Les défaillances du numérique : comme matière artistique

La numérisation des images ainsi que l’emploi du numérique pour la création ouvrent de nouvelles possibilités, non seulement pour le stockage du patrimoine culturel, mais également pour la production et la diffusion visuelles, en interaction, bien sûr, avec les autres médiums. Cependant, ces moyens technologiques imposent leurs contraintes et ne recouvrent pas tout à fait les possibilités des moyens plus traditionnels. Au lieu de concevoir ces aspects comme des limites, certains artistes s’interrogent sur la spécificité des nouveaux outils (appareil photo et caméra numériques, numériseur, etc.) et exploitent leurs défaillances comme matière pour leurs expérimentations. En illustrant par des oeuvres récentes déjà renommées ainsi que par des recherches plus jeunes, nous voudrions offrir une réflexion sur l’apport novateur des images numériques qui poursuivent et relancent l’héritage imagier dans lequel elles puisent.The digitalization of images as well as the use of digital systems for their creation open new possibilities, not only for the storage of cultural heritage, but also for production and visual distribution, in interaction with other media. These technological means impose their own constraints without covering all the possibilities offered by the more traditional means. Instead of considering these aspects as limitations, certain artists wonder about the specificity of the new tools trying to use the constraints themselves as a subject for their experiments. By referring to both renowned and less known works, this essay proposes a reflection on the innovative contribution of digital images and their relationship to the visual heritage on which they draw

Control Technology Options and Costs for Reducing Volatile Organic Compounds

In many areas in Europe present ambient concentration levels of ozone are considered as a serious air quality problem. Current scientific understanding of ozone formation mechanisms suggests that only a balanced cut of the major precursor emissions (nitrogen oxides and volatile organic compounds) will effectively lead to a decline of ozone concentrations over larger areas. Consequently, a systematic framework will be required to explore various strategies to reduce exposure of human beings and sensitive ecosystems to elevated ozone concentrations and to identify cost-effective approaches. Such an integrated assessment has to incorporate information on emission sources, the technical potential and the costs of emission reduction measures as well as an understanding of the chemical processes influencing ozone formation. This paper provides an initial overview on the available information material and associated costs of the major options for controlling emissions of volatile organic compounds. Thereby, it makes an important contribution to the ongoing development of a tool for the integrated assessment of the tropospheric ozone problem

Ω−\Omega^- and Ωˉ+\bar\Omega^+ production in Au+Au collisions at sNN\sqrt{s_{NN}} = 130 and 200 GeV

Mid-rapidity Omega and anti-Omega production in Au+Au collisions at RHIC is studied with the STAR experiment. We report preliminary results on yields and spectra at $\sqrt{s_{NN}}$ = 130 and 200 GeV. Production relative to negatively charged hadrons (h-) as well as thermal freeze-out and collective expansion are discussed.Comment: 4 pages, 5 figures, 1 table, Contribution to Quark Matter 2002, Nantes, France, July 200

Deep optical observations of the gamma-ray pulsar PSR J0007+7303 in the CTA 1 supernova remnant

The Fermi Large Area Telescope (LAT) discovered the time signature of a radio-silent pulsar coincident with RX J0007.0+7302, a plerion-like X-ray source at the centre of the CTA 1 supernova remnant. The inferred timing parameters of the gamma-ray pulsar PSR J0007+7303 (P=315.8 ms; dot{P}\sim3.6 10^{-13} s s^{-1}) point to a Vela-like neutron star, with an age comparable to that of CTA 1. The PSR J0007+7303 low distance (\sim 1.4 kpc), interstellar absorption (A_V\sim 1.6), and relatively high energy loss rate (dot{E} \sim4.5 10^{35} erg s^{-1}), make it a suitable candidate for an optical follow-up. Here, we present deep optical observations of PSR J0007+7303. The pulsar is not detected in the Gran Telescopio Canarias (GTC) images down to a limit of r'\sim 27.6 (3 sigma), the deepest ever obtained for this pulsar, while William Herschel Telescope (WHT) images yield a limit of V \sim 26.9. Our r'-band limit corresponds to an optical emission efficiency \eta_{opt}= L_{opt}/dot{E} < 9.4 10^{-8}. This limit is more constraining than those derived for other Vela-like pulsars, but is still above the measured optical efficiency of the Vela pulsar. We compared the optical upper limits with the extrapolation of the XMM-Newton X-ray spectrum and found that the optical emission is compatible with the extrapolation of the X-ray power-law component, at variance with what is observed, e.g. in the Vela pulsar.Comment: 5 pages, 3 figures, accepted for publication on MNRA

Descobreixen un nou sistema binari de raigs-gamma a la nostra galàxia

L'equip de col∙laboració del telescopi espacial Fermi-LAT, integrat entre altres pels científics de l'Institut de Ciències de l'Espai (CSIC-IEEC), amb seu a la UAB, Andrea Caliandro, Daniela Hadasch i Diego Torres, ha descobert un nou sistema binari de raigs gamma en els voltants del centre Galàctic. El descobriment ha merescut la publicació de l'estudi a la prestigiosa revista Science ja que a dia d'avui, només es coneixen uns quants sistemes que emeten en raigs gamma.El equipo de colaboración del telescopio espacial Fermi-LAT, integrado entre otros por los científicos del Instituto de Ciencias del Espacio (CSIC-IEEC), ubicado en el campus de la UAB, Andrea Caliandro, Daniela Hadasch y Diego Torres, han descubierto un nuevo sistema binario de rayos gamma en los inmediaciones del Centro Galáctico tal descubrimiento ha merecido la publicación del estudio en la prestigiosa revista Science ya que a día de hoy, solo se conocen un puñado de sistemas que emiten en rayos gamma

Gamma-ray flare activity from PSR B1259-63 during 2014 periastron passage and comparison to its 2010 passage

PSR B1259-63/LS 2883 is a gamma-ray binary system containing a radio pulsar in a highly elliptical ~3.4-year orbit around a Be star. In its 2010 periastron passage, multiwavelength emission from radio to TeV was observed, as well as an unexpected GeV flare measured by the Fermi Large Area Telescope (LAT). Here, we report the results of LAT monitoring of PSR B1259-63 during its most recent 2014 periastron passage. We compare the gamma-ray behavior in this periastron with the former in 2010 and find that PSR B1259-63 shows a recurrent GeV flare. The similarities and differences in the phenomenology of both periastron passages are discussed.Comment: 6 pages, 5 figures, ApJ, in press. arXiv admin note: text overlap with arXiv:1504.0634