597 research outputs found
An evaluation of the relative efficacy of an open airway, an oxygen reservoir and continuous positive airway pressure 5 cmH2O on the non-ventilated lung
Publisher's copy made available with the permission of the publisher © Australian Society of AnaesthetistsThe aim of this study, during one-lung ventilation, was to evaluate if oxygenation could be improved by use of a simple oxygen reservoir or application of 5 cmH2O continuous positive airway pressure (CPAP) to the non-ventilated lung compared with an open airway. Twenty-three patients with lung malignancy, undergoing thoracotomy requiring at least 60 minutes of one-lung ventilation before lung lobe excision, were studied. After routine induction and establishment of one-lung ventilation, the three treatments were applied in turn to the same patient in a sequence selected randomly. The first treatment was repeated as a fourth treatment and these results of the repeated treatment averaged to minimize the effect of slow changes. Arterial oxygenation was measured by an arterial blood gas 15 minutes after the application of each treatment. Twenty patients completed the study. Mean PaO2 (in mmHg) was 210.3 (SD 105.5) in the 'OPEN' treatment, 186.0 (SD 109.2) in the 'RESERVOIR' treatment, and 240.5 (SD 116.0) in the 'CPAP' treatment. This overall difference was not quite significant (P=0.058, paired ANOVA), but comparison of the pairs showed that there was a significant better oxygenation only with the CPAP compared to the reservoir treatments (t=2.52, P=0.021). While the effect on the surgical field was not apparent in most patients, in one patient surgery was impeded during CPAP. Our results show that the use of a reservoir does not give oxygenation better than an open tube, and is less effective than the use of CPAP 5 cmH2O on the non-ventilated lung during one-lung ventilation.J. Slimani, W. J. Russell, C. Jurisevichttp://www.aaic.net.au/Article.asp?D=200404
Inelastic Neutron Scattering from the Spin Ladder Compound (VO)2P2O7
We present results from an inelastic neutron scattering experiment on the
candidate Heisenberg spin ladder vanadyl pyrophosphate, (VO)2P2O7. We find
evidence for a spin-wave excitation gap of meV, at a
band minimum near . This is consistent with expectations for
triplet spin waves in (VO)2P2O7 in the spin-ladder model, and is to our
knowledge the first confirmation in nature of a Heisenberg antiferromagnetic
spin ladder.Comment: 11 pages and 2 figures (available as hard copy or postscript files
from the authors, send request to [email protected] or
[email protected]), TEX using jnl, reforder and eqnorder, ORNL-CCIP-94-05
/ RAL-94-04
Effects of Neutrino Oscillation on the Supernova Neutrino Spectrum
The effects of three-flavor neutrino oscillation on the supernova neutrino
spectrum are studied. We calculate the expected event rate and energy spectra,
and their time evolution at the Superkamiokande (SK) and the Sudbury Neutrino
Observatory (SNO), by using a realistic neutrino burst model based on numerical
simulations of supernova explosions. We also employ a realistic density profile
based on a presupernova model for the calculation of neutrino conversion
probability in supernova envelopes. These realistic models and numerical
calculations allow us to quantitatively estimate the effects of neutrino
oscillation in a more realistic way than previous studies. We then found that
the degeneracy of the solutions of the solar neutrino problem can be broken by
the combination of the SK and SNO detections of a future Galactic supernova.Comment: 10 pages, 14 figures, corrected versio
Parasitic helminth infections and the control of human allergic and autoimmune disorders
The profile of global health today presents a striking reciprocal distribution between parasitic diseases in many of the world’s lower-income countries, and ever-increasing levels of inflammatory disorders such as allergy, autoimmunity and inflammatory bowel diseases in the more affluent societies. Attention is particularly focused on helminth worm parasites, which are associated with protection from allergy and inflammation in both epidemiological and laboratory settings. One mechanistic explanation of this is that helminths drive the regulatory arm of the immune system, abrogating the ability of the host to expel the parasites, while also dampening reactivity to many “bystander” specificities. Interest has therefore heightened into whether helminth parasites, or their products, hold therapeutic potential for immunological disorders of the developed world. In this narrative review, progress across a range of trials is discussed, together with prospects for isolating individual molecular mediators from helminths that may offer defined new therapies for inflammatory conditions
Rate-equation calculations of the current flow through two-site molecular device and DNA-based junction
Here we present the calculations of incoherent current flowing through the
two-site molecular device as well as the DNA-based junction within the
rate-equation approach. Few interesting phenomena are discussed in detail.
Structural asymmetry of two-site molecule results in rectification effect,
which can be neutralized by asymmetric voltage drop at the molecule-metal
contacts due to coupling asymmetry. The results received for poly(dG)-poly(dC)
DNA molecule reveal the coupling- and temperature-independent saturation effect
of the current at high voltages, where for short chains we establish the
inverse square distance dependence. Besides, we document the shift of the
conductance peak in the direction to higher voltages due to the temperature
decrease.Comment: 12 pages, 6 figure
Phase diagrams of spin ladders with ferromagnetic legs
The low-temperature properties of the spin S=1/2 ladder with anisotropic
ferromagnetic legs are studied using the continuum limit bosonization approach.
The weak-coupling ground state phase diagram of the model is obtained for a
wide range of coupling constants and several unconventional gapless
''spin-liquid'' phases are shown to exist for ferromagnetic coupling. The
behavior of the ladder system in the vicinity of the ferromagnetic instability
point is discussed in detail.Comment: 11 pages, 4 figure
NOD2 regulates hematopoietic cell function during graft-versus-host disease
Nucleotide-binding oligomerization domain 2 (NOD2) polymorphisms are independent risk factors for Crohn's disease and graft-versus-host disease (GVHD). In Crohn's disease, the proinflammatory state resulting from NOD2 mutations have been associated with a loss of antibacterial function of enterocytes such as paneth cells. NOD2 has not been studied in experimental allogeneic bone marrow transplantation (allo-BMT). Using chimeric recipients with NOD2−/− hematopoietic cells, we demonstrate that NOD2 deficiency in host hematopoietic cells exacerbates GVHD. We found that proliferation and activation of donor T cells was enhanced in NOD-deficient allo-BMT recipients, suggesting that NOD2 plays a role in the regulation of host antigen-presenting cells (APCs). Next, we used bone marrow chimeras in an experimental colitis model and observed again that NOD2 deficiency in the hematopoietic cells results in increased intestinal inflammation. We conclude that NOD2 regulates the development of GVHD through its inhibitory effect on host APC function
Homogenized dynamics of stochastic partial differential equations with dynamical boundary conditions
A microscopic heterogeneous system under random influence is considered. The
randomness enters the system at physical boundary of small scale obstacles as
well as at the interior of the physical medium. This system is modeled by a
stochastic partial differential equation defined on a domain perforated with
small holes (obstacles or heterogeneities), together with random dynamical
boundary conditions on the boundaries of these small holes.
A homogenized macroscopic model for this microscopic heterogeneous stochastic
system is derived. This homogenized effective model is a new stochastic partial
differential equation defined on a unified domain without small holes, with
static boundary condition only. In fact, the random dynamical boundary
conditions are homogenized out, but the impact of random forces on the small
holes' boundaries is quantified as an extra stochastic term in the homogenized
stochastic partial differential equation. Moreover, the validity of the
homogenized model is justified by showing that the solutions of the microscopic
model converge to those of the effective macroscopic model in probability
distribution, as the size of small holes diminishes to zero.Comment: Communications in Mathematical Physics, to appear, 200
Incoherent Interplane Conductivity of kappa-(BEDT-TTF)2Cu[N(CN)2]Br
The interplane optical spectrum of the organic superconductor
kappa-(BEDT-TTF)2Cu[N(CN)2]Br was investigated in the frequency range from 40
to 40,000 cm-1. The optical conductivity was obtained by Kramers-Kronig
analysis of the reflectance. The absence of a Drude peak at low frequency is
consistent with incoherent conductivity but in apparent contradiction to the
metallic temperature dependence of the DC resistivity. We set an upper limit to
the interplane transfer integral of tb = 0.1 meV. A model of defect-assisted
interplane transport can account for this discrepancy. We also assign the
phonon lines in the conductivity to the asymmetric modes of the ET molecule.Comment: 7 pages with embedded figures, submitted to PR
Hole concentration and phonon renormalization in Ca-doped YBa_2Cu_3O_y (6.76 < y < 7.00)
In order to access the overdoped regime of the YBa_2Cu_3O_y phase diagram, 2%
Ca is substituted for Y in YBa_2Cu_3O_y (y = 7.00,6.93,6.88,6.76). Raman
scattering studies have been carried out on these four single crystals.
Measurements of the superconductivity-induced renormalization in frequency
(Delta \omega) and linewidth (\Delta 2\gamma) of the 340 cm^{-1} B_{1g} phonon
demonstrate that the magnitude of the renormalization is directly related to
the hole concentration (p), and not simply the oxygen content. The changes in
\Delta \omega with p imply that the superconducting gap (\Delta_{max})
decreases monotonically with increasing hole concentration in the overdoped
regime, and \Delta \omega falls to zero in the underdoped regime. The linewidth
renormalization \Delta 2\gamma is negative in the underdoped regime, crossing
over at optimal doping to a positive value in the overdoped state.Comment: 18 pages; 5 figures; submitted to Phys. Rev. B Oct. 24, 2002 (BX8292
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