A imprecisão das estimativas de carbono estocado em florestas naturais no ciclo global de carbono vem criando uma demanda de desenvolvimento e padronização de métodos indiretos para modelagem deste ciclo e de emissões de CO2 provenientes de mudanças de uso da terra e florestas. O trabalho teve como objetivo estabelecer as relações empíricas existentes entre a biomassa e o estoque de carbono de uma Floresta Ombrófila Mista (FOM) e os dados ópticos provenientes de sensores remotos de média resolução espacial (ASTER, LiSSIII e TM) por meio de análise de regressão. Além disso, criou-se um cenário hipotético de Redução de Emissões por Desmatamento, Degradação Florestal e Aumento de Estoque de Carbono (REDD+). O estudo foi desenvolvido na Estação Experimental de São João do Triunfo, no estado do Paraná. As equações de regressão envolveram como variáveis dependentes (y): a biomassa e o carbono florestal, obtidos indiretamente do inventário florestal contínuo do Programa de Pesquisas Ecológicas de Longa Duração (PELD), e como variáveis independentes (x) as bandas espectrais e os índices de vegetação (IV). O tratamento estatístico envolveu a análise da matriz de correlação (r) entre as variáveis x e y; a análise de regressão linear simples, não linear e múltipla, com as seguintes estatísticas: R², R²aj., Syx, Syx% e dispersão dos resíduos, Por fim, elaboraram-se mapas temáticos para estas variáveis biofísicas. Como as correlações (r) entre as variáveis biofísicas e espectrais do sensor ASTER (15m) foram baixas, a imagem foi degradada para 30m e 45m. Na resolução de 30m, o uso dos dados ASTER foi superior ao seu uso na resolução original. Não houve diferenças significativas nos valores de r entre o uso das bandas ou dos IVs para predizer as variáveis biofísicas. Regressões lineares simples se mostraram mais adequadas do que as regressões não lineares (exponenciais e logarítmicas) e múltiplas para estimar as variáveis biofísicas, apresentando erros inferiores aos estabelecidos nas campanhas de inventários tradicionais (α < 5%). Os mapas gerados a partir do sensor ASTER 30m foram mais fidedignos ao retratar a distribuição espacial destas variáveis na área de estudo devido à alta correspondência destes com os valores observados no inventário (PELD). Assim, a equação de regressão de carbono florestal a partir do ASTER foi usada na criação do projeto REDD+. A estimativa de biomassa e de carbono florestal da FOM mediante uso de dados de sensores ópticos foi adequada, com possibilidades de ser expandida para extensas áreas. A metodologia, portanto, se mostrou apropriada para ao monitoramento, relatório e verificação de estoques de carbono em florestas. / The imprecision of the estimates of carbon stock in natural forests in the global carbon cycle has created a demand for development and standardization of indirect methods for modeling this cycle and CO2 emissions from land use change and forestry. The work had as objective to establish empirical relationships between biomass and carbon stock of an Araucaria Forest (FOM) and medium spatial resolution remote sensing data (ASTER, and LiSSIII TM) through regression analysis. In addition, we created a hypothetical scenario of Reducing Emissions from Deforestation and Forest Degradation and Enhanced Carbon Stocks (REDD+). The study was developed at the Experimental Station of São João do Triunfo, state of Paraná. The regression analysis involved the forest biomass and forest carbon obtained from continuous forest inventory of the Long Term Ecological Research Program (LTER) as dependent variables (y) and spectral bands and vegetation indices (VIs) as independent variables (x). The statistical analysis comprised correlation analysis (r) between the variables x and y; regression analysis from linear, nonlinear and multiple regressions with the following statistics: R², R²adj, Syx, Syx% and residual dispersion. Furthermore thematic maps were made. Correlations between the biophysical variables and the spectral ASTER data were weak therefore ASTER was scaling up to 30m and 45m. The resolution of 30m, using ASTER data was higher than its use in the original resolution. There were not significant differences in r values between use of bands or VIs to predict the biophysical variables. Linear regressions were more suitable than nonlinear regressions (exponential and logarithmic) and multiple to estimate the biophysical variables, with errors lower than established in traditional inventories campaigns (α <5%). Maps generated from ASTER 30m were more reliable in portraying the spatial distribution of these variables in the study area due to the high correlation of these with the values observed in the inventory (LTER). Thus, the forest carbon equation from ASTER data was used in the creation of REDD+. The estimated biomass and forest carbon by using optical sensors data was adequate, with possibilities to be expanded to large areas. The methodology thus proved suitable for the monitoring, reporting and verification of carbon stocks in forests.

A imprecisão das estimativas de carbono estocado em florestas naturais no ciclo global de carbono vem criando uma demanda de desenvolvimento e padronização de métodos indiretos para modelagem deste ciclo e de emissões de CO2 provenientes de mudanças de uso da terra e florestas. O trabalho teve como objetivo estabelecer as relações empíricas existentes entre a biomassa e o estoque de carbono de uma Floresta Ombrófila Mista (FOM) e os dados ópticos provenientes de sensores remotos de média resolução espacial (ASTER, LiSSIII e TM) por meio de análise de regressão. Além disso, criou-se um cenário hipotético de Redução de Emissões por Desmatamento, Degradação Florestal e Aumento de Estoque de Carbono (REDD+). O estudo foi desenvolvido na Estação Experimental de São João do Triunfo, no estado do Paraná. As equações de regressão envolveram como variáveis dependentes (y): a biomassa e o carbono florestal, obtidos indiretamente do inventário florestal contínuo do Programa de Pesquisas Ecológicas de Longa Duração (PELD), e como variáveis independentes (x) as bandas espectrais e os índices de vegetação (IV). O tratamento estatístico envolveu a análise da matriz de correlação (r) entre as variáveis x e y; a análise de regressão linear simples, não linear e múltipla, com as seguintes estatísticas: R², R²aj., Syx, Syx% e dispersão dos resíduos, Por fim, elaboraram-se mapas temáticos para estas variáveis biofísicas. Como as correlações (r) entre as variáveis biofísicas e espectrais do sensor ASTER (15m) foram baixas, a imagem foi degradada para 30m e 45m. Na resolução de 30m, o uso dos dados ASTER foi superior ao seu uso na resolução original. Não houve diferenças significativas nos valores de r entre o uso das bandas ou dos IVs para predizer as variáveis biofísicas. Regressões lineares simples se mostraram mais adequadas do que as regressões não lineares (exponenciais e logarítmicas) e múltiplas para estimar as variáveis biofísicas, apresentando erros inferiores aos estabelecidos nas campanhas de inventários tradicionais (α < 5%). Os mapas gerados a partir do sensor ASTER 30m foram mais fidedignos ao retratar a distribuição espacial destas variáveis na área de estudo devido à alta correspondência destes com os valores observados no inventário (PELD). Assim, a equação de regressão de carbono florestal a partir do ASTER foi usada na criação do projeto REDD+. A estimativa de biomassa e de carbono florestal da FOM mediante uso de dados de sensores ópticos foi adequada, com possibilidades de ser expandida para extensas áreas. A metodologia, portanto, se mostrou apropriada para ao monitoramento, relatório e verificação de estoques de carbono em florestas. / The imprecision of the estimates of carbon stock in natural forests in the global carbon cycle has created a demand for development and standardization of indirect methods for modeling this cycle and CO2 emissions from land use change and forestry. The work had as objective to establish empirical relationships between biomass and carbon stock of an Araucaria Forest (FOM) and medium spatial resolution remote sensing data (ASTER, and LiSSIII TM) through regression analysis. In addition, we created a hypothetical scenario of Reducing Emissions from Deforestation and Forest Degradation and Enhanced Carbon Stocks (REDD+). The study was developed at the Experimental Station of São João do Triunfo, state of Paraná. The regression analysis involved the forest biomass and forest carbon obtained from continuous forest inventory of the Long Term Ecological Research Program (LTER) as dependent variables (y) and spectral bands and vegetation indices (VIs) as independent variables (x). The statistical analysis comprised correlation analysis (r) between the variables x and y; regression analysis from linear, nonlinear and multiple regressions with the following statistics: R², R²adj, Syx, Syx% and residual dispersion. Furthermore thematic maps were made. Correlations between the biophysical variables and the spectral ASTER data were weak therefore ASTER was scaling up to 30m and 45m. The resolution of 30m, using ASTER data was higher than its use in the original resolution. There were not significant differences in r values between use of bands or VIs to predict the biophysical variables. Linear regressions were more suitable than nonlinear regressions (exponential and logarithmic) and multiple to estimate the biophysical variables, with errors lower than established in traditional inventories campaigns (α <5%). Maps generated from ASTER 30m were more reliable in portraying the spatial distribution of these variables in the study area due to the high correlation of these with the values observed in the inventory (LTER). Thus, the forest carbon equation from ASTER data was used in the creation of REDD+. The estimated biomass and forest carbon by using optical sensors data was adequate, with possibilities to be expanded to large areas. The methodology thus proved suitable for the monitoring, reporting and verification of carbon stocks in forests.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The ecodynamics analysis of coastal dunes of Sergipe determined the role and the interactive effect of the anthropic action and of the natural dynamics in the occured fast ambient changes in two sample units of the Northern and Southern Coastline from Sergipe. The present research searched the detailing of the existing ambient dynamics in the fields of the dunes of Pirambu (Northern portion) and Estância (Southern portion) by means of the structural and functional aspects with prominence to the conditioning expressive of dunar vulnerability. The knowledge of the conditions of balance of the systems of the dunes based on the Tricart s Ecodynamics principle demanded the deepening of the relations between geomorphological, fitogeographics, climatological and anthropical the components of the systems of dunes. The use of this integrator perspective found for the Northern Coastline (Biolological Reserve of Santa Isabel) a scenery with dune stability predominance explained by the low threat of system degradation, lack of obstacles to the transgression of the frontal dunes and low human interference. However, the current situation of stable environment may suffer anthropogenic derivations generating a growing tendency to ecodynamical intergrade, covering a longer cycle of environmental changes in levels of vulnerability assessed. The dunes of the Southern Coast include such features with predominance of the morphogenesis upon the pedogenesis. In terms of its ecodynamical assessment, they appear as unstable environments and environments intergrade, but with tendency to a progressive instability. Such dune situation in degradation is explained by the increasing process of disordered occupation, for the expansion of the land divisions and touristic enterprises, beyond the nonexistent of measures of protection that glimpse the containment of processes as illegally carried through dune dismountings. / A análise ecodinâmica das dunas costeiras de Sergipe partiu da verificação do papel e dos efeitos interativos da ação antrópica e da dinâmica costeira nas mudanças ambientais rápidas ocorridas em duas unidades amostrais do Litoral Norte e do Litoral Sul sergipano. A presente pesquisa buscou o detalhamento da dinâmica ambiental existente nos campos dunares de Pirambu (porção Norte) e Estância (porção Sul) mediante os aspectos estrutural e funcional com destaque aos condicionantes mais expressivos de vulnerabilidade dunar. O conhecimento das condições de equilíbrio dos sistemas dunares baseado no princípio ecodinâmico de Tricart demandou o aprofundamento das relações entre as componentes geomorfológicas, fitogeográficas, climáticas e antrópicas dos sistemas dunares. A utilização da perspectiva integradora da paisagem encontrou para o Litoral Norte (Reserva Biológica de Santa Isabel) um cenário com predominância da estabilidade dunar explicado pela pouca ameaça de degradação ao sistema, inexistência de obstáculos à transgressão das dunas frontais e baixa interferência antrópica. Todavia, a atual situação de meio estável pode sofrer derivações antropogênicas geradoras de uma crescente tendência ecodinâmica ao intergrade, abrangendo um ciclo mais longo de mudanças ambientais nos patamares de vulnerabilidade aferidos. Nas dunas do Litoral Sul predomina a morfogênese sobre a pedogênese. Em termos de sua avaliação ecodinâmica, apresentam-se como meios instáveis e meios em intergrade, mas com tendência a uma progressiva instabilidade. Tal situação de dunas em arrasamento é explicada pelo crescente processo de ocupação desordenada, pela expansão dos loteamentos e empreendimentos turísticos, além da inexistência de medidas de proteção que vislumbrem a contenção de processos como desmontes de dunas realizados ilegalmente.

Submitted by Jaqueline Silva (jtas29@gmail.com) on 2016-10-18T17:49:47Z No. of bitstreams: 2 Dissertação - Arthur Vieira de Santana - 2016.pdf: 3168348 bytes, checksum: ec141ec87784116d724a6eb2f62a872e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-10-18T17:50:03Z (GMT) No. of bitstreams: 2 Dissertação - Arthur Vieira de Santana - 2016.pdf: 3168348 bytes, checksum: ec141ec87784116d724a6eb2f62a872e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-10-18T17:50:03Z (GMT). No. of bitstreams: 2 Dissertação - Arthur Vieira de Santana - 2016.pdf: 3168348 bytes, checksum: ec141ec87784116d724a6eb2f62a872e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-09-22 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The common bean (Phaseolus vulgaris L.) is a main component of Brazilian population diet, and is among of the four most economically important annual crop in Brazil. Given the social and economic importance of the bean, the development of methods to enable the condition monitoring of plants is necessary. In this context arises the remote sensing, in which the interaction of the electromagnetic spectrum with vegetables results in absorption, reflection or transmission of energy. For remote sensing the reflected energy is the main object of study. The energy after interaction is reflected in different wavelengths, which combinations give rise to the vegetation index. There are several vegetation index obtained from remote sensing, among them one of the most used is the normalized difference vegetation index (NDVI). Remote sensing has become an important tool for researchers, mainly to government action, since it identifies and monitor crops, harvest time, make projections and supervise the environment. According to the above, the objective of this study was to evaluate the efficiency of the NDVI vegetation index in determining leaf area index, total dry biomass, stem dry matter and leaf dry matter of four common bean genotypes. The experiment was conducted in the field, at the National Rice and Beans Research Center of Brazilian Agricultural Research Corporation (EMBRAPA), located in Santo Antônio of Goiás. Was used the randomized block design in a 24 factorial design, two sowing dates and four genotypes, in four replications. Sowing dates were 05.17.2013 and 07.03.2013. The genotypes used were: BRS Pérola, Bat 477, BRS Pontal and BRS Agreste. Obtaining the NDVI occurred with radiometric sensor field. The leaf area index (LAI), total dry matter (TDM), stem dry matter (SDM) and leaf dry matter (LDM) were determined with the collection of five plants per meter, which separated the stems and leaves. The leaf area was measured with a photoelectric integrator. According to the results it was observed that at 40 days after emergence NDVI were saturated for two sowing dates. The LAI, the TDM, SDM and LDM for each genotype, were well estimated from NDVI. The root mean square error (RMSE) and the mean absolute error (MAE) were more suitable for assessing the quality of the models within the same biophysical parameters. Despite the genotype and sowing date have affected the adjustment of models, it is possible to estimate the biophysical characteristics from bean with a linear generic model. Among the culture biophysical indicators the SDM was the best parameter estimated overall model and the LDM was the worst. / O feijão-comum (Phaseolus vulgaris L.) é um dos principais componentes da dieta da população brasileira e está entre as quatro culturas economicamente importantes no Brasil, dentre as culturas anuais. Dada à importância social e econômica do feijoeiro, é necessário o desenvolvimento de métodos que possibilitem o monitoramento das condições das plantas. Nesse contexto surge o sensoriamento remoto, no qual a interação do espectro eletromagnético com os vegetais resulta em absorção, reflexão ou transmissão da energia. Para o sensoriamento remoto a energia refletida é o principal objeto de estudo. A energia após interação é refletida em diversos comprimentos de onda, cujas combinações dão origem aos índices de vegetação. Diversos são os índices de vegetação obtidos a partir do sensoriamento remoto, dentre eles um dos mais utilizados é o índice de vegetação por diferença normalizada (NDVI, normalized difference vegetation index). O sensoriamento remoto tem se tornado uma importante ferramenta para pesquisadores e, principalmente, para ações governamentais, pois permite identificar e monitorar culturas, realizar acompanhamento das safras, fazer projeções e fiscalizar o uso do ambiente. De acordo com o exposto, o objetivo deste trabalho foi avaliar a eficiência do índice de vegetação NDVI na determinação da área foliar, matéria seca total de plantas, matéria seca de colmo e matéria seca de folha de quatro genótipos de feijão-comum. O experimento foi conduzido em campo, no Centro Nacional de Pesquisa da Embrapa Arroz e Feijão, fazenda Capivara, localizado no município de Santo Antônio de Goiás. Utilizou-se o delineamento experimental de blocos ao acaso em esquema fatorial 2x4, duas datas de semeadura e quatro genótipos. Utilizaram-se quatro repetições. As datas de semeadura foram 17/05/2013 e 03/07/2013. Os genótipos utilizados foram: BRS Pérola, Bat 477, BRS Pontal e BRS Agreste. A obtenção do NDVI ocorreu com sensor radiométrico de campo. A determinação do índice de área foliar (IAF), matéria seca total de plantas (MST), matéria seca do colmo (MSC) e matéria seca de folha (MSF) foi realizada com a coleta de cinco plantas por metro, das quais se separou os caules e folhas. Para a determinação da área foliar utilizou-se um integrador de área foliar fotoelétrico. De acordo com os resultados foi possível observar que aos 40 dias após a emergência o NDVI apresentou saturação para as duas datas de semeadura. O IAF, a MST, a MSC e a MSF, para cada genótipo, foram bem estimadas a partir do NDVI. A raiz do erro quadrático médio (RMSE) e o erro absoluto médio (MAE) se mostraram mais satisfatórios para a avaliação da qualidade dos modelos dentro dos mesmos parâmetros biofísicos. Apesar dos fatores genótipos e data de semeadura terem afetado os ajustes dos modelos, é possível estimar os parâmetros biofísicos da cultura do feijoeiro utilizando-se um modelo genérico. Entre os indicadores biofísicos da cultura a MSC foi o melhor parâmetro estimado no modelo geral e a MSF foi o pior.

Submitted by Neusa Fagundes (neusa.fagundes@unioeste.br) on 2017-09-18T12:59:07Z No. of bitstreams: 1 Victor_Prudente2017.pdf: 2943373 bytes, checksum: 9bc7b35805d7987e01d85665f9ba8802 (MD5) / Made available in DSpace on 2017-09-18T12:59:07Z (GMT). No. of bitstreams: 1 Victor_Prudente2017.pdf: 2943373 bytes, checksum: 9bc7b35805d7987e01d85665f9ba8802 (MD5) Previous issue date: 2017-02-09 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The spatio-temporal dynamics of agricultural crops can be monitored through Vegetation Indices (VI) on multiple dates. The use of IV in a given period of crop development or throughout its cycle, has generated good relations with agronomic parameters. There are several IV, the NDVI (Normalized Difference Vegetation Index) being one of the most used. NDVI correlates with some agronomic variables such as plant height, leaf area index (LAI), dry matter, chlorophyll index (CI), soil cover degree, plant height and photosynthetically active intercepted radiation (PAIR). Hence, the objective of this work is to compare and intercalibrate NDVI spectral-temporal profiles obtained by different terrestrial remote Sensors, and to use these profiles to estimate biophysical parameters (LAI, CI, PAIR, and Plant Height) for soybean and bean, in addition to estimating and studying soybean yield through models with spectral-temporal data obtained by different terrestrial remote sensors. The ground sensors used are the GreenSeeker 505 Handheld active sensor and the passive hyperspectral FieldSpec4 Standard-Res model. The NDVI values of the passive (NDVI FS) and active (NDVI GS) sensors presented high correlation (soybean rs = 0.90 and bean rs = 0.93) and the linear models respond well to an intercalibration considering the entire phenological cycle of soybean (R² = 0.83, RMSE = 0.0161 e dr = 0.85) and beans (R² = 0.92, RMSE = 0.0038 e dr = 0.89). The saturation of the NDVI values at the survey dates that are located during the vegetative peak of the crops and the presence of adverse climatic events decreased the precision of the models in certain periods of the phenological cycle of the crops. The variables LAI and Height for both crops and CI for the soybean crop obtained better results when estimated by the values of NDVI GS. PAIR for both crops and CI for bean obtained better adjustments considering the models using NDVI FS values. For the variable productivity, there was no significant correlation with the NDVI GS and NDVI FS. However, it presented relations with the accumulation of reflectance observed in the RED and NIR bands for both sensors as a result of different collection dates. The best relations of productivity were with the accumulation of reflectance values of the spectroradiometer bands on DAS76 and DAS71 dates. / A dinâmica espaço-temporal das culturas agrícolas pode ser monitorada por meio de Índices de Vegetação (IV) em múltiplas datas. A utilização do IV, em um determinado período do desenvolvimento das culturas, ou, ainda, em todo o seu ciclo, possui boas relações com parâmetros agronômicos. Há diversos IVs, sendo o NDVI (Normalized Difference Vegetation Index) um dos mais utilizados. O NDVI possui relação com algumas variáveis agronômicas como altura de planta, Índice de Área Foliar (IAF), matéria seca, índice de clorofila (IC), grau de cobertura do solo, altura de planta e radiação fotossinteticamente ativa interceptada (RFAI). Neste sentido, o objetivo deste trabalho foi comparar perfis espectro-temporais NDVI obtidos por diferentes sensores remotos terrestres, e utilizar esses perfis para estimar parâmetros biofísicos (IAF, IC, RFAI e altura de planta) para a soja e o feijão, além de estimar/estudar a produtividade da soja por meio de modelos com dados espectro-temporais obtidos por diferentes sensores remotos terrestres. Utilizou-se o sensor ativo GreenSeeker 505 Handheld e o sensor passivo hiperespectral FieldSpec4 modelo Standard-Res. Os valores de NDVI dos sensores passivos (NDVI FS) e ativos (NDVI GS) apresentaram alta correlação (soja rs = 0,90 e feijão rs = 0,93), e os modelos lineares respondem bem a um ajuste, ao se considerar todo o ciclo fenológico da soja (R² = 0,83, RMSE = 0,0161 e dr = 0,85) e feijão (R² = 0,92, RMSE = 0,0038 e dr = 0,89). A saturação dos valores de NDVIs nas datas de levantamento que se situam durante o pico vegetativo das culturas e a presença de eventos climáticos adverso diminuíram a precisão dos modelos em determinados períodos do ciclo fenológico das culturas. As variáveis IAF e altura para a soja e o feijão e IC para a soja obtiveram melhores resultados ao ser estimadas por meio dos valores de NDVI GS. RFAI para ambas as culturas e IC para o feijão obtiveram melhores ajustes por meio dos modelos que se utilizavam de valores de NDVI FS. Para a produtividade, não houve correlação significativa com os NDVI GS e NDVI FS. Entretanto, apresentou relações com o acúmulo de refletância observados nas bandas RED e NIR para ambos os sensores em diferentes datas de coleta. As melhores relações da produtividade foram com o acúmulo de refletância das bandas do espectroradiômetro nas datas DAS76 e DAS71.

Acacia senegal and Acacia seyal are important agroforestry cash crops indigenous to several countries of sub-Saharan Africa, including Nigeria. The gum exudate produced by these species is termed gum Arabic which is an approved food additive (E414), primarily used as an emulsifier. In the current study, the molecular structure, composition and biophysical properties of gum samples harvested from mature trees of Acacia senegal at two specific ecolocations in Nigeria (NG1 and NG2), have been investigated together with two previously characterised gum samples harvested from A. senegal and A. seyal originating from Sudan. The monosaccharide sugar composition analyses have shown that the A. seyal gum had a lower rhamnose and glucuronic acid content than the A. senegal gum, but had higher arabinose content. No significant difference was observed between the sugar composition of the A. senegal gums from Sudan and Nigeria. The total protein content of the Nigerian gum samples were significantly higher than recorded for the Sudanese samples. The principal amino acids present in all the gum samples are hydroxyproline, serine, aspartame, threonine and proline which is in agreement with literature values. The hydrodynamic size of the molecules present in the gums was studied using dynamic light scattering and it was found that molecular association occurred in solution over time which was inhibited in the presence of an electrolyte. The comparison of droplet size distribution for emulsions prepared with A. senegal (NG1) and A. seyal gum samples showed that A. senegal sample was a better emulsifier than the A. seyal. Multilayer adsorption of the samples onto polystyrene latex particles was observed, which resulted in an increase in thickness of the adsorbed layer as a consequence of the interaction between the protein and carbohydrate within the molecules adsorbed on the emulsion surface. Preliminary analyses of the gums using transmission electron microscopy showed the presence of varied macromolecules, ranging in size from ~12 - ~60 nm. Immuno-gold negative staining (using JIM8 monoclonal antibody) indicated clear labelling of arabinogalactan-proteins present in the gums harvested from A. senegal, the labelling of the A. seyal sample was inconclusive. In summary, the data presented represents the first detailed comparison of the structure, composition and physicochemical characteristics of Nigerian Acacia gum exudates versus Sudanese samples (main global supplier) which have shown that gum obtained from Nigerian sources is a viable alternative to ensure future supply of this valuable natural resource.

This dissertation explores the fusion of the built and biophysical environments within the context of the city. In doing so the biophysical environment contributes to the operation of the architecture in terms of microclimate control, containment, form and aesthetic. The building houses the programme of an Ethnobotanic Research Centre [EBRC], which serves as a place of research into the medicinal properties of indigenous plants and propagation thereof. The building also becomes a point of intervention to prevent the encroachment of the city on the greenbelts of Pretoria. / Dissertation (MArch (Prof))--University of Pretoria, 2005. / Architecture / unrestricted

Heme proteins carry out a diverse array of functions in vivo while maintaining a well-conserved 3-over-3 α-helical structure. Human hemoglobin (Hb) is well-known for its oxygen transport function. Type 1 non-symbiotic hemoglobins (nsHb1) in plants and bacterial flavohemoglobins (fHb) from a variety of bacterial species have been predicted to carry out a nitric oxide dioxygenase function. In nsHb1 and fHb this function has been linked to protection from nitrosative stress. Herein, I combine photoacoustic calorimetry (PAC), transient absorption spectroscopy (TA), and classical molecular dynamics (cMD) simulations to characterize molecular mechanism of diatomic ligand interactions with a hexa-coordinate globin from plant (rice hemoglobin), bacterial flavohemoglobins and human hemoglobin. In rice type 1 non-symbiotic hemoglobin (rHb1), the dynamics and energetics of structural changes associated with ligand photodissociation is strongly impacted by solvent and temperature, namely CO escape from the protein matrix is slower at pH = 6.0 compare to neutral pH (ns) due to the CD loop reorganization which forms a pathway for ligand escape. In human hemoglobin, exogenous allosteric effectors modulate energetics of conformational changes associated with the CO and O2 escape although the effectors impact on rate constants for ligand association is small. The conformational dynamics associated with ligand photorelease from fHbs from Cupriavidus necator (FHP) and Staphylococcus aureus (HMPSa) are strongly modulated by the presence of azole drugs indicating that drug association modulates structural properties of the heme binding pocket. In addition, we carried out a study of the formation of the DNA intercalated motif (i-motif). The formation of the structure is strongly favored at acidic pH; therefore, PAC was combined with a 2-nitrobenzaldehyde pH-jump to probe formation of the i-motif on fast timescales. i-Motif folding is two-step process with the initial protonation of cytosine residues being endothermic with ΔHfast=8.5 ± 7.0 kcal mol-1 and ΔVfast=10.4 ± 1.6 mL mol-1 and subsequent nucleation/i-motif folding (τ = 140 ns) with ΔHslow=-51.5 ± 4.8 kcal mol-1 and ΔVslow=-6.6 ± 0.9 mL mol-1. The above results indicate that PAC can be employed to study diverse biochemical reactions such as DNA folding, drug binding and ligand photorelease from proteins.

Les récepteurs de type kaïnate (rKA) appartiennent, avec les récepteurs de type NMDA (rNMDA) et les recepteurs de type AMPA (rAMPA), à la famille des récepteurs canaux glutamatergiques (iGluR). Les propriétés fonctionelles des rKA contenant la sous-unité GluK3 en font des récepteurs tout à fait singuliers. Une étude réalisée dans le laboratoire a montré que la faible sensibilité de ces récepteurs au glutamate est liée à une entrée très rapide dans l’état désensibilisé et que la fonction de ces récepteurs pourrait être amplifiée par des modulateurs endogènes.Parmi les modulateurs potentiels de la fonction des rKA pré-synaptiques, nous avons choisi d’étudier le zinc, en raison de sa concentration importante dans les vésicules des terminaisons des axones des cellules granulaires du gyrus denté (fibres moussues). En dépit du rôle proposé des rKA contenant la sous unité GluK3 dans la régulation pré-synaptique aux synapses MF-CA3, la modulation de ces récepteurs par le zinc n’a jamais été étudiée.Grâce à l’enregistrement électrophysiologique des courants GluK3 exprimés dans les cellules HEK-293, nous avons montré que le zinc facilite les courants des récepteurs contenant la sous-unité GluK3, activés par le glutamate. L’analyse des cinétiques, ainsi que la modélisation, montrent que l’effet facilitateur du zinc est dû à la réduction de l’entrée dans l’état désensibilisé des récepteurs GluK3. Grâce à la mutagénèse dirigée et l’étude cristallographique, nous avons pu déterminer le site de liaison du zinc, constitué de l’aspartate 759, de l’histidine 762 et de l’aspartate 730, et localisé dans l’interface de dimérisation du domaine de liaison de l’agoniste (LBD).Cette étude décrit pour la première fois un nouveau site de modulation positive de la fonction des rKA. / Glutamate released at excitatory synapses acts on ligand-gated ionotropic receptors which fall into three classes: NMDA, AMPA and kainate receptors.At hippocampal mossy fiber synapses onto CA3 pyramidal cells, KARs are present both at the pre- and postsynaptic levels. Postsynaptic KARs are composed of the GluK2, GluK4 and GluK5 subunits, whereas presynaptic KARs are thought to comprise the GluK2 and GluK3 subunits. The functional properties of GluK3 (and GluK2/GluK3) receptors set it apart from the other ionotropic glutamate receptors. In particular, its sensitivity to glutamate is the lowest of all known ionotropic glutamate receptors, due in large part to fast desensitization of receptors with one or two bound glutamate molecules. The low agonist sensitivity of this receptor raises questions about its relevance for synaptic function. Therefore, it is possible that endogenous modulators may potentiate its function.Among potential endogenous modulators of KAR function, we chose to address the role of zinc, because of the large amounts contained in mossy fiber terminals. Zinc is thought to be accumulated into synaptic vesicles, and is co-released with glutamate in the extracellular milieu during neuronal activity. Zinc has been reported to inhibit most of native and recombinant KARs. Despite the proposed role of at hippocampal mossy fiber synapses, although modulation of GluK3-containing KARs by zinc has not yet been addressed.In this study, we show that zinc greatly potentiates recombinant GluK3 receptor currents evoked by glutamate. Zinc markedly slows receptor desensitization and increases apparent affinity for glutamate. Crystallographic studies and analysis of chimeric GluK2/GluK3 KARs and of GluK3 bearing selected point mutations, allowed us to identify the zinc binding domain defined by D759, H762, Q756 and D730, and localized in a region forming the interface between two GluK3 subunits in an LBD dimer assembly. Based on these structure-function studies and on modeling of KAR activity, we show that zinc plays a very distinct role on GluK3-KARs by stabilizing the interaction between dimers of LBD thereby reducing desensitization.Given the proposed localization of GluK3 close to zinc containing synaptic vesicles, zinc may be an endogenous allosteric modulator for native GluK3-KARs, and its binding site a new pharmacological target.

Wildfire hazard is increasing in much of the United States, posing a threat to human communities and natural ecosystem services, especially in areas at the wildland-urban interface. There are steps people can take to reduce wildfire hazard, but often they are not used. Understanding and addressing human perceptions of wildfire risk and of risk-mitigating behaviors requires knowledge of both social and ecological systems. To better understand this complex issue, three types of factors must be addressed: social, cultural, demographic, and biophysical. This dissertation incorporates these three essential factors to intensively investigate the risk perception and behaviors of residents living in wildland-urban interface communities in three states (Arizona, California, and New Mexico). The first study examines the effect that individual risk perceptions have on intention to mitigate wildfire risk by integrating two social-psychological theories, Theory of Planned Behavior and Cultural Theory, to investigate the causal relationship and motivational factors that influence the intention to mitigate wildfire hazard. Results suggest that attitudes toward wildfire mitigation practices and perceived behavioral control play a significant role in the decision process. The effect of an individual’s orientation toward nature is mediated by attitude and perceived behavioral control. It is important that these orientations are taken into consideration when designing strategies to increase incentives to mitigate fire risk. The second study explores the linkage between property owners’ perception of risk and scientifically measurable wildfire risks that vary across hazard zones in the three study locations. Individuals’ perceptions of wildfire can be substantially different from each other and from reality. This study proposes that the perception of risk is formed in a multistage process (individual and community level). Results show that homeowners’ worldview with respect to nature, length of residency, place-based influence, and attitudes about risk factors all are significant predictors for how residents of fire-prone areas perceive their risks. The variance in social and physical vulnerability associated with wildfire can explain, to a certain extent, the variation in individual perceptions of wildfire risk. The perception of risk is consistent with the level of exposure to fire hazards. The third study investigates spatial relationships among social and ecological factors on private property. The biophysical characteristics of individual properties were extracted to observe wildfire risk and incorporated with information about social context from mail surveys. Results demonstrate that mitigation behaviors in the three study communities illustrate a spatial clustering pattern. Moreover, orientations toward nature and physical attributes of property had an impact on decisions to undertake mitigation behaviors.