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Abstract: According to flow visualizations performed in water tunnel and referring to a simple phenomenological model describing the nature of exchanges occurring within a two-dimensional mixing layer, a model was built up to specify the nature of flows ensuring the recirculating zone equilibrium over the upper surface of a delta wing at high angle of attack. Perturbing the flows equilibrium leads to delay the vortex breakdown. To cite this article: O. Rodriguez, J. Pruvost, C. R. Mecanique 333 (2005). [Copyright &y& Elsevier]

The structure of the vortex asymetry around a circular cone at high incidence and Reynolds numbers of order 104, is related to the existence of at least four vortices shed from the apex and exhibiting vortex breakdown points correlated with the sign of the lateral force. Control of the lateral force by injection points out three regimes, and not two as usually admitted, corresponding to inversions of the lateral force direction. To cite this article: O. Rodriguez, J. Pruvost, C. R. Mecanique 332 (2004). [Copyright &y& Elsevier]

Since the end of the 1980s, `youth risky behaviours' have become a major issue for public health. The relationship between these behaviours and sporting activity is well-documented but still controversial. This article examines some sociological hypotheses related to this relationship, with data from a pilot survey conducted on a sample of 458 elite-student-athletes (ESAs) aged 16-24, gathered and trained in specialized public centres. We found a significant relationship between motives to do sport and `risky behaviours': ESAs who considered sport as a convivial leisure were more prone to use cannabis, while ESAs who mingled sporting and extra-sporting achievements together were more likely to engage in risky behaviours on the road, possibly because they transposed values from the sporting field (speed, competition) into the `real world'. Moreover, sporting activity may provide opportunities for drug use with peers as well as incentives to use drugs in order to cope with the anxiety induced by high-level competition. Thus `recreational' drugs may be used as `integrative' drugs. [ABSTRACT FROM AUTHOR]

ABSTRACT Aims To study the relationship between sporting activity and alcohol, cigarette and cannabis use among adolescents and young adults, by focusing on elite student athletes (ESAs). Design, setting, subjects Cross-sectional survey (Spring 2002), in a sample of 460 ESAs (ages 16–24 years) recruited at 40 public centres gathering the young sporting elite from 30 different sports in South-Eastern France, comparison with samples of the general population of adolescents in South-Eastern France. Measures Respondents were asked confidentially by a self-administered questionnaire about their use of licit and illicit drugs, their sporting activity and other aspects of their life-style. Findings Prevalences of cigarette, alcohol and cannabis use were markedly lower for ESAs than for other adolescents (generally twice or three times as low). Among ESAs, when compared with the practice of an individual sport, the practice of a team sport was correlated positively with alcohol use (OR = 2.7 for girls, OR = 1.8 for boys), and the practice of a sliding sport was correlated positively with cannabis use (for girls: OR = 2.3) and with alcohol use (for boys: 4.3). Girls who entered competition at international level were more prone to smoke cigarettes and cannabis (OR = 6.1 and 2.4, respectively). Conclusions As a whole, practising sports as an elite student-athlete can be considered as correlated negatively with cigarette, alcohol and cannabis use. Nevertheless, this relationship depends on the kind of sport practised as well as the level of competition, and further research is needed to understand specific elite athletes’ motives for use. [ABSTRACT FROM AUTHOR]