Restoring Soil Fertility in Sub-Saharan Africa: Technical and Economic Issues

Land Economics/Use, Downloads July 2008-June 2009: 9,

Cotton in West and Central Africa: Adapting a Successful Model to New Realities

Produced for review by the United States Agency for International Development under the WACIP project funded by USAID (Programme de Renforcement du Secteur Coton en Afrique de l'Ouest et du Centrecotton, Africa, Crop Production/Industries, Q13,

Ability, Parental Valuation of Education and the High School Dropout Decision

We use a large, rich Canadian micro-level dataset to examine the channels through which family socio-economic status and unobservable characteristics affect children's decisions to drop out of high school. First, we document the strength of observable socio-economic factors: our data suggest that teenage boys with two parents who are themselves high school dropouts have a 16% chance of dropping out, compared to a dropout rate of less than 1% for boys whose parents both have a university degree. We examine the channels through which this socio-economic gradient arises using an extended version of the factor model set out in Carneiro, Hansen, and Heckman (2003). Specifically, we consider the impact of cognitive and non-cognitive ability and the value that parents place on education. Our results support three main conclusions. First, cognitive ability at age 15 has a substantial impact on dropping out. Second, parental valuation of education has an impact of approximately the same size as cognitive ability effects for medium and low ability teenagers. A low ability teenager has a probability of dropping out of approximately .03 if his parents place a high value on education but .36 if their education valuation is low. Third, parental education has no direct effect on dropping out once we control for ability and parental valuation of education. Our results point to the importance of whatever determines ability at age 15 (including, potentially, early childhood interventions) and of parental valuation of education during the teenage years. We also make a small methodological contribution by extending the standard factor based estimator to allow a non-linear relationship between the factors and a covariate of interest. We show that allowing for non-linearities has a substantial impact on estimated effects.Idiosyncratic Shocks, Disability, Insurance, Marriage

Ability, parental valuation of education and the high school dropout decision

We use a large, rich Canadian micro-level dataset to examine the channels through which family socio-economic status and unobservable characteristics affect children's decisions to drop out of high school. First, we document the strength of observable socio-economic factors: our data suggest that teenage boys with two parents who are themselves high school dropouts have a 16 per cent chance of dropping out, compared to a dropout rate of less than 1 per cent for boys whose parents both have a university degree. We examine the channels through which this socio-economic gradient arises using an extended version of the factor model set out in Carneiro, Hansen, and Heckman (2003). Specifically, we consider the impact of cognitive and non-cognitive ability and the value that parents place on education. Our results support three main conclusions. First, cognitive ability at age 15 has a substantial impact on dropping out. The highest ability individuals are predicted never to drop out regardless of parental education or parental valuation of education. In contrast, the lowest ability teenagers have a probability of dropping out of approximately .36 if their parents have a low valuation of education. Second, parental valuation of education has a substantial impact on medium and low ability teenagers. A low ability teenager has a probability of dropping out of approximately .03 if his parents place a high value on education but .36 if their educational valuation is low. These effects are estimated while conditioning on ability at age 15. Thus, under some assumptions, they reflect parental influences during the upper teenage years and are in addition to any impact they might have in the early childhood years leading up to age 15. Third, parental education has no direct effect on dropping out once we control for ability and parental valuation of education. Overall, our results point to the importance of whatever determines ability at age 15 (including, potentially, early childhood interventions) and of parental valuation of education during the teenage years. Our work also provides a small methodological contribution by extending the standard factor based estimator to allow a more non-linear relationship between the factors and a co-variate of interest. We show that allowing for non-linearities has a substantial impact on estimated effects.

Involvement of Park and Recreation Professionals in Pedestrian Plans

Professionals from many different disciplines are finding innovative ways to work together to increase physical activity to help create healthier communities. One process that can provide a focal point for promoting physical activity by park and recreation professionals, land use and transportation planners, public health practitioners, and other stakeholders is the development and implementation of pedestrian plans. A pedestrian plan is a public document that lays out a community’s vision for future pedestrian activity, identifies the actions required to realize that vision, ties actions to funding sources, and describes implementation and use. The purpose of this study was to explore whether park and recreation professionals were involved in creating pedestrian plans and how park and recreation elements were represented in these plans. To answer this, we identified, collected, and conducted a content analysis of all pedestrian plans in North Carolina. Among the 41 regional, county, and municipal pedestrian plans, park and recreation professionals were mentioned in the plan 56% of the time. Seventy-one percent (n=29) had a vision statement; however, among those only five vision statements mentioned parks or recreation. In all five cases, when a plan contained a vision statement that mentioned parks or recreation, there was a park and recreation member involved in the development of the plan. A higher percent of plans with a park and recreation professional involved were more likely to list parks in their land use analysis (74% vs. 67%). Park master plans were mentioned in the pedestrian plans 29% of the time; however, a lower percent of plans with a park and recreational professional involved mentioned a park master plan (26% vs. 33%). Given the potential importance of pedestrian plans in creating connections for pedestrians, park and recreation professionals are encouraged to become involved in the pedestrian planning process if they are not already. Parks can offer opportunities for residents of diverse ages and cultures to come together to socialize and engage in health-promoting activities. Integrating a park and recreation perspective into a more comprehensive planning process can enhance access to parks, inform programs, support multiple community goals, facilitate efficient use of resources, and promote partnerships for greater sustainabilit

Controlling the risk of cross-contamination from the building drainage system using the reflected wave technique to identify depleted water trap seals

The appliance trap seal remains the primary defence against cross-contamination from the foul air present within the building drainage system. As an identified vector in the spread of severe acute respiratory syndrome (SARS) in Hong Kong in 2003, trap seal failure has been confirmed as a significant, and potentially fatal, risk to public health. Prevention of trap seal failure depends upon both good design, to limit the air pressure transients propagated within the system, and good maintenance. However, current maintenance regimes rely solely on visual inspections which is time consuming and often impractical to implement in large complex buildings. This thesis documents the development of a novel approach to system maintenance whereby the threat of cross-contamination of disease is minimised by the remote monitoring of trap seal status. This was approached through the application and development of the reflected wave technique which is fundamentally based upon the characteristic reflection coefficients of system boundary conditions. An extensive programme of laboratory experiments and field trials were carried out to collect transient pressure data which, together with results from an existing mathematical model (AIRNET), developed by the Drainage Research Group at Heriot- Watt University, have been used to validate the proposed technique and to formulate a practical methodology which may be applied to any building drainage system. Automatic system diagnosis, which would in the future allow the proposed technique to be integrated as an automated system test, was provided by the development of the trap condition evaluator (TRACER) program by this author. Incorporating a time series change detection algorithm, the TRACER program accurately detects and locates a depleted trap seal by automatically identifying the return time of the trap’s reflection. The reflected wave technique has been demonstrated as a successful approach to depleted trap identification provided that the wave propagation speed is known and the dampening influence of the junction effect (which can delay the observed reflection return time) are taken into account. The reflected wave technique offers a remote and non-invasive approach to maintaining the building drainage system and provides, for the first time, a diagnostic tool to help prevent cross-contamination.Engineering and Physical Sciences Research Council (EPSRC

Quantitative analysis of ruminal methanogenic microbial populations in beef cattle divergent in phenotypic residual feed intake (RFI) offered contrasting diets

peer-reviewedBackground Methane (CH4) emissions in cattle are an undesirable end product of rumen methanogenic fermentative activity as they are associated not only with negative environmental impacts but also with reduced host feed efficiency. The aim of this study was to quantify total and specific rumen microbial methanogenic populations in beef cattle divergently selected for residual feed intake (RFI) while offered (i) a low energy high forage (HF) diet followed by (ii) a high energy low forage (LF) diet. Ruminal fluid was collected from 14 high (H) and 14 low (L) RFI animals across both dietary periods. Quantitative real time PCR (qRT-PCR) analysis was conducted to quantify the abundance of total and specific rumen methanogenic microbes. Spearman correlation analysis was used to investigate the association between the relative abundance of methanogens and animal performance, rumen fermentation variables and diet digestibility. Results Abundance of methanogens, did not differ between RFI phenotypes. However, relative abundance of total and specific methanogen species was affected (P < 0.05) by diet type, with greater abundance observed while animals were offered the LF compared to the HF diet. Conclusions These findings suggest that differences in abundance of specific rumen methanogen species may not contribute to variation in CH4 emissions between efficient and inefficient animals, however dietary manipulation can influence the abundance of total and specific methanogen species.Funding for the development and main work of this research was provided under the National Development Plan, through the Research Stimulus Fund, administered by the Department of Agriculture, Fisheries & Food, Ireland RSF 05 224