Matching Items (21)
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- Genre: Masters Thesis
- Creators: Arizona State University
- Member of: ASU Electronic Theses and Dissertations
Description
Efficiency of components is an ever increasing area of importance to portable applications, where a finite battery means finite operating time. Higher efficiency devices need to be designed that don't compromise on the performance that the consumer has come to expect. Class D amplifiers deliver on the goal of increased efficiency, but at the cost of distortion. Class AB amplifiers have low efficiency, but high linearity. By modulating the supply voltage of a Class AB amplifier to make a Class H amplifier, the efficiency can increase while still maintaining the Class AB level of linearity. A 92dB Power Supply Rejection Ratio (PSRR) Class AB amplifier and a Class H amplifier were designed in a 0.24um process for portable audio applications. Using a multiphase buck converter increased the efficiency of the Class H amplifier while still maintaining a fast response time to respond to audio frequencies. The Class H amplifier had an efficiency above the Class AB amplifier by 5-7% from 5-30mW of output power without affecting the total harmonic distortion (THD) at the design specifications. The Class H amplifier design met all design specifications and showed performance comparable to the designed Class AB amplifier across 1kHz-20kHz and 0.01mW-30mW. The Class H design was able to output 30mW into 16Ohms without any increase in THD. This design shows that Class H amplifiers merit more research into their potential for increasing efficiency of audio amplifiers and that even simple designs can give significant increases in efficiency without compromising linearity.
ContributorsPeterson, Cory (Author) / Bakkaloglu, Bertan (Thesis advisor) / Barnaby, Hugh (Committee member) / Kiaei, Sayfe (Committee member) / Arizona State University (Publisher)
Created2013
Description
Given the process of tumorigenesis, biological signaling pathways have become of interest in the field of oncology. Many of the regulatory mechanisms that are altered in cancer are directly related to signal transduction and cellular communication. Thus, identifying signaling pathways that have become deregulated may provide useful information to better understanding altered regulatory mechanisms within cancer. Many methods that have been created to measure the distinct activity of signaling pathways have relied strictly upon transcription profiles. With advancements in comparative genomic hybridization techniques, copy number data has become extremely useful in providing valuable information pertaining to the genomic landscape of cancer. The purpose of this thesis is to develop a methodology that incorporates both gene expression and copy number data to identify signaling pathways that have become deregulated in cancer. The central idea is that copy number data may significantly assist in identifying signaling pathway deregulation by justifying the aberrant activity being measured in gene expression profiles. This method was then applied to four different subtypes of breast cancer resulting in the identification of signaling pathways associated with distinct functionalities for each of the breast cancer subtypes.
ContributorsTrevino, Robert (Author) / Kim, Seungchan (Thesis advisor) / Ringner, Markus (Committee member) / Liu, Huan (Committee member) / Arizona State University (Publisher)
Created2011
Description
In recent years, the field of nanomedicine has progressed at an astonishing rate, particularly with respect to applications in cancer treatment and molecular imaging. Although organic systems have been the frontrunners, inorganic systems have also begun to show promise, especially those based upon silica and magnetic nanoparticles (NPs). Many of these systems are being designed for simultaneous therapeutic and diagnostic capabilities, thus coining the term, theranostics. A unique class of inorganic systems that shows great promise as theranostics is that of layered double hydroxides (LDH). By synthesis of a core/shell structures, e.g. a gold nanoparticle (NP) core and LDH shell, the multifunctional theranostic may be developed without a drastic increase in the structural complexity. To demonstrate initial proof-of-concept of a potential (inorganic) theranostic platform, a Au-core/LDH-shell nanovector has been synthesized and characterized. The LDH shell was heterogeneously nucleated and grown on the surface of silica coated gold NPs via a coprecipitation method. Polyethylene glycol (PEG) was introduced in the initial synthesis steps to improve crystallinity and colloidal stability. Additionally, during synthesis, fluorescein isothiocyanate (FITC) was intercalated into the interlayer spacing of the LDH. In contrast to the PEG stabilization, a post synthesis citric acid treatment was used as a method to control the size and short-term stability. The heterogeneous core-shell system was characterized with scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), dynamic light scattering (DLS), and powder x-ray diffraction (PXRD). A preliminary in vitro study carried out with the assistance of Dr. Kaushal Rege's group at Arizona State University was to demonstrate the endocytosis capability of homogeneously-grown LDH NPs. The DLS measurements of the core-shell NPs indicated an average particle size of 212nm. The PXRD analysis showed that PEG greatly improved the crystallinity of the system while simultaneously preventing aggregation of the NPs. The preliminary in vitro fluorescence microscopy revealed a moderate uptake of homogeneous LDH NPs into the cells.
ContributorsRearick, Colton (Author) / Dey, Sandwip K (Thesis advisor) / Krause, Stephen (Committee member) / Ramakrishna, B (Committee member) / Arizona State University (Publisher)
Created2011
Description
Class D Amplifiers are widely used in portable systems such as mobile phones to achieve high efficiency. The demands of portable electronics for low power consumption to extend battery life and reduce heat dissipation mandate efficient, high-performance audio amplifiers. The high efficiency of Class D amplifiers (CDAs) makes them particularly attractive for portable applications. The Digital class D amplifier is an interesting solution to increase the efficiency of embedded systems. However, this solution is not good enough in terms of PWM stage linearity and power supply rejection. An efficient control is needed to correct the error sources in order to get a high fidelity sound quality in the whole audio range of frequencies. A fundamental analysis on various error sources due to non idealities in the power stage have been discussed here with key focus on Power supply perturbations driving the Power stage of a Class D Audio Amplifier. Two types of closed loop Digital Class D architecture for PSRR improvement have been proposed and modeled. Double sided uniform sampling modulation has been used. One of the architecture uses feedback around the power stage and the second architecture uses feedback into digital domain. Simulation & experimental results confirm that the closed loop PSRR & PS-IMD improve by around 30-40 dB and 25 dB respectively.
ContributorsChakraborty, Bijeta (Author) / Bakkaloglu, Bertan (Thesis advisor) / Garrity, Douglas (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2012
Description
Cancer claims hundreds of thousands of lives every year in US alone. Finding ways for early detection of cancer onset is crucial for better management and treatment of cancer. Thus, biomarkers especially protein biomarkers, being the functional units which reflect dynamic physiological changes, need to be discovered. Though important, there are only a few approved protein cancer biomarkers till date. To accelerate this process, fast, comprehensive and affordable assays are required which can be applied to large population studies. For this, these assays should be able to comprehensively characterize and explore the molecular diversity of nominally "single" proteins across populations. This information is usually unavailable with commonly used immunoassays such as ELISA (enzyme linked immunosorbent assay) which either ignore protein microheterogeneity, or are confounded by it. To this end, mass spectrometric immuno assays (MSIA) for three different human plasma proteins have been developed. These proteins viz. IGF-1, hemopexin and tetranectin have been found in reported literature to show correlations with many diseases along with several carcinomas. Developed assays were used to extract entire proteins from plasma samples and subsequently analyzed on mass spectrometric platforms. Matrix assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometric techniques where used due to their availability and suitability for the analysis. This resulted in visibility of different structural forms of these proteins showing their structural micro-heterogeneity which is invisible to commonly used immunoassays. These assays are fast, comprehensive and can be applied in large sample studies to analyze proteins for biomarker discovery.
ContributorsRai, Samita (Author) / Nelson, Randall (Thesis advisor) / Hayes, Mark (Thesis advisor) / Borges, Chad (Committee member) / Ros, Alexandra (Committee member) / Arizona State University (Publisher)
Created2012
Description
Patients who attend genetic counseling appointments report high anxiety and varied satisfaction levels following their appointments. It has been suggested in previous literature that some of the increase in anxiety and reduction in satisfaction is caused by lack of prior information. Here, I investigated whether providing patients with a glossary of genetic terms prior to their counseling appointment improves patient satisfaction and reduces anxiety in an oncology genetic counseling appointment. I surveyed 96 patients attending their first genetic counseling appointment at Banner MD Anderson Cancer Center and analyzed 92 patients for which I had complete data. Patients were randomly selected to receive one of two folders, containing either an educational document or an educational document and a glossary comprised of ten genetic terms. Each patient was given a post-counseling survey at the end of the counseling appointment to assess their anxiety and satisfaction levels. I did not observe a statistically significant difference in levels of anxiety or satisfaction, but the data are consistent with increased satisfaction for patients who received a glossary. Interesting, the data are also consistent with decreased anxiety levels for patients who did not receive a glossary. Furthermore, I did observe differences in reported satisfaction with patients who had college experience and patients that did not have any college experience.
ContributorsPeon, Lidia Maria (Author) / Wilson Sayres, Melissa A (Thesis advisor) / Buetow, Kenneth H (Committee member) / Luiten, Rebecca C (Committee member) / Siettmann, Jennifer M (Committee member) / Arizona State University (Publisher)
Created2018
Description
Prophylactic bilateral mastectomy (PBM) is the current recommended course of action for women with increased genetic risk for breast and ovarian cancer. Nevertheless, many receive negative feedback from family and friends surrounding the decision to undergo this surgery because they do not have cancer when the decision is made; this results in a limited support network for coping with their PBM. Low social support is associated with depression, negativity, and anxiety. Women who had a PBM, were currently undergoing or had completed reconstruction, and were in a committed romantic relationship at the time of the surgery were surveyed (N = 53). The hypotheses that women who received negative feedback about their decision to have a PBM would have poorer individual well-being, and that the use of a couples-based team approach would moderate these adverse effects were tested. Data analyses support the hypotheses that women in couples taking a team approach to PBM have better individual well-being. The effects of negative feedback from others about the decision to undergo a PBM on personal mental health were moderated by use of a couples-based team approach. Women who received negative feedback from multiple sources had better outcomes if they used a couples-based team approach. Many women have a preventative oophorectomy around the same time as their PBM. Menopause is associated with side effects such as increased vasomotor symptoms and decreased sexual functioning. The hypothesis that surgical menopause is related to declines in sexual satisfaction following PBM was also tested. Regression analysis revealed no relationship. This study indicates that women who experience social disapproval and lack collaborative support from their significant other may be at increased risk for poor individual well-being following PBM.
ContributorsGaytán, Jenelle A (Author) / Burleson, Mary H (Thesis advisor) / Roberts, Nicole A. (Committee member) / Mickelson, Krisitin D (Committee member) / Arizona State University (Publisher)
Created2018
Description
In this thesis, a digital input class D audio amplifier system which has the ability
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.
ContributorsBai, Jing (Author) / Bakkaloglu, Bertan (Thesis advisor) / Arizona State University (Publisher)
Created2015
Description
Emerging adulthood--a developmental point in the life span (usually between the ages of 18-25) during which children no longer see themselves as adolescents but would not yet consider themselves adults--is marked by identity exploration and discovering new life directions. When emerging adults find themselves serving as caregivers for their parent during a time when they would normally be establishing autonomy and exploring new directions, they may feel conflicted by their desire to both care for their parent and maintain a sense of independence. Thus, using a multiple-method research design that includes both an autoethnography and a qualitative content analysis of young adult caregivers' online posts, this study intends to uncover the dialectical tensions (the interplay of communicative tensions within a relationship) an emerging adult daughter experiences in her relationship with her mother as she serves as her caregiver, experiences her death, and grieves her passing by analyzing the author's personal narrative. To provide a deeper understanding of the dialectical nature of the emerging adult caregiver experience, the study was extended with an examination of other young caregivers' experiences, drawn from online forums, to explore how they encounter tensions within their own relationships with their parents. An analysis of the personal narrative revealed one primary dialectical tension, separation-connection, and three interrelated tensions--predictability-change, openness-closedness, and holding on-letting go--that seemed to influence this primary tension. Results of the qualitative content analysis revealed that other caregivers experienced one primary dialectical tension, sacrifice-reward, and two additional, interrelated tensions: independence-dependence and presence-absence. A comparison of the findings from each methodological approach revealed both similarities and differences in experiences of emerging adult caregivers.
ContributorsPiemonte, Nicole Marie (Author) / Fisher, Carla (Thesis advisor) / Kelley, Douglas (Committee member) / Waldron, Vincent (Committee member) / Wolf, Bianca (Committee member) / Arizona State University (Publisher)
Created2010
Description
Bexarotene is a Food and Drug administration (FDA)-approved therapeutic used in the treatment of cutaneous T-cell lymphoma (CTCL). However, bexarotene therapy causes significant side effects like hyperlipidemia and hypothyroidism due to crossover activity with retinoic acid receptor (RAR), thyroid hormone receptor (TR), and liver X receptor (LXR) signaling, respectively. More recently bexarotene has shown promise to reverse neurodegeneration, improve cognition and decrease levels of amyloid- β in transgenic mice expressing familial Alzheimer’s disease (AD) mutations. Bexarotene is a high affinity ligand for the retinoid X receptor (RXR) that heterodimerizes with the liver- X- receptors (LXR) and with peroxisome proliferator-activated receptor-gamma (PPARϒ) to control cholesterol efflux, inflammation, and transcriptionally upregulates the production of apolipoprotein (ApoE) in the brain. Enhanced ApoE expression may promote clearance of soluble Aβ peptides from the brain and reduce Aβ plaques, thus resolving both amyloid pathology and cognitive deficits. The present study assessed the potential of bexarotene and a group of 62 novel rexinoids to bind and activate RXR using a series of biological assays and screening methods, including: 1) a mammalian two-hybrid system (M2H) and an 2) Retinoid X Receptor response element (RXRE)-mediated reporter assays in cultured human cells. Moreover, Liver X Receptor response element (LXRE)-mediated luciferase assays were performed to analyze the ability of the novel analogs to activate LXRE - directed transcription, and to induce ApoE messenger ribonucleic acid (mRNA) in U87 glial cells. Furthermore, the most potent analogs were analyzed via quantitative polymerase chain reaction (qPCR) to determine efficacy in modulating expression of two critical tumor suppressor genes, activating transcription factor 3 (ATF3) and early growth response 3 (EGR3). Results from these multiple assays indicate that the panel of RXR ligands contains compounds with a range of activities, with some analogs capable of binding to RXR with higher affinity than others, and in some cases upregulating ApoE expression to a greater extent than bexarotene. The data suggests that minor modifications to the bexarotene core chemical structure may yield novel analogs possessing an equal or greater capacity to activate RXR and may be useful as therapeutic agents against CTCL and Alzheimer’s disease.
ContributorsReshi, Sabeeha Mushtaq (Author) / Jurutka, Peter (Thesis advisor) / Wagner, Carl (Committee member) / Marshall, Pamela (Committee member) / Arizona State University (Publisher)
Created2023