2,674 research outputs found
Comparison of stroke volume measurement between non-invasive bioreactance and esophageal Doppler in patients undergoing major abdominal-pelvic surgery
PURPOSE:
Bioreactance is a non-invasive technology for measuring stroke volume (SV) in the operating room and critical care setting. We evaluated how the NICOM® bioreactance device performed against the CardioQ® esophageal Doppler monitor in patients undergoing major abdominal–pelvic surgery, focusing on the effect of different hemodynamic interventions.
METHODS:
SVNICOM and SVODM were simultaneously measured intraoperatively, including before and after interventions including fluid challenge, vasopressor boluses, peritoneal gas insufflation/removal, and Trendelenburg/reverse Trendelenburg patient positioning.
RESULTS:
A total of 768 values were collected from 21 patients. Pre- and post-intervention measures were recorded on 155 occasions. Bland–Altman analysis revealed a bias of 8.6 ml and poor precision with wide limits of agreement (54 and −37 ml) and a percentage error of 50.6%. No improvement in precision was detected after taking into account repeated measurements for each patient (bias: 8 ml; limits of agreement: 74 and −59 ml). Concordance between changes in SVNICOM and SVODM before and after interventions was also poor: 78.7% (all measures), 82.4% (after vasopressor administration), and 74.3% (after fluid challenge). Using Doppler SV as the reference technique, the area under the receiver operating characteristic curve assessing the ability of the NICOM device to predict fluid responsiveness was 0.81 (0.7–0.9).
CONCLUSIONS:
In patients undergoing major abdomino-pelvic surgery, SV values obtained by NICOM showed neither clinically or statistically acceptable agreement with those obtained by esophageal Doppler. Although, in the setting of this study, bioreactance technology cannot reliably replace esophageal Doppler monitoring, its accuracy for predicting fluid responsiveness was higher, up to approximately 80%
Deuteron photo-disintegration with polarised photons in the energy range 30 - 50 MeV
The reaction d(\vec\gamma,np) has been studied using the tagged and polarised
LADON gamma ray beam at an energy 30 - 50 MeV to investigate the existence of
narrow dibaryonic resonances recently suggested from the experimental
measurements in a different laboratory. The beam was obtained by Compton
back-scattering of laser light on the electrons of the storage ring ADONE.
Photo-neutron yields were measured at five neutron angle \vartheta_n = 22,
55.5, 90, 125 and 157 degrees in the center of mass system.Our results do not
support the existence of such resonances.Comment: 16 pages, Latex, 22 figures, 1 table. Nucl. Phys. A to appea
The build-up of the colour-magnitude relation in galaxy clusters since z~0.8
Using galaxy clusters from the ESO Distant Cluster Survey, we study how the
distribution of galaxies along the colour-magnitude relation has evolved since
z~0.8. While red-sequence galaxies in all these clusters are well described by
an old, passively evolving population, we confirm our previous finding of a
significant evolution in their luminosity distribution as a function of
redshift. When compared to galaxy clusters in the local Universe, the high
redshift EDisCS clusters exhibit a significant "deficit" of faint red galaxies.
Combining clusters in three different redshift bins, and defining as `faint'
all galaxies in the range 0.4 > L/L* > 0.1, we find a clear decrease in the
luminous-to-faint ratio of red galaxies from z~0.8 to z~0.4. The amount of such
a decrease appears to be in qualitative agreement with predictions of a model
where the blue bright galaxies that populate the colour-magnitude diagram of
high redshift clusters, have their star formation suppressed by the hostile
cluster environment. Although model results need to be interpreted with
caution, our findings clearly indicate that the red-sequence population of
high-redshift clusters does not contain all progenitors of nearby red-sequence
cluster galaxies. A significant fraction of these must have moved onto the
red-sequence below z~0.8.Comment: 15 pages, 10 figures, accepted for publication in MNRA
Polarization Asymmetry In The Photodisintegration Of The Deuteron
The reaction ²(γ,p)n has been studied using a monochromatic and polarized gamma ray beam at energies E(γ)=19.8, 29.0, 38.6, and 60.8 MeV. The beam of an intensity ∼4×10⁵ γ/sec was obtained by Compton back scattering of mode-locked laser light off electron bunches in the Adone storage ring. Photoneutron yields were measured at nine neutron angles thetan≃15, 30, 45, 60, 90, 120, 135, 150, and 165 deg in the center of mass (c.m.) for E(γ)=19.8, 29.0, and 38.6 MeV, and at thetan≃30, 60, 90, 120, and 150 deg c.m. for E(γ)=60.8 MeV. The polarization independent component Iₒ(theta) of the differential cross section and the polarization dependent component PI₁(theta) were deduced and the angular distribution of the azimuthal asymmetry factor Σ(theta)=I₁(theta)/Iₒ(theta) was obtained. An extensive comparison with theory has been carried out and the inclusion of corrections due to meson exchange currents and to Δ-isobar configurations have been shown to be mandatory at energies E(γ)≳40 MeV. Theoretical and experimental implications of intermediate energy deuteron photo- disintegration studies are discussed in some detail
Polarization Asymmetry In The Photodisintegration Of The Deuteron
The reaction ²(γ,p)n has been studied using a monochromatic and polarized gamma ray beam at energies E(γ)=19.8, 29.0, 38.6, and 60.8 MeV. The beam of an intensity ∼4×10⁵ γ/sec was obtained by Compton back scattering of mode-locked laser light off electron bunches in the Adone storage ring. Photoneutron yields were measured at nine neutron angles thetan≃15, 30, 45, 60, 90, 120, 135, 150, and 165 deg in the center of mass (c.m.) for E(γ)=19.8, 29.0, and 38.6 MeV, and at thetan≃30, 60, 90, 120, and 150 deg c.m. for E(γ)=60.8 MeV. The polarization independent component Iₒ(theta) of the differential cross section and the polarization dependent component PI₁(theta) were deduced and the angular distribution of the azimuthal asymmetry factor Σ(theta)=I₁(theta)/Iₒ(theta) was obtained. An extensive comparison with theory has been carried out and the inclusion of corrections due to meson exchange currents and to Δ-isobar configurations have been shown to be mandatory at energies E(γ)≳40 MeV. Theoretical and experimental implications of intermediate energy deuteron photo- disintegration studies are discussed in some detail
Congested traffic equilibria and degenerate anisotropic PDEs
Congested traffic problems on very dense networks lead, at the limit, to minimization problems posed on measures on curves as shown in Baillon and Carlier (Netw. Heterogenous Media 7: 219--241, 2012). Here, we go one step further by showing that these problems can be reformulated in terms of the minimization of an integral functional over a set of vector fields with prescribed divergence. We prove a Sobolev regularity result for their minimizers despite the fact that the Euler-Lagrange equation of the dual is highly degenerate and anisotropic. This somehow extends the analysis of Brasco et al. (J. Math. Pures Appl. 93: 652--671, 2010) to the anisotropic case
Interstellar dust in the BOOMERanG maps
Interstellar dust (ISD) emission is present in the mm-wave maps obtained by the BOOMERanG experiment at intermediate and high Galactic latitudes. We find that, while being sub-dominant at the lower frequencies (90,150, 240 GHz), thermal emission from ISD is dominant at 410 GHz, and is well correlated with the IRAS map at 100 µm. We find also that the angular power spectrum of ISD fluctuations at 410 GHz is a power law, and its level is negligible with respect to the angular power spectrum of the Cosmic Microwave Background (CMB) at 90 and 150 GHz
Images of the Early Universe from the BOOMERanG experiment
The CMB is the fundamental tool to study the properties of the early universe and of the
universe at large scales. In the framework of the Hot Big Bang model, when we look to
the CMB we look back in time to the end of the plasma era, at a redshift ~ 1000, when
the universe was ~ 50000 times younger, ~ 1000 times hotter and ~ 10^9 times denser
than today. The image of the CMB can be used to study the physical processes there, to
infer what happened before, and also to study the background geometry of our Universe
BFORE: The B-mode Foreground Experiment
The B-mode Foreground Experiment (BFORE) is a proposed NASA balloon project
designed to make optimal use of the sub-orbital platform by concentrating on
three dust foreground bands (270, 350, and 600 GHz) that complement
ground-based cosmic microwave background (CMB) programs. BFORE will survey ~1/4
of the sky with 1.7 - 3.7 arcminute resolution, enabling precise
characterization of the Galactic dust that now limits constraints on inflation
from CMB B-mode polarization measurements. In addition, BFORE's combination of
frequency coverage, large survey area, and angular resolution enables science
far beyond the critical goal of measuring foregrounds. BFORE will constrain the
velocities of thousands of galaxy clusters, provide a new window on the cosmic
infrared background, and probe magnetic fields in the interstellar medium. We
review the BFORE science case, timeline, and instrument design, which is based
on a compact off-axis telescope coupled to >10,000 superconducting detectors.Comment: 7 pages, 4 figures, conference proceedings published in Journal of
Low Temperature Physic
Foregrounds in the BOOMERANG-LDB data: a preliminary rms analysis
We present a preliminary analysis of the BOOMERanG LDB maps, focused on
foregrounds. BOOMERanG detects dust emission at moderately low galactic
latitudes () in bands centered at 90, 150, 240, 410 GHz. At higher
Galactic latitudes, we use the BOOMERanG data to set conservative upper limits
on the level of contamination at 90 and 150 GHz. We find that the mean square
signal correlated with the IRAS/DIRBE dust template is less than 3% of the mean
square signal due to CMB anisotropy
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