Online classification for time-domain astronomy

The advent of synoptic sky surveys has spurred the development of techniques for real-time classification of astronomical sources in order to ensure timely follow-up with appropriate instruments. Previous work has focused on algorithm selection or improved light curve representations, and naively convert light curves into structured feature sets without regard for the time span or phase of the light curves. In this paper, we highlight the violation of a fundamental machine learning assumption that occurs when archival light curves with long observational time spans are used to train classifiers that are applied to light curves with fewer observations. We propose two solutions to deal with the mismatch in the time spans of training and test light curves. The first is the use of classifier committees where each classifier is trained on light curves of different observational time spans. Only the committee member whose training set matches the test light curve time span is invoked for classification. The second solution uses hierarchical classifiers that are able to predict source types both individually and by sub-group, so that the user can trade-off an earlier, more robust classification with classification granularity. We test both methods using light curves from the MACHO survey, and demonstrate their usefulness in improving performance over similar methods that naively train on all available archival data.Comment: Astroinformatics workshop, IEEE International Conference on Data Mining 201

Sub-arcsecond CO(1-0) and CO(2-1) observations of the ultraluminous infrared galaxy IRAS 10190+1322

We present the results of high resolution mapping of the CO(1-0) and CO(2-1) emission of the ultraluminous infrared galaxy (ULIRG) IRAS 10190+1322, with the IRAM interferometer, down to an angular resolution of ~0.3 arcsec. This object is composed of two interacting galaxies with a projected nuclear separation of 6 kpc, and was selected to analyze the physical and dynamical properties of the molecular gas in each galaxy in order to study the conditions that lead a galaxy pair to become ultraluminous in the infrared. With the exception of Arp 220, the closest ULIRG, this is the first time that the CO emission is morphologically and kinematically resolved in the two interacting galaxies of a ULIRG system. In one of the galaxies the molecular gas is highly concentrated, distributed in a circumnuclear disk of 1.7 kpc in size. The molecular gas in the presumably less infrared luminous galaxy is distributed in a more extended disk of 7.4 kpc. The molecular gas mass accounts for ~10% of the dynamical mass in each galaxy. Both objects are rich enough in molecular gas, Mgas ~ 4 10^9 Msun, as to experience an infrared ultraluminous phase.Comment: 4 pages, 3 figures. Accepted for publication in A&A Letters Special Issue for the new extended configuration of the Plateau de Bure Interferomete

LANSIM and its applications to distributed EMS

Distributed energy management systems (EMS) open up a host of alternative design options. Simulation plays an important role in evaluating performance and in comparing alternative designs. Currently all the proposed distributed EMSs are local area network (LAN)-based. A LAN simulator, LANSIM, has been developed. To illustrate the application of LANSIM, comparisons are made with different distributed EMS configurations, different LAN technologies (Ethernet and FDDI), and different Ethernet implementations.published_or_final_versio

Radio detections of southern ultracool dwarfs

We report the results of a volume-limited survey using the Australia Telescope Compact Array to search for transient and quiescent radio emission from 15 Southern hemisphere ultracool dwarfs. We detect radio emission from 2MASSW J0004348-404405 increasing the number of radio loud ultracool dwarfs to 22. We also observe radio emission from 2MASS J10481463-3956062 and 2MASSI J0339352-352544, two sources with previous radio detections. The radio emission from the three detected sources shows no variability or flare emission. Modelling this quiescent emission we find that it is consistent with optically thin gyrosynchrotron emission from a magnetosphere with an emitting region radius of (1-2)R*, magnetic field inclination 20°-80°, field strength ~10-200 G, and power-law electron density ~104-108cm-3. Additionally, we place upper limits on four ultracool dwarfs with no previous radio observations. This increases the number of ultracool dwarfs studied at radio frequencies to 222. Analysing general trends of the radio emission for this sample of 15 sources, we find that the radio activity increases for later spectral types and more rapidly rotating objects. Furthermore, comparing the ratio of the radio to X-ray luminosities for these sources, we find 2MASS J10481463-3956062 and 2MASSI J0339352-352544 violate the Güdel-Benz relation by more than two orders of magnitude

Is There Light at the Ends of the Tunnel? Wireless Sensor Networks for Adaptive Lighting in Road Tunnels

Existing deployments of wireless sensor networks (WSNs) are often conceived as stand-alone monitoring tools. In this paper, we report instead on a deployment where the WSN is a key component of a closed-loop control system for adaptive lighting in operational road tunnels. WSN nodes along the tunnel walls report light readings to a control station, which closes the loop by setting the intensity of lamps to match a legislated curve. The ability to match dynamically the lighting levels to the actual environmental conditions improves the tunnel safety and reduces its power consumption. The use of WSNs in a closed-loop system, combined with the real-world, harsh setting of operational road tunnels, induces tighter requirements on the quality and timeliness of sensed data, as well as on the reliability and lifetime of the network. In this work, we test to what extent mainstream WSN technology meets these challenges, using a dedicated design that however relies on wellestablished techniques. The paper describes the hw/sw architecture we devised by focusing on the WSN component, and analyzes its performance through experiments in a real, operational tunnel

A prototypical small-molecule modulator uncouples mitochondria in response to endogenous hydrogen peroxide production

A high membrane potential across the mitochondrial inner membrane leads to the production of the reactive oxygen species (ROS) implicated in aging and age-related diseases. A prototypical drug for the correction of this type of mitochondrial dysfunction is presented. MitoDNP-SUM accumulates in mitochondria in response to the membrane potential due to its mitochondria-targeting alkyltriphenylphosphonium (TPP) cation and is uncaged by endogenous hydrogen peroxide to release the mitochondrial uncoupler, 2,4-dinitrophenol (DNP). DNP is known to reduce the high membrane potential responsible for the production of ROS. The approach potentially represents a general method for the delivery of drugs to the mitochondrial matrix through mitochondria targeting and H2O2-induced uncaging

Physiological roles of pyruvate ferredoxin oxidoreductase and pyruvate formate-lyase in Thermoanaerobacterium saccharolyticum JW/SL-YS485

Background: Thermoanaerobacter saccharolyticum is a thermophilic microorganism that has been engineered to produce ethanol at high titer (30–70 g/L) and greater than 90 % theoretical yield. However, few genes involved in pyruvate to ethanol production pathway have been unambiguously identified. In T. saccharolyticum, the products of six putative pfor gene clusters and one pfl gene may be responsible for the conversion of pyruvate to acetyl-CoA. To gain insights into the physiological roles of PFOR and PFL, we studied the effect of deletions of several genes thought to encode these activities. Results: It was found that pyruvate ferredoxin oxidoreductase enzyme (PFOR) is encoded by the pforA gene and plays a key role in pyruvate dissimilation. We further demonstrated that pyruvate formate-lyase activity (PFL) is encoded by the pfl gene. Although the pfl gene is normally expressed at low levels, it is crucial for biosynthesis in T. saccharolyticum. In pforA deletion strains, pfl expression increased and was able to partially compensate for the loss of PFOR activity. Deletion of both pforA and pfl resulted in a strain that required acetate and formate for growth and produced lactate as the primary fermentation product, achieving 88 % theoretical lactate yield. Conclusion: PFOR encoded by Tsac_0046 and PFL encoded by Tsac_0628 are only two routes for converting pyruvate to acetyl-CoA in T. saccharolyticum. The physiological role of PFOR is pyruvate dissimilation, whereas that of PFL is supplying C1 units for biosynthesis

Automating intention mining

Dataset available at https://github.com/tkdsheep/Intention-Mining-TSE</p