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    13379 research outputs found

    Study on Adversarial Robustness of Phishing Email Detection Models

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    Developing robust detection models against phishing emails has long been a main concerns of the cyber defense community. Currently public phishing/legitimate datasets are lack adversarial email examples which keeps the detection models vulnerable. To address this problem, we developed an augmented phishing/legitimate email dataset, utilizing different adversarial text attack techniques. In this work, the emails that can easily transform to adversarial examples and their unique characteristics have been detected and analyzed. Henceforth the models are retrained with adversarial dataset and the results show that ac- curacy from and F1 score of the models have been improved from five to forty percent under attack methods. In another experiment synthetic phishing emails are generated using a fine-tuned GPT-2 model. The detection model has retrained with newly formed dataset and we have observed the accuracy and robustness of the model has not improved under black box attack methods. In our last experiment we proposed a defensive technique to classify adversarial examples to their true labels using K-Nearest Neighbor with 94% accuracy in our prediction

    Studies in GPCR and Chromosomal Control

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    This dissertation is divided into two distinct parts. The first chapter is focused on regulation of serotonin receptors and signaling to address drug addiction, while the second chapter is focused on a novel synthetic approach towards a small molecule inhibitor of Ewing’s sarcoma. Drug addiction is a complex neurological illness that continue to plague society. While many neural networks are involved in the process, it is understood that serotonin receptors play a central role. Previous research has identified two serotonin receptors, 5-HT2AR and 5-HT2CR, to have a synergistic effect on cocaine-related impulsivity. Not only do they function as individual receptors in the process, but they also form functional hetero-dimers in which 5-HT2AR signaling is blunted. The goal of this research is to further probe the 2A:2C receptor system to better understand how they are involved in the relapse stage of drug addiction, as well as gain insight into the mechanisms and behavior of heterodimerization. This work was accomplished through novel syntheses of small molecule serotonin agonists and positive allosteric modulators targeting the two receptors, as well as peptide mimics of the transmembrane domains to control the receptor associations. Ewing’s Sarcoma is a malignant pediatric cancer found in bones and soft tissues. It is the second most diagnosed bone cancer found in children. Current treatment for this disease is limited as the origin and mechanisms of metastasis are poorly understood. Our collaborators at the Baylor College of Medicine performed high-throughput screening to identify potential small molecule regulators of this disease, in which they identified a lead compound which has a significant, selective effect on cell death for Ewing’s Sarcoma cancer cells. Original work on this molecule was hindered due to experimental challenges in this synthesis. The goal of this research was to develop a highly efficient and enantioselective synthesis to expediate future research

    The Effects of Instigation, Experiential Avoidance, and Emotion Dysregulation on Dating Aggression

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    Physical violence, psychological aggression, and cyber abuse are particularly prevalent in college student dating relationships. A behavioral theory of aggression and violent behavior, I3 Theory predicts that aggressive behavior and dating aggression are most likely to occur in the presence of three processes: instigating cues (e.g., provocation), aggressive-impelling forces (e.g., experiential avoidance), and diminished inhibition (e.g., emotion dysregulation). Recent research suggests that higher levels of experiential avoidance and emotion dysregulation may moderate the relation between provocation and dating aggression. However, no studies to date have examined these variables simultaneously. The purpose of this study was to test I3 Theory using an experimental test of aggression using the Voodoo Doll Task (VDT). College students (N = 269) listened to a neutral recording and then completed a behavioral measure of aggressive tendencies, the VDT. Participants then listened to a provocative jealousy induction scenario and again completed the VDT. Emotion dysregulation marginally accounted for the increase in aggressive tendencies on the VDT following provocation. Emotion dysregulation predicted use of physical, psychological, and cyber aggression, whereas experiential avoidance significantly predicted of cyber aggression

    Autism in Vietnam: A Three-Part Study to Enhance Understanding of Vietnamese Parents’ Perceptions and Etiological Beliefs about their Children’s Autism Spectrum Disorder

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    Background: Parents caring for autistic children have myriad demands ranging from initiating diagnostic procedures to selecting and implementing treatments. How parents make sense of the diagnosis of autism spectrum disorder (ASD) may influence their decision-making processes (cognitive processes), their emotional well-being, and their relational well-being. The Illness Perception Questionnaire-Revised for Autism Spectrum Disorder (IPQ-R-ASD) has been adapted and validated to measure parents’ perceptions and causal beliefs about their child’s autism. However, the validation sample was composed of parents living in high-income countries in North America (HICs; the United States and Canada) with individualistic cultural values. Perceptions and aforementioned cognitive, emotional, and relational experiences are also influenced by cultural values practiced by the family system as well. Nevertheless, similar to most autism research, including the IPQ-R-ASD validation study, parents from collectivistic cultures are largely underrepresented. Hence, it is unclear whether the IPQ-R-ASD is a useful instrument for understanding parents’ perceptions of autism from countries with collectivistic cultural values, such as Vietnam. Vietnam is a low-to-middle income country (LMIC) with collectivistic Asian cultural values, and parents in Vietnam may have cognitive representations of their children’s autism that differ from parents from individualistic HICs. Due to the scarcity of autism literature about Vietnam, the current study (a three-part dissertation) explored how autism and its causes are perceived by parents raising autistic children in Vietnam. Purpose: The overarching aim was to provide insight into parents’ autism perceptions and causal beliefs in Vietnam. Each study’s specific purposes were to (1) review the current state of autism research in Vietnam, including parents’ own experiences, autism practices, and governmental policies; (2) examine the psychometric properties of the Vietnamese IPQ-R-ASD for assessing parental autism perceptions; and (3) evaluate patterns and predictors of causal beliefs of autism among Vietnamese parents using the Vietnamese IPQ-R-ASD Cause scale. Methods: For Study 1, a scoping review was conducted using PRISMA guidelines, a critical first step in expanding the international understanding of autism in Vietnam. For Study 2, the translated Vietnamese IPQ-R-ASD was given to Vietnamese parents to analyze measurement invariance across Vietnamese and North American parent groups at the item, scalar, and factor levels. For Study 3, Vietnamese parents’ autism causal beliefs were explored using descriptive and factor analyses. Multivariate analyses of variance and multiple regression analyses were conducted to examine how parent characteristics (e.g., parent’s age) may predict their autism causal beliefs. Results: A scoping review of academic literature on autism in Vietnam revealed that many Vietnamese families of autistic children had a resigned outlook as they experienced a lack of autism-related support across all systems. Despite the challenges identified in the scoping review, included articles also highlighted Vietnamese parents’ self-empowerment, resilience, and innovation in caring for themselves and other parents (i.e., through creating parent support groups, developing parent-led schools to better support their autistic children). With regard to studies 2 and 3, data collected from this international sample (N=339 of Vietnamese parents) indicated that the translated, culturally adapted, and validated Vietnamese IPQ-R-ASD can be used meaningfully with Vietnamese parents in Vietnam. However, it must be interpreted within the sociocultural context of Vietnam and with reference to Vietnamese norms. Conclusion: This three-study dissertation offers previously unavailable information by not only showing the challenging situation of raising children with autism in Vietnam, but also the incredible resilience of Vietnamese families, even in the face of stigma and sparse resources in Vietnam. It also reveals the importance of cultural considerations when analyzing data from a standard measure given to cross-cultural populations, including developing cultural-specific norms for interpretation

    Noncognitive Factors and Transfer Student Academic Success

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    Background: Noncognitive factors, such as students’ academic engagement and achievement emotions, may be significant predictors of undergraduate student success. Information about these noncognitive factors within the context of transfer students is lacking. Transfer students comprise about half of all undergraduate students, yet their educational experiences may differ in meaningful ways from those of traditional students. Importantly, the transfer student population is not monolithic. Understanding this group is a complex and rich area of research, as transfer student status can intersect with other salient characteristics that may impede academic success, such as off-campus employment, enrollment status, or number of previous institutions (collectively referred to as “situational challenges”). Purpose: The goal of this dissertation is to understand how academic engagement and achievement emotions impact transfer students’ academic outcomes, as measured by term GPA and persistence. Methods: Manuscript 1 encompasses two studies and explores the relation of academic engagement, both cognitive and behavioral, for transfer students. The first study, examining cognitive engagement, draws data from an institution-wide survey administered at an urban, four-year institution (N = 721 undergraduate transfer students). Regression analysis is used to study the relation between cognitive engagement and transfer student academic success. The second study, focusing on behavioral engagement, uses data from two administrations of the National Student Survey of Engagement (NSSE) at the same university (N = 1,779 undergraduate transfer students). Mediation analyses is used to understand the impact of behavioral engagement on the relation between select situational challenges and academic outcomes for transfer students. Manuscript 2 includes one study examining the impact of two types of achievement emotions (enjoyment and anxiety) on academic success for transfer students. The study draws data from the same survey (N = 721 undergraduate transfer students) as Manuscript 1, Study 1. Regression analyses are used to study the relation between achievement emotions and transfer student academic success. Each analysis across both manuscripts is also further dissected by demographic characteristics including age, gender and race/ethnicity. Results: Consistent with other studies, cognitive and behavioral engagement predicted term GPA for transfer students. Cognitive engagement was not found to be a significant predictor of persistence for transfer students. Additionally, certain types of behavioral engagement, such as collaborative learning, student-faculty interaction, and high-impact practices, mediated the relationship between situational challenges, like working over 20 hours per week off campus, enrolling part-time or pursuing a STEM major, and term GPA for many subgroups of transfer students. Anxiety and enjoyment emotions individually predicted term GPA and persistence for transfer students. However, when controlling for anxiety emotions, enjoyment emotions were no longer a significant predictor. These relations differed across demographic groups. Conclusion: This dissertation provides evidence that noncognitive factors play a key role in transfer students’ academic success and provide further insight into how these factors differ across transfer student demographics. The implications of these findings and suggestions for interventions are discussed

    Beliefs of Immigrant Asian Science Educators Regarding Multicultural Science Education in the United States

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    Background: The increase of culturally and linguistically student population in the K-12 education has called for the teacher educators to prepare preservice teachers to address the needs of diverse students. Several teacher educations programs across the nation have adopted teacher training programs that focus on multicultural education. An understanding and implementation of multicultural education is not only informed by teacher preparation programs but is also influenced by teacher educators’ beliefs. Even today in countries like India and China, teaching science concepts is driven by traditional methods and dominated by a teacher-centered approach. Several immigrant educators are preparing preservice science teachers for diverse classrooms, yet researchers seldom tap into understanding their beliefs and practice. Purpose: The United States is considered the multicultural society. Nevertheless, the cultural diversity that immigrant educators experience in the India and China is significantly different from that in the U.S. Hence it is essential to understand the beliefs of immigrant science teacher educators about, as beliefs are informed by personal experiences and prior knowledge. Research Questions: (a) What are the beliefs of Asian science educators about multicultural science education in the context of the United States? and (b) How do their beliefs impact their practice? Methods: The data is primarily collected through open-ended surveys and semi-structured (virtual) interviews. Interview transcripts are transcribed through MS Stream and hand-coded to unpack the perceptions and beliefs as per Banks’ (1993) typology of multicultural education. The naturalistic inquiry focuses on how people behave in natural settings while engaging in life experiences. Credibility and trustworthiness are derived from the richness of the data gathered. Results: The participants discussed the terminologies they were referring to within their coursework, but it was not the use of the actual term multicultural education. The participants beliefs and understanding of multicultural science education is based on the fact: 1) that is science for all the students; 2) every student has the potential of understanding scientific knowledge, and 3) cultural diversity adds to the richness of the existing scientific ideas. The themes of generated from the data analysis are: 1) Standard-driven instruction; 2) Multicultural Education – a concept or a confusion; 3) Professional Development and 4) Educators with an ‘outsider’ identity. Conclusion: The participants suggested the concept of multicultural education ties to content areas of literacy and social studies. Limited time and opportunity serve as a significant barrier to including critical discussions essential for preparing preservice teachers for a diverse science classroom. Implications from this study call for intensive professional development opportunities to keep science teacher educators informed about the purpose of multicultural education. Further studies need to be conducted on unique constructs such as perceptions, knowledge, and attitudes of science teacher educators and how they are tied to multicultural science education

    Multimodal Imaging Combining Optical Coherence Tomography and Brillouin Microscopy to Study Neural Tube Biomechanics

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    This dissertation reports the development of a novel, non-invasive, all-optical, and co-aligned multimodal imaging technique which combines optical coherence tomography (OCT) and Brillouin microscopy to determine the structural and biomechanical properties of embryonic neurulation in a murine model. Mechanical forces play a major role during neurulation, and any disturbance can lead to severe birth defects such as spina bifida which result in lifelong disabilities after birth. Thus, it is very important to study the interplay between forces and tissue stiffness during neural tube development. OCT and Brillouin microscopy are high-resolution optical imaging modalities, where OCT provides structural information and Brillouin microscopy is capable of mapping tissue biomechanics. This multimodal approach enables mechanical characterization of the neural tube tissue in mouse models of neural tube defects. The first chapter of this dissertation introduces the importance of biomechanics for neural tube closure and available imaging techniques. The second chapter describes the development of a Brillouin microscopy system to characterize tissue mechanical properties and its validation using optical coherence elastography and the gold standard of uniaxial mechanical testing. The third chapter demonstrates the performance of the home-built Brillouin microscopy system by characterizing fresh and fixed mouse retinas. The fourth chapter demonstrates the development of the first-ever multimodal Brillouin-OCT system and illustrates its use in imaging the dynamic structure and changes in biomechanical properties of neural tube formation and closure in ex vivo murine embryos at different developmental stages. In the fifth and sixth chapters, the biomechanical properties of Mthfd1l and Fuz knockout mouse embryos are successfully assessed using the multimodal Brillouin-OCT system. Finally, this thesis concludes with ideas on improving the technical aspects of the system and future applications

    In Situ Microscopy Imaging of Biofilm Formation on Mannoside-modified Silicone Surfaces

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    The prevention of catheter-associated urinary tract infection (CAUTI) over long-term usage of urinary catheters remains a great challenge. Antibiotic resistance is an inevitable outcome of urinary catheterization and is closely associated with CAUTIs. An alternative approach is needed to combine broad-spectrum antibiotics, improved diagnostic, and surveillance techniques to prevent bacterial attachment to the catheter. Bacterial interference is a non-antibiotic-based strategy for CAUTI prevention using benign bacteria as living guards against pathogenic colonization on catheter surfaces. We proposed to pre-establish benign bacterial biofilm on the catheter surface to enhance the effectiveness of the bacterial interference strategy against urinary pathogenic colonization. Escherichia coli 83972 as a prophylactic agent has been utilized in several pilot-scale clinical studies for the prevention of CAUTI. The mannoside-presenting surfaces promote early-stage adhesion of an engineered strain of E. coli 83972 expressing type 1 fimbriae (denoted as fim+ E. coli 83972) terminated with FimH adhesin that binds mannoside derivatives. In this study, we modified the silicone surface with a series of mannoside derivatives and incubated the fim+ E. coli 83972 under both static and flow conditions. We showed that the bacterial adhesion and biofilm formation were directly related to the mannoside binding affinity. To systematically study the effect of the immobilized mannoside binding affinities on the biofilm formation at the early stage by fim+ E. coli 83972, we constructed a device allowing for in situ microscopy imaging with z-stack of the biofilm formation on the mannoside-modified silicone surfaces. The result of the quantitative analysis of the imaging data showed that the first layer of bacteria attached on a stronger binding affinity mannoside surface on silicone not only exhibited a higher coverage on the surface but also promoted the growth and stability of the upper layers. Finally, we showed that the silicone catheter surfaces coated with urinary proteins enabled the binding of wild-type E. coli 83972 without type I fimbriae under both static and flow conditions

    Disability Outcomes in a Public Charter School System: The Search for Consistency and Equity

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    Background: The Individuals with Disabilities Education Act (IDEA) requires schools to find and identify students with disabilities. Special education evaluations, Full and Individual Evaluations (FIE), are completed to identify and confirm eligibility for disability conditions. In the state of Texas, these FIEs are commonly completed by Educational Diagnosticians and Licensed Specialists in School Psychology (LSSPs). The guidelines for the identification of disabilities are vague at both the federal and state level, leaving room for interpretation by the individual evaluator. This may lead to the inconsistent identification of disabilities. The fidelity of evaluations can impact the services provided to students with disabilities and disproportionality of students who receive special education services. Purpose: The goals of this study were to analyze data from a large charter school system in the state of Texas to (a) describe the students in special education and their primary disability category, race, and gender, (b) describe the students in special education and their primary disability category, race, and gender within each of the individual districts within the large charter school system in Texas, (c) compare the differences of students with disabilities within the individual districts within the large charter school system in Texas. Methods: The sample for this study included students aged 6 through 21 who attended a charter school system in Texas on the fall PEIMS Snapshot date for the 2019–2020 school year. Deidentified student data was collected from the charter school system’s data management system and district demographic information was collected from the 2019-2020 Texas Academic Performance Report (TAPR). The design of this quantitative study was descriptive and causal comparative. Descriptive data and graphic representations of data were provided for visual analysis. Results: The overall charter system’s disability rates are inconsistent with national and state ratios. Both gender and racial disproportionalities existed within the charter school system as a whole. When investigated individually, the districts had inconsistencies in the identification of disabilities. Gender and racial disproportionality existed within each district. Although some primary disability conditions were more conducive to gender equality, all had more males identified than females. Generally, Hispanic students are overidentified with specific learning disability, Black students are overidentified with intellectual disability, and white students are overidentified with emotional disturbance. Conclusion: The charter school system followed some trends consistent with literature and had trends in direct opposition of most literature. Overall, there were inconsistencies in the proportions of students identified with disabilities in each district in both race and gender. The data gathered and these areas of inconsistency are the first areas to target moving forward


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    A high engineering critical density (Je) rare-earth barium copper oxide (REBCO, RE-Ba2Cu3O7-δ) superconductor can immensely increase the magnetic field as well as reduce the cost of ultra-high-field magnets because of its high current-carrying capacity, high irreversibility field, and good mechanical properties. An advanced metal–organic chemical vapor deposition (A-MOCVD) tool based on the ohmic heating technique was developed to grow 4–5 µm thick REBCO films. We demonstrated short REBCO samples with Je ~4,600 A/mm2 (based on a 0.1-mm thick tape) at 4.2 K, 20 T. The next imminent goal was to scale up these high performance samples to 50-meter lengths. The first section of this work addresses the engineering challenges associated in scaling up the length of 4+ µm thick REBCO film tapes in a single pass using A-MOCVD. The processing recipes were optimized for growing high-performance, thick REBCO films for 4.2 K and 13 T as well as 65 K and 1.5 T applications. The dropout or variation in the critical current along the length of long tapes have been correlated with process parameters. After the desired modification of the A-MOCVD tool based on the correlation, we fabricated uniform >10-m-long REBCO tapes in our R&D A-MOCVD tool. Later we transferred this knowledge to a pilot-scale A-MOCVD manufacturing tool to make 50-m long, 5% Zr-added REBCO tapes with film thickness exceeding 4 µm, in a single pass. A compositional map was constructed to guide the fabrication of 50-meter-long tapes with uniform critical current (Ic) over 1,750 A/12 mm at 65 K and 0.25 T. Three preliminary experiments were performed in R&D A-MOCVD to facilitate the design of the next-generation A-MOCVD tool. First, the influence of the higher reactor processing pressure on the Ic of 4 µm thick REBCO films was investigated. Second, the growth of epitaxial REBCO films in the modified reactor with a longitudinal vapor flow setup was studied. Finally, double-sided REBCO tapes with 2 µm film thickness on each side of the substrate was developed with an overall tape self-field critical current density (Jc) over 2.5 MA/cm2 . Double-sided REBCO tapes have the potential to reach 10 times the Ic of commercial REBCO tapes and precursor conversion efficiency over 70%


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