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10-minute consultation - Gastro-oesophageal reflux disease
Copyright © 2002, BMJJanusz Jankowski, Roger Jones, Brendan Delaney and John Den
Freshly Formed Dust in the Cassiopeia A Supernova Remnant as Revealed by the Spitzer Space Telescope
We performed Spitzer Infrared Spectrograph mapping observations covering
nearly the entire extent of the Cassiopeia A supernova remnant (SNR), producing
mid-infrared (5.5-35 micron) spectra every 5-10". Gas lines of Ar, Ne, O, Si, S
and Fe, and dust continua were strong for most positions. We identify three
distinct ejecta dust populations based on their continuum shapes. The dominant
dust continuum shape exhibits a strong peak at 21 micron. A line-free map of 21
micron-peak dust made from the 19-23 micron range closely resembles the [Ar
II], [O IV], and [Ne II] ejecta-line maps implying that dust is freshly formed
in the ejecta. Spectral fitting implies the presence of SiO2, Mg
protosilicates, and FeO grains in these regions. The second dust type exhibits
a rising continuum up to 21 micron and then flattens thereafter. This ``weak 21
micron'' dust is likely composed of Al2O3 and C grains. The third dust
continuum shape is featureless with a gently rising spectrum and is likely
composed of MgSiO3 and either Al2O3 or Fe grains. Using the least massive
composition for each of the three dust classes yields a total mass of 0.02
Msun. Using the most-massive composition yields a total mass of 0.054 Msun. The
primary uncertainty in the total dust mass stems from the selection of the dust
composition necessary for fitting the featureless dust as well as 70 micron
flux. The freshly formed dust mass derived from Cas A is sufficient from SNe to
explain the lower limit on the dust masses in high redshift galaxies.Comment: 8 figures: Accepted for the publication in Ap
Time Variability in the X-ray Nebula Powered by Pulsar B1509-58
We use new and archival Chandra and ROSAT data to study the time variability
of the X-ray emission from the pulsar wind nebula (PWN) powered by PSR B1509-58
on timescales of one week to twelve years. There is variability in the size,
number, and brightness of compact knots appearing within 20" of the pulsar,
with at least one knot showing a possible outflow velocity of ~0.6c (assuming a
distance to the source of 5.2 kpc). The transient nature of these knots may
indicate that they are produced by turbulence in the flows surrounding the
pulsar. A previously identified prominent jet extending 12 pc to the southeast
of the pulsar increased in brightness by 30% over 9 years; apparent outflow of
material along this jet is observed with a velocity of ~0.5c. However, outflow
alone cannot account for the changes in the jet on such short timescales.
Magnetohydrodynamic sausage or kink instabilities are feasible explanations for
the jet variability with timescale of ~1.3-2 years. An arc structure, located
30"-45" north of the pulsar, shows transverse structural variations and appears
to have moved inward with a velocity of ~0.03c over three years. The overall
structure and brightness of the diffuse PWN exterior to this arc and excluding
the jet has remained the same over the twelve year span. The photon indices of
the diffuse PWN and possibly the jet steepen with increasing radius, likely
indicating synchrotron cooling at X-ray energies.Comment: accepted to ApJ, 14 pages, 8 figure
Adapting primary care for new migrants: a formative assessment
Background: Immigration rates have increased recently in the UK. Migrant patients may have
particular needs that are inadequately met by existing primary care provision. In the absence of
national guidance, local adaptations are emerging in response to these new demands.
Aim: To formatively assess the primary care services offered to new migrants and the ways in which
practitioners and practices are adapting to meet need.
Design & setting: Online survey and case studies of current practice across primary care in the UK.
Case studies were selected from mainstream and specialist general practice as well as primary care
provision in the third sector.
Method: Non-probability sample survey of primary care practitioners (n = 70) with descriptive
statistical analysis. Qualitative case studies (n = 8) selected purposively; in-depth exploration of
organisational and practitioner adaptations to services. Analysis is structured around the principles
of equitable care.
Results: Survey results indicated that practitioners focused on working with communities and
external agencies and adapting processes of, for example, screening, vaccination, and health
checks. Lack of funding was cited most frequently as a barrier to service development (n = 51;
73%). Case studies highlighted the prominence partnership working and of an organisational and
practitioner focus on equitable care. Adaptations centred on addressing wider social determinants,
trauma, and violence, and additional individual needs; and on delivering culturally-competent care.
Conclusion: Despite significant resource constraints, some primary care services are adapting to
the needs of new migrants. Many adapted approaches can be characterised as equity-oriented
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