Where does education pay off in Sub-Saharan Africa ? Evidence from two cities of teh Republic of Congo

Using first-hand data from the 2009 Employment and Informal Sector Survey (EESIC) in the two largest cities of the Republic of Congo, Brazzaville and Pointe-Noire, we analyse the impact of education on labour market outcomes, and identify the segments where education pays off the most. Multivariate analyses of the risk of unemployment and sectoral choice indicate that young people face serious difficulties in the labour market: for most of them, their only choice is to remain unemployed or to join the informal sector. To measure the specific impact of schooling on earnings, we address issues related to sample selection and endogeneity of education in the earnings function. The results shed light on heterogeneity in the returns to schooling across the two main cities and institutional sectors. An important finding is that the informal sector does not systematically lag behind the formal sectors in terms of returns to education. We emphasize convex returns to education, meaning that the last years in secondary and tertiary schooling yield the highest returns, while those of primary education are generally lower. This convexity is also apparent in the informal sector, where education (albeit on another scale) again appears as an important determinant of earnings

Particle transport in density gradient driven TE mode turbulence

The turbulent transport of main ion and trace impurities in a tokamak device in the presence of steep electron density gradients has been studied. The parameters are chosen for trapped electron (TE) mode turbulence, driven primarily by steep electron density gradients relevant to H-mode physics, but with a transition to temperature gradient driven turbulence as the density gradient flattens. Results obtained through non-linear (NL) and quasilinear (QL) gyrokinetic simulations using the GENE code are compared with results obtained from a fluid model. Main ion and impurity transport is studied by examining the balance of convective and diffusive transport, as quantified by the density gradient corresponding to zero particle flux (peaking factor). Scalings are obtained for the impurity peaking with the background electron density gradient and the impurity charge number. It is shown that the impurity peaking factor is weakly dependent on impurity charge and significantly smaller than the driving electron density gradient.Comment: 11 pages, 6 figures. Submitted to Nuclear Fusion SP

Costs and benefits from utility-funded commissioning of energy- efficiency measures in 16 buildings

This paper describes the costs and savings of commissioning of energy- efficiency measures in 16 buildings. A total of 46 EEMs were commissioned for all 16 buildings and 73 deficiencies were corrected. On average, commissioning was marginally cost effective on energy savings alone, although the results were mixed among all 16 buildings. When considered as a stand-alone measure, the median simple payback time of 6.5 years under the low energy prices in the Pacific Northwest. Under national average prices the median payback time is about three years. In estimating the present value of the energy savings from commissioning we considered low and high lifetimes for the persistence of savings from deficiency corrections. Under the low- lifetime case the average present value of the energy savings ($0. 21/ft{sup 2}) were about equal to the average commissioning costs ($0. 23/ft{sup 2}). Under the high-lifetime case the savings ($0.51/ft{sup 2}) were about twice the costs. Again, the savings would be about twice as large under national average prices. The results are subject to significant uncertainty because of the small sample size and lack of metered data in the evaluation. However, the findings suggest that investments in commissioning pay off. Building owners want buildings that work as intended, and are comfortable, healthy, and efficient. It is likely that the non-energy benefits, which are difficult to quantify, are larger than the energy-savings benefits

A comparison of block and semi-parametric bootstrap methods for variance estimation in spatial statistics

Efron (1979) introduced the bootstrap method for independent data but it cannot be easily applied to spatial data because of their dependency. For spatial data that are correlated in terms of their locations in the underlying space the moving block bootstrap method is usually used to estimate the precision measures of the estimators. The precision of the moving block bootstrap estimators is related to the block size which is difficult to select. In the moving block bootstrap method also the variance estimator is underestimated. In this paper, first the semi-parametric bootstrap is used to estimate the precision measures of estimators in spatial data analysis. In the semi-parametric bootstrap method, we use the estimation of the spatial correlation structure. Then, we compare the semi-parametric bootstrap with a moving block bootstrap for variance estimation of estimators in a simulation study. Finally, we use the semi-parametric bootstrap to analyze the coal-ash data

Zonal flow generation in collisionless trapped electron mode turbulence

In the present work the generation of zonal flows in collisionless trapped electron mode (TEM) turbulence is studied analytically. A reduced model for TEM turbulence is utilized based on an advanced fluid model for reactive drift waves. An analytical expression for the zonal flow growth rate is derived and compared with the linear TEM growth, and its scaling with plasma parameters is examined for typical tokamak parameter values.Comment: 20 pages, 4 figure