Abstract
We introduce the Automatic Learning for the Rapid Classification of Events (ALeRCE) broker, an astronomical alert broker designed to provide a rapid and self-consistent classification of ...large etendue telescope alert streams, such as that provided by the Zwicky Transient Facility (ZTF) and, in the future, the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). ALeRCE is a Chilean-led broker run by an interdisciplinary team of astronomers and engineers working to become intermediaries between survey and follow-up facilities. ALeRCE uses a pipeline that includes the real-time ingestion, aggregation, cross-matching, machine-learning (ML) classification, and visualization of the ZTF alert stream. We use two classifiers: a stamp-based classifier, designed for rapid classification, and a light curve–based classifier, which uses the multiband flux evolution to achieve a more refined classification. We describe in detail our pipeline, data products, tools, and services, which are made public for the community (see
https://alerce.science
). Since we began operating our real-time ML classification of the ZTF alert stream in early 2019, we have grown a large community of active users around the globe. We describe our results to date, including the real-time processing of 1.5 × 10
8
alerts, the stamp classification of 3.4 × 10
7
objects, the light-curve classification of 1.1 × 10
6
objects, the report of 6162 supernova candidates, and different experiments using LSST-like alert streams. Finally, we discuss the challenges ahead in going from a single stream of alerts such as ZTF to a multistream ecosystem dominated by LSST.
Heart failure treatment guidelines emphasize daily weight monitoring for patients with heart failure, but data to support this practice are lacking. Using a technology-based heart failure monitoring ...system, we determined whether daily reporting of weight and symptoms in patients with advanced heart failure would reduce rehospitalization and mortality rates despite aggressive guideline-driven heart failure care.
This was a randomized, controlled trial. Patients hospitalized with New York Heart Association class III or IV heart failure, with a left ventricular ejection fraction ≤35% were randomized to receive heart failure program care or heart failure program care plus the AlereNet system (Alere Medical, Reno, Nev) and followed-up for 6 months. The primary end point was 6-month hospital readmission rate. Secondary end points included mortality, heart failure hospitalization readmission rate, emergency room visitation rate, and quality of life.
Two hundred eighty patients from 16 heart failure centers across the United States were randomized: 138 received the AlereNet system and 142 received standard care. Mean age was 59 ± 15 years and 68% were male. The population had very advanced heart failure, New York Heart Association class III (75%) or IV (25%), as evidenced by serum norepinepherine levels, 6-minute walk distance and outcomes. No differences in hospitalization rates were observed. There was a 56.2% reduction in mortality (
P < .003) for patients randomized to the AlereNet group.
This is the largest multicenter, randomized trial of a technology-based daily weight and symptom-monitoring system for patients with advanced heart failure. Despite no difference in the primary end point of rehospitalization rates, mortality was significantly reduced for patients randomized to the AlereNet system without an increase in utilization, despite specialized and aggressive heart failure care in both groups.
The problem of AMR remains unsolved because standardized schemes for diagnosis and treatment remains contentious. Therefore, a consensus conference was organized to discuss the current status of ...antibody-mediated rejection (AMR) in heart transplantation.
The conference included 83 participants (transplant cardiologists, surgeons, immunologists and pathologists) representing 67 heart transplant centers from North America, Europe, and Asia who all participated in smaller break-out sessions to discuss the various topics of AMR and attempt to achieve consensus.
A tentative pathology diagnosis of AMR was established, however, the pathologist felt that further discussion was needed prior to a formal recommendation for AMR diagnosis. One of the most important outcomes of this conference was that a clinical definition for AMR (cardiac dysfunction and/or circulating donor-specific antibody) was no longer believed to be required due to recent publications demonstrating that asymptomatic (no cardiac dysfunction) biopsy-proven AMR is associated with subsequent greater mortality and greater development of cardiac allograft vasculopathy. It was also noted that donor-specific antibody is not always detected during AMR episodes as the antibody may be adhered to the donor heart. Finally, recommendations were made for the timing for specific staining of endomyocardial biopsy specimens and the frequency by which circulating antibodies should be assessed. Recommendations for management and future clinical trials were also provided.
The AMR Consensus Conference brought together clinicians, pathologists and immunologists to further the understanding of AMR. Progress was made toward a pathology AMR grading scale and consensus was accomplished regarding several clinical issues.
The advent of next-generation survey instruments, such as the Vera C. Rubin Observatory and its Legacy Survey of Space and Time (LSST), is opening a window for new research in time-domain astronomy. ...The Extended LSST Astronomical Time-Series Classification Challenge (ELAsTiCC) was created to test the capacity of brokers to deal with a simulated LSST stream. We describe ATAT, the Astronomical Transformer for time series And Tabular data, a classification model conceived by the ALeRCE alert broker to classify light-curves from next-generation alert streams. ATAT was tested in production during the first round of the ELAsTiCC campaigns. ATAT consists of two Transformer models that encode light curves and features using novel time modulation and quantile feature tokenizer mechanisms, respectively. ATAT was trained on different combinations of light curves, metadata, and features calculated over the light curves. We compare ATAT against the current ALeRCE classifier, a Balanced Hierarchical Random Forest (BHRF) trained on human-engineered features derived from light curves and metadata. When trained on light curves and metadata, ATAT achieves a macro F1-score of 82.9 +- 0.4 in 20 classes, outperforming the BHRF model trained on 429 features, which achieves a macro F1-score of 79.4 +- 0.1. The use of Transformer multimodal architectures, combining light curves and tabular data, opens new possibilities for classifying alerts from a new generation of large etendue telescopes, such as the Vera C. Rubin Observatory, in real-world brokering scenarios.
PFS (the Planetary Fourier Spectrometer) covers the range 1.25 – 45 μm with spectral resolution about 2 cm
−1 and angular resolution 0.035 – 0.070 rad (10 – 20 km on the Martian surface working at ...the periapsis). The instrument has two spectral channels: shortwavelength (SW) and longwavelength (LW) with a boundary near 5 μm. The photoconductive detector (PbSe) is used in the SW channel and the pyroelectric in LW channel. The main optical units of both channels are rotating interferometers with cubic mirror corner reflectors. The infrared radiation from Mars is directed to the interferometers by the pointing system that allows to observe selected points on the Martian surface. A “dichroic” plate splits the beam between LW and SW channels. Several hundred spectra will be obtained during one periapsis passage. These spectra will be used for investigation of Martian atmosphere (temperature and pressure vertical profiles, variations of small constituents such as H
2O and CO, pressure near the surface, aerosol distribution, composition and optical depth) and some of surface properties (thermal, compositional, textural). Scientific facilities of six countries (Italy, Russia, Germany, Poland, France and Spain) cooperate in the work on this experiment.
We introduce the Automatic Learning for the Rapid Classification of Events (ALeRCE) broker, an astronomical alert broker designed to provide a rapid and self--consistent classification of large ...etendue telescope alert streams, such as that provided by the Zwicky Transient Facility (ZTF) and, in the future, the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). ALeRCE is a Chilean--led broker run by an interdisciplinary team of astronomers and engineers, working to become intermediaries between survey and follow--up facilities. ALeRCE uses a pipeline which includes the real--time ingestion, aggregation, cross--matching, machine learning (ML) classification, and visualization of the ZTF alert stream. We use two classifiers: a stamp--based classifier, designed for rapid classification, and a light--curve--based classifier, which uses the multi--band flux evolution to achieve a more refined classification. We describe in detail our pipeline, data products, tools and services, which are made public for the community (see \url{https://alerce.science}). Since we began operating our real--time ML classification of the ZTF alert stream in early 2019, we have grown a large community of active users around the globe. We describe our results to date, including the real--time processing of \(9.7\times10^7\) alerts, the stamp classification of \(1.9\times10^7\) objects, the light curve classification of \(8.5\times10^5\) objects, the report of 3088 supernova candidates, and different experiments using LSST-like alert streams. Finally, we discuss the challenges ahead to go from a single-stream of alerts such as ZTF to a multi--stream ecosystem dominated by LSST.
We present rest-frame optical spectra from the FMOS-COSMOS survey of 12 z ∼ 1.6 Herschel starburst galaxies, with star formation rate (SFR) elevated by ×8, on average, above the star-forming main ...sequence (MS). Comparing the H to IR luminosity ratio and the Balmer decrement, we find that the optically thin regions of the sources contain on average only ∼10% of the total SFR, whereas ∼90% come from an extremely obscured component that is revealed only by far-IR observations and is optically thick even in H . We measure the N ii6583/H ratio, suggesting that the less obscured regions have a metal content similar to that of the MS population at the same stellar masses and redshifts. However, our objects appear to be metal-rich outliers from the metallicity-SFR anticorrelation observed at fixed stellar mass for the MS population. The S ii6732/S ii6717 ratio from the average spectrum indicates an electron density ne ∼ 1100 cm−3 , larger than what was estimated for MS galaxies but only at the 1.5 level. Our results provide supporting evidence that high-z MS outliers are analogous of local ULIRGs and are consistent with a major-merger origin for the starburst event.
ABSTRACT
We report the serendipitous discovery of a dust-obscured galaxy observed as part of the Atacama Large Millimeter Array (ALMA) Large Program to INvestigate C ii at Early times (ALPINE). While ...this galaxy is detected both in line and continuum emissions in ALMA Band 7, it is completely dark in the observed optical/near-infrared bands and only shows a significant detection in the UltraVISTA Ks band. We discuss the nature of the observed ALMA line, that is C ii at $z$ ∼ 4.6 or high-J CO transitions at $z$ ∼ 2.2. In the first case, we find a C ii/FIR luminosity ratio of $\mathrm{log}{(L_{\mathrm{ C}\, \rm {\small {II}}}/L_{\mathrm{ FIR}})} \sim -2.5$, consistent with the average value for local star-forming galaxies (SFGs). In the second case instead, the source would lie at larger CO luminosities than those expected for local SFGs and high-z submillimetre galaxies. At both redshifts, we derive the star formation rate (SFR) from the ALMA continuum and the physical parameters of the galaxy, such as the stellar mass (M*), by fitting its spectral energy distribution. Exploiting the results of this work, we believe that our source is a ‘main-sequence’, dusty SFG at $z$ = 4.6 (i.e. C ii emitter) with $\mathrm{log(SFR/M_{\odot }\, yr^{-1})}\sim 1.4$ and log(M*/M⊙) ∼ 9.9. As a support to this scenario our galaxy, if at this redshift, lies in a massive protocluster recently discovered at $z$ ∼ 4.57, at only ∼1 proper Mpc from its centre. This work underlines the crucial role of the ALPINE survey in making a census of this class of objects, in order to unveil their contribution to the global SFR density at the end of the Reionization epoch.
ABSTRACT
We use a sample of 706 galaxies, selected as O iiλ3727 (O ii) emitters in the Survey for High-z Absorption Red and Dead Sources (SHARDS) on the CANDELS/GOODS-N field, to study the ...differential attenuation of the nebular emission with respect to the stellar continuum. The sample includes only galaxies with a counterpart in the infrared and log10(M*/M⊙) > 9, over the redshift interval 0.3 ≲ z ≲ 1.5. Our methodology consists in the comparison of the star formation rates inferred from O ii and Hα emission lines with a robust quantification of the total star-forming activity (SFR TOT) that is independently estimated based on both infrared and ultraviolet (UV) luminosities. We obtain $f\, =\, E(B-V)_{\mathrm{stellar}}$/E(B − V)nebular = 0.69$^{0.71}_{0.69}$ and 0.55$^{0.56}_{0.53}$ for O ii and Hα, respectively. Our resulting f-factors display a significant positive correlation with the UV attenuation and shallower or not-significant trends with the stellar mass, the SFRTOT, the distance to the main sequence, and the redshift. Finally, our results favour an average nebular attenuation curve similar in shape to the typical dust curve of local starbursts.
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