<p>  </p> <p>Aromatic C-N bond formation is critical for synthetic chemistry in pharmaceutical, agrochemical, and natural product synthesis. Due to the prevalence of this bond class, many synthetic routes have been developed over time to meet the demand. The most recent and robust C-N bond formation reaction is the palladium catalyzed Buchwald-Hartwig amination. Considering the importance of the Buchwald-Hartwig amination, a high-throughput experimentation (HTE) campaign was devised to create a library in which chemists can refer to optimal reaction conditions and ligand/catalyst choice based on the nature of their substrates to be coupled. This study showed trends for the appropriate choice of ligand and catalyst, along with what bases, temperatures, stoichiometries, and solvents are appropriate for the selected substrate combination at hand. </p>

A functional central nervous system (CNS) is composed of numerous types of neurons. Neurons are derived from a limited number of multipotent neural stem cells. Previous studies have suggested three major strategies nature uses to diversify neurons: lineage identity specification that gives an individual neural stem cell distinct identity based on its position in the developing CNS; temporal identity specification that gives neurons derived from a neural stem cell distinct identities based on their birth-order within the lineage; and binary cell fate specification that gives different identities to the two sister postmitotic neurons derived from the terminal division of a common precursor. Through the combination of the three strategies, almost unlimited neuron types can be generated. To understand neuronal diversification, we have to understand the underlying molecular mechanisms of each of the three strategies. The fruit fly Drosophila melanogaster, has been an excellent model for studying neuronal diversity, mainly due to its easily traceable nervous system and an impressive collection of genetic tools. Studies in fly have provided us fundamental insights into lineage identity, temporal identity, and binary cell fate specifications. Nevertheless, previous studies mostly centered on the embryonic ventral nerve cord (VNC) because of its simpler organization. Our understanding of the generation of neuronal diversity in the fly brain is still rudimentary. In this thesis work, I focused on the mushroom body (MB) and three antennal lobe neuronal lineages, studying their neuronal diversification during postembryonic brain development. In Chapter I, I reviewed the previous studies that have built our current understanding of the neuronal diversification. In Chapter II, I showed that MB temporal identity changes are instructed by environmental cues. In Chapter III, to search for the potential factors that mediate the environmental control of the MB temporal identity changes, I silenced each of the 18 nuclear receptors (NRs) in the fly genome using RNA interference. Although I did not identify any NR important for the regulation of MB temporal identities, I found that unfulfilled is required for regulating axon guidance and for the MB neurons to acquire all major subtype-specific identities. In Chapter IV, I demonstrated that the Notch pathway and its antagonist Numb mediate binary cell fate determination in the three classical antennal lobe neuronal lineages— anterodorsal projection neuron (adPN), lateral antennal lobe (lAL), and ventral projection neuron (vPN)—in a context-dependent manner. Finally, in Chapter V, I did detailed lineage analysis for the lAL lineage, and identified four classes of local interneurons (LNs) with multiple subtypes innervating only the AL, and 44 types projection neurons (PNs) contributing to olfactory, gustatory, and auditory neural circuits. The PNs and LNs were generated simultaneously but with different tempos of temporal identity specification. I also showed that in the lAL lineage the Notch pathway not only specifies binary cell fates, but is also involved in the temporal identity specification.

Emerging evidence in both vertebrates and invertebrates is redefining glia as active and mobile players in synapse formation, maturation and function. However, the molecular mechanisms through which neurons and glia interact with each other to regulate these processes is not well known. My thesis work begins to understand how glia use secreted factors to modulate synaptic function. We use Drosophila melanogaster, a simple and genetically tractable model system, to understand the molecular mechanisms by which glia communicate with neurons at glutamatergic neuromuscular junctions (NMJs). We previously showed that a specific subtype of glia, subperineurial peripheral glia cells (SPGs), establish dynamic transient interactions with synaptic boutons of the NMJ and is required for synaptic growth. I identified a number of potential functional targets of the glial transcription factor, reverse polarity (repo) using ChIP-chip. I found that one novel target of Repo, Wg, is expressed in SPGs and is regulated by repo in vivo. Wnt/Wg signaling plays a pivotal role during synapse development and plasticity, including the coordinated development of the molecular architecture of the synapse. While previous studies demonstrated that Wg is secreted by motor neurons, herein I provide evidence that a significant amount of Wg at the NMJ is additionally provided by glia. I found that Wg derived from SPGs is required for proper GluR distribution and electrophysiological responses at the NMJ. In summary, my results show that Wg expression is regulated by Repo in SPGs and that glial-derived Wg, together with motor neuron-derived Wg, orchestrate different aspects of synapse development. My thesis work identifies synapse stabilization and/or assembly as a new role for SPGs and demonstrates that glial secreted factors such as Wg regulate synaptic function at the Drosophila NMJ.

The minimal element of the nervous system, the synapse, is a plastic structure that has the ability to change in response to various internal and external factors. This property of the synapse underlies complex behaviors such as learning and memory. However, the exact molecular and cellular mechanisms involved in this process are not fully understood. To understand the mechanisms that regulate synapse development and plasticity I took advantage of a powerful model system, the Drosophila larval neuromuscular junction (NMJ). In this system, both anterograde and retrograde signaling pathways critical for coordinated synapse development and plasticity have been documented. An anterograde WNT/Wingless (Wg) signaling pathway plays a crucial role in both developmental and activity-dependent synaptic plasticity at the NMJ. Presynaptic motor neuron terminals secrete highly hydrophobic Wg, which travels to relatively distant postsynaptic sites where it activates a signal transduction pathway required for postsynaptic development. In the first half of my thesis I unraveled a previously unrecognized cellular mechanism by which Wg is shuttled to postsynaptic sites. In this mechanism Wg rides on secreted microvesicles or exosomes that contain a dedicated WNT secretion factor, the WNT-binding transmembrane protein, Evenness Interrupted/Wntless/Sprinter (Evi/Wls/Srt). To our knowledge, this was the first in vivo study demonstrating that neurons release exosomes, which are involved in trans-synaptic communication. Moreover, this was the first study showing that hydrophobic WNT signals are transported to the extracellular space on exosomes to reach WNT-receptor containing target cells. Retrograde signals are also critical during development and plasticity of synaptic connections. These signals function to adjust the activity of presynaptic cells according to postsynaptic cell outputs, to maintain synaptic function within a dynamic range. However, the mechanisms that trigger the release of retrograde signals and the role of presynaptic cells in this signaling event are not clear. In the second half of my thesis, I provided evidence that a crucial component of retrograde signaling at the fly NMJ, Synaptotagmin-4 (Syt4), is transmitted to the postsynaptic cell through anterograde delivery of Syt4 via exosomes. Drosophila Syt4 is known to reside on postsynaptic vesicles at the NMJ and function as a calcium sensor to release a retrograde signal upon synaptic activity. This event is required for coordinated maturation of the presynaptic terminal. We demonstrated that retrograde Syt4 function in postsynaptic muscle is required for activity-dependent presynaptic growth. However, surprisingly, Syt4 protein was not synthesized in postsynaptic muscles. Instead, Syt4 was produced in motorneurons and transferred to postsynaptic muscle cells via exosome secretion by presynaptic cells. The above study provided evidence for a presynaptic control of postsynaptic retrograde signaling through exosomal transfer of an essential retrograde signaling component. In summary, this body of work reveals a novel mechanism of trans-synaptic communication through exosomes. While intercellular communication through exosomes had been demonstrated during antigen presentation in the immune system, our studies were the first to substantiate this mode of communication in the nervous system. Thus, these studies provide a significantly deeper and novel understanding of the mechanisms underlying synapse development and plasticity.

The formation of the anterior-posterior axis requires a symmetry-breaking event that starts gastrulation. Ultimately, the morphogenetic movements of gastrulation reshape the embryo to its final tri-dimensional form. In mouse embryos, the identity of the molecule that breaks the bilateral symmetry and sets in motion gastrulation remains elusive. The Wnt signaling pathway plays a pivotal role during axial specification and gastrulation in metazoans. Loss-of-function experiments have demonstrated a requirement of Wnt3 for gastrulation in mice. But because Wnt3 is expressed sequentially in two tissues, the visceral endoderm and the epiblast, its tissue specific requirements remain uncertain. Here, we report that embryos lacking Wnt3 specifically in the visceral endoderm do not form a primitive streak, mesoderm, endoderm or any derivatives. Visceral endoderm-specific Wnt3 mutants also lack primordial germ cells. Moreover, we provide data demonstrating that Wnt3 carries out its actions in the epiblast via the canonical Wnt pathway. Together, these data suggest that the posterior visceral endoderm via Wnt3, regulates the development of mouse embryos in a similar fashion to the amphibian Nieuwkoop center. Next, we conditionally ablated Wnt3 locus in the epiblast to investigate whether Wnt3 expression is also required in that tissue. Embryos lacking Wnt3 expression in the epiblast, but retaining its expression in the visceral endoderm, show delayed but not absent gastrulation. We conclude that the expression of Wnt3 in the epiblast is required for maintenance but not initiation of gastrulation in mouse embryos. Furthermore, we used in vitro and in vivo approaches to demonstrate that the Wnt3-mediated activation of the canonical Wnt pathway leads to β-catenin occupancy followed by transcription of key loci, including the Wnt3 locus itself, during gastrulation in mice. Our data indicate the presence of an autoregulatory loop in which Wnt3 controls its own expression and orchestrates the process of gastrulation in the mouse embryo.

Webbaserade kontrollerade experiment håller alltmer på att bli normen för mjukvaruföretagsom vill bli data-drivna. Ett av de vanligaste experimenten idag är A/Btester.Att få resultat från A/B-tester är enkelt, att få trovärdiga resultat är svårare.Även om forskningsområdet gällande A/B-testning är aktivt så finns det ännu ingenöverenskommen definition av nödvändiga förutsättningar för trovärdig A/B-testning.Denna uppsats presenterar en uppsättning förutsättningar och kopplar samman dessamed egenskaper för A/B-testningsplattformar. Resultaten visar vilka egenskaper enplattform ska inneha för att uppnå trovärdiga resultat. Uppsatsen presenterar ocksåen utvärdering av två vanliga A/B-testningsplattformar. Under denna utvärdering upptäcktesegenskaper som kan ha motsatt effekt på trovärdigheten av resultaten vilketockså diskuteras i uppsatsen. / Web-based controlled experiments are increasingly becoming the norm for softwaredevelopment companies who want to become data-driven. One of the most commonexperiments today is A/B-tests. While it is easy to get results from A/B-tests, gettingtrustworthy results is harder. Although the research field of A/B-testing is active,there is no agreed definition of the necessary conditions for running trustworthy A/Btest.This thesis presents a set of trustworthy conditions and connect these with A/Btestingplatform features. The results show what features to look for in platforms inorder to achieve trustworthy results. The thesis also presents an evaluation of twocommon A/B-testing platforms available today. During the platform evaluation otherfeatures were found that could have the opposite impact on the trustworthiness of theresults and this is also discussed in this thesis.

Les systèmes à grande échelle comme les Grilles ou les Nuages (Clouds) mettent à disposition pour les utilisateurs des ressources informatiques hétérogènes. Dans les Nuages, les accès aux ressources sont orchestrés par des contrats permettant de définir un niveau de qualité de service (temps de réponse, disponibilité ...) que le fournisseur doit respecter. Ma thèse a donc contribué à concevoir de nouveaux algorithmes distribués de verrouillage de ressources dans les systèmes large échelle en prenant en compte des notions de qualité de service. Dans un premier temps, mes travaux de thèse se portent sur des algorithmes distribués de verrouillage ayant des contraintes en termes de priorités et de temps. Deux algorithmes d'exclusion mutuelle ont été proposés : un algorithme prenant en compte les priorités des clients et un autre pour des requêtes avec des dates d'échéance. Dans un second temps, j'ai abordé le problème de l'exclusion mutuelle généralisée pour allouer de manière exclusive plusieurs types de ressources hétérogènes. J'ai proposé un nouvel algorithme qui réduit les coûts de synchronisation en limitant la communication entre processus non conflictuels. Tous ces algorithmes ont été implémentés et évalués sur la plateforme nationale Grid 5000. Les évaluations ont montré que nos algorithmes satisfaisaient bien les contraintes applicatives tout en améliorant de manière significative les performances en termes de taux d'utilisation et de temps de réponse. / Distributed large-scale systems such as Grids or Clouds provide large amounts of heterogeneous computing resources. Clouds manage ressource access by contracts that allow to define a quality of service (response time, availability, ...) that the provider has to respect. My thesis focuses on designing new distributed locking algorithms for large scale systems that integrate notions of quality of service. At first, my thesis targets distributed locking algorithms with constraints in terms of priorities and response time. Two mutual exclusion algorithms are proposed: a first algorithm takes into account client-defined priorities and a second one associates requests with deadlines. I then move on to a generalized mutual exclusion problem in order to allocate several types of heterogeneous resources in a exclusive way. I propose a new algorithm that reduces the cost of synchronization by limiting communication between non-conflicting processes.All algorithms have been implemented and evaluated over the national platform Grid 5000. Evaluations show that our algorithms satisfy applicative constraints while improving performance significatively in terms of resources use rate and response time.

Cette recherche interroge la notion d’expérimentation des innovations techniques en architecture. Elle vise à en expliciter les modalités, les enjeux et les limites pour le métier d’architecte et pour la théorie de l’architecture. Elle montre que l’architecture n’est pas un domaine d’application des techniques de construction, pensées comme des moyens instrumentaux élaborés en amont, mais qu’elle est un milieu d’expérimentation des techniques, essentiel à leur développement et à leur adaptation en situation complexe. L’architecture est aussi un champ de réflexions critiques sur nos manières d’agir et de construire, dans lequel la technique est en projet.Le terrain de recherche est celui de l’architecture de bois en France depuis son renouveau industriel dans la seconde moitié du XXe jusqu’à aujourd’hui. Il condense sur une période relativement courte les expérimentations constructives d’un matériau d’abord perçu comme archaïque après-guerre, puis élevé au rang de matériau moderne à partir des années 1960 et enfin reconnu comme le matériau phare de la construction écologique. Il offre la possibilité d’observer le passage de l’artisanat à l’industrie, l’évolution des méthodes et outils de production manuels, mécaniques puis numériques et leurs influences sur l’architecture. Il offre en même temps l’occasion d’étudier, à partir d’une unique matière première, l’état d’acceptabilité culturelle de nos technologies industrielles, selon que l’architecture met en avant le bois en tant que matériau moderne et transformé, ou en tant que matériau brut et naturel, entre fascination pour le progrès technique et critique de la société industrielle.Le format choisi est celui d’une thèse sur articles régulièrement publiés durant la recherche. Chacun des sept articles constitue l’étude de cas d’une situation d’innovation particulière dans la période considérée, en croisant les analyses architecturales et constructives. L’ensemble converge pour établir un relevé des différentes formes de l’expérimentation des innovations techniques en architecture et met en évidence certaines régularités de la démarche expérimentale dont la principale est le transfert d’innovation.Cette recherche tente de rendre explicite ce processus d’expérimentation créatif et réflexif, qui dispose de ses propres modalités, outils, temporalités, modes d’évaluation et de capitalisation de connaissances, distincts des canons de l’expérimentation scientifique. Les connaissances que cette thèse élabore invitent à renouveler l’enseignement des techniques dans les écoles d’architecture, en renouant leurs liens avec la création architecturale. / This research questions the notion of experimentation in technical innovations in architecture. It aims at elucidating the methods, stakes, and limits concerning both the profession of architect and the theory of architecture. It suggests that architecture is not a domain where construction techniques, seen as instrumental means resulting from an upstream work, are put in application, but a field of experimentation for these techniques, an essential step in their development and adjustment in more complex situations. Architecture is also an area of critical reflections on our ways of behaving and building, for which techniques are in planning.The field of research is that of timber architecture in France, from its industrial resurgence in the second half of the 20th century to the present. This field condenses, in a relatively short period of time, the building experimentations with a material that was first considered archaic after the war, then raised to the status of a modern material from the 1960s, to be acknowledged as the leading material for ecological construction. It allows us to examine the transition from arts and crafts to industry, the evolution of the methods, of the tools of production, from hand-operated to mechanical to digital, and their influence on architecture. Simultaneously, it enables us to delve into, based on a single raw material, the attitude of cultural acceptance from our industrial technologies – depending on whether architecture showcases timber as a modern and processed material or as a raw and natural resource – between the fascination for technical progress and a criticism of the industrial society.The chosen format is that of a thesis based on regularly published articles during the research phase. Each of the seven articles consists of a case study on a specific innovation during the selected time period, cross-referencing architectural and building analyses. The composition as a whole converges to establish a survey of the different forms taken by technical innovations in architecture and highlights some consistencies in the experimental process, the main consistency being the transfer of innovation.This research seeks to clarify this process of creative and rational experimentation which has its own methods, tools, temporalities, modes of evaluation and of capitalization of knowledge, distinct from the canons of scientific experimentation. The findings of this thesis prompt a new approach to teaching techniques in architecture schools, through reviving their links with architectural creation.

An investigation was done on the methods used by performers of classical flute music to improve their flute tone. A literature study was done and a methodology created. This resulted in detailed dissection and then discussion of the various aspects that influence flute tone. Thereafter a series of practice charts were developed, which can be used to guide performers, students and teachers in their experiment to improve and diversify flute tone. The key areas of flute tone that were examined are: embouchure, lip flexibility, vibrato and tone colour. It has been found that different methods work for different people to improve their flute tone, and therefore personal experimentation is necessary in order to achieve the required tone, which also depends on personal taste. / Dissertation (MMus (Performing Art))--University of Pretoria, 2006. / Music / MMus / unrestricted

La trascendencia de la música en el Perú va más allá del carácter estético que pueda adoptar por cada región en la que se genera. Su importancia recae en la capacidad de establecerse como un generador de identidad nacional y promotor industrial. En este contexto la experimentación musical y la difusión son dos aspectos que deben ser atendidos, comprendiendo la problemática actual de la industria musical en nuestro país. El Centro de Experimentación y Difusión de Música Contemporánea propone un emplazamiento estratégico para el desarrollo musical con importante riqueza paisajística dada su ubicación frente a un gran parque como es el “Campo de Marte” en el distrito de Jesús María en la ciudad de Lima, entorno que aporta favorablemente al desempeño de las actividades del usuario. Así también su relación directa con el Centro Cultural Sérvulo Gutiérrez enriquece el programa del proyecto. El proyecto por su parte dota de servicios al parque y a la comunidad. La investigación contempla marco teórico, proyectos referenciales, usuario, estudio del lugar, parámetros de diseño y programa arquitectónico; proponiendo así una solución programática y arquitectónica que pone en valor el producto artístico-cultural nacional, a sus autores, ejecutantes y promotores, atendiendo a su vez los requerimientos de una industria que potencia la identidad nacional y que contribuye con el desarrollo económico del país. / The transcendence of Music in Peru goes beyond the aesthetic value provided by its regional origin. Its importance relies in its capacity to serve as a conduit for national identity and a generator of economic growth. In this context, experimentation and diffusion of music are two aspects that must be broached with special attention given the intricate reality of the music industry in our country. The “Contemporary Music Center for Experimentation and Broadcasting” is a strategically located venue for the development and appreciation of music which offers rich landscapes and amenities as it is located across from “El Campo de Marte” and “Centro Cultural Sérvulo Gutiérrez” in the city of Jesus María, Lima. Hence, this architectural project provides both the community and the national reserve park with services. The investigation includes theoretical framework, referential projects, user, site analysis, design parameters and an architectural brief to present a well-substantiated programmatic and architectural initiative which goal is to enhance the artistic and cultural experience for the community. / Tesis