The alongshore variability of beach-dune systems and the response and recovery from extreme storms remains poorly understood. The height and extent of foredunes along barrier islands varies over a range of spatial scales, implying that during extreme storms, the beach-dune system should respond in different ways depending on the elevation and volume of the dunes relative to the storm surge. The purpose of this study is to use Ground-Penetrating Radar (GPR) and vibra-cores to investigate the internal structure of small, intermediate and large dunes along a 2.5 km transect of beach in Padre Island National Seashore, TX with particular attention to storm impacts. A series of dune normal and parallel GPR profiles were collected to capture the variation in beach-dune morphology at the three sites. Site locations were chosen along a transition from dissipative to intermediate beach states. Following the Sallenger (2000) storm impact model, the small dune is defined by low-lying topography that is susceptible to overwash and inundation depending on the size of the storm surge. The large dune is characteristic of the “collision regime”, while the intermediate dune represents a transition between “overwash” and “collision regimes”, with the underlying assumption that all three dunes would be impacted by the same level of surge during a single storm event. Results from the GPR survey suggest that each site contains a bright, laterally continuous radar reflector that is interpreted with the aid of the sedimentary data as an erosional layer. Different characteristic radar facies and sequence boundaries provide evidence as to how each dune evolved through and after the storm. Results from XRF scans and grain size analysis show a direct comparison between the GPR reflectors at the storm surface and spikes in calcium counts from XRF scans to distinct changes in grain size parameters at the same depth. It is argued that the location of each shell layer corresponds to a storm surface generated during a single storm, which means it is possible to interpret different recovery mechanisms. The presence of the storm layer across the backbeach and dunes provides evidence for the height and extent of the surge during the storm event. The data suggests that the small dune was overtopped by the surge, experiencing minimal erosion and recovery. The intermediate dune was completely eroded by the surge, but showed the greatest recovery of all the dune sites. The large dune was scoured at the base with marginal impact along its crest and shows minimal recovery after the storm. These results suggest that the evolution (i.e., transgression) of a barrier island varies considerably over short distances.

This thesis presents an analysis of the behavior of an equiangular spiral antenna using a mixture of numerical and measurement techniques. The antenna is studied as an isolated element and as a part of a spiral-based ground-penetrating radar (GPR) detection system. The numerical modeling was based on the parallelized finite-difference time-domain method and the model was validated by comparison with a prototype antenna and detection system. The intention is to isolate the effect of varying different geometrical parameters that define the spiral element or the spiral GPR system. With some notion of each parameter's effect, systems that use the spiral antenna can be designed more easily. The analysis of the spiral antenna in isolation provides a set of design graphs for the antenna. A set of design graphs are constructed that allow one to better understand the effect of the chosen dielectric substrate on the characteristic impedance of the antennas. A second set of design graphs give very specific data about the lower cut-off frequency possible for the antennas given a requirement on its minimum boresight gain, axial ratio, or voltage standing-wave ratio when matched with an appropriate transmission line. The analysis of the spiral antenna in the context of a detection system provides information on the effect of the ground on the GPR system and to what extent the circular polarization properties of the spiral antenna play a role in GPR. It is shown that a spiral antenna used in a monostatic radar configuration will reject a symmetric scatterer well into the near-field. The importance of a resistive loading to the spiral arms is demonstrated for this rejection to be optimal. In addition, it is shown that increasing the dielectric constant of the ground narrows the pattern and polarization properties, making the antenna more directive towards boresight when the spiral antennas radiate into a flat ground. In addition to this work, a method for reducing the truncation error when calculating the planewave spectrum of an antenna is described.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 114-121). Also available on the Internet.

Thesis (M.A.)--Portland State University, 2002. / Computer-produced typeface. Includes bibliographical references (leaves 119-123).

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 114-121). Also available on the Internet.

Measuring the relative apparent dielectric permittivity of the subsurface is an easy and inexpensive way to indirectly obtain the volumetric water content. Many of the instruments that measure the dielectric, specifically borehole ground penetrating radar, rely on the travel time of an electromagnetic wave through a moist soil. Through inversion of the travel time, the water content can be calculated provided the path over which the wave travels is known exactly. In traditional interpretations of water content, the travel path of the electromagnetic wave is assumed to be direct from the transmitting antenna to the receiving antenna, irregardless of the propagation velocity structure. A new analysis is presented for the interpretation of first arrival travel time measurements from borehole ground penetrating radar during zero-offset profiling that considers critically refracted ray paths. By considering critical refraction at interfaces between contrasting propagation velocities, the travel path becomes dependent upon the velocity structure. Several infiltration experiments were performed to test whether critical refraction occurs in the subsurface. The infiltrating water will change the velocity structure of the subsurface in a predictable manner The interpretations of travel time were then compared to predictions made with an unsaturated flow model and supporting instrumentation. It was found that when critical refraction was not considered, the volumetric water content was underestimated by up to 30%. Correcting for critical refractions, therefore, becomes an important step in properly characterizing the subsurface. The new analysis presented herein may improve our ability to use direct measurements in water resource management practices to assess water availability in semi arid regions.

Delivery of macromolecules into mammalian cells in vitro and in vivo has enabled new areas of research and offers the potential for powerful new treatment options. Recent research has generated many delivery platforms but these solutions remain limited by scope, potency and safety. We have reported a superpositively charged green fluorescent protein (+36 GFP) with the ability to deliver nucleic acids into a variety of mammalian cell lines in vitro and to potently deliver protein in vitro and in vivo without toxicity. These results have directed us to identify a subset of naturally occurring human proteins with similar but previously unknown cell-penetrating and protein delivery properties. Preliminary efforts have been made towards establishing the therapeutic potential for supercharged proteins replacement of the cytosolic enzyme, argininosuccinate synthase. Preliminary efforts have also been made towards enhancing endosomal escape with \(His_{39} GFP\).

Adenovirus serotype 5 (Ad5) is widely used as an oncolytic agent for cancer therapy. However, its infectivity is highly dependent on the expression level of coxsackievirus-adenovirus receptor (CAR) on the surface of tumor cells. We engineered Ad5 virus with the protein transduction domain (PTD) from the HIV-1 Tat protein (Tat-PTD) inserted in the hypervariable region 5 (HVR5) of the hexon protein in the virus capsid. Tat-PTD-modified Ad5 shows a dramatically increased transduction level of CAR-negative cells and bypassed fiber-mediated transduction. It also overcomes the fiber-masking problem, which is caused by release of excess fiber proteins from infected cells. To achieve specific viral replication in neuroblastoma and neuroendocrine tumor cells, we identified the secretogranin III (SCG3) promoter and constructed an adenovirus Ad5PTD(ASH1-SCG3-E1A) wherein E1A gene expression is controlled by the SCG3 promoter and the achaete-scute complex homolog 1 (ASH1) enhancer. This virus shows selective and efficient killing of neuroblastoma cell lines in vitro, and delays human neuroblastoma xenograft tumor growth on nude mice. To further enhance the viral oncolytic efficacy, we also switched the fiber 5 to fiber 35 to generate Ad5PTDf35. This vector shows dramatically increased transduction capacity of primary human cell cultures including hematopoietic cells and their derivatives, pancreatic islets and exocrine cells, mesenchymal stem cells and primary tumor cells including primary cancer initiating cells. Ad5PTDf35-based adenovirus could be a useful platform for gene delivery and oncolytic virus development. Viral oncolysis alone cannot completely eradicate tumors. Therefore, we further armed the Ad5PTDf35-D24 virus with a secreted form of Helicobacter pylori Neutrophil Activating Protein (HP-NAP). Expression of HP-NAP recruits neutrophils to the site of infection, activates an innate immune response against tumor cells and provokes a Th1-type adaptive immune response. Established tumor on nude mice could be completely eradicated in some cases after treatment with this virus and the survival of mice was significantly prolonged.

Conjugation of the Human Immunodeficiency Virus Transactivator of Transcription (TAT) to active proteins allows transport into the intracellular environment. This feature can be harnessed to deliver combinations of reprogramming factors (RFs) such as c-Myc, Oct4, Klf4 and Sox2 into somatic cells to derive induced pluripotent stem cells (iPSCs). For this project, TAT-fusion proteins including four TAT-conjugated RFs (TAT-RFs) have been produced and purified. All four TAT-RFs can bind specific DNA sequences. Bioactivity was tested in live cells using a novel assay based on an engineered fibroblast cell line that can be induced to express RFs by doxycycline and subsequently generate iPSCs. To test each TAT-RF, reprogramming was blocked by transient silencing of a single RF by siRNA and rescued by the corresponding TAT-RF. The results of this assay suggested that TAT-Klf4 was bioactive in cells; however, definitive evidence could not be obtained for other RFs.

High latitude soils are estimated to store a considerable part of the global pool of soil organic carbon (SOC). Studies of global and regional SOC pools have estimated total inventories in northern Sweden’s subarctic region to fall within 10-50 kg m-2. However, correction factors for stone and boulder content of soils are often overlooked in SOC-studies and soil profiles are commonly normalized to a depth of 1 m, which can result in substantial overestimates of the SOC pool if a large part of the soil volume is occupied by stones/boulders or if the soil depth is shallower than 1 m. This study was performed to quantify SOC in soils of the Torneträsk catchment area using detailed measures of soil depth and stone/boulder contents. Two non-destructive sampling methods, ground penetrating radar (GPR) and rod penetration, were used to measure soil depth and stone and boulder content in the catchment area. Results show that average soil depth (n = 52344) varied between 0.95 – 2.14 m depending on elevation and the average mire depth was 0.63 m. Stone and boulder content of the soil was estimated to 49 – 68 % depending on elevation. The results were added to existing carbon and soil density data from the Torneträsk catchment area and total SOC inventories were calculated to 6.8 – 13.1 kg m-2. The results of this study indicate that previous studies on regional and global scale may have overestimated the SOC pools in the subarctic regions of northern Sweden.