Abstract
We present the first version of the Automatic Learning for the Rapid Classification of Events (ALeRCE) broker light curve classifier. ALeRCE is currently processing the Zwicky Transient ...Facility (ZTF) alert stream, in preparation for the Vera C. Rubin Observatory. The ALeRCE light curve classifier uses variability features computed from the ZTF alert stream and colors obtained from AllWISE and ZTF photometry. We apply a balanced random forest algorithm with a two-level scheme where the top level classifies each source as periodic, stochastic, or transient, and the bottom level further resolves each of these hierarchical classes among 15 total classes. This classifier corresponds to the first attempt to classify multiple classes of stochastic variables (including core- and host-dominated active galactic nuclei, blazars, young stellar objects, and cataclysmic variables) in addition to different classes of periodic and transient sources, using real data. We created a labeled set using various public catalogs (such as the Catalina Surveys and Gaia DR2 variable stars catalogs, and the Million Quasars catalog), and we classify all objects with ≥6
g
-band or ≥6
r
-band detections in ZTF (868,371 sources as of 2020 June 9), providing updated classifications for sources with new alerts every day. For the top level we obtain macro-averaged precision and recall scores of 0.96 and 0.99, respectively, and for the bottom level we obtain macro-averaged precision and recall scores of 0.57 and 0.76, respectively. Updated classifications from the light curve classifier can be found at the ALeRCE Explorer website (
http://alerce.online
).
Since 2012, we have investigated a stratigraphic section encompassing the late Eocene–earliest Oligocene interval at Shapaja (Tarapoto area, Peruvian Amazonia, ca. 7°S), through paleontological and ...geological fieldwork. The measured sedimentary series (120 m-thick West plus 90 m-thick East), assigned to the upper member of the Pozo Formation, records fluvial micro-conglomeratic lenses intercalated with floodplain and evaporite-rich fine red deposits, estuarine/coastal-plain tidally-influenced fine sandstones, and oxbow lake nodule-rich blue clays. This sedimentary shift coincides locally with the demise of the large Eocene coastal-plain wetland known as Pozo System. The late Eocene–early Oligocene Shapaja section was extensively sampled for chemostratigraphy (δ13C on dispersed organic matter and pedogenic carbonate nodules), which in turn allowed for refining the location of the Eocene-Oligocene Transition (EOT) and other climatic events recognized at a global scale (i.e., Oi-1 and Oi-1a). The section has yielded nine fossil localities with plant remains (leaves, wood, charophytes, and palynomorphs), mollusks, decapods, and/or vertebrates (selachians, actinopterygians, lungfishes, amphibians, sauropsids, and mammals), documenting ~130 distinct taxa. Four localities of the upper member of the Pozo Formation at Shapaja predate the EOT, one is clearly within the EOT, while four are earliest/early Oligocene in age. The small leaf impressions found along the Shapaja section could be indicative of dry and/or seasonal conditions for this region throughout and after the EOT. Monkeys, indicative of tropical rainforest environments, are only recorded in a latest Eocene locality (TAR-21). Two biotic turnovers are perceptible in the selachian, metatherian, and rodent communities, well before the EOT ~35–36 Ma and a few hundred thousand years after the EOT ~33 Ma. The latter turnover seems to be primarily related to a global sea-level drop (ichthyofauna: marine-littoral elements replaced by obligate freshwater taxa) and/or the onset of a drier and more seasonal climate in early Oligocene times (terrestrial components). Changes in the structure of the Shapaja paleocommunities were mostly driven by the flexural subsidence during the late Eocene, and then globally driven by the earliest Oligocene climatic deterioration.
•The Shapaja section spans the late Eocene–early Oligocene interval (ca. 36–32.5 Ma).•Micro- and macroremains of 129 plant and animal fossil taxa were recognized.•Two faunal turnovers are recorded on both sides of the Eocene-Oligocene transition.•Shapaja records the earliest occurrence of South American primates and sloth.•Community changes are locally- then globally-driven (late Eocene/earliest Oligocene).
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.
During the late Miocene, the Andean–Amazonian region experienced drastic climatic and environmental changes, notably due to a major phase in the Andean uplift. The fossil record is virtually ...undocumented for this period in the Subandean Zone, where very few palaeoenvironmental and palaeontological investigations have been undertaken. Here, we describe plant remains (pollen, spores, and leaves), microfossils, mollusks, and vertebrates from the Ipururo Formation at Shumanza, San Martín, Peru. Twenty-nine plant families are identified from 164 pollen grains and 89 spores, among them Lycophytes, Monilophytes, and angiosperms (5 monocots and 18 eudicots). The pollen sample notably includes
Grimsdalea magnaclavata
,
Palaeosantalaceaepites cingulatus
,
Echitricolporites spinosus
, and
Fenestrites longispinosus
, pointing to a late Miocene–early Pliocene age for the TAR-27 locality (10.06–3.72 Ma). Leaf impressions, from nearby localities in the same section, document
Malvaciphyllum
sp. (Malvaceae), three morphs resembling Caryocaraceae, Fabaceae, Myrtaceae, and two unidentified ‘Dicotyledonae’ angiosperms. The mollusk assemblage is somewhat reminiscent of early–middle Miocene Pebasian faunas and dominated by gastropods (ampullariids, cochliopid, cerithioid, and planorbids). It also includes sphaeriid and unionoid bivalves. Vertebrate recovery is very poor, with a serrasalmine characiform and unidentified actinopterygian teeth. Fossil assemblages and sedimentary facies consistently testify to the dominance of riverine/alluvial forests and the persistence of a steady lowland rainforest close to the Andes less than 10.1 million years ago, without indication of (1) mangrove/marine environments or (2) high-elevation ranges in the close surroundings of Shumanza by that time. By coupling palynostratigraphy and lithostratigraphy, Shumanza fossil assemblages would be further assigned an early late Miocene age (10.1–ca. 8 Ma).
El diseño de patrones predefinidos está ejecutado con procesamiento de imágenes a partir de un retrato fotográfico, con el cual hemos implementado el método de pantallas nulas por refracción para la ...creación de piezas de arte inmersivas, que implica un espacio donde el público se sumerge en una experiencia visual envolvente de 360 grados. En este trabajo se supone la incidencia de un frente de onda plano en una lente asférica plano-convexa, con el conocimiento del trazo exacto de rayos y la forma de la cáustica, se calcula la posición para colocar un detector CCD donde la intensidad es uniforme y podemos reconstruir el retrato en forma de patrón predefinido. Las imágenes fueron registradas en tiempo real y pueden ser proyectadas en medios digitales desde el montaje experimental. Como resultado final se obtuvo la visualización reconfigurada de un retrato fotográfico a partir de su pantalla nula por refracción y se concluye que la estética de los resultados pueden ser funcionales para su aplicación en piezas de arte inmersivas.
Total enzyme activity of whole viscera, and partial characterization of acidic proteases from Monterey sardine viscera are presented. Major proteolytic activity in alkali (pH 10) and minor activity ...in acid (pH 3) were detected. From purified acidic proteases, six fractions with high activity were selected. One fraction (42) showed one band on SDS–PAGE and two bands on isoelectrofocusing, with pI close to 4.0 and 4.5, respectively. The optimal pH for acidic protease activity was 2.5, with high stability in the acid range and marked loss of activity at neutral and alkaline pH. The optimum temperature was 45 °C, and activity was high at 10 °C, whereas denaturation occurred above 55 °C. Activity was inhibited by Pepstatin A but not by SBTI or EDTA. The general characteristics of these enzymes resemble those of the digestive enzymes of other fish. Because Monterey sardine is abundant in Mexico, it is a potential source for biological reagent production.
Chymotrypsin was isolated from the viscera of Monterey sardine by ammonium sulphate fractionation, gel filtration, and ionic exchange chromatography. The approximate molecular weight was 26,000 and ...its isoelectric point was about 5. Identity as chymotrypsin was established by its catalytic specificity for amide or ester bonds on the synthetic substrates succinyl-
l-ala-ala-pro-
l-pheilalanine-
p-nitroanilide and benzoyl-
l-tyrosine-ethyl-ester, showing esterase activity 3.2-fold higher than amidase. It was inhibited by phenylmethylsulfonyl-fluoride and soybean trypsin inhibitor, partly inhibited by the specific chymotrypsin inhibitor
N-toluenesulfonyl-
l-phenylalanine chloromethyl-ketone, but not inhibited by EDTA or Benzamidine. Chymotrypsin showed its maximum activity at pH 8.0 and 50
°C for the hydrolysis of SAAPNA. The Michaelis–Menten constant was 0.074 mM with a catalysis constant of 18.6 seg
−1, and catalytic efficiency of 252 seg
−1
mM
−1. Results indicated that Monterey sardine chymotrypsin is a good catalyst and could be used as a biotechnological tool in food processing and using sardine industry wastes as a material for production of fine reagents.
We present the first version of the ALeRCE (Automatic Learning for the Rapid Classification of Events) broker light curve classifier. ALeRCE is currently processing the Zwicky Transient Facility ...(ZTF) alert stream, in preparation for the Vera C. Rubin Observatory. The ALeRCE light curve classifier uses variability features computed from the ZTF alert stream, and colors obtained from AllWISE and ZTF photometry. We apply a Balanced Random Forest algorithm with a two-level scheme, where the top level classifies each source as periodic, stochastic, or transient, and the bottom level further resolves each of these hierarchical classes, amongst 15 total classes. This classifier corresponds to the first attempt to classify multiple classes of stochastic variables (including core- and host-dominated active galactic nuclei, blazars, young stellar objects, and cataclysmic variables) in addition to different classes of periodic and transient sources, using real data. We created a labeled set using various public catalogs (such as the Catalina Surveys and {\em Gaia} DR2 variable stars catalogs, and the Million Quasars catalog), and we classify all objects with \(\geq6\) \(g\)-band or \(\geq6\) \(r\)-band detections in ZTF (868,371 sources as of 2020/06/09), providing updated classifications for sources with new alerts every day. For the top level we obtain macro-averaged precision and recall scores of 0.96 and 0.99, respectively, and for the bottom level we obtain macro-averaged precision and recall scores of 0.57 and 0.76, respectively. Updated classifications from the light curve classifier can be found at the \href{http://alerce.online}{ALeRCE Explorer website}.
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.
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