Entering into,staying, and being active in a group of football supporters: a procedural analysis of engagement. The case of supporters of a French football club

In football (or soccer) stadiums, one of the ends (virages in French, or curve in Italian) brings together the most organized and ardent fans who support their team manu et voce. This article aims to define the dynamics leading individuals to become a part of a group of supporters, an engagement conceived of according to a sequential process. Through a qualitative inquiry, results show the importance of the relational networks in the process of engagement in this type of organization. Moreover, friendly interaction and the levels of sociability encountered over the course of action as part of supporting make up as much incentive to activism as may be understood in the condition of being set back in the general framework of the supporters' careers. The article ends with a discussion on the use of the sociology of collective action and mobilization in order to study the world of football supporters.     

Mechanism Design With Ambiguous Communication Devices

This paper considers mechanism design problems in environments with ambiguity‐sensitive individuals. The novel idea is to introduce ambiguity in mechanisms so as to exploit the ambiguity sensitivity of individuals. Deliberate engineering of ambiguity, through ambiguous mediated communication, can allow (partial) implementation of social choice functions that are not incentive compatible with respect to prior beliefs. We provide a complete characterization of social choice functions partially implementable by ambiguous mechanisms.     

Smoothed Extreme Value Estimators of Non-Uniform Point Processes Boundaries with Application to Star-Shaped Supports Estimation

We address the problem of estimating the edge of a bounded set in ? ^d given a random set of points drawn from the interior. Our method is based on a transformation of estimators dedicated to uniform point processes and obtained by smoothing some of its bias corrected extreme points. An application to the estimation of star-shaped supports is presented.     

Temporal dynamics of inter-limb coordination in ice climbing revealed through change-point analysis of the geodesic mean of circular data

This study examined the temporal dynamics of the inter-limb angles of skilled and less skilled ice climbers to determine how they explored ice fall properties to adapt their coordination patterns during performance. We observed two circular time series corresponding to the upper- and lower-limbs of seven expert and eight inexperienced ice climbers. We analyzed these data through a multiple change-point analysis of the geodesic (or Fréchet) mean on the circle. Guided by the nature of the geodesic mean obtained by an optimization procedure, we extended the filtered derivative method, known to be computationally very cheap and fast, to circular data. Local estimation of the variability was assessed through the number of change-points computed via the filtered derivatives with p-value method for the time series and integrated squared error (ISE). Results of this change-point analysis did not reveal significant differences of the number of change-points between groups but indicated higher ISE that supported the existence of plateaux for beginners. These results emphasized higher local variability of limb angles for experts than for beginners suggesting greater dependence on the properties of the performance environment and adaptive behaviors in the former. Conversely, the lower local variance of limb angles assessed in beginners may reflect their independence of the environmental constraints, as they focused mainly on controlling body equilibrium.