University of Paderborn

About: University of Paderborn is a education organization based out in Paderborn, Nordrhein-Westfalen, Germany. It is known for research contribution in the topics: Control reconfiguration & Software. The organization has 6684 authors who have published 16929 publications receiving 323154 citations.

Temperature stabilized surface reconstructions at polar ZnO(0001).

Abstract: The atomic structure of the polar ZnO(0001) surfaces in a dry and humid oxygen environment is studied combining diffraction experiments and density-functional theory. Our results indicate that for similar stoichiometries a large number of very different, but energetically almost degenerate reconstructions exist. Thus vibrational entropy, which could be safely neglected for most semiconductor surfaces becomes dominant, giving rise to a hitherto not reported strong dependence of surface phase diagrams on temperature. Based on this insight we are able to consistently describe and explain the experimentally observed surface structures on polar ZnO(0001) surfaces.

The Returns to Scarce Talent: Footedness and Player Remuneration in European Soccer

Abstract: The authors investigate the salary returns to the ability to play football (soccer) with both feet. The majority of footballers are predominantly right footed. Using two data sets, a cross section of footballers in the five main European leagues and a panel of players in the German Bundesliga, the authors find robust evidence of a substantial salary premium for two-footed ability, even after controlling for available player performance measures. The authors assess how this premium varies across the salary distribution and by player position.

Computing Nash equilibria for scheduling on restricted parallel links

Abstract: We consider the problem of routing n users on m parallel links, under the restriction that each user may only be routed on a link from a certain set of allowed links for the user. Thus, the problem is equivalent to the correspondingly restricted problem of assigning n jobs to m parallel machines. In a pure Nash equilibrium, no user may improve its own individual cost (delay) by unilaterally switching to another link from its set of allowed links. As our main result, we introduce a polynomial time algorithm to compute from any given assignment a pure Nash equilibrium with non-increased makespan. The algorithm gradually changes a given assignment by pushing unsplittable user traffics through a network that is defined by the users and the links. Here, we use ideas from blocking flows. Furthermore, we use similar techniques as in the generic Preflow-Push algorithm to approximate a schedule with minimum makespan, gaining an improved approximation factor of 2 - 1/w1 for identical links, where w1 is the largest user traffic. We extend this result to related links, gaining an approximation factor of 2. Our approximation algorithms run in polynomial time. We close with tight upper bounds on the coordination ratio for pure Nash equilibria.