VictorJuiz/thesis huggingface dataset:
Electronic States of Heavy Fermion Materials

The de Haas-van Alphen (dHvA) effect is one of the most powerful and straightforward methods of determining the electronic structure of metals, knowledge of which is essential to understanding the observed physical properties such as resistivity, magnetic structure, and specific heat. Of interest in the field of condensed matter physics are the so-called heavy fermion materials: compounds involving rare earth metals in which strong correlation effects cause the electrons to behave as if they are orders of magnitude heavier than a bare electron. To enable measurement of these materials, I maintained our in-house data collection system known as DAVIES. Long standing issues in network communication between the involved computers have been mitigated or solved, improving the overall ease of measurement. Using DAVIES and our 3He/4He dilution refrigerator, I completed field modulation dHvA measurements on samples of YbRh2Si2 for field sweeps of 16-13 T and sample rotations from (100)-(110), (100)-(001), and (110)-(001). This yielded the first observation of an orbit that could be attributed to the J-sheet of the Fermi surface. The rotation measurements were compared against basic band structure calculations, which I completed, and more advanced band structure calculations. The calculations are in good agreement with the experimental results, though the ad hoc fitting method requires a more thorough examination to better understand the origin of this agreement. I also conducted field modulation dHvA measurements on one sample of PrOs4Sb12 for sweeps of 10-7 and 6-3 T at temperatures from about 25-2800 mK. A novel technique, which examines the phase of the quantum oscillations, was utilized to explore the occupancy of the Pr crystal field levels and the lower antiferroquadruploar (AFQ) phase boundary. These results were compared against mean field calculations, which took into account nearest neighbor quadrupolar coupling and the hyperfine interaction in the Hamiltonian. We obtained good agreement of the theoretical and experimental phase boundary, except at the lowest temperatures, in which a tail was predicted by calculations but not observed by experiment. This lead to the conclusion that further refinement of our mean field theory would be an interesting pursuit for future research into this material.

Keywords: de haas-van alphen effect
heavy fermion materials
quantum phase transitions
Advisor: Julian, Stephen R
Regulation of Chromosome Segregation and Cohesion by the deubiquitinase USP37

During the cell cycle, replicated chromosomes must remain paired until cell division in mitosis. This pairing is mediated by the conserved cohesin complex. During mitosis, a bipolar spindle facilitates the equal transmission of genetic material to two daughter cells. This fidelity in chromosome segregation protects cells against chromosomal instability and aneuploidy, which can contribute to development and progression of a variety of diseases, including cancer and Down syndrome. In this thesis, I present an RNA interference screen for novel regulators of bipolar spindle assembly, which led to the finding that the deubiquitinase USP37 regulates chromosome segregation during mitosis. Although the role of ubiquitin ligases (e.g. APC/C, SCF complex) in cell cycle regulation is known, the role of deubiquitinases is less well characterized. Accordingly, my thesis focuses on understanding the molecular mechanisms by which USP37 regulates chromosome segregation. In Chapter 3, I present evidence that USP37 regulates the NDC80 (HEC1) complex in kinetochore-microtubule attachment during chromosome segregation in mitosis. In Chapter 4, I present evidence that USP37 regulates chromatid cohesion. Specifically, USP37 regulates the deubiquitylation and stability of chromatin-associated WAPL, a protein required for removal of cohesin from chromosome arms in early mitosis. Collectively, the data presented in this thesis provide new insights into the regulation of mitotic chromosome segregation and cohesion by the ubiquitin proteasome system.

Keywords: cohesion
mitosis
mitotic spindle
USP37
Advisor: Pelletier, Laurence
Examination of Harmonics in Power Systems with Embedded Power Electronic Converters during Transients and Steady State

Rapid growth in the renewable energy sector and the upcoming growth of the electrical energy storage sector are resulting in an ever-growing number of grid-connected power converters. These converters inject harmonic currents into the grid that can lead to unacceptable levels of harmonic pollution during both transients and steady state. To study transient harmonics of power converters, the concept of generalized averaging has recently attracted considerable interest. Two distinct approaches have been employed in the literature to obtain dynamic harmonics. However, embedded in these approaches are restricting assumptions that have been overlooked by some researchers. This has resulted in several misconceptions and misapplications of models. This thesis determines implicit underlying assumptions and identifies appropriate and inappropriate areas of applications for these two approaches. A simple circuit is employed to clearly communicate ideas. To study steady state harmonics of power converters, few pragmatic tools presently exist for utilities to predict the impact of grid-connecting a new power converter or to assess the potential grid impact of one converter versus another. Converter data sheets contain insufficient information to make such determinations. It is generally known that the amount of harmonic injection depends not only on the background voltage harmonics, but also on the interactions that occur between the grid harmonic impedance and the converter. The thesis proposes new pragmatic techniques based on the frequency coupling matrix concept that permit accurate modeling and analysis of power converters, without requiring detailed information about the internal parameters of the converters. An online technique for identification of the frequency coupling matrix model of grid-connected converters is also proposed. Proposed techniques are verified through experimental measurements on a commercial, three phase, photovoltaic inverter.

Keywords: Electric Power Systems
Harmonics
Power Quality
Advisor: Lehn, Peter W
Content Analyses of Personal Emergency Response Calls: Towards a More Robust Spoken Dialogue-based Personal Emergency Response System

In an attempt to address identified usability barriers of traditional push-button-type personal emergency response systems, a novel automated, intelligent, spoken dialogue-based personal emergency response system is being developed. To design this system and make it more robust for end-users, further information, currently not available in research literature, is needed to improve the artificial intelligence and spoken dialogue components of the system. Using a mixed methods design, this dissertation describes three studies that derive this needed information from real personal emergency response calls. The first study identified 185 keywords and phrases spoken by system users; 17 categories for classifying keywords; and a personal emergency situation model including caller type, call reason, and risk level. The second study expanded the situation model to a personal emergency response model by adding a response-type classification. Various statistical analyses were applied to response calls using call classifications and select conversational measures. Significant trends in call data that could be used to pre-inform the automated personal emergency response system dialogue manager of a call's potential outcome were identified. Words per minute and turn length in words were found to be possible predictors of caller type. Emergency medical services were the predominant response requested for high risk calls and medium risk calls and non-professional responders appeared mainly in medium risk calls. Care provider and older adult callers were also found to employ different conversational strategies when responding to the call taker. In the third study, a spoken speech corpus was developed containing younger and older adult, actor simulated, spontaneous, read, and emotional speech, including personal emergency response keywords, phrases, and scenarios. Taken together, these research results will contribute towards the design and development of a more robust automated, personal emergency response system for older adults to help them age-in-place.

Keywords: aging-in-place
content analysis
older adult
personal emergency response
personal emergency response system
spoken dialogue system
Advisor: Mihailidis, Alex
Crystal Engineering of Boron Subphthalocyanine Derivatives Using Hydrogen and Halogen Bonding for Organic Electronic Applications

Boron subphthalocyanines (BsubPcs) are a class of aromatic bowl-shaped small molecules of interest for organic electronic applications such as organic solar cells. In solid state organic electronic devices, the orientation of the molecules and the spacing between them affect important material properties. In this thesis, the structure-property relationships between molecular structure, solid state arrangement and organic electronic device characteristics are explored for BsubPc derivatives. Hydrogen bonds and halogen bonds are of particular interest in the field of crystal engineering, due to the strength and directionality of these intermolecular interactions. The ability of BsubPcs to form hydrogen and halogen bonds was systematically explored. BsubPc derivatives which display either halogen or hydrogen bonds in their solid state arrangement were incorporated into organic solar cell devices and their thin film properties were studied in order to investigate the relationship between solid state arrangement and material properties.

Keywords: crystal engineering
halogen bonding
hydrogen bonding
organic photovoltaic
organic solar cell
subphthalocyanine
Advisor: Bender, Tim
A Digital Bundle: Exploring the Impact of Indigenous Knowledge Online Through FourDirectionsTeachings.com

Indigenous knowledge on the Internet is a new cultural form and therefore represents a new capacity for indigenous communities. This thesis examines how online indigenous knowledge sites mediate culture, knowledge, history and subjects into new forms and sets of social relationships (Poster, 1995). Specifically this thesis explores the potential of the Internet and digital technology to serve indigenous resurgence by contributing to the efforts and goals of indigenous nation building. Based on interviews and discussions with active users of FourDirectionsTeachings.com, a website that I created, I propose that online indigenous knowledge projects can be considered as “digital bundles.” Naming online indigenous knowledge projects in this way elevates the cultural protocol and cultural responsibilities that come with such a designation. In addition, the notion of digital bundle grounds online indigenous knowledge projects within an indigenous epistemological paradigm. Drawing on methodologies and concepts developed by indigenous, cultural studies and social movement scholars, and bridging the fields of indigenous resurgence and internet studies, this study contributes to new understandings on the role of indigenous knowledge and education in a networked world.

Keywords: Cultural practices
Decolonization
Indigenous Pedagogy
Indigenous Resurgence
Internet Activism
Knowledge production
Advisor: Dehli, Kari
Contrast-enhanced Doppler Ultrasound Imaging using Plane Waves

There is a clear advantage in having an imaging method that would be capable of displaying perfusion and vascular imaging simultaneously. In ultrasound, Doppler can visualize veins and arteries, but cannot detect the capillary level perfusion. Conversely, microbubble contrast-enhanced ultrasound imaging enables low velocity perfusion to be detected and separated from the tissue echo, but has a limited ability to depict the vascular morphology within the perfused tissue. To date, it has been challenging to combine these two methods due to realistic imaging time constraints severely limiting the number of pulses available for Doppler estimates. However, recent breakthroughs in plane-wave synthetic ultrasound considerably increased the maximal imaging frame rate, enabling new imaging trade-off previously unavailable. In this thesis, we first implement pulse inversion Doppler using plane-wave ultrasound and demonstrate the ability of the technique in segmenting fast from slow blood flow, which has applications, for example, in the detection, diagnosis and assessment of anti-angiogenic treatment of focal lesions. As the ability to differentiate perfusion from the tissue signal is limited by the contrast-to-tissue ratio achieved by the contrast-enhanced pulsing sequence, independently of the Doppler ensemble length, we develop a new Doppler sequence based on amplitude modulation (AM) which improves bubble detection specificity compared to conventional Pulse Inversion Doppler. We also demonstrate that modifying the pressure of the acoustic pulse (e.g. AM) introduces a characteristic phase delay in the microbubble echo, with no equivalent in tissue. A novel microbubble imaging scheme taking advantage of this behaviour is shown to further improve the contrast-to-tissue ratio. Lastly, while it is known that long Doppler acquisitions enable accurate velocity estimation in blood (hematocytes), microbubbles are only quasi-stable during repeated ultrasound exposure. Short acoustic pulses are helpful in mitigating microbubble destruction, but concurrently introduce a classical error associated to uncertainty limit of waves. Existing contrast agents are also polydispersed in their physical properties, which adds another degree of statistical randomness in the received echoes. In this work, we assess how these factors affect our ability to measure the velocity of flowing microbubbles.

Keywords: Doppler
Microbubble
Perfusion imaging
Plane-wave ultrasound
Vascular morphology
Advisor: Burns, Peter N
The Vibrochord: Investigating a Virboractile Musical Instrument

A novel device called the Vibrochord is proposed and validated for its use in the composition and production of vibrotactile music. Vibrotactile music is patterns of vibration applied to the skin rather than the ear. In the first of four studies, four audio music composers were recruited to offer suggestions for the design of the Vibrochord and to probe their composition style and process. Several design ideas that will be implemented in future versions of the Vibrochord were elicited. Attitudes about the Vibrochord and vibrotactile music seemed cautiously optimistic. In the second study participants were recruited to compare various aspects of the Vibrochord to the traditional piano keyboard. It seems that for playing short vibrotactile phrases the design of the Vibrochord allowed for an increase in player accuracy. In the third study, three artists composed a happy and sad vibrotactile song using the Vibrochord and Emoti-Chair. All composers were able to complete this task suggesting the Vibrochord is a viable tool for the composition and production of vibrotactile music. It seems that each artist thought similarly about what characteristics of vibrotactile music would convey the desired emotions. In the fourth study an audience rated the emotional content of the vibrotactile songs composed and produced in study three. All artists were successful in composing and producing vibrotactile music that conveyed the basic emotions of either happy or sad. It seems that notes per second, jumps per second, lengths per second, average note length and lengths per jump are primarily responsible for the conveyance of emotion. The fifth study had audiences rating the emotional content of short vibrotactile clips created using the fourth study as a guide. Notes per second, or "tempo", most likely plays a role in the conveyance of basic emotion. Note frequency also plays a role in this conveyance. Faster tempo songs with higher frequency notes were interpreted as conveying more happiness and vice versa. A regression model showing the relationship between emotional rating of a vibrotactile song and the songs notes per second and average note frequency is proposed.

Keywords: cross modal
human factors
music
tactile
vibrochord
vibrotactile
Advisor: Chignell, Mark
Fels, Deborah
Languages, Cultures and Identities of Newcomer Adolescent Learners: Deconstructing Multicultural Education in South Korea

Despite the South Korean government’s recent policy interventions to accommodate the emerging social and classroom reality that has increasingly become multicultural, few guidelines have been provided for multicultural education practice at the local and municipal levels in South Korea (Henceforth, Korea). In particular, investigations focusing on newcomer adolescents’ linguistic and cultural identities are scarce. In this light, this doctoral inquiry investigates how multicultural students, their languages and cultures are reflected in Korean society and schools and especially, how newcomer adolescents’ linguistic and cultural identities are negotiated in terms of their own success in Korea. 8 multicultural education policies and 27 news media publications as well as the narratives of 7 students and 6 educators from two high schools are analyzed through Fairclough’s (1992, 2003) critical discourse analysis. Based on the analysis, the discourses of diversity embedded in the nation-state texts and popular media as well as in the institutional contexts are discussed in relation to five orientations to diversity, which are derived from Ruiz’s (1984) theoretical framework of three orientations to language planning and Cummins’(2001) empowerment framework. The study reveals that an ideology of Korean ethnocentrism is reflected throughout the policy and news media articles as well as school administrators’ conceptualizations of diversity and multicultural education. Despite the emergent progressive orientations of viewing diversity as a right and resource, the predominant discourses of viewing diversity are that diversity is a problem/threat to society and is a problem/impediment to multicultural students’ social integration. It is evident that diversity is only appreciated once multicultural students are fully assimilated into Korean society. Thus, the notion of multicultural identity is absent or at best hidden in the Korean context. The study highlights that schools and policy makers need to make a shift in their orientations to diversity toward diversity as a right, resource and a form of empowerment through critical multicultural education in order to instill just and equitable worldviews in students. Educators’ negligence in considering these possibilities contributes to reproducing unequal power relations that disadvantage linguistic and cultural minorities and perpetuate the hegemonic status quo in Korean society.

Keywords: Critical Discourse Analysis
Diversity
Linguistic and Cultural Identity
Newcomer Youth
Policy and News Media Analysis
South Korea
Advisor: Cummins, James
Inductively-powered Implantable Integrated Circuits for Amperometric Brain Chemistry Monitoring

This dissertation presents the design of inductively-powered and powering circuits for implantable brain chemistry monitoring. It includes implantable integrated circuits designed for amperometric measurement of potassium and sodium ion concentrations, optimal design of the inductive powering links, power transfer systems, as well as the data transmission circuits to send the chip data to a nearby computer station. To optimally power the implanted chip, a comprehensive tutorial and design guide on low-absorption inductive links is presented. The conventional model of inductive power transfer is studied from a specific-absorption-rate (SAR) point of view. The model is analyzed in an optimization problem to find the optimal geometries of the transmitting and the receiving coils that result in the highest delivered to absorbed power (in tissue) ratio. These results are then compared with the power-transfer-efficiency (PTE) optimization results, which concludes that the two are distinct. The complete design of an inductive powering system is then presented for an in vivo free-moving animal experiment. The system offers a significantly improved power delivery to tissue absorption, a low-cost scalable architecture to cover large areas, as well as a low-cost receiver localization technique based on an impedance tracking algorithm. To communicate data from the high-throughput implantable microarray to a benchtop receiver, a power-efficient, ultra-wideband pulse radio (UWB-IR) transmitter is presented. While the conventional UWB-IR transmitters use transient response of an LC tank, the LC tank in this design works in the steady state. This results in a significantly improved power efficiency. The resulting efficiency is comparable to those of the latest published power-efficient Bluetooth transmitters. Finally, the implantable integrated circuits for the in vivo measurement of sodium and potassium are presented. These components include microelectrodes covered with the anti-fouling monolayer (Monoethylene glycolated (MEG) OH), ultra-low-power potentiostats, and the peripheral circuits to power, configure and operate the potentiostats. An op-amp-less-ADC design is proposed to reduce the energy consumption of the potentiostats, without compromising their sensitivity. This design allows for larger potentiostat arrays to be powered with the limited power budget of the implantable chip which enables higher spatial resolution electrochemical monitoring.

Advisor: Genov, Roman
Contrastive Representations in Non-segmental Phonology

This thesis develops and tests a unified model of word-level prosodic contrasts. Traditionally, word prosody has been analyzed within disparate models (such as autosegmental theory for tone, metrical theory for stress, and CV, X-slot, or moraic theory for length), meaning that it has not been possible to make clear predictions about how many different prosodic features can be employed in a single language. I present a minimal architecture for word prosodic representations based on a single set of formal elements. A tier of segmental root nodes, or X-slots, bears the binary contrastive features that divide the segmental inventory and represents quantity contrasts through two-to-one linking, while a tier of prosodic root nodes, or "pi-nodes", bears the binary features dividing the autosegmental inventory. Features on pi-nodes are used in tone languages with more than one tonal autosegment, but in privative tone languages, the pi-node itself reflects the phonetic realization of the marked member of the tone opposition. The same featureless pi-node is used as an autosegmental marker of accented positions in lexical stress systems, where its language-specific phonetic realization is that of stress: some combination of increased pitch, duration, and intensity. The predictive power of this model is that it restricts systems to a maximum of two independent word prosodic contrasts, since each requires its own tier of root nodes. The pi-tier can represent either tone or accent separately from length on the X-tier, but this leaves no means to represent a third contrast. In certain systems, surface stress may be represented covertly as length on the X-tier with tone represented on the pi-tier, but no mechanism is available to host a third contrast, since the X-tier is already used for stress.

Keywords: contrast
length
phonology
prosody
stress
tone
Advisor: Dresher, B Elan