This study compares, for listeners with normal hearing and listeners with hearing loss, the recognition performances obtained with digit-pair and digit-triplet stimulus sets presented in multitalker babble. Digits 1 through 10 (excluding 7) were mixed in approximately 1,000 ms segments of babble from 4 to -20 dB signal-to-babble (S/B) ratios, concatenated to form the pairs and triplets, and recorded on compact disc. Nine and eight digits were presented at each level for the digit-triplet and digit-pair paradigms, respectively. For the listeners with normal hearing and the listeners with hearing loss, the recognition performances were 3 dB and 1.2 dB better, respectively, on digit pairs than on digit triplets. For equal intelligibility, the listeners with hearing loss required an approximately 10 dB more favorable S/B than the listeners with normal hearing. The distributions of the 50% points for the two groups had no overlap.

A space camera is a promising candidate to address the non-stop rising interest for astrophysics research in the Compton regime. The MeVCube mission is intended to be launched in 2022, hosting an on-board Compton Camera. To better support the development of the instrument in this early stage, a series of feasibility studies to assess two potential launch orbits were performed. The studies were composed by a series of mission analysis simulations which permitted the characterisation of the orbital environments for the two orbital options. Several sources of background noise to the instrument were identified. The population of trapped protons and trapped electrons were simulated for the periods of Solar Minimum and Solar Maximum, as well as the levels of Galactic Cosmic Ray (GCR) flux. The performance of trade-off studies concluded that an equatorial orbit is more preferable for reducing the influence of background noise. To better estimate the environment effects at the equatorial orbit, the number of particles which can penetrate the detector shielding were simulated. The next step was to perform a series secondary studies whose aim were to simulate the induced current on the electrodes, produced by the interactions occurring within the detector. The actualisation of these simulations required the study of photon interaction with matter, the various Cadmium-Zink-Telluride (CZT) types and the how they operate, and the use of a sophisticated software to perform the appropriate simulations. COMSOL, which allows the method of FEA, was chosen as the tool to perform the simulations. The geometry of the detector voxel was primarily designed in SIEMENS NX. The geometry was inserted into COMSOL, where a number of iterations were performed to finalise the appropriate mesh size, which ensured an accurate representation of the Electric field and the Weighting potential within the detector voxel. The induced current on the electrodes was decided to be calculated via MATLAB. As a verification step it was thought useful to firstly plot the weighting potential of the three electrodes under test; the chosen anode pixel, the steering grid and the cathode. The process revealed a series of numerical errors, most likely introduced by the type of mesh chosen or by the data manipulation process via MATLAB. Significant reduction of the numerical errors would lead to more accurate values for the induced current. Unfortunately, due to time constraints this was a task that was not completed. Solving this problem would be optimal for future studies with MATLAB, as the induced current on the electrodes can be correctly calculated based on charge transport within the detector bulk. / MeVCube, DESY

La matière sombre est un mystère dans le domaine de l’astrophysique depuis déjà plusieurs années. De nombreuses observations montrent que jusqu’à 85 % de la masse gravitationnelle totale de l’univers serait composée de cette matière de nature inconnue. Une théorie expliquant cette masse manquante considérerait les WIMPs (Weakly Interacting Massive Particles), particules stables, non chargées, prédites par des extensions du modèle standard, comme candidats. Le projet PICASSO (Projet d’Identification des CAndidats Supersymétriques à la matière Sombre) est une expérience qui tente de détecter directement le WIMP. Le projet utilise des détecteurs à gouttelettes de fréon (C4F10) surchauffées. La collision entre un WIMP et le noyau de fluor crée un recul nucléaire qui cause à son tour une transition de phase de la gouttelette liquide à une bulle gazeuse. Le bruit de ce phénomène est alors capté par des senseurs piézoélectriques montés sur les parois des détecteurs. Le WIMP n’est cependant pas la seule particule pouvant causer une telle transition de phase. D’autres particules environnantes peuvent former des bulles, telles les particules alpha où même des rayons gamma . Le système d’acquisition de données (DAQ) est aussi en proie à du bruit électronique qui peut être enregistré, ainsi que sensible à du bruit acoustique extérieur au détecteur. Finalement, des fractures dans le polymère qui tient les gouttelettes en place peut également causer des transitions de phase spontanées. Il faut donc minimiser l’impact de tous ces différents bruit de fond. La pureté du matériel utilisé dans la fabrication des détecteurs devient alors très importante. On fait aussi appel à des méthodes qui impliquent l’utilisation de variables de discrimination développées dans le but d’améliorer les limites d’exclusion de détection du WIMP. / Dark matter has been a mystery for astrophysicists for years now. Numerous observations have shown that up to 85 % of the gravitation mass of the universe is made of this unknown type of matter. One of the theories explaining this missing mass problem considers WIMPs (Weakly Interacting Massive Particles), neutral stable particles predicted by extensions of the standard model, as possible candidates. The PICASSO experiment (Project In Canada to Search for Supersymetric Objects) tries to detect this particle directly. The technique uses superheated droplet detectors, with freon (C4F10) as the active medium. When a WIMP hits the fluorine nucleus, it creates a nuclear recoil, which in turn triggers a phase transition from a liquid droplet to a gaseous bubble. The acoustic noise of this event is then recorded by piezoelectric transducers mounted on the walls of the detector. There are however other particles than the WIMPs that can trigger this phase transition. Alpha particles, or even gamma rays can create bubbles. The Data Acquisition System (DAQ) is also subject to electronic noise that can be picked up, and to acoustic noise coming from an exterior source. Fractures in the polymer holding the droplets in place can also trigger spontaneous phase transitions. There is therefore a need to minimize the impact of these background noises. The level of purity of the ingredients used in detector fabrication then becomes very important. Digital processing methods are also used to develop discrimination variables that improve the limits of detection of the WIMP.

Suite à un état de l'art détaillant la création et l'utilisation de l'espace sonore dans divers environnements urbains virtuels (soundmaps, jeux vidéo, réalité augmentée), il s'agira de déterminer une méthodologie et des techniques de conception pour les espaces sonores urbains virtuels du point de vue de l'immersion, de l'interface et de la dramaturgie.ces développements se feront dans le cadre du projet terra dynamica, tendant vers une utilisation plurielle de la ville virtuelle (sécurité et sureté, transports de surface, aménagement de l'urbanisme, services de proximité et citoyens, jeux). le principal objectif du doctorat sera de déterminer des réponses informatiques concrètes à la problématique suivante : comment, en fonction de leur utilisation anticipée, les espaces sonores urbains virtuels doivent-ils être structurés et avec quels contenus?la formalisation informatique des solutions étayées au fil du doctorat et la création du contenu sonore illustrant le projet seront basés sur l'analyse de données scientifiques provenant de domaines variés tels que la psychologie de la perception, l'architecture et l'urbanisme, l'acoustique, la recherche esthétique (musicale) ainsi que sur l'observation et le recueil de données audio-visuelles du territoire urbain, de manière à rendre compte tant de la richesse du concept d'espace sonore que de la multiplicité de ses déclinaisons dans le cadre de la ville virtuelle. / In video gaming and interactive media, the making of complex sound ambiences relies heavily on the allowed memory and computational resources. So a compromise solution is necessary regarding the choice of audio material and its treatment in order to reach immersive and credible real-time ambiences. Alternatively, the use of procedural audio techniques, i.e. the generation of audio content relatively to the data provided by the virtual scene, has increased in recent years. Procedural methodologies seem appropriate to sonify complex environments such as virtual cities.In this thesis we specifically focus on the creation of interactive urban sound ambiences. Our analysis of these ambiences is based on the Soundscape theory and on a state of art on game oriented urban interactive applications. We infer that the virtual urban soundscape is made of several perceptive auditory grounds including a background. As a first contribution we define the morphological and narrative properties of such a background. We then consider the urban background sound as a texture and propose, as a second contribution, to pinpoint, specify and prototype a granular synthesis tool dedicated to interactive urban sound backgrounds.The synthesizer prototype is created using the visual programming language Pure Data. On the basis of our state of the art, we include an urban ambiences recording methodology to feed the granular synthesis. Finally, two validation steps regarding the prototype are described: the integration to the virtual city simulation Terra Dynamica on the one side and a perceptive listening comparison test on the other.

La matière sombre est un mystère dans le domaine de l’astrophysique depuis déjà plusieurs années. De nombreuses observations montrent que jusqu’à 85 % de la masse gravitationnelle totale de l’univers serait composée de cette matière de nature inconnue. Une théorie expliquant cette masse manquante considérerait les WIMPs (Weakly Interacting Massive Particles), particules stables, non chargées, prédites par des extensions du modèle standard, comme candidats. Le projet PICASSO (Projet d’Identification des CAndidats Supersymétriques à la matière Sombre) est une expérience qui tente de détecter directement le WIMP. Le projet utilise des détecteurs à gouttelettes de fréon (C4F10) surchauffées. La collision entre un WIMP et le noyau de fluor crée un recul nucléaire qui cause à son tour une transition de phase de la gouttelette liquide à une bulle gazeuse. Le bruit de ce phénomène est alors capté par des senseurs piézoélectriques montés sur les parois des détecteurs. Le WIMP n’est cependant pas la seule particule pouvant causer une telle transition de phase. D’autres particules environnantes peuvent former des bulles, telles les particules alpha où même des rayons gamma . Le système d’acquisition de données (DAQ) est aussi en proie à du bruit électronique qui peut être enregistré, ainsi que sensible à du bruit acoustique extérieur au détecteur. Finalement, des fractures dans le polymère qui tient les gouttelettes en place peut également causer des transitions de phase spontanées. Il faut donc minimiser l’impact de tous ces différents bruit de fond. La pureté du matériel utilisé dans la fabrication des détecteurs devient alors très importante. On fait aussi appel à des méthodes qui impliquent l’utilisation de variables de discrimination développées dans le but d’améliorer les limites d’exclusion de détection du WIMP. / Dark matter has been a mystery for astrophysicists for years now. Numerous observations have shown that up to 85 % of the gravitation mass of the universe is made of this unknown type of matter. One of the theories explaining this missing mass problem considers WIMPs (Weakly Interacting Massive Particles), neutral stable particles predicted by extensions of the standard model, as possible candidates. The PICASSO experiment (Project In Canada to Search for Supersymetric Objects) tries to detect this particle directly. The technique uses superheated droplet detectors, with freon (C4F10) as the active medium. When a WIMP hits the fluorine nucleus, it creates a nuclear recoil, which in turn triggers a phase transition from a liquid droplet to a gaseous bubble. The acoustic noise of this event is then recorded by piezoelectric transducers mounted on the walls of the detector. There are however other particles than the WIMPs that can trigger this phase transition. Alpha particles, or even gamma rays can create bubbles. The Data Acquisition System (DAQ) is also subject to electronic noise that can be picked up, and to acoustic noise coming from an exterior source. Fractures in the polymer holding the droplets in place can also trigger spontaneous phase transitions. There is therefore a need to minimize the impact of these background noises. The level of purity of the ingredients used in detector fabrication then becomes very important. Digital processing methods are also used to develop discrimination variables that improve the limits of detection of the WIMP.

Dans le cadre des activités de maintenance des centrales nucléaires, les personnes intervenant sur des chantiers en zone contrôlée doivent effectuer des mesures de contamination surfacique sur leurs outils, gants, sur tenue de travail et sur les parties de leur corps susceptible d’être contaminées (cou et tête par exemple). Or, les mesures de contamination surfacique bêta ne peuvent pas toujours être réalisées au plus près des chantiers. Le bruit de fond gamma présent à ces endroits étant élevé et fluctuant, ce dernier perturbe les appareils utilisés habituellement pour la mesure de contamination surfacique. L’objectif principal de ce travail était de concevoir un appareil de mesure adapté à la détection de contamination surfacique bêta de quelques Bq/cm2 (typiquement < 4 Bq/cm2), dans une ambiance gamma de quelques dizaines de µSv/h (typiquement < 100 µSv/h) et fluctuante (typiquement de l’ordre de 30% en 1 seconde). / In the framework of the nuclear power plants maintenance, the onsite workers incontrolled areas must performed some surface contamination controls of their tools, gloves, workingsuits and over their body parts which may be contaminated (neck and head for instance). However,surface beta contamination measurements can’t always been done as close as possible of the working location. The onsite ambient gamma background, being high and fluctuating, may disturb the radiation protection devices commonly used for surface contamination measurements.The main goal of this work was to conceive a radiation protection device adapted to the betasurface contamination of about a few Bq/cm2 (< 4Bq/cm2 typicaly) in a fluctuating (typicaly 30%variation per second) ambient gamma background of a few μSv/h (typicaly <100 μSv/h).

Suite à un état de l'art détaillant la création et l'utilisation de l'espace sonore dans divers environnements urbains virtuels (soundmaps, jeux vidéo, réalité augmentée), il s'agira de déterminer une méthodologie et des techniques de conception pour les espaces sonores urbains virtuels du point de vue de l'immersion, de l'interface et de la dramaturgie.ces développements se feront dans le cadre du projet terra dynamica, tendant vers une utilisation plurielle de la ville virtuelle (sécurité et sureté, transports de surface, aménagement de l'urbanisme, services de proximité et citoyens, jeux). le principal objectif du doctorat sera de déterminer des réponses informatiques concrètes à la problématique suivante : comment, en fonction de leur utilisation anticipée, les espaces sonores urbains virtuels doivent-ils être structurés et avec quels contenus?la formalisation informatique des solutions étayées au fil du doctorat et la création du contenu sonore illustrant le projet seront basés sur l'analyse de données scientifiques provenant de domaines variés tels que la psychologie de la perception, l'architecture et l'urbanisme, l'acoustique, la recherche esthétique (musicale) ainsi que sur l'observation et le recueil de données audio-visuelles du territoire urbain, de manière à rendre compte tant de la richesse du concept d'espace sonore que de la multiplicité de ses déclinaisons dans le cadre de la ville virtuelle. / In video gaming and interactive media, the making of complex sound ambiences relies heavily on the allowed memory and computational resources. So a compromise solution is necessary regarding the choice of audio material and its treatment in order to reach immersive and credible real-time ambiences. Alternatively, the use of procedural audio techniques, i.e. the generation of audio content relatively to the data provided by the virtual scene, has increased in recent years. Procedural methodologies seem appropriate to sonify complex environments such as virtual cities.In this thesis we specifically focus on the creation of interactive urban sound ambiences. Our analysis of these ambiences is based on the Soundscape theory and on a state of art on game oriented urban interactive applications. We infer that the virtual urban soundscape is made of several perceptive auditory grounds including a background. As a first contribution we define the morphological and narrative properties of such a background. We then consider the urban background sound as a texture and propose, as a second contribution, to pinpoint, specify and prototype a granular synthesis tool dedicated to interactive urban sound backgrounds.The synthesizer prototype is created using the visual programming language Pure Data. On the basis of our state of the art, we include an urban ambiences recording methodology to feed the granular synthesis. Finally, two validation steps regarding the prototype are described: the integration to the virtual city simulation Terra Dynamica on the one side and a perceptive listening comparison test on the other.

No description available.

The main aim of this thesis was to investigate the occurrence of dolphins in Pacific waters adjacent to the Panama Canal in the context of biological, temporal and spatial factors. Acoustic data were collected at 101 sites at a range of distances and depths from the shipping region. Data were collected between March 2010 and April 2011 in a diurnal cycle over a total of 114 recording days. Received sound levels were split into 1/3 Octave bandwidths to study variation in sound pressure levels and then converted to spectrum density levels to show the sound components of the background noise in this region. Generalised Linear Models were used to relate dolphin whistle detections to temporal, spatial, environmental and acoustic variables. The major sources of background noise were biological noise from soniferous fish and snapping shrimp and anthropogenic noise from vessels characterised by mid to high frequencies produced by artisanal fishing boats. There was monthly and diurnal variation with some locations characterised by loud sounds in the mid to high frequencies at night. Whistle characteristics analysis revealed that the frequencies and range of the whistles were different to those previously reported under similar conditions. Whistles varied diurnally and in the presence of fish chorus and fishing boats. The study highlights a strong correlation between fish choruses and whistle detection. Temporal and spatial models showed that whistle detections varied monthly and in relation to fish noise and small vessel engine noise. Dolphins were distributed throughout most of the study area; however, whistle detections varied with distance from the coast. The results provide new knowledge about background noise composition in this region and provide the first information on the ecology of dolphin whistles in relation to this background noise, especially to fish chorus.

Mouse embryonic stem cells (mESCs) can be maintained in a proliferative and undifferentiated state over many passages (self-renewal) while retaining the potential to give rise to every cell type of the organism (pluripotency). Autocrine FGF4/Erk signalling has been identified as a major stimulus for fate decisions and lineage commitment in these cells. Recent findings on serum-free culture conditions with specific inhibitors (known as 2i) demonstrate that the inhibition of this pathway reduces transcription factor heterogeneity and is vital to maintain ground state pluripotency of mESCs. We suggest a novel mathematical model to explicitly integrate FGF4/Erk signalling into an interaction network of key pluripotency factors (namely Oct4, Sox2, Nanog and Rex1). The envisaged model allows to explore whether and how proposed mechanisms and feedback regulations can account for different expression patterns in mESC cultures. We demonstrate that an FGF4/Erk-mediated negative feedback is sufficient to induce molecular heterogeneity with respect to Nanog and Rex1 expression and thus critically regulates the propensity for differentiation and the loss of pluripotency. Furthermore, we compare simulation results on the transcription factor dynamics in different self-renewing states and during differentiation with experimental data on a Rex1GFPd2 reporter cell line using flow cytometry and qRT-PCR measurements. Concluding from our results we argue that interaction between FGF4/Erk signalling and Nanog expression qualifies as a key mechanism to manipulate mESC pluripotency. In particular, we infer that ground state pluripotency under 2i is achieved by shifting stable expression pattern of Nanog from a bistable into a monostable regulation impeding stochastic state transitions. Furthermore, we derive testable predictions on altering the degree of Nanog heterogeneity and on the frequency of state transitions in LIF/serum conditions to challenge our model assumptions.