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1	Formation of protonium and positronium in atomic collisions Whitehead, Richard John January 2001 (has links) A minimum-norm method has been developed for solving the coupled integro-differential equations describing the scattering of positrons by one-electron targets in which the rearrangement channels for positronium formation have been explicitly included. The minimum-norm method, applied to this application for the first time in this thesis, is an enhancement of a previously reported least-squares method which has enabled the extension to a significantly larger basis consisting of up to 26 states on the direct centre, including pseudostates, and 3 states on the positronium. The method has been applied here to e+-H and e+-He+ scattering; cross-sections have been produced for the latter over a range of energies up to 250 eV. The basis was found to be large enough to produce smooth cross sections and little evidence of pseudoresonance structure was found. The results are the first converged cross sections to be calculated for e+-He+ scattering using the coupled channel approximation. Results for e+-H scattering compare well with the work of other authors. A highly efficient parallel code was developed for solving the largest coupling cases. The results prove the minimum-norm approach to be an accurate and reliable method for large-scale coupled channel calculations involving rearrangement collisions. Also in this thesis, the capture of slow antiprotons by atomic hydrogen and positronium has been simulated by the Classical Trajectory Monte Carlo (CTMC) method. Statistically accurate cross sections for protonium and antihydrogen formation have been obtained and the energy dependence of the process established. Antihydrogen formation from antiproton collisions with positronium in the presence of a laser has also been simulated with the CTMC method and the effects of laser polarisation, frequency and intensity studied. Enhancements of the antihydrogen formation cross section were observed and it is suggested that more sophisticated calculations should be undertaken 539.7
2	Lumière vivante : théorie et pratique de la bioluminescence d'après Raphaël Dubois / Living light : theory and practice by Raphaël Dubois Coliac, Nadia 16 May 2018 (has links) C’est une recherche qui s’articule sur une double démarche Art et Science. Elle met en scène une bactérie bioluminescente. Ma réflexion présente la bioluminescence comme une construction intellectuelle et phénoménologique, où la dimension ontologique de la lumière prend tout son sens dans l’idée d’u Contenant Lumière Vivante.La thèse retrace aussi un parcours artistique ponctué de lumière et faite de rencontres humaines et littéraires comme le Petit Prince de Saint-Exupéry. Elle met aussi en lumière ma rencontre d’outre-tombe avec le savant et philosophe Raphaël Dubois 1849-1929, qui m’a ouvert les pistes de recherche sur ses traces de biologiste, sur sa philosophie du Protéon et de la Mémoire en général.Ma réflexion sous-tend une double éthique : celle qui concerne l’honnêteté scientifique par rapport à la mémoire de Dubois et celle liée au droit de réserve, attachée à la pratique du vivant et à la responsabilité qui incombe à tout un chacun. Je pose aussi un regard critique sur la lumière vivante comme phénomène de mode. On peut être séduit par sa qualité esthétique, sa nature intrinsèque de lumière froide et sa finalité, supposée écologique, mais la « pratique » dans la réalité soulève de nombreux problèmes. / This research work is based on a dual approach of art and science. It features a bioluminescent bacterium. My reflection presents bioluminescence as an intellectual and phenomenological construction where the ontological dimension of light takes on its full meaning from the idea of living light container.The thesis also traces my artistic career punctuated by light and human encounters as well as books such as the Little Prince by Saint-Exupéry. It also highlights my meeting from beyond the grave with the scientist and philosopher Raphael Dubois 1849-1929 who opened for me a track of research following his steps as a biologist and a field of reflection on his philosophy of Protéon and on memory in general. My reflection underlies a double ethics, that of scientific honesty in relation to Dubois' memory, and that related to the right of reserve linked to the practice of living and to the responsibility that falls to everyone. I also cast a critical look at this living light as a fashion phenomenon, one may probably be attracted by its aesthetic quality, its intrinsic nature of cold light, and its supposed ecological end, but in fact its « practice » raises many problems. Lumière Mémoire Bioluminescence Phénoménologie Immanence Être On-Tologie Homme Raphaël Dubois Protéon Contenant Vide Vie Expérience Installation Performance Art Architecture Design Science Photobacterium phosphoreum ANT 2200 Bactérie Biologie Écologie Éthique. Light Memory Bioluminescence Phenomenology Immanence Being Ontol-Ogy Man Raphael Dubois Protonium Containing Empty Life Experiment Installation Performance Art Architecture Design Science Photobacterium phosphoreum ANT 2200 Bacteria Biology Ecology Ethics

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Formation of protonium and positronium in atomic collisions

Lumière vivante : théorie et pratique de la bioluminescence d'après Raphaël Dubois / Living light : theory and practice by Raphaël Dubois