Transformations in the economy have led to changes in employment practices that can create a mismatch between parents’ work schedules and family routines. At the same time, approaches to child-rearing have become more time-intensive, with expectations of increased parental involvement in all aspects of children’s lives compared to previous generations. Mothers are subject to a more intensified maternal role and for fathers, the provider role is no longer sufficient. There are strong social pressures for more active participation in children’s lives and to nurture greater emotional connectivity in the parent-child relationship. These transformations in parenting and employment practices have contributed to a situation where parents now report increased levels of time pressure and greater dissatisfaction with the balance between work and the rest of their lives. The purpose of this study was to develop a broader understanding of how mothers and fathers with school-age children allocate their time, how it varies by household composition, season of the year, and work schedule, and how time use is related to subjective well-being. Given the role that leisure may play in creating a more satisfactory work-life balance, special attention was given to the amount of time available for leisure, with whom this time was spent and the relationship to quality of life. The gender relations perspective provided a theoretical framework since role expectations and experiences of parenthood differ for mothers and fathers. By considering individual, interpersonal, institutional and socio-historical levels of influence, patterns of behaviour may be better understood within the Canadian social context. This study is a secondary analysis of the 2005 Canadian General Social Survey, Cycle 19. Using a sub-sample of 2,062 parents of school-age children (ages 5-17 years), patterns of time use and perceptions of quality of life were assessed and compared by gender according to household composition, season of the school year, work schedule and flexible work option. Work schedules were categorized as traditional (daytime, no weekends), non-standard (evening, weekend and rotating shifts) and irregular (unpredictable, with “on call”, casual, or other irregular patterns). Gender inequality in the allocation of time to important life spheres remained substantial even when faced with very complex challenges in coordinating employment arrangements, family routines, and the school year schedule. With the exception of single fathers, men spent more time on employment-related activities than women regardless of work schedule, while women continued to perform greater amounts of domestic and child care activities. Combined workloads of paid and unpaid labour were significantly different only among single mothers and fathers. For married or cohabitating parents, the distribution of paid and unpaid labour was asymmetrical but the combined workload was not significantly different. Fathers continued to be privileged with greater amounts of leisure time. This was especially noticeable for men with non-standard work schedules and fathers of teenage children. Seasonal differences in time use indicated that women’s routines were more linked to the school year than men’s because of their greater child care responsibilities. When irregular or non-standard schedules were in place that could create more optimal conditions for reconsidering time allocation, parents still followed activity patterns that reproduced traditional gender roles. For women, non-standard schedules were the most detrimental to quality of life, whereas for men irregular schedules decreased well-being. Flexible schedules also perpetuated inequality in the distribution of paid work, unpaid work and leisure although quality of life actually improved for women. This improved quality of life may be attributable to more time spent on activities with physical health benefits or increased options for daily schedules, but it also leads to questions about how much control mothers actually have over their time and whether they recognize or care to challenge the inequalities that persist in the distribution of labour and leisure. Quality of life was diminished by conditions that contributed to a deviation from traditional role expectations. Some of these included not having a partner, women’s work schedules that conflicted with other family members, and for men, having an irregular and unpredictable work schedule. Since these conditions are characteristic of a sizable minority of Canadians parents, their experiences should not be dismissed but rather given greater attention. Additionally, future discussions of work-life integration should consider access to leisure since time for leisure was shown to contribute to parents’ quality of life. The gender relations perspective proved to be helpful in interpreting and understanding the dynamics of time use and behaviour. The four levels of interaction were highly interconnected, but changing institutional conditions such as employment schedules did not lead to greater equality. Instead, non-traditional work schedules widened the gender gap, particularly for child care and domestic activities. Dominant parenting practices were shown to be so deeply imbedded that stereotypical patterns remained a prevailing force guiding men’s and women’s daily activities. The GSS data, despite some limitations, provided considerable insight into the effect of parents’ employment and gender on time use and well-being. The findings of this study underscore the relevance of considering multiple levels of influence when assessing parenting practices, gendered behaviour, and quality of life for employed parents.

This study investigated effects of commercially available picture activity schedules (PAS) and system of least prompts (SLP) to teach recreation skills to four high school students with Autism Spectrum Disorders and intellectual disabilities using Lego sets. Results were evaluated through a multiple probe across participants design and indicate that a combination of PAS and SLP was effective for teaching the students to build Lego sets. All students improved their ability to build and were able to generalize the skill to novel sets after the completion of intervention. Limitations and implications for future practioners are discussed.

Delivering health care services in an efficient and effective way has become a great challenge for many countries due to the aging population worldwide, rising health expenses, and increasingly complex healthcare delivery systems. It is widely recognized that models and analytical tools can aid decision-making at various levels of the healthcare delivery process, especially when decisions have to be made under uncertainty. This thesis employs stochastic models to improve decision-making under uncertainty in two specific healthcare settings: inpatient flow management and infectious disease modeling. In Part I of this thesis, we study patient flow from the emergency department (ED) to hospital inpatient wards. This line of research aims to develop insights into effective inpatient flow management to reduce the waiting time for admission to inpatient wards from the ED. Delayed admission to inpatient wards, also known as ED boarding, has been identified as a key contributor to ED overcrowding and is a big challenge for many hospitals. Part I consists of three main chapters. In Chapter 2 we present an extensive empirical study of the inpatient department at our collaborating hospital. Motivated by this empirical study, in Chapter 3 we develop a high fidelity stochastic processing network model to capture inpatient flow with a focus on the transfer process from the ED to the wards. In Chapter 4 we devise a new analytical framework, two-time-scale analysis, to predict time-dependent performance measures for some simplified versions of our proposed model. We explore both exact Markov chain analysis and diffusion approximations. Part I of the thesis makes contributions in three dimensions. First, we identify several novel features that need to be built into our proposed stochastic network model. With these features, our model is able to capture inpatient flow dynamics at hourly resolution and reproduce the empirical time-dependent performance measures, whereas traditional time-varying queueing models fail to do so. These features include unconventional non-i.i.d. (independently and identically distributed) service times, an overflow mechanism, and allocation delays. Second, our two-time-scale framework overcomes a number of challenges faced by existing analytical methods in analyzing models with these novel features. These challenges include time-varying arrivals and extremely long service times. Third, analyzing the developed stochastic network model generates a set of useful managerial insights, which allow hospital managers to (i) identify strategies to reduce the waiting time and (ii) evaluate the trade-off between the benefit of reducing ED congestion and the cost from implementing certain policies. In particular, we identify early discharge policies that can eliminate the excessively long waiting times for patients requesting beds in the morning. In Part II of the thesis, we model the spread of influenza pandemics with a focus on identifying factors that may lead to multiple waves of outbreak. This line of research aims to provide insights and guidelines to public health officials in pandemic preparedness and response. In Chapter 6 we evaluate the impact of seasonality and viral mutation on the course of an influenza pandemic. In Chapter 7 we evaluate the impact of changes in social mixing patterns, particularly mass gatherings and holiday traveling, on the disease spread. In Chapters 6 and 7 we develop agent-based simulation models to capture disease spread across both time and space, where each agent represents an individual with certain socio-demographic characteristics and mixing patterns. The important contribution of our models is that the viral transmission characteristics and social contact patterns, which determine the scale and velocity of the disease spread, are no longer static. Simulating the developed models, we study the effect of the starting season of a pandemic, timing and degree of viral mutation, and duration and scale of mass gatherings and holiday traveling on the disease spread. We identify possible scenarios under which multiple outbreaks can occur during an influenza pandemic. Our study can help public health officials and other decision-makers predict the entire course of an influenza pandemic based on emerging viral characteristics at the initial stage, determine what data to collect, foresee potential multiple waves of attack, and better prepare response plans and intervention strategies, such as postponing or cancelling public gathering events.

The primary aim of this survey is to: * explore whether there is potential for job-sharing in the South African labour market; * * describe the characteristics of potential job-sharers and to explain why Job-sharing would be an appropriate and feasible solution to unemployment, massive retrenchments, poor quality ofwork life (QWL) and low worker productivity Job-sharing has been used in many developed countries to address a variety of problems at the individual, organisational and national level. These include allowing workers to have a balance between their work and non-work life; to increase worker productivity and QWL and to increase employment opportunities. The literature survey affirms that these problems are prevalent in Africa as a whole and in South Africa specifically. The survey results reveal that the environment in South is Africa is conducive to jobsharing and that slightly over one third of the workers and organisations and two thirds of the jobseekers are willing to job-share. The results of this study also reveals that QWL, productivity and unemployment does influence the willingness to job-share and that approximately 80% of the employees would rather either job-share, work-share or opt for some other alternative than to have retrenchments. Thus by implication, job-sharing would address the problems relating to poor QWL, low worker productivity, fewer employment opportunities, as well as massive retrenchments in South Africa. The study has also explored possible reasons and obstacles to job-sharing and found that whether these are perceived as significantly important or not, depends on whether one is an employer, employee or job-seeker . The job-seekers feel more than others, that there is no reason insurmountable or obstacle preventing the introduction of job-sharing by which to avert their unemployed status. There are also differences in willingness to job-share among subgroups with regard to the industry, area of work, position held in the organisation and the availability of job-sharing positions in the organisation. This thesis reports that there is potential for job-sharing in the South African labour market, to address a variety of problems pertaining to workers, organisations, job-seekers and, therefore, the whole nation at large. / Business Management / D.B.L.

Made available in DSpace on 2016-06-02T20:30:11Z (GMT). No. of bitstreams: 1 6760.pdf: 2504221 bytes, checksum: 45e64948f4a0d4d5a9beeab79feef1f1 (MD5) Previous issue date: 2015-03-13 / Financiadora de Estudos e Projetos / Food with high sugar concentration exhibits relation with impulsive eating behavior and obesity. This research investigated the effect of different rates of reinforcement and compositions of food, traditional or light, on the choice responses pattern of four undergraduate students. Those foods have similar organoleptic characteristics and different sugar concentration. One study, whith three phases was did, in all of them, two stimuli representing the initial links of a chain-concurrent schedule were presented, simultaneously, to the participants in a computer screen. Choice response in the initial links was followed by the second link of the chain-concurrent schedule. In Phase 1, response in FR1 on the second link was followed by the delivering, in both alternatives, of juice samples with the same composition, flavor and magnitude, an inter-trial interval and another trial. In Phase 2, response in FR1 on the second link was followed by the delivering of samples of traditional juice composition on one terminal link of the chain-concurrent schedule or light juice composition on another terminal link of the chain-concurrent schedule, an inter-trial interval and another trial. In Phase 3, was added primarily contextual stimuli consistent with the structural arrangement indicating which composition would have the juice samples available for each alternative and later this contextual stimuli became inconsistent with the structural arrangement. The sessions presented varied in time. The maximum duration was 10 minutes and occurred, on average, three times a week. The results showed that human subjects have difficult to exhibit maximization in chain-concurrent schedule, have good sensitivity to the different reinforcement rates in chain-concurrent schedule and concentrations of sugar in samples of traditional and light juices composition. / Alimentos com alta concentração de açúcar apresentam relação com comportamento alimentar impulsivo e obesidade. Esta pesquisa investigou o efeito que diferentes taxas de reforçamento e composições de alimentos, tradicional ou light, exerciam no comportamento de escolhas de quatro universitários. Tais alimentos apresentavam características organolépticas similares e diferiam apenas quanto à concentração de açúcar. Um estudo, contendo três fases, foi realizado com dois estímulos representando os elos iniciais de esquemas de reforçamento concorrentes encadeados apresentados, simultaneamente, aos participantes na tela do computador. Respostas nos elos iniciais foram seguidas pelo segundo elo do esquema encadeado. Na Fase 1, respostas em FR1 no segundo elo foram seguidas pela apresentação, em ambas as alternativas, de amostras de sucos de mesma quantidade, mesmo sabor e mesma composição, um intervalo intertentativas e o início de uma nova tentativa. Na Fase 2, respostas em FR1 no segundo elo foram seguidas pela apresentação de amostras de sucos de mesma quantidade, mesmo sabor, porém de composição tradicional em um elo terminal e light no outro elo terminal, um intervalo intertentativas e o início de uma nova tentativa. Na Fase 3, foram adicionados, primeiramente, dois estímulos contextuais consistentes com o arranjo estrutural, indicando a composição das amostras de suco que seriam disponibilizadas em cada alternativa. Posteriormente, os estímulos contextuais se tornaram inconsistentes com o arranjo estrutural, indicando erroneamente a composição das amostras de suco que seriam disponibilizadas em cada alternativa. As sessões ocorreram em média três vezes na semana e apresentaram tempo variado, tendo 10 minutos de duração a mais longa. Os resultados mostram que humanos têm dificuldades de emitir padrão maximizado de escolhas em esquemas de reforçamento concorrentes encadeados, que apresentam alta sensibilidade em relação às diferentes taxas de reforço dos esquemas concorrentes e discriminam as concentrações de açúcar de amostras de sucos de composição tradicional e light.

Ensaios pioneiros sobre o manejo de florestas tropicais, no final da década de 70, foram executados na Floresta Nacional (FLONA) do Tapajós; e atualmente surge a oportunidade de se iniciar os estudos relativos ao segundo ciclo de corte. Nisto, áreas experimentais em que a exploração inicial foi intensiva apresentam mudanças na cobertura vegetal, com abundância de espécies menos conhecidas ou não comerciais, sendo então necessário analisar tecnologicamente a madeira dessas espécies com o intuito de inseri-las no mercado. Visando colaborar nesse sentido, o presente trabalho teve como objetivo principal caracterizar tecnologicamente e elaborar programas de secagem para as madeiras de Acariquarana (Rinorea guianensis), Breu (Protium apiculatum) e Urucu da mata (Bixa arborea); espécies com alta densidade populacional na área do segundo ciclo de corte na FLONA Tapajós. Para tal, abateu-se cinco árvores de cada espécie, sendo coletado material tanto para a identificação botânica como para a caracterização anatômica, ensaios físico-mecânicos e elaboração dos programas de secagem, além destes foram realizados testes estatísticos de correlação canônica para identificar as associações entre as características estudadas. Com base nos resultados, a madeira das espécies Rinorea guianensis e Protium apiculatum apresentaram características anatômicas semelhantes às encontradas em literatura ao nível de gênero e, Bixa arborea para o nível de espécie. Em relação às principais propriedades físico-mecânicas, as madeiras de Acariquarana, Breu e Urucu possuem densidade básica de, respectivamente, 0,78; 0,51 e 0,27 g/cm³; e com Módulo de Ruptura (MOR) na flexão estática de 147,98; 79,10 e 34,06 Mpa, na mesma ordem. Em comparação com espécies já comercializadas, a espécie Rinorea guianensis (Acariquarana) pode ser indicada para construção civil, móveis, ferramentas, além de torneados e chapas; a espécie Protium apiculatum (Breu) pode ser usada na construção civil, embalagens, caixas, venezianas, para decoração, móveis e compensados e, Bixa arborea (Urucu da mata) pode ser indicada para molduras, palito de fósforo, compensados, laminados, divisórias internas, engradados, brinquedos, aeromodelismo, além de produção de papel. Foi possível a indicação de programas de secagem específicos para as madeiras de cada uma das espécies estudadas, os quais se mostraram coerentes com as indicações encontradas em literatura para espécies já comercializadas e com características semelhantes às das espécies em estudo. Com relação à analise das correlações canônicas ao nível de 1% de probabilidade entre as propriedades das madeiras observa-se que madeiras de maior frequência e espessura do raio e parede celular de menor espessura estão associadas a madeiras de alta contração tanto tangencial como radial, e baixa densidade básica; madeiras de maior frequência e espessura do raio e com paredes menos espessas estão associadas a madeiras de elevado módulo de ruptura no ensaio de flexão estática e menor módulo de ruptura no ensaio de compressão paralela; madeiras com paredes mais espessas e menor espessura dos raios estão associadas a madeiras de maior módulo de ruptura no ensaio de compressão paralela e menor módulo de ruptura no ensaio de flexão estática; madeiras com raios mais espessos e parede menos espessa estão associados a madeiras de baixo nível de colapso e elevado nível de rachadura. / Pioneering trials on management of tropical forests, in the 70s, were executed in the Tapajós National Forest (FLONA); and presently appears the opportunity to begin the studies for the second cutting cycle. However, experimental areas where initial exploration was intensive present changes in the forest composition, with abundance of lesser-known or non commercial species; being necessary technological analysis of these species lumber to insert it in the market. In order to contribute in this direction, the present work aimed the technological characterization and the development of drying programs for woods of Acariquarana (Rinorea guianensis), Breu (Protium apiculatum) and Urucu da mata (Bixa arborea); species with high population density in areas of second cutting cycle in the Tapajós National Forest. For this, the material was collected for botanical identification and for anatomical characterization, physical and mechanical testing and development of drying programs. The wood of Acariquarana presents some distinct growth rings, straight grain, very large vessels, solitary to multiple, intervascular switches pit, garnished, long fibers with thick cell wall, not septate; Axial parenchyma scanty paratracheal, heterogeneous rays, multiseriate, numerous and the presence of parenchymatical crystals. The wood of Breu has distinct growth rings, crossed grain, big vessels, solitary to multiple, diffuse porosity, intervascular switches pit, garnished, medium-wall fibers, septate, paratracheal vasicentric axial parenchyma, heterogeneous rays, multiseriate, numerous. Wood of Urucu da mata presents distinct growth rings, straight grain, big vessels, diffuse porosity, intervascular switches pit, garnished, thin-walled fibers, septate, axial parenchyma diffuse apotracheal, storied rays, heterogeneous, multiseriates and numerous. Regarding the main physical and mechanical properties the wood of Acariquarana, Breu and Urucu have basic density of, respectively, 0,78; 0,51 and 0,27 g/cm³; and with Module of Rupture (MOR) in static bending of 147,98; 79,10 and 34,06 MPa, in the same order. Compared to species already marketed, Rinorea guianensis (Acariquarana) may be indicated for construction, furniture, tools, turned and plates; Protium apiculatum (Breu) may be used in construction, packages, boxes, blinds, decorating parts, furniture and plywood, and Bixa arborea (Urucu da mata) may be indicated for frames, safety match, plywood, laminates, crates, toys, model airplanes, as well to paper production. It was possible to indicate specific kiln schedules for each one of the studied species lumber, which demonstrated consistent with the information found in literature for species already on the market and with similar characteristics to the studied species.

Os estudos de bioequivalência são realizados em humanos, por meio da administração dos medicamentos em estudo pela mesma via extravascular, sob condições experimentais padronizadas, seguida pela determinação das concentrações plasmáticas do fármaco em função do tempo. Nestes estudos considera-se que curvas estatisticamente semelhantes de decaimento sanguíneo de fármacos produzem o mesmo resultado em termos de eficácia e segurança. A partir das curvas de concentração em função do tempo obtidas, determinam-se os parâmetros farmacocinéticos Cmax, tmax e ASC. A bioequivalência entre dois produtos é estabelecida por meio do IC 90%, que deve estar entre 80 a 125% para os parâmetros farmacocinéticos Cmax e ASC. O cronograma de coleta de amostras biológicas é um dos aspectos mais críticos no planejamento de estudos de bioequivalência, pois este afeta diretamente a determinação dos parâmetros farmacocinéticos utilizados na avaliação da bioequivalência. Outro aspecto importante relacionado a este tipo de estudo é a diferença de teor entre os produtos a serem submetidos ao estudo de bioequivalência, que segundo a legislação brasileira vigente, deve ser menor ou igual a 5%. Neste trabalho foram avaliados diferentes cronogramas de coleta de amostras sangue, avaliando-se o impacto destes no resultado final de um estudo de bioequivalência e, além disso, a influência da diferença de teor de fármaco entre dois produtos que levaria à bioinequivalência também foi investigada. Para tanto simulações matemáticas e um estudo in vivo foram conduzidos. O fármaco modelo escolhido foi a cefadroxila, por apresentar características farmacocinéticas e farmacodinâmicas ideais. O programa Microsoft Office Excel 2003 foi utilizado para simular as concentrações plasmáticas e determinar o IC 90%. As simulações foram feitas por meio de dois modelos: modelo baseado em máximos e mínimos de parâmetros farmacocinéticos, e modelo baseado em coeficientes de variação intra e inter-individuais do fármaco. Dez diferentes doses, entre -10% a 20% da dose referência, e 6 cronogramas de coleta foram avaliados. O estudo in vivo foi realizado com quatro doses diferentes de cefadroxila. A bioequivalência entre as doses e em diferentes cronogramas de coleta foi avaliada em 24 voluntários sadios do sexo masculino. Os voluntários receberam as quatro doses do estudo em desenho cruzado, em quatro períodos e quatro seqüências, com washout de 7 dias entre as doses. As concentrações plasmáticas de cefadroxila, até 8 horas após a administração, foram determinadas por cromatografia líquida de alta eficiência com detecção DAD. Os parâmetros farmacocinéticos tmax, Cmax e AUC0-t foram determinados nas diferentes doses e cronogramas de coleta, sendo que o critério para estabelecer-se a bioequivalência foi baseada nos resultados do IC 90% dos parâmetros farmacocinéticos Cmax e AUC0-t. Os resultados obtidos nas simulações mostraram boa correlação com os dados reais obtidos a partir de estudos in vivo. As simulações baseadas em coeficientes de variação intra e inter-individuais descreveram melhor os resultados observados no estudo in vivo. De acordo com os resultados obtidos no estudo in vivo pode-se concluir que cronogramas de coletas com menos amostras são tão eficientes quanto cronogramas de coletas com mais amostras, desde que o tempo de tmax esteja incluído. Em relação ao teor de fármaco, concluiu-se que dois produtos com diferença de teor menor ou igual a 11% ainda são bioequivalentes e que diferença maior ou igual a 14% resultam em bioinequivalência. Observou-se ainda que o parâmetro farmacocinético ASC0-t é mais sensível que Cmax para detectar diferenças. / Bioequivalence studies are designed to compare the in vivo performance of different formulations of the same drug or different drug products by a randomized crossover study. Pharmacokinetic parameters are obtained from the drug concentration-time profile in blood, serum, or plasma. The most frequently used pharmacokinetic parameters are area under the plasma or blood concentration-time curve (AUC), maximum concentration (Cmax) and time to achieve maximum concentration (tmax). Bioequivalence is concluded if the average bioavailability of the test formulation is within (80%, 125%) that of the reference formulation, with a certain assurance, that is, an equivalence criterion of 80% to 125% for assessment of bioequivalence based on the ratio of average bioavailability is employed. The logarithmic transformation is used for AUC and Cmax. Accuracy in measuring pharmacokinetics parameters directly affects accuracy of bioequivalence tests. Since the number of blood samples per patient is limited, sampling points should be chosen such that the time concentration profile is adequately defined so as to allow the calculation of relevant parameters. According to guidelines proposed by the National Agency of Sanitary Vigilance of Brazil (ANVISA), bioequivalence studies can be conducted only if the difference in drug content between the reference and test product is less than or equal to 5%. The goals of this study are to evaluate the influence of differences in amount of active moiety present in the formulation and possibility of reducing the number of sampling points in bioequivalence studies and to discuss the impact of these parameters in bioequivalence conclusions. For these approaches, simulations and an in vivo study were done. The drug selected was cefadroxil. Cefadroxil presents ideal pharmacokinetics and pharmacodynamics characteristics for this kind of study, such as high bioavailability, low intra and intersubject variability, short elimination rate and wide therapeutic range. Microsoft Office Excel 2003 software was used to simulate drug concentration-time profiles for different doses and several sampling schedules, and to determine 90% confidence interval. Simulations were done by two models: a) based on assumed maximum and minimum pharmacokinetic parameters values; b) based on assumed intra and intersubject variability. Ten different doses, ranging from -10% to 20% of the reference dose, and six sampling schedules were evaluated. The in vivo study was performed with four different cefadroxil doses. Their relative bioavailability were evaluated in 24 healthy volunteers who received a single oral dose of each preparation. An open, randomized clinical trial designed as four-periods and four sequences crossover with 7-days washout between doses was employed. Plasma samples for assessments of their cefadroxil concentration by HPLC-DAD were obtained over 8 h after administration. Pharmacokinetics parameters tmax, Cmax and AUC0-t were evaluated using different doses and sampling schedules. For the purpose of bioequivalence analysis Cmax and AUC0-t were considered. For each schedule, to claim bioequivalence in average bioavailability, a 90% confidence interval was constructed for ratio of average between test and reference products and compared with (80%, 125%) limits. If the constructed confidence interval falls within the limits, then the two formulations are considered bioequivalent. The results obtained by simulate time-concentration profiles, showed good correlation with real data. Comparing the results obtained through in vivo study and the two simulations models, the simulations based in intra and intersubject variability was more predictive. In conclusion, no significant differences were found between sampling schedules evaluated, since the sampling time around tmax were maintained in sampling schedules. Bioinequivalence was observed when the difference between cefadroxil doses was higher than 14%. The parameter AUC0-t was more sensitive than Cmax to detect differences.

Pour assurer les communications dans un réseau de capteurs sans fil, les capteurs utilisent un modèle simplifié de protocoles en couches inspiré du modèle OSI. Ce modèle comporte cinq couches, chaque couche devant assurer des fonctionnalités indépendantes et particulières. Nous nous intéressons à deux couches qui sont impliquées directement dans les décisions assurant les communications, la couche Liaison de données dans laquelle le protocole MAC assure la coordination des communications entre voisins directs, et la couche Réseau dans laquelle le protocole de routage est responsable de trouver une route entre un émetteur et un récepteur. Chacune des deux couches vise à améliorer certaines métriques, comme la latence, mais les décisions incohérentes venant de différents protocoles peuvent ne pas le permettre. Par conséquent, les décisions spatiales du protocole de routage et les décisions temporelles du protocole MAC doivent être corrélées pour optimiser la latence des communications. Les protocoles cross-layer résolvent ce problème soit en assurant des communications entre des protocoles des deux couches, soit en combinant les deux couches en une nouvelle couche. Dans ce contexte, cette thèse étudie les protocoles cross-layer existants entre MAC et routage et propose de nouvelles approches ayant comme but de minimiser la latence des communications. Dans un premier temps, nous avons proposé un protocole de routage qui utilise des informations du protocole MAC qu’est un TDMA pour trouver un chemin entre le noeud qui capte les données et la station de base tout en minimisant la latence des communications [1]. Ensuite, nous nous sommes intéressés au cas inverse, i.e. des approches MAC qui utilisent des informations de routage pour établir des ordonnancements TDMA de communication pour les nœuds du réseau, ces ordonnancements visant toujours à optimiser la latence des communications [2, 3, 5].Enfin, dans [4], nous avons proposé une approche qui combine un protocole MAC et un protocole de routage en un seul protocole. / Traditionally, in Wireless Sensor Networks, protocols are designed independently in the layered protocol stack, and metrics involved in several layers can be affected. Communication latency is one metric example, impacted by both the routing protocol in the network layer and the MAC protocol in the data link layer. Cross-layer protocols are known to be more efficient when exploiting the dependencies between these layers.In this context, and aiming to minimize the communication latency, we propose different cross-layer approaches concerning routing trees and TDMA schedules. First, we propose a routing approach using information of the TDMA schedule. Then, we propose different TDMA scheduling approaches which use information of the routing tree. Finally, we propose an approach that combines MAC and routing to produce a routing tree and a TDMA schedule simultaneously. Extensive simulations have shown better results of our contributions compared to the state of the art in terms of latency. Other metrics such as the energy consumption, the duty cycle of the nodes and the number of hops in the routing paths were also considered during the evaluation of our contributions.

Living in a time where mobility and wireless information are of great interest when developing new computer artifacts, but paper and pen, which are the most used artifacts of today for taking brief notes and scheduling, are easy not to consider even though we have seen that they are very mobile. In this report we are discussing the use of both paper and mobile computer artifacts and their properties to see where mobile computer artifacts can support or replace paper artifacts in connection to brief notes and schedules. We believe that the work toward a design is just as important as the design it self, which is why this report also includes the methods and the results from it. Our research question is how different designs affect the possibilities of taking notes, planning and also what paper artifacts mediate to you, which digital do not do today. The question resulted in ideas of how the properties of paper and digital artifacts should be considered in the developing of computer artifacts for taking brief notes and scheduling, design ideas and a mock-up of our Digital Interactive Organizer.

The purpose of this study was to examine the impact of school schedule on student achievement and attendance of ninth and tenth grade students in metropolitan area Texas high schools (n = 22) and campus dropout rates. High schools that were analyzed in this study made a transition from A/B block scheduling in the 2003-04 school year to a traditional school schedule in the 2004-05 school year. Academic achievement, attendance rates and dropout rates were gathered through the archived files of the Texas Agency through the Academic Indicator of Excellence System (AEIS). Academic achievement was measured by the Texas Assessment of Knowledge and Skills (TAKS) Reading/Language Arts and Mathematics standardized tests. This study compared the mean scores of ninth grader student achievement, attendance, and dropout rates from the 2003-04 school year to the mean scores of the tenth graders from the same schools from the 2004-05 school year, after the schools converted from an A/B block schedule to a traditional class schedule. Each independent variable was divided into four subgroups; campus mean results, minority student results, limited English proficient (LEP) student results, and low-socioeconomic student results. Students under the A/B block scored significantly higher in reading achievement than when they were instructed the following year under a traditional schedule. Paired sample t-tests were conducted to analyze the data for each subgroup, and showed there was a statistically significance in reading / language arts student achievement scores for all subgroups. Statistical significance was determined with a ninety five percent confidence level (p < 0.05). Statistical analysis revealed varied results in mean scores for math academic achievement and attendance rates, but no statistical significant difference. Comparison of data showed a slight increase in mean scores for dropout rates in traditional schedule, however the results were not significant.