We investigate in detail two multiuser opportunistic scheduling problems in centralized wireless systems: the scheduling of "delay-sensitive" flows with packet delay requirements of a few tens to few hundreds of milliseconds over the air interface, and the scheduling of "best-effort" flows with the objective of minimizing mean file transfer delay. Schedulers for delay-sensitive flows are characterized by a fundamental tradeoff between "maximizing total service rate by being opportunistic" and "balancing unequal queues (or delays) across users". In choosing how to realize this tradeoff in schedulers, our key premise is that "robustness" should be a primary design objective alongside performance. Different performance objectives -- mean packet delay, the tail of worst user's queue distribution, or that of the overall queue distribution -- result in remarkably different scheduling policies. Different design objectives and resulting schedulers are also not equally robust, which is important due to the uncertainty and variability in both the wireless environment and the traffic. The proposed class of schedulers offers low packet delays, less sensitivity to the scheduler parameters and channel characteristics, and a more graceful degradation of service in terms of the fraction of users meeting their delay requirements under transient overloads, when compared with other well-known schedulers. Schedulers for best-effort flows are characterized by a fundamental tradeoff between "maximizing the total service rate" and "prioritizing flows with short residual sizes". We characterize two regimes based on the "degree" of opportunistic gain present in the system. In the first regime -- where the opportunistic capacity of the system increases sharply with the number of users -- the use of residual flow-size information in scheduling will 'not' result in a significant reduction in flow-level delays. Whereas, in the second regime -- where the opportunistic capacity increases slowly with the number of users -- using flow-size information alongside channel state information 'may' result in a significant reduction. We then propose a class of schedulers which offers good performance in either regime, in terms of mean file transfer delays as well as probability of blocking for systems that enforce flow admission control. This thesis provides a comprehensive theoretical study of these fundamental tradeoffs for opportunistic schedulers, as well as an exploration of some of the practical ramifications to engineering wireless systems. / text

Headwater stream systems are important components of the overall hydrologic system. Forestry best management practices (BMP) are effective at minimizing non point source pollution from forest harvesting activities. Streamside management zones (SMZ) are one BMP used to protect surface water quality by maintaining shade near streams, filtering runoff, and minimizing soil disturbance near streams. An evaluation of BMP effectiveness on the watershed scale was conducted at the University of Kentucky’s Robinson Forest. Six watersheds were harvested using a two-age deferment harvest with one of three SMZ configurations applied to each watershed. Two unharvested watersheds served as controls. Treatment 1 was based on the current Kentucky Forest Practice Guidelines for Water Quality Management and included a 16.8 m SMZ with 50% canopy retention for perennial streams, a 7.6 m SMZ with no canopy retention for intermittent streams, and no SMZ or canopy retention for ephemeral streams with unimproved crossings. Treatment 2 also included a 16.8 m perennial SMZ but increased canopy retention to 100%, as well as a 7.6 m intermittent SMZ with 25% canopy retention, and retention of channel bank trees and use of improved crossings for ephemeral streams. Treatment 3 required a 33.5 m perennial SMZ with 100% canopy retention, a 16.8 intermittent SMZ with 25% canopy retention, and a 7.6 m ephemeral SMZ with retention of channel bank trees and use of improved crossings. Total suspended solids (TSS) concentration and turbidity was measured in storm samples in perennial and ephemeral streams, and in non-storm samples in perennial and intermittent streams. Nitrate-N, ammonium-N, and dissolved oxygen concentrations were also measured in non-storm samples in perennial and intermittent streams. Temperature and water level were recorded every 15 minutes for the duration of the study. Results showed that treatment 3 was able to maintain TSS concentrations and turbidity levels similar to those measured in unharvested control watersheds. Increases in nitrate-N and mean daily temperature were measured for all treatments. Ammonium-N and dissolved oxygen concentrations were not different from unharvested control watersheds for any treatment. Storm hydrograph separation did not result in consistent changes post-harvest for any treatment.

Strategic planning in conservation of natural protected areas should include a human component, since human activity can threaten the health of the natural site. It is the competition for the resources that makes management of these areas a contentious issue. Effective education is key in resolving such issues and in ensuring that informed decisions are made concerning the uses of these valuable natural assets. This study tests this assumption in two phases.The first phase addresses the need to present a wider picture on the current state of environmental education practices in Mexico: Who is engaging in environmental education practices? How important is it for their organization? Who are they targeting and which methods and settings are they choosing and what environmental issues are they addressing? To achieve this, we administered a survey to 118 representatives from conservation and environmental education agencies and organizations in Mexico. Results show that conservation non-governmental organizations (NGOs) are taking the lead in the field of environmental education in Mexico. Education appears to be an important tool that is used widely by environmental and conservation organizations. At the same time, there seems to be a serious lack of funding.The second phase concentrates on conservation education, a specific aspect of environmental education that focuses on biodiversity issues. This is a growing field in Mexico, thanks especially to the system of Natural Protected Areas and the supporting network of conservation NGOs. This phase of the study presented a comparative analysis of perceived roles of education in the conservation of nature, between Mexico and the US and between practitioners and funders. In this phase we also compared the prescribed parameters defined by well known frameworks from academia with those perceived by education and conservation practitioners. We used a combination of online surveying and content analysis to evaluate this issue. Results illustrate that there are similarities between Mexico and the U.S., but with key differences in the target audiences, methods and settings. Funders do not consider education one of their high priorities, while practitioners do. This discrepancy may hamper the growth and maturation of conservation education in Mexico.

Farmyard runoff, i.e. the effluent generated by the rain falling over farmyards, tracks and roofs, is a significant and overlooked source of nutrients and pathogens which degrades aquatic ecosystems through eutrophication, siltation and wildlife poisoning, raises public health concerns, and incurs considerable costs for society. Among other Best Management Practices implemented to address agricultural water pollution and help achieve compliance with the Water Framework Directive, Constructed Farm Wetlands (CFWs), i.e. shallow surface flow wetlands comprising several vegetated cells in series, are being recommended for remediation of farmyard runoff, due to their capacity to remove or store pollutants. Investigation is therefore needed of their long-term water treatment efficiency and ecological value to optimize their design and cost-effectiveness and minimize their negative externalities. The main aims of this study were to: 1) evaluate the treatment performance of CFWs and the link between design, hydrology and efficiency; 2) assess their ecological value and the influence of water quality and design on wetland ecology; 3) identify their costs, benefits and the way they are perceived by farmers; and 4) inform guidelines for the design, construction and aftercare of sustainable CFWs. Research focused on two CFWs in south-east Scotland, one at a dairy farm and one at a mixed beef-arable farm, which receive runoff from yards and roofs, field drainage and septic tank overflow. From February 2006 to June 2008, rainfall, evaporation, water levels and flow at the CFWs were monitored, and their treatment efficiency was assessed from water samples collected manually regularly or with automatic samplers during storm events, and analysed using standard methods. In addition, their ecological value was assessed twice a year from vegetation and aquatic macroinvertebrate surveys. Finally, semi-structured interviews with eight farmers and a farm advisor and discussions with three CFW designers in Scotland and Ireland allowed collection of technical and economic data on farm practices, CFW construction and maintenance, and helped assess CFW cost-effectiveness and acceptance by farmers. Both CFWs reduced pollutant concentrations between inlet and outlet, with efficiencies at CFW1 and CFW2 respectively of 87% and < 0% for five-day biochemical oxygen demand, 86% and 83% for suspended solids, 68% and 26% for nitrate/nitrite, 42% and 34% for ammonium, and 12% and 31% for reactive phosphorus. Nevertheless, the concentration of all pollutants at the outlet of CFW1, and concentration of nitrate/nitrite at the outlet of CFW2 frequently exceeded river water quality standards. Water treatment efficiency varied seasonally, being significantly lower in winter, mainly due to lower temperatures, increased volume of inputs and reduced residence time. The ecological value of the two CFWs differed greatly. At CFW1 and CFW2 respectively, 14 and 22 wetland plant species and 24 and 46 aquatic macroinvertebrate species (belonging to 13 and 27 BMWP scoring families respectively) were recorded, illustrating the greater biodiversity conservation value of CFW2, which was one year older, larger, cleaner, comprised several ponds with a combination of open water and densely vegetated areas, and was subsequently more structurally diverse. The socio-economic study revealed that, despite significant costs associated with their construction (£20 000-£50 000 ha-1) and maintenance (£900-£1500 ha-1 yr-1), CFWs may still represent a more cost-effective alternative than conventional methods. However, their adoption, implementation and sustainable use by farmers were conditioned by land availability and suitability, existing farm infrastructure, detailed information on limitations and maintenance requirements, and adequate financial support for both construction and aftercare. To ensure a long-term, consistent and efficient water treatment, and to enhance biodiversity and landscape, well-maintained, large, vegetated, multi-cell CFWs with shallow overflows are recommended. Their size should be adapted to local precipitation patterns and catchment characteristics. Keywords: agriculture, best management practice (BMP), biodiversity, constructed farm wetland (CFW), costs, farmyard runoff, water pollution, water treatment.

Au cours de ces dernières années, la notion de la gouvernance d’entreprise fait l’objet d’un regain d’intérêt en raison de la faillite spectaculaire et des pertes importantes de quelques grandes entreprises (Enron, Worldcom…). Ainsi, le thème de la gouvernance des entreprises a pris, une préoccupation cruciale des chefs d’entreprise ainsi que par les investisseurs institutionnels. En effet, l’intérêt pour les bonnes pratiques de gouvernance d’entreprise a pris une importance de premier rang. Suite à cette attention accordée par les investisseurs aux pratiques de gouvernance, la notation de la gouvernance d’entreprise est devenue une pratique de plus en plus courante soit à travers des services de notation spécialisés ou avec l’intégration du système de gouvernance d’entreprise dans la notation financière. Notre objectif est d’identifier, à partir d’un échantillon de 132 entreprises françaises cotées sur la période 2002-2008, une structure de gouvernance appréhender par le fonctionnement du conseil d’administration, la structure de propriété et les caractéristiques du dirigeant. Plus précisément, notre travail consiste à calculer un score de gouvernance d’entreprise, comportant plusieurs variables, selon la méthode d’enveloppement des données (DEA). Les résultats obtenus montrent que les firmes françaises interrogées possèdent un indice d’efficience de gouvernance de 68 %. Ainsi, nous avons pu identifier des rapports entre le score de gouvernance et les autres caractéristiques des firmes. Ensuite, nous avons pu déterminer les pratiques qui permettent d’améliorer la qualité de la gouvernance, tout en se basant sur la performance de la firme. Enfin, nous avons pu établir, à partir d’un système d’équations simultanées, un lien de causalité entre la gouvernance et la performance de la firme. / Corporate governance has been the subject of a renewed interest for a few years because of the spectacular bankruptcy and of the significant losses of some large companies (Enron, WorldCom, Vivendi…). Thus, the theme of corporate governance has taken a key concern of business leaders and institutional investors. Indeed, interest in good corporate governance practices has gained importance in the forefront. Following the attention given by investors in corporate governance practices, the rating of corporate governance has become a practice increasingly common either through specialized rating services or system integration of corporate governance in credit ratings. Our goal is to identify, from a sample of 132 French listed companies over the period 2002-2008, a governance structure for understanding the functioning of the board of directors, ownership structure and characteristics of the leader. Specifically, our work is to calculate a score of corporate governance, with multiple variables, using the method of data envelopment analysis (DEA). The results show that French firms surveyed have a governance efficiency index of 68 %. Thus, we were able to identify links between the governance score and the characteristics of firms. Finally, we have established, from a system of simultaneous equations, a causal link between governance and firm performance.

Being exposed to serious games showed that some simulations widely vary in quality and learning outcome. In order to get to the bottom of best practices a detailed review of business management simulation literature was conducted. Additionally, an industry analysis was performed, by interviewing 17 simulation companies, testing a range of full and demo games, and conducting secondary research. The findings from both research efforts were then collated and cross-referenced against each other in order to determine three things: firstly, the practices and features used by simulation companies that have not yet been the subject of academic research; secondly, the most effective features, elements and inclusions within simulations that best assist in the achievement of learning outcomes and enhancement the user experience; and finally, 'best practices' in teaching a business management course in a university or company with the assistance of a simulation. Identified gaps in the current research were found to include the effectiveness of avatars, transparent pricing and the benefits of competing the simulation against other teams as opposed to the computer. In relation to the second and third objectives of the research, the findings were used to compile a business plan, with detailed recommendations for companies looking to develop a new simulation, and for instructors implementing and coordinating the use of a simulation in a business management context. (author's abstract)

Syftet med studien var att undersöka hur socialsekreterare förhåller sig till barnets bästa i arbetet med familjer där föräldrarna har en intellektuell funktionsnedsättning. För att kunna besvara studiens syfte har en kvalitativ metod använts. Intervjuer har genomförts med fem socialsekreterare från fem olika kommuner i Mellansverige, verksamma inom barn- och ungdomsenheten. En kvalitativ innehållsanalys genomfördes för analys av intervjumaterialet och två huvudkategorier; "Hur långt kan vi sträcka oss innan vi säger stopp?" samt Rädsla och osäkerhet med sex tillhörande subkategorier framkom. Den första kategorin visar på en osäkerhet hos socialsekreterarna kring vad som är barnets bästa i familjer där föräldrarna har en intellektuell funktionsnedsättning. Andra kategorin tyder på att det finns en rädsla inför socialtjänsten hos de föräldrar som har en intellektuell funktionsnedsättning vilket kan försvåra arbetet med familjerna. Resultatet visar likt anknytningsteorin att en förälder kan vara hämmande för sitt barns utveckling om det brister i förmågan att se och förstå barnets signaler. En intellektuell funktionsnedsättning i sig är dock enligt denna studie inte avgörande för om barnet kommer få en trygg anknytning. En ökad kunskap kring barn som växer upp i familjer där föräldrarna har en intellektuell funktionsnedsättning kan hjälpa socialtjänsten och socialsekreterare i frågor om vad som är barnets bästa och ge en vägledning i vad som kan tänkas vara barnets bästa uppväxtmiljö. / The purpose of this study was to investigate how social workers relates to the child's best in the work with families where the parents have an intellectual disability. To answer the purpose of the study a qualitative method have been used. Interviews were conducted with five social workers from five different municipalities in central Sweden, active in the child and adolescent unit. A qualitative content analysis was used for analysis of the interview material and two main categories were found; "How far can we stretch ourselves before we say stop?", Fear and uncertainty and six associated subcategories emerged. The first category shows an uncertainty among social workers about what is the child's best in families where the parents have an intellectual disability. The other category indicates that there is a fear of social services from parents who have an intellectual disability which may hamper the work with the families. The result shows, like attachment theory, that a parent can be a disincentive to their child's development if it lacks the ability to see and understand the child's signals. An intellectual disability in itself is not, according to this studie, decisive in determining whether the child will have a secure attachment. An increased knowledge about children growing up in families where the parents have an intellectual disability can help social services and the social secretary in the questions about the child's best and provide a guide to what might be the child's best growing environment.

Robust algorithms for the approximation of functions are studied and developed in this thesis. Novel results and algorithms on piecewise polynomial interpolation, rational interpolation and best polynomial and rational approximations are presented. Algorithms for the extension of Chebfun, a software system for the numerical computation with functions, are described. These algorithms allow the construction and manipulation of piecewise smooth functions numerically with machine precision. Breakpoints delimiting subintervals are introduced explicitly, implicitly or automatically, the latter method combining recursive subdivision and edge detection techniques. For interpolation by rational functions with free poles, a novel method is presented. When the interpolation nodes are roots of unity or Chebyshev points the algorithm is particularly simple and relies on discrete Fourier transform matrices, which results in a fast implementation using the Fast Fourier Transform. The method is generalised for arbitrary grids, which requires the construction of polynomials orthogonal on the set of interpolation nodes. The new algorithm has connections with other methods, particularly the work of Jacobi and Kronecker, Berrut and Mittelmann, and Egecioglu and Koc. Computed rational interpolants are compared with the behaviour expected from the theory of convergence of these approximants, and the difficulties due to truncated arithmetic are explained. The appearance of common factors in the numerator and denominator due to finite precision arithmetic is characterised by the behaviour of the singular values of the linear system associated with the rational interpolation problem. Finally, new Remez algorithms for the computation of best polynomial and rational approximations are presented. These algorithms rely on interpolation, for the computation of trial functions, and on Chebfun, for the location of trial references. For polynomials, the algorithm is particularly robust and efficient, and we report experiments with degrees in the thousands. For rational functions, we clarify the numerical issues that affect its application.

To effectively provide services to citizens, local governments have had to be creative. One approach has been the creation of volunteer programs to meet demands and expanding needs. Volunteer programs hold promise for creating meaningful engagement opportunities for citizens. However, limited organizational capacity, inadequate volunteer management practices, and difficulties in maintaining volunteer retention are concerns plaguing local government volunteer programs. Volunteer programs are often structured around a set of best practices thought to be necessary for ensuring the retention of volunteers. To apply best practices across the board would suggest that local government volunteer programs are similar in organizational structure, budget size, amount of citizen engagement, accountability concerns, and that they adopt similar bureaucratic procedures. Using human relations and bureaucratic theories as theoretical frameworks, four research questions are asked and answered: 1) What are the managerial and political challenges in volunteer management and retention for local government volunteer coordinators?, 2) What challenges are local governments' volunteer coordinators facing in using volunteer management practices?, 3) What strategies are helpful in retaining volunteers in local government volunteerism?, and 4) What challenges do local government volunteer coordinators face in engaging citizens? Data collection for this qualitative study was conducted using online surveys and telephone semi-structured interviews. The findings suggest that creating meaningful work for volunteers and coordinating this work with local government managers was an important "best practices" challenge. Although local government volunteer programs also have a mission of engaging citizens, the practices actually used may directly conflict with their mission. Many volunteer management practices are supporting organizational goals rather than supporting the needs of volunteers. The study findings suggest that the best practices used by local governments are not given equal weight and "one size does not fit all." Instead, local governments must prioritize their practices carefully.

Changing weather patterns, the declining social fabric of rural communities, and economic uncertainty increasingly pose challenges to Vermont communities. The socially and environmentally embedded production practices within sustainable agriculture present a potential solution to these problems. In order to make the most of the potential benefits of these practices society must maximize their adoption. This requires an understanding of both farmer adoption of these practices and consumer perceptions of the resulting food products. This thesis contributes two original articles on sustainable agriculture through the analysis of factors driving both farmer adoption and consumer perceptions of products and practices often thought of as sustainable. The first article seeks to understand farmer adoption of climate change best management practices (CCBMPs). Farmer perceptions of risk and profitability of best management practices (BMPs) are key determinants of adoption, which traditional incentive programs like the Environmental Quality Incentives Program (EQIP) attempt to address by providing financial and technical support. To ensure appropriate price points are offered through these programs, regional price structures must be based upon locally established costs. Thus, this article focuses on the economic cost of implementing and maintaining CCBMPs for twelve diverse farms in Vermont. Specifically, three CCBMPs for Vermont are examined: cover cropping, management intensive rotational grazing (MIRG), and riparian buffer strips. Results of a yearlong farmer based data collection process indicate that the average cost for cover cropping is $129.24/acre, for MIRG is $79.82/acre, and for a tree based riparian buffer strip is $807.33/acre. We conclude that existing incentive payments for cover cropping and MIRG are below costs, likely resulting in under-adoption. The second article reports on a study which seeks to understand the factors influencing Vermont consumer perceptions of raw milk safety. While this article makes no assertion regarding the sustainability of raw milk, an association is established between the motivations for raw milk consumption and sustainable agriculture support. Vermonterâ??s appear to be continuing the trend of consuming raw milk at an increasing rate despite continued declarations from local and national public health officials that raw milk is too microbiologically dangerous to justify its consumption. Thus this study was designed to increase understanding of the factors driving consumer perceptions of raw milk safety. A conceptual model was developed to establish potential factors and related questions were incorporated into the 2014 Vermonter Poll. Resulting data were analyzed using a Probit regression analysis. We conclude that observable factors have the greatest influence on perceptions of raw milk safety. Specifically, perceived health benefits, presence of children in the household, and taste all influence perceptions of raw milk safety.