Inequalities in purchase of mosquito nets and willingness to pay for insecticide-treated nets in Nigeria: Challenges for malaria control interventions

Objective: To explore the equity implications of insecticide-treated nets (ITN) distribution programmes that are based on user charges. Methods: A questionnaire was used to collect information on previous purchase of untreated nets and hypothetical willingness to pay (WTP) for ITNs from a random sample of householders. A second survey was conducted one month later to collect information on actual purchases of ITNs. An economic status index was used for characterizing inequity. Major findings: The lower economic status quintiles were less likely to have previously purchased untreated nets and also had a lower hypothetical and actual WTP for ITNs. Conclusion: ITN distribution programmes need to take account of the diversity in WTP for ITNs if they are to ensure equity in access to the nets. This could form part of the overall poverty reduction strategy.This study received financial support from the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical diseases

Mind Your Calling

Mind Your Calling, a speach given for the Friends United Meeting in 1972.https://digitalcommons.georgefox.edu/arthur_roberts/1004/thumbnail.jp

The Lagrangian spectral relaxation model for differential diffusion in homogeneous turbulence

The Lagrangian spectral relaxation ~LSR! model is extended to treat turbulent mixing of two passive scalars (fa and fb) with different molecular diffusivity coefficients ~i.e., differential-diffusion effects!. Because of the multiscale description employed in the LSR model, the scale dependence of differential-diffusion effects is described explicitly, including the generation of scalar decorrelation at small scales and its backscatter to large scales. The model is validated against DNS data for differential diffusion of Gaussian scalars in forced, isotropic turbulence at four values of the turbulence Reynolds number (Rl538, 90, 160, and 230! with and without uniform mean scalar gradients. The explicit Reynolds and Schmidt number dependencies of the model parameters allows for the determination of the Re ~integral-scale Reynolds number! and Sc ~Schmidt number! scaling of the scalar difference z5fa2fb . For example, its variance is shown to scale like ^z2& ;Re20.3. The rate of backscatter (bD) from the diffusive scales towards the large scales is found to be the key parameter in the model. In particular, it is shown that bD must be an increasing function of the Schmidt number for Sc\u3c1 in order to predict the correct scalar-to-mechanical time-scale ratios, and the correct long-time scalar decorrelation rate in the absence of uniform mean scalar gradients

A study of optimum cowl shapes and flow port locations for minimum drag with effective engine cooling, volume 2

The listings, user's instructions, sample inputs, and sample outputs of two computer programs which are especially useful in obtaining an approximate solution of the viscous flow over an arbitrary nonlifting three dimensional body are provided. The first program performs a potential flow solution by a well known panel method and readjusts this initial solution to account for the effects of the boundary layer displacement thickness, a nonuniform but unidirectional onset flow field, and the presence of air intakes and exhausts. The second program is effectually a geometry package which allows the user to change or refine the shape of a body to satisfy particular needs without a significant amount of human intervention. An effort to reduce the cruise drag of light aircraft through an analytical study of the contributions to the drag arising from the engine cowl shape and the foward fuselage area and also that resulting from the cooling air mass flowing through intake and exhaust sites on the nacelle is presented. The programs may be effectively used to determine the appropriate body modifications or flow port locations to reduce the cruise drag as well as to provide sufficient air flow for cooling the engine

Optimal Moment Sets for Multivariate Direct Quadrature Method of Moments

The direct quadrature method of moments (DQMOM) can be employed to close population balance equations (PBEs) governing a wide class of multivariate number density functions (NDFs). Such equations occur over a vast range of scientific applications, including aerosol science, kinetic theory, multiphase flows, turbulence modeling, and control theory, to name just a few. As the name implies, DQMOM uses quadrature weights and abscissas to approximate the moments of the NDF, and the number of quadrature nodes determines the accuracy of the closure. For nondegenerate univariate cases (i.e., a sufficiently smooth NDF), the N weights and N abscissas are uniquely determined by the first 2N non-negative integer moments of the NDF. Moreover, an efficient product-difference algorithm exists to compute the weights and abscissas from the moments. In contrast, for a d-dimensional NDF, a total of (1 + d)N multivariate moments are required to determine the weights and abscissas, and poor choices for the moment set can lead to nonunique abscissas and even negative weights. In this work, it is demonstrated that optimal moment sets exist for multivariate DQMOM when N ) nd quadrature nodes are employed to represent a d-dimensional NDF with n ) 1-3 and d ) 1-3. Moreover, this choice is independent of the source terms in the PBE governing the time evolution of the NDF. A multivariate Fokker-Planck equation is used to illustrate the numerical properties of the method for d ) 3 with n ) 2 and 3

Automated design of minimum drag light aircraft fuselages and nacelles

The constrained minimization algorithm of Vanderplaats is applied to the problem of designing minimum drag faired bodies such as fuselages and nacelles. Body drag is computed by a variation of the Hess-Smith code. This variation includes a boundary layer computation. The encased payload provides arbitrary geometric constraints, specified a priori by the designer, below which the fairing cannot shrink. The optimization may include engine cooling air flows entering and exhausting through specific port locations on the body