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Investigating Faculty Perspectives on Written Qualifying Exams in Physics
Get PDFDoctoral qualifying exams are considered essential in assessing a student's readiness for research and advanced studies. Despite their significant role in many physics’ programs, questions have been raised about their format, execution, and relevance. Our research investigates perceptions held by faculty members regarding the Graduate Doctoral Examination (GDE), a written qualifying exam in Auburn University's physics department doctoral program. We used a combination of semi-structured interviews and a survey to probe their viewpoints about the purpose and necessity of written qualifying exams, their role in student preparation for these exams, and the efficacy of these exams in measuring students’ comprehensive knowledge and potential for success in physics. Despite the general consensus on the necessity of the GDE, faculty members expressed doubts about its ability to accurately predict students’ future research success and its alignment with other graduate program elements such as coursework. Proposed modifications ranged from an emphasis on oral assessments and research presentations to a complete overhaul of the examination structure. Despite these suggestions for change, the lack of agreement on a specific alternative underscores the complexity of executing substantial modifications to the GDE. Our study contributes to the ongoing dialogue on optimizing doctoral qualifying exams to better serve students and academic institutions
LEO Aiding for a Barometric Map-Matching Pedestrian Dead Reckoning Solution in a GNSS Inhibited Environment
No full textThe current pedestrian navigation space has become increasingly reliant on Global Nav-
igation Satellite Systems (GNSS) as their sole form of navigation. However, GNSS signals
are quite vulnerable to intentional and accidental interference. When a pedestrian loses their
only navigation solution the can be left in very confusing and potentially dangerous scenarios.
Thus, there is a growing need to develop pedestrian navigation systems that operate entirely
independent of GNSS information. One way to circumvent the need for GNSS navigation is
to used a localized inertial navigation system (INS). Specifically, a step detection approach to
pedestrian dead reckoning (PDR) allows for the propagation of a pedestrian’s position solution
using only the measurements of an inertial measurement unit (IMU). In this algorithm, angular
velocity and specific force measurements are used to calculate a heading and step length which
are transformed into a position over time. However, the noise inherent to IMU measurements
creates a drift on this PDR position estimate. Depending on the magnitude of noise in the
system, this drift can significantly degrade the quality of the navigation solution.
This thesis presents a series of sensor fusion algorithms that reduce the errors in the PDR
system. To start, low Earth orbit (LEO) satellite information is used to estimate the errors on
the calculated heading measurement. In this methodology, LEO Doppler shift measurements
are used to derive the pedestrian’s course. By comparing this course to the heading output by
IMU measurements, a heading bias is estimated when at least two Doppler shift measurements
are available. This heading bias estimation technique is tested and evaluated for both a static
and dynamic heading bias. The other sensor fusion algorithm presented in this thesis is a novel
implementation of a barometric elevation map-matching algorithm. This map-matching system
uses the differential between a barometer measurement and an elevation pulled from a digital
elevation map (DEM) to constrain position errors. Traditionally, this algorithm has experienced
computational issues on low size, weight, and power (SWaP) hardware due to the chosen esti-
mation framework and DEM. The barometric elevation map-matching algorithm in this thesis, however, is evaluated with a variety of nonlinear estimation filters and open source DEMs to
maximize the system’s computational efficiency while maintaining position accuracy. Addi-
tionally, this map-matching algorithm does not estimate a heading bias which helps to alleviate
some of the algorithm’s computational burden. Each of these two sensor fusion algorithms
are individually evaluated using a series of Monte Carlo analyses in a simulated environment.
The results of these studies validate the sensor fusion algorithms for a variety of pedestrian
navigation systems. These methodologies are then combined into a singular system that aims
to constrain the errors on the PDR position output. This combined sensor fusion algorithm is
evaluated in both a simulated and more realistic testing environment. In both the simulated and
pseudo-live data testing scenarios, the combined sensor fusion algorithm is shown to reduce
the position error to within only a few meters of error. An accurate position solution for a
pedestrian is determined without the use of any GNSS information
STEM Summer Bridge Programs: Implications for College Counseling and Social Justice in Higher Education
Get PDFEthical counselors promote social justice (American Counseling Association, 2014). Based on counselors’ specialty and site of practice, promoting social justice involves different goals and methods. One way for college counselors to promote social justice is to support students from groups historically excluded from higher education at their institution. Based on multiple personal identities, higher education is not representative of the overall US population (National Center for Education Statistics, 2023). The greatest driver of the underrepresentation of students from historically excluded groups is retention (Shaw et al., 2021). The Culturally Engaging Campus Environments model of student retention (CECE; Museus, 2014) asserts that institutions and their agents, e.g., college counselors, should engage their diverse student population’s cultural selves to support student retention. One program which was designed to be congruent with the CECE model is the Auburn University STEM Summer Bridge program (SSB; Gonzales et al., 2022). The present study used a quantitative, repeated measures design to investigate if participation in an SSB improved participants’ academic self-efficacy (ASE) confidence and stress, sense of belonging to the STEM fields generally, and sense of inclusion within their college. Participants (N = 156) were primarily 18 years of age (n = 147, 94.6%) and most identified as Black/African American (n = 105, 67.3%). Results indicated a significant change in participants’ ASE confidence and sense of belonging to STEM before and after completing SSB. Possible explanations of nonsignificant ASE stress and sense of inclusion findings and implications to inform college counselors’ praxis are also discussed
Fast and Ultrafast Pulsed Laser Post-processing of Zinc Oxide Thin-films Deposited on a Thermally Resilient and Thermally Sensitive Substrate
No full textThis manuscript is split into two projects. The first project is on nanosecond laser annealing of radio-frequency magnetron sputtered zinc oxide thin-films on a silicon dioxide/silicon substrate. The films were sputtered to be approximately 100 nm thick and of a mostly amorphous nature with the composition theorized to be composed of pockets of noncrystalline grains embedded in an amorphous matrix. The samples were then laser annealed using four wavelengths at 1064 nm, 532 nm, 355 nm, and 266 nm over a range of fluences (20-3000 mJ cm−2) with the limiting end corresponding to ZnO ablation for that wavelength. In the case of 1064 nm and 532 nm the fluence range was extended to include near silicon ablation. They were then evaluated using X-ray diffraction (XRD), Rutherford backscattering (RBS), and scanning electron microscopy (SEM). A simulation was also run to investigate peak temperature reached during the lifetime of the pulse for each wavelength and fluence. The X-ray diffraction results showed no positive change in the crystalline nature of our films for wavelengths below the bandgap (1064 and 532 nm). The above bandgap wavelengths (355 and 266 nm) showed very strong crystallization, reaching a highest grain size of approximately 33 nm, a notable grain growth from the 17 nm as-sputtered sample for 355 nm. Rutherford backscattering results displayed an approximate 1:1 oxygen/zinc ratio using the 355 nm wavelength at the highest fluence, similar to the oven annealed set. For 266 nm there was a trend for over-saturation of oxygen in the films, showing a approximately 1.4/1 O/Z ratio. Scanning electron microscopy showed spherical nanostructures of various sizes appearing during irradiation with the 355 nm wavelength, with a relatively smooth and homogeneous surface in between. While the 266 nm wavelength showed both spherical and rope-like nanostructures along with nano-holes pitting the surface. The theoretical results showed that the UV wavelengths and fluences chosen probed a wide range of temperatures from low temperature to near melting for ZnO. The laser annealing took only two minutes compared to the roughly 4+ hour oven annealing process. Overall, notable improvement to the films structural, crystallographic, morphological, and chemical changes were made from laser annealing at a 355 nm wavelength for a fluence range between 160-240 mJ cm−2. This clearly shows that laser annealing at this wavelength and fluence range iiis the preferred alternative for post-processing as opposed to the furnace. Sol-gel spin-coated samples were also laser irradiated in this experiment but no discernible improvements can be seen attributing to the introduction of chemical contaminants inherent to the process. The second project is on femtosecond laser annealing of radio-frequency magnetron sputtered zinc oxide thin-films deposited on a indium tin oxide/polyethylene terephthalate substrate (plastic). The smaller pulse width, in comparison to the nanosecond laser, will be used to induce a more localized, controlled heating to avoid damaging the underlying plastic substrate in the laser annealing process. The ZnO films were sputtered to be approximately 100 nm thick and of the same nature as the last project. To determine what fluence should be used to laser anneal these samples at the ultra-fast timescale, a hybrid two temperature with carrier dynamics model was constructed. This model combines the two temperature model with the 1D heat diffusion model to create a more computational efficient simulation while still creating simulated results agreeable with experimental outcomes. After, this fluence range was then experimentally used to laser anneal our samples at a wavelength of 266 nm using a femtosecond pulsed Ti:Saphire laser. The resulting structural, crystallographic, and morphological characterization was done with X-ray diffraction and atomic force microscopy. It was shown that improvements to the film quality was made using our chosen fluences from X-ray diffraction, showing results comparable to low temperature oven annealing (≈ 300 °C) which cannot be achieved by direct placement of the composite into the furnace. Atomic force microscopy shows a relatively low RMS surface roughness was maintained while producing ordered nano-pillar structures on the film. The results of this project show that the low heat affected zone inherent to ultrafast laser post-processing is a key component of this viable method to treatment of films or devices based on fragile, low-temperature substrates such as plastic which cannot be post-processed in conventional methods like furnace annealing
Parental Bereavement as a Form of Trauma in College Students: Personal Contexts and an Institution’s Role in Healing
No full textThis qualitative study aims to understand how college students navigate parental loss and how institutions are helpful or harmful during the healing process. Utilizing a constructivist case study approach, data were collected from three participants through semi-structured interviews, document analysis of participant-generated artifacts, and institutional website reviews. Each participant identified multiple contexts impacting the loss of their parent. Findings revealed that the experience of parental bereavement is unique and complex, marked by identity concerns, challenges in healing, and the lasting impact of the parent-child relationship. Students also reported difficulties with non-linear experiences and memory issues following loss, suggesting the need for a nuanced understanding of the ecological context. Practice recommendations include implementing clear referral processes for bereaved students, creating comprehensive resource lists, providing ongoing support, establishing formal bereavement leave policies, and fostering trauma-informed practices among institutional actors. Future research could explore institutional readiness to support grieving students and expand investigations of parental loss to encompass diverse parental figures and cultural backgrounds. A lack of racial diversity and geographic concentration within the southeastern United States limits the study
Effects of a Split-Root Hydroponic System on Salinity Tolerance of Tomatoes
No full textTomatoes are the most produced greenhouse crop globally and are loved due to their nutritional and health benefits. Meanwhile, the production of saltwater fish is on the rise, with consumers willing to pay premium prices for these species. Given the profitability and market demand for both saltwater fish and tomatoes, combining their production systems could significantly enhance overall profitability. One viable option is brackish water aquaponics, which integrates the cultivation of saltwater fish with high-value plants such as tomatoes. The primary challenge is that saltwater fish require different salinity levels than tomatoes, which can significantly reduce the yield and productivity of the tomatoes. Two studies were conducted using the split-root system to explore the feasibility of integrating these two systems. The first study used the split-root system to investigate the salinity threshold of ‘Washington’ cherry tomatoes under three salinity levels 0 parts per thousand (ppt), 4.5 ppt, and 9 ppt, under two root conditions: homogeneous (Homo) and heterogeneous (Hete) in a randomized complete block design. Results showed that 9 ppt treatment reduced the fruit weight by 78% and the fruit number by 60% indicating that it's too high for the Washington tomatoes. No significant differences were observed in the shoot dry weight, fruit weight, and fruit number between the Homo and Hete treatments at 4.5 ppt and 9 ppt. The second study used ‘Favorita’ cherry tomatoes to investigate salinity stress in a heterogeneous split-root system. Four treatments were evaluated: a control (0 ppt Homo), and heterogeneous treatments with salinity levels of 0 ppt (0 ppt Hete), 4 ppt (4 ppt Hete), and 6 ppt (6 ppt Hete). The sensory analysis showed consumer preference for either the 0 ppt Hete or 6 ppt Hete treatment and that heterogenous split-root improved the fruit sweetness. Future studies will use shrimp aquaculture effluent, study the feasibility of the split-root system for commercial production, and use electronic nose to further understand consumer preferences
Understanding 40Ar/39Ar Age Variations in Potassium Feldspars from Low-Sulfidation Epithermal Systems in the Miocene Yellowstone Hotspot
Get PDFThe inception of the Yellowstone hotspot resulted in the Columbia River Large Igneous Province (LIP), Mid-Miocene magmatism in western North America, and numerous epithermal Au-Ag deposits in the Oregon-Idaho-Nevada region. 40Ar/39Ar ages of hydrothermal K-feldspars in Au-Ag bearing veins (commonly referred to as ‘adularia’) are useful in understanding the relationship of mineralization to the broader regional magmatic evolution and assisting in targeting exploration and mine development efforts. Although they seem ‘ideal’ to date, and they are highly radiogenic and yield precise ages, 40Ar/39Ar analyses for adularia from the Trade Dollar Mine (Silver City District (SCD), Idaho) and the Jumbo Mine (Nevada) yield ages ranging from 16.27 ±0.11 to 15.79±0.02 Ma, and 16.86±0.13 to 16.15±0.07 Ma respectively. These ages are notably younger than the regional volcanic rocks - and ages for individual crystals from single hand-samples were found to vary by up to ~ 0.7 Ma. These age dates could indicate a remarkably long-lived system, with episodic precipitation of adularia. However, it is more likely that these intercrystalline variations in adularia ages are created by varying diffusive properties between adularia crystals, in combination with episodic precipitation of adularia. X-ray diffraction (XRD) data indicate adularia in the SCD, and the Jumbo Mine are high sanidine (face-centered monoclinic, C2m), suggesting rapid crystallization. Rapid crystallization would prevent the ordering of Al into its preferred T1o site and generate defects in the crystal lattice. Fluid inclusion homogenization temperatures from the SCD range from 180-285°C (Halsor et al., 1988; Aseto, 2012), at or above the calculated closure temperatures (200-266°C) for adularia from the Trade Dollar Mine. This means that upon crystallization, the adularia crystals were partially open systems that lost some radiogenic 40Ar. The range of 40Ar/39Ar closure temperatures are interpreted to be created by effective diffusion dimensions that vary from crystal to crystal. These varying effective diffusion dimensions are likely due to the rapid precipitation of adularia from solution, generating lattice vacancies, and linear and planar defects. This study concludes that 40Ar/39Ar ages reflect the age at which the individual crystal cooled past its respective closure temperature, and not the Au-Ag mineralization age
Towards understanding computer vision system
No full textIn the realm of machine learning and deep neural networks, despite the significant strides made across diverse applications, the understanding and interpretation of these models, particularly under adversarial conditions and in the context of large-scale, multimodal frameworks, remain areas ripe for exploration. This thesis undertakes a detailed exploration of the biases inherent in standard and adversarially trained convolutional neural networks (CNNs). Our findings reveal a pronounced texture bias in standard CNNs, whereas their adversarially trained counterparts predominantly leverage shape cues, a distinction underscored by cue conflict experiments. Through a meticulous neuron-level analysis employing NetDissect, we observe a marked increase in the monotonicity of neurons within robust networks, suggesting a fundamental shift in their information-processing characteristics.
Building on the insights gleaned from our investigation into CNNs, we delve into the domain of large-scale foundation models, where we introduce gScoreCAM, an innovative visualization technique designed to illuminate the focal points of interest within images for OpenAI's CLIP, marrying high performance with unparalleled computational efficiency, achieving a significant leap over existing methods by 8 to 10 times in speed. However, recognizing the limitations of post-hoc explanation methods regarding their reliability and fidelity, we propose the Part-based Image Classifier with an Explainable and Editable Language Bottleneck (PEEB). PEEB represents a paradigm shift towards self-explainable AI frameworks, offering a unique layer of user controllability that enhances trustworthiness by enabling intuitive and transparent explanations directly during inference. This innovation is supported by introducing the Bird-11K and Dog-160 datasets, specifically curated to advance the development of part-based self-explanatory models.
This thesis's contributions illuminate the underlying biases and operational nuances of adversarially trained CNNs while simultaneously pioneering advancements in the explainability and interpretability of complex, large-scale models. By introducing PEEB, complemented by gScoreCAM, we unveil novel pathways to understanding these intricate systems and empower users with a measure of control and transparency previously unattainable, heralding a new era of trust and clarity in artificial intelligence
Effects of Cell Number, Host, and Timing of Injection on Efficiency of Xenogen Production in Ictalurid Catfish
Get PDFXenogenesis is a reproduction technology that has been identified for hybrid catfish (♀ channel catfish, Ictalurus punctatus × ♂ blue catfish, I. furcatus) embryo production. The xenogeneic process can be accomplished by transplanting primordial germ cells (PGCs), spermatogonial stem cells (SSCs), or oogonial stem cells (OSCs), derived from a donor diploid fish into sterile recipients, which then enables the recipient fish to produce donor-derived gametes. The most widely researched form of xenogenesis for the hybrid catfish industry involves transplanting undifferentiated blue catfish cells into triploid channel catfish surrogates. However, there is potential for further technological advancement, particularly as efforts to increase sustainability and efficiency within the U.S. catfish industry continue. Therefore, several experiments were conducted to enhance the efficiency of hybrid catfish embryo production through xenogenesis.
The primary objectives of this thesis were to assess donor cell quantities and explore surrogate species options, The first study aimed to determine whether 80,000 or 100,000 blue catfish cells per fry impacted rates of xenogenesis in surrogate channel catfish. It was identified that 100,000 cells per fry did increase both proliferation and colonization of donor cells in surrogates. The second study also aimed to determine whether 80,000 or 100,000 cells per fry impacted xenogen output, but white catfish (Ameiurus catus) surrogates were used along with both blue catfish and channel catfish donor cells, respectfully. It was identified that the white catfish is a suitable surrogate for hybrid catfish xenogen production, 100,000 cells per fry does lead to increased cell colonization, and no donor species was superior to the other. The third study assessed the feasibility of utilizing the common carp (Cyprinus carpio) as a blue catfish sperm surrogate for hybrid catfish production implications. Common carp accepted undifferentiated blue catfish cells, which migrated to and colonized the anal fin, muscle, pectoral fin, and gonad. Donor cells did not migrate to the eye, liver, intestine, or heart. Overall, these findings will enhance the efficiency of germ cell transplantation for commercial-scale hybrid catfish production
Examining the Effects of Nostalgia on Authenticity, Empathy, and Meaning in Life Among Counseling Students
No full textThis study examined the effects of nostalgia, a bittersweet emotion that is felt as a person reminisces on cherished autobiographical memories on master’s-level counseling students’ authenticity, empathy, and perceptions of meaning in life. Previous research has shown that nostalgia has self, social, and existential capacities. In this respect, previous studies have reported that nostalgia can promote authenticity, empathy, and meaning in life. Focusing on these objectives, this online research study randomly assigned 132 master’s-level counseling students from CACREP-accredited programs across the U.S. to either a nostalgia group or an ordinary memories group. To induce nostalgia, the “The Event Reflection Task” was used, in which participants in the nostalgia group were asked to reflect and briefly write about a nostalgic memory, while participants in the ordinary memories group were asked to do so in connection with an ordinary memory. Following a manipulation check, in which participants in the nostalgia group reportedly felt more nostalgic than those in the ordinary memories group, all participants were asked to complete the Authenticity Scale, the Questionnaire of Cognitive and Affective Empathy, and the Meaning in Life Questionnaire. One-way ANOVA tests showed there were no significant differences in ratings of authenticity, empathy, and meaning in life between the nostalgia and the ordinary memory groups. This study’s findings contribute to the counselor education literature and provide insightful implications for future research on nostalgia within the counseling profession