43 research outputs found
Spatiotemporal mapping of malaria incidence in Sudan using routine surveillance data
Malaria is a serious threat to global health, with over [Formula: see text] of the cases reported in 2020 by the World Health Organization in African countries, including Sudan. Sudan is a low-income country with a limited healthcare system and a substantial burden of malaria. The epidemiology of malaria in Sudan is rapidly changing due to factors including the rapidly developing resistance to drugs and insecticides among the parasites and vectors, respectively; the growing population living in humanitarian settings due to political instability; and the recent emergence of Anopheles stephensi in the country. These factors contribute to changes in the distribution of the parasites species as well as malaria vectors in Sudan, and the shifting patterns of malaria epidemiology underscore the need for investment in improved situational awareness, early preparedness, and a national prevention and control strategy that is updated, evidence based, and proactive. A key component of this strategy is accurate, high-resolution endemicity maps of species-specific malaria. Here, we present a spatiotemporal Bayesian model, developed in collaboration with the Sudanese Ministry of Health, that predicts a fine-scale (1 km [Formula: see text] 1 km) clinical incidence and seasonality profiles for Plasmodium falciparum and Plasmodium vivax across the country. We use monthly malaria case counts for both species collected via routine surveillance between January 2017 and December 2019, as well as a suite of high-resolution environmental covariates to inform our predictions. These epidemiological maps provide a useful resource for strategic planning and cost-effective implementation of malaria interventions, thus informing policymakers in Sudan to achieve success in malaria control and elimination
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Variation in excess all-cause mortality by age, sex, and province during the first wave of the COVID-19 pandemic in Italy.
Although previous evidence suggests that the infection fatality rate from COVID-19 varies by age and sex, and that transmission intensity varies geographically within countries, no study has yet explored the age-sex-space distribution of excess mortality associated with the COVID pandemic. By applying the principles of small-area estimation to existing model formulations for excess mortality, this study develops a novel method for assessing excess mortality across small populations and assesses the pattern of COVID excess mortality by province, year, week, age group, and sex in Italy from March through May 2020. We estimate that 53,200 excess deaths occurred across Italy during this time period, compared to just 35,500 deaths where COVID-19 was registered as the underlying cause of death. Out of the total excess mortality burden, 97% of excess deaths occurred among adults over age 60, and 68% of excess deaths were concentrated among adults over age 80. The burden of excess mortality was unevenly distributed across the country, with just three of Italy's 107 provinces accounting for 32% of all excess mortality. This method for estimating excess mortality can be adapted to other countries where COVID-19 diagnostic capacity is still insufficient, and could be incorporated into public health rapid response systems
WALLABY Early Science – II. The NGC 7232 galaxy group
We report on neutral hydrogen (H I) observations of the NGC 7232 group with the Australian Square Kilometre Array Pathfinder (ASKAP). These observations were conducted as part of the Wide-field ASKAP L-Band Legacy All-sky Blind surveY (WALLABY) Early Science program with an array of 12 ASKAP antennas equipped with Phased Array Feeds, which were used to form 36 beams to map a field of view of 30 deg2. Analysing a subregion of the central beams, we detect 17 H I sources. Eleven of these detections are identified as galaxies and have stellar counterparts, of which five are newly resolved H I galaxy sources. The other six detections appear to be tidal debris in the form of H I clouds that are associated with the central triplet, NGC 7232/3, comprising the spiral galaxies NGC 7232, NGC 7232B, and NGC 7233. One of these H I clouds has a mass of MH I ∼ 3 × 108 M⊙ and could be the progenitor of a long-lived tidal dwarf galaxy. The remaining H I clouds are likely transient tidal knots that are possibly part of a diffuse tidal bridge between NGC 7232/3 and another group member, the lenticular galaxy IC 5181
WALLABY early science − V. ASKAP HI imaging of the Lyon Group of Galaxies 351
We present an HI study of the galaxy group LGG 351 usingWidefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY) early science data observed with the Australian Square Kilometre Array Pathfinder (ASKAP). LGG 351 resides behind the M 83 group at a velocity range (cz) of ∼3500–4800 km s−1 within the rich Hydra-Centaurus overdensity region. We detect 40 sources with the discovery of a tidally interacting galaxy pair and two new HI sources that are not presented in previous optical catalogues. 23 out of 40 sources have new redshifts derived from the new HI data. This study is the largest WALLABY sub-sample to date and also allows us to further validate the performance of ASKAP and the data reduction pipeline ASKAPSOFT. Extended HI emission is seen in six galaxies indicating interaction within the group, although no HI debris is found. We also detect HI in a known ultra-faint dwarf galaxy (dw 1328−29), which demonstrates that it is not a satellite of the M 83 group as previously thought. In conjunction with multiwavelength data, we find that our galaxies follow the atomic gas fraction and baryonic Tully–Fisher scaling relations derived from the GALEX Arecibo SDSS Survey. In addition, majority of our galaxies fall within the star formationmain sequence indicating inefficiency of gas removal processes in this loose galaxy group
A giant galaxy in the young Universe with a massive ring
In the local (redshift z~0) Universe, collisional ring galaxies make up only
~0.01% of galaxies and are formed by head-on galactic collisions that trigger
radially propagating density waves. These striking systems provide key
snapshots for dissecting galactic disks and are studied extensively in the
local Universe. However, not much is known about distant (z>0.1) collisional
rings. Here we present a detailed study of a ring galaxy at a look-back time of
10.8 Gyr (z=2.19). Compared with our Milky Way, this galaxy has a similar
stellar mass, but has a stellar half-light radius that is 1.5-2.2 times larger
and is forming stars 50 times faster. The large, diffuse stellar light outside
the star-forming ring, combined with a radial velocity on the ring and an
intruder galaxy nearby, provides evidence for this galaxy hosting a collisional
ring. If the ring is secularly evolved, the implied large bar in a giant disk
would be inconsistent with the current understanding of the earliest formation
of barred spirals. Contrary to previous predictions, this work suggests that
massive collisional rings were as rare 11 Gyr ago as they are today. Our
discovery offers a unique pathway for studying density waves in young galaxies,
as well as constraining the cosmic evolution of spiral disks and galaxy groups.Comment: Author's version for the main article (10 pages). The Supplementary
Information (22 pages) and a combined pdf are provided here
http://astronomy.swin.edu.au/~tyuan/paper Published version available online
http://dx.doi.org/10.1038/s41550-020-1102-
Sofia 2 - An automated, parallel H i source finding pipeline for the WALLABY survey
We present SoFiA 2, the fully automated 3D source finding pipeline for the
WALLABY extragalactic HI survey with the Australian SKA Pathfinder (ASKAP).
SoFiA 2 is a reimplementation of parts of the original SoFiA pipeline in the C
programming language and makes use of OpenMP for multi-threading of the most
time-critical algorithms. In addition, we have developed a parallel framework
called SoFiA-X that allows the processing of large data cubes to be split
across multiple computing nodes. As a result of these efforts, SoFiA 2 is
substantially faster and comes with a much reduced memory footprint compared to
its predecessor, thus allowing the large WALLABY data volumes of hundreds of
gigabytes of imaging data per epoch to be processed in real-time. The source
code has been made publicly available to the entire community under an
open-source licence. Performance tests using mock galaxies injected into
genuine ASKAP data suggest that in the absence of significant imaging artefacts
SoFiA 2 is capable of achieving near-100% completeness and reliability above an
integrated signal-to-noise ratio of about 5-6. We also demonstrate that SoFiA 2
generally recovers the location, integrated flux and w20 line width of galaxies
with high accuracy. Other parameters, including the peak flux density and w50
line width, are more strongly biased due to the influence of the noise on the
measurement. In addition, very faint galaxies below an integrated
signal-to-noise ratio of about 10 may get broken up into multiple components,
thus requiring a strategy to identify fragmented sources and ensure that they
do not affect the integrity of any scientific analysis based on the SoFiA 2
output.Comment: 16 pages, 10 figures, 1 table, accepted for publication in MNRA
WALLABY Pilot Survey: Hydra Cluster Galaxies UV and HI morphometrics
Galaxy morphology in atomic hydrogen (HI) and in the ultra-violet (UV) are
closely linked. This has motivated their combined use to quantify morphology
over the full H i disk for both H i and UV imaging. We apply galaxy
morphometrics: Concentration, Asymmetry, Gini, M20 and
Multimode-Intensity-Deviation statistics to the first moment-0 maps of the
WALLABY survey of galaxies in the Hydra cluster center. Taking advantage of
this new HI survey, we apply the same morphometrics over the full HI extent on
archival GALEX FUV and NUV data to explore how well HI truncated, extended
ultraviolet disk (XUV) and other morphological phenomena can be captured using
pipeline WALLABY data products. Extended HI and UV disks can be identified
relatively straightforward from their respective concentration. Combined with
WALLABY HI, even the shallowest GALEX data is sufficient to identify XUV disks.
Our second goal is to isolate galaxies undergoing ram-pressure stripping in the
H i morphometric space. We employ four different machine learning techniques, a
decision tree, a k-nearest neighbour, a support-vector machine, and a random
forest. Up to 80% precision and recall are possible with the Random Forest
giving the most robust results.Comment: 17 figures, 12 figures, 7 tables, accepted by MNRA
WALLABY Early Science - II. The NGC 7232 galaxy group
We report on neutral hydrogen (HI) observations of the NGC 7232 group with
the Australian Square Kilometre Array Pathfinder (ASKAP). These observations
were conducted as part of the Wide-field ASKAP L-Band Legacy All-sky Blind
surveY (WALLABY) Early Science program with an array of 12 ASKAP antennas
equipped with Phased Array Feeds, which were used to form 36 beams to map a
field of view of 30 square degrees. Analyzing a subregion of the central beams,
we detect 17 HI sources. Eleven of these detections are identified as galaxies
and have stellar counterparts, of which five are newly resolved HI galaxy
sources. The other six detections appear to be tidal debris in the form of HI
clouds that are associated with the central triplet, NGC 7232/3, comprising the
spiral galaxies NGC 7232, NGC7232B and NGC7233. One of these HI clouds has a
mass of M_HI ~ 3 x 10^8 M_sol and could be the progenitor of a long-lived tidal
dwarf galaxy. The remaining HI clouds are likely transient tidal knots that are
possibly part of a diffuse tidal bridge between NGC 7232/3 and another group
member, the lenticular galaxy IC 5181.Comment: 18 pages (including appendix), 9 figures, accepted for publication in
MNRA