@misc{Galetzka2018, type = {Master Thesis}, author = {Galetzka, Cedric}, title = {Reward and prediction errors in Bayesian sensorimotor control}, doi = {10.25932/publishup-50350}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-503507}, school = {Universit{\"a}t Potsdam}, pages = {53}, year = {2018}, abstract = {Midbrain dopamine neurons invigorate responses by signaling opportunity costs (tonic dopamine) and promote associative learning by encoding a reward prediction error signal (phasic dopamine). Recent studies on Bayesian sensorimotor control have implicated midbrain dopamine concentration in the integration of prior knowledge and current sensory information. The present behavioral study addressed the contributions of tonic and phasic dopamine in a Bayesian decision-making task by alternating reward magnitude and inferring reward prediction errors. Twenty-four participants were asked to indicate the position of a hidden target stimulus under varying prior and likelihood uncertainty. Trial-by-trial rewards were allocated based on performance and two different reward maxima. Overall, participants' behavior agreed with Bayesian decision theory, but indicated excessive reliance on likelihood information. These results thus oppose accounts of statistically optimal integration in sensorimotor control, and suggest that the sensorimotor system is subject to additional decision heuristics. Moreover, higher reward magnitude was not observed to induce enhanced response vigor, and was associated with less Bayes-like integration. In addition, the weighting of prior knowledge and current sensory information proceeded independently of reward prediction errors. Taken together, these findings suggest that the process of combining prior and likelihood uncertainties in sensorimotor control is largely robust to variations in reward.}, language = {en} } @misc{Steiglechner2018, type = {Master Thesis}, author = {Steiglechner, Peter}, title = {Estimating global warming from anthropogenic heat emissions}, doi = {10.25932/publishup-49886}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-498866}, school = {Universit{\"a}t Potsdam}, year = {2018}, abstract = {The forcing from the anthropogenic heat flux (AHF), i.e. the dissipation of primary energy consumed by the human civilisation, produces a direct climate warming. Today, the globally averaged AHF is negligibly small compared to the indirect forcing from greenhouse gas emissions. Locally or regionally, though, it has a significant impact. Historical observations show a constant exponential growth of worldwide energy production. A continuation of this trend might be fueled or even amplified by the exploration of new carbon-free energy sources like fusion power. In such a scenario, the impacts of the AHF become a relevant factor for anthropogenic post-greenhouse gas climate change on the global scale, as well. This master thesis aims at estimating the climate impacts of such a growing AHF forcing. In the first part of this work, the AHF is built into simple and conceptual, zero- and one-dimensional Energy Balance Models (EBMs), providing quick order of magnitude estimations of the temperature impact. In the one-dimensional EBM, the ice-albedo feedback from enhanced ice melting due to the AHF increases the temperature impact significantly compared to the zero-dimensional EBM. Additionally, the forcing is built into a climate model of intermediate complexity, CLIMBER-3α. This allows for the investigation of the effect of localised AHF and gives further insights into the impact of the AHF on processes like the ocean heat uptake, sea ice and snow pattern changes and the ocean circulation. The global mean temperature response from the AHF today is of the order of 0.010 - 0.016 K in all reasonable model configurations tested. A transient tenfold increase of this forcing heats up the Earth System additionally by roughly 0.1 - 0.2 K in the presented models. Further growth can also affect the tipping probability of certain climate elements. Most renewable energy sources do not or only partially contribute to the AHF forcing as the energy from these sources dissipates anyway. Hence, the transition to a (carbon-free) renewable energy mix, which, in particular, does not rely on nuclear power, eliminates the local and global climate impacts from the increasing AHF forcing, independent of the growth of energy production.}, language = {en} } @misc{Reger2018, type = {Master Thesis}, author = {Reger, Carolin}, title = {Dating of alluvial fans from NW Argentina using cosmogenic nuclides and optically stimulated luminescence technique}, doi = {10.25932/publishup-47147}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-471470}, school = {Universit{\"a}t Potsdam}, pages = {4, IV}, year = {2018}, abstract = {Alluvial fans are important geomorphic markers and sedimentary archives of tectonic and climatic changes. Hence, basins providing perfect studying conditions can often be found in arid regions due to the low weathering impact and thus well preservation of sedimentary features. Twelve samples for optically/infrared stimulated luminescence (OSL/IRSL) dating and one depth profile for cosmogenic radionuclide dating (10Be) were collected in the Santa Maria Valley in NW Argentina, where the exceptional preservation of several generations of alluvial fans allow exploring the external forcing conditions that led to repeated cycles of incision and aggradation. The results of the OSL/IRSL dating yielded ages ranging between 0.4 ± 0.1 ka and 271.8 ± 24.5 ka. Previous studies next to the study area indicate a depositional age of 1.5-2 Mio years for the oldest generation of alluvial fans, which might still be supported by our ongoing 10Be dating. Due to field observations, sediment provenance, stratigraphic characteristics and the geomorphic pattern of erosion, seven (/eight) generations of alluvial fan deposits were recognized. Comparing my ages with global glaciation cycles as well as linking them to temperature proxies retrieved from a lake on the Altiplano Plateau, a good fit between alluvial fan accumulation phases and global glacial periods (corresponding to cold/wet phases within the central Andes) is observed. This suggests that aggradation occurs during the early stages of glacial periods, while incision is expected at the end of glacial phases. This pattern might be linked to variations in the vegetational cover (controlled by water availability), which will decrease/increase during hot and dry/cold and wet interglacial/glacial phases favoring/limiting sediment production and will increase/decrease during cold and wet/hot and dry glacial/interglacial phases. Even though the eastern Andean margin is showing neotectonic activities and is assumed to be active up to recent times, deformation and seismicity might most probably have played only a minor role in relation to the rather short timescale reflected by the data.}, language = {en} } @misc{Holtz2018, type = {Master Thesis}, author = {Holtz, Johannes Niklas}, title = {Civil servants' commitment to change - a factor of success regarding the reform of public budgeting and accounting in the State of Brandenburg?}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {2190-4561}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-420792}, school = {Universit{\"a}t Potsdam}, pages = {IV, 79}, year = {2018}, abstract = {This study investigates the reform of the public budgeting and accounting system (Doppik) in Brandenburg. On the one hand, this thesis aims to identify the key variables shaping employees' commitment to change and, on the other hand, to examine the extent employees' commitment to change influences the implementation process of the reform. The results of this study show that the commitment of civil servants towards the Doppik is primarily determined by the content, but also by the context of the reform. Moreover, it is revealed for the case of Brandenburg that civil servants' affective commitment to change has a significant positive influence on the perceived success of the reform implementation. The results of the study are not only of high scientific importance, but also of practical relevance. The recommendations developed in this study offer grounded guidelines on how to successfully implement the Doppik on local level in Brandenburg.}, language = {en} }