Contributions in Merlin

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When integrating data from autonomous sources, exact matches of data items that represent the same real-world object often fail due to a lack of common keys. Yet in many cases structural information is available and can be used to match such data. Typically the matching must be approximate since the representations in the sources differ. We propose pq-grams to approximately match hierarchical data from autonomous sources and define the pq-gram distance between ordered labeled trees as an effective and efficient approximation of the fanout weighted tree edit distance. We prove that the pq-gram distance is a lower bound of the fanout weighted tree edit distance and give a normalization of the pq-gram distance for which the triangle inequality holds. Experiments on synthetic and real-world data (residential addresses and XML) confirm the scalability of our approach and show the effectiveness of pq-grams.

This paper presents a model of a professional sports league and analyzes the effect of luxury taxes on competitive balance, club profits, and social welfare. It shows that a luxury tax increases aggregate salary payments in the league and produces a more balanced league. Moreover, a higher tax rate increases the profits of large-market clubs, whereas the profits of small-market clubs only increase if the tax rate is not set inadequately high. Finally, we show that social welfare increases with a luxury tax.

Abstract Previous research on the neural underpinnings of empathy has been limited to affective situations experienced in a similar way by an observer and a target individual. In daily life we also interact with people whose responses to affective stimuli can be very different from our own. How do we understand the affective states of these individuals? We used functional magnetic resonance imaging to assess how participants empathize with the feelings of patients who reacted with no pain to surgical procedures but with pain to a soft touch. Empathy for pain of these patients activated the same areas (insula, medial/anterior cingulate cortex) as empathy for persons who responded to painful stimuli in the same way as the observer. Empathy in a situation that was aversive only for the observer but neutral for the patient recruited areas involved in self-other distinction (dorsomedial prefrontal cortex) and cognitive control (right inferior frontal cortex). In addition, effective connectivity between the latter and areas implicated in affective processing was enhanced. This suggests that inferring the affective state of someone who is not like us can rely upon the same neural structures as empathy for someone who is similar to us. When strong emotional response tendencies exist though, these tendencies have to be overcome by executive functions. Our results demonstrate that the fronto-cortical attention network is crucially involved in this process, corroborating that empathy is a flexible phenomenon which involves both automatic and controlled cognitive mechanisms. Our findings have important implications for the understanding and promotion of empathy, demonstrating that regulation of one's egocentric perspective is crucial for understanding others.

We combine survey data on friendship networks and individual characteristics with experimental observations from dictator games. Dictator offers are primarily explained by social distance - giving follows a simple inverse distance law. While student demographics play a minor role in explaining offer amounts, individual heterogeneity is important for network formation. In particular, we detect significant homophilous behavior - students connect to others similar to them. Moreover, the network data reveal a strong preference for cliques - students connect to those already close. The study is one of the first to identify network architecture with individual behavior in a strategic context.

Video peer to peer streaming and video on demand applications bring new challenges to storing data. Such an application is LiveShift which is currently being developed at the Communication Systems Group of University of Zurich and includes retrieval and long term storage of video data. However it doesn't yet remove data, and in this thesis storage strategies for video streaming and demand in peer to peer environments are compared, and cache replacement policies are selected, modified and extended to work optimal with LiveShift. Changes to LiveShift were made, \emphe.g. introducing the notion of intervals to avoid fragmentation. The thesis should have concluded with selecting a optimal cache algorithms showing the best trade-off between hit/miss-rate and delay, but due to statistical errors the comparison did not show any favorite. Instead the characteristics of the algorithms were confirmed in specifically tailored scenarios showing off specific advantages.

In this thesis, we address a non-invasive sensory feedback system for prosthetic applications. Modern hand prostheses make use of electromyographic (EMG) signals of the remaining hand innervations to control an artificial limb. In contrast to our natural upper limbs, which are sensory-motor coordinated, the communication with a myoelectrically controlled hand prosthesis is only one-directional and consequently no sensory information is fed back to the body. Mainly due to this missing bidirectional information flow, the prosthesis is often not perceived as an integral part of the own body and low user acceptance of prosthesis wearers has been reported. We propose to use transcutaneous electrical stimulation on the lower back to convey pressure as well as proprioceptive feedback regarding the state of a prosthetic hand. For the representation of locally applied force and spatial movements of the hand, we suggest to make use of stationary and moving electrotactile stimulation patterns. We developed a transcutaneous electrical stimulator to investigate to what extent the lower back can be tackled to display sensory feedback. With the developed voltage-controlled device, we performed a series of experiments with 37 volunteer participants. The goal was to assess skin characteristics and basic properties of surface electrical stimulation and to gain insights into the amount of information that could be reliably fed back to the user of a prosthesis. We studied the influence of three different electrode sizes (4.9 cm2, 8 cm2 and 25 cm2) and frequencies (2, 4 and 6 kHz) on the comfort of evoked sensation and on skin characteristics under transcutaneous electrical stimulation. The electrode size and applied frequency did not show a significant effect on perceived stimulation comfort, but on skin impedance, inflowing current, stimulation range, comfort level voltage, current density and power consumption. The applied frequency did not influence the measured parameters to the same extent as electrode size. However, the effect of frequency increased in inverse relation to the size of the electrodes. Larger electrodes showed a reduced skin impedance together with lower required voltages to elicit a sensation and a decreased stimulation range. Furthermore, inter-individual differences were smaller with larger electrodes. Thus, advantages of large electrodes are system stability and low required energy. Drawbacks are the small stimulation range that can be exploited to transmit distinct levels of information and the large covered surface area, which makes stimulation localization more difficult due to a widespread activation area. Consequently, the electrode size represents a trade-off between stability and selectivity and should be determined dependent on the intended application. To gain insights into how much electrotactile information can be reliably recognized on the lower back, we tested the ability of subjects to detect several local and moving stimulation patterns without any previous training. Four electrode pairs were arranged in a rectangular configuration on the lower back and the sensory stimulation was applied either stationary or an up or down traveling sensation between two electrode pairs was induced. We studied the accuracy of sensation detection for two different stimulation waveforms (continuous square pulsed or burst-modulated) and three frequencies (2, 4 and 6 kHz). The mean performance in correctly classifying the applied stimulation patterns was dependent on the stimulation waveform and on the number of simultaneously presented stimuli. The results show an accuracy of unidirectional moving sensation detection of 92% for the best suited stimulation parameters (continuous square pulses). For the best stimulation parameters regarding local stimulation (burst-modulated wave), the mean performance for correct stimulus classification on one electrode pair was 89%. These scores indicate, that local as well as moving sensation patterns can be reliably recognized and the lower back may present a suitable target to display rich and reliable sensory feedback information.

Quantitative prediction of quality properties (i.e. extra-functional properties such as performance, reliability, and cost) of software architectures during design supports a systematic software engineering approach. Designing architectures that exhibit a good trade-off between multiple quality criteria is hard, because even after a functional design has been created, many remaining degrees of freedom in the software architecture span a large, discontinuous design space. In current practice, software architects try to find solutions manually, which is time-consuming, can be error-prone and can lead to suboptimal designs. We propose an automated approach to search the design space for good solutions. Starting with a given initial architectural model, the approach iteratively modifies and evaluates architectural models. Our approach applies a multi-criteria genetic algorithm to software architectures modelled with the Palladio Component Model. It supports quantitative performance, reliability, and cost prediction and can be extended to other quantitative quality criteria of software architectures. We validate the applicability of our approach by applying it to an architecture model of a component-based business information system and analyse its quality criteria trade-offs by automatically investigating more than 1200 alternative design candidates.

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