Discrete-time optimal preview control

There are many situations in which one can preview future reference signals, or future disturbances. Optimal Preview Control is concerned with designing controllers which use this preview to improve closed-loop performance. In this thesis a general preview control problem is presented which includes previewable disturbances, dynamic weighting functions, output feedback and nonpreviewable disturbances. It is then shown how a variety of problems may be cast as special cases of this general problem; of particular interest is the robust preview tracking problem and the problem of disturbance rejection with uncertainty in the previewed signal. . (', The general preview problem is solved in both the Fh and Beo settings. The H2 solution is a relatively straightforward extension ofpreviously known results, however, our contribution is to provide a single framework that may be used as a reference work when tackling a variety of preview problems. We also provide some new analysis concerning the maximum possible reduction in closed-loop H2 norm which accrues from the addition of preview action. / Name of candidate: Title of thesis: I DESCRIPTION OF THESIS Andrew Hazell Discrete-Time Optimal Preview Control The solution to the Hoo problem involves a completely new approach to Hoo preview control, in which the structure of the associated Riccati equation is exploited in order to find an efficient algorithm for computing the optimal controller. The problem tackled here is also more generic than those previously appearing in the literature. The above theory finds obvious applications in the design of controllers for autonomous vehicles, however, a particular class of nonlinearities found in typical vehicle models presents additional problems. The final chapters are concerned with a generic framework for implementing vehicle preview controllers, and also a'case study on preview control of a bicycle.Imperial Users onl

The Levy Institute Measure of Economic Well-Being: Estimates for Canada, 1999 and 2005

This report presents estimates of the Levy Institute Measure of Economic Well-Being (LIMEW) for a representative sample of Canadian households in 1999 and 2005. The results indicate that there was only modest growth in the average Canadian household’s total command over economic resources in the six years between 1999 and 2005. Although inequality in economic well-being increased slightly over the 1999-2005 period, the LIMEW was more equally distributed across Canadian households than more common income measures (such as after-tax income) in both 1999 and 2005. The median household’s economic well-being was lower in Canada than in the United States in both years.LIMEW, well-being, income, earnings, wealth, public consumption, government expenditure, household production, inequality

"The Levy Institute Measure of Economic Well-Being: Estimates for Canada, 1999 and 2005"

This report presents estimates of the Levy Institute Measure of Economic Well-Being (LIMEW) for a representative sample of Canadian households in 1999 and 2005. The results indicate that there was only modest growth in the average Canadian household’s total command over economic resources in the six years between 1999 and 2005. Although inequality in economic well-being increased slightly over the 1999–2005 period, the LIMEW was more equally distributed across Canadian households than more common income measures (such as after-tax income) in both 1999 and 2005. The median household’s economic well-being was lower in Canada than in the United States in both years.Well-being, Inequality, Income, Wealth, Government Expenditure, Household Production, LIMEW, (Canada)

The future of small farms for poverty reduction and growth:

"The people operating small farms in developing countries have to cope with the risks of these small businesses and have long faced heavy challenges. Today, these challenges are particularly severe, and the aspirations of young people on small farms have changed. Globalization and the integration of international markets are stimulating intense competition, offering some opportunities but also new risks. In light of these pressures and others, many of the world's millions of small farmers are simply not making it. Indeed, half of the world's undernourished people, three-quarters of Africa's malnourished children, and the majority of people living in absolute poverty live on small farms. The transformation of the small-farm economy is one of the biggest economic challenges of our time. For some, it entails growth into specialized, market-oriented farms; for others, part-time farming combined with off-farm rural jobs; and for others, a move out of agriculture. The pathways of transformation differ by region and location and will take decades. Policy must take a long-run view to support and guide this process efficiently, effectively, and in social fairness. The role of women farmers and their livelihoods requires particular attention. In this paper, Peter Hazell, Colin Poulton, Steve Wiggins, and Andrew Dorward address several crucial questions. Do small farms in fact have a future? In what situations can small farms succeed? What strategies are most appropriate for helping to raise small-farm productivity? The authors review both sides of the debate over the future of small farms before coming to their conclusions. Coming down firmly on the side of policy support for small farms, they point to small farms' significant potential for reducing poverty and inequity. They also clarify the differing roles of and needs for small farms in different country contexts and spell out a policy agenda for promoting small-farm development. This discussion paper is based on a literature review and the deliberations of an international workshop, “The Future of Small Farms,” organized by the International Food Policy Research Institute (IFPRI) 2020 Vision Initiative, the Overseas Development Institute (ODI), and Imperial College London in Wye, England, from June 26 to 29, 2005. (A proceedings volume for this workshop is available from IFPRI, www.ifpri.org/events/seminars/2005/smallfarms/sfproc.asp.) We hope that this discussion paper will help stimulate renewed attention among many stakeholders— including policymakers, researchers, the private sector, and nongovernmental organizations—to small-scale agricultural development. Healthy and productive small farms could serve as a crucial mechanism for achieving the poverty and hunger Millennium Development Goals. " From Foreword by Joachim von BraunPro-poor growth, Agriculture, Economic development, small farms, Poverty reduction, Sustainable livelihoods, Non-farm development, Rural-urban linkages, small farms,

"A Comparison of Inequality and Living Standards in Canada and the United States Using an Expanded Measure of Economic Well-Being"

We use the Levy Institute Measure of Economic Well-being (LIMEW), the most comprehensive income measure available to date, to compare economic well-being in Canada and the United States in the first decade of the 21st century. This study represents the first international comparison based on LIMEW, which differs from the standard measure of gross money income (MI) in that it includes noncash government transfers, public consumption, income from wealth, and household production, and nets out all personal taxes. We find that, relative to the United States, median equivalent LIMEW was 11 percent lower in Canada in 2000. By 2005, this gap had narrowed to 7 percent, while the difference in median equivalent MI was only 3 percent. Inequality was notably lower in Canada, with a Gini coefficient of 0.285 for equivalent LIMEW in 2005, compared to a US coefficient of 0.376-a gap that primarily reflects the greater importance of income from wealth in the States. However, the difference in Gini coefficients declined between 2000 and 2005. We also find that the elderly were better off relative to the nonelderly in the United States, but that high school graduates did better relative to college graduates in Canada.Well-Being; Living Standards; Inequality; Income; International Comparisons

Evasion of the toxic effects of oxygen

Oxygen is an efficient terminal electron acceptor in respiratory pathways. During aerobic respiration the electron transport chain generates free radical oxygen species as a result of electron leakage; this generation of toxic species is proportional to the oxygen tension (51). In addition, toxic oxygen species (TOS) may be formed exogenously, for example, by chemical processes or through radiation. TOS also result from the oxidative burst of polymorphonuclear leukocytes (PMN). Infection with Helicobacter pylori induces an inflammatory response (gastritis), which leads to an increase in the level of TOS in the gastric mucosa and the gastric juice (4, 24–26, 59). This increase in the level of toxic metabolites is probably the result of the generation of the superoxide anion (O2·− ), a reactive TOS, formed as part of the oxidative burst of PMN and enzymic activities of gastric epithelial cells. There is evidence that H. pylori infection leads to increased production of O2·− via NADPH oxidase in gastric cells, stimulated by lipopolysaccharide as well as xanthine oxidase, another mechanism for the generation of oxygen-derived free radicals (8, 80). In response to increased superoxide anion production in gastric tissue, changes have been detected in the level of expression of human superoxide dismutase (SOD) (12). Human gastric SOD exists as a cytoplasmic copper-zinc-superoxide dismutase (Cu, Zn-SOD) found in gland cells of the gastric body and antral mucosa, and as a manganese-superoxide dismutase (Mn-SOD) within mitochondria (63). An increase in the amount and activity of Mn-SOD has been observed in response to H. pylori infection and gastritis, whereas the amount and activity of the Cu, Zn-SOD remained constant or decreased slightly (39). It has been suggested that the induction of Mn-SOD is in response to increased cytokine production within the inflamed gastric mucosa (39). This situation is reversed following successful treatment of the infection (38). The data suggest that within the gastric environment H. pylori may be exposed to increased levels of TOS. In such an environment it is important for bacterial survival that the impact of such TOS be neutralized

Agricultural labour productivity, food prices and sustainable development impacts and indicators

In the last few years high and unstable food and agricultural commodity prices and concerns about population growth, increasing per capita food demands and environmental constraints have pushed agriculture and food production up national and international political, policy and research agendas. Drawing on both theory and empirical evidence, this paper argues that fundamental impacts of links between agricultural productivity sustainability and real food price changes are often overlooked in current policy analysis. This is exacerbated by a lack of relevant and accessible indicators for monitoring agricultural productivity sustainability and real food prices. Two relatively simple and widely applicable sets of indicators are proposed for use in policy development and monitoring. Historical series of these indices are estimated for selected countries, regions and the world. Their strengths, weaknesses and potential value are then discussed in the context of the need for better sustainable agricultural development and food security indicators in any post 2015 successors to the current MDGs

Advancing leadership in surgery : a realist review of interventions and strategies to promote evidence-based leadership in healthcare

Background: Healthcare systems invest in leadership development of surgeons, surgical trainees, and teams. However, there is no agreement on how interventions should be designed, or what components they must contain to be successful. The objective of this realist review was to generate a programme theory explaining in which context and for whom surgical leadership interventions work and why. Methods: Five databases were systematically searched, and articles screened against inclusion considering their relevance. Context-mechanism-outcome configurations (CMOCs) and fragments of CMOCs were identified. Gaps in the CMOCs were filled through deliberation with the research team and stakeholder feedback. We identified patterns between CMOCs and causal relationships to create a programme theory. Results: Thirty-three studies were included and 19 CMOCs were developed. Findings suggests that interventions for surgeons and surgical teams improve leadership if timely feedback is delivered on multiple occasions and by trusted and respected people. Negative feedback is best provided privately. Feedback from senior-to-junior or peer-to-peer should be delivered directly, whereas feedback from junior-to-senior is preferred when delivered anonymously. Leadership interventions were shown to be most effective for those with awareness of the importance of leadership, those with confidence in their technical surgical skills, and those with identified leadership deficits. For interventions to improve leadership in surgery, they need to be delivered in an intimate learning environment, consider implementing a speak-up culture, provide a variety of interactive learning activities, show a genuine investment in the intervention, and be customised to the needs of surgeons. Leadership of surgical teams can be best developed by enabling surgical teams to train together. Conclusions: The programme theory provides evidence-based guidance for those who are designing, developing and implementing leadership interventions in surgery. Adopting the recommendations will help to ensure interventions are acceptable to the surgical community and successful in improving surgical leadership. Trial registration: The review protocol is registered with PROSPERO (CRD42021230709)

DPOAEs in Children With Sickle Cell Disease

The purpose of this study was to investigate distortion product otoacoustic emissions (DPOAEs) in young normal-hearing children with sickle cell disease (SCD). It was hypothesized that the prevalence of DPOAEs and response amplitudes would be lower than those in children with normal hemoglobin due to suspected compromised cochlear function as a result of vaso-occlusive events characteristic of SCD. Twenty African-American children with SCD and 15 African-American children with normal hemoglobin participated. Distortion product OAEs were evoked by thirteen primary tone pairs with f2 frequencies ranging from 1000 to 4500 Hz. The primary tones were presented at and L1 and L2 levels of 70 and 60 dB SPL (high) and 50 and 40 dB SPL (low), respectively. The findings of this study were completely unexpected and contrary to our original hypotheses. The likelihood of detecting a DPOAE response was not related to the clinical status of the children. Distortion product OAE amplitudes were significantly larger for children with SCD (p = .01). Educational Objectives: After completing this article the reader will (1) have a basic knowledge of the audiometric complications of sickle cell disease and (2) appreciate the differences in DPOAEs between young normal-hearing children with sickle cell DPOAEs in Children With Sickle Cell Disease 3 disease and young normal-hearing children with normal hemoglobin

Peat humification records from Restionaceae bogs in northern New Zealand as potential indicators of Holocene precipitation, seasonality, and ENSO

In comparison with temperature reconstructions, New Zealand proxy records for paleo-precipitation are rare, despite the importance of precipitation in contemporary climate variability and for projected climate impacts. In this study, records of mid-late Holocene palaeomoisture variation were derived for two hydrologically separate ombrotrophic Restionaceae bogs in northern New Zealand, based on peat humification analysis. At each site, three cores were analysed for peat humification, facilitating both intra- and inter-site comparisons. Age models for the six sequences were developed using radiocarbon dating and tephrochronology. Twelve tephras (including six cryptotephras) were recognised, four of which were used to precisely link the two sites and to define start and end points for the records at 7027 ± 170 (Tuhua tephra) and 1718 ± 10 cal yr BP (Taupo tephra) (2σ-age ranges), respectively. We find individual differences between the six peat humification records at short-term timescales that are presumably due to local site factors, in particular changing vegetation and microtopography, or to changes in the composition of the material analysed. Stronger longer-term coherence is observed between all six records but is attributed to slow anaerobic decay over time because the implied trend towards wetter summers in the late Holocene cannot be corroborated by independent climate proxies. Despite these confounding factors, centennial scale shifts in bog surface wetness are a pervasive feature of all six records with varying degrees of overlap in time that show strong correspondence with El Niño-Southern Oscillation reconstructions from the eastern equatorial Pacific. These results indicate the potential for peat humification records from New Zealand's ombrotrophic bogs to elucidate past climate variability and also demonstrate the importance of developing multiple well-dated profiles from more than one site