110 research outputs found
The Local Volume HI Survey: star formation properties
We built a multi-wavelength dataset for galaxies from the Local Volume HI
Survey (LVHIS), which comprises 82 galaxies. We also select a sub-sample of ten
large galaxies for investigating properties in the galactic outskirts. The
LVHIS sample covers nearly four orders of magnitude in stellar mass and two
orders of magnitude in HI mass fraction (fHI). The radial distribution of HI
gas with respect to the stellar disc is correlated with fHI but with a large
scatter. We confirm the previously found correlations between the total HI mass
and star formation rate (SFR), and between HI surface densities and SFR surface
densities beyond R25. However, the former correlation becomes much weaker when
the average surface densities rather than total mass or rate are considered,
and the latter correlation also becomes much weaker when the effect of stellar
mass is removed or controlled. Hence the link between SFR and HI is
intrinsically weak in these regions, consistent with what was found on kpc
scales in the galactic inner regions. We find a strong correlation between the
SFR surface density and the stellar mass surface density, which is consistent
with the star formation models where the gas is in quasi-equilibrium with the
mid-plane pressure. We find no evidence for HI warps to be linked with
decreasing star forming efficiencies.Comment: 31 pages, 20 figures, 4 tables. Accepted for publication at 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
FAST-ASKAP Synergy: Quantifying Coexistent Tidal and Ram-Pressure Strippings in the NGC 4636 Group
Combining new HI data from a synergetic survey of ASKAP WALLABY and FAST with
the ALFALFA data, we study the effect of ram-pressure and tidal interactions in
the NGC 4636 group. We develop two parameters to quantify and disentangle these
two effects on gas stripping in HI-bearing galaxies: the strength of external
forces at the optical-disk edge, and the outside-in extents of HI-disk
stripping. We find that gas stripping is widespread in this group, affecting
80% of HI-detected non-merging galaxies, and that 34% are experiencing both
types of stripping. Among the galaxies experiencing both effects, the strengths
(and extents) of ram-pressure and tidal stripping are independent of each
other. Both strengths are correlated with HI-disk shrinkage. The tidal strength
is related to a rather uniform reddening of low-mass galaxies
() when tidal stripping is the dominating effect. In
contrast, ram pressure is not clearly linked to the color-changing patterns of
galaxies in the group. Combining these two stripping extents, we estimate the
total stripping extent, and put forward an empirical model that can describe
the decrease of HI richness as galaxies fall toward the group center. The
stripping timescale we derived decreases with distance to the center, from
around to
near the center. Gas-depletion happens
since crossing for HI-rich galaxies,
but much quicker for HI-poor ones. Our results quantify in a physically
motivated way the details and processes of environmental-effects-driven galaxy
evolution, and might assist in analyzing hydrodynamic simulations in an
observational way.Comment: 44 pages, 22 figures, 5 tables, accepted for publication in ApJ.
Tables 4 and 5 are also available in machine-readable for
WALLABY Pilot Survey: HI gas kinematics of galaxy pairs in cluster environment
We examine the H I gas kinematics of galaxy pairs in two clusters and a group using Australian Square Kilometre Array Pathfinder (ASKAP) WALLABY pilot survey observations. We compare the H I properties of galaxy pair candidates in the Hydra I and Norma clusters, and the NGC 4636 group, with those of non-paired control galaxies selected in the same fields. We perform H I profile decomposition of the sample galaxies using a tool, BAYGAUD which allows us to de-blend a line-of-sight velocity profile with an optimal number of Gaussian components. We construct H I super-profiles of the sample galaxies via stacking of their line profiles after aligning the central velocities. We fit a double Gaussian model to the super-profiles and classify them as kinematically narrow and broad components with respect to their velocity dispersions. Additionally, we investigate the gravitational instability of H I gas disks of the sample galaxies using Toomre Q parameters and H I morphological disturbances. We investigate the effect of the cluster environment on the H I properties of galaxy pairs by dividing the cluster environment into three subcluster regions (i.e., outskirts, infalling and central regions). We find that the denser cluster environment (i.e., infalling and central regions) is likely to impact the H I gas properties of galaxies in a way of decreasing the amplitude of the kinematically narrow H I gas (MnarrowHI role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; vertical-align: baseline; display: inline; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; position: relative; \u3eMHInarrowMnarrowHI/MtotalHI role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; vertical-align: baseline; display: inline; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; position: relative; \u3eMHItotalMtotalHI), and increasing the Toomre Q values of the infalling and central galaxies. This tendency is likely to be more enhanced for galaxy pairs in the cluster environment
WALLABY Pre-Pilot and Pilot Survey: the Tully Fisher Relation in Eridanus, Hydra, Norma and NGC4636 fields
The WALLABY pilot survey has been conducted using the Australian SKA Pathfinder (ASKAP). The integrated 21-cm HI line spectra are formed in a very different manner compared to usual single-dish spectra Tully-Fisher measurements. It is thus extremely important to ensure that slight differences (e.g. biases due to missing flux) are quantified and understood in order to maximise the use of the large amount of data becoming available soon. This article is based on four fields for which the data are scientifically interesting by themselves. The pilot data discussed here consist of 614 galaxy spectra at a rest wavelength of 21cm. Of these spectra, 472 are of high enough quality to be used to potentially derive distances using the Tully-Fisher relation. We further restrict the sample to the 251 galaxies whose inclination is sufficiently close to edge-on. For these, we derive Tully-Fisher distances using the deprojected WALLABY velocity widths combined with infrared (WISE W1) magnitudes. The resulting Tully-Fisher distances for the Eridanus, Hydra, Norma and NGC 4636 clusters are 21.5, 53.5, 69.4 and 23.0 Mpc respectively, with uncertainties of 5–10%, which are better or equivalent to the ones obtained in studies using data obtained with giant single dish telescopes. The pilot survey data show the benefits of WALLABY over previous giant single-dish telescope surveys. WALLABY is expected to detect around half a million galaxies with a mean redshift of 푧 = 0.05(200푀 푝푐). This study suggests that about 200,000 Tully-Fisher distances might result from the survey
RET Mutational Spectrum in Hirschsprung Disease: Evaluation of 601 Chinese Patients
Rare (RVs) and common variants of the RET gene contribute to Hirschsprung disease (HSCR; congenital aganglionosis). While RET common variants are strongly associated with the commonest manifestation of the disease (males; short-segment aganglionosis; sporadic), rare coding sequence (CDS) variants are more frequently found in the lesser common and more severe forms of the disease (females; long/total colonic aganglionosis; familial)
The United States COVID-19 Forecast Hub dataset
Academic researchers, government agencies, industry groups, and individuals have produced forecasts at an unprecedented scale during the COVID-19 pandemic. To leverage these forecasts, the United States Centers for Disease Control and Prevention (CDC) partnered with an academic research lab at the University of Massachusetts Amherst to create the US COVID-19 Forecast Hub. Launched in April 2020, the Forecast Hub is a dataset with point and probabilistic forecasts of incident cases, incident hospitalizations, incident deaths, and cumulative deaths due to COVID-19 at county, state, and national, levels in the United States. Included forecasts represent a variety of modeling approaches, data sources, and assumptions regarding the spread of COVID-19. The goal of this dataset is to establish a standardized and comparable set of short-term forecasts from modeling teams. These data can be used to develop ensemble models, communicate forecasts to the public, create visualizations, compare models, and inform policies regarding COVID-19 mitigation. These open-source data are available via download from GitHub, through an online API, and through R packages
Global, regional, and national incidence and mortality for HIV, tuberculosis, and malaria during 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013
BACKGROUND: The Millennium Declaration in 2000 brought special global attention to HIV, tuberculosis, and malaria through the formulation of Millennium Development Goal (MDG) 6. The Global Burden of Disease 2013 study provides a consistent and comprehensive approach to disease estimation for between 1990 and 2013, and an opportunity to assess whether accelerated progress has occured since the Millennium Declaration. METHODS: To estimate incidence and mortality for HIV, we used the UNAIDS Spectrum model appropriately modified based on a systematic review of available studies of mortality with and without antiretroviral therapy (ART). For concentrated epidemics, we calibrated Spectrum models to fit vital registration data corrected for misclassification of HIV deaths. In generalised epidemics, we minimised a loss function to select epidemic curves most consistent with prevalence data and demographic data for all-cause mortality. We analysed counterfactual scenarios for HIV to assess years of life saved through prevention of mother-to-child transmission (PMTCT) and ART. For tuberculosis, we analysed vital registration and verbal autopsy data to estimate mortality using cause of death ensemble modelling. We analysed data for corrected case-notifications, expert opinions on the case-detection rate, prevalence surveys, and estimated cause-specific mortality using Bayesian meta-regression to generate consistent trends in all parameters. We analysed malaria mortality and incidence using an updated cause of death database, a systematic analysis of verbal autopsy validation studies for malaria, and recent studies (2010-13) of incidence, drug resistance, and coverage of insecticide-treated bednets. FINDINGS: Globally in 2013, there were 1·8 million new HIV infections (95% uncertainty interval 1·7 million to 2·1 million), 29·2 million prevalent HIV cases (28·1 to 31·7), and 1·3 million HIV deaths (1·3 to 1·5). At the peak of the epidemic in 2005, HIV caused 1·7 million deaths (1·6 million to 1·9 million). Concentrated epidemics in Latin America and eastern Europe are substantially smaller than previously estimated. Through interventions including PMTCT and ART, 19·1 million life-years (16·6 million to 21·5 million) have been saved, 70·3% (65·4 to 76·1) in developing countries. From 2000 to 2011, the ratio of development assistance for health for HIV to years of life saved through intervention was US$4498 in developing countries. Including in HIV-positive individuals, all-form tuberculosis incidence was 7·5 million (7·4 million to 7·7 million), prevalence was 11·9 million (11·6 million to 12·2 million), and number of deaths was 1·4 million (1·3 million to 1·5 million) in 2013. In the same year and in only individuals who were HIV-negative, all-form tuberculosis incidence was 7·1 million (6·9 million to 7·3 million), prevalence was 11·2 million (10·8 million to 11·6 million), and number of deaths was 1·3 million (1·2 million to 1·4 million). Annualised rates of change (ARC) for incidence, prevalence, and death became negative after 2000. Tuberculosis in HIV-negative individuals disproportionately occurs in men and boys (versus women and girls); 64·0% of cases (63·6 to 64·3) and 64·7% of deaths (60·8 to 70·3). Globally, malaria cases and deaths grew rapidly from 1990 reaching a peak of 232 million cases (143 million to 387 million) in 2003 and 1·2 million deaths (1·1 million to 1·4 million) in 2004. Since 2004, child deaths from malaria in sub-Saharan Africa have decreased by 31·5% (15·7 to 44·1). Outside of Africa, malaria mortality has been steadily decreasing since 1990. INTERPRETATION: Our estimates of the number of people living with HIV are 18·7% smaller than UNAIDS's estimates in 2012. The number of people living with malaria is larger than estimated by WHO. The number of people living with HIV, tuberculosis, or malaria have all decreased since 2000. At the global level, upward trends for malaria and HIV deaths have been reversed and declines in tuberculosis deaths have accelerated. 101 countries (74 of which are developing) still have increasing HIV incidence. Substantial progress since the Millennium Declaration is an encouraging sign of the effect of global action. FUNDING: Bill & Melinda Gates Foundation
Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial
Background: Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes. Methods: We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18–85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR)25–75 mL/min per 1·73 m 2 of body surface area, and a urine albumin-to-creatinine ratio (UACR)of 300–5000 mg/g who had received maximum labelled or tolerated renin–angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders)were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days)or end-stage kidney disease (eGFR <15 mL/min per 1·73 m 2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure)in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532. Findings: Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325)or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4–2·9). 79 (6·0%)of 1325 patients in the atrasentan group and 105 (7·9%)of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR]0·65 [95% CI 0·49–0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%)of 1325 patients in the atrasentan group and 34 (2·6%)of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85–2·07]; p=0·208). 58 (4·4%)patients in the atrasentan group and 52 (3·9%)in the placebo group died (HR 1·09 [95% CI 0·75–1·59]; p=0·65). Interpretation: Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. Funding: AbbVie
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