Le Tribalisme Comme Idéologie Légitimatrice de la Hiérarchie Sociale dans les Sociétés Composites : une Étude auprès de Jeunes Camerounais

Le tribalisme est l’un des maux dont souffre un grand nombre de sociétés africaines (Messanga & Nzeuta Lontio, 2020). C’est sans doute cette réalité qui pousse les sciences humaines et sociales à en faire un objet de recherche. Pour la psychologie sociale par exemple, l’intérêt pour un tel sujet pourrait se situer dans la perspective d’une mesure de l’impact de ce phénomène social sur les relations intergroupes. Dans cette logique, et dans celle des études qui établissent un lien entre identité ethnique et Orientation de la Dominance Sociale (Ho et al., 2015 ; Levin et al., 1998), la présente étude propose de considérer le tribalisme comme un mythe légitimisateur qui accentue la hiérarchie sociale et, de ce fait, maintient le pouvoir des dominants sur les dominés. Afin d’atteindre cet objectif, la présente étude a recouru à 138 participants de nationalité camerounaise et d’âge variant entre 17 et 32 ans par le biais de l’échantillonnage accidentel. Les résultats obtenus après l’administration de l’échelle d’Orientation de la Dominance Sociale et d’une échelle d’attitude à l’égard du tribalisme révèlent l’existence d’une corrélation positive entre les deux variables (r = .41). Ils apportent ainsi un soutien empirique à la prédiction formulée. Comme contribution théorique, cette étude fournit des données statistiques permettant de répertorier le tribalisme dans la nomenclature des mythes légitimisateurs de la hiérarchie sociale. Tribalism is one of the evils from which many African societies suffer (Messanga & Nzeuta Lontio, 2020). It is undoubtedly this reality which prompts the human and social sciences to make it an object of research. For social psychology, for example, the interest in such a subject could lie in the perspective of measuring the impact of this social phenomenon on intergroup relations. In this logic, and in that of the studies which establish a link between ethnic identity and Orientation of Social Dominance (Ho et al., 2015; Levin et al., 1998), the present study proposes to consider tribalism as a legitimizing myth which accentuates the social hierarchy and, therefore, maintains the power of the dominant over the dominated. In order to achieve this objective, the present study used 138 participants of Cameroonian nationality and of ages varying between 17 and 32 years by means of accidentalsampling. The results obtained after the administration of the Orientation of Social Dominance scale and of an attitude towards tribalism scale reveal the existence of a positive correlation between the two variables (r = .41 ). They thus provide empirical support to the prediction formulated. As a theoretical contribution, this study provides statistical data making it possible to list tribalism in the nomenclature of legitimizing myths of the social hierarchy

Distance-based and Orientation-based Visual Servoing from Three Points

International audienceThis paper is concerned with the use of a spherical-projection model for visual servoing from three points. We propose a new set of six features to control a 6-degree-of-freedom (DOF) robotic system with good decoupling properties. The first part of the set consists of three invariants to camera rotations. These invariants are built using the Cartesian distances between the spherical projections of the three points. The second part of the set corresponds to the angle-axis representation of a rotation matrix measured from the image of two points. Regarding the theoretical comparison with the classical perspective coordinates of points, the new set does not present more singularities. In addition, using the new set inside its nonsingular domain, a classical control law is proven to be optimal for pure rotational motions. The theoretical results and the robustness to points range errors of the new control scheme are validated through simulations and experiments on a 6-DOF robot arm

Seasonal Polyphenism in Bicyclus dorothea (Lepidoptera: Nymphalidae) Across Different Habitats in Cameroon

Many organisms exhibit changes in phenotypic traits as a response to seasonal environmental variation. We investigated the role of habitat in generating seasonal polyphenism in different populations of the light bush brown butterfly Bicyclus dorothea (Cramer, 1779) (Lepidoptera: Nymphalidae) in Cameroon. Butterflies were caught during the wet and dry seasons across four localities representing two distinct habitats, namely forest and ecotone (forest-savanna transition zone) over a 2-yr period (2015-2016). We found distinct variation in the wing pattern characteristics of butterflies in response to seasonality and habitat. Specifically we observed that: 1) all wing characters are not seasonally plastic in B. dorothea; 2) populations from ecotone tend to be more variable, with individuals exhibiting wings with large spots during the wet season and very reduced spots in the dry season while in forest populations, individuals exhibit wings with large spots during the wet season, but in the dry season, spots are not as greatly reduced as their ecotone counterparts; 3) this polyphenism in B. dorothea alternated consistently during the wet and dry seasons over the 2 yr of sampling. Bicyclus species have become a textbook example of seasonal polyphenism while this study extends this model system to the unique forest-ecotone gradient of Central Africa and demonstrates the complexity of seasonal forms in different habitats

Vision-based Control of 2D Plane Poiseuille Flow

International audienceThis paper introduces a new approach for active fluid flows control: the vision-based approach. By using vision, dense flow velocity maps can be estimated and used in an observer-free closed-loop scheme to control a flow. This new approach is validated on a 2D plane Poiseuille flow and is proven to outperform the existing Poiseuille flow control appraches which use a limited number of available shear stress measurements

Commande basée vision d'écoulements fluides

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]SPEE [Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]SPEEColloque avec actes et comité de lecture. Internationale.National audienceCet article propose une nouvelle approche de commande en boucle fermée d'un écoulement fluide. Cette approche permet de s'affranchir de la synthèse d'un observateur. Pour ce faire, un dispositif de visualisation est utilisé, il permet de remonter au champ de vitesses des particules via des techniques de flot optique. Nous montrons très nettement les bénéfices d'utilisation d'une telle approche en présence du bruit de mesures par rapport aux approches classiques utilisant le frottement pariétal. Ces dernières approches sont également surpassées dans le cas d'une mauvaise initialisation de leur observateur nécessaire à la loi de commande

Fluid Flow Control: a Vision-Based Approach

International audienceThis paper proposes a new approach to control a flow. Controlling a flow consists either to change its state to another state or to maintain its current state whatever external disturbances. Here the control of the laminar plane Poiseuille flow is considered. To estimate the state of this flow, existing control methods rely on a set of limited wall shear stress measurements. These existing methods suffer from limited observations, from noisy measurements and from the initialization involved in the observer required to estimate the flow state. To deal with these issues, this paper proposes a vision-based control approach. More precisely, by visualizing a fluid flow, dense flow velocity maps can be computed via optical flow techniques and subsequently used to build an observer-free closed-loop control law. This approach is formally proven to be of great improvements for the control of this flow in comparison with existing control approaches