The development of rural manufacturing industry in Central Africa: with special reference to metalworking

In this thesis I argue that rural industry is a critical element in the development of poor African countries, and that its virtue has been recognised by a growing number of interventions in recent years. Particular benefits of rural industrialisation are the support of agriculture, improved availability of consumer items and repair services within the rural community, the generation of rural income and a contribution to the development of the national technology base. However, in spite of the attention this sector has received, there has so far been little evidence of rural industry thriving. The general failure of rural industry to develop indicates that either it is inherently unviable in a modern context or that the interventions concerned with it have been recurrently faulty. I contend that, while the degree to which rural industry may thrive depends upon the level of formal industrial activity in the country, it is essentially viable but that where interventions have taken place they have usually been inappropriate. The bulk of this thesis therefore examines what interventions would be appropriate to encourage this sector. I show that two conditions are essential. Firstly that interventions must take as their point of departure the existing context and practice of rural artisans, for example, training should take place within their normal working environment, depending only upon the resources to which they normally have access or to which they gain access by means of the training. Secondly that the target group for any intervention must have a significant degree of control over it. Innovation is argued to be a key determinant of sustainability. The significance of confidence and its contribution to innovation are established, identifying the crucial nature of innovation itself within the artisanal context. Rural manufacturing industry is unlikely to thrive unless conditioning and circumstances encourage artisanal practitioners to innovate. I examine the factors that encourage or inhibit innovation, particularly attitudes towards existing practices and the perceptions of external agents. As well as examining in depth specific factors such as innovation and the control of interventions, the thesis reviews all the resources required by rural industry in order to thrive and demonstrates the importance of a balance between them. However it is argued that skill development is the field in which external agencies can most usefully assist informal sector, rural industry and that the results of interventions must be capable of autonomous propagation if they are to have any significance

Hydrodynamic Fuel Containment in an Open‐Cycle Gas Core Nuclear Rocket

A thermal‐hydraulic model of an open‐cycle gas core nuclear rocket is used to examine the fuel containment characteristics of the system. A parametric analysis is performed which studies how the average containment time, average number density, and mass loading of the fuel vary as a function of several design and operational parameters. The containing effect of the injected fluids is studied by varying the velocity and injection angle of the outer wall flow. The effect of rocket acceleration on the containment of the fuel is also examined. The results offer both a qualitative and quantitative look at fuel containment, thereby providing another step toward establishing the feasibility, or lack thereof, of the open‐cycle gas core nuclear rocket.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87619/2/1415_1.pd

A neutronic study of the open-cycle gas core nuclear

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77172/1/AIAA-1994-2896-348.pd

Heat transfer model for an open‐cycle gas core nuclear rocket

A heat transfer model is developed to assess the propulsion capability of the open‐cycle gas core nuclear rocket. The model is used to determine the maximum specific impulse achievable without violating the wall material temperature and heat flux limits. For a 3000 MW reactor with a wall heat flux limit of 100 MW/m2, it is shown that a specific impulse of 3160 s and a thrust of 125 kN can be obtained.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87494/2/1083_1.pd

A Comprehensive Thermal‐Hydraulic Model of an Open‐Cycle Gas Core Nuclear Rocket

A thermal‐hydraulic model of an open‐cycle gas core nuclear rocket is developed. The two‐dimensional Navier‐Stokes equations, the energy equation, and the species diffusion equation are solved for high temperature two‐species gas flow. A description of the model and the method of solution is presented, as well as the results for a cylindrical gas core reactor design. The results provide valuable insight into the fluid flow and species mixing within an open‐cycle gas core nuclear rocket.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87616/2/473_1.pd

System Concepts for Affordable Fission Surface Power

This paper presents an overview of an affordable Fission Surface Power (FSP) system that could be used for NASA applications on the Moon and Mars. The proposed FSP system uses a low temperature, uranium dioxide-fueled, liquid metal-cooled fission reactor coupled to free-piston Stirling converters. The concept was determined by a 12 month NASA/DOE study that examined design options and development strategies based on affordability and risk. The system is considered a low development risk based on the use of terrestrial-derived reactor technology, high efficiency power conversion, and conventional materials. The low-risk approach was selected over other options that could offer higher performance and/or lower mass

Health Disparities Among Racial and Ethnic Minority Firefighters

ABSTRACT Background: Racial/ethnic minorities are substantially underrepresented in the fire service and this situation is unique when compared to similarly mentally and physically demanding and hazardous occupations such as the military and law enforcement. There is little systematic research to provide greater clarity about this significant disparity. The purpose of this study is to examine physical and behavioral health issues of racial/ethnic minority firefighters when compared to their white, non-Hispanic counterparts and potentially identify areas for future research that might assist in improving their substantial underrepresentation. Materials and Methods: We report the results of a secondary analysis of data combining the baseline evaluations of two different firefighter health studies, the Firefighter Injury and Risk Evaluation (FIRE) and Fuel 2 Fight (F2F) studies. Male career firefighters (N=1,404) were from 31 fire departments across the US and its territories. White, non-Hispanic firefighters comprised 72.5% of the sample (n=1,018) and 27.5% classified themselves as a racial/ethnic minority. Firefighters who agreed to participate comprised 94% (F2F) and 97% (FIRE) of those available and all underwent assessments including body composition, fitness, and general/behavioral health, and job satisfaction. Results: We examined differences in health and job status between minority and non-minority firefighters and between firefighters in minority- (MDCs) and white-dominated communities (WDCs). After adjusting for potential confounds, there were significant main effects for the individual minority status vs. non-minority status on both BMI and BF%, indicating that minority firefighters had significantly higher average BMI (28.8±0.3kg/m2) and BF% (24.7± 0.7%) when compared to their white, non-Hispanic colleagues (27.7±0.2kg/m2and 23.1±0.6% for BMI and BF%, respectively). Minority firefighters also were 59% more likely to be obese (adjusted [A]OR=1.59; 95% CI=1.16-2.18). Firefighters serving in MDCs reported significantly more poor health days (Mean±SE; 3.2±0.2 days) than firefighters serving in WDCs (2.8±0.2 days; p=0.038). In addition, minority firefighters reported significantly more poor health days (3.6±0.4 days) than their non-minority colleagues (2.8±0.2 days; p=0.003), while the interaction indicates that minority firefighters in MDCs reported more poor health days than the other groups (p Conclusions: Individual and community minority status (i.e., ethnic density effect) were both significantly associated with a number of important health status indicators, with racial/ethnic minority firefighters demonstrating greater risk for unfavorable body composition and more poor physical health days. In addition, minority firefighters in WDCs reported the highest prevalence of lifetime diagnosis of depression by a physician, while minority firefighters in MDCs had the lowest. Many of these health status indicators have recently been studied within the context of experiences with discrimination, demonstrating that racial discrimination is associated with greater risk for obesity, depression, and poor physical and mental health and could be contributing to health disparities and potentially negatively impacting racial/ethnic minority firefighter health, safety, and retention

Thrust enhancement of the gasdynamic mirror (GDM) fusion propulsion system

The gasdynamic mirror propulsion system is a device that utilizes a magnetic mirror configuration to confine a hot plasma to allow fusion reactions to take place while ejecting a fraction of the energetic charged particles through one end to generate thrust. Because the fusion fuel is generally an isotope of hydrogen, e.g., deuterium or tritium, this propulsion device is capable of producing very large specific impulses (e.g., 200,000 seconds) but at modest thrusts. Since large thrusts are desirable, not only for reducing travel time but also for lifting sizable payloads, we have examined methods by which GDM’s thrust could be enhanced. The first consists of utilizing the radiation generated by the plasma, namely bremsstrahlung and synchrotron radiation, to heat a hydrogen propellant which upon exhausting through a nozzle produces the additional thrust. We asses the performance in this case by using an ideal model that ignores heat transfer considerations of the chamber wall, and one that takes into account heat flow and wall temperature limitations. We find in the case of a DT burning plasma that although thrust enhancement is significant, it was more than offset by the large drop in the specific impulse and a concomitant increase in travel time. The second method consisted of not altering the original GDM operation, but simply increasing the density of the injected plasma to achieve higher thrust. It is shown that the latter approach is more effective since it is compatible with improved performance in that it reduces trip time but at the expense of larger vehicle mass. For a D-He3D-He3 burning device the use of hydrogen to enhance thrust appears to be more desirable since the radiated power that goes into heating the hydrogen propellant is quite large. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87386/2/1481_1.pd

The clinical effectiveness and cost-effectiveness of ablative therapies in the management of liver metastases: systematic review and economic evaluation

Background: Many deaths from cancer are caused by metastatic burden. Prognosis and survival rates vary, but survival beyond 5 years of patients with untreated metastatic disease in the liver is rare. Treatment for liver metastases has largely been surgical resection, but this is feasible in only approximately 20–30% of people. Non-surgical alternatives to treat some liver metastases can include various forms of ablative therapies and other targeted treatments.Objectives: To evaluate the clinical effectiveness and cost-effectiveness of the different ablative and minimally invasive therapies for treating liver metastases.Data sources: Electronic databases including MEDLINE, EMBASE and The Cochrane Library were searched from 1990 to September 2011. Experts were consulted and bibliographies checked.Review methods: Systematic reviews of the literature were undertaken to appraise the clinical effectiveness and cost-effectiveness of ablative therapies and minimally invasive therapies used for people with liver metastases. Studies were any prospective study with sample size greater than 100 participants. A probabilistic model was developed for the economic evaluation of the technologies where data permitted.Results: The evidence assessing the clinical effectiveness and cost-effectiveness of ablative and other minimally invasive therapies was limited. Nine studies of ablative therapies were included in the review; each had methodological shortcomings and few had a comparator group. One randomised controlled trial (RCT) of microwave ablation versus surgical resection was identified and showed no improvement in outcomes compared with resection. In two prospective case series studies that investigated the use of laser ablation, mean survival ranged from 41 to 58 months. One cohort study compared radiofrequency ablation with surgical resection and five case series studies also investigated the use of radiofrequency ablation. Across these studies the median survival ranged from 44 to 52 months. Seven studies of minimally invasive therapies were included in the review. Two RCTs compared chemoembolisation with chemotherapy only. Overall survival was not compared between groups and methodological shortcomings mean that conclusions are difficult to make. Two case series studies of laser ablation following chemoembolisation were also included; however, these provide little evidence of the use of these technologies in combination. Three RCTs of radioembolisation were included. Significant improvements in tumour response and time to disease progression were demonstrated; however, benefits in terms of survival were equivocal. An exploratory survival model was developed using data from the review of clinical effectiveness. The model includes separate analyses of microwave ablation compared with surgery and radiofrequency ablation compared with surgery and one of radioembolisation in conjunction with hepatic artery chemotherapy compared with hepatic artery chemotherapy alone. Microwave ablation was associated with an incremental cost-effectiveness ratio (ICER) of £3664 per quality-adjusted life-year (QALY) gained, with microwave ablation being associated with reduced cost but also with poorer outcome than surgery. Radiofrequency ablation compared with surgical resection for solitary metastases < 3 cm was associated with an ICER of –£266,767 per QALY gained, indicating that radiofrequency ablation dominates surgical resection. Radiofrequency ablation compared with surgical resection for solitary metastases ? 3 cm resulted in poorer outcomes at lower costs and a resultant ICER of £2538 per QALY gained. Radioembolisation plus hepatic artery chemotherapy compared with hepatic artery chemotherapy was associated with an ICER of £37,303 per QALY gained.Conclusions: There is currently limited high-quality research evidence upon which to base any firm decisions regarding ablative therapies for liver metastases. Further trials should compare ablative therapies with surgery, in particular. A RCT would provide the most appropriate design for undertaking any further evaluation and should include a full economic evaluation, but the group to be randomised needs careful selection.Source of funding: Funding for this study was provided by the Health Technology Assessment programme of the National Institute for Health Research