Variabilité génétique de Trypanosoma congolense, agent de la trypanosomose animale : implications taxonomiques et épidémiologiques

#Trypanosoma congolense est une espèce de protozoaire parasite, qui est un des responsables majeurs de la trypanosome animale sévissant en Afrique. Il fait partie du sous-genre #Nannonomas, de la famille des #Trypanosomatidae. Selon la taxonomie actuellement en vigueur il se subdivise en 3 groupes écogéographiques appelés : "Savannah", "Forest", et "Kilifi". Notre travail a eu pour objectif d'étudier la variabilité génétique de ce parasite par électrophorèse multilocus d'isoenzymes et par amplification de manière aléatoire de l'ADN ou Random Amplified Polymorphic DNA (RAPD), et surtout, d'appliquer à l'analyse de ces données les méthodes de la génétique de l'évolution. Nous avons analysé à cet effet 49 stocks d'origines géographiques diverses avec 18 systèmes isoenzymatiques polymorphes et 23 amorces RAPD. Nous avons d'abord commencé par mettre au point un milieu de culture qui permet de maintenir de façon pérenne #T. congolense in vitro. Les résultats obtenus sur les analyses génétiques corroborent la subdivision actuelle de #T. congolense en 3 groupes distincts. Dans l'analyse phylogénétique, #T. congolense n'apparaît pas comme un groupe monophylétique distinct des autres espèces incluses dans notre analyse (#T. simiae, #T. godfreyi). Il est impossible de savoir si ce résultat est dû au fait que le niveau de résolution des isoenzymes et des RAPD est mal adapté pour étudier des niveaux de divergence phylogénétique aussi importants (horloge moléculaire trop rapide), ou si #T. congolense est un groupe réellement polyphylétique. Nous avons comparé la variabilité RAPD de #T. congolense avec celles d'autres parasites voisins (#Trypanosoma brucei sensu lato, agent de la trypanosomose africaine, #T. cruzi, agent de la maladie de Chagas, et diverses espèces de #Leishmania$, agents des leishmanioses). (Résumé d'auteur

The Contribution of Housing to the Dynamics of Inequalities

This paper proposes a unified framework for the analysis of inequalities. In contrast to the former literature on inequalities, housing is included as a major determinant of individual saving behavior. Disparities across locations affect individual outcomes in both labor and education markets. In a Bewley-Huggett-Aiyagari type model where several frictions are represented, the model allows for segmentation between homeowners and renters in the housing market, imperfection in the capital market and residential mobility over the life-cycle. Moreover, individual location is assumed to affect labor productivity, wealth accumulation via the dynamics of housing prices and the human capital acquisition process of the next generation. The dynamics of prices combined to bequest motive provide the perfect framework to understand the tenure choice of individuals. Furthermore, the fixity of housing supply in each neighborhood combined with borrowing constraints prevent some households from living in their preferred area, which leads to segregation. Using this general framework, the paper contributes to the understanding of the complex relationships between labor, housing and education markets. Finally, several experiments aimed at decreasing the level of inequalities at the individual and location level are provided

Criminal Networks and Conflict?resolution Mechanisms in Northern Mali

Northern Mali faces three principle, intertwining security threats: trafficking, rebellious uprisings and terrorist activity. Any attempts at maintaining law and order are undermined by the fragility of state structures. These threats also weaken the socioeconomic fabric of local communities and Malian national and territorial unity. The Malian government endeavours to address these challenges by adopting and implementing security and anti?terrorism policies, as well as social and economic development programmes. External partners support the Malian government in its efforts through a variety of joint anti?terrorism and development policies aiming to strengthen the state's operational capacity in the region. Furthermore, local communities work alongside state actors in the development and securitisation of Northern Mali by employing traditional conflict?management mechanisms (intercommunity and interclan solidarity systems). This strategy may considerably reduce the risk of open conflict and contribute to the establishment of a multilevel shared governance system

Seed value chains for Sorghum and Millet in Mali: A state-based system in transition

"This paper reviews the structure and performance of the sorghum and millet seed sector in Mali. The Sahel is the origin of pearl millet and sorghum, seed selection and management of these crops is embedded in local cultures, and most producers of these crops are subsistence oriented. Despite seed sector reform, no certified seed of these crops is sold in local markets and farmers prefer to rely on themselves or each other for seed. The dominant source of certified seed is the national seed service. Certified seed is multiplied by contracted farmers and seed producer groups, and supplied to farmers through farmers' associations, development organizations, and extension services. The informal sector supplies farmers with non-certified seed directly and indirectly through village grain markets. There is no consensus about whether it is lack of effective demand or supply that constrains farmer use of certified sorghum and millet seed, but researchers generally conclude that the process of certifying seed is too lengthy, some mechanism must be established for production and trade of locally-adapted landraces, and Mali's highly structured farmers' associations could play an even stronger role in testing and promoting demand for certified seed. Recommendations have included the use of small packs and seed auctions where market infrastructure is sparse, and in more commercialized areas, involvement of agro-input dealers, shopkeepers and traders. Still, estimated adoption rates for improved millet (under 10 percent of crop area) and sorghum seed (under 20 percent of crop area) could be as high as can be expected in this challenging natural environment and institutional context." from Author's AbstractSeeds, Formal sector, Informal sector, Millet, Sorghum, Seed markets, Biodiversity,

Health Needs Assessment for the City of Ségou, Mali

In 2007, the Earth Institute at Columbia University selected Ségou, the capital city of Ségou region in Mali, to become one of what were then seven Millennium Cities. This designation has galvanized local and international parties to devise sustainable strategies aimed at reducing poverty and supporting economic development. The city of Ségou is actively working towards achieving the health-related Millennium Development Goals (MDGs) by 2015: reducing child mortality (MDG 4); improving maternal health (MDG 5); and combating HIV/AIDS, malaria and other diseases (MDG 6). This needs assessment finds that Ségou has made progress in achieving these Goals. Noteworthy achievements made by Urban Ségou include: providing free antenatal care to all pregnant women; the successful implementation of an immunization campaign for children; and low HIV prevalence rates, due in part to effective voluntary counseling and testing (VCT) at all health facility levels in Ségou

Robust Facial Features Tracking Using Geometric Constraints and Relaxation

International audienceThis work presents a robust technique for tracking a set of detected points on a human face. Facial features can be manually selected or automatically detected. We present a simple and efficient method for detecting facial features such as eyes and nose in a color face image. We then introduce a tracking method which, by employing geometric constraints based on knowledge about the configuration of facial features, avoid the loss of points caused by error accumulation and tracking drift. Experiments with different sequences and comparison with other tracking algorithms, show that the proposed method gives better results with a comparable processing time

Housing wealth accumulation: The role of public housing

The public housing sector provides housing units at below-market rents, potentially allowing its tenants to save for a downpayment more quickly than they would have otherwise. In this paper, we analyze the effect of a spell in public housing on age at first-time homeownership using the French Housing Survey. We use a pseudo-panel approach that takes into account the specificities of the local housing market, to derive individual tenure transitions from multiple cross-sections data. Using an IV strategy to control for a potential selection into public housing, we jointly estimate public housing tenancy and duration before first-time homeownership, and take into account unobserved heterogeneity. Our results indicate that a spell in public housing increases the hazard to homeownership, supporting the idea that, in France, the public housing policy provides an important pathway to homeownership