Cognitive content and vulnerabilities to anxiety in later life

Ayers, Catherine R George Mason University 2005 해외박사(DDOD)

Research on the unique characteristics of anxiety and its corresponding consequences in older adulthood is only in the beginning stages of scientific examination (e.g. Salzman & Lebowitz, 1991). Isolating the cognitive components of anxiety in older adults and examining the interrelationships with other factors, such as cognitive hardiness and looming vulnerability, is one possible step toward understanding this phenomenon. This study examined: (1) the unique cognitions that are predictive of anxiety; (2) their relationship with validated constructs of anxiety, such as generalized anxiety and the looming maladaptive style, and (3) how various cognitive styles, such as cognitive hardiness, interact to prevent or maintain anxiety in an older adult population. The sample consisted of 177 (age range 56--100) high functioning older adults who reside in a continuing care retirement facility in Northern Virginia (N = 94) and another sample of community dwelling seniors who take courses through the Learning in Retirement Institute at George Mason University (N = 83). A sample of undergraduates (N = 75) was also recruited to compare age related differences in anxiety cognitions. Results from the present study indicate that (1) older adults demonstrate a unique pattern of anxiety cognitions, distinct from young and middle aged adults (age range 18--50); (2) anxiety and depression are highly interrelated in the elderly, (3) certain cognitions, particularly escalating loss of control cognitions, may be more useful in pinpointing anxiety in healthy older age groups; (4) the looming maladaptive style is a useful construct that provides information on vulnerability to anxiety in later life and (5) cognitive hardiness does not serve as a protective factor against anxiety, physical health consequences, and negative life events.

Variational principles for describing chemical reactions

Ayers, Paul Woodson The University of North Carolina at Chapel Hill 2001 해외박사(DDOD)

Of paramount importance to chemistry are what Coulson called “primitive patterns of understanding”: simple concepts that subsume many seemingly disparate chemical phenomenon. Density-functional theory has proved particularly apt for the tasks of obtaining new chemical concepts and elucidating the theoretical basis for existing chemical principles. Here, perturbation series in the electron density and external potential and the variational principle for the energy are used to derive molecular reactivity indicators and stability principles. Starting with the foundations of wave function-based quantum mechanics, the first chapter of the dissertation derives the key theorems and methods of density-functional theory and provides motivation for using density-functional theory as a tool for studying chemical reactions. Starting from this point, the next five chapters show how functional Taylor series (typically truncated at second order) and variational theorems for the total energy of a molecule can be used to derive conceptual tools for understanding chemical reactivity. Chapter two deals specifically with perturbations of the electron density and derives variational principles for the Fukui function and local softness; these indices are especially appropriate for describing chemical reactions between Lewis acids and bases. The physical significance of the maximum hardness principle is also elucidated. Chapter three uses perturbation series in the external potential to derive reactivity indicators based on the external potential, among them a site reactivity index for cationic and anionic reagents, the proton hardness, and indices for the lability and stability of a molecular structure; these reactivity indices are especially appropriate for describing chemical reactions between Brönsted-Lowry acids and bases. In chapter four, strategies for computing the reactivity indicators of chapters two and three are explored. Chapter five generalizes the development of chapter two to condensed reactivity indices, with particular emphasis on the problematic issue of whether the condensed Fukui function can be negative. Finally, chapter six proposes methods for treating excited states in density-functional theory, with particular emphasis on excited state Fukui functions and chemical potentials.

Linking individual biological outcomes to resource use

Ayers, Christopher Ryan Mississippi State University 2014 해외박사(DDOD)

Minimum resource requirements support population persistence; however, ecologists and conservationists often want to identify factors that improve biological outcomes of animals. The population-level approach common in wildlife-resource studies limits our ability to draw inferences about the importance of resources and other factors by failing to link them with individual fitness. Measuring individual-based biological outcomes and resource use helps determine variation in mechanistic relationships between animal fitness and behavior. I suggest using direct metrics of resource use such as food consumption and distance traveled, to avoid errors with estimating resource availability. I summarize these concepts in an analytical framework for modeling relationships between resource use and fitness to guide readers toward effective study designs. I also describe constraints on an animal's ability to use resources freely, which must be considered when modeling these relationships to account for additional sources of variation in biological outcomes. I investigated effects of resource use on body condition, survival, and reproduction using field data from four species of vertebrates. I found that using multiple predictor metrics to model biological outcomes allows comparison between factors affecting fitness. In general, factors more closely relating to energetics (e.g., movement pattern or distance traveled) were more useful predictors of animal outcome than metrics of habitat use or selection. Management and conservation efficiency can be improved by focusing efforts on preventing detrimental risks and threats, and supporting less stressful access to beneficial resources rather than supporting average population habitat use without consideration of biological outcomes. Improving the study of ecology depends in part on our efforts to seek finer-scaled mechanistic observations of relationships among individual organism behavior, resource use, and biological outcomes that improve our understanding of population-level resource ecology. Melding current techniques to obtain detailed evidence of how habitat is used at an individual level will allow us to relate resources to fitness for more efficiently understanding an animal's ecology and improving conservation and control of populations. While we will continue to manage for populations, we must not lose sight of the individual variation that drives natural selection if we want to fully understand variation in resource-outcome relationships.

Structural damage diagnostics via wave propagation-based filtering techniques

Ayers, James T., III Georgia Institute of Technology 2010 해외박사(DDOD)

Structural health monitoring (SHM) of aerospace components is a rapidly emerging field due in part to commercial and military transport vehicles remaining in operation beyond their designed life cycles. Damage detection strategies are sought that provide real-time information of the structure's integrity. One approach that has shown promise to accurately identify and quantify structural defects is based on guided ultrasonic wave (GUW) inspections, where low amplitude attenuation properties allow for long range and large specimen evaluation. One drawback to GUWs is that they exhibit a complex multi-modal response, such that each frequency corresponds to at least two excited modes, and thus intelligent signal processing is required for even the simplest of structures. In addition, GUWs are dispersive, whereby the wave velocity is a function of frequency, and the shape of the wave packet changes over the spatial domain, requiring sophisticated detection algorithms. Moreover, existing damage quantification measures are typically formulated as a comparison of the damaged to undamaged response, which has proven to be highly sensitive to changes in environment, and therefore often unreliable. As a response to these challenges inherent to GUW inspections, this research develops techniques to locate and estimate the severity of the damage. Specifically, a phase gradient based localization algorithm is introduced to identify the defect position independent of excitation frequency and damage size. Mode separation through the filtering technique is central in isolating and extracting single mode components, such as reflected, converted, and transmitted modes that may arise from the incident wave impacting a damage. Spatially-integrated single and multiple component mode coefficients are also formulated with the intent to better characterize wave reflections and conversions and to increase the signal to noise ratios. The techniques are applied to damaged isotropic finite element plate models and experimental data obtained from Scanning Laser Doppler Vibrometry tests. Numerical and experimental parametric studies are conducted, and the current strengths and weaknesses of the proposed approaches are discussed. In particular, limitations to the damage profiling characterization are shown for low ultrasonic frequency regimes, whereas the multiple component mode conversion coefficients provide excellent noise mitigation. Multiple component estimation relies on an experimental technique developed for the estimation of Lamb wave polarization using a 1D Laser Vibrometer. Lastly, suggestions are made to apply the techniques to more structurally complex geometries.

Peer-Mentoring for New International Students: A Study on Utilizing a Peer-Mentoring Program to Assist New Students Experiencing Acculturation

Ayers, Aaron Dee ProQuest Dissertations & Theses Arizona State Univ 2019 해외박사(DDOD)

The purpose of this mixed-methods action research study was to discover the hindrances and apply new innovative ideas to the problematic stages of student acclimatization and acculturation to an American education and Taiwanese host culture. The goal was to improve academic success during the initial first year, improve the acclimatization process, and stimulate the acculturation process.The study applied a mixed-methods approach. Four new foreign students participated in a 12-week innovation. This innovation consisted of establishing a protocol for school staff, creating and implementing a student-led Welcoming Committee, training at the beginning of the school year, establishing guidelines and expectations for participating Welcoming Committee members, assigning peer mentors to new students, and providing opportunities for socializing and meeting people. The participants took pre and post cultural self-efficacy tests. In addition, qualitative data was collected from the interviews of the four participants. The new foreign students showed an increase in cultural self-efficacy from the beginning of the innovation to the conclusion of it. Findings of this study found that students used past experiences in creating initial perceptions, these perceptions changed after interactions with the Welcoming Committee, ample assistance was given to the new foreign students throughout the innovation, and Welcoming Committee members were relied on to make initial contact with others due to initial difficulties in this area.

Optimizing Processor Architectures for Warehouse-scale Computers

Ayers, Grant Edward ProQuest Dissertations & Theses Stanford Universit 2019 해외박사(DDOD)

Does Genetic Conflict Contribute to Pregnancy Complications and Postpartum Health and Behavior?

Ayers, Jessica D ProQuest Dissertations & Theses Arizona State Univ 2022 해외박사(DDOD)

Pregnancy is often described as one of the most cooperative ventures that a woman can experience in her lifetime. But when one considers the biological changes that occur during pregnancy, it becomes clear that pregnancy is not as cooperative as it seems on the surface. The current research uses a genetic conflict framework to predict how underlying conflict between mother and fetus over resource transfers is expected to alter eating behavior and food preferences, and how these changes in eating behavior and preferences should then be associated with certain pregnancy complications. Across two studies, women who had recently had a baby (Study 1) or were currently pregnant (Study 2) recalled changes in their eating behavior during pregnancy as well as any pregnancy complications they experienced during that pregnancy. Providing partial support for the hypotheses, women who reported increased vomiting in response to maternal-favoring foods were more likely to experience preeclampsia during pregnancy. In addition, the results provided preliminary evidence that changes in pregnancy eating behavior were associated with an increased the likelihood of experiencing high blood pressure, gestational diabetes, and infections during pregnancy. Taken together, these studies show that the framework of genetic conflict makes testable predictions about the relationship between eating behavior in pregnancy and pregnancy complications, and that several pregnancy complications that are relevant to genetic conflict (high blood pressure, pre-eclampsia, gestational diabetes, and infection) are associated with changes in eating behavior in pregnancy. Future research should continue to investigate how genetic conflict influences the relationships between pregnancy eating behavior, pregnancy complications, and how these associations impact postpartum health.

An experimental cross section for the hydrogen atom, hydrogen molecule exchange reaction as a function of angle and energy

Ayers, James David Stanford University 2003 해외박사(DDOD)

Being the simplest bimolecular reactions of neutrals, the hydrogen atom, hydrogen molecule exchange reaction has received detailed experimental and theoretical treatment. We report an experimental study of an isotopic variant of the reaction and compare the results to theoretical calculations. The reaction H + D₂ → HD(ν<super>′</super> = 3, <italic>j</italic><super> ′</super> = 0) + D is studied at nine different collision energies between 1.39 and 1.85 eV using the PHOTOLOC technique (PHOTOinitiated reaction analyzed with the Law Of Cosines). Lasers are used both to photoinitiate the reaction via photolysis of HBr and detect HD(ν<super>′</super> = 3, <italic> j</italic><super>′</super> = 0) products via (2 + 1) resonance-enhanced multiphoton ionization (REMPI). Differential cross sections (DCS) show a forward-scattered feature that changes intensity as the collision energy is increased. A peak in the relative ratio of forward to backward scattering is observed at approximately 1.64 eV collision energy. The integral cross section is measured between 1.49 and 1.85 eV. Several experimental modifications are required, including the addition of another laser beamtrain to quantify hydrogen atom generation using (2 + 1) REMPI. Results indicate that the integral cross section changes little over this energy range. Fully quantum mechanical scattering calculations of Althorpe are presented. These results agree well with the measured differential cross section at all collision energies except 1.54 eV. This discrepancy is not well understood, although the calculated DCS changes wildly with energy near this energy, and it is suspected that these changes are related to the disagreement. Overall good agreement between theory and experiment helps construct an interpretation for the observed scattering. Calculations indicate the presence of two mechanisms; a direct mechanism resulting mostly in backward scattered products, and an indirect mechanism that appears about 15 fs later. Interference between the two mechanisms causes the observed changes in the DCS, including the forward scattering. Comparison between theory and experiment for the integral cross section is quantitative. The mechanism that causes changes is the DCS does not manifest itself as changes in the integral cross section.

Pedogenesis in rain gardens: The role of earthworms and other organisms in long-term soil development

Ayers, Emily Mitchell University of Maryland, College Park 2009 해외공개박사

As bioretention comes into widespread use, it has become increasingly important to understand the development of bioretention soils over time. The objective of this research is to investigate the development of bioretention soils and the importance of ecological processes in the performance of rain gardens. The research includes descriptive studies of pre-existing rain garden soil profiles, laboratory experiments quantifying the effect of earthworms on infiltration rates, and a simulation model describing the influence of earthworms and soil organic matter on infiltration. Surveys of several different rain gardens of various ages provide the first detailed descriptions of rain garden soil profiles. The study revealed a great deal of biological activity in rain gardens, and evidence of pedogenesis even in very young sites. The uppermost soil layers were found to be enriched with organic matter, plant roots, and soil organisms. The field sites surveyed showed no signs of clogging due to the trapping of suspended solids carried in stormwater runoff. Some evidence was found of higher than expected infiltration rates at the field sites, which may be attributable to the effects of bioturbation by living organisms. The ability of earthworms to mitigate the effects of trapped suspended solids on bioretention soils was assessed in the laboratory. Results show that earthworms are capable of maintaining the infiltration rate of bioretention soils, but that their effects have a high degree of variability. This variability is attributed to soil aggregate instability caused by the oversimplification of the ecosystem. Other organisms play a significant role in stabilizing earthworm burrows and casts, and may be essential ingredients in a self-maintaining bioretention ecosystem. A simulation model of the action of earthworms on soil infiltration rates was developed in order to illustrate the physical processes taking place as a result of earthworm activity. The model was calibrated using data from the field study and microcosm experiment. This research is intended to provide a first glimpse into the biological processes at work in rain garden soils. The research shows that soil organisms are present in rain gardens, and suggests that their impact on bioretention performance may be significant.

Debt and dependency: Does conditionality really harm health standards in developing countries?

Ayers, Michael R State University of New York at Albany 2005 해외박사(DDOD)

In recent years, growing debt in developing countries has become a major concern to sociologists and other students of global inequality. Countries experiencing substantial debt problems often participate in multilateral conditionality agreements brokered by the IMF and the World Bank. An emergent theoretical approach, built upon dependency theory, argues that these conditionality agreements are detrimental to living conditions in developing nations (Bradshaw et al., 1993). Specifically, the agreements are thought to impose national policies built on a liberal model which, proponents argue, leaves the majority of the population with reduced access to health care and education, while serving the needs of the wealthy and transnational corporations, including foreign investors. The current study tests the dependency-based assertion that conditionality agreements are detrimental to changes in health standards, as well as the liberal argument to the contrary. I propose a new model, the distributive environment model, which suggests that the impact of conditionality agreements on health standards in developing countries is best understood in the context of the effect of the socio-cultural environment on the distribution of the benefits of economic growth in society. Analysis indicates that conditionality does not affect health standards in developing countries. Statistical interactions were found between the effects of educational enrollment and ethnic fragmentation and the effect of economic growth on health standards. It is concluded that in the absence of economic growth, health standards can be improved in an inclusive socio-political environment.