The central nervous system is a complex, yet well-organised, often laminated, tissue. This robust organisation is evident in the architecture of the retina: consisting of 5 different neuronal types organised into distinct layers: Retinal Ganglion Cell (RGC), Amacrine Cell (AC), Bipolar Cell (BP), Horizontal Cell (HC) and Photoreceptor cell (PR) layers. This remarkable organisation is evolutionarily conserved in vertebrates, yet little is known about the mechanisms by which these cells form the correct layers. Live imaging has revealed overlapping periods of birth and extensive inter-digitation followed by cells sorting out into their appropriate positions, suggesting cell-cell interactions are important. To investigate possible cellular and molecular mechanisms responsible for the establishment of the tissue architecture I developed an organoid culture system for zebrafish retinal cells. To identify the cells in culture I used a Spectrum of Fates fish line which is a multiply transgenic line in which each retinal cell type can be identified based on expression of a combination of fluorescently tagged cell fate markers. The development of the protocol by which I cultured the cells and observed their cell-cell interactions involved establishing the best methods to dissociate and culture zebrafish retinal cells in a non-adhesive environment, then imaging the resulting reaggregates to examine the position of the different retinal cell types. By doing this I observed their inherent self-organising properties, in the absence of extrinsic cues or scaffolds. These cells appeared to be arranged in an inside-out layering, although all cell types are layered in the same relative order as they are in vivo. To analyse the organization in these aggregates I developed a Matlab script in collaboration with Leila Muresan which analyses the relative positioning of cells in concentric rings from the periphery to the centre of the aggregates according to the cell fate-tagged fluorescent markers. The script then fits this data as an empirical cumulative distribution function for different groups of cells to determine how spatially distinct populations of cells are. This gave me my measure of organisation. I then investigated the cell-cell interactions involved in this self-organisation by genetically or pharmacologically removing individual cell types and assaying the resulting organisation of the reaggregated, cell-type deficient, retinal organoids. I revealed that Müller Glia are important for retinal cell self-organisation. I also investigated the role of Retinal Pigment Epithelial (RPE) cells and Retinal Ganglion Cells and found they had no impact on the ability of the remaining cell types to organize. I began to investigate the role of Amacrine Cells but found that retinas void of ACs were susceptible to disaggregating in our dissection setup, preventing me from collecting the material needed for culture. I also investigated the role of candidate molecules in this system and revealed that R-Cognin is critical for retinal cells to reaggregate. Not only can I remove cells or molecules from the system, but I show how it can also be manipulated to replace molecules of interest such as laminin, by coating beads with the substance of choice and placing it amongst the cells to see if their organisational behaviour is affected. In summary, I have developed a system which provides a simple and easy platform to manipulate in various ways to help us potentially reveal some of the important players in neuronal patterning.

Além de ser plantado comercialmente, o cambucizeiro pode ser utilizado na recuperação de áreas degradadas, apresentando frutos com potencial de exploração para consumo humano, in natura ou na forma processada. As mudas para a implantação dessa espécie geralmente são obtidas de sementes, o que resulta em grande variabilidade genética dentro das populações e desfavorece a fixação de genótipos superiores em relação a produção e qualidade de frutos. Por esses motivos, é importante conhecer a fisiologia das sementes, a emergência e o desenvolvimento das plântulas e avaliar quais técnicas de multiplicação vegetativa melhor se adaptariam a essa espécie. Portanto, o objetivo deste trabalho foi verificar a interferência da dessecação de sementes sobre a ocorrência de protrusão radicular e formação de plântulas normais de cambucizeiro, assim como a influência do uso de diferentes substratos na emergência e desenvolvimento inicial de suas plântulas e avaliar as técnicas de estaquia, alporquia e enxertia na produção de mudas dessa espécie. De forma geral, as sementes de cambucizeiro quando dessecadas até níveis de 15% de água não mostraram perda de viabilidade, o substrato vermiculita garantiu uma melhor emergência das plântulas, entretanto, foram os substratos Basaplant® e a mistura turfa + perlita que garantiram o melhor desenvolvimento inical das mesmas. Quanto as técnicas de multiplicação vegetativa, a estaquia e alporquia mostraram-se ineficientes para o cambucizeiro, não apresentando enraizamento, já a enxertia do tipo fenda lateral garantiu a fixação de 6% dos enxertos podendo ser usada na fixação de genótipos superiores. Após os resultados negativos das técnicas de enraizamento adventício, análises anatômicas foram realizadas e indicaram que a presença de compostos fenólicos pode estar influenciando mais no processo de formação de raízes adventícias do que o impedimento físico das faixas de esclerênquima. / Despite the potencial of being commercially cultivated, the cambuci tree can be used for recovering degraded areas; its fruits present potential to be exploited for human consumption, in natura or in the processed form. Cambuci tree seedlings are usually obtained from seeds, which results in genetic variability within the population, disfavouring the fixation of superior genotypes in relation to fruit production and quality. For this reason, it is important to know seed physiology, emergence and development of seedlings and to evaluate which vegetative propagation technique would best suit this species. Therefore, the aim of this work was to verify the interference of seed desiccation on the occurrence of root protrusion and the formation of normal cambuci tree seedlings, as well as the influence of the use of different substrates in the emergence and initial development of their seedlings and to evaluate the techniques of cutting, air layering and grafting in the production of seedlings of this species. In general, cambuci tree seeds when dessicated until levels of 15% of water content did not show loss of viability, the substrate vermiculite guaranteed a better emergence of the seedlings, however, it was the Basaplant® substrats and the peat and perlite mixture that guaranteed a better emergence of the seedlings. as for the vegetative propagation techniques, the use of cuttings and air layerings were inefficient for this species, showing no adventitious rooting, on the other hand, side-veener graft ensured 6% of scion fixation, which could be used to fix superior genotypes. After the negative results of the adventitious rooting techniques, anatomical analysis were performed and indicated that the presence of fenolic coumponds may be more influential in the adventitious root formation process than the physical barrier formed by layers of sclerenchyma tissue.

An architectural framework is proposed to secure the data link layer (Layer 2) in Internet protocol (IP) over Ethernet networks. In this architecture, a new security inter-layering concept, incorporating cryptographic Layer 2 identities, is introduced. Instead of traditional media access control (MAC) addresses, secure and flexible data link layer identifiers are utilized to securely bind Layer 2 and upper layers. In addition, to create security parameters and negotiate identifiers at the data link layer, a key establishment protocol is presented. Moreover, this architecture incorporates the IEEE 802.1AE standard (MACsec) and uses a key hierarchy similar to the IEEE 802.11i standard for future compatibility of wired and wireless networks. Finally, we provide a security analysis of the new data link layer security architecture.

In the first part of this thesis, we present results from extensive molecular dynamics simulations of the collapse transitions of hydrophobic polymers in explicit water. The focus is to understand the roles that curvature and interactions associated with the polymer-water “interface” have on collapse thermodynamics. We show that model hydrophobic polymers can have parabolic, protein-like, temperature-dependent free energies of unfolding. Analysis of the water structure shows that the polymer-water interface can be characterized as soft and weakly dewetted. We also show that an appropriately defined surface tension for the polymer-water interface is independent of the attractive polymer-water interactions. This helped us to develop a perturbation model for predicting the effect of attractions on polymer collapse thermodynamics. In the second part, we explore connections between structure, thermodynamics, and dynamics of inhomogeneous fluids. First, we use molecular dynamics simulations and classical density functional theory (DFT) to study the hard-sphere fluid at approximately 103 equilibrium state points, spanning different confining geometries and particle-boundary interactions. We provide strong empirical evidence that both excess entropy and a new generalized measure of available volume for inhomogeneous fluids correlate excellently with self-diffusivity, approximately independent of the degree of confinement. Next, we study via simulations how tuning particle-wall interactions to flatten or enhance the particle layering of a model confined fluid impacts its self-diffusivity, viscosity, and entropy. Interestingly, interactions that eliminate particle layering can significantly reduce confined fluid mobility, whereas those that enhance layering can have the opposite effect. Excess entropy helps to understand and predict these trends. Finally, we explore the relationships between the effective interparticle interactions, static structure, and tracer diffusivity of a solute in a mixture. We show that knowledge of these relationships can allow one to “tune” the effective interparticle interactions of the solute in a way that increases its tracer diffusivity. One interesting consequence is that the mobility of a hard-sphere solute can be increased by adding a soft-repulsion to its interaction, effectively making it bigger. / text

Made available in DSpace on 2015-04-11T13:56:25Z (GMT). No. of bitstreams: 1 JANUARIO_M_V_JUNIOR.pdf: 1674858 bytes, checksum: faa0697a13049e8a8c13e8c3021e7002 (MD5) Previous issue date: 2011-05-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Amazon is the largest reserve of natural products with potential herbal medicine on the planet and its population uses them empirically for these purposes. But deforestation, associated with predatory extraction practices, has led to the decline and genetic erosion, which may lead to extinction of these species. Among the many plants that are used by the population to treat various ailments, is saracura-mirá (Ampelozizyphus amazonicus Ducke), also known as indian beer, which is widely used by the Amazonian population for the treatment of various diseases, especially the use as a prophylactic measure against malaria, which already had its efficacy proven through laboratory testing. This study aimed to assess the ways of propagation of the species Ampelozizyphus amazonicus. Young seedlings of the natural range were acclimatized and planted in three different environments: full sun, the area of primary forst and woodland area shaded by Ochroma pyranidale, the seedlings planted in the grove had 100% survival, while other areas 88% each. In sexual propagation, the seeds were germinated in four different substrates: S1-commercial substrate, S2-substrate area of natural occurrence of the species, S3-organic compound and S4- washed sand in a randomized design with four replications each. Were counted germinated seeds every two days. The results of germination and emergence rate index (EVI) were compared by statistical analysis. The variable germination showed no statistical difference between treatments, showing that the substrate does not affect the germination process. Since the variable EVI show differences between treatments S2 and S4, were S4 had the highest average and the lowest S2. Vegetative propagation by layering different pre-tested layering treatments: 12 annealing total, partial ring, and strangulation by wire, and four concentrations of IBA (0, 500, 1000 e 2000 ppm). Independent factor in pre-treatment of layering, strangulation by wire, and had higher average total annealing treatment with the lowest averages for these variable, and the individual factor concentration of IBA, layers treated with 2000ppm had higher averages. In asexual propagation by cuttings were tested different concentrations of growth hormone regulating acid butyl indole (and four concentrations of IBA 0, 500, 1000 and 2000 ppm) and different substrates, three types: washed sand, soil natural area of the species and composed commercial, in a completely randomized design in a factorial 3 x 4. Statistical analysis showed no statistical difference between treatments. Factor in the substrate, treatment whit washed sand showed the highest averages for the % survival, number of roots and number of sprouts. In the IBA concentration factor, treatments at a concentration of 1000 ppm had higher averages in the variables % survival rate and number of sprouts. A. amazonicus indicates the possibility of cultivation. / A Amazônia é a maior reserva de produtos naturais com potencial fitoterápico do planeta e a sua população emprega-os empiricamente para esses fins. Mas o desmatamento, associado a pratica extrativista predatória, vem provocando a diminuição, bem como a erosão genética, podendo levar até a extinção dessas espécies. Dentre as inúmeras plantas que são utilizadas pela sua população para tratar diversos males, está a saracura-mirá (Ampelozizyphus amazonicus Ducke), também conhecida como cerveja-de-índo, que é bastante utilizada pela população amazônica para o tratamento de diversas enfermidades, destacando-se o uso como medida profilática contra a malária, que já teve sua eficácia comprovado através de testes em laboratório. O presente trabalho objetivou avaliar as formas de propagação da espécie Ampelozizyphus amazonicus. Mudas jovens da área de ocorrência natural foram aclimatadas e plantadas em três diferentes ambientes: a pleno sol, área bosqueada de floresta primária e área sombreada por Ochroma pyramidale, as mudas plantadas na área bosqueada apresentaram 100% de sobrevivência, enquanto as demais áreas 88% cada. Na propagação sexuada, as sementes foram postas para germinar em quatro diferentes substratos, sendo: S1-substrato comercial, S2-substrato da área de ocorrência natural da espécie, S3-composto orgânico e S4-areia lavada no delineamento experimental inteiramente casualizado com quatro repetições cada. Foram feitas contagens de sementes germinadas a cada dois dias. Os resultados de porcentagem de germinação e índice de velocidade de emergência (IVE) foram comparados por análise estatística. A variável germinação não apresentou diferença estatística entre os tratamentos, mostrando que os substratos não tiveram influência no processo germinativo. Já 10 a variável IVE mostrou diferença entre os tratamentos S4 e S2, onde S4 apresentou a maior média e o S2 à menor. Na propagação vegetativa por via alporquia foram testados diferentes pré-tratamentos de alporquia: anelamento total, anelamento parcial, e estrangulamento por arame, bem como quatro concentrações de AIB (0, 500, 1000 3e 2000 ppm). No fator independente pré-tratamento de alporquia, o estrangulamento por arame, apresentou maiores médias e o tratamento com anelamento total as menores médias em relação às variáveis estudadas, e no fator individual concentração de AIB, alporques tratados com 2000 ppm apresentaram maiores médias. Na propagação assexuada por via estaquia, foram testadas diferentes concentrações do hormônio regulador de crescimento ácido indol butílico (e quatro dosagens de AIB (0, 500, 1000 e 2000 ppm) e diferentes substratos, sendo três tipos: areia lavada, solo da área natural da espécie e composto comercial, no delineamento inteiramente casualizado em esquema fatorial 3 x 4. A análise estatística mostrou que não houve diferença estatística entre os tratamentos. No fator substrato, o tratamento com areia lavada foi o que apresentou maiores médias para as variáveis % de sobrevivência, número de raiz e número de brotos. Já no fator dosagem de AIB, os tratamentos na dosagem de 1000 ppm apresentaram maiores médias nas variáveis % de sobrevivência e número de brotos. A. amazonicus indica possibilidade de cultivo.

This degree work explores the possibilities of illusory print expressions in fashion design, through the layeringand gathering of opaque and transparent garments. The three-dimensional illusion, in the silhouettes, createan interesting relationship between multiple layering of garment and print. In combination they expressdepth, movement and deception on the human body resulting in an interesting effect that creates an opticalillusion. The discovery of illusionary effect is a result of multiple investigations between diverse prints invarious materials gathered in layers. Depending on which angle the viewer look, different visual illusionsappear and activates the feeling of movement and three-dimensional illusion on the human body. The effectof utilizing different tactility surfaces in the concept of layering is a new visual expression in dressing. Theoutcome should be seen as a motivation to explore and translate things around us by transforming the worldinto a print and decorate it on the body in multiple layers and colors.

’Point of view’ is an investigation of changeable surface patterns in the textile design field. The investigation is performed in order to get a deeper understanding of the relationship between changeable surface patterns and three-dimensional contexts to explore alternative methods.  The aim is to design surface patterns in a three dimensional context developed through printing and layering techniques, and to explore how the patterns change depending on the observer’s perspective. Practice based design experiments were carried out to explore materials and printing techniques such as transfer, digital and burn out. The patterns were in turn placed on a cubic frame with inner and outer layers, and studied for their effects on one another.  The project resulted in a series of surface patterns that were applied in a spatial context. The findings propose an alternative method for designing changeable surface patterns in a three-dimensional setting, using layers, transparency and distance as factors.

In my diploma thesis I want to deal with another topic which is very interesting and important for me and that is organ and organ music in general and everything that belongs to them. From history, production, maintenance to play itself. In most of my previous works, not only at college but also earlier, fragments of this instrument appear in my paintings (mainly whistles, which are actually the most visible and their size determines the size of whole organs and is their precept) even though I have devoted myself on another topic, these fragments I had some need to plant there.  Organs are referred to as the royal instrument, they are the largest and mechanically the most complicated musical instrument. That is the complexity I would like to express in my pictures, I do not mean the complexity of the organ for the technical, construction, but especially the complexity of playing. The need for the right combinations of different registers with differently colored tones and tools. Swap pedal handbooks, etc. This is all about fascination for me.  In this diploma thesis I want to use the themes that appeared on the surface often as secondary or I did not put such emphasis or were the main topic for example only one semester, but in fact I continued to work with them subconsciously in the same way, Layers, Recycling, Reaction to Substrates, etc. It could be said that such organ compositions are such layers as Bach's or any fugues that are gradually being added, layers of new and new tones often result in the the full extent that the organ is able to administer.  The layer I used to work with before, and actually always appears in my works, has actually become an integral part of my paintings. I want to express the complexity of the organ compositions in my paintings, as I do. Not only by layering, but also by using different techniques, not just acrylic. I also used this in my previous work, and examined how they work with each other. I have responded to differently produced backgrounds.  Organ music can be considered complicated because all we hear is produced by one person. Who must play and cater everything else that is associated with it, except perhaps the bells pedaling.  This series of images will not, in the end, express myself visually, at first sight nothing concrete, over time I have come to a pretty abstract image. I do not mean to say that organ music is abstract, especially if I talk about Baroque or Classicism. Maybe in romanticism, for example, F. Liszt and his organ compositions are so complex and terribly crazy that I might consider them quite abstract. But just the organ music of Liszt, which I admire most, I think it is not possible to express it in abstract form. It's a mad, complicated tangle of different, tones, colors, games with registers, blinds, and so on, and I want to express it all on the canvas.

Adaptiveve [re]use is a process that makes use of the principles of [re]duce, [re]use and [re]cycle, often giving products an extended lifespan not initially associated with the original function. Environmentally adaptive [re]use makes sense as the embodied energy of the host building is [re]tained opposed to the amount of energy [re]quired to construct an entirely new building. The purpose of the urban group framework was to increase density within the city and provide a wider range of commercial, social and cultural activities that take place in a 24 hour cycle. Another aim was to [re]store existing buildings within the city, [re]juvenating the area and its surrounds. The design strategy of this thesis was to investigate how new interventions could be in contrast to the existing building. This was achieved by allowing new structures to be read differently from the host building. The contrasting use of materials and construction technologies [re]sulted in an architectural language of “lightness”, allowing new components to be sensitively inserted into the existing building. Additionally the design strategy included the exploration of layering and place making. Layering involved the preservation of the original building’s form and identity, while new structures are layered over the existing in order to create new spaces. Place making was achieved by adding new hanging structures to the northern and southern façade in turn articulating new functional spaces. All new adaptations and interventions are constructed in such a manner so as not to hamper the flexibility and future adaptability of the building. / Dissertation (MArch(Prof))--University of Pretoria, 2010. / Architecture / unrestricted

Jacket plum [ Pappea capensis ( Eckl.&Zeyh)] belongs to the Sapindaceae or Litchi family. It is well adapted to different climatic conditions. It has been used for medicinal purposes for both animals and human beings. Due to the richness of seeds in oil, it has great potential to be selected for production of biodiesel in South Africa. Suitable vegetative propagation methods for Pappea capensis trees have not yet been investigated and sexual propagation does not produce true-to-type plants, which take many years to bear fruits. Therefore, research was carried out to identify alternative methods for vegetative propagation of Pappea capensis which could be used for rapid multiplication. Several vegetative propagation experiments were carried out with stem cuttings and air layers. Stem cuttings were collected from two mature Pappea capensis trees grown at the Experimental Farm of the University of Pretoria in the spring and autumn seasons. The cuttings were placed for rooting on the mist bed for rooting with and without Seradix® No. 2 [active ingredient, indolebutyric acid (IBA)] treatment. Other experiments followed in which the branches were girdled before making stem cutting to improve the level of any carbohydrates or available carbohydrates. Trials to investigate the rooting potential of Pappea capensis coppices, using different stem lengths, were also conducted. Rooting of Pappea capensis stem cuttings was unsuccessful. Air layers were made on the same trees where cuttings were collected. The trials were conducted in the spring and autumn seasons from 2006, 2007 and 2008. Some air layers were treated with Seradix® No. 2 and others were not treated with the auxin. High rooting percentages (100% in spring, 60% in autumn) were achieved with untreated air layers of Tree No. 1 and Tree No. 2 (80% in spring, 40% in autumn). Regardless of season, IBA and tree treatments, rooting was successful when the air layering method was used. Due to inconsistency in rooting from both vegetative methods, total phenolic compounds were extracted. The Folin-Ciaocalteau reagents method was used to extract phenolic compounds and the results were detected with Elisa reader instrument. The stem cuttings and air layers were further analysed for carbohydrates (starch and soluble sugars) with ó-toluidine reagent and ethanol and read with Spectrophotometer and high performance liquid chromatography (HPLC). Higher levels of total phenol compounds were observed from callused (27.13 mg/g) and non rooted untreated (26.41 mg/g) stem cuttings from Tree No. 2, compared to IBA treated stem cuttings (19.90 mg/g) of callused and non rooted IBA treated stem cuttings (20.25 mg/g) of Tree No. 2. High total phenols (34.55 mg/g) in untreated air layers were also found in callused air layers of Tree No. 2 and lower amounts (22.85 mg/g) in treated air layers of the same tree. No soluble sugars were detected in stem cuttings or air layers with HPLC. Regarding starch, higher amounts were observed in stem cuttings of Tree No. 1 (18.45 mg/g) of the control and Tree No. 2 (19.82 mg/g) of IBA treated cuttings. Most of the air layers made on Tree No. 1 had higher percentages of starch, with the exception of the callused (7.41 mg/g) air layers of the control. Tree No. 2 air layers had very low amounts of starch when compared with those of Tree No. 1. The variation in rooting potential of stem cuttings and air layers led to the consideration of tree gender as a factor influencing success rates, where inflorescences were collected from the two Pappea capensis trees for two years (2007 and 2008). The microscopic investigations showed that Pappea capensis trees (Tree No. 1 and Tree No. 2) were monoecious, however, Tree No. 2 switched from monoecious to male by producing only male flowers. Based on the results of the above investigations, air layering in the spring season can be used as a (alternative) vegetative propagation method for Pappea capensis tree, but on specifically monoecious tree to obtain higher rooting percentage. However, these are preliminary trials which require further investigation. / Dissertation (MSc(Agric))--University of Pretoria, 2010. / Plant Production and Soil Science / unrestricted