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On flexible and efficient new econometric approaches for choice data analysis
Get PDFThe theory and application of choice models have progressed by leaps and bounds in several directions over the last two to three decades. This dissertation adds to this expanding body of literature by contributing to, and elevating, the state-of-the-art in choice modeling through the introduction of more flexible model structures, newer dependent variable forms, efficient estimation procedures, and contextual empirical applications. Our first focus is on multivariate dependent outcome models. There is growing interest in multivariate mixed dependent outcome models that include a mixture of different kinds of discrete and continuous variables. Within the transportation literature, factorization-based approaches have received substantial attention in accounting for the jointness of such mixed dependent outcomes. These factorization approaches allow for a parsimonious estimation of the covariance matrix through the use of latent factors. However, there are two important assumptions in all such earlier mixed dependent outcome models: (i) marginal normality of unobserved factors (latent constructs) that generate jointness among the main outcome variables of interest, and (ii) independence between the unobserved factors (latent constructs) and the propensity equations underlying the main outcomes of interest. In our current effort, we simultaneously relax both these assumptions and develop a flexible Generalized Heterogeneous Data Model (GHDM) for mixed data modeling. To do so, we use the Yeo-Johnson (YJ) transformation (which allows for a single-parameter non-normal to normal transformation) for the unobserved factors (latent constructs) to relax the first assumption, while explicitly allowing these latent constructs to be correlated with the main outcomes (thus, relaxing the second assumption). We demonstrate an application of our proposed model in the context of individuals’ high-density residential neighborhood living choices and monthly bicycling frequency. Next, we individually extend the techniques behind each of the two relaxations undertaken in the previous study in unique directions. First, as an extension of the YJ transformation to multinomial discrete choice models, we propose the use of this transformation to account for non-normal random parameters in a multinomial probit (MNP) setting. Our proposed model, which we call the MNP-YJ model, provides a systematic implicit-Gaussian-copula-based framework to account for non-normality and dependencies across the random coefficients. We utilize this new multinomial model framework to investigate factors impacting commute mode choice in a developing economy. Second, following the flexible GHDM dependency approach, we extend the framework to the consideration of a rank-ordered variable among the main outcomes. Rank-based preference surveys can be exploited to achieve a certain desired precision in choice model estimation with a much smaller sample size, making ranked data surveys more cost-effective than traditional first-choice surveys. From a substantive standpoint, we contribute to the study of land use-transportation relationships by investigating residential location effects on auto-ownership levels and rank-based mode preferences of individuals, within a hypothetical futuristic autonomous vehicle landscape. Owing to the advantage in the efficiency of using a rank-based approach (as opposed to the first-choice approach) in a multinomial choice context, we further focus our efforts on the use of a rank-ordered dependent variable in a spatial model that accounts for the stochastic dependence in choice-making across individuals. Specifically, we propose a methodological framework for a spatial rank-ordered probit model (SROP) that accommodates both spatial lag effects as well as spatial drift effects. An application of the proposed model is demonstrated in a travel mode choice ranking experiment among seven alternatives, including autonomous vehicle (AV) private ride-hailing and AV pooled ride-hailing.Civil, Architectural, and Environmental Engineerin
Sources and fate of terrestrial organic matter in Arctic coastal waters
No full textLarge quantities of terrestrially-derived organic matter (OM) are delivered to the Arctic Ocean. This terrestrial OM is an energy subsidy for heterotrophs, supporting secondary marine production, and, if remineralized, releases inorganic nutrients that support primary production. Additionally, this OM may be decomposed to produce greenhouse gases like carbon dioxide and methane, impacting the global carbon cycle. While the land-to-ocean fluxes and bioavailability of riverine OM are relatively well constrained, much less is known about OM from Arctic coastal erosion or coastal groundwater. This work provides novel information about the composition and biodegradability of OM in eroding soils and coastal groundwater along the Alaska Beaufort Sea coast. We found that the geochemical composition of eroding permafrost varies from tundra surface to sea level, related to both the landscape geomorphology and processing within permafrost. Using experiments to measuring carbon dioxide production from bulk soils and permafrost in seawater, as well as biodegradability of dissolved organic carbon (DOC) leached from those soils in seawater, we found that marine-derived OM in late-Pleistocene age permafrost was more bioavailable compared to terrestrial and/or lacustrine OM in Holocene age active layer soils and permafrost. Pairing these experimental data with shoreline loss rates and soil carbon stocks, we show that coastal erosion supplies notable quantities of bioavailable organic carbon to the Alaska Beaufort Sea. We expect erosion to be relatively important during summer when inputs of bioavailable OM from rivers are low. We also compared the composition and biodegradability of DOC in supra-permafrost groundwater to surface waters. Despite being highly aromatic, groundwater DOC was more biodegradable than river DOC. In both groundwater and rivers, biodegradable DOC declined from spring break-up to fall freeze-up. Given the high concentrations of DOC in coastal groundwater, groundwater is potentially an important source of bioavailable OM to nearshore Arctic waters, fueling marine productivity and/or greenhouse gas emissions. These results are particularly relevant as the Arctic is rapidly warming, likely altering the mobilization of terrestrial OM to the Arctic Ocean.Marine Scienc
Artist Diploma Recital (soprano)
No full text10 son I'umile ancella from Adriana Lecouvreur / Cilea, Francesco -- 3 Sonetti del Petrarca, S.270 (Pace non trovo, Benedetto sia 'I giorno, I vidi in terra) / Liszt, Franz -- 3 Browning Songs, op.44 (The Year's at the spring, Ah, love, but a day! I send my heart up to thee!) / Beach, Amy -- 2 Chinese folk songs (Yearning and love, Swan goose) -- Good-Bye! / Tosti, PaoloMusicName of supervisor not provided
Evolution of the voice : vocal production in frogs, bats, and humans
Get PDFThe three chapters of this dissertation examine the evolution of the voice from the four perspectives originally laid out by Nikolaas Tinbergen: ontogeny, mechanism, phylogeny, and adaptive function. Chapter 1 focuses on the development of the larynx in the túngara frog (Physalaemus pustulosus), a neotropical amphibian. By tuning mathematical models with micro-CT-based measurements taken from an ontogenetic series of larynges, we show that male túngara frogs could likely vocalize during a “silent phase” in their development, suggesting that their muteness is facultative and not physically enforced. This result helps to illuminate morphological and behavioral consequences of an interplay of natural and sexual selection. Chapter 2 analyzes morphology, scaling, and constraint in the vocal apparatus of neotropical bats. We used micro-CT imaging and bioacoustics analysis to investigate larynx morphology and allometric scaling in eleven species of neotropical bats across six families. Within the sampled taxa, call acoustics and larynx morphology were strongly constrained by body size. Laryngeal cartilage mineralization patterns appeared to be more determined by phylogenetic structure than taxon-specific differences in echolocation call structure. We also failed to find a systematic relationship between larynx morphology, call structure, and the acquisition of vocal production learning. Overall, our results suggested that strong physical and phylogenetic constraints act on the form and acoustic output of the chiropteran larynx, despite its specializations. In Chapter 3, we measured the acoustic space occupied by human speech, non-linguistic, and musical vocalizations along with the calls of chimpanzees, bonobos, and chacma baboons. We use Mel-frequency cepstral coefficients to create an acoustic space depicting the spectro-temporal features of over 750,000 brief vocal segments. Speech and song occupied significantly less acoustic-feature volume than human non-linguistic vocalizations. In addition, the volumes of speech and song were not statistically different from those of non-human primates. These results suggest that speech was not enabled by an expansion of human vocal range. Anatomical shifts unique to humans may have led to an elaboration of non-linguistic utterances, but learned vocalizations use a surprisingly small fraction of this space.Ecology, Evolution and Behavio
Doctoral thesis recital (piano)
No full text3 unidentified works for piano.MusicName of supervisor not provided
Advanced development of mass spectrometry technologies for intraoperative molecular diagnostics
Get PDFMass spectrometry is well-suited for the analysis of complex biological samples like human tissues because hundreds of molecules can be simultaneously detected and resolved based on differences in their observed mass to charge ratios. Conventional mass spectrometry approaches for biological sample analysis involve an orthogonal front-end chromatographic or ion mobility separation prior to mass analysis to improve confidence in molecular identification. Conventional approaches also rely on some sort of extraction based sample preparation step to enhance the detection of specific molecular classes e.g. lipids, metabolites. This dissertation focuses on an unconventional mass spectrometric approach, namely the direct mass spectrometric analysis of human tissues without any sample preparation or orthogonal front-end separation prior to mass analysis. This approach allows for untargeted molecular profiling of tissue samples in which hundreds of molecules belonging to a variety of molecular classes and can be characterized in near real-time. The molecular profiles of tissues with varying disease states can provide insights into disease pathology and guide the development of new therapies. Mass spectrometry based molecular profiles can also be used in conjunction with predictive modeling and/or machine learning to differentiate disease states and tissue types based on the molecules detected. Although several types of direct mass spectrometry techniques exist, this dissertation exclusively describes advancements in using the MasSpec Pen, a liquid-extraction probe, for the direct mass spectrometry analysis of tissues during surgery. Chapter 2 outlines changes to the design of the MasSpec Pen probe that expanded its utility beyond traditional open-surgery and allowed integration of the probe during minimally invasive robotic surgeries. Chapter 3 describes the implementation of the MasSpec Pen during ovarian cancer surgeries for real-time in vivo and ex vivo molecular analysis of human tissues. Chapter 5 introduces a unique mobile mass spectrometry platform that allows a single orbitrap mass spectrometer to be operated in multiple locations without the need to power down or vent the ultrahigh vacuum system. Chapter 6 describes a hybrid predictive modeling approach in which datasets from an alternative direct mass spectrometry analysis technique, desorption electrospray ionization, are used to create predictive models for the classification of MasSpec Pen molecular profiles. As a whole, this dissertation describes both advancements in mass spectrometry data acquisition during surgery and mass spectrometry based predictive modeling for the disease state classification of human tissues.Chemistr
Doctoral thesis recital (piano)
Get PDFSuite en la mineur (RCT 5), No. 7 "Gavotte et six doubles" (1726/27) / Jean-Philippe Rameau -- Piano sonata no. 28 in A major, op. 101 / Ludwig van Beethoven -- Variations on a theme by Paganini : op. 35 book 1 / Johannes Brahms -- L'islse joyeuse : op. 106 / Claude Debussy.MusicName of supervisor not provided
Effects of aquatic exercise on hemodynamics, cognition, and functional mobility in older adults
Get PDFAging presents various challenges, including declines in cardiovascular function, cognition, and functional mobility. Regular exercise can help mitigate these aging-related health concerns. However, most available research focuses on land-based exercise such as walking and cycling. Unfortunately, adherence to land-based exercise is often low among older adults, particularly those with arthritic pain, functional limitations, or a fear of falls. The aquatic environment has the potential to reduce barriers to exercise, allowing this vulnerable population to benefit from exercise. The overall theme of this dissertation is to investigate the beneficial effects of aquatic exercise on cardiovascular function, cognition, and functional mobility in older adults. The rationale for these projects is to more clearly determine the advantages of aquatic exercise and highlight it as a viable alternative to land-based exercise for improving overall health in older adults. In the first study, a randomized crossover trial compared orthostatic hemodynamics in water versus on land in older adults. Blood pressure and heart rate measurements were collected in sitting and standing before, immediately after, and 2 hours after walking exercise performed on land and in water. The primary finding revealed a 86% lower occurrence of orthostatic hypotension episodes in the water. Additionally, immersion in water resulted in an increase in mean arterial pressure and a decrease in heart rate, and this effect persisted for at least 10 minutes after emerging from the water. This hemodynamic response to orthostatic stress when in the water could be beneficial for individuals with orthostatic hypotension. In the second study, the effects of an 8-week aquatic cognitive-motor exercise program were evaluated in older adults using a randomized controlled trial. The intervention yielded clinically meaningful improvements in systolic blood pressure and pulse pressure compared to a control group (usual routine) that did not experience a significant change in blood pressure. Furthermore, the aquatic exercise intervention showed moderate to large beneficial effects on cognition, single and dual-task gait, and functional mobility, whereas only small to negligible effects were observed in the control group. Taken together, the findings from this dissertation highlight the benefits of aquatic exercise in improving the overall health of older adults.Kinesiology and Health Educatio
Microwave heating for the synthesis of precious metal-based nanoparticles for gas- and liquid-phase reduction reactions
Get PDFMain goal of this overall research is the design and synthesis of highly active precious-metal based heterogeneous catalysts. The underlying strategy is to attain cost effectiveness and better catalytic performance by nanoscale dilution of expensive metals such as Rh, Pd, Pt, & Au using readily available and cheaper metals (Cu, Ag, etc.). Such hetero-metal mixing usually lead in advantageous synergy effects and yield superior nanoparticle (NP)-catalysts. A crucial aspect of this research is microwave irradiation (μwI) which unlike conventional heating (CvH), strongly couples to polar solvents, ionic metal precursors and therefore may provide access to classically immiscible bimetallic systems. Surface reactivities of our hetero-metallic NPs have been successfully used as vapor-phase probes to derive reactivity and kinetic information which in turn is directly compared with collaborative DFT calculations. Specifically, synthesis of PdₓAu₁₀₀₋ₓ alloy NPs in wide range of compositions have been carried out to distinguish efficacy of the two heating methods (μwI & CvH). Composition dependent catalytic tunability was experimentally observed in both gas-phase hydrogenation reaction, and aqueous-phase nitrite reduction using PdₓAu₁₀₀₋ₓ alloy NPs. This observation matched reasonably well with theoretical calculations. In a separate project, scalability issues associated with small-scale batch reactions are addressed using flow methods to synthesize Rh NPs under μwI. Mechanistic insight into distinct morphologies of Rh NPs obtained using single-, and two-phase flow methods is attained and structural differences are probed by model hydrogenation catalysis. In another study, Cu-containing bimetallic NP systems (PdCu & RhCu) are currently being investigated to further address the cost factor while retaining superior catalytic activity. Moreover, highly atom-efficient Ag-based nanocages are also synthesized under μwI. Detailed investigation into the formation mechanism of such exciting and unique nanostructures are currently underway. Several characterization techniques such as PXRD, UV-vis, FTIR, XPS, TEM, STEM-EDX, ICP (-MS & -OES), etc. are routinely employed to fully delineate research described herein.Chemistr
Progress in the Development of a Science and Engineering Library Over a Twenty-Five-Year Period, 1990 Through 2015
No full textAs part of its 25-year anniversary celebration, Rodgers Library for Science and Engineering at The University of Alabama developed a poster highlighting changes in collections, services, and facilities which improved instruction and research among students and faculty served by the library. At the beginning of this period, attention shifted to digital libraries, as journals, indexes, and books that were previously available in print became accessible in digital format. More than one hundred software applications became accessible through upgraded desktop computers. Facilities saw considerable transformation, too. Collaborative spaces for students improved with the addition of more group study rooms. Outreach and instruction became a priority during this time.Informatio