1,527 research outputs found
A uniform Berry--Esseen theorem on -estimators for geometrically ergodic Markov chains
Let be a -geometrically ergodic Markov chain. Given some
real-valued functional , define
,
. Consider an estimator
, that is, a measurable function of the observations satisfying
with
some sequence of real numbers going to zero. Under some
standard regularity and moment assumptions, close to those of the i.i.d. case,
the estimator satisfies a Berry--Esseen theorem uniformly with
respect to the underlying probability distribution of the Markov chain.Comment: Published in at http://dx.doi.org/10.3150/10-BEJ347 the Bernoulli
(http://isi.cbs.nl/bernoulli/) by the International Statistical
Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm
Pattern formation by kicked solitons in the two-dimensionnal Ginzburg-Landau medium with a transverse grating
We consider the kick-induced mobility of two-dimensional (2D) fundamental
dissipative solitons in models of lasing media based on the 2D complex
Ginzburg-Landau (CGL) equation including a spatially periodic potential
(transverse grating). The depinning threshold is identified by means of
systematic simulations, and described by means of an analytical approximation,
depending on the orientation of the kick. Various pattern-formation scenarios
are found above the threshold. Most typically, the soliton, hopping between
potential cells, leaves arrayed patterns of different sizes in its wake. In the
laser cavity, this effect may be used as a mechanism for selective pattern
formation controlled by the tilt of the seed beam. Freely moving solitons
feature two distinct values of the established velocity. Elastic and inelastic
collisions between free solitons and pinned arrayed patterns are studied too.Comment: 15 pages, 20 figures (with 41 sub-figures
Vitesse de convergence en M-estimation de données markoviennes
International audienceLet be a -geometrically ergodic Markov chain with some fixed unbounded real-valued function and consider , \alpha\in\mathcalA\in \mathbbR for some real-valued functional . Define the estimator such that M_n(\widehat \alpha_n) \leq \min_{\alpha\in\mathcalA} M_n(\alpha) + c_n with , some sequence of real numbers decreasing to zero. Under some standard regularity assumptions, close to that of the i.i.d case, and under the moment assumption for some constants and , the estimator satisfies a Berry-Esseen theorem uniformly with respect to the underlying probability distribution of the Markov chain
High-frequency Near-field Physeter macrocephalus Monitoring by Stereo-Autoencoder and 3D Model of Sonar Organ
International audiencePassive acoustics allow us to study large animals and obtain information that could not be gathered through other methods. In this paper we study a set of near-field audiovisual recordings of a sperm whale pod, acquired with a ultra high-frequency and small aperture antenna. We propose a novel kind of autoencoder, a Stereo-Autoencoder, and show how it allows to build acoustic manifolds in order to increase our knowledge regarding the characterization of their vocalizations, and possible acoustic individual signature
Les mots du vin : experts et novices diffÚrent-ils quand ils décrivent des vins ?
Un expert en vin perçoit-il et dĂ©crit-il lâodeur dâun vin de façon plus analytique quâun novice ? Pour rĂ©pondre Ă cette question, nous avons demandĂ© Ă un groupe dâexperts et un groupe de novices de dĂ©crire des vins Ă lâaide dâune liste de termes organisĂ©e en trois niveaux de catĂ©gorisation allant du plus gĂ©nĂ©ral au plus spĂ©cifique. Nous avons ensuite demandĂ© aux mĂȘmes sujets dâapparier les descriptions rĂ©alisĂ©es par une autre personne avec les vins correspondants. Les rĂ©sultats montrent que les descriptions effectuĂ©es par les experts sont plus prĂ©cises et conduisent Ă de meilleures performances dâappariement que celles effectuĂ©es par les novices. De plus, la distance entre les descriptions dâexperts et celles de novices augmente avec le niveau de prĂ©cision des termes.The words of wineDo wine experts perceive and describe wines more analytically than novices ? To answer this question we asked a group of wine experts and a group of novices to describe wines with a list of terms organized hierarchically in three levels (from general to specific). Then we asked the same subjects to find the wine described by other subjects. We found that experts are more precise in their description and that it is easier for subjects to identify a wine described by an expert than to identify a wine described by a novice. We also found that experts and novices differ most when they use specific terms
Les mots du vin : experts et novices diffÚrent-ils quand ils décrivent des vins ?
Un expert en vin perçoit-il et dĂ©crit-il lâodeur dâun vin de façon plus analytique quâun novice ? Pour rĂ©pondre Ă cette question, nous avons demandĂ© Ă un groupe dâexperts et un groupe de novices de dĂ©crire des vins Ă lâaide dâune liste de termes organisĂ©e en trois niveaux de catĂ©gorisation allant du plus gĂ©nĂ©ral au plus spĂ©cifique. Nous avons ensuite demandĂ© aux mĂȘmes sujets dâapparier les descriptions rĂ©alisĂ©es par une autre personne avec les vins correspondants. Les rĂ©sultats montrent que les descriptions effectuĂ©es par les experts sont plus prĂ©cises et conduisent Ă de meilleures performances dâappariement que celles effectuĂ©es par les novices. De plus, la distance entre les descriptions dâexperts et celles de novices augmente avec le niveau de prĂ©cision des termes.The words of wineDo wine experts perceive and describe wines more analytically than novices ? To answer this question we asked a group of wine experts and a group of novices to describe wines with a list of terms organized hierarchically in three levels (from general to specific). Then we asked the same subjects to find the wine described by other subjects. We found that experts are more precise in their description and that it is easier for subjects to identify a wine described by an expert than to identify a wine described by a novice. We also found that experts and novices differ most when they use specific terms
Revisiting the relation between language and cognition:A Cross-cultural Study with odors
Nous avons Ă©tudiĂ© la relation entre la codabilitĂ© des odeurs et leur reprĂ©sentation en mĂ©moire dans trois groupes culturels, français, amĂ©ricain et vietnamien. Dans une premiĂšre expĂ©rience, nous avons demandĂ© Ă des participants des trois cultures dâidentifier par deux fois un ensemble de 40 odorants. A partir de cette tĂąche, nous avons calculĂ© la codabilitĂ© de chacun des 40 odorants. Dans une deuxiĂšme expĂ©rience, nous avons demandĂ© Ă un autre groupe de participants de chaque culture de rĂ©aliser une tĂąche de reconnaissance par oui/non sur le mĂȘme ensemble dâodorants. Les rĂ©sultats de lâexpĂ©rience 1 suggĂšrent que la codabilitĂ© des odeurs (1) est une dimension pertinente car certaines odeurs sont plus codables que dâautres au sein dâune mĂȘme culture, (2) peut ĂȘtre mesurĂ©e de maniĂšre Ă©quivalente par des indices dâaccords intra et interpersonnels, et (3) varie entre les cultures en fonction de lâenvironnement olfactif et de la structure du langage. Les rĂ©sultats de lâexpĂ©rience 2 montrent que les scores de codabilitĂ© en France prĂ©disent les performances de mĂ©moire de reconnaissance dans les trois cultures mais que les scores aux Etats-Unis et au Vietnam nâen prĂ©disent aucun des scores de reconnaissances.We investigated the relationship between odor codability and odor memory representation in three cultural groups: French, American, and Vietnamese. In a first experiment, we asked participants from the three cultures to identify twice a set of 40 common odorants. From this task, we computed the codability of each of the 40 odorants. In a second experiment, we asked another group of participants from each culture to perform a yes/no recognition task on the same set of odorants. Results from Experiment 1 suggest that odor codability (1) is a meaningful dimension because some odors are more codable than others within a culture, (2) is equivalently measurable by several inter- and intrapersonal agreement indices, and (3) varies between cultures as a function of both the olfactory environment and language structure. Results from Experiment 2 show that the French codability scores predict recognition memory performance in all three cultures but that the American and Vietnamese codability scores predict none of the recognition performances
Planar Optical Nanoantennas Resolve Cholesterol-Dependent Nanoscale Heterogeneities in the Plasma Membrane of Living Cells
Optical nanoantennas can efficiently confine light into nanoscopic hotspots, enabling single-molecule detection sensitivity at biological relevant conditions. This innovative approach to breach the diffraction limit offers a versatile platform to investigate the dynamics of individual biomolecules in living cell membranes and their partitioning into cholesterol-dependent lipid nanodomains. Here, we present optical nanoantenna arrays with accessible surface hotspots to study the characteristic diffusion dynamics of phosphoethanolamine (PE) and sphingomyelin (SM) in the plasma membrane of living cells at the nanoscale. Fluorescence burst analysis and fluorescence correlation spectroscopy performed on nanoantennas of different gap sizes show that, unlike PE, SM is transiently trapped in cholesterol-enriched nanodomains of 10 nm diameter with short characteristic times around 100 ÎŒs. The removal of cholesterol led to the free diffusion of SM, consistent with the dispersion of nanodomains. Our results are consistent with the existence of highly transient and fluctuating nanoscale assemblies enriched by cholesterol and sphingolipids in living cell membranes, also known as lipid rafts. Quantitative data on sphingolipids partitioning into lipid rafts is crucial to understand the spatiotemporal heterogeneous organization of transient molecular complexes on the membrane of living cells at the nanoscale. The proposed technique is fully biocompatible and thus provides various opportunities for biophysics and live cell research to reveal details that remain hidden in confocal diffraction-limited measurements.Peer ReviewedPostprint (author's final draft
Pratique de la prophylaxie de la maladie thromboembolique veineuse: enquĂȘte rĂ©alisĂ©e auprĂšs des professionnels de santĂ© de la ville de Ouagadougou
Introduction: l'impact clinique et l'incidence de la maladie thromboembolique veineuse ont conduit à établir des recommandations pour la thromboprophylaxie.L'objectif de notre étude était d'évaluer la pratique de cette prophylaxie par les professionnels de santé de Ouagadougou.
MĂ©thodes: il s'est agi d'une enquĂȘte d'intention rĂ©alisĂ©e dans le mois de mai 2012 au Centre Hospitalier Universitaire Yalgado OuĂ©draogo et Centre MĂ©dical avec Antenne chirurgicale Paul VI. Un questionnaire a Ă©tĂ© administrĂ© auprĂšs des prescripteurs impliquĂ©s dans la prophylaxie de la maladie thromboembolique veineuse (MTEV).
Résultats: une interview a été administrée à 86 professionnels de santé dont 20 attachés de santé en anesthésie-réanimation, 17 chirurgiens, 11 médecins généralistes et 07 gynécologue-obstétriciens. Leur expérience professionnelle était inférieure à cinq ans dans 65% des cas et ils exerçaient dans 70% des cas au CHU-YO. Les héparines de bas poids moléculaire étaient les plus utilisées (81,4%) avec une intention de prescription significativement plus élevée en réanimation et en chirurgie (p<0,05). Dans 65,7% des cas, la prophylaxie était maintenue jusqu'à la mobilisation des patients. Le coût élevé de l'héparinothérapie représentait une raison de la non utilisation de la prophylaxie dans 46,5% des cas.
Conclusion: nous constatons que la réalisation de la prophylaxie de la MTEV reste insuffisante à Ouagadougou en dépit de l'existence de recommandations précises de bonnes pratiques. Ces résultats suggÚrent la nécessité de la formation médicale continue des professionnels de santé, avec l'établissement des recommandations de pratique clinique adaptée à notre niveau de développement
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