Harmonic Maps into Trees and Graphs : Analytical and Numerical Aspects

The main topic of this work is the definition and investigation of a nonlinear energy for maps with values in trees and graphs and the analysis of the corresponding nonlinear Dirichlet problem. The nonlinear energy is defined using a semigroup approach based on Markov kernels and the nonlinear Dirichlet problem is given as a minimizing problem of the nonlinear energy. Conditions for the existence and uniqueness of a solution to the nonlinear Dirichlet problem are presented. A numerical algorithm is developed to solve the nonlinear Dirichlet problem for maps from a two dimensional Euclidean domain into trees. The problem is discretized using a suitable finite element approach and convergence of a corresponding iterative numerical method is proven. Furthermore, for graph targets homotopy problems are analyzed. For particular domain spaces the existence of a minimizer of the nonlinear energy in a given homotopy class is shown

No evidence for top-down expertise effects on action perception in sprinters using static images.

Athletes have been found to demonstrate a superior ability to detect subtle variations in dynamic displays (e.g., point-light displays and videos) depicting expert actions compared to non-athletes. The current study aimed to determine whether this advantage also exists when dynamic information is unavailable (i.e., using static images). Using a staircase procedure, two frames from a video depicting an athlete either walking (everyday action) or performing a sprint start (expert action) were presented, and athletes (sprinters) and non-athletes were asked to indicate whether the images were identical or different. We examined whether presenting the images sequentially (temporal task) or simultaneously (spatial task) influenced participants' discrimination performance. We predicted that the sprinters would outperform the non-sprinters in the spatial task as body postures could be compared directly but not in the temporal task due to larger representational momentum effects for athletes. Contrary to our hypotheses, the sprinters and non-sprinters performed similarly in all tasks and conditions. In line with the prediction that representational momentum may impair performance, participants' thresholds were lower for the spatial than the temporal task. However, post-hoc analysis suggested that this effect is likely to be better explained by a task order effect whereby participants who completed the temporal task first exhibited an advantage in the spatial task, while there were no performance differences for participants who completed the opposite task order. In sum, our results provide no evidence for the idea that motor expertise affects action perception (i.e., perceptual resonance) in a simple psychophysical task employing static images

Temporal-order judgement task suggests chronological action representations in motor experts and non-experts

Peer reviewedPostprintPublisher PD

Local Traffic Safety Analyzer – Improved Road Safety and Optimized Signal Control for Future Urban Intersections

Improving road safety and optimizing the traffic flow – these are major challenges at urban intersections. In particular, strengthening the needs of vulnerable road users (VRUs) such as pedestrians, cyclists and e-scooter drivers is becoming increasingly important, combined with support for automated and connected driving. In the LTSA project, a new system is being developed and implemented exactly for this purpose. The LTSA is an intelligent infrastructure system that records the movements of all road users in the vicinity of an intersection using a combination of several locally installed sensors e.g. video, radar, lidar. AI-based software processes the detected data, interprets the movement patterns of road users and continuously analyzes the current traffic situation (digital twin). Potentially dangerous situations are identified, e.g. right turning vehicles and simultaneously crossing VRUs, and warning messages can be sent to connected road users via vehicle-to-infrastructure communication (V2X). Automated vehicles can thus adapt their driving maneuvers. In addition, the collected data is applied to improve traffic light control depending on the current traffic situation, especially for VRUs. This abstract describes the LTSA system and its implementation in the German city of Potsdam. The current project state is presented and an outlook on next steps is given

Grasping tiny objects

Peer reviewe

Action Perception in Athletes : Expertise Facilitates Perceptual Discrimination

Open Access via the Sage AgreementPeer reviewedPublisher PD

Calculi in Hydrocele: Incidence and Results of Infrared Spectroscopy Analysis

Trauma, inflammation, or necrosis in the scrotal cavity may lead to depositing of organic material in hydrocele fluid with consecutive calcification if the fluid is oversaturated. During a period of 25 years, 2 scrotal calculi (calculous material in hydrocele fluid) in 2 of 42 patients (4.8%) were found during surgery on symptomatic hydroceles by the first author. In these symptomatic cases, infrared spectroscopy revealed carbonate apatite as the causative mineral. The appearance of scrotal calculi in hydrocele does not change the treatment or prognosis of hydroceles. However, if the calculous material is attached to the visceral or parietal part of the tunica vaginalis and does not change position during sonography with different postures, tumor growth may be a problem. An inguinal approach for operation should be chosen in such situations. Infrared spectroscopy can be used to determine the mineralogy of scrotal calculi. Carbonate apatite, the predominantly found mineral in scrotal calculi, can precipitate in an alkaline milieu

Assessment of Socio-Economic and Climate Change Impacts on Water Resources in Four European Lagoon Catchments

This study demonstrates the importance of considering potential land use and management changes in climate impact research. By taking into account possible trends of economic development and environmental awareness, we assess effects of global warming on water availability and quality in the catchments of four European lagoons: Ria de Aveiro (Portugal), Mar Menor (Spain), Vistula Lagoon (Poland and Russia), and Tyligulskyi Liman (Ukraine). Different setups of the process-based soil and water integrated model (SWIM), representing one reference and four socio-economic scenarios for each study area: the “business as usual”, “crisis”, “managed horizons”, and “set-aside” scenarios are driven by sets of 15 climate scenarios for a reference (1971–2000) and near future (2011–2040) scenario period. Modeling results suggest a large spatial variability of potential impacts across the study areas, due to differences in the projected precipitation trends and the current environmental and socio-economic conditions. While climate change may reduce water and nutrients input to the Ria de Aveiro and Tyligulsyi Liman and increase water inflow to the Vistula Lagoon the socio-economic scenarios and their implications may balance out or reverse these trends. In the intensely managed Mar Menor catchment, climate change has no notable direct impact on water resources, but changes in land use and water management may certainly aggravate the current environmental problems. The great heterogeneity among results does not allow formulating adaptation or mitigation measures at pan-European level, as initially intended by this study. It rather implies the need of a regional approach in coastal zone management. © 2019, The Author(s)

Perceptual uncertainty and action consequences independently affect hand movements in a virtual environment

Supported by Leverhulme Trust Grant RPG-2017-232 awarded to CH and JH. The data are available online from the Open Science Framework: https://osf.io/vskxy/.Peer reviewedPublisher PD