Les champs commerciaux sénégalais à Paris : Coprésences, luttes pour l’espace et stratégies commerciales au sein d’espaces urbains interstitiels

Les chercheurs abordent le plus souvent les activités commerciales des Sénégalais en termes de commerce ethnique, de réseaux commerciaux mourides ou de réseaux transnationaux, en mettant l’accent sur les liens de solidarité des immigrés entrepreneurs. Le concept de champ commercial, auquel nous donnons une dimension spatiale, constitue l’outil descriptif de cet article. Il permet de tenir compte des luttes pour l’occupation de l’espace, des hiérarchies et des concurrences, que les problématiques sur l’ethnic business, la « mouridologie » et les perspectives transnationales ne mettent pas au centre de leurs analyses. Par le biais de cet outil, nous voulons démontrer l’existence de territoires et de lieux commerciaux interstitiels où ne pratique pas qui veut. Au sein de ces espaces, l’ethnique et l’appartenance confrérique ne constituent que des ressources parmi tant d’autres, mobilisées par les acteurs en fonction de leurs capitaux spatiaux, relationnels et économiques.Senegalese immigrants’ enterprises are often analyzed as ethnic businesses, mourid brotherhood networks or transnational networks. Researchers who take these approaches focus on cultural resources or solidarity among ethnic groups. In this paper, the central concept is that of “trade field”, which I look at in spatial terms. This notion allows us to take into account struggles to occupy space, hierarchy, competition and other issues that are not addressed in analyses focused on “ethnic business”, “mouridology” and transnational perspectives. With this conceptual tool, I seek to demonstrate the existence of territories and interstitial commerce that are not open to all comers. In these spaces, ethnic and brotherhood affiliations are but several of the resources that are mobilized by actors according to their spatial, relational and economic capital

African economy and land policy

Thandika Mkandawire reminded us during the 13th CODESRIA GA that land and the agrarian question were present in some way in all the nationalist movements, and liberation struggles the Mau Mau in Kenya, the FLN’s struggles in Algeria, the PAIGC in Guinea Bissau, other struggles in Zimbabwe, South Africa, etc. We know that apartheid South Africa was the story of dispossession—(Pheko)—the reversemovement in South Africa—re-distribution—is extremely slow. So, land has been a very strategic issue, and it is still a very strategic issue. There is currently what some have called a “grain rush”, as “wealthy, foodimporting countries and private investors are acquiring farmland overseas” (Michael Kugelman, 2010:1); something similar to what used to be called the “gold rush”. This is a phenomenon that one finds all across the global South, but Africa is where much of the rush is heading towards, which makes some people talk about a new “scramble “ for Africa—adding on to the struggle over mineral, FOREST, AND MARINE RESOURCES

ScarGAN: Chained Generative Adversarial Networks to Simulate Pathological Tissue on Cardiovascular MR Scans

Medical images with specific pathologies are scarce, but a large amount of data is usually required for a deep convolutional neural network (DCNN) to achieve good accuracy. We consider the problem of segmenting the left ventricular (LV) myocardium on late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) scans of which only some of the scans have scar tissue. We propose ScarGAN to simulate scar tissue on healthy myocardium using chained generative adversarial networks (GAN). Our novel approach factorizes the simulation process into 3 steps: 1) a mask generator to simulate the shape of the scar tissue; 2) a domain-specific heuristic to produce the initial simulated scar tissue from the simulated shape; 3) a refining generator to add details to the simulated scar tissue. Unlike other approaches that generate samples from scratch, we simulate scar tissue on normal scans resulting in highly realistic samples. We show that experienced radiologists are unable to distinguish between real and simulated scar tissue. Training a U-Net with additional scans with scar tissue simulated by ScarGAN increases the percentage of scar pixels correctly included in LV myocardium prediction from 75.9% to 80.5%.Comment: 12 pages, 5 figures. To appear in MICCAI DLMIA 201

Policies to favour crop intensification and farm income under climatic risk in West Africa. [P-3330-32]

In West African countries, agricultural production per capita has decreased over the past half century. With continued population growth and the diminishing availability of marginal arable land, pressure on land is rapidly increasing and there is now a common view that crop yield must be increased in this region, especially as there is a wide gap between actual and potential yields. Although there are several factors which may explain this yield gap, the fact that agricultural production takes place in resource-constrained farm households exposed to risk is widely recognized as being important. Indeed, risk discourages the adoption of high-risk, high-return agricultural technologies, which in turn impedes the improvement of yields. In order to assess how climatic risk constrains intensification strategy in West Africa, we built and calibrated a bioeconomic farm simulation model predicting the choice to intensify crops or livestock as depending on the availability of key policies in the economic environment of farms, for typical cases in the groundnut basin of Senegal. These cases include two regions contrasted in terms of rainfall (Sine and Saloum) and in each region two typical farms, representing poor and less poor farmers. The model features uncertainty in weather (hence yields) and crop prices, farmer's risk aversion, nine cropping systems representing millet, maize and groundnut with various intensification levels, and the main interactions between crop and livestock: draught animal power, the feeding of animals with suitable crop products (groundnut haulms, cereal straw) and the production of farm manure. Farmers are constraint by land, labour, cash and credit availability. 180 households were surveyed to build the socio-demographic and economic dataset used by the model, and agronomic data were collected from 206 fields. These key policies analysed are (i) weather index insurances against drought impact on crop yields, either subsidised or not, (ii) subsidies to short term credit for purchasing farm inputs, (iii) subsidies to fertilizer, and (iv) direct payments to farmers. In our simulations, under the current climate and prices of agricultural products and inputs, all these policies appear favourable to the increase of farmers' expected utility for typical farms representing the vast majority of farms in the groundnut basin. Apart for insurance, all of them appear also favourable to intensification of coupled crop and livestock activities for those typical farms. Insurance appears favourable to this intensification strategy only for farms located in the northern part of the region studied, where climatic risk is higher. Among the scenario tested, for most typical farms, combining unsubsidized insurance with subsidized credit appeared as the best use of a given amount of public funds in support of crop intensification: subsidized credit allows the farmers to buy costly inputs while insurance reduces the risk that a drought prevents them from reimbursing the credit. Direct payments also rank high in this respect, because they efficiently mitigate the cash constraint. The amount of subsidies required to obtain a given increase of the value of farm production varies across farm types and subzones in the region, but is relatively reasonable. These results suggest that crop intensification is currently relatively close to becoming a relevant option for farmers and that public policies may favour it by improving the economic environment of farms. (Texte intégral

Study of the competitiveness of allochtonous sterile males during the tsetse eradication campaign in Senegal

Since 2007, the Government of Senegal launched an eradication campaign against the only species present in the Niayes area (Glossina palpalis gambiensis Vanderplank). The fly occupies an isolated pocket of 525km2 but keeps transmitting animal trypanosomoses to livestock with a high incidence, thus hampering the intensification of cattle production systems. An area-wide integrated pest management strategy was selected that targets the entire infested area and combines control methods efficient at high density of the target population (insecticide-treated targets and cattle) with the sterile insect technique (SIT) that shows inverse density dependent properties. The sterile male insects will be released as chilled adults from gyrocopters by air, using a newly developed automatic release machine. One of the principal prerequisites for successful SIT, apart from the availability of sterile males in adequate numbers, is to make sure that the laboratory strain is competitive with the wild males in the target area. This is all the more important as in Senegal, the local target populations are genetically isolated from the G. p. gambiensis populations of the main tsetse belt, and they have a more xerophylous behaviour (the annual rainfall in the Niayes area is below 500mm). The mating compatibility of the strain maintained at the CIRDES, Burkina Faso for more than 40 years (named BKF) with that of the target area in the Niayes was confirmed at the FAO/IAEA Insect Pest Control Laboratory in Seibersdorf, Austria. Thereafter, we released more than 140,000 sterile male flies (BKF) in 4 sites to study their dispersal, survival and competitiveness (recapture rate of 5%). The latter parameter was measured using Fried's index (F), thanks to availability of data on natural abortion rates for more than 3 years in all the release sites before these mark-release-recapture experiments. The BKF strain performed well in 3 out of the 4 sites (daily mortality rates of 15-16%, daily displacement of 420-705m and F of 0.37±0.29), but underperformed in the park of Hann inside Dakar city where pollution is high (mortality rates of 24%, p<0.05). An introgressed strain, constructed using a crossing schedule with BKF female flies and local SEN male flies (5 generations) will be tested soon in this site. Interestingly, the males from the BKF strain performed better in Senegal than in Burkina Faso recently, suggesting some degree of satyrism in this species. (Texte integral

La filière arachide de bouche : technologie post-récolte et valorisation des produits

L'obtention de graines décortiquées d'arachide de bouche suit le même processus que les semences prêtes à l'emploi, jusqu'avant le traitement fongicide. Le croissance du marché international ne pouvant être totalement couverte par les grands pays producteurs, l'Afrique bénéficie d'une nouvelle opportunité de prise de parts de marché. L'article décrit les normes générales de production et de collecte qui doivent être respectées par le producteur et par l'organisme ou le service responsable de la commercialisation. La production de gousses triées pour l'exportation est étudié