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RBMS3 belongs to the family of c-myc gene single-strand binding proteins (MSSPs) that play important roles in transcriptional regulation. Here, we show that RBMS3 functions as a tumor promoter in triple-negative breast cancer (TNBC), a highly aggressive BC subtype. Analysis of RBMS3 expression shows that RBMS3 is upregulated at both mRNA and protein levels in TNBC cells. Functionally, overexpression of RBMS3 increases cell migration, invasion and cancer stem cell (CSC) behaviors. Moreover, RBMS3 induces expression of epithelial-mesenchymal transition (EMT) and CSC markers. Conversely, loss of RBMS3 in TNBC BT549 cells inhibits cell proliferation, migration and mesenchymal phenotype. Correlation analysis shows RBMS3 is associated with TGF-β signaling. Mechanistically, RBMS3 interacts with Smad2, Smad3 and Smad4 mRNA and regulates the stability of these transcripts. Importantly, RBMS3 prevents TGF-β-induced cytostasis and apoptosis in premalignant cancer cells. Moreover, RBMS3 inversely correlates with expression of ESRPs, epithelial-specific splicing regulatory proteins that regulate morphogenesis-associated alternative splicing events. ESRPs appear to suppress EMT through distinct mechanisms: ESRP1 restricted cell migration, whereas ESRP2 prevented cell growth. RBMS3 significantly facilitates the EMT process when ESRPs are lost. Collectively, the studies within this dissertation identify RBMS3 as a positive regulator of EMT and breast cancer progression by regulating the TGF-β signaling pathway.

Spermatogenesis is the process by which mature functional spermatozoa are formed, and is initiated in the stem cell niche of the testes. During the post-meiotic stage of spermatogenesis, spermiogenesis, transition proteins facilitate the transformation of chromatin from a histone-based nucleosome structure to a protamine-based nucleosome structure. This study is aimed at analyzing genomic, transcript, and protein sequences of transition proteins in 13 sequenced Drosophila species. The Drosophila melanogaster spermatid specific transition protein-like protein (Tpl94D) was used as the reference sequence in this study. An extensive bioinformatics approach was employed in establishing the Tpl94D orthologs. We identified Tpl94D orthologs in the melanogaster subgenus (D. simulans, D. sechellia, D. erecta, and D. yakuba), D. ananassae, D. miranda, and D. pseudoobscura. In contrast, no Tpl94D orthologs were identified in D. persmilis, D. willistoni, or the Drosophila subgenus (D. mojavensis, D. virilis, and D. grimshawi) due to their evolutionary distance from D. melanogaster. Differential gene expression analysis of the testes versus the ovaries showed high expression of Tpl94D orthologs in the testes for in D. melanogaster, D. simulans, D. yakuba, D. ananassae, D. miranda, and D. pseudoobscura. Further RNA-Seq analysis using the NIH Isoform Two-Step Analysis revealed higher testes expression for D. melanogaster Tpl94D isoform A (164 amino acids) than D. melanogaster Tpl94D isoform B (163 amino acids). We confirmed the conservation of a HMG box/DNA binding domain among transition protein (Tpl94D ) orthologs and Drosophila male specific transcript protamine-like protein (MST35Ba/MST35Bb) orthologs. Overall, this study represents the first large-scale, single-genus invertebrate dataset for transition proteins and provides the basis for a fine-grained analysis of their evolution.

The main purpose of this research study was to explore the potential application of polarimetric principles in characterization and monitoring of space materials. Space monitoring and collision avoidance between space vehicles and inter-space debris has become a major concern for space agencies and authorities maintaining satellites, space shuttles and stations. Inter-space debris can be man-made or natural. As the quantity of space debris increases, tracking and collision avoidance becomes a critical issue. The novelty of this study consists in the single pixel analysis of back scattered optical polarimetric signatures from various space materials. Surface characterization of different materials was performed by analysis of their polarization response. The study employed single-pixel detection of back scattered laser beam polarimetric signatures obtained from different materials. The back scattered optical polarimetric signatures contained major information related to geometry, texture and composition of the material. The DOLP (Degree of Linear Polarization) algorithm was applied to analyze polarization response from the different materials used in this study. Different materials used in space vehicle design were examined and the DOLP ratio was calculated at different material and detector orientations. On examining Teflon, which is a soft polymer material used in space vehicle design, we observed high depolarization of light. This was due to the “Diffuse reflectance” nature of Teflon at different object orientations. Hence, Teflon can be identified as a “Lambertian surface” exhibiting high depolarization of light. The polarization response exhibited by materials such as windowless polysilicon solar panel and a wooden stick painted in white color mixed with titanium dioxide was found to be similar to the response exhibited by Teflon. It was observed that the extent of depolarization exhibited by different materials was found to be distinct and depended on material composition.Materials such as Kapton and shiny aluminum foil exhibited sharp backscattered intensity distributions with high polarization of light at different orientations. The sharp back scattered intensity distributions of Kapton and shiny aluminum foil indicated their high polarization and “Specular reflectance” nature. Different metallic materials such as roughened aluminum, molybdenum and stainless steel were examined. It was observed that the backscattered distributions exhibited by roughened aluminum, molybdenum and stainless steel were broadened curves with distinct depolarization signatures. The depolarization exhibited by roughened aluminum was due to discontinuities present on its surface.Windowed solar panels made of amorphous silicon and polysilicon materials were tested and it was observed that both of the panels exhibited similar sharp backscattered distributions. It was observed that the amorphous silicon solar panel exhibited higher depolarization of light than the polysilicon solar panel.The experimental results indicated that single pixel polarimetric imaging can effectively sense and characterize various space materials based on the amount of optical depolarization and backscattered intensity distributions; suggesting its potential application in space research and sensing, with emphasis on the monitoring of space objects.

Digital wideband receivers are essential elements used in electronic warfare (EW) applications. Instantaneous Frequency Measurement (IFM) receivers are suitable for use in EW systems due to the ultrawide instantaneous radio-frequency (RF) bandwidth, fine-frequency resolution, and moderately high sensitivity and dynamic range. Conventional IFM receivers use analog components such as power dividers, crystal video detectors, and hybrids. This research presents the architecture and design implementation of a purely digital IFM receiver based on a patented algorithm courtesy of the United States Air Force. The invention is capable of detecting a short wave pulse with 1 MHz error for every 100 nsec. The benefits include a compact, lightweight, cost-effective alternative to its analog counterpart. The design was implemented and tested on Delphi’s ADC3255 (a PMC digitizer with Xilinx Virtex 4 FPGA). The outputs were verified using Xilinx’s ChipScope Pro.

Polymer Matrix Composites (PMC) are increasingly favored in structural applications for their light weight and durability. However, the numerical modeling of these materials poses several challenges. This is primarily due to the highly anisotropic nature of the creep exhibited by these materials above the glass transition temperature. Also, the damage and failure of the material is of particular interest to designers using the PMCs. Recently, a sustained effort has been to provide the designer with large computer codes containing comprehensive constitutive equations, often equipped with large number of internal variables and with the most general mathematical forms, for use in structural design analysis. Although elegant and useful, such constitutive laws are often expensive in implementation. Specially for early stages of the design, a quicker way of estimating complicated PMC behavior is needed. In this work, the constitutive material law by Robinson and Binienda (2001) [1,2] is utilized for such an approach. The model is successful in describing polymer matrix composite (PMC) materials having long or continuous reinforcement fibers embedded in a polymer matrix. Although the material law includes a single scalar parameter to describe the damage, it retains the essential material behavior. The material law is implemented computationally as a user defined subroutine (UMAT) in a commercially available FEA code (ABAQUS). The material parameters are obtained from experiments of thin-walled tubular specimens reinforced with unidirectional, helical fibers at an angle , and under tensile and shear loading . The model correctly predicts the relation between logarithmic creep rate and logarithmic stress. The user subroutine has robust convergence properties. The creep strain rate and the effect of damage on the creep strain rate are presented for the benchmark problem of a square plate with a circular hole at the center and pressure vessel. The effect of fiber orientation on the durability of the square plate and pressure vessel under damaging loads, is studied.

The objective of this study was to determine whether grain boundary deformation plays a direct role in intergranular stress corrosion cracking of Ni-16Cr-9Fe in high temperature water. The difference in deformation and cracking behavior between special grain boundaries, or coincident site lattice boundaries (CLSB), and high angle boundaries (HAB) is exploited to determine if a cause-and-effect exists between grain boundary deformation and IGSCC. It was hypothesized that coincident site lattice boundaries (CSLBs) are less susceptible to deformation than general (random) high angle boundaries (HABs), and are, therefore, less susceptible to cracking. The hypothesis was substantiated by showing that (1) the dislocation absorption kinetics differs substantially between CSLBs and HABs, resulting in different susceptibilities to deformation, and (2) grain boundary deformation is a precursor to intergranular cracking. The difference in dislocation annihilation kinetics at CSLBs and HABs was determined by TEM on samples annealed at 360°C. Results showed that extrinsic grain boundary dislocations (EGBDs) are annihilated at HABs at a rate that is, on average, 3 times that at CSLBs, implying a grain boundary diffusion coefficient in CSLBs is 12 times lower than that in HABs. The expectation that a reduced EGBD absorption at CSLBs would lead to greater matrix hardening was investigated using nanohardness measurements. Results showed that the hardness in the vicinity of CSLBs is greater than near HABs, and the sample-average hardness increases with the fraction of CSLBs. The difference in deformation behavior was investigated by SEM examination of samples strained at 360°C in an inert environment. Following 10% plastic straining in 360°C Ar, 52% of the HABs and 15% of the CSLBs were found to display deformation. The relationship between grain boundary deformation and IGSCC was demonstrated by further exposing these samples to 5% strain in 360°C primary water. Resulting analysis showed that 61% of the boundaries that deformed in argon also cracked in water while only 17% of cracked boundaries showed no prior deformation in argon. These results show that there is a cause-and-effect relationship between grain boundary deformation and IGSCC.

Steam generators in pressurized water nuclear power plants have experienced significant problems with intergranular stress corrosion cracking (IGSCC) on the inner diameter of steam generator tubing for over 25 years. In the course of research to understand IGSCC, it has been shown that creep deformation may play a significant role in the cracking of commercial Alloy 600 (Ni-16Cr-9Fe-0.03C). The primary water environment can cause decreases in creep resistance (i.e., faster creep rates, shorter time to failure, and higher creep strains). During corrosion under the conditions of interest, both hydrogen reduction and metal dissolution occur. One or both may contribute to the enhancement of creep. The purpose of this work was to isolate the mechanism by which the water environment causes the creep deformation to increase. Activation area and activation enthalpy for glide were measured in argon and primary water on high purity Ni-16Cr-9Fe alloys. The results indicated that the activation area was reduced by primary water, consistent with a hydrogen enhanced plasticity mechanism for enhanced creep. The stress dependence of creep was also examined in argon and primary water. The results indicated that the internal stress of the alloy is reduced by the primary water environment. Lower internal stress is consistent with both a hydrogen model as well as a vacancy-aided climb model for enhanced creep. To isolate the effect of hydrogen on the creep of the alloy, experiments were conducted in a dissociated hydrogen environment. The results indicated that hydrogen would only increase the steady state creep rate if present before loading of the samples. However, if the sample was already in steady state creep and hydrogen introduced, a transient in the creep strain was observed. The creep rate returned to the original steady state rate in a short time. The results indicate that while hydrogen does affect the steady state creep to an extent, hydrogen cannot completely account for the increase in creep rate observed in primary water. Also, the presence of the aggressive environment before loading appears to be required to increase the creep rate, indicating that the effect of environment may be significant in the primary creep regime.

We have used multi-wavelength VLBA and MERLIN observations of 32 compact extragalactic radio sources within 30° ≤ l ≤ 77°, |b|