Indicating Commitment: The Notion of dépense in the Study of Ritual and Religion

By analysing two cases from the recent history of Vaishnavism (a temple festival in Vrindavan; the development of the International Society for Krishna Consciousness, or ISKCON), this paper shows that the notion of dépenseas developed by Marcel Mauss, Robert Hertz and Georges Bataille can be applied as an analytical tool in the study of rituals and religion as an indicator of religious commitment. At the same time it is possible to show that, by constructing a kind of macro-economic theory that includes religious behaviour, recent theories of religious economics are part of, and reproduce, a modern discourse of rationality that rules out, rather than understands, forms of irrationality such as unproductive expenditure (dépense).

Minimally invasive photopolymerization in intervertebral disc tissue cavities

Photopolymerized hydrogels are commonly used for a broad range of biomedical applications. As long as the polymer volume is accessible, gels can easily be hardened using light illumination. However, in clinics, especially for minimally invasive surgery, it becomes highly challenging to control photopolymerization. The ratios between polymerization- volume and radiating-surface-area are several orders of magnitude higher than for ex-vivo settings. Also tissue scattering occurs and influences the reaction. We developed a Monte Carlo model for photopolymerization, which takes into account the solid/liquid phase changes, moving solid/liquid-boundaries and refraction on these boundaries as well as tissue scattering in arbitrarily designable tissue cavities. The model provides a tool to tailor both the light probe and the scattering/absorption properties of the photopolymer for applications such as medical implants or tissue replacements. Based on the simulations, we have previously shown that by adding scattering additives to the liquid monomer, the photopolymerized volume was considerably increased. In this study, we have used bovine intervertebral disc cavities, as a model for spinal degeneration, to study photopolymerization in-vitro. The cavity is created by enzyme digestion. Using a custom designed probe, hydrogels were injected and photopolymerized. Magnetic resonance imaging (MRI) and visual inspection tools were employed to investigate the successful photopolymerization outcomes. The results provide insights for the development of novel endoscopic light-scattering polymerization probes paving the way for a new generation of implantable hydrogels.