Can we manage first impressions in cooperation problems? An experiment

We study how cooperative behavior reacts to selective (favorable or unfavorable) pre-play information about the cooperativeness of other, unrelated groups within an experimental framework that is sufficiently rich for conflicting behavioral norms to emerge. We find that cooperation crucially depends on pre-play information, coinciding with a change in initial beliefs. Over time, behavior within both types of groups becomes increasingly homogeneous, indicating the formation of two rather different social norms, depending on whether pre-play information was favorable or unfavorable. In addition, we find unfavorable information to substantially reduce the effectiveness of peer punishment. For these differences to emerge it is immaterial whether each member or only one member of a four-person group receives the pre-play information.experiment, information, Norms, cooperation, Effectiveness of Sanctions, Expectations

Effect of local anisotropy on fatigue crack initiation in a coarse grained nickel-base superalloy

In the present work, theoretical approaches, based on grain orientation dependent Young's modulus and Schmid factor are used to describe the influence of local grain orientation on crack initiation behaviour of the coarse grained nickel base superalloy Ren\'e80. Especially for strongly anisotropic crystal structures with large grain size, such as the investigated material, the local elastic properties must be taken into account for assessment of fatigue crack initiation. With an extension of Schmid's law, the resulting shear stress amplitude, which triggers local cyclic plastic deformation, can be calculated depending on local Young's modulus and Schmid factor. A Monte Carlo simulation with 100,000 samples shows how random grain orientation affects these parameters. Furthermore, the product of Young's modulus and Schmid factor (called $E\cdot m$) is used as a parameter to determine how grain orientation influences resulting shear stress amplitude for given total strain amplitude. In addition to the theoretical work using that approach, this model is also validated using isothermal LCF experiments by determining local grain orientation influence on the crack initiation site using SEM-EBSD analyses.Comment: 8 pages, 8 figure

On Probation. An Experimental Analysis

Does probation pay a double dividend? Society saves the cost of incarceration, and convicts preserve their liberty. But does probation also reduce the risk of recidivism? In a meta-study we show that the field evidence is inconclusive. Moreover it struggles with an identification problem: those put on probation are less likely to recidivate in the first place. We therefore complement the field evidence by a lab experiment that isolates the definitional feature of probation: the first sanction is conditional on being sanctioned again during the probation period. We find that probationers contribute less to a joint project; punishment cost is higher; efficiency is lower; inequity is higher. While experimental subjects are on probation, they increase their contributions to a joint project. However, once the probation period expires, they reduce their contributions. While in the aggregate these two effects almost cancel out, critically those not punished themselves do trust the institution less if punishment does not become effective immediately.probation, recidivism, public goods, punishment, experimental economics

Wissen zur Leitidee "Funktionaler Zusammenhang"

Das mathematische Beschreiben funktionaler Zusammenhänge und deren Nutzung beim Problemlösen und Modellieren sind mit Begriffswissenskomponenten wie Wissen zum Zuordnungs- und Kovariationsaspekt verknüpft. Hierbei stellt sich die Frage, wie Wissensniveaus in diesem Bereich beschrieben werden können. In einer empirischen Studie mit über 200 Realschülerinnen und Realschülern der 9. Klasse konnten drei hierarchisch gestufte Niveaus bezüglich des Arbeitens mit Funktionen beobachtet werden

Nature of the volcano transition in the fully disordered Kuramoto model

Randomly coupled phase oscillators may synchronize into disordered patterns of collective motion. We analyze this transition in a large, fully connected Kuramoto model with symmetric but otherwise independent random interactions. Using the dynamical cavity method we reduce the dynamics to a stochastic single oscillator problem with self-consistent correlation and response functions that we study analytically and numerically. We clarify the nature of the volcano transition and elucidate its relation to the existence of an oscillator glass phase