Does urban agriculture help prevent malnutrition?

Previous research has suggested that urban agriculture has a positive impact on the household food security and nutritional status of low-socioeconomic status groups in cities in Sub-Saharan Africa, but a formal test of the link between semisubsistence urban food production and nutritional status has not accompanied these claims. This paper seeks to redress this gap in the growing literature on urban agriculture through an analysis of the determinants of the nutritional status of children under five in Kampala, Uganda, where roughly one-third of all households in the sample engage in some form of urban agriculture. When controlling for other individual child, maternal, and household characteristics, these data indicate that urban agriculture has a positive, significant association with higher nutritional status of children, particularly height-for-age. Several pathways by which this relationship is manifested are suggested, and the implications of these results for urban food and nutrition policy and urban management are briefly discussed.Food policies. ,Urban agriculture. ,Food security Household. ,Children Nutrition. ,Nutritional status ,

Neutrino Bremsstrahlung Process in highly degenerate magnetized electron gas

In this article the neutrino bremsstrahlung process is considered in presence of strong magnetic field, though the calculations for this process in absence of magnetic field are also carried out simultaneously. The electrons involved in this process are supposed to be highly degenerate and relativistic. The scattering cross sections and energy loss rates for both cases, in presence and absence of magnetic field, are calculated in the extreme-relativistic limit. Two results are compared in the range of temperature $5.9\times 10^{9}$ K $< T\leq 10^{11}$ K and magnetic field $10^{14} - 10^{16}$ G at a fixed density $\sim 10^{15}$ $gm/cc$, a typical environment during the cooling of magnetized neutron star. The interpretation of our result is briefly discussed and the importance of this process during the stellar evolution is speculated.Comment: 12 pages including 2 figures and 1 tabl

Tunneling mechanism of light transmission through metallic films

A mechanism of light transmission through metallic films is proposed, assisted by tunnelling between resonating buried dielectric inclusions. This is illustrated by arrays of Si spheres embedded in Ag. Strong transmission peaks are observed near the Mie resonances of the spheres. The interaction among various planes of spheres and interference effects between these resonances and the surface plasmons of Ag lead to mixing and splitting of the resonances. Transmission is proved to be limited only by absorption. For small spheres, the effective dielectric constant can be tuned to values close to unity and a method is proposed to turn the resulting materials invisible.Comment: 4 papges, 5 figure

Far-from-constant mean curvature solutions of Einstein's constraint equations with positive Yamabe metrics

In this article we develop some new existence results for the Einstein constraint equations using the Lichnerowicz-York conformal rescaling method. The mean extrinsic curvature is taken to be an arbitrary smooth function without restrictions on the size of its spatial derivatives, so that it can be arbitrarily far from constant. The rescaled background metric belongs to the positive Yamabe class, and the freely specifiable part of the data given by the traceless-transverse part of the rescaled extrinsic curvature and the matter fields are taken to be sufficiently small, with the matter energy density not identically zero. Using topological fixed-point arguments and global barrier constructions, we then establish existence of solutions to the constraints. Two recent advances in the analysis of the Einstein constraint equations make this result possible: A new type of topological fixed-point argument without smallness conditions on spatial derivatives of the mean extrinsic curvature, and a new construction of global super-solutions for the Hamiltonian constraint that is similarly free of such conditions on the mean extrinsic curvature. For clarity, we present our results only for strong solutions on closed manifolds. However, our results also hold for weak solutions and for other cases such as compact manifolds with boundary; these generalizations will appear elsewhere. The existence results presented here for the Einstein constraints are apparently the first such results that do not require smallness conditions on spatial derivatives of the mean extrinsic curvature.Comment: 4 pages, no figures, accepted for publication in Physical Review Letters. (Abstract shortenned and other minor changes reflecting v4 version of arXiv:0712.0798

Programmable telemetry system Patent

Time division multiplexed telemetry transmitting system controlled by programmed memor

The use of implicit evidence for relevance feedback in web retrieval

In this paper we report on the application of two contrasting types of relevance feedback for web retrieval. We compare two systems; one using explicit relevance feedback (where searchers explicitly have to mark documents relevant) and one using implicit relevance feedback (where the system endeavours to estimate relevance by mining the searcher's interaction). The feedback is used to update the display according to the user's interaction. Our research focuses on the degree to which implicit evidence of document relevance can be substituted for explicit evidence. We examine the two variations in terms of both user opinion and search effectiveness

Does geographic targeting of nutrition interventions make sense in cities?

Although most developing country cities are characterized by pockets of substandard housing and inadequate service provision, it is not known to what degree low incomes and malnutrition are confined to specific neighborhoods. This analysis uses representative household surveys of Abidjan and Accra to quantify small-area clustering in service provision, demographic characteristics, consumption, and nutrition. Both cities showed significant clustering in housing conditions but not in nutrition, while income was clustered in Abidjan, but less so in Accra. This suggests that neighborhood targeting of poverty-alleviation or nutrition interventions in these and similar cities could lead to undercoverage of the truly needy.Food consumption. ,Human Nutrition. ,Urban poor Africa. ,Malnutrition Africa. ,Africa. ,

The constraints to good child care practices in Accra

Life in urban areas presents special challenges for maternal child care practices. Data from a representative survey of households with children less than 3 years of age in Accra were used to test a number of hypothesized constraints to child care, including various maternal (education, employment, marital status, age, health, ethnic group, migration status) and household-level factors (income, calorie availability, quality of housing and asset ownership, availability of services, household size, and crowding). An age-specific child care index was created using recall data on maternal child feeding practices and use of preventive health services. A hygiene index was created from spot check observations of proxies of hygiene behaviors. Multivariate analyses showed that maternal schooling was the most consistent constraint to both the care and the hygiene index. None of the household-level characteristics were associated with the care index, but better housing quality and access to garbage collection services were associated with better hygiene. Female head of household and larger family size were associated with poorer hygiene. The programmatic implications of these findings for nutrition education and behavior change interventions in Accra are discussed. The focus is on using the information to target the right practices to be modified as well as the main constraints to their adoption.FCND ,Child care. ,Ghana. ,Maternal and infant welfare Developing countries. ,Urban health. ,

Good care practices can mitigate the negative effects of poverty and low maternal schooling on children's nutritional status

This study uses data from a representative survey of households with preschoolers in Accra, Ghana to (1) examine the importance of care practices for children's height-for-age z-scores (HAZ); and (2) identify subgroups of children for whom good maternal care practices may be particularly important. Good caregiving practices related to child feeding and use of preventive health services were a strong determinant of children's HAZ, specially among children from the two lower income terciles and children whose mothers had less than secondary schooling. In this population, good care practices could compensate for the negative effects of poverty and low maternal schooling on children's HAZ. Thus, effective targeting of specific education messages to improve child feeding practices and use of preventive health care could have a major impact on reducing childhood malnutrition in Accra.Health services. ,Child care. ,Child Feeding. ,Poverty. ,

On the dependence of the avalanche angle on the granular layer thickness

A layer of sand of thickness h flows down a rough surface if the inclination is larger than some threshold value theta which decreases with h. A tentative microscopic model for the dependence of theta with h is proposed for rigid frictional grains, based on the following hypothesis: (i) a horizontal layer of sand has some coordination z larger than a critical value z_c where mechanical stability is lost (ii) as the tilt angle is increased, the configurations visited present a growing proportion $_s of sliding contacts. Instability with respect to flow occurs when z-z_s=z_c. This criterion leads to a prediction for theta(h) in good agreement with empirical observations.Comment: 6 pages, 2 figure