Computational chemistry studies of UV induced processes in human skin

This thesis presents and uses the techniques of computational chemistry to explore two different processes induced in human skin by ultraviolet light. The first is the transformation of urocanic acid into a immunosuppressing agent, and the other is the enzymatic action of the 8-oxoguanine glycosylase enzyme. The photochemistry of urocanic acid is investigated by time-dependent density functional theory. Vertical absorption spectra of the molecule in different forms and environments is assigned and candidate states for the photochemistry at different wavelengths are identified. Molecular dynamics simulations of urocanic acid in gas phase and aqueous solution reveals considerable flexibility under experimental conditions, particularly for for the cis isomer where competition between intra- and inter-molecular interactions increases flexibility. A model to explain the observed gas phase photochemistry of urocanic acid is developed and it is shown that a reinterpretation in terms of a mixture between isomers significantly enhances the agreement between theory and experiment , and resolves several peculiarities in the spectrum. A model for the photochemistry in the aqueous phase of urocanic acid is then developed, in which two excited states governs the efficiency of photoisomerization. The point of entrance into a conical intersection seam is shown to explain the wavelength dependence of photoisomerization quantum yield. Finally some mechanistic aspects of the DNA repair enzyme 8-oxoguanine glycosylase is investigated with density functional theory. It is found that the critical amino acid of the active site can provide catalytic power in several different manners, and that a recent proposal involving a SN1 type of mechanism seems the most efficient one.

Youth, Religion and Participation : Theoretical and Methodological Approaches

This roundtable session focus on religious and social change as well as democracy and political culture, startingfrom the role of youth in these processes. The role of religion in young people’s participation is a key theme inthe cross-disciplinary network “youth and religion” connected to the Impact program. Participation here includesboth citizens’ “vertical” capacities to make their voices heard and influence decision-makers in the political system(e.g. via elections or civic organizations and social movements) and their “horizontal” capacities to communicateand cooperate with other people (within society at large or certain associations/communities). The participants ofthe session will present influential theories and methodologies used to study participation among youth within theresearch disciplines they represent (i.e. sociology of religion; theology; ethnology; political science). This will befollowed by a joint discussion of how these theories and methodologies have approached religious involvement witha particular focus on youth’s participation in politics, civil society as well as social media and the internet. The aim ofthe session is to look for common themes and new issues that can guide contemporary studies of participation in thefield of youth and religion. The session is open to conference participants interested in the issues discussed.