"Spoon-feeding" an AGN

Tidal disruption events (TDEs) occur when a star, passing too close to a massive black hole, is ripped apart by tidal forces. A less dramatic event occurs if the star orbits just outside the tidal radius, resulting in a mild stripping of mass. Thus, if a star orbits a central black hole on one of these bound eccentric orbits, weaker outbursts will occur recurring every orbital period. Thanks to five Swift observations, we observed a recent flare from the close by (92 Mpc) galaxy IC 3599, where a possible TDE was already observed in December 1990 during the Rosat All-Sky Survey. By light curve modeling and spectral fitting, we account for all these events as the non-disruptive tidal stripping of a single star into a 9.5 yr highly eccentric bound orbit. This is the first example of periodic partial tidal disruptions, possibly spoon-feeding the central black hole.Comment: 7 pages, 3 figures, to appear in "Swift:10 years of discovery", Proceedings of Scienc

Consumer guide to competition : a practical handbook

French version available in IDRC Digital Library: Guide du consommateur sur la concurrence : un manuel pratiqu

Concurrence : guide pratique à l'usage des consommateurs

Version anglaise disponible dans la Bibliothèque numérique du CRDI: Consumer guide to competition : a practical handboo

NuQKD: A Modular Quantum Key Distribution Simulation Framework for Engineering Applications

An experimental Quantum Key Distribution (QKD) implementation requires advanced costly hardware, unavailable in most research environments, making protocol testing and performance evaluation complicated. Historically, this has been a major motivation for the development of QKD simulation frameworks, to allow researchers to obtain insight before proceeding into practical implementations. Several simulators have been introduced over the recent years. However, only four are publicly available, only one of which models equipment imperfections. Currently, no open-source simulator includes all following capabilities: channel attenuation modelling, equipment imperfections and effect on key rates, estimation of elapsed time during quantum channel processes, use of truly random binary sequences for qubits and measurement bases, shared-bit fraction customization. In this paper, we present NuQKD, an open-source modular, intuitive simulator, featuring all the above capabilities. NuQKD establishes communication between two computer terminals, accepts custom inputs (iterations, raw key size, interception rate etc.) and evaluates the sifted key length, Quantum Bit Error Rate (QBER), elapsed communication time and more). NuQKD capabilities include optical fiber and free-space simulation, modeling of equipment/channel imperfections, bitstrings from True Random Number Generator, modular design and automated evaluation of performance metrics. We expect NuQKD to enable convenient and accurate representation of actual experimental conditions

A self-learning case and rule-based reasoning algorithm for intelligent technology evaluation and selection [Abstract]

This research programme proposes to fulfill the existing gap in knowledge by providing an experience-oriented decision algorithm to solve technology selection problems based on cases and expert’s experience. The approach adopts historical case-based data to extract rules through the ID3 rule induction algorithm. The decision model integrates a rule induction approach in a rule-based knowledge system and database management system to support automated knowledge mining and usage. The adoption of a pair-wise comparison algorithm within the similarity index assists in relating the importance of the criteria within the knowledgebases reasoner. A series of historical and new solutions are presented in a scoring index based on the requirements of a new case