Dissertations / Theses on the topic 'Extensional mixer'

Dans ce travail de thèse, des mélanges réactifs de polymères thermoplastiques immiscibles PMMA,PE et PS ont été réalisés dans un mélangeur (RMX®) qui génère principalement des écoulements élongationnels connus pour leurs pouvoirs distributifs et dispersifs même lorsque les composants ont une différence de viscosité importante. La polymérisation in-situ du styrène a été conduite par auto-polymérisation thermique et grâce à des amorceurs radicalaires. Différentes méthodes de préparations et paramètres de mélanges ont été testés puis évalués par l’analyse d’images de microscopie électronique. Les plus petits nodules de PS que nous avons obtenus ont un rayon moyen de l’ordre de 50 nm. Des mélanges binaires 90/10 à base de PS ou PE et d’un thermodur polyépoxyde (MDEA/DGEBA) ont également été réalisés. Les nodules sphériques les plus petits que nous avons obtenus ont un rayon moyen de l’ordre de 65 nm
In this work, binary and ternary reactive blends based on immiscible thermoplastic polymers PMMA,PE and PS were realized. The in-situ polymerization of the styrene, precursor of PS, was led by thermal self-polymerization or still thanks to radical initiator. Blends were realized in a mixer named RMX who generates mainly extensional flows known for their distributive and dispersive skill even if components have an important viscosity difference. Various methods of preparation and parameters of mixtures were tested. Morphology was evaluated by the analysis of electronic microscopy images.The average radiuses of the dispersed PS phase were compared with those observed in the literature. The smallest that we obtained have an average radius of 50 nm. Binary mixtures 90/10 %m with PS or PE and with a thermodur polyepoxide (MDEA/DGEBA) were also realized. The smallest spherical nodules that we obtained have an average radius of the order of 65 nm

Dans ce travail de thèse, des mélanges réactifs de polymères thermoplastiques immiscibles PMMA,PE et PS ont été réalisés dans un mélangeur (RMX®) qui génère principalement des écoulements élongationnels connus pour leurs pouvoirs distributifs et dispersifs même lorsque les composants ont une différence de viscosité importante. La polymérisation in-situ du styrène a été conduite par auto-polymérisation thermique et grâce à des amorceurs radicalaires. Différentes méthodes de préparations et paramètres de mélanges ont été testés puis évalués par l’analyse d’images de microscopie électronique. Les plus petits nodules de PS que nous avons obtenus ont un rayon moyen de l’ordre de 50 nm. Des mélanges binaires 90/10 à base de PS ou PE et d’un thermodur polyépoxyde (MDEA/DGEBA) ont également été réalisés. Les nodules sphériques les plus petits que nous avons obtenus ont un rayon moyen de l’ordre de 65 nm
In this work, binary and ternary reactive blends based on immiscible thermoplastic polymers PMMA,PE and PS were realized. The in-situ polymerization of the styrene, precursor of PS, was led by thermal self-polymerization or still thanks to radical initiator. Blends were realized in a mixer named RMX who generates mainly extensional flows known for their distributive and dispersive skill even if components have an important viscosity difference. Various methods of preparation and parameters of mixtures were tested. Morphology was evaluated by the analysis of electronic microscopy images.The average radiuses of the dispersed PS phase were compared with those observed in the literature. The smallest that we obtained have an average radius of 50 nm. Binary mixtures 90/10 %m with PS or PE and with a thermodur polyepoxide (MDEA/DGEBA) were also realized. The smallest spherical nodules that we obtained have an average radius of the order of 65 nm

This research effort is concerned with a class of mathematical programming problems referred to as Mixed-Integer Bilinear Programming Problems. This class of problems, which arises in production, location-allocation, and distribution-application contexts, may be considered as a discrete version of the well-known Bilinear Programming Problem in that one set of decision variables is restricted to be binary valued. The structure of this problem is studied, and special cases wherein it is readily solvable are identified. For the more general case, a new linearization technique is introduced and demonstrated to lead to a tighter linear programming relaxation than obtained through available linearization methods. Based on this linearization, a composite Lagrangian relaxation-implicit enumeration-cutting plane algorithm is developed. Extensive computational experience is provided to test the efficiency of various algorithmic strategies and the effects of problem data on the computational effort of the proposed algorithm. The solution strategy developed for the Mixed-Integer Bilinear Programming Problem may be applied, with suitable modifications,. to other classes of mathematical programming problems: in particular, to the Zero-One Quadratic Programming Problem. In what may be considered as an extension to the work performed on the Mixed-Integer Bilinear Programming Problem, a solution strategy based on an equivalent linear reformulation is developed for the Zero-One Quadratic Programming Problem. The strategy is essentially an implicit enumeration algorithm which employs Lagrangian relaxation, Benders' cutting planes, and local explorations. Computational experience for this problem class is provided to justify the worth of the proposed linear reformulation and algorithm.
Ph. D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1993.
On t.p., "[infinity]" appears as the mathematical sign, in subscript.
Includes bibliographical references (leaves 136-138).
by Edward D. Bielecki.
M.S.

Sorting out data into partitions is increasing becoming complex as the constituents of data is growing outward everyday. Mixed data comprises continuous, categorical, directional functional and other types of variables. Clustering mixed data is based on special dissimilarities of the variables. Some data types may influence the clustering solution. Assigning appropriate weight to the functional data may improve the performance of the clustering algorithm. In this paper we use the extension of the Gower coefficient with judciously chosen weight for the L2 to cluster mixed data.The benefits of weighting are demonstrated both in in applications to the Buoy data set as well simulation studies. Our studies show that clustering algorithms with application of proper weight give superior recovery level when a set of data with mixed continuous, categorical directional and functional attributes is clustered. We discuss open problems for future research in clustering mixed data.

Knowledge Discovery in Databases (KDD) is gaining importance with the rising amount of data being collected lately, despite this analytic software systems often provide only the basic and most used procedures and algorithms. The aim of this thesis is to extend RapidMiner, one of the most frequently used systems, with some new procedures for data preprocessing. To understand and develop the procedures, it is important to be acquainted with the KDD, with emphasis on the data preparation phase. It's also important to describe the analytical procedures themselves. To be able to develop an extention for Rapidminer, its needed to get acquainted with the process of creating the extention and the tools that are used. Finally, the resulting extension is introduced and tested.

A large-scale transition to renewable energy sources will become increasingly appealing as the issues of federal regulation, climate change, and decreased fossil fuel energy return on energy investment become more prevalent. Although renewable resources remain a small portion of the nation’s and Utah’s energy portfolio mix, current power purchase agreements indicate an impending boom. Cooperative Extension should play an integral role in the transition to renewable resources on the national, state, and local levels. The purpose of Extension is to provide objective, research-based, and credible information to improve local communities. There is a great opportunity for Extension agents to be trusted experts in educating and assisting farmers, ranchers, and homeowners in transitioning to renewable energy systems. This thesis identified the benefits, barriers, and opportunities for renewable energy outreach in Extension. Data were collected through a nationwide online survey and focus group interviews, in addition to a Utah-based online survey. The nationwide survey and interviews revealed a need and demand for increased renewable energy programming in Extension. This need became further evident after a nationwide inventory discovered that only twenty-two of fifty states have distinct renewable energy departments, programs, or discipline areas. A Utah-based needs assessment revealed that fifty-nine percent of Utah State University (USU) Extension employees agreed that there was a need for a statewide renewable energy specialist. Additionally, more than fifty-five percent of employees agreed that there was an internal and public demand for USU Extension to provide and receive renewable energy information, programs, education, and outreach. The Utah-based survey also revealed differing perceptions of the environmental harmfulness of common energy sources. Different attitudes toward conventional and renewable energy sources demonstrated the need for unbiased, properly messaged delivery of desired renewable energy programs.

Farm to School is a program that connects local and regional foods and other farm products to school meals, develops school gardens, and develops other types of Farm to School experiential learning programs for K-12 students. Since Farm to School began in the mid-1990\'s, Farm to School programs have been developed in all 50 states and Washington D.C. The National Farm to School Network has estimated that almost 12,500 schools are involved with Farm to School, and that during the 2011-2012 school year, 5.7 million students were reached through Farm to School programs and activities. Research to date investigating Farm to School has primarily focused on food system and school system stakeholders including school nutrition directors, food distributors, farmers, school teachers, students, and principals. Not as much research has explored Cooperative Extension\'s role in Farm to School. Farm to School programs are one method for Extension professionals to support community food system development while addressing pressing social concerns related to agricultural viability and public health. Drawing on reasoned action theory and social movement theory, the purpose of this study was to explore food system change through an analysis of Cooperative Extension\'s role in the Farm to School movement. In this two-phase explanatory sequential mixed methods research study, the behavioral intentions/behaviors of Cooperative Extension professionals were analyzed. Additionally, the goals, strategies, and knowledge production of Cooperative Extension professionals participating in the Farm to School movement were explored. Data were collected through an online survey distributed to Extension professionals in eight states. A total of 931 Extension professionals completed the questionnaire resulting in a 48 percent response rate. Data were also collected through a state-based case study that explored Ohio State University (OSU) Extension involvement and leadership in the Ohio Farm to School Program. The case study included 21 interviews with OSU Extension professionals and Farm to School program partners. Regression models were developed to explore which behavioral intentions are statistically significant in explaining Extension participation in the Farm to School movement. Results show that past participation in a Farm to School training program, knowledge about Farm to School, attitude towards Farm to School, perceived social norms towards Farm to School, and perceived behavioral control towards Farm to School are positively associated with participation in the Farm to School movement. Drawing on Stevenson, Ruhf, Lezberg, and Clancy (2007), qualitative analysis found that OSU Extension professional\'s goals for the Farm to School movement were primarily related to food system transformation and inclusion, and their strategies were primarily related to connection. Drawing on Eyerman and Jamison (1991), qualitative analysis also found that OSU Extension professionals were producing primarily organizational knowledge through participation in the Farm to School movement. Additionally, qualitative analysis found that Cooperative Extension Systems are home to several Farm to School movement intellectuals. This study concludes with a discussion of recommendations for Cooperative Extension participation in the Farm to School movement, recommendations for Farm to School program partners, and recommendations for future research in Farm to School.
Ph. D.

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CNPq
Os polímeros biodegradáveis apresentam-se como uma alternativa ambientalmente correta para a sociedade, uma vez que minimizam problemas ambientais e reduzem acúmulo de resíduos plásticos. O presente trabalho investiga a degradação e a extensão de cadeia do polímero biodegradável, poli(butileno adipato tereftalato) (PBAT) com um aditivo extensor de cadeia epoxídico (Joncryl). O PBAT sem aditivar e aditivado com diferentes concentrações de extensor de cadeia foi processado em um misturador interno de laboratório Haake Rheomix 3000 com rotores tipo “roller”. A variação da massa molar foi estimada a partir de dados de temperatura e torque versus tempo fornecidos pelo equipamento durante o processamento do fundido. O efeito do aditivo depende fortemente da temperatura de processamento. A aditivação durante o processamento do fundido nos níveis testados, não somente compensou a discreta degradação da resina durante o processamento no misturador interno como resultou no aumento líquido da massa molar: a massa molar mais que duplicou a 230°C com 2% de aditivo. Para elevadas concentrações de aditivo observaram longos tempos de indução com queda catastrófica do torque, atribuíveis à mistura imperfeita dos componentes.
Biodegradable polymers are an environmentally friendly alternative, as they minimize environmental problems and reduce accumulation of waste plastics. This work is concerned with degradation and chain extension of the biodegradable polymer poly(butylene-adipate-terephthalate) (PBAT) with an epoxidic chain extender additive (Joncryl). The PBAT without and with different concentrations chain extender was processed in a laboratory internal mixer Haake Rheomix 3000 with "roller" type rotors. The variation of molar mass was estimated from temperature and torque data versus time provided by the equipment during melt processing. The effect of the additive depends mostly on processing temperature, less on additive concentration. Incorporation of additive during melt processing not only offset the slight degradation of the resin during processing in the internal mixer, but resulted in net increase of molecular weight. The molecular weight more than doubled at 230°C with 2% additive. For high additive concentrations were observed sometimes long times of induction with catastrophic fall of torque, attributable to imperfect mixing of the components

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CNPq
Este estudo visa avaliar a influência de um oligômero multifuncional de estirenoacrílico (POLYAD PR 002), comercializado como extensor de cadeia para polímeros de condensação, no aumento da massa molar do poli (tereftalato de etileno) (PET) e, consequentemente, na restituição de suas propriedades reológicas. O comportamento foi analisado em PET pós-consumo (PETPC) oriundo de garrafas incolores do estado da Paraíba, bem como no PET virgem (PETV) para um parâmetro comparativo. Os polímeros foram processados sem e com a incorporação do aditivo extensor de cadeia em diferentes níveis, para possibilitar o desenvolvimento de diferentes grades de PET. Foi utilizado um misturador interno acoplado ao reômetro de torque Haake Rheomix 3000QC da PolyLab QC, com rotores do tipo roller operando a 265ºC e 60 rpm. Na primeira etapa, o processamento foi realizado em um tempo de 16 min, empregando diferentes concentrações do aditivo (1,5%, 3% e 5% em massa), e na segunda etapa os polímeros sem e com a incorporação do aditivo extensor, nas concentrações 1,5 e 3% em massa, foram processados e reprocessados em um tempo de 30 min. As amostras obtidas foram caracterizadas por reometria de torque. A partir de medições de torque e temperatura obtidas pelo equipamento foi possível realizar uma avaliação das massas molares. De acordo com os resultados, confirma-se que as estimativas com base em medições de torque em tempo real são indicadores rápidos e precisos da eficácia da extensão da cadeia no PET e que a incorporação do aditivo ao PETV e ao PETPC teve uma forte influência no aumento da sua massa molar.
This study is concerned with the effect of a styrene-acrylic multifunctional oligomer (POLYAD PR 002), marketed as a chain extender for condensation polymers, in the increase of molecular weight of poly (ethylene terephthalate) (PET) and, consequently, the restitution of their rheological properties. This behavior was analyzed in post-consumer PET (PETPC) from colorless bottles collected in the State of Paraíba, as well as in virgin PET (PETV) for comparison. The polymers were processed with and without the incorporation of the chain extender additive at different levels to facilitate developing different grades of PET. An internal mixer coupled to the torque rheometer Haake Rheomix 3000QC of PolyLab QC, with roller type rotors operating at 265ºC and 60 rpm was used. In the first stage, processing was performed during 16 min, with different additive concentrations (1.5%, 3% and 5% by weight) and in a second stage, polymers with and without the incorporation of additive concentrations 1.5 and 3% by weight were processed and reprocessed during 30 min. The samples were characterized by torque rheometry. From torque and temperature measurements was possible to evaluate molar masses. According to the results, it is evident that estimates based on realtime torque measurement are fast and accurate indicators of the effectiveness of chain extension, and that the incorporation of the additive to PETV and PETPC had a strong effect in increase its molar mass

Doutoramento em Nanociências e Nanotecnologia
Solid oxide fuel (SOFCs) and electrolyzer (SOECs) cells have been promoted as promising technologies for the stabilization of fuel supply and usage in future green energy systems. SOFCs are devices that produce electricity by the oxidation of hydrogen or hydrocarbon fuels with high efficiency. Conversely, SOECs can offer the reverse reaction, where synthetic fuels can be generated by the input of renewable electricity. Due to this similar but inverse nature of SOFCs and SOECs, these devices have traditionally been constructed from comparable materials. Nonetheless, several limitations have hindered the entry of SOFCs and SOECs into the marketplace. One of the most debilitating is associated with chemical interreactions between cell components that can lead to poor longevities at high working temperatures and/or depleted electrochemcial performance. Normally such interreactions are countered by the introduction of thin, purely ionic conducting, buffer layers between the electrode and electrolyte interface. The objective of this thesis is to assess if possible improvements in electrode kinetics can also be obtained by modifying the transport properties of these buffer layers by the introduction of multivalent cations. The introduction of minor electronic conductivity in the surface of the electrolyte material has previously been shown to radically enhance the electrochemically active area for oxygen exchange, reducing polarization resistance losses. Hence, the current thesis aims to extend this knowledge to tailor a bi-functional buffer layer that can prevent chemical interreaction while also enhancing electrode kinetics.The thesis selects a typical scenario of an yttria stabilized zirconia electrolyte combined with a lanthanide containing oxygen electrode. Gadolinium, terbium and praseodymium doped cerium oxide materials have been investigated as potential buffer layers. The mixed ionic electronic conducting (MIEC) properties of the doped-cerium materials have been analyzed and collated. A detailed analysis is further presented of the impact of the buffer layers on the kinetics of the oxygen electrode in SOFC and SOEC devices. Special focus is made to assess for potential links between the transport properties of the buffer layer and subsequent electrode performance. The work also evaluates the electrochemical performance of different K2NiF4 structure cathodes deposited onto a peak performing Pr doped-cerium buffer layer, the influence of buffer layer thickness and the Pr content of the ceria buffer layer. It is shown that dramatic increases in electrode performance can be obtained by the introduction of MIEC buffer layers, where the best performances are shown to be offered by buffer layers of highest ambipolar conductivity. These buffer layers are also shown to continue to offer the bifunctional role to protect from unwanted chemical interactions at the electrode/electrolyte interface.
As pilhas de combustível e eletrolisadores de óxido sólido (PCOSs e EOSs) têm sido promovidas a tecnologias promissoras para estabelecer o abastecimento de combustível e sua utilização futura em sistemas de energia limpa. As PCOSs são dispositivos que produzem energia elétrica pela oxidação de combustíveis como o hidrogénio ou de hidrocarbonetos de elevada eficiência. Alternativamente, as EOSs funcionam de maneira inversa, na qual podem ser gerados combustíveis sintéticos ao fornecer energia eléctrica renovável ao sistema. É, pois, devido a esta natureza semelhante e ainda que inversa, que estes dispositivos têm sido tradicionalmente construídos a partir de materiais compatíveis. No entanto, a entrada no mercado destas tecnologias encontra-se ainda condicionada por diversos factores. Um dos mais limitantes, está associado a problemas de estabilidade química entre os constituintes da célula, que podem reduzir a longevidade a elevadas temperaturas de operação e/ou a um desempenho eletroquímico insuficiente. Normalmente, tais problemas de compatibilidade são minimizados pela introdução de uma camada de proteção muito fina constituída por um material condutor puramente iónico, na interface elétrodo/eletrólito. Deste modo, o objetivo deste trabalho é avaliar se modificando as propriedades de transporte destas camadas de proteção se pode conduzir ao aumento das propriedades de cinética do elétrodo, através da introdução de catiões polivalentes. A introdução de condutividade eletrónica menor na superfície do electrólito foi anteriormente relatada apresentando uma melhoria muito considerável das zonas eletroquimicamente activas para a permuta de oxigénio, reduzindo, desta forma, as perdas de resistência de polarização.Assim, esta dissertação tem por objetivo desenvolver este conhecimento para adaptar uma camada de proteção bifuncional que consiga evitar os problemas de interação química e ao mesmo tempo aumentar a cinética dos elétrodos. Esta dissertação apresenta um cenário típico de um eletrólito à base de zircónia estabilizada com ítrio combinado com um elétrodo de oxigénio contendo lantanídeos. Foram investigados como materiais de proteção, os sistemas de céria dopada com gadolínio, térbio e praseodímio. As propriedades inerentes à condução eletrónica e iónica mista (MIEC) dos materiais dopados foram analisadas e agrupadas. Posteriormente, foi realizada uma análise detalhada sobre o impacto das camadas de proteção na cinética do elétrodo de oxigénio em dispositivos PCOS e EOS. Foi dada especial atenção às potenciais relações entre as propriedades de transporte da camada proteção e subsequente desempenho do elétrodo. O trabalho também avalia o desempenho eletroquímico de cátodos de K2NiF4 com diferentes estruturas, depositadas sobre a camada de proteção que apresentou melhor desempenho, isto é, a céria dopada com praseodímio, assim como a influência da espessura da camada e da fração de Pr presente na céria. Demonstrou-se que a introdução de camadas de proteção à base de MIECs levou a um aumento drástico no desempenho do elétrodo, nomeadamente pelos MIECs de maior condutividade ambipolar. Estas camadas de proteção utlizadas provaram ser também eficazes em manter o papel de inibidores de interactividade química na interface elétrodo/eletrólito.

A translational gap exists between the development of an evidence-based health promotion intervention and its eventual implementation in the intended setting. This lack of translation impacts the uptake of health promotion interventions within delivery systems such as the Cooperative Extension Service (Extension). Within this system, Extension educators serve as the intermediaries addressing needs in the communities in which they are employed with support from Extension health specialists. Previous research has shown that educators utilize other peer educators and specialists to learn and adopt health promotion programming, but these studies are over two decades old (e.g., missing technological advances such as Internet and social media) and often focused on a single state Extension system. The purpose of this research was to understand how evidence-based health promotion intervention information is shared within Cooperative Extension by 1) identifying information sources and channels of Extension specialists and educators while 2) identifying the characteristics of an intervention that aid in the adoption and uptake of these health promotion interventions. The first mixed-methods study aimed to identify information sources and channels used by Extension educators from a national sample and learn their preferences for information delivery. Results of this study (Manuscript 1), identified specialists as the key information source Therefore, the second study (Manuscript 2) focused on Extension health specialists' preferences for information sources and channels while also 1) determine how specialists communicate with educators 2) preliminary thoughts on a dissemination intervention. The final study (Manuscript 3) explored the intervention characteristics that are both educator and specialists deemed most important to their adoption decision-making process. The results of this dissertation inform the development of a dissemination intervention to bridge the translational gap across Extension. The information sources and channels used and trusted by both Extension educators and specialists are highlighted in this work. Additionally, specialists have given insight for consideration for an online repository that can be used on demand to both facilitate the adoption and uptake of health promotion interventions as needed by Extension Educators.
Doctor of Philosophy

The aim of this thesis is project documentation of the revitalization of a farming estate for living purposes. The complex includes four buildings in the city of Vitín in Southern Bohemia. Originally built in the 17th century, this estate falls under the care of historical monuments. This thesis deals with rehabilitation of wet masonry and reconstructing three buildings of the estate. The original perimeter walls are mixed, a gabled roof. Building A and C are two floored, building B is one floor. Presently only building C is used for living, the others serve as storage. Part of the reconstruction includes an extension wind lobby, indoor parking for a personal automobile, and a conservatory. The new structures are designed from aerated concrete Ytong blocks, Liapor and sprayed insulation made of polyurethane foam.

La proposition d'un modèle de développement qui concilie la conservation de l'environnement, en particulier des ressources forestières, et le développement socio-économique reste un défi à relever globalement, en particulier dans la région amazonienne. En raison de son ampleur, une attention particulière est portée à la portion brésilienne de l'Amazonie et plus précisément à ses différentes formes d’agriculture en raison de leur importance socio-économique et de leur potentiel d'altération des écosystèmes et des services écosystémiques (SE). Dans ce contexte, l’agriculture familiale apparaît incontournable pour promouvoir le développement rural durable. Malgré son importance, les acteurs locaux qui soutiennent les exploitations agricoles familiales sont confrontés à de nombreux défis pour promouvoir la transition agroécologique. La question générale de cette thèse est : Comment le cadre conceptuel des SE peut-il servir de base cognitive et opérationnelle pour soutenir la transition agroécologique ? Nous examinons deux municipalités contrastées situées dans la partie orientale de l'Amazonie brésilienne : Irituia, dont le secteur agricole est dominé par une agriculture familiale qui se tourne vers la biodiversification ; et Paragominas, qui présente une prédominance de l'agriculture industrielle à grande échelle, qui coexiste avec l'agriculture familiale. Nous avons adopté une perspective multi-acteurs, impliquant une diversité d'acteurs locaux (e.g., des décideurs politiques, des chercheurs, des agents de vulgarisation rurale, des agriculteurs). Nous avons implémenté une « approche de méthodes mixtes » combinant des méthodologies qualitatives, telles que des entretiens semi-directifs et l'observation participante, avec des méthodologies semi-quantitatives telles que des questionnaires et un jeu de rôles. Nous avons d'abord cherché à comprendre la perception qu'ont les acteurs locaux sur la coproduction des SE. Une diversité de SE est perçue par ces acteurs locaux. La perception des SE et de leur processus de coproduction diffère sensiblement selon le type d'activité exercée par les acteurs et leur municipalité. Nous montrons également comment la nature de leurs connaissances (plus scientifique ou empirique) joue sur leur manière de percevoir les SE. Nous avons par ailleurs cherché à comprendre l'importance de ces perceptions dans le processus de prise de décision sur l'utilisation des terres en étudiant l’influence sur ce processus de décision de certains facteurs contextuels externes à l’agroécosystème (notamment les marchés institutionnels) et internes (e.g., la main-d'œuvre, les coûts, les aspects cognitifs). Nous avons constaté que la réussite de la valorisation de l'agrobiodiversité au moyen de marchés institutionnels dépend de la manière dont ils sont administrés au niveau municipal. Des facteurs internes à l'exploitation, tels que le travail, les revenus, les valeurs, influencent également ce processus de prise de décision. Finalement, nous avons cherché à comprendre comment les connaissances générées lors des étapes précédentes pouvaient contribuer à rendre opérationnelle la transition agroécologique dans les sites d’étude. Ces connaissances ont contribué à révéler les attentes et les facteurs qui motivent les actions des acteurs locaux relatives à la gestion de l'utilisation des terres. Elles ont été obtenues par et utilisées pour alimenter des outils méthodologiques visant à soutenir la transition agroécologique. Au final, nous avançons que le cadre conceptuel de la coproduction des SE permet d’aller au-delà de l'exploration des éléments corrélés à la gestion des agroécosystèmes. Il constitue également un outil pertinent pour stimuler la communication sur le sujet entre les différents acteurs. La compréhension des mécanismes qui soutiennent la coproduction des SE et le partage des différentes connaissances et perceptions associées éveillent une prise de conscience collective en faveur de la transition agro-écologique
The proposal of a model of development that reconciles environmental conservation, especially of forest resources, and socioeconomic development is still a challenge to be achieved worldwide, especially in the Amazon region. Due to its amplitude, the Brazilian portion of the Amazon is a matter of great concern nationally and internationally. Agriculture stands out in the Brazilian Amazon for its socioeconomic importance and its tremendous potential to alter ecosystems and the provision of ecosystem services (ES). Among the different forms of agriculture (i.e. large and small farmers), family farms are key players for promoting rural sustainable development. Despite its importance, local actors supporting family farms face numerous challenges to promote agroecological transition of these farms. The general question that we want to contribute to with this thesis is: How can the conceptual framework of ES serve as a cognitive and operational basis to support the agroecological transition? We carried out this research in two contrasting municipalities in the eastern part of the Brazilian Amazon, Irituia and Paragominas. The farming sector of the first study site is dominated by family farming, which is often biodiversified. Contrastingly, large-scale industrial agriculture predominates in the second study site, although it coexists with family farming. We adopted a multi-actor perspective, with the participation of a heterogeneous set of local actors (e.g. policy makers, researchers, rural extension agents, farmers) related to rural issues. We implemented a “mixed methods approach” combining well-tested qualitative methodologies, such as semi-directive interviews and participant observation, with semi-quantitative methodologies such as questionnaires and a role-playing game. We first aimed to understand the perception of different local actors about ES and their co-production process. We observed that, in general, a diversity of ES is perceived by local actors. The perception of ES and the different possible ways to co-produce these ES differ significantly among actors. The type of activity performed by the stakeholders and their municipality are the main factors influencing their perception of ES co-production. The type of knowledge (more scientific or empirical) was also relevant to distinguish between the ways to perceive ES. We also sought to understand the importance of these perceptions in the decision-making process on land use. We investigated some contextual factors that influence this decision making process, focusing on factors external (notably institutional markets) and internal (e.g. labor, costs, cognitive aspects) to the agroecosystem. We realized that these markets are important for valuing agrobiodiversity, but this will depend on how they are managed at a municipal level and on the local institutional landscape. Accordingly, the agroecosystem may evolve towards agroecological or non-agroecological standards. Internal factors in the farm, such as labor, money, values also influence this decision making process. Finally, we sought to understand how the knowledge generated previously could contribute to operationalize the agroecological transition in our two study sites. Knowledge about ES issues generated in our research site contributed to disclose the expectations and factors that drive the actions of stakeholders regarding land use management. This knowledge was obtained through and was used to feed methodological tools to support agroecological transition. Finally, we highlight that the conceptual framework of ES co-production not only enables exploring elements correlated to agroecosystem management, it also serves as a viable tool to stimulate the communication of different actors on the subject. A better understanding of the mechanisms underlying the co-production of ES and the sharing of different knowledge and perceptions can support more collective awareness toward agroecological transition

De nombreuses études cliniques ou interventions de lutte ont été faites ou sont en cours en Afrique pour la lutte contre le fléau du paludisme. En zone d'endémie, le paludisme est une maladie récurrente. La revue de littérature indique une application limitée des outils statistiques appropriés existants pour l'analyse des données récurrentes de paludisme. Nous avons mis en oeuvre des méthodes statistiques appropriées pour l'analyse des données répétées d'essais thérapeutiques de paludisme. Nous avons également étudié les mesures répétées d'hémoglobine lors du suivi de traitements antipaludiques en vue d'évaluer la tolérance ou sécurité des médicaments en regroupant les données de 13 essais cliniques.Pour l'analyse du nombre d'épisodes de paludisme, la régression binomiale négative a été mise en oeuvre. Pour modéliser la récurrence des épisodes de paludisme, quatre modèles ont été utilisés : i) Les équations d'estimation généralisées (GEE) utilisant la distribution de Poisson; et trois modèles qui sont une extension du modèle Cox: ii) le modèle de processus de comptage d'Andersen-Gill (AG-CP), iii) le modèle de processus de comptage de Prentice-Williams-Peterson (PWP-CP); et iv) le modèle de Fragilité partagée de distribution gamma. Pour l'analyse de sécurité, c'est-à-dire l'évaluation de l'impact de traitements antipaludiques sur le taux d'hémoglobine ou la survenue de l'anémie, les modèles linéaires et latents généralisés mixtes (« GLLAMM : generalized linear and latent mixed models ») ont été mis en oeuvre. Les perspectives sont l'élaboration de guides de bonnes pratiques de préparation et d'analyse ainsi que la création d'un entrepôt des données de paludisme
Numerous clinical studies or control interventions were done or are ongoing in Africa for malaria control. For an efficient control of this disease, the strategies should be closer to the reality of the field and the data should be analyzed appropriately. In endemic areas, malaria is a recurrent disease. Repeated malaria episodes are common in African. However, the literature review indicates a limited application of appropriate statistical tools for the analysis of recurrent malaria data. We implemented appropriate statistical methods for the analysis of these data We have also studied the repeated measurements of hemoglobin during malaria treatments follow-up in order to assess the safety of the study drugs by pooling data from 13 clinical trials.For the analysis of the number of malaria episodes, the negative binomial regression has been implemented. To model the recurrence of malaria episodes, four models were used: i) the generalized estimating equations (GEE) using the Poisson distribution; and three models that are an extension of the Cox model: ii) Andersen-Gill counting process (AG-CP), iii) Prentice-Williams-Peterson counting process (PWP-CP); and (iv) the shared gamma frailty model. For the safety analysis, i.e. the assessment of the impact of malaria treatment on hemoglobin levels or the onset of anemia, the generalized linear and latent mixed models (GLLAMM) has been implemented. We have shown how to properly apply the existing statistical tools in the analysis of these data. The prospects of this work remain in the development of guides on good practices on the methodology of the preparation and analysis and storage network for malaria data

Les cellules sont entourées de membranes lipidiques organisées en bicouche séparant ainsi le milieu intracellulaire du milieu extérieur. L’une des caractéristiques des cellules eucaryotes est de posséder une distribution asymétrique des lipides constituants les membranes de la voie sécrétoire. En effet, dans ces membranes, la phosphatidylcholine (PC) et les sphingolipides (SL) sont majoritairement retrouvés sur le feuillet externe alors que la phosphatidylsérine (PS) et la phosphatidyléthanolamine (PE) sont séquestrées sur le feuillet interne. Cette asymétrie est maintenue grâce à la présence de transporteurs de lipides. Parmi ces transporteurs, on retrouve les flippases, qui grâce à l’énergie apportée par la consommation d’ATP, transportent les lipides du feuillet interne vers le feuillet externe. Les flippases appartiennent à la superfamille des ATPases de type P et ont été reliées à différentes pathologies humaines lorsqu’elles sont mutées. Par exemple, des mutations du gène ATP8B1 sont responsables d’une forme de cholestase intrahépatique, une maladie hépatique sévère. Dans cette thèse, nous avons étudier le mécanisme de régulation de deux flippases : la flippase de levure PS spécifique Drs2p/Cdc50p ainsi que la flippase humaine ATP8B1/CDC50A. Les deux flippases ont été exprimées dans la levure de bière S. cerevisiae et purifiées afin de réaliser leur caractérisation fonctionnelle. Nos résultats montrent que les deux flippases sont régulées par des phosphoinositides et auto-inhibées par leurs extrémités N- et C-terminales
Living cells are surrounded by membranes organized in bilayers, separating the intracellular medium from the extracellular environment. A hallmark of eukaryotic membranes from the late secretory/endocytic pathways is the asymmetric distribution of phospholipids between the two leaflets. Indeed, phosphatidylcholine (PC) and sphingolipids (SL) are mainly found in the outer leaflet whereas phosphatidylserine (PS) and phosphatidylethanolamine (PE) are sequestered in the inner leaflet. This asymmetry is maintained thanks to different membrane lipid transporters. Among them, flippases, which are transporters fueled by ATP hydrolysis, translocate lipids from the outer to the inner leaflet. Flippases belong to the P4-ATPase family and have been linked to several diseases. For instance, mutated forms of a human P4-ATPase, ATP8B1, are responsible for intrahepatic cholestasis, a severe liver disease. In this thesis, we investigated the regulatory mechanism of two flippases, the yeast PS-specific flippase complex Drs2p/Cdc50p, and the human disease-related flippase complex ATP8B1/CDC50A. Both proteins were expressed in S. cerevisiae and purified for downstream functional characterization. Our results demonstrate that both flippases are tightly regulated by phosphoinositides and autoinhibited by their N- and C-terminal extensions

Understanding tuberculosis transmission is vital for efforts at interrupting the spread of disease. Household contact studies that follow persons sharing a household with a TB case—so-called household contacts—and test for latent TB infection by tuberculin skin test conversion give investigators vital information about risk factors for TB transmission. In these studies, investigators often assume secondary cases are infected by the primary TB case, despite substantial evidence that infection from a source outside the home is often equally likely, especially in high-prevalence settings. Investigators may discard information on contacts who test positive at study initiation due to uncertainty of the infection source, or assume infected contacts were infected from the index case prior to study initiation. With either assumption, information on transmission dynamics is lost or incomplete, and estimates of household risk factors for transmission will be biased. This dissertation describes an approach to modeling TB transmission that accounts for community-acquired transmission in the estimation of transmission risk factors from household contact study data. The proposed model generates population-specific estimates of the probability a contact of an infectious case will be infected from a source outside the home—a vital statistic for planning effective interventions to halt disease spread—in additional to estimates of household transmission predictors. We first describe the model analytically, and then apply it to synthetic datasets under different risk scenarios. We then fit the model to data taken from three household contact studies in different locations: Brazil, India, and Uganda. Infection predictors such as contact sleeping proximity to the index case and index case disease severity are underestimated in standard models compared to the proposed method, and non-household TB infection risk increases with age stratum, reflecting longer at-risk duration for community-based exposure for older contacts. This analysis will aid public health planners in understanding how best to interrupt TB spread in disparate populations by characterizing where transmission risk is greatest and which risk factors influence household-acquired transmission. Finally, we present an open-source software package in the R environment titled upmfit for modular implementation of the Bayesian Markov Chain Monte Carlo methods used to estimate the model.
2018-05-10T00:00:00Z

碩士
國立中央大學
化學工程與材料工程學系
107
In recent years, carbon dioxide is one of the main greenhouse gases which lead to serious damage to our environment. Therefore, how to capture CO2 has become a global issue. A new type of material, mixed matrixed membranes (MMMs), which is composed of metal-organic framework (MOF) as filler embedded in a polymeric matrix and it can combine the advantages of both components. In this study, Matrimid® 5218 is used as polymeric matrix becaused of its high glass transition temperature, and NH2-MIL-53 is used as filler because of its significant breathing behavior. In this work, molecular dynamics (MD) and density functional theory (DFT) are applied to construct the pure Matrimid models and MMMs models, and NH2-MIL-53 models, respectively. Additionally, Monte Carlo (MC) simulations and mean square displacement (MSD) are used to analysis the gas transport mechanism. The pure Matrimid models are divided into three different systems for discussion, which are long, medium, and short chain system. Each system would adopt two different MD procedures to construct the models, which are NPT-NVT loop procedure and 31 MD step procedure. The results show that the long chain system fully exhibits the characteristics of polymer torsion, and as the chain length decrease, this characteristic will gradually disappear, resulting in decrease of free volume, further decreasing the gases adsorption ability. For gases diffusion, due to the gradual reduction of the free volume, the collision between the gases and polymer chain increase, resulting in an increase in gases diffusion. Furthermore, we found that the pure membrane adopting 31 MD step procedure are more reasonable and more in line with the experimental value, and is a more efficient MD method in this study. The narrow pore (NP) and large pore (LP) types of NH2-MIL-53 models are constructed. The results sohw that the amount of gases that can be adsorbed by the LP is higher than that of NP, and the most important influencing factor is the breathing behavior caused by the change of the pore size. Besides, the cluster models of NH2-MIL-53 adoping two different kinds of charge assignment are constructed as the filler to embedded into polymeric matrix. The MMMs models are constructed within different weight loading of NH2-MIL-53. The results show that the gas molecules cannot effectively adsorb in the pores of the clusters, so the gas adsorption performance is not as expected. We speculate that the charge distribution of the clusters makes it cannot retain the original characteristics of NH2-MIL-53. However, we have tried to use the original charge distribution from NH2-MIL-53 to apply on the cluster models. The results show that although the cluster model cannot maintain the electrical neutrality, it can enhance the sorption ability inside the MMMs. Despite the results in this study are not in agreement with the experiment, we can still observe certain trends and systematically discuss the mechanism of film adsorption on gases.

Abstract Crossdocking is a logistic strategy used to improve the effectiveness of goods distribution by aiming to decrease inventory and transportation costs. A distribution network is an integrated set of suppliers, distribution platforms and customers where strategic, tactical and operating decisions related to a single player could produce effects on some (or many) others. The state of the art on crossdocking logistic strategy highlights a mismatch between the description of a crossdocking platform and its mathematical formulation. Unloading, loading, sorting, consolidating, storing, labelling and handling are the activities performed within a crossdocking platform which are not included in the modelling part. Generally the authors include just the storing activity. These activities could be relevant for some problems such as scheduling, layout and distribution whereas they could be considered irrelevant for some other problems which do not reach the detail level on the internal functioning of the platform such as the location problems. Among these problems, the PhD dissertation deals with the distribution flow problem which consists in determining how to send products from suppliers to customers through crossdocking platforms. The activities performed at the platforms are associated to costs and capacity constraints for the available resources. For this reason a crossdocking platform cannot be represented by a single transshipment node. In order to take into account these features, the crossdocking platform is modelled with a transshipment nodes network: a receiving node which stands for the activities performed on the incoming products, a storing node, which stands for the inventory activity and a shipping node standing for the activities performed on the outgoing products. The literature review on distribution flow problems for the crossdocking strategy underlines another mismatch: the lack of a specific constraint for the transportation efficiency. A model is proposed to fill these gaps. The main idea is that the crossdocking, with appropriate differences, can be formulated as a Fixed Charge Network Flow Problem, well-known NP-hard problem. Two exact approaches, a Branch and Bound and a Branch and Cut algorithm, have been developed in order to solve the problem. These two procedures are customized on the network features and they are different from the default procedures embedded within the most diffused optimization software: Xpress and Cplex. Some pseudo-random instances have been generated with the aim to test the developed model and procedures. For the large instances, the obtained results have been compared with those obtained by the optimization software. The obtained results demonstrate the effectiveness of the developed procedures as well as of the crossdocking strategy in terms of average level of inventory. The second part of this PhD thesis deals with an application: the case of the distribution process through container terminal. A new model is proposed, extension of the previous one, which allows to take into account the specific features associated a container terminal. Once again, the model is formulated, with appropriate differences, as a Fixed Charge Network Flow Problem. In this case the model is validated with a real instance extracted by the current functioning of the container terminal of Naples (Italy), which represents the case study. Like the previous model, the obtained results validate the crossdocking strategy for the management of the terminal yard. This strategy, in fact, allows to drastically cut the average inventory time.