Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Total Body Irradiation is a special technique of radiotherapy used for conditioning for bone marrow transplantation. Its function is to immunosuppression, bone marrow ablation and destruction of malignant cells. How it is the irradiation of a large and irregular field is necessary to seek ways to offset the tissues so that the absorbed dose to the patient's body has a uniformity of ± 10%. In addition, other factors intervene so that this condition is satisfied, such as the choice of radiation source, the posture of the patient, the incidence geometry, the distance of treatment, the combination of fields, among others. To analyze how these factors influence the dose distribution in the body, in this study we were simulated computationally scenarios of Total Body Irradiation, using telecobaltherapy units and linear accelerator of 6 MV, for an estimated equivalent and effective doses using the code MCNPX of radiation transport and hybrid anthropomorphic simulators UFHADF and UFHADM in sitting postures to RLAT and LLAT irradiation, and lying to the AP and PA projections. To validate the spectra used in the simulations was calculated PDP for comparison with experimental measurements. As for the validation of TBI scenarios were estimated entrance dose rates in skin also for comparison with experimental measurements. The PDP curves are shown according to the literature. The values of the estimated dose rates are less than 10% relative difference in relation to the experimental measurements, which allowed us to estimate the dose in the organs. The simulation results show that the lateral irradiations of UF simulators in the sitting posture offer a less uniform dose distribution compared to radiation AP / PA with the simulator in lying posture. For the PA irradiation geometry the absorbed dose in the red marrow is approximately 20% higher than in the AP projection, which suggests that the first case is most appropriate for the destruction of diseased marrow. Regarding the use of attenuators objects for radiation attenuation in the lung there was a reduction of 23% of the absorbed dose by this organ, which shows their effectiveness and importance to these procedures. It was also observed that the decrease in patient treatment away from the radiation source and the room walls leads to a near increase of 10% and 5%, respectively, the absorbed dose, which suggests that treatments be more suitable carried out great distances focus-surface and far from the room's walls. The energy beam used for Total Body Irradiation, the most significant differences between the Cobalt-60 and linear accelerator 6 MV spectra were up to 46.23%, which occurred for the AP irradiation geometry, where observed that the first deposits most of its energy near the surface, which shows that more energy beams for irradiation are more effective at greater depths. Another factor analyzed was the combination of adjacent and overlapping fields for the treatment, leading to overdoses in some organs and committed dose uniformity as observed by other authors. The calculation of the effective dose showed that there is a greater overall commitment of the body to radiation in LLAT incidence geometry. It was also found that the effective dose is higher in the AP projection than PA as found in the literature. The analyzes show the importance and suggest a more detailed study of the exposure conditions for planning treatments for TB / A Irradiação de Corpo Inteiro é uma técnica especial de radioterapia utilizada para o condicionamento de transplante de medula óssea. Sua função é de imunossupressão, ablação da medula e destruição de células malignas. Por se tratar da irradiação de um campo grande e irregular é necessário buscar meios para compensação dos tecidos para que a dose absorvida pelo corpo do paciente tenha uma uniformidade de ±10%. Além disso, outros fatores interferem para que essa condição seja satisfeita, tais como a escolha fonte de radiação, a postura do paciente, a geometria de incidência, a distância de tratamento, a combinação de campos, entre outros. Para analisar a maneira como esse fatores influenciam na distribuição da dose no corpo, neste trabalho foram simulados computacionalmente cenários de Irradiação de Corpo Inteiro, que utilizam unidades de telecobaltoterapia e aceleradores lineares de 6 MV, para a estimativa da doses equivalente e efetiva utilizando o código de transporte de radiação MCNPX e os simuladores antropomórficos híbridos UFHADF e UFHADM nas posturas sentada, para irradiações RLAT e LLAT, e deitada para as projeções AP e PA. Para a validação dos espectros utilizados nas simulações foi calculada a PDP para a comparação com medidas experimentais. Já para a validação dos cenários de TBI foram estimadas as taxas de dose de entrada na pele também para a comparação com medidas experimentais. As curvas de PDP se mostraram de acordo com a literatura. Os valores das taxas de dose estimadas apresentaram uma diferença relativa menor que 10% em relação às medidas experimentais, o que permitiu estimar a dose nos órgãos. Os resultados das simulações mostram que as irradiações laterais dos simuladores UF na postura sentada oferecem uma distribuição de dose menos uniforme se comparado às irradiações AP/PA com o simulador na postura deitada. Para a geometria de irradiação PA a dose absorvida na medula vermelha é aproximadamente 20% maior que na projeção AP, o que sugere que o primeiro caso seja mais adequado para a destruição da medula doente. Quanto ao uso de objetos compensadores para atenuação da radiação no pulmão houve uma redução da dose absorvida por esse órgão em 23%, o que mostra sua eficácia e importância para esses procedimentos. Também foi observado que a diminuição da distância de tratamento do paciente a fonte de radiação e das paredes da sala leva a um aumento próximo de 10% e de 5%, respectivamente, na dose absorvida, o que sugere que sejam mais adequados tratamentos realizados a grandes distâncias foco-superfície e distantes das paredes da sala. Quanto à energia do feixe utilizado para Irradiação de Corpo Inteiro, as diferenças mais significativas entre o Cobalto-60 e o espectro do acelerador linear de 6 MV foram de até 46,23%, o que ocorreu para a geometria de irradiação PA, onde é observado que o primeiro deposita a maior parte de sua energia próximo a superfície, o que mostra que feixes mais energéticos são mais eficazes para irradiação em profundidades maiores. Outro fator analisado foi a combinação de campos adjacentes e sobrepostos para o tratamento, o que levou a superdosagens em alguns órgãos e comprometeu a uniformidade da dose assim como observado por outros autores. Os cálculos da dose efetiva permitiram concluir que há um maior comprometimento geral do corpo para irradiações na geometria de incidência LLAT. Também foi encontrado que a dose efetiva é superior na projeção AP que em PA assim como encontrado na literatura. As análises feitas mostram a importância e sugerem um estudo mais detalhado das condições de exposição para o planejamento de tratamentos por TBI.

In dieser Arbeit betrachten wir das Strömungs-Diffusions-(Reaktions)-Problem für passive Markerteilchen, die in zweidimensionalen laminaren Strömungsmustern mit geringem thermischem Rauschen gelöst sind. Der deterministische Fluss umfasst Zellen in Form von Quadraten oder Katzenaugen. In ihnen tritt Rotationsbewegung auf. Einige der Strömungen bestehen aus wellenförmigen Bereichen mit gerader Vorwärtsbewegung. Alle Systeme sind entweder periodisch oder durch Wände begrenzt. Eine untersuchte Familie von Strömungen interpoliert kontinuierlich zwischen Reihen von Wirbeln und Scherflüssen. Wir analysieren zahlreiche numerische Simulationen, die bisherige theoretische Vorhersagen bestätigen und neue Phänomene offenbaren. Ohne Rauschen sind die Teilchen in einzelnen Bestandteilen des Flusses für immer gefangen. Durch Hinzufügen von schwachem thermischen Rauschen wird die normale Diffusion für lange Zeiten stark verstärkt und führt zu verschiedenen Diffusionsarten für mittlere Zeiten. Mit Continuous-Time-Random-Walk-Modellen leiten wir analytische Ausdrücke in Übereinstimmung mit den numerischen Ergebnissen her, die je nach Parametern, Anfangsbedingungen und Alterungszeiten von subdiffusiver bis superballistischer anomaler Diffusion für mittlere Zeiten reichen. Wir sehen deutlich, dass einige der früheren Vorhersagen nur für Teilchen gelten, die an der Separatrix des Flusses starten - der einzige Fall, der in der Vergangenheit ausführlich betrachtet wurde - und dass das System zu vollkommen anderem Verhalten in anderen Situationen führen kann, einschließlich einem Schwingenden beim Start im Zentrum einesWirbels nach einer gewissen Alterungszeit. Darüber hinaus enthüllen die Simulationen, dass Teilchenreaktionen dort häufiger auftreten, wo sich die Geschwindigkeit der Strömung stark ändert, was dazu führt, dass langsame Teilchen von schnelleren getroffen werden, die ihnen folgen. Die umfangreichen numerischen Simulationen, die für diese Arbeit durchgeführt wurden, mussten jetzt durchgeführt werden, da wir die Rechenleistung dafür besitzen. / In this thesis, we consider the advection-diffusion-(reaction) problem for passive tracer particles suspended in two-dimensional laminar flow patterns with small thermal noise. The deterministic flow comprises cells in the shape of either squares or cat’s eyes. Rotational motion occurs inside them. Some of the flows consist of sinusoidal regions of straight forward motion. All systems are either periodic or are bounded by walls. One examined family of flows continuously interpolates between arrays of eddies and shear flows. We analyse extensive numerical simulations, which confirm previous theoretical predictions as well as reveal new phenomena. Without noise, particles are trapped forever in single building blocks of the flow. Adding small thermal noise, leads to largely enhanced normal diffusion for long times and several kinds of diffusion for intermediate times. Using continuous time random walk models, we derive analytical expressions in accordance with numerical results, ranging from subdiffusive to superballistic anomalous diffusion for intermediate times depending on parameters, initial conditions and aging time. We clearly see, that some of the previous predictions are only true for particles starting at the separatrix of the flow - the only case considered in depth in the past - and that the system might show a vastly different behavior in other situations, including an oscillatory one, when starting in the center of an eddy after a certain aging time. Furthermore, simulations reveal that particle reactions occur more frequently at positions where the velocity of the flow changes the most, resulting in slow particles being hit by faster ones following them. The extensive numerical simulations performed for this thesis had to be done now that we have the computational means to do so. Machines are powerful tools in order to gain a deeper and more detailed insight into the dynamics of many complicated dynamical and stochastic systems.

The purpose of this thesis was to develop an economical, sustainable, and environmentally friendly straw Medium Density Fibreboard (MDF) process, capable of full-scale manufacturing and to produce MDF of requested quality. The investigated straw was based on wheat (Triticum aestivum L.) and rice (Oryzae sativa L.). In this thesis three different methods were taken for manufacture of straw MDF; (A) wheat-straw fibre was blowline blended with melamine-modified urea-formaldehyde (MUF), (B) rice-straw fibre was mixed with methylene diphenyl diisocyanate (MDI) in a resin drum-blender, and (C) wheat-straw fibre was activated in the blowline by the addition of Fenton’s reagent (H2O2/Fe2+) for production of non-resin MDF panels.  The MUF/wheat straw MDF panels were approved according to the requirements of the EN standard for MDF (EN 622-5, 2006). The MDI/rice-straw MDF panels were approved according to requirements of the standard for MDF of the American National Standard Institute (ANSI A208.2-2002). The non-resin wheat-straw panels showed mediocre MDF panel properties and were not approved according to the requirements in the MDF standard. The dry process for wood-based MDF was modified for production of straw MDF. The straw MDF process was divided into seven main process steps. 1.       Size-reduction (hammer-milling) and screening of straw 2.       Wetting and heating of straw 3.       Defibration 4.       Resination of straw fibre 5.       Mat forming 6.       Pre-pressing 7.       Hot-pressing       The primary results were that the straw MDF process was capable of providing satisfactory straw MDF panels based on different types of straw species and adhesives. Moreover, the straw MDF process was performed in pilot-plant scale and demonstrated as a suitable method for producing straw MDF from straw bales to finished straw MDF panels. In the environmental perspective the agricultural straw-waste is a suitable source for producing MDF to avoid open field burning and to capture carbon dioxide (CO2), the biological sink for extended time into MDF panels, instead of converting straw directly into bio energy or applying straw fibre a few times as recycled paper. Additionally, the straw MDF panels can be recycled or converted to energy after utilization. A relationship between water retention value (WRV) of resinated straw fibres, the thickness swelling of corresponding straw MDF panels, and the amount of applied adhesive was determined. WRV of the straw fibre increased and the TS of straw MDF declined as a function of the resin content. The empirical models developed were of acceptable significance and the R2 values were 0.69 (WRV) and 0.75 (TS), respectively. Reduced thickness swelling of MDF as the resin content is increased is well-known. The increase of WRV as a function of added polymers is not completely established within the science of fibre swelling. Fortunately, more fundamental research can be initiated and likely a simple method for prediction of thickness swelling of MDF by analysis of the dried and resinated MDF fibres is possible. / Syftet med denna avhandling var att lägga grunden för en ekonomisk, hållbar och miljövänlig MDF process för halmråvara, kapabel för fullskalig produktion av MDF och goda skivegenskaper. Framställningen av MDF skivor utgick från halm av vete (Triticum aestivum L.) och ris (Oryzae sativa L.). Tre olika metoder användes för att producera MDF av halm; (A) fibrer av vetehalm belimmades i blåsledning med ett melaminmodifierat urea-formaldehydlim (MUF), (B) fibrer av rishalm belimmades i en limblandare med metylen difenyl diisocyanate (MDI), (C) Limfria MDF skivor av vetehalm framställdes med aktivering av fibrer genom tillsats av Fenton´s reagens (H2O2/Fe2+) i blåsledning utan någon tillsats av syntetiskt lim. Sammanfattningsvis kan det understrykas att framställda MDF-skivor av MUF/vetehalm var godkända enligt standard för MDF (EN 622-5, 2006). Dessutom var framställda MDF skivor av MDI/rishalm också godkända enligt krav i standard för MDF ”American National Standard Institute” (ANSI A2008.2-2002). Limfria vetehalmskivor visade på måttliga skivegenskaper och klarade inte kraven i MDF standard.   Fiberframställningsprocessen för MDF modifierades till en produktion utgående från halm. MDF processen för halm delades upp i sju primära processoperationer.   (1)            Storleksreducering och sållning av halm (2)            Vätning och uppvärmning av halm (3)            Defibrering (4)            Belimning av halmfiber (5)            Mattformning (6)            Förpressning (7)            Pressning   De viktigaste resultaten från denna studie är att MDF av halm kunde produceras utgående från olika typer av halmsorter och lim. Dessutom utfördes MDF-processen i pilotskala och visade på en lämplig metod för framställning av MDF-skivor från halmbalar till färdiga halmfiberskivor. Det miljömässiga perspektivet på att använda jordbruksavfall till framställning av halmskivor är att undvika förbränning av halm ute på fältet, men det är även möjligt att binda koldioxid (CO2) i halmskivor under längre tid än att omsätta halmråvaran omedelbart som bioenergi eller använda halmfiber som returpapper några få gånger. Dessutom kan MDF återanvändas eller bli omsatt till energi efter användning.   Ett förhållande mellan ”water retention value” (WRV), av belimmade halmfiber, tjocklekssvällning för motsvarande MDF av halmskivor och mängden av tillsatt lim vid olika nivåer har undersökts. Med ökande limhalt tilltog WRV fibersvällning, vidare minskade tjocklekssvällning för motsvarande MDF skivor. De framtagna empiriska modellerna var godtagbara och beräknade R2 värden var 0.69 (WRV) och 0.75 (TS). Minskad tjocklekssvällning med ökad limhalt är dokumenterad sen tidigare. Ökad fibersvällning WRV vid tillsats av polymerer (limmer) är inte fullständigt etablerad inom vetenskapen för fibersvällning. Lyckligtvis kan grundläggande forskning initieras och sannolikt föreligger en enkel metod för att prediktera tjocklekssvällning av MDF genom analyser av torkade och belimmad MDF fiber.

The aim of this study is to gain more in-depth knowledge into what Swedish upper secondary school students perceive they learn, and the factors that students perceive affect learning, when they start and run mini-companies within the Junior Achievement Company Program.  The data is comprised of interviews with eleven students each of whom ran a mini-company with other students. Situated learning theory, experiential learning theory and theoretical concepts on reflection in learning were used to analyze and further understand the data. The results reveal that the students talk about, and appear to convey, equal importance upon learning general skills as learning business skills when doing their mini-companies. Students describe using general skills they improved while running their mini-companies in other school activities and non-school activities leading to better performance in these activities. Doing business activities triggers learning and provides students with an opportunity to further develop, and learn multiple aspects, of skills. Students identify many factors, such as time, autonomy, assessment, and deadlines, which they associate with their mini-companies. On the whole, they say these factors have a positive effect on learning both business and general skills, however some factors can also inhibit learning. An analysis of all the factors students identified reveals that they originate, or are influenced by, multiple contexts such as school, the Swedish Junior Achievement organization, and the business environment. Together these factors can be said to create a special school community of practice for their mini-company project. Students point out significant differences between their mini-company project, and other school projects they have previously done, thus providing valuable insight into the importance of project design in relation to learning skills and possible pedagogical implications regarding learning general skills in other school projects. / This thesis strives to gain further knowledge and understanding into what Swedish upper secondary students perceive they learn, and how they learn, when starting and running Junior Achievement mini-companies. The data is comprised of interviews with eleven students each of whom ran a mini-company with other students. Situated learning theory, experiential learning theory and theoretical concepts on reflection on learning were used to analyze and further understand the data. The results reveal that students talk about, and appear to convey, equal importance upon learning general and business skills. General skills students improved when doing mini-companies can benefit other school and non-school activities. Students perceive that learning is not only triggered by the business tasks they do, but is also influenced by a multitude of factors such as time, autonomy, assessment, and deadlines that affect what, and how they learn. Overall, students perceive factors that they associate with the mini-company project have a positive effect on learning skills, however some can also inhibit learning. Students point out many differences between the mini-company project and other school projects providing valuable insight into the importance of project design in relation to learning skills.

The aim of this study is to gain more in-depth knowledge into what Swedish upper secondary school students perceive they learn, and the factors that students perceive affect learning, when they start and run mini-companies within the Junior Achievement Company Program.  The data is comprised of interviews with eleven students each of whom ran a mini-company with other students. Situated learning theory, experiential learning theory and theoretical concepts on reflection in learning were used to analyze and further understand the data. The results reveal that the students talk about, and appear to convey, equal importance upon learning general skills as learning business skills when doing their mini-companies. Students describe using general skills they improved while running their mini-companies in other school activities and non-school activities leading to better performance in these activities. Doing business activities triggers learning and provides students with an opportunity to further develop, and learn multiple aspects, of skills. Students identify many factors, such as time, autonomy, assessment, and deadlines, which they associate with their mini-companies. On the whole, they say these factors have a positive effect on learning both business and general skills, however some factors can also inhibit learning. An analysis of all the factors students identified reveals that they originate, or are influenced by, multiple contexts such as school, the Swedish Junior Achievement organization, and the business environment. Together these factors can be said to create a special school community of practice for their mini-company project. Students point out significant differences between their mini-company project, and other school projects they have previously done, thus providing valuable insight into the importance of project design in relation to learning skills and possible pedagogical implications regarding learning general skills in other school projects. / This thesis strives to gain further knowledge and understanding into what Swedish upper secondary students perceive they learn, and how they learn, when starting and running Junior Achievement mini-companies. The data is comprised of interviews with eleven students each of whom ran a mini-company with other students. Situated learning theory, experiential learning theory and theoretical concepts on reflection on learning were used to analyze and further understand the data. The results reveal that students talk about, and appear to convey, equal importance upon learning general and business skills. General skills students improved when doing mini-companies can benefit other school and non-school activities. Students perceive that learning is not only triggered by the business tasks they do, but is also influenced by a multitude of factors such as time, autonomy, assessment, and deadlines that affect what, and how they learn. Overall, students perceive factors that they associate with the mini-company project have a positive effect on learning skills, however some can also inhibit learning. Students point out many differences between the mini-company project and other school projects providing valuable insight into the importance of project design in relation to learning skills.