We have conducted a Galactic plane survey of methanol masers at 6668 MHz using a seven-beam receiver on the Parkes telescope. Here we present results from the first part, which provides sensitive ...unbiased coverage of a large region around the Galactic Centre. Details are given for 183 methanol maser sites in the longitude range 345° through the Galactic Centre to 6°. Within 6° of the Galactic Centre, we found 88 maser sites, of which more than half (48) are new discoveries. The masers are confined to a narrow Galactic latitude range, indicative of many sources at the Galactic Centre distance and beyond, and confined to a thin disc population; there is no high-latitude population that might be ascribed to the Galactic bulge. Within 2° of the Galactic Centre the maser velocities all lie between −60 and +77 km s−1, a range much smaller than the 540 km s−1 range observed in CO. Elsewhere, the maser with highest positive velocity (+107 km s−1) occurs, surprisingly, near longitude 355° and is probably attributable to the Galactic bar. The maser with the most negative velocity (−127 km s−1) is near longitude 346°, within the longitude–velocity locus of the near side of the ‘3-kpc arm’. It has the most extreme velocity of a clear population of masers associated with the near and far sides of the 3-kpc arm. Closer to the Galactic Centre the maser space density is generally low, except within 0.25 kpc of the Galactic Centre itself, the ‘Galactic Centre zone’, where it is 50 times higher, which is hinted at by the longitude distribution, and confirmed by the unusual velocities.
We present the fifth portion of an unbiased survey of the Galactic plane, |b| ≤ 2°, for 6668-MHz methanol masers. This section of the survey completes the Galactic longitude range visible to the ...Parkes radio telescope, incorporating the longitude range 20°–60°. Within this section of the survey we find 265 methanol masers, 64 new to the survey, bringing the total number of methanol masers detected across the full longitude coverage (186°, through 0°, to 60°) to 972 sources.
The 6-GHz multibeam maser survey – I. Techniques Green, J. A.; Caswell, J. L.; Fuller, G. A. ...
Monthly Notices of the Royal Astronomical Society,
January 2009, Letnik:
392, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A new seven-beam 6–7 GHz receiver has been built to survey the Galaxy and the Magellanic Clouds for newly forming high-mass stars that are pinpointed by strong methanol maser emission at 6668 MHz. ...The receiver was jointly constructed by Jodrell Bank Observatory (JBO) and the Australia Telescope National Facility (ATNF) and allows simultaneous coverage at 6668 and 6035 MHz. It was successfully commissioned at Parkes in 2006 January and is now being used to conduct the Parkes–Jodrell multibeam maser survey of the Milky Way. This will be the first systematic survey of the entire Galactic plane for masers of not only 6668-MHz methanol, but also 6035-MHz excited-state hydroxyl. The survey is two orders of magnitude faster than most previous systematic surveys and has an rms noise level of ∼0.17 Jy. This paper describes the observational strategy, techniques and reduction procedures of the Galactic and Magellanic Cloud surveys, together with deeper, pointed, follow-up observations and complementary observations with other instruments. It also includes an estimate of the survey detection efficiency. The 111 d of observations with the Parkes telescope have so far yielded >800 methanol sources, of which ∼350 are new discoveries. The whole project will provide the first comprehensive Galaxy-wide catalogue of 6668-MHz and 6035-MHz masers.
Complex stellar winds from evolved stars
Stars less than eight times the mass of the Sun end their lives as planetary nebulae, structures of ionized gas thrown off by the star and heated by the ...exposed stellar core. Planetary nebulae are often bipolar in shape or contain complex morphological features such as rings or spirals. Decin
et al.
observed the stellar winds of 14 stars during their asymptotic giant branch (AGB) phase of stellar evolution, which immediately precedes the planetary nebula phase. They found morphologies in the AGB winds similar to planetary nebulae and demonstrated that they are produced by the influence of a binary companion on the AGB wind.
Science
, this issue p.
1497
Complex morphologies in the winds of asymptotic giant branch stars and planetary nebulae are produced by binary interactions.
Binary interactions dominate the evolution of massive stars, but their role is less clear for low- and intermediate-mass stars. The evolution of a spherical wind from an asymptotic giant branch (AGB) star into a nonspherical planetary nebula (PN) could be due to binary interactions. We observed a sample of AGB stars with the Atacama Large Millimeter/submillimeter Array (ALMA) and found that their winds exhibit distinct nonspherical geometries with morphological similarities to planetary nebulae (PNe). We infer that the same physics shapes both AGB winds and PNe; additionally, the morphology and AGB mass-loss rate are correlated. These characteristics can be explained by binary interaction. We propose an evolutionary scenario for AGB morphologies that is consistent with observed phenomena in AGB stars and PNe.
We present the results of models that were designed to study all possible water maser transitions in the frequency range 0–1.91 THz, with particular emphasis on maser transitions that may be ...generated in evolved-star envelopes and observed with the ALMA and SOFIA telescopes. We used tens of thousands of radiative transfer models of both spin-species of H2O, spanning a considerable parameter space in number density, kinetic temperature and dust temperature. Results, in the form of maser optical depths, have been summarized in a master table. Maser transitions identified in these models were grouped according to loci of inverted regions in the density/kinetic temperature plane, a property clearly related to the dominant mode of pumping. A more detailed study of the effect of dust temperature on maser optical depth enabled us to divide the maser transitions into three groups: those with both collisional and radiative pumping schemes (22, 96, 209, 321, 325, 395, 941 and 1486 GHz), a much larger set that are predominantly radiatively pumped, and another large group with a predominantly collisional pump. The effect of accelerative and decelerative velocity shifts of up to 5 km s−1 was found to be generally modest, with the primary effect of reducing computed maser optical depths. More subtle asymmetric effects, dependent on line overlap, include maximum gains offset from zero shift by >1 km s−1, but these effects were predominantly found under conditions of weak amplification. These models will allow astronomers to use multitransition water maser observations to constrain physical conditions down to the size of individual masing clouds (size of a few astronomical units).
Aims/hypothesis
The study aimed to examine the associations between objectively measured sedentary time, breaks in sedentary time, moderate-to-vigorous physical activity (MVPA) and total physical ...activity with markers of cardiometabolic health in a population with known risk factors for type 2 diabetes mellitus.
Methods
This study reports data from two ongoing diabetes prevention programmes. Participants with known risk factors were recruited from primary care practices located within the East Midlands, UK, over the period 2010–2011. ActiGraph GT3X accelerometers (15 s epochs) were used to assess sedentary time (<25 counts per 15 s), MVPA (≥488 counts per 15 s) and total physical activity (total counts). A break was considered as any interruption in sedentary time (≥25 counts per 15 s). Linear regression examined the independent association of sedentary time, breaks in sedentary time, MVPA and total physical activity with markers of cardiometabolic health.
Results
The sample comprised 878 participants; 153 from Project STAND (Sedentary Time And Diabetes) (age 32.9 ± 5.6 years, 28.8% male) and 725 from Walking Away from Diabetes (age 63.7 ± 7.8 years, 64.8% male). Following adjustment for various covariates, including MVPA and BMI, there were detrimental linear associations of sedentary time with 2 h plasma glucose (standardised beta coefficient) (β = 0.220,
p
< 0.001), triacylglycerol (β = 0.206,
p
= 0.001) and HDL-cholesterol (β = −0.123,
p
= 0.029). Breaks in sedentary time, total physical activity and MVPA were significantly inversely associated with measures of adiposity, but not with any other cardiometabolic variables after adjustment for sedentary time and BMI.
Conclusions/interpretation
In adults at high risk of type 2 diabetes mellitus, time spent sedentary is strongly and adversely associated with cardiometabolic health and may be a more important indicator of poor health than MVPA.
Aims/hypothesis
The aim of this project was to build a new version of the United Kingdom Prospective Diabetes Study (UKPDS) Outcomes Model (UKPDS-OM1), a patient-level simulation tool for predicting ...lifetime health outcomes of people with type 2 diabetes mellitus.
Methods
Data from 5,102 UKPDS patients from the 20 year trial and the 4,031 survivors entering the 10 year post-trial monitoring period were used to derive parametric proportional hazards models predicting absolute risk of diabetes complications and death. We re-estimated the seven original event equations and estimated new equations for diabetic ulcer and some second events. The additional data permitted inclusion of new risk factor predictors such as estimated GFR. We also developed four new equations for all-cause mortality. Internal validation of model predictions of cumulative incidence of all events and death was carried out and a contemporary patient-level dataset was used to compare 10 year predictions from the original and the new models.
Results
Model equations were based on a median 17.6 years of follow-up and up to 89,760 patient-years of data, providing double the number of events, greater precision and a larger number of significant covariates. The new model, UKPDS-OM2, is internally valid over 25 years and predicts event rates for complications, which are lower than those from the existing model.
Conclusions/interpretation
The new UKPDS-OM2 has significant advantages over the existing model, as it captures more outcomes, is based on longer follow-up data, and more comprehensively captures the progression of diabetes. Its use will permit detailed and reliable lifetime simulations of key health outcomes in people with type 2 diabetes mellitus.
Plant phenology regulates ecosystem services at local and global scales and is a sensitive indicator of global change. Estimates of phenophase transition dates, such as the start of spring or end of ...fall, can be derived from sensor-based time series, but must be interpreted in terms of biologically relevant events. We use the PhenoCam archive of digital repeat photography to implement a consistent protocol for visual assessment of canopy phenology at 13 temperate deciduous forest sites throughout eastern North America, and to perform digital image analysis for time-series-based estimation of phenophase transition dates. We then compare these results to remote sensing metrics of phenophase transition dates derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Very High Resolution Radiometer (AVHRR) sensors. We present a new type of curve fit that uses a generalized sigmoid function to estimate phenology dates, and we quantify the statistical uncertainty of phenophase transition dates estimated using this method. Results show that the generalized sigmoid provides estimates of dates with less statistical uncertainty than other curve-fitting methods. Additionally, we find that dates derived from analysis of high-frequency PhenoCam imagery have smaller uncertainties than satellite remote sensing metrics of phenology, and that dates derived from the remotely sensed enhanced vegetation index (EVI) have smaller uncertainty than those derived from the normalized difference vegetation index (NDVI). Near-surface time-series estimates for the start of spring are found to closely match estimates derived from visual assessment of leaf-out, as well as satellite remote-sensing-derived estimates of the start of spring. However late spring and fall phenology metrics exhibit larger differences between near-surface and remote scales. Differences in late spring phenology between near-surface and remote scales are found to correlate with a landscape metric of deciduous forest cover. These results quantify the effect of landscape heterogeneity when aggregating to the coarser spatial scales of remote sensing, and demonstrate the importance of accurate curve fitting and vegetation index selection when analyzing and interpreting phenology time series.
Summary Background The 2014 Zaire Ebola virus outbreak highlighted the need for a safe, effective vaccine with a rapid onset of protection. We report the safety and immunogenicity of the recombinant ...vesicular stomatitis virus-Zaire Ebola virus envelope glycoprotein vaccine (rVSV∆G-ZEBOV-GP) across a 6 log10 dose range in two sequential cohorts. Methods In this phase 1b double-blind, placebo-controlled, dose-response study we enrolled and randomly assigned healthy adults (aged 18–61 years) at eight study sites in the USA to receive a single injection of vaccine or placebo, administered by intramuscular injection. In cohort 1, participants were assigned to receive 3 × 103 , 3 × 104 , 3 × 105 , or 3 × 106 PFU doses of rVSV∆G-ZEBOV-GP or placebo. In cohort 2, participants were assigned to receive 3 × 106 , 9 × 106 , 2 × 107 , or 1 × 108 PFU doses of rVSV∆G-ZEBOV-GP or placebo. Participants were centrally allocated by the study statistician to vaccine groups or placebo through computer-generated randomisation lists. The primary safety outcome was incidence of adverse events within 14 days in the modified intention-to-treat population (all randomly assigned participants who received vaccine or placebo), and the primary outcome for immunogenicity was IgG ELISA antibody titres at day 28 in the per-protocol population. Surveillance was enhanced for arthritis and dermatitis through to day 56. This study is registered with ClinicalTrials.gov , number NCT02314923. Findings Between Dec 26, 2014, and June 8, 2015, 513 participants were enrolled and randomly assigned; one was not immunised because of unsuccessful phlebotomy. In cohort 1, 256 participants received vaccine (3 × 103 n=64, 3 × 104 n=64, 3 × 105 n=64, or 3 × 106 PFU n=64) and 74 received placebo. In cohort 2, 162 participants received vaccine (3 × 106 n=20, 9 × 106 n=47, 2 × 107 n=47, or 1 × 108 PFU n=48) and 20 received placebo. Most adverse events occurred in the first day after vaccination, and were mild to moderate in intensity, of a short duration, and more frequent at high vaccine doses (9 × 106 PFU and greater). At the 2 × 107 PFU dose (used in phase 3 trials), the most common local adverse events versus placebo within the first 14 days were arm pain (57·4% 27 of 47 vs 7·4% seven of 94) and local tenderness (59·6% 28 of 47 vs 8·5% eight of 94). The most common systemic adverse events at the 2 × 107 PFU dose versus placebo, occurring in the first 14 days, were headache (46·8% 22 of 47 vs 27·7% 26 of 94), fatigue (38·3% 18 of 47 vs 19·1% 18 of 94), myalgia (34·0% 16 of 47 vs 10·6% 10 of 94), subjective fever (29·8% 14 of 47 vs 2·1% two of 94), shivering or chills (27·7% 13 of 47 vs 7·4% seven of 94), sweats (23·4% 11 of 47 vs 3·2% three of 94), joint aches and pain (19·1% nine of 47 vs 7·4% seven of 94), objective fever (14·9% seven of 47 vs 1·1% one of 94), and joint tenderness or swelling (14·9% seven of 47 vs 2·1% two of 94). Self-limited, post-vaccination arthritis occurred in 4·5% (19 of 418) of vaccinees (median onset 12·0 days IQR 10–14; median duration 8·0 days 6–15) versus 3·2% (three of 94) of controls (median onset 15·0 days 6–20; median duration 47·0 days 37–339), with no apparent dose relationship. Post-vaccination dermatitis occurred in 5·7% (24 of 418) of vaccinees (median onset 9·0 days IQR 2–12; median duration 7·0 days 4–9) versus 3·2% (three of 94) of controls (median onset 5·0 days 3–53; median duration 33·0 days 5–370). A low-level, transient, dose-dependent viraemia occurred in concert with early reactogenicity. Antibody responses were observed in most participants by day 14. IgG and neutralising antibody titres were dose-related (p=0·0003 for IgG ELISA and p<0·0001 for the 60% plaque-reduction neutralisation test PRNT60 by linear trend). On day 28 at the 2 × 107 PFU dose, the geometric mean IgG ELISA endpoint titre was 1624 (95% CI 1146–2302) and seroconversion was 95·7% (95% CI 85·5–98·8); the geometric mean neutralising antibody titre by PRNT60 was 250 (176–355) and seroconversion was 95·7% (85·5–98·8). These robust immunological responses were sustained for 1 year. Interpretation rVSV∆G-ZEBOV-GP was well tolerated and stimulated a rapid onset of binding and neutralising antibodies, which were maintained through to day 360. The immunogenicity results support selection of the 2 × 107 PFU dose. Funding Biomedical Advanced Research and Development Authority, US Department of Health and Human Services.
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