A Model for the Origin and Properties of Flicker-Induced Geometric Phosphenes

We present a model for flicker phosphenes, the spontaneous appearance of geometric patterns in the visual field when a subject is exposed to diffuse flickering light. We suggest that the phenomenon results from interaction of cortical lateral inhibition with resonant periodic stimuli. We find that the best temporal frequency for eliciting phosphenes is a multiple of intrinsic (damped) oscillatory rhythms in the cortex. We show how both the quantitative and qualitative aspects of the patterns change with frequency of stimulation and provide an explanation for these differences. We use Floquet theory combined with the theory of pattern formation to derive the parameter regimes where the phosphenes occur. We use symmetric bifurcation theory to show why low frequency flicker should produce hexagonal patterns while high frequency produces pinwheels, targets, and spirals

Large-vscale hydrogen production and storage technologies: Current status and future directions

This is an accepted manuscript of an article published by Elsevier in International Journal of Hydrogen Energy on 13/11/2020, available online: https://doi.org/10.1016/j.ijhydene.2020.10.110 The accepted version of the publication may differ from the final published version.Over the past years, hydrogen has been identified as the most promising carrier of clean energy. In a world that aims to replace fossil fuels to mitigate greenhouse emissions and address other environmental concerns, hydrogen generation technologies have become a main player in the energy mix. Since hydrogen is the main working medium in fuel cells and hydrogen-based energy storage systems, integrating these systems with other renewable energy systems is becoming very feasible. For example, the coupling of wind or solar systems hydrogen fuel cells as secondary energy sources is proven to enhance grid stability and secure the reliable energy supply for all times. The current demand for clean energy is unprecedented, and it seems that hydrogen can meet such demand only when produced and stored in large quantities. This paper presents an overview of the main hydrogen production and storage technologies, along with their challenges. They are presented to help identify technologies that have sufficient potential for large-scale energy applications that rely on hydrogen. Producing hydrogen from water and fossil fuels and storing it in underground formations are the best large-scale production and storage technologies. However, the local conditions of a specific region play a key role in determining the most suited production and storage methods, and there might be a need to combine multiple strategies together to allow a significant large-scale production and storage of hydrogen.Published versio

Ein Beitrag zur numerischen Modellierung des Sedimenttransports in Verbindung mit vertikal integrierten Stroemungsmodellen

TIB: RO 2460 (17)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Visual stress in migraine : subjective and psychophysiological responses to intense visual stimulation

This dissertation assesses whether intense visual stimulation can act as a stressor to migraine sufferers between attacks, and whether subjective and psychophysiological reactions to these stimuli can clarify how migraine attacks may be triggered.The first study assessed thresholds of light-induced discomfort and pain in migraine sufferers and non-migrainous controls during a non-headache period. Two instruction sets were compared to assess whether information presented to participants would affect thresholds. The results showed that migraineurs had significantly lower thresholds for light-induced pain. However, this effect was most apparent in those who had heard the negatively biased instructions reinforcing the need to control contextual factors when assessing subjective phenomena such as visual discomfort.The second study assessed subjective and psychophysiological responses of female migraine sufferers and female controls during exposure to visual stimuli incorporating spatial and temporal characteristics that are most likely to be bothersome to migraineurs. Two control stimuli were included to assess responses during similar, but theoretically less aversive conditions. Migraine sufferers had higher heart rate and more frequent electrodermal responses than controls at all points of the study, including baseline and recovery. However, while migraineurs reported higher anxiety during the intense conditions, and reported more visual and somatic complaints than controls during various viewing conditions, they did not show heart rate, heart rate variability or electrodermal changes that would suggest clear changes in autonomic function in response to aversive visual stimulation.The third study assessed ambulatory electrocardiograms to investigate whether autonomic changes would be evident in the period leading up to, during or following a migraine. Three individuals were assessed on a day when they experienced a naturally occurring headache, and on a day when they were not. No obvious pattern of autonomic change was detected before or after headache, although there was some evidence that a pattern of increased heart rate and decreased vagal tone may accompany headache.In summary, the results confirm that migraine sufferers are more sensitive to intense visual stimulation than controls, but do not support the contention that exposure results in widespread autonomic changes. Since interictal visual discomfort is a common in migraine, further research is needed to clarify how it can be incorporated into models of migraine pathophysiology

Die Beweislast bei Markenrechtsverletzungen in Deutschland und in Norwegen unter besonderer Berücksichtigung der Richtlinie 2008/95/EG

Softcover, 17x24Kern der vorliegenden Arbeit ist die praktisch bedeutsame Frage der Beweislastverteilung im deutschen und im norwegischen Markenrecht. Besonders relevant wird dieser Vergleich dadurch, dass das Markenrecht Deutschlands und Norwegens nicht bezugslos nebeneinander stehen, sondern durch die Richtlinie 2008/95/EG (Markenrechtsrichtlinie) und deren Übernahme in das EWR-Abkommen europäisch harmonisiert werden. Vor diesem Hintergrund widmet sich die Arbeit sowohl dem nationalen Recht der beiden Länder, als auch den europäischen Herausforderungen. Zudem wird der Frage nachgegangen, welche Bedeutung dem Beweismaß in diesem Zusammenhang zukommt. Zuletzt geht der Verfasser noch auf die Frage ein, inwieweit sich die Ergebnisse dieser Arbeit auf andere Richtlinien im Bereiche des gewerblichen Rechtsschutzes übertragen lassen