Die Rasterionenleitfähigkeitsmikroskopie (scanning ion conductance microscopy, SICM) stellt eine kontaktfreie Methode zur Ermittlung sowohl der Topographie als auch lokalen Ionenleitfähigkeit einer Oberfläche dar. Besonders vorteilhaft ist die Vermeidung mechanischer Beeinflussung bei der Untersuchung flexibler Strukturen, z.B. Lipiddoppelschichten wie Zellen oder künstlich erzeugter Lipidmembranen. Porenüberspannende Membranen (pore-suspending membranes, PSMs) verbinden als ein Beispiel für Modellsysteme eine hohe Stabilität mit lateraler Mobilität und dem Vorhandensein wässriger Kompartimente ober- und unterhalb der Doppelschicht, wie sie auch in der Natur gefunden werden. Ein wichtiges Forschungsgebiet stellt die Untersuchung der Wechselwirkung von Peptiden, besonders zellpenetrierenden Peptiden (cell penetrating peptides, CPPs), mit Lipiden und anderen Membranbestandteilen dar. Häufig untersuchte Beispiele sind Melittin, Hauptbestandteil des Giftes der Honigbiene Apis mellifera, sowie Penetratin, dritte Helix der Antennapedia Homöodomäne von Drosophila melanogaster. Generalisierte Protokolle zur Herstellung lösungsmittelfreier PSMs werden vorgestellt. Riesige unilamellare Vesikel (giant unilamellar vesicles, GUVs) unterschiedlicher Lipidzusammensetzung wurden hierzu auf porösem Siliziumnitrid (Si3N4), welches mit Cholesterylpolyethylenoxythiol (CPEO3, hydrophob) bzw. Mercaptoethanol (ME, hydrophil) funktionalisiert worden war, gespreitet. Verwendet wurden GUVs aus reinen Phosphatidylcholin (PC)-Lipiden sowie aus Mischungen von PC-Lipiden mit Cholesterol und PC-Lipiden mit Phosphatidylserin (PS)-Lipiden. Der Erfolg des Spreitvorgangs wurde durch Abbilden mittels konfokaler Rasterlasermikroskopie (confocal laser scanning microscopy, CLSM) und SICM verifiziert. Der Hauptteil dieser Arbeit behandelte die Entwicklung und Anwendung CLSM- und SICM-basierter CPP-Titrationsassays zur Aufklärung des Einflusses der Substratfunktionalisierung und der Lipidzusammensetzung der Membranen auf die Wechselwirkung zwischen Melittin bzw. Penetratin und den Lipiddoppelschichten. CLSM-Experimente wurden mit Melittin auf allen zur Verfügung stehenden PSMs sowohl auf hydrophob als auch hydrophil funktiona-lisierten Substraten durchgeführt, während Penetratin auf den drei unterschiedlichen PSMs auf hydrophil funktionalisierten Substraten verwendet wurde. Ein Reißen der Membranen wurde im Fall hydrophil funktionalisierter Substrate für beide Peptide im Bereich von 1–3 µM beobachtet. Bei hydrophob funktionalisierten Substraten induzierte eine dreifach geringere Melittinkonzentration die Zerstörung der Membranen. Sowohl auf hydrophob als auch auf hydrophil funktionalisierten Substraten wurde bei einem Cholesterolanteil von 10% eine Erhöhung der zum Reißen notwendigen Melittinkonzentratin erhalten, während bei 20% PS-Anteil eine Verschiebung zu geringeren Konzentrationen evident wurde. SICM-Experimente wurden mit Melittin auf PC/Cholesterol-PSMs auf hydrophob und hydrophil funktionalisierten Substraten und mit reinen PC-PSMs auf hydrophil funktionalisierten Membranen durchgeführt. Es wurden keine signifikanten Konzentrationsunterschiede beobachtet; die gefundenen Konzentrationsbereiche jedoch stimmten mit denen der CLSM-Experimente überein. Darüberhinaus wurde vor dem Reißen der Membranen ein Ansteigen der Porentiefe gefunden, das mit einer erhöhten Membranpermeabilität korrespondiert.

In this thesis, several aspects of GPR data processing for RC bridge decks are studied. First, autofocusing techniques are proposed to replace the previous expensive and unreliable human visual inspections during the iterative migration process for the estimation of the velocity/dielectric permittivity distribution from GPR data. Second, F-K filtering with dip relaxation is proposed for interference removal that is important for both imaging and the performance of post-processing techniques including autofocusing techniques and CS-based migration studied in this thesis. The targeted interferes here are direct waves and cross rebar reflections. The introduced dip relaxation is for accommodating surface roughness and medium inhomogeneity. Third, the newly developed CS-based migration is modified and evaluated on GPR data from RC bridge decks. A more accurate model by accounting for impulse waveform distortion that leads to less modeling errors is proposed. The impact of the selection of the regularization parameter on the comparative amplitude reservation and the imaging performance is also investigated, and an approach to preserve the comparative amplitude information while still maintaining a clear image is proposed. Moreover, the potential of initially sampling the time-spatial data with uniform sampling rates lower than that required by traditional migration methods is evaluated.

The problem of subsurface imaging with Ground Penetrating Radar (GPR) is a challenging one. Due to the low-pass nature of soil sensors must utilise wave-lengths that are of the same order of magnitude as the object being imaged. This makes imaging difficult as straight ray approximations commonly used in higher frequency applications cannot be used. The problem becomes even more challenging when the target is shallowly buried as in this case the ground surface reflection and the near-field parameters of the radar need to be considered. This thesis has investigated the problem of imaging shallowly buried targets with GPR. Two distinct problems exist in this field radar design and the design of inverse scattering techniques. This thesis focuses on the design of inverse scattering techniques capable of taking the electric field measurements from the receiver and providing accurate images of the scatterer in real time. The thesis commences with a brief introduction to GPR theory. It then provides an extensive review of linear inverse scattering techniques applied to raw GPR data. As a result of this review the thesis draws the conclusion that, due to its strong foundations in Maxwell's equations, diffraction tomography is the most appropriate approach for imaging shallowly buried targets with GPR. A three-dimensional diffraction tomographic technique is then developed. This algorithm forms the primary contribution of the thesis. The novel diffraction tomography technique improves on its predecessors by catering for shallowly buried targets, significant antenna heights and evanescent waves. This is also the first diffraction tomography technique to be derived for a range of antenna structures. The advantages of the novel technique are demonstrated first mathematically then on synthetic and finally practical data. The algorithm is shown to be of high practical value by producing accurate images of buried targets in real time.

Low-lying coastal plains comprised of unconsolidated infill are internally complex hydrogeological settings, due to the high level of heterogeneity in the infill material. In order to resolve the hydrogeological processes active in these complex settings, an integrated multi-disciplinary, geoscientific approach is required. This research determines quantitatively, the effects of sedimentary aquifer heterogeneity on groundwater flowpaths and groundwater processes within a heavily laterised, coastal plain setting. The study site is the Bells Creek catchment in southeast Queensland, Australia. The methodology developed in this study provides a new approach to enable the determination of groundwater flowpaths and groundwater processes at macroscale resolution within other shallow alluvial and coastal plain aquifers. The multi-disciplinary approach utilises sedimentological, geophysical, chronological and hydrogeological techniques (including hydrochemistry and groundwater flow modelling) to develop a high-resolution aquifer framework, and to determine accurately, both groundwater flowpaths and relative flow rates. Sedimentary framework is confirmed to be the principal factor controlling the distribution of aquifer permeability pathways in any given setting, and is therefore, the dominant control over groundwater flow and processes. For the Bells Creek catchment, interpretation of stratigraphic and sedimentary data allowed the compilation of a detailed sedimentary framework. This interpretation demonstrated that weathering of the low-lying arkose sandstone bedrock has developed thick lateritic profiles. Within the weathering profiles, cemented, iron-rich horizons have resisted erosion and developed raised and elongated ridges in the modern landscape, while other clay-rich weathered layers have submitted to erosion and downgraded around those iron-rich ridges. Consequently, alluvial deposition throughout the Late Quaternary has been restricted to narrow, and relatively deep valleys containing sandrich channels, and thin floodplains at shallow depth. From a hydrogeological perspective, there is significant macroscopic aquifer heterogeneity between fine-grained lateritic mixed clay layers, floodplain clays, ironcemented ferricrete horizons, and permeable sand-rich alluvial aquifers. This variability of aquifer material has created a complex subsurface arrangement of permeability pathways. Application of Ground Penetrating Radar (GPR) in this setting enabled accurate definition of alluvial channel boundaries and the high degree of connectedness within the channels themselves. Interpretation of a comprehensive GPR dataset (that covered the entire catchment) allowed refinement of the sedimentary framework previously established to develop a detailed threedimensional aquifer framework. Finite-difference groundwater modelling and particle tracking analysis (using MODFLOW and MODPATH) has clearly demonstrated that the macroscopic heterogeneity within the various aquifer materials of the plain has marked impacts on groundwater pathways, and especially groundwater travel times. The variability between a maximum residence time of 18 months for groundwater within the alluvium, compared to hundreds of years for groundwater within the mixed clay layers of the laterite, clearly demonstrates the importance of accurately defining the spatial distribution of the various aquifer materials in a groundwater flow investigation. In this setting, the interconnection of the narrow alluvial channels feeding into a deeper alluvial delta has provided an effective conduit for shallow groundwater flow. The role of the alluvial delta in discharging the bulk of fresh groundwater from the central plain into the coastal and estuarine aquifers to the east, is certainly critical in preventing saline intrusion from encroaching further west. Hydrochemical and isotopic indicators have identified the dominant recharge processes and groundwater flowpaths within the plain, and indicated that the processes are strongly related to sub-surface permeability distributions determined in the aquifer framework (and groundwater modelling), as well as seasonal fluctuations in rainfall. In the northwest of the plain, sandstone hills provide a delayed and slightly mineralized component of groundwater recharge into adjacent highly permeable, unconfined alluvial aquifers; these aquifers also recharge directly via precipitation. Aluminosilicate weathering in the bedrock hills and eastern peripheries of the laterised bedrock are a source of excess Na, SiO2, and HCO3 to the alluvial groundwater. As this groundwater flows down-gradient to the east, however, its chemical composition evolves by sulfate reduction, silica equilibrium and ion exchange processes into a more mature Na-Cl type. Within the shallow coastal aquifers proximal to the eastern shoreline, sulfate enrichment is occurring (associated with increases in Ca, HCO3, Fe and Al) resulting in major deterioration in groundwater quality. The deterioration is produced by saline intrusion from the adjacent estuary coupled with oxidation of sulfide materials in shallow marine and estuarine clays. Reverses in salinity in those coastal aquifers have been correlated with surges in fresh recharge waters from unconfined coastal dunes and semi-confined landward alluvium, following significant rainfall events. The multi-disciplinary methodology developed, provides an effective approach for accurately defining the three-dimensional distribution of shallow aquifer material of varying permeability via detailed stratigraphic interpretation and GPR analysis. Utilising this aquifer framework, finite-difference groundwater modelling aided by hydrogeological data and hydrochemical analysis, allows accurate determination of groundwater flowpaths and groundwater processes. This research provides a new hydrogeological analogue for alluvial channel aquifers within a laterised coastal plain setting. Key Words: groundwater flow, aquifer heterogeneity, numerical modelling, hydrochemistry, recharge, ground penetrating radar, coastal plain aquifers, weathering, alluvial channels.

The inflammatory arthritis Ankylosing Spondylitis (AS) is linked to the human leucocyte antigen HLA-B27. HLA-B27 is thought to drive AS because it misfolds during assembly in the endoplasmic reticulum (ER), inducing ER cell stress. Modulating HLA-B27 folding in the ER is therefore a therapeutic target pathway. The recent discovery of polymorphisms in the ER-resident peptidase ERAP1 that can impact on HLA-B27 and AS, makes ERAP1 one such target. Exosomes are small, typically 50-200 nm sized particles, formed in the endosomal recycling pathway, which can be released into the extracellular environment. Exosomes have a wide range of biological activities depending on the cell type of origin, and on the delivered cargo, which can include bio-active proteins, lipids, mRNA and miRNA. There is interest in the use of exosomes as drug delivery agents. Here, exosomes were studied as a delivery agent to modulate ERAP1, as a potential therapeutic tool for the treatment of AS. Exosomes, isolated from cell lines including CEM and Jurkat (T cell lineage), Jesthom (B cell lineage), U937 (monocyte lineage) and the epithelial HeLa cell line, were characterized by nanoparticle tracking analysis, flow cytometry and immunoblotting using markers including CD9, CD63, CD81 and TSG101. Differential expression of these markers in the immune cell lines indicated the complexity of defining exosomes. EVs were then tested using cell penetrating peptides, electroporation, lipid transfection and sonication for their ability to load FITC-siRNA or FITC-antibody as cargo. Significantly, post-loading RNase A or trypsin incubation demonstrated that many techniques do not lead to efficient cargo loading of exosomes. Sonication proved the most effective technique, with up to 30% efficiency. Loading of exosomes with ERAP1-targetted siRNA did not however lead to notable ERAP1 inhibition. The data indicates that external loading of exosomes with cargo remains a significant challenge in developing exosomes as therapeutic tools.

[pt] O presente trabalho tem por objetivo avaliar as potencialidades do método GPR (Ground Penetrating Radar) em investigações de campo que englobam estudos hidrogeológicos, geotécnicos e ambientais. Para o alcance deste objetivo foram realizadas investigações de campo na região sudeste do Brasil procurando verificar a aplicabilidade deste método no conhecimento da subsuperfície. Os estudos englobaram a determinação da estratigrafia do solo identificando suas camadas e respectivas profundidades; a determinação da posição do lençol freático; a localização de estruturas enterradas e a detecção de possíveis anomalias decorrentes de contaminações. As seções obtidas com o GPR permitiram identificar com boa resolução os contrastes bruscos, como a posição do lençol freático e a localização das estruturas enterradas. A identificação dos contatos entre as camadas de solo foi possível quando as propriedades elétricas destes materiais se diferiam bastante. Já no que diz respeito ao mapeamento de regiões contaminadas, ainda se faz necessário à realização de uma maior quantidade de estudos para afirmar a eficiência do GPR para este objetivo. A utilização da técnica da reflectometria no domínio do tempo (TDR) foi muito útil para correlacionar a velocidade de propagação das ondas eletromagnéticas com a profundidade. O seu emprego permitiu aumentar a exatidão da determinação das profundidades dos alvos de interesse. / [en] The present work aims to assess the adequacy of the ground penetrating radar as a screening tool in site in site investigation practice in hydrogeological, geotechnical and environmental studies. An extensive site investigation program was carrid out in Southeast Brazil looking for characterizing the subsurface. Tests were performed to determine the statigraphy of soil profiles, the position of the water level, the detection of buried structures and contamination. The results have shown a great deal of success in identifying water levels and buried structures. Soil surface were only identified when abrupt changes in the dielectric constant of the porous media were observed. Howerer, the results so far do not enable to delineate contamination plumes with the accuracy desired. The accuracy of the target depths were greatly improved by using the result of the dielectric constant measured by the time domain reflectometry (TDR)

Este trabalho trata da simulação da propagação de ondas eletromagnéticas (1-D) em meios geológicos de propriedades físicas conhecidas (espessura, condutividade e permissividade elétrica), do registro das ondas EM refletidas (dados sintéticos) para uma antena receptora, e do uso desse registro em algoritmos de inversão e otimização que procuram estimar as propriedades físicas dos meios geológicos. Adotou-se modelos geológicos estratificados de pequena espessura (< 1,2 m) e altas frequências para a onda eletromagnética (800, 1000 e 1200 MHz). A propagação da onda eletromagnética é modelada por meio da resolução das equações de Maxwell no método FDTD. Os métodos de inversão Quasi-Newton e Otimização Ant Colony modificado são aplicados sobre os dados sintéticos para estimar os parâmetros elétricos para cada camada geológica. Ambos os métodos foram aplicados alternadamente para aumentar a precisão e a convergência ao longo da profundidade. Os métodos de inversão foram capazes de estimar simultaneamente duas propriedades eletromagnéticas do modelo geológico: a permissividade elétrica e a condutividade elétrica. Os métodos de inversão alcançaram bons resultados quando executados simultaneamente sobre os dados sintéticos em 3 diferentes frequências. Exemplos de estimativas dos perfis de condutividade e permissividade elétricas unidimensionais são apresentados, com e sem inserção de ruídos nos dados. Os resultados indicam que a combinação dos métodos de inversão (ACO modificado e Quasi-Newton) pode fornecer bons resultados para as estimativas dos parâmetros físicos de meios geológicos e geotécnicos em meios rasos. Além disso, essa combinação de métodos de inversão abre novas perspectivas para o processamento de dados georradar multi-canais. As investigações também mostram que a simulação dos perfis sintéticos por meio do método FDTD pode propagar erros em espessuras maiores de subsolo, devido ao fato de ser um método explícito. / This work deals with simulation of a 1-D electromagnetic wave propagating into a geological structure of known physical properties (thickness, electric conductivity and permittivity), the record of the reflected EM wave (synthetic data), and the use of these records in inversion and optimization algorithms to estimate back the physical properties of the geological structure. A stratified and thin (< 1.2 m) geological structure was initially constructed in order to be scanned by high frequency EM waves (800, 1000, and 1200 MHz). The EM wave propagation is simulated by Maxwell equations through FDTD method. The Quasi-Newton inversion and Ant Colony Optimization methods were applied into synthetic data to estimate original physical parameters of each geological layer. Both methods were applied in order to increase precision and convergence along depth. These methods were able to simultaneously estimate two physical properties of the geological structure: electrical permittivity and conductivity. The methods showed good results when applied simultaneously upon synthetic data of all three frequencies. Electric permittivity and conductivity profiles are shown with and without noise in the data. The results indicate that combined inversion methods can show good results to estimate physical properties of thin geological and geothecnical structures. The combined inversion methods open new perspectives to multichannel GPR data processing. The investigations also show that simulation of synthetic data through FDTD can propagate errors when dealing with thick geological structures, due to the fact that FDTD is an explicit method.

Este trabalho trata da simulação da propagação de ondas eletromagnéticas (1-D) em meios geológicos de propriedades físicas conhecidas (espessura, condutividade e permissividade elétrica), do registro das ondas EM refletidas (dados sintéticos) para uma antena receptora, e do uso desse registro em algoritmos de inversão e otimização que procuram estimar as propriedades físicas dos meios geológicos. Adotou-se modelos geológicos estratificados de pequena espessura (< 1,2 m) e altas frequências para a onda eletromagnética (800, 1000 e 1200 MHz). A propagação da onda eletromagnética é modelada por meio da resolução das equações de Maxwell no método FDTD. Os métodos de inversão Quasi-Newton e Otimização Ant Colony modificado são aplicados sobre os dados sintéticos para estimar os parâmetros elétricos para cada camada geológica. Ambos os métodos foram aplicados alternadamente para aumentar a precisão e a convergência ao longo da profundidade. Os métodos de inversão foram capazes de estimar simultaneamente duas propriedades eletromagnéticas do modelo geológico: a permissividade elétrica e a condutividade elétrica. Os métodos de inversão alcançaram bons resultados quando executados simultaneamente sobre os dados sintéticos em 3 diferentes frequências. Exemplos de estimativas dos perfis de condutividade e permissividade elétricas unidimensionais são apresentados, com e sem inserção de ruídos nos dados. Os resultados indicam que a combinação dos métodos de inversão (ACO modificado e Quasi-Newton) pode fornecer bons resultados para as estimativas dos parâmetros físicos de meios geológicos e geotécnicos em meios rasos. Além disso, essa combinação de métodos de inversão abre novas perspectivas para o processamento de dados georradar multi-canais. As investigações também mostram que a simulação dos perfis sintéticos por meio do método FDTD pode propagar erros em espessuras maiores de subsolo, devido ao fato de ser um método explícito. / This work deals with simulation of a 1-D electromagnetic wave propagating into a geological structure of known physical properties (thickness, electric conductivity and permittivity), the record of the reflected EM wave (synthetic data), and the use of these records in inversion and optimization algorithms to estimate back the physical properties of the geological structure. A stratified and thin (< 1.2 m) geological structure was initially constructed in order to be scanned by high frequency EM waves (800, 1000, and 1200 MHz). The EM wave propagation is simulated by Maxwell equations through FDTD method. The Quasi-Newton inversion and Ant Colony Optimization methods were applied into synthetic data to estimate original physical parameters of each geological layer. Both methods were applied in order to increase precision and convergence along depth. These methods were able to simultaneously estimate two physical properties of the geological structure: electrical permittivity and conductivity. The methods showed good results when applied simultaneously upon synthetic data of all three frequencies. Electric permittivity and conductivity profiles are shown with and without noise in the data. The results indicate that combined inversion methods can show good results to estimate physical properties of thin geological and geothecnical structures. The combined inversion methods open new perspectives to multichannel GPR data processing. The investigations also show that simulation of synthetic data through FDTD can propagate errors when dealing with thick geological structures, due to the fact that FDTD is an explicit method.

La maurocalcine (MCa) est une toxine de 33 acides aminés initialement issue du venin du scorpionScorpio maurus palmatus, et est considérée comme faisant partie de la famille des CPP(Cell Penetrating Peptides) depuis de nombreuses années déjà. La MCa présente donc un intérêtthérapeutique certain dans le domaine de la délivrance intracellulaire de cargos, et lestravaux exposés ici cherchent à caractériser au mieux les propriétés de pénétration de la moléculenative ainsi que celle de certains de ses variants.Après avoir quantifié l’internalisation de plusieurs variants tronqués (linéaires), j’ai pu mettreen évidence le fait que tous ces analogues testés ont une capacité à être internalisés bien plusélevée que celle des CPP de référence (notamment Tat et la pénétratine). Parmi ces variants,l’analogue MCaUF1−9 présente l’avantage d’un temps de rétention relativement élevé au seindes cellules, ainsi que d’une accumulation légèrement accrue en environnement acide (ce quiadvient lors de la formation tumeurs solides). Ce nouveau CPP possède donc un certain potentielthérapeutique mais l’étude de la MCa native, remarquablement stable in vivo, reste plusque jamais d’actualité. / Maurocalcine (MCa) is a 33-mer toxin originally isolated from the venom of the scorpioScorpio maurus palmatus, and has been considered as a cell-penetrating peptide (CPP) for severalyears. MCa presents a therapeutic interest for the intracellular delivery of cargoes, andthis thesis aims to characterise the cell penetration properties of the native molecule as well assome of its variants’.After quantifying several truncated (linear) variants’ internalisation, I have been able tohighlight the fact that all of those analogs possess a higher internalization ability than those ofstandard CPP (especially Tat and penetratin). Among those variants, the analog MCaUF1−9 hasa relatively high rentention time within cells, as well as a slightly increased accumulation whenin an acidic environment (which occurs during solid tumours formation). This new CPP showsa certain therapeutic potential but the study of nativeMCa, remarkably stable in vivo, remainsa priority.

Este trabalho trata da simulação da propagação de ondas eletromagnéticas (1-D) em meios geológicos de propriedades físicas conhecidas (espessura, condutividade e permissividade elétrica), do registro das ondas EM refletidas (dados sintéticos) para uma antena receptora, e do uso desse registro em algoritmos de inversão e otimização que procuram estimar as propriedades físicas dos meios geológicos. Adotou-se modelos geológicos estratificados de pequena espessura (< 1,2 m) e altas frequências para a onda eletromagnética (800, 1000 e 1200 MHz). A propagação da onda eletromagnética é modelada por meio da resolução das equações de Maxwell no método FDTD. Os métodos de inversão Quasi-Newton e Otimização Ant Colony modificado são aplicados sobre os dados sintéticos para estimar os parâmetros elétricos para cada camada geológica. Ambos os métodos foram aplicados alternadamente para aumentar a precisão e a convergência ao longo da profundidade. Os métodos de inversão foram capazes de estimar simultaneamente duas propriedades eletromagnéticas do modelo geológico: a permissividade elétrica e a condutividade elétrica. Os métodos de inversão alcançaram bons resultados quando executados simultaneamente sobre os dados sintéticos em 3 diferentes frequências. Exemplos de estimativas dos perfis de condutividade e permissividade elétricas unidimensionais são apresentados, com e sem inserção de ruídos nos dados. Os resultados indicam que a combinação dos métodos de inversão (ACO modificado e Quasi-Newton) pode fornecer bons resultados para as estimativas dos parâmetros físicos de meios geológicos e geotécnicos em meios rasos. Além disso, essa combinação de métodos de inversão abre novas perspectivas para o processamento de dados georradar multi-canais. As investigações também mostram que a simulação dos perfis sintéticos por meio do método FDTD pode propagar erros em espessuras maiores de subsolo, devido ao fato de ser um método explícito. / This work deals with simulation of a 1-D electromagnetic wave propagating into a geological structure of known physical properties (thickness, electric conductivity and permittivity), the record of the reflected EM wave (synthetic data), and the use of these records in inversion and optimization algorithms to estimate back the physical properties of the geological structure. A stratified and thin (< 1.2 m) geological structure was initially constructed in order to be scanned by high frequency EM waves (800, 1000, and 1200 MHz). The EM wave propagation is simulated by Maxwell equations through FDTD method. The Quasi-Newton inversion and Ant Colony Optimization methods were applied into synthetic data to estimate original physical parameters of each geological layer. Both methods were applied in order to increase precision and convergence along depth. These methods were able to simultaneously estimate two physical properties of the geological structure: electrical permittivity and conductivity. The methods showed good results when applied simultaneously upon synthetic data of all three frequencies. Electric permittivity and conductivity profiles are shown with and without noise in the data. The results indicate that combined inversion methods can show good results to estimate physical properties of thin geological and geothecnical structures. The combined inversion methods open new perspectives to multichannel GPR data processing. The investigations also show that simulation of synthetic data through FDTD can propagate errors when dealing with thick geological structures, due to the fact that FDTD is an explicit method.