This thesis deals with the cartilage imaging using magnetic resonance. At first, there is mentioned physical principle of the magnetic resonance phenomenon and the most commonly used excitation sequences, followed by the description of the 9.4 T MR imaging system Bruker BioSpec 94/30 USR, which was used for measurement in the practical part. The next part is dedicated to the composition of cartilages and describes the temporomandibular joint, due to its suitability as an object for cartilage imaging. The series of MR scans of temporomandibular joint were taken with different acquisition parameters and evaluated by program designed through the MATLAB software. The program can be used for viewing scanned images, evaluating their contrast and determining the T1 relaxation time of the tissues by creating T1 maps.

[EN] Multiple-Input Multiple-Output (MIMO) technology in Digital Terrestrial Television (DTT) networks has the potential to increase the spectral efficiency and improve network coverage to cope with the competition of limited spectrum use (e.g., assignment of digital dividend and spectrum demands of mobile broadband), the appearance of new high data rate services (e.g., ultra-high definition TV - UHDTV), and the ubiquity of the content (e.g., fixed, portable, and mobile). It is widely recognised that MIMO can provide multiple benefits such as additional receive power due to array gain, higher resilience against signal outages due to spatial diversity, and higher data rates due to the spatial multiplexing gain of the MIMO channel. These benefits can be achieved without additional transmit power nor additional bandwidth, but normally come at the expense of a higher system complexity at the transmitter and receiver ends. The final system performance gains due to the use of MIMO directly depend on physical characteristics of the propagation environment such as spatial correlation, antenna orientation, and/or power imbalances experienced at the transmit aerials. Additionally, due to complexity constraints and finite-precision arithmetic at the receivers, it is crucial for the overall system performance to carefully design specific signal processing algorithms. This dissertation focuses on transmit and received signal processing for DTT systems using MIMO-BICM (Bit-Interleaved Coded Modulation) without feedback channel to the transmitter from the receiver terminals. At the transmitter side, this thesis presents investigations on MIMO precoding in DTT systems to overcome system degradations due to different channel conditions. At the receiver side, the focus is given on design and evaluation of practical MIMO-BICM receivers based on quantized information and its impact in both the in-chip memory size and system performance. These investigations are carried within the standardization process of DVB-NGH (Digital Video Broadcasting - Next Generation Handheld) the handheld evolution of DVB-T2 (Terrestrial - Second Generation), and ATSC 3.0 (Advanced Television Systems Committee - Third Generation), which incorporate MIMO-BICM as key technology to overcome the Shannon limit of single antenna communications. Nonetheless, this dissertation employs a generic approach in the design, analysis and evaluations, hence, the results and ideas can be applied to other wireless broadcast communication systems using MIMO-BICM. / [ES] La tecnología de múltiples entradas y múltiples salidas (MIMO) en redes de Televisión Digital Terrestre (TDT) tiene el potencial de incrementar la eficiencia espectral y mejorar la cobertura de red para afrontar las demandas de uso del escaso espectro electromagnético (e.g., designación del dividendo digital y la demanda de espectro por parte de las redes de comunicaciones móviles), la aparición de nuevos contenidos de alta tasa de datos (e.g., ultra-high definition TV - UHDTV) y la ubicuidad del contenido (e.g., fijo, portable y móvil). Es ampliamente reconocido que MIMO puede proporcionar múltiples beneficios como: potencia recibida adicional gracias a las ganancias de array, mayor robustez contra desvanecimientos de la señal gracias a la diversidad espacial y mayores tasas de transmisión gracias a la ganancia por multiplexado del canal MIMO. Estos beneficios se pueden conseguir sin incrementar la potencia transmitida ni el ancho de banda, pero normalmente se obtienen a expensas de una mayor complejidad del sistema tanto en el transmisor como en el receptor. Las ganancias de rendimiento finales debido al uso de MIMO dependen directamente de las características físicas del entorno de propagación como: la correlación entre los canales espaciales, la orientación de las antenas y/o los desbalances de potencia sufridos en las antenas transmisoras. Adicionalmente, debido a restricciones en la complejidad y aritmética de precisión finita en los receptores, es fundamental para el rendimiento global del sistema un diseño cuidadoso de algoritmos específicos de procesado de señal. Esta tesis doctoral se centra en el procesado de señal, tanto en el transmisor como en el receptor, para sistemas TDT que implementan MIMO-BICM (Bit-Interleaved Coded Modulation) sin canal de retorno hacia el transmisor desde los receptores. En el transmisor esta tesis presenta investigaciones en precoding MIMO en sistemas TDT para superar las degradaciones del sistema debidas a diferentes condiciones del canal. En el receptor se presta especial atención al diseño y evaluación de receptores prácticos MIMO-BICM basados en información cuantificada y a su impacto tanto en la memoria del chip como en el rendimiento del sistema. Estas investigaciones se llevan a cabo en el contexto de estandarización de DVB-NGH (Digital Video Broadcasting - Next Generation Handheld), la evolución portátil de DVB-T2 (Second Generation Terrestrial), y ATSC 3.0 (Advanced Television Systems Commitee - Third Generation) que incorporan MIMO-BICM como clave tecnológica para superar el límite de Shannon para comunicaciones con una única antena. No obstante, esta tesis doctoral emplea un método genérico tanto para el diseño, análisis y evaluación, por lo que los resultados e ideas pueden ser aplicados a otros sistemas de comunicación inalámbricos que empleen MIMO-BICM. / [CA] La tecnologia de múltiples entrades i múltiples eixides (MIMO) en xarxes de Televisió Digital Terrestre (TDT) té el potencial d'incrementar l'eficiència espectral i millorar la cobertura de xarxa per a afrontar les demandes d'ús de l'escàs espectre electromagnètic (e.g., designació del dividend digital i la demanda d'espectre per part de les xarxes de comunicacions mòbils), l'aparició de nous continguts d'alta taxa de dades (e.g., ultra-high deffinition TV - UHDTV) i la ubiqüitat del contingut (e.g., fix, portàtil i mòbil). És àmpliament reconegut que MIMO pot proporcionar múltiples beneficis com: potència rebuda addicional gràcies als guanys de array, major robustesa contra esvaïments del senyal gràcies a la diversitat espacial i majors taxes de transmissió gràcies al guany per multiplexat del canal MIMO. Aquests beneficis es poden aconseguir sense incrementar la potència transmesa ni l'ample de banda, però normalment s'obtenen a costa d'una major complexitat del sistema tant en el transmissor com en el receptor. Els guanys de rendiment finals a causa de l'ús de MIMO depenen directament de les característiques físiques de l'entorn de propagació com: la correlació entre els canals espacials, l'orientació de les antenes, i/o els desequilibris de potència patits en les antenes transmissores. Addicionalment, a causa de restriccions en la complexitat i aritmètica de precisió finita en els receptors, és fonamental per al rendiment global del sistema un disseny acurat d'algorismes específics de processament de senyal. Aquesta tesi doctoral se centra en el processament de senyal tant en el transmissor com en el receptor per a sistemes TDT que implementen MIMO-BICM (Bit-Interleaved Coded Modulation) sense canal de tornada cap al transmissor des dels receptors. En el transmissor aquesta tesi presenta recerques en precoding MIMO en sistemes TDT per a superar les degradacions del sistema degudes a diferents condicions del canal. En el receptor es presta especial atenció al disseny i avaluació de receptors pràctics MIMO-BICM basats en informació quantificada i al seu impacte tant en la memòria del xip com en el rendiment del sistema. Aquestes recerques es duen a terme en el context d'estandardització de DVB-NGH (Digital Video Broadcasting - Next Generation Handheld), l'evolució portàtil de DVB-T2 (Second Generation Terrestrial), i ATSC 3.0 (Advanced Television Systems Commitee - Third Generation) que incorporen MIMO-BICM com a clau tecnològica per a superar el límit de Shannon per a comunicacions amb una única antena. No obstant açò, aquesta tesi doctoral empra un mètode genèric tant per al disseny, anàlisi i avaluació, per la qual cosa els resultats i idees poden ser aplicats a altres sistemes de comunicació sense fils que empren MIMO-BICM. / Vargas Paredero, DE. (2016). Transmit and Receive Signal Processing for MIMO Terrestrial Broadcast Systems [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/66081 / Premios Extraordinarios de tesis doctorales

Text in Afrikaans / Summaries in Afrikaans and English / This study aims to investigate and explain how the L2 -facilitator can effectively employ the various facilitation skills of language teaching in Afrikaans Second Language within the Outcomes Based Education framework in the learner-centred classroom. The facilitator is critical in providing an opportunity for multicultural learners to develop the necessary language learning skills to enjoy Afrikaans Second Language/Additional Language learning as an interesting learning experience within a positive learning milieu. In the learner-centred U -classroom, learners too must accept responsibility for their own and their peers' learning within the co-operative learning group. This study reveals how the L2 -facilitator can develop the necessary knowledge and skills concerning groupwork, such as the strategies enhancing L 2 -learning, effective group facilitation skills, learner attitudes towards the facilitator, problem-solving skills, co-operative learning as a control technique, communication, learners' behaviour and the advantages of groupwork. Furthermore, elements of classroom negotiation and the facilitator's methods of working in this negotiated partnership are also discussed. Since language learning is integral to lifelong learning, multicultural learners must be motivated to learn Afrikaans Second/ Additional language with greater enthusiasm. This necessitates the L2 -facilitator creating an interesting, challenging and authentic language learning environment where mutual respect and trust are emphasised. This study reveals how the L2 -facilitator could develop his/her knowledge of task-based L2 -teaching and use it with the effective techniques of facilitation and negotiation skills in the taskorientated second language classroom to lead learners to effective Afrikaans L2 -learning. The new National Language Standardisation Policy 200112002 necessitates the facilitator of Afrikaans L 2 -teaching/learning within the Outcomes Based Education framework and the revised Curriculum 2005 to be aufait with assessment and his/her role in assessment. Being knowledgeable on the various criteria and strategies regarding assessment is therefore imperative. Finally, chapter five illustrates practically how the facilitator could plan, organise, base, integrate and present authentic Afrikaans L 2 -lessons/work based on the theoretical knowledge and aspects of facilitation skills, group-work, task-based learning and assessment discussed in chapters two to four. / Daar word in die studie gepoog om te ondersoek en te verduidelik hoe die T2-fasiliteerder die verskillende fasiliteringsvaardighede ten opsigte van T2 -Afrikaansonderrig binne die UGO -raamwerk in die leerdergesentreerde T2-klaskamer effektief kan gebruik. Die fasiliteerder behoort sy multikulturele leerders die geleentheid te gun om die nodige taalleervaardighede te ontwikkel sodat hulle Afrikaans Tweedetaalleer/ Addisionele Taalleer as 'n interessante leerervaring binne 'n positiewe leerklimaat kan geniet. In die leerdergesentreerde T2 -klaskamer moet die leerders ook die verantwoordelikheid vir bulle eie leer, en vir die leer van ander leerders binne kooperatiewe leergroepe kan aanvaar. Die wyse waarop die fasiliteerder van T2-leer die nodige kennis en vaardighede ten opsigte van groepwerk kan ontwikkel, word deur die studie aan die lig gebring. Die verskillende strategiee wat die aanleer van die tweedetaal binne groepwerk bevorder, effektiewe groepsfasiliteringsvaardighede, leerders se gesindhede teenoor die fasiliteerder, die probleemoplossingsvaardighede, kooperatiewe leer as beheertegniek, kommunikasie, leerdergedragswyses en die voordele van groepwerk kom aan bod. Elemente van klaskameronderhandeling en die fasiliteerder se werkswyse in die onderhandelingsvennootskap word ook bespreek. Aangesien taalleer 'n integrale faset van lewenslange leer vorm, moet multikulturele leerders gemotiveer word om Afrikaans Tweedetaal/ Addisionele Taal op 'n meer entoesiastiese wyse te kan leer. Die T2 -fasiliteerder moet 'n interessante, uitdagende, outentieke taalleeromgewing skep waarin wedersydse respek en vertroue beklemtoon word. Die studie toon die wyse aan waarop die T2 -fasiliteerder sylhaar kennis in verband met taakgerigte T2 -onderrig kan ontwikkel en dit met die effektiewe fasiliteringstegnieke en onderhandelingsvaardighede in die taakgeorienteerde T2-klaskamer kan kombineer en gebruik om leerders tot effektiewe T2 -Afrikaansleer/ Addisionele Taalleer te kan lei. Die nuwe Nasionale Taalstandaardiseringsbeleid 2001/2002 vereis dat die fasiliteerder van T2-Afrikaansonderrig/-leer binne die UGO -raamwerk en die hersiene Kurrikulum 2005 deeglike kennis moet dra van assessering en sylhaar rol in assessering. Deeglike kennis ten opsigte van die verskillende assesseringskriteria en assesseringstegnieke is dus noodsaaklik. Daar word in hoofstuk vyf aangetoon op watter wyse die fasiliteerder outentieke praktiese T2-Afrikaanslesse/-werk, kan beplan, organiseer en dit op die teoretiese kennis en aspekte ten opsigte van fasiliteringsvaardighede, groepwerk, taakgerigte leer en assessering wat in hoofstukke twee tot vier bespreek word, kan toepas en geintegreerd kan aanbied. / Afrikaans and Theory of Literature / D.Litt. et Phil. (Afrikaans)

Text in Afrikaans / Summaries in Afrikaans and English / This study aims to investigate and explain how the L2 -facilitator can effectively employ the various facilitation skills of language teaching in Afrikaans Second Language within the Outcomes Based Education framework in the learner-centred classroom. The facilitator is critical in providing an opportunity for multicultural learners to develop the necessary language learning skills to enjoy Afrikaans Second Language/Additional Language learning as an interesting learning experience within a positive learning milieu. In the learner-centred U -classroom, learners too must accept responsibility for their own and their peers' learning within the co-operative learning group. This study reveals how the L2 -facilitator can develop the necessary knowledge and skills concerning groupwork, such as the strategies enhancing L 2 -learning, effective group facilitation skills, learner attitudes towards the facilitator, problem-solving skills, co-operative learning as a control technique, communication, learners' behaviour and the advantages of groupwork. Furthermore, elements of classroom negotiation and the facilitator's methods of working in this negotiated partnership are also discussed. Since language learning is integral to lifelong learning, multicultural learners must be motivated to learn Afrikaans Second/ Additional language with greater enthusiasm. This necessitates the L2 -facilitator creating an interesting, challenging and authentic language learning environment where mutual respect and trust are emphasised. This study reveals how the L2 -facilitator could develop his/her knowledge of task-based L2 -teaching and use it with the effective techniques of facilitation and negotiation skills in the taskorientated second language classroom to lead learners to effective Afrikaans L2 -learning. The new National Language Standardisation Policy 200112002 necessitates the facilitator of Afrikaans L 2 -teaching/learning within the Outcomes Based Education framework and the revised Curriculum 2005 to be aufait with assessment and his/her role in assessment. Being knowledgeable on the various criteria and strategies regarding assessment is therefore imperative. Finally, chapter five illustrates practically how the facilitator could plan, organise, base, integrate and present authentic Afrikaans L 2 -lessons/work based on the theoretical knowledge and aspects of facilitation skills, group-work, task-based learning and assessment discussed in chapters two to four. / Daar word in die studie gepoog om te ondersoek en te verduidelik hoe die T2-fasiliteerder die verskillende fasiliteringsvaardighede ten opsigte van T2 -Afrikaansonderrig binne die UGO -raamwerk in die leerdergesentreerde T2-klaskamer effektief kan gebruik. Die fasiliteerder behoort sy multikulturele leerders die geleentheid te gun om die nodige taalleervaardighede te ontwikkel sodat hulle Afrikaans Tweedetaalleer/ Addisionele Taalleer as 'n interessante leerervaring binne 'n positiewe leerklimaat kan geniet. In die leerdergesentreerde T2 -klaskamer moet die leerders ook die verantwoordelikheid vir bulle eie leer, en vir die leer van ander leerders binne kooperatiewe leergroepe kan aanvaar. Die wyse waarop die fasiliteerder van T2-leer die nodige kennis en vaardighede ten opsigte van groepwerk kan ontwikkel, word deur die studie aan die lig gebring. Die verskillende strategiee wat die aanleer van die tweedetaal binne groepwerk bevorder, effektiewe groepsfasiliteringsvaardighede, leerders se gesindhede teenoor die fasiliteerder, die probleemoplossingsvaardighede, kooperatiewe leer as beheertegniek, kommunikasie, leerdergedragswyses en die voordele van groepwerk kom aan bod. Elemente van klaskameronderhandeling en die fasiliteerder se werkswyse in die onderhandelingsvennootskap word ook bespreek. Aangesien taalleer 'n integrale faset van lewenslange leer vorm, moet multikulturele leerders gemotiveer word om Afrikaans Tweedetaal/ Addisionele Taal op 'n meer entoesiastiese wyse te kan leer. Die T2 -fasiliteerder moet 'n interessante, uitdagende, outentieke taalleeromgewing skep waarin wedersydse respek en vertroue beklemtoon word. Die studie toon die wyse aan waarop die T2 -fasiliteerder sylhaar kennis in verband met taakgerigte T2 -onderrig kan ontwikkel en dit met die effektiewe fasiliteringstegnieke en onderhandelingsvaardighede in die taakgeorienteerde T2-klaskamer kan kombineer en gebruik om leerders tot effektiewe T2 -Afrikaansleer/ Addisionele Taalleer te kan lei. Die nuwe Nasionale Taalstandaardiseringsbeleid 2001/2002 vereis dat die fasiliteerder van T2-Afrikaansonderrig/-leer binne die UGO -raamwerk en die hersiene Kurrikulum 2005 deeglike kennis moet dra van assessering en sylhaar rol in assessering. Deeglike kennis ten opsigte van die verskillende assesseringskriteria en assesseringstegnieke is dus noodsaaklik. Daar word in hoofstuk vyf aangetoon op watter wyse die fasiliteerder outentieke praktiese T2-Afrikaanslesse/-werk, kan beplan, organiseer en dit op die teoretiese kennis en aspekte ten opsigte van fasiliteringsvaardighede, groepwerk, taakgerigte leer en assessering wat in hoofstukke twee tot vier bespreek word, kan toepas en geintegreerd kan aanbied. / Afrikaans and Theory of Literature / D.Litt. et Phil. (Afrikaans)

No description available.

In 2008, the European Digital Video Broadcasting (DVB) standardization committee issued the second generation of Digital Video Broadcasting-Terrestrial (DVB-T2) standard in order to enable the wide broadcasting of high definition and 3D TV programmes. DVB-T2 has adopted several new technologies to provide more robust reception compared to the first genaration standard. One important technology is the bit interleaved coded modulation (BICM) with doubled signal space diversity plus the usage of low-density parity check (LDPC) codes. Both techniques can be combined at the receiver side through an iterative process between the decoder and demapper in order to further increase the system performance. The object of my study was to design and prototype a DVB-T2 receiver which supports iterative process. The two main contributions to the demapper design are the proposal of a linear approximation of Euclidean distance computation and the derivation of a sub-region detection algorithm for the two-dimensional demapper. Both contributions allows the computational complexity of the demapper to be reduced for its hardware implementation. In order to enable iterative processing between the demapper and the decoder, we investigated the use of vertical shuffled Min-Sum LDPC decoding algorithm. A novel vertical shuffled iterative structure aiming at reducing the latency of iterative processing and the corresponding architecture of the decoder were proposed. The proposed demapper and decoder have been integrated in a real DVB-T2 demodulator and tested in order to validate the efficiency of the proposed architecture. The prototype of a simplified DVB-T2 transceiver has been implemented, in which the receiver supports both non-iterative process and iterative process. We published the first paper related to a DVB-T2 iterative receiver.

Treatment of patients with multiple sclerosis (MS) and development of new therapies have been challenging due to the disease complexity and slow progression, and the limited sensitivity of available clinical outcomes. Modeling and simulation has become an increasingly important component in drug development and in post-marketing optimization of use of medication. This thesis focuses on development of pharmacometric models for characterization and quantification of the relationships between drug exposure, biomarkers and clinical endpoints in relapse-remitting MS (RRMS) following cladribine treatment. A population pharmacokinetic model of cladribine and its main metabolite, 2-chloroadenine, was developed using plasma and urine data. The renal clearance of cladribine was close to half of total elimination, and was found to be a linear function of creatinine clearance (CRCL). Exposure-response models could quantify a clear effect of cladribine tablets on absolute lymphocyte count (ALC), burden of disease (BoD), expanded disability status scale (EDSS) and relapse rate (RR) endpoints. Moreover, they gave insight into disease progression of RRMS. This thesis further demonstrates how integrated modeling framework allows an understanding of the interplay between ALC and clinical efficacy endpoints. ALC was found to be a promising predictor of RR. Moreover, ALC and BoD were identified as predictors of EDSS time-course. This enables the understanding of the behavior of the key outcomes necessary for the successful development of long-awaited MS therapies, as well as how these outcomes correlate with each other. The item response theory (IRT) methodology, an alternative approach for analysing composite scores, enabled to quantify the information content of the individual EDSS components, which could help improve this scale. In addition, IRT also proved capable of increasing the detection power of potential drug effects in clinical trials, which may enhance drug development efficiency. The developed nonlinear mixed-effects models offer a platform for the quantitative understanding of the biomarker(s)/clinical endpoint relationship, disease progression and therapeutic response in RRMS by integrating a significant amount of knowledge and data.

This study offers an ecumenical exploration of human transformation through the examination of this topic in the thought of Karl Barth (1888-1968), a Swiss Reformed theologian; Joseph Ratzinger (b. 1927), a Roman Catholic theologian; and John Zizioulas (b. 1931), a Greek Orthodox theologian. Describing and understanding human transformation stands as a crucial task for theology because no one is simply born a Christian—in order to be a Christian one must become a Christian. The first chapter introduces this topic, the three theologians (highlighting their commonalities), and the three questions that guide the analysis of each theologian and the thesis as a whole: What is the goal of human transformation? What is the basis of human transformation? How are humans transformed? Chapters 2, 3, and 4 treat the topic of human transformation in the theology of Barth, Ratzinger, and Zizioulas, respectively. All three understand the goal of human transformation to be the prayer of the children of God, and locate its basis in God’s reconciling act in Jesus Christ—an act itself based in the primordial divine decision to be God pro nobis. Even within this broad agreement, however, differences are evident, especially with regard to eschatology. Consideration of how this transformation occurs reveals significant differences concerning the agency of Jesus Christ in relation to the Holy Spirit and the church. The final chapter explores 1) the convergences and divergences between Barth, Ratzinger, and Zizioulas regarding human transformation; 2) the contributions of this study to the interpretation of Barth, Ratzinger, and Zizioulas; and 3) the relationship between human transformation and participation in God. Throughout, attention is given to the relationship between Jesus Christ, the Holy Spirit, the church, the eschaton, and the triunity of God and human transformation. All three accounts of human transformation point beyond the transition between sinful and redeemed humanity to a dynamic anthropology in which the constant asking, receiving, thanking, and asking again is the very “ontological location” of the eschatological life of humanity: our being is in becoming.

Magnetic resonance imaging (MRI) is one of the most important diagnostic tools of modern healthcare. The signal in medical MRI predominantly originates from water and fat molecules. Separation of the two components into water-only and fat-only images can improve diagnosis, and is the premier non-invasive method for measuring the amount and distribution of fatty tissue. Fat-water imaging (FWI) enables fast fat/water separation by model-based estimation from chemical shift encoded data, such as multi-echo acquisitions. Qualitative FWI is sufficient for visual separation of the components, while quantitative FWI also offers reliable estimates of the fat percentage in each pixel. The major problems of current FWI methods are long acquisition times, long reconstruction times, and reconstruction errors that degrade image quality. In this thesis, existing FWI methods were reviewed, and novel fully automatic methods were developed and evaluated, with a focus on fast 3D image reconstruction. All MRI data was acquired on standard clinical scanners. A triple-echo qualitative FWI method was developed for the specific application of 3D whole-body imaging. The method was compared with two reference methods, and demonstrated superior image quality when evaluated in 39 volunteers. The problem of qualitative FWI by dual-echo data with unconstrained echo times was solved, allowing faster and more flexible image acquisition than conventional FWI. Feasibility of the method was demonstrated in three volunteers and the noise performance was evaluated. Further, a quantitative multi-echo FWI method was developed. The signal separation was based on discrete whole-image optimization. Fast 3D image reconstruction with few reconstruction errors was demonstrated by abdominal imaging of ten volunteers. Lastly, a method was proposed for quantitative mapping of average fatty acid chain length and degree of saturation. The method was validated by imaging different oils, using gas-liquid chromatography (GLC) as the reference. The degree of saturation agreed well with GLC, and feasibility of the method was demonstrated in the thigh of a volunteer. The developed methods have applications in clinical settings, and are already being used in several research projects, including studies of obesity, dietary intervention, and the metabolic syndrome.

This thesis consists of three articles investigating the asymptotic behaviour of cosmological spacetimes with symmetries arising in Mathematical General Relativity. In Paper A and B, we consider spacetimes with Bianchi symmetry and where the matter model is that of a perfect fluid. We investigate the behaviour of such spacetimes close to the initial singularity ('Big Bang'). In Paper A, we prove that the Strong Cosmic Censorship conjecture holds in non-exceptional Bianchi class B spacetimes. Using expansion-normalised variables, we further show detailed asymptotic estimates. In Paper B, we prove similar estimates in the case of stiff fluids. In Paper C, we consider T2-symmetric spacetimes satisfying the Einstein equations for a non-linear scalar field. To given initial data, we show global existence and uniqueness of solutions to the corresponding differential equations for all future times. In the special case of a constant potential, a setting which is equivalent to a linear scalar field on a background with a positive cosmological constant, we investigate in detail the asymptotic behaviour towards the future. We prove that the Cosmic No-Hair conjecture holds for solutions satisfying an additional a priori estimate, an estimate which we show to hold in T3-Gowdy symmetry. / Denna avhandling består av tre artiklar som undersöker det asymptotiska beteendet hos kosmologiska rumstider med symmetrier som uppstår i Matematisk Allmän Relativitetsteori. I Artikel A och B studerar vi rumstider med Bianchi symmetri och där materiemodellen är en ideal fluid. Vi undersöker beteendet av sådana rumstider nära ursprungssingulariteten ('Big Bang'). I Artikel A bevisar vi att den Starka Kosmiska Censur-förmodan håller för icke-exceptionella Bianchi klass B-rumstider. Med hjälp av expansions-normaliserade variabler visar vi detaljerade asymptotiska uppskattningar. I Artikel B visar vi liknande uppskattningar för stela fluider. I Artikel C betraktar vi T2-symmetriska rumstider som uppfyller Einsteins ekvationer för ett icke-linjärt skalärfält. För givna begynnelsedata visar vi global existens och entydighet av lösningar till motsvarande differentialekvationer för all framtid. I det speciella fallet med en konstant potential, en situation som motsvarar ett linjärt skalärfält på en bakgrund med en positiv kosmologisk konstant, undersöker vi i detalj det asymptotiska beteendet mot framtiden. Vi visar att den Kosmiska Inget-Hår-förmodan håller för lösningar som uppfyller en ytterligare a priori uppskattning, en uppskattning som vi visar gäller i T3-Gowdy-symmetri. / <p>QC 20171220</p>