746 research outputs found
OH yields from the CH3CO+O-2 reaction using an internal standard
Laser flash photolysis of CH3C(O)OH at 248 nm was used to create equal zero time yields of CH3CO and OH. The absolute OH yield from the CH3CO + O2 (+M) reaction was determined by following the OH temporal profile using the zero time
OH concentration as an internal standard. The OH yield from CH3CO + O2 (+M) was observed to decrease with increasing pressure with an extrapolated zero pressure yield
close to unity (1.1 ± 0.2, quoted uncertainties correspond to 95% confidence limits). The results are in quantitative agreement with those obtained from 248 nm acetone
photolysis in the presence of O2
The Distances of SNR W41 and overlapping HII regions
New HI images from the VLA Galactic Plane Survey show prominent absorption
features associated with the supernovae remnant G23.3-0.3 (SNR W41). We
highlight the HI absorption spectra and the CO emission spectra of eight
small regions on the face of W41, including four HII regions, three non-thermal
emission regions and one unclassified region. The maximum velocity of
absorption for W41 is 782 km/s and the CO cloud at radial velocity
955 km/s is behind W41. Because an extended TeV source, a diffuse X-ray
enhancement and a large molecular cloud at radial velocity 775 km/s are
also projected at the center of W41, these yield the kinematic distance of 3.9
to 4.5 kpc for W41. For HII regions, our analyses reveal that both G23.42-0.21
and G23.07+0.25 are at the far kinematic distances (9.9 kpc and
10.6 kpc respectively) of their recombination-line velocities (1030.5 km/s
and 89.62.1 km/s respectively), G23.07-0.37 is at the near kinematic
distance (4.40.3 kpc) of its recombination-line velocity (82.72.0
km/s), and G23.27-0.27 is probably at the near kinematic distance (4.10.3
kpc) of its recombination-line velocity (76.10.6 km/s).Comment: 11 pages, 3 figs., 2 tables, accepted by A
Quality Improvement Cycles that Reduced Waiting Times at Tshwane District Hospital Emergency Department
Background: Tshwane District Hospital (TDH) is a level-one hospital, delivering services in the centre of Pretoria since February 2006. It is unique in location, being only 100 meters away from the tertiary hospital, Pretoria Academic Hospital (PAH). In South Africa, public sector emergency units are under enormous pressure with large patient numbers, understaffing and poor resources. TDH Emergency Department (ED) is a typical example. An average of 3 900 patients per month visited this ED in 2006. Recurrent complaints and dissatisfaction shown by the patients about prolonged waiting times before consulting the medical practitioners (MPs) in the ED were one of the initial challenges faced by the newly established hospital. It was decided to undertake quality improvement (QI) cycles to analyse and improve the situation, using waiting time as a measure of improvement. Methods: A QI team was chosen to conduct two QI cycles. The allocated time for QI cycle 1 was from May to August 2006 and for QI cycle 2 from September to December 2006. A total of 150 waiting times of stable and unstable patients were evaluated. Fifty waiting times were recorded over a span of 24 hours for each data collection in May, September and December 2006. Waiting time was defined as the time from arrival of the patient in the unit until the start of the consultation by the MP. Surveys were done in May and September to analyse the problems causing prolonged waiting times. The implemented change included instituting a functional triage system, improvement of the process of up- and down-referrals to and from the tertiary hospital, easy access to stock, reorganisation of doctors' duty roster, reorganisation of the academic programme, announcement on waiting time to patients, nurses carrying out minor procedures and availability of reference books.
Results: The median waiting times for stable patients were as follows: May 2006: 545 minutes (range 200 to 1 260), September 2006: 230 minutes (range 15 to 480) and December 2006: 89 minutes (range 15 to 230). There was a significant difference
among these waiting times for May, September and December 2006 (p < 0.001; Kruskal-Wallis H test). The median waiting times for unstable patients were as follows: May 2006: zero minutes (range 0 to 30), September 2006: zero minutes (range 0 to 3)
and December 2006: 0.5 minutes (range 0 to 2). There was no difference among the waiting times for unstable patients for May, September and December 2006 (p = 0.90; Kruskal-Wallis H test). Conclusion: This QI exercise identified problems causing prolonged waiting time for stable patients at TDH ED. It rectified most of the identified problems. However, goals regarding registration and laboratory delays could not be successfully achieved. This study showed the significance of QI cycles in improving waiting times for stable patients at TDH ED without any additional financial or human resources. This was done without compromising the time taken to see unstable patients. South African Family Practice Vol. 50 (6) 2008: pp. 43-43
A Magellanic Origin for the Warp of the Galaxy
We show that a Magellanic Cloud origin for the warp of the Milky Way can
explain most quantitative features of the outer HI layer recently identified by
Levine, Blitz & Heiles (2005). We construct a model similar to that of Weinberg
(1998) that produces distortions in the dark matter halo, and we calculate the
combined effect of these dark-halo distortions and the direct tidal forcing by
the Magellanic Clouds on the disk warp in the linear regime. The interaction of
the dark matter halo with the disk and resonances between the orbit of the
Clouds and the disk account for the large amplitudes observed for the vertical
m=0,1,2 harmonics. The observations lead to six constraints on warp forcing
mechanisms and our model reasonably approximates all six. The disk is shown to
be very dynamic, constantly changing its shape as the Clouds proceed along
their orbit. We discuss the challenges to MOND placed by the observations.Comment: 4 pages, 3 figures, submitted to ApJ Letters. Additional graphics, 3d
visualizations and movies available at
http://www.astro.umass.edu/~weinberg/lm
Gender and displacement in Jaffna, Sri Lanka
This report presents the preliminary results of a household survey of internally displaced persons (IDPs) in Jaffna District in Northern Province, one of the areas that still has a large IDP population. The main focus of this survey conducted in October 2020 employing Covid-19 safety protocols was to examine the gendered experiences arising from protracted displacements spanning over three decades. The survey covered 220 households (182 male-headed and 38 female-headed), which accounts for 54.3 per cent of the total IDP households in the Jaffna District.
Among other topics, the survey gathered data on the respondents’ current living conditions, finances, asset ownership, safety and security concerns, access to services, social networks and relationship with other IDPs and the host community, and water, sanitation and hygiene issues they face. It also gathered data on the respondents’ pre-displacement experiences to compare that with their current lives, in order to examine the role of displacement in gendered issues they face
Unusually Luminous Giant Molecular Clouds in the Outer Disk of M33
We use high spatial resolution (~7pc) CARMA observations to derive detailed
properties for 8 giant molecular clouds (GMCs) at a galactocentric radius
corresponding to approximately two CO scale lengths, or ~0.5 optical radii
(r25), in the Local Group spiral galaxy M33. At this radius, molecular gas
fraction, dust-to-gas ratio and metallicity are much lower than in the inner
part of M33 or in a typical spiral galaxy. This allows us to probe the impact
of environment on GMC properties by comparing our measurements to previous data
from the inner disk of M33, the Milky Way and other nearby galaxies. The outer
disk clouds roughly fall on the size-linewidth relation defined by
extragalactic GMCs, but are slightly displaced from the luminosity-virial mass
relation in the sense of having high CO luminosity compared to the inferred
virial mass. This implies a different CO-to-H2 conversion factor, which is on
average a factor of two lower than the inner disk and the extragalactic
average. We attribute this to significantly higher measured brightness
temperatures of the outer disk clouds compared to the ancillary sample of GMCs,
which is likely an effect of enhanced radiation levels due to massive star
formation in the vicinity of our target field. Apart from brightness
temperature, the properties we determine for the outer disk GMCs in M33 do not
differ significantly from those of our comparison sample. In particular, the
combined sample of inner and outer disk M33 clouds covers roughly the same
range in size, linewidth, virial mass and CO luminosity than the sample of
Milky Way GMCs. When compared to the inner disk clouds in M33, however, we find
even the brightest outer disk clouds to be smaller than most of their inner
disk counterparts. This may be due to incomplete sampling or a potentially
steeper cloud mass function at larger radii.Comment: Accepted for Publication in ApJ; 7 pages, 4 figure
Constraints on the galactic distribution of cosmic rays from the COS-B gamma-ray data
The diffuse component of the galactic high energy gamma rays results mainly from the interaction of CR nuclei and electrons with the nuclei of the interstellar gas. An additional contribution is obtained from the interaction of CR electrons with the interstellar photons through the inverse-Compton (IC) process. Gamma ray astronomy therefore offers an excellent means to study the distribution of CR particles throughout the Galaxy, but it is essential to know the distribution of the target interstellar gas particles, the major constituents being atomic and molecular hydrogen. Large scale millimeter wave surveys of the CO molecule covering more than half of the Milky Way, obtained with the Columbia 1.2 m telescopes, are currently available and are used to trace the H2; the COS-B observations have sufficient resolution and sensitivity to constrain the relation between the integrated CO line intensity and the molecular hydrogen column density
High-Resolution Measurements of the Dark Matter Halo of NGC 2976: Evidence for a Shallow Density Profile
We have obtained two-dimensional velocity fields of the dwarf spiral galaxy
NGC 2976 in Halpha and CO. The high spatial (~75 pc) and spectral (13 km/s and
2 km/s, respectively) resolution of these observations, along with our
multicolor optical and near-infrared imaging, allow us to measure the shape of
the density profile of the dark matter halo with good precision. We find that
the total (baryonic plus dark matter) mass distribution of NGC 2976 follows a
rho_tot ~ r^(-0.27 +/- 0.09) power law out to a radius of 1.8 kpc, assuming
that the observed radial motions provide no support. The density profile
attributed to the dark halo is even shallower, consistent with a nearly
constant density of dark matter over the entire observed region. A maximal disk
fit yields an upper limit to the K-band stellar mass-to-light ratio (M*/L_K) of
0.09^{+0.15}_{-0.08} M_sun/L_sun,K (including systematic uncertainties), with
the caveat that for M*/L_K > 0.19 M_sun/L_sun,K the dark matter density
increases with radius, which is unphysical. Assuming 0.10 M_sun/L_sun,K <
M*/L_K < 0.19 M_sun/L_sun,K, the dark matter density profile lies between
rho_dm ~ r^-0.17 and rho_dm ~ r^-0.01. Therefore, independent of any
assumptions about the stellar disk or the functional form of the density
profile, NGC 2976 does not contain a cuspy dark matter halo. We also
investigate some of the systematic effects that can hamper rotation curve
studies, and show that 1) longslit rotation curves are far more vulnerable to
systematic errors than two-dimensional velocity fields, 2) NGC 2976 contains
large radial motions at small radii, and 3) the Halpha and CO velocity fields
of NGC 2976 agree within their uncertainties. [slightly abridged]Comment: 30 pages, 4 tables, 13 figures (7 in color; Figures 1 and 3 are
low-resolution to save space). Accepted for publication in ApJ. Version with
full-resolution figures available at
http://astro.berkeley.edu/~bolatto/ngc2976rotation.ps (46 MB
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