3,363 research outputs found
Successes and Failures of Hospital Ethics Committees: A National Survey of Ethics Committee Chairs
In 1992, the Joint Commission on the Accreditation of Healthcare Organizations (JCAHO) passed a mandate that all its approved hospitals put in place a means for addressing ethical concerns. Although the particular process the hospital uses to address such concernsâethics consultant, ethics forum, ethics committeeâmay vary, the hospital or healthcare ethics committee (HEC) is used most often. In a companion study to that reported here, we found that in 1998 over 90% of U.S. hospitals had ethics committees, compared to just 1% in 1983, and that many have some and a few have sweeping clinical powers in hospitals
Scattering and leapfrogging of vortex rings in a superfluid
The dynamics of vortex ring pairs in the homogeneous nonlinear Schr\"odinger
equation is studied. The generation of numerically-exact solutions of traveling
vortex rings is described and their translational velocity compared to revised
analytic approximations. The scattering behavior of co-axial vortex rings with
opposite charge undergoing collision is numerically investigated for different
scattering angles yielding a surprisingly simple result for its dependence as a
function of the initial vortex ring parameters. We also study the leapfrogging
behavior of co-axial rings with equal charge and compare it with the dynamics
stemming from a modified version of the reduced equations of motion from a
classical fluid model derived using the Biot-Savart law.Comment: 12 pages, 11 figure
Constraints on a Universal IMF from UV to Near-IR Galaxy Luminosity Densities
We obtain constraints on the slope of a universal stellar initial mass
function (IMF) over a range of cosmic star-formation histories (SFH) using
z=0.1 luminosity densities in the range from 0.2 to 2.2 microns. The age-IMF
degeneracy of integrated spectra of stellar populations can be broken for the
Universe as a whole by using direct measurements of (relative) cosmic SFH from
high-redshift observations. These have only marginal dependence on
uncertainties in the IMF, whereas, fitting to local luminosity densities
depends strongly on both cosmic SFH and the IMF. We fit to these measurements
using population synthesis and find the best-fit IMF power-law slope to be
Gamma=1.15+-0.2 (0.5 < M/M_solar < 120). This slope is in good agreement with
the Salpeter IMF slope (Gamma=1.35). A strong upper limit of Gamma<1.7 is
obtained which effectively rules out the Scalo IMF due to its too low fraction
of high-mass stars. This upper limit is at the 99.7% confidence level if we
assume a closed-box chemical evolution scenario and 95% if we assume constant
solar metallicity. Fitting to the H-alpha line luminosity density, we obtain a
best-fit IMF slope in good agreement with that derived from broadband
measurements. Marginalizing over cosmic SFH and IMF slope, we obtain (95% conf.
ranges, h=1): omega_stars = 1.1-2.0 E-3 for the stellar mass density; rho_sfr =
0.7-4.1 E-2 M_solar/yr/Mpc^3 for the star-formation rate density, and; rho_L =
1.2-1.7 E+35 W/Mpc^3 for the bolometric, attenuated, stellar, luminosity
density (0.09-5 microns). Comparing this total stellar emission with an
estimate of the total dust emission implies a relatively modest average
attenuation in the UV (<=1 magnitude at 0.2 microns).Comment: 16 pages, accepted by Ap
The Radio Continuum of the Metal-Deficient Blue Compact Dwarf Galaxy SBS0335-052
We present new Very Large Array observations at five frequencies, from 1.4 to
22GHz, of the extremely low-metallicity blue compact dwarf SBS0335-052. The
radio spectrum shows considerable absorption at 1.49GHz, and a composite
thermal+non-thermal slope. After fitting the data with a variety of models, we
find the best-fitting geometry to be one with free-free absorption
homogeneously intermixed with the emission of both thermal and non-thermal
components. The best-fitting model gives an an emission measure EM ~ 8x10^7pc
cm^{-6} and a diameter of the radio-emitting region D ~17pc. The inferred
density is n_e ~ 2000 cm^{-3}. The thermal emission comes from an ensemble of
\~9000 O7 stars, with a massive star-formation rate (>=5Msun) of 0.13-0.15
yr^{-1}, and a supernova rate of 0.006 yr^{-1}. We find evidence for ionized
gas emission from stellar winds, since the observed Bralpha line flux
significantly exceeds that inferred from the thermal radio emission. The
non-thermal fraction at 5GHz is ~0.7, corresponding to a non-thermal luminosity
of ~2x10^{20} W Hz^{-1}. We attribute the non-thermal radio emission to an
ensemble of compact SN remnants expanding in a dense interstellar medium, and
derive an equipartition magnetic field of ~0.6-1 mG, and a pressure of
\~3x10^{-8}-1x10^{-7} dyne cm^{-2}. If the radio properties of SBS0335-052 are
representative of star formation in extremely low-metallicity environments,
derivations of the star formation rate from the radio continuum in high
redshift primordial galaxies need to be reconsidered. Moreover, photometric
redshifts inferred from ``standard'' spectral energy distributions could be
incorrect.Comment: 25 pages, including 3 figures, accepted for publication in Ap
Diffuse Ionized Gas in the Dwarf Irregular Galaxy DDO 53
The spectral characteristics throughout the dwarf irregular galaxy DDO 53 are
studied. The results are very similar to those for other irregular galaxies:
high excitation and low values of the [SII]/Halpha ratio. The most likely
ionization source is photon leakage from the classical HII regions, without any
other source, although the interstellar medium of the galaxy is quite
perturbed. Moreover, the physical conditions throughout the galaxy do not
change very much because both the photon leakage percentage and the ionization
temperature are very similar. In addition, the determined metal content for two
HII regions indicates that DDO 53 is a low-metallicity galaxy.Comment: 32 pages, 9 figures, 7 tables. AJ, in pres
Swedish consumers' cognitive approaches to nutrition claims and health claims
Introduction and Aim: Studies show frequent use of nutrition claims and health claims in consumers’ choice of food products. The aim of the present study was to investigate how consumers’ thoughts about these claims and food products are affected by various types of food-related experiences. Material and Methods: The data collection comprised 30 individual interviews among Swedish consumers aged 25 to 64 years. Results: The results indicated that participants who expressed special concern for their own and their families’ health were eager to find out the meaning of concepts and statements made. A lack of understanding and lack of credibility of concepts and expressions often caused suspicion of the product. However, in some cases this was counterbalanced by confidence in manufacturers, retailers, and/or the Swedish food legislation. Discussion and Conclusion: To achieve effective written communication of food products’ health-conducive properties on food labels, there is a need to consider the importance many consumers attach to understanding the meaning of concepts and expressions used and the importance of credibility in certain expressions. Consumers’ varying cognitive approaches are suggested as a basis for pre-tests of nutrition claims and health claims
The Two-Communities Theory and Knowledge Utilization
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66698/2/10.1177_000276427902200308.pd
Electrophysiological correlates of high-level perception during spatial navigation
We studied the electrophysiological basis of object recognition by recording scalp\ud
electroencephalograms while participants played a virtual-reality taxi driver game.\ud
Participants searched for passengers and stores during virtual navigation in simulated\ud
towns. We compared oscillatory brain activity in response to store views that were targets or\ud
nontargets (during store search) or neutral (during passenger search). Even though store\ud
category was solely defined by task context (rather than by sensory cues), frontal ...\ud
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Anomalous radio emission from dust in the Helix
A byproduct of experiments designed to map the CMB is the recent detection of
a new component of foreground Galactic emission. The anomalous foreground at ~
10--30 GHz, unexplained by traditional emission mechanisms, correlates with
100um dust emission. We report that in the Helix the emission at 31 GHz and
100um are well correlated, and exhibit similar features on sky images, which
are absent in H\beta. Upper limits on the 250 GHz continuum emission in the
Helix rule out cold grains as candidates for the 31 GHz emission, and provide
spectroscopic evidence for an excess at 31 GHz over bremsstrahlung. We estimate
that the 100um-correlated radio emission, presumably due to dust, accounts for
at least 20% of the 31 GHz emission in the Helix. This result strengthens
previous tentative interpretations of diffuse ISM spectra involving a new dust
emission mechanism at radio frequencies. Very small grains have not been
detected in the Helix, which hampers interpreting the new component in terms of
spinning dust. The observed iron depletion in the Helix favors considering the
identity of this new component to be magnetic dipole emission from hot
ferromagnetic grains. The reduced level of free-free continuum we report also
implies an electronic temperature of Te=4600\pm1200K for the free-free emitting
material, which is significantly lower than the temperature of 9500\pm500K
inferred from collisionally-excited lines (abridged).Comment: Accepted for publication in Ap
Hsp70 in mitochondrial biogenesis
The family of hsp70 (70 kilodalton heat shock protein) molecular chaperones plays an essential and diverse role in cellular physiology, Hsp70 proteins appear to elicit their effects by interacting with polypeptides that present domains which exhibit non-native conformations at distinct stages during their life in the cell. In this paper we review work pertaining to the functions of hsp70 proteins in chaperoning mitochondrial protein biogenesis. Hsp70 proteins function in protein synthesis, protein translocation across mitochondrial membranes, protein folding and finally the delivery of misfolded proteins to proteolytic enzymes in the mitochondrial matrix
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