Les alphabets structuraux sont des collections de motifs structuraux répétés dans les structures de protéines. Durant ma thèse, j'ai utilisé l'un d'eux, les blocs protéiques (BPs), pour diverses applications comme la prédiction, la comparaison et l'analyse de structures de protéines. J'ai d'abord étudié les variations structurales observées au sein de structures ayant des séquences protéiques identiques et au cours de simulations de dynamique moléculaire. Les résultats de ces analyses ont été synthétisés sous la forme de matrices de substitution et ont montré des similitudes surprenantes avec les précédentes matrices établies pour les protéines homologues ou les ensembles RMN. La méthode kPRED qui permet de prédire le squelette des protéines sous forme de BPs a été amélioré en prenant en compte les structures locales voisines. La nouvelle version privilégie aussi les informations provenant des protéines homologues lorsqu'elles sont disponibles, atteignant une précision moyenne de 66,3% sur un jeu de données test. J'ai aussi étendu la portée de la base de données PENTAdb pour couvrir l'ensemble des structures de la PDB. Je montre que l'effet de cette augmentation de 950% dans le contenu de PENTAdb améliore notre compréhension de la relation séquence-structure au niveau d'un pentapeptide. J'ai également utilisé PB-ALIGN, un outil de comparaison rapide et efficace de structures des protéines, pour comparer toutes les structures protéiques dans la PDB entre elles et pour étudier les similitudes structurales. J'ai généré une grande collection de données d'alignement et j'explore son usage pour l'annotation fonctionnelle et l'identification de possibles relations évolutives. / Structural motifs found in protein structures. They help in approximating protein structure as a 1D string with minimal loss of structural information. Here I have employed a widely used structural alphabet called Protein Blocks (PB) for various applications like predicting, comparing and analyzing protein structures. PBs were used to study the structural variations in proteins with identical primary structure and also during the course of molecular dynamics (MD) simulations. The results from these analyses were summarized in the form of substitution matrices and showed striking similarities to previously established matrices for homologous proteins and NMR ensembles. I improved kPRED, a knowledge-based prediction of protein backbone in terms of PBs, by taking into consideration the neighboring local structures. The new version of the algorithm also privileges structural information from homologous proteins when available reaching an average accuracy of 66.3% on a benchmark dataset. The scope of the PENTAdb database has been expanded to cover the entire protein structure space in an automated manner. I show that the effect of this 950% increase in the contents of PENTAdb improves our understanding of the sequence-structure relationship at the pentapeptide level. I also used PB-ALIGN, a fast and efficient protein structure comparison tool, to compare all protein structures in PDB in an all-vs-all manner and to investigate PB-based structural similarities. This generated a huge collection of alignment data and I discuss its use for functional annotation and identification of possible evolutionary relationships.

L'analyse et la compréhension des mécanismes d'érosion en présence d'un environnement critique au niveau de pression et de température des produits de combustion d'un propergol solide au sein d'une tuyère de moteur fusée, constituent l'objectif principal de ce présent mémoire. Les principaux paramètres, le pourcentage d'aluminium dans l'écoulement, la température adiabatique de flamme.le flux de chaleur en face de la géométrie de l' insert et ses propriétés thermochimiques, sont plus particulièrement étudiés à travers une approche numérique et expérimentale. Le phénomène d'ablation qui se produit au niveau de l' insert d'une tuyère pendant le fonctionnement du moteur propergol solide est ainsi étudié et des résultats d'essais des moteurs à échelle réduite et pleine sont présentés puis simulés numériquement. En effet, les essais mis en place, riches en résultats sur les conditions du matériau de l'insert avant et après le tir, ne permettent pas une analyse complète du développement des mécanismes en jeu au cours du temps de fonctionnement des moteurs. Pour introduire ces phénomènes physiques plutôt complexes, une stratégie de développement progressive est mise en place. Au départ, un modèle 1D a traité les équations de transfert de chaleur utilisant une technique de discrétisation numérique multi-blocs. A partir de la méthode 1D, des expressions simples pour représenter l'évolution des fronts d'ablation et de pyrolyse sont définies.Ces expressions sont alors utilisées de façon directe sur le traitement des problèmes axisymétriques et confrontées avec les simulations du moteur test. Finalement, la méthode aux frontières immergées est appliquée pour traiter du couplage entre l'écoulement et l'insert, mettant en évidence le phénomène d'ablation. Les simulations numériques reproduisent les résultats expérimentaux et montrent une méthodologie numérique robuste, correspondant à des attentes en ce qui concerne l'évaluation du phénomène d'ablation au sein d'une tuyère de moteur fusée. / The main objective of this study is understand the ablation mechanisms in the presence of a critical environment in pressure and temperature within a solid propellant rocket motor. The well-known parameters, aluminum percentage in the flow, adiabatic flame temperature and the consequent heat flux in front of the geometry of the insert and its thermochemical properties are studied from anumerical and experimental strategy. The ablation phenomenon, which occurs at the nozzle insert during the operation of the solid propellant rocket motor, is th us studied and results of tests of the small and full-scale motors are presented as well as numerically simulated. Indeed, tests carried-out provide results on the conditions of the material of the insert before and after firing tests, do not allow is to provide a complete analysis of the development of the mechanisms involved during the running time of the engines. To introduce these rather complex physical phenomena a strategy of progressive development is followed. Initially, a 1D model treated the heat transfer equations using a multi-block numerical discretization technique. From the 1D method, simple expressions to represent the evolution of the ablation and pyrolysis fronts are defined. These expressions are then used directly on the treatment of axisymmetric problems and confronted with simulations of the scale motor. Finally, the immersed boundary method is applied to tackle coupling between flow and heat transfer on the insert, highlighting the phenomenon of ablation. The numerical simulations reproduce the experimental results and show a robust numerical methodology, corresponding to expectations in what concerns the evaluation of the ablation phenomenon within a solid propellant rocket motor nozzle.

Magister Legum - LLM / The principal objective of this research was a critical examination of the Generalised System of Preference schemes as a form of special and differential treatment under the Enabling Clause with specific reference to the complaint brought against the European Union (EU) by India regarding the EU's granting of tariff preferences to developing countries with illegal drug trafficking problem. / South Africa

Regional integration can refer to the trade unification between different states by partial or full abolition of customs tariffs on trade taking place within the borders of each state. This is meant in turn to lead to lower prices for distributors and consumers (as no customs duties are paid within the integrated area) and the goal is to increase trade. (Economic integration,1950, p66) According to Mattli (1999, p.42), the analysis of the first problem takes the decision to adopt an integration treaty as a given, and is primarily concerned with identifying the condition under which the process of integration is likely to succeed or to fail. Implementation of an agreement by heads of states to tie the economies of their countries closer together entails a lengthy process of establishing common roles, regulations, and policies that are either based on specific treaty provisions or derived from general principles and objectives written into the integration agreement. Regional integration can be applied for varying forms of economic co-ordination or co-operation amongst different neighbouring states, there will however always be different political agendas in the process. If there is a treaty amongst member states, this treaty has to be enforced or it may result in the development of differences. “In order to address national priorities through regional action most member states had been allocated the responsibility of co-ordinating one or more sectors. This involved proposing sector policies, strategies and priorities, and processing projects for inclusion in the sectoral programme, monitoring progress and reporting to the council of Ministers”. (Department of International Relations & Co-operation, Republic of South Africa). Richard Baldwin, Daniel Cohen, Andre Sapir and Anthony Venables argue that, using the same basic model as Bond and Sypropoulos (1996a), they consider trigger strategies such that initially there is inter-bloc free trade supported by the threat of perpetual trade war if any party breaks the agreement. Regional integration can be understood as the process of providing common rules, regulation, and policies for a region. Regional integration is defined as a process that allows member states to have access to each other’s markets on a voluntary basis and at various degrees. Economic, political, social and cultural benefits are realised from this interaction. (Lee MC, 1999, p30) Regional integration can be seen as co-operation in a broader context but can also be an important framework, through programmes within each regional bloc. According to (Keet ,2005,p22) since the birth of democratic South Africa, regional co-operation is also seen – in addition to the broader African aims-to be an important framework, through programmes within the Southern African Development Community (SADC), within which to address the gross imbalances created both within and between the economies of the region. Regional integration has become a way of assisting the emerging economies to be able to use their proximity to align their economies with the core for economic development. According to (Hamdok, 1998, p34) the effective implementation of regional integration is founded on an enabling environment that promotes accountability, transparency and respect for the rule of law. Also a strong institutional framework at the regional and national levels is fundamental to streamline regional agreements into national policies. In addition, the establishment of effective transnational implementation tools provide opportunities to push reforms conducive to good governance at the regional level. A clear demonstration of this can be observed in effective? legal systems and the need for a regional framework and related judicial institutions to provide an improved regional environment for private development. Integration always provides space for member states to assist in the development of other member states and which have a common economic approach to development. This is done in order to ensure that there are incentives for all member states as compared to those who are outside the bloc. As evidenced in the case of Europe, economic integration helps create a homogenous space and, to some extent, equalises living conditions and if all other regional blocs follow this process the benefit becomes greater. These appear to be prerequisites for a dialogue on the harmonisation of political stands. Indeed, an economic space that is physically integrated; where goods and services move speedily and smoothly; where, besides, the mobility of factors (manpower, capital, energy and inputs) are not subjected to hindrances; where, finally, microeconomic policies are harmonised, is likely to offer equal opportunities to all. Such a high degree of economic integration is not sustainable without a policy dialogue on issues that, at first, may not fall squarely under the rubrics of economic field; peace and security, defense, diplomacy etc. (Blayo N, 1998, P.5) The process of regional co-operation within the Southern African Development Community (SADC) started in in 1980 through the formation of the Co-ordinating Conference which was later changed to SADC IN 1992. Even though it is clear that the South African government played a dominant role because of its apartheid policies, the basic condition was to start the process of integration and open the process of economic co-operation within the region. The Governments of the Republic of South Africa, the Republic of Botswana, the Kingdom of Lesotho and the Kingdom of Swaziland- being desirous of maintaining the free interchange of goods between their countries and of applying the same tariffs and trade regulations to goods imported from outside the common customs area as hereinafter defined; “Recognising that the Customs Agreement on 29 June 1910 as amended from time to time , requires modification to provide for the continuance of the customs union arrangements in the changed circumstances on a basis designed to ensure the continued economic development of the customs union area as a whole, and to ensure in particular that these arrangements encourage the development of the less advanced members of the customs union and the diversification of their economies, and afford to all parties equitable benefits arising from trade among themselves and other countries”.(Government Notice, R 3914,p1). Even though there’s an acknowledgement that under the difficult conditions during apartheid, there was a need for the region to develop a common approach towards development and sustainable growth in the Southern African region. All countries in the region had to co-operate for long term sustainable economic growth, peace and security. “In 1980, the Southern African Development Co-ordination Conference (SADCC) was established with the major objectives of decreasing economic dependence on the apartheid regime and fostering regional development. The strategy adopted for meeting these objectives was regional development and co-operation. In 1992 SADCC was reborn, as the Southern African Development Community (SADC). The member states decided the time had come to move the region towards the creation of one regional market”. (Lee MC, 1999, p1) “Through the establishment of the Southern African Customs Union (SACU) the Southern African region has managed under difficult conditions of economic inequalities to standardise the trade links amongst member states, although there is still more to be done in the region to achieve shared goals of development. The Southern African Customs Union (SACU) links the trade, regimes of Botswana, Lesotho, Namibia, South Africa and Swaziland.

No description available.

Cette these presente quelques aspects de la theorie des blocs generalises pour les groupes finis. Apres une breve description des theories classique et generalisee, on y etudie les proprietes des blocs generalises de certains groupes. On montre l'existence d'isometries parfaites generalisees dans trois familles de groupes de Lie de rang 1, generalisant ainsi une conjecture de M. Broue. On etudie ensuite le concept de groupe de Cartan generalise, et une formule est donnee pour l'ordre dans le groupe de Cartan des caracteres du groupe symetrique. Enfin, on definit des blocs generalises dans les groupes lineaires finis, et on montre que certaines unions de blocs de caracteres unipotents satisfont un analogue de la Conjecture de Nakayama ainsi qu'un analogue du Deuxieme Theoreme de Brauer.

Thesis (Ph. D.)--Vanderbilt University, 1997. / Includes bibliographical references (leaves 115-120).

Thesis (Ph. D.)--State University of New York at Binghamton, Dept. of Economics, 2005. / Includes bibliographical references.

Ces travaux ont pour objet la synthèse et la caractérisation de nouveaux électrolytes polymères pour batterie lithium métal polymère (LMP). L’objectif principal de ces électrolytes est de combiner une conductivité ionique élevée jusqu’à basse température et une résistance efficace contre les dendrites de lithium. Pour y parvenir, trois catégories de copolymères à bloc ont été élaborés, ils permettent d’obtenir une synergie de propriétés à priori antagonistes au sein d’un même matériau. Premièrement, la rigidité du polystyrène (PS) a été combinée à la conductivité du polyoxyéthylène (POE) dopé avec un sel de lithium (LiTFSI). Le POE a été préalablement modifié pour en abaisser la température de fusion (Tf) initialement située à 60°C, ce qui permet d’atteindre de hautes conductivités (7.10-5 S.cm-1) à 40°C, associées à un module d’Young de 0,3 MPa. Cependant, les bonnes conductivités de ces matériaux ne sont assurées que par une petite fraction de Li+ (t+=0,15). Cela crée des gradients de concentration qui limitent les performances des batteries. Pour pallier cela, l’anion TFSI a été greffé sur le bloc PS (PSTFSI), augmentant le t+ à 1. Le bloc PSTFSI combiné à du POE modifié a permis des conductivités remarquables pour un électrolytes solide (10-6 S.cm-1 @ 40°C). Dans un second temps, l’ajout d’une chaine perfluorée entre le PS et l’anion a permis un gain supplémentaire de conductivité par rapport au PSTFSI (2.10-5 S.cm-1 @ 60°C), uniquement assurée par les Li+. Dans chacune des trois catégories d’électrolytes plusieurs compositions ont été synthétisées, nous permettant de suivre l’impact de cette composition sur les morphologies, les propriétés thermodynamique et mécanique ainsi que sur les propriétés de transport. Finalement, des batteries LMP de laboratoire ont été assemblées avec les meilleurs électrolytes. / This work deals with synthesis and characterization of new polymer electrolytes for lithium metal polymer (LMP) batteries. The main challenge of polymer electrolytes is to combine both high ionic conductivity at low temperature and good mechanical properties. To overcome these issues, block copolymers have been designed. Remarkable properties are reached thanks to the self-assembly of these triblock copolymers. Mechanical properties are given by stiff polystyrene (PS) domains whereas ionic mobility operates in an ionophilic phase, polyoxyethylene (POE) with a lithium salt (LiTFSI). By introducing chemical defects in the POE backbone, melting temperature of the copolymer has been considerably lowered leading to conductivities of about 7.10-5 S.cm-1 and a Young’s modulus of 0.3 MPa at 40°C. If interesting properties are obtained thanks to this strategy, the small fraction of conductivity insured by lithium ions (t+=0.15) remains an issue. The low t+ leads to large concentration gradients limiting the performances of the system. In a second approach, TFSI anions have been covalently tethered on the PS backbone, raising the t+ to 1. An important increase of Li+ conductivity was obtained by adding a perfluorinated spacer between PS and TFSI moieties, with an ionophilic phase based on PEO (2.10-5 S.cm-1 @ 60°C). The chemical modification of the PEO block leads to Li+ conductivities of 10-6 S.cm-1 at 40°C. The composition of these different copolymers have been varied and their structural, thermal, mechanical and transport properties have been studied. Finally the best electrolytes of each category have been assessed in a full cell configuration.

Diss.--Universität Hamburg, 2004. / Bibliography: p. 295-328.