The Provident Societies in the rural economy of Yaoundé, 1945-1960

African Studies Center Working Paper No. 3

Household budgets and women's incomes

African Studies Center Working Paper No. 28While explaining proposed studies of aspects of "household economics" to prospective informants in two different African societies, I have been advised very quickly that "Among us, a man and his wife do not share the same purse, and that "Over here, we have a men's side and a women's side. This paper explores some of the problems of applying a "household" methodology to the study of African rural economies. It focuses on one type of household study, namely budget analysis, and suggests that the classic assumption of the household as an undifferentiated decision-making unit applies poorly to many African kinship systems. The first part of the paper is a brief discussion of household methodology and its application to Africa. The second part is devoted to an analysis of the relationship between men's and women's incomes in the rural economy of the Beti of Southern Cameroun

The raw, the cooked, and the half-baked: a note on the division of labor by sex

African Studies Center Working Paper No. 4

The economic position of Beti widows, past and present

African Studies Center Working Paper No. 2

Women's work in the economy of the Cocoa belt: a comparison

African Studies Center Working Paper No. 7This paper is an empirical study of the cultural context and historical development of the division of labor by sex in two farming systems of the West African cocoa belt: the Yoruba of Western Nigeria and the Beti of South-Central Cameroun. Both societies are patrilineal. Both peoples inhabited the forest zone before the period of colonial rule, so that their hoe-farming systems had already adjusted to the forest environment before the cocoa era. The two societies differ, however, in overall political structure. The Yoruba had a centralised form of city-state government, while the Beti were organised in small village communities under autonomous headmen. The major difference which forms the theme of this paper is the different division of labor by sex in the indigenous economy. In a rough categorization of African farming systems, according to which sex does most of the work, the Yoruba would be classified as a male farming system, the Beti as a female farming system. [TRUNCATED

Unsteady forces on an accelerating plate and application to hovering insect flight

The aerodynamic forces on a flat plate accelerating from rest at fixed incidence in two-dimensional power-law flow are studied analytically and numerically. An inviscid approximation is made in which separation at the two plate edges is modelled by growing spiral vortex sheets, whose evolution is determined by the Birkhoff–Rott equation. A solution based on a similarity expansion is developed, valid when the scale of the separated vortex is much smaller than the plate dimension. The leading order is given by the well-known similarity growth of a vortex sheet from a semi-infinite flat plate, while equations at the second order describe the asymmetric sweeping effect of that component of the free-stream parallel to the plate. Owing to subtle cancellation, the unsteady vortex force exerted on the plate during the starting motion is independent of the sweeping effect and is determined by the similarity solution, to the order calculated. This gives a mechanism for dynamic stall based on a combination of unsteady vortex lift and pure added mass; the incidence angle for maximum vortex lift is $\arccos \sqrt{3/8}\,{\approx}\,52.2^\circ$ independent of the acceleration profile. Circulation on the flat plate makes no direct contribution. Both lift and drag force predictions from the unsteady inviscid theory are compared with those obtained from numerical solutions of the two-dimensional unsteady Navier–Stokes equations for an ellipse of high aspect ratio, and with predictions of Wagner's classical theory. There is good agreement with numerical results at high incidence and moderate Reynolds number. The force per unit span predicted by the vortex theory is evaluated for parameters typical of insect wings and is found to be in reasonable agreement with numerical simulations. Estimates for the shed circulation and the size of the start-up vortices are also obtained. The significance of this flow as a mechanism for insect hovering flight is discussed

Polymer-stabilized sialylated nanoparticles : synthesis, optimization, and differential binding to influenza hemagglutinins

During influenza infection, hemagglutinins (HAs) on the viral surface bind to sialic acids on the host cell's surface. While all HAs bind sialic acids, human influenza targets terminal α2,6 sialic acids and avian influenza targets α2,3 sialic acids. For interspecies transmission (zoonosis), HA must mutate to adapt to these differences. Here, multivalent gold nanoparticles bearing either α2,6- or α2,3-sialyllactosamine have been developed to interrogate a panel of HAs from pathogenic human, low pathogenic avian, and other species' influenza. This method exploits the benefits of multivalent glycan presentation compared to monovalent presentation to increase affinity and investigate how multivalency affects selectivity. Using a library-orientated approach, parameters including polymer coating and core diameter were optimized for maximal binding and specificity were probed using galactosylated particles and a panel of biophysical techniques [ultraviolet-visible spectroscopy, dynamic light scattering, and biolayer interferometry]. The optimized particles were then functionalized with sialyllactosamine and their binding analyzed against a panel of HAs derived from pathogenic influenza strains including low pathogenic avian strains. This showed significant specificity crossover, which is not observed in monovalent formats, with binding of avian HAs to human sialic acids and in agreement with alternate assay formats. These results demonstrate that precise multivalent presentation is essential to dissect the interactions of HAs and may aid the discovery of tools for disease and zoonosis transmission