520 research outputs found
L'effet CSI: état de l'art sur un phénomène aux multiples facettes
Depuis son lancement en 2000, la série policière "Les Experts" ("CSI : Crime Scene Investigations" en version originale) a été l'une des séries les plus populaires dans son genre tant aux Etats-Unis qu'ailleurs dans le monde. En raison de la représentation idéalisée la science forensique véhiculée au fil des épisodes, certains acteurs juridiques américains on exprimé, par l'intermédiaire de la presse populaire, l'inquiétude selon laquelle de telles séries puissent hausser les attentes des jurés vis-à-vis des indices matériels présentés au tribunal. Le terme "effet CSI" a ainsi été créé afin de désigner l'influence des séries de genre forensique, particulièrement "Les experts", sur la prise de décision des jurés lors des procès. Par la suite, l'utilisation de ce terme s'est étendue aux autres acteurs sociaux et juridiques.
Cet article a pour but de présenter en détail l' "effet CSI" par le biais d'une recherche bibliographique des travaux effectués sur le sujet. La typologie des principaux effets décrits dans la littérature, l'évolution spatio-temporelle de l'emploi de ce terme, ainsi que les principaux points de vue et constats sont présentés.
Cette compilation bibliographique révèle que les principaux champs de recherche de l' "effet CSI" peuvent changer en fonction de la zone géographique. D'une manière générale, il ressort que les séries policières peuvent être vecteurs d'informations propres à modifier la perception de la science forensique par le grand public mais qu'elles ne sont pas les seuls médias à produire une image réaliste de la criminalité et du système de justice pénale. Ces sources de divertissement peuvent quelquefois être éducatives mais peuvent également avoir pour effet de provoquer une hausse des attentes du citoyen ordinaire envers la police technique et l'indice matériel, sans pour autant constituer une menace pour le système de justice pénale
INTEGRAL detection of hard X-rays from NGC 6334: Nonthermal emission from colliding winds or an AGN?
We report the detection of hard X-ray emission from the field of the
star-forming region NGC 6334 with the the International Gamma-Ray Astrophysics
Laboratory INTEGRAL. The JEM-X monitor and ISGRI imager aboard INTEGRAL and
Chandra ACIS imager were used to construct 3-80 keV images and spectra of NGC
6334. The 3-10 keV and 10-35 keV images made with JEM-X show a complex
structure of extended emission from NGC 6334. The ISGRI source detected in the
energy ranges 20-40 keV and 40-80 keV coincides with the NGC 6334 ridge. The
20-60 keV flux from the source is (1.8+-0.37)*10(-11) erg cm(-2) s(-1).
Spectral analysis of the source revealed a hard power-law component with a
photon index about 1. The observed X-ray fluxes are in agreement with
extrapolations of X-ray imaging observations of NGC 6334 by Chandra ACIS and
ASCA GIS. The X-ray data are consistent with two very different physical
models. A probable scenario is emission from a heavily absorbed, compact and
hard Chandra source that is associated with the AGN candidate radio source NGC
6334B. Another possible model is the extended Chandra source of nonthermal
emission from NGC 6334 that can also account for the hard X-ray emission
observed by INTEGRAL. The origin of the emission in this scenario is due to
electron acceleration in energetic outflows from massive early type stars. The
possibility of emission from a young supernova remnant, as suggested by earlier
infrared observations of NGC 6334, is constrained by the non-detection of 44Ti
lines.Comment: 8 pages, 8 figures, Astronomy and Astrophysics (in press
Extracting Structural Information of a Heteropolymer from Force-Extension Curves
We present a theory for the reverse analysis on the sequence information of a
single H/P two-letter random hetero-polymer (RHP) from its force-extension(f-z)
curves during quasi static stretching. Upon stretching of a self-assembled RHP,
it undergoes several structural transitions. The typical elastic response of a
hetero-polymeric globule is a set of overlapping saw-tooth patterns. With
consideration of the height and the position of the overlapping saw-tooth
shape, we analyze the possibility of extracting the binding energies of the
internal domains and the corresponding block sizes of the contributing
conformations.Comment: 5 figures 7 page
Dynamics of the Lyman alpha and C IV emitting gas in 3C 273
In this paper we study the variability properties of the Lyman alpha and C IV
emission lines in 3C273 using archival IUE observations. Our data show for the
first time the existence of variability on time scales of several years. We
study the spatial distribution and the velocity field of the emitting gas by
performing detailed analyses on the line variability using correlations, 1D and
2D response functions, and principal component analysis. In both lines we find
evidence for two components, one which has the dynamic properties of gas in
Keplerian motion around a black hole with a mass of the order of 10^9 Mo, and
one which is characterized by high, blue-shifted velocities at large lag. There
is no indication of the presence of optically thick emission medium neither in
the Lya, nor in the Civ response functions. The component characterized by
blue-shifted velocities, which is comparatively much stronger in Civ than in
Lya, is more or less compatible with being the result of gas falling towards
the central black hole with free-fall acceleration. We propose however that the
line emission at high, blue-shifted velocities is better explained in terms of
entrainment of gas clouds by the jet. This gas is therefore probably
collisionally excited as a result of heating due to the intense infrared
radiation from the jet, which would explain the strength of this component in
Civ relative to Lya. This phenomenon might be a signature of disk-jet
interaction.Comment: 16 pages, 10 figures. Accepted for publication in ApJ. Uses aaste
Very Extended X-ray and H-alpha Emission in M82: Implications for the Superwind Phenomenon
We discuss the properties and implications of a 3.7x0.9 kpc region of
spatially-coincident X-ray and H-alpha emission about 11.6 kpc to the north of
the galaxy M82 previously discussed by Devine and Bally (1999). The PSPC X-ray
spectrum is fit by thermal plasma (kT=0.80+-0.17 keV) absorbed by only the
Galactic foreground column density. We evaluate the relationship of the
X-ray/H-alpha ridge to the M82 superwind. The main properties of the X-ray
emission can all be explained as being due to shock-heating driven as the
superwind encounters a massive ionized cloud in the halo of M82. This encounter
drives a slow shock into the cloud, which contributes to the excitation of the
observed H-alpha emission. At the same time, a fast bow-shock develops in the
superwind just upstream of the cloud, and this produces the observed X-ray
emission. This interpretation would imply that the superwind has an outflow
speed of roughly 800 km/s, consistent with indirect estimates based on its
general X-ray properties and the kinematics of the inner kpc-scale region of
H-alpha filaments. The gas in the M82 ridge is roughly two orders-of-magnitude
hotter than the minimum "escape temperature" at this radius, so this gas will
not be retained by M82.
(abridged)Comment: 24 pages (latex), 3 figures (2 gif files and one postscript),
accepted for publication in Part 1 of The Astrophysical Journa
30 years of multi-wavelength observations of 3C 273
We present a wide multi-wavelength database of most observations of the
quasar 3C 273 obtained during the last 30 years. This database is the most
complete set of observations available for an active galactic nucleus (AGN). It
contains nearly 20'000 observations grouped together into 70 light curves
covering 16 orders of magnitude in frequency from the radio to the gamma-ray
domain.
The database is constituted of many previously unpublished observations and
of most publicly available data gathered in the literature and on the World
Wide Web (WWW). It is complete to the best of our knowledge, except in the
optical (UBV) domain where we chose not to add all observations from the
literature. In addition to the photometric data, we present the spectra of 3C
273 obtained by the International Ultraviolet Explorer (IUE) satellite. In the
X-ray domain, we used the spectral fit parameters from the literature to
construct the light curves.
Apart from describing the data, we show the most representative light curves
and the average spectrum of 3C 273. The database is available on the WWW in a
homogeneous and clear form and we wish to update it regularly by adding new
observations.Comment: 12 pages, 6 figures, to be published in A&AS, data available at:
http://obswww.unige.ch/3c273
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