Substitution Between Managers and Subordinates: Evidence from British Football

We use data on British football managers and teams over the 1994-2007 period to study substitution and complementarity between leaders and subordinates. We find for the Premier League (the highest level of competition) that, other things being equal, managers who themselves played at a higher level raise the productivity of less-skilled teams by more than that of highly skilled teams. This is consistent with the hypothesis that one function of a top manager is to communicate to subordinates the skills needed to succeed, since less skilled players have more to learn. We also find that managers with more accumulated professional managing experience raise the productivity of talented players by more than that of less-talented players. This is consistent with the hypothesis that a further function of successful managers in high-performance workplaces is to manage the egos of elite workers. Such a function is likely more important the more accomplished the workers are -- as indicated, in our data, by teams with greater payrolls.Productivity, leadership

A Scanned Perturbation Technique For Imaging Electromagnetic Standing Wave Patterns of Microwave Cavities

We have developed a method to measure the electric field standing wave distributions in a microwave resonator using a scanned perturbation technique. Fast and reliable solutions to the Helmholtz equation (and to the Schrodinger equation for two dimensional systems) with arbitrarily-shaped boundaries are obtained. We use a pin perturbation to image primarily the microwave electric field amplitude, and we demonstrate the ability to image broken time-reversal symmetry standing wave patterns produced with a magnetized ferrite in the cavity. The whole cavity, including areas very close to the walls, can be imaged using this technique with high spatial resolution over a broad range of frequencies.Comment: To be published in Review of Scientific Instruments,September, 199

Universal and wide shear zones in granular bulk flow

We present experiments on slow granular flows in a modified (split-bottomed) Couette geometry in which wide and tunable shear zones are created away from the sidewalls. For increasing layer heights, the zones grow wider (apparently without bound) and evolve towards the inner cylinder according to a simple, particle-independent scaling law. After rescaling, the velocity profiles across the zones fall onto a universal master curve given by an error function. We study the shear zones also inside the material as function of both their local height and the total layer height.Comment: Minor corrections, accepted for PRL (4 pages, 6 figures