The central circadian pacemaker in mammals, the suprachiasmatic nucleus (SCN), is important for daily as well as seasonal rhythms. The SCN encodes seasonal changes in day length by adjusting phase... Show moreThe central circadian pacemaker in mammals, the suprachiasmatic nucleus (SCN), is important for daily as well as seasonal rhythms. The SCN encodes seasonal changes in day length by adjusting phase distribution among oscillating neurons thereby shaping the output signal used for adaptation of physiology and behavior. It is well-established that brief light exposure at the beginning and end of the day, also referred to as "skeleton" light pulses, are sufficient to evoke the seasonal behavioral phenotype. However, the effect of skeleton light exposure on SCN network reorganization remains unknown. Therefore, we exposed mice to brief morning and evening light pulses that mark the time of dawn and dusk in a short winter- or a long summer day. Single-cell PER2::LUC recordings, electrophysiological recordings of SCN activity, and measurements of GABA response polarity revealed that skeleton light-regimes affected the SCN network to the same degree as full photoperiod. These results indicate the powerful, yet potentially harmful effects of even relatively short light exposures during the evening or night for nocturnal animals. Show less
Kooijman, S.; Berg, R. van den; Ramkisoensing, A.; Boon, M.R.; Kuipers, E.N.; Loef, M.; ... ; Rensen, P.C.N. 2015
In the last three decades, the Life Cycle Assessment (LCA) framework has grown to establish itself as the leading tool for the assessment of the environmental impacts of product systems.LCA studies... Show moreIn the last three decades, the Life Cycle Assessment (LCA) framework has grown to establish itself as the leading tool for the assessment of the environmental impacts of product systems.LCA studies are now conducted globally both in and outside the academia and also used as a basis for policy making.Now that the science behind existing and established impact assessment models is more solid, LCA modellers may work on deepening and broadening LCA, and on tackling the issues that make the framework incomplete or uncertain.This work of thesis deals with the complete modelling of stressors that are not related to the standard extraction/emission pattern, thus that do not relate to the extraction of a certain quantity of matter or to the emission of matter to the environment.These stressors may be defined in this acceptation as matter-less.The thesis analyses the development of impact assessment models for the case of sound emissions determining noise impacts, radio-frequency electromagnetic emissions leading to electromagnetic pollution, and light emissions determining ecological light pollution.Through the study of these matter-less stressors the computational structure and other methodological topics of the LCA framework are put to the test. Show less
