2,154 research outputs found
The surgical workforce shortage and successes in retaining surgical trainees in Ethiopia: a professional survey
BACKGROUND: Medical workforce shortages represent a major challenge in low- and middle-income countries, including those in Africa. Despite this, there is a dearth of information regarding the location and practice of African surgeons following completion of their training. In response to the call by the WHO Global Code of Practice on the International Recruitment of Health Personnel for a sound evidence base regarding patterns of practice and migration of the health workforce, this study describes the current place of residence, practice and setting of Ethiopian surgical residency graduates since commencement of their surgical training in Ethiopia or in Cuba. METHODS: This study presents data from a survey of all Ethiopian surgical residency training graduates since the programme’s inception in 1985. RESULTS: A total of 348 Ethiopians had undergone surgical training in Ethiopia or Cuba since 1985; data for 327 (94.0 %) of these surgeons were collected and included in the study. The findings indicated that 75.8 % of graduates continued to practice in Ethiopia, with 80.9 % of these practicing in the public sector. Additionally, recent graduates were more likely to remain in Ethiopia and work within the public sector. The average total number of surgeons per million inhabitants in Ethiopia was approximately three and 48.0 % of Ethiopian surgeons practiced in Addis Ababa. CONCLUSIONS: Ethiopian surgeons are increasingly likely to remain in Ethiopia and to practice in the public sector. Nevertheless, Ethiopia continues to suffer from a drastic surgical workforce shortage that must be addressed through increased training capacity and strategies to combat emigration and attrition
Observations of M87 and Hydra A at 90 GHz
This paper presents new observations of the AGNs M87 and Hydra A at 90 GHz
made with the MUSTANG bolometer array on the Green Bank Telescope at 8.5"
resolution. A spectral analysis is performed combining this new data and
archival VLA data on these objects at longer wavelengths. This analysis can
detect variations in spectral index and curvature expected from energy losses
in the radiating particles. M87 shows only weak evidence for steepening of the
spectrum along the jet suggesting either re-acceleration of the relativistic
particles in the jet or insufficient losses to affect the spectrum at 90 GHz.
The jets in Hydra A show strong steepening as they move from the nucleus
suggesting unbalanced losses of the higher energy relativistic particles. The
difference between these two sources may be accounted for by the different
lengths over which the jets are observable, 2 kpc for M87 and 45 kpc for Hydra
A.Comment: 11 pages, submitted to Ap
The Radio - 2 mm Spectral Index of the Crab Nebula Measured with GISMO
We present results of 2 mm observations of the Crab Nebula, obtained using
the Goddard-IRAM Superconducting 2 Millimeter Observer (GISMO) bolometer camera
on the IRAM 30 m telescope. Additional 3.3 mm observations with the MUSTANG
bolometer array on the Green Bank Telescope are also presented. The integrated
2 mm flux density of the Crab Nebula provides no evidence for the emergence of
a second synchrotron component that has been proposed. It is consistent with
the radio power law spectrum, extrapolated up to a break frequency of
log(nu_{b} [GHz]) = 2.84 +/- 0.29 or nu_{b} = 695^{+651}_{-336} GHz. The Crab
Nebula is well-resolved by the ~16.7" beam (FWHM) of GISMO. Comparison to radio
data at comparable spatial resolution enables us to confirm significant spatial
variation of the spectral index between 21 cm and 2 mm. The main effect is a
spectral flattening in the inner region of the Crab Nebula, correlated with the
toroidal structure at the center of the nebula that is prominent in the near-IR
through X-ray regime.Comment: Accepted for publication in the Ap
90GHz and 150GHz observations of the Orion M42 region. A sub-millimeter to radio analysis
We have used the new 90GHz MUSTANG camera on the Robert C. Byrd Green Bank
Telescope (GBT) to map the bright Huygens region of the star-forming region M42
with a resolution of 9" and a sensitivity of 2.8mJy/beam. 90GHz is an
interesting transition frequency, as MUSTANG detects both the free-free
emission characteristic of the HII region created by the Trapezium stars,
normally seen at lower frequencies, and thermal dust emission from the
background OMC1 molecular cloud, normally mapped at higher frequencies. We also
present similar data from the 150GHz GISMO camera taken on the IRAM telescope.
This map has 15" resolution. By combining the MUSTANG data with 1.4, 8, and
21GHz radio data from the VLA and GBT, we derive a new estimate of the emission
measure (EM) averaged electron temperature of Te = 11376K by an original method
relating free-free emission intensities at optically thin and optically thick
frequencies. Combining ISO-LWS data with our data, we derive a new estimate of
the dust temperature and spectral emissivity index within the 80" ISO-LWS beam
toward OrionKL/BN, Td = 42K and Beta=1.3. We show that both Td and Beta
decrease when going from the HII region and excited OMC1 interface to the
denser UV shielded part of OMC1 (OrionKL/BN, Orion S). With a model consisting
of only free-free and thermal dust emission we are able to fit data taken at
frequencies from 1.5GHz to 854GHz.Comment: 18 pages, 8 figures, submitted to the Astrophysical Journa
MUSTANG: 90 GHz Science with the Green Bank Telescope
MUSTANG is a 90 GHz bolometer camera built for use as a facility instrument
on the 100 m Robert C. Byrd Green Bank radio telescope (GBT). MUSTANG has an 8
by 8 focal plane array of transition edge sensor bolometers read out using
time-domain multiplexed SQUID electronics. As a continuum instrument on a large
single dish MUSTANG has a combination of high resolution (8") and good
sensitivity to extended emission which make it very competitive for a wide
range of galactic and extragalactic science. Commissioning finished in January
2008 and some of the first science data have been collected.Comment: 9 Pages, 5 figures, Presented at the SPIE conference on astronomical
instrumentation in 200
GMRF Estimation under Topological and Spectral Constraints
International audienceWe investigate the problem of Gaussian Markov random field selection under a non-analytic constraint: the estimated models must be compatible with a fast inference algorithm, namely the Gaussian belief propagation algorithm. To address this question, we introduce the *-IPS framework, based on iterative proportional scaling, which incrementally selects candidate links in a greedy manner. Besides its intrinsic sparsity-inducing ability, this algorithm is flexible enough to incorporate various spectral constraints, like e.g. walk summability, and topological constraints, like short loops avoidance. Experimental tests on various datasets, including traffic data from San Francisco Bay Area, indicate that this approach can deliver, with reasonable computational cost, a broad range of efficient inference models, which are not accessible through penalization with traditional sparsity-inducing norms
CMB observations with the Jodrell Bank - IAC interferometer at 33 GHz
The paper presents the first results obtained with the Jodrell Bank - IAC
two-element 33 GHz interferometer. The instrument was designed to measure the
level of the Cosmic Microwave Background (CMB) fluctuations at angular scales
of 1 - 2 degrees. The observations analyzed here were taken in a strip of the
sky at Dec = +41 deg with an element separation of 16.7 lambda, which gives a
maximum sensitivity to ~1.6 deg structures on the sky. The data processing and
calibration of the instrument are described. The sensitivity achieved in each
of the two channels is 7 micro K per resolution element. A reconstruction of
the sky at Dec = +41 deg using a maximum entropy method shows the presence of
structure at a high level of significance. A likelihood analysis, assuming a
flat CMB spatial power spectrum, gives a best estimate of the level of CMB
fluctuations of Delta Tl = 43 (+13,-12) micro K for the range l = 109 +/- 19;
the main uncertainty in this result arises from sample variance. We consider
that the contamination from the Galaxy is small. These results represent a new
determination of the CMB power spectrum on angular scales where previous
results show a large scatter; our new results are in agreement with the
theoretical predictions of the standard inflationary cold dark matter models.Comment: 11 pages, 11 figures. Web site at
http://www.jb.man.ac.uk/research/cmb/ Accepted for publication in MNRA
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