Incentive Contracts in Team Sports - Theory and Practice

A comparison of incentive clauses of players’ contracts in German soccer and clauses used in the NFL and NBA shows considerable differences. Against the background of principle-agent theory we have a closer look at these incentive systems. In contrast to other industries it is easy to observe the employees’ effort in team sports. Therefore, it would be desirable to set incentives for players based on their individual effort. We show that there are reasons why incentive clauses in professional German soccer, the NBA and the NFL are not directly based on effort. We argue that there are two main reasons: Firstly, efficient incentives are complementarily provided by subjective and objective performance measures. Secondly, cooperation amongst team members is essential in team sports.sports, labor contracts, agency theory, incentives,

Was hat die Reform der Minijobs bewirkt?

Viel wird über die "Hartz-Reformen" und ihre Effekte spekuliert, aber es gibt bislang so gut wie keine aussagekräftigen Belege, auf die sich derartige Schlussfolgerungen stützen können. Auch wenn sich viele Wirkungen erst im Zeitablauf richtig entfalten werden, besteht doch die Möglichkeit zu einer ersten Zwischenbilanz für Komponenten, die bereits umgesetzt sind. Eine solche ist die Neuregelung bei Minijobs, die zum 1. April 2003 in Kraft trat. Die Untersuchung beinhaltet damit die erste fundierte Analyse für diesen Bereich. Sie knüpft an das umfassende Evaluierungskonzept an, das als Heft 74 der "RWI : Schriften" veröffentlicht worden war. Untersucht werden insbesondere die Quellen des Zuflusses in Minijobs nach der Reform sowie der Handlungsbedarf, der dadurch entsteht, dass Arbeitslose nicht im erwarteten Umfang derartige Beschäftigungsverhältnisse aufnehmen bzw. aus ihnen heraus in eine sozialversicherungspflichtige Beschäftigung wechseln. Die Ergebnisse liefern ein gemischtes Bild: So wurde das Ziel, die Attraktivität geringfügiger Beschäftigungsverhältnisse zu steigern, zwar erreicht, jedoch sind erhebliche Zweifel angebracht, ob Minijobs für Arbeitslose tatsächlich als Brücke in nicht-geringfügige Beschäftigung dienen können. Um diese Funktion zu stärken, wird der "Erweiterte Minijob für Arbeitslose" vorgestellt, der in bestimmten Fällen eine zeitlich befristete Erhöhung der Einkommensgrenze vorsieht, wobei gleichzeitig die Hinzuverdienstmöglichkeiten generöser gestaltet werden. Zur Abrundung werden die Arbeitsmarktwirkungen sowie die "Kosten" des Reformvorschlags abgeschätzt

Precise ultra fast single qubit control using optimal control pulses

Ultra fast and accurate quantum operations are required in many modern scientific areas - for instance quantum information, quantum metrology and magnetometry. However the accuracy is limited if the Rabi frequency is comparable with the transition frequency due to the breakdown of the rotating wave approximation (RWA). Here we report the experimental implementation of a method based on optimal control theory, which does not suffer these restrictions. We realised the most commonly used quantum gates - the Hadamard (\pi/2 pulse) and NOT (\pi pulse) gates with fidelities ($F^{\mathrm{exp}}_{\pi/2}=0.9472\pm0.01$ and $F^{\mathrm{exp}}_{\pi}=0.993\pm0.016$), in an excellent agreement with the theoretical predictions ($F^{\mathrm{theory}}_{\pi/2}=0.9545$ and $F^{\mathrm{theory}}_{\pi}=0.9986$). Moreover, we demonstrate magnetic resonance experiments both in the rotating and lab frames and we can deliberately "switch" between these two frames. Since our technique is general, it could find a wide application in magnetic resonance, quantum computing, quantum optics and broadband magnetometry.Comment: New, updated version of the manuscript with supplementary informatio

Towards a unified picture of polarization transfer -- pulsed DNP and chemically equivalent PHIP

Nuclear spin hyperpolarization techniques, such as dynamic nuclear polarization (DNP) and parahydrogen-induced polarization (PHIP), have revolutionized nuclear magnetic resonance and magnetic resonance imaging. In these methods, a readily available source of high spin order, either electron spins in DNP or singlet states in hydrogen for PHIP, is brought into close proximity with nuclear spin targets, enabling efficient transfer of spin order under external quantum control. Despite vast disparities in energy scales and interaction mechanisms between electron spins in DNP and nuclear singlet states in PHIP, a pseudo-spin formalism allows us to establish an intriguing equivalence. As a result, the important low-field polarization transfer regime of PHIP can be mapped onto an analogous system equivalent to pulsed-DNP. This establishes a correspondence between key polarization transfer sequences in PHIP and DNP, facilitating the transfer of sequence development concepts. This promises fresh insights and significant cross-pollination between DNP and PHIP polarization sequence developers.Comment: 11+5 pages, 5 figure

Optically induced dynamic nuclear spin polarisation in diamond

The sensitivity of Magnetic Resonance Imaging (MRI) depends strongly on nuclear spin polarisation and, motivated by this observation, dynamical nuclear spin polarisation has recently been applied to enhance MRI protocols (Kurhanewicz, J., et al., Neoplasia 13, 81 (2011)). Nuclear spins associated with the 13 C carbon isotope (nuclear spin I = 1/2) in diamond possess uniquely long spin lattice relaxation times (Reynhardt, E.C. and G.L. High, Prog. in Nuc. Mag. Res. Sp. 38, 37 (2011)) If they are present in diamond nanocrystals, especially when strongly polarised, they form a promising contrast agent for MRI. Current schemes for achieving nuclear polarisation, however, require cryogenic temperatures. Here we demonstrate an efficient scheme that realises optically induced 13 C nuclear spin hyperpolarisation in diamond at room temperature and low ambient magnetic field. Optical pumping of a Nitrogen-Vacancy (NV) centre creates a continuously renewable electron spin polarisation which can be transferred to surrounding 13 C nuclear spins. Importantly for future applications we also realise polarisation protocols that are robust against an unknown misalignment between magnetic field and crystal axis.Comment: This is the revision submitted to NJ

Qudi: a modular python suite for experiment control and data processing

Qudi is a general, modular, multi-operating system suite written in Python 3 for controlling laboratory experiments. It provides a structured environment by separating functionality into hardware abstraction, experiment logic and user interface layers. The core feature set comprises a graphical user interface, live data visualization, distributed execution over networks, rapid prototyping via Jupyter notebooks, configuration management, and data recording. Currently, the included modules are focused on confocal microscopy, quantum optics and quantum information experiments, but an expansion into other fields is possible and encouraged. Qudi is available from https://github.com/Ulm-IQO/qudi and is freely useable under the GNU General Public Licence.Comment: Software paper, 9 pages, 2 figure