1,459 research outputs found
Dying Today: Perspectives of the Modern Hospice Worker
From a sociological standpoint, death is relatively difficult to research. While some individuals may describe near-death experiences, the actual act of death cannot be fully known to the living. The purpose of this study is to gain insight into the nature of death and dying in the United States today. This research examines the perspective of modern hospice workers. These individuals work near death on a regular basis and therefore have a privileged understanding of what death is like in US society today. Data consist of ten in-depth interviews with hospice/ palliative-care workers in the Midwestern United States. Respondents were asked questions aimed at gathering data in several distinct areas. The first of these was to outline the modern death context, or social context which encompasses the behaviors and attitudes about death found in society at a given time. The next area of inquiry was on the emotion work required to work near death as well as the emotional labor required to work with individuals and their loved ones in providing end-of-life care. The final area of the findings focused on how the understandings of the respondents changed as they became familiar with the notion of death. Their responses suggest that though the modern death context may not offer extensive experience with death, and that individuals may overcome this unfamiliarity by experiencing death with some frequency. Furthermore, this achieved familiarity seems to help the individual accept death and therefore accept their own mortality
Reversible Thermoset Adhesives
Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry
Dependence of Interstellar Turbulent Pressure on Supernova Rate
Feedback from massive stars is one of the least understood aspects of galaxy
formation. We perform a suite of vertically stratified local interstellar
medium (ISM) simulations in which supernova rates and vertical gas column
densities are systematically varied based on the Schmidt-Kennicutt law. Our
simulations have a sufficiently high spatial resolution (1.95 pc) to follow the
hydrodynamic interactions among multiple supernovae that structure the ISM. At
a given supernova rate, we find that the mean mass-weighted sound speed and
velocity dispersion decrease as the inverse square root of gas density,
indicating that both thermal and turbulent pressures are nearly constant in the
midplane, so the effective equation of state is isobaric. In contrast, across
our four models having supernova rates that range from one to 512 times the
Galactic supernova rate, the mass-weighted velocity dispersion remains in the
range 4-6 km/s. Hence, gas averaged over ~100 pc regions follows an effective
equation of state that is close to isothermal. Simulated H I emission lines
have widths of 10-18 km/s, comparable to observed values. In our highest
supernova rate model, superbubble blow-outs occur, and the turbulent pressure
on large scales is >~4 times higher than the thermal pressure. We find a tight
correlation between the thermal and turbulent pressures averaged over ~100 pc
regions in the midplane of each model, as well as across the four ISM models.
We construct a subgrid model for turbulent pressure based on analytic arguments
and explicitly calibrate it against our stratified ISM simulations. The subgrid
model provides a simple yet physically motivated way to include supernova
feedback in cosmological simulations.Comment: 13 pages incl. 8 figures; accepted for publication in ApJ; contains a
new model of starburst galaxy showing superbubble blow-ou
The Origin and Kinematics of Cold Gas in Galactic Winds: Insight from Numerical Simulations
We study the origin of Na I absorbing gas in ultraluminous infrared galaxies
motivated by the recent observations by Martin of extremely superthermal
linewidths in this cool gas. We model the effects of repeated supernova
explosions driving supershells in the central regions of molecular disks with
M_d=10^10 M_\sun, using cylindrically symmetric gas dynamical simulations run
with ZEUS-3D. The shocked swept-up shells quickly cool and fragment by
Rayleigh-Taylor instability as they accelerate out of the dense, stratified
disks. The numerical resolution of the cooling and compression at the shock
fronts determines the peak shell density, and so the speed of Rayleigh-Taylor
fragmentation. We identify cooled shells and shell fragments as Na I absorbing
gas and study its kinematics. We find that simulations with a numerical
resolution of \le 0.2 pc produce multiple Rayleigh-Taylor fragmented shells in
a given line of sight. We suggest that the observed wide Na I absorption lines,
= 320 \pm 120 km s^-1 are produced by these multiple fragmented shells
traveling at different velocities. We also suggest that some shell fragments
can be accelerated above the observed average terminal velocity of 750 km s^-1
by the same energy-driven wind with an instantaneous starburst of \sim 10^9
M_\sun. The bulk of mass is traveling with the observed average shell velocity
330 \pm 100 km s^-1. Our results show that an energy-driven bubble causing
Rayleigh-Taylor instabilities can explain the kinematics of cool gas seen in
the Na I observations without invoking additional physics relying primarily on
momentum conservation, such as entrainment of gas by Kelvin-Helmholtz
instabilities, ram pressure driving of cold clouds by a hot wind, or radiation
pressure acting on dust. (abridged)Comment: 65 pages, 22 figures, accepted by Astrophys. J. Changes during
refereeing focused on context and comparison to observation
Black Hole growth and AGN obscuration by instability-driven inflows in high-redshift disk galaxies fed by cold streams
Disk galaxies at high redshift have been predicted to maintain high gas
surface densities due to continuous feeding by intense cold streams leading to
violent gravitational instability, transient features and giant clumps.
Gravitational torques between the perturbations drive angular momentum out and
mass in, and the inflow provides the energy for keeping strong turbulence. We
use analytic estimates of the inflow for a self-regulated unstable disk at a
Toomre stability parameter Q~1, and isolated galaxy simulations capable of
resolving the nuclear inflow down to the central parsec. We predict an average
inflow rate ~10 Msun/yr through the disk of a 10^11 Msun galaxy, with
conditions representative of z~2 stream-fed disks. The inflow rate scales with
disk mass and (1+z)^{3/2}. It includes clump migration and inflow of the
smoother component, valid even if clumps disrupt. This inflow grows the bulge,
while only a fraction ~ 10^-3 of it needs to accrete onto a central black hole
(BH), in order to obey the observed BH-bulge relation. A galaxy of 10^11 Msun
at z~2 is expected to host a BH of ~10^8 Msun, accreting on average with
moderate sub-Eddington luminosity L_X ~ 10^42-43 erg/s, accompanied by brighter
episodes when dense clumps coalesce. We note that in rare massive galaxies at
z~6, the same process may feed 10^9 Msun BH at the Eddington rate. High central
gas column densities can severely obscure AGN in high-redshift disks, possibly
hindering their detection in deep X-ray surveys.Comment: ApJL in pres
Dietary quality in a sample of adults with type 2 diabetes mellitus in Ireland; a cross-sectional case control study
BACKGROUND A number of dietary quality indices (DQIs) have been developed to assess the quality of dietary intake. Analysis of the intake of individual nutrients does not reflect the complexity of dietary behaviours and their association with health and disease. The aim of this study was to determine the dietary quality of individuals with type 2 diabetes mellitus (T2DM) using a variety of validated DQIs. METHODS In this cross-sectional analysis of 111 Caucasian adults, 65 cases with T2DM were recruited from the Diabetes Day Care Services of St. Columcille's and St. Vincent's Hospitals, Dublin, Ireland. Forty-six controls did not have T2DM and were recruited from the general population. Data from 3-day estimated diet diaries were used to calculate 4 DQIs. RESULTS Participants with T2DM had a significantly lower score for consumption of a Mediterranean dietary pattern compared to the control group, measured using the Mediterranean Diet Score (Range 0-9) and the Alternate Mediterranean Diet Score (Range 0-9) (mean ± SD) (3.4 ± 1.3 vs 4.8 ± 1.8, P < 0.001 and 3.3 ± 1.5 vs 4.2 ± 1.8, P = 0.02 respectively). Participants with T2DM also had lower dietary quality than the control population as assessed by the Healthy Diet Indicator (Range 0-9) (T2DM; 2.6 ± 2.3, control; 3.3 ± 1.1, P = 0.001). No differences between the two groups were found when dietary quality was assessed using the Alternate Healthy Eating Index. Micronutrient intake was assessed using the Micronutrient Adequacy Score (Range 0-8) and participants with T2DM had a significantly lower score than the control group (T2DM; 1.6 ± 1.4, control; 2.3 ± 1.4, P = 0.009). When individual nutrient intakes were assessed, no significant differences were observed in macronutrient intake. CONCLUSION Overall, these findings demonstrate that T2DM was associated with a lower score when dietary quality was assessed using a number of validated indices.This study was funded by Science Foundation Ireland (Grant number 08/RFP/BMT1342)
The stellar mass spectrum from non-isothermal gravoturbulent fragmentation
Identifying the processes that determine the initial mass function of stars
(IMF) is a fundamental problem in star formation theory. One of the major
uncertainties is the exact chemical state of the star forming gas and its
influence on the dynamical evolution. Most simulations of star forming clusters
use an isothermal equation of state (EOS). However, theoretical predictions and
observations suggest that the effective polytropic exponent gamma in the EOS
varies with density.
We address these issues and study the effect of a piecewise polytropic EOS on
the formation of stellar clusters in turbulent, self-gravitating molecular
clouds using three-dimensional, smoothed particle hydrodynamics simulations. To
approximate the results of published predictions of the thermal behavior of
collapsing clouds, we increase the polytropic exponent gamma from 0.7 to 1.1 at
some chosen density n_c, which we vary. The change of thermodynamic state at
n_c selects a characteristic mass scale for fragmentation M_ch, which we relate
to the peak of the observed IMF. Our investigation generally supports the idea
that the distribution of stellar masses depends mainly on the thermodynamic
state of the star-forming gas. The thermodynamic state of interstellar gas is a
result of the balance between heating and cooling processes, which in turn are
determined by fundamental atomic and molecular physics and by chemical
abundances. Given the abundances, the derivation of a characteristic stellar
mass can thus be based on universal quantities and constants.Comment: 13 pages, 7 figures, accepted by A&
Simulation of radiation driven wind from disc galaxies
We present 2-D hydrodynamic simulation of rotating galactic winds driven by
radiation. We study the structure and dynamics of the cool and/or warm
component( K) which is mixed with dust. We have taken into
account the total gravity of a galactic system that consists of a disc, a bulge
and a dark matter halo. We find that the combined effect of gravity and
radiation pressure from a realistic disc drives the gas away to a distance of
kpc in Myr for typical galactic parameters. The outflow
speed increases rapidly with the disc Eddington parameter ) for . We find that the rotation speed of
the outflowing gas is km s. The wind is confined in a
cone which mostly consist of low angular momentum gas lifted from the central
region.Comment: 10 pages, 11 figures, Accepted for publication in MNRA
Survival of Star-Forming Giant Clumps in High-Redshift Galaxies
We investigate the effects of radiation pressure from stars on the survival
of the star-forming giant clumps in high-redshift massive disc galaxies, during
the most active phase of galaxy formation. The clumps, typically of mass
~10^8-10^9 Msun and radius ~0.5-1, are formed in the turbulent gas-rich discs
by violent gravitational instability and then migrate into a central bulge in
~10 dynamical times. We show that the survival or disruption of these clumps
under the influence of stellar feedback depends critically on the rate at which
they form stars. If they convert a few percent of their gas mass to stars per
free-fall time, as observed for all local star-forming systems and implied by
the Kennicutt-Schmidt law, they cannot be disrupted. Only if clumps convert
most of their mass to stars in a few free-fall times can feedback produce
significant gas expulsion. We consider whether such rapid star formation is
likely in high-redshift giant clumps.Comment: 11 pages, 1 figure, accepted to MNRA
Algorithm to Diagnose Leaks or Blockages Downstream of the Secondary Air Injection Reaction (SAIR) Pressure Sensor
A control module and method for an exhaust system of an engine can include a secondary air intake (SAI) pressure module that monitors SAI pressure. An accumulation module can accumulate an SAI string length based on the monitored SAI pressure. A calculation module can determine an average SAI string length based on the accumulated SAI string length. A determination module can determine an operating characteristic of the vehicle exhaust based on the average SAI string length
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