L'agressivité est un comportement fréquemment observé chez les animaux et qui est notamment modulé par la sérotonine (5-HT) et les hormones stéroïdes. Cependant, même si des hypothèses évoquent une interaction possible entre ces molécules dans la régulation des comportements agressifs, peu d’études permettent de les confirmer. De plus les mécanismes neuronaux sous-tendant ces comportements agressifs sont encore peu connus. En utilisant comme modèle l'écrevisse de Louisiane, très étudiée pour son comportement agressif et ses hiérarchies sociales, ce travail montre comment la 5-HT et les hormones stéroïdes modifient les réseaux neuronaux et contrôlent ainsi l'agressivité de ces animaux. La mue des écrevisses est contrôlée par une hormone stéroïde appelée 20-hydroxyecdysone (20E), dont la concentration augmente pendant la prémue. Durant cette période, la 20E diminue à la fois l’agressivité des écrevisses et la locomotion. L’activité du réseau locomoteur, un des supports essentiels de l'agressivité (permettant les approches, les attaques… ou les fuites) et son intégration sensori-motrice sont fortement inhibés également. Cette inhibition passe par une réduction de la réactivité des réseaux, notamment via la baisse de résistance d’entrée (Rin) des motoneurones. En présence de 20E, la concentration de 5-HT augmente fortement dans l’organisme par l’inhibition présumée de la voie de dégradation de la 5-HT. Nous supposons comme déjà décrit sur d’autres réseaux que cette augmentation bloquerait les réseaux dans un état inhibée. Cet état inhibée serait maintenu par la baisse de Rin, causée par la libération de 5-HT sur la partie périphérique des MN principalement inhibitrice. / In animal kingdom, aggressivity is a very frequent behavior obvious. Serotonin (5-HT) and steroid hormones modulate this behavior. However, even if several hypothesis raise that one interaction is possible between these molecules to control aggressivity, no study can confirm it. Moreover, neuronal actions behind this behavior stay unclear. In this study, we show how 5-HT and steroid hormones can regulate neural networks and aggressivity. Crayfish molting is regulated by a steroid hormone, called 20-hydroxyecdysone (20E) and its concentration increases during pre-molt period. 20E decreases crayfish aggressivity and locomotion. Locomotors activities and sensory-motor integration are also inhibited during pre-molt. This inhibition is caused by a drop of neural reactivity because input resistance of motoneurons decreases. After injection of 20E or during pre-molt period, 5-HT concentration increase. We think this increase would block networks in inhibition state during pre-molt.

Title: Problematics of motivation and aggressivity in sports Objectives: Main target of my diploma thesis is to test selfdetermination of individuals participating in sports, their motivations and motivation factors which are connected to aggressivity, by using the questionnaire method. Methods: Datas for research were collected from quantitativ questionaire, which was a compilation of three standard questinnaires, their Czech version used in psychology. A questionnaire called Sport motivation scale - 6 was used to measure selfdetermination, a questionnaire called Percetion of Success Questionaire was used to measure the motivational orientation and a questionnaire called The Buss - Perry Aggression Questionaire was used to measure different dimensions of aggressivity. Results: Results of selfdetermination measured on sportsmen of UK FTVS prove the general hypothesis of high contribution of intrinsic motivation and very low participation of amotivation for any individuals participating in sports. Higherst values measured we got for integrated regulation, which is the most intrinsic form of external motivation. Results of motivational orientation of respondents show clearly dominance of motivational orientation toward the target rather than toward ego. The highest measured value of different forms...

La violence est un phénomène fréquent dans les prisons. D'après la théorie générale de la tension (Agnew, 1992, 2002), l'agressivité (Blevins et al., 2010) ou le suicide (Zhang et al., 2008) seraient le fruit de tensions éprouvées par les détenus. Notre recherche s'appuie sur le modèle d'Agnew pour créer et tester une échelle standardisée appliquée aux détenus. Les analyses en composantes principales et confirmatoires montrent des résultats satisfaisants, avec des indices de cohérence interne significatifs. Notre échelle est donc une première ébauche pour mesurer la tension en détention. Nos résultats montrent que les comportements agressifs et suicidaires peuvent être prédits de façon significative par la mesure de la tension. Toutefois, la tension en tant que variable indépendante et les stratégies de régulation émotionnelle et/ou de coping comme variables médiatrices ne permettent pas de mettre en évidence des modèles significatifs. Cela signifie que la tension doit être appréhendée comme une variable proximale. De même, nous testons les effets modérateurs des variables personnelles et judiciaires. Nos analyses infirment l'effet modérateur supposé des facteurs personnels et situationnels, même si la dépression et le stress ont un effet significatif. Enfin, nos analyses de médiations modérées ne sont pas significatives, que ce soit pour les comportements agressifs ou suicidaires. Pour conclure, la tension serait la variable la plus proximale pour prédire la violence en prison, alors que la régulation émotionnelle ou les stratégies de coping auraient un effet plus distal. Comme les variables modératrices n'ont pas d'effet significatif, nous proposons de les considérer comme des formes implicites de tension. La théorie de la tension appliquée aux détenus est un modèle prometteur mais récent, qui n'a pas été testé empiriquement. Ainsi, au travers de cette recherche, nous avons essayé de mesurer la tension, afin de tester ce modèle et d'identifier ses limites. / Violence is common and frequent in most prisons. According to the general strain theory (Agnew, 1992, 2002), aggression (Blevins et al., 2010) or suicidality (Zhang et al., 2008) are caused by strains experienced by inmates. Our study intends to rely on Agnew's general strain theory in order to create and test a standardized scale applied to inmates, since no psychometric instrument evaluating Agnew's model exists. Principal component analyses and confirmatory analyses applied to our psychometric data show satisfying results, with significant internal consistency indices. Our scale is thus a first attempt to measure strain for inmates. In a second step, this research aims at understanding the effect of strains on inmates' violent behaviors. Our results show that aggressive and suicidal behaviors can significantly be predicted by the strain measure. The strains due to daily-life in jail have a direct effect (indirect for Agnew) on inmates' externalizing violent outcomes. Then, we test the mediating effects of coping skills and emotion regulation strategies. The model depicted by our analyses is not fully consistent with the general strain theory. Analyses considering strain as an independant variable and coping skills and emotion regulation strategies as mediating variables are not significant. This implies that strain measure could be seen as a proximal variable. This conclusion does not totally support Agnew's model, which considers strain as a distal variable. In a next step, we test the moderating effects of personal and judicial variables. Our analyzes invalidate the supposed moderating effect of such factors, even if depression and stress are significant moderating variables. Finally, our moderated mediating analyses are not significant, whether on aggressive or suicidal behaviors. As a conclusion, according to our results, strain would be a proximal variable to predict violence in prison, whereas emotion regulation or coping strategies would be more distal. As the moderating variables are not significant, we suggest to consider them as indirect forms of strains. The general strain theory, especially applied to inmates, is a promising but recent model which has not been empirically tested. Therefore, through this research, we tried to measure strain, in order to test this model and identify its limits.

As vehicle technologies continue to improve it is becoming more evident one of the last major factors impacting fuel economy left today is the driver. In this study the driver is defined as the operator of a vehicle and the difference between driving styles of the driver and vehicle is defined as aggressivity. Driver aggressivity is proven to have a substantial impact on fuel economy in many studies. Many fuel economy tests have been created, all to measure the fuel efficiency of today's vehicles and their related technologies. These tests typically require that the drivers be trained or experienced in fuel economy testing unless the impact of the driver on fuel economy is the variable being tested. It is also recommended, for certain tests, that the driver stay with the same vehicle for the tests entirety. Although these are the requirements, having the same trained drivers for the entirety of a fuel economy test may not always be a viable option. This leads to the question of, what impact can a set of drivers, who are asked to drive the same, have on fuel consumption during a fuel consumption test? The SAE J1321 Type II Fuel Consumption Test Procedure was followed on two identical trucks with two drivers that were untrained in fuel economy testing in order to answer this question. It was found in this particular study that the driver variability can impose up to a 10% fuel economy difference on shorter distance routes where the driver is kept the same. By increasing the distance of the route and swapping drivers variability in fuel economy reduced to 5%. It was shown by this particular test that the impact of the driver when asked to drive the same is minimal compared to real world results of up to 30%. A larger data set and more testing is still necessary to completely understand and validate the impact of the driver on fuel economy testing.

As competições esportivas promovem ambientes de disputas que podem afetar os indivíduos participantes, influenciando o seu comportamento e liberação hormonal. A testosterona influenciada pela competição pode fazer com que haja o aparecimento de comportamentos agressivos nos indivíduos participantes. Nesse estudo tivemos como objetivo, analisar como os níveis de testosterona salivar, agressividade e impulsividade afetam atletas adolescentes de futebol durante uma atividade competitiva. O estudo teve como amostra atletas adolescentes, do sexo masculino, com idades de 14 a 17 anos, nascidos entre os anos 2000 e 2002, num total de 72 de atletas participantes. Os nossos resultados mostraram que a competição influencia os níveis de testosterona (pg/ml), havendo um aumento médio da coleta pré-competição (107,10 ±136,54) para a pós-competição (275,59 ±358,98) sendo um resultado estatístico positivamente significativo (p<0,002), mas não foi possível correlacionar com os resultados comportamentais, obtidos através dos testes de impulsividade (Barratt-youth) e agressividade (STAXI). O comportamento pôde ser relacionado com o resultado final obtidos, tendo os perdedores resultados estatísticos, positivamente significativos para comportamentos de impulsividade motora (p<0,032), agressividade total (p<0,010) e expressão da agressividade (p<0,044). Atletas que marcaram gols possuem uma correlação estatística positivamente significativa com a testosterona coletada antes da competição (p<0,05). Como conclusão a competição influencia tanto o comportamento quanto a modulação da testosterona, podendo o comportamento ser correlacionado com o desempenho dos atletas e a testosterona com os gols marcados. / Sports competitions promote disputes environments that can affect participating individuals, influencing their behavior and hormonal release. In this case, the testosterone hormone, influenced by the competition may lead to the appearance of aggressive behavior in the individuals. In this study, we aimed to analyze how testosterone levels, aggressiveness, and impulsivity affect adolescent soccer athletes during a competitive activity. The study had as sample adolescents, aged 14 to 17 years, born between 2000 and 2002, in a total of 72 athletes. Our results showed that competition influences testosterone levels (pg/ml), with an average increase of pre-competition collection (107,10 ±136,54) for post-competition (275,59 ±358,98), being statistically positive significant outcome, but it was not possible to correlate with the behavioral results obtained through the tests of impulsiveness (Barratt-youth) and aggressiveness (STAXI). The behavior can be related with the final result, where the losers having statistically positive significant outcomes for motor impulsivity behaviors (p<0,032), total aggressiveness (p<0,010) and expression of aggressiveness (p<0,044). The athletes who scored goals have a statistically positive significant correlation with testosterone collected before the competition (p<0,05). As the conclusion, the competition influenced both behaviors then the testosterone modulation and also the behavior can be correlated with the athlete's performance and the testosterone with the goals scored.

La popularité des jeunes à l’adolescence est reconnue comme étant associée à l’augmentation des conduites agressives à travers le temps. Par contre, peu d’études s’intéressent aux mécanismes permettant d’expliquer ce lien. La présente étude vise à évaluer dans quelle mesure les caractéristiques des amis (i.e., niveaux moyens de popularité et d’agressivité) peuvent jouer un rôle médiateur et permettent d’expliquer la relation entre la popularité et le développement de l’agressivité au début du secondaire. Cette étude longitudinale a été menée auprès de 621 élèves de première et deuxième secondaires provenant de trois écoles secondaires publiques situées dans des milieux socio-économiques défavorisés de la région de Montréal. À trois reprises sur une période d’un an, la popularité perçue et l’agressivité des participants ont été évaluées à partir d’une procédure de nominations par les pairs. De la même façon, l’identité et les caractéristiques des amis ont été évaluées de manière répétée. Les résultats montrent que la popularité perçue en secondaire 1 favorise l’affiliation avec des amis qui sont de plus en plus populaires et agressifs au début du secondaire 2. En retour, l’établissement de relation d’amitié avec des amis agressifs permet d’expliquer l’augmentation des conduites agressives à travers le temps. Aussi bien chez les filles que chez les garçons, l’association entre la popularité perçue et la manifestation ultérieure de comportements agressifs s’explique ainsi par les caractéristiques des amis. La discussion porte sur l’importance du contexte relationnel lorsqu’il s’agit de rendre compte des conséquences développementales associées au fait d’être perçu comme étant populaire au début de l’adolescence. / Teenagers’ popularity is known to be linked to an increase in aggressive behaviors through time. However, few studies have explored the mechanisms that can explain this association. This study aims to assess to which extent friends’ popularity and aggressivity can possibly play a mediating role to explain the relationship between popularity and aggressivity at the beginning of high school. The sample of this longitudinal study consists of 621 students in 7th and 8th grade from disadvantaged socio-economic backgrounds who attended three public high schools in the Montreal area. The participants’ popularity and aggressivity scores were measured using a peer nominated protocol and assessed three times over a period of one year. Friends’ identity and characteristics were also measured repeatedly using the same procedure. Results show that participants’ popularity in the beginning of 7th grade promotes friendships with peers who are more and more popular and aggressive at the beginning of 8th grade. In return, friendships with aggressive peers can explain the increase in aggressive conducts at the end of 8th grade. The association between perceived popularity and aggressivity, for both boys and girls, can be explained by friends’ characteristics. The discussion focuses on the importance of the relational context when it comes to accounting for the developmental consequences associated with being perceived as popular in early adolescence.

A playback experiment in which a recording of vocalization is played to the tested subject and its response is observed, is a widely used tool for examining bird song and its functions. Most often only acoustic stimulus is used, but sometimes a visual stimulus is also provided in the form of a dummy. Taxidermic mounts or models made from different materials are used as the dummy. It is discussed among researchers, whether it is or is not necessary to use a dummy in experiments and how does its presence affect behavior of the tested individuals. However, only few studies directly focus on this issue and test the effect of dummies. The best way to test the effects of a dummy on passerines in playback experiments is to test the same individuals in both situations (with a dummy and without a dummy) and compare the reactions. The aim of this theses was to perform such experiments on Chiffchaff (Phylloscopus collybita) and Yellowhammer (Emberiza citrinella) males and to find out whether they would behave similarly in both variants of the experiment, or if their reaction would be enhanced in the presence of a dummy. Chiffchaffs reacted significantly more aggressively in the dummy experiment. The biggest difference was time spent by attacking the dummy and staying close to it. In Yellowhammers, the dummy...