Predicting Smoking Behaviors Among Junior High School Students in Ghana

Despite the rising rate of smoking in sub-Sahara African countries, measures to control the tobacco epidemic have been limited to developed countries. The purpose of the present study was to recommend predictive models for determining predictors of smoking tendencies among junior high school students in Ghana. The 2009 Global Youth Tobacco Survey (GYTS) served as the data source. The GYTS is a school-based survey designed to enhance the ability of countries to monitor tobacco use among youth and to guide the implementation and evaluation of tobacco control and prevention programs. Logit model and forward selection were used to choose predictive variables for smoking tendencies and behaviors. Receiver Operating Characteristic (ROC) curve, Area under the curve (AUC) and C-Index were validation tools used to assess the predictive power of recommended models. Results showed promising potential for different predictive models: where students smoked, having friends who smoked, having people smoke in their presence, chewing tobacco products, and a student's sex significantly predicted their smoking tendencies

Choosing policy instruments for pollution control : a review

This paper presents the design of cost effective interventions to protect the environment from excessive pollution in developing countries. The concept of intervention is motivated by the typical explanation for environmental problems in economic theory--external effects. The aim of the paper is to review the relevant theoretical and empirical economic literature in order: (a) to distill the principal lessons and evaluate general rules of thumb; and (b) to identify gaps that need to be filled in order to make them more accessible and relevant to developing countries. The paper defines broadly the range of policy instruments that can be used to address pollution problems in developing countries. It includes instruments that have traditionally been in the realm of public finance, such as taxes, prices and subsidies. But it also covers regulations and other instruments designed to affect the amount of pollution or to mitigate its damage. To limit the scope of this paper, the authors treat pollution control policies, but not policies to address other environmental problems, such as soil erosion, deforestation, desertification or other natural resource problems. Many of the principles presented, however, broadly relate to the problem of correcting for external effects, and can be applied to these other problems as well. It also focuses on domestic problems and does not deal explicitly with trans-national or global pollution externalities.Economic Theory&Research,Water and Industry,Health Monitoring&Evaluation,Pollution Management&Control,Environmental Economics&Policies

Optimal Minimum Wage Policy in Competitive Labor Markets

This paper provides a theoretical analysis of optimal minimum wage policy in a perfectly competitive labor market. We show that a binding minimum wage while leading to unemployment is nevertheless desirable if the government values redistribution toward low wage workers and if unemployment induced by the minimum wage hits the lowest surplus workers first. This result remains true in the presence of optimal nonlinear taxes and transfers. In that context, a minimum wage effectively rations the low skilled labor that is subsidized by the optimal tax/transfer system, and improves upon the second-best tax/transfer optimum. When labor supply responses are along the extensive margin, a minimum wage and low skill work subsidies are complementary policies; therefore, the co-existence of a minimum wage with a positive tax rate for low skill work is always (second-best) Pareto inefficient. We derive formulas for the optimal minimum wage (with and without optimal taxes) as a function of labor supply and demand elasticities and the redistributive tastes of the government. We also present some illustrative numerical simulations.minimum wages, tax policy, labor supply, demand elasticity

Rainwater Harvesting Potential for Domestic Water Supply in Edo State

In the face of increasing scarcity of water resources, there is a need for communities to undertake audits of their current rainwater harvesting potential as a practical and promising alternative solution for water shortage. Despite the importance of rainwater harvest in socio-economic development of communities, very little information exists in the literature concerning it. This paper is an attempt to bridge this gap by examining the techniques and materials used for rainwater harvest with a focus on the geographical spread of its use and an analysis to support its wide acceptance by considering a case study from Edo State. Investigations also relate to health implications of rainwater harvest and impact on food production. Also, examined are institutional arrangements and policies guiding water supply and distribution in the state as opposed to rainwater harvest. The total volume of water supplied by the rain (in gallons), and the volume of conserved were evaluated from hydro-meteorological data collection system and through a survey in different senatorial districts of the state. The results of the analysis show that majority of the people empty their tanks mid-way into the dry season, suggesting that the current volume of the tanks is not enough to sustain the people with water during the dry season period. New constructions of bigger tanks are therefore recommended, particularly for families who use harvested rainwater for cassava processing.Rainwater, Harvesting, Edo State, Stream, Tanks

Scalar-Fluid theories: cosmological perturbations and large-scale structure

Recently a new Lagrangian framework was introduced to describe interactions between scalar fields and relativistic perfect fluids. This allows two consistent generalizations of coupled quintessence models: non-vanishing pressures and a new type of derivative interaction. Here the implications of these to the formation of cosmological large-scale structure are uncovered at the linear order. The full perturbation equations in the two cases are derived in a unified formalism and their Newtonian, quasi-static limit is studied analytically. Requiring the absence of an effective sound speed for the coupled dark matter fluid restricts the Lagrangian to be a linear function of the matter number density. This still leaves new potentially viable classes of both algebraically and derivatively interacting models wherein the coupling may impact the background expansion dynamics and imprint signatures into the large-scale structure.Comment: 1+30 pages, a figure

The Core Mass Growth and Stellar Lifetime of Thermally Pulsing Asymptotic Giant Branch Stars

We establish new constraints on the intermediate-mass range of the initial-final mass relation by studying white dwarfs in four young star clusters, and apply the results to study the evolution of stars on the thermally pulsing asymptotic giant branch (TP-AGB). We show that the stellar core mass on the AGB grows rapidly from 10% to 30% for stars with $M_{\rm initial}$ = 1.6 to 2.0 $M_\odot$. At larger masses, the core-mass growth decreases steadily to $\sim$10% at $M_{\rm initial}$ = 3.4 $M_\odot$. These observations are in excellent agreement with predictions from the latest TP-AGB evolutionary models in Marigo et al. (2013). We also compare to models with varying efficiencies of the third dredge-up and mass loss, and demonstrate that the process governing the growth of the core is largely the stellar wind, while the third dredge-up plays a secondary, but non-negligible role. Based on the new white dwarf measurements, we perform an exploratory calibration of the most popular mass-loss prescriptions in the literature. Finally, we estimate the lifetime and the integrated luminosity of stars on the TP-AGB to peak at $t$ $\sim$ 3 Myr and $E$ = 1.2 $\times$ 10$^{10}$ $L_\odot$ yr for $M_{\rm initial}$ $\sim$ 2 $M_\odot$ ($t$ $\sim$ 2 Myr for luminosities brighter than the RGB tip at $\log(L/L_{\odot})$ $>$ 3.4), decreasing to $t$ = 0.4 Myr and $E$ = 6.1 $\times$ 10$^{9}$ $L_\odot$ yr for stars with $M_{\rm initial}$ $\sim$ 3.5 $M_\odot$. The implications of these results are discussed with respect to general population synthesis studies that require correct modeling of the TP-AGB phase of stellar evolution.Comment: 14 pages, 7 figures, 4 tables. Accepted for publication in Ap

Detection of spin injection into a double quantum dot: Violation of magnetic-field-inversion symmetry of nuclear polarization instabilities

In mesoscopic systems with spin-orbit coupling, spin-injection into quantum dots at zero magnetic field is expected under a wide range of conditions. However, up to now, a viable approach for experimentally identifying such injection has been lacking. We show that electron spin injection into a spin-blockaded double quantum dot is dramatically manifested in the breaking of magnetic- field-inversion symmetry of nuclear polarization instabilities. Over a wide range of parameters, the asymmetry between positive and negative instability fields is extremely sensitive to the injected electron spin polarization and allows for the detection of even very weak spin injection. This phenomenon may be used to investigate the mechanisms of spin transport, and may hold implications for spin-based information processing