Measuring uncertainty in human visual segmentation

Segmenting visual stimuli into distinct groups of features and visual objects is central to visual function. Classical psychophysical methods have helped uncover many rules of human perceptual segmentation, and recent progress in machine learning has produced successful algorithms. Yet, the computational logic of human segmentation remains unclear, partially because we lack well-controlled paradigms to measure perceptual segmentation maps and compare models quantitatively. Here we propose a new, integrated approach: given an image, we measure multiple pixel-based same--different judgments and perform model--based reconstruction of the underlying segmentation map. The reconstruction is robust to several experimental manipulations and captures the variability of individual participants. We demonstrate the validity of the approach on human segmentation of natural images and composite textures. We show that image uncertainty affects measured human variability, and it influences how participants weigh different visual features. Because any putative segmentation algorithm can be inserted to perform the reconstruction, our paradigm affords quantitative tests of theories of perception as well as new benchmarks for segmentation algorithms.Comment: 27 pages, 9 figures, 4 appendix, 3 figures in appendi

Stochastic models and dynamic measures for the characterization of bistable circuits

During the last few years, a great deal of interest has risen concerning the applications of stochastic methods to several biochemical and biological phenomena. Phenomena like gene expression, cellular memory, bet-hedging strategy in bacterial growth and many others, cannot be described by continuous stochastic models due to their intrinsic discreteness and randomness. In this thesis I have used the Chemical Master Equation (CME) technique to modelize some feedback cycles and analyzing their properties, including experimental data. In the first part of this work, the effect of stochastic stability is discussed on a toy model of the genetic switch that triggers the cellular division, which malfunctioning is known to be one of the hallmarks of cancer. The second system I have worked on is the so-called futile cycle, a closed cycle of two enzymatic reactions that adds and removes a chemical compound, called phosphate group, to a specific substrate. I have thus investigated how adding noise to the enzyme (that is usually in the order of few hundred molecules) modifies the probability of observing a specific number of phosphorylated substrate molecules, and confirmed theoretical predictions with numerical simulations. In the third part the results of the study of a chain of multiple phosphorylation-dephosphorylation cycles will be presented. We will discuss an approximation method for the exact solution in the bidimensional case and the relationship that this method has with the thermodynamic properties of the system, which is an open system far from equilibrium.In the last section the agreement between the theoretical prediction of the total protein quantity in a mouse cells population and the observed quantity will be shown, measured via fluorescence microscopy

Intégration du copolymères P(VDF-TrFE) à une nouvelle technologie de capteurs pyroélectriques (application à la détection d'empreintes digitales)

Depuis les années 2000, ATMEL fabrique des capteurs pyroélectriques pour la détection d'empreintes digitales. Le but de cette thèse est de faire évoluer la technologie actuelle vers une autre plus simple, moins coûteuse et plus robuste, et d'acquérir une maîtrise du matériau pyroélectrique et de ces performances. Notre travail a consisté, dans un premier temps, à comprendre en détail le comportement du P(VDF-TrFE) pyroélectrique, utilisé dans le capteur, à travers l'influence des traitements thermiques sur la morphologie des structures cristallines et sur le coefficient pyroélectrique. Les traitements thermique au-delà de la température de fusion se sont avérés les plus adaptés à l'obtention d'une phase cristalline ferroélectrique bêta stable et suffisamment cristallisée. Parallèlement, notre étude a démontré la possibilité d'améliorer légèrement l'activité pyroélectrique (d'environ 4 ou 5 C/m /K) uniquement en modifiant certains paramètres lors de l'application du champ électrique. Une étude sur la relation entre les paramètres de fabrication du copolymère, ces caractéristiques de mise en œuvre et ces performances pyroélectriques a permit de définir le matériau cible à approvisionner. Puis, nous nous sommes attachés à l'amélioration de l'adhérence du copolymère au sein de l'empilement technologique du capteur d'empreintes. Cette étape étant indispensable pour aboutir à l'élaboration d'une nouvelle structure. Deux solutions ont été retenues : l'une basée sur l'introduction d'un promoteur d'adhérence sous le copolymère et l'autre en substituant le copolymère lui-même par un mélange P(VDF-TrFE) /PMMA2%. Ce qui a permit de créer une nouvelle structure dont le nombre d'étape du procédé a été réduit de 5 à 3 briques technologiquesSince the 2000s, ATMEL manufactures pyroelectric sensor for the detection of fingerprints. The aim of this PhD is to change the current technology to another easier, less expensive and more robust, and to acquire a pyroelectric material and performance. Our work consisted, as a first step, to understand in detail the behavior of P (VDF-TrFE) pyroelectric used in the sensor, through the influence of heat treatment on the morphology of crystalline structures and the pyroelectric coefficient. Beyond the melting temperature, the thermal treatments was shown to be the most suitable to develop a bêta ferroelectric stable phase and sufficiently crystallized. Meanwhile, our study has demonstrated the ability to improve slightly the pyroelectric activity (about 4 or 5 C / m / K) only by modifying certain parameters when applying electric field. A study on the relationship between the production parameters of the copolymer and the pyroelectric performances helped us to define the target material. Then, we have improved the adhesion of the copolymer on the different substrates in the fingerprint sensor. This step is crucial for achieving the development of a new structure. Two solutions have been identified: one based on the introduction of an adhesion promoter under the copolymer and the other copolymer by substituting itself as a blend P(VDF-TrFE) / PMMA2%. As a consequence, we created a new structure in which the number of step of the process was reduced from five to three technological stepsMONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Intérêt de l'évaluation de la fonction vestibulaire dans l' implication cochléaire chez l ' enfant (sur une série de 79 patients)

Centre Technique Livre Ens. Sup. (774682301) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

GABA(B) receptors as potential therapeutic targets

gamma-Aminobutyric acid-B (GABA(B)) receptors are broadly expressed in the nervous system and have been implicated in a wide variety of neurological and psychiatric disorders. To date the only GABA(B) drug on the market is the agonist baclofen (Lioresal((R))) that is used to treat severe spasticity of cerebral and spinal origin. In addition baclofen is effective in animal models for many central and peripheral disorders, but side-effects and the development of tolerance prohibited a more widespread use of this drug in man. Similarly GABA(B) antagonists show great therapeutic promise but their shortcomings, e.g. the lack of brain penetration or some proconvulsive potential, prevented clinical development. The cloning of GABA(B) receptors in 1997 revived interest in these receptors as drug targets. The long-awaited availability of the tools that were necessary to develop more selective and safer drugs stimulated an impressive activity in the field. The demonstration that GABA(B) receptors needed to heteromerize for function provided new insights into the structure of G-protein coupled receptors in general and enabled to identify allosteric GABA(B) drugs. Gene knockout mice revealed neuronal systems that are under tonic GABA(B) control and therefore best suited for therapeutic intervention. Significant advances were made in clarifying the relationship between GABA(B) receptors and the receptors for gamma-hydroxybutyrate (GHB), a drug of abuse. Here we provide and update on the molecular composition, the physiology and the pharmacology of GABA(B) receptors and discuss to what extent our current knowledge influences ongoing and future drug discovery efforts

Régulation par les monoamines de l'expression de la vasopressine dans l'hypothalamus neuroendocrine (étude cytophysiologique chez la souris Tg8, knock-out pour la monoamine oxydase A (MAO-A))

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Que nous dit l’offre Airbnb sur l’évolution des territoires touristiques ? Le cas de La Rochelle/Île de Ré

International audienc

Anémie et cancer (quelles perspectives d'amélioration de la prise en charge du patient résistant à l'érythropoïétine ?)

PARIS-BIUP (751062107) / SudocSudocFranceF