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Measuring Students’ Perceptions of Student Teaching University Supervisors: Scenario-Based Scale Development Using Rasch and Guttman Facet TheoryHolbrook, Kevin Richard January 2022 (has links)
Thesis advisor: Larry H. Ludlow / In the field of teacher education, it is well documented that the most influential part is the clinical component, often referred to as student teaching or the practicum experience (Cochran-Smith, 1991; Darling-Hammond, 2014; Evertson, 1990). During the practicum, there exists a triad of three individuals: a university supervisor, a K-12 classroom teacher (often referred to as the cooperating teacher), and the teacher candidate. While much research has been conducted on teacher candidates and the cooperating teacher role, there has been a lack of research on the role of the university supervisor. The lack of measurement instruments to assess the quality of the university supervisor puts teacher education programs at a disadvantage, both from a programmatic improvement standpoint, as well as meeting accreditation requirements. This dissertation provides an answer to this issue, creating a new instrument that assesses the quality of the university supervisor, from the perspective of teacher candidates. This instrument is constructed under the Rasch-Guttman Scenario (RGS) framework, as most clearly defined by Ludlow, Baez-Cruz, et al. (2020). The RGS framework derives its influence from the works of George Rasch (1960/80) as well as Louis Guttman’s facet theory (Guttman 1954; Guttman 1957). The result is a new scale, entitled the University Supervisor Quality (USQ) scale, consisting of nine scenario items. All nine items include four facets that comprise the construct of university supervisor quality: resourcefulness, constructive feedback, mentorship, and collaboration. The results of this dissertation suggest that the utilization of the RGS framework is successful for developing a scale about university supervisor quality. In addition, the use of cognitive interviews provide valuable insight into the development of scales using the RGS framework. This scale has the potential for use in teacher education programs for evaluating the quality of their supervisors, and to utilize as evidence for accreditation purposes. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Lynch School of Education. / Discipline: Educational Research, Measurement and Evaluation.
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Budgetering inom osäkra miljöer : En kvalitativ studie om budgetering inom elitfotbollsföreningar i Sverige.Olin, Alfred, Barrdahl, David, Stridh, Erik January 2024 (has links)
Bakgrund: Internationella fotbollsklubbar prioriterar ofta ekonomisk vinning, medan svenska klubbar följer 51%-regeln där medlemmarna har beslutsrätt. Svenska elitfotbollsklubbar fungerar mer som ideella organisationer och måste uppfylla krav för elitlicens. Detta arrangemang syftar till att balansera sportsliga och ekonomiska aspekter genom kontinuerlig utvärdering för att hantera risker. Syfte: Syftet med uppsatsen är att undersöka hur svenska elitfotbollsklubbar budgeterar utifrån den osäkra miljö de verkar i. Dessutom ämnar studien att bidra med insikt och förståelse för hur föreningarna hanterar osäkerhet. Metod: Studien har använt kvalitativ metod med ett abduktivt tillvägagångssätt. Sju semistrukturerade intervjuer har genomförts med företrädare från tre fotbollsklubbar i Allsvenskan. Teorin är insamlad från vetenskapliga artiklar samt böcker. Slutsats: Malmö FF, IFK Göteborg och Hammarby IF integrerar sina strategier med budgetprocesser för långsiktiga och kortsiktiga mål. Klubbarna använder iterativ metod i budgetprocessen för anpassningsbarhet. De hanterar osäkerheter unikt; Malmö FF prioriterar långsiktig dominans, IFK Göteborg inkluderar inte intäkter från spelarförsäljningar, och Hammarby IF fokuserar på biljettintäkter och spelartransaktioner. Klubbarna anpassar strategier med scenarioanalyser, exempelvis IFK Göteborgs krisbudget 2023, och strävar efter transparent medlemsengagemang för att balansera förväntningar och ekonomisk verklighet. / Background: International football clubs often prioritize financial gain, while Swedish clubs adhere to the 51% rule where members have decision-making authority. Swedish elite football clubs function more like non-profit organizations and must meet requirements for elite licensing. This arrangement aims to balance sporting and economic aspects through continuous evaluation to manage risks. Purpose: The purpose of the thesis is to examine how Swedish elite football clubs budget in the uncertain environment in which they operate. Additionally, the study aims to provide insight and understanding into how the associations handle uncertainty. Method: The study used a qualitative approach with an abductive method. Seven semi-structured interviews were conducted with representatives from three football clubs in the Allsvenskan. The theory was gathered from scientific articles and books. Conclusion: Malmö FF, IFK Göteborg, and Hammarby IF integrate their strategies with budget processes for both long-term and short-term goals. The clubs use an iterative method in the budget process for adaptability. They handle uncertainties uniquely; Malmö FF prioritizes long-term dominance, IFK Göteborg does not include revenues from player sales, and Hammarby IF focuses on ticket revenues and player transactions. The clubs adapt strategies with scenario analyses, such as IFK Göteborg's crisis budget in 2023, and strive for transparent member engagement to balance expectations and economic reality.
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IEA and Oil : Track record analysis and assessment of oil supply scenarios in WEO 2000-2013Henke, Petter January 2014 (has links)
The World Energy Outlook (WEO), an annual publication from the International Energy Agency (IEA), is often considered to be the most authoritative source of future energy scenarios for policy decision makers. The demand and supply scenarios for oil, one of the most irreplaceable resources in the global energy system, are central in each report. For the last decade, the outlook for oil supply in 2030 in the main IEA scenario has been reduced by almost 20 million barrels per day. The aim of this study is to examine the revisions to the oil supply scenarios, both at global and individual country level, and note if and how the IEA has motivated these revisions. The accuracy of past WEO scenarios is quantified by track record analysis and the latest WEO scenario is assessed in detail in relation to current scientific literature. Finally, implications of the latest WEO scenario for the long term oil supply are assessed. It is noted that the IEA generally motivate upward revisions to their scenarios, while downward revisions are often left unmentioned. Some recent revisions are attributed to the financial crises of 2008 and the largest revision in absolute terms is the gradual downward revision of OPEC production motivated by an underestimation of key producing countries’ will and ability to expand capacity. The track record analysis indicates that the accuracy of the IEA scenarios has increased on a five year prediction basis following the extended methodology applied in the WEO 2008. The analysis also shows that the accuracy of scenarios decrease with time. On a ten year horizon, the mean absolute error for the IEA aggregate ‘World oil supply” was estimated to 8.2%. The WEO2013 ‘New Policies Scenario’, with a time frame of 2012-2035, was assessed using decline and depletion rate analysis, and compared to empirically proven rates. The scenario was found to provide a realistic but optimistic view of the future of oil supply. An alternative scenario, with depletion rates in line with the fastest observed regional rates, resulted in somewhat lower production rates throughout the scenario time frame. A long term extrapolation to year 2100 of the WEO 2013 scenario, based strictly on resource and production data from the WEO reports, indicated that oil supply will reach a peak in 2035 and then enter decline for the remainder of the century. A sensitivity analysis showed that changes to the assumed resource base only moves the peak by a few years, but has a significant effect on the rate of the following decline.
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Models, methods and algorithms for supply chain planningDerrick, Deborah Chippington January 2011 (has links)
An outline of supply chains and differences in the problem types is given. The motivation for a generic framework is discussed and explored. A conceptual model is presented along with it application to real world situations; and from this a database model is developed. A MIP and CP implementations are presented; along with alternative formulation which can be use to solve the problems. A local search solution algorithm is presented and shown to have significant benefits. Problem instances are presented which are used to validate the generic models, including a large manufacture and distribution problem. This larger problem instance is not only used to explore the implementation of the models presented, but also to explore the practically of the use of alternative formulation and solving techniques within the generic framework and the effectiveness of such methods including the neighbourhood search solving method. A stochastic dimension to the generic framework is explored, and solution techniques for this extension are explored, demonstrating the use of solution analysis to allow problem simplification and better solutions to be found. Finally the local search algorithm is applied to the larger models that arise from inclusion of scenarios, and the methods is demonstrated to be powerful for finding solutions for these large model that were insoluble using the MIP on the same hardware.
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Design and architecture of a stochastic programming modelling systemValente, Christian January 2011 (has links)
Decision making under uncertainty is an important yet challenging task; a number of alternative paradigms which address this problem have been proposed. Stochastic Programming (SP) and Robust Optimization (RO) are two such modelling ap-proaches, which we consider; these are natural extensions of Mathematical Pro-gramming modelling. The process that goes from the conceptualization of an SP model to its solution and the use of the optimization results is complex in respect to its deterministic counterpart. Many factors contribute to this complexity: (i) the representation of the random behaviour of the model parameters, (ii) the interfac-ing of the decision model with the model of randomness, (iii) the difficulty in solving (very) large model instances, (iv) the requirements for result analysis and perfor-mance evaluation through simulation techniques. An overview of the software tools which support stochastic programming modelling is given, and a conceptual struc-ture and the architecture of such tools are presented. This conceptualization is pre-sented as various interacting modules, namely (i) scenario generators, (ii) model generators, (iii) solvers and (iv) performance evaluation. Reflecting this research, we have redesigned and extended an established modelling system to support modelling under uncertainty. The collective system which integrates these other-wise disparate set of model formulations within a common framework is innovative and makes the resulting system a powerful modelling tool. The introduction of sce-nario generation in the ex-ante decision model and the integration with simulation and evaluation for the purpose of ex-post analysis by the use of workflows is novel and makes a contribution to knowledge.
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Travelling fires for structural designStern-Gottfried, Jamie January 2011 (has links)
Traditional methods for specifying thermal inputs for the structural fire analysis of buildings assume uniform burning and homogeneous temperature conditions throughout a compartment, regardless of its size. This is in contrast to the observation that accidental fires in large, open-plan compartments tend to travel across floor plates, burning over a limited area at any one time. This thesis reviews the assumptions inherent in the traditional methods and addresses their limitations by proposing a methodology that considers travelling fires for structural design. Central to this work is the need for strong collaboration between fire safety engineers to define the fire environment and structural fire engineers to assess the subsequent structural behaviour. The traditional hypothesis of homogeneous temperature conditions in postflashover fires is reviewed by analysis of existing experimental data from wellinstrumented fire tests. It is found that this assumption does not hold well and that a rational statistical approach to fire behaviour could be used instead. The methodology developed in this thesis utilises travelling fires to produce more realistic fire scenarios in large, open-plan compartments than the conventional methods that assume uniform burning and homogeneous gas phase temperatures which are only applicable to small compartments. The methodology considers a family of travelling fires that includes the full range of physically possible fire sizes iv within a given compartment. The thermal environment is split into two regions: the near field (flames) and the far field (smoke away from the flames). Smaller fires travel across a floor plate for long periods of time with relatively cool far field temperatures, while larger fires have hotter far field temperatures but burn for shorter durations. The methodology is applied to case studies showing the impact of travelling fires on generic concrete and steel structures. It is found that travelling fires have a considerable impact on the performance of these structures and that conventional design approaches cannot automatically be assumed to be conservative. The results indicate that medium sized fires between 10% and 25% of the floor area are the most onerous for a structure. Detailed sensitivity analyses are presented, showing that the structural design and fuel load have a larger impact on structural behaviour than any numerical or physical parameter required for the methodology. This thesis represents a foundation for using travelling fires for structural analysis and design. The impact of travelling fires is critical for understanding true structural response to fire in modern, open-plan buildings. It is recommended that travelling fires be considered more widely for structural design and the structural mechanics associated with them be studied in more detail. The methodology presented in this thesis provides a key framework for collaboration between fire safety engineers and structural fire engineers to achieve these aims.
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Methodological Issues in Malingering Research: The Use of Simulation DesignsGillard, Nathan D. 12 1900 (has links)
The accurate determination of malingering relies on the use of validated and clinically relevant assessment measures. Simulation design is the most often-used research design to accomplish this. However, its external validity is sometimes questioned. The goal of the thesis was to systematically evaluate these major elements: situation, incentives, and coaching. The situation in simulation studies can vary from relevant (academic failure in a college population) to irrelevant (capital murder) for the samples being studied. Incentives refer to the external motivation given to improve simulators' performance and can be positive (extra credit and monetary reward) or negative (extra time and effort). Finally, coaching refers to whether the participant receives any information on detection strategies that are designed to identify feigners. Using a large undergraduate sample in a factorial design, results indicate that a scenario familiar to the participants generally improved the believability of their responses. Coaching also improved the ability to feign convincingly, while incentive type was not associated with any change in scores. The implications of these findings for future research designs and the connection to practice are discussed.
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Scénářové stromy v úlohách stochastického programování / Scenario trees in stochastic programming problemsMalá, Alena January 2014 (has links)
This thesis deals with multi-stage stochastic linear programming and its ap- plictions in the portfolio selection problem. It presents several models of invest- ment planning, the emphasis is on the basic model with transaction costs and risk adjusted model for every investment level. Random returns entering the above models are modelled by the scenario trees which are generated using the moment- matching method. The thesis presents the optimal investment strategy for each model. It then examines distance of optimal values of objective functions in de- pendence on the nested distance of these generated trees. All calculations were performed using Mathematica software version 9. 1
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Proposta de modelo de exposição humana à saxitoxina em águas de recreação e de abastecimento público do reservatório Itupararanga / Proposal of a model of human exposure to saxitoxin in recreational waters and public supply of the Itupararanga reservoirLuciana Haipek Mosolino Lerche 04 July 2018 (has links)
O aporte artificial de nutrientes nos ambientes aquáticos tem favorecido a incidência de florações de cianobactérias, causando impactos na qualidade da água e colocando em risco a saúde humana. O gênero de cianobactéria Cylindrospermopsis, amplamente distribuído em água doce pelo mundo, é capaz de produzir diversas cianotoxinas, dentre elas saxitoxina e análogos. O objetivo deste trabalho foi elaborar um modelo de exposição referente à ingestão de água contaminada por saxitoxina e análogos através da recreação de contato primário e do consumo de água. Os dados de densidade de células de Cylindrospermopsis e de concentrações de saxitoxina e análogos na água bruta foram obtidos da Rede de Monitoramento de Qualidade de Águas Superficiais da CETESB (2015 e 2016) do reservatório Itupararanga. O modelo conceitual de exposição e o cálculo da ingestão diária crônica de saxitoxina e análogos consideraram: concentrações máxima e mínima de saxitoxina e análogos encontradas na água bruta do reservatório, vias de exposição, população exposta, taxa de ingestão de água, frequência e duração da exposição, peso corporal para adultos (maiores de 21 anos) e crianças (menores de 5 anos), para cenários de exposição relativos à recreação de contato primário e consumo de água potável. Os valores de células de cianobactérias estiveram entre 2.216 e 203.082 céls.mL-1 e as concentrações de saxitoxina e análogos estiveram entre 0,04 e 0,37 µg equivalente STX..L-1. Os resultados obtidos na análise da água bruta do reservatório, estiveram abaixo do valor estabelecido na legislação brasileira para água potável (3 µg equivalente STX.L-1), mas não atenderiam as especificações adotadas por Oregon e Ohio (0,3 µg equivalentes STX.L-1) e à proposta em discussão no Comitê Permanente para Gestão Integrada da Qualidade da Água destinada ao Consumo Humano no Estado de São Paulo (0,13 µg equivalente STX.L-1), indicando a possibilidade da ocorrência de efeito adverso à saúde em grupos sensíveis que utilizem água do reservatório, dependendo da eficiência de remoção dessas cianotoxinas no processo de tratamento. Os valores de ingestão diária crônica estimados, para recreação, variaram de 2,55 x 10-6 a 1,08 x 10-4 µg equivalente STX. kg-1.dia-1 (adultos) e 2,78 x 10-9 a 4,35 x 10-4 µg equivalente STX. kg-1.dia-1 (crianças). Para ingestão de água potável, esses valores variaram de 2,5 x 10-4 a 1,47 x 10-2 µg equivalente STX. kg-1.dia-1 (adultos) e 5,36 x 10-5 a 2,55 x 10-2 µg equivalente STX. kg-1.dia-1 (crianças). Esses valores indicaram que as crianças estão mais expostas que os adultos, fato preocupante, pois elas são mais sensíveis aos efeitos de substâncias tóxicas, e apesar de estudos indicarem efeitos da saxitoxina em cultura de células neurais, sua capacidade de atravessar a barreira hematoencefálica e de causar danos cognitivos em ratos, os efeitos da exposição crônica em humanos ainda são desconhecidos. Não foi possível estimar os riscos à saúde da população exposta à saxitoxina e análogos, pela falta de dados na literatura, porém o modelo de exposição proposto é um avanço para a identificação de lacunas para a condução da avaliação de risco à saúde humana considerando a exposição crônica. / The artificial enrichment of nutrients in aquatic environments has favored the incidence of cyanobacteria blooms, causing impacts on water quality and putting human health at risk. The genus of cyanobacteria Cylindrospermopsis, widely distributed throughout the world in freshwater environments, is able to produce cianotoxin, among them saxitoxin and its analogues. The objective of this work was to elaborate a model of exposure referring to the ingestion of water contaminated by saxitoxin and analogues through recreation of primary contact and water consumption. Cylindrospermopsis cell density and saxitoxin and analogues concentrations in surface water were obtained from the CETESB Surface Water Quality Monitoring Network for the Itupararanga reservoir in 2015 and 2016. The development of the conceptual model of exposure and the calculation of the chronic daily intake of saxitoxin and analogues, considered: maximum and minimum concentrations of saxitoxin and analogues found in the raw water of the reservoir, route of exposure, exposed population, rate of water intake, frequency and duration of exposure, body weight for adults (over 21 years) and children (under 5 years), for exposures scenarios concerning recreation of primary contact and consumption of drinking water. The values of cyanobacteria cells were between 2,216 and 203,082 cells.L-1 and the concentrations of saxitoxin and analogues were between 0.04 and 0.37 µg STX equivalent. L-1. The comparison of these variables indicated a significant positive correlation between them. The results obtained in the raw water analysis of the reservoir were below the value established in Brazilian legislation for drinking water (3 µg equivalent STX.L-1), but would not meet the specifications adopted by US states Oregon and Ohio (0.3 µg equivalents.L-1) and the proposed value for the Standing Committee for Integrated Water Quality Management for Human Consumption in the State of São Paulo (0,13 µg equivalent STX.L-1), indicating the possibility of adverse health effects in sensitive groups using water from the reservoir. Estimated chronic daily intake values, for recreation, ranged from 2.55 x 10-6 to 1.08 x 10-4 µg STX equivalent. kg-1.day-1 (adults) and 2.78 x 10-9 to 4.35 x 10-4 µg STX equivalent. kg-1.day-1 (children). For water intake, these values ranged from 2.5 x 10-4 to 1.47 x 10-2 µg STX equivalent. kg-1 day-1 (adults) and 5.36 x 10-5 to 2.55 x 10-2 µg STX equivalent. kg-1. day-1 (children). These values indicated that children are more exposed than adults, a worrying fact because they are generally more sensitive to the effects of toxic substances than adults, and although studies indicate that saxitoxin was able to cross the blood brain barrier and to cause cognitive damage in rats, as well as changes in neural cell cultures, the effects of chronic exposure in humans are still unknown. It was not possible to estimate the health risks of the population exposed to saxitoxin and the like, due to the lack of data in the literature, but the proposed exposure model is an advance for the identification of gaps for conducting the human health risk assessment considering the exposure chronic.
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Proposta de modelo de exposição humana à saxitoxina em águas de recreação e de abastecimento público do reservatório Itupararanga / Proposal of a model of human exposure to saxitoxin in recreational waters and public supply of the Itupararanga reservoirMosolino Lerche, Luciana Haipek 04 July 2018 (has links)
O aporte artificial de nutrientes nos ambientes aquáticos tem favorecido a incidência de florações de cianobactérias, causando impactos na qualidade da água e colocando em risco a saúde humana. O gênero de cianobactéria Cylindrospermopsis, amplamente distribuído em água doce pelo mundo, é capaz de produzir diversas cianotoxinas, dentre elas saxitoxina e análogos. O objetivo deste trabalho foi elaborar um modelo de exposição referente à ingestão de água contaminada por saxitoxina e análogos através da recreação de contato primário e do consumo de água. Os dados de densidade de células de Cylindrospermopsis e de concentrações de saxitoxina e análogos na água bruta foram obtidos da Rede de Monitoramento de Qualidade de Águas Superficiais da CETESB (2015 e 2016) do reservatório Itupararanga. O modelo conceitual de exposição e o cálculo da ingestão diária crônica de saxitoxina e análogos consideraram: concentrações máxima e mínima de saxitoxina e análogos encontradas na água bruta do reservatório, vias de exposição, população exposta, taxa de ingestão de água, frequência e duração da exposição, peso corporal para adultos (maiores de 21 anos) e crianças (menores de 5 anos), para cenários de exposição relativos à recreação de contato primário e consumo de água potável. Os valores de células de cianobactérias estiveram entre 2.216 e 203.082 céls.mL-1 e as concentrações de saxitoxina e análogos estiveram entre 0,04 e 0,37 µg equivalente STX..L-1. Os resultados obtidos na análise da água bruta do reservatório, estiveram abaixo do valor estabelecido na legislação brasileira para água potável (3 µg equivalente STX.L-1), mas não atenderiam as especificações adotadas por Oregon e Ohio (0,3 µg equivalentes STX.L-1) e à proposta em discussão no Comitê Permanente para Gestão Integrada da Qualidade da Água destinada ao Consumo Humano no Estado de São Paulo (0,13 µg equivalente STX.L-1), indicando a possibilidade da ocorrência de efeito adverso à saúde em grupos sensíveis que utilizem água do reservatório, dependendo da eficiência de remoção dessas cianotoxinas no processo de tratamento. Os valores de ingestão diária crônica estimados, para recreação, variaram de 2,55 x 10-6 a 1,08 x 10-4 µg equivalente STX. kg-1.dia-1 (adultos) e 2,78 x 10-9 a 4,35 x 10-4 µg equivalente STX. kg-1.dia-1 (crianças). Para ingestão de água potável, esses valores variaram de 2,5 x 10-4 a 1,47 x 10-2 µg equivalente STX. kg-1.dia-1 (adultos) e 5,36 x 10-5 a 2,55 x 10-2 µg equivalente STX. kg-1.dia-1 (crianças). Esses valores indicaram que as crianças estão mais expostas que os adultos, fato preocupante, pois elas são mais sensíveis aos efeitos de substâncias tóxicas, e apesar de estudos indicarem efeitos da saxitoxina em cultura de células neurais, sua capacidade de atravessar a barreira hematoencefálica e de causar danos cognitivos em ratos, os efeitos da exposição crônica em humanos ainda são desconhecidos. Não foi possível estimar os riscos à saúde da população exposta à saxitoxina e análogos, pela falta de dados na literatura, porém o modelo de exposição proposto é um avanço para a identificação de lacunas para a condução da avaliação de risco à saúde humana considerando a exposição crônica. / The artificial enrichment of nutrients in aquatic environments has favored the incidence of cyanobacteria blooms, causing impacts on water quality and putting human health at risk. The genus of cyanobacteria Cylindrospermopsis, widely distributed throughout the world in freshwater environments, is able to produce cianotoxin, among them saxitoxin and its analogues. The objective of this work was to elaborate a model of exposure referring to the ingestion of water contaminated by saxitoxin and analogues through recreation of primary contact and water consumption. Cylindrospermopsis cell density and saxitoxin and analogues concentrations in surface water were obtained from the CETESB Surface Water Quality Monitoring Network for the Itupararanga reservoir in 2015 and 2016. The development of the conceptual model of exposure and the calculation of the chronic daily intake of saxitoxin and analogues, considered: maximum and minimum concentrations of saxitoxin and analogues found in the raw water of the reservoir, route of exposure, exposed population, rate of water intake, frequency and duration of exposure, body weight for adults (over 21 years) and children (under 5 years), for exposures scenarios concerning recreation of primary contact and consumption of drinking water. The values of cyanobacteria cells were between 2,216 and 203,082 cells.L-1 and the concentrations of saxitoxin and analogues were between 0.04 and 0.37 µg STX equivalent. L-1. The comparison of these variables indicated a significant positive correlation between them. The results obtained in the raw water analysis of the reservoir were below the value established in Brazilian legislation for drinking water (3 µg equivalent STX.L-1), but would not meet the specifications adopted by US states Oregon and Ohio (0.3 µg equivalents.L-1) and the proposed value for the Standing Committee for Integrated Water Quality Management for Human Consumption in the State of São Paulo (0,13 µg equivalent STX.L-1), indicating the possibility of adverse health effects in sensitive groups using water from the reservoir. Estimated chronic daily intake values, for recreation, ranged from 2.55 x 10-6 to 1.08 x 10-4 µg STX equivalent. kg-1.day-1 (adults) and 2.78 x 10-9 to 4.35 x 10-4 µg STX equivalent. kg-1.day-1 (children). For water intake, these values ranged from 2.5 x 10-4 to 1.47 x 10-2 µg STX equivalent. kg-1 day-1 (adults) and 5.36 x 10-5 to 2.55 x 10-2 µg STX equivalent. kg-1. day-1 (children). These values indicated that children are more exposed than adults, a worrying fact because they are generally more sensitive to the effects of toxic substances than adults, and although studies indicate that saxitoxin was able to cross the blood brain barrier and to cause cognitive damage in rats, as well as changes in neural cell cultures, the effects of chronic exposure in humans are still unknown. It was not possible to estimate the health risks of the population exposed to saxitoxin and the like, due to the lack of data in the literature, but the proposed exposure model is an advance for the identification of gaps for conducting the human health risk assessment considering the exposure chronic.
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