A cognitive prosthesis for complex decision-making

While simple heuristics can be ecologically rational and effective in naturalistic decision making contexts, complex situations require analytical decision making strategies, hypothesis-testing and learning. Sub-optimal decision strategies – using simplified as opposed to analytic decision rules – have been reported in domains such as healthcare, military operational planning, and government policy making. We investigate the potential of a computational toolkit called “IMAGE” to improve decision-making by developing structural knowledge and increasing understanding of complex situations. IMAGE is tested within the context of a complex military convoy management task through (a) interactive simulations, and (b) visualization and knowledge representation capabilities. We assess the usefulness of two versions of IMAGE (desktop and immersive) compared to a baseline. Results suggest that the prosthesis helped analysts in making better decisions, but failed to increase their structural knowledge about the situation once the cognitive prosthesis is removed

Développement de nanoparticules luminescentes à base d'or et d'argent pour l'imagerie cellulaire

Les nanoparticules (nanoPs) sont de plus en plus utilisées afin de surmonter les différentes limitations des sondes luminescentes moléculaires, en particulier en incorporant différents colorants organiques dans des nanoPs de silice. Ces nanoPs dopées au colorant offrent plusieurs avantages, incluant une sensitivité de détection optique plus élevée, une plus grande photostabilité et une toxicité plus basse. Afin d'augmenter les propriétés luminescentes de ces nanoPs hautement fluorescentes, le phénomène du Metal-Enhanced Fluorescence (MEF) a été exploité, notamment en introduisant un coeur métallique sphérique dans la matrice de silice contenant le colorant. Ce phénomène est basé sur les interactions du fluorophore avec les électrons libres du métal responsables de l'absorption du plasmon, qui en retour augmente le champ électrique local et modifie les taux d'excitation et d'émission du colorant. Dans le cadre du projet, nous avons développé des nanoPs d'or sphériques luminescentes pour leur comportement stable en milieu biologique et nous avons développé des nanoPs non-sphériques, plus précisément des nanoPs cubiques luminescentes en argent afin de déterminer l'effet d'une géométrie différente sur l'effet MEF. Nous avons mis au point des particules de type coeur/coquille dans lesquelles nous avons incorporé un colorant dans différentes épaisseurs de silice déposées sur le coeur métallique. Plusieurs outils de microscopie et de spectroscopie ont été utilisés afin d'évaluer les performances des nanoPs métalliques sur l'émission du fluorophore

Fabrication et étude de verres et de fibres optiques basés sur le système AgI-AgPO3-WO3 pour des applications en électrophysiologie

Tableau d'honneur de la Faculté des études supérieures et postdorales, 2016-2017L’utilisation de fibres multifonctionnelles pour le transport simultané de la lumière et du courant électrique est une alternative de plus en plus attrayante dans le domaine de l’optogénétique en électrophysiologie où l’excitation lumineuse des cellules nerveuses permet de générer un signal électrique qui peut être enregistré. Ce transport simultané offre l’avantage de pouvoir s’affranchir de la «patch-clamp» pour l’enregistrement électrique, rendant ainsi la méthode plus pratique. La majorité des fibres multifonctionnelles développées dans ce domaine ont de larges diamètres, ce qui ne permet pas de sonder de petits groupes de cellules ou des cellules uniques dont la taille avoisine 10 μm. À cet égard, utiliser une fibre optique avec une géométrie de type «taper» représente une voie prometteuse pour surmonter cette limitation (Fig 1.1). En effet, le cœur optique de l’extrémité d’une fibre «taper» se distingue par son petit diamètre de l’ordre de 10 μm par rapport au reste de la fibre dont le diamètre peut être de 20 à 60 fois plus large afin de faciliter la connexion à la source lumineuse. Dans cette thèse, nous avons développé des verres et des fibres optiques conduisant l’électricité basés sur le système vitreux AgI-AgPO3-WO3. Un large domaine vitreux a été mis en évidence, permettant la préparation de plusieurs verres de compositions différentes. Dans ce système vitreux, le transport du courant est assuré par les ions d’argent via un mécanisme de conduction ionique qui varie en fonction de la température. Par ailleurs, le verre offre une fenêtre de transmission dans le visible et le proche infrarouge dont la largeur est fortement influencée par l’interaction entre l’AgI et l’oxyde de tungstène WO3. En outre, le WO3 permet d’augmenter la durabilité chimique du verre. Ces verres peuvent être transformés aisément en fibre optique présentant des conductivités de l’ordre 10-1 S·cm-1 à température ambiante et à basses fréquences (1 Hz - 10 kHz). Ces fibres offrent une bonne transmission dans le proche infrarouge, mais faible dans le bleu qui est la lumière la plus utilisée en optogénétique. Aussi, des fibres composites à base de polymères avec différentes configurations géométriques ont été développées afin de permettre la transmission de la lumière bleue grâce au couple polycarbonnate/polymethacrylate de méthyl et la conduction électrique grâce au verre AgI-AgPO3-WO3. Enfin, des fibres composites de type «taper» ont été produites et caractérisées pour des applications dans le domaine de l’optogénétique en électrophysiologie.The use of multifunctional fibers for simultaneous light guiding and electrical transport is an increasingly attractive alternative in the field of optogenetic in electrophysiology where light excitation of nerve cells generates an electrical signal that can be recorded. This simultaneous transport offers the advantage to get rid of the patch-clamp for electrical recording, making the method more practical. The majority of multifunctional fibers developed in this area have large diameters, which does not allow the probing of small group of cells or single cell whose size is around 10 μm. In this regard, using an optical fiber with a taper tipped geometry represents a powerful approach to overcome this limitation (Figure 1.1). The optical core of a taper fiber end is characterized by its small diameter of the order of 10 μm relative to the rest of the fiber whose diameter can be 20 to 60 times larger to facilitate the connection with the light source. In this thesis, we have developed glasses and optical fibers that conduct electricity based on the AgI-AgPO3-WO3 glass system. A large glass domain has been demonstrated, enabling the fabrication of several glasses of different compositions. In this glass system, the electrical transport is ensured by the silver ions via an ionic conduction mechanism that varies with temperature. Moreover, the glass has a transmission window in the visible and the near infrared which is strongly influenced by the interaction between the AgI and tungsten oxide WO3. In addition, the WO3 can increase the chemical durability of the glass. These glasses can be easily stretched in optical fiber with electrical conductivity in the order of 10-1 S· cm-1 at room temperature and low frequencies. These fibers offer high transmission in the near infrared, but low transmission in the blue which is the most used light in optogenetics. To overcome this issue, composite fibers based on polymers with different geometric configurations were developed. The transmission of the blue light is provided by the polycarbonnate/polymethylmethacrylate duo and the electric transport by the AgI-AgPO3-WO3 glass. Finally, the composite fibers were transformed into taper tipped fibers and were characterized for applications the field of optogenetics

Assessing the Electrochemical Stability Window of NASICON-Type Solid Electrolytes

All-Solid-State Lithium Batteries (ASSLBs) are promising since they may enable the use of high potential materials as positive electrode and lithium metal as negative electrode. This is only possible through solid electrolytes (SEs) stated large electrochemical stability window (ESW). Nevertheless, reported values for these ESWs are very divergent in the literature. Establishing a robust procedure to accurately determine SEs’ ESWs has therefore become crucial. Our work focuses on bringing together theoretical results and an original experimental set up to assess the electrochemical stability window of the two NASICON-type SEs Li1.3Al0.3Ti1.7(PO4)3 (LATP) and Li1.5Al0.5Ge1.5(PO4)3 (LAGP). Using first principles, we computed thermodynamic ESWs for LATP and LAGP and their decomposition products upon redox potentials. The experimental set-up consists of a sintered stack of a thin SE layer and a SE-Au composite electrode to allow a large contact surface between SE and conductive gold particles, which maximizes the redox currents. Using Potentiostatic Intermittent Titration Technique (PITT) measurements, we were able to accurately determine the ESW of LATP and LAGP solid electrolytes. They are found to be [2.65–4.6 V] and [1.85–4.9 V] for LATP and LAGP respectively. Finally, we attempted to characterize the decomposition products of both materials upon oxidation. The use of an O2 sensor coupled to the electrochemical setup enabled us to observe operando the production of O2 upon LAGP and LATP oxidations, in agreement with first-principles calculations. Transmission Electron Microscopy (TEM) allowed to observe the presence of an amorphous phase at the interface between the gold particles and LAGP after oxidation. Electrochemical Impedance Spectroscopy (EIS) measurements confirmed that the resulting phase increased the total resistance of LAGP. This work aims at providing a method for an accurate determination of ESWs, considered a key parameter to a successful material selection for ASSLBs. © Copyrigh

Frequency tunable continuous THz wave generation in a periodically poled fiber

An all-fiber approach to terahertz generation using a periodically poled optical fiber is proposed and experimentally demonstrated. In the proposed approach, a continuous-wave THz wave is generated at a periodically poled fiber by beating two optical wavelengths from two laser sources with the wavelength spacing corresponding to the frequency of the THz wave. The key component in the system is the periodically poled fiber, which is made by a twin-hole fiber with the fiber core residing between two holes. The twin-hole fiber is then thermally poled at a temperature of similar to 260 degrees C with a voltage of 3.3 kV applied to the silver electrodes inside the two holes to introduce second-order nonlinearity. The quasi phase matching (QPM) condition is achieved by periodically erasing the thermal poling induced second-order nonlinearity with an ultraviolet laser, which enhances the energy conversion efficiency. The proposed approach is validated by an experiment. The emission of a THz wave centered at 3.8 THz with an output power of 0.5 mu W is observed. The frequency tunability between 2.2 and 3.8 THz is also experimentally demonstrated

Noise Annoyance from Industrial and Road Traffic Combined Noises: A Survey and a Total Annoyance Model Comparison

International audienceThe literature on noise annoyance emphasizes that acoustical factors cannot totally explain the annoyance felt by a population exposed to community noises, and that some non-acoustical factors have an effect on annoyance. This research paper deals with the annoyance caused by combined noises coming from road traffic and an industrial site. This type of combination has been very little studied to date. An . in situ study was conducted in an area of a French town exposed to these two noise sources. To investigate the annoyance caused by these combined noises, the work involved both a mapping of the industrial and road traffic noises present in the survey area and a questionnaire designed to evaluate the noise annoyance experienced by residents and to identify the factors that probably influence noise annoyance. The results highlight the link between the noise levels measured and the annoyance felt by the respondents. They also show that certain non-acoustical factors have an impact on annoyance felt. Indeed, the results highlight a positive correlation between fear of industrial sites and the annoyance expressed. They also show correlations between some items to evaluate noise sensitivity and the annoyance expressed. No significant correlation has been found between annoyance and the other non-acoustical factors such as age, sex and length of residence. Finally, several total annoyance models were tested for this noise combination. Two of them, namely the strongest component model and a proposed perceptual version of the mixed model, were able to better predict total annoyance than the other tested models

A Wireless Multi-Sensor Dielectric Impedance Spectroscopy Platform

This paper describes the development of a low-cost, miniaturized, multiplexed, and connected platform for dielectric impedance spectroscopy (DIS), designed for in situ measurements and adapted to wireless network architectures. The platform has been tested and used as a DIS sensor node on ZigBee mesh and was able to interface up to three DIS sensors at the same time and relay the information through the network for data analysis and storage. The system is built from low-cost commercial microelectronics components, performs dielectric spectroscopy ranging from 5 kHz to 100 kHz, and benefits from an on-the-fly calibration system that makes sensor calibration easy. The paper describes the microelectronics design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the testing of the platform for in situ dielectric impedance spectroscopy applications pertaining to fertilizer sensing, water quality sensing, and touch sensing

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