Selection methods regulate evolution of cooperation in digital evolution.

A key, yet often neglected, component of digital evolution and evolutionary models is the 'selection method' which assigns fitness (number of offspring) to individuals based on their performance scores (efficiency in performing tasks). Here, we study with formal analysis and numerical experiments the evolution of cooperation under the five most common selection methods (proportionate, rank, truncation-proportionate, truncation-uniform and tournament). We consider related individuals engaging in a Prisoner's Dilemma game where individuals can either cooperate or defect. A cooperator pays a cost, whereas its partner receives a benefit, which affect their performance scores. These performance scores are translated into fitness by one of the five selection methods. We show that cooperation is positively associated with the relatedness between individuals under all selection methods. By contrast, the change in the performance benefit of cooperation affects the populations' average level of cooperation only under the proportionate methods. We also demonstrate that the truncation and tournament methods may introduce negative frequency-dependence and lead to the evolution of polymorphic populations. Using the example of the evolution of cooperation, we show that the choice of selection method, though it is often marginalized, can considerably affect the evolutionary dynamics.

The UEFA EURO 2012 anti-doping programme - scientific review

The final tournament of the UEFA European Football Championship is one of the top sporting events in the world, and a high-profile event of this kind requires a well-planned and well-executed anti-doping programme to ensure the integrity of results in the competition. UEFA EURO 2012 presented a unique logistical challenge, with the tournament spread across two countries, both covering a large geographical area. This paper discusses the planning and delivery of both the pre tournament out-of-competition (OOC) testing programme and the in-competition (IC) programme, as well as reviewing the activities of doping control officers (DCOs), the whereabouts programme and assessing the sample collection and transport process. The analytical approach applied is also discussed, along with an overview of the distribution of T/E ratios and blood parameters.

Physical determinants of tennis performance in competitive teenage players

It is unclear how physical attributes influence tennis-specific performance in teenage players. The aims of this study were (a) to examine the relationships between speed, explosive power, leg stiffness, and muscular strength of upper and lower limbs; and (b) to determine to what extent these physical qualities relate to tournament play performance in a group of competitive teenage tennis players. A total of 12 male players aged 13.6 +/- 1.4 years performed a series of physical tests: a 5-m, 10-m, and 20-m sprint; squat jump (SJ); countermovement jump (CMJ); drop jump (DJ); multi-rebound jumps; maximum voluntary contraction of isometric grip strength; and plantar flexor of the dominant and nondominant side. Speed (r = 0.69, 0.63, and 0.74 for 5-, 10-, and 20-m sprints, respectively), vertical power abilities (r = -0.71, -0.80 and -0.66 for SJ, CMJ, and DJ, respectively), and maximal strength in the dominant side (r = -0.67 and -0.73 for handgrip and plantar flexor, respectively) were significantly correlated with tennis performance. However, strength in the nondominant side (r = -0.29 and -0.42 for handgrip and plantar flexor) and leg stiffness (r = -0.15) were not correlated with the performance ranking of the players. It seems that physical attributes have a strong influence on tennis performance in this age group and that an important asymmetry is already observed. By monitoring regularly such physical abilities during puberty, the conditioning coach can modify a program to compensate for the imbalances. This would in turn minimize the risks of injuries during this critical period.

Positive Self-Image in Tournaments

This article analyzes the implications of worker overestimation of productivity for firms in which incentives take the form of tournaments. Each worker overestimates his productivity but is aware of the bias in his opponent's self-assessment. The manager of the firm, on the other hand, correctly assesses workers' productivities and self-beliefs when setting tournament prizes. The article shows that, under a variety of circumstances, firms can benefit from worker positive self-image. The article also shows that worker positive self-image can improve welfare in tournaments. In contrast, workers' utility declines due to their own misguided choices.