The Asteroid Terrestrial-impact Last Alert System (ATLAS) carries out its primary planetary defense mission by surveying about 13,000 deg2 at least four times per night. The resulting data set is ...useful for the discovery of variable stars to a magnitude limit fainter than r ∼ 18, with amplitudes down to 0.02 mag for bright objects. Here, we present a Data Release One catalog of variable stars based on analyzing the light curves of 142 million stars that were measured at least 100 times in the first two years of ATLAS operations. Using a Lomb-Scargle periodogram and other variability metrics, we identify 4.7 million candidate variables. Through the Space Telescope Science Institute, we publicly release light curves for all of them, together with a vector of 169 classification features for each star. We do this at the level of unconfirmed candidate variables in order to provide the community with a large set of homogeneously analyzed photometry and to avoid pre-judging which types of objects others may find most interesting. We use machine learning to classify the candidates into 15 different broad categories based on light-curve morphology. About 10% (427,000 stars) pass extensive tests designed to screen out spurious variability detections: we label these as "probable" variables. Of these, 214,000 receive specific classifications as eclipsing binaries, pulsating, Mira-type, or sinusoidal variables: these are the "classified" variables. New discoveries among the probable variables number 315,000, while 141,000 of the classified variables are new, including about 10,400 pulsating variables, 2060 Mira stars, and 74,700 eclipsing binaries.
The Asteroid Terrestrial-impact Last Alert System (ATLAS) observes most of the sky every night in search of dangerous asteroids. Its data are also used to search for photometric variability, where ...sensitivity to variability is limited by photometric accuracy. Since each exposure spans 7 6 corner to corner, variations in atmospheric transparency in excess of 0.01 mag are common, and 0.01 mag photometry cannot be achieved by using a constant flat-field calibration image. We therefore have assembled an all-sky reference catalog of approximately one billion stars to m ∼ 19 from a variety of sources to calibrate each exposure's astrometry and photometry. Gaia DR2 is the source of astrometry for this ATLAS Refcat2. The sources of g, r, i, and z photometry include Pan-STARRS DR1, the ATLAS Pathfinder photometry project, ATLAS reflattened APASS data, SkyMapper DR1, APASS DR9, the Tycho-2 catalog, and the Yale Bright Star Catalog. We have attempted to make this catalog at least 99% complete to m < 19, including the brightest stars in the sky. We believe that the systematic errors are no larger than 5 mmag rms, although errors are as large as 20 mmag in small patches near the Galactic plane.
The Covid-19 pandemic led to threatening shortages in healthcare of medical products such as face masks. Due to this major impact on our healthcare society an initiative was conducted between March ...and July 2020 for reprocessing of face masks from 19 different hospitals. This exceptional opportunity was used to study the costs impact and the carbon footprint of reprocessed face masks relative to new disposable face masks. The aim of this study is to conduct a Life Cycle Assessment (LCA) to assess and compare the climate change impact of disposed versus reprocessed face masks. In total 18.166 high quality medical FFP2 face masks were reprocessed through steam sterilization between March and July 2020. Greenhouse gas emissions during production, transport, sterilization and end-of-life processes were assessed. The background life cycle inventory data were retrieved from the ecoinvent database. The life cycle impact assessment method ReCiPe was used to translate emissions into climate change impact. The cost analysis is based on actual sterilization as well as associated costs compared to the prices of new disposable face masks. A Monte Carlo sampling was used to propagate the uncertainty of different inputs to the LCA results. The carbon footprint appears to be 58% lower for face masks which were reused for five times compared to new face masks which were used for one time only. The sensitivity analysis indicated that the loading capacity of the autoclave and rejection rate of face masks has a large influence on the carbon footprint. The estimated cost price of a reprocessed mask was €1.40 against €1.55. The Life Cycle Assessment demonstrates that reprocessed FFP2 face masks from a circular economy perspective have a lower climate change impact on the carbon footprint than new face masks. For policymakers it is important to realize that the carbon footprint of medical products such as face masks may be reduced by means of circular economy strategies. This study demonstrated a lower climate change impact and lower costs when reprocessing and reusing disposable face masks for five times. Therefore, this study may serve as an inspiration for investigating reprocessing of other medical products that may become scarce. Finally, this study advocates that circular design engineering principles should be taken into account when designing medical devices. This will lead to more sustainable products that have a lower carbon footprint and may be manufactured at lower costs.
The Asteroid Terrestrial impact Last Alert System (ATLAS) system consists of two 0.5 m Schmidt telescopes with cameras covering 29 square degrees at plate scale of 1.86 arcsec per pixel. Working in ...tandem, the telescopes routinely survey the whole sky visible from Hawaii (above δ > − 50 ° ) every two nights, exposing four times per night, typically reaching o < 19 magnitude per exposure when the moon is illuminated and c < 19.5 magnitude per exposure in dark skies. Construction is underway of two further units to be sited in Chile and South Africa which will result in an all-sky daily cadence from 2021. Initially designed for detecting potentially hazardous near earth objects, the ATLAS data enable a range of astrophysical time domain science. To extract transients from the data stream requires a computing system to process the data, assimilate detections in time and space and associate them with known astrophysical sources. Here we describe the hardware and software infrastructure to produce a stream of clean, real, astrophysical transients in real time. This involves machine learning and boosted decision tree algorithms to identify extragalactic and Galactic transients. Typically we detect 10-15 supernova candidates per night which we immediately announce publicly. The ATLAS discoveries not only enable rapid follow-up of interesting sources but will provide complete statistical samples within the local volume of 100 Mpc. A simple comparison of the detected supernova rate within 100 Mpc, with no corrections for completeness, is already significantly higher (factor 1.5 to 2) than the current accepted rates.
ATLAS: A High-cadence All-sky Survey System Tonry, J. L.; Denneau, L.; Heinze, A. N. ...
Publications of the Astronomical Society of the Pacific,
06/2018, Letnik:
130, Številka:
988
Journal Article
Recenzirano
Odprti dostop
Technology has advanced to the point that it is possible to image the entire sky every night and process the data in real time. The sky is hardly static: many interesting phenomena occur, including ...variable stationary objects such as stars or QSOs, transient stationary objects such as supernovae or M dwarf flares, and moving objects such as asteroids and the stars themselves. Funded by NASA, we have designed and built a sky survey system for the purpose of finding dangerous near-Earth asteroids (NEAs). This system, the "Asteroid Terrestrial-impact Last Alert System" (ATLAS), has been optimized to produce the best survey capability per unit cost, and therefore is an efficient and competitive system for finding potentially hazardous asteroids (PHAs) but also for tracking variables and finding transients. While carrying out its NASA mission, ATLAS now discovers more bright (m < 19) supernovae candidates than any ground based survey, frequently detecting very young explosions due to its 2 day cadence. ATLAS discovered the afterglow of a gamma-ray burst independent of the high energy trigger and has released a variable star catalog of 5 × 106 sources. This is the first of a series of articles describing ATLAS, devoted to the design and performance of the ATLAS system. Subsequent articles will describe in more detail the software, the survey strategy, ATLAS-derived NEA population statistics, transient detections, and the first data release of variable stars and transient light curves.
To determine whether the statistical fragility of randomized controlled trials (RCTs) in high-impact journals has improved in the last decade and to perform an umbrella review of all published data ...on the Fragility Index (FI) across medical specialties.
The FI was calculated for all eligible RCTs published from 2014–2021 in the New England Journal of Medicine, The Lancet, the Journal of the American Medical Association, the British Medical Journal, and the Annals of Internal Medicine. Trials reporting dichotomous, statistically significant, superiority results were eligible. All previously published systematic reviews on the FI were included in the umbrella review and analyzed by medical (sub) specialty.
Of 2,544 screened RCTs, 643 were eligible for the FI analysis. These had a median sample size of 625 (interquartile range IQR: 265–2,056), a median FI of 12 (IQR: 3–28), and a median Fragility Quotient of 0.015 (IQR: 0.004–0.045). This is an improvement compared with the median FI of 8 (IQR: 3–18) of RCTs published a decade earlier in the same five journals (P < 0.001). The umbrella review included 57 publications across 15 different medical specialties, with a total of between 10 and 692 RCTs for each specialty. The median FI ranged between two and four for all disciplines.
In the last decade, the median statistical robustness of RCTs published in high-impact journals has improved, yet the unchanged lower bound of the interquartile range reveals that statistical significance in 25% of trials is still dependent on three or less events. The umbrella review revealed that statistical fragility is prevalent across all medical specialties. The FI is an easy-to-understand metric that can be used to supplement reported P values and help readers look beyond merely reaching statistical significance.
We present the discovery of ASASSN-18ey (MAXI J1820+070), a new black hole low-mass X-ray binary (LMXB) discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN). A week after ASAS-SN ...discovered ASASSN-18ey as an optical transient, it was detected as an X-ray transient by MAXI/GCS. Here, we analyze ASAS-SN and Asteroid Terrestrial-impact Last Alert System pre-outburst optical light curves, finding evidence of intrinsic variability for several years prior to the outburst. While there was no long-term rise leading to the outburst, as has been seen in several other systems, the start of the outburst in the optical preceded that in the X-rays by 7.20 0.97 days. We analyze the spectroscopic evolution of ASASSN-18ey from pre-maximum to >100 days post-maximum. The spectra of ASASSN-18ey exhibit broad, asymmetric, double-peaked H emission. The Bowen blend (λ 4650 ) in the post-maximum spectra shows highly variable double-peaked profiles, likely arising from irradiation of the companion by the accretion disk, typical of low-mass X-ray binaries. The optical and X-ray luminosities of ASASSN-18ey are consistent with black hole low-mass X-ray binaries, both in outburst and quiescence.
Background
The healthcare sector is responsible for 4%–10% of global greenhouse gas emissions. Considering the broad range of care that obstetricians and gynaecologists provide, mitigation strategies ...within this specialty could result in significant reductions of the environmental footprint across the whole healthcare industry.
Objectives
The aim of this review was to identify for what services, procedures and products within obstetric and gynaecological care the environmental impact has been studied, to assess the magnitude of such impact and to identify mitigation strategies to diminish it.
Search strategy
The search strategy combined terms related to environmental impact, sustainability, climate change or carbon footprint, with the field of obstetrics and gynaecology.
Selection criteria
Articles reporting on the environmental impact of any service, procedure or product within the field of obstetrics and gynaecology were included. Included outcomes covered midpoint impact categories, CO2 emissions, waste generation and energy consumption.
Data collection and analysis
A systematic literature search was conducted in the databases of MEDLINE (Ovid), Embase (Ovid) and Scopus, and a grey literature search was performed on Google Scholar and two websites of gynaecological associations.
Main results
The scope of the investigated studies encompassed vaginal births, obstetric and gynaecological surgical procedures, menstrual products, vaginal specula and transportation to gynaecological oncologic consultations. Among the highest yielding mitigation strategies were displacing disposable with reusable materials and minimising content of surgical custom packs. The lowest yielding mitigation strategy was waste optimisation, including recycling.
Conclusions
This systematic review highlights opportunities for obstetricians and gynaecologists to decrease their environmental footprint in many ways. More high‐quality studies are needed to investigate the environmental impact of other aspects of women's and reproductive health care.
To determine the incidence of outcome switching in follow-up publications of randomized controlled trials. Outcome switching leads to bias where treatment benefits are more likely to be overestimated ...or based on chance.
Meta-research study including all follow-up publications 2014-2018 in the New England Journal of Medicine, The Lancet, the Journal of the American Medical Association, and the British Medical Journal. Two independent reviewers compared the primary outcomes of follow-up publications with the original RCT publication and the trial protocol.
Seventy-eight follow-up publications were identified. Thirty-one (40%) used different primary outcomes in the follow-up publication compared with the original RCT. In seventeen (55%) of these the outcome switch was neither pre-specified nor explained in the journal publication. The incidence of outcome switching in follow-up studies rose to 70% when preceded by outcome switching in the corresponding initial RCT (P< 0.001).
In this study, outcome switching occurred in 40% of follow-up publications of previously published RCTs. The majority is neither pre-specified nor explained.
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