Surface microtopography affects fundamental hydrologic processes including infiltration and soil-water percolation at different scales. By means of studying the unsaturated flow, this thesis research is aimed to evaluate the effects of surface microtopography on wetting front moving patterns for rough soil surfaces through both experimental study and HYDRUS modeling. Additional influential factors such as rainfall intensity and soil type are also considered. Laboratory-scale infiltration and unsaturated flow experiments were conducted for different microtopographic surfaces, rainfall intensities, and types of soil; and two- and three-dimensional numerical modeling was conducted under the same conditions. The simulated and observed wetting front distributions were compared in this combined experimental and modeling study. It was found that a uniformly distributed wetting front was eventually achieved although soil surfaces had dissimilar topographic characteristics. However, the timing to reach the uniform flat wetting front varied, depending on surface microtopography, soil hydraulic properties, and boundary conditions. / Department of Civil Engineering, North Dakota State University / National Science Foundation (Grant No.EAR-0907588)

Microtopography is an important factor in hydrologic processes. The purpose of this research was to study the effects of microtopography on runoff generation. Specifically, this was performed through an array of physical experimentation comparing “rough” and “smooth” surfaces under natural and simulated rainfall. Utilizing these types of rainfalls required experimentation to take place in both field and laboratory settings. The range of control factors in this study varied from surface microtopography to soil type, rainfall intensity/pattern, and ambient moisture content. The recorded results of the laboratory study were further compared with the output of a puddle-to-puddle (P2P) overland flow model. The physical experiments showed a trend initially favoring neither the rough nor smooth surface in runoff production. However, in subsequent experiments the rough surface appeared to substantially increase runoff production relative to the smooth surface. Additionally, good agreement was found between the results of the physical experimentation and the model.

Orientador: Hélio Amante Miot / Banca: Ediléia Bagatin / Banca: Luciana Patrícia Fernandes Abbade / Resumo: A superfície cutânea é formada por microestruturas poligonais que permitem estimar sua textura e hidratação. A avaliação quantitativa dessa topografia proporciona estimativa da organização e função de estruturas cutâneas, permitindo análise de respostas terapêuticas a intervenções. O uso da fotografia digital microscópica para avaliação do microrelevo superficial pode contribuir para quantificação de aspectos visíveis da pele. Objetivos: Desenvolvimento e validação de sistema fotográfico digital de microscopia de superfície para avaliação quantitativa da topografia microscópica da pele. Métodos: Avaliou-se uma área de 0,25 cm2 de pele dos antebraços de 47 mulheres voluntárias, de fototipos II a IV. As imagens foram coletadas de modo padronizado utilizando-se Câmera Nikon® D70, empregando objetiva macro e lente polarizadora circular acoplados a dermatoscópio sem a lâmina de contato com a pele. Foram realizados experimentos para testar a influência da luminosidade externa, melhor canal de cor e validação da técnica a partir do uso de substância hidratante, avaliação da topografia microscópica da pele em relação à faixa etária e em relação à xerose cutânea sintomática sob tratamento imediato. Não se observou interferência da iluminação externa nas leituras de luminância média e na repetitividade nas medidas de dispersão dos pixels. O modo de cor que representou melhor desempenho quanto à reprodutibilidade e capacidade discriminatória foi o Gray. Os índices de complexidade textural que apresentaram melhor performance quanto à discriminação e reprodutibilidade das Larissa M. Chambô Cordaro Emprego da fotografia digital para avaliação da topografia microscópica da pele 47 amostras foram: Entropia, Ra, Rq e Dimensão fractal. O sistema foi capaz de detectar... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The skin surface is composed of fine lines intersecting each other and forming polygons which reflect its texture and hydration. A quantitative assessment of this topography estimates organization and biological functions of skin structure, can help to evaluate effectiveness of products and surgical techniques. Microscopic digital image analysis of the skin surface may be useful to amount the visually perceived skin changes. Purpose: To develop and validate a microscopic digital image analysis system to objectively assess quantitative measurements of skin microtopography. A 0,25cm2 area from 47 voluntary women forearms which skin phototypes was II to IV has been evaluated. Pictures have taken in a standardized way by a Nikon D70 camera, using macro lens and a parallel polarized filter attached to a dermoscopy set without skin contact plate. We have tested influence of external illumination, best color channel, and the technique was validated using a moisturizing substance. Correlation to age has been attempted using validated variables. Cutaneous xerosis treatment has been also estimated. External illumination has not influenced mean luminance and the repetitivity of pixels dispersion measures. Gray channel has represented best reproductiblity and discriminatory characteristics. Entropy, Ra, Rq and Fractal dimension were complexity indexes with best textural performances. The system has been able to detect significative differences between forearms surface topography before and after moisturizing in healthy or xerotic skin patients. There has not been true correlation between validated textural indexes and age. Conclusions: A photographic method to objectively assess microscopic skin topography has been developed and validated to immediate skin moisturizing. A low Larissa M. Chambô Cordaro Emprego da fotografia... (Complete abstract click electronic access below) / Mestre

Surface microtopography affects a series of complex and dynamic hydrologic and environmental processes that are associated with both surface and subsurface systems, such as overland flow generation, infiltration, soil erosion, and sediment transport. Due to the influence of surface depressions, overland flow essentially features a series of progressive puddle-to-puddle (P2P) filling, spilling, merging, and splitting processes; and hydrologic systems often exhibit threshold behaviors in hydrologic connectivity and the associated overland flow generation process. It is inherently difficult to realistically simulate the discontinuous overland flow on irregular topographic surfaces and quantify the spatio-temporal variations in dynamic behaviors of topography-dominated hydrologic systems. This dissertation research aims to develop a hydrologic model to simulate the discontinuous, dynamic P2P overland flow processes under the control of surface microtopography for various rainfall and soil conditions, and propose new approaches to quantify hydrologic connectivity. In the developed P2P overland flow model, the depressions of a topographic surface are explicitly incorporated into a well-delineated, cascaded P2P drainage system as individual objects to facilitate the simulation of their dynamic behaviors and interactions. Overland flow is simulated by using diffusion wave equations for a DEM-derived flow drainage network for each puddle-dominated area. In addition, a P2P hydrologic connectivity concept is proposed to characterize runoff generation processes and the related spatio-temporal dynamics. Two modified hydrologic connectivity indices, time-varying connectivity function and connectivity length of the connected areas and ponded areas, are proposed to quantitatively describe the intrinsic spatio-temporal variations in hydrologic connectivity associated with overland flow generation. In addition, the effects of DEM resolution, surface topography, rainfall distribution, and surface slope on hydrologic connectivity are also evaluated in this dissertation research. The developed model can be applied to examine the spatio-temporally varying P2P dynamics for hydrologic systems. This model provides a means to investigate the effects of the spatial organization/heterogeneity of surface microtopography, rainfall, and soil on overland flow generation and infiltration processes. In addition, the two proposed hydrologic connectivity indices are able to bridge the gap between the structural and functional hydrologic connectivity and effectively reveal the variability and the threshold behaviors of overland flow generation. / National Science Foundation under Grant No. EAR-0907588 / Department of Civil and Environmental Engineering, North Dakota State University / North Dakota Water Resources Research Institute

Spatial characterization of surface microtopography is important in understanding the overland flow generation and the spatial distribution of surface runoff. In this study, fractal parameters (i.e., fractal dimension D and crossover length l) and three hydrotopographic parameters, random roughness (RR) index, maximum depression storage (MDS), and the number of connected areas (NCA), have been applied to characterize the spatial complexity of microtopography. Clear and meaningful relationships have been established between these parameters. The RR was calculated as the standard deviation of the processed elevation, and the fractal parameters were calculated with the semivariogram method. The puddle delineation program was applied in this study to spatially delineate soil surface and to accurately determine MDS and NCA. It has been found that fractal parameters can better characterize surface microtopography. More importantly, fractal and anisotropic analyses can help to better understand the overland flow generation process.

Wetlands self-organize through reciprocal controls between vegetation and hydrology, but external disturbance may disrupt these feedbacks with consequent changes to ecosystem state. Imminent and widespread emerald ash borer (EAB) infestation throughout North America has raised concern over possible ecosystem state shifts in forested wetlands (i.e., to wetter, more herbaceous systems) and loss of forest function, calling for informed landscape-scale management strategies. In this dissertation, I use black ash wetlands as a model system to understand complex ecohydrological dynamics, and I use these dynamics to explain the self-organization of observed patterns in vegetation, hydrology, and microtopographic structure. The combined inferences from the three research chapters strongly implicate black ash trees as autogenic ecosystem engineers, who, through the process of improving their local growing conditions, cause a cascade of environmental changes that result in a unique ecosystem structure. This unique ecosystem structure is under existential threat from the invasive EAB. Through experiment, I show that loss of black ash trees to EAB induces persistent shifts in hydrology that result from reduced evapotranspiration and subsequent changes to water table regime (Chapter 2). These results suggest the potential for catastrophic shifts of black ash wetlands from forested to non-forested, marsh-like states under a do-nothing EAB management scenario. However, research presented here suggests that preemptive management of black ash wetlands can potentially mitigate loss of desirable forested conditions. Forest management to replace black ash with other wetland canopy species may be a slow and steady path towards forest maintenance, and harvesting may facilitate establishment of alternative species. In the case of preemptive harvesting of black ash, I posit that maintenance of microtopographic structure, either through leaving downed woody debris or through physical creation, is paramount to forest recovery. Microtopography in these ecosystems provides crucial relief from anaerobic stress generated by higher water tables, allowing woody species to persist on elevated microsites (e.g., 30 cm above base soil elevation). Moreover, I show that microtopography in black ash wetlands has clear structure and pattern and that its presence arises from self-organizing processes, driven by feedbacks among hydrology, biota, and soils (Chapter 3). I further show that this structured and non-random microtopography has profound influence on biogeochemical processes in black ash wetlands, controlling plant richness and biomass, and soil chemistry gradients (Chapter 4). Based on this work, I propose that structured wetland microtopography is a diagnostic feature of strongly coupled plant-water interactions, and these interactions may be important for ecosystem resilience to disturbance. / Doctor of Philosophy / Plants need water, but not too much nor too little. In wetland ecosystems, plants influence water levels through both water use and their effect on soil surfaces. When wetland plants use water, they take it from the soil, which leads to lowering of water levels and drier soil conditions. In many wetlands, the amount of water that plants take from the soil is a fine-tuned process. Therefore, when disturbances happen to wetland ecosystems, like large-scale tree mortality, major changes can occur to the amount of water in the soil and soils typically become wetter. This change to a wetter ecosystem can persist for long periods, and can affect the types of plants that can live in the wetland. However, plants also affect wetland water levels by engineering the soil around them, essentially lifting themselves to drier conditions. Through this engineering, plants create a mosaic of different habitat types that are important for many organisms and ecological processes. Exactly how plants engineer their environment is still not well understood, but we know that ecosystem engineering by plants is critical to the structure and function of wetlands around the world. Understanding how plants create and maintain their own environmental structures provides a deeper insight into the development of vegetated landscapes and their response to change. This dissertation aims to improve our understanding of ecosystem engineering by plants in forested wetlands so that we may more effectively manage these important natural resources and in turn more accurately predict their response to global change.

Skin wound healing presents a challenging and expensive clinical problem with nearly 20 million wounds requiring intervention leading to an annual cost of more than $8 million. Tissue engineered skin substitutes are valuable not only as a clinical therapy for chronic wounds and severe traumas, but also as in vitro 3D model systems to investigate wound healing and skin pathogenesis. However, these substitutes are limited by a lack of topography at the dermal-epidermal junction (DEJ). In contrast, the native DEJ is characterized by a series of dermal papillae which project upward into the epidermal layer and create physical topographic microniches that support keratinocyte stem cell clustering. In this thesis, we created novel 3D skin model systems to investigate the role of microtopography in regulating keratinocyte function and cell fate using scaffolds containing precisely engineered topographic features. We hypothesized that the microtopography of the DEJ creates distinct keratinocyte microniches that promote epidermal morphogenesis and modulate keratinocyte stem cell clustering which can be harnessed to create a more robust skin substitute that expedites wound closure. Using photolithographic techniques, we created micropatterned DEJ analogs and micropatterned dermal-epidermal regeneration matrices (µDERM) which couple a dermal support matrix to a micropatterned DEJ analog. We found that the incorporation of microtopography into our in vitro skin model resulted in a thicker, more robust epidermal layer. Additionally, we identified three distinct functional keratinocyte niches: the proliferative niche in narrow channels, the synthetic niche in wide channels and the keratinocyte stem cell niche in narrow channels and corner topographies. Ultimately, incorporation of both narrow and wide channels on a single construct allowed us to recreate native keratinocyte stem cell patterning in vitro. These model systems will allow us to investigate the role of cellular microniches in regulating cellular function and epidermal disease pathogenesis as well as to identify topographic cues that enhance the rate of wound healing.

Made available in DSpace on 2014-06-11T19:27:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-09-01Bitstream added on 2014-06-13T20:36:39Z : No. of bitstreams: 1 cordaro_lmc_me_botfm.pdf: 603704 bytes, checksum: c88834ac9aafa63013e26147e51e24d1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A superfície cutânea é formada por microestruturas poligonais que permitem estimar sua textura e hidratação. A avaliação quantitativa dessa topografia proporciona estimativa da organização e função de estruturas cutâneas, permitindo análise de respostas terapêuticas a intervenções. O uso da fotografia digital microscópica para avaliação do microrelevo superficial pode contribuir para quantificação de aspectos visíveis da pele. Objetivos: Desenvolvimento e validação de sistema fotográfico digital de microscopia de superfície para avaliação quantitativa da topografia microscópica da pele. Métodos: Avaliou-se uma área de 0,25 cm2 de pele dos antebraços de 47 mulheres voluntárias, de fototipos II a IV. As imagens foram coletadas de modo padronizado utilizando-se Câmera Nikon® D70, empregando objetiva macro e lente polarizadora circular acoplados a dermatoscópio sem a lâmina de contato com a pele. Foram realizados experimentos para testar a influência da luminosidade externa, melhor canal de cor e validação da técnica a partir do uso de substância hidratante, avaliação da topografia microscópica da pele em relação à faixa etária e em relação à xerose cutânea sintomática sob tratamento imediato. Não se observou interferência da iluminação externa nas leituras de luminância média e na repetitividade nas medidas de dispersão dos pixels. O modo de cor que representou melhor desempenho quanto à reprodutibilidade e capacidade discriminatória foi o Gray. Os índices de complexidade textural que apresentaram melhor performance quanto à discriminação e reprodutibilidade das Larissa M. Chambô Cordaro Emprego da fotografia digital para avaliação da topografia microscópica da pele 47 amostras foram: Entropia, Ra, Rq e Dimensão fractal. O sistema foi capaz de detectar... / The skin surface is composed of fine lines intersecting each other and forming polygons which reflect its texture and hydration. A quantitative assessment of this topography estimates organization and biological functions of skin structure, can help to evaluate effectiveness of products and surgical techniques. Microscopic digital image analysis of the skin surface may be useful to amount the visually perceived skin changes. Purpose: To develop and validate a microscopic digital image analysis system to objectively assess quantitative measurements of skin microtopography. A 0,25cm2 area from 47 voluntary women forearms which skin phototypes was II to IV has been evaluated. Pictures have taken in a standardized way by a Nikon D70 camera, using macro lens and a parallel polarized filter attached to a dermoscopy set without skin contact plate. We have tested influence of external illumination, best color channel, and the technique was validated using a moisturizing substance. Correlation to age has been attempted using validated variables. Cutaneous xerosis treatment has been also estimated. External illumination has not influenced mean luminance and the repetitivity of pixels dispersion measures. Gray channel has represented best reproductiblity and discriminatory characteristics. Entropy, Ra, Rq and Fractal dimension were complexity indexes with best textural performances. The system has been able to detect significative differences between forearms surface topography before and after moisturizing in healthy or xerotic skin patients. There has not been true correlation between validated textural indexes and age. Conclusions: A photographic method to objectively assess microscopic skin topography has been developed and validated to immediate skin moisturizing. A low Larissa M. Chambô Cordaro Emprego da fotografia... (Complete abstract click electronic access below)

Alpine plant communities can be exceptionally diverse at a fine scale, and they often exhibit fine scale topographic variability. High species diversity is often attributed to spatial and temporal heterogeneity in the environment. The goal of this study was to test for a positive relationship between microtopographic heterogeneity and species diversity of alpine plants. Species diversity of vascular plants was sampled at 8 sites in Glacier National Park, MT during the summer of 2009. Species richness was assessed both within a 1 x 1 m plot and at 100 points spaced 10 cm apart within the plot. To quantify topographic heterogeneity and variability, the relative elevation was measured for all 100 points in the plot as well. Similarity in species composition between study plots was investigated using Non-Metric Multidimensional Scaling. The study plots separated into two groups based on the presence/absence of Dryas octopetala. This difference is most likely due to plots occupying different positions along the mesotopographical gradient and therefore experiencing different moisture regimes. Regression for all 1 m2 plot data found a negative relationship between topographic heterogeneity and species richness, and no relationship between topographic variability and species richness. Quantile regression was used to assess the relationship between point measures of species richness and topographic variability. There is evidence for topographic variability imposing a limit on species richness for all sites grouped together and for sites that do not contain D. octopetala. This limit is most likely due to the interaction of soil disturbance and the productivity of a site.

Tidal freshwater forest restoration after dam removal has been unexplored to date. This study elucidated pre-dam forest composition, as well as post-dam edaphic and microtopographical attributes and woody species recruiting along a narrow ecotone of a 29.3-ha tidal freshwater wetland. The ≈65-year-old historical forest (15 species, 200 stems ha-1) and ≈7-year-old contemporary forest (40 species and 11,009 stems ha-) community dominants were dissimilar (Fraxinus spp. vs. Liquidambar styraciflua, respectively). Pre-dam environmental conditions were unknown. Post-dam edaphic water content, organic matter, redox potential and microtopography differed significantly across tidal sites but were less variable in non-tidal sites. Shifts in the contemporary woody community composition and the concomitant increase in stem density and seedling:sapling ratios with elevation likely owed to significant changes in microtopography and edaphic attributes. Developing ecotones that contain variable microtopography may be extremely important for successful natural woody recruitment after dam removal from a tidal freshwater system.