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Search Results: 1 - 10 of 454 matches for " Padovani "
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Premières impressions sur l'Exposition universelle de Shanghai
Florence Padovani
EchoGéo , 2010,
Abstract: L’article explique d’abord le processus d’organisation d’une exposition universelle, avant de montrer comment le montage fait à Shanghai présente plus la Chine face à son histoire et à sa population plut t que la Chine face au monde. Grande fête populaire l’Expo Shanghai 2010 ne fournit que peu de pistes pour l’aménagement des villes du futur. First the article explains what are the different processes to organize a World Exposition, then it shows that in Shanghai it was done in such a way that the emphasis was more on China facing its own history and its own population rather than China facing the world. Shanghai Expo 2010 was a huge popular fair which did not provide many hints for the future urban planning.
Session Types at the Mirror
Luca Padovani
Electronic Proceedings in Theoretical Computer Science , 2009, DOI: 10.4204/eptcs.12.5
Abstract: We (re)define session types as projections of process behaviors with respect to the communication channels they use. In this setting, we give session types a semantics based on fair testing. The outcome is a unified theory of behavioral types that shares common aspects with conversation types and that encompass features of both dyadic and multi-party session types. The point of view we provide sheds light on the nature of session types and gives us a chance to reason about them in a framework where every notion, from well-typedness to the subtyping relation between session types, is semantically -rather than syntactically- grounded.
Session Types = Intersection Types + Union Types
Luca Padovani
Electronic Proceedings in Theoretical Computer Science , 2011, DOI: 10.4204/eptcs.45.6
Abstract: We propose a semantically grounded theory of session types which relies on intersection and union types. We argue that intersection and union types are natural candidates for modeling branching points in session types and we show that the resulting theory overcomes some important defects of related behavioral theories. In particular, intersections and unions provide a native solution to the problem of computing joins and meets of session types. Also, the subtyping relation turns out to be a pre-congruence, while this is not always the case in related behavioral theories.
Towards a Better Understanding of Active Galactic Nuclei
Paolo Padovani
Physics , 1996,
Abstract: Active Galactic Nuclei (AGN) are ideal sources for multi-wavelength studies as their emission can cover almost 20 orders of magnitude in frequency from the radio to the gamma-ray band. After reviewing their basic properties, I will assess how well we know the multifrequency spectra of AGN as a class. I will then briefly illustrate how currently available and forthcoming sky surveys will help in addressing some of the open questions of AGN studies. Finally, an analysis of the problem of the missing Type 2 QSO will exemplify the dangers of monochromatic sky surveys for AGN.
Unified Schemes for Radio-loud AGN: Recent Results
Paolo Padovani
Physics , 1997,
Abstract: After briefly summarizing the main tenets of unified schemes of Active Galactic Nuclei, I review some recent results in the field of unification of radio-loud sources, both for the low-luminosity (BL Lacs and Fanaroff-Riley type I radio galaxies) and high-luminosity (radio quasars and Fanaroff-Riley type II radio galaxies) populations.
WFXT synergies with next generation radio surveys
P. Padovani
Physics , 2010,
Abstract: I highlight the synergies of the Wide Field X-ray Telescope (WFXT) with the next generation radio surveys, including those to be obtained with the Australian Square Kilometre Array Pathfinder and the Square Kilometre Array, and discuss the overlap between the X-ray and radio source populations. WFXT will benefit greatly from the availability of deep radio catalogues with very high astrometric precision, while on the other hand WFXT data will be vital for the identification of faint radio sources down to ~ 50 microJy.
Unified Schemes and the two Classes of BL Lacs
Paolo Padovani
Physics , 1999,
Abstract: I briefly summarize the main tenets of unified schemes of BL Lacs and low-luminosity radio galaxies, discussing in particular the evolution of this field after the Como 1988 meeting. I also examine some of the open problems and complications of the simplest scheme. Finally, the question of the existence of two classes of BL Lacs and our related change of perspective in the past few years are also addressed.
High Energy Emission from AGN and Unified Schemes
Paolo Padovani
Physics , 1999,
Abstract: Active Galactic Nuclei (AGN) are now known to be strong gamma-ray emitters. After briefly describing AGN classification and the main ideas behind unified schemes, I summarize the main properties of blazars (that is BL Lacs and flat-spectrum radio quasars) and their connection with relativistic beaming. Finally, I address the question of why blazars, despite being extreme and very rare objects, are the only AGN detected at high (E > 100 MeV) energies, and touch upon the relevance of TeV astronomy for AGN research.
Gamma-ray Emitting AGN and Unified Schemes
Paolo Padovani
Physics , 1997,
Abstract: Active Galactic Nuclei (AGN) are now known to be strong gamma-ray emitters. After briefly describing the different classes of AGN and the basic tenets of unified schemes, I discuss the role of blazars (that is BL Lacs and flat-spectrum radio quasars) as gamma-ray sources. The main properties of blazars and their connection with relativistic beaming are then summarized. Finally, I address the question of why blazars, despite being extreme and very rare objects, are the only AGN detected at very high (E > 100 MeV) energies, and touch upon the relevance of TeV astronomy for AGN research.
The MicroJy and NanoJy Radio Sky: Source Population and Multi-wavelength Properties
Paolo Padovani
Physics , 2010, DOI: 10.1111/j.1365-2966.2010.17789.x
Abstract: I present simple but robust estimates of the types of sources making up the faint, sub-microJy radio sky. These include, not surprisingly, star-forming galaxies and radio-quiet AGN but also two "new" populations, that is low radio power ellipticals and dwarf galaxies, the latter likely constituting the most numerous component of the radio sky. I then estimate for the first time the X-ray, optical, and mid-infrared fluxes these objects are likely to have, which are very important for source identification and the synergy between the upcoming SKA and its various pathfinders with future missions in other bands. On large areas of the sky the SKA, and any other radio telescope producing surveys down to at least the microJy level, will go deeper than all currently planned (and past) sky surveys, with the possible exception of the optical ones from PAN-STARRS and the LSST. SPICA, JWST, and in particular the Extremely Large Telescopes (ELTs) will be a match to the next generation radio telescopes but only on small areas and above ~ 0.1 - 1 microJy (at 1.4 GHz), while even IXO will only be able to detect a small (tiny) fraction of the microJy (nanoJy) population in the X-rays. On the other hand, most sources from currently planned all-sky surveys, with the likely exception of the optical ones, will have a radio counterpart within the reach of the SKA. JWST and the ELTs might turn out to be the main, or perhaps even the only, facilities capable of securing optical counterparts and especially redshifts of microJy radio sources. Because of their sensitivity, the SKA and its pathfinders will have a huge impact on a number of topics in extragalactic astronomy including star-formation in galaxies and its co-evolution with supermassive black holes, radio-loudness and radio-quietness in AGN, dwarf galaxies, and the main contributors to the radio background.[ABRIDGED]
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