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Description
The 23-step total synthesis of dolastatin 16, a cyclic depsipeptide of marine origin, is presented. Included are syntheses of nonnatural amino acids dolamethylleuine and dolaphenvaline. The biological activity of the synthetic product differed from naturally isolated dolastatin 16, which may indicate the initial screening identified an inactive compound and the

The 23-step total synthesis of dolastatin 16, a cyclic depsipeptide of marine origin, is presented. Included are syntheses of nonnatural amino acids dolamethylleuine and dolaphenvaline. The biological activity of the synthetic product differed from naturally isolated dolastatin 16, which may indicate the initial screening identified an inactive compound and the active one was not detected initially, or may be a result of the conformational dynamics induced by the proline residues. Additionally, a family of structural analogues to the bacillistatins, another cyclic marine depsipeptide, were synthesized. These were deemed the silstatins. 8 modifications were produced. The alterations aimed to introduce a heteroatomic residue for further derivatization, such as producing an antibody-drug conjugate. This introduction did in general decrease the neoplastic activity of these agents, as expected, but by modulating the lipophilicity of the compound we were able to salvage much of the potency of the bacillistatins while potentially allowing prodrug development.
ContributorsMacdonald, Christian B. (Author) / Pettit, George (Thesis director) / Wang, Xu (Committee member) / Melody, Noeleen (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2015-05
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Description
We develop the mathematical tools necessary to describe the interaction between a resonant pole and a threshold energy. Using these tools, we analyze the properties an opening threshold has on the resonant pole mass (the "cusp effect"), leading to an effect called "pole-dragging." We consider two models for resonances: a

We develop the mathematical tools necessary to describe the interaction between a resonant pole and a threshold energy. Using these tools, we analyze the properties an opening threshold has on the resonant pole mass (the "cusp effect"), leading to an effect called "pole-dragging." We consider two models for resonances: a molecular, mesonic model, and a color-nonsinglet diquark plus antidiquark model. Then, we compare the pole-dragging effect due to these models on the masses of the f0(980), the X(3872), and the Zb(10610) and compare the effect's magnitude. We find that, while for lower masses, such as the f 0 (980), the pole-dragging effect that arises from the molecular model is more significant, the diquark model's pole-dragging effect becomes dominant at higher masses such as those of the X(3872) and the Z b (10610). This indicates that for lower threshold energies, diquark models may have less significant effects on predicted resonant masses than mesonic models, but for higher threshold energies, it is necessary to include the pole-dragging effect due to a diquark threshold in high-precision QCD calculations.
ContributorsBlitz, Samuel Harris (Author) / Richard, Lebed (Thesis director) / Comfort, Joseph (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2015-05
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Description
Understanding damage evolution, particularly as it relates to local nucleation and growth kinetics of spall failure in metallic materials subjected to shock loading, is critical to national security. This work uses computational modeling to elucidate what characteristics have the highest impact on damage localization at the microstructural level in metallic

Understanding damage evolution, particularly as it relates to local nucleation and growth kinetics of spall failure in metallic materials subjected to shock loading, is critical to national security. This work uses computational modeling to elucidate what characteristics have the highest impact on damage localization at the microstructural level in metallic materials, since knowledge of these characteristics is critical to improve these materials. The numerical framework consists of a user-defined material model implemented in a user subroutine run in ABAQUS/Explicit that takes into account crystal plasticity, grain boundary effects, void nucleation and initial growth, and both isotropic and kinematic hardening to model incipient spall. Finite element simulations were performed on copper bicrystal models to isolate the boundary effects between two grains. Two types of simulations were performed in this work: experimentally verified cases in order to validate the constitutive model as well as idealized cases in an attempt to determine the microstructural characteristic that define weakest links in terms of spall damage. Grain boundary effects on damage localization were studied by varying grain boundary orientation in respect to the shock direction and the crystallographic properties of each grain in the bicrystal. Varying these parameters resulted in a mismatch in Taylor factor across the grain boundary and along the shock direction. The experimentally verified cases are models of specific damage sites found from flyer plate impact tests on copper multicrystals in which the Taylor factor mismatch across the grain boundary and along the shock direction are both high or both low. For the idealized cases, grain boundary orientation and crystallography of the grains are chosen such that the Taylor factor mismatch in the grain boundary normal and along the shock direction are maximized or minimized. A perpendicular grain boundary orientation in respect to the shock direction maximizes Taylor factor mismatch, while a parallel grain boundary minimizes the mismatch. Furthermore, it is known that <1 1 1> crystals have the highest Taylor factor, while <0 0 1> has nearly the lowest Taylor factor. The permutation of these extremes for mismatch in the grain boundary normal and along the shock direction results in four idealized cases that were studied for this work. Results of the simulations demonstrate that the material model is capable of predicting damage localization, as it has been able to reproduce damage sites found experimentally. However, these results are qualitative since further calibration is still required to produce quantitatively accurate results. Moreover, comparisons of results for void nucleation rate and void growth rate suggests that void nucleation is more influential in the total void volume fraction for bicrystals with high property mismatch across the interface, suggesting that nucleation is the dominant characteristic in the propagation of damage in the material. Further work in recalibrating the simulation parameters and modeling different bicrystal orientations must be done to verify these results.
ContributorsVo, Johnathan Hiep (Author) / Peralta, Pedro (Thesis director) / Oswald, Jay (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2014-12
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Description
Mathematics is an increasingly critical subject and the achievement of students in mathematics has been the focus of many recent reports and studies. However, few studies exist that both observe and discuss the specific teaching and assessment techniques employed in the classrooms across multiple countries. The focus of this study

Mathematics is an increasingly critical subject and the achievement of students in mathematics has been the focus of many recent reports and studies. However, few studies exist that both observe and discuss the specific teaching and assessment techniques employed in the classrooms across multiple countries. The focus of this study is to look at classrooms and educators across six high achieving countries to identify and compare teaching strategies being used. In Finland, Hong Kong, Japan, New Zealand, Singapore, and Switzerland, twenty educators were interviewed and fourteen educators were observed teaching. Themes were first identified by comparing individual teacher responses within each country. These themes were then grouped together across countries and eight emerging patterns were identified. These strategies include students active involvement in the classroom, students given written feedback on assessments, students involvement in thoughtful discussion about mathematical concepts, students solving and explaining mathematics problems at the board, students exploring mathematical concepts either before or after being taught the material, students engagement in practical applications, students making connections between concepts, and students having confidence in their ability to understand mathematics. The strategies identified across these six high achieving countries can inform educators in their efforts of increasing student understanding of mathematical concepts and lead to an improvement in mathematics performance.
ContributorsAnglin, Julia Mae (Author) / Middleton, James (Thesis director) / Vicich, James (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2014-12
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Description
Covering subsequences with sets of permutations arises in many applications, including event-sequence testing. Given a set of subsequences to cover, one is often interested in knowing the fewest number of permutations required to cover each subsequence, and in finding an explicit construction of such a set of permutations that has

Covering subsequences with sets of permutations arises in many applications, including event-sequence testing. Given a set of subsequences to cover, one is often interested in knowing the fewest number of permutations required to cover each subsequence, and in finding an explicit construction of such a set of permutations that has size close to or equal to the minimum possible. The construction of such permutation coverings has proven to be computationally difficult. While many examples for permutations of small length have been found, and strong asymptotic behavior is known, there are few explicit constructions for permutations of intermediate lengths. Most of these are generated from scratch using greedy algorithms. We explore a different approach here. Starting with a set of permutations with the desired coverage properties, we compute local changes to individual permutations that retain the total coverage of the set. By choosing these local changes so as to make one permutation less "essential" in maintaining the coverage of the set, our method attempts to make a permutation completely non-essential, so it can be removed without sacrificing total coverage. We develop a post-optimization method to do this and present results on sequence covering arrays and other types of permutation covering problems demonstrating that it is surprisingly effective.
ContributorsMurray, Patrick Charles (Author) / Colbourn, Charles (Thesis director) / Czygrinow, Andrzej (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor)
Created2014-12
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Description
Rainbow Connection is an integrated choir with members on and off the autism spectrum. It was founded in the spring of 2012 by Barrett students Ali Friedman, Megan Howell, and Victoria Gilman as part of an honors thesis creative project. Rainbow Connection uses the rehearsal process and other creative endeavors

Rainbow Connection is an integrated choir with members on and off the autism spectrum. It was founded in the spring of 2012 by Barrett students Ali Friedman, Megan Howell, and Victoria Gilman as part of an honors thesis creative project. Rainbow Connection uses the rehearsal process and other creative endeavors to foster natural relationship building across social gaps. A process-oriented choir, Rainbow Connection's main goals concern the connections made throughout the experience rather than the final musical product. The authors believe that individual, non-hierarchical relationships are the keys to breaking down systemized gaps between identity groups and that music is an ideal facilitator for fostering such relationships. Rainbow Connection operates under the premise that, like colors in a rainbow, choir members create something beautiful not by melding into one homogenous group, but by collaboratively showcasing their individual gifts. This paper will highlight the basic premise and structure of Rainbow Connection, outline the process of enacting the choir, and describe the authors' personal reactions and takeaways from the project.
ContributorsFriedman, Alexandra (Co-author) / Gilman, Victoria (Co-author) / Howell, Megan (Co-author) / Rio, Robin (Thesis director) / Schildkret, David (Committee member) / Barrett, The Honors College (Contributor) / School of Music (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2014-12
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Description
The title means nothing because the stories have little in common, aside from the fact that I wrote them. The common theme of anxiety was unintentional, though it is prevalent in the stories, poetry and my life. Each story is written from a different style, with a different interest in

The title means nothing because the stories have little in common, aside from the fact that I wrote them. The common theme of anxiety was unintentional, though it is prevalent in the stories, poetry and my life. Each story is written from a different style, with a different interest in mind. The poetry that breaks up the stories is mine, and also free of common bonds. People whom I love inspired some of them; others stem from people with whom I was (or still am) angry. Some of them are just me trying to write poetry like other successful poets, who seem to know something I don't. I wrote this set of stories and poems because I wanted to see if I could do it. I wanted to challenge myself in a new medium (two new mediums really, if you separate literature and poetry). I wanted to prove to myself that I could do it, if I really set my mind to it. I wanted to have some wealth of words, which I could record myself reading. Overall, I hope that you enjoy these stories and words. I wrote them to entertain myself, and they seem to do that pretty well. If you don't like them, stop reading. If you do like them, keep reading and tell everyone you know about this collection. I'm proud of my work here, so anything beyond that is icing on my cake.
ContributorsRagatz, Zachariah Edward (Author) / Scott, Jason Davids (Thesis director) / Espinosa, Micha (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / School of Film, Dance and Theatre (Contributor)
Created2015-05
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Description
Bots tamper with social media networks by artificially inflating the popularity of certain topics. In this paper, we define what a bot is, we detail different motivations for bots, we describe previous work in bot detection and observation, and then we perform bot detection of our own. For our bot

Bots tamper with social media networks by artificially inflating the popularity of certain topics. In this paper, we define what a bot is, we detail different motivations for bots, we describe previous work in bot detection and observation, and then we perform bot detection of our own. For our bot detection, we are interested in bots on Twitter that tweet Arabic extremist-like phrases. A testing dataset is collected using the honeypot method, and five different heuristics are measured for their effectiveness in detecting bots. The model underperformed, but we have laid the ground-work for a vastly untapped focus on bot detection: extremist ideal diffusion through bots.
ContributorsKarlsrud, Mark C. (Author) / Liu, Huan (Thesis director) / Morstatter, Fred (Committee member) / Barrett, The Honors College (Contributor) / Computing and Informatics Program (Contributor) / Computer Science and Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2015-05
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Description
Adopting smart city tactics is important because it allows cities to develop sustainable communities through efficient policy initiatives. This study exemplifies how data analytics enables planners within smart cities to gain a better understanding of their population, and can make more informed choices based on these consumer choices. As a

Adopting smart city tactics is important because it allows cities to develop sustainable communities through efficient policy initiatives. This study exemplifies how data analytics enables planners within smart cities to gain a better understanding of their population, and can make more informed choices based on these consumer choices. As a rising share of the millennial generation enters the workforce, cities across the world are developing policy initiatives in the hopes of attracting these highly educated individuals. Due to this generation's strength in driving regional economic vitality directly and indirectly, it is in the best interests of city planners to understand the preferences of millennials so this information can be used to improve the attractiveness of communities for this high-purchasing power, productive segment of the population. Past research has revealed a tendency within this demographic to make location decisions based on the degree of ‘livability’ in an area. This degree represents a holistic approach at defining quality of life through the interconnectedness of both the built and social environments in cities.

Due to the importance of millennials to cities around the globe, this study uses 2010 ZIP code area data and the Phoenix metropolitan area as a case study to test the relationships between thirteen parameters of livability and the presence of millennials after controlling for other correlates of millennial preference.

The results of a multiple regression model indicated a positive linear association between livability parameters within smart cities and the presence of millennials. Therefore, the selected parameters of livability within smart cities are significant measures in influencing location decisions made by millennials. Urban planners can consequently increase the likelihood in which millennials will choose to live in a given area by improving livability across the parameters exemplified in this study. This mutually beneficial relationship provides added support to the notion that planners should develop solutions to improve livability within smart cities.
Created2015-05
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Description
Deconvolution of noisy data is an ill-posed problem, and requires some form of regularization to stabilize its solution. Tikhonov regularization is the most common method used, but it depends on the choice of a regularization parameter λ which must generally be estimated using one of several common methods. These methods

Deconvolution of noisy data is an ill-posed problem, and requires some form of regularization to stabilize its solution. Tikhonov regularization is the most common method used, but it depends on the choice of a regularization parameter λ which must generally be estimated using one of several common methods. These methods can be computationally intensive, so I consider their behavior when only a portion of the sampled data is used. I show that the results of these methods converge as the sampling resolution increases, and use this to suggest a method of downsampling to estimate λ. I then present numerical results showing that this method can be feasible, and propose future avenues of inquiry.
ContributorsHansen, Jakob Kristian (Author) / Renaut, Rosemary (Thesis director) / Cochran, Douglas (Committee member) / Barrett, The Honors College (Contributor) / School of Music (Contributor) / Economics Program in CLAS (Contributor) / School of Mathematical and Statistical Sciences (Contributor)
Created2015-05