2,890 research outputs found
La mise en ligne des informations liées aux risques : véritable outil de prévention ou alibi ?
International audienceCet article fait le point sur la mise en ligne des informations liées à deux types de risques (technologiques -inondations), à caractÚre industriel ou naturel, afin de déterminer si cette mise à disposition des informations peut constituer un véritable outil de prévention ou si elle ne représente, en fait, qu'un simple alibi pour les pouvoirs publics
Exocomets in the circumstellar gas disk of HD 172555
The source HD172555 is a young A7V star surrounded by a debris disk with a
gaseous component. Here, we present the detection of variable absorption
features detected simultaneously in the Ca II K and H doublet lines (at 3,933
and 3,968 Angstrom). We identified the presence of these absorption signatures
at four different epochs in the 129 HARPS high-resolution spectra gathered
between 2004 and 2011. These transient absorption features are most likely due
to Falling Evaporating Bodies (FEBs, or exocomets) that produce absorbing gas
observed transiting in front of the central star. We also detect a stable Ca II
absorption component at the star's radial velocity. With no corresponding
detection in the Na I line, the resulting very low upper limit for the NaI/CaII
ratio suggests that this absorption is due to circumstellar gas.Comment: Accepted for publication in Astronomy&Astrophysics Letter
Detection of seismic site effects: Development of experimental methods and application to the city of Nice
Les effets de site reprĂ©sentent un enjeu important pour la prĂ©vention parasismique, puisquâils peuvent aggraver considĂ©rablement les dommages lors dâun sĂ©isme. La connaissance de la rĂ©ponse des sols aux sĂ©ismes permet dâadapter la rĂ©glementation parasismique Ă ces contraintes lors de lâĂ©laboration de microzonages et de Plan de PrĂ©vention des risques. Les mĂ©thodes expĂ©rimentales de dĂ©termination des effets de site visent Ă obtenir les paramĂštres de lâamplification sismique par la mesure de sĂ©ismes ou de bruit de fond sismique. Cet article prĂ©sente les principaux rĂ©sultats obtenus jusquâen 2005 par lâERA « Risque sismique » dans la mise au point de ces techniques et leur application comparĂ©e sur la ville de Nice. Cette ville a effectivement constituĂ© le principal chantier dâapplication grĂące Ă de multiples campagnes dâenregistrements sismiques. De nombreux sĂ©ismes ont dâabord Ă©tĂ© analysĂ©s par la mĂ©thode des fonctions de transfert. La mĂ©thode « H/V bruit de fond » a Ă©tĂ© appliquĂ©e sur plus de 600 points et les rĂ©sultats interpolĂ©s spatialement. Un modĂšle gĂ©otechnique du sous-sol a ensuite permis de comparer les rĂ©sultats obtenus avec la gĂ©ologie et des simulations numĂ©riques de la propagation des ondes. La complĂ©mentaritĂ© des mĂ©thodes et leurs atouts respectifs sont mis en valeur sur ce territoire Ă fort enjeu.Site effects represent a critical challenge in the field of earthquake prevention since these effects are capable of seriously exacerbating damage whenever an earthquake strikes. Knowledge of the soil response to seismic activity allows adapting earthquake protection regulations to better incorporate these constraints during the process of defining microzones and producing the Risk Prevention Plan. The experimental methods employed to determine site effects seek to obtain seismic amplification parameters by means of measuring earthquakes or seismic background noise. This article presents the main set of results derived until 2005 by the âSeismic riskâ ERA research team during development of these techniques as well as their comparative application to Nice, a city that has constituted the main field application site thanks to its hosting of multiple seismic recording campaigns. For starters, many earthquakes have been analyzed according to the transfer function method. The âHorizontal/Vertical background noiseâ method was in particular applied to over 600 points, with results being spatially interpolated. A geotechnical model of the subsoil then served to compare the results output with both the geology and numerical simulations of wave propagation. The complementarity of methods and their respective advantages are highlighted in this seismically-active setting
Postnatal development of the astrocyte perivascular MLC1/GlialCAM complex defines a temporal window for the gliovascular unit maturation
International audienc
Does the pension systemâs income statement really matter? A proposal for an NDC scheme with disability and minimum pension benefits
This paper develops an accounting model for monitoring the
solvency of a notional defined contribution (NDC) pension
scheme with disability and minimum pension benefits. Using the
annual report of the Swedish pension system as a benchmark,
the âSwedishâ actuarial balance is extended by adding an income
statement fully explaining the reasons behind the changes in the
systemâs solvency by type of benefit. In line with the reference
model, assets and liabilities are measured at present value at
each reporting date, and in each period, included as income or
expenses on the Income statement. This accounting framework
integrates both contributory and social aspects of public pensions
and discloses the real cost of the disability contingency and the
redistribution through minimum pensions. Apart from Sweden,
this proposal could be especially interesting for improving the
reporting of public pensions in countries such as Poland, Italy,
Latvia and Norway
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