366 research outputs found
Health Information and the Choice of Fish Species: An Experiment Measuring the Impact of Risk and Benefit Information
An experiment was conducted in France to evaluate the impact of health information on consumers\u27 choice between two different types of fish. Successive messages revealing risks (methylmercury) and benefits (omega-3s) of consuming the fish, along with consumption recommendations, were delivered. Results show a significant difference of reaction according to the order and type of information. The information about risks had a larger marginal impact on change in willingness to pay (WTP) than did the information about benefits. While the results show that detailed messages on risks/benefits, including recommendations for nutrition behavior, matter in the modification of WTP, 40% of respondents did not change their initial choices after the revelation of health information
Does Health Information Matter for Modifying Consumption? A Field Experiment Measuring the Impact of Risk Information on Fish Consumption
A field experiment was conducted in France to evaluate the impact of health information on fish consumption. A warning given to the treatment group revealed the risks of methylmercury contamination in fish and also gave consumption recommendations. Using difference-indifferences estimation, we show that this warning led to a significant but relatively weak decrease in fish consumption. However, consumption of the most contaminated fish did not decrease despite advice to avoid consumption of these types of fish. Accompanying questionnaires show that consumers imperfectly memorize the fish species quoted in the warning. The results point to the relatively poor efficacy of a complex health message, despite its use by health agencies around the world
Studying Network Mechanisms Using Intracranial Stimulation in Epileptic Patients
Patients suffering from focal drug-resistant epilepsy who are explored using intracranial electrodes allow to obtain data of exceptional value for studying brain dynamics in correlation with pathophysiological and cognitive processes. Direct electrical stimulation (DES) of cortical regions and axonal tracts in those patients elicits a number of very specific perceptual or behavioral responses, but also abnormal responses due to specific configurations of epileptic networks. Here, we review how anatomo-functional brain connectivity and epilepsy network mechanisms can be assessed from DES responses measured in patients. After a brief summary of mechanisms of action of brain electrical stimulation, we recall the conceptual framework for interpreting DES results in the context of brain connectivity and review how DES can be used for the characterization of functional networks, the identification of the seizure onset zone, the study of brain plasticity mechanisms, and the anticipation of epileptic seizures. This pool of exceptional data may be underexploited by fundamental research on brain connectivity and leaves much to be learned
Rapport sur le suivi morphosédimentaire du sillon de Talbert pour l'année 2015
La prĂ©sente Ă©tude sâinscrit dans la continuitĂ© du suivi topoâmorphologique du Sillon de Talbert initiĂ© en 2003 Ă la demande de la commune de Pleubian et du Conservatoire du Littoral. Lâobjectif est dâanalyser les modalitĂ©s dâĂ©volution de la flĂšche depuis lâenlĂšvement de lâenrochement en 2004 (StĂ©phan et al., 2007, 2008, 2009, 2011, 2012, 2015 ; Fichaut et al., 2010, 2013). Dans le cadre de ce rapport, nous prĂ©sentons les principaux changements morphologiques survenus entre les levĂ©s topographiques effectuĂ©s aux mois de septembre 2014 et septembre 2015 Ă lâĂ©chelledu Sillon. La mĂ©thode que nous avons employĂ©e pour reconstituer la topographie de lâestran respecte en partie le protocole de mesure dĂ©taillĂ© dans nos prĂ©cĂ©dents rapports. Elle sâappuie sur lâacquisition de mesures topographiques au DGPS (type TopCon HiperV) Ă partir dâune station fixe installĂ©e sur la borne IGN situĂ©e sur le sĂ©maphore de CrĂ©acâh Maout, dont les coordonnĂ©es gĂ©odĂ©siques sont accessibles sur le site de lâIGN (www.ign.fr/ rubrique GĂ©odĂ©sie). Toutefois, il faut noter que quelques changements ont Ă©tĂ© introduit cette annĂ©e et nĂ©cessite de faire un nouveau point mĂ©thodologique. Il faut noter que le levĂ© de 2015 fait suite aux grosses tempĂȘtes de lâhiver 2013â 2014. Ce dernier a Ă©tĂ© lâun des plus tempĂ©tueux quâa connu la Bretagne au cours des deux derniĂšres dĂ©cennies. Entre les mois dâoctobre 2013 et de mars 2014, une douzaine de tempĂȘtes majeures se sont succĂ©dĂ© sur les cĂŽtes françaises de lâAtlantique et de la Manche, associant des vents violents, de fortes pluviomĂ©tries et de fortes houles ocĂ©aniques (Blaise et al., 2015). Ce contexte, particuliĂšrement propice au mouvement des sĂ©diments sur le littoral, a entraĂźnĂ© un dĂ©maigrissement de nombreuses plages de Bretagne. La forte frĂ©quence de ces Ă©vĂ©nements durant lâhiver a abouti, Ă plusieurs reprises, Ă la conjonction dâune mer trĂšs agitĂ©e et dâune marĂ©e de viveâeau. Durant les pleines mers, lâaction des vagues a Ă©tĂ© portĂ©e dans les parties hautes de lâestran, rarement atteintes par la mer. ConjuguĂ©e Ă des coefficients de marĂ©e importants et des surcotes significatives, la forte agitation marine a gĂ©nĂ©rĂ© des niveaux dâeau instantanĂ©s trĂšs Ă©levĂ©s. Les vagues ont donc franchi de nombreux cordons de galets. Compte tenu de son exposition aux houles, le Sillon de Talbert a Ă©tĂ© frappĂ© de plein fouet par ces phĂ©nomĂšnes. Toutefois, la comparaison des levĂ©s rĂ©alisĂ©s entre mars 2014 et septembre 2014 a montrĂ© que le cordon Ă©tait en cours de rĂ©gĂ©nĂ©ration postâtempĂȘte, liĂ©e aux conditions mĂ©tĂ©oâocĂ©aniques plus calmes qui ont agi durant cette pĂ©riode (StĂ©phan et al., 2015). Il s'agissait donc de voir si le levĂ© de l'annĂ©e 2015 confirmait ou pas cette tendance Ă la rĂ©gĂ©nĂ©ration du sillon de Talbert
Interface-templated crystal growth in sodium dodecyl sulfate solutions with NaCl
Many ionic surfactants, such as sodium dodecyl sulphate (SDS) crystallize out
of solution if the temperature falls below the crystallization boundary. The
crystallization temperature is impacted by solution properties, and can be
decreased with the addition of salt. We have studied SDS crystallization a t
the liquid/vapor interfaces from solutions at high ionic strength (sodium
chloride). We show that the surfactant crystals at the surface grow from
adsorbed SDS molecules, as evidenced by the preferential orientation of the
crystals identified using grazing incidence X-ray diffraction. We find a unique
timescale f or the crystal growth from the evolution of structure, surface
tension, and visual inspection, which can be controlled through varying the SDS
or NaCl concentrations
Overt speech decoding from cortical activity: a comparison of different linear methods
IntroductionSpeech BCIs aim at reconstructing speech in real time from ongoing cortical activity. Ideal BCIs would need to reconstruct speech audio signal frame by frame on a millisecond-timescale. Such approaches require fast computation. In this respect, linear decoder are good candidates and have been widely used in motor BCIs. Yet, they have been very seldomly studied for speech reconstruction, and never for reconstruction of articulatory movements from intracranial activity. Here, we compared vanilla linear regression, ridge-regularized linear regressions, and partial least squares regressions for offline decoding of overt speech from cortical activity.MethodsTwo decoding paradigms were investigated: (1) direct decoding of acoustic vocoder features of speech, and (2) indirect decoding of vocoder features through an intermediate articulatory representation chained with a real-time-compatible DNN-based articulatory-to-acoustic synthesizer. Participant's articulatory trajectories were estimated from an electromagnetic-articulography dataset using dynamic time warping. The accuracy of the decoders was evaluated by computing correlations between original and reconstructed features.ResultsWe found that similar performance was achieved by all linear methods well above chance levels, albeit without reaching intelligibility. Direct and indirect methods achieved comparable performance, with an advantage for direct decoding.DiscussionFuture work will address the development of an improved neural speech decoder compatible with fast frame-by-frame speech reconstruction from ongoing activity at a millisecond timescale
: Seizure onset zone imaging
International audienceStereo-electroencephalography is used to localize the seizure onset zone and connected neuronal networks in surgical candidates suffering from intractable focal epilepsy. The concept of an epileptogenicity index has been proposed recently to represent the likelihood of various regions being part of the seizure onset zone. It quantifies low-voltage fast activity, the electrophysiological signature of seizure onset usually assessed visually by neurologists. Here, we revisit epileptogenicity in light of neuroimaging tools such as those provided in statistical parametric mapping software. Our goal is to propose a robust approach, allowing easy exploration of patients' brains in time and space. The procedure is based upon statistical parametric mapping, which is an established framework for comparing multi-dimensional image data that allows one to correct for inherent multiple comparisons. Statistics can also be performed at the group level, between seizures in the same patient or between patients suffering from the same type of epilepsy using normalization of brains to a common anatomic atlas. Results are obtained from three case studies (insular reflex epilepsy, cryptogenic frontal epilepsy and lesional occipital epilepsy) where tailored resection was performed, and from a group of 10 patients suffering from mesial temporal lobe epilepsy. They illustrate the basics of the technique and demonstrate its very good reproducibility and specificity. Most importantly, the proposed approach to the quantification of the seizure onset zone allows one to summarize complex signals in terms of a time-series of statistical parametric maps that can support clinical decisions. Quantitative neuroimaging of stereo-electroencephalographic features of seizures might thus help to provide better pre-surgical assessment of patients undergoing resective surgery
Simulation numérique d'un essai de soudage en rainure circulaire
Cet article présente la simulation numérique d'un essai de soudage en rainure circulaire effectué sur une maquette instrumentée. Ce test est utilisé par AREVA pour la caractérisation de la fissuration à chaud des matériaux d'apport lors d'un soudage par procédé TIG. Les calculs 2D élastoplastiques ont été validés grùce aux relevés de températures et de retraits de soudage. Les contraintes et déformations en tout point de la structure, à tout moment de l'opération de remplissage de la rainure, sont ainsi accessibles par la simulation
MOMAC: a SAXS/WAXS laboratory instrument dedicated to nanomaterials
International audienceThis article presents the technical characteristics of a newly built small-and wide-angle X-ray scattering (SAXS/WAXS) apparatus dedicated to structural characterization of a wide range of nanomaterials in the powder or dispersion form. The instrument is based on a high-flux rotating anode generator with a molybdenum target, enabling the assessment of highly absorbing samples containing heavy elements. The SAXS part is composed of a collimation system including a multilayer optic and scatterless slits, a motorized sample holder, a vacuum chamber, and a two-dimensional image-plate detector. All the control command is done through a TANGO interface. Normalization and data correction yield scattering patterns at the absolute scale automatically with a q range from 0.03 to 3.2 A Ë Ă1. The WAXS part features a multilayer collimating optic and a two-dimensional image-plate detector with variable sample-to-detector distances. The accessible q range is 0.4â9 A Ë Ă1 , ensuring a large overlap in q range between the two instruments. A few examples of applications are also presented, namely coupled SAXS/WAXS structure and symmetry determination of gold nanocrystals in solution and characterization of imogolite nanotubes and iron-filled carbon nanotube samples
Nonlinear magnetic induction by helical motion in a liquid sodium turbulent flow
International audienceWe report an experimental study of the magnetic field (B) over right arrow induced by a turbulent swirling flow of liquid sodium submitted to a transverse magnetic field (B) over right arrow (0). We show that the induced field can behave nonlinearly as a function of the magnetic Reynolds number, R-m. At low R-m, the induced mean field along the axis of the flow, , and the one parallel to (B) over right arrow (0), , first behave like R-m(2), whereas the third component, , is linear in R-m. The sign of is determined by the flow helicity. At higher R-m, (B) over right arrow strongly depends on the local geometry of the mean flow: decreases to zero in the core of the swirling flow but remains finite outside. We compare the experimental results with the computed magnetic induction due to the mean flow alone
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