The magnetic structures and spin reorientations of RGa (R = Gd, Dy, Ho and Er) intermetallic compounds have been investigated using neutron powder diffraction and rare earth Mössbauer spectroscopy. The aim has been to determine the magnetic structures of these compounds before and after their spin reorientation transitions and to understand the role of the crystal field and exchange interactions in the spin reorientation mechanism. The results have been compared with those found from previous single-crystal susceptibility measurements on RGa and the recent 119Sn Mössbauer spectroscopy work on Sn-doped RGa compounds. The magnetic structures obtained at low temperatures are a simple collinear ferromagnetic in DyGa, canted ferromagnetic in HoGa and a non-collinear ferromagnetic in GdGa. The spin reorientation in ErGa was also observed by 166Er Mössbauer spectroscopy. These results show that both the crystal field and exchange interactions play an important role in the reorientation mechanism.

The magnetic structures and spin reorientations of RGa (R = Gd, Dy, Ho and Er) intermetallic compounds have been investigated using neutron powder diffraction and rare earth Mössbauer spectroscopy. The aim has been to determine the magnetic structures of these compounds before and after their spin reorientation transitions and to understand the role of the crystal field and exchange interactions in the spin reorientation mechanism. The results have been compared with those found from previous single-crystal susceptibility measurements on RGa and the recent 119Sn Mössbauer spectroscopy work on Sn-doped RGa compounds. The magnetic structures obtained at low temperatures are a simple collinear ferromagnetic in DyGa, canted ferromagnetic in HoGa and a non-collinear ferromagnetic in GdGa. The spin reorientation in ErGa was also observed by 166Er Mössbauer spectroscopy. These results show that both the crystal field and exchange interactions play an important role in the reorientation mechanism.

L'élongation embryonnaire contrôle la transformation embryonnaire de C. elegans qui passe d'un embryon ovoïde à une larve vermiforme. C'est un modèle idéal pour la dissection de voies de signalisation qui contrôlent la morphogénèse des tissus et l'intégration de ces signaux dans les diverses couches cellulaires. L'élongation peut être divisée en deux parties : l'élongation précoce qui implique la contraction de l'hypoderme, alors que l'élongation tardive implique l'action synergique des muscles et de l'hypoderme. La contraction des filaments d'actines est régulée par le niveau de phosphorylation des chaînes légères de la myosine (mlc-4). Les GTPases Rho sont des protéines de signalisation régulées par l'action de 3 familles protéiques : les « GTPase-activating proteins » (GAPs), les « Guanine nucléotide exchange factors » (GEFs) et les « Guanine nucléotide dissociation inhibitors » (GDI). Les GTPases Rho contrôlent un large éventail de processus biologiques. Il y a trois GTPases Rho qui contrôlent l'élongation de C. elegans. Notre laboratoire a identifié une quatrième GTPase contrôlant l'élongation, CDC-42 et son régulateur, RGA-7. CDC-42 a été associée à la polymérisation de filaments d'actines dans les évènements de polarisation, de migration et de trafic membranaire (Harris KP. et Ulrich Tepass U., 2010). Nos résultats suggèrent que le gène rga-7 coderait pour trois formes protéiques résultant d'une initiation alternative de la transcription et que ces trois protéines seraient impliquées dans le contrôle de l'élongation. La délétion ok1498 induit un phénotype de létalité embryonnaire ayant une pénétrance variant entre 25 et 30%. Cette létalité est le résultat d'hypercontractions dorsales pendant l'élongation. L'activité catalytique du domaine GAP de rga-7 a révélé une affinité élevée pour la GTPases CDC-42 et faible pour les GTPases RHO-1 et MIG-2. Des analyses d'épistasies suggèrent que rga-7 contrôlerait l'activité de cdc-42 ainsi que de ses effecteurs wsp-1 et mrck-1 au cours de l'élongation. Nous émettons l'hypothèse que rga-7 pourrait contrôler la dynamique du recyclage des jonctions adhérentes (cadhérines) comme son orthologue humain probable PARG1, hypothèse que nous testerons lors d'études subséquentes. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : RGA-7, élongation, CDC-42, endocytose, GTPases, signalisation cellulaire, développement embryonnaire, filaments d'actine, jonctions adhérentes.

This work presents a modeling and control study of a reactive distillation column used for hydrogenation of benzene. A steady state and a dynamic model have been developed to investigate control structures for the column. The most important aspects of this control problem are that the purity of the product streams regarding benzene need to be met. At the same time as little toluene as possible should be converted. The former is a constraint imposed by EPA regulations while the latter is tied to process economics due to the high octane number of toluene. It is required to satisfy both of these objectives even under the influence of disturbances, as the feed composition changes on a regular basis. The dynamic model is used for developing transfer function models of two potential control structures. Pairing of inputs and outputs is performed based upon the Relative Gain Array (RGA) and PI controllers were designed for each control structure. The controller performance was then compared in simulation studies. From our results, control structure 2 performed better than control structure 1. The main advantage of CS2 over CS1 is noticed in the simulation of feed composition disturbance rejection, where CS2 returns all variables back to steady state within 3 hrs while it take CS1 more than 20 hrs to return the temperature variables back to steady state.

Master of Science / Department of Plant Pathology / John P. Fellers / Allan K. Fritz / Leaf rust is caused by Puccinia triticina and is one of the most widespread diseases of wheat worldwide. Breeding for resistance is one of the most effective methods of control. Lr16 is a leaf rust resistance gene that provides partial resistance at the seedling stage. One objective of this study was to use RNA-seq and in silico subtraction to develop new resistance gene analog (RGA) markers linked to Lr16. RNA was isolated from the susceptible wheat cultivar Thatcher (Tc) and the resistant Thatcher isolines TcLr10, TcLr16, and TcLr21. Using in silico subtraction, Tc isoline ESTs that did not align to the Tc reference were assembled into contigs and analyzed using BLAST. Primers were designed from 137 resistance gene analog sequences not found in Tc. A population of 260 F[subscript]2 lines derived from a cross between the rust-susceptible cultivar Chinese Spring (CS) and a Thatcher isoline containing Lr16 (TcLr16) was developed for mapping these markers. Two RGA markers XRGA266585 and XRGA22128 were identified that mapped 1.1 cM and 23.8 cM from Lr16, respectively. Three SSR markers Xwmc764, Xwmc661, and Xbarc35 mapped between these two RGA markers at distances of 4.1 cM, 10.7 cM, and 16.1 cM from Lr16, respectively. Another objective of this study was to use genotyping-by-sequencing (GBS) to develop single nucleotide polymorphism (SNP) markers closely linked to Lr16. DNA from 22 resistant and 22 susceptible F[subscript]2 plants from a cross between CS and TcLr16 was used for GBS analysis. A total of 39 Kompetitive Allele Specific PCR (KASP) markers were designed from SNPs identified using the UNEAK and Tassel pipelines. The KASP marker XSNP16_TP1456 mapped 0.7 cM proximal to Lr16 in a TcxTcLr16 population consisting of 129 F[subscript]2 plants. These results indicate that both techniques are viable methods to develop new molecular markers. RNA-seq and in silico subtraction were successfully used to develop two new RGA markers linked to Lr16, one of which was more closely linked than known SSR markers. GBS was also successfully used on an F[subscript]2 population to develop a KASP marker that is the most closely linked marker to Lr16 to date.

The purpose of this thesis is to investigate an alternative control strategy for a multi-variate non-linear process in a paper machine called the headbox. The proposed solution was intended to be able to be adopted on two different headbox types, currently controlled by different concepts. The methodology was to first create black-box models of the two different systems based on measurements, at one working point. Secondly, various control strategies were investigated. A more sophisticated multi-input multi-output controller MPC, or model predictive control, and a less sophisticated one, a single-input single-output, decentralised PI-controller. With help of simulations the performances of the both strategies were tested. Finally, only the decentralised control solution was implemented and evaluated through trial runs on a pilot machine. The main issue regarding the decentralised controller was the input-ouput pairing. Since the multi-variate system had four outputs and only three inputs, analysis had to be made in order to select three of those four, to form a square system. This analysis was based on the relative gain array (RGA). The resulting performance of the decentralised controller showed stability and adequate response times, surpassing the older system and making one component obsolete through the pairing changes. The MPC controller showed even better performance during simulations and shall also be taken into account if further investigatin is possible.

<p>The purpose of this thesis is to investigate an alternative control strategy for a multi-variate non-linear process in a paper machine called the headbox. The proposed solution was intended to be able to be adopted on two different headbox types, currently controlled by different concepts. </p><p>The methodology was to first create black-box models of the two different systems based on measurements, at one working point. Secondly, various control strategies were investigated. A more sophisticated multi-input multi-output controller MPC, or model predictive control, and a less sophisticated one, a single-input single-output, decentralised PI-controller. With help of simulations the performances of the both strategies were tested. Finally, only the decentralised control solution was implemented and evaluated through trial runs on a pilot machine. </p><p>The main issue regarding the decentralised controller was the input-ouput pairing. Since the multi-variate system had four outputs and only three inputs, analysis had to be made in order to select three of those four, to form a square system. This analysis was based on the relative gain array (RGA). </p><p>The resulting performance of the decentralised controller showed stability and adequate response times, surpassing the older system and making one component obsolete through the pairing changes. The MPC controller showed even better performance during simulations and shall also be taken into account if further investigatin is possible.</p>

Soybean has become one of the most important crops to the United States, resulting in a need to improve its disease resistance. The objectives of this study were to 1) design primers and develop PCR-based markers from disease-related expressed sequence tags (ESTs) and resistance gene analogues (RGAs), 2) assess the utility of such markers by diversity analysis of 12 soybean parental lines, and 3) search for possible association of the markers with known disease resistance genes by constructing a linkage map. The diversity analysis will allow this study to determine how well each marker can distinguish genotypes in soybean. Identifying the location of our markers in the soybean genome with the linkage map, will allow those related to disease resistance to be selected. A total of 202 simple sequence length polymorphism (SSLP) markers were constructed using a set of 1218 disease-related ESTs. Furthermore, 22 markers were constructed using previously identified RGA sequences. Both sets of markers were able to detect polymorphism in the diversity analysis. Also, 48 of the SSLPs, five of the RGAs, and 150 molecular markers were used to construct a soybean linkage map using 114 recombinant inbred lines (RILs). Several markers mapped to chromosomal regions known to contain disease resistance genes. This study has created a framework map, which will be useful for identifying the location of resistance genes, marker-assisted selection for resistance, discovering novel resistance genes, and understanding genome organization of resistance pathways in soybean. An effective approach to develop "candidate gene" markers has been demonstrated. / Master of Science

Long term supporting schemes for photovoltaic (PV) system installation have led to accommodating large numbers of PV systems within load pockets in distribution grids. High penetrations of PV systems can cause new technical challenges, such as voltage rise due to reverse power flow during light load and high PV generation conditions. Therefore, new strategies are required to address the associated challenges. Moreover, due to these changes in distribution grids, a different response behavior of the distribution grid on the transmission side can be expected. Hence, a new equivalent model of distribution grids with high penetration of PV systems is needed to be addressed for future power system studies. The thesis contributions lie in three parts. The first part of the thesis copes with the PV modelling. A non-proprietary PV model of a three-phase, single stage PV system is developed in PSCAD/EMTDC and PowerFactory. Three different reactive power regulation strategies are incorporated into the models and their behavior are investigated in both simulation platforms using a distribution system with PV systems. In the second part of the thesis, the voltage rise problem is remedied by use of reactive power. On the other hand, considering large numbers of PV systems in grids, unnecessary reactive power consumption by PV systems first increases total line losses, and second it may also jeopardize the stability of the network in the case of contingencies in conventional power plants, which supply reactive power. Thus, this thesis investigates and develops the novel schemes to reduce reactive power flows while still keeping voltage within designated limits via three different approaches: decentralized voltage control to the pre-defined set-points developing a coordinated active power dependent (APD) voltage regulation Q(P)using local signals developing a multi-objective coordinated droop-based voltage (DBV) regulation Q(V) using local signals   In the third part of the thesis, furthermore, a gray-box load modeling is used to develop a new static equivalent model of a complex distribution grid with large numbers of PV systems embedded with voltage support schemes. In the proposed model, variations of voltage at the connection point simulate variations of the model’s active and reactive power. This model can simply be integrated intoload-flow programs and replace the complex distribution grid, while still keepingthe overall accuracy high. The thesis results, in conclusion, demonstrate: i) using rms-based simulations in PowerFactory can provide us with quite similar results using the time domain instantaneous values in PSCAD platform; ii) decentralized voltage control to specific set-points through the PV systems in the distribution grid is fundamentally impossible dueto the high level voltage control interaction and directionality among the PV systems; iii) the proposed APD method can regulate the voltage under the steady-state voltagelimit and consume less total reactive power in contrast to the standard characteristicCosφ(P)proposed by German Grid Codes; iv) the proposed optimized DBV method can directly address voltage and successfully regulate it to the upper steady-state voltage limit by causing minimum reactive power consumption as well as line losses; v) it is beneficial to address PV systems as a separate entity in the equivalencing of distribution grids with high density of PV systems. / <p>The Doctoral Degrees issued upon completion of the programme are issued by Comillas Pontifical University, Delft University of Technology and KTH Royal Institute of Technology. The invested degrees are official in Spain, the Netherlands and Sweden, respectively. QC 20141028</p>

The strength of efficient metal-free catalysis will be examined in this thesis. Efforts towards more sustainable processes will be demonstrated through implementation of strategies that meet several of the 12 principles of Green Chemistry.In the first part, a stereoselective total synthesis of multiple alkaloids from the Corynantheine and Ipecac families together with their non-natural analogues will be disclosed. A highly efficient, common synthetic strategy is applied leading to high overall yields starting from easily available starting material. Overall operational simplicity and sustainability have been the main focus. Time-consuming and waste-generating isolations and purifications of intermediates have been minimized, as well as the introduction of protection-group chemistry. Moreover, the first example of the total synthesis of Hydroxydihydrocorynantheol together with its non-natural epimer has been accomplished in multi-gram scale without protection groups and without a single isolation or purification step in high overall yield and diastereoselectivity.In the second part, carbocations will be presented as highly effective and versatile non-metal Lewis acid catalysts. Lewis acidity-tuning of carbocations will be introduced and applied in several reactions to suppress competing reactions. Finally, the broad scope of carbocation catalyzed transformations will be exposed.At large, evident progress has been made towards more sustainable chemistry. / <p>QC 20140425</p>