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- Creators: Arizona State University
- Status: Published
Description
Maximal oxygen uptake (VO2max) declines with age and is a predictor of morbidity and mortality risks. Due to these implications, accurate assessment and determination of VO2max are important for the older population. Without the presence of a VO2 plateau, secondary criteria are used to determine whether the test resulted in a maximal value. However, inconsistent secondary criteria do not account for intersubject variability. To circumvent this issue, a verification phase following a traditional ramp assessment may be utilized. The purpose of this study was to compare verification phase strategies in older adults. A secondary purpose of this study was to examine the repeatability of the ramp assessment performed during each visit. Twenty-two older adults between 60 and 80 years of age were recruited to participate in the study. Each subject completed two experimental trials in a randomized, counterbalanced cross-over design. Both trials consisted of a ramp test and verification phase at either 85% (VP85) or 110% (VP110) of the peak work rate achieved during the ramp (Ramp85 and Ramp110, respectively). Expired gases and heart rate (HR) were monitored continuously and measured every ten seconds. VO2peak was determined by the highest 30-second averages for the ramp and verification phases. No significant differences were observed for absolute (L/min) VO2peak between VP85 (P = 0.679) or VP110 (P = 0.200) and the associated ramp. There was also no significant difference in maximal HR between VP85 (P = 0.243) or VP110 (P = 0.085) and the associated ramp. However, individual data shows that 36% of individuals achieved a 2% greater VO2 (L/min) during the VP85 compared to the Ramp85, while only 15% of subjects achieved a 2% greater VO2 (L/min) during the VP110 compared to Ramp110. No significant differences (P < 0.05) were found for most variables between Ramp1 and Ramp2. These data suggest that if a verification phase is employed for VO2max assessment in otherwise healthy older adults, a power slightly below peak work rate may provide a more accurate assessment compared to a power slightly above peak work rate.
ContributorsVillanueva, Ian Robert (Author) / Dickinson, Jared M (Thesis advisor) / Gaesser, Glenn A (Committee member) / Angadi, Siddhartha S (Committee member) / Arizona State University (Publisher)
Created2019
Description
I examined how competition affects the way animals use thermal resources to control their body temperature. Currently, biologists use a cost benefit analysis to predict how animals should regulate their body temperature. This current theory of thermoregulation does not adequately predict how animals thermoregulate in the wild. While the model works well for animals in low cost habitats, it does not work as well for animals in high cost habitats. For example, animals that are in habitats of low thermal quality thermoregulate more precisely than predicted by the current model. One reason these predictions may be wrong is that they do not account for interactions between animals. By including these interactions in future predictions, a more accurate model of thermoregulatory behavior can be created.
Before developing a theory for all animals, a model needs to be developed for a single model animal, such as fruit flies, that can be used to empirically examine how organisms thermoregulate under competition. My work examines how flies behave around other flies and develops a game theory model predicting how they should optimally behave. More specifically, my research accounts for competition among larvae by using game theory to predict how mothers should select sites when laying eggs. Although flies prefer to lay their eggs in places that will offer suitable temperatures for the development of their larvae, these sites become less suitable when crowded. Therefore, at some density of eggs, cooler sites should become equally beneficial to larvae when considering both temperature and competition. Given this tradeoff, an evolutionarily stable strategy (ESS) emerges where some flies should lay eggs in cooler sites while other flies should lay eggs at the warmer temperature. By looking at the fitness of genotypes in habitats of differing quality (competition, temperature, food quality, space), I modeled the ESS for flies laying eggs in a heterogeneous environment. I then tested these predictions by observing how flies compete for patches with different temperatures.
Before developing a theory for all animals, a model needs to be developed for a single model animal, such as fruit flies, that can be used to empirically examine how organisms thermoregulate under competition. My work examines how flies behave around other flies and develops a game theory model predicting how they should optimally behave. More specifically, my research accounts for competition among larvae by using game theory to predict how mothers should select sites when laying eggs. Although flies prefer to lay their eggs in places that will offer suitable temperatures for the development of their larvae, these sites become less suitable when crowded. Therefore, at some density of eggs, cooler sites should become equally beneficial to larvae when considering both temperature and competition. Given this tradeoff, an evolutionarily stable strategy (ESS) emerges where some flies should lay eggs in cooler sites while other flies should lay eggs at the warmer temperature. By looking at the fitness of genotypes in habitats of differing quality (competition, temperature, food quality, space), I modeled the ESS for flies laying eggs in a heterogeneous environment. I then tested these predictions by observing how flies compete for patches with different temperatures.
ContributorsBorchert, Jason (Author) / Angilletta Jr., Michael (Thesis advisor) / Pratt, Stephen (Committee member) / Harrison, Jon (Committee member) / DeNardo, Dale (Committee member) / Mitchell, William (Committee member) / Arizona State University (Publisher)
Created2018
Description
As white-nose syndrome (WNS) spreads across North America, generating baseline data on bats hibernating outside of the affected area is critical. To illustrate, despite the imminent arrival of Pseudogymnoascus destructans (Pd) to Arizona (AZ), little is known about bat hibernation in the Southwest. With the current amount of information, if Pd spreads throughout the state, detection of cases would be limited, and severity of disease and magnitude of mortality impossible to accurately estimate. Thus, my study monitored hibernating bats in AZ to increase knowledge and investigate potential WNS impacts on these populations. Utilizing passive acoustic monitoring, internal cave surveys, environmental monitoring, and thermal imaging, my study quantified microclimate preferences, hibernation lengths, hibernation behaviors, population dynamics, and species compositions of bats hibernating in three north-central AZ caves. Hibernation lasted between 104 and 162 days, from late October through mid- March, during which time bats (primarily Corynorhinus townsendii and Myotis species) roosted at locations with an average of 4.7oC (range = -0.2oC – 12.1oC), 59.6% relative humidity (range = 39.6% - 75.9%), and 0.4 kPa water vapor pressure deficit (range = 0.2 kPa – 0.8 kPa). A maximum of 40 individuals were observed in any hibernacula and clustering behavior occurred in only 4.1% of torpid bats. Bats selected cold and dry roost sites within caves. Results suggest Pd could proliferate on some bats hibernating in colder areas of AZ hibernacula, yet the range of observed roost humidities was lower than optimal for Pd growth. Hibernation length in north-central AZ is longer than predicted for Myotis species at similar latitudes and may be long enough to pose over- winter survival risks if WNS emerges in AZ populations. Yet, a natural tendency for mid-winter activity, which I observed by multiple species, may allow for foraging opportunities and water replenishment, and therefore promote survival in bats utilizing these arid and cold habitats in winter. Additionally, the relatively solitary behaviors I observed, including virtually no clustering activity and a maximum of 40 bats per hibernacula, may keep rates of Pd transmission low in these Southwest bat populations.
ContributorsHutcherson, Hayden K (Author) / Bateman, Heather (Thesis advisor) / Moore, Marianne (Committee member) / Lewis, Jesse (Committee member) / Arizona State University (Publisher)
Created2023
Description
PURPOSE: The aim of this study was to determine if the linear and nonlinear components of the energy expenditure-walking speed relationship are influenced by body mass index (BMI; kg/m2). The secondary aims were to determine if the relationship was influenced by age, height, and sex. METHODS: Subjects (n=182) walked at 2, 3, and 4 mph for six minutes each with oxygen consumption (V̇O2; ml/kg/min) and measured via indirect calorimetry and converted to energy expenditure (EE; W/kg). Because of the curvilinear change in metabolic rate with increase in walking speed, polynomial random coefficient regression (PRCR) was employed to produce a model which captures the slope of change. Individual level linear and quadratic coefficients were analyzed for relationships with BMI, age, height, and sex. RESULTS: The net V̇O2 regression formula for walking was 1.79(x-3)2+4.97(x-3)+9.32 where x is speed in mph. BMI was modestly correlated with the quadratic coefficients (r = 0.15 to 0.17, p = 0.02 to 0.04) but not the linear coefficients (r =0.02- 0.07, p = 0.36-0.78) for V̇O2 and EE. There was no difference in coefficients between normal BMI (18.5-<25.0 kg/m2), overweight (25-<30.0 kg/m2) and obese (>30.0 kg/m2) groups (H = 1.5-4.0, p = 0.13-0.48). Delta V̇O2 for 2-3 mph, 3-4 mph, and 2-4 mph were not correlated with BMI (r = -0.02 - 0.13, p = 0.11 - 0.41). Height was inversely correlated with the linear and quadratic coefficients (r = -0.32 to -0.14, p = 0.09). Age was not correlated to coefficients (r = -0.16 to 0.32, p = 0.06-0.44). The coefficients for sex were not different after controlling for height in ANCOVA (F(1,179)=0.3-2.9, p >0.09). Age was not correlated to coefficients (r = -0.16 to –0.32, p = 0.06-0.44). CONCLUSION: Although BMI had a modest relationship with the quadratic coefficient, it explained less than 3% of the variance in V̇O2 or EE. Combined with the absence of a delta V̇O2 or a linear component, BMI does not influence the energy expenditure-walking speed relationship. Height explained up to 9% of the variance in the coefficients and eliminated apparent sex differences. Age was not related to the coefficients.
ContributorsBeaumont, Joshua S (Author) / Gaesser, Glenn A (Thesis advisor) / Angadi, Siddhartha S (Thesis advisor) / Adams, Marc A (Committee member) / Dickinson, Jared M (Committee member) / Peterson, Daniel S (Committee member) / Arizona State University (Publisher)
Created2023
Description
The global spread of the Aedes aegypti mosquito, a competent disease vector, is occurring at an alarming pace. These invasive mosquitos have spread to latitudes once thought inaccessible due to thermal and hydric limitations, including Maricopa County, AZ, where strong increases in population size has occurred over the last decade. The Aedes aegypti in Maricopa County follow a highly seasonal pattern with populations all but disappearing each winter, only to return and build exponentially though the summer and fall. Maricopa County’s winters are relatively mild, which raises the question of whether further global climate change will warm conditions enough to create a broadened seasonal breeding period, or worse yet, year-round mosquito activity within desert southwest cities. This dissertation focuses on exploring the possible seasonal constraints on the egg, larva, and adult life stages of the Aedes aegypti mosquito within a suburban desert ecosystem. I explored whether climatic warming would raise temperatures enough to enable survival and development of these animals during the winter offseason. I determined that larval growth and adult flight are constrained by ambient winter temperatures in Maricopa County, explaining the currently observed winter crash in populations. However, warming by only a few degrees Centigrade could enable successful larval growth and development, as well as adult flight, even during the coldest desert months. I found that load and temperature interact to determine the flight cost of mosquitos, which can very up to six-fold, with higher temperatures likely increasing their flight performance but decreasing their distance capacities and increasing their need for fuel.
Aedes aegypti likely primarily overwinters as eggs. However, I showed that the vast majority of Aedes aegypti eggs die overwinter in Maricopa County. By manipulating humidity in eggs exposed to ambient air temperatures, I showed that desiccation, not cold temperatures, is the limiting factor in long-term survival of Aedes aegypti eggs. Together, my data suggests that humid, urban microhabitats may be essential for enabling overwinter egg survival in Maricopa County, providing a potential important pathway toward control of this disease vector.
ContributorsFox, Trevor (Author) / Harrison, Jon F (Thesis advisor) / Angilletta, Michael J (Committee member) / Benoit, Joshua B (Committee member) / Smith, Kirk (Committee member) / Arizona State University (Publisher)
Created2021
Description
The desire to start a family is something millions of people around the globe strive to achieve. However, many factors such as the societal changes in family planning due to increasing maternal age, use of birth control, and ever-changing lifestyles have increased the number of infertility cases seen in the United States each year. Infertility can manifest as a prolonged inability to conceive, or inability to carry a pregnancy full-term. Modern advancements in the field of reproductive medicine have begun to promote the use of Assisted Reproductive Technologies (ART) to circumvent reduced fertility in both men and women. Implementation of techniques such as In Vitro Fertilization, Intracytoplasmic Sperm Injection, and Pre-Implantation Genetic Testing have allowed many couples to conceive. There is continual effort being made towards developing more effective and personalized fertility treatments. This often begins in the form of animal research—a fundamental step in biomedical research. This dissertation examines infertility as a medical condition through the characterization of normal reproductive anatomy and physiology in the introductory overview of reproduction. Specific pathologies of male and female-factor infertility are described, which necessitates the use of ARTs. The various forms of ARTs currently utilized in a clinical setting are addressed including history, preparations, and protocols for each technology. To promote continual advancement of the field, both animal studies and human trials provide fundamental stepping-stones towards the execution of new techniques and protocols. Examples of research conducted for the betterment of human reproductive medicine are explored, including an animal study conducted in mice exploring the role of tyramine in ovulation. With the development and implementation of new technologies and protocols in the field, this also unearths ethical dilemmas that further complicate the addition of new technologies in the field. Combining an extensive review in assisted reproduction, research and clinical fieldwork, this study investigates the history and development of novel research conducted in reproductive medicine and explores the broader implications of new technologies in the field.
ContributorsPeck, Shelbi Marie (Author) / Baluch, Debra P (Thesis advisor) / Maienschein, Jane (Thesis advisor) / Sweazea, Karen (Committee member) / Ellison, Karin (Committee member) / Arizona State University (Publisher)
Created2021
Description
Eusocial insect colonies have often been imagined as “superorganisms” exhibiting tight homeostasis at the colony level. However, colonies lack the tight spatial and organizational integration that many multicellular, unitary organisms exhibit. Precise regulation requires rapid feedback, which is often not possible when nestmates are distributed across space, making decisions asynchronously. Thus, one should expect poorer regulation in superorganisms than unitary organisms.Here, I investigate aspects of regulation in collective foraging behaviors that involve both slow and rapid feedback processes. In Chapter 2, I examine a tightly coupled system with near-instantaneous signaling: teams of weaver ants cooperating to transport massive prey items back to their nest. I discover that over an extreme range of scenarios—even up vertical surfaces—the efficiency per transporter remains constant. My results suggest that weaver ant colonies are maximizing their total intake rate by regulating the allocation of transporters among loads. This is an exception that “proves the rule;” the ant teams are recapitulating the physical integration of unitary organisms.
Next, I focus on a process with greater informational constraints, with loose temporal and spatial integration. In Chapter 3, I measure the ability of solitarily foraging Ectatomma ruidum colonies to balance their collection of protein and carbohydrates given different nutritional environments. Previous research has found that ant species can precisely collect a near-constant ratio between these two macronutrients, but I discover these studies were using flawed statistical approaches. By developing a quantitative measure of regulatory effect size, I show that colonies of E. ruidum are relatively insensitive to small differences in food source nutritional content, contrary to previously published claims.
In Chapter 4, I design an automated, micro-RFID ant tracking system to investigate how the foraging behavior of individuals integrates into colony-level nutrient collection. I discover that spatial fidelity to food resources, not individual specialization on particular nutrient types, best predicts individual forager behavior. These findings contradict previously published experiments that did not use rigorous quantitative measures of specialization and confounded the effects of task type and resource location.
ContributorsBurchill, Andrew Taylor (Author) / Pavlic, Theodore P (Thesis advisor) / Pratt, Stephen C (Thesis advisor) / Hölldobler, Bert (Committee member) / Cease, Arianne (Committee member) / Berman, Spring (Committee member) / Arizona State University (Publisher)
Created2022
Description
Furniture is a symbol of civilizations and conveys social-cultural identity. In SaudiArabia, after the oil discovery, radical lifestyle growth and international investors have impacted local social culture and traditional identity and altered the use and form of furniture. Although Saudi Vision 2030 aims to preserve historical buildings and architectural elements, furniture must be in the scope. This study aims to explore the Hijazi conventional seating at residential spaces, the Karaweetah, as a source of inspiration for designing and preserving cultural artifacts. The study used a multi-method research design based on hermeneutics interpretation, investigating historical nostalgic-evoking seating on Saudi millennials' perceptions and purchasing decision-making. The study involved a case study of Hijazi's Karaweetah to understand its vernacular characteristics and function, followed by design ideations based on three-dimensional prototypes of nine seating designs representing different levels of heritage inspiration. Finally, a visual questionnaire tested the historical nostalgia of Saudi millennials and its effect on their purchasing preferences.
The number of participants who interact with the study is 164, who spend an average of two to five years outside of Saudi Arabia. Most respondents were female (n=131; 79.9%), while male responses were comparatively lower (n=33; 20.1%). Nostalgic elements in seating design profoundly impact Saudi millennials' purchasing decisions by 43.3%, while others (33%) preferred the modern style due to its simplicity and unique details. The outcomes preserve the essence of conventional seating design elements while also benefiting design by providing information on traditional heritage, exploring the present, and maintaining the future of seating design based on vernacular characteristics; the study contributes to the body of knowledge. The proposed framework guides furniture design practice in identifying
vernacular characteristics and preserving cultural artifacts. It also provides valuable insight into Saudi millennials' purchasing decisions and the influence of historical nostalgic-evoking seating designs.
ContributorsBamashmous, Fatmah Omar M (Author) / Bender, Diane DB (Thesis advisor) / Brooks, Kenneth KB (Committee member) / Kwan, Sau SK (Committee member) / Arizona State University (Publisher)
Created2024