In recent years, the emergence and development of crowd-sourced geospatial data has provided challenges and opportunities to national mapping agencies as well as commercial mapping organisations. Crowd-sourced data involves non-specialists in data collection, sharing and maintenance. Compared to authoritative geospatial data, which is collected by surveyors or other geodata professionals, crowd-sourced data is less accurate and less structured, but often provides richer user-based information and reflects real world changes more quickly at a much lower cost. In order to maximize the synergistic use of authoritative and crowd-sourced geospatial data, this research investigates the problem of how to establish and validate correspondences (matches) between spatial features from disparate geospatial datasets. To reason about and validate matches between spatial features, a series of new qualitative spatial logics was developed. Their soundness, completeness, decidability and complexity theorems were proved for models based on a metric space. A software tool `MatchMaps' was developed, which generates matches using location and lexical information, and verifies consistency of matches using reasoning in description logic and qualitative spatial logic. MatchMaps was evaluated by the author and experts from Ordnance Survey, the national mapping agency of Great Britain. In experiments, it achieved high precision and recall, as well as reduced human effort. The methodology developed and implemented in MatchMaps has a wider application than matching authoritative and crowd-sourced data and could be applied wherever it is necessary to match two geospatial datasets of vector data.

The provision of free basic water for domestic uses and a more equal distribution of water for productive uses are seen as important instruments to redress inequities from the past and eradicate poverty in South Africa (SA). Although the government committed itself to providing free basic water for all, this result is still far to be reached, particularly in rural areas. Financing of multiple use water services was identified as an important ingredient to insure improved access to water for rural poor in SA and at the same time allow productive uses and broaden livelihood options. Recent evidence indicated the potential contribution that productive uses of domestic water might make to food security and poverty reduction in rural areas of SA. Following the principles of integrated water resource management (IWRM), efficient, equitable and sustainable investment in improved water services should be demand driven, that is, it should be based on a thorough understanding of effective demand by consumers for multiple use water services. The assessment of demand for improved water services provides the basis for micro level analysis of consumer benefits from multiple water uses. Such studies are not common in SA’s rural areas, where most of the economic analyses focus on either domestic or irrigation water demand. This study attempts to fill this gap by assessing the household demand for multiple use water services in Sekororo-Letsoalo area in the Limpopo Province. Choice modelling is the approach used to identify the attributes determining demand for water services and quantify their respective importance. Households are presented with alternative sets of water services, corresponding to different levels of the attributes. In this study, the following attributes were used: water quantity, water quality, frequency of water supply, price of water, productive uses of water, and source of water. Choice modelling allows estimating the relative importance of these attributes for various strata of the studied population, and ultimately provides a measure of the willingness to pay for different aspects of water demand (attributes), including productive water uses. Results show that households in rural areas are willing to pay for water services improvements. Due to the poor quality of present water services in the area, users are primarily concerned with basic domestic uses and demand for non domestic water uses is low. Only households already relatively well served are interested in engaging in multiple water uses. / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Agricultural Economics, Extension and Rural Development / unrestricted

Las giberelinas (GAs) son hormonas vegetales que regulan diversos procesos del desarrollo vegetativo y reproductivo de las plantas. Los niveles de GAs activas están regulados principalmente por enzimas de biosíntesis como las GA 20-oxidasas (GA20ox) y GA 3- oxidasas (GA3ox) y por enzimas de catabolismo como las GA 2-oxidasas (GA2oxs). En tomate (Solanum lycopersicum L.) las GA2oxs están codificadas por una familia multigénica de 5 miembros, SlGA2ox. El objetivo principal de nuestro trabajo es estudiar el papel de los genes SlGA2ox en el desarrollo de tomate. Para determinar como están regulados estos genes estudiamos su patrón de expresión en tejidos vegetativos y reproductivos de tomate y en respuesta a variaciones en los niveles endógenos de GAs. Se observó que los genes SlGA2ox tienen un alto grado de redundancia y que, en plántulas, no son inducibles por GAs. Los genes con mayores niveles de expresión en los tejidos vegetativos resultaron ser los genes SlGA2ox3, - 4 y -5 mientras que los genes SlGA2ox1 y SlGA2ox2 parecen ser importantes en el control del crecimiento del ovario ya que están reprimidos en ovarios polinizados en crecimiento y se inducen en ovarios no fertilizados. Para estudiar la función de estos genes en el desarrollo de la planta se empleó un abordaje de genética reversa usando silenciamiento génico post-transcripcional múltiple y simple. Para el silenciamiento múltiple se usó una construcción de tipo horquilla con una secuencia quimérica homóloga a los cinco genes (shRNA2ox) y para el silenciamiento del gen SlGA2ox1 se usó una construcción de tipo micro-RNA artificial (amiRNA2ox1). Ambas construcciones indujeron el silenciamiento, siendo éste más eficiente cuánto más abundante es el mensajero diana. El silenciamiento múltiple inducido por la construcción 35S::shRNA2ox provocó un incremento significativo de los niveles de la giberelina activa GA4 en ovarios. Además, los ovarios no fertilizados crecían mucho más en las plantas transgénicas que en las plantas silvestres (al menos 30 veces más) y presentaban cierto grado de capacidad partenocárpica que no poseían las plantas silvestres, desarrollando entre un 5 y un 37% de frutos partenocárpicos. Los ovarios polinizados de las plantas transgénicas se desarrollaban algo más rápido inicialmente, pero producían frutos del mismo tamaño a los silvestres. Estos resultados sugieren que el papel de las GAs en el crecimiento del fruto de tomate puede estar mediado, al menos en parte, por las GA 2-oxidasas. En el desarrollo vegetativo de estas plantas no se detectaron los efectos fenotípicos clásicos de la superproducción de GAs, ni se detectó ningún incremento en los niveles de GAs en tallos ni en ápices. Sin embargo se observó una inhibición significativa de la ramificación lateral que parecía deberse a un mayor contenido de GA4 detectado en las yemas axilares. Este fenotipo, no esperado, era suprimido eficientemente cuando se inhibía la síntesis de GAs mediante la aplicación del inhibidor paclobutrazol. Estos resultados sugieren un papel para las GAs como represores de la ramificación y que las GA 2-oxidasas son importantes en el control de la aparición de ramas laterales mediado por GAs. En las plantas 35S::amiRNA2ox1, donde solo se silenció el gen SlGA2ox1, a diferencia de lo que ocurre en las plantas de silenciamiento múltiple, no se detectaron cambios en los niveles de GAs activas, ni alteraciones en la ramificación, ni se mostraron efectos reproducibles sobre la partenocarpia. De estos resultados se deduce que el silenciamiento del gen SlGA2ox1 no es suficiente para inducir cambios significativos en el fenotipo de las plantas de tomate probablemente debido a la redundancia génica. En resumen, las GA 2-oxidasas parecen tener un papel en la regulación de los niveles de GAs en los ovarios y en las yemas axilares de tomate y su silenciamiento génico puede inducir crecimiento partenocárpico de los ovarios e inhibición de la ramificación. / Martínez Bello, L. (2014). Estudio del papel de los enzimas de catabolismo GA 2-oxidasas en el desarrollo de tomate (solanum lycopersicum L.) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/37884 / TESIS

The thesis is focused on the study of properties of GaN nanocrystals and Ga structures on the surface of silicon and graphene substrate. In the theoretical part of this thesis, the basic properties of Ga/GaN and graphene are described, as well as their applications or connection of both structures together in different devices. The ability of metal nanoparticles to enhance not only photoluminescence, due to the interaction of the material with surface plasmons, is also shown in several examples. The experimental part of the work first deals with the production and characterization of graphene sheets prepared by Chemical Vapor Deposition. Ga/GaN growth on both types of substrates was performed in a UHV chamber using an effusion cell for Ga deposition and an atomic ion source for nitridation. Prepared structures were characterized using various methods (XPS, SEM, AFM, Raman spectroscopy or photoluminescence). In the last step, GaN nanocrystals were coated with Ga islands to study the photoluminescence enhancement.

This thesis deals with deposition of GaN thin films and GaN selective growth utilizing pyrolyzed resist masks. Carbon masks were prepared on silicon substrates by electron-beam litography and resist pyrolysis. As a further step, Ga and GaN were deposited on the masked substrates by Moleculer Beam Epitaxy (MBE) method. A selective growth of Ga droplets was achieved. These results were used for preparation of GaN crystallites by pulse deposition. It is also shown that direct MBE deposition of GaN on the masked substrates leads to a selective growth of GaN thin films with GaN film growing only on the areas which are not covered by the carbon mask. The results are explained by enhanced surface diffusion of gallium atoms on the surface of the carbon mask.

Im binären Mn-Ga-System wurde für Legierungen mit 55 at.% bis 65 at.% Mangan die Phasenbildung der L10-Phase mit Röntgenbeugung und Differenzialkalorimetrie untersucht. Nach der Herstellung der L10-Phase in allen Legierungen erfolgte eine Untersuchung der intrinsischen magnetischen Eigenschaften. Die Mn55Ga45-Legierung zeigte dabei die höchste Sättigungsmagnetisierung mit µ0Ms = 0,81 T. Für diese Legierung erfolgten deshalb Versuche zur Verbesserung der extrinsischen Eigenschaften. Dazu wurden Pulver gemahlen und die Möglichkeit der Ausrichtung im Magnetfeld untersucht. Dabei konnte ein Texturgrad von 0,45 für Pulver mit einer Partikelgröße kleiner 10 µm erreicht und die Koerzitivfeldstärke um das 7-fache gegenüber der Volumenprobe erhöht werden. Weiterhin konnten die Pulverproben durch Heißkompaktieren bei 400 °C erneut zu einer Volumenprobe gepresst werden. Die dabei erhaltene Probe besitzt eine Koerzitivfeldstärke von 0,16 T und eine leicht reduzierte Sättigungsmagnetisierung auf Grund einer Packungsdichte von 83 %. Im ternären Mn-Al-Ga-System wurden Proben der Sollzusammensetzung Mn55Al45-xGax mit 5,625 < x < 22,5 hergestellt. Für Legierungen mit x >= 11,86 erwies sich eine Wärmebehandlung bei 600°C für 24 Stunden als ausreichend die reine L10-Phase zu erzeugen. Bei den Legierungen mit einem geringeren Ga-Anteil war eine zweistufige Wärmebehandlung notwendig, um ausschließlich L10 zu erhalten. Nach der ersten Wärmebehandlung bei 1100 °C entstand ein Phasengemisch aus gamma2 und L10(epsilon). Letzteres wurde aus der epsilon-Hochtemperaturphase gebildet. Durch die anschließende Wärmebehandlung bei 500 °C für 24 Stunden konnte die verbleibende gamma2-Phase in L10(gamma2) umgewandelt werden. Untersuchungen der lokalen Legierungszusammensetzung ergaben einen geringeren Mn-Anteil der L10(gamma2)-Phase im Vergleich zu L10(epsilon). Die Unterschiede in den zwei L10-Phasen konnten weiterhin durch eine Reflexaufspaltung in den Röntgenbeugungsaufnahmen sowie der Existenz zweier Curie-Temperaturen bestätigt werden. Die gemessenen Sättigungsmagnetisierungen ergaben eine Superposition beider Phasen und einen maximalen Wert von µ0Ms = 0,85 T. Untersuchungen der thermischen Stabilität der L10-Phasen bei 700 °C zeigten, dass die L10(gamma2)-Phase thermisch stabil ist und sich die L10(epsilon)-Phase langsam in beta-Mn und gamma2 zersetzt. Bei der Zersetzung war im Vergleich zum binären Mn-Al-System eine starke Steigerung der thermischen Stabilität durch die Substitution geringer Mengen Galliums zu erkennen. Über die zersetzungsbedingte Reduktion der Magnetisierung konnten Abschätzungen der Zersetzungskinetik getroffen werden.

<p> The purpose of this work was to develop a growth pathway for synthesis of high-quality ferromagnetic Ni-Mn-Ga shape memory thin films and to understand their functional properties. </p> <p>Two groups of Ni-Mn-Ga films were prepared using the pulsed laser deposition technique. One group was grown on (100) YSZ ((Zr,Y)O2 with ZrO2:Y2O2=92:8) and was used to study the thermal, magnetic, and magnetocaloric properties. The other group was deposited on (100) MgO. These films were fabricated into free-standing micro-bridges.</p> <p>These Ni-Mn-Ga films were synthesized in a previously unexplored high temperature deposition regime. The temperatures employed encouraged the development of the desired micrometer-size highly twinned martensite grain structure while the general problem of preferential evaporation of the volatile elements at elevated temperatures was solved by using a manganese and gallium enriched target.</p> <p> The films grown on (100) YSZ exhibit a self-reversible, magnetically induced reorientation of the martensite variants (MIR), which is temperature dependent. The mechanism associated with the self-activated reversibility in the MIR effect was established through a detailed characterization of the texture, microstructure, and magnetic domain structure of the films. </p> <p> The synthesized films also show a large magnetocaloric effect (MCE), which is particularly strong at low magnetic fields. The effect is associated with an overlapped ferromagnetic and martensitic phase transition. Detailed characterization of these transitions allow for an understanding of the role each phase transition plays in determining the level of enhancement to a standard MCE governed only by the ferromagnetic phase transition.</p> <p> Ni-Mn-Ga free-standing micro-bridges were fabricated using photolithography followed by wet chemical etching. Microstructural evolution of the martensitic variants resulting from changes to the stress field in the detached areas was studied in the context of potential film applications for micro-actuators.</p> / Thesis / Doctor of Philosophy (PhD)

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