1,082 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
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
The GUCY2C Tumor Suppressor is the Nexus of a Paracrine Hormone Axis Preventing Radiotherapy-Induced Gastrointestinal (GI) Toxicity
Purpose/Objective: Radiation-induced GI toxicity is the primary dose limitation compromising therapy in cancer patients treated with radiation therapy. GUCY2C is the intestinal receptor for diarrheagenic bacterial enterotoxins and the endogenous paracrine hormones guanylin and uroguanylin. Following genomic insult, cyclic (c)GMP produced by ligand activation of GUCY2C enhances DNA damage sensing and repair in intestinal cells. Here, we show that the GUCY2C-cGMP axis mediates p53-dependent radioprotection of intestinal epithelial cells.
American Society for Therapeutic Radiation Oncology (ASTRO) 52nd Annual Meeting October 31 - November 4, San Diego, C
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
Implications of a High Angular Resolution Image of the Sunyaev-Zel'dovich Effect in RXJ1347-1145
The most X-ray luminous cluster known, RXJ1347-1145 (z=0.45), has been the
object of extensive study across the electromagnetic spectrum. We have imaged
the Sunyaev-Zel'dovich Effect (SZE) at 90 GHz (3.3 mm) in RXJ1347-1145 at 10"
resolution with the 64-pixel MUSTANG bolometer array on the Green Bank
Telescope (GBT), confirming a previously reported strong, localized enhancement
of the SZE 20" to the South-East of the center of X-ray emission. This
enhancement of the SZE has been interpreted as shock-heated (> 20 keV) gas
caused by an ongoing major (low mass-ratio) merger event. Our data support this
interpretation. We also detect a pronounced asymmetry in the projected cluster
pressure profile, with the pressure just east of the cluster core ~1.6 times
higher than just to the west. This is the highest resolution image of the SZE
made to date.Comment: 9 pages, 7 figures; accepted for publication in 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
Measuring and Correcting Wind-Induced Pointing Errors of the Green Bank Telescope Using an Optical Quadrant Detector
Wind-induced pointing errors are a serious concern for large-aperture
high-frequency radio telescopes. In this paper, we describe the implementation
of an optical quadrant detector instrument that can detect and provide a
correction signal for wind-induced pointing errors on the 100m diameter Green
Bank Telescope (GBT). The instrument was calibrated using a combination of
astronomical measurements and metrology. We find that the main wind-induced
pointing errors on time scales of minutes are caused by the feedarm being blown
along the direction of the wind vector. We also find that wind-induced
structural excitation is virtually non-existent. We have implemented offline
software to apply pointing corrections to the data from imaging instruments
such as the MUSTANG 3.3 mm bolometer array, which can recover ~70% of
sensitivity lost due to wind-induced pointing errors. We have also performed
preliminary tests that show great promise for correcting these pointing errors
in real-time using the telescope's subreflector servo system in combination
with the quadrant detector signal.Comment: 17 pages, 11 figures; accepted for publication in PAS
The Atacama Cosmology Telescope: Physical Properties of Sunyaev-Zel'dovich Effect Clusters on the Celestial Equator
We present the optical and X-ray properties of 68 galaxy clusters selected
via the Sunyaev-Zel'dovich Effect at 148 GHz by the Atacama Cosmology Telescope
(ACT). Our sample, from an area of 504 square degrees centered on the celestial
equator, is divided into two regions. The main region uses 270 square degrees
of the ACT survey that overlaps with the co-added ugriz imaging from the Sloan
Digital Sky Survey (SDSS) over Stripe 82 plus additional near-infrared pointed
observations with the Apache Point Observatory 3.5-meter telescope. We confirm
a total of 49 clusters to z~1.3, of which 22 (all at z>0.55) are new
discoveries. For the second region the regular-depth SDSS imaging allows us to
confirm 19 more clusters up to z~0.7, of which 10 systems are new. We present
the optical richness, photometric redshifts, and separation between the SZ
position and the brightest cluster galaxy (BCG). We find no significant offset
between the cluster SZ centroid and BCG location and a weak correlation between
optical richness and SZ-derived mass. We also present X-ray fluxes and
luminosities from the ROSAT All Sky Survey which confirm that this is a massive
sample. One of the newly discovered clusters, ACT-CL J0044.4+0113 at z=1.1
(photometric), has an integrated XMM-Newton X-ray temperature of kT_x=7.9+/-1.0
keV and combined mass of M_200a=8.2(-2.5,+3.3)x10^14 M_sun/h70 placing it among
the most massive and X-ray-hot clusters known at redshifts beyond z=1. We also
highlight the optically-rich cluster ACT-CL J2327.4-0204 (RCS2 2327) at z=0.705
(spectroscopic) as the most significant detection of the whole equatorial
sample with a Chandra-derived mass of M_200a=1.9(-0.4,+0.6)x10^15 M_sun/h70,
comparable to some of the most massive known clusters like "El Gordo" and the
Bullet Cluster.Comment: 18 pages, 12 figures. Accepted to the Astrophysical Journal. New
version includes minor changes in the accepted pape
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