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Student Experiences of an Adventure Therapy Mountain Bike Program During the COVID-19 Pandemic
Get PDFA mountain bike program was designed and adapted for the school setting with middle school-aged students during 2020, amid the COVID-19 pandemic. Two mountain bike groups were offered to facilitate training and development of mountain bike knowledge and skills: one group with integrated Adventure Therapy components to facilitate a therapeutic process and the other group without a therapeutic debriefing process. Forty-one students participated in the program after being randomly assigned to one of two groups. An exploratory qualitative analysis revealed that the pandemic negatively impacted participants’ wellbeing and academics, leading to increased isolation and decreased motivation, while the mountain bike program increased their focus, competency, physical and mental wellbeing, and connection to the environment. It appears the mountain bike program served as a protective factor for participants. Implications for professionals and researchers are discussed.YesThis is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Adventure Education and Outdoor Learning on July 13, 2022, available at: https://www.tandfonline.com/doi/10.1080/14729679.2022.2100430
2022-23 budget.
Get PDFThe University of Central Oklahoma submits its budget for the upcoming fiscal year to the Oklahoma State Regents for Higher Education for final approval. This document is a copy of the approved budget for FY23
New applications of molybdenum (VI) catalyzed oxygen atom transfer reactions
No full textThe chemistry of dioxomolybdenum coordination complexes has been deeply investigated as a model for molybdoenzyme structure and activity, as well as for non-biological chemical applications. In this work, we present investigation into new applications of dioxomolybdenum reactivity and the mechanisms thereof. Chapter 1 gives a brief summary of metal oxo bonding structure, the reactivity of molybdoenzymes and synthetic molybdenum complexes, oxidative kinetic resolutions, metal-dioxygen complexes, and catalytic oxidation of thiols.
Chapter 2 presents the use of a series of chiral dioxomolybdenum (VI) Schiff-base salen complexes as catalysts for the oxidative kinetic resolution of the P-chiral monophosphine, methylphenyl-tert-butyl phosphine. The studied complexes are shown to yield the chiral phosphine oxide in low to moderate enantiomeric excess (0-35% e.e.) employing pyridine N-oxide as the stoichiometric oxygen atom source. Use of a para-nitro substituent on the ligand salicylimine ring is found to increase catalyst activity, and enantioselectivity of the reaction is found to be controlled by steric bulk at the salen ortho-position. Density Functional Theory (DFT) study of the reaction finds the stereochemically-defining step is the O-transfer transition state involving nucleophilic attack of the phosphine on an oxo-group of the chiral LMoO2 complex.
Chapter 3 reports the catalytic oxidation of phosphines by Schiff-base complexes of dioxomolybdenum under aerobic conditions. The activity of the complexes toward aerobic oxidation of phosphines is found to be the same as with pyridine N-oxide, with the presence of a para-nitro substituent greatly increasing the rate of oxidation. DFT studies are carried out to determine the mechanism of coordination and activation of dioxygen towards oxygen atom transfer, and to determine which of the available oxygen atom transfer pathways is most favorable for the oxidation of phosphines. Transfer of the oxo moiety is found to be most favorable, and the dioxo complex is regenerated through an unusual cleavage of the peroxo group. A computational investigation of oxygen atom transfer to sulfoxides and their lack of reactivity towards oxidation by dioxomolybdenum complexes is also reported.
Chapter 4 extends the reactivity of Schiff-base dioxomolybdenum complexes to include the oxidation of thiols to disulfides under base-free conditions. This reactivity is found to encompass alkyl, benzyl, aryl, and amino acid-derived thiols. Alkyl and benzyl thiols are found to be oxidized to two primary products, of which the disulfide is the major (60-80% yield). The secondary products are found to differ due to substrate effects, with benzyl mercaptan oxidized to benzyl trisulfide and dodecane thiol oxidized to the previously unreported dodecane sulfenic anhydride. The selectivity of this oxidation toward formation of disulfide products is found to increase with addition of base, and variation of catalyst electronics (salen para-substituent = NO2, H, OMe) shows significant rate and product distribution effects. DFT study of possible reaction intermediates suggest this oxidation proceeds initially via a hydrogen atom transfer process forming a thiyl radical and a molybdenum (V) oxo-hydroxyl species. Disproportionation of two molecules of the molybdenum (V) species forms one dioxomolybdenum (VI) complex, one oxomolybdenum (IV) complex, and a molecule of water. Mechanistic pathways are suggested for formation of disulfide, trisulfide, and sulfenic acid products
Digging Deep into the Summer Activities at Bull Creek (34BV176): A Late Paleoindian Site in the Southern Plains
No full textThe Bull Creek site (34BV176), located along a tributary of the Beaver River in the Oklahoma Panhandle, belongs to a short list of late Paleoindian open-habitation camps. Events at Bull Creek are superimposed on one another. No clear refuse area (such as a midden, palimpsest, or dump) is evident, leaving the idea that the entirety of Bull Creek is in its’ original context, abandoned on at least three separate occasions. To better understand the activities resulting in the artifactual and feature components of the archaeological record, I relied on the methods of ring analysis, the refit analysis of bone artifacts, animal protein residue and plant/starch analysis on lithic artifacts, 3D rendering, and experimental butchering. The spatial distribution of the remains from a single bison were plotted and investigated in relationship with other site materials, including a hearth, a lithic hammerstone/anvil couplet, and an isolated bone tool, resulting in the conclusion that site materials identify the animal butchering, animal processing, and plant processing around a central hearth feature
Stable Atmospheric Boundary Layer Turbulence: Insights from Uncrewed Aircraft System Observations and Large-Eddy Simulations
Get PDFThe physical processes governing stable atmospheric boundary layer (SBL) dynamics have significant societal impacts ranging from pollution dispersion and wind energy production to polar sea ice loss. For decades, SBL turbulence has proven challenging to measure, parameterize, simulate, and interpret for a variety of reasons. For example, turbulence intensity in the SBL is often orders of magnitude smaller than in the convective boundary layer as thermal stratification suppresses vertical motions. As atmospheric stability increases, turbulence can also become intermittent in space and time, resulting in poor convergence of temporally-averaged turbulence statistics. Characteristic turbulent motions within the SBL can also be considerably smaller than the grid spacings employed by operational numerical weather prediction (NWP) models. These NWP models therefore need to parameterize turbulent energy exchange within the SBL, which can result in significant errors in near-surface temperature and wind speed forecasts due to the imperfect nature of parameterization schemes. It has been shown that improvements in SBL forecasting skill have been hindered by a relative lack in knowledge of fundamental SBL processes, which in turn is partially due to a dearth in routine and spatially dense thermodynamic and kinematic observations within the SBL. To address this so-called data gap, uncrewed aircraft systems (UAS) are proving the ability to reliably sample the atmospheric boundary layer (ABL), offering a new perspective for understanding the SBL. Moreover, continual computational advances have enabled the use of large-eddy simulations (LES) to simulate the atmosphere at ever-smaller scales. This dissertation therefore seeks to synergize UAS observations and large-eddy simulations to explore the underlying processes governing SBL dynamics.
In the first component of this dissertation, we explore the potential of a new method for the estimation of profiles of turbulence statistics in the SBL. By applying gradient-based scaling to multicopter UAS profiles of temperature and wind, sampled over sea ice during the 2018 Innovative Strategies for Observations in the Arctic Atmospheric Boundary Layer (ISOBAR18) field campaign, turbulence profiles can be derived. We first validate this method by scaling turbulence observations from three levels on a 10-m mast with the corresponding scaling parameters, and comparing the resulting non-dimensional parameters to the semi-empirical similarity functions proposed for this scaling framework. The scaled data of turbulent fluxes and variances from the three levels collapse to their corresponding similarity functions.
After the successful validation, we estimate turbulence statistics from UAS profiles by computing profiles of the gradient Richardson number to which we then apply the similarity functions. These UAS profiles are processed from raw time series data by applying low-pass filters, time-response corrections, altitude corrections, and temporal averaging across successive flights. We present three case studies covering a broad range of SBL conditions to demonstrate the validity of this approach. Comparisons against turbulence statistics from the 10-m mast and a sodar indicate the broad agreement and physically meaningful results of this method. Successful implementation of this method thus offers a powerful diagnostic tool that requires only a multicopter UAS with a simple thermodynamic sensor payload. This ability to estimate vertical profiles of turbulent parameters that were otherwise unobtainable with traditional ground-based observations can be invaluable, e.g., for NWP verification studies within the SBL.
As UAS continue to be recognized as a robust observational platform, it is becoming increasingly important to establish a baseline framework towards understanding the extent to which vertical profiles from UAS can represent larger-scale SBL flows. This representativeness can be quantified by evaluating the magnitude of random errors for a given observation, which arise due to averaging a signal across an insufficient amount of independent samples for a statistical quantity to converge towards its true underlying ensemble value. Moreover, the LES technique can be a powerful tool for simulating SBL turbulence in space and time while varying thermal stratification to contextualize observations by UASs. The second component of this dissertation therefore seeks to quantify the representativeness of observations from UAS profiles and eddy-covariance observations within the SBL by performing a random error analysis using a suite of six large eddy simulations for a wide range of stabilities. For each experiment, we estimate relative random errors using the relaxed filtering method of Dias et al. (Boundary-Layer Meteorology, 2018, Vol. 168, 387--416) for first- and second-order moments as functions of height and averaging time. We show that the random errors can be of the same order of magnitude as other errors due to e.g. instrument bias and dynamic response, especially close to the surface. For these reasons, we recommend coupling UAS observations with other ground based instruments as well as dynamically adjusting the UAS vertical ascent rate to account for how errors change with height and stability.
In the first component of this dissertation, we consider only observations by UAS in the Arctic SBL, and in the second component we further explore the representativeness of UAS observations within idealized SBLs with LES. To conclude this dissertation, in the third component we employ only a series of eight large-eddy simulations to investigate fundamental processes within stably-stratified wall-bounded turbulent flows from the perspective of coherent structures. To date, a growing body of literature has documented the existence and impacts of so-called large- and very-large-scale motions within wall-bounded turbulent flows under neutral and convective thermal stratification. Large- and very-large-scale motions have been attributed to modulating turbulence intensity near the wall, and properly characterizing their contributions to ABL turbulence may lead to improvements in NWP forecast skill. In the context of the SBL, however, the examination of such coherent structures has garnered relatively little attention. Stable stratification limits vertical transport and turbulent mixing within flows, which makes it unclear whether previous findings on coherent structures under unstable and neutral stratification are applicable to the SBL. Moreover, mesoscale processes can obscure the underlying physics of stably-stratified flows when collecting observations in the SBL. In this third component, we investigate the existence and characteristics of coherent structures within the SBL with a wide range of statistical and spectral analyses. A quadrant analysis of turbulent transport efficiencies (the ratio of net fluxes to their respective downgradient components) demonstrates dependencies on both stability and height above ground, which may be related to morphological differences in the coherent structures under increasing stability. Physical mechanisms responsible for these differences are explored through analyses of spectrograms, linear coherence spectra, amplitude modulation coefficients, and conditional sampling for a variety of first- and second-order turbulent moments. Results indicate the presence of coherent structures at near-neutral stability that diminish with increasing stable stratification. Stable stratification was found to suppress large eddies, thereby limiting any inner-outer scale interactions
The problems of fit indices on replicated SEM studies
Get PDFThere has been a research gap in examining fit indices under the context of reproducing the result of structural equation modeling (SEM) since a replication attempt revisited not many SEM studies. Two simulation studies were conducted to examine the distribution of fit indices of SEM on replicated samples. The first simulation chose three examples from social science literature to mimic replication attempts and found that the distribution of some indices shifted away from the original value. Specifically, the fit indices that use chi-square in their formulation consistently indicated a worse fit between the model and the data in a large proportion of replication attempts. Meanwhile, relative fit indices that use log-likelihood values such as AIC and BIC were less affected by replication, showing the distribution of replicated indices centered around the value from the original sample. The chi-squared family of fit indices showed an inferior fit than the original when one tries to replicate data using the observed moment matrix, even if the model fitted well to the original data. Using a baseline model log-likelihood, a new likelihood ratio LR0 that resists the fit-worsening effect of replications is suggested. The second simulation that varied model specification, model complexity, and sample size confirmed the finding from the first study and examined the performance of the LR0. The new likelihood ratio was much less affected by replication than the standard likelihood ratio, but its interpretability was limited. The diminishing effect on fit indices in replicated samples implies that one should interpret them carefully
Is Iron Status an Additional Barrier to Smoking Cessation in Females? An ERP Analysis.
Get PDFIt has been well-established that females achieve lower cessation rates than males in traditional smoking cessation interventions. Research suggests that iron status variations (i.e. deficiency) are common in females. Iron status variations are known to alter dopamine (DA) pathways and learning ability involved in reward processing and addiction. This suggests a mediation model which may partially explain the sex differences in cessation rates wherein iron status predicts abstinence directly and indirectly via changes to reward processing. The current study enrolled 54 females at the onset of smoking cessation intervention and measured cognitive task behavior with concurrent electroencephalography (EEG). In addition, assays were run to extract iron biomarkers from a blood sample. ERP components known to be sensitive to reward learning were extracted from the EEG data. Task behavior was quantified in terms of accuracy and/or reaction time. Lastly, blink rates were extracted from the EEG to act as a proxy for dopaminergic status. After imputing missing data and using a Bayesian variable selection framework to select a final set of mediators, a Generalized Structured Component Analysis was employed to test three mediation models. Results revealed that iron status, task behavior, dopamine status, and neural components accounted for 1/3 of the variance in smoking cessation. These outcomes suggest that iron status may play a role in success or failure in achieving cessation during a quit attempt. These results may have implications for future smoking cessation intervention standards of care
