Markov games with frequent actions and incomplete information

We study a two-player, zero-sum, stochastic game with incomplete information on one side in which the players are allowed to play more and more frequently. The informed player observes the realization of a Markov chain on which the payoffs depend, while the non-informed player only observes his opponent's actions. We show the existence of a limit value as the time span between two consecutive stages vanishes; this value is characterized through an auxiliary optimization problem and as the solution of an Hamilton-Jacobi equation

Photolithographic processing of silver loaded dielectric coatings based on preformed colloidal TiO2nanoparticles dispersed in a mesoporous silica binder

Titanium dioxide is a well known photocatalyst for reactions involving surface trapped photogenerated carriers. Noble metal photo-reduction may be used for the processing of silver/TiO 2 nanocomposite coatings that may exhibit interesting optical and electrical properties. We present here results of our investigations performed on an original system consisting of preformed colloidal TiO 2 nanoparticles homogeneously dispersed within a mesoporous silica host matrix. Light irradiation of samples immerged in an aqueous silver salt solution leads to the homogeneous deposition of silver islands in the vicinity of the TiO 2 particles and throughout the film thickness. The silver volume fraction is directly controlled by the irradiation dose up to a value of about 16 vol.%. Films exhibit tunable plasmonic properties that correspond to silver nanoparticles in interaction, and a percolation threshold is observed at 8–10 vol.%, leading to films with a conductivity of about 40 S cm −1 . The major interest of this method lies in the high silver reduction quantum efficiency (about 50%) and the possibility to modulate optical and electronic properties by light irradiation while the low temperature of processing permits the photolithographic deposition of metallic patterns on organic flexible substrates

Représentations sociales, pratiques sociales et travail émotionnel : analyse psychosociale de la sédation en contexte de prise en charge en soins palliatifs

Journée en visioconférencejournée doctorale organisée par la Plateforme Nationale pour la recherche sur la fin de vie. 7 doctorants ont présenté leurs thèse

Markov games with frequent actions and incomplete information — The Limit Case

We study the asymptotics of a class of two-player, zero-sum stochastic game with incomplete information on one side whenthe time span between two consecutive stages vanishes. The informed player observes the realization of a Markov chain onwhich the payoffs depend, whereas the noninformed player only observes his opponent’s actions. We show the existence ofa limit value; this value is characterized through an auxiliary optimization problem and as the solution of a Hamilton-Jacobiequation.nonnonouirechercheInternationa

Observer la sédation : « fragments » issus d'une analyse psycho-sociale

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Calibration of an adaptive microscope using phase diversity

International audienceAccurate control over the phase and amplitude modulation in an adaptive microscope is essential to the quality of aberration correction that can be achieved. In this paper we present a robust and compact method for characterising such amplitude and phase modulation in the pupil plane of the focussing objective. This method, based on phase diversity, permits calibrating the microscope as a whole and thus avoids errors in the alignment of the wavefront shaping device after calibration and the resulting imprecision in the induced modulation: by acquiring three 2D images of the point spread function at different distances from the focal plane, we show that the electric field distribution at the pupil plane can be retrieved using an iterative algorithm. We have applied this technique to the characterisation of the phase modulation induced by a deformable mirror when conjugated with the entrance pupil of different objectives, which permits accurate evaluation of the performance of the mirror for subsequent aberration correction. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE)

Are we performing episiotomies correctly? A study to evaluate French technique in a high-risk maternity unit

International audienceINTRODUCTION:The aim of this study was to evaluate episiotomy technique, in particular suture angles, and any correlation between suture angle and severe perineal tears.MATERIAL AND METHODS:An observational questionnaire-based study was conducted between 01 August 2015 and 30 April 2016 among accoucheurs performing episiotomies in a French maternity unit with facilities for high-risk pregnancies. For each patient included, accoucheurs were asked to measure the episiotomy suture angle, and to record the angle at which they thought they had cut, the length of the episiotomy, its distance from the anus, and whether the woman sustained a sphincter injury.RESULTS:The centre's episiotomy rate during the study period was 15%. We analyzed the characteristics of episiotomies performed on 89 women (68 by doctors and 21 by midwives). Only 43% of suture angles were between 45° and 60° (45.6% of those performed by doctors vs 38.1% by midwives, p=0.8623), whereas 91% of accoucheurs thought they had cut within the correct range. Doctors made longer incisions than midwives (4 [4.2-5.0] vs 3 [2.5-3.5] cm, p=0.0006). Only 40.5% of accoucheurs correctly estimated the incision angle. Twelve (13.64%) of the 88 women sustained a third-degree perineal tear. The risk of sphincter injury was higher with suture angles <45° (odds ratio 5.46 [1.11-26.75], p=0.037). After multivariate analysis, this result was no longer significant (p=0.079).CONCLUSION:It appears that many accoucheurs have difficulty estimating episiotomy incision angles correctly and that education and training in this domain requires improvement