Browsing by Subject "Behavior"
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Item Alcohol and Accidents(Council for Advanced Transportation Studies, 1977-03) Young, Robert K.; Valentine, Deborah; Williams, Martha S.The relationship between drinking and driving is a complex one. In general, the probability of a crash increases as blood alcohol concentration (BAC) increases. Physiological changes with increased BAC impair attention span, alertness, visual acuity, and reaction times. Risk-taking behavior is increased with alcohol consumption. Alcohol is particularly detrimental for the inexperienced driver as well as for the driver in unfamiliar territory. This report covers research of three major types: research on the physiological effects of alcohol, laboratory and simulation studies of alcohol as it affects driver skills, and epidemiological studies of alcohol-related accidents in field settings.Item All's fly in love and war(2019-05) Park, Annie, Ph. D.; Atkinson, Nigel (Nigel S.); Wolf, Fred; Harris, Robert Adron; Phelps, Steve; Pierce, JonathanAlcoholism is a serious and widespread disorder that has a complex pathophysiology and can cause extreme changes in behavior. These changes in behavior arise from alcohol affecting the neurobiological systems in an organism. Flies share many similar alcohol related behavior with humans and they also share many of the same neurobiological systems. There are many advantages with using flies to understand alcohol related behaviors in humans (e.g. large genetic toolkit). However, flies have fewer behavioral models that assess for alcohol-related behaviors, which can limit the potential of using this model organism. Can we model more sophisticated alcohol-related behaviors in flies? In this dissertation, I provide evidence that flies share a number of alcohol-related behaviors with humans. In the first section, I develop an alcohol preference assay that demonstrates sexually dimorphic alcohol preference. In the second section, I characterize a novel low dose alcohol behavior in male flies that is male flies become more aggressive when treated with alcohol. In the third section, I focus on the female response to low dose alcohol, which is females become more receptive to courtship and less choosy about mates after an alcohol treatment. In the fourth section, I present data that demonstrates how a gene fruitless is alcohol responsive and could be contributing to some alcohol behavioral phenotypes. Taken together, this work expands the potential of flies to be used as a model organism for alcohol-related behaviors in humans.Item Astrocytes in alcohol use disorder(2020-05-08) Erickson, Emma Kerstin; Harris, R. Adron; Mayfield, R. Dayne (Roy Dayne), 1958-; Contreras, Lydia M; Eberhart, Johann K; Iyer, Vishwanath RExcessive alcohol use causes abundant molecular adaptations throughout the brain, contributing to the pathology of alcohol use disorders (AUDs). Over 50 years of alcohol research has provided insight into brain regions and neurotransmitter systems associated with the development and maintenance of addiction. However, the cellular specificity of alcohol-related functional changes and their contributions to the neurobiology of AUDs remain largely unknown. In addition to neurons, a large percentage of brain space is occupied by glial cells, including astrocytes. Until recently, astrocytes were thought to be simple, passive support cells with no significant impact on behavior. This philosophy has begun to fade with new data demonstrating astrocytes are actively involved in regulating brain function and have the potential to be critical modulators of brain disorders like addiction. In this dissertation, I investigate the role of astrocytes in alcohol-induced molecular adaptations and behaviors. In the first two sections, I present transcriptome signatures of astrocytes isolated from mice subjected to different mouse models of AUD. I identify important biological pathways affected by alcohol that could disrupt cellular function. In the next section, I reveal astrocyte involvement in alcohol consumption and intoxication. Finally, I explore how astrocyte function affects acute behavioral responses to ketamine, a drug with similar molecular pharmacology as ethanol. Altogether, this work uncovers novel roles for astrocytes in behavioral responses to drugs while offering an array of promising astrocyte-specific molecular targets for future interrogation.Item Behavioral and molecular mechanisms of pheromone transmission in the honey bee (Apis mellifera)(2017-08) Ma, Rong, Ph. D.; Mueller, Ulrich G.; Hofmann, Johann; Gilbert, Lawrence E; Jha, Shalene; Grozinger, Christina MThe European honey bee (Apis mellifera) has a sophisticated system of pheromonal signals that mediate a wide range of behaviors important for their fitness, including reproductive dominance, nest defense, and cooperative brood care. In honey bees, there are two distinct pheromones emitted by larvae, brood pheromone and (E)-beta-ocimene. By integrating behavior, chemical ecology, and transcriptomics, this dissertation analyzes several key stages in signal transmission in a systematic effort to understand how these two pheromones affect behavior, and in the process, generates a synthetic understanding of a highly complex system of communication. Previous studies have explored behavioral and gene expression patterns related to honey bee pheromones; however, none have compared the roles that two divergent pheromones from a common source play in rapid regulation of foraging behavior. Furthermore, while previous studies have investigated the mechanisms of pheromone detection and the factors involved in regulation of foraging behavior, it remains unclear how individual responses to pheromone exposure scales to colony-level changes in behavior. By investigating the behavioral, physiological, and genomic influences of honey bee chemical communication, this dissertation links phenotypic plasticity in behavior to gene expression profiles in the brain and provides insights into the evolution of a sophisticated chemical language.Item Binocular integration using stereo motion cues to drive behavior in mice(2019-05) Choi, Veronica; Priebe, Nicholas; Zemelman, Boris; Huk, Alexander C; Colgin, Laura L; Geisler III, Wilson S; Nauhaus, IanThe visual system presents an opportunity to study how two signals converge to generate a novel representation of the world: depth. The slight difference in positions between the two eyes means that different images are encoded by the left and right eyes by generating disparity signals. Another way to generate depth signals is by presenting different motion signals to the two eyes. Even though the binocular visual system has been studied for a long time, the mechanisms behind binocular integration when objects move in depth are largely unknown. In this dissertation, I demonstrate a new model for studying motion-in-depth signals using mice. Mice are an attractive animal to study the binocular visual system not only because they share common visual pathway as primates and other mammals, but also because there are genetic tools that can be used to study the underlying circuitry for binocular integration during motion-in-depth cues. Thus far there have been very few studies regarding binocularity in mice. This dissertation will focus on the behavioral output during stereoscopic motion-in-depth signals in mice and investigate visual areas involved in these behaviors. In the first section, I investigate whether mice discriminate motion-in-depth signals like primates, using disparity and motion signals presented to each eye. I find that mice are able to discriminate towards and away stimuli and that the binocular neurons in the visual cortex were critical for the computation of this signal. In the second section we measured optokinetic eye movement generated by motion-in-depth stimulus. I found that vergence eye movement in mice is driven primarily by the motion signals presented in each eye. This phenomenon can be explained largely by the summation of monocular motor signals of the two eyes that happens subcortically. These two experiments both show clear behavioral output that can be only generated when presented with binocular motion-in-depth signals. I find both cortical and subcortical components of binocular integration that are responsible for the generation of these behavior outputs which demonstrates the complicated nature of binocular integration associated with motion-in-depth signals. My work in this dissertation provides the foundation for studying binocular integration in rodentsItem Boosting Lunch Is In The Bag(2011-12) Almansour, Fawaz; Briley, Margaret E.Lunch Is In The Bag (LIITB) was a multi-level behavioral intervention with the goal of increasing the amounts of fruits, vegetables, and whole grains that parents pack in their preschoolers' lunches. The purpose of this dissertation project was to: 1) to examine the temperatures of perishable food items packed in preschoolers' sack lunches; 2) to examine parents' psychosocial constructs that relate to packing fruits, vegetables, and whole grains at four periods during the booster study; 3) to assess the servings of fruits, vegetables, and whole grains with the related nutrient content at four periods during the booster study. The four assessment periods are before LIITB, after LIITB, before the one-week booster, and after the one-week booster. Results showed that more than 97 percent of perishable food items in the sack lunches were stored at unacceptable temperatures (40-140°F). Servings of vegetables (-0.15, p=0.05) and whole grains (-0.53, p<0.0001) in preschool lunches decreased significantly before the booster in the intervention group. The booster increased the servings of vegetables (0.10, p=0.09) and whole grains (0.16, p =0.01) compared to booster baseline. The one-week booster increased thiamin, dietary fiber, and vitamin C content of foods in preschoolers' lunches. During the booster study, parents experienced improvement in psychosocial variables after LIITB and before the booster. Knowledge decreased before the booster. Parents' psychosocial variables were linked to packing more vegetables and significantly more whole grains due to the intervention. Education for parents and the public must focus on methods of packing safe, healthy lunches in order to prevent foodborne illness and chronic disease. The results of this study provide data for continued examination of an area of parental behavior related to packing lunches for their children. The booster study demonstrated that a booster was important for maintenance of program outcomes, and to increase the servings of vegetables and whole grains that parents packed in their preschool children's lunches.Item Can We Dissociate Contingency Learning from Social Learning in Word Acquisition by 24-Month-Olds?(Public Library of Science, 2012-11-21) Bannard, Colin; Tomasello, MichaelWe compared 24-month-old children’s learning when their exposure to words came either in an interactive (coupled) context or in a nonsocial (decoupled) context. We measured the children’s learning with two different methods: one in which they were asked to point to the referent for the experimenter, and the other a preferential looking task in which they were encouraged to look to the referent. In the pointing test, children chose the correct referents for words encountered in the coupled condition but not in the decoupled condition. In the looking time test, however, they looked to the targets regardless of condition. We explore the explanations for this and propose that the different response measures are reflecting two different kinds of learning.Item Characterization of MTHFD2L expression and alternative splicing and loss of MTHFD1L activity in murine embryos and adults(2017-05) Bryant, Joshua Dale; Appling, Dean Ramsay; Drew, Michael; Finnell, Richard; Hoffman, David; Mills, Edward; Tiziani, StefanoIn Eukaryotes, folate-dependent one-carbon (1C) metabolism is a highly compartmentalized process in which mitochondria play a central role. Defects in folate metabolism are associated with diseases such as cancer, Alzheimer's disease, and neural tube defects (NTDs). 1C units are attached to tetrahydrofolate (THF) and carried in various oxidation states between folate-dependent enzymes. There is an exchange of 1C units across the mitochondrial membrane, with 1C donors such as serine and glycine being oxidized to formate in the mitochondria, which is then released into the cytoplasm. 1C units in the cytoplasm can be used for the synthesis of purines, thymidylate, and methionine for the methyl cycle. The core of the pathway in both compartments is catalyzed by the methylene-tetrahydrofolate (MTHFD) gene family. These enzymes catalyze the reversible interconversion between CH₂-THF, CH⁺-THF, CHO-THF, and formate. The cytoplasmic protein MTHFD1 is trifunctional and carries the CH₂-THF dehydrogenase, CH⁺-THF cyclohydrolase, and 10-CHO-THF synthetase activities necessary to carry out these interconversions. In the mitochondria, two bifunctional isozymes, MTHFD2 and MTHFD2L, carry the dehydrogenase/cyclohydrolase (D/C) activities. The monofunctional enzyme MTHFD1L is responsible for the synthetase activity. MTHFD2 is only expressed in embryos and transformed cells, and the enzyme responsible for the D/C activity in adults was unknown until the recent discovery of MTHFD2L. In this work, characterization of the expression of MTHFD2L in mouse embryos and adults is described. Expression of MTHFD2L in embryos was found to be switched on between embryonic days 8.5-10.5, and remains high throughout development. MTHFD2L is also widely expressed in adults, with highest expression in brain and lung. A splice variant of MTHFD2L lacking exon 8 was found to be abundant in embryos but was not catalytically active in vitro or in vivo. MTHFD1L is an essential protein, and SNPs in MTHFD1L are associated with increased risk for Alzheimer's disease and NTDs in humans. Loss of MTHFD1L activity in adult mice with and without a folate deficient diet was investigated. Indications of sex-dependent behavioral anomalies were found, with evidence for genotype-dependent hyperactivity in male mice and diet-dependent anxiety in female mice, but further investigation of these findings is warranted. Finally, metabolic defects associated with NTDs and growth restriction in MTHFD1L-null (Mthfd1l [superscript z/z]) embryos were identified. Glycolysis, the TCA cycle, and the metabolism of methionine, purines, and multiple amino acids were found to be disrupted in Mthfd1l [superscript z/z] embryos. These altered metabolic pathways suggest potential future therapies for preventing NTDs in humans.Item Coping with weight-related discrepancy and potential impacts on future self-regulation of weight loss behavior : development of the WEIGHT-COPE(2011-12) Faries, Mark Daniel; Bartholomew, John B.; Kohl, Harold W.; Loukas, Alexandra; Pasch, Keryn; Tyler, DianeThe purpose of this dissertation was to develop a reliable and valid measure to assess coping responses to weight-related discrepancy in women. The decision to create such a measure stemmed from the difficulties individuals have with initiation and consistent regulation of weight-related behavior. When salient, perceived discrepancies with one’s weight or body can be emotionally laden, producing negative affective responses and discontent, labeled here as dissatisfaction. The individual must then find ways to cope. However, not all coping responses are equal, and are theorized to have varied impacts on future regulation of weight loss efforts. The present research addressed these issues by developing a theoretically-based measure, labeled the WEIGHT-COPE. The WEIGHT-COPE originally sought to capture healthy and unhealthy problem-focused coping efforts to lose weight, as well as approach and avoidance coping efforts theorized as more distal influences on problem-focused efforts. The WEIGHT-COPE and other relevant measures were completed by 470 females ages 18-35 years. Results of an exploratory factor analysis revealed a 38-item measure consisting of eight coping factors: Exercise/Physical Activity, Healthy Eating, Cutting Calories/Appetite Suppression, Supplement Use, Monitor/Planning, Disengage/Denial, Camouflage, and Acceptance/Positive Reframing. All factors were internally consistent ( = 0.71 to 0.89), and converged with other pertinent measures of weight satisfaction, weight controllability/changeability, social physique anxiety, self-esteem, weight loss efficacy, physical activity level, dietary intake and objectified body consciousness. To test theoretical implications on future self-regulation of weight loss behavior, a structural regression model was run utilizing the WEIGHT-COPE factors. The factors were associated in a theoretically-driven pattern, illustrating that coping responses to weight-related discrepancy have varied impact on weight loss behavior choice. Thus, the present findings provide preliminary support for the WEIGHT-COPE and suggest that individuals cope with weight-related discrepancy in different ways, which may then have various impacts future self-regulation of weight loss behavior.Item Development of a questionnaire to comprehensively quantify behavior and temperament traits in dogs relinquished to an animal shelter(2007-12) Mollaghan, Diane M.; Gosling, SamBehavior problems are some of the leading reasons for relinquishment of pets to animal shelters. The result of all these unwanted pets is the destruction of millions of pets in animal shelters each year. Despite the prevalence and importance of behavior problems in dogs, only a dearth of literature focuses on this issue. The central goal of this paper is to introduce an instrument that is designed to comprehensively and effectively quantify dog behavior and temperament. Six instruments used in previous research will be introduced and evaluated against six criteria, and will be utilized in the development of a new instrument. This new instrument will improve animal welfare by providing a multi-purpose tool necessary for researchers to examine pet problem behavior across a variety applied animal contexts: Animal sheltering, service-dog selection and clinical behavioral medicine. A snapshot of data from 291 completed Pet Owner Relinquishment questionnaires will demonstrate the usefulness of this newly constructed instrument.Item Developmental timing, type, severity, and chronicity of early adverse childhood experiences : associations with adolescent mental health and behaviors(2022-11-03) Berendzen, Hannah Michelle; Gershoff, Elizabeth T.Despite the abundant literature demonstrating the negative consequences of adverse childhood experiences (ACEs) across the lifespan, there is little known about the specific nuances in how children experience adversity. Using longitudinal data from the Fragile Families and Child Wellbeing Study, this thesis examined associations between adolescent wellbeing and the various ways in which they experienced ACEs earlier in life. Results indicated that ACEs are related to poor adolescent mental health and negative behaviors. ACEs at age nine had particularly strong associations with negative adolescent outcomes over and above ACEs that occurred at earlier ages. In addition, the impacts of individual ACEs varied according to how they were experienced earlier in life, including the single occurrence, severity, and chronicity of each type of adversity. These results suggest that the developmental timing, type, severity, and chronicity of ACEs are important considerations for both future research and intervention efforts.Item Diazepam binding inhibitor and tolerance to ethanol in Drosophila melanogaster(2012-12) Robles, Roseanna Beth; Atkinson, Nigel (Nigel S.); Aldrich, Richard; Duvauchelle, Christine; Mihic, John; Zakon, HaroldTolerance to ethanol is an endophenotype of alcoholism, allowing the study of a complex psychiatric condition using animal models. To identify new genes involved in the acquisition of tolerance, I designed an automated and high-throughput tolerance assay and screened a collection of deficiency mutants for the inability to develop tolerance. The screen yielded several “regions of interest” where more than one overlapping deficiency failed to develop tolerance. One of these regions comprised nine genes, and testing the expression levels of each gene revealed that diazepam binding inhibitor (Dbi) showed grossly increased expression in the deficiency mutant compared to wild type. Another mutant stock, with a P-element transposon inserted downstream of the Dbi gene, both failed to develop tolerance and showed further increased expression of Dbi. There are two insulator binding sites flanking Dbi, and the P-element transposon also contains insulator binding sites. Based on these results, it was hypothesized that an insulator complex kept Dbi expression low in wild type flies and that disrupting the insulator complex allowed aberrantly high expression of Dbi in the mutants. Furthermore, we assumed that induction of Dbi blocked tolerance by making the mutants resistant prior to the first sedation. A UAS-DBI transgene was constructed to over-express Dbi. Induction of the UAS-DBI with a heat shock gal4 driver induced resistance to ethanol sedation; a similar response was observed in the parental control, but the effect was smaller. Although driving UAS-DBI with the neural elav-gal4 driver did not block tolerance, the experimental stock was resistant to ethanol sedation compared to the parental controls, indicating that increased Dbi expression produced “pre-tolerance.” To confirm the theory that insulator disruption was responsible for the increase in Dbi and the resulting no-tolerance phenotype, the P-element in the second mutant was mobilized by introducing a transposase source. These offspring lines were analyzed using qualitative PCR to determine whether the transposon excised precisely, left a portion of the transposon behind, or removed some of the flanking region. A precise excision mutant was identified, but this mutation did not rescue tolerance as predicted. This result might indicate that genetic background was the cause of the no-tolerance phenotype, or it might indicate that the excision was not exactly precise and removed the native insulator binding site, causing the insulator complex to remain disrupted.Item Do Humans Optimally Exploit Redundancy to Control Step Variability in Walking?(Public Library of Science, 2010-07-15) Dingwell, Jonathan B.; John, Joby; Cusumano, Joseph P.It is widely accepted that humans and animals minimize energetic cost while walking. While such principles predict average behavior, they do not explain the variability observed in walking. For robust performance, walking movements must adapt at each step, not just on average. Here, we propose an analytical framework that reconciles issues of optimality, redundancy, and stochasticity. For human treadmill walking, we defined a goal function to formulate a precise mathematical definition of one possible control strategy: maintain constant speed at each stride. We recorded stride times and stride lengths from healthy subjects walking at five speeds. The specified goal function yielded a decomposition of stride-to-stride variations into new gait variables explicitly related to achieving the hypothesized strategy. Subjects exhibited greatly decreased variability for goal-relevant gait fluctuations directly related to achieving this strategy, but far greater variability for goal-irrelevant fluctuations. More importantly, humans immediately corrected goal-relevant deviations at each successive stride, while allowing goal-irrelevant deviations to persist across multiple strides. To demonstrate that this was not the only strategy people could have used to successfully accomplish the task, we created three surrogate data sets. Each tested a specific alternative hypothesis that subjects used a different strategy that made no reference to the hypothesized goal function. Humans did not adopt any of these viable alternative strategies. Finally, we developed a sequence of stochastic control models of stride-to-stride variability for walking, based on the Minimum Intervention Principle. We demonstrate that healthy humans are not precisely “optimal,” but instead consistently slightly over-correct small deviations in walking speed at each stride. Our results reveal a new governing principle for regulating stride-to-stride fluctuations in human walking that acts independently of, but in parallel with, minimizing energetic cost. Thus, humans exploit task redundancies to achieve robust control while minimizing effort and allowing potentially beneficial motor variability.Item Drugs and Their Effect on Driving Performance(Council for Advanced Transportation Studies, 1977-05) Valentine, Deborah; Williams, Martha S.; Young, Robert K.This report reviews the literature on the association of drug use and accidents. Research indicates widespread use of psychotropic drugs with tentative evidence to indicate their use may impair driving performance. The effects of marijuana and other hallucinogens on traffic safety and driving performance is also reviewed. The unpredictable effects of these drugs, plus their effects in combination with alcohol, indicate a need for further investigations in this area.Item The Durability of Public Goods Changes the Dynamics and Nature of Social Dilemmas(Public Library of Science, 2007-07-04) Brown, Sam P.; Taddei, FrançoisAn implicit assumption underpins basic models of the evolution of cooperation, mutualism and altruism: The benefits (or pay-offs) of cooperation and defection are defined by the current frequency or distribution of cooperators. In social dilemmas involving durable public goods (group resources that can persist in the environment–ubiquitous from microbes to humans) this assumption is violated. Here, we examine the consequences of relaxing this assumption, allowing pay-offs to depend on both current and past numbers of cooperators. We explicitly trace the dynamic of a public good created by cooperators, and define pay-offs in terms of the current public good. By raising the importance of cooperative history in determining the current fate of cooperators, durable public goods cause novel dynamics (e.g., transient increases in cooperation in Prisoner's Dilemmas, oscillations in Snowdrift Games, or shifts in invasion thresholds in Stag-hunt Games), while changes in durability can transform one game into another, by moving invasion thresholds for cooperation or conditions for coexistence with defectors. This enlarged view challenges our understanding of social cheats. For instance, groups of cooperators can do worse than groups of defectors, if they inherit fewer public goods, while a rise in defectors no longer entails a loss of social benefits, at least not in the present moment (as highlighted by concerns over environmental lags). Wherever durable public goods have yet to reach a steady state (for instance due to external perturbations), the history of cooperation will define the ongoing dynamics of cooperators.Item The ecology of blue crab (Callinectes sapidus) megalopae in the Mission-Aransas Estuary, Texas : salinity, settlement, and transport(2013-12) Bittler, Kimberly Marie; Buskey, Edward Joseph, 1952-Blue crabs are a widely distributed estuarine species with broad economic and ecological importance. Several studies have linked blue crabs to freshwater inflows, but the precise nature of this link is still uncertain, as blue crabs have a complex life cycle that utilizes both marine and estuarine environments. One potential link between blue crabs and freshwater inflows is during recruitment, when megalopae developing offshore return to estuaries before molting into juvenile crabs. Megalopae swim during the flood tide to ensure delivery into and farther up estuaries. The behaviors regulating selective tidal stream transport (STST) on the flood tide were originally studied in North Carolina in an estuary with regular freshwater inflows and a strong salinity gradient. The model of STST was re-examined in the Mission-Aransas, an estuary with episodic freshwater inflows and salinity gradients ranging from normal estuarine conditions to hypersaline during droughts. The behavioral responses of megalopae to a range of rates of salinity increase were tested, and then modeled onto rates of salinity change observed in the field to determine the theoretical ecological consequences of STST for blue crab populations in the Mission-Aransas Estuary. To validate the ecological trends predicted by the behavioral model of STST, a simple, long-term data set reflecting changes in megalopae abundance is needed. Hog’s hair collectors are a simple and widely used method of quantifying abundance of brachyuran megalopae, including blue crabs. However, the efficiency of hog’s hair collectors in sampling for megalopae is unknown. Several studies have reported poor correlations between settlement on hog’s hair collectors, transport, and abundance of megalopae in the plankton due to disparate temporal scales and potentially turbulence-driven decoupling. Each of these issues were addressed in field and flume experiments, which were used to develop a model for interpreting settlement on hog’s hair collectors in terms of transport and planktonic abundance.Item Endocrine disruptors and hormonally-sensitive windows across the life cycle of females(2023-04-21) Kunkel, Marcela Nicole; Gore, Andrea C., 1964-; Dominguez, Juan; Cormack, Lawrence; Guarraci, Fay AEndocrine-disrupting chemicals (EDCs) pose serious threats to women’s health. Deleterious effects of EDC exposure early development, particularly during hormonally-sensitive windows, are well documented in longitudinal studies, demonstrating that effects are often “hidden” until adulthood. However, exposures rarely occur once, and EDCs are not the only neuroendocrine challenge one faces over the life course. Interactions between EDC exposures and other stressors are less understood. The first two experimental chapters of this dissertation focused on perinatal exposure to Aroclor 1221 (A1221), a weakly estrogenic mixture well-established endocrine disruptors called polychlorinated biphenyls (PCBs), and peripubertal sociosexual stress using the sexual conspecific aggressive response (SCAR) model using a 2x2 design. These stressors were hypothesized to interact: SCAR was expected to exacerbate or “unmask” A1221 exposure effects in adult female rats. Experiments did not show any interactions between A1221 and SCAR, treatments exerted independent effects. In the first study, neither treatment appeared to elicit depressive-like behavioral phenotypes, but rats exposed to A1221 exhibited dexamethasone (dex) nonsuppression during a dexamethasone suppression test (DST). In the second study, SCAR exerted anxiolytic effects during open field testing. In this study, SCAR experience was paired with an odor cue, and when experimental animals were assessed for odor preference, rats that underwent SCAR tended to show a stronger preference for the odor cue. At euthanasia (~P85), there were no group differences in cytochrome c oxidase (COX) in the paraventricular nucleus (PVN) of the hypothalamus, basolateral amygdala (BLA), or ventrolateral area of the ventromedial nucleus of the hypothalamus (VMNvl), and A1221-exposed animals tended to have lower circulating corticosterone (CORT). Results suggested that, in female rats, SCAR does not elicit a stressed phenotype, perinatal A1221 exposure perturbs stress reactivity, and treatments are not associated with changes in metabolism in brain. The fourth chapter of this dissertation is a systematic literature review and meta-analysis that investigated whether EDC exposure predisposes pregnant women to peripartum depression (PPD). Pregnancy is another hormonally-sensitive window that is under researched. Results demonstrated that EDC exposures increase the odds of pregnant women developing PPD, and this is an understudied and emerging research question.Item Erratic Flu Vaccination Emerges from Short-Sighted Behavior in Contact Networks(Public Library of Science, 2011-01-27) Cornforth, Daniel M.; Reluga, Timothy C.; Shim, Eunha; Bauch, Chris T.; Galvani, Alison P.; Meyers, Lauren AncelThe effectiveness of seasonal influenza vaccination programs depends on individual-level compliance. Perceptions about risks associated with infection and vaccination can strongly influence vaccination decisions and thus the ultimate course of an epidemic. Here we investigate the interplay between contact patterns, influenza-related behavior, and disease dynamics by incorporating game theory into network models. When individuals make decisions based on past epidemics, we find that individuals with many contacts vaccinate, whereas individuals with few contacts do not. However, the threshold number of contacts above which to vaccinate is highly dependent on the overall network structure of the population and has the potential to oscillate more wildly than has been observed empirically. When we increase the number of prior seasons that individuals recall when making vaccination decisions, behavior and thus disease dynamics become less variable. For some networks, we also find that higher flu transmission rates may, counterintuitively, lead to lower (vaccine-mediated) disease prevalence. Our work demonstrates that rich and complex dynamics can result from the interaction between infectious diseases, human contact patterns, and behavior.Item An evaluation of resurgence of appropriate communicative responses in children with developmental disabilities(2011-08) Hoffman, Katherine J.; Falcomata, Terry S.; Ringdahl, JoelThe purpose of the current study was to evaluate the conditions under which resurgence of appropriate communicative responses (mands) would occur with children with developmental disabilities. The experimental preparation consisted of a sequence of conditions that included (a) the reinforcement of one mand (i.e., microswitch activation or card exchange) on a FR 1 schedule, (b) an extinction condition in which the mand was no longer reinforced, (c) the reinforcement of a second mand (i.e., microswitch activation or card exchange) on a FR 1 schedule, and (d) a test for resurgence of the first mand which consisted of placing the second mand on extinction. The results demonstrated resurgence of mands during 2 out of 3 tests for resurgence for one participant. Resurgence of mands was demonstrated during all three tests for resurgence with the second participant.Item Fatigue behavior of post-installed shear connectors used to strengthen continuous non-composite steel bridge girders(2016-08) Ghiami Azad, Amir Reza; Engelhardt, Michael D.; Williamson, Eric B., 1968-; Helwig, Todd A; Jirsa, James O; Taleff, Eric MMany older bridges in Texas are constructed with floor systems consisting of a concrete slab over steel girders. A potentially economical means of strengthening these floor systems is to connect the existing concrete slab and steel girders using post-installed shear connectors to change the behavior of the beam from non-composite to partially-composite. Since fatigue is one of the main concerns in designing bridges, investigating the fatigue properties of these post-installed shear connectors becomes crucial. Results from direct-shear testing show that post-installed shear connectors have a better fatigue life compared to conventional welded shear studs. However, based on currently available data from direct-shear tests, fatigue life of post-installed shear connectors is still inadequate for economical retrofit in some cases. Furthermore, it is unclear if direct-shear tests provide an appropriate means of evaluating fatigue performance. The objective of this dissertation is to develop new and more accurate approaches for evaluating the fatigue characteristics of post-installed shear connectors. This objective is addressed through large-scale beam fatigue tests and computational studies. The focus of the work is on evaluating fatigue life of shear connectors based on both slip and stress demands.
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