Food Shortages and Seasonality in WoDaaBe Communities in Niger

Summary Data on WoDaaBe nomadic pastoralists in central Niger demonstrate that seasonality, through a coincidence of stress factors in the dry and transition seasons, clearly does reinforce poverty in this group. Although important, dry season hardship is merely a symptom of more crucial political and economic factors affecting the WoDaaBe economy. RESUME Pénurie de Nourriture et Variations Saisonnières dans les Communautés WoDaaBe au Niger Une collection de données sur les éleveurs nomades WoDaaBe dans le centre du Niger nous montre que les variations saisonnières par la coïncidence de facteurs de tension durant la saison sèche et les saisons de transition, renforcent très clairement le niveau de pauvreté de ce groupe. Bien qu'importante, la privation causée par la saison sèche n'est qu'un symptôme d'éléments économiques et politiques plus importants qui affectent l'économie des WoDaaBe. RESUMEN Escasez de alimentos y estacionalidad en las comunidades WoDaaBe de Niger La información sobre los pastores nómades de Niger central, demuestra claramente que la estacionalidad, a través de una coincidencia de factores tensionales en las estaciones seca y transicional, refuerza la pobreza de este grupo. Aunque la dureza de la estación seca es importante, sólo constituye un síntoma de factores políticos y económicos más cruciales que afectan la economía de WoDaaBe

Functional Expansions

Path dependence is omnipresent in social science, engineering, and finance. It reflects the influence of the past on the future, often expressed through functionals. However, non-Markovian problems are often infinite-dimensional, thus challenging from a conceptual and computational perspective. In this work, we shed light on expansions of functionals. First, we treat static expansions made around paths of fixed length and propose a generalization of the Wiener series$-$the intrinsic value expansion (IVE). In the dynamic case, we revisit the functional Taylor expansion (FTE). The latter connects the functional It\^o calculus with the signature to quantify the effect in a functional when a "perturbation" path is concatenated with the source path. In particular, the FTE elegantly separates the functional from future trajectories. The notions of real analyticity and radius of convergence are also extended to the path space. We discuss other dynamic expansions arising from Hilbert projections and the Wiener chaos, and finally show financial applications of the FTE to the pricing and hedging of exotic contingent claims.Comment: 39 pages, 7 figure

Complete-market models of stochastic volatility

In the Black–Scholes option-pricing theory, asset prices are modelled as geometric Brownian motion with a fixed volatility parameter σ, and option prices are deter-mined as functions of the underlying asset price. Options are in principle redundant in that their exercise values can be replicated by trading in the underlying. However, it is an empirical fact that the prices of exchange-traded options do not correspond to a fixed value of σ as the theory requires. This paper proposes a modelling framework in which certain options are non-redundant: these options and the underlying are modelled as autonomous financial assets, linked only by the boundary condition at exercise. A geometric condition is given, under which a complete market is obtained in this way, giving a consistent theory under which traded options as well as the underlying asset are used as hedging instruments

Designing indoor tangible games based on fuzzy localisation

International audienceWe present in this paper the development of an easy-to-adapt architecture for radio based, indoor geolocation; and the new opportunities it brings for game design. The weak precision of such systems, usually regarded as a problem, is considered here as a source of innovation for the design of pervasive games

L'ambiguïté structurale du fosterage dans une société matri-virilocale (Sereer Ndut, Sénégal)

L'ambiguïté structurale du fosterage dans une société matri-virilocale (Sereer Ndut, Sénégal)Les prêts temporaires d'enfants, dans la société ndut matrilinéaire et virilocale, visent à compenser les déséquilibres démographiques entre les segments d'un lignage et entre les descendants cognatiques d'une habitation. L'ambigui'té de l'institution réside dans les rôles contradictoires du tuteur, à la fois père de substitution et représentant de l'autorité lignagère, dont le garçon pourrait devenir l'héritier.L'auteur démontre l'adéquation du modèle ndut de redistribution de la main-d'œuvre infantile avec la réalité démographique, ainsi que sa concordance avec les modèles de fission du groupe domestique et de segmentation du matrilignage.Terrains propices aux stratégies, l'adoption et le fosterage provoquent des réactions ambiguës et contestataires chez les intéressés, particulièrement dans ces sociétés africaines où les statuts - de l'esclave au chef de lignage en passant par l'enfant adopté - s'étalent sur un continuum de relations.The Structural Ambiguity of Fosterage in a Matri-Virilocal Society (Sereer Ndut, Senegal)The temporary lending out of children, in the matrilineal and virilocal Ndut society, helps to compensate for the demographic imbalances between the segments of a lignage and between the cognatic descendants of a household. The ambiguity of this institution resides in the guardian's contradictory roles; for this person, whose ward could become his heir, acts both as a substitute father and as a representative of his lineage.The author demonstrates how the Ndut model of child manpower redistribution complements demographic reality. As well, the fission model of the household group is shown to concord with the segmentary model of matrilineage.Adoption and fosterage, a social context favourable for elaborating strategies, provoke ambiguous and conflicting reactions in the persons concerned, particularly so in African societies where the positions in society - from slave to chief of the lineage and including, of course, the adopted child - encompass a continuum of relationships

Résidence, tenure foncière, alliance dans une société bilinéaire (Sérèr du Sine et du Baol, Sénégal)

M. Dupire, A. Lericollais, B. Delpech et J.-M. Gastellu — Residence, Land Tenure and Marriage in a Double-Descent Society: The Serer from the Sine and Baol Regions of Senegal. This society is characterized by virilocal residence, double-descent, and matrilineal inheritance of non-consumable goods. Residential compounds are inherited in both the agnatic and the uterine lines, the relative proportion of each type of succession varying in the four villages under study. A compound may be divided into 'wards', 'kitchens', and, further down, 'uterine huts', each of these units corresponding to a specifie economic function. Starting from K. Gough's five types of residential categories, we define seven different patterns, the form most frequently found being the patrilocal extended family, the elementary family and a composite type of avuncular family, in that order. There is a significant correlation between residence patterns and inheritance of traditional offices. 'Kitchens' differ from compounds insofar as they can be matrilocal and chiefly consist of elementary families. While married sons often live in the same 'kitchen' with their fathers, nephews seldom cohabit with their MB. The 'uterine hut' is the primary unit of economic accumulation. The bilineal pattern of inheritance is also found in the four-level System of land-rights, with a correlation between land-rights and residence. Residential patterns and pre-ferential marriages tend to counterbalance the dispersal of a matrilineage's women resulting from virilocality.Dupire Marguerite, Lericollais André, Delpech Bernard, Gastellu Jean-Marc. Résidence, tenure foncière, alliance dans une société bilinéaire (Serer du Sine et du Baol, Sénégal).. In: Cahiers d'études africaines, vol. 14, n°55, 1974. pp. 417-452

Circuits de transmission sans fil à faible puissance pour dispositifs implantables

Les systèmes de télémétrie existants -- Architectures et circuits des systèmes d'émission -- Système de transmission pour applications biomédicales -- Système de transmission proposé

Local Volatility Calibration by Optimal Transport

The calibration of volatility models from observable option prices is a fundamental problem in quantitative finance. The most common approach among industry practitioners is based on the celebrated Dupire's formula [6], which requires the knowledge of vanilla option prices for a continuum of strikes and maturities that can only be obtained via some form of price interpolation. In this paper, we propose a new local volatility calibration technique using the theory of optimal transport. We formulate a time continuous martingale optimal transport problem, which seeks a martingale diffusion process that matches the known densities of an asset price at two different dates, while minimizing a chosen cost function. Inspired by the seminal work of Benamou and Brenier [1], we formulate the problem as a convex optimization problem, derive its dual formulation, and solve it numerically via an augmented Lagrangian method and the alternative direction method of multipliers (ADMM) algorithm. The solution effectively reconstructs the dynamic of the asset price between the two dates by recovering the optimal local volatility function, without requiring any time interpolation of the option prices