An Evolutionary Argument for a Self-Explanatory, Benevolent Metaphysics

In this paper, a metaphysics is proposed that includes everything that can be represented by a well-founded multiset. It is shown that this metaphysics, apart from being self-explanatory, is also benevolent. Paradoxically, it turns out that the probability that we were born in another life than our own is zero. More insights are gained by inducing properties from a metaphysics that is not self-explanatory. In particular, digital metaphysics is analyzed, which claims that only computable things exist. First of all, it is shown that digital metaphysics contradicts itself by leading to the conclusion that the shortest computer program that computes the world is infinitely long. This means that the Church-Turing conjecture must be false. Secondly, the applicability of Occam’s razor is explained by evolution: in an evolving physics it can appear at each moment as if the world is caused by only finitely many things. Thirdly and most importantly, this metaphysics is benevolent in the sense that it organizes itself to fulfill the deepest wishes of its observers. Fourthly, universal computers with an infinite memory capacity cannot be built in the world. And finally, all the properties of the world, both good and bad, can be explained by evolutionary conservation

Lipschitzness Is All You Need To Tame Off-policy Generative Adversarial Imitation Learning

Despite the recent success of reinforcement learning in various domains, these approaches remain, for the most part, deterringly sensitive to hyper-parameters and are often riddled with essential engineering feats allowing their success. We consider the case of off-policy generative adversarial imitation learning, and perform an in-depth review, qualitative and quantitative, of the method. We show that forcing the learned reward function to be local Lipschitz-continuous is a sine qua non condition for the method to perform well. We then study the effects of this necessary condition and provide several theoretical results involving the local Lipschitzness of the state-value function. We complement these guarantees with empirical evidence attesting to the strong positive effect that the consistent satisfaction of the Lipschitzness constraint on the reward has on imitation performance. Finally, we tackle a generic pessimistic reward preconditioning add-on spawning a large class of reward shaping methods, which makes the base method it is plugged into provably more robust, as shown in several additional theoretical guarantees. We then discuss these through a fine-grained lens and share our insights. Crucially, the guarantees derived and reported in this work are valid for any reward satisfying the Lipschitzness condition, nothing is specific to imitation. As such, these may be of independent interest

Metarel, an ontology facilitating advanced querying of biomedical knowledge

Knowledge management has become indispensible in the Life Sciences for integrating and querying the enormous amounts of detailed knowledge about genes, organisms, diseases, drugs, cells, etc. Such detailed knowledge is continuously generated in bioinformatics via both hardware (e.g. raw data dumps from micro‐arrays) and software (e.g. computational analysis of data). Well‐known frameworks for managing knowledge are relational databases and spreadsheets. The doctoral dissertation describes knowledge management in two more recently‐investigated frameworks: ontologies and the Semantic Web. Knowledge statements like ‘lions live in Africa’ and ‘genes are located in a cell nucleus’ are managed with the use of URIs, logics and the ontological distinction between instances and classes. Both theory and practice are described. Metarel, the core subject of the dissertation, is an ontology describing relations that can bridge the mismatch between network‐based relations that appeal to internet browsing and logic‐based relations that are formally expressed in Description Logic. Another important subject of the dissertation is BioGateway, which is a knowledge base that has integrated biomedical knowledge in the form of hundreds of millions of network‐based relations in the RDF format. Metarel was used to upgrade the logical meaning of these relations towards Description Logic. This has enabled to build a computer reasoner that could run over the knowledge base and derive new knowledge statements

Le travail des préventeurs en entreprise : Contribution méthodologique à la visite de sécurité

Our thesis is in line with a first research work in which we highlighted the use by OSH to accommodation of some instructions during safety inspections. This has raised new questions about the consequences of this phenomenon on the health of the OSH but also on the performance of the safety management system. Our thesis then focused on the characterization of the difficulties encountered by OSH during problem solving sequences initiated by the detection of deviations from the prescription safety during the visit, but also on identifying methodological determinants that are at the origin. Three methods were used: statement traces of the activity using the method of the agenda, open observations of the activity of a sample of OSH enterprises and systematic observations visit phases security coupled with verbalisation techniques. The main results of this thesis are: (i) OSH in companies only spend very little time for safety inspections, (ii) the phenomenon of "desertion" of the land can’t be solely explained by the weight of administrative tasks (iii) the temporal context in which are carried out safety inspections and the lack of media artifact exchanges, do not favor the development of cognitive synchronization phenomenon, since all differences are not explicitly approved by surveying the solutions of all interlocutors, (iv) OSH develop defense strategies reducing the effects of this lack of performance on their health, (v) changes in the temporal context and the integration of video artifacts facilitating trade, allows improved performance in terms of deviations lifted; the solutions produced are then more numerous and more complex, exchanges are richer and constraints are better managed. The results of this thesis allow both to continue with the characterization of the work of OHS in companies, to account for the effects of self-confrontation on interviewers but also to offer an artifact design method based on the instrumental approach which facilitates ownership.Notre thèse s’inscrit dans la lignée d’un premier travail de recherche durant lequel nous avions mis en évidence le recours par les préventeurs à l’accommodation de certaines consignes au cours des visites de sécurité. Ce résultat a suscité de nouveaux questionnements quant aux conséquences de ce phénomène sur leur santé mais aussi sur les performances du système de management de la sécurité. Notre travail de thèse s’est ainsi centré sur la caractérisation des difficultés rencontrées par les préventeurs lors des séquences de résolution de problèmes initiées par la mise en évidence d’écarts à la prescription au cours de la visite de sécurité mais aussi sur l’identification des déterminants méthodologiques qui en sont à l’origine. Trois méthodes ont été utilisées : des relevés des traces de l’activité à l’aide de la méthode de l’agenda, des observations ouvertes de l’activité d’un échantillon préventeurs en entreprise et des observations systématiques des phases de visites de sécurité couplées à des techniques de verbalisations. Les principaux résultats de cette thèse sont que : (i) les préventeurs en entreprise ne consacrent que très peu de temps aux visites de sécurité, (ii) ce phénomène de "désertion" du terrain ne peut être uniquement expliqué par le poids des tâches administratives, (iii) le contexte temporel dans lequel sont réalisées les visites de sécurité et l’absence d’artefact support pour les échanges ne favorisent pas le développement du phénomène de synchronisation cognitive puisque tous les écarts ne sont pas levés par des solutions explicitement approuvées par l’ensemble des interlocuteurs, (iv) les préventeurs développent des stratégies de défense pour réduire les effets de ce manque de performance sur leur santé, (v) les modifications du contexte temporel et l’intégration de l’artefact vidéo facilitant les échanges permettent d’améliorer les performances en matière de résolution de problèmes et de développer dans quelques mesures la santé des préventeurs; les solutions produites sont alors plus nombreuses ou plus complexes, les échanges plus riches et les contraintes mieux gérées. Les résultats de cette thèse permettent à la fois de poursuivre la caractérisation du travail des préventeurs en entreprise, de rendre compte des effets de l’autoconfrontation sur les interviewers mais aussi de proposer une méthode de conception d’artefact basée sur l’approche instrumentale qui facilite l’appropriation

Utilisation des technologies d'impression pour le remplissage industriel des trous d'interconnexion

Ce mémoire porte sur l'étude de faisabilité technique du remplissage des trous d'interconnexion par impression jet d'encre appliquée aux procédés de microfabrication MEMS "via last". Le but du projet est de développer un procédé complet viable basé sur l'utilisation de dispersions d'alliages de nanoparticules d'or/étain (Au80Sn20) en suspension. Nos travaux ont porté principalement sur la mise en suspension stable des nanoparticules ainsi que le remplissage à haute précision des trous d'interconnexion. Nous avons d'abord développé un procédé de mise en suspension stable des nanoparticules dans un fluide porteur basé sur l'utilisation d'un surfactant, le polyvinylpyrrolidone (PVP). De nombreux essais de mise en suspension effectués sur différents solvants ont permis de déterminer que l'isopropanol constituait le meilleur fluide porteur en permettant d'atteindre des fractions volumiques en nanoparticules de l'ordre de 11%. Les conditions de génération stable des monogouttes par impression jet d'encre ont ensuite été analysées. En effet, la génération de microgouttes monodispersées par jet d'encre est un procédé complexe, partiellement décrit par la théorie de Fromm et la théorie des guides d'ondes, nécessitant le respect de conditions d'opérations précises que nous avons dû définir afin d'être en mesure de maitriser précisément leur volume et leur vitesse d'éjection. Nous avons défini un modèle de zone d'éjectabilité utilisable universellement pour la génération des microgouttes en caractérisant les paramètres de sorties des microgouttes en fonction de l'amplitude, la largeur et la fréquence de l'impulsion envoyée à l'actionneur piézoélectrique dans la tête d'impression de 50 μm de diamètre d'ouverture utilisée au cours de notre étude. Nous avons également développé un modèle théorique de la cinématique de chute des microgouttes lors de l’impression afin de comprendre et d’analyser l'influence du volume et de la vitesse des gouttes ainsi éjectées sur la précision, la reproductibilité et l'homogénéité des dépôts en présence de fluctuations dans l'air. Ce modèle a été transposé numériquement sous MATLAB afin permettre une validation expérimentale dans des conditions d'opérations réelles. Nos résultats ont permis d'évaluer qu'en utilisant une tête d'impression de 50 μm d’ouverture pour générer des microgouttes d'un diamètre situé entre 30 et 60 μm on s'attendra à obtenir une erreur de placement maximale sur le substrat de l'ordre de ± 20 μm. Il sera alors envisageable remplir des TSVs d'une ouverture minimale de 70 μm avec notre procédé.----------Abstract This master project concerns a feasibility study about the use of inkjet drop-on-demand to fill through silicon vias in MEMS "via last" microfabrication process. The aim of our research was to develop a comprehensive process based on the use of a dispersion of a gold/tin alloy (Au80Sn20) of nanoparticles in suspension in a carrier fluid. Our work mainly focused on the preparation of stable suspensions of nanoparticles and on the high precision filling of the vias. We first developed a method to form a stable suspension of nanoparticles in a carrier fluid using a surfactant, polyvinylpyrrolidone (PVP). Tests performed on various solvents allowed us to determine that isopropanol was the best carrier fluid to achieve high volume fractions of suspended nanoparticles. The volume fraction of the stable dispersion with the highest content reached 11%. The conditions to generate stable individual microdroplets from a piezoelectric printing actuator were then analyzed. The generation of monodisperse microdroplets beiing a complex process, partly described by Fromm's theory and the theory of waveguides, we investigated the operating conditions permitting to precisely set the drop volume and ejection velocity. We therefore characterized an "ejectability zone" model universally usable to generate microdrops with desired output parameters based on the amplitude, width, and frequency of the electric pulse applied to the piezoelectric actuator of a print head having a 50 μm diameter aperture. We also developed a theoretical kinematical model describing the trajectories of microdrops during printing in order to understand the influence of their volume and initial velocity on the accuracy, reproducibility and homogeneity of the deposits in the presence of air fluctuations. This model was implemented in MATLAB and validated in real operating conditions. The results showed that a print head with a 50 μm diameter aperture will generate microdroplets with diameters between 30 and 60 microns with a maximum placement error on the substrate of the order of ± 20 microns. We estimated that filling TSVs with an opening of 70 microns and higher is possible with our inkjet DOD (non defined) process. Finally, we experimentally addressed the vias filling by studying the behavior of nanoparticles in the vias during the evaporation of the carrier fluid and the annealing of the gold/tin alloy nanoparticles of eutectic composition. This last step revealed the incompatibility of non

Studying Nanoparticle Penetration in 3D Multicellular Tumour Models On-Chip

Here, we report a breast tumour-on-a-chip platform to evaluate the penetration of nanomedicines in 3D tumour spheroids, as a function of the tumour spheroid cellular composition. Mouse multicellular tumour mono-culture spheroids and cancer cell-fibroblast co-culture spheroids were exposed to silica nanoparticles (NPs) (30 or 100nm) or liposomes (100nm) at various flowrates, mimicking the shear stress levels found in vivo. Results revealed that the NP penetration was influenced by the shear stress, and that the presence of fibroblasts in the tumour spheroids greatly reduced the penetration depth of the nanoparticles