171 research outputs found
Discovery of an old nova remnant in the Galactic globular cluster M 22
A nova is a cataclysmic event on the surface of a white dwarf in a binary
system that increases the overall brightness by several orders of magnitude.
Although binary systems with a white dwarf are expected to be overabundant in
globular clusters (GCs) compared to the Galaxy, only two novae from Galactic
globular clusters have been observed. We present the discovery of an emission
nebula in the Galactic globular cluster M 22 (NGC 6656) in observations made
with the integral-field spectrograph MUSE. We extract the spectrum of the
nebula and use the radial velocity determined from the emission lines to
confirm that the nebula is part of NGC 6656. Emission-line ratios are used to
determine the electron temperature and density. It is estimated to have a mass
of 1 to solar masses. This mass and the emission-line
ratios indicate that the nebula is a nova remnant. Its position coincides with
the reported location of a 'guest star', an ancient Chinese term for
transients, observed in May 48 BCE. With this discovery, this nova may be one
of the oldest confirmed extrasolar events recorded in human history.Comment: 7 pages, 3 figures; accepted for publication in Astronomy &
Astrophysic
A MUSE map of the central Orion Nebula (M 42)
We present a new integral-field spectroscopic dataset of the central part of
the Orion Nebula (M 42), observed with the MUSE instrument at the ESO VLT. We
reduced the data with the public MUSE pipeline. The output products are two
FITS cubes with a spatial size of ~5.9'x4.9' (corresponding to ~0.76 pc x 0.63
pc) and a contiguous wavelength coverage of 4595...9366 Angstrom, spatially
sampled at 0.2". We provide two versions with a sampling of 1.25 Angstrom and
0.85 Angstrom in dispersion direction. Together with variance cubes these files
have a size of 75 and 110 GiB on disk. They represent one of the largest
integral field mosaics to date in terms of information content. We make them
available for use in the community. To validate this dataset, we compare world
coordinates, reconstructed magnitudes, velocities, and absolute and relative
emission line fluxes to the literature and find excellent agreement. We derive
a two-dimensional map of extinction and present de-reddened flux maps of
several individual emission lines and of diagnostic line ratios. We estimate
physical properties of the Orion Nebula, using the emission line ratios [N II]
and [S III] (for the electron temperature ) and [S II] and [Cl III] (for
the electron density ), and show two-dimensional images of the velocity
measured from several bright emission lines.Comment: Resubmitted to A&A after incorporating referee comments; access to
full dataset via http://muse-vlt.eu/science/data-release
Inferring Risks of Coronavirus Transmission from Community Household Data
The response of many governments to the COVID-19 pandemic has involved
measures to control within- and between-household transmission, providing
motivation to improve understanding of the absolute and relative risks in these
contexts. Here, we perform exploratory, residual-based, and
transmission-dynamic household analysis of the Office for National Statistics
(ONS) COVID-19 Infection Survey (CIS) data from 26 April 2020 to 15 July 2021
in England. This provides evidence for: (i) temporally varying rates of
introduction of infection into households broadly following the trajectory of
the overall epidemic and vaccination programme; (ii) Susceptible-Infectious
Transmission Probabilities (SITPs) of within-household transmission in the
15-35% range; (iii) the emergence of the Alpha and Delta variants, with the
former being around 50% more infectious than wildtype and 35% less infectious
than Delta within households; (iv) significantly (in the range 25-300%) more
risk of bringing infection into the household for workers in patient-facing
roles pre-vaccine; (v) increased risk for secondary school-age children of
bringing the infection into the household when schools are open; (vi) increased
risk for primary school-age children of bringing the infection into the
household when schools were open since the emergence of new variants.Comment: 27 pages, 7 figure
Evaluating the impact of a very low-cost intervention to increase practicesâ engagement with data and change prescribing behaviour: a randomized trial in English primary care
Background
Unsolicited feedback can solicit changes in prescribing.
Objectives
Determine whether a low-cost intervention increases cliniciansâ engagement with data, and changes prescribing; with or without behavioural science techniques.
Methods
Randomized trial (ISRCTN86418238). The highest prescribing practices in England for broad-spectrum antibiotics were allocated to: feedback with behavioural impact optimization; plain feedback; or no intervention. Feedback was sent monthly for 3 months by letter, fax and email. Each included a link to a prescribing dashboard. The primary outcomes were dashboard usage and change in prescribing.
Results
A total of 1401 practices were randomized: 356 behavioural optimization, 347 plain feedback, and 698 control. For the primary engagement outcome, more intervention practices had their dashboards viewed compared with controls [65.7% versus 55.9%; RD 9.8%, 95% confidence intervals (CIs): 4.76% to 14.9%, P < 0.001]. More plain feedback practices had their dashboard viewed than behavioural feedback practices (69.1% versus 62.4%); but not meeting the P < 0.05 threshold (6.8%, 95% CI: â0.19% to 13.8%, P = 0.069). For the primary prescribing outcome, intervention practices possibly reduced broad-spectrum prescribing to a greater extent than controls (1.42% versus 1.12%); but again not meeting the P < 0.05 threshold (coefficient â0.31%, CI: â0.7% to 0.1%, P = 0.104). The behavioural impact group reduced broad-spectrum prescribing to a greater extent than plain feedback practices (1.63% versus 1.20%; coefficient 0.41%, CI: 0.007% to 0.8%, P = 0.046). No harms were detected.
Conclusions
Unsolicited feedback increased practicesâ engagement with data, with possible slightly reduced antibiotic prescribing (P = 0.104). Behavioural science techniques gave greater prescribing effects. The modest effects on prescribing may reflect saturation from similar initiatives on antibiotic prescribing.
Clinical Trial Registration
ISRCTN86418238
Unveiling the counter-rotating nature of the kinematically distinct core in NGC5813 with MUSE
Multi-Unit Spectroscopic Explorer (MUSE) observations of NGC5813 reveal a complex structure in the velocity dispersion map, previously hinted at by SAURON observations. The structure is reminiscent of velocity dispersion maps of galaxies comprising two counter-rotating discs, and might explain the existence of the kinematically distinct core (KDC). Further evidence for two counter-rotating components comes from the analysis of the higher moments of the stellar line-of-sight velocity distributions and fitting MUSE spectra with two separate Gaussian line-of-sight velocity distributions. The emission-line kinematics show evidence of being linked to the present cooling flows and the buoyant cavities seen in X-rays. We detect ionized gas in a nuclear disc-like structure, oriented like the KDC, which is, however, not directly related to the KDC. We build an axisymmetric Schwarzschild dynamical model, which shows that the MUSE kinematics can be reproduced well with two counter-rotating orbit families, characterized by relatively low angular momentum components, but clearly separated in integral phase space and with radially varying contributions. The model indicates that the counter-rotating components in NGC5813 are not thin discs, but dynamically hot structures. Our findings give further evidence that KDCs in massive galaxies should not necessarily be considered as structurally or dynamically decoupled regions, but as the outcomes of the mixing of different orbital families, where the balance in the distribution of mass of the orbital families is crucial. We discuss the formation of the KDC in NGC5813 within the framework of gas accretion, binary mergers and formation of turbulent thick discs from cold streams at high redshif
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The botanical education extinction and the fall of plant awareness
Civilization is dependent upon plants for survival. Plants permeate our every moment and our relationship with them will dictate how we will manage the threats of climate change and ecological collapse defining the Anthropocene. Yet, despite the significance of plants and the critical role they have played in shaping ecosystems, civilizations, and human cultures, many people are now disconnected from the botanical world. Students are presented with little plant content, particularly identification, compared with animal content. Consequently, we are producing few plant scientists and educating fewer scientists about plants. This drives a self-accelerating cycle we term . A process of knowledge erosion, that in this instance contributes to our separation from the natural world, makes us blind to the biodiversity crisis and inhibits our ability to restore it. We argue that neglecting the importance of plants within education threatens the foundations of industries and professions that rely on this knowledge. Furthermore, this extinction of botanical education creates an existential threat: Without the skills to fully comprehend the scale of and solutions to human-induced global change, how do we as a society combat it? We present key research agendas that will enable us to reverse the extinction of botanical education and highlight the critical role plants play on the global stage
Optically-passive spirals: The missing link in gradual star formation suppression upon cluster infall
Galaxies migrate from the blue cloud to the red sequence when their star
formation is quenched. Here, we report on galaxies quenched by environmental
effects and not by mergers or strong AGN as often invoked: They form stars at a
reduced rate which is optically even less conspicuous, and manifest a
transition population of blue spirals evolving into S0 galaxies. These
'optically passive' or 'red spirals' are found in large numbers in the STAGES
project (and by Galaxy Zoo) in the infall region of clusters and groups.Comment: Proceedings of "The Starburst-AGN connection" conference held in
Shanghai, Oct 27-31, 200
Obscured star formation in intermediate-density environments:A Spitzer study of the Abell 901/902 supercluster
We explore the amount of obscured star formation as a function of environment in the Abell 901/902 (A901/902) supercluster at z = 0.165 in conjunction with a field sample drawn from the A901 and CDFS fields, imaged with the Hubble Space Telescope as part of the Space Telescope A901/902 Galaxy Evolution Survey and Galaxy Evolution from Morphology and Spectral Energy Distributions (SEDs) Survey. We combine the combo-17 near-UV/optical SED with Spitzer 24 mu m photometry to estimate both the unobscured and obscured star formation in galaxies with M-* > 10(10) M-circle dot. We find that the star formation activity in massive galaxies is suppressed in dense environments, in agreement with previous studies. Yet, nearly 40% of the star-forming (SF) galaxies have red optical colors at intermediate and high densities. These red systems are not starbursting; they have star formation rates (SFRs) per unit stellar mass similar to or lower than blue SF galaxies. More than half of the red SF galaxies have low infrared-to-ultraviolet (IR-to-UV) luminosity ratios, relatively high Sersicindices, and they are equally abundant at all densities. They might be gradually quenching their star formation, possibly but not necessarily under the influence of gas-removing environmental processes. The other greater than or similar to 40% of the red SF galaxies have high IR-to-UV luminosity ratios, indicative of high dust obscuration. They have relatively high specific SFRs and are more abundant at intermediate densities. Our results indicate that while there is an overall suppression in the SF galaxy fraction with density, the small amount of star formation surviving the cluster environment is to a large extent obscured, suggesting that environmental interactions trigger a phase of obscured star formation, before complete quenching
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