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Description
Over the past two decades there has been much discussion surrounding the potential of zoos as conservation institutions. Although zoos have clearly intensified their rhetorical and programmatic commitment to conservation (both ex situ and in situ), many critics remain skeptical of these efforts. This study was comprised of two parts: 1) an investigation of the general relationship between U.S. zoological institutions and the conservation agenda, and 2) a more specific single case study of conservation engagement and institutional identity at the Phoenix Zoo. Methods included extensive literature review, expert interviews with scholars and zoo professionals, site visits to the Phoenix Zoo and archival research. I found that the Phoenix Zoo is in the process of consciously creating a conservation-centered institutional identity by implementing and publicizing various conservation initiatives. Despite criticism of the embrace of conservation by zoos today, these institutions will be increasingly important agents of biodiversity protection and conservation education in this century.
ContributorsLove, Karen (Author) / Minteer, Ben (Thesis advisor) / Kinzig, Ann (Committee member) / Collins, James (Committee member) / Arizona State University (Publisher)
Created2014
Description
In complex consumer-resource type systems, where diverse individuals are interconnected and interdependent, one can often anticipate what has become known as the tragedy of the commons, i.e., a situation, when overly efficient consumers exhaust the common resource, causing collapse of the entire population. In this dissertation I use mathematical modeling to explore different variations on the consumer-resource type systems, identifying some possible transitional regimes that can precede the tragedy of the commons. I then reformulate it as a game of a multi-player prisoner's dilemma and study two possible approaches for preventing it, namely direct modification of players' payoffs through punishment/reward and modification of the environment in which the interactions occur. I also investigate the questions of whether the strategy of resource allocation for reproduction or competition would yield higher fitness in an evolving consumer-resource type system and demonstrate that the direction in which the system will evolve will depend not only on the state of the environment but largely on the initial composition of the population. I then apply the developed framework to modeling cancer as an evolving ecological system and draw conclusions about some alternative approaches to cancer treatment.
ContributorsKareva, Irina (Author) / Castillo-Chavez, Carlos (Thesis advisor) / Collins, James (Committee member) / Nagy, John (Committee member) / Smith, Hal (Committee member) / Arizona State University (Publisher)
Created2012
Description
Despite years of effort, the field of conservation biology still struggles to incorporate theories of animal behavior. I introduce in Chapter I the issues surrounding the disconnect between behavioral ecology and conservation biology, and propose the use of behavioral knowledge in population viability analysis. In Chapter II, I develop a framework that uses three strategies for incorporating behavior into demographic models, outline the costs of each strategy through decision analysis, and build on previous work in behavioral ecology and demography. First, relevant behavioral mechanisms should be included in demographic models used for conservation decision-making. Second, I propose rapid behavioral assessment as a useful tool to approximate demographic rates through regression of demographic phenomena on observations of related behaviors. This technique provides behaviorally estimated parameters that may be applied to population viability analysis for use in management. Finally, behavioral indices can be used as warning signs of population decline. The proposed framework combines each strategy through decision analysis to provide quantitative rules that determine when incorporating aspects of conservation behavior may be beneficial to management. Chapter III applies this technique to estimate birthrate in a colony of California sea lions in the Gulf of California, Mexico. This study includes a cost analysis of the behavioral and traditional parameter estimation techniques. I then provide in Chapter IV practical recommendations for applying this framework to management programs along with general guidelines for the development of rapid behavioral assessment.
ContributorsWildermuth, Robert (Author) / Gerber, Leah R. (Thesis advisor) / Collins, James (Committee member) / Smith, Andrew (Committee member) / Arizona State University (Publisher)
Created2012
Description
Evolution is the foundation of biology, yet it remains controversial even among college biology students. Acceptance of evolution is important for students if we want them to incorporate evolution into their scientific thinking. However, students’ religious beliefs are a consistent barrier to their acceptance of evolution due to a perceived conflict between religion and evolution. Using pre-post instructional surveys of students in introductory college biology, Study 1 establishes instructional strategies that can be effective for reducing students' perceived conflict between religion and evolution. Through interviews and qualitative analyses, Study 2 documents how instructors teaching evolution at public universities may be resistant towards implementing strategies that can reduce students' perceived conflict, perhaps because of their own lack of religious beliefs and lack of training and awareness about students' conflict with evolution. Interviews with religious students in Study 3 reveals that religious college biology students can perceive their instructors as unfriendly towards religion which can negatively impact these students' perceived conflict between religion and evolution. Study 4 explores how instructors at Christian universities, who share the same Christian backgrounds as their students, do not struggle with implementing strategies that reduce students' perceived conflict between religion and evolution. Cumulatively, these studies reveal a need for a new instructional framework for evolution education that takes into account the religious cultural difference between instructors who are teaching evolution and students who are learning evolution. As such, a new instructional framework is then described, Religious Cultural Competence in Evolution Education (ReCCEE), that can help instructors teach evolution in a way that can reduce students' perceived conflict between religion and evolution, increase student acceptance of evolution, and create more inclusive college biology classrooms for religious students.
ContributorsBarnes, Maryann Elizabeth (Author) / Brownell, Sara (Thesis advisor) / Nesse, Randolph (Committee member) / Collins, James (Committee member) / Husman, Jenefer (Committee member) / Maienschein, Jane (Committee member) / Arizona State University (Publisher)
Created2018
Description
Guided by Tinto’s Theory of College Student Departure, I conducted a set of five studies to identify factors that influence students’ social integration in college science active learning classes. These studies were conducted in large-enrollment college science courses and some were specifically conducted in undergraduate active learning biology courses. Using qualitative and quantitative methodologies, I identified how students’ identities, such as their gender and LGBTQIA identity, and students’ perceptions of their own intelligence influence their experience in active learning science classes and consequently their social integration in college. I also determined factors of active learning classrooms and instructor behaviors that can affect whether students experience positive or negative social integration in the context of active learning. I found that students’ hidden identities, such as the LGBTQIA identity, are more relevant in active learning classes where students work together and that the increased relevance of one’s identity can have a positive and negative impact on their social integration. I also found that students’ identities can predict their academic self-concept, or their perception of their intelligence as it compares to others’ intelligence in biology, which in turn predicts their participation in small group-discussion. While many students express a fear of negative evaluation, or dread being evaluated negatively by others when speaking out in active learning classes, I identified that how instructors structure group work can cause students to feel more or less integrated into the college science classroom. Lastly, I identified tools that instructors can use, such as name tents and humor, which can positive affect students’ social integration into the college science classroom. In sum, I highlight inequities in students’ experiences in active learning science classrooms and the mechanisms that underlie some of these inequities. I hope this work can be used to create more inclusive undergraduate active learning science courses.
ContributorsCooper, Katelyn M (Author) / Brownell, Sara E (Thesis advisor) / Stout, Valerie (Committee member) / Collins, James (Committee member) / Orchinik, Miles (Committee member) / Zheng, Yi (Committee member) / Arizona State University (Publisher)
Created2018
Description
Recognizing that CEOs are less capable of diversifying their employment risks than shareholders who could diversify their investment risks through portfolio investments, agency theory assumes that CEOs tend to be risk averse compared with shareholders. Based on this assumption, agency theory scholars suggest that to align the risk preference of CEOs with that of shareholders, CEOs need to be closely monitored and have less power. SEC regulators have been adopting the suggestion and accordingly CEO power has been reduced in the past decades. However, the empirical results are mixed and cannot provide solid support for the suggestion that reducing CEO power could lead the CEO to take more risks.
Considering that managerial risk taking is an important issue in strategic management research and agency theory has been widely adopted in academia and business worlds, it is imperative to clarify the mechanism behind the relationship between CEO power and risk taking. My study aims to fill this research gap. In this study I follow agency theory to take an employment security perspective and fully consider how CEOs’ concern about employment security is affected by their power and ownership structure to enrich the understanding of the effects of CEO power and ownership structure on risk taking. I fine-tune the key concept CEO power into the CEO power over board and introduce a key aspect of ownership structure - nontransient investor ownership. I further suggest that CEO power over board and nontransient investor ownership affect CEOs’ employment security and the resulting CEO risk taking. In addition, I consider a set of industry and firm characteristics as the boundary conditions for the effects of CEO power and nontransient investor ownership on CEO risk-taking. This set of industry and firm characteristics include industry complexity, industry dynamism, industry munificence and firm slack.
I test my theory using a large-scale, multi-year sample of U.S. publicly listed S&P 1500 firms between 2001 and 2017. My main hypotheses about the effects of CEO power over board and nontransient investor ownership on CEO risk taking receive strong support.
Considering that managerial risk taking is an important issue in strategic management research and agency theory has been widely adopted in academia and business worlds, it is imperative to clarify the mechanism behind the relationship between CEO power and risk taking. My study aims to fill this research gap. In this study I follow agency theory to take an employment security perspective and fully consider how CEOs’ concern about employment security is affected by their power and ownership structure to enrich the understanding of the effects of CEO power and ownership structure on risk taking. I fine-tune the key concept CEO power into the CEO power over board and introduce a key aspect of ownership structure - nontransient investor ownership. I further suggest that CEO power over board and nontransient investor ownership affect CEOs’ employment security and the resulting CEO risk taking. In addition, I consider a set of industry and firm characteristics as the boundary conditions for the effects of CEO power and nontransient investor ownership on CEO risk-taking. This set of industry and firm characteristics include industry complexity, industry dynamism, industry munificence and firm slack.
I test my theory using a large-scale, multi-year sample of U.S. publicly listed S&P 1500 firms between 2001 and 2017. My main hypotheses about the effects of CEO power over board and nontransient investor ownership on CEO risk taking receive strong support.
ContributorsZhu, Qi (Author) / Shen, Wei (Thesis advisor) / Zhu, David (Thesis advisor) / Certo, Trevis (Committee member) / Arizona State University (Publisher)
Created2019
Description
The purpose of this study was to observe the effectiveness of the phenylalanyl arginine β-naphthylamide dihydrochloride inhibitor and Tween 20 when combined with an antibiotic against Escherichia. coli. As antibiotic resistance becomes more and more prevalent it is necessary to think outside the box and do more than just increase the dosage of currently prescribed antibiotics. This study attempted to combat two forms of antibiotic resistance. The first is the AcrAB efflux pump which is able to pump antibiotics out of the cell. The second is the biofilms that E. coli can form. By using an inhibitor, the pump should be unable to rid itself of an antibiotic. On the other hand, using Tween allows for biofilm formation to either be disrupted or for the biofilm to be dissolved. By combining these two chemicals with an antibiotic that the efflux pump is known to expel, low concentrations of each chemical should result in an equivalent or greater effect on bacteria compared to any one chemical in higher concentrations. To test this hypothesis a 96 well plate BEC screen test was performed. A range of antibiotics were used at various concentrations and with varying concentrations of both Tween and the inhibitor to find a starting point. Following this, Erythromycin and Ciprofloxacin were picked as the best candidates and the optimum range of the antibiotic, Tween, and inhibitor were established. Finally, all three chemicals were combined to observe the effects they had together as opposed to individually or paired together. From the results of this experiment several conclusions were made. First, the inhibitor did in fact increase the effectiveness of the antibiotic as less antibiotic was needed if the inhibitor was present. Second, Tween showed an ability to prevent recovery in the MBEC reading, showing that it has the ability to disrupt or dissolve biofilms. However, Tween also showed a noticeable decrease in effectiveness in the overall treatment. This negative interaction was unable to be compensated for when using the inhibitor and so the hypothesis was proven false as combining the three chemicals led to a less effective treatment method.
ContributorsPetrovich Flynn, Chandler James (Author) / Misra, Rajeev (Thesis director) / Bean, Heather (Committee member) / Perkins, Kim (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
An in-depth analysis on the effects vortex generators cause to the boundary layer separation that occurs when an internal flow passes through a diffuser is presented. By understanding the effects vortex generators demonstrate on the boundary layer, they can be utilized to improve the performance and efficiencies of diffusers and other internal flow applications. An experiment was constructed to acquire physical data that could assess the change in performance of the diffusers once vortex generators were applied. The experiment consisted of pushing air through rectangular diffusers with half angles of 10, 20, and 30 degrees. A velocity distribution model was created for each diffuser without the application of vortex generators before modeling the velocity distribution with the application of vortex generators. This allowed the two results to be directly compared to one another and the improvements to be quantified. This was completed by using the velocity distribution model to find the partial mass flow rate through the outer portion of the diffuser's cross-sectional area. The analysis concluded that the vortex generators noticeably increased the performance of the diffusers. This was best seen in the performance of the 30-degree diffuser. Initially the diffuser experienced airflow velocities near zero towards the edges. This led to 0.18% of the mass flow rate occurring in the outer one-fourth portion of the cross-sectional area. With the application of vortex generators, this percentage increased to 5.7%. The 20-degree diffuser improved from 2.5% to 7.9% of the total mass flow rate in the outer portion and the 10-degree diffuser improved from 11.9% to 19.2%. These results demonstrate an increase in performance by the addition of vortex generators while allowing the possibility for further investigation on improvement through the design and configuration of these vortex generators.
ContributorsSanchez, Zachary Daniel (Author) / Takahashi, Timothy (Thesis director) / Herrmann, Marcus (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The objective of this project was to design an electrically driven centrifugal pump for the Daedalus Astronautics @ASU hybrid rocket engine (HRE). The pump design was purposefully simplified due to time, fabrication, calculation, and capability constraints, which resulted in a lower fidelity design, with the option to be improved later. The impeller, shroud, volute, shaft, motor, and ESC were the main focuses of the pump assembly, but the seals, bearings, lubrication methods, and flow path connections were considered as elements which would require future attention. The resulting pump design is intended to be used on the Daedalus Astronautics HRE test cart for design verification. In the future, trade studies and more detailed analyses should and will be performed before this pump is integrated into the Daedalus Astronautics flight-ready HRE.
ContributorsShillingburg, Ryan Carl (Author) / White, Daniel (Thesis director) / Brunacini, Lauren (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Human habitation of other planets requires both cost-effective transportation and low time-of-flight for human passengers and critical supplies. The current methods for interplanetary orbital transfers, such as the Hohmann transfer, require either expensive, high fuel maneuvers or extended space travel. However, by utilizing the high velocities of a super-geosynchronous space elevator, spacecraft released from an apex anchor could achieve interplanetary transfers with minimal Delta V fuel and time of flight requirements. By using Lambert’s Problem and Free Release propagation to determine the minimal fuel transfer from a terrestrial space elevator to Mars under a variety of initial conditions and time-of-flight constraints, this paper demonstrates that the use of a space elevator release can address both needs by dramatically reducing the time-of-flight and the fuel budget.
ContributorsTorla, James (Author) / Peet, Matthew (Thesis director) / Swan, Peter (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05