Matching Items (24)
Description
Each year, the average vehicle contributes 4.6 metric tons of carbon dioxide into the atmosphere [1]. These gases contribute to around 30,000 premature deaths each year [2] and are linked to in the increase in cases of Asthma. Human health is further impacted by the increase of greenhouse gasses in the atmosphere. Rays from the sun travel to the Earth where they are absorbed. Absorbing the sun’s rays heats up the Earth which is then radiated into space. Greenhouse gasses inhibit this process much like the glass walls in a greenhouse. As a result, the temperature of the Earth steadily increases. The greenhouse effect is dangerous because it can be linked to natural disasters, rising ocean levels, and extinction of species. One of the biggest contributors to the greenhouse effect is burning fossil fuels. Powerplants, agriculture, and transportation are some of the largest contributors to the increase of atmospheric carbon dioxide. To mitigate the effects of transportation, car companies have invested into production of alternative and renewable fuels for their products. One of the sources which has gained popularity recently, is the use of electricity to power our vehicles. Tesla has spearheaded the electric car movement and is largely responsible for this beneficial shift. One issue with this approach is that a majority, around 76.3%, of Americans drive alone on their commute [13]. The market in its current state encourages inefficient transportation due to the lack of alternatives. While motorcycles may offer a more eco-friendly and economical approach to cars, many are afraid of potential hazards of using this mode of transportation. The introduction of electric bikes offers an interesting approach to improving this efficiency and safety issue. The wide availability to customers offers an alternative which pushes the traditional distance limits for commuting on a bicycle. Since the market is relatively new, several issues pose challenges to consumers. This research aims to clarify and analyze the electric bike market in order to supply a potential customer with the tools needed to acquire a high quality and reasonably price bike.
ContributorsFriedrich, Collin Anthony (Author) / Lee, Hyunglae (Thesis director) / Lacy, Gerald (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The collision of India and Eurasia constructed the Himalayan Mountains. Questions remain regarding how subsequent exhumation by climatic and tectonic processes shaped the landscape throughout the Late Cenozoic to create the complex architecture observed today. The Mount Everest region underwent tectonic denudation by extension and bestrides one of the world’s most significant rain shadows. Also, glacial and fluvial processes eroded the Everest massif over shorter timescales. In this work, I review new bedrock and detrital thermochronological and geochronological data and both one- and two-dimensional thermal-mechanical modeling that provides insights on the age range and rates of tectonic and erosional processes in this region.
A strand of the South Tibetan detachment system (STDS), a series of prominent normal-sense structures that dip to the north and strike along the Himalayan spine, is exposed in the Rongbuk valley near Everest. Using thermochronometric techniques, thermal-kinematic modeling, and published (U-Th)/Pb geochronology, I show exhumation rates were high (~3-4 mm/a) from at least 20 to 13 Ma because of slip on the STDS. Subsequently, exhumation rates dropped drastically to ≤ 0.5 mm/a and remain low today. However, thermochronometric datasets and thermal-kinematic modeling results from Nepal south of Everest reveal a sharp transition in cooling ages and exhumation rates across a major knickpoint in the river profile, corresponding to the modern-day Himalayan rainfall transition. To the north of this transition, exhumation histories are similar to those in Tibet. Conversely, < 3 km south of the transition, exhumation rates were relatively low until the Pliocene, when they increased to ~4 mm/a before slowing at ~3 Ma. Such contrasting exhumation histories over a short distance suggest that bedrock exhumation rates correlate with modern precipitation patterns in deep time, however, there are competing interpretations regarding this correlation.
My work also provides insights regarding how processes of glacial erosion act in a glacio-fluvial valley north of Everest. Integrated laser ablation U/Pb and (U-Th)/He dating of detrital zircon from fluvial and moraine sediments reveal sourcing from distinctive areas of the catchment. In general, the glacial advances eroded material from lower elevations, while the glacial outwash system carries material from higher elevations.
A strand of the South Tibetan detachment system (STDS), a series of prominent normal-sense structures that dip to the north and strike along the Himalayan spine, is exposed in the Rongbuk valley near Everest. Using thermochronometric techniques, thermal-kinematic modeling, and published (U-Th)/Pb geochronology, I show exhumation rates were high (~3-4 mm/a) from at least 20 to 13 Ma because of slip on the STDS. Subsequently, exhumation rates dropped drastically to ≤ 0.5 mm/a and remain low today. However, thermochronometric datasets and thermal-kinematic modeling results from Nepal south of Everest reveal a sharp transition in cooling ages and exhumation rates across a major knickpoint in the river profile, corresponding to the modern-day Himalayan rainfall transition. To the north of this transition, exhumation histories are similar to those in Tibet. Conversely, < 3 km south of the transition, exhumation rates were relatively low until the Pliocene, when they increased to ~4 mm/a before slowing at ~3 Ma. Such contrasting exhumation histories over a short distance suggest that bedrock exhumation rates correlate with modern precipitation patterns in deep time, however, there are competing interpretations regarding this correlation.
My work also provides insights regarding how processes of glacial erosion act in a glacio-fluvial valley north of Everest. Integrated laser ablation U/Pb and (U-Th)/He dating of detrital zircon from fluvial and moraine sediments reveal sourcing from distinctive areas of the catchment. In general, the glacial advances eroded material from lower elevations, while the glacial outwash system carries material from higher elevations.
ContributorsSchultz, Mary Hannah (Author) / Hodges, Kip V (Thesis advisor) / Whipple, Kelin X (Committee member) / Semken, Steven (Committee member) / Heimsath, Arjun M (Committee member) / Till, Christy (Committee member) / Arizona State University (Publisher)
Created2017
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
Extreme heat and its human impacts are significant public health challenges that disproportionately affect certain populations. Often, people with the least resources to cope with the heat also live in the hottest regions of cities. Previous heat vulnerability research has predominantly been conducted at a coarse geographic scale, yet translating relationships measured at aggregated scales to the individual level can result in ecological fallacy. Prior work has also primarily studied the most severe health outcomes: hospitalization/emergency care and mortality. It is likely that magnitudes more people are experiencing negative health impacts from heat that do not necessarily result in medical care. Such less severe impacts are under-researched in the literature.This dissertation addresses these knowledge gaps by identifying how social characteristics and physical measurements of heat at the individual and household level act independently and in concert to influence human heat-related outcomes, especially less severe outcomes. In the first paper, meta-analysis was used to quantify the summary effects of vulnerability indicators on incidence of heat-related illness. More proximal vulnerability indicators (e.g., residential air conditioning use, indoor heat exposure, etc.) tended to have the strongest impact on odds of experiencing heat-related illness than more distal indicators. In the next paper, indoor air temperature observations were related to the social characteristics of the residents. The strongest predictor of indoor air temperature was the residents’ ideal thermally comfortable temperature, despite affordability. In the final paper, fine scale biometeorological observations of the outdoor thermal environment near residents’ homes were linked to their experience with heat-related illness. The outdoor thermal environment appeared to have a stronger, more consistent impact on heat-related illness among households in a lower income neighborhood compared to a higher income one. These findings affirm the value of employing residential heat mitigation solutions at the individual and household scale, indoors and outdoors. Across all chapters, the indoor thermal environment, and the ability to modify it, had a clear impact on residents’ comfort and health. Solutions that target the most proximal causal factors of heat-related illness will likely have the greatest impact on reducing the burden of heat on human health and well-being.
ContributorsWright, Mary K (Author) / Hondula, David M (Thesis advisor) / Larson, Kelli L (Committee member) / Middel, Ariane (Committee member) / Arizona State University (Publisher)
Created2023