Développement de la tomographie intra-vitale au K-edge avec la caméra à pixels hybrides XPAD3

The hybrid pixel camera XPAD3 integrated in the micro-CT PIXSCAN IIis a new devicedeveloped by the imXgam team at CPPM for which photon counting replaces charge integrationused in standard X-ray CT. This novel approach involves advantages, in particularthe absence of dark noise and the ability to set an energy threshold on each pixel of thedetected photons. This features has been exploited during this thesis work for standardsmall animal preclinical imaging and permitted to establish the faisability of ex vivo, andthen in vivo labelling of marcrophages.On another hand, the ability of this camera is of uppermost importance for the developmentof K-edge imaging approaches, which exploit spectral information on the countedphotons. K-edge imaging permits to identify contrast agent compartiments with regardsto bones in classical radiography. K-edge imaging is obtained by selecting, for each pixelcalibration, those pixel that are set at one of the three different thresholds around theK-shell’s binding energy of the selected contrast agents and then, to proceed with a subtractionanalysis to the images obtained above and below the K-edge energy.We develop a new way of calibrating the XPAD3 detector that permits to provide theproof of concept of a patent owned by the imXgam team, and to obtain the first results onliving mice by dividing the acquisition time by three with a compromise on the resolution.This novel approach can be implemented in "two colours" in order to separate clearly twodifferent contrast agents. This brings a new way to visualize biological information and toprovide possible future approaches for the study of the inter-dependance of vascularisationand inflammation during the tumor development.La caméra à pixels hybrides XPAD3 intégrée dans le micro-tomodensitomètre PIXSCANII est un nouveau dispositif développé par l’équipe imXgam au CPPM dans lequelle comptage de photons remplace l’intégration de charges utilisée dans les systèmes deradiographie standard. La caméra XPAD3 apporte des avantages, en particulier l’absencede bruit de courant noir et la possibilité d’imposer un seuil de discrimination sur chaquepixel. Ces particularités ont pu être exploitées au cours de ce travail de thèse en imageriepréclinique classique sur petit animal et ont permis de faire la preuve de faisabilité d’unmarquage ex-vivo puis intra-vital des macrophages.D’autre part les capacités de cette caméra sont intéressantes pour le développement d’unenouvelle méthode d’imagerie spectrale dite au K-edge. L’imagerie au K-edge permet dedifférencier des compartiments contenant un agent de contraste par rapport à l’os dans desradiographies classiques. Elle est obtenue via l’étalonnage de trois différents seuils autourde l’énergie de liaison de la couche K de l’agent de contraste considéré. Le développementd’un nouvel d’étalonnage avec l’utilisation de pixels composites a permis d’établir la preuvede concept d’un brevet déposé par l’équipe imXgam et d’obtenir les premiers résultatssur souris vivantes en divisant le temps d’acquisition par trois avec un compromis sur larésolution spatiale.Cette nouvelle approche peut être implémentée en « deux couleurs » pour séparer deuxdifférents types d’agents de contraste. Ceci offre une nouvelle manière de visualiser desinformations biologiques pertinentes dans un contexte applicatif visant à étudier de manièredynamique (longitudinale) l’interdépendance de la vascularisation et de la réponseimmunitaire au cours du développement tumoral

Influence of Music on Perceived Emotions in Film

Film music plays a core role in film production and reception as it not only contributes to the film aesthetics and creativity, but it also affects viewers' experience and enjoyment. Film music composers often aim to serve the film narrative, immerse viewers into the setting and story, convey clues, and importantly, act on their emotions. Yet, how film music influences viewers is still misunderstood. We conducted a perceptual study to analyse the impact of music on the perception of emotions in film. We developed an online interface for time-based emotion annotation of audio/video media clips based on the Valence/Arousal (VA) two-dimensional model. Participants reported their perceived emotions over time in the VA space for three media conditions: film scene presented without sound (video only), film music presented without video (audio only), and film scene with accompanying music and sound effects (both video and audio modalities). 16 film clips were selected covering four clips for each of four genres (action & drama, romance, comedy, and horror). 38 participants completed the study (12 females and 26 males from many countries, average age: 28.9). Density scatter plots are used to visualise the spread of emotion ratings in the VA space and differences across media conditions and film clips. Results from linear mixed effect models show significant effects of the audiovisual media condition and film genre on VA ratings, in line with previous results by Parke et al. [1]. Perceived VA ratings across media conditions follow an almost linear relationship with an increase in strength in the following order: film alone, film with music/sound, music alone. We illustrate this effect by plotting the VA rating centre of mass across conditions. VA ratings for the film-alone condition are closer to the origin of the space compared to the two other media conditions, indicating that the inclusion of music yields stronger emotions (higher VA ratings). Certain individual factors (musical ability, familiarity, preference) also seem to impact the perception of arousal and valence while viewing films. Our online emotion annotation interface was on overall well received and suggestions to improve the display of reference emotion tags are discussed

Timbre from Sound Synthesis and High-level Control Perspectives

International audienceExploring the many surprising facets of timbre through sound manipulations has been a common practice among composers and instrument makers of all times. The digital era radically changed the approach to sounds thanks to the unlimited possibilities offered by computers that made it possible to investigate sounds without physical constraints. In this chapter we describe investigations on timbre based on the analysis by synthesis approach that consists in using digital synthesis algorithms to reproduce sounds and further modify the parameters of the algorithms to investigate their perceptual relevance. In the first part of the chapter timbre is investigated in a musical context. An examination of the sound quality of different wood species for xylophone making is first presented. Then the influence of instrumental control on timbre is described in the case of clarinet and cello performances. In the second part of the chapter, we mainly focus on the identification of sound morphologies, so called invariant sound structures responsible for the evocations induced by environmental sounds by relating basic signal descriptors and timbre descriptors to evocations in the case of car door noises, motor noises, solid objects, and their interactions

Design and perceptual evaluation of a fully immersive three-dimensional sound spatialization system

International audienceThis article presents the design, the implementation, and the perceptual evaluation of a multichannel loudspeaker array for the creation of 3D virtual sound environments. Dedicated to perceptual and postural studies, this system consists of 42 loudspeakers equally distributed around the listener on a full sphere (3 meter diameter), allowing to synthetize sounds moving within the whole 3D space. The spatial distribution of the loudspeakers makes it possible to use two different 3D rendering approaches: a physical approach through the use of 3D Higher Order Ambisonics (HOA) method up to fifth order and a perceptual approach through the use of Vector-Based Amplitude Panning (VBAP) method. A localization experiment was carried out in order to investigate the performance of the present system in terms of localization accuracy. Furthermore, this experiment aimed to explore the perceptual impact of the rendering methods (e.g. HOA and VBAP), and to evaluate the improvement of localization performance with respect to the ambisonic order (from third to fifth order). Differences between rendering methods are investigated in terms of azimuth and elevation localization errors, and front-back and up-down confusions. Finally, virtual sound source localization is compared to real sound source localization generated by 42 loudspeakers