics of vortex excitations within the array. These defects
effectively distort the space in which the excitations move and interact. The
interaction energy between such defects and excitations are determined and
vortex trajectories in twisted lattices are calculated. Finally, possible
experiments observing these effects are presented.Comment: 26 pages including 5 figure
First Principles Analysis of Electron-Phonon Interaction in Graphene
The electron-phonon interaction in monolayer graphene is investigated by
using density functional perturbation theory. The results indicate that the
electron-phonon interaction strength is of comparable magnitude for all four
in-plane phonon branches and must be considered simultaneously. Moreover, the
calculated scattering rates suggest an acoustic phonon contribution that is
much weaker than previously thought, revealing the role of optical phonons even
at low energies. Accordingly it is predicted, in good agreement with a recent
measurement, that the intrinsic mobility of graphene may be more than an order
of magnitude larger than the high values reported in suspended samples.Comment: 12 pages, 4 figure
Deviations from the local field approximation in negative streamer heads
Negative streamer ionization fronts in nitrogen under normal conditions are
investigated both in a particle model and in a fluid model in local field
approximation. The parameter functions for the fluid model are derived from
swarm experiments in the particle model. The front structure on the inner scale
is investigated in a 1D setting, allowing reasonable run-time and memory
consumption and high numerical accuracy without introducing super-particles. If
the reduced electric field immediately before the front is >= 50kV/(cm bar),
solutions of fluid and particle model agree very well. If the field increases
up to 200kV/(cm bar), the solutions of particle and fluid model deviate, in
particular, the ionization level behind the front becomes up to 60% higher in
the particle model while the velocity is rather insensitive. Particle and fluid
model deviate because electrons with high energies do not yet fully run away
from the front, but are somewhat ahead. This leads to increasing ionization
rates in the particle model at the very tip of the front. The energy overshoot
of electrons in the leading edge of the front actually agrees quantitatively
with the energy overshoot in the leading edge of an electron swarm or avalanche
in the same electric field.Comment: The paper has 17 pages, including 15 figures and 3 table
Augmenter of liver regeneration enhances the success rate of fetal pancreas transplantation in rodents
Background. Treatment of fetal pancreas (FP) isografts with insulin- like growth factor-I greatly improves the rate of conversion to euglycemia in diabetic rats. Complete knowledge of other factors that may facilitate the engraftment and function of FP in vivo is still embryonic. Augmenter of liver regeneration (ALR) is a newly described polypeptide growth factor found in weanling rat livers. ALR has trophic effects on regenerating liver. We studied the effects of in situ administration of this agent on FP isografts in rats. Methods. Streptozotocin-diabetic Lewis rats (blood glucose >300 mg/dl) received 16 FP isografts transplanted intramuscularly. ALR was delivered from day 1 through day 14, in doses of 40 or 400 ng/kg/d. Animals were followed for 3 months with serial weights and blood glucose monitoring. These animals were compared with those treated with vehicle alone. Results. Of the group treated with ALR at 40 ng/kg/day for 14 days, 89% (eight of nine) were euglycemic (P=0.0003). Of the group treated with ALR at 400 ng/kg/day for 14 days, 88% (seven of eight) were euglycemic (P=0.0007). Of the group treated with vehicle alone, none of the six were euglycemic. Euglycemia is defined here as glucose<200 mg/dl for 3 days. Pathology of the intramuscular transplant site showed patches of islet tissue embedded in fat. These patches demonstrated insulin immunoreactivity. Conclusions. Diabetes was reversed in a significantly greater proportion of FP + ALR-treated recipients than those animals treated with vehicle alone. Local delivery of growth factors my be used as an adjunct to FP transplantation to improve the rate of success. This in situ model may be useful to further evaluate other soluble factors
Analysis of experimental shaft seal data for high-performance turbomachines, as for Space Shuttle main engines
High-pressure, high-temperature seal flow (leakage) data for nonrotating and rotating Raleigh-step and convergent-tapered-bore seals were characterized in terms of a normalized flow coefficient. The data for normalized Rayleigh-steip and nonrotating tapered-bore seals were in reasonable agreement with theory, but data for the rotating tapered-bore seals were not. The tapered-bore-seal operational clearances estimated from the flow data were significantly larger than calculated. Although clearances are influenced by wear from conical to cylindrical geometry and errors in clearance corrections, the problem was isolated to the shaft temperature - rotational speed clearance correction. The geometric changes support the use of some conical convergence in any seal. Under these conditions rotation reduced the normalized flow coefficiently by nearly 10 percent
An accurate effective action for `baby' to `adult' skyrmions
Starting with a Chern-Simons theory, we derive an effective action for
interacting quantum Hall skyrmions that takes into account both large-distance
physics and short-distance details as well. We numerically calculate the
classical static skyrmion profile from this action and find excellent agreement
with other, microscopic calculations over a wide range of skyrmion sizes
including the experimentally relevant one. This implies that the essential
physics of this regime might be captured by a continuum classical model rather
than resorting to more microscopic approaches. We also show that the skyrmion
energy closely follows the formula suggested earlier by Sondhi et al. for a
broad parameter range of interest as well.Comment: 13 pages (Revtex) + 3 ps-figure
Development of light weight magnesium alloys for low temperature applications Annual progress report, Jun. 19, 1965 - Mar. 20, 1966
Lightweight magnesium alloys for cryogenic application
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