Radio light curves during the passage of cloud G2 near Sgr A*

We calculate radio light curves produced by the bow shock that is likely to form in front of the G2 cloud when it penetrates the accretion disk of Sgr A*. The shock acceleration of the radio-emitting electrons is captured self-consistently by means of first-principles particle-in-cell simulations. We show that the radio luminosity is expected to reach maximum in early 2013, roughly a month after the bow shock crosses the orbit pericenter. We estimate the peak radio flux at 1.4 GHz to be 1.4 - 22 Jy depending on the assumed orbit orientation and parameters. We show that the most promising frequencies for radio observations are in the 0.1<nu<1 GHz range, for which the bow shock emission will be much stronger than the intrinsic radio flux for all the models considered.Comment: 15 pages, 10 figures, accepted for publication in MNRA

Automatic Goal Discovery in Subgoal Monte Carlo Tree Search

Monte Carlo Tree Search (MCTS) is a heuristic search algorithm that can play a wide range of games without requiring any domain-specific knowledge. However, MCTS tends to struggle in very complicated games due to an exponentially increasing branching factor. A promising solution for this problem is to focus the search only on a small fraction of states. Subgoal Monte Carlo Tree Search (S-MCTS) achieves this by using a predefined subgoal-predicate that detects promising states called subgoals. However, not only does this make S-MCTS domain-dependent, but also it is often difficult to define a good predicate. In this paper, we propose using quality diversity (QD) algorithms to detect subgoals in real-time. Furthermore, we show how integrating QD-algorithms into S-MCTS significantly improves its performance in the Physical Travelling Salesmen Problem without requiring any domain-specific knowledge

Particle Acceleration in Pulsar Wind Nebulae: PIC modelling

We discuss the role of particle-in-cell (PIC) simulations in unveiling the origin of the emitting particles in PWNe. After describing the basics of the PIC technique, we summarize its implications for the quiescent and the flaring emission of the Crab Nebula, as a prototype of PWNe. A consensus seems to be emerging that, in addition to the standard scenario of particle acceleration via the Fermi process at the termination shock of the pulsar wind, magnetic reconnection in the wind, at the termination shock and in the Nebula plays a major role in powering the multi-wavelength signatures of PWNe.Comment: 32 pages, 16 figures, to appear in the book "Modelling Nebulae" edited by D. Torres for Springer, based on the invited contributions to the workshop held in Sant Cugat (Barcelona), June 14-17, 201

Analysis of Odorous VOCs using TD-GC-MS/FID/PFPD: Development and Applications to Real Samples

This work aims to present the applicability of a gas chromatograph equipped with three detectors for the analysis of odorous mixtures. An Agilent gas chromatograph (mod. 8890), equipped with a mass spectrometer (Agilent 5977B MSD), a Flame Ionization Detector (FID, Agilent) and a Pulsed Flame Photometric Detector (PFPD, OI Analytical mod. 5833) was adopted, obtaining simultaneous acquisition with MS, FID and PFPD detectors. The splitting of the sample into the three detectors was carried out at the end of the chromatographic column, by a capillary flow technology splitter (Agilent Splitter CFT). By using this system, it is, therefore, possible to achieve the specific detection and quantification of organic compounds by FID analysis, sulphur compounds by PFPD and the identification of the compounds by MS analysis, via comparison with mass spectra. Based on the preliminary outcomes obtained,the application of this system in the analysis of odour samples enabled the determination of specific classes, even in traces: by this, the subsequent identification of these compounds during a single chromatographic run is possible. This combination provides significant time and costs savings in the calibration and analysis of chromatographic data